Random shortcuts induce phase synchronization in complex Chua systems

This paper studies how phase synchronization in complex networks depends on random shortcuts, using the piecewise-continuous chaotic Chua system as the nodes of the networks. It is found that for a given coupling strength, when the number of random shortcuts is greater than a threshold the phase synchronization is induced. Phase synchronization becomes evident and reaches its maximum as the number of random shortcuts is further increased. These phenomena imply that random shortcuts can induce and enhance the phase synchronization in complex Chua systems. Furthermore, the paper also investigates the effects of the coupling strength and it is found that stronger coupling makes it easier to obtain the complete phase synchronization.     

Identification of denatured and normal biological tissues based on compressed sensing and refined composite multi-scale fuzzy entropy during high intensity focused ultrasound treatment

In high intensity focused ultrasound(HIFU)treatment,it is crucial to accurately identify denatured and normal biological tissues.In this paper,a novel method based on compressed sensing(CS)and refined composite multi-scale fuzzy entropy(RCMFE)is proposed.First,CS is used to denoise the HIFU echo signals.Then the multi-scale fuzzy entropy(MFE)and RCMFE of the denoised HIFU echo signals are calculated.This study analyzed 90 cases of HIFU echo signals,including 45 cases in normal status and 45 cases in denatured status,and the results show that although both MFE and RCMFE can be used to identify denatured tissues,the intra-class distance of RCMFE on each scale factor is smaller than MFE,and the inter-class distance is larger than MFE.Compared with MFE,RCMFE can calculate the complexity of the signal more accurately and improve the stability,compactness,and separability.When RCMFE is selected as the characteristic parameter,the RCMFE difference between denatured and normal biological tissues is more evident than that of MFE,which helps doctors evaluate the treatment effect more accurately.When the scale factor is selected as 16,the best distinguishing effect can be obtained.     

混合型无穷质点马氏过程的有势性和可逆性

本文考察不超过N个位置同时发生演变的混合型无穷质点马氏过程,证明了这种过程的存在性及测度关于这种过程可逆的判别准则并在一定假设之下给出了有势的充要条件,此时可逆测度集R与Gibbs态集g~N(v)一致,而有势性与可逆性等价。     

Adaptive robust control of chaotic oscillations in power system with excitation limits

With system parameters falling into a certain area, power system with excitation limits experiences complicated chaotic oscillations which threaten the secure and stable operation of power system. In this paper, to control these unwanted chaotic oscillations, a straightforward adaptive chaos controller based on Lyapunov asymptotical stability theory is designed. Since the presented controller does not need to change the controlled system structure and not to use any information of system except the system state variables, the designed controller is simple and desirable. Simulation results show that the proposed control law is very effective. This work is helpful to maintain the power system＇s security operation.[第一段]     

温度对吡啶离子液体性质影响的分子动力学模拟研究

运用分子动力学模拟方法研究了温度对三种吡啶离子液体[BPy][BF_4]、[HPy][BF_4]、[OPy][BF_4]热力学性质的影响,得到了每个体系的密度、自扩散系数、电导率和黏度等.研究结果表明:随着温度升高,同一种离子液体的密度减小,阴阳离子的自扩散系数明显增大,电导率升高,而黏度降低.在同一温度下,随着阳离子上烷基链的增长,离子液体的密度减小,但热力学性质的变化规律并不完全同步.烷基链长最短的[BPy][BF_4]的自扩散系数和电导率在每个温度下均为最大,而黏度最小;但烷基碳链更长的[OPy][BF_4]和[HPy][BF_4]的各种性质相差不大,甚至当温度大于323 K时,烷基链较长的[OPy][BF_4]的自扩散系数比[HPy][BF_4]的大.     

相关免疫逻辑函数的特征矩阵及其计数

本文定义了取值于任意抽象集合的逻辑函数的特征矩阵及其相关免疫性,用概率的方法研究了这类最一般的逻辑函数具有相关免疫性时,其特征矩阵的性质,由此给出了逻辑函数相关免疫的等价判别条件,据此给出了这类相关免疫逻辑函数的一种构造方法并对相关免疫逻辑函数的计数进行了研究,得到了一个一般性的下界.     

具有最高代数次数的2n元n维Bent函数的构造

本文给出了代数次数达到最高的一类布尔置换的代数标准形 ;并用m序列的状态转移矩阵和所得置换 ,构造了一类代数次数达到最高的 2n元n维Bent函数 ,用这类函数所构造的S盒具有较高的安全强度 .     

谈Gumbel分布的均值和方差的计算

<正> 一、引言对概率统计中的极值理论有了解的同志都知道,若随机变量的ξ密度函数是e~(-x)e~((-6)~(-x)) (-∞相似文献   

Controlling chaos in permanent magnet synchronous motor based on finite-time stability theory

This paper reports that the performance of permanent magnet synchronous motor (PMSM) degrades due to chaos when its systemic parameters fall into a certain area. To control the undesirable chaos in PMSM, a nonlinear controller, which is simple and easy to be constructed, is presented to achieve finite-time chaos control based on the finite-time stability theory. Computer simulation results show that the proposed controller is very effective. The obtained results may help to maintain the industrial servo driven system's security operation.     

一类非线性弹性函数的构造

In this paper the decomposition formula of Walsh spectrum of boolean functions is used to construct a class of nonlinear resilient functions.