岩石边坡稳定性的可靠性理论评价研究

本文撇开了传统的整体刚性极限平衡法和条分法等安全每当法评价边坡的稳定性，采用可靠性理论对边坡稳定性进行评价，实践证明它是一种更符合工程实际的新方法。     

空调器印剧电路板(PCB)无铅焊点寿命评估研究

由于无铅焊料的应用,无铅焊点的可靠性问题得到了关注.本文针对无铅焊点的空调器印刷电路板(PCB),结合实际使用条件,采用加速寿命的方式,测试了焊点的寿命.并针对温度循环条件下的焊点,使用有限元模拟技术计算测定了其寿命,并与实验的结果进行了比较,取得了较吻合的结果.     

基于贝叶斯网络的人因可靠性评价

提出一种贝叶斯网络的人因可靠性评价(HRABN)方法,其中的每个因子对应于贝叶斯网络中的节点,该方法可对人因可靠性作定量分析和定性分析。在定性分析上,节点的因果关系(HRA中的因子关系)及需要改进的薄弱节点都直观地显示在层次图中;在定量分析方面,对节点因子后验概率的推断通过HRA中的先验信息(包含仿真数据、现场操作及专家知识等)和最新信息得到。如果人因可靠性贝叶斯网络中的每个节点的先验概率分布和后验概率分布都已知,模型的可信性就可通过贝叶斯因子进行定量验证。贝叶斯网络扩展性好,当有新的节点因子需要考虑时,只需要补充对应的节点;笔者的方法也能很好地应用在不同行业的HRA。     

利用遗传算法进行软件可靠性增长模型参数估计

为解决利用传统数值方法估计软件可靠性增长模型参数值时存在的问题 ,笔者讨论了利用遗传算法进行求解的相关策略 ;提出了一种新的编码方式及变异算子 ;通过涉及多个模型的实验 ;采用实际数据 ,对所提出算法的效果与传统数值方法进行了对比。实验与对比分析结果显示 :该算法针对这些模型表现出了良好的普适性。     

提高冷拔内模使用可靠性的研究

用安全学科的观点 ,对冷拔内模进行宏观痕迹分析和磨损失效模式的确定 ,并结合摩擦学精典的磨损理论 ,对冷拔内模进行微观磨损机理分析 ,从而为提高冷拔内模使用可靠性提供了理论依据和有效措施。     

生态足迹模型在村庄层面应用的探索

以广西铜匠村的生态足迹模型为例探讨了生态足迹法在村庄层面应用的适用性。结论表明,生态足迹模型在衡量村庄生态状况时有着更为可靠的准确性,但也存在4种因素限制其精确性,数据获取较难、外出务工者较多、生态效益较大以及土地"兼职"较广。针对外出务工者的影响,提出了其时间折算法,对于其他缺陷则阐明了在模型完善方面的研究现状。     

Using data mining technology to explore causes of inaccurate reliability data and suggestions for maintenance management

Reliability data reflects equipment safety and provides a reference for setting inspection period, thereby serving as crucial information for the implementation of equipment integrity management policies. The calculation foundation of reliability data is maintenance records of adequate data quality. However, maintenance records of doubtful quality are common. Despite excluding poor quality recodes and using only the remaining maintenance recodes to calculate the reliability data, the calculated results generally lack a sufficient degree of confidence. This study applied data mining technology, including quality metrics, the association rule, and clustering, to explore the cause of low-quality maintenance data. The results revealed that the low data quality of maintenance records was due to ineffective maintenance policies, the low integrity of key system columns, nonadherence to the policy, and misunderstanding of column definitions. The proposed method successfully identified the causes of low-quality maintenance records. By incorporating the method into the function module of a CMMS, operators can equip the system with self-diagnosis, self-supervision, and continuous optimization functions.     

System failure probability evaluation using fault tree analysis and expert opinions in intuitionistic fuzzy environment

In quantitative fault tree analysis of a system, exact failure probability values of components are utilized to calculate the failure probability of the system. However, in many real world problems, it is problematic to get precise and sufficient failure data of system components due to insufficient or imprecise information about components, changing environment or new components. A methodology has already been developed by employing fuzzy set theory for the system reliability evaluation by utilizing qualitative failure data of system components when quantitative failure data of components are inaccessible or insufficient. This paper extends the concept of fuzzy set to intuitionistic fuzzy set and proposes a novel approach to evaluate system failure probability using intuitionistic fuzzy fault tree analysis with qualitative failure data of system components. The qualitative failure data such as expert opinions are collected as linguistic terms. These linguistic terms are then quantified by triangular intuitionistic fuzzy numbers in form of membership function and non-membership function. Additionally, a method is developed for combining the different opinions of experts. To illustrate the applicability of proposed approach, a case study of the crude oil tank fire and explosion accident is performed. The obtained results are very close to the results from pre-existing approaches which confirm that the proposed approach is a more realistic alternative for the study of system reliability in intuitionistic fuzzy environment when quantitative failure data of system components are not known. To help decision makers for improving the security execution of the crude oil tank system, importance measures including Fussell-Vesely importance and cut sets importance are also executed.     

Reliability evaluation of fire alarm systems using dynamic Bayesian networks and fuzzy fault tree analysis

In almost all industries, fire alarm systems play a vital role in the reducing the risks associated with fires and damages. Therefore, it is necessary to evaluate their reliability and performance in emergency situations. The present study aimed to use fault tree analysis (FTA) to determine the root causes involved in the failure of fire alarm systems, to use Fuzzy set theory and expert elicitation to determine relative probabilities, and finally, to evaluate the reliability of a fire alarm system using dynamic Bayesian networks (BNs) during a thirty-six months period. A total of 29 basic events were detected from the FT. The reliability of the fire alarm system was estimated at 0.954 according to the FT and 0.957 according to conventional BNs. The reliability of the fire alarm system after 36 months was estimated at 0.375 according to dynamic BNs. All the events involved in the failure of fire alarm systems were drawn in the fault tree diagram. The results indicate that remodeling of these systems and simultaneous construction activities are the most important factors in the failure of the fire alarm system. System reliability can also be increased to 0.965 by providing preventive and control measures to reduce the probability of critical events.     

Component joint importance measures for maintenances in submarine blowout preventer system

In order to improve the performance and maintain the interconnection components of the subsea pipeline ram blowout preventer system, the idea of importance analysis can be used to solve this problem. This paper uses an extended joint integrated importance measure to effectively analyze the characteristics of component failures of the blowout preventer system. The interaction between two components is considered to improve system performance while the failed component is being repaired. In order to facilitate subsequent maintenance and repair work, the effects of changes in different parameters on the importance value are considered. Finally, the analysis of a numerical example of the submarine pipeline ram blowout preventer system is carried out to verify the proposed method.