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Another Fast and Simple DEM Depression-Filling Algorithm Based on Priority Queue Structure 被引量:4
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作者 LIU Yong-He ZHANG Wan-Chang XU Jing-Wen 《Atmospheric and Oceanic Science Letters》 2009年第4期214-219,共6页
Some depression cells with heights lower than their surrounding cells may often be found in Grid-based digital elevation models (DEM) dataset due to sampling errors.The depression-filling algorithm presented by Planch... Some depression cells with heights lower than their surrounding cells may often be found in Grid-based digital elevation models (DEM) dataset due to sampling errors.The depression-filling algorithm presented by Planchon and Darboux works very quickly compared to other published methods.Despite its simplicity and deli-cacy,this algorithm remains difficult to understand due to its three complex subroutines and its recursive execution.Another fast algorithm is presented in this article.The main idea of this new algorithm is as follows:first,the DEM dataset is viewed as an island and the outer space as an ocean;when the ocean level increases,the DEM cells on the island's boundary will be inundated;when a cell is inundated for the first time,its elevation is increased to the ocean level at that moment;after the ocean has inun-dated the entire DEM,all of the depressions are filled.The depression-removing processing is performed using a priority queue.Theoretically,this new algorithm is a fast algorithm despite the fact that it runs more slowly than Planchon and Darboux's method.Its time-complexity in both the worst case and in an average case is O(8nlog 2 (m)),which is close to O(n).The running speed of this algorithm depends mainly on the insertion operation of the priority queue.As shown by the tests,the depres-sion-filling effects of this algorithm are correct and valid,and the overall time consumption of this algorithm is less than twice the time consumed by Planchon & Darboux's method for handling a DEM smaller than 2500×2500 cells.More importantly,this new algorithm is simpler and easier to understand than Planchon and Darboux's method This advantage allows the correct program code to be written quickly. 展开更多
关键词 digital elevation models depression removing priority queue quick algorithm
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The Effect of Queuing Mechanisms First in First out (FIFO), Priority Queuing (PQ) and Weighted Fair Queuing (WFQ) on Network’s Routers and Applications 被引量:4
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作者 Mustafa El Gili Mustafa Samani A. Talab 《Wireless Sensor Network》 2016年第5期77-84,共8页
The paper presents the simulation results of the comparison of three Queuing Mechanisms, First in First out (FIFO), Priority Queuing (PQ), and Weighted Fair Queuing (WFQ). Depending on their effects on the network’s ... The paper presents the simulation results of the comparison of three Queuing Mechanisms, First in First out (FIFO), Priority Queuing (PQ), and Weighted Fair Queuing (WFQ). Depending on their effects on the network’s Routers, the load of any algorithm of them over Router’s CPUs and memory usage, the delay occurred between routers when any algorithm has been used and the network application throughput. This comparison explains that, PQ doesn’t need high specification hardware (memory and CPU) but when used it is not fair, because it serves one application and ignore the other application and FIFO mechanism has smaller queuing delay, otherwise PQ has bigger delay. 展开更多
关键词 Queuing Mechanisms QoS First in First out (FIFO) priority Queuing (pq) Weighted Fair Queuing (WFQ)
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Diffusion approximations for multiclass queueing networks under preemptive priority service discipline
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作者 戴万阳 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第10期1331-1342,共12页
We prove a heavy traffic limit theorem to justify diffusion approximations for multiclass queueing networks under preemptive priority service discipline and provide effective stochastic dynamical models for the system... We prove a heavy traffic limit theorem to justify diffusion approximations for multiclass queueing networks under preemptive priority service discipline and provide effective stochastic dynamical models for the systems. Such queueing networks appear typically in high-speed integrated services packet networks about telecommunication system. In the network, there is a number of packet traffic types. Each type needs a number of job classes (stages) of processing and each type of jobs is assigned the same priority rank at every station where it possibly receives service. Moreover, there is no inter-routing among different traffic types throughout the entire network. 展开更多
关键词 queueing network preemptive priority heavy traffic semimartingale re-flecting Brownian motion fluid model diffusion approximation Lyapunov function
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VIRTUAL WAITING TIMES IN PRIORITY-M/G/1 QUEUES WITH VACARIONS
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作者 CONG,TANG DAC (Department of Mathematics, University of Amsterdam, Plantage Muidergracht 24, 1018 TV Amsterdam, The Netherlands). 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 1995年第3期297-312,共16页
In this paper exhaustive-service priority-M/G/1 queueing systems with multiple vacations, single vacation and setup times are studied under the nonpreemptive and preemptive resume priority disciplines. For each of the... In this paper exhaustive-service priority-M/G/1 queueing systems with multiple vacations, single vacation and setup times are studied under the nonpreemptive and preemptive resume priority disciplines. For each of the six models analysed, the Laplace-Stieltjes transform of the virtual waiting time Wk(t) at time t of class k is derived by the method of collective marks. A sufficient condition for , where U has the standard normal distribution, is also given. 展开更多
关键词 priority queues vacations virtual waiting times collective marks
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A Non-Preemptive Priority Queueing System with a Single Server Serving Two Queues M/G/1 and M/D/1 with Optional Server Vacations Based on Exhaustive Service of the Priority Units
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作者 Kailash C. Madan 《Applied Mathematics》 2011年第6期791-799,共9页
We study a vacation queueing system with a single server simultaneously dealing with an M/G/1 and an M/D/1 queue. Two classes of units, priority and non-priority, arrive at the system in two independent Poisson stream... We study a vacation queueing system with a single server simultaneously dealing with an M/G/1 and an M/D/1 queue. Two classes of units, priority and non-priority, arrive at the system in two independent Poisson streams. Under a non-preemptive priority rule, the server provides a general service to the priority units and a deterministic service to the non-priority units. We further assume that the server may take a vacation of random length just after serving the last priority unit present in the system. We obtain steady state queue size distribution at a random epoch. Corresponding results for some special cases, including the known results of the M/G/1 and the M/D/1 queues, have been derived. 展开更多
关键词 Non PREEMPTIVE priority queueING SYSTEM Modified Server Vacations Combination of General SERVICE and Deterministic SERVICE Steady State queue Size Distribution
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Modeling and Performance Analysis of Weighted Priority Queueing for Packet-Switched Networks
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作者 Dariusz Strzeciwilk Wlodek M. Zuberek 《Journal of Computer and Communications》 2018年第11期195-208,共14页
Weighted priority queueing is a modification of priority queueing that eliminates the possibility of blocking lower priority traffic. The weights assigned to priority classes determine the fractions of the bandwith th... Weighted priority queueing is a modification of priority queueing that eliminates the possibility of blocking lower priority traffic. The weights assigned to priority classes determine the fractions of the bandwith that are guaranteed for individual traffic classes, similarly as in weighted fair queueing. The paper describes a timed Petri net model of weighted priority queueing and uses discrete-event simulation of this model to obtain performance characteristics of simple queueing systems. The model is also used to analyze the effects of finite queue capacity on the performance of queueing systems. 展开更多
关键词 TIMED PETRI Nets Discrete-Event Simulation priority queueING WEIGHTED priority queueING Performance ANALYSIS
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A DYNAMIC CROSS-LAYER DATA QUEUE MANAGEMENT APPROACH BASED ON PRIORITY FOR DELAY-TOLERANT MOBILE SENSOR NETWORKS
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作者 Li Qiyue Li Jie +1 位作者 Wang Jianping Sun Wei 《Journal of Electronics(China)》 2013年第4期328-334,共7页
This paper presents a Dynamic Cross-layer Data Queue Management approach (DC-DQM) based on priority to address the priority deviation problem in Delay-Tolerant Mobile Sensor Networks (DT-MSNs). Receiver-driven data de... This paper presents a Dynamic Cross-layer Data Queue Management approach (DC-DQM) based on priority to address the priority deviation problem in Delay-Tolerant Mobile Sensor Networks (DT-MSNs). Receiver-driven data delivery scheme is used for fast response to data transfers, and a priority based interaction model is adopted to identify the data priority. Three interactive parameters are introduced to prioritize and dynamically manage data queue. The experimental results show that it can ameliorate data delivery ratio and achieve good performance in terms of average delay. 展开更多
关键词 Data queue Management (DQM) priority Delay-Tolerant Mobile Sensor Networks(DT-MSNs) INTERACTION
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连续时间完全-限定(K=2)两级轮询系统性能分析
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作者 杨志军 黄文洁 丁洪伟 《计算机工程》 CSCD 北大核心 2024年第1期191-197,共7页
为了实现区分网络优先级、保证公平性、提高普通站点的性能和效率,在完全-限定(K=1)两级轮询控制系统模型的基础上,提出连续时间完全-限定(K=2)两级轮询控制系统模型。在该模型中,使用限定(K=2)服务和完全服务分别对普通站点和中心站点... 为了实现区分网络优先级、保证公平性、提高普通站点的性能和效率,在完全-限定(K=1)两级轮询控制系统模型的基础上,提出连续时间完全-限定(K=2)两级轮询控制系统模型。在该模型中,使用限定(K=2)服务和完全服务分别对普通站点和中心站点进行服务。中心站点转换到普通站点进行服务时,使用捎带查询方式。在此基础上,采用马尔可夫链和概率母函数的数学方法建立该轮询系统模型,并推导平均排队队长和时延。利用MATLAB进行仿真实验,结果表明:理论值与仿真值误差较小,验证了理论分析的正确性;与门限-完全服务模型相比,该模型中心站点的队长和时延均小于门限-完全服务中心站点的队长和时延,具有更高的优先级;与一级完全服务和一级限定(K=2)服务模型相比,区分了优先级,性能分别提升11.7%和14.5%,说明两级服务远好于一级服务;与完全-限定(K=1)两级服务模型相比,增加了发送的数据,减少了等待时间,性能提升13.04%左右,进一步优化了普通站点的性能。 展开更多
关键词 优先级 连续时间 完全-限定(K=2) 平均排队队长 平均时延 服务效率
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基于MEC服务器优先服务的路侧单元MAC层调度策略
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作者 李欣 保利勇 +1 位作者 丁洪伟 官铮 《计算机应用》 CSCD 北大核心 2024年第4期1227-1235,共9页
针对多接入边缘计算(MEC)服务器高可靠、低时延和大数据量的数据传输要求,基于无冲突接入、优先级架构和弹性服务技术,提出一种适用于车辆边缘计算场景下的媒体访问控制(MAC)调度策略。所提策略由车联网(IoV)路侧单元(RSU)集中协调信道... 针对多接入边缘计算(MEC)服务器高可靠、低时延和大数据量的数据传输要求,基于无冲突接入、优先级架构和弹性服务技术,提出一种适用于车辆边缘计算场景下的媒体访问控制(MAC)调度策略。所提策略由车联网(IoV)路侧单元(RSU)集中协调信道接入权,优先确保车载网络中车载通信单元(OBU)与MEC服务器之间的链路传输质量,以及时传输车辆到网络(V2N)业务数据;同时,对本地OBU之间的业务采取弹性服务方式,增强密集车辆接入时应急消息传输的可靠性。首先,构建调度策略的排队分析模型;其次,根据各时刻系统状态变量的无后效性特点建立嵌入式马尔可夫链,并通过概率母函数的分析方法对系统进行理论分析,得到MEC服务器通信单元和OBU的平均排队队长、平均等待时延和RSU查询周期等关键指标的精确解析表达式。计算机仿真实验结果表明,统计分析结果与理论计算结果一致,所提调度策略在高负载情况下能够提高IoV的稳定性和灵活性。 展开更多
关键词 车联网 媒体访问控制层调度 优先级架构 平均排队队长 平均等待时延
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基于最小权覆盖的医药电商配送中心选址及区域覆盖优化研究
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作者 李建红 丁秀好 +1 位作者 雷鸣颢 罗晓萌 《运筹与管理》 CSCD 北大核心 2024年第4期7-13,共7页
配送中心选址及区域划分是物流配送过程中的关键环节,直接决定了配送时效及配送成本,在当今电子商务领域显得尤为重要。本文针对国内医药电商企业,提出了一种考虑药品配送时效的配送中心选址策略;随后建立该问题的整数规划模型,采用最... 配送中心选址及区域划分是物流配送过程中的关键环节,直接决定了配送时效及配送成本,在当今电子商务领域显得尤为重要。本文针对国内医药电商企业,提出了一种考虑药品配送时效的配送中心选址策略;随后建立该问题的整数规划模型,采用最小权顶点覆盖方法描述问题,并通过优先队列分支限界算法对此模型进行求解,得出最优选址结果;最后按最小运费原则将被重复覆盖区域进行再划分,得到配送中心选址及区域划分最终方案。本文基于上述策略为国内某头部医药电商企业提供了两种选址方案:保留企业原有配送中心并确定新配送中心选址点(改进选址方案)和从企业所有需求节点中重新为配送中心选址(重选址方案),并使用企业真实销量和物流数据进行算例分析。 展开更多
关键词 配送中心选址 区域划分 最小权顶点覆盖 优先队列分支限界算法
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DPQS:MANET中一种有效的队列调度机制
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作者 霍英 陈志刚 《计算机工程与应用》 CSCD 北大核心 2006年第14期22-25,共4页
提出一种针对移动自组网的动态优先权队列调度机制(DynamicPriorityQueueScheduling,DPQS)。为缓冲区设置最大、最小两个阈值,将其分为三个不同的负载阶段,然后根据当前缓冲区的负载情况动态调整各种类型数据包的优先等级,从而在不影响... 提出一种针对移动自组网的动态优先权队列调度机制(DynamicPriorityQueueScheduling,DPQS)。为缓冲区设置最大、最小两个阈值,将其分为三个不同的负载阶段,然后根据当前缓冲区的负载情况动态调整各种类型数据包的优先等级,从而在不影响快速建立路由的前提下,降低数据包在网络中的传输延时,提高网络的性能。仿真结果表明DPQS机制有效地降低了网络传输延时,并对网络的吞吐量也有一定的提高。 展开更多
关键词 移动自组网 队列调度 优先权
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C-V2X网联环境下应急优先的绿灯补偿模型研究
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作者 张长隆 韩发荣 +3 位作者 魏吉敏 戴金钢 杨晓东 瞿仕波 《电信科学》 北大核心 2024年第1期59-70,共12页
针对在路口实施应急车辆优先策略会对非优先相位交通造成影响的问题,在蜂窝车联网(C-V2X)环境下进行了均衡非优先相位通行效益的绿灯补偿模型研究。搭建了相应的算法模型,并对一辆应急车辆的场景进行了模拟。该模型在不影响应急车辆优... 针对在路口实施应急车辆优先策略会对非优先相位交通造成影响的问题,在蜂窝车联网(C-V2X)环境下进行了均衡非优先相位通行效益的绿灯补偿模型研究。搭建了相应的算法模型,并对一辆应急车辆的场景进行了模拟。该模型在不影响应急车辆优先通行的前提下,根据非优先相位实时交通需求计算补偿绿灯时间,从而最小化应急优先对非优先相位的车辆通行影响。仿真结果证明,所提模型在不同的饱和度状态下均可有效地降低应急车辆通过后非优先相位车辆的平均延误时间和平均排队长度。所提模型对于应急车辆通过红绿灯路口的策略进行了优化,提高了通行效率。 展开更多
关键词 应急车辆优先 C-V2X 非优先相位 绿灯补偿 排队长度
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基于改进A^(*)算法的路径规划研究
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作者 蔡梓丰 张延生 +1 位作者 梁先樟 罗世豪 《现代信息科技》 2024年第10期51-55,59,共6页
研究了A^(*)算法在二、三维模型路径规划中的优化方法。通过实时阈值法和惩罚因子法减少开放列表中不必要的搜索空间和冗余路径;采用自定义优先级队列、二叉堆法和哈希表替代传统A^(*)算法中的处理方式;在对二维地图的研究中,采用局部A^... 研究了A^(*)算法在二、三维模型路径规划中的优化方法。通过实时阈值法和惩罚因子法减少开放列表中不必要的搜索空间和冗余路径;采用自定义优先级队列、二叉堆法和哈希表替代传统A^(*)算法中的处理方式;在对二维地图的研究中,采用局部A^(*)算法避免大面积搜索。实验结果表明,经过改进的A^(*)算法显著提高了搜索和路径规划速度,减少了计算时间和内存消耗,验证了该算法的可行性和有效性。 展开更多
关键词 路径规划 三维规划 惩罚因子 二叉堆与自定义优先级队列 实时阈值 局部A^(*)算法
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An efficient priority service model with two-level-polling scheme 被引量:4
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作者 Liu Qianlin Zhao Dongfeng Zhao Yifan 《High Technology Letters》 EI CAS 2011年第3期245-251,共7页
This paper considers an efficient priority service model with two-level-polling scheme which the message packets conform to the discrete-time Geom/G/1 queue with multiple vacations and bulk arrival. By the embedded Ma... This paper considers an efficient priority service model with two-level-polling scheme which the message packets conform to the discrete-time Geom/G/1 queue with multiple vacations and bulk arrival. By the embedded Markov chain theory and the probability generating function method, we set up the mathematics functions and give closed form expressions for obtaining the mean cyclic period (MCP), the mean queue length (MQL) and the mean waiting time (MWT) characteristics, the analytical results are also verified through extensive computer simulations. The performance analysis reveals that this priority polling scheme can gives better efficiency as well as impartiality in terms of system characteristics, and it can be used for differentiating priority service to guarantee better QoS and system stability in design and improvement of MAC protocol. 展开更多
关键词 priority service Geom/G/1 queue mean queue length(MQL) mean waiting time (MWT)
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Dynamic Handoff Priority Adjustment Based on Mobility-Awareness in Multimedia Cellular Networks
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作者 Chow-Sing Lin Pin-Jing Huang 《International Journal of Communications, Network and System Sciences》 2011年第8期495-506,共12页
In multimedia cellular networks, when a Mobile Host requests multimedia services, it may experience hand-offs to several cells before the request is completely served. If a target cell cannot provide adequate bandwidt... In multimedia cellular networks, when a Mobile Host requests multimedia services, it may experience hand-offs to several cells before the request is completely served. If a target cell cannot provide adequate bandwidth for a service request, instead of directly dropping the request, the MH is put into the handoff queue and hopefully the requested bandwidth can be satisfied by later released bandwidth. Obviously, it is important to properly assign priorities for queued handoff of MHs based on their inborn dynamics to avoid unnecessary dropping. In this paper, we present a dynamic handoff priority adjustment scheme which applied a handoff queuing scheme to dynamically adjust handoff priority based on receiving signal strength, service class, and mobility of Mobile Hosts. In addition, idle bandwidth reserved by inactive MHs is reallocated to urgent handoff MHs to reduce the call dropping probability. The goal of the proposed dynamic handoff priority adjustment scheme is to further reduce call dropping probability while still maintaining high bandwidth utilization and acceptable call blocking probability on multimedia cellular networks. 展开更多
关键词 MULTIMEDIA Cellular Network HANDOFF priority HANDOFF queue Quality of Service MOBILITY
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Real Time Systems with Nonpreemptive Priorities and Ample Maintenance Facilities
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作者 Joseph Kreimer Edward Ianovsky 《Journal of Computer and Communications》 2015年第7期32-45,共14页
We consider a real time data acquisition and processing multiserver system with identical servers (such as unmanned aerial vehicles, machine controllers, overhearing devices, medical monitoring devices, etc.) which ca... We consider a real time data acquisition and processing multiserver system with identical servers (such as unmanned aerial vehicles, machine controllers, overhearing devices, medical monitoring devices, etc.) which can be maintained/programmed for different kinds of activities (e.g. passive or active). This system provides a service for real time tasks arriving via several channels (such as surveillance regions, assembly lines, communication channels, etc.) and involves maintenance. We focus on the worst case analysis of the system with ample maintenance facilities exponentially distributed time to failure and maintenance times. We consider two kinds of models (with and without nonpreemptive priorities) and provide balance equations for steady state probabilities and various performance measures, when both operation and maintenance times are exponentially distributed. 展开更多
关键词 Performance priority queueING REAL TIME System Unmanned AERIAL VEHICLES
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A Priority Queuing Model for HCF Controlled Channel Access (HCCA) in Wireless LANs
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作者 Reza GHAZIZADEH Pingzhi FAN Yi PAN 《International Journal of Communications, Network and System Sciences》 2009年第1期30-43,共14页
Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11... Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11 standard series to enhance access medium supporting QoS for multimedia applications. However, some applications such as variable bit rate (VBR) traffic address some challenges in the hybrid coordination function (HCF) nominated to provide QoS. This paper presents a novel priority queuing model to analyze a medium access in the HCF controlled channel access (HCCA) mode. This model makes use of a MAP (Markovian Arrival Process)/PH (Phase Type)/1 queue with two types of jobs which are suitable to support VBR traffic. Using a MAP for traffic arrival process and PH distribution for service process, the inclusion of vacation period makes our analysis very general and comprehensive to support various types of practical traffic streams. The proposed priority queuing model is very useful to evaluate and enhance the performance of the scheduler and the admission controller in the HCCA mechanism. 展开更多
关键词 QoS HCCA priority queueS Matrix-Geometric Method MAP/PH/1
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Performance Analysis of Two Priority Queuing Systems in Tandem
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作者 Faouzi Kamoun 《American Journal of Operations Research》 2012年第4期509-518,共10页
In this paper, we consider a tandem of two head-of-line (HOL) non-preemptive priority queuing systems, each with a single server and a deterministic service-time. Two classes of traffic are considered, namely high pri... In this paper, we consider a tandem of two head-of-line (HOL) non-preemptive priority queuing systems, each with a single server and a deterministic service-time. Two classes of traffic are considered, namely high priority and low priority traffic. By means of a generating function approach, we present a technique to derive closed-form expressions for the mean buffer occupancy at each node and mean delay. Finally, we illustrate our solution technique with some numerical examples, whereby we illustrate the starvation impact of the HOL priority scheduling discipline on the performance of the low-priority traffic stream. Our research highlights the important fact that the unfairness of the HOL priority scheduling becomes even more noticeable at the network level. Thus this priority mechanism should be used with caution. 展开更多
关键词 priority QUEUING System TANDEM queueS Performance Analysis DISCRETE-TIME queueS
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A Load-based Queue Scheduling Algorithm for MANET
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作者 Zhigang Chen Zhihui Ge Ming Zhao 《通讯和计算机(中英文版)》 2006年第8期11-15,40,共6页
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信号预控下动态公交专用道策略 被引量:2
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作者 彭凤 韩直 徐冲聪 《科学技术与工程》 北大核心 2023年第3期1285-1291,共7页
针对高峰时期公交专用道利用率较低的问题,提出一种基于信号预控的动态公交专用道策略,提升道路资源时空利用。在保证公交优先基础上对交通流构成比例进行影响分析,确定了APL、IBL和DBL三种常用车道控制模式适用范围;以路段人均时耗最... 针对高峰时期公交专用道利用率较低的问题,提出一种基于信号预控的动态公交专用道策略,提升道路资源时空利用。在保证公交优先基础上对交通流构成比例进行影响分析,确定了APL、IBL和DBL三种常用车道控制模式适用范围;以路段人均时耗最小为目标函数,建立动态公交专用道规划模型,确定了各车道模式临界流量值;考虑交叉口信号差异下车道排队消散时长不同,构建基于信号预控下路段清空条件,实现公交专用道提前预控,建立了信号预控下动态公交专用道控制流程。以重庆市某段路为案例,选取全时段普通混合车道(all purpose lane,APL)、间歇式公交专用道(intermittent bus lane,IBL)和完全式公交专用道(dedicated bus lane,DBL)为参照,分别对实验路段和公交专用道进行评价分析。结果表明:本文动态公交专用道策略能够提高公交专用车道资源利用率,有效缓解公交优先和路段整体交通效率之间的矛盾。 展开更多
关键词 城市交通 动态公交专用道策略 信号预控 公交优先 排队清空
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