低轨电磁监测智能处理框架与关键技术综述

依托低轨星座构建电磁频谱监测系统成为实现全球电磁频谱管理的有效途径与当前的研究热点.传统低轨电磁监测系统架构采用“星上采集与处理”的模式,即卫星对信号进行采集并处理后,将处理的结果回传到地面.这导致系统性能受限于单星载荷.针对此问题提出采集与处理分离的低轨电磁监测系统智能处理框架,卫星作为数据的转发节点,仅负责采集信号,地面数据中心对数据进行下一步处理.同时,针对传统技术方法难以高效处理该架构下地面数据中心海量数据的问题,将深度学习与传统架构下的关键技术进行了有机融合,为实现全球时空连续电磁频谱监测提供了新的选择.梳理了基于深度学习的频谱感知、盲源分离和无源定位三大关键技术及其近几年研究进展;重点讨论了各关键技术向星座系统迁移的适用性问题与技术核心突破问题,给出了低轨电磁监测系统智能处理框架中关键技术的下一步研究建议.     

基于危险天气不确定性的最小风险路径规划方法

为降低飞行过程中遭遇危险天气的概率,同时避免大范围绕飞导致的路径与耗油增加,针对航路中的雷暴、积冰和颠簸天气,使用数值预报和概率预报,面向航前飞行计划,提出一种基于危险天气不确定性的最小风险路径规划方法.首先,基于概率预报数据使用配料法和C-F模型计算雷暴发生概率,基于数值预报数据计算积冰预测指数和颠簸预测指数;然后,融合多类型危险天气,提出一种具备风险标识的栅格化地图;在此基础上,改进传统路径最短的规划算法,构建以风险最小化为目标的Dijkstra和A*算法;最后,使用2023年4月3日华中地区强对流天气预测数据建立风险地图,使用上述改进算法与传统Dijkstra、A*和RRT算法进行路径规划并对比分析.结果表明,传统Dijkstra和A*算法可计算得到最短飞行路径,而改进的A*算法可计算得到总风险最小路径;若综合考虑飞行风险与路径长度,改进的Dijkstra算法最为适合.     

一种基于链路质量的选择协作式HARQ传输协议

针对单中继协同混合自动重传请求(hybrid automatic repeat request,HARQ)策略中重传时延性能不佳的问题,通过对快衰落信道下单中继HARQ系统的误码率和时延特性的研究和分析,提出一种基于目的端控制选择协作式HARQ(selective cooperative-HARQ,SC-HARQ)传输协议的实现方案,此方案是在单中继环境下根据中继链路和直达链路的链路质量判断选择重传路径的HARQ传输协议.SC-HARQ传输协议方案需要设定传输链路质量的门限值,然后根据不同的链路质量选择不同的重传模式:当直达链路质量大于设定的门限值时,选择直达链路进行重传;反之,选择完全协同HARQ传输协议进行重传.经过理论分析和MATLAB仿真验证证明,SC-HARQ传输协议方案在保证一定传输质量的前提下能够有效减小系统时延、改善系统性能.     

联合改进作用距离和Dijkstra算法的复杂结构声发射定位方法及应用

声发射定位对含空区等复杂结构的连续动态安全监测具有重要意义。针对直线路径定位方法不适用于复杂结构,而常规Dijkstra搜索算法常出现局部最优路径等问题,提出了一种联合改进作用距离和Dijkstra算法的声发射定位方法,实现复杂结构下声发射的高精度定位。理论测试显示：基于改进作用距离的Dijkstra算法得到的P波传播路径长度小于等于常规作用距离的Dijkstra算法,即P波走时更为准确。理论测试和断铅试验定位测试表明：本文提出的定位方法在复杂结构声发射定位时的整体误差在0.50 cm范围之内,断铅事件平均定位误差由常规作用距离Dijkstra算法的0.95 cm下降至本文的0.54 cm。改进的声发射定位方法在复杂结构声发射定位方面具有很好的应用前景。     

WSN中的路由洞避开机制

贪婪路由选择算法是一种简便高效的路径建立算法,它建立的路径具有非常好的方向性和最优性,是无线传感器网络中基于地理位置的路由算法中非常重要的算法之一,但是,这种算法遭遇到路由空洞问题的可能性比较大.研究了一种路由洞避开机制,仿真结果表明:算法在保证良好的路由方向性的基础上还可以很好地避开路由洞,不仅增加了网络的存活时间,还特别适合应用在异构网络中.     

基于PSO的Live Wire交互式图像分割算法

传统Live Wire算法易受伪轮廓干扰,并且算法执行速度较慢.针对这些问题,提出一种基于PSO的Live Wire交互式图像分割算法.算法首先构造新的代价函数,引入相邻节点间梯度幅值变化函数来减轻伪轮廓的干扰,提高了算法的分割精度;其次,为了提高算法的执行效率,应用粒子群算法求取图像中任意两点间最短路径来定位目标边界,并与经典的基于Dijkstra动态规划图搜索的Live Wire算法进行比较.实验结果表明,与传统方法相比,所提算法在分割精度和执行效率上都有很大提高.     

重大事故救灾路线双目标优化模型及算法

运用运筹学的理论和方法,建立一种重大事故救灾路线双目标优化数学模型.基于启发式算法思想,提出适合该模型且收敛速度较快的优化算法.该算法通过构造辅助函数调用Dijkstra算法,在最优解的近似区间内多次迭代逐渐逼近最优解,实现了双权重网络图最短路的求解,是一种近似的、快速的算法.基于所构造辅助函数的性质,给出实现该算法的具体步骤.对误差进行线性估计,分析了该算法收敛速度的影响因素,并讨论了算法的时间复杂度及优势.最后在案例分析中编译并运行该算法,证实其模拟结果与理论分析结论相吻合.      

基于带宽与往返时间联合预测的多路径并行传输性能优化算法

在流控传输协议(stream control transmission protocol,SCTP)中,多路径并行传输利用多家乡特性实现数据在关联的多条端到端路径中的并行传输.然而,受不同路径性能差异的影响,多路径并行传输将带来接收端的数据乱序.为了减轻数据乱序的程度并提高网络吞吐量性能,需要尽可能准确地估计每条路径的实时带宽与往返时间(round trip time,RTT).本文利用扩展矢量卡尔曼滤波对多路径并行传输中每条路径的可用带宽与往返时间进行联合预测,同时提出了一种综合考虑发送端未经接收端确认的数据的路径选择算法.仿真结果表明,通过实时准确地预测可用带宽和往返时间,路径选择算法能够减轻接收端数据乱序的程度.对于带宽敏感的多路径应用场景而言,该算法的收敛速度比Kalman-CMT算法更快,对网络吞吐量性能也有一定程度地提高;对时延和带宽都敏感的多路径应用场景来说,算法在收敛速度与吞吐量两方面优势明显.      

Mallat小波快速变换与IDRNN在卫星实时故障检测与识别中的应用

系统研究了面向复杂系统监测时变信号的实时故障检测与识别问题.采用滑窗Mallat小波快速变换克服传统小波变换的时域全局依耐性并提高计算效率,使之适应于实时故障检测;针对时变信号的故障模式识别难题,在故障检测基础上采用改进动态循环神经网络(improved dynamic recurrent neural network,IDRNN)进行智能故障识别.最后将滑动时窗小波检测模块及最优IDRNN网络模块嵌入某型完整卫星姿态控制系统仿真平台进行在线故障诊断.试验结果表明:实时条件下的滑动窗口小波变换与传统小波变换具有一致性,IDRNN对于时变信号识别具有较好的时域泛化能力,将滑窗移动时不变小波方法与IDRNN结合可以实现面向复杂系统监测实时信号的故障检测及复合模式分类.      

基于按需和贪婪转发的移动自组网路由协议

移动自组网的动态拓扑特性给路由协议的设计带来了一定的挑战,尤其是在高动态的网络环境中.本文针对该问题,提出了一种新的基于按需和贪婪转发的路由协议,该协议是在RGR模式的基础上提出以下三点改进,即:（1）通过受限的洪泛机制降低网络在路由发现阶段的控制开销;（2）通过移动预测机制,在被动寻路阶段监视被动路径的状态和在GGF阶段帮助节点选取适当的邻居作为下一跳节点;（3）通过路径请求延迟机制以减少不必要的资源浪费.仿真结果表明:改进的RGR协议与现有的RGR、AODV、Modified-RGR和Optimized-RGR相比,不仅具有较高的数据包接收成功率,而且平均路由开销和端到端时延也相对较低.      

Efficient Algorithm for Gradually Varied Flows in Channel Networks

This paper presents an efficient solution technique for one-dimensional unsteady flow routing through a general channel network system—dendritic, looped, divergent, or any combination of such networks. The finite difference method is used to solve the de St. Venant equations in all the branches of the network simultaneously. The number of equations to be solved at a time during any iteration is reduced to only four times the number of branches of the network. This results in a significant reduction in storage requirements and solution time. Importantly, the algorithm does not require any special node numbering schemes and the nodes can be numbered independently for each branch. The algorithm is also suitable for programming on a parallel-processing computer.     

一种改进的Ad Hoc网络路由协议AODV-DD

针对AODV路由协议进行本地修复时存在节点移动剧烈区域本地修复重复发生和本地修复没有考虑已存在下游链路的问题,提出一种新的带决策的双向修复AODV路由协议（AODV—DD）,新协议对AODV的本地修复算法进行了改进,根据节点本地修复次数对是否发生本地修复进行决策,并且在修复时进行双向修复的算法优化。NS2中的仿真实验表明,改进本地修复算法后的路由协议性能有了一定的提升,尤其在时间延迟方面有较大的改进。     

A Potts Neuron Approach to Communication Routing

A feedback neural network approach to communication routing problems is developed, with emphasis on multiple shortest path problems, with several requests for transmissions between distinct start and end nodes. The basic ingredients are a set of Potts neurons for each request, with interactions designed to minimize path lengths and prevent overloading of network arcs. The topological nature of the problem is conveniently handled using a propagator matrix approach. Although the constraints are global, the algorithmic steps are based entirely on local information, facilitating distributed implementations. In the polynomially solvable single-request case, the approach reduces to a fuzzy version of the Bellman-Ford algorithm. The method is evaluated for synthetic problems of varying sizes and load levels, by comparing to exact solutions from a branch-and-bound method, or to approximate solutions from a simple heuristic. With very few exceptions, the Potts approach gives high-quality legal solutions. The computational demand scales merely as the product of the numbers of requests, nodes, and arcs.     

Computing Travel Time Reliability in Transportation Networks with Multistates and Dependent Link Failures

The measurement of transportation network travel time reliability is imperative to provide drivers with accurate route guidance information and to generate the shortest path (or alternative paths) connecting origins and destinations, especially under conditions of varying demands and limited capacities. Previous studies assumed that link failures in a road network are statistically independent and that reliability probabilities are perfectly determinable. In real life, these assumptions are dubious, because the failure of a link in one particular area does not necessarily result in the complete failure of the neighboring link, but may lead to deterioration of its performance. This paper presents a new methodology to study the multistate system reliability analysis of transportation networks for which one cannot formulate an “all or nothing” type of failure criterion and in which dependent link failures are considered. The methodology is presented, using a numerical example, for computing the probability that travel time between an origin and a destination may exceed a threshold.     

矿井火灾最优逃生路径优化数学模型的构建与实现

最优应急避灾路线的确定是安全有效逃生的第一步。针对井下实际应急逃生情况的需要,定义了矿井火灾三大避险原则,对通行路径的安全系数进行量化分析并提出了行进速度影响因子的计算方法,结合巷道安全系数与行进速度影响因子构建了巷道逃生路径优化数学模型。根据巷道当量长度计算公式,将井巷网络图转换为巷道当量网络图,在此网络图的基础上通过Dijkstra算法求解人员位置点到安全点的最短路径,从而确保逃生路径的安全与快捷。最后,将模型应用到云南某金属矿山,为矿井火灾辅助逃生系统提供借鉴与技术支持。     

雷暴天气下的多航班备降动态优化方案

空中多次备降极易导致低油量等不安全事件发生。针对区域内多航班集体备降这一问题，选取其中最复杂情况，即航路或终端区存在雷暴天气，首先通过搜集和统计气象数据与历史航迹，得到雷暴天气下飞行限制区的划设标准；然后，将前往备降场方式分为机动飞行与沿航路飞行两类，分别使用A*与改进灰狼?Dijkstra方法开展改航路径规划；先以备降航班飞行总时长最短为单目标，再综合飞行、管制、机场、航空公司等多方期望构建多目标函数，定义动态决策时间间隔，提出一种基于单目标与多目标的区域内多航班备降动态优化方案；最后，使用“8.12”华北运行数据开展仿真验证，在单目标与多目标方案中，面向机动飞行A*算法所得结果分别将飞行总时长减少了100 min和62 min，而面向按照航路飞行的改进灰狼?Dijkstra算法所得总时长分别减少73 min和14 min；并且，在多目标方案中，航班恢复飞往原目的地的时间整体提前了63 min，总成本降低了6.29万元。以上说明，该方案在保证航班备降安全基础上，可兼顾多方需求，提升经济与效率。      

Intelligent Multivariable Modeling of Blast Furnace Molten Iron Quality Based on Dynamic AGA-ANN and PCA

Blast furnace(BF)ironmaking process has complex and nonlinear dynamic characteristics.The molten iron temperature(MIT)as well as Si,P and S contents of molten iron is difficult to be directly measured online,and large-time delay exists in offline analysis through laboratory sampling.A nonlinear multivariate intelligent modeling method was proposed for molten iron quality(MIQ)based on principal component analysis(PCA)and dynamic genetic neural network.The modeling method used the practical data processed by PCA dimension reduction as inputs of the dynamic artificial neural network(ANN).A dynamic feedback link was introduced to produce a dynamic neural network on the basis of traditional back propagation ANN.The proposed model improved the dynamic adaptability of networks and solved the strong fluctuation and resistance problem in a nonlinear dynamic system.Moreover,a new hybrid training method was presented where adaptive genetic algorithms(AGA)and ANN were integrated,which could improve network convergence speed and avoid network into local minima.The proposed method made it easier for operators to understand the inside status of blast furnace and offered real-time and reliable feedback information for realizing close-loop control for MIQ.Industrial experiments were made through the proposed model based on data collected from a practical steel company.The accuracy could meet the requirements of actual operation.     

Layout Design of Irrigation Networks in Highly Parcelled Territories Using Geographical Information System

Traditional irrigation zones in the east of Spain have been denoted by the high level of parcellation. The layout of the irrigation network design in highly parcelled territories presents an important degree of difficulty, the previous experience of the designer in this task being crucial in the final result. In this work, a new heuristic algorithm for layout of the irrigation network design is presented. We start from a classical graph theory algorithm (Dijkstra’s algorithm) used for solving the shortest path spanning tree problem. This algorithm is modified to assign weights to the arcs and plot limits are used as if they were the arcs of a graph. The algorithm is implemented on a geographical information system, thus creating an application that automatically generates the layout of the irrigation network design. The only necessary initial data are the origin of the network (supply point) and the hydrants (delivery points). The advantage of this heuristic is that the subjectivity introduced for the designer is removed. Moreover, it allows for solving complex problems, and therefore it is applicable to highly parcelled zones, where the number of vertices and edges is so high that it would inhibit calculating capacity of any optimization process. A practical example is presented, in which the layout design obtained by applying the heuristic is compared with the original existing layout.