Prototipo de la fabricación de una bóveda con hormigón autocompactante con fibras poliméricas. Lecciones aprendidas

La realización de obras en las que se emplean materiales no tradicionales lleva asociada una complejidad estructural y constructiva. Con la comprobación in situ mediante la realización de un prototipo, se podrá poner a punto los equipos materiales y personales, los procedimientos de definición y ejecución, modelos de cálculos utilizados, etc. Con este objetivo se realizó un prototipo de una bóveda representativa a escala real que permitiera: seleccionar la dosificación de hormigón, entre las estudiadas previamente; optimizar el proceso de colocación, ajustando la localización de los puntos de hormigonado; y comprobar la adecuación de los equipos de hormigonado. Con las lecciones aprendidas de la fabricación de este prototipo se plantearon las modificaciones que se deben incorporar en obra. La experiencia adquirida llevó a modificar las fases de hormigonado y permitió adaptar los materiales al elemento construido

Accurate control of a liquid-crystal display to produce a homogenized Fourier transform for holographic memories

We show an accurate procedure to obtain a Fourier transform (FT) with no dc term using a commercial twisted-nematic liquid-crystal display. We focus on the application to holographic storage of binary data pages, where a drastic decrease of the dc term in the FT is highly desirable. Two different codification schemes are considered: binary π radians phase modulation and hybrid ternary modulation. Any deviation in the values of the amplitude and phase shift generates the appearance of a strong dc term. Experimental results confirm that the calculated configurations provide a FT with no dc term, thus showing the effectiveness of the proposal.This work was supported by the “Ministerio de Educación y Ciencia (Spain)” under projects FIS2005-05881-C02-01 and FIS2005-05881-C02-02, and by the “Generalitat Valenciana” under Project GV06/007

Array of Microfluidic Beam Resonators for Density and Viscosity Analysis of Liquids

This paper reports on the design, fabrication, and evaluation of a mass density and viscosity sensor based on an array of polysilicon microbeam resonators integrated with 20 pL fluidic microchannels. When filled with water, resonators exhibit resonant frequencies close to 500 KHz and Q-factor values of 400 operating at atmospheric pressure and ambient temperature. Real-time measurements are highly reproducible and only require 250 μL of the sample fluid. The built-in interferometric readout enables automatic detection of the beams increasing the throughput analysis and reducing detection times. The frequency shift response shows a linear behavior in accordance with the density of evaluated solvents, organic solutions, and alcoholic drinks, reporting a mass responsivity of 7.4 Hz/pg. Also, the sensor is capable of measuring the viscosity of liquid phase samples with a resolution of 0.15 cP by tracking the Q-factor response of the sensor within a linear regime between 1 to 2.6 cP. This approach demonstrates the ability to identify in real-time changes of fluids in the liquid phase that could provide a valuable assessment for bioanalytical applications

Braceros, Mexicans, Americans, and Schools: (Re) imagining Teaching and Learning in Mexican America

This article examines the stories of Braceros, Mexican contract workers who participated in an international labor agreement between the United States and México between 1942 and 1964. The stories Braceros tell challenge some conventional historiographical notions that they were powerless agents and victims of exploitative labor practices. The stories shed new light regarding the kinds of agency and power Braceros actually displayed in negotiating certain circumstances specific to their work

Influence of Thickness on the Holographic Parameters of H-PDLC Materials

For photopolymers the compound concentrations and final thickness of the sample should be known in order to model hologram formation and introduce the reaction-diffusion kinetics of the monomer-polymer system. In principle the cell thickness can be controlled by bead spacers between the two pieces of ITO glass. In this paper we report a study of the influence of thickness on the holographic properties of this type of materials. To fit the physical and optical thickness of the samples we used the rigorous coupled wave analysis assuming an exponential decay in the refractive index modulation.The work was supported by the “Ministerio de Economía y Competitividad” of Spain under Projects FIS2011-29803-C02-01 and FIS2011-29803-C02-02 and by the “Generalitat Valenciana” of Spain under Projects PROMETEO/2011/021 and ISIC/2012/013

Habilidades comunicativas de personas con discapacidad auditiva para la propuesta de espacios especializados en comunicación alternativa Trujillo - Perú 2021

La presente tesis tiene por objetivo determinar las habilidades comunicativas de personas con discapacidad auditiva, que aportarán en la propuesta de espacios especializados en comunicación alternativa. El estudio se centra en la aplicación de una metodología cualitativa, de tipo básico y diseño investigación-acción. El proceso metodológico se realiza mediante el uso de entrevista, basada en una guía de preguntas que son aplicadas en diversos contextos, en los que se desenvuelven los sujetos propios de la investigación. Se definieron las habilidades comunicativas de personas con discapacidad auditiva, condiciones especiales de los espacios y finalmente se propuso criterios de diseño de espacios especializados en comunicación alternativa, concluyendo que las habilidades comunicativas de personas con discapacidad auditiva son 7, siendo más importante el lenguaje de señas. Teniendo en cuenta las condiciones y criterios para los espacios especializados para personas con discapacidad auditiva, se incentivará su desarrollo y su productividad, motivándolos a lograr su autonomía, de este modo haciéndose cumplir el derecho de la igualdad, y demostrando la importancia de una arquitectura sin barreras, que no solo brindará la fácil accesibilidad de aquellas personas con discapacidad auditiva, sino también permite el desarrollo de nuestra ciudad y el desarrollo como sociedad

Fermentation of Cocoa Beans

Cocoa bean fermentation is a spontaneous process driven by an ordered microbial succession of a wide range of yeasts, lactic acid and acetic acid bacteria, some aerobic sporeforming bacteria and various species of filamentous fungi. The process of cocoa fermentation is a very important step for developing chocolate flavor precursors which are attributable to the metabolism of succession microbial. The microbial ecology of cocoa has been studied in much of the world. In Venezuela, studies have been carried out with Criollo, Forastero, and Trinitario cocoa, fermented under various conditions, the results obtained coinciding with the reported scientific information. Fermentation must be associated with the type of cocoa available, carried out knowing the final processing and derivative (paste, butter, powder). The results shown in this chapter correspond to investigations carried out with cocoa from three locations in Venezuela. The quantification, identification, isolation, functionality of the most representative microbiota involved in the fermentation of these grains was sought. This to give possible answers to the fermentation times and improvement of the commercial quality. Likewise, generate greater interest on the part of the producers in carrying out the fermentation

Exploring binary and ternary modulations on a PA-LCoS device for holographic data storage in a PVA/AA photopolymer

We focus on the novelty of three elements in holographic data storage systems (HDSS): the data pager, where we introduce a parallel-aligned liquid crystal on silicon (PA-LCoS) microdisplay; the recording material, where we consider the highly versatile PVA/AA photopolymer; and also in the architecture of the object arm, where a convergent correlator system is introduced. We show that PA-LCoS devices cannot implement pure hybrid-ternary modulated (HTM) data pages but a rather close approximation. Validation of the HDSS expressions for the convergent correlator and comparison with the widespread 4-f system is performed. Experimental results with PVA/AA material showing bit-error rates (BER) in the range of 10−3, further show its potential application for HDSS, and also demonstrate the validity of the testing platform and PA-LCoS calibration and optimization.Work supported by Ministerio de Trabajo y Competitividad of Spain (projects FIS2011- 29803-C02-01 and FIS2011-29803-C02-02), by Generalitat Valenciana of Spain (projects PROMETEOII/2015/015 and ISIC/2012/013), and by Univ. de Alicante (project GRE12-14

3D FDTD analysis of cross-talk in pixelated PA-LCos devices: impact of fill factor and size pixel on S2 and S3 parameters

In the last decades, new technology fabrication developments have permitted increased resolution and reduced pixel size of Liquid crystal on silicon (LCoS) microdisplays. However, the pixel size reduction triggers the microdisplay performance degradation due to different phenomena, such as the cross-talk between neighbouring pixels, fringing fields, out-of-plane reorientation of the liquid crystal director, and diffraction effects due to the pixelated grid pattern of the microdisplay. In this work, a full 3D simulation model has been applied to predict the liquid crystal director orientation as a function of space and external voltage. The scheme here considered provides the complete vectorial information of the electromagnetic field distribution produced by one single pixel illuminated by plane waves circularly polarised. This analysis is carried on for several pixel and gap sizes for different external voltages. This research focuses on S2 and S3 Stokes parameters and how their behaviour is affected due to the cross-talk phenomena previously presented.The work was supported by the “Generalitat Valenciana” (IDIFEDER/2021/014 cofunded by FEDER EU pro- gram, and project PROMETEO/2021/006, GRISOLIAP/2021/106), and by “Ministerio de Ciencia e Innovación” of Spain (projects PID2021-123124OB-I00; PID2019-106601RB-I00)