RMTP协议的时延分析

RMTP(reliable multicast transport protocol)是一种通过修复服务器(repair server)本地恢复来提供可靠性的组播协议.对改进的RMTP协议的时延性能进行建模分析.推导了数据包自发送主机发出到成功地被一个随机选择的接收主机接收之间的平均时延公式.分析表明,随着丢失率的增长,RMTP的时延性能恶化点将迅速下降;随着每个修复服务器下连接尾链路数量的增加,RMTP的时延性能恶化点也将下降.但是,随着尾链路总数量的增加而保持每个修复服务器连接的尾链路数量不变,RMTP的时延性能的变化很小.仿真结果较好地验证了分析的有效性.     

单调矩阵搜索算法设计与应用

本文提出了单调矩阵搜索问题一个统一的算法框架和实现策略，使得可在线性时间内求得矩阵搜索问题的解，并将此算法框架应用于设计凸多边形所有顶点最远邻点问题的高效算法。     

Optimal Routing Designs in Self-healing Communications Networks

Self-healing communication networks that allow re-routing of demands through switching processes at designated nodes are studied. It is shown how network utilization, demand throughput and reliability of such networks can be studied simultaneously to achieve an optimal design for all three. This is done through a max–min–max multi-commodity network flow formulation of the routing problem in which it is ensured that maximum network throughput is achieved with minimum loss of demands that are blocked due to single switching node failures. It is shown that a node-path linear programming approximation to the multi-commodity network flow formulation solves the problem for medium and large network sizes in moderate computational times.     

Remote sensing support for national forest inventories

National forest inventory programs are tasked to produce timely and accurate estimates for a wide range of forest resource variables for a variety of users and applications. Time, cost, and precision constraints cause these programs to seek technological innovations that contribute to measurement and estimation efficiencies and that facilitate the production and distribution of an increasing array of inventory data, estimates, and derived products. Many of the recent innovations have involved remotely sensed data and related statistical estimation techniques. Current applications of remote sensing in support of national forest inventories are reviewed for three areas: (1) observation or measurement, meaning using remotely sensed data in lieu of field observations or measurements; (2) estimation, meaning calculation of traditional inventory areal estimates such as forest area or volume per unit area; and (3) mapping. Future applications focus on two areas: augmenting field measurements with remotely sensed data obtained from lidar sensors and Internet accessible map-based estimation.     

实现电力监控嵌入式系统可靠数据交换的串行通信Agent

基于任务Agent的设计理念,开发了一种实现电力监控嵌入式系统可靠数据交换的串行通信Agent模块。这种模块实现了串行通信的全程代理。采用这种模块的嵌入式系统,只要对接口的双口RAM进行访问即可完成不同系统间的可靠数据交换,从而使串行通信变得非常方便且更加可靠。同时,采用这种模块还能有效地缩短产品的开发周期。详细地介绍了这种串行通信Agent模块的设计思想、基本原理和实现方法。     

MPE2S: 基于多路径纠删编码的无线传感器网络可靠传输策略

传输可靠性是衡量无线传感器(Wireless sensor networks, WSN)网络性能的一个重要指标. 针对节点故障会影响网络传输稳定性和可靠性的问题, 提出了基于多路径纠删编码的 无线传感器网络可靠传输策略(Multi-paths and erasure encoding strategy, MPE2S). 根据反映链路质量的最优最差蚂蚁系统的信息素归一化值, 在相邻等级节点间建立多条互不交叉的传输路径, 将源数据包经纠删编码的 数据片沿多条路径分配和传输以实现负载均衡和故障容错. 理论分析和仿真结果表明,MPE2S具有较高数据包接收率、数据准确率和能效性, 体现了良好的故障容错性、数据传输稳定性和可靠性.     

基于独立成分分析的含噪声时间序列预测

提出一种基于独立成分分析(ICA)的最小二乘支持向量机(LS-SVM),用于时间序列的多步超前独立预测.用ICA估计预测变量中的独立成分(IC),用不含噪声的IC重新构建时间序列.利用 -最近邻法( -NN)减小训练集的规模,提出一种新的距离函数以降低LS-SVM训练过程的计算复杂度,并用约束条件对预测值进行后处理.使用基于ICA的LS-SVM、普通LS-SVM与反向传播神经网络(BP-ANN),对多个时间序列进行对比预测实验.实验结果表明,基于ICA的LS-SVM的预测性能优于普通LS-SVM和BP-ANN.     

Delay-dependent reliable H ∞ filtering for sector-bounded nonlinear continuous-time systems with time-varying state delays and sensor failures

In this article, the reliable H _∞ filtering problem against sensor failures is investigated for a class of continuous-time systems with simultaneous sector-bounded nonlinearities and varying time delays. The focus of this article is on designing a reliable filter such that the filtering error system is asymptotically stable and meets the prescribed H _∞ norm constraint in the normal case as well as in the sensor failure case simultaneously. Linear matrix inequality conditions, which depend not only on the upper and lower bounds of delay but also on the upper bound of delay derivative, are obtained for the existence of admissible filters and, based on these, the filter design is cast into a convex optimisation problem. What is worth mentioning is that the information about the upper bound of the delay derivative is taken into consideration even if this upper bound is not smaller than 1. A numerical example is presented to illustrate the effectiveness and advantage of the developed filter design method.     

Classification of weld flaws with imbalanced class data

This paper presents research results of our investigation of the imbalanced data problem in the classification of different types of weld flaws, a multi-class classification problem. The one-against-all scheme is adopted to carry out multi-class classification and three algorithms including minimum distance, nearest neighbors, and fuzzy nearest neighbors are employed as the classifiers. The effectiveness of 22 data preprocessing methods for dealing with imbalanced data is evaluated in terms of eight evaluation criteria to determine whether any method would emerge to dominate the others. The test results indicate that: (1) nearest neighbor classifiers outperform the minimum distance classifier; (2) some data preprocessing methods do not improve any criterion and they vary from one classifier to another; (3) the combination of using the AHC_KM data preprocessing method with the 1-NN classifier is the best because they together produce the best performance in six of eight evaluation criteria; and (4) the most difficult weld flaw type to recognize is crack.     

CORDIC Processor for Variable-Precision Interval Arithmetic

In this paper we present a specific CORDIC processor for variable-precision coordinates. This system allows us to specify the precision to perform the CORDIC operation, and control the accuracy of the result, in such a way that re-computation of inaccurate results can be carried out with higher precision. It permits a reliable and accurate evaluation of a wide range of elementary functions. The specific architecture designed greatly improves the computational time of previous solutions based on classic polynomial approximation. For controlling error in numerical computation (where intervals are normally narrow) the proposed design performs an interval operation in a time close to that of a point operation.