一种用于流控和资源管理的区分业务Fast-TCP机制

该文提出了一种传统TCP技术的改进方案基于区分业务的 Fast-TCP 机制,简称区分业务F-TCP。通过探讨和借鉴相关的流控、调度及队列管理策略,进一步提出了区分业务F-TCP的实现算法。大量的仿真结果证实了这种机制及其实现算法的可行性和有效性,以及相关的缓冲区占用量突发的估计公式。该机制可在现有的Internet网络中有效地提供业务区分。     

一种基于QoS特征的多媒体业务区分方法

准确、高效的业务流识别和分类是保障多媒体通信端到端服务质量(Quality of Service,QoS)和执行相关网络操作的前提。但多媒体通信业务构成复杂,具有较严格的QoS约束,且存在包/流水平统计特征多样性,因此业务统计特征有效选取直接关系到识别和分类方法的有效性。针对流行的多媒体业务,分析了典型的业务特征,从业务QoS保证角度,选取区分特征,基于隐马尔可夫模型(Hidden Markov Model,HMM),对多媒体业务在QoS类上进行区分,实现简单,能以较小的空间复杂度较快地识别出多媒体业务流,有利于提高分类准确度。通过仿真验证了该方法的有效性。     

一种基于区分服务和AMR编码技术的VoIP QoS解决方案

文章提出了一个将网络和终端相结合的VoIPQoS方案.该方案在网络提供区分服务的基础上,终端采用AMR(Adaptive Multi-Rate)语音编码技术,编码率根据网络状况自适应地调整.模拟实验表明,此方案能够较好地使网络和终端协调工作来保证QoS.     

一种支持区分业务的智能光网络RWA方法北大核心

针对差异化的用户QoS(服务质量)需求,提供支持区分业务的RWA(路由和波长分配)算法是光网络当前研究的重点。文章提出了一种改进的支持区分服务的智能光网络GWAS(分组波长分配策略),针对不同等级的业务采用动态可调整的波长分组方案以实现差异化QoS。仿真结果表明,GWAS方案可以保证高优业务比低优业务具有更好的性能:在每根光纤复用9波长和160波长情况下,Mesh与NSFNET网络中高优业务比低优业务的阻塞率在相同业务负荷下最大降低24%与18%和15%与10%。     

IEEE802.11无线局域网中一种支持业务区分的回退算法

支持QoS的MAC机制是WLAN支持QoS的关键所在.我们已经给出了一种低分组碰撞概率的MAC层回退机制——RWBO+BEB.该文进一步讨论如何让RWBO+BEB支持业务区分的问题.首先提出了一个Markov链模型,分析如何根据无线终端的带宽比率设置最小竞争窗口,然后给出了一种新的支持业务区分的回退算法——DS-RWBO,仿真结果表明,DS-RWBO能根据局域网中每个终端的带宽比率分配无线信道的带宽资源.     

一种采用两级缓冲调度区分业务的帧聚合策略

帧聚合是改善无线MAC(Media Access Control)协议信道利用率,提高频谱效率的有效手段之一。该文针对多业务场景,采用两级缓冲区调度策略,按照不同聚合权重因子对各队列轮询聚合。根据各个队列的包超时紧迫因子动态调整各队列的聚合权重,以满足各QoS等级业务的时延限制。该文还将排队论模型引入到帧聚合策略的性能分析中,建立了系统的数学分析模型,定量分析了主要性能参数与系统负载的关系。通过与IEEE 802.11n标准中定义的两层帧聚合策略比较表明,该文提出的帧聚合策略的性能优于IEEE 802.11n两层帧聚合策略。     

IP QoS中的综合业务和区分业务

IP QoS是现代互联网发展中的一项关键技术。IETF已经定义了几种体系结构以解决IP QoS的诸多问题。介绍了其中的两个主流体系结构：综合业务和区分业务，并提出将二者进行结合，从而为下一代互联网提供更好的IP QoS。     

一种基于区分服务的VoIP访问控制体系

本文基于区分服务网络体系对访问控制方法进行了研究,提出了一种改进的访问控制体系。该体系以探测流和正常数据包附加测试标记的方式获取网络状况信息。据此适应性调整边界路由器的标记、资源分配等参数,使得语音数据在网络拥塞等状况下也能够获得有效服务,进一步提高网络的资源利用率。     

区分业务及其在IP城域网的实施

传统的尽力而为的转发机制由于Internet的飞速发展,已经不能满足用户的要求。为此,对区分业务方案的具体系结构及实现环节作了详细的介绍,并讨论了其在IP城域网的实施。与其它机制相比,区分业务实现简单、系统开销少,能在骨干网中有效地保证服务质量。     

基于区分业务技术的IMS QoS机制

IP多媒体子系统(IMS)是3GPP在R5版本中提出的针对多媒体业务的控制领域,可以提供任何形式的IP业务,如语音／视频电话、视频流、即时多媒体消息、多媒体游戏等。文章介绍了在IMS环境中通过区分业务(Diffserv)技术以及一些相关的简单但易扩展的IP QoS技术来提供QoS支持,还介绍了基于区分业务(Diffserv)技术来提供QoS支持所涉及到的一些主要的网络元素。     

一种应用于动态数字全息的快速相位解包裹算法

为满足动态数字全息的实时、在线检测分析的需求,提出了一种应用于动态数字全息的快速相位解包裹算法。在充分考虑相位解包裹的精确性和运行时间的基础上,首先找出影响解包裹精确性的坏点,并进行标记;采用运行速度较快的中心点辐射解包裹算法,使解包裹路径避开这些坏点,并利用动态全息相位图在时域上的关联;在时域上设置解包裹路径,以解决不同帧的相位值在时域上的关联问题和坏点封闭区域的相位解包裹问题。实验结果表明,本文算法是合理和有效的,运行速度较快,解包裹的精确性较高。     

Bridging the gap between dynamic and static methods for cellplanning

Frequency reuse distance is a crucial parameter in cellular system design that determines the service quality, which is usually measured in terms of the signal-to-interference ratio (SIR). The instantaneous SIR is a random variable; theoretically, its characterization is completely provided by the outage probability. In cellular engineering, however, frequency reuse planning is usually based on a simple static design, without taking into account the dynamic propagation effects. The static method has the advantage of simplicity, but failing to indicate the system dynamic performance. In this paper, we determine a simple mathematical expression between the static and dynamic SIRs whereby a new cell planning technique is developed. The new technique makes it possible to incorporate dynamic considerations into a static design thereby bridging the gap between the two methods. We also use the new results to study the system capacity, revealing the dependence of the system capacity on the minimum required outage probability     

A dynamic and quasi-centralized RWA method for optical fast circuit switching networks employing route pre-prioritization

We propose a new dynamic RWA algorithm for optical fast circuit switching networks, agile optical networks that can accommodate changing broadband demands. The algorithm utilizes pre-computed prioritized route candidates that reflect statistical information such as traffic distribution characteristics to attain better load balancing. The route priority is periodically distributed over a network and RWA for each path connection demand is processed in a distributed manner. Numerical experiments demonstrate that the algorithm matches the performance of a centralized RWA algorithm that uses all the necessary information on a network.     

一种动静PIR相结合的目标定位方法

针对目前热释电红外(PIR)传感器在静态人体 检测方面的局限性,提出了一种在动态下利用多PIR传感器、 动静相结合对人员目标进行检测、测向与定位的方法。研究中,感知节点上的静态PIR传感 器对人员目标进行 测距,动态PIR传感器以10°/s的速率对监控区域往复式扫描,变被动为“主动”。当人员 目标与PIR传感器的探测视线 相交时,通过帧差法得到目标的角度值,融合多个传感器的测量值进行交叉定位,实现了在 探测区域对整 个目标事件过程的有效数据采集。实验证明,本文方法能很好地对不同状态下的人员目标进 行检测定位,具有实用价值。     

一种面向多类型服务的动态负载均衡算法

针对航空物流ILink数据平台交易复杂性高、服务种类多、业务规模大等特点,提出一种面向多类型服务的动态负载均衡算法。通过分析四种基本服务类型以及实时采集四种服务类型的资源消耗,根据用户服务请求类型的不同动态调整各服务器的负载,引入了过载服务器节点缓冲机制缓冲负载过重节点,有效解决了航空物流ILink数据平台可能出现的用户等待时间过长、局部负载过重、甚至个别服务器节点崩溃的问题,达到了集群的负载均衡。仿真实验结果表明,提出的算法在系统吞吐量、系统响应时间、负载率等关键指标上优于经典的比率算法和遗传算法。     

区分服务模型中的一种动态队列管理算法

在对区分服务模型和RED算法进行分析的基础上，提出了一种基于RED算法的动态队列管理算法。实验结果证明，我们提出的算法在不损害高优先级数据流量的情况下，能较好地实时调整各优先级的门限值，减少网络资源的消耗，提高网络资源的利用率。     

A library of static and dynamic communication algorithms for parallel computation

Communication efficiency is one of the keys to the broad success of parallel computation, as one can see by looking at the successes of parallel computation, which are currently limited to applications that have small communication requirements, or applications that use a small number of processors. In order to use fine grain parallel computation for a broader range of applications, efficient algorithms to execute the underlying interprocessor communications have to be developed. In this paper we survey several generic static and dynamic communication problems that are important for parallel computation, and present some general methodologies for addressing these problems. Our objective is to obtain a collection of communication algorithms to execute certain prototype communication tasks that arise often in applications. These algorithms can be called as communication primitives by the programmer or the compiler of a multiprocessor computer, in the same way that subroutines implementing standard functions are called from a library of functions in a conventional computer. We discuss both algorithms to execute static (deterministic) primitive communication tasks, as well as schemes that are appropriate for dynamic (stochastic) environments. Our emphasis is on algorithms that apply to many similar problems and can be used in various network topologies. This revised version was published online in June 2006 with corrections to the Cover Date.     

A quasi-distributed dynamic and static strain sensor system

A quasi-distributed dynamic and static strain sensor system consisting of 16 FBG sensors is designed by using an ampli-fied-sponteneous emission(ASE) optical source,an optical tunable filter and a tunable laser.A resolution of about 5με has been achieved for dynamic strain measurement.The resolution for static strain measurement is about 1 με     

A quasi-distributed dynamic and static strain sensor system

A quasi-distributed dynamic and static strain sensor system consisting of 16 FBG sensors is designed by using an amplified-sponteneous emission （ASE） optical source, an optical tunable falter and a tunable laser. Aresolution of about 5 με has been achieved for dynamic strain measurement. The resolution for static strain measurement is about 1 με.     

A comparison of static and dynamic characteristics between rectuseye muscle and linear muscle model predictions

The characteristics of a muscle model are analyzed using rectus eye muscle parameter values and compared to rectus eye muscle data. The muscle is modeled as a viscoelastic parallel combination connected to a parallel combination of active state tension generator, viscosity element, and length tension elastic element. Each of the elements is linear and their existence is supported with physiological evidence. The static and dynamic properties of the muscle model are compared to rectus eye muscle data. The length-tension characteristics of the model are in good agreement with the data within the operating region of the muscle. With the muscle model incorporated into a lever system to match the isotonic experiment paradigm, simulation results for this linear system yield a nonlinear force-velocity curve. Moreover, the family of force-velocity curves generated with different stimulus rates reported in the literature match the predictions of the model without parametric changes. The results of this paper are important in studies involving the oculomotor plant and oculomotor neural networks. Additionally, these results may be applicable to other muscles.