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Artículos publicados en: 2020

Mu-Calculus Satisfiability with Arithmetic Constraints
Programming and Computer Software
Y. Limón 1 , Edgard Benítez Guerrero 1 , Ismael Everardo Bárcenas Patiño 2 , Guillermo Molero Castillo 2 , Alejandro Velázquez Mena 2
1 Universidad Veracruzana
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The propositional modal μ-calculus is a well-known specification language for labeled transition systems. In this work, we study an extension of this logic with converse modalities and Presburger arithmetic constraints, interpreted over tree models. We describe a satisfiability algorithm based on breadth-first construction of Fischer-Lardner models. An implementation together several experiments are also reported. Furthermore, we also describe an application of the algorithm to solve static analysis problems over semi-structured data.
Novel numerical solution to the fractional neutron point kinetic equation in nuclear reactor dynamics
Annals of Nuclear Energy
Marco A. Polo Labarrios 1 , Sergio Quezada García 2 , Gilberto Espinosa Paredes 3 , L. Franco Pérez 1 , J. Ortiz Villafuerte 4
1 Universidad Autónoma Metropolitana, Unidad Cuajimalpa
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
4 Instituto Nacional de Investigaciones Nucleares, Departamento de Sistemas Nucleares

Keywords: Reactor dynamics, Fractional neutron point kinetic equations, Anomalous diffusion coefficient, Sinusoidal reactivity, Multi term higher-order linear approximation
Abstract: In this work, a novel numerical solution to modified Fractional Neutron Point Kinetic (FNPK) equations is presented. The method is based on a numerical solution to linear multi-term fractional differential equations taking from scientific literature. Differential-integral operators of fractional order are numerically solved with the novel method. The impact of the order of the operators has been assessed during the process of order reduction of the fractional differential-integral equation. The numerical solution is applied to case with sinusoidal reactivity, and different values of the anomalous diffusion order are used to study the effect on the neutron density. The results of the neutron density behavior obtained with this proposed numerical novel solution were compared against the classical neutron point kinetics equations and with other results from scientific literature. The comparison showed a clear improvement of the numerical results when using a fractional differential-integral operator instead of an only fractional differential operator.
Presburger constraints in trees
Computación y Sistemas
Ismael Everardo Bárcenas Patiño 1 , Edgard Benítez Guerrero 2 , José de Jesús Lavalle Martínez 3 , Guillermo Molero Castillo 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Veracruzana
3 Benemérita Universidad Autónoma de Puebla

Keywords: Presburger arithmetic, modal logics, automated reasoning, XPath, regular languages, interleaving
Abstract: The fully enriched µ-calculus is an expressive propositional modal logic with least and greatest fixed-points, nominals, inverse programs and graded modalities. Several fragments of this logic are known to be decidable in EXPTIME. However, the full logic is undecidable. Nevertheless, it has been recently shown that the fully enriched µ-calculus is decidable in EXPTIME when its models are finite trees. In the present work, we study the fully-enriched µ-calculus for trees extended with Presburger constraints. These constraints generalize graded modalities by restricting the number of children nodes with respect to Presburger arithmetic expressions. We show that this extension is decidable in EXPTIME. In addition, we also identify decidable extensions of regular tree languages (XML schemas) with interleaving and counting operators. This is achieved by alinear characterization in terms of the logic. Regular path queries (XPath) with Presburger constraints on children paths are also characterized. These results imply new optimal reasoning (emptiness, containment, equivalence) bounds on counting extensions of XPathqueries and XML schemas.
Evaluation of the biocompatibility of a PVA/SA scaffold with a human gingival fibroblast (HGF) by using electrochemical impedance spectroscopy
Miguel Ángel Hernández Gallegos 1 , Marco Antonio Álvarez Pérez 2 , Juan Genesca 3 , Karla Gómez 4 , Alba Covelo Villar 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Odontología
3 Universidad Nacional Autónoma de México, Facultad de Química
4 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: Biocompatibility, Electrochemical impedance, Culture cell, Nanofibre, Electrospinning, Sodium alginate
Abstract: The biocompatibility of human gingival fibroblasts (HGF) was evaluated in different concentrations of poly(vinyl alcohol) and sodium alginate (PVA/SA) nanofibres (3.5?wt% 4?wt% and 5?wt%). The PVA/SA nanofibres were deposited on the surface of an electrode microchip by using the electrospinning technique. Electrochemical impedance spectroscopy (EIS) was applied to measure the dielectric properties of each system. In order to provide a detailed analysis as well as a right physical interpretation of the EIS results, the data was fitted with an electric equivalent circuit based on the EIS and the microscopic assessments. The results registered three different time constants (TCs) of the PVA/SA scaffold which indicated different layers at different depths of the scaffold. The TCs changed their dielectric properties depending on the PVA/SA concentration. The 4?wt% system showed the highest biocompatibility properties, given that its resistance and electrochemical capacitance show the formation of a mature-stage cell interaction of HGF. The EIS data offers an exhaustive analysis of the biological activity of the cell response in real time to determine its biocompatibility features. Fluorescence analysis demonstrated a heterogeneous growth of the HGF on the PVA/SA scaffold surface.
Regular Expressions for Web Advertising Detection based on an Automatic Sliding Algorithm
Programming and Computer Software
D. Riaño 1 , R. Piñon 1 , Guillermo Molero Castillo 1 , Ismael Everardo Bárcenas Patiño 1 , Alejandro Velázquez Mena 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: This paper presents the automation of a Web advertising recognition algorithm, using regular expressions. Currently, the use of regular expressions, optical character recognition, Databases, and automation tests have been critical for multiple Software implementations. The tests were carried out in three Web browsers. As a result, the detection of advertisements in Spanish, that distract attention and that above all extract information from users was achieved. The main feature of the algorithm is that automatic and versatile execution does not require access to the code of the page in question and that in the future it can be an application with background operation. Being supported by optical character recognition gives us acceptable efficiency in detecting advertising. Thanks to this identification, it may be possible to generate different applications, both in favor of the user and the brands, always with the aim of improving current online marketing models.
Security Aspects for Rpl-Based Protocols: A Systematic Review in IoT
Applied Sciences
Karen Avila 1 , Daladier Jabba Molinares 1 , Javier Gómez 2
1 Universidad del Norte, Departamento de Ingeniería de Sistemas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: security in RPL, attacks in RPL, wireless sensor networks, internet of things
Abstract: The Internet of things (IoT) is a concept that has gained traction over the last decade. IoT networks have evolved around the wireless sensor network (WSN), and the following research looks at relevant IoT concepts and the different security issues that occur specifically at the network layer. This analysis is performed using a structured literature review (SLR). This form of bibliographic review has been a trend in recent years. Its strength is the performance of a bibliometric analysis that allows studying both trends in the line of research that you want to address and the relevant authors. This SLR reviews 53 proposals between 2011 and 2020, whose contribution is to mitigate attacks in the RPL (Routing Protocol for Low-Power and Lossy Networks) protocol. The revised proposals emerged after selecting keywords and databases in which to apply the search. Initially, approximately 380 research works appeared, for which it was necessary to continue using filters to refine the proposals to be included. After reading titles and abstracts, 53 papers were finally selected. In addition to analyzing the attacks mitigated in the RPL protocol, it is intended to identify the trend by which these attacks are reduced, as a result of the review, nine attacks have been found: rank, blackhole, selective forwarding, wormhole, DODAG (Destination-Oriented Directed Acyclic Graph) version number, DAO (Destination Advertisement Object) inconsistency, DIO (DODAG Information Object) suppression, Sybil, and sinkhole. Each of the 53 proposals analyzed in this review has an associated mitigation strategy, these strategies have been categorized into four groups, based on authentication or cryptography, based on network monitoring, based on secure parent node selection and other. According to the results, the authors?? primary mitigation strategy is based on network monitoring, with 30%. This review also identifies the principal authors and countries that need the development of this line of research.
A joint modulation-coding scheme and resource allocation in LTE uplink
Electronika ir elecktrotechnika
Amado Gutiérrez 1 , Víctor Rangel Licea 1 , Javier Gómez 1 , Robert Edwards 2 , David H. Covarrubias 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Loughborough University, 5G Research Centre
3 Centro de Investigación Científica y de Educación Superior de Ensenada

Keywords: Resource allocation, Scheduling algorithms, Modulation coding, LTE-A, SC-FDMA, 3GPP
Abstract: In Long Term Evolution (LTE) Resource Allocation Algorithms (RAAs) are an area of work where researchers are seeking to optimize the efficient use of scarce radio resources. The selection of an optimal Modulation and Coding Scheme (MCS) that allows LTE to adapt to channel conditions is a second area of ongoing work. In the wireless part of LTE, these two factors, RAA and MCS selection, are the most critical in optimization. In this paper, the performance of three resource allocation schemes is compared, and a new allocation scheme, Average MCS (AMCS) allocation, is proposed. AMCS is seen to outperform both "Minimum MCS (MMCS)? and "Average Signal to Interference and Noise Ratio MCS (SINR AMCS)? in terms of improvements to LTE Uplink (UL) performance. The three algorithms were implemented in the Vienna LTE-A Uplink Simulator v1.5.
A New Approach for PV Nodes Using an Efficient Backward/Forward Sweep Power Flow Technique
IEEE Latin America Transactions
Abner Suchite Remolino 1 , Héctor Francisco Ruiz Paredes 1 , Vicente Torres García 2
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Power flow, Backward-Forward Sweep, Distribution System, Distributed Generation
Abstract: Most of the distribution networks may contain reactive power sources such as distributed generators with reactive support, static VARs compensators or even switching capacitors. In this sense, it is necessary to have an appropriate and convenient model for controlled-voltage (PV) nodes to be applied in power flow distribution networks. On the other hand, the conventional power flow analysis has been an important tool for all power systems engineers. The nonlinear methods based on the Newton- Raphson method and its decoupled forms and the Gauss-Seidel with Ybus factorized method have been popular to nowadays. However, these methods have presented some convergence problems when are applied to distribution networks analysis. The reasons are the inherent characteristics of distribution networks, such as high r/x ratios, very low branch impedances, radial feeder configurations, among others. In this sense, the techniques based on Backward/Forward Sweep (BFS) methods for power flows have been widely applied in distribution systems. However, as above mentioned for controlled-voltage (PV) nodes some challenges in BFS power flow algorithms are presented, some authors have proposed hybrid methods, iterative methods, sensitivities matrix- based methods, among others. Unfortunately, those methods usually require complex formulations and long execution times. In this paper a new approach and easily controlled-voltage (PV) formulation joint with a simple power flows methodology, called LRSV method, is presented. The results show that this no-complex methodology permits to obtain better execution times, responses in a better way for different load, generation and configurations and some tests cases to demonstrate the effectiveness of the proposed methodology.
A New Varying Gain Exponent based Differentiator/Observer: An Efficient Balance between Linear and Sliding-Mode Algorithms
IEEE Transactions on Automatic Control
Malek Ghanes 1 , Jean Pierre Barbot 2 , Leonid Fridman Golredich 3 , Arie Levant 4 , Robert Boisliveau 5
1 Ecole Centrale of Nantes, Laboratory of Digital Sciences of Nantes
2 University of Nantes
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Tel-Aviv University, School of Mathematical Sciences

Keywords: Adaptive algorithms, observers, state estimation
Abstract: It is well known that the supertwisting algorithm is robust to matched perturbation but is sensitive to measurement noise. Contrary to this, the classical linear algorithm is less sensitive to measurement noise but less robust to perturbation. To combine both the good accuracy of the supertwisting algorithm with respect to perturbation and the good performance of the linear algorithm with respect to measurement noise, this article proposes a new differentiator/observer with a varying exponent gain α whose variation depends on the magnitude of measurement noise (high-frequency signal). When the magnitude of measurement noise increases (respectively, decreases) α tends to 1 (respectively, tends to 0.5) and the proposed differentiator/observer behaves as a linear algorithm (respectively, as a supertwisting algorithm). Thus, by one parameter α, the differentiator/observer can take care of high-frequency noise and matched perturbations. A complete stability analysis of the proposed differentiator/observer is provided. To highlight the applicability of the proposed methodology, the dedicated differentiator/observer is, respectively, validated on the electropneumatic actuator and electric machine test benches. These experimental results are compared to those of linear and supertwisting algorithms.
A practical model for the supply chain growth optimization for automotive fuels in Mexico
The Canadian Journal of Chemical Engineering
Rafael García Jolly 1 , Cecilia Martín del Campo 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: fuels-distribution, long-term planning, model simplification, supply chain optimization
Abstract: Profitability and energy efficiency depend on optimal operation of a supply chain network for automotive fuels in Mexico, even for clean energy expectations. This paper shows how decision?making for fuels?distribution network growth in Mexico points in the same direction, while the practical small optimization model, introduced in this paper, replaces a detailed model thereby offering great advantages to the analysts. The paper also describes the relevant strategies that were applied to ensure equivalences between the two models representing a supply chain. The model simplification not only reduces its size and computer time for execution but allows for the most relevant time reduction associated with preparing the data input to feed into the model, as well as in analyzing the results. Some distribution network growth options were evaluated by using both models with equivalent objective functions. Small model results give enough information for decision?making support. The use of new facilities and economic benefits are similar to those obtained with the complex model. The main issues to take care of are bottleneck identification and commodities differentiation. If a binding constraint is removed in the small model, similar results are seen in the complex model when a specific bottleneck is improved. This is the first time that a practical model is used to evaluate multiple scenarios of the complex automotive fuel distribution network in Mexico.
A simple approach for the force control of bilateral teleoperated manipulators with variable time delays
Control Engineering Practice
?scar Hernández Ortiz 1 , Marco Antonio Arteaga Pérez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bilateral systems, Time varying delays, Robot manipulators, Force reflection
Abstract: Local??remote teleoperated systems made up of robot manipulators have a large variety of applications, e. g. performing tasks in dangerous or inaccessible environments. They must provide the operator with the feeling of being in the remote environment and the ability of interacting with it. This objective is affected when time varying delays are present in the communication channel. In this work a control scheme for this kind of systems is proposed. It is shown that the local robot can be moved by the operator causing a (delayed) trajectory tracking in the remote manipulator. Should the later get in touch with the environment, the operator has some degree of delayed kinematic correspondence while the remote robot applies a force on the constraint surface tracking the (delayed) force commanded by the operator. The stability analysis is carried out under the assumptions that human and environment forces as well as their corresponding derivatives are bounded. Experimental results are provided to validate the proposed scheme, delivering a good performance both with rigid and elastic surfaces.
An outlier detection approach for water footprint assessments in shale formations: case Eagle Ford play (Texas)
Environmental Earth Sciences
Saúl Arciniega Esparza 1 , Antonio Hernández Espriú 2 , José Agustín Breña Naranjo 1 , Michael Young 3 , Adrián Pedrozo Acuña 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 The University of Texas at Austin, Jackson School of Geosciences

Keywords: Outliers, Geospatial analysis, Water use, Hydraulic fracturing, Eagle Ford, Shale gas
Abstract: The increasing trend on water use for hydraulic fracturing (HF) in multiple plays across the U.S. has raised the need to improve the HF water management model. Such approaches require good-quality datasets, particularly in water-stressed regions. In this work, we presented a QA/QC framework for HF data using an outlier detection methodology based on five univariate techniques: two interquartile ranges at 95 and 90% (PCTL95, PCTL90), the median absolute deviation (MAD) and Z score with thresholds of two and three times the standard deviation (2STD, 3STD). The cleaning techniques were tested using multiple variables from two data sources centered on the Eagle Ford play (EFP), Texas, for the period 2011??2017. Results suggest that the PCTL95 and MAD techniques are the best choices to remove long-tailed statistical distributions of different variables, classifying the minimum number of records as outliers. Overall, outliers represent 13??23% of the total HF water volume in the EFP. In addition, outliers highly impacted minimum and maximum HF water use values (min??max range of 0??47 m3/m and 5.3??24.6 m3/m of frac length, before and after the outlier removal process, respectively), that are frequently used as a proxy to develop future water??energy scenarios in early-stage plays. The data and framework presented here can be extended to other plays to improve water footprint estimates with similar conditions.
Assessment of the design effects on the structural performance of the Printed Circuit Heat Exchanger under very high temperature condition
Nuclear Engineering and Design
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 Circuit Heat Exchanger, Intermediate Heat Exchanger, Steam generator design, Thermal stress, Isochronous stress-strain curves
Abstract: The Printed Circuit Heat Exchanger (PCHE) is an important candidate to be used as Intermediate Heat Exchangers (IHX) in High Temperature Gas-cooled Reactor (HTGR) due to its advantages in terms of heat transfer and compactness. However, the complex operating conditions that include fluid temperatures around 1173 K and pressures higher than 7 MPa, cause the structural integrity of the device must be investigated in depth. In this work, a computational model of a PCHE with two-dimensional specification was developed using computational fluid dynamics and finite element method to evaluate the thermal and mechanical stresses. The simplification of the geometric domain was done considering the sensitivity of the stresses in the channels wall. The influence of the temperature gradient and the geometric parameters on the thermal stress is presented. The mechanical stress caused by pressure was evaluated for different geometric designs in the channel wall. The temperature gradient between channels was changed in a range from 10 K to 250 K, and the design was studied by means of parameters as channel diameter, plate thickness, ridge thickness and rounded tip radius. The isochronous strain??stress curves presented in the Draft ASME BPVC for use of the Alloy 617 (UNS N06617) at high temperature, were used to develop a multilinear plasticity material model. A proportional relationship between the thermal stress and the thermal gradient between channels was found. Opposite effects of the plate thickness and the ridge thickness on the thermal and mechanical stresses were evidenced. The increase of these produced a maximum thermal stress increment while the mechanical stress was reduced. The rounded tip radius was found as the main dimension to reduce both stresses reducing the stress concentration in this region. Based on the allowable stress of the structural material, safety ranges of the geometric parameters in the PCHE design were proposed. The plastic strain was also reduced with the roundness, but this displacement showed a great affectation with the time of service at high temperature condition.
Authors?? Reply To: (CI 20-0229) Comments on Design of controllers with arbitrary convergence time [Automatica 108710]
Anil Kumar Pal 1 , Shyam Kamal 1 , Shyam Krishna Nagar 1 , Bijnan Bandyopadhyay 1 , Leonid Fridman Golredich 2
1 Indian Institute of Technology, Systems and Control Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Barrier function-Based Variable Gain Super-Twisting Controller
IEEE Transactions on Automatic Control
Hussein Obeid 1 , Salah Laghrouche 1 , Leonid Fridman Golredich 2 , Yacine Chitour 3 , Mohamed Harmouche 4
1 Universite Bourgogne Franche-Comté/UTBM,
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 University Paris Saclay, L2S
4 Actility

Keywords: Adaptive super-twisting, barrier function, sliding mode
Abstract: In this article, a variable gain super-twisting algorithm based on a barrier function is proposed for a class of first order disturbed systems with uncertain control coefficient and whose disturbances derivatives are bounded but the upper bounds of those derivatives are unknown. The specific feature of this algorithm is that it can ensure the convergence of the output variable and maintain it in a predefined neighborhood of zero independent from the upper bound of the disturbances derivatives. Moreover, thanks to the structure of the barrier function, it forces the gain to decrease together with the output variable and the control signal follows the absolute value of the disturbances.
Characterization of germanium detectors for the first underground laboratory in Mexico
Journal of Instrumentation
Alexis Aguilar Arevalo 1 , S. Alvarado Mijangos 2 , Xavier Bertou 3 , Carlos Canet Miquel 4 , Miguel Angel Cruz Pérez 5 , Alexander Deisting 6 , Adriana Dias 6 , Juan Carlos D' Olivo 1 , Francisco Favela Pérez 1 , Estela A. Garcés 2 , Adiv González Muñoz 2 , Jaime Octavio Guerra Pulido 7 , Javier Mancera Alejandrez 7 , Daniel José Marín Lámbarri 2 , M. Martínez Montero 1 , Jocelyn Monroe 6 , C. Iván Ortega Hernández 1 , Sean Paling 8 , Simon Peeters 9 , D. Ruiz Esparza Rodríguez 2 , Paul Scovell 8 , Cenk Türko?lu 9 , Eric Vázquez Jáuregui 2 , Joseph Walding 6
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares
2 Universidad Nacional Autónoma de México, Instituto de Física
3 Centro Atómico Bariloche
4 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
5 Universidad Nacional Autónoma de México, Programa de Posgrado en Ciencias de la Tierra
6 University of London, Royal Holloway
7 Universidad Nacional Autónoma de México, Facultad de Ingeniería
8 Boulby Mine, Boulby Underground Laboratory
9 University of Sussex, Department of Physics and Astronomy

Keywords: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Gamma detectors; Gamma detectors (scintillators, CZT, HPGe, HgI etc)
Abstract: This article reports the characterization of two High Purity Germanium detectors performed by extracting and comparing their efficiencies using experimental data and Monte Carlo simulations. The efficiencies were calculated for pointlike ?-ray sources as well as for extended calibration sources. Characteristics of the detectors such as energy linearity, energy resolution and full energy peak efficiencies are reported from measurements performed on surface laboratories. The detectors will be deployed in a ?-ray assay facility that will be located in the first underground laboratory in Mexico, Laboratorio Subterráneo de Mineral del Chico (LABChico), in the Comarca Minera UNESCO Global Geopark [1].
Chattering analysis of Lipschitz continuous sliding-mode controllers
International Journal of Robust and Nonlinear Control
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.
Revisiting the flaws and pitfalls using simulation in the analysis of aviation capacity problems
Case Studies on Transport Policy
Miguel Mujica Mota 1 , Idalia Flores De La Mota 2
1 Amsterdam University of Applied Sciences, Aviation Academy
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Lelystad, Performance, Improvement, Optimization, Cleaning, Low cost, Carriers
Abstract: The aviation industry is a changing industry in which several factors influence the performance of the airport and the network of airports that are interconnected. Business models, technical operations in airspace and in the airfield, societal conditions among others are some of the ones that must be taken into account in order to get a full understanding of the cause-effect relationships that hinder the proper management of the system. In recent times with the evolution of the computer technology and the level of maturity of the algorithms used to simulate and analyse dynamic systems, simulation has gained more importance than before. Simulation approaches emerge as the ones that are able to take into account the stochastic nature of dynamic systems besides all the different factors that impact the systems under study. This is something that traditional analytical approaches could not evaluate and therefore under the constant change of the systems they lack of the proper flexibility to provide timely solutions. However with the popularity that simulation has gained, the different steps and good practices that must be taken into account are commonly forgotten when the simulation model is developed and then the system is analysed; in the particular case of the aviation industry this situation has gained particular importance. The current paper addresses some of the common flaws and pitfalls incurred when simulation is used for analysis of aeronautical systems. Pitfalls?? classification and suggestions for avoiding them are presented. Some flaws are exemplified through cases in which the conclusion from the analysis might differ depending on the angle of the analysis performed with the implications of different economic consequences for the decision makers. The main objective of this paper is that it serves as an eye-opener for a relatively novel researcher or practitioners in the art of simulation. It will serve for avoiding these common flaws when using simulation for addressing aviation problems.
Chirality control in white-light emitting 2D perovskites
Journal of Materials Chemistry C
Karla Trujillo Hernández 1 , Germán Rodríguez López 1 , Arian Espinosa Roa 1 , Jesús González Roque 1 , Ana Paulina Gómora Figueroa 2 , Weiguo Zhang 3 , Shiv Halasyamani 3 , Vojtech Jancik 4 , Milan Gembicky 5 , Giuseppe Pirruccio 6 , Diego Solis Ibarra 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 University of Houston, Departamento de Química
4 Universidad Nacional Autónoma de México, Instituto de Química
5 University of California, Department of Chemistry and Biochemistry
6 Universidad Nacional Autónoma de México, Instituto de Física

Abstract: The increased interest in white solid-state lighting devices addresses the urgent challenge to develop semiconductors with broad band emission. In recent years, low dimensional hybrid organic/inorganic lead perovskites have shown great potential as single white-light emitters. Herein, we show that it is possible to control the chirality of lead bromide perovskites by incorporating enantiopure (R or S) or racemic (RS) β-methylphenethylammonium. The incorporation of such cations allows us to control the chirality of the resulting materials and yields the first examples of 2D chiral perovskites that emit white light. Furthermore, we demonstrate that these materials exhibit second harmonic generation. Our results demonstrate the potential of this kind of materials for chiroptical applications and non-linear optics.
Continuous Twisting Algorithm for Third-Order Systems
IEEE Transactions on Automatic Control
Jesús Mendoza Avila 1 , 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 (HOSM) control, homogeneity, Lyapunov function (LF), robust control
Abstract: In this paper, two control schemes producing a continuous control signal are presented for a perturbed triple integrator: The continuous twisting algorithm (3-CTA) and the output feedback continuous twisting algorithm (3-OFCTA). The first one is a state feedback controller that ensures global finite-time stability of the origin, despite of Lipschitz, nonvanishing, and matched disturbances. It provides steady-state precision of fourth order of the output w.r.t. sampling step. The second one is an output feedback controller, which uses a third-order robust and exact differentiator as an observer. By requiring only information of the measurable output, the 3-OFCTA preserves all features of robustness, convergence, and precision of the state feedback 3-CTA. Moreover, it is proven that a separation principle applies, so that the gains of the controller and of the observer can be selected independently to assure stability.
Designing the underworld in Teotihuacan: Cave detection beneath the moon pyramid by ERT and ANT surveys
Journal of Archaeological Science
Denisse L. Argote Espino 1 , Andrés Tejero Andrade 2 , Martín Cárdenas Soto 2 , Gerardo Cifuentes Nava 3 , René E. Chávez Segura 3 , Esteban Hernández Quintero 3 , Alejandro García Serrano 2 , Verónica Ortega 4
1 Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Geofísica
4 Instituto Nacional de Antropología e Historia, Zona de Monumentos Arqueológicos de Teotihuacán

Keywords: Non-conventional ERT, ANT survey, Cave detection, Moon pyramid, Teotihuacan underworld, Mexico
Abstract: Teotihuacan is one of the largest pre-Hispanic cities established in central Mexico. Caves and tunnels have been previously found underneath two important edifices: the Sun and Quetzalcóatl pyramids, probably dedicated to religious ceremonies about the underworld, fertility and the creation of humankind. The main objective of this study was to provide hard evidence about the existence of a cavity beneath the Moon Pyramid, the second largest structure in the site. For this purpose, we applied ERT and ANT surveys, non-invasive geophysical techniques that permitted the identification of a void under the Moon Pyramid and some access tunnels. The historical impact of this discovery opens the discussion about the symbolic meaning of this pyramid and the origins of urban planning at the site.
Detecting differential ground displacements of civil structures in fast-subsiding metropolises with interferometric SAR and band-pass filtering
Scientific Reports
Darío Solano Rojas 1 , Shimon Wdowinski 2 , Enrique Cabral Cano 3 , Batuhan Osmano?lu 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Florida International University, Institute of Environment
3 Universidad Nacional Autónoma de México, Instituto de Geofísica
4 NASA Goddard Space Flight Center

Abstract: Ground displacements due to changes in soil conditions represent a threat to the stability of civil structures in many urban areas, worldwide. In fast-subsiding areas, regional subsidence (wavelength??~??1,000??s m) can be dominantly high and, consequently, mask other signals at local scales (wavelength??~??10??100??s m). Still, engineering and construction applications require a comprehensive knowledge of local-scale signals, which can threaten the stability of buildings and infrastructure. Here we present a new technique based on band-pass filters for uncovering local-scale signals hidden by regional subsidence as detected by interferometric SAR measurements. We apply our technique to a velocity field calculated from 21 high-resolution COSMO-SkyMed scenes acquired over Mexico City and obtain components of long (>??478 m), intermediate (42??478 m) and short (
Detection of Atrial Fibrillation from Single Lead ECG Signal Using Multirate Cosine Filter Bank and Deep Neural Network
Journal of Medical Systems
S. K. Ghosh 1 , Rajesh K. Tripathy 2 , Mario Roberto Arrieta Paternina 3 , Juan Gregorio Arrieta Paternina 4 , Alejandro Zamora Méndez 5 , Ganesh R. Naik 6
1 MLR Institute of Technology
2 Birla Institute of Technoloy and Science Pilani
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Sanatorio Güemes
5 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
6 Western Sydney University, MARCS Institute

Keywords: Atrial Fibrillation, Single Lead ECG, Multirate Cosine Filter Bank, Fractional Norm, Hierarchical Extreme Learning Machine
Abstract: Atrial fibrillation (AF) is a cardiac arrhythmia which is characterized based on the irregsular beating of atria, resulting in, the abnormal atrial patterns that are observed in the electrocardiogram (ECG) signal. The early detection of this pathology is very helpful for minimizing the chances of stroke, other heart-related disorders, and coronary artery diseases. This paper proposes a novel method for the detection of AF pathology based on the analysis of the ECG signal. The method adopts a multi-rate cosine filter bank architecture for the evaluation of coefficients from the ECG signal at different subbands, in turn, the Fractional norm (FN) feature is evaluated from the extracted coefficients at each subband. Then, the AF detection is carried out using a deep learning approach known as the Hierarchical Extreme Learning Machine (H-ELM) from the FN features. The proposed method is evaluated by considering normal and AF pathological ECG signals from public databases. The experimental results reveal that the proposed multi-rate cosine filter bank based on FN features is effective for the detection of AF pathology with an accuracy, sensitivity and specificity values of 99.40%, 98.77%, and 100%, respectively. The performance of the proposed diagnostic features of the ECG signal is compared with other existing features for the detection of AF. The low-frequency subband FN features found to be more significant with a difference of the mean values as 0.69 between normal and AF classes.
Detection of cover collapse doline and other epikarst features by multiple geophysical techniques, case study of tarimba cave, brazil
Yawar Hussain 1 , Rogério Elias Uagoda Soares 2 , Welitom Borges 2 , Renato Prado 3 , Omar Hamza 4 , Martín Cárdenas Soto 5 , Hans Balder Havenith 6
1 University of Brasilia, Department of Civil and Environmental Engineering
2 University of Brasilia, Department of Geography
3 Universidad de Sao Paulo, Instituto de Astronomía
4 University of Derby, College of Engineering and Technology
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería
6 Liege University, Geology Department

Keywords: ERT, SRS, three-layered stratigraphy, VLF-EM
Abstract: Reliable characterization of the karst system is essential for risk assessment where many associated hazards (e.g., cover-collapse dolines and groundwater pollution) can affect natural and built environments, threatening public safety. The use of multiple geophysical approaches may offer an improved way to investigate such cover-collapse sinkholes and aid in geohazard risk assessments. In this paper, covered karst, which has two types of shallow caves (vadose and fluvial) located in Tarimba (Goias, Brazil), was investigated using various geophysical methods to evaluate their efficiency in the delineation of the geometry of sediments filled sinkhole. The methods used for the investigation were Electrical Resistivity Tomography (ERT), Seismic Refraction Survey (SRS), Seismic Refraction Tomography (SRT) and the Very Low Frequency Electromagnetic (VLF-EM) method. The study developed several (2D) sections of the measured physical properties, including P-wave velocity and electrical resistivity, as well as the induced current (because of local bodies). For the analysis and processing of the data obtained from these methods, the following approaches were adopted: ERT inversion using a least-square scheme, Karous-Hjelt filter for VLF-EM data and time-distance curves and Vp cross-sections for the SRS. The refraction data analysis showed three-layered stratigraphy topsoil, claystone and carbonate bedrock, respectively. The findings obtained from ERT (three-layered stratigraphy and sediment-filled doline), as well as VLF-EM (fractured or filled caves as a positive anomaly), were found to be consistent with the actual field conditions. However, the SRS and SRT methods did not show the collapsed material and reached the limited the depth because of shorter profile lengths. The study provides a reasonable basis for the development of an integrated geophysical approach for site characterization of karst systems, particularly the perched tank and collapse doline.
Determinación de posible drenaje ácido de mina y caracterización de jales mineros provenientes de la mina Cerro de Mercado, Durango, México
Revista Internacional de Contaminación Ambiental
Fernando Benigno Salas Urviola 1 , Pedro Guadarrama Guzmán 2 , José Juan Gutiérrez Bazán 2 , Nadia García Luna 2 , Georgina Fernández Villagómez 2 , María Teresa Alarcón Herrera 3
1 Universidad Nacional del Altiplano Puno, Facultad de Ingeniería de Minas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Centro de Investigación en Materiales Avanzados

Keywords: ambiente, actividades antrópicas, metales pesados, alcalinidad, lixiviados
Abstract: La mina Cerro de Mercado, ubicada en el estado de Durango, México, ha almacenado jales durante el proceso de extracción de hematita y magnetita durante aproximadamente 80 años. La presente investigación tuvo como objetivo llevar caracterizar los jales de la presa Boleo Estrella de la mina Cerro de Mercado y determinar el potencial de generación de drenaje ácido, considerando la Norma Oficial Mexicana NOM-141-SEMARNAT-2003. El muestreo se realizó de acuerdo con la Norma Mexicana NMX-AA-132-SCFI-2006 y se obtuvieron 27 muestras en 16.2 ha de la superficie de la presa. Como resultado de la caracterización de dichos residuos, se obtuvieron valores de pH alcalinos y concentraciones mínimas de azufre y sulfatos; la relación potencial de neutralización/potencial de acidez fue mayor a 1.2, lo que indica que no son generadores potenciales de drenaje ácido. Por otro lado, la determinación de metales y metaloides considerados elementos potencialmente tóxicos presentes en las muestras de jales, evidencian la presencia de arsénico (As) y bario (Ba) en valores inferiores a los límites máximos permisibles (LMP) indicados en la NOM-157 SEMARNAT-2009; asimismo, el 22.2 % de dichas muestras está dentro de los LMP establecidos para cromo (Cr) y el 77.8 % se halla ligeramente por encima de los LMP. En el 66.7 % de los jales muestreados no se detectó antimonio (Sb); sin embargo, el 33.3 % restante contiene Sb en cantidades superiores a los LMP. De acuerdo con el estudio realizado, se puede deducir que los jales analizados no generan drenaje ácido y en las condiciones ambientales actuales, aun con la presencia de Cr y Sb, no presentan peligro para el ambiente.
Dosimetry and calorimetry performance of a scientific CMOS camera for environmental monitoring
Alexis Aguilar Arevalo 1 , Xavier Bertou 2 , Carlos Canet Miquel 3 , Miguel Angel Cruz Pérez 4 , Alexander Deisting 5 , Adriana Dias 5 , Juan Carlos D' Olivo 1 , Francisco Favela Pérez 1 , Estela A. Garcés 6 , Adiv González Muñoz 6 , Jaime Octavio Guerra Pulido 7 , Javier Mancera Alejandrez 7 , Daniel José Marín Lámbarri 6 , Mauricio Martínez Montero 1 , Jocelyn Monroe 5 , Sean Paling 8 , Simon Peeters 9 , Paul Scovell 8 , Cenk Türko?lu 9 , Eric Vázquez Jáuregui 6 , Joseph Walding 5
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares
2 Centro Atómico Bariloche
3 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
4 Universidad Nacional Autónoma de México, Programa de Posgrado en Ciencias de la Tierra
5 University of London, Royal Holloway
6 Universidad Nacional Autónoma de México, Instituto de Física
7 Universidad Nacional Autónoma de México, Facultad de Ingeniería
8 Boulby Mine, Boulby Underground Laboratory
9 University of Sussex, Department of Physics and Astronomy

Keywords: lead-210, commercial CMOS cameras, scientific CMOS sensor , gamma detection, X-ray detection, lead in drinking water, dosimetry, world health organisation
Abstract: This paper explores the prospect of CMOS devices to assay lead in drinking water, using calorimetry. Lead occurs together with traces of radioisotopes, e.g., 210Pb, producing γ-emissions with energies ranging from 10 keV to several 100 keV when they decay; this range is detectable in silicon sensors. In this paper we test a CMOS camera (Oxford Instruments Neo 5.5) for its general performance as a detector of X-rays and low energy γ-rays and assess its sensitivity relative to the World Health Organization upper limit on lead in drinking water. Energies from 6 keV to 60 keV are examined. The CMOS camera has a linear energy response over this range and its energy resolution is for the most part slightly better than 2%. The Neo sCMOS is not sensitive to X-rays with energies below ?10 keV. The smallest detectable rate is 40±3mHz, corresponding to an incident activity on the chip of 7±4Bq. The estimation of the incident activity sensitivity from the detected activity relies on geometric acceptance and the measured efficiency vs. energy. We report the efficiency measurement, which is 0.08(2)% (0.0011(2)%) at 26.3keV (59.5keV). Taking calorimetric information into account we measure a minimal detectable rate of 4±1mHz (1.5±1mHz) for 26.3keV (59.5keV) γ-rays, which corresponds to an incident activity of 1.0±6Bq (57±33Bq). Toy Monte Carlo and Geant4 simulations agree with these results. These results show this CMOS sensor is well-suited as a γ- and X-ray detector with sensitivity at the few to 100 ppb level for 210Pb in a sample.
EEG-Rhythm Specific Taylor-Fourier Filter Bank Implemented with O-Splines for the Detection of Epilepsy Using EEG Signals
IEEE Sensors Journal
José Antonio De la O Serna 1 , Mario Roberto Arrieta Paternina 2 , Alejandro Zamora Méndez 3 , Rajesh K. Tripathy 4 , Ram Blas Pachoni 5
1 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
4 Birla Institute of Technoloy and Science Pilani
5 Institute of Technology Indore

Keywords: Seizure, electroencephalogram, Taylor-Fourier filter-bank, O-splines, least-square SVM, accuracy
Abstract: The neurological disorder which is associated with the abnormal electrical activity generated from the brain causing seizures is typically termed as epilepsy. The automated detection and classification of epilepsy based on the analysis of the electroencephalogram (EEG) signal are highly required for its early diagnosis. In this paper, we have developed an EEG-rhythm specific Taylor-Fourier filter-bank implemented with O-splines for the detection and classification of epilepsy from the EEG signal. The energy features are evaluated from the Taylor-Fourier sub-band signals of the EEG signal. The classifiers such as K-nearest neighbor (KNN) and least square support vector machine (SVM) are employed for the classification of normal, seizure-free and seizure from the Taylor-Fourier EEG-band energy (TFEBE) features. The experimental results demonstrate that, for the classification of normal, seizure-free, and seizure classes, the least square SVM classifier has an overall accuracy value of 94.88% using the EEG signals from the Bonn university database. The proposed EEG rhythm specific Taylor-Fourier filter-bank with O-splines can be implemented in real-time for the detection of epileptic seizures from EEG signals.
Effect of a Ni-P coating on the corrosion resistance of an additive manufacturing carbon steel immersed in a 0.1 M NaCl solution
Materials Letters
Day Gilberto Agredo Diaz 1 , Arturo Barba Pingarrón 2 , Jhon Jairo Olaya Florez 1 , Jesús Rafael González Parra 2 , Javier Cervantes Cabello 2 , Irma Angarita Moncaleano 1 , Alba Covelo Villar 2 , Miguel Ángel Hernández Gallegos 2
1 Universidad Nacional de Colombia, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Additive manufacturing, Electroless nickel plating, Electrochemical noise, EIS, X-ray diffraction
Abstract: In this work, it has been possible to deposit a Ni-P alloy by electroless nickel plating on the surface of a low carbon steel sample, produced by additive manufacturing. The samples were characterized by SEM, EDS, XRD, white light interferometry, Vickers microhardness, EIS, and ENM techniques. A coating of an amorphous nature is obtained at a deposition rate of 9.19 µm/h, with high homogeneity, average roughness of 86.52 nm, good adhesion to the substrate, and a hardness of the order of 500 HV. The electrochemical characterization allows evidence of a significant increase in corrosion resistance for the coated material with a noise resistance of 20 kω-cm2 after 576 h of evaluation.
Empirical relationships of groundwater head??salinity response to variations of sea level and vertical recharge in coastal confined karst aquifers
Hydrogeology Journal
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: Groundwater statistics, coastal aquifers, karst, salt-water/fresh-water relations
Abstract: Coastal aquifers are characterized by a mixing zone with freshwater??saltwater interactions, which have a strong relationship with hydrological forcings such as astronomical and storm tides, aquifer recharge and pumping effects. These forcings govern the aquifer hydraulic head, the spatial distribution of groundwater salinity and the saline interface position. This work is an empirical evaluation through time-series analysis between aquifer head and groundwater salinity associated with the sea-level dynamics and the aquifer recharge. Groundwater pressure, temperature and salinity were measured in a confined aquifer in the northwest coast of Yucatan (México) during May 2017??May 2018, along with precipitation. Cross-correlation and linear Pearson correlation (r) analyses were performed with the data time series, separating astronomical and meteorological tides and vertical recharge effects. The results show that the astronomical and meteorological tides are directly correlated with the aquifer head response (0.71??< r ??0.7) is a more important forcing than the vertical recharge (with 0.5??< r
Evaluation of the corrosion resistance of a Ni-P coating deposited on additive manufacturing steel: A dataset
Data in Brief
Day Gilberto Agredo Diaz 1 , Arturo Barba Pingarrón 2 , Jhon Jairo Olaya Florez 1 , Jesús Rafael González Parra 2 , Javier Cervantes Cabello 2 , Irma Angarita Moncaleano 1 , Alba Covelo Villar 2 , Miguel Ángel Hernández Gallegos 2
1 Universidad Nacional de Colombia, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Additive manufacturing, Electroless nickel plating, Electrochemical noise, EIS, Microhardness, X-ray diffraction
Abstract: This article presents the data set obtained for the research work entitled "Effect of a Ni-P coating on the corrosion resistance of an additive manufacturing carbon steel immersed in a 0.1 M NaCl solution? [1]. Microstructural, mechanical, and electrochemical characterization (using the electrochemical impedance and electrochemical noise spectroscopy technique) is performed on a material obtained by additive manufacturing and the influence of a Ni-P coating on it. The layer sizes and hardness of the substrate are measured, as well as the thickness of the coating and its hardness, values for corrosion resistance, resistance to electrochemical noise and location indices are calculated. The data show an adequate deposition rate for the type of coating, as well as the increase in corrosion resistance when the coating is applied to the steel by additive manufacturing.
Fault tolerant control based on continuous twisting algorithms of a 3-DoF helicopter prototype
Control Engineering Practice
Ulises Pérez Ventura 1 , Leonid Fridman Golredich 1 , E. Capello 2 , E. Punta 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Politecnico di Torino, Department of Mechanical and Aerospace Engineering
3 Politecnico di Torino, CNR-IEIIT

Keywords: Fault detection and isolation, Fault tolerant control, Sliding-mode control
Abstract: Fault tolerant controllers, based on the Continuous Twisting Algorithm (CTA), are designed for robust stabilization of a three-degree-of-freedom (3-DoF) helicopter prototype. Voltage variations (faults) in the actuators are detected and isolated by means of residual-based equations and exploiting the third-order sliding mode differentiator (SMD). Proposed fault detection and isolation (FDI) scheme is tested with intermittent and persistent faults induced by software. A unknown-input sliding mode observer (SMO) is developed to compare and highlight the performance of the proposed FDI-SMD respect to the classic FDI-SMO. Finally, simulations and real-time experiments confirm that CTA-based controllers counteract additive faults. Filtering the signals from residual equations is suggested in order to mitigate the effects of noises and neglected (parasitic) dynamics on the detectors.
Biomechanical behavior of bone tissue in spine instrumentation
Cirugía y Cirujanos
Armando Alpízar Aguirre 1 , Raide Alfonso González Carbonell 2 , Armando Ortiz Prado 3 , Víctor Hugo Jacobo Armendáriz 3 , Osvaldo Ruiz Cervantes 3 , Lázaro Morales Acosta 3
1 Instituto Nacional de Rahabilitación, Departamento de Cirugía de Columna
2 Universidad de Camagüey, Facultad de Electromecánica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Osteoporosis, Pedicular fixation with screws, Stress, Biomechanics
Abstract: Background: The mechanical fixation of the spine in patients with osteoporotic vertebral degeneration is a challenge for surgeons, the vertebrae selected to insert the screws may fail, endangering health and even patient??s life.Objective: The objective of the study was to study the effect of the variation of the bone density in the bone-screw interface from a three-dimensional model of the lumbar section. Materials and methods: The finite element method was used to model the behavior of the lumbar vertebral section when applying compression loads. Results: The stresses between 2 and 3 MPa were located on the contact surface with the screw, both in the vertebral body and in the apophysis, being slightly higher in the vertebral body. Conclusions: Regardless of bone density, the contact zones between the screws are susceptible to bone tissue failure. The posterior half of the vertebral body was the most sensitive to high values of stress, while in the areas furthest from the axis of the screw stress tended to their minimum.
Flame-sprayed Zn-Al coatings on ABS without chemical surface preparation
Materials Letters
Day Gilberto Agredo Diaz 1 , Raúl Valdez Navarro 2 , Nicolas Ortiz Godoy 1 , Arturo Barba Pingarrón 2 , Jesús Rafael González Parra 2 , Jhon Jairo Olaya Florez 1 , Magdalena Trujillo Barragán 2 , Irma Angarita Moncaleano 1 , Cesar Armando Ortiz Otalora 3
1 Universidad Nacional de Colombia, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Pedagógica y Tecnológica de Colombia, Facultad de Ciencias

Keywords: ABS, Electrical conductivity, Metallization, SEM, Wire flame spray, XRD
Abstract: Metallization of polymeric materials is a process that manages to combine the properties of polymers and metals, to expand its range of applications. In this research, the deposition of a Zn-Al alloy on a polymeric substrate (ABS) using wire flame spray was carried out, with a predominant advantage by not using chemical surface preparation processes, thus obtaining materials at low cost, friendly to the environment, without affecting the properties of the substrate, avoiding its degradation by temperature, and gaining a level of electrical conductivity appropriate to nature of the coatings. Substrate roughness is measured by interferometry, coating morphology by SEM, the composition by EDS, structure by XRD, adhesion by Pull-Off, and electrical resistivity is evaluated using the 4-point test. The SEM results show a coating with a thickness of the order of 89 µm, homogeneous in its composition with a Zn and Al crystalline structure, an adhesion strength of 888 N, with a porosity of 0.87% with an average pore size of 10 µm. The electrical conductivity study of the coated material shows a good electrical response, with a value of 2682 S/m.
A hybrid system for optimizing enrichment and gadolinia distributions in BWR fuel lattices
Progress in Nuclear Energy
José Luis Montes Tadeo 1 , Raúl Perusquía Del Cueto 1 , David A. Pelta 2 , Juan Luis François Lacouture 3 , Juan José Ortiz Servin 1 , Cecilia Martín del Campo 3 , Alejandro Castillo 1
1 Instituto Nacional de Investigaciones Nucleares
2 Universidad de Granada, ETSI Informática y de Telecomunicaciones
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fuel lattice design, Optimization, BWR fuel, Ant colony system
Abstract: A new approach for optimizing the enrichment and gadolinia distribution in a typical BWR fuel lattice is presented. It takes advantage of potentialities of two different methodologies: the Ant-Colony-System (ACS) meta-heuristic technique and S15 a method based on knowledge. The S15 method was programmed in such a way that can reduce the objective function systematically in a few iterations. In this way, a human expert was essentially substituted by the system. S15 takes advantage of the ACS's ability for exploring the searching space. Reciprocally, ACS can use the directed search generated by S15. The system was tested using typical fuel lattices from both transition and equilibrium operation cycles in a BWR. The lattice physics code CASMO-4 was used to generate the parameters of the objective function. As a result of the hybridization process of the aforementioned methodologies, the obtained results overcame those obtained using different heuristic techniques applied to the same problem. All imposed goals or requirements were improved or fulfilled: on average, the obtained local power peaking factor is 7.57% lower than the reference one, the obtained value for the initial average U-235 enrichment is, on average, 1.12% lower than the reference one, the precision in obtaining the k-infinity's requirement was improved by about 33%, and the gadolinia content was fulfilled in all the cases. Finally, the needed total wall time for obtaining a suitable solution was substantially reduced using the proposed system.
Flood and contain: An optimized repeal-based flooding algorithm for wireless ad hoc and sensor networks
Javier Gómez 1 , Martha Montes de Oca 2 , José Jaime Camacho Escoto 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Panamericana, Facultad de Ingeniería

Keywords: routing, wireless sensor networks, Ad Hoc, flooding, IoT, resource discovery
Abstract: Flooding is a simple yet reliable way of discovering resources in wireless ad hoc networks such as mobile ad hoc networks (MANETs), ad hoc sensors, and recently, IoT networks. However, its operation is resource-intensive, especially in densely populated networks. Several approaches can be found in the literature to reduce the impact of flooding. Many of these approaches follow a repeal-based operation, chasing and stopping further propagation of flooding packets once the target is found. However, repeal-based protocols might end up transmitting even more packets than the original flooding. This work characterizes a maximum repeal-flooding boundary beyond which it is counterproductive to chase the original flooding. We present the Flood and Contain (F&C) algorithm, a method that can quickly establish the maximum repeal-flooding boundary for each node while making no assumptions on the underlying network. F&C??s packet overhead increases linearly with the hop count up to the maximum repeal-flooding boundary, in which case there is no attempt to chase the original flooding. In this latter case, F&C generates only as many packets as the original flooding. Simulations show that, on average, F&C reduces the total flooding overhead (compared to traditional flooding) up to 35 percent once considering all possible destinations, with only a slight increase in resource discovery latency, and it outperforms all other repeal-based protocols, particularly for longer routes.
Design of controllers with arbitrary convergence time
Anil Kumar Pal 1 , Shyam Kamal 1 , Shyam Krishna Nagar 1 , Bijnan Bandyopadhyay 1 , Leonid Fridman Golredich 2
1 Indian Institute of Technology, Systems and Control Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Nonlinear control, Nonautonomous system, Backstepping, Lyapunov stability, Free-will arbitrary time stability
Abstract: In this paper, a method for new controller design ensuring the arbitrary time of convergence is proposed. The sufficient condition for Lyapunov stability is also given for this arbitrary chosen time stable system. Disturbances have been taken care of by introducing sliding mode control in the design approach. Finally, the efficacy of the proposed method is illustrated through a practical system, viz., magnetic suspension system.
Evolución geoquímica de la Formación Eagle Ford y su rol como roca generadora de gas y aceite en Coahuila, NE México
Boletín de la Sociedad Geológica Mexicana
.http://dx.doi.org/10.18268/ BSGM2020v72n2a141219
Alberto Herrera Palomo 1 , Luis Martínez 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Université de Strasbourg

Keywords: Eagle Ford, kerogen, shale gas, Total Organic Carbon, hydrocarbons
Abstract: To determine the quality of the Eagle Ford Formation, on the Burro - Picachos platform, as a hydrocarbon generating rock and its implication in the context of an unconventional type of deposit (shale gas), they were analyzed with the adaptation of the method Dykstra - Parson for permeability, the average values weighted to the thickness of COT, Tmax, S2 / S3 and PP 1.42 to 6.1) of four wells located in the southeast portion of the border line of the state of Coahuila, in the range of 1410 m 2460 m deep. Thanks to the COT content (1.05 to 2.44%), present in the study area, the Eagle Ford Formation can be classified as a hydrocarbon generator, with a regular to excellent quality. The Tmax data (443 ° C at 484 ° C), locate the generating rock in a phase of early to late thermal maturity, with the exception of the Habano-1 well that reached over maturity. The potential producer (PP) of the area is between weak to medium and the calculation of the type of hydrocarbon generated (S2 / S3) indicates the presence of oil and gas in the formation. This could limit the existence of oil at maximum depths of 1820 m in the northern portion of the studied area, if the hydrogen index (IH) is observed. Oxygen index (IO), its evolution indicates that the predominant is a mixture formed mainly of type III and II which can be interpreted as the precursors of the gas and oil found Of four exploratory wells analyzed, only one presents geochemical characteristics with cut-off values similar to those proposed in shale gas development in the Barnett Basin.
Geometry optimization of top metallic contacts in a solar cell using the constructal design method
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: solar cell, metallic contact, constructal design, structure
Abstract: Sunlight is a natural resource that can be harnessed by the photovoltaic conversion of sunlight into electricity-utilizing solar cells. The production of most common solar cells consists of a homojunction of a p-type and n-type silicon. The p??n junction is realized by the diffusion of impurities through one surface of the wafer. Silicon wafers have a typical dimension of 156 ? 156 mm2 and a thickness of 0.15??0.2 mm. Groups of 50??100 solar cells are electrically connected and encapsulated to form a module. The required area for interconnection does not contribute to power generation, and the performance of larger area devices usually suffers from higher resistive losses. In the present work, a theoretical model of the geometric arrangement of the top contact metallic electrodes branched network in a photovoltaic cell is developed. The network structure of the electrodes is obtained from applying the constructal design methodology by the minimization of the overall resistance. As a result, the optimal lengths and geometrical relationships of an electrode branching network with a branching angle are determined. A geometric distribution of the electrode network on the solar cell analyzed by the total resistance of every level of branching is defined. The top metallic contact network presents a tree-shaped geometric arrangement with the main objective of covering a generation area for an enhanced collection of the generated electrical current. The theoretical results obtained are expressed as the total voltage of the arrangement and the lengths of the branched electrode network.
Coupled Monte Carlo-CFD analysis of heat transfer phenomena in a supercritical water reactor fuel assembly
Annals of Nuclear Energy
Landy Castro 1 , Juan Luis François Lacouture 1 , Carlos F. García Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de La Habana, Instituto Superior de Tecnologías y Ciencias Aplicadas

Keywords: Heat transfer, Supercritical water, Coupled calculation, CFD, SCWR, HTD
Abstract: In this paper coupled calculations with the CFD code ANSYS-CFX-19.0 and the Monte Carlo neutronics code MCNP6 were performed to analyze the heat transfer in supercritical water flowing through the typical fuel assembly of the high-performance light water reactor (HPLWR), in order to improve the characterization of the heat transfer phenomena in supercritical water under non-uniform axial heat flux distributions that is characteristic of this type of reactor. To check the capability of the CFX model to predict the thermal-hydraulic behavior of supercritical water, the computational results were compared with two experimental data. The Shitsma?s experiment in the presence of heat transfer deterioration (HTD) using four low-Re turbulence models (SST, k-ω, BSL-k-ω, and ω-Reynolds Stress) and the Wanǵs experiment in absence of HTD, using the low-Re-SST and the scalable-wall-function-SSG turbulence models. In the presence of the HTD phenomenon, results showed the high dependency of the wall temperature with the turbulence model and the turbulent Prandtl number selected. In the absence of HTD, both turbulence models studied adequately predicted the behavior of the wall temperature distribution. For the coupled neutronic/thermal-hydraulic analysis of the typical HPLWR fuel assembly, the low-Re SST turbulence model and the Prt = 1.5 were used. Different axial profiles of heat flux generated in the fuel rods were obtained for the different power values studied. For the analyzed conditions, the presence of HTD in the lower zone of the fuel assembly was observed. In addition, the results showed a strong non-uniformity of the circumferential surface cladding temperature distribution in the sub-channel located at the corner of the fuel assembly; a new curvature radius of the assembly box corner was proposed to obtain a well homogenized circumferential wall temperature distribution.
H2 yielding rate comparison in a warm plasma reactor and thermal cracking furnace
International Journal of Hydrogen Energy
Joel Pacheco 1 , Ricardo Valdivia 1 , Marquidia Pacheco 1 , Abel Clemente 2
1 Instituto Nacional de Investigaciones Nucleares, Laboratorio de Aplicaciones de Plasma
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: GHG, Hydrogen, Syngas yielding, Warm plasma, Conversion, Selectivity
Abstract: Climate change increases the odds of worsening drought and generating extreme weather events, being the poorest nations the most vulnerable. The emission of greenhouse gases (GHG) from anthropogenic activities have a considerable impact on climate change; in particular, the emission of carbon dioxide (CO2) and methane (CH4) has the weightiest and most aggressive impact on the Earth. An emergent solution is to convert those specific gases into syngas (CO + H2) by using plasma technology; which offers reduced specific energy, and it is capable to produce very energetic species with instantaneous sequential chemical reactions. This work aims to validate the production of syngas comprising acetylene (C2H2) from the treatment of Biogas samples and a mixture composed of CH4, CO2, and N2 using warm plasma reactors. Specific energy (SE) and Energy Conversion Efficiency (ECE) were obtained in the function of experimental settings, showing the potential of the warm plasma technology on GHG treatment. Additionally, a comparison between warm plasma and thermal cracking processes has shown that H2 is generated more than 200 times faster and in a bigger quantity (more than 8 times) in a warm plasma than for conventional heating process.
3D Hermite Transform Optical Flow Estimation in Left Ventricle CT Sequences
Carlos Mira 1 , Ernesto Moya Albor 2 , Boris Escalante Ramírez 1 , Jimena Olveres 3 , Jorge Brieva 2 , Enrique Vallejo Venegas 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Panamericana, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
4 Centro Médico ABC, Cardiología

Keywords: bio-inspired computing, motion estimation, optical flow, differential method, steered hermite transform, cardiac CT imaging, algorithms
Abstract: Heart diseases are the most important causes of death in the world and over the years, the study of cardiac movement has been carried out mainly in two dimensions, however, it is important to consider that the deformations due to the movement of the heart occur in a three-dimensional space. The 3D+t analysis allows to describe most of the motions of the heart, for example, the twisting motion that takes place on every beat cycle that allows us identifying abnormalities of the heart walls. Therefore, it is necessary to develop algorithms that help specialists understand the cardiac movement. In this work, we developed a new approach to determine the cardiac movement in three dimensions using a differential optical flow approach in which we use the steered Hermite transform (SHT) which allows us to decompose cardiac volumes taking advantage of it as a model of the human vision system (HVS). Our proposal was tested in complete cardiac computed tomography (CT) volumes ( 3D+t ), as well as its respective left ventricular segmentation. The robustness to noise was tested with good results. The evaluation of the results was carried out through errors in forwarding reconstruction, from the volume at time t to time t+1 using the optical flow obtained (interpolation errors). The parameters were tuned extensively. In the case of the 2D algorithm, the interpolation errors and normalized interpolation errors are very close and below the values reported in ground truth flows. In the case of the 3D algorithm, the results were compared with another similar method in 3D and the interpolation errors remained below 0.1. These results of interpolation errors for complete cardiac volumes and the left ventricle are shown graphically for clarity. Finally, a series of graphs are observed where the characteristic of contraction and dilation of the left ventricle is evident through the representation of the 3D optical flow.
Horizontal projectile motion: Comparing free fall and drag resistance
Revista Mexicana de Física
Ricardo Yáñez Valdez 1 , P. A. Gómez Valdez 1 , F. de Armas Rivero 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Newtons Laws, drag force, projectile
Abstract: The motion of a particle that is projected into a resistant medium and subjected to a uniform gravitational field is considered. The drag force that acts upon the particle within the medium is proportional to the particle??s speed, the density of the medium, and the cross-section area of the projectile. We review the problem of a horizontal motion with a drag force that is linear in speed. The problem is formulated in terms of particle speed, mass, height, time, and expelled gas velocity. The equations of motion are solved analytically, and a case study is discussed. As a result, we obtain the deviation of the projectile as a function of time because of the expelled gases with or without drag force.
Enhanced ferromagnetic and electric properties of multiferroic BiFeO3 by doping with Ca
Journal of Alloys and Compounds
Félix Sánchez De Jesús 1 , Ana María Bolarín Miró 1 , Claudia Alicia Cortés Escobedo 2 , Arturo Barba Pingarrón 3 , Fernando Pedro García 1
1 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
2 Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Ca-doping, BiFeO3 doped, Multiferroic, High-energy ball milling
Abstract: We report the dependence of magnetic and electric properties with the substitution of Bi3+ by Ca2+ into the crystal structure of multiferroic calcium doped BiFeO3 for obtaining Bi1-xCaxFeO3, 0 ? x ? 0.10 Stoichiometric mixtures of Bi2O3, Fe2O3 and CaO were mixed and milled for 5 h using a ball to powder weight ratio of 10:1 by high-energy ball milling. The obtained powder was pressed at 900 MPa to obtain cylindrical pellets and sintered at 800 °C for 2 h. X-ray diffraction and Rietveld refinement were used to evaluate the effect of Ca2+ on the crystal structure and to determinate the phase transition from rhombohedral α-BiFeO3 (R3c) to orthorhombic β-BiFeO3 (Pbnm). In addition, vibrating sample magnetometry (VSM) was used to have knowledge of magnetic order: antiferromagnetism and ferromagnetism were identified for α-BiFeO3 and β-BiFeO3, respectively. Dielectric tests determinate Debye-type relaxation for samples with the rhombohedral crystal structure and no Debye type relaxations for orthorhombic samples. Differences in AC conductivity of rhombohedral samples show different mechanism compared with the conductivity of orthorhombic samples. Ferromagnetic and electrical properties of synthesized materials show a strong correlation with the lattice distortions induced by the ionic ratio between Ca2+ and Bi3+. The effect of Ca2+ over leakage current has an interesting response, an increase of Ca2+ reduce one magnitude order the leakage current for α-BiFeO3 samples; though for β-BiFeO3 samples increase of Ca2+ raise the leakage current in one magnitude order.
Hydrodynamics rheological impact of an oscillatory electroosmotic flow on a mass transfer process in a microcapillary with a reversible wall reaction
Physics of Fluids
G. Mederos 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

Abstract: In this work, we carry out a theoretical analysis of the mass transport rate through a long microcapillary, with a reactive wall, connecting two reservoirs with different concentrations of some electro-neutral solute, caused by an oscillatory electroosmotic flow of a Jeffreys fluid. The mass transport enhancement relative to that caused only by molecular diffusion is found to be a function of the following dimensionless parameters: the angular Reynolds number Rω; the Deborah numbers De1 and De2, associated with the relaxation and retardation times, respectively; the Schmidt number Sc; the Damköhler number Da; the partition number ? ? ; the tidal displacement ΔZ; and the ratio between the radius of the microcapillary and the Debye length ? κ . We find that for a viscoelastic fluid, there exists a resonant behavior of the mass transfer rate when the angular Reynolds number assumes specific values. In this context, we evidence that the interaction between the fluid elasticity and the oscillatory character of the flow enhances the mass transfer rate up to several orders of magnitude compared with that caused by an oscillatory electroosmotic flow of a Newtonian fluid. We also found that the microcapillary wall??s reactive characteristics, manifested through the Damköhler number and the dimensionless partitioning coefficient, could enhance or diminish the mass transfer rate depending on the interplay of the other dimensionless parameters involved in the analysis.
Influence of boron content on the solidification structure, magnetic properties and hot mechanical behavior in an advanced as-cast twip steel
Antonio Salas Reyes 1 , Gerardo Altamirano Guerrero 2 , J. F. Chávez Alcalá 3 , Arturo Barba Pingarrón 4 , I. A. Figueroa 5 , Ana María Bolarín Miró 6 , Félix Sánchez De Jesús 6 , R. Deaquino Lara 7 , Armando Salinas Rodríguez 7
1 Universidad Nacional Autónoma de México, Facultad de Química
2 Tecnológico Nacional de México, Instituto Tecnológico de Saltillo
3 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Química e Industrias Extractivas
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería
5 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
6 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
7 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados

Keywords: TWIP steel, boron micro-addition, incoherent solidification, dendritic structure, ferromagnetic behavior, hot ductility
Abstract: This research work reports the effect of boron micro-additions (180 and 470 ppm) on the solidification structure, magnetic properties and hot ductility behavior of an advanced low-carbon highly alloyed twinning-induced plasticity (TWIP) steel. For this purpose, three experimental TWIP steels were fabricated by melting commercial raw materials and casting into metallic molds. Solidification structure was characterized by means of optical and scanning electron microscopy techniques, and a statistical study was carried out to measure dendrite features. A vibrating sample magnetometer was used, at room temperature, to determine magnetic properties, and a X-ray diffraction analysis was performed in order to identify the related phases during magnetic measurements. Finally, the hot ductility in the as-cast condition was evaluated at 700, 900 and 1100 °C, under a constant strain rate of 0.001 s??1. The results indicate that boron micro-additions cause an overall refining solidification structure and austenitic grain size. However, as the boron content increases, segregation of this element promotes formation of ferrite and ε-martensite, leading to ferromagnetic behavior. Nonetheless, with subsequent hot- and cold-rolling, the single austenitic phase is achieved, and this behavior is eliminated. Hot tensile tests revealed that boron micro-addition is beneficial to the hot ductility behavior. The greatest influence was observed for the higher concentration of boron (470 ppm). In comparison with the steel without boron content, the reduction of area (RA) is more than the triple of the hot workability during straining at 900 °C. Thus, present results demonstrate that boron micro-addition has an excellent potential for refining dendritic microstructure and improving the hot-deformation behavior of present low-carbon highly alloyed TWIP steel.
Machining Parameters and Toolpath Productivity Optimization Using a Factorial Design and Fit Regression Model in Face Milling and Drilling Operations
Mathematical Problems in Engineering
Gustavo M. Minquiz 1 , Vicente Borja Ramírez 2 , Marcelo López Parra 2 , Alejandro Cuauhtémoc Ramírez Reivich 2 , Leopoldo Ruiz Huerta 3 , Roberto C. Ambrosio Lázaro 1 , Alejandro Shigeru Yamamoto Sánchez 4 , Héctor Vázquez Leal 5 , María Esther Pavon Solana 1 , J. Flores Méndez 1
1 Benemérita Universidad Autónoma de Puebla
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
4 Sandvik, Coromant México
5 Universidad Veracruzana, Facultad de Instrumentación Electrónica

Abstract: Very commonly, a mechanical workpiece manufactured industrially includes more than one machining operation. Even more, it is a common activity of programmers, who make a decision in this regard every time a milling and drilling operation is performed. This research is focused on better understanding the power behavior for face milling and drilling manufacturing operations, and the methodology followed was the design of experiments (DOEs) with the cutting parameters set in combination with toolpath evaluation available in commercial software, having as main goal to get a predictive power equation validated in two ways, linear or nonlinear, and understanding the energy consumption and the quality surface in face milling and final diameter in drilling. The results show that it is possible to find difference in a power demand of 1.52??kW to 3.9??kW in the same workpiece, depending on the operations (face milling or drilling), cutting parameters, and toolpath chosen. Additionally, the equations modelled showed acceptable values to predict the power, with values higher than 0.05 which is the significance level for the nonlinear and linear equations with an R square predictive of 98.36. Some conclusions established that optimization of the cutting parameters combined with toolpath strategies can represent an energy consumption optimization higher than 0.21% and the importance to try to find an energy consumption balance when a workpiece has different milling operations.
Magnetodielectric coupling tuning through domain wall charge accumulation in co-doped BiFeO3 with Sr2+ and Mn3+
Journal of Alloys and Compounds
F. Pedro García 1 , Félix Sánchez De Jesús 2 , Ana María Bolarín Miró 2 , Arturo Barba Pingarrón 1 , Claudia Alicia Cortés Escobedo 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
3 Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica

Keywords: Magnetodielectric effect, Multiferroic, BiFeO3Sr2+ and Mn3+ co-doping, High-energy ball milling
Abstract: We report the effect of Sr2+ and Mn3+ co-doping BiFeO3 on the crystal structure and the multiferroic properties of Bi0.95Sr0.05Fe1-xMnxO3 (0.0 = x ? 0.4, Δx = 0.1) powders, synthesized by assisted high-energy ball milling of stoichiometric mixtures of Bi2O3, Fe2O3, SrO, and Mn2O3; the powders were pressed at 900 MPa and sintered at 800 °C. X-ray diffraction and Rietveld refinement reveal the effect of Sr2+ and Mn3+ on the crystal structure. These elements act as inhibitors of secondary phases. Magnetic behavior, obtained using vibrating sample magnetometry shows antiferromagnetic order and an increase in magnetic susceptibility, due to slight differences in ionic radii and low crystal structure distortion. All the samples show high relative permittivity values, which is augmented by doping with Sr2+ and Mn3+ ions furthermore, the doping increases dielectric dissipation factor; it is attributed to their interaction with different oxidation state cations like Fe3+, Fe2+, Mn3+, Mn2+, Bi3+, and Sr2+, into the crystal structure of BiFeO3. Additionally, it was found increments of the electrical conductivity, due to the domain-wall charge accumulation phenomenon. In the same way, the relative permittivity improves as an effect of domain-walls conductivity, induced by Sr and Mn co-doping. The magnetodielectric effect presents a change in mechanism origin, from core-dominated (grain) to interface-dominated (electrode-dielectric, and grain-grain boundary), as a result of domain-wall charge accumulation.
Mapping small and medium-sized water reservoirs using Sentinel-1A: A case study in Chiapas, Mexico
Journal of Applied Remote Sensing
Alejandra A. López Caloca 1 , Boris Escalante Ramírez 2 , Pilar Henao 1
1 Centro de Investigación en Geografía y Geomática "Ing. Jorge L. Tamayo"" A.C."
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Synthetic aperture radar, image segmentation, statistical analysis, correlation function, image acquisition, image processing, inspection
Abstract: Using satellite data to study small water bodies (SWB) and medium-sized water bodies (MSWB) is extremely useful for understanding their status, how to conserve them as water reservoirs, and their vulnerability to climate variability. The images studied in our work correspond to different-sized lagoons located in areas with high and low topography in a tropical region of Chiapas, Mexico. Our research project delineates SWB and MSWB. For this analysis, we considered water bodies to be uniform regions in a synthetic aperture radar image. The robustness of the method was determined based on an analysis of the morphologies of 23 lagoons. Several methods, including Hermite transform, were analyzed and compared with other image denoising methods used to improve speckle reduction. To obtain additional spatial information for image classification, we analyzed texture using the gray-level co-occurrence matrix. The results indicate that the Hermite filter is the best method for identifying water bodies. The advantage of this filter is the identification of local patterns such as edges and lines. It also preserves and improves aspects related to the homogeneity of water bodies, using the Hermite coefficient selection criteria for local pattern feature selection/extraction. The lake water extent products demonstrate that Sentinel-1 is useful for identifying SWB in this study area. The results show very high detection of water bodies, with adequate detection for water bodies larger than 2 ha, and an area accuracy of 80%.
Miniaturized Frequency-Selective Surfaces Based on Monolithically Integrated Components
IEEE Transactions on Antennas and Propagation
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: Frequency-selective surfaces (FSSs), microfabrication technology, miniaturization, periodic structures
Abstract: In this article, a novel approach to design low-profile miniaturized frequency-selective surfaces (FSSs) is proposed. The effective miniaturization of the FSS elements, based on squarering-slot resonators, is accomplished by reactively loading the FSS unit cell with monolithically integrated components. The reactive components, such as capacitors and inductors embedded in the resonant unit cell, are fabricated using a multistep thin-film process based on benzocyclobutene (BCB) resin. The capacitors are built as planar metal-insulator-metal structures using an ultra-thin dielectric layer of BCB, while the multiturn inductors are fabricated as planar spiral structures with two metal layers and BCB as an interlevel dielectric for crossover. The advantages of the proposed approach are the capability to obtain large values of capacitances and inductances within small areas with low parasitics as well as the benefits in cost reduction and easy fabrication by using a planar microfabrication process. A component value variation analysis is performed to study the effect of fabrication tolerances in the reflection and transmission coefficients of the FSS when non-identical small cells are obtained. It has been experimentally validated that a 2.46 mm unit cell resonates at 4.175 GHz with transmission loss of 0.86 dB, achieving a miniaturization level of λ/29.
Misadjustment of diurnal expression of core temperature and locomotor activity in lactating rabbits associated with maternal over-nutrition before and during pregnancy
Plos One
Erika Navarrete 1 , Andrea Díaz Villaseñor 1 , Georgina Díaz 1 , Ana María Salazar 1 , Rodrigo Montúfar Chaveznava 2 , Patricia Ostrosky Wegman 1 , Ivette Caldelas 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones Biomédicas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Metabolic parameters ranging from circulating nutrient levels and substrate utilization to energy expenditure and thermogenesis are temporally modulated by the circadian timing system. During critical embryonic developmental periods, maternal over-nutrition could alter key elements in different tissues associated with the generation of circadian rhythmicity, compromising normal rhythmicity development. To address this issue, we determine whether maternal over-nutrition leads to alterations in the development of circadian rhythmicity at physiological and behavioral levels in the offspring. For this, female rabbits were fed a standard diet (SD) or high-fat and carbohydrate diet (HFCD) before mating and during gestation. Core body temperature and gross locomotor activity were continuously recorded in newborn rabbits, daily measurements of body weight and the amount of milk ingested was carried out. At the end of lactation, tissue samples, including brown adipose tissue (BAT) and white adipose tissue (WAT), were obtained for determining the expression of uncoupling protein-1 (UCP1) and cell death-inducing DNA fragmentation factor-like effector A (CIDEA) genes. HFCD pups exhibited conspicuous differences in the development of the daily rhythm of temperature and locomotor activity compared to the SD pups, including a significant increase in the daily mean core temperature, changes in the time when temperature or activity remains above the average, shifts in the acrophase, decrease in the duration and intensity of the anticipatory rise previous to nursing, and changes in frequency of the rhythms. HFCD pups exhibited a significant increase in BAT thermogenesis markers, and a decrease of these markers in WAT, indicating more heat generation by brown adipocytes and alterations in the browning process. These results indicate that maternal over-nutrition alters offspring homeostatic and chronostatic regulation at the physiological and behavioral levels. Further studies are needed to determine whether these alterations are associated with the changes in the organization of the circadian system of the progeny.
Morphological estimation of cellularity on neo-adjuvant treated breast cancer histological images
Journal of Imaging
Mauricio Alberto Ortega Ruiz 1 , Cefa Karaba? 2 , Víctor García Garduño 3 , Constantino Carlos Reyes Aldasoro 2
1 Universidad del Valle de México, Departamento de Ingeniería
2 University of London, Computer Science and Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: neo-adjuvant treatment, digital pathology, tumour cellularity, machine learning
Abstract: This paper describes a methodology that extracts key morphological features from histological breast cancer images in order to automatically assess Tumour Cellularity (TC) in Neo-Adjuvant treatment (NAT) patients. The response to NAT gives information on therapy efficacy and it is measured by the residual cancer burden index, which is composed of two metrics: TC and the assessment of lymph nodes. The data consist of whole slide images (WSIs) of breast tissue stained with Hematoxylin and Eosin (H&E) released in the 2019 SPIE Breast Challenge. The methodology proposed is based on traditional computer vision methods (K-means, watershed segmentation, Otsu??s binarisation, and morphological operations), implementing colour separation, segmentation, and feature extraction. Correlation between morphological features and the residual TC after a NAT treatment was examined. Linear regression and statistical methods were used and twenty-two key morphological parameters from the nuclei, epithelial region, and the full image were extracted. Subsequently, an automated TC assessment that was based on Machine Learning (ML) algorithms was implemented and trained with only selected key parameters. The methodology was validated with the score assigned by two pathologists through the intra-class correlation coefficient (ICC). The selection of key morphological parameters improved the results reported over other ML methodologies and it was very close to deep learning methodologies. These results are encouraging, as a traditionally-trained ML algorithm can be useful when limited training data are available preventing the use of deep learning approaches.
Petrographic, geochemical and isotopic (Sr??Nd??Pb??Os) study of plio-quaternary volcanics and the tertiary basement in the Jorullo-Tacámbaro area, Michoacán-Guanajuato Volcanic Field, Mexico
Journal of Petrology
Marie Noëlle Guilbaud 1 , Claus Siebe 1 , Christine Rasoazanamparany 2 , Elisabeth Widom 2 , Sergio Salinas 3 , Renato Castro Govea 4
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Miami University, Departmente of Geology and Environmental Earth Science
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituo Mexicano del Petróleo

Keywords: alkaline, calc-alkaline, continental arc, lamprophyre, Trans-Mexican Volcanic Belt
Abstract: The origin of the large diversity of rock types erupted along the subduction-related Trans-Mexican Volcanic Belt (TMVB) remains highly debated. In particular, several hypotheses have been proposed to explain the contemporary eruption of calc-alkaline and alkaline magmas along the belt. The Michoacán-Guanajuato Volcanic Field (MGVF) is an atypical, vast region of monogenetic activity located in the western-central part of the TMVB. Here we present new petrographic, geochemical, and isotopic (Sr??Nd??Pb??Os) data on recent volcanics in the Jorullo-Tacámbaro area that is the closest to the oceanic trench. TMVB-related volcanics in this area are Plio-Quaternary (<5??Ma) and mainly form a calc-alkaline series from basalts to dacites, with rare (<5??vol. %) alkaline rocks that range from trachybasalts to trachydacites, and transitional samples. Crystal textures are consistent with rapid crystallization at shallow depth and processes of mixing of similar magma batches (magma recharge). All of the samples exhibit an arc-type trace element pattern. Alkaline and transitional magmas have higher Na2O and K2O, lower Al2O3, and higher concentrations in incompatible elements (e.g. Sr, K, Ba, Th, Ce, P) compared to calc-alkaline rocks. Calc-alkaline rocks are similar isotopically to transitional and alkaline samples, except for a few low 87Sr/86Sr samples. Sr, Nd and Pb isotopes do not correlate with MgO or 187Os/188Os, indicating that they were not significantly influenced by crustal contamination. Isotopic and trace-element systematics suggest that the Tacámbaro magmas are produced by melting of a mantle wedge fluxed by fluids derived from a mixture of subducted sediments and altered oceanic crust. Alkaline and transitional magmas can be derived from a lower degree of partial melting of a similar source to that of the calc-alkaline rocks, whereas the few low 87Sr/86Sr calc-alkaline rocks require a lower proportion of fluid derived from oceanic sediments and crust. Volcanism at the trenchward edge of the MGVF was thus driven purely by subduction during the last 5??Ma, hence discarding slab rollback in this sector of the TMVB.
Control de posición y fuerza con estimación de masa para sistemas cooperativos
Revista Iberoamericana de Automática e Informática Industrial
Pablo Sánchez Sánchez 1 , Marco Antonio Arteaga Pérez 2
1 Benemérita Universidad Autónoma de Puebla, Facultad de Electrónica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Robots cooperativos, control adaptable, control de fuerza, restricciones holonómicas, función tangente hiperbólica
Abstract: La manipulación cooperativa de un objeto por dos o más brazos robóticos requiere controlar tanto el movimiento del objeto como las fuerzas ejercidas por los manipuladores. En términos de cinemática y estática, el enfoque elegido se basa en la denominada formulación simétrica. Se diseña un algoritmo de control que utiliza una modificación del método híbrido de torque computarizado basado en el Principio de Ortogonalización. Además, la masa del objeto se estima calculando la fuerza aplicada por cada efector final para sostener el objeto. El método propuesto es una extensión natural del esquema de control adaptativo previamente reportado para manipuladores geométricamente restringidos. La prueba de estabilidad se desarrolla utilizando la teoría de Lyapunov. Se presentan resultados experimentales.
Predicción de drenaje ácido de mina, jales de la mina La Prieta, Chihuahua, México
Revista Internacional de Contaminación Ambiental
Fernando Benigno Salas Urviola 1 , Pedro Guadarrama Guzmán 2 , Georgina Fernández Villagómez 2 , Jesús Fidel González Sánchez 2 , Luis Adrián Barraza Torres 2
1 Universidad Nacional del Altiplano Puno, Facultad de Ingeniería de Minas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: drenaje ácido de mina, jales mineros, predicción
Abstract: La mina La Prieta, Chihuahua, México, fue explotada ampliamente (plata, plomo y cobre) desde la época del virreinato hasta su cierre; por consiguiente, se acumularon grandes cantidades de jales o relaves, producto del procesamiento metalúrgico. Estos jales pueden producir drenaje ácido de mina debido a las reacciones de oxidación e hidrólisis. Con el objetivo de predecir si los jales son generadores de drenaje ácido, se realizó la caracterización de las muestras de jales y la determinación de la posibilidad de generar acidez. Los valores de pH hallados fueron ligeramente alcalinos (7.8-8.4). Por otro lado, los sulfatos y el azufre total se determinaron mediante los métodos turbidimétrico e infrarrojo, respectivamente. Cabe mencionar que la concentración de azufre total estuvo por debajo del límite de detección del equipo Leco S-144DR y las concentraciones de azufre en forma de sulfatos fueron mínimas. La caracterización mineralógica mostró que sólo en tres muestras se encontró pirita, y en bajos porcentajes. Los minerales calcita y dolomita presentes en el yacimiento tipo skarn intervienen en la neutralización del drenaje ácido de la mina y disminuyen la movilidad de la mayoría de los metales y metaloides tóxicos.
Self-energy, line tension and bow-out of grain boundary dislocation sources
International Journal of Plasticity
Rafael Schouwenaars Franssens 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: A. Dislocations, A. Grain boundaries, B. Polycrystalline material, C. Analytic functions, C. Prescribed curvature problem
Abstract: Experimental observation and numerical modelling of plastic deformation of sub-micrometre grains show that the importance of grain boundary dislocation sources (GBDS) increases as the grain size dg decreases below 1 μm. Grain boundary (GB) ledges and grain boundary dislocations (GBD) define limiting cases of the general concept of disconnections. Although the former have often been identified as potential GBDS, the latter are generally used in models for GBD-nucleation. In absence of pre-existing GBDs, (i.e. boundary ledges or disconnection-free boundaries), conservation of the Burgers vector imposes the creation of a residual GBD-segment when a mobile segment is emitted. This GBD exercises a back-stress on the emitted dislocation, which was analysed using two approaches. The first one calculates the self-energy (SE) of a dislocation loop consisting of a straight segment and a circular arc with arbitrary angle 2α and radius r, providing new results in the elastic theory of dislocations. The second model uses a line-tension (LT) approach, calculating the curvature of the dislocation as a function of the local stress field, defining a prescribed curvature problem. The models provide different details about the activation of GBDS but are remarkably compatible. They predict that the GB-segment formed upon initial bow-out will become shorter until the loop is cut off at the root, leaving a closed dislocation loop within the grain. This defines a GB-equivalent for the classical Frank-Read (FR) source, with a low activation energy for the smallest source lengths.
Semiglobal Finite-Time Trajectory Tracking Realization for Disturbed Nonlinear Systems via Higher-Order Sliding Modes
IEEE Transactions on Automatic Control
Chuanlin Zhang 1 , Jun Yang 2 , Yunda Yan 2 , Leonid Fridman Golredich 3 , Shihua Li 2
1 Shanghai University of Electric Power, College of Automation Engineering
2 Southeast University, School of Automation
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Active disturbance attenuation, finite-time control, higher-order sliding mode (HOSM), homogeneous system theory, semiglobal stability
Abstract: This paper investigates an alternative nonrecursive finite-time trajectory tracking control methodology for a class of nonlinear systems in the presence of general mismatched disturbances. By integrating a finite-time disturbance feedforward decoupling process via higher-order sliding modes, it is shown that, a novel nonrecursive design framework resulting a simpler controller expression and easier gain tuning mechanism is presented. A new feature is that a quasi-linear inherent nonsmooth control law could be constructed straightforwardly from the system information, which is essentially detached from the determination of a series of virtual controllers. Moreover, by proposing a less ambitious semiglobal tracking control objective, the synthesis procedure can be achieved without restrictive nonlinear growth constraints. Explicit stability analysis is given to ensure the theoretical justification. A numerical example and an application to the speed regulation of permanent magnet synchronous motor are provided to illustrate the simplicity and effectiveness of the proposed nonrecursive control design approach.
Sensing of Environmental Variables for the Analysis of Indoor Air Pollution
International Journal of Advanced Computer Science and Applications
Jaime Xilot 1 , Guillermo Molero Castillo 2 , Benítez Guerrero 1 , Ismael Everardo Bárcenas Patiño 2
1 Universidad Veracruzana, Facultad de Estadistica e infromatica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Air pollution, Ambient Intelligence (AmI), indoor air quality, wireless sensor network
Abstract: Ambient intelligence systems try to perceive the environment and react, proactively and pervasively to improve peoples environmental conditions. A current challenge in Ambient intelligence is trying to mitigate environmental risks that affect global public health, such as increasing air pollution. This paper presents the analysis of some environmental variables related to indoor air pollutants, such as CO, PM 2.5, PM 10, humidity and temperature; all of these captured in a university environment. The environmental measurements were carried out through a wireless sensor network consisting of two nodes. The cloud computing service, that is, ThingSpeak, was used as the storage medium. With this network, the presence of pollutants in the study area were detected with concentration levels within the permitted ranges, as well as its correlation with the atmospheric variables of temperature and humidity. The implementation of the sensor network allowed the capture of data in a transparent and non-intrusive way, and the analysis allowed the understanding of the behavior of pollutants in indoor spaces, where air circulation is limited, which in the face of high levels of pollution can be harmful to human health.
Static sliding mode control of systems with arbitrary relative degree by using artificial delays
IEEE Transactions on Automatic Control
Jing Xu 1 , Emilia Fridman 2 , Leonid Fridman Golredich 3 , Yugang Niu 1
1 East China University of Science and Technology, Key Laboratory of Advanced Control and Optimization for Chemical Process
2 Tel Aviv University, School of Electrical Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Sliding mode control, static feedback, time-delay systems
Abstract: Static output-feedback stabilization of systems with relative degree n with matched disturbances is considered. Assuming that the system is controllable, a static output-feedback sliding mode controller is designed, where the output derivatives up to the order (n-1) are approximated by using the current and the delayed values of the output. Numerical examples illustrate the efficiency of the method.
Surface nanostructuring of a cualbe shape memory alloy produces a 10.3 ± 0.6 gpa nanohardness martensite microstructure
Carlos Gabriel Figueroa Alcántara 1 , Víctor Hugo Jacobo Armendáriz 2 , Jacinto Cortés Pérez 1 , Rafael Schouwenaars Franssens 2
1 Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Aragón
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: advanced alloy materials, materials synthesis and characterisation, shape memory alloy, surface modification, severe plastic deformation, martensite, nanohardness
Abstract: Severe plastic deformation (SPD) has led to the discovery of ever stronger materials, either by bulk modification or by surface deformation under sliding contact. These processes increase the strength of an alloy through the transformation of the deformation substructure into submicrometric grains or twins. Here, surface SPD was induced by plastic deformation under frictional contact with a spherical tool in a hot rolled CuAlBe-shape memory alloy. This created a microstructure consisting of a few course martensite variants and ultrafine intersecting bands of secondary martensite and/or austenite, increasing the nanohardness of hot-rolled material from 2.6 to 10.3 GPa. In as-cast material the increase was from 2.4 to 5 GPa. The friction coefficient and surface damage were significantly higher in the hot rolled condition. Metallographic evidence showed that hot rolling was not followed by recrystallisation. This means that a remaining dislocation substructure can lock the martensite and impedes back-transformation to austenite. In the as-cast material, a very fine but softer austenite microstructure was found. The observed difference in properties provides an opportunity to fine-tune the process either for optimal wear resistance or for maximum surface hardness. The modified hot-rolled material possesses the highest hardness obtained to date in nanostructured non-ferrous alloys.
Wave reflection by a submerged cycloidal breakwater in presence of a beach with different depth profiles
Wave Motion
S. Bahena Jiménez 1 , Eric Gustavo Bautista Godínez 1 , Federico Méndez Lavielle 2 , A. Quesada Torres 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Submerged breakwater, Zero-reflection, Coastal engineering, Short waves, Cycloidal breakwater
Abstract: In this work, formulas for the reflection and transmission coefficients of one-dimensional linear water waves propagating over a submerged structure with a cycloidal cross section in presence of a sloping beach are determined. In the specialized literature, the previous coefficients are obtained mainly for the limit of linear water waves, considering that the water depth upstream and downstream of the structure is flat. For the analysis, we have obtained an approximate analytical solution to the dimensionless Modified Mild-Slope Equation, which models the interactions of a wide range of water waves, from short waves to long waves. The results shown that the presence of small breakwaters not always generate increments on the reflection coefficients, but on the contrary case they contribute to the reflection of the waves decreasing, which is due to the interference of energy that exists between the inclined beach and the structure. To validate the approximate analytical solution, we present a comparison against analytical solutions reported in the specialized literature, obtained with the aid of linear long wave theory, and a numerical solution, all the solutions adjust properly. Results of this study are expected to be used by coastal engineers for preliminary feasibility and desk design of submerged cycloidal breakwaters.
Wheel Slip Control for the Electric Vehicle with In-Wheel Motors: Variable Structure and Sliding Mode Methods
IEEE Transactions on Industrial Electronics
Dzmitry Savitski 1 , Valentin Ivanov 2 , Klaus Augsburg 2 , Tomoki Emmei 3 , Hiroyuki Fuse 3 , Hiroshi Fujimoto 3 , Leonid Fridman Golredich 4
1 Pforzcheim, Arrival Germany GmbH
2 Technical University of Ilmenau, Automotive Engineering Group
3 The University of Tokyo, Graduate School of Frontier Sciences
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Continuous twisting algorithm (CTA), electric vehicle (EV), in-wheel motors (IWMs), sliding mode control, variable structure systems, wheel slip control (WSC)
Abstract: The article introduces four variants of the controller design for a continuous wheel slip control (WSC) system developed for the full electric vehicle equipped with individual in-wheel motors for each wheel. The study includes explanation of the WSC architecture, design of controllers, and their validation on road tests. The investigated WSC design variants use variable-structure proportional-integral, first-order sliding mode, integral sliding mode controllers as well as continuous twisting algorithm. To compare their functionality, a benchmark procedure is proposed based on several performance factors responsible for driving safety, driving comfort, and control quality. The controllers are compared by the results of validation tests done on low-friction road surface.
Zero dynamics assignment and its applications to the stabilization of linear time-varying systems
Debbie Hernández 1 , Eli Abraham Vázquez 2 , Leonid Fridman Golredich 3 , Branislava Peruniči? Draženovi? 4
1 Instituto Tecnológico de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 University of Sarajevo, Faculty of Electrical Engineering

Keywords: Zero assignment, Time-varying MIMO systems, Pole placement, Robust control, Sliding-mode control
Abstract: An algorithm to select an output for desired vector relative degree, which is not restricted to be uniform (the same for all outputs), and zero dynamics in linear time-varying (LTV) multi-input multi-output (MIMO) systems is proposed. The proposed algorithm is developed under reasonable assumptions of uniform (with respect to time) and lexicography-fixed controllability (with some choice of fixed controllability indices) and is inspired by a generalization of the Ackermann??s formula. One application of the proposed algorithm is the context of higher-order sliding-mode control for perturbed LTV MIMO systems, achieving finite-time stability. The developed algorithm also provides an extension of the classical Ackermann??Utkin formula for outputs of uniform relative degree one and includes the design of flat outputs for LTV MIMO systems. Hence other application is the feedback controller design for trajectory tracking task. Finally, a complete HOSM methodology is provided and tested in an LTV model of the non-holonomic car.
Internet of things and industry 4.0 applied in the delivery system for the bicipuma bike-sharing system in UNAM-Mexico
Procedia Manufacturing
A. M. Silva Pérez 1 , V. Rodríguez Olvera 1 , C. Cerrud García 1 , F. I. Anguiano Soler 1 , Idalia Flores De La Mota 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: delivery, management, simulation, IoT, App's
Abstract: This paper analyzes the delivery of units by the users of Bicipuma so that the accomplishment of this task is done quickly and efficiently for the modules with the highest demand. The aim of the proposal is to create a delivery system by aids of simulation in which the times required are minimal, improving the quality of service to users. Also describes the development of a system for the loan service of BiciPuma bicycles implementing elements of Industry 4.0 such as automation and the internet of things (IoT) that allow reducing bicycle losses and the number of accidents caused due to carelessness when traveling along the cycle path. In addition, an App is proposed that allows the user to be informed about the existence of bicycles in the different stations and the service conditions of the stations.
Paleofloristic diversity and paleoenvironmental interpretation of new Cisuralian localities in the south-central sector of the Anticlinorium of Huayacocotla, Hidalgo, Mexico
María Patricia Velasco De León 1 , Erika Lourdes Ortiz Martínez 1 , Diego Enrique Lozano Carmona 1 , Miguel Ángel Flores Barragán 1 , Javier Arellano Gil 2 , Noé Santillán Piña 2
1 Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Zaragoza
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Lepidodendrales, Peltaspermales, Paleobotany, Eustatic changes, Transitional environment, Permian
Abstract: The Anticlinorium of Huayacocotla has several outcrops of geological and paleontological importance. However, reports of localities with paleoflora have been scarce so far. In this study, we report three new localities in the Cisuralian, the diversity and composition of which lead us to propose that the paleoflora may have been derived from vegetation that grew in an arid environment with seasonal wetness. The plant remains from the localities of Papaxtla and Calnali are highly transported and their diversity indicates the presence of several groups of plants that were shared with the La Virgen locality, which yielded the best preserved plant fossils. Changes in paleoenvironmental conditions indicate that the preservation of the flora was affected by the tectonic evolution of the region associated with sea level changes. The data presented here increase our knowledge of both the Cisuralian fossil flora and paleoenvironment in the south-central region of the Huayacocotla Anticlinorium, Hidalgo state.
Frequency response curves for a Mooney-Rivlin hyperelastic microbubble oscillating as a contrast agent in an acoustic pressure field
Jorge Luis Naude De la Llave 1 , César Yepez Terreros 1 , Federico Méndez Lavielle 1 , Margarita Navarrete Montesinos 2 , R. F. Cienfuegos Pelaes 3 , Fátima Moumtadi 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica

Keywords: Ultrasound contrast agent, Hyperelastic, Microbubble, Multiple scales, Rayleigh-plesset
Abstract: In this work, we have developed numerical simulations and weakly nonlinear analysis based on the multiple-scales perturbation technique for a coated microbubble that performs radial pulsations subject to an acoustic pressure disturbance in the far-field and whose encapsulated hyperelastic material obeys the Mooney-Rivlin equation. Departing from an elastic coating as a hyperelastic shell of finite thickness, we assume eventually that the shell is of very small thickness in comparison with the microbubble radius. Under this condition, we then perform weakly nonlinear analysis, to identify resonance conditions for small pressure disturbances of the acoustic field. In parallel and also for the limit of small thickness, we have carried out numerical simulations of the radial motion of the microbubble, identifying the onset of limit cycles via the construction of Poincare maps. Under both schemes, we have recognized the importance of two dimensionless hyperelastic parameters that dictate the main behavior of the oscillations: and . Decreasing the values of these parameters, the resonance conditions are drastically amplified, which is an expected result because of the weak rigidity of the hyperelastic solid, prevails. In this manner, we suggest that moderate values for these previous parameters can be widely advisable when, in medical diagnostic applications, we are applying microbubbles as contrast agents. Therefore, we recommend widely the use of shell softens, because in this case the amplitude of radial pulsation is always amplified.
Complex Networks of the Air Passenger Traffic in Monterrey´s Airport
Transportation Researh Procedia
Olivia Sashiko Shirai Reyna 1 , Idalia Flores De La Mota 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: complex networks, visibility, time series, forecast, air passengers
Abstract: Nowadays, the air passenger traffic has been increasing, becoming an excellent, viable and reachable option for many people. This causes that airports may require an efficient organization to serve both, the companies that use the facilities and the passengers. In addition, it is important to consider that the amount of information that is generated may not be easy to analyse, sometimes because the managers don´t know all the information that they have, or they don´t know how much this information can help the business or what they can do with all these data. Therefore, in this work, we perform an analysis of the information obtained from Monterrey´s airport (domestic and international passengers), using the methodology of Complex Networks Analysis. Also, with the results obtained, we will seek to put forward improvements in the service of this type of facilities, and the infrastructure.
Finite-time control for rigid robots with bounded input torques
Control Engineering Practice
Javier Pliego Jiménez 1 , Marco Antonio Arteaga Pérez 2 , Mauro López Rodríguez 2
1 CICESE-CONACYT, Divsión de Física Aplicada
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Robot manipulator, terminal sliding surface, robust control, finite-time trajectory tracking
Abstract: The problem of finite-time trajectory tracking of robot manipulators with uncertain dynamics, external bounded disturbances, and bounded torque inputs is addressed in this paper. In order to achieve finite-time convergence a nonlinear control algorithm based on a second-order sliding mode controller in combination with nonsingular terminal sliding mode is proposed. The proposed controller also exploits the properties of the hyperbolic tangent function. As a result, the control algorithm generates a continuous bounded signal. In addition, the controller structure is simple since it does not require the knowledge of the robot dynamic model. Experimental results are provided to show the performance of the proposed control algorithm.
Numerical simulation of the aqueous humor flow in the eye drainage system; a healthy and pathological condition comparison
Medical Engineering & Physics
G. J. Martínez Sánchez 1 , C. Escobar Del Pozo 2 , J. A. Rocha Medina 3 , Jorge Luis Naude De la Llave 1 , A. Brambila Solorzano 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Colima, Facultad de Ingeniería Mecánica y Eléctrica
3 Petroleos Mexicanos, Hospital Central del Norte

Keywords: Anterior chamber, glaucoma, collector channels, intraocular pressure, segmental flow
Abstract: The present work describes the motion of aqueous humor through the anterior chamber and the trabecular drainage system, considering several distributions of the collector channels. The 3D computational model, implemented into the open-source software, was reconstructed from an optical coherence tomography. The model has been employed to simulate the aqueous humor dynamics considering buoyancy effects. The presence of the anterior chamber, the trabecular meshwork, and the Schlemm??s canal were taken into consideration with 14 different distributions of collector channels. The influence of collector channels position on the intraocular pressure and shear stress has been analyzed, for a healthy and a glaucomatous condition. Aqueous humor velocity, pressure, temperature, wall shear stress, skin friction coefficient and Nusselt number, are presented for the different cases. The results indicate that the position of the collector channels has a strong influence on the wall shear stress on the Schlemm??s canal and collector channels.
Assessment of the fractional neutron point kinetic equation to simulate core transients with Newtonian temperature feedback
Annals of Nuclear Energy
Marco A. Polo Labarrios 1 , Gilberto Espinosa Paredes 2 , Heriberto Sánchez Mora 3 , J. Ortiz Villafuerte 4
1 Universidad Autónoma Metropolitana, Unidad Cuajimalpa
2 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Instituto Nacional de Investigaciones Nucleares, Departamento de Sistemas Nucleares

Keywords: Reactor dynamics, Fractional neutron point kinetic equations, Anomalous diffusion exponent, Non-local time memory, Newtonian temperature feedback reactivity, Multi term higher-order linear approximation
Abstract: The model of the Fractional Neutron Point Kinetic equations (FNPK) considers a relaxation time for neutrons, as they travel in surrounding media. Relaxation time is associated with a rapid variation in neutron flux, as reflection of fast change of reactivity, and it can be implemented in the differential operator of fractional order related with non-Fick effects, also known as anomalous diffusion exponent and represents non-local time memory. In this work the model of FNPK extended, by adding the temporal term to including the neutron density derivative, is using with the objective of studying the effect of this added term on the behavior of neutron density during a transient, when there exists Newtonian temperature feedback reactivity, using different values of the anomalous diffusion exponent. Although the one-group delayed neutron precursor is use for this analysis, the results of the neutron density behavior were compared with the classical neutron point kinetics equations. The results show that the additional term implemented in this study led to show how the sub-diffusion phenomena have noticeable relevance in the neutron density behavior in those scenarios where the dynamic of a nuclear system is associated to slow transients.
Comparison of thermal performance between green roofs and conventional roofs
Case Studies in Thermal Engineering
Marco A. Polo Labarrios 1 , Sergio Quezada García 2 , Heriberto Sánchez Mora 2 , Azucena Escobedo Izquierdo 2 , Gilberto Espinosa Paredes 3
1 Universidad Autónoma Metropolitana, Unidad Cuajimalpa
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos

Keywords: Green roof, heat transfer, mathematical model, thermal performance, conventional roofs
Abstract: The present study compares the thermal performance of two buildings, one with a conventional roof and another with a green roof. In order to achieve this, a transient mathematical model is developed which considers the heat transfer through the walls and the roof, additionally the model considers the energy balance to determine the change of the temperature inside buildings. The mathematical model needs as input data, solar radiation, ambient temperature and wind speed, which are accessible meteorological variables. The results show that green roofs reduce inside temperature fluctuations of buildings up to 14 K, compared to conventional roofs. Additionally, green roofs allow reaching the comfort temperature: the temperature inside buildings is reduced up to 12 K for warm climates as Mexico City.
Passivity-based control of islanded microgrids with unknown power loads
IMA Journal of Mathematical Control and Information
Sofía Ávila Becerril 1 , Gerardo Espinosa Pérez 1 , Oscar Danilo Montoya Giraldo 2 , Alejandro Garces 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Tecnológica de Bolivar, Laboratorio Inteligente de Energía
3 Universidad Tecnológica de Pereira

Keywords: microgrids, islanded operation mode, passivity-based control, Hamiltonian systems.
Abstract: In this paper, the control problem of microgrids (MGs)operating in islanded mode is approached from a passivity-based control perspective. A control scheme is proposed that, relying only on local measurements for the power converters included in the network representation, achieves both voltage regulation and power balance in the network through the generation of grid-forming and grid-following nodes. From the mathematical perspective, the importance of the contribution lies in the feature that, exploiting a port-controlled Hamiltonian representation of the MG, the closed-loop system??s stability properties are formally proved using arguments from the theory of non-linear dynamical systems. Fundamental for this achievement is the decomposition of the system into subsystems that require a control law and another whose variables can evolve in a free way. From the practical viewpoint, the advantage of the proposed controller lies in the feature that the power demanded by the loads is satisfied without neither computing its specific value nor solving the non-linear algebraic equations given by the power flow, avoiding the computational burden associated with this task. The usefulness of the scheme is illustrated via a numerical simulation that includes practical considerations.
Optimisation of the removal conditions for heavy metals from water: A comparison between steel furnace slag and CeO2 nanoparticles
Arabian Journal of Chemistry
B. M. Mercado Borrayo 1 , Rebeca Contreras 2 , Antoni Sánchez 2 , Xavier Font 2 , Rafael Schouwenaars Franssens 3 , Rosa María Ramírez Zamora 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universitat Autónoma de Barcelona, Escola d'Enginyeria
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electric induction furnace slag, CeO2, Nanoparticles, Waste valorisation, Heavy metals, Water treatment
Abstract: This work studies an innovative approach to water treatment by using recycled electric induction furnace slag for the removal of Cd, Cr and Pb-ions and comparing the results to a treatment with specifically developed CeO2 nanoparticles. The slag was characterised by X-ray Fluorescence, X-ray diffraction and SEM. The effects of initial ion concentration and adsorbent dose were investigated according to an experimental design. Adsorption tests were carried out with ion solutions present in concentrations ranging from 1 to 10?mg/L and adsorbent doses from 0.064 to 0.64?g/L. The removal mechanism for CeO2 is adsorption. For slag, literature proposes a mechanism involving chemical adsorption of Cd2+, Cr6+ and Pb2+ by silanol and aluminol groups; precipitation in the form of metal silicates formed between the cations and silicic acid leached from the slag provides an alternative explanation. The removal efficiencies with nanoparticles are higher than reported for any other adsorbent (including slag) under all test combinations for the three metals investigated. The maximum removal efficiency with slag was 74% for Cr6+, 64% for Cd2+ and 34% for Pb2+, comparable to, or higher than, other materials reported in literature. The treatment with slag has clear promises in terms of economy and scalability.
Output Feedback Hybrid Force/Motion Control for Robotic Manipulators Interacting with Unknown Rigid Surfaces
Alejandro Gutiérrez Giles 1 , Marco Antonio Arteaga Pérez 2
1 University of Naples Federico II, CREATE Consortium and Prisma Laboratory
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Force control, observer design, unknown environment, ultimate boundedness
Abstract: The problem of hybrid force and motion control over unknown rigid surfaces when only joint position measurements are available is considered. To overcome this problem, an extended state high-gain observer is designed to simultaneously estimate the contact force and joint velocities. These estimated signals are in turn employed to design a local estimator of the unknown surface gradient. This gradient is utilized to decompose the task space into two orthogonal subspaces: one for force tracking and the other one for motion control. A simple position Proportional Integral Derivative (PID) and force Proportional Integral (PI) controllers are proposed to track the desired signals. Finally, a mathematical analysis of the closed-loop dynamics is carried out, guaranteeing uniform ultimate boundedness of the position and force tracking errors and of the surface gradient estimation error. A numerical simulation is employed to validate the approach in an ideal scenario, while experiments are carried out to test the proposed strategy when uncertainties and unmodeled dynamics are present.
Stochastic Numerical Simulation of a Turbulent Inverse Diffusion Flame Generated by a CAP-type Burner
Combustion Science and Technology
Luis Cervantes Marcelino 1 , William Vicente 1 , Martín Salinas Vázquez 1 , Eliseo Martínez Espinosa 1 , Rogelio González Oropeza 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Combustion, butane, inverse diffusion flame, numerical simulation, PDF
Abstract: A stochastic model is used to simulate the combustion process in a turbulent inverse diffusion flame (IDF) composed of a laminar diffusive flame and a premixed turbulent flame. In addition, the influence of the turbulence intensity at the outlet of the air injection nozzle was analyzed with this model. The IDF consists of one central air injection and 12 peripheral butane injections. The interaction between the aerodynamics and the thermochemical is implemented by a transport equation for a joint probability density function (PDF). For the chemical kinetic, two different global chemical reaction schemes are used: the first consists of a one-step reaction and the second involves a two-step reaction. The numerical solution of the aerodynamic is found via the finite volume method, and a cell-based Monte??Carlo particle method is used for the transport equation of the joint PDF. The numerical results are compared with experimental data.. The comparison between both global chemical reaction schemes qualitatively represents the thermal structure of the flame. Nevertheless, the two-step reaction demonstrated good accuracy for the temperature distribution of the flame, so the two-step reaction was used to analyze the behavior of the flame. The results show the increase of turbulence intensity does not modify the thermal structure of the IDF, but the dimension and temperature distribution of the flame present significant changes with an increase in the turbulence intensity.
Reply to Molina-Garza et al. (2019) 'Discussion of: Ortega-Flores et al. (2018) provenance analysis of Oligocene sandstone from the Cerro Pelón area, southern Gulf of Mexico'
International Geology Review
Berlaine Ortega Flores 1 , Michelangelo Martini 1 , Sandra Guerrero Moreno 2 , Vanessa Colás 1 , Luigi Solari 3 , Elena Centeno García 1 , Gilberto Silva Romo 4 , Manuel Grajales Nishimura 1
1 Universidad Nacional Autónoma de México, Instituto de Geología
2 Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Tierra
3 Universidad Nacional Autónoma de México, Centro de Geociencias
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Oligocene turbidites, provenance, southern Gulf of Mexico, Nanchital Conglomerate
Abstract: The origin of the Oligocene turbidites from the Cerro Pelón area in south Gulf Mexico proposed by Ortega-Flores et al. (2018) is in disagree with the interpretations made by Molina-Garza et al. (2019), which main criticism is based on U-Pb ages of detrital zircons from the matrix of a conglomerate unit, which they refer to as ??Nanchital Conglomerate??, as well as on the presence of limestone, gabbros, and mafic protolith-derived clasts. Molina-Garza et al. (2019) basically interpret the Nanchital Conglomerate as Miocene in age, which was sourced mainly from metamorphic complexes including their sedimentary covers located to the west and south of the Cerro Pelón area. For some reason, Molina-Garza et al. (2019) suppose that the Nanchital Conglomerate should have the same provenance sources that the Oligocene turbidites from Cerro Pelón area, reported by Ortega-Flores et al. (2018). Based on the foregoing, we strongly disagree with Molina-Garza et al. (2019) considering that, from the beginning, they intend to compare two units of different age. Additionally, the scarce data reported from both the matrix and the clasts of the Nanchital Conglomerate are not determinant for interpreting the provenance of this conglomeratic unit and subsequently, to consider the same rock sources from the Oligocene through Miocene time.
Reactive Power Compensation in Distribution Systems Through the DSTATCOM Integration Based on the Bond Graph Domain
Arabian Journal for Science and Engineering
Roberto Tapia Sánchez 1 , J. Aurelio Medina Ríos 1 , Nadia María Salgado Herrera 2 , David Granados Lieberman 3 , Juan Ramón Rodríguez Rodríguez 4 , Jose Luis Guillén Aguirre 1
1 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Instituto de Energías Renovables
3 Instituto Tecnológico Superior de Irapuato, Posgrado de Ingeniería Eléctrica
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bond graph, DSTATCOM, Reactive power compensation, Opal-RT Technologies, Distribution system
Abstract: In this paper, the distribution static compensator model based on the bond graph (BG) domain is presented. The methodology is applied to reactive power compensation in distribution systems where a traditional phase lock loop for sensing the AC grid frequency is not needed. The control law is developed using the inverse BG model, which is extracted using the bi-causality concept. In this way, it is possible to perform the distribution system analysis completely in the BG domain. This means that the graphical model is inverted by obtaining the open-loop control law structure, and then the close loop is formulated. The balanced and unbalance conditions are analyzed, generating a control structure that is robust and efficient. The efficacy of the proposed methodology is shown through: partial and complete system simulations in MATLAB/Simulink® (MATLAB r2015b, Natick, Massachusetts, 01760, USA), as well as experimental laboratory tests. Such tests use: the rapid control prototyping concept and the real-time simulator Opal-RT Technologies® (Montreal, QC, Canada).
Modelling of PV Systems as Distributed Energy Resources for Steady-state Power Flow Studies
International Journal of Electrical Power & Energy Systems
Luis Miguel Castro González 1 , Juan Ramón Rodríguez Rodríguez 1 , Cecilia Martín del Campo 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Distributed energy resources, Photovoltaic systems, Power flow analysis
Abstract: This paper introduces a PV system model useful for steady-state power flow studies of practical electrical networks. This multi-array PV system model features a comprehensive representation of the three main stages taking part in solar energy conversion systems: (i) PV arrays for the solar-to-electrical energy conversion, (ii) the DC boost converter useful for establishing the MPPT strategy and for stepping up the output voltage of the PV arrays, and (iii) the DC-to-AC power conversion by the voltage source converter (VSC) used to link the PV system with the AC grid. The derived PV system model is flexible and modular as it permits to consider any desired number of PV arrays with different irradiance conditions each. For validation purposes, a 1.5-MW PV system coupled to a 3-bus AC network was simulated. Its steady-state power flow results were compared against those obtained by a highly-detailed switching-based PV model implemented in Simulink©. It is shown that the proposed model retains sufficient accuracy since the computed relative errors were inferior to 2% between both fundamentally different methods. The IEEE 57-bus test grid is also used to incorporate five PV plants, thus showing the practicality of the introduced modeling approach for distributed PV systems.
Time-space fractional neutron point kinetics: Theory and simulations
Annals of Nuclear Energy
Erick Gilberto Espinosa Martínez 1 , Juan Luis François Lacouture 1 , Cecilia Martín del Campo 1 , Nader Maleki Moghaddam 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Amirkabir University of Technology, Energy Engineering and Physics Department

Keywords: Fractional calculus, Neutron point kinetics, Time hereditary effects, Space memory effects, Anomalous diffusion, Temperature feedback effects
Abstract: In this work the mathematical derivation and numerical analysis of a fractional nuclear reactor point kinetics in time and space (TSFNPK) is presented. The TSFNPK model was derived considering a non-Fickian law for the neutron density current where the differential operators in space and time are of fractional order. The TSFNPK equations presented in this work constitutes a novel model for nuclear reactor kinetics, thus represent an extended model with respect to other fractional models and the classical neutron point kinetics equations. The model considers two diffusion exponents: one for the differential operator dependent in time and another for the dependent operator in space. Both exponents effect is numerically analyzed considering changes of reactivity step type, and temperature feedback reactivity. A first approach of the TSFNPK is presented, without temperature effects, and then a second approach considering temperature feedback effects is analyzed. In a following work, as a demonstration of application, a detailed analysis along with verification will be presented.
Linear instability analysis of the onset of thermal convection in an Ekman-Couette-flow
International Journal of Heat and Mass Transfer
Rubén Ávila Rodríguez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Tau-Chebyshev, Shear flow, Ekman layer, Thermal convection, Spectral method, Inertial instabilities
Abstract: The onset of thermal convection in a plane layer with rotation and shear is investigated. The boundaries of the layer are parallel to the plane of the Cartesian coordinate system. The layer rotates at a constant angular velocity ωz around the z axis, and is sheared by moving, along the x direction, the lower and upper boundaries parallel to themselves with constant velocity and Uw respectively. The temperature of the lower boundary is higher than the temperature of the upper boundary. The linear instability equations are solved by using the Tau-Chebyshev spectral numerical method. The critical parameters of the stationary, transverse and longitudinal convective rolls are presented. The relationship between the critical Rayleigh number and: (i) the Taylor number, (ii) the wavenumber vector, (iii) the Reynolds number, (iv) the kinetic energy norm and (v) the heat transfer at the sliding plates, is presented. We find the combination of the critical parameters that lead to the occurrence of two interesting situations, these are (a) a high value of the kinetic energy norm which promotes the formation of inertial longitudinal rolls, which are considered as hydrodynamic instabilities modified by the buoyancy force, and (b) a small value of the kinetic energy norm together with a high value of the heat transfer at the sliding plates. The latter situation, may be considered in the single-crystal growth from the melt processes.
Coupled Monte Carlo-burnup and CFD analysis of coated UN and UC fuels in an HPLWR fuel assembly
Progress in Nuclear Energy
Landy Castro 1 , Juan Luis François Lacouture 1 , Carlos F. García Hernández 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de La Habana, Instituto Superior de Tecnologías y Ciencias Aplicadas

Keywords: SCWR, HPLWR, Coupled calculation, Burnup, Coated ceramic fuels
Abstract: Ceramic nuclear fuels may have potential benefits to be considered as nuclear fuels in future Supercritical Water Reactors (SCWR), they offer the advantage of high thermal conductivity and high-density values compared to uranium dioxide. In recent years, uranium nitride (UN) and uranium carbide (UC) are being considered as viable options for alternative nuclear fuels in SCWR, but an important issue is related to their chemical reactivity with water and nickel, which forces the use of coatings for fuel pellets, reducing heavy metal volume and reducing their thermal and neutronic performance. The main purpose of the study is the analysis of the burnup dependent performance of coated ceramic fuels in the SCWR compared with conventional UO2 fuel. Particularly, it focuses on the study of the fuel centerline temperature and the cladding surface temperature. Furthermore, the evolution of the neutron multiplication factor, the fissile inventory ratios and the main heavy isotopes composition along burnup are analyzed and compared to asses proliferation resistance issues. The use of UN fuel coated with Zirconium Carbide (ZrC) and UC fuel coated with Titanium Nitride (TiN) in the fuel assembly of the High-Performance Light Water Reactor is analyzed, and the results are compared with those of the conventional UO2 fuel. The comparative study was conducted for a hypothetic operation time of 540 days. Due to the large coolant density variation along with the active height of the fuel assembly, coupled calculations are performed using the Monte Carlo MCNP6 code and the CFD code ANSYS-CFX 19, taking into account the capabilities of CFD codes to describe the heat transfer mechanisms at supercritical conditions. The main results show significantly lower values of the centerline temperature distribution in UN_ZrC and UC_TiN fuels compared to UO2 fuel. The fuel burnup values obtained at the end of the 540 days are practically the same, a slightly higher burnup is obtained for UC_TiN fuel because of its lower amount of heavy metals in the initial composition. The evolution of the fissile inventory is practically the same for all the analyzed fuel options, around 65% of fissile inventory is still present in the core at EoC. Total plutonium production shows a decrease of 1.85% (UN??ZrC) and 4.53% (UC??TiN) with respect to UO2 fuel. Coated ceramic fuels show a slightly improved proliferation resistance compared with UO2 fuel, since a slightly smaller fraction of 239Pu is obtained in their compositions.
Wind Risk Assessment of Electric Power Lines due to Hurricane Hazard
Natural Hazards Review
Eduardo Reinoso 1 , Mauro Niño Lázaro 2 , Emilio Berny 1 , Indira Inzunza 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electric power, Power transmission towers, Wind loads, Wind speed, Wind power, Cables, Mexico
Abstract: This paper proposes a methodology to assess the wind risk of electrical transmission towers considering the coupling of the tower with the cables and a failure mechanism based on capacity. In the proposed methodology, the necessary steps to assess risk (hazard, exposure, vulnerability) and their geographic representation are presented. Wind hazard is briefly described considering hurricane events as the basis for the analysis of wind speed. The components of a transmission line are presented, and the forces acting over it are evaluated according to given specifications. The structural vulnerability of the tower is computed based on the damage levels that depend on the failure mechanism presented with different wind speeds incidences (0°, 45°, and 90°); these results are used to define the damage probability distribution. Finally, a case study of the expected losses computed with a probabilistic risk analysis for the transmission towers in Mexico is presented along with a more detailed analysis of the transmission towers between the Mérida and Lerma substations, reflecting the importance of the geographic location in the risk assessment.
New phasorial oriented single-Pi loop control for industrial vsc-pfc rectifiers operating under unbalanced conditions
IET Power Electronics
Mario A. Santoyo Anaya 1 , Nadia María Salgado Herrera 2 , Juan Ramón Rodríguez Rodríguez 3 , Luis Miguel Castro González 3 , Edgar Lenimirko Moreno Goytia 1 , Vicente Venegas Rebollar 1
1 Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación
2 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: AC-DC power convertors, harmonic distortion, machine control, PI control, power factor, power factor correction, power grids, power supply quality, PWM rectifiers, rectifiers, rectifying circuits, switching convertors, voltage control
Abstract: Due to several reasons, the three-phase voltages of power grids cannot be balanced. The performance of AC??DC converters using dq0-based controls can be severely affected by the presence of unbalanced input AC voltages. Different to these proposals, this study presents a new easy-to-implement control scheme based on a single PI loop algorithm for VSC-PFC rectifiers using a phasorial approach. This new scheme has various significant advantages: (i) fast counteracting of large unbalanced voltage and current conditions; (ii) power factor??=??1 at any unbalanced sag operating conditions; (iii) negligible current harmonic distortion and (iv) low-ripple DC voltage. All these features are concurrently obtained. The proposed single-PI loop VSC-PFC rectifier control strategy is theoretically and experimentally validated. A revision of the main results and characteristics of various proposed techniques that are similar to the one proposed in this study is also carried out, qualitatively indicating the main advantages featured by the proposed control strategy for VSC-PFC rectifiers.
Two alternative approaches to the solution of cyclic chains in transmutation and decay problems
Computer Physics Communications
Carlos Antonio Cruz López 1 , Juan Luis François Lacouture 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bateman??s Equation, Cyclic chains, Linear chain method, Transmutation and decay networks, Forward method, Backward method, Burnup methodology, Repeated constants
Abstract: In several burnup and activation problems there is a recurrent issue related to the singularities in the Bateman??s solution due to its inability to solve linear transmutation schemes where there are repeated isotopes, or where there are two different isotopes with the same removal coefficients. Most of these types of transmutation schemes are called cyclic chains. In these cases, the Bateman??s solution fails due to the presence of subtractions between the mentioned coefficients in some denominators, which eventually become zero and undefined. In order to overcome this problem, two methodologies have been reported in the open literature. The first one consists in introducing small modifications in the repeated removal coefficients, preventing the presence of zeros in certain denominators. The second is to develop more general equations for the Bateman??s solution. Nevertheless, both methodologies are based on the approximation of the cyclic chains with the linear chain method, whose error has not been studied until now. The study of this error is fundamental to omit cyclic chains and to reduce the execution time of the algorithm. In the present work, a more general approach to the cyclic chains was studied, starting with the description and classification of the transmutation and decay networks that generate them. Afterward, two different approaches to solve some of these structures were proposed, which are not based on the linear chain method. One of them is based on a power series analysis, and the other one is related to a numerical analysis of the roots of a polynomial in the Laplace transform space. Additionally, computer algorithms were developed for each approach to facilitate their implementation in a burnup or activation code, and a numerical comparison with the linear chain approximation was carried out. Through the present work, it was possible to compute the actual error involved when the linear chain is used for approximating cyclic chains, and to conclude if a cyclic chain can be ignored in a burnup problem.
Evaluation and correlation of electrochemical and mechanical properties of PVA/SA nanofibres
Surface and Interface Analysis
Alba Covelo Villar 1 , Sandra Rodil 2 , Edgar Oliver López Villegas 3 , Carlos Andrés Álvarez 4 , 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
3 Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas
4 Universidad Nacional Autónoma de México, Facultad de Odontología

Keywords: characterization, electrochemical impedance, spectroscopy (EIS), electrospinning, nanofibre, sodium alginate
Abstract: The present study evaluates and correlates the morphology of poly (vinyl alcohol) (PVA) and sodium alginate (SA) nanofibres with their internal structure to determine dielectric and tensile properties for future applications as long?lasting and resistant cell scaffolds. This work generates electrospun nanofibres mixing SA concentration in a PVA solution cross?linked in calcium chloride media. The dielectric properties of the nanofibres that were obtained using electrochemical impedance spectroscopy (EIS) show that at higher amount of SA in the PVA/SA fibres, the cross?linking process occurs at shorter times, indicating the modification of the internal structure of the PVA/SA. The X?ray photoelectron spectra (XPS) demonstrate that the chemical composition of the nanofibres varies depending on the depth profile. The transmission electron microscopy (TEM) proves that the PVA/SA is formed as a core?shell coaxial nanofibre. The tensile testing demonstrates that with a higher SA concentration, the mechanical properties show brittleness.
Global sliding mode observers for some uncertain mechanical systems
IEEE Transactions on Automatic Control
W. Alejandro Apaza Pérez 1 , 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: Observers, Mechanical systems, Friction, Uncertainty, Convergence, Perturbation methods, Position measurement
Abstract: This paper proposes a global sliding mode observer for a class of nonlinear mechanical systems with two degrees of freedom. For the observer design, besides the usual Coriolis and centrifugal forces, we consider (discontinuous) dry and viscous friction and non vanishing uncertainties/perturbations. Moreover, the system is not required to be bounded-input-bounded-state, rendering the observer design problem challenging. For this class of systems, a dissipativity-based sliding-mode observer, with theoretically exact global finite-time convergence to the actual velocities, is proposed. To illustrate the effectiveness of the proposed observer, experimental results on a cart-pendulum system are presented.
Light electric vehicle powertrain: Modeling, simulation, and experimentation for engineering students using PSIM
Computer Applications in Engineering Education
Salvador Vidal Bravo 1 , Javier De la Cruz Soto 2 , Mario Roberto Arrieta Paternina 1 , Mónica Borunda 2 , Alejandro Zamora Mendez 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Nacional de Electricidad y Energias Limpias, Gerencia de Control, Electrónica y Comunicaciones
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica

Keywords: engineering students, light electric vehicle, powertrain, PSIM
Abstract: Electric transport has been gaining more interest and importance in the last years. Moreover, the variety of transport systems driven by an electric motor has also been increased. Therefore, it is very important to provide engineering students with solid and comprehensible knowledge, as well as handly tools, for modeling an electric traction system. So far, this has been a difficult task for undergraduate students due to a variety of subjects involved, such as electric machines, power converters, control systems, and load estimations. This work is intended to provide a detailed and comprehensible description of the analysis, modeling, and implementation of a powertrain of a light utility vehicle using power electronics simulation (PSIM) commercial software in order that the student acquires the required knowledge for analyzing multiple configurations in the powertrain.
Identification of Electronic Components Susceptible to Deterioration by Atmospheric Corrosion
Journal of Electronic Materials
Francisco Sánchez Pérez 1 , Armando Ortiz Prado 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Electronic components, atmospheric corrosion, accelerated tests, gases pollutants
Abstract: Electronic components are often susceptible to deterioration by environmental effects. Several studies have been reported on atmospheric corrosion of electronic devices with focus on functionality, storage capacity, and their miniaturization. However, there is a lack of studies focused on identifying the components most susceptible to atmospheric corrosion, the corrosion products generated in them, and the possible variables that have a greater impact on deterioration. The present study is focused on linking the deterioration of electronic boards with temperature and humidity cycles. This was accomplished through accelerated tests inside an atmospheric chamber, where the concentrations of pollutant gases (NO2 and SO2) are kept constant. Each trapezoidal cycle within the accelerated tests equals one day of field exposure. The results show that the NO2 and SO2 gasses reduced the life of the electronic components by 49.8%. The SO2 gas was found to be the contaminant gas that most influenced the deterioration of electronic devices. Energy-dispersive spectroscopy (EDS) show the formation of CuSO4. The development of protective coating against these pollutant gasses could improve the operation of electronic components.
Snake Aerial Manipulators: A Review
IEEE Access
Julio Mendoza Mendoza 1 , Víctor J. González Villela 1 , Carlos Aguilar Ibañez 2 , Miguel Santiago Suárez Castañón 3 , Leonardo Fonseca Ruiz 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Centro de Investigación en Cómputo
3 Instituto Politécnico Nacional, Escuela Superior de Cómputo
4 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas

Keywords: Aerial manipulator, cooperative systems, UAS
Abstract: In this document, a review about snake aerial manipulators is presented. The most common mechatronical implications found in their design are described. The text is presented to the reader as a set of modules, this include topics about structural dynamics, aerodynamics, power and energy, propulsion, thrust-vectoring and level of autonomy of aircrafts, also highlights about use of sensors, control methods and flight schemes.
Feasibility Study for Using Energy-Harvesting Floor in Urban Public Transportation System: Case of Subway Stations
Journal of Electrical Power & Energy Systems
Miguel A. Saldaña Cabrera 1 , Aida Huerta Barrientos 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Energy-harvesting floor, Subway stations, Mexico City, Feasibility study
Abstract: Over the past 50 years, human activity has released huge amounts of green-house gases, particularly because of their dependence on fossil fuels, causing global warming which in turn brings variations in the weather for long periods leading to climate change. In this direction, the adoption of renewable energy and the increase in the electric car fleet are presented as the promising solution of a more efficient and sustainable paradigm. The principal purpose of this paper is to develop a feasibility study for using energy-harvesting floor in urban public transportation system and to apply it to the case of Mexico City subway stations. First, we review the literature about the use of renewable energy in urban public transport system around the world as well as the best practices and the feasibility studies. Second, we propose a feasibility study for using energy-harvesting floor in urban public transport system. Third, we validate the feasibility study considering the case of a Mexico City subway station. Even though the adoption of technology based on renewable energy in Mexico is low due to the high investment required, the results of this study showed the benefits of using energy-harvesting floor in Mexico City subway stations. Such solution contributes mainly at the mitigation of CO2 level and the installation is ideal in urban context. We consider that the feasibility study proposed can support the decision-making process of Mexico City subway authorities.
On adaptive sliding mode control without a priori bounded uncertainty
Spandan Roy 1 , Simone Baldi 2 , Leonid Fridman Golredich 3
1 International Institute of Information Technology Hyderabad, Robotics Research Center
2 Technische Universiteit Delft, Delft Center for Systems and Control
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Adaptiva sliding mode, Euler - Lagrange systems, switching gain, uncertainty
Abstract: Adaptive Sliding Mode Control (ASMC) aims to adapt the switching gain in such a way to cope with possibly unknown uncertainty. In state-of-the-art ASMC methods, a priori boundedness of the uncertainty is crucial to ensure boundedness for the switching gain and uniformly ultimately boundedness. A priori bounded uncertainty might impose a priori bounds on the system state before obtaining closed-loop stability. A design removing this assumption is still missing in literature. A positive answer to this quest is given by this note where a novel ASMC methodology is proposed which does not require a priori bounded uncertainty. An illustrative example is presented to highlight the main features of the approach, after which a general class of Euler??Lagrange systems is taken as a case study to show the applicability of the proposed design.
Physicochemical and Sensory Analysis of Commercial Honeys of Apis Mellifera Produced by Cooperative Societies in Mexico City
International Journal of Food Science and Agriculture
Aida Huerta Barrientos 1 , Laura P. Ávila Callejas 1 , Alma E. Vera Morales 1 , Miguel A. Saldaña Cabrera 1 , Eduardo García López 1 , Emiliano Gutiérrez Ayala 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Physicochemical Analysis, Honey, Mexico City, Urban Apiculture
Abstract: In Mexico, there are different organization and associative figures that group beekeepers nationally as well as locally. An specific kind of social organization for Mexican Beekeepers is the cooperative society figure, which is formed by persons based on common interests and on the principles of solidarity, self-effort and mutual aid, with the purpose of satisfying individual and collective needs, through the performance of economic activities of production, distribution and consumption of goods and services related with beekeeping. In Mexico City, there are three cooperative societies specialized in beekeeping, however, limited information about the quality of commercial honeys of Apis Mellifera that is produced and marketed by such cooperative is limited or does not exist. Therefore, the purpose of this study is to contribute to the knowledge of the quality of commercial honeys of Apis Mellifera that is produced and marketed by cooperative societies in Mexico City, through a sensory and a physicochemical analysis. The color, water content, electrical conductivity, pH, total acidity, free acidity, lactone, and reducing sugars profile as well as the sensory characteristics were analyzed. All tested honey samples were within the Official Mexican Standard and the Codex Alimentations, 2001 limit, except cooperative society 2 honey and cooperative society 3 honey in water content value and cooperative society 1 honey in lactone value. This study concludes that the commercial honey of Apis Mellifera produced and marketed by the three cooperative societies in Mexico City had a good level of quality.
Forward Link Optimization for the Design of VHTS Satellite Networks
Flor G. Ortiz Gómez 1 , Ramón Martínez 1 , Miguel A. Salas Natera 1 , Andrés Cornejo 2 , Salvador Landeros Ayala 2
1 Universidad Politécnica de Madrid, Information Processing and Telecommunications Center
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: CCM, CINR, cost per Gbps in orbit, multibeam satellite communications, system optimization, VCM, VHTS
Abstract: The concept of geostationary VHTS (Very High Throughput Satellites) is based on multibeam coverage with intensive frequency and polarization reuse, in addition to the use of larger bandwidths in the feeder links, in order to provide high capacity satellite links at a reduced cost per Gbps in orbit. The dimensioning and design of satellite networks based on VHTS imposes the analysis of multiple trade-offs to achieve an optimal solution in terms of cost, capacity, and the figure of merit of the user terminal. In this paper, we propose a new method for sizing VHTS satellite networks based on an analytical expression of the forward link CINR (Carrier-to-Interference-plus-Noise Ratio) that is used to evaluate the trade-off of different combinations of system parameters. The proposed method considers both technical and commercial requirements as inputs, including the constraints to achieve the optimum solution in terms of the user G/T, the number of beams, and the system cost. The cost model includes both satellite and ground segments. Exemplary results are presented with feeder links using Q/V bands, DVB-S2X and transmission methods based on CCM and VCM (Constant and Variable Coding and Modulation, respectively) in two scenarios with different service areas.
Green roof heat and mass transfer mathematical models: A review
Building and Environment
Sergio Quezada García 1 , Gilberto Espinosa Paredes 2 , Marco A. Polo Labarrios 3 , Erick Gilberto Espinosa Martínez 1 , Azucena Escobedo Izquierdo 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
3 Universidad Autónoma Metropolitana, Unidad Cuajimalpa

Keywords: Green roof, Heat transfer, Mass transfer, Mathematical model, Benefits, Validation
Abstract: This work reviews and criticisms the most important mathematical models for heat and mass transfer in green roofs developed and published during the last three decades. The review let see the evolution of the mathematical modeling in green goof, it start with an analysis of the first attempts to model the heat and mass transfer and proceeds to the most representative current models. The criticism shows the most important considerations of each model and the heat flux calculation, as well as the most important contributions of each author in green roof modeling. Currently, there are many mathematical models in green goof but each one of them has their own notation, it complicates the study of this field. An additionally, contribution of this work is the homogenize of the notation used by the different authors, and the presentation of the different methods developed to calculate the heat flux terms. This work serves as a starting point for the proposal of new heat and mass transfer mathematical models; as well as to give to researchers an overview of the phenomena that have been considered in the transfer of heat and mass through green roofs, and help to understand the process to development models more accurate. Finally, some recommendations about the direction that modeling work in this field must be followed are proposed.
Discrete-Time Implementation of Homogeneous Differentiators
IEEE Transactions on Automatic Control
Stefan Koch 1 , Markus Reichhartinger 1 , Martin Horn 2 , Leonid Fridman Golredich 3
1 Graz University of Technology, Institute of Automation and Control
2 Graz University of Techonology, Institute of Automation and Control
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Estimation, robust exact differentiator, sampled data control, sliding-mode control
Abstract: The discrete-time version of Levant's arbitrary order robust exact differentiator, which is a forward Euler discretized version of the continuous-time algorithm enhanced by linear higher order terms, is extended by taking into account also nonlinear higher order terms. The resulting differentiator preserves the asymptotic accuracies with respect to sampling and noise known from the continuous-time algorithm. It is demonstrated in a simulation example and by differentiating a measured signal that the nonlinear higher order terms allow reducing the high-frequency switching amplitude whenever the (n+1)th derivative of the signal to be differentiated vanishes, leading to an improvement in the precision.
An efficient method for Contingency-Constrained Transmission Expansion Planning
Electric Power Systems Research
Guillermo Gutiérrez Alcaraz 1 , Néstor González Cabrera 2 , Estaban Gil 3
1 Instituto Tecnológico de Morelia, Departamento de Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Técnica Federico Santa María, Departamento de Ingeniería Eléctrica

Keywords: Optimization, Transmission Expansion Planning, Mixed-integer linear programming, Power system security, Risk management
Abstract: This paper proposes an efficient method based on a mixed-integer linear programming (MILP) model to solve the multistage Contingency-Constrained Transmission Expansion Planning (CCTEP) problem. To account for security, an iterative algorithm based on Line Outage Distribution Factors (LODF) screens the worst-case contingency (either in existing or candidate lines) and dynamically adds constraints to the Transmission Expansion Planning (TEP) formulation to enforce the security criterion, reducing both the number of decision variables and simulation times with respect to alternative approaches. Transmission losses are included through the use of piecewise linear expressions. Furthermore, operational flexibility of generation resources is considered through the use of representative daily load curves (RDLC) to allow modeling of generator ramping constraints. The method is initially illustrated and validated through numerical simulations of the classic Garver??s system. Then, the IEEE 118-bus and 300-bus systems are used to test its performance. The proposed approach can avoid under-investment in network capacity caused by neglecting transmission losses, security, and flexibility constraints.
Model-based synchrophasor estimation by exploiting the eigensystem realization approach
Electric Power Systems Research
Alejandro Zamora Méndez 1 , Francisco Zelaya 2 , José Antonio de la O Serna 3 , Joe H. Chow 4 , Mario Roberto Arrieta Paternina 2
1 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
4 Rensselaer Polytechnic Institute, Department of Electrical Computer and Systems Engineering

Keywords: Phasor estimation algorithm, Frequency estimates, Phasor measurement unit, Eigensystem realization, Synchrophasors
Abstract: This paper proposes an eigensystem realization (ER) approach to accurately provide synchrophasor estimates. The proposal improves the frequency computation and its tracking since the ER-based estimator works as a frequency adaptive method, reducing the total vector error (TVE) in the presence of dynamic compliances reported in the IEEE Synchrophasor Std. C37.118. Phasor estimates such as amplitude, phase, frequency and the rate of change of amplitude (ROCOA) can be provided in one-cycle. The new ER-based phasor estimator is evaluated under steady-state, dynamic and noisy conditions using both theoretical and actual signals stemming from a commercial PMU and a Digital Fault Recorder (DFR). Comparisons are established with the well known Discrete Fourier Transform (DFT), Prony method and the Interpolated DFT (IpDFT). Finally, the results exhibit that the proposed approach attains reliable estimates, even though under polluted conditions by high harmonic content, being able to track the changes in amplitude, phase, frequency, with enough precision. Thus, the eigensystem realization-based method becomes a class P phasor measurement algorithm.
Active frequency selective surface with tunable and switchable properties based on loaded split ring slots
Electronics Letters
T. E. Esparza Aguilar 1 , Jorge Rodríguez Cuevas 1 , Alexander Martynyuk 1 , José Ismael Martínez López 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: waveguides, resonators, frequency selective surfaces, varactors, p-i-n diodes
Abstract: An active frequency selective surface (AFSS) with reconfigurable tunable and switchable properties is studied in this Letter. The AFSS unit cell consists of a split ring slot resonator loaded with a varactor diode. The proper biasing of the varactor diode enables diverse functional modes. The proposed AFSS with a single control device in each unit cell demonstrates transmitting and reflecting properties in two operating bands. Additionally, in one of the bands, the tuning of the resonant frequency is achieved in a transmission window. A unit cell active diaphragm at X-band has been designed and fabricated to characterise the AFSS based on the waveguide simulator. The measured results, using the waveguide simulator approach, show either a transmitting tunable or reflecting response in the lower band with resonant frequencies from 9.002 to 9.354 GHz and a transmitting or reflecting response in the upper band at the centre frequency of 11.87 GHz.
Enhancement of dynamic phasor estimation-based fault location algorithms for AC transmission lines
IET Generation, Transmission and Distribution
Daniel Guillen 1 , Christian Salas 2 , Luis Fernando Sánchez Gómez 2 , Luis Miguel Castro González 2
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: fault diagnosis, fault location, Kalman filters, power transmission faults, power transmission lines, power transmission protection
Abstract: A new technique to improve fault location methods in AC transmission lines is introduced in this study. The identification of fault location is carried out using one-end fault location algorithms based on impedance through dynamic phasors. This timely approach relies upon the fact that a fault resistance may introduce errors in the distance estimation when a fault takes place. Therefore, active power variations caused by the fault are used to enhance the fault location algorithms, i.e. power losses increase during the fault period for non-zero fault resistances. The present approach is extensively evaluated, using ATP-EMPT software, which relies upon the computation of a compensation factor associated with the rate of change in the resistance during pre-fault and fault conditions. This is achieved through the estimated phasors for voltage and current. Furthermore, the dynamic phasor estimation technique Taylor-Kalman-Fourier Filter is compared against a static phasor method. The proposed approach is validated using three fault location algorithms which are evaluated under different fault conditions, such as fault inception, location, and fault resistance. Results show that this proposed technique improves the fault location including fault resistances by 3% with respect to existing approaches.
Modelling of high impedance faults in distribution systems and validation based on multiresolution techniques
Computers and Electrical Engineering
Vicente Torres García 1 , Daniel Guillen 2 , Jimena Olveres 3 , Boris Escalante Ramírez 1 , Juan Ramón Rodríguez Rodríguez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico y de Estudios Superiores de Monterrey, Escuela de Ingenería y Ciencias
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas

Keywords: Detection, Fault current, Feature selection, High impedance fault, Hermite transform, Multiresolution, Wavelet transform
Abstract: The electric arc phenomenon associated with high impedance faults (HIFs) in distribution systems is an exciting subject that directly impacts over the reliability of electrical utilities, because fault currents are very small and present non-linearity and asymmetrical waveforms. Therefore, HIFs may be an undetectable phenomenon by overcurrent protections like fuses, re-closers, and relays. A HIF entails a challenge for its detection and location. In this sense, more realistic high impedance models, as well as reliable signal processing techniques, are needed to extract all transient characteristics aiming to detect HIFs in distribution networks. In this work, an efficient Resistive-HIF model is proposed and implemented into the Alternative Transients Program of the Electromagnetic Transients Program (ATP/EMTP) software to represent the main characteristics of HIFs. The model is compared against well-prove models by using two multiresolution approaches based on the Hermite transform and the Wavelet transform considering different frequency bands.
Mass transfer through a concentric-annulus microchannel driven by an oscillatory electroosmotic flow of a Maxwell fluid
Journal of Non-Newtonian Fluid Mechanics
M. Peralta 1 , José Carlos Arcos Hernández 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Oscillatory electroosmotic flow, Maxwell fluid, annular microchannel, mass transfer, species separation
Abstract: In this work we develop a theoretical analysis for the mass transfer of an electroneutral solute in a concentric-annulus microchannel driven by an oscillatory electroosmotic flow (OEOF) of a fluid whose behavior follows the Maxwell model. The annular microchannel connects two reservoirs that have different concentrations of the solute. For the mathematical modeling of the OEOF, we assume the Debye-Hückel approximation and that the wall zeta potentials of the micro-annulus can be symmetric or asymmetric. The governing equations are nondimensionalized, from which the following dimensionless parameters appear: an angular Reynolds number, the ratio of the wall zeta potentials of the annular microchannel, the electrokinetic parameter, the dimensionless gap between the two cylinders, the Schmidt number and the elasticity number. The results indicate that the velocity and concentration distributions across the annular microchannel become non-uniform as the angular Reynolds number increases, and depend notably on the elasticity number. It is also revealed that with a suitable combination of values of the elasticity number and gap between the two cylinders, together with the angular Reynolds number, the total mass transport rate can be increased and the species separation can be controlled.
Theoretical evaluation of dilution processes versus thermal effects induced on the transport of heavy oil
Journal of Petroleum Science and Engineering
G. Silva Oliver 1 , Edgar Ramírez Jiménez 1 , José Felipe Sánchez Minero 1 , H. Valdés Pastrana 1 , Federico Méndez Lavielle 2 , Gabriel Ascanio 3 , Juan Pablo Aguayo Vallejo 3 , Salvador Sánchez 3
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Química e Industrias Extractivas
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología

Keywords: Fluid composition, dilution mechanism, dynamic viscosity, environmental temperature, thermal effects, maya heavy oil
Abstract: In the present work, the dilution mechanism is investigated as an option to avoid considerable flow reductions in the non-isothermal transport of heavy oils (high-viscous fluids). In this case, we assume that environmental conditions can imply appreciable thermal effects in such flows; thus, to perform an appropriate analysis, the governing equations must be modeled considering the behavior of the dynamic viscosity as a function of the temperature and composition of the fluid. To evaluate the above, the non-isothermal transport of a heavy oil along buried pipelines is analyzed, it represents a good engineering example, given that, millions of crude oil barrels are transported daily using pipeline networks. In these systems, heat transfer processes and the flow hydrodynamics work in a coupled manner due to the thermal dependence of the fluid viscosity; in addition, the present formulation is extended to include the influence of the fluid composition as a part of the study. In summary, the main results in this work allow estimating how the dilution mechanism can mitigate all thermal effects induced by the environment, which are responsible for the changes in the volumetric flow rate when the non-isothermal condition is considered. Moreover, the theoretical formulation reveals that this type of engineering application represents a version of the Graetz??Nusselt problem; where, for values of Gz/?u<1, the thermal effects dominate the flow hydrodynamics and the dilution mechanism is inefficient, obtaining a relatively small improvement in the volumetric flow rate. Conversely, for values of Gz/?u>1, the dilution mechanism controls the flow hydrodynamics, resulting in an exponential increment in the volumetric flow rate. Clearly, for the case of Gz/?u~1, both the dilution mechanism and thermal effects dispute the control of the flow hydrodynamics. Thus, we can infer that by using together an adequate thermal insulation and a good handling of the dilution mechanism, heavy oils can be transported through conventional pipelines even under unfavorable environmental conditions.
Dynamic phasor-driven digital distance relays protection
Electric Power Systems Research
Ernesto Vázquez 1 , Alejandro Zamora Méndez 2 , Mario Roberto Arrieta Paternina 3 , Luis A. Trujillo Guajardo 1 , José Antonio De la O Serna 4
1 Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica
2 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica

Keywords: Distance relay, phase comparator, phasor estimation, digital filters, Taylor-Kalman-Fourier, phasor measurement unit
Abstract: This paper describes an in-depth signal processing analysis of the second-order Taylor-Kalman-Fourier (T2KF) filter as input signal to a phase comparator in digital distance relay. Tripping condition corresponds a successful phase comparison between operating signal and polarization signal (the angle among signals is inside angular limits, typically ± 90??), this is equivalent to the fact that the measured impedance is less than the relay setting. The analysis is performed by regarding a phase comparison stage fed by phasors provided with the T2KF. In this paper, the proposed filter improves the relays steady-state and transient responses, in comparison with the well-known Fourier and Cosine filter, since the T2KF filter avoids fluctuations that may lead to overreach and underreach problems. The results are carried out in order to assess the proposed application.
Use of peaks and troughs in the horizontal-to-vertical spectral ratio of ambient noise for Rayleigh-wave dispersion curve picking
Journal of Applied Geophysics
José Piña Flores 1 , Martín Cárdenas Soto 1 , Antonio García Jerez 2 , Helena Seivane 2 , Francisco Luzón 2 , Francisco José Sánchez Sesma 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad de Almería, Departamento de Química y Física
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: ambient seismic noise, Rayleigh waves, joint inversion, HVSR
Abstract: To assist in the identification of fundamental-mode dispersion curves of Rayleigh waves in dispersion diagrams, we explore the relation between the shape of the horizontal-to-vertical spectral-ratio (HVSR) of ambient seismic noise and the shape of the dispersion curves for phase and group velocities in a stratified medium. We propose to use the information coming from the HVSR to identify the osculation zones and multi-mode effects and to locate inflection points and critical points in the observed phase and group dispersion diagrams of Rayleigh waves. The relationship between these curves has been numerically investigated for some models consisting of one and two homogeneous layers overlying a half-space, with velocities increasing downwards. It is primarily found that the first minimum in the HVSR appears close to the frequency of the inflection point of the fundamental mode of phase velocity. In addition, the osculation and multimode effects occur between frequencies of the fundamental peak and the first minimum of the HVSR. On the other hand, the frequencies of the minima in HVSR closely approximate the critical points of the fundamental-mode group-velocity dispersion curve, even better than the inflection points of the fundamental-mode phase-velocity curve. Finally, we show an example of experimental identification of fundamental-mode phase and group dispersion curves supported by the shape of the HVSR, obtaining a reliable velocity profile through the simultaneous inversion of these three curves.
Watermarking of HDR Images in the Spatial Domain with HVS-Imperceptibility
IEEE Access
Karina Ruby Pérez Daniel 1 , Francisco Javier García Ugalde 2 , Víctor Sánchez Silva 3
1 Universidad Panamericana, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 University of Warwick, Department of Computer Science

Keywords: HDR, invisible watermarking, visible watermarking, LVT curve, HVS-imperceptibility
Abstract: This paper presents a watermarking method in the spatial domain with HVS-imperceptibility for High Dynamic Range (HDR) images. The proposed method combines the content readability afforded by invisible watermarking with the visual ownership identification afforded by visible watermarking. The HVS-imperceptibility is guaranteed thanks to a Luma Variation Tolerance (LVT) curve, which is associated with the transfer function (TF) used for HDR encoding and provides the information needed to embed an imperceptible watermark in the spatial domain. The LVT curve is based on the inaccuracies between the non-linear digital representation of the linear luminance acquired by an HDR sensor and the brightness perceived by the Human Visual System (HVS) from the linear luminance displayed on an HDR screen. The embedded watermarks remain imperceptible to the HVS as long as the TF is not altered or the normal calibration and colorimetry conditions of the HDR screen remain unchanged. Extensive qualitative and quantitative evaluations on several HDR images encoded by two widely-used TFs confirm the strong HVS-imperceptibility capabilities of the method, as well as the robustness of the embedded watermarks to tone mapping, lossy compression, and common signal processing operations.
Efficient method for the optimal economic operation problem in point-to-point VSC-HVDC connected AC grids based on Lagrange multipliers
Electric Power Systems Research
Luis Miguel Castro González 1 , Néstor González Cabrera 1 , Daniel Guillén Aparicio 2 , José Horacio Tovar Hernández 3 , Guillermo Gutiérrez Alcaraz 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Tecnológico de Monterrey, Ingeniería Eléctrica y Electrónica
3 Instituto Tecnológico de Morelia, Posgrado en Ingeniería Eléctrica

Keywords: Economic operation, Lagrange multipliers, point-to-point VSC-HVDC links, optimal power flows, incremntal transmission loss factors
Abstract: This paper describes a method based on Lagrange multipliers for efficiently solving the economic dispatch in power systems including point-to-point VSC-HVDC links. The proposed formulation bases on linear models of the AC systems and HVDC links where power losses are properly considered through incremental transmission loss factors. This timely formulation preserves suitable outcome accuracy while showing a greater computational efficiency than what is achieved with classical, nonlinear OPF methods. Its main features are demonstrated using two compelling test cases: a system accommodating one point-to-point VSC-HVDC link and another comprising multi-infeed HVDC connected AC power grids. Results of this approach are compared with those calculated by the nonlinear interior point method. It is confirmed that both fundamentally different approaches are in good agreement since errors smaller than 0.5% were obtained for generation costs, whereas the computational time was reduced by more than 60% with the introduced method. To show the method applicability in realistic power systems, the 10-generator New England Test system incorporating a VSC-HVDC link is studied. The DC link effect on system operation is examined for a 24-hour period dispatch thus demonstrating its usefulness, unrivalled modelling versatility and numerical efficiency with respect to existing approaches.
Effective dynamic state estimation algorithm for islanded microgrid structures based on singular perturbation theory
Electric Power Systems Research
Natanael Vieyra Valencia 1 , Paul Rolando Maya Ortíz 2 , Luis Miguel Castro González 2
1 Universidad Nacional Autónoma de México, Posgrado en Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: dynamic state estimation, islanded microgrid, distributed generation, unscented Kalman filter, singular perturbation theory
Abstract: This paper introduces an effective dynamic state estimator for Islanded Microgrids. Basing on a set of nonlinear Differential Algebraic equations representing the electrical grid and the energy sources, the Singular Perturbation Theory is used to obtain a modified mathematical representation of the Microgrid model to develop an effective dynamic state estimator based on the Unscented Kalman Filter. It is shown that Singular Perturbation Theory is a viable tool that permits the design of a dynamic estimator able to effectively recover the steady-state and dynamic states of the electrical grid, that is, the nodal voltages and the dynamic variables of generator units. Furthermore, the Microgrid state is suitably recovered using fewer measurements than those needed by conventional static estimators. The performance of the proposed scheme is evaluated using a practical Microgrid containing wind power and hydroelectric generators, under load and wind variations as well as three-phase faults. Also, this timely approach is compared with the Extended Kalman Filter for Differential Algebraic systems, demonstrating the superior effectiveness of the developed state estimator: the errors obtained by the new dynamic state estimator are 80% smaller than those obtained by the conventional Extended Kalman Filter, for the same applied noises. Moreover, a comparative study case with the Unscented Kalman Filter is included.
Effective sensitivity-based method for N-1 contingency analysis of VSC-based MTDC power grids considering power generation droop speed controls
International Journal of Electrical Power & Energy Systems
Gabriela Álvarez Romero 1 , Luis Miguel Castro González 2 , Pedro Roncero Sánchez 3
1 Universidad Nacional Autónoma de México, Posgrado en Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad de Castilla - La Mancha, E.T.S. Ingenieros Industriales de Ciudad Real

Keywords: AC/DC grids, contingency analysis, primary frequency control, MTDC, VSC-HVDC links
Abstract: This paper introduces a sensitivity-based approach for the efficient calculation of the post-disturbance, steady-state conditions in VSC-based MTDC power grids subject to generation outages and VSC disconnections. This approach is useful for the N-1 contingency analysis, a crucial tool in power system control centres. In order to maintain a high degree of fidelity, the approach considers state-of-the-art VSC control strategies: converters with DC voltage regulation, power-injection control, DC voltage/power droop control, and converters imposing frequency regulation on passive grids. The speed-governing response of power plants is also considered, enabling accurate calculations of AC/DC power flows and AC system frequencies. Indeed, the derived sensitivity factors permit the primary frequency response of the AC systems and DC grid to be efficiently assessed, something that would require several hours of simulation by standard electromagnetic transient (EMT) simulators. Evidently, this novel approach allows a much faster calculation of the AC/DC network??s post-disturbance conditions than is possible with dynamic simulation tools. A formulation with such modelling versatility and practicality does not currently exist elsewhere. The usefulness of this novel formulation has been confirmed using an MTDC system comprising six VSC-connected AC grids and a 13-bus DC grid. The disconnections of VSC units and power plants have also been evaluated. The study shows that the post-disturbance, steady-state conditions computed by the sensitivity-based approach agree well with those obtained by full dynamic simulations, because the relative errors between the two fundamentally different methods are smaller than 0.1% for the AC system frequencies and smaller than 4% for the AC and DC transmission line power flows.
Geological Sheet Tehuacán 14Q-i-(10), Puebla and Oaxaca states, southern Mexico
Journal of Maps
Gilberto Silva Romo 1 , Claudia Cristina Mendoza Rosales 1 , Emiliano Campos Madrigal 1 , Elena Centeno García 2 , Orestes Antonio De la Rosa Mora 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Geología

Keywords: Atzumba basin, Ayuquila basin, Chivillas basin, Otlaltepec basin, Tehuacán basin, Zapotitlán basin
Abstract: This work offers a large-scale approach to the stratigraphy of an area in southern Mexico that includes three different tectono-stratigraphic terranes and displays a great geological diversity. In the attached 1:100,000-scale geological map, the stratigraphic information is grouped according to the occurrence in sedimentary basins. Here, we describe the basement and six basins in turn. In four of the sedimentary basins, thick Mesozoic successions that accumulated on the basement record the evolution from a continental environment during the Triassic??Jurassic, to a marine environment, comprising clastic and calcareous deposits, during the early Cretaceous. Cenozoic ages are recorded in clastic and lacustrine sedimentary successions and in abundant igneous rocks in two of the continental basins. The geodatabase was compiled in GIS format and subsequently imported in vector graphic software to achieve a design similar to the cartographic series 1:100,000 CARTA GEOL?GICA DE M?XICO of the Instituto de Geología, UNAM.
Impact of Resistive Superconducting Fault Current Limiter and Distributed Generation on Fault Location in Distribution Networks
Electric Power Systems Research
Daniel Guillén Aparicio 1 , Cristian Salas Varona 2 , Frédéric Trillaud Pighi 3 , Luis Miguel Castro González 4 , André Tiago Queiroz 5 , Guilherme Goncalvez Sotelo 5
1 Tecnológico de Monterrey, Ingeniería Eléctrica y Electrónica
2 Universidad Nacional Autónoma de México, Posgrado en Ingeniería Eléctrica
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería
5 Universidad Federal Fluminense, Departamento de Energía Eléctrica

Keywords: Distributed generation, distribution network, fault location, resistive superconducting fault-current limiter
Abstract: Resistive Superconducting Fault-Current limiters (r-SFCL) appear as a new attractive technology to address faults in power grids. Based on a new generation of superconductors, referred to as High-Temperature Superconductors (HTS), they could offer economical benefits compared to more conventional technologies. To understand their impact on the electrical networks, two models of r-SFCL, differing by their complexity, were built to conduct short-circuit analysis. Different fault locations in distribution networks were studied in the standard IEEE 13-node and 34-node test feeders. Both models were validated against experimental data and then cross-checked in the IEEE 13-bus distribution system to determine their relative accuracy when used in practical power grids. Subsequently, using the simplest electrical model of r-SFCL, the 34-bus test system incorporating Distributed Generation (DG) was used to analyze short circuits. It was found that the presence of r-SFCL increases the error of the fault location algorithm. However, it was also demonstrated that a single r-SFCL enables the incorporation of several additional DG in a distribution network by reducing the fault current level by at least 45% depending on its design characteristics and the number of added DG. Finally, an improved algorithm is presented. This algorithm takes into account the r-SFCL resistance in order to reduce the fault location error.
Robust output tracking of constrained perturbed linear systems via model predictive sliding mode control
International Journal of Robust and Nonlinear Control
Martin Steinberger 1 , I. Castillo 2 , Martin Horn 3 , Leonid Fridman Golredich 2
1 Graz University of Technology, Institute of Automation and Control
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Graz University of Techonology, Institute of Automation and Control

Keywords: linear model predictive control, output integral sliding mode, output tracking, sliding mode control
Abstract: A robustifying strategy for constrained linear multivariable systems is proposed. A combination of tracking model predictive control with output integral sliding mode techniques is used to completely reject bounded matched perturbations. It can be guaranteed that all constraints on inputs, states, and outputs are satisfied although only output information is used. Finally, real?world experiments with an unstable plant are presented in order to demonstrate the validity and the effectiveness of the proposed approach.
On the Dynamic Modeling of Marine VSC-HVDC Power Grids Including Offshore Wind Farms
IEEE Transactions on Sustainable Energy
Luis Miguel Castro González 1 , Enrique Acha Daza 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Tampere University of Applied Sciences, Faculty of Information Technology and Communication Sciences - Electrical Engineering

Keywords: AC/DC networks, DFIG, power system dynamic simulations, VSC-HVDC grids, offshore wind farms
Abstract: This article presents a new and comprehensive modeling framework to carry out system-wide dynamic studies of DFIG-based wind farms embedded in multi-terminal VSC-HVDC power grids. Contrary to existing, well-developed simulation frameworks for similar studies, using electromagnetic transient (EMT) solutions, this is an RMS-type formulation which maintains a high-degree of fidelity while enabling much faster steady-state and dynamic simulations than what it is possible to achieve with EMT simulators. The new RMS modeling framework includes AC/DC power grids of an arbitrary size, topology and number of offshore VSC-connected wind farms. A simulation tool with such a high degree of modeling versatility and numerical efficiency does not currently exist elsewhere. This has required the development, using first principles, of the RMS model of a DFIG with explicit representation of all the dynamic effects relevant for dynamic problems of the electromechanical type as opposed to the study of very fast EMT phenomena. All the control functions and parameters of the rotor-side converter, the grid-side converter and the DC link, are accounted for in the new DFIG model. The prowess of the new formulation is demonstrated using a six-terminal VSC-HVDC link with two VSC-connected 200-MW wind farms. The impact of the wind farms' operation on both the DC grid and the AC grids is assessed. The fidelity of the output results of the new simulation tool is compared against those of the EMT-type model implemented in Simscape Electrical of Simulink. The article shows that they favorably compare with each other, with differences inferior to 3%. The computational efficiency of the new dynamic modeling framework for HVDC-connected wind farms is unassailable.
Dynamic State Estimation for Microgrid Structures
Electric Power Components and Systems
Natanael Vieyra Valencia 1 , Paul Rolando Maya Ortíz 2 , Luis Miguel Castro González 2
1 Universidad Nacional Autónoma de México, Posgrado en Ingeniería Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: dynamic state estimation extended Kalman filter, islanded microgrids differential algebraic equations, wind generators
Abstract: In this article, the dynamic state estimation of the islanded microgrids problem is addressed. The electrical network and energy sources are represented as a set of Nonlinear Differential Algebraic Equations, with the aim to capture the nonlinear phenomena and a novel solution, by using a variation of the Kalman Filter ad hoc for differential algebraic systems, is presented. In this representation, the state is given by the voltage phasors at each bus and the variables related to the energy sources. The proposed algorithm permits not only to effectively obtain an estimate of the state variables but also it allows to recover these variables during the microgrid transient behavior. Moreover, the estimation may be carried out using fewer measurements than those needed by conventional static estimators. The performance of the proposed dynamic state estimator is evaluated via numerical experiments using two practical microgrids containing wind power and hydroelectric generators. This novel method has been tested for load variations and wind speed changes demonstrating its capabilities and efficiency.
SICIoT: A simple instruction compiler for the Internet of Things
Internet of Things
Angel Zúñiga 1 , Gerardo Sierra 1 , Gemma Bel Enguix 1 , Javier Gómez 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: With the advent of IoT and the recent explosion in the number of smart devices, it has become necessary to have a simple and intuitive interface for people to operate them. The vast majority of end-users interacting with IoT devices in the future will be ordinary people (without any technical knowledge), with access to only certain basic operations already preprogrammed in the IoT devices (factory default settings). The possibility of changing the IoT device behavior (i.e., programming) beyond the factory-default, is almost completely restricted to expert technical people. A simple instruction compiler that can translate straightforward verbal instructions into a new IoT device functionality is presented in this paper. Several case examples are shown and, as proof of concept, a prototype using IoT hardware is developed. These examples show how an ordinary user can benefit significantly from this compiler by developing a specific basic application that meets their needs. To the best of the authors?? knowledge, all related works have focused on developing tools for such new devices. The solution proposed in this work is the first one focused on ordinary people as the target users. This solution intends to be the starting point of future extensions dedicated to supporting, incrementally, more and more instructions, as required.
A data fusion approach of physical variables measured through a wireless sensor network
Research in Computing Science
Thomas Alejandro Arias Pelayo 1 , Guillermo Molero Castillo 1 , Ismael Everardo Bárcenas Patiño 1 , Rocío Aldeco Pérez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Data Fusion, Monte Carlo Method, Wireless Sensor Network, Physical Variables
Abstract: At present, current data fusion methods are a useful tool for integrating data sources, prior to data analytics, and provide a unified view of an observed phenomenon or event. This paper presents the development of the Monte Carlo method, as a data fusion mechanism, obtained from a wireless sensor network. This network of sensors was designed and installed in a closed environment of human occupation. The data collected was of physical variables, such as temperature, humidity, and dust density, which were stored in the cloud through ThingSpeak, which is an open-source platform for the Internet of Things. As a result, it was succeeded in data fused properly and the method was evaluated through the root-mean-square error. Undoubtedly, fused values can be useful, for example, for the analysis of the thermal comfort of users in closed environments, where there are minimal ventilation rates and adequate indoor air quality is needed.
A Lyapunov Approach to Barrier-Function Based Time-Varying Gains Higher Order Sliding Mode Controllers
Cornell University
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: Time varying sliding mode, Lyapunov-based time varying controllers, Finite time stabilization, Perturbed integrator chain, Unknown bounded uncertainties.
Abstract: In this paper, we present Lyapunov-based {\color{black}time varying} controllers for {\color{black}fast} stabilization of a perturbed chain of integrators with bounded uncertainties. We refer to such controllers as {\color{black}time varying} higher order sliding mode controllers since they are designed for nonlinear Single-Input-Single-Output (SISO) systems with bounded uncertainties such that the uncertainty bounds are unknown. %{\color{blue} OLD: Our main result states that, given any neighborhood ε of the origin, we determine a controller insuring, for every uncertainty bounds, that every trajectory of the corresponding closed loop system enters ε and eventually remains there. Furthermore, based on the homogeneity property, a new asymptotic accuracy, which depends on the size of ε, is presented.} We provide a time varying control feedback law insuring verifying the following: there exists a family (D(t))t?0 of time varying open sets decreasing to the origin as t tends to infinity, such that, for any unknown uncertainty bounds and trajectory z(??) of the corresponding system, there exists a positive positve tz for which z(tz)??D(tz) and z(t)??D(t) for t?tz. %enters convergence in finite time of all the trajectories to a time varying domain D(t) shrinking to the origin and their maintenance there. Hence, since the function η(t) tends to zero, this leads the asymptotic convergence of all the trajectories to zero. The effectiveness of these controllers is illustrated through simulations.
A Note on Constructive Interpolation for the Multi-Modal Logic Km
Electronic Notes in Theoretical Computer Science
Everardo Bárcenas 1 , José de Jesús Lavalle Martínez 2 , Guillermo Molero Castillo 1 , Alejandro Velázquez Mena 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Benemérita Universidad Autónoma de Puebla

Keywords: Craig Interpolation, Multi-modal logic Km, Tree-Hypersequents, Beth Definability, Robinson Joint Consistency
Abstract: The Craig Interpolation Theorem is a well-known property in the mathematical logic curricula, with many domain applications, such as in the modularization of formal specifications and ontologies. This property states the following: given an implication, say formula ? implies another formula ?, then there is a formula β, called the interpolant, in the common language of ? and ?, such that ? also implies β, as well as β implies ?. Although it is already known that the propositional multi-modal logic Km enjoys Craig interpolation, we are not aware of method providing an explicit construction of interpolants. We describe in this paper a constructive proof of the Craig interpolation property on the multi-modal logic Km. Interpolants can be explicitly computed from the proof. Furthermore, we also describe an upper bound for the computation of interpolants. The proof is based on the application of Maehara technique on a tree-hypersequent calculus. As a corollary of interpolation, we also show Beth definability and Robinson joint consistency.
Adaptive neuronal induction motor control with an 84?pulse voltage source converter
Asian Journal of Control
Francisco Beltrán 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

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.
An adaptive neural online estimation approach of harmonic components
Electric Power Systems Research
Francisco Beltrán Carbajal 1 , Rubén Tapia Olvera 2
1 Universidad Autónoma Metropolitana, Unidad Azcapotzalco
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Harmonics, Online estimation, Offset estimation, Neural networks, Adaptive estimation
Abstract: An asymptotic online estimation approach of significant harmonics and DC offset component of multi-frequency oscillating electric signals based on B-spline artificial neural networks is proposed. Harmonics are considered as unknown outputs or vibration modes of a vibrating system. Thus, a vibrating signal model is structurally used for real-time estimation design purposes of unknown terms constituting multiple frequency electric oscillations. In this fashion, harmonic outputs and DC offset are estimated using measurements of some available electric signal. B-spline neural networks are properly employed to compute online an adaptive unique estimator gain in presence of harmonic uncertainty. Analytical and numerical results prove the effectiveness of the artificial neural estimation for constitutive terms of electric oscillations.
Assessing Synchrophasor Estimates of an Event Captured by a Phasor Measurement Unit
IEEE Transactions on Power Delivery
José Antonio De la O Serna 1 , Mario Roberto Arrieta Paternina 2 , Alejandro Zamora Méndez 3
1 Universidad Autónoma de Nuevo León, Departamento de Ingeniería Electrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica

Keywords: Frequency, O-splines, phasor measurement unit, rate of change of frequency, synchrophasors, total vector error
Abstract: Synchrophasor estimators are nowadays evaluated with the Total Vector Error (TVE) using the synchrophasor representations of the few benchmark signals. This synchrophasor dependence prevents its application to power signals of real events. A new method to obtain the synchrophasor of real signals is proposed in this paper. A finite impulse response (FIR) filter, designed with the nonic O-spline is proposed to obtain phasor estimates asymptotically close to those of an ideal bandpass filter. The phasor estimation accuracy of one or several Phasor Measurement Units (PMUs) can be then assessed using the standard. In addition, it is possible to design two FIR differentiators to obtain frequency and ROCOF estimates close enough to those of ideal differentiator filters, and largely compliant with the standard. This new set of filters opens the way to apply the synchrophasor standard to assess estimates of PMUs of different brands when they process the same signals of a power system event. In this paper, the erratic phasor and frequency estimates produced by a SEL-351A PMU from a real distributed generation system are assessed to corroborate that the synchrophasor standard can be opened to this new application based on real signals from the field, previously considered as impossible.
A New Class of Uniform Continuous Higher-Order Sliding Mode Controllers
Journal of Dynamic Systems, Measurement, and Control
Shyam Kamal 1 , P. Ramesh Kumar 2 , Asif Chalanga 1 , Jitendra Kumar Goyal 3 , Bijnan Bandyopadhyay 1 , Leonid Fridman Golredich 4
1 Indian Institute of Technology, Systems and Control Engineering
2 Government Engineering College, Department of Electrical Engineering
3 Indian Institute of Technology, Department of Electrical Engineering
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Algorithms, Control equipment, Design, Yaw
Abstract: This paper proposes a new class of uniform continuous higher-order sliding mode algorithm (UCHOSMA) for the arbitrary relative degree systems. The proposed methodology is a combination of two controllers where one of the components is a uniform super-twisting control which acts as the disturbance compensator and the second part gives the uniform finite time convergence for the disturbance free system. This algorithm provides uniform finite time convergence of the output and its higher derivatives using an absolutely continuous control signal and thus alleviating the chattering phenomenon. The attractive feature of the proposed controller is that irrespective of the different initial conditions, the control is able to bring the states of the system to the equilibrium point uniformly in finite time. The effectiveness of the proposed controller has been demonstrated with both simulation and experimental results.
Comparison and ranking of metaheuristic techniques for optimization of PI controllers in a machine drive system
Applied Sciences
Omar Aguilar Mejía 1 , Herwin Minor Popocatl 1 , Rubén Tapia Olvera 2
1 Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: PMSM, swarm intelligence, optimization
Abstract: Proportional integral (PI) control is still the most widely deployed controller in the industrial drives due to its simplicity and the fact that it is easy to understand and implement. Nevertheless, they are successes applied to systems with a complex behavior with a nonlinear representation, but a disadvantage is the procedure to find the optimal PI controller gains. The optimal values of PI parameters must be computed during the tuning process. However, traditional tuning techniques are based on model and do not provide optimal adjustment parameters for the PI controllers because the transient response could produce oscillations and a large overshoot. In this paper, six swarm intelligence-based algorithms (whale, moth-flame, flower pollination, dragonfly, cuckoo search, and modified flower pollination), are correctly conditioned and delimited to tune the PI controllers, the results are probed in a typical industry actuator. Also, a rigorous study is developed to evaluate the quality and reliability of these algorithms by a statistical analysis based on non-parametric test and post-hoc test. Finally, with the obtained results, some time simulations are carried out to corroborate that the nonlinear system performance is improved for high precision industrial applications subjected to endogenous and exogenous uncertainties in a wide range of operating conditions.
Exact differentiators with assigned global convergence time bound
Cornell University
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 the considered class of differentiators includes as a special case.
Flash Flood Early Warning System in Colima, Mexico
José Ibarreche 1 , Raúl Aquino Santos 1 , Robert Edwards 2 , Víctor Rangel Licea 3 , Ismael Pérez 1 , Miguel Martínez 4 , Esli Castellanos Berjan 1 , Elisa Álvarez 1 , Saul Jiménez 5 , Raúl Renteria 6 , Arthur Edwards 1 , Omar Álvarez 1
1 Universidad de Colima, Facultad de Telemática
2 Loughborough University, 5G Research Centre
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Universidad de Colima, Facutad de Ingeniería Civil
5 Corporativo STR S.A. de C.V.
6 Tairda S.A. de C.V.

Keywords: real-time early warning, flash flooding, internet of things
Abstract: This paper presents a system of sensors used in flash flood prediction that offers critical real-time information used to provide early warnings that can provide the minutes needed for persons to evacuate before imminent events. Flooding is one of the most serious natural disasters humans confront in terms of loss of life and results in long-term effects, which often have severely adverse social consequences. However, flash floods are potentially more dangerous to life because there is often little or no forewarning of the impending disaster. The Emergency Water Information Network (EWIN) offers a solution that integrates an early warning system, notifications, and real-time monitoring of flash flood risks. The platform has been implemented in Colima, Mexico covering the Colima and Villa de Alvarez metropolitan area. This platform consists of eight fixed riverside hydrological monitoring stations, eight meteorological stations, nomadic mobile monitoring stations called "drifters? used in the flow, and a sniffer with data muling capability. The results show that this platform effectively compiles and forwards information to decision-makers, government officials, and the general public, potentially providing valuable minutes for people to evacuate dangerous areas.