Phase synchronization on asynchronous uniform rings with odd size

This paper proposes a self-stabilizing phase synchronization protocol for uniform rings with an odd size. Nodes in the ring work asynchronously and proceed in a cyclic sequence of K phases, where K is even. The phase values of all the nodes are required to be no more than one apart. A system state which satisfies the requirement is therefore called a legitimate state. The proposed protocol guarantees that no matter with which initial state the system may start, the ring stabilizes eventually at a state after which the closure property on the legitimate state holds. Phase values should never go backward. The closure property on the legitimate states commonly used in previous works on self-stabilization cannot capture this requirement. This paper defines two terms, legitimate step and illegitimate step, to address this issue. An execution step that brings the ring from a legitimate state to another legitimate state in a way that the phase values of the nodes only advance is called a legitimate step. An execution step that observes the closure property on the legitimate states but makes some phase values go backward is modeled as an illegitimate step. It is shown that, for the proposed protocol, only a finite number of illegitimate steps are possible. After all possible illegitimate steps have occurred, the closure property on the legitimate steps holds     

Self-stabilizing 2^m-clock for unidirectional rings of odd size

Summary. In this paper, we propose a self-stabilizing K-clock protocol for unidirectional rings with odd size, where and m is any positive integer. Besides the variable for maintaining the clock, the proposed protocol only requires one additional bit. The worst-case stabilizing time is ), where n is the ring size. Received: July 1998 / Accepted: January 1999     

Alternators on uniform rings of odd size

An alternator is a network of concurrent processes, which satisfies the following conditions. (1) If one process executes the critical step, no neighbor of the process executes the critical step in the same computing step. (2) Along any infinite computing steps, each process executes the critical step infinitely often. (3) An alternator is self-stabilizing to the above conditions. An alternator is said to be 1-fair if condition (2) is changed as: A process can execute the critical step twice only if all other processes execute the critical step at least once. In this paper, we proposed an alternator for rings of odd size. The design has the snap property in the sense that it satisfies condition (1) even when transient faults occur. The alternator allows each process execute the critical step once every three steps when it stabilizes. The design is optimal 1-fair in the sense that no other 1-fair design can have better performance. Based on the above design, we fine-tune the alternator to achieve maximal performance. That is, our final alternator is a maximal alternator: a process is allowed to execute the critical step when both its two neighbors do not execute the critical step.Received: September 2001, Accepted: December 2002, This research was supported in part by the National Science Council of the Republic of China under the Contracts NSC 89-2213-E-007-140 and 90-2213-E008-054.     

单向耦合混沌同步及其在保密通信中的应用

采用单向耦合同步法,利用Lyapunov稳定性定理、全局同步法及最大Lyapunov指数法分别对Lorenz系统、变形耦合发电机系统及超混沌Chen系统的自同步进行了研究.为适用于混沌保密通信,使用单路信号实现了驱动系统与响应系统的同步,并给出将超混沌Chen系统的自同步用于混沌掩盖保密通信的具体例子.数值模拟验证了所给方案的有效性.     

Asynchronous measurement and control: a case study on motor synchronization

The synchronization between two electrical motors (master and slave) is studied. To reduce the costs of the master–slave combination, the slave motor is mounted with a very low-resolution encoder (one pulse per revolution). Since the position measurements are asynchronous in time, standard control and analysis techniques are not applicable. Two methods are proposed to deal with these cheap, low-resolution encoders: the hybrid and the asynchronous control scheme. The presented controllers are successfully tested on a real industrial master-multi-slave system as is used for mailing machines.     

Strictly nonblocking grooming of dynamic traffic in unidirectional SONET/WDM rings using genetic algorithms

We propose a genetic algorithm (GA) to solve the strictly nonblocking grooming problems with dynamic traffic in unidirectional synchronous optical network/wavelength division multiplexing rings with arbitrary asymmetric traffic patterns. We give out the theoretical lower and upper bounds on the numbers of both add/drop multiplexers (ADMs) and wavelengths required and define the blocking properties in grooming dynamic traffic in detail. In applying GAs to this problem, we propose a first fit approach incorporated with a greedy local improvement algorithm to decode the chromosome. Four different local improvement scenarios are designed and compared in this paper. We also introduce the concepts of Link Load Imparity, Weighted Traffic Imparity and Average Link Load of each traffic pattern and use the latter two to estimate the first parameter before grooming. Comparison between the genetic and the random search results is also made. Computer simulation results show that it is important to combine the GA with an appropriate local improvement scenario in order to achieve near optimal results and to reduce the running time and that the algorithm proposed in this paper is able to achieve good results in reducing the numbers of ADMs and wavelengths.     

Scale-free brain ensemble modulated by phase synchronization

To listen to brain activity as a piece of music, we proposed the scale-free brainwave music （SFBM） technology, which could translate the scalp electroencephalogram （EEG） into music notes according to the power law of both EEG and music. In the current study, this methodology was further extended to a musical ensemble of two channels. First, EEG data from two selected channels are translated into musical instrument digital interface （MIDI） sequences, where the EEG parameters modulate the pitch, duration, and volume of each musical note. The phase synchronization index of the two channels is computed by a Hilbert transform. Then the two MIDI sequences are integrated into a chorus according to the phase synchronization index. The EEG with a high synchronization index is represented by more consonant musical intervals, while the low index is expressed by inconsonant musical intervals. The brain ensemble derived from real EEG segments illustrates differences in harmony and pitch distribution during the eyes-closed and eyes-open states. Furthermore, the scale-free phenomena exist in the brainwave ensemble. Therefore, the scale-free brain ensemble modulated by phase synchronization is a new attempt to express the EEG through an auditory and musical way, and it can be used for EEG monitoring and bio-feedback.     

时变耦合神经振子集群刺激依赖性相响应同步

考虑时变耦合情形下,利用相位响应曲线建立谐波刺激作用下耦合神经振子集群活动的动力学模型.引入相位概率密度函数导出描述神经振子集群活动序参数的演化方程.数值模拟结果表明高频谐波刺激可产生相位同步周期振荡,同步振荡周期与刺激频率有关,刺激频率越高神经振子群同步振荡频率也越高;同步强度与刺激强度有关,刺激越强同步程度越高.     

Modified projective phase synchronization of chaotic complex nonlinear systems

This paper introduces the concept of Modified Projective Phase Synchronization (MPPS) for interacting chaotic systems with complex variables. The idea is that the number of effective state variables can be increased by treating the real and imaginary parts separately. On the basis of the Lyapunov stability theory, a scheme is designed to realize the new form of chaotic synchronization, and we demonstrate how chaotic complex systems in a master–slave configuration can be synchronized to a constant scaling matrix. The speed and accuracy of the synchronization are illustrated by means of computer simulation.     

基于spikes-LFP相关性的相位同步化研究

神经系统的信息处理过程依赖于一种基本的神经机制-相位同步化.已往的研究表明单个神经元的spike与LFP构成同步化时会对应一个精确的相位,该相位能够对进一步处理信息以及与时间相关的可塑性产生影响.本文基于这项研究,提出了一种新颖的研究同步化现象的方法.运用该方法探索局部场电位(LFP)与神经元动作电位发放(Spikes)之间的相关性,该方法不仅能够保证数据分析的可靠性,而且在使用方面更简单、更具普遍性.     

绕线式异步电动机起动过程仿真研究

比较研究了三相绕线式异步电动机的在线直接起动、转子串可变电阻器起动和定、转子绕组双馈供电起动三种起动方法的起动性能。变转子电阻法是在起动时可变的三相电阻器接入转子电路并假定在起动过程中外接三相电阻可以连续变化以获得最大转矩。定、转子绕组双馈供电起动法是通过在预定的一个短时间内把定、转子绕组同时并联在同一个电源上而实现的。为了得到起动特性,建立了三相异步电动机在(d,q)静止坐标系下的动态数学模型,编制了仿真程序。通过实例对三相绕线式异步电动机的起动过程进行仿真计算,并对仿真结果进行比较分析,得出了一些有用的结论。     

Analysis of noise-induced phase synchronization in nervous systems: from algorithmic perspective

In many cases, a key step in neuronal information processing is phase synchronization of neurons (as oscillators). Substantial evidence suggests that an universal mechanism is behind the synchronization. Recently, stochastic equations were proposed to model the synchronization. However, it is unclear what force ultimately drives this universal mechanism. From algorithmic perspective, we analyze solutions of these stochastic equations. The result enhances the current analysis for the phase synchronization; importantly, it shows that noise is the ultimate driving force.     

全相位OFDM系统的最大自相关帧同步

针对数字地面广播电视（DTMB）系统,提出了一个对载波频偏具有鲁棒性的新的帧同步算法。该算法通过正交频分复用（OFDM）信号的时域复制和对接收信号实行自相关来实施。自相关数值输出的非关联求和的峰值检测是理所当然的帧起始点。理论证明,载波频率偏移（CFO）对全相位自相关帧同步算法没有影响。通过仿真表明,在频率选择性衰落信道中,提出的方法在有频偏存在情况下比传统算法具有很强的优势,对于DTMB系统的PN420模型,系统保持稳定工作的最大CFO在所提方法中要远远大于传统的方法。     

Emotion recognition based on sparse representation of phase synchronization features

Emotion recognition based on Electroencephalogram (EEG) has attracted much attention in brain-computer interaction. However, most existing methods usually focus on amplitude and spectrum of the EEG signal, leading to sub-optimal performances due to the insufficiency in modelling the complex intrinsic information of neural integration. To address this issue, this paper proposes to capitalize on the largely neglected phase synchronization (PS) between EEG channels which reflects the intrinsic rhythmic interactions between different channels in neural integration. Specifically, this paper develops a simple and novel feature extraction method which calculates the PS based sparse representation features to analyze emotion states. First, the EEG phase synchronization indexes (PSI) of all channel pairs are estimated as features to distinguish different emotions, since certain topographical maps on PSI reveal specific emotion states. Then principal component analysis is performed to eliminate redundant and noisy features in PSI. Finally, Sparse Representation based Classification (SRC) furtherly emphasize emotion-related features and restrain useless features. For the benchmark affective EEG dataset DEAP, the proposed method based on no-overlapping EEG features achieve an average accuracy of 94.5%, 87.61%, and 67.04% for the classification tasks respectively on two, three and four emotions, demonstrating the superiority over state-of-the-art emotion classification methods.

     

基于均匀十字阵的幅相误差自校正算法

针对实际应用中普遍存在的幅相误差扰动问题,结合子空间类波达方向估计算法,基于均匀十字阵列,提出了一种幅相误差的自校正算法。均匀十字阵列可分解为两个相互垂直的均匀线性阵列,利用均匀线阵接收数据协方差矩阵的结构特点对幅相误差进行初步估计,计算出波达方向的初始估计值,通过迭代方法得到更精确的估计值,自校正方法不需要任何参数初始值,实现比较简单。仿真实验验证了算法具有良好的误差校正效果,能够比较准确地估计出信源的波达方向角和阵元的幅相误差值。     

基于高精度相频同步的节点端无损切换技术研究

随着网络化高精度固定节点时频同步技术的发展,需要对簇节点端多输入信号进行处理。针对簇节点端多输入信号同源多路径的特性,为了提升系统的稳健性,提出了一种信号无损切换的方法,兼顾了开关的隔离度和切换速度;实现了主备路信号ps量级的同步精度,有效抑制了切换过程中的相位跳变,并对不同条件下的主备路相位同步精度、系统无损切换性能进行了仿真实验。仿真结果表明,提出的方案显著提升了主备路相位同步精度,有效抑制了切换过程中产生的相位跃变,验证了不同条件对系统精度的影响,对节点端无损切换乃至信号融合方面具有很大的借鉴意义。     

CORBA中的异步传输机制

近几年来，随着Internet的发展，跨异步系统计算机分布式计算成为未来的发展趋势，CORBA技术为此提供了一套完整的体系结构，同时也完成了从研究走向应用的步骤。本文主要讨论了的CORBA的异步传输机制ONEWAY以及事件服务。同时给出用DELPHIL利用ONEWAY以及事件服务异步传输机制实现的简单模型。     

基于锁相环的水听器阵列多传感器高精度同步技术

针对水听器阵列中多个传感器采集信号的同步问题,提出了一种适合于水听器阵列结构特点的高精度同步方法。该方法采用两级同步的方式:首先运用锁相环技术,保证同一个节点内多个传感器之间的同步采集;然后采用传输延时补偿的方法来补偿不同节点间的传输延时所引起的同步误差,实现节点之间的高精度同步采集。建立了一个实验系统:它由一个主节点和两个从节点组成。测试结果表明,同一节点内的同步采集误差不大于5 ns,不同节点间的同步采集误差不大于10 ns。对样机系统进行了进一步测试,测试结果与实验系统的测试结果一致。测试结果表明,该方法能实现水听器阵列多传感器间的高精度同步采集。