Analyzing Sparing Policy in the Operations of Space Habitats
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Maxwell, Andrew Jones
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Abstract
The inclusion of operational sparing policies in early system definition can ensure that spares allocations can optimally meet desired system reliabilities consistent with the planned maintenance of a crewed vehicle. This approach is critical for long-duration crewed missions where mass allocations are constrained and lack of safe abort contingencies limit options in the event of significant system degradation, especially in the environmental and life support systems. The research presents both simulation-based and analytical approaches to identify optimal spares allocations for various sparing policies.
The developed simulation method improves a current state-of-the-art tool from two perspectives. First, it develops a new method based on the modified knapsack problem to generate the spares allocations that maximize the probability of sufficiency given a mass capacity. Additionally, it develops a simulation model with a failure queue to enhance the flexibility of the state-of-the-art model to evaluate different sparing policies. With the developed method, comparative studies using two allocation approaches and two different policies are presented.
The research also presents an analytical model for analyzing and optimizing sparing policies as part of an overall evaluation of the probability of sufficiency for a system configuration. The repair transition parameters are varied to change the state visitation probabilities which drive a change in the probability of sufficiency observed for a given mass allocation. These parameters are optimized using a particle swarm optimizer to identify the preferred strategy for a desired allocation mass.
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Date
2023-05-08
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Dissertation