Showing papers in "Applications of Mathematics in 2001"
TL;DR: In this paper, Nguetseng's method of two-scale convergence is applied to homogenize and prove corrector results for the Maxwell equations with inhomogeneous initial conditions.
Abstract: The Maxwell equations in a heterogeneous medium are studied. Nguetseng's method of two-scale convergence is applied to homogenize and prove corrector results for the Maxwell equations with inhomogeneous initial conditions. Compactness results, of two-scale type, needed for the homogenization of the Maxwell equations are proved.
78 citations
TL;DR: In this paper, it was shown that for the discrete Poisson equation and under some weak additional assumptions, only the use of Delaunay triangulations preserves the maximum principle.
Abstract: The starting point of the analysis in this paper is the following situation: "In a bounded domain in ℝ2, let a finite set of points be given. A triangulation of that domain has to be found, whose vertices are the given points and which is `suitable' for the linear conforming Finite Element Method (FEM)." The result of this paper is that for the discrete Poisson equation and under some weak additional assumptions, only the use of Delaunay triangulations preserves the maximum principle.
20 citations
TL;DR: In this paper, the authors present some approximate and exact tests for testing variance components in general unbalanced mixed linear models, and extend the results presented by Seifert with emphasis on the computational aspects of the problem.
Abstract: The paper presents some approximate and exact tests for testing variance components in general unbalanced mixed linear model. It extends the results presented by Seifert (1992) with emphasis on the computational aspects of the problem.
15 citations
TL;DR: In this article, the minimum disparity point estimators are studied in regular discrete models with i.i.d. observations and their asymptotic efficiency of the first order, in the sense of Rao, is proved.
Abstract: Disparities of discrete distributions are introduced as a natural and useful extension of the information-theoretic divergences. The minimum disparity point estimators are studied in regular discrete models with i.i.d. observations and their asymptotic efficiency of the first order, in the sense of Rao, is proved. These estimators are applied to continuous models with i.i.d. observations when the observation space is quantized by fixed points, or at random, by the sample quantiles of fixed orders. It is shown that the random quantization leads to estimators which are robust in the sense of Lindsay [9], and which can achieve the efficiency in the underlying continuous models provided these are regular enough.
13 citations
TL;DR: In this paper, a test statistic for testing goodness-of-fit of the Cauchy distribution is presented, which is a quadratic form of the first and of the last order statistic and its matrix is the inverse of the asymptotic covariance matrix of the quantile difference statistic.
Abstract: A test statistic for testing goodness-of-fit of the Cauchy distribution is presented. It is a quadratic form of the first and of the last order statistic and its matrix is the inverse of the asymptotic covariance matrix of the quantile difference statistic. The distribution of the presented test statistic does not depend on the parameter of the sampled Cauchy distribution. The paper contains critical constants for this test statistic, obtained from 50,000 simulations for each sample size considered. Simulations show that the presented test statistic is for testing goodness-of-fit of the Cauchy distributions more powerful than the Anderson-Darling, Kolmogorov-Smirnov or the von Mises test statistic.
13 citations
TL;DR: In this article, the convergence of Newton and approximate Newton methods for nonsmooth equations is established. But the present methods can be more easily implemented than the previous ones, since they do not require an element of Clarke generalized Jacobian, of B-differential, or of b-differentially, at each iteration point.
Abstract: The paper is devoted to two systems of nonsmooth equations. One is the system of equations of max-type functions and the other is the system of equations of smooth compositions of max-type functions. The Newton and approximate Newton methods for these two systems are proposed. The Q-superlinear convergence of the Newton methods and the Q-linear convergence of the approximate Newton methods are established. The present methods can be more easily implemented than the previous ones, since they do not require an element of Clarke generalized Jacobian, of B-differential, or of b-differential, at each iteration point.
11 citations
TL;DR: In this paper, an algorithm for quadratic minimization with simple bounds is introduced, combining, as many well-known methods do, active set strategies and projection steps, where the criterion for acceptance of a projected trial point is weaker than the usual ones, which are based on monotone decrease of the objective function.
Abstract: An algorithm for quadratic minimization with simple bounds is introduced, combining, as many well-known methods do, active set strategies and projection steps. The novelty is that here the criterion for acceptance of a projected trial point is weaker than the usual ones, which are based on monotone decrease of the objective function. It is proved that convergence follows as in the monotone case. Numerical experiments with bound-constrained quadratic problems from CUTE collection show that the modified method is in practice slightly more efficient than its monotone counterpart and has a performance superior to the well-known code LANCELOT for this class of problems.
9 citations
TL;DR: In this article, a discretized boundary value problem for the Laplace equation with the Dirichlet and Neumann boundary conditions on an equilateral triangle with a triangular mesh is transformed into a problem of the same type on a rectangle.
Abstract: A discretized boundary value problem for the Laplace equation with the Dirichlet and Neumann boundary conditions on an equilateral triangle with a triangular mesh is transformed into a problem of the same type on a rectangle. Explicit formulae for all eigenvalues and all eigenfunctions are given.
8 citations
TL;DR: In this paper, it was shown that the vector stop operator with a convex closed characteristic Z of class C1 is locally Lipschitz continuous in the space of absolutely continuous functions.
Abstract: It is known that the vector stop operator with a convex closed characteristic Z of class C1 is locally Lipschitz continuous in the space of absolutely continuous functions if the unit outward normal mapping n is Lipschitz continuous on the boundary ∂Z of Z. We prove that in the regular case, this condition is also necessary.
8 citations
TL;DR: In this paper, the existence of an optimal shape of a deformable body made from a physically nonlinear material obeying a specific nonlinear generalized Hooke's law is proved.
Abstract: Existence of an optimal shape of a deformable body made from a physically nonlinear material obeying a specific nonlinear generalized Hooke's law (in fact, the so called deformation theory of plasticity is invoked in this case) is proved. Approximation of the problem by finite elements is also discussed.
7 citations
TL;DR: In this article, it was shown that the finite element method for one-dimensional problems yields no discretization error at nodal points provided the shape functions are appropriately chosen, and that the Galerkin approximation of u based on the so-called biharmonic finite elements is independent of the values of u in the interior of any subelement.
Abstract: We prove that the finite element method for one-dimensional problems yields no discretization error at nodal points provided the shape functions are appropriately chosen. Then we consider a biharmonic problem with mixed boundary conditions and the weak solution u. We show that the Galerkin approximation of u based on the so-called biharmonic finite elements is independent of the values of u in the interior of any subelement.
TL;DR: Tetrahedral finite C0-elements of the Hermite type satisfying the maximum angle condition are presented and corresponding finite element interpolation theorems in the maximum norm are proved in this article.
Abstract: Tetrahedral finite C0-elements of the Hermite type satisfying the maximum angle condition are presented and the corresponding finite element interpolation theorems in the maximum norm are proved.
TL;DR: In this paper, an elliptic boundary value problem with a nonlinear Newton boundary condition considered in a two-dimensional nonpolygonal domain with a curved boundary was studied, and the effect of the basic finite element variational crimes: approximation of the curved boundary by a polygonal one and the evaluation of integrals by numerical quadratures was analyzed.
Abstract: The paper is concerned with the study of an elliptic boundary value problem with a nonlinear Newton boundary condition considered in a two-dimensional nonpolygonal domain with a curved boundary. The existence and uniqueness of the solution of the continuous problem is a consequence of the monotone operator theory. The main attention is paid to the effect of the basic finite element variational crimes: approximation of the curved boundary by a polygonal one and the evaluation of integrals by numerical quadratures. With the aid of some important properties of Zlamal's ideal triangulation and interpolation, the convergence of the method is analyzed.
TL;DR: In this article, two fully discrete finite element solutions of the nonstationary semiconductor equations were constructed, one was nonlinear, the other was partly linear, and both were shown to converge in a strong norm to the weak solution.
Abstract: In part I of the paper (see Zlamal [13]) finite element solutions of the nonstationary semiconductor equations were constructed. Two fully discrete schemes were proposed. One was nonlinear, the other partly linear. In this part of the paper we justify the nonlinear scheme. We consider the case of basic boundary conditions and of constant mobilities and prove that the scheme is unconditionally stable. Further, we show that the approximate solution, extended to the whole time interval as a piecewise linear function, converges in a strong norm to the weak solution of the semiconductor equations. These results represent an extended and corrected version of results announced without proof in Zlamal [14].
TL;DR: For a second order elliptic equation with a nonlinear radiation-type boundary condition on the surface of a three-dimensional domain, the authors proved existence of generalized solutions without explicit conditions on the trace of solutions.
Abstract: For a second order elliptic equation with a nonlinear radiation-type boundary condition on the surface of a three-dimensional domain, we prove existence of generalized solutions without explicit conditions (like
$$\left. u \right|_\Gamma \in L_5 \left( \Gamma \right)$$
) on the trace of solutions. In the boundary condition, we admit polynomial growth of any fixed degree in the unknown solution, and the heat exchange and emissivity coefficients may vary along the radiating surface. Our generalized solution is contained in a Sobolev space with an exponent q which is greater than
$$9/4$$
for the fourth power law.
TL;DR: In this paper, a numerical scheme based on the relaxation scheme using non-standard time discretization is proposed to solve the problem of degenerate variational inequalities, and the convergence of the method is proved.
Abstract: In this paper we are concerned with the solution of degenerate variational inequalities. To solve this problem numerically, we propose a numerical scheme which is based on the relaxation scheme using non-standard time discretization. The approximate solution on each time level is obtained in the iterative way by solving the corresponding elliptic variational inequalities. The convergence of the method is proved.
TL;DR: In this article, the authors present the solution of some inverse problems for one-dimensional free boundary problems of oxygen consumption type, with a semilinear convection-diffusion-reaction parabolic equation.
Abstract: We present the solution of some inverse problems for one-dimensional free boundary problems of oxygen consumption type, with a semilinear convection-diffusion-reaction parabolic equation. Using a fixed domain transformation (Landau's transformation) the direct problem is reduced to a system of ODEs. To minimize the objective functionals in the inverse problems, we approximate the data by a finite number of parameters with respect to which automatic differentiation is applied.
TL;DR: In this paper, under the maximum angle condition, the finite element method is analyzed for nonlinear elliptic variational problem formulated in [4], and the analysis was done under the minimum angle condition.
Abstract: In this paper, under the maximum angle condition, the finite element method is analyzed for nonlinear elliptic variational problem formulated in [4]. In [4] the analysis was done under the minimum angle condition.
TL;DR: In this article, the error of the general interpolation rule for functions which are real valued on the interval [a, a],a ∈ (0,1), have a holomorphic extension on the unit circle and are quadratic integrable on the boundary of it is estimated.
Abstract: The aim of the paper is to get an estimation of the error of the general interpolation rule for functions which are real valued on the interval [—a, a],a ∈ (0,1), have a holomorphic extension on the unit circle and are quadratic integrable on the boundary of it. The obtained estimate does not depend on the derivatives of the function to be interpolated. The optimal interpolation formula with mutually different nodes is constructed and an error estimate as well as the rate of convergence are obtained. The general extremal problem with free weights and knots is solved.
TL;DR: In this article, the authors describe mobile carrier transport in semiconductor devices with constant densities of ionized impurities using one-dimensional partial differential equations and give the proofs of global existence of solutions of systems of such kind, their bifurcations and their stability under the corresponding assumptions.
Abstract: The present paper describes mobile carrier transport in semiconductor devices with constant densities of ionized impurities. For this purpose we use one-dimensional partial differential equations. The work gives the proofs of global existence of solutions of systems of such kind, their bifurcations and their stability under the corresponding assumptions.
TL;DR: In this paper, a derivative-free estimate of the remainder of an arbitrary interpolation rule on the class of entire functions which, moreover, belong to the space L 2 (−∞,+∞).
Abstract: In the paper we present a derivative-free estimate of the remainder of an arbitrary interpolation rule on the class of entire functions which, moreover, belong to the space L2
(-∞,+∞). The theory is based on the use of the Paley-Wiener theorem. The essential advantage of this method is the fact that the estimate of the remainder is formed by a product of two terms. The first term depends on the rule only while the second depends on the interpolated function only. The obtained estimate of the remainder of Lagrange's rule shows the efficiency of the method of estimate. The first term of the estimate is a starting point for the construction of the optimal rule; only the optimal rule with prescribed nodes of the interpolatory rule is investigated. An example illustrates the developed theory.
TL;DR: In this article, a nonhomogeneous Dirichlet boundary condition on a part Γ 1 of the boundary is studied and the problem is discretized in space by the finite element method with linear functions on triangular elements and in time by the implicit-explicit method.
Abstract: The computation of nonlinear quasistationary two-dimensional magnetic fields leads to a nonlinear second order parabolic-elliptic initial-boundary value problem. Such a problem with a nonhomogeneous Dirichlet boundary condition on a part Γ1 of the boundary is studied in this paper. The problem is discretized in space by the finite element method with linear functions on triangular elements and in time by the implicit-explicit method (the left-hand side by the implicit Euler method and the right-hand side by the explicit Euler method). The scheme we get is linear. The strong convergence of the method is proved under the assumptions that the boundary ∂Ω is piecewise of class C3 and the initial condition belongs to L2 only. Strong monotonicity and Lipschitz continuity of the form a(v,w) is not an assumption, but a property of this form following from its physical background.