云计算资源池容灾中心建设解决方案研究

介绍了容灾等级的选择、主流容灾技术,明确了容灾中心的建设方向和思路。同时,提出了多个解决方案,为云计算容灾中心的具体建设工作提供了重要参考。     

信息系统容灾建设初探

初步探讨信息系统容灾定义、容灾技术、灾备中心建设、以及容灾的关键指标,阐述了信息系统容灾的重要性。     

政企行业容灾系统解决方案

对政企客户容灾系统建设的意义及方针进行了总结,对信息系统灾难恢复规范标准的六级体系进行了概括,对容灾系统建设的方法论及由此衍生的系统实施步骤进行了阐述;针对国标的六级灾备体系,提出了不同容灾级别实现的技术方案,并对技术方案中的关键技术进行了分析;最后对政企客户的容灾系统的建设提出了建议。     

商业银行容灾系统建设方案

根据商业银行对容灾中心的定位描述,容灾系统不仅具有基本的容灾功能,而且是连接生产核心系统与辅助系统的桥梁．因此,建设容灾系统具有十分重要的现实意义．鉴于容灾系统建设是一个涉及面广、专业性强的系统工程,本文对容灾系统建设的总体原则和思路进行了研究,探讨各种容灾可用技术,并进行分析对比,提出了系统构架,对商业银行容灾系统的建设具有参考价值．     

新农合信息系统数据备份与容灾设计

探讨了如何有效增强新农合信息系统数据的安全性,确保业务系统的连续性。利用数据备份与数据容灾技术,并以"整体规划、分步实施、逐年投入"的建设思路来构建新农合信息系统数据备份与容灾系统。详述了新农合信息系统数据备份与容灾系统的三个建设阶段内容,即本地数据备份系统建设、异地数据级容灾建设、应用级容灾建设,并分阶段实施,以确保建成一个有效的、全面的数据备份与容灾系统。     

用Oracle 9i dataguard构建系统容灾

在信息化建设的过程中,面对系统数据安全要求和应用需求同时要得到满足的情况下,如何做到容灾与应用两不误并增加数据复用率是一个值得研究的问题。提出了用Oracle9i数据库自带功能进行数据复制的数据存储容灾技术,根据不同的实际情况给出了不同数据保护模式和数据容灾模式的建议,并给出了构建数据存储应用的思路和注意点。     

航天测控系统远程数据容灾方案设计与验证

航天测控系统中的重要资产数据对航天任务的成败有重要影响,必须建立数据容灾系统以保障关键数据的安全。分析了当前航天测控系统关键资产数据采用的备份方式及容灾的要求,基于Oracle数据库的远程复制功能研究了航天测控系统远程数据容灾技术,设计了航天测控系统远程数据容灾方案,并搭建模拟实验环境对方案进行了实验测试。实验结果表明,容灾方案能够达到第五级的容灾级别,满足可恢复性、可靠性和实时性指标要求,实现对航天测控系统关键资产数据的远程容灾。     

现代容灾系统及技术

该文归纳总结了现有容灾系统的体系结构,并在此基础上阐述了容灾系统所使用的技术。具体讨论了本地容灾、数据容灾、网络容灾、服务容灾技术的工作原理及各自特点,并重点阐述了数据备份技术。     

基于数据容灾系统的服务漂移实现

传统的数据容灾技术只能提供数据的实时备份与恢复,无法保证服务的连续性.服务容灾技术可以在服务级别上保证业务连续性和数据一致性,但系统设计往往过于复杂.一种基于传统数据容灾系统的服务漂移方案可以有效地解决该问题.该方案在客户服务器出现故障后,使用另一台拥有相同服务配置的镜像服务器,通过iSCSI协议和存储服务器上的逻辑卷镜像建立链接,并基于此虚拟逻辑卷继续提供服务.待客户服务器故障修复后,再切换回本服务器提供服务.这种方案可以使传统的数据容灾系统实现服务级容灾,进一步提高企业关键业务的容灾能力.     

浅析中小企业数据容灾理论和技术

文中系统地分析了企业数据容灾的理论和技术。介绍建立一个容灾备份系统,首先要了解容灾备份的等级要求和评价指标,其次要了解其具体实现技术。最后对容灾系统的关键技术进行了分析和讨论。     

Virtual Triangulation Sensor Development, Behavior Simulation and CAR Integration Applied to Robotic Arc-Welding

Background: An increasing number of industrial robots are being programmed using CAR (Computer Aided Robotics). Sensor guidance offers a means of coping with frequent product changes in manufacturing systems. However, sensors increase the uncertainty and to preserve system robustness, a tool is needed that makes it possible to understand a sensor guided robot system before and during its actual operation in real life.Scope: A virtual sensor is developed and integrated in a CAR hosted environment. The real sensor is of a type commonly used in the arc-welding industry and uses a triangulation method for depth measurements. The sensor is validated both statically and dynamically by matching it with a real sensor through measurements in setups and by comparing a welding application performed in a real and a virtual work-cell created with a CAR application. The experimental results successfully validates its performance. In this context, a virtual sensor is a software model of a physical sensor with similar characteristics, using geometrical and/or process specific data from a computerized model of a real work-cell.     

Theorem Proving Guided Development of Formal Assertions in a Resource-Constrained Scheduler for High-Level Synthesis

This paper presents a formal specification and a proof of correctness for the widely-used Force-Directed List Scheduling (FDLS) algorithm for resource-constrained scheduling of data flow graphs in high-level synthesis systems. The proof effort is conducted using a higher-order logic theorem prover. During the proof effort many interesting properties of the FDLS algorithm are discovered. These properties are formally stated and proved in a higher-order logic theorem proving environment. These properties constitute a detailed set of formal assertions and invariants that should hold at various steps in the FDLS algorithm. They are then inserted as programming assertions in the implementation of the FDLS algorithm in a production-strength high-level synthesis system. When turned on, the programming assertions (1) certify whether a specific run of the FDLS algorithm produced correct schedules and, (2) in the event of failure, help discover and isolate programming errors in the FDLS implementation.We present a detailed example and several experiments to demonstrate the effectiveness of these assertions in discovering and isolating errors. Based on this experience, we discuss the role of the formal theorem proving exercise in developing a useful set of assertions for embedding in the scheduler code and argue that in the absence of such a formal proof checking effort, discovering such a useful set of assertions would have been an arduous if not impossible task.     

A simulation-based heuristic algorithm for disposition of direction finders

A direction finder is a military weapon that is used to find locations of targets that emit radio frequencies. Multiple direction finders are used in a direction finder system for finding locations of targets in an area of interest. We present a two-stage heuristic algorithm for disposing direction finders in a direction finder system for the objective of maximizing the accuracy of estimation of the location of a target that is assumed to be located in the area of interest. In the suggested heuristic algorithm, a simulation-based method is used for estimating the probability of coverage, the probability that a target is in a given region (of a given size) surrounding the estimated location of the target, and another simulation-based method and a local search method are used to determine locations of direction finders that result in the maximum probability of coverage. Performance of the suggested algorithm is evaluated through computational experiments and results show that the algorithm gives a good disposition plan in a reasonable amount of computation time.     

A hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality environment

This article proposes a hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality (VR) environment. The data model integrates a high level constraint-based model for intuitive and precise manipulation, a middle level solid model for complete and precise representation and a low-level polygon mesh model for real-time interactions and visualization in a VR environment. The solid model is based on a hybrid B-rep/CSG data structure. Constraints are embedded in the solid model and are organized at hierarchical levels as feature constraints among internal feature elements, part constraints among internal features and assembly constraints between individual parts. In addition to providing a complete and precise model representation and the support for real-time visualization, the proposed data model permits intuitive and precise interaction through constraint-based manipulations for solid modeling in a VR environment. This is a critical issue for product design in a VR environment due to the limited resolutions of today's VR input and output devices.     

The User-Oriented Bengali Easy Orthography

A work on user-oriented Bengali orthography has been carried out while teaching Bengali as a Third language. Learning Bengali is difficult because of the presence of innumerable conjunct letters and the absence of a vowel-sign for the first vowel in Bengali orthography. It is extra difficult for foreigners because the working memory in learning a foreign language is quite limited. It is easy to make a computer-key-board with a thousand letters and signs, but it is difficult to use in practice. It is shown in this work that the Bengali conjunct letters not used as initial letters in word-making were redundant in its orthography and could be dissected to their components, if a missing-letter sign for the unborn first Bengali vowel-sign was raised in accordance with Bengali orthographic rule. Only 30 conjunct letters used in Bengali as initial letters in word-making which could be kept intact. Thus only 108 signs on a key-board, including 10 digits and 20 punctuation and other signs were sufficient in case of a user-oriented Bengali orthography. This revised version was published online in July 2006 with corrections to the Cover Date.     

The User-Oriented Bengali Easy Orthography

A work on user-oriented Bengali orthography has been carried out while teaching Bengali as a Third language. Learning Bengali is difficult because of the presence of innumerable conjunct letters and the absence of a vowel-sign for the first vowel in Bengali orthography. It is extra difficult for foreigners because the working memory in learning a foreign language is quite limited. It is easy to make a computer-key-board with a thousand letters and signs, but it is difficult to use in practice. It is shown in this work that the Bengali conjunct letters not used as initial letters in word-making were redundant in its orthography and could be dissected to their components, if a missing-letter sign for the unborn first Bengali vowel-sign was raised in accordance with Bengali orthographic rule. Only 30 conjunct letters used in Bengali as initial letters in word-making which could be kept intact. Thus only 108 signs on a key-board, including 10 digits and 20 punctuation and other signs were sufficient in case of a user-oriented Bengali orthography. This revised version was published online in July 2006 with corrections to the Cover Date.     

A three-dimensional measurement system for robot applications

This paper presents a 3D noncontacting sensor system designed to measure the position and orientation of a robot end effector. This measurement system includes two parts: a tridimensional object including four spheres placed along the axes of a tetrahedron and a set of three orthogonally pointed cameras. The purpose is to design a measurement system characterized by easy relationships in order to satisfy real-time constraints. The system has been used in two experiments: first, to calibrate a parallel robot and validate the geometrical control performance, then as an exteroceptive sensor in an assembly task. The system computes position and orientation of the tetrahedron in 100 ms time. The position and orientation accuracy are, respectively, 0.6 mm and 0.2 deg in a workspace, being a cube with 0.3 m sides.     

关于一种网格运行时结构的若干注记

进程是传统计算机系统的一个核心概念，自1960年出现以来一直沿用至今，进程的一个主要目的是为主体提供一种运行时结构，在操作系统和处理器硬件支持下，代表主体访问和使用各种资源，与传统的单机和并行机计算平台相比，网格计算机中进程所对应的概念面临新的挑战，包括网格资源繁杂、自主控制的条件下的单一系统映像和资源的共享与协同、与特定操作系统的松耦合、时间和空间的流动性、更高级的交互性，提出一种称为网程(grip)的运行时结构，试图解决上述问题，网程运行在网格操作系统之上，代表网格主体，访问和使用网格资源。     

Reinterpretable Imager: Towards Variable Post‐Capture Space,Angle and Time Resolution in Photography

We describe a novel multiplexing approach to achieve tradeoffs in space, angle and time resolution in photography. We explore the problem of mapping useful subsets of time‐varying 4D lightfields in a single snapshot. Our design is based on using a dynamic mask in the aperture and a static mask close to the sensor. The key idea is to exploit scene‐specific redundancy along spatial, angular and temporal dimensions and to provide a programmable or variable resolution tradeoff among these dimensions. This allows a user to reinterpret the single captured photo as either a high spatial resolution image, a refocusable image stack or a video for different parts of the scene in post‐processing. A lightfield camera or a video camera forces a‐priori choice in space‐angle‐time resolution. We demonstrate a single prototype which provides flexible post‐capture abilities not possible using either a single‐shot lightfield camera or a multi‐frame video camera. We show several novel results including digital refocusing on objects moving in depth and capturing multiple facial expressions in a single photo.     

A dialectical based model coherent with inventive and optimization problems

In an array of problem solving methods, one can traditionally distinguish two kinds of problems: one is a problem that has solutions in a search space and the other is a problem that does not have solutions in a given space. The later problem so called solutionless problem or inventive problem requires an inventive approach to reformulate the problem and dialectical thinking brings benefits in the process. The framework used to formulate problems in a dialectical approach is contradiction. Identification of contradictions plays an important role in distinguishing solutionless problems: a contradiction exists when no solution can be found, and a solution exists when no contradiction can be found. In this article, the inadequacy of existing frameworks in satisfying this requirement is demonstrated and a framework that fits this requirement is proposed.