On the generalised jump of a function by its Fourier coefficients

Summary Author studies the summability (C,1+α+ρ) of the sequence nB_n(x) under weaker conditions than those ofMinakishisundaram [3] and thus generalises his theorems. on the ? Jump of a function ? and by applying a tauberian theorem obtaing a criteria for the (C, α+ρ) summability of the conjugate series.     

APPROXIMATING ANALYSIS OF A KIND OF REPAIRABLE STANDBY SYSTEMS

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The Hilbert boundary-value problem with a finite index and a countable set of jump discontinuities in coefficients

We consider the Hilbert boundary-value problem with a finite index for the case, when the coefficients in the boundary condition have two infinite sequences of discontinuity points of the first kind. We obtain a formula for the general solution and study the solvability issues.     

Anticipated BSDEs driven by a single jump process

In this paper, we discuss a class of anticipated backward stochastic differential equations related to a finite continuous time single jump process. We prove the existence and uniqueness of the adapted solution. Moreover, a comparison theorem for the solutions is also established.     

Variational formulation of the material failure process in solids by embedded discontinuities model

This work presents a variational formulation of the material failure process, idealized as strain or displacement discontinuities, by weak, strong, or discrete embedded discontinuities into a continuum. It is shown that the solution of the proposed variational formulation may be approximated by different types of finite elements with embedded discontinuities. The developed displacement approximation of a finite element split by the discontinuity leads to a symmetric stiffness matrix, which considers not only the continuity of tractions but also the rigid body relative motions of the portions in which the element is split. The variational formulation of a continuum with more than one discontinuity in its interior is developed. It is shown that this formulation may lead to finite elements with embedded discontinuities that can be classified as displacement, force, mixed, and hybrid models. To show the effectiveness of the proposed formulation, the classical example of a bar under tension is solved using one and 2D finite element approximations. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

Determination of the jump of a function of bounded p-variation by its Fourier series

A formula is obtained for the jump of a function of bounded p-variation at a given point in terms of derivatives of partial sums of its Fourier series.Translated from Matematicheskie Zametki, Vol. 12, No. 1, pp. 19–28, July, 1972.     

A unifying formulation of the discrete and continuum approximations for embedded discontinuities

A methodology for the numerical implementation of embedded discontinuities into the finite element method is developed. This is applicable for the discrete and continuum approximations of discontinuities. The variational formulation of the problem of a solid with discontinuities is established for both approximations, yielding the equations used in this methodology. Three sets of equations are obtained by applying this methodology; all are suitable to be numerically implemented. To show the application potential of this method, the numerical simulation of the formation and propagation of a discontinuity in a concrete specimen is carried out and the results are compared with those from the physical experiment, demonstrating the adequacy of the methodology and its corresponding implementations to model discontinuities. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006     

Stabilization of semi-Markovian jump systems via a quantity limited controller

This paper addresses the stabilization problem of continuous-time semi-Markovian jump systems (s-MJSs), where the quantity of a controller to be designed has a limitation. A principle designing such a controller is proposed based on its stationary probability sequence. Sufficient conditions for the existence of the designed controller are obtained by applying a Lyapunov function approach and presented with LMIs. The controller mentioned above is proved to be a minimal variance approximation of mode-dependent controllers having total modes. More special cases about Markovian switching and without minimal variance approximation are further studied. A practical example is used to demonstrate the effectiveness and superiority of the proposed methods.     

Approximating fixed points of holomorphic mappings in the Hilbert ball

We approximate fixed points of holomorphic and ρ-nonexpansive self-mappings of the Hilbert ball using both continuous and discrete schemes.     

Fast evaluation of the Gaunt coefficients

Addition theorems for vector spherical harmonics require the determination of the Gaunt coefficients that appear in a linearization expansion of the product of two associated Legendre functions. This paper presents an algorithm for the efficient calculation of these coefficients through solving the most appropriate (lower triangular) linear system and derives all relevant recurrence relations needed in the calculation. This algorithm is also applicable to the calculation of the Clebsch-Gordan coefficients that are closely related to the Gaunt coefficients and are frequently encountered in the quantum theory of angular momentum. The new method described in this paper reduces the computing time to , compared to the existing formulation that is widely used. This new method can be applied to the calculation of both low- and high-degree coefficients, while the existing formulation works well only for low degrees.

     

Recovery of a function from the coefficients of its Dirichlet series

Let L(λ) be an entire function of exponential type, letγ(t) be the function associated with L(λ) in the sense of Borel, let \(\bar D\) be the smallest closed convex set containing all the singular points ofγ(t), let λ₀, λ₁, ..., λ_n, ... be the simple zeros of L(λ), and let A \(\bar D\) be the space of functions analytic on \(\bar D\) with the topology of the inductive limit. With an arbitraryf (z) ∈ A( \(\bar D\) ) we can associate the series whereC is a closed contour containing \(\bar D\) , on and inside of whichf (z) is analytic. We give a method of recoveringf (z) from the Dirichlet coefficientsa _n.     

Detection of the singularities of a complex function by numerical approximations of its Laurent coefficients

For several applications, it is important to know the location of the singularities of a complex function: just for example, the rightmost singularity of a Laplace Transform is related to the exponential order of its inverse function. We discuss a numerical method to approximate, within an input accuracy tolerance, a finite sequence of Laurent coefficients of a function by means of the Discrete Fourier Transform (DFT) of its samples along an input circle. The circle may also enclose some singularities, since the method works with the Laurent expansion. The DFT is computed by the FFT algorithm so that, from a computational point of view, the efficiency is guaranteed. The function samples may be obtained by solving a numerical problem such as, for example, a differential problem. We derive, as consequences of the method, some new outcomes able to detect those singularities which are close to the circle and to discover if the singularities are all external or internal to the circle so that the Laurent expansion reduces to its regular or singular part, respectively. Other singularities may be located by means of a repeated application of the method, as well as an analytic continuation. Some examples and results, obtained by a first implementation, are reported.     

Domains of regularity of a harmonic function determined by the coefficients of its power series

Summary Theorems are proved which give a sufficient condition on the coefficients of a harmonic function in order that the function be regular in the domain {(x, y, z) | x < A } and is singular at the point (A, 0, 0). This research was supported in part by the Air Force Office of Scientific Research.     

On the ordering of trees by the Laplacian coefficients

We generalize the results from [X.-D. Zhang, X.-P. Lv, Y.-H. Chen, Ordering trees by the Laplacian coefficients, Linear Algebra Appl. (2009), doi:10.1016/j.laa.2009.04.018] on the partial ordering of trees with given diameter. For two n-vertex trees T₁ and T₂, if c_k(T₁)c_k(T₂) holds for all Laplacian coefficients c_k,k=0,1,…,n, we say that T₁ is dominated by T₂ and write T_1cT₂. We proved that among n vertex trees with fixed diameter d, the caterpillar C_n,d has minimal Laplacian coefficients c_k,k=0,1,…,n. The number of incomparable pairs of trees on 18 vertices is presented, as well as infinite families of examples for two other partial orderings of trees, recently proposed by Mohar. For every integer n, we construct a chain of n-vertex trees of length , such that T₀S_n,T_mP_n and T_icT_i+1 for all i=0,1,…,m-1. In addition, the characterization of the partial ordering of starlike trees is established by the majorization inequalities of the pendent path lengths. We determine the relations among the extremal trees with fixed maximum degree, and with perfect matching and further support the Laplacian coefficients as a measure of branching.     

受控马尔可夫跳线性系统的随机鲁棒稳定性

本文讨论了受控连续和离散时间马尔可夫跳线性系统的随机鲁棒稳定性,并且给出了此时该系统发生马尔可夫跳的转移速率的一个界.     

On a new centered strategy to control the accuracy of weighted essentially non oscillatory algorithm for conservation laws close to discontinuities

In this paper we try to redesign an algorithm analyzed in previous works by Amat et al. in order to obtain a centered strategy aimed to approximate the solution of linear and nonlinear systems of conservation laws. We perform the analysis of the new algorithm in order to explain why the new strategy works close to shocks in the solution of conservation laws. The objective is to force the use of the most centered stencil of those used whenever the data are affected by the presence of a high gradient.     

An estimate of a Dirichlet series with real coefficients on a ray

Best possible conditions are found under which the logarithm of the absolute value of an entire Dirichlet series with real coefficients rarely changing sign increases on the positive ray in the same way as in the whole plane. This result essentially strengthens a similar result due to Pavlov concerning the growth of Taylor series on the positive ray. Translated fromMatematicheskie Zametki, Vol. 60, No. 6, pp. 810–823, December, 1996. This research was supported by the Russian Foundation for Basic Research under grant No. 93-01-00259.