基于DAI中间件的异构数据库集成

在研究异构数据库中数据集成的基本原理基础上,提出了数据库集成模型实现策略,即在异构数据库之间构建了一个中间层软件--"虚拟数据库系统",经授权认证的合法用户通过"虚拟数据库系统"提供的标准访问接口及统一数据格式对环境中各种分布的、异构的、不同种类的数据资源进行动态访问和集成.     

轻型的访问频率限制服务模型的设计与实现

为防止开放系统的公共接口被过度调用.本文提出一种面向系统内部的访问频率限制服务轻型模型.并给出泛型键值索引,频率约束算法等关键技术实现.该服务模型抽象了各种业务的访问频率限制逻辑,记录各个键值对特定业务的访问间隔和访问时间,通过频率约束算法,为系统公共接口提供访问频率约束依据.使得公共接口可以对外界请求做出拒绝.消除了因接口过调用而带来的系统安全隐患.提高了系统的服务质量以及接口调用的有效性.     

基于云计算的虚拟计算机实验室设计

本文为了使实验室在资源使用、时空等方面的不足得到解决,设计了基于云计算的虚拟计算机实验室。此方案利用互联网浏览器实现资源预约,根据远程桌面程序对资源进行连接与方案,并且通过服务存储、注册和检索等功能对实验资源进行管理。创建虚拟计算机实验室能够使实验室资源在科研、教学中的应用得到提高。     

一个基于网格资源超市的计算网格资源管理模型

在现有的基于经济模型的网格资源管理方法中,用户共享资源访问一般经由网格用户代理实现,而资源提供者将资源交给网格资源代理处理,网格用户代理通过网格资源经纪访问网格资源代理,获取共享资源信息并使用共享资源。这类方法制约了用户直接选择使用共享资源,也限制了用户共享资源的范围、延长了作业运行周期。文章给出的基于网格资源超市的计算网格资源管理模型、共享资源访问流程及网格资源管理分配策略,较好地解决了这几个问题。     

基于Web服务的校园网格异构数据源统一访问接口

针对OGSA-DAI中间件只面向JDBC的局限性,采用OGSA-DAI的优秀设计思想,提出一个基于Web服务的异构数据源统一访问接口(UDAI)模型,UDAI利用XML Web Service技术跨平台性和ADO.NET增加的数据库访问能力,既保证了接口实现的通用性与易扩展性,又使接口实现了对数据访问、数据库连接、数据格式转换、数据传输、数据库集成等底层细节的屏蔽,满足了用户对网格数据资源的共享访问的需求.     

基于角色访问控制的移动代理安全系统的UML建模

鉴于移动代理的安全机制，文中用统一建模语言(UML)描述了基于角色的访问控制安全模式基于角色的访问控制(RBAC)和移动代理系统的系统结构，利用RBAC控制代理对代理平台资源的访问，得出了若干结论。     

基于虚拟数据库技术的频谱网格数据库访问和集成

随着无线电设备种类和数量的增加,无线电频谱管理在社会生产和生活方面起着越来越重要的作用.但是由于历史及地区发展的不平衡性造成了我国目前各地区的频谱管理系统相对独立,极大的制约了我国频谱管理技术的发展,造成了资源的浪费及不必要的重复建设.在对现有频谱管理系统特点分析的基础上,提出一种在网格环境下的基于虚拟数据库技术的频谱数据库的访问和集成方法,并给出虚拟数据库的构建策略、频谱数据库资源注册和查询映射方法,为资源使用者提供了访问频谱数据库的一致访问接口.     

基于Internet的拨号访问

虚拟专用网络（VPN）使得远程用户可以通过公共分组交换网访问中心LAN的信息,而其安全性和可靠性又等同于通过点对点专用线路访问中心LAN。基于Internet的拨号访问就是指远程用户通过拨通本地ISP来访问中心LAN的信息,其性能等同于直接和中心LAN建立拨号连接,而通信费用又只需支付本地市话费用的这样一种技术。本文讨论了该技术所使用的隧道协议、工作过程和数据安全传送,最后介绍了3Com公司的基于Internet的拨号访问实现方案。     

基于ASP模式下UD_RBAC模型的研究与实现

随着应用服务提供商(ASP)模式的发展,为解决集成了越来越多应用服务的ASP平台与用户之间复杂的管理需求,提出了一种ASP模式下用户授权代理机制的角色访问控制(UD-RBAc)模型.文中对UD_RBAC模型形式化描述,细致地分析了其构成要素、用户授权代理管理模式和实施策略.采用LDAP目录访问协议统一存储用户身份和权限信息,通过代理策略保护应用服务资源,实现对用户的访问进行分级授权和控制.     

基于云的信号处理虚拟实验系统设计

虚拟实验室利用远程真实资源或虚拟设备资源构建实验系统,并通过实验教学资源的集中网络存储及数据库的统一管理来改善资源获取与信息交流方式。文中采用JSP Web,Android应用开发,MySQL数据库等技术设计一个基于云的开放式信号处理虚拟实验系统,实现对现有实验室资源的网络化与虚拟化。该系统采用TCP协议与自定义应用层协议构建内部网络,通过云端服务器管理虚拟实验,使用应用网关监控实验板卡,并通过手机APP,Web浏览器为用户提供交互界面,用户接入网络即可进行实验操作。     

基于网络的电力拖动自动控制系统虚拟实验室建设的探索与实践

电力拖动自动控制系统虚拟实验室．就是利用网络技术在Web中创建出一个可视化的虚拟实验操作环境，通过操作MATLAB中的虚拟实验仪器，可进行各种高速系统的仿真实验。这种虚拟实验室具有一系列优点：首先可以给学生提供丰富的实验资源，解决实物实验室设备少，投资多的问题；其次可以为实际的科研项目和工程提供仿真平台，提高科研的效率和质量；第三是可以在线联接相关的企业和院校的网站，促进基础知识与最新技术的融合。     

用VPN与DMZ技术改造校园网络的研究

为了解决既能在异地访问内网资源,又能充分保证内网资源的高度安全,将VPN与DMZ技术应用于校园网络的升级改造。提出了针对DMZ专区的三类IP地址映射算法与合法外网用户通过VPN访问内网资源需要的虚拟IP地址转换函数,并在此基础上提出了VPN与DMZ技术在校园网上集成应用的解决方案。通过在校园网中合理构建DMZ专区与VPN网络,巧妙设置DMZ与VPN的访问规则,在充分保证校内资源安全的前提下,成功解决了异地用户共享内网资源的难题。     

A DSP-Based Remote Control Laboratory

This paper presents a framework for rapid remote experiment implementation in the field of automatic control. The proposed solution is based on in-house developed embedded control hardware and two commercially available software packages. MATLAB/Simulink is used for rapid experiment control algorithm development, while LabVIEW is used for the user front-end and remote control. A combination of presented hardware and software solutions enables the rapid and easy creation of different interactive remote control experiments. Using this solution, a digital-signal-processor-based remote control laboratory for teaching purposes has been realized. This remote laboratory enables the remote users to easily interact with a set of physical control experiments through the Internet. In the friendly user interface, the remote user can change predefined system parameters and observe system response in textual, graphical, or video format. In addition, this remote laboratory includes a booking system, which enables remote users to book experiments in advance.     

Bandwidth Allocation Strategies in Wide-Band Integrated Networks

A common digital transmission facility in a wide-band integrated service digital network (ISDN) provides shared access to a community of heterogeneous users. Traffic demands from these users vary in their arrival rate, their service time, and their bit rate. In order for this type of communication system to handle its traffic demands with high efficiency and flexibility, a close control of access to the shared bandwidth is required. We model the system by a general multiserver queueing system where customers demand service from a random number of servers. If no waiting is allowed, this queueing model is readily analyzed, and various server allocation strategies can be studied. If the various access requests are queued for service, then the system calls for efficient strategies for allocating servers to waiting customers. In this case, exact analysis of the underlying queueing model becomes quite difficult. For this case, we present some analytic and simulation results of the performance of the system under several server allocation policies.     

Research on service-oriented policy-driven IAAS management

Cloud computing refers to the provision of computational resources on demand via a computer network. It is considered to be the third IT revolution following personal computer revolution and the Internet revolution. IAAS, a kind of service provided by cloud computing, can supply users with the convenience and flexibility of virtual resources to achieve the same power supply as the water supply. Though there are kinds of existing IAAS solutions, but they are all common system architecture design, without taking into account the characteristics of applications resulting in inefficient service provision. In this paper, by referencing service-oriented philosophy IAAS platform is reconstructed. Based on loosely coupled physical resources by virtualization technology, a policy-based management system is provided to optimize service monitoring and service scheduling. Prototype implement show that it will effectively improve the performance of service running on IAAS.     

基于资源调度的远程在线实验室设计

远程在线教育实验室和基于Web的远程学习课程一样迅速地部署在世界各地传统的校园里.本文介绍了远程在线实验室资源调度系统,以用来为地理上分散的多用户协调共享实验室资源,避免用户在时间上的资源冲突,并为不同用户请求提供三种不同优先级处理的功能.     

Tunneling techniques for end-to-end VPNs: generic deployment in an optical testbed environment

Service providers today are constantly seeking to offer multiple services on a single common infrastructure. For instance, it is desirable sometimes to provide transport services transparently to data traffic encapsulated over different network layers. Tunneling is a technique for encapsulating a packet or frame within another packet of the same or a different network layer. One of the motivations for tunneling is bridging various heterogeneous networks that use different protocols for communication. Tunneling is also used for providing private and secure communications over a publicly shared network. This article investigates the interactions between different tunneling technologies in order to provide end-to-end virtual connectivity to end clients. Particularly, the article describes the technical details of the implementation of various layer 2 tunneling techniques - such as L2TP, GRE, and MPLS-based tunnels - in order to establish an end-to-end virtual connection service as a concatenation of services offered by the different network domains along the path between end users.     

Interference management for spectral coexistence in a heterogeneous satellite network

With the advent of the fifth generation of mobile radio communication by 2020, there will be many challenges such as increasing service demand with low delay in providing billions of end users called the satellite mobile users. It is expected that terrestrial communication systems will be faced with a dense network having many small cells anywhere and anytime. Therefore, there are some remote regions in the world where terrestrial systems cannot provide any services to end users. Furthermore, because of lack of spectral resources, it is very important that the spectrum is shared between satellite systems and terrestrial equipment by a suitable solution to interference management. In this paper, a heterogeneous satellite network that includes low earth orbit (LEO) satellite constellation and terrestrial equipment is proposed to provide low delay services. In this type of structure, interference management based on transmission power control between LEO satellite systems and mobile users is very important for obtaining high throughput. Moreover, in order to mitigate interference, transmission power control is shown based on noncooperative Stackelberg game under many subgames through pricing‐based algorithm and convex optimization method. Finally, the simulation results show that the performance of this study's system model will be improved through the proposed algorithm.     

基于LabVIEW的高职电子远程实验开发

本课题应用虚拟仪器技术,采用LabVIEW 9.0作为开发工具,构建了一个适合高职电子专业学生远程使用的实验平台。文中重点讨论了远程实验平台的总体框架、实验项目的开发与集成、实验平台网络通信的实现方法。学生使用浏览器或“连接至远程前面板”方式完成实验。此种模式突破了传统实验的时空限制,对于充分利用教学资源、更大程度地实现资源共享具有重要意义。