CoBTx-Net: A model for business collaboration reliability verification

Collaborative business process can become unreliable when business partners collaborate in a peer- based fashion without central control. Therefore, reliability checking becomes an important issue that needs to be dealt with for any generic solution in managing business collaboration. In this paper, we propose a novel Choreographical Business Transaction Net (CoBTx-Net) to model collaborative business process and to manage the collaboration by individual participants. Furthermore three reliability properties named Time-embedded dead marking freeness, Inter-organizational dead marking freeness, and Collaborative soundness are defined based on CoBTx-Net to verify (1) the violation of time constraint, (2) collaborative logic conflicts, and (3) the improper termination from individual organizations.

基于PCC控制的变频电牵引采煤机

该文从控制系统、硬件和软件设计三个方面着手,详细介绍了西安煤矿机械有限公司基于PCC开发的新型采煤机电气控制系统。     

提高PLC控制系统抗干扰的研究

PLC控制技术的应用越来越广泛,但其系统可靠性问题却没有受到应有的重视。该文对影响PLC控制系统可靠性的主要干扰因素进行了较为详尽的分析,从硬件结构和软件编程两方面,研究探讨了提高PLC控制系统可靠性的方法和措施。     

基于GTST-DMLD的装备RMS综合仿真研究

装备的RMS是装备的重要设计参数,是影响战备完好和全寿命周期费用的关键因素.针对现有RMS仿真方法中存在的问题,以GTST-DMLD作为建模工具,建立起装备功能、装备构成、维修保障系统三者之间关系的描述模型,将其作为装备RMS综合仿真模型的重要组成部分,用于描述部件故障对任务执行的影响和故障部件维修对保障资源的需求.从任务成功的角度出发,构造了基于GTST-DMLD的装备RMS综合仿真模型,制定了仿真流程和仿真算法.以舰船推进系统为例,建立起舰船推进系统的GTST-DMLD描述模型并进行了软件设计,通过仿真试验,得到了反映舰船推进系统RMS设计特性的统计值.GTST-DMLD的引入为构造大型复杂装备的RMS综合仿真系统提供了简单易行的方法,对于RMS指标设计的优化有重要的现实意义.     

Efficient structural reliability analysis via a weak-intrusive stochastic finite element method

This paper presents a novel methodology for structural reliability analysis by means of the stochastic finite element method (SFEM). The key issue of structural reliability analysis is to determine the limit state function and corresponding multidimensional integral that are usually related to the structural stochastic displacement and/or its derivative, e.g., the stress and strain. In this paper, a novel weak-intrusive SFEM is first used to calculate structural stochastic displacements of all spatial positions. In this method, the stochastic displacement is decoupled into a combination of a series of deterministic displacements with random variable coefficients. An iterative algorithm is then given to solve the deterministic displacements and the corresponding random variables. Based on the stochastic displacement obtained by the SFEM, the limit state function described by the stochastic displacement (and/or its derivative) and the corresponding multidimensional integral encountered in reliability analysis can be calculated in a straightforward way. Failure probabilities of all spatial positions can be obtained at once since the stochastic displacements of all spatial points have been known by using the proposed SFEM. Furthermore, the proposed method can be applied to high-dimensional stochastic problems without any modification. One of the most challenging problems encountered in high-dimensional reliability analysis, known as the curse of dimensionality, can be circumvented with great success. Three numerical examples, including low- and high-dimensional reliability analysis, are given to demonstrate the good accuracy and the high efficiency of the proposed method.     

Sample regeneration algorithm for structural failure probability function estimation

An efficient strategy to approximate the failure probability function in structural reliability problems is proposed. The failure probability function (FPF) is defined as the failure probability of the structure expressed as a function of the design parameters, which in this study are considered to be distribution parameters of random variables representing uncertain model quantities. The task of determining the FPF is commonly numerically demanding since repeated reliability analyses are required. The proposed strategy is based on the concept of augmented reliability analysis, which only requires a single run of a simulation-based reliability method. This paper introduces a new sample regeneration algorithm that allows to generate the required failure samples of design parameters without any additional evaluation of the structural response. In this way, efficiency is further improved while ensuring high accuracy in the estimation of the FPF. To illustrate the efficiency and effectiveness of the method, case studies involving a turbine disk and an aircraft inner flap are included in this study.     

Hands-free administration of subjective workload scales: Acceptability in a surgical training environment

Introduction

Subjective workload measures are usually administered in a visual-manual format, either electronically or by paper and pencil. However, vocal responses to spoken queries may sometimes be preferable, for example when experimental manipulations require continuous manual responding or when participants have certain sensory/motor impairments. In the present study, we evaluated the acceptability of the hands-free administration of two subjective workload questionnaires - the NASA Task Load Index (NASA-TLX) and the Multiple Resources Questionnaire (MRQ) - in a surgical training environment where manual responding is often constrained.

Method

Sixty-four undergraduates performed fifteen 90-s trials of laparoscopic training tasks (five replications of 3 tasks - cannulation, ring transfer, and rope manipulation). Half of the participants provided workload ratings using a traditional paper-and-pencil version of the NASA-TLX and MRQ; the remainder used a vocal (hands-free) version of the questionnaires. A follow-up experiment extended the evaluation of the hands-free version to actual medical students in a Minimally Invasive Surgery (MIS) training facility.

Results

The NASA-TLX was scored in 2 ways - (1) the traditional procedure using participant-specific weights to combine its 6 subscales, and (2) a simplified procedure - the NASA Raw Task Load Index (NASA-RTLX) - using the unweighted mean of the subscale scores. Comparison of the scores obtained from the hands-free and written administration conditions yielded coefficients of equivalence of r = 0.85 (NASA-TLX) and r = 0.81 (NASA-RTLX). Equivalence estimates for the individual subscales ranged from r = 0.78 (“mental demand”) to r = 0.31 (“effort”). Both administration formats and scoring methods were equally sensitive to task and repetition effects. For the MRQ, the coefficient of equivalence for the hands-free and written versions was r = 0.96 when tested on undergraduates. However, the sensitivity of the hands-free MRQ to task demands (η_partial² = 0.138) was substantially less than that for the written version (η_partial² = 0.252). This potential shortcoming of the hands-free MRQ did not seem to generalize to medical students who showed robust task effects when using the hands-free MRQ (η_partial² = 0.396). A detailed analysis of the MRQ subscales also revealed differences that may be attributable to a “spillover” effect in which participants’ judgments about the demands of completing the questionnaires contaminated their judgments about the primary surgical training tasks.

Conclusion

Vocal versions of the NASA-TLX are acceptable alternatives to standard written formats when researchers wish to obtain global workload estimates. However, care should be used when interpreting the individual subscales if the object is to make comparisons between studies or conditions that use different administration modalities. For the MRQ, the vocal version was less sensitive to experimental manipulations than its written counterpart; however, when medical students rather than undergraduates used the vocal version, the instrument’s sensitivity increased well beyond that obtained with any other combination of administration modality and instrument in this study. Thus, the vocal version of the MRQ may be an acceptable workload assessment technique for selected populations, and it may even be a suitable substitute for the NASA-TLX.     

基于有线和无线设计的大型风电场通信系统

从运行的安全性和可靠性角度考虑,要求大型风电场具有完善的监控系统。在分析了现有风电场监控系统的有线和无线传输方式的优劣性基础上,针对有线介质不可预知的破坏可能和海上风电运行维护不便等问题,提出了一种以太网和地面无线测控网相结合的大型风电场监控通信系统。该系统满足大型风电场传递大量数据的要求,并能解决就地监控与中央监控之间的通信备份;同时还可实现远程监控、中央监控和就地监控之间实时、可靠和安全的通信。     

非线性系统故障诊断与容错控制技术

在分析非线性系统故障诊断与容错控制技术特点的基础上,研究了该技术在国内外的研究进展和主要方法.同时,比较了几种常见故障诊断和容错控制方法的特点.最后总结了非线性系统故障诊断与容错控制领域亟待解决的几个重点和难点问题,并对该研究领域的发展趋势进行了展望.     

差压测漏仪微泄漏的建模与仿真

为研究密封件的微泄漏量大小与检测时间之间的关系,实现检测时间与检测可靠性的优化,通过分析密封件微小泄漏的理论,建立了微小泄漏的等效模型。基于此模型,采用AMESim仿真软件对差压测漏仪检测微小泄漏的动态特征进行仿真分析,得出了被测件微小泄漏时的动态P-T关系曲线。结果表明,此仿真试验能反映出密封件微泄漏时压力与时间的动态关系,为制定最优的检测时间提供了依据。