Build grid-enabled large-scale collaboration environment in e-Learning grid

As a new branch of grid computing, e-Learning grid is emerging as a nationwide e-Learning infrastructure, which can provide innovative learning experience for learners. In such a grid environment, collaboration services will be the key elements due to the pervasive requirement for cooperative work and collaborative learning. Although there exist enormous research efforts on grid-based collaboration technologies, most of them have many limitations. In this paper, with the findings from the computer support cooperative work (CSCW)/computer support collaborative learning (CSCL) and advantages provided by grid, we propose to build grid-enabled large-scale collaboration environment (GLCE). GLCE focuses on distributed, large-scale, and cross-organizational collaboration through creating group-centered next generation collaboration environment, where both intra-group and inter-group collaboration could be supported. With this idea in mind, we present a grid-based cooperative work framework (GCWF), which aims to implement GLCE with an “upper layer” collaboration middleware based on the special-purpose grid infrastructure designed by our team. The preliminary results of our research on GLCE have been applied to build the learning assessment grid (LAGrid). The goal of LAGrid is to support the formative assessment business in China Radio and TV University (CRTVU) and large-scale collaboration within virtual organization (VO) has been realized.     

Visualizing large-scale human collaboration in Wikipedia

Volunteer-driven large-scale human-to-human collaboration has become common in the Web 2.0 era. Wikipedia is one of the foremost examples of such large-scale collaboration, involving millions of authors writing millions of articles on a wide range of subjects. The collaboration on some popular articles numbers hundreds or even thousands of co-authors. We have analyzed the co-authoring across entire Wikipedias in different languages and have found it to follow a geometric distribution in all the language editions we studied. In order to better understand the distribution of co-author counts across different topics, we have aggregated content by category and visualized it in a form resembling a geographic map. The visualizations produced show that there are significant differences of co-author counts across different topics in all the Wikipedia language editions we visualized. In this article we describe our analysis and visualization method and present the results of applying our method to the English, German, Chinese, Swedish and Danish Wikipedias. We have evaluated our visualization against textual data and found it to be superior in usability, accuracy, speed and user preference.     

A grid-enabled problem solving environment for parallel computational engineering design

This paper describes the development and application of a piece of engineering software that provides a problem solving environment (PSE) capable of launching, and interfacing with, computational jobs executing on remote resources on a computational grid. In particular it is demonstrated how a complex, serial, engineering optimisation code may be efficiently parallelised, grid-enabled and embedded within a PSE. The environment is highly flexible, allowing remote users from different sites to collaborate, and permitting computational tasks to be executed in parallel across multiple grid resources, each of which may be a parallel architecture. A full working prototype has been built and successfully applied to a computationally demanding engineering optimisation problem. This particular problem stems from elastohydrodynamic lubrication and involves optimising the computational model for a lubricant based on the match between simulation results and experimentally observed data.     

基于数据网格技术的可共享e-Learning平台的设计

e-Learning已成为最受欢迎的教学方式之一.SCORM作为最流行的e-Learning标准已被不同的e-Learning平台采用.只要符合SCORM标准的课件就可以被其它e-Learning平台共享.但是大多数的e-Learning平台不能直接在Intemet上共享课件.基于这个问题,采用称为数据网格的网格计算技术,设计了一个可共享的e-Learning平台,可以整合不同的SCORM平台形成一个大型的分布式e-Learning环境.     

Private cloud for collaboration and e-Learning services: from IaaS to SaaS

The idea behind cloud computing is to deliver Infrastructure-, Platform- and Software-as-a-Service (IaaS, PaaS and SaaS) over the Internet on an easy pay-per-use business model. The Hochschule Furtwangen University (HFU) is running their own private cloud infrastructure, called Cloud Infrastructure and Application CloudIA. The targeted users of the CloudIA project are HFU staff and students running e-Learning applications, and external people for collaboration purposes. Therefore, in this paper, we introduce our work in building a private cloud. More specifically, this paper shows how our cloud offerings in each of the cloud service models, i.e. IaaS, PaaS and SaaS, address the requirements and needs of e-Learning and collaboration in an university environment.     

基于网格门户的协同服务集成技术研究

目前的协同服务建立在分布、异构、动态的网格环境中,能否提供一个统一的接口去访问这些资源以达成更广泛的协同变得越来越重要.门户技术所特有的优点为协同应用的集成提供了有效的方法,结合网格技术和门户技术,提出了基于网格门户的协同服务集成技术的设计方案和一个初步的实现.     

网格环境中资源发现机制的研究

随着高性能应用需求的迅猛发展,单台高性能计算机已经不能胜任一些超大规模应用问题的解决。这就需要将地理上分布、系统异构的多种计算资源通过高速网络连接起来,共同解决大型应用问题,从而产生了网格（Grid）。但是在网格这种共享资源的集合中,由于资源共享的广泛性,资源的异构性等等都使得资源发现更具有挑战性。目前存在的一些分布式环境中的资源发现大多是基于集中获分布的,由于集中式资源发现不能很好地满足系统的扩充,而分布式资源发现又会产生大量的网络通讯,因此这两种机制将不可避免地结合在一起,即形成分层式资源发现机制。     

Automatic grid assembly by promoting collaboration in peer-to-peer grids

Currently, most computational grids (systems allowing transparent sharing of computing resources across organizational boundaries) are assembled using human negotiation. This procedure does not scale well, and is too inflexible to allow for large open grids. Peer-to-peer (P2P) grids present an alternative way to build grids with many sites. However, to actually assemble a large grid, peers must have an incentive to provide resources to the system. In this paper we present an incentive mechanism called the Network of Favors, which makes it in the interest of each participating peer to contribute its spare resources. We show through simulations with up to 10,000 peers and experiments with software implementing the mechanism in a deployed system that the Network of Favors promotes collaboration in a simple, robust and scalable fashion. We also discuss experiences of using OurGrid, a grid based on this mechanism.     

支持大规模智能电网的数据存储方法

针对大规模智能电网中的监测数据具有海量性、实时性、动态性等特点,提出一种以数据为中心的支持大规模智能电网的数据存储方法:海量动态数据的分层扩展存储机制。首先,采用扩展哈希编码方法动态增加存储节点,避免突发、频发事件数据的丢失,增强系统的可用性;然后,采用多阈值级别方法将数据分散到多个存储节点上,避免出现存储热点问题,实现负载均衡。实验结果表明,分层扩展存储机制能够最大限度地满足海量数据的存储需求,获得较好的负载均衡,并且使总能耗最低,有效地延长了网络的生命周期。     

网格环境下集群管理系统

分析了集群接入网格的过程中所面临的问题,研究了在网格环境下使用集群的方法,详细分析了集群接入网格需要提供的接口和服务,并实现了一个网格环境下集群管理的原型系统,将集群转化成为一种标准的、透明的资源接入网格.通过该系统用户能够在任何地方使用分布在各处的集群资源,系统能保证用户提交的作业正确、有效的运行,并及时向用户反馈提交作业的相关信息.实验分析表明,该系统能够有效的整合集群计算资源,从而提高计算能力,增大全局吞吐量.     

China's e-science knowledge grid environment

The Internet and World Wide Web are milestones in the history of information sharing. Scientists are increasingly relying on them to support their research. Knowledge is the basis of realizing intelligent services. The knowledge grid is a mechanism that can synthesize knowledge from data through mining and reference methods and enable search engines to make references, answer questions, and draw conclusions from masses of data. The knowledge grid infrastructure supports e-science through a set of relevant application services and semantic resources. We have developed a semantic-link-making tool for users to conveniently describe their understandings of provided resources and background knowledge.     

Dynamic multi-resource advance reservation in grid environment

How to guarantee user’s QoS (Quality of Service) demands become increasingly important in a service-oriented grid environment. Current research on grid resource advance reservation, a well known and effective mechanism to guarantee QoS, fails to adapt to dynamic behavior of grid, and cannot solve imprecise deny of reservation request problem efficiently. For this, enabling system architecture for advance reservation is proposed. Virtual resource container (VRC) is adopted to alleviate a negative effect resulted from dynamic behavior of grid and QoS deviation distance (QDD) based logical resource selection algorithm is put forward to decrease imprecise reject ratio of reservation. At last, this new architecture is deployed to campus grid, and two illustrative experiments are conducted. Experimental results show that system architecture for advance reservation proposed in this paper can alleviate negative influence of grid resource dynamic fluctuation and avoid imprecise reject of advance reservation request effectively.     

基于Hierarchy结构的网格资源发现算法

为了解决传统资源发现机制不能很好地适应网络状态、可扩展性较差等问题,在超级节点模型的基础上,结合联系节点,建立了一种基于层次结构的网格模型,设计了成员加入协议,给出了基于跳数限定、缓存列表的资源发现算法。通过对网络架构的分析,该模型能够适应网格资源的复杂性与异构性,可扩展性好。实验结果证明：该算法缩短了查询时间,提高了网格环境下资源发现的效率。     

网格环境下的G-R-TRBAC访问控制模型

针对网格复杂的访问控制需求,对现有的任务-角色访问控制模型进行改进,建立了角色-任务&角色的网格访问控制（G-R_TRBAC）模型。该模型在网格环境虚拟组织域间使用基于角色的访问控制策略(RBAC)结合证书管理系统,网格环境虚拟组织域内则是经过改进的任务-角色访问控制模型,满足了网格访问控制的多域性和动态性。     

Independent checkpointing in a heterogeneous grid environment

The EU-funded XtreemOS project implements an open-source grid operating system based on Linux. In order to provide fault tolerance and migration for grid applications, it integrates a distributed grid-checkpointing service called XtreemGCP. This service is designed to support various checkpointing protocols and different checkpointer packages (e.g. BLCR, LinuxSSI, OpenVZ, etc.) in a transparent manner through a uniform checkpointer interface. In this paper, we present the integration of a backward error recovery protocol based on independent checkpointing into the XtreemGCP service. The solution we propose is not checkpointer bound and thus can be transparently used on top of any checkpointer package.To evaluate the prototype we run it within a heterogeneous environment composed of single-PC nodes and a Single System Image (SSI) cluster. The experimental results demonstrate the capability of the XtreemGCP service to integrate different checkpointing protocols and independently checkpoint a distributed application within a heterogeneous grid environment. Moreover, the performance evaluation also shows that our solution outperforms the existing coordinated checkpointing protocol in terms of scalability.     

网格环境下的混杂副本管理拓扑结构

在网格中,数据常常由于性能和可用性等原因进行复制.如何有效地管理网格环境中的各副本是网格系统中需要解决的重要问题.提出了一种可扩展及动态自适应的副本管理拓扑结构——混杂网格副本管理拓扑结构（HGRMT）.HGRMT将传统树状的网格逻辑结构中的各节点,在不同层次上又连接成环状,并在此基础上提出了层间与组内不同的副本创建算法.实验表明,HGRMT有较好的可扩展性、可靠性和自适应性.     

Improved occupancy grid mapping in specular environment

This paper addresses the improved method for sonar sensor modeling which reduces the specular reflection uncertainty in the occupancy grid. Such uncertainty reduction is often required in the occupancy grid mapping where the false sensory information can lead to poor performance. Here, a novel algorithm is proposed which is capable of discarding the unreliable sonar sensor information generated due to specular reflection. Further, the inconsistency estimation in sonar measurement has been evaluated and eliminated by fuzzy rules based model. To achieve the grid map with improved accuracy, the sonar information is further updated by using a Bayesian approach. In this paper the approach is experimented for the office environment and the model is used for grid mapping. The experimental results show 6.6% improvement in the global grid map and it is also found that the proposed approach is consuming nearly 16.5% less computation time as compared to the conventional approach of occupancy grid mapping for the indoor environments.     

网格环境下安全认证模型的研究

在分析了当前广泛采用的身份认证机制的基础上,结合网格发展的需要,研究了不同网格环境下GSI方案和 KX.509方案.借鉴 KX.509的代理思想,在 Globus 环境下提出了一种采用 Wen 登陆模块构建的网格身份认证模型,为校园网格用户提供透明的证书生成,使用和管理.用户在注册和认证过程中,Web登陆模块自动为用户产生数字代理证书,使用户无须拥有自己的数字证书.     

基于大规模智能电网网格结构的查询方法

由于智能电网输电线路监测系统的查询多数是针对无线传感器网络(WSN)的全局式查询,不能满足用户基于任意区域的灵活高效的查询需求,根据该系统的网络布局和查询特点,提出了一种基于大规模智能电网网格结构的查询方法MSQuery。MSQuery将不同网格内的查询节点的数据汇聚到一棵或多棵逻辑查询树上, 采用逻辑查询树的合并策略建立优化的回收路径。将MSQuery与采用路线型结构进行查询的RSA算法和采用簇型结构进行查询的SkySensor算法进行对比,结果显示MSQuery的平均传输消耗最小,平均剩余能量最大。实验结果表明,MSQuery可以快速地返回查询窗口内的查询结果,降低通信消耗,节省传感器节点能量。     

校园数据网格环境框架研究

随着因特网和信息系统的快速发展,信息资源迅速膨胀,使得信息集成技术成为目前的研究热点.为了解决目前对校园信息资源缺乏有效管理手段的问题,提出了一个基于数据网格技术的校园数据网格环境框架.该框架利用OGSA-DAI技术,构建了一个层次化的信息集成模型,从而实现了校园信息资源的全面共享和高效整合,解决了信息资源的异构集成、位置透明访问、统一访问接口等问题,并对通过多层次的安全体系,来保证整个校园数据网格的安全.