Gnutella协议的跨层优化研究与设计

最近几年来,越来越多的P2P系统应用于传统的网络来实现大规模的文件分享.这些平台大多有如下特点:完全分布式、自组织、自恢复,这使得在移动Ad-hoc网络中也逐渐出现相关的应用.然而,传统的协议栈采用的是分层式结构,由于移动Ad-hoc网络高度动态性等特点影响这些协议的性能,这种结构在该网络中效率低下.文中通过对移动Ad-hoc环境下的Gnutella协议的性能的各方面分析与研究,发现Gnutella协议直接用于该环境并不理想.因此,提出了一种跨层接口的优化机制,实现网络层的TBRPF路由协议与应用层的Gnutella协议实现有效信息的互通.最后,通过模拟实验说明比预想的性能要好,适合自组织及自恢复的Ad-hoc网络.     

Gnutella环境下基于节点逻辑度的资源定位方法

在Gnutella网络中如何进行资源定位是提高网络效率、增强网络可扩展性的重要问题.在已有研究的基础上提出一种基于节点逻辑度的资源定位方法,加入节点基于当前Gnutella网络中节点的逻辑度选择要建立链接的节点,请求节点通过所构建的逻辑结构来定位资源.仿真实验结果表明该方法能有效地降低Gnutella网络的通信负载,减少冗余消息,提高Gnutella网络的可扩展性.     

数据摆渡在安全移动存储中的应用研究

当前针对移动存储设备的信息安全防护需求非常迫切,防止移动设备中的隐秘信息泄露问题尤其突出。采用可信网络接入（TNC）架构,基于数据摆渡技术实现对移动存储设备的可信域接入认证和数据文件在移动存储设备中的无协议摆渡,同时加入基于指纹识别的身份认证和用户对单个文件的操作授权机制来进一步提高移动存储的整体安全性。     

基于Gnutella的P2P电子商务模型需求与设计

Gnutella是完全分布式的非结构化的P2P网络,与其他类型的P2P网络相比,它容错性好,支持复杂的查询,并受节点频繁加入和退出系统的影响小,在Gnutella网络上的电子商务应用有着良好的研究前景.本文就通过对P2P通信方式与基于Gnutella协议的网络综述,基于Gnutella的P2P电子商务模型的机制分析,研究了Gnutella的P2P电子商务模型的需求与功能,进行基于Gnutella的P2P电子商务模型总体架构设计.     

基于移动Agent的远程监控系统的设计与实现

该文在分析了引入移动代理计算模型的远程监控系统所具有的优势的基础上,提出了一种基于移动代理的现场总线与Internet集成架构网络环境下的远程监控系统模型结构,详细讨论了系统设计和实现的关键技术,并给出了系统代理的设计和关键代码。系统在应用中显示了良好的控制效果和运行稳定性。该方案充分利用了移动代理计算的优点,为大范围的协作的生产过程远程监控的时实和可靠的实现提供了一种新途径。     

移动网格体系结构及其资源选择方法

针对移动计算和网格计算的发展现状及其融合趋势,在分析现有移动网格架构的基础上,提出一种新的移动网格的集成框架,包括基于资源代理、服务代理和网关的移动网格的体系结构和逻辑构成,探讨了移动网格资源的基于客户请求的资源选择和分配办法,并列举了移动网格的应用实例。结果表明,通过代理和网关可充分利用移动网络的灵活性和有线网格的资源丰富性,实现移动网格资源的无缝访问和共享。     

移动IPv6中改进的代理容错机制研究

为了消除现有移动IPv6网络中单个家乡代理设备可能造成的单点故障和性能瓶颈问题,分析了目前的家乡代理容错和负载均衡机制,提出了一种主动检测过载预防的动态容错方法.该方法仅对家乡链路进行扩展,并在架构中增加智能均衡器,通过在其中维护代理列表和环状备份链进行容错,并采用家乡代理实时动态选择算法和切片机制支持负载均衡.建立了该方案的数学模型,分析了代理之间的状态转换关系.实验结果表明本方法可以有效减少移动节点的消息注册时间,增强了移动IPv6网络的可靠性.     

基于FIPA架构的移动服务中间件的设计与实现

在有基站的移动计算中,移动终端和计算机网络服务器之间是一个多对多的应用关系,移动终端使用网络服务资源,服务器向移动终端组播异构信息是其典型应用.本文给出了基于FIPA架构的,跨平台的移动服务中间件解决方案,在介绍FI-PA发展现状的基础上,阐述了该中间件的实现技术和应用结构,以多代理技术实现了移动计算与SOA的结合,扩展了JADE架构的组播功能.     

基于移动代理的普适计算模型研究与设计

针对普适环境下移动IP协议的局限性,将集智能性、移动性,安全性等诸多特性于一身的移动代理引入普适计算,详细地阐述了实现过程并进行性能分析与仿真实验.结果表明,普适移动设备在引入移动代理后,能够快速平滑地实现切换,从而大大减少了切换延迟和传输过程中的状态信息量,降低了移动设备在切换期间的丢包率,有效地改善了网络的性能.     

一个新型嵌入式移动性支持方案

IETF的移动IP协议存在代理的部署少、三角路由增加网络开销以及操作系统的支持有限等问题，未得到广泛应用。该文针对移动IP协议的不足，提出了一个新型的嵌入式移动性支持方案。该方案引入嵌入式移动代理和地址索引服务器来实现移动管理，最大限度地减小了移动管理对网络基础设施的依赖，为单个或成组移动设备提供了透明的移动服务。仿真实验表明，该移动性方案开销小、效率高，易于实现。     

Collaboration among mobile agents for efficient energy allocation in mobile grid

The use of mobile devices in grid environments may have two interaction aspects: devices are considered as users of grid resources or as grid resources providers. Due to the limitation constraints on energy and processing capacity of mobile devices, their integration into the Grid is difficult. In this paper, we investigate the cooperation among mobile devices to balance the energy consumption and computation workloads. Mobile devices can have different roles such as buyer devices and seller devices. In the mobile grid, the energies of mobile devices are uneven, energy-poor devices can exploit other devices with spare energy. Our model consists of two actors: A buyer device agent represents the benefits of mobile buyer device that intends to purchase energy from other devices. A seller device agent represents the profits of mobile seller device that is willing to sell spare energy to other devices. The objective of optimal energy allocation in mobile grid is to maximize the utility of the system without exceeding the energy capacity, expense budget and the deadline. A collaboration algorithm among mobile agents for efficient energy allocation is proposed. In the simulation, the performance evaluation of collaboration algorithm among mobile agents is conducted.     

A distributed mobile database implementation on Pocket PC mobile devices communicating over Bluetooth

This paper describes a distributed database system implementation built on top of stand-alone mobile databases found on mobile devices. At the heart of the architecture are elected devices that take on the role of data directories which collect the schema of the databases and become the contact points for all nodes that wish to submit queries against the distributed database. The system is implemented on Pocket PCs that run the Microsoft WinCE operating system and communicate using Bluetooth, thus limiting the architecture to eight devices, which is a restriction imposed by piconets. Sample databases were configured on the devices that ran the SQL Server CE database engine, and a list of 170 sample queries of varying complexities were designed to conduct performance evaluation. This evaluation involved measurement of query response time, generated traffic, and device energy consumption. The obtained results indicated the feasibility of the system and its potential for providing mobile users with a framework for aggregating disparate data that are stored in mobile databases in the wireless ad hoc network.     

A negotiation framework for content distribution in mobile transient networks

Transient networks are spontaneous networks that appear for a short period of time in order to provide basic services such as connectivity and content distribution among a small community. Nowadays mobile devices are becoming multimode by nature providing multiple connection paths. This paper investigates the efficiency and benefit of a mobile transient network where multiple nodes collaborate, offering a multihomed network with community services by means of intelligent agents. The paper concretely proposes an architecture able to fully support a peer-to-peer transient community during both negotiation and service steps for two different modes: file download and multimedia streaming. The first mode, implemented on intelligent and cooperative agents, provides two negotiation models (fair and dynamic) in order to guarantee wider flexibility for different possible scenarios and community models; the second one implements a content delivery system into transient community, taking advantage of multihomed features of mobile devices.     

An economics-based negotiation scheme among mobile devices in mobile grid

In this paper, we propose an economics-based distributed negotiation scheme among mobile devices in mobile grid. In our model, there are energy negotiation and transactions between buyer devices and seller devices. Dynamic allocation of energy resources in mobile grid is performed through online transactions within markets. Mobile devices can be sellers and buyers that use optimization algorithms to maximize predefined utility functions during their transactions. Seller device agents sell the underlying energy resources of the mobile device. Buyer device agent makes buying decisions within the budget constraints to acquire energy resources. An economics-based negotiation algorithm among mobile devices is proposed. The proposed algorithm decomposes mobile grid system optimization problem into a sequence of two sub-problems. In the simulation, the performance evaluation of economics-based negotiation algorithm is evaluated.     

A testing framework for mobile computing software

We present a framework for testing applications for mobile computing devices. When a device is moved into and attached to a new network, the proper functioning of applications running on the device often depends on the resources and services provided locally in the current network. This framework provides an application-level emulator for mobile computing devices to solve this problem. Since the emulator is constructed as a mobile agent, it can carry applications across networks on behalf of its target device and allow the applications to connect to local servers in its current network in the same way as if they had been moved with and executed on the device itself. This paper also demonstrates the utility of this framework by describing the development of typical network-dependent applications in mobile and ubiquitous computing settings.     

基于移动Agent的移动云计算系统构建方法

针对移动云计算面临的一系列问题,如应用程序在网络上迁移问题、远程设备上执行时的网络延迟和非持续连接问题、跨云服务问题以及安全风险和隐私问题,提出了一种基于移动Agent范型的移动云计算架构,其中,在应用程序迁移中引入断点保存思想和事件重播机制,在移动Agent协同过程中使用优化过的合同网协议,利用移动Agent交换密钥进行身份认证。用有色嵌套Petri网描述了此架构的执行流程,并在此基础上设计了移动电子图书销售系统。     

基于深度神经网络的移动端人像分割

针对现有的人像分割算法大多忽略移动设备的硬件限制，盲目追求效果，以致无法满足移动端对于分割速度要求的问题，提出了一种可在移动设备上高效运行的人像分割网络。首先，基于编码器-解码器的轻量级U型架构来构建网络；其次，为了克服全卷积网络（FCN）受制于较小的感受域，无法充分捕获长距离信息的缺陷，引入期望最大化注意力块（EMAU）置于编码器之后、解码器之前；然后，在训练阶段添加多层边界辅助损失，有助于提高人物边界轮廓的准确度；最后，对模型进行量化和压缩。在Veer数据集上将所提网络与PortraitFCN+、ENet和BiSeNet等网络进行对比实验。实验结果表明，所提网络可以提高图像推理速度和分割效果，并能够以95.57%的准确率处理分辨率为224×224的RGB图像。     

基于深度神经网络的移动端人像分割

针对现有的人像分割算法大多忽略移动设备的硬件限制，盲目追求效果，以致无法满足移动端对于分割速度要求的问题，提出了一种可在移动设备上高效运行的人像分割网络。首先，基于编码器-解码器的轻量级U型架构来构建网络；其次，为了克服全卷积网络（FCN）受制于较小的感受域，无法充分捕获长距离信息的缺陷，引入期望最大化注意力块（EMAU）置于编码器之后、解码器之前；然后，在训练阶段添加多层边界辅助损失，有助于提高人物边界轮廓的准确度；最后，对模型进行量化和压缩。在Veer数据集上将所提网络与PortraitFCN+、ENet和BiSeNet等网络进行对比实验。实验结果表明，所提网络可以提高图像推理速度和分割效果，并能够以95.57%的准确率处理分辨率为224×224的RGB图像。     

Mobile crowdsensing with mobile agents

We introduce mobile agents for mobile crowdsensing. Crowdsensing campaigns are designed through different roles that are implemented as mobile agents. The role-based tasks of mobile agents include collecting data, analyzing data and sharing data in the campaign. Mobile agents execute and control the campaign autonomously as a multi-agent system and migrate in the opportunistic network of participants’ devices. Mobile agents take into account the available resources in the devices and match participants’ privacy requirements to the campaign requirements. Sharing of task results in real-time facilitates cooperation towards the campaign goal while maintaining a selected global measure, such as energy efficiency. We discuss current challenges in crowdsensing and propose mobile agent based solutions for campaign execution and monitoring, addressing data collection and participant-related issues. We present a software framework for mobile agents-based crowdsensing that is seamlessly integrated into the Web. A set of simulations are conducted to compare mobile agent-based campaigns with existing crowdsensing approaches. We implemented and evaluated a small-scale real-world mobile agent based campaign for pedestrian flock detection. The simulation and evaluation results show that mobile agent based campaigns produce comparable results with less energy consumption when the number of agents is relatively small and enables in-network data processing with sharing of data and task results with insignificant overhead.     

Automatic form filling on mobile devices

Filling out forms for web based services on mobile devices is a very time consuming and frustrating task for users because of the limited text input capabilities. This is a critical bottleneck to obtaining a wide acceptance of such services, especially mobile commerce that often requires filling user data. We developed an architecture based on a local proxy on a mobile device and a lightweight algorithm for a comprehensive analysis of forms, which leads to the most probable user data to be filled in, driven by an initial rule set [Chie Noda, John Hamard, Enrico Rukzio, Alexander De Luca, Method and Apparatus for Automatic Form Filling on Mobile Devices, Patent. Publication number EP1777629, Publication date 2007-04-25]. We further discuss our implementation and the evaluation results for the algorithm as well as the usability of the prototype.