无结构P2P网络应用层组播的多播树研究

IP组播方案由于其自身的设计以及部署代价等问题未能获得大范围的推广,作为替代IP组播的一种方案,应用层组播已经成为一个重要的研究课题。同时基于覆盖网络的P2P网络的特性使得应用层组播方案得到实际的应用。本文以Gnutella例分析了无结构P2P网络的多播树生成过程,针对其多播树生成的随机性,提出了一种优化的多播树生成方法。性能分析显示,本文提出的多播树生成方法,使多播树的深度保持在可预测的范围,有效地优化了无结构P2P网络的多播树。     

视频流应用层组播系统设计与实现

本文设计实现了一个用于视频流分发的应用层组播系统,系统由视频采集、视频编解码、组播传输和服务器四个模块构成.视频捕获采用Video for Windows(VFW)技术实现,编解码基于H.263标准.网络结构上提出使用混合P2P树形结构,降低了中心服务器的压力.服务器负责会议成员信息的管理,为组播树的建立与维护提供支持.组播传输使用基于度约束的构造算法,考虑了节点带宽和计算能力.系统已投入运行,基本达到设计目标.     

基于应用层组播的实时流媒体负载分配方案

针对目前日益增长的音视频直播需求,设计了一种用于视频直播的实时流媒体负载分配方案。方案基于应用层组播技术,通过使用中间人（Broker）连接多个流媒体服务器来平衡负载,并可根据负载情况进行动态调整。在实际应用中,方案增加了传统单点流媒体服务器的连接数,并有效控制了音视频流的延迟时间。     

移动环境下的IP组播技术研究与实现

移动IP协议给出了支持主机移动的远程加入和双向隧道两种组播方法,它们具有一些互补的优缺点。提出的移动组播算法综合了这两种基本方法,同时,采用分层移动IP结构的路由思想,减少因主机移动而重构组播树的频率。使用了仿真软件OPNET8.1搭建了移动组播模块系统平台,同时,基于以上建立的平台,对视频会议进行组播应用,在移动环境下进行了拓扑结构的搭建和仿真实验,并对其仿真结果进行了分析和比较。     

IP组播技术及其基于宽带IP网的解决方案

文章介绍了组播的发展、分析了组播网络的体系结构和协议,讨论了基于宽带IP网的组播解决方案,总结了组播技术的难点.     

民用航空器维修执照口试系统的设计与关键技术研究

针对传统民用航空器维修口试中学生多教师资源少,以及考试的客观性和公平性难以保证的问题,设计了基于网络的计算机化技能口试系统,利用网络实现了多人同时进行执照技能口试,采取集中评分的形式保证了口试的公平性。此外,研究了口试的大型多媒体试题分发的关键技术,提出了一种新型的UDP结合TCP的应用层可靠组播协议,彻底解决了大型试题的快速分发难题,提高了网络效率。     

基于P2P软件的分布式拒绝服务攻击防御方法

因P2P软件和协议设计上的漏洞,无须入侵大量主机就可以发起大规模的分布式拒绝服务(DDoS)攻击。为此,提出一种分布式防御方法。通过在应用层构建一套数据发送授权机制,使点对点软件中的节点在未得到目标节点授权之前不能向其发送大量数据,从而阻止攻击数据到达被攻击者。     

基于P2P技术的信息检索

本文从基于P2P搜索的发展动机和原理入手,提出了一种层次化分布式哈希表系统——PDHS模型。该系统按物理网络的远近把节点划分为多个组,使得节点动态加入和退出的影响局限在单个组中,具有良好的稳定性和扩展性,部分查询的性能优越,适合在广域范围部署P2P应用。     

基于试飞测试的网络数据重组方法

为解决网络化机载测试系统中多台采集器的关键网络数据重组问题,研究网络化机载测试系统架构,提出一种网络数据重组方法,分析组播传输技术、基于XML的信息交换技术、iNET-X网络包和多采样率参数重组等关键技术,在某型民用飞机机载测试系统设计中,通过复用网络硬件资源,设计应用层软/硬件功能模块配置,实现了网络数据重组。试飞结果表明,能够从多台数据采集器的不同网络包中提取数据,并组包生成单一网络包,满足了试飞数据监控需求。     

独立组播协议PIM分析

详细介绍了PIM协议的工作原理,以及组播技术在现实中的实际应用。PIM有两种运行模式,一种是密集分布的组播组模式,称为独立组播协议密集模式PIM-DM（Protocol Independent Multicast Dense Mode）,另一种是稀疏分布组播组模式,称为独立组播协议稀疏模式PIM-SM（Protocol Independent Multicast Sparse Mode）。对这两种协议的实现机理进行分析。     

Predicting future dynamics from short-term time series using an Anticipated Learning Machine

Predicting time series has significant practical applications over different disciplines. Here, we propose an Anticipated Learning Machine (ALM) to achieve precise future-state predictions based on short-term but high-dimensional data. From non-linear dynamical systems theory, we show that ALM can transform recent correlation/spatial information of high-dimensional variables into future dynamical/temporal information of any target variable, thereby overcoming the small-sample problem and achieving multistep-ahead predictions. Since the training samples generated from high-dimensional data also include information of the unknown future values of the target variable, it is called anticipated learning. Extensive experiments on real-world data demonstrate significantly superior performances of ALM over all of the existing 12 methods. In contrast to traditional statistics-based machine learning, ALM is based on non-linear dynamics, thus opening a new way for dynamics-based machine learning.     

工程监理保险的资产负债管理

首先介绍了ALM产生的背景及其发展,然后对ALM模型进行了相关论证。考虑到中国保险业投资渠道的发展现状和工程监理保险实务,在此基础上最终建立起了ALM模型。     

期限结构模型在资产负债管理问题中应用的探讨

本文说明了期限结构模型在资产负债管理中的运用，指出为了保持证券估值的精确性，在资产负债管理模型中必须合理地逼近不确定性。     

论商业银行资产负债优化的资本约束

本文以新巴塞尔协议对资本约束的有关要求为背景,深入探讨了商业银行风险损失与其资本准备的关系。研究认为商业银行资产负债管理必须受到经济资本的约束,其非预期损失必须控制在经济资本范围以内,论文还引入VaR框架对商业银行资产负债管理和优化的资本约束条件作了定量分析,为在实践中计量和控制风险提供了具有较强操作性的方法。     

基于优先级的动态分层应用层多播模型

应用层多播(ALM)作为IP多播的替代在互联网中得到广泛的应用。提出一个新的基于优先级的动态分层应用层多播模型CDMP(The Classified Dynamic Model Based on the Priority in Application-Level Multicast),模型通过对不同性质的结点的分层来搭建整个架构,通过分域将性质接近的结点放在一起以保证数据传输的效率和数据共享的公正性,并且减少了结点寻找路由的代价,加快了当结点失败时的路由修复速度。通过分析和仿真实验证明,CDMP协议具有良好的上述性质。     

Altmetrics – a complement to conventional metrics

Emerging metrics based on article-level does not exclude traditional metrics based on citations to the journal, but complements them. Both can be employed in conjunction to offer a richer picture of an article use from immediate to long terms. Article-level metrics (ALM) is the result of the aggregation of different data sources and the collection of content from multiple social network services. Sources used for the aggregation can be broken down into five categories: usage, captures, mentions, social media and citations. Data sources depend on the tool, but they include classic metrics indicators based on citations, academic social networks (Mendeley, CiteULike, Delicious) and social media (Facebook, Twitter, blogs, or Youtube, among others). Altmetrics is not synonymous with alternative metrics. Altmetrics are normally early available and allow to assess the social impact of scholarly outputs, almost at the real time. This paper overviews briefly the meaning of altmetrics and describes some of the existing tools used to apply this new metrics: Public Library of Science - Article-Level Metrics, Altmetric, Impactstory and Plum.Key words: altmetrics, article-level metrics, citation, social media     

系统科学的五大理论突破

从经典科学到系统科学范式的转换,实现了理论层次的重大突破。整体论是系统科学的形而上学基础;在学科定位方面,突破了经典科学的学科边界,具有跨学科特征;在认识论方面实现了从实在论向建构论的转变;在理论特征方面实现了从构成论向生成论的转变,生成论成为了系统科学的灵魂;在研究对象方面,实现了从＂实物性＂向＂关系性＂的转变。     

Modeling of Star-shaped and Parallel-wire Carrier Distribution Systems

It is often desirable to represent carrier distribution systems by networks so that analysis can be made to predict the behavior of these systems. Modeling of two canonical carrier distribution systems, the star-shaped system and the parallel-wire system by networks was carried out in this paper. The representation is given in terms of lumped parameters when the lengths of the carrier lines are short and it is given in terms of lumped and distributed parameters when the lengths of the carrier lines are long.     

Active control for flexible mechanical systems with mixed deadzone-saturation input nonlinearities and output constraint

There exist mixed deadzone-saturation input nonlinearities and output constraint in the practical implementation environment for flexible mechanical systems, and they have crucial influences on the performance of flexible systems. In this paper, two class of flexible structures are investigated and analyzed by designing the active boundary vibration control with auxiliary systems. Based on the infinite dimensional dynamic model of flexible mechanical systems, the barrier logarithmic terms are brought into the Lyapunov function and boundary vibration control laws for maintaining the output signals within the constrained region. Besides, the auxiliary terms are designed in the control laws to compensate for mixed nonlinear inputs which integrate the deadzone and saturation characteristics. With the simulation results, the theoretical analysis for the flexible mechanical systems is verified to be correct and the designed control laws are effective.     

Spatiotemporal sampled-data fuzzy control for switched singularly perturbed PDE systems with average dwell-time switching mechanism

This paper investigates a spatiotemporal sampled-data fuzzy control strategy for switched singularly perturbed partial differential equation (PDE) systems, where the systems’ operation modes obey average dwell-time switching mechanism. To efficiently deal with nonlinear terms and guarantee the system stability for the considered systems, a spatiotemporal sampled-data fuzzy control scheme is developed. Furthermore, based on the fact that mode mismatch phenomena during switching and sampling, through formulating novel Lyapunov functionals (LFs) with the discontinuous terms and mode-dependent two-sided looped-functionals, which can fully utilize the state information of the sampling period, a new exponential stability criterion is provided for the target systems. Finally, an example is provided to prove the validity of the proposed control approach.