Markov process to determine reliablity of parallel system for different units

It is quite often to use many identical units in parallel in actual engineering to improve the reliability of the system .In fact all the units have different reliability parameters ,it is therefore a system with defferent units in parallel.Markov process is used to analyze different working orders and repair failure rates,and changes in both working orders and repar failure states for different units in parallel .Based upon the exponential distribution of life span and repair time,the law of different dimensional states and reciprocal motions is used to obtain the reliability parameters for different units in parallel.Experimental results proved this method is effective and practicable. 