一种提高羟基分子示踪速率测量精度的方法

为了尽量减小羟基(OH)分子示踪流场速率测量误差、提高测量精度,利用OH分子标记线沿宽度方向的强度分布近似为高斯函数的特征,用高斯函数对实验测量数据进行了拟合,用拟合数据的峰值位置作为OH分子标记线的中心位置,并以此作为测量基准位置,对典型的OH分子示踪速率测量数据进行了处理.结果表明,采用这一数据处理方法,可使流场速率计算精度明显提高.     

基于滑动窗口的LRU大流检测算法

由于高速链路中的流量测量缺乏可扩展性且高速链路中及时准确的识别大流对网络测量、控制和管理有重要的意义,且在高速链路中能有效、合理的利用有限的资源,是解决资源紧缺的有效方法,基于此提出一种基于滑动窗口的资源可控的LRU淘汰机制大流量测量算法。通过"滑动窗口"机制,实现流大小的无偏估计,然后采用LRU的思想过滤小流、检测大流。仿真实验证明该算法的可行性。     

互联网智能路由架构及算法

突发流量在网络中非常普遍,会严重损害用户体验。突发流量往往能在短时间（如毫秒级别）内充满链路,导致网络拥塞和频繁分组丢失,端到端时延增加。传统路由算法要么是流量无关（如 OSPF（open shortest path first,开放式最短路径优先））的,无法对实时流量的变化做出调整;要么是集中式控制的（如线性规划）,面临求解时延过大而无法有效应对突发流量的问题。提出了一种新的智能路由算法解决突发流量的问题。一方面,提出的算法能利用机器学习强大的建模能力,通过对网络历史数据的挖掘来学习“隐式”的路由决策依据。另一方面,提出的算法能借助机器学习的快速推理能力降低决策时延,提高系统对突发流量的响应速度。实验结果表明,在真实流量数据集下,相比较其他路由算法,提出的智能路由算法能降低13%～70%的瓶颈链路利用率。     

基于手机信令的城市道路交通状态实时预测

为准确、实时预测道路交通状态,通过分析影响交通的因素,利用决策树算法对速度和环境因素等数据进行建模,确定交通拥堵发生的规则,在此基础上结合实时的移动用户和环境因素数据对交通状态进行预测。以中国河北保定城区为例进行实验,验证了该方法的有效性。同时,研究发现,基于决策树算法进行道路交通状态预测的方法具有较好的扩展性。     

基于四旋翼飞行器的改进金字塔LK光流算法的研究

针对四旋翼飞行器在飞行过程的水平漂移问题,提出利用改进的金字塔LK光流算法予以改善.首先,通过VisualStudio2013仿真,确知改进的金字塔LK光流算法比传统金字塔LK光流算法对图像的速度信息提取精度更高.然后,再建立四旋翼飞行器的动力学模型,将两种光流算法导入MATLAB的仿真模型中,得出:四旋翼飞行器能有效根据改进的金字塔LK光流算法获得速度信息以降低水平漂移.最后,通过在轴距为430 mm的四旋翼飞行器的平台上进行飞行试验,结果表明:采用改进的金字塔LK光流算法能使四旋翼飞行器的水平漂移程度降低,可实现较为稳定的悬停.     

Packet‐level‐based traffic aggregation to optimize NDN content delivery

In recent years, named data networking (NDN) has been accepted as the most popular future paradigm and attracted much attention, of which the routing model contains interest forwarding and content delivery. However, interest forwarding is far from the bottleneck of routing optimization; instead, the study on content delivery can greatly promote routing performance. Although many proposals on content delivery have been investigated, they have not considered packet‐level caching and deep traffic aggregation, which goes against the performance optimization of content delivery. In this paper, we propose a packet‐level‐based traffic aggregation (PLTA) scheme to optimize NDN content delivery. At first, the packet format is devised, and data plane development kit (DPDK) is used to ensure same size for each packet. Then, the whole delivery scheme with traffic aggregation consideration is presented. The simulation is driven by the real YouTube dataset over Deltacom, NSFNET, and CERNET topologies, and the experimental results demonstrate that the proposed PLTA has better delivery performance than three baselines in terms of cache hit ratio, delivery delay, network load, and energy efficiency.     

A network traffic prediction model of smart substation based on IGSA‐WNN

The network traffic prediction of a smart substation is key in strengthening its system security protection. To improve the performance of its traffic prediction, in this paper, we propose an improved gravitational search algorithm (IGSA), then introduce the IGSA into a wavelet neural network (WNN), iteratively optimize the initial connection weighting, scalability factor, and shift factor, and establish a smart substation network traffic prediction model based on the IGSA‐WNN. A comparative analysis of the experimental results shows that the performance of the IGSA‐WNN‐based prediction model further improves the convergence velocity and prediction accuracy, and that the proposed model solves the deficiency issues of the original WNN, such as slow convergence velocity and ease of falling into a locally optimal solution; thus, it is a better smart substation network traffic prediction model.     

两相旋流分离器矿浆内部流场及分离特性研究

利用两相旋流分离器可以实现矿浆的浓缩和液体澄清。为探索两相旋流分离器内部流场及分离特性,文中通过CFD软件Fluent,采用RNG k-ε湍流模型,对两相旋流分离器内部的三维流场进行数值模拟,得出了压力、速度、体积分布、湍流动能和湍流耗散率等参数的分布情况。结果表明,两相分离旋流器内部径向速度由中心沿径向外逐渐增大,离近分离器壁时又逐渐降低,呈现出“M”型驼峰分布。轴向速度呈对称分布,最大值出现在顶部溢流口和底流口。从矿粒和水在旋流器内部的流动轨迹可以看出,矿浆浑浊液从切向进口进入旋流分离器后,矿粒和水在旋流分离器内部作高速旋转运动,形成外旋流和内旋流。密度较重的矿粒从下部底流口流出,密度较轻的水从上部溢流口流出,模拟两相分离效率可达到86.93% 。     

Distributed interference coordination based on multi-agent deep reinforcement learning

A distributed interference coordination strategy based on multi-agent deep reinforcement learning was investigated to meet the requirements of file downloading traffic in interference networks.By the proposed strategy transmission scheme could be adjusted adaptively based on the interference environment and traffic requirements with limited amount of information exchanged among nodes.Simulation results show that the user satisfaction loss of the proposed strategy from the optimal strategy with perfect future information does not exceed 11% for arbitrary number of users and traffic requirements.     

基于OPNET Modeler的UMTS性能分析仿真平台

随着计算机性能和仿真技术的提高,计算机仿真技术得到越来越广泛的运用.OPNET是一种具有高可靠度的网络建模、设计、仿真和分析工具.文中主要介绍了基于OPNET建立的UMTS仿真平台,并基于该平台研究了UMTS网络典型业务端到端的关键性能参数,以及根据业务服务质量的需求提供不同等级服务的可行性.仿真结果表明,该系统级仿真平台对UMTS系统的性能分析是有效的,为网络的规划设计提供客观、可靠的定量依据.