Evaluating the significance of system parameters with uncertain methods and its application

It is important to evaluate the significance of system parameters in engineering, especially for reducing the dimension and complexity of system. The rough sets theory is introduced into evaluation the significance of system. A parameter defined by the concepts of lower and upper approximation in rough sets theory is used to estimate the significance of system parameters. The proposed method in the article is applied in fault analysis of diesel engine´s plunger and the result matches the practical one. We can get more information of the system by this method comparing with the other methods, such as K-W method and method based on information entropy.