Priority-based haptic event filtering for transmission and error control in networked virtual environments

A data filtering scheme is proposed for transmission and error control of haptic events in haptic-based network virtual environments; this scheme is called as priority-based haptic event filtering. Because a high update rate of approximately 1 kHz is required for haptic rendering, sophisticated transmission rate control and reduction schemes are necessary for the haptic events. Although existing schemes can reduce the transmission rate without any perception impairment, they are very sensitive to packet losses. In this paper, we prioritize the haptic events according to the delay and loss effects. Utilizing the proposed haptic event prioritization, the proposed filtering scheme adapts the transmission rate and updates the predicted loss rate according to the current network state. Our simulation and experiment results confirm that the proposed scheme can effectively select important haptic events and guarantee an improved haptic interaction quality over a bandwidth-limited lossy network than existing transmission schemes tailored for networked haptics.     

Transparency analysis and delay compensation scheme for haptic-based networked virtual environments

Haptic-based NVEs (networked virtual environments) with CS (client/server) communication architectures support better consistency but induce larger end-to-end delays than those with P2P (peer-to-peer) communication architectures. Unfortunately, large delay severely deteriorates the transparency (i.e., reality) of haptic interaction. To improve the haptic interaction quality for haptic-based NVEs with CS communication architectures, in this paper the degradation of haptic interaction quality is analyzed according to network delays. Based on the analysis, the maximum allowable delay bound is predicted and unrealistic force feedback caused by the network delay is compensated. Experimental results confirm that the proposed analysis provides an acceptable quantification method about haptic interaction quality and that the proposed delay-compensation scheme effectively improves haptic interaction quality with respect to network delays.     

开放式环境下一种基于信任度的RBAC模型

在开放式环境中,用户和资源的高流动性会导致基于角色的访问控制(RBAC)模型在角色指派和权限控制方面异常复杂。为此,提出一种基于信任度的弹性RBAC模型。利用评价机制确定用户与资源间的直接信任度及资源之间的推荐信任度,综合2种信任度计算用户的信任度和资源的权威度,结合用户的访问记录,为用户分配合理的角色和权限,并采用加性增、乘性减算法动态调整实体的信任度,从而防止恶意行为。基于Query Cycle Simulator的实验结果证明,该模型可以保证评价的合理性和准确性。     

Fault-tolerant feedback virtual machine deployment based on user-personalized requirements

A key requirement of the cloud platform is the reasonable deployment of its large-scale virtual machine infrastructure. The mapping relation between the virtual node and the physical node determines the specific resource distribution strategy and reliability of the virtual machine deployment. Resource distribution strategy has an important effect on performance, energy consumption, and guarantee of the quality of service of the computer, and serves an important role in the deployment of the virtual machine. To solve the problem of meeting the fault-tolerance requirement and guarantee high reliability of the application system based on the full use of the cloud resource under the prerequisite of various demands, the deployment framework of the feedback virtual machine in cloud platform facing the individual user’s demands of fault-tolerance level and the corresponding deployment algorithm of the virtual machine are proposed in this paper. Resource distribution strategy can deploy the virtual machine in the physical nodes where the resource is mutually complementary according to the users’ different requirements on virtual resources. The deployment framework of the virtual machine in this paper can provide a reliable computer configuration according to the specific fault-tolerance requirements of the user while considering the usage rate of the physical resources of the cloud platform. The experimental result shows that the method proposed in this paper can provide flexible and reliable select permission of fault-tolerance level to the user in the virtual machine deployment process, provide a pertinent individual fault-tolerant deployment method of the virtual machine to the user, and guarantee to meet the user service in a large probability to some extent.     

D3DPR:基于Direct3D9的并行图形绘制系统

根据Direct3D9图形库的特征,提出了支持Direct3D9应用程序级透明并行图形绘制系统D3DPR的系统结构及其实现原理.D3DPR分为资源分配和资源绘制2类逻辑节点.通过资源分配节点并行图形库DPGL的截取技术和资源绘制节点的重构技术,任何单机的Direct3D9应用程序都不需要经过修改即可实时转变为由PC集群并行绘制,从而得到更高的绘制性能和高分辨率的多屏拼接显示效果,为用户提供具有更强真实感和沉浸感的虚拟环境.     

具有高可靠特征的无线虚拟网络映射方法研究

针对虚拟网络映射过程中链路资源受限和网络生存性问题，分别提出一种基于节点扩展资源的节点映射方案和一种虚拟网络重映射方案。为克服节点映射后链路映射阶段的资源不足问题，通过将节点扩展资源大的节点作为承载节点以确保链路映射的可靠性和高效性，链路映射阶段采用一种基于最小链路代价的映射方案以获得高可靠映射，在此基础上针对网络故障采取一种重映射策略，将失效节点迅速重映射至候选节点集中以确保虚拟网络服务的连续性。通过仿真对几种算法性能进行对比，结果表明所提算法在虚拟网络映射成功率、虚拟网络恢复成功率和资源负载利用率等方面均取得较好结果。     

A hybrid haptic guidance model for tank gunners in high precision and high speed motor skill training

Haptic-based paradigms for human motor skill training which include virtual fixture, record-play method, shared control scheme and haptic disturbance have been proposed and widely used for applications like surgery, assembly, rehabilitation, motor skill and so on. However, no haptic-based training scheme applies to all types of human motor skills that new ideas and new approaches should be explored for some special training tasks. For example, tank gunners have to be rigorously trained to be able to complete the most accurate manipulation in the shortest possible time. Accuracy and operating speed are both critical for them to grasp the skill; therefore, tank gunnery is defined as a type of high precision and high speed human motor skill. In this paper, a hybrid spring-damper model which fuses haptic fixture and record-play is presented to simultaneously train accuracy and operating speed. The training approach is suitable for novices at all levels since force feedback is decomposed into two components: one for training accuracy, the other for training speed. The virtual envelope depicting is chosen as the training task for novices to validate the effectiveness of the proposed haptic-based scheme in high precision and high speed skill training. Experimental results indicate that force feedback generated based on the hybrid model can benefit novices in fast improving performances on tank gunnery.     

Failure-aware resource management for high-availability computing clusters with distributed virtual machines

In large-scale networked computing systems, component failures become norms instead of exceptions. Failure-aware resource management is crucial for enhancing system availability and achieving high performance. In this paper, we study how to efficiently utilize system resources for high-availability computing with the support of virtual machine (VM) technology. We design a reconfigurable distributed virtual machine (RDVM) infrastructure for networked computing systems. We propose failure-aware node selection strategies for the construction and reconfiguration of RDVMs. We leverage the proactive failure management techniques in calculating nodes’ reliability states. We consider both the performance and reliability status of compute nodes in making selection decisions. We define a capacity–reliability metric to combine the effects of both factors in node selection, and propose Best-fit algorithms with optimistic and pessimistic selection strategies to find the best qualified nodes on which to instantiate VMs to run user jobs. We have conducted experiments using failure traces from production systems and the NAS Parallel Benchmark programs on a real-world cluster system. The results show the enhancement of system productivity by using the proposed strategies with practically achievable accuracy of failure prediction. With the Best-fit strategies, the job completion rate is increased by 17.6% compared with that achieved in the current LANL HPC cluster. The task completion rate reaches 91.7% with 83.6% utilization of relatively unreliable nodes.     

高效可撤销的雾协同云访问控制方案

密文策略属性加密技术在实现基于云存储的物联网系统中数据细粒度访问控制的同时,也带来了用户与属性的撤销问题。然而,在现有的访问控制方案中,基于时间的方案往往撤销并不即时,基于第三方的方案通常需要大量重加密密文,效率较低且开销较大。为此,基于RSA密钥管理机制提出了一种高效的支持用户与属性即时撤销的访问控制方案,固定了密钥与密文的长度,借助雾节点实现了用户撤销,同时将部分加解密工作从用户端卸载到临近的雾节点,降低了用户端的计算负担。基于aMSE-DDH假设的安全性分析结果表明,方案能够抵抗选择密文攻击。通过理论分析和实验仿真表明,所提方案能够为用户属性变更频繁且资源有限的应用场景提供高效的访问控制。     

面向云计算的多虚拟机管理模型的设计

提出基于P2P结构的多虚拟机管理模型,并实现其原型系统。采用P2P结构组织宿主机节点,利用组播实现资源发现;提出虚拟机动态迁移算法,自主触发节点间虚拟机动态迁移;利用选举的根节点映射云计算用户请求至宿主机,实现节点上虚拟机的按需创建、删除及停止等操作。实验表明:该模型具有收敛时间短、带宽占用率低及高可用性的特点,能够实现云计算资源的动态负载均衡。     

Development scheme of haptic-based system for interactive deformable simulation

This paper aims to develop a novel scheme for interactively deformable simulation with haptic feedback. All design modules are packaged and implemented, and the experiments are conducted to study the effects of interactive deformation. The study compares the experimental results of haptic feedback by different force propagation methods, according to the Hounsfield unit (HU) of volume data. Additionally, the estimation of optimal propagation depth is illustrated by using a mass-spring model. Finally, by using the proposed scheme, a haptic-based medical simulation system for brain surgery is investigated. The integration test results with haptic feedback scenarios show that the proposed development scheme can certainly comply with the design modules, and the deformable simulation and haptic force reach a good agreement.     

基于Internet的多用户共享虚拟环境框架的研究

多用户共享虚拟环境是指网络化的协同虚拟现实系统，在该环境中多个用户之间通过各自的三维图形表示实现在虚拟环境中的多人感知，用户之间的交互以及对虚拟对象的协同操纵，在综合分析现有系统以及Internet的开放性标准化需求基础上，提出了一种基于Internet的多用户共享虚拟环境解决方案，即多用户共享虚拟环境框架（multi-user shared virtual envitonment framework,MSVEF)，该框架描述了多用户虚拟环境的体系结构，定义了基于XML的相关交互协议，通过在原型系统中的初步应用，证明该框架可以支持不同网络平台的用户在同一个虚拟场景中的再现与交互。     

节点与链路协同映射的生存性虚拟光网络映射算法

针对弹性光网络中单链路故障问题,提出一种基于匈牙利算法求解链路映射方案的节点与链路协同映射保护算法CMST-HA。将虚拟网络请求的节点与链路分别划分为主动类型与被动类型,把主动类型节点映射至邻接链路频谱资源丰富且邻接节点计算资源充足的物理节点上,在主动链路时使用匈牙利算法求解出最小映射开销方案并完成映射,确定被动节点的映射位置,利用KSP算法为被动链路选择映射路径,在此基础上为虚拟网络请求的最小生成树链路提供备份路径。仿真结果表明,与RVNM、CMST算法相比,CMST-HA算法不仅能够降低虚拟网络请求阻塞率,而且可增加物理网络收益。     

基于私有云平台的云主机资源监控方案

针对传统网格计算中的监控工具已无法满足云计算平台中虚拟资源监控的问题,本文基于OpenStack云平台设计并实现一套完整的私有云平台中云主机资源监控方案.实验表明该方案可以有效地进行虚拟资源的监控,满足企业私有云中对虚拟资源的监控需求,且系统方案具有良好的可扩展性.     

基于机群的拼贴显示系统的软件结构

利用计算机系统控制多个图形部件,驱动多个投影仪得到基于投影拼贴的显示,是突破现有显示技术制约,实现千万像素以上的高清晰度大尺寸显示的有效手段。目前采用PC机群系统来驱动拼贴显示系统的方式由于其较高的性能价格比正日益成为主流的选择,但是这种实现方式同时需要更复杂的分布式显示软件的支持。该文分析比较了几种基于机群的拼贴显示系统的软件结构并在此基础上提出了一种新的适合并行程序环境的软件接口。     

A resource selection scheme for QoS satisfaction and load balancing in ad hoc grid

Ad hoc grids are highly heterogeneous and dynamic, in which the availability of resources and tasks may change at any time. The paper proposes a utility based resource selection scheme for QoS satisfaction and load balancing in ad hoc grid environments. The proposed scheme intends to maximize the QoS satisfaction of ad hoc grid users and support load balancing of grid resources. For each candidate ad hoc grid resource, the scheme obtains values from the computations of utility function for QoS satisfaction and benefit maximization game for ad hoc grid resource preference. The utility function for QoS satisfaction computes the utility value based on the satisfaction of QoS requirements of the grid user request. The benefit maximization game for grid resource node preference computes the preference value from the resource point of view. Its main goal is to achieve load balancing and decrease the number of resource selection failure. The utility value and the preference value of each candidate ad hoc grid resource are combined to select the most suitable grid resource for ad hoc grid user request. In the simulation, the performance evaluation of proposed algorithm for ad hoc grid is conducted.     

基于用户需求的内容分发点对点网络系统研究

点对点内容分发网络技术已成为近年来研究热点领域之一.为用户推荐有价值的资源,提高用户资源定位的准确率和分发效率,是CDN-P2P技术面临的巨大挑战.从用户需求的角度出发,综述了近年来CDN-P2P领域的研究状况：讨论了用户需求并介绍了需求获取方法;对基于用户需求的CDN-P2P系统模型、节点特征及用户相似性、用户之间的相互关系、节点安全性和搜索机制等进行了对比讨论和概括总结;对基于用户需求CDN-P2P领域存在的难点和热点问题作了深入的剖析;最后给出了基于用户需求的CDN-P2P系统的发展趋势及其展望.     

A Global Optimal Mapping Method of Network based on Discrete Optimization Firefly Algorithm

In order to solve the current network rigidity and optimize the resource requirements of multiple virtual networks for synchronous mapping, improve the success rate of virtual network mapping requests, the long-term revenue and overhead ratio of the substrate network, node resource utilization rate and link resource utilization rate. A global optimal mapping method based on discrete optimization firefly algorithm is presented. Analyze the problem of virtual network mapping, map virtual nodes to physical nodes, and map virtual links to physical paths. According to the resource constraints of the virtual network and the substrate network, a multi-objective optimization model of the virtual network mapping is constructed, and the discrete fireflies optimization algorithm is used to obtain the global optimal solution of the virtual network mapping model to achieve the optimal allocation of global resources. The experimental results show that the discrete optimization firefly algorithm has a good performance in solving the virtual network mapping problem, and can effectively improve the virtual network request acceptance rate, node resource utilization rate, link resource utilization rate, and long-term revenue and cost ratio of the substrate network, ensuring Optimization of virtual network resources.     

小型化柔性触觉再现装置

提出了一种小型化的具有实时触觉反馈作用的人机接口装置的设计方法,以控制弹性梁的有效变形长度为核心,保证了触觉再现的实时性和准确性,从而可以在操作者指端大范围再现虚拟对象或远程对象的刚度。介绍了该小型化人机触觉再现接口装置的硬件设计和软件设计。该实时触觉再现接口具有尺寸小、刚度再现范围大,可方便与鼠标相结合等特点,可广泛应用于遥操作机器人和虚拟现实领域。