虚拟维修技术及其在装备维修上的应用

虚拟维修是虚拟现实技术在维修领域的具体应用.文章介绍了虚拟维修的定义和虚拟维修的特点,探讨了在装备维修训练上的应用.     

虚拟维修中虚拟人的动作模型设计

提出了一种基于维修任务分解的虚拟人动作模型设计方法,将虚拟维修任务分解为三个过程,建立了三个相应的维修动作层次化模型,阐述了维修动作的分类与设计,并将维修动作模型应用到了虚拟维修过程中.实验结果表明,基于维修任务分解的虚拟人动作模型可以有效地将虚拟人技术应用到虚拟维修中,大大提高了虚拟维修的逼真性.     

虚拟维修技术发展综述

作为一门新兴的技术科学,虚拟维修已经引起工业界和学术界的广泛关注.通过归纳比较虚拟维修与虚拟装配、维修仿真、维修性可视化等技术的区别和联系,分析了虚拟维修的技术内涵,总结了虚拟维修技术的特点、研究内容和关键技术,从狭义和广义2个角度给出了虚构维修技术的定义;指出了该技术目前存在的问题和今后的发展趋势.     

虚拟维修模型的校验方法研究

介绍了虚拟雏修与建模仿真的关系,分析了虚拟维修模型校验的特点,研究了虚拟维修模型校验的方法,分别应用置信区间法、假设检验法、Bayes法、TIC法、频谱分析法从静态性能和动态性能两个方面对模型实施校验,从而为虚拟维修模型准确性、实时性提供了较为可靠的验证方法.为虚拟维修模型的校验提供一套系统的理论和方法,有利于虚拟维修模型得到更好应用.     

某型导弹虚拟维修训练系统设计研究

本文在分析结合实装进行维修训练缺点的基础上,提出了基于虚拟现实技术、虚拟样机技术和过程仿真技术的某型导弹虚拟维修训练系统设计方法,研究了系统的构成,将系统划分为虚拟样机和虚拟维修过程仿真控制两大部分,阐述了每部分的组成和实现方法。所设计的虚拟维修训练系统在某型导弹装备上得到了成功地应用。     

虚拟维修技术及其在装备维修上的应用

虚拟维修是虚拟现实技术在维修领域的具体应用。文章介绍了虚拟维修的定义和虚拟维修的特点，探讨了在装备维修训练上的应用。     

虚拟维修训练系统中数据库的应用

数据库技术在虚拟维修训练系统中起着重要的作用。文章以MySQL数据库为例简述了数据库特点,分析了应用数据库的虚拟维修训练系统的优势,介绍了虚拟维修训练系统中数据库设计的基本方法,结合Torque Game Engine三维引擎开发了具有较好可移植性的虚拟维修训练系统。实验结果表明,将数据库技术应用到虚拟维修训练系统,可以有效提高系统开发的效率。     

虚拟维修训练系统关键技术研究与应用

虚拟维修技术弥补了传统维修训练过程的不足。简述虚拟维修技术,给出虚拟维修训练系统的开发框架,详细阐述其关键技术:三维模型构建技术、交互技术、碰撞检测技术和组件式脚本封装技术。其中三维模型构建中模型优化技术改善了系统中模型渲染的速度;组件式脚本封装技术根据组件复用的思想,对相似脚本的封装进行有效管理,该技术已应用于某基地的虚拟维修训练系统的开发过程,应用结果表明该方法的有效性。所提及的设计方法和技术可应用于其他虚拟维修训练系统或虚拟现实系统。     

基于P-Agent的虚拟维修样机交互特性建模方法

为了有效提高虚拟维修仿真中的虚拟维修样机部件的实时和自然的交互方式,根据虚拟维修仿真需求和交互支持,提出了基于P-Agent的虚拟维修样机交互特性建模方法.给出了P-Agent的定义与交互模型的定义,围绕虚拟维修中交互的实时性和自然性两大要素展开研究,对通信过程中的交互方式进行了设计,针对通信原语无法支持自然交互存在的不足,对通信原语进行了扩充,使其能够支持P-Agent之间更高层次、更复杂、更多交互协作的交互.仿真过程表明,应用改进的建模方法可以实现良好自然的交互,能够满足实时的虚拟维修仿真交互,具有通用性.     

基于弱化Agent的虚拟维修样机行为建模方法

为了建立具有行为和反应能力的虚拟维修样机行为模型,真正体现虚拟样机的模型特征,引入基于弱化Agent的建模方法对虚拟维修样机进行行为建模。给出了弱化Agent的特点和行为定义模式,研究了虚拟维修环境下行为模型的表示,行为模型的划分和行为模型的输出,给出了行为建模的具体实现过程,并把上述方法应用于某大型设备虚拟维修样机模型的行为建模中。通过应用实例可以看出应用此方法进行虚拟维修样机的行为建模极大的减少了虚拟维修样机与虚拟环境的交互数据量,可以很好的满足虚拟维修仿真实时性的应用要求。     

基于MTN的维修工作建模与仿真技术研究

维修工作过程模型是维修性与维修工作分析与评定的重要基础和手段，现有的建模技术在描述维修过程以及维修过程的相关信息等方面不够直观、也不够丰富。基于Petri网的建模概念，提出了一种用于描述维修工作过程的建模技术——维修工作网（Maintenance Task Net，MTN）；详细叙述了通过维修工作组成元素和维修工作过程关系描述维修工作过程的方法；提出了针对不同维修工作的初始信息进行维修工作建模的两种建模方式；基于该建模技术，开发了软件工具在维修工作分析、虚拟维修仿真中进行了应用研究，验证了MTN的实用性。     

EDMI系统拟实制造软件的研究开发

该文在对ＥＤＭＩ系统ＶＭ问题研究的基础上,提出了以高级语言ＣＶＩ为外壳,以作者开发的优化及无缝连接模块为纽带,将动画仿真软件ＳＩＭＡＮ／ＣＩＮＥＭＡ、ＣＡＤ软件ＰＲＯＴＥＬ和作者开发的ＳＭＴ动画仿真模块集成于一体,构成了ＥＤＭＩ系统数据驱动式的ＶＭ软件,目前已基本完成。     

Virtual machine support for zero‐loss Internet service recovery and upgrade

Software is critical for Internet service availability since an Internet service may become unavailable due to software faults or software maintenance. In this paper, we propose a framework to allow zero‐loss recovery and online maintenance for Internet services. The framework is based on the virtual machine (VM) technology and a connection migration technique called FT‐TCP. It can recover transient application/operating system faults and it allows fault recovery and online maintenance on a single host. The framework substantially enhances FT‐TCP so that it can be run efficiently in the VM environment. Specifically, we propose techniques to reduce the inter‐VM switches and communication. Moreover, we propose service‐specific optimizations to reduce the recovery time of FT‐TCP. Finally, the framework provides an interface for the service designers to implement more service‐specific optimizations. The framework was implemented by modifying an open source VM monitor, Xen, and the Linux kernel running on top of Xen. The effectiveness and efficiency of the framework were evaluated by running two Internet services, WWW proxy and FTP, on the proposed framework and measuring the impact on their performance. According to the experimental results, our approach causes only slight performance overhead (i.e. less than 4%) and memory overhead (i.e. less than 750 KB) for both the services. Copyright © 2007 John Wiley & Sons, Ltd.     

DFA-VMP: An efficient and secure virtual machine placement strategy under cloud environment

The problem of Virtual Machine (VM) placement is critical to the security and efficiency of the cloud infrastructure. Nowadays most research focuses on the influences caused by the deployed VM on the data center load, energy consumption, resource loss, etc. Few works consider the security and privacy issues of the tenant data on the VM. For instance, as the application of virtualization technology, the VM from different tenants may be placed on one physical host. Hence, attackers may steal secrets from other tenants by using the side-channel attack based on the shared physical resources, which will threat the data security of the tenants in the cloud computing. To address the above issues, this paper proposes an efficient and secure VM placement strategy. Firstly, we define the related security and efficiency indices in the cloud computing system. Then, we establish a multi-objective constraint optimization model for the VM placement considering the security and performance of the system, and find resolution towards this model based on the discrete firefly algorithm. The experimental results in OpenStack cloud platform indicates that the above strategy can effectively reduce the possibility of malicious tenants and targeted tenants on the same physical node, and reduce energy consumption and resource loss at the data center.     

Distributed virtual machine consolidation: A systematic mapping study

Background:Virtual Machine (VM) consolidation is an effective technique to improve resource utilization and reduce energy footprint in cloud data centers. It can be implemented in a centralized or a distributed fashion. Distributed VM consolidation approaches are currently gaining popularity because they are often more scalable than their centralized counterparts and they avoid a single point of failure.Objective:To present a comprehensive, unbiased overview of the state-of-the-art on distributed VM consolidation approaches.Method:A Systematic Mapping Study (SMS) of the existing distributed VM consolidation approaches.Results:19 papers on distributed VM consolidation categorized in a variety of ways. The results show that the existing distributed VM consolidation approaches use four types of algorithms, optimize a number of different objectives, and are often evaluated with experiments involving simulations.Conclusion:There is currently an increasing amount of interest on developing and evaluating novel distributed VM consolidation approaches. A number of research gaps exist where the focus of future research may be directed.     

面向云计算的集群文件系统性能对比测试

虚拟机使用集群文件系统是云计算主要架构模式之一,主要分为共享式集群文件系统和分布式集群文件系统两大类.其中,后者是近年来学术界关注的热点,在产业界也逐渐得到深入应用.采用测试法,选取fio作为测试工具,以IOPS作为度量指标,对比两类集群文件系统的性能优劣.实验结果显示,在单物理机节点配置下进行单台虚拟机IOPS写性能测试,共享式文件系统要好于分布式集群文件系统大约40%,但读性能要差1.5倍;对于多台虚拟机并发测试,则当支持虚拟机运行的共享式/分布式集群文件系统规模小于16台时,前者和后者性能基本一致.否则,后者会明显好于前者.     

OpenStack Neat: a framework for dynamic and energy‐efficient consolidation of virtual machines in OpenStack clouds

Dynamic consolidation of virtual machines (VMs) is an efficient approach for improving the utilization of physical resources and reducing energy consumption in cloud data centers. Despite the large volume of research published on this topic, there are very few open‐source software systems implementing dynamic VM consolidation. In this paper, we propose an architecture and open‐source implementation of OpenStack Neat, a framework for dynamic VM consolidation in OpenStack clouds. OpenStack Neat can be configured to use custom VM consolidation algorithms and transparently integrates with existing OpenStack deployments without the necessity of modifying their configuration. In addition, to foster and encourage further research efforts in the area of dynamic VM consolidation, we propose a benchmark suite for evaluating and comparing dynamic VM consolidation algorithms. The proposed benchmark suite comprises OpenStack Neat as the base software framework, a set of real‐world workload traces, performance metrics and evaluation methodology. As an application of the proposed benchmark suite, we conduct an experimental evaluation of OpenStack Neat and several dynamic VM consolidation algorithms on a five‐node testbed, which shows significant benefits of dynamic VM consolidation resulting in up to 33% energy savings. Copyright © 2014 John Wiley & Sons, Ltd.     

Prediction-based proactive load balancing approach through VM migration

The ever-growing intricacy and dynamicity of Cloud Computing Systems has created a need for Proactive Load Balancing which is an effective approach to improve the scalability of today’s Cloud services. In order to manage the load proactively on the Cloud system during application execution, load should be predicted through machine learning approaches and handled through VM migration approaches. Thus, this paper formulates an effort to focus on the research problem of designing a prediction-based approach for facilitating proactive load balancing through the prediction of multiple resource utilization parameters in Cloud. The involvement of this paper is twofold. Firstly, various machine learning approaches have been tested and compared for predicting host overutilization as well as underutilization. Secondly, the load prediction model having maximum accuracy from the tested models has been utilized for implementing the proactive VM migration using multiple resource utilization parameters. Further, the proposed technique has been validated through performance evaluation parameters using CloudSim and Weka toolkits. The simulation results clearly demonstrate that the proposed approach is effective for handling VM migration, reducing SLA Violations, VM migrations, execution mean and standard deviation time.     

具有瀑布特征的可信虚拟平台信任链模型

将虚拟化技术与可信计算相结合构建的可信虚拟平台及其信任链模型是目前的一个研究热点。目前大部分的研究成果采用在虚拟平台上扩展传统信任链的构建方法,不仅模型过粗且逻辑不完全合理,而且还存在底层虚拟化平台和顶层用户虚拟机两条分离的信任链问题。为此,提出一种具有瀑布特征的信任链模型——TVP-QT,该模型以硬件可信平台模块（TPM）为起点,在底层虚拟化平台和顶层用户虚拟机信任链之间加入可信衔接点。当信任链从底层虚拟化平台传递到可信衔接点时,由可信衔接点负责对用户虚拟机的可信虚拟平台模块（vTPM）进行度量,之后将控制权交给vTPM,由vTPM负责对用户虚拟机启动的组件及应用进行度量。该模型中可信衔接点具有承上启下的瀑布特征,能满足虚拟化环境的层次性和动态性特征,保证了整个可信虚拟平台的可信性。不仅从理论上证明了该模型的正确性,而且对实例系统的分析和讨论也表明了该模型的通用性与可行性;在Xen中对该模型进行了仿真实验,实验结果表明该信任链传递理论可以保证可信虚拟化环境在整个运行过程是安全可信的。     

VMStore: Distributed storage system for multiple virtual machines

Desktop virtualization is a very hot concept in both industry and academic communities. Since virtualized desktop system is based on multiple virtual machines (VM), it is necessary to design a distributed storage system to manage the VM images. In this paper, we design a distributed storage system, VMStore, by taking into account three important characteristics: high performance VM snapshot, booting optimization from multiple images and redundancy removal of images data. We adopt a direct index structure of...