Jon G. Kuhl

A taxonomy of scheduling in general-purpose distributed computing systems

One measure of the usefulness of a general-purpose distributed computing system is the systems ability to provide a level of performance commensurate to the degree of multiplicity of resources present in the system. A taxonomy of approaches to the resource management problem is presented in an attempt to provide a common terminology and classification mechanism necessary in addressing this problem. The taxonomy, while presented and discussed in terms of distributed scheduling, is also applicable to most types of resource management. >

Distributed fault-tolerance for large multiprocessor systems

Techniques for dealing with hardware failures in very large networks of distributed processing elements are presented. A concept known as distributed fault-tolerance is introduced. A model of a large multiprocessor system is developed and techniques, based on this model, are given by which each processing element can correctly diagnose failures in all other processing elements in the system. The effect of varying system interconnection structures upon the extent and efficiency of the diagnosis process is discussed, and illustrated with an example of an actual system. Finally, extensions to the model, which render it more realistic, are given and a modified version of the diagnosis procedure is presented which operates under this model.

Introduction to the non-rigid image registration evaluation project (NIREP)

Non-rigid image registration (NIR) is an essential tool for morphologic comparisons in the presence of intra- and inter-individual anatomic variations. Many NIR methods have been developed, but are especially difficult to evaluate since point-wise inter-image correspondence is usually unknown, i.e., there is no “Gold Standard” to evaluate performance. The Non-rigid Image Registration Evaluation Project (NIREP) has been started to develop, establish, maintain, and endorse a standardized set of relevant benchmarks and metrics for performance evaluation of nonrigid image registration algorithms. This paper describes the basic framework of the project.

The Iowa Driving Simulator: an immersive research environment

This simulators rich, fully interactive environment provides varied scenarios for meeting experimental needs-for example, engineering evaluation of automated highway systems. >

THE IOWA DRIVING SIMULATOR : AN IMPLEMENTATION AND APPLICATION OVERVIEW

This paper gives an overview of the Iowa Driving Simulator (IDS) designed to create high fidelity, operator-in-the-loop vehicle simulation and realistic cueing feedback to the driver. The paper refers to a number of human factors issues that are currently being investigated. Focus is on two specific applications of the IDS: a study of Automated Highway Systems (AHS) and vehicle virtual prototyping on a virtual proving ground.

A Recursive Formulation for Constrained Mechanical System Dynamics: Part III. Parallel Processor Implementation

ABSTRACT A high speed dynamic simulation algorithm that exploits emerging parallel processor computer technology is presented. Medium grain parallelism is defined by the graph structure of a mechanism and the recursive algorithm derived in parts I and II of this paper, for both open and closed loop systems. An off-road vehicle with a suspension system that has eight closed loops is used to illustrate the parallel processor algorithm. A shared memory multiprocessor is used to implement the algorithm and to investigate parallel processing speed-up and overhead. Real-time simulation of a ground vehicle is demonstrated.

Effects of response and stability on scheduling in distributed computing systems

An examination is made of the effects of response and stability on scheduling algorithms for general-purpose distributed computing systems. Response characterizes the time required, following a perturbation in the system state, to reach a new equilibrium state. Stability is a measure of the ability of a mechanism to detect when the effects of further actions will not improve the system state as defined by a user-defined objective. These results have implications for distributed computations in general. Analysis is based on formal communicating finite automata models of two distinct approaches to the scheduling problem, each using the objective of global optimal load balancing. The results indicate that absolute stability is not always necessary in dynamic systems for the same reasons that relatively small amounts of instability are tolerated in the design of analog control systems. It is shown that response is a very important first-order metric of dynamic scheduling behavior, and that response and stability are related. >

A fuzzy-based distributed load balancing algorithm for large distributed systems

The paper presents a new approach to load balancing for large distributed systems. The approach characterizes the global state uncertainty inherent in a large distributed system in terms of the fuzzy set theory and presents a fuzzy-based distributed load balancing algorithm that explicitly reflects the effect of the uncertainty in the decision making process. The notion of linguistic variables is used to model state variables that have imprecise and uncertain state values and fuzzy control to estimate the amount of consistency relaxation from the states of uncertainty sources. A fuzzy-based consistency model provides a mechanism that allows each node to make flexible scheduling and state update decisions based on the estimated degree of consistency relaxation. Simulation results show that the proposed algorithm yields a better performance, substantially reduces the number of messages required, and generally transfers fewer tasks, compared to two conventional distributed load balancing algorithms.<<ETX>>

A communicating finite automata approach to modeling distributed computation and its application to distributed decision-making

A modeling technique for distributed computation based on a combination of directed graphs and finite automata is described. The paradigm of distributed decision-making (DDM) is used to illustrate the technique for its two primary purposes: providing a standard specification mechanism for different algorithms for solving the same problem and providing a common mechanism for objective quantitative evaluation and comparison of alternative DDM algorithms. This is accomplished through the definition of the terms performance and efficiency as they relate to the domain of DDM. The two terms, which have precise meanings with respect to the analysis of sequential algorithms, currently lack a common interpretation in the environment of DDM. In particular, they need to be expressed in terms of the information movement necessary to share state information. The method has been used extensively to conduct analyses of several distribution scheduling algorithms. This paper focuses on the model specification properties. >

Distributed Fault-Tolerance of Tree Structures

Tree structures, as the interconnection structure in networks of many processing elements, have interesting features such as regularity ease of expansion, simple routing, simple addressing, suitability for VLSI/WSI implementation, etc. Distributed fault tolerance of these networks is considered. It is assumed that in these structures, there does not exist any central failure-free entity for providing services such as diagnosis of faulty components, system reconfiguration after failure, control, or coordination among the processing elements. Every processing element is able to diagnose the condition of every other node or internode communication paths via a truly distributed scheme.