<p>This thesis deals with the reliability and life-time ofelectronic components and ways to determine these factors.Plastic encapsulated and open test circuits were assessed atdifferent humidity and temperature conditions. From the resultsan acceleration factor could be derived using the Arrheniusrelation. This factor is used to determine failure rates atdifferent drift conditions under accelerated test conditions. Aformula for the factor containing both relative humidity andtemperature could be established and was found to hold also formeasurements published by others.</p><p>Electrostatic discharge (ESD) transients were studiedexperimentally and by simulation with good agreement. A verysensitive method to detect latent failures of two kinds wasintroduced by nonlinearity measurements utilizing the thirdharmonic of a test signal. The ESD-susceptibility dependence ondesign and technology is shown and can be used to improvebuilt-in reliability.</p><p>Influences in the performance of semiconductor devices fromdefects like fixed charges and ions were interpreted for thefirst time by simulation using a 2D- finite element componentprogram. Significant results gave an application to a MOSFETdevice showing parameter derating, especially the change of thethreshold value. A short description of later development insimulation methods with new, more powerful tools improvingcomponent performance and reliability is given.</p><p>Charged thin films of Teflon, so called<i>electrets</i>, are used as microphone membranes. Theelectret voltage is a suitable reliability factor. Fromexperimental results a mathematical relation including thetemperature was established for the rate of decay of theelectret voltage with time. A method to charge the electretswith radioactive sources is outlined and described in apatent.</p><p>Finally an attempt was done to analyze the reliability ofthin film circuits by mathematical methods. Bell Labsintroduced<i>RC</i>-feedback filters realized in tantalum thin filmtechnology. The phase shift of the filter is about π or180°. A mathematical apparatus was developed to calculatethe change in frequency and attenuation from small componentvariations in resistors and capacitors. First and higher ordercorrections were derived, using expansion by the Taylor seriesfor the higher order.</p><p><b>Keywords:</b>reliability, failure mechanism, accelerationtests, ESD, latent failure, plastic encapsulation, electret,thin film</p>

Designing high-integrity socio-technical systems requires a thorough understanding of all safety risks of such systems. For many years, safety risk assessment has been conducted separately for hardware, software, human, organizational and other entities in socio-technical systems. Safety risk assessment that does not consider all factors at the same time cannot adequately capture the wide variety of safety risk scenarios that need to be considered. This thesis proposes a model-based analysis approach that allows interpretation of humans and organizations in terms of components and their behavior in terms of failure logic. The proposal is built on top of the tool-supported model-based failure logic analysis technique called CHESS-FLA. CHESS-FLA supports the analysis of the component-based system architectures to understand what can go wrong at a system level, by applying failure logic rules at a component level. CHESS-FLA addresses only hardware and software components and as such it is inadequate for the analysis of socio-technical systems. This thesis proposes an extension of CHESS-FLA based on the preexisting classification (developed within SERA), of failures of socio entities. This extension combines CHESS-FLA and SERA - classification and delivers an approach named Concerto-FLA. Concerto-FLA is fully integrated into the CONCERTO framework allowing an automated analysis to be performed on architectures that contain human, organizational and technical entities present in socio-technical systems. The use of the approach is demonstrated on a case study extracted from the petroleum domain. The effectiveness of the delivered tool is briefly evaluated based on the results from the case study. / CONCERTO project

No description available.

A learning effect has been shown to be present in the repeated performance of the six-minute walk test and contributes to the variability of walk distance up to the third walk test. The purpose of this study was to see if education about the performance of the walk test could minimize the learning effect. It was hypothesized that education about the learning effect would decrease the learning effect. There were a total of 18 subjects (5 female and 13 male) with a mean age of 63.7+12.1 years that completed three standardized six-minute walk tests. The subjects were randomly assigned to either a Learning Effect Education (LEE) group or a Usual Care (UC) group. The LEE group was provided with education material about the learning effect approximately two days prior to their first walk test, with additional instruction immediately prior to their first walk test. The mean walk distances for the LEE group over the three walk tests were 1,248±297.4, 1,361.9±275.7, and 1,355.1+291.7 feet, respectively. Mean walk distances for the UC group over the three walk tests were 1,149.6+392.3, 1,123.6+427.5, and 1,209.9±368.7 feet, respectively. The hypothesis was tested and the repeated measures ANOVA showed a significant (p=0.033) interaction between the groups with respect to six-minute walk distance. A Bonferroni's post hoc analysis showed that mean walk distance (113.9+42.3 feet) increased significantly (p=0.048) from test one to test two in the LEE group. There was no significant difference between mean walk distance from test two and test three (6.8+31.1 feet) in the LEE group. In the UC group, there was no significant increase in mean walk distance from test one to test two (-26+42.3 feet), while there was a significant (p=0.04) increase in mean walk distance from test two to test three (86.3+31.1 feet). There was a significant difference between walk tests (p=0.011) with no significant difference between groups (p=0.333). In conclusion, the results from this study suggest that education may reduce the number of familiarization trials needed prior obtaining an accurate baseline six-minute walk test distance. / School of Physical Education

The maintenance of equipment has been an important issue for companies for many years. For systems with hidden or unrevealed failures (i.e., failures are not self-announcing), a common practice is to regularly inspect the system looking for such failures. Examples of these systems include protective devices, emergency devices, standby units, underwater devices etc. If no periodical inspection is scheduled, and a hidden failure has already occurred, severe consequences may result. Research on periodical inspection seeks to establish the optimal inspection interval (Failure Finding Interval) of systems to maximize availability and/or minimize expected cost. Research also focuses on important system parameters such as unavailability. Most research in this area considers non-negligible downtime due to repair/replacement but ignores the downtime caused by inspections. In many situations, however, inspection time is non-negligible. We address this gap by proposing an optimal failure finding interval (FFI) considering both non-negligible inspection time and repair/replacement time. A novel feature of this work is the development of models for both age-based and calendar-based inspection policies with random/constant inspection time and random/constant repair/replacement time. More specifically, we first study instantaneous availability for constant inspection and repair/replacement times. We start with the assumption of renewal of the system at each inspection. We then consider models with the assumption of renewal only after failure. We also develop limiting average availability models for random inspection and repair/replacement times, considering both age-based and calendar-based inspection policies. We optimize these availability models to obtain an optimal FFI in order to maximize the system’s availability. Finally, we develop several cost models for both age-based and calendar-based inspection policies with random inspection time and repair/replacement time. We formulate the model for constant inspection time and repair/replacement time as a special case. We investigate the optimization of cost models for each case to obtain optimal FFI in order to minimize the expected cost. The numerical examples and case study presented in the dissertation demonstrate the importance of considering non-negligible downtime due to inspection.

The maintenance of equipment has been an important issue for companies for many years. For systems with hidden or unrevealed failures (i.e., failures are not self-announcing), a common practice is to regularly inspect the system looking for such failures. Examples of these systems include protective devices, emergency devices, standby units, underwater devices etc. If no periodical inspection is scheduled, and a hidden failure has already occurred, severe consequences may result. Research on periodical inspection seeks to establish the optimal inspection interval (Failure Finding Interval) of systems to maximize availability and/or minimize expected cost. Research also focuses on important system parameters such as unavailability. Most research in this area considers non-negligible downtime due to repair/replacement but ignores the downtime caused by inspections. In many situations, however, inspection time is non-negligible. We address this gap by proposing an optimal failure finding interval (FFI) considering both non-negligible inspection time and repair/replacement time. A novel feature of this work is the development of models for both age-based and calendar-based inspection policies with random/constant inspection time and random/constant repair/replacement time. More specifically, we first study instantaneous availability for constant inspection and repair/replacement times. We start with the assumption of renewal of the system at each inspection. We then consider models with the assumption of renewal only after failure. We also develop limiting average availability models for random inspection and repair/replacement times, considering both age-based and calendar-based inspection policies. We optimize these availability models to obtain an optimal FFI in order to maximize the system’s availability. Finally, we develop several cost models for both age-based and calendar-based inspection policies with random inspection time and repair/replacement time. We formulate the model for constant inspection time and repair/replacement time as a special case. We investigate the optimization of cost models for each case to obtain optimal FFI in order to minimize the expected cost. The numerical examples and case study presented in the dissertation demonstrate the importance of considering non-negligible downtime due to inspection.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Economics. / Typescript. Includes bibliographical references (leaves 141-151). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://proquest.umi.com/pqdweb?index=0&did=1251858901&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1195140742&clientId=5220

Thesis (M.H.S.A.)--University of Michigan, 1976.

Thesis (M.H.S.A.)--University of Michigan, 1976.

M.Ed. (Educational Psychology) / Please refer to full text to view abstract