Last modified: 2015-07-20
Abstract
The reliability optimization has achieved great concern in recent years. Nowadays, many researchers obtain allocation results which can maximize the system reliability subject to the system budget. In these researches, the effect of system’s functions is always neglected or only considering the single main function of system. In addition, there are also not obvious evidences in results to distinguish the importance level of different units. However, complex systems tend to perform multiple functions. What’s more, the use frequency of each function and the combinations of units to realize different function is not the same. In addition, the use demand of different function is decided by different task environment, the demand differentiation of functions has led to the use frequency of various functions should have different levels about reliability. Therefore, the reliability optimization allocation that only considering cost constraint conditions is not accuracy and will results in disaccord between the obtained results with actual situation.
Focusing on the problem mentioned above, a reliability optimization allocation method that considering cost constraint and importance factor is proposed. In this paper we consider systems consisting of units characterized by different reliability and importance factors. Such systems are multi-function because they must perform different tasks depending on the combination of units. Different functions may be work simultaneously. Firstly, the concept of importance factor is defined to describe the importance of a unit and the required importance factor level of system functions in the task is also given. To deal with the differentiation of system functions, the corresponding bound about importance factor are executed when looking for the optimal solution. Similarly, the cost constraint is also forced. Finally, in order to reduce the randomness of intelligent algorithm, a number of optimization are conducted and a rule is proposed to select the most optimal solution from all the optimal solutions which are obtained in every iterative loop.
Example of the comprehensive transmission equipment is presented. To begin with, we establish the reliability function of system as the objective optimization function. Then, the restraint of budget and different demands of importance factor of system functions are posed. Furthermore, using a genetic algorithm as the optimization tool, the optimization result can be obtained. Finally, the most optimal solution is selected. The results show that the method we proposed is more correct and more approximate the reality.
The reliability optimization allocation method presented in this paper can not only consider the constraint of cost, but also can consider the diversities of functions, and thus the optimization results will more approximate actual situation. At the same time, this paper can also provide guidance for the similar reliability optimization problem.