Intelligent shop scheduling for semiconductor manufacturing

Semiconductor market sales have expanded massively to more than 200 billion dollars annually accompanied by increased pressure on the manufacturers to provide higher quality products at lower cost to remain competitive. Scheduling of semiconductor manufacturing is one of the keys to increasing productivity, however the complexity of manufacturing high capacity semiconductor devices and the cost considerations mean that it is impossible to experiment within the facility. There is an immense need for effective decision support models, characterizing and analyzing the manufacturing process, allowing the effect of changes in the production environment to be predicted in order to increase utilization and enhance system performance. Although many simulation models have been developed within semiconductor manufacturing very little research on the simulation of the photolithography process has been reported even though semiconductor manufacturers have recognized that the scheduling of photolithography is one of the most important and challenging tasks due to complex nature of the process. Traditional scheduling techniques and existing approaches show some benefits for solving small and medium sized, straightforward scheduling problems. However, they have had limited success in solving complex scheduling problems with stochastic elements in an economic timeframe. This thesis presents a new methodology combining advanced solution approaches such as simulation, artificial intelligence, system modeling and Taguchi methods, to schedule a photolithography toolset. A new structured approach was developed to effectively support building the simulation models. A single tool and complete toolset model were developed using this approach and shown to have less than 4% deviation from actual production values. The use of an intelligent scheduling agent for the toolset model shows an average of 15% improvement in simulated throughput time and is currently in use for scheduling the photolithography toolset in a manufacturing plant

Develop specifications for knowledge worker system, version 1.0

Issued as Monthly progress reports [nos. 1-2], Monthly status reports [nos. 1-7], and Reports [nos. 1-6], Project D-48-61

Virtual reality in the rehabilitation of people with intellectual disabilities

Virtual reality (VR) possesses many qualities that give it rehabilitative potential for people with intellectual disabilities, both as an intervention and an assessment. It can provide a safe setting in which to practice skills that might carry too many risks in the real world. Unlike human tutors, computers are infinitely patient and consistent. Virtual worlds can be manipulated in ways the real world cannot be and can convey concepts without the use of language or other symbol systems. Published applications for this client group have all been as rehabilitative interventions. These are described in three groups: promoting skills for independent living, enhancing cognitive performance, and improving social skills. Five groups of studies are reviewed that utilize virtual technology to promote skills for independent living: grocery shopping, preparing food, orientation, road safety, and manufacturing skills. Fears that skills or habits learnt in a virtual setting would not transfer to the real world setting have not been supported by the available evidence, apart from those studies with people with autistic spectrum disorders. Future directions are in the development of more applications for independent living skills, exploring interventions for promoting motor and cognitive skills, and the developments of ecologically valid forms of assessment

A Case Study of Methodist Evangelical Hospital, Louisville, Kentucky and a Blueprint of a Successful Hospital Volunteer Program

A thesis presented to the faculty of the Humanities School at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts in Communications by Amy Elizabeth Lively on April 1, 198

Atmosphere, Magnetosphere and Plasmas in Space (AMPS). Spacelab payload definition study. Volume 7, book 2: AMPS phase C/D analysis and planning document

The results are presented of the AMPS Phase C/D (Design, Development, and Operations) program analysis and planning effort. Cost and schedule estimates are included. Although the AMPS program has been specifically addressed, these task descriptions are basically adaptable to a broader-based program incorporating additional or different Spacelab/orbiter payloads

Performance evaluation and sequence control of an automatedmanufacturing system

In an automated sequential manufacturing system Programmable Logic Controllers (PLC) are widely used. As the control specification varies, the control software needs to be rewritten to accommodate the new specification. Since PLC has high flexibility, one can update the current system while it is running thereby making easier implementation. In order to design flexible, reusable and maintainable control software, a good modeling tool is required. Petri nets are such a tool. Which facilitates analysis of behavioral properties, performance evaluation, and systematic construction of discrete event simulators and controllers. In this thesis a system with one robot and five sequential work stations is used as an example of an automated system. To illustrate the Petri net method, performance and other properties of this system are evaluated. The PLC program is also developed for sequence control of the system