Numerical methods for computing Casimir interactions

We review several different approaches for computing Casimir forces and related fluctuation-induced interactions between bodies of arbitrary shapes and materials. The relationships between this problem and well known computational techniques from classical electromagnetism are emphasized. We also review the basic principles of standard computational methods, categorizing them according to three criteria---choice of problem, basis, and solution technique---that can be used to classify proposals for the Casimir problem as well. In this way, mature classical methods can be exploited to model Casimir physics, with a few important modifications.Comment: 46 pages, 142 references, 5 figures. To appear in upcoming Lecture Notes in Physics book on Casimir Physic

Modulation of near-field heat transfer between two gratings

We present a theoretical study of near-field heat transfer between two uniaxial anisotropic planar structures. We investigate how the distance and relative orientation (with respect to their optical axes) between the objects affect the heat flux. In particular, we show that by changing the angle between the optical axes it is possible in certain cases to modulate the net heat flux up to 90% at room temperature, and discuss possible applications of such a strong effect

A TEORIA DA CONFORMIDADE SOCIAL E A INFLUÊNCIA DO PERFIL DE AUTORIDADE NA PERSUASÃO DO VOTO ELEITORAL

Studies and experiments in social psychology, according to the view of Acsh (1951) suggest that individuals tend to mimic the pattern of behavior in a given nucleus that has a majority reflecting on the same object. Even if they reason against the contrary, these people tend to change their opinion on the grounds of the group. This Milgram group (2009) also reflects on the authority profile present in them, in which it induces those surveyed to follow a profile of influence in the formation of their choices and answers. Nevertheless, according to a psychological political analysis, it points to an influence of groups that have in it actors who exercise a certain authority, such as religious leaders, in the figure of the church, who can persuade their followers by explaining this theory. This social conformism also reflects the desire not to show up or vulnerable the majority. Following this line of social psychology, this article will explore electoral elections through the influence of religious and local leaders in the persuasion of the electoral vote.Estudos e experimentos da psicologia social, segundo a visão de Acsh (1951) sugerem que os indivíduos tendem a imitar o padrão de comportamento em um dado núcleo que tenha uma maioria refletindo sobre o mesmo objeto. Mesmo raciocinando contrariamente, essas pessoas tendem a mudar a sua opinião em razão do grupo. A esse grupo Milgram (2009) também reflete sobre o perfil de autoridade neles presentes, na qual induz os pesquisados a seguir um perfil de influência na formação das suas escolhas e respostas. Não obstante, segundo uma análise política psicológica, aponta para uma influência de grupos que nele tenha atores que exercem uma certa autoridade, tal como os líderes religiosos, na figura da igreja, que podem persuadir os seus seguidores através da explicação desta teoria. Esse conformismo social também reflete a vontade de não se evidenciar em exposição ou vulnerável a maioria. Seguindo essa linha da psicologia social, este artigo irá explorar os pleitos eleitorais através da influência de líderes religiosos e locais na persuasão do voto eleitoral

Citizen science set in motion: DIY light traps for phlebotomine sand flies

Phlebotomine sand flies are vectors of various diseases such as leishmaniasis making them a public health concern worldwide. To increase the tools available for the study of sand flies, we developed do it yourself (DIY) light traps made mainly from recycled materials and tested their effectiveness in the field. This new model is named Flebocollect light trap. In this report we describe how the DIY light traps are prepared and illustrate the process with a short video. Lowering costs makes this resource available for citizen science and educational projects, and for research groups with a low budget such as those in developing countries. Our preliminary results showed a capture rate increase of 37 % of DIY light traps over commercial CDC, although no statistical evidence has been obtainedThis study was conducted within the framework of the BRITEC (Bringing Research Into ThE Classroom) Research Project funded by the European Union in the Erasmus + KA2 Program (2018-1-PL01-KA201- 051080

Energy Management Strategies in hydrogen Smart-Grids: A laboratory experience

As microgrids gain reputation, nations are making decisions towards a new energetic paradigm where the centralized model is being abandoned in favor of a more sophisticated, reliable, environmentally friendly and decentralized one. The implementation of such sophisticated systems drive to find out new control techniques that make the system “smart”, bringing the Smart-Grid concept. This paper studies the role of Energy Management Strategies (EMSs) in hydrogen microgrids, covering both theoretical and experimental sides. It first describes the commissioning of a new labscale microgrid system to analyze a set of different EMS performance in real-life. This is followed by a summary of the approach used towards obtaining dynamic models to study and refine the different controllers implemented within this work. Then the implementation and validation of the developed EMSs using the new labscale microgrid are discussed. Experimental results are shown comparing the response of simple strategies (hysteresis band) against complex on-line optimization techniques, such as the Model Predictive Control. The difference between both approaches is extensively discussed. Results evidence how different control techniques can greatly influence the plant performance and finally we provide a set of guidelines for designing and operating Smart Grids.Ministerio de Economía y Competitividad DPI2013-46912-C2-1-

Experimental validation of an optical and thermal model of a Linear Fresnel Collector

2nd European Conference on Polygeneration – 30th March 1st April, 2011– Tarragona, SpainThis paper describes the design and validation of a mathematical model for a solar Fresnel collector. The function of the model is to simulate the optical and thermal dynamics of a Fresnel system for heating water. The model is validated using real data gathered from a cooling plant with double effect absorption chiller located in the School of Engineering University of Seville, Spain (Experimental cooling plant is also described in the paper). Comparison of calculated and plant measured data shows that the error is lower than 3% in the optical model and within 7% in the thermal model. The model uses a new approach to include a solar tracking mirror mechanism in one axis. This tracking has been designed to maximise the reception of available solar radiation by the absorption pipe. The thermal model used is based around classical models for solar receivers and it is validated with real operating data gathered from a supervisor system. The Fresnel model has been designed with sufficient flexibility to consider different geometries and thermal parameters, and may be used to simulate the performance of a proposed Fresnel collector system at any location

Biomimetic flow fields for proton exchange membrane fuel cells: A review of design trends

Bipolar Plate design is one of the most active research fields in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) development. Bipolar Plates are key components for ensuring an appropriate water management within the cell, preventing flooding and enhancing the cell operation at high current densities. This work presents a literature review covering bipolar plate designs based on nature or biological structures such as fractals, leaves or lungs. Biological inspiration comes from the fact that fluid distribution systems found in plants and animals such as leaves, blood vessels, or lungs perform their functions (mostly the same functions that are required for bipolar plates) with a remarkable efficiency, after millions of years of natural evolution. Such biomimetic designs have been explored to date with success, but it is generally acknowledged that biomimetic designs have not yet achieved their full potential. Many biomimetic designs have been derived using computer simulation tools, in particular Computational Fluid Dynamics (CFD) so that the use of CFD is included in the review. A detailed review including performance benchmarking, time line evolution, challenges and proposals, as well as manufacturing issues is discussed.Ministerio de Ciencia, Innovación y Universidades ENE2017-91159-EXPMinisterio de Economía y Competitividad UNSE15-CE296

Músicos latino-americanos no exílio : Música, deslocamentos e participaçao política

Este trabalho faz parte de um projeto de investigação financiado, em sua primeira parte, pelo CNPq, desenvolvido por pesquisadores de várias universidades. Tem por objetivo abordar a história dos músicos exilados durante as ditaduras ocorridas no Brasil, Argentina, Paraguai, Uruguai e Chile, entre as décadas de 1960 e 1980, mediante a análise da filmografia, bibliografia, discografia, documentos oficiais das polícias políticas e serviços de informação, e, principalmente, a partir dos testemunhos dos envolvidos. Sabemos que muitos músicos de renome foram exilados e suas trajetórias foram estudadas ou difundidas pelos meios de comunicação. Contudo, músicos menos conhecidos ou de menor projeção midiática, igualmente foram perseguidos pelas ditaduras de seus países, mas não são suficientemente contemplados pelas pesquisas acadêmicas e pela Imprensa. Alguns foram militantes de organizações de esquerda, outros se exilaram por outros motivos. Partimos da perspectiva de que se torna necessário atentar para a heterogeneidade desses percursos de exílio, a fim de entender os múltiplos caminhos que sua militância percorrem.Instituto de Investigaciones en Humanidades y Ciencias Sociales (IdIHCS

Analytical approach to ground heat losses for high temperature thermal storage systems

A new approach to estimate the heat loss from thermal energy storage tank foundations is presented. Results are presented through analytical correlations based on numerical solutions for the steady-state heat conduction problem for thermal energy slab-on-grade tanks with uniform insulation. Model results were verified with other well-established benchmark problems with similar boundary conditions and validated with experimental data with excellent agreement. In addition to the TES foundation heat loss, new correlations for the maximum temperature and for the radial evolution of the temperature underneath the insulation layer are also provided, giving important information related to the tank foundation design. The correlated variables are of primordial importance in the tank foundation design because, due to the typical high operating storage temperatures, an inappropriate tank foundation insulation would lead not only to a not desired loss of energy but also to an inadmissible increase of the temperatures underneath the insulation layer, affecting the structural stability of the tank. The proposed correlations provide a quick method for the estimation of total tank foundation heat losses and soil maximum temperature reached underneath the insulation layer, saving time, and cost on the engineering tank foundation design process. Finally, a comprehensive parametric analysis of the variables of interest is made and a set of cases covering a wide range of tank sizes, insulation levels, depths to water table, and storage temperatures are solved