Innovative safety valve selection techniques and data

The new valve data resources and modeling tools that are available today are instrumental in verifying that that safety levels are being met in both current installations and project designs. If the new ISA 84 functional safety practices are followed closely, good industry validated data used, and a user's maintenance integrity program strictly enforced, plants should feel confident that their design has been quantitatively reinforced. After 2 years of exhaustive reliability studies, there are now techniques and data available to support this safety system component deficiency. Everyone who has gone through the process of safety integrity level (SIL) verification (i.e. reliability math) will appreciate the progress made in this area. The benefits of these advancements are improved safety with lower lifecycle costs such as lower capital investment and/or longer testing intervals. This discussion will start with a review of the different valve, actuator, and solenoid/positioner combinations that can be used and their associated application restraints. Failure rate reliability studies (i.e. FMEDA) and data associated with the final combinations will then discussed. Finally, the impact of the selections on each safety system's SIL verification will be reviewed.     

Extending the Possibilities of Quantitative Determination of SIL – a Procedure Based on IEC 61508 and the Markov Model with Common Cause Failures

Generalized equations for calculating the probability of failure on demand (PFD) in accordance with the IEC 61508 standard and a model based on Markov processes, taking into account common cause failures, are proposed in this paper. The solutions presented in the standard and in many references concentrate on simple k‐out‐of‐n architectures. The equations proposed in the standard concern cases for n ≤ 3. In safety‐related systems applied in industry, architectures of a number of elements n larger than three often occur. For this reason, a generalized equation for calculating PFD was proposed. For cases presented in the standard, the proposed equation provides identical results. The presented simplified Markov model allows the determination of the system availability (A(t)) and unavailability (1–A(t)) as well as their values in the steady state (A and 1–A). This model can be an alternative method of PDF calculations for various k‐out‐of‐n architectures with self‐diagnostic elements. Calculations performed according to the proposed models provide very similar results. The developed models are suitable for practical implementations in calculations of the safety integrity level. Copyright © 2016 John Wiley & Sons, Ltd.     

基于多波束测深声呐的海底气体泄漏实时报警系统

随着人们对海底油气资源的开发,在海底铺设的管道越来越多,海底管道泄漏风险日益增加,亟需高效、实时的检测方法。文章利用自主式水下航行器(Autonomous Underwater Vehicle, AUV)平台,搭载多波束测深声呐与基于VxWorks的嵌入式处理单元,设计了一套水下气体泄漏自动检测系统,将多波束测深声呐采集的水体图像数据传送给嵌入式处理单元,采用模板匹配方法对图像数据进行处理,完成对海底管道气体泄漏点的实时检测。湖试和海试都验证了该系统方案的有效性与先进性。     

Criticality and sensitivity analysis of the components of a system

In the design of complex systems there is a great interest to know the relative importance of each of their elements. In this paper, we define a new method for measuring the relative importance of each element of the system. We have to specify that this paper concerns only non-repairable systems and components. We present a way of calculating the criticality of each component for a complex system no matter what the random distribution of the life of the component is. The paper also demonstrates a simple way of calculating how the system life improves when the life of a component is improved.     

环境噪声对语言识别率的影响

本文比较了４种干扰声源声级（ｄＢＡ）和语言干扰级（ＳＩＬ）的关系，观察了不同ｄＢＡ，ＳＩＬ和信噪比（Ｓ／Ｎ）对语言识别率影响的规律，结果表明ｄＢＡ与ＳＩＬ有很好的线性关系，但不同性质的噪声源，两者间的差值相差很大，４种干扰声源下的语言识别率都有随ｄＢＡ和ＳＩＬ的增加而减少，随ＳｄＢＡ／ＮｄＢＡ和ＳｄＢＡ／ＮＳＩＬ的增加而提高的趋势，但语言识别率与ｄＢＡ，ＳｄＢＡ／ＮｄＢＡ的相关性因噪声的性质不同有     

基于语音交互功能的医疗服务机器人控制系统设计

根据老年人、残疾人的实际需求,设计了医疗服务型机器人移动本体和6自由度机械手臂,搭建了以简化隐式马科夫模型为基础的自动语音辨识控制系统。该控制系统通过人机交互系统的语音命令与键盘指令,可控制机器人运行到指定位置,控制机械手抓取物体,实现机器人的避障功能和座椅、病床两模式的自主切换。针对典型医疗服务需求,对所设计的医疗服务机器人进行了实验,实验结果表明,该机器人在人机交互指令控制下能很好地实现到达指定位置、抓取物体、避障和病床/座椅模式切换,不仅易于操作,而且性能稳定,语音系统对命令的识别率达90%以上,从而验证了该医疗服务型机器人控制系统设计的可行性和有效性。     

基于统计能量法的排气管道系统的振动和噪声分析与研究

基于统计能量分析(SEA)原理,结合压缩机排气管道系统的实际结构尺寸建立了SEA模型。采用理论及经验结果讨论了统计能量分析法三个重要参数确定,利用现场测试壳体加速度来确定输入功率。运用AutoSEA2004仿真软件预测了距离管道系统外部一定距离的声压级,并与现场测试所得数据进行了对比分析,结果表明,预测管道系统的总声压级为102.7dB(A),比实测结果低4.2dB(A),在500 Hz以上主要频段上,预测曲线与实测曲线吻合较好,为管道系统噪声治理提供了数值仿真依据。     

On-line tuning system of multivariate dEWMA control based on a neural network approach

The double exponentially weighted moving average (EWMA) controller is a popular algorithm for on-line quality control of semiconductor manufacturing processes. The performance of the closed-loop system hinges on the adequacy of the two weight parameters of the double EWMA equations. In 2004, Su and Hsu presented an approach based on the neural technique for ‘on-line’ tuning the weight of the single EWMA equation in the single-input single-output (SISO) system. The present paper extends the neural network on-line tuning scheme to the double EWMA controller for the non-squared multiple-input multiple-output (MIMO) system, and validates the control performance by means of a simulated chemical–mechanical planarization (CMP) process in semiconductor manufacturing. Both linear and non-linear equipment models are considered to evaluate the proposed controller, coupling with the deterministic drift, the Gaussian noise and the first-order integrated moving average (IMA) disturbance. It has been shown from a variety of simulation studies that the proposed method exhibits quite competitive control performance as compared with the previous control system. The other merit of the proposed approach is that the tuning system, if sufficient training in a neural network is available, can be practicably applied to complex semiconductor processes without undue difficulty.     

Design optimization of a safety-instrumented system based on RAMS+C addressing IEC 61508 requirements and diverse redundancy

This paper presents the design optimization by a multi-objective genetic algorithm of a safety-instrumented system based on RAMS+C measures. This includes optimization of safety and reliability measures plus lifecycle cost. Diverse redundancy is implemented as an option for redundancy allocation, and special attention is paid to its effect on common cause failure and the overall system objectives. The requirements for safety integrity established by the standard IEC 61508 are addressed, as well as the modelling detail required for this purpose. The problem is about reliability and redundancy allocation with diversity for a series-parallel system. The objectives to optimize are the average probability of failure on demand, which represents the system safety integrity, Spurious Trip Rate and Lifecycle Cost. The overall method is illustrated with a practical example from the chemical industry: a safety function against high pressure and temperature for a chemical reactor. In order to implement diversity, each subsystem is given the option of three different technologies, each technology with different reliability and diagnostic coverage characteristics. Finally, the optimization with diversity is compared against optimization without diversity.     

Early failure analysis of machining centers: a case study

To eliminate the early failures and improve the reliability, nine ex-factory machining centers are traced under field conditions in workshops. Their early failure information throughout the ex-factory run-in test is collected. The field early failure database is constructed based on the collection of field early failure data and the codification of data. Early failure mode and effects analysis is performed to indicate the weak subsystem of a machining center or the troublemaker. The distribution of the time between early failures is analyzed and the optimal ex-factory run-in test time for machining center that may expose sufficiently the early failures and cost minimum is discussed. Suggestions how to arrange ex-factory run-in test and how to take actions to reduce early failures for machining center is proposed.     

基于浸入与不变原理的电力系统混沌振荡分析与控制

针对电力系统中普遍存在的参数变化引起系统混沌振荡导致系统不稳定问题,提出了一种基于浸入与不变(immersion and invariance,Ⅰ&Ⅰ)原理的自适应反演滑模控制(adaptive backstepping sliding mode control,ABSMC)算法,以提高电力系统运行稳定性.首先,利用电...     

应用希尔伯特黄变换的单矢量传感器多目标分辨研究

将希尔伯特黄变换与矢量信号处理相结合应用到水声领域,与传统方法相比有许多优势。在希尔伯特黄变换中本征模态函数是基于序列数据的局部时间尺度特征而得出。每个本征模态函数可以看作是信号中一个固有振荡模态,其对应于某个目标的固有振荡,希尔伯特黄变换用经验模态分解的方法将信号分解为多个本征模态函数,可以较好地将不同目标的能量分离。该变换得到的瞬时频率、瞬时能量和瞬时方位具有清晰的物理意义,信号的时间-频率-方位-能量的四维分布为多目标信号处理提供了丰富的信息量。与传统处理方法相比不仅有较好的目标分辨效果,而且适用于非线性和非平稳信号的处理。     

基于TRIZ的AFD失效分析方法

预期失效分析(anticipatory failure determination,AFD)是在TRIZ基础上发展起来的一种失效分析方法,通过反向思维将TRIZ中的发明问题解决算法(ARIZ)逆向应用于失效分析,并集成应用了TRIZ中的冲突分析与解决工具消除失效隐患。AFD主要应用于产品设计中的失效预测分析。给出了AFD方法的原理及应用于失效预测的详细工作流程,分析了在中药滴丸机设计过程中应用AFD进行失效预测分析的一个实例。     

Agile manufacturing system control based on cell re-configuration

The control of an agile manufacturing system (AMS) is expected to be flexible, open, scalable and re-configurable so as to tackle the more complex and uncertain information flows. To meet these requirements, we propose agent-based control architecture for AMS, under which the functions of task planning, scheduling and dynamic control are integrated seamlessly. First of all, this paper introduces the concept of RMC (re-configurable manufacturing cell), based on which, we construct the control architecture for AMS in compliance with multi-agent system (MAS). The whole control process under the architecture comprises two hierarchies, i.e. the upper one for order planning and RMC forming and the lower one for task scheduling within each RMC. For the upper hierarchy, we establish a linear integer programming (LIP)-based mathematical model and a MAS-based dynamic process model, and present a two-step approach to order planning and RMC forming. For the lower hierarchy, we develop the scheduling model, a method based on the bidding mechanism from contract net, and describe the rescheduling mechanism in the control system. To illustrate the methodology proposed in the paper, a simulation study is thoroughly discussed. Our studies demonstrate that the RMC-based control architecture provides an AMS with an optimal, dynamic and flexible mechanism of responding to an unpredictable manufacturing environment, which is crucial to achieve agility for the whole manufacturing system.     

Study on reliability modelling of a hydraulic excavator system

The failure patterns of a well-known brand of a hydraulic excavator system used in different environments were modelled adequately with an NHPP (non-homogeneous Poisson process) having time-dependent log-linear peril rate functions. Using the fitted model, the reliability of the excavator system was estimated in different environments (cement plant, coal mine, iron ore mine, etc.). The system reliability was found to be very poor during the initial phase of operation and gradually improved with an increase in cumulative operating hours regardless of change in environment. Notwithstanding this general trend, the system reliability differed significantly in different environments for any given duration of operation and was particularly very poor in cement plants. With the help of the FMEA technique, high risk prone failure modes of the excavator system of the given model were identified and appropriate corrective measures were initiated. The failure patterns of the modified excavator system changed regardless of environment, so much so that an HPP (homogeneous Poisson process) model with constant peril rate could be fitted adequately to characterize the failure pattern of the system. The system reliability improved considerably in the initial phase of operation since start-up.     

基于EMD和HHT的航空发动机转子—机匣振动信号分析

将EMD和HHT方法引入航空发动机转子—机匣的振动信号分析,某台发动机的台架实测机匣振动信号的分析结果表明,该方法能够比较清楚地再现转静系统碰摩故障随转速和采样周期的演变过程,能够克服傅立叶谱无法同时获得时域和频域信息的缺陷。同时边际谱与傅立叶谱相比能够比较真实客观地反映系统的频率和幅值分布情况。     

基于SQL Server的脑电数据库的构建

基于SQL Server 2000,构建了一个脑电数据库系统,并配置了一个IIS(Internet Information Services)服务器以方便网络查询(http://202.113.232.103:8088/neurodb/).以临床脑电数据为例,该数据库不仅存储了病例信息,还将脑电数据及其注释结构化和规范化为数据库的表的形式.这与通常采用的文本文件的存储方式不同,它能够充分发挥关系型数据库的强大优势,为存储、检索和分析数据带来最大程度的方便和灵活性,减少错误的发生.与此同时,为数据库还开发了一个相关软件,用于展示脑电图.软件中集成了多种算法,可直接进行数据分析.论文介绍了该数据库的设计、相关软件的开发,并列举了一些数据库的应用.     

Biaxial testing and analysis of bicycle-welded components for the definition of a safety standard

ABSTRACT This paper presents the experimental evaluation of the fatigue behaviour of welded components under non‐proportional variable amplitude biaxial loads. The study was undertaken on welded mountain bike handlebar stems, which were different in terms of geometry and technology and tested with load histories that were reconstructed and accelerated from recorded field data. Loads measured in the field were decomposed into bending and torsional components; a synchronous Peak‐Valley counting, a spectrum inflation technique, a spline interpolation and a final amplification were applied to the measured signals in order to obtain test drive signals with the correct content of biaxial non‐proportional loadings. After evaluation of the bending and torsion load‐life curves of components under constant amplitude fatigue, the resulting data from biaxial variable amplitude fatigue tests were analysed in order to evaluate the damage contribution as a result of the two load components and an equivalent simplified two‐stage constant amplitude fatigue test was proposed to the working group ISO/SC1/TC149/WG4.     

An integrated product service system modelling methodology with a case study of clothing industry

Product-service system (PSS) is a business model designed to help enterprises achieve servitisation. PSS not only considers service-oriented logic to increase product value but also supports enterprises with waste reduction. An increasing number of studies have emphasised PSS development. However, much of the literature remains focused on separate development phases, such as idea generation or a specific product or industry application. An integrative system modelling methodology designed to help companies formulate a complete scenario is absent. This study provides a methodology for developing a systematic and complete PSS strategy. It combines failure modes and effects and importance-performance analysis to identify potential customer needs. A service-product development matrix and a product-service life cycle analysis are developed. Following the service concepts generation, grey relational analysis and scenario analysis are utilised to evaluate the alternatives. A case study involving the clothing industry was conducted to test the proposed approach. Results indicate the methodology can help service providers identify existing problems and develop service alternatives systematically. These alternatives can then be evaluated and the scenario which achieves the highest profitability, is the most environmental friendly, and is the most social friendly can be identified.     

Time-varying FMEA method based on interval-valued spherical fuzzy theory

This paper proposes a time-varying failure mode and effect analysis (FMEA) method based on interval-valued spherical fuzzy theory, which not only improves the limitations in evaluating, weighting, and ranking but also considers the effect of time change. The process of distinguishing time changes enables the FMEA to have dynamic recognition capability, enabling it to identify critical failure modes more accurately. The interval-valued spherical fuzzy theory is used to deal with the uncertainty of intuitionistic linguistic evaluations. The advantages of two traditional approaches are combined to improve the weight determined method. Risk factors are divided into subjective and objective types. In the subjective risk factors, which are severity (S) and detection (D), the consistency of judgment is used as the acceptance standard. In the objective risk factors, which are occurrence (O), the time-varying characteristics are considered. The occurrence in a certain period is expressed as the integral of failure intensity in the time period. Interval-valued spherical fuzzy exponential risk priority number is proposed as the criterion for measuring the priority of failure modes. The effectiveness of the proposed method is verified using an example of spindle.