Reliability improvement of electronic circuits based on physical failure mechanisms in components

Traditionally the position of reliability analysis in the design and production process of electronic circuits is a position of reliability verification. A completed design is checked on reliability aspects and either rejected or accepted for production. This paper describes a method to model physical failure mechanisms within components in such a way that they can be used for reliability optimization, not after, but during the early phase of the design process. Furthermore a prototype of a CAD software tool is described, which can highlight components likely to fail and automatically adjust circuit parameters to improve product reliability

Nondestructive testing of microtab welds

Introduction of sinusoidal signal across welded structure to determine reliability of integrated circuit connections is discussed. In-phase frequencies and quadrature frequency functions are used to evaluate weld reliability. Schematic diagram of test equipment and components is provided

Sensitivity Analysis for a Scenario-Based Reliability Prediction Model

As a popular means for capturing behavioural requirements, scenariosshow how components interact to provide system-level functionality.If component reliability information is available, scenarioscan be used to perform early system reliability assessment. Inprevious work we presented an automated approach for predictingsoftware system reliability that extends a scenario specificationto model (1) the probability of component failure, and (2) scenariotransition probabilities. Probabilistic behaviour models ofthe system are then synthesized from the extended scenario specification.From the system behaviour model, reliability predictioncan be computed. This paper complements our previous work andpresents a sensitivity analysis that supports reasoning about howcomponent reliability and usage profiles impact on the overall systemreliability. For this purpose, we present how the system reliabilityvaries as a function of the components reliabilities and thescenario transition probabilities. Taking into account the concurrentnature of component-based software systems, we also analysethe effect of implied scenarios prevention into the sensitivity analysisof our reliability prediction technique

An overview of fatigue failures at the Rocky Flats Wind System Test Center

Potential small wind energy conversion (SWECS) design problems were identified to improve product quality and reliability. Mass produced components such as gearboxes, generators, bearings, etc., are generally reliable due to their widespread uniform use in other industries. The likelihood of failure increases, though, in the interfacing of these components and in SWECS components designed for a specific system use. Problems relating to the structural integrity of such components are discussed and analyzed with techniques currently used in quality assurance programs in other manufacturing industries

User's guide to the Reliability Estimation System Testbed (REST)

The Reliability Estimation System Testbed is an X-window based reliability modeling tool that was created to explore the use of the Reliability Modeling Language (RML). RML was defined to support several reliability analysis techniques including modularization, graphical representation, Failure Mode Effects Simulation (FMES), and parallel processing. These techniques are most useful in modeling large systems. Using modularization, an analyst can create reliability models for individual system components. The modules can be tested separately and then combined to compute the total system reliability. Because a one-to-one relationship can be established between system components and the reliability modules, a graphical user interface may be used to describe the system model. RML was designed to permit message passing between modules. This feature enables reliability modeling based on a run time simulation of the system wide effects of a component's failure modes. The use of failure modes effects simulation enhances the analyst's ability to correctly express system behavior when using the modularization approach to reliability modeling. To alleviate the computation bottleneck often found in large reliability models, REST was designed to take advantage of parallel processing on hypercube processors

Establishing the Reliability and Accuracy of Data Collection for the FIFA 11+ Pre-Participation Study

The FIFA 11+ Pre-Participation study at the University of Vermont is investigating the impact that FIFA 11+ has on injuries to high school athletes. The FIFA 11+ Pre-Participation program has been shown to reduce the incidence of lower extremity injury in elite soccer athletes; however, it is unclear if the program has a similar effect on developing high school athletes or if it can reduce injury in other sports. Recognizing that an athletes’ compliance with the FIFA 11+ program may be directly linked to the effectiveness of the program, an outcome measure that documented compliance was developed. The outcome measure that was developed was a form designed to record pre-participation components of a warm-up by observers for the FIFA 11+ study. The objective of this investigation was to establish the intrarater and interrater reliability and accuracy of this compliance outcome measure. A repeated-measures study design was used to determine the reliability and accuracy of the outcome measure. The examiners who collected data for the FIFA 11+ study were asked to volunteer for this investigation, which involved attending two observation sessions that were two weeks apart. The observation sessions involved watching five warm-up videos, each one about ten minutes long, and then recording what occurred in the warm-up. They used the outcome measure to record their observations of the same five pre-participation warm-ups during each session. The outcome measure had 66 warm-up exercises, or components, that could be recorded. Intraclass Correlation Coefficients (ICCs) were used to determine the intrarater and interrater reliability for each component of the outcome measure. A component with an ICC above 0.60 was considered reliable for this study. The sensitivity and specificity of each component, as well as percent agreement of the examiners with the gold standard examiner for each component were used to determine the accuracy. A component was accurate if above 60% of the observations were in agreement with the gold standard examiner that the component either was or was not present in the warm-up. If any components were proven unreliable or inaccurate the outcome measure was simplified by reducing the number of components. The new components, which were each a result of combining two unreliable components, had ICCs, sensitivity and specificity recalculated as if all observations of either of the original components counted toward the new component. The outcome measure was established to be partially reliable and partially accurate. Out of the 34 components observed there were five components that were intrarater unreliable and 18 components that were interrater unreliable. All of the components that were intrarater unreliable were also interrater unreliable. Only one component was inaccurate with 58% of the observations of that component in agreement with the gold standard examiner’s observations. Of the total 18 unreliable components, seven were combined with another component to simplify the outcome measure

An Approach to Using Non Safety-Assured Programmable Components in Modest Integrity Systems

Programmable components (like personal computers or smart devices) can offer considerable benefits in terms of usability and functionality in a safety-related system. However there is a problem in justifying the use of programmable components if the components have not been safety justified to an appropriate integrity (e.g. to SIL 1 of IEC 61508). This paper outlines an approach (called LowSIL) developed in the UK CINIF nuclear industry research programme to justify the use of non safety-assured programmable components in modest integrity systems. This is a seven step approach that can be applied to new systems from an early design stage, or retrospectively to existing systems. The stages comprise: system characterisation, component suitability assessment, failure analysis, failure mitigation, identification of additional defences, identification of safety evidence requirements, and collation and evaluation of evidence. In the case of personal computers, there is supporting guidance on usage constraints, claim limits on reliability, and advice on “locking down” the component to maximise reliability. The approach is demonstrated for an example system. The approach has been applied successfully to a range of safety-related systems used in the nuclear industry