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Thermodynamic, structural and dynamic properties of ionic liquids [C4mim][CF3COO]

, [C4mim][Br]

in the condensed phase, using molecular simulations

Joel Sánchez-Badillo JORGE LOPEZ LEMUS Marco Gallo Ricardo Guirado (2019)

Articulo de investigacion

In this work a series of thermodynamic, structural, and dynamical properties for the 1-butyl-3-methylimidazolium trifluoroacetate ([C4mim][CF3COO]) and 1-butyl-3-methylimidazolium bromide, ([C4mim][Br]) ionic liquids (ILs) were calculated using Non-polarizable Force Fields (FF), parameterized using a methodology developed previously within the research group, for condensed phase applications. Properties such as the Vapor-Liquid Equilibrium (VLE) curve, critical points (ρc, Tc), Radial, Spatial and Combined Distribution Functions and self-diffusion coefficients were calculated using Equilibrium Molecular Dynamics simulations (EMD); other properties such as shear viscosities and thermal conductivities were calculated using Non-Equilibrium Molecular Dynamics simulations (NEMD). The results obtained in this work indicated that the calculated critical points are comparable with those available in the literature. The calculated structural information for these two ILs indicated that the anions interact mainly with hydrogen atoms from both the imidazolium ring and the methyl chain; the bromide anion displays twice the hydrogen coordination number than the oxygen atoms from the trifluoroacetate anion. Furthermore, Non-Covalent interactions (NCI index), determined by DFT calculations, revealed that some hydrogen bonds in the [C4mim][Br] IL displayed similar strength to those in the [C4mim][CF3COO] IL, in spite of the shorter O−–H distances found in the latter IL. The majority of the calculated transport properties presented reasonable agreement with the experimental available data. Nonetheless, the self-diffusion coefficients determined in this work are under-estimated with respect to experimental values; however, by escalating the electrostatic atomic charges for the anion and cation to ±0.8e, only for this property, a remarkable improvement was obtained. Experimental evidence was recovered for most of the calculated properties and to the best of our knowledge, some new predictions were done mainly in thermodynamic states where data are not available. To validate the FF, developed previously within the research group, dynamic properties were also evaluated for a series of ILs such as [C4mim][PF6], [C4mim][BF4], [C4mim][OMs], and [C4mim][NTf2] ILs.

Article

ionic liquid molecular dynamics force field CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA

Identificación de terminales de motores trifásicos de 6, 9 y 12 puntas, diagrama de flujo modo automático

JOSE LUIS VIRAMONTES REYNA (2021)

Los empalmes ultrasónicos cable a cable en un arnés automotriz permiten enviar la misma señal eléctrica a diferentes módulos, localizados en distintas ubicaciones dentro del vehículo. La prueba de resistencia a la tracción es de las principales para evaluar el desempeño del empalme. El estudio se enfoca en determinar una relación analítica para estimar la fuerza de tracción que resistirá el empalme en base al área transversal de los cables que lo integran, para permitir a los arquitectos eléctricos comparar la fuerza de tracción estimada que resistirá el empalme, con la fuerza mínima requerida por la normatividad vigente, proporcionando una herramienta adicional para prevenir fallas en los vehículos provocadas por empalmes fracturados desde etapas tempranas del diseño del arnés. En conjunto con la relación analítica obtenida, también se obtiene una relación por regresión basada en los datos experimentales de las pruebas. Por último, se estima la fuerza de tensión de 21 empalmes con las dos relaciones logrando un error menor o igual al 10% con relación de la fuerza obtenida experimentalmente.

Wire to wire ultrasonic splices in an automotive harness enable to send the same electrical signal to different modules, located in different positions within the vehicle. The tensile strength test is one of the main trials to evaluate the splice performance. The study focuses in establish an analytic relationship to estimate the traction force supported by the splice based in the cross sectional area of the wires that comprise it, allowing electrical architects compare the estimated tensile force that the splice will resist, with the minimum force required by current standard, providing an additional tool to prevent vehicle failures caused by fractured splices since early stages of harness design. Altogether with the obtained analytic relationship, also a regression relation is obtained based in the experimental data of the tests. Finally, the tensile force of 21 splices is estimated with both relationships achieving an error less or equal to 10% of the test tension force.

Master thesis

Empalme ultrasónico Fuerza Tracción Materials resistance Ultrasonic splice Force Traction INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES RESISTENCIA DE MATERIALES RESISTENCIA DE MATERIALES

The quantum Rabi model for two qubits

BLAS MANUEL RODRIGUEZ LARA (2013)

We study a system composed of two nonidentical qubits coupled to a single mode quantum field. We calculate the spectra of the system in the deepstrong-coupling regime via perturbation theory up to second order corrections, and show that it converges to two forced oscillator chains for cases well into that regime. Our predictions are confirmed by numerical calculation of the spectra using a parity decomposition of the corresponding Hilbert space. The numerical results point to two interesting behaviors in the ultra-strong-coupling regime: the rotating wave approximation is valid for some particular cases and there exist crossings in the spectra within each parity subspace. We also present the normal modes of the system and give an example of the time evolution of the mean photon number, population inversion, von Neuman entropy and Wootters concurrence in the ultra-strong- and deep-strongcoupling regimes.

Article

Qubits Quantum field Hilbert space CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Efecto del tamaño de la bellota y del cambio climático sobre la germinación de encinos (Qercus SPP.)

Erik José Sánchez Montes de Oca (2019)

"La producción de semillas en ecosistemas forestales está regulada por factores ambientales y genéticos, donde los árboles parentales influyen en los rasgos de las semillas. Así, el tamaño de las semillas puede influir en la germinación y supervivencia de las plántulas a nivel interespecífico e intraespecífico. Por otra parte, los modelos climáticos predicen aumentos de temperatura y disminuciones en la precipitación para la mayor parte de México, por lo que se puede esperar que especies arbóreas con semillas recalcitrantes sean susceptibles a estos cambios y se reduzca su reclutamiento. Los encinos (género Quercus; familia Fagaceae) producen frutos secos, uniseminados, tipo nuez denominados “bellotas”, que son altamente recalcitrantes y presentan gran variabilidad en su tamaño. México es el centro de diversificación más importante de este grupo (tres secciones del subgénero Quercus: Lobatae, Quercus y Protobalanus). Lo anterior proporciona una oportunidad excepcional para evaluar los efectos de los árboles parentales sobre el tamaño de las bellotas y el efecto de este rasgo sobre la germinación y supervivencia de plántulas, tanto a nivel interespecífico como intraespecífico. Además, teniendo en cuenta la alta variabilidad en este rasgo, se puede evaluar su relevancia en escenarios de cambio climático. Para alcanzar estos objetivos, se desarrollaron experimentos en condiciones controladas y en campo. En el primer capítulo de la tesis, se evalúa el efecto a partir de los atributos de árboles parentales sobre el tamaño de las bellotas, su germinación y la supervivencia de plántulas. Esto se realizó midiendo atributos de los árboles parentales y evaluando si estaban asociados a la producción de bellotas y su tamaño. Los resultados indicaron que la cantidad de bellotas producidas y su tamaño están determinadas por los atributos foliares de las ramillas terminales donde se desarrollan los frutos. Además, conforme aumenta el peso de las bellotas, se incrementa su probabilidad de germinación. El segundo capítulo de la tesis aborda los efectos de las diferencias en el tamaño de las bellotas sobre la germinación a nivel interespecífico e intraespecifíco. Para esto se seleccionaron bellotas de encinos rojos (sección Lobatae) y encinos blancos (sección Quercus) de la Sierra de Álvarez (San Luis Potosí) con los que se desarrolló un experimento de jardín común donde se sembraron bellotas viables de estas especies."

"Seed production in forest ecosystems is regulated by environmental and genetic factors, where parental trees influence on seed traits. In this way, seed size can influence germination and survival of seedlings, both at interspecific and intraspecific levels. On the other hand, climate models predict that temperature will increase and rainfall will reduce across Mexico and, thus, tree species with recalcitrant seeds are likely to be highly susceptible to these changes and their recruitment is expected to be reduced. The oaks (genus Quercus; family Fagaceae) produce single-seed nuts, namely “acorns” that are highly recalcitrant and exhibit great variability in their sizes. Mexico is the most important diversification center of this group (three sections of the Quercus subgenus: Lobatae, Quercus and Protobalanus). This provides an exceptional opportunity to evaluate the effects of parental trees on acorn size of acorns and the manner in which this trait affects germination and survival of seedlings at interspecific and intraspecific levels. Additionally, taking into account this elevated variability in acorn size, the relevance of this trait under climate change scenarios can be also assessed. To achieve these objectives, we conducted experiments under controlled laboratory conditions and in the field. The first chapter of this thesis focuses on the effects of parental trees on acorn size, their germination and seedling survival. For this, we measured attributes of parental trees and assessed whether they were associated with acorn production and their size. Our results indicated that acorn production and their size are determined by the foliar attributes of the terminal branches in which these fruits are developed. Additionally, as the weight of the acorns increases, their germination probability raises. The second chapter of the thesis addresses the effects of differences in acorn size on germination at interspecific and intraspecific levels. For this, we collected acorns of red oaks (Lobatae section) and white oaks (Quercus section) in Sierra de Álvarez (San Luis Potosí) and performed a common garden experiment. The results of this experiment indicated that white oaks produce larger acorns than red oaks, while this positively influences their germination rates. At the intraspecific level, germination of acorns in red oaks strongly depends on seminal biomass, while these effects are less noticeable in white oaks."

Doctoral thesis

Encinos Biomasa seminal Efectos maternos Tamaño de semilla Germinación Cambio climático Bosques Campos abandonados Plántulas Oaks Seminal biomass Maternal effects Seed size Germination Climate change Forests Abandoned fields Seedling CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS CIENCIA FORESTAL CONSERVACIÓN CONSERVACIÓN

Photon transport in binary photonic lattices

BLAS MANUEL RODRIGUEZ LARA Héctor Manuel Moya Cessa (2013)

We present a review on the mathematical methods used to theoretically study classical propagation and quantum transport in arrays of coupled photonic waveguides. We focus on analysing two types of binary photonic lattices where selfenergies or couplings are alternated. For didactic reasons, we split the analysis in classical propagation and quantum transport but all methods can be implemented, mutatis mutandis, in any given case. On the classical side, we use coupled mode theory and present an operator approach to Floquet-Bloch theory in order to study the propagation of a classical electromagnetic field in two particular infinite binary lattices. On the quantum side, we study the transport of photons in equivalent finite and infinite binary lattices by couple mode theory and linear algebra methods involving orthogonal polynomials. Curiously the dynamics of finite size binary lattices can be expressed as roots and functions of Fibonacci polynomials.

Article

Mathematical methods Electromagnetic field Binary lattices Photon transport CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA

Eduardo Mendoza Torres (2013)

Our analysis of a VLBA 12-hour synthesis observation of the OH masers in awell-known star-forming region W49N has yielded valuable data that enables usto probe distributions of magnetic fields in both the maser columns and the inter-vening interstellar medium (ISM). The data consisting of detailed high angular-resolution images (with beam-width ∼20 milli-arc-seconds) of several dozen OH maser sources or spots, at 1612, 1665 and 1667 MHz, reveal anisotropic scatter broadening, with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. Such anisotropies have been reported earlier by Desai, Gwinn & Diamond (1994) and interpreted as induced by the local magnetic field parallel tothe Galactic plane. However, we find a) the apparent angular sizes on the averagea factor of about 2.5 less than those reported by Desai et al. (1994), indicating significantly less scattering than inferred earlier, and b) a significant deviation inthe average orientation of the scatter-broadened images (by ∼10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for afew Zeeman pairs in our set, significant differences (up to 6σ) are apparent in thescatter broadened images for the two hands of circular polarization, even when apparent velocity separation is less than 0.1 km s⁻¹. This may possibly be the first example of a Faraday rotation contribution to the diffractive effects in the ISM. Using the Zeeman pairs, we also study the distribution of magnetic field inthe W49N complex, finding no significant trend in the spatial structure function.In this paper, we present the details of our observations and analysis leading tothese findings, discuss implications of our results for the intervening anisotropic magneto-ionic medium, and suggest the possible implications for the structure of magnetic fields within this star-forming region.

Article

Masers ISM: molecules Magnetic fields Individual (W49N) Radio lines: ISM Structure function CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

On almost simple transcendental field extensions

ANTONIO GONZALEZ FERNANDEZ RODRIGO JIMENEZ CORREA JESUS EFREN PEREZ TERRAZAS (2015)

We study some properties of almost simple transcendental field extensions in order to analyze the endomorphisms ring of algebraically bounded Λ−modules where Λ is a semigenerically tame finite-dimensional k−algebra, k a perfect field.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA INGENIERÍA Y TECNOLOGÍA Algebraically bounded modules Field extension Perfect field Semigenerically tame algebra Transcendental extension

Asymmetric GaAs n-type double δ-doped quantum wells as a source of intersubband-related nonlinear optical response: Effects of an applied electric field

JUAN CARLOS MARTINEZ OROZCO ISAAC RODRIGUEZ VARGAS (2014)

In this work, the conduction band electron states and the associated intersubband-related linear and nonlinear optical absorption coefficient and relative refractive index change are calculated for an asymmetric double n-type δ-doped quantum well in a GaAs-matrix. The effects of an external applied static electric field are included. Values of the two-dimensional impurities density (N2d) of each single δ-doped quantum well are taken to vary within the range of 1.0×1012 to 7.0×1012 cm−2, consistent with the experimental data growth regime. The optical responses are reported as a function of the δ-doped impurities density and the applied electric field. It is shown that single electron states and the related optical quantities are significantly affected by the structural asymmetry of the double δ-doped quantum well system. In addition, a brief comparison with the free-carrier-related optical response is presented.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA δ-doped quantum wells Electric field Nonlinear optical properties

Diseño e implementación de una tarjeta con FPGA RAM Y ROM externas

GEOVANNI ZEPEDA ARCE (2018)

"El empleo de FPGAs (Field Programmable Gate Array) tiene ciertas ventajas, entre ellas la flexibilidad que se obtiene al desarrollar un prototipo. Un microprocesador o microcontrolador comercial tiene ciertas funciones que no pueden ser modificadas. En cambio, un FPGA puede ser reprogramado en poco tiempo con las funciones específicas que requiere un proyecto. En este trabajo se presenta el diseño e implementación de un microprocesador RISC (Reduced Instrucction Set Computer) de 32 bits destinado al control y automatización de sistemas. Las características principales del microprocesador son: una arquitectura Harvard y un conjunto de 16 instrucciones las cuales incluyen operaciones aritméticas con punto flotante (suma, resta, multiplicación y división), transferencia de datos, saltos condicionales y salto incondicional. Para la implementación de las instrucciones se diseñan los módulos: decodificador de instrucciones y Unidad Aritmética de Punto Flotante (ULA). El diseño de cada elemento se desarrolla en el lenguaje de descripción de hardware de Altera (AHDL). Para la instrumentación del sistema se diseña una tarjeta electrónica que tiene como base un FPGA Cyclone IV, una memoria RAM, una ROM y un módulo de interfaz inalámbrica Wi-Fi. La interfaz se utiliza para la carga, ejecución de algoritmos y la visualización de resultados desde un equipo de cómputo. Para demostrar la funcionalidad y practicidad de uso del sistema desarrollado, se presentan tres aplicaciones del sistema, este se aplicó en control de una mano robótica, en el control de un robot que emula los movimientos del cuello humano y en el control de un robot cartesiano de 3 grados de libertad. El procesador desarrollado permite resolver diversidad de problemas en forma secuencial suministrando versatilidad en la integración de sistemas digitales complejos, economizando recursos de hardware, esfuerzos de ingeniería y tiempo de desarrollo. "

Benemérita Universidad Autónoma de Puebla

Master thesis

Sistemas embebidos--Programación Microcontroladores Field Programmable Gate Arrays INGENIERÍA Y TECNOLOGÍA

Genus fields of cyclic l-extensions of rational function fields

VICTOR MANUEL BAUTISTA ANCONA MARTHA RZEDOWSKI CALDERON GABRIEL DANIEL VILLA SALVADOR (2013)

We give a construction of genus fields for Kummer cyclic l–extensions of rational congruence function fields, l a prime number. First we find this genus field for a field contained in a cyclotomic function field using Leopoldt’s construction by means of Dirichlet characters and the Hilbert class field defined by Rosen. The general case follows from this. This generalizes the result obtained by Peng for a cyclic extension of degree l.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA INGENIERÍA Y TECNOLOGÍA Genus fields Congruence function fields Global fields Dirichlet characters Cyclotomic function fields Cyclic extensions Kummer extensions