Analysis of Alternative Rework Strategies for Printed Wiring Assembly Manufacturing Systems

This paper presents a model for predicting the cost of test, diagnosis, and rework activities in the manufacture of printed wiring assemblies (PWA's). Rework is defined as all actions taken to correct or improve the basic assembly process. These actions may include those of inspectors and solder touchup technicians who do not add value to the PWA, but whose actions are required in order to produce acceptable yields from the manufacturing process. Two alternative rework strategies for contemporary PWA manufacturing systems are presented: terminal rework and distributed rework. Rework may occur after all assembly operations have been accomplished (terminal rework) or it may be distributed throughout the assembly process. This paper allalyzes the economic basis for deciding between the two rework strategies. The paper assumes that the only reason for utilizing distributed rework is to reduce the cost of producing acceptable PWA's, otherwise the cost of the distributed rework effort cannot be justified. The paper presents a model of each rework strategy. The effect of each strategy upon first pass yield (FPY) of the manufacturing process is discussed. The effect on FPY is then used to evaluate the economic benefit of each rework strategy as an aid in deciding which strategy to use. The increase in FPY needed to justify distributed rework is calculated

Integrated control and health management. Orbit transfer rocket engine technology program

To insure controllability of the baseline design for a 7500 pound thrust, 10:1 throttleable, dual expanded cycle, Hydrogen-Oxygen, orbit transfer rocket engine, an Integrated Controls and Health Monitoring concept was developed. This included: (1) Dynamic engine simulations using a TUTSIM derived computer code; (2) analysis of various control methods; (3) Failure Modes Analysis to identify critical sensors; (4) Survey of applicable sensors technology; and, (5) Study of Health Monitoring philosophies. The engine design was found to be controllable over the full throttling range by using 13 valves, including an oxygen turbine bypass valve to control mixture ratio, and a hydrogen turbine bypass valve, used in conjunction with the oxygen bypass to control thrust. Classic feedback control methods are proposed along with specific requirements for valves, sensors, and the controller. Expanding on the control system, a Health Monitoring system is proposed including suggested computing methods and the following recommended sensors: (1) Fiber optic and silicon bearing deflectometers; (2) Capacitive shaft displacement sensors; and (3) Hot spot thermocouple arrays. Further work is needed to refine and verify the dynamic simulations and control algorithms, to advance sensor capabilities, and to develop the Health Monitoring computational methods

Design and implementation for automated network troubleshooting using data mining

The efficient and effective monitoring of mobile networks is vital given the number of users who rely on such networks and the importance of those networks. The purpose of this paper is to present a monitoring scheme for mobile networks based on the use of rules and decision tree data mining classifiers to upgrade fault detection and handling. The goal is to have optimisation rules that improve anomaly detection. In addition, a monitoring scheme that relies on Bayesian classifiers was also implemented for the purpose of fault isolation and localisation. The data mining techniques described in this paper are intended to allow a system to be trained to actually learn network fault rules. The results of the tests that were conducted allowed for the conclusion that the rules were highly effective to improve network troubleshooting.Comment: 19 pages, 7 figures, International Journal of Data Mining & Knowledge Management Process (IJDKP) Vol.5, No.3, May 201

NASA space station automation: AI-based technology review

Research and Development projects in automation for the Space Station are discussed. Artificial Intelligence (AI) based automation technologies are planned to enhance crew safety through reduced need for EVA, increase crew productivity through the reduction of routine operations, increase space station autonomy, and augment space station capability through the use of teleoperation and robotics. AI technology will also be developed for the servicing of satellites at the Space Station, system monitoring and diagnosis, space manufacturing, and the assembly of large space structures