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基于服务标识的网络交换调度机制是当前一个重要的研究课题.文中分析了中间级缓存多级多平面交换结构内部阻塞性、模拟最优OQ结构、链路加速比的技术特性,建立了基于均衡指针和动态时延指针的调度模型,设计了采用"请求-响应-确认"策略的均衡迭代和时延保证迭代调度算法.该算法克服了iSLIP和PPS方法在高负载强度下时延发散问题,在突发流量和非均匀diagonal流量下均可实现时延保证性能,在交换平面数p为4和迭代次数Iteration为4条件下可收敛至最优时延曲线. 相似文献
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调度算法一直是交换系统中不可或缺的研究内容.为满足新型高速路由及交换系统的研究需求,提出一种主动授权并发轮询调度算法——CRRD-AG算法.多级交换结构Clos交换网络以其良好的可扩展性作为高速交换结构倍受关注,但与之相适应的调度算法却并不多.目前主流算法,如并发分派算法(CD)和基于轮询的并发分派算法(CRRD),不是吞吐率较低就是所处理的业务流单一.CRRD-AG算法以CRRD为基础,将经典的"请求-授权-接受"的匹配计算模式改进为"主动授权-接受"的匹配模式,不仅能够降低CRRD算法在第1阶段的仲裁信息量,而且充分利用了中间级链路带宽,从而降低了整个系统的平均延迟,提高了吞吐率.进行充分的实验后,其结果表明,无论是在均匀业务,还是在突发业务环境中,CRRD-AG算法都能保证100%的吞吐率,更为重要的是,在不降低吞吐率的情况下能够显著改善分组的平均延迟. 相似文献
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一种支持DiffServ模型的全分布式调度算法 总被引:1,自引:0,他引:1
调度算法设计对于网络路由设备实现区分服务(DiffServ)模型的单跳行为(per hop behavior,简称PHB)至关重要.现有支持DiffServ模型的调度算法普遍基于输出排队(output queued,简称OQ)或是输入排队(input queued,简称IQ)交换结构进行设计,均无法在高速环境下提供高性能的调度.基于联合输入/交叉节点排队(combinedinput-crosspoint-queued,简称CICQ)交换结构提出一种支持DiffServ模型的全分布式调度算法DDSS (distributed DiffServ supporting scheduling),并通过理论分析对其公平性进行了验证.DDSS算法采用基于预约带宽的逐级流量控制机制实现所有预约带宽在快速转发(expedited forwarding,简称EF)业务与确保转发(assured forwarding,简称AF)业务之间的分配,采用优先级调度机制为EF业务提供低延迟服务,算法复杂度为O(log N).仿真结果表明,DDSS算法具有良好的时延性能和公平特性,与现有算法相比,能够更好地支持DiffServ模型. 相似文献
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拓扑结构和路由算法是影响多级交换网络性能的重要因素.在比较多种多级互连拓扑属性的基础上,提出将3D Torus结构应用于大规模交换网络设计.然后针对3D Torus交换网络中报文路由面临的两个关键问题:多路径负载均衡和报文保序,提出一种基于维序的多路径路由算法DMR(dimension-order—based multi—path routing).该算法可在保证报文顺序的同时在多条路径上平衡负载,提高交换网络吞吐率.最后通过模拟验证了算法的性能,并与维序路由和随机路由算法进行了比较.模拟结果表明,DMR算法的性能优于维序路由算法,能够达到随机路由算法性能水平,同时具有随机路由算法所不具备的报文保序特性. 相似文献
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一种具有信元保序能力的Clos网络分布式调度算法 总被引:1,自引:0,他引:1
分组交换三级Clos网络信元调度算法可分为集中式和分布式两种实现方式.分布式调度具有良好的可扩展性,适于在高速大容量环境中应用.然而由于分布式调度会带来同一分组各个信元间的乱序问题,给其实现带来困难.该文提出了一种具有信元保序能力的三级Clos网络分布式调度算法.该算法包括第一级的均匀负载分配、中间级的并行调度和第三级的按序输出调度三部分.文中对算法的性能进行了严格的理论证明和相关的仿真分析,表明该算法可以很好地解决传统分布式调度中的信元乱序问题,具有良好的性价比. 相似文献
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得益于无线能量传输技术的突破,体域网节点可以捕获射频能量源的无线电波能量进行充电,从而持续不间断地工作.对能量源数量和位置进行合理规划可以有效提高节点的能量捕获功率,降低部署成本.现有工作大多考虑节点静止情况下的能量源部署问题或通过概率统计模型转化为节点静止的情况,因此具有明显的局限性.考虑体域网应用背景下,携带可穿戴节点的用户具有特定停留-移动模式,基于该模型归纳了满足节点能量不中断概率要求的能量源优化布置问题,并将该问题的限制条件分解,转化为一个等价问题.分别基于贪婪算法和分治-粒子群算法设计了能量源优化布置算法.通过多组仿真实验,在不同参数下将两种算法与现有路径覆盖算法的性能进行了对比.实现结果表明,在满足节点能量不中断概率要求的前提下,分治-粒子群算法相比贪婪算法和路径覆盖算法更能节省能量源部署成本. 相似文献
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针对电压型PWM整流器开关频率附近的高次谐波污染电网,传统的电压型PWM整流器的控制策略都是基于两相旋转坐标系,存在电流交叉耦合项、计算量大的问题,提出了一种两相静止坐标系下基于LCL滤波器的PWM整流器的控制算法。该算法利用Clark变换系将三相静止坐标系下的电压型PWM整流器系统变换到两相静止坐标系下的电压型PWM整流器系统,避免了两相旋转坐标系下的电流交叉耦合项;采用准谐振调节器控制电压型PWM整流器的电流,实现了电流的跟踪控制。Matlab仿真结果验证了该算法的正确性和可行性。 相似文献
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This paper concerns an optimal control problem defined on a class of switched-mode hybrid dynamical systems. The system's
mode is changed (switched) whenever the state variable crosses a certain surface in the state space, henceforth called a switching
surface. These switching surfaces are parameterized by finite-dimensional vectors called the switching parameters. The optimal
control problem is to minimize a cost functional, defined on the state trajectory, as a function of the switching parameters.
The paper derives the gradient of the cost functional in a costate-based formula that reflects the special structure of hybrid
systems. It then uses the formula in a gradient-descent algorithm for solving an obstacle-avoidance problem in robotics.
The work of Boccadoro has been partially supported by MIUR under Grant PRIN 2003090090.
The work of Wardi has been partly supported by a grant from the Georgia Tech Manufacturing Research Center.
The work of Egerstedt has been partly supported by the National Science Foundation under Grant \# 0237971 ECS NSF-CAREER,
and by a grant from the Georgia Tech Manufacturing Research Center. 相似文献
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Mani M. Tousi Idin Karuei Shahin Hashtrudi-Zad Amir G. Aghdam 《Systems & Control Letters》2008,57(2):132-141
In this paper, the problem of designing a switching policy for an adaptive switching control system is formulated as a problem of supervisory control of a discrete-event system (DES). Two important problems in switching control are then addressed using the DES formulation and the theory of supervisory control under partial observation. First, it is verified whether for a given set of controllers, a switching policy satisfying a given set of constraints on the transitions among controllers exists. If so, then a minimally restrictive switching policy is designed. Next, an iterative algorithm is introduced for finding a minimal set of controllers for which a switching policy satisfying the switching constraints exists. It is shown that in the supervisory control problem considered in this paper, limitations on event observation are the factors that essentially restrict supervisory control. In other words, once observation limitations are respected, limitations on control will be automatically satisfied. This result is used to simplify the proposed iterative algorithm for finding minimal controller sets. 相似文献
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This paper studies an optimal control problem for uncertain switched linear systems with subsystems perturbed by uncertainty. A model for this problem is investigated with optimistic value criterion. The goal is to jointly design a deterministic switching law and a continuous feedback to optimize an uncertain objective function. A two-stage algorithm is applied to handle such model. In the first stage, the maximum value of the objective function and the bang–bang control are obtained under fixed switching instants, and in the second stage, GA and PSO algorithm are used to get the optimal switching instants, respectively. An example is shown to validate the method. 相似文献
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切换布尔网络是一种典型的网络化控制系统, 在基因调控、信息安全、人工智能、电路设计等领域具有重
要应用. 本文基于牵制控制方法, 研究切换布尔网络在任意切换下的分布式集合镇定问题. 首先, 利用矩阵半张量积
方法,得到切换布尔网络的代数形式. 其次, 基于代数形式, 提出构造性的算法来实现切换布尔网络在牵制控制的
作用下任意切换集合镇定, 并设计出状态反馈牵制控制器. 再次, 利用逻辑矩阵分解技术和分布式控制方法, 设计任
意切换下切换布尔网络的分布式集合镇定控制器, 并提出分布式控制器存在的充分条件. 文中给出3个例子来说明
所获得结果的有效性. 相似文献
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针对基于超文本传输协议(HTTP)的动态自适应流(DASH)码率自适应算法未能充分利用视频缓存以及平均码率偏低的问题,提出一种DASH标准的基于缓存补偿的码率自适应切换(BASBC)算法。首先,根据最近下载分片的下载速率分析带宽波动程度并得到预估带宽;其次,依据预估带宽和当前码率等级在缓存区设置码率上切阈值和码率下切阈值,并利用动态上切阈值控制码率向上切换,消耗缓存时长,而利用动态下切阈值控制码率向下逐级切换,累积缓存时长,从而在缓存区形成累积-消耗的缓存状态循环。BASBC算法在视频播放平均码率上高于动态自适应的HTTP流码率渐进切换(DASBS)算法,有效提高了带宽利用率;虽然所提算法的平均码率稍低于基于DASH标准的码率平滑切换(RSS)算法,但所提算法的码率切换更为平滑,整体切换稳定性表现更优。实验结果表明,所提算法在动态网络环境中具有高带宽利用、切换平滑且稳定的良好表现,能够有效提高用户的体验质量(QoE)。 相似文献
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A Condition for Boundedness of Solutions of Bidimensional Switched Affine Systems With Multiple Foci and Centers
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Liying Zhu 《Asian journal of control》2018,20(1):585-594
This paper studies boundedness of solutions of bidimensional switched affine linear systems. Every subsystem of the systems has a single stable/ unstable focus/ center and all the equilibria pairwise differ. By using the multiple polar coordinate systems method, this paper proposes a condition of boundedness of solutions of such switched systems under periodic/ quasi‐periodic switching paths. The condition is also shown a sufficient condition of global asymptotic region stability of such switched systems with respect to a region containing all multiple equilibria. A global asymptotic region‐stabilizing control, a periodic/ quasi‐periodic switching path, and a corresponding algorithm are all designed for such switched control systems. An illustrative example demonstrates the effectiveness and practicality of our new results. 相似文献