System software for computer-aided design in electronics on a small machine

A minicomputer installation dedicated to c.a.d. is described. The economy and flexibility of such systems when incorporating comprehensive graphics facilities is stressed. Suitable operating systems are discussed, including an executive program to provide software simulation of three virtual computers (each virtual machine may then run under an independent operating system). Features of the graphical system software are outlined, including device and machine independence, flexibility, ease of use and economy. The applications programming philosophy required is described together with several interactive programs developed for use in electronics design. These programs, used by electronic engineers and research scientists over the past four years, illustrate the flexibility inherent in the system.     

General purpose software for probability computations—A virtual machine approach

The application of probability techniques in structural engineering has seen ample development in the last decade. Yet, the software used for engineering probability computations often lacks generality. The functional needs to be satisfied by general purpose software for engineering applications of probability methods are presented. An analysis of these needs suggests a software design philosophy based on the concept of a software virtual machine for probability computations. The virtual machine architecture and software design are explained. An example problem, in seismic risk analysis, solved with software based on this design is described.     

VMOffset:虚拟机自省中一种语义重构改进方法

虚拟机自省是一种在虚拟机外部获取目标虚拟机信息,并对其运行状态进行监控分析的方法.针对现有虚拟机自省方法在语义重构过程中存在的可移植性差、效率较低的问题,提出了一种语义重构改进方法VMOffset.该方法基于进程结构体成员自身属性制定约束条件,可在不知道目标虚拟机内核版本的情况下,自动获取其进程结构体关键成员偏移量,所得偏移量可提供给开源或自主研发的虚拟机自省工具完成语义重构.在KVM（kernel-based virtual machine）虚拟化平台上实现了VMOffset原型系统,并基于不同内核版本操作系统的虚拟机,对VMOffset的有效性及性能进行实验分析.结果表明：VMOffset可自动完成各目标虚拟机中进程级语义的重构过程,具有可移植性与安全性,且仅对目标虚拟机的启动阶段引入0.05%之内的性能损耗.     

A real-time virtual machine implementation for small microcontrollers

A way to host a full general purpose virtual machine (VM) interpreter on a very small microcontroller platform is described. This machine provides a comprehensive set of general and enhanced functionality efficiently by abstracting the VM instruction set. Measurements were made on the execution of software programs in the virtual machine while running on the target platform in order to demonstrate the machine??s capabilities. Additionally, multitasking capabilities were added to the baseline and found to perform efficiently within the VM. The results proved to be satisfactory and demonstrate that a robust virtual machine can be made available for very small embedded platforms based on simple microcontrollers, such as those that are widely found in aerospace applications.     

一种简单高级语言编译器的设计

在编译原理和虚拟机技术的基础上,采用一种高级语言设计了一个简单的编译器。通过词法分析、语法分析和中间代码、虚拟机等进程,将源程序编译成目标程序,实现了复杂编译器的简单设计。     

基于虚拟仪器技术的智能化充磁机的设计

采用数据采集器LabJack U12在LabVIEW平台上设计了一种基于虚拟仪器技术的新型智能化充磁机,给出了设备的硬件结构、软件模块及虚拟面板的设计方法,对传统的充磁机用最新的计算机软件技术进行技术提升,在有限的基本硬件支持下,完成对数据的采集、分析处理,在计算机屏幕上建立图形化的虚拟面板来实现控制与显示,使其操作简单,自动定量充磁,在线显示充磁过程和充磁产品磁特性参数的功能,具有较广阔的工程应用前景.     

MECOM: Live migration of virtual machines by adaptively compressing memory pages

Live migration of virtual machines has been a powerful tool to facilitate system maintenance, load balancing, fault tolerance, and power-saving, especially in clusters or data centers. Although pre-copy is extensively used to migrate memory data of virtual machines, it cannot provide quick migration with low network overhead but leads to large performance degradation of virtual machine services due to the great amount of transferred data during migration. To solve the problem, this paper presents the design and implementation of a novel memory-compression-based VM migration approach (MECOM for short) that uses memory compression to provide fast, stable virtual machine migration, while guaranteeing the virtual machine services to be slightly affected. Based on memory page characteristics, we design an adaptive zero-aware compression algorithm for balancing the performance and the cost of virtual machine migration. Using the proposed scheme pages are rapidly compressed in batches on the source and exactly recovered on the target. Experimental results demonstrate that compared with Xen, our system can significantly reduce downtime, total migration time, and total transferred data by 27.1%, 32%, and 68.8% respectively.     

基于虚拟机的软件保护研究与设计

虚拟机技术一直是当今计算机安全领域研究的热点之一。从软件保护的角度出发,介绍了基于虚拟机的软件保护设计方案中的关键技术,并给出了一个范例,说明具体步骤和方法。该方法将保护对象细化为函数,给出了单函数识别的具体步骤和方法,利用基本的x86编码来构造虚拟机,对基本指令集采用基于字节码的加解密技术,此外还对各类指令进行了必要的模块化扩展以增加保护力度。目前国内对于虚拟机的保护技术处于起步阶段,因而对于虚拟机技术的理论基础研究和技术实践应用均具有较高的研究价值和发展空间。     

基于虚拟机技术的DCS仿真系统设计与实现

提出了基于虚拟机技术的DCS仿真系统的实现方式,描述了虚拟控制器的具体实现方法及虚拟机技术的其他应用.     

一种云计算环境下的虚拟机动态迁移策略

提出一种云计算环境下的虚拟机动态迁移策略DMS-VM(Dynamic Migration Strategy for Virtual Machine) 。首先,假设了一种云计算环境下虚拟机迁移场景,在该场景下多种应用服务请求处于动态变化之中,并且提供的应用服务与虚拟机是一对一绑定的;其次,提出了该场景下的基于多约束的多目标规划模型,并设计遗传算法作为虚拟机的主要迁移策略;最后利用某个企业的大数据中心作为云端测试环境, 对比测试DMS-VM算法与已有的虚拟机迁移算法的性能。实验结果表明,DMS-VM迁移策略能够更好的减少物理主机的使用数量和虚拟机的迁移次数,同时降低数据中心能耗,性能优于已有的迁移策略。     

基于面向对象的虚拟数控系统的研究

提出了虚拟数控机床的基本系统结构,引入面向对象程序设计的基本概念于虚拟数控机床的设计.根据数控机床各零部件在加工过程中的特点,把它们分成静态类、运动类和动态类3类.在此基础上,利用3维实体CAD（computer aided design）软件系统进行虚拟数控机床加工过程中非变形物体（静态类与运动类）的外形设计并转换成STL（stereolithography）文件,对动态变形物体采用特征造型方法,与设计的成员函数即该零部件的运动函数有机地集成起来,构成类,最终实现数控机床各机构的动态仿真.引入了四元数的基本概念,并将其应用于系统设计与实现.上述方法为虚拟数控系统的研究提供了基本框架.实验结果证明,上述方法是可行的,具有很好的实用价值和参考价值.     

An environment for painless MIMD system development

An environment that lets system applications be expressed as virtual machines, through which architecture-independent multiple-instruction, multiple-data stream (MIMD) programs are written, is described. The virtual machine hides the hardware configuration from the programmer so that the MIMD programming environment always appears the same, regardless of the actual hardware. The data-definition and procedural high-level languages used in the environment and the generation of object code in the environment are discussed. The runtime configuration of the system and an implemented prototype of the system are described     

可裁剪式虚拟机可移植层的研究与开发

针对物联网嵌入式底层设备的设计要求,提出了可裁剪式虚拟机可移植层模型及设计方法,阐述了可移植层中的网络、线程、内存等模块的实现方式及该虚拟机的实例访问。通过可移植层设计,该虚拟机可以在不同硬件平台及操作系统上移植。另外,该虚拟机可以实现动态配置、控制、执行等功能,且具有裁剪性。测试表明,该虚拟机的CPU占有率小,内存损耗低,组件重用率高,裁剪性好,并成功运用于工业现场。     

User centred design for a digital welding machine

The design of the user interface of a digital welding machine based on a user centred design process is described in this paper. Due to the iterative design process and the involvement of end users, interaction techniques have been designed which are optimised for the mental work model of the target user groups.     

雷达回波记录与重演设备中的PCI目标接口控制器

在雷达回波记录与重演设备中，采用132MB、33MHz的PCI局部总线可以实现高速数据传输．而PCI总线接口控制器的设计是雷达回波记录与重演中的关键。本文对雷达回波记录与重演设备中的PCI总线目标接口控制器的逻辑功能及其状态机进行了比较细致的描述，利用max plus Ⅱ实现了PCI目标接口控制器的功能仿真．并得到了仿真时序图。该仿真对于实际接口的设计与实现具有一定参考价值。     

虚拟运行环境描述管理工具的研究和实现

针对分布式网络环境中虚拟运行环境的描述、部署和管理问题,设计和实现了一个图形化的虚拟运行环境的描述、部署和管理系统,该系统整合虚拟机技术,通过图形化的方式来描述目标虚拟运行环境的网络拓扑,配置和部署环境中的虚拟机,并提供了对其中虚拟机基本的管理和控制功能.具有通用性、高可扩展性和灵活性的特点.可用于网格以及其它分布式系统.     

The virtual wind tunnel

The design and implementation of a virtual environment linked to a graphics workstation for the visualization of complex fluid flows are described. The system user wears a stereo head-tracked display, which effectively displays 3-D information, and an instrumented glove to intuitively position flow-visualization tools. The visualization structures and their interfaces in the virtual environment and the implementation hardware and software are described. The performance of the virtual wind tunnel is reviewed using the flow past a tapered cylinder as an example. Performance issues and future directions for the system are discussed     

基于指令相对吞吐率的虚拟机检测方法

对于常见的虚拟机检测方法仅适用于特定配置的虚拟机的不足,设计并实现一种基于特权指令与非特权指令的相对吞吐率变化的检测虚拟机的方法,检测过程采用查询-验证的方式。该方法可以成功地分辨出物理机环境与虚拟机环境的不同,并且事先只需了解较少的待检测目标的配置信息,对不同硬件配置的依赖性较小。