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A hazard analysis via an improved timed colored petri net with time–space coupling safety constraint

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Chinese Journal of Aeronautics 2016年第4期29卷 1027-1041页

作者： Li Zelin Wang Shihai Zhao Tingdi Liu Bin science and technology on reliability and environmental engineering laboratory School of Reliability and Systems Engineering Beihang University

Petri nets are graphical and mathematical tools that are applicable to many systems for modeling, simulation, and analysis. With the emergence of the concept of partitioning in time and space domains proposed in avionics application standard software interface (ARINC 653), it has become difficult to analyze time–space coupling hazards resulting from resource partitioning using classical or advanced Petri nets. In this paper, we propose a time–space coupling safety constraint and an improved timed colored Petri net with imposed time–space coupling safety constraints (TCCP-NET) to fill this requirement gap. Time–space coupling hazard analysis is conducted in three steps: specification modeling, simulation execution, and results analysis. A TCCP-NET is employed to model and analyze integrated modular avionics (IMA), a real-time, safety-critical system. The analysis results are used to verify whether there exist time–space coupling hazards at runtime. The method we propose demonstrates superior modeling of safety-critical real-time systems as it can specify resource allocations in both time and space domains. TCCP-NETs can effectively detect underlying time–space coupling hazards. © 2016 Chinese Society of Aeronautics and Astronautics

关键词： Application programs Avionics Hazards Interactive computer systems Petri nets Resource allocation Safety engineering

Comparative study between crack closure model and Willenborg model for fatigue prediction under overload effects

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Chinese Journal of Aeronautics 2016年第6期29卷 1618-1625页

作者： Jiang Shan Zhang Wei He Jingjing Wang Zili science and technology on reliability and environmental engineering laboratory School of Reliability and Systems Engineering Beihang University

A comparative study is performed between a crack closure model and the Willenborg model, which can calculate the fatigue crack growth rate under the overload effects. The modified virtual crack annealing(VCA) model is briefly reviewed, which is based on the equivalent plastic zone concept. In this method, the retardation phenomenon is explained by the crack closure level variation, which is derived from the interactions between forward and reverse plastic zones ahead of the crack tip. As a comparison, the Forman equation in conjunction with the Willenborg model is also reviewed. The retardation phenomenon is described by directly modifying the stress intensity factor. It is known that the large plastic zone created by the overload can decelerate the fatigue crack growth rate until the crack grows beyond this region. A relationship between the plastic zone and the modified stress intensity factor is developed, which is a mathematical fitting equation instead of physical-based formulation. The experimental data in aluminum alloys are used to validate these two models. Overall, good agreement is observed between the model predictions and the testing data. It is noted that the approach based on modified VCA model can give more accurate prediction curves than the Willenborg model.

关键词： Crack closure Fatigue crack growth Interaction effects Overloads Plastic zone

Acceptance sampling plan of accelerated life testing for lognormal distribution under time-censoring

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Chinese Journal of Aeronautics 2015年第3期28卷 814-821页

作者： Li Xiaoyang Gao Pengfei Sun Fuqiang science & technology on reliability & environmental engineering laboratory Beihang Univeristy

Abstract Lognormal distribution is commonly used in engineering. It is also a life distribution of important research values. For long-life products follow this distribution, it is necessary to apply accelerated testing techniques to product demonstration. This paper describes the development of accelerated life testing sampling plans （ALSPs） for lognormal distribution under time-censoring conditions. ALSPs take both producer and consumer risks into account, and they can be designed to work whether acceleration factor （AF） is known or unknown. When AF is known, lift testing is assumed to be conducted under accelerated conditions with time-censoring. The producer and con- sumer risks are satisfied, and the size of test sample and the size of acceptance number arc opti- mized. Then sensitivity analyses are conducted. When AF is unknown, two or more predetermined levels of accelerated stress are used. The sample sizes and sample proportion allo- cated to each stress level are optimized. The acceptance constant that satisfies producer and consumer risk is obtdned by minimizing the generalized asymptotic variance of the test statistics. Finally, the properties of the two ALSPs （one for known-AF conditions and one for unknown AF conditions） are investigated to show that the proposed method is corrcct and usablc through numerical examples.

关键词： Accelerated life testing Acceleration factor Acceptance sampling Lognormal distribution Producer and consumerrisks Time-censoring

Effects of the extrusion parameters on microstructure,texture and room temperature mechanical properties of extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 136-146页

作者： Chenjin Zhang Guangyu Yang Lei Xiao Zhiyong Kan Jing Guo Qiang Li Wanqi Jie State Key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China College of Materials science and engineering Fuzhou UniversityFuzhou 350108China College of Chemistry and environmental science Qujing Normal UniversityQujing 655011China

Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed *** dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)*** the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical-rare-earth(RE)*** alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening *** results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.

关键词： Mg-rare earth alloys extrusion temperature extrusion ratio extrusion speed strengthening mechanisms

reliability modeling of mutual DCFP considering failure physical dependency

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Journal of Systems engineering and Electronics 2023年第4期34卷 1063-1073页

作者： CHEN Ying YANG Tianyu WANG Yanfang science and technology on reliability and environmental engineering laboratory Beihang UniversityBeijing 100191China

Degradation and overstress failures occur in many electronic systems in which the operation load and environmental conditions are *** dependency of them called dependent competing failure process(DCFP),has been widely *** system may experience mutual effects of degradation and shocks,they are considered to be *** the degradation and the shock processes will decrease the limit of system and cause cumulative ***,the competition of hard and soft failure will cause the system *** on the failure mechanism accumulation theory,this paper constructs the shock-degradation acceleration and the threshold descent model,and a system reliability model established by using these two *** mutually DCFP effect of electronic system interaction has been decomposed into physical correlation of failure,including acceleration,accumulation and *** a case,a reliability of electronic system in aeronautical system has been analyzed with the proposed *** method proposed is based on failure physical evaluation,and could provide important reference for quantitative evaluation and design improvement of the newly designed system in case of data deficiency.

关键词： electronic system dependent competing failure process(DCFP) failure physical dependency threshold descent model competition failure modes

reliability evaluation of avionics system with imperfect fault coverage and propagated failure mechanisms

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Chinese Journal of Aeronautics 2020年第12期33卷 3437-3446页

作者： Ying CHEN Song YANG Rui KANG science and technology on reliability and environmental engineering laboratory Beihang UniversityBeijing 100083China

Fault tolerance designs are essential techniques for systems that require high levels of reliability,such as aircraft or spacecraft control *** Fault Coverage(IFC)may lead to the failure of a system or subsystem even with adequate *** studies of IFC mostly concentrated on evaluating Coverage Factor(CF),whereas the system failure behaviors with IFC have rarely been *** that occur in low-layer may be covered by ***,if the coverage is imperfect,uncovered failure will have functional and physical impact on the system *** this thesis,the failure behavior and reliability of IFC of multi-layer systems are studied and a Binary Decision Diagram(BDD)-based modeling and simulation method are proposed to evaluate system *** a case,the failure behavior of an aero engine electronic controller with IFC is *** results show that the IFC may impact system behavior without taking the IFC into account,the system maintenance intervals may reduce,and thus the maintenance costs will increase.

关键词： Acceleration Binary Decision Diagram(BDD) Failure mechanism Imperfect Fault Coverage Multi-layer system reliability evaluation

Bayesian method for system reliability assessment of overlapping pass/fail data

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Journal of Systems engineering and Electronics 2015年第1期26卷 208-214页

作者： Zhipeng Hao Shengkui Zeng Jianbin Guo School of reliability and Systems engineering Beihang University science and technology on reliability and environmental engineering laboratory

For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve the precision of the system reliability assessment. If the multi-level pass/fail data are overlapping,one challenging problem for the Bayesian analysis is to develop a likelihood function. Since the computation burden of the existing methods makes them infeasible for multi-component systems, this paper proposes an improved Bayesian approach for the system reliability assessment in light of overlapping data. This approach includes three steps： fristly searching for feasible paths based on the binary decision diagram, then screening feasible points based on space partition and constraint decomposition, and finally simplifying the likelihood function. An example of a satellite rolling control system demonstrates the feasibility and the efficiency of the proposed approach.

关键词： system reliability assessment Bayesian analysis limited samples overlapping pass/fail data

Location and allocation problem for spare parts depots on integrated logistics support

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Journal of Systems engineering and Electronics 2019年第6期30卷 1252-1259页

作者： WEN Meilin LU Bohan LI Shuyu KANG Rui School of reliability and Systems engineering Beihang UniversityBeijing 100191China science and technology on reliability and environmental engineering laboratory Beijing 100191China

In equipment integrated logistics support(ILS), the supply capability of spare parts is a significant factor. There are lots of depots in the traditional support system, which makes too many redundant spare parts and causes high cost of support. Meanwhile,the inconsistency among depots makes it difficult to manage spare parts. With the development of information technology and transportation, the supply network has become more efficient. In order to further improve the efficiency of supply-support work and the availability of the equipment system, building a system of one centralized depot with multiple depots becomes an appropriate *** this case, location selection of the depots including centralized depots and multiple depots becomes a top priority in the support system. This paper will focus on the location selection problem of centralized depots considering ILS factors. Unlike the common location selection problem, depots in ILS require a higher service level. Therefore, it becomes desperately necessary to take the high requirement of the mission into account while determining location of depots. Based on this, we raise an optimal depot location model. First, the expected transportation cost is ***, factors in ILS such as response time, availability and fill rate are analyzed for evaluating positions of open depots. Then, an optimization model of depot location is developed with the minimum expected cost of transportation as objective and ILS factors as constraints. Finally, a numerical case is studied to prove the validity of the model by using the genetic algorithm. Results show that depot location obtained by this model can guarantee the effectiveness and capability of ILS well.

关键词： location problem spare parts depot integrated logis tics support genetic algorithm.

An IPC-based Prolog design pattern for integrating backward chaining inference into applications or embedded systems

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Chinese Journal of Aeronautics 2014年第6期27卷 1571-1577页

作者： Li Guoqi Shao Yuanxun Hong Sheng Liu Bin science and technology on reliability and Environment engineering laboratory School of Reliability and Systems Engineering Beihang University

Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, such as data acquisition and task scheduling, which are also crucial. To make the best use of the advantages and bypass the disadvantages, it is attractive to integrate Prolog with programs developed by other languages. In this paper, an IPC-based method is used to integrate backward chaining inference implemented by Prolog into applications or embedded systems. A Prolog design pattern is derived from the method for reuse, whose principle and definition are provided in detail. Additionally, the design pattern is applied to a target system, which is free software, to verify its feasibility. The detailed implementation of the application is given to clarify the design pattern. The design pattern can be further applied to wide range applications and embedded systems and the method described in this paper can also be adopted for other logic programming languages.

关键词： Backward chaining inference Design method Embedded systems Inference engines Inter-process communication Prolog