Fault Diagnosis Method Based on System-phenomenon-fault Tree

The historical records of mechanical fault contain great amount of important information which is useful to identify the similar fault.The current fault diagnosis methods using historical records are inefficient to deal with intuitive application and multicomponent multiphase fault diagnosis.Towards the problem,the rapid and intelligent fault diagnosis method based on system-phenomenon-fault （SPF） tree is proposed.The method begins with the physical system of the fault system,conceives the fault causes as leaves,the fault causes as leaves and the frequentness of fault as the interrelationship,and finally forms the fault tree with structural relationship of administrative subordination and flexible multi-granularity components.Firstly,the forming method of SPF tree is discussed;Secondly some basic definitions as synonymous branch,the tough degree of the branch,the dominant leaf,and the virtual branch are defined;and then,the performances including the merger of the dominant branches keeping dominant,the merger of the synonymous branches keeping dominant were proved.Furthermore,the merging,optimizing and calculating of virtual branch of SPF tree are proposed,the self-learning mechanism including the procedure and the related parameter calculation is presented,and the fault searching method and main fault statistics calculation are also presented based on SPF tree.Finally,the method is applied in the fault diagnosis of the certain type of embedded terminal to demonstrate fault information searching in the condition of the synonymous branch,the virtual branch merging and visual presentation of search results.The application shows that the proposed method is effective to narrow down the scope of searching fault and reduce the difficulty of computing.The proposed method is a new way to resolve the intelligent fault diagnosis problem of complex systems by organizing the disordering fault records and providing intuitive expression and intelligent computing capabilities.

Application of Attribute Reduction to Well Logging

The quantity of well logging data is increasing exponentially, hence methods of extracting the useful information or attribution from the logging database are becoming very important in logging interpretation. So, the method of logging attribute reduction is presented based on a rough set, i.e., first determining the core of the information table, then calculating the significance of each attribute, and finally obtaining the relative reduction table. The application result shows that the method of attribute reduction is feasible and can be used for optimizing logging attributes, and decreasing redundant logging information to a great extent.

On new measurement and communication techniques of GNSS inter-satellite links

This paper studies the key techniques of the measurement and communication system for inter-satellite links(ISLs) of global navigation satellite system.A fixed link topology is designed based on the analysis of inter-satellite geometric properties and spatial parameters of the standard Walker24/3/2 constellation.This design can achieve full network coverage with small num-ber of hops,significantly reduce the number of ISLs,and enhance the feasibility and reliability of the system.A new time-division duplex mode,as well as an integrated measurement and communication scheme,is proposed based on the de-signed topology.Furthermore,mathematical formulas,error models,and modification methods regarding two-way ranging and time synchronization algorithms using spread spectrum non-coherent data frame for this new system are comprehensively dis-cussed.Theoretical analysis and simulation studies demonstrate that our design,compared with current GPS systems,has higher ranging and time synchronization precision,improved measurement efficiency,and higher channel utilization ratio and data transmission rate.It has no restrictions of constellation configuration,making it suitable for both MEO and the future MEO/GEO hybrid constellations.The results in this paper can serve as strong technical support for the next generation of GNSS ISL.

Round-trip imaging through scattering media based on optical transmission matrix

Traditional one-way imaging methods become invalid when a target object is completely hidden behind scattering media. In this case, it has been much more challenging, since the light wave is distorted twice.To solve this problem, we propose an imaging method, so-called round-trip imaging, based on the optical transmission matrix of the scattering medium. We show that the object can be recovered directly from the distorted output wave, where no scanning is required during the imaging process. We predict that this method might improve the imaging speed and have potential application for real-time imaging.