Optimal Design of Multiple Stress Constant Accelerated Life Test Plan on Non-rectangle Test Region

For optimal design of constant stress accelerated life test（CSALT） with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.

Optimal Design of Multiple Stresses Accelerated Life Test Plan Based on Transforming the Multiple Stresses to Single Stress

For planning optimum multiple stresses accelerated life test plans, a commonly followed guiding principle is that all parameters of the life-stress relationship should be estimated, and the number of the stress level combinations must be no less than the number of parameters of the life-stress relationship. However, the general objective of an accelerated life test（ALT） is to assess thep-th quantile of the product life distribution under normal stress. For this objective,estimating all model parameters is not necessary, and this will increase the cost of test. Based on the theoretical conclusion that the stress level combinations of the optimum multiple stresses ALT plan locate on a straight line through the origin of coordinate, it is proposed that a design idea of planning the optimum multiple stresses ALT plan through transforming the problem of designing an optimum multiple stresses ALT plan to designing an optimum single stress ALT plan. Moreover, a method of planning the optimum multiple stresses ALT plan which can avoid estimating all model parameters is established. An example shows that, the proposed plan which only has two stress level combinations could achieve an accuracy no less than the traditional plan, and save the test time and cost on one stress level combination at least; when the actual product life is less than the design value, even the deviation of the model initial parameters value is up to 20%, the variance of the estimation of thep-th quantile of the proposed plan is still smaller than the traditional plans approximately 25%. A design method is provided for planning the optimum multiple stresses ALT which uses the statistical optimum degenerate test plan as the optimum multiple stresses accelerated life test plan.

Design of Accelerated Life Test Plans——Overview and Prospect

Accelerated life test(ALT) is currently the main method of assessing product reliability rapidly, and the design of efficient test plans is a critical step to ensure that ALTs can assess the product reliability accurately, quickly, and economically. With the promotion of the national strategy of civil-military integration, ALT will be widely used in the research and development(R&D) of various types of products, and the ALT plan design theory will face further challenges. To aid engineers in selecting appropriate theories and to stimulate researchers to develop the theories required in engineering, with focus on the demands for theory research that arise from the implementation of ALT, this paper reviews and summarizes the development of ALT plan design theory. The development of the theory and method for planning optimal ALT for location-scale distribution, which is the most applied and mature theory of designing the optimal ALT plan, are described in detail. Taking this as the center of radiation, some problems that ALT now faces, such as the verification of the statistical model, limitation of sample size, solutions of resource limits, optimization of the test arrangement, and management of product complexity, are discussed, and the general ideas and methods of solving these problems are analyzed. Suggestions for selecting appropriate ALT plan design theories are proposed, and the urgent solved theory problems and opinions of their solutions are proposed. Based on the principle of convenience for engineers to select appropriate methods according to the problems found in practice, this paper reviews the development of optimal ALT plan design theory by taking the engineering problems arising from the ALT implementation as the main thread, provides guidelines on selecting appropriate theories for engineers, and proposes opinions about the urgent solved theory problems for researchers.

A Planning Method for Operational Test of UAV Swarm Based on Mission Reliability

The unmanned aerial vehicle(UAV)swarm plays an increasingly important role in the modern battlefield,and the UAV swarm operational test is a vital means to validate the combat effectiveness of the UAV swarm.Due to the high cost and long duration of operational tests,it is essential to plan the test in advance.To solve the problem of planning UAV swarm operational test,this study considers the multi-stage feature of a UAV swarm mission,composed of launch,flight and combat stages,and proposes a method to find test plans that can maximize mission reliability.Therefore,a multi-stage mission reliability model for a UAV swarm is proposed to ensure successful implementation of the mission.A multi-objective integer optimization method that considers both mission reliability and cost is then formulated to obtain the optimal test plans.This study first constructs a mission reliability model for the UAV swarm in the combat stage.Then,the launch stage and flight stage are integrated to develop a complete PMS(Phased Mission Systems)reliability model.Finally,the Binary Decision Diagrams(BDD)and Multi Objective Quantum Particle Swarm Optimization(MOQPSO)methods are proposed to solve the model.The optimal plans considering both reliability and cost are obtained.The proposed model supports the planning of UAV swarm operational tests and represents a meaningful exploration of UAV swarm test planning.

Optimum design of equivalent accelerated life testing plans based on proportional hazards-proportional odds model

The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented. The defined equivalent test plan is the test plan that has the same value of the determinant of Fisher information matrix. The equivalent test plan of step stress accelerated life testing （SSALT） to a baseline optimum constant stress accelerated life testing （CSALT） plan is obtained by adjusting the censoring time of SSALT and solving the optimization problem for each case to achieve the same value of the determinant of Fisher information matrix as in the baseline optimum CSALT plan. Numer- ical examples are given finally which demonstrate the equivalent SSALT plan to the baseline optimum CSALT plan reduces almost half of the test time while achieving approximately the same estimation errors of model parameters.

Planning failure-censored constant-stress partially accelerated life test

This article deals with the case of the failure-censored constant-stress partially accelerated life test （CSPALT） for highly reliable materials or products assuming the Pareto distribution of the second kind. The maximum likelihood （ML） method is used to estimate the parameters of the CSPALT model. The performance of ML estimators is investigated via their mean square error. Also, the average confidence interval length （IL） and the associated co- verage probability （CP） are obtained. Moreover, optimum CSPALT plans that determine the optimal proportion of the test units al- located to each stress are developed. Such optimum test plans minimize the generalized asymptotic variance （GAV） of the ML estimators of the model parameters. For illustration, Monte Carlo simulation studies are given and a real life example is provided.

Step-stress accelerated degradation test planning based on Wiener processwith correlation

To assess the lifetime distribution of highly reliable or expensive product,one of the most commonly used strategies is to construct step-stress accelerated degradation test(SSADT)which can curtail the test duration and reduce the test cost.In reality,it is not unusual for a unit with a higher degradation rate which exhibits a more volatile degradation path.Recently,Ye,Chen,and Shen[(2015).A new class of Wiener process models for degradation analysis.Reliability Engineering and System Safety,139,58–67]proposed a Wiener process to capture the positive correlation between the drift rate and the volatility.In this paper,an optimal SSADT plan is developed under the assumption that the underlying degradation path follows the Wiener process with correlation.Firstly,the stochastic diffusion process is introduced to model a typical SSADT problem.Then the design variables,including the sample size,the measurement frequency and the numbers of measurements under each stress level,are optimised by minimising the asymptotic variance of the estimated p-percentile of the product’s lifetime distribution subject to the total experimental cost not exceeding a pre-specified budget.Finally,a numerical example is presented to illustrate the proposed method.

钠冷快堆组件编码自动识别装置的试验研究及应用

为保证钠冷快堆入堆组件的正确性,本文设计将组件编号转换为二维码并标记在组件上,在新组件转运设备上安装读码设备,通过读码设备对入堆新组件编码进行自动识别,将组件编码转换为组件编号并通过通讯传递至燃料操作监控系统。监控系统将其与换料计划中的组件编号进行比较,可判断转运的入堆新组件是否正确,提高组件操作的可靠性和安全性。为确定组件编码的各项技术参数,通过枚举法分析并总结了影响组件编码识别的各种因素,确定出单一因素试验方案,最终通过各种参数与功能试验,获得了适用于大型快堆电站组件编码自动识别装置的组件编码各项参数,试验结果证明研发目标完全实现。

融合改进哈里斯鹰和改进动态窗口的机器人动态路径规划

针对动态环境的移动机器人路径规划问题,提出了一种改进哈里斯鹰算法(IHHO)与改进动态窗口算法(IDWA)的融合算法(IHHO-IDWA)。首先,针对哈里斯鹰算法后期搜索性能不足等问题,提出了融合自适应混沌和核心种群动态划分策略、融合黄金正弦策略以及动态云最优解扰动策略来提高算法的性能。其次,针对动态窗口算法存在规划的路径长和易陷入死锁等问题,提出了三个改进策略:增加子函数,保证算法能够规划出更短的路径;提出自适应权重策略,平衡算法局部避障能力和全局搜索性能;设定初始航向角,避免路径冗余。最后,通过测试函数、CEC2014函数的数值实验和静态、动态路径规划实验,验证了IHHO和IDWA性能有明显提升;通过50×50大型动态地图验证了融合算法较对照组算法规划的路径缩短了11.51%,证明了该方法的优越性。

Novel Accelerating Life Test Method and Its Application by Combining Constan Stress and Progressive Stress

Constant stress accelerated life tests(ALTs) can be applied to obtain a high estimation accuracy of reliability measure?ments, but these are time?consuming tests. Progressive stress ALTs can yield failures more quickly but cannot guaran tee the estimation accuracy of reliability measurements. In this paper, a progressive?constant combination stress ALT is proposed to combine the merits of both tests. The optimal plan, in which the design variables are the initial pro?gressive stress level, the progressive stress ramp rate, the sample allocation proportion of the progressive stress and the constant stress level, is determined using the principle of minimizing the asymptotic variance of the maximum likelihood estimator of the natural log reliable life for the connectors. A comparison between the optimal PCCSALT plan and the CSALT plan with the same sample size and estimation accuracy shows that the test time is reduced by 13.59% by applying the PCCSALT.

Inference and optimal design on step-stress partially accelerated life test for hybrid system with masked data

Under Type-Ⅱ progressively hybrid censoring, this paper discusses statistical inference and optimal design on stepstress partially accelerated life test for hybrid system in presence of masked data. It is assumed that the lifetime of the component in hybrid systems follows independent and identical modified Weibull distributions. The maximum likelihood estimations(MLEs)of the unknown parameters, acceleration factor and reliability indexes are derived by using the Newton-Raphson algorithm. The asymptotic variance-covariance matrix and the approximate confidence intervals are obtained based on normal approximation to the asymptotic distribution of MLEs of model parameters. Moreover,two bootstrap confidence intervals are constructed by using the parametric bootstrap method. The optimal time of changing stress levels is determined under D-optimality and A-optimality criteria.Finally, the Monte Carlo simulation study is carried out to illustrate the proposed procedures.

无人机检测桥梁多目标点路径规划方法研究

针对无人机检测桥梁下部结构多目标点路径规划问题,建立无人机检测桥梁墩柱的数字模型.利用改进后的Henon混沌映射对传统人工蜂群算法(ABC算法)中的蜜源初始化阶段和侦察蜂搜索阶段进行优化,提出了一种基于混沌映射改进后的ABC算法(HABC算法),通过仿真对比分析发现HABC算法相较于ABC算法迭代收敛更快,平均评价函数值也优于ABC算法,实现全局路径规划问题中算法的优化.将HABC算法和贪心策略相结合提出一种贪心HABC算法,实现UAV检测桥梁墩柱结构多目标点路径规划,通过仿真验证了算法的可靠性.结果显示通过牺牲少量路径总长度可有效节省算法运行时间.

基于混沌算子增强遗传算法的资源统筹模型

面向复杂试验任务和多样性试验资源统筹调配需求,针对资源配置不均、效率低下等问题,基于试验资源统筹的业务流程,研究提出了一种基于混沌遗传算法的试验资源统筹方法。利用遗传算法建立试验资源统筹调配过程的数学模型,基于Logistic混沌映射构造混沌交叉算子和变异算子,并结合具体试验案例进行了算法设计实现和验证。算法避免了过早收敛、陷入局部最优等缺陷,能够快速实现试验资源优化配置,对于提高试验资源统筹利用的科学性具有积极作用。

融合模式搜索的蝗虫优化算法及其应用

在智能优化算法应用于复杂优化问题的求解过程中,平衡开发和探索以获得最优解具有重要意义。因此针对传统蝗虫优化算法在处理一些较为复杂的优化问题时出现的收敛精度低、搜索能力弱且容易陷入局部最优等缺陷,提出一种融合模式搜索的蝗虫优化算法。首先引入Sine混沌映射初始化蝗虫个体种群位置,减少个体重叠概率以增强种群迭代初期的多样性;其次利用模式搜索法,对种群目前找到的最优目标展开局部搜索,提高算法的收敛速度与寻优精度;同时为了避免算法后期陷入局部最优,引入了基于凸透镜成像的反向学习策略。实验部分通过对改进的蝗虫算法进行消融实验,验证了Sine混沌映射、模式搜索、反向学习每个策略的独立有效性。并用两组测试函数进行仿真实验,采用Wilcoxon秩和检验、Friedman检验的方法进行结果分析。实验结果均表明了融合模式搜索法改进的蝗虫算法在收敛速度与寻优精度上得到明显提高。最后,将其应用于移动机器人路径规划,测试结果进一步验证了改进算法的有效性。

建设方视角下的建筑工程检测管理

随着城市建设的发展,在建筑建设领域,建设单位委托第三方工程质量检测单位进行项目全过程质量把控参与度越来越深,为此,论文以建设单位视角论述第三方检测单位在建设中的管理重要意义、存在的问题,提出了把控要点及解决方法,为落实建设单位质量、安全首要责任制,提升工程质量,保证安全,进一步健全工程质量责任体系提供建议,同时为各参建方在建设过程中的检测管理提供参考。

城际轨道交通车辆基地总平面布局关键要点研究

针对城际轨道交通车辆基地总平面布置限制因素多、洗车效率不高、高速试车线设置困难等问题,以杭临城际上泉车辆基地设计为例,对城际轨道交通车辆基地总平面布局关键要点进行研究。通过对车辆基地功能定位、用地条件、限制因素、洗车及试车线设置方式等进行分析,提出总平面布置及竖向优化方案、类贯通洗车方案、多种敷设方式组合试车线设置方案,解决用地受限条件下高效洗车及高速试车线设置难题。实际应用表明相关方案可较大程度提升运营效率,为其他类似车辆基地设计提供参考。

高铁列控系统工程仿真测试平台建设方案研究及验证

高速铁路列控系统安全等级高,设备组成繁多,功能结构和接口关系非常复杂,现场测试和验证的难度极大。利用仿真测试技术,能将完全依赖于现场的动态验证测试工作通过仿真测试实施完成,可以进一步提高测试覆盖度、降低对运输的影响。在对项目建设必要性、建设目标、技术方案等进行研究的基础上,对地面设备、车载设备、仿真系统方案等进行具体研究。经比选,高铁列控系统工程仿真测试平台地面设备采用半实物、半仿真结构,利用云平台技术,具有更好的扩展性、经济性;车载设备采用完全真实设备,提高了测试的可信性和真实性。通过构建仿真测试平台并基于湖杭高铁仿真环境进行验证,研究结果表明,与现场测试相比,仿真测试完成了更多的场景、案例以及进路测试,数量分别增加了275%、336%及442%,可以进一步提升列控系统测试的质量、深度和广度。

航空发动机装试网络计划模型及应用研究

本文以项目管理网络计划技术为基础,结合单位实际对航空发动机试验试车任务现状和管理特点进行分析,针对项目管理在资源配置管理、组织职能、保障措施等方面出现的问题,研究建立航空发动机装试网络计划模型,并应用于装配、试验、试车任务的计划管理和冲突协调。

黄河水沙监测数据分析模型

为研究黄河小浪底水库下游某水文站水沙通量的变化规律和“调水调沙”效果,以2016-2022年水位、水流量与含沙量的实际监测数据为依据,估算出年均径流量325亿立方米,年均排沙量2亿吨.分别使用双对数回归分析、M-K检验、小波分析、R/S分析对水沙通量的敏感性、突变性、周期性、趋势性进行了分析,得出结论:水位每增加1%,含沙量就增加37.63%,含沙量关于水位非常敏感;水沙通量均在2018年3月发生了突变;水沙通量均以18月为主周期振荡;水通量、沙通量在未来2年分别是增长趋势和下降趋势.使用傅里叶级数叠加线性函数预测未来2年的水沙通量,并建立了0-1规划模型对今后2年的监测方案进行了优化.通过比较“调水调沙”前后水沙通量、河底高程的变化,证明了“调水调沙”效果非常显著.

多策略融合的改进麻雀搜索算法及其AGV路径规划应用

针对麻雀搜索算法(sparrow search algorithm,SSA)存在依赖初始种群分布,易于陷入局部最优解,以及迭代后期种群多样性减少等问题,提出一种多策略融合的改进麻雀搜索算法(improved sparrow search algorithm,ISSA)。首先,采用Sobol序列初始化种群,保证初始种群的多样性;其次,分别引入随机反向学习策略和螺旋觅食策略改进发现者位置更新公式和加入者位置更新公式,以增强算法的全局搜索能力和跳出局部最优解的能力;最后,引入柯西变异对可能陷入局部最优解的麻雀进行扰动。实验选取9个标准测试函数进行性能测试,实验结果表明,改进后的算法性能有较大提升。将ISSA应用于AGV(automated guided vehicle)路径规划,在3种地图环境下分别可以达到最优值13.1356、28.8345和44.3649,寻优能力和稳定性较原算法有较大提升。