离散非完整链式系统的镇定

针对定常采样过程中非完整链式系统的镇定问题,提出了2个反馈控制律.首先通过对连续模型的积分运算,得到了零阶保持器下非完整链式系统的离散模型,然后利用坐标变换,将其转换为2个线性子系统的形式,并提出了2种反馈镇定控制律:时不变反馈控制律和时变反馈控制律,分别实现了对离散非完整链式系统的局部和全局镇定.仿真实验表明所提反馈控制律是行之有效的.在它们的作用下,离散非完整链式系统能从任意的初始状态指数收敛到原点,并且通过改变反馈控制律的参数能改变系统各状态的收敛速度.     

电力市场中一类博弈模型的脉冲延迟反馈控制法

针对电力市场中一类非线性博弈模型的混沌问题,通过加入脉冲时间延迟反馈控制,对其稳定性进行研究。第一种形式是对一家投资商引入系统变量的时间延迟反馈控制法,第二种形式是对整个系统引入系统变量的时间延迟反馈控制,并利用Matlab软件对该系统进行数值模拟,验证该方法的有效性。结果表明：时间延迟反馈控制可以有效控制系统的稳定性。     

一方不能独立生存的非自治偏利合作模型研究

提出并研究一类一方不能独立生存的非自治偏利合作模型。借助微分方程比较原理探讨了系统的绝灭性和持久性问题,结果表明在合作效益较小时,种群将仍然绝灭,而在合作效益足够大后,两个种群都能持久生存;在持久的情形下,通过构造适当的Lyapunov函数分别得到一组保证系统正解全局吸引的充分性条件。     

广义周期时变系统的状态反馈允许性分析

研究了广义周期时变系统的状态反馈允许性问题.设计状态反馈控制器使闭环系统正则,无脉冲且渐近稳定,利用矩阵不等式方法导出系统在状态反馈控制作用下允许的充分必要条件,并给出控制器的设计方法.     

Chen-Lee混沌系统的控制与同步

根据Routh-Hurwitz准则判断Chen-Lee混沌系统平衡点的稳定性,并设计简单的反馈控制将系统的混沌状态控制到稳定状态。采用线性反馈控制实现了驱动-响应Chen-Lee混沌系统间的混沌同步。数值模拟验证了该方法是可行的。     

具有反馈控制的非自治两种群浮游生物相克系统的持久性

研究一类具有反馈控制的非自治两种群浮游生物相克系统．借助干微分方程的比较原理和一个积分不等式,得到了一组保证系统持久的充分性条件．结果表明在原系统持久下,反馈控制变量对系统的持久性没有影响．所得结果说明文献[2]的持久性条件中有关反馈控制变量的条件限制是多余的,由此实质性地改进了文献[2]的结果．     

具有反馈控制和时滞的两企业竞争与合作离散模型的持久性

研究一类具有反馈控制和时滞的两企业竞争与合作的离散模型.运用差分不等式的有关理论,得到保证该系统持久的充分性条件.所得结论表明在适当条件下,反馈控制变量对该系统的持久性没有影响.     

四种自动控制系统的比较

基于活性污泥法的二级污水处理工艺中投入应用和正在研究的自动控制系统从控制模式上分类,大致有以下几种:时序控制、反馈控制、多重反馈控制、智能控制.     

捕食者具有反馈控制的Leslie-Gower捕食-食饵模型的稳定性研究

研究一类捕食者具有反馈控制的Leslie-Gower捕食食饵模型,通过构造Lyapunov函数方法,可以得到系统的唯一正平衡点是全局稳定的结论.这表明反馈控制变量只改变平衡点的位置-捕食者密度增加而食饵密度降低,但不会改变系统的稳定性态.     

频段内汽车悬架时滞反馈控制参数优化

对有限频段内汽车悬架系统的时滞反馈控制参数优化问题进行研究。首先,建立时滞加速度反馈控制下 1/4 汽车悬架系统力学模型,推导出车身和车轮加速度幅值的解析表达式;其次,通过对系统稳定性分析,得到关于反馈增益系数和时滞的稳定性分区图,以数值计算验证稳定性分析的正确性;最后,在有限频段内以最大车身加速度变化的百分比为优化目标,以反馈增益系数和时滞为优化参数,利用粒子群优化算法获得有限频段内最优反馈增益系数和时滞。实验结果表明,与被动汽车悬架系统相比较,最优时滞反馈控制下汽车悬架系统的隔振性能获得了明显提高,在最优时滞反馈控制参数取值下,有限频段内车身加速度幅值至少降低37.27%。     

Effects of exteroceptive feedback and safe-box confinement durations on escape behavior in rats

In Experiment 1, rats received escape training in which an exteroceptive feedback cue occurred in the safe box, and safe-box confinement durations of 5 or 20 sec were combined orthogonally with shock-box confinement durations of 5 or 20 sec. Exteroceptive feedback reliably facilitated escape performance relative to no-feedback controls when safe-box confinement was relatively longer than shock-box confinement. Confinement duration also facilitated performance in the absence of exteroceptive feedback. In Experiment 2, escape training with or without feedback was followed by extinction either with the feedback condition of prior training or with the opposite feedback condition. Feedback presentations in extinction reliably increased responding. Feedback removal reliably decreased responding relative to feedback controls. Introduction of feedback in extinction reliably enhanced performance relative to no-feedback controls.     

Effects of duration of feedback on signaled avoidance

Two experiments were carried out to study vertical jumping avoidance learning in rats. In particular, we examined the effects of the duration of a feedback stimulus and of the interval between the end of the feedback stimulus and the start of the next trial on acquisition and extinction of avoidance. In Experiment 1, the duration of feedback was manipulated while intertriai interval (feedback plus no-feedback) was held constant. Animals with feedback lasting more than 1 sec needed fewer trials to reach the acquisition criteria than did animals with no feedback or with 1-sec feedback. No differences were observed in extinction. In Experiment 2, the durations of both feedback and no-feedback were manipulated. Animals without feedback needed more trials to reach the acquisition criterion than did animals with feedback, but the performance of the feedback animals did not differ as a function of feedback duration, no-feedback duration, or total intertrial interval. Again, no differences were observed in extinction. These results indicate that the presentation of feedback improves the acquisition of vertical jumping avoidance, but that this effect is independent of the temporal characteristics of feedback.     

BACKWARD WELLPOSEDNESS OF NONUNIFORM TIMOSHENKO BEAM EQUATION

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Backward wellposedness of nonuniform Timoshenko beam equation

In this paper, we consider the Timoshenko equation of a nonuniform beam, with clamped boundary condition at one end and with feedback controls at the other end. It is proved that the system is backward wellposedness when the feedback controls are weak enough. Project supported partially by the National Key Project of China and the Natural Science Foundation of China (No. 69874034).     

Taste quality and extinction of a conditioned taste aversion in rats

Rats (Rattus norvegicus) that received a taste cue (saccharin, saline, quinine, or sucrose) paired with a lithium chloride (LiCl) injection displayed a robust decrease in consumption of that taste, relative to controls that had the taste unpaired with LiCl. Consumption of the paired taste increased with each nonreinforced presentation (i.e., extinction). After asymptotic extinction, rats that had had a 0.1% saccharin cue paired with LiCl consumed less of the saccharin solution than did controls. A similar data pattern was observed with a 10% sucrose solution. These results are consistent with the view that some aspect of the excitatory CS-US association remains after extinction. On the other hand, rats that had a bitter (0.005% or 0.001% quinine) or salty (1% or 0.5% saline) solution paired with LiCl drank similar amounts of the fluid as controls after asymptotic extinction treatment. Together, these experiments suggest that a taste that is either sweet or preferred is required in order to demonstrate the chronic decrease in fluid consumption after extinction treatment. The data suggest that the conditioning experience prevents the later development of a preference for the sweet taste, rather than there being a retained aversion that suppresses fluid consumption.     

具阶段结构反馈控制Lotka-Volterra系统的局部稳定性

提出了具阶段结构反馈控制Lotka—Voherra竞争模型,得到保证该模型存在局部稳定非负平衡点的充分性条件．     

既具有反馈控制又具有厌食反应和疾病传染的捕食系统的持续生存性与周期解

利用微分不等式和通过构造适当的Lyapunov函数,讨论了一类既具有反馈控制又具有厌食反应和疾病传染的周期捕食系统的持续生存性以及周期解的存在性,唯一性和稳定性问题,得到了一些新的结果.     

具无穷时滞反馈控制竞争模型的全局吸引性的注记

研究了两种群具有无穷时滞反馈控制竞争模型的正平衡点的全局吸引性，通过构造单调递归序列的方法得到该模型存在全局吸引正平衡点的充分性条件．     

具有反馈控制的Schoener模型的渐近周期解

考虑了具有反馈控制的非自治Schoener竞争生态系统。通过建立相应的伴随系统和构造合适的Liapunov函数,得到了该系统唯一存在正的全局渐近稳定的渐近周期解的充分条件。