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Artículos publicados en: 2017

The effect of vertical scaling on the estimation of the fractal dimension of randomly rough surfaces
Applied Surface Science
Rafael Schouwenaars Franssens 1 , Víctor Hugo Jacobo Armendáriz 1 , Armando Ortiz Prado 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fractal surfaceTriangular prism methodDetrended fluctuationRoughnessImage analysisSimulation
Abstract: Fractal analysis of randomly rough surface is an interesting tool to establish relationships between surface geometry and properties. Nonetheless, the observation that different methods to determine the fractal dimension D yield different results has raised questions about its physical meaning. This work shows that such variations are caused by the mathematical details of the methods used, particularly by the effect of vertical scaling. For the triangular prism method (TPM), applied to fractional Brownian motion, the effect of vertical scaling on the numerical estimation of D can be addressed through analytic calculations. The analytic approach was compared to simulations of surface topography obtained by the random midpoint algorithm (RMA) using TPM, box count method (BCM), differential box count (DBC) and detrended fluctuation analysis (DFA). The effect of scaling for TPM is considerable and coincides with the mathematical predictions. BCM and DBC show no effect of scaling but provide poor estimates at high D. A small effect was found for DFA. It is concluded that TPM provides a precise estimate of D which is independent of vertical scaling for infinite image resolution. At finite resolutions, the estimation error on D can be minimised by choosing an optimal vertical scaling factor.
Compositional and volumetric development of a monogenetic lava flow field: The historicl case of Paricutin (Michoacán, México)
Journal of Volcanology and Geothermal Research
Patricia Larrea 1 , Sergio Salinas 2 , Elisabeth Widom 3 , Claus Siebe 1 , Robbyn Abbitt 4
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Miami University, Department of Geology & Environmental Earth Science
4 Miami University, Deparment of Geography

Keywords: Paricutin volcano, Michoacán??Guanajuato volcanic field, Monogenetic volcanism, Eruptive phase, ArcGIS mapping, Lava field volumetric estimations
Abstract: Paricutin volcano is the youngest and most studied monogenetic volcano in the Michoacán-Guanajuato volcanic field (Mexico), with an excellent historical record of its nine years (February 1943 to March 1952) of eruptive activity. This eruption offered a unique opportunity to observe the birth of a new volcano and document its entire eruption. Geologists surveyed all of the eruptive phases in progress, providing maps depicting the volcano's sequential growth. We have combined all of those previous results and present a new methodological approach, which utilizes state of the art GIS mapping tools to outline and identify the 23 different eruptive phases as originally defined by Luhr and Simkin (1993). Using these detailed lava flow distribution maps, the volume of each of the flows was estimated with the aid of pre- and post-eruption digital elevation models. Our procedure yielded a total lava flow volume ranging between 1.59 and 1.68 km3 DRE, which is larger than previous estimates based on simpler methods. In addition, compositional data allowed us to estimate magma effusion rates and to determine variations in the relative proportions of the different magma compositions issued during the eruption. These results represent the first comprehensive documentation of the combined chemical, temporal, and volumetric evolution of the Paricutin lava field and provide key constraints for petrological interpretations of the nature of the magmatic plumbing system that fed the eruption.
Graphitizing Non-graphitizable Carbons by Stress-induced Routes
Scientific Reports
Maziar Ghazinejad 1 , Sunshine Holmberg 1 , Oscar Pilloni 2 , Laura Oropeza Ramos 2 , Marc Madou 1
1 University of California, Department of Mechanical and Aerospace Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Carbon nanotubes and fullerenes, design, synthesis and processing, electrochemistry
Abstract: Graphitic carbons?? unique attributes have attracted worldwide interest towards their development and application. Carbon pyrolysis is a widespread method for synthesizing carbon materials. However, our understanding of the factors that cause differences in graphitization of various pyrolyzed carbon precursors is inadequate. We demonstrate how electro-mechanical aspects of the synthesis process influence molecular alignment in a polymer precursor to enhance its graphitization. Electrohydrodynamic forces are applied via electrospinning to unwind and orient the molecular chains of a non-graphitizing carbon precursor, polyacrylonitrile. Subsequently, exerting mechanical stresses further enhances the molecular alignment of the polymer chains during the formative crosslinking phase. The stabilized polymer precursor is then pyrolyzed at 1000?°C and characterized to evaluate its graphitization. The final carbon exhibits a uniformly graphitized structure, abundant in edge planes, which translates into its electrochemical kinetics. The results highlight the significance of physical synthesis conditions in defining the structure and properties of pyrolytic carbons.
Automated detection of atrial fibrillation ECG signals using two stage VMD and atrial fibrillation diagnosis index
Journal of Mechanics in Medicine and Biology
Rajesh K. Tripathy 1 , Mario Roberto Arrieta Paternina 2 , Juan Gregorio Arrieta Paternina 3 , Priyabrata Pattanaik 1
1 Siksha 'O' Anusandhan Deemed to be University, Faculty of Engineering and Technology
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Sanatorio Güemes

Keywords: Atrial fibrillation, electrocardiogram, two-stage variational mode decomposition, deep belief network, performance measures and atrial fibrillation diagnosis index
Abstract: Atrial fibrillation (AF) is a common atrial arrhythmia occurring in clinical practice and can be diagnosed using electrocardiogram (ECG) signal. The conventional diagnostic features of ECG signal are not enough to quantify the pathological variations during AF. Therefore, an automated detection of AF pathology using the new diagnostic features of ECG signal is required. This paper proposes a novel method for the detection of AF using ECG signals. In this work, we are using a novel nonlinear method namely, the two-stage variational mode decomposition (VMD) to analyze ECG and deep belief network (DBN) for automated AF detection. First, the ECG signals of both normal sinus rhythm (NSR) and AF classes are decomposed into different modes using VMD. The first mode of VMD is decomposed in the second stage as this mode captures the atrial activity (AA) information during AF. The remaining modes of ECG captures the ventricular activity information. The sample entropy (SE) and the VMD estimated center frequency features are extracted from the sub-modes of AA mode and ventricular activity modes. These extracted features coupled with DBN classifier is able to classify normal and AF ECG signals with an accuracy, sensitivity and specificity values of 98.27%, 97.77% and 98.67%, respectively. We have developed an atrial fibrillation diagnosis index (AFDI) using selected SE and center frequency features to detect AF with a single number. The system is ready to be tested on huge database and can be used in main hospitals to detect AF ECG classes.
Paleomagnetically inferred ages of a cluster of Holocene monogenetic eruptions in the Tacámbaro-Puruarán area (Michoacán, México): Implications for volcanic hazards
Journal of Volcanology and Geothermal Research
Ahmed Nasser Mahgoub 1 , Harald Böhnel 1 , Claus Siebe 2 , Sergio Salinas 3 , Marie Noëlle Guilbaud 2
1 Universidad Nacional Autónoma de México, Centro de Geociencias
2 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Paleomagnetic dating, Monogenetic cluster, Holocene, Lava flows, Michoacán, México
Abstract: The paleomagnetic dating procedure was applied to a cluster of four partly overlapping monogenetic Holocene volcanoes and associated lava flows, namely La Tinaja, La Palma, Mesa La Muerta, and Malpaís de Cutzaróndiro, located in the Tacámbaro-Puruarán area, at the southeastern margin of the Michoacán-Guanajuato volcanic field. For this purpose, 21 sites distributed as far apart as possible from each other were sampled to obtain a well-averaged mean paleomagnetic direction for each single lava flow. For intensity determinations, double-heating Thellier experiments using the IZZI protocol were conducted on 55 selected samples. La Tinaja is the oldest of these flows and was dated by the 14C method at ~ 5115 ± 130 years BP (cal 4184??3655 BCE). It is stratigraphically underneath the other three flows with Malpaís de Cutzaróndiro lava flow being the youngest. The paleomagnetic dating procedure was applied using the Matlab archaeo-dating tool in couple with the geomagnetic field model SHA.DIF.14k. Accordingly, for La Tinaja several possible age ranges were obtained, of which the range 3650??3480 BCE is closest to the 14C age. Paleomagnetic dating on La Palma produced a unique age range of 3220??2880 BCE. Two ages ranges of 2240??2070 BCE and 760??630 BCE were obtained for Mesa La Muerta and a well-constrained age of 420??320 BCE for Malpaís de Cutzaróndiro. Although systematic archaeological excavations have so far not been carried out in this area, it is possible that the younger eruptions were contemporary to local human occupation. Our paleomagnetic dates indicate that all four eruptions, although closely clustered in space, occurred separately in time with varying recurrence intervals ranging between ~ 300 and ~ 2300 years. This finding should be considered when constraining the nature of the magmatic plumbing system and developing a strategy aimed at reducing risk in the volcanically active Michoacán-Guanajuato volcanic field, where several young monogenetic volcano clusters have been identified recently. These enigmatic small "flare-ups? (outbursts of small pods of magma in geologically short periods of time within a small area) have also been encountered in other subduction-related volcanic fields around the globe (e.g. Cascades arc in the western U.S.A.) and still require to be investigated by geophysical and petrological means in order to understand their origin.
Tomografía de resistividad eléctrica 3D en la Catedral de Morelia, México
Arqueologia Iberoamericana
Gerardo Cifuentes Nava 1 , Roberto Cabrer Torres 2 , Andrés Tejero Andrade 3 , Esteban Hernández Quintero 1 , Alejandro García Serrano 3 , René E. Chávez Segura 1 , Avto Goguitchaichvili 1 , Miguel Ángel Cervantes Solano 2
1 Universidad Nacional Autónoma de México, Instituto de Geofísica
2 Universidad Nacional Autónoma de México, Escuela Nacional de Estudios Superiores - Morelia
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Catedral de Morelia, exploración geofísica, tomografía de resistividad eléctrica tridimensional, estructuras subterráneas
Abstract: La tradición oral en la ciudad de Morelia, México, así como evidencias parciales en algunos edificios, han llevado a la creencia de la existencia de túneles subterráneos en el centro de esta ciudad, los cuales pertenecerían a la época colonial de nuestro país. Dicho centro fue declarado patrimonio cultural de la humanidad en 1991 por la UNESCO, por lo que es poco factible la excavación o perforación directa destructiva con la intención de explorar. En este contexto, la implementación de técnicas no invasivas es perfecta para localizar zonas de interés, de tal forma que los métodos de exploración geofísica son adecuados, al no ser destructivos y proporcionar una imagen del subsuelo para corroborar la existencia indirecta de estructuras en profundidad. Se presentan los estudios con tomografía de resistividad eléctrica tridimensional (TRE-3D) llevados a cabo en 2014, 2016 y 2017 en la Catedral de Morelia y su frente norte, en donde se pueden ubicar estructuras organizadas no acordes con el entorno geológico del sitio, los cuales pueden suministrar indicios de la existencia de diversas estructuras de origen antrópico. La TRE-3D aplicada para este estudio es una combinación entre metodologías convencionales y no convencionales; ofrece una imagen de la distribución de estructuras en profundidad que muestran características concordantes con tradiciones orales y hechos históricos documentados referentes al desarrollo de la Catedral de Morelia a través del tiempo.
Removal of arsenic III and V from laboratory solutions and contaminated groundwater by metallurgical slag through anion-induced precipitation
Environmental Science and Pollution Research
Rafael Schouwenaars Franssens 1 , Claudia Victoria Montoya Bautista 2 , Elizabeth Diane Isaacs Páez 3 , Myriam Solís López 1 , Rosa María Ramírez Zamora 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Autónoma de San Luis Potosí

Keywords: AdsorptionArsenic (III) and (V)GroundwaterIsothermsKineticsMetallurgical slagPrecipitation
Abstract: Metallurgical slag was used for the simultaneous removal of high concentrations of arsenite and arsenate from laboratory solutions and severely contaminated groundwater. Apart from demonstrating the high efficiency of arsenic removal in presence of competing species, the work aims to explore the physicochemical mechanisms of the process by means of microscopy observation and a detailed statistical analysis of existing kinetic and isotherm equations. Fitting was performed by non-linear least squares using weighted residuals; ANOVA and bootstrap methods were used to compare the models. Literature suggests that the metal oxides in the slag are efficient adsorbents of As(III) and (V). However, the low surface area of the slag precludes adsorption; SEM observation provide evidence of a mechanism of co-precipitation of lixiviated cations with contaminant anions. The reaction kinetics provide essential information on the interaction between the contaminants, particularly on the common ion effect in groundwater. The Fritz-Schlünder isotherm allows modelling the saturation effect at low slag doses. The efficiency of the process is demonstrated by an arsenic removal of 99% in groundwater using 4-g slag/L, resulting in an effluent with 0.01 mg As/L, which is below Mexican and international standards for drinking water. © 2017, Springer-Verlag GmbH Germany.
Measurement and nonlinear behavioral modeling of the dynamic bias current in an LTE-A Chireix PA
Microwave and Optical Technology Letters
José Alejandro Galaviz Aguilar 1 , Chang Hsiu Chen 2 , Francisco Javier Martínez Rodríguez 3 , Patrick Roblin 2 , J. C. Núñez Pérez 1
1 Instituto Politécnico Nacional, CITEDI
2 The Ohio State University, Department of Electrical and Computer Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Chireix outphasing amplifier, instantaneous bias current, NARMA, nonlinear modeling
Abstract: The measurement and modeling of the dynamic power dissipation of a dual-input Chireix power amplifier driven by LTE modulated signals is reported to optimize its dynamic efficiency. Two memory cubic spline FIR and NARMA behavioral models are verified to accurately predict the measured instantaneous PA bias-current and power dissipation as a function of the PA RF output power.
Stand-alone core sensitivity and uncertainty analysis of ALFRED from Monte Carlo simulations
Annals of Nuclear Energy
Alejandría D. Pérez Valseca 1 , Gilberto Espinosa Paredes 1 , Juan Luis François Lacouture 2 , Alejandro Vázquez Rodríguez 1 , Cecilia Martín del Campo 2
1 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: ALFRED, Lead-Cooled Fast Reactor, Monte Carlo simulation, Fuel heat transfer, Thermal-fluid, Neutronic process
Abstract: The aim of this paper is the sensitivity and uncertainty analysis of a Lead-Cooled Fast Reactor (LFR) based on Monte Carlo simulation of sizes up to 2000. The methodology developed in this work considers the uncertainty of sensitivities and uncertainty of output variables due to a single-input-variable variation. The Advanced Lead fast Reactor European Demonstrator (ALFRED) is analyzed to determine the behavior of the essential parameters due to effects of mass flow and temperature of liquid lead. The ALFRED core mathematical model developed in this work is fully transient, which takes into account the heat transfer in an annular fuel pellet design, the thermo-fluid in the core, and the neutronic processes, which are modeled with point kinetic with feedback fuel temperature and expansion effects. The sensitivity evaluated in terms of the relative standard deviation (RSD) showed that for 10% change in the core inlet flow, the response in thermal power change is 0.58%, and for 2.5% change in the inlet lead temperature is 1.87%. The regression analysis with mass flow rate as the predictor variable showed statistically valid cubic correlations for neutron flux and linear relationship neutron flux as a function of the lead temperature. No statistically valid correlation was observed for the reactivity as a function of the mass flow rate and for the lead temperature. These correlations are useful for the study, analysis, and design of any LFR.
Optimization of a Cellular Glass Ceramic Produced from Water Potabilization Sludge for Structural and Chemical Applications
Advanced Engineering Materials
Rosa María Ramírez Zamora 1 , Fabricio Espejel Ayala 2 , Iván Emilio Martínez Herrera 1 , Víctor Manuel Sánchez Orendain 1 , Gabriela Díaz 3 , Myriam Solís López 4 , Rafael Schouwenaars Franssens 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Electroquimica, Centro de Investigación y Desarrollo Tecnológico
3 Universidad Nacional Autónoma de México, Instituto de Física
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Waste sludge generated in the potabilization of surface water is used to produce cellular materials by mixing with clay and firing at 1?250?°C. An iron-rich glassy matrix with crystals of mullite and albite is formed. Porosity is generated by the slow release of H2O, which originates from the dehydroxilation of lepidocrocite at high temperature. The sludge/clay ratio and the sludge granulometry determine the properties of the product: from highly porous cellular foams to denser materials with high strength. Laboratory tests for both kinds of products show that the latter can be used as aggregates for low-density structural concrete. The former serve as a support material for the catalytic reduction of NOx in exhaust gases. Deposition conditions for Fe- and Pt-nanoparticles are optimized by experimental design, resulting in NOx-conversion rates close to 100%.
Hydrodynamic dispersion in a combined magnetohydrodynamic- electroosmotic-driven flow through a microchannel with slowly varying wall zeta potentials
Physics of Fluids
Carlos Vargas 1 , José Carlos Arcos Hernández 2 , 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
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: The effective dispersion coefficient of a neutral solute in the combined electroosmotic (EO) and magnetohydrodynamic (MHD)-driven flow of a Newtonian fluid through a parallel flat plate microchannel is studied. The walls of the microchannel are assumed to have modulated and low zeta potentials that vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient is solved using the lubrication approximation theory. The solution of the electrical potential is based on the Debye-Hückel approximation for a symmetric (Z:Z) electrolyte solution. The EO and MHD effects, together with the variations in the zeta potentials of the walls, are observed to notably modify the axial distribution of the effective dispersion coefficient. The problem is formulated for two cases of the zeta potential function. Note that the dispersion coefficient primarily depends on the Hartmann number, on the ratio of the half height of the microchannel to the Debye length, and on the assumed variation in the zeta potentials of the walls.
Probabilistic Wind Risk Assessment Induce by Hurricanes on Economically Vulnerable Households in Mexico
Natural Hazards Review
Miguel A. Jaimes 1 , Mauro Niño Lázaro 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Case studies, Wind engineering, Hurricanes and typhoons, Probability, Wind loads, Economic factors, Developing countries, Natural disasters, Mexico
Abstract: The economically vulnerable households in Mexico are used as an illustrative case study to present wind risk assessment induced by hurricanes, in which the risk parameters are assessed in an event-based probabilistic framework using a set of hazardous events integrated probabilistically, including all uncertainties related to hazard, vulnerability, and risk assessment. The hazard is defined as a stochastic set of events that describes the spatial distribution, the annual frequency, and the randomness of the hazard intensity. The structural vulnerability is defined, for specific dwelling types, in terms of the expected damage and its corresponding standard deviation. The risk is expressed in four different economic terms: (1) expected loss for a single event, (2) average annual loss as a percentage of the reconstruction cost of the exposed asset, (3) pure premium, and (4) loss exceedance curve. It is observed that the expected annual loss for this type of dwelling in Mexico is approximately USD 39.06 million, and the probable maximum loss associated with a return period of 1,500 years is approximately USD 1,181 million. It is concluded that these quantitative metrics are of particular importance, especially to define risk transfer or retaining schemes, such as that employed by the Mexican Insurance Commission, which uses a 1,500-year return period to fix the solvency of insurance companies in Mexico, the Natural Disaster Fund, FONDEN, or a Catastrophe bond (CAT bond), used by the Mexican government.
Sensitivity analysis on ram speed of a direct extrusion process model using a porthole die through CEL method
The International Journal of Advanced Manufacturing Technology
M. Cristobal 1 , E. Ramírez 1 , Osvaldo Ruiz Cervantes 1 , Armando Ortiz Prado 1 , Víctor Hugo Jacobo Armendáriz 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: FEM analysis, Coupled Eulerian-Lagrangian (CEL), Pipe extrusion, Porthole die
Abstract: In this paper, a tube extrusion process by finite element was analyzed, using coupled Eulerian-Lagrangian method (CEL) due to the severe deformation that material presents and thereby avoids distortion of the mesh and adaptive meshing used in Lagrangian models, in order to obtain stress distribution, strains, extrusion force, and flow material behavior. Four isothermal models were performed by modifying the sensitivity of ram speed using discrete rigid tools with general contact option to simulate the interaction between them; 7005 aluminum was considered as the material to be extruded. In order to reduce high computational time application, speed was increased to observe its influence on the results, in other words the variations between the models. As a consequence of this analysis, it was found that while the kinetic energy does not exceed 5 to 10 % of whole internal energy, material flow behavior and stress level are not affected.
Meteorological drought features in northern and northwestern parts of Mexico under different climate change scenarios
Journal of Arid Land
Carlos Agustín Escalante Sandoval 1 , Pedro Núñez García 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: meteorological drought, synthetic simulation, climate change, water stress, evapotranspiration
Abstract: Meteorological drought has been an inevitable natural disaster throughout Mexican history and the northern and northwestern parts of Mexico (i.e., the studied area), where the mean annual precipitation (MAP) is less than 500 mm, have suffered even more from droughts in the past. The aim of this study was to conduct a meteorological drought analysis of the available MAP data (1950??2013) from 649 meteorological stations selected from the studied area and to predict the drought features under the different IPCC-prescribed climate change scenarios. To determine the long-term drought features, we collected 1?104 synthetic samples using the periodic autoregressive moving average (PARMA) model for each rainfall series. The simulations first consider the present prevailing precipitation conditions (i.e., the average from 1950 to 2013) and then the precipitation anomalies under IPCC-prescribed RCP 4.5 scenario and RCP 8.5 scenario. The results indicated that the climate changes under the prescribed scenarios would significantly increase the duration and intensity of droughts. The most severe impacts may occur in the central plateau and in the Baja California Peninsula. Thus, it will be necessary to establish adequate protective measures for the sustainable management of water resources in these regions.
LEA: An Algorithm to Estimate the Level of Location Exposure in Infrastructure-Based Wireless Networks
Mobile Information Systems
Francisco García 1 , Javier Gómez 1 , Miguel López Guerrero 2 , Víctor Rangel Licea 1 , Michael Pascoe Chalke 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Unidad Iztapalapa

Abstract: Location privacy in wireless networks is nowadays a major concern. This is due to the fact that the mere fact of transmitting may allow a network to pinpoint a mobile node. We consider that a first step to protect a mobile node in this situation is to provide it with the means to quantify how accurately a network establishes its position. To achieve this end, we introduce the location-exposure algorithm (LEA), which runs on the mobile terminal only and whose operation consists of two steps. In the first step, LEA discovers the positions of nearby network nodes and uses this information to emulate how they estimate the position of the mobile node. In the second step, it quantifies the level of exposure by computing the distance between the position estimated in the first step and its true position. We refer to these steps as a location-exposure problem. We tested our proposal with simulations and testbed experiments. These results show the ability of LEA to reproduce the location of the mobile node, as seen by the network, and to quantify the level of exposure. This knowledge can help the mobile user decide which actions should be performed before transmitting.
A perturbative thermal analysis for an electro-osmotic flow in a slit microchannel based on a Lubrication theory
International Journal of Thermal Sciences
Edgar Ali Ramos Gómez 1 , Oscar Eladio Bautista Godínez 2 , José Joaquín Lizardi Del Ángel 3 , Federico Méndez Lavielle 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 Universidad Autónoma de la Ciudad de México, Colegio de Ciencia y Tecnología

Keywords: Microchannels, Electro-osmotic flow, Non-isothermal, Joule heating
Abstract: In this work, we develop a new thermal analysis for an electro-osmotic flow in a rectangular microchannel. The central idea is very simple: the Debye length that defines the length of the electrical double-layer depends on temperature T. Therefore, if exists any reason to include variable temperature effects, the above length should be utilized with caution because it appears in any electro-osmotic mathematical model. For instance, the presence of the Joule effect is a source that can generate important longitudinal temperature gradients along the microchannel and the isothermal hypothesis is no longer valid. In this manner, the Debye length is altered and as a consequence, new longitudinal temperature gradient terms appear into the resulting governing equations. These terms are enough to change the electric potential and the flow field. Taking into account the above comments, in the present study the momentum equations together with the energy and Poisson conservation equations are solved by using a regular perturbation technique. For this purpose, we introduce a dimensionless parameter α that measures the temperature deviations of a reference temperature. For practical cases, this parameter is small compared with unity and the theoretical predictions show; however, that for the used values of this parameter, the volumetric flow rate decreases in comparison with the isothermal case.
Microtremor Response of a Mass Movement in Federal District of Brazil
Anuário do Instituto de Geociências
Yawar Hussain 1 , Hernán Martínez Carbajal 2 , Martín Cárdenas Soto 3 , Rogério Elias Uagoda Soares 4 , Salvatore Martino 5 , Muhammad B. Hussain 6
1 University of Brasilia, Department of Civil and Environmental Engineering
2 Universidad Nacional de Colombia, Facultad de Minas
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 University of Brasilia, Department of Geography
5 University of Rome "Sapienza""", Department of Earth Sciences and Research Center for Geological Risks
6 University of Lahore, Department of Physics

Keywords: Seismic noise, Power Spectral Density, Probability Density Function, HVSR, f-k analysis
Abstract: The present study provides a brief description of the ambient noise recorded at a slow moving mass movement in Ribeirão Contagem Basin. The area is an interesting natural laboratory as river detachment processes in a number of diferent stages can be identiied and are easily accessible. We investigate the site dynamic characteristics of the study area by recording ambient noise time-series at nine points, using portable nine three-component short period seismometers. The time-series are processed to give both horizontal to vertical spectral ratio (HVSR) curves as well as time-frequency plots of noise power spectral density (SPD). The HVSR curves illustrate and quantify aspects of site resonance efects due to the local geological setting. Probability density function (PDF) shows that noise level lies well between new high noise model (NHNM) and new lower noise model (NLNM) and their probabilities are higher above 2 Hz. HVSR curves present a uniform lithologically controlled peak at 2 Hz. Directional properties of the waveield are determined by beamforming method. The f-k analysis results in the E-W component show that at 5 Hz phase velocities are close to 1700 m/s while at 10 Hz dropped to 250 m/s. We observed that between 5 and 16 Hz the incoming waveield arrive from 260 degrees. Further studies will apply a detailed noise analysis for relating the dynamics of the landslide (which can be retriggered by river erosion as well as rainfalls and seismic shaking) to possible changes in detectable physical properties.
Comparison between LSP and MFCC parameterizations in a Spanish Speech Synthesis System
Research in Computing Science
Carlos Franco 1 , Abel Herrera Camacho 2 , Boris Escalante Ramírez 2 , Fernando Del Río 2
1 Benemérita Universidad Autónoma de Puebla, Facultad de Artes
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Speech synthesis, line spectral pair, MFCC, Spanish language synthesis.
Abstract: Voice parameterization using Line Spectral Pair was implemented to a Mexican Spanish HMM-based Speech Synthesis System. Five phrases were synthesized and statistically validated by applying a MOS test to 30 listeners who analyzed the original voices versus synthetic voice. Results were compared with a synthesizer where MFCC was used as voice parameterization. Two aspects were evaluated on the voice: Naturalness and Intelligibility. The comparison shows that LSP parameterization is above the mean score and pointed better than MFCC.
Modes of Variability of Annual and Seasonal Rainfall in Mexico
Journal of the American Water Resources Association
Gabriela Álvarez Olguín 1 , Carlos Agustín Escalante Sandoval 2
1 Universidad Tecnológica de la Mixteca, Instituto de Hidrología
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: climatic variability, regionalization of precipitation, trend and change point
Abstract: The aim of this study is to identify temporal and spatial variability patterns of annual and seasonal rainfall in Mexico. A set of 769 weather stations located in Mexico was examined. The country was divided into 12 homogeneous rainfall regions via principal component analysis. A Pettitt test was conducted to perform a homogeneity analysis for detecting abrupt changes in mean rainfall levels, and a Mann?Kendall test was conducted to examine the presence of monotonically increasing/decreasing patterns in the data. In total, 14.4% of the annual series was deemed nonstationary. Fourteen percent of the samples were nonstationary in the winter and summer, and 9% were nonstationary in the spring and autumn. According to the results, the nonstationarity of some seasonal rainfall series may be associated with the presence of atmospheric phenomena (e.g., El Niño/Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation). A rainfall frequency analysis was performed for the nonstationary annual series, and significant differences in the return levels urn:x-wiley:1093474X:media:jawr12488:jawr12488-math-0001 can be expected for the scenarios analyzed. The identification of areas that are more susceptible to changes in rainfall levels will improve water resource management plans in the country, and it is expected that these plans will take into account nonstationary theory.
Modelación numérica de flujo mixto en conductos cerrados con esquemas en volúmenes finitos
Tecnología y Ciencias del Agua
José Luis Aragón Hernández 1 , Ernest Bladé 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Politécnica de Catalunya, Instituto de Investigación Flumen

Keywords: flujo en lámina libre, flujo en presión, flujo mixto, ranura de Preissmann, volúmenes finitos y colectores pluviales
Abstract: En este trabajo se presenta un modelo numérico para la simulación de flujo mixto (flujo en lámina libre y flujo en presión) en conductos cerrados a través de las ecuaciones de Saint Venant en una dimensión para flujo en lámina libre y con el método de la ranura de Preissmann para considerar el flujo en presión. Para la resolución de las ecuaciones se emplea el método de los volúmenes finitos con un esquema de alta resolución. El esquema utilizado es el método de Godunov con el Riemann solver de Roe de primer orden de precisión, más unas correcciones de segundo orden para obtener el esquema de alta resolución WAF-TVD. El flujo mixto es un fenómeno bastante común en colectores pluviales, túneles, tuberías de obras de toma de instalaciones hidroeléctricas, llenado/vaciado de tuberías, colectores de almacenamiento, etcétera. La entrada en carga en los conductos se puede generar desde el extremo aguas abajo, desde el extremo aguas arriba y por ambos extremos simultáneamente, siendo la primera la más común y, por lo tanto, la evaluada en este trabajo. Para demostrar la actuación del modelo, éste se aplica a un caso de referencia y a dos ensayos de laboratorio existentes en la literatura técnica. Los resultados obtenidos muestran que el modelo numérico es capaz de reproducir los experimentos con buena precisión. Con ello se demuestra que el modelo es idóneo para simular flujo en lámina libre en régimen lento, rápido y transcrítico (de lento a rápido y de rápido a lento), y flujo mixto.
Baseflow recession analysis in a large shale play: Climate variability and anthropogenic alterations mask effects of hydraulic fracturing
Journal of Hydrology
Saúl Arciniega Esparza 1 , José Agustín Breña Naranjo 1 , Antonio Hernández Espriú 2 , Adrián Pedrozo Acuña 1 , Bridget Scanlon 3 , Jean Philippe Nicot 3 , Michael Young 3 , Brad Wolaver 3 , Víctor Hugo Alcocer Yamanaka 4
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 The University of Texas at Austin, Jackson School of Geosciences
4 Comisión Nacional del Agua, Subdirección Técnica

Keywords: Hydraulic fracturing, Baseflow recessions, Drought, Texas
Abstract: Water resources development and landscape alteration exert marked impacts on water-cycle dynamics, including areas subjected to hydraulic fracturing (HF) for exploitation of unconventional oil and gas resources found in shale or tight sandstones. Here we apply a conceptual framework for linking baseflow analysis to changes in water demands from different sectors (e.g. oil/gas extraction, irrigation, and municipal consumption) and climatic variability in the semiarid Eagle Ford play in Texas, USA. We hypothesize that, in water-limited regions, baseflow (Qb) changes are partly due (along with climate variability) to groundwater abstraction. For a more realistic assessment, the analysis was conducted in two different sets of unregulated catchments, located outside and inside the Eagle Ford play. Three periods were considered in the analysis related to HF activities: pre-development (1980??2000), moderate (2001??2008) and intensive (2009??2015) periods. Results indicate that in the Eagle Ford play region, temporal changes in baseflow cannot be directly related to the increase in hydraulic fracturing. Instead, substantial baseflow declines during the intensive period of hydraulic fracturing represent the aggregated effects from the combination of: (1) a historical exceptional drought during 2011??2012; (2) increased groundwater-based irrigation; and (3) an intensive hydraulic fracturing activity.
Dynamic response of a poro-elastic soil to the action of long water waves: Determination of the maximum liquefaction depth as an eigenvalue problem
Applied Ocean Research
E. Arcos 1 , Eric Gustavo Bautista Godínez 2 , Federico Méndez Lavielle 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: Liquefaction depth, Long water waves, Eigenvalue problem, Poro-elastic soil
Abstract: In this work, a theoretical analysis of the dynamic response of a poro-elastic soil to the action of long water waves is conducted. For some combinations of the physical parameters of the soil and the water waves, the vertical stress tends towards zero at a certain unknown depth in the soil, as measured from the top of that medium. Under this condition, the liquefaction of the soil is imminent, at which time the excess pore pressure is essentially equal to the overburden soil pressure. Physical problems of this type have been widely studied in the specialized literature. However, most major studies have focused on solving the governing equations together with a liquefaction criterion. Here, the maximum momentary liquefaction depth induced by long water waves is considered as part of the problem, which is treated as an eigenvalue problem. To solve this problem, the governing equations are written in dimensionless form. The theoretical results show that for long waves, the horizontal displacements are smaller in magnitude than the vertical displacements, and when the wavelength or wave period increases, the maximum liquefaction also increases. Analytical solutions for the excess pore pressure and the horizontal and vertical displacements are obtained. The analytical results for the pore pressure are found to be very close to the analytical results reported in the specialized literature.
Digital color images ownership authentication via efficient and robust watermarking in a hybrid domain
Manuel Cedillo Hernández 1 , Antonio Cedillo Hernández 1 , Francisco Javier García Ugalde 2 , Mariko Nakano Miyatake 1 , Héctor Pérez Meana 1
1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Robust digital watermarking, ownership authentication, spread spectrum, discrete Fourier transform, discrete Contourlet transform
Abstract: We propose an efficient, imperceptible and highly robust digital watermarking scheme applied to color images for ownership authentication purposes. A hybrid domain for embedding the same watermark is used in this algorithm, which is composed by a couple of watermarking techniques based on spread spectrum and frequency domain. The visual quality is measured by three metrics called Peak Signal to Noise Ratio (PSNR), Structural Similarity Index (SSIM) and Visual Information Fidelity (VIF). The difference color between the original and watermarked image is computed using the Normalized Color Difference (NCD) measure. Experimentation shows that the proposed method provides high robustness against several geometric distortions including large image cropping, removal attacks, image replacement and affine transformation; signal processing operations including several image filtering, JPEG lossy compression, visual watermark added and noisy image, as well as combined distortions between all of them. Also, we present a comparison with some previously published methods which reported outstanding results and have a similar purpose as our proposal, i.e. they are focused in robust watermarking.
A New Method for Automated Detection of Diabetes from Heart Rate Signal
Journal of Mechanics in Medicine and Biology
Rajesh K. Tripathy 1 , Mario Roberto Arrieta Paternina 2 , Priyabrata Pattanaik 1
1 Siksha 'O' Anusandhan Deemed to be University, Faculty of Engineering and Technology
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Diabetes mellitus, heart rate signal, singular spectrum analysis, kernel sparse representation classifier, performance metrics
Abstract: Diabetes Mellitus (DM) is a chronic disease and it is characterized based on the increase in the sugar level in the blood. The other diseases such as the cardiomyopathy, neuropathy and retinopathy may occur due to the DM pathology. The RR-time series or heart rate (HR) signal quantifies the beat-to-beat variations in the electrocardiogram (ECG) and it has been widely used for the detection of various cardiac diseases. Detection of DM based on the features of HR signal is a challenging problem. This paper copes with a new method for the detection of Diabetes Mellitus (DM) based on the features extracted from the HR signal. The Singular Spectrum Analysis (SSA) of HR signal and the Kernel Sparse Representation Classifier (KSRC) are the mathematical foundations used to achieve the detection. SSA is used to decompose the HR signal into sub-signals, and diagnostic features such as the maximum value of each sub-signal and eigenvalues are evaluated. Then, the KSRC uses the proposed diagnostic features as inputs for detecting diabetes. The experimental results reveal that the proposal attains the accuracy, sensitivity, and specificity values of 92.18%, 93.75% and 90.62%, respectively, employing the KSRC and the hold-out cross-validation approach. The method is compared with existing approaches for detecting diabetes from HR signal.
A Separation Principle for Underactuated Lossless Lagrangian Systems
IEEE Transactions on Automatic Control
Sofía Ávila Becerril 1 , Antonio Loría 2 , Elena Panteley 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Centrale Supelec, Laboratoire des signaux et systemes

Keywords: Asymptotic stability, Robot kinematics, Closed loop systems, Manipulators, Observers, Velocity measurement
Abstract: We study under-actuated Lagrangian systems without dissipative forces, augmented by a chain of integrators. For such systems, we solve the open problem of global tracking control via position measurements only; strictly speaking, we establish uniform global asymptotic stability for the closed loop system. As a corollary, we obtain an original statement for flexible-joint robots, which closes a long-standing open problem of output feedback nonlinear control.
On the Robustness of a Passivity??based Controller for Microgrids
Sofía Ávila Becerril 1 , Diego Silva Martínez 1 , Gerardo Espinosa Pérez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Microgrids, Passivity Based Control, Control Droop
Abstract: Motivated by the growing interest on microgrids, in this paper, it is presented a numerical evaluation of some robustness properties of a previously reported passivity-based control law. The main feature of the approached controller is that, unlike commonly reported in the literature, dynamics of the power converters are included. Hence, a local control for the power converters is considered and complemented with a secondary control of the well-known droop type, where instead of measuring all the buses powers, as indicated in the original version of the microgrid controller, a state-estimation scheme is included to generate the information required by the former. The estimator allowed to incorporate measurement noise and showed the good performance of the controller in a more realistic scenario.
Comparison of the energetic performance of a binary cycle and a flash evaporation binary cycle, using low-enthalpy geothermal energy
International Journal of Sustainable Engineering
Héctor Miguel Aviña Jiménez 1 , Gabriel León De los Santos 2 , Miguel Ángel Benítez Torreblanca 1
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Binary cycle, low-enthalpy geothermal energy, sustainable power engineering and renewable energy technologies, renewable energy, engineering design for sustainable development
Abstract: In this article, the comparison of the energetic performance of a binary cycle and a modified binary cycle with flash evaporation is presented, both using a low-enthalpy geothermal resource. The comparative analysis is based on two main discourses: the first one evaluates a conventional binary cycle (CBC) with isopentane as working fluid in order to validate and compare the generated data with those reported in similar studies; the second one uses the same input parameters for both cycles, obtaining the cases in which the modified binary cycle is the most viable choice to use. In addition to the above, several aspects are considered when selecting the most suitable working fluid, and the use of water as working fluid is introduced. When the temperature of the geothermal resource is below 140 °C, and the ambient temperature is 25 °C, the flash evaporation binary cycle, using water as working fluid, shows an improved performance compared to a CBC, with a theoretical output over 1000 kWe. This may encourage new areas of opportunity for power generation, not only with low- and medium-enthalpy geothermal energy, but also with other renewable energy sources such as solar.
Enhancement of Corrosion Resistance of NiCrFeBSi Coatings Obtained by Flame Thermal Spray Process Adding an Electroless Nickel Coating Ni-P
Journal of Surface Engineered Materials and Advanced Technology
Arturo Barba Pingarrón 1 , Raúl Valdez Navarro 1 , Félix Sánchez De Jesús 2 , Ana María Bolarín Miró 2 , Jesús Rafael González Parra 1 , Alba Covelo Villar 1 , Miguel Ángel Hernández Gallegos 1 , Carlos Domínguez Ríos 3
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
3 Centro de Investigación en Materiales Avanzados

Keywords: Flame Thermal Spray Coatings, Electroless Nickel Plating, Duplex Coatings, Corrosion Resistance
Abstract: Flame Thermal Spray (FTS) coatings frequently show some porosity and reduced adherence to substrate, which affect its properties, especially its corrosion resistance. In this work, the corrosion resistance of AISI 1018 carbon steel coated by different methods is compared: electroless nickel (EN) coating, NiCrFeBSi obtained by FTS, duplex coatings of an EN deposit on a layer of NiCrFeBSi obtained by FTS and a layer of NiCrFeBSi on an EN deposit. The coatings were characterized using optical microscopy and scanning electron microscopy techniques, EDS microprobe microanalysis, roughness as well as electrochemical polarization tests to obtain the corrosion rate. The results show the enhancement in the corrosion resistance in saline medium of the duplex coatings, especially of the EN coating on FTS layer.
Una comparación de reducción de ruido en imágenes digitales utilizando un modelado estadístico de coeficientes wavelet y filtrado de Wiener
Revista Colombiana de Tecnologías de Avanzada
Francisco Javier García Ugalde 1 , Karina Ruby Pérez Daniel 1 , Laura Josefina Reyes Ruiz 1 , Manuel Cedillo Hernández 2 , Antonio Cedillo Hernández 2 , Mariko Nakano Miyatake 2 , Héctor Pérez Meana 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación

Keywords: Disminución de ruido en imágenes digitales, Transformada wavelet, Filtrado de Wiener
Abstract: Este trabajo presenta un método de disminución de ruido en imágenes digitales, basado en un enfoque Bayesiano de dos etapas con ajuste empírico. Se estiman los coeficientes de una transformada wavelet de la imagen donde se ha reducido el ruido, utilizando una estimación lineal con un criterio de minimización del error cuadrático medio. Estos coeficientes constituyen una estimación deseable de la varianza de los coeficientes wavelet de la imagen libre de ruido.
Soil Infiltration, Permeability, and Rock Fracturing Assessment to Establish Water Flow Patterns in a Mine with Acid Mine Drainage
Mine Water and the Environment
Ana Alejandrina Castro Rodríguez 1 , María Guadalupe Isidro Ángeles 1 , Angeles Neri Oliva 1 , Osvaldo Flores Castrellón 1 , Javier Arellano Gil 1 , José Enrique Santos Jallath 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Volumetric capacity, infiltrometer, constant-load permeameter, structural analysis, aquifer
Abstract: The flow of acid mine drainage (AMD) and neutral water were assessed inside an underground mine using a volumetric capacity technique, while water infiltration through the ground was assessed by performing three double ring constant load infiltrometer tests. Measured infiltration velocities were slow to moderate, between 0.036 and 2.07 cm/h. Total rainwater infiltration for the sub-basin was 0.031 hm3/yr. Tests performed on representative rock cores of the stratigraphical column of the area indicated that the permeabilities of the altered schist was 4.73E??10 cm/s, the tuff was 1.47E??09, and the graphitic phyllite was 2.47E??06. A structural analysis was performed inside the mine to assess fractures and faults using the mine plans for three different levels. Three major discontinuity paths were identified. Since the ground and rock permeabilities were low, the large water volumes inside the mine were attributed to these fractures. The results of this study are being used to understand flow patterns in the mine and to optimally locate a water treatment system to control the AMD.
Caracterización de los escenarios como herramienta para la planeación pública del agua: El caso mexicano
Gestión y Política Pública
Rita Victoria De León Ardón 1 , Gabriel De las Nieves Sánchez-Guerrero 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: caracterización de escenarios, planeación adaptativa del agua, escenarios, gobernanza colaborativa, characterization of scenarios, adaptive water planning, scenarios, collaborative governance
Abstract: El propósito de este artículo es determinar los rasgos característicos de los escenarios de agua utilizados en la gestión pública del agua en México. En la primera parte del artículo se hace un análisis de la problemática en la planeación del agua en México y en los escenarios en general. Posteriormente, se describe la evolución del concepto escenario, su uso dentro del paradigma de gobernanza colaborativa específicamente en la planeación adaptativa del agua. Por último, se presenta una caracterización de una muestra de escenarios del sector hídrico; la caracterización utiliza los cuatro factores clave de la planeación adaptativa del agua: enfoque sistémico, participación, información e innovación. La metodología incluye una matriz de caracterización, consulta a expertos y análisis de datos difuso.
On the stability of fractional neutron point kinetics (FNPK)
Applied Mathematical Modelling
Gilberto Espinosa Paredes 1 , Ricardo L. Cázares Ramírez 2 , Juan Luis François Lacouture 3 , Cecilia Martín del Campo 3
1 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
2 Universidad Autónoma Metropolitana, Unidad Iztapalapa
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Nuclear reactor, Fraction neutron point kinetics, Fractional stability, Anomalous diffusion, Transformation W-plane zero power transformer function
Abstract: The aim of this work is investigate the stability of fractional neutron point kinetics (FNPK). The method applied in this work considers the stability of FNPK as a linear fractional differential equation by transforming the s ?? plane to the W ?? plane. The FNPK equations is an approximation of the dynamics of the reactor that includes three new terms related to fractional derivatives, which are explored in this work with an aim to understand their effect in the system stability. Theoretical study of reactor dynamical systems plays a significant role in understanding the behavior of neutron density, which is important in the analysis of reactor safety. The fractional relaxation time (?α) for values of fractional-order derivative (α) were analyzed, and the minimum absolute phase was obtained in order to establish the stability of the system. The results show that nuclear reactor stability with FNPK is a function of the fractional relaxation time.
Study on the temperature distributions in fuel assemblies of lead-cooled fast reactors
International Journal of Nuclear Energy Science and Technology
Gilberto Espinosa Paredes 1 , Juan Luis François Lacouture 2 , Heriberto Sánchez Mora 2 , Alejandría D. Pérez Valseca 1 , Cecilia Martín del Campo 2
1 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: lead-cooled reactor, fast reactor, ELSY, annular fuel, fuel assembly, sub-channel analysis
Abstract: The aim of this paper is to make a comparative study of two concepts of Lead-Cooled Fast Reactor (LFR) fuel assemblies, from a point of view of the thermofluids performance. The sub-channel analysis approach was applied to determine the temperature distribution in the fuel, in the cladding and in the lead-coolant. The mathematical model is fully transient and takes into account the heat transfer in an annular fuel pellet design. The thermofluid is modelled with a mass, energy and momentum balance with thermal expansion effects. The neutronic processes are modelled with point kinetic equations for power generation with feedback fuel temperature and expansion effects. The numerical experiments consider steady-state and transient behaviours. The numerical comparison shows that a hexagonal assembly is an option to compact the size of the LFR core design. This option leads to higher temperature in the fuel and the cladding than in the case of a rectangular assembly design. Results show the LFR with square array is more sensitive to power changes than the hexagonal array at the same nominal power and with the same transient conditions.
Combined backstepping and HOSM control design for a class of nonlinear MIMO systems
International Journal of Robust and Nonlinear Control
Antonio Estrada 1 , Leonid Fridman Golredich 2 , Rafael Iriarte 2
1 Center for Engineering and Industrial Development
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: robust control, sliding modes, backstepping, uncertain systems
Abstract: This paper presents a control design algorithm that combines backstepping and high?order sliding modes. It is known that backstepping can achieve asymptotic stability for nonlinear systems in strict?feedback form in spite of parametric uncertainties. Nevertheless, when external perturbations are also present, only practical stability can be ensured. For the same aforementioned perturbed conditions, the combined design presented in this paper can achieve finite?time exact tracking/regulation. At the same time, the semi?global or global stability obtained through backstepping is preserved, and the gains of the high?order sliding modes controller can be reduced with respect to its direct application. The design is based on recently reported combined designs that are based on the idea of virtual controls, which can contain terms based on high?order sliding modes algorithms. The proposal also extends previous results to the multiple?input??multiple?output case.
High-order sliding-mode observer for linear time-varying systems with unknown inputs
International Journal of Robust and Nonlinear Control
Rosalba Galván Guerra 1 , Leonid Fridman Golredich 2 , Jorge Dávila Montoya 3
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación

Keywords: sliding modes, nonlinear observers, uncertain systems, linear time?varying system
Abstract: In this article, an observer for linear time variant systems affected by unknown inputs is suggested. The proposed observer combines the deterministic least squares filter and the high?order sliding?mode differentiator to provide exact state reconstruction in spite of bounded unknown inputs and system instability. The cascade structure of the algorithm provides a correct state reconstruction for the class of linear time variant systems that satisfy the structural property of strong observability. Simulations illustrate the performance of the proposed algorithm.
Fault-tolerant control with control allocation for linear time varying systems: an output integral sliding mode approach
IET Control Theory & Applications
Rosalba Galván Guerra 1 , Xinyi Liu 2 , Salah Laghrouche 3 , Leonid Fridman Golredich 4 , Maxime Wack 2
1 Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo
2 Université de technologie de Belfort Montbéliard (UTBM), Pôles et laboratoires de recherche
3 Universite Bourgogne Franche-Comté/UTBM,
4 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: closed loop systems, fault tolerant control, H?? control, linear systems, observers, robust control
Abstract: This study investigates the observer-based fault-tolerant control (FTC) problem for linear systems with multiple faults and external disturbances. Two novel types of FTC schemes are proposed, namely, the intermediate estimator-based parameter adjustment (IEBPA) FTC scheme, which deals with linear systems with matched disturbances and the intermediate estimator-based (IEB) H ?? FTC scheme, which is applicable to linear systems with mismatched disturbances. For the case with matched disturbances, it is shown that the IEBPA FTC scheme ensures the states of the closed-loop system to be uniformly ultimately bounded with an explicit bound. For the case with mismatched disturbances, it is proved that the IEB H ?? FTC scheme guarantees the closed-loop to be robustly stable with a prescribed H ?? performance index. A simulation example is given to illustrate the effectiveness of the proposed methods.
Evaluation of the Influence of Soil Density on Retention of Benzene and Light Petroleum Fractions
Nature Environment and Pollution Technology
Luis Antonio García Villanueva 1 , Georgina Fernández Villagómez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Benzene, bulk density, light petroleum fractions, mass balance, particle density
Abstract: The benzene and light petroleum fractions that were spilled during the life of the refinery were not remediated. Density is a physical property that is characteristic of soil and provides information on its porosity, aeration and infiltration capacity. Density is an important factor in determining the mass of contaminant present in the soil. The objective of this study was to evaluate the influence of soil density on the retention of benzene and light petroleum fractions. The results showed that the influence of soil density in determining the mass of a specific contaminant, by employing mass balance, is directly proportional to the density values that were used. When calculating mass with bulk density, the amount is lower than the amount obtained with real density. This observation is based on bulk density taking into account in the sample volume, the volume as a whole which includes pore volume. The volume of porous space is therefore reduced and accounts for an increase of the mass of contaminant found at that depth. It was possible to determine the influence of density of the soil in a real case, specifically for a large-size environmental liability, and to obtain suitable information on the mass of remaining contaminant after applying mass balance. The mass of contaminant that is obtained represents a proportional percentage of the value of the density as it increases, when taking bulk density as a reference. This finding is consistent with those that have been published in studies for columns, except this case was a study of an environmental liability instead of being a laboratory study.
Speech Synthesis in Mexican Spanish using LSP as Voice Parameterization
The Journal on Systemics, Cybernetics and Informatics
Carlos Franco Galván 1 , Abel Herrera Camacho 2 , Boris Escalante Ramírez 2
1 Benemérita Universidad Autónoma de Puebla
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Speech Synthesis, Linear Spectral Pair, HTS
Abstract: A voice parameterization using Linear Spectral was implemented to a Mexican Spanish HMM-based Speech Synthesis System. Five phrases were synthesized and statistically validated by applying a MOS test to 30 listeners who analyzed the original voices compared to a synthetic voice. Results were compared to previous work where MFCC was used as voice parameterization, the comparison shows that LSP parameterization is above the mean score and pointed better than MFCC.
Metal Insertion in a Methylamine-Functionalized Zirconium Metal??Organic Framework for Enhanced Carbon Dioxide Capture
Inorganic Chemistry
Ana Paulina Gómora Figueroa 1 , Jarad Mason 2 , Miguel González 2 , Eric Bloch 2 , Katie Meihaus 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 University of California, Berkeley, Department of Chemistry

Keywords: Anions, Amines, Adsorption, Cations, Materials
Abstract: The reaction of ZrCl4 with 2?,3?,5?,6?-tetramethylamino-p-terphenyl-4,4?-dicarboxylic acid (H2tpdc-4CH2NH2·3HCl) in the presence of NaF affords Zr6O4(OH)2.1F1.9(tpdc-4CH2NH2·3HCl)6 (1), which is a new member of the Zr6O4(OH)4(dicarboxylate linker)12 or UiO-68 family, and exhibits high porosity with BET and Langmuir surface areas of 1910 m2/g and 2220 m2/g, respectively. Remarkably, fluoride ion incorporation in the zirconium clusters results in increased thermal stability, marking the first example of enhancement in the stability of a UiO framework by this defect-restoration approach. Although material 1 features four alkylamine groups on each organic linker, the framework does not exhibit the high CO2 uptake that would be expected for reaction between CO2 and the amine groups to form carbamic acid or ammonium carbamate species. The absence of strong CO2 adsorption can likely be attributed to protonation at some of the amine sites and the presence of counterions. Indeed, exposure of material 1 to acetonitrile solutions of the organic bases 1,8-bis(dimethylamino)naphthalene (DMAN) or trimethylamine, affords a partially deprotonated material, which exhibits enhanced CO2 uptake. Exposure of basic amine sites also facilitates the postsynthetic chelation of copper(I) ([Cu(MeCN)4]·CF3SO3) to yield material 2 with an enhanced CO2 uptake of 4 wt % at 0.15 bar, which is double that of the parent framework 1.
Water Supply Source Evaluation in Unmanaged Aquifer Recharge Zones: The Mezquital Valley (Mexico) Case Study
Antonio Hernández Espriú 1 , Claudia Arango Galván 2 , Alfonso Reyes Pimentel 3 , Pedro Martínez Santos 4 , Carlos Pita De la Paz 5 , Sergio Macías Medrano 1 , Alberto Arias Paz 1 , José Agustín Breña Naranjo 6
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Geofísica
3 Comisión Nacional de Hidrocarburos
4 Universidad Complutense de Madrid, Facultad de Ciencias Geológicas
5 GEOTEM Ingeniería, S. A. de C. V.
6 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: aquifer, groundwater exploration, water supply, well logs, geophysical prospection, TDEM, pumping test, unmanaged recharge, wastewater irrigation, Mezquital Valley
Abstract: The Mezquital Valley (MV) hosts the largest unmanaged aquifer recharge scheme in the world. The metropolitan area of Mexico City discharges ~60 m3/s of raw wastewater into the valley, a substantial share of which infiltrates into the regional aquifer. In this work, we aim to develop a comprehensive approach, adapted from oil and gas reservoir modeling frameworks, to assess water supply sources located downgradient from unmanaged aquifer recharge zones. The methodology is demonstrated through its application to the Mezquital Valley region. Geological, geoelectrical, petrophysical and hydraulic information is combined into a 3D subsurface model and used to evaluate downgradient supply sources. Although hydrogeochemical variables are yet to be assessed, outcomes suggest that the newly-found groundwater sources may provide a long-term solution for water supply. Piezometric analyses based on 25-year records suggest that the MV is close to steady-state conditions. Thus, unmanaged recharge seems to have been regulating the groundwater balance for the last decades. The transition from unmanaged to managed recharge is expected to provide benefits to the MV inhabitants. It will also be likely to generate new uncertainties in relation to aquifer dynamics and downgradient systems.
Modelling the vulnerability of groundwater to contamination in an unconfined alluvial aquifer in Pakistan
Environmental Earth Sciences
Yawar Hussain 1 , Sadia Fida Ullah 2 , Muhammad B. Hussain 3 , Abdul Qayyum Aslam 4 , Gulraiz Akhter 5 , Hernán Martínez Carbajal 6 , Martín Cárdenas Soto 7
1 University of Brasilia, Department of Civil and Environmental Engineering
2 University of Brasilia, Institute of Biological Sciences
3 University of Lahore, Department of Physics
4 University of the Punjab, College of Earth and Environmental Sciences
5 Quaid-i-Azam, Department of Earth Sciences
6 Universidad Nacional de Colombia, Facultad de Minas
7 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: GIS, Indus Basin, DRASTIC, Hydrological stresses
Abstract: The area of Thal Doab is located in the Indus Basin and is underlain by a thick alluvial aquifer called the Thal Doab aquifer (TDA). The TDA is undergone intense hydrological stress owing to rapid population growth and excessive groundwater use for livestock and irrigated agricultural land uses. The potential impact of these land uses on groundwater quality was assessed using a DRASTIC model in a Geographic Information System environment. Seven DRASTIC thematic maps were developed at fixed scale and then combined into a groundwater vulnerability map. The resultant vulnerability index values were grouped into four zones as low, moderate, high and very high. The study has established that 76% of the land area that is underlain by the TDA has a high to very high vulnerability to groundwater contamination mainly because of a thin soil profile, a shallow water table and the presence of soils and sediments with high hydraulic conductivity values. In addition, only 2 and 22% of the total area lie in low and moderate vulnerability zones, respectively. The outcomes of this study can be used to improve the sustainability of the groundwater resource through proper land-use management.
Cost-benefit analysis to assess seismic mitigation options in Mexican public school buildings
Bulletin of Earthquake Engineering
Miguel A. Jaimes 1 , Mauro Niño Lázaro 2
1 Universidad Nacional Autónoma de México, Instituto de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cost-benefit analysis, schools, site effects, retrofitting, seismic risk
Abstract: This study presents a methodology to perform a cost-benefit (C/B) analysis to assess possible options such as retrofitting or reconstruction of structures focused on mitigation of direct physical losses due to seismic actions. The case of all public school buildings located in Mexico City is presented as an illustrative example having as measure parameters the expected loss, the expected annual loss (EAL) and the probable maximum loss (PML). For the proposed methodology the following steps are required: (1) To gather technical information of typical school buildings designed according to different past seismic codes of the region, (2) To propose seismic mitigation actions such as retrofitting or stiffening of the structural system in order to comply with the current Mexico City seismic design code (RCDF-2004), (3) To compute vulnerability functions by carrying out non-linear Incremental Dynamic Analyses (IDA) for the original designed structural systems and those modified according to the performed mitigation actions, (4) To carry out a probabilistic seismic risk analysis taking into account all locations of public school buildings in Mexico City, (5) To perform a C/B analysis assuming two different cases: (a) retrofitting and/or stiffening the structural system and (b) demolish and reconstruct a completely new school building. This analysis is carried out at two different levels: (1) vulnerability functions of structures considering the two mitigation actions are obtained and compared, and (b) a combination of the different mitigation alternatives is investigated in order to determine, by obtaining the EAL and PML, the number and location of schools that require mitigation actions assuming that economical resources are limited. The usefulness of carrying out a C/B analysis by computing the seismic risk is shown as an aid to formulate and define mitigation strategies that allow decision-makers to prioritize the use of the economic resources. The advantage of this approach is that the obtained results will be presented in such a way they will be easier to communicate to decision-makers even if they are not familiar with formal risk studies.
Trabecular bone modeling methodology using geometric representations
Ingeniería Investigación y Tecnología
Osvaldo Ruiz Cervantes 1 , José Salvador Lara Ramírez 1 , Edgar Isaac Ramírez Díaz 1 , Armando Ortiz Prado 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: cancellous bone, finite element software, trabecular structure, bone modeling
Abstract: In this paper is presented a methodology to generate two-dimensional models of cancellous bone from images, with the main objective to achieve a closer representation to reality, in terms of the geometries that can be obtained. The methodology mainly uses Python? language programming to establish instructions for using Abaqus? graphical tools and therefore automatically generate the trabecular structure from the original image. As a first step, each trabecula of the image is idealized as an ellipse and each one is taken as basis for generating the geometries of pores and trabeculae in the model. A simulation of a compression test is also presented for three models made with this methodology, where finite element software was used. It is concluded that the methodology allows getting a very similar trabecular structure to the real one.
Refractive index sensor based on photonic crystal fiber: effect of analyte channel diameter
Optical Engineering
María C. López Bautista 1 , Alexander Martynyuk 1 , Sergei Khotiaintsev 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Satellites, composites, waveguides, refractive index, sensors, waveguide modes, photonic crystal fibers
Abstract: We analyzed the resonant coupling in the low-refractive-index sensor based on a directional coupler implemented in a microstructured optical fiber with a composite core and the parallel analyte channel in the form of a hollow-core waveguide. We showed the possibility of an 8-fold increase in the analyte channel radius that is equivalent to a 64-fold increase in its cross section, in comparison to the existing design. With an increase in the analyte channel radius, the resonance frequencies of the composite core mode and the satellite waveguide modes shift to longer wavelengths, while the dispersion curves of the high-order modes of the satellite waveguide tend to merge and their resonances become less pronounced than the resonances of the low-order modes. With an increase in the analyte channel radius from 2 to 16????μm, the sensor sensitivity increases by 40% and the detection limit becomes lower by a factor of 2. Such an increase in the analyte channel radius also eliminates the need in a high-pressure pump for filling the channel with analyte and thus makes this sensor much more practical than was previously thought.
Design of Hybrid Hydrostatic/Hydrodynamic Journal Bearings for Optimum Self-Compensation Under Misaligning External Loads
Journal of Tribology
L. F. Martínez Esparza 1 , Jaime Gonzalo Cervantes De Gortari 2 , Enrique Chicurel Uziel 3
1 Embry-Riddle Aeronautical University Worldwide, College of Aeronautics
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Bearing design, Bearings, Fluid friction, Hydrodynamic lubrication, Hydrostatic lubrication, Pressurized bearings, Viscosity
Abstract: A method to design hybrid hydrostatic/hydrodynamic journal bearings, with the criterion of optimized self-compensation under misaligning loads, is presented. An analysis considering laminar and turbulent flow of a Newtonian incompressible lubricant between the bearing and a misaligned shaft, with restricted lubricant supply to each recess, is discussed. The mathematical model considers the modified steady-state Reynolds lubrication equation, an exact function for the local bearing radial clearance with a misaligned shaft, the continuity integral??differential equations at the recess limits, and boundary conditions at the cavitation zone and outer limits. The finite-difference method was used, and a modular computer program was developed. The procedure follows a univariate search to determine the optimum size and position of recesses and therefore obtain the design with the maximum reactive moment under misaligning loads. A validation of the model was obtained comparing the results with experimental and calculated data from the literature. Results for a 4??+??4 LBP hybrid bearing design are presented.
Interfacial Electric Effects on a Non-Isothermal Electroosmotic Flow in a Microcapillary Tube Filled by Two Immiscible Fluids
Andrés Matías 1 , Federico Méndez Lavielle 1 , Oscar Eladio Bautista Godínez 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica

Keywords: power-law fluid, electroosmotic flow, immiscible fluids, non-isothermal, microcapillary, Maxwell stress
Abstract: In this work, a non-isothermal electroosmotic flow of two immiscible fluids within a uniform microcapillary is theoretically studied. It is considered that there is an annular layer of a non-Newtonian liquid, whose behavior follows the power-law model, adjacent to the inside wall of the capillary, which in turn surrounds an inner flow of a second conducting liquid that is driven by electroosmosis. The inner fluid flow exerts an interfacial force, dragging the annular fluid due to shear and Maxwell stresses at the interface between the two fluids. Because the Joule heating effect may be present in electroosmotic flow (EOF), temperature gradients can appear along the microcapillary, making the viscosity coefficients of both fluids and the electrical conductivity of the inner fluid temperature dependent. The above makes the variables of the flow field in both fluids, velocity, pressure, temperature and electric fields, coupled. An additional complexity of the mathematical model that describes the electroosmotic flow is the nonlinear character due to the rheological behavior of the surrounding fluid. Therefore, based on the lubrication theory approximation, the governing equations are nondimensionalized and simplified, and an asymptotic solution is determined using a regular perturbation technique by considering that the perturbation parameter is associated with changes in the viscosity by temperature effects. The principal results showed that the parameters that notably influence the flow field are the power-law index, an electrokinetic parameter (the ratio between the radius of the microchannel and the Debye length) and the competition between the consistency index of the non-Newtonian fluid and the viscosity of the conducting fluid. Additionally, the heat that is dissipated trough the external surface of the microchannel and the sensitivity of the viscosity to temperature changes play important roles, which modify the flow field.
Social housing retrofit: Improving energy efficiency and thermal comfort for the housing stock recovery in Mexico
Energy Procedia
Luis Eduardo Medrano Gómez 1 , Azucena Escobedo Izquierdo 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Social housing retrofit, indoor thermal comfort, energy efficiency, abandoned dwellings, U value
Abstract: Social housing in Mexico has been built without considering internal thermal comfort. This situation has forced people to live in adverse conditions, increase the use of air-conditioning systems for those who can afford it, or to abandon the houses looking for a better place. Currently Mexico has nearly five million abandoned dwellings and 40% of built housing deficit requires expansion and/or improvement. Retrofit of existing buildings has been carried out in the world to improve energy efficiency or to reduce green housing emissions; however, in Mexico retrofit is not widely applied and less in social housing. This paper proposes and applies in two case studies with hot, semi-humid climate a method to evaluate the improvement of indoor thermal comfort through enhancing envelopés U value. Finally, an economic analysis is conducted to assess retrofitting social housing with Mexican government programs funds.
Tracking of the iceberg created by the Nansen Ice Shelf collapse
International Journal of Remote Sensing
Miguel Moctezuma Flores 1 , Flavio Parmiggiani 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Institute of Atmospheric Sciences and Climate, Bologna

Abstract: This article presents an analysis of the drifting path of one of the two giant icebergs created from the Nansen Ice Shelf (NIS) collapse of 7 April 2016. The study was carried out using synthetic aperture radar (SAR) images of Sentinel-1 satellite. Six SAR images, captured after the collapse from 9 April to 12 May, were retrieved from the European Space Agency Scientific Data Hub and remapped onto an equidistant cylindrical projection. A processing scheme was implemented which consists of the following steps: (1) speckle filtering, (2) binary segmentation, and (3) iceberg centroid detection. The final result is the tracking of the iceberg, with its relative velocity, at the different time intervals.
Synthetic aperture radar analysis of floating ice at Terra Nova Bay??an application to ice eddy parameter extraction
Journal of Applied Remote Sensing
Miguel Moctezuma Flores 1 , Flavio Parmiggiani 2 , Corrado Fragiacomo 3 , Lorenzo Guerrieri 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Institute of Atmospheric Sciences and Climate, Bologna
3 Instituo Nazionale di Oceanografia e di Geofisica Sperimentale

Keywords: Synthetic aperture radar, image segmentation, statistical analysis, correlation function, image acquisition, image processing, inspection
Abstract: In the framework of a study of ice formation in Antarctica, synthetic aperture radar (SAR) image acquisitions were planned over Terra Nova Bay (TNB). Thanks to the European Space Agency (ESA) Third Party Mission program, Cosmo-SkyMed and Radarsat-2 images over TNB were obtained for the period of February 20 to March 20, 2015; in addition, available Sentinel-1 images for the same period were retrieved from the ESA scientific data hub. The first inspection of the images revealed the presence of a prominent eddy, i.e., an ice vortex presumably caused by the wind blowing from the continent. The important parameters of an eddy are its area and lifetime. While the eddy lifetime was easily obtained from the image sequence, the area was measured using a specific processing scheme that consists of nonlinear filtering and Markov random field segmentation. The main goal of our study was to develop a segmentation scheme to detect and measure "objects? in SAR images. In addition, the connection between eddy area and wind field was investigated using parametric and nonparametric correlation functions; statistically significant correlation values were obtained in the analyzed period. After March 15, a powerful katabatic wind completely disrupted the surface eddy.
Data Clustering: An Approach for Evaluating the Adequate Number of Groups in Partitioned Techniques
Journal of Computer Science and Information Technology
Guillermo Molero Castillo 1 , Yaimara Céspedes González 2 , Alejandro Velázquez Mena 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Veracruzana

Keywords: Clustering, data mining, k-means, groups number, validation indexes
Abstract: The partitioned clustering techniques, such as k-means, have advantages in applications involving a large amount of data, but a particularity of this type of clustering is to establish a priori the number of input groups (k). So in practice, it is necessary to repeat the test by establishing different numbers of groups, choosing the solution that best suits the objective of the problem. Therefore, to validate the results obtained it is necessary to have validation mechanisms that allow evaluating the formation of the groups appropriately. An evaluation strategy is through validation indexes that help determine if the formation of the groups is adequate. These methods are based on estimates that identify how compact or separate the formed groups are. This paper presents validation indexes used as a strategy to determine the number of relevant groups. The results obtained indicate that this evaluation approach guarantees an adequate way the determination of the desired number of groups.
Influence of a tapered and slender wave collector on the increment of the efficiency of an oscillating water column wave-energy converter
Ocean Engineering
A. Mora 1 , Eric Gustavo Bautista Godínez 2 , Federico Méndez Lavielle 3
1 Tecnológico de Estudios Superiores de Ecatepec
2 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Numerical solution, Oscillating water column, Reynolds transport theorem, Wave amplification, Wave collector, WKB perturbation technique
Abstract: The objective of this work is to analyze the effect of a tapered and slender wave collector, which follows a power law distribution, on the increment of the useful power and the efficiency of an oscillating water column wave-energy converter. The governing equations are solved by a numerical procedure. The forced motion of the oscillating water column by the linear long water waves is modeled via the implementation of a well-known energy equation. Applying the Reynolds transport theorem to the first law of thermodynamics, a conjugated hydrodynamic model of the gauge pressure in the open air chamber and the oscillating water column is derived. An asymptotic solution for the elevation of the water waves in the wave collector is obtained. The results show that compared with a system without a tapered wave collector, the tapered wave collector improves the capture efficiency and increases the useful power of the oscillating water column. The results suggest that large values of the oscillating water column can be obtained near resonance, a condition reached by the increment of the immersion of the front wall of the device for a fixed wavelength. The numerical solution is compared with the analytical solution of a linear oscillator.
Development of an Epithelial Potential Difference Reading Device for Anomaly Detection in Breast
International Journal of Electronics Communication and Computer Engineering (IJECCE)
Fátima Moumtadi 1 , Sergio Meléndez Armas 1 , Jorge Luis Naude De la Llave 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Bio Potentials, Breast Tumors, Electric Potential, Epithelial Potential Difference, Signal Acquisition
Abstract: This article exposes the development of a device to acquire the potential differences in 1 the epithelial surface of the female breast, using an array of 24 electrodes distributed on the surface 2 of the breast, a signal acquisition board capable to take a reading range of 31.25mV to 1.024V to 3 potential differences in the epithelial surface of the breast and a graphical user interface developed 4 in Matlab®; with what we were able to get a platform to carry out more research into the mode of epithelial potential differences. The device was evaluated with 4 healthy Mexican women who were subject to a prior ultrasound exam or mammography. As a result, of the medical trial, we found different factors that can affect accurate measurement of the breast surface and obtained information about the various stages that contains a device measuring epithelial potential differences found in this region of the human body.
Fractional order model reference adaptive control for anesthesia
International Journal of Adaptive Control and Signal Processing
Gerardo Navarro Guerrero 1 , Yu Tang Xu 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: anesthesia, Barbalat lemma, fractional calculus, model reference adaptive control
Abstract: The design of a fractional order model reference adaptive control for anesthesia based on a fractional order model is proposed in the paper. This model gets around many difficulties in controller designs based on the pharmacokinetic/pharmacodynamic model, commonly used for anesthesia for theses purposes, and allows to design a simple adaptive controller with stability and positivity of the system ensured via Lyapunov analysis. Also, the convergence of the tracking error to zero is established by applying an extension of the Barbalat lemma, proven in the paper. Simulations illustrate the effectiveness and robustness of the proposed control.
Global and exact HOSM differentiator with dynamic gains for output-feedback sliding mode control
Tiago Roux Oliveira 1 , Antonio Estrada 2 , Leonid Fridman Golredich 3
1 State University of Rio de Janeiro, Department of Electronics and Telecommunication Engineering
2 Center for Engineering and Industrial Development
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Variable structure, Higher-order sliding modes, Differentiators, Output-feedback, Exact tracking, Global stability
Abstract: In this paper we introduce a global differentiator based on higher-order sliding modes (HOSM) and dynamic gains to solve the problem of trajectory tracking via output-feedback for a class of uncertain nonlinear plants with arbitrary relative degree and disturbances. Norm observers for the unmeasured state are employed to dominate the disturbances as well as to adapt the gains of the proposed differentiator since the nonlinearities may be state-dependent and time-varying. Uniform global stability and robust exact tracking are guaranteed employing the proposed HOSM based exact differentiator. The obtained results are not restricted to first-order sliding mode control feedback, but applies for second order sliding mode algorithms (twisting, super-twisting and variable gain super-twisting) as well as quasi-continuous HOSM finite-time controllers. Simulations with an aircraft pitch-control application illustrate the claimed properties, even in the presence of measurement noise.
Left ventricle Hermite-based segmentation
Computers in Biology and Medicine
Jimena Olveres 1 , Rodrigo Nava 2 , Boris Escalante Ramírez 3 , Enrique Vallejo Venegas 4 , Jan Kybic 2
1 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas
2 Czech Technical University, Faculty of Electrical Engineering
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería
4 Centro Médico ABC, Cardiología

Keywords: Active shape models, Level sets, Steered Hermite transform, Left ventricle segmentation, Local binary patterns, Ray Feature error
Abstract: In recent years, computed tomography (CT) has become a standard technique in cardiac imaging because it provides detailed information that may facilitate the diagnosis of the conditions that interfere with correct heart function. However, CT-based cardiac diagnosis requires manual segmentation of heart cavities, which is a difficult and time-consuming task. Thus, in this paper, we propose a novel technique to segment endocardium and epicardium boundaries based on a 2D approach. The proposal computes relevant information of the left ventricle and its adjacent structures using the Hermite transform. The novelty of the work is that the information is combined with active shape models and level sets to improve the segmentation. Our database consists of mid-third slices selected from 28 volumes manually segmented by expert physicians. The segmentation is assessed using Dice coefficient and Hausdorff distance. In addition, we introduce a novel metric called Ray Feature error to evaluate our method. The results show that the proposal accurately discriminates cardiac tissue. Thus, it may be a useful tool for supporting heart disease diagnosis and tailoring treatments.
A texture?based region growing algorithm for volume extraction in seismic data
Geophysical Prospecting
M. G. Orozco del Castilllo 1 , Martín Cárdenas Soto 2 , C. Ortiz Alemán 1 , C. Couder Castañeda 3 , Jaime Urrutia Fucugauchi 4 , A. Trujillo Alcántara 1
1 Instituto Mexicano del Petróleo
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Politécnico Nacional, Centro de Desarrollo Aeroespacial
4 Universidad Nacional Autónoma de México, Instituto de Geofísica

Keywords: Salt bodies, Genetic algorithms, Principal component analysis, Seismic textures, Statistical tests, Seeded?based region growing, seismic textures
Abstract: We present a novel approach to automated volume extraction in seismic data and apply it to the detection of allochthonous salt bodies. Using a genetic algorithm, we determine the optimal size of volume elements that statistically, according to the U?test, best characterize the contrast between the textures inside and outside of the salt bodies through a principal component analysis approach. This information was used to implement a seeded region growing algorithm to directly extract the bodies from the cube of seismic amplitudes. We present the resulting three?dimensional bodies and compare our final results to those of an interpreter, showing encouraging results.
Recimentación y hundimiento inducido de un edificio industrial mediante uso de pilotes de control y extracción de material
Hormigón y Acero
Bernardo Orozco Rivas 1 , Mabel Mendoza Pérez 2
1 Fábrica de Jabón La Corona
2 Universidad Nacional Autónoma de México, Facultad de Ingenierían

Keywords: Reparación de cimentación, hundimiento inducido, extracción de material, pilotes de fricción, pilotes de control
Abstract: Se presenta el caso de la reparación y hundimiento inducido de la cimentación de un edificio industrial de acero, cuya cimentación consiste en zapatas aisladas y pilotes de fricción, ubicado en una zona sísmica y de grandes hundimientos en México. El procedimiento de reparación consistió en la construcción de una celda de hormigón armado para convertir los pilotes de fricción a pilotes de control y además permitir la extracción de material por debajo de la cimentación, logrando que el edificio siga el hundimiento regional. Mediante este proceso el edificio asentó 0,27m. Durante los trabajos ocurrieron 2 sismos de magnitudes 6,6 y 5,4, respectivamente, y en ninguno de ellos se detectó daño o mal funcionamiento del sistema, manteniendo en todo momento la seguridad del personal, de la estructura y el tránsito de vehículos.
2D?ERT Survey for the Identification of Archaeological and Historical Structures beneath the Plaza of Santo Domingo, Mexico City, Mexico
Archaeological Prospection
Pedro Paz Arellano 1 , Andrés Tejero Andrade 2 , Denisse L. Argote Espino 3
1 Instituto Nacional de Antropología e Historia, Coordinación Nacional de Monumentos Históricos
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Nacional de Antropología e Historia, Dirección de Estudios Arqueológicos

Keywords: 2D electrical tomography, historical site, urban environment, archaeological structure, Plaza of Santo Domingo, Mexico City
Abstract: Santo Domingo public square (Plaza of Santo Domingo) is located in Mexico City's downtown area. The history of its transformations began in pre?Hispanic times and is still being written. The objectives of this investigation were to establish the position of the northwest corner of the ancient Mexica wall and to determine whether the Plaza became a public square during pre?Hispanic or colonial times, taking into account the contradictions of the historical sources. For this purpose, we implemented three 80?m?long electrical resistivity tomography (ERT) profiles in the Plaza and one on the eastern side of the Church of Santo Domingo de Guzmán. A Wenner??Schulmberger array was designed for the data acquisition. The results could support the hypothesis that the Plaza of Santo Domingo was designed and constructed as an open public area in colonial times, since the observations in the electric profiles beneath the square could reveal the presence of a pre?Hispanic structure. This structure could be part of the wall that surrounded the Mexica ceremonial compound. At the eastern side of the Dominican church, the foundations of the first Spanish chapel were identified, as well as portions of modern concrete deposits injected into the subsoil to stabilize the constant subsidence of the building.
Mechanically assisted synthesis of multiferroic BiFeO3: Effect of synthesis parameters
Journal of Alloys and Compounds
Fernando Pedro García 1 , Félix Sánchez De Jesús 1 , Claudia Alicia Cortés Escobedo 2 , Arturo Barba Pingarrón 3 , Ana María Bolarín Miró 1
1 Universidad Autónoma del Estado de Hidalgo, Área Académica de Ciencias de la Tierra y Materiales
2 Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: High-energy ball milling, Bismuth ferrite, BiFeO3, Mechanochemical processing, Multiferroic
Abstract: We report the influence of synthesis parameters on the crystal structure and the electronic and magnetic behavior of multiferroic bismuth ferrites, BiFeO3, synthesized by high-energy ball milling followed by annealing at low temperatures. Mixtures of Fe2O3 and Bi2O3, in a stoichiometric ratio, were mixed and milled for different durations from 0 to 13 h in an ambient air atmosphere and annealed for 2 h at different temperatures, from 350 to 750 °C in order to obtain BiFeO3. X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the synthesis parameters. The results showed that BiFeO3 particles with mostly a single phase (?98 wt%) were fabricated by the assisted high-energy ball milling process, after 5 h of milling followed by heat treatment at 650 °C; higher milling durations and annealing temperatures promote perovskite decomposition. The obtained powder shows a weak ferromagnetic behavior, which changes to an antiferromagnetic order when the powder is pressed at 900 MPa and sintered at 800 °C for 2h. The magnetic and dielectric results confirm the multiferroic behavior of the obtained material.
Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials
Fluid Dynamics Research
M. Peralta 1 , José Carlos Arcos Hernández 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters ${R}_{\omega }$, ${R}_{\zeta }$, and $\bar{\kappa }$, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.
On the adaptive control of cooperative robots with time?variant holonomic constraints
International Journal of Adaptive Control and Signal Processing
Javier Pliego Jiménez 1 , Marco Antonio Arteaga Pérez 2
1 CICESE, División de Física Aplicada
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: adaptive control, cooperative robots, force control, holonomic constraints
Abstract: In this work, we consider the problem of 2 robots handling a rigid object, while model?parameter uncertainties are assumed. It is also assumed that the manipulators can push but not pull the object. Several control schemes proposed in the literature attempt to control the position of the object rather than its orientation. However, many industrial tasks require to move and to rotate the object. To this end, we propose an adaptive hybrid position/force control law based on time?variant holonomic constraints, which allow for object position and orientation control. Our approach guarantees that the force error asymptotically converges to 0; therefore, a stable grasp can be accomplished by means of a proper definition of the desired pushing force. In addition, a dynamic model of the cooperative system based on the load distribution and joint?space orthogonalization principles is developed. Experimental results are presented to validate the proposed dynamic model and control scheme.
Heterogeneous model for heat transfer in Green Roof Systems
Energy and Buildings
Sergio Quezada García 1 , Gilberto Espinosa Paredes 2 , Azucena Escobedo Izquierdo 1 , Alejandro Vázquez Rodríguez 3 , R. Vázquez Rodríguez 2 , J. J. Ambríz García 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Autónoma Metropolitana, Área de Ingeniería en Recursos Energéticos
3 Universidad Autónoma Metropolitana, Unidad Iztapalapa

Keywords: Green roof, Mathematical model, Heat transfer, Heterogeneous media
Abstract: Due to the many benefits offered by Green Roofs Systems (GRS), such as: energy savings in buildings and reducing urban heat island, to mention some, these have been extensively studied in recent years. Many theoretical and experimental studies have been conducted to determine the potential of the GRS as passive cooling systems in buildings. However, most of the experimental studies are applicable only to GRS in question and the existing mathematical models to predict the heat flux, through the various layers of biotic and abiotic materials that make up the GRS, assume that these layers are formed by homogeneous materials and not consider that these may be heterogeneous media. In this work is considered that some of the layers that make up GRS are heterogeneous, as the green layer is formed by plants and air or the substrate layer is formed by land and water; thus, a heat transfer model for GRS is proposed that consider biphasic media, and non-conventional boundary condition for coupling the GRS layers are proposed; this model allows further study of heat transfer through heterogeneous media, especially in GRS. The model is verified with data published and experimental data obtained in the Controlled Environment Laboratory of the Universidad Autónoma Metropolitana-Iztapalapa.
Experimental validation and effect of modelling assumptions in the hierarchical multi-scale simulation of the cup drawing of AA6016 sheets
Modelling and Simulation in Materials Science and Engineering
M. A. Ramírez 1 , Rafael Schouwenaars Franssens 1 , P. Eyckens 2 , J. Gaward 3 , Leo Kestens 4 , A. Van Bael 2 , P. Van Houtte 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 KU Leuven, Department of Materials Engineering
3 KU Leuven, Department of Computer Science
4 Ghent University, EEMMeCS Department

Keywords: hierarchical multiscale model, modelling, aluminium
Abstract: An essential step in the improvement of design strategies for a wide range of industrial deep drawing applications is the development of methods which allow for the precise prediction of shape and processing parameters. Earlier work has demonstrated, in a clear but qualitative manner, the capabilities of the hierarchical multiscale (HMS) model, which predicts the anisotropic plastic properties of metallic materials based on a statistical analysis of microstructure-based anisotropy and a continuous description of the yield locus. The method is implemented into the ABAQUS finite-element software but, until recently, little attention had been paid to other factors which determine the accuracy of a finite element prediction in general, such as mesh size, friction coefficient and rigid/elastic modelling of the tools. Through the analysis of cup drawing, which is a well-established laboratory-scale test relevant to industrial applications, a quantitative comparison is provided between measured cup geometry and punch force and modelling results for commercial AA6016T4 aluminium sheets. The relatively weak earing behaviour of these materials serves to emphasise the small differences still found between model and experiment, which may be addressed by future refinement of the micromechanical component of the HMS. Average cup height and punch force, which is an important process parameter omitted in earlier studies, depend primarily on the friction coefficient and assumptions in the modelling of the tools. Considering the balance between accuracy and precision, it is concluded that the proposed methodology has matured sufficiently to be used as a design tool at industrial level.
Fault detection and isolation for nonlinear non-affine uncertain systems via sliding-mode techniques
International Journal of Control
Héctor Ríos 1 , E. Punta 2 , Leonid Fridman Golredich 3
1 INRIA Lille - Nord Europe, Parc Scientifique de la Haute Borne
2 Politecnico di Torino, CNR-IEIIT
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Fault detection and isolation, nonlinear systems, non-affine systems, sliding-modes
Abstract: This paper considers the fault detection and isolation problem for nonlinear uncertain non-affine systems. The proposed approach is based on an output-feedback stabilisation strategy, which exploits a Luenberger-like nonlinear observer. As a main result, a residual-based fault detection and isolation approach is developed, which relies on the measurable output, some of its derivatives, which are provided exactly by a uniform high-order sliding-mode differentiator, and the observer??s state. The proposed methodology is able to detect some possible components and actuators faults, and to isolate, under some mild conditions, the actuator faults from those ones in components. Simulation results illustrate the feasibility of the proposed approach.
On the design of GaN Chireix power amplifiers using an embedding device model
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields
Patrick Roblin 1 , Chang Hsiu Chen 1 , Francisco Javier Martínez Rodríguez 2 , Chenggang Xie 3 , José Ismael Martínez López 2
1 The Ohio State University, Department of Electrical and Computer Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Rockwell Collins

Keywords: GaN HEMTs, nonlinear embedding, embedding device model, PA design
Abstract: As wireless cellular communication keeps expanding toward higher bandwidth, multiband signals, and high frequencies of operation, the design of power efficient radio frequency power amplifiers (PAs) for cellular phone basestations is submitted to more stringent requirements. This paper discusses the promising technique of nonlinear embedding, which may help stream line the design of such PAs. To this order, the design of a GaN radio frequency PA from device modeling to circuit design is presented. The large signal modeling of GaN high?electron?mobility transistors including thermal and trapping memory effects is discussed first. The nonlinear embedding device model is then introduced using the concept of an anti?circuit transfer network. This embedding device model is then applied to the design of a Chireix amplifier. New Chireix design equations are developed to work with the memoryless inner core of the embedding device model, and their validity is confirmed in circuit simulations. The Chireix amplifier is then designed using the multi?harmonic impedance terminations predicted by the embedding device model for the package reference planes. Finally, the resulting Chireix amplifier is implemented in a circuit simulator with the original GaN high?electron?mobility transistors device model and verified in simulations to have a performance approaching that of the originally targeted Chireix at the current reference planes. These theoretical and simulation results demonstrate the potential of the nonlinear embedding PA design technique in the design of Chireix power amplifiers.
Pulsatile electroosmotic flow in a microcapillary with the slip boundary condition
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Guillermo Rojas 1 , José Carlos Arcos Hernández 1 , M. Peralta 1 , Federico Méndez Lavielle 2 , Oscar Eladio Bautista Godínez 1
1 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica y Eléctrica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Transient electroosmotic flow, Microcapillary, Slip boundary condition, Pulsatile electroosmotic flow, High zeta potential
Abstract: The pulsatile electroosmotic flow (PEOF) of a Newtonian fluid in a circular microchannel with slippage at the surface is theoretically analyzed. It is assumed that the electroosmotic flow is started from rest by the sudden imposition of a time-dependent external electric field. The PEOF is controlled by the following dimensionless parameters: the normalized slip length, Δ, defined as the ratio of the Navier length to the microcapillary radius; the angular Reynolds number, Rω, which quantifies the competition between the time scale for the diffusion of momentum across the microcapillary and the externally imposed time scale due to the oscillatory electric field; the parameter ?, which characterizes the amplitude of the oscillating electric field; the electrokinetic parameter , defined as the ratio of the characteristic length scale to the Debye length; and the ionic energy parameter, α, which compares the electric potential at the surface to the thermal potential. The analysis is conducted for low and high zeta potentials; in the former case, an analytical solution is obtained, whereas in the latter, a numerical solution is found. The results reveal that the volumetric flow rate is notably increased in a microchannel with slippage at the wall surface.
Chattering Analysis of HOSM Controlled Systems: Frequency Domain Approach
IEEE Transactions on Automatic Control
Antonio Rosales 1 , Yuri Shtessel 1 , Leonid Fridman Golredich 2 , Chandrasekhara Bharath Panathula 1
1 The University of Alabama, Department of Electrical and Computer Engineering
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Frequency-domain analysis, Algorithm design and analysis, Stability analysis, Heuristic algorithms, Prediction algorithms, Limit-cycles, Control systems
Abstract: In this article, a methodology of chattering analysis of Sliding Mode/Higher Order Sliding Mode (SM/HOSM) control systems in the frequency domain is presented. A numerical method for computing the Describing Functions (DFs) of HOSM control algorithms is given. The algorithm for predicted chattering parameters in dynamically perturbed system via the Describing Function-Harmonic Balance (DF-HB) technique is proposed. The stability conditions for limit cycles in dynamically perturbed HOSM control systems are presented. The concepts of Practical Stability Phase Margin (PSPM) and Practical Stability Gain Margin (PSGM) as the robustness metrics to unmodeled dynamics in HOSM control systems are introduced. The methodologies for computing PSPM and PSGM via DF-HB technique are provided. The accuracy of the proposed chattering analysis techniques is confirmed via computer simulations.
Experimental study on laminar flow over two confined isothermal cylinders in tandem during mixed convection
International Journal of Thermal Sciences
Erick Salcedo 1 , César Treviño 2 , Carlos Alberto Palacios Morales 1 , Roberto Zenit 3 , Lorenzo Martínez Suástegui 4
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Facultad de Ciencias
3 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales
4 Instituto Politécnico Nacional, Escuela Superior de Ingeniería Mecánica

Keywords: Tandem cylinders, Vortex shedding, Blockage ratio, Interference effects, PIV, Wall effects
Abstract: An experimental investigation of laminar aiding and opposing mixed convection is carried out using particle image velocimetry (PIV) to assess the thermal effects on the wake of two isothermal cylinders of equal diameter in tandem array placed horizontally and confined inside a vertical closed-loop downward rectangular water channel. The buoyancy effect on the flow distributions are revealed for flow conditions with Reynolds number based on cylinder diameter of Re = 100 and 200, blockage ratio of BR = D/H = 0.3, aspect ratio of AR = W/D = 5, pitch-to-diameter ratio of s = L/D = 3, and values of the buoyancy parameter (Richardson number) in the range -1
Improving force tracking control performance in cooperative robots
International Journal of Advanced Robotic Systems
Pablo Sánchez Sánchez 1 , Marco Antonio Arteaga Pérez 2
1 Benemérita Universidad Autónoma de Puebla, Facultad de Electrónica
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Cooperative robots, principle of orthogonalization, design a velocity observer, saturated function, hyperbolic tangent function, force tracking, control performance
Abstract: In order to obtain the environment??s information, cooperative robots could need a lot of sensors. A possible solution to reduce the number of sensors might be the use of control??observer structures. In this article, we have designed a control algorithm by using a modified hybrid computed torque method based on the principle of orthogonalization, but in order to avoid the use of tachometers in the implementation, we are including a velocity observer. The stability proof is developed by using the theory of Lyapunov. Simulation of the proposed control structure compared with a well-known control structure via the performance index analysis is presented. Experimental tests are implemented with the control structure that has the best performance index.
Automated Classification of Severity in Cardiac Dyssynchrony Merging Clinical Data and Mechanical Descriptors
Computational and Mathematical Methods in Medicine
Alejandro Santos Diaz 1 , Raquel Valdés Cristerna 2 , Enrique Vallejo Venegas 3 , Salvador Hernández 4 , Luis Jiménez Ángeles 5
1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Departamento de Bioingeniería
2 Universidad Autónoma Metropolitana, Departamento de Ingeniería Eléctrica
3 Centro Médico ABC, Cardiología
4 Instituto Naiconal de Cardiología "Ignacio Chávez""", Departamento de Cardiología Nuclear
5 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Cardiac resynchronization therapy (CRT) improves functional classification among patients with left ventricle malfunction and ventricular electric conduction disorders. However, a high percentage of subjects under CRT (20%??30%) do not show any improvement. Nonetheless the presence of mechanical contraction dyssynchrony in ventricles has been proposed as an indicator of CRT response. This work proposes an automated classification model of severity in ventricular contraction dyssynchrony. The model includes clinical data such as left ventricular ejection fraction (LVEF), QRS and P-R intervals, and the 3 most significant factors extracted from the factor analysis of dynamic structures applied to a set of equilibrium radionuclide angiography images representing the mechanical behavior of cardiac contraction. A control group of 33 normal volunteers ( years, LVEF of ) and a HF group of 42 subjects ( years, LVEF < 35%) were studied. The proposed classifiers had hit rates of 90%, 50%, and 80% to distinguish between absent, mild, and moderate-severe interventricular dyssynchrony, respectively. For intraventricular dyssynchrony, hit rates of 100%, 50%, and 90% were observed distinguishing between absent, mild, and moderate-severe, respectively. These results seem promising in using this automated method for clinical follow-up of patients undergoing CRT.
Spiraphase-type leaky-wave structure
Journal of Electromagnetic Waves and Applications
Daniel Seseña Martínez 1 , Jorge Rodríguez Cuevas 1 , José Ismael Martínez López 1 , Alexander Martynyuk 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Leaky-wave antenna, leaky wave, reflectarray, reconfigurable antenna
Abstract: A leaky-wave structure (LWS) based on two stacked spiraphase-type reflectarrays (RAs) is analysed in this paper. Each RA contains capacitively loaded ring slot elements arranged at the nodes of a square periodic grid. The proposed LWS performs frequency scanning of a conical beam by changing the cone aperture angle 2θ0. Furthermore, the reconfiguration of the radiation pattern can be achieved by rotating the RA elements. Four Ka-band LWSs with different angular positions of the capacitive loads at the top RA were designed, fabricated and tested to demonstrate the pattern reconfiguration capability. A full-wave mathematical model was used to optimize the reflectarray elements and a simplified mathematical model was developed to predict the radiation characteristics of the whole structure. It was experimentally proven that frequency sweep from 36.37 to 39.9 GHz leads to the change of the angle θ0 from 0° to 38°. The increment of θ0 from 0° to 23° at 36.4 GHz was observed, when the reactive loads of the ring-slot elements at the top RA were rotated on the angle 18°. Good agreement between theoretical predictions and measurements was observed.
Twisting sliding mode control with adaptation: Lyapunov design, methodology and application
Yuri Shtessel 1 , Jaime Alberto Moreno Pérez 2 , Leonid Fridman Golredich 3
1 The University of Alabama, Department of Electrical and Computer Engineering
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería
3 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Sliding mode control, Adaptive control
Abstract: A novel adaptive-gain twisting controller that is robust to the bounded disturbances with the unknown boundaries is proposed. The control algorithm is derived using the Lyapunov function technique. It is shown that an ideal or real second order sliding mode is established, and the adaptation algorithm does not overestimate the control gain. The efficacy of the proposed adaptive twisting control is experimentally verified on a mass??spring??damper system.
An LMI approach for second-order sliding set design using piecewise Lyapunov functions
Alan Tapia 1 , Miguel Bernal 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Sonora

Keywords: Sliding set, Piecewise, L^1, Lyapunov function, Linear matrix inequality
Abstract: This paper pursues recent results on second-order sliding set design for uncertain linear systems with matched uncertainties, a methodology that allows the designer to use a lesser number of derivatives; it is based on the direct Lyapunov method and its conditions are expressed as linear matrix inequalities, which are efficiently solved via convex optimization techniques. In contrast with former reports on this matter, the class of Lyapunov functions in this work is enlarged to the set of those which are piecewise L^1 , which naturally leads to design advantages as well as to a more natural adaptation of the Lyapunov function to the discontinuities arising in the sliding-set design methodology. Simulation examples are included to show the effectiveness of the proposed approach.
Nonlinear sliding mode control design: An LMI approach
Systems & Control Letters
Alan Tapia 1 , Miguel Bernal 2 , Leonid Fridman Golredich 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Instituto Tecnológico de Sonora

Keywords: Nonlinear sliding surface, Convex models, Linear matrix inequalities
Abstract: This paper presents a novel nonlinear sliding mode control methodology for systems with both matched and unmatched perturbations (including parametric uncertainties). Instead of traditional approaches where uncertainties and nonlinearities are coped with via linear nominal models and linear sliding surfaces, the proposed approach incorporates exact convex expressions to represent both the nonlinear surface and the system, thus allowing a significant chattering reduction. Moreover, thanks to the convex form of the nonlinear nominal model, when combined with the direct Lyapunov method, it leads to linear matrix inequalities, which are efficiently solved via convex optimization techniques. Illustrative examples are provided.
Design of Continuous Twisting Algorithm
Víctor Torres González 1 , Tonametl Sánchez 2 , Leonid Fridman Golredich 1 , Jaime Alberto Moreno Pérez 2
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería
2 Universidad Nacional Autónoma de México, Instituto de Ingeniería

Keywords: Sliding Mode control, Lyapunov function
Abstract: For the double integrator with matched Lipschitz disturbances we propose a continuous homogeneous controller providing finite-time stability of the origin. The disturbance is compensated exactly in finite time using a discontinuous function through an integral action. Since the controller is dynamic, the closed loop is a third order system that achieves a third order sliding mode in the steady state. The stability and robustness properties of the controller are proven using a smooth and homogeneous strict Lyapunov function (LF). In a first stage, the gains of the controller and the LF are designed using a method based on Pólya??s Theorem. In a second stage the controller??s gains are adjusted through a sum of squares representation of the LF.
Analysis and stiffness evaluation of a microparallel kinematic machine
Ricardo Yáñez Valdez 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: Isotropic behavior, micromanufacturing, microparallel kinematic machine, set-up prototype, stiffness maps
Abstract: This study explores a scaled version of a 3-PRRR parallel configuration that can be used in micro-machining tasks. The study addresses a stiffness model of a micro-parallel kinematic machine (mPKM) by employing an approach involving kinematic and static equations. The objective of the model includes providing an understanding of the manner in which the stiffness of a mechanism changes as a function of both the position of an end-effector and the estimated cutting forces that are generated by micro-machining operations. An experimental prototype is considered for the preliminary validation. Three work planes and three cutting directions into the workspace are evaluated by iso-stiffness mapping. The results indicate that the mPKM operates with high stiffness performances in static operations. This is useful for suitable improvements in the prototype and developing analytical design criteria.
Control Neuronal en Línea para Regulación y Seguimiento de Trayectorias de Posición para un Quadrotor
Revista Iberoamericana de Automática e Informática Industrial
Hugo Yáñez Badillo 1 , Rubén Tapia Olvera 2 , Omar Aguilar Mejía 3 , Francisco Beltrán Carbajal 4
1 Universidad Politécnica de Tulancingo, Departamento de Posgrado
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Universidad Popular Autónoma del Estado de Puebla, Departamento de Posgrados
4 Universidad Autónoma Metropolitana, Unidad Azcapotzalco

Keywords: Control Neuronal, Control Libre de Modelo, Aprendizaje Automático, Sistemas Subactuados
Abstract: Los sistemas de control automático día a día se han convertido en elementos importantes en la vida cotidiana, en tal sentido, se deben proponer nuevas y mejores formas de incorporar modelos matemáticos y algoritmos de control adaptativos para superar la gran cantidad de cambios técnicos y físicos a los que se enfrentan para su utilización. En este artículo se realiza el control de posición y seguimiento de trayectorias para un Quadrotor. Debido a la naturaleza no lineal de este sistema subactuado, se propone el empleo de un controlador adaptativo basado en redes neuronales B-spline que permita determinar las señales de control mediante un entrenamiento dividido en dos etapas: a) uno inicial fuera de línea y; b) uno continuo en línea. Esta forma de aprendizaje permite al Quadrotor extender un desempeño satisfactorio ante diferentes condiciones operativas y seguimiento de los valores de referencia. Los resultados de simulación verifican la aplicabilidad del controlador propuesto y el impacto que se tiene en el desempeño del sistema minimizando la necesidad de contar con un modelo matemático no lineal detallado, así como el conocimiento exacto de los valores de los parámetros del Quadrotor.
Policy proposal for metals speciation in tailings contaminated soils: A case study in Chihuahua, Mexico
Journal of the Mexican Chemical Society
Irma Cruz Gavilán García 1 , Georgina Fernández Villagómez 2 , Alejandro Menchaca Pérez 1 , Luis Adrián Barraza Torres 2 , Arturo Gavilán García 3
1 Universidad Nacional Autónoma de México, Facultad de Química
2 Universidad Nacional Autónoma de México, Facultad de Ingeniería
3 Instituto Nacional de Ecología y Cambio Climático

Keywords: Arsenic, lead, atomic absorption spectrometry, specia-tion, mining waste
Abstract: This work is focused in studying the inclusion of chemical speciation in the characterization of mining tailings in Mexican regulation with a case study in Parral, Chihuahua, Mexico. In this site, high concentration of lead and arsenic in tailings located in the surroundings represent a high concern to the local population. The total concentration of Pb in the samples ranged from 78.03 ± 2.67 to 5748 ± 263.63 [mg kg-1] and from 5.49 ± 0.43 to 509.84 ± 40.18 [mg kg-1] for As. Chemical speciation was tested for samples that exceeded the limits of the Mexican Regulation using sequential extractions proposed by the Bureau Community of Reference (BCR) to obtain the distribution of lead and arsenic in four different fractions. The set of extractions consisted in the extractable/exchangeable fraction (F1), the reducible fraction (F2), the metals bound to organic matter and sulfides (F3) those under oxidizing conditions, and the residual fraction (RF). The results show that 70% of lead is found in F1 and F2 fractions while 20% is found in F3 fraction. In case of arsenic, 60% is found in residual fraction, 25% in fraction F3 and less than 15% in fractions F1 and F2.
Applying Theoretical-Methodological Tools for the Implementation of ISO 9001: 2015 Clause 4 Context of the Organization
Management Studies
Antonia Navarro González 1 , Aida Huerta Barrientos 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: quality management system, ISO 9001, internal analysis, external analysis, methodology, stakeholders
Abstract: Nowadays, in order to satisfy the ISO 9001: 2015 requirements, organizations access to information from web sites, consultant guides, Internet forums, books, and courses, as a first approximation, however, the quality, reliability, validity, and accuracy of the information content in these is limited. The research topic of this study is the use of theoretical methodological tools, whose implementation supports the organizations in the fulfillment of requirement 4 of ISO 9001: 2015, adapting it to their particular needs, minimizing rework in the documentation, increasing the motivation of the personnel involved and promoting well-being within the work environment. Some theoretical methodological tools were implemented in the case of Engineering laboratories of the Faculty of Higher Studies Aragón, that support and complement the teaching-learning process in the theoretical-practical subjects of the curricula of the engineering bachelor??s degrees, providing students with practical training in the use of equipment, devices, and tools, as well as extracurricular courses. In the study participated the stakeholders of laboratories. From the results, it was observed that the time for the documentation of the quality management system was reduced using the theoretical tools proposed in this study. In conclusion, this study will thus be useful as a starting point in using formal tools for the implementation of ISO 9001: 2015 standard.
Modeling the Adoption of Sustainable Practices in the Supply Chain: A Game Theory Approach
Journal of Advanced Management Science
Aida Huerta Barrientos 1 , Idalia Flores De La Mota 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Keywords: supply chain, agent-based modeling, game theory approach, simulation, sustainability, 2030 agenda
Abstract: One goal of the 2030 Agenda for Sustainable Development of the United Nations is strengthening the means of implementing and revitalizing the Global Partnership for Sustainable Development. So, the adoption of sustainable practices into the management and operation of supply chains is a big challenge that companies need to face. However, the research in this area has mainly been qualitative and the developed models do not take into account the social pillar of sustainable development. The aim of this paper is to develop an agent-based model to analyze the factors that mainly influence the interactions among the functional companies of supply chains for the adoption of sustainable practices considering social aspects. First, we develop a conceptual model about the interactions among companies of supply chains based on the pair wise Prisioners Dilemma game and the game-dynamical replicator equations for multiple populations. Then, we implement the model using NetLogoTM software. We design some scenarios varying factors to analyze how the adoption of sustainable practices evolves in time. We prove that the interactions between companies that do not prefer to adopt sustainable practices with those who have already adopted the practices influence the decision to adopting such practices in a positive way. Our results provide a game theoretic model for sustainable supply chains.
Effectiveness of Physical Barriers Installation for Prevention of Incidents in Mexico City??s Subway System
Journal of Industrial Engineering
Gerardo de Jesús Portillo Villasana 1 , Aida Huerta Barrientos 1 , Yazmin Dillarza Andrade 1
1 Universidad Nacional Autónoma de México, Facultad de Ingeniería

Abstract: Nowadays, suicides inside the installations of subway platforms are considered a public health problem in Mexico City. One solution to prevent them is the installation of physical barriers, but their high cost is unattractive for governmental authorities. Traditional approaches of research on the effectiveness of physical barriers for preventing suicides have been limited to analyzing statistically the effects of installing platform screen doors and blue lights on subway platforms. Although considerable progress has been made in this field, many important issues remain unexplored. This study investigates the effectiveness of physical barriers installation for prevention of incidents in Mexico City subway system by means of an agent-based simulation model. Firstly, the design of physical barriers for prevention of incidents in Mexico City subway system is described. Secondly, a conceptual model of the Zócalo station subway platform is presented. Thirdly, an agent-based simulation model of Zócalo station subway platform is implemented using AnyLogic? software considering normal operations of the subway station. This study shows that physical barriers installation on the Zócalo subway platform can effectively prevent 76% of passenger??s suicides.