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Artículos publicados en: 2021

Energy and bandwidth-efficient channel access for local area machine-to-machine communication
Wireless Networks
https://doi.org/10.1007/s11276-020-02463-4
José Jaime Camacho Escoto 1 , Rolando Menchaca Mendez 2 , Ricardo Menchaca Mendez 2 , Jorge Bernal 2 , Mario E. Rivero Angeles 2 , Javier Gómez 1 , J. J. García Luna Aceves 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Centro de Investigación en Computación
3 University of California, Department of Computer Science and Engineering

Keywords: Device to-device networks, IoT, Machine-to-machine communication, Medium access protocols, Energy eff
Abstract: Ticket Election Multiple Access (TEMA) is introduced for local machine-to-machine communication that is energy and bandwidth-efficient. TEMA is based on distributed elections held among nodes to gain interference-free access to the channel in either unicast or broadcast mode. Non-transmitting nodes can infer whether or not they are the intended receiver of a transmission and act accordingly to save energy, without the need for particular traffic patterns or explicit future transmission schedules. TEMA is shown to be correct in the sense that the channel access schedules are collision-free at the intended receivers, and intended receivers are always in receiving state. An analytical model of the performance of the protocol is used to show that TEMA attains energy-efficiency and high channel utilization even under heavy traffic and high node density conditions. A simulation-based performance analysis validates the analytical results and shows that TEMA outperforms representatives of contention-based and interference-free protocols in terms of energy efficiency, network goodput, and channel access delay. More specifically, it reduces energy consumption to half of that of state-of-the-art distributed election-based protocols while providing up to 25% increase in goodput and up to 50% decrease in channel access delay.
Control of islanded microgrids considering power converter dynamics
International Journal of Control
https://doi.org/10.1080/00207179.2020.1713402
Sofía Ávila Becerril 1 , Gerardo Espinosa Pérez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Microgrids, Hamiltonian systems, passivity-based control
Abstract: In this paper, the control problem of Islanded Microgrids is approached. A controller scheme that considers the necessity to assure the generation of grid-forming nodes as well as the proper operation of grid-following nodes is proposed. The main feature of the contribution is the explicit inclusion of the dynamic of the power converters existing in this kind of networks making possible the evaluation of the system performance under sudden and fast changes in the operating conditions typically found in these applications. The scheme uses only the measurement of local variables and guarantees that both voltages and currents of the network achieve the values required to satisfy a prescribed power balance imposed by the loads. The design of the proposed controller is carried out by exploiting a Port-Controlled Hamiltonian representation of the system and applying the Passivity-based Controller design methodology. The stability properties of the closed-loop system are formally proved and its usefulness is illustrated via numerical simulations.
Robust global stabilization of a class of underactuated mechanical systems of two degrees of freedom
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5176
Diego Gutiérrez Oribio 1 , José A. Mercado Uribe 2 , Jaime Alberto Moreno Pérez 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: finite-time convergence, higher order sliding mode control, nonlinear control, underactuared systems
Abstract: In this article, the global stabilization of a class of underactuated mechanical systems of two degrees of freedom (DoF) is addressed, despite the presence of Lipschitz disturbances and/or uncertainties and uncertain control coefficient in the model. Using two second?order continuous sliding modes algorithms, the control task is performed, reaching finite?time convergence in one part of the dynamics and generating a continuous control signal. The efficacy of the proposed controllers is illustrated via simulations for the reaction wheel pendulum (RWP) and the translational oscillator with rotational actuator (TORA) systems, and by means of experiments on the RWP system, comparing the presented algorithms with a linearizing controller.
Temperature and frequency dependence of dielectric relaxations in YFeO3
Ceramics International
https://doi.org/10.1016/j.ceramint.2020.12.124
O. Rosales González 1 , Fernando Pedro García 1 , Félix Sánchez De Jesús 1 , Arturo Barba Pingarrón 2 , M. Ramírez Cardona 1 , Ana María Bolarín Miró 1
1 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: YFeO3, Dielectric ceramics, Dielectric impedance, Impedance spectroscopy, Multiferroic
Abstract: We report a dielectric study in wide frequency and temperature ranges of yttrium orthoferrite, YFeO3, in order to obtain the temperature-frequency dependence of the dielectric relaxation processes. A mixture of oxide powders (Y2O3 and Fe2O3) was activated by high-energy ball milling. The mechanically activated powders were pressed and sintered at 1073 K. The cylindrical test samples were characterized at room temperature by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Broadband Dielectric Spectroscopy (BDS) studies were carried out at several temperatures to the best understanding of dielectric properties. The X-ray diffraction patterns show an orthorhombic YFeO3 single phase. The magnetic hysteresis loop shows a weak ferromagnetic behavior, characteristic of the YFeO3. Dielectric spectroscopy analysis allows identifying two relaxation processes, the first at temperatures between 193 and 253 K and second above 333 K, defined as low-temperature dielectric relaxation (LTDR) and high-temperature dielectric relaxation (HTDR), respectively. It was determined the activation around 0.4 eV and 1.0 eV for the LTDR and HTDR, respectively. It indicates a single and doubly ionized oxygen vacancy. Moreover, it was proved that a hopping model is the dominating mechanism in the studied material, due to the conduction mechanism follows the Jonscher power law.
A multiscale analysis approach to predict mechanical properties in fused deposition modeling parts
The International Journal of Advanced Manufacturing Technology
https://doi.org/10.1007/s00170-021-07287-w
Luis Sánchez Balanzar 1 , Fernando Velázquez Villegas 1 , Leopoldo Ruiz Huerta 2 , Alberto Caballero Ruiz 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: Additive manufacturing, Finite element analysis, Fused deposition modeling, Mechanical properties modeling, Multiscale modeling, Homogenization method
Abstract: Additive manufacturing has evolved from a rapid prototyping tool to a set of manufacturing processes for functional parts. One of their most outstanding features is the ability to build complex geometry parts. However, their industrial application is limited because these parts exhibit heterogeneous and porous micro/mesostructures with anisotropic behavior. These structural characteristics, mainly porosity, are strongly related to the building parameters. In this work, a computational multiscale homogenization approach was implemented to determine the mechanical properties of unidirectional and criss-cross mesostructures generated by a material extrusion process (MEP). Representative volume elements (RVE) for simplified and real-like pore geometries were created to model the mesostructures and to perform the multiscale analysis. Stiffness tensor for each RVE was obtained and graphically represented to observe the mechanical properties as a function of the orientation. A great influence of the pore geometry on mechanical properties was observed. Finally, by comparing with experimental data, the results obtained were validated.
Hydraulicity of lime plasters from Teotihuacan, Mexico: a microchemical and microphysical approach
Journal of Archaeological Science
https://doi.org/10.1016/j.jas.2021.105453
Domenico Miriello 1 , Luis Barba Pingarrón 2 , Arturo Barba Pingarrón 3 , Donatella Barca 1 , Andrea Bloise 1 , Jesús Rafael González Parra 3 , Gino Mirocle Crisci 1 , Raffaella De Luca 1 , Genea Girimonte 4 , José Luis Ruvalcaba Sil 5 , Alessandra Pecci 4
1 Università della Calabria, Dipartimento di Biologia
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones Antropológicas
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universitat de Barcelona, Archaeology Institute
5 Universidad Nacional Autónoma de México, Instituto de Física

Keywords: Plasters, Hydraulicity, C??S??H compounds, Glass shards, Tezontle volcanic scoria, Mesoamerica, Teotihuacan
Abstract: Hydraulicity is a well-known characteristic of mortars and plasters from the Roman, Late Roman, and Medieval periods, while the use of hydraulic mortars in pre-Columbian Mesoamerica and Central Mexico in particular, has not received equal attention. To address this issue, in this paper, we discuss the problem of hydraulicity and suggest a method to study it in Mesoamerican plasters. To prove the effectiveness of this method, we selected plaster samples from the archaeological site of Teotihuacan (Mexico), the main city of Central Mexico during the Classic period. The characterisation of plaster samples confirmed that, similar to other Teotihuacan plasters, they are made of two layers: the outermost layer (enlucido), composed of a mixture of lime and volcanic glass shards, and the underlying layer locally called firme, consisting of crushed volcanic scoria (tezontle) mixed with a mud-based binder. The compositional characterisation of the plasters confirmed their hydraulicity and the combination of microchemical (energy dispersive spectrometer (EDS) microchemical analysis), microphysical (Vickers microhardness), and petrographic (optical microscopy) measurements demonstrated that it was not the presence of glass shards in the external plaster layer which produced hydraulicity, as we originally thought. Instead, this was due to the reactivity of the tezontle, present in the lower layer. This suggests that the small thickness of the enlucido layer, in addition to save the amount of lime used, increased its performance, promoting chemical reactions with the tezontle in the contact layer and that the glass shards played another role in the mixture, rather than producing hydraulicity.
Imaging the structure of the Sun Pyramid (Teotihuacán, Mexico) from passive seismic methods
Engineering Geology
https://doi.org/10.1016/j.enggeo.2020.105969
José Piña Flores 1 , Martín Cárdenas Soto 1 , Alejandro Sarabia González 2 , Antonio García Jerez 3 , César A. Sierra Álvarez 4 , Mario A. Sáenz Castillo 4 , Francisco Luzón 3 , Francisco José Sánchez Sesma 5
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Antropología e Historia, Zona Arqueológica de Teotihuacán
3 Universidad de Almería, Departamento de Química y Física
4 Universidad EAFIT
5 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Ambient noise tomography, HVSR, Structure imaging, Sun Pyramid, Seismic vulnerability
Abstract: The Sun Pyramid in Teotihuacán, Mexico, belongs to the cultural heritage of Mexico and the world. Built nearly a millennium ago, the Pyramid is poorly known in terms of its mechanical properties. In order to assess these properties, we measured and studied the ambient seismic noise which has become a popular tool to explore non-invasively geological and human-made structures. This research is aimed to contribute to the structural diagnosis and seismic vulnerability assessment of this emblematic Mexican pre-Hispanic monument. We analyzed the horizontal-to-vertical spectral ratio and the cross-correlations of seismic ambient noise recorded during four hours by 15 broadband stations, distributed on different levels of the structure, and propose a three-dimensional velocity model for the Sun Pyramid in Teotihuacán. The processed data includes the stacking of cross-correlations. We identified arrivals corresponding to a rich mixture of body and surface waves. Group velocity dispersion curves were extracted from the symmetrized cross-correlation of vertical displacements between station pairs. The retrieved travel times between station pairs allowed a tomographic analysis based on the Fast Marching Method (FMM). Besides, simultaneous inversions of the local dispersion curves (obtained from the group velocity tomography) and the HVSR mitigate non-uniqueness of the retrieved P- and S-wave velocities. Our model reveals two main features of the Sun Pyramid: i) The low-velocity anomalies in the cover layer correlate well with the presence of support walls or counterforts that, apparently, were part of the construction technique seeking to provide support to weak parts of the Sun Pyramid. ii) The core of the structure, with soft material subjected to the action of infiltrated water, is susceptible to causing wall failures. These results could be useful to design conservation strategies for this emblematic Mexican pre-Hispanic monument.
Applying complex network theory to the analysis of Mexico city metro network
Case Studies on Transport Policy
https://doi.org/10.1016/j.cstp.2021.07.008
Salvador Hernández González 1 , Idalia Flores De La Mota 2
1 Tecnológico Nacional de México, Departamento Industrial
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Metro, Complex networks, Mexico City
Abstract: In the last fifty years, urban public passenger transport has undergone a huge transformation as cities grow, however, the transport system has not grown at the same speed. In the specific case of Mexico City, we analyzed the Metro public transport system, considering how it has changed over time; how it has become a network that can be analyzed from the perspective of complex networks, this approach is appropriate because it is a dynamic and stochastic network, which allows to study its evolution over time and how its evolution can be measured using the metrics for said networks. The results of the analysis show that the degree distribution in the Metro network has increasingly fitted in with the behavior of a scale-free network; the hub, betweenness and clustering indices also show that the stations with the highest values in each one of these measurements have been displaced from the central area and are now located in the eastern part of the city. In each period, the diameter of the network has increased at a variable rate. It must be pointed out that so far, the diameter has grown following a potential model without giving signs of an apparent contraction. Finally, an update of the current conditions of the subway as well as future work and recommendations are presented.
Graben type calderas: The Bolaños case, Sierra Madre Occidental, Mexico
Journal of Volcanology and Geothermal Research
https://doi.org/10.1016/j.jvolgeores.2021.107315
Gerardo J. Aguirre Díaz 1 , Margarito Tristán González 2 , Isaac Gutiérrez Palomares 1 , Joan Martí 3 , Margarita López Martínez 4 , Guillermo Labarthe Hernández 2 , Jorge Nieto Obregón 5
1 Universidad Nacional Autónoma de México, Centro de Geociencias
2 Universidad Autónoma de San Luis Potosí, Instituto de Geología
3 Consejo Superior de Investigaciones Científicas, Geosciences Barcelona
4 Centro de Investigación Científica y de Educación Superior de Ensenada, División de Ciencias de la Tierra
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Graben caldera, Volcano-tectonic structure, Large-volume ignimbrite, Supereruptions, Mid-Tertiary volcanism, North America
Abstract: Graben calderas are volcano-tectonic structures that use the faults of a graben as main vents from which magma is massively erupted from a shallow magma chamber during collapse of intra-graben blocks. These eruptions are generally silicic and explosive and form large volume ignimbrite sheets without a previous Plinian major depressurization event. Graben calderas can be associated to tectonic settings ranging from pure extension to strike-slip transtension, including complete grabens, half-grabens or pull-apart grabens. The Sierra Madre Occidental (SMO) in western Mexico includes several of these graben type calderas with the corresponding large volume ignimbrite sheets that result from fissure type eruptions along the graben's border and interior faults. The Bolaños graben constitutes one of the best examples of these tectonically controlled collapse calderas and is the second largest caldera of the world after Toba caldera. It is a 90 ? 25 km rectangular caldera and the vent of the 25.37 ± 0.36 Ma silicic Alacrán ignimbrite, with a minimum Dense Rock Equivalent volume of 2650 km3 (3800 km3 rock volume). Post-collapse silicic domes were emplaced just after the Alacrán ignimbrite from 25.02 ± 0.33 Ma to 23.94 ± 0.33 Ma, with a total minimum lava volume of 171 km3. Both ignimbrite and domes account for at least 2800 km3 rhyolitic magma output from Bolaños graben caldera, without considering the distal deposits, and in particular the co-ignimbrite ash-cloud deposit. We describe the characteristics of the Bolaños graben caldera focusing on its major products, the Alacrán ignimbrite and the post-collapse dome volcanism, providing the geological frame of the Bolaños graben area documented with 40Ar-39Ar ages. We finally propose a conceptual model to explain the dynamics of the Bolaños graben that can be applied to other similar volcano-tectonic depressions of the Sierra Madre Occidental and elsewhere in the world with similar geological settings.
Effect of the Cu content on the corrosion of (TiZrNiNb)100-xCux high-entropy alloys in NaCl solution
Materials Letters
https://doi.org/10.1016/j.matlet.2021.130389
E. Galindo 1 , Alba Covelo Villar 1 , Jesús Rafael González Parra 1 , A. Tejeda 2 , Miguel Ángel Hernández Gallegos 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords: High-entropy alloys, Corrosion, Amorphous structure, Hardness, Conductivity
Abstract: This study shows the differences of the microstructure, microhardnesss, crystalline structure and electrochemical properties of a (TiZrNiNb)100-xCux (x = 10, 15, 20, 25, 30) alloy when two manufacturing processes are applied: the arc melting (ingots) and the melt spinning process (ribbons). The results indicate higher anti-corrosion properties for the ribbon samples due to a higher amorphous structure with low electric conductivity which exhibits an improvement in hardness. This amorphous structure does not demonstrate dendritic segregation nor do the ingot samples; therefore, there is no evidence of intermetallic phases identified by the X-Ray analysis. The 10 and 15 at.% Cu alloy exhibited the highest corrosion resistance, regardless of the manufacturing route.
A multiphase texture-based model of active contours assisted by a convolutional neural network for automatic CT and MRI heart ventricle segmentation
Computer Methods and Programs in Biomedicine
https://doi.org/10.1016/j.cmpb.2021.106373
Erik Carbajal Degante 1 , Steve Avendaño 2 , Leonardo Ledesma 1 , Jimena Olveres 3 , Enrique Vallejo Venegas 4 , Boris Escalante Ramírez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ciencias
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
4 Centro Médico ABC, Cardiología

Keywords: Active contours, Convolutional neural network, Heart ventricle segmentation
Abstract: Background: Left and right ventricle automatic segmentation remains one of the more important tasks in computed aided diagnosis. Active contours have shown to be efficient for this task, however they often require user interaction to provide the initial position, which drives the tool substantially dependent on a prior knowledge and a manual process. Methods: We propose to overcome this limitation with a Convolutional Neural Network (CNN) to reach the assumed target locations. This is followed by a novel multiphase active contour method based on texture that enhances whole heart patterns leading to an accurate identification of distinct regions, mainly left (LV) and right ventricle (RV) for the purposes of this work. Results: Experiments reveal that the initial location and estimated shape provided by the CNN are of great concern for the subsequent active contour stage. We assessed our method on two short data sets with Dice scores of 93% (LV-CT), 91% (LV-MRI), 0.86% (RV-CT) and 0.85% (RV-MRI). Conclusion: Our approach overcomes the performance of other techniques by means of a multiregion segmentation assisted by a CNN trained with a limited data set, a typical issue in medical imaging.
Joint swing-up and stabilization of the Reaction Wheel Pendulum using Discontinuous Integral algorithm
Nonlinear Analysis: Hybrid Systems
https://doi.org/10.1016/j.nahs.2021.101042
Diego Gutiérrez Oribio 1 , José A. Mercado Uribe 2 , Jaime Alberto Moreno Pérez 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Finite-time stability, Nonlinear systems, Uncertain Systems, Robust control
Abstract: In this paper, a third-order discontinuous integral controller is designed to jointly swing-up and robustly stabilize in finite-time the upright position of the Reaction Wheel Pendulum (RWP) system, despite some uncertainties and perturbations. To show this, a numerical estimation of the domain of attraction of the controller is used. The control algorithm produces a continuous control signal, thus reducing the usual chattering effect of the sliding-mode controllers. The theoretical results of the paper are verified by simulations and experiments in a laboratory setup.
Proposal for greenhouse gas emissions reduction in public passenger transportation
Case Studies on Transport Policy
https://doi.org/10.1016/j.cstp.2021.07.009
Carmen García Cerrud 1 , Idalia Flores De La Mota 1 , Francisca Irene Soler Anguiano 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Emissions, Public passenger transport, Statistical spatial analysis
Abstract: This article presents a proposal for the reduction of greenhouse gas emissions from public passenger transport using geographic information systems and spatial statistical analysis considering one-route demand through the creation of an alternative scenario to the actual one by stablishing bus stops according to its associated demand.
Maternal overnutrition before and during pregnancy induces DNA damage in male offspring: A rabbit model
Mutation Research/Genetic Toxicology and Environmental Mutagenesis
https://doi.org/10.1016/j.mrgentox.2021.503324
Ana María Salazar 1 , Monserrat Sordo 1 , Erika Navarrete Monroy 1 , Pablo Pánico 1 , Andrea Díaz Villaseñor 1 , Rodrigo Montúfar Chaveznava 2 , Ivette Caldelas 1 , Patricia Ostrosky Wegman 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomédicas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Offspring, High-fat diet, DNA damage, Micronuclei, Oxidative stress
Abstract: Using a rabbit model, we investigated whether maternal intake of a high-fat and high-carbohydrate diet (HFCD) before and during pregnancy induces an increase in micronuclei frequency and oxidative stress in offspring during adulthood. Female rabbits received a standard diet (SD) or HFCD for two months before mating and during gestation. The offspring from both groups were nursed by foster mothers fed SD until postnatal day 35. After weaning, all the animals received SD until postnatal day 440. At postnatal day 370, the frequency of micronuclei in peripheral blood reticulocytes (MN-RETs) increased in the male offspring from HFCD-fed mothers compared with the male offspring from SD-fed mothers. Additionally, fasting serum glucose increased in the offspring from HFCD-fed mothers compared with the offspring from SD-fed mothers. At postnatal day 440, the offspring rabbits were challenged with HFCD or continued with SD for 30 days. There was an increase in MN-RET frequency in the male rabbits from HFCD-fed mothers, independent of the type of challenging diet consumed during adulthood. The challenge induced changes in serum cholesterol, LDL and HDL that were influenced by the maternal diet and offspring sex. We measured malondialdehyde in the liver of rabbits as an oxidative stress marker after diet challenge. Oxidative stress in the liver only increased in the female offspring from HFCD-fed mothers who were also challenged with this same diet. The data indicate that maternal overnutrition before and during pregnancy is able to promote different effects depending on the sex of the animals, with chromosomal instability in male offspring and oxidative stress and hypercholesterolemia in female offspring. Our data might be important in the understanding of chronic diseases that develop in adulthood due to in utero exposure to maternal diet.
Observer Design for a Class of Nonlinear Hamiltonian Systems
IFAC-PapersOnLine
https://doi.org/10.1016/j.ifacol.2021.11.066
Michael Rojas 1 , Christian Granados Salazar 1 , Gerardo Espinosa Pérez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Port-Controlled Hamiltonian System, Nonlinear observers, Structure preserving observers
Abstract: In this paper, the observer design problem for Port-Controlled Hamiltonian systems is approached. It is considered a particular class of these systems and a full-order order observer is proposed which belongs to the Structure Preserving approach since it is a copy of the original system with an output corrective term. Concerning the class of systems, it corresponds to nonlinear systems that exhibit nonlinearities given by the products between components of the state vector. The fact that this kind of behavior corresponds to a special property of the interconnection matrix is exploited to obtain a representation for the estimation error dynamics that is suitable to formally state the convergence properties of the observer. The usefulness of the contribution is illustrated by solving the speed observation problem for a Permanent Magnet Synchronous Motor.
Assessment of steam turbine blade failure and damage mechanisms using a Bayesian network
Reliability Engineering & System Safety
https://doi.org/10.1016/j.ress.2020.107329
David A. Quintanar Gago 1 , Pamela Nelson 1 , Ángeles Díaz Sánchez 2 , Michael S. Boldrick 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Investigaciones Nucleares, Nuclear Systems Department
3 Boldrick Systems

Keywords: Bayesian network, Damage mechanism, Steam turbine blade, Maintenance, Recursive noisy OR
Abstract: Damage mechanisms that affect components within complex machines are often hard to detect and identify, especially if they are difficult to access, inspect and/or that are under continuous duty, compromising the reliability and performance of systems. In this paper, a Bayesian network model is developed to handle the interactions among common damage mechanisms and failure modes in nuclear steam turbine rotating blades. This model enables maintenance and inspection planning to better predict which portions(s) of the turbine will need repair. To compute the conditional probability tables, the model's unique quantification method combines expert judgement, the Recursive Noisy OR, and a damage mechanism susceptibility ranking that takes into account the synergistic interactions of the damage mechanisms. The approach can be suited to different turbine designs and purposes. The Bayesian network model development is described in detail, validated, and several examples of its application are presented.
Neutronic analysis of the ALLEGRO fast reactor core with deterministic ERANOS code and Monte Carlo Serpent code
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2021.108567
Yrobel Lima Reinaldo 1 , Juan Luis François Lacouture 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Gas-cooled fast reactor, ALLEGRO, Ceramic fuel, Serpent, ERANOS
Abstract: The Gas-cooled Fast Reactor is an advanced concept selected to be part of the fourth generation of nuclear reactors. Before its development, the construction of the experimental demonstration reactor ALLEGRO is planned. Given the current interest in this innovative system, a neutronic study of the ALLEGRO reactor core is performed using the Monte Carlo Serpent calculation code and the deterministic ERANOS code. A detailed description of the core design and ceramic fuel composition is provided. To reduce the computational cost of the simulations for future applications, different cases are analyzed using different computational options in the TGV/VARIANT module and a 7-group energy structure. To validate the ERANOS models, the results are compared with the three-dimensional heterogeneous reference model developed in Serpent. The main parameters of the core, at the beginning of life, are calculated, such as the k-eff value, flux and power distributions, Doppler constant, effect of helium density on reactivity and the β-eff value. The main discrepancies in the results correspond to the diffusion and simplified transport calculations, due to the low density of helium. By using the 7-group structure, it was possible to reduce the calculation time with a reduced penalty in the precision of the results. Furthermore, the best agreement was obtained, with respect to the Serpent model, for the transport calculation (P3) with the 7-energy group structure. The k-eff and fuel isotope mass evolution during burnup is analyzed assuming an operating time of 365 days. The relative fuel fraction at the beginning and end of cycle, the breeding ratio and the average burnup are also given.
Novel solution to the fractional neutron point kinetic equation using conformable derivatives
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2021.108407
G. Fernández Anaya 1 , Sergio Quezada García 2 , Marco A. Polo Labarrios 3 , L. A. Quezada Téllez 1
1 Universidad Iberoamericana Ciudad de México, Departamento de Física y Matermáticas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Unidad Cuajimalpa

Keywords: Reactor dynamics, Fractional neutron point kinetic equations, Anomalous diffusion exponent, Conformable derivative, Multi term higher-order linear approximation
Abstract: This work presents a novel solution to Fractional-model equations, it is based on the applying of conformal derivative to fractional calculus and thus obtain a linear multi-term differential equations of integer order (Conformal-model). The main goal of this work is demonstrating the existences of the solutions for the Conformal-model, it is through constraint conditions obtained by the methodology proposed in this work, to analyze and determine the appropriate function to use in its solution and guarantee the stability. The methodology developed is applied to cases with one and six groups of delayed neutrons in abrupt reactivity changes in the reactor, and for the dynamics of startup of PWR nuclear reactor. The results show the main difference of the neutron density behavior among the methods applied to solve the Fractional-model, and against the Classical-model results. Results obtained from Conformal-model are compared against obtained using Fractional-model for different anomalous diffusion coefficient values.
11 - Adaptive control for second-order DC??DC converters: PBC approach
Modeling, Operation, and Analysis of DC Grids
https://doi.org/10.1016/B978-0-12-822101-3.00016-2
Walter Gil González 1 , Oscar Danilo Montoya Giraldo 2 , Gerardo Espinosa Pérez 3
1 Institución Universitaria Pascual Bravo, Facultad de Ingeniería
2 Universidad Tecnológica de Bolivar, Laboratorio Inteligente de Energía
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Second-order DC??DC converters, DC??DC converters modeling, Port-controlled Hamiltonian, Proportional??integral passivity-based control, General representation for second-order DC??DC converters
Abstract: This chapter deals with the design of a passivity-based controller for DC??DC converters by using a general representation for second-order converters, that is, buck, boost, buck-boost, and noninverting buck-boost converters. The main idea is to propose a dynamic structure for representing these converters by introducing some constants that allow compressing them into a unique representation. The general model obtained for these converters is a bilinear port-controlled Hamiltonian (PCH) representation, whose control input is multiplied by some state variables. This PCH structure allows designing a general proportional??integral controller with passive output that ensures the asymptotic stability for closed-loop operation in the Lyapunov sense. Numerical results demonstrate that the general proposed control scheme allows regulating the voltage output of all the converters with minimum errors and adequate responses during step changes in the reference signal.
Closed-loop online harmonic vibration estimation in DC electric motor systems
Applied Mathematical Modelling
https://doi.org/10.1016/j.apm.2021.01.021
Francisco Beltran Carbajal 1 , Rubén Tapia Olvera 2 , Antonio Valderrabano González 3 , Hugo Yáñez Badillo 4 , Julio Cesar Rosas Caro 3 , Jonathan Carlos Mayo Maldonado 5
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Panamericana, Facultad de Ingeniería
4 Tecnológico de Estudios Superiores de Tianguistenco, División de Mecatrónica
5 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias

Keywords: DC Motors, Motion planning tracking, Vibrating signal modelling, Vibration estimation, Active vibration control, Differential flatness
Abstract: In this article, an active vibration control technique for direct-current electric motors subjected to harmonic mechanical load torque is introduced. Formulae to compute uncertain parameters of amplitude, frequency and phase angle of harmonic torque disturbances for angular velocity reference trajectory tracking are proposed. Vibrating torque disturbances are actively suppressed by the control voltage input. Mathematical modelling based on vibrating systems is adopted for purposes of online parameter estimation of oscillating signals. In this fashion, accurate estimation can be performed using measurements of the output signal only. Online parameter estimation is extended for a class of controllable dynamical engineering systems subjected to harmonic disturbances. Formulae for closed-loop online parameter estimation of harmonic vibrations on differentially flat linear dynamical systems of degrees of freedom for efficient tracking of desired time-varying motion reference profiles are then presented. Analytical and numerical results prove that proposed formulae can be used to accurately determine the parameters of unknown harmonic vibrations, which is an excellent feature for high-efficiency active vibration control strategies.
Hermite transform-based algorithm to discriminate magnetizing currents in transformers
Sustainable Energy, Grids and Networks
https://doi.org/10.1016/j.segan.2021.100493
Daniel Guillen 1 , Jimena Olveres 2 , Héctor Esponda 3 , Boris Escalante Ramírez 4 , Vicente Torres García 4 , Rubén Tapia Olvera 4
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
3 Universidad Autónoma de Nuevo León, Posgrado de Ingeniería Eléctrica
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Differential protection, Fault detection, Inrush current, Internal fault, Hermite transform, Multiresolution analysis, Power transformer
Abstract: This work proposes a new method based on the Hermite transform with the aim of identifying transient events in power transformers caused by energizations and current transformer (CT) saturation. The Hermite transform is a signal processing technique that allows the representation of signals in the time??frequency domain as well as at multiple resolution levels. Gaussian derivatives analyze the signals in the proposed scheme according to the Hermite transform theory. The newly introduced approach is based on a differential scheme considering three functions, the first one to analyze the positive half-cycle and the second one for the negative half-cycle. The latter is a new blocking function for the detection of transient conditions, that is, the operation command is disabled; otherwise, the third function will confirm if the condition is an internal fault. To validate the performance of the proposed method, several fault conditions are addressed, such as load switching, internal and external faults, current transformer saturation, and single-phase-to-ground faults. Results show the effectiveness of the proposed method, which improves the differential protection performance to discriminate transient conditions from internal faults.
Neutronic analysis of the NuScale core using accident tolerant fuels with different coating materials
Nuclear Engineering and Design
https://doi.org/10.1016/j.nucengdes.2021.111169
Sadiel Pino Medina 1 , Juan Luis François Lacouture 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: NuScale, ATF, Coating materials, Monte Carlo, Serpent
Abstract: The design flexibility of small modular nuclear reactors in synergy with accident-tolerant fuels provides a longer time to react to the loss of active cooling under severe accidents and offers comparable fuel performance during normal operation. The NuScale reactor has an integrated design with a fuel enrichment below 5%, a thermal power of 160 MW and 24-month operating cycles, also guaranteeing safe shutdown by redundant passive systems. In this work, the core of the NuScale reactor is simulated with the Serpent Monte Carlo code, with the objective of analyzing important steady-state core parameters and making a comparison using U3Si2 fuel with different coating materials. The results predict the behavior of the core through the neutron multiplication factor and ppm of boron vs fuel burnup, the Doppler, the moderator density and the temperature reactivity coefficients, the radial and axial power distributions and the neutron spectrum of each of the studied fuels and coating materials. The results show that the operation of the reactor with these materials is safe and feasibly according to the analyzed neutron parameters.
Numerical modelling of the saline interface in coastal karstic aquifers within a conceptual model uncertainty framework
Hydrogeology Journal
https://doi.org/10.1007/s10040-021-02379-z
César Canul Macario 1 , Paulo Salles 1 , Antonio Hernández Espriú 2 , Roger Pacheco Castro 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Numerical modelling, Coastal aquifers, Karst, Conceptual models, Mexico
Abstract: Numerical modelling is increasingly used as a tool for improving management strategies in aquifers and to support the design of comprehensive projects considering natural and anthropogenic processes. Overall, numerical simulation in karstic aquifers poses a major scientific challenge due to the non-Darcian groundwater flow dynamics. In specific cases, the equivalent porous medium approach has shown acceptable results, particularly in poorly karstified aquifers with regional/subregional scales such as this case. The Yucatan coastal karstic aquifer (Mexico) has been defined as a complex regional heterogeneous system, partially confined, thus allowing the discussion of multiple conceptual models. In this research, a two-dimensional numerical model of flow and transport was implemented using SEAWAT for the NW Yucatan aquifer. Four likely conceptual models were audited, calibrated and verified using hydrogeological field data, to select the best one, considering their fit and complexity. The numerical model accuracy was evaluated using the root-mean-square error, Nash Sutcliffe efficiency and the Pearson coefficient. The Akaike information criterion and Bayesian information criterion were included for evaluating the complexity of the numerical models. In addition, the signal of tide propagation into the aquifer was assessed as a proxy to improve the numerical calibration process. Results show that the most complex numerical model has a better calibration than the simpler models, but the model accuracy is worse when compared to less complex numerical models in the verification exercise. This research offers enhancement in the knowledge of numerical modelling in heterogeneous coastal aquifers within a conceptual-model uncertainty setting.
Secured telemedicine of medical imaging based on dual robust watermarking
The Visual Computer
https://doi.org/10.1007/s00371-021-02267-3
David Mata Mendoza 1 , Manuel Cedillo Henández 1 , Francisco Javier García Ugalde 2 , Antonio Cedillo Hernández 3 , Mariko Nakano Miyatake 4 , Héctor Pérez Meana 3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación
4 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias

Keywords: Digital watermarking, Information security, DICOM imaging, Authentication, Detachment avoidance
Abstract: Medical information management has progressed in the last few years because of the advances in information technologies. Nowadays, it is possible to share medical images among specialists geographically distant to interpret, discuss, and get improved diagnostics. However, any alteration of transmitted image metadata may lead to issues related to information security, such as detachment and authentication. Detachment refers to link the data of an electronic patient record to an incorrect medical image, while authentication aims to identify the image source. These security problems are critical as they may cause the loss of sensitive data or wrong medical diagnoses. Digital watermarking is an emerging technique that faces these security problems as it allows to embed the metadata directly into the medical image. This paper proposes a hybrid and robust watermarking technique to prevent detachment and authenticate medical images. The quantization index modulation algorithm under dither modulation in conjunction with forwarding error correction is used to embed relevant metadata as a robust-imperceptible watermarking to avoid detachment. The visible-imperceptible watermarking paradigm, whose use is an innovation in medical images, is applied to insert a second watermark in the spatial domain to perform authentication. The experimental results show the contribution of the proposed scheme and its efficiency regarding robustness and imperceptibility.
Seismic ambient noise tomography to retrieve near-surface properties in soils with significant 3D lateral heterogeneity: the case of Quinta Colorada building in Chapultepec, Mexico
Natural Hazards
https://doi.org/10.1007/s11069-021-04735-4
Martín Cárdenas Soto 1 , José Piña Flores 1 , David Escobedo Zenil 1 , Martín Carlos Vidal García 1 , Thulassiraman Natarajan 2 , Yawar Hussain 3 , Francisco José Sánchez Sesma 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Indian Institute of Science, Centre for Earth Sciences
3 University of Liege, Department of Geology
4 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Local subsidence, Ambient noise tomography, Seismic interferometry, HVSR method, Surface waves
Abstract: Structural failure due to local soil subsidence is a severe issue in the urban environment, particularly in cities located on thick sediments. We present such a case from Mexico City, where the near-surface soil characteristics beneath a subsided building were examined using 3D ambient noise tomography. We acquired data using dense arrays of 4.5 Hz vertical geophones placed around the building in two geometries. We performed cross-correlation analyses for 12 central frequencies in the range of 4??12 Hz to built tomographic images of surface wave group velocity. The results indicated a low-velocity layer (~??120 m/s) for the first 10 m depth which we interpret as the typical clay layer of the Lake Zone of the city. Below, a more complex stiff layer (~??500 m/s) appeared with significant lateral variations. In another independent analysis of HVSR, we observed that the site period varied between 0.4 and 0.55 s, which further signify the complexity of the subsurface. Thus, the conspicuous structural failure was due to the lack of stiffness of the shallow foundation, which subjected to differential motions between consistent materials from the foot of Chapultepec hill, and the soft lacustrine clays of the Lake Zone. As shown in this case, the seismic response variations in short distances, and short periods, for near-source events could be of great importance as demonstrated in Mexico City during the recent Puebla-Morelos Earthquake (M7.1) of September 19th, 2017.
X-ray technique for visualization of the bolus flow through an esophageal simulator
Journal of Visualization
https://doi.org/10.1007/s12650-021-00743-5
Leopoldo Ruiz Huerta 1 , Carlos Alberto Palacios Morales 2 , Alberto Caballero Ruiz 1 , M. Vopalensky 3 , O. Díaz 1 , J. A. Hernández Angulo 1 , E. Brito de la Fuente 4 , Gabriel Ascanio 1
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Institute of Theoretical an Applied Mechanics of the Czech Academy of Sciences
4 Fresenius-Kabi Deutschland

Keywords: Soft actuatos, Esophageal simulator, Swallowing, Flor visualization, X-ray computed tomography, Biofluid mechanics
Abstract: In the last years, there has been an interest in development of simulators to reproduce the mechanical properties of the human digestive system. Particularly, there have been some approaches in the development of esophagus simulators. Such simulators intend to replicate the peristaltic wave conditions, but the reported experiments are related to indirect measurements in which the use of a fluid is not reported. In this work, an X-ray technique for visualizing the flow of bolus through an artificial esophageal simulator (AES) is proposed. For that purpose, particles of barium sulfate were thoroughly mixed with baby food, in order to create a suspension used as bolus. Barium sulfate particles used in the present work are insoluble in water with non-regular forms, a size distribution from 20 to 80 nm, and a specific surface area ranging from 10 to 50 m2/g. The advantage of using barium sulfate is its high absorption of X-rays, which allows obtaining a good contrast in radiographies, so that the transport of the bolus along the esophagus simulator can be easily tracked. The results revealed the appearance of secondary flows on the wave sides, which displace as the wave contracts. This was verified with the flow fields, in which it was observed that the bolus flows mainly along the central part of the wave and a small volume tends to retract. This confirms that the flow is extensional as the bolus is stretched and compressed during the peristalsis.
The historical case of Paricutin volcano (Michoacán, México): challenges of simulating lava flows on a gentle slope during a long-lasting eruption
Natural Hazards
https://doi.org/10.1007/s11069-021-04607-x
Laura Becerril 1 , Patricia Larrea 2 , Sergio Salinas 3 , Sophie Mossoux 4 , Dolors Ferrés 5 , Elisabeth Widom 6 , Claus Siebe 2 , Joan Martí 7
1 Geological Survey of Chile
2 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Vrije Universiteit Brussel, Department of Geography
5 Universidad Nacional Autónoma de México, Escuela Nacional de Ciencias de la Tierra
6 Miami University, Department of Geology and Environmental Earth Science
7 Consejo Superior de Investigaciones Científicas, Geosciences Barcelona

Keywords: Parícutin volcano, Michoacán-Guanajuato volcanic field, Monogenetic volcanism, Lava flow simulations, Volcanic hazard assessment, Q-LavHA
Abstract: Simulating lava flows on a gentle slope is complex since they can propagate in a wide range of directions. It is an even greater challenge to define lava flow trajectories when an eruption lasts over several years and flows cool down, changing the surrounding topography. In this study, we test Q-LavHA, an open source plug-in that simulates lava flow inundation calculating its probability, and using Paricutin??s eruption (1943??1952) in central Mexico as a case study. We have appropriately calibrated the Q-LavHA plug-in for the Paricutin case study, which provides insights on how to better model lava flows in gentle terrain. From this work, we observe that each phase is characterized by a unique set of parameters requiring a careful calibration and that low-relief topographies require special consideration. Our findings could be useful for real-time hazard evaluation in future volcanic scenarios in the Michoacán??Guanajuato volcanic field and elsewhere, where new monogenetic eruptions similar to Paricutin can be expected.
Effect of the Repetitive Corrugation and Straightening on the Microstructure and Mechanical Properties of a 3003 Aluminum Alloy
Physics of Metals and Metallography
https://doi.org/10.1134/S0031918X21050112
Carlos Reyes Ruiz 1 , Carlos Gabriel Figueroa Alcántara 1 , Gonzalo González 2 , Armando Ortiz Prado 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords: repetitive corrugated and straightening, AA3003, severe plastic deformation, microhardness, texture, EBSD
Abstract: A novel repetitive corrugation and straightening (RCS) die geometry was evaluated in terms of its mechanical properties and microstructural modifications. An annealed 3003 aluminum alloy sheet was processed up to 6 RCS passes at room temperature, showing a significant improvement in yield strength and hardness. Changes in surface profile values were obtained along different stages of the repetitive process; this showed a clear correlation between the higher strained region and the maxima of hardness values. Moreover, differences in roughness were associated with real contact area between material and corrugating die sections. Local strain distribution generated during the process was determined by kernel average misorientation (KAM) and was consistent with microhardness mapping results. Orientation image mapping showed that grains, with the normals parallel to ??111??, activate dislocation arrangement and grain fragmentation process prior to other main directions. In spite of mechanical properties improvement, initial texture components were maintained.
Landslide characterization using active and passive seismic imaging techniques: a case study from Kerala, India
Natural Hazards
https://doi.org/10.1007/s11069-020-04369-y
Farancisco J. Chávez García 1 , Thulassiraman Natarajan 2 , Martín Cárdenas Soto 3 , Kusala Rajendran 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Jawaharlal Nehru Centre for Advanced Scientific Research, Geodynamics Unit
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Indian Institute of Science, Centre for Earth Sciences

Keywords: Near surface geophysics, MASW, Seismic interferometry, Seismic tomography
Abstract: The unusually intense precipitations of the 2018 monsoon triggered numerous landslides in the Western Ghats region, southwest of India. Although the landslides caused no casualties, significant damage to property and infrastructure was observed. We present, as a case study, the results of active and passive seismic prospecting at two of those landslides with the goal of characterizing them, in a first application of shallow seismic exploration to landslides in the region. Our deployments included both sites perturbed by the landslides and unperturbed slopes adjacent to them with the purpose of identifying possible structural differences between slopes that underwent landsliding from slopes that were not affected. We analyze seismic sections obtained using the multi-channel analysis of surface waves technique and compare the results with seismic noise analyzed using seismic interferometry. We show that different analyses give similar results. The lateral variations observed in the shear-wave velocity distribution below the different profiles are well correlated with dominant frequency determined from seismic noise horizontal-to-vertical spectral ratios. Our measurements were taken after the landslides occurred. In hindsight, our results suggest that soil thickness played a major role in the triggering of landslides.
Sustainable Beekeeping Cooperative Societies: The Case of Mexico City
International Journal of Food Science and Agriculture
http://dx.doi.org/10.26855/ijfsa.2021.03.011
Aida Huerta Barrientos 1 , Alma E. Vera Morales 1 , Laura P. Avila Callejas 1 , Miguel A. Saldaña Cabrera 1 , Eduardo García López 1 , Emiliano Gutiérrez Ayala 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Beekeeping, Mexico City, Innovation Process, Sustainability, Cooperative Societies
Abstract: Beekeeping is an activity of great relevance for natural ecosystems with social and economic dimensions. Unfortunately, the practice of beekeeping in Mexico City face challenges as following: the use of outdated technology that leads to low productivity, the poor organization for production and marketing that generates low economic profitability, the marketing controlled by the intermediary which eliminates the sustainable local value chain of honey in which local cooperatives societies participate. In this direction, the purpose of this chapter is to develop a model of socio-cultural innovation, which revalue the beekeeping of Mexico City as a traditional activity of ecological importance and improve its position as a sustainable productive activity of honey with the participation of local cooperatives societies. Firstly, we identify the beekeeping cooperative societies located in Mexico City. Secondly, we characterize the feasible opportunities of marketing of honey and its derivates in the context of Mexico City that leads to revalue the beekeeping as a traditional activity of ecological importance. Thirdly, we analyze the main characteristics of sustainable honey production models. Finally, we characterize a socio-cultural innovation model and integrate it to the cooperative business model for sustainable beekeeping. We consider that the main results of this study contribute to the sustainable development of beekeeping in Mexico City.
The extended Recursive Noisy OR model: Static and dynamic considerations
International Journal of Approximate Reasoning
https://doi.org/10.1016/j.ijar.2021.09.013
David A. Quintanar Gago 1 , Pamela Nelson 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Recursive Noisy Or, Causality, Conditional probability table, Synergy
Abstract: Many engineering problems rely on causal reasoning to analyze the interactions among the numerous causes/variables. Probabilistic graphical models (e.g., Bayesian networks) are widely used for such analyses, but the conditional probability tables (CPTs) grow exponentially with respect to the number of variables (nodes). Several canonical models have been developed to reduce the amount of information needed to complete the CPTs. In this paper, the Extended Recursive Noisy OR (ERNOR) is developed. It is an improved version of the long-established RNOR, in that it resolves the asymmetry problem when the number of causes exceeds three. Like RNOR, it is not restricted to the independence of causal influence, thus synergy can be considered. The dynamic form of the ERNOR is also developed, which provides a continuous causal influence function. This function is dependent on cumulative distributions that represent the presence level of each time-dependent cause, useful for models that do not rely on CPTs. The derivation of the ERNOR is presented, and it is contrasted with its predecessor, the RNOR.
Social and environmental conflict analysis on energy projects: Bayesian predictive network approach
Energy Policy
https://doi.org/10.1016/j.enpol.2021.112515
Isaac Hernández Cedeño 1 , Pamela Nelson 1 , Marisol Anglés Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones Jurídicas

Keywords: Socio-environmental conflicts, Renewable energy, Sustainable energy
Abstract: This paper analyzes the social and environmental aspects of energy and large-scale projects through the use of Bayesian Networks. To do this, a database was created that includes conflict causes related to 267 projects in Mexico with 12 well-defined and orthogonal social and environmental conflict causes. These are lack of information and participation, fear of change to local communities, health and environmental damage, reduction of primary sector activities, proximity to cultural landmarks, employee dissatisfaction, political interests, violence to the community, water use, non-compliance of agreements, land use disputes, and others not defined. The database was the input for two Bayesian Networks, network "A? estimates the likelihood of approval or risk of suspension of a project because of the conflict causes, with an overall accuracy of 80.3%. The network "B? estimates the costs of conflictive situations and how likely they can be resolved by adding benefits. A sensitivity analysis found that five conflict causes can reduce the probability of a project's success by 10??39%. Finally, policy implications were identified, resulting in four recommendations for implementation in national regulations. The tools developed here enable measurement of the benefits of energy projects, provide policymakers tools to improve public decisions, and help avoid conflicts.
Reaction wheel pendulum control using fourth-order discontinuous integral algorithm
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5268
Diego Gutiérrez Oribio 1 , José A. Mercado Uribe 2 , Jaime Alberto Moreno Pérez 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: finite-time convergence, higher-order sliding-mode control, nonlinear control, tracking control,wheel pendulum
Abstract: The fourth-order model of the reaction wheel pendulum is considered and a fourth-order discontinuous integral algorithm is used for stabilization and tracking of the system, using a continuous control signal. The states reach the origin or a reference signal in finite-time, even in presence of uncertain control coefficient and a kind of matched and unmatched uncertainties/disturbances. A homogeneous Lyapunov function is designed to ensure local finite-time stability of the system, which can be used for designing the controller gains. Simulations and experimental results illustrate the performance and advantages of the presented algorithm.
A power optimization model for the long-term planning scenarios: Case study of Mexico's power system decarbonization
The Canadian Journal of Chemical Engineering
https://doi.org/10.1002/cjce.23986
Marco Antonio Martínez Quintana 1 , Cecilia Martín del Campo 1 , Guadalupe Cruz Mendoza 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: decarbonization, energy planning, Mexico, optimization, power system
Abstract: Mexico is committed to reducing its CO2 emissions according to the Paris Agreement. A relevant effort must be made for the analysis of Mexico's electric energy system towards a progressive decarbonization with a larger participation of intermittent renewable energies. The analysis of power planning scenarios, with different assumptions on costs, emissions, and intermittent performance of the power generating technologies, is needed to make sustainable decisions in the transition toward a cleaner power sector. Tools for energy modelling are required to develop and analyze scenarios with minimum costs subject to environmental constraints. The purpose of the article is to explain the modelling approach of a novel and flexible power planning tool, which is based on a well-known linear programming optimization method combined with a computing strategy to optimize time consumed for reading, processing calculations, and writing the huge number of economic and technical parameters required for the hourly power dispatch in complex interconnected electric systems. The time consumed has been optimized by means of a binary matrix that activates the input and use of only the data needed for the solution of the problem. The paper describes the MC model and demonstrates some of its analytical capabilities through a Mexican case study with a least cost scenario and two decarbonization scenarios of the power interconnected system for the period from 2020-2050.
Long-term planning scenarios of new nuclear capacity in Mexico using the IAEA INPRO methodology
International Journal of Energy Research
https://doi.org/10.1002/er.6847
Emilio Javier Yañez 1 , Cecilia Martín del Campo 1 , Juan Luis François Lacouture 1 , Federico Puente Espel 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico y de Estudios Superiores de Monterrey, Divisón de Ingeniería y Arquitectura

Keywords: INPRO, new nuclear capabilities, nuclear energy expansion in Mexico, nuclear fuel cycle, planning scenarios
Abstract: One of the medium and long-term objectives that nations with nuclear technologies focus on is to obtain more sustainable nuclear systems and make optimal use of nuclear resources. The International Atomic Energy Agency, through the INPRO collaborative project, proposes a series of strategies and tools focused on this purpose, which have been used in this work. Therefore, based on these tools: Nuclear Fuel Cycle Simulation System, KIND Evaluation Tool, and MESSAGE, this article proposes a methodology for assessing nuclear scenarios that covers, through key indicators, features involved in the nuclear fuel cycle and economic aspects to determine the best ones. Three scenarios that foresee the incorporation of new nuclear power plants in Mexico were set-up and studied. In the first scenario (E1), the introduction of AP1000 reactors from 2030 is analyzed with a frequency of introduction of a reactor every 4??years. The second scenario (E2) is like the previous one with the particularity that it incorporates a share of 30% fuel MOX in the reactor core. The third scenario (E3) considers the introduction of AP1000 reactors and EFR fast reactors type from the year 2062 with 80% fuel reprocessing. In order to be able to make a proper comparison, all the scenarios cover the time horizon until the year 2100 and were set-up in such a way that the final energy delivered is 15??000 GWh. The variables involved in the nuclear fuel cycle of each scenario were obtained and the best proposed alternative was quantitatively determined. For the studied alternatives (E1, E2, and E3 scenarios) the superiority is evident in the entire nuclear fuel cycle for fast reactor technologies and nuclear fuel reprocessing, but the cost associated to them is higher compared to more conservative alternatives such as the case of the E2 scenario. Therefore, it is considered that an immediate nuclear expansion in the case of Mexico would contemplate in the first instance AP1000 reactors.
Close Band Spacing Pentaband Frequency Selective Surfaces based on Concentric Ring Slots Surface Based on Loaded Ring Slots
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3072592
Lourdes Martínez López 1 , Rosalba Martínez López 1 , Alexander Martynyuk 1 , Jorge Rodríguez Cuevas 1 , Henry Fabian Gongora 2 , José Ismael Martínez López 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma de Campeche, Facultad de Ingeniería

Keywords: Frequency selective surfaces, Geometry, Resonant frequency, Prototypes, Apertures, Numerical simulation, Numerical models
Abstract: This paper presents a polarization insensitive frequency selective surface (FSS) based on concentric ring slots with five closely spaced passbands. The proposed FSS unit cell contains five ring slots coupled with a supplementary innermost ring slot. The close band response within the first five transmission bands is achieved by the influence of the modified geometry obtained with the inclusion of the sixth ring slot. This added ring slot causes the appearance of a stopband, due to the conductive ring between the fifth and the sixth ring apertures, and a passband produced inherently by the sixth ring aperture. The effect of the additional stopband and passband in the FSS response has been investigated in the paper. Full-wave simulations reveal that a modified geometry with proper sizes effectively enables the close band response of the pentaband FSS. To validate the proposed approach, a 729-element penta-bandpass FSS prototype operating at millimeter-wave frequencies has been designed, fabricated, and tested. Experimental results in a free-space measurement setup indicate resonances at f 1 = 26.7, f 2 = 29.8, f 3 = 33.6, f 4 = 38.1, and f 5 = 44.2 GHz, with resonant frequency ratios of f 2 / f 1 = 1.12, f 3 / f 2 = 1.13, f 4 / f 3 = 1.13, and f 5 / f 4 = 1.16. This FSS demonstrates an extremely low ratio of the highest and the lowest resonant frequencies ( f 5 / f 1 = 1.66) for a penta-band operation. This polarization insensitive FSS demonstrates good performance at oblique angular incidence for elevation angles up to 45°.
A Dual Circularly-Polarized Multilayer Reflective Surface Based on Loaded Ring Slots
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3049252
Lourdes Martínez López 1 , Rosalba Martínez López 1 , Jorge Rodríguez Cuevas 1 , Alexander Martynyuk 1 , José Ismael Martínez López 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Coplanar waveguides, Reflection, Polarization, Phased arrays, Nonhomogeneous media, Surface waves, Loading
Abstract: In this paper, a dual circularly-polarized multilayer reflective surface (MRS) based on loaded ring-slots for reflectarray applications is presented. The MRS comprises a wideband multilayer circular polarizer cascaded with a multilayer reflective screen with independent phase shifting properties for the two orthogonal linearly polarized components. The first polarization conversion is accomplished by a four-layer polarizer based on periodic arrays of bisected split rings that converts two incident circularly-polarized waves, one left-handed (LHCPW) and other right-handed (RHCPW), into two linearly polarized waves with orthogonal polarization planes. These two waves can be phase-shifted independently by a periodic two-layer array of specially designed reflective elements. Each element consists of a ring-slot resonator loaded with two pairs of reactances orthogonally located that can be varied to obtain two linear reflection phase tapers along the array. These reflected waves are then transformed back by the polarizer into two circularly polarized waves traveling into the desired directions. To validate the proposed approach, a six-layer prototype operating at 32 GHz that provides reflection elevation and azimuthal angles for the RHCPW at 22° and 180°, respectively, and reflection elevation and azimuthal angles for the LHCPW at 18° and 0°, respectively, has been designed, fabricated, and experimentally verified.
Output-feedback Lyapunov redesign of uncertain systems with delayed measurements
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5464
Jing Xu 1 , Leonid Fridman Golredich 2 , Emilia Fridman 3 , Yugang Niu 1
1 East China University of Science and Technology, Key Laboratory of Advanced Control and Optimization for Chemical Process
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Tel Aviv University, School of Electrical Engineering

Keywords: Lyapunov redesign, output-feedback, control robustness, state estimation, time-delay
Abstract: This paper presents an output-feedback Lyapunov redesign for uncertain systems with the delayed measurements, which recasts the state estimation and robust control into a unified framework. Instead of the traditional observer/differentiator-based output-feedback design, a static state estimator is constructed by the Taylor expansion of delayed measurements with the integral remainders. Then, a sliding variable is constructed according to the nominal Lyapunov function. A Lyapunov redesign approach is used to keep the system trajectory in predefined vicinity of origin, even subject to approximation errors and exogenous disturbances. The maximum value of the allowable delays for the closed-loop stability is found via linear matrix inequalities. Finally, the effectiveness of the proposed method is verified in the magnetic suspension system.
Design of a PID-like continuous sliding mode controller
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5412
Ulises Pérez Ventura 1 , Jesús Mendoza Avila 1 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: frequency domain analysis, Lyapunov functions, robust control applications, sliding mode control
Abstract: A describing function-based design for the continuous sliding mode controller in the proportional integral derivative (PID) form (PID-CSMC) is provided. Two sets of the PID-CSMC gains are suggested. The Harmonic Balance is used to predict the amplitude and frequency of the main harmonic of chattering caused by the presence of fast-parasitic dynamics in the closed-loop. Predicted values of amplitude and frequency allow to compute the average power needed to maintain the trajectories of the system into real sliding modes. The methodology for selection of suboptimal PID-CSMC gains consists of amplitude of chattering and average power minimization, taking into account the presence of a critically damped actuator parameterizing the effects of parasitic dynamics. A novel homogeneous Lyapunov function proves that suggested sets of the PID-CSMC gains ensure, in theory, finite-time stability of the perturbed double integrator without parasitic dynamics, and exact compensation of Lipschitz perturbations. On the other hand, the Loeb's criterion allows to ensure that the PID-CSMC with suggested gains generates orbitally asymptotically stable fast-oscillations in the presence of fast-actuators.
Dual layer barrier functions based adaptive higher order sliding mode control
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5387
Hussein Obeid 1 , Salah Laghrouche 1 , Leonid Fridman Golredich 2
1 Universite Bourgogne Franche-Comté/UTBM,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: adaptive control, barrier functions, higher order sliding mode control, linear induction motor
Abstract: This article presents an adaptive discontinuous higher order sliding mode control (HOSMC) strategy for a disturbed chain of integrators of order n. This strategy employs a barrier function-based dual layer adaptation and it ensures the convergence of the sliding variable and its (n??????1) first derivatives to zero without requiring any information on the bounds of the disturbances or their derivatives. It consists in applying a barrier function-based adaptive super-twisting methodology compensating Lipschitz disturbances with some error, and a growing gain-based adaptive HOSMC which just needs to counteract this error. Real-time simulation platform is used to test the efficacy of the proposed strategy to control a linear induction motor considering dynamic end effects.
Robust output trajectory linearisation control for a class of linear time-varying systems
IET Control Theory & Applications
https://doi.org/10.1049/cth2.12090
Rosalba Galván Guerra 1 , Juan Eduardo Velázquez Velázquez 1 , Leonid Fridman Golredich 2 , Rafael Iriarte 2
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: The trajectory linearisation control of a non-linear system using only output information and considering the presence of matched and unmatched uncertainties/perturbations is presented. A continuous sliding mode controller is used to achieve finite-time tracking of a given continuous time-varying reference and assuring theoretically exact reconstruction of the matched and unmatched uncertainties/perturbations. The states are reconstructed theoretically exactly in finite time using a linear time-varying observer based on a high-order sliding mode framework. The proposed approach is validated using MATLAB simulations.
Model-free sliding-mode-based detection and estimation of backlash in drives with single encoder
IEEE Transactions on Control Systems Technology
https://doi.org/10.1109/TCST.2019.2956914
Michael Ruderman 1 , Leonid Fridman Golredich 2
1 University of Agder, Faculty of Engineering and Science
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Backlash, estimation, mechanical play, nonlinearities, sliding-mode observer, supertwisting algorithm (STA)
Abstract: Backlash is a frequently encountered problem for various drives, especially those equipped with a single encoder onside of the controlled actuator. This brief proposes a sliding-mode differentiator-based estimation of unknown backlash size while measuring the actuator displacement only. Neither actuator nor load dynamics are explicitly known, while a principal second-order actuator behavior is assumed. We make use of the different perturbation dynamics distinctive for different backlash modes and an unbounded impulse-type perturbation at impact. The latter leads to transient loss of the sliding-mode and allows for detecting an isolated time instant of the backlash occurrence. The proposed method is simple and insensitive to residual system dynamics. The approach is experimentally evaluated on the data collected from a two-inertia system with backlash in the coupling.
A polytopic strategy for improved non-asymptotic robust control via implicit Lyapunov functions
Nonlinear Analysis: Hybrid Systems
https://doi.org/10.1016/j.nahs.2020.100988
Alan Tapia 1 , Denis Efimov 2 , Miguel Bernal 3 , Leonid Fridman Golredich 1 , Andrey Polyakov 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Villenueve d'Ascq, Nord Europe Center
3 Instituto Tecnológico de Sonora
4 ITMO University, Department of Control Systems and Informatics

Keywords: Finite- and fixed-time convergence, Implicit Lyapunov functions, Homogeneity, Polytopic systems, Linear matrix inequalities
Abstract: This paper is concerned with finite- and fixed-time robust stabilization of uncertain multi-input nonlinear systems via the implicit Lyapunov function method. Instead of splitting the system into a linear nominal model and an additive perturbation which gathers nonlinearities, parametric uncertainties, and exogenous disturbances, the methodology hereby proposed preserves some nonlinear terms in the nominal system via an exact polytopic representation which leads to design conditions in the form of linear matrix inequalities. As a result, feasible solutions are found where former approaches fail; these solutions have more accurate settling-time estimates with reduced control effort. The corresponding control law includes well-known high-order sliding modes as a particular case. Numerical simulations are provided to illustrate the advantages of the proposal.
Output Global Oscillatory Synchronization of Heterogeneous Systems
International Journal of Control
https://doi.org/10.1080/00207179.2019.1690689
Hafiz Ahmed 1 , Rosane Ushirobira 2 , Denis Efimov 3 , Leonid Fridman Golredich 4 , Yongqiang Wang 5
1 Coventry University, School of Mechanical, Aerospace & Automotive Engineering
2 Inria, Univ. Lille, CNRS, UMR 9189, Centre de Recherche en Informatique Signal et Automatique de Lille
3 Villenueve d'Ascq, Nord Europe Center
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería
5 Clemson Universit, Department of Electrical and Computer Engineering

Keywords: Output synchronisation, sliding mode observation, Van der Pol oscillator, real-time control
Abstract: The global output synchronisation problem for heterogeneous nonlinear systems having relative degree 2 or higher is studied. The proposed approach consists in two steps. First, a partial projection of individual subsystems into the Brockett oscillators is performed using a sliding-mode control. Second, the network of these oscillators is synchronised using the global synchronisation results of a particular second-order nonlinear oscillator model from Ahmed, Ushirobira, and Efimov [(2019). Robust global synchronization of brockett oscillators. IEEE Transactions on Control of Network Systems, 6(1), 289??298]. Our approach is based on output feedback and uses a higher order sliding mode observer to estimate the states and perturbations of the synchronised nonlinear systems. Along with numerical simulations, the performance of the proposed synchronisation scheme is experimentally verified on a network of Van der Pol oscillators.
On the delayed kinematic correspondence with variable time delays for the control of the bilateral teleoperation of robots
International Journal of Control
https://doi.org/10.1080/00207179.2019.1707287
Marco Antonio Arteaga Pérez 1 , Mauro López Rodríguez 1 , Emmanuel Nuño 2 , ?scar Hernández Ortiz 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Guadalajara, Centro Universitario de Ciencias Exactas e Ingeniería

Keywords: Bilateral teleoperators, observer design, variable time delays, delayed kinematic correspondence
Abstract: Bilateral teleoperators allow to perform tasks in remote environments. Telepresence and transparency are affected when delays are present. A proposal is made on the most important cases to deal with for the delayed kinematic correspondence in bilateral teleoperation with variable time delays and a control??observer scheme is proposed. Any of the two manipulators can be moved causing a trajectory tracking in the remote robot. Should the latter get in touch with the environment, the operator gets some degree of delayed kinematic correspondence. Only the mild assumptions are made that human/environment forces and their derivatives are bounded. Experiments are provided.
A Force/Motion Control Approach Based on Trajectory Planning for Industrial Robots With Closed Control Architecture
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3085528
Alejandro Gutiérrez Giles 1 , Luis U. Evangelista Hernández 1 , Marco Antonio Arteaga Pérez 2 , Carlos A. Cruz Villar 1 , Alejandro Rodríguez Angeles 1
1 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Force control, motion control, robot control, robotic assembly, manufacturing automation
Abstract: Most industrial robots are provided by the manufacturer with a controller that cannot be modified by the user (e.g. a standard PID). This arrangement is commonly referred to as closed control architecture, since it is not possible to program arbitrary control laws. For the implementation of novel algorithms, it is on the contrary necessary to employ an open control architecture, which allows programming any control scheme. For that reason, it is customary to have testbeds that are made up of robot manipulators specially designed for this goal. Another disadvantage of the closed control architecture is that the controller provided by the manufacturer usually does not include a force control term since it allows only to program desired motion trajectories. To overcome these drawbacks without physically modifying the closed control architecture, this contribution presents a novel approach to simultaneously follow position and force trajectories by employing only motion planning, i.e. only by choosing the desired position trajectory. The approach is especially well suited for DC motor actuators with large gear reduction ratios as those of many industrial robots. The convergence of the manipulator position and applied force depends exclusively on the performance of the controller provided by the manufacturer. The approach is tested on a dual-arm cooperative manipulation system made up of two ABB IRB-2400 industrial robots with closed control architecture.
Independently Tunable Closely Spaced Triband Frequency Selective Surface Unit Cell Using the Third Resonant Mode of Split Ring Slots
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3100325
Henry Fabian Gongora 1 , Alexander Martynyuk 2 , Jorge Rodríguez Cuevas 2 , Lourdes Martínez López 2 , Rosalba Martínez López 2 , José Ismael Martínez López 2
1 Universidad Autónoma de Campeche, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Frequency selective surfaces, split ring resonators, mutual coupling
Abstract: In this paper, a tunable triband frequency selective surface unit cell based on varactor-loaded split ring slots is presented. By using the third resonant mode, a considerable mutual coupling reduction between adjacent ring slots is obtained ensuring both close band response as well as independent band tuning. Simulated results show the tunable properties of the proposed approach by shifting the three passbands resonant frequencies from 8.368, 10.276, and 12.010 GHz (for the unloaded split ring slots), to 7.732, 9.202, and 10.900 GHz, respectively, when each split ring slot is loaded with a capacitance of 140 fF. Furthermore, the metal shorts that split the ring slots as well as the metal rings located in between the slots are used to build the conducting paths to bias each varactor with minimum disruption in the RF response. A demonstrator based on an X-band diaphragm was designed, fabricated, and experimentally tested. Measured results using a varactor with capacitance range of 30-65 fF show resonant frequencies for the unbiased varactors at 8.53, 9.70 and 11.47 GHz with insertion loss of 1.1, 2.3 and 2.4 dB, respectively, while biasing the diodes at maximum reverse voltages (24 V) provides resonant frequencies at 8.74, 10.03 and 11.77 GHz with insertion loss of 0.8, 1.4 and 1.7 dB, respectively. Frequency shifts of 210, 330 and 300 MHz for the first, second and third resonant frequencies were obtained, respectively. The -10 dB reflection coefficient bandwidths were 495 MHz for the first band, 436 MHz for the second band and 418 MHz for the third band. Close band response is verified obtaining frequency band ratios of 1.18 and 1.14 for the third to the second resonance, and for the second to the first resonance, respectively.
Adjoint slip inversion under a constrained optimization framework: revisiting the 2006 Guerrero slow slip event
Geophysical Journal International
https://doi.org/10.1093/gji/ggab165
Josué Tago Pacheco 1 , Víctor M. Cruz Atienza 2 , Carlos Villafuerte 2 , Takuya Nishimura 3 , Vladimir Kostoglodov 2 , Jorge Real Pérez 2 , Yoshihiro Ito 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 Kyoto University, Disaster Prevention Research Institute

Keywords: Transient deformation, Inverse theory, Numerical modelling
Abstract: To shed light on the prevalently slow, aseismic slip interaction between tectonic plates, we developed a new static slip inversion strategy, the ELADIN (ELastostatic ADjoint INversion) method, that uses the adjoint elastostatic equations to compute the gradient of the cost function. ELADIN is a 2-step inversion algorithm to efficiently handle plausible slip constraints. First it finds the slip that best explains the data without any constraint, and then refines the solution by imposing the constraints through a Gradient Projection Method. To obtain a self-similar, physically consistent slip distribution that accounts for sparsity and uncertainty in the data, ELADIN reduces the model space by using a von Karman regularization function that controls the wavenumber content of the solution, and weights the observations according to their covariance using the data precision matrix. Since crustal deformation is the result of different concomitant interactions at the plate interface, ELADIN simultaneously determines the regions of the interface subject to both stressing (i.e. coupling) and relaxing slip regimes. For estimating the resolution, we introduce a mobile checkerboard analysis that allows to determine lower-bound fault resolution zones for an expected slip-patch size and a given stations array. We systematically test ELADIN with synthetic inversions along the whole Mexican subduction zone and use it to invert the 2006 Guerrero Slow Slip Event (SSE), which is one of the most studied SSEs in Mexico. Since only 12 GPS stations recorded the event, careful regularization is thus required to achieve reliable solutions. We compared our preferred slip solution with two previously published models and found that our solution retains their most reliable features. In addition, although all three SSE models predict an upward slip penetration invading the seismogenic zone of the Guerrero seismic gap, our resolution analysis indicates that this penetration might not be a reliable feature of the 2006 SSE.
Saturated Lipschitz Continuous Sliding Mode Controller for Perturbed Systems With Uncertain Control Coefficient
IEEE Transactions on Automatic Control
https://doi.org/10.1109/TAC.2020.3034872
Carlos Arturo Martínez Fuentes 1 , Richard Seeber 2 , Leonid Fridman Golredich 1 , Jaime Alberto Moreno Pérez 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Graz University of Techonology, Institute of Automation and Control
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Saturation, sliding mode control, uncertain systems
Abstract: In this article, a Lipschitz continuous sliding mode controller (LCSMC) is proposed to stabilize an integrator chain with a saturated control input, Lipschitz continuous perturbations, and an unknown control coefficient. The proposed controller ensures global finite-time convergence to the sliding surface by means of a control signal that is Lipschitz continuous (i.e., has finite gain) and is bounded by a given actuator limit. Stability conditions for the controller's tuning parameters are derived and the effectiveness of the approach is demonstrated in the course of a numerical simulation.
Bluetooth Worm Propagation in Smartphones: Modeling and Analyzing Spatio-Temporal Dynamics
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3081482
Gabriel González 1 , María Elena Lárraga 1 , Luis Agustín Álvarez Icaza 1 , Javier Gómez 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bluetooth devices, cellular automata, discrete-time systems, epidemic model, malware propagation, smartphones, systems modeling, spatiotemporal phenomena
Abstract: The use of smartphones has become an inherent part of daily human life. It allows users to keep personal information, emails, pictures, social media accounts, and financial data in one place. Consequently, smartphones are an attractive target for malware developers to spread malicious content, aiming at extracting information without the user's knowledge. Therefore, understanding malware propagation characteristics could provide a means to evaluate how they behave in order to plan security solutions accordingly. Bluetooth antennas are a channel for spreading malware through smartphones, where the probability of infection, similar to biological viruses, depends mainly on the attacker's physical proximity. This work presents a model based on cellular automata and epidemiological compartmental models for studying the spatial and temporal propagation of Bluetooth worms in smartphones. The proposed model incorporates the individual characteristics of each device, such as security settings, latency time, operating system, different classes of Bluetooth antennas (range and transfer rate), and different user mobility patterns. Several simulation scenarios are analyzed in order to study the spreading dynamics of Bluetooth-based worms, considering the location where the outbreak begins, and the different types of antennas integrated into the smart devices. Simulation results indicated that the proposed model is appropriate for studying how the users' demographics affect the worm's propagation dynamics in time and space. Moreover, the model permits an analysis of the impact of users' awareness about the risks inherent in using smart devices in Bluetooth networks, based on the acceptance of incoming communication and the effects of recovery and immunity to threats. Finally, the proposed model preserves simplicity and computational efficiency, with the possibility of extending beyond Bluetooth in order to include other transmission media.
Small-signal Model for Dual-active-bridge Converter Considering Total Elimination of Reactive Current
Journal of Modern Power Systems and Clean Energy
https://doi.org/10.35833/MPCE.2018.000911
Juan Ramón Rodríguez Rodríguez 1 , Nadia Maria Salgado Herrera 2 , Jacinto Torres Jiménez 3 , Néstor González Cabrera 1 , David Granados Lieberman 4 , Martin Valtierra Rodriguez 5
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Energías Renovables
3 Instituto Tecnológico Superior de Irapuato
4 Instituto Tecnológico Superior de Irapuato, Facultad de Ingeniería Electromecanica
5 Universidad Autónoma de Querétaro, Facultad de Ingeniería campus San Juan del Río.

Keywords: Small-signal modal (SSM), dual-active-bridge (DAB) converter, reactive current elimination, proportional integral (PI) control.
Abstract: Emerging technologies such as electric vehicles, sol-id-state transformers, and DC transformers are implemented using the closed-loop bi-directional dual-active-bridge (DAB) converter. In this context, it is necessary to have average models that provide an efficient way of tuning the proportional integral (PI) compensator parameters for large- and small-signal applications. We present a novel small-signal model (SSM) for DAB converter with a single closed-loop PI controller and the total elimination of reactive current (I Q =0). The method applies a modulation technique for I Q =0 and introduces a composite function in the controller while reducing the original nonlinear switching model, which allows to decrease the order of the transfer function and analyze the closed-loop operation. The proposed SSM is analyzed using different response time, load, and DC voltage changes. The simulation and experimental results demonstrate the ease of implementation and effectiveness of the proposed model with respect to other SSM techniques.
Power System Coherency Detection from Wide-Area Measurements by Typicality-Based Data Analysis
IEEE Transactions on Power Systems
https://doi.org/10.1109/TPWRS.2021.3088261
Lucas Lugnani 1 , Mario Roberto Arrieta Paternina 2 , Daniel Dotta 1 , Joe H. Chow 3 , Yilu Liu 4
1 University of Campinas, Department of Electrical Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering
4 University of Tennessee, Department of Electrical Engineering

Keywords: Coherency, clustering, data-driven, WAMS, statistical typicality
Abstract: This paper presents a new data-driven methodology for power system coherency identification of generator and non-generator buses. This methodology is exclusively based on intrinsic statistical properties extracted directly from observations, without any prior assumption of the probability distribution function (PDF) for the data. The main advances of this proposal are: ( i ) gathering of statistical information from the data itself despite scenarios where the PDF may change (different inverter-based load and generation scenarios, load levels of the system, and changes in topology); and ( ii ) assignment of buses into coherent areas without any tuning of parameters, nor manually labeling of huge amounts of training data. This new method, called typicality-based data analysis (TDA), is applied to the correlation metric of the distance between dynamic responses of buses, either voltage angles or frequencies. Simulated signals from a benchmark power system with cases considering the presence of non-synchronous generation and islanding conditions, and real data associated with generation trips in the U.S. Eastern Interconnection are used to corroborate the methodology effectiveness.
Índice de bloqueo para mejorar la protección diferencial de secuencia negativa de transformadores utilizando ATP/EMTP
Ingeniería Investigación y Tecnología
https://doi.org/10.22201/fi.25940732e.2021.22.1.001
Daniel Guillen 1 , Vicente Torres García 2 , Juan Carlos Olivares Galván 3
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Departamento de Energía

Keywords: Corrientes de magnetización, fallas internas, secuencia negativa, protección diferencial, relevador de ángulo de operación, transformador de potencia.
Abstract: En este trabajo se presenta un nuevo índice de bloqueo para mejorar el rendimiento de la protección diferencial del transformador basado en la secuencia negativa. Para garantizar la confiabilidad de cualquier red eléctrica, los esquemas de protección son una tarea primordial. Particularmente, los transformadores de potencia están sujetos a eventos transitorios de falla y no falla, tales como fallas entre espiras, corrientes de magnetización y sobreexcitación. En consecuencia, la protección del transformador debe funcionar correctamente bajo fenómenos transitorios. Para analizar las fallas internas y algunos eventos transitorios en transformadores, se implementa una protección diferencial de secuencia negativa mediante el uso del software ATP/EMTP. El esquema propuesto emplea un esquema de protección diferencial (87Q), el cual se basa principalmente en la diferencia angular entre secuencias negativas de las corrientes primarias y secundarias utilizando un relevador de ángulo de operación (ROA). Esta propuesta de protección introduce un índice de bloqueo para evitar el mal funcionamiento durante la energización del transformador, ya que se ha reportado que el ROA puede presentar un mal funcionamiento durante eventos transitorios. El nuevo índice introducido representa una distancia entre secuencias durante el período transitorio, lo que ayuda a discriminar las fallas internas de las corrientes de energización. En este sentido, los autores presentan una evaluación del índice de bloqueo introducido para evitar el mal funcionamiento, especialmente cuando la protección diferencial está funcionando en condiciones desbalanceadas, o en condiciones transitorias, como la corriente de energización. Con base en los resultados, la propuesta muestra un buen desempeño y su efectividad es demostrada bajo diferentes escenarios de falla.
Fault location on transmission lines based on travelling waves using correlation and MODWT
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2021.107308
Víctor Hugo González Sánchez 1 , Vicente Torres García 1 , Daniel Guillen 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias

Keywords: Fault location, transmission lines, traveling waves, correlation, MODWT, transients
Abstract: This paper presents a protection scheme for alternating current transmission lines based on the traveling wave propagation. The analyzed protection scheme uses measurements in only one terminal by using the distributed parameter theory. The method analyzes the fault location using the correlation between two traveling waves, backward and forward waves. Results demonstrate that the correlation method can accurately estimate the fault distance, and this is carried out by using the first two wavefronts of the arrived signals at the measurement terminal. The algorithm is validated through the IEEE 9-bus test system, considering different faults simulated in the software ATP-EMTP. The studied method??s effectiveness is assessed and compared with the MODWT, showing both techniques good results for the fault location process.
A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids
Mathematics
https://doi.org/10.3390/math9131474
Rubén Tapia Olvera 1 , Francisco Beltran Carbajal 2 , Antonio Valderrabano González 3 , Omar Aguilar Mejía 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
3 Universidad Panamericana, Facultad de Ingeniería
4 Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados

Keywords: B-spline neural networks, adaptive power system control, coordinated multiple controllers, StatCom
Abstract: This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers?? gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers?? gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.
Adaptive Robust Motion Control of Quadrotor Systems Using Artificial Neural Networks and Particle Swarm Optimization
Mathematics
https://doi.org/10.3390/math9192367
Hugo Yáñez Badillo 1 , Francisco Beltran Carbajal 2 , Rubén Tapia Olvera 3 , Antonio Favela Contreras 4 , Carlos Sotelo 4 , David Sotelo 4
1 Tecnológico de Estudios Superiores de Tianguistenco, Departamento de Investigación
2 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias

Keywords: Quadrotor UAV, artificial neural networks, robust control, Taylor series, B-splines, particle swarm optimization
Abstract: Most of the mechanical dynamic systems are subjected to parametric uncertainty, unmodeled dynamics, and undesired external vibrating disturbances while are motion controlled. In this regard, new adaptive and robust, advanced control theories have been developed to efficiently regulate the motion trajectories of these dynamic systems while dealing with several kinds of variable disturbances. In this work, a novel adaptive robust neural control design approach for efficient motion trajectory tracking control tasks for a considerably disturbed non-linear under-actuated quadrotor system is introduced. Self-adaptive disturbance signal modeling based on Taylor-series expansions to handle dynamic uncertainty is adopted. Dynamic compensators of planned motion tracking errors are then used for designing a baseline controller with adaptive capabilities provided by three layers B-spline artificial neural networks (Bs-ANN). In the presented adaptive robust control scheme, measurements of position signals are only required. Moreover, real-time accurate estimation of time-varying disturbances and time derivatives of error signals are unnecessary. Integral reconstructors of velocity error signals are properly integrated in the output error signal feedback control scheme. In addition, the appropriate combination of several mathematical tools, such as particle swarm optimization (PSO), Bézier polynomials, artificial neural networks, and Taylor-series expansions, are advantageously exploited in the proposed control design perspective. In this fashion, the present contribution introduces a new adaptive desired motion tracking control solution based on B-spline neural networks, along with dynamic tracking error compensators for quadrotor non-linear systems. Several numeric experiments were performed to assess and highlight the effectiveness of the adaptive robust motion tracking control for a quadrotor unmanned aerial vehicle while subjected to undesired vibrating disturbances. Experiments include important scenarios that commonly face the quadrotors as path and trajectory tracking, take-off and landing, variations of the quadrotor nominal mass and basic navigation. Obtained results evidence a satisfactory quadrotor motion control while acceptable attenuation levels of vibrating disturbances are exhibited.
Thermoelectromagnetic Lumped-Parameter Model of High Temperature Superconductor Generators for Transient Stability Analysis
IEEE Transactions on Applied Superconductivity
https://doi.org/10.1109/TASC.2021.3060696
Alejandro Baez Muñoz 1 , Frédéric Trillaud Pighi 2 , Juan Ramón Rodríguez Rodríguez 1 , Luis Miguel Castro González 1 , Rafael Escarela Pérez 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: HTS hybrid synchronous generator, thermo-electromagnetic model, three-phase short circuit, transient stability
Abstract: A refined dynamic lumped-parameter model of a REBCO field coil synchronous generator including details of the thermoelectromagnetic phenomenology of the superconductor has been developed in the classic dq0 frame of reference. The idea is to build a generic modelling framework that can be used in power systems engineering studies to infer trends on the behavior of HTS field coil machines in power grids. In the present work, the transient stability of a hybrid High Temperature Superconducting (HTS) generator is analyzed under the most severe operating condition applying a three-phase short circuit at its terminals. For the study, we chose the parameters of a wind generator at 1 MW. Two cases are considered: 1) no full transition of the HTS to the normal-resistive state under stable condition, 2) full transition of the HTS under unstable condition. The response of the HTS machine is compared against that of a conventional machine.
Cross phases hybrid transformer for managing and improving the energy quality
International Journal of Electrical Power & Energy Systems
https://doi.org/10.1016/j.ijepes.2021.107005
M. Díaz Ojeda 1 , Juan Ramón Rodríguez Rodríguez 1 , J. Hernández Sánchez 1 , Frédéric Trillaud Pighi 2 , Juan Carlos Olivares Galván 3 , Rafael Escarela Pérez 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Autónoma Metropolitana, Departamento de Energía
4 Universidad Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: Hybrid distribution transformer, Cross phases connection, Power electronics, H-bridge, Power quality, Dq0 control
Abstract: The presence of harmonic currents in three-phase distribution networks and the stochastic behavior of unbalanced loads with different power factors are undoubtedly responsible for power quality problems. This paper proposes a novel solution named Cross Phases Hybrid Transformer (CPHT) to address those issues. The CPHT incorporates a conventional distribution transformer into an AC/AC power electronic stage referred to as cross phase module. This new hardware configuration allows to achieve continuous three-phase energy supply of distinct loads as well as high energy quality indexes for diverse distribution networks. The proposed solution has been numerically and experimentally validated by means of simulations carried out in Simulink and with a scaled-down laboratory prototype respectively. The validations consider distinct case studies to show the operative advantages of the CPHT with respect to other topologies reported in the literature.
Coordinated Optimal Volt/Var Control for Distribution Networks via D-PMUs and EV Chargers by Exploiting the Eigensystem Realization
IEEE Transactions on Smart Grid
https://doi.org/10.1109/TSG.2021.3050443
Gabriel E. Mejía Ruiz 1 , Romel Ángel Cárdenas Javier 1 , Mario Roberto Arrieta Paternina 1 , Juan Ramón Rodríguez Rodríguez 1 , Juan Manuel Ramírez Arredondo 2 , Alejandro Zamora Méndez 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica

Keywords: Distribution grids, Volt/Var control, optimal control, eigensystem realization algorithm, electrical vehicle chargers, distribution phasor measurement units
Abstract: This article proposes a novel optimal hybrid control framework to improve the voltage profile of highly unbalanced Distribution Grids (DGs) by coordinating the injection of reactive power from multiple off-board Electrical Vehicles (EVs) chargers. It exploits the time-synchronized measurements advantages, centralized control, and local controllers embedded into a hierarchical and scalable scheme, coordinated by the distribution system operator (DSO). The proposed framework is aimed to increase the modern electrical networks' flexibility, reliability, and stability. It is powered by the Eigensystem Realization (ER)-based system identification technique, a Linear Quadratic Gaussian (LQG) controller, the Distribution-level Phasor Measurement Units (D-PMUs), and a new aggregator agent that handles the EV chargers power injection to precisely and timely regulate the dynamic voltage response in a sub-area or the entire DG. The robustness and feasibility of the proposal are demonstrated by employing simulated scenarios with unbalanced faults, latency in communications, and highly unbalanced loads conditions on the IEEE 13 and 123 nodes test feeders, compensating the voltage variations accurately in less than 205 ms. The promising outcome of this study suggests a novel application for an emerging measurement-based control system in the operation of modern active DGs.
On the Improvement of representative demand curves via a hierarchical agglomerative clustering for power transmission network investment
Energy
https://doi.org/10.1016/j.energy.2021.119989
Néstor González Cabrera 1 , José Ortiz Bejar 2 , Alejandro Zamora Méndez 3 , Mario Roberto Arrieta Paternina 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Michoacana de San Nicolás de Hidalgo
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica

Keywords: Transmission expansion planning, Hierarchical agglomerative clustering, Elbow rule, Linkage criterion, High-dimensionality data, K-means
Abstract: This paper introduces an optimal clustering-based strategy to gain representative demand curves from hourly demand data that allow determining the power transmission network investment by solving the transmission expansion planning (TEP) problem. The proposed approach also provides a high-dimensionality data optimal reduction for the representative demand curves that feed the TEP problem. The key idea behind this strategy is to extract demand patterns from the electric power system demand data through the implementation of a hierarchical agglomerative clustering algorithm (HACA) based on the Elbow??s rule and a linkage criterion, such as Ward??s variance. Then, a 24-h demand pattern is provided by following three different grouping strategies: seasonal, monthly, and weekly. As a second stage, this strategy includes the TEP formulation together with the transmission losses?? linearised model aiming to test the representative demand curves achieved by HACA. To illustrate the efficiency, application, and superior functionality of the proposal, this is implemented over the IEEE 118-node network under several case studies. To determine the most appropriate approach, the results are compared with the well-known K-means method.
Security constrained OPF for AC/DC systems with power rescheduling by power plants and VSC stations
Sustainable Energy, Grids and Networks
https://doi.org/10.1016/j.segan.2021.100517
Juan S. Guzmán Feria 1 , Luis Miguel Castro González 1 , Néstor González Cabrera 1 , José Horacio Tovar Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Morelia, Posgrado en Ingeniería Eléctrica

Keywords: AC/DC systems, HVDC links, Linear programming, Power rescheduling, Security constrained OPF, VSC units
Abstract: This paper describes a novel modelling framework for security constrained optimal power flows (SCOPF) aimed at multi-terminal VSC-based AC/DC systems, where power rescheduling by power plants and converters is considered by means of voltage/power droop controls. The optimisation method is based on a linear programming model where generation cost curves and AC/DC power losses are included by piecewise linear functions. The formulation accommodates arbitrary network models with numerous VSC-connected AC grids. This leads to a suitable modelling flexibility for corrective SCOPF analysis of practical AC/DC grids formed by VSC-based transmission grids. The proposed SCOPF formulation enables efficient contingency analysis involving the disconnection of AC branches, DC lines, power plants, and VSC units. This is confirmed using an AC/DC grid with four VSC-connected AC systems. Simulation results show that this new method presents average errors inferior to 5% whereas computing times are reduced by more than 90% with respect to a nonlinear SCOPF method based on sequential quadratic programming. The practicality of the proposed method is also proven by studying an AC/DC system comprising seven VSC-coupled AC grids totalling seventy dispatchable generators.
Advanced PET Control for Voltage Sags Unbalanced Conditions Using Phase-Independent VSC-Rectification
IEEE Transactions on Power Electronics
https://doi.org/10.1109/TPEL.2021.3068627
Alfredo Velázquez Ibáñez 1 , Juan Ramón Rodríguez Rodríguez 1 , Mario A. Santoyo Anaya 2 , Mario Roberto Arrieta Paternina 1 , Vicente Torres García 1 , Edgar Lenimirko Moreno Goytia 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación

Keywords: AC??DC??AC, dual active bridge (DAB), power conversion, power electronic transformer, unbalanced control, unbalanced input voltages, voltage sags, voltage source converter (VSC)
Abstract: The power electronic transformer (PET) is an emerging technology that is quickly becoming a key component of the next-to-come power distribution networks (PDNs), due to its versatility on energy management, as well as, the improvement on the quality of the energy. PDNs are characterized by their unbalanced conditions, causing that PETs driven by conventional dq0 controls introduce current distortions on the primary winding of the transformer. Such distortion is evidenced in the 2 ω oscillations of Vd and Vq acting as harmonic sources. In this sense, this article proposes a novel control approach for PETs. The key idea behind of this proposal consists of operating each phase independently, which is achieved through the enclosed rectification and the mitigation of the 2 ω oscillations in a dual active bridge topology. The attained advantages by this control scheme are: a) balancing of the primary winding currents; b) unitary power factor; c) negligible harmonic distortion; and d) 2 ω oscillation mitigation on the dc bus.
Two effective methods for impedance estimation in distance relays based on the DC offset removal
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2021.107102
Alejandro Zamora Méndez 1 , Julian Sotelo Castañón 2 , Mario Roberto Arrieta Paternina 3 , Paola Buendia 3 , Cristian Torres 3 , Carlos Toledo Santos 4 , Víctor Velasco 3 , Francisco Zelaya 5 , Gabriel E. Mejía Ruiz 3
1 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
2 Universidad de Guadalajara, Facultad de Ingeniería Mecánica y Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Industrial de Santander
5 University of Tennessee

Keywords: Eigensystem realization algorithm, Z-domain, Phasor estimation, Distance relay, Impedance estimation, DC offset
Abstract: This paper introduces the eigensystem realization (ER)-based identification algorithm and the Z-domain method (ZDM) to improve the impedance estimation of transmission lines under fault conditions, which is achieved by removing the exponential decaying DC offset from current signals in distance relays. Both methods effectively work employing a one-cycle rectangular window; specifically, the Z-domain method works in less than a fifth of one-cycle window, ensuring timely, accurate, and prompt estimates. To confirm the effectiveness and performance of the proposed algorithms, they are evaluated under steady-state and dynamic conditions by using time-domain simulations performed in PSCAD©and DIgSILENT©PowerFactory. They also are compared with the well-known discrete Fourier transform (DFT). The attained results indicate that both the ER-based and Z-domain methods can become a powerful tool to reduce the adverse influence of exponentially decaying DC offsets in distance relays.
Risk Analysis of Cavitation in Hydraulic Structures
World Journal of Engineering and Technology
https://doi.org/10.4236/wjet.2021.93043
Gabriel Echávez Aldape 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cavitation, Spillways, Damages, High Head, Risk Analysis, Surface Roughness
Abstract: Damages as a result of cavitation are ever existing problems in high-head spillways. This article presents a brief introduction to the problems associated with high-head spillways and describes a procedure that takes into account the flow near the chute surface where the phenomenon occurs, instead of the mean flow. Application of risk analysis methodology presented can be used to estimate whether there is a possibility of cavitation or there is necessity to determine where the first aereator should be located. The advantage of the procedure herein presented takes into consideration an important new variable, such as the surface roughness. In addition, emphasis should be placed first on the need to investigate other high-head dams which climate change may have exposed them to this kind of damages. Second, there is a need to make measurement in prototype. Finally, to underscore the importance of these problems, a comment is made concerning the Oroville Dam contingency in the state of California, (United States).
Improving DFT-Based Image Watermarking Using Particle Swarm Optimization Algorithm
Mathematics
https://doi.org/10.3390/math9151795
Manuel Cedillo Henández 1 , Antonio Cedillo Hernández 2 , Francisco Javier García Ugalde 3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Instituto Tecnológico de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: robust watermarking; information security; spread spectrum; ownership authentication; image processing; particle swarm optimization
Abstract: Robust digital image watermarking is an information security technique that has been widely used to solve several issues related mainly with copyright protection as well as ownership authentication. In general terms, robust watermarking conceals a small signal called a ??watermark? in a host image in a form imperceptible to human vision. The efficiency of conventional robust watermarking based on frequency domain depend directly on the results of performance in terms of robustness and imperceptibility. According to the application scenario and the image dataset, it is common practice to adjust the key parameters used by robust watermarking methods in an experimental form; however, this manual adjustment may involve exhaustive tasks and at the same time be a drawback in practical scenarios. In recent years, several optimization techniques have been adopted by robust watermarking to allowing adjusting in an automatic form its key operation parameters, improving thus its performance. In this context, this paper proposes an improved robust watermarking algorithm in discrete Fourier transform via spread spectrum, optimizing the key operation parameters, particularly the amounts of bands and coefficients of frequency as well as the watermark strength factor using particle swarm optimization in conjunction with visual information fidelity and bit correct rate criteria. Experimental results obtained in this research show improved robustness against common signal processing and geometric distortions, preserving a high visual quality in color images. Performance comparison with conventional discrete Fourier transform proposal is provided, as well as with the current state-of-the-art of particle swarm optimization applied to image watermarking.
Additional Information Delivery to Image Content via Improved Unseen??Visible Watermarking
Electronics
https://doi.org/10.3390/electronics10182186
Oswaldo Ulises Juárez Sandoval 1 , Laura Josefina Reyes Ruiz 1 , Francisco Javier García Ugalde 1 , Manuel Cedillo Henández 2 , Jazmin Ramírez Hernández 2 , Robert Morelos-Zaragoza Ascanio 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 San Jose State University, College of Engineering

Keywords: invisible??visible watermarking; unseen??visible watermarking; imperceptible??visible watermarking; watermark complement strategy; visual degradation; histogram distortion; QR code
Abstract: In a practical watermark scenario, watermarks are used to provide auxiliary information; in this way, an analogous digital approach called unseen??visible watermark has been introduced to deliver auxiliary information. In this algorithm, the embedding stage takes advantage of the visible and invisible watermarking to embed an owner logotype or barcodes as watermarks; in the exhibition stage, the equipped functions of the display devices are used to reveal the watermark to the naked eyes, eliminating any watermark exhibition algorithm. In this paper, a watermark complement strategy for unseen??visible watermarking is proposed to improve the embedding stage, reducing the histogram distortion and the visual degradation of the watermarked image. The presented algorithm exhibits the following contributions: first, the algorithm can be applied to any class of images with large smooth regions of low or high intensity; second, a watermark complement strategy is introduced to reduce the visual degradation and histogram distortion of the watermarked image; and third, an embedding error measurement is proposed. Evaluation results show that the proposed strategy has high performance in comparison with other algorithms, providing a high visual quality of the exhibited watermark and preserving its robustness in terms of readability and imperceptibility against geometric and processing attacks.
Imperceptible-Visible Watermarking to Information Security Tasks in Color Imaging
Mathematics
https://doi.org/10.3390/math9192374
Oswaldo Ulises Juárez Sandoval 1 , Francisco Javier García Ugalde 1 , Manuel Cedillo Henández 2 , Jazmin Ramírez Hernández 2 , Leobardo Hernández Gonzalez 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: invisible-visible watermarking; imperceptible-visible watermarking; unseen-visible watermarking; QR; histogram binarization function
Abstract: Digital image watermarking algorithms have been designed for intellectual property, copyright protection, medical data management, and other related fields; furthermore, in real-world applications such as official documents, banknotes, etc., they are used to deliver additional information about the documents?? authenticity. In this context, the imperceptible??visible watermarking (IVW) algorithm has been designed as a digital reproduction of the real-world watermarks. This paper presents a new improved IVW algorithm for copyright protection that can deliver additional information to the image content. The proposed algorithm is divided into two stages: in the embedding stage, a human visual system-based strategy is used to embed an owner logotype or a 2D quick response (QR) code as a watermark into a color image, maintaining a high watermark imperceptibility and low image-quality degradation. In the exhibition, a new histogram binarization function approach is introduced to exhibit any watermark with enough quality to be recognized or decoded by any application, which is focused on reading QR codes. The experimental results show that the proposed algorithm can embed one or more watermark patterns, maintaining the high imperceptibility and visual quality of the embedded and the exhibited watermark. The performance evaluation shows that the method overcomes several drawbacks reported in previous algorithms, including geometric and image processing attacks such as JPEG and JPEG2000.
Jarosite dissolution kinetics in the presence of acidic thiourea and oxalate media
Hydrometallurgy
https://doi.org/10.1016/j.hydromet.2021.105565
Dandy Calla Choque 1 , Gretchen Lapidus Lavine 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Departamento de Ingeniería de Procesos e Hidráulica

Keywords: Jarosite, Silver leaching, Thiourea, Oxalate
Abstract: This work explores the effect of temperature and pH on the decomposition and leaching of a heterogeneous particle size (d80 = 24 μm) industrial jarosite composed mainly of natrojarosite in an acid medium. The kinetic study of the decomposition process and of the leaching reaction was determined by fitting the data to the multiparticulate shrinking core model. The results of the adjustment indicated that the controlling phenomenon was the heterogeneous decomposition reaction, which was consistent with the activation energy (43??44 KJ mol??1) for pH values between 1 and 2, indicating that the silver dissolution reaction is the controlling factor in this system.
Mass transport by an oscillatory electroosmotic flow of power-law fluids in hydrophobic slit microchannels
Journal of the Brazilian Society of Mechanical Sciences and Engineering
https://doi.org/10.1007/s40430-020-02746-z
R. D. Baños 1 , José Carlos Arcos Hernández 1 , Oscar Eladio Bautista Godínez 1 , Federico Méndez Lavielle 2 , E. A. Merchán Cruz 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Power-law fluids, Slippage, Oscillatory electroosmotic flow, Mass transport rate, Microchannel
Abstract: In this work, we study the hydrodynamics, concentration field, and mass transport of species due to an oscillatory electroosmotic flow that obeys a power law. An additional aspect that is considered in the analysis corresponds to the effect of the slippage condition at the walls of the microchannel. The governing equations that describe the involved phenomena are the following: equation of Poisson??Boltzmann for the electrical potential in the electric double layer, the momentum equation, and the species transport equation. These equations were simplified with the aid of the lubrication theory and were numerically solved by using a conventional finite difference scheme. Our results suggest that, under the slippage effects, the best conditions can be promoted for the mass transport of species for different values of the Schmidt number and Womersley numbers less than unity, and even it is maximized up to two orders of magnitude when Wo>1. In the analysis, the cross-over phenomenon appears for the mass transport for different species and it is identified for both Newtonian and non-Newtonian fluids. For shear-thinning fluids with slippage at the microchannel walls, the cross-over phenomenon occurs, and the species with less diffusivity can be transported up to ten times faster in comparison with Newtonian fluids when the no-slip effect is considered.
CW and Modulated Input Second Harmonic Injection for Efficiency Enhancement in Broadband Power Amplifiers
Electronics
https://doi.org/10.3390/electronics10202507
Chang Hsiu Chen 1 , Patrick Roblin 1 , Yunsik Hahn 1 , José Ismael Martínez López 2 , Chenyu Liang 1
1 The Ohio State University, Department of Electrical and Computer Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Broadband power amplifier, broadband diplexer, efficiency enhancement, input second-harmonic injection
Abstract: The second-harmonic input impedance plays a critical role on the performance of GaN power amplifiers. In a recent paper, a drain efficiency enhancement for a continuous-mode power amplifiers was reported to be achieved using active broadband second-harmonic injection at the PA input. In this paper, the strategy for selecting the second-harmonic input impedance and the necessity for using active injection in such broadband PAs are discussed in detail. Additionally, the methodology for designing an embedded broadband diplexer in the input matching network is reported. Finally, the importance of the phase of the second-harmonic signal injected is demonstrated for both CW and modulated signals using both simulation and measurement, respectively. The effectiveness of the CW and modulated active second-harmonic injection methodology presented here are validated by previously reported measurements that demonstrated an average drain efficiency improvement of 9.4% from 1.3 to 2.4 GHz for CW signals and of 9.7% at 2 GHz for a frequency-modulated 30 MHz chirp radar signal.
A Framework for Analyzing Neighbor Discovery Protocols under Non-Ideal Conditions
Sensors
https://doi.org/10.3390/s21206822
José Jaime Camacho Escoto 1 , Eduardo López Bolaños 2 , Oscar Arana 2 , Javier Gómez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigación en Matemáticas Aplicadas y Sistemas

Keywords: Neighbor discovery, reliability, sensors, IoT
Abstract: Neighbor Discovery (ND) protocols are crucial to achieving the paradigm of interconnecting thousands of small nodes (sensors or things) to the Internet, also known as the IoT. These protocols usually assume that nodes operate with few energy resources. Therefore, they cannot be fully active all the time. The vast majority of these protocols focus on increasing the probability that two nodes become active simultaneously, thus enabling mutual discovery. In addition, these protocols assume that successful discovery is guaranteed once two nodes are simultaneously active, with very few exceptions. However, many problems can disrupt the discovery, such as channel errors, collisions, synchronization mismatches, energy availability, and so forth. Most ND protocols did not consider these factors, making them vulnerable to severe performance degradation when transmission errors occur. This paper proposes a new framework to evaluate the performance of deterministic neighbor discovery protocols when transmission errors are present. The proposed framework facilitates obtaining an analytical CDF of the discovery time of such protocols with transmissions errors without having to implement the protocol in a simulator, since is time-consuming and prone to implementation errors. We applied the framework to analyze the effect of transmission errors on the discovery time in four of the most representative ND protocols in the literature. Finally, we validate the framework accuracy for the selected protocols using extensive simulations. The results show that the CDF of discovery times provided by the framework closely matches the performance results obtained through simulating these protocols. In general, neighbor discovery protocols are deeply affected as a result of transmission errors.
A Propagation Study of LoRa P2P Links for IoT Applications: The Case of Near-Surface Measurements over Semitropical Rivers
Sensors
https://doi.org/10.3390/s21206872
Amado Gutiérrez Gómez 1 , Víctor Rangel Licea 1 , Robert Edwards 2 , John G. Davis 2 , Raúl Aquino Santos 3 , Jesús López De la Cruz 4 , Oliver Mendoza Cano 4 , Miguel López Guerrero 5 , Yu Geng 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Loughborough University, 5G Research Centre
3 Universidad de Colima, Facultad de Telemática
4 Universidad de Colima, Facultad de Ingeniería Civil
5 Universidad Autónoma Metropolitana, Unidad Iztapalapa

Keywords: Chirp modulation, internet of things, path loss
Abstract: Internet of Things (IoT) radio networks are becoming popular in several scenarios for short-range applications (e.g., wearables and home security) and medium-range applications (e.g., shipping container tracking and autonomous farming). They have also been proposed for water monitoring in flood warning systems. IoT communications may use long range (LoRa) radios working in the 915 MHz industrial, scientific and medical (ISM) band. In this research, we study the propagation characteristics of LoRa chirp radio signals close to and over water in a tropical meadow region. We use as a case study the Colima River in Mexico. We develop a novel point-to-point IoT measurement sounding system that does not require decoding of LoRa propriety bursts and provides accurate power versus distance profiles along the riparian zone of a steeply dropping mountain river. We used this system to obtain the measurements reported in this work, which are also analyzed and modeled. The results show that the LoRa signal propagation over water exhibits a log-normal distribution. As a result of the chirp signal processing, two new experimental path loss models are presented. The path loss results show a considerable degradation of the received signal power over water within vegetation and less signal degradation at antenna heights closer to the water surface.
Robust orbital stabilization: A Floquet theory??based approach
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5738
Christian Fredrik Sætre 1 , Anton S. Shiriaev 1 , Leonid Freidovich 2 , Sergei V. Gusev 3 , Leonid Fridman Golredich 4
1 NTNU, Department of Engineering Cybernetics
2 Umea University, Robotics and Control Laboratory
3 Sirius University of Science and Technology, Department of Information Technologies and AI
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Orbital stabilization, robust nonlinear control, sliding mode control, underactuated mechanical systems
Abstract: The design of robust orbitally stabilizing feedback is considered. From a known orbitally stabilizing controller for a nominal, disturbance-free system, a robustifying feedback extension is designed utilizing the sliding-mode control (SMC) methodology. The main contribution of the article is to provide a constructive procedure for designing the time-invariant switching function used in the SMC synthesis. More specifically, its zero-level set (the sliding manifold) is designed using a real Floquet??Lyapunov transformation to locally correspond to an invariant subspace of the Monodromy matrix of a transverse linearization. This ensures asymptotic stability of the periodic orbit when the system is confined to the sliding manifold, despite any system uncertainties and external disturbances satisfying a matching condition. The challenging task of oscillation control of the underactuated cart??pendulum system subject to both matched- and unmatched disturbances/uncertainties demonstrates the efficacy of the proposed scheme.
Robust exact differentiators with predefined convergence time
Automatica
https://doi.org/10.1016/j.automatica.2021.109858
Richard Seeber 1 , Hernan Haimovich 2 , Martin Horn 1 , Leonid Fridman Golredich 3 , Hernán De Battista 4
1 Graz University of Techonology, Institute of Automation and Control
2 Centro Internacional Franco-Argentino de Ciencias de la Información y de Sistemas, CONICET-UNR
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto LEICI, Grupo de Control Aplicado

Keywords: Sliding modes, Super-twisting algorithm, Finite-time convergence, Fixed-time convergence, Disturbance rejection
Abstract: The problem of exactly differentiating a signal with bounded second derivative is considered. A class of differentiators is proposed, which converge to the derivative of such a signal within a fixed, i.e., a finite and uniformly bounded convergence time. A tuning procedure is derived that allows to assign an arbitrary, predefined upper bound for this convergence time. It is furthermore shown that this bound can be made arbitrarily tight by appropriate tuning. The usefulness of the procedure is demonstrated by applying it to the well-known uniform robust exact differentiator, which is included in the considered class of differentiators as a special case.
Texture Analysis of Dried Droplets for the Quality Control of Medicines
Sensors
https://doi.org/10.3390/s21124048
Yojana Carreón 1 , Orlando Díaz Hernández 1 , Gerardo J. Escalera Santos 1 , Iván Cipriano Urbano 2 , Francisco Javier Solorio Ordaz 3 , Jorge González Gutiérrez 3 , Roberto Zenit 4
1 Universidad Autónoma de Chiapas, Facultad de Ciencias en Física y Matemáticas
2 Universidad Autónoma de Coahuila, Escuela de Medicina
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Brown University, School of Engineering

Keywords: Quality control, medicines texture analysis, dried droplets
Abstract: The quality control of medicines guarantees the effectiveness of treatments for diseases. We explore the use of texture analysis of patterns in dried droplets as a tool to readily detect both impurities and changes in drug concentration. Four types of medicines associated with different routes of administration were analyzed: Methotrexate, Ciprofloxacin, Clonazepam, and Budesonide. We use NaCl and a hot substrate at 63 ??C to promote aggregate formation and to reduce droplet drying time. Depending on the medicine, optical microscopy reveals different complex aggregates such as circular to oval splatters, fern-like islands, crown shapes, crown needle-like and bump-like patterns as well as dendritic branched and star-like crystals. We use some physical features of the stains (as the stain diameter and superficial area) and gray level co-occurrence matrix (GLCM) to characterize patterns of dried droplets. Finally, we show that structural analysis of stains can achieve 95% accuracy in identifying medicines with 30% water dilution, while it achieves 99% accuracy in detecting drugs with 10% other substances.
Structural dynamics of a 3 DOF parallel kinematic machine
Ingeniería Investigación y Tecnología
https://doi.org/10.22201/fi.25940732e.2021.22.2.013
Ricardo Yáñez Valdez 1 , Ángel Iván Luna Díaz 1 , Jorge Jayr Cos Díaz 1 , Francisco Cuenca Jiménez 1 , Fernando Velázquez Villegas 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cutting force, dynamic stiffness, natural frequency, parallel kinematic machine, vibration analysis
Abstract: Milling is an intrinsically interrupted cutting operation; therefore, vibrations occur. There are both self-excited (chatter) and forced vibration. Vibrations in milling appear due to the lack of dynamic stiffness of some components in the machine tool-tool-workpiece system. If the vibrations are excessive, the machine stability is negatively affected. In this paper a parallel kinematic machine is modelled and structurally analyzed, considering vibrational parameters (mass, inertia, stiffness, and damping). Theoretical results are used to verify the model. The proposed model provides an effective guide to design milling machines with the best structural arrangement (architecture) and enhancing performance. The value of this finding is in answering the research question: ??Should the machine tool-tool-workpiece system be kept decoupled to mitigate the vibration generated during a cutting operation?? Two approaches were proposed to determine which option (coupled or decoupled bases) provides greater dynamic rigidity. The evidence shows that the decoupled base proposal maintains a cutting operation without displacement peaks due to greater operation times and better damping response.
An improved algorithm for fault detection and location in multi-terminal transmission lines based on wavelet correlation modes
Electric Power Systems Research
https://doi.org/10.1016/j.epsr.2020.106953
H. Alberto Jiménez 1 , Daniel Guillen 2 , Rubén Tapia Olvera 1 , Gerardo Escobar 3 , Francisco Beltran Carbajal 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
3 Instituto Tecnológico de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias
4 Universidad Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: Fault detection, Fault location, Multi-terminal, Transmission lines, Tapped lines, Wavelet correlation modes, Wavelet transform.
Abstract: This paper proposes a new time-domain method for fault detection and location in alternating current multi-terminal transmission lines based on wavelet analysis called wavelet correlation modes. Power system protection of multi-terminal transmission lines is a complex task because the infeed effect may affect its performance. The proposed algorithm based on one-terminal measurements enhances the detection time and diminishes the error of the fault location. This approach suits the protection scheme to attain reliable and accurate performance when any fault type is presented at different locations along the transmission line. The applicability of this proposal is validated under different fault scenarios and compared against conventional protection algorithms. The proposed algorithm is implemented in MATLAB software, and all simulations are conducted in the Alternative Transients Program of the Electromagnetic Transients Program (ATP/EMTP) software. The presented results confirm the main advantages of this approach. The new introduced method is tested under different mother wavelets to estimate the fault location.
Global exponential attitude tracking for spacecraft with gyro bias estimation
ISA Transactions
https://doi.org/10.1016/j.isatra.2021.01.041
Eduardo Espíndola López 1 , Yu Tang Xu 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Attitude tracking, Contraction analysis, Gyro bias observer, Unwinding-free, Spacecraft
Abstract: Relying on contraction analysis, this paper addresses the global attitude tracking problem of a spacecraft when angular velocity measurements are corrupted by bias. A nonlinear observer with exponential convergence is designed firstly to estimate the bias in gyro sensors. Then an exponentially convergent attitude tracking controller with gyro bias correction is devised. Next, to remove the topological constraints of unit quaternions for global stability, a switching variable with hysteresis is incorporated in the control loop, enhancing the robustness in the presence of measurement noise and energy efficiency by preventing the unwinding phenomenon. Numeric simulations are shown to illustrate the performance and compare with other similar controllers in terms of tracking error, estimation error and energy efficiency, as well as the robustness to noisy measurements and time-varying bias in gyro sensors.
Aircraft Engine Gas-Path Monitoring and Diagnostics Framework Based on a Hybrid Fault Recognition Approach
Aerospace
https://doi.org/10.3390/aerospace8080232
Juan Luis Pérez Ruiz 1 , Yu Tang Xu 1 , Igor Loboda 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Aircraft engine, gas turbine, monitoring, diagnostics, ProDiMES, fault recognition
Abstract: Considering the importance of continually improving the algorithms in aircraft engine diagnostic systems, the present paper proposes and benchmarks a gas-path monitoring and diagnostics framework through the Propulsion Diagnostic Methodology Evaluation Strategy (ProDiMES) software developed by NASA. The algorithm uses fleet-average and individual engine baseline models to compute feature vectors that form a fault classification with healthy and faulty engine classes. Using this classification, a hybrid fault-recognition technique based on regularized extreme learning machines and sparse representation classification was trained and validated to perform both fault detection and fault identification as a common process. The performance of the system was analyzed along with the results of other diagnostic frameworks through four stages of comparison based on different conditions, such as operating regimes, testing data, and metrics (detection, classification, and detection latency). The first three stages were devoted to the independent algorithm development and self-evaluation, while the final stage was related to a blind test case evaluated by NASA. The comparative analysis at all stages shows that the proposed algorithm outperforms all other diagnostic solutions published so far. Considering the advantages and the results obtained, the framework is a promising tool for aircraft engine monitoring and diagnostic systems.
Over a Century of Sinking in Mexico City: No Hope for Significant Elevation and Storage Capacity Recovery
Journal of Geophysical Research: Solid Earth
https://doi.org/10.1029/2020JB020648
E. Chaussard 1 , Emre Havazli 2 , H. Fattahi 2 , Enrique Cabral Cano 3 , Darío Solano Rojas 4
1 University of Oregon, Department of Earth Sciences
2 California Institute of Technology, Jet Propulsion Laboratory
3 Universidad Nacional Autónoma de México, Instituto de Geofísica
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: Many areas worldwide are known to experience land subsidence due to groundwater extraction. It is traditionally assumed that subsidence extent and rates are controlled by groundwater extraction locations and volumes. Here, we reevaluate this assumption in the Mexico City metropolitan area by combining stratigraphic, hydrologic, geodetic, and demographic datasets. Integration of 115 years of leveling with 24 years of Interferometric Synthetic Aperture Radar (InSAR) and 14 years of GPS data reveals that subsidence rates have been mostly constant in Mexico City since at least 1950 and reach 50 cm/year. Analysis of InSAR and GPS data shows that no significant elastic deformation exists, demonstrating that the subsidence is almost fully irreversible. In Mexico City, no direct relationships exist between groundwater level fluctuations and subsidence rates or between pumping rates and subsidence rates. In contrast, a strong positive linear relationship is isolated between subsidence rates and the thickness of the upper aquitard. Through the integration of these long-term datasets, we forecast that it will take ?150 years to reach total compaction of the upper aquitard, which may lead to additional subsidence up to 30 m. With the potentiometric surface now deeper than most of the aquitard, clay's porewater rich in salts, chemical constituents, and pollutants is now flowing downward into the productive aquifer, hence decreasing water quality. Finally, our work shows that the consequences of land subsidence greatly influence the socioeconomic landscape in the Mexico City metropolitan area.
Imbibition in conical capillaries under temperature gradients
Physics Letters A
https://doi.org/10.1016/j.physleta.2021.127573
J. Melesio Sánchez Huerta 1 , Arnulfo Ortíz Gómez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Imbibition, Conical capillary, Temperature gradient, Flow and capillary pressure
Abstract: We present a theoretical and experimental study of the dynamics of a fluid through non-rectilinear capillaries. Penetration (imbibition), or rise, in capillaries with a smooth geometry changing under the influence of temperature gradients is a topic that has attracted considerable interest because of the various applications within the inkjet, cosmetics and crude oil extraction industries. The theoretical model we present has been validated with laboratory results; using an experimental acrylic cell in which conical capillary perforations were made. The results show the dependence on temperature effects of both the change in geometry and the change in viscosity and surface tension. The fluid used in the experiments was glycerol, and the images presented here show the penetration and ascent of the liquid within the capillary. The theoretical and experimental results correlate well.
Influence of the viscoelectric effects on the electrokinetic power generation controlled by an osmotic semi-membrane placed on a parallel-plate microchannel
Jorunal of Physics D: Applied Physics
https://doi.org/10.1088/1361-6463/abd710
G. Sánchez 1 , Federico Méndez Lavielle 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: semi-impermeable osmotic membrane, streaming potential, integrodifferential equations, energy conversion, electric power generation
Abstract: In the present work, we develop a theoretical study for predicting the streaming potential and, therefore, the electric power generation in a system composed of a semi-permeable osmotic membrane inserted in a slit microchannel. Both physical systems are communicated through the forced microcirculation of an electrolyte employing the use of a saline gradient, which is established between the external faces of the membrane, creating the suction force needed to induce a hydrodynamic flow. In this manner, we externally impose a uniform volumetric flow rate to promote simultaneous hydrodynamic and electrokinetic fields, replacing the usual external pressure gradient with an equivalent osmotic pressure force. The viscoelectric effects of the electrolyte solution are included in the present analysis. The resulting non-linear governing equations for the motion are written in dimensionless form and permit us to derive an integro-differential equation for the velocity field, which is solved by an iterative method. With the aid of these previous results, the electric energy, in terms of an electrokinetic streaming potential and the streaming current, is generated for this combined system. This proposed electric power generation technique converts the energy of a saline gradient into electrical energy, avoiding the mechanical use of an external pressure gradient.
Experimental Permeability Tensor for Fractured Carbonate Rock
Rock Mechanics and Rock Engineering
https://doi.org/10.1007/s00603-020-02323-9
D. Cabrera 1 , Fernando Samaniego Verduzco 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fractured rock, permeability tensor, confining pressure, experimental
Abstract: This paper presents a novel petrophysical experiment for measuring the 3D permeability tensor at reservoir conditions in fractured vuggy carbonate rock. The permeability variation with confining pressure is demonstrated through the experimental investigation; the permeability ellipse plots show the decrease of permeability, as a function of the increase in effective stress. The experiment was developed at reservoir conditions (120 °C temperature and variable confining pressure) in a native whole rock sample, from the Gulf of Mexico naturally fractured and vuggy reservoir. The analysis of the laboratory data reveals the elliptical behavior of permeability. Two ellipses were generated, one corresponding to the fracture network (secondary porosity system) and another for matrix porosity and permeability (primary porosity system). An important result is the compaction of the representative fracture network ellipse until it fuses with the matrix porosity ellipse at a high confining pressure state. The test contributes to the understanding of the mechanical and flow aspects of permeability, for naturally fractured reservoirs. The experimental results provide a basis for improving reservoir simulation studies, to obtain realistic predictions of reservoir behavior.
Estimation of Hydraulic Gradient for a Transport Pipeline
Journal of Pressure Vessel Technology
https://doi.org/10.1115/1.4048322
Jorge Luis Rojas Arce 1 , María Cristina Verde Rodarte 2 , Flor Lizeth Torres Ortiz 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Pipeline computational model, hydraulic gradient estimation, extended Kalman filter, continuous pipeline monitoring
Abstract: This work deals with the hydraulic gradient estimation in real-time of a transport pipeline computational model by considering a slightly compressible fluid and slightly deformable conduit walls. Since the hydraulic gradient (J(Q)) caused by the friction phenomenon in a pipeline plays an important role in the system's behavior, and this function is affected by fluid properties' deviations, environmental disturbances and conduit deteriorations, it is proposed that the on-line estimation of J(Q) could be part of a monitoring system. The proposition can be applied to obtain computational models of a line with a junction and assumes only measurements of pressure and flow rate at the ends of the conduit and the junction outflow. The generic form of the gradient function J(Q) is a second-order polynomial with coefficients that involve indirectly pipe roughness, the transversal area of the conduit, fluid viscosity and elements connected to the line. The extended Kalman filter (EKF) is applied to estimate the coefficients of the function J(Q). As a test apparatus, a 163??m long hydraulic pipeline is used. Diverse experiments show the usefulness of the on-line estimation of J(Q) for monitoring and simulation tasks where computational models are necessary.
Experiments of an IoT-based wireless sensor network for flood monitoring in Colima, Mexico
Journal of Hydroinformatics
https://doi.org/10.2166/hydro.2021.126
Oliver Mendoza Cano 1 , Raúl Aquino Santos 2 , Jesús López De la Cruz 1 , Robert Edwards 3 , A. Khouakhi 4 , I. Pattison 5 , Víctor Rangel Licea 6 , Esli Castellanos Berjan 2 , M. A. Martínez Preciado 1 , P. Rincón Avalos 1 , P. Lepper 7 , Amado Gutiérrez Gómez 6 , J. M. Uribe Ramos 1 , J. Ibarreche 8 , I. Pérez 8
1 Universidad de Colima, Facultad de Ingeniería Civil
2 Universidad de Colima, Facultad de Telemática
3 Loughborough University, 5G Research Centre
4 Cranfield University, Centre for Environmental and Agricultural
5 Heriot-Watt University, Institute of Infraestructure and Environment
6 Universidad Nacional Autónoma de México, Facultad de Ingeniería
7 Loughborough University, School of Mechanical, Electrical and Manufacturing Engineering
8 Tairda, S. A. de C. V.

Keywords: Digital water network, early warning systems, flooding, tropical storms
Abstract: Urban flooding is one of the major issues in many parts of the world, and its management is often challenging. One of the challenges highlighted by the hydrology and related communities is the need for more open data and monitoring of floods in space and time. In this paper, we present the development phases and experiments of an Internet of Things (IoT)-based wireless sensor network for hydrometeorological data collection and flood monitoring for the urban area of Colima-Villa de Álvarez in Mexico. The network is designed to collect fluvial water level, soil moisture and weather parameters that are transferred to the server and to a web application in real-time using IoT Message Queuing Telemetry Transport protocol over 3G and Wi-Fi networks. The network is tested during three different events of tropical storms that occurred over the area of Colima during the 2019 tropical cyclones season. The results show the ability of the smart water network to collect real-time hydrometeorological information during extreme events associated with tropical storms. The technology used for data transmission and acquisition made it possible to collect information at critical times for the city. Additionally, the data collected provided essential information for implementing and calibrating hydrological models and hydraulic models to generate flood inundation maps and identify critical infrastructure.
Application of comparative design study in the development of preservation encasements for historical documents
Archive of Mechanical Engineering
https://doi.org/10.24425/ame.2021.138394
Alejandro Cuauhtémoc Ramírez Reivich 1 , María del Pilar Corona Lira 1 , Diego A. Zamora García 1 , Anahí Velazquez Silva 1 , Vicente Borja Ramírez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Comparative design study, engineering design, preservation encasements
Abstract: The preservation of historical documents is a task that requires a multidisciplinary team. Mechanical engineering can make valuable contributions. Historical documents made of paper have unique characteristics that must be considered for their preservation and exhibition. Specially designed encasements have emerged as a solution to meet these requirements. In the present research, a comparative design study was carried out. The study comprises identifying the main functions of the encasements. Subsequently, it is analyzed how the capsules that appear in the literature have solved these functions. With the information obtained, three new encasements were designed for historical documents in Mexico. From the results and design experiences, some insights and design principles were obtained; these can be universally applied.
Review on Ammonia as a Potential Fuel: From Synthesis to Economics
Energy Fuels
https://doi.org/10.1021/acs.energyfuels.0c03685
Agustín Valera Medina 1 , F. Amer Hatem 2 , A. K. Azad 3 , I. C. Dedoussi 4 , M. De Joannon 5 , R. X. Fernandes 6 , P. Glarborg 7 , H. Hashemi 7 , X. He 6 , S. Mashruk 1 , J. McGowan 8 , C. Mounaim Rouselle 9 , Armando Ortiz Prado 10 , A. Ortiz Valera 10 , I. Rossetti 11 , B. Shu 6 , M. Yehia 12 , H. Xiao 13 , M. Costa 14
1 Cardiff University, College of Physical Sciences and Engineering
2 Ministry of Education
3 Universiti Brunei Darussalam, Faculty of Integrated Technologies
4 Delft University of Technology, Faculty of Aerospace Engineering
5 Istituto di Scienze e Tecnologie per l'Energia e la Mobilita Sostenibili, Consiglio Nazionale delle Ricerche
6 Physikalisch-Technische Bundesanstalt, Department of Physical Chemistry
7 Technical University of Denmark, Chemical Engineering
8 University of Massachusetts, Mechanical and Industrial Engineering
9 University of Orleans, PRISME
10 Universidad Nacional Autónoma de México, Facultad de Ingeniería
11 Università degli Studi di Milano, Department of Chemistry
12 Cairo University, Faculty of Engineering
13 Guangzhou Maritime University, School of Naval Architecture and Ocean Engineering
14 Universidade de Lisboa, Instituto Superior Técnico

Keywords:
Abstract: Ammonia, a molecule that is gaining more interest as a fueling vector, has been considered as a candidate to power transport, produce energy, and support heating applications for decades. However, the particular characteristics of the molecule always made it a chemical with low, if any, benefit once compared to conventional fossil fuels. Still, the current need to decarbonize our economy makes the search of new methods crucial to use chemicals, such as ammonia, that can be produced and employed without incurring in the emission of carbon oxides. Therefore, current efforts in this field are leading scientists, industries, and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis, this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector, moving through all of the steps in the production, distribution, utilization, safety, legal considerations, and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed, thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works, this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further, the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes, legal barriers that will be faced to achieve its deployment, safety and environmental considerations that impose a critical aspect for acceptance and wellbeing, and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein, this work sets the principles, research, practicalities, and future views of a transition toward a future where ammonia will be a major energy player.
Photolithographically-patterned C-MEMS graphene by carbon diffusion through nickel
Nanotechnology
https://doi.org/10.1088/1361-6528/abedee
Sveidy Vaca 1 , Oscar Pilloni 2 , Axel Rodríguez Gómez 3 , Laura N. Serkovic Loli 4 , Naser Qureshi 5 , Laura Oropeza Ramos 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Física
4 Centro Atómico Bariloche, División Superficies
5 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: C-MEMS, graphene, SU-8, microstructure, pyrolysis, annealing
Abstract: In recent years the most studied carbon allotrope has been graphene, due to the outstanding properties that this two-dimensional material exhibits; however, it turns out to be a difficult material to produce, pattern, and transfer to a device substrate without contamination. Carbon microelectromechanical systems are a versatile technology used to create nano/micro carbon devices by pyrolyzing a patterned photoresist, making them highly attractive for industrial applications. Furthermore, recent works have reported that pyrolytic carbon material can be graphitized by the diffusion of carbon atoms through a transition metal layer. In this work we take advantage of the latter two methods in order to produce multilayer graphene by improving the molecular ordering of photolithographically-defined pyrolytic carbon microstructures, through the diffusion (annealing) of carbon atoms through nickel, and also to eliminate any further transfer process to a device substrate. The allotropic nature of the final carbon microstructures was inspected by Raman spectroscopy (Average ID/IG of 0.2348 ± 0.0314) and TEM clearly shows well-aligned lattice planes of 3.34 ? fringe separation. These results were compared to measurements made on pyrolytic carbon (Average ID/IG of 0.9848 ± 0.0235) to confirm that our method is capable of producing a patterned multilayer graphene material directly on a silicon substrate.
On the Detection and Long-Term Path Visualisation of A-68 Iceberg
Remote sensing
https://doi.org/10.3390/rs13030460
Ludwin López López 1 , Flavio Parmiggiani 2 , Miguel Moctezuma Flores 1 , Lorenzo Guerrieri 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Institute of Atmospheric Sciences and Climate, Bologna

Keywords: SAR image processing, A-68 iceberg, stochastic processes
Abstract: The article presents a methodology for examining a temporal sequence of synthetic aperture radar (SAR) images, as applied to the detection of the A-68 iceberg and its drifting trajectory. Using an improved image processing scheme, the analysis covers a period of eighteen months and makes use of a set of Sentinel-1 images. A-68 iceberg calved from the Larsen C ice shelf in July 2017 and is one of the largest icebergs observed by remote sensing on record. After the calving, there was only a modest decrease in the area (about 1%) in the first six months. It has been drifting along the east coast of the Antarctic Peninsula, and is expected to continue its path for more than a decade. It is important to track the huge A-68 iceberg to retrieve information on the physics of iceberg dynamics and for maritime security reasons. Two relevant problems are addressed by the image processing scheme presented here: (a) How to achieve quasi-automatic analysis using a fuzzy logic approach to image contrast enhancement, and (b) The use of ferromagnetic concepts to define a stochastic segmentation. The Ising equation is used to model the energy function of the process, and the segmentation is the result of a stochastic minimization.
Reconstructing the tectono-sedimentary evolution of the Early??Middle Jurassic Tlaxiaco Basin in southern Mexico: New insights into the crustal attenuation history of southern North America during Pangea breakup
Geosphere
https://doi.org/10.1130/GES02309.1
Mildred Zepeda Martínez 1 , Michelangelo Martini 2 , Luigi Solari 3 , Claudia Cristina Mendoza Rosales 4
1 Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Tierra
2 Universidad Nacional Autónoma de México, Instituto de Geología
3 Universidad Nacional Autónoma de México, Centro de Geociencias
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: During Pangea breakup, several Jurassic extensional to transtensional basins were developed all around the world. The boundaries of these basins are major structures that accommodated continental extension during Juras-sic time. Therefore, reconstructing the geometry of Jurassic basins is a key factor in identifying the major faults that produced continental attenuation during Pangea breakup. We reconstruct the tectono-sedimentary evolution of the Jurassic Tlaxiaco Basin in southern Mexico using sedimentologic, petro-graphic, and U-Pb geochronologic data. We show that the northern boundary of the Tlaxiaco Basin was an area of high relief composed of the Paleozoic Acatlán Complex, which was drained to the south by a set of alluvial fans. The WNW-trending Salado River??Axutla fault is exposed directly to the north of the northernmost fan exposures, and it is interpreted as the Jurassic structure that controlled the tectono-sedimentary evolution of the Tlaxiaco Basin at its northern boundary. The eastern boundary is represented by a topographic high composed of the Proterozoic Oaxacan Complex, which was exhumed along the NNW-trending Caltepec fault and was drained to the west by a major mean-dering river called the Tlaxiaco River. Data presented in this work suggest that continental extension during Pangea breakup was accommodated in Mexico not only by NNW-trending faults associated with the development of the Tam-aulipas??Chiapas transform and the opening of the Gulf of Mexico, but also by WNW-trending structures. Our work offers a new perspective for future studies that aim to reconstruct the breakup evolution of western equatorial Pangea.
Steric and Slippage Effects on Mass Transport by Using an Oscillatory Electroosmotic Flow of Power-Law Fluids
Micromachines
https://doi.org/10.3390/mi12050539
Rubén Baños 1 , José Carlos Arcos Hernández 1 , Oscar Eladio Bautista Godínez 1 , Federico Méndez Lavielle 2
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Steric effect, power-law fluids, boundary slip, oscillatory electroosmotic flow, mass transport rate
Abstract: In this paper, the combined effect of the fluid rheology, finite-sized ions, and slippage toward augmenting a non-reacting solute??s mass transport due to an oscillatory electroosmotic flow (OEOF) is determined. Bikerman??s model is used to include the finite-sized ions (steric effects) in the original Poisson-Boltzmann (PB) equation. The volume fraction of ions quantifies the steric effects in the modified Poisson-Boltzmann (MPB) equation to predict the electrical potential and the ion concentration close to the charged microchannel walls. The hydrodynamics is affected by slippage, in which the slip length was used as an index for wall hydrophobicity. A conventional finite difference scheme was used to solve the momentum and species transport equations in the lubrication limit together with the MPB equation. The results suggest that the combined slippage and steric effects promote the best conditions to enhance the mass transport of species in about 90% compared with no steric effect with proper choices of the Debye length, Navier length, steric factor, Womersley number, and the tidal displacement.
Slippage effect on interfacial destabilization driven by standing surface acoustic waves under hydrophilic conditions
Physical Review Fluids
https://doi.org/10.1103/PhysRevFluids.6.024002
Jaime Ernesto Muñoz 1 , José Carlos Arcos Hernández 2 , I. Campos Silva 1 , Oscar Eladio Bautista Godínez 2 , Federico Méndez Lavielle 3
1 Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: In the present work, we theoretically analyze the influence of the slippage phenomenon on the atomization via surface acoustic waves of a millimeter-order water drop deposited over a hydrophilic substrate. The analysis is conducted by considering, in the first place, a standing surface acoustic wave acting at the free surface of the parent drop. Subsequently, the lubrication theory is applied to the flow field governing equations to derive an evolution equation of the air-liquid interface in terms of the acoustic capillary number and the Navier-slip coefficient. Such an equation's numerical solution leads to a simplified drop model, depicting the spatiotemporal deformation of the free surface under the influence of slippage phenomenon and predicts the atomization threshold once the instability length at the induced capillary waves is achieved. Our numerical simulations show that the high-frequency acoustic excitation under consideration leads to the development of a standing wave at the free surface, which oscillates at a viscous-capillary resonance frequency on order 104 Hz. Moreover, a spreading phenomenon on the fluid drop is induced, strongly linked to the magnitude of the acoustic capillary number. In this scenario, the slippage under hydrophilic conditions has a noticeable impact on the free surface dynamics, causing smaller aerosol characteristic diameters in comparison with the no-slip case. In this context, the present study provides an analytical expression that calculates the droplet diameter in terms of the slip coefficient. In the process, we postulate the slippage phenomenon as a valuable means to control the parent drop's deformation mechanism and, therefore, the aerosol characteristic diameter.
Asymptotic Determination of the Liquefaction Depth for Short and Long Water Waves
Journal of Waterway, Port, Coastal, and Ocean Engineering
https://doi.org/10.1061/(ASCE)WW.1943-5460.0000630
A. Quesada Torres 1 , Eric Gustavo Bautista Godínez 1 , Federico Méndez Lavielle 2
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Long waves, Poroelasticity, Dynamic models, Water waves, Soil pressure, Shear modulus, Soil modulus, Soil liquefaction
Abstract: In this work, an analytical solution that models the dynamic response of a poroelastic soil, induced by the action of water waves in a stratified fluid, is obtained. We propose a reduction of the generalized governing equations for the limit when the horizontal displacements of the porous soil are very small compared with the vertical displacements. The results obtained are similar to those calculated with the governing equations in their complete form. We consider that the instantaneous liquefaction depth is unknown; therefore, the boundary value problem is solved as an eigenvalue problem. The instantaneous liquefaction depth is calculated for a wide range of wave frequencies, from long waves to short waves. It is found that liquefaction depth increases with increasing wavelength. For large values of soil shear modulus, the liquefaction depth increases because the pore pressure magnitude is larger than for the case of soils with low shear modulus. This work can be used as a benchmark to identify the effects that the physical parameters of a poroelastic soil have on the liquefaction depth.
Design parameter analysis for ATSC 1.0 single frequency networks based on receiver multipath handling performance
ETRI Journal
https://doi.org/10.4218/etrij.2020-0231
Mario A. Hernández Flores 1 , Rodrigo Galeano Torres 2 , Miguel A. García Castillo 3 , Salvador Landeros Ayala 1 , José María Matías Maruri 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Federal de Telecomunicaciones
3 Cisco Systems de México

Keywords: Advanced television systems committee, network design parameters, receiver multipath handling performance, single frequency network, terrestrial digital television
Abstract: This work proposes suitable network configurations for single frequency networks (SFNs) with ATSC 1.0 based on network coverage calculations and the laboratory multipath handling performance of commercial receivers. SFNs are widely used for delivering terrestrial digital television services because of their efficient use of the spectrum. In Mexico the analogue television transmissions switch-off occurred on 31 December 2016. Thus it is expected the adopted ATSC 1.0 system will be in force for the next several years despite the recent standardization of the ATSC 3.0 system. As ATSC 1.0 uses 8-VSB modulation the multipath handling capability of receivers is critical for the design of SFNs. The presented network planning results help develop technical normativity for implementing SFNs in Mexico and other countries that use ATSC 1.0. SFNs with transmitter separation up to 130 km are fully covered for outdoor reception mainly due to the directivity of the receiving antenna. Moreover for indoor reception at least 70% of an SFN coverage area can be achieved with a transmitter separation of up to 60 km depending on the radiated power and the transmitter antenna height.
Vertical-axis wind-turbine computations using a 2D hybrid wake actuator-cylinder model
Wind Energy Science
https://doi.org/10.5194/wes-6-1061-2021
Edgar Martínez Ojeda 1 , Francisco Javier Solorio Ordaz 1 , Mihir Sen 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 University of Notre Dame, Department of Aerospace and Mechanical Engineering

Keywords:
Abstract: The actuator-cylinder model was implemented in OpenFOAM by virtue of source terms in the Navier??Stokes equations. Since the stand-alone actuator cylinder is not able to properly model the wake of a vertical-axis wind turbine, the steady incompressible flow solver simpleFoam provided by OpenFOAM was used to resolve the entire flow and wakes of the turbines. The source terms are only applied inside a certain region of the computational domain, namely a finite-thickness cylinder which represents the flight path of the blades. One of the major advantages of this approach is its implicitness ?? that is, the velocities inside the hollow cylinder region feed the stand-alone actuator-cylinder model (AC); this in turn computes the volumetric forces and passes them to the OpenFOAM solver in order to be applied inside the hollow cylinder region. The process is repeated in each iteration of the solver until convergence is achieved. The model was compared against experimental works; wake deficits and power coefficients are used in order to assess the validity of the model. Overall, there is a good agreement of the pattern of the power coefficients according to the positions of the turbines in the array. The actual accuracy of the power coefficient depends strongly on the solidity of the turbine (actuator cylinder related) and both the inlet boundary turbulence intensity and turbulence length scale (RANS simulation related).
A Novel 3-Way Dual-Band Doherty Power Amplifier for Enhanced Concurrent Operation
IEEE Transactions on Microwave Theory and Techniques
https://doi.org/10.1109/TMTT.2021.3091507
Ruwaybih Alsulami 1 , Patrick Roblin 2 , José Ismael Martínez López 3 , Yunsik Hahn 2 , Chenyu Liang 2 , Zoya Popovic 4 , Vanessa Chen 5
1 The Ohio State University
2 The Ohio State University, Department of Electrical and Computer Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universty of Colorado at Boulder, Department of Electrical, Computer and Energy Engineering
5 Carnegie Mellon University, Department of Electrical and Computer Engineering

Keywords: Concurrent average efficiency, Doherty power amplifier (DPA), dual band, intermodulation (IM), 3-Way DB-DPA, 2-D digital predistortion (DPD)
Abstract: This article presents the architecture and design methodology for a new type of dual-band Doherty power amplifier (DB-DPA), referred to as 3-Way DB-DPA, which consists of a main amplifier for each band and an auxiliary amplifier handling both bands. The 3-Way DB-DPA improves the average drain efficiency in concurrent dual-band operation compared to the traditional 2-Way DB-DPA, by avoiding early clipping in the main amplifiers, while benefiting from load??pulling from the auxiliary power amplifier (PA). This improvement is verified in theory and simulation at the current-source reference planes and in measurement with a fabricated 1.5- and 2-GHz dual-band PA. A statistical analysis using 2-D continuous-wave (CW) signals with long-term evolution (LTE) probability distribution functions (PDFs) is performed and demonstrated an improvement in the concurrent average efficiency by 15 percentage points compared to the conventional 2-Way DB-DPA. In nonconcurrent operation, the measured CW drain efficiency in the lower band (1.5 GHz) is 82.8% at peak and 66.6% at 9.6-dB backoff, and the measured CW drain efficiency in the upper band (2.0 GHz) is 70.0% at peak and 48.4% at 9.4-dB backoff. The CW concurrent-balanced drain efficiency reaches 66.2/52.0% in the 3-Way DB-DPA at 3-/6-dB backoff. In single-band operation at 1.5/2.0 GHz, the average power and average drain efficiency after linearization by digital predistortion (DPD) are 35.1/37.4 dBm and 65.0/53.7%, respectively, for an LTE signal with 10-MHz bandwidth and 6.1-dB peak-to-average power ratio (PAPR). In concurrent operation, the 3-Way DB-DPA is driven by two 10-MHz LTE uncorrelated signals at 1.5 GHz with 6.86-dB PAPR and at 2.0 GHz with 6.26-dB PAPR, and the average total power and average concurrent drain efficiency after DPD are 37.5 dBm and 54.24%, respectively.
Earthquake Waste Management, Is It Possible in Developing Countries? Case Study: 2017 Mexico City Seism
Sustainability
https://doi.org/10.3390/su13052431
Flor Hernández Padilla 1 , Marisol Anglés 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones Jurídicas

Keywords: Mexico City earthquake, disaster waste management, disasters and legislation, legal framework of waste
Abstract: After a seism, sanitation is an issue that requires immediate attention at different levels, with the aim of minimizing the latent risks to the public health. The aim of this study is to develop a methodological framework proposal to analyze the possibility of earthquake waste management, considering technical aspects and legal frameworks after an earthquake in a developing country. The implementation case study, the 2017 Mexico City earthquake, has presented data collection of the types of waste and quantities carried out in the field, as well as from government reports and calculations; furthermore, a study was developed to analyze the capacity installed to earthquake waste management, by means of interviews conducted in the field due to the lack of public and congruent institutional information. Finally, an analysis was conducted of the current legal framework and public policy of disaster waste management. In this sense, earthquake rubble totaled 344,211.3 tons and the estimated weight of households items per collapsed dwelling amounted to 424.16 kg. This manuscript deals with the management of earthquake waste in Mexico, based on the data of the 2017 earthquake; the study also explains possible problems and political challenges about the earthquake waste management with the limited conditions of a developing country.
Deciphering origins and pathways of low-enthalpy geothermal waters in the unconventional geothermal system of Juchipila graben (Central Mexico)
Geothermics
https://doi.org/10.1016/j.geothermics.2021.102076
Andrea Billarent Cedillo 1 , Gilles Levresse 2 , Luca Ferrari 2 , Claudio Inguaggiato 3 , Salvatore Inguaggiato 4 , Eliseo Hernández Pérez 1 , Antonio Hernández Espriú 5 , Fernando Corbo Camargo 2 , Jaime Carrera Hernández 2 , Alberto Arias Paz 5
1 Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Tierra
2 Universidad Nacional Autónoma de México, Centro de Geociencias
3 Centro de Investigación Científica y de Educación Superior de Ensenada, Departamento de Geología
4 Istituto Nazionale di Geofisica e Vulcanologia
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Hydrogeochemical processes, Helium isotopes, Water stable isotopes, Unconventional geothermal system, Mexico
Abstract: This work presents hydrochemical results for groundwater and dissolved gas samples collected from a thermal and cold aquifer in the Juchipila Basin, in southern Sierra Madre Occidental, central Mexico. Thermal springs in the Juchipila Basin reach temperatures of 60?°C, these manifestations are not related to recent or active volcanism as are all the known geothermal fields in Mexico. The thermal waters (>32?°C) are Na-HCO3 and Na-SO4 type, with an anomalous concentration of F, B, Li, and As. Their chemistry likely results from water-rock interaction processes. The cold waters (<32?°C) have a Ca-HCO3 composition typical of recent infiltration and shallow flow, but they have an anomalous concentration of NO3. The δ2H and δ18O indicate a common meteoric source for the warm and cold water plotting along an evaporation line. The waters have higher CO2 and He concentrations than the air-saturated water. The helium composition is mainly atmospheric and terrigenous with a mantle helium contribution of up to 14%. This suggests that faults affecting the region are deeply rooted, permitting mantle helium uprise. Geothermometry gives mean reservoir temperatures of 58??102?°C. Based on these results, we propose a model of hydrothermal circulation in the Juchipila Basin, in which rainwater infiltrates deeply through the graben edges fault system, dissolves ions and crustal helium, incorporates mantle helium, while heated by the geothermal gradient, and eventually surges and mixes with the cold, shallow aquifer along faults cutting the whole succession within the graben.
Development of a refinement algorithm for tetrahedral finite elements
Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería
https://doi.org/10.23967/j.rimni.2020.11.001
Armando Hermosillo Arteaga 1 , Miguel Pedro Romo Organista 2 , Roberto Magaña Del Toro 2 , Jorge Carrera Bolaños 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Finite element analysis, remeshing algorithm, adaptive method, civil engineering, geotechnics, numerical analysis
Abstract: Many of the engineering problems are analyzed using numerical methods such as the finite element (FEM) whose results provide a basis to make basic decisions regarding the design of many important works. It is commonly accepted that FEM computations are reliable; however, the results may be affected by the configuration of the finite element mesh to simulate the medium to be analyzed, this is particularly true when the internal and external boundaries are time dependent, as is the case of soil consolidation. Accordingly, a thorough investigation was carried out with the main purpose of eliminating this shortcoming. The main steps to carried out the development of the innovative geometric procedure to automatically refine finite element tetrahedra-type (3D) are described. This geometric algorithm is based on the theory of fractals and is a generalization of the algorithm for triangular element finite element meshes (2D) [1,2]. This paper presents the fundaments of this new algorithm and shows its great approximation using 3D close form solutions, and its versatility to adapt the original Finite Element Mesh when the load boundary conditions are modified (Neumann conditions).
SBR: A Novel Architecture of Software Defined Network Using the RPL Protocol for Internet of Things
IEEE Access
https://doi.org/10.1109/ACCESS.2021.3106950
Paul Sanmartin 1 , Karen Ávila 2 , Sebástian Valle 2 , Javier Gómez 3 , Daladier Jabba Molinares 2
1 Universidad Simón Bolívar
2 Universidad del Norte
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: QoS, routing protocol, IoT, SDN, RPL, WSN
Abstract: This paper proposes a novel architecture named SBR, a software defined network (SDN) architecture using as a routing protocol RPL, a Protocol for Low-Power, and Lossy Networks for Internet of Things (IoT). The architecture includes the function SIGMA, an objective function used in IoT applications to take routing decisions. This research represents an effort to relate IoT and SDN. This association was developed using RPL-SIGMA to solve various IoT and Wireless Sensor Networks (WSN) problems. At the end, a comparison between SBR (SDN-RPL with SIGMA) and SDN-RPL (without SIGMA) was included. The simulations show that SBR has a better performance concerning packet loss, latency, and energy consumption over an architecture based on IoT without SIGMA. The simulation also demonstrates that SDN can be used to manage the IoT network efficiently.
Never Query Alone: A distributed strategy to protect Internet users from DNS fingerprinting attacks
Computer Networks
https://doi.org/10.1016/j.comnet.2021.108445
Oscar Arana 1 , Héctor Benítez Pérez 1 , Javier Gómez 2 , Miguel López Guerrero 3
1 Universidad Nacional Autónoma de México, Instituto de Investigación en Matemáticas Aplicadas y Sistemas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Departamento de Ingeniería Eléctrica

Keywords: User reidentification, Behavior-based tracking, Privacy, DNS
Abstract: The Domain Name System (DNS) plays an essential role in everyday Internet activities. However, unauthorized access to DNS-generated traffic also poses some serious privacy concerns. For instance, DNS traffic traces can be processed by third parties to identify an Internet user by means of behavioral analysis (i.e., a technique that employs machine learning classifiers to link multiple pieces of traffic belonging to the same person). In general, the more sessions an attacker can link, the more he or she will learn about the interests of an individual, and the more likely that the identity of this user will be revealed. The development of such methods of user identification has been the focus of several pieces of research, and currently, there are several strategies to obtain behavioral fingerprints from DNS traces. However, only a few works have proposed countermeasures to protect users against this privacy threat on the Internet. Furthermore, new technologies such as DNS-over-TLS, DNS-over-HTTPS, or DNS over QUIC can potentially render available countermeasures ineffective. This paper proposes Never Query Alone (NQA), a strategy that allows a set of nodes to modify their DNS query patterns to mitigate the risk of being tracked by DNS resolvers. In NQA, users forward their DNS queries through their neighbors in such a way that the identification accuracy achieved by the attackers is proportionally reduced as the number of participant nodes is increased. A second strategy, called NQA-SA, is also proposed. NQA-SA decreases the accuracy of the attackers to nearly 1 %, independently of the number of participant nodes. Both proposed countermeasures reduce the accuracy of the classifiers at the cost of increasing the delay of the DNS query resolution process. Thus, a trade-off between privacy and delay arises, which is theoretically studied in this work by means of queueing analysis. Experimental results with real networks demonstrate that the proposed countermeasures can significantly degrade the accuracy of commonly used machine learning classifiers, thus increasing the privacy protection of individuals on the Internet.
Multivariable binary adaptive control using higher-order sliding modes applied to inertially stabilized platforms
European Journal of Control
https://doi.org/10.1016/j.ejcon.2021.08.003
Andrei Battistel 1 , Tiago Roux Oliveira 1 , Víctor Hugo Pereira Rodrigues 1 , Leonid Fridman Golredich 2
1 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Binary model reference adaptive control, Higher-order sliding modes exact differentiators, Multiple-input and multiple-Output systems, Global stability-tracking, Inertially stabilized platforms
Abstract: This paper presents an extension of the Binary Model Reference Adaptive Control (BMRAC) for uncertain multivariable (square) systems with non-uniform arbitrary relative degrees using only output feedback and its application to inertially stabilized platforms using a two degree of freedom gimbal as actuator. The BMRAC is a robust adaptive strategy with good transient performance, thus useful for uncertain systems, and the multivariable framework is suitable to deal with mechanical unbalances. Using a newly proposed differentiator with dynamic gains based on higher-order sliding mode, the proposed controller achieves global and exact tracking. To illustrate the effective of the proposed solution, simulations are presented using real-word data obtained from an instrumented vehicle in an irregular ground.
Lyapunov redesign for a class of uncertain systems with delays
Nonlinear Analysis: Hybrid Systems
https://doi.org/10.1016/j.nahs.2021.101096
Marco Antonio Gómez 1 , Christopher D. Cruz Ancona 2 , Leonid Fridman Golredich 2
1 Universidad de Guanajuato, Departamento de Ingeniería Mecánica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Time-delay systems, Lyapunov redesign, Sliding Mode Control
Abstract: We address the robust stabilization problem of a general class of uncertain linear systems with multiple delays from a Lyapunov redesign (LR) methodology that relies on Sliding Mode Control (SMC) theory. The proposed approach, which is based on a well-known (yet not used for LR) class of Lyapunov??Krasovskii functionals, allows us to enlarge the type of uncertain systems with delays that can be stabilized. The uncertainties of the system are compensated within a delay-free sliding manifold that is taken from the time-derivative of the considered functional.
Design of a proportional integral derivative-like continuous sliding mode controller
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5412
Ulises Pérez Ventura 1 , Jesús Mendoza Avila 1 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Frequency domain analysis, Lyapunov functions, robust control applications, sliding mode control
Abstract: A describing function-based design for the continuous sliding mode controller in the proportional integral derivative (PID) form (PID-CSMC) is provided. Two sets of the PID-CSMC gains are suggested. The Harmonic Balance is used to predict the amplitude and frequency of the main harmonic of chattering caused by the presence of fast-parasitic dynamics in the closed-loop. Predicted values of amplitude and frequency allow to compute the average power needed to maintain the trajectories of the system into real sliding modes. The methodology for selection of suboptimal PID-CSMC gains consists of amplitude of chattering and average power minimization, taking into account the presence of a critically damped actuator parameterizing the effects of parasitic dynamics. A novel homogeneous Lyapunov function proves that suggested sets of the PID-CSMC gains ensure, in theory, finite-time stability of the perturbed double integrator without parasitic dynamics, and exact compensation of Lipschitz perturbations. On the other hand, the Loeb's criterion allows to ensure that the PID-CSMC with suggested gains generates orbitally asymptotically stable fast-oscillations in the presence of fast-actuators.
Barrier function-based adaptive higher order sliding mode controllers
Automatica
https://doi.org/10.1016/j.automatica.2020.109355
Salah Laghrouche 1 , Mohamed Harmouche 2 , Yacine Chitour 3 , Hussein Obeid 1 , Leonid Fridman Golredich 4
1 Universite Bourgogne Franche-Comté/UTBM,
2 Actility
3 University Paris Saclay, L2S
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Adaptive sliding modes, Barrier function, Higher order sliding modes
Abstract: In this paper, we present barrier function-based adaptive controllers for fast stabilization of a perturbed chain of integrators with bounded uncertainties. We refer to such controllers as adaptive higher order sliding mode controllers since they are designed for a perturbed chain of integrators of length with bounded uncertainties such that the uncertainty bounds are unknown. We propose an adaptive control feedback law insuring the following: We provide a barrier function based adaptive controller ensuring the finite-time convergence of solutions to a desired vicinity of origin. Moreover, the homogeneity norm of solutions asymptotically tends to zero. The effectiveness of these controllers is illustrated through simulations.
Optimization and heat transfer correlations development of zigzag channel printed circuit heat exchangers with helium fluids at high temperature
International Journal of Thermal Sciences
https://doi.org/10.1016/j.ijthermalsci.2020.106645
Raciel De la Torre 1 , Juan Luis François Lacouture 1 , Cheng Xian Lin 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Florida International University, Department of Mechanical and Materials Engineering

Keywords: Printed compact heat exchanger, IHX, Heat transfer correlation, Friction factors, Optimization, High temperature
Abstract: The printed circuit heat exchanger (PCHE) is an important candidate to be used as intermediate heat exchanger (IHX) in a High Temperature Gas-cooled Reactor (HTGR) plant due to its advantages in terms of safety, heat transfer and compactness. In this work, an analysis of the thermal-hydraulic performance of the zigzag channel PCHE within wide parameter ranges was conducted using computational fluid dynamics (CFD) techniques. The Nusselt number and the Fanning friction factor obtained from simulation were validated using experimental data available. To consider the interaction among parameters with a reduced computing time, the Taguchi method was used, which reduces the quantity of analyzed geometric designs. Optimized designs were proposed to reach the highest Nusselt number and lowest friction losses using the signal to noise ratio as objective function. It was found that the zigzag angle has contribution ratios around 50% and 70% on the values of pressure drop and heat transfer, respectively. Although the zigzag phase-shift was the parameter of least influence, its contribution ratio was close to 10% in the turbulent regime, which is comparable to the zigzag pitch length and bend radius contributions. As the most important contribution, Nusselt number and Fanning friction factor correlations were proposed as functions of the Reynolds number and the geometrical parameters. The new correlations were found to be more accurate as compared to existing ones in the literature.
Geochemical Characterization and Saturation Index (Si) in the Montebello Lagunar System Liquidamber Lagoon, Chiapas Mexico
Nature Environment and Pollution Technology
https://doi.org/10.46488/NEPT.2021.v20i04.004
J. R. Reyes Santiago 1 , Luis Antonio García Villanueva 1 , Georgina Fernández Villagómez 1 , P. Guzmán Guadarrama 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Agricultural waste, Erosion risk, Loss of fertile soil, Water quality
Abstract: The ??Lagunas de Montebello? National Park located in Chiapas, Mexico, is well known for its crystal blue water bodies, some of which, in 2003, started to change color from crystalline to cloudy brown, and occasionally emit a foul smell, contains white-yellowish supernatant debris and dead fish. To determine the causes of the changes in the water characteristics of the ??Liquidambar? lagoon of the Montebello lagoon system, a physicochemical characterization was carried out over the first six meters of the water column, together with geochemical speciation analysis and the saturation index calculation for different minerals. Water was classified as calcium-sulfated and the main mechanism that controlled its chemistry was rocks dissolution. Sulfide was found at all sampled depths in the range of 0.11 to 1.13 mg.L-1. The concentration of sulfate in the water column ranged from 249.21 to 298.7 mg.L-1, carbonate ranged from 140.5 to 261.4 mg.L-1, calcium and magnesium ranged from 94.5 to 146.9 mg.L-1 and 34.2 to 38.3 mg.L-1, respectively. Likewise, oxygen was also found to be oversaturated on the surface with a value of 9.32 mg.L-1. The speciation results and SI indicated that the mineral phases calcite, aragonite, and dolomite were oversaturated, being greater on the surface. The results suggested the possibility that the turbidity, the coloration change, and the whitish supernatant were due to the precipitation of carbonate minerals, microbiologically influenced by the photosynthetic activity in the upper layer of the lagoon water.
Dynamics of a helical swimmer crossing viscosity gradients
Physical Review Fluids
https://doi.org/10.1103/PhysRevFluids.6.083102
Christian Esparza López 1 , Jorge González Gutiérrez 2 , Francisco Javier Solorio Ordaz 2 , Eric Lauga 1 , Roberto Zenit 3
1 University of Cambridge, Department of Applied Mathematics and Theoretical Physics
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Brown University, School of Engineering

Keywords: Cell locomotion, Locomotion, Swimming
Abstract: We experimentally and theoretically study the dynamics of a low-Reynolds number helical swimmer moving across viscosity gradients. Experimentally, a double-layer viscosity is generated by superposing two miscible fluids with similar densities but different dynamic viscosities. A synthetic helical magnetically driven swimmer is then made to move across the viscosity gradients along four different configurations: either head-first (pusher swimmer) or tail-first (puller), and through either positive (i.e., going from low to high viscosity) or negative viscosity gradients. We observe qualitative differences in the penetration dynamics for each case. We find that the swimming speed can either increase or decrease while swimming across the viscosity interface, which results from the fact that the head and the tail of the swimmer can be in environments in which the local viscosity leads to different relative amounts of drag and thrust. In order to rationalize the experimental measurements, we next develop a theoretical hydrodynamic model. We assume that the classical resistive-force theory of slender filaments is locally valid along the helical propeller and use it to calculate the swimming speed as a function of the position of the swimmer relative to the fluid-fluid interface. The predictions of the model agree well with experiments for the case of positive viscosity gradients. When crossing across a negative gradient, gravitational forces in the experiment become important, and we modify the model to include buoyancy, which agrees with experiments. In general our results show that it is harder for a pusher swimmer to cross from low to high viscosity, whereas for a puller swimmer it is the opposite. Our model is also extended to the case of a swimmer crossing a continuous viscosity gradient.
Ambient noise tomography of the Popocatépetl volcano using the principal Green tensor components
Journal of Seismology
https://doi.org/10.1007/s10950-021-10021-4
Martín Cárdenas Soto 1 , Thalía Alfonsina Reyes Pimentel 1 , Josué Tago Pacheco 1 , Thulassiraman Natarajan 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Indian Institute of Science, Centre for Earth Sciences

Keywords: Empirical Green??s function, Seismic interferometry, Surface wave tomography, Dispersion curve, Volcano-tectonic event, Ancient crater, Fast marching method
Abstract: A 3D shear wave velocity model of the subsurface of Popocatépetl volcano was obtained using ambient noise tomography, employing the principal cross-terms of the empirical Green??s function. Daily cross-correlation waveforms were computed from the data recorded by four seismic broadband stations in 2012. Dispersion curves were estimated from the stack of anti-causal and causal parts for the three ground motion components. In the period ranging between 0.5 and 7 s, the radial component provided the most well-defined group velocity dispersion curves for Rayleigh waves. Dispersion curves for long paths (> 9.5 km) suggested the presence of a layered structure with group velocity values ranging from 0.5 to 3.0 km/s. Dispersion curves for short paths (< 7 km) and close to the volcano showed values similar to those for long paths but with a velocity inversion occurring between 3- and 5-s periods. Despite the scarce ray-path coverage, a tomography inversion provided the means to image an S-wave velocity anomaly (2.5??3.0 km/s) in the northern part of the crater at depths not larger than 6 km. The volcano-tectonic seismicity during 2012??2013 was found to be concentrated in the southern segment of this anomaly, which seems to mark a boundary between a solidified body (possibly a product of ancient volcanic craters) and the softer material.
The Search of Diffusive Properties in Ambient Seismic Noise
Bulletin of the Seismological Society of America
https://doi.org/10.1785/0120200189
José Piña Flores 1 , Martín Cárdenas Soto 1 , Antonio García Jerez 2 , Michel Campillo 3 , Francisco José Sánchez Sesma 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Almería, Departamento de Química y Física
3 Universite Grenoble Alpes, Institut des Sciences de la Terre
4 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords:
Abstract: Ambient seismic noise (ASN) is becoming of interest for geophysical exploration and engineering seismology, because it is possible to exploit its potential for imaging. Theory asserts that the Green??s function can be retrieved from correlations within a diffuse field. Surface waves are the most conspicuous part of Green??s function in layered media. Thus, the velocities of surface waves can be obtained from ASN if the wavefield is diffuse. There is widespread interest in the conditions of emergence and properties of diffuse fields. In the applications, useful approximations of the Green??s function can be obtained from cross correlations of recorded motions of ASN. An elastic field is diffuse if the background illumination is azimuthally uniform and equipartitioned. It happens with the coda waves in earthquakes and has been verified in carefully planned experiments. For one of these data sets, the 1999 Chilpancingo (Mexico) experiment, there are some records of earthquake pre?events that undoubtedly are composed of ASN, so that the processing for coda can be tested on them. We decompose the ASN energies and study their equilibration. The scheme is inspired by the original experiment and uses the ASN recorded in an L?shaped array that allows the computation of spatial derivatives. It requires care in establishing the appropriate ranges for measuring parameters. In this search for robust indicators of diffusivity, we are led to establish that under certain circumstances, the S and P energy equilibration is a process that anticipates the diffusion regime (not necessarily isotropy), which justifies the use of horizontal?to?vertical spectral ratio in the context of diffuse?field theory.
A Development PMU Device for Living Lab Applications
Journal of Control, Automation and Electrical Systems
https://doi.org/10.1007/s40313-021-00734-9
Maique C. García 1 , Daniel Dotta 2 , Leandro Pereira 3 , Madson C. De Almeida 1 , Mario Roberto Arrieta Paternina 4 , Orlem Lima Dos Santos 1 , Liz Da Silva 1 , José Eduardo da R. Alves 5
1 University of Campinas
2 University of Campinas, Department of Electrical Engineering
3 Time Energy
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería
5 Centro de Pesquisas de Energia Elétrica

Keywords: Phasor data processing, Hardware, Living lab, PMU, Synchrophasors
Abstract: This paper is focused on the hardware and software development of a compact phasor measurement unit (PMU) device. This project seeks to provide a flexible, compact and development environment of hardware and software platform for advanced monitoring of a living lab Campus network. The development PMU (Dev??PMU) allows the exploration of the phenomena involved in the living lab Campus networks and can be very useful for the development of control and protection advanced applications in Low-Voltage (LV) power systems. The Dev??PMU is built on a general hardware platform and is able to process single as well as three-phase voltages. The performance of the proposed device is evaluated using the PMUCal Fluke set up as the benchmark and under real low-voltage distribution networks. Results confirm the accuracy of the proposed device for providing voltage phasors complying with the Standard limits for class P and M.
Data-driven power system linear model identification for selective modal analysis by frequency interpolations
IET Generation, Transmission and Distribution
https://doi.org/10.1049/gtd2.12084
Francisco Zelaya 1 , Joe H. Chow 2 , Mario Roberto Arrieta Paternina 1 , Alejandro Zamora Méndez 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica

Keywords:
Abstract: This paper proposes a new approach to identify a data-based power system linear model by means of frequency interpolations, aiming to obtain a suitable system representation for selective-modal analysis purposes. The key idea behind the identification process is the Loewner-based frequency interpolation carried out by the Loewner matrices. The proposed approach demonstrates that the Loewner-based frequency interpolation is able to fit a linear model that can be used for small-signal analysis studies, since it provides the state-space representation, the frequency response, and modal information (frequency, damping, and mode-shape). Then, a selective modal analysis is accomplished over two test cases (Kundur and New England??New York power grids) by employing the identified linear model provided by the Loewner-based frequency interpolation method. The attained results confirm the outstanding performance of the proposal which is validated against the small-signal analysis and compared with the eigensystem realisation algorithm, overcoming the absolute error of the model identified with the traditional eigensystem realisation algorithm approach by at least 37 times, and properly capturing the modal information in a frequency band of concern.
Taylor??Fourier Filter-Bank Implemented With O-Splines for the Detection and Classification of Faults
IEEE Transactions on Industrial Informatics
https://doi.org/10.1109/TII.2020.3010268
Daniel Guillen 1 , José Antonio De la O Serna 2 , Alejandro Zamora Méndez 3 , Mario Roberto Arrieta Paternina 4 , Fernando Salinas 2
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
2 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Classification, detection, faults, O-splines, Petri net (PN), Taylor??Fourier filter-bank, transmission lines
Abstract: The article proposes a new method based on a Taylor-Fourier filter-bank implemented with O-splines for the detection and classification of faults. This method defines a multiresolution approach employing a specific design of bandpass filters to improve the fault detection, taking into account the transient information superimposed into the fundamental frequency produced by the faults. The proposed Taylor-Fourier filter-bank with O-splines has been validated considering different scenarios of faults in high voltage transmission lines. Then, an easily adapted classification stage that renders instantaneous classifications according to the fault type is carried out through a Petri net. The results confirm that the proposal presents important advantages since it reduces the detection time and exhibits an outstanding classification performance.
Evidencia de relajaciones dieléctricas en BiFeO3 dopada con Ca2+ y su efecto con la temperatura
Tópicos de Investigaión en Ciencias de la Tierra y Materiales
https://dx.doi.org/10.29057/aactm.v8i8.7587
Fernando Pedro García 1 , Arturo Barba Pingarrón 2
1 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords:
Abstract: La ferrita de bismuto es un material multiferroico que presenta múltiples fenómenos de relajaciones dieléctricas que son características a diferentes temperaturas, por ello presenta grandes valores de permitividad relativa, pero las perdidas dieléctricas son grandes debido a la corriente de fuga que inducen las fases secundarias inherentes debido a que la BiFeO3 es un compuesto inter metálico y para inhibirlas es necesario tener un control muy preciso de la estequiometría, y parámetros de síntesis en general. Por lo tanto se ocuparon iones de Ca2+ como dopante para inhibir las fases secundarias, aumentar la permitividad relativa y reducir las perdidas dieléctricas. Así mismo se evaluaron las energías de activación de las relajaciones dieléctricas y su relación con el dopaje y las valencias mixtas que este induce.
On the paraconsistent Logic CG3
Computación y Sistemas
https://doir.ogr/10.13053/CyS-25-2-3363
Miguel Pérez Gaspar 1 , Verónica Borja Macías 2 , Ismael Everardo Bárcenas Patiño 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Tecnológica de la Mixteca

Keywords: Many-valued logic, paraconsistent logic, Kripke-type semantics, Hilbert calculi, CG'3
Abstract: Paraconsistent logical systems are well-known reasoning frameworks aimed to infer new facts or properties under contradictory assumptions. Applications of these systems are well known in wide range of computer science domains. In this article, we study the paraconsistent logic CG?3, which can be viewed as an extension of the logic G?3. CG?3 is also 3-valued, but with two designated values. Main results can be summarized as follows: a Hilbert-type axiomatization, based on Kalmár??s approach; and a new notion of validity, based on also novel Kripke semantics.
Pyrite Flotation Separation and Encapsulation: A Synchronized Remediation System for Tailings Dams
Mine Water and the Environment
https://doi.org/10.1007/s10230-021-00753-7
P. Camero Hermoza 1 , Dandy Calla Choque 2 , J. C. Rojas Montes 3 , C. Villachica León 4 , J. Villachica Llamosas 4
1 Universidad Nacional de San Antonio Abad del Cusco, Departamento Académico de Ingeniería Metalurgica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Tecnológico de Durango
4 Consulcont S.A.C., Centro de Investigación

Keywords: Acid mine drainage, Pyrite encapsulation, Acid potential, Slimes
Abstract: Pyrite flotation separation and encapsulation in tailings dams is proposed as a viable way to chemically stabilize tailings. Characterization of potential acid mine generation in tailings led to an innovative process in which acid-generating pyrite is separated by flotation from the coarse tailings and incorporated into the slime zone. This creates pyrite-free neutral tailings acceptable for placement in the dyke and permanently avoids acid generation.
Electrodialysis applied to the removal of iron ions in an aqueous solution
Revista Mexicana de Ingeniería Química
https://doi.org/10.24275/rmiq/IA2307
M. Arreola Castro 1 , J. C. Rojas Montes 2 , V.J. Martínez Gómez 1 , Dandy Calla Choque 3 , M. J. Rodríguez Rosales 1 , R. Pérez Garibay 4 , R. Valencia Vázquez 1
1 Instituto Tecnológico de Durango, División de Estudios de Posgrado e Investigación
2 Instituto Tecnológico de Durango
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto Politécnico Nacional, Unidad Saltillo

Keywords: Iron, Electrodialysis, Removal, Current density, Diffusion.
Abstract: Iron is one of the main elements present in surface and ground waters due to mineral leaching or mining industry activities. To avoid the formation of acid mine drainage (AMD), it is necessary to treat the water with the presence of iron to reduce the environmental impact and obtain water that can be reused. In this work, electrodialysis is proposed for removing iron from a solution. To do this, it is necessary to know the appropriate conditions of current density, pH, and concentration to carry out the removal of iron in an analogous solution in concentration to those found in mineral processing. The electrodialysis tests were performed in a two-compartment cell. From the data obtained in the chemical analysis, the removal percentages, the amounts of mass removed, and the removal rates were calculated to determine the best operating parameters. Discussion is also made from the thermodynamics that determines the speciation of iron in the anolyte. The maximum percentage of iron removal reached was 97.15%, with the next parameters: current density of 390 A/m2, initial iron concentration (CFe) of 40 mg/L, initial pH value (pHi) of 4, agitation speed (v) of 500 r.p.m. and temperature (T) of 25°C.
Adaptive neuronal induction motor control with an 84-pulse voltage source converter
Asian Journal of Control
https://doi.org/10.1002/asjc.2322
Francisco Beltran Carbajal 1 , Rubén Tapia Olvera 2 , Antonio Valderrabano González 3 , Irvin López García 1
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Panamericana, Facultad de Ingeniería

Keywords:
Abstract: This paper deals with the problem of harmonic distortion in velocity control drives for large horsepower three-phase induction motors. A new solution alternative to considerably reduce harmonic distortion in controlled large-capacity induction motors is introduced. An adaptive neural velocity reference trajectory tracking control scheme based on an 84-pulse voltage source converter for large horsepower three-phase induction motors is proposed. Desired flux modulus control is simultaneously performed. Adaptive controller parameters are adjustable online using B-spline artificial neural networks. Variable load torque of the handled mechanical dynamic system is assumed to be uncertain. Real-time estimations or measurements of dynamic load torque are unnecessary. Bézier curves are used for desired smooth motion planning to take a large induction motor from its starting towards an operating velocity. Moreover, motion planning is exploited for evasion of harmful mechanical oscillations as well as large peak values of voltages and currents. Closed-loop efficient velocity profile tracking is confirmed on a 500-hp induction motor. Comparisons with 6-pulse and 12-pulse conventional voltage source converters are also included to highlight the superior energy efficiency of the proposed 84-pulse ac motor drive. A very low total harmonic distortion of the multiple-pulse reconstructed three-phase control voltage signals is also proved. Analytical and numerical results prove the effectiveness and efficiency of the introduced 84-pulse adaptive neuronal dynamic tracking control strategy.
Experimental Evaluation and Modeling of Air Heating in a Ceramic Foam Volumetric Absorber by Effective Parameters
Energies
https://doi.org/10.3390/en14092506
Carlos Ernesto Arreola Ramos 1 , Omar Álvarez Brito 1 , Juan Daniel Macías 1 , Aldo Javier Guadarrama Mendoza 1 , Manuel A. Ramírez Cabrera 1 , Armando Rojas Morin 2 , Patricio J. Valadés Pelayo 1 , Heidi Isabel Villafán Vidales 1 , Camilo A. Arancibia Bulnes 1
1 Universidad Nacional Autónoma de México, Instituto de Energías Renovables
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: PSZ porous absorber, volumetric heat transfer coefficient, volumetric effect, heat transfer model
Abstract: Reticulate porous ceramic reactors use foam-type absorbers in their operation which must fulfill two essential functions: favoring the volumetric effect and increasing the mass and heat transfer by acting as a support for the reactive materials. Heating these absorbers with highly inhomogeneous concentrate irradiation induces high thermal gradients that affect their thermal performance. Owing to the critical function of these component in the reactor, it is necessary to define a selection criterion for the foam-type absorbers. In this work, we performed an experimental and numerical thermal analysis of three partially stabilized zirconia (PSZ) foam-type absorbers with pore density of 10, 20, and 30 PPI (pores per inch) used as a volumetric absorber. A numerical model and an analytical approximation were developed to reproduce experimental results, and calculate the thermal conductivity, as well as volumetric heat transfer coefficient. The results show that an increase in pore density leads to an increase in the temperature difference between the irradiated face and the rear face of the absorber, this occurs because when pore density increases the concentrated energy no longer penetrates in the deepest space of the absorber and energy is absorbed in areas close to the surface; therefore, temperature gradients are created within the porous medium. The opposite effect occurs when the airflow rate increases; the temperature gradient between the irradiated face and the rear face is reduced. This behavior is more noticeable at low pore densities, but at high pore densities, the effect is less relevant because the internal structure of porous absorbers with high pore density is more complex, which offers obstructions or physical barriers to airflow and thermal barriers to heat transfer. When the steady state is reached, the temperature difference between the two faces of the absorber remains constant if the concentrate irradiation changes slightly, even changing the airflow rate. The results obtained in this work allow us to establish a selection criterion for porous absorbers that operate within solar reactors; this criterion is based on knowledge of the physical properties of the porous absorber, the environment, the working conditions, and the results expected.
Binational reflections on pathways to groundwater security in the Mexico-United States borderlands
Water International
https://doi.org/10.1080/02508060.2021.1999594
Rosario Sánchez Flores 1 , José Agustín Breña Naranjo 2 , Alfonso Rivera 3 , Randall T. Hanson 4 , Antonio Hernández Espriú 5 , Rick J. Hogeboom 6 , Anita Milman 7 , Jude A. Benavides 8 , Adrián Pedrozo Acuña 2 , Julio Cesar Soriano Monzalvo 2 , Sharon B. Megdal 9 , Gabriel Eckstein 10 , Laura Rodríguez 1
1 Texas A&M University, Texas Water Resources Institute
2 Comisión Nacional del Agua, Instituto Mexicano de Tecnología del Agua
3 Institut National de la Recherché Scientifique Inrs-ete Québec, Quebec, QC, Canada
4 One-Water Hydrologic
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería
6 University of Twente, Faculty of Engineering Technology
7 University of Massachusetts, Department of Environmental Conservation
8 University of Texas Rio Grande Valley, School of Earth, Environmental, and Marine Sciences
9 University of Arizona, Water Resources Research Center
10 Texas A&M University, Texas A&M School of Law

Keywords: Mexico, United States, transboundary aquifers, water security
Abstract: Shared groundwater resources between Mexico and the United States are facing unprecedented stressors. We reflect on how to improve water security for groundwater systems in the border region. Our reflection begins with the state of groundwater knowledge, and the challenges groundwater resources face from a physical, societal and institutional perspective. We conclude that the extent of ongoing cooperation frameworks, joint and remaining research efforts, from which alternative strategies can emerge, still need to be developed. The way forward offers a variety of cooperation models as the future offers rather complex, shared and multidisciplinary water challenges to the Mexico??US borderlands.
Constructal design of top metallic contacts on a disc-shaped solar cell
Journal of Applied Research and Technology
https://doi.org/10.22201/icat.24486736e.2021.19.5.1382
Jorge Armando Ojeda 1 , Sarah Ruth Messina 2 , Erick Eduardo Vázquez 3 , Federico Méndez Lavielle 4
1 Universidad de Colima, Facultad de Arquitectura y Diseño
2 Universidad Autónoma de Nayarit, Unidad Académica de Ciencias Básicas e Ingenierías
3 Universidad de Colima, Facultad de Ingeniería Mecánica y Eléctrica
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: tree-shaped, metallic contacts, disc-shaped body, solar cell, constructal design, resistive power losses
Abstract: Trends in crystalline silicon photovoltaic improvements demonstrate that some of the key factors that have contributed to reaching efficiency values up to 23 % are the introduction of the passivated emitter and rear cell structure with local rear contacts in low-cost large-volume fabrication; the reduction of the width of the front metallization fingers, from about 100 microm to less than 30 micro m in large volume production, and the re-emergence of mono-crystalline silicon wafers as a consequence of cost reduction in the Czochralski silicon ingot fabrication process. In the present work, we have developed a theoretical model that defines the geometric arrangement of a branched top metallic contacts network over a solar cell with a disc-shaped body. The solar cell considers two main regions: the solar cell material and an insert of metallic material for the collection of the photogenerated electrical current. The geometric characteristics of the network are defined from the minimization of the resistive power losses applying the constructal design method. As a fundamental result, the optimal lengths, branching angles, and geometrical relationships of the n-branched network are determined. The numerical results show that the dimensionless power losses of the branched arrangement of contacts present minimum values for the allocation of the metallic material and the disc size of the solar cell.
Nuclear fuel rod cladding oxidation and hydrogen production model based on diffusion theory in a multiphase environment of ZrO2, α-Zr(O), and β-Zr at high temperatures (1273 K??1800 K)
International Journal of Hydrogen Energy
https://doi.org/10.1016/j.ijhydene.2021.01.101
Heriberto Sánchez Mora 1 , Marco A. Polo Labarrios 2 , J. Ortiz Villafuerte 3 , Sergio Quezada García 4 , Edmundo Del Valle Gallegos 5
1 Instituto Politécnico Nacional
2 Universidad Autónoma Metropolitana, Unidad Cuajimalpa
3 Instituto Nacional de Investigaciones Nucleares, Departamento de Sistemas Nucleares
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería
5 Instituto Politécnico Nacional, Escuel Superior de Física y Matemáticas

Keywords: Hydrogen production, Zirconium oxidation, Oxygen diffusion in zirconium, Severe accident, Heat transfer phenomena
Abstract: This paper proposes a mathematical model for the oxidation process of zirconium under the theory of oxygen diffusion in Zircaloy. The model considers ZrO2, α-Zr(O), and β-Zr phases at high temperatures (1273 K??1800 K) in an equivalent fuel rod. The model also considers the heat transfer phenomenon, the decay heat after shutdown, the heat released by the oxidation reaction, the loss of coolant water in the core and the heat transported by the steam produced. A computer program was coded in the C++ environment. The accident scenario of a BWR short term station blackout was simulated with this model. The results are compared with the ones obtained using MELCOR and RELAP/SCDAP codes. The comparison yielded an approximate result for total hydrogen production at the end of the simulation, with a difference of ??2.7% compared with RELAP/SCDAP, and a difference of ??1.11% with MELCOR. With the present model it is possible to calculate the growth of ZrO2, α-Zr(O), and β-Zr phases through the cladding.
Short-Term Interaction between Silent and Devastating Earthquakes in Mexico
Nature Communications
https://doi.org/10.1038/s41467-021-22326-6
Víctor M. Cruz Atienza 1 , Josué Tago Pacheco 2 , Carlos Villafuerte 1 , M. Wei 3 , R. Garza Girón 4 , Luis A. Domínguez 5 , Vladimir Kostoglodov 1 , Takuya Nishimura 6 , Sara Franco 1 , Jorge Real Pérez 1 , Mario A. Santoyo Anaya 1 , Yoshihiro Ito 6 , E. Kazachkina 7
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 University of Rhode Island, Graduate School of Oceanography
4 University of California, Department of Earth and Planetary Sciences
5 Universidad Nacional Autónoma de México, Escuela Nacional de Estudios Superiores Morelia
6 Kyoto University, Disaster Prevention Research Institute
7 Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Tierra

Keywords:
Abstract: Either the triggering of large earthquakes on a fault hosting aseismic slip or the triggering of slow slip events (SSE) by passing seismic waves involve seismological questions with important hazard implications. Just a few observations plausibly suggest that such interactions actually happen in nature. In this study we show that three recent devastating earthquakes in Mexico are likely related to SSEs, describing a cascade of events interacting with each other on a regional scale via quasi-static and/or dynamic perturbations across the states of Guerrero and Oaxaca. Such interaction seems to be conditioned by the transient memory of Earth materials subject to the ??traumatic? stress produced by seismic waves of the great 2017 (Mw8.2) Tehuantepec earthquake, which strongly disturbed the SSE cycles over a 650??km long segment of the subduction plate interface. Our results imply that seismic hazard in large populated areas is a short-term evolving function of seismotectonic processes that are often observable.
Spherical data validation of rock doscontinuities orientation from Done-derived 3D point clouds
Revista Mexicana de Ciencias Geológicas
https://doi.org/10.22201/cgeo.20072902e.2021.3.1641
Javier Mancera Alejandrez 1 , Sergio Macías Medrano 1 , Enrique Villareal Rubio 1 , Darío Solano Rojas 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: rock-discontinuities, spherical statistics models, drone, validation statistical, point cloud
Abstract: This work presents a methodology for the statistical validation of discontinuity surfaces obtained from point clouds using digital photogrammetry from drones. Our methodology allows you to review the quality of the data obtained with photogrammetry and decide whether these measurements are representative of the discontinuity surfaces that they analyze. It consists of three steps, the first one being a shape analysis that allows defining which statistical model should be used: Fisher for circularly symmetric clusters or Bingham fits better for axially symmetric clusters. This step also makes the most significant difference to other works since our methodology starts from the premise that not all discontinuity surfaces are flat. Therefore, Fisher parameters do not allow validating data that do not correspond to a plane. In the second step of the methodology, we calculate the consistency parameters that depend on the statistical model defined in step 1. The parameters are similar for both models; both estimate κ which indicates how much the sample is concentrated around the mean orientation and validates the existence of this and which is the value of the generating angle of a cone with a 95 % confidence limit that it contains within the mean orientation. Finally, step 3 is used when there are control measurements to compare the point cloud data and define if both samples characterize the same discontinuity surface in the rock mass. The results obtained on a rock outcrop allowed us to observe that the measurements obtained from the drone faithfully represent the discontinuity surface analyzed when these were compared with the measurements made manually with the compass. Furthermore, the dispersion parameters (?? and ?95) yielded results that make it possible to ensure that 1) there is a preferential direction (mean orientation) and 2) the mean orientation is representative of the entire measured surface.
Chattering analysis for Lipschitz continuous sliding-mode controllers
Internacional Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.5239
Carlos Arturo Martínez Fuentes 1 , Ulises Pérez Ventura 1 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: chattering, frequency domain analysis, sliding-mode
Abstract: In this article, an analysis of chattering in systems driven by Lipschitz continuous sliding-mode controllers (LCSMC) is performed using the describing function approach. Two kinds of LCSMC are considered: the first one is based on a linear sliding variable (LSV) and the second one on a terminal sliding variable (TSV). Predictions of amplitude, frequency, and average power of self-excited oscillations, are used to compare such LCSMC respect to the supertwisting controller (STC) in systems with fast-actuators. Theoretical predictions and simulations allow the following conclusions: (i) LCSMC still may induce fast-oscillations (chattering) of smaller amplitude and average power, than ones caused by the STC in the absence of the measurement noises. (ii) The level of chattering with LSV-LCSMC could be smaller than one produced by TSV-LCSMC. (iii) The zero (sliding) dynamics of the LSV-LCSMC cannot be arbitrarily fast or the closed-loop system may lose even practical stability, unlike the TSV-LCSMC whose trajectories are finally bounded.
A review of agent-based modeling for simulation of agricultural systems
Revista Dyna
https://doi.org/10.15446/dyna.v88n217.89133
Denys Yohana Mora Herrera 1 , Aida Huerta Barrientos 2 , Orlando Zúñiga Escobar 3
1 Universidad del Valle, Grupo de Investigación en Ciencias Ambientales y de la Tierra
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Centro de Ciencias de la Complejidad

Keywords: agricultural complexity, agricultural systems modeling, adaptive complex systems
Abstract: In this manuscript global research trends are analyzed in agent-based modeling (ABM), which is applied to face the inherent complexity of agricultural systems. The search was carried out in Scopus, during the period 2009-2019, and the VOSviewer© software was used as a bibliometric tool. The results show that ABM is used under two approaches: research and policy evaluation, and in three thematic areas: systems and computation sciences, geography and ecology and environmental science. The purpose of this study is to investigate three types of phenomena: land-use changes, water management and agricultural policy evaluation. ABM has been shown to be useful for exploring and understanding the society-nature relationship of agricultural systems under an interdisciplinary and transdisciplinary approach, and for supporting decision-making processes via its application in a Latin American context, which for our purposes is still of utmost importance.
Alternative approach for efficient OPF calculations in hybrid AC/DC power grids with VSC-HVDC systems based on shift factors
International Journal of Electrical Power & Energy Systems
https://doi.org/10.1016/j.ijepes.2020.106395
Néstor González Cabrera 1 , Luis Miguel Castro González 1 , Guillermo Gutiérrez Alcaraz 2 , José Horacio Tovar Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Morelia, Posgrado en Ingeniería Eléctrica

Keywords: AC/DC grids, Multi-terminal VSC-HVDC systems, optimal power flows, piece wise linear functions, shift factors
Abstract: This paper introduces a novel approach for optimal power flows (OPF) in VSC-HVDC power grids based on shift factors. The optimum solution is calculated using a global equality constraint (generation minus losses equals system load) plus those related to the power set points of the VSC units. Indeed, the shift factors enable the enforcement of the VSC power flow constraints. This is the hallmark of this method which features a considerable reduction of the model complexity and the computational burden because the system nodal equations are not explicitly represented. This lies in sharp contrast with existing OPF approaches whose model complexity is inevitably increased as is the computing requirements to its solution. Three variants of the proposed OPF model are described: (i) quadratic generation cost curves with quadratic AC/DC transmission losses; (ii) quadratic generation cost curves with power losses considered by piecewise linear equations; (iii) generation cost curves and transmission losses approximated by piecewise linear functions. The effectiveness of the developed approach is assessed using three AC/DC test systems formed by three, four and six VSC stations, respectively. The results are compared against those calculated by a conventional Sequential Quadratic Programming formulation using a full, nonlinear power grid model. It is demonstrated that the optimal solutions concur very well between each other since errors inferior to 5% are obtained for the generation dispatch and nodal energy prices. Equally important is the fact that this novel approach reduces the computational time by more than 70% on average.