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EN
In this paper, asymptotic formulae for solutions and Green’s function of a boundary value problem are investigated when the equation and the boundary conditions contain a spectral parameter.
EN
The main goal of this study is the investigation of discontinuous boundary-value problems for second-order differential operators with symmetric transmission conditions.We introduce the new notion of weak functions for such type of discontinuous boundary-value problems and develop an operator-theoretic method for the investigation of the spectrum and completeness property of the weak eigenfunction systems. In particular, we define some self-adjoint compact operators in suitable Sobolev spaces such that the considered problem can be reduced to an operator-pencil equation. The main result of this paper is that the spectrum is discrete and the set of eigenfunctions forms a Riesz basis of the suitable Hilbert space.
EN
This research paper is an attempt to solve the unsteady state convection diffusion one dimension equation. It focuses on the fully implicit hybrid differencing numerical finite volume technique as well as the fully implicit central differencing numerical finite volume technique. The simulation of the unsteady state convection diffusion problem with a known actual solution is also used to validate both the techniques, respectively, the fully implicite hybrid differencing numerical finite volume technique as well as the fully implicit central differencing numerical finite volume technique by giving a particular example and solving it using the appropriate, particular technique. It is observed that the numerical scheme is an outstanding deal with the exact solution. Numerical results and graphs are presented for different Peclet numbers.
EN
The paper reviews the static equilibrium of a micropolar porous elastic material. We assume that the body under consideration is an elastic Cosserat media with voids, however, it can also be considered as an elastic microstretch solid, since the basic differential equations and mathematical formulations of boundary value problems in these two cases are actually identical. As regards the three-dimensional case, the existence and uniqueness of a weak solution of some boundary value problems are proved. The two-dimensional system of equations corresponding to a plane deformation case is written in a complex form and its general solution is presented with the use of two analytic functions of a complex variable and two solutions of the Helmholtz equations. On the basis of the constructed general representation, specific boundary value problems are solved for a circle and an infinite plane with a circular hole.
EN
Cases where the derivative of a boundary value problem does not exist or is constantly changing, traditional derivative can easily get stuck in the local optima or does not factually represent a constantly changing solution. Hence the need for evolutionary algorithms becomes evident. However, evolutionary algorithms are compute-intensive since they scan the entire solution space for an optimal solution. Larger populations and smaller step sizes allow for improved quality solution but results in an increase in the complexity of the optimization process. In this research a population-distributed implementation for differential evolution algorithm is presented for solving systems of 2nd-order, 2-point boundary value problems (BVPs). In this technique, the system is formulated as an optimization problem by the direct minimization of the overall individual residual error subject to the given constraint boundary conditions and is then solved using differential evolution in the sense that each of the derivatives is replaced by an appropriate difference quotient approximation. Four benchmark BVPs are solved using the proposed parallel framework for differential evolution to observe the speedup in the execution time. Meanwhile, the statistical analysis is provided to discover the effect of parametric changes such as an increase in population individuals and nodes representing features on the quality and behavior of the solutions found by differential evolution. The numerical results demonstrate that the algorithm is quite accurate and efficient for solving 2nd-order, 2-point BVPs.
EN
The aim of this article is to introduce the reproducing kernel algorithm for obtaining the numerical solutions of fractional order systems of Dirichlet function types. The algorithm provide appropriate representation of the solutions in infinite series formula with accurately computable structures. By interrupting the n-term of exact solutions, numerical solutions of linear and nonlinear time-fractional equations of homogeneous and nonhomogeneous function type are studied from mathematical viewpoint. Convergence analysis, error estimations, and error bounds for the present algorithm are also discussed. The dynamical properties of these numerical solutions are discussed and the profiles of several representative numerical solutions are illustrated. Finally, the utilized results show that the present algorithm and simulated annealing provide a good scheduling methodology to such systems compared with other numerical methods.
EN
Assume the eigenvalues and the weights are given for a difference boundary value problem and that the form of the boundary conditions at the endpoints is known. In particular, it is known whether the endpoints are fixed (i.e. Dirichlet or non-Dirichlet boundary conditions) or whether the endpoints are free to move (i.e. boundary conditions with affine dependence on the eigenparameter). This work illustrates how the potential as well as the exact boundary conditions can be uniquely reconstructed. The procedure is inductive on the number of unit intervals. This paper follows along the lines of S. Currie and A. Love, Inverse problems for difference equations with quadratic eigenparameter dependent boundary conditions, Quaestiones Mathematicae, 40 (2017), no. 7, 861-877. Since the inverse problem considered in this paper contains more unknowns than the inverse problem considered in the above reference, an additional spectrum is required more often than was the case in the unique reconstruction of the potential alone.
EN
We investigate the behaviour of weak solutions to the nonlocal Robin problem for linear elliptic divergence second order equations in a neighbourhood of the boundary corner point. We find the exponent of the solution decreasing rate under the assumption that the leading coefficients of the equations do not satisfy the Dini-continuity condition.
EN
The aim of this paper is the study the Poisson integral for Hermite expansions. We present some boundary value problems related to this integral and its various modifications.
EN
The R package bvpSolve for the numerical solution of Boundary Value Problems (BVPs) is presented. This package is free software which is distributed under the GNU General Public License, as part of the R open source software project. It includes some well known codes to solve boundary value problems of ordinary differential equations (ODEs) and differential algebraic equations (DAEs). In addition to the packages already available for solving initial value problems, the new package now allows non expert users to efficiently solve boundary value problems in the problem solving environment R.
EN
An application of the Entropy Generation Minimization principle allows new formulation of the boundary and initial boundaryvalue problems. Applying Euler-Lagrange variational formalism new mathematical form of heat conduction equation describing steady-state processes have been derived. Mathematical method presented in the paper can also be used for any diffusion heat and mass transfer process. Linear and non-linear problems with internal heat sources have been analyzed.
PL
Celem niniejszej pracy jest zbadanie możliwości zastosowania nowoczesnych rozwiązań równoległego przetwarzania danych w celu przyspieszenia procesu obliczeniowego pojawiającego się w trakcie numerycznego rozwiązywania PURC. Autorzy wzięli pod uwagę możliwość wykorzystania procesorów kart graficznych do obliczeń numerycznych w zastosowaniach ogólnych (general-purpose GPU – GPGPU), a w szczególności technologię CUDA (Compute Unified Device Architecture) firmy NVidia®.
EN
The main purpose of this paper is examination of an application of modern parallel computing solutions to speed up the calculation in the numerical solution of parametric integral equations systems (PIES). The authors considered use of graphics cards programming in general-purpose applications (GPGPU), particularly NVidia® CUDA (Compute Unified Device Architecture).
13
Content available remote The Voronovskaya type theorem for Poisson integrals of functions of two variables
EN
The aim of this paper is the study the Voronovskaya type theorem for Poisson integrals of functions of two variables for Hermite and Laguerre expansions. We also present some boundary value problems related to these integrals.
PL
W pracy zaprezentowano technikę aproksymacji pochodnych rozwiązań zagadnień brzegowych otrzymywanych za pomocą metody PURC. Celem jej opracowania było uniknięcie obliczania tych pochodnych analitycznie (co jest dość skomplikowane, a nawet niemożliwe) lub numerycznie w konkretnych punktach (ze względu na czasochłonność i nieefektywność) Efektywność zaproponowanej techniki polega na obliczaniu pochodnych w sposób ciągły i w dowolnych punktach na brzegu oraz w obszarze za pomocą otrzymanych szeregów aproksymujących. Wiarygodność i dokładność strategii została przetestowana na przykładach z rozwiązaniami analitycznymi.
EN
The paper presents a technique for the approximation of the derivatives of boundary problems solutions obtained by PIES. The main aim was to avoid calculating these derivatives analytically (which is quite complicated, even impossible) or numerically at specific points (because it is time consuming and inefficient). The effectiveness of the proposed technique consists of computing the derivatives in a continuous way and at any points of the boundary and area by developed approximating series. The reliability and accuracy of the strategy has been tested on examples with analytical solutions.
EN
In this paper the possibilities and limits of solving equations of motion with non-material boundary conditions are investigated. Therefore the system of equations for the nonstationary motion of a three-dimensional body is derived. To overcome the time dependency of the boundary conditions an Arbitrary Lagrangean Eulerian (ALE) kinematics is used. In combination with the introduced operator notation a very clear formulation of the system of the equations of motion is derived. The model of a perfect flexible and inextensible string is used as an illustration. In this case analytical solutions are given in a closed form for an example with one non-material boundary condition. This allows studying the characteristics of such boundary conditions.
16
Content available remote Mesh-free methods and time integrations for transient heat conduction
EN
The paper deals with transient heat conduction in functionally gradient materials. The spatial variation of the temperature field is approximated by using alternatively two various mesh free approximations,while the time dependence is treated either by the Laplace transform method and/or by the polynomialinterpolation in the time stepping method. The accuracy and convergence of the numerical results as well as the computational e?ciency of various approaches are compared in numerical test example.
PL
W pracy przedstawiono globalny sposób numerycznego obliczania całek powierzchniowych w dwuwymiarowych zagadnieniach brzegowych. Prezentowana technika opiera się na matematycznym zdefiniowaniu obszarów za pomocą parametrycznych płatów powierzchniowych oraz wykorzystaniu kwadratur całkowania numerycznego wyższych rzędów. Praktyczną realizację proponowanej procedury przedstawiono dla zagadnień brzegowych definiowanych równaniem Poissona.
EN
The paper presents a novel technique for global considerations and numerical integration of domains in 2D boundary problems. It base on computation of these integrals in global way, i.e. without division of the domain into cells. In proposed approach the domain is treated globally as single parametric surface and using numerical quadratures of high orders. Included numerical examples for boundary problems described by Poisson confirm high accuracy of proposed method compared with analytical results
EN
This article is concerned with the existence result of the unilateral problem associated to the equations of the type Au - divφ(u) = ∫ ∈ L1 (Ω), where A is a Leray-Lions operator having a growth not necessarily of polynomial type and Φ ∈ C0 (R,RN).
EN
The use of iterated deferred correction has proved to be a very efficient approach to the numerical solution of general first order systems of nonlinear two-point boundary value problems. In particular the two high order codes TWPBVP.f, based on mono-implicit Runge-Kutta (MIRK) formulae, and TWPBVPL.f based on Lobatto Runge-Kutta formulae as well as the continuation codes ACDC.f and COLMOD.f are now widely used. In this survey we describe some of the problems involved in the derivation of efficient deferred correction schemes. In particular we consider the construction of high order methods which preserve the stability of the underlying formulae, the choice of the mesh choosing algorithm which is based both on local accuracy and conditioning, and the computation of continuous solutions.
20
Content available remote Superlinear elliptic systems with distributed and boundary controls
EN
The paper investigates the nonlinear partial differential equations of the superlinear elliptic type with the Dirichlet boundary data. Some sufficient conditions, under which the solutions of considered equations depend continuously on distributed and boundary controls, are proved. The proofs of the main results are based on variational methods.
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