A traffic flow density adaptive broadcast protocol for VANETs

为了实现车用自组织网络(VANET)在交通流实时变化的场景下对安全信息的快速、有效广播,提出了一种能够适应交通流密度变化的VANET广播协议——交通密度自适应广播协议(TDABP).该协议针对VANET环境的特点,采用了基于节点覆盖信息的分布式广播策略,采取按需交换邻节点覆盖信息的方式来选择转发节点,有效地降低了更新邻节点信息的通信开销、减小了广播风暴的影响,使广播通信不受节点密度的影响,能够适应道路交通中交通流不断变化的VANET广播场景.理论分析和仿真实验结果表明,该VANET广播协议能够满足VANET广播的可靠性和实时性要求,能够适应交通流引起的节点密度变化,具有良好的可扩展性和较高的广播效率.     

超宽带无线传感器网络的一种节能误码率门限设置策略

为了优化网络性能和延长传感器节点寿命,结合超宽带信号的特点研究了物理层接收机处的误码率门限与传感器节点的无线通信能耗之间的关系,建立了物理层能耗优化模型并提出了使得传输每比特信息平均能耗最小化的误码率门限设置策略(BER-TSS)。由BER-TSS设置的最优误码率门限可较好地在传输能耗与出错信息重传能耗之间进行平衡,从而使得每比特信息平均传输能耗最小。仿真结果表明,在不同的无线信道条件下,BER-TSS可较大幅度削减每比特信息平均传输能耗,并且必须结合网络业务的时延要求适当地设置接收信号BER门限。     

基于混合拓扑的机械无线传感器网络多信道数据传输方法

针对机械振动无线传感器网络节点因信道带宽窄导致网络传输速率过低,在大量原始数据传输需求下实时性较差的问题,提出一种基于簇树星型混合拓扑的多信道数据传输方法。对各传感器网络节点进行树间通信干扰最小化信道分配,避免邻频干扰影响树间并行通信,在数据同步采集结束后,各节点以分配信道组建簇树星型混合拓扑网络进行数据传输;采用树间通信握手机制和树间通信优先级抢占机制解决簇树星型混合拓扑带来的树间互盲问题;将各采集节点短地址作为调度信息载入信标进行广播,各采集节点根据调度信息决定进行数据传输或者休眠,实现树内通信能耗最小化时序调度。将提出的多信道数据传输方法与载波侦听多路访问/冲突避免机制进行对比,实验结果表明该方法能有效提高机械振动无线传感器网络数据传输速率。     

卡尔曼滤波在无线传感器网络节点定位中的应用

为了减小无线传感器网络节点定位中节点测距误差和定位算法自身引入误差的积累对定位精度的影响,建立了适用于无线传感器网络的卡尔曼滤波模型.采用渐消自适应卡尔曼滤波对基于距离的初始定位算法进行求精,通过一跳节点间的相互制约,在全局范围对未知节点进行定位;基于卡尔曼滤波模型,对无线传感器网络的分布式算法和集中式算法的计算量进行了研究,得出计算量与节点数目的关系.研究结果表明,卡尔曼滤波能够有效提高节点的定位精度,尤其适用于网络节点密度小、信标节点比例低的情况.     

一种传感器网络的非均匀节能分簇模型

针对无线传感器网络中节点能耗不平衡导致系统生存时间缩短的问题,提出了一种无线传感器网络的非均匀节能分簇(UEEC)模型.UEEC通过自组织的方式和对簇头的动态选择,在靠近sink点(基站)的地方形成较小的簇,在远离sink点的地方形成较大的簇,从而使簇头能够对信息收集能耗与信息转发能耗进行平衡.同时,簇头的动态选举又能够把能耗平均分散在各个节点上.仿真结果表明,UEEC在减少与平衡无线传感器网络的节点能耗上有较好的性能,从而能够延长无线传感器网络的生存时间.     

一种新的分布式无线传感器网络定位方法

针对无线传感器网络节点能源受限的特征,以系统最小硬件开销为设计原则,提出了一种适用于基于测距的分布式定位方法(3/2-NANDB),该方法可在不增加单个独立节点硬件开销的情况下,利用附加的外部控制系统发射一个旋转定向波束充分挖掘节点间的冗余信息,有效排除节点位置的模糊性,从而可完全确定只有两个邻居节点的节点位置和部分只有一个邻居节点的节点位置,达到减少GPS携带节点数量、最大化网络内部可定位节点数目、扩大网络观察范围和延长无线传感器网络存活时间等目的.而利用该方法的节点二义性排除算法,还可以辅助其他现有的基于三邻居(3-NA)的定位算法提高整体定位性能.     

基于小世界的无线传感器网络拓扑结构

将小世界理论引入无线传感器网络,提出一种基于小世界的无线传感器网络拓扑结构,并针对网络寿命与层次型拓扑结构进行仿真比较,实验表明,基于小世界的无线传感器网络拓扑结构能够减少网络能耗,延长网络生存时间。     

面向传感网可信检测的协同感知策略

为了提高基于传感器网络的目标检测的检测精度和尽可能延长网络的寿命,将满足用户对检测精度要求的检测定义为可信检测,并提出了一种面向可信检测的协同感知策略。该策略首先对传感器的相关性及感知能力差异性进行定量分析,发现它们与传感器簇的感知性能的关联性,为实现传感器的协同选择提供依据;然后用一种分布式传感器协同选择方法进行传感器协同选择:根据传感器相关性、感知能力差异性及剩余能量来计算节点的重要性,之后按节点重要性选择合适的传感器。试验表明,与传统方法相比,该策略既能更好地满足用户对检测精度的要求,又能在实现能量均衡、延长网络寿命上取得更好的效果。     

一种低计算复杂度的无线传感器网络分簇定位算法

针对已有的集中式定位算法定位精度低,而分布式定位算法计算复杂度高、通信量大的问题,提出了一种适用于无线传感器网络的计算复杂度低的节点分簇定位算法.首先,提出满足最大连通度的多边界节点分簇算法,采用此算法把网络划分为若干个簇,各簇分别进行簇内节点定位;其次,各簇进行融合,最终实现全网节点的定位.仿真结果表明,这种分簇定位算法比分布式定位算法计算复杂度低、通信量小、定位精度相当或略差,比集中式定位算法计算复杂度低、通信量小、定位精度高.采用该算法可以降低传感器网络节点定位过程中的能耗,提高计算效率,延长网络寿命.     

无线传感器网络WSN硬件设计

传感器网络节点作为一种微型化的嵌入式系统,构成了无线传感器网络的基础层支撑平台。因为无线传感器网络大部分是采用电池供电,工作环境通常比较恶劣,而且数量大,更换电池非常困难,所以低功耗是无线传感器网络最重要的设计准则之一,从无线传感器网络节点的硬件设计到整个网络各层的协议设计都把节能作为设计的目标之一,尽可能延无线传感器网络的寿命。本文介绍了无线传感器网络的概念、特点以及无线传感器网络节点的组成,重点分析比较节点各组成单元各种常用芯片的特点,并且始终将低功耗作为比较的重要标准之一。     

Modelling photosystem I as a complex interacting network

In this paper, we model the excitation energy transfer (EET) of photosystem I (PSI) of the common pea plant Pisum sativum as a complex interacting network. The magnitude of the link energy transfer between nodes/chromophores is computed by Forster resonant energy transfer (FRET) using the pairwise physical distances between chromophores from the PDB 5L8R (Protein Data Bank). We measure the global PSI network EET efficiency adopting well-known network theory indicators: the network efficiency (Eff) and the largest connected component (LCC). We also account the number of connected nodes/chromophores to P700 (CN), a new ad hoc measure we introduce here to indicate how many nodes in the network can actually transfer energy to the P700 reaction centre. We find that when progressively removing the weak links of lower EET, the Eff decreases, while the EET paths integrity (LCC and CN) is still preserved. This finding would show that the PSI is a resilient system owning a large window of functioning feasibility and it is completely impaired only when removing most of the network links. From the study of different types of chromophore, we propose different primary functions within the PSI system: chlorophyll a (CLA) molecules are the central nodes in the EET process, while other chromophore types have different primary functions. Furthermore, we perform nodes removal simulations to understand how the nodes/chromophores malfunctioning may affect PSI functioning. We discover that the removal of the CLA triggers the fastest decrease in the Eff, confirming that CAL is the main contributors to the high EET efficiency. Our outcomes open new perspectives of research, such comparing the PSI energy transfer efficiency of different natural and agricultural plant species and investigating the light-harvesting mechanisms of artificial photosynthesis both in plant agriculture and in the field of solar energy applications.     

Software-Defined Space-Air-Ground Integrated Network Architecture with the Multi-Layer Satellite Backbone Network

Under the background of the rapid development of ground mobile communication, the advantages of high coverage, survivability, and flexibility of satellite communication provide air support to the construction of space information network. According to the requirements of the future space information communication, a software-defined Space-Air-Ground Integrated network architecture was proposed. It consisted of layered structure satellite backbone network, deep space communication network, the stratosphere communication network and the ground network. The SpaceAir-Ground Integrated network was supported by the satellite backbone network. It provided data relay for the missions such as deep space exploration and controlled the deep-space spacecraft when needed. In addition, it safeguarded the anti-destructibility of stratospheric communication and assisted the stratosphere to supplement ground network communication. In this paper, algorithm requirements of the congestion control and routing of satellite backbone protocols for heterogeneous users’ services were proposed. The algorithm requirements of distinguishing different service objects for the deep space communication and stratospheric communication network protocols were described. Considering the realistic demand for the dynamic coverage of the satellite backbone network and node cost, the multi-layer satellite backbone network architecture was constructed. On this basis, the proposed Software-defined Space-Air-Ground Integrated network architecture could be built as a large, scalable and efficient communication network that could be integrated into space, air, and ground.     

网络时代的三大基本定律与骨干网容量的演进

文章首先分析了新时期的巨大挑战及其对网络的深远影响,特别指出了网络面临的巨大容量压力。接下来分别就主宰网络时代的三个基本定律：摩尔定律、光纤定律和迈特卡尔夫定律的内涵、影响和技术极限进行了论述。最后探讨了骨干网传输链路、传送节点和业务节点的容量演进策略。     

电磁驱动分置式斯特林制冷机综合网络模型

根据系统动力学建立了电磁驱动分置式斯特林制冷机整机的综合网络模型。该模型综合分析了电磁驱动分置式斯林特制冷机的流体网络，热声网络以及机电网络的有关研究成果，并加以完善，比较全面地反映了电磁驱动分置式斯林制冷机各个方面的动态特性，以此为基础编制的制冷机整机仿真程序，为分置式斯林特林制冷机的整机优化设计，离线调机，在线控制等行为提供了依据。     

Deterministic global optimization approach to steady-state distribution gas pipeline networks

Natural gas is normally transported through a vast network of pipelines. A pipeline network is generally established either to transmit gas at high pressure from coastal supplies to regional demand points (transmission network) or to distribute gas to consumers at low pressure from the regional demand points (distribution network). In this study, the distribution network is considered. The distribution network differs from the transmission one in a number of ways. Pipes involved in a distribution network are often much smaller and the network is simpler, having no valves, compressors or nozzles. In this paper, we propose the problem of minimizing the cost of pipelines incurred by driving the gas in a distribute non-linear network under steady-state assumptions. In particular, the decision variables include the length of the pipes’ diameter, pressure drops at each node of the network, and mass flow rate at each pipeline leg. We establish a mathematical optimization model of this problem, and then present a global approach, which is based on the GOP primal-relaxed dual decomposition method presented by Visweswaran and Floudas (Global optimization in engineering design. Kluwer book series in nonconvex optimization and its applications. Kluwer, Netherlands, 1996), to the optimization model. Finally, results from application of the approach to data from gas company are presented.     

面向对象的神经网络类库

提出一种面向对象的神经网络类库的构造方法。该类库采用面向对象的方法，集成了当前比较成熟的人工神经网络模型，充分利用了ＯＯＰ方法的继承性、封装性和多态性，便于在现有基础上派生出新的神经网络模型。该类库将被用于实现一种最新的同步振荡神经网络－ＬＥＧＩＯＮ网络。由于系统的结构性和代码的可重用性，既有利于科研工作者进行神经网络的研究，也便于工程人员的神经网络应用。     

信息网络--现代信息工程学的前沿

信息网络正在各地迅猛崛起,并以史所罕见的规模和速度生长成为世界性社会基础结构,深刻地改变着人们的生产方式、工作方式、学习方式、交往方式、生活方式和思维方式,成为工程学界以至整个社会普遍关注的集点、热点和前沿。文章旨在从理论上廓清信息网络的概念,阐明为什么信息网络对于科学技术的进步、对于世界经济和人类社会的发展能够产生如此巨大和深远的作用与影响。在此基础上,论述信息网络在现代工程学中的作用与地位,以及信息网络工程学在当前的主要研究内容和方向。     

A TWO-PHASE NETWORK DESIGN HEURISTIC FOR MINIMUM COST WATER DISTRIBUTION SYSTEMS UNDER A RELIABILITY CONSTRAINT

This paper presents a two-phase design and optimization procedure for constructing a pipe network water distribution system having a built-in degree of reliability. The first phase is comprised of an algorithm called TREESEARCH which iteratively constructs a tree pipe network. Starting with a shortest-path based tree, the procedure employs a linear programming subproblem to systematically modify this tree by adding and deleting one link at a time, with the aim of reducing the cost of the network while satisfying the flow continuity, energy balance, and pressure head requirement constraints. The second phase of the algorithm, called REDUNDANCY, is concerned with the issue of reliability. In this phase, the tree network constructed by the algorithm TREESEARCH is augmented through the addition of links so that there are at least two arc-disjoint paths from each source node to every demand node it serves. This augmentation is performed through the use of a set covering problem which recommends the links to be added, and a Hardy-Cross solver for redesigning the perturbed network to ensure feasibility, while attempting to minimize the overall design cost. The two phases are coordinated by applying algorithm REDUNDANCY to several candidate solutions presented by TREESEARCH. Two example problems from the literature, one involving a single source and the other a multiple source network, are solved using the proposed procedure. The solutions obtained have a smaller cost than those previously obtained by other researchers.     

一类非对称离散Hopfieid网络的收敛性

讨论了一类特殊的非对称离散Ｈｏｐｆｉｅｌｄ网格在串行和并行两种方式下的收敛性问题。证明了该类网络在串行方式下至多经２ｎ步（ｎ为神经元个数）可收敛到平衡点；在并行方式下或者收敛到一平衡点或者进人２─圈。     

快速以太校园网结构设计研究

目的 研究适用于切实可行的、符合校园网络技术发展的快速以太校园网络结构。方法 通过需求分析寻找网络传输瓶颈，分析相关以太网技术。结果与结论 提出一种快速以太校园网络结构，这种结构能够满足校园网信息传输需求。