Reliability improvement is a major goal in many applications. It is especially vital in sensitive devices where human life is involved such as medical electronic systems as well as military applications. The reliability of the analog computer of the naval navigation system was improved by the application of derating and accelerated life testing. Spice circuit analysis and temperature profile analysis were performed based on which part derating scheme was developed. Afterwards a systematic approach for accelerated life testing was designed to discover the weaknesses of the system under test and the fixes to the system were performed to improve its reliability. Since many mechanisms of failure were present in the product being tested, the PMRL model was used for multiple failure modes in modeling the failure times obtained from accelerated life tests. A significant reduction in mean time to failure and improvement in reliability was achieved. The predictive calculations for the mean time to failures were carried out using MIL-HDBK-217F for the Naval Sheltered and the Naval Unsheltered working conditions per the real operating conditions of the system and were compared with the results obtained from our experimental and modeling work.

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