Yang Zhiming

Design of Fault Diagnosis System Based on B/S Structure

With the wide application of modern electrical technique to weapon systems, weapons become more and more complicated, integrated, high-speed and intellectualized. To insure weapons in their good conditions, the function of fault diagnosis gets more important than before in the process of repairing. Now, it cannot give fault diagnosis quickly and correctly only by conventional means. So developing proper system is in need. This paper designed and developed a network fault diagnosis system based on B/S (Browser/Server) frame through the analysis of the need of fault diagnosis. Taking good use of testing information and diagnosis rules, the system realized open and distributed diagnosing process, and provided a flat of sharing information, which is the technique basis of combining testing and diagnosing. During design, we use Macromedia Dreamweaver MX 2004 as developing software and Java Scripts and VB Scripts in ASP language as scripts to program. It is proved in LAN that the system can utilize present diagnosis rules in database to diagnose fault distributed. Besides, the system is stable with expansibility and security.

Graph-based fault diagnosis method for complex electronic systems

An efficient graph-based method to analyze fault propagation characteristics in the complex electronic systems is proposed. Firstly, two test node selection methods are proposed to meet different level of diagnosis requirements, and a greedy algorithm is applied to find the best test nodes. Then, a fault propagation characteristics analysis model based on hierarchical signed directed graph is established, which combines the systems hierarchical topology structure information into model, so that it can describe the propagation characteristics more accurately and clearly. The established model can analyze fault propagation characteristics and find the fault root cause efficiently. Experimental result on an actual satellite central control system shows that, compared with traditional SDG, the fault propagation model proposed in this paper can shrink fault location searching area and shorten fault diagnosis time cost. Besides, the structure of established model is closer to the structure of real system and the reasoning process is easier to explain, which makes it more suitable to solve the fault propagation analysis and fault location tasks for complex electronic systems.

Electronic circuit fault diagnosis methods based on improved Support Vector Machines

In nowadays, fault diagnosis method for analog circuit based on support vector machines, has become a hot topic in research field of fault diagnosis. However, in practical application of this method, the imbalanced problem occurred in fault sample dataset has greatly influenced its effectiveness. To remedy this problem, this paper proposed an improved Support Vector Machines method based on biased empirical feature mapping. In the new method, biased discriminant analysis was applied in empirical feature space, to make all normal samples far away from center of fault samples, so that the overall fault diagnosis ability can be improved. Through theoretical analysis and empirical study on actual electronic circuit fault diagnosis problem, we show that our method augments the diagnosis accuracy rate effectively.