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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.
21

Avaliação da operação otimizada de usinas hidrelétricas / Evaluation of the optimized operation of hydroelectric power plants

Silva, Renato Mendes da 12 December 2003 (has links)
Através da análise de estudos de otimização e simulação, considerando a operação energética das usinas existentes na cascata do rio Paranapanema, situada na região sudoeste do estado de São Paulo, mostrou-se que a operação do sistema, baseada em regras de operação obtidas através da otimização da cascata, resulta em ganhos significativos de geração e de energia armazenada, proporcionando, desse modo, uma melhor utilização de recursos hidrológicos, bem como uma condição final de armazenamento mais favorável, implicando uma operação mais eficiente e confiável de todo o sistema. / Through the analysis of optimization and simulation studies regarding the energy operation of the existing plants in the Paranapanema river, situated in the southwestern region of the state of São Paulo, Brazil, it was shown that the system operation, based on operation rules achieved considering the cascate optimization, yields significant gains of generation and stored energy in the system, therefore providing a better use of the available hydrologic resources, as well as a more favorable final storage level for each plant, which implies in a more efficient and reliable operation of the whole set.
22

Concepção otimizada de semi-submersíveis visando oscilações verticais mínimas sob excitação de ondas. / Semi-submersible optimized conception aiming heave under sea waves excitation.

Hosaas, Arnstein 13 April 2007 (has links)
Plataformas semi-submersíveis, utilizadas como estruturas flutuantes na prospecção e exploração de petróleo em águas profundas, têm sua geometria composta basicamente por elementos horizontais totalmente submersos (pontoons), pelo convés, e por elementos verticais que cruzam a superfície livre (colunas), estes últimos ligando os pontoons ao convés. Tal geometria é eficaz para manter reduzidas as oscilações sob a ação de ondas, mormente o heave, bem como para prover flutuação, área de convés e estabilidade estática compatíveis com a missão. Neste trabalho aplicam-se modelos bastante simplificados para representação de características geométricas e dos atributos acima mencionados. De fato, pontoons e colunas são representados por trechos de cilindros, enquanto que as oscilações sob ondas são determinadas a partir de formulação semelhante à Equação de Morison. Tais modelos compõem um processo de otimização para determinar dimensões principais e proporções que satisfaçam certos requisitos quanto ao peso, à área de convés, à estabilidade estática e ao heave. Resultados numéricos para as oscilações sob ondas são confrontados com dados experimentais obtidos para plataformas em escala reduzida ensaiadas no canal de ondas do Laboratório de Engenharia Naval e Oceânica da EPUSP, observando-se boa aproximação. O processo de otimização é aplicado a situações descritas na literatura, chegando-se a resultados compatíveis com aqueles publicados, com a vantagem da simplicidade dos modelos analítico-numéricos aqui adotados. / Semi-submersible platforms, which are used as floating structures for oil production and exploration in deep waters, have their geometry composed basically of totally submerged horizontal elements (pontoons), the deck, and vertical elements that cross the free surface, these latter linking the pontoons to the deck. This geometry is efficient for keeping the oscillations due to wave excitation at small levels, specially the heave, as well to provide floatation, deck area and static stability compatible to the platform?s mission. In the present work, rather simplified models are applied for the representation of the geometric characteristics and of the other above mentioned attributes. In fact, pontoons and columns are represented by cylinders, and oscillations due to waves are determined by a formulation similar to Morison?s equation. These models take part in an optimization process for the determination of the main dimensions and proportions that satisfy certain requirements concerning weight, deck area, static stability and the heave. Numerical results for the oscillations due to waves are compared to experimental data obtained for scaled platforms tested in the wave channel of the Naval and Oceanic Engineering Laboratory of EPUSP, leading to reasonable approximations. The optimization process is applied to some cases described in the Literature, leading to results compatible with the published ones, but with the advantage of the simplicity of the analytic-numerical models here adopted.
23

Síntese automática do leiaute usando o ASTRAN

Moura, Gisell Borges January 2017 (has links)
O trabalho usa a síntese do leiaute através do ASTRAN em circuitos que foram otimizados através da técnica de SCCG (Static CMOS Complex Gates) visando alcançar reduções em número de transistores. A metodologia apresentada permite a flexibilidade de utilizar células de quaisquer tamanho ou redes de transistores nos circuito otimizados. O trabalho compara estes circuitos otimizados pela método do ASTRAN e circuitos utilizando a metodologia standard cell. O fluxo de síntese é composto pelas etapas de otimização da netlist, verificação/extração e caracterização da células. O trabalho adaptou as tecnologias de fabricação CMOS de 600nm e 180nm para a ferramenta ASTRAN a partir das informações dos design kits das bibliotecas stantard cell XC06 e XC018 da XFAB. A síntese do leiaute das células complexas geradas é realizada pela ferramenta ASTRAN. Os experimentos foram realizados nas tecnologias de 180nm e 600nm para um conjunto de circuitos de bechmarks do ITC’99. As comparações foram realizadas entre a netlist otimizada e duas netlists geradas para cada biblioteca da XFAB. Uma netlist abrange todas as células da biblioteca e a outra tem uma restrição de células que são consideradas complexas (somadores, multiplexadores, XOR/XNOR, AOI e OAI). A netlist com restrições foi elaborada com a motivação de verificar se uma netlist com células complexas geradas exclusivamente para o circuito alvo se tornaria mais benéfico em termos de redução do número de transistores. Os resultados para 180nm apresentaram reduções nos melhores casos em número de transistores com até 15%, em potência dinâmica com até 24% e em potência de leakage com até 22%. Os resultados para 600nm apresentaram reduções nos melhores casos em número de transistores com até 17%, em área com até 14%, em potência dinâmica com até 22%, em potência de leakage com até 29%. Os experimentos mostraram que é possível alcançar reduções em número de transistores ao combinar o uso do ASTRAN com a técnica de otimização pelo uso de SCCG. / The work uses the synthesis of the layout through ASTRAN in circuits that have been optimized through the SCCG technique (Static CMOS Complex Gates) in order to achieve reductions in the number of transistors. The presented methodology allows the flexibility of using cells of any size or transistor networks in the optimized circuits. The work compares these circuits optimized by the ASTRAN method and circuits using the standard cell methodology. The synthesis flow is composed by the netlist optimization, verification / extraction and cell characterization steps. The work adapted 600nm and 180nm CMOS fabrication technologies for the ASTRAN tool from the design information of the XFAB standard cell XC06 and XC018 libraries. The synthesis of the complex cells generated is performed by the ASTRAN tool. The experiments were performed on the 180nm and 600nm technologies for a set of ITC'99 bechmarks circuits. Comparisons were made between the optimized netlist and two netlists generated for each XFAB library. A netlist covers all cells in the library and the other netlist has a restriction of cells that are considered complex (adders, multiplexers, XOR / XNOR, AOI, and OAI). The netlist with restrictions was designed with the motivation to check if a netlist with complex cells generated exclusively for the target circuit would become more beneficial in terms of reducing the number of transistors. The results for 180nm showed reductions in the best cases in the number of transistors with up to 15%, in dynamic power up to 24% and in leakage power with up to 22%. The results for 600nm showed reductions in the best cases in the number of transistors with up to 17%, in an area up to 14%, in dynamic power with up to 22%, in leakage power with up to 29%. The experiments showed that it is possible to achieve reductions in the number of transistors by combining the use of ASTRAN with the optimization technique using SCCG.
24

Aplicabilidade da modelagem otimizada no processo de diagramação de revista eletrônica e impressa no âmbito acadêmico

Amaral, Vinícius Rodrigues do 05 August 2016 (has links)
Submitted by Jailda Nascimento (jmnascimento@pucsp.br) on 2016-10-21T18:51:32Z No. of bitstreams: 1 Vinícius Rodrigues do Amaral.pdf: 12340469 bytes, checksum: eb42059c7a7f468161a246c5dddcc90e (MD5) / Made available in DSpace on 2016-10-21T18:51:32Z (GMT). No. of bitstreams: 1 Vinícius Rodrigues do Amaral.pdf: 12340469 bytes, checksum: eb42059c7a7f468161a246c5dddcc90e (MD5) Previous issue date: 2016-08-05 / The purpose of this study is to analyze the production of periodicals and identify the processes which may be substituted by an optimized modeling software to automate such processes totally or partially. Through a theoretical basis from the academic literature on the subject of optimized modeling, it was possible to carry out a mapping of several current periodicals present in SciElo and observe the occurrence of diagramming styles on this corpus, providing an empirical substantiation of recurring components in the layout of journals. The study follows with the critical analysis of the development of a matrix for receiving content of the articles and the analysis whether the objectives have been fulfilled in whole or in part / O propósito deste estudo é analisar a produção de periódicos e identificar os processos utilizados que podem ser substituídos por um software de modelagem otimizado que automatize totalmente ou parcialmente tais processos. Através de uma fundamentação teórica a partir da produção acadêmica na temática da modelagem otimizada, foi possível realizar um mapeamento de diversos periódicos atuais presentes na plataforma SciElo e observar a ocorrência de estilos de diagramação nesse corpus, propiciando uma fundamentação empírica dos componentes recorrentes na diagramação dos periódicos. O estudo segue com a análise crítica do desenvolvimento de uma matriz para recebimento de conteúdo dos artigos e a conclusão dos objetivos alcançados em sua totalidade ou parcialmente
25

Controle de frequência para otimização da potência em um sistema de transmissão de energia sem fios

Diniz Junior, Walter Ferreira January 2017 (has links)
Nesse trabalho é apresentada uma estratégia de controle para manter a potência entregue a carga do link indutivo de um sistema de transferência de potência sem fios maximizada continuamente. Inicialmente, foi desenvolvido o modelo do link indutivo do sistema, de forma a encontrar uma expressão para a potência na carga. Em seguida, essa expressão foi analisada, buscando os pontos de potência máxima correspondentes às frequências ressonantes quando o fator de acoplamento magnético do link indutivo era variado. Assim, foi estabelecido um método para estimar esse fator de acoplamento k e consequentemente da indutância mútua M a partir do monitoramento direto da fase e do módulo da corrente de entrada do link e indireto da impedância de entrada. Portanto, a estratégia de controle proposta consiste em monitorar a corrente da fonte de entrada do link para estimar o fator de acoplamento magnético k e finalmente, sintonizar a fonte na frequência de ressonância associada ao coeficiente de acoplamento magnético pela função obtida fres(k). Os resultados experimentais mostraram que a estratégia proposta aumenta significativamente a potência entregue a carga em comparação a uma fonte de alimentação sintonizada em uma frequência fixa. / A control strategy is presented in this work to maintain the power delivered to a load continuously maximized at the output of a wireless power transfer system. Initially, the inductive link model of the system was developed in order to find an expression for the power delivered to the load. Thus, the maximum power delivered to the load points were obtained experimentally while the magnetic coupling factor of the inductive link was varied and associated with the frequency of the source. The frequency and magnetic coupling variables were related to the maximum power on the load by a simple analytic function. Thus, a method has been established to estimate the coupling factor k and consequently the mutual inductance M by direct monitoring of the phase and the module of the input current of the link and indirect monitoring of the input impedance. Therefore, the proposed control strategy is to monitor the current of the input source of the link to estimate the magnetic coupling factor k and finally to tune the source at the resonance frequencies associated to the magnetic coupling coefficient by the obtained function fres(k). The experimental results showed that the proposed strategy increases significantly the power delivered to the load compared to a power source tuned at a fixed frequency.
26

People Matching for Transportation Planning Using Optimized Features and Texel Camera Data for Sequential Estimation

Wang, Ziang 01 May 2012 (has links)
This thesis explores pattern recognition in the dynamic setting of public transportation, such as a bus, as people enter and later exit from a doorway. Matching the entrance and exit of each individual provides accurate information about individual riders such as how long a person is on a bus and which stops the person uses. At a higher level, matching exits to entries provides information about the distribution of traffic flow across the whole transportation system. A texel camera is implemented and multiple measures of people are made where the depth and color data are generated. A large number of features are generated and the sequential floating forward selection (SFFS) algorithm is used for selecting the optimized features. Criterion functions using marginal accuracy and maximization of minimum normalized Mahalanobis distance are designed and compared. Because of the particular case of the bus environment, which is a sequential estimation problem, a trellis optimization algorithm is designed based on a sequence of measurements from the texel camera. Since the number of states in the trellis grows exponentially with the number of people currently on the bus, a beam search pruning technique is employed to manage the computational and memory load. Experimental results using real texel camera measurements show good results for 68 people exiting from an initially full bus in a randomized order. In a bus route simulation where a true traffic flow distribution is used to randomly draw entry and exit events for simulated riders, the proposed sequential estimation algorithm produces an estimated traffic flow distribution which provides an excellent match to the true distribution.
27

Optimisation of chlorine dosing for water disribution system using model-based predictive control

Muslim, Abrar January 2007 (has links)
An ideal drinking water distribution system (DWDS) must supply safe drinking water with free chlorine residual (FCR) in the form of HOCI and OCIֿ at a required concentration level. Meanwhile the FCR is consumed in the bulk liquid phase and at the DWDS pipes wall as the result of chemical reactions. Because of these, an optimized chlorine dosing for the DWDS using model-based predictive control (MBPC) is developed through the steps of modelling the FCR transport along the main pipes of the DWDS, designing chlorine dosing and implementing a multiple-input multiple-output system control scheme in Matlab 7.0.1 software. Discrete time-space models (DTSM) that can be used to predict free chlorine residual (FCR) concentration along the pipes of the DWDS over time is developed using explicit finite difference method (EFDM). Simulations of the DTSM using step and rectangular pulse input show that the effect of water flow rate velocity is much stronger than the effect of chlorine effective diffusivity coefficient on the FCR distribution and decay process in the DWDS main pipes. Therefore, the FCR axial diffusion in single pipes of the DWDS can be neglected. Investigating the effect of injection time, initial chlorine distribution, and overall chlorine decay rate constant involved in the process have provided a thorough understanding of chlorination and the effectiveness of all the parameters. This study proposed a model-based chlorine dosing design (MBCDD) based on a conventional-optimum design process (CODP) (Aurora, 2004), which is created for uncertain water demand based on the DTSM simulation. / In the MBCDD, the constraints must be met by designing distances between chlorine boosters and optimal value of the initial chlorine distribution in order to maintain the controlled variable (CV), i.e. FCR concentration with a certain degree of robustness to the variations of water flow rate. The MBCDD can cope with the simulated DWDS (SDWDS) with the conditions; the main pipe is 12 inch diameter size with the pipe length of 8.5 km, the first consumers taking the water from the point of 0.83 km, the assumed pipe wall chlorine decay rate constant of 0.45 m/day, and the value of chlorine overall decay rate constants follow Rosman's model (1994), by proposing a set of rules for selecting the locations for additional chlorine dosing boosters, and setting the optimal chlorine dosing concentrations for each booster in order to maintain a relatively even FCR distribution along the DWDS, which is robust against volumetric water supply velocity (VWS) variations. An example shows that by implementing this strategy, MBCDD can control the FCR along the 8.5 km main pipe of 12 inch diameter size with the VWS velocity from 0.2457 to 2.457 km/hr and with the assumed wall and bulk decay constants of 0.45 and 0.55 m/day, respectively. An adaptive chlorine dosing design (ACDD) as another CODP of chlorine dosing which has the same concept with the MBCDD without the rule of critical velocity is also proposed in this study. The ACDD objective is to obtain the optimum value of initial chlorine distribution for every single change in the VWS. Simulation of the ACDD on the SDWDS shows that the ACDD can maintain the FCR concentration within the required limit of 0.2-0.6 mg/1. / To enable water quality modelling for studying the effectiveness of chlorine dosing and injection in the form of mass flow rate of pure gaseous chlorine as manipulated variable (MV), a multiple-input multiple-output (MIMO) system is developed in Simulink for Matlab 7.0.1 software by considering the disturbances of temperature and circuiting flow. The MIMO system can be used to design booster locations and distribution along a main pipe of the DWDS, to monitor the FCR concentration at the point just before injection (mixing) and between two boosters, and to implement feedback and open-loop control. This study also proposed a decentralized model-based control (DMBC) based on the MBCDD-ACDD and centralized model predictive control (CMPC) in order to optimize MV to control the CV along the main pipe of the DWDS in the MIMO system from the FCR concentration at just after the chlorine injection (CVin) to the FCR concentration (CVo) before the next chlorine injection with the constraints of 0.2-0.6 ppm for both the CVin and CVo. A comparison of the performances of decentralized PI (DPI) control, DMBC and CMPC, shows that the performances of the DMBC and CMPC in controlling the MIMO system are almost the same, and they both are significantly better than the DPI control performance. In brief, model-based predictive control (MBPC), in this case a decentralized model-based control (DMBC) and a centralized predictive control (CMPC), enable optimization of chlorine dosing for the DWDS.
28

Adapting an FPGA-optimized  microprocessor to the MIPS32 instruction set / Anpassning av en FPGA-optimerad processor till  instruktionsuppsättningen MIPS32

Andersson, Olof, Bengtsson, Karl January 2010 (has links)
<p>Nowadays, FPGAs are large enough to host entire system-on-chip designs, wherein a soft core processor is often an integral part. High performance of the processor is always desirable, so there is an interest in finding faster solutions.This report aims to describe the work and results performed by Karl Bengtson and Olof Andersson at ISY. The task was to continue the development of a soft core microprocessor, originally created by Andreas Ehliar. The first step was to decide a more widely adopted instruction set for the processor. The choice fell upon the MIPS32 instruction set. The main work of the project has been focused on implementing support for MIPS32, allowing the processor to execute MIPS assembly language programs. The development has been done with speed optimization in mind. For every new function, the effects on the maximum frequency has been considered, and solutions not satisfying the speed requirements has been abandoned or revised.The performance has been measured by running a benchmark program—Coremark. Comparison has also been made to the main competitors among soft core processors. The results were positive, and reported a higher Coremark score than the other processors inthe study. The processor described herein still lacks many essential features. Nevertheless, the conclusion is that it may be possible to create a competitive alternative to established soft processors.</p> / <p>FPGAer används idag ofta för stora inbyggda system, i vilka en mjuk processor ofta spelar en viktig roll. Hög prestanda hos processorn är alltid önskvärt, så det finns ett intresse i att hitta snabbare lösningar. Denna rapport skall beskriva det arbete och de resultat som uppnåtts av Karl Bengtson och Olof Andersson på ISY. Uppgiften var att fortsätta utvecklandet av en mjuk processor, som ursprungligen skapats av Andreas Ehliar. Första steget var att välja ut en mer allmänt använd instruktionsuppsättning för processorn. Valet föll på instruktionsuppsättningsarkitekturen MIPS32. Projektets huvutarbete har varit fokuserat på att implementera stöd för MIPS32, vilket ger processorn möjlighet att köra assemblerprogram för MIPS.Utvecklingen har gjorts med hastighetsoptimering i beaktning. För varje ny funktion har dess effekter på maxfrekvensen undersökts,och lösningar som inte uppfyllt hastighetskraven har förkastats eller reviderats. Prestandan har mätts med programmet Coremark. Det har också gjorts jämförelser med huvudkonkurrenterna bland mjuka processorer. Resultaten var positiva, och rapporterade ett högre Coremarkpoäng än de andra processorerna i studien. Slutsatsen är att det ärmöjligt att skapa ett alternativ till de etablerade mjuka processorerna, men att denna processor fortfarande saknar väsentliga funktioner som behövs för att utgöra en mogen produkt.</p>
29

Theoretical and Computational Aspects of the Optimized Effective Potential Approach within Density Functional Theory

Heaton-Burgess, Tim January 2009 (has links)
<p>The computational success of density functional theory relies on the construction of suitable approximations to the exchange-correlation energy functional. Use of functional approximations depending explicitly upon the density alone appear unable to address all aspects of many-body interactions, such as the fundamental constraint that the ground state energy is a piecewise linear function of the total number of electrons, and the ability to model nonlocal effects. Functionals depending explicitly upon occupied and unoccupied Kohn–Sham orbitals are considered necessary to address these and other issues. This dissertation considers certain issues relevant to the successful implementation of explicitly orbital-dependent functionals through the optimized effective potential (OEP) approach, as well as extending the potential functional formalism that provides the formal basis for the OEP approach to systems in the presence of noncollinear magnetic fields.</p><p>The self-consistent implementation of orbital-dependent energy functionals is correctly done through the optimized effective potential approach—minimization of the ground state energy with respect to the Kohn–Sham potential that generates the set of orbitals employed in the energy evaluation. The focus on the potential can be problematic in finite basis set approaches as determining the exchange-correlation potential in this manner is an inverse problem which, depending upon the combination of orbital and potential basis sets employed, is often ill-posed. The ill-posed nature manifests itself as nonphysical exchange-correlation potentials and total energies. We address the problem of determining meaningful exchange-correlation potentials for arbitrary combinations of orbital and potential basis sets through an L-curve regularization approach based on biasing towards smooth potentials in the energy minimization. This approach generates physically reasonable potentials for any combination of basis sets as shown by comparisons with grid-based OEP calculations on atoms, and through direct comparison with DFT calculations employing functionals not depending on orbitals for which OEP can also be performed. This work ensures that the OEP methodology can be considered a viable many-body computational methodology.</p><p>A separate issue of our OEP implementation is that it can suffer from a lack of size-extensivity—the total energy of a system of infinitely separated monomers may not scale linearly with the total number of monomers depending upon how we construct the Kohn–Sham potential. Typically, a fixed reference potential is employed to aid in the convergence of a finite basis set expansion of the Kohn–Sham potential. This reference potential can be utilized to ensure other desirable properties of the resulting potential. In particular, it can enforce the correct asymptotic behavior. The Fermi–Amaldi potential is often used for this purpose but suffers from size-nonextensivity owing to the explicit dependence of the potential on the total number of electrons. This error is examined and shown to be rather small and rapidly approaches a limiting linear behavior. A size-extensive reference potential with the correct asymptotic behavior is suggested and examined.</p><p>We also consider a formal aspect of the potential-based approach that provides the underlying justification of the OEP methodology. The potential functional formalism of Yang, Ayers, and Wu is extended to include systems in the presence of noncollinear magnetic fields. In doing so, a solution to the nonuniqueness issue associated with mapping between potentials and wave functions in such systems is provided, and a computational implementation of the OEP in noncollinear systems is suggested.</p><p>Finally, as an example of an issue for which orbital-dependent functionals seem necessary to obtain a correct description, we consider the ground state structures of C<sub>4<italic>N</italic> + 2</sub> rings which are believed to exhibit a geometric transition from angle-alternation (<italic>N</italic> ≤ 2) to bond-alternation (<italic>N</italic> > 2). So far, no published DFT approach has been able to reproduce this behavior owing to the tendency of common density functional approximations to bias towards delocalized electron densities. Calculations are presented with the rCAM-B3LYP exchange-correlation functional that correctly predict the structural evolution of this system. This is rationalized in terms of the recently proposed delocalization error for which rCAM-B3LYP explicitly attempts to address.</p> / Dissertation
30

Landing Autopilot Design For An Uav

Hankoylu, Merve 01 February 2011 (has links) (PDF)
In this thesis, a landing autopilot for an UAV (IAI Pioneer RQ-2) is designed based on a nonlinear MATLAB model implemented with MATLAB/Simulink. In order to control the movement of the UAV at lateral and longitudinal axes, a speed, an altitude, a heading angle (direction) and a yaw rate controllers are designed. Controller design procedure is started with determination of different trim points of the aircraft. Next, the corresponding initial states and initial inputs are obtained. The model is linearized about those trim points and the gain values are determined. The resultant gain scheduled controller is used on the non-linear model. The response of the aircraft to these controllers is tested in a constrained landing area that is constructed with respect to applicable aviation regulations. The aircraft position is investigated whether it is inside or outside of this safe landing area. If it is inside, an optimized landing path set is obtained. The steepest descent method is used for multidimensional search and parabolic fit method is used for one dimensional search (as line search) in the optimization phase. In case it is outside the defined landing area a special algorithm which takes the aircraft into the desired region is applied. In addition, the area is allowed to move as much as possible depending on the situation with special regards to the length of the runway. Also a lateral position controller is designed in order to provide the reach of the aircraft to the main landing path.

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