In this paper, the optimal maintenance policy for a multi-state system with no observation is considered. Different from most existing works, only a limited number of imperfect preventive maintenance actions can be performed between two successive replacements. Assume that the system's deterioration state cannot be observed during its operation expected after each replacement, and it evolves as a discrete-time Markov chain with a finite state space. After choosing the information state as state variable, the problem is then formulated as a Markov decision process over the infinite time horizon. In order to increase the computational efficiency, several key structural properties are developed by minimising the total expected cost per unit time. The existence of the optimal threshold-type maintenance policy is proved and the monotonicity of the threshold is obtained. Finally, a numerical example is given to illustrate the optimal policy.
Abstract:The present work is about the dynamic model and the experimental testing of the magnetorheological fluid(MRF) mounts, especially at wide frequency. A squeeze MRF mounts is adopted, according to Bingham model, the react force of the mounts is divided to three parts which contains coulomb damping force, viscous damping force and elastic force. An advanced polynomial Bingham parameterization model is built by analysing the relationship between the frequency, magnetic field and the each part force.The applied current and the excitation frequency in this model as variable, nine variable parameters of the second order polynomial are found by testing different operating conditions. A verification test shows the reliability and the performance of the proposed model.
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