Abstract

Abstract

Abstract
We consider the formulation of non-preemptive single machine scheduling problems using time-indexed variables. This approach leads to very large models, but gives better lower bounds than other mixed integer programming formulations. We derive a variety of valid inequalities, and show the role of constraint aggregation and the knapsack problem with generalised upper bound constraints as a way of generating such inequalities. A cutting plane/branch-and-bound algorithm based on these inequalities has been implemented. Computational experience on small problems with 20/30 jobs and various constraints and objective functions is presented.

Abstract
Visual Interactive Simulation (VIS) is a simulation technique which generates a dynamic display of the model and enables the user to interact with the model while the simulation is running. AWARD (Advanced Warehouse Design) is a VIS system that has been developed by an international consortium of academic institutions and distribution professionals to allow the evaluation of conventional and automated warehouse systems. AWARD uses Computer Aided Design (CAD) techniques for drawing the warehouse layout and configuring the simulation model. The user has no need for programming skills and a user-friendly interface makes it easy to use. High resolution colour graphics and a scale drawing of the warehouse makes the dynamic display of the model a good representation of the real system. This paper will present the development of AWARD, and will discuss the role of the current version in the overall framework of a Decision Support System for warehouse design. The advantages of data-driven generic models as a decision making tool will be highlighted and the use of high-resolution graphics, animation and interactive techniques for improving the communication between the user and the model will be discussed. © 1992 Taylor & Francis Group, LLC.

Abstract
The author describes a man-computer interactive mass transit crew scheduling module which was developed as a component of a Decision Support System (DSS) implemented in a personal computer at the Oporto Urban Transport Authority (STCP). The problem of crew scheduling is briefly discussed and set in the context of the broader process of the planning and control of urban transport services. The general philosophy and the structure of the module are analysed. A crew scheduling heuristic based method is presented. Particular attention is paid to the interactive nature of the approach adopted. Results of the actual implementation process at STCP are given.

Abstract
The aim of this paper is to illustrate primarily the suitability and secondly the ability of both PHM and ‘two-sample’ tests in answering problems in the reliability field. The findings stress the fact that ‘two-sample’ tests should be preferred for comparison purposes and PHM for modelling the behaviour of the equipment in the presence of various factors. Copyright © 1991 John Wiley & Sons, Ltd.