Unique Periodic Orbits for Delayed Positive Feedback and the Global Attractor

The delay differential equation, (t)=–x(t)+f(x(t–1)), with >0 and a real function f satisfying f(0)=0 and f>0 models a system governed by delayed positive feedback and instantaneous damping. Recently the geometric, topological, and dynamical properties of a three-dimensional compact invariant set were described in the phase space C=C([–1, 0], ) of initial data for solutions of the equation. In this paper, for a set of and f which include examples from neural network theory, we show that this three-dimensional set is the global attractor, i.e., the compact invariant set which attracts all bounded subsets of C. The proof involves, among others, results on uniqueness and absence of periodic orbits.     

Analysis of queuing delay in optical space network on LEO satellite constellations

Low earth orbit (LEO) satellite constellations using laser inter-satellite links (ISLs) are recognized as a promising technology to provide global broadband network services. In this paper, the queuing delay model of an optical space network built on LEO satellite constellations is established. It is assumed that the optical space network employs wavelength division multiplexing ISLs with wavelength routing technology to communication satellites and makes routing decisions. With consideration of the network task characterizations such as distribution of task arrival time and task holding duration, simulation experiment results are analyzed and the expression of optical space network queuing delay is given. Both theoretical analysis and simulation results show that features of queuing delay vary with distribution characterizations of the network tasks. It is hoped that the study can be helpful to evaluate the design of constellation networking.     

基于路径相关性的电路小延时缺陷检测算法

在基于纳米技术的现代电路中,小延时缺陷(SDDs)检测是个重要问题,即使这些SDD缺陷没有导致功能性故障,但也是一种可靠性隐患,如果工艺发生变化,这些缺陷的检测更为困难;文章提出一种基于电路路径延时相关性的SDD缺陷检测算法,即使工艺发生变化也可以检测出SDD缺陷;该算法利用了如下原理:对两个高度相关的路径,一条路径的延时方差的重要部分可以用另一条路径的延时方差进行描述;另外,考虑了空间和结构相关性及随机掺杂波动,开发并部署了一种统计学计时分析框架,以计算时间信息和跨径相关性(IPC);基于74LS85和ISCAS85基准电路的仿真结果验证了算法的可行性。     

Wideband slow light achievement in MIM plasmonic waveguide by controlling Fano resonance

In this paper, we have investigated the characteristics of an asymmetric shaped Fano line in a metal–insulator–metal (MIM) plasmonic waveguide side coupled to two resonating stub structures. The spectral properties of Fano resonance are quite distinct due to the destructive interference between a two propagating plasmon modes. Two structural parameters are carefully adjusted: physical separation between both the resonating stubs and length of resonating stubs. By tailoring the separation between both the resonating structures, coupling between both the plasmon modes is controlled, and hence asymmetric nature of Fano line can be shaped accordingly. Resonance condition of Fano line can be tuned by scaling the length of stubs. A strong red shift in resonating wavelength with varying degree of asymmetry is observed, when length of resonating structures is increased. The sharp resonant peak, due to an asymmetric shaped Fano resonance is generally accompanied by large dispersion that results in reduction of group velocity of light near Fano resonance. By controlling the coupling between resonating stub, or by scaling the length of lower resonating stub, large value of group index (n_g = 75) and delay bandwidth product (DBP = 0.2533) is obtained. The structure can be modified to suit different applications in optical buffers, optical switches and nonlinear optics devices.     

细胞外钾离子浓度延迟恢复对螺旋波的影响研究

在Luo-Rudy相I心脏模型中考虑了细胞外钾离子浓度的频率依赖性,并研究了细胞外钾离子浓度的延迟恢复对螺旋波动力学的影响.数值模拟结果表明,在螺旋波态下,细胞外钾离子浓度的延迟恢复会导致细胞外钾离子浓度周期振荡,其振荡周期和振幅随延迟恢复时间的增加而增加,进而导致出现呼吸螺旋波、多螺旋波共存、螺旋波做Lévy飞行式漫游、螺旋波通过不同方式消失等现象,这些结果与实验结果一致.     

时滞惯性神经网络的稳定性和分岔控制

针对一类二阶时滞惯性神经网络模型,提出一种基于时滞反馈的分岔控制方法.利用时滞微分方程动力学理论,给出反馈控制系统的稳定性以及发生Hopf分岔的判别条件.数值仿真显示所设计的控制器不仅能有效延迟网络分岔的发生,还能扩大稳定域并改善网络的收敛速度.     

频域光学相干层析术系统中高准确度高灵敏度补偿色散法

将色散测量方法和快速扫描延迟线技术相结合,在谱域光学相干层析系统中实现了对群延迟色散的精确补偿.在该方法中,先在样品臂中放入平面反射镜,等间隔移动参考臂中快速扫描延迟线系统中光栅的位置,同时测量系统参考臂和样品臂之间的群延迟色散差值.当该值为零时,则表明系统色散匹配.将该方法与基于点扩散函数半高宽的方法进行比较,发现基于半高宽方法的测量误差为4.43%,而该方法的测量误差为0.76%;在色散补偿过程中,随着色散匹配点的靠近,半高宽方法的灵敏度由92.105 3fs2减小到1.344 7×103 fs2,而新方法的灵敏度则保持165.789 5fs2,表明本文提出的色散补偿法具有较高的色散补偿准确度和灵敏度.实验表明,色散补偿后的系统分辨率接近理论值;在补偿系统色散的同时,还可以根据测量所得色散值的符号来判定光栅的移动方向,从而更容易地完成补偿工作.     

State estimation of memristor‐based recurrent neural networks with time‐varying delays based on passivity theory

This article deals with the state estimation problem of memristor‐based recurrent neural networks (MRNNs) with time‐varying delay based on passivity theory. The main purpose is to estimate the neuron states, through available output measurements such that for all admissible time delay, the dynamics of the estimation error is passive from the control input to the output error. Based on the Lyapunov–Krasovskii functional (LKF) involving proper triple integral terms, convex combination technique, and reciprocal convex technique, a delay‐dependent state estimation of MRNNs with time‐varying delay is established in terms of linear matrix inequalities (LMIs). The information about the neuron activation functions and lower bound of the time‐varying delays is fully used in the LKF. Then, the desired estimator gain matrix is accomplished by solving LMIs. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed theoretical results. © 2013 Wiley Periodicals, Inc. Complexity 19: 32–43, 2014     

超负荷服务运作系统下的等待延迟通告决策研究

以超负荷运作服务系统为研究对象,考虑顾客止步或中途放弃带来的损失,及顾客等待和被服务所带来的收益,以最大化期望收益为目标,研究如何在顾客到达时做出等待延迟通告决策.构建了基于顾客行为的服务运作系统等待延迟通告决策模型,分析各种情况下的最优解.并通过对各参数的敏感性分析得到一系列有意义的决策和管理建议.     

一类具非线性发生率和垂直传染的流行病模型分析

研究了一类具非线性发生率和垂直传染的SEIR传染病模型,在模型中考虑了时滞和脉冲免疫接种,运用离散动力系统的频闪映射,获得了一个无病周期解,并得到了无病周期解全局吸引的条件,运用脉冲时滞泛函微分方程理论,获得了含有时滞的模型持久性的充分条件.