971 resultados para Electronic equipment


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Paper submitted to the 7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013), New Delhi, India, 23-26 October 2013.

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It is difficult to get school and university students interested in physics. Many students place physics in the ‘too hard basket’. In many cases this is because physics is perceived to contain a lot of mathematics, which many students also find hard. Another barrier to the study of physics is that there is no easily identifiable career as a physicist, as for example there is for a chemist, engineer, nurse, lawyer, doctor, dentist etc. Physics touches many aspects of life. All electronic equipment, phones, computers etc contain semiconductor chips that were developed by physicists. A result of this very diverse application of physics is that physicist end up working all over the place. For example, physicists end up in private and government research laboratories, as teachers in schools and as medical physicists in hospitals.

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We report the Heck coupling of 2-vinyl-4,5-dicyanoimidazole (vinazene) with selected di- and trihalo aromatics in an effort to prepare linear and branched electron-accepting conjugated materials for application in organic electronics. By selecting the suitable halo-aromatic moiety, it is possible to tune the HOMO - LUMO energy levels, absorption, and emission properties for a specific application. In this regard, materials with strong photoluminescence from blue → green → red are reported that may have potential application in organic light-emitting diodes (OLEDs). Furthermore, derivatives with strong absorption in the visible spectrum, coupled with favorable HOMO-LUMO levels, have been used to prepare promising organic photovoltaic devices (OPVs) when combined with commercially available semiconducting donor polymers.

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Background The population exposed to potentially hazardous substances through inappropriate and unsafe management practices related to disposal and recycling of end-of-life electrical and electronic equipment, collectively known as e-waste, is increasing. We aimed to summarise the evidence for the association between such exposures and adverse health outcomes. Methods We systematically searched five electronic databases (PubMed, Embase, Web of Science, PsycNET, and CINAHL) for studies assessing the association between exposure to e-waste and outcomes related to mental health and neurodevelopment, physical health, education, and violence and criminal behaviour, from Jan 1, 1965, to Dec 17, 2012, and yielded 2274 records. Of the 165 full-text articles assessed for eligibility, we excluded a further 142, resulting in the inclusion of 23 published epidemiological studies that met the predetermined criteria. All studies were from southeast China. We assessed evidence of a causal association between exposure to e-waste and health outcomes within the Bradford Hill framework. Findings We recorded plausible outcomes associated with exposure to e-waste including change in thyroid function, changes in cellular expression and function, adverse neonatal outcomes, changes in temperament and behaviour, and decreased lung function. Boys aged 8–9 years living in an e-waste recycling town had a lower forced vital capacity than did those living in a control town. Significant negative correlations between blood chromium concentrations and forced vital capacity in children aged 11 and 13 years were also reported. Findings from most studies showed increases in spontaneous abortions, stillbirths, and premature births, and reduced birthweights and birth lengths associated with exposure to e-waste. People living in e-waste recycling towns or working in e-waste recycling had evidence of greater DNA damage than did those living in control towns. Studies of the effects of exposure to e-waste on thyroid function were not consistent. One study related exposure to e-waste and waste electrical and electronic equipment to educational outcomes. Interpretation Although data suggest that exposure to e-waste is harmful to health, more well designed epidemiological investigations in vulnerable populations, especially pregnant women and children, are needed to confirm these associations. Funding Children's Health and Environment Program, Queensland Children's Medical Research Institute, The University of Queensland, Australia.

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In order to protect the critical electronic equipment/system against damped sine transient currents induced into its cables due to transient electromagnetic fields, switching phenomena, platform resonances, etc. it is necessary to provide proper hardening. The hardness assurance provided can be evaluated as per the test CS 116 of MIL STD 461E/F in laboratory by generating & inducing the necessary damped sine currents into the cables of the Equipment Under Test (EUT). The need and the stringent requirements for building a damped sine wave current generator for generation of damped sine current transients of very high frequencies (30 MHz & 100 MHz) have been presented. A method using LC discharge for the generation has been considered in the development. This involves building of extremely low & nearly loss less inductors (about 5 nH & 14 nH) as well as a capacitor & a switch with much lower inductances. A technique for achieving this has been described. Two units (I No for 30 MHz. & 100 MHz each) have been built. Experiments to verify the output are being conducted.

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Metal oxide varistors (MOV) are popularly used to protect offline electronic equipment against power line transients. The offline switched mode power supplies (SMPS) use power line filters and MOVs in the front-end. The power line filter is used to reduce the conducted noise emission into the power line and the MOVs connected before this line filter and the MOVs connected before this line filter to clamp line transients to safer levels thereby protecting the SMPS. Because of the presence of 'X' capacitors at the input of line filter the MOV clamping voltage is increased. This paper presents one such case and gives theoretical and experimental results. An approximate method to predetermine the magnitude of such clamping voltages is also presented.

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Phase-change cooling technique is a suitable method for thermal management of electronic equipment subjected to transient or cyclic heat loads. The thermal performance of a phase-change based heat sink under cyclic heat load depends on several design parameters, namely, applied heat flux, cooling heat transfer coefficient, thermophysical properties of phase-change materials (PCMs), and physical dimensions of phase-change storage system during melting and freezing processes. A one-dimensional conduction heat transfer model is formulated to evaluate the effectiveness of preliminary design of practical PCM-based energy storage units. In this model, the phase-change process of the PCM is divided into melting and solidification subprocesses, for which separate equations are written. The equations are solved sequentially and an explicit closed-form solution is obtained. The efficacy of analytical model is estimated by comparing with a finite-volume-based numerical solution for both transient and cyclic heat loads.

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Esta pesquisa usou o estudo de caso para analisar os resíduos eletroeletrônicos gerados em uma Empresa prestadora de serviços atuante no setor naval. Após breve reflexão sobre a relação homem-natureza, apresenta-se o conceito de resíduos sólidos e suas classificações, introduzindo-se dados que embasam o impacto dos eletroeletrônicos na geração de resíduos no Brasil. Em seguida, discorre-se sobre a evolução da eletricidade e da eletrônica até os dias atuais, passando-se a comentar os aspectos e impactos da produção e descarte dos dispositivos eletroeletrônicos, que utilizam algumas substâncias tóxicas em sua manufatura. Destacam-se alguns caminhos alternativos para os resíduos eletroeletrônicos como o reuso, o reaproveitamento e a reciclagem que abriram caminhos para novos negócios. O estudo se volta para uma abordagem da legislação ambiental, mencionando aspectos da legislação dos Estados Unidos e da Europa, além de discorrer sobre fatos relevantes do ordenamento jurídico ambiental brasileiro, com ênfase na Política Nacional de Resíduos Sólidos. Esta Seção se encerra com um breve resumo do alinhamento do setor naval à legislação ambiental, através do uso das normas ISO da série 14.000. Prossegue-se com a descrição da Empresa onde se realizou o estudo de caso, apresentando-se um resumo acerca de sua trajetória, estrutura de funcionamento e a situação da gestão ambiental. Em seguida, é descrita a metodologia usada para o desenvolvimento do estudo de caso, detalhando-se os tipos de pesquisa e procedimentos utilizados para a caracterização dos resíduos eletroeletrônicos, bem como as ferramentas de gestão usadas para sua análise. Discorre-se, então, sobre o estudo de caso realizado na Empresa, com a apresentação das ações e pesquisas realizadas acerca de seus processos de geração e descarte de resíduos eletroeletrônicos. Os dados obtidos neste estudo foram analisados à luz do conhecimento ambiental e gestor e, com o auxílio de algumas ferramentas de gestão, foram selecionados os resíduos eletroeletrônicos mais impactantes e os com possibilidade de serem gerenciados pela Empresa. Encerrando o trabalho, as conclusões sobre o estudo e as sugestões para a melhoria do gerenciamento dos resíduos eletroeletrônicos são disponibilizadas para uso da Empresa, propondo-se também a implementação de um sistema de gerenciamento integrado para todos os resíduos nela gerados.

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During the last few years great changes have taken place in the fishing industry as a result of which production of fish in the world has increased enormously. From an insignificant trade employing tools and methods of primitive nature, fishing in many countries has become an important industry utilizing complex modern vessels equipped with electronic equipment and operating in the high seas with highly mechanized fishing gear.

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Ao longo das últimas décadas, a micromoldação (u-moldação) por injeção de termoplásticos ganhou um lugar de destaque no mercado de equipamentos eletrónicos e de uma ampla gama de componentes mecânicos. No entanto, quando o tamanho do componente diminui, os pressupostos geralmente aceites na moldação por injeção convencional deixam de ser válidos para descrever o comportamento reológico e termomecânico do polímero na microimpressão. Por isso, a compreensão do comportamento dinâmico do polímero à escala micro bem como da sua caraterização, análise e previsão das propriedades mecânicas exige uma investigação mais alargada. O objetivo principal deste programa doutoral passa por uma melhor compreensão do fenómeno físico intrínseco ao processo da μ-moldação por injeção. Para cumprir com o objetivo estabelecido, foi efetuado um estudo paramétrico do processo de μ-moldação por injeção, cujos resultados foram comparados com os resultados obtidos por simulação numérica. A caracterização dinâmica mecânica das μ-peças foi efetuada com o objetivo de recolher os dados necessários para a previsão do desempenho mecânico das mesmas, a longo prazo. Finalmente, depois da calibração do modelo matemático do polímero, foram realizadas análises estruturais com o intuito de prever o desempenho mecânico das μ-peças no longo prazo. Verificou-se que o desempenho mecânico das μ-peças pode ser significativamente afetado pelas tensões residuais de origem mecânica e térmica. Estas últimas, resultantes do processo de fabrico e das condições de processamento, por isso, devem ser consideradas na previsão do desempenho mecânico e do tempo de serviço das u-moldações.

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Partner selection is crucial to green supply chain management as the focal firm is responsible for the environmental performance of the whole supply chain. The construction of appropriate selection criteria is an essential, but often neglected pre-requisite in the partner selection process. This paper proposes a three-stage model that combines Dempster-Shafer belief acceptability theory and particle swarm optimization technique for the first time in this application. This enables optimization of both effectiveness, in its consideration of the inter-dependence of a broad range of quantitative and qualitative selection criteria, and efficiency in its use of scarce resources during the criteria construction process to be achieved simultaneously. This also enables both operational and strategic attributes can be selected at different levels of hierarchy criteria in different decision-making environments. The practical efficacy of the model is demonstrated by an application in Company ABC, a large Chinese electronic equipment and instrument manufacturer.

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Um dos princípios da Gestão é: “If you cannot measure it, you cannot improve it.” In The Economist – 26.Dez.2008, idea of 19th century English physicist Lord Kelvin. Embora seja uma afirmação aplicável à gestão económica, também pode ser utilizada no domínio da gestão da energia. Este trabalho surge da necessidade sentida pela empresa Continental - Industria Têxtil do Ave, S.A. em efetuar uma atualização dos seus standards de produção, minimizando os seus consumos de eletricidade e gás natural. Foi necessário efetuar o levantamento dos consumos em diversas máquinas e equipamentos industriais, caracterizando e analisando os consumos ao longo de todo o processo produtivo. Para o tratamento de dados recolhidos foi desenvolvida uma folha de cálculo em MS Office ExcelTM com metodologia adequada ao equipamento em análise, que dará apoio ao decisor para a identificação dos aspetos que melhorem o processo produtivo e garantam uma elevada eficiência energética. Porém, não se enquadra no âmbito do Plano Nacional de Racionalização de Energia, sendo uma “auditoria energética” ao processo produtivo. Recentemente, a empresa, tem vindo a utilizar equipamentos eletrónicos que permitem otimizar o funcionamento mecânico dos equipamentos e das potências instaladas dos transformadores, na tentativa de racionalizar o consumo da energia elétrica. Outros equipamentos como, conversores de frequência para controlo de motores, balastros eletrónicos que substituem os convencionais balastros ferromagnéticos das lâmpadas de descarga fluorescente, têm sido incluídos ao nível das instalações elétricas, sendo gradualmente substituída a eletromecânica pela eletrónica. Este tipo de soluções vem deteriorar as formas de onda da corrente e da tensão do sistema pela introdução de distorções harmónicas. Faz ainda parte deste trabalho, um estudo de uma solução que melhore, simultaneamente o fator de potência e reduza as harmónicas presentes num posto de transformação localizado no seio da fábrica. Esta solução, permite melhorar a qualidade da energia elétrica e as condições de continuidade de serviço, garantindo melhores condições de exploração e incrementando a produtividade da empresa.

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À cause de leur impact environnemental élevé, les déchets d’équipements électriques et électroniques (DEEE) sont un problème majeur pour les pays développés. La consommation importante de produits électroniques, dont la durée d’utilisation est de plus en plus courte, a entrainé une production croissante de DEEE. C’est dans ce contexte que l’Union européenne a instauré en 2003 la responsabilité élargie des producteurs (REP). Cet outil de politique environnementale a rendu légalement responsables les fabricants de la mise en oeuvre et du financement d’un programme d’intendance des DEEE. Alors que la REP vise principalement le traitement écologique des DEEE, cet instrument ne permet pas de réduire les quantités considérables qui sont produites par les consommateurs. Cette situation est d’autant plus inquiétante que les gains environnementaux obtenus, grâce à l’implantation de la REP, ont été annulés au regard de l’augmentation continue de la consommation de biens électroniques à l’échelle mondiale. En réponse à cette problématique, la présente thèse porte sur les pratiques de l’usager au cours de la phase de consommation des appareils électroniques (aussi appelée phase d’usage). Cette étape du cycle de vie regroupe l’achat, l’utilisation, la réparation et la mise au rebut des biens. Une approche qualitative de type exploratoire faisant appel à l’étude de cas a été utilisée. Le téléviseur, retenu comme cas d’étude, illustre des enjeux partagés par plusieurs équipements électroniques, tels que : la fréquente mise sur le marché de nouveaux modèles, le bas prix d’acquisition comparé au coût de la réparation et l’influence de la mode sur les choix effectués par le consommateur. Ces facteurs facilitent le remplacement des biens et, par conséquent, pourraient entrainer leur fin de vie prématurée qui se matérialise à travers différentes formes d’obsolescence. Dans le cadre de cette étude de cas, une trentaine d’entrevues semi-dirigées a été réalisée avec des usagers et réparateurs de produits électroniques en vue de documenter les différentes sous-étapes de la phase d’usage d’un téléviseur. Sur la base des informations recueillies, l’objectif de cette thèse est de formuler des recommandations, à destination des autorités politiques, qui pourront permettre une minimisation des impacts environnementaux liés à la phase d’usage des appareils électroniques. Les résultats ont permis de mettre en évidence, via le rôle et le statut singulier occupé par le téléviseur dans les foyers, les comportements de l’usager contribuant à augmenter l’empreinte écologique associée à la phase d’usage. L’acquisition de nombreux biens électroniques et non électroniques suite à l’achat du téléviseur, ses multiples fonctionnalités le rapprochant de celles de l’ordinateur et des tablettes, ainsi que la fin de vie prématurée de produits fonctionnels, mais obsolètes d’un point de vue technologique, font partie des résultats de cette recherche. En lien avec ces constats, cette étude propose des instruments de politique environnementale, dont l’affichage de la durée de vie des équipements électroniques, destinés à aider le consommateur à réaliser des choix plus éclairés au moment de l’achat. D’autres orientations, telles que la possibilité d’évoluer vers une réglementation horizontale, c’est-à-dire un cadre législatif qui ne se basera plus sur le produit individuel, mais sur l’ensemble des appareils ayant des fonctionnalités similaires, sont exposées. Par ailleurs, cette recherche explore certains leviers pouvant minimiser le phénomène de fin de vie prématurée des appareils électroniques, tels que l’envoi de biens obsolètes et fonctionnels des pays développés vers ceux en développement pour permettre leur réutilisation et la tendance du Do-It- Yourself dans la réparation des produits électroniques.

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Heavy metals are major toxic pollutants with severe health effects on humans. They are released into the environment from a variety of industrial activities. Cadmium, lead, zinc, chromium and copper are the most toxic metals of widespread use in industries such as tanning, electroplating, electronic equipment manufacturing and chemical processing plants. Heavy metals contribute to a variety of adverse health environmental effects due to their acute and chronic exposure through air, water and food chain. Conventional treatment methods of metal removal are often limited by their cost and ineffectiveness at low concentrations. Adsorption, the use of inactivated biomass as adsorbents offers an attractive potential alternative to their conventional methods. Mango peel and Alisma plantago aquatica are naturally occurring and abundant biomass can offer an economical solution for metal removal.The Cd(II), Pb(II), Zn(II), Cr(III) and Cu(II) adsorption by milled adsorbents of mango peel and Alisma plantago aquatica were evaluated in batches.

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Electrical gas discharges have been the subject of numerous investigations from the last century due to their growing interest in technological and fundamental applications. Absorption of electromagnetic radiation by a gas discharge result into a change in electrical impedance due to a significant perturbations in the steady state population of excited levels and the degree of ionization. This change in impedance produced by resonant absorption of radiation is known as optogalvanic COG) effect. where as that is produced by injecting electrons in to the discharge by photoelectric emission is usually known as photoemission optogalvanic (FOG) effect. With the development of lasers and sophisticated electronic equipment. these effects have established their importance in analytical and spectroscopic measurements. The present thesis deals with the work carried out by the author in the field optogalvanic effect during the past few years at the Department of Physics in Cochin University of Science| and "Fechnology. The results and the observation are summarized in nine chapters and the references to the literature is made at the end of each chapter