A modified method to calculate reliability index using maximum entropy principle

Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method.

THE RANDOM VARIATIONAL PRINCIPLE IN FINITE DEFORMATION OF ELASTICITY AND FINITE ELEMENT METHOD

In the present paper, we hare mtroduced the random materials. loads. geometricalshapes, force and displacement boundary condition directly. into the functionalvariational formula, by. use of a small parameter perturbation method, a unifiedrandom variational principle in finite defomation of elastieity and nonlinear randomfinite element method are esiablished, and used.for reliability, analysis of structures.Numerical examples showed that the methods have the advontages of simple andconvenient program implementation and are effective for the probabilistic problems inmechanics.

The Principle of Square Hole Machining and It＇s Tooling Structure Design

In order to meet the rapid needs of processing square hole in mechanical equipment, the paper expounds the square hole processing method： planetary wheel method, and analyze the principle of tooling structure and process with computer graphics parameters design. The results that, as long as the appropriate parameters, using the above method not only can punch the square hole, can also be processed triangle, the five angle and hexagonal regular polygon holes. The square hole processing method can provide theoretical basis and engineering reliable reference for related engineering and technical personnel.

可靠性的科学探索:从经典到量子

作为设备稳定服役能力的一种衡量,可靠性对工程技术发展和创新十分重要。基于物理、信息论和统计方法的耦合,可靠性研究正逐步发展并有望成为一门新的科学。同时随着量子技术的发展,量子相干器件及设备将会被大量地植入到传统装备系统中。这不仅给可靠性自身的研究带来新的机遇和挑战,也会使量子物理和可靠性研究交叉起来,导致交叉领域思想上的原始创新。文章首先介绍可靠性研究从工程向科学迈进的历程,然后从可靠性工程需求的视角介绍量子可靠性的基本概念和逻辑,强调量子自洽历史对寿命统计的内在描述,最后结合目前量子技术所面临的退相干挑战,展望可靠性工程对量子技术的潜在应用。

Reliability analysis of retaining walls with multiple failure modes

In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of anti-slipping and anti-overturning based on the upper-bound theory of limit analysis were established, and two kinds of failure modes were regarded as a series of systems with multiple correlated failure modes. Then, statistical characteristics of parameters of the retaining wall structure were inferred by maximal entropy principle. At last, the structural reliabilities of single failure mode and multiple failure modes were calculated by Monte Carlo method in MATLAB and the results were compared and analyzed on the sensitivity. It indicates that this method, with a high precision, is not only easy to program and quick in calculation, but also without the limit of nonlinear functions and non-normal random variables. And the results calculated by this method which applies both the limit analysis theory, maximal entropy principle and Monte Carlo method into analyzing the reliability of the retaining wall structures is more scientific, accurate and reliable, in comparison with those calculated by traditional method.

Optimal bounded control for maximizing reliability of Duhem hysteretic systems

The optimal bounded control of stochastic-excited systems with Duhem hysteretic components for maximizing system reliability is investigated. The Duhem hysteretic force is transformed to energy-depending damping and stiffness by the energy dissipation balance technique. The controlled system is transformed to the equivalent non- hysteretic system. Stochastic averaging is then implemented to obtain the It5 stochastic equation associated with the total energy of the vibrating system, appropriate for eval- uating system responses. Dynamical programming equations for maximizing system re- liability are formulated by the dynamical programming principle. The optimal bounded control is derived from the maximization condition in the dynamical programming equation. Finally, the conditional reliability function and mean time of first-passage failure of the optimal Duhem systems are numerically solved from the Kolmogorov equations. The proposed procedure is illustrated with a representative example.

Maintenance Management Research of a Large-span Continuous Rigid Frame Bridge Based on Reliability Assessment by Using Strain Monitored Data

When the bridge components needing maintenance are the world problem at present,and the health monitoring system is considered to be a very help­ful tool for solving this problem.In this paper,a large number of strain data acquired from the structural health monitoring system(SHMS)installed on a continuous rigid frame bridge are adopted to do reliability assessment.Firstly,a calculation method of punctiform time-dependent reliability is proposed based on the basic reliability theory,and introduced how to cal­culate reliability of the bridge by using the stress data transformed from the strain data.Secondly,combined with“Three Sigma”principle and the basic pressure safety reserve requirement,the critical load effects distribu­tion function of the bridge is defined,and then the maintenance reliability threshold for controlling the unfavorable load state which appears in the early operation stage of this type bridge is suggested,and then the combi­nation of bridge maintenance management and health monitoring system is realized.Finally,the transformed stress distribution certifies that the load effects of concrete bridges practically have a normal distribution;as for the concrete continuous rigid frame bridge with C50 strength grade concrete,the retrofit reliability threshold should be valued at 6.13.The methodology suggested in this article can help bridge engineers do effective maintenance of bridges,which can effectively extend the service life of the bridge and bring better economic and social benefits.

船舶结构设计准则和衡准的研究进展

围绕船舶与海上设施设计准则和衡准,聚焦IACS、IMO、ISO/TC8五年来的最新研究进展,考虑了IACS各成员国的新规范、指南,以及地区海事结构安全规则的研发,讨论了数值孪生、营运数据、可靠性和风险评估、设计阶段中人为因素等对结构设计准则发展的影响等热点问题,给出了未来海事规则制定的总体方向的考虑。

任意概率不确定情形下的电动汽车悬置系统固有特性分析

针对电动汽车动力总成悬置系统(Powertrain Mounting System,PMS)参数可能被处理为不同类型概率变量的情形,提出了一种基于任意多项式混沌(Arbitrary Polynomial Chaos,APC)展开和最大熵原理(Maximum Entropy Principle,MEP)的电动汽车PMS固有特性不确定性分析方法。采用概率模型描述任意概率不确定情形下的PMS参数,通过APC展开获得任意概率不确定情形下PMS固有特性不确定性响应的前几阶统计矩,通过MEP拟合不确定性响应的概率密度函数(Probability Density Function,PDF)和累积分布函数(Cumulative Distribution Function,CDF)等信息,通过算例分析了5种概率不确定情形下的电动汽车PMS固有特性响应。分析结果表明,以蒙特卡洛法作为参考,所提出的方法可有效地分析不同概率不确定情形下的PMS固有特性响应,分析具有较高的计算精度和计算效率,能进一步获得响应满足设计要求的可靠度。

水轮机顶盖排水泵动态剩余寿命综合预测方法

为保障水电厂机组安全平稳运行,优化检修策略,针对水轮机顶盖排水系统,提出了一种顶盖排水泵剩余寿命预测算法,在基于实时数据的基础上,结合可靠性原理,根据顶盖排水泵的振动速度、振动位移、抽水流量、抽水时间分别计算出其对应运行可靠度,融合得到顶盖排水泵综合运行可靠度,结合极限学习机算法构建剩余寿命评估模型,实现了水轮机顶盖排水泵动态剩余寿命综合预测,结合水电厂顶盖排水系统实时数据,验证了该方法的有效性和可行性。

人工智能治理原则的实践导向:可靠性、问责制与社会协同

人工智能的迅速发展与应用带来了难以避免的治理缺口。为了寻求敏捷治理,全球范围内陆续出台了一批具有"软法"性质的治理原则。通过对88份原则文本的整合与分析,聚焦其中的实践准则,研究发现在激增的文本和多元化的主张下,存在着一个公共的问题域:人工智能系统应该满足怎样的技术特性?应该如何应对技术的社会后果?应该以怎样的社会组织形式开展治理实践?尽管围绕这些问题不同原则的主张之间仍然存在张力,但不可否认,当下人工智能治理领域已经形成了一个具备共识基础的行动框架。基于文本分析,众多原则条目可以归纳为三项实践准则:可靠性原则、问责制原则和社会协同原则,它们分别回应了上述问题。其中,可靠性原则和问责制原则设定了构建符合期望的技术系统、应对技术的社会后果这两组相互补充的治理目标,而社会协同原则探讨了怎样的社会行动结构能够支持和保障这些目标的实现,三者构成了人工智能治理的行动框架。

某新型液压电磁阀的可靠性分析策略

针对某新型液压电磁阀可靠性试验缺乏指导原则的问题,对传统故障模式影响及危害性分析(Failure Mode Effects and Criticality Analysis,FMECA)方法进行了改进,并基于改进后的FMECA分析方法对该阀进行可靠性理论分析。将模糊综合评判方法引入传统FMECA分析方法中,通过建立因素集、评价集和权重集确定评估框架,再引入“梯形模糊数”提高FMECA分析方法的准确性,应用改进后的分析方法计算得到该电磁阀薄弱环节的影响因素。将影响因素进一步划分并通过二次分析确定了影响因素中的最极限工况。最后,通过仿真验证了可靠性理论分析方法的正确性,为该阀提供可靠性研究及试验的参考标准。

Principle of maximum entropy for reliability analysis in the design of machine components

We studied the reliability of machine components with parameters that follow an arbitrary statistical distribution using the principle of maximum entropy(PME).We used PME to select the statistical distribution that best fits the available information.We also established a probability density function(PDF)and a failure probability model for the parameters of mechanical components using the concept of entropy and the PME.We obtained the first four moments of the state function for reliability analysis and design.Furthermore,we attained an estimate of the PDF with the fewest human bias factors using the PME.This function was used to calculate the reliability of the machine components,including a connecting rod,a vehicle half-shaft,a front axle,a rear axle housing,and a leaf spring,which have parameters that typically follow a non-normal distribution.Simulations were conducted for comparison.This study provides a design methodology for the reliability of mechanical components for practical engineering projects.

电厂运行控制系统设计可靠性原则的研究

电厂运行控制系统执行核电厂主要监控任务,在设计阶段就要考虑可靠性。制定并贯彻可靠性原则是设计人员开展可靠性设计的途径。目前,电厂运行控制系统设计的可靠性原则缺乏系统的规划和考虑。为解决这个问题,首先研究了军工行业上层的可靠性原则,将其与核电设计现状作对比,归纳出适合电厂运行控制系统的原则,并形成通用的可靠性原则。通用的可靠性原则包括简化设计、余度设计、容错设计、环境防护设计等。然后,通过研究以往核电项目仪控系统的工程设计经验,形成适用于电厂运行控制系统的具体可靠性原则。具体可靠性原则包括结构设计、功能分配、信号失效管理、系统故障诊断等。将这些可靠性原则贯彻于电厂运行控制系统的工程设计中,可以降低系统失效概率,得到满足可靠性要求的综合最优设计。

基于开关原理国民体质测试器材可靠性检测的设备研究

为解决我国基于开关原理国民体质测试器材可靠性检测设备现有技术中存在的不足,本文阐述了一款通过直流电机和曲柄连杆结构相结合,该设备的设计原理是利用直流电机的旋转带动曲柄连杆,实现对试样的循环加载,以此检测开关原理国民体质测试器材的可靠性,实现了对该类检测设备通用性、科学性、精密性的预期效果。

通信车供电系统可靠性设计

通信车供电系统是通信车辆在正常和极端环境下安全有效运行、成功完成各种通联任务、保证车辆生命力的关键。如何对通信车供电系统进行合理有效的可靠性设计,使通信车在稳定实现各项任务通联功能的同时,又能保证车辆供电系统的稳定性和可靠性,成为车辆供电系统设计中的重要环节和技术难点。论文基于通信车供电系统的组成及工作原理,建立了供电系统及其各单元的可靠性模型,采用专家评分法对可靠性指标进行了合理分配,使供电系统各单元的平均故障间隔时间更符合供电系统可靠性的实际要求。同时根据供电系统的可靠性模型,进行了故障模式影响分析,识别了供电系统的薄弱环节,并进行了相应的可靠性设计(包括工艺设计、元器件质量控制、裕度设计和耐环境设计),以减少通信车供电系统的故障发生率,消除系统的潜在故障隐患,提高了通信车供电系统的可靠性水平。

基于状态信息的航空发动机运行可靠性评估

航空发动机是飞机的'心脏',其运行可靠性评估对保障飞行安全具有重要意义。受不同运行状况的影响,航空发动机退化程度和失效时间具有较大的离散性。针对单台航空发动机运行可靠性评估难以运用基于大样本统计的传统可靠性方法的问题,提出基于状态信息的航空发动机运行可靠性评估方法。该方法利用核主成分分析建立状态子空间,描述航空发动机状态性能的变化;计算正常状态与当前状态子空间基矢量的主夹角,利用映射函数将主夹角转化为运行可靠度。采用美国国家航空航天局提供的航空发动机全寿命仿真数据和某维修厂现场实测数据对所提出的方法进行验证,结果表明该方法能够合理地评估单台航空发动机的运行可靠性,为小样本条件下航空发动机运行可靠性评估提供有效手段。

熵原理及其在电力系统可靠性中的应用

本文详细阐述了熵最大原理及其与电力系统的密切关系 ,并根据熵最大原理和概率论的有关知识 ,构造了条件约下的增广熵函数。基于此 ,推导出一系列电力系统可靠性指标的计算公式。总结并指出熵原理在电力系统可靠性分析、预测、评估。

基于最大熵原理的基桩竖向承载力的可靠度分析

基于无量纲计算模式,研究了极限状态方程中每个随机变量对基桩竖向承载力可靠度分析的影响,并采用最大熵原理将可靠度指标的计算转化为熵密度函数的计算。计算熵密度函数时采用牛顿迭代法,从而解决了在分析基桩竖向承载力的可靠度时可能产生的迭代不收敛的情况。在计算中,采用的数据直接来源于样本,减少了对已有数据和经典概率分布的依赖。利用无量纲计算模式推导了基桩竖向承载力的失效概率的计算公式。工程实例分析表明,其计算效率较高且精度满足工程需要。