Availability of multi-state systems subject to hard and soft failures



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Texas Tech University


Many different types of systems experience states of complete availability, partial availability and unavailability. For example, automobiles are designed to perform in a manner such that the highest posted speed limit may be met or exceeded. However, it is possible for some malfunction to occur which will not allow the automobile to meet the posted speed limit, but the automobile may be capable of performance at some lower speed. Although the automobile will not perform at the level for which it was designed to perform, the reduced level of performance does enable the operator to proceed to a location where the automobile may be repaired. Many other automotive systems/subsystems manifest a similar behavior. For example, a heater or air condition may fail to operate while the remaining subsystems operate completely. Although the automobile does not completely operate as designed, there is some reduced level of operation and the system is partially available. When the automobile completely ceases to operate, the system is unavailable.