Simulation Model and Analysis of a Data Warehouse

Data warehouses are large complex systems with many interacting nonlinear components. It is an amalgamation of many different systems and integration of such diverse elements is its primary concern. It is often difficult for a data warehouse manager to predict the performance of the system especially when demand pattern for the required data keeps changing. We have developed a simulation model using ARENA simulation package that will simulate the behavior and performance of a data warehouse system environment based on its overall design. Given such a model, a data warehouse manager can walk through various what-if scenarios and can pinpoint the areas of weaknesses in the system. This visibility could result in improved operational performance in a data warehouse

Preemption in single machine earliness-tardiness scheduling

We consider a single machine earliness/tardiness scheduling problem with general weights, ready times and due dates. Our solution approach is based on a time-indexed preemptive relaxation of the problem. For the objective function of this relaxation, we characterize cost coe±cients that are the best among those with a piecewise linear structure with two segments. From the solution to the relaxation with these best objective function coe±cients, we generate feasible solutions for the original non-preemptive problem. We report extensive computational results demonstrating the speed and effectiveness of this approach

Problema de programação da produção um esquema de classificação

Muitas vezes, não é simples encontrar uma classificação exata para os problemas de programação, não somente porque existem diferentes versões para um dado problema, mas, porque vários procedimentos para uma questão particular, são caracterizados por premissas diferentes e limitações de aplicação dos modelos desenvolvidos. O objetivo deste artigo é delinear uma classificação ampla que permita estabelecer o sentido, direção e perspectiva de pesquisas conduzidas na área. O trabalho não tem a intenção de dar um levantamento exaustivo da literatura de programação da produção, que pode ser encontrado em vários outros trabalhos de revisão.<br>It is the purpose of this article to review the various solutions that have been proposed for the production scheduling problem. An attempt is made to give a classification scheme to categorize the existing procedures that allow to point out potential future courses of development. Emphasis is placed on the basic assumptions involved in each production sequencing problem rather than to approaches used to obtain a solution