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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.
321

A tomada de decisão em recursos humanos com dados replicados e inconsistentes: uma aplicação da teoria dos conjuntos aproximativos

Couto, Ayrton Benedito Gaia do January 2008 (has links)
Este estudo trata da tomada de decisão com dados replicados e inconsistentes, relativos ao universo de Recursos Humanos, em uma instituição financeira nacional. A replicação ocorre por questões técnicas e/ou econômicas, e visa o atendimento de necessidades corporativas e departamentais dessa instituição. Como metodologia de pesquisa, utilizou-se a observação direta das inconsistências e a simulação com base em dados reais que refletissem a replicação com inconsistências. A aplicação de um método multicritério fez-se necessária ante a necessidade de se tornar racional o processo de tomada de decisão, e que se transformou em elemento de motivação deste estudo. O método utilizado foi a Teoria dos Conjuntos Aproximativos (TCA), tendo em vista que nenhuma outra informação havia sobre a ocorrência de tais inconsistências. Um algoritmo foi desenvolvido para indicação das fontes principais de dados e, posteriormente, implementado em um software para agilizar a pesquisa dessas fontes. A aplicação da TCA mostrou-se uma ferramenta útil para a empresa em questão, dentre outras possíveis soluções, com o intuito de dirimir as conseqüências indesejáveis da tomada de decisão com dados replicados e inconsistentes. / This study deals about decision-making with replicated and inconsistent data, relating to the universe of Human Resources, within a domestic/local financial institution. Replication occurs because of technical and/or economic questions, and seeks to meet corporate and departmental requirements of such an institution. As research methodology, direct observation of such inconsistencies was used as well as a simulation based on actual data which would reflect replication with inconsistencies. Application of a multi-criteria method became necessary in view of the need to render the decision-making process rational, and was transformed into an element that stimulated this study. The method used was the Rough Set Theory (RST), inasmuch as there existed no other information on the occurrence of such inconsistencies. An algorithm was developed to indicate the major data sources and was subsequently implemented into a software to facilitate research of such sources. Application of the RST proved to be a useful tool for the company in question, within other possible solutions, for the purpose of preventing any unwanted consequences of decision-making with replicated and inconsistent data. / Dissertação (mestrado) - Programa de Pós-Graduação em Administração e Economia, Faculdades IBMEC, Rio de Janeiro, 2008. / Bibliografia: p. 81-84.
322

Busca em vizinhança variável aplicado na solução do problema de planejamento da expansão do sistema de transmissão de energia elétrica

Martins, Walney Andrade [UNESP] 30 November 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-30Bitstream added on 2014-06-13T18:08:29Z : No. of bitstreams: 1 martins_wa_me_ilha.pdf: 616652 bytes, checksum: e8d6346d5cc6774ab31d1538b90cb349 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho é realizada uma análise teórica, a formulação conceitual e a implementação computacional de um algoritmo de vizinhança variável aplicado ao problema de planejamento a longo prazo de sistemas de transmissão de energia elétrica. O problema de planejamento de sistemas de transmissão é um problema muito complexo de resolver porque o modelo matemático é um problema de programação não linear inteiro misto. Por outro lado, a metaheurística de vizinhança variável é uma técnica de otimização que provou excelente desempenho na resolução de problemas complexos no campo da pesquisa operacional. Assim, neste trabalho é desenvolvido um algoritmo de vizinhança variável para o problema de planejamento de sistemas de transmissão. Um conceito importante na implementação desse algoritmo é a definição de vizinhança em relação a caminhos e a técnica de redução do tamanho da vizinhança. Testes realizados mostraram um excelente desempenho do algoritmo VNS, encontrando as melhores soluções conhecidas e mostradas na literatura especializada / In this work a theoretical analysis is carried through, the conceptual formularization and the computational implementation of an applied algorithm of variable neighborhood to the problem of planning in the long run of systems of transmission of electric energy. The problem of planning of transmission systems is a very complex problem from solve because the mathematical model is a programming problem not linear. On the other hand, the metaheuristic of variable neighborhood is one technique of optimization that proved excellent performance in the resolution of complex problems in the field of the operational research. Thus, in this work is developed an algorithm of variable neighborhood for the problem of planning of transmission systems. An important concept in the implementation of this algorithm is the definition of neighborhood in relation the paths and the technique of reduction of the size of the neighborhood. Tests carried through had shown to an excellent performance of algorithm VNS, finding the best solutions known and shown in specialized literature
323

High voltage direct current strategy solving power delivery shortages to localized area of national grid

Smith, Johan January 2009 (has links)
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / The industrial and population growth of a nation can cause power delivery problems to localized areas of a national grid through their increased demand for electrical energy. One reason for these power shortages is the insufficient current carrying capacity of existing high voltage alternating current, (HVAC), transmission lines supplying the area. High voltage direct current (HVDC) transmission lines are a possible solution as they provide better power delivery than HVAC lines. New or upgraded HVAC lines, or HVDC lines or combinations of HVAC and HVDC lines are possible solutions to improve power delivery. This research investigates the various line possibilities using theory. and cutting edge frequency and time domain software tools. The challenge is how to approach this problem. What methodology or structure should be used? Thus one of the contributions of this work is the development of a strategy (flow chart), for solving power delivery problems to localized areas of a national grid through individual or combinations (e.g. parallel operation) of HVAC and/or HVDC transmission lines. The main contribution is the evaluation of a HVDC system as a solution to overcoming power delivery shortages to a localized area of a national grid. Three different software packages (two industrial and one academic) namely, PSCAD/EMTDC (time domain), DlgSILENT PowerFactory (frequency domain) and MathCAD software are evaluated for their capability to perform the simulation studies necessary to prove the possible solutions given in the developed flow chart. The PSCAD/EMTDC software package is evaluated for integrated HVAC/HVDC load flow analyses, DlgSILENT for individual and parallel combinations of HVAC lines and MathCAD to prove hand calculations to software results. Five case studies are conducted. The first case study demonstrates a healthy system with no delivery shortcomings, the second case study portrays the delivery shortcoming due to increased localized area demand, and the remaining three case studies explore possible solutions to solve the problem. The first possible solution is to construct an identical HVAC line in parallel to the existing line.
324

Data acquisition and data transfer methods for real-time power system optimisation problems solution

Deivakkannu, Ganesan January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014 / The electric power utilities play a vital role in the generation, transmission and distribution of the electrical power to the end users. The power utilities face two major issues, i.e. i) power grids are expected to operate close to the maximum capacity, and ii) there is a need for accurate and better monitoring and control of the power system network using the modern technology and the available tools. These two issues are interconnected as better monitoring allows for better control of the power system. Development of the new standard-based power system technologies contributed to raising the ideas for building of a Smart grid. The challenges are that this process requires development of new control and operation architectures and methods for data acquisition, data transfer, and control computation. These methods require data for the full dynamic state of the power system in real-time, which leads to the introduction of the synchrophasor-based monitoring and control of the power system. The thesis describes the research work and investigations for integration of the existing new power system technologies to build fully automated systems for real-time solution of power system energy management problems, incorporating data measurement and acquisition, data transfer and distribution through a communication network, and data storage and retrieval in one whole system.
325

Contribuições ao estudo de redes opticas hibridas WDM/OCDM / Contributions for the analysis of hybrid WDM/OCDM Networks

Durand, Fabio Renan 18 December 2007 (has links)
Orientadores: Edson Moschim, Marcelo Francisco Abbade / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T13:37:23Z (GMT). No. of bitstreams: 1 Durand_FabioRenan_D.pdf: 1259125 bytes, checksum: 9e123c3d511429cff5a237aefb19765c (MD5) Previous issue date: 2007 / Resumo: Neste trabalho é realizada a análise da aplicação de códigos ópticos ortgonais (OOC) da tecnologia de multiplexação por divisão de códigos ópticos (OCDM) em redes ópticas híbridas multiplexadas pela divisão de comprimentos de onda e códigos ópticos (WDM)/OCDM e em redes ópticas comutadas por rajadas (OBS). As contribuições da tese consistem da proposta e análise da aplicação da camada de transporte WDM/OCDM em redes OBS roteadas por comprimento de onda (WR-OBS), modelagem matemática de comutadores ópticos (OXC) WDM/OCDM considerando os parâmetros dos códigos OOC, estudo dos efeitos da dispersão por polarização modal (PMD) em redes ópticas WDM/OCDM e, finalmente, a proposta e análise da utilização processamento óptico da sinalização baseada em códigos OOC. Em função dos resultados obtidos se verifica que a aplicação dos códigos ópticos OOC nas redes ópticas de transporte WDM/OCDM, redes de rajadas e redes WR-OBS aumenta o desempenho destas redes por meio da diminuição da probabilidade de perdas de pacotes, latência dos pacotes e aumento da utilização da rede. Palavras-chave: Códigos ópticos ortogonais (OOC), dispersão por polarização modal (PMD), redes ópticas WDM/OCDM, redes ópticas comutadas por rajadas (OBS) / Abstract: This work presents an analysis of optical orthogonal codes (OOC) of optical code division multiplexing (OCDM) in optical networks. These networks uses the hybrid technology of wavelength division multiplexing and optical code division multiplexing (WDM/OCDM) and, optical burst switching networks (OBS). The main contributions are the analyze and propose of WDM/OCDM transport network at wavelength routed OBS networks (WR-OBS), WDM/OCDM optical crossconnects (OXC) modeling considering OOC parameters, study of polarization mode dispersion (PMD) effects in optical WDM/OCDM networks and, finally an OBS architecture with OOC label processing is analyzed. Analytical and simulation results indicate that OOC utilization in WDM/OCDM transport networks, OBS and WR-OBS networks increases the network performance by decrease of packet error rate, latency and network utilization increase. Keywords: Orthogonal optical codes (OOC), polarization mode dispersion (PMD), WDM/OCDM optical networks, optical burst switching (OBS) / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica
326

Analise da redução da latencia em redes opticas de pacotes pela diminuição no tempo de chaveamento de SOAs / Latency reduction in optical packet networks due to SOA switching time improvements

Carvalho, Raniere Noronha de 26 June 2008 (has links)
Orientador: Aldario C. Bordonalli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T21:13:22Z (GMT). No. of bitstreams: 1 Carvalho_RaniereNoronhade_M.pdf: 8840404 bytes, checksum: 8fe7c72c315d28741327bdd5e4195146 (MD5) Previous issue date: 2008 / Resumo: Atualmente, têm-se observado tentativas de se transferir o processamento da informação em redes de tráfego de pacotes cada vez mais para o domínio óptico. Isto acarretaria um aumento da quantidade de informações trocadas entre os nós da rede e promoveria a diminuição da latência do fluxo de pacotes. Com este intuito, procurou-se analisar os efeitos da redução do tempo de acionamento de uma chave óptica simples baseada em um amplificador óptico a semicondutor (SOAs) comum e disponível comercialmente no desempenho de um arranjo experimental que simulava uma rede de tráfego de pacotes. Posteriormente, de posse dos resultados obtidos, que assumiram a manutenção da integridade dos bits do pacote dentro de um fator de 10% durante os transientes de chaveamento, a latência da rede foi teoricamente avaliada. Para a melhoria do tempo de chaveamento do SOA, utilizou-se uma técnica de pré-injeção de pulso de corrente de portadores, Como esperado, houve uma redução acentuada dos tempos de acionamento de início e fim do processo de chaveamento óptico em relação ao obtido com pulsos quadrados simples, da ordem de 10 vezes. Verificou-se, também, que, acima de um determinado número de chaveamentos ocorrendo dentro de uma mesma rede óptica de pacotes, a latência da rede poderia ser diminuída de acordo com o tráfego da rede com a aplicação da técnica de redução do tempo de chaveamento do SOA. / Abstract: Currently, more and more attempts are being made to move network processing of information packets to the optical domain. This can potentially lead to an increase of the amount of information that is exchanged among nodes of the network and promote the reduction of latency of packet flow. In this sense, this work examines the effects of reducing the switching time of semiconductor optical amplifier (SOA) based switches in the performance of an experimental arrangement that simulates a network with optieal paeket traffie. By assuming per-bit paeket integrity within a factor of 10% over the switching period of transients, the latency of the network was then theoretically evaluated. j To improve the SOA switching time, a pre-impulse step injected current technique was used to provide excess carriers during transients. As result, a reduction of the order of ten times in the optical switching interval was observed in relation to that provided by ordinary square pulse~. In terms of packet traffic flow, the latency resulting from the improved SOA switching time could considerably be reduced based on the number of switching events occurring within the network. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
327

A influencia de controladores FACTS na estabilidade de angulo a pequenas pertubações de sistemas eletricos de potencia

Castro, Marcelo Silva 31 March 2005 (has links)
Orientador: Vivaldo Fernando da Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-04T02:38:10Z (GMT). No. of bitstreams: 1 Castro_MarceloSilva_M.pdf: 2888180 bytes, checksum: c1ada4e17a5c4cf84afc7096d84a2d50 (MD5) Previous issue date: 2005 / Resumo: Essa dissertação de mestrado apresenta um estudo que avalia o desempenho dos controladores FACTS (Flexible AC Transmission Systems) para a melhoria da estabilidade de ângulo a pequenas perturbações de sistemas elétricos de potência. O potencial do Modelo de Sensibilidade de Potência (MSP), uma alternativa ao clássico modelo Heffron-Phillips (MHP) para o estudo e análise do problema de oscilações eletromecânicas de baixa frequência fracamente amortecidas, é explorado. A análise da estabilidade e o projeto de estabilizadores POD (Power Oscillation Damping) para controladores FACTS são baseados em análise modal, bifurcações de Hopf, gráficos do lugar das raízes, e técnicas de resposta em frequência e no tempo. O desempenho de diferentes sinais de entrada para estabilizadores POD é investigado. Os resultados das simulações revelam que tanto os controladores FACTS série quanto os controladores em derivação possuem um grande potencial para a manutenção da estabilidade angular do sistema / Abstract: This master¿s dissertation presents an assessment of Flexible AC Transmission Systems (FACTS) controllers performance on power system small-signal angle stability improvement. The potential of the Power Sensitivity Model (PSM), an alternative approach to the classical Heffron-Phillips model (HPM) for study and analysis of poorly damped low frequency electromechanical oscillations problem, is explored. The stability analysis and design of FACTS Power Oscillation Damping (POD) controllers are based on modal analysis, Hopf bifurcations, root locus plots, and time and frequency response techniques. The performance of different input signals to the POD controllers is investigated. Simulation results reveal that both shunt FACTS controllers and series ones are very effective on keeping system angle stability / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica
328

[en] DYNAMIC SIMULATION OF HIGH VOLTAGE DIRECT CURRENT TRANSMISSION SYSTEMS IN A PERSONAL COMPUTER / [pt] SIMULAÇÃO DINÂMICA DE SISTEMAS DE TRANSMISSÃO EM CORRENTE CONTÍNUA EM MICROCOMPUTADOR DIGITAL

ANDRE LUIZ DA ROSA PLAISANT 10 August 2006 (has links)
[pt] Este trabalho trata do desenvolvimento e implementação de software destinado à simulação dinâmica de sistemas de transmissão 3m corrente contínua em microcomputador digital. A formulação matemática para a solução das equações diferenciais baseia-se nas vaiáveis de estado do sistema, e o método de integração numérica utilizado é o de Eüler Modificado. O modelo dinâmico de máquina síncrona é representado em suas grandezas de fase a, b, c. O programa digital conta, ainda, com telas gráficas para a visualização de resultados. / [en] This work is concerned with the development and implementation of a sofyware for dynamic simulation fo high voltage direct current transmission systems in a personal computer. The mathematical formulation for the solution of the diferential equations is based on the system state variables and the Modified Eüler S numerical integration method is used. The dynamic model of the synchronous machines is represented through its phase variables a, b, c. the program makes use of a compactation scheme for dealing with the sparse nature of the primitive and incidence matrices. The program also provides CTR graphic interfaces to help in the analysis of simulation results.
329

Signalling and scheduling for efficient bulk data transfer in circuit-switched networks

Grobler, Reinette 31 May 2006 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Computer Science))--University of Pretoria, 2006. / Computer Science / unrestricted
330

An investigation of protocol command translation as a means to enable interoperability between networked audio devices

Igumbor, Osedum Peter January 2014 (has links)
Digital audio networks allow multiple channels of audio to be streamed between devices. This eliminates the need for many different cables to route audio between devices. An added advantage of digital audio networks is the ability to configure and control the networked devices from a common control point. Common control of networked devices enables a sound engineer to establish and destroy audio stream connections between networked devices that are distances apart. On a digital audio network, an audio transport technology enables the exchange of data streams. Typically, an audio transport technology is capable of transporting both control messages and audio data streams. There exist a number of audio transport technologies. Some of these technologies implement data transport by exchanging OSI/ISO layer 2 data frames, while others transport data within OSI/ISO layer 3 packets. There are some approaches to achieving interoperability between devices that utilize different audio transport technologies. A digital audio device typically implements an audio control protocol, which enables it process configuration and control messages from a remote controller. An audio control protocol also defines the structure of the messages that are exchanged between compliant devices. There are currently a wide range of audio control protocols. Some audio control protocols utilize layer 3 audio transport technology, while others utilize layer 2 audio transport technology. An audio device can only communicate with other devices that implement the same control protocol, irrespective of a common transport technology that connects the devices. The existence of different audio control protocols among devices on a network results in a situation where the devices are unable to communicate with each other. Furthermore, a single control application is unable to establish or destroy audio stream connections between the networked devices, since they implement different control protocols. When an audio engineer is designing an audio network installation, this interoperability challenge restricts the choice of devices that can be included. Even when audio transport interoperability has been achieved, common control of the devices remains a challenge. This research investigates protocol command translation as a means to enable interoperability between networked audio devices that implement different audio control protocols. It proposes the use of a command translator that is capable of receiving messages conforming to one protocol from any of the networked devices, translating the received message to conform to a different control protocol, then transmitting the translated message to the intended target which understands the translated protocol message. In so doing, the command translator enables common control of the networked devices, since a control application is able to configure and control devices that conform to different protocols by utilizing the command translator to perform appropriate protocol translation.

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