Impulsive synchronization of time delay bursting neuron systems with unidirectional coupling

In the article, impulsive synchronization of chaotic bursting in Hindmarsh–Rose neuron systems with time delay via partial state signal is investigated. Based on impulsive control theory of dynamical systems, the sufficient conditions on feedback strength and impulsive interval are established to guarantee the synchronization. Numerical simulations show the effectiveness of the proposed scheme. The obtained results may be helpful to understand dynamical mechanism of signal transduction in real neuronal activity. © 2014 Wiley Periodicals, Inc. Complexity 21: 38–46, 2015     

矩阵的广义特征值及特征向量的神经网络方法

矩阵特征值及特征向量计算在实际问题中有广泛的应用.应用神经网络方法来计算广义特征值及对应的特征向量,给出了相应的算法,并对给出的算法在数学上进行了严格证明.并用实例验证了其正确性.     

Panel‐based stratified cluster sampling and analysis for photovoltaic outdoor measurements

We study a stratified multisite cluster‐sampling panel time series approach in order to analyse and evaluate the quality and reliability of produced items, motivated by the problem to sample and analyse multisite outdoor measurements from photovoltaic systems. The specific stratified sampling in spatial clusters reduces sampling costs and allows for heterogeneity as well as for the analysis of spatial correlations due to defects and damages that tend to occur in clusters. The analysis is based on weighted least squares using data‐dependent weights. We show that this does not affect consistency and asymptotic normality of the least squares estimator under the proposed sampling design under general conditions. The estimation of the relevant variance–covariance matrices is discussed in detail for various models including nested designs and random effects. The strata corresponding to damages or manufacturers are modelled via a quality feature by means of a threshold approach. The analysis of outdoor electroluminescence images shows that spatial correlations and local clusters may arise in such photovoltaic data. Further, relevant statistics such as the mean pixel intensity cannot be assumed to follow a Gaussian law. We investigate the proposed inferential tools in detail by simulations in order to assess the influence of spatial cluster correlations and serial correlations on the test's size and power. ©2016 The Authors. Applied Stochastic Models in Business and Industry published by John Wiley & Sons, Ltd.     

Early transient responses of multi-span stepped single-walled carbon nanotubes using the method of reverberation ray matrix

The early transient responses of multi-span stepped single walled carbon nanotubes (SWCNTs) under impact loadings are studied by the method of reverberation ray matrix (MRRM). The dynamics model of the carbon nanotubes is established in the Fourier phase space on the basis of the nonlocal Timoshenko beam model. The wave solutions of SWCNTs with arbitrary boundary conditions are obtained by the wave method. The reverberation ray matrix of the multi-span stepped SWCNTs is the product of scattering, phase and permutation matrices, which can be determined by the impact loadings, continuous conditions and boundary conditions. The early transient responses can be calculated by the inverse Fourier transform of the sum of initial ray groups. It can be found that the early transient displacement response in the very short time subjected to the impact loading is very small, while the transient transverse shear strain becomes large in the very short time. The influences of nanotubes span number, nanotubes type and boundary conditions on the early transient responses of multi-span stepped SWCNTs are investigated.     

噪声环境下语音信号的基音检测

研究和改进了一种基于归一化互相关系数的基音检测方法(NCCFPDA)。NCCFPDA算法利用归一化互相关系数、短时归一化能量和自适应门限来区分清/浊音和选取基音周期,计算量小,精度高。在NCCFPDA算法的基础上,采用动态规划的方法对检测出的基音周期进行平滑,并在噪声环境下与自相关法检测基音周期的检测结果进行了比较。实验表明NCCFPDA算法在基音轨迹的平滑和清/浊判别方面都具有令人满意的效果,能实现基音周期的鲁棒性检测。     

简单电力系统中波过程收敛性分析

在分析电力系统时,传统的处理方法是如果输电线路的电磁暂态已经结束,就仅考虑机电暂态过程.本文以负荷节点电压代表系统状态,利用解析法分析了一个简单系统在不同情况下电磁暂态过程,得到了以节点瞬时电压代表的系统状态随时间变化的表达式,比较了不同情况下系统状态的变化过程,证明了传统的处理方法只是在一般情况下适用.而在特殊情况下,必须考虑输电线路的电磁暂态和这一过程中系统状态的变化规律.     

房间环境下基于四阶累积量的语音时延估计

主要研究了利用四阶累积量在房间环境下的语音信号时延估计。根据模拟实验环境和实际实验环境下的仿真结果,分别比较了在高斯白噪声情况下与有色高斯噪声情况下基于二阶统计量的广义互相关法和基于四阶累积量的时延估计法性能,验证了四阶累积量法的有效性。仿真结果表明四阶累积量法具有很好的鲁棒性。     

晶体管混频器混频增益的简化计算

本文介绍一种方法简单、便于学生理解的分析晶体管混频器混频增益的简化计算方法.该方法从晶体管的电流方程入手,通过分析晶体管混频器的混频原理,得到了输出中频电流和混频跨导、混频增益的简明数学表示.通过对典型混频器电路的仿真,验证了该方法的有效性.该方法与传统的时变偏置电压分析方法相比,混频跨导和混频增益容易求得,解决了以往混频跨导基本是一个概念参数而难以确定具体数值的问题.     

低相干光干涉法延时测量中的误差分析

低相干光干涉法通过测量宽谱光通过待测器件之后的相位变化得到其相对延时量。采集宽谱光时域干涉数据,利用傅里叶变换提取出频域相位信息后再进行相位展开、多项式拟合处理,所得相位曲线对频率求导可得待测延时曲线。延时测量误差来源于干涉信号强度误差和纯相位误差。理论分析和仿真计算表明,延时误差与相位误差成正比;强度噪声引起的相位误差与噪声强度成正比,且该类噪声可通过曲线拟合算法得到有效抑制。实验表明,温度等环境因素引起的纯相位误差是延时测量误差的主要因素。实验上,对约19 m光子晶体光纤于1540~1560 nm波段的相对延时进行了测量,达到了0.14 ps的精度。     

Photoinduced Proton Transfer between Photoacid and pH‐Sensitive Dyes: Influence Factors and Application for Visible‐Light‐Responsive Rewritable Paper

Ink‐free printing based on rewritable paper is an efficient and environmental friendly way to reuse paper, protect resources, and save energy for sustainable development of human society. Among various kinds of rewritable media, light responsive rewritable paper (LRP) is one of the most popular research areas due to its clean and favorable noncontact writing. Visible light is more suitable for LRP for its superior penetration and much less damages to organic molecules than UV light. However, visible‐light‐responsive rewritable paper (VLRP) has only limited successes so far. Herein, a VLRP is newly designed and fabricated based on photoinduced proton transfer (PPT) between photoacid and pH‐sensitive dyes. Success of it is highly benefited from systematical investigation and in‐depth understanding on the key influence factors, such as concentration‐induced undesired isomerization, temperature, humidity, and light intensity, on the PPT and its inverse process. As‐prepared VLRP shows long‐awaited properties, such as, high color contrast and resolution, appropriate legible time of prints, excellent reversibility (>100 cycles), easiness to achieve multicolor prints, and agreeing well with environmental concept of green printing. In addition, study of influence factors on PPT in this work, to some extent, may also help people understand complex photocycle process in biosystem.