Let u^ be a Ritz-Galerkin approximation, corresponding to the solution u of an elliptic boundary value problem, which is based on a uniform subdivision in the interior of the domain. In this paper we show that by "averaging" the values of Uu in the neighborhood of a point x we may (for a wide class of problems) construct an approximation to u(x) which is often a better approximation than UyAx) ...

We give a convergence estimate for a Petrov-Galerkin Algebraic Multigrid method. In this method, the prolongations are defined using the concept of smoothed aggregation while the restrictions are simple aggregation operators. The analysis is carried out by showing that these methods can be interpreted as variational Ritz-Galerkin ones using modified transfer and smoothing operators. The estimat...

We analyze the Ritz–Galerkin method for symmetric eigenvalue problems and prove a priori eigenvalue error estimates. For a simple eigenvalue, we prove an error estimate that depends mainly on the approximability of the corresponding eigenfunction and provide explicit values for all constants. For a multiple eigenvalue we prove, in addition, apparently the first truly a priori error estimates th...

Linear multistep methods are considered which have a stability region S and are D-stable on the whole boundary S c S of S. Error estimates are derived which hold uniformly for the class of initial value problems Y’ AY + B(t), t > 0, Y(0) Y with normal matrix A satisfying the spectral condition Sp(AtA) S At O time step, Sp(A) spectrum of A. Because of this property, the result can be applied to ...

[1] A variety of observations have shown strong seasonal variations in a vast array of magnetosphere-ionosphere parameters, including field-aligned currents, cross polar cap potential, and precipitating electron energy flux. In this paper we examine how these variations are modeled in the Lyon-Fedder-Mobarry (LFM) global-scale magnetohydrodynamic simulation of the coupled solar wind-magnetosphe...

the parameters of infiltration equations have a key role to evaluate and design irrigation systems and it is essential to estimate them with high accuracy for increasing irrigation efficiency. in the present study, two approaches consisting multilevel optimization method using advance, recession and runoff data and the iparm model using advance and runoff data were compared for estimating infil...

This paper presents a method for designing the control loop for dc-to-dc converters when uncertainties exist in the ac characteristics of the converter’s load. In the proposed method, a converter is initially considered as a stand-alone module feeding a current sink load and the control loop of the converter is then designed in a way that maximizes the robustness of the converter’s closed-loop ...

This paper proposes a novel method to schedule parallel execution of planning and action of a mobile robot. The method considers the following two types of parallelism. (1) acting while planning: if a partial planning result can be used to determine feasible actions, such actions can be executed while the planning process is still going. (2) planning while acting: if the result of the current a...

This paper proposes a novel method to schedule parallel execution of planning and action of a mobile robot. The method considers the following two types of parallelism. (1) acting while planning: if a partial planning result can be used to determine feasible actions, such actions can be executed while the planning process is still going. (2) planning while acting: if the result of the current a...