一种新的以太网流量控制算法研究

本文对用于千兆位以太网的流量控制算法做了介绍,对市场上应用比较成功的流量控制算法进行了分析,给出了一种新的流量控制算法.硬件实现和VCS仿真的结果证明本文提出的流量控制算法不仅硬件实现简单而且能有效地防止队头阻塞.     

基于多组博弈的新型网络流量控制模型

该文研究了具有强分布式特征和分层结构的通信网络流量控制问题,借鉴多组博弈模型来研究新型的网络流量控制模型,构造了基于网络流量速率和时延为参数的流量效用函数,使之能适度地满足不同业务的用户流量QoS需求,利用多组博弈优化模型建立了基于Min-Max的公平的网络流量控制博弈模型。理论上证明了提出的网络流量控制模型的非劣纳什策略存在性。数值仿真验证了模型的正确性,仿真结果验证了用户流量在非劣纳什均衡点的效用值是帕累托占优的。     

Theory of Flow Control in Shared Networks and Its Application in the Canadian Telephone Network

A shared network is largely oversubscribed by independent users who make random demands on the network. Network flow control is required for the orderly operation of the network under all potential traffic loads. This paper presents a qualitative analysis of the theory of flow control to circuit-switched and packet-switched networks and pro- ,. poses 4 complementary controls and 1 subtended control to constitute "flow control." They are traffic control, routing and delay control, congestion control, network management control, and end-end flow control. This paper introduces the concept of the "R-T function" to illustrate the synthesis of delays and routing freedoms, and to demonstrate the continuum between overload and congestion phenomena. The application of the qualitative theory of flow control to the Canadian Telephone Network is reviewed and the agreement between the theory and the practice is demonstrated. The telephone network is a prime example of a circuit-switched network which has received the benefit of extensive simulation and analytical studies, as well as a long experience to validate the conclusions reached in this paper.     

C＋＋反编译中控制流图优化方法研究

控制流分块是反编译系统中基本的功能之一。介绍了控制流分块方法,分析了C＋＋语言与C语言的区别。指出了现有的控制流分块方法用于C＋＋逆向的拿限性,提出了改进C＋＋逆向中流程分块的方法,给出了基于模块特征识别的算法,在部分开源架构中进行实验并取得了较好的效果。     

Reliable and efficient hop-by-hop flow control

Hop-by-hop flow control can be used to fairly share the bandwidth of a network among competing flows. No data is lost even in overload conditions; yet each flow gets access to the maximum throughput when the network is lightly loaded. However, some schemes for hop-by-hop flow control require too much memory; some of them are not resilient to errors. The authors propose a scheme for making hop-by-hop flow control resilient and show that it has advantages over the first several schemes proposed by Kung . They also describe a novel method for sharing the available buffers among the flows on a link; the scheme allows to potentially reduce the memory requirement (or increase the number of flows that can be supported) by an order of magnitude. Most of the work is described in the context of an ATM network that uses credit-based flow control. However, the ideas extend to networks in which flows can be distinguished, and to rate-based flow control schemes     

单片机流量控制系统在高频电刀中的应用

氩气高频电刀在医疗上有重要应用,氩气流量的调节与控制是其关键技术。文章介绍了氩气流量控制系统的原理、结构及相关的电路。在强电磁辐射干扰的环境下,该系统实现了对氩气流量的精密调节与控制,其控制精度为±０．２Ｌ／ｍｉｎ,具有实际应用价值。     

Interworking of switched ethernet and ATM flow control mechanisms

In this paper, we evaluate the performance of TCP in a network where the IEEE 802.3x flow control and the ATM Available Bit Rate flow control mechanisms are interworked. The objective is to examine whether an interworking of the two flow control mechanisms can improve the performance of upper‐layer protocols like TCP which is an end‐to‐end connection‐based transport protocol. The simulation studies show that the two interworked flow control mechanisms result in high link utilization while providing very low loss rates when used in conjunction with TCP. The flow control mechanisms complement each other. Copyright © 2002 John Wiley & Sons, Ltd.     

带压力保护的PID流量控制器

工业生产中的流量控制一般采用通用的PID控制器,这种方式的缺点是在控制流量的同时无法控制压力。为了能在控制流量的同时保证压力在允许的范围内,设计了一款带压力保护的流量控制器。该控制器同时采集流量和压力信号,当压力在允许范围内时,进行正常的流量控制。而当压力超标时,降低流量,从而降低压力,以保护设备。详细阐述了控制器的接口电路,并给出了PID算法和控制策略。     

一种智能蒸汽压力与流量测控器的研制

本文介绍了一种用于蒸汽压力和流量测量与控制的智能测控器。该测控器可同时测量蒸汽压力、蒸汽流量和蒸汽流量累计，同时可控蒸汽压力或蒸汽流量，并具备与上位计算机通讯功能。     

LTE系统中事件驱动M2M业务的流量控制随机接入协议

提出了一种LTE系统中事件驱动M2M业务的流量控制随机接入协议。采用贝塔分布对事件驱动M2M业务建模,通过统计一段时隙内的随机接入前导码空闲比来估计信道流量,从而设计控制因子进行流量控制。建模分析了采用该协议的系统吞吐量和时延性能,与目前在LTE系统中的随机接入协议的性能进行了对比。结果表明,该随机接入协议能够很好地估计系统负载,通过控制因子减少碰撞,从而显示出更好的系统性能。     

流特征感知的软件定义网络控制器动态关联机制

在部署分布式控制平面的软件定义网络中,控制器与交换机的关联仅以数据流请求的数量分布作为控制资源分配的依据。该文针对这一问题,以数据流的源目的地址特征为例,对不同特征数据流的控制资源消耗进行了分析,提出在控制资源分配中应对数据流的特征分布加以考虑。然后,设计了一种流特征感知的控制器关联决策机制,并针对网络流的动态变化特性设计了一种快速求解算法。仿真结果表明,与基于负载均衡的机制对比,所提机制在使用模拟退火算法求解时能节省10%～20%的控制资源消耗;所提快速求解算法可节省10%的资源消耗,且相比模拟退火算法具有较大的速度优势和良好的可扩展性。     

基于非合作博弈的无线自组织网络流量控制模型

该文根据无线自组织网络中流量控制和无线信道的特性,利用非合作博弈理论构造了基于网络流量速率和时延为参数的流量效用函数,建立了非合作博弈的无线自组织网络流量控制模型,证明了流量控制模型的Nash均衡解存在性,给出了模型的Nash均衡解的具体形式。数值仿真结果表明该模型存在Nash均衡解,能有效对网络中流量进行控制,满足不同业务的用户流量QoS需求。     

冷水机组的联动控制策略

分析了在冷冻水系统运行中,可能导致出现低温差的原因,通过对回水温度控制,冷量测量方式控制,冷冻机负载,二次侧流量这几种联动控制策略比较和分析,得出利用二次侧流量的控制方式是几种方式中最佳的控制方式。有利于在满足末端负荷的前提下,冷冻机系统的稳定运行并且能够达到最佳的能效比。     

用于液压电梯调速的电液流量控制系统

根据比例流星阀输出流量与电梯桥厢速度之间的近似正比关系，应用带电反馈信号的比例流量阀构成流量闭环控制系统，间接实现对波压载客电梯升降速度的控制。该系统具有较好的抗干扰能力，对于轿厢负荷的变化或油湿的变化均有良好的适应性．     

Flow control in high-speed communication networks

Flow control within a virtual circuit on a high-speed network is modeled using fluid-flow queues with a fixed propagation delay for each channel. Data from other virtual circuits are modeled as disturbances of the available service capacities. The resulting dynamics are shown to form a linear hybrid system. This model allows the design of flow control mechanisms on a mathematical basis. Simulation results show a marked improvement over window flow control for a single channel, and a marginal improvement over window flow control for a virtual circuit of three tandem channels     

Congestion and flow control in Signaling System No. 7-impacts ofintelligent networks and new services

Focuses on the transient performance analysis of the congestion and flow control mechanisms in CCITT Signaling System No. 7 (SS7). Special attention is directed to the impacts of the introduction of intelligent services and new applications, e.g., Freephone, credit card services, user-to-user signaling, etc. In particular, the authors show that signaling traffic characteristics like signaling scenarios or signaling message length as well as end-to-end signaling capabilities have a significant influence on the congestion and flow control and, therefore, on the real-time signaling performance. One important result of the performance studies is that if, e.g., intelligent services are introduced, the SS7 congestion and flow control does not work correctly. To solve this problem, some reinvestigations into these mechanisms would be necessary. Therefore, some approaches, e.g., modification of the signaling connection control part (SCCP) congestion control, usage of the SCCP relay function, or a redesign of the message transfer part (MTP) flow control procedures are discussed in order to guarantee the efficacy of the congestion and flow control mechanisms also in the future     

Interactions Between Routing and Flow Control Algorithms

In this paper we discuss the interactions between routing and flow control algorithms for packet-switched networks. We present a new variation on the Gallager-Golestaani flow control scheme [4] and also a new variable window scheme. The tradeoff between throughput and network congestion is examined. It is shown that these two flow control schemes have the unique feature that the parameters can be specified to place an upper bound on the expected amount of network congestion.     

Scalable Network Architecture for Flow‐Based Traffic Control

Many control schemes have been proposed for flow‐level traffic control. However, flow‐level traffic control is implemented only in limited areas such as traffic monitoring and traffic control at edge nodes. No clear solution for end‐to‐end architecture has been proposed. Scalability and the lack of a business model are major problems for deploying end‐to‐end flow‐level control architecture. This paper introduces an end‐to‐end transport architecture and a scalable control mechanism to support the various flow‐level QoS requests from applications.     

Reliability of systems with two failure modes by using structure functions

This paper deals a three-state (normal, short-mode and open-mode failures) device network that is required to control the quantity of s-t flow. If the control policy is to pass the flow or to shut off the flow, i.e. the amount of s-t flow equals one, this network system is a conventional three-state system. In order to obtain the reliability of the network system, we propose a new structure function. Some examples are presented to show that using the structure function simplifies the reliability calculation.     

Flow Control in Packet-Switched Networks by Gradual Restrictions of Virtual Calls

A network flow control method in virtual circuit-oriented packet-switched networks, such as international packet-switched networks based on the CCITT X.75 protocol, is proposed. Lengths of individual queues to outgoing routes are observed constantly in a switch (or node), and the virtual calls connected to a congested outgoing route are restricted gradually depending upon the queue length. Being proportional to the number of virtual calls restricted simultaneously, the amount of processing load to carry out flow control can be decreased by the introduction of gradual restrictions. Priorities of calls can also be considered in flow control. The proposed flow control method is analyzed theoretically by a simple queueing model and basic traffic characteristies are shown. Optimum restriction factors and threshold values are obtained. Through several numerical examples, the effectiveness of the method is demonstrated. The amount of processing load is also analyzed and evaluated quantitatively.