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Wyświetlanie 1-15 z 55
Tytuł:
On the Solution of a Finite Element Approximation of a Linear Obstacle Plate Problem
Autorzy:
Fernandes, L. M.
Figueiredo, I. N.
Judice, J. J.
Powiązania:
https://bibliotekanauki.pl/articles/907894.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
variational inequality
complementarity problem
contact problem
Opis:
In this paper the solution of a finite element approximation of a linear obstacle plate problem is investigated. A simple version of an interior point method and a block pivoting algorithm have been proposed for the solution of this problem. Special purpose implementations of these procedures are included and have been used in the solution of a set of test problems. The results of these experiences indicate that these procedures are quite efficient to deal with these instances and compare favourably with the path-following PATH and the active-set MINOS codes of the commercial GAMS collection
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 27-40
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A relation of dominance for the bicriterion bus routing problem
Autorzy:
Widuch, J.
Powiązania:
https://bibliotekanauki.pl/articles/330092.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
multicriteria optimization
set of nondominated solutions
bicriterion shortest path problem
variable weights
label correcting algorithm
transportation problem
optymalizacja wielokryterialna
zbiór rozwiązań niezdominowanych
dwukryterialny problem najkrótszej ścieżki
zmienne wagi
problem transportowy
Opis:
A bicriterion bus routing (BBR) problem is described and analysed. The objective is to find a route from the start stop to the final stop minimizing the time and the cost of travel simultaneously. Additionally, the time of starting travel at the start stop is given. The BBR problem can be resolved using methods of graph theory. It comes down to resolving a bicriterion shortest path (BSP) problem in a multigraph with variable weights. In the paper, differences between the problem with constant weights and that with variable weights are described and analysed, with particular emphasis on properties satisfied only for the problem with variable weights and the description of the influence of dominated partial solutions on non-dominated final solutions. This paper proposes methods of estimation a dominated partial solution for the possibility of obtaining a non-dominated final solution from it. An algorithm for solving the BBR problem implementing these estimation methods is proposed and the results of experimental tests are presented.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 1; 133-155
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A single image deblurring approach based on a fractional order dark channel prior
Autorzy:
Yu, Xiaoyuan
Xie, Wei
Yu, Jinwei
Powiązania:
https://bibliotekanauki.pl/articles/2172119.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
blind image deblurring
fractional order dark channel prior
nonconvex problem
obraz rozmyty
rząd ułamkowy
problem niewypukły
Opis:
The dark channel prior has been successfully applied to solve the blind deblurring problem on different scene images. Since the dark channel of the blurry-noise image is similar to that of the corresponding clear image, the sparsity of the dark channel is less effective for image blind deblurring. Inspired by the fact that a fractional order calculation can inhibit the noise and preserve the texture information of the image, a fractional order dark channel prior is proposed for image deblurring in this paper. It is appropriate for kernel estimation where input images and intermediate images are processed by using a fractional order dark channel prior. Furthermore, the non-convex problem is solved by the half-quadratic splitting method, and some metrics are used for deblurring image quality assessment. Finally, quantitative and qualitative experimental results show that the proposed method achieves state-of-the-art results on synthetic and real blurry images.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2022, 32, 3; 441--454
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unilateral Contact Applications Using Fem Software
Autorzy:
Stavroulaki, M. E.
Stavroulakis, G. E.
Powiązania:
https://bibliotekanauki.pl/articles/907898.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
nonsmooth analysis
constrained optimization
contact problem
Opis:
Nonsmooth analysis, inequality constrained optimization and variational inequalities are involved in the modelling of unilateral contact problems. The corresponding theoretical and algorithmic tools, which are part of the area known as nonsmooth mechanics, are by no means classical. In general purpose software some of these tools (perhaps in a simplified way) are currently available. Two engineering applications, a rubber-coated roller contact problem and a masonry wall, solved with MARC, are briefly presented, together with elements of the underlying theory.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 115-125
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solving SAT in a distributed cloud: A portfolio approach
Autorzy:
Ngoko, Yanik
Cérin, Christophe
Trystram, Denis
Powiązania:
https://bibliotekanauki.pl/articles/329749.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
resource provisioning
resource scheduling
parallel distributed SAT
algorithm portfolio
maximum coverage problem
udostępnianie zasobów
szeregowanie zasobów
problem maksymalnego zasięgu
Opis:
We introduce a new parallel and distributed algorithm for the solution of the satisfiability problem. It is based on an algorithm portfolio and is intended to be used for servicing requests in a distributed cloud. The core of our contribution is the modeling of the optimal resource sharing schedule in parallel executions and the proposition of heuristics for its approximation. For this purpose, we reformulate a computational problem introduced in a prior work. The main assumption is that it is possible to learn optimal resource sharing from traces collected on past executions on a representative set of instances. We show that the learning can be formalized as a set coverage problem. Then we propose to solve it by approximation and dynamic programming algorithms based on classical greedy algorithms for the maximum coverage problem. Finally, we conduct an experimental evaluation for comparing the performance of the various algorithms proposed. The results show that some algorithms become more competitive if we intend to determine the trade-off between their quality and the runtime required for their computation.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2019, 29, 2; 261-274
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Increasing pursuer capturability by using hybrid dynamics
Autorzy:
Glizer, V. Y.
Turetsky, V.
Powiązania:
https://bibliotekanauki.pl/articles/331434.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
interception problem
hybrid interceptor's dynamics
robust capture zone
Opis:
A robust interception of a maneuverable target (evader) by an interceptor (pursuer) with hybrid dynamics is considered. The controls of the pursuer and the evader are bounded. The duration of the engagement is prescribed. The pursuer has two possible dynamic modes, which can be switched once during the engagement, while the dynamics of the evader are fixed. The case where for both dynamic modes there exists an unbounded capture zone was analyzed in our previous work. The conditions under which the pursuer can increase its capturability by utilizing the hybrid dynamics were established and the new robust capture zone was constructed. In the present paper, we extend this result to the cases where at least for one dynamic mode of the pursuer the capture zone is bounded. For these instances, conditions of increasing the pursuer’s hybrid capturability are derived. Respective capture zones are constructed. Illustrative examples and results of extensive simulation for a realistic non-linear engagement model in the presence of a random wind are given.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2015, 25, 1; 77-92
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability Analysis of Solutions to an Optimal Control Problem Associated With a Goursat-Darboux Problem
Autorzy:
Idczak, D.
Majewski, M.
Walczak, S.
Powiązania:
https://bibliotekanauki.pl/articles/908253.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
Goursat-Darboux problem
optimal control
continous dependence
Opis:
In the present paper, some results concerning the continuous dependence of optimal solutions and optimal values on data for an optimal control problem associated with a Goursat-Darboux problem and an integral cost functional are derived.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2003, 13, 1; 29-44
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A factor graph based genetic algorithm
Autorzy:
Helmi, B. H.
Rahmani, A. T.
Pelikan, M.
Powiązania:
https://bibliotekanauki.pl/articles/330811.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optimization problem
genetic algorithm
estimation
distribution algorithm
factor graph
matrix factorization
problem optymalizacji
algorytm genetyczny
algorytm estymacji rozkładu
faktoryzacja macierzy
Opis:
We propose a new linkage learning genetic algorithm called the Factor Graph based Genetic Algorithm (FGGA). In the FGGA, a factor graph is used to encode the underlying dependencies between variables of the problem. In order to learn the factor graph from a population of potential solutions, a symmetric non-negative matrix factorization is employed to factorize the matrix of pair-wise dependencies. To show the performance of the FGGA, encouraging experimental results on different separable problems are provided as support for the mathematical analysis of the approach. The experiments show that FGGA is capable of learning linkages and solving the optimization problems in polynomial time with a polynomial number of evaluations.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2014, 24, 3; 621-633
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of a Viscoelastic Antiplane Contact Problem With Slip-Dependent Friction
Autorzy:
Hoarau-Mantel, T. V.
Matei, A.
Powiązania:
https://bibliotekanauki.pl/articles/907889.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
informatyka
antiplane problem
slip-dependent friciotn law
viscoelastic law
Opis:
We study a mathematical problem modelling the antiplane shear deformation of a viscoelastic body in frictional contact with a rigid foundation. The contact is bilateral and is modelled with a slip-dependent friction law. We present the classical formulation for the antiplane problem and write the corresponding variational formulation. Then we establish the existence of a unique weak solution to the model, by using the Banach fixed-point theorem and classical results for elliptic variational inequalities. Finally, we prove that the solution converges to the solution of the corresponding elastic problem as the viscosity converges to zero.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 51-58
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A sign preserving mixed finite element approximation for contact problems
Autorzy:
Hild, P.
Powiązania:
https://bibliotekanauki.pl/articles/907565.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
nierówność wariacyjna
zagadnienie kontaktowe
metoda elementów skończonych
variational inequality
positive operator
averaging operator
contact problem
Signorini problem
mixed finite element method
Opis:
This paper is concerned with the frictionless unilateral contact problem (i.e., a Signorini problem with the elasticity operator). We consider a mixed finite element method in which the unknowns are the displacement field and the contact pressure. The particularity of the method is that it furnishes a normal displacement field and a contact pressure satisfying the sign conditions of the continuous problem. The a priori error analysis of the method is closely linked with the study of a specific positivity preserving operator of averaging type which differs from the one of Chen and Nochetto. We show that this method is convergent and satisfies the same a priori error estimates as the standard approach in which the approximated contact pressure satisfies only a weak sign condition. Finally we perform some computations to illustrate and compare the sign preserving method with the standard approach.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 3; 487-498
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A metaheuristic for a numerical approximation to the mass transfer problem
Autorzy:
Avendaño-Garrido, M. L.
Gabriel-Argüelles, J. R.
Quintana-Torres, L.
Mezura-Montes, E.
Powiązania:
https://bibliotekanauki.pl/articles/329972.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
Monge–Kantorovich mass transfer problem
finite dimensional linear programming
transport problem
metaheuristic algorithm
scatter search
programowanie skończenie wymiarowe
zadanie transportowe
algorytm metaheurystyczny
Opis:
This work presents an improvement of the approximation scheme for the Monge–Kantorovich (MK) mass transfer problem on compact spaces, which is studied by Gabriel et al. (2010), whose scheme discretizes the MK problem, reduced to solve a sequence of finite transport problems. The improvement presented in this work uses a metaheuristic algorithm inspired by scatter search in order to reduce the dimensionality of each transport problem. The new scheme solves a sequence of linear programming problems similar to the transport ones but with a lower dimension. The proposed metaheuristic is supported by a convergence theorem. Finally, examples with an exact solution are used to illustrate the performance of our proposal.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 4; 757-766
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected multicriteria shortest path problems: An analysis of complexity, models and adaptation of standard algorithms
Autorzy:
Tarapata, Z.
Powiązania:
https://bibliotekanauki.pl/articles/929638.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
problem najkrótszej ścieżki
złożoność algorytmu
algorytm aproksymacji
multiobjective shortest path
stochastic shortest path
algorithm complexity
routing problem
terrain-based modeling
approximation algorithm
Opis:
The paper presents selected multicriteria (multiobjective) approaches to shortest path problems. A classification of multiobjective shortest path (MOSP) problems is given. Different models of MOSP problems are discussed in detail. Methods of solving the formulated optimization problems are presented. An analysis of the complexity of the presented methods and ways of adapting of classical algorithms for solving multiobjective shortest path problems are described. A comparison of the effectiveness of solving selected MOSP problems defined as mathematical programming problems (using the CPLEX 7.0 solver) and multi-weighted graph problems (using modified Dijkstra’s algorithm) is given. Experimental results of using the presented methods for multicriteria path selection in a terrain-based grid network are given.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2007, 17, 2; 269-287
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Granular Derivatives and the Solution of a Granular Initial Value Problem
Autorzy:
Batyrshin, I.
Powiązania:
https://bibliotekanauki.pl/articles/908040.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
informatyka
fuzzy differential
fuzzy granule
initial value problem
cylindrical extension
Opis:
Perceptions about function changes are represented by rules like "If X is SMALL then Y is QUICKLY INCREASING." The consequent part of a rule describes a granule of directions of the function change when X is increasing on the fuzzy interval given in the antecedent part of the rule. Each rule defines a granular differential and a rule base defines a granular derivative. A reconstruction of a fuzzy function given by the granular derivative and the initial value given by the rule is similar to Euler's piecewise linear solution of an initial value problem. The solution method is based on a granulation of the directions of the function change, on an extension of the initial value in directions and on a propagation of fuzzy constraints given in antecedent parts of rules on possible function values. The proposed method is illustrated with an example.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 3; 403-410
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topology optimization of quasistatic contact problems
Autorzy:
Myśliński, A.
Powiązania:
https://bibliotekanauki.pl/articles/331424.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
elastyczność
optymalizacja topologiczna
quasistatic contact problem
elasticity
Tresca friction
topology optimization
Opis:
This paper deals with the formulation of a necessary optimality condition for a topology optimization problem for an elastic contact problem with Tresca friction. In the paper a quasistatic contact model is considered, rather than a stationary one used in the literature. The functional approximating the normal contact stress is chosen as the shape functional. The aim of the topology optimization problem considered is to find the optimal material distribution inside a design domain occupied by the body in unilateral contact with the rigid foundation to obtain the optimally shaped domain for which the normal contact stress along the contact boundary is minimized. The volume of the body is assumed to be bounded. Using the material derivative and asymptotic expansion methods as well as the results concerning the differentiability of solutions to quasistatic variational inequalities, the topological derivative of the shape functional is calculated and a necessary optimality condition is formulated.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2012, 22, 2; 269-280
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accurate gradient computations at interfaces using finite element methods
Autorzy:
Qin, F.
Wang, Z.
Ma, Z.
Li, Z.
Powiązania:
https://bibliotekanauki.pl/articles/330659.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
elliptic interface problem
gradient flux computation
IFEM
mixed FE formulation
computational tube
Opis:
New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is to get not only an accurate solution, but also an accurate first order derivative at the interface (from each side). The key in 1D is to use the idea of Wheeler (1974). For 2D interface problems, the point is to introduce a small tube near the interface and propose the gradient as part of unknowns, which is similar to a mixed finite element method, but only at the interface. Thus the computational cost is just slightly higher than in the standard finite element method. We present a rigorous one dimensional analysis, which shows a second order convergence order for both the solution and the gradient in 1D. For two dimensional problems, we present numerical results and observe second order convergence for the solution, and super-convergence for the gradient at the interface.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 3; 527-537
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 55

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