基于Simulink的混合试验系统及其验证

作为混合模拟的工具,目前的混合试验系统向分布式复杂化发展,这不便初学者理解混合模拟的执行过程,也分散了研究者集中研究的精力,为此本文研究了基本的混合试验系统。首先介绍了Matlab中的Simulink仿真环境,然后提出了基于Simulink的混合试验系统,并讨论了混合模拟执行中的关键问题。最后分别利用简化的加载系统模型和真实的加载系统进行了混合试验系统仿真与验证。仿真结果表明所提混合试验系统各模块可协同工作;试验结果表明该混合试验系统便于进行硬件在回路仿真。     

A bounded-search iterated greedy algorithm for the distributed permutation flowshop scheduling problem

As the interest of practitioners and researchers in scheduling in a multi-factory environment is growing, there is an increasing need to provide efficient algorithms for this type of decision problems, characterised by simultaneously addressing the assignment of jobs to different factories/workshops and their subsequent scheduling. Here we address the so-called distributed permutation flowshop scheduling problem, in which a set of jobs has to be scheduled over a number of identical factories, each one with its machines arranged as a flowshop. Several heuristics have been designed for this problem, although there is no direct comparison among them. In this paper, we propose a new heuristic which exploits the specific structure of the problem. The computational experience carried out on a well-known testbed shows that the proposed heuristic outperforms existing state-of-the-art heuristics, being able to obtain better upper bounds for more than one quarter of the problems in the testbed.     

基于模具-制件相互作用的复合材料制件固化变形数值模型

针对复合材料制件在成型过程中的固化变形这一关键技术问题,通过在模具与复合材料制件之间引入剪切层的方法,建立了预测复合材料制件固化变形的解析计算模型和有限元仿真模型。剪切层的剪切模量用来衡量固化过程中模具与复合材料制件之间的相互作用,其数值大小通过与实验数据进行比对而得到。基于建立的固化变形模型,与文献中已有的实验结果进行了比较。结果表明:所建立的模型具有较高的可靠性。同时针对L型复合材料制件建立了三维有限元仿真模型,模型中除考虑材料各向异性和化学收缩效应以外,还将成型过程中模具与复合材料制件间的相互作用考虑在内。模拟结果表明:引入模具作用后L型零件的固化变形预测结果更加准确。      

Spatial arrangement using deep reinforcement learning to minimise rearrangement in ship block stockyards

As the shipbuilding industry is an engineering-to-order industry, different types of products are manufactured according to customer requests, and each product goes through different processes and workshops. During the shipbuilding process, if the product is not able to go directly to the subsequent process due to physical constraints of workshop, it temporarily waits in a stockyard. Since the waiting process involves unpredictable circumstances, plans regarding time and space cannot be established in advance. Therefore, unnecessary movement often occurs when ship blocks enter or depart from the stockyard. In this study, a reinforcement learning approach was proposed to minimise rearrangement in such circumstances. For this purpose, an environment in which blocks are arranged and rearranged was defined. Rewards based on the simplified rules were logically defined, and simulation was performed for quantitative evaluation using the proposed reinforcement learning algorithm. This algorithm was verified using an example model derived from actual data from a shipyard. The method proposed in this study can be used not only to the arrangement problem of ship block stockyards but also to the various arrangement and allocation problems or logistics problems in the manufacturing industry.     

Distributed supply chain network modelling and simulation: integration of agent-based distributed simulation and improved SCOR model

Agent-based distributed simulation is an efficient methodology for modelling and analysing such complex adaptive systems as dynamic supply chain networks. However, it lacks an acceptable generic standard. Supply chain operations reference (SCOR) model is a cross-functional framework widely accepted as an industry standard. It provides the standard processes, performance metrics, best practices and associated software functionalities for modelling, evaluating and improving supply chain networks. However, it is a static tool. Integration of agent-based distributed simulation and SCOR model can exploit their advantages to form a generic methodology for modelling and simulation of a wide range of supply chain networks. Therefore, this paper proposes a methodology for distributed supply chain network modelling and simulation by means of integration of agent-based distributed simulation and an improved SCOR model. The methodology contains two components: a hierarchical framework for modelling supply chain network based on the improved SCOR model and agent building blocks integrating the standard processes from the SCOR model. The hierarchical framework provides an approach for structure modelling in any level with different granularities based on the improved SCOR model, and allows rapidly mapping a supply chain network into the structure model of a multi-agent system; while agent building blocks are quite useful and convenient to fill the structure model to fulfil its function modelling. With the approach of structure modelling and function filling, not only can the process of agent-based supply chain network modelling be accelerated, but also the built models can be reused and expanded. Because the hierarchical framework is based on the conceptual framework of SCOR model and agent building blocks integrate the standard processes from SCOR model, the proposed methodology is more generic. In addition, the issues of sub-model synchronisation and data distribution management in the agent-based distributed simulation implementation are taken into consideration and the corresponding solutions for these issues are proposed. Finally, an example of a supply chain network is modelled and implemented to illustrate the proposed methodology and related solutions.     

无网格方法数值结果的可视化方法与实现

科学计算可视化是科学计算中不可缺少的一个组成部分,其主要任务是将数值模拟产生的大量复杂的数据信息通过计算机技术转换成图形、图像信息。无网格方法是一种基于点的数值计算方法,各离散点之间没有联结信息,其数值结果的可视化后处理是一件很困难的事情,尤其当离散点随机分布时,更是如此。Delaunay 三角化是十分理想的散乱数据的可视化工具,它可以根据一组随机分布的离散点数据生成唯一的近似等边三角形。首先介绍了 Voronoi 图与 Delaunay 三角化的基本原理,然后介绍了实现 Delaunay 三角剖分的算法及无网格方法数值结果可视化的实现方法,最后给出了无网格方法可视化的若干应用实例。     

基于虚拟仿真与TRIZ的产品人机工程问题解决方法研究

为了快速准确地解决产品的人机工程问题,提升产品的人机性能,提出了一种基于虚拟仿真与TRIZ （Teoriya Resheniya Izobreatatelskikh Zadatch,发明问题解决理论）的人机工程问题解决方法。首先,利用虚拟仿真工具对产品的人机性能进行评估,根据所得的人体数据进行产品区域关联,确定存在人机工程问题的产品区域,并利用功能模型和因果分析找到产生人机工程问题的根原因。然后,根据产品人机工程设计案例及专家问卷调查结果,构建TRIZ标准工程参数与人机工程设计准则关联表,并通过该关联表和TRIZ冲突分析工具获取可解决产品人机工程问题的设计方案;基于理想度概念,提出产品人机性能理想度评估方法,并对得到的设计方案进行评价,从而确定最佳设计方案。将提出的方法应用于电动曲线锯人机工程问题解决实例,既快速解决了问题,又提升了电动曲线锯的易用性。结果表明,所提出的方法能够提高产品创新设计效率及其人机性能,可为产品人机工程问题的解决提供一种新思路。     

Research on solving method of product ergonomics problem based on virtual simulation and TRIZ

In order to quickly and accurately solve the ergonomics problems and improve the human-machine performance of products, a solving method of product ergonomics problem based on the virtual simulation and TRIZ (Teoriya Resheniya Izobreatatelskikh Zadatch) is proposed. Firstly, the evaluation of human-machine performance for the product was carried out by the virtual simulation tool, and the product area correlation was performed based on the obtained human body data to determine product areas with ergonomics problems. The root causes of product ergonomics problems were found by using the functional model and causal analysis. Then, according to the product ergonomics design cases and expert questionnaire survey results, a correlation table of TRIZ standard engineering parameters and ergonomics design criteria was constructed, and design schemes that could solve the product ergonomics problems were obtained through the correlation table and conflict analysis tool of TRIZ; based on the concept of ideality, the ideality evaluation method of product human-machine performance was proposed and the evaluation for obtained design schemes was carried out to determine the best design scheme. The proposed method was applied to solve the ergonomics problem of electric jig saw, which not only solved the problem quickly,but also improved the usability of electric jig saw. The results show that the proposed method can improve the innovation design efficiency and the ergonomics performamce of products, which provides a new idea for solving product ergonomics problems.     

基于MLS-NMM的摩擦接触问题研究

摩擦接触问题的求解是将基于移动最小二乘插值的数值流形法（MLS-NMM）应用到裂纹扩展的必经之路。该文通过结合罚-线性互补方式的施加接触边界条件,并使用拉格朗日乘子法施加本质边界条件,得出一套基于MLS_NMM的摩擦接触问题的求解体系。该方法无需节点与边界重合,则可域外布点和均匀布点,来提高插值精度和降低布点难度,尤其是接触边界处。采用罚-线性互补的方式施加接触条件,使计算格式统一而简洁,利于编程实现。通过算例表明,该方法能准确地模拟接触面的张开、黏结和滑动状态,证明该方法对求解接触摩擦问题是可行的、有效的。     

A desired load distribution model for scheduling of unrelated parallel machines

Scheduling problems concern the allocation of limited resources over time among both parallel and sequential activities. Load balancing has been adopted as an optimization criterion for several scheduling problems. However, in many practical situations, a load-balanced solution may not be feasible or attainable. To deal with this limitation, this paper presents a generic mathematical model of load distribution for resource allocation, called desired load distribution (DLD). The objective is to develop a DLD model for scheduling of unrelated parallel machines that can be used both in centralized resource management settings and in agent-based distributed scheduling systems. The paper describes the proposed DLD model in details, presents a dynamic programming based optimization algorithm for the proposed model, and then discusses its application to agent-based distributed scheduling.     

The Application of Program Generator Software and Its Extensions to Discrete Event Simulation Modeling

The paper is a tutorial review of program generators applied to simulation model building. A program generator is a tool to aid in the production of computer-coded representations of a logical model. A simple model introduces one generator, DRAFT. The application of the tool to a large engineering project is then used to highlight practical advantages and problems. The implications of the underlying network structure are considered. The presentation of development work illustrates the extent to which such modeling software can be extended. These extensions will support the model users in all aspects of decison making.     

复合材料Ⅴ型构件的固化变形预测及其工装型面设计

利用固化动力学模型对20 mm厚度和3mm厚度的ZT7H/5429碳纤维复合材料层合板进行了固化模拟,在固化过程中,20 mm厚度平板出现了温度峰值,中心温度与表面温度差不超过6℃,3mm平板温度分布均匀,温度历程与热压罐工艺温度基本一致.利用简化的温度场和等效热膨胀系数对609和90°拐角的Ⅴ型基准试件进行了固化变形模拟,并进行了Ⅴ型基准试件的固化试验.60°和90°拐角试件的固化回弹角的模拟值分别为1.58°和1.18°,试验测得的回弹角的平均值分别为1.59°和1.11°.对Ⅴ型复合材料蒙皮构件进行了固化变形模拟,并得到了补偿过的工装型面,在该工装上成型的试件与设计形状基本一致.     

NUMERICAL SOLUTIONS OF LINEAR MIXED BOUNDARY VALUE PROBLEMS USING STOCHASTIC REPRESENTATIONS

The application of Itô's formula induces some probabilistic representations of solutions of deterministic linear problems with boundary conditions of Dirichlet, Neumann, Fourier and mixed types. These representations are used to establish some easily implementable algorithms which compute an approximate solution by means of simulation of reflected random walks. They do not require selected configurations at the neighbourhood of the domain boundary, nor a discretization mesh. The associated simulation methods are obtained and applied to problems for each class of boundary conditions. Numerical experiments with distributed source in two- or three-dimensional geometries, and computational results with estimation of error, are reported. © 1997 by John Wiley & Sons, Ltd.     

Modular Petri nets for simulation of flexible production systems

The use of Petri nets for modelling, analysing and simulating complex distributed production systems meets serious problems when the size of the model grows. Therefore, it would be very useful to decompose a Petri net based model into smaller models linked with one another. The aim of this paper is to suggest and discuss some possible definitions of Modular Petri nets. This is accomplished by introducing the concept of Petri subnet. Two possible definitions are proposed and the meaning and the usefulness with respect to both model definition and model executability for simulation are pointed out. All definitions are given for the basic model of Petri nets. The extension of modularity concepts to high level Petri nets is shown to be possible in the second part of the paper, where an application is illustrated. In particular an algorithm is given which allows automatic composition of subnets into a larger model     

动态仿真在车身覆盖件成形中的应用

阐述了动态仿真在车身覆盖件成形领域实用化的三个关键要素：成功案例的数字化,高效的优化算法,新型的等效拉深筋阻力模型,给出了动态仿真在成形性评价,汽车板选材,拉深筋优化设计方面的应用实例,以期有助于汽车界更好地动态仿真这个先进的CAE分析工具。     

欠采样噪声分析与光电一体化设计

欠采样噪声产生分布于整个画面的附加像,给目标识别等应用带来困难。基于信息理论,建立了欠采样噪声的应用分析模型,提出了采样成像系统光电一体化设计方法。通过仿真试验,得出欠采样噪声与光学成像系统参数的关系。理论分析和仿真证明,根据系统互信息量选择光、电系统参数,可以减小欠采样噪声,提高图像质量。     

Bootstrapping Analysis of Lifetime Data with Subsampling

Because of cost and time limitations, reliability experiments frequently contain subsampling, which is a restriction on randomization. A two‐stage approach can analyze right censored Weibull distributed reliability data with subsampling. However, in implementing such a method, we found that it did not address the problems of how to perform confidence intervals of low percentiles and reduce the bias of estimates. In this paper, we present a two‐stage bootstrapping approach and an unbiasing factor approach to solve the aforementioned problems. An example is provided to illustrate the proposed method. In addition, the proposed method is compared with existing methods through simulation. The resulting simulations show that the proposed method performs well in low percentiles. Copyright © 2015 John Wiley & Sons, Ltd.     

A hybrid approach to machine-tool selection through AHP and simulation

The selection process of a machine tool has been a critical issue for companies for years, because the improper selection of a machine tool might cause many problems having a negative effect on productivity, precision, flexibility, and a company's responsive manufacturing capabilities. Therefore, in this paper, to determine the best machine tool satisfying the needs and expectations of a manufacturing organization among a set of possible alternatives in the market, a hybrid approach is proposed, which integrates an analytic hierarchy process (AHP) with simulation techniques. The AHP as one of the most commonly used multiple criteria decision-making methods is used to narrow down all possible machine tool alternatives in the market by eliminating those whose scores (or weights) are smaller than a determined value obtained under certain circumstances. Then, a simulation generator is used first to automatically model a manufacturing organization, where the ultimate machine tool will be used, and second to try each alternative remaining from the AHP as a scenario on the generated model. Finally, the final alternative is selected by using the unit investment cost ratio, which is calculated by dividing the investment cost per year of each alternative by the additional number of produced units obtained from the simulation experiment of the relevant alternative.     

Lattice Boltzmann simulations of binary fluid flow through porous media

The lattice Boltzmann equation is often advocated as a simulation tool that is particularly effective for complex fluids such as multiphase and multicomponent flows through porous media. We construct a three-dimensional 19 velocity lattice Boltzmann model for immiscible binary fluids with variable viscosities and density ratio based on the model proposed by Gunstensen. The model is tested for the following binary fluid flow problems: a stationary planar interface among two fluids; channel flow of immiscible binary fluids; the Laplace problem; and a rising bubble. The results agree well with semi-analytic results in a range of the E?tv?s, Morton and Reynolds number. We also present preliminary simulation results for two large-scale realistic applications: the flow of an air-water mixture in a waste-water batch reactor and the saturation hysteresis effect in soil flow. We discuss some limitations of the lattice Boltzmann method in the simulation of realistic and difficult multiphase problems.     

工业制造车间离散计量设备的数据感知与可视化系统

为解决工业制造车间存在的计量设备分布离散、计量数据难以统一采集、计量数据利用率低、设 备后期维护成本高等问题,建立工业制造车间离散计量设备的数据感知与可视化系统。通过搭建数据转换协议 仓,实现多种类型、多种品牌计量设备的多协议通讯兼容,解决设备离散分布时,数据的统一采集和集中管理 难题。数据转换协议仓集成在客户端软件中,具有成本低、易部署、协议拓展方便等优点。系统结合数据分析 和可视化技术,实时感知车间计量设备数据变化,为管理者直观、清晰地展示数据及分析结果。该系统实现了 计量数据的实时采集和分析处理,提高了数据利用效率,为生产决策提供了重要保障。系统的可视化分析功能 能够帮助管理者快速了解车间计量设备工作状况,提升了车间计量设备的整体运行效率。