Guangyan Zhao

A calculation method for the reliability of a complex k-out-of-n system

In this paper, a complex k-out-of-n system reliability model based on expandable reliability block diagram is established. Moreover, a reliability calculation method is provided for this system. This method can accurately and efficiently forecast and estimate the reliability of product containing such system. Starting from model simplification and combining with minimal path set (MPS) method and improved binary decision diagram (BDD) disjoint algorithm, its very efficient and convenient for engineering application. Finally an example is discussed to describe its calculation process and prove its effectiveness.

A comparison and case studies of electronic product reliability prediction methods based on handbooks

Currently three handbooks: MIL-HDBK-217F, GJB-Z 299C-2006 and Telcordia SR-332 are widely used in the prediction of electronic products, but engineers often face the problem to choose a proper handbook from them. In this paper the comparison and case studies of reliability prediction methods based on these handbooks are conducted. First of all, the history of reliability prediction based on handbooks is introduced, then the theory, prediction process and advantages of these standards are presented. And the reliability of separate power supply board is predicted based on the three standards, including the failure rate of each components and their contribution to the general failure rate of the power supply board. From the analysis results carried out by the three standards, some suggestions for choosing standards are given.

Structure-based system fault behavior modeling method

With increases in system complexity, new characteristics emerge continuously, and public attention is gradually attracted to mechanisms of system faults. Study of fault behavior and fault propagation modes is oriented at further depicting mechanism of fault of complicated system and clarifying the evolution of system fault behavior by reasoning based on propagation models, thus laying the foundation for technologies e.g. system diagnosis and prediction. In the paper, a structure-based system fault behavior modeling method is studied against influence of design of system structure. A structure-based system fault behavior model, entity, is built. Moreover, fault behavior models of basic unit and fault behavior propagation are given in detail, and detailed rules for behavior and fault propagation are given to illustration the procedure of fault propagation in system. We propose SEMOPN (With Select Mechanism Entity Oriented Petri Net) model to describe entities with Petri Nets thought simulation and the procedure of fault propagation is simulated. Reliability is modeled from a brand-new angle. The model can describe laws by which system faults occur and are expressed, effectively providing technical support for system diagnosis and fault monitoring.

Study on constellation per-slot availability

Constellation per-slot availability is an important factor that influences availabilities of constellation and even the whole navigation system. In the paper, firstly, the structure and top parameters of satellite navigation system is studied. Secondly, process of constellation per-slot work is analyzed, which brings per-slot operation profile and single-satellite life profile, and based on the analysis results, per-slot service states are defined and classified. Thirdly, Markov model is proposed for calculating per-slot availability considering the influence of standby satellite on slot availability. Finally, with the actual data about GPS constellation, method for calculating per-slot availability is presented and discussed.

Thermal simulation of stirling cooler in IR system based on Flotherm

Thermal analysis is an important technology for electronics equipment reliability analysis. In recent years, demands of thermal analysis for electromechanical products have been highly increased. In this paper, one electromechanical product, Stirling cooler in IR system, was modeled in thermal analysis software Flotherm used for electronic products. By studying the working principle and physical model of Stirling cooler, heat-affected factors such as inner structure, fluid conduction, heat absorbed and released by the cooler from ambient are analyzed. Approaches to modeling these factors are discussed in this paper, and we achieve the simulation in Flotherm software and verified simulation models by thermal measurement. These modeling methods provide a reference for thermal analysis for electromechanical and other products.

Study on QFD-based primary selection method for test signals

The primary selection of test signals is the foundation of design for testability. However, since the lack of data in the preliminary design phase for testability, it is difficult to quantitatively gain the test signal set with the highest cost-effectiveness ratio through calculation. According to the fact mentioned above, this paper proposes a primary selection method for test signals based on QFD. This method, synthesizing the factors including reliability and testing cost, can qualitatively obtain the importance degree of each test signal by means of the House of Quality (HoQ) and then select the test signals primarily based on the importance degree order, which provides clues for the design of test points.

The qualitative modeling method of fault propagation in electronic components

According to the electronic components in analog circuit, a new qualitative modeling method for the fault propagation in components was presented in this paper. Firstly, the related concepts of fault propagation were introduced based on the existing study. Then, a definition to the fault propagation model of electronic components, named connectivity model, was clarified. Furthermore, the corresponding impact mechanism and the qualitative modeling method of fault propagation were put forward. Finally, the connectivity models of several typical electronic components were established. The proposed qualitative modeling method of components is verified by tests in PSPICE, which provides the foundation of the qualitative modeling and reasoning of fault propagation in circuit systems.

Simulation on missile availability with consideration to storage process

Aimed at the long-term store and one-time use characteristics of missiles, activities of failures, maintenance and support in storage process were simulated to evaluate the missile availability. Missile availability simulation model considering storage process was developed based on the idea of dynamic simulation model for discrete events. Relevant simulation logics were designed, and the task process and fault sampling simulation logics were described in detail. Finally, the comparison was made between two simulation model cases: one considered the storage process and the other did not. The result shows that the simulation module and algorithm are correct. The simulation method of considering the effects of storage on the missile availability are proposed, which can provide technical support for demonstration and evaluation of the missiles indexes of reliability, maintainability and supportability.