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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.
241

Power allocation and cell association in cellular networks

Ho, Danh Huu 26 August 2019 (has links)
In this dissertation, power allocation approaches considering path loss, shadowing, and Rayleigh and Nakagami-m fading are proposed. The goal is to improve power consumption, and energy and throughput efficiency based on user target signal to interference plus noise ratio (SINR) requirements and an outage probability threshold. First, using the moment generating function (MGF), the exact outage probability over Rayleigh and Nakagami-m fading channels is derived. Then upper and lower bounds on the outage probability are derived using the Weierstrass, Bernoulli and exponential inequalities. Second, the problem of minimizing the user power subject to outage probability and user target SINR constraints is considered. The corresponding power allocation problems are solved using Perron-Frobenius theory and geometric programming (GP). A GP problem can be transformed into a nonlinear convex optimization problem using variable substitution and then solved globally and efficiently by interior point methods. Then, power allocation problems for throughput maximization and energy efficiency are proposed. As these problems are in a convex fractional programming form, parametric transformation is used to convert the original problems into subtractive optimization problems which can be solved iteratively. Simulation results are presented which show that the proposed approaches are better than existing schemes in terms of power consumption, throughput, energy efficiency and outage probability. Prioritized cell association and power allocation (CAPA) to solve the load balancing issue in heterogeneous networks (HetNets) is also considered in this dissertation. A Hetnet is a group of macrocell base stations (MBSs) underlaid by a diverse set of small cell base stations (SBSs) such as microcells, picocells and femtocells. These networks are considered to be a good solution to enhance network capacity, improve network coverage, and reduce power consumption. However, HetNets are limited by the disparity of power levels in the different tiers. Conventional cell association approaches cause MBS overloading, SBS underutilization, excessive user interference and wasted resources. Satisfying priority user (PU) requirements while maximizing the number of normal users (NUs) has not been considered in existing power allocation algorithms. Two stage CAPA optimization is proposed to address the prioritized cell association and power allocation problem. The first stage is employed by PUs and NUs and the second stage is employed by BSs. First, the product of the channel access likelihood (CAL) and channel gain to interference plus noise ratio (GINR) is considered for PU cell association while network utility is considered for NU cell association. Here, CAL is defined as the reciprocal of the BS load. In CAL and GINR cell association, PUs are associated with the BSs that provide the maximum product of CAL and GINR. This implies that PUs connect to BSs with a low number of users and good channel conditions. NUs are connected to BSs so that the network utility is maximized, and this is achieved using an iterative algorithm. Second, prioritized power allocation is used to reduce power consumption and satisfy as many NUs with their target SINRs as possible while ensuring that PU requirements are satisfied. Performance results are presented which show that the proposed schemes provide fair and efficient solutions which reduce power consumption and have faster convergence than conventional CAPA schemes. / Graduate
242

Quantitative Risk Assessment for Residential Mortgages

Ren, Qingyun 01 May 2017 (has links)
The crisis of the mortgage market and the mortgage-backed security (MBS) market in 2008 had dramatic negative effects in dragging down all of the economy on a worldwide scale. Many researches have, therefore, attempted to explore the influencing factors on mortgage default risk. This project, in cooperation with the company EnerScore, revolves around discovering a correlation between portfolios of mortgages to underlying energy expenditures. EnerScore€™s core product provides an internal dataset related to home energy efficiency for American homes and gives their corresponding home energy efficiency rating to every home, which is called an €œEnerScore.€� This project involves discovering a correlation between default within portfolios of mortgages based on underlying energy expenditures. The goal is to show that energy efficient homes potentially have lower default risks than standard homes because the homes which lack energy efficiency are associated with higher energy costs. This leaves less money to make the mortgage payment, and thereby increases default risk. The first phase of this project involves finding a foreclosure dataset that will be used to design the quantitative model. Due to limited availability and constraints related to default data, Google search query data is used to develop a broad based and real-time index of mortgage default risk and establish a meaningful scientific correlation. After analyzing several statistical models to explore this correlation, the regression tree model showed that the EnerScore is a strong predictor for mortgage default risk when using city-level mortgage default risk data and EnerScore data.
243

Exploration of Energy Efficient Hardware and Algorithms for Deep Learning

Syed Sarwar (6634835) 14 May 2019 (has links)
<div>Deep Neural Networks (DNNs) have emerged as the state-of-the-art technique in a wide range of machine learning tasks for analytics and computer vision in the next generation of embedded (mobile, IoT, wearable) devices. Despite their success, they suffer from high energy requirements both in inference and training. In recent years, the inherent error resiliency of DNNs has been exploited by introducing approximations at either the algorithmic or the hardware levels (individually) to obtain energy savings while incurring tolerable accuracy degradation. We perform a comprehensive analysis to determine the effectiveness of cross-layer approximations for the energy-efficient realization of large-scale DNNs. Our experiments on recognition benchmarks show that cross-layer approximation provides substantial improvements in energy efficiency for different accuracy/quality requirements. Furthermore, we propose a synergistic framework for combining the approximation techniques. </div><div>To reduce the training complexity of Deep Convolutional Neural Networks (DCNN), we replace certain weight kernels of convolutional layers with Gabor filters. The convolutional layers use the Gabor filters as fixed weight kernels, which extracts intrinsic features, with regular trainable weight kernels. This combination creates a balanced system that gives better training performance in terms of energy and time, compared to the standalone Deep CNN (without any Gabor kernels), in exchange for tolerable accuracy degradation. We also explore an efficient training methodology and incrementally growing a DCNN to allow new classes to be learned while sharing part of the base network. Our approach is an end-to-end learning framework, where we focus on reducing the incremental training complexity while achieving accuracy close to the upper-bound without using any of the old training samples. We have also explored spiking neural networks for energy-efficiency. Training of deep spiking neural networks from direct spike inputs is difficult since its temporal dynamics are not well suited for standard supervision based training algorithms used to train DNNs. We propose a spike-based backpropagation training methodology for state-of-the-art deep Spiking Neural Network (SNN) architectures. This methodology enables real-time training in deep SNNs while achieving comparable inference accuracies on standard image recognition tasks.</div>
244

Právní úprava energetické účinnosti v Evropské unii / The Legislation Governing Energy Efficiency in the European Union

Štípa, Martin January 2018 (has links)
THE TITLE OF THE DIPLOMA THESIS AND ABSTRACT TITLE: The Legislation Governing Energy Efficiency in the European Union ABSTRACT: The European Union's energy policy has undergone a major transformation over the last few years. The interest in ensuring sustainability, self-sufficiency, competitiveness and secure energy supplies leads to deeper energy integration among Member States. High energy efficiency is an ideal tool for achieving these particular objectives because its basic principle is to provide more services while using the same or even less energy. As a result, a variety of conceptual instruments and relevant legislation have been revised over the last few years, which was accompanied by a conflict of interest between various stakeholders and the adoption of less than ideal compromise solutions. This diploma thesis aims to evaluate the current legislation on energy efficiency in the European Union, including its development. The thesis is divided into three parts, the first of which represents the initial theoretical basis that aims to define the basic concepts and indicators of energy efficiency. The second part deals with the strong link between environmental protection and energy efficiency while emphasizing the importance of fundamental environmental principles that are reflected in the...
245

Estudo sobre a viabilidade e o desempenho de um coletor solar com transmissão de luz em fibra óptica para a iluminação natural em ambientes / Study on the feasibility and performance of a solar collector with fiber optic light transmission for natural lighting in ambients

Leite, Aline Gouvêa 25 October 2018 (has links)
A iluminação dos espaços é observada há milênios, desde a utilização do fogo até as mais novas tecnologias em iluminação. Iluminar ambientes procurando, cada vez mais, a eficiência e a economia de energia vem sendo motivo de investigação constante dos pesquisadores. Atualmente, o grande problema enfrentado pela iluminação artificial é o custo da energia elétrica e por isso vários pesquisadores têm procurado soluções alternativas. O presente trabalho realizou um estudo sobre a viabilidade técnica e o desempenho de um equipamento (patenteado como Girassol®) que emprega a fibra óptica para iluminação natural em ambientes que não recebem luz direta, ainda no formato de um protótipo. O aspecto da sustentabilidade visando a economia de energia através da captação solar e condução da luz através dos cabos de fibra óptica até a célula-teste foi analisado. A questão principal a ser observada foi quão eficiente pode ser o sistema de iluminação com fibra óptica utilizando a captação de luz solar. Para isso foram feitos testes do equipamento em um ambiente previamente construído, denominado célula teste, com área aproximada de 4 m². Foi medida a quantidade de luminância e iluminâncias que chegam ao ambiente da célula-teste. Esta pesquisa visou conhecer a tecnologia atual existente no mercado comercial nacional e internacional e a tecnologia do equipamento desenvolvido no Brasil. A pesquisa considerou como a hipótese de que a correta captação de luz solar aliada à correta condução através dos cabos de fibra óptica, que permite com que a iluminação em ambientes iluminados somente com luz artificial passem a ser iluminados com a luz natural conduzida pelos cabos de fibra óptica, pode colaborar para a qualidade da luz para seus usuários e para a eficiência energética da edificação. A metodologia desenvolvida foi através de medições uma vez por semana, durante um ano, três vezes ao dia (às 9, 12 e 15 horas) comprovando a eficiência do equipamento na diversidade de situações impostas por intempéries. Os resultados obtidos comprovaram a viabilidade técnica e o bom desempenho do equipamento confirmando sua potencialidade de contribuição para a eficiência energética quando implantado. Este estudo contribuiu para a comunidade acadêmica por sua interdisciplinaridade e por apresentar avanço em conhecimentos técnicos e teóricos sobre o melhor aproveitamento da luz natural para obtenção de eficiência energética, tema de grande interesse frente a questões estéticas, ambientais e de saúde.\" / The lighting of spaces has been observed for millennia, since the use of fire up the latest lighting technologies. Lighting environments increasingly looking for efficiency and energy being a reason for constant research of the researchers. Currently, the major problem faced by artificial lighting is the cost of electrical energy and that is why several researchers have sought solutions alternatives. The present work carried out a study on the viability technique and the performance of an equipment (patented as Girassol®) that fiber optics for natural lighting in receive direct light, still in the shape of a prototype. The sustainability to save energy through solar and conduction of light through fiber optic cables to the test cell It was analyzed. The main issue to note was how efficient can be the lighting system with fiber optics using the capture of sunlight. For this, equipment tests were performed in a previously constructed environment, called the test cell, with an approximate area of 4sqm. The amount of luminance and illuminances that reached the environment of the test cell. This research aimed to know the technology existing in the national and international commercial market and the equipment technology developed in Brazil. The research considered as the hypothesis that the correct capture of sunlight allied to the correct through fiber optic cables, which allows illuminated areas with only artificial light be illuminated with natural light led by fiber optic cables, can collaborate on the quality of light for its users and for the energy efficiency of the building. The methodology developed was through measurements once a week, for one year, three times (9 am, 12 pm, and 3 pm), demonstrating the efficiency of the equipment in the diversity of situations imposed by inclement weather. The obtained results proved the technical feasibility and good performance of the equipment confirming its potential contribution to efficiency when implanted. This study contributed to the its interdisciplinarity and to present advances in technicians and theorists about the best use of natural light to obtain energy efficiency, a subject of great interest in aesthetic, environmental and health matters.
246

Análise de viabilidade financeira para obtenção de créditos de carbono em projetos de eficiência energética. / Analysis of financial viability to obtain carbon credits in energy efficiency projects.

Gedra, Ricardo Luís 07 May 2009 (has links)
O presente trabalho tem por objetivo analisar a viabilidade financeira para obtenção de créditos de carbono em projetos de eficiência energética, por meio dos indicadores financeiros Valor Presente Líquido (VPL) e Taxa Interna de Retorno (TIR). A partir do desenvolvimento de uma modelagem analítica composta de despesas e receitas existentes em um determinado horizonte de tempo, obtém-se o fluxo caixa resultante do projeto, sobre o qual é calculado o VPL e a TIR em diferentes cenários de receitas advindas da venda dos créditos de carbono. Desta forma, pretende-se apresentar em quais condições a obtenção dos créditos de carbono aumenta o desempenho financeiro de um projeto de eficiência energética e em quais condições este desempenho é reduzido. / The present work has for objective to analyze the financial viability to obtain carbon credits in energy efficiency projects, through the financial indicators Net Present Value (NPV) and Internal Rate of Return (IRR). From the development of an analytical model composed of existing expenditure and revenue in a defined period of time, the cash flow resulting from the project is obtained, which is calculated on the NPV and IRR at different scenarios of revenue resulting from carbon credits. In such a way, it is intended to present in which conditions to obtain the carbon credits grow up the financial performance of a energy efficiency project and in which conditions this performance is reduced.
247

Avaliação dos ganhos em eficiência energética em iluminação adotando a regulamentação de etiquetagem em edificações. / Assessment of gains in energy efficiency in lighting adpting the regulation of the labeling in buildings.

Araujo, Guilherme Augusto Marques 21 September 2009 (has links)
Este trabalho tem por finalidade avaliar os ganhos em eficiência energética através da classificação de níveis, atribuídos a sistemas de iluminação das instalações, com a aplicação da proposta de regulamentação para etiquetagem voluntária do nível de eficiência energética de edificações comerciais, de serviços e públicos, em fase de homologação. Foi realizada uma contextualização da importância da referida proposta de regulamentação, com uma abordagem dos principais sistemas de avaliação de desempenho ambiental de edifícios em âmbito internacional e no Brasil, considerando as principais iniciativas e estado atual das mesmas. Com o uso da referida metodologia, foram realizados três estudos distintos: o primeiro, considerando um levantamento de dados em uma edificação existente que se caracteriza por sediar uma organização administrativa que faz parte do poder público, composta de 275 dependências. O segundo e o terceiro estudo tratam da aplicação em um projeto luminotécnico, no mesmo empreendimento, de duas luminárias distintas (compostas de sistemas ópticos com e sem aletas, respectivamente). A partir dessas atividades que norteiam a aplicação direta da metodologia para confecção de projetos, foram estabelecidas comparações entre os resultados obtidos e realizadas considerações sobre os índices de iluminância, de densidade de potência instalada total em iluminação e da densidade de potência em iluminação. De posse de todos os resultados obtidos em uma edificação com relevante representatividade no segmento dos prédios públicos, bem como das considerações pertinentes, podemos inferir que com o uso somente de iluminação geral, sem iluminação local é possível atingir no máximo a classificação B e que temos a possibilidade de uso dos dois tipos de luminárias adotadas sem alterar a classificação dos níveis de eficiência energética encontrados. / This study aims to assess the gains in energy efficiency through the classification levels, assigned to the installation of lighting systems, with the implementation of the proposed regulations for voluntary labeling of the level of energy efficiency in commercial buildings, of services and public in stage of approval. One contextualization of the importance of the proposed regulation was held with major systems for evaluating environmental of buildings in the international and Brazil, considering the major initiatives and current status of them. With the use of that methodology, three separate studies were conducted: first, considering a survey of data in an existing building which is hosting an administrative organization of the public power, composed of 275 dependences. The second and third studies dealing with the application in a lighting project in the same enterprise, in two different luminaries (composed of optical systems with and without fins, respectively). From these activities that guide the direct application of the methodology for preparation of projects there have been established comparisons between the results and made comments on the levels of illuminance, the density of total installed power in lighting and in lighting power density. In possession of all results obtained in a building with significant representation in the segment of public buildings, as well as the relevant considerations, we can infer that with the use only of general lighting, local lighting is not possible to achieve the maximum rating B and we have the possibility to use both types of luminaires adopted without changing the classification of levels of energy efficiency found.
248

Dynamic CPU frequency scaling using machine learning for NFV applications. / Escalamento dinâmico de frequência da CPU usando aprendizado de máquina em aplicações NFV.

Zorello, Ligia Maria Moreira 10 October 2018 (has links)
Growth in the Information and Communication Technology sector is increasing the need to improve the quality of service and energy efficiency, as this industry has already surpassed 12% of global energy consumption in 2017. Data centers correspond to a large part of this consumption, accounting for about 15% of energy expenditure on the Information and Communication Technology domain; moreover, the subsystem that generates the most costs for data center operators is that of servers and storage. Many solutions have been proposed to reduce server consumption, such as the use of dynamic voltage and frequency scaling, a technology that enables the adaptation of energy consumption to the workload by modifying the operating voltage and frequency, although they are not optimized for network traffic. In this thesis, a control method was developed using a prediction engine based on the analysis of the ongoing traffic. Machine learning algorithms based on Neural Networks and Support Vector Machines have been used, and it was verified that it is possible to reduce power consumption by up to 12% on servers with Intel Sandy Bridge processor and up to 21 % in servers with Intel Haswell processor when compared to the maximum frequency, which is currently the most used solution in the industry. / O crescimento do setor de Tecnologia da Informação e Comunicação está aumentando a necessidade de melhorar a qualidade de serviço e a eficiência energética, pois o setor já ultrapassou a marca de 12% do consumo energético global em 2017. Data centers correspondem a grande parte desse consumo, representando cerca de 15% dos gastos com energia do setor Tecnologia Informação e Comunicação; além disso, o subsistema que gera mais custos para operadores de data centers é o de servidores e armazenamento. Muitas soluções foram propostas a fim de reduzir o consumo de energia com servidores, como o uso de escalonamento dinâmico de tensão e frequência, uma tecnologia que permite adaptar o consumo de energia à carga de trabalho, embora atualmente não sejam otimizadas para o processamento do tráfego de rede. Nessa dissertação, foi desenvolvido um método de controle usando um mecanismo de previsão baseado na análise do tráfego que chega aos servidores. Os algoritmos de aprendizado de máquina baseados em Redes Neurais e em Máquinas de Vetores de Suporte foram utilizados, e foi verificado que é possível reduzir o consumo de energia em até 12% em servidores com processador Intel Sandy Bridge e em até 21% em servidores com processador Intel Haswell quando comparado com a frequência máxima, que é atualmente a solução mais utilizada na indústria.
249

Potencial de economia de energia em edifícios de escritórios com estratégias de ventilação híbrida / Potential of energy savings in office buildings with hybrid ventilation strategies

Brugnera, Rosilene Regolão 05 February 2014 (has links)
Grandes fachadas envidraçadas têm se tornado comuns em edifícios de escritórios, desconsiderando elementos importantes como as janelas na redução do seu consumo energético, por meio da obtenção da iluminação e ventilação naturais. Dessa forma, o objetivo principal desta pesquisa é avaliar o potencial de economia de energia em edifícios de escritórios por meio da utilização de estratégias de ventilação híbrida, em duas regiões climáticas brasileiras distintas. O método consiste em medições com sensores para aferir dados de temperatura e umidade no momento em que são acionados os condicionadores de ar, a fim de obter a temperatura de setpoint. Tal resultado foi utilizado em simulações computacionais do desempenho térmico e da iluminação natural através dos programas EnergyPlus e Daysim respectivamente. Foi analisado um modelo de edifício de escritórios, com um sistema de iluminação eficiente (dimerizável) em que foram inseridas estratégias de ventilação híbrida, a fim de se obter a influência na economia de energia devido à redução do uso do condicionamento artificial de ar (nos períodos em que isso foi possível). Os resultados apresentaram uma redução no consumo do ar condicionado em torno dos 30%, enquanto que o impacto da ventilação híbrida no consumo de energia total do edifício apresentou-se na faixa dos 12%. Todavia, com a utilização de tais estratégias alcançou-se uma redução de até 84% do desconforto térmico nos ambientes. Como conclusão do trabalho tem-se que, utilizando-se um sistema de iluminação natural eficiente, o impacto da ventilação híbrida no potencial de economia de energia, dependendo do caso, pode não ser tão expressivo, ao passo que a redução no nível de desconforto térmico é bastante significativa. / Large glazed facades have become common in office buildings and important elements, like windows to obtain natural lighting and ventilation to reduce their energy consumption have been ignored. This dissertation evaluates the potential of energy savings in office buildings through the use of hybrid ventilation strategies in two different Brazilian climatic regions. The method consists in measuring sensors for collecting humidity and temperature data at the time air conditioners are started so as to obtain the setpoint temperature. The results were used in computer simulations of both thermal performance and daylighting through EnergyPlus and Daysim software, respectively. A model of the office building, with efficient lighting (dimmable), was analyzed. Hybrid ventilation strategies were adopted for verifying the influence on energy savings due to a reduced use of artificial air conditioning (in periods in which it was possible). The results show a 30% reduction in the consumption of air conditioning and a 12% impact of hybrid ventilation on the total energy consumption of the building. However, such strategies caused an 84% reduction in the thermal discomfort in the environment. According to the results, the impact of hybrid ventilation on the potential energy savings by the use of efficient daylighting, in some cases, may not be so significant, whereas the reduction in the level of thermal discomfort is quite significant.
250

Considerações sobre a utilização do gás natural na geração de energia elétrica em Municípios da Região Amazônica / Considerations about the use of natural gas in electric energy generation in cities located in the Amazon Region.

Bonfim, Marcelo dos Santos 19 March 2008 (has links)
O suprimento de energia elétrica a municípios localizados no interior da Região Amazônica é de consecução tecnicamente complexa, de alto custo e potencialmente gerador de impactos ambientais. Tais municípios não têm grande demanda por energia elétrica, entretanto, o direito ao acesso à mesma deve ser considerado e atendido. O objetivo deste estudo é avaliar a situação atual de suprimento de energia elétrica em municípios do interior da Região Amazônica, considerando suas especificidades e necessidades, bem como apresentar uma análise sobre a utilização do gás natural na geração da energia elétrica em subsituição aos combustíveis atualmente utilizados em cada caso. Para este estudo foram selecionados sete municípios da Região Amazônica: Anamã, Anori, Caapiranga, Coari, Codajás, Iranduba e Manacapuru, que poderão ser atendidos pelo gasoduto Urucu-Manaus. / The electric energy supply to cities located in the countryside of Amazon Region is technically complex, has high cost and is potentially a cause of environmental impact. Such cities don\'t have a big demand on electric energy; however, the right of access to electric energy must be considered and attended. The objective of this study is to evaluate the present situation of the electric energy supply in cities located in the countryside of Amazon Region, considering its needs and specific characteristics, as well as to present an analysis about the uses of natural gas in electric energy generation in substitution to the fuels used in each case. For this study were selected seven cities in Amazon Region: Anamã, Anori, Caapiranga, Coari, Codajás, Iranduba, and Manacapuru, which can be attended by the Urucu-Manaus Gas Pipeline.

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