Multivariable extension of global finite time HOSM based differentiator for output-feedback unit vector and smooth binary control
Asian Journal of Control
https://doi.org/10.1002/asjc.2030
Tiago Roux Oliveira 1 , Víctor Hugo Pereira Rodrigues 1 , Andrei Battistel 1 , Leonid Fridman Golredich 2
1 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering

Keywords: binary adaptive control, exact tracking, global stability, MIMO global HOSM differentiator, output feedback, unit vector sliding mode control
Abstract: In this paper, we propose a unit vector control law by output feedback to solve the problem of global exact output tracking for a class of multivariable uncertain plants with nonlinear disturbances. In order to face the nonuniform arbitrary relative degree obstacle, we extend our earlier estimation scheme based on global finite?time differentiators using dynamic gains to a multivariable architecture. A diagonally stable condition over the system high?frequency gain (HFG) matrix has to be assumed. Preserving the simplicity of its mono variable framework, variable gain super?twisting algorithm (STA) is employed to obtain the robust and exact multivariable differentiator. Moreover, state?norm observers for the unmeasured state variables are constructed to upper bound the disturbances as well as to update the differentiator gains, being both state dependent. Uniform global exponential stability and ultimate exact tracking are proved. As an alternative to chattering alleviation, we appeal to the Emelyanov's concept of binary control in order to obtain a continuous control signal replacing the unit vector function in the controller by a high?gain gradient adaptive law with parameter projection. As shown in the existing literature for mono variable systems, the proposed multiparameter binary?adaptive formulation tends to the unit vector control as the adaptation gain increases to infinity, also smoothing the transition from adaptive to sliding mode control. A numerical example is portrayed to illustrate the potentialities of the developed multivariable techniques.
Design of super-twisting control gains: A describing function based methodology
Automatica
https://doi.org/10.1016/j.automatica.2018.10.023
Ulises Pérez Ventura 1 , Leonid Fridman Golredich 1

Keywords: Sliding-mode control, Chattering, Harmonic balance
Abstract: The Describing Function approach is used to adjust the parameters of fast-oscillations (chattering) caused by the presence of fast-actuators in Super-Twisting control loops. Estimated parameters, amplitude and frequency of self-excited oscillations, allow to compute the average power needed to maintain the trajectories of the system into real sliding-modes. Through the parametrization of the actuator dynamics by a critically damped second-order system or by a constant delay, sets of STA gains are provided to minimize the amplitude of oscillations or the average power. The results are confirmed by simulations.
Dexterous remote manipulation by means of a teleoperation system
Robotica
https://doi.org/10.1017/S0263574719000055
Javier Pliego Jiménez 1 , Marco Antonio Arteaga Pérez 2 , César Cruz Hernández 1
1 CICESE, División de Física Aplicada

Keywords: Dexterous manipulation, Teleoperation, Force control, Robot manipulator
Abstract: Humans are experts in manipulation and grasping tasks. However, several industrial tasks represent a risk to human operators, for instance, handling radioactive material or transporting heavy objects. Teleoperation robotic schemes extend human capabilities, but they are highly nonlinear systems. In this paper, we address the problem of dexterous remote manipulation by means of a unilateral heterogenous teleoperation scheme composed by a single-master and multiple-slave manipulators handling a rigid object. In order to achieve a stable grasp, a decentralized force/position controller with continuous and bounded input torques based on the Orthogonalization Principle and a second-order sliding mode control is proposed for the slave robots. In addition, a trajectory planning method based on holonomic constraints is proposed to control multiple-slave manipulators with a single-master device. Experimental results are presented to evaluate the performance of the proposed approach.
Provenance inferred through modern beach sands from the Gulf of Tehuantepec, Mexico
Geological Journal
https://doi.org/10.1002/gj.3205
Arturo Carranza Edwards 1 , Juan José Kasper Zubillaga 1 , Raymundo G. Martínez Serrano 2 , Mayumi Amparo Cabrera Ramírez 3 , Leticia Rosales Hoz 1 , Miguel Angel Alatorre Mendieta 1 , Antonio Z. Márquez García 4 , Rufino Lozano Santa Cruz 5
1 Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología
2 Universidad Nacional Autónoma de México, Instituto de Geofísica
5 Universidad Nacional Autónoma de México, Instituto de Geología

Keywords: beach sands, geochemistry, grain size, Gulf of Tehuantepec, Mexico, petrology, provenance
Abstract: Different parent rocks, climate, and relief control the provenance of beach sands on the coast of Mexico. This is the first paper to address the provenance problem of beach sands in south-eastern Mexico considering a homogeneous climate and relative similarity in parental rocks but different relief. Two coastal areas are confined in this study: (a) the Western Gulf of Tehuantepec (WGT) and (b) the Eastern Gulf of Tehuantepec (EGT). The WGT beach sands are probably controlled by the denudation of orthogneisses, Eocene??Miocene basaltic??andesites??dacites??rhyolites from the Volcanic Belt of the Sierra Madre del Sur (VBSMS), and granites to diorites from the Coastal Plutonic Belt (CPB). The rocks exposed in the EGT are represented by orthogneisses and tonalite, granodiorite, and gabbro suites from the Palaeozoic??Mesozoic Chiapas Coastal Plutonic Belt (CHCPB). Quaternary andesites and dacites from the Tacaná Volcano are located in the eastern coastal area. The Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values indicate that the less weathered beach sands are in the WGT compared to the EGT coastal area. Plagioclase transport is preserved in a narrow coastal plain that contributes to a lower a weathering rate compared to the EGT sands deposited in a wider coastal plain. Geochemical analyses show that the WGT and EGT beach sands are admixtures of felsic, intermediate, metamorphic, and volcanic sources in their sands composition. Relief seems to play a major role in the composition of beach sand in both coastlines, since parental rocks are mostly similar in composition and climate remains homogeneous along the coast.
Reactor behavior comparisons for two liquid metal-cooled fast reactors during an event of loss of coolant
Case Studies in Thermal Engineering
https://doi.org/10.1016/j.csite.2019.100556
Alejandría D. Pérez Valseca 1 , Sergio Quezada García 2 , Armando M. Gómez Torres 3 , Alejandro Vázquez Rodríguez 4 , Gilberto Espinosa Paredes 1
1 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
3 Instituto Nacional de Investigaciones Nucleares

Keywords: Liquid metal-cooled fast reactors, Lead-cooled fast reactor, Sodium-cooled fast reactor, Unprotected loss-of-flow, Subchannel analysis
Abstract: The aim of this paper is to present a fast-numerical tool based on the average channel approach to analyze the response of fast reactors under unprotected loss of flow events. The comparison of the transient behavior of a Lead-cooled Fast Reactor and a Sodium-cooled Fast Reactor during a loss of flow event is presented. The coolant flow to the core inlet was reduced to 90%, 70% and 50% of the nominal value. The parameters compared were power, fuel, cladding, and coolant temperatures, as well as heat removal. In order to compare the results between both reactors, the values of neutronic density and removed heat obtained during the transient were normalized with respect to the values in the steady state, as a result, the percentages of increase or decrease of the parameters selected for the model were analysed. In the case of analysis of fuel, gap, clad and coolant, the increments of temperature are presented. With the obtained results, the capacity of the coolants for the removal of the heat generated during the transient can be identified. Therefore, lead has a better capacity to remove heat in fast nuclear reactors.
Physical Parameterization of IDF Curves Based on Shorth-Duration Storms
Water
https://doi.org/10.3390/w11091813
Alfonso Gutiérrez López 1 , Sergio Bernardo Jiménez Hernández 2 , Carlos Agustín Escalante Sandoval 3
1 Universidad Autónoma de Querétaro, Centro de Investigaciones del Agua-Querétaro

Keywords: IDF curves, short duration storms, Sherman equation, scale factor, Mexico
Abstract: Intensity??duration??frequency (IDF) curves are empirical mathematical formulations that have been used for years in engineering for planning, design, and operation of hydraulic projects. The expression proposed by Sherman (1931) has been validated and used largely by many researchers. In all cases, the four parameters of this formulation are obtained through a numerical procedure. Although these parameters are obtained from historical rainfall observations, the optimization of these parameters implies an infinite combination between them and all those solutions would be valid. Of the four parameters, only one of them (C) has units, and for this reason, a physical sense of parameter C is searched for. Having certainty that some of them can be measured in situ would represent a great advance for modern hydrology. With data from 523 storms monitored every minute, a parametric adjustment was made to the Sherman equation and the typical duration of storms at each site was also obtained. To demonstrate how rainfall intensities vary with the change in C value, rainfall intensities calculations for of 5, 10, 15, and 20 min rainfall duration are used to validate the proposed methodology. The results show that typical storm duration is correlated with the additive parameter of Sherman??s formula.
Conjugate thermal-hydrodynamic model for the study of heavy oil transport
Journal of Petroleum Science and Engineering
https://doi.org/10.1016/j.petrol.2019.04.083
Salvador Sánchez 1 , Gabriel Ascanio 1 , José Felipe Sánchez Minero 2 , Federico Méndez Lavielle 3 , Juan Pablo Aguayo Vallejo 1 , Edgar Ramírez Jiménez 2 , G. Alonso Ramírez 2
1 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Química e Industrias Extractivas

Keywords: temperature-dependent properties, Dynamic viscosity, Scale analysis, Conjugate phenomenon, Lubrication theory
Abstract: In the present work, the thermal impact induced by the environment on the hydrodynamics of heavy oil transport in pipelines is analyzed. Here, the thermal dependence of the dynamic viscosity of heavy oils, in addition to the mechanical heating caused by viscous dissipation are taken into account; therefore, the mathematical models that represent the flow and temperature fields of the heavy oil have to be solved in a coupled manner. Moreover, given that the pipeline is protected by a thermal insulation (soil), the domain of study defines a conjugate system between the heavy oil, the pipeline and the soil, which indicates that before knowing the temperature in the fluid region, temperatures in the other two zones must be calculated. To define properly how thermal energy is transferred and generated during the crude oil transport, the analysis is carried out in dimensionless form, solving the conjugate mathematical model by using numerical approaches and simplified asymptotic approximations. The main results reveal that the transport of heavy oils is seriously affected by a small reduction in temperature, increasing substantially the dynamic viscosity and the flow rate is reduced significantly in comparison with the case of a full thermal insulation condition. Then, we can infer that when the losses of thermal energy and its effects on the hydrodynamics are controlled, an efficient transport process is obtained. Employing the asymptotic analysis, results show that such a condition can be achieved by two ways: the first one by improving the thermal insulation, and the second one by optimizing the ratio of the internal radius to the length of the pipeline or increasing the volumetric flow rate, which indicates that the conjugate phenomenon is a modified version of the Graetz-Nusselt problem.
Effect of temperature-dependent properties on electroosmotic mobility at arbitrary zeta potentials
Applied Mathematical Modelling
https://doi.org/10.1016/j.apm.2018.11.050
Carlos Vargas 1 , Oscar Eladio Bautista Godínez 2 , Federico Méndez Lavielle 3
1 Instituto Politécnico Nacional, ESIME Azcapotzalco
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Regular perturbation, Temperature-dependent zeta potential, Arbitrary zeta potential, Electroosmotic mobility
Abstract: A theoretical analysis to determine the electroosmotic mobility in an electroosmotic flow (EOF) in a microchannel at arbitrary zeta potentials is conducted in this study. As an important characteristic in this work, we consider that the wall zeta potentials of the microchannel and the viscosity and electrical conductivity of the electrolyte solution vary with temperature. The flow and the electric and temperature fields are obtained using lubrication approximation theory (LAT) together with the application of the regular perturbation technique. The electroosmotic mobility is evaluated, showing an increase higher than 18% (for the values of the physical properties used in this work) when physical properties, including the zeta potential of the microchannel walls, are considered as temperature-dependent functions compared with the isothermal case. Additionally, we show that the volumetric flow rate is drastically influenced when the zeta potential varies with temperature.
Environmental Effects on Electronic Devices in Mexico
Materials Sciences and Applications
https://doi.org/10.4236/msa.2019.103020
Francisco Sánchez Pérez 1 , Armando Ortiz Prado 1

Keywords: Atmospheric Corrosion, Damage, Electronic Devices, Degree of Atmospheric Corrosion, Corrosivity Map
Abstract: This paper shows the results of the assessment of impairment suffered by elements of electronic equipment by environmental effects in different climatic zones of Mexico. For this study, evaluated devices were evaluated that are mostly exposed under different climatic conditions of operation, to determine the degree of damage suffered which leads to malfunction, reduced service life and loss of information in some cases. The main contribution is to identify the causes of the deterioration to delay the effect of atmospheric corrosion deterioration in electronic components. The Mexican Republic has a wide range of climates and subclimates over its territory, sampling was performed for each one of the most representative regions, by their nature tend to be more conducive to the release of corrosive effect on the computer and electronic devices. For the determination of existing impairment in electronic equipment, a methodology is proposed for the evaluation of samples taken from each region, determining the degree of corrosion that exists in these devices. It should be noted that according to the literature, the main pollutants that lead to the deterioration caused by corrosive environmental phenomena are SO2, NOx, CO, CO2, coupled with the presence of ozone and chloride, characteristic of the coastal region, combined with the percent relative humidity (% HR), and temperature cycles as reported by environmental monitoring systems in Mexico. With the study of atmospheric corrosivity in electronic devices has been determined: 1) Design and operation of chamber to accelerated atmospheric corrosion testing. 2) Identification of electronic components with increased susceptibility to corrosive phenomena under typical environmental different regions of Mexico. 3) Correlation of damage suffered in electronic equipment under typical operating conditions and accelerated tests. 4) Determining the degree of atmospheric corrosion on electronic equipment. 5) Construction of atmospheric corrosivity map for Mexico in electronic devices.
Influence of longitudinal heat conduction effects in a heat sink over the thermal creep in a microchannel: conjugate heat transfer mechanism
Heat Transfer Research
https://doi.org/10.1615/HeatTransRes.2018025932
Ian Guillermo Monsivais Montoliu 1 , José Lizaldi 2 , Federico Méndez Lavielle 1
2 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: thermal creep, microchannel, conjugate heat transfer, FEM
Abstract: In this work, we use asymptotic and numerical techniques to analyze the conjugated heat transfer between a rarified gas flow and the lower wall of a thin horizontal microchannel exposed to a uniform heat flux, when the laminar motion of the gas is only caused by the thermal creep or transpiration effect on the lower wall of the microchannel. The surface temperature of the lower wall is unknown and must be determined as a part of the problem. Therefore, we can assume that the lower face of this heat sink with finite values of the thermal conductivity and thickness is exposed to a uniform heat flux, while the upper wall of the microchannel is subjected to a prescribed thermal boundary condition. The resulting governing equations are written in dimensionless form, assuming that the Reynolds number associated with the characteristic velocity of the thermal creep and the aspect ratio of the microchannel, are both very small. The velocity and temperature profiles of the gas phase and the temperature profile of the solid wall are determined as functions of the involved dimensionless parameters, and the predictions clearly confirm the influence of the conjugate thermal mechanism.
Numerical analysis for temperature changes in an electro-osmotic flow in a microchannel
Journal of Thermophysics and Heat Transfer
https://doi.org/10.2514/1.T5489
José Lizaldi 1 , Edgar Ali Ramos Gómez 2 , Federico Méndez Lavielle 2
1 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords:
Abstract: This paper presents new numerical predictions for an electro-osmotic flow circulating in a slit microchannel when the influence of local temperature field caused at least by the Joule effect can alter the flow pattern. Taking into account that the Debye length depends on temperature T, the above length should be used with caution because it appears in any electro-osmotic mathematical model. In fact, the dependence of the Debye length on the temperature field can generate additional temperature gradients along the microchannel, and the isothermal hypothesis is no longer valid, modifying the resulting governing equations. These terms are enough to change the electric potential and the flow field. Therefore, the Navier??Stokes equations, together with the energy, Poisson, and Ohmic current conservation equations, are solved using the finite element method. For this purpose, a dimensionless thermal parameter, α, which measures the temperature deviations of a reference temperature, has been introduced. The numerical predictions show that the volumetric flow rate decreases in comparison with a uniforme Debye length, and strong induced pressure gradients are sensibly altered by the existence of this parameter.
Shear Wave Velocity Estimation by a Joint Inversion of HVSR and f-k Curves under Diffuse Field Assumption: A Case Study of Sobradinho Landslide
Anuário do Instituto de Geociências
http://dx.doi.org/10.11137/2019_1_742_750
Yawar Hussain 1 , Martín Cárdenas Soto 2 , Rogério Elias Uagoda Soares 3 , Salvatore Martino 4 , Nelson Padron Sánchez 3 , César Augusto Moreira 5 , Hernán Martínez Carvajal 6
1 University of Brasilia, Department of Civil and Environmental Engineering
3 University of Brasilia, Department of Geography
4 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks
5 Universidad Estatal Paulista, Geosciences and Exact Sciences Institute

Keywords: ambient seismic noise, rheology, slip surface
Abstract: Brazilian landslides are characterized as shallow, clay rich and are commonly triggered by the summer rainfalls. Therefore, the landslide geological information, such as shear surface location, has a paramount importance in their mechanism comprehension. The most adapted methods for the estimation of shear wave velocity profile are borehole stratigraphic logs or Standard Penetration Test (SPT) and Cone Penetration Test (CPT). However, the present study applied shear wave velocity estimation of Sobradinho landslide (SLS) by a joint inversion of horizontal to vertical spectral ratio (HVSR) curve and dispersion curve (DC) extracted from frequency-wavenumber (f-k) analysis of ambient noise records. HVSR curves at all the stations in the area exhibit the ubiquitous resonance frequency peak at 2 Hz indicates that at these stations the substratum is common. The f-k results for E-W component let us obtain an acceptable DC between 5 and 7 Hz range. Finally, joint inversion was interpreted based on the diffuse field assumption. The initial model was proposed to be a three-layered over a half-space. Results of joint inversion indicate that the substratum is at 24 m depth, with Vs values close to 1500 m/s. DC defines two layers overlaying the substratum: superficial layer with velocities near to 200 m/s (7m thick), and the second layer with Vs value of 1000 m/s. We think that abrupt rheology (stiffness) change between the first and the second layer could provide an evidence of the landslide re-activation during moderate to strong rainfall events. The proposed methodology will prove a reconnaissance survey for the detailed geotechnical investigations that will confirm the obtained results. Keywords: ambient seismic noise; rheology; slip surface.
Optimal economic dispatch in microgrids with renewable energy sources
Energies
https://doi.org/10.3390/en12010181
Daniel Santillán Lemus 1 , Herwin Minor Popocatl 2 , Omar Aguilar Mejía 2 , Rubén Tapia Olvera 3

Keywords: microgrid, distributed generation, renewable energies, dynamic economic dispatch, predictive control model, mathematical programming
Abstract: Due to the opening of the energy market and agreements for the reduction of pollution emissions, the use of microgrids attracts more attention in the scientific community, but the management of the distribution of electricity has new challenges. This paper considers different distributed generation systems as a main part to design a microgrid and the resources management is defined in a period through proposed dynamic economic dispatch approach. The inputs are obtained by the model predictive control algorithm considering variations of both pattern of consumption and generation systems capacity, including conventional and renewable energy sources. Furthermore, the proposed approach considers a benefits program to customers involving a demand restriction and the costs of regeneration of the pollutants produced by conventional generation systems. The dispatch strategy through a mathematical programming approach seeks to reduce to the minimum the fuel cost of conventional generators, the energy transactions, the regeneration of polluted emissions and, finally, includes the benefit in electricity demand reduction satisfying all restrictions through mathematical programming strategy. The model is implemented in LINGO 17.0 software (Lindo Systems, 1415 North Dayton Street, Chicago, IL, USA). The results exhibit the proposed approach effectiveness through a study case under different considerations.
The effect of bone marrow on the mechanical behavior of porcine trabecular bone
Biomedical Physics & Engineering Express
https://doi.org/10.1088/2057-1976/ab4dc0
Agustín E. Bravo 1 , L. C. Osnaya 1 , E. Ramírez 1 , Víctor Hugo Jacobo Armendáriz 1 , Armando Ortiz Prado 1

Keywords: trabecular bone, marrow, mechanical properties, viscoelastic behavior, porcine
Abstract: Bone marrow plays an important role on the mechanical properties of trabecular bone. Its effect on the mechanical properties of porcine trabecular bone is studied in this paper. Uniaxial compression at a low strain rate (0.01 s??1 to 20% strain) and stress relaxation tests (600 s at 85, 70 and 55% of the max. load) were done on 90 different femur samples. Half the samples were treated to extract the bone marrow. The average pore size of the trabecular network was 0.280 ± 0.056 mm. Higher values of elastic modulus (37%), 0.2% yield stress (48%), maximum stress (39%), strain at maximum stress (54%), and toughness (300%), were found for the samples which had the bone marrow extracted and were saturated with a saline solution. A linear relation between the applied load and the relaxation stress of ${\sigma }_{rel}=0.76{\sigma }_{o}$ was found, which means that the trabecular bone behaves as a linear viscoelastic material. A mathematical approximation of the relaxation response was done using a Kohlrausch-Williams-Watts model for viscoelastic materials. Results show that it is essential to consider the viscoelastic behavior that the marrow has on the mechanical properties of the trabecular bone. The effect that the bone marrow has on the stress relaxation was found to be negligible at low strain rates and in the elastic stage of deformation.
Multiple geophysical techniques for investigation and monitoring of Sobradinho Landslide, Brazil
Sustainability
https://doi.org/10.3390/su11236672
Yawar Hussain 1 , Martín Cárdenas Soto 2 , Salvatore Martino 3 , César Augusto Moreira 4 , Welitom Borges 5 , Omar Hamza 6 , Renato Prado 7 , Rogério Elias Uagoda Soares 5 , Juan F. Rodríguez Rebolledo 1 , Rafael Cerqueira Silva 1 , Hernán Martínez Carvajal 8
1 University of Brasilia, Department of Civil and Environmental Engineering
3 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks
4 Universidad Estatal Paulista, Geosciences and Exact Sciences Institute
5 University of Brasilia, Department of Geography
6 University of Derby, College of Engineering and Technology
7 Universidad de Sao Paulo, Instituto de Astronomía

Keywords: landslide dynamic, geophysical investigation, slope mass
Abstract: Geophysical methods have a varying degree of potential for detailed characterization of landslides and their dynamics. In this study, the application of four well-established seismic-based geophysical techniques, namely Ambient Noise Interferometry (ANI), Horizontal to Vertical Spectral Ratio (HVSR), Multi-Channel Analysis of Surface Waves (MASW) and Nanoseismic Monitoring (NM), were considered to examine their suitability for landslide characterization and monitoring the effect of seasonal variation on slope mass. Furthermore, other methods such as Ground Penetrating Radar (GPR) and DC Resistivity through Electrical Resistivity Tomography (ERT) were also used for comparison purpose. The advantages and limitations of these multiple techniques were exemplified by a case study conducted on Sobradinho landslide in Brazil. The study revealed that the geophysical characterization of the landslide using traditional techniques (i.e., GPR, ERT and MASW) were successful in (i) the differentiation between landslide debris and other Quaternary deposits, and (ii) the delineation of the landslide sliding surface. However, the innovative seismic based techniques, particularly ambient noise based (HVSR and ANI) and emitted seismic based (NM), were not very effective for the dynamic monitoring of landslide, which might be attributed to the short-time duration of the data acquisition campaigns. The HVSR was also unsuccessful in landslide site characterization i.e., identification of geometry and sliding surface. In particular, there was no clear evidence of the light seasonal variations, which could have been potentially detected from the physical parameters during the (short-time) ambient noise and microseismic acquisition campaigns. Nevertheless, the experienced integration of these geophysical techniques may provide a promising tool for future applications.
Automated detection of congestive heart failure from electrocardiogram signal using Stockwell transform and hybrid classification scheme
Computer Methods and Programs in Biomedicine
https://doi.org/10.1016/j.cmpb.2019.03.008
Rajesh K. Tripathy 1 , Mario Roberto Arrieta Paternina 2 , Juan Gregorio Arrieta Paternina 3 , Alejandro Zamora Méndez 4 , Ganesh R. Naik 5
1 Siksha 'O' Anusandhan Deemed to be University, Faculty of Engineering and Technology
3 Sanatorio Güemes
4 Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Ingeniería Electrica
5 Western Sydney University, MARCS Institute

Keywords: Congestive heart failure, ECG, Stockwell transform, Time-Frequency entropy, Hybrid classifier,Performance evaluation
Abstract: Background and Objective The congestive heart failure (CHF) is a life-threatening cardiac disease which arises when the pumping action of the heart is less than that of the normal case. This paper proposes a novel approach to design a classifier-based system for the automated detection of CHF. Methods The approach is founded on the use of the Stockwell (S)-transform and frequency division to analyze the time-frequency sub-band matrices stemming from electrocardiogram (ECG) signals. Then, the entropy features are evaluated from the sub-band matrices of ECG. A hybrid classification scheme is adopted taking the sparse representation classifier and the average of the distances from the nearest neighbors into account for the detection of CHF. The proposition is validated using ECG signals from CHF subjects and normal sinus rhythm from public databases. Results The results reveal that the proposed system is successful for the detection of CHF with an accuracy, a sensitivity and a specificity values of 98.78%, 98.48%, and 99.09%, respectively. A comparison with the existing approaches for the detection of CHF is accomplished. Conclusions The time-frequency entropy features of the ECG signal in the frequency range from 11 Hz to 30 Hz have higher performance for the detection of CHF using a hybrid classifier. The approach can be used for the automated detection of CHF in tele-healthcare monitoring systems.
Introductory review of potential applications of nanoseismic monitoring in seismic energy characterization
Journal of Engineering Research (Kuwait)
https://kuwaitjournals.org/jer/index.php/JER/article/view/3735
Yawar Hussain 1 , Hernán Martínez Carvajal 2 , Martín Cárdenas Soto 3 , Salvatore Martino 4
1 University of Brasilia, Department of Civil and Environmental Engineering
4 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks

Keywords: Slide Quakes, Fracture signals, Early Warning Systems, Sonograms, Mini Array
Abstract: Major terrestrial hazards are associated with the formation of fractures that evolve with time and lead to structural collapse. The fracture singles emitted in response to stress accumulation and its release if properly understood, provide sound background for the development of Early Warning Systems (EWSs). Different attempts have been made in the past for their proper understanding, but in this study Nanoseismic (NS) monitoring is being discussed, in term of its sensors employment and signal processing modules. NS is a method dedicated to the detection, localization and characterization of very low seismic energies (Ml<1) at short distances (<10 km). Data are acquired by small aperture (max 200m) seismic arrays that are easy to install and consist of one central three component (3C) sensor surrounded by three vertical one component (1C) sensors in a tripartite layout that are suited for the beamforming processing. Detection and location of weak events (Ml<1) are done by a dedicated software: the NanoseismicSuite, which was developed at Stuttgart University, Germany. The signals are processed by sonograms (i.e. spectrograms with a frequency-dependent noise adaptation). The sonograms enhance the display of weak signal energy down to the noise threshold and allow supervised pattern recognition of weak target events in the frequency domain. Locations of weak events are supported by a graphical jackknifing approach. The case studies have shown that NM can successfully detect various weak fracture signals induced by the (stress relief mechanisms of near-surface geoprocesses) landsliding (LS) dynamic, structural health, hydraulic fracturing, erosional features, pre-mature sinkholes, pending rockfall and microseismicity associated with active faults.
Sensing, smart and sustainable product development (S3 product) reference framework
International Journal of Production Research
https://doi.org/10.1080/00207543.2017.1401237
Jhonattan Miranda 1 , Roberto Pérez Rodríguez 2 , Vicente Borja Ramírez 3 , Paul Wright 4 , Arturo Molina 1
1 Instituto Tecnológico de Estudios Superiores de Monterrey, Escuela de Ingeniería y Ciencias
4 University of California Berkeley, Mechanical Engineerign

Keywords: Industry 4.0, concurrent engineering, new product development, product life cycle, sustainable manufacturing
Abstract: Enterprises must become ??sensing, smart and sustainable (S3)?? to face global challenges related to local, national and global market dynamics. Therefore, reconceptualisation and redesign in these enterprises must accommodate emergent technologies, new practices and strategies. In this sense, enterprises have used new product development as a strategy for remaining competitive in the marketplace; thus, they can provide a new generation of products offering solutions to contemporary social problems and responding to changing consumer demands. These new-generation products are mostly technology-based and consider sustainable objectives. In this context, concepts such as sensing, smart and sustainable products (S3 products) have emerged to satisfy different social requirements. Therefore, this work focuses on providing a reference framework that presents a systematic process for the development of S3 products. This reference framework is based on the integrated product, process and manufacturing system development reference model. The main objective of this work is to fill the gap vis-à-vis the current lack of design roadmaps that permit the development of this new generation of products in S3 enterprises. The development of a reconfigurable micro-machine tool is presented as that of an S3 product.
A screening approach to improve water management practices in undeveloped shale plays, with application to the transboundary Eagle Ford Formation in northeast Mexico
Journal of Environmental Management
https://doi.org/10.1016/j.jenvman.2018.11.123
Antonio Hernández Espriú 1 , Brad Wolaver 2 , Saúl Arciniega Esparza 3 , Bridget Scanlon 2 , Michael Young 2 , Jean Philippe Nicot 2 , Sergio Macías Medrano 1 , José Agustín Breña Naranjo 3
2 The University of Texas at Austin, Jackson School of Geosciences
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Shale plays, Hydraulic fracturing, Eagle Ford, Water stress, Mexico
Abstract: Hydraulic fracturing (HF) operations have transformed the unconventional energy industry, leading to a global increase in hydrocarbon production. Despite this, only the US, China, Canada and Argentina currently dominate production of unconventional resources, with the majority of shale basins globally remaining unprofitable to develop. An important gap in current water-energy nexus research, which this study addresses, is the assessment of potential water use to satisfy HF procedures in emergent plays. This work presents a screening tool for assessing first-order estimates of water impacts in undeveloped shale plays, testing the approach in the transboundary Eagle Ford (EF) play in northeast Mexico. We couple surface water and groundwater stress indicators derived from global hydrological variables to depict a baseline water stress index. Relative water stress is mapped for proposed blocks to be leased by the Mexican government in the future. We simulate four HF scenarios to assess new total water stress indicators for each block, considering shale production schemes using representative well drilling density (well lateral length(s) per unit area) and HF water intensity (HF water volume per unit lateral length) from existing EF development in Texas. Results suggest that the most feasible management scenario would consider the drilling of ?1360 new unconventional wells/yr with projected HF water use of ?57?Mm3/yr (0.7% of the total water withdrawals). The remaining scenarios will largely affect groundwater resources. Though applied to the EF in Mexico, this screening tool can assess water use constraints in emerging unconventional plays globally.
Transient mixed convection in a channel with two facing discretely heated semicircular cavities: Buoyancy, inclination angle, and channel aspect ratio effects
Experimental Heat Transfer
https://doi.org/10.1080/08916152.2018.1517836
Faustino Pérez Flores 1 , César Treviño 2 , Israel Yescas Rosas 3 , Francisco Javier Solorio Ordaz 1 , Lorenzo Martínez Suástegui 3
3 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: arc-shape cavity, circular groove, oscillatory flows, concave-wall boundary layer, three-dimensional heat transfer
Abstract: Space-averaged surface temperature distributions and overall Nusselt number measurements have been carried out to study the transient mixed convection heat transfer in a channel with two facing and symmetrically heated semicircular cavities. Effects of buoyancy, channel orientation, and channel aspect ratio on thermal behavior have been investigated from Re 500 to 1,500. Depending on the parametric set, steady, oscillatory, and irregular thermal regimes have been identified. The natural frequencies and time scales of the oscillatory regimes have been obtained using spectral analysis. Results show that with increase in channel aspect ratio, the heat transfer performance reduces for all inclination angles.
Estimating concentrations of suspended particulate matter over the metropolitan area of Mexico City using satellite and geospatial imagery: Preliminary results
WIT Transactions on Ecology and the Environment
https://doi.org/10.2495/AIR190121
Rodrigo Takashi Sepúlveda Hirose 1 , Ana Carrera Aguilar 1 , Magnolia Martínez Rivera 1 , Pablo de Jésus Ángeles Salto 1 , Carlos Herrera Ventosa 1

Keywords: air quality, modelling pollution, particulate matter, remote sensing
Abstract: In order to diminish health risks, it is of paramount importance to monitor air quality; however, this process is accompanied by high costs of physical and human resources. This research is carried out in this context with the main objective of developing a predictive model for concentrations of inhalable particles (PM10 and PM2.5) using remote sensing. To develop the model, satellite images, mainly from Landsat 8, of the Mexico City??s metropolitan area, were used. Using historical PM10 and PM2.5 measurements of the RAMA (Environmental Monitoring Network of Mexico City) and processing the available satellite images, a preliminary model was generated in which it was possible to observe critical opportunity areas that would allow for the generation of a robust model. After applying this preliminary model to the scenes of Mexico City, three areas of great interest were identified due to their presumed high concentration of PM. The zones of interest all presented high plant density, bodies of water and bare soil without buildings or construction, or vegetation. To date, work continues along these lines to improve the proposed preliminary model. In addition, a brief analysis of six distinct models was made and presented in articles developed in different parts of the world in order to visualize the optimal bands for the generation of a suitable model for Mexico City. It was found that infrared bands have helped modelling in other cities, but the effectiveness of these bands for the specific geographic and climatic conditions of Mexico City is still in need of evaluation.
CoStorm: a term map system to aid in a collaborative ideation process
Artificial Intelligence for Engineering Design, Analysis and Manufacturing
https://doi.org/10.1017/S0890060418000215
Chengwei Zhang 1 , Marcelo López Parra 2 , Junyu Chen 1 , Ling Tian 1
1 Tsinghua University, Department of Mechanical Engineering

Keywords: Computer-aided conceptual design, decision-making, electronic brainstorming, ideation
Abstract: The decisions made during the early stages of a design process have a huge impact on a product. Owing to the explosion of preliminary ideas, however, designers easily lose track of important ideas and significant information and end up being buried in a pile of plain words. Failing to locate an idea in the context of idea generation makes it difficult to generate new ideas or take optimized decisions. In this study, the authors propose the term map approach to provide a complete bird's eye view of all ideas, which is a higher-dimension graphical representation that helps in inspiring ideas and making decisions among design team members. A software application named CoStorm is developed. Through the case study of the cash-flattener module, which is a crucial component of an automated teller machine, this method is found to contribute in facilitating the ideation and decision-making progress.
Generic Model Of Three-Phase (Re)Bco Resistive Superconducting Fault Current Limiters For Transient Analysis Of Power Systems
IEEE Transactions on Applied Superconductivity
https://doi.org/10.1109/TASC.2019.2891229
José Juan Pérez Chávez 1 , Frédéric Trillaud Pighi 2 , Luis Miguel Castro González 1 , Loïc Quéval 3 , Alexander Polasek 4 , Rubens De Andrade Junior 5
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 University of Paris-Saclay, Department of Power & Energy Systems
4 Centro de Pesquisas de Energia Eletrica
5 Universidade Federal de Rio de Janeiro

Keywords: Coils, Superconducting films, Resistance, Circuit faults, Mathematical model, Superconducting epitaxial layers, Superconducting integrated circuits
Abstract: This paper presents the modelling and implementation of a generic three-phase resistive superconducting fault current limiter (r-ScFCL) for transient analysis of ac power systems. The r-ScFCL consists of series-connected noninductive coils made of insulated commercially available (RE)BCO tapes operated in a liquid nitrogen bath, in parallel with a resistive shunt at room temperature. The model allows the prediction of the thermal and electrical behaviors of the device prior to, during, and after a fault. It was used to evaluate the impact of a three-phase r-ScFCL on the transient stability of a synchronous generator supplying an infinite bus through a step-up transformer and a transmission line. More specifically, the impact of the r-ScFCL design on fault current magnitude, device voltage, temperature, and recovery time was studied. For the chosen case study, the r-ScFCL did increase the stability of the power system. It was also found that parameters such as the length of the superconducting tapes, the number of tapes in parallel, and the shunt resistance can balance or unbalance the response of the r-ScFCL over the three phases during a fault.
Hydrocarbons in silica: PVTX properties of fluids and the genesis of diamond quartz from Caravia-Berbes Fluorite district (Asturias, Spain)
Marine and Petroleum Geology
https://doi.org/10.1016/j.marpetgeo.2018.11.039
Giles Levresse 1 , Jordi Tritlla 2 , Aldo Ramos Rosique 3 , Esteve Cardellach 4 , Claire Rollion Bard 5 , Jacques Pironon 6 , Sergio Jiménez Sandoval 7
1 Universidad Nacional Autónoma de México, Centro de Geociencias
2 Repsol Exploración S. A.
5 Université Paris-Sud, Centre de Recherches Pétrographiques et Géochimiques
6 Université de Lorraine, Geo Ressources
7 Instituto Politécnico Nacional, Centro de Investigación y de Estudios Avanzados

Keywords: Fluid inclusions, PT reconstruction, Hydrocarbon, Diamond quartz, Caravia-Berbes, Spain, Oxygen isotope
Abstract: The fluid history of "diamond? quartz crystals from Caravia-Berbes Fluorite district is intimately related with episodes of maturation and migration of hydrocarbons within the Asturian basin, probably linked to the structural activation of a Mesozoic rift system. These "diamond? quartz record the migration of hydrothermal silica-rich brines and associated hydrocarbons that recorded a temperature increase (outlined by fluid inclusion studies) from ?90 to ?140?°C. This gradient is also recorded by a change in the organic matter species trapped in quartz, from bitumen located in the inner quartz growth zones to liquid hydrocarbons trapped within the outer quartz overgrowths. Secondary ion mass spectrometer (SIMS) oxygen isotope microanalyses allowed to differentiate two Δ18OH2O values corresponding to the oil-dominated zone (core) and the water-dominated zone (outer growth zone). The heavier Δ18OH2O values in the water-dominated zone do not only record a higher temperature of formation, but also an increase in the Δ18OH2O of the parental fluid. Isotopic compositions of diamond quartz suggest a heterogeneous source of surficial fluids and formation-waters expelled from claystones. Within the basin history, the diamond quartz precipitation took place during early Jurassic to Eocene subsidence periods. Pressure Temperature and composition (PTX) and Δ18OH2O characteristics point out a probable relationship with Albian diagenetic events reported in Cantabrian and north Pyrenean basins.
Macro- and micromechanical responses of an elastomeric membrane undergoing biaxial tension by indentation
Journal of Materials Science
https://doi.org/10.1007/s10853-019-03887-w
Itzel Marisol Garnica Palafox 1 , Michelin Álvarez Camacho 2 , Francisco Manuel Sánchez Arévalo 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords:
Abstract: The aim of this work was to develop a methodology and a mechanical tester to determine the macro- and micromechanical behaviours of elastomers under biaxial tension by spherical indentation. Combining the Yang and Begley models, in addition to the experimental data obtained from our mechanical tester, a new methodology to understand the mechanical response of elastomers is presented; this methodology includes elastic modulus, elongation ratios and full-field micro-strain patterns of polymeric membranes undergoing biaxial tension. It was demonstrated that the micro-strain patterns, obtained through 3D digital image correlation, were heterogeneous and higher than those estimated for region contact by numerical models. After an extensive analysis, a general analytical expression that considers the complete set of load versus central displacement experimental data was found to calculate the elastic modulus of elastomers with better accuracy than traditional models. Our device and methodology could become an excellent tool to evaluate the macro- and micromechanical behaviours of soft polymers, cross-linked hydrogels and even biological tissues that exhibit rubber-like mechanical behaviour.
Water use spatio-temporal mapping linked to hydraulic fracturing across the Eagle Ford Play, Texas (USA)
Terra digitalis
http://dx.doi.org/10.22201/igg.25940694.2019.1.59.125
Antonio Hernández Espriú 1 , Saúl Arciniega Esparza 2 , Sergio Macías Medrano 1
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Shale gas, play, water-energy, hydraulic fracturing, Eagle Ford, GIS
Abstract: Massive development of unconventional resources using hydraulic fracturing (HF) procedures, has been carried out since the last three decades, with focus on Texas, USA, including the Eagle Ford (EF) play. International concerns have been raised regarding water and environmental impacts closely related to shale production. The aim of this paper is to map spatio-temporal trends of HF development (water use and well density) examining the entire production period in the EF. We used FracFocus as the main source of HF information, from 2009 to 2017. Our database managed in Python, SAGA GIS and QGIS, comprised 15,013 oil and gas well records. Statistical results show that median HF water use has been progressively increasing over time, from ~18,000 m3/well (2010) to ~38,000 m3/well (2017). Mapping results illustrate that both well density and HF water use peaked in 2014, whereas the area required for HF encompassed ~16,800 km2 or ~70% of the play surface area. We summarize our results in a public domain dynamic GIS-based digital map.
Modeling and simulation to determine the thermal efficiency of a parabolic solartrough collector system
Case Studies in Thermal Engineering
https://doi.org/10.1016/j.csite.2019.100523
Sergio Quezada García 1 , Heriberto Sánchez Mora 1 , Marco A. Polo Labarrios 2 , Ricardo L. Cázares Ramírez 3

Keywords: Solar energyParabolic solar trough collectorNanofluidsHeat transfer in steady stateReduce order mathematical model
Abstract: This study presents a reduced order mathematical model to calculate the heat transfer in steady state in a parabolic trough collector, in which the radial and axial temperature profile of the system is obtained. To solve the model an iterative calculation sequence is used and implemented in Python software, in additional OpenGL is used to generate a schematic visualization of the system. Next, results are validated with data from two different heat-carrier fluids published in the literature, obtaining a maximum relative error less than 10%. The model is used to determine the thermal efficiency using water, thermal oil and nanofluids as heat-carrier fluids. Results show that the thermal efficiency of the parabolic trough collector is higher with nanofluids containing a higher volume fraction of nanoparticles: with a volume fraction of 0.04 and 0.02, the thermal efficiency is of 80% and 79%, respectively. The thermal oil has the lowest efficiency with a maximum efficiency of 76%. The nanofluids allow working at low-pressure levels in the parabolic trough collector compared to pressurized water.
Oil emulsions in naturally fractured porous media
Petroleum
https://doi.org/10.1016/j.petlm.2018.12.004
Ana Paulina Gómora Figueroa 1 , Rodolfo Camacho Velázquez 1 , José Guadarrama Cetina 2 , Iván Guerrero Sarabia 1
2 Universidad de Tarapacá, Instituto de Alta Investigación

Keywords: Oil emulsions, Naturally fractured, Porous media, Heavy and extra-heavy oil, Transportation, Enhanced recovery
Abstract: Most of the studies regarding the formation and stability of emulsions focus on the conditioning and management of crude oil on surface facilities. Since a great deal of the crude oil produced is in the form of stable emulsions, it is often claimed that these emulsions are formed through chokes and other flow constrictions in oil field equipment. However, emulsions are produced in wells, which not only lack these constrictions but also are produced at low flow rates, demonstrating the fact that emulsions can be formed within the well itself. The present work reviews the literature regarding the formation and properties of heavy and extra-heavy oil emulsions in naturally fractured porous media due to the current relevance that these types of crude oil exploitation take, satisfying the hydrocarbon energy demand. Moreover, emulsions have received more attention recently since they can be formed in-situ and improve oil recovery. To understand the flow mechanics of emulsions in porous media, different models to describe their transportation are presented. Finally, the formation of emulsions in the reservoir for enhanced oil recovery purposes, including the use of nanoparticle-stabilized emulsions is discussed.
Partially penetrated well solution of fractal single-porosity naturally fractured reservoirs
Fractal and Fractional
https://doi.org/10.3390/fractalfract3020023
Ricardo Posadas Mondragón 1 , Rodolfo Camacho Velázquez 2
1 Petroleos Mexicanas, Exploración y Producción

Keywords: fractal analytical solution, partially penetrated well, single-porosity, naturally fractured reservoir, well test analysis
Abstract: In the oil industry, many reservoirs produce from partially penetrated wells, either to postpone the arrival of undesirable fluids or to avoid problems during drilling operations. The majority of these reservoirs are heterogeneous and anisotropic, such as naturally fractured reservoirs. The analysis of pressure-transient tests is a very useful method to dynamically characterize both the heterogeneity and anisotropy existing in the reservoir. In this paper, a new analytical solution for a partially penetrated well based on a fractal approach to capture the distribution and connectivity of the fracture network is presented. This solution represents the complexity of the flow lines better than the traditional Euclidean flow models for single-porosity fractured reservoirs, i.e., for a tight matrix. The proposed solution takes into consideration the variations in fracture density throughout the reservoir, which have a direct influence on the porosity, permeability, and the size distribution of the matrix blocks as a result of the fracturing process. This solution generalizes previous solutions to model the pressure-transient behavior of partially penetrated wells as proposed in the technical literature for the classical Euclidean formulation, which considers a uniform distribution of fractures that are fully connected. Several synthetic cases obtained with the proposed solution are shown to illustrate the influence of different variables, including fractal parameters.
Physics-Based Fluid-Flow Modeling of Liquids-Rich Shale Reservoirs Using a 3D Three-Phase Multipososity Numerical-Simulation Model
SPE Reservoir Evaluation & Engineering
https://doi.org/10.2118/191459-PA
Bruno López Jiménez 1 , Roberto Aguilera 2
2 University of Calgary, Schulich School of Engineering

Keywords:
Abstract: Production from liquids-rich shale reservoirs in the US and Canada has increased significantly during the past few years. However, a rigorous understanding of shale rocks and fluid flow through them is still limited and remains a challenge. Thus, the objective of our research is developing a 3D physics-based model for simulating fluid flow through these types of multiporosity rocks. This is important given the recent spread of these types of reservoirs throughout the world. Simulation of liquids-rich shale reservoirs is performed with the construction of an original fully implicit 3D multiphase modified black-oil finite-difference numerical formulation, which uses a multiporosity approach as well as diffusion from solid kerogen. The multiporosity system includes adsorbed porosity, organic porosity, inorganic porosity, natural-fracture porosity, and hydraulic-fracture porosity. A numerical model is developed with capabilities to handle dissolved gas in the solid part of the organic matter, adsorption/desorption from the organic pore walls, viscous- and non-Darcy-flow mechanisms (slip flow and Knudsen diffusion), and stress-dependent properties of natural and hydraulic fractures. Examples of simulated results are presented as crossplots of pressure, production rates, and cumulative production vs. time. These plots are used to show the contributions of free gas, adsorbed gas, and dissolved gas to fluid production from liquids-rich shale reservoirs. Results indicate that both desorption and gas diffusion positively affect shale performance. Simulation results demonstrate that not taking into account desorption and diffusion from solid kerogen leads to underestimating production from liquids-rich shale reservoirs. Furthermore, the simulation study shows that long periods of time are required for the effects of these two mechanisms to be manifested. This helps to explain why shales have been produced over long periods of time (several decades), such as in the case of Devonian wells in the Appalachian Basin. The type of 3D simulation model for multiporosity liquids-rich shale reservoirs developed in this paper is not currently available in the literature. The approach implemented in this paper provides a novel and important foundation for simulating complex shale reservoirs.
Abstraction & Application
Donovan Riaño 1 , Guillermo Molero Castillo 1 , Alejandro Velázquez Mena 1 , Everardo Bárcenas 1

Abstract: This paper presents the use of regular expressions for the treatment of privacy in Web browsers. At present, the use of regular expressions and optical character recognition has been fundamental for multiple Software implementations, solutions in industry topics, robotics, natural language processing, and application development, among others. The test was done in five web browsers. As a result, the detection of advertisements that distract or steal attention was achieved of users. This identification seeks to block advertising on the Web and give user privacy.
Residual stresses and microstructural evolution of ECAPed AA2017
Materials Characterization
https://doi.org/10.1016/j.matchar.2019.04.007
L. Romero Resendiz 1 , I.A. Figueroa 1 , Carlos Reyes Ruiz 2 , José María Cabrera 3 , Chedly Braham 4 , Gonzalo González 1
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
3 Universidad Politécnica de Cataluña, Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica
4 PIMM, Laboratoire Procédés et Ingénierie en Mécanique et Matériaux

Keywords: Al-alloy, ECAP, Texture, Residual stress, Dynamic recovery
Abstract: The mechanical behavior and microstructural evolution of an AA2017 aluminum alloy processed by ECAP with an equivalent simple shear deformation of ?6 at 200?°C were studied. Samples were characterized by means of scanning electron microscopy (SEM-EDS- EBSD), image-assisted by focus ion beam (FIB), Vickers microhardness and X-ray diffraction (XRD) techniques. During the deformation process, the Al2Cu precipitates did not get fragmented or re-absorbed in the Al matrix. After the first ECAP pass, at least 50% of grains displayed an ultrafine size. The EBSD analysis showed an increment of the misorientation angle immediately after the first ECAP pass. The macrotexture evolution was explained in terms of the formation of f1: A1θ??, Aθ, ?θ, A2θ??, f2: Cθ, θ, Bθ, ?θ, Aθ, A1θ?? and f3: Cθ, Bθ, θ, Aθ, ?θ, A2θ?? fibers. The macro-residual stress measurements of the highly deformed samples showed linear sin2? profiles. The micro and macro-residual stresses were compatible with dislocation rearrangement, in which the annihilation and formation were in quasi-equilibrium. It was found that the highest microhardness value (1176?MPa) and grain refinement (at least 20% of grains showed a size smaller than 100?μm2) appeared after the first extrusion pass. The decrease in hardness, after the second pass and the residual stress stability, could be associated to a dynamic recovery phenomenon.
Application of metallurgical slag to treat geothermal wastewater with high concentrations of arsenic and boron
International Journal of Environmental Science and Technology
https://doi.org/10.1007/s13762-018-1952-z
Bertha María Mercado Borrayo 1 , Myriam Solís López 2 , Rafael Schouwenaars Franssens 3 , Rosa María Ramírez Zamora 2
1 Universidad Nacional Autónoma de México, Instituto de Geología
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Agricultural irrigation, chemical precipitation, metals removal, wastewater reuse
Abstract: The reuse of geothermal wastewater for irrigation is an attractive alternative for supplying water demand in agriculture, due to the high volumes generated in geothermal plants. This application is limited by the presence of toxic semimetals such as arsenic and boron, which generally require high-cost commercial adsorbents for removal. This work studies the removal mechanism and process optimization of arsenic and boron, present in high concentrations in synthetic solutions and in geothermal wastewater, using metallurgical slags. The effect of pH, initial concentration of arsenic and boron and slag dose were investigated using a 33 factorial experimental design and response surface method to optimize the operating conditions of the removal of pollutants. Scanning electron microscope analysis showed that the removal mechanism consisted in a dissolution??precipitation reaction rather than adsorption. The effluent produced from wastewater at the optimal operating conditions in a two-step process meets the criteria proposed for both metalloids by the US Environmental Protection Agency for water used for irrigation.
A study of the Taylor-Couette flow with finned surface rotation
Journal of Applied Fluid Mechanics
https://dx.doi.org/10.29252/jafm.12.05.29583
Carlos Álvarez 1 , William Vicente 1 , Francisco Javier Solorio Ordaz 2 , E. Mancilla 3 , Martín Salinas Vázquez 1 , Roberto Zenit 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3
4 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords: Critical rotation rate, Taylor vortex, Annular fins, Taylor-couette flow, Finned rotor, CFD, Vorticity, Micromixing.
Abstract: In this study, the Taylor-Couette flow was disturbed by incorporating annular fins over the inner rotating surface. The finned surface had three parameters: height, width, and length between fins. In this work, seven different fin configurations, in which only the fin height varied, were examined and compared using experimental and numerical techniques. We found that annular fins disturbed the flow behavior by reducing the smooth critical Taylor number (Ta=57.18), but more important, we noticed a vortex enlargement induced by the incorporation of a relatively modest perturbation (b´<0.5) and this change remained in a wider range (0.57
Provenance analysis of Oligocene sandstone from the Cerro Pelón area, southern Gulf of Mexico
International Geology Review
https://doi.org/10.1080/00206814.2018.1476922
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

Keywords: Palaeogene clastic successions, southeastern Mexico, sandstone provenance, Southern Gulf of Mexico
Abstract: In southeastern Mexico, Jurassic and Cretaceous rocks are buried beneath voluminous Palaeogenesedimentary successions, the origin of which is still under debate. Some authors proposed that these Palaeogene successions were derived from Proterozoic, granulite-facies rocks of Oaxaquia, a microcontinental block exhumed during a Late Cretaceous??Palaeogene orogenic event driven by variations in convergence rates along the Pacific margin of North America. Alternatively, other authors suggested that these successions were mostly derived from the Guatemala suture complex, which contains eclogite- to greenschist-facies metamorphic rocks that were exhumed along the Caribbean-North America plate boundary during latest Cretaceous and Palaeogene time. In order to test these scenarios, we present new petrographic data, chemical analysis of detrital heavy minerals, and U-Pb ages of detrital zircons to clarify some aspects on the origin of Oligocene sandstones exposed in the Cerro Pelón area, southeastern Mexico. Our data indicate that the studied sandstones were mostly sourced from eclogite- to greenschist-facies metasedimentary, metaigneous, and ultramafic rocks of the Guatemala suture complex. Minor contributions from the Chiapas Massif Complex exposed directly to the south of the Cerro Pelón area are also documented. Based on these data, we conclude that the accumulation of at least part of the Palaeogene stratigraphic record in southeastern Mexico was mostly controlled by the development of the Caribbean-North America plate boundary rather than by orogenic processes at the Pacific margin of North America.
When is it reasonable to implement the discontinuous sliding-mode controllers instead of the continuous ones? Frequency domain criteria
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.4347
Ulises Pérez Ventura 1 , Leonid Fridman Golredich 1

Keywords: chattering, frequency domain analysis, sliding-mode
Abstract: Professor Utkin proposed an example showing that the amplitude of chattering caused by the presence of parasitic dynamics (stable actuators) in some systems governed by the First?Order Sliding?Mode Controller is lower than that produced by the Super?Twisting Algorithm. This example served to motivate this paper reconsidering the problem of comparison of chattering in systems with stable actuators, and driven by Discontinuous Sliding?Mode Controllers (DSMCs) and Continuous Sliding?Mode Controllers (CSMCs). Comparison of chattering produced by DSMC and CSMC taking into account their amplitudes, frequencies, and average power (AP) needed to maintain the system into real?sliding modes, allowing to conclude the following: (i) for systems with slow actuators, the amplitude of oscillations and AP produced by DSMC be smaller than those caused by CSMC; (ii) for bounded disturbances with fixed Lipschitz constant, there exist sufficiently fast actuators for which the amplitude of oscillations and AP produced by CSMC be smaller than those caused by DSMC.
Energy consumption analysis of ABS plastic parts injected in a hybrid injection moulding machine
International Journal of Sustainable Engineering
https://doi.org/10.1080/19397038.2018.1521881
Javier Ávila Cedillo 1 , Vicente Borja Ramírez 1 , Marcelo López Parra 1 , Alejandro Cuauhtémoc Ramírez Reivich 1

Keywords: Power usage profiles, specific energy consumption, energy behaviour, power consumption, ABS parts, hybrid injection moulding machine
Abstract: The energy analysis of injection moulding processes is influenced by complex interactions amongst the moulded part, its material, the injection machine, the process parameters and the environmental conditions. The availability of energy usage analyses that comprehend information on specific materials and machine kind is limited. This paper reports a study that estimates and analyses the power usage profile (PUP), the specific energy consumption (SEC), and the energy distribution at an operation level of two different injected parts made of acrylonitrile-butadiene-styrene and produced in a hybrid injection moulding machine. The methodology followed by the authors incorporates an experiment carried out in an industrial facility. A large sample size, and data-acquisition and data post-processing processes to obtain an accurate PUP and SEC are used. A breakdown of the energy consumed by the injection moulding process of the parts studied at an operation level using Sankey diagrams is discussed. The study results are used to identify strategies to reduce the energy consumed by the processes. The methodology employed, and the strategies reported could be used with other plastic parts regardless of the material and machine used. The results reported are new experimental data useful input for theoretical models.
Multiple-scale and numerical analyses for the nonlinear oscillations of a gas bubble surrounded by a Maxwell's fluid
International Journal of Fluid Mechanics Research
https://doi.org/10.1615/InterJFluidMechRes.2018024983
César Yepez Terreros 1 , Jorge Luis Naude De la Llave 1 , Federico Méndez Lavielle 1 , Margarita Navarrete Montesinos 2 , Fátima Moumtadi 1
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: bubble dynamics, nonlinear oscillations, Rayleigh equation, multiple-scale analysis
Abstract: In this work, we have revisited theoretically the linear and nonlinear oscillations of a single bubble immersed in a Maxwell's fluid under the action of an acoustic pressure field. We adopt the above rheological model to identify in a simple manner the viscoelastic influence and the impact of the external acoustic field on the motion of the bubble. The governing equations are reduced to a modified Rayleigh??Plesset equation, which is solved together with an ordinary differential equation needed to predict the rheological influence of the normal stresses on the interface of the bubble. The resulting dimensionless governing equations were solved numerically; however, for small deviations from the equilibrium radius of the bubble, we add a frequency analysis by using the multiple-scale method to find the influence of the viscoelastic parameters for those conditions near to resonance, together with the estimation of the bending curve, which characterizes the well-known bending phenomenon. For a single value of the dimensionless Weber number, we have identified that for low Reynolds and Deborah numbers, the oscillations are periodic, with some harmonic ones well defined. However, as we increase the above dimensionless parameters, strong nonlinearities appear, and they are more notable when the effect of the viscous damping is reduced. Furthermore, the effect of the nonlinear terms of the governing equations depends strongly on the amplitudes of the oscillations: when the multiple scale analysis is used and we consider small deviations of the dimensionless equilibrium radius, we obtain that the resonance conditions for the amplitude of the bubble are reduced if the Deborah number is increased. On the other hand, for moderate values of the deviations of the equilibrium radius and retaining the validity of the multiple scale analysis, the foregoing behavior is also conserved. In this last case, stronger amplitudes of the radius of the bubble are obtained also for increasing values of the Deborah number.
Finite frequency H?? control of singularly perturbed Euler?Lagrange systems: An artificial delay approach
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.4383
Jing Xu 1 , Yugang Niu 1 , Emilia Fridman 2 , Leonid Fridman Golredich 3
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

Keywords: artificial time delays, disturbance attenuation, finite frequency, singular perturbations, static output
Abstract: In this paper, we show that small artificial delays in the feedback loops operating in different time scales may stabilize singularly perturbed systems (SPSs). An artificial delay approach is proposed for the robust stabilization and L2-gain analysis of SPSs in the finite frequency domain. A two-time-scale delayed static output feedback controller is designed, in which the controller gains are formulated via a linear matrix inequality (LMI) algorithm. A distinctive feature of the proposed algorithm is setting controller parameters as free variables, which increases the degrees of freedom in controller design and leads to more flexibility in solving LMIs. Moreover, the proposed method is further extended to analyze the finite frequency system specifications of SPSs. The L2-gain performance analysis is conducted for parameter-independent subsystems in their dominant frequency ranges, and the disturbance attenuation level of the original high-order system is then estimated. Finally, the efficiency of the proposed design method is verified in an active suspension system subject to multiple finite frequency disturbance.
Neuroanatomical features and its usefulness in classification of patients with PANDAS
CNS Spectrums
https://doi.org/10.1017/S1092852918001268
Brenda Cabrera 1 , César Romero Rebollar 2 , Luis Jiménez Ángeles 3 , Alma D. Genis Mendoza 1 , Julio Flores 1 , Nuria Lanzagorta 4 , María Arroyo 1 , Camilo De la Fuente Sandoval 5 , Daniel Santana 4 , Verónica Medina Bañuelos 2 , Emilio Sacristán 2 , Humberto Nicolini 1
1 Instituto Nacional de Medicina Genómica, Laboratorio de Psiquiatria Genómica y Desastre Neurodegenerativo
2 Universidad Autónoma Metropolitana, Departamento de Ingeniería Eléctrica
4 Grupo Médico Carracci
5 Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez"""

Keywords: PANDAS, early-onset OCD, gray matter, machine learning, MRI, multivariate pattern analysis, gaussian process classifiers
Abstract: Objective. An obsessive-compulsive disorder (OCD) subtype has been associated with streptococcal infections and is called pediatric autoimmune neuropsychiatric disorders associated with streptococci (PANDAS). The neuroanatomical characterization of subjects with this disorder is crucial for the better understanding of its pathophysiology; also, evaluation of these features as classifiers between patients and controls is relevant to determine potential biomarkers and useful in clinical diagnosis. This was the first multivariate pattern analysis (MVPA) study on an early-onset OCD subtype. Methods. Fourteen pediatric patients with PANDAS were paired with 14 healthy subjects and were scanned to obtain structural magnetic resonance images (MRI). We identified neuroanatomical differences between subjects with PANDAS and healthy controls using voxel-based morphometry, diffusion tensor imaging (DTI), and surface analysis. We investigated the usefulness of these neuroanatomical differences to classify patients with PANDAS using MVPA. Results. The pattern for the gray and white matter was significantly different between subjects with PANDAS and controls. Alterations emerged in the cortex, subcortex, and cerebellum. There were no significant group differences in DTI measures (fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity) or cortical features (thickness, sulci, volume, curvature, and gyrification). The overall accuracy of 75% was achieved using the gray matter features to classify patients with PANDAS and healthy controls. Conclusion. The results of this integrative study allow a better understanding of the neural substrates in this OCD subtype, suggesting that the anatomical gray matter characteristics could have an immune origin that might be helpful in patient classification.
The 19 September 2017 (Mw7.1) Intermediate-Depth Mexican Earthquake: A Slow and Energetically Inefficient Deadly Shock
Geophysical Research Letters
https://doi.org/10.1029/2018GL080904
Aron Mirwald 1 , Víctor M. Cruz Atienza 1 , John Díaz Mojica 1 , Arturo Iglesias 1 , Shri K. Singh 1 , Carlos Villafuerte 1 , Josué Tago Pacheco 2
1 Universidad Nacional Autónoma de México, Instituto de Geofísica

Keywords:
Abstract: We investigate dynamic source parameters of the Mw7.1 Puebla?Morelos intermediate?depth earthquake (h?=?57 km) of 19 September 2017, which devastated Mexico City. Our simple, elliptical source model, coupled with a new Particle Swarm Optimization algorithm, revealed rupture propagation within the subducted Cocos plate, featuring a high stress drop (???=?14.9±5.6 MPa) and a remarkably low radiation efficiency (?r?=?0.16?±?0.09). Fracture energy was large (G?=?(1.04?±?0.3)???1016 J), producing a slow dissipative rupture (Vr/Vs?=?0.34?±?0.04) with scaling?consistent radiated energy (Er?=?(1.8?±?0.9)·1015 J) and energy?moment ratio (Er/M0?=?3.2???10?5). About 84% of the available potential energy for the dynamic rupture was dissipated in the focal region, likely producing friction?induced melts in the fault core of 0.2-1.2 cm width due to heat production (700-1200 °C temperature rise). Such source features seem to be a universal signature of intermediate?depth earthquakes. Plain Language Summary Devastation in central Mexico produced by the intermediate?depth (magnitude 7.1) Puebla?Morelos earthquake of 19 September 2017 has raised important questions about the seismic hazard in Mexico City, where more than 20 million people live. Probabilistic hazard in the city from intermediate?depth and shallower subduction events (i.e., as the 1985 quake that killed 15,000 people in the capital) is about the same despite that the first type of earthquakes is much less frequent. Understanding the source process of intermediate?depth earthquakes has been a major research topic since decades ago because they occur at depths where mechanical considerations for shallow earthquakes are no longer valid. Recent research has led to unexpected conclusions for this kind of events that were thought to be the consequence of fast and energetically efficient rupture processes. Through a novel technique, we investigate the Puebla?Morelos earthquake to better understand the generating physics of the strong ground motions. We show that the event was extraordinarily slow and inefficient and that this does not contradict the large ground accelerations. More than 84% of the earthquake energy was dissipated in the source region likely producing rock melting in the geological fault hosting the rupture process.
Energy production from biogas in a closed landfill: A case study of Prados de la Montaña, Mexico City
Sustainable Energy Technologies and Assessments
https://doi.org/10.1016/j.seta.2018.12.005
Ruth Esther Villanueva Estrada 1 , Roberto Rocha Miller 1 , José Luis Arvizu Fernández 2 , Alejandra Castro González 3
2 Instituto Nacional de Electricidad y Energías Limpias

Keywords: Methane, Mexican model of biogas production, Municipal solid waste landfill, Gas accumulation chamber method, Energetic potentialFugitive emissions
Abstract: The aim of this study was to evaluate the energy potential of the Prados de la Montaña (PM) landfill in Mexico City. The quality of biogas generated by this landfill was monitored in 2013 under passive and forced extraction conditions across 112 extraction wells forming an integrated biogas extraction network. Based on the preliminary results, we can conclude the following: (1) the methane content of biogas produced at the PM landfill was around 45??69%. (2) Forced extraction favored air intrusion through superficial cracks and reduced the methane content of the biogas mixture. (3) Assuming a recovery efficiency of 75%, the biogas flux was estimated at 1081?m3?h-1 (at least 1.8?MW) according to the Mexican model of biogas v. 2.0 for the year 2013. This flux value was less than the value obtained from direct measurement (1505?m3?h-1). A biogas recovery of 908?m3?h-1 is currently estimated, equivalent to 1.5?MW. In conclusion, a good quality and high quantity of biogas is produced at the PM landfill. The characteristics and location of the PM landfill make this landfill an opportune site for biogas production.
Wave reflection by a submerged cycloidal breakwater using the Modified Mild-Slope Equation
Ocean Engineering
https://doi.org/10.1016/j.oceaneng.2019.02.044
M. Barbosa López 1 , Eric Gustavo Bautista Godínez 1 , Federico Méndez Lavielle 2 , S. Bahena Jiménez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Submerged breakwater, Zero-reflection, Coastal engineering, Short waves
Abstract: In this work, formulas for the reflection and transmission coefficients of one-dimensional linear water waves propagating on a submerged structure with a cycloidal cross section are obtained. In the specialized literature, the previous coefficients have been obtained mainly for the limit of linear long water waves, which is a strong restriction for their application. To avoid this restriction, we obtain an approximate analytical solution, based on a Taylor polynomial, to the Modified Mild-Slope Equation, which models the interactions of a wide range of water waves, from short waves to long waves. The dimensionless governing equation is a function of a kinematical parameter and a geometrical parameter. It is found that for a value of 0.35 of the geometrical parameter, the reflection coefficient tends increase significantly. The results show that as the magnitude of the kinematical parameter increases, the reflection coefficient exhibits oscillatory behaviour and increases in magnitude. In addition, for some discrete values of this parameter, the zero-reflection phenomenon occurs. To validate the present approximate analytical solution, we present a comparison against two analytical solutions obtained with the aid of linear long wave theory, in which it is found that three solutions behave properly.
Study of a Cavitating Venturi Tube by Lumped Parameters
Journals of Fluids Engineering
https://doi.org/10.1115/1.4042375
Samuel Cruz 1 , Francisco Antonio Godínez Rojano 2 , Margarita Navarrete Montesinos 2
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: cavitation, void fraction, Venturi tube, lumped parameters, multiphase flow
Abstract: The hydrodynamic cavitation in a Venturi tube is studied both theoretically and experimentally. A lumped parameter model was developed to describe the accumulation and dissipation of energy in the biphasic flow as a function of the bubble population characteristics (mean volume, standard deviation, and void fraction). Resistance, capacitance, inductance, and frequency lumped-parameters were identified applying the fluid conservation equations (mass and momentum) along with electrical/hydraulic analogies. Experiments with 1,2-propanediol were carried out in a hydraulic circuit composed of valves, a pump, and a Venturi nozzle. The acoustic noise generated (at different cavitation regimes) by the passage of the fluid through the tube was acquired with a piezoelectric sensor. After processing the experimental signals, the system frequency at each operation condition was determined. Plausible estimations of the void fraction were obtained at different experimental frequencies by evaluating a theoretical expression of the frequency lumped-parameter. This semi-empirical technique might be a low-cost alternative when the void fraction of a flow needs to be determined and tomography devices are not available.
Effect of noise on the assessment of displacements computed from accelerations recorded at linear and nonlinear civil engineering structures
Measurement
https://doi.org/10.1016/j.measurement.2018.12.108
Jaime De la Colina 1 , Damaris Arias Lara 2 , Jesús Valdés González 1

Keywords: Displacement estimates, Numerical methods, Linear oscillators, Nonlinear oscillators, Earthquake response, Signal noise contamination
Abstract: The purpose of this study is to assess the effect of noise on the estimations of response displacements of single degree-of-freedom systems representative of simple civil-engineering structures subjected to earthquakes. Linear and nonlinear oscillators, with frequencies between 0.1 and 10?Hz and subjected to an earthquake excitation, were considered. Nine signal/noise ratios were studied for two noise input locations: signal contamination at the excitation and signal contamination at the acceleration response. The methodologies considered to estimate displacements were the following: Trifunac and Lee [17], Converse and Brady [9], Chiu [7], and Boore et al. [4]. Results show that noise affects more the estimation of displacements in nonlinear systems than in linear ones. The study also provides values of the signal/noise ratios for which acceptable estimations of displacements are obtained for both linear and nonlinear systems. The most suitable methods to estimate displacements from acceleration records are also recommended.
Crossing VIMP and EIS for studying heterogeneous sets of copper/bronze coins
Journal of Solid State Electrochemistry
https://doi.org/10.1007/s10008-018-04182-5
Francesca Di Turo 1 , Jesús Rafael González Parra 2 , Joan Piquero Cilla 3 , Gabriele Favero 4 , Antonio Doménech Carbó 3
1 Sapienza University of Rome, Department of Earth Sciences
3 Universitat de Valencia, Departamento de Química Analítica
4 Sapienza University of Rome, Department of Chemistry and Drug Technologies

Keywords: Electrochemistry, Archaeology, Electrochemical impedance spectroscopy, Copper, Bronze
Abstract: Electrochemical impedance spectroscopy (EIS) and voltammetry of immobilized particles (VIMP) measurements using air-saturated mineral water and 0.10 M NaClO4 aqueous solution as electrolytes were applied to eurocent coins and a set of copper/bronze coins from the late nineteenth century exhibiting significant heterogeneity in their degree and type of corrosion. The obtained data presented satisfactory repeatability being fitted to relatively simple equivalent circuits which were dependent on the electrolyte and bias potential, the more satisfactory conditions being obtained using the reduction of dissolved oxygen as a redox probe. Consistent data were obtained using VIMP and EIS characterizing different corrosion patterns, and establishing the possibility of discriminating different monetary emissions in favorable cases of high level of corrosion.
Analysis of the use of thorium in the GFR2400 gas-cooled fast reactor
Nuclear Engineering and Design
https://doi.org/10.1016/j.nucengdes.2018.12.016
Yrobel Lima Reinaldo 1 , Juan Luis François Lacouture 1 , Cecilia Martín del Campo 1

Keywords: Gas cooled fast reactors, GFR2400, Thorium, Carbide fuel, Serpent
Abstract: In this work the utilization of thorium in a gas cooled fast reactor was investigated. The study is based on the reference concept proposed by the French CEA (Commisariat à l'Energie Atomique et aux Energies Alternatives), with a thermal power of 2400 MWth (GFR2400). The Monte Carlo Serpent code, version 2.1.29, and the JEFF-3.1 cross section library was used to design a detailed 3D heterogeneous model of the GFR2400 reactor core. The calculations were performed for the reference fuel, uranium plutonium carbide (U, Pu)C and the proposed one, thorium plutonium carbide (Th, Pu)C. The effective multiplication factor for both models was calculated at beginning of life, as well as the neutron spectrum and the neutron flux and power distributions. A safety parameters assessment such as the Doppler constant, the depressurization reactivity effect, the control rods worth and the reactor shutdown margin was also performed. Kinetic parameters such as the effective delayed neutron fraction and the neutron generation time were also determined. The keff variation and the fuel evolution were analyzed for an operation time of 1450 effective full power days. The results show that under a single batch irradiation scheme, the breeding of 233U of our proposed (Th, Pu)C model can be high enough as to enlarge the operating cycle without degradation of the main steady-state neutronic parameters, which remain close to those of the (U, Pu)C reference core.
Linear stability analysis of the natural convection in inclined rotating parallel plates
Physics Letters A
https://doi.org/10.1016/j.physleta.2018.12.014
Diana Perez Espejel 1 , Rubén Ávila Rodríguez 1

Keywords: Stability analysis, Natural convection, Rotating fluids
Abstract: The linear stability analysis of the natural convection in a rectangular tilted infinite cavity filled with a Boussinesq fluid subject to Coriolis force is presented. The bottom and top surfaces have fixed temperatures. Both unstable and stable thermal conditions are studied (heated from below and heated from above respectively). The rotation axis passes through the center and it is orthogonal to the hot and cold surfaces. The stability equations were solved using the Tau??Chebyshev spectral method. The critical Rayleigh number and critical wave number were obtained for several rotation rates and different orientation of convective oblique rolls in a range of inclination of the cavity from 0 to 120 degrees. The stability analysis show that rotation rate affects the basic velocity profile, onset of convection, wave number and critical orientation of convective rolls.
Study of the homogeneous and heterogeneous Am transmutation in an ELFR-like reactor loaded with nitride fuel
Annals of Nuclear Energy
https://doi.org/10.1016/j.anucene.2018.11.052
Luis Carlos Juárez 1 , Juan Luis François Lacouture 2
1 Universidad Nacional Autónoma de México, Instituto de Energías Renovables

Keywords: Americium transmutation, Nitride fuel, European Lead-cooled Fast Reactor, Homogeneous fuel, Heterogeneous fuel
Abstract: In this paper a neutronic study of the homogeneous and heterogeneous core configuration for americium transmutation in an ELFR-like reactor loaded with nitride fuel was performed by using the reactor physics code Serpent. For this, the initial Am content was range as follows: 1, 3, 5, 7 and 9?wt%, and some neutronic and safety parameters, such as the Doppler constant, the coolant void worth and the effective delayed neutron fraction were analyzed. Based on these parameters, the maximum allowable Am content at BoC was 7?wt% for the homogeneous core due to penalties in the coolant void worth. In the heterogeneous core no safety penalties were found but a lowest Am consumption was obtained compared to the homogeneous configuration due to changes in the neutron spectrum. In addition, the axial and the radial power profiles were obtained at three different burnup steps: BoC, MoC and EoC. The homogeneous configuration showed a quite smooth radial and axial power distributions, while an increment in the radial power form factor was observed at the center of the core in the heterogeneous fuel configuration, that deserves further studies.
A re-interpretation of the petrogenesis of Paricutin volcano: Distinguishing crustal contamination from mantle heterogeneity
Chemical Geology
https://doi.org/10.1016/j.chemgeo.2018.10.026
Patricia Larrea 1 , Elisabeth Widom 2 , Claus Siebe 1 , Sergio Salinas 3 , Dave Kuentz 2
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Miami University, Department of Geology & Environmental Earth Science

Keywords: Parícutin, Monogenetic volcanism, Trans-Mexican Volcanic Belt, Subduction zone, Mantle metasomatism
Abstract: Paricutin volcano is the youngest and most studied monogenetic cinder cone in the Michoacán-Guanajuato volcanic field (Mexico), with an excellent historical record of its nine years (February 1943 to March 1952) of eruptive activity. The eruption produced lavas and tephras that range in composition from basalt to andesite. We have conducted new major and trace element and isotopic studies (whole rock Sr-Nd-Pb-Os) of the Paricutin lavas and tephras spanning the entire duration of the eruption, together with xenoliths found in early erupted lavas and bombs, and crustal samples representative of the Paricutin basement. This work contributes to our understanding of the potential roles of mantle source heterogeneity, subduction-related metasomatism, and crustal assimilation in the petrogenesis of arc magmas; moreover this study underscores the complexity of magma generation and evolution in monogenetic volcanoes. Although Paricutin has been traditionally considered as the classical example of magma evolution by fractional crystallization and crustal contamination, our multi-isotopic study has revealed that Paricutin compositional variations are inconsistent with significant crustal assimilation. Alternatively, we suggest that Paricutin's geochemical evolution can be explained by a combination of variable degrees of fractional crystallization of magmas produced by melting heterogeneous mantle beneath the TMVB that has been metasomatized by subduction components including sediment- and oceanic crust-derived fluids.
Methodology and fabrication of adherent and crack-free SU-8 photoresist-derived carbon MEMS on fused silica transparent substrates
Journal of Micromechanics and Microengineering
https://doi.org/10.1088/1361-6439/aaf70f
Oscar Pilloni 1 , Marc Madou 2 , Doroteo Mendoza 3 , Stephen Muhl 3 , Laura Oropeza Ramos 1
2 University of California, Department of Mechanical and Aerospace Engineering
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords: MEMS, microstructure, pyrolysis, carbon, transparent substrate, SU-8
Abstract: Development of carbon based micro electromechanical systems (C-MEMS) has enabled the fabrication of durable, low cost and biocompatible micro devices for specific applications. Thermochemical decomposition of SU-8 (a common photoresist) is often used to fabricate C-MEMS. However, this technique has yielded unreliable results when fabrication on transparent substrates is required due to cracking and detachment of the produced carbon micro structures. We present a methodology for the fabrication of photopatterned carbon films based on SU-8 deposited on transparent fused silica substrates. Specifically, we developed and implemented this methodology for carbon microstructure fabrication derived from SU-8 2035 and SU-8 3035. It was found that SU-8 3035 derived carbon microstructures were crack free and adhered well to the substrate, while SU-8 2035 resulted in fractured and detached carbon microstructures. In addition, we characterized the produced SU-8 3035 derived carbon by measuring its electrical resistivity (1.412????±????0.011 mω m), inter-structure electrical resistance, contact angle (35.7°????±????6.0°), Raman spectrum and adhesion strength to the substrate. In brief, even though SU-8 2035 and SU-8 3035 are useful materials for C-MEMS fabrication, we found that SU-8 3035 is more suitable for the fabrication of crack free and adherent carbon microstructures on transparent fused silica substrates.
Influence of Boron Additions and Heat Treatment on the Fatigue Resistance of CoCrMo Alloys
Materials
https://doi.org/10.3390/ma12071076
Marco Hernández Rodríguez 1 , Rafael Mercado Solis 1 , Gerardo Presbítero 2 , Diego Lozano 3 , Gabriela Martínez Cazares 3 , Yaneth Bedolla Gill 3
1 Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica
3 Universidad de Monterrey, Departamento de Ingeniería

Keywords: CoCrMo, fatigue strength, boron, heat treatment, biomaterial, fatigue crack growth
Abstract: Cobalt-based alloys are widely used in the manufacture of joint prostheses. In this study, the effect of boron additions and heat treatment on the ASTM F75 was evaluated by rotating bending fatigue. The boron ranged from 0.06-1 wt %. The alloys were tested in as-cast and heat-treated conditions. In the as-cast condition, the infinite life was observed at 380 MPa, improving to 433-615 MPa according to the amount of boron added. In the heat treatment condition, the fatigue resistance was improved only in the base alloy. The addition of 0.06 wt % boron and heat treatment led to the same resistance as in the as-cast condition. Adding large amounts of boron combined with heat treatment diminished the fatigue limit. The fracture analysis revealed primarily brittle behaviour with some ductile features even on the same sample, only the heat-treated alloy with 0.06 wt % boron was clearly ductile. This alloy also exhibited notably better toughness to crack propagation.
An experimental study of heat transfer on a tube bank under frost formation conditions
International Journal of Refrigeration
https://doi.org/10.1016/j.ijrefrig.2019.01.031
Hugo Guadalupe Ramírez Hernández 1 , Fausto Sánchez Cruz 1 , Francisco Javier Solorio Ordaz 2 , Simón Martínez Martínez 1
1 Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica

Keywords: Frost formation,Tubes bank, Heat transfer, Frost formation patterns
Abstract: An experimental study of heat and mass transfer on a tube bank under frost formation conditions was conducted using a closed-loop wind tunnel. The tube bank was exposed to a controlled environment; surface temperature from C to C, relative humidity from 50% to 90%, air dry bulb temperature from 1??°C to 11??°C, average air velocity from 0.3 ms to 1.0 ms and Reynolds number from 518 to 1719. The results showed a non-uniform frost growth due to the air stream characteristics. When the Reynolds number increases a more uniform pattern becomes noticeable. The frost growth is more uniform on the last tube than on the first one, due to the aerodynamic differences. Sensible heat transfer has a greater impact on the total heat transfer, compared to latent heat transfer effect. The higher the frost layer growth the lower the frost deposition rate on the tubes.
Induced Polarization and Resistivity of Second Potential Differences (SPD) with Focused Sources Applied To Environmental Problems
Journal of Environmental and Engineering Geophysics
https://doi.org/10.2113/JEEG24.1.49
Aideé López González 1 , Andrés Tejero Andrade 2 , Jejanny Hernández Martínez 3 , Blanca Prado 3 , René E. Chávez Segura 1
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 Universidad Nacional Autónoma de México, Instituto de Geología

Keywords: alkaline earth metals, cadmium clastic sediments, geophysical methods, metals, alkali metals, clay, magnesium, pollution, land use, zinc, sediments, Mexico
Abstract: A novel technique is proposed to improve shallow induced polarization (IP) and resistivity survey results. We propose the apparent resistivity and apparent chargeability of second potential differences (SPD), employing two focused sources (FS) mathematically manipulated by superposition. To test the idea, a synthetic model is developed with two bodies. The first body is a small shallow heterogeneity which is above the second and larger body. This synthetic model illustrates the shape and response of the apparent resistivity and chargeability for FS under the random noise and masking effect. These processes reduce electromagnetic coupling, telluric noise, contamination in channel links, and small heterogeneous responses. A field test of the SPD for FS was carried out in an agricultural site irrigated with wastewater, where contaminated water laden with metals has been accumulating for years in the soil. Soil samples were collected and analyzed throughout the geophysical survey to correlate the resistivity-IP results. Soil laboratory analysis included metal content, moisture content and texture. The parameters computed after applying the SPD for FS depicted a better lateral resolution where vertical and horizontal boundaries of the anomaly zones were well defined. It was possible to determine the low permeability horizontal layer made of clay-soil (called tepetate), which is a barrier for water and metals.
Large-amplitude oscillatory shear flow simulation for a FENE fluid
Rheologica Acta
https://doi.org/10.1007/s00397-019-01145-z
Aldo Gómez López 1 , Víctor Ferrer 2 , Eduardo Rincón 3 , Juan Pablo Aguayo Vallejo 4 , Ángel Chávez 5 , René Vargas 6
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 Sociedad al Servicio de la niñez S.C., Dirección Morelos
4 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
6 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica, Azcapotzalco

Keywords: LAOS, Multiscale, Maximum extension length, Oscillatory flow, Viscoelasticity, FENE model
Abstract: In this work, the FENE dumbbell model under small- and large-amplitude oscillatory shear flows using a micro-macro approach is presented. This approach involves the evolution of an ensemble of Brownian Configuration Fields which describes the polymer dynamics of the microscopic scale and the momentum equation describes the macroscopic scale. The Lissajous curves for the shear stress and the first normal stress difference versus the instantaneous strain or strain rate for the elastic or viscous projection are shown. The influences of the solvent/polymer viscosity ratio, the maximum extension length, and the relation between strain rate and frequency are analyzed. An important finding is the self-intersection of the Lissajous curves, which forms secondary loops for short extension lengths and high Weissenberg/Deborah dimensionless numbers ratio.
High-order sliding-mode observer-based input-output linearization
International Journal of Robust and Nonlinear Control
https://doi.org/10.1002/rnc.4556
Alejandra Ferreira De Loza 1 , Leonid Fridman Golredich 2 , Luis T. Aguilar 1 , Rafael Iriarte 2
1 Instituto Politécnico Nacional, Centro de Investigación y Desarrollo de Tecnología Digital

Keywords: disturbance identification, robust nonlinear control, sliding-mode control, uncertain systems
Abstract: The problem of output control in multiple?input??multiple?output nonlinear systems is addressed. A high?order sliding?mode observer is used to estimate the states of the system and identify the discrepancy between the nominal model and the real plant. The exact and finite?time estimation may be tackled as long as the system presents the algebraic strong observability property. Thus, a continuous robust input?output linearization strategy can be obtained with respect to a prescribed output. As a consequence, the closed?loop dynamics performs robustly to uncertainties/perturbations. To illustrate the advantages of the proposed method, we introduce a study case that demands a robust linear system behavior: the self?oscillations induced in an underactuated mechanical system through a two?relay controller. Experiments with an inertial wheel pendulum illustrate the feasibility of the proposed approach.
Comparative study of the neutronic performance of thorium-based metallicfuel and MOX fuel in an ASTRID-like fast reactor core
Nuclear Engineering and Design
https://doi.org/10.1016/j.nucengdes.2019.03.027
Daniel Escorcia Ortiz 1 , Juan Luis François Lacouture 1 , Cecilia Martín del Campo 1

Keywords: ASTRIDThoriumSodium fast reactorsBreedingMetallic fuel
Abstract: As the continuation of a previous research work, in this paper the utilization of thorium-based metallic fuel is investigated in an ASTRID-like fast reactor core. The main goal of this paper is to compare the neutronic behavior and the isotopes evolution between the previously studied reference core, based on oxide fuel, and a core loaded with metallic thorium-based fuel for the same ASTRID-like reactor. The reference core, in which the fuel is a material composed of a mixture of U-Pu MOX, was compared with an equivalent core with a U-Pu-Zr metallic alloy fuel (Met-UP) and two alternative thorium-fueled strategies. For the first strategy, a combination of 232Th/233U was introduced in the fertile zone instead of the uranium isotopes, keeping the fissile zone composition unchanged (Met-UPT). For the second strategy, the fertile zone was kept with the same composition as in the first strategy, while a mix of 232Th/233U replaced the fissile fuel zone composition (Met-UT). The calculations were made with the Monte Carlo MCNP6 code and the ENDF/B-VII.0 cross section library. The parameters analyzed were: the neutron multiplication factor for a burnup of one year, the neutron energy spectrum, the Doppler effect, the coolant density reactivity effect, the delayed neutrons fraction and the control rods reactivity worth (shutdown margin). The radial power distribution and the concentration evolution of the main isotopes for each fueling strategy in the core were also analyzed. The main findings of this study were: the effective neutron multiplication factor of the reference core and that of the Met-UPT case is very close, meanwhile, the configuration Met-UT has an important loss of reactivity along the burnup. Regarding the neutron energy spectrum, it becomes harder with a higher thorium fraction in the core. Related to the fissile isotopes, in the reference core 239Pu is produced, meanwhile, 233U is bred in the fertile zone of the configuration with 232Th/233U. The Am and Cm actinides production are lower for the 232Th/233U in the fertile zone compared to the reference configuration and null in the case of the full core with 232Th/233U. Doppler constants have negative values and show similar behavior in all the core configurations. Regarding the coolant density reactivity effect, the metallic fuel configuration with 232Th/233U in the full core shows the better behavior. The power distribution is similar in all the cases, showing a region with the highest power in the outer fuel zone. The metallic fuel configurations have higher power peaks. The full 232Th/233U fuel configuration has the flattest power distribution and the lower effective delayed neutrons fraction. All core configurations show a very good shutdown margin, widely greater than 1000?pcm at the beginning of the cycle. As a result of this study, it can be concluded that the Met-UP configuration can be considered as the best option followed by the Met-UPT configuration.
Algoritmo para analizar decisiones con objetivos múltiples bajo incertidumbre
Ingeniería Investigación y Tecnología
http://dx.doi.org/10.22201/fi.25940732e.2019.20n1.010
José Jesús Acosta Flores 1

Keywords: Decisiones, objetivos múltiples, incertidumbre, funciones utilidad, equivalentes bajo certeza, criterios de dominancia, permutas compensatorias
Distribución espacial de variables hidrológicas. Implementación y evaluación de métodos de interpolación
Ingeniería Investigación y Tecnología
http://dx.doi.org/10.22201/fi.25940732e.2019.20n2.023
José Luis Aragón Hernández 1 , Germán Adrián Aguilar Martínez 2 , Ulises Velázquez Ríos 1 , Martín Rubén Jiménez Magaña 3 , Alejandro Maya Franco 1
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Precipitación media, distribución espacial, métodos de interpolación, correlación cruzada, variograma
Computer Algorithm for Archaeological Projectile Points Automatic Classification
Journal on Computing and Cultural Heritage
https://doi.org/10.1145/3300972
Fernando Castillo Flores 1 , Francisco Javier García Ugalde 1 , José Luis Punzo Díaz 2 , Jesús Zarco Navarro 3 , Alfonso Gastelum Strozzi 4 , María del Pilar Angeles 1 , Mariko Nakano Miyatake 5
2 Instituto Nacional de Antropología e Historia, Arqueología
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones Antropológicas
4 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
5 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación

Keywords: Projectile points, automatic classification, pattern recognition, image analysis, computervision, CSS-map, lithic technology
Abstract: The manual archaeological projectile point morphological classification is an extensive and complex process since it involves a large number of categories. This article presents an algorithm that automatically makes this process, based on the projectile point digital image and using a classification scheme according to global archaeological approaches. The algorithm supports different conditions such as changes in scale and quality of the image. Moreover, it requires only a uniform background and an approximate north--south projectile point orientation. The principal computer methods that compose the algorithm are the curvature scale space map (CSS-map), the gradient contour on the projectile point, and the support vector machines (SVM) algorithm. Finally, the classifier was trained and tested on a dataset of approximately 800 projectile points images, and the results have shown a better performance than other shape descriptors such as Pyramid of Histograms of Orientation Gradients (PHOG), Histogram of Orientation Shape Context (HOOSC) (both used in a bag-of-words context), and geometric moment invariants (Hu moments).
Power control of a doubly fed induction generator connected to the power grid
International Journal of Control
https://doi.org/10.1080/00207179.2017.1397752
Irvin López García 1 , Gerardo Espinosa Pérez 2 , V. Cárdenas 3
3 Universidad Autónoma de San Luis Potosí, Centro de Investigación y Estudios de Posgrado

Keywords: Passivity-based control, doubly fed induction generator, wind turbine, active power, reactive power
Abstract: In this paper, the regulation control problem of the active and reactive power at the common connection point between a doubly fed induction generator and the grid is approached. The proposed controller is developed exploiting the passivity properties of the considered model for the control system. It is considered the existence of a wind turbine that delivers a time-varying torque to the generation unit which exhibits a highly nonlinear structure due to the variations of the wind speed. From a theoretical perspective, the main feature of the contribution lies in the fact that it is formally proved that the equilibrium point of the closed-loop system that corresponds to the desired power exhibits practical global asymptotic stability properties. This characteristic is obtained applying well-known theory from the perturbed nonlinear dynamical systems theory. However, in the numerical evaluation of the proposed controller, it is illustrated how these properties are indeed stronger since asymptotic stability is achieved.
Numerical investigation on buoyancy and inclination effects on transient mixed convection in a channel with discretely heated plane symmetric contraction-expansions
International Journal of Thermal Sciences
https://doi.org/10.1016/j.ijthermalsci.2019.106056
Felipe Rolando Menchaca García 1 , César Treviño 2 , Erick Salcedo 3 , Lorenzo Martínez Suástegui 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica

Keywords: Mixed convectionForward-backward facing stepSeparation and reattachment flowOscillatory fluid motionPartially blocked geometriesWall effects
Abstract: In this work, transient mixed convection in a channel with discretely heated plane symmetric contraction-expansions at the mid-channel section emulating electronic components is studied numerically. The facing walls of the obstructions are isothermal, the other bounding walls of the constriction and the channel have non-adiabatic walls. The impact of changes in the cross section and their corresponding sensitivity to duct orientation on the overall flow and thermal evolution in space and time is analysed for fixed Prandtl number of , Reynolds number in the range 100 1000, channel inclination of , and different values of buoyancy strength (Richardson number). Results indicate that as the duct approaches the horizontal configuration, buoyancy strength reduces and higher threshold values of the Richardson number are required to induce instability. Also, depending on the parametric set, the flow and temperature distributions can experience an oscillatory behavior associated to variations in size of a complex vortical structure that occupies the spatial region near the partial blockage and that extends to downstream positions of the latter. Numerical predictions demonstrate how the blockage height affects the wake structure and vortex dynamics, and the effects of the Prandtl number and heat losses to the channel walls on the evolution of the flow and heat transfer response are presented and discussed in detail.
Algorithm to calculate suspended sediment concentration using landsat 8 imagery
Applied Ecology and Environmental Research
http://dx.doi.org/10.15666/aeer/1703_65496562
Griselda Berenice Hernández Cruz 1 , M. Vázquez Ortiz 2 , Carlos Canet Miquel 3 , Jorge Prado Molina 4
2 Secretaría de Agricultura, Instituto Nacional de Pesca y Acuacultura
3 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
4 Universidad Nacional Autónoma de México, Laboratorio Nacional de Observación de la Tierra

Keywords: Grijalva River, spectral response, sediments decrease, particles size, speedtech sounder
Abstract: Satellite imagery was used to assess the suspended sediment concentration (SSC) of the plume at the Grijalva river mouth, Gulf of Mexico. The SSC was calculated with the algorithm of Topliss. The algorithm was created for Lansdast 5 MSS. For this study it was validated the results for Landsat 7 ETM+ and Landsat 8 OLI. The depth of the ocean floor was measured using the speedtech sounder. The spectral response was registered with a GER-1500 spectroradiometer (with a measurement range of 296.71??1092.08 nm). The spectral responses were used to determine the size of the suspended particles and to perform the atmospheric correction. Spectral responses indicate that silt size particles predominate near the river mouth, whereas clay overtakes further towards the open sea. The trend in the river when water meets seawater, means an increase of suspended sediment towards the surface due to the lower density of fresh water, and the amount of sediment rises in the open sea. The correlation between the measurements in situ and SSC values produced by the algorithm demonstrates that the operation is suitable to estimate suspended sediments.
Automatic Speech Recognizers for Mexican Spanish and its Open Resources
Journal of Applied Research and Technology
https://doi.org/10.1016/j.jart.2017.02.001
Carlos Daniel Hernandez Mena 1 , Iván Meza Ruiz 2 , Abel Herrera Camacho 1
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas

Keywords: Automatic speech recognition, Mexican Spanish, Language resources, Language model, Acoustic model
Abstract: Development of automatic speech recognition systems relies on the availability of distinct language resources such as speech recordings, pronunciation dictionaries, and language models. These resources are scarce for the Mexican Spanish dialect. In this work, we present a revision of the CIEMPIESS corpus that is a resource for spontaneous speech recognition in Mexican Spanish of Central Mexico. It consists of 17 h of segmented and transcribed recordings, a phonetic dictionary composed by 53,169 unique words, and a language model composed by 1,505,491 words extracted from 2489 university newsletters. We also evaluate the CIEMPIESS corpus using three well known state of the art speech recognition engines, having satisfactory results. These resources are open for research and development in the field. Additionally, we present the methodology and the tools used to facilitate the creation of these resources which can be easily adapted to other variants of Spanish, or even other languages.
Application of Different Statistical Tests to Validate Synthesized Speech Parameterized by Cepstral Coefficients and LSP
Computación y Sistemas
https://doi.org/10.13053/CyS-23-2-2977
Carlos Franco Galván 1 , Abel Herrera Camacho 2 , Boris Escalante Ramírez 2
1 Benemérita Universidad Autónoma de Puebla

Keywords: Speech synthesis, voice parameterization, line spectral pair.
Abstract: The following document tries out different statistical norms to validate the quality of synthesized voices applied to an HTS-based Spanish synthesizer, which uses LSP and Cepstral Coefficients parameterizations. Standard MOS tests were carried out. Nevertheless, other types of quality tests were performed to reinforce the MOS results. Such as: MUSHRA, ABX and CCR. The subjective test PESQ was also applied. To validate intelligibility a SUS test was used.
Sequential indicator simulation for a three-dimensional distribution of hydrofacies in a volcano-sedimentary aquifer in Mexico City
Hydrogeology Journal
https://doi.org/10.1007/s10040-019-02011-1
Priscila Medina Ortega 1 , Eric Morales Casique 2 , Antonio Hernández Espriú 1
2 Universidad Nacional Autónoma de México, Instituto de Geología

Keywords: Indicator geostatistics, Hydrofacies, Aquifer heterogeneity, Lithological logs, Mexico
Abstract: The Mexico City aquifer is a complex mix of alluvial deposits and volcanic rocks overlapped by an aquitard composed of lacustrine deposits. To characterize this heterogeneous hydrogeologic system, a three-dimensional model of the distribution of hydrofacies is constructed using borehole lithological records. The analysis is based on 111 borehole logs with an average depth of 300 m, in an area of 234 km2, providing a nominal scale of resolution of 2.1 km in the plane and 2-m resolution in the vertical direction. These records were discretized to generate a georeferenced dataset of 13,518 points associated with a lithological category; nine lithological categories were observed. These categories were subsequently grouped into four hydrofacies: A and B, grouping low-permeability lithological categories (lacustrine and volcano-sedimentary materials, respectively); and C and D, grouping high-permeability lithological categories (volcanic rocks and alluvial deposits, respectively). The database was analyzed in terms of proportion of hydrofacies at depth, distribution of layer thickness, and behavior of experimental horizontal and vertical variograms. The experimental variograms of each hydrofacies were fitted to exponential models via minimization of cross-validation errors. Three-dimensional models of probability of occurrence of each hydrofacies and the combined distribution of hydrofacies were then constructed via ensemble averaging of 1,000 realizations obtained by sequential indicator simulation. The potential use of this model for water management, modeling land subsidence, and groundwater pollution is discussed.
Life Cycle Assessment of a Combined-Cycle Gas Turbine with a Focus on the Chemicals Used in Water Conditioning
Sustainability
https://doi.org/10.3390/su11102912
Catalina Ferat Toscano 1 , Cecilia Martín del Campo 1 , Gabriela Moeller Chavez 2 , Gabriel León De los Santos 1 , Juan Luis François Lacouture 1 , Daniel Revollo Fernández 3
2 Universidad Politécnica del Estado de Morelos, Dirección de Ingeniería Ambiental y Biotecnología

Keywords: water quality, life cycle assessment, emerging pollutants, combined-cycle gas turbine, chemical compounds, hydrazine, electric power generation
Abstract: Life Cycle Assessments (LCAs) of thermoelectric plants frequently focus on impacts related to fuel and water consumption. The purpose of this research was to determine the environmental impact of the chemicals used for water conditioning in a Combined-Cycle Gas Turbine (CCGT) plant in Mexico. An LCA of the electricity generation process was carried out using the SimaPro software with the ReCiPe method, which includes 18 midpoint environmental impact categories. The process was broken down into stages, which were analyzed separately. To complete the study, an analysis of the fuel cycle and the materials used for maintenance works were included. Results showed that the most affected impact categories were water depletion (9.77 ? 10??1 m3/MWh), due mainly to the high volume of water consumption in the cooling systems and the reverse osmosis process; freshwater, marine, and terrestrial ecotoxicity (1.59 ? 10??2 kg 1,4 -DB eq/MWh), and human toxicity (1.1 ? 10??1 kg 1,4-DB eq/MWh)??due to the production and consumption of the chemicals used. One such chemical is hydrazine, which is a highly toxic compound to humans and other living organisms. It is worth mentioning that traces of some chemicals in wastewater discharges could be considered as emerging pollutants because of their potential health hazards, which have not been reported yet.
An Active Vehicle Suspension Control Approach with Electromagnetic and Hydraulic Actuators
Actuators
https://doi.org/10.3390/act8020035
Francisco Beltran Carbajal 1 , Antonio Valderrabano González 2 , Antonio Favela Contreras 3 , José Luis Hernández Ávila 1 , Irvin López García 1 , Rubén Tapia Olvera 4
3 Tecnológico de Monterrey

Keywords: active vibration control, vehicle suspension, signal differentiation, disturbance reconstruction
Abstract: An active vibration control approach from an online estimation perspective of unavailable feedback signals for a quarter-vehicle suspension system is introduced. The application of a new signal differentiation technique for the online estimation of disturbance trajectories due to irregular road surfaces and velocity state variables is described. It is assumed that position measurements are only available for active disturbance suppression control implementation. Real-time signal differentiation is independent of detailed mathematical models of specific dynamic systems and control force generation mechanisms. Active control forces can be supplied by electromagnetic or hydraulic actuators. Analytical and simulation results prove the effective and fast dynamic performance of the online signal estimation as well as a satisfactory active disturbance attenuation on a quarter-vehicle active suspension system.
Combined viscoelectric and steric effects on the electroosmotic flow in a microchannel under induced high zeta potentials
Colloids and Surfaces A: Physicochemical and Engineering Aspects
https://doi.org/10.1016/j.colsurfa.2019.05.050
Edson M. Jiménez 1 , Juan P. Escandón Colín 2 , Federico Méndez Lavielle 1 , Oscar Eladio Bautista Godínez 2
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Electroosmotic flow, Viscoelectric effect, Steric effect, Heterogeneous zeta potentials, Nanochannel, Microchannel
Abstract: The present study analyzes the combined viscoelectric and steric effects on the electroosmotic flow of Newtonian fluids in nano/microchannels. The governing equations that describe the flow field are the modified Poisson-Boltzmann equation for the electric potential, the mass conservation and momentum equations, which are solved numerically. On the channel walls, arbitrary and heterogeneous zeta potentials modulated via sinusoidal functions are imposed, being controlled by a phase angle, an amplitude and a wave number. The use of arbitrary zeta potentials leads to the study of the viscoelectric effect due to the fact that the viscosity near the walls of the channel increases drastically. Also, the presence of high ionic concentrations and large effective ionic sizes causes an excluded volume of the crowding of ions into the electric double layer; in this manner, the study of the steric effect is relevant in the present work. The results show that the viscoelectric effect produces a reduction in the magnitude of the velocity profiles when zeta potentials are magnified. On the contrary, the steric effect counteracts the aforementioned effect, increasing the velocity of the flow. In addition, the heterogeneous zeta potentials at the walls generate an induced pressure and recirculations on the flow. In particular, when the wave number is even leads to a condition with null volumetric flow rate; while for an odd wave number, a favorable volumetric flow rate is generated. This study extends the knowledge of electroosmotic flows under field effects for future mixing applications.
Metallurgical Wastes Employed as Catalysts and Photocatalysts for Water Treatment A Review
Sustainability
https://doi.org/10.3390/su11092470
Claudia Victoria Montoya Bautista 1 , Edwin Avella 1 , Rosa María Ramírez Zamora 1 , Rafael Schouwenaars Franssens 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: metallurgical wastes, slag, low-cost catalyst, water treatment, hydrogen production, valorization
Abstract: Metallurgical slags are a mass-produced industrial solid waste, often destined to landfills; the volumes disposed represent an environmental burden. Over the last three decades, applications have been found for these wastes, mainly as a low-cost additive in building materials. More recently, their unique chemical properties have attracted attention to produce high-added-value materials for environmental applications, to be used as adsorbents, catalysts, or a source of reactive species in environmental engineering. Such uses can be classified as a function of the added value generated, technological complexity, and environmental impact. This review will focus specifically on the modification and use of slags for catalysis, photocatalysis, and photocatalytic production of hydrogen, which have received relatively little attention in literature. A summary will be presented about the general requirements for using unmodified slags as well as slag processed under alkaline or acidic conditions for advanced oxidation processes. Then, an overview will be given of the use of slags as photocatalysts in water treatment, organized according to the origin of the product (steel, copper, magnesium, ferromanganese), as well as emerging reports on the photocatalytic production of hydrogen, in contrast to the use of highly specific titania-based products developed for the same purpose.
Nanocrystalline and Silicon Steel Medium-Frequency Transformers Applied to DC-DC Converters: Analysis and Experimental Comparison
Energies
https://doi.org/10.3390/en12112062
Dante Ruiz Robles 1 , Jorge Ortíz Marín 1 , Vicente Venegas Rebollar 1 , Edgar Lenimirko Moreno Goytia 1 , David Granados Lieberman 2 , Juan Ramón Rodríguez Rodríguez 3
1 Instituto Tecnológico de Morelia, División de Estudios de Posgrado e Investigación
2 Instituto Tecnológico Superior de Irapuato, Posgrado de Ingeniería Eléctrica

Keywords: converter DC-DC, medium frequency transformer, renewable energies, solid state transformers, electric vehicles
Abstract: High performance, highly efficient DC-DC converters play a key role in improving the penetration of renewable energy sources in the context of smart grids in applications such as solid-state transformers, built-in power drives in electric vehicles and interfacing photovoltaic and wind-power systems. Advanced medium-frequency transformers (MFTs) are fundamental to enhance DC-DC converters and determining its behavior, therefore MFT design procedures have become increasingly important in this context. This paper investigates which type of core material, between nanocrystalline and silicon steel, has the best properties for designing MFTs for distinct applications. Unlike to other proposals, in this work, two 1 kVA-120 V/240 V-1 kHz lab MFT prototypes, with a different type of core material, are developed for the purpose of comparing its physical characteristics, behavior, and performance under real-life conditions. A final section, the experimental results show that the nanocrystalline MFT has greater power density and efficiency. The results of this work introduce nanocrystalline MFTs as an option in a wider range of applications in niches in which other materials are currently used.
Evaluando los contratos de exploración y extracción de hidrocarburos en México, 2015-2017
Problemas del Desarrollo. Revista Latinoamericana de Economía
https://doi.org/10.22201/iiec.20078951e.2019.197.64669

Keywords: contratos de exploración, contratos de producción, hidrocarburos, rondas de licitaciones, renta petrolera
Abstract: Se estima el reparto de la renta petrolera y el volumen de producción entre el Estado y el contratista, de acuerdo con lo establecido en los contratos adjudicados. Primero se describen las modalidades contractuales, el régimen fiscal y el mecanismo de licitación; luego se analiza el reparto físico y económico de la producción. Se concluye que el Estado recibe en promedio 72.4% de la renta cuando el contratista es eficiente, frente a un 56.5% cuando es ineficiente. En las licencias, el Estado no recibe producción alguna y, en los contratos de producción compartida recupera 30%, en un escenario de costos ineficientes.
A Preliminary comparative study between oxide and metallic fuelled ASTRID-like reactor under a B&B strategy
International Journal of Nuclear Energy Science and Technology
https://dx.doi.org/10.1504/IJNEST.2019.099692
Juan Luis François Lacouture 1 , Elías Yammir García Cervantes 1 , Cecilia Martín del Campo 1

Keywords: fast reactors, sodium-cooled reactor, breed and burn, metallic fuel, ASTRID.
Abstract: The objective of this paper is to study the reactivity behaviour and the isotopic fuel performance of an ASTRID-like reactor under a breed and burn strategy for two core designs: with oxide and with metallic fuel. The proposed reshuffling scheme was simulated with MCNP6 and the JEFF-3.2 cross-sections library to extend the fuel life by two more cycles. Our findings showed that the implementation of the reshuffling scheme enhanced the fuel utilisation, obtaining cycle extensions of 805 days and 1305 days, over the first 365 days, for the oxide and metallic fuelled designs, respectively. For the metallic-fuelled design the breeding of Pu-239 achieved a production of 577.7 kg, which represents a production rate of 126.3 kg/EFPY. The conversion rate for the metallic-fuelled design was 1.06 and 0.96 for the oxide-fuelled design. Regarding the coolant void reactivity worth, for the oxide-fuelled design it becomes positive after the second fuel reshuffling.
Photocatalytic H2 Production and Carbon Dioxide Capture Using Metallurgical Slag and Slag Derived Materials
Handbook of Ecomaterials
https://doi.org/10.1007/978-3-319-68255-6_117
Claudia Victoria Montoya Bautista 1 , Brenda Cecilia Alcántar Vázquez 1 , Myriam Solís López 1 , C. G. Tabla Vázquez 1 , A. A. Morales Pérez 2 , Rafael Schouwenaars Franssens 3 , Rosa María Ramírez Zamora 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords:
Abstract: Consumption of fossil fuels increases year by year with negative impacts on the environment, particularly due to the emission of carbon dioxide (CO2), a major anthropogenic greenhouse gas. Consequently, important scientific challenges for the upcoming years are the development of cleaner energy sources to satisfy the increasing energy demand, the reduction of the consumption of fossil fuels, and mitigation of the CO2 emissions. Therefore, the production of renewable fuels with high energy content is researched, while efficient CO2 capture is developed to reduce emissions from less-clean energy resources. For the former challenge, the production of hydrogen by heterogeneous photocatalysis is a potential solution. For the second problem, the use of solid sorbents for CO2 capture as CaO and alkaline ceramics are promising proposals. The development of catalysts and materials for CO2 capture with high efficiency and stability as well as reasonable production costs is a great challenge. In the search for new efficient and inexpensive materials, metallurgical slags are quite attractive due to their physicochemical characteristics, abundance, and low cost. The high iron oxide content (>50% w/w) and the presence of crystalline phases such as fayalite (Fe2SiO4) and magnetite (Fe3O4) in the metallurgical copper slag indicate it may be active photocatalyst. On the other hand, the composition of the iron and steel slags makes these materials an excellent feedstock for the synthesis of CaO-based materials and other derived materials for CO2 capture technologies.
Stability Analysis of Single-Phase Low-Voltage AC Microgrids With Constant Power Terminals
IEEE Transactions on Circuits and Systems - II: Express Briefs
https://doi.org/10.1109/TCSII.2018.2878188
Oscar Danilo Montoya Giraldo 1 , Alejandro Garces 2 , Sofía Ávila Becerril 3 , Gerardo Espinosa Pérez 3 , F. M. Serra 4
4 Universidad Nacional de San Luis, Automation Control Laboratory

Keywords: Load modeling, Power system stability, Microgrids, Mathematical model, Circuit stability, Stability criteria
Abstract: This express brief presents the stability analysis of single-phase microgrids (SP-MG) operating under master-slave connection with constant power terminals. The SP-MG is composed of linear elements, nonlinear loads, and distributed generators modeled as PQ constant terminals interconnected through power electronic converters. Lyapunov's direct method through a Hamiltonian representation of the grid is used to demonstrate stability. The non-autonomous model of the SP-MG is transformed into an autonomous equivalent model based on the dynamics of the error. The proposed analysis shows that if there is an admissible trajectory x* solution of the power flow equations, then the SP-MG is stable in the sense of Lyapunov.
Transparent bilateral teleoperation interacting with unknown remote surfaces with a force/velocity observer design
Internation Journal of Control
https://doi.org/10.1080/00207179.2017.1371338
Alejandro Gutiérrez Giles 1 , Marco Antonio Arteaga Pérez 2
1 University of Naples Federico II, CREATE Consortium and Prisma Laboratory

Keywords: Transparent bilateral teleoperation, force control, observer design, unknown environment
Abstract: A master??slave teleoperation system is considered, in which the slave manipulator is interacting with a rigid surface with unknown geometry. It is assumed that neither force nor velocity measurements at the slave side are available. To deal with this problem, an extended-state high-gain observer is proposed to estimate in an arbitrary close manner the velocity and force signals. At the same time, the gradient vector for the remote surface is online estimated and employed into an hybrid position/force controller based on the orthogonal decomposition of the task space. A formal proof is presented, which guarantees ultimate boundedness of the state of the system, with arbitrarily small ultimate bound. Furthermore, it is established the transparency of the teleoperation system that, roughly speaking, gives the human operator the sensation of being interacting directly with the remote surface. The proposed scheme is validated through numerical simulations and experiments.
THD Reduction in Distributed Renewables Energy Access through Wind Energy Conversion System Integration under Wind Speed Conditions in Tamaulipas, Mexico
Energies
https://doi.org/10.3390/en12183550
Nadia Maria Salgado Herrera 1 , David Campos Gaona 2 , Olimpo Anaya Lara 3 , Juan Ramón Rodríguez Rodríguez 4
1 Universidad Nacional Autónoma de México (UNAM), Instituto de Energías Renovables
2 University Of Strathclyde
3 University Of Strathclyde , Institute for Energy and Environment

Keywords: wind farm control, wind energy conversion systems, reactive power control, THD, type-4 wind turbine
Abstract: In this article, a technique for the reduction of total harmonic distortion (THD) in distributed renewables energy access (DREA) composed of wind turbines is introduced and tested under the wind speed conditions presented in Tamaulipas, Mexico. The analysis and simulation are delimited by a study case based on wind speeds measured and recorded for one year at two highs in the municipality of Soto La Marina, Tamaulipas, Mexico. From this information, the most probable wind speed and the corresponding turbulence intensity is calculated and applied to a wind energy conversion system (WECS). The WECS is composed of an active front-end (AFE) converter topology using four voltage source converters (VSCs) connected in parallel with a different phase shift angle at the digital sinusoidal pulse width modulation (DSPWM) signals of each VSC. The WECS is formed by the connection of five type-4 wind turbines (WTs). The effectiveness and robustness of the DREA integration are reviewed in the light of a complete mathematical model and corroborated by the simulation results in Matlab-Simulink®. The results evidence a reduction of the THD in grid currents up to four times and which enables the delivery of a power capacity of 10 MVA in the Tamaulipas AC distribution grid that complies with grid code of harmonic distortion production.
Monitoring of Sobradinho landslide (Brasília, Brazil) and a prototype vertical slope by time-lapse interferometry
Brazilian Journal of Geology
http://dx.doi.org/10.1590/2317-4889201920180085
Yawar Hussain 1 , Martín Cárdenas Soto 2 , Rogério Elias Uagoda Soares 3 , Salvatore Martino 4 , Juan F. Rodríguez Rebolledo 1 , Omar Hamza 5 , Hernán Martínez Carbajal 6
1 University of Brasilia, Department of Civil and Environmental Engineering
3 University of Brasilia, Department of Geography
4 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks
5 University of Derby, College of Engineering and Technology

Keywords: Ambient seismic noise, rainfall, clayey landslide, terrestrial laser scanning
Abstract: The application of geophysical monitoring technologies may offer an opportunity to understand the dynamic of slopes in response to factors triggering their instability. In this study, Ambient Noise Interferometry was used as a monitoring approach on a man-made reduced-scale vertical slope and on a natural-scale landslide in Sobradinho (Brazil), under the influence of mechanical stress and rainfall, respectively. For both experiments, we adopted similar data acquisition system and processing workflow. After preprocessing of ambient seismic noise, the time-lapse changes were determined in terms of relative velocity changes using the moving window cross spectral technique. For the vertical slope, terrestrial laser scanning was also performed to detect crack or fissure generation. The prototype experiment results showed a decreasing trend of relative velocity changes and reached a minimum value of -0.6% at the end of the experiment. No change was detected on the digital elevation model that was computed from terrestrial laser scanning images, due to the absence of centimeter scale superficial fissures. At natural scale (Sobradinho landslide), no significant variation in relative velocity changes was detected for the rainy and non-rainy days, mainly because of the inadequate change in the degree of saturation, which was found within a relatively short period of data acquisition.
Selection of sites for the treatment and the final disposal of construction and demolition waste, using two approaches: An analysis for Mexico City
Sustainability
https://doi.org/10.3390/su11154077
Juan Antonio Araiza Aguilar 1 , Constantino Gutiérrez Palacios 2 , María Neftalí Rojas Valencia 3 , Hugo Alejandro Nájera Aguilar 4 , Rubén Fernando Gutiérrez Hernández 5 , Raúl Antonio Aguilar Vera 1
1 Universidad Nacional Autónoma de México, Instituto de Geografía
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería
5 Instituto Tecnológico de Tapachula, Departamento de Quimica y Bioquimica

Keywords: construction and demolition waste, location-allocation, multi criteria evaluation, network analyst
Abstract: This paper proposes a solution to the current problems of Mexico City (Ciudad de México) with respect to construction and demolition waste, through a spatial analysis to locate a waste treatment and disposal infrastructure. Two analysis methodologies, specifically the multi-criteria evaluation technique and network analysis, are used with the support of geographic information systems. The results of the multi-criteria evaluation technique indicate that the most suitable places for this infrastructure location are in the south and southeast of the study area, in the Tlalpan, Milpa Alta, Xochimilco and Cuajimalpa boroughs. The results of the network analysis technique indicate that four facilities strategically located in Miguel Hidalgo, Gustavo A. Madero, Tlahuac and Tlalpan boroughs would permit the provision of service to almost all waste generation points in the study area. Decision makers in Mexico City can use either of the two approaches. If the objective is to find the best location of a single place for the treatment or disposal of huge amounts of waste, the results obtained with the multi-criteria evaluation technique should be used. On the other hand, if waste treatment is favored over final disposal, decision makers should use the results of the network analysis technique.
Dexterous robotic manipulation via a dynamic sliding mode force/position control with bounded inputs
IET Control Theory & Applications
https://doi.org/10.1049/iet-cta.2018.5331
Javier Pliego Jiménez 1 , Marco Antonio Arteaga Pérez 2 , Pablo Sánchez Sánchez 3
1 CICESE, División de Física Aplicada

Keywords: control system synthesis, dexterous manipulators, stability, force control, end effectors, closed loop systems, variable structure systems, position control, manipulator dynamics
Abstract: Grasping and manipulation are common robotic tasks which require to properly control the interaction forces and position of multiple robots end-effectors. In this study, the authors focus on the problem of dexterous manipulation of rigid objects by means of a cooperative robotic system. Unlike several works, they consider the more complex case when the manipulated object is not mechanically attached to the robots' end-effectors. In addition, they address the control problem of designing a control law with continuous and bounded input torques for cooperative robots in constrained motion. To guarantee a stable grasp and a fine manipulation a centralised control algorithm based on the Orthogonalisation principle and a dynamic sliding mode control is proposed. The control algorithm does not require the knowledge of the dynamic model of the robot manipulators and manipulated object for implementation. Experimental results are presented to show the good performance of the proposed controller. In addition, the stability analysis of the closed-loop dynamics is developed.
A transformerless topology for a micro inverter with elevation factor of 1:10 for photovoltaic applications
International Journal of Electrical Power & Energy Systems
https://doi.org/10.1016/j.ijepes.2019.02.006
Benja Vidales Luna 1 , José Luis Monroy Morales 1 , Juan Ramón Rodríguez Rodríguez 2 , Manuel Madrigal Martínez 1 , D. Torres Lucio 1
1 Instituto Tecnológico de Morelia, Programa de Graduados e Investigación en Ingeniería Eléctrica (PGIIE)

Keywords: Transformerless, PV systems, Micro-inverter, DC/DC converters, DC/AC multilevel inverters
Abstract: In this paper, a modified transformerless inverter topology for photovoltaic (PV) applications is presented. This proposal is capable to produce a nine-level AC output from a single low DC voltage source with an efficiency of 95.59%, making it ideal as a micro-inverter. This is achieved by an elevation phase that generates two isolated DC outputs from a single source, using a redesigned DC/DC parallel boost converter that elevates up to ten times the input with no extreme duty cycles and performing it with fewer components compared to similar capacities topologies. These two isolated voltages are employed to feed an asymmetrical cascade cells DC/AC inverter. The theoretical fundaments and both simulation and experimental results presented in this paper validate the proposed topology.
Semantic reasoning in service robots using expert systems
Robotics and Autonomous Systems
https://doi.org/10.1016/j.robot.2019.01.007
Jesús Savage Carmona 1 , David Rosenblueth 2 , Mauricio Matamoros 3 , Marco Negrete 1 , Luis Contreras Toledo 4 , Julio Cruz 1 , Reynaldo Martell 1 , Hugo Estrada 1 , Hiroyuki Osada 4
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
3 Universität Koblenz-Landau, Department of Computervisualistik
4 Tamagawa University, Advance Intelligence and Robotics Research Center

Keywords: Service robots, Semantic reasoning, Knowledge representation
Abstract: This paper presents the semantic-reasoning module of VIRBOT, our proposed architecture for service robots. We show that by combining symbolic AI with digital-signal processing techniques this module achieves competitive performance. Our system translates a voice command into an unambiguous representation that helps an inference engine, built around an expert system, to perform action and motion planning. First, in the natural-language interpretation process, the system generates two outputs: (1) conceptual dependence, expressing the linguistic meaning of the statement, and (2) verbal confirmation, a paraphrase in natural language that is repeated to the user to confirm that the command has been correctly understood. Then, a conceptual-dependency interpreter extracts semantic role structures from the input sentence and looks for such structures in a set of known interpretation patterns. We evaluate this approach in a series of skill-specific semantic-reasoning experiments. Finally, we demonstrate our system in the general-purpose service robot test of the RoboCup-at-Home international competition, where incomplete information is given to a robot and the robot must recognize and request the missing information, and we compare our results with a series of baselines from the competition where our proposal performed best.
14C and 40Ar/39Ar radiometric dating and geologic setting of young lavas of Rancho Seco and Mazcuta volcanoes hosting archaeological sites at the margins of the Pátzcuaro and Zacapu lake basins (central Michoacán, Mexico)
Journal of Volcanology and Geothermal Research
https://doi.org/10.1016/j.jvolgeores.2019.106674
Israel Ramírez Uribe 1 , Claus Siebe 1 , Sergio Salinas 2 , Marie Noëlle Guilbaud 1 , Paul Layer 3 , Jeff Benowitz 3
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 University of Alaska, Department of Geology and Geophysics

Keywords: Pátzcuaro basin, Zacapu basin, Michoacán-Guanajuato Volcanic Field, Monogenetic volcanism, Radiocarbon, 40Ar/39Ar dating
Abstract: Geologic mapping of two neighbouring areas (totalling ?770 km2) centred around the Rancho Seco and Mazcuta monogenetic scoria cones and situated between the Pátzcuaro and Zacapu lake basins in the Michoacán-Guanajuato Volcanic Field (central portion of the Trans-Mexican Volcanic Belt), allowed the recognition of 62 Quaternary monogenetic volcanic structures, which include cinder cones with associated lava flows, domes, and small-to-medium sized shields. 40Ar/39Ar and 14C radiometric dating, petrography, and whole-rock chemical analyses of volcanic products provide a stratigraphic framework and insight into different eruptive styles, and erupted volumes (?45 km3 of calc-alkaline magma). Pliocene to Holocene monogenetic activity has been frequent in this region, forming structures, which are generally aligned along an ENE-WSW direction associated to the Morelia-Cuitzeo-Acambay normal fault system. The young Rancho Seco and Mazcuta volcanoes are of particular interest because their distal lava flows host the pre-Hispanic archaeological urban centres of Angamuco and Cortijo Viejo, respectively. The Rancho Seco scoria cone was radiocarbon-dated at 27,845 + 445/??425 yr BP and emitted at least six andesitic lava flows which were emplaced toward the SW (Lake Pátzcuaro) covering an area of 21.3 km2 with a volume of ?0.64 km3. The Mazcuta scoria cone dated at 7970 ± 135 yr BP produced five basaltic andesite-andesite lava flows toward the NW (Lake Zacapu), where they cover an area of 28.85 km2 with a volume of ?0.57 km3. The recently studied archaeological site of Angamuco became an important urban centre during the rise of the Tarascan Empire in the Post-Classic period (AD 900??1521), while the Cortijo Viejo site remains largely unexplored, but its occupation might fall within the same period. Although the young lava flows on which these sites are built seem inhospitable and barren with a rugged topography and rocky substrate unfit for agriculture, early inhabitants adapted and modified its surface according to their needs. Hence, these archaeological sites exemplify how a seemingly hostile landscape was ingeniously modified to establish population centres with patterns similar to those observed on lava flows elsewhere.
Energy consumption analysis for additive manufacturing processes
International Journal of Advanced Manufacturing Technology
https://doi.org/10.1007/s00170-019-04409-3
Horacio Gutiérrez Osorio 1 , Leopoldo Ruiz Huerta 2 , Alberto Caballero Ruiz 2 , Héctor Siller 3 , Vicente Borja Ramírez 1
2 Universidad Nacional Autónoma de México, Instituto de Ciencias Aplicadas y Tecnología
3 University of North Texas, Department of Engineering Technology

Keywords: Additivemanufacturing, DigitalManufacturing, Energy consumption, Mechanical properties, Greenmanufacturing
Abstract: Additive manufacturing (AM) is defined as the process of joining materials to make objects from 3D model data, usually layer upon layer, in contrast to subtractive or forming manufacturing methodologies. In studies of energy consumption in AM systems reported in the literature, the electric energy consumed by different technologies was measured directly in the main electrical supply wires of the machines, which does not represent the process energy consumption, because there are peripheral devices that do not have an influence on the process. In order to generate a better approach to the energy consumption of the AM process, this paper presents a proposal to measure the energy consumption directly in the system stage in which the AM processes are performed: preparing the material for extrusion, deposition, selection, gluing, curing, and so on, obtaining the geometry of a layer defined by an area with a certain thickness, and carrying out bonding between the layers to form a solid part. Because the combination of material and manufacturing processes determine the mechanical properties of a built part and because different materials and processes could be used to obtain these mechanical properties with different energy consumption values, the authors suggest mathematical models for three AM processes (material extrusion, vat photopolymerization, and material jetting) which predict the energy consumption and then compare the values with their experimental results, obtaining a difference of less than 10%, and find the parameters which define the differences in energy consumption among the processes.
The ~ AD 500??700 (Late Classic) El Astillero and El Pedregal volcanoes (Michoacán, Mexico): a new monogenetic cluster in the making?
Bulletin of Volcanology
https://doi.org/10.1007/s00445-019-1318-5
Patricia Larrea 1 , Claus Siebe 1 , Erick Juárez Arriaga 2 , Sergio Salinas 3 , Héctor Ibarra 2 , Harald Böhnel 2
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Centro de Geociencias

Keywords: Monogenetic cluster, Holocene, Radiocarbon dating, Paleomagnetic dating, Archeology, Volumetric estimations
Abstract: The recent identification of Holocene volcanic clusters in small areas within the Michoacán Guanajuato Volcanic Field (MGVF) opens several questions regarding future volcanic hazard assessments in this region. Documenting vent alignments and eruption recurrence intervals within clusters will provide parameters necessary for making temporal and spatial hazard evaluations. Here, we present a possible new case of a small cluster consisting of only two monogenetic volcanoes, El Astillero and El Pedregal located in the ~??4400-km2 Tancítaro-Nueva Italia region in the southwestern part of the MGVF, only 25 km to the south of Paricutin volcano. We determined from paleomagnetic and radiocarbon dating that El Astillero and El Pedregal most likely erupted one after the other between AD 500 and 700 (within the Late Classic period of Mesoamerican archeology). While the eruptions were likely separated by a short period of time, the exact length is difficult to ascertain. After the ~??6 years of total estimated eruption duration of the two volcanoes, both together occupied an area of 14.7 km2 and emitted a dense rock equivalent (DRE) volume of magma of ~??0.5 km3. Notable characteristics of the eruptions include a switch from the explosive activity exclusive of El Astillero (Strombolian) to effusive activity early after the initiation of the El Astillero eruption, a shift in the active vents, and a progressive change in the bulk magma composition from basaltic andesite to andesite throughout the duration of the eruption. This activity first formed the El Astillero scoria cone and tephra deposits followed by its lava field and ended with the emplacement of the El Pedregal viscous lavas. The discovery of pre-Hispanic pottery sherds and obsidian artifacts underneath the El Astillero tephra fallout unambiguously attests to human activities in the area before the eruption. Judging by their eruptive style, the eruptions probably had a limited impact on the small area affected and the surrounding human activities, but the hazard for this area remains since El Astillero and El Pedregal could represent the initial stages of a new cluster that is still in the making. If so, another eruption should be expected in this area again.
Mass transport and separation of species in an oscillating electro-osmotic flow caused by distinct periodic electric fields
Physica Scripta
https://doi.org/10.1088/1402-4896/ab2a9a
C. Teodoro 1 , Oscar Eladio Bautista Godínez 1 , Federico Méndez Lavielle 2
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: oscillating electroosmotic flow, effective diffusivity, species separation, microchannel
Abstract: In this work, we theoretically analyze how a passive solute is transported by an oscillating electro-osmotic flow along a parallel flat plate microchannel connecting two reservoirs with different concentrations. Three distinct periodic functions of the applied external electric field are considered: sawtooth, square, and parabolic waveforms, which are expressed as Fourier series. For each case, the dimensionless velocity and concentration fields are found analytically and, subsequently, the transport of the solute was obtained numerically. We distinguish four dimensionless parameters that govern the studied phenomenon: an angular Reynolds number, the Schmidt and Péclet numbers, and an electrokinetic parameter, this latter representing the ratio of the half-height of the microchannel to the Debye length. As has been reported in the specialized literature, the mass transport and separation of species in oscillating flows under the effect of an oscillatory pressure gradient can be increased with the angular frequency. For the present study, instead of a pressure gradient, we use oscillatory electro-osmotic forces, together with symmetric and asymmetric wall zeta potentials in the microchannel. For this condition, we prove that the transport of the solute is affected notably. In this paper, we show that controlling the type of the external electrical signal can also improve the mentioned tasks, depending on the Schmidt number, the electrokinetic parameter, and the angular Reynolds number.
Dynamics of a helical swimmer crossing an interface between two immiscible fluids
Physical Review Fluids
https://doi.org/10.1103/PhysRevFluids.4.083102
Jorge González Gutiérrez 1 , Salvador Osorio Ramírez 2 , Francisco Javier Solorio Ordaz 1 , Roberto Zenit 2
2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales

Keywords:
Abstract: In this study, we experimentally investigate the mechanical process of a self-propelled helical swimmer to move across an interface between two immiscible fluids. This configuration is aimed to emulate some aspects of the process used by bacteria to trespass mucus layers or epithelial cell membranes to cause infections. We consider two configurations: head-first and tail-first. We find that, in both cases, the head of the swimmer deforms the interface generating a meniscus that induces a significant reduction of the swimming speed, that lasts until the interface is pierced. In both cases, the dynamics of penetration is complex leading to significant variations of the swimming speed during the process. We observed interesting differences in the penetration dynamics for the two cases; we argue that the differences arise from the significantly different shape and direction of the menisci that forms during the penetration process. A model that accounts for thrust, drag, buoyant, and capillary forces is used to rationalize the results.
Typological analysis of slidequakes emitted from landslides: Experiments on an expander body pile and sobradinho landslide (Brasilia, Brazil)
Revista Escola de Minas
http://dx.doi.org/10.1590/0370-44672018720110
Yawar Hussain 1 , Sehar Hussain 2 , Salvatore Martino 3 , Martín Cárdenas Soto 4 , Omar Hamza 5 , Juan F. Rodríguez Rebolledo 1 , Rogério Elias Uagoda Soares 6 , Hernan Martínez Carbajal 7
1 University of Brasilia, Department of Civil and Environmental Engineering
2 University of Gujrat, Departmente of Chemical Engineering
3 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks
5 University of Derby, College of Engineering and Technology
6 University of Brasilia, Department of Geography

Keywords: expander body pile, extraction test, sonograms, spectral analysis, tropical clay
Abstract: Reactivation of a landslide is usually accompanied by microseismic signals emitted from the deforming soil mass. The reproduction of similar signals in a physical model test conducted under control conditions can allow researchers to explore and test such complicated signals to improve the prediction of full-scale failure. The present study investigates the similarity between the slidequakes (microseismicity) naturally emitted from an existing colluvial landslide (Sobradinho, Brazil) in response to rainfalls and the emissions generated by a pullout test of an expander body (EB) pile in tropical soil under controlled conditions. The microseismic signals emitted from both experimental sites (i.e. the landslide and the EB pile test) were recorded and compared. Data were acquired by mini-arrays of four short-period seismometers. For the signal nomenclature, a typological scheme was adopted, in which sonograms/spectral contents of the signals were used. As a result, short duration microseismic signals were observed during the pullout test. In contrast, at the Sobradinho landslide, the testing detected signals of different characteristics whose source mechanisms have remained ambiguous, mainly because of the short duration of the data campaigns. However, at the landslide, propagating events were observed that might be attributed to the energies generated by the river bedload during the heavy rains. The present study offers some insight into the pre-collapse dynamic behavior of unstable slopes in clayey formations.
Extended PI Feedback Tracking Control for Synchronous Motors
International Journal of Control, Automation and Systems
https://doi.org/10.1007/s12555-018-0312-6
Francisco Beltran Carbajal 1 , Rubén Tapia Olvera 2 , Irvin López García 1 , Antonio Valderrabano González 3 , Julio Cesar Rosas Caro 3 , José Luis Hernández Ávila 1

Keywords: Dynamic feedback control, PI feedback, synchronous motor, trajectory tracking
Abstract: A new dynamic feedback tracking control method of desired velocity and current profiles for permanent magnet synchronous motors, without the additional synthesis of disturbance observers and parametric identification methods, is introduced. Proportional-Integral (PI) feedback is properly extended for both efficient planned motion tracking control and simultaneous fast disturbance estimation. In this fashion, design of additional high-gain disturbance observers becomes unnecessary. This is, on-line dynamic load uncertainty estimation is simultaneously achieved by proposed tracking control implementation. Analytical and numerical results prove the efficient and robust tracking performance of controlled system variables on planned smooth motion profiles and a high-accuracy estimation of unknown high-order variable disturbances.
Track trajectories with model uncertainty using a robust differentiator
Revista Iberoamericana de Automática e Informática Industrial
https://doi.org/10.4995/riai.2019.10265
Pablo Sánchez Sánchez 1 , Alejandro Gutiérrez Giles 2 , Javier Pliego Jiménez 3 , Marco Antonio Arteaga Pérez 4
2 University of Naples Federico II, CREATE Consortium and Prisma Laboratory
3 CICESE, División de Física Aplicada

Keywords: Índice de desempeño, Control, Dinámica de robots, Planificación y seguimiento de trayectorias, Robots manipuladores, Diferenciador robusto
A Lagrange Relaxation Based Approach to Solve a Discrete-Continous Bi-Level Model
Open Journal of Optimization
https://m.scirp.org/doi.org/10.4236/ojop.2019.83009
Zaida E. Alarcón Bernal 1 , Ricardo Aceves García 1

Keywords: Bi-Level Programming, Lagrange Relaxation, Discrete-Continous Linear Bilevel
Abstract: In this work we propose a solution method based on Lagrange relaxation for discrete-continuous bi-level problems, with binary variables in the leading problem, considering the optimistic approach in bi-level programming. For the application of the method, the two-level problem is reformulated using the Karush-Kuhn-Tucker conditions. The resulting model is linearized taking advantage of the structure of the leading problem. Using a Lagrange relaxation algorithm, it is possible to find a global solution efficiently. The algorithm was tested to show how it performs.
Systems approach to develop a conceptual model of the service enterprises
Journal of Service Science and Management
https://m.scirp.org/doi.org/10.4236/jssm.2019.126048
Zaida E. Alarcón Bernal 1 , Ricardo Aceves García 1 , Arturo Fuentes Zenón 1

Keywords: Conceptual Model, Service Companies, Systems Approach, Service Science, Service System
Abstract: Considering the characteristics and particularities of services such as inseparability, perishability and variability, which make them ephemeral and little tangible, non-storable, and non-patentable, we can have a clear idea of the complexity that exists in planning, operating and solving problems in service companies. This situation demands the use of a different vision to analyze and study these companies and their problems. Therefore, the systems approach is presented and used for the construction of a conceptual model, as a support framework to situate and organize our perceptions, fix the structure of the problem, delimit the area of interest and define the relevant and non-relevant aspects. With the systems vision, we have been able to use the three basic forms of planning for decision making (strategic, tactical and operative) in the construction of a conceptual model. The methodology used that integrates these three basic forms of planning is presented in a logical-formal guide for the construction of the conceptual model of the service company. This representation identifies the basic elements of a business model such as customers, value proposition, infrastructure and information for decision making, as well as their interactions. The model obtained is simple, relevant, and easy to understand and at the same time does not oversimplify the complex operation of a service company.
Wireless Networks and Internet of Things (IoT) technologies based localization system for indoor sports player performance evaluation
International Journal of Engineering Research & Technology
https://www.ijert.org/wireless-networks-and-internet-of-things-iot-technologies-based-localization-system-for-indoor-sports-player-performance-evaluation

Abstract: This paper proposes the development of a player localization system using the Received Signal Strength Indicator (RSSI) parameter taken from IEEE 802.11 beacon frame, a positioning algorithm based on RSSI and trilateration technique to build a cost-effective solution for indoor sport environment as an alternative to video and Global Position System (GPS) localization technology. The visualization of the player's location on the court will be done through a web page.
Design of A Framework for Wireless Body Area Network Health Measurement Systems
International Journal of Engineering Research & Technology
https://www.ijert.org/design-of-a-framework-for-wireless-body-area-network-health-measurement-systems
Daniel Salcedo Peña 1 , Fátima Moumtadi 1

Keywords: WBAN, Embedded system, Physiological measurements.
Abstract: In this work we propose a design for embedded firmware to boost the development of Wireless Body Area Network systems for measuring of physiological data.
Cogeneration process technical viability for an apartment building: case study in Mexico
Processes
https://doi.org/10.3390/pr7020093
Hugo Valdés 1 , Gabriel León De los Santos 2
1 Uiversidad Católica del Maule, Departamento de Computación e Industrias

Keywords: cogeneration, technical viability, apartment building.
Abstract: The objective of this paper is to evaluate and to simulate the cogeneration process applied to an apartment building in the Polanco area (Mexico). Considering the building??s electric, thermal demand and consumption data, the cogeneration process model was simulated using Thermoflow© software (Thermoflow Inc., Jacksonville, FL, USA), in order to cover 1.1 MW of electric demand and to supply the thermal needs of hot water, heating, air conditioning and heating pool. As a result of analyzing various schemes of cogeneration, the most efficient scheme consists of the use of a gas turbine (Siemens model SGT-100-1S), achieving a cycle with efficiency of 84.4% and a heat rate of 14,901 kJ/kWh. The economic results of this evaluation show that it is possible to implement the cogeneration in the building with a natural gas price below US\$0.014/kWh. The use of financing schemes makes the economic results more attractive. Furthermore, the percentage of the turbine load effect on the turbine load net power, cogeneration efficiency, chimney flue gas temperature, CO2 emission, net heat ratio, turbine fuel flow and after burner fuel flow was also studied.
Revista Iberoamericana de Automática e Informática Industrial
https://doi.org/10.4995/riai.2018.10666
Oscar Danilo Montoya Giraldo 1 , Walter Gil González 2 , Sofía Ávila Becerril 3 , Alejandro Garces 2 , Gerardo Espinosa Pérez 3

Keywords: Control basado en pasividad, recursos energéticos distribuidos, convertidores controlados por voltaje, redes monofásicas de corriente alterna
Knowledge Graphs for Analyzing Thermal Comfort: A Proposal
Research in Computing Science
https://www.rcs.cic.ipn.mx/2019_148_9/
José Luis Jácome Domínguez 1 , Edgard Benítez Guerrero 1 , Guillermo Molero Castillo 2

Keywords: Knowledge Graphs, Thermal Comfort, Data Integration
Abstract: Knowledge Graphs (KGs) can be used to provide a unified, homogeneous view of heterogeneous data, which then can be queried and analyzed. In this paper, we explore the use of KGs to analyze the Thermal Comfort (TC) of users in specific environments (e.g. classrooms, hotel rooms). This implies the integration of several data sources that provide environmental variables (i.e. temperature, humidity), but also users?? physiological variables (i.e. temperature). Thus, this paper proposes a method to integrate and analyse environmental and physiological data through KGs in the context of TC.
State of the Art for the Optimization and Simulation of the Distribution of Hydrocarbons
International Journal of Combinatorial Optimization Problems and Informatics
https://ijcopi.org/index.php/ojs/article/view/121
Emilio Sampayo Trujillo 1 , Idalia Flores De La Mota 2
1 Petroleos Mexicanas, Exploración y Producción

Keywords: Hydrocarbons, distribution networks, optimization, simulation
Abstract: Hydrocarbons distribution networks are strategic for the oil industry. That is why the research being presented in this article focuses on thoroughly reviewing everything that has been developed on the subject in different parts of the world over the last fifteen years. The reviewed articles have been classified according to the models that were built, the methods used to solve said models and the approach that has been developed. Because of the characteristics of the problem in general, there is more research available that uses mathematical models and finds the solution with different optimization methods. Secondly though no less important we found simulation models for studying some aspects that are differentiated from the optimization models.
Wealth and Income Distribution: A review towards new trends
International Journal of Social Science and Economic Research
http://www.ijsser.org/more2019.php?id=26
Javier Lara De Paz 1 , Idalia Flores De La Mota 1 , Gabriel Policroniades Chípuli 1 , O. Sashiko Shirai 1

Keywords: Wealth and income Distribution, Power Law, Economic Complex Systems, Econophysics, Agent-Based Models, Complex Networks
Abstract: The increasing inequality observed in recent years between the income of 1% of the population with respect to the rest, a new interest arose in the study of the distribution of wealth and income, questioning the effectiveness of traditional economic models even provoking economists to consider other approaches to study this problem. In present paper a revision of some of these approaches is made, from the statistical part, going over Pareto's work, and the later works of Gibrat, Piketty, among others, and how complexity sciences have contributed through the econophysics and Agents-Based Models, from a Bottom-Up and Top-Down perspective, until the emergence of complex networks. Getting with it a contribution to find a more robust view of the problem.
Virtual sensing of load forces in hydraulic actuators using second- and higher-order sliding modes
Control Engineering Practice
https://doi.org/10.1016/j.conengprac.2019.104151
Michael Ruderman 1 , Leonid Fridman Golredich 2 , Philipp Pasolli 1
1 University of Agder, Faculty of Engineering and Science

Keywords: Robust exact differentiator, High-order sliding mode observer, hydraulic actuator, force sensing
Abstract: External load forces are challenging for sensing or estimating in the hydraulic actuators. Once it is due to inconvenient instrumentation of the force sensors, especially on an open-end mechanical interface. The other way, the complex nonlinear system behavior aggravates reconstructing the system states in a robust and real-time suitable manner. This paper proposes a sensorless estimation of external load forces in standard hydraulic actuators by using a well-established equivalent output injection of the second-order sliding mode and also higher-order sliding mode differentiator. Only the basic inertial and frictional parameters are assumed to be known from an initial identification without external load. Afterwards, the robust exact differentiators are used in order to reconstruct the system states. Noisy signals of the cylinder chamber pressures and piston stroke are the single quantities available from the measurement. An experimental case study, accomplished on the setup of two hydraulic cylinders arranged and operated in antagonistic way, is provided. The force-cell on the rigid interface between both cylinders is used for reference measurements and evaluation of the estimation algorithms. Two estimation approaches, one of the 2nd and another of the 4th order, are assessed in performance and compared to each other along with discussion.
Generalized Model Reference Adaptive Control by Means of Global HOSM Differentiators
IEEE Transactions on Automatic Control
https://doi.org/10.1109/TAC.2018.2862466
Tiago Roux Oliveira 1 , Víctor Hugo Pereira Rodrigues 1 , Leonid Fridman Golredich 2
1 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering

Keywords: Adaptive control, Adaptation models, Upper bound, Observers, Output feedback, Asymptotic stability, Stability analysis
Abstract: In this paper, we combine a global differentiator based on higher-order sliding modes (HOSM) and dynamic gains with classical model reference adaptive control (MRAC) schemes to solve the relevant and yet open problem of trajectory tracking via output feedback of uncertain plants with arbitrary relative degree in a simple-closed form for the control design. The gains of the differentiator are adapted through state-norm observers for the unmeasured state, whereas the control parametrization explores the input-output filters commonly used in the MRAC design. Global asymptotic stability and robust exact tracking are rigorously demonstrated. Simulations highlight the claimed properties as well as the remarkable simplicity of the proposed adaptive control system using robust exact differentiators when compared to more involved alternatives found in standard approaches. The theoretical results are also illustrated with an application to bilateral teleoperation.
Two relay control robustification by continuous switched integral sliding modes
IET Control Theory & applications
https://doi.org/10.1049/iet-cta.2018.5639
Juan Eduardo Velázquez Velázquez 1 , Rosalba Galván Guerra 1 , Leonid Fridman Golredich 2 , Rafael Iriarte 2
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo

Keywords: control system synthesis, nonlinear control systems, observers, robust control, variable structure systems
Abstract: Robust generation of self-oscillation for mechanical systems in the presence of matched uncertainties/perturbations based on a two-relay controller, which naturally has a switched structure, is presented. Two scenarios are considered: the case when all the system states are available and the case when only output information is measured. In both scenarios, a continuous switched integral sliding modes controller is implemented to guarantee theoretically exact compensation of matched uncertainties/perturbations before the first switching. The chattering attenuation in the presence of fast parasitic dynamics can be realised by a switched gain strategy of the super-twisting algorithm. In the output-based scenario, the observer and the controller are initiated sequentially. A super twisting-based observer is used, guaranteeing theoretically exact reconstruction of the states before the controller is activated. The observer gains are also switched to diminish the chattering. Once the observer has converged, the reconstructed state is used in the controller to achieve the control objective. The observer and controller are designed to attain convergence before the first switching.
Stabilization of systems with switchings on the axis of their coordinates and its input-to-state properties
Nonlinear Analysis: Hybrid Systems
https://doi.org/10.1016/j.nahs.2018.10.008
Andrea Aparicio 1 , Leonid Fridman Golredich 1 , Denis Efimov 2