In brief these tasks include developing and executing

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Unformatted text preview: the U.S. Nuclear Regulatory Commission Fault Tree Handbook. NASA Systems Engineering Handbook Integrating Engineering Specialties Into the Systems Engineering Process Reliability Models. Reliability models are used to predict the reliability of alternative architectures/designs from the estimated reliability of each component. For simple systems, reliability can often be calculated by applying the rules of probability to the various components and "strings" identified in the reliability block diagram. (See Figure 29.) For more complex systems, the method of minimal cut sets, which relies on the rules of Boolean algebra, is often used to evaluate a system's fault tree. When individual component reliability functions are themselves uncertain, Monte Carlo simulation methods may be appropriate. These methods are described in reliability engineering textbooks, and software for calculating reliability is widely available. For a compilation of models/software, see D. Kececioglu, Reliability, Availability, and Maintainability Software Handbook. FMECAs and FMEAs. Failure Modes, Effects, and Criticality Analysis (FMECA) and Failure Modes and Effects Analysis (FMEA) are specialized techniques for hardware failure and safety risk identification and characterization. (Also see Section 4.6.2.) Problem/Failure Reports (P/ FRs). The reliability engineer uses the Problem/Failure Reporting System (or an approved equivalent) to report reliability problems and nonconformances encountered during qualification and acceptance testing (Phase D) and operations (Phase E). 6.3 Quality Assurance Even with the best of available designs, hardware fabrication (and software coding) and testing are subject to the vagaries of Nature and human beings. The system engineer needs to have some confidence that the system actually produced and delivered is in accordance with its functional, performance, and design requirements. Quality Assurance (QA) provides an independent assessment to the project manager/system engineer of the items produced and proce...
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