基于固定优先级和贪心法的航班时隙分配算法

航班时隙分配在空中交通管理领域中有着重要应用,考虑到在相同的延误时间情况下,不同类型的航班和不同的载客人数造成的综合损失差异,提出一种基于贪心法的航班分配算法。该算法在对航班进行排序的时候,在考虑到航空公司公平性的基础上,根据航班类型和载客数量,计算每架航班的优先级,然后根据当前可用时隙,以贪心法的规则找出优先级最高的航班,若有多个航班满足条件,则根据先来先服务原则进行选择,从而使经济损失和人员延误损失二者构成的综合损失最小化。算法仿真结果显示：该算法在很大程度上改进机场的运营效率,确保航空公司航班分配的公平性,维护航空公司及其服务对象的利益,具有一定的实用性和有效性。     

一种改进的多机场地面等待启发式算法

从满足航空公司关于航班公平性的需求出发,将航班时刻优先规则用于改进基于优先级的多机场地面等待启发式算法(ABG算法).采用被动优先级表,根据航班计划到达时刻的先后,依次分配降落时刻,分配后的降落时刻不再参与试图降低总延误时间的时刻交换处理.基于相同实验数据的计算结果对比表明,改进算法可降低最大延误时刻的50%和输出更为平滑的航班延误分布.     

一种改进的多机场地面等待启发式算法

从满足航空公司关于航班公平性的需求出发，将航班时刻优先规则用于改进基于优先级的多机场地面等待启发式算法（ABG算法）。采用被动优先级表，根据航班计划到达时刻的先后，依次分配降落时刻，分配后的降落时刻不再参与试图降低总延误时间的时刻交换处理。基于相同实验数据的计算结果对比表明，改进算法可降低最大延误时刻的50％和输出更为平滑的航班延误分布。     

基于优先级的CHOKe算法仿真与性能分析

为将区分服务(DiffServ)网络架构中的优先级服务与网络拥塞控制相结合,提出一种应用于DiffServ架构核心路由器的CHOKe算法(CHOKeW)。针对不同优先级别的数据流进行带宽分区,为高优先级的数据流分配高带宽,并且当发生网络拥塞时通过限制高速非响应流占用的带宽,达到保护响应流的同时兼顾相同优先级数据流公平性的目的。实验使用NS-2建立仿真模型,分析CHOKeW算法、加权公平队列算法、RIO算法的不同优先级混合流的带宽公平分配情况,结果表明,CHOKeW算法能够有效提高网络性能,保证网络服务质量,并且较好地解决基于公平性和优先级的带宽分配问题     

基于两次应用优先级的GDP时隙分配算法模型

地面等待策略是空中交通流量管理中主要采用的一种方法,文中主要介绍了基于两次应用优先级的GDP时隙分配算法。初次优先级的使用是达到分组的目的,再次应用优先级则是为了解决初次分配后可能存在的在同一分组中航班竞争同一时隙的问题。文中对相应的算法实现做了详细介绍,并对成都双流机场的航班进行了多次仿真实验。同时和单纯的基于优先级的方法进行了对比,验证了该算法的可行性。     

基于两次应用优先级的GDP时隙分配算法模型

地面等待策略是空中交通流量管理中主要采用的一种方法,文中主要介绍了基于两次应用优先级的GDP时隙分配算法。初次优先级的使用是达到分组的目的,再次应用优先级则是为了解决初次分配后可能存在的在同一分组中航班竞争同一时隙的问题。文中对相应的算法实现做了详细介绍,并对成都双流机场的航班进行了多次仿真实验。同时和单纯的基于优先级的方法进行了对比,验证了该算法的可行性。     

航路资源协同分配的多目标优化方法研究

目前,航班飞行需求激增和恶劣天气已经严重影响到航空空域的正常运行,为此针对空域拥堵时航路的时隙航迹资源协同分配进行了研究.根据问题的数学描述,以总延误成本最低和公平损失偏差系数最低为两个目标,建立了航路资源协同分配模型,运用多目标遗传算法(NSGA-Ⅱ)对模型求解分析.通过航路网络的典型数据测试该模型,生成了可供决策者选择的帕累托最优解集,并与传统RBS算法进行比较,实现平均延误成本降低8.5％,平均公平损失偏差系数降低70.6％.结果 证明NSGA-Ⅱ算法可以较好的解决航路资源协同分配的问题.     

基于反馈的区分服务网络拥塞管理方案研究

为了有效解决RED算法拥塞响应滞后以及在聚集类之间公平性不足的问题,提出建立一种基于早期拥塞指示反馈的区分服务网络模型,并在该模型上采用优先级早期随机检测算法。在网络入口节点对分组进行分类、聚集与监测,各队列按优先级设置不同队列长度阈值,当平均队列长度或各队列长度达到相应阈值范围时,立即触发不同程度拥塞指示包向源端反馈。使用改进的NS进行了仿真实验,实验结果表明该算法使得拥塞指示能尽可能快地到达TCP源,有效地降低路由器中的丢包率。提高网络利用率,并且为不同的聚集类提供不同优先级服务,保障了聚集类的公平性。     

异构无线网络中动态优先级接纳控制算法研究

针对在应急情况下的异构网络环境中不同类型业务在群组切换时出现的网络拥塞问题,以及现有研究中较少考虑不同类型用户所进行的业务的重要性和紧急性不同,从而不能合理分配有限的网络资源的情况,提出了一种异构无线网络中动态优先级接纳控制算法。首先,根据用户类型和业务类型对业务设定初始优先级;然后,根据业务的执行紧迫性和业务的剩余价值密度对业务优先级进行动态调整,并提出了一种基于业务优先级的抢占调度算法;最后为避免在业务优先级进行动态调整过程中出现颠簸调度现象,给出了避免颠簸调度的条件。所提算法考虑了实际情况中不同用户类型所进行的业务重要程度的不同,对业务进行了优先级设定,使初始优先级高的业务能够优先得到服务,在此基础上为尽量满足整体用户的用网需求,对业务的优先级进行了动态调整。为验证所提方法的有效性,将基于优先级队列调度算法和基于阻塞率约束的群组切换方法作为对比算法,在MATLAB软件环境下进行仿真分析。结果表明,所提方法相较于对比算法能够在减少业务切换的阻塞率的同时,使总体业务的完成率提高10%左右,证明了该算法在使初始优先级高的业务能够优先得到服务的同时,为初始优先级低的业务提供了网络切换的条件,从而提高了网络资源分配的合理性和公平性。     

基于优先级的TDMA动态时隙分配算法

根据帧结构的不同对现有的时隙分配算法进行分类,分析其特点及综合性能。根据二叉树块内均分法,提出一种改进的时分多址动态时隙分配算法,地面主控站可根据用户的紧急或优先级高低的预约请求进行实时分配,能满足用户占用时隙块发送较长报文的需求。仿真结果表明,该算法能减少报文的平均延误时间,适合突发应急报文的传输需要。     

考虑随机因素影响的区域管制下流量动态分配

区域管制区域内的飞行流量受多种因素影响,从而容易造成航路拥堵,导致航班延误。综合考虑危险天气、航段容量、军航活动这三个主要因素,结合空域灵活使用这一理念,对飞行流量进行实时动态分配并以最小运行成本建立规划模型,通过Floyd算法求出经过该区域的所有航班的最短路径,并用matlab进行仿真计算,仿真结果表明,对流量进行动态分配后的运行成本得到有效降低,在一定程度上缓解了航路拥挤。     

A multiagent approach to managing air traffic flow

Intelligent air traffic flow management is one of the fundamental challenges facing the Federal Aviation Administration (FAA) today. FAA estimates put weather, routing decisions and airport condition induced delays at 1,682,700 h in 2007 (FAA OPSNET Data, US Department of Transportation website, ), resulting in a staggering economic loss of over $41 billion (Joint Economic Commission Majority Staff, Your flight has been delayed again, 2008). New solutions to the flow management are needed to accommodate the threefold increase in air traffic anticipated over the next two decades. Indeed, this is a complex problem where the interactions of changing conditions (e.g., weather), conflicting priorities (e.g., different airlines), limited resources (e.g., air traffic controllers) and heavy volume (e.g., over 40,000 flights over the US airspace) demand an adaptive and robust solution. In this paper we explore a multiagent algorithm where agents use reinforcement learning (RL) to reduce congestion through local actions. Each agent is associated with a fix (a specific location in 2D space) and has one of three actions: setting separation between airplanes, ordering ground delays or performing reroutes. We simulate air traffic using FACET which is an air traffic flow simulator developed at NASA and used extensively by the FAA and industry. Our FACET simulations on both artificial and real historical data from the Chicago and New York airspaces show that agents receiving personalized rewards reduce congestion by up to 80% over agents receiving a global reward and by up to 90% over a current industry approach (Monte Carlo estimation).     

Highest Urgency First (HUF): A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations

The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for mobile wireless networks. However, the link quality is frequently unstable owing to mobility and air interference and therefore impacts the latency requirement of real-time applications. In the WiMAX standard, the modulation/coding scheme and the boundary of uplink/downlink sub-frames could be adjusted subject to channel quality and the traffic volume, respectively. This provides us a chance to design a MAC-layer uplink/downlink bandwidth allocation algorithm that is QoS/PHY-aware.This work takes into account the adaptive modulation and coding scheme (MCS), uplink and downlink traffic volume, and QoS parameters of all five defined service classes to design a bandwidth allocation algorithm that calculates the slot allocation in two phases. The first phase decides the boundary of uplink and downlink sub-frames by satisfying requests with pending latency violation and proportionating according to traffic volume, while the second phase allocates slots to mobile stations considering urgency, priority and fairness. Simulation results show our algorithm achieves zero latency violation and higher system throughput compared to existing non-QoS/PHY-aware or less-QoS/PHY-aware approaches.     

无线区域网中保障QoS的多业务调度算法

针对无线区域网中多业务资源分配和调度问题,基于认知无线电的特点提出一种改进的调度算法.该算法通过计算单用户不同业务的QoS优先级,并兼顾多用户之间的公平性选择业务传输的最优信道,在传输过程中采用节点中断管理方式动态修正业务的QoS优先级.仿真结果表明,该算法能有效利用网络带宽,并且能保障单用户业务的QoS要求和多用户调...     

DiffServ网络中基于流量负载的动态带宽分配

在DiffServ网络中,流量以聚集类的形式存在,聚集类中的流量负载是随时间不断地发生动态变化的.当不同聚集类中的流量负载与调度算法(如WFQ)为其分配的资源(如带宽)不成比例时,即使两个聚集类的优先级相同,它们中的数据包也会得到不公平的待遇.为此,DiffServ网络中面向公平的动态带宽分配引起了广泛的研究.本文中为了实现公平的带宽分配,提出了一种基于流量负载的动态带宽分配的方法,其中在动态计算各个聚集类应分得的新带宽时主要考虑了当前分得的带宽和聚集类的队列长度增量这两个因素.仿真实验结果说明了该方法的有效性.     

Increasing airport capacity utilisation through optimum slot scheduling: review of current developments and identification of future needs

Most of the busiest airports worldwide experience serious congestion and delay problems which call for some immediate capacity and demand management action. Solutions aiming to manage congestion through better slot scheduling have lately received a great deal of consideration due to their potential for delivering quick and substantial capacity utilisation improvements. A slot scheduling approach brings promises to cope better with congestion problems in the short to medium run and in a more sustainable way based on existing resources. This paper aims to provide a critical review of current research in declared capacity modelling and strategic slot scheduling. Furthermore, it goes beyond the critical review of current research developments by identifying future research issues and gaps and developing concrete directions towards modelling and solving advanced single airport and network-based slot scheduling problems. Our research findings suggest that the next generation of slot scheduling models should explore variations of currently used objectives (e.g., alternative expressions of schedule delay) and most importantly enrich them with fairness and equity, resource utilisation and environmental considerations. Future modelling efforts should also aim to further investigate airlines’ utility of alternative slot allocation outcomes, including various acceptability measures and levels of tolerance against schedule displacements. Last but not least, future research should intensively focus on the development and validation of computationally viable and robust slot scheduling models being able to capture the complexity, dynamic nature and weather-induced uncertainty of airport operations, along with hybrid solution approaches being able to deal with the size and complexity of slot allocation at network level.     

自适应带宽的最大-最小公平性拥塞控制

带宽共享和拥塞控制对于Internet的健壮性和公平性是很重要的研究课题.对交换设备中流量共享拥塞链路的带宽公平分配进行研究,提出一个优化交换设备带宽的设置算法:根据出端口接收速率自适应设置入端口带宽门限,对入端口的带宽进行动态重新分配,提高资源利用率.模拟实验表明,此算法有以下优点:1)高适应性;2)最大最小公平性;3)快速响应网络变化;4)高可靠性;5)稳定性.