17448440
Effective implementation of cycle time reduction strategies for semiconductor back-end manufacturing
Using discrete event simulation models, a study was conducted to evaluate the current production practices of a high volume semiconductor back-end operation. The overall goal was to find potential areas for productivity improvement that would collectively yield a 60% reduction in manufacturing cycle time. The paper presents the simulation methodology and findings pertaining to analysis of the Assembly, Burn-In, and Test operations. Many of the recommendations identified can be implemented at no additional cost to the factory. The most significant opportunities for improvement are in the Test area, the system constraint. Additionally, the model is extremely sensitive to changes in operator staffing levels, an accurate reflection of many back-end operations. The model shows that the cumulative impact of these recommendations is a 41% reduction in average cycle time, a significant contribution to the overall goal.
5441653
Integrating targeted cycle-time reduction into the capital planning process
This paper describes the development and application of an integrated static capacity and dynamic simulation analysis methodology for purchasing equipment capacity. The goal of the study is to address targeted cycle time objectives in a start up recording head wafer manufacturing facility at Seagate Technology, Minneapolis, MN. The short product cycle time, coupled with the competitive nature of the disc drive industry, has made cycle time reduction one of the most important objectives of production capacity planning. This paper describes an equipment procurement strategy in which static capacity analysis is used to identify an initial equipment set with a low slack capacity variable on each tool group. Simulation analysis is then used to identify the critical tool groups that contribute to cycle time delays. The Seagate Industrial Engineering team used the simulation analysis tool Factory Explorer(R) from Wright, Williams and Kelly to perform the cycle time reduction analysis. This targeted approach is compared to the traditional static capacity planning approach of globally applying reserve capacity buffers of 20% or more to achieve the same cycle time reduction goal. Overall, the targeted approach has proven to be efficient in terms of minimizing capital equipment expenditures and also effective on the factory floor.
14389185
A Machine-Oriented Logic Based on the Resolution Principle
:tb.~tract. Theorem-proving on the computer, using procedures based on the fund~mental theorem of Herbrand concerning the first-order predicate etdeulus, is examined with ~ view towards improving the efticieney and widening the range of practical applicability of these procedures. A elose analysis of the process of substitution (of terms for variables), and the process of t ruth-funct ional analysis of the results of such substitutions, reveals that both processes can be combined into a single new process (called resolution), i terating which is vastty more ef[ieient than the older cyclic procedures consisting of substitution stages alternating with truth-functional analysis stages. The theory of the resolution process is presented in the form of a system of first<~rder logic with .just one inference principle (the resolution principle). The completeness of the system is proved; the simplest proof-procedure based oil the system is then the direct implementation of the proof of completeness. Howew~r, this procedure is quite inefficient, ~nd the paper concludes with a discussion of several principles (called search principles) which are applicable to the design of efficient proof-procedures employing resolution as the basle logical process.
28156050
An Introduction to Hyperarithmetical Functions
14933774
Using a Network of Workstations to Enhance Database Query Processing Performance
Query processing in database systems may be improved by applying parallel processing techniques. One reason for improving query response time is to support the increased number queries when databases are made accessible from the Internet.
6479052
Data Analysis for Query Processing
Data analysis is needed in connection with query processing, to produce data summary information in the form of rules or assertions that allow semantic query optimisation or direct query answering without consulting the data itself. The goal of an intelligent analyser in this context is to produce robust rules, stable in the presence of data changes, which allow easy rule maintenance as data changes, and provide rapid query reformulation, refutation or answering. It must also limit the rule set to rules useful for query processing.
955470
Improved Data Retrieval Using Semantic Transformation
Semantic query optimisation uses knowledge about properties of the data, represented as a set of subset descriptor rules, to transform a query into another form that can be executed in a more efficient manner but still yields the same result as the original query. Commonly this ’semantic knowledge’ in the form of rules is generated either during the query process itself or else is constructed in advance according to defined heuristics. Over a period of time the rule set may, therefore, become very large and the number of semantically equivalent queries that may be derived rises exponentially. Each rule use creates a new equivalent query. The problem is to identify one near optimal alternative query in a time that is minimal and also short relative to the overall query execution time. In this paper we propose a method for measuring the effectiveness of each rule and present a fast algorithm which selects the most cost effective transformations to directly yield the optimal alternative query. Experiments carried out on a large publicly available dataset show worthwhile savings using the approach.