Duffing系统的欧拉实现方法研究

在研究Duffing系统的基础上,为了利用Duffing系统进行弱信号检测,必须实现一种可靠的Duffing系统模型。对3种基于欧拉方程的模型实现方式进行了对比,通过分析欧拉方程的几何意义,并结合DSP Builder的特点,提出了一种易于工程实现的改进欧拉形式。通过对四种算法进行仿真实验得出,运用不同的状态模型建立Duffing系统会改变振子相变的临界策动力幅值,但不会对系统固有存在的状态产生影响。     

Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

The structural and chemical stabilities of immobilized polyoxometalate (POM)‐containing catalysts are crucial factors for their industrial application. An alumina supported POM catalyst is prepared by using a facile condensation reaction between the trilacunary POM Na₁₂[α‐P₂W₁₅O₅₆] ? 24 H₂O (P₂W₁₅) and the hydroxy groups on the surface of γ‐Al₂O₃ spheres under acidic conditions. The heterogeneous catalyst P₂W₁₅?Al₂O₃ is characterized by a wide variety of techniques and shows excellent stability and highly efficient reactivity and selectivity for the oxygenation of thioethers to sulfoxides, which are a very useful intermediate in organic synthesis and the industrial preparation of drugs. Furthermore, P₂W₁₅?Al₂O₃ can be recycled and reused at least ten times without any observable loss of its catalytic efficiency, mainly due to the covalent immobilization and high dispersion of P₂W₁₅ on the γ‐Al₂O₃ surface.     

工业以太网网络流量的特性分析与建模研究

针对一个特定工业以太网系统提出了一种有效的网络流量建模思路.首先选取系统中一条流量最大的关键链路作为研究对象,采用wireshark软件捕获流经该链路的不同协议数据包,并根据数据包大小和到达时间计算得出每种协议的流量.然后分别对其中主体协议(CIP协议和TCP协议)的流量进行时频特性和小波特性分析,发现CIP协议具有平稳的周期性,而TCP协议则体现出明显的趋势特性;针对这两种协议的不同特性,提出采用SVR模型对网络流量进行建模,利用Matlab中的libsvm工具箱进行仿真分析,结果表明了算法的有效性.     

基于Monte Carlo采样的压缩感知弱匹配去噪重构

最小二乘是现有贪婪迭代类压缩感知重构算法中通用的信号估计方法,其未考虑到可能将量测噪声引入信号估计的情况.针对以上不足,提出一种基于Monte Carlo采样的压缩感知弱匹配去噪重构算法.该算法在未知信号稀疏度先验的条件下,通过引入递推Bayesian估计减小量测噪声的干扰;同时,以弱匹配的方式筛选出有效的原子,并剔除冗余原子进而重构原信号.新算法继承了现有贪婪迭代类算法的有效性,同时避免了因噪声干扰或稀疏度未知导致的重构失败.理论分析和实验表明,新算法在同等条件,尤其是非高斯噪声情况下,重构性能优于现有典型贪婪迭代类算法,且其运算时间低于BPDN算法和同类的KF-SAMP算法.     

Determination of critical micelle concentrations and aggregation numbers by fluorescence correlation spectroscopy: aggregation of a lipopolysaccharide

Fluorescence correlation spectroscopy (FCS) is often used to determine the mass or radius of a particle by using the dependence of the diffusion coefficient on the mass and shape. In this article we discuss how the particle size of aggregates can be measured by using the concentration dependence of the amplitude of the autocorrelation function (ACF) instead of the temporal decay. We titrate a solution of aggregates or micelles with a fluorescent label that possesses a high affinity for these structures and measure the changes in the amplitude of the ACF. We develop the theory describing the change of the ACF amplitude with increasing concentrations of labels and use it to fit experimental data. It is shown how this method can determine the aggregation number and critical micelle concentration of a standard detergent nonaethylene glycol monododecyl ether (C₁₂E₉) and a lipopolysaccharide (LPS: Escherichia coli 0111:B4).     

复合形法在PDP计算机仿真中的应用

采用复合形算法建立数学模型,以PDP三维模拟仿真软件为基础,以PDP放电效率为目标函数,以扫描电极宽度、氙气比例、气体压强和驱动电压为搜索变量,进行最优化设计来提高单元的放电效率.模拟结果表明:搜索变量坐标为(80,15,498,230)时,即扫描电极宽度、氙气比例、气体压强及维持电压分别为80 μm、15%、6.6×104Pa和230 V时,对应的放电效率取得最大值11.0%,比搜索变量坐标为(160,5,310,210)初始复合形时的放电效率提高一倍多,且真空紫外辐射能量也比初始复合形时增加79%.模拟结果表明采用复合形算法可以得出影响PDP放电性能的各因素的最优化组合,使PDP单元的放电效率和放电强度都大幅提高.     

变换域通信系统基函数生成方法改进

变换域通信系统通过信道估计在变换域设计信号波形避开干扰,它没有采用载波调制,而是用一个类似噪声的基函数进行信息调制.通过引入干扰系数丰富了基函数的频谱结构,提高了基函数的自正交性,使基函数更适合正交调制,增强了变换域通信系统的抗干扰能力.特别是在干扰信号较强的情况下,能够保证系统的信息传输畅通.通过仿真比较改进前后基函数的自相关性,验证了前面的理论.     

Intuitionistic uncertain linguistic powered einstein aggregation operators and their application to multi-attribute group decision making

The intuitionistic uncertain fuzzy linguistic variable can easily expressthe fuzzy information, and the power average (PA) operator is a usefultool which provides more versatility in the information aggregation procedure.At the same time, Einstein operations are a kind of various t-normsand t-conorms families which can be used to perform the corresponding intersectionsand unions of intuitionistic fuzzy sets (IFSs). In this paper, wewill combine the PA operator and Einstein operations to intuitionistic uncertainlinguistic environment, and propose some new PA operators. Firstly,the definition and some basic operations of intuitionistic uncertain linguisticnumber (IULN), power aggregation (PA) operator and Einstein operationsare introduced. Then, we propose intuitionistic uncertain linguistic fuzzypowered Einstein averaging (IULFPEA) operator, intuitionistic uncertain linguisticfuzzy powered Einstein weighted (IULFPEWA) operator, intuitionisticuncertain linguistic fuzzy Einstein geometric (IULFPEG) operator and intuitionisticuncertain linguistic fuzzy Einstein weighted geometric (IULFPEWG)operator, and discuss some properties of them in detail. Furthermore, we developthe decision making methods for multi-attribute group decision making(MAGDM) problems with intuitionistic uncertain linguistic information andgive the detail decision steps. At last, an illustrate example is given to showthe process of decision making and the effectiveness of the proposed method.     

Ultrafast dephasing of interband transitions in semiconductors

Two basic types of dephasing mechanisms, carrier-carrier and carrier-phonon scattering including hole-hole and hole-phonon scattering are proposed in the theory of ultrafast polarization dephasing of continuum transitions in bulk semiconductors. The contribution of optical phonon scattering to the dephasing rate is the average of the scattering rates for electrons and holes. A weighting factor that reflects the change in the momentum of the particle in a collision is introduced into the usual integral of the carrier-carrier scattering rate to describe the contribution of carrier-carrier scattering to the dephasing rate for the case of static screening interaction. The theoretical calculations are in quantitative agreement with the reported experimental results.