Y.C. Ho

A Class of Center-Free Resource Allocation Algorithms 1

Abstract This paper presents a class of resource allocation algorithms derived as a projected gradient on a subspace parametrized by a communication constraint. The algorithms have the distinguishing characteristic of converging to the optimal allocation while completely eliminating the need for a coordinating center. Furthermore, during the iteration process the objective function monotonically increases toward its maximum while the allocation always remains feasible. Finally, this paper presents a finite step initialization procedure which yields an initial allocation that has properties required by this class of algorithms.

Vulnerability assessment and allocation of protection resources in power systems

In electrical power grids, there exists the potential for disturbances, even small ones, to trigger cascading collapse and blackout of large portions of the grid. In this paper we propose a simple cascading collapse model. The purpose of the model is to identify topological and component differences that can be exploited for the allocation of protection resources and in designing preventive maintenance schedules. Numerical examples are given to illustrate how the model can be used for protection enhancements and in designing preventive maintenance schedules that reduce vulnerabilities due to hidden failures.

An event domain formalism for sample path perturbation analysis of discrete event dynamic systems

We present a state-space representation of a general discrete event dynamic system (DEDS) model on the basis of a natural event domain, which replaces time. Perturbation analysis of a sample path Of a DEDS is then formalized using some fundamental concepts introduced to establish conditions for its validity. A set of simple perturbation equations is then derived under these conditions, so that performance gradients with respect to parameters are estimated from observation of real or simulated data on a single sample path.

Perturbation analysis of sojourn time in queueing networks

The sample path perturbation analysis technique developed earlier for throughput sensitivity analysis (refs. 1,2) is extended to performance measure involving sojourn time of customers. Numerical experiments and analysis validate this method of computation of the sensitivities.

Credibility and rationality of players strategies in multilevel games

The credibility of threats and the rationality underlying their execution is studied in the context of a Stackelberg game with the reversed information structure, repeated an infinite number of times.

Optimization and Analysis of Discrete Event Stochastic Systems with Application to Manufacturing Automation

Abstract This paper outlines a nonprobabilistic (time domain) approach to the study of discrete event dynamical systems typically represented by queueing networks and production systems in manufacturing. It attempts to unify the development of operational analysis in queueing theory with some recently developed techniques in production systems based on control-theoretic considerations.

Decentralized Stabilization Via Game Theoretic Methods

Abstract Game theoretic ideas are employed in establishing the tradeoffs between control effort and “degree” of stabilization for a class of feedback controls. These control laws are particularly suited for decentralized stabilization of interconnected systems.

Experience with developing and dispensing research results and advanced course materials on the World Wide Web

Under a joint NSP grant on Research and Curriculum Development, principal investigators including faculty members from the Manufacturing Engineering Department of Boston University, the Electrical and Computer Engineering Department of the University of Massachusetts at Amherst, and the Discrete Event Dynamic Systems Group of Harvard University are developing Internet-based software laboratories, demonstrations and teaching modules in the area of DEDS. The main form of dissemination that they propose is to make available a number of course modules of one to three weeks of teaching duration involving electronic laboratory, audio-visual lectures, course notes, homework with solutions, review questions, and quizzes. Our view is that prospective instructors can combine various components as needed in order to create their own courses after downloading the material.

A Road Map for DEDS Research

Abstract That Discrete Event Dynamic Systems (DEDS) constitute an important topic of control system study is no longer in question and while examples of DEDS ranging from airports to communication networks to logistics and service systems abound in our daily lives, the fact remains that a relatively small percentage of control system researchers and an even smaller percentage of practitioners have a comprehensive knowledge of this field that has sprung up during the past decade. The often heard question is how do I get started on the subject?. We should mention at the outset that it is infeasible nor desirable to attempt an encyclopedic listing of all relevant references. This tutorial merely tries to provide a simplified conceptual road map for beginners to get started and to see where we may be going. No value judgements should be attached to works referenced or not referenced. The author is. of course, responsible for his own opinions and perspectives. The last section lists some resources for further study.

Hybrid optimization-an experimental study

The authors compare the performance of a hybrid optimization method to that of pure gradient based methods. The hybrid optimization method comprises an initial adaptive ordinal search phase followed by a gradient ascent (descent) phase. The adaptive ordinal search phase consists of fixing the size of the design population and ranking the members of the population using an estimated value of the performance. Members of the design population for the next stage are picked using the top designs of the previous population. This process is achieved via a variation on the standard genetic algorithm (see D. E. Goldberg, 1989). Ho et al. (1992) showed that ranks of populations are relatively insensitive to simulation noise, and as the experimental data show, this fact is useful in using short simulation runs to improve the search efficiency before the onset of the final gradient ascent (descent) phase.<<ETX>>