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A boot-strap estimator for joint flux and parameters online identification for vector controlled induction motor drives

Leite, V.; Araújo, R.; Freitas, D.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.04%
This paper presents a new approach for joint rotor flux and electrical parameters on-line identification in vector controlled high-performance induction motor drives based on a boot-strap estimator that uses a reduced order extended Kalman filter for rotor flux components and rotor parameters estimation and a recursive prediction error method for stator parameters estimation. Within the prediction error method some approaches are used and compared that affect both the adaptation gain and the direction in which the updates of stator parameters are made. The induction motor model structures are described in the rotor reference frame in order to reduce the computational effort by using a higher sampling time interval.

A new online identification methodology for flux and parameters estimation of vector controlled induction motors

Leite, V.; Araújo, R.; Freitas, D.
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
46.12%
A new online identification methodology for estimation of the rotor flux components and the main electrical parameters of vector controlled induction motors is presented in this paper. The induction motor model is referred to the rotor reference frame for estimation of rotor flux and rotor parameters, and referred to the stator reference frame to estimate stator parameters. The stator parameters estimation is achieved by a prediction error method based on a model structure described by a linear regression that is independent of rotor speed and rotor parameters. The rotor flux components and rotor parameters are estimated by a reduced order extended Kalman filter, using a 4th-order state-space model structure where the state equation is described by matrices that are diagonal and independent of rotor speed as well as stator parameters. Both methods work in a boot-strap manner.

Estimação dos parâmetros genéticos do peso adulto em matrizes da raça Nelore; Genetic parameters estimation for mature weight in Nelore beef cattle

Pedrosa, Victor Breno
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/12/2006 PT
Relevância na Pesquisa
45.86%
O estudo das características produtivas visa a obtenção de animais possuidores de genótipos com potencial para altas produções mas que sejam também adaptados ao meio ambiente de criação extensiva no Brasil. Esses animais produtivos e adaptados poderiam otimizar os custos, tornando assim, sua criação sustentável em escala comercial. Apesar das características reprodutivas serem de extrema importância como objetivo de seleção, sua utilização não tem sido ampla em programas de melhoramento genético por serem consideradas de baixa herdabilidade. Entre as características produtivas existentes em bovinos de corte pode ser citada a caracterítica de peso adulto, que deve ser avaliado e monitorado o aumento do tamanho das fêmeas pela resposta indireta a seleção para peso, afim de confrontar os resultados economicamente. Dentro deste contexto foram avaliados dados de 74.547 animais com o objetivo de analisar o peso adulto e o peso adulto com repetibilidade (PAVr) em animais Nelore estimando a herdabilidade de características de desenvolvimento ponderal, utilizando modelos lineares; Estimar a correlação entre peso adulto (PAV) e características de peso ao sobreano (PS), conformação (CONF), precocidade (PREC), musculosidade (MUSC) e altura de garupa (AG); Determinar se há ou não vantagem em incluir o peso adulto em programas de seleção na raça Nelore. Os componentes de variância e de covariância foram estimados pelo método de máxima verossimilhança restrita (MTDFREML) utilizando-se o modelo animal. As estimativas dos coeficientes de herdabilidade foram de 0...

Estimador de estado e parâmetros de linha de transmissão, baseado nas equações normais; Approach for transmission line parameter and state estimation

Medrano Castillo, Madeleine Rocio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/10/2006 PT
Relevância na Pesquisa
46.06%
O processo de estimação de estado em sistemas elétricos de potência está sujeito a três tipos de erros: erros nas medidas analógicas (erros grosseiros); erros devido a informações erradas quanto aos estados de chaves e/ou disjuntores (erros topológicos) e erros causados por informações erradas de algum parâmetro do sistema (erros de parâmetros). É drástico o efeito de erros de parâmetros, para o processo de estimação de estado, normalmente intolerável, sendo, entretanto, menos evidente que os erros grosseiros e topológicos. Aproveitando o fato de que certas medidas não sofrem mudanças significativas de valor, durante um determinado intervalo de tempo, propõe-se uma metodologia para estimação de estado e parâmetros de linhas de transmissão. Na metodologia proposta, que se baseia nas equações normais, o vetor de estado convencional é aumentado para a inclusão dos parâmetros a serem estimados. Este vetor de estado aumentado é então estimado através de uma grande quantidade de medidas, obtidas em diversas amostras, durante um intervalo de tempo em que as variáveis de estado do sistema não tenham sofrido alterações significativas de valor. Esta situação ocorre tipicamente à noite, fora dos horários de pico. Propõe-se também uma metodologia para análise de observabilidade para o estimador proposto. Para comprovar a eficiência das metodologias propostas...

Uso de aproximantes de Padé na estimação de parâmetros modais em estruturas de grande porte.; Use of Padé approximants for modal parameters estimation on large scale structures.

Coelho, Luiz Antonio Barbosa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/12/2008 PT
Relevância na Pesquisa
45.88%
Este trabalho apresenta um novo algoritmo para a estimação de frequências e amortecimentos de vibrações, baseado em aproximantes de Padé, a partir da análise de sinais temporais oriundos de estruturas de grande porte. O algoritmo se baseia nas propriedades de convergência dos aproximantes de Padé, que garantem a existência de pólos que representam corretamente as componentes senoidais do sinal, e numa peculiar distribuição de pólos e zeros espúrios que decorrem da sobre-determinação do aproximante. O comportamento estatístico do algoritmo é estudado através de experimentos numéricos e sua aplicação em um caso real é feita.; This work introduces a novel estimation technique for vibration frequency and damping estimation, based on Padé approximants, and using time series taken from large structures. The algorithm is based on convergence properties of Padé approximants that assures the existence of real poles representing the sinusoidal components of the signal, and a remarkable distribution of stray poles and zeros, resulting from the approximant overdetermination. Its statistical behavior is analyzed through numerical experiments and an application for a real structure is provided as example.

Real-time estimation of transmission line impedance based on modal analysis theory

Asti, G. A.; Kurokawa, S.; Costa, E. C M; Pissolato, J.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
45.98%
The objective of this paper is to show a methodology to estimate the longitudinal parameters of transmission lines. The method is based on the modal analysis theory and developed from the currents and voltages measured at the sending and receiving ends of the line. Another proposal is to estimate the line impedance in function of the real-time load apparent power and power factor. The procedure is applied for a non-transposed 440 kV three-phase line. © 2011 IEEE.

Simplified procedure to estimate the resistance parameters of transmission lines

Kurokawa, Sérgio; Asti, Gislaine Aparecida; Costa, Eduardo Coelho Marques; Pissolato, José
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 221-227
ENG
Relevância na Pesquisa
45.95%
An alternative and simplified procedure is described to estimate the longitudinal resistances of transmission lines based on the real-time load profile. This method proposes to estimate the resistance parameters from the synchronized measurements of complex currents and complex voltages at the sending and receiving ends of transmission systems. The synchronized measurements can be in practice obtained using phasor measurement units (PMUs). © 2012 Springer-Verlag Berlin Heidelberg.

Kinetic and stoichiometric parameters estimation in a nitrifying bubble column through ‘‘in-situ’’ pulse respirometry

Ordaz, Alberto; Oliveira, Catarina S.; Aguilar, Ricardo; Carrión, Manuel; Ferreira, E. C.; Alves, M. M.; Thalasso, Frédéric
Fonte: Wiley Periodicals, Inc. Publicador: Wiley Periodicals, Inc.
Tipo: Artigo de Revista Científica
Publicado em /05/2008 ENG
Relevância na Pesquisa
45.99%
This article proposes a simple "in-situ" pulse respirometric method for the estimation of four important kinetic and stoichiometric parameters. The method is validated in a suspended biomass nitrifying reactor for the determination of (i) maximum oxygen uptake rate (OURexmax), (ii) oxidation yield (fE), (iii) biomass growth yield (fS), and (iv) affinity constant (KS). OURexmax and fE were directly obtained from respirograms. In the presented case study, a minimum substrate pulse of 10 mgNH4+-NL-1 was necessary to determine OURexmax which was 61.15 ± 4.09 mgO2 L-1 h-1 (5 repetitions). A linear correlation (r2 = 0.93) obtained between OURexmax and the biomass concentration in the reactor suggests that biomass concentration can be estimated from respirometric experiments. The substrate oxidation yield, fE, was determined along 60 days of continuous operation with an average error of 5.6%. The biomass growth yield was indirectly estimated from the substrate oxidation yield fE. The average obtained value (0.10 ± 0.04 mgCOD mg-1COD) was in accordance with the fS estimation by the traditional COD mass balance method under steady-state conditions (0.09 ± 0.01). The affinity constant KS was indirectly estimated after fitting the ascending part of the respirogram to a theoretical model. An average value of 0.48 ± 0.08 mgNH4+-NL-1 was obtained...

Parameter estimation of state space models for univariate observations

Costa, Marco; Alpuim, Teresa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.03%
This paper contributes to the problem of estimation of state space model parameters by proposing estimators for the mean, the autoregressive parameters and the noise variances which, contrarily to maximum likelihood, may be calculated without assuming any specific distribution for the errors. The estimators suggested widen the scope of the application of the generalized method of moments to some heteroscedastic models, as in the case of state-space models with varying coefficients, and give sufficient conditions for their consistency. The paper includes a simulation study comparing the proposed estimators with maximum likelihood estimators. Finally, these methods are applied to the calibration of the meteorological radar and estimation of area rainfall.

Adjustment of state space models in view of area rainfall estimation

Costa, Marco; Alpuim, Teresa
Fonte: John Wiley and Sons Publicador: John Wiley and Sons
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.06%
This paper uses state space models and the Kalman filter to merge weather radar and rain gauge measurements in order to improve area rainfall estimates. Particular attention is given to the estimation of state space model parameters because precipitation data clearly deviates from the normal distribution, and the commonly used maximum likelihood method is difficult to apply and does not perform well. This work is based on 17 storms occurring between September 1998 and November 2000 in an area including part of the Alenquer river hydrographical basin. Based on these data, the work aims to investigate the importance of the parameters estimation method to the accuracy of mean area precipitation estimates. It was possible to conclude that the distribution-free estimation methods produce, in general, better mean area rainfall estimates than the maximum likelihood. Copyright (C) 2010 John Wiley & Sons, Ltd.

Experimental results of geometric and geoacosutic parameter estimation using a vector sensor array

Santos, P.; Felisberto, P.; Jesus, S. M.; João, J.
Fonte: Encontro de Tecnologia Acustica Submarina Publicador: Encontro de Tecnologia Acustica Submarina
Tipo: Conferência ou Objeto de Conferência
Publicado em /11/2010 ENG
Relevância na Pesquisa
45.98%
The objective of this paper is to present an overview of the work developed at SiPLAB, University of Algarve, with vector sensor data collected during Makai experiment 2005, in geometric and geoacoustic parameter estimation. During this experiment devoted to high frequency initiative, acoustic data were acquired by a four element vertical vector sensor array (VSA). A vector sensor is a directional sensor constituted by one omni directional pressure sensor and three velocity-meters, where both the acoustic pressure and the three particle velocity components are measured. The spatial filtering capabilities of the vector sensors are used to estimate the direction of arrival (DOA) of low and high frequency acoustic sources considering a single and a multiple sensor VSA. An inversion method based on Bartlett estimator is used for three dimensional localization of ship’s noise where the noise source is estimated in range and depth taking into accounts the azimuth given by DOA. Moreover, this method is applied to seabed parameters estimation like sediment compressional speed, density and compressional attenuation, contributing to improve the resolution of these parameters.

Three Essays on Credit Risk Models and Their Bayesian Estimation

Kwon, Tae Yeon
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
46.19%
This dissertation consists of three essays on credit risk models and their Bayesian estimation. In each essay, defaults or default correlation models are built under one of two main streams. In our first essay, sequential estimation on hidden asset value and model parameters estimation are implemented under the Black-Cox model. To capture short-term autocorrelation in the stock market, we assume that market noise follows a mean reverting process. For estimation, two Bayesian methods are applied in this essay: the particle filter algorithm for sequential estimation of asset value and the generalized Gibbs sampling method for model parameters estimation. The first simulation study shows that sequential hidden asset value estimation using option price and equity price is more efficient and accurate than estimation using only equity price. The second simulation study shows that by applying the generalized Gibbs sampling method, model parameters can be successfully estimated under the model setting that there is no closed-form solution. In an empirical analysis using eight companies, half of which are DowJones30 companies and the other half non-Dow Jones 30 companies, the stock market noise for the firms with more liquid stock is estimated as having smaller volatility in market noise processes. In our second essay...

Induction motor parameters estimation and faults diagnosis using optimisation algorithms.

Duan, Fang
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015
Relevância na Pesquisa
56.13%
Induction motors are the most widespread rotating electric machines in industry due to their efficient and cost-effective performance. Induction motors are used to mainly operate at the constant speed since the rotor speed depends on the supply frequency. The development of power electronic devices and converter technologies has revolutionized the adjustable-speed induction motor drives. For most high-performance control methods, the effective motor control requires precise knowledge of the motor’s parameters, which are usually obtained from manufacturers. However, the manufacturers describe these parameters under starting or full-loading condition only, instead of the normal operating conditions. It is well known that motor parameters are influenced by not only the load level but also environmental factors, such as temperature, humidity and lubricant viscosity. The first part of the thesis describes the application of the sparse grid optimisation method in solving the induction motor parameter estimation problem. Kernel of the method is the efficient search in minimising the cost function on the grid created by using the Hyperbolic Cross Points (HCPs). The cost function quantifies the difference between simulation results and measurement results. Within model reference adaptive system (MRAS) framework...

Baker's yeast fermentation parameters estimation : an evolutionary approach

Leão, Celina Pinto; Costa, L.; Soares, Filomena
Fonte: APCA and IST Publicador: APCA and IST
Tipo: Conferência ou Objeto de Conferência
Publicado em 12/09/2006 ENG
Relevância na Pesquisa
45.98%
An initial understanding of the application of an evolutionary approach to baker’s yeast fermentation parameters estimation is described. This problem has a nonlinear and multimodal nature. Thus, a global optimization technique, such the evolution strategies, must be used as an approximation to the global optimum. The process is modelled by a set of differential-algebraic equations to obtain the six state variables concentration profiles, in a well-mixed reactor. The state variables profiles are obtained using parameters usually referred in literature: seven kinetic parameters and nine yield coefficients. A new problem of optimization can be formulated with the objective of minimizing the overall sum of the squared residuals that adjust the simulation results to the experimental data. With the evolutionary approach not only the parameters can be estimated but also the most significant model parameters can be identified.

Vectorial channel estimation for uplink MC-CDMA in beyond 3G wireless systems

Marques, P.; Gameiro, A. S.
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
45.91%
In beyond 3G wireless systems the bandwidth efficiency can be increased with the use of adaptive antenna arrays. This paper focus on a key issue for adaptive antenna arrays, that is, channel parameters estimation including Direction-Of-Arrival (DOA). In order to estimate DOA. the channel frequency responses for the links between the mobile users and each of base station array elements are estimated by pilot-aided minimum mean square error (MMSE) algorithm. This estimator is not sensitive to the channel statistics. Based on frequency response estimatives DOA's of impinging multipath components to the base station are estimated by a low complex Wlauimuni Likelihood (ML) approach. Furthermore an uplink burst structure with specifically designed midamble field for multiuser channel estimation in MC-CDMA is proposed. The performance is assessed in terms of channel estimation errors for a MC-CDMA TDD system over fast and slow fading mobile channels.

Fast Parameters Estimation in Medication Efficacy Assessment Model for Heart Failure Treatment

Ren, Yinzi; Fu, Xiao; Pan, Qing; Lin, Chengyu; Yang, Guiqiu; Li, Li; Gong, Shijin; Cai, Guolong; Yan, Jing; Ning, Gangmin
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.91%
Introduction. Heart failure (HF) is a common and potentially fatal condition. Cardiovascular research has focused on medical therapy for HF. Theoretical modelling could enable simulation and evaluation of the effectiveness of medications. Furthermore, the models could also help predict patients' cardiac response to the treatment which will be valuable for clinical decision-making. Methods. This study presents a fast parameters estimation algorithm for constructing a cardiovascular model for medicine evaluation. The outcome of HF treatment is assessed by hemodynamic parameters and a comprehensive index furnished by the model. Angiotensin-converting enzyme inhibitors (ACEIs) were used as a model drug in this study. Results. Our simulation results showed different treatment responses to enalapril and lisinopril, which are both ACEI drugs. A dose-effect was also observed in the model simulation. Conclusions. Our results agreed well with the findings from clinical trials and previous literature, suggesting the validity of the model.

Efficient Rotation-Scaling-Translation Parameters Estimation Based on Fractal Image Model

Uss, M.; Vozel, B.; Lukin, V.; Chehdi, K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.03%
This paper deals with area-based subpixel image registration under rotation-isometric scaling-translation transformation hypothesis. Our approach is based on a parametrical modeling of geometrically transformed textural image fragments and maximum likelihood estimation of transformation vector between them. Due to the parametrical approach based on the fractional Brownian motion modeling of the local fragments texture, the proposed estimator MLfBm (ML stands for "Maximum Likelihood" and fBm for "Fractal Brownian motion") has the ability to better adapt to real image texture content compared to other methods relying on universal similarity measures like mutual information or normalized correlation. The main benefits are observed when assumptions underlying the fBm model are fully satisfied, e.g. for isotropic normally distributed textures with stationary increments. Experiments on both simulated and real images and for high and weak correlation between registered images show that the MLfBm estimator offers significant improvement compared to other state-of-the-art methods. It reduces translation vector, rotation angle and scaling factor estimation errors by a factor of about 1.75...2 and it decreases probability of false match by up to 5 times. Besides...

Sensitivity analysis and non linear parameters estimation of porous materials from normal sound coefficient absorption measurements

Garoum, M.; Idchabani, R.; Tajayouti, M.; Rhachi, M.; Moreno, Antonio
Fonte: Société française d'acoustique; Acoustical Society of America; European Acoustics Association Publicador: Société française d'acoustique; Acoustical Society of America; European Acoustics Association
Tipo: Comunicación de congreso Formato: 29167 bytes; application/pdf
ENG
Relevância na Pesquisa
46.15%
Communication presented at: Acoustics '08 (Paris, France, June 29-July 4, 2008), comprising: 5th Forum Acusticum, 155th ASA Meeting, 9e Congrès Français d'Acoustique, 7th European Conference on Noise Control (Euronoise), 9th European Conference on Underwater Acoustics (ECUA).-- Book of abstracts published in Vol. 94 Suppl.1: S1-S1020 (May/June 2008) of Acta Acustica united with Acustica: The Journal of the European Acoustics Association (ISSN 1610-1928).; In literature, various models have been proposed in order to predict characteristic impedance Zc and wave number kc of porous materials. To use these models their involved nonacoustical parameters (i. e. flow resistivity, tortuosity porosityoe) are usually measured. Unfortunately measurements require specialised equipments and are often difficult on loose porous materials leading most often to erroneous values. Moreover, the inverse estimation of theses parameters from experimental data is not an easy task as believed. This is due to the non linearity of models and the presence of some parameters with weak and/or linearly dependent influences. In this work an approach based on the tradeoff between magnitude and linear independence of the sensitivity matrix components is presented in order to achieve an efficient ranking of parameters according to their inherent ease of estimation. Next this approach is associated to Genetic Algorithms to minimize the least squares norm between measured and modelled normal sound absorption coefficient. For five widely used models in literatures...

ESTIMATION OF BALLISTIC PARAMETERS OF GUN PROPELLANTS THROUGH CLOSED VESSEL EXPERIMENT MODELING

de Oliveira, J. L. S. P.; Filho, A. A. M. F.; Platt, G. M.; Peixoto, F. C.
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Peer-reviewed Article Formato: application/pdf
Publicado em 31/08/2005 ENG
Relevância na Pesquisa
46%
Closed vessels have being used for the regression of lumped ballistic parameters for decades. However, if material and energy balances are coupled with burning rate empirical correlations, several uncorrelated parameters can be estimated, which describe more accurately the thermochemical behavior of the gases generated, even if the chemical composition of the propellant is unknown (as when the propellant is aged, for instance). This research presents such approach leading to a system of differential equations which are integrated to produce a theoretical pressure profile in the vessel, highly dependent on the choice of empirical parameters. Such parameters are manipulated according to the Maximum Likelihood statistical procedure, which leads to the best set of parameters to describe the propellant.

Estimation of Forest Stands Biophysical Parameters Using LANDSAT TM Images of Pinus pinaster Stands in Northern Portugal

Lopes,Domingos
Fonte: Unidade de Silvicultura e Produtos Florestais Publicador: Unidade de Silvicultura e Produtos Florestais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
46.06%
Investigation on remote imagery accuracy for forest stands biophysical parameters estimation has been increasing in the last decades. In order to analyse how Landsat TM images and derived vegetation indices could be used to estimate Pinus pinaster stands biophysical parameters, 42 sampling plots were established in August 1997 in order to obtain leaf area index (LAI) field estimates, dendrometric stands characteristics (e.g. diameter at breast height, tree's volume) and spectrometric radiometric data. Sampling plots location was mapped using a GPS. After fieldwork, a Landsat TM image was submitted to pre-processing techniques (radiometric, atmospheric and geometric correction) and vegetation indices were calculated. Several regression equations were adjusted in order to create mathematical models to estimate biophysical parameters, using the better-correlated vegetation indices as independent variables. The results demonstrated that Pinus pinaster stands biophysical parameters could be estimated by means of vegetation indices derived from Landsat TM images, being the best results achieved for site index, diameter at breast height and mean and dominant height.