3,256 research outputs found
Qualified voting mechanisms
We study voting mechanisms, which consist of two elements: a profile of sets of votes (this profile describes the votes that voters are allowed to cast) and a voting scheme (which explains how to aggregate those votes). To investigate how these two elements interact, we impose some properties on the sets of votes (i.e., regularity ) and on the voting scheme (i.e., candidate monotonicity, candidate anonymity, and weak neutrality ). We characterize the family of voting schemes that satisfy some of those properties and analyze the role played by the structure of the sets of votes in these characterizations. Voting, approval voting rule, plurality rule, monotonicity, anonymity, neutrality, qualified votin
Performance evaluation of low concentrating photovoltaic/thermal systems: A case study from Sweden
Some of the main bottlenecks for the development and commercialization of photovoltaic/thermal hybrids are the lack of an internationally recognized standard testing procedure as well as a method to compare different hybrids with each other and with conventional alternatives. A complete methodology to characterize, simulate and evaluate concentrating photovoltaic/thermal hybrids has been proposed and exemplified in a particular case study. By using the suggested testing method, the hybrid parameters were experimentally determined. These were used in a validated simulation model that estimates the hybrid outputs in different geographic locations. Furthermore, the method includes a comparison of the hybrid performance with conventional collectors and photovoltaic modules working side-by-side. The measurements show that the hybrid electrical efficiency is 6.4% while the optical efficiency is 0.45 and the U-value 1.9 W/m(2) degrees C. These values are poor when compared with the parameters of standard PV modules and flat plate collectors. Also, the beam irradiation incident on a north south axis tracking surface is 20-40% lower than the global irradiation incident on a fixed surface at optimal tilt. There is margin of improvement for the studied hybrid but this combination makes it difficult for concentrating hybrids to compete with conventional PV modules and flat plate collectors. (C) 2011 Elsevier Ltd. All rights reserved
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Determining barotrauma in the Pictus catfish, Pimelodus pictus, experimentally exposed to simulated hydropower turbine passage
Hydropower development poses severe threats to the aquatic diversity and ecosystem services. One such threat is the exposure of fish to extreme conditions within hydropower facilities. Fish may suffer rapid decompression when passing through turbines or entering/inhabiting the draft tubes, which can lead to barotrauma and mortality. We aimed to evaluate the effects of rapid decompression on the Amazonian benthic species Pimelodus pictus (Pictus catfish), by simulating in hypo/hyperbaric chambers. The most frequent injuries in Pictus catfish exposed to simulated rapid decompression were swim bladder rupture, intestine rupture, internal haemorrhage and embolism. The occurrence and magnitude of internal haemorrhaging and emboli were related to the ratio of pressure change and the decompression timespan, while swim bladder rupture occurred even at relatively low ratios. Emboli was present almost entirely among fish with a ruptured swim bladder. Importantly, all fish were negatively buoyant prior to exposure to decompression, posing challenges to data analysis. Therefore, barotrauma studies with benthic fish species are deemed to be challenging and are likely to require the use of complementary approaches. Research is needed to understand the state of buoyancy of benthic fish in the wild and develop methods to accurately replicate these in a controlled testing environment
A implementação do sistema de custos proposto pelo governo federal: uma análise sob a ótica institucional
As informações sobre custos no setor público são importantes para uma análise adequada de eficiência e qualidade do gasto. Em países de referência a implementação dessa metodologia teve caráter mais abrangente, não focado apenas em questões técnicas. A teoria institucional discute justamente a necessidade de que tais transformações no cotidiano dos servidores devem envolver ajustes das normas, valores e práticas em uso nas organizações envolvidas. Neste contexto é que se insere este trabalho, que procurou através da ótica institucional, e comparando com o processo de reforma australiano, analisar como se desenvolveu no governo federal brasileiro a incorporação de novas ferramentas de gestão. Assim, identificou-se, diferentemente do que sugere a teoria institucional e a experiência internacional, que o governo brasileiro optou pela implantação de uma solução tecnológica, em detrimento de uma mobilização institucional mais ampla
Qualidade de vida dos motoristas e cobradores de empresas de transporte coletivo: um enfoque ergonômico /
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Este estudo pretendeu oferecer uma visão amplificada da qualidade de vida de motoristas e cobradores de três das maiores empresas de transporte coletivo do município do Rio de Janeiro. em um enfoque ergonômico, no qual a Ergonomia foi entendida numa perspectiva holística. De um lado, a categoria vem sofrendo pressões populares que evidenciam a má qualidade do serviço prestado. De outro, os sindicatos apresentam publicações e dão declarações e entrevistas nas quais a qualidade do atendimento aos profissionais é ressaltada. Para evidenciar as divergências, o pesquisador se valeu de publicações dos sindicatos nas quais há uma preocupação com a qualidade do transporte, dos usuários. Psicólogos, pedagogos e administradores declaram-se empenhados na melhoria dos serviços que prestam. Os motoristas e cobradores foram acompanhados em viagens rápidas e longas por duas pesquisadoras durante três meses consecutivos. Foi aplicado, concomitantemente à observação participante, um questionário no qual os profissionais puderam externar satisfações e frustrações acerca do trabalho, do turno, das empresas, dos ônibus, da qualidade de vida. Os resultados revelaram uma discrepância entre o que os profissionais realmente fazem no seu dia a dia e o que declararam. A essa discrepância soma-se o que psicólogos, administradores e donos de empresa declaram. Finalmente, os motoristas e cobradores analisados não possuem uma boa qualidade de vida, necessitando de atenção maior por parte das empresas no sentido de adotar não apenas os princípios ergonômicos, mas também promover programas efetivos de qualidade. Conclui-se pela sugestão de hipóteses que, se comprovadas, permitirão uma melhor avaliação do caso em apreço
Deciding whether a law is constitutional, interpretable, or unconstitutional
A high court has to decide whether a lawis constitutional, unconstitutional, or interpretable. The voting system is runoff. Runoff voting systems can be interpreted both, as social choice functions or as mechanisms. It is known that, for universal domains of preferences, runoff voting systems have several drawbacks as social choice functions. Although in our setting the preferences are restricted to be singlepeaked over three alternatives, these problems persist. Runoff mechanisms are not well-behaved either: they do not implement any Condorcet consistent social choice function in undominated subgame perfect Nash equilibria. We show, however, that some Condorcet consistent social choice functions can be implemented in dominant strategies via other simple and natural mechanisms
Methodology and parameters to analyse daylighting and energy use in dense cities: A literature review
Low energy buildings are key to reduce global energy use. However, achieving low energy use and good daylight levels simultaneously in dense cities is challenging. This article reviews relevant studies dealing with energy use and daylighting in dense residential urban blocks located in Nordic climates. The literature review combines a systematic and a ‘snowball’ search approach. Findings indicate that previous research relies heavily on parametric design as a tool. Few density metrics were found particularly relevant to describe the interplay between density, daylight, and energy use.However, the limited body of research achieved so far in the Nordic climate makes it difficult to draw a clear conclusion, suggesting that additional research is required
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