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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.
111

Control for transient response of turbocharged engines

Cieslar, Dariusz January 2013 (has links)
The concepts of engine downsizing and down-speeding offer reductions in CO2 emissions from passenger cars. These reductions are achieved by reducing pumping and friction losses at part-load operation. Conventionally, rated torque and power for downsized units are recovered by means of turbocharging. The transient response of such engines is, however, affected by the static and dynamic characteristics of the turbo-machinery. Recent advances in engine simulation and control tools have been employed for the purpose of the research reported in this thesis to identify and verify possible air-path enhancements. A systematic method for evaluating various turbocharger assistance concepts is proposed and discussed in this thesis. To ensure a fair comparison of selected candidate systems, an easily reconfigurable controller providing a close-to-optimal operation, while satisfying physical limits, is formulated. This controller is based on the Model Predictive Control framework and uses a linearised mean value model to optimise the predicted behaviour of the engine. Initially, the controller was applied to a 1D simulation model of a conventional light-duty Diesel engine, for which the desired closed-loop features were verified. This procedure was subsequently applied to various air-path enhancement systems. In this thesis, a turbocharger electric assistance and various concepts based on compressed gas injection were considered. The capability of these systems to improve engine response during third gear tip-in manoeuvre was quantified. This investigation was also complemented with a parametric study of how effectively each of the considered methods used its available resources. As a result, injecting compressed gas into the exhaust manifold was identified as an effective method, which to date has attracted limited attention from engine research community. The effectiveness of the exhaust manifold assistance was experimentally verified on a light-duty Diesel engine. The sensitivity of the improvements to compressed gas supply parameters was also investigated. This led to the development of the BREES system: a low component count, compressed gas based system for reducing turbo-lag. It was shown that during braking manoeuvres a tank can be charged to the level sufficient for a subsequent boost assistance event. Such a functionality was implemented with a very limited set of additional components and only minor changes to the standard engine control.
112

Agentbaserade beslutsstöds framtida roll i strategisk stadsplanering.

Hallberg, Ida January 2022 (has links)
In community planning, accessibility is a recurring concept. The concept has also time and time again proved to have a great impact on how well an area develops. Its important role in community planning has resulted in a large amount of research in the field. The meaning and definition of the term varies markedly depending on the context and there are several different methods and tools for measuring accessibility. This creates a problem for decision makers to be able to take the planning options that will generate the greatest availability. Agent-based decision support systems are a decision support system that is currently receiving a great deal of attention in the literature. Real systems of interest are implemented in a simulation program to be able to support decision-making. The purpose of the study is to examine the decision materials for community planning that are used to increase different perspectives on accessibility and how agent-based modeling could be used. In the study, a categorization has been developed based on different models to measure accessibility based on existing literature. The study is based on a deductive approach and builds on existing literature. Through interviews with regions, municipalities and the Swedish Transport Administration, the current situation for the decision basis for community planning that is used to increase different perspectives on accessibility has been mapped. The interviews and categorization will also look at the future role of agent-based modeling as decision support in planning different perspectives on accessibility. The study shows that there is a need for clearer routines linked to the work with accessibility and an increased use of GIS, this could be obtained from an ABDS tool. Several advantages of ABDS systems have been identified, such as clarifying the concept of accessibility and how it is affected by different alternatives. There are also several future challenges for the use of the system, such as the problem that selected algorithms have a major impact on the results. / I samhällsplanering är tillgänglighet ett återkommande begrepp. Begreppet har även gång på gång visat sig ha en stor påverkan för hur väl ett område utvecklas. Dess viktiga roll i samhällsplaneringen har resulterat i en stor mängd forskning inom området. Begreppets innebörd och definition varierar markant beroende på sammanhang och det finns flertal olika metoder och verktyg för att mäta tillgänglighet. Detta skapar en problematik för beslutsfattare att kunna ta de planeringsalternativ som kommer att generera den största tillgängligheten. Agentbaserade beslutsstödsystem (ABDS) är ett beslutsstödsystem som för närvarande uppmärksammas väldigt mycket i litteraturen. Verkliga system av intresse implementeras i ett simuleringsprogram för att kunna stödja beslutsfattande. Syftet med studien är att undersöka beslutsunderlagen för samhällsplanering som används för att öka olika perspektiv på tillgänglighet samt hur agentbaserad modellering skulle kunna nyttjas. I studien har en formell värderingsmodell tagits fram utifrån olika perspektiv på tillgänglighet baserat på existerande litteratur. Studien baseras på en deduktiv ansats och bygger vidare från existerande litteratur. Genom intervjuer med regioner, kommuner och Trafikverket har nuläget för beslutsunderlagen för samhällsplanering som används för att öka olika perspektiv på tillgänglighet kartlagts. Intervjuerna och värderingsmodellen kommer även se till den framtida roll som agentbaserad modellerings som beslutsstöd har vid planering av olika perspektiv på tillgänglighet. Studien visar på att det finns ett behov för tydligare rutiner kopplade till arbetet med tillgänglighet samt en ökad användning av GIS, detta skulle kunna erhållas av ett ABDS-verktyg. Det har identifierats flertal fördelar med ABDS-system såsom att tydliggöra begreppet tillgänglighet och hur den påverkas av olika alternativ. Det finns även flertal framtida utmaningar för användning av systemet som t.ex. problemet att utvalda algoritmer har en stor inverkan på resultaten.
113

Prozessintegrierte Dokumentation und optimierte Wiederverwendung von Simulationsmodellen der automobilen Funktionsabsicherung

Gruber, Thomas 26 September 2016 (has links)
Die Schaffung, Wahrung und Nutzung von Wissen stellt heute eine wichtige Säule für die Konkurrenzfähigkeit von Unternehmen am Markt dar. Vor diesem Hintergrund steht insbesondere die moderne Funktionsentwicklung der Automobilindustrie vor der Herausforderung immer neue, hochgradig vernetzte Fahrzeugfunktionen zu entwickeln und in immer kürzerer Zeit und immer geringeren Kosten in den Markt zu bringen. Um dieser Herausforderung gerecht zu werden, hat sich die modellbasierte Entwicklung mit dem Ziel der Beherrschung dieser steigenden Komplexität etabliert. Dadurch ist es möglich die Entwicklungsaufgaben auf unterschiedlichen Ebenen zu abstrahieren und eine verteilte, vernetzte Entwicklung zu realisieren. Die Entwicklung einer einzigen Funktion benötigt heute häufig mehrere hundert Personen, die in einen gemeinsamen Entwicklungsprozess integriert werden müssen. Hier fehlt es an Konzepten um den Informations- und Wissensfluss zwischen den Prozessbeteiligten sicherzustellen. In diesem Kontext entwickelt die vorliegende Arbeit einen Ansatz zur prozessintegrierten Dokumentation der in modellbasierten Entwicklungsprozessen benötigten Entwicklungsartefakte. Der Ansatz betrachtet dabei den vollständigen Informationsfluss, von der Definition benötigter Informationen, über deren automatisierte Erfassung und Verarbeitung bis zur zielgerichteten Wiederverwendung. Anschließend skizziert die Arbeit die Architektur eines Informationssystems, dass diese Durchgängigkeit in beliebigen, modellbasierten Entwicklungsprozessen ermöglicht und überträgt diese zur Validierung des Ansatzes auf einen konkreten Entwicklungsprozess der automobilen Funktionsentwicklung. Der Fokus des Ansatzes liegt dabei insbesondere auf der Integration in bestehende Entwicklungsprozesse, ohne in diese verändernd einzugreifen. Dies wird einerseits durch eine modellbasierte Beschreibung des Informationsmodells, mit Methoden wie sie im Funktionsentwicklungsprozess Anwendung finden, erreicht. Prozessbeteiligte können dadurch das Informationsmodell selbst verstehen und bei Bedarf Anpassungen vornehmen, ohne auf geschulte Experten angewiesen zu sein. Andererseits erlaubt der architektonische Ansatz einen direkten Zugriff auf bestehende Entwicklungssysteme und darin enthaltenen dokumentationsrelevanten Informationen. / Today, the creation, preservation and exploitation of knowledge represent key factors of the competitiveness of companies in the global market. In this context, the modern function development in the automotive industry faces challenges to bring new, highly interconnected vehicle functions at shorter time and lower cost to the market. To meet these challenges and manage the growing compelity, a model-based development process has been established. Thus, it is possible to distribute development tasks to different levels of abstraction and enable a distributed, interconnected function development.This development involves up to several hundred persons per function, who have to be integrated in a common development process. Especially when it comes to managing the information and knowledge flow between the process participants, there is a lack of concepts to support this communication. Based on this context, this work presents an approach for process integrated documentation of the necessary development artifacts in model-based development processes. This approach considers the complete information flow, from the definition of necessary information, over automatic acquisition and processing to its targeted reuse during the process. Subsequently, this work sketches the architecture of an information system, which enables this continuous approach to be applied to any model-based development process. For validation purposes, the approach is then applied to an actual development process of the automotive function development. The focus of the presented approach lies in the integration in existing development processes without changing them. On the one hand, this is achieved by applying a model-based description of the information model using methods, that can be found in the function development process today. Thus, process participants can understand the information model themselves and apply changes when they are required without the necessity of qualified experts. On the other hand, the architectural approach allows a direct access to existing development systems and documentation relevant information they contain.
114

Simulační model řízení obchodní jednotky / Simulation model of a retail store

BRYCHCÍN, Karel January 2013 (has links)
In this work are summarized the theoretical basis of retail and simulation models usable as decision making support in the management of retail units. There are described the specifics of retail and specifics of retail units in terms of their classification and basic theoretical foundations for the creation of simulation models. The work also describes the default multi-agent simulation model created by the leader of this work,. Ing. Viktor Vojtko, Ph.D., on which this work builds. Then work describes creation of case studies using multi-agent simulation model, including the calibration process of models for these case studies. General methodology of creating case studies is described in next part of the work. Then the created methodology is varified by scenarios and the last part describes proposals for further editing of simulation model.
115

Maîtrise du procédé hybride de projection thermique avec refusion laser in-situ : approches numérique et expérimentale / Investigation of hybrid plasma spraying process with in situ laser remelting : numerical and experimental methods

Liu, Jiangwei 20 January 2016 (has links)
La projection hybride combinant la projection plasma et la refusion laser est une solution alternative permettant de diminuer ou même d'éliminer la présence de pores et de fissures au sein d'un dépôt brut de projection. Lors d'un procédé de projection plasma ou de refusion laser, le système substrat/dépôt subissant l'élévation de température,la fusion, la solidification et le refroidissement rapide est ainsi soumis à des gradients de température élevés, un niveau de contraintes élevé, et même un risque de formation de fissures. Il est alors important de pouvoir maîtriserles variations de température et la distribution des contraintes résiduelles au sein même du système. Concernantles travaux effectués dans cette thèse, des modèles thermiques et mécaniques ont été développés à l'aide dulogiciel ANSYS, de sorte à améliorer notre compréhension des comportements thermique et mécanique des revêtements élaborés par projection plasma avec refusion laser.Tout d'abord, la simulation du procédé de projection plasma a été développée afin de prédire les champs transitoires de température, la déformation finale de l'échantillon et les contraintes résiduelles dans des dépôts céramiques (alumine) et métalliques (NiCrBSi). Les contraintes résiduelles résultent de l'équilibre entre contraintes de trempe (toujours en tension) et contraintes thermiques lors du refroidissement final (en compression ou en tension suivant le cas). En raison de la faible limite d'élasticité du dépôt, les contraintes thermiques dominent les contraintes résiduelles dans le cas du dépôt d'alumine. En revanche, les contraintes de trempe dans le dépôt de NiCrBSi sont plus importantes. Par ailleurs, l'augmentation de l'efficacité du système de refroidissement mis en oeuvre permet de diminuer le niveau des contraintes résiduelles dans le dépôt d'alumine. Inversement les contraintes résiduelles au sein du dépôt de NiCrBSi augmentent lorsque le refroidissement en cours de projection est accru. L'analyse thermique permettant de simuler le procédé de refusion laser à posteriori d'un revêtement de NiCrBSi a été effectuée de sorte à évaluer les effets des paramètres du laser sur le champ de température engendré et laforme du bain refondu. Un coefficient d'absorption de 0.5 a été estimé par comparaison de l'épaisseur du bain refondu obtenue par les méthodes numérique et expérimentale. De plus, les morphologies de revêtements refondus ont été caractérisées par méthodes expérimentales. Selon l'analyse mécanique de la refusion laser à posteriori, les contraintes résiduelles sont en tension dans le dépôt refondu, mais en compression vers la zone non-refondue.Concernant le modèle portant sur l'élaboration de couches multiples, permettant de simuler le procédé de refusion laser in-situ, une diminution des contraintes transitoires au sein des couches préalablement élaborées est induite par l'accumulation progressive de chaleur au cours du processus d'élaboration. Après refroidissement final, les contraintes résiduelles suivant la direction de déplacement présentent une amplitude plus importante que suivant les autres directions. De plus, des solutions permettant de diminuer le niveau des contraintes dans le dépôt après refusion ont été recherchées, en faisant notamment varier l'efficacité du système de refroidissement ou le préchauffage du substrat. Il s'avère que l'amplitude des contraintes résiduelles dans le dépôt après refusion est plus sensible à la variation du préchauffage du substrat qu'à la modification de l'efficacité du système de refroidissement. / The hybrid spraying process consisting in plasma spraying and laser remelting is an alternative method to minimize or even eliminate the potential defects within the as-sprayed coatings.During the treatment of plasma spraying or laser remelting, the substrate/coating system undergoing heating, melting, solidification and fast cooling processes is submitted to high temperature gradients, high stress levels and even risks of crack formation. It is therefore important to control the temperature variation and stress level within the substrate/coating system. In this study, thermal and mechanical models established with ANSYS were developed to provide a fundamental understanding of thermal and mechanical behaviors of deposited coatings during plasma spraying and laser remelting processes.3D simulation models were first developed to predict the temperature field, the final deformation of the specimen, and the residual stresses within ceramic (alumina) and metallic (NiCrBSi) coatings. The final residual stresses result from the balance between quenching stresses (tensile) and thermal stresses (compressive or tensile). Due to the low value of the yield stress, the thermal stresses (compressive for that case) dominate the final stress level in the case of the ceramic coating (alumina). On the contrary, the final residual stresses within the NiCrBSi coating are tensile. It is also predicted that an increase of the cooling efficiency induces a lower stress level for the alumina coating, while improving the cooling efficiency slightly increases the residual stresses for the case of the metallic coating (NiCrBSi).Thermal analysis to predict laser post-remelting of a NiCrBSi coating was then carried out to investigate the effects of the laser parameters on the temperature field as well as on the remelted pool shape. An absorption coefficient of 0.5 was estimated by comparison of the remelted pool depths obtained by experimental and numerical methods. In addition, the morphologies of theremelted coating were characterized by experimental methods. According to the mechanical analysis for laser post-remelting of NiCrBSi coatings, the predicted residual stresses were tensile within the remelted coating, whereas those within the non- emelted zone were reversed from tensile before remelting to compressive after laser post-remelting. According to the numerical analysis of in situ laser remelting by a multi-layer model, transient stresses in the former deposited layers were decreased progressively due to the heat accumulation during the following deposition process. For the residual stresses after final cooling, the stress component along the displacement direction presents a higher level in comparison with the transverse andthrough thickness components. Solutions allowing decreasing the stress level within the remelted coating were studied by changing the cooling efficiency and the initial temperature of the substrate. It was noted that the generated residual stress (tensile) was more sensitive to the initial temperature of the substrate, than to the efficiency of the cooling system. In particular, increasing the initial temperature of the substrate could significantly decrease the stress magnitude within the remelted coating, and even reverse the residual stresses within the nonremelted part of the coating to compressive values.
116

Developing a methodology to account for commercial motor vehicles using microscopic traffic simulation models

Schultz, Grant George 30 September 2004 (has links)
The collection and interpretation of data is a critical component of traffic and transportation engineering used to establish baseline performance measures and to forecast future conditions. One important source of traffic data is commercial motor vehicle (CMV) weight and classification data used as input to critical tasks in transportation design, operations, and planning. The evolution of Intelligent Transportation System (ITS) technologies has been providing transportation engineers and planners with an increased availability of CMV data. The primary sources of these data are automatic vehicle classification (AVC) and weigh-in-motion (WIM). Microscopic traffic simulation models have been used extensively to model the dynamic and stochastic nature of transportation systems including vehicle composition. One aspect of effective microscopic traffic simulation models that has received increased attention in recent years is the calibration of these models, which has traditionally been concerned with identifying the "best" parameter set from a range of acceptable values. Recent research has begun the process of automating the calibration process in an effort to accurately reflect the components of the transportation system being analyzed. The objective of this research is to develop a methodology in which the effects of CMVs can be included in the calibration of microscopic traffic simulation models. The research examines the ITS data available on weight and operating characteristics of CMVs and incorporates this data in the calibration of microscopic traffic simulation models. The research develops a methodology to model CMVs using microscopic traffic simulation models and then utilizes the output of these models to generate the data necessary to quantify the impacts of CMVs on infrastructure, travel time, and emissions. The research uses advanced statistical tools including principal component analysis (PCA) and recursive partitioning to identify relationships between data collection sites (i.e., WIM, AVC) such that the data collected at WIM sites can be utilized to estimate weight and length distributions at AVC sites. The research also examines methodologies to include the distribution or measures of central tendency and dispersion (i.e., mean, variance) into the calibration process. The approach is applied using the CORSIM model and calibrated utilizing an automated genetic algorithm methodology.
117

Stochastic Simulation Of Daily Rainfall Data Using Matched Block Bootstrap

Santhosh, D 06 1900 (has links)
Characterizing the uncertainty in rainfall using stochastic models has been a challenging area of research in the field of operational hydrology for about half a century. Simulated sequences drawn from such models find use in a variety of hydrological applications. Traditionally, parametric models are used for simulating rainfall. But the parametric models are not parsimonious and have uncertainties associated with identification of model form, normalizing transformation, and parameter estimation. None of the models in vogue have gained universal acceptability among practising engineers. This may either be due to lack of confidence in the existing models, or the inability to adopt models proposed in literature because of their complexity or both. In the present study, a new nonparametric Matched Block Bootstrap (MABB) model is proposed for stochastic simulation of rainfall at daily time scale. It is based on conditional matching of blocks formed from the historical rainfall data using a set of predictors (conditioning variables) proposed for matching the blocks. The efficiency of the developed model is demonstrated through application to rainfall data from India, Australia, and USA. The performance of MABB is compared with two non-parametric rainfall simulation models, k-NN and ROG-RAG, for a site in Melbourne, Australia. The results showed that MABB model is a feasible alternative to ROG-RAG and k-NN models for simulating daily rainfall sequences for hydrologic applications. Further it is found that MABB and ROG-RAG models outperform k-NN model. The proposed MABB model preserved the summary statistics of rainfall and fraction of wet days at daily, monthly, seasonal and annual scales. It could also provide reasonable performance in simulating spell statistics. The MABB is parsimonious and requires less computational effort than ROG-RAG model. It reproduces probability density function (marginal distribution) fairly well due to its data driven nature. Results obtained for sites in India and U.S.A. show that the model is robust and promising.
118

Developing a methodology to account for commercial motor vehicles using microscopic traffic simulation models

Schultz, Grant George 30 September 2004 (has links)
The collection and interpretation of data is a critical component of traffic and transportation engineering used to establish baseline performance measures and to forecast future conditions. One important source of traffic data is commercial motor vehicle (CMV) weight and classification data used as input to critical tasks in transportation design, operations, and planning. The evolution of Intelligent Transportation System (ITS) technologies has been providing transportation engineers and planners with an increased availability of CMV data. The primary sources of these data are automatic vehicle classification (AVC) and weigh-in-motion (WIM). Microscopic traffic simulation models have been used extensively to model the dynamic and stochastic nature of transportation systems including vehicle composition. One aspect of effective microscopic traffic simulation models that has received increased attention in recent years is the calibration of these models, which has traditionally been concerned with identifying the "best" parameter set from a range of acceptable values. Recent research has begun the process of automating the calibration process in an effort to accurately reflect the components of the transportation system being analyzed. The objective of this research is to develop a methodology in which the effects of CMVs can be included in the calibration of microscopic traffic simulation models. The research examines the ITS data available on weight and operating characteristics of CMVs and incorporates this data in the calibration of microscopic traffic simulation models. The research develops a methodology to model CMVs using microscopic traffic simulation models and then utilizes the output of these models to generate the data necessary to quantify the impacts of CMVs on infrastructure, travel time, and emissions. The research uses advanced statistical tools including principal component analysis (PCA) and recursive partitioning to identify relationships between data collection sites (i.e., WIM, AVC) such that the data collected at WIM sites can be utilized to estimate weight and length distributions at AVC sites. The research also examines methodologies to include the distribution or measures of central tendency and dispersion (i.e., mean, variance) into the calibration process. The approach is applied using the CORSIM model and calibrated utilizing an automated genetic algorithm methodology.
119

SIMULAÇÃO DINÂMICA DA SOJA, MILHO E FEIJÃO, CULTIVADO SOB DIFERENTES REGIMES HÍDRICOS / DYNAMIC SIMULATION OF SOYBEANS, CORN AND BEAN, GROWN UNDER DIFFERENT WATER REGIMES

Vivan, Gisele Aparecida 15 January 2014 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Agribusiness has high importance in the state of Rio Grande do Sul, with the incorporation of fundamental importance to maintain its competitiveness and attractiveness factor technologies. Irrigation has become among the leading technologies available, featuring as main advantages to increase productivity and reduce risks associated with droughts. The determination of productive crop responses via simulation models has elevated in recent years, combining the agricultural sector the possibility of predictions about various scenarios, among these, water availability, reducing time and costs. In the same way, performing historical analyzes of production and profitability are essential for decision making related to incorporeal technologies in agricultural practice. This study aims to determine, via simulation models, productive responses of soybean, maize and beans, grown under different water regimes by performing temporal and risk analysis of the results obtained for the region of Santiago, RS. The study was conducted in the municipality of Santiago (29° 09 'S and 54 ° 51 ' O), with crops of soybeans, corn and beans, calibration and validation of models for these cultures in the DSSat system being performed, and subsequent evaluation and compared to the available models for soybean and beans in RSAP system. In the models considered fit after evaluation, sequences of climatic data (1961-2010) and certain productive responses related to growing conditions in rainfed and under great water conditions being held temporal and annual profitability analysis were included. The Cropgro - Soybean, Ceres-Maize - and Cropgro Drybean, framed models obtained performance as very good, very good and good for simulation of the production of grain (PG) of soybean, corn and beans, respectively, and great for simulation maximum production of dry matter (MSM) for all cultures. In comparison to the productive field responses versus models available in the DSSat system and RSAP, it was observed that for soybean and bean, the simulations obtained with the DSSat minor variations for soybeans, and RSAP for beans, however, both systems showed variations considered satisfactory. For historical simulations, the upland, the three studied crops (soybean, maize and beans), showed significant reductions in production and consequent income due to the drought. In both conditions of crops (dryland and irrigated) the higher costs, income and income were associated with maize, followed by soy beans. Comparing irrigated with dryland, the bean crop showed the greatest increases in profit complementation function of water, followed by corn and soybeans. Conclude that the simulation models were presented as useful tools for determining the yield response of crops under study, and compared with rainfed crops irrigated, the last were more interesting technically and economically. / O agronegócio apresenta elevada importância no Estado do Rio Grande do Sul, sendo a incorporação de tecnologias fator fundamental para manter a sua competitividade e atratividade. A irrigação apresenta-se dentre as principais tecnologias disponíveis, apresentando como principais vantagens a elevação da produtividade e a redução de riscos associados as estiagens. A determinação das respostas produtivas das culturas via modelos de simulação tem elevado-se nos últimos anos, aliando ao setor agropecuário a possibilidade de previsões sobre diversos cenários, dentre estes, os de disponibilidade hídrica, com redução de tempo e custos. Neste mesmo sentido, a realização de análises históricas de produções e rentabilidades são essenciais para tomadas de decisão relacionadas a incorpação de tecnologias na prática agrícola. O presente trabalho tem como objetivo determinar, via modelos de simulação, as respostas produtivas das culturas da soja, milho e feijão, cultivadas sob diferentes regimes hídricos, realizando análise temporal e de risco dos resultados obtidos, para a região de Santiago, RS. O trabalho foi realizado para o município de Santiago (29°09 S e 54º51 O), com as culturas da soja, milho e feijão, sendo realizada a calibração e validação dos modelos relativos a estas culturas presentes no sistema DSSat; e posterior avaliação e comparação com os modelos disponíveis para as culturas da soja e feijão no sistema RSAP. Nos modelos considerados aptos após a avaliação, foram inseridas sequencias de dados climáticos (1961-2010) e determinadas as respostas produtivas referentes às condições de cultivo em sequeiro e sob ótima disponibilidade hídrica, sendo realizada análise temporal e de rentabilidade anual. Os modelos Cropgro-Soybean, Ceres-Maize e Cropgro-Drybean, obtiveram desempenho enquadrado como muito bom, muito bom e bom, para simulação da produção de grão (PG) das culturas da soja, milho e feijão, respectivamente e ótimo para simulação da produção de matéria seca máxima (MSM) de todas as culturas. Na comparação entre respostas produtivas à campo versus modelos disponíveis no sistema DSSat e no RSAP, observou-se que para as culturas da soja e feijão, as simulações realizadas com o DSSat obtiveram menores variações para a soja, e o RSAP para o feijão, porém, ambos os sistemas apresentaram variações consideradas satisfatórias. Para as simulações históricas, na condição de sequeiro, as três culturas estudadas (soja, milho e feijão), apresentaram significativas reduções de produção e consequente lucro em função do déficit hídrico. Em ambas as condições de cultivos (sequeiro e irrigado) os maiores custos; renda e lucro estiveram associado a cultura do milho, seguidos pelo feijão e soja. Comparando cultivo irrigado com o de sequeiro, a cultura do feijão foi a que apresentou maiores elevações de lucro em função da complementação hídrica, seguidas pelas culturas do milho e soja . Conclui-se que os modelos de simulação apresentaram-se como ferramentas úteis para a determinação das respostas produtivas das culturas em estudo, sendo que comparado cultivos de sequeiro com irrigados, os últimos apresentaram-se mais interessantes técnica e economicamente.
120

Simulační modely penzijního připojištění vzhledem k demografickému vývoji v ČR / Simulation models of pension insurance due to demographic development in the CR

Pudil, Lubomír January 2008 (has links)
The issue of an aging population, pension systems and pension themselves, are currently very actual, interesting and socially topics discussed. In my diploma thesis on simulation models of pension insurance due to demographic development in the CR I used simulation experiments, including those based primarily on the Monte Carlo method, tackling issues and negatives surrounding pension insurance with state contribution, which, as one of the financial products market, is the second pillar of pension system in the Czech Republic. Pension scheme of pension insurekce with state contibution gives participants the advantages and benefits in the form of state subsidy, the possibility of reducing the income tax base on the part of the contributions paid, proceeds from fund management and the possibility of contributions from the employer. On the other hand, play an important role, weaknesses and shortcomings of this system. Again, the most important may be considered inseparateness fund's assets from an estate participants, inappropriately designed state contribution, the high average age of participants and relatively low rate of return on fund management. Negatives mentioned above were reflected in the simulation experiments, when the linear state contribution was designed and was considered for the new system of pension saving in combination with a linear state contribution, which appears to be a more appropriate and beneficial for both participants on the one hand, and the state (impact on public spendings) on the other.

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