Optimizing reliability, maintainability and testability parameters of equipment based on GSPN

Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and optimizing the three properties are of great significance. A new approach for optimization of RMT parameters is proposed. First of all, the model for the equipment operation pro- cess is established based on the generalized stochastic Petri nets （GSPN） theory. Then, by solving the GSPN model, the quantitative relationship between operational availability and RMT parameters is obtained. Afterwards, taking history data of similar equipment and operation process into consideration, a cost model of design, manufacture and maintenance is developed. Based on operational availability, the cost model and parameters ranges, an optimization model of RMT parameters is built. Finally, the effectiveness and practicability of this approach are validated through an example.

PROBABILITY OF RANDOM EVENTS OF INSPECTION AND REPAIR AND MAINTAINING RELIABILITY OF STRUCTURES

Reliability analysis of the inspected and repaired structure requires dealing with a large number of complex random events. Considering many kinds of random factors, a probability of these random events existing possibly in the inspection and repair process and reliability analysis methodologies are proposed. A systematic dynamic reliability model is given for structures in service under the scheduled inspection and repair.

The Effect of Active Knee Extension in Sitting on Lumbopelvic Curvature in Individuals with Clinically Tight Hamstring Muscles: A Cross-Sectional Reliability Study

Relative flexibility between the hamstring and lumbar extensor muscles, which can be evaluated using lumbopelvic curvature during active knee extension in sitting, can sometimes be assessed in physical therapy. However, reliability for its quantitative measure has not been established yet and its establishment was the aim of the current study. Twenty-seven individuals with clinically tight hamstring muscles were recruited. On two separate sessions, the lumbopelvic curvature was evaluated in sitting when the right knee was moved from 90&deg flexion to 10&deg flexion on 15 occasions using a flexible ruler by two examiners on Day 1 and one on Day 2. Lines drawn tangential to the lumbopelvic curvature were traced at T12 and S2 vertebral levels and the angle between the two vertical lines was calculated. Using Day 1 data, the minimum number of repetitions and inter-examiner reliability were assessed. Inter-session reliability was also examined. As a result, there was no statistical difference (P?> 0.05) in the mean absolute difference between the mean value of N-1 and N repetitions (6 ≤ N ≤ 15) in the lumbopelvic curvature angle, indicating that five was considered the minimum number of repetitions. Intraclass correlation coefficient (ICC)(1, 5)?for the inter-session reliability and ICC(2, 5)?for the inter-examiner reliability was 0.97 and 0.93, respectively, indicating excellent reliability. The measure for the lumbopelvic curvature during active knee extension in sitting, which was established in the current study, will be a foundation for further research regarding the relative flexibility of the lumbar and adjunct regions.

Measurement Reliability for Evaluating Lumbopelvic Curvature during Active Knee Extension in Sitting Using a Flexible Ruler in Individuals with Clinically Tight Hamstring Muscles: A Secondary Analysis

In a previous study, we established reliability of a method for determining the angle of lumbopelvic sagittal alignment during active knee extension in sitting (AKEiS) using a flexible ruler and image analysis software (2-point-Method). In addition to this method, a flexible ruler can also be used to measure lumbopelvic sagittal alignment without image analysis software. This study primarily aimed to investigate the minimum number of repetitions, inter-session reliability and inter-examiner reliability of two alternative methods of measurement in a secondary analysis of our previous study. A flexible ruler was used to measure lumbopelvic curvature during AKEiS when the knee reached 10° flexion from 27 individuals with clinically tight hamstring muscles and subsequently analyzed. Lumbopelvic sagittal alignment was evaluated for the region between T12 and S2 using the maximum depth to the curvature (Max-Method) or depth to the curvature at the middle point between T12 and S2 vertebral levels (Mid-Method). It was determined that four repetitions for the Max-Method and 11 repetitions for the Mid-Method were required for the minimum number of repetitions, respectively. Inter-session reliability and inter-examiner reliability were assessed using Intraclass Correlation Coefficients and were 0.91 and 0.91 for the Max-Method and 0.90 and 0.91 for the Mid-Method, respectively. The current study suggests that the Mid-Method would not be recommended for use in the clinical setting as 11 repetitions of data sampling is required. The 2-point-Method or Max-Method may be promising but the ideal measurement method will be identified when the validity of these methods has been established.

Significant Factors for Reliability Estimation of Component Based Software Systems

Software reliability is defined as the probability of the failure-free operation of a software system for a specified period of time in a specified environment. Traditional approaches for software reliability analysis are black box approaches. These approaches use the software as a whole. At present, main emphasis of software is on reuse, hence component based software applications came into existence. Black box models are not appropriate for these applications. This paper introduces some significant factors for reliability estimation of Component Based Software Applications. Reliability of Component Based Software Application depends upon these factors. This paper?also gives the definition of factors and explains its relation with reliability of software application.

Extremum response surface method of reliability analysis on two-link flexible robot manipulator

In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.

Strategy for Synthesis of Flexible Heat Exchanger Networks Embedded with System Reliability Analysis

System reliability can produce a strong influence on the performance of the heat exchanger network(HEN).In this paper,an optimization method with system reliability analysis for flexible HEN by genetic/simulated annealing algorithms(GA/SA) is presented.Initial flexible arrangements of HEN is received by pseudo-temperature enthalpy diagram.For determining system reliability of HEN,the connections of heat exchangers(HEXs) and independent subsystems in the HEN are analyzed by the connection sequence matrix(CSM),and the system reliability is measured by the independent subsystem including maximum number of HEXs in the HEN.As for the HEN that did not meet system reliability,HEN decoupling is applied and the independent subsystems in the HEN are changed by removing decoupling HEX,and thus the system reliability is elevated.After that,heat duty redistribution based on the relevant elements of the heat load loops and HEX areas are optimized in GA/SA.Then,the favorable network configuration,which matches both the most economical cost and system reliability criterion,is located.Moreover,particular features belonging to suitable decoupling HEX are extracted from calculations.Corresponding numerical example is presented to verify that the proposed strategy is effective to formulate optimal flexible HEN with system reliability measurement.

Research on the Reliability Centered Maintenance Plan of a Launching System

Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.

Design and reliability,availability,maintainability,and safety analysis of a high availability quadruple vital computer system

With the development of high-speed railways in China,more than 2000 high-speed trains will be put into use.Safety and efficiency of railway transportation is increasingly important.We have designed a high availability quadruple vital computer (HAQVC) system based on the analysis of the architecture of the traditional double 2-out-of-2 system and 2-out-of-3 system.The HAQVC system is a system with high availability and safety,with prominent characteristics such as fire-new internal architecture,high efficiency,reliable data interaction mechanism,and operation state change mechanism.The hardware of the vital CPU is based on ARM7 with the real-time embedded safe operation system (ES-OS).The Markov modeling method is designed to evaluate the reliability,availability,maintainability,and safety (RAMS) of the system.In this paper,we demonstrate that the HAQVC system is more reliable than the all voting triple modular redundancy (AVTMR) system and double 2-out-of-2 system.Thus,the design can be used for a specific application system,such as an airplane or high-speed railway system.

Flexible carbon nanotube-enriched silver electrode films with high electrical conductivity and reliability prepared by facile screen printing

Flexible electrode films play critical and fundamental roles in the successful development of flexible electronic devices. In this study, carbon nanotubes（CNTs） were implanted into silver（Ag） ink to enhance the electrical conductivity and the reliability of the printed Ag electrode films. The fabricated carbon nanotubes-enriched silver（Ag-CNTs） electrode films were printed on the polyimide substrates by a facile screen printing method and sintered at a relatively low temperature. The resistivity of Ag-CNTs films was decreased by 62.27% compared with the pure Ag film. Additionally, the Ag-CNTs films exhibited excellent flexibility under a bending radius of 4 mm（strain ε = 2.09%） over 1000 cycles. Furthermore, the Ag-CNTs film displayed unchangeable electrical conductivity together with a strong adhesion after an accelerated aging test with 500 thermal shock cycles. These improvements were attributed to the AgCNTs interconnected network structure, which can provide electronic transmission channels and prevent cracks from initiating and propagating.

基于柔顺性的血管支架优化设计及强度可靠性分析

目的建立血管支架的参数化模型,进行血管支架柔顺性能的优化设计。基于优化结果考虑加工精度引起的设计尺寸的不确定性,进行血管支架强度的概率计算以验证优化结果的可靠性。方法探寻结构特征,建立血管支架参数化模型。取弯曲刚度作为优化目标,血管支架支撑筋宽度、支撑筋长度、连接筋宽度和支架厚度为设计变量,采用响应面法进行血管支架优化设计,选取应力局部灵敏度较低的候选设计点作为最优设计点。基于优化血管支架,取受加工精度影响的设计尺寸作为随机变量,利用六西格玛工具进行血管支架强度的概率计算。结果建立了参数化的血管支架模型,优化后的血管支架弯曲刚度相比原始血管支架减小32.91%,累积分布概率为99.85%时,血管支架最大应力满足强度条件。结论连接筋宽度对血管支架的柔顺性影响最大,支架厚度次之,支撑筋长度和宽度影响较小;加工精度影响下优化血管支架强度可靠。血管支架在工程实际中会受到一些不确定性因素的影响,在进行确定性优化设计之后,要考虑不确定性因素引起的设计变量的不确定性进行强度可靠性分析验证。

光绪前期厘金用款的严控限制与督抚筹对

厘金是咸丰初年清廷应对战时财源枯竭,持续支持战时财政而开发的新式财源。自咸丰初期迄光绪前期,厘金财源的扩张收入支持着大规模战争的军费支出,各类善后事业和洋务新政也得以挹注支撑。基于部库收支拮据的严峻现实,清廷自光绪六年对各省厘金用款比例实行严控,各省对此抵触筹对,或暗中敷衍应付,或奋起顶奏维权。双方基于自身视野和利益,均秉持“守经达权”的决策理念,却在实际上逐步走向彼此疏离。近代秉政治国者如何贯通“守经”与“达权”,有机衔接这两种逻辑,既考验着昔日的帝王僚臣,也为今人如何守制创新提供了鉴戒。

一种基于UVM的USB接口验证平台设计

随着集成电路的发展,电子设备变得越来越复杂,对于通用串行总线(Universal Serial Bus,USB)接口的验证来说,传统的验证方法已经无法满足需求。使用通用验证方法学(Universal Verification Methodology,UVM)验证平台可以提高验证效率,减少人工操作和误差,保证USB设备的品质和可靠性。本文介绍了一种基于UVM的USB接口验证平台设计,该平台可以对USB接口进行模块化和可重用性设计,支持自动化测试流程,测试数据的收集和分析等功能。通过应用UVM验证平台,针对USB接口传输方式对其单次传输过程进行封装并继承使用,加速USB设备的开发和测试进程,提高产品质量和生产效率。实验结果表明,与传统的验证方法相比,使用UVM验证平台可以显著提高验证效率和精度。此外,该平台还具有高可靠性和高可维护性,可广泛应用于各种USB设备的开发与生产过程中。

具备系统重构能力的机载信息系统硬件设计方案

机载信息处理系统,与机载航电系统、任务电子系统及通信系统相连,实现对接入的各系统的管理与控制,具有十分重要的作用,因此,系统的任务可靠性显得尤为重要,确保在部分功能失效时,即使降低系统性能,整个系统也能够完成任务。基于此要求,本文权衡了技术指标、可靠性、重量、体积、费用等因素,提出了具有系统重构能力的基于柔性重组的硬件设计方案,以较低的成本实现了较高的任务可靠性。

基于期望任务寿命的可重复运载火箭RMT参数规划模型研究

随着世界航天领域科技的高速发展,可重复运载火箭一直是国内外的研究热点。伴随着该技术的蓬勃发展,高可靠性、高安全性、高质量成为新一代运载火箭设计目标,在可重复运载火箭的高可靠性背景下,对系统的可靠性、维修性、测试性的相关指标进行设计与参数规划显得尤为重要。针对上述问题,综合运用可靠性工程理论、可用度、马尔可夫状态转移过程理论等等,准确地对可重复运载火箭的发射过程进行解析,并且根据复杂装备的指标要求,对其进行分析与研究,最终得到一个较为可靠的可重复运载火箭RMT指标的参数规划模型。

空间挠性作动器的可靠性验证试验方法

为了对空间挠性作动器在轨运行的可靠性进行评估,针对作动器在轨工况复杂、小子样、长寿命的特点,给出了作动器可靠性验证试验方法。首先,在分析作动器结构组成及工作原理的基础上,确定了作动器可靠性特征量。然后,以寿命型可靠性试验为基本思路,针对挠性元件在轨疲劳断裂失效这一主要故障模式,根据在轨典型工况载荷数据进行疲劳试验载荷谱设计,采用试验载荷谱开展挠性元件加速疲劳寿命试验,基于试验结果给出作动器的可靠性评估结果。最后,以某型号空间挠性作动器为例,基于挠性元件加速疲劳试验进行可靠性试验验证,得到作动器可靠性评估结果。研究结果表明,该作动器可靠度满足指标要求,评估结果符合工程实际。运用所提出的可靠性验证试验方法,可为空间挠性作动器在轨运行可靠性的定量评估提供有效的技术途径,可为航天器运动机构的可靠性验证提供参考。

一种灵活可靠的IGBT驱动电路设计

在当今减碳排放背景下,全控型功率器件IGBT以优异的性能广泛用于各种变流器中,有效可靠的驱动电路对IGBT的安全工作至关重要,特别是大功率应用场合。针对大功率IGBT应用中对驱动电路灵活可靠的要求,设计了一种基于智能集成光耦驱动器ACPL-332J的IGBT驱动保护电路,分析了ACPL-332J的各项参数,并以ACPL-332J为核心设计了驱动电路。以英飞凌FF600R12ME4为应用IGBT,通过双脉冲试验、短路试验验证了设计电路驱动及保护的有效性。

基于改进FMECA与维修性的数控机床可靠性分配方法

FMECA方法可有效指导数控机床的可靠性分配,但是分析过程中忽略了决策专家决策随机性和模糊性以及子系统维修性的影响。因此,提出一种改进FMECA与维修性的数控机床可靠性分配方法。在子系统危害性分析过程中,利用云模型定量表示决策专家的评价值,有效解决了决策专家评价过程中随机性和模糊性对评价结果的影响。考虑维修性因素的影响,建立基于云模型的改进RPN方法(C-RPN),实现了数控机床子系统可靠性的合理分配。并通过与传统方法进行对比,说明了所述方法的优势。

强风多发区柔性光伏支架抗风可靠度评估

以某实际柔性光伏支架为研究对象,建立了该光伏支架的有限元模型,并通过实测结构动力特性验证模型的正确性.采用谱表示-降维方法,生成全概率空间内的随机风速代表性样本集合.在此基础上,结合概率密度演化理论,研究了基本风速、风荷载方向及支撑索预拉力对其位移响应及抗风可靠度的影响.结果表明:随着风速的增大,柔性光伏支架抗风可靠度降低,当基本风速达到25 m/s时,结构平均整体抗风可靠度仅为0.14;提高支撑索预拉力可以显著提升结构抗风可靠度,但随着预拉力的增大,预拉力对抗风可靠度的提升作用越来越小;与背风荷载相比,柔性光伏支架在承受正风荷载时,结构抗风可靠度更低,预拉力对抗风性能的提升效果更显著.

基于电压行波波形特征的柔性直流输电线路雷击识别方法

柔性直流输电系统的线路主保护速动性要求极高,线路受雷击干扰后引入大量高频暂态信号易引发线路保护误动作。针对此问题,首先根据行波的传播规律分析雷击后线路电压行波特征,得出雷击干扰与故障的特征差异。雷击干扰时,暂态过程中电压行波经线路边界反射后波头极性不发生改变,行波波头到达线路边界的时间间隔大。雷击故障时,电压行波经故障点反射后波头极性发生改变,行波波头到达线路边界的时间间隔小。然后,根据电压行波波形特征差异提出长短窗结合的雷击干扰识别方法。最后,利用PSCAD/EMTDC电磁暂态仿真软件对所提方法进行验证。结果表明,所提出的雷击干扰识别方案能够快速、可靠、准确地识别雷击干扰与故障情况,不受雷击位置、线路参数、雷电流参数和噪声的影响。