Payne-Whitham型宏观交通流模型波动特性

宏观交通流模型将交通流比拟成流体流,通过整体变量如交通流量、平均车速以及交通密度来研究其整体性质,得到了越来越多的肯定.文章采用波前展开的方法,研究Payne-Whitham型宏观交通流模型描述扰动沿交通流波动的特性,同时给出了相应的稳定性条件.最后利用Padé逼近法进行数值仿真,得到的结果与理论分析相一致.     

控制能量受限下一类离散无限维线性系统的精确零能控性

本文讨论控制能量受限下一类离散无限维线性系统的精确零能控性问题,作者利用Hilbert 空间中的固有值与固有元展开的方法,得到了这个问题所要满足的充要条件.设有如下的离散无限维线性系统     

低维宏观交通流模型的稳定性和分岔分析

交通流模型的分岔点对应临界的交通状态,对研究交通流的稳定性具有重要的理论意义.为了分析宏观交通流模型的分岔特征,通过对低维宏观交通流模型的求解得到两个平衡点,并讨论了其稳定性,发现该模型存在一个跨临界分岔点.数值仿真验证了结论的正确性,并且在一定条件下,通过改变响应时间会影响到最终的平衡状态.     

基于无振荡中心格式求解非均匀道路上的多车种LWR交通流模型

将无振荡中心格式推广于多车种LWR交通流模型,给出了一种求解非均匀道路上模型的高分辨率数值方法.为保证格式无振荡,采用非线性限制器近似离散斜率.通量的离散微分可以按分量来近似,使得雅可比矩阵的计算都可以避免.方法具有形式简单、计算量小的优点.应用该方法对信号灯控制等问题进行数值模拟,验证了方法的稳定性和有效性.     

一类单时滞线性系统的模糊变结构控制

研究了一类单时滞线性系统变结构控制律的设计方法,基于模糊T-S模型把一类单时滞线性系统化为若干个时滞子系统,然后对时滞子系统设计变结构控制律,取全局控制作为系统的控制律,从而达到对单时滞线性系统系统进行控制的目的,给出了单时滞系统的滑模稳定的条件.仿真表明控制策略的有效性.     

离散时间下广义多智能体系统基于观测器的分布式一致协议

研究了离散时间广义多智能体系统的容许性一致问题,并设计了基于观测器的分布式控制协议.假设每个智能体的动力学模型为离散时间的广义线性系统,智能体间的通讯拓扑结构为固定的有向图.在假设智能体的状态信息不能被直接利用的情况下,设计了基于观测器的一致协议,观测器的动力学模型是建立在正常线性系统之上,而不是广义系统.根据改进后的广义Riccati方程以及李亚普诺夫容许性定理,得到了容许一致的充分性条件.在文章所提供的设计方案下,基于全维或降维观测器的一致性协议可以通过解一些特殊条件获得,因此文章所提供的设计协议具有更强的包容性.最后提供了数值模拟仿真,验证了文章结论的正确性.     

基于数据驱动方法的控制器设计及其参数整定

以一般离散时间非线性系统为研究对象,提出一类基于数据驱动的控制器设计及其参数整定方法.方法首先依据非参数时变动态线性化定理提出3种控制器结构,再采用迭代反馈整定方法(IFT)优化其控制器参数,从根本上解决了IFT方法给定控制器结构时存在的盲目性.最后将该方法与另外两种数据驱动控制方法---无模型自适应控制(MFAC)和IFT方法进行比较研究,结果表明方法是有效的.     

跳跃扩散下双障碍期权定价的数值解

提出了一种求解带有跳跃的双障碍期权定价模型的数值方法.算法采用了Crank-Nicolson 有限差分格式和复化梯形公式对模型进行离散,对离散后的线性系统采用GMRES迭代法求解,并且构造了一个新的预处理算子以加速迭代法的收敛.数值实验验证了该方法能快速求解模型并达到二阶收敛精度.     

具有移动底边界的水波问题的仿线性化（英文）

主要研究了带表面张力的无旋不可压缩重力水波问题,该水波的流动区域除了有自由上边界外,还具有给定的移动底边界.主要目的是利用仿微分方法对非线性水波问题的Zakharov表示进行仿线性化,关键在于处理Dirichlet-Neumann算子.借助Possion核定义正则映射来拉平边界会使仿线性化过程更加精细.这一仿线性化结果使非线性的水波方程成为线性系统,为研究具有移动底边界的水波方程适定性奠定了基础.     

二维非稳态对流扩散边界控制问题的简化算法

针对二维非稳态对流扩散边界控制问题计算量大的问题,提出了基于降阶模型的最优实时控制方法.利用POD(the Proper Orthogonal Decomposition)和奇异值分解以及Galerkin投影方法得到了具有高精度离散形式的状态空间降阶模型.在所得的降阶状态空间模型中,利用离散时间线性二次调节器方法设计出了最优控制器.对流-扩散过程的控制模拟结果说明了所提方法的有效性和准确性.     

Output feedback guaranteed cost control of uncertain linear discrete systems with interval time-varying delays

This paper deals with output feedback guaranteed cost control problem for a general class of uncertain linear discrete delay systems, where the state and the observation output are subjected to interval time-varying delay. The proposed output feedback controller uses the observation measurement to exponentially stabilize the closed-loop system and guarantee an adequate level of system performance. By constructing a set of augmented Lyapunov–Krasovskii functionals, a delay-dependent condition for the robust output feedback guaranteed cost control is established in terms of linear matrix inequalities (LMIs). Three numerical examples are provided to demonstrate the efficiency of the proposed method.     

基于虚拟完整约束的欠驱动起重机控制方法

欠驱动系统的控制是非线性控制的一个重要领域,欠驱动系统指系统控制输入个数小于自由度个数的非线性系统.目前,欠驱动非线性系统动力学和控制研究的主要方法包括线性二次型最优控制方法和部分反馈线性化方法等,如何使系统持续的稳定在平衡位置一直是研究的难点.虚拟约束方法是指通过选择一个周期循环变化的变量作为自变量来设计系统的周期运动.该文以典型的欠驱动模型起重机为例,采用虚拟约束方法,使系统能够在平衡位置稳定或周期振荡运动.首先,通过建立虚拟约束,减少系统自由度变量;然后,通过部分反馈线性化理论推导出系统的状态方程;最后,通过线性二次调节器设计反馈控制器.仿真结果表明,重物在反馈控制下可以在竖直位置的附近达到稳定状态,反映了虚拟约束方法对欠驱动系统的有效性.     

Stabilization of delayed Cohen‐Grossberg BAM neural networks

This paper deals with finite‐time stabilization results of delayed Cohen‐Grossberg BAM neural networks under suitable control schemes. We propose a state‐feedback controller together with an adaptive‐feedback controller to stabilize the system of delayed Cohen‐Grossberg BAM neural networks. Stabilization conditions are derived by using Lyapunov function and some algebraic conditions. We also estimate the upper bound of settling time functional for the stabilization, which depends on the controller schemes and system parameters. Two illustrative examples and numerical simulations are given to validate the success of the derived theoretical results.     

Controlling chaotic Chua''s circuit based on piecewise quadratic Lyapunov functions method

In this paper, we present a linear feedback controller design method for controlling chaotic Chua's circuit based on piecewise quadratic Lyapunov functions. Firstly, we get the piecewise linear differential inclusions (pwLDIs) model of tracking error dynamics, then we design a linear state feedback controller to stabilize it based on the piecewise quadratic Laypunov functions. Finally, we give some numerical simulations to demonstrate the effectiveness of our theoretical results.     

Stability analysis of dynamic collaboration model with control signals on two lanes

In this paper, the influence of control signals on the stability of two-lane traffic flow is mainly studied by applying control theory with lane changing behaviors. We present the two-lane dynamic collaboration model with lateral friction and the expressions of feedback control signals. What is more, utilizing the delayed feedback control theory to the two-lane dynamic collaboration model with control signals, we investigate the stability of traffic flow theoretically and the stability conditions for both lanes are derived with finding that the forward and lateral feedback signals can improve the stability of traffic flow while the backward feedback signals cannot achieve it. Besides, direct simulations are conducted to verify the results of theoretical analysis, which shows that the feedback signals have a significant effect on the running state of two vehicle groups, and the results are same with the theoretical analysis.     

Optimal control of effort of a stage structured prey–predator fishery model with harvesting

This paper describes a prey–predator fishery model with stage structure for prey. The adult prey and predator populations are harvested in the proposed system. The dynamic behavior of the model system is discussed. It is observed that singularity induced bifurcation phenomenon is appeared when variation of the economic interest of harvesting is taken into account. We have incorporated state feedback controller to stabilize the model system in the case of positive economic interest. Fishing effort used to harvest the adult prey and predator populations is used as a control to develop a dynamic framework to investigate the optimal utilization of the resource, sustainability properties of the stock and the resource rent earned from the resource. Pontryagin’s maximum principle is used to characterize the optimal control. The optimal system is derived and then solved numerically using an iterative method with Runge–Kutta fourth-order scheme. Simulation results show that the optimal control scheme can achieve sustainable ecosystem.     

Multi-variable control of chaos using PSO-based minimum entropy control

The minimum entropy (ME) control is a chaos control technique which causes chaotic behavior to vanish by stabilizing unstable periodic orbits of the system without using mathematical model of the system. In this technique some controller type, normally delayed feedback controller, with an adjustable parameter such as feedback gain is used. The adjustable parameter is determined such that the entropy of the system is minimized. Proposed in this paper is the PSO-based multi-variable ME control. In this technique two or more control parameters are adjusted concurrently either in a single or in multiple control inputs. Thus it is possible to use two or more feedback terms in the delayed feedback controller and adjust their gains. Also the multi-variable ME control can be used in multi-input systems. The minimizing engine in this technique is the particle swarm optimizer. Using online PSO, the PSO-based multi-variable ME control technique is applied to stabilize the 1-cycle fixed points of the Logistic map, the Hénon map, and the chaotic Duffing system. The results exhibit good effectiveness and performance of this controller.     

Fractional order attitude stability control for sub-satellite of tethered satellite system during deployment

This paper investigates the sub-satellite attitude stabilization control of a tethered satellite system (TSS) during deployment stage. The dynamic model of sub-satellite motion is first established using Euler equations. During the tether deployment stage, the stability characteristics of attitude motion are analyzed with dissymmetric junction points between tether and sub-satellite. Then, a fractional-order attitude controller with memory ability is proposed to achieve stable control of the sub-satellite attitude, in which a dynamic model is linearized by using the feedback linearization method. Finally, validity of the fractional order controller and the advantages over an integer order controller are examined using numerical simulation. Comparing with the corresponding integer order controller, numerical simulation results indicate that the proposed sub-satellite attitude controller based on fractional order can not only stabilize the sub-satellite attitude, but can also respond faster with smaller overshoot.     

Controller design for stabilizing bilinear systems with state-based switching

Some nonlinear systems can be approximated by switching bilinear systems. In this paper, we proposed a method to design state-based stabilizing controller for switching bilinear systems. Based on the similarity between switching bilinear systems and switching linear systems, corresponding switching linear systems are obtained for switching bilinear systems by applying state-based feedback control laws. Instead, we consider asymptotically stabilizing the corresponding switching linear system through solving a number of relaxed LMI conditions. Stabilizing controllers for switching bilinear systems can be derived based on the results of the corresponding switching linear systems. The stability of the controller is proved step by step through the decreasing of the multiple Lyapunov functions along the state trajectory. The effectiveness of the method is demonstrated by both a theoretical example and an example of urban traffic network with traffic signals.     

Tracking control of chaotic spinning disks via nonlinear dynamic output feedback with input constraints

In many control engineering applications, it is impossible or expensive to measure all the states of the dynamical system and only the system output is available for controller design. In this study, a new dynamic output feedback control algorithm is proposed to stabilize the unstable periodic orbit of chaotic spinning disks with incomplete state information. The proposed control structure is based on the T‐S fuzzy systems. This investigation also introduces a new design procedure to satisfy a constraint on the T‐S fuzzy dynamic output feedback control signal. This procedure is independent of the exact value of initial states. Finally, computer simulations are accomplished to illustrate the performance of the proposed control algorithm. © 2015 Wiley Periodicals, Inc. Complexity 21: 148–159, 2016