基于故障树的永磁直驱风力发电机组故障分析

随着风力发电机组功率的增加,其结构的复杂性也随之提高,伴随着运行时间的增加,运行过程中产生的故障日益增多,迫切需要对机组运行过程产生的故障进行分析。基于此,该文提出了利用故障树分析方法,结合某型永磁直驱风力发电机组运行期间产生的故障事件数据建立故障树模型,并对模型进行定性和定量分析,得出了风机运行故障事件的关键重要度及相关部件系统的重要度,对提高风机运行的可靠性,提高风电场的运维准确性具有指导意义。     

基于动态故障树的CTCS-3级ATP系统可靠性分析简

 针对传统的可靠性分析方法分析CTCS-3级ATP系统动态失效问题的不足,提出采用动态故障树分析其可靠性。首先,分析系统的结构和功能建立动态故障树模型;其次,采用深度优先最左遍历算法搜索动态故障树模型,得到独立的子树;最后,在引入可修系统可靠性指标基础上,采用解析法和马尔科夫矩阵迭代法求解子树,结合分层迭代方法对动态故障树分析法改进,以减小运算量,使得上述可靠性指标能用于CTCS-3级ATP系统的可靠性评估。计算所得可靠性指标与可靠性框图分析得到的结果对比表明：动态故障树能够更好地描述系统的冗余性和容错性等特点,提高了可靠性指标的精度。     

多部件系统机会维修优化模型

针对系统部件间存在经济相关性的情况,利用更新过程理论建立了机会维修策略下的多部件系统可靠性模型,并提出了求解系统期望维修费用率和稳态可用度的解析方法.在此基础上,以系统期望维修费用率最低为优化目标,稳态可用度满足要求为约束条件,通过非线性规划优化方法得到了系统的最佳机会维修阈值τ*.最后通过分析优化模型中不同变量与维修阈值之间的相互影响关系,讨论了不同维修策略的适用范围.     

基于故障树分析的汽车空调系统故障诊断研究

介绍基于故障树分析的故障判断方法,以桑塔纳VISTA轿车空调系统故障诊断为例,建立系统不制冷故障树模型,并进行故障排查与分析,为汽车空调系统的维修与维护提供依据。     

药品智能包装的模糊灰色故障树分析

目的对某款药品智能包装从系统层面进行可靠性分析。方法首先,通过失效分析建立药品智能包装的故障树;其次,利用专家判断知识和模糊数学理论,得到故障树底事件和顶事件的三角形式模糊失效率,以及采用模糊中值法进行底事件模糊重要度计算;最后,运用灰色关联分析求出表征各最小割集与顶事件相关行为关系的灰色关联度。结果定量分析计算显示,药品智能包装模糊失效率为(0.146 59,0.179 69,0.206 91),故障相关性最大的为包装材料本身的功能失效,其次为外界的振动和冲击以及包装尺寸误差等。结论模糊灰色关联故障树同时考虑包装系统的模糊性和灰色性,它可为预防药品智能包装失效、提高智能包装可靠性和安全性提供理论依据。     

多柔性体系统振动问题分析研究

在以往单柔性体系统振动研究和柔性多体系统动力学理论的基础上,对包含多个柔性体在内的机械系统振动响应进行分析。通过使用ANSYS和ADAMS软件建立以曲轴活塞机构为代表的系统动力学模型,然后使用柔性体代替机构中的不同部件进行振动响应比较计算的方法,得到系统中柔性体变化与系统整体振动响应变化之间的基本规律。这些规律能够为大型系统级振动分析模型的简化和计算精度保证提供必要的参考。     

某转管机枪机心部件动力学特性分析与改进研究

以某型转管机枪为研究对象,为了分析解决该型机枪在样机试验中出现的机心头断裂、机心卡死以及闭锁开锁时接触面强度不足等故障现象,首先对机心部件开闭锁过程进行了受力分析;其次利用多体动力学分析软件建立了机枪系统的动力学模型,重点对机心运动过程进行了动力学计算;然后利用有限元分析软件建立了机心部件运动过程中的动态应力与位移分析模型,在满足机枪射频要求的前提下,得出开闭锁过程中接触面关键位置的应力与位移的变化曲线;最后综合研究分析得到的动力学响应特性和应力、位移云图,分析找出引发故障的根本原因,对机心头进行了结构改进,有效提高了机枪的射击可靠性,为机心部件的优化改进提供了理论依据与试验指导。     

基于模糊故障树的军用气象物资包装可靠性分析

应用模糊故障树分析方法对军用气象物资包装可靠性进行了系统分析,简要介绍了模糊故障树分析方法的基本理论,利用专家判断和模糊集理论相结合的方法,评估了故障树底事件发生的模糊失效概率。并以"TFS-1通风干湿表包装"为例,建立了包装系统的故障树,采用下行法求解了引起顶事件发生的最小割集,定量分析计算,得出模糊失效率为0.0705,同时计算了各底事件的重要度。模糊故障树分析方法对于提高军用气象物资包装防护能力,确保物资装备质量,具有非常重要的意义。     

脚踝康复机器人的可靠性评估

本文首先对脚踝康复机器人的结构和功能进行分析,描述脚踝康复机器人各功能单元的相互依赖关系。建立脚踝康复机器人故障树,通过故障树的定性和定量分析,得到故障树底事件的相对概率重要度,从而确定关键零部件及其故障模式。建立脚踝康复机器人的可靠性数学模型及可靠性框图,并计算得到脚踝康复机器人系统基本可靠度。本文探索了一种比较实用、高效的脚踝康复机器人可靠性评估方法,为脚踝康复机器人可靠性设计提供依据。     

双制冷循环电冰箱的计算机仿真

本文以一台双制冷循环电冰箱为对象,在分析制冷系统及其部件的动态特性的基础上,建立了制冷系统的动态仿真模型及箱体的传热模型,通过比较计算与实验的结果,证实了模型的可靠性。用本文的模型,研究了制冷系统部件之间匹配与功耗的关系,进而进行了优化分析。指出了系统匹配的优化方向,并对所得之优化结论进行了实验验证。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.