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Term
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Description
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Capacity
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The throughput, output, or production of the system while the system is in a specified state.
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Cost
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The gain or loss per unit time based on the specified capacity. Each state and the transitions between states can have a cost associated with them. The cost associated with a state is proportional to its performance level as well as the time spent in that state. This is modeled using the cost per unit time. The cost can also be a loss. Because losses can be different for different failures, this can be modeled using the cost per each state visit. Because repair is a departure from a failed state, repair costs can be modeled using a cost per each departure.
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Degraded state
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A degraded state is used to model levels of performance degradation, which means that they can be used to specify multistate systems. A multiple failure mode system is a special case of a multistate system. The required capacity for a degraded state is specified by entering a value between 0 and 100. When the capacity for this state is less than the specified required capacity, the state is considered to be failed When the capacity for this state is equal to or greater than the specified required capacity, the state is considered to be good.
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End state
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The end state generally represents the state where the equipment is totally unserviceable. There may be multiple end states in a diagram.
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Failed state
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A failed state exists when its capacity is less than its specified required capacity. You can explicitly define a state as a failed state by specifying a capacity of 0. A failed state can also exist for a state that is defined as degraded. When a required capacity between 0 and 100 is specified for a degraded state, the state is considered a failed state if its capacity is less than its specified required capacity. For example, if the required capacity specified for a degraded state is 80 and its capacity is 60, the state is considered to be failed.
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Good state
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A good state exists when its capacity is equal to or greater than its specified required capacity. You can explicitly define a state as a good state by specifying a capacity of 100. A good state can also exist for a state defined as degraded. When a capacity between 0 and 100 is specified for a degraded state, the state is considered a good state if its capacity is equal to or greater than its specified required capacity. For example, if the required capacity specified for a degraded state is 80 and its capacity is 85, the state is considered to be good.
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Initial state
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The initial state represents the initial state of the system, and it is usually where all equipment is operational. There may be more than one initial state in a diagram. A bold arrow points to an initial state.
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Required capacity
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A multistate system can operate or perform at multiple degradation levels. The level of degradation can be specified in terms of required capacity. This means that for a particular operation, a certain level of system capacity is necessary. This level is the required capacity and is used during calculations to determine whether a degraded state should be classified as a good state or a failed state.
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State
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The objects in the Markov diagram that represent the good, failed, and degraded states of the system.
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Transitions
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The connections between states in the Markov diagram, which are assigned failure or repair rates as transition rates.
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