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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Experimental and computational investigation of forced convection cooling of rectangular blocks in a duct

Arani, Sassan Abedi January 1992 (has links)
No description available.
2

Numerical simulation of small power supply in natural convection environment

Chao, Tzu-Chuan 07 February 2012 (has links)
The power supply for electronic devises is demanded to be lighter and smaller in nowadays market. Therefore, the cooling problem becomes the major design challenge due to reduced heat transfer area. In this thesis, a numerical computation method is employed to numerically simulate the natural convection heat transfer field for a small power supply placed on the ground or table in atmospheric conditions. The effects of parameters are studied including internal heat sink structure, shell structure, heat rate of generation, body size and ground material. The results of the present study can provide design reference.
3

Customer Loyalty Analysis of Electronic Components Distributor-A Case Study of S Company

Liu, Han-Chung 04 August 2012 (has links)
With fast technical change and rapid information deliver, forcing electric products of life cycle has been reduced dramatically. Driven by market trend, causes the product development process bears squeeze. Therefore, electric component distributor is no longer engaged in the trading business, but also provides multiple services as share product features, marketing information, design application and create product add-on value. This helps customers to have products ready in the market as soon as possible. Most of electrical component manufacturers seek for more than one distributor in order to expand their own business, increase market share and decrease potential risk. At the mean time, there are many distributors investing on technical support and even preparing material without solid order for the customers demand, but the orders are still lost by slight cents difference. Thus, how to raise up the customer loyalty and repeat orders have become the important task of electric components distributor. According to nowadays industry of electric component distributor, the study of analysis of key factors affecting customer loyalty is to enhance the relationship and satisfaction as customer loyalty increase proposal and cost reduce plan for future development strategy. According to the result of research, the affecting of S company customers' loyalty is in terms of the degree of product substitutability, price, satisfaction, and the product brand.
4

Estudo dos resíduos eletroeletrônicos de uma prestadora de services do setor naval, com vistas ao gerenciamento ambiental. / Study of a naval segment Company e-waste, to environmental management.

Vanda Sueli Mondego 13 March 2012 (has links)
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. / Summary: This research has used the case study to evaluate the e-waste generated in a Company acting n the Navy segment. After a reflection about the relationship between man and nature, the concept of solid waste and its classifications is presented, commenting the impact of the electric and electronic devices in Brazilian e-waste generation. Then, the evolution of the use of electricity and electronic until current days is mentioned, commenting the environmental aspects and impacts of the production and discard of electrical and electronic equipment that are manufactured with hazardous substances. Highlighting some alternatives ways to reuse, recovery and recycling that create new kind of business. The research then explains the environmental policy in the US and in Europe, and then moves into important facts acts in Brazilian environmental legislation, with special attention to National Policy of Solid Residues. This part ends up with the comments about the Brazilian navy alignment to environmental policy, by using the directions of legislation ISO 14.000. After that, there is a brief about the case study Company including its trajectory, pattern of organization and environmental management situation. In the following step, is detailed the methodology that was used, which kind of survey and process were adopted to characterize the electric and electronic residues, as well the proper management tools used to analyze the results. Then, is mentioned the actions and researches were developed, about the electric and electronic components process of generation and discard, in the Company under the study case.The data from the study were performed by using the environmental and manager knowledge, selecting those with potential to impact the environment the most and, using proper management tools, being presented the achieved results. Finalizing, the conclusions about the study and the suggestions to improve the management of e-waste were available to be used by the Company, also proposing the establishment of an integrated management system to all residues generating by the Company.
5

Méthodologie d'évaluation de la sensibilité des microprocesseurs vis à vis des rayonnements cosmiques. / Evaluation methodology of microprocessor sensitivity to cosmic radiations

Houssany, Sabrine 13 September 2013 (has links)
Les circuits électroniques embarqués dans les systèmes évoluant au niveau spatial ou dans l’atmosphère sont soumis à des particules naturellement présentes qui peuvent provoquer une perturbation de leur fonctionnement. Le type d’effet lié à ces particules le plus souvent rencontré dans les composants logiques est le SEU. Cet effet correspond à l’inversion de l’état logique d’un élément de mémorisation. De nombreuses études ont été menées pour mettre au point des outils et méthodologies permettant de caractériser la sensibilité des mémoires (SRAM principalement) vis-à-vis de ce type d’effets. Néanmoins, avec l’augmentation importante de l’électronique embarquée et plus particulièrement, l’utilisation de composants de plus en plus complexes comme les microprocesseurs multicoeurs, il est devenu difficile, à l’aide des outils jusque là disponibles, de déterminer l’impact réel d’une erreur déclenchée dans un élément de mémorisation sur une application exécutée par le système électronique. L’utilisation des outils et méthodologies actuellement disponibles ne constituent alors qu'une approche pire cas : tous les éléments de mémorisation non protégés du composant sont comptabilisés et considérés comme sensibles, ce qui amène à considérer des marges importantes lors de l'analyse de risque de l'équipement. Une réduction importante de ces marges est possible en analysant le comportement dynamique de l'application opérée par le composant complexe. En effet, tous les éléments de mémorisation ne sont pas sensibles 100% du temps et de nombreux mécanismes de masquage peuvent faire en sorte qu'une erreur au niveau composant n'ait pas d'incidence sur l'application. Ce sujet de thèse aboutira à la mise au point d'un outil permettant de connaitre avec plus de précisions la sensibilité réelle d'une application opérée sur un microprocesseur, en vue d'optimiser les protections nécessaires et plus particulièrement, de tirer profit de l’architecture spécifique des microprocesseurs multicoeurs. Pour réaliser cette étude, les axes suivants seront investigués : - Étude de l’architecture des microprocesseurs - Utilisation des modèles de performance de processeurs - Utilisation des techniques d’émulation par FPGA - Analyse logicielle du code de l’application Des validations expérimentales sous laser et faisceau de particules seront également réalisées. / The electronic circuits embarked on the systems evolving in the spatial level or in the atmosphere are subjected(submitted) to naturally present particles which can cause(provoke) a disturbance of their functioning. The type(chap) of effect bound(connected) to these particles most of the time met in the logical components is the SEU. This effect corresponds to the inversion of the logical state of an element of memorization. Numerous studies were led to finalize(to work out) tools and methodologies allowing to characterize the sensibility of reports(memoirs) (SRAM mainly) towards this type(chap) of effects. Nevertheless, with the important increase of the embarked electronics and more particularly, the use of more and more complex components as microprocessors multihearts, he(it) became
6

Estudo dos resíduos eletroeletrônicos de uma prestadora de services do setor naval, com vistas ao gerenciamento ambiental. / Study of a naval segment Company e-waste, to environmental management.

Vanda Sueli Mondego 13 March 2012 (has links)
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. / Summary: This research has used the case study to evaluate the e-waste generated in a Company acting n the Navy segment. After a reflection about the relationship between man and nature, the concept of solid waste and its classifications is presented, commenting the impact of the electric and electronic devices in Brazilian e-waste generation. Then, the evolution of the use of electricity and electronic until current days is mentioned, commenting the environmental aspects and impacts of the production and discard of electrical and electronic equipment that are manufactured with hazardous substances. Highlighting some alternatives ways to reuse, recovery and recycling that create new kind of business. The research then explains the environmental policy in the US and in Europe, and then moves into important facts acts in Brazilian environmental legislation, with special attention to National Policy of Solid Residues. This part ends up with the comments about the Brazilian navy alignment to environmental policy, by using the directions of legislation ISO 14.000. After that, there is a brief about the case study Company including its trajectory, pattern of organization and environmental management situation. In the following step, is detailed the methodology that was used, which kind of survey and process were adopted to characterize the electric and electronic residues, as well the proper management tools used to analyze the results. Then, is mentioned the actions and researches were developed, about the electric and electronic components process of generation and discard, in the Company under the study case.The data from the study were performed by using the environmental and manager knowledge, selecting those with potential to impact the environment the most and, using proper management tools, being presented the achieved results. Finalizing, the conclusions about the study and the suggestions to improve the management of e-waste were available to be used by the Company, also proposing the establishment of an integrated management system to all residues generating by the Company.
7

Estudo experimental da transferência de calor em um dissipador de microcanais e água como fluido refrigerante

Silva, Jonatan Silva da 17 July 2017 (has links)
Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-11-13T12:25:17Z No. of bitstreams: 1 Jonatan Silva da Silva_.pdf: 2236357 bytes, checksum: f3eae6a5cb0b0488ccdd0eaa3d372692 (MD5) / Made available in DSpace on 2017-11-13T12:25:17Z (GMT). No. of bitstreams: 1 Jonatan Silva da Silva_.pdf: 2236357 bytes, checksum: f3eae6a5cb0b0488ccdd0eaa3d372692 (MD5) Previous issue date: 2017-07-17 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / Com o avanço da tecnologia, os circuitos eletrônicos são fabricados em tamanhos cada vez menores e com maior potência de processamento de dados. Atualmente os chips estão sendo produzidos em pequenas áreas, com mais de 1010 transistores encapsulados, o que causa aumento de calor gerado e assim elevação da temperatura de operação. A elevada temperatura é responsável pelo aumento de falhas e ocasiona a diminuição da eficiência dos mesmos. As falhas mais frequentes causadas pelo aquecimento dos circuitos integrados são o aumento do estresse mecânico nas juntas de solda, que podem quebrar ou romper contatos por fadiga térmica; incompatibilidade de expansão térmica dos diferentes materiais; a modificação do desempenho elétrico do dispositivo; o aumento de correntes de fuga, a aceleração do processo de corrosão e a ocorrência de eletro migração. Devido a isso, o presente trabalho apresenta uma análise experimental de um sistema de microcanais com escoamento de fluido monofásico, água, para a dissipação de calor e, portanto, a diminuição da temperatura de um sistema, que representa uma placa de circuito com componentes eletrônicos. Os microcanais foram desenvolvidos em uma fita adesiva e termocondutiva dupla face com uso de uma impressora de corte. O dispositivo mede 50 x 70 mm e possui 10 microcanais paralelos de seção retangular com 800 µm de largura e 400 µm de altura, resultando em um diâmetro hidráulico do canal de escoamento de 533 µm. Testes são realizados para diferentes fluxos de calor e vazões de líquido. Os resultados demonstraram que houve diminuição das temperaturas da parede comparando as velocidades mássicas, obtendo-se uma variação média de 10,2 °C quando modificado a velocidade mássica de 51,2 kg/m²s para 102,4 kg/m²s, onde o fluido refrigerante apresentou uma redução de 27,5 °C. / With the advancement of technology, electronic circuits are manufactured in ever smaller sizes and with greater data processing power. Currently chips are being produced in small areas, with more than 1010 encapsulated transistors, which causes increased heat generated and thus elevated operating temperature. The high temperature is responsible for the increase of faults and causes the decrease of their efficiency. The most frequent faults caused by the heating of the integrated circuits are the increase of the mechanical stress in the joints of weld, that can break or break contacts by thermal fatigue; Incompatibility of thermal expansion of different materials; Modifying the electrical performance of the device; The increase of leakage currents, the acceleration of the corrosion process and the occurrence of electro migration. Due to this, the present work presents an experimental analysis of a system of microchannels with single phase fluid flow, water, for the dissipation of heat and, therefore, the decrease of the temperature of a system, representing a circuit board with electronic transistors. The microchannels were developed in a double-sided thermo-conductive adhesive tape using a cut-off printer. The device measures 50 x 70 mm and has 10 parallel microchannels of rectangular section with 800 μm wide and 400 μm in height, resulting in a hydraulic flow channel diameter of 533 μm. Tests are performed for different heat flows and liquid flows. The results showed that there was a decrease of the wall temperatures comparing the mass velocities, obtaining a mean variation of 10.2 ° C when modified at a mass speed of 51.2 kg / m² to 102.4 kg / m², where the refrigerant showed a reduction of 27,5 °C.
8

Strategies to Minimize the Bullwhip Effect in the Electronic Component Supply Chain

Onuoha, Augustina Tina 01 January 2018 (has links)
Supply chain leaders in the information technology industry face challenges regarding their ability to mitigate amplified demand and supply variability in a supply chain network--the bullwhip effect--and reduce adverse implications on their component supply chain networks. The purpose of this multiple case study was to explore the strategies supply chain leaders in the United States used to reduce the bullwhip effect. Bullwhip effect theory served as the conceptual framework. Participants in the study were 5 purposefully selected supply chain leaders in the state of Texas who successfully implemented strategies to reduce the bullwhip effect on their networks. Data were collected from semistructured interviews and analysis of documents from the participants' websites. The data were analyzed using the 5 data analysis steps consistent with Yin's approach: collection, stratification, reassembly, interpretation, and conclusion. Four themes emerged from data analysis: (a) collaboration strategy, (b) communication strategy, (c) component shortage reduction strategy, and (d) resource management strategy. Supply chain leaders might use the findings of this study to reduce the bullwhip effect within their networks and improve their profitability. The implications for positive social change include the potential for leaders to improve environmental sustainability by using effective supply chain strategies to reduce the accumulation of excess inventories, reduce transportation fuel usage, and lessen the consumption of natural resources.
9

Analyse de performance d'un commutateur de paquets hybride opto-électronique / Performance analysis of hybrid opto-electronic packet switch

Samoud, Wiem 11 October 2016 (has links)
La fibre optique demeure le support de transmission le plus utilisé, portant le trafic à une énergie par bit relativement faible. Cependant, à cause de l’absence de mémoire toutoptique pratique, la commutation de paquets est toujours exécutée électriquement. Les conversions Optiques Électriques Optiques (O-E-O) nécessaires font de la commutation l’un des domaines les plus consommateurs d’énergie. Ce problème est de plus en plus important spécialement avec la croissance exponentielle du trafic dans les réseaux optiques. Un défi majeur à prendre en considération dans la conception de futurs réseaux optiques est la restriction de leur consommation énergétique. De ce fait, dans le cadre de cette thèse, nous étudions un commutateur hybride opto-électronique qui consiste en une matrice de commutation optique complétée par une mémoire électronique partagée. L’analyse de performance prenant en compte différentes classes de service, distributions de paquets et méthodes de connectivité du commutateur (canaux WDMet/ou SDM), montre que, grâce aux stratégies de commutation établies, le commutateur hybride répond aux besoins de toutes les classes de service en termes de taux de perte de paquets, la charge durable du système et la latence. De plus, il réduit significativement les conversions O-E-O par rapport aux commutateurs électriques commercialisés, puisqu’ils n’auront lieu que pour les paquets mis en mémoire d’attente. Nous défendons que le commutateur de paquets hybride opto-électronique satisfait les exigences en qualité de service et pourrait être une solution prometteuse pour réduire la consommation d’énergie des réseaux optiques. / Most transmission systems are based on optical fibers, carrying the traffic at a relatively low energy per bit. However, due to the lack of mature optical buffers, packet switching is still performed electrically. The required Optical-Electrical-Optical (O-E-O) conversions make the switching one of the areas with the fastest-growing energy consumption. A major challenge that must be met in designing future optical networks is curbing their energy consumption. Therefore, within this thesis, we investigate a hybrid optoelectronic switch which consists of an optical switching matrix supplemented with a shared electronic buffer. Performance analysis taking into account different classes of service, packet classifications and switch connectivity methods (WDM and/or SDM channels), shows that, thanks to the established switching strategies, the hybrid switch satisfies the requirements of all the different classes of service in terms of Packet Loss Rate, sustainable system load and latency. Moreover, it significantly reduces the O-E-O conversions compared to commercial off-the-shelf electrical switches, since they occur only for buffered packets. We defend that the hybrid opto-electronic packet switch meets the requirements on quality of service and could be a promising solution to reduce the energy consumption of optical networks.
10

電子零件通路商在非直販模式下的訂單決策研究-以ABC公司為例 / The Study of Order Decisions under Indirect Selling Model of an Electronic Component Distributor-taking ABC Company as an Example

蕭博修, Hsiao, Po Hsiu Unknown Date (has links)
電子零件通路商在電子零件產業中扮演協調的角色,需要調解上游供應商與下游顧客,減少市場供給與需求間的差距。ABC公司,為亞洲市場數一數二的電子零件通路商,負責企業間的配銷工作,在整體供應鏈中具有緩衝的作用。 ABC公司有兩個主要的銷售模式:非直販與直販模式。兩者差異在於負責訂單管理流程中的角色不同。非直販模式有兩個主要角色:銷售員Sales與產品經理PM (Product Managers)。Sales需負責將產品售出,而PM則負責訂單的達交、履行。而直販模式則只需PM來處理所有訂單或銷售相關的業務。在非直販模式下,Sales的訂單需要經由PM審核通過才算成立。而在訂單要求被拒絕的同時可能造成兩者間的衝突產生。Sales傾向盡可能的銷售較多的產品來達到預期的目標,而PM則需顧慮相應訂單產生的剩餘產品所造成的庫存水準提升的風險。這種情況在訂單履行的問題中非常常見。一般來說,公司會考量訂單達交的預算,包含為了完成此筆訂單的其他成本,如額外的附加運送成本,而Sales通常會被鼓勵採用“Sell what you have”的銷售策略來販售產品以避免額外的庫存產生。 為此,本研究想得知電子零件通路商如何在非直販模式下作訂單決策,釐清它的訂單流程並進一步瞭解影響訂單決策的重要因素。本研究採用訪談作為主要研究方法,透過與與個案公司的Sales與PM的訪談,整理了在非直販模式下的訂單流程與不同的訂單履行策略。本研究成果可幫助企業瞭解非直販模式的接單流程,以及決策所需考量的變數與其影響,有助於提升企業的知識管理功能。

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