预测轨迹在真实环境中的修正技术研究

在4D轨迹预测模型结果实际工程应用的过程中,总是存在飞行计划预测轨迹和雷达航迹不一致的现象,通过对模型和实际数据的分析,查找计划预测轨迹的偏离因素。该文描述了实际运行过程中涉及影响预测轨迹的各类因素,分析了数据对模型的影响;并结合分析结果提出了实施过程中对计划轨迹的修正方法,该分析结果将促进4D预测轨迹在空中交通管理领域中的实施。     

基于免疫算法的交通标志分割

针对现有道路交通标志图像分割算法中实时性和鲁棒性较差的问题,提出一种基于免疫算法和RGB颜色空间的交通标志图像分割新方法。该方法先用RGB颜色空间将交通标志从实景图中定位出来,利用免疫算法快速搜索的机理,对已定位的图像进行阈值T寻优,并用该阈值T分割图像。实验结果表明,该算法与基于遗传算法的图象分割算法相比较,具有较好的鲁棒性和实时性,且适用于不同光照条件下的交通标志图像分割。     

A NOTE ON THE INTERACTIONS OF ELEMENTARY WAVES FOR THE AR TRAFFIC FLOW MODEL WITHOUT VACUUM

In this note, we consider the interactions of elementary waves for the traffic flow model proposed by Aw and Rascle when the vacuum is not involved. The solutions are obtained constructively and globally when the initial data consist of three pieces of constant states. Furthermore, it can be found that the Riemann solutions are stable with respect to such small perturbations of the initial data in this particular situation by investigating the limits of the solutions as the perturbed parameter ε goes to zero.     

基于行为特征学习的互联网流量分类方法

基于连接图的互联网流量分类方法能反映主机间的通信行为,具有较高的分类稳定性,但是经验式总结的启发式规则有限,难以获得高分类准确率.研究分析了主机间通信行为模式和BOF方法,从具有相同{目的IP地址,目的端口号,传输层协议}网络流量中,提取主机间连接相关的行为统计特征(HCBF),采用C4.5决策树算法学习基于行为特征的分类规则,其无需人工建立启发式规则.在传统互联网和移动互联网流量数据集上,从基本分类性能和分类稳定性方面,与现有的特征集进行比较分析,实验结果表明,HCBF特征集合的类间区分能力和稳定性较高.     

改进的基于ALOHA的RFID防碰撞算法

为了解决RFID系统中电子标签识别效率不高的问题,对基于ALOHA的随机性防碰撞算法进行了详细分析,提出了一种新的ALOHA防碰撞算法.在该算法中,针对标签估计,采用动态调整的方式自动改变标签估计式中的系数,使得标签估计个数随着已识别的标签数动态变化,从而估计下一帧待识别标签数;而对于帧长调整,根据估计的标签数,通过帧长与标签数分组的关系确定.通过MATLAB进行仿真,结果表明,该算法能明显提高系统的吞吐率和稳定性.     

移动互联网业务对未来无线通信系统的影响分析

Based on the analysis of application status in real network, the trace model of some typical mobile Internet applications data is given and their impact on 2G/ 3G network is discussed in this paper. Furthermore, in order to support the mobile Internet application efficiently in future, the issues including the impact on the Long Term Evolution (LTE-A) system and some potential solutions for performance optimization are studied. Based on the trace data model of IM traffic, the performacne evaluaiton of LTE-A system shows that some specific configuration machanisms can play an important role in improving network system efficiency in the case of IM traffic.     

基于多维熵序列分类的骨干网上流量异常检测

Detecting traffic anomalies is essential for diagnosing attacks. High-Speed Backbone Networks (HSBN) require Traffic Anomaly Detection Systems (TADS) which are accurate (high detection and low false positive rates) and efficient. The proposed approach utilizes entropy as traffic distributions metric over some traffic dimensions. An efficient algorithm, having low computational and space complexity, is used to estimate entropy. Entropy values over all dimensions are collected to form a detection vector for every sliding window. One class support vector machine classifies all detection vectors into one of two groups: abnormal vectors and normal vectors. A Multi-Windows Correlation Algorithm (MWCA) calculates comprehensive anomaly scores observed in a sequence of windows in order to reduce false positive rates and obtain high detection rates. Some real-world traffic traces have been used to validate and evaluate the efficiency and accuracy of this system through three experiments. In Experiment 1, the estimating algorithm of entropy which costs less memory and runs faster than traditional algorithms is more suitable for detection anomalies. In Experiment 2, the classification and correlation algorithms can improve the detection accuracy significantly. Experiment 3 compares the subject system and three well-known systems. Ours system is the most accurate one. Those results have indicated that the proposed system significantly improves the accuracy and efficiency.     

一种新的动态流量疏导算法

文章主要研究WDM(波分复用)光网络中动态业务流量疏导的选路算法,提出了基于拓扑融合的动态流量疏导算法。该算法的最大特点在于融合了物理拓扑及其抽象出来的虚拓扑,利用最小权重优先方法进行选路。仿真结果表明,该算法在不增大建路时延的基础上,可以有效提高资源利用率,降低阻塞率,尤其是在高负载情况下,效果显著。     

一种基于聚合流的端到端统计时延界的新算法

为分析融合网络中聚合业务的端到端时延性能,提出一种基于聚合流的融合网络端到端统计时延界的新算法.该算法利用MGF(矩母函数)重新表征了网络端到端时延界的MGF形式的概率模型.数值分析结果表明了该算法的有效性和优越性,该算法很大程度上提高了独立统计复用,对融合网络性能评价具有参考意义.     

Multicast capacity of optical ring network with hotspot traffic: The bi-directional WDM packet ring

Packet-switching WDM ring networks with a hotspot transporting unicast, multicast, and broadcast traffic are important components of high-speed metropolitan area networks. For an arbitrary multicast fanout traffic model with uniform, hotspot destination, and hotspot source packet traffic, we analyze the maximum achievable long-run average packet throughput, which we refer to as multicast capacity, of bi-directional shortest path routed WDM rings. We identify three segments that can experience the maximum utilization, and thus, limit the multicast capacity. We characterize the segment utilization probabilities through bounds and approximations, which we verify through simulations. We discover that shortest path routing can lead to utilization probabilities above one half for moderate to large portions of hotspot source multi- and broadcast traffic, and consequently multicast capacities of less than two simultaneous packet transmissions. We outline a one-copy routing strategy that guarantees a multicast capacity of at least two simultaneous packet transmissions for arbitrary hotspot source traffic.