Fixed Communication Topology Research Articles

Stability analysis of M-dimensional asynchronous swarms with a fixed communication topology

Coordinated dynamical swarm behavior occurs when certain types of animals forage for food or try to avoid predators. Analogous behaviors can occur in engineering systems (e.g., in groups of autonomous mobile robots or air vehicles). In this paper, we study a model of an M-dimensional (M/spl ges/2) asynchronous swarm with a fixed communication topology, where each member only communicate with fixed neighbors, to provide conditions under which collision-free convergence can be achieved with finite-size swarm members that have proximity sensors, and neighbor position sensors that only provide delayed position information. Moreover, we give conditions under which an M-dimensional asynchronous mobile swarm with a fixed communication topology following an edge-leader can maintain cohesion during movements even in the presence of sensing delays and asynchronism. In addition, the swarm movement flexibility is analyzed. Such stability analysis is of fundamental importance if one wants to understand the coordination mechanisms for groups of autonomous vehicles or robots, where intermember communication channels are less than perfect and collisions must be avoided.

Mobile-Process-Based Parallel Simulation

Our focus is on the novel use of a process-oriented methodology in software systems for parallel simulation on distributed memory. To the best of our knowledge, the few existing systems which adopt a process view strictly use message passing to effect process interaction in distributed-memory settings. As a result, these systems avoid scenarios in which processes directly access passive but shared components. This can restrict the manner in which a system is modeled and hinder the phase of distributed model construction. In this paper, we propose an approach which utilizes mobile processes in distributed-memory simulation systems. The approach entails the migration of a requesting process with its timestamp to the remote site hosting the requested passive object. Major advantages of this approach include one-time transmission, fixed communication topology, and increased locality of reference. Empirical results based on lightweight processes show that the mobile process paradigm can be as efficient as the message-passing paradigm.

Rasterization theory, architectures, and implementations for a class of two-dimensional problems

This paper first presents a theory for rasterizing the class of two-dimensional problems which include signal/image processing, computer vision, and linear algebra. The rasterization theory is steered by an isomorphism relationship between the two-dimensional shuffle exchange network (2DSE) and the two-dimensional butterfly network (2DBN). Since in real-time applications, data are often acquired in a raster scan format, it is important to develop architectures to support the raster data structure. Algorithms are developed first by using 2DSE network, then transformed into 2DBN format. Rasterization architectures can be derived for the algorithms described by 2DBN format. In the PEACE project, we have been able to show that a single, fixed communication topology, namely 2DSE, provides solution times on a 2DSE parallel computing system that for many problems approach known theoretical lower bounds. Secondly, this paper presents the generic architectures and VLSI implementation examples for the rasterization structures.