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Wyszukujesz frazę "aproksymacja" wg kryterium: Temat


Tytuł:
A proximal-based algorithm for piecewise sparse approximation with application to scattered data fitting
Autorzy:
Zhong, Yijun
Li, Chongjun
Li, Zhong
Duan, Xiaojuan
Powiązania:
https://bibliotekanauki.pl/articles/2172132.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
piecewise sparse approximation
proximal gradient
scattered data fitting
aproksymacja rzadka
gradient proksymalny
dopasowanie danych
Opis:
In some applications, there are signals with a piecewise structure to be recovered. In this paper, we propose a piecewise sparse approximation model and a piecewise proximal gradient method (JPGA) which aim to approximate piecewise signals. We also make an analysis of the JPGA based on differential equations, which provides another perspective on the convergence rate of the JPGA. In addition, we show that the problem of sparse representation of the fitting surface to the given scattered data can be considered as a piecewise sparse approximation. Numerical experimental results show that the JPGA can not only effectively fit the surface, but also protect the piecewise sparsity of the representation coefficient.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2022, 32, 4; 671--682
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Approximation of Jacobian inverse kinematics algorithms
Autorzy:
Tchoń, K.
Karpińska, J.
Janiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/929992.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
kinematyka odwrotna
pseudoodwrotny Jacobian
aproksymacja
robot inverse kinematics
extended Jacobian
Jacobian pseudoinverse
approximation
Opis:
This paper addresses the synthesis problem of Jacobian inverse kinematics algorithms for stationary manipulators and mobile robots. Special attention is paid to the design of extended Jacobian algorithms that approximate the Jacobian pseudoinverse algorithm. Two approaches to the approximation problem are developed: one relies on variational calculus, the other is differential geometric. Example designs of the extended Jacobian inverse kinematics algorithm for 3DOF manipulators as well as for the unicycle mobile robot illustrate the theoretical concepts.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 4; 519-531
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stochastic Neural Networks for Feasibility Checking
Autorzy:
Strausz, G.
Powiązania:
https://bibliotekanauki.pl/articles/908272.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja
sieć neuronowa
aproksymacja
optimization
neural networks
simulated annealing
mean-field approximation
Opis:
Complex diagnosis problems, defined by high-level models, often lead to constraint-based discrete optimization tasks. A logical description of large, complex systems usually contains numerous variables. The first test of the logical description is typically to check the feasibility in order to know that there is no contradiction in the model. This can be formulated as an optimization problem and methods of discrete optimization theory can then be used. The purpose of the paper is to show that stochastic neural networks can be applied to this type of tasks and the networks are efficient tools for finding feasible or good-quality configurations. Boltzmann and mean-field neural networks were tested on large-sized complex problems.The paper presents simulation results obtained from a real application task and compares the performance of the neural networks being examined.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 4; 921-937
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Water wave scattering by an infinite step in the presence of an ice-cover
Autorzy:
Ray, S.
De, S.
Mandal, B. N.
Powiązania:
https://bibliotekanauki.pl/articles/265982.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fala wodna
pokrywa lodowa
aproksymacja Galerkina
water wave scattering
ice cover
infinite step
integral equation
Galerkin approximation
reflection and transmission coefficients
Opis:
The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finie and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absencje of ice-cover, the results for the free surface are recovered.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 157-168
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recognition of atherosclerotic plaques and their extended dimensioning with computerized tomography angiography imaging
Autorzy:
Markiewicz, T.
Dziekiewicz, M.
Maruszyński, M.
Bogusławska-Walecka, R.
Kozłowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/330374.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
computed tomography
atherosclerotic plaque
image processing
approximation
tomografia komputerowa
blaszka miażdżycowa
przetwarzanie obrazu
aproksymacja
Opis:
In this paper the authors raise the issue of automatic discrimination of atherosclerotic plaques within an artery lumen based on numerical and statistical thresholding of Computerized Tomography Angiographic (CTA) images and their advanced dimensioning as a support for preoperative vessel assessment. For the study, a set of tomograms of the aorta, as well as the ilio-femoral and femoral arteries were examined. In each case a sequence of about 130–480 images of the artery cutoff planes were analyzed prior to their segmentation based on morphological image transformation. A crucial step in the staging of atherosclerotic alteration is recognition of the plaque in the CTA image. To solve this problem, statistical and linear fitting methods, including the least-squares approximation by polynomial and spline polynomial functions, as well as the error fitting function were used. Also, new descriptors of atherosclerotic changes, such as the lumen decrease factor, the circumference occupancy factor, and the convex plaque area factor, are proposed as a means of facilitating preoperative vessel examination. Finally, ways to reduce the computational time are discussed. The proposed methods can be very useful for automatic quantification of atherosclerotic changes visualized by CTA imaging.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2014, 24, 1; 33-47
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On-line parameter and delay estimation of continuous-time dynamic systems
Autorzy:
Kozłowski, J.
Kowalczuk, Z.
Powiązania:
https://bibliotekanauki.pl/articles/330669.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
delay system
continuous time model
discrete approximation
parameter estimation
least squares estimator
instrumental variable estimator
układ z opóźnieniem
aproksymacja dyskretna
estymacja parametrów
zmienna instrumentalna
Opis:
The problem of on-line identification of non-stationary delay systems is considered. The dynamics of supervised industrial processes are usually modeled by ordinary differential equations. Discrete-time mechanizations of continuous-time process models are implemented with the use of dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures mechanized in recursive forms are applied for simultaneous identification of input delay and spectral parameters of the system models. The performance of the proposed estimation algorithms is verified in an illustrative numerical simulation study.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2015, 25, 2; 223-232
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Approximation of fractional positive stable continuous-time linear systems by fractional positive stable discrete-time systems
Autorzy:
Kaczorek, T.
Powiązania:
https://bibliotekanauki.pl/articles/330801.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
Pade approximation
fractional system
linear positive system
aproksymacja Padégo
układ ułamkowy
układ liniowy dodatni
Opis:
Fractional positive asymptotically stable continuous-time linear systems are approximated by fractional positive asymptotically stable discrete-time systems using a linear Padé-type approximation. It is shown that the approximation preserves the positivity and asymptotic stability of the systems. An optional system approximation is also discussed.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2013, 23, 3; 501-506
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite horizon nonlinear predictive control by the Taylor approximation: Application to robot tracking trajectory
Autorzy:
Hedjar, R.
Toumi, R.
Boucher, P.
Dumur, D.
Powiązania:
https://bibliotekanauki.pl/articles/908454.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
układ nieliniowy
układ ciągły
sterowanie predykcyjne
aproksymacja Taylora
śledzenie trajektorii
nonlinear continuous time predictive control
Taylor approximation
tracking trajectory and robot
Opis:
In industrial control systems, practical interest is driven by the fact that today’s processes need to be operated under tighter performance specifications. Often these demands can only be met when process nonlinearities are explicitly considered in the controller. Nonlinear predictive control, the extension of well-established linear predictive control to nonlinear systems, appears to be a well-suited approach for this kind of problems. In this paper, an optimal nonlinear predictive control structure, which provides asymptotic tracking of smooth reference trajectories, is presented. The controller is based on a finite–horizon continuous time minimization of nonlinear predicted tracking errors. A key feature of the control law is that its implementation does not need to perform on-line optimization, and asymptotic tracking of smooth reference signal is guaranteed. An integral action is used to increase the robustness of the closed-loop system with respect to uncertainties and parameters variations. The proposed control scheme is first applied to planning motions problem of a mobile robot and, afterwards, to the trajectory tracking problem of a rigid link manipulator. Simulation results are performed to validate the tracking performance of the proposed controller.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2005, 15, 4; 527-540
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determining the weights of a Fourier series neural network on the basis of the multidimensional discrete Fourier transform
Autorzy:
Halawa, K.
Powiązania:
https://bibliotekanauki.pl/articles/907904.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sieć neuronowa ortogonalna
szereg Fouriera
transformata Fouriera
aproksymacja
system nieliniowy
orthogonal neural networks
Fourier series
fast Fourier transform
approximation
nonlinear system
Opis:
This paper presents a method for training a Fourier series neural network on the basis of the multidimensional discrete Fourier transform. The proposed method is characterized by low computational complexity. The article shows how the method can be used for modelling dynamic systems.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2008, 18, 3; 369-375
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Iterative Construction and Optimization of Fuzzy Models
Autorzy:
Golea, N.
Benmahammed, K.
Powiązania:
https://bibliotekanauki.pl/articles/908273.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
aproksymacja rozmyta
optymalizacja iteracyjna
fuzzy approximation
decoupled learning
iterative optimization
Opis:
In this paper, a constructive approach to the fuzzy model selection problem is developed. First, the selection of membership functions is decoupled from parameter calculations using an orthogonalization procedure. Since each membership function depends only on its own parameters, the selection of rules is performed in a sequential manner. At each learning step, a new membership function is created and its parameters are optimized. The resulting parameter calculation boils down to the solution of a triangular system. This approach reduces significantly the computational complexity, and allows for the derivation of a simple optimization algorithm. In addition, optimization of the membership functions is related to the approximation accuracy. Simulation results, when compared with the orthogonal least-squares algorithm, show that this approach is less sensitive to the size of the training data and converges rapidly.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 4; 899-919
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinematic Approximation of Robotic Manipulators
Autorzy:
Dulęba, I.
Powiązania:
https://bibliotekanauki.pl/articles/911220.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
manipulator
kinematyka
aproksymacja
kinematics
approximation
metrics
ULB robot
Opis:
A kinematic approximation of the nominal, reference kinematics of a manipulator is addressed. The approximation task leads to a minimax optimization problem. Some modifications facilitating the implementation of the algorithm in search spaces of high dimensionalities are presented. A sub-gradient mesh algorithm of solving the minimax task is given in detail. The approximation of the CYBOTECH manipulator with a ULB robot is provided based on the use of the Chebyshev metric. As an alternative, some measures of proximity of manipulators are also introduced.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2000, 10, 3; 605-622
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oblique water wave diffraction by a step
Autorzy:
Dolai, P.
Powiązania:
https://bibliotekanauki.pl/articles/264885.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
finite step
Havelock expansion
Galerkin approximation
Gegenbauer polynomial
reflection and transmission coefficients
aproksymacja Galerkina
wielomian Gegenbauera
odbicie
Opis:
This paper is concerned with the problem of diffraction of an obliquely incident surface water wave train on an obstacle in the form of a finite step. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultraspherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for reflection and transmission coefficients which are depicted graphically. From these figures various interesting results are discussed.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 1; 35-47
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of oblique water waves by an infinite step
Autorzy:
Dolai, P.
Dolai, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/265749.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
aproksymacja Galerkina
wielomian Gegenbauera
współczynnik transmisji
infinite step
Havelock expansion
Galerkin approximation
Gegenbauer polynomial
reflection and transmission coefficients
Opis:
The present paper is concerned with the problem of scattering of obliquely incident surface water wave train passing over a step bottom between the regions of finite and infinite depth. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain very accurate numerical estimates for reflection and transmission coefficients. The numerical results are illustrated in tables.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 327-338
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal approximation, simulation and analog realization of the fundamental fractional order transfer function
Autorzy:
Djouambi, A.
Charef, A.
Besançon, A. V.
Powiązania:
https://bibliotekanauki.pl/articles/929796.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
system ułamkowy
aproksymacja
funkcja przenoszenia
fractional systems
approximation
simulation and distribution of the relaxation times function
Opis:
This paper provides an optimal approximation of the fundamental linear fractional order transfer function using a distribution of the relaxation time function. Simple methods, useful in systems and control theories, which can be used to approximate the irrational transfer function of a class of fractional systems for a given frequency band by a rational function are presented. The optimal parameters of the approximated model are obtained by minimizing simultaneously the gain and the phase error between the irrational transfer function and its rational approximation. A simple analog circuit which can serve as a fundamental analog fractional system is obtained. Illustrative examples are presented to show the quality and usefulness of the approximation method.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2007, 17, 4; 455-462
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Approximation of Large-Scale Dynamical Systems: an Overview
Autorzy:
Antoulas, A. C.
Sorensen, D. C.
Powiązania:
https://bibliotekanauki.pl/articles/908058.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
aproksymacja
system dynamiczny
model reduction
SVD
Hankel
balancing
Krylov
Opis:
In this paper we review the state of affairs in the area of approximation of large-scale systems. We distinguish three basic categories, namely the {SVD}-based, the {Krylov}-based and the {SVD-Krylov}-based approximation methods. The first two were developed independently of each other and have distinct sets of attributes and drawbacks. The third approach seeks to combine the best attributes of the first two.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2001, 11, 5; 1093-1121
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł

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