Spelling suggestions: "subject:"panels"" "subject:"kanels""
311 |
Planejamento e controle da produção com a utilização de células de trabalho: estudo de caso em construções com vedações verticais em concreto armado moldadas in loco / Planning and control of production using work cells: a case study in constructions with cast-in-place concrete vertical panelsBezerra, Larissa Marinho Coelho de Medeiros 10 June 2010 (has links)
A indústria da construção civil vem assumindo um papel determinante no desenvolvimento econômico do país e vivenciado um crescimento exponencial que exige das empresas uma dedicação crescente na busca por novas tecnologias construtivas e ferramentas que auxiliem na gestão de empreendimentos. Sistemas construtivos racionalizados que repercutam na melhoria dos produtos com a redução de custos são essenciais para manter a competitividade no setor. O sistema construtivo de vedações verticais em concreto armado moldadas in loco confere uma alternativa na produção de habitações em larga escala caracterizada pela redução de custos e alta produtividade originando uma cadeia produtiva que auxilia no planejamento e controle da produção em obras. O presente trabalho tem como objetivo contribuir para o planejamento e o controle da produção de edificações que utilizam em seu processo o sistema construtivo anteriormente citado, propondo um modelo de organização da produção baseado na redução da variabilidade dos processos produtivos por meio do fluxo contínuo da produção, que proporcione o trabalho ininterrupto no canteiro de obras. A proposta associa os princípios que sustentam a filosofia produtiva da Lean Constrution, e recomenda um modelo para o planejamento operacional de curto prazo, que defina os fluxos produtivos pela aplicação de ritmos constantes nas atividades mediante o nivelamento dos recursos de mão-de-obra envolvidos no processo produtivo com a introdução de células produtivas que proporcionam lotes otimizados de trabalho, constituindo células de trabalho. / The construction industry has a decisive role in economic development of the country and experienced exponential growth requires dedication growing companies in the search for constructive new technologies and tools that will assist them in managing exposures. Constructive rationalized systems that reverberate in improvement of products with reducing costs is critical to remain competitive in the industry. The constructive system using cast-in-place concrete vertical panels confers an alternative in the production of large-scale housing characterized by reduced costs and high productivity that provides a productive chain which assists in the planning and production control in workplaces. This work aims to contribute to the planning and production control buildings that use its constructive system previously cited, proposing a model organization of production based on reducing variability in productive processes through streaming production, providing uninterrupted work on site. The proposal combines the principles supporting the production philosophy of Lean Constrution, and recommends a template for the short-term operational planning, defining workflows by applying patterns appearing in activities by the leveling of labour resources involved in the production process with the introduction of work cells that provide small batches of work.
|
312 |
[en] PHOTOVOLTAIC CONVERSION: COMPARISON AMONG PERFORMANCE MODELS / [pt] CONVERSÃO FOTOVOLTAICA: COMPARAÇÃO DE MODELOS DE DESEMPENHOLISBETH LUCIA MARTINEZ ORTEGA 02 May 2019 (has links)
[pt] O objetivo desta pesquisa de mestrado é comparar o desempenho de três modelos de simulação numérica (Duffie e Beckman, King et al. e Masters) sobre a capacidade de conversão fotovoltaica obtida em painéis, tomando o modelo de King et al. como base de referência já que este foi validado à luz de dados experimentais com grau de concordância (exatidão) entre 2,4 por cento a 5,4 por cento. As simulações fazem uso de dados oficiais (dados horários e dados médios mensais de radiação solar incidente, temperatura ambiente, velocidade de vento) disponibilizados pelo Instituto Nacional de Meteorologia do Brasil e de dados técnicos de desempenho do fabricante de painéis fotovoltaicos. A motivação para desenvolvimento do trabalho resulta da percepção da importância da energia solar
fotovoltaica como estratégia de sua inclusão e diversificação da matriz energética brasileira. A metodologia proposta consiste em: (i) comparar o desempenho dos três modelos estudados e (ii) aplicar a metodologia de cálculo para avaliar o desempenho na conversão fotovoltaica nas condições solarimétricas favoráveis de onze cidades brasileiras, assim criando uma escala que possa ser utilizada para estabelecer um benchmark nacional. Os resultados revelaram que o modelo Duffie e Beckman reproduz os resultados de conversão fotovoltaica obtido pelo modelo King et al. com grau de concordância 2,4 por cento, enquanto a concordância com o modelo Masters ultrapassa a faixa de exatidão (7,4 por cento). Como conclusão, o uso de dados meteorológicos médios mensais mostraram-se eficazes para estimar a energia elétrica que resulta do processo de conversão fotovoltaica em substituição aos dados horários nem sempre disponíveis. / [en] The goal of this MSc. dissertation is to compare the performance of three classical models of numerical simulation (Duffie and Beckman, King et al. and Masters) to generate electricity from the photovoltaic conversion obtained in panels, taking the model of King et al. as a baseline since it was validated vis-àvis experimental data within 2.4 percent to 5.4 percent. The simulations make use of official data (solar hourly and monthly data of solar incident radiation, temperature, wind speed) provided by the National Institute of Meteorology of Brazil and of performance data provided by the manufacturer of the photovoltaic panel. The motivation for development of the work resulted from the perception of the importance of photovoltaic energy as a strategy for diversification of the Brazilian energy matrix. The proposed methodology (i) compares the performance of the three models studied and (ii) applies it for assessing the performance of the photovoltaic conversion in eleven Brazilian cities that exhibit favourable conditions for photovoltaic conversion, thus creating a scale that can be used to establish a national benchmark. The results revealed that the Duffie and Beckman model reproduces the results of the photovoltaic conversion model obtained by King et al. degree within 2.4 percent, while the agreement with the model of Masters over range accuracy (7.4 percent). In conclusion, the use of monthly averaged meteorological data proved to be effective for estimating the energy that results from the process of photovoltaic conversion when hourly data is not available.
|
313 |
Uma interface de painel digital interativo para planejamento de projetos / A digital interactive panel interface for project planningCamila de Araujo 24 August 2012 (has links)
O uso de gestão visual, por meio de painéis físicos, é um diferencial do gerenciamento ágil de projetos. Os quadros servem de suporte para o trabalho colaborativo, permitindo que artefatos e indicadores sejam criados de maneira participativa e sejam divulgados de forma a motivar a comunicação, com uso de quadros brancos e recados autocolantes. Apesar dos argumentos sobre vantagens para a interação da equipe, há várias inconveniências nessa forma de armazenar as informações do projeto, como a perda de dados históricos. Por outro lado, vivencia-se a popularização de tecnologias que permitem a interação entre usuários, mediadas por painéis digitais touchscreen. Essa tecnologia pode substituir os painéis físicos com significativa ampliação de recursos. Este trabalho propõe uma interface original, de forma a combinar a simplicidade dos quadros físicos com as funcionalidades dos softwares de gerenciamento de projetos, segundo as diretrizes identificadas na teoria do gerenciamento de projetos, tanto na abordagem ágil como na tradicional e especialmente projetada para explorar recursos presentes em painéis digitais. Emprega-se uma revisão bibliográfica sistemática para demonstrar o estado da arte sobre softwares de gerenciamento de projetos e outra revisão bibliográfica para reunir as recomendações para projetos de interface em painéis digitais e interação usuário-computador, com a finalidade de construir a proposta. Em seguida, avalia a usabilidade dessa nova interface, comparando-a, por meio de experimentos, com o uso de softwares tradicionais de gerenciamento de projetos e softwares de gerenciamento ágil, voltados para o uso em desktop. Os resultados indicam que a nova interface gera uma maior satisfação para o usuário. A contribuição original está na interface apresentada, mostrando que há um espaço para o desenvolvimento de novos estudos na área de softwares de gerenciamento de projetos, englobando novas formas de interação e uso de novos dispositivos. / The use of physical boards with stickers to visual management is a differential of agile project management. This kind of artifact serves as a support for collaborative work allowing the creation of indicators in a participatory way in order to motivate the communication. There are several drawbacks in this way to store project information despite the arguments about advantages for team interaction with physical boards, such as the loss of historical data. On the other hand, the popularization of technologies that enable interaction between users, like digital touchscreen panels, grows. This technology can replace the physical boards with a significant expansion of resources. This paper proposes an original interface in order to combine the simplicity of the physical boards with the features of project management software tool, according to the guidelines identified in the theory of agile project management (PM) and traditional PM. It was specially designed to exploit resources present in digital panels. This research combines a systematic literature review to demonstrate the state of the art on project management software tool and a literature review to gather recommendations for interface design in digital dashboards and user-computer interaction in order to build the proposal. Then, the usability of this new interface was evaluates, comparing it with the traditional project management software tool and agile project management software tool, through experiment. The results indicate that the new interface generates greater satisfaction to the project management team. The original contribution is the interface presented showing that there is a space for the development of new studies in the area of project management software tool, embracing new forms of interaction and use of new devices.
|
314 |
Qualidade da Madeira Serrada e dos Pain?is Colados Lateralmente Obtidos de um Plantio de Eucalyptus saligna Smith Visando o Segmento Moveleiro / Quality of the Sawnwood and Glued Panels Obtained of a Eucalyptus saligna Smith Plantation for Furniture IndustryAmparado, Kelysson de Freitas 23 August 2008 (has links)
Made available in DSpace on 2016-04-28T14:56:18Z (GMT). No. of bitstreams: 1
2008 - Kelysson de Freitas Amparo.pdf: 3210670 bytes, checksum: fc139c4d95da126bd1c41d4980ceb74a (MD5)
Previous issue date: 2008-08-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this research were studied thirty trees of Eucalyptus saligna Smith wood, sampled in a
twenty year-old plantation located in Serop?dica/RJ. Each tree supplied a log with 2.30 meters
in length for the study of the sawn process and panels production ( PCLs ). The processing of
the logs was made in the LPZ Madeiras and Artefatos Ltda sawmill - Pira?/RJ, being
determined the revenue in sawnwood. Later on, the boards went by the process of artificial
drying, with controlled conditions, in the Laboratory of Wood Drying, of the Forest Products
Department, of the Forest Institute, of UFRuralRJ. In the qualitative evaluation, were
determinate the defects indexes of the wood after drying. Smaller pieces were produced and
were used in the glued panels production. The glued panels were produced from four
treatments, for comparison among them, being these: simple panel with simple top connection
(T1), simple panel with finger-joint connection (T2), double panel with simple top connection
(T3), and double panel with finger-joint connection (T4). Were quantified the revenue of the
conversion of the logs in sawnwood; the qualitative indexes of boards defects after the
artificial drying; the revenue of the conversion of the boards in glued panels (being eliminated
defects as cracks and severe torsion); and the resistance properties of PCLs through the shear,
traction and static bending tests, following normative procedures of the document ABNT
NBR 7190:1997 and ASTM D-1037. As practical example of the application of the
eucalyptus glued panels was produced an experimental furniture (armchair), being discussed
the problems and solutions found in the application of the studied material. / Neste trabalho foram avaliadas trinta ?rvores do g?nero Eucalyptus saligna Smith, amostradas
em um talh?o de vinte anos de idade localizado no campus da Universidade Federal Rural do
Rio de Janeiro, em Serop?dica/RJ. Cada ?rvore forneceu uma tora com 2,30 metros de
comprimento cada uma, para o estudo do processo em escala piloto de obten??o de madeira
serrada e pain?is colados lateralmente (PCLs). O processamento das toras foi efetuado na
serraria LPZ Madeiras e Artefatos Ltda., em Pira?/RJ, determinando-se o rendimento em
madeira serrada. Posteriormente, as t?buas passaram pelo processo de secagem artificial, em
c?mara de secagem automatizada com condi??es controladas, no Laborat?rio de Secagem, do
Departamento de Produtos Florestais, do Instituto de Florestas da UFRuralRJ. Na avalia??o
qualitativa, foram avaliados os ?ndices de defeitos na madeira ap?s secagem. A seguir as
t?buas foram levadas para o Laborat?rio de Usinagem e Beneficiamento da Madeira do
DPF/IF/UFRuralRJ, onde foram resserradas, produzindo sarrafos, que foram utilizados na
confec??o de pain?is colados lateralmente e de um m?vel (poltrona). Os pain?is colados
lateralmente foram produzidos a partir de quatro tratamentos, para compara??o entre eles,
sendo estes: painel simples com emendas de topo (T1), painel simples com emendas tipo
finger-joint (T2), painel com dupla camada de sarrafos com emendas de topo (T3), e painel
com dupla camada de sarrafos com emendas tipo finger-joint (T4). Foram quantificados o
rendimento da convers?o das toras em madeira serrada; os ?ndices qualitativos de defeitos
presentes nas t?buas ap?s a secagem artificial; o rendimento da convers?o da madeira serrada
em pain?is colados lateralmente (eliminando-se defeitos como rachaduras, n?s soltos e
empenamentos severos); e as propriedades de resist?ncia dos PCLs atrav?s dos ensaios de
cisalhamento e tra??o, adaptados ao material e seguindo procedimentos normativos do
documento ABNT NBR 7190:1997 e ensaios de flex?o orientados pelo documento normativo
ASTM D-1037 (norma americana). Como exemplo pr?tico da aplica??o dos pain?is colados
de eucalipto foi produzido um m?vel (poltrona), sendo discutidos e avaliados os problemas e
solu??es encontrados na aplica??o do material estudado.
|
315 |
Projeto de carga eletrônica para caracterização de painéis fotovoltaicos. / Design of an electronic load for photovoltaic module characterization.Hassem, Moreno Addad 19 May 2015 (has links)
A geração solar fotovoltaica em painéis de silício tem se destacado como uma maneira limpa e renovável de atender à demanda por energia elétrica. Este trabalho apresenta o projeto, construção e testes de um sistema autônomo para obtenção da curva IV e caracterização de painéis fotovoltaicos comerciais instalados em campo. Após um estudo do problema de medição de painéis solares, uma especificação da Solução foi concebida. Com base na especificação, foram realizados o projeto elétrico, a construção de protótipos, a escrita do software de medição e os testes de validação em laboratório. Para validação definitiva do hardware desenvolvido, foram realizados testes em campo utilizando um painel solar comercial. Após a tomada de dados e análise dos resultados, conclui-se que o dispositivo concebido atende aos requisitos especificados e cumpre sua proposta inicial. A metodologia empregada neste trabalho pode ser utilizada para geração de outros instrumentos com finalidade similar ou idêntica. / Photovoltaic solar generators, using silicon panels, have grown popular as a clean and renewable way to supply electrical energy. This work presents the project, construction and testing of an autonomous system for IV curve tracing and characterization of commercial photovoltaic panels deployed in the field. After a study how to properly measure solar panels, a Solution was put in a form of a specification. From specifications, the following phases took place: electrical project, prototype construction, software development and lab testing. To perform final validation of the developed hardware, a field test with a commercial solar panel was performed. After collecting and analyzing data from, it was concluded that the design fulfills the required specifications and intended goals. The methodology employed in this work and be utilized to generate other measuring instruments with similar or identical function.
|
316 |
Controle e gerenciamento de uma microrede com célula a combustível, painel fotovoltaico e armazenador de energia / Energy management and control of a microgrid using fuel cell, photovoltaic panel and energy storage deviceFuzato, Guilherme Henrique Favaro 15 July 2019 (has links)
O aprimoramento de técnicas e dispositivos aplicados à conversão de energia provenientes de fontes alternativas de energia, no contexto da geração distribuída, possui um papel importante para o estabelecimento definitivo de um novo paradigma de despacho e consumo de energia elétrica. Neste contexto, esta tese de doutorado aborda uma proposta de gerenciamento de energia e controle de uma microrede com célula a combustível e painel fotovoltaico como fontes primárias, operando juntamente com elementos armazenadores. Nesta proposta, destaca-se o uso de duas principais técnicas: droop k-sharing e Maximum Power Point Tracking with Saturation Technique (MPPT-ST). A técnica droop k-sharing permite associar uma dinâmica preestabelecida à célula a combustível, de forma que as baterias absorvam o espectro complementar. Adicionalmente, o uso da variável k-sharing com a adição da técnica droop permite o compartilhamento de potência entre as duas fontes sem a necessidade de comunicação entre elas. Já a técnica MPPT-ST, permite a operação de painéis fotovoltaicos no Maximum Power Point (MPP) e fora do MPP utilizando um saturador dinâmico. Por fim, propõe-se uma técnica para o acoplamento dos modelos dinâmicos dos conversores CC-CC por meio do equacionamento da tensão do barramento Corrente Contínua (CC) em espaços de estados, tornando possível analisar a estabilidade da microrede com o método indireto de Lyapunov. Para validar as técnicas propostas, são apresentados resultados de simulação e experimentais. / The improvement of techniques and devices applied to the energy conversion of alternative energy sources, in the distributed generation context, has an important role for the definitive establishment of the new paradigm of energy delivery and consumption. In this context, this PhD thesis addresses a proposal of an energy management strategy for microgrids with fuel cells and photovoltaic panels as primary sources, operating with storage devices. In the proposed control scheme, it is possible to highlight two control techniques: droop k-sharing and MPPT-ST. With the droop k-sharing technique, it is possible to design a specific dynamic behavior for the Fuel Cell, while the battery absorbs the complementary (high frequency) spectrum. Additionally, the use of the k-sharing variable with droop technique makes it possible to share the energy between the two sources without the need of a high-speed communication link. On the other hand, with the MPPT-ST technique, the photovoltaic modules can be operated in the MPP or off-MPP by using a simple dynamic anti-windup strategy. For the stability analysis using the Lyapunov Indirect Method, it is proposed a state space technique to couple the DC-DC converters models using the DC-link capacitor. Finally, to evaluate the proposed theoretical algorithm and analysis, simulations and experimental results are presented.
|
317 |
Matériaux hybrides organique-inorganique à base de résine et de particules d'oxydes : application dans les panneau photovoltaïques / Resin and oxide particles-based hybrid organic-inorganic materials and their application in photovoltaic panelsGirard, Anaëlle 06 June 2014 (has links)
Dans le contexte énergétique actuel, la conception de panneaux photovoltaïques efficaces représente une des solutions pour pallier à la pénurie prochaine des énergies fossiles. Cependant, les phénomènes de dégradation de l’encapsulant, un des matériaux passifs du panneau, sont une des origines de la baisse de rendement des modules. L’objectif de ce travail de thèse a été de concevoir, caractériser et évaluer les différentes propriétés de nouveaux encapsulants hybrides organique-inorganique contenant des ressources renouvelables. Ainsi, trois matériaux ont été élaborés à partir d’alcool polyvinylique (PVA), de résines terpéniques et de charges minérales (silice ou argile (Bentonite)). Un premier matériau comprenant PVA, résine et silicates, dans lequel composantes organique et inorganique sont liées par des liaisons covalentes fortes (hybride de classe II), a conduit à des stabilités thermiques et photochimiques, et des propriétés optiques et barrières à la vapeur d’eau et à l’oxygène, similaires à celles des encapsulants actuels.L’introduction de nanoparticules de silice dans un mélange PVA/résine via des liaisons faibles a ensuite fourni un matériau hybride de classe I aux propriétés barrières à la vapeur d’eau satisfaisantes mais avec des transparences optiques insuffisantes pour une utilisation comme encapsulant, du fait de l’agrégation des nanoparticules. Enfin, malgré une transparence optique devant être encore optimisée, un matériau hybride de classe I constitué de PVA, de résine et de Bentonite a conduit à de bonnes propriétés thermiques, photochimiques, barrières à la vapeur d’eau et surtout d’excellentes propriétés barrières à l’oxygène, ce qui ouvre de nouvelles perspectives (emballage alimentaire…). / In the current energetic context, the design of efficient solar photovoltaic panels represents one of the solutions to overcome the coming fossil fuels shortage. However, degradation phenomena of the encapsulant, one of the passive materials of the panel, have been evidenced as one of the reasons of the performance decrease. The aim of this PhD research work was to design, characterize and assess the different properties of more environment-friendly new hybrid organic-inorganic encapsulants. In this way, three materials have been developed using polyvinyl alcohol (PVA), terpenic resins and mineral fillers (silica or clay(Bentonite)). A first material including PVA, resin and silicates, in which both organic and inorganic networksare linked through strong covalent bonds (class II hybrid material), led to thermal and photochemical stabilities, and water vapor and oxygen barriers properties similar to those of commercial encapsulants.Dispersion of silica nanoparticles into PVA/terpenic resin mixture through weak bond then provided a class Ihybrid material showing rather good water vapor barrier properties but optical transmittance too low to beused as an encapsulant, due to the aggregation of the nanoparticles. Finally, despite an optical transparency that should be optimized, a class I hybrid material made of PVA, resin and Bentonite showed promisingbehavior with good thermal, photochemical and water barrier properties and remarkable oxygen barrier properties, which opens up new prospects in the field of food packaging.
|
318 |
EVALUATING LUBRICANTS IN SHEET METAL FORMINGLanzon, Joseph, kimg@deakin.edu.au 1999 July 1918 (has links)
The sheet metal forming process basically involves the shaping of sheet metal of various thickness and material properties into the desired contours. This metal forming process has been extensively used by the automotive industry to manufacture both car panels and parts. Over the years numerous investigations have been conducted on various aspects of the manufacturing process with varied success. In recent years the requirements on the sheet metal forming industry have headed towards improved stability in the forming process while lowering environmental burdens. Therefore the overall aim of this research was to identify a technique for developing lubricant formulations that are insensitive to the sheet metal forming process.
Due to the expense of running experiments on production presses and to improve time efficiency of the process the evaluation procedure was required to be performed in a laboratory. Preliminary investigations in the friction/lubricant system identified several laboratory tests capable of measuring lubricant performance and their interaction with process variables. However, little was found on the correlation between laboratory tests and production performance of lubricants. Therefore the focus of the research switched to identifying links between the performance of lubricants in a production environment and laboratory tests. To reduce the influence of external parameters all significant process variables were identified and included in the correlation study to ensure that lubricant formulations could be desensitised to all significant variables.
The significant process variables were found to be sensitive to die position, for
instance: contact pressure, blank coating of the strips and surface roughness of the dies were found significant for the flat areas of the die while no variables affected friction when polished drawbeads were used. The next phase was to identify the interaction between the significant variables and the main lubricant ingredient groups. Only the fatty material ingredient group (responsible for the formation of boundary lubricant regimes) was found to significantly influence friction with no interaction between the ingredient groups. The influence of varying this ingredient group was then investigated in a production part and compared to laboratory results.
The correlation between production performance and laboratory tests was found to be test dependant. With both the Flat Face Friction test and the Drawbead Simulator unaffected by changes in the lubricant formulation, while the Flat Bottom Cup test showing similar results as the production trial. It is believed that the lack of correlation between the friction tests and the production performance of the lubricant is due to the absence of bulk plastic deformation of the strip. For this reason the Ohio State University (OSU) friction test was incorporated in the lubricant evaluation procedure along with a Flat Bottom Cup test.
Finally, it is strongly believed that if the lubricant evaluation procedure highlighted in this research is followed then lubricant formulations can be developed confidently in the laboratory.
|
319 |
Demografisk sammansättning samt beteende hos medlemmar i panelJohansson, Henrik, Kardell, Mathias January 2010 (has links)
<p>The use of marketing research panels are a more and more frequently used source of information for studies within many different branches. The purpose of this report is to investigate the demographic composition of panels and compare it with the population of Sweden, a possible change in behaviour of respondents, and if the source of recruitment is the cause of possible differences in study results. The study was commissioned by Norstats Linkoping office. Sources for the data material include Norstat’s recruitment process and their two main panels with different recruitment sources. To enable a deeper investigation of behaviour we also constructed a survey that was sent to 2,714 members of Norstat’s internet panels.</p><p>The statistical analysis includes contingency table analysis, multiple logistic regression, and Poisson regression. The results show that the demographic composition does not fully cover all the aspects of the Swedish population and some groups are less represented than others. The behaviour tends to differ between panel members that have responded to three or less surveys compared to members that have responded to twenty or more surveys. Source of recruitment does not seem to affect the results of studies, but it has some effect on the demographic composition of marketing research panels.</p> / <p>Användandet av paneler som källa vid undersökningar har den senaste tiden blivit en allt vanligare företeelse. Denna rapport har för avsikt att undersöka panelers demografiska sammansättning och överensstämmande med Sveriges befolkning, eventuell ändring av svarsbeteende samt huruvida rekryteringskällan ger upphov till kvalitetsskillnader hos medlemmar i en panel. Företaget Norstat har med sitt kontor i Linköping figurerat som uppdragsgivare till arbetet. Datamaterialet till studien har uppkommit från Norstats rekryteringsprocess samt från företagets två huvudpaneler med olika rekryteringskällor. För att djupare undersöka svarsbeteende konstruerade vi även en enkätundersökning som skickades ut till 2 714 medlemmar i Norstats internetpaneler.</p><p>Den statiska analysen innefattar χ2-test, multipel logistisk regression samt Poissonregression. Resultaten påvisade att den demografiska sammansättningen i panelen inte fullt ut speglade Sveriges befolkning samt att vissa grupper undertäcks i högre utsträckning än andra. Svarsbeteendet hos medlemmar i paneler har en tendens att ändras från det att medlemmen har svarat på en till tre undersökningar, till det att den har svarat på tjugo undersökningar eller fler. Rekryteringskällan till en panel verkar inte ge upphov till några större skillnader i svarsresultat, men däremot finns vissa skillnader i demografisk sammansättning.</p>
|
320 |
Digital Control Of Solar Photovoltaic ConvertersSrinath, R 12 1900 (has links)
A photo-voltaic system consists of solar cells, power converters, battery and the load. The power converter interfaces the solar cells, battery and the load. The battery serves to equalise the energy demand (load) and the energy supply (solar cell). Currently the solar cells and the battery cost nearly 90% of the system cost.
A typical photo-voltaic system can adopt various power bus configurations. Battery tied bus is the simplest of the power bus configurations. In this topology, the battery is always attached to the bus. This system is extremely simple in terms of power circuit configuration as well as control. Such systems weigh less and are more reliable. However, the battery tied bus suffers certain disadvantages. The first among them is the poor utilisation of solar panels. The load has to tolerate the full swing of the battery voltage variation. On account of the constraint on the solar panel voltage, the solar panels may not be loaded to the maximum power capacity. Such operating conditions lead to gross under-utilisation of the expensive solar panels. The battery tied bus configuration is designed, built and evaluated experimentally with 4 solar panels rated at 35 W each and a lead acid battery of 12 V 42 AH rating. This thesis explores alternate power architecture to overcome the above limitations. Load regulation and maximum power harvesting from the solar panels are the objectives.
In the proposed configuration, a bidirectional power converter is inserted between the bus and the battery. The bidirectional power converter operates in boost mode and charges the battery when the sunlight is available. During eclipse period, it operates in buck mode and meets the load demand. The maximum power is extracted from the panels by controlling the voltage across the solar panels. The bus voltage reference is computed by MPPT block and the bus voltage is regulated to the reference voltage through closed loop control. So the maximum power is extracted from the panels at the expense of extra bidirectional power converter. Even though there is an additional power loss due to the introduction of power converter, this power bus configuration is superior because it increases the output power from the panel itself. The entire control logic implementation is done digitally using dspic30F6010A. The simulation is done by writing script files in C language. The proposed bus configuration is designed, built and evaluated experimentally with the same setup and the results are then compared.
|
Page generated in 0.0293 seconds