• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 94
  • 57
  • 16
  • 7
  • 6
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 221
  • 221
  • 52
  • 46
  • 34
  • 33
  • 24
  • 22
  • 21
  • 19
  • 19
  • 18
  • 18
  • 17
  • 16
  • 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.
181

Analise espacial e multicriterial da qualidade das lavouras de milho "Safrinha" no medio Paranapema / Spatial ana lyze and multicriteria evaluation of agricultural quality off-season maize "Safrinha" in middle Paranapema river valley, SP, Brazil

Dias, Hugo de Souza 14 December 2006 (has links)
Orientador: Rubens A. C. Lamparelli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-09T11:52:38Z (GMT). No. of bitstreams: 1 Dias_HugodeSouza_D.pdf: 5685544 bytes, checksum: 3cf72b0dbfd181c88c6ebe9be676447d (MD5) Previous issue date: 2006 / Resumo: Apesar do milho "safrinha" já representar uma grande proporção do milho produzido no Brasil e ter tido um significativo aumento de produtividade nos últimos anos, esta cultura ainda é relacionada ao baixo uso de tecnologia e à baixa produtividade. A primeira etapa deste estudo analisa as estatísticas e as relações entre os seguintes itens de verificação da qualidade das lavouras: data de semeadura; cobertura morta do solo; espaçamento das entrelinhas; estande e população de plantas; plantas problema; espaços entreplantas; infestação de ervas daninhas e perdas de colheita. A segunda etapa analisou a correlação espacial destas variáveis entre os diferentes talhões amostrados e mapeou a sua distribuição através das ferramentas da geoestatística na região do Médio Paranapanema. Na terceira etapa as variáveis foram utilizadas como critérios em uma avaliação multicriterial gerando um mapa de qualidade das lavouras. O método de polígonos de Thiessen foi utilizado no desagrupamento das estatísticas básicas (média, variância, assimetria), minimizando os problemas originados pela não aleatoriedade espacial da amostragem. O sistema de Plantio Direto (PD) foi discriminado estatisticamente do sistema de Preparo Convencional (PC) através de diversas variáveis, mas apenas a cobertura morta discriminou o PD da Semeadura na Palha de Inverno (SPi) e do PC. Oitenta e cinco por cento dos talhões avaliados tinham estande dentro dos limites aceitáveis e boa distribuição de plantas. Sessenta por cento dos itens de verificação apresentaram continuidade espacial entre talhões, o que permitiu o mapeamento através de krigagem ordinária. As áreas não ocupadas com milho foram retiradas da análise espacial utilizando-se uma máscara do uso da terra produzida pela classificação de imagens de satélite. A análise multicriterial (MCE) combinou o processo de análise hierárquica (AHP), para dar pesos aos critérios, e conjuntos fuzzy, para normalizar os critérios, possibilitando a avaliação e o mapeamento da qualidade das lavouras de milho "safrinha" em uma área de 1.577 km2. Palavras chaves: sistemas de preparo de solo; auditoria de qualidade; polígonos de Thiessen; sistemas de suporte a decisão; processo de análise hierárquica (AHP) / Abstract: Even though off-season or winter maize ("safrinha") today accounts for a large fraction of Brazilian maize production, and has displayed a significant increase in yield during the past few years, this crop is still associated with low technology and low yield. The first part of this study analyzes the statistics and relations among several variables of agricultural quality (items of quality verification): planting date; crop mulch cover; row spacing; plant stand and population; problem plants; plant spacing; weed infestation; harvest losses. The second part analyzes the spatial correlation of these variables among different plots sampled and maps the distribution by using spatial statistical tools in the Middle Paranapanema River Valley. In the third part, the variables were used as criteria in a multicriteria evaluation (MCE) that created an agricultural quality maps. Thiessen polygons were used to declustering the basic statistics (mean, variance, coefficient of skewness), minimizing problems introduced by non-random spatial sampling. No-tillage cultivation was statistically discriminated from conventional tillage by several variables, but only crop mulch cover separated no-tillage from winter crop mulch cultivation and conventional tillage. Eighty-five percent of plots studied had stands within acceptable limits and displayed good distribution of plants. Sixty percent of the variables showed spatial continuity among the plots, which permitted mapping by use ordinary kriging. Areas not planted in maize were removed from the spatial analysis using a mask of land use produced by a classification of satellite imagery. Multicriteria evaluation (MCE) combined the Analytic Hierarchy Process (AHP) to weight the criteria, and fuzzy sets were used to normalize the criteria, permitting the evaluation and mapping of agricultural quality of off-season ¿safrinha¿ maize in an area of 1,577 km2. Index terms: tillage systems; quality audit; Thiessen polygons; decision making; analytic hierarchy process (AHP) / Doutorado / Planejamento e Desenvolvimento Rural Sustentável / Doutor em Engenharia Agrícola
182

Sistemas dinamicos em espaços metricos fuzzy : aplicações em biomatematica / Dynamical systems in fuzzy metric spaces : applications in biomathematics

Cecconello, Moiseis dos Santos 15 August 2018 (has links)
Orientadores: Rodney Carlos Bassanezi, Adilson Jose Vieira Brandão / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-15T01:52:00Z (GMT). No. of bitstreams: 1 Cecconello_MoiseisdosSantos_D.pdf: 62393038 bytes, checksum: b7f0d1f9138d8e787749532bf661d026 (MD5) Previous issue date: 2010 / Resumo: Neste trabalho desenvolvemos ferramentas de análise qualitativa para sistemas dinâmicos definidos sobre o espaço formado pelos conjuntos fuzzy com a níveis compactos e não vazios. São propostas condições para existência de pontos de equilíbrio para o fluxo fuzzy cuja função de pertinência é sobrejetiva, generalizando alguns resultados já conhecidos. Os fluxos fuzzy considerados aqui são determinados pela extensão de Zadeh aplicada em soluções de equações diferenciais autônomas. São obtidos também condições para a existência de pontos e órbitas periódicas para o fluxo fuzzy. Em particular, demonstramos um teorema tipo Poincaré-Bendixson para tais fluxos gerados por equações autônomas bidimensionais. A análise qualitativa desenvolvida é aplicada em sistemas dinâmicos fuzzy provenientes de modelos significativos da Biomatemática. / Abstract: In this work we develop some tools for qualitative analysis of dynamical systems defined on the metric space of fuzzy sets with compact and nonempty a cuts. Conditions are offered for the existence of equilibrium points for the flow whose fuzzy membership function is surjective, generalizing some results already known. Fuzzy flows considered here are determined by Zadeh's extension applied in solutions of autonomous differential equations. We also obtained conditions for the existence of periodic points and periodic orbits for the fuzzy flow. In particular, we demonstrate a theorem like Poincaré-Bendixson for such flows generated by two-dimensional autonomous equations. The qualitative analysis results are applied to fuzzy dynamic systems from meaningful models of Biomathematics. / Doutorado / Biomatematica / Doutor em Matemática Aplicada
183

Fluxo de carga trifasico com modelagem de incertezas via função de pertinencia sinusoidal / Three-phase power flow with modelling of sinusoidal membership function

Cavalcante, Patricia Lopes 15 August 2018 (has links)
Orientador: Carlos Alberto Favarin Murari / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-15T17:14:22Z (GMT). No. of bitstreams: 1 Cavalcante_PatriciaLopes_M.pdf: 1174790 bytes, checksum: 78d8b398780924e7f52ce9c0e64a337f (MD5) Previous issue date: 2010 / Resumo: Neste trabalho é proposta uma versão fuzzy de fluxo de carga trifásico desbalanceado para redes de distribuição de energia elétrica. As características peculiares destas redes foram consideradas para tornar a solução o mais direta possível. Devido às técnicas específicas implementadas neste método, a decomposição LU e a substituição backward/forward da matriz Jacobiana, requeridas em métodos tradicionais, não são necessárias. O objetivo principal deste fluxo de carga é alcançar resultados que consideram as incertezas nas variáveis dos sistemas de potência. É utilizada uma função sinusoidal (forma de sino) ao invés de outras funções de pertinência, como por exemplo a trapezoidal e a triangular, para representar os números nebulosos e simular o fluxo de carga fuzzy. A função sinusoidal não requer técnicas adicionais como por exemplo, a-cortes e linearização, pois possui seus próprios operadores nebulosos. Para a validação do método proposto, resultados para diferentes redes são apresentados / Abstract: A fuzzy direct approach for unbalanced three-phase distribution load flow solutions was developed in this work. The special topological characteristics of distribution networks have been fully utilized to make the direct solution possible. Due to the distinctive solution techniques of the proposed method, the time-consuming LU decomposition and forward/backward substitution of the Jacobian matrix or admittance matrix required in the traditional load flow methods are no longer necessary. The main objective of this load flow is to get results which consider the vagueness in the power system's variables. The three-phase fuzzy load flow uses the bell shape function instead of others common membership functions, like trapezoidal and triangular, to represent fuzzy numbers and simulate a fuzzy load flow. The bell shape function doesn't require additional techniques like a-cuts and linearization to execute a fuzzy load flow because this function has proper operators. Test results demonstrate the validity of the proposed method / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica
184

Estudo da progressão da diabetes e da neuropatia periférica: classificação da severidade e caracterização cinética da locomoção / Study of the progression of diabetes and peripheral neuropathy: classification of the severity and kinetic characterization of locomotion

Andreja Paley Picon 28 February 2012 (has links)
Esta tese assumiu a premissa de que a neuropatia periférica é um sinal de piora da diabetes, além de levantar a questão de que estudos prévios sobre a biomecânica da marcha de diabéticos não têm distinguido os graus de progressão da diabetes nos grupos estudados. Neste contexto, não é possível identificar as diferenças nos padrões de geração da marcha entre estágios precoces e avançados da diabetes. Esta identificação poderia facilitar a intervenção terapêutica precoce nestes pacientes, o que poderá impedir a formação de úlceras e amputações recorrentes subseqüentes. Assim, apresentamos ao longo desta tese, três estudos para investigar a natureza das supostas alterações na marcha (estudo 1) e no descer escadas (estudo 2) de diabéticos, assim como para propor uma forma de classificar a progressão da diabetes levando em consideração as incertezas de fronteiras entre os subgrupos de neuropatas, por meio de um sistema especialista fuzzy (estudo 3). Os estudos 1 e 2 foram feitos com os mesmos três grupos: indivíduos diabéticos (GD) e diabéticos neuropatas (GDN) diagnosticados clinicamente e indivíduos saudáveis (GC). Para a avaliação cinemática e cinética do membro inferior foram utilizadas câmeras infravermelhas e uma plataforma de força durante o andar no plano e descendo uma escada. O cálculo dos momentos articulares de membro inferior foi feito por meio do método da dinâmica inversa. Os principais resultados do estudo 1 mostraram que independente da presença da neuropatia, os pacientes diabéticos exibiram uma maior flexão das três principais articulações do membro inferior e um importante uso da articulação do quadril como uma estratégia cinética de progressão do corpo à frente, em substituição ao tornozelo, que mostrou ser a articulação mais prejudicada. Os principais resultados do estudo 2 indicaram as mesmas mudanças significativas no padrão cinemático do tornozelo durante a fase de propulsão, mesmo na ausência da neuropatia. No entanto, não houve diferença nos padrões cinéticos entre os estágios iniciais e avançados da doença, mas mostraram a mesma tendência observada no estudo 1 de alteração do padrão cinético de quadril para se adaptar às perdas distais nos neuropatas. No estudo 3, desenvolvemos um modelo para classificação da severidade da neuropatia diabética. O modelo fuzzy apresentou um nível de concordância adequado com a classificação feita por especialistas, e também mostrou uma alta precisão na avaliação de pacientes reais que foram submetidos à avaliação do modelo. O modelo foi capaz de simplificar e separar os pacientes em quatro diferentes graus de severidade, o que pode melhorar a eficácia de medidas preventivas, bem como para oferecer uma melhor ajuda para os profissionais de saúde no tratamento destas doenças e suas complicações. Como conclusão geral temos que os grupos diabéticos estudados exibiram comportamentos biomecânicos durante o andar no plano e descendo degraus que são muitas vezes parecidos entre si (GD e GDN), poucas vezes diferentes entre si, mas na maioria das vezes bem distintos do grupo não diabético (GC), indicando que a questão da progressão não se esclareceu completamente ao separamos de maneira crisp os grupos em diabético e diabético neuropata. As perdas sensitivo-motoras-autonômicas impostas pela diabetes não podem ser subestimadas, uma vez que parecem ter início ainda quando a neuropatia não foi diagnosticada. Uma correta classificação do paciente pode antecipar a detecção dos níveis menos severos da doença, evitando esperar que os pacientes apresentem perdas irreversívies para inicar uma intervenção clínica eficaz e preventiva para preservar a locomoção independente destes pacientes / This study assumed the premise that the peripheral neuropathy is a sign of worsening of diabetes, as well as raising the issue that previous studies on the biomechanics of gait in diabetics do not have distinguished the degree of progression of diabetes in both groups. Therefore, it is not possible to identify differences in patterns of gait generation between early and advanced stages of diabetes. This identification would facilitate early therapeutic intervention in these patients, which could prevent the formation of recurrent ulcers and subsequent amputations. We present throughout this thesis, three studies to investigate the nature of the alleged changes in gait (study 1) and stair descent (study 2) of diabetics, and to propose a way to classify the progression of diabetes, taking into account the uncertainties of boundaries between the subgroups of neuropathy through a fuzzy expert system (study 3). Studies 1 and 2 were performed with the same three groups: diabetics (GD) and diabetic neuropathic (GDN) diagnosed clinically and healthy subjects (CG). For the kinematic and kinetic evaluation of the lower limb, we used infrared cameras and a force plate during walking on a level walkway (10 m) and descent a staircase. The calculation of net joint moments of the lower limb was performed using the method of inverse dynamic. The main results of Study 1 showed that, regardless of the presence of neuropathy, diabetic patients exhibited a greater flexion of the three major joints of the lower limb and an important use of the hip joint as a kinetic strategy of progression the body forward, replacing the ankle, which proved to be the most affected joint. The main results of Study 2 showed the same significant changes in the pattern of the ankle kinematics during propulsion phase, even in the absence of neuropathy. However, there was no difference between the kinetic patterns in early and advanced stages of the disease, but showed the same trend observed in the Study 1: a change in the kinetic pattern of the hip to adapt de locomotion to distal loss in neuropathic subjects. In Study 3, the model developed for classification of severity of diabetic neuropathy showed an adequate level of agreement with the classification of experts, and also showed a high accuracy in the evaluation of real patients who underwent to the evaluation of the model. The fuzzy model was able to simplify and separate the patients into four different degrees of severity, which can improve the effectiveness of preventive strategies as well as to offer a better assistance to health professionals in the management of this disease. It is concluded that the studied diabetic groups exhibited biomechanical behavior during walking and descend stairs that are often similar to each other (GD and GDN), a few times different from each other, but most often very different from the non-diabetic group (GC), indicating that the issue of progression was not fully understood separating the groups in a crisp way as diabetic and diabetic neuropathic subjects. The sensory, motor and autonomic losses imposed by the diabetes can not be underestimated, since they seem to appear when the neuropathy is not diagnosed yet. A correct classification of the patient can anticipate the detection of less severe levels of the disease and avoid that the patients show an irreversible loss to start an effective intervention and preventive strategies to keep the independent locomotion of these patients
185

'Theta'-FAMs : memórias associativas fuzzy baseadas em funções-'theta' / 'Theta'-FAMs : fuzzy associative memories based on functions-'theta'

Esmi, Estevão, 1982- 25 August 2018 (has links)
Orientador: Peter Sussner / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-25T00:54:31Z (GMT). No. of bitstreams: 1 Esmi_Estevao_D.pdf: 1836434 bytes, checksum: 5c3a2879200ff2c7bb59b21e24a173fc (MD5) Previous issue date: 2014 / Resumo: Muitas das memórias associativas fuzzy (FAMs) da literatura correspondem a redes neurais com uma única camada de pesos que armazenam de forma distributiva as informações das associações desejadas. As principais aplicações deste tipo de mémorias associativas são encontradas em sistemas baseados em regras fuzzy. Nesta tese introduzimos a classe de memórias associativas fuzzy-T (T-FAMs) que, em contraste com estes outros modelos, representam redes neurais fuzzy com duas camadas. Caso particulares de T-FAMs, denominadas S-FAMs (duais) e E-FAMs, são baseadas em medidas de subsethood e equivalência fuzzy. Resultados gerais sobre a capacidade de armazenamento e a capacidade de correção de erro das T-FAMs também foram providenciados. Adicionalmente, introduzimos um algoritmo geral de treinamento para T-FAM cuja convergência é sempre garantida. Apresentamos ainda um algoritmo alternativo para treinamento de uma certa classe de E-FAMs que além de ajustar os seus parâmetros também determina automaticamente a topologia da rede. Finalmente, comparamos as taxas de classificação produzidas pelas T-FAMs com alguns classificadores bem conhecidos em diversos problemas de classificação disponíveis na internet. Além disso, aplicamos com sucesso as T-FAMs em um problema de auto-localização de robô móvel baseado em visão / Abstract: Most fuzzy associative memories in the literature correspond to neural networks with a single layer of weights that distributively contains the information about the associations to be stored. The main applications of these types of associative memory can be found in fuzzy rule-base systems. In contrast, we present in this thesis the class of T-fuzzy associative memories (T-FAMs) that represent fuzzy neural networks with two layers. Particular cases of T-FAMs, called (dual) S-FAMs and E-FAMs, are based on fuzzy subsethood and equivalence measures. We provide theoretical results concerning the storage capability and error correction capability of T-FAMs. Furthermore, we introduce a general training algorithm for T-FAM that is guaranteed to converge in a finite numbers of iterations. We also proposed another alternative training algorithm for a certain type of E-FAM that not only adjusts the parameters of the corresponding network but also automatically determines its topology. We compare the classification rates produced by T-FAMs with that ones of some well-known classifiers in several benchmark classification problems that are available on the internet. Finally, we successful apply T-FAM approach to a problem of vision-based selflocalization in mobile robotics / Doutorado / Matematica Aplicada / Doutor em Matemática Aplicada
186

Decomposição de Dantzig-Wolfe e heurística aplicados a problemas de fluxo multiproduto Fuzzy / Decomposition's Dantzig-Wolfe and heuristic applied to fuzzy multicommodity flow problems

Ciappina, Jussara Rodrigues 19 August 2018 (has links)
Orientadores: Akebo Yamakami, Ricardo Coelho Silva / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T06:43:21Z (GMT). No. of bitstreams: 1 Ciappina_JussaraRodrigues_D.pdf: 6752680 bytes, checksum: 3dcb7910cc5098e44936e76045792069 (MD5) Previous issue date: 2011 / Resumo: Este trabalho apresenta dois métodos baseados no método clássico de decomposição de Dantzig-Wolfe e um método heurístico, os quais resolvem problemas com incertezas nos parâmetros utilizando a teoria dos conjuntos fuzzy. O primeiro aborda incertezas somente nos custos, enquanto que, os outros dois abordam incertezas nos custos e nas restrições. Métodos que utilizam técnicas de decomposição são indicados para resolver problemas de grande porte que apresentam uma estrutura especial em uma parte do conjunto das restrições. Um exemplo de problema que apresenta tal estrutura é o problema de fluxo multiproduto. Este problema pode ser modelado através de um grafo, cujos nós representam pontos de oferta, demanda e passagem de produtos que trafegam pelos arcos da rede. O objetivo é determinar o fluxo de cada produto nos arcos, de modo a atender a demanda a um custo mínimo, respeitando as restrições de capacidade dos arcos e as restrições de conservação de fluxo dos nós. Com exceção do terceiro, os demais métodos propostos neste trabalho não se limitam a resolver problemas de fluxo multiproduto fuzzy, também resolvem problemas de programação linear fuzzy que apresentam uma estrutura especial em uma parte do conjunto das restrições / Abstract: In this work we present two methods based in the classical Dantzig-Wolfe decomposition and a heuristic method, which solve problems with uncertainties in the parameters using the theory of fuzzy sets. The first one deals with uncertainties only in costs, while the others two deal with uncertainties in costs and restrictions. Methods using decomposition techniques address problems that have a special structure in the set of restrictions. An example of such a problem that has this structure is the fuzzy multicommodity flow problem. This problem can be modeled by a graph whose nodes represent points of supply, demand and passage of commodities that travel by the arcs of the network. The objective is to determine the flow of each commodity in the arcs, in order to meet demand at a minimal cost while respecting the capacity restrictions of the arcs and the flow conservation restrictions of the nodes. With the exception of the third, the other methods proposed in this work are not limited to solve fuzzy multicommodity flow problems, also solve fuzzy linear programming problems that have a special structure in a part of the set of restrictions / Doutorado / Automação / Doutor em Engenharia Elétrica
187

A contribution to enterprise interoperability maturity assessment / Contribution à l'évaluation de la maturité de l'interopérabilité d'entreprise

Guedria, Wided 09 July 2012 (has links)
Ce travail entre dans le cadre de la problématique générale du développement de l’interopérabilité d’entreprise. De nombreux modèles, méthodes, méthodologies et outils existants pour aider une organisation, une entreprise, ou plus généralement un système, à développer l’interopérabilité avec ses partenaires. Cependant, la plupart des approches existantes portent principalement sur les solutions informatiques. Des recherches fondamentales en amont permettant de caractériser et mesurer le potentiel d’une entreprise à interopérer sont encore largement insuffisantes. Cette thèse s’intéresse en particulier à la définition des métriques pour évaluer le potentiel de l’interopérabilité d’une entreprise. En se focalisant spécifiquement sur la maturité d’interopérabilité, un modèle de maturité pour l’interopérabilité d’entreprise (MMEI) a été élaboré. Le MMEI est basé sur les modèles de maturité existants et couvre les principaux aspects et dimensions de l’interopérabilité d’entreprise. Les théories scientifiques existantes, notamment la théorie générale du système, considérée comme la plus pertinente pour l’interopérabilité, ont été étudiées et leurs concepts de base ont été pris en compte. Une ontologie, permettant de définir formellement le domaine de l’interopérabilité d’entreprise, a été également proposée. C’est sur cette ontologie que le MMEI a été construit et développé. / This work fits within the framework of the general problematic of the enterprise interoperability development. Many models, methods, methodologies and tools exist to help an organization, an enterprise, or more generally a system, to develop interoperability with its partners. However, most of existing works in this domain have been done to develop operational solutions to solve interoperability problems. Basic and fundamental researches, allowing characterizing and measuring the potential of an enterprise to interoperate, are still missing. In particular, this thesis deals with the definition of metrics for evaluating enterprise interoperability. By focusing specifically on interoperability maturity, a Maturity Model for Enterprise Interoperability (MMEI) is elaborated. The proposed MMEI is based on existing relevant maturity models and extends existing works to cover all main aspects and dimensions of enterprise interoperability. Possible contribution from existing scientific theories, in particular General System Theory considered as most relevant, are investigated and core concepts are brought into MMEI. An ontology of enterprise interoperability is also proposed to formalize basic concepts of enterprise interoperability. Based on this ontology, the MMEI has been, thereafter, developed.
188

Fuzzy State Reservoir Operation Models For Irrigation

Kumari, Sangeeta 18 July 2016 (has links) (PDF)
Efficient management of limited water resources in an irrigation reservoir system is necessary to increase crop productivity. To achieve this, a reservoir release policy should be integrated with an optimal crop water allocation. Variations in hydrologic variables such as reservoir inflow, soil moisture, reservoir storage, rainfall and evapotranspiration must be considered in the reservoir operating policy model. Uncertainties due to imprecision, subjectivity, vagueness and lack of adequate data can be handled using the fuzzy set theory. A fuzzy stochastic dynamic programming (FSDP) model with reservoir storage and soil moisture of the crops as fuzzy state variables and inflow as a stochastic variable, is developed to obtain a steady state reservoir operating policy. The model integrates the reservoir operating policy with the crop water allocation decisions by maintaining the storage continuity and the soil moisture balance. The reservoir release decisions are made in the model in 10-day periods and water is allocated to the crops on a daily basis. On comparison with the classical stochastic dynamic programming (SDP) model and a conceptual operation policy model, it is observed that the FSDP model, in general, results in lower release from the reservoir while maintaining lower soil moisture stress. However the steady state reservoir operation policy obtained using the FSDP model may not perform well in a short-term reservoir simulation. A fuzzy state short-term reservoir operation policy model with storage and soil moistures of the crops as fuzzy variables, is developed to obtain a real time release policy using forecasted inflow and forecasted rainfall. The distinguishing features of the model are accounting for (a) spatial variation of soil moisture and rainfall using gridded rainfall forecasts and (b) ponding depth requirement of the Paddy. On comparison with a conceptual operation policy model, the fuzzy state real time operation model is found most suitable for the application of the short term real time operation for irrigation. The real time operation model maintains high storage in the reservoir during most of the 10-day time periods of a year and results in a slightly lower annual releases as compared to the conceptual operation policy model. The effect of inflow forecast uncertainty is examined using different sets of forecasted inflows, and it is observed that the system performance is quite sensitive to inflow forecast uncertainties. The use of the satellite based gridded soil moisture in the real time operation model shows consideration of realistic situations. Further, three performance measures, viz., fuzzy reliability, fuzzy resiliency and fuzzy vulnerability are developed to evaluate the performance of the irrigation reservoir system under a specified operating policy. A fuzzy set with an appropriate membership function is defined to describe the working and failed states to account for the system being in partly working and partly failed state. The degree of failure of the irrigation reservoir system is defined based on the evapotranspiration deficit in a period. Inclusion of fuzziness in the performance measures enables realistic representation of uncertainties in the state of the system. A case study of Bhadra reservoir system in Karnataka, India is chosen for demonstrating the model applications.
189

Evaluating of Fuzzy Clustering Results / Hodnocení Výsledků Fuzzy Shlukování

Říhová, Elena January 2013 (has links)
Cluster analysis is a multivariate statistical classification method, implying different methods and procedures. Clustering methods can be divided into hard and fuzzy; the latter one provides a more precise picture of the information by clustering objects than hard clustering. But in practice, the optimal number of clusters is not known a priori, and therefore it is necessary to determine the optimal number of clusters. To solve this problem, the validity indices help us. However, there are many different validity indices to choose from. One of the goals of this work is to create a structured overview of existing validity indices and techniques for evaluating fuzzy clustering results in order to find the optimal number of clusters. The main aim was to propose a new index for evaluating the fuzzy clustering results, especially in cases with a large number of clusters (defined as more than five). The newly designed coefficient is based on the degrees of membership and on the distance (Euclidean distance) between the objects, i.e. based on principles from both fuzzy and hard clustering. The suitability of selected validity indices was applied on real and generated data sets with known optimal number of clusters a priory. These data sets have different sizes, different numbers of variables, and different numbers of clusters. The aim of the current work is regarded as fulfilled. A key contribution of this work was a new coefficient (E), which is appropriate for evaluating situations with both large and small numbers of clusters. Because the new validity index is based on the principles of both fuzzy clustering and hard clustering, it is able to correctly determine the optimal number of clusters on both small and large data sets. A second contribution of this research was a structured overview of existing validity indices and techniques for evaluating the fuzzy clustering results.
190

Selecting Optimal Residential Locations Using Fuzzy GIS Modeling

Tang, Zongpei 12 1900 (has links)
Integrating decision analytical techniques in geographic information systems (GIS) can help remove the two primary obstacles in spatial decision making: inaccessibility to required geographic data and difficulties in synthesizing various criteria. I developed a GIS model to assist people seeking optimal residential locations. Fuzzy set theory was used to codify criteria for each factor used in evaluating residential locations, and weighted linear combination (WLC) was employed to simulate users' preferences in decision making. Three examples were used to demonstrate the applications in the study area. The results from the examples were analyzed. The model and the ArcGIS Extension can be used in other geographic areas for residential location selection, or in other applications of spatial decision making.

Page generated in 0.0568 seconds