宜春市状元洲抬水工程设计浅析

以江西省宜春市状元洲抬水工程为实例,探讨了橡胶坝及升卧式闸门在抬水工程中的设计及应用.     

A Robust Controller for A 3‐DOF Flexible Robot with a Time Variant Payload

This article describes a new control scheme designed for a three degree of freedom (3‐DOF) flexible robot. The control scheme consists of two multi variable control loops. The inner loop is the motor's position control system, while the outer loop controls the robot tip's position, thus canceling vibrations which are originated by the structural flexibility of the manipulator during movement. As it will be shown, the outer control loop is robust to payload variations. The outer loop performance is based on a perfect cancelation of the inner loop dynamics. The effects of not achieving such perfect cancelation are also studied, and rules for designing a robust controller in this case are developed. Simulations assuming different payloads have been carried out with successful results for trajectory tracking. Trajectory tracking with a variable payload is also achieved.     

凸多面体快速碰撞检测的投影分离算法

为了有效地提高凸面体之间的碰撞检测效率,提出一种凸多面体快速碰撞检测的投影分离算法.该算法通过判断2个凸多面体在中心线上的正投影不相交,或者分别构造它们的准投影分离面集合,并从这2个集合中找到一个投影分离面,来判断2个凸多面体分离;否则,判断为相交.对于2个准投影分离面集合,依次交替地判断它们的每一个面是投影分离面还是相交面,以加快2个凸多面体相交检测.计算复杂度分析和数值实验表明:该算法平均检测效率高于其他检测算法.     

虚拟装配中基于精确模型的碰撞检测算法

针对目前虚拟装配中由多边形模型引起的碰撞检测准确性低的问题,提出一种考虑公差信息的精确碰撞检测算法.首先进行分层的多边形碰撞检测,获得发生碰撞的多边形;然后基于层次图像数据将发生碰撞的多边形映射到零件相应的几何上;再依据几何的公差信息计算碰撞阈值;最后根据碰撞阈值进行精确碰撞判定.实例验证结果表明,文中算法在保证虚拟装配系统实时性的同时,提高了碰撞检测的准确性.     

《GIS软件工程》实验模式研究

GIS软件工程实验是《GIS软件工程》教学过程中的重要环节,分析《GIS软件工程》的特点,结合在教学实验过程中具体的问题,提出基于柔性案例的GIS软件工程实验模式,并从柔性案例的选择、柔点的选择设置方法、实验过程等方面,分别展开描述,对实验实施中的优缺点进行总结。     

一种支持柔性的工作流过程元模型

工作流管理系统的动态自适应能力在很大程度上取决于过程模型的动态支持能力。本文分析和讨论了过程模型的动态特性和工作流管理联盟WfMC定义的过程元模型。在此基础上,引入柔性工作流定义、同步器、变换器等新元素,改进和扩展过程定义元模型。改进和扩展后的过程元模型具有更大的柔性和重构性。由于引入了变换器,为增强过程元模型的智能性做了基础性工作。另外,对描述过程元模型的定义语言WPDL也做了改进和扩展。     

3D游戏开发中的碰撞检测算法研究

碰撞检测在三维游戏开发中是必不可少的环节。目前,主流游戏引擎大多采用基于层次包围体的碰撞检测算法,其基本思想是用一个相对简单的包围体逼近场景中复杂的物体。文中对当前三维游戏开发中常用的四种基于包围体的算法作了理论分析,并通过试验对四种不同的包围体算法作了性能测试。试验结果表明,紧密性越好的包围体其精度越高,但时间消耗也高。因此,在具体的游戏开发中,应根据实际游戏的特殊情况进行算法选用,才能取得较好的效果。     

灵活QinQ技术在校园网中的设计与实现

高校校园网普遍存在IP盗用、IP冲突、二层广播严重等问题,且一直没有一个较为完善的解决方法。中国矿业大学校园网采用灵活QinQ+DHCP网络模式,通过BRAS建立双层标签,DHCP自动分配IP,交换机端口二层隔离,创造性的解决了这一长期困扰我们的问题。     

High Performance GPU‐based Proximity Queries using Distance Fields

Proximity queries such as closest point computation and collision detection have many applications in computer graphics, including computer animation, physics‐based modelling, augmented and virtual reality. We present efficient algorithms for proximity queries between a closed rigid object and an arbitrary, possibly deformable, polygonal mesh. Using graphics hardware to densely sample the distance field of the rigid object over the arbitrary mesh, we compute minimal proximity and collision response information on the graphics processing unit (GPU) using blending and depth buffering, as well as parallel reduction techniques, thus minimizing the readback bottleneck. Although limited to image‐space resolution, our algorithm provides high and steady performance when compared with other similar algorithms. Proximity queries between arbitrary meshes with hundreds of thousands of triangles and detailed distance fields of rigid objects are computed in a few milliseconds at high‐sampling resolution, even in situations with large overlap.     

Continuous collision detection for adaptive simulation of articulated bodies

We perform continuous collision detection (CCD) for articulated bodies where motion is governed by an adaptive dynamics simulation. Our algorithm is based on a novel hierarchical set of transforms that represent the kinematics of an articulated body recursively, as described by an assembly tree. The performance of our CCD algorithm significantly improves as the number of active degrees of freedom in the simulation decreases.