Search results for "Estimation theory"

Parameter identification of induction motor model using genetic algorithms

1998

The paper deals with methods of identification of the parameters of an induction motor model using genetic algorithms. It is supposed that the inverter supplying the motor is directly accessible for control of the conduction sequences of its power switches. This makes it possible to carry out a test consisting of a transient from standstill to steady-state operation at a given frequency and successive free motion to standstill. During this test, data are acquired referring to stator voltages, and currents and speed. Then, a genetic algorithm is employed with the aim of determining the mechanical and electrical parameters of the model, so as to reproduce the input-output behaviour of a real …

GA-based Off-Line Parameter Estimation of the Induction Motor Model Including Magnetic Saturation and Iron Losses

2020

This paper, starting from recent papers in the scientific literature dealing with Rotating Induction Motor (RIM) dynamic modelling, as a first step, improves its space-vector dynamic model, including both the magnetic saturation and iron losses; The main original aspects of the proposed model are the following: 1) the magnetic saturation of the iron core has been described on the basis of both current versus flux and flux versus current functions, 3) it includes the iron losses, separating them in hysteresis and eddy current ones, 4) it includes the effect of the load on the magnetic saturation. Afterwards, it proposes an off-line technique for the estimation of electrical parameters of thi…

Improving the dynamic behavior and working accuracy of the CNC laser cutting machines

2012

CNC laser cutting machines are widely encountered in the manufacturing workshops. The dynamic behavior and working accuracy of these machines decreases in time, due to normal wear and intensive use. Consequently, a process or re-tuning the control parameters is required and it has to be performed at the workshop level. The paperwork presents a joint simulation and experimental process for improving the accuracy of CNC laser cutting machines. The approach is focused on the capability of the machine to cut rectangular corners.

A FAST PROCEDURE TO ESTIMATE HYDRAULIC CHARACTERISTICS OF GREENHOUSE SUBSTRATES FROM ONE-STEP OUTFLOW DATA

2011

Multiresolution wavelet-based approach to identification of modal parameters of a vehicle full-scale crash test

2012

In this work estimation of vehicle modal parameters was achieved by application of a wavelet-based method. The time-frequency analysis, which comprises those techniques that study a signal in both the time and frequency domains simultaneously, using Morlet wavelet properties are applied to the measured acceleration pulse of the colliding vehicle. Determination of the ridge of the wavelet coefficients matrix makes it possible to identify the frequency components of the recorded crash pulse. Subsequently, by using the estimated natural frequency of the system, the values of damping factor for a given mode shape are assessed. In this work there are concerned both: the major frequencies of the …

Uncertainty related to climate change in the assessment of the DDF curve parameters

2017

In the context of climate change, the evaluation of the parameters of Depth-Duration-Frequency (DDF) curves has become a critical issue. Neglecting future rainfall variations could result in an overestimation/underestimation of DDF parameters and, consequently, of the design storm. In this study, uncertainty analysis was integrated into trend analysis to provide an estimate of trends that cannot actually be rigorously verified. A Bayesian procedure was suggested for the updating of DDF curve parameters and to evaluate the uncertainty related to their assessment. The proposed procedure also allowed identification of the years of a series that contributed most to the overall uncertainty relat…

Orthogonal Multicarrier Transmission with Modal Channel Estimation

2009

A novel multi-carrier orthogonal transmission scheme is presented. While being simpler to implement, it has a spectral efficiency and design parameters similar to those of Orthogonal Frequency Division Multiplexing based on Offset Quadrature Amplitude Modulation (OFDM/OQAM). A parametric channel estimation technique is subsequently reported. The proposed technique is based on an algorithm obtained from classic Multiple Signal Classification (MUSIC) by relaxation of the hypothesis on the number of measurements with respect to the number of sensors. Numerical simulations show that our proposal outperforms previous works in this field.

Block Bootstrap Methods and the Choice of Stocks for the Long Run

2011

Financial advisors commonly recommend that the investment horizon should be rather long in order to benefit from the "time diversification". In this case, in order to choose the optimal portfolio, it is necessary to estimate the risk and reward of several alternative portfolios over a long-run given a sample of observations over a short-run. Two interrelated obstacles in these estimations are lack of sufficient data and the uncertainty in the nature of the return generating process. To overcome these obstacles researchers rely heavily on block bootstrap methods. In this paper we demonstrate that the estimates provided by a block bootstrap method are generally biased and we propose two metho…

Kernel image similarity criterion

2011

This paper presents a family of metrics for assessing image similarity. The methods use the Hilbert-Schmidt Independence Criterion (HSIC) to estimate nonlinear statistical dependence between multidimensional images. The proposed methods have very good theoretical and practical properties. We illustrate the performance in evaluating the quality of natural photographic images, hyperspectral images under different noise levels, in synthetic multiresolution problems, and real pansharpening products.

Parameter estimation: an advanced simulation tool in biomedicine

1990

Parameter estimation as an advanced tool in biomedicine have become extremely important in the study of biological systems. With increasing physiological knowledge and more efficient computers, modelling, simulation, and estimation have grown during the past 20 years to one of the most powerful tools of biomedical system analysis. Moreover modelling, simulation and estimation is of growing importance for determination of non-measurable parameters and state variables of biomedical systems as well as for case studies research of biomedical processes, which have been developed by physicians and system engineers and have also been widely accepted by biomedical scientists. These models already d…