Techn. Universiẗat, Diss., 2006--Darmstadt.

Zugl.: München, Techn. Univ., Diss., 2009

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The objective of this thesis is to develop a 9.2 GHz low phase noise oscillator with a cylindrical cavity resonator. A cylindrical metal cavity with air as dielectric was used as a resonator. To minimise the phase noise of the oscillator, the resonator must be designed to have a high Q-factor. A high Q-factor was obtained by designing the resonator to operate in the TE011 mode. A tuning screw was used to tune the resonant frequency without significantly affecting the Q-factor. The tuning screw also separates the resonant frequencies of the degenerate TE011 and TM111 modes. The signal is coupled to the resonator by means of rectangular apertures. The coupling was designed to minimise the phase noise of the oscillator. A dual mode waveguide filter was developed and inserted into the oscillator loop in order to prevent oscillation at unwanted frequencies. Due to the excellent phase noise performance of the oscillator, it was not possible to measure the phase noise directly with the available phase noise meter. A measurement setup using two similar oscillators tuned to oscillate at frequencies differing by about 60 MHz was implemented. The output signals were down-converted to the difference frequency where the phase noise could be measured accurately. The output signal of the oscillator was measured at different locations in the loop and clearly showed that the resonator can be used as a filter to minimise the phase noise. The performance of the oscillators met all expectations. Phase noise levels of -115 dBc/Hz and -146 dBc/Hz were obtained at offset frequencies of 10 and 100 kHz. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om ‘n 9.2 GHz lae faseruis ossillator met 'n silindriese holte resoneerder te ontwikkel. 'n Silindriese metaal golfleier holte met 'n lug diëlektrikum was gebruik as die resoneerder. Om die faseruis van die ossillator te minimeer moet die resoneerder ontwerp word om 'n hoë Q-faktor te hê. Om 'n hoë Q-faktor te behaal was die resoneerder ontwerp om in die TE011 orde te werk. Die resoneerder is toegerus met 'n verstelskroef wat die bedryfsfrekwensie verstel sonder om die belaste Q-faktor aansienlik te beïnvloed. Die verstelskroef skei ook die frekwensie van die degeneratiewe TE011 en TM111 ordes. Drywing word na die resoneerder gekoppel deur middel van reghoekige openinge. Die koppeling is ontwerp om die faseruis van die ossillator te minimeer. 'n Tweede orde dubbelmodes golfleier filter is ontwerp en in die ossillatorlus ingevoeg om ossillasie by ongewenste frekwensies te voorkom. Vanweë die baie lae faseruis van die ossillator was dit nie moontlik om die faseruis direk met die beskikbare faseruismeter te meet nie. 'n Meetopstelling met twee soorgelyke ossillators waarvan die frekwensies met ongeveer 60 MHz verskil is geïmplementeer. Die uittreeseine van die ossillators is afgemeng na die verskilfrekwensie waar die meetinstrument meer sensitief is en die faseruis akkuraat gemeet kan word. Die uittreesein van die ossillator is by verskillende punte gemeet en het duidelik getoon dat die resoneerder as filter gebruik kan word om die faseruis te minimeer. Die ossillators se werkverrigting het aan die verwagtinge voldoen. Faseruis vlakke van -115 dBc/Hz en -146 dBc/Hz by afsetfrekwensies van onderskeidelik 10 en 100 kHz is verkry.

Orientador: Fábio Bertequini Leão / Resumo: No contexto de gestão e conservação de energia elétrica, ferramentas de apoio ao consumidor para gerenciar sua demanda são fundamentais para a otimização do uso dos recursos energéticos de modo a minimizar os custos com energia elétrica e ao mesmo tempo garantir o conforto do consumidor, considerando que este consumidor esteja inserido em um ambiente de Gerenciamento pelo Lado da Demanda (GLD). Assim, este trabalho propõe um novo modelo matemático de programação linear inteira mista (PLIM) para resolver o problema de gerenciamento ótimo de energia elétrica pelo lado do consumidor. O modelo matemático é baseado na minimização do custo da energia elétrica e maximização do conforto do consumidor, levando em conta a minimização da diferença entre o consumo habitual e o consumo ótimo, e a minimização da potência absorvida da rede. O modelo é implementado em linguagem de programação AMPL e resolvido utilizando o solver CPLEX. A metodologia é aplicada para gerenciar um conjunto de cargas típicas residenciais e os resultados mostram sua eficiência e potencial para gerenciar de forma ótima a demanda do consumidor, considerando a tarifa de energia elétrica com preço variável, geração distribuída, armazenamento de energia em banco de baterias e veículos elétricos. / Abstract: In the context of the management and conservation of electric energy, consumer support tools to manage their demand are fundamental for optimizing the use of energy resources in order to minimize energy costs and at the same time guarantee consumer comfort, considering that the consumer is inserted in a Demand Response (DR) environment. Thus, this work proposes a new mathematical model of mixed integer linear programming (MILP) to solve the problem of optimal management of electrical energy by the consumer side. The mathematical model is based on minimizing the cost of electrical energy, maximizing consumer comfort, taking into account the minimization of the difference between habitual consumption and optimal consumption, and minimizing the power consumed by the network. The model is implemented in AMPL programming language and solved using the CPLEX solver. The methodology is applied to manage a set of typical residential loads and the results show its efficiency and potential to optimally manage the consumer demand, considering the price of electricity with variable price, distributed generation, storage of energy in bank of batteries and electric vehicles. / Mestre

No description available.

abstract: This research develops heuristics to manage both mandatory and optional network capacity reductions to better serve the network flows. The main application discussed relates to transportation networks, and flow cost relates to travel cost of users of the network. Temporary mandatory capacity reductions are required by maintenance activities. The objective of managing maintenance activities and the attendant temporary network capacity reductions is to schedule the required segment closures so that all maintenance work can be completed on time, and the total flow cost over the maintenance period is minimized for different types of flows. The goal of optional network capacity reduction is to selectively reduce the capacity of some links to improve the overall efficiency of user-optimized flows, where each traveler takes the route that minimizes the traveler’s trip cost. In this dissertation, both managing mandatory and optional network capacity reductions are addressed with the consideration of network-wide flow diversions due to changed link capacities. This research first investigates the maintenance scheduling in transportation networks with service vehicles (e.g., truck fleets and passenger transport fleets), where these vehicles are assumed to take the system-optimized routes that minimize the total travel cost of the fleet. This problem is solved with the randomized fixed-and-optimize heuristic developed. This research also investigates the maintenance scheduling in networks with multi-modal traffic that consists of (1) regular human-driven cars with user-optimized routing and (2) self-driving vehicles with system-optimized routing. An iterative mixed flow assignment algorithm is developed to obtain the multi-modal traffic assignment resulting from a maintenance schedule. The genetic algorithm with multi-point crossover is applied to obtain a good schedule. Based on the Braess’ paradox that removing some links may alleviate the congestion of user-optimized flows, this research generalizes the Braess’ paradox to reduce the capacity of selected links to improve the efficiency of the resultant user-optimized flows. A heuristic is developed to identify links to reduce capacity, and the corresponding capacity reduction amounts, to get more efficient total flows. Experiments on real networks demonstrate the generalized Braess’ paradox exists in reality, and the heuristic developed solves real-world test cases even when commercial solvers fail. / Dissertation/Thesis / Doctoral Dissertation Industrial Engineering 2017

Submitted by GUILHERME BRANDÃO MARTINS null (guilherme-bm@outlook.com) on 2016-06-09T18:22:45Z No. of bitstreams: 1 Dissertacao_Guilherme_Brandão_Martins.pdf: 11362535 bytes, checksum: c1da2ab3e80ead0846eae49d9a1bc40e (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-13T17:06:19Z (GMT) No. of bitstreams: 1 martins_gb_me_sjrp.pdf: 11362535 bytes, checksum: c1da2ab3e80ead0846eae49d9a1bc40e (MD5) / Made available in DSpace on 2016-06-13T17:06:19Z (GMT). No. of bitstreams: 1 martins_gb_me_sjrp.pdf: 11362535 bytes, checksum: c1da2ab3e80ead0846eae49d9a1bc40e (MD5) Previous issue date: 2016-05-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Com os avanços relacionados às tecnologias de redes computacionais e armazenamento de dados observa-se que, atualmente, uma grande quantidade de conteúdo digital está sendo disponibilizada via internet, em especial por meio de redes sociais. A fim de explorar esse contexto, abordagens relacionadas ao processamento e apredizado de padrões em vídeos têm recebido crescente atenção nos últimos anos. Sistemas de recomendação de filmes, amplamente empregados em lojas virtuais, são umas das principais aplicações no que se refere aos avanços de pesquisa na área de processamento de vídeos. Com o objetivo de acelerar o processo de recomendação e redução de armazenamento, técnicas para classificação e sumarização de vídeos por meio de aprendizado de máquina têm sido utilizadas com o intuito de explorar conteúdo informativo e também redundante. Por meio de técnicas de agrupamento e descrição de dados, é possível identificar quadros-chave de um conjunto de amostras a fim de que, posteriormente, estes sejam usados para sumarização do vídeo. Além disso, por meio de bases de vídeos rotuladas, podemos classificar amostras de modo a organizá-las por gêneros de vídeo. O presente trabalho objetiva utilizar o classificador Floresta de Caminhos Ótimos para sumarização automática e classificação de vídeos por gênero, bem como o estudo de sua viabilidade nestes contextos. Os resultados obtidos mostram que o referido classificador obteve desempenhos bastante promissores e próximos à algumas das técnicas de sumarização automática e classificação de vídeos que, atualmente, representam o estado-da-arte no atual contexto. / Currently, a number of improvements related to computational networks and data storage technologies have allowed a considerable amount of digital content to be provided on the internet, mainly through social networks. In order to exploit this context, video processing and pattern recognition approaches have received a considerable attention in the last years. Movie recommendation systems are widely employed in virtual stores, thus being one of the main applications regarding to research advances in the video processing field. Aiming to boost the content recommendation and storage cutback, different video categorization and video summarization techniques have been applied to handle with more informative and redundant content. By availing clustering and data description techniques, it is possible to identify keyframes from a given sample collection in order to consider them as part of the video summarization process. Furthermore, through labeled video data collections it is possible to classify samples in order to arrange them by video genres. The main goal of this work is to employ the Optimum-Path Forest classifier in both video summarization and video genre classification processes as well as to conduct a viability study of such classifier in the aforementioned contexts. The results have shown this classifier can achieve promising performances, being very close in terms of summary quality and consistent recognition rates to some state-of-the-art video summarization and classification approaches.

Submitted by LUÍS CARLOS SANCHEZ null (luissanchez-123@hotmail.com) on 2017-09-15T15:17:01Z No. of bitstreams: 1 DISSERTAÇÃOLUISCARLOSSANCHEZ.pdf: 2890277 bytes, checksum: cfea2bf60d40685c6c36c43b6e60fd5b (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-15T15:21:08Z (GMT) No. of bitstreams: 1 sanchez_lc_me_ilha.pdf: 2890277 bytes, checksum: cfea2bf60d40685c6c36c43b6e60fd5b (MD5) / Made available in DSpace on 2017-09-15T15:21:08Z (GMT). No. of bitstreams: 1 sanchez_lc_me_ilha.pdf: 2890277 bytes, checksum: cfea2bf60d40685c6c36c43b6e60fd5b (MD5) Previous issue date: 2017-07-14 / No contexto de gestão e conservação de energia elétrica, ferramentas de apoio ao consumidor para gerenciar sua demanda são fundamentais para a otimização do uso dos recursos energéticos de modo a minimizar os custos com energia elétrica e ao mesmo tempo garantir o conforto do consumidor, considerando que este consumidor esteja inserido em um ambiente de Gerenciamento pelo Lado da Demanda (GLD). Assim, este trabalho propõe um novo modelo matemático de programação linear inteira mista (PLIM) para resolver o problema de gerenciamento ótimo de energia elétrica pelo lado do consumidor. O modelo matemático é baseado na minimização do custo da energia elétrica e maximização do conforto do consumidor, levando em conta a minimização da diferença entre o consumo habitual e o consumo ótimo, e a minimização da potência absorvida da rede. O modelo é implementado em linguagem de programação AMPL e resolvido utilizando o solver CPLEX. A metodologia é aplicada para gerenciar um conjunto de cargas típicas residenciais e os resultados mostram sua eficiência e potencial para gerenciar de forma ótima a demanda do consumidor, considerando a tarifa de energia elétrica com preço variável, geração distribuída, armazenamento de energia em banco de baterias e veículos elétricos. / In the context of the management and conservation of electric energy, consumer support tools to manage their demand are fundamental for optimizing the use of energy resources in order to minimize energy costs and at the same time guarantee consumer comfort, considering that the consumer is inserted in a Demand Response (DR) environment. Thus, this work proposes a new mathematical model of mixed integer linear programming (MILP) to solve the problem of optimal management of electrical energy by the consumer side. The mathematical model is based on minimizing the cost of electrical energy, maximizing consumer comfort, taking into account the minimization of the difference between habitual consumption and optimal consumption, and minimizing the power consumed by the network. The model is implemented in AMPL programming language and solved using the CPLEX solver. The methodology is applied to manage a set of typical residential loads and the results show its efficiency and potential to optimally manage the consumer demand, considering the price of electricity with variable price, distributed generation, storage of energy in bank of batteries and electric vehicles.

The purpose of this thesis is to carry out an empirical investigation into whether membership of monetary union matter in the determination of bank net interest margin. Bank net interest margin is the difference in bank borrowing and lending rates relative to the total interest-earning assets. We operationalise this study by comparing panels of commercial banks within and outside economic and monetary unions in Europe and Sub-Saharan Africa. For our European analysis we use bank-level data from nine Euro Area countries and seven non-Euro Area economies, in a dynamic empirical model, employing Arellano and Bover (1995)/Blundell and Bond (1998) system GMM estimation method. We find that stronger competition and efficiency, as well as greater macroeconomic stability in the Euro Area reduce bank net interest margins more than in the non-Euro Area. We attribute this to the well-developed single market with a strong socio-economic cohesion underpinning rather than the economic and monetary union. We extend the same level of analysis to the Sub-Saharan Africa, where we contrast our findings in the West African Economic and Monetary Union (WAEMU) with those of twenty non-monetary union Sub-Saharan African economies. Our findings in the Sub-Saharan African context reveal a rather different scenario. While the WAEMU enjoys relatively lower net interest margins than its non-monetary union counterparts, this is attributable to the union’s ability to pursue vigorously its primary objective of maintaining price stability by maintaining lower interest rates. Unlike in the Euro Area we do not observe a reducing impact of bank competition and efficiency on bank net interest margin in the West African Economic and Monetary Union (WAEMU) as we do in the non-monetary union Sub-Saharan Africa. We find these results for the Sub-Saharan African analysis puzzling, and attribute it to the absence of a well-developed single/common market which is supposed to drive competition and efficiency with the effect of reducing net interest margins, as it obtains in the Euro Area. Our conclusion is that it is rather the presence of a well-developed single market that engenders competition and efficiency effects to reduce bank net interest margins rather than membership of a monetary union per se.

Software measurement process is a significant part of process improvement in software organizations. The organizations usually follow a measurement process that includes measures selection, data collection, and analysis to improve their processes. Most of the software organizations face difficulties in deciding the measures to collect since there is no universal set of measures for all types of organizations and projects. Experience shows that measurement can be more successful if the measures are collected based on the goals of the organization or the project which it will serve. A few methodologies exist to aid the software organizations. Goal Question Metric (GQM) is one of the most widely known and used one. However, one of the major constraints for the organizations is the associated cost when collecting the measures. Therefore, software organizations also require selecting the optimum set of measures which are good enough for the organization. This thesis study aims to provide solution for this problem. We propose a model, named ‗Optimum Measure Set Decision Model (OMSD)‘, which is an extension of GQM paradigm. The model is based on a heuristics approach, which aims to provide the optimum set of measures from a large number of possible measures. To develop the model, we identified the factors which are significant in selecting the optimum set of measures based on the literature survey results. Then, we evaluated those factors by conducting an empirical study. As the empirical research strategy, we used traditional fixed non-experimental design strategy. We performed a survey by distributing a structured questionnaire in order to evaluate the important factors we identified when selecting the optimum number of measures to be collected in an organization. We evaluated the heuristics rules by means of some sample cases we created. Moreover, we provided an idea for an alternative solution to optimize the number of measures to be collected for the future research. / Software measurement process is a significant part of process improvement in software organizations. The organizations usually follow a measurement process that includes measures selection, data collection, and analysis to improve their processes. Most of the software organizations face difficulties in deciding the measures to collect since there is no universal set of measures for all types of organizations and projects. Experience shows that measurement can be more successful if the measures are collected based on the goals of the organization or the project which it will serve. A few methodologies exist to aid the software organizations. Goal Question Metric (GQM) is one of the most widely known and used one. However, one of the major constraints for the organizations is the associated cost when collecting the measures. Therefore, software organizations also require selecting the optimum set of measures which are good enough for the organization. This thesis study aims to provide solution for this problem. We propose a model, named ‗Optimum Measure Set Decision Model (OMSD)‘, which is an extension of GQM paradigm. The model is based on a heuristics approach, which aims to provide the optimum set of measures from a large number of possible measures. To develop the model, we identified the factors which are significant in selecting the optimum set of measures based on the literature survey results. Then, we evaluated those factors by conducting an empirical study. As the empirical research strategy, we used traditional fixed non-experimental design strategy. We performed a survey by distributing a structured questionnaire in order to evaluate the important factors we identified when selecting the optimum number of measures to be collected in an organization. We evaluated the heuristics rules by means of some sample cases we created. Moreover, we provided an idea for an alternative solution to optimize the number of measures to be collected for the future research. / Cell# 0046-762640583, 0046-762509253