1,721,296 research outputs found
Commentary: Rheumatic mitral valve disease: Repair when you can, replace when you can't!
No full textEnergy Saving in Link Stability Routing Protocol
Full text linkBecause the CPU is a very expensive resource in mobile ad hoc networks (MANETs), it is very important to consider the overhead introduced in a routing protocol. Many theories have been hypothesized with the aim of minimizing it. But how much is the energy consumption from a network node’s battery induced by the routing protocol overhead? In a previous work, we dealt with a routing protocol based on link stability (link duration observed in a time interval). In this work, we attempt to hypothesize a model for conserving the battery energy consumed by nodes in a MANET adopting the link stability routing protocol
Error bounds for a gauss-type quadrature rule to evaluate hypersingular integrals
No full textIn the present paper we consider hypersingular integrals of the following type (Formula presented) where the integral is understood in the Hadamard finite part sense, p is a positive integer, wα(x) = e−xxαis a Laguerre weight of parameter α ≥ 0 and t > 0. In [6] we proposed an efficient numerical algorithm for approximating (1), focusing our attention on the computational aspects and on the efficient implementation of the method. Here, we introduce the method discussing the theoretical aspects, by proving the stability and the convergence of the procedure for density functions f s.t. f(p)satisfies a Dini-type condition. For the sake of completeness, we present some numerical tests which support the theoretical estimates
Numerical method for hypersingular integrals of highly oscillatory functions on the positive semiaxis
Full text linkThis paper deals with a quadrature rule for the numerical evaluation of hypersingular integrals of highly oscillatory functions on the positive semiaxis. The rule is of product type and consists in approximating the density function f by a truncated interpolation process based on the zeros of generalized Laguerre polynomials and an additional point. We prove the stability and the convergence of the rule, giving error estimates for functions belonging to weighted Sobolev spaces equipped with uniform norm. We also show how the proposed rule can be used for the numerical solution of hypersingular integral equations. Numerical tests which confirm the theoretical estimates and comparisons with other existing quadrature rules are presented
Giant left atrial appendage aneurysm: a source of multiple thrombotic events despite medical therapy
No full textNumerical method for boundary value problems on the real line
No full textThis paper deals with the global approximation of the solutions of Boundary Value Problems (BVPs) of second order on the real line. We first reduce the BVP to an equivalent Fredholm integral equation of the second kind and then approximate its solution by a Nyström type method based on a suitable product quadrature rule. Such quadrature formula is based on a truncated interpolation process at the Hermite zeros. The stability and the convergence of the method as well as the well conditioning of the involved linear systems are studied in weighted spaces of continuous functions. Numerical tests confirming the theoretical error estimates are shown
A numerical method for linear Volterra integral equations on infinite intervals and its application to the resolution of metastatic tumor growth models
Full text linkA Nyström method for linear second kind Volterra integral equations on unbounded intervals, with sufficiently smooth kernels, is described. The procedure is based on the use of a truncated Lagrange interpolation process and of a truncated Gaussian quadrature formula. The stability and the convergence of the method in suitable weighted spaces of functions are studied and some numerical examples showing its reliability are presented. In particular, the proposed method has been tested for the numerical resolution of some Volterra integral equations arising from the reformulation of differential models describing metastatic tumor growth whose unknown solutions represent biological observables as the metastatic mass or the number of metastases
Filtered interpolation for solving Prandtl’s integro-differential equations
No full textIn order to solve Prandtl-type equations we propose a collocation-quadrature method based on de la Vallée Poussin (briefly VP) filtered interpolation at Chebyshev nodes. Uniform convergence and stability are proved in a couple of Hölder-Zygmund spaces of locally continuous functions. With respect to classical methods based on Lagrange interpolation at the same collocation nodes, we succeed in reproducing the optimal convergence rates of the L2 case and cut off the typical log factor which seemed inevitable dealing with uniform norms. Such an improvement does not require a greater computational effort. In particular, we propose a fast algorithm based on the solution of a simple 2-bandwidth linear system and prove that, as its dimension tends to infinity, the sequence of the condition numbers (in any natural matrix norm) tends to a finite limit
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