Imprecise reliability assessment for heavy numerical control machine tools against small sample size problem

Small sample size problem is one of the main problems that heavy numerical control (NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliability data such as reliability data of similar products, expert opinion, and engineers’ experience are used in reliability assessment. However, the existing mathematical theories cannot simultaneously process the above reliability data of multiple types, and thus imprecise probability theory is introduced. Imprecise probability theory can simultaneously process multiple reliability data by quantifying multiple uncertainties (stochastic uncertainty, fuzzy uncertainty, epistemic uncertainty, etc.) together. Although imprecise probability theory has so many advantages, the existing natural extension models are complex and the computation result is imprecise. Therefore, they need some improvement for the better application of reliability engineering. This paper proposes an improved imprecise reliability assessment method by introducing empirical probability distributions to natural extension model, and the improved natural extension model is applied to the reliability assessment of heavy NC machine tool spindle to illustrate its effectiveness.     

广义满意度原理及其特性分析

采用系统分析法，定义并分析了广义满意度、满意序、满意标准、满意解等基本概念．通过对广义满意度原理公理化系统的构造，分析了广义满意度原理应用过程中满意解的获取、识别、转化等重要性质，并得出了满意度和满意水平的运算关系。     

系统可靠性的冗余分配及其神经网络优化方法研究

冗余设计是改善系统可靠性的一种有效方法。本文综述了最优冗余分配方法的发展现状，指出了现有方法的不足，提出了一种基于神经网络的最优分配算法。     

工作时间具有模糊性时的可靠性分析方法

本文应用模糊数学的基本概念和方法,将清晰工作时间拓广到模糊工作时间,将普通 事件拓广到模糊事件,将普通可靠性拓广到模糊可靠性,导出了模糊可靠性常用指标 的计算公式,建立了不可修复系统的模糊可靠性数学模型。      

FUZZY METHOD FOR FAILURE CRITICALITY ANALYSIS

IntroductionFailure mode,effect and criticality analysis( FMECA) is a design methodology which putsforward preventive and corrective methods thatmay be taken to improve the reliability of prod-ucts through the analysis of the various potentialfailure modes of the different components of thesystem,their influence on the system and theseverity of their consequences in system design.FMECA is suitable for the study of the influenceof the failure of system components on the sys-tem and can be us…     

Stochastic Fatigue Life and Reliability Prediction Based on Residual Strength

A randomized approach is developed to solve a deterministic equation. The method uses random deterministic approach to achieve the fatigue life based on residual strength and S-N curve. We propose a oneto-one transformation method to deduce the distribution of fatigue life from the residual strength. The proposed method is simple and effective, and can be used for fatigue life prediction. An example is given to illustrate how the method works.     

Reliability Analysis of Filtering Reducers Considering Temperature Correction and Shock Load of Space

Owing to some excellent properties (such as large transmission ratio, high reliability, high precision, large stiffness, small volume and long service life), filtering reducers are suitable for occasions with high requirements (e.g. space equipment). However, the tough working condition in space (including frequent changes of temperature, and large temperature difference combined with shock loads) may significantly affect the reliability. In this paper, the expressions of the minimal and maximal instantaneous transmission ratios (ITRs) considering temperature correction are developed. The minimal and maximal ITRs from simulation are used to verify the accuracy. Moreover, the reliability of a filtering reducer under different temperatures and the shock load are calculated, respectively. The research is beneficial to the design of spacecraft mechanism.     

基于知识的具有关键设备的生产调度问题遗传编码方法与算法

针对具有关键设备的调度问题,提出了基于知识的问题编码方法,包括染色体结构表法、染色体构造算法和操作序列生成算法,并给出了编码实例。