一种新的虚拟专用网络在全球信息栅格中的应用

为了实现全球范围内的信息资源共享,美军提出了全球信息栅格(Global Information Grid,GIG),在此基础上,基于GIG的虚拟专用网络(Virtual Private Network,VPN)技术也得到了发展和应用;虚拟专用网络技术在战术级网络和作战单元之间实现了互通,并且,GIG虚拟专用网络技术的可测量性,使GIG得以从服务供应网络拓扑中分离出来;文章首先介绍了2547双重虚拟专用网络的操作,并且研究了它在GIG网络技术中的几种应用情况;其次提出了几种2547双重虚拟专用网络体系结构及其可选取性;研究表明,在大规模IP网络中,2547双重虚拟专用网络的作用十分明显。     

基于GIG应用的服务质量体系结构研究

针对网络中不同服务质量体系结构以及它们在GIG(Global Information Grid)网络技术中的应用;首先分析了现有网络中的服务质量体系结构,通过比较不同的服务质量结构在GIG网络技术中的应用,提出了详细的分析结果;其次,对GIG中的三种网络组成部分,MANET、卫星网络和GIG带宽扩展,以及与之相对应的服务质量体系结构进行了正确的评估;最后,通过分析它们之间的相互影响,提出了基于GIG的端对端的服务质量体系结构;深入研究全球信息栅格服务质量体系结构技术对于提高我军信息化建设水平,推进以信息技术革命为主体的新军事革命,具有十分重要的意义。     

ISCSI协议的性能研究

ISCSI是基于IP的网络存储协议中最引人注目的技术之一,它将SCSI协议映射到TCP/IP协议上,使得SCSI命令和数据可以在传统的IP网络上传输,基于通用的IP网络是iSCSI最显著的优点.通过介绍iSCSI协议体系结构和功能实现流程,并对ISCSI协议进行仿真,在对仿真结果分析的基础上,得出结论ISCSI适合在高带宽网络环境下传输大量块数据,且网络带宽对ISCSI协议性能的影响会随着带宽的增加而减小.     

基于GIG边缘网络接口体系结构研究

1999年,美国国防部提出了建设全球信息栅格(Global Information Grid,GIG)的设想,其目的是将美军分布在全球的计算机、传感器网和作战平台网组成一个大系统,实现全球范围内时域和空域的一致以及各分系统的协同,保证在未来战场上将正确的信息、以正确的时间和正确的格式传送到正确的指战员;在支持网络体系结构和协议服务中,功能强大和性能稳定的GIG网络技术发挥着重要的作用;首先,描述GIG边缘网络结构的设计,实现了边缘网络和GIG的无缝链接,其次,体系结构定义了GIG边缘网络、军事网络、政府网络、信息管理系统以及它们之间应用的网关,最后,阐述了网关进入边缘网络中的寻址、路由器选择、信息确认、端对端服务质量和网络服务等性能。     

全球信息栅格服务质量互通性研究

全球信息栅格(Global Information Grid,GIG)是一种大而复杂的网络系统,目的是把美军分布在全球的信息系统、服务和应用结合在一起,形成一种无缝隙、可靠的安全网络;首先,对GIG网络体系结构传输部分进行了概述;其次,描述了网络与网络链接接口、以及在GIG网络应用中,对不同服务质量解决方案进行了归类;最后,讨论了网络交互领域与不同服务质量解决方案之间所面临的挑战。     

基于IP组播技术的视频传输系统的设计与实现

随着压缩视频通信技术和网络技术迅速发展,基于组播技术的视频传输和服务应用日益广泛;在IP网上构建了基于IP组播技术的视频传输系统,视频编码遵循H.263建议,重点研究了压缩视频流在IP网络上可靠传输的通信控制协议和机制实现,并且在嵌入式unux和WINDOWS环境下成功实现了整个系统;本系统成功地用于实验楼安全监控系统中,运行可靠.     

IP网络中高可靠性视频监控的组播设计

视频监控做为安全防范的一个重要手段已应用于各行各业,随着对视频监控的需求不断增加,传统的模拟视频监控技术已不能满足于人们对于图像质量高清、部署灵活、传输占用带宽小等应用的需求,逐渐转向基于IP承载网络的数字监控技术。那么如何使视频监控在IP网络中传输更稳定、可靠?本文将着重阐述如何基于组播技术规划、设计IP网络以满足在大型网络中视频监控的需求。     

基于集成服务的IP网络QoS实现技术

讨论了基于集成服务的IP网络中为实时业务预留资源的方法 ,利用RTP/RTCP实现实时业务传输的有效控制机制 ,以及利用IP数据分组头中的优先级及IPv6头中的流标记信息 ,为实时业务获得优先服务和快速转发的方法 ,实现实时业务在IP网络中传输的QoS。     

网络控制系统Web服务器服务质量管理方案的研究

提出一种基于Web的自适应内容传输管理方案,为不同网络客户提供不同优先级的性能服务,并且各种服务相互独立,同时能基于请求率和传输带宽共享系统资源。这种方案在传统的允入控制基础上改善了服务性能,根据网络负载情况和服务质量需求自适应选择传输内容,满足了客户对网络传输服务质量需求。该管理方案可以在三层模型的中间层实施,便于修改和维护,给出的实验结果显示了该方案的有效性。     

基于主动网络的RSVP体系结构设计

IP网络新的应用对网络的服务质量(QoS)提出了新的不同的要求,因此必须在现有的“尽力服务”机制的基础上提供服务质量管理机制。在对QoS进行分析的基础上,提出了一种新的QoS体系结构,即基于主动网络的QoS体系结构,并结合IntServ QoS模型,提出了支持RSVP协议动态部署的主动节点的模型。     

A Simple Optimal Solution for the Temporal Precedence Problem on Pure Pointer Machines

In this paper we propose an optimal solution to the Temporal Precedence problem—i.e., the problem of managing the dynamic insertion of elements in a collection and the ability to determine, given two elements, which one has been inserted first. The problem is studied on pure pointer machines, i.e., pointer machines with no arithmetic capabilities. We provide an optimal solution (i.e., O(lg lg n) worst case time per operation, if n is the number of insertions) for this problem that is considerably simpler than the solutions previously presented in the literature. We also show how the solution can be improved to allow worst case O(1) insertions and linear space complexity.     

全球信息栅格与服务计算

在探索全球信息栅格的概念及其组成的基础上,研究了服务计算的概念、原则及其不同于面向对象计算的方面,服务计算在全球信息栅格中的应用方式以及如何与传统技术相结合的问题。最后,提出了服务计算应用于全球信息栅格有待解决的问题。     

全球信息栅格仿真技术研究

讨论了全球信息栅格的前沿问题,总结了全球信息栅格的仿真平台的目的、基本情况和主要技术手段,给出目前美国采用的全球信息栅格的基础性拓扑结构.     

Design,implementation, and evaluation of a Programmable Bandwidth Aggregation System for home networks

Bandwidth aggregation is a promising technology that can speed up access to the Internet by bandwidth sharing and multi-path communication. Current Bandwidth Aggregation Systems (BASs) deployed in public networks provide limited performance and flexibility when they are directly used in home networking environments. To reap the full performance benefits of BASs in home networks, they need to be easily and dynamically programmable by home network users. We present the design and implementation of a Programmable Bandwidth Aggregation System (PBAS) that can provide home network users improved performance when sharing bandwidth for activities that access the Internet. We also present an empirical performance evaluation of the system and we demonstrate the superior efficiency of our proposed PBAS over a traditional BAS in terms of computational overheads, loadable code, throughput performance, and programmability.     

Design parameterization and tool integration for CAD-based mechanism optimization

This paper presents an open and integrated tool environment that enables engineers to effectively search, in a CAD solid model form, for a mechanism design with optimal kinematic and dynamic performance. In order to demonstrate the feasibility of such an environment, design parameterization that supports capturing design intents in product solid models must be available, and advanced modeling, simulation, and optimization technologies implemented in engineering software tools must be incorporated. In this paper, the design parameterization capabilities developed previously have been applied to support design optimization of engineering products, including a High Mobility Multi-purpose Wheeled Vehicle (HMMWV). In the proposed environment, Pro/ENGINEER and SolidWorks are supported for product model representation, DADS (Dynamic Analysis and Design System) is employed for dynamic simulation of mechanical systems including ground vehicles, and DOT (Design Optimization Tool) is included for a batch mode design optimization. In addition to the commercial tools, a number of software modules have been implemented to support the integration; e.g., interface modules for data retrieval, and model update modules for updating CAD and simulation models in accordance with design changes. Note that in this research, the overall finite difference method has been adopted to support design sensitivity analysis.     

Ultra-low-power components for an RFID Tag with physical and chemical sensors

In this work the development and optimization of the main components for a multisensing flexible Tag with RFID communication capabilities and integrated physical and chemical sensors for logistic datalogging applications will be reported. For this specific scenario, several constraints must be considered: power consumption must be limited for long-term operation, reliable ISO compliant RFID communication must be implemented, and special encapsulation issues must be faced for reliable sensor integration. In this work, the developments on application specific electronic interfaces and on ultra-low-power Metal OXdide semiconductor (MOX) gas sensors will be reported. The electronics for sensor control and readout as well as for RFID communication are based on an ultra-low-power MSP430 microcontroller from Texas Instruments together with a custom RFID front-end based on analog circuitry and a CPLD digital device, and are designed to guarantee a passive ISO15693 compliant RFID communication in a range up to 6 cm. A thin film battery for sensor operation is included, thus data acquisition and storage can be accomplished when no reader field is present. This design allows the user to access both the traceability and sensor information even when the on-board battery is exhausted. The physical sensors for light, temperature and humidity are commercially available devices, while for chemical gas sensing innovative MOX sensors are developed, based on ultra-low-power micromachined hotplate arrays specifically designed for flexible Tag integration purposes. A single MOX sensor requires only 8.9 mW for continuous operation, while temperature modulation and discontinuous sensor operation modes are implemented to further reduce the overall power consumption. The development of the custom control and RFID front-end electronics, together with innovative ultra-low-power MOX sensor arrays with flexible circuit encapsulation techniques will be described.     

Dual ceiling protocol for real-time synchronization under preemption threshold scheduling

The application of object-oriented design methods to real-time embedded systems is seriously hindered by the lack of existing real-time scheduling techniques that can be seamlessly integrated into these methods. Preemption threshold scheduling (PTS) enables a scalable real-time system design and thus has been suggested as a solution to this problem. However, direct adoption of PTS may lead to long priority inversion since object-oriented real-time systems require synchronization considerations in order to maintain consistent object states. In this paper, we propose the dual ceiling protocol (DCP) in order to solve this problem. While DCP exploits both priority ceilings and preemption threshold ceilings, this is not a straightforward integration of existing real-time synchronization protocols for PTS. We present the rationale for the locking conditions of DCP and show that it leads to the least blocking and response times by comparison with other real-time synchronization protocols. We also present its blocking properties and schedulability analyses. We implemented PTS and DCP in a real-time object-oriented CASE tool and present the associated experimental results, which show that the proposed protocol is a viable solution that is superior to other real-time synchronization protocols for PTS.