Thursday, December 9. 2010
Keywords: fundamental solution method, periodic plane elasticity
Abstract: We present a fundamental solution method for elasticity problems of planes with onedimensional periodic structure, to which it is difficult to apply the conventional fundamental solution method. We propose an approximate solution of the fundamental solution method which is modied so that it is suitable to our problems. Numerical example is also included.
Download Full PDF
Thursday, December 9. 2010
Keywords: circular cylinder, wallmounted, LES, DES, imaging measurements
Abstract: Numerical simulations of the turbulent separated flow around a wallmounted finite cylinder were performed in order to assess the predictive accuracy of the methods for the unsteady flow field at high Reynolds number. While the results obtained from LargeEddy Simulation show only minor diferences to experiments, the DetachedEddy Simulation exhibits problems in the attached laminar boundary layer. By neglecting this insufcient modelling of the transition phenomenon, the DetachedEddy Simulation performed can be understood as a LargeEddy Simulation with an alternative subgrid scale model that delivers qualitatively comparable results to the LargeEddy Simulation.
Download Full PDF
Thursday, December 9. 2010
Keywords: predatorprey model, equilibria, stochastic diferential equation, stochastic stability.
Abstract: We develop a mathematical model for understanding the eect of wanderer spiders as biological controllers of the insects infesting vineyards, thus accounting also for the role played by residual wood and green patches as spiders habitat in the otherwise homogeneuous landscape of the Langhe region. We then extend the deterministic model allowing random uctuations around the coexistence equilibrium. The stochastic stability properties of the model are investigated both analytically and numerically.
Download Full PDF
Thursday, December 9. 2010
Keywords: Backward Difference Formula; Circuit simulation; Differentialalgebraic equations; Discretization error; Multirate; Numerical time integration; Partitioning; Transient analysis
Abstract: Transient analysis is an important circuit simulation technique. The circuit model, which is a system of differentialalgebraic equations, is solved for a given initial condition using numerical time integration techniques. Multirate methods are efficient if the dynamical behaviour of the circuit model is not uniform. This paper deals with the analysis and control of the discretization errors for multirate time integration methods.
c 2008 European Society of Computational Methods in Sciences and Engineering
Download Full PDF
Thursday, December 9. 2010
Keywords: Helly's theorem; set of width; set of constant width Mathematics Subject Classifcation: 52A01
Abstract: In this paper, we prove that, for a given positive number d, if every n + 1 of a collection of compact convex sets in IEn contain a set of width d (a set of constant width d, respectively) simultaneously, then all members of this collection contain a set of constant width d1 simultaneously, where d1 = d=pn if n is odd and d1 = dpn + 2= (n + 1) if n is even (d1 = 2d � d p 2n=(n + 1), respectively). This set is called common set (of constant width d1) of the collection. These results deal with an open question raised by Buchman and Valentine in [Croft, Falconer and Guy, Unsolved Problems in Geometry, SpringerVerlag New York, Inc. 1991, pp. 131132]. Moreover, given an oracle which accepts n + 1 sets of a collection of compact convex sets in IEn and either returns a set of width d (a set of constant width d) contained in these sets, or reports its nonexistence, we present an algorithm which determines a common set of the collection.
Wednesday, December 8. 2010
Abstract: Algorithmbased computers are programmed, i.e., there must be a set of rules which, a priori, characterize the calculation that is implemented by the computer. Neural computation, based on neural networks, solve problems by learning, they absorb experience, and modify their internal structure in order to accomplish a given task. In the learning process, the available information is usually divided into two categories, examples of function values or training data and prior information, e.g. smoothness constraint, or other particular properties [3]. From the learning point of view, the approximation of a function is equivalent with the learning problem of a neural network. In this paper we want to show the capabilities of a neural network to approximate arbitrary continuous functions and to build a practical neural network to approximate a continuous function. We have made some experiments in order to confirm the theoretical results.
Download Full PDF
Wednesday, December 8. 2010
Keywords: nodal splines, singular integral equations
Abstract: In this paper we introduce a nodal spline collocation method for the numerical solution of Cauchy singular integral equations. Uniform error bounds of the approximate solution are provided and some numerical examples are presented.
Download Full PDF
Wednesday, December 8. 2010
Keywords: Linear Multistep Methods, Boundary Value Methods, Conditioning, Vandermonde matrix, Bernstein polynomials, BjorkPereyra algorithm
Abstract: The numerical solution of Boundary Value Problems usually requires the use of an adaptive mesh selection strategy. For this reason, when a Linear Multistep Method is considered, a dynamic computation of its coeffcients is necessary. This leads to solve linear systems which can be expressed in dierent forms, depending on the polynomial basis used to impose the order conditions. In this paper, we compare the accuracy of the numerically computed coecients for three dierent formulations. For all the considered cases Vandermonde systems on general abscissae are involved and they are always solved by the BjorkPereyra algorithm [3]. An adaptation of the forward error analysis given in [8, 9] is proposed whose signicance is conrmed by the numerical results.
Download Full PDF
