The Computational Singular Perturbation (CSP) method, developed by Lam and Goussis [Twenty-Second Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1988, pp. 931–941], is a commonly-used method for finding approximations of slow manifolds in systems of ordinary differential equations (ODEs) with multiple time scales. The validity of the CSP method was established fo...

Abstract: Scattering properties of a material are changed when the material is injected with small acoustically soft particles. It is shown that its new scattering behaviour can be understood as a solution of a potential scattering problem with the potential q explicitly related to the density of the small particles. In this paper we examine the inverse problem of designing a material with the ...

We devise a numerical method for passive advection of a surface, such as the interface between two incompressible fluids, across a computational mesh. The method is called isoAdvector, and is developed for general meshes consisting of arbitrary polyhedral cells. The algorithm is based on the volume of fluid (VOF) idea of calculating the volume of one of the fluids transported across the mesh fa...

We discuss here some computational aspects of the Combinatorial Nullstellensatz argument. Our main result shows that the order of magnitude of the symmetry group associated with permutations of the variables in algebraic constraints, determines the performance of algorithms naturally deduced from Alon’s Combinatorial Nullstellensatz arguments. Finally we present a primal-dual polynomial constru...

Several models of language acquisition have emerged in recent years that rely on computational algorithms for simulation and evaluation. Computational models are formal and precise, and can thus provide mathematically well-motivated insights into the process of language acquisition. Such models are amenable to robust computational evaluation, using technology that was developed for Information ...

We investigate inductive methods for proving secrecy properties of network protocols, in a “computational” setting applying a probabilistic polynomial-time adversary. As in cryptographic studies, our secrecy properties assert that no probabilistic polynomial-time distinguisher can win a suitable game presented by a challenger. Our method for establishing secrecy properties uses inductive proofs...

Discrepancy theory investigates how uniform nonrandom structures can be. For example, given n points in the plane, how should we color them red and blue so as to minimize the difference between the number of red points and the number of blue ones within any disk? Or, how should we place n points in the unit square so that the number of points that lie within any given triangle in the square is ...

A reversible grammar is usually understood as a computational or linguistic system that can be used both for analysis ~nd generation of the language it defines. For example, a directive pars_gen (Sent,For~n) would assign, depending upon the binding status Of its arguments, the representation in (Toronto,chased (Fido,John )) to the sentence Fido chased John in To~onto, or it would produce one of...

This paper presents a stochastic meshless method for probabilistic analysis of linear-elastic structures with spatially varying random material properties. Using Karhunen-Loève (K-L) expansion, the homogeneous random field representing material properties was discretized by a set of orthonormal eigenfunctions and uncorrelated random variables. Two numerical methods were developed for solving th...

We propose a computational calibration method for optical tomography. The model of the calibration scheme is based on the rotation symmetry of source and detector positions in the measurement setup. The relative amplitude losses and phase shifts at the optic fibers are modeled by complex-valued coupling coefficients. The coupling coefficients can be estimated when optical tomography data from a...