A condition based preventive and corrective maintenance policy is proposed for a continuously operating system. The condition of the system is assumed to deteriorate with time. The model incorporates both deterioration as well as random common cause failures. The deterioration stages are modeled as discrete state processes. The system is put to random inspection to know the condition. The mean ...

In this research, a model for optimal PM planning based on reliability is developed and solved for multi-component systems. In the proposed model, the type of PM actions for each inspection period is determined in such manner that the total weighted related costs are minimized while a minimum required system reliability is maintained. The planning horizon is divided into some inspections interv...

As aircraft structures begin to age (that is, as flight hours accumulate), existing subcritical cracks or new cracks can grow in some high-stress points of the structural components. The usual approach is to inspect the structures periodically at certain intervals. Thus, a catastrophic accident during flight can be avoided. The problem then arises of choosing a sequence of inspection times whic...

Superrcially, the Earliest Task First (ETF) heuristic 1] is attractive because it models heterogeneous messages passing through a heterogeneous network. On closer inspection, however, this is precisely the set of circumstances that can cause ETF to produce seriously sub-optimal schedules. In this paper we analyze the scope of applicability of ETF. We show that ETF has a good performance if mess...

An optimization-based estimation method is presented for determining mode transition times and model parameters for hybrid systems. Firstand second-order optimality conditions are derived, including cross-derivative terms between transition times and parameters. Second-order optimization methods are shown to provide superior convergence to correct values in simulation, and to values within expe...

The problem of reducing energy consumption is dominating the design and the implementation of embedded realtime systems. For this reason, a new generation of processors allow to vary the voltage and the operating frequency to balance computational speed versus energy consumption. The policies that can exploit this feature are called Dynamic Voltage Scheduling (DVS). In real-time systems, the DV...