基于语义虚拟环境的虚拟人动画研究与实现*

现有虚拟环境建模（如VRML/X3D）主要集中在几何图形的描述,所显示的虚拟场景对于人是可理解的,但对于计算机是不可理解的,因而难以作有意义的自动处理。基于语义Web设计了一个语义虚拟环境（主要包括语义虚拟场景和语义虚拟人）,并设计了基于语义虚拟环境的虚拟人动画引擎。语义虚拟环境使得计算机能够理解和自动处理虚拟环境的语义信息,并且使得虚拟环境系统具有可重用性、可扩展性和可集成性。最后,在语义虚拟环境和虚拟人动画引擎的基础上开发了一个办公室场景中智能虚拟人行动推理的系统,取得了很好的效果。     

虚拟计算平台远程可信认证技术研究

与传统的单机系统按照可信平台模块、可信BIOS、操作系统装载器、操作系统内核的信任链传递方式不同,虚拟化计算环境信任链按照可信平台模块、可信BIOS、虚拟机监控器和管理虚拟机、用户虚拟机装载器、用户虚拟机操作系统装载器、用户虚拟机操作系统内核的方式进行.文章对虚拟计算平台远程完整性验证的安全需求进行了分析.为防止恶意的虚拟机监控器篡改虚拟机的完整性证明,文章提出虚拟机平台和虚拟机管理器两级的深度认证.在对虚拟机认证过程中,远程挑战者需要通过虚拟机或者直接与虚拟平台建立联系来认证平台的虚拟机管理器层.为防止中间人攻击,文章提出将物理平台寄存器映射到各虚拟平台寄存器的方式解决虚拟机与物理平台的绑定问题.     

Measuring virtual wealth in virtual worlds

This article presents pioneering research on measuring virtual wealth in an open virtual world for diagnosing the health of virtual worlds. It proved the existence of an open virtual world by proving the existence of a free choice of virtual currencies for virtual goods between distinct virtual worlds. By discussing the features of open virtual world in a circled networked organization, the article devised a virtual wealth measuring scheme, called Gross Virtual Product (GVP), for any virtual world. Based on this scheme, it suggested an accountability matrix to account for a changing virtual world regarding its total virtual wealth, profitability, user participation and happiness. To demonstrate the suitability of GVP scheme and accountability matrix, the article has conducted a case study on SecondLife.com, which showed the appropriateness of the proposed scheme and matrix. The research made in this article is very important. The proposed measuring scheme and matrix help virtual world participants perceive the possible risks of the participated virtual worlds in advance to make better decisions on virtual business.     

Virtual trackballs revisited

Rotation of three-dimensional objects by a two-dimensional mouse is a typical task in computer-aided design, operation simulations, and desktop virtual reality. The most commonly used rotation technique is a virtual trackball surrounding the object and operated by the mouse pointer. We review and provide a mathematical foundation for virtual trackballs. The first, but still popular, virtual trackball was described by Chen et al. (1998). We show that the virtual trackball by Chen et al. does not rotate the object along the intended great circular arc on the virtual trackball and we give a correction. Another popular virtual trackball is Shoemake's quaternion implementation (1992), which we show to be a special case of the virtual trackball by Chen et al.. Shoemake extends the scope of the virtual trackball to the full screen. Unfortunately, Shoemake's virtual trackball is inhomogeneous and discontinuous with consequences for usability. Finally, we review Bell's virtual trackball (1998) and discuss studies of the usability of virtual trackballs.     

微操作机器人系统拟实环境的建模与实现

建立微操作机器人的拟实环境结构, 应包括微操作环境的建模、微操作工具的建模及模型叠加三部分; 本文就微操作环境的建模与实现和微操作工具的建模与实现这两部分的关键技术: 图像传输、虚拟微操作器的生成、虚拟显微镜、虚拟成像过程及虚拟控制器给出了实现方案, 并在基于微机的硬件结构和VisualC ++及OpenGL组成的软件环境里, 得到了虚拟微操作环境和虚拟微操作工具的动态模型.     

Realization of reconfigurable virtual environments for virtual testing

1 Introduction The scalability of virtual environments (VEs) that allow users to change and modify their contents and context depending on application requirements has been a de facto feature of virtual reality technology. Engineering uses such as virtual testing and exper- imenting applications demand VEs to be highly or fully reconfigurable. In reality, however, satisfactory reconfiguration of a virtual environment is yet to be achieved, due to the high accuracy of spatial data in- put and…     

虚拟现实技术在化学实验教学中的应用研究

虚拟实验应用日益广泛,而支持虚拟实验的相关技术成为了研究热点。分析了虚拟化学实验及其在未来虚拟现实技术上的发展趋势,综述了U-nity3D技术、增强现实技术和Kinect体感交互技术的理论基础以及在虚拟化学实验中的应用与发展,以虚拟技术融合的方法为导向,仿真化学实验的实时环境,使虚拟实验简单化、直观化。展望了虚实融合技术在虚拟实验领域的应用前景。虚实融合技术有利于推动虚拟化学实验朝智能化发展,是虚拟实验改革的一个新起点。     

Virtual distributed environments in a shared infrastructure

We have developed a middleware system that integrates and extends virtual machine and virtual network technologies to support mutually isolated virtual distributed environments in shared infrastructures like the grid and the PlanetLab overlay infrastructure. Integrating virtual network and on-demand virtual machine creation and customization technologies makes virtual distributed environments a reality. The Violin-based middleware system integrates and enhances such technologies to create virtual distributed environments.     

基于增强型虚拟机的软件保护技术

针对目前日益严峻的软件保护问题,对现有基于虚拟机的软件保护技术进行分析与研究,对虚拟机保护技术进行了改进,设计了一种增强型虚拟机软件保护技术。采用了虚拟花指令序列与虚拟指令模糊变换技术,并对虚拟机的虚拟指令系统做了改进,从而提高了虚拟机执行的复杂程度与迷惑程度,具有高强度的反逆向、防篡改、防破解的特点。实验分析表明,增强型虚拟机保护技术明显优于普通型虚拟机保护技术。     

沉浸式虚拟训练中的虚拟手操控技术研究

将人手的自然动作加入沉浸式虚拟现实系统中,可有效提高系统的沉浸感和交互性,简便快捷、成本低廉的虚拟手建模及操控技术,有助于此项内容的推广应用;在对虚拟手骨骼结构模型分析的基础上,提出了基于Leap Motion的虚拟手控制方法和流程;以维修训练为任务背景,设计了四种用于虚拟手操作的手势规则,并对实现流程和关键技术进行了分析;构建基于Unity3D引擎的原型系统对虚拟手进行仿真验证,结果表明,基于Leap Motion的虚拟手操控简单、交互自然,可以满足虚拟现实系统交互需要。     

基于数据构造的仿真技术及应用

介绍了基于数据构造虚拟原型开发技术的概念及两个关键技术，通过和现有虚拟原型开发技术比较，给出基于数据构造虚拟原型技术的优点。着重分析在计算机虚拟实验系统开发过程中，如何通过数据构造计算机虚拟器件，以及如何利用数据驱动机制通过虚拟器件的数据模型来实现器件的功能、属性，并最终实现整个虚拟实验。     

虚拟手交互中约束类物体操作研究

虚拟手技术是虚拟现实技术中的一种交互方式，是指通过手势识别技术将人的真实手映射到虚拟环境中并与虚拟物体进行交互操作的人机交互方式。主要应用于虚拟训练、虚拟手术和虚拟装配等领域。对虚拟手交互的约束类对象进行了研究，提出了基于运动学的约束类物体操作方法，解决了阀门类有约束物体交互中虚拟手姿态不真实、操作不可控的问题。设计实验验证了基于运动学的方法能以符合实际操作的效果完成虚拟现实系统中的操作任务，可以应用到虚拟训练、虚拟装配等仿真平台。     

Surviving the paradoxes of virtual teamwork

Despite the potential benefits of virtual teams, current literature suggests that virtual teamwork is rife with complex challenges. We frame some of these challenges as paradoxes inherent in the concept of virtual teamwork. Based on interviews with 42 leaders and members of virtual teams, we identify five paradoxes: (1) virtual teams require physical presence; (2) flexibility of virtual teamwork is aided by structure; (3) interdependent work in virtual teams is accomplished by members' independent contributions; (4) task-oriented virtual teamwork succeeds through social interactions; and (5) mistrust is instrumental to establishing trust among virtual team members. In addition, we identify strategies that respondents used to cope with, or 'survive' the paradoxes of virtual teamwork.     

Xen虚拟机的虚拟CPU松弛协同调度方法

目前,Xen虚拟机调度算法均采用独立调度虚拟CPU的方式,而没有考虑虚拟机各虚拟CPU之间的协同调度关系,这会使虚拟机各个虚拟CPU之间产生很大的时钟中断数量偏差等问题,从而导致系统不稳定.为了提高系统的稳定性,基于Credit算法提出了一种比RCS(relaxed co-scheduling)算法更松弛的协同调度算法MRCS(more relaxed co-scheduling).该算法采用非抢占式协同调整方法将各个虚拟CPU相对运行的时间间隔控制在同步时间检测的上限门限值Tmax之内,同时利用同步队列中虚拟CPU优化选择调度方法和Credit算法的虚拟CPU动态迁移方法,能够更加及时地协同处理虚拟CPU,并且保证了各个物理CPU的负载均衡,有效地减少客户操作系统与VMM的环境切换次数,降低了系统开销.实验结果证明该方法不但保证了系统的稳定性,而且使系统性能得到一定程度的提升.虚拟机调度算法不仅影响虚拟机的性能,更会影响虚拟机的稳定性,致力于虚拟机调度算法的研究是一项非常有意义的工作.     

虚网络及其协议

本文提出了的虚网络是一种逻辑网络。它与物理网络之间关系类似虚拟存储器与物理存储器间的关系，无论主机移动与否，其相对虚网络的位置不变，这解决了移动主机在网络中位置标识问题，对应与物理网络地址又提出了虚网络地址。     

基于物理的图形建模研究

逼真性是虚拟现实的重要特性,也是虚拟现实研究的难点。基于物理的图形建模是实观虚拟环境中物体逼真运动的基本方法,它构建动画角色的动力学模型并通过仿真计算它们的运动。该方法在视频制作、虚拟仿真、虚拟漫游等领域中具有重要的应用价值。与其它运动表示方法相比,可以实现虚拟环境中多种更为逼真的物体运动效果。该文分别以不变形物体（刚体）和变性物体（柔体）为例,介绍了虚拟现实系统中实现逼真物体运动的基于物理的建模思想,分析了它们的特点以及各自存在的问题和局限性。最后指出了要想理想解决物体建模问题所必须进一步研究和突破的若干技术。     

虚拟环境中微机械拟实组装的运动学描述

微机械的组装包括：部件制作,部件对准和部件焊接 ３个过程．本文针对微机械组装中最重要对准过程,给出了虚拟环境中拟实组装细化的操作 步骤及相应的运动学描述．同时,面向微机械拟实运行,给出了焊接过程的运动学描述．建 立了虚拟现实实验平台,并在此平台上完成了一个作为虚拟环境中微马达转子与定子拟实组 装简化例子的轴孔配合拟实组装实验．初步验证了本文所给出的虚拟环境中拟实组装运动学 描述的正确性．     

Adapting grid computing environments dependable with virtual machines: design, implementation, and evaluations

Due to its potential, using virtual machines in grid computing is attracting increasing attention. Most of the researches focus on how to create or destroy a virtual execution environments for different kinds of applications, while the policy of managing the virtual environments is not widely discussed. This paper proposes the design, implementation, and evaluation of an adaptive and dependable virtual execution environment for grid computing, ADVE, which focuses on the policy of managing virtual machines in grid environments. To build a dependable virtual execution environments for grid applications, ADVE provides an set of adaptive policies managing virtual machine, such as when to create and destroy a new virtual execution environment, when to migrate applications from one virtual execution environment to a new virtual execution environment. We conduct experiments over a cluster to evaluate the performance of ADVE, and the experimental results show that ADVE can improve the throughput and the reliability of grid resources with the adaptive management of virtual machines.     

浅析计算机通信中虚拟现实技术的实用

虚拟现实技术是通过三维交互式计算机的制作而创造一些虚拟的环境,从而对现实的事物进行虚拟规划和分析的过程,其主要的特征表现在虚拟现实技术的构想性、沉浸感、和全息性、交互性.该文通过虚拟现实技术的概念和特征出发,对计算机通信中虚拟显示技术的应用现状进行具体的分析.     

基于计算机动画的虚拟导游技术及其应用

基于虚拟现实技术的虚拟旅游正蓬勃发展,正如导游在旅游业的重要地位一样,虚拟导游也是虚拟旅游技术的重要组成部分。该文利用计算机人物建模和动画技术,实现了基于计算机动画的虚拟导游,有效地增强了虚拟旅游场景的趣味性和真实感。讨论了基于计算机动画的虚拟导游的关键技术,并将其应用于虚拟旅游系统,效果良好。