Numerical analysis on car-following traffic flow models with delay time

INTRODUCTION For the past few decades, many researchers have made studies of modelling driver behavior to repro- duce the observed features of traffic flow. Recently Kerner and Rehborn (1997) observed that there are three distinct dynamic phases on highways: free traf- fic flow, coexisting traffic flow and traffic jams. The occurrence of traffic jams without obvious reasons had been explained in terms of the conventional phase transition (Nagatani, 1998). Various traffic flow models, suc…     

一类时滞不确定系统的鲁棒稳定性研究

本文针对一类带时滞的时变不确定系统,在其他文献研究的基础上提出一种鲁棒控制设计方法.这种方法在知道时滞的区间而不知时滞的准确量的情况下,就可以设计相应的控制器而保证系统的稳定性.最后,用事例验证了方法的有效性.     

交通信号实时控制优化模型与算法

通过对交叉路口交通流到达和排队延误规律的研究,提出了一种新的交通信号控制理论,并建立了以PI值最小为目标的交通信号配时优化理论模型。该信号配时方法与通常采用的单点自适应信号控制方法的区别在于不但考虑了交通延误,而且考虑了停车次数,实现了对交通延误和停车次数两指标的优化,从而保证了以车队形式到达的交通流可以不间断地通过交叉路口。由于以实时交通流的到达规律为依据进行信号优化配时,因此,该信号配时优化模型又是实时自适应交通信号控制优化模型。     

一类具有时滞病毒模型的Hopf分支

利用时滞微分方程理论与Hopf分支的相关理论,对一类具有时滞的流感病毒模型进行了研究,对其惟一的正平衡点,给出了其存在Hopf分支的条件和分支方向.     

具有时滞补偿的网络拥塞控制的研究

经过线性化处理的TCP/AQM拥塞控制模型是一个输入带有时滞的源端链路端组合系统。首先修改了带有延迟的网络拥塞控制模型;计算其平衡状态并进行线性化,采用积分变换算法进行延迟变换为无时滞的线性模型,并建立相应的状态空间模型。在模型矩阵参数抖动但有界限的条件下,应用变结构控制算法设计控制器,基于李雅普诺夫稳定性理论和线性矩阵不等式方法给出了该控制器控制的系统可到达和渐进稳定的可行条件,同时根据该条件设计网络链路端主动队列管理算法。最后,仿真结果表明了该算法的有效性。     

航班延误时间序列的混沌特征分析及短时预测

针对航班延误时间序列的混沌特性,建立基于极限学习机(extreme learning machine, ELM)的混沌短时预测模型,对机场航班延误状况进行预测。首先,结合某枢纽机场2018年进离场航班延误架次、延误率和平均延误时长等航班延误状况时间序列,运用小数据量法对序列进行混沌识别;进而,根据递归图理论分析序列的混沌特征,并进行序列的可预测分析;最后,建立基于ELM的混沌预测模型对不同航班延误状况进行预测。结果表明:6个航班延误状况时间序列均符合混沌特性;进场航班延误架次的可预测性最高,进、离场航班平均延误时间长的可预测性均较低;通过本文预测方法对进、离场航班延误架次的预测效果较佳,均方根误差分别为4.520 9和4.524 3,证明该预测方法有效、可行。     

一类具有时滞和Michaelis-Menten型收获的捕食系统的稳定性与Hopf分支分析

探讨了一类具有时滞和非线性Michaelis-Menten型收获的捕食系统.利用微分方程的稳定性理论和Hopf分支理论,研究模型的动力学行为.分析了系统存在唯一正平衡点的条件,系统正平衡点渐近稳定的条件,并且给出了滞量作为参数时存在临界值使系统在一定范围内正平衡点仍保持稳定,而在其等于临界滞量时系统在正平衡点处出现Hopf分支的结论.     

MATLAB在时滞过程Smith预估控制特性研究中的应用

该文介绍了Smith预估器存在的问题，利用MATLAB的Simulink工具箱对Smith预估控制系统的特性进行了仿真研究，定量给出了参数不匹配而Smith预估控制仍然具有较好的控制效果的参数范围，指出了τp／Tp对Smith预估控制鲁棒性的影响，通过模拟实验，增强了学生对Smith预估控制的理解，为今后从事相关研究和在实际系统中应用Smith预估控打下了基础。     

Use of constant time delay and attentional responses with adolescents

This study investigated the effectiveness of a constant time delay procedure in teaching adolescents with learning or behavior disorders. Subject matter included social studies and health facts presented in small-group settings. In addition, the study assessed the effects of two attentional responses (general--looking at the target stimuli, or specific--repeating the teacher's question) on students' acquisition of other students' facts and of related nontarget information. Two types of feedback for correct responses were presented: praise plus additional information, and general praise only. Results of various measures indicate that (a) the constant time delay procedure was reliable and effective; (b) students not only acquired targeted facts with few errors, but also acquired some other nontargeted facts, such as information presented along with feedback; and (c) specific attentional responses facilitated acquisition of observational and incidental facts and maintenance of learning.     

Bending behavior of double-row stabilizing piles with constructional time delay

The bending behavior of double-row stabilizing plies is associated with the constructional time delay (CTD), which can be defined as the time interval between the installations of the front stabilizing pile and the rear stabilizing pile. This paper investigates the effect of CTD on the bending moments of double-row stabilizing piles and a method for determining the optimal CTD is proposed. The stabilizing pile is modeled as a cantilever pile embedded in the Winkler elastic foundation. A triangular distributed earth pressure is assumed on the pile segment in the sliding layer. The front stabilizing pile and the rear stabilizing pile are connected by a beam with pinned joints. The analytical solutions of bending moments on the front and the rear stabilizing piles are derived and the accuracy of bending moment solutions is validated by comparing the tensile strain measured from the Hongyan landslide project, Taizhou, Zhejiang, China. It is concluded that CTD has a significant influence on the bending moments of double-row stabilizing piles. An optimal CTD can be obtained when the maximum tensile stress in the front stabilizing pile is equal to that in the rear stabilizing pile, which is 1.4 months for the Hongyan landslide project.     

递归响应法对磁流变阻尼结构的时滞补偿

控制系统中的时滞现象是影响控制效果的不可忽视的因素。文章采用递归响应法对磁流变阻尼控制系统的算法进行仿真计算,分析在不同情况下递归响应法对磁流变阻尼控制系统的时滞补偿效果,并与主动控制系统进行比较。结果表明,递归响应法对磁流变阻尼控制系统有一定的补偿效果,对主动控制系统效果更加显著。     

Stability analysis of CPLL with loop delay

In this paper,a discrete-time analysis of the third-order charge-pump based phase-locked loops (CPLLs) is presented in the presence of loop delay.The z-domain analysis of the closed-loop transfer function is derived and compared with the traditional s-domain method.The simulation results under SPECTRE show that,due to the sampling nature of CPLL,the traditional s-domain analysis is unable to predict its jitter peaking accurately,especially when the loop delay is taken into consideration.The impact of loop delay on the stability of the third-order CPLL system is further analyzed based on the proposed way.The stability limit of the wide bandwidth CPLL with loop delay is calculated.The circuit simulation results agree well with mathematical analysis.     

n维时滞Lotka-Volterra型竞争系统正周期解的存在性

运用重合度理论中的连续性定理研究了n维时滞Lotka-Volterra型竞争系统正周期解的存在性,得到了该模型存在正周期解的一个充分条件.     

Delay-dependent robust H∞ control for a class of uncertain switched systems with time delay

For linear switched system with both parameter uncertainties and time delay,a delay-dependent sufficient condition for the existence of a new robust H∞ feedback controller was formulated in nonlinear matrix inequalities solvable by an LMI-based iterative algorithm.Compared with the conventional state-feedback controller,the proposed controller can achieve better robust control performance since the delayed state is utilized as additional feedback information and the parameters of the proposed controllers are changed synchronously with the dynamical characteristic of the system.This design method was also extended to the case where only delayed state is available for the controller.The example of balancing an inverted pendulum on a cart demonstrates the effectiveness and applicability of the proposed design methods.     

IVFS理论的一种新刻画

给出了IVFS[α1，α2]-上(下)截集．并讨论了它们的基本性质，在此基础上建立了一系列分解定理．从而重新刻画了IVFS理论．     

A signal detection analysis of contingency data

There are many psychological tasks that involve the pairing of binary variables. The various tasks used often address different questions and are motivated by different theoretical issues and traditions. Upon closer examination, however, the tasks are remarkably similar in structure. In the present paper, we examine two such tasks, the contingency judgment task and the signal detection task, and we apply a signal detection analysis to contingency judgment data. We suggest that the signal detection analysis provides a novel interpretation of a well-established but poorly understood phenomenon of contingency judgments-the outcome-density effect.     

非线性多变延迟奇异摄动问题的稳定性分析

讨论了形如x′(t) =f(x(t) ,x(t -τ1(t) ) ,… ,x(t -τm(t) ) ,y(t) ,y(t -τ1(t) ) ,… ,y(t-τm(t) ) )和εy′(t) =g(x(t) ,x(t -τ1(t) ) ,… ,x(t -τm(t) ) ,y(t) ,y(t -τ1(t) ) ,… ,y(t -τm(t) ) ) (0 <ε 1)的非线性多变延迟奇异摄动系统的理论解的稳定性 ,得到了系统稳定的一个充分条件 .在此条件下还证明了隐式Euler方法的数值解是稳定的 .     

一种新的决策评价模型及其变权分析

构建了一个多指标、多因素、多属性的综合决策和评价模型.该模型先计算方案在单纯形上的局部满意度,再根据其总量值计算全局满意度；既考虑了各属性的重要程度,也考虑了各指标间相互关系、相互制约的特征.最后采用实验从梯度和变权角度分析其有效性及隐含变权思想.     

地方高校教师在岗培训的新途径

在我国高等教育大众化快速发展时期,地方高校师资呈快速增长态势.为提高教学质量,青年教师在岗培训成为一个重要问题.本文分析了地方高校原有教师在岗培训方式的弊端及其原因,提出了地方高校教师为适应大众化教育发展要求的在岗培训新途径.