Reliability and sensitivity analyses of HPT blade-tip radial running clearance using multiply response surface model

To reasonably design the blade-tip radial running clearance(BTRRC) of high pressure turbine and improve the performance and reliability of gas turbine, the multi-object multi-discipline reliability sensitivity analysis of BTRRC was accomplished from a probabilistic prospective by considering nonlinear material attributes and dynamic loads. Firstly, multiply response surface model(MRSM) was proposed and the mathematical model of this method was established based on quadratic function. Secondly, the BTRRC was decomposed into three sub-components(turbine disk, blade and casing), and then the single response surface functions(SRSFs) of three structures were built in line with the basic idea of MRSM. Thirdly, the response surface function(MRSM) of BTRRC was reshaped by coordinating SRSFs. From the analysis, it is acquired to probabilistic distribution characteristics of input-output variables, failure probabilities of blade-tip clearance under different static blade-tip clearances δ and major factors impacting BTRRC. Considering the reliability and efficiency of gas turbine, δ=1.87 mm is an optimally acceptable option for rational BTRRC. Through the comparison of three analysis methods(Monte Carlo method, traditional response surface method and MRSM), the results show that MRSM has higher accuracy and higher efficiency in reliability sensitivity analysis of BTRRC. These strengths are likely to become more prominent with the increasing times of simulations. The present study offers an effective and promising approach for reliability sensitivity analysis and optimal design of complex dynamic assembly relationship.

Kriging-based reliability analysis of the long-term stability of a deep driftconstructed in the Callovo-Oxfordian claystone

Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(e.g.galleries/alveoli)within the disposal is assured by the liner,which includes two layers:concrete arch segment and compressible material.The latter exhibits a significant deformation capacity(about 50%)under low stress(<3 MPa).Although the response of these underground structures can be governed by complex thermo-hydro-mechanical coupling,the creep behavior of COx claystone has been considered as the main factor controlling the increase of stress state in the concrete liner and hence the long-term stability of drifts.Therefore,by focusing only on the purely mechanical behavior,this study aims at investigating the uncertainty effect of the COx claystone time-dependent properties on the stability of an alveolus of Cigéo during the exploitation period.To describe the creep behavior of COx claystone,we use Lemaitre’s viscoplastic model with three parameters whose uncertainties are identified from laboratory creep tests.For the reliability analysis,an extension of a well-known Kriging metamodeling technique is proposed to assess the exceedance probability of acceptable stress in the concrete liner of the alveolus.The open-source code Code_Aster is chosen for the direct numerical evaluations of the performance function.The Kriging-based reliability analysis elucidates the effect of the uncertainty of COx claystone on the long-term stability of the concrete liner.Moreover,the role of the compressible material layer between the concrete liner and the host rock is also highlighted.

The Reliability of the 300-Yard Shuttle Run in High School Girls Basketball Players

The 300-yard shuttle run is a field test commonly used to assess anaerobic capacity. There is limited documentation regarding the reliability of the shuttle run for various populations. The purpose of this study was to assess the reliability of the 300-yard shuttle run in High School girls basketball players. Thirty nine High School girls basketball players performed two separate sessions of the 300-yard shuttle run. During each session, the participants completed two trials of the 300-yard shuttle run separated by a 5-minute rest period. The trial 1 and 2 scores were 66.2 - 4.9 and 69.1 - 6.0 seconds, respectively. The interclass and intraclass reliability coefficients were r = 0.84 and ICC = 0.83. The standard error of the measure was SEm = 2.2 seconds with 90% confidence limits Of UL： 2.6, LL： 1.9. The typical error expressed as a coefficient of variation percent was CV% = 3.2 with 90% confidence limits Of UL： 3.7, LL： 2.8. Within the parameters of this study, the 300-yard shuttle run is a sufficiently reliable field test for measuring anaerobic capacity.

新能源汽车高寒环境可靠性行驶试验研究

针对行业内新能源汽车高寒环境可靠性行驶试验方法不完善、不统一的现状,文章开发了新的试验方法,对试验环境、试验车辆、试验工况、驾驶操作、检查与记录等做出了明确的要求,同时提供了故障发现、判断和处理的相关途径或措施。通过选取6辆新能源汽车,在内蒙古自治区牙克石市开展试验测试,进行了故障的统计和分析。从试验结果可知,所开发的试验方法行之有效,能够有效激发车辆故障,同时发现了一些新型故障,需要引起整车企业重视,希望该研究可以给整车企业提供相关试验指导。

企业医院门诊患者满意度调查问卷信效度分析

目的编制企业办医院门诊患者满意度评价问卷,并评价其信度与效度。方法通过访谈法、文献资料分析法形成初始问卷,对广西某企业办医院380名来院就诊的门诊患者进行满意度调查,采用条目分析、探索性因子分析和验证性因子分析等方法,确定最终评价问卷并检验其信效度。结果经过统计分析最终确定问卷条目数为18个,问卷的题目信度为0.438~0.856,组成信度为0.846~0.956,收敛效度为0.668~0.782,各公因子间的相关系数小于其收敛效度的平方根。结论编制的门诊患者满意度评价问卷具有较好的信度和效度。

Distributed Collaborative Response Surface Method for Mechanical Dynamic Assembly Reliability Design

Because of the randomness of many impact factors influencing the dynamic assembly relationship of complex machinery, the reliability analysis of dynamic assembly relationship needs to be accomplished considering the randomness from a probabilistic perspective. To improve the accuracy and efficiency of dynamic assembly relationship reliability analysis, the mechanical dynamic assembly reliability（MDAR） theory and a distributed collaborative response surface method（DCRSM） are proposed. The mathematic model of DCRSM is established based on the quadratic response surface function, and verified by the assembly relationship reliability analysis of aeroengine high pressure turbine（HPT） blade-tip radial running clearance（BTRRC）. Through the comparison of the DCRSM, traditional response surface method（RSM） and Monte Carlo Method（MCM）, the results show that the DCRSM is not able to accomplish the computational task which is impossible for the other methods when the number of simulation is more than 100 000 times, but also the computational precision for the DCRSM is basically consistent with the MCM and improved by 0.40-4.63% to the RSM, furthermore, the computational efficiency of DCRSM is up to about 188 times of the MCM and 55 times of the RSM under 10000 times simulations. The DCRSM is demonstrated to be a feasible and effective approach for markedly improving the computational efficiency and accuracy of MDAR analysis. Thus, the proposed research provides the promising theory and method for the MDAR design and optimization, and opens a novel research direction of probabilistic analysis for developing the high-performance and high-reliability of aeroengine.

Distributed collaborative extremum response surface method for mechanical dynamic assembly reliability analysis

To make the dynamic assembly reliability analysis more effective for complex machinery of multi-object multi-discipline(MOMD),distributed collaborative extremum response surface method(DCERSM)was proposed based on extremum response surface method(ERSM).Firstly,the basic theories of the ERSM and DCERSM were investigated,and the strengths of DCERSM were proved theoretically.Secondly,the mathematical model of the DCERSM was established based upon extremum response surface function(ERSF).Finally,this model was applied to the reliability analysis of blade-tip radial running clearance(BTRRC)of an aeroengine high pressure turbine(HPT)to verify its advantages.The results show that the DCERSM can not only reshape the possibility of the reliability analysis for the complex turbo machinery,but also greatly improve the computational speed,save the computational time and improve the computational efficiency while keeping the accuracy.Thus,the DCERSM is verified to be feasible and effective in the dynamic assembly reliability(DAR)analysis of complex machinery.Moreover,this method offers an useful insight for designing and optimizing the dynamic reliability of complex machinery.

QUICK ASSESSMENT METHODOLOGY FOR RELIABILITY OF SOLDER JOINTS IN BALL GRID ARRAY(BGA)ASSEMBLY——PART Ⅱ:RELIABILITY EXPERIMENT AND NUMERICAL SIMULATION

In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days,but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments,the acceleration factors (AF) were obtained for different reliability testing conditions.Furthermore,by using the creep constitutive relation and fatigue life model developed in part I,a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS.As a result,a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.

Fatigue reliability for LNG carrier

The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.

基于改进长期增量成本法的可靠性电价制定方法

随着电力体制改革的不断推进,按照用户差异化需求制定可靠性电价成为完善电价体系的重要方面。文中综合考虑了系统运行方式和可中断响应因子,提出了基于改进长期增量成本法的配电网可靠性电价制定方法。该方法结合所提出的经济投资策略分析了不同运行方式下单位注入功率对经济投资年限的影响,根据不同运行方式下较小的经济投资年限推导了可靠性成本增量,并根据可靠性成本增量计算出不同可中断响应因子的区域可靠性电价。最后,计及用户差异化需求,基于单位可靠性增量成本制定了可靠性增量电价的定价方法。算例分析结果表明,由区域可靠性电价和增量电价相结合的定价体系能合理兼顾供电分区供电可靠性和用户差异化需求。

An analysis of quantitative PCR reliability through replicates using the C_(t)method

There is considerable interest in quantitatively measuring nucleic acids from single cells to small populations. The most commonly employed laboratory method is the real-time polymerase chain reaction (PCR) analyzed with the crossing point or crossing threshold (Ct) method. Utilizing a multiwell plate reader we have performed hundreds of replicate reactions each at a set of initial conditions whose initial number of copies span a concentration range of ten orders of magnitude. The resultant Ct value distributions are analyzed with standard and novel statistical techniques to assess the variability/reliability of the PCR process. Our analysis supports the following conclusions. Given sufficient replicates, the mean and/or median Ct values are statistically distinguishable and can be rank ordered across ten orders of magnitude in initial template concentration. As expected, the variances in the Ct distributions grow as the number of initial copies declines to 1. We demonstrate that these variances are large enough to confound quantitative classi?cation of the initial condition at low template concentrations. The data indicate that a misclassi?cation transition is centered around 3000 initial copies of template DNA and that the transition region correlates with independent data on the thermal wear of the TAQ polymerase enzyme. We provide data that indicate that an alternative endpoint detection strategy based on the theory of well mixing and plate ?lling statistics is accurate below the mis- classi?cation transition where the real time method becomes unreliable.

船舶行驶过程沉量可靠性预测研究

本文对船舶的航行过程进行分析,构建船舶的运动数学模型,并对船体的下沉量进行分析。基于CFD技术对船体下沉量进行数值分析,并给出船舶阻力数值模拟曲线和船舶下沉量数值模拟曲线,同时对船舶下沉量和流速之间的关系进行探讨;利用线性回归的方法对船舶的下沉量进行预测,对船中和船尾的下沉量和船体初始纵倾角之间的关系进行线性回归拟合预测。

《学生体质健康标准》中心血管功能评定指标的同质性和有效性的实验研究

为了分析《学生体质健康标准》中心血管功能评价指标的同质性和有效性,对87名普通大学生进行体质健康测试和最大耗氧量测试。研究结果表明,大学生的台阶测试得分和耐久跑成绩得分无显著差异;台阶测试得分与耐久跑之间无显著线性相关关系(r=-0.086,P>0.05);台阶测试和耐久跑指标之间无同质性;大学生最大耗氧量与台阶试验测试值和台阶试验得分无显著线性相关(r<0.15,P>0.05),大学生最大耗氧量与耐久跑成绩和得分之间也无显著线性相关。

乌克兰UGT25000燃气轮机试验运行经验及技术改进措施

UGT25000燃气轮机是由乌克兰研制的新型工业型燃气轮机，研制的2号机组于1995年11月-2001年6月在乌克兰“索菲亚”天然气增压站进行了工业试验运行。本文介绍了该机组的试验运行情况，在累计运行的25000h时间内，机组在低压压气机、低压涡轮和动力涡轮处出现了轴承损坏、裂纹等严重故障现象，说明机组在原型结构设计中存在一定的缺陷，可靠性达不到设计要求。为此在结构上进行了改进的设计，使得机组的使用寿命和可靠性有了较大的提高。这些措施在后续建造的机组中得到了应用。

中长跑训练系统可靠性问题的研究

对中长跑训练系统可靠性问题,从计划设计、训练过程中动态指标分析等方面进行探讨。认为要使训练系统具有稳定的可靠性,在设计训练计划时做到使计划的可靠性高于各个组成部分的可靠性;认真分析评价与训练系统有密切关系各项因素的单项可靠度。尽量减少或避免偶然因素和突发事件的发生。

大型电网运行可靠性理论及其应用综述

电网运行可靠性的分析是关系电网安全运行的关键课题。该文侧重大型电网的运行可靠性之“大”和“运行”两个特点,对可靠性理论和应用进行了研究、综述和展望,提出了可靠性算法中可以改进的若干措施,包括:从提高故障模式搜索速度、计及稳定性问题、采用复杂网络理论进行模型分析和连锁故障的预防控制、校正控制和紧急控制等;从隐藏故障角度分析由其引起的连锁故障;基于广域网测量的保护和安全控制系统的研究;FACTS装置对电网运行的影响等。

用步进法与升降法感度试验进行火工品安全性与可靠性验证的比较

本文对某型针刺雷管的两个批次分别进行了完全步进法及升降法感度试验。根据试验数据,计算同一刺激量下采用步进法与升降法得到的产品发火率,由Boltzmann模型拟合得到p——x曲线。根据曲线可知,在评价火工品安全性与可靠性时,升降法估计值比步进法偏乐观;当评估0.999响应点时,升降法较步进法对应的刺激量平均低约20%。

复杂分布仿真系统支撑环境的研究与开发

为促进不同领域、不同类型仿真应用的互操作与可重用,开发了基于高层体系结构接口规范1.3、具有良好实时性和可扩展性的运行时间框架软件———AST-运行时间框架,实现高层体系结构规范中的联邦管理、声明管理、对象管理、时间管理和数据分布管理。深入讨论了AST-运行时间框架的总体技术、时间管理、资源存储方案以及通讯机制,并进行了软件测试分析。介绍了AST-运行时间框架用于飞行模拟训练环境的应用实例。

铁路桥梁在地震作用下考虑行车安全的可靠度问题

本文提出了地震作用下列车正常行驶极限状态的概念，研究与之相应的最优可靠度问题。为了求出设计基准期内与最小总费用对应的可靠度(最优可靠度)，提出了一种简化方法，优化时采用了遗传算法和枚举法；用更新过程来描述损伤-修复过程，损伤指标用构件塑性铰处的最大曲率和极限曲率的比表示；以脱轨系数为依据判断列车能否正常行驶，采用响应面法求解失效概率。通过一算例求出了最优失效概率和相应的设计。

基于性能退化的小子样电主轴可靠性试验研究

针对高速电主轴可靠性研究存在的问题,探讨了小子样电主轴性能退化可靠性试验方法,完成了两根170MD18Y16型电主轴的退化试验;依据选定的性能退化特征量和截尾时间,检测了主轴轴端径向跳动量,据此建立试样电主轴退化模型,分析其失效寿命;基于跳动量测试数据和Weibull分布函数,应用修正极大似然函数分析分布参数,得到170MD18Y16型电主轴特征寿命,并确定其寿命分布模型。电主轴寿命理论值与实际使用值基本一致,表明小子样电主轴性能退化试验方法合理,建立的退化模型较准确地反映了电主轴性能退化轨迹,且寿命分布模型分析方法有效。