A virtual plant modeller (VPMOD) for batch-chemical processes

This paper presents a virtual plant modeller (VPMOD), which formally characterizes and integrates chemical product designs, batch-chemical equipment (plants), the real-time scheduling of chemical batches, and the control of chemical transport through the plant. These models provide a framework for agile batch-chemical manufacturing that has the ability to reroute and control chemical product flow automatically in a flexible plant subject to unexpected events, such as changes in demand patterns and equipment failure. A formal logic model is generated to control the actual system events, which are non-deterministic. A simulation environment in VPMOD is used to validate schedules and control logic based on plant models supplied by industry. The formal models have been implemented in an object-oriented language.     

基于Jack的虚拟环境中一种防止穿越的实现

在虚拟环境下虚拟人手和虚拟物体的交互中,会发生穿越现象。为了解决穿越问题,在人体模型系统Jack的虚拟环境中,根据约束Constraint对象的特点,利用Constraint对象来模拟物体对人手阻挡作用,并利用约束队列实现了对场景中Constraint对象的管理,达到防穿越的效果。     

LabView实现远程数据采集与传输

阐述了在NI Lab View平台上结合TCP/IP协议进行数据传输的工作方法，并给出对工业现场数据采集传送与监控的仿真实例。     

类的多态性研究

从必要性入手探讨多态性的由来,从内存管理机制探讨多态性的实现机理.     

基于网上开放虚拟实验室的研究与设计

首先对网上开放虚拟实验室的基本概念、体系结构和管理模式进行介绍,分析了设计网上开放虚拟实验室的关键技术。最后设计和实现了网上开放虚拟实验室。     

Evaluation of markov program models in virtual memory systems

A first order Markov model of program behaviour is developed from FORTRAN program instruction data. The program model is evaluated by using it to generate page references for input into a simple virtual memory operating system (VMOS) simulation model. The actual trace data are also used to drive the VMOS model. In both cases the fault probability is obtained for different replacement rules, memory sizes and page sizes. A comparison of fault probabilities is used to determine the effectiveness of the Markov program model.     

Generating a learning stance through perspective-taking in a virtual environment

Emerging media technologies such as virtual environments present a unique opportunity to examine the effects of perspective-taking on processes of human learning. In these environments it is possible for learners to immerse themselves in a unique visual perspective—such as that of a competent actor—and experience the ways they allocate their attention as they perform critical tasks in a domain. This study investigates whether the opportunity to experience a first-person perspective of actions in a virtual world simulation benefits learning compared to a third-person, disembodied perspective of those same events. Measures of performance within the simulation and post-assessment activities including a diagramming task indicate significant advantages for participants who received the first-person perspective. These participants had a better memory for the important tasks and task-related elements of the simulation; they committed fewer errors and exhibited less help-seeking behavior than participants with a third-person perspective. Results are described in terms of a virtual environment’s ability to generate a learning stance through person-centered perspective-taking, and potential implications for the design of instructional computer technologies are discussed.     

基于虚拟仪器的活塞杆弯曲试验测试系统

利用NI公司的LabVIEW软件和PCI-6220数据采集卡,开发了基于虚拟仪器的测试系统,并在减振器活塞杆弯曲试验中加以应用.该测试系统通过对活塞杆弯曲过程中力和挠度的实时测试,实现了弯曲力-挠度曲线和加载速度的实时显示,完成了活塞杆屈服弯曲力、最大弯曲力、最大挠度、指定挠度处的弯曲力和指定弯曲力处的永久变形等参数的测试.实验结果表明,该测试系统具有使用方便、界面友好、性能完善、测试精度稳定等特点.     

450A接触电流测试仪测试网络和数据采集的设计

本文介绍了450A接触电流测试仪关键技术内容。     

Rapid identification technique for virtual CNC drives

This paper presents a technique for rapid identification of machine tool drives by conducting a short G-code test. The proposed strategy uses commanded and measured axis profiles and requires minimal intervention to the servo control loop. The drive system is identified as a whole, including the feed mechanism, motor, amplifier, and the control law. The methodology is fairly general and applicable to linear or ball screw drives, controlled with commonly used controllers like P, PI, PID, P–PI Cascade or Adaptive Sliding Mode Control; with or without feedforward dynamic or friction compensation. In order to guarantee the stability of identified dynamics, bounds are imposed on the pole locations. The identified models can be used in a Virtual CNC system for predicting the contouring and tracking errors to different part programs. Simulation and experimental case studies are presented, where tracking and contour errors are successfully predicted using drive models identified with the proposed strategy.