Importance measures in risk-informed decision making: Ranking, optimisation and configuration control

This paper describes roles, extensions and applications of importance measures of components and configurations for making risk-informed decisions relevant to system operations, maintenance and safety. Basic importance measures and their relationships are described for independent and mutually exclusive events and for groups of events associated with common cause failures. The roles of importances are described mainly in two groups of activities: (a) ranking safety significance of systems, structures, components and human actions for preventive safety assurance activities, and (b) making decisions about permissible permanent and temporary configurations and allowed configuration times for regulation, technical specifications and for on-line risk monitoring. Criticality importance and sums of criticalities turn out to be appropriate measures for ranking and optimization. Several advantages are pointed out and consistent ranking of pipe segments for in-service inspection is provided as an example.Risk increase factor and its generalization risk gain are most appropriately used to assess corrective priorities and acceptability of a situation when components are already failed or when planning to take one or more components out of service for maintenance. Precise definitions are introduced for multi-failure configurations and it is shown how they can be assessed under uncertainties, in particular when common cause failures or success states may be involved. A general weighted average method is compared to other candidate methods in benchmark cases. It is the preferable method for prediction when a momentary configuration is known or only partially known. Potential applications and optimization of allowed outage times are described.The results show how to generalize and apply various importance measures to ranking and optimization and how to manage configurations in uncertain multi-failure situations.     

Inventory-shortage driven optimisation for product configuration variation

Inventory control is a critical problem in manufacturing systems. Inventory shortage significantly affects system productivity, while excessive stocks increase the operation cost. It is difficult to avoid fully inventory shortage under mass customisation manufacturing based on product configuration. In this paper, we propose a new approach for inventory-shortage driven optimisation of dynamic product configuration variation to meet the requirements of product configuration change and find suitable combination of parts by considering cost, lead-time and inventory variation. The multi-objective optimisation model uses a multi-objective genetic algorithm and adds impact cost, lead-time and inventory factors to the normal configuration optimisation model. An industrial case study demonstrates the practicality and effectiveness of the proposed approach. By means of this research, valid solutions for configuration variation are available to the decision makers.     

Solving fixed configuration problems with genetic search

Configuring a design from parts out of catalogs requires searching large numbers of combinations of parts. Optimizing search techniques are not practical for searching for parts in catalogus because the computation time is often excessive. Rule-based approaches suffer from being domain specific and thus are not appropriate for the general solution methods sought for in this work. The research reported in this paper found that a satisficing technique based on genetic search is a feasible alternative. It shows how catalog search can be solved with a genetic-search approach. It was discovered that encoding catalogs without any regard to part features did not reduce the effectiveness of the technique. The performance of genetic search also compares vary favorably with branch and bound.     

机器人宏／微操作系统精密装配作业的研究

介绍了具有力觉功能的机器人微驱动末端操作器与普通工业机器人ＰＵＭＡ５６２组成的机器人宏／微操作系统。该操作系统不仅具备ＰＵＭＡ机器人运动范围大、速度快的优点，而且更具有微操作器工作精度高、频响快的优势。宏／微操作系统在我们开发的轴－孔装配策略的控制下成功地完成了精密装配作业。     

Analysis and optimisation of a mixed fluid cascade (MFC) process

A mixed fluid cascade (MFC) process that comprises three refrigeration cycles has great capacity for large-scale LNG production, which consumes a great amount of energy. Therefore, any performance enhancement of the liquefaction process will significantly reduce the energy consumption. The MFC process is simulated and analysed by use of proprietary software, Aspen HYSYS. The effect of feed gas pressure, LNG storage pressure, water-cooler outlet temperature, different pre-cooling regimes, liquefaction, and sub-cooling refrigerant composition on MFC performance are investigated and presented. The characteristics of its excellent numerical calculation ability and the user-friendly interface of MATLAB™ and powerful thermo-physical property package of Aspen HYSYS are combined. A genetic algorithm is then invoked to optimise the MFC process globally. After optimisation, the unit power consumption can be reduced to 4.655 kW h/kmol, or 4.366 kW h/kmol on condition that the compressor adiabatic efficiency is 80%, or 85%, respectively. Additionally, to improve the process further, with regards its thermodynamic efficiency, configuration optimisation is conducted for the MFC process and several configurations are established. By analysing heat transfer and thermodynamic performances, the configuration entailing a pre-cooling cycle with three pressure levels, liquefaction, and a sub-cooling cycle with one pressure level is identified as the most efficient and thus optimal: its unit power consumption is 4.205 kW h/kmol. Additionally, the mechanism responsible for the weak performance of the suggested liquefaction cycle configuration lies in the unbalanced distribution of cold energy in the liquefaction temperature range.     

Kinematic synthesis with configuration spaces

This paper introduces a new approach to the conceptual design of mechanical systems from qualitative specifications of behavior. The power of the approach stems from the integration of techniques in qualitative physics and constraint programming. We illustrate the approach with an effective kinematic synthesis method that reasons with qualitative representations of configuration spaces using constraint programming.     

On the representation of rigid body rotational dynamics in Hertzian configuration space

In a previous paper by the author, a geometrical procedure was presented for deriving Lagrange’s equations for a rigid body. The rigid body was represented by an abstract particle moving in a 12-dimensional Euclidean space, called Hertzian configuration space, the metric of which is determined by the radius of gyration of the body. The present paper focuses on the representation of the underlying rotational dynamics in Hertzian space.     

大行程高精度宏/微双重驱动机器人系统的研究

研究了具有宏／微双重驱动定位工作台的控制技术。该工作台采用直线电机进行大行程位移驱动,来保证较大的工作行程和较快的响应速度,采用压电陶瓷微位移器完成精密位移驱动,利用光栅尺实现闭环位移反馈,可以实现lOOmm的工作行程,10nm的重复定位精度。     

机器人精密装配实验系统的研究

介绍了由作者研究的仿生型超精密平面驱动器ＢＵＰＡ、机器人微驱动末端操作器ＦＰＷＭ和具有主被动适应功能的主从微操作器ＡＰＭＭ，将它们与普通的工业机器人组成宏／微操作系统，分别成功地完成了机器人自动精密配作业。     

A comparative study of production control mechanisms using simulation-based multi-objective optimisation

There exist many studies conducted to compare the performance of different production control mechanisms (PCMs) in order to determine which one performs the best under different conditions. Nonetheless, most of these studies suffer from the problems that the PCMs are not compared with their optimal parameter settings in a truly multi-objective context. This paper describes how different PCMs can be compared under their optimal settings through generating the Pareto-optimal frontiers, in the form of optimal trade-off curves in the performance space, by applying evolutionary multi-objective optimisation to simulation models. This concept is illustrated with a bi-objective comparative study of the four most popular PCMs in the literature, namely Push, Kanban, CONWIP and DBR, on an unbalanced serial flow line in which both control parameters and buffer capacities are to be optimised. Additionally, it introduces the use of normalised hyper-volume as the quantitative metric and confidence-based significant dominance as the statistical analysis method to verify the differences of the PCMs in the performance space. While the results from this unbalanced flow line cannot be generalised, it indicates clearly that a PCM may be preferable in certain regions of the performance space, but not others, which supports the argument that PCM comparative studies have to be performed within a Pareto-based multi-objective context.     

基于组态软件和PLC的机翼精加工水平测控系统

利用Modbus通信协议及工业控制计算机（IPC）、组态软件、可编程控制器（PLC）、位移传感器设计开发出机翼精加工水平测控系统。该系统实现了自动／手动自由切换控制、数据的集中管理、传感器的校正、故障报警及检测等多方面功能,为精加工的快速、精确、安全运行提供了保证。该系统投入运行后,较好地实现了工艺控制要求,测控过程稳定可靠,具有较高的性价比,是一种较经济的测控系统。     

Identification of the mechanical behaviour of biopolymer composites using multistart optimisation technique

This paper aims at identifying the mechanical behaviour of starch–zein composites as a function of zein content using a novel optimisation technique. Starting from bending experiments, force–deflection response is used to derive adequate mechanical parameters representing the elastic–plastic behaviour of the studied material. For such a purpose, a finite element model is developed accounting for a simple hardening rule, namely isotropic hardening model. A deterministic optimisation strategy is implemented to provide rapid matching between parameters of the constitutive law and the observed behaviour. Results are discussed based on the robustness of the numerical approach and predicted tendencies with regards to the role of zein content.     

兖矿鲁化28000m~3/h空分设备流程和配置的选择

根据生产实际确定气体产品的技术参数,并结合国内外空分技术水平,选择新建设的28000m3/h空分设备的流程,详细介绍了精馏塔系统和换热器系统等静止设备和空压机、液体泵等运转设备的选型经验。     

20CrMnTi钢位错密度的测定及其位错形态研究

为了探讨20CrMnTi钢的冷变形强化过程位错密度的分布与位错形态,采用X射线衍射法及多晶单线付氏分析理论,在实验基础上测量了不同应变量冷变形时20CrMnTi钢的位错密度,分析了应变量与位错密度及加工硬化的关系,利用透射电子显微镜对冷镦粗件的位错形态进行了观察.结果表明,位错密度随变形量的增加而提高,同时,随变形量增加加工硬化效果增强,晶体位错形态为"曲折"形位错线,应变量较大时位错呈胞状结构.     

A state-space dynamical representation for multibody mechanical systems part I: Systems with tree configuration

Summary This paper deals with the problem of transient wave propagation in isotropic inhomogeneous elastic Cosserat plates of uniform thickness by the method of singular wave curves. The transport equations governing the growth-decay behaviour of all extensional and bending wave modes are explicitly integrated to provide a common general formula involving the material parameters and wave geometry. An example of wave propagation, due to an initially straight wave in a plate with prescribed variable density is worked out in detail.     

基于工控组态软件MCGS的某罐区监控系统的设计与应用

文章介绍了全中文工控组态软件MCGS，并以某罐区监控系统为例，阐述了该系统的组成、功能及采用MCGS开发的人机接口可视化界面(HMI)。系统具有界面友好、易于操作、运行可靠、便于升级扩充等特点。     

天钢28000m~3/h内压缩流程空分设备配置及工艺特点

简介了天津钢铁有限公司两套28000m3/h内压缩流程空分设备的技术参数和流程,详细介绍了主要设备的配置,分析了两套空分设备具有的液体产量高、能耗低和运行安全、可靠等工艺特点。     

A MEMS toolkit for metal-oxide-based gas sensing systems

Silicon micromachining technologies have been used to develop metal oxide gas sensor elements with very small heating power consumption. With the power consumption of a single micromachined sensor element being an order of magnitude less than that of commercial thick-film devices, novel kinds of gas sensing systems become feasible, which allow higher selectivity, lower drift and built-in self-test functionalities to be realised within the power budget of a single thick-film gas-sensing element. Such systems can be built up using components from an emerging MEMS toolkit for miniaturised gas sensing systems. The article presents components of this toolkit and points out system functionalities that can be achieved by combining elements from this kit.