用于宽带啁啾脉冲光参量放大系统精确同步的新方法

基于非共线光参量放大,以波长800 nm飞秒激光的倍频光为抽运光,以激光二极管640 nm连续波激光为信号光,产生了与800 nm飞秒激光精确同步的无直流本底的1064 nm脉冲光。实验结果显示该1064 nm的光脉冲在脉冲能量和空间光束质量上均可作为1064 nm波长脉冲放大器的种子光。仅通过一级简单紧凑的非共线参量放大就可实现光周期量级的光参量啁啾脉冲放大系统的抽运激光和种子光的精确同步。     

两个四维混沌系统广义投影同步

利用主动控制同步法设计合适的非线性反馈控制器，实现两个相同的四维混沌系统的同结构广义投影同步，以及实现两个不同的新型四维混沌系统异结构广义投影同步.通过改变广义投影同步的比例因子，获得任意比例于原驱动混沌系统输出的混沌信号.数值仿真表明了所设计的控制器有效性和理论推导的正确性.     

Inverse chaos synchronization between bidirectionally coupled variable multiple time delay systems

We make first report on inverse chaos synchronization between bidirectionally non-linearly and linearly coupled variable multiple time delay laser systems governed by the Ikeda model. The results are of certain importance in secure chaos-based communication systems.     

Steepest-descent method-based adaptive frequency domain equalizer in coherent optical orthogonal frequency division multiplexing with quadrature phase shift keying modulation

An adaptive frequency domain equalizer (A-FDE) in quadrature phase shift keying-coherent optical-orthogonal frequency division multiplexing (QPSK-CO-OFDM) system is proposed in this paper. A-FDE uses steepest descent method to search the optimal equalization parameters. And through applying the adaptive control factor (ACF) to monitor the state of A-FDE, the interference from phase noise (PN) and chromatic dispersion (CD) can be mitigated. The numerical simulation shows that the performance of A-FDE has a remarkable improvement on combating PN and CD comparing with the conventional decision-directed equalizer (DDE). And the A-FDE can achieve the forward-error-correction (FEC) threshold in noisier scenario. Furthermore, because the calculation of ACF only bases on valid data instead of pilot symbols (PSs), A-FDE has low PS overhead merit.     

Finite-time lag synchronization of coupled reaction–diffusion systems with time-varying delay via periodically intermittent control

In this paper, the issue of finite-time lag synchronization of coupled reaction–diffusion systems with time-varying delay (CRDSTD) is considered. A periodically intermittent controller is designed such that drive system and corresponding response system can achieve finite-time lag synchronization. By using graph theory and Lyapunov method, two sufficient criteria are presented to guarantee the finite-time lag synchronization of CRDSTD. Moreover, the time of achieving lag synchronization of CRDSTD is estimated. Finally, a numerical example is given to show the effectiveness of the proposed results.     

Difference systems of sets and cyclotomy

Difference systems of sets (DSS) are combinatorial configurations that arise in connection with code synchronization. A method for the construction of DSS from partitions of cyclic difference sets was introduced in [V.D. Tonchev, Difference systems of sets and code synchronization, Rend. Sem. Mat. Messina, Ser. II, t. XXV 9 (2003) 217–226] and applied to cyclic difference sets (n,(n-1)/2,(n-3)/4) of Paley type, where is a prime number. This paper develops similar constructions for prime numbers that use partitions of the set of quadratic residues, as well as more general cyclotomic classes.     

Synchronization of neural networks based on parameter identification and via output or state coupling

For neural networks with all the parameters unknown, we focus on the global robust synchronization between two coupled neural networks with time-varying delay that are linearly and unidirectionally coupled. First, we use Lyapunov functionals to establish general theoretical conditions for designing the coupling matrix. Neither symmetry nor negative (positive) definiteness of the coupling matrix are required; under less restrictive conditions, the two coupled chaotic neural networks can achieve global robust synchronization regardless of their initial states. Second, by employing the invariance principle of functional differential equations, a simple, analytical, and rigorous adaptive feedback scheme is proposed for the robust synchronization of almost all kinds of coupled neural networks with time-varying delay based on the parameter identification of uncertain delayed neural networks. Finally, numerical simulations validate the effectiveness and feasibility of the proposed technique.     

外噪声作用下可激发系统中的预测同步现象

采用数值模拟方法研究了由2个完全相同的可激发系统,通过单向延迟反馈耦合连接所组成主动-从动系统中的预测同步现象.结果表明在相等的外噪声作用下,当延迟时间和耦合强度在适当的范围内取值时,从动系统发生放电活动时所产生的动作电位能够预测主动系统发生放电活动时所产生的动作电位,即出现了预测同步现象,并且预测时间不可能大于主动神经元的响应时间.     

Testing the accuracy of employee-reported data: An inexpensive alternative approach to traditional methods

Although Information Technology (IT) solutions improve the collection and validation of operational data, Operations Managers must often rely on self-reported data from workers to make decisions. The problem with this data is that they are subject to intentional manipulation, thus reducing their suitability for decision-making. A method of identifying manipulated data, digital analysis, addresses this problem at low cost. In this paper, we demonstrate how one uses this method in real-world companies to validate self-reported data from line workers. The results of our study suggest that digital analysis estimates the accuracy of employee reported data in operations management, within limited contexts. These findings lead to improved operating performance by providing a tool for practitioners to exclude inaccurate information.