Alex Chunghen Chow

Parallel DEVS: a parallel, hierarchical, modular, modeling formalism

We present a revision of the hierarchical, modular Discrete Event System Specification (DEVS) modeling formalism. The revision distinguishes between transition collisions and ordinary external events in the external transition function of DEVS models. Such separation enables us to extend the modeling capability of the collisions. The revision also does away with the necessity for tie-breaking of simultaneously scheduled events, as embodied in the select function. The latter is replaced by a well-defined and consistent formal construct that allows all transitions to be simultaneously activated. The revision provides a modeler with both conceptual and parallel execution benefits.

A performance model for Fast Fourier Transform

The Fast Fourier Transform (FFT) has been considered one of the most important computing algorithms for decades. Its vast application domain makes it an important performance benchmark for new computer architectures. The most common Cooley-Tukey FFT algorithm factorizes a large FFT into a combination of smaller ones. The choice of factors and the order in which they are applied are critical to the ultimate performance of the large FFT.