基于ESHL EP-N 的产品开发过程建模、 调度与仿真

为获得可行的产品开发计划,用扩展随机高级判断Ptri网建立产品开发过程的模型,并给出产品开发过程的仿真方法。仿真流程的输入是由数学方法获得的初始产品开发计划,仿真过程中使用4类规则来调度产品设计活动。根据仿真结果考察初始计划的可行性,并获得实际的产品开发计划。仿真结果表明,该调度规则和仿流程是有效而可行的。     

基于扩展随机高级判断Petri网的FMS调度和仿真

本文提出一种新的更适合FMS调度仿真的扩展随机高级E-net,简称ESHLEP-N(Extended stochastic High Level Evluation Petri Net)。以ESHLEP-N模型为基础,设计并建立了FMS调度仿真专家系统。借助于该系统提出并研究了新的旨在减少空闲(no-inputs)和阻塞的实时动态再调度规则。经过仿真,证明新规则的产率(throughput)比传统规则平均提高6.48％。本文的部分成果已经用于航空航天部159厂的高级DNC系统的设计之中。     

基于虚拟样机的复杂产品协同设计与仿真关键技术研究

主要研究并行工程环境下复杂产品虚拟样机协同设计与仿真的体系结构及其关键技术。提出虚拟样机协同设计与仿真系统的体系结构与整体解决方案，研究面向虚拟样机的数字化多领域集成建模理论与方法，建立面向虚拟样机开发全生命周期的集成过程管理与冲突协调模型，提出面向复杂产品虚拟样机开发的多学科协同设计、协同仿真和智能决策支持的理论与方法，建立复杂产品虚拟样机协同支持环境，有效提高企业创新能力和核心竞争力。     

Conceptual frame for development of optimized simulation-based scheduling systems

The detailed system architecture of the optimized simulation-based scheduling system (OSBSS) is presented to generate an optimized scheduling. In OSBSS environment, a simulation optimizer interactively communicates with a simulation model to improve the current scheduling with respect to the performance criteria. The performance of a simulation engine is very important issue in developing OSBSS since it is necessary to simulate multiple alternatives until given criteria are satisfied. The integration of the discrete event simulation with a rule-based system is suggested to effectively handle condition-based events within a rule-based environment. The capability to change the dispatching rules during simulation is also desirable to reduce OSBSS development efforts. Database-driven simulation model generation concept is presented to effectively generate and maintain the simulation model with updated domain data. The generic development procedures for OSBSS, using IDEF modeling methods, are presented, which may serve as a template for actual development.     

Modeling and performance analysis of product development process network

Product development process (PDP) is a complex system, in which design activities and design resources are connected to each other according to specific rules. Considering the elements of PDP (complex forms of design activities, interdisciplinary collaboration and multiform resources) and relationships between them, a product development process network (PDPN) is proposed and its performance is further analyzed and optimized. In order to establish the PDPN, design activities and resources used in the PDP are mapped into the nodes of the network. And the relationships among the nodes are mapped into the edges. Then, a level-based evaluation model is proposed to illustrate the forming procedure of establishing the PDPN. Then, some typical topological and physical characteristics of the PDPN are defined and analyzed based on the complex network theory. In order to balance the resource load, the PDPN is divided into different communities, wherein a Girvan–Newman (GN) algorithm together with improved measure criterion is applied. Finally, the design process of a steam turbine rotor is chosen as an example to illustrate the feasibility and availability of the proposed method.     

A simulation model for eliciting scheduling knowledge: an application to the precast manufacturing process

This paper discusses the process of eliciting scheduling knowledge from a simulation model and the development of a dynamic modelling approach to the scheduling process in the precast concrete industry. Due to the problems associated with eliciting scheduling knowledge from an ‘expert’ in the precast industry or perhaps in most of the manufacturing industries, simulation is used to complement human knowledge in this paper. Such knowledge will be used for online support to advise production schedulers and for further development of the simulation model by incorporating the knowledge in the model and making it more dynamic. The paper suggests that dynamic selection of scheduling rules during real-time operation has been recognised as a promising approach to the scheduling process in the precast industry. For this strategy to work effectively, sufficient knowledge is required to enable the model to predict the most effective scheduling rule to meet current factory status. The paper concludes that if the knowledge rules are used effectively, they could be a considerable managerial tool for exploring and improving managerial practices. Recommendations have been made regarding the development of a more realistic and practical scheduling system.     

基于虚拟样机的复杂产品协同设计与仿真关键技术研究*

主要研究并行工程环境下复杂产品虚拟样机协同设计与仿真的体系结构及其关键技术。提出虚拟样机协同设计与仿真系统的体系结构与整体解决方案,研究面向虚拟样机的数字化多领域集成建模理论与方法,建立面向虚拟样机开发全生命周期的集成过程管理与冲突协调模型,提出面向复杂产品虚拟样机开发的多学科协同设计、协同仿真和智能决策支持的理论与方法,建立复杂产品虚拟样机协同支持环境,有效提高企业创新能力和核心竞争力。     

复杂圆柱壳结构参数化建模方法及模型库设计

针对船舶的主要结构形式——复杂圆柱壳结构,为研究其快速建模方法以实现船舶结构的优化设计,基于隐式参数化模型概念提出参数化模型表征方法,建立其分类和命名体系,给出其参数化建模方式和流程,利用数值仿真工具完成其参数化模型库设计和开发,并应用于某船舶结构的快速建模.算例表明:复杂圆柱壳参数化模型库设计合理,满足复杂圆柱壳结构快速建模和修改的要求.     

Computing Completion Time and Optimal Scheduling of Design Activities in Concurrent Product Development Process

This paper proposes a time-computing model and a scheduling method for shortening the completion time of product development under the given rework cost budget. As overlapping and iteration exist between or among design activities in concurrent product development, predictability and efficiency of the process deserve attention. By using the corresponding design structure matrix, the characteristics of information flow are obtained and applied to analysis of the dynamic behavior of the product development process. A time-computing model is set up to estimate the rework cost and completion time of each of the activities, between which both iteration and overlapping are observed. Through sequential quadratic programming, an optimization algorithm is developed for minimizing the development completion time under the constraint of the given rework cost budget. Our application results acquired from our experiments have verified the feasibility and validity of the approach.     

网络数据动态传输与存储安全自动监测系统设计

为了提高网络数据动态传输与存储安全自动监测能力,进行监测系统优化设计,提出基于负载均衡调度和嵌入式总线传输控制的网络数据动态传输与存储安全自动监测系统设计方法。构建网络数据动态传输的信道均衡调度模型,采用随机线性均衡控制方法进行网络数据动态传输与存储过程中的信道自适应调度,提取网络数据动态传输过程中的模糊关联规则,采用自适应的链路转发控制方法进行网络数据动态传输与存储的安全监测和负载均衡调度。在嵌入式总线协议下进行网络数据动态传输与存储安全自动监测系统的软件开发设计。仿真结果表明,采用该方法进行网络数据动态传输与存储安全自动监测的稳定性较好,自适应控制能力较强,降低了网络数据动态传输的误比特率。     

A process simulation based method for scheduling product design change propagation

It is expected by enterprises that design changes that occur in a complex product development process can be resolved in a cost-effective way so that products modified for new customer requirements or new technology can be launched into the market without increasing much cost and time. Usually there are different solutions or methods for design changes, which may have different impacts on the whole process. Since a complex product development process consists of many design tasks and different relationships among these tasks, it is not easy to analytically compute the completion time when change propagation finishes. In this paper a process simulation based method is proposed to select the most economic propagation path for each design change, which can reduce the total process time for changes occurring in the complex product development process. “And/Or” graph nodes are used to represent the input and output logics of each task in the design process. Mathematic models are developed to calculate the completion time of the change propagation process. Monte Carlo based simulation algorithms for finding feasible output paths and calculating impacts of input changes on tasks are developed in order to simulate the change propagation process. The objective function for scheduling design change propagations is obtained by the regression analysis of simulation results. And the best change propagation paths, which usually are not the real optimum of the original design process model, are given by optimizing the regression model with a commercial optimization package. The effect of the method is demonstrated with a study of change propagations in the motor cycle engine design process.     

Integration of product design,process planning,scheduling, and FMS control using XML data representation

An efficient model for communications between CAD, CAPP, and CAM applications in distributed manufacturing planning environment has been seen as key ingredient for CIM. Integration of design model with process and scheduling information in real-time is necessary in order to increase product quality, reduce the cost, and shorten the product manufacturing cycle. This paper describes an approach to integrate key product realization activities using neutral data representation. The representation is based on established standards for product data exchange and serves as a prototype implementation of these standards. The product and process models are based on object-oriented representation of geometry, features, and resulting manufacturing processes. Relationships between objects are explicitly represented in the model (for example, feature precedence relations, process sequences, etc.). The product model is developed using XML-based representation for product data required for process planning and the process model also uses XML representation of data required for scheduling and FMS control. The procedures for writing and parsing XML representations have been developed in object-oriented approach, in such a way that each object from object-oriented model is responsible for storing its own data into XML format. Similar approach is adopted for reading and parsing of the XML model. Parsing is performed by a stack of XML handlers, each corresponding to a particular object in XML hierarchical model. This approach allows for very flexible representation, in such a way that only a portion of the model (for example, only feature data, or only the part of process plan for a single machine) may be stored and successfully parsed into another application. This is very useful approach for direct distributed applications, in which data are passed in the form of XML streams to allow real-time on-line communication. The feasibility of the proposed model is verified in a couple of scenarios for distributed manufacturing planning that involves feature mapping from CAD file, process selection for several part designs integrated with scheduling and simulation of the FMS model using alternative routings.     

An integrated neuro-genetic approach incorporating the Taguchi method for product design

Product design is a multidisciplinary activity that requires the integration of concurrent engineering approaches into a design process that secures competitive advantages in product quality. In concurrent engineering, the Taguchi method has demonstrated an efficient design approach for product quality improvement. However, the Taguchi method intuitively uses parameters and levels in measuring the optimum combination of design parameter values, which might not guarantee that the final solution is the most optimal. This work proposes an integrated procedure that involves neural network training and genetic algorithm simulation within the Taguchi quality design process to aid in searching for the optimum solution with more precise design parameter values for improving the product development. The concept of fractals in computer graphics is also considered in the generation of product form alternatives to demonstrate its application in product design. The stages in the general approach of the proposed procedures include: (1) use of the Taguchi experimental design procedure, (2) analysis of the neural network and genetic algorithm process, and (3) generation of design alternatives. An electric fan design is used as an example to describe the development and explore the applicability of the proposed procedures. The results indicate that the proposed procedures could enhance the efficiency of product design efforts by approximately 7.8%. It is also expected that the proposed design procedure will provide designers with a more effective approach to product development.     

A method toward dynamic e-learning services modeling and the cooperative learning mechanism

The advanced information technologies have made it possible for individuals to carry out cooperative learning efficiently and effectively from anywhere and at any time. To capitalize on the individual need and address the issues associated with the late entry into the e-learning area, it has great significance to study the service mechanism of CSCL on e-learning service and e-learning service computing modeling. This paper proposes an e-learning service model supporting for the life-cycle process management. The proposed model is developed by considering the learner’s behaviours during e-learning services, the scheduling policies, and the monitoring mechanism of learning activities. Business process modeling for e-learning services can be taken according to the study ordering of the knowledge points by using workflow modeling technology and process enactment mechanism. The overall life-cycle process management of knowledge is addressed by combining knowledge product modeling, knowledge resource modeling, and credit polices for member selection in research team by considering trust value of learners, advisers and providers in e-learning services. The proposed method can be used for supporting the sustainable development of e-learning services from planning and design, organizing e-learning process, maintenance of the e-learning process, to process improvement, as well as to support learners and advisers to effectively complete innovative team study and complex computation study. Lastly, an extended topic map tool has been developed by adding a knowledge requirement level and an information extraction tool to validate the proposed methodology. These tools can used to guide learners to concentrate on the required knowledge topics and drive knowledge providers to redevelop outdated knowledge hierarchy.     

Analytical method of PID controller design for parallel cascade control

An analytical method of PID controller design is proposed for parallel cascade control. Firstly, a general structure for parallel cascade control is proposed that takes both setpoint and load disturbance responses into account. Analytical tuning rules for the PID controllers are then derived for the general process model by employing the IMC design procedure. The proposed method offers a simple and effective way to obtain the PID controller rules for parallel cascade control system which takes into account the interaction between primary and secondary control loops. The simulation results illustrate the application of the proposed method and demonstrate its superiority compared to several alternatives.     

Optimal concurrent design based upon distributed product development life-cycle modeling

This research introduces an optimal concurrent design approach based upon a previously developed distributed product development life-cycle modeling method. In this approach, the product realization process alternatives and relevant activities are modeled at different locations that are connected through the Internet. Relations among these alternative activities are described by an AND/OR graph. The optimal product realization process alternative and its parameter values are identified using a multi-level optimization method. Genetic programming (GP) and particle swarm optimization (PSO) are employed for identifying the optimal product realization process alternative and the optimal parameter values of the feasible alternatives, respectively.     

An algorithmic analysis of simulation strategies

Each discrete event simulation language incorporates a time control procedure to conduct timing management and next event selection. Each time control procedure embodies, and thus imposes, a strategy (approach, method) for next event selection- and thereby determines the world view of a language. The three generally recognized strategies are event scheduling, activity scanning and process interaction.This paper presents algorithmic formulations of the three strategies and their modeling routines, as well as detailed discussions and comparisons of the strategies. The algorithmic formulations serve to aid understanding by describing essential aspects of the strategies while excluding implementation details which are not strategy-dependent, and which tend to detract from the essential concepts.A significant practical application of the formulations is discussed. This consists of merging the algorithms for the event scheduling and process interaction strategies into one algorithm, which then served as a model for combining GPSS and GASP IV into a simulation system providing the individual capabilities of both language, and the capability to intermix GPSS and GASP within a single model.     

面向开源设计演化过程的产品-社区共生模型*

为探究开源设计的演化过程,本文首先对该过程的复杂性进行了分析;其次,建立了基于智能主体的产品-社区共生模型,该模型由多主体系统模型和产品关系模型组成,反映了人员、产品、社区的演化过程;最后,运用动态仿真技术对开源设计过程中的人员知识增长、产品进化周期、社区演化等方面进行了分析和评价。仿真实验结果证明了运用多主体建模与仿真方法对开源设计演化过程分析的有效性,为该过程的预测、管理和优化奠定了基础。