A multicomputer or workstation cluster with multiprocessor nodes introduces signiicant need and opportunity for overlapping communication with computation. We evaluate partitioning strategies for an important application class, nite diierence methods, running on clusters of symmetric multiprocessors. Our results show that even for a regular, uniform nite diierence method, a non-uniform partitio...

The problem of estimating the di erence in arrival times of a noisy sinusoid received at two spatially separated sensors is considered. Given the sinusoidal frequency, a simple delay estimator using the phase di erence of the discrete time Fourier transforms (DTFTs) of the received signals is devised. With the use of periodogram, the algorithm is extended to estimate the delay when the frequenc...

ABSTRACT High order nite di erence WENO methods have the advantage of simpler coding and smaller computational cost for multi-dimensional problems, compared with nite volume WENO methods of the same order of accuracy. However a main restriction is that conservative nite di erence methods of third and higher order of accuracy can only be used on uniform rectangular or smooth curvilinear meshes. ...

A two dimensional nite di erence model for elastic waves in the ground has been developed The model uses the equation of motion and the stress strain relation from which a rst order stress velocity formulation is obtained The resulting system of equations is discretized using centered nite di erences A perfectly matched layer surrounds the discretized solution space and absorbs the outward trav...

Numerical di erentiation formulas based on interpolating polynomials, operators and lozenge diagrams can be simpli ed to one of the nite di erence approximations based on Taylor series. In this paper, we have presented closed-form expressions of these approximations of arbitrary order for rst and higher derivatives. A comparison of the three types of approximations is given with an ideal digita...

Two approaches of multistage gradient robusti cation for image contour detection are presented in this paper: two stages of Di erence of Estimates and Di erence of Estimate followed by an optimal ltering. Watershed transformation is then applied to these robusti ed gradient images to e ectively detect image contours which are guaranteed to be in closed form. Multistage gradient robusti cation p...

We discuss the temporal di erence learning algorithm as applied to approximating the cost to go function of an in nite horizon discounted Markov chain The algorithm we analyze updates parameters of a linear function approximator on line during a single endless traject ory of an irreducible aperiodic Markov chain with a nite or in nite state space We present a proof of convergence with probabili...

Direct numerical simulation of transitional and turbulent hypersonic boundary layers using the Navier-Stokes equations requires high-order accurate numerical methods to resolve a wide range of time and length scales. Compact or explicit nite di erence methods used for such simulation have mainly been central di erence schemes containing only phase errors without any numerical dissipation. Centr...

The analysis of di erences and commonalities between process models or between instances which progressed through the model (henceforth referred to as instance tra c) plays an important role in companies. For example, companies are often confronted with di erent versions or variants of a process model and hence need methods to identify redundancies or inconsistencies between them. Di erencegrap...

With growing concerns about childhood obesity and the associated health risks, several countries are considering banning advertising directed at the children. In this paper we study the e¤ect of a ban on advertizing to children imposed in the Canadian province of Quebec in 1980 on fastfood purchase propensity and expenditures. Fastfood is not only one of the most highly advertised product categ...