基于Petri网原油处理短期生产计划可调度性分析

由于原油运作短期调度的复杂性,现有的建模过程会忽略一些关键约束,导致不可行解。为了避免这个问题,从控制理论的角度研究短期调度问题,将短期调度中的一个运作决策作为一个控制。基于这个观点,对厂区油罐的数量以及它们的容量、厂区油罐中不同类型原油的库存、管道的运输速率存在的情况,利用Petri网分析其可行性。最后,利用一个实例对短期调度的可行性条件进行验证。     

膜分离技术在原油破乳和含油污水处理中的应用

本文介绍了一种破乳功能膜用于原油破乳脱水和含油污水处理的系统。该系统采用全物理方法，能安装在生产线上，对原油直接脱水分离，将高含水原油变为低含水原油，或使原油含水率达到成品油集输的标准，脱出的污水水质达到油田回注标准。该系统在原油凝固点以上５～１０℃就可运行，在满负荷运行条件下压降＜０．１ＭＰａ，具有较好的分离效果，节省能源，较大幅度降低生产成本     

煤矿辅助运输调度系统的层次颜色Petri网建模

为实现煤矿井下无轨运输车辆的安全调度,提出一种新型调度策略,以此为框架,利用层次颜色Petri网对调度系统进行建模。通过研究模型的运行过程,对调度策略的安全性、正确性及可重用性进行证明。同时,利用模型的状态空间报告对调度系统基本性能作简单分析。结果表明,该调度系统模型可对车辆运输量、区段使用频度及其时间分布以及车辆运输速度与运输任务产生速度的匹配程度进行分析,在应用过程中可以有效提高车辆运输安全性,避免运输事故,辅助管理者规划运输任务,提高矿井辅助运输效率。     

跨入新世纪对我国炼油工业发展的思考

我国炼油工业经过50年的发展已具备一定基础,1999年底原油加工能力已达250Mt,居世界第四位。跨世纪进一步发展,首先要解决好国内外两种原油资源的统筹利用,特别是进口原油所涉及的加工、储备、运输及资源安全等一系列问题。同时要从降低原油成本、提高开工负荷率、降低能耗物耗、延长开工周期、降低加工费用、提高产品质量、满足环保要求等方面全面提高与进口石油产品的竞争能力,应对加入WTO的挑战。     

基于神经网络的复杂系统杂交建模研究

利用先验知识和神经网络黑箱建模相结合,对一类复杂滞后非线性系统进行了杂交建模研究.先验知识建模确定滞后系统模型的形式及主体部分,神经网络估计滞后系统恢复力的未确定部分,所建模型不仅能够进行系统响应预测分析,而且能够获得系统的主体结构特征,对结构设计修改具有指导作用.     

约束求解组件与CAD平台的集成

提出一种几何约束求解组件与CAD平台的集成框架,基于此设计了一个动态几何约束系统.该系统利用目标捕捉和尺寸推断结果,可自动建立优化的欠约束几何约束模型.引入了自定义的约束实体,使得约束关系成为可见的、易管理的对象.增加了的对象反应器和命令反应器,很好地支持了平台本身的Undo/Redo操作.系统实现了约束信息与几何模型文件的同步存取.     

基于UG参数化设计系统的研究

论文是以功率超声珩磨装置的参数化建模为例,在一般零件参数化设计的基础上,提出了一种基于草图装配和草图约束的参数化设计方法。此方法是利用UG建模里的草图功能,在对零件模型进行几何约束和尺寸约束的基础上,用函数表达式建立多个零部件的变量尺寸与装配草图的关系,通过对装配草图里设计变量尺寸的管理,实现整个装置零部件之间的联动。     

光电干扰系统基于UML的C3I系统软件建模

将C^3I系统实时获取信息、传输信息、处理信息进行态势分析与估计,然后自动决策应用于光电干扰系统软件设计,能大幅度提高光电干扰系统的效能,从而提高战区C^3I系统的攻击与防卫效能。首先描述光电干扰系统的功能需求,利用C^4ISR与UML体系结构的高层处理过程提出UML建模的框架;接着应用UML遵循RUP的核心思想和基本原则对光电干扰系统软件进行了建模,逐步进行了需求收集、系统分析与系统设计,在每个过程均用一系列UML图来形象化地表示;最后提出了在建模过程中应注意的问题。利用已成为事实上标准并且符合人们思维习惯的UML进行系统建模,开发周期相对短,产品较丰富并且保证了系统开发和维护人员对系统的理解,系统分析、系统设计以及系统维护的一致性,更重要的是模型建立后可直接编程实现。     

计算机模拟建模

通过在数学建模教学实践中编写的两个典型案例的建模和利用MATLAB软件求解，具体展示了对连续系统计算机模拟的建模步骤和方法。     

履带行走机构自动化装配方法与系统实现

针对履带行走机构的自动化装配问题,以某型无负重轮式履带行走机构为对象,研究了自动化装配中的姿态定位和约束添加的关键问题.提出一种采用辅助草图和参考面进行姿态定位和约束添加的履带行走机构自动化装配的方法,开发了履带行走机构自动化装配系统.该方法能够大大提高装备样机设计建模的效率,将设计人员从繁琐的建模与装配工作中解脱出来．     

混合供油模式下炼油短期生产计划的可调度性分析

炼油生产中,在许多情况下,供油罐的数量不足以使用一个油罐供应一个分馏塔的炼油模式,而需要使用一个油罐供一个分馏塔和一个油罐供两个分馏塔的混合模式。这使得炼油短期生产计划更为复杂。本文从控制理论的角度研究这种混合供油模式下的炼油短期调度问题。通过建立系统的Petri网模型,分析了在混合模式下供油罐的数量和容量、分馏塔数量、管道输油速率对系统可调度性的影响,推导出了可调度的条件。并用一个生产实例对得到的可调度性条件进行了验证.     

基于TOC和Petri网的业务流程重组方法

业务流程重组是企业根据市场和环境变化进行自身调整和完善,从而在竞争中取得优势的重要手段.通过Petri网建模可以对企业业务流程进行动态分析和控制,寻找制约企业盈利的最薄弱环节.在此基础上,应用约束理论(TOC)能够对业务流程中最薄弱的环节进行改进和重组,逐一消除制约环节,不断提升企业的竞争能力.在分析Petri网流程建模思路和约束理论基本原理的基础上,提出了基于Petri网和约束理论的业务流程重组方法,并进行了实证研究.     

Petri net based scheduling

Timed Petri nets can be used to model and analyse scheduling problems. To support the modelling of scheduling problems, we provide a method to map tasks, resources and constraints onto a timed Petri net. By mapping scheduling problems onto Petri nets, we are able to use standard Petri net theory. In this paper we will show that we can use Petri net based tools and techniques to find conflicting and redundant precedences, upper- and lower-bounds for the makespan, etc. This is illustrated by a Petri net based analysis of the notorious 10×10 problem due to Fisher & Thompson (1963)     

Assembly/disassembly task planning and simulation using expert Petri nets

Automatic assembly/disassembly planning is recognized as an important tool for reducing the manufacturing costs in concurrent product and process development. This paper developed a knowledge-based expert Petri net model by incorporating expert system techniques in artificial intelligence into ordinary Petri nets for an analytical framework of understanding, representing and reasoning the assembly/disassembly tasks. Substantial extensions have been made to ordinary Petri nets by adding control places, time constraints, and place and transition knowledge annotations. The proposed expert Petri net model can be considered as the hybrid of expert systems and ordinary Petri nets. Through these extensions, the capacities of modelling and representation of ordinary Petri net models are largely enhanced, and thus the expert Petri net models are more powerful than ordinary Petri nets. Such intelligent Petri net models can combine the abilities of modelling, planning, and performance evaluation for assembly/disassembly tasks in an integrated and intuitive way, and can therefore be applied to either linear/non-linear, static/dynamic, or on-line/off-line assembly/disassembly tasks at both high and low levels. The developed assembly/disassembly planning system can generate the best strategies and plans for assembly/disassembly. The research findings are exemplified with a real assembly to show the effectiveness of the method.     

基于增强高级Petri网的规则系统一致性问题检查

针对含有变量和非事件的规则系统,提出了基于增强高级Ｐｅｔｒｉ网的ＲＢＳ建模,并应用着色方法对上述规则系统进行知识一致性检查,提出的含变量的规则表示可以是一种多种知识表示形式之间的转换模型,因此,对其进行Ｐｅｔｒｉ网建模和一致性分析具有实际意义。     

基于eM-Plant求解具有晶圆重入过程的单臂组合设备最优调度的仿真方法

在半导体组合设备的晶圆加工过程中,常常要求晶圆重入,原子层沉积加工(ALD)就是典型的晶圆加工过程。对这样的系统实施调度是一个挑战性的问题。研究单臂组合设备的调度问题,目的在于求解ALD重入过程的最优调度。建立了系统的Petri网模型,利用该模型,可以通过比较非常有限的若干调度的生产节拍而得到其重入过程的最优调度。基于所建立的Petri网模型,开发出了基于eM-Plant的仿真系统,可以有效地获得给定调度的生产节拍。给定系统的参数可以有效地求得重入过程的最优调度。文中应用例子来说明所提出的方法的应用。     

Modelling and planning of the disassembly processes using an enhanced expert Petri net

A sound disassembly Petri net model for the effective planning of disassembly processes and tasks is outlined. Owing to the unmanageable complexity associated with modelling of the disassembly processes and tasks, it becomes essential to have a more powerful Petri net model developed by incorporating the concepts of expert system, knowledge representation techniques, etc. Disassembly task planning at high and low levels can easily be represented by proposed high- and low-level expert Petri net. An algorithmic approach is also suggested for evaluating the end-of-life values of a product. These values are used to determine an optimal disassembly sequence and it is incorporated in the expert disassembly Petri net. A proposed expert enhanced high-level coloured disassembly Petri net is empowered to express such details vividly. The application of the proposed expert enhanced high-level coloured disassembly Petri net model is demonstrated through the sample disassembly of a flashlight.     

Petri-net based applications for supply chain management: an overview

Supply networks are discrete event dynamic systems consisting of suppliers, manufacturers, distributors, and customers. It is a difficult and challenging task to model such a complex system. Recently, characterised as being capable of model parallelism and synchronisation, Petri nets (PNs) have attracted great attention for modelling and studying a supply network. Since each type of Petri net has its unique properties to model specific applications, this paper reviews and classifies Petri net applications for supply chain management (SCM). According to the decision problems facing SCM, we have the Petri net applications classified into three areas: competitive strategy, firm focused tactics, and operational efficiency. Categorising the Petri net applications will provide a guideline to industry practitioners and research academics to choose the appropriate Petri net for the problem. In addition, the paper attempts to offer future directions in applying the Petri net to SCM including: (1) modelling with uncertainty elements; (2) addressing the scalability issue of Petri nets; (3) integrating Petri nets with other tools; and (4) extending Petri nets to emerging applications.