Economic efficiency analysis of wafer fabrication

[[abstract]]© 2007 Institute of Electrical and Electronics Engineers - Economic efficiency analysis of semiconductor fabrication facilities (fabs) involves tradeoffs among cost, yield, and cycle time. Due to the disparate units involved, direct evaluation and comparison is difficult. This article employs data envelopment analysis (DEA) to determine relative efficiencies among fabs over time on the basis of empirical data, whereby cycle time performance is transformed into monetary value according to an estimated price decline rate. Two alternative DEA models are formulated to evaluate the influence of cycle time and other performance attributes. The results show that cycle time and yield follow increasing returns to scale, just as do cost and resource utilization. Statistical analyses are performed to investigate the DEA results, leading to specific improvement directions and opportunities for relatively inefficient fabs. Note to Practitioners-Speed of manufacturing is an important metric of factory performance, yet it has long been a challenge to integrate its value into overall performance evaluation. However, for many semiconductor products, a predictable rate of decline in selling prices makes it possible to transform time value into monetary value. This study employs a novel method to incorporate a speed metric into economic efficiency evaluation and thereby provide a guideline for improving fab efficiency in manufacturing practice. Furthermore, this study integrates factory productivity and cycle time into a relative efficiency analysis model that jointly evaluates the impact of these two factors in manufacturing performance. In particular, we validate this approach with data from ten leading wafer fabs obtained by the Competitive Semiconductor Manufacturing Program and we discuss managerial implications.[[department]]工業工程與工程管理學

Application of Evolutionary Algorithms in Project Management

Part 7: Genetic AlgorithmsInternational audienceThe paper deals with “resource leveling optimization problems”, a class of problems that are often met in modern project management. The problems of this kind refer to the optimal handling of available resources in a candidate project and have emerged, as the result of the even increasing needs of project managers in facing project complexity, controlling related budgeting and finances and managing the construction production line. For the effective resource leveling optimization in problem analysis, evolutionary intelligent methodologies are proposed. Traditional approaches, such as exhaustive or greedy search methodologies, often fail to provide near-optimum solutions in a short amount of time, whereas the proposed intelligent approaches manage to quickly reach high quality near-optimal solutions. In this paper, a new genetic algorithm is proposed for the investigation of the start time of the non-critical activities of a project, in order to optimally allocate its resources. Experiments with small and medium size benchmark problems taken from publicly available project data resources, produce highly accurate resource profiles. The proposed methodology proves capable of coping with larger size project management problems, where conventional techniques like complete enumeration is impossible, obtaining near-optimal solutions

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