一种新的相机外参数标定方法

为了更精确地对飞机姿态进行交会测量,提出了一种新的外参数标定装置来获得相机参数。首先通过高精度全站仪获得标定杆上圆形标记点在世界基准坐标系下的坐标,然后通过摄像测量仪采集标定杆图像,对其进行高精度椭圆拟合得到标记点在像素坐标系下的坐标,在已知相机内参数的情况下求解世界基准坐标系到相机坐标系的旋转矩阵和平移向量。已知距离标记点验证实验结果表明:相邻点间平均距离误差为0.128 8mm,具有较好的易操作性和标定精度。     

一种适用于分布式摄像机网络的SCIWCF算法

本文使用容积卡尔曼滤波器来处理分布式摄像机网络中的目标跟踪问题.平方根容积信息滤波（Square-Root Cubature Information Filter,SCIF）是容积卡尔曼滤波的一种扩展,其具有有效性和可靠性等方面优势,有利于对多源信息进行信息融合.然而当该算法应用于像摄像机网络这种大规模网络时,如果采用一般的集中式处理,中心节点可能会承受较大的计算压力.针对这个问题,本文首先将平方根容积信息滤波器进行了扩展,提出分布式平方根容积信息滤波器,使其能适应大规模网络.另外在摄像机网络中,由于摄像机装置在一个较大的区域内,由于摄像机观测区域有限,目标可能会出现在观察的盲区,这样就会存在某些摄像机的测量数据无效.针对这个问题,本文提出了平方根容积信息加权一致性滤波器（Square-Root Cubature Information Weighted Consensus Filter,SCIWCF）对状态信息和信息矩阵加权,减小这些无效信息在一致性算法的作用,从而提高整体的滤波性能.仿真实验结果表明,本文提出的算法能够在摄像机网络中对目标进行有效跟踪,在估计精度和滤波器稳定性等方面要优于传统的信息滤波.     

Smart Camera Networks in Virtual Reality

This paper presents our research towards smart camera networks capable of carrying out advanced surveillance tasks with little or no human supervision. A unique centerpiece of our work is the combination of computer graphics, artificial life, and computer vision simulation technologies to develop such networks and experiment with them. Specifically, we demonstrate a smart camera network comprising static and active simulated video surveillance cameras that provides extensive coverage of a large virtual public space, a train station populated by autonomously self-animating virtual pedestrians. The realistically simulated network of smart cameras performs persistent visual surveillance of individual pedestrians with minimal intervention. Our innovative camera control strategy naturally addresses camera aggregation and handoff, is robust against camera and communication failures, and requires no camera calibration, detailed world model, or central controller.      

Distributed Restoration in Optical Networks using Feed-forward Neural Networks

A new method is proposed for determining protection paths in an optical network where users have different characteristics in terms of reliability needs and security restrictions. Survivability is achieved by distributed mesh protection. Over the preplanned primary and backup capacity, optimal routing and wavelength assignment is carried out. In case of a network failure, protection routes and optimum flow values on these protection routes are extracted from a previously trained feed-forward neural network which is distributed over the optical data communications network.     

Asynchronous Distributed Averaging on Communication Networks

Distributed algorithms for averaging have attracted interest in the control and sensing literature. However, previous works have not addressed some practical concerns that will arise in actual implementations on packet-switched communication networks such as the Internet. In this paper, we present several implementable algorithms that are robust to asynchronism and dynamic topology changes. The algorithms are completely distributed and do not require any global coordination. In addition, they can be proven to converge under very general asynchronous timing assumptions. Our results are verified by both simulation and experiments on Planetlab, a real-world TCP/IP network. We also present some extensions that are likely to be useful in applications.     

Pre-electing a Leader in Distributed Networks

In this article the leader election algorithm based on the performance and operation rate of nodes and links is proposed.     

Incremental Adaptive Strategies Over Distributed Networks

An adaptive distributed strategy is developed based on incremental techniques. The proposed scheme addresses the problem of linear estimation in a cooperative fashion, in which nodes equipped with local computing abilities derive local estimates and share them with their predefined neighbors. The resulting algorithm is distributed, cooperative, and able to respond in real time to changes in the environment. Each node is allowed to communicate with its immediate neighbor in order to exploit the spatial dimension while limiting the communications burden at the same time. A spatial-temporal energy conservation argument is used to evaluate the steady-state performance of the individual nodes across the entire network. Computer simulations illustrate the results.     

应用于光网络的分布式故障恢复策略

网络规模的增大和复杂程度的提高给现有的集中式故障恢复策略的实施带来了困难,而分布式恢复策略可以有效地减少网络规模与故障恢复之间的相关性。结合基于DCS的分布式恢复的思想,分别就光网络的单链路故障,节点和多链路故障以及分布式的共享恢复问题进行了分析并讨论了相应的解决方案,最后给出了研究中一些有待解决的问题和对分布式恢复技术的展望。     

Multitarget Tracking in Distributed Sensor Networks

In this article, a survey of techniques for tracking multiple targets in distributed sensor networks is provided and introduce some recent developments. The single target tracking in distributed sensor networks is reviewed. The tracking and resource management issues can be readily extended to MTT. The MTT problem is also briefly reviewed and describe the traditional approaches in centralized systems. Then focus on MTT in resource-constrained sensor networks and present two distinct example methods demonstrating how limited resources can be utilized in MTT applications. Finally, the most important remaining problems are discussed and suggest future directions     

目标跟踪角度标定的单目法设计

提出一种动态目标随动的目标跟踪角度标定的单目方法,建立了单目跟踪角度标定的坐标转换体系,推导出坐标转换矩阵方程.理论分析与实验结果表明,该方法计算量小,精确度高且易实现.     

分布式协作通信网络中的MAC层协议

分布式协作网络通过节点间的相互合作来达到网络资源的共享,然而如何设计高效的媒体访问控制（MAC）层协议是分布式协作通信网络中的核心问题之一。文章基于MAC层协作的动机,探讨了分布式协作网络中MAC层协议设计所面临的问题和挑战,基于近年来涌现的典型协作MAC协议和协议性能的分析,得出结论：只有全面考虑分布式网络的特点和需求,合理地设计协议的各个环节,才能使协同通信技术在分布式网络中得到更好应用。     

Distributed Differential Oscillators for Global Clock Networks

This paper presents a distributed differential oscillator global clock network where the clock capacitance is rendered resonant with a set of on-chip spiral inductors. The clock amplitude and clock phase are both uniform across the entire global distribution, making this design scalable and compatible with existing local clocking methodologies. The resonant network, combined with phase averaging of the distributed oscillator, provides high immunity to process-, voltage-, and temperature-variation-induced timing uncertainty. Measurement results from a prototype design implemented in a 0.18-$muhbox m$CMOS technology show almost an order of magnitude less jitter and power than a traditional tree-driven grid global clock distribution. On-chip measurement circuits are used to characterize the jitter on the test chip, while a simulation model is used to examine skew and higher-order resonances in the resonant clock network.     

基于JVM的分布计算在网络仿真中的应用研究

分析分式网络仿真系统的需求,给出以Java虚拟机为平台的分布计算系统的对象设计结构,并简要介绍所开发的仿真器的功能.信元中继网的初步仿真表明,采用分布式仿真方法,5台计算机协同仿真的效率可以提高70%以上.     

无线传感器网络分布式多传感器目标检测

目标检测是无线传感器网络中的一种重要应用,文中提出了一种能量有效分布式多传感器目标检测方法,该方法区别于以往的单目标方法,通过多个节点相互协作对目标进行检测,算法1给出了时间序列离散法,求得目标被测距离,且多节点将检测到的信息在聚合节点进行聚合,并通过算法2找到一条最优传输路径将聚合数据包传送至sink节点。此外通过仿真比较了单节点检测目标和多节点协同检测目标的概率、权系数α对检测节点平均能量消耗的影响,并给出了目标检测数据的最佳采样周期。     

Distributed Dynamic Backhauling in Aerial Heterogeneous Networks

Wireless Personal Communications - A Wireless Mesh Network (WMN) is a multi-hop network that gains the benefits of low deployment cost, fast access speed, expanded service coverage and large...     

Optimal Distributed Location Management in Mobile Networks

An important issue in the design of future Personal Communication Services (PCS) networks is the efficient management of location information. In this paper, we consider a distributed database architecture for location management in which update and query loads of the individual databases are balanced. We obtain lower bounds to the worst-case delay in locating a mobile user, to the average delay, and to the call blocking probability. We then propose a dynamic location management algorithm that meets these lower bounds. The optimality of this algorithm with respect to these three performance measures, as well as simplicity, make it an appealing candidate for distributed location management in PCS networks.     

MAC Protocols for Distributed Cooperative Communication Networks

Distributed cooperative networks use the cooperation among nodes to fulfill network resource sharing. However,designing an efficient Media Access Control (MAC) protocol is a key issue for the distributed cooperative network. Based on the principle of MAC-layer cooperation,this paper discusses problems and challenges for MAC protocol design in the distributed cooperative network. Through the analysis of typical cooperative MAC protocols and their performance,this paper concludes that only a reasonable MAC pr...     

Differential Distributed Space-Time Modulation for Cooperative Networks

In this paper, we develop a protocol for the construction of cooperative networks when the channel state information is not available at the transmitters and the receivers. In the proposed protocol, differential space-time codewords are generated at the source terminal. In the broadcast phase, each row of the differential space-time codeword is transmitted to a different relay, whereas in the relay phase, the relaying terminals retransmit the codeword through simple amplify-and-forward algorithm. The performance of the cooperative diversity system is analyzed for a two-user case for different channel environments in. terms of the diversity gain and the diversity product. The optimization of the power allocation between source and relay terminals is considered for the maximization of the diversity product. When the same modulation scheme is used, the performance of differential detection is degraded by 3 dB noise enhancement compared with coherent detection     

Distributed Topology Construction in ZigBee Wireless Networks

Topology control is one of the important techniques in wireless multi-hop networks to preserve connectivity and extend the network lifetime. This is more significant in ZigBee, since the address assignment scheme is tightly coupled with topology construction. For example, there can be orphan nodes that cannot receive the network address and isolated from the network due to predefined network configurations. In this paper, we propose a distributed topology construction algorithm that controls the association time of each node in order to solve the orphan node problem in ZigBee as well as construct an efficient routing tree topology. The main idea of the distributed topology construction algorithm is to construct primary backbone nodes by propagating the invitation packets and controlling the association time based on the link quality. Since the dynamically selected primary nodes are spread throughout the network, they can provide backbone to accept the association requests from the remaining secondary nodes which are majority in a network. In the performance evaluation, we show that the proposed topology construction algorithm effectively solves the orphan node problem regardless of network density as well as provides efficient tree routing cost comparable to the approximation algorithm for degree constrained minimum routing cost tree (DC-MRCT) problem.     

多层中继网络上的分布式LT码

目前对分布式LT码(DLT)的研究仅限于信源数量较少、且只有1层中继的情况,该文提出一种能够部署在多层中继网络上的分布式LT码,即多层分布式LT码(MLDLT)。该码将信源进行分组,将中继进行分层,通过分层后的中继群,可以将多达几十个乃至上百个信源连接到同一个接收端,从而实现众多信源通过多层中继对同一个接收终端的分布式LT码通信。通过对MLDLT码进行与或树分析,得出其中继度分布的线性优化方程。分别在无损和有损链路上计算该码的渐进性能并进行数值仿真,结果证明MLDLT码在无损和有损链路上的错误平台都比较低。MLDLT码非常适合于信源数量较多的多层中继网络。