Dissertations / Theses on the topic 'NEURO-FUZZY ANFIS'

The thesis deals with artificial neural networks theory. Subsequently, fuzzy sets are being described and fuzzy logic is explained. The hybrid neuro-fuzzy system stemming from ANFIS system is designed on the basis of artificial neural networks, fuzzy sets and fuzzy logic. The upper-mentioned systems' functionality has been demonstrated on an inverted pendulum controlling problem. The three controllers have been designed for the controlling needs - the first one is on the basis of artificial neural networks, the second is a fuzzy one, and the third is based on ANFIS system.  The thesis is aimed at comparing the described systems, which the controllers have been designed on the basis of, and evaluating the hybrid neuro-fuzzy system ANFIS contribution in comparison with particular theory solutions. Finally, some experiments with the systems are demonstrated and findings are assessed.

Medical prognosis is the prediction of the future course and outcome of a disease and an indication of the likelihood of recovery from that disease. Prognosis is important because it is used to guide the type and intensity of the medication administered to patients. Patients are usually concerned with how long they will survive after diagnosis. Survival analysis describes the analysis of data that corresponds to the time from when an individual enters a study until the occurrence of some particular event or end-point. It is concerned with the comparison of survival curves for different combinations of risk factors. Analytical methods that are transparent for the clinician's understanding and explain individual inferences need to be considered when dealing with medical data. This thesis describes a methodology for modelling survival by utilising the application of the Adaptive Neuro-Fuzzy Inference System (ANFIS). A hybrid intelligent system which combines the fuzzy logic qualitative approach and adaptive neural network capabilities towards better performance. The ANFIS approach was applied in modelling survival of breast cancer based on patient groups derived from the Nottingham Prognostic Index (NPI). A comparison of the proposed method with the existing methods in the capability to predict the survival rate is presented. The use of a fuzzy inference system (FIS) in modelling survival is expected to offer the capability to deliver the process of turning data into knowledge that can be understood by people. The design of rules can be performed either by human experts or using appropriate approaches to build high quality PIS to represent the knowledge. In this thesis, represent an automatic generation of membership functions and rules from the data. Further, corresponding subsequent adjustments have been made to the model to give towards more satisfactory performance. The final premise and consequent parameters obtained are then used to predict the survival for each time interval. A framework for modelling survival with the application of fuzzy inference system and back-propagation neural network was developed and is described in this thesis. In this framework, a different way of partitioning the input space can be selected to define the membership functions for examples using expert knowledge, equaliser partitioning, fuzzy c-means or subtractive clustering techniques. Further, the rule base can be established by enumerating all possible combinations of membership functions of all inputs. After the initialisation of the fuzzy inference structure, the replication data (until time to event) will be subject to training using the gradient descent and nonnegative least square algorithm to estimate the conditional event probability. This framework is validated over a synthetic dataset and a novel dataset of patients following operative surgery of ovarian cancer. The proposed framework can be applied to estimate the hazard and survival curve between different prognostic factors and survival time with the explanation capabilities.

Neuro-Fuzzy systems are the systems that neural networks (NN) are incorporated in fuzzy systems, which can use knowledge automatically by learning algorithms of NNs. They can be viewed as a mixture of local experts. Adaptive Neuro-Fuzzy inference system (ANFIS) is one of the examples of Neuro Fuzzy systems in which a fuzzy system is implemented in the framework of adaptive networks. ANFIS constructs an input-output mapping based both on human knowledge (in the form of fuzzy rules) and on generated input-output data pairs. Effective control for distillation systems, which are one of the important unit operations for chemical industries, can be easily designed with the known composition values. Online measurements of the compositions can be done using direct composition analyzers. However, online composition measurement is not feasible, since, these analyzers, like gas chromatographs, involve large measurement delays. As an alternative, compositions can be estimated from temperature measurements. Thus, an online estimator that utilizes temperature measurements can be used to infer the produced compositions. In this study, ANFIS estimators are designed to infer the top and bottom product compositions in a continuous distillation column and to infer the reflux drum compositions in a batch distillation column from the measurable tray temperatures. Designed estimator performances are further compared with the other types of estimators such as NN and Extended Kalman Filter (EKF). In this study, ANFIS performance is also investigated in the adaptive Neuro-Fuzzy control of a pH system. ANFIS is used in specialized learning algorithm as a controller. Simple ANFIS structure is designed and implemented in adaptive closed loop control scheme. The performance of ANFIS controller is also compared with that of NN for the case under study.

Heart signals allow for a comprehensive analysis of the heart. Electrocardiography (ECG or EKG) uses electrodes to measure the electrical activity of the heart. Extracting ECG signals is a non-invasive process that opens the door to new possibilities for the application of advanced signal processing and data analysis techniques in the diagnosis of heart diseases. With the help of today’s large database of ECG signals, a computationally intelligent system can learn and take the place of a cardiologist. Detection of various abnormalities in the patient’s heart to identify various heart diseases can be made through an Adaptive Neuro-Fuzzy Inference System (ANFIS) preprocessed by subtractive clustering. Six types of heartbeats are classified: normal sinus rhythm, premature ventricular contraction (PVC), atrial premature contraction (APC), left bundle branch block (LBBB), right bundle branch block (RBBB), and paced beats. The goal is to detect important characteristics of an ECG signal to determine if the patient’s heartbeat is normal or irregular. The results from three trials indicate an average accuracy of 98.10%, average sensitivity of 94.99%, and average specificity of 98.87%. These results are comparable to two artificial neural network (ANN) algorithms: gradient descent and Levenberg Marquardt, as well as the ANFIS preprocessed by grid partitioning.

Este trabalho apresenta uma alternativa ao controle vetorial de motores de indução, sem a utilização de sensores para realimentação da velocidade mecânica do motor. Ao longo do tempo, diversas técnicas de controle vetorial têm sido propostas na literatura. Dentre elas está a técnica de controle por orientação de campo (FOC), muito utilizada na indústria e presente também neste trabalho. A principal desvantagem do FOC é a sua grande sensibilidade às variações paramétricas da máquina, as quais podem invalidar o modelo e as ações de controle. Nesse sentido, uma estimativa correta dos parâmetros da máquina, torna-se fundamental para o acionamento. Este trabalho propõe o desenvolvimento e implementação de um estimador baseado em um sistema de inferência neuro-fuzzy adaptativo (ANFIS) para o controle de velocidade do motor de indução trifásico em um acionamento sem sensores. Pelo fato do acionamento em malha fechada admitir diversas velocidades de regime estacionário para o motor, uma nova metodologia de treinamento por partição de frequência é proposta. Ainda, faz-se a validação do sistema utilizando a orientação de campo magnético no referencial de campo de entreferro da máquina. Simulações para avaliação do desempenho do estimador mediante o acionamento vetorial do motor foram realizadas utilizando o programa Matlab/Simulink. Para a validação prática do modelo, uma bancada de testes foi implementada; o acionamento do motor foi realizado por um inversor de frequência do tipo fonte de tensão (VSI) e o controle vetorial, incluindo o estimador neuro-fuzzy, foi realizado pelo pacote de tempo real do programa Matlab/Simulink, juntamente com uma placa de aquisição de dados da National Instruments.
This work presents an alternative sensorless vector control of induction motors. Several techniques for induction motor control have been proposed in the literature. Among these is the field oriented control (FOC), strongly used in industries and also in this work. The main drawback of the FOC technique is its sensibility to deviations of the parameters of the machine, which can deteriorate the control actions. Therefore, an accurate determination of the machines parameters is mandatory to the drive system. This work proposes the development of an adaptive neuro-fuzzy inference system (ANFIS) estimator to control the angular speed of a three-phase induction motor in a sensorless drive. In a closed loop configuration, several speed commands can be imposed to the motor. Thus, a new frequency partition training of ANFIS is proposed. Moreover, the ANFIS speed estimator is validated in a magnetizing flux oriented control scheme. Simulations to evaluate the performance of the estimator considering the vector drive system were done by the Matlab/Simulink. To determine the benefits of the proposed model a practical system was implemented using a voltage source inverter (VSI) and the vector control including the ANFIS estimator, carried out by the Real Time Toolbox from Matlab/Simulink and a data acquisition card from National Instruments.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
This paper presents a new multi-model technique of dentification in ANFIS for nonlinear systems. In this technique, the structure used is of the fuzzy Takagi-Sugeno of which the consequences are local linear models that represent the system of different points of operation and the precursors are membership functions whose adjustments are realized by the learning phase of the neuro-fuzzy ANFIS technique. The models that represent the system at different points of the operation can be found with linearization techniques like, for example, the Least Squares method that is robust against sounds and of simple application. The fuzzy system is responsible for informing the proportion of each model that should be utilized, using the membership functions. The membership functions can be adjusted by ANFIS with the use of neural network algorithms, like the back propagation error type, in such a way that the models found for each area are correctly interpolated and define an action of each model for possible entries into the system. In multi-models, the definition of action of models is known as metrics and, since this paper is based on ANFIS, it shall be denominated in ANFIS metrics. This way, ANFIS metrics is utilized to interpolate various models, composing a system to be identified. Differing from the traditional ANFIS, the created technique necessarily represents the system in various well defined regions by unaltered models whose pondered activation as per the membership functions. The selection of regions for the application of the Least Squares method is realized manually from the graphic analysis of the system behavior or from the physical characteristics of the plant. This selection serves as a base to initiate the linear model defining technique and generating the initial configuration of the membership functions. The experiments are conducted in a teaching tank, with multiple sections, designed and created to show the characteristics of the technique. The results from this tank illustrate the performance reached by the technique in task of identifying, utilizing configurations of ANFIS, comparing the developed technique with various models of simple metrics and comparing with the NNARX technique, also adapted to identification
Este trabalho apresenta uma nova t?cnica de identifica??o multimodelos baseada em ANFIS para sistemas n?o lineares. Nesta t?cnica, a estrutura utilizada ? do tipo fuzzy Takagi-Sugeno cujos consequentes s?o modelos lineares locais que representam o sistema em diferentes pontos de opera??o e os antecedentes s?o fun??es de pertin?ncia cujos ajustes s?o realizados pela fase de aprendizagem da t?cnica neuro-fuzzy ANFIS. Modelos que representem o sistema em diferentes pontos de opera??o podem ser encontrados com t?cnicas de lineariza??o como, por exemplo, o m?todo dos M?nimos Quadrados que ? robusto a ru?dos e de simples aplica??o. Cabe ? fase de implica??o do sistema fuzzy informar a propor??o de cada modelo que deve ser empregada, utilizando, para isto, as fun??es de pertin?ncia. As fun??es de pertin?ncia podem ser ajustadas pelo ANFIS com o uso de algoritmos de redes neurais, como o de retropropaga??o do erro, de modo que os modelos encontrados para cada regi?o sejam devidamente interpolados e, assim, definam-se a atua??o de cada modelo para as poss?veis entradas do sistema. Em multimodelos a defini??o de atua??o de modelos ? conhecida por m?trica e, como neste trabalho ? realizada pelo ANFIS, ser? denominada de m?trica ANFIS. Desta forma, uma m?trica ANFIS ? utilizada para interpolar v?rios modelos, compondo o sistema a ser identificado. Diferentemente do ANFIS tradicional, a t?cnica desenvolvida necessariamente representa o sistema em v?rias regi?es bem definidas por modelos inalter?veis que, por sua vez, ter?o sua ativa??o ponderada a partir das fun??es de pertin?ncia. A sele??o de regi?es para a aplica??o do m?todo dos M?nimos Quadrados ? realizada manualmente a partir da an?lise gr?fica do comportamento do sistema ou a partir do conhecimento de caracter?sticas f?sicas da planta. Esta sele??o serve como base para iniciar a t?cnica definindo modelos lineares e gerando a configura??o inicial das fun??es de pertin?ncia. Experimentos s?o realizados em um tanque did?tico, com m?ltiplas se??es, projetado e desenvolvido com a finalidade de mostrar caracter?sticas da t?cnica. Os resultados neste tanque ilustram o bom desempenho alcan?ado pela t?cnica na tarefa de identifica??o, utilizando, para isto, v?rias configura??es do ANFIS, comparando a t?cnica desenvolvida com m?ltiplos modelos de m?trica simples e comparando com a t?cnica NNARX, tamb?m adaptada para identifica??o

The role of information technology (IT) applications has become critical for organisations in various sectors such as education, health, finance, logistics, manufacturing and project management. IT applications provide many advantages at strategic, management and operational levels, and the investment in IT applications is therefore growing; however, the failure rate of IT projects is still high, despite the development of theories, methodologies and frameworks for IT project management in recent decades. The consequences of failure of an IT project can be devastating, and can threaten the existence of an organisation. There are many different factors that impact on the performance of a project; these factors are varied and interrelated, and can impact project performance throughout the different phases of the project life cycle. The aims of this research are to (i) identify the critical failure factors (CFFs) of IT projects; (ii) categorise these CFFs; (iii) identify the relationships between CFFs; and (iv) develop a model using an adaptive neuro-fuzzy inference system (ANFIS) to forecast the failure of IT projects in the early stages. The primary data collection tool is a questionnaire, and the analysis is carried out with the ANFIS technique. ANFIS is a hybrid model that combines an artificial neural network (ANN) with learning algorithms and techniques, and uses fuzzy logic to extract fuzzy rules based on prior knowledge of past data. In this research, we develop 266 rules and then test the performance of the developed model using training data and checking data. In this way, the role structure of the ANFIS model is obtained, which can be used to forecast the failure of IT projects. The findings suggest that there are many failure factors that can impact negatively on the performance of IT projects. These factors can be categorised into organisational, project management, planning, project manager, project team, user/customer, technological and technical, and legal factors. The results show that CFFs related to the project team, planning and organisation have the highest impact on the failure of IT projects. The ANFIS model constructed here can help IT project managers to effectively address the risk associated with projects in the early phases and to forecast the failure percentage of IT projects. This research can enable managers and decision makers to predict failure early in the project, allowing them to take suitable decisions, and can provide policy makers with an innovative approach to enhance decision-making processes

Artificial intelligence techniques have been widely used for prediction in various areas of sciences and engineering. In the thesis, applications of AI techniques are studied to predict the dilution of industrial outfall discharges. The discharge of industrial effluents from the outfall systems is broadly divided into two categories on the basis of density. The effluent with density higher than the water receiving will sink and called as negatively buoyant jet. The effluent with density lower than the receiving water will rise and called as positively buoyant jet. The effluent discharge in the water body creates major environmental threats. In this work, negatively buoyant jet is considered. For the study, ANFIS model is taken into consideration and incorporated with algorithms such as GA, PSO and FFA to determine the suitable model for the discharge prediction. The training and test dataset for the ANFIS-type models are obtained by simulating the jet using the realizable k-ε turbulence model over a wide range of Froude numbers i.e. from 5 to 60 and discharge angles from 20 to 72.5 degrees employing OpenFOAM platform. Froude number and angles are taken as input parameters for the ANFIS-type models. The output parameters were peak salinity (Sm), return salinity (Sr), return point in x direction (xr) and peak salinity coordinates in x and y directions (xm and ym). Multivariate regression analysis has also been done to verify the linearity of the data using the same input and output parameters. To evaluate the performance of ANFIS, ANFIS-GA, ANFIS-PSO, ANFIS-FFA and multivariate regression model, some statistical parameters such as coefficient of determination (R2), root mean squared error (RMSE), mean absolute error (MAE) and average absolute deviation in percentage are determined. It has been observed that ANFIS-PSO is better in predicting the discharge characteristics.

Lakes present in arid regions of Central Anatolia need further attention with regard to water quality. In most cases, mathematical modeling is a helpful tool that might be used to predict the DO concentration of a lake. Deterministic models are frequently used to describe the system behavior. However most ecological systems are so complex and unstable. In case, the deterministic models have high chance of failure due to absence of priori information. For such cases black box models might be essential. In this study DO in Eymir Lake located in Ankara was modeled by using both Artificial Neural Networks (ANN) and Adaptive Neuro Fuzzy Inference System (ANFIS). Phosphate, Orthophospate, pH, Chlorophyll-a, Temperature, Alkalinity, Nitrate, Total Kjeldahl Nitrogen, Wind, Precipitation, Air Temperature were the input parameters of ANN and ANFIS. The aims of these modeling studies were: to develop models with ANN to predict DO concentration in Lake Eymir with high fidelity to actual DO data, to compare the success (prediction capacity) of ANN and ANFIS on DO modeling, to determine the degree of dependence of different parameters on DO. For modeling studies &ldquo
Matlab R 2007b&rdquo
software was used. The results indicated that ANN has high prediction capacity of DO and ANFIS has low with respect to ANN. Failure of ANFIS was due to low functionality of Matlab ANFIS Graphical User Interface. For ANN Modeling effect of meteorological data on DO data on surface of the lake was successfully described and summer month super saturation DO concentrations were successfully predicted.

Orientador: Suely Cunha Amaro Mantovani
Resumo: No estudo dos manipuladores são utilizados os conceitos da cinemática direta e a inversa. No cálculo da cinemática direta tem-se a facilidade da notação de Denavit-Hartenberg, mas o desafio maior é a resolução da cinemática inversa, que se torna mais complexa conforme aumentam os graus de liberdade do manipulador, além de apresentar múltiplas soluções. As variáveis angulares obtidas pelas equações da cinemática inversa são utilizadas pelo controlador, para posicionar o órgão terminal do manipulador em um ponto específico de seu volume de trabalho. Na busca de alternativas para contornar estes problemas, neste trabalho utilizam-se os Modelos Adaptativos de Inferência Neuro-Fuzzy - ANFIS para a resolução da cinemática inversa, por meio de simulações, para obter o posicionamento de um manipulador robótico de 5 graus de liberdade, composto por sete servomotores controlados pela plataforma de desenvolvimento Intel® Galileo Gen 2, usado como caso de estudo. Nas simulações usamse ANFIS com uma arquitetura com três e quatro funções de pertinência de entrada, do tipo gaussiana. O desempenho da arquitetura da ANFIS implementada foi comparado com uma Rede Perceptron Multicamadas, demonstrando com os resultados favoráveis a ANFIS, a sua capacidade de aprender e resolver com baixo erro quadrático médio e com precisão, a cinemática inversa para o manipulador em estudo. Verifica-se também, que a performance das ANFIS melhora, quanto à precisão dos resultados, demonstrado pelo desvio médio d... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In the study of manipulator’s, the concepts of direct and inverse kinematics are used. In the computation of forward kinematics, it has of the ease of Denavit-Hartenberg notation, but the biggest challenge is the resolution of the inverse kinematics, which becomes more complex as the manipulator's degrees of freedom increase, besides presenting multiple solutions. The angular variables obtained by the inverse kinematics equations are used by the controller to position the terminal organ of the manipulator at a specific point in its work volume. In the search for alternatives to overcome these problems, in this work, the Adaptive Neuro-Fuzzy Inference Models (ANFIS) are used to solve the inverse kinematics, by means of simulations, to obtain the positioning of a robot manipulator of 5 degrees of freedom, consisting of seven servomotors controlled by the Intel® Galileo Gen 2 development platform, used as a case's study . In the simulations ANFIS's architecture are used three and four Gaussian membership functions of input. The performance of the implemented ANFIS architecture was compared to a Multi-layered Perceptron Network, demonstrating with the favorable results the ANFIS, its ability to learn and solve with low mean square error and with precision, the inverse kinematics for the manipulator under study. It is also verified that the performance of the ANFIS improves, as regards the accuracy of the results in the training process, , demonstrated by the mean deviation of the... (Complete abstract click electronic access below)
Mestre

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Este trabalho apresenta uma modelagem para DHTv%, DHTi% e harmônicos individuais utilizando previsões de um sistema ANFIS que aprende com dados medidos e prevê o comportamento da rede para valores futuros. Estas previsões podem ajudar a atender as normas nacionais de DHTv% estipuladas pela Agência Nacional de Energia Elétrica (ANEEL) através dos Procedimentos de Distribuição (PRODIST), como as normas internacionais de DHTi%., desta forma se antecipando às normas que atualmente são recomendativas, mas em um futuro próximo serão punitivas. A modelagem é realizada por meio de um sistema Neuro-Fuzzy denominado ANFIS, o qual utiliza rede neural para aprender o comportamento do sistema e ajuste dos parâmetros e regra Fuzzy para a determinação dos valores de saída do sistema levando em consideração o aprendizado da rede Neural. A grande vantagem desta ferramenta é o poder de se modelar padrões utilizando uma previsão de estado harmônico das cargas conectadas na baixa tensão, o que ajuda na criação de pseudomedidas para as redes de distribuição, onde é difícil e oneroso a obtenção de medições reais. Entre as aplicações práticas para esta ferramenta pode-se destacar a utilização dos valores previstos em substituição a valores anômalos medidos, a utilização em medidores de energia para prever e evitar a ultrapassagem dos valores de Distorção Harmônico estipulados em norma e a utilização como base para a previsão de harmônicas individuais, que podem ser utilizadas em estudos de fluxo de carga harmônicos.
This work presents a modeling for THDv%, THDi% and individual harmonics using predictions from an ANFIS system that learns with measured data and predicts the behavior of the network for future values. These forecasts can help meet national THDv% standards stipulated by the Agência Nacional de Energia Elétrica (ANEEL) through Distribution Procedures (PRODIST), such as THDi% international standards, thus anticipating the currently recommended standards, but in the near future will be punitive. The modeling is performed by means of a Neuro-Fuzzy system called ANFIS, which uses neural network to learn the behavior of the system and adjustment of the parameters and Fuzzy rule for the determination of the system output values taking into account the learning of the Neural network. The great advantage of this tool is the power of modeling standards using a prediction of the harmonic state of the connected loads in the low voltage, which helps in the creation of pseudomedidas for the distribution networks, where it is difficult and costly to obtain real measurements. Among the practical applications for this tool is the use of the predicted values instead of measured anomalous values, the use in energy meters to predict and avoid exceeding the values of Harmonic Distortion stipulated in standard and the use as a basis for the prediction of individual harmonics that can be used in harmonic load flow studies.

Dissertação para obtenção do grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização Sustentáveis
Com os avanços conseguidos no campo de tecnologias de conversão de energias renováveis nos últimos 20 anos, e as escaladas no preço do petróleo dos últimos anos, tornou-se mais atractivo investir em tecnologias de conversão de energias renováveis, principalmente em sistemas eléctricos isolados de elevada disponibilidade de recursos renováveis, como é o caso do sistema eléctrico da ilha de Santiago em Cabo Verde, onde aumentou-se consideravelmente a penetração renovável nos últimos três anos. Contudo, sobretudo devido à variabilidade dos recursos e produção renovável, o aumento destas fontes nos sistemas eléctricos isolados acrescenta também desafios à tomada de decisão de optimização do despacho e reserva girante. Assim, é apresentado nesta dissertação um sistema inteligente que se baseia na lógica difusa (fuzzy logic) e sistema neuro-fuzzy (ANFIS) para optimizar automaticamente o despacho e reserva girante no Sistema Eléctrico Híbrido da Ilha de Santiago (SEHIS). O sistema proposto baseia-se na previsão do consumo e produção renovável, nomeadamente a produção eólica e fotovoltaica, e despacha automaticamente os geradores a fuelóleo com base nos seus custos de produção, por forma a permitir a máxima penetração renovável, reduzindo assim o consumo do fuelóleo e, consequentemente, o custo de produção. Além disso, o sistema proposto salvaguarda as restrições técnicas do sistema eléctrico, nomeadamente a reserva girante mínima necessária para fazer face à contingência ou erro de previsão, e ainda as restrições técnicas dos geradores, designadamente o limite mínimo de carga recomendado pelos fabricantes (50%), permitindo desta forma evitar a degradação da eficiência e aumento de avarias dos geradores.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A necessidade de aplicação de novos equipamentos em ambientes cada vez mais agressivos demandou a busca por novos produtos capazes de suportar altas temperaturas, inertes às corroções químicas e com alta rigidez mecânica. O avanço tecnógico na produção de materiais cerâmicos tornou possível o emprego de processos de fabricação que antes eram somente empregados em metais. Dentre os processos de usinagem de cerâmicas avançadas, a retificação é o mais utilizado devido às maiores taxas de remoção diferentemente do brunimento e das limitações geométricas do processo de lapidação. A rugosidade é um do parâmetros de saída do processo de retificação que influi, dentre outros fatores, na qualidade do deslizamento entre estruturas, podendo gerar aquecimento. Além disso, o desgaste da ferramenta de corte gerado durante o processo está associado aos custos fixos e a problemas relacionados com o acabamento superficial bem como a danos estruturais. Essas duas variáveis, rugosidade e desgaste, são objetos de estudos de muitos pesquisadores. Entretanto, o controle automático tem sido uma difícil tarefa de ser realizada devido às variações de parâmetros ocorridas no processo. Dessa maneira, o presente trabalho tem por objetivo aplicar a lógica ANFIS (Adaptive Neuro-Fuzzy Inference System) na estimação da rogosidade e do desgaste da ferramenta de corte no processo de retificação plana de cerâmicas avançadas. A ferramenta de corte aplicada para retificar os corpos-de-prova de alumina (96%) foi um rebolo diamantado. A partir do processamento digital dos sinais de emissão acústica e potência média de corte foram calculadas as estatísticas: média, desvio padrão, potência máxima, DPO e DPKS. As estatísticas foram aplicadas com entradas de duas redes ANFIS, uma estimando valores de rugosidade e outra estimando valores de desgaste...
The need for implementation of new equipaments in an increasingly agressive environmentl demanded a search for new products capable of withstanding high temperatures, inert to chemical corrosion and high mechanical stiffeness. Technological advances in the production of ceramic materials have become possible with the employment of manufacturing processes that previously were only employed in metals. Among the advanced ceramics machining processes, the grinding process is the most used, because of higher removal rates in constrast with the honing process and geometric limitations of lapping process. The surface reoughness is one of the output parameters of grinding process that affects, among other factors, the quality of sliding between structures that may generate heat. Moreover, the wear of the cutting tool generated during the process is associated with fixed costs and problems related to suface finishing as well as structural damages. These two variables, surface roughness and wear, have been studied by many researchers; however, the automatic control has been a difficult task to be carry out due to parameters variations occurring in the process. Hence, this work aims to apply logic ANFIS (Adaptive Neuro-Fuzzy Inference System) in the estimation of surface roughness and wear of the cutting tool in the tangential griding process of advanced ceramics. The cutting tools used to grind workpieces of alumina (96%) was a diamond grinding wheel. From the digital processing of acoustic emission and average cutting power signals some statistics were calculated: mean, standard deviation, maximum power, DPO and DPKS. The statistics were applied as inputs of two ANFIS networks estimating surface roughess and wear values. The results had demonstrated that the statistics associated with the ANFIS network can be used in the estimation of surface roughness and wear. However, the wear ANFIS network... (Complete abstract click electronic access below)

DC to DC converters stabilize the voltage obtained from voltage sources such as solar power system, wind energy sources, wave energy sources, rectified voltage from alternators, and so forth. Hence, the need for improving its control algorithm is inevitable. Many algorithms are applied to DC to DC converters. This thesis designs fuzzy adaptive dynamic programming (Fuzzy ADP) algorithm. Also, this thesis implements both adaptive dynamic programming (ADP) and Fuzzy ADP on DC to DC converters to observe the performance of the output voltage trajectories.

In recent years, response analysis of complex structures under impact loads has attracted a great deal of attention. For example, a collision or an accident that produces impact loads that exceed the design load can cause severe damage on the structural components. Although the AASHTO specification is used for impact-resistant bridge design, it has many limitations. The AASHTO specification does not incorporate complex and uncertain factors. Thus, a well-designed structure that can survive a collision under specific conditions in one region may be severely damaged if it were impacted by a different vessel, or if it were located elsewhere with different in-situ conditions. With these limitations in mind, we propose different solutions that use smart control technology to mitigate impact hazard on structures. However, it is challenging to develop an accurate mathematical model of the integrated structure-smart control systems. The reason is due to the complicated nonlinear behavior of the integrated nonlinear systems and uncertainties of high impact forces. In this context, novel algorithms are developed for identification, control and monitoring of nonlinear responses of smart structures under high impact forces. To evaluate the proposed approaches, a smart aluminum and two smart reinforced concrete beam structures were designed, manufactured, and tested in the High Impact Engineering Laboratory of Civil and Environmental Engineering at WPI. High-speed impact force and structural responses such as strain, deflection and acceleration were measured in the experimental tests. It has been demonstrated from the analytical and experimental study that: 1) the proposed system identification model predicts nonlinear behavior of smart structures under a variety of high impact forces, 2) the developed structural health monitoring algorithm is effective in identifying damage in time-varying nonlinear dynamic systems under ambient excitations, and 3) the proposed controller is effective in mitigating high impact responses of the smart structures.

This dissertation deals with, “Improvement of BLDC motor performance through intelligent controllers”. Implementation of different control strategies for Permanent Magnet Brushless DC Motor in different modes of operation is carried out through MATLAB/simulation. The controlled electric motors play a vital role in the industrial automation. It is well known that electrical motors consume a significant percentage of electrical energy and even small improvement in operating efficiency could result in large reduction in consumption of energy. Therefore new techniques are required to extract ultimate performance from these drives. There has also been tremendous research for providing suitable speed controller for PMBLDC motor. Many control strategies have been proposed in literature. The main drawback of fixed gain controllers is that their performance deteriorates as a result of changes in motor parameters & its operating conditions. In recent times hybrid controllers such as Fuzzy Logic and Adaptive neuro-fuzzy (ANFIS) have emerged as one of the most attractive non-linear controller for application in the industrial processes giving robust performance in the face of parameter variation and load disturbance effects. The main objective is to compensate for overshoots and oscillation in the response of the PMBLDC motor for wide speed range of opearation. The performance is defined in terms of accuracy, smooth operation and simplicity. The controller performance is defined in terms of rise time, Settling time, overshoot, undershoot and behavior with non-linarites. In this thesis, the PMBLDCM drive is modeled and simulated in MATLAB/SIMULINK environment. The controller such as Proportional Integral controller, Fuzzy logic controller, Adaptive- Neuro controller (ANFIS), series hybrid controller(known as Fuzzy precompensated PI controller) and self-tuning PI controller(Fuzzy tuned PI controller) are implemented for speed controller in the MATLAB/SIMULINK environment and drive performance using these controllers is observed and compared. The performance comparison is done in terms of several performance measures such as settling time, peak time, rise time, overshoot, undershoot, and load variations and stable performance under all operating conditions. iv Every controller has their own merits and demerits. It is observed that PI controller would be a good choice for simplicity and ease of application. PI controllers are observed to have no steady state error but are slow in response. The Fuzzy logic controller offer good performance in the presence of nonlinearity but Fuzzy logic controller has offset at steady state. Adaptive neuro fuzzy controller provides excellent transient response in terms of quickness of the response. Series hybrid and self- tuning PI controller offer good response in different operating conditions but main drawback is that, processing time of controllers are high.

D. Tech. Electrical Engineering.
Aims of this study is to develop a residential customers' lighting profile ANFIS-based model. This model is expected to address lighting load usage estimation in relation to the dynamic occupancy presence in a residential dwelling, which will take into account the climatic condition (natural lighting) of such an environment (e.g. South Africa) and its income. The objectives are as follows: 1. Develop an ANFIS-based residential lighting load profile model for middle income, low income and high-income earners. 2. Error reduction in residential lighting demand profile model. Performance evaluation and validation of the model using correlation and trend analysis, regression model, South Africa power utility application lighting program, non-weighted approach and comparison with other research studies (methodology).3. Reduction in / or elimination of repeated models for occupant presence and assumptions that residences are occupied at certain periods. 4. Derive meaning from complexities (behavioural trends) associated with lighting usage and extract patterns in such circumstances.

碩士
淡江大學
財務金融學系碩士班
99
Stock market prediction is important because successful prediction of stock prices may promise attractive benefits. Yet, these tasks are highly complicated and very difficult. This thesis extends the Adaptive Neuro-Fuzzy Inference System (ANFIS), to create a trading decision support system that is capable of using fuzzy reasoning combined with the pattern recognition capability of neural networks to be used in forecasting and trading the futures of Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX). This study, as a result, proposes an approach of artificial intelligence by integrating fuzzy theory with neural networks to achieve the optimization of trading rules. The result indicates that integrating fuzzy theory with neural networks has produced a trading decision support system which overcomes the physical limitations of human experts and traders in taking decisions of trading and improve the investment performance. The experimental results indicate that ANFIS can be a useful tool for economists and practitioners dealing with the forecasting of the stock index future price and increase the returns of a trader''s portfolio.

This thesis presents an investigation and a comparative study of four different approaches namely ANSI/IEEE standard models, Adaptive Neuro-Fuzzy Inference System (ANFIS), Multilayer Feedforward Neural Network (MFNN) and Elman Recurrent Neural Network (ERNN) to modeling and prediction of the top and bottom-oil temperatures for the 8 MVA Oil Air (OA)-cooled and 27 MVA Forced Air (FA)-cooled class of power transformers. The models were derived from real data of temperature measurements obtained from two industrial power installations. A comparison of the proposed techniques is presented for predicting top and bottom-oil temperatures based on the historical data measured over a 35 day period for the first transformer and 4.5 days for the second transformer with either a half or a quarter hour sampling time. Comparisons of the results obtained indicate that the hybrid neuro-fuzzy network is the best candidate for the analysis and prediction of the power transformer top and bottom-oil temperatures. The ANFIS demonstrated the best comparative performance in temperature prediction in terms of Root Mean Square Error (RMSE) and peak error.