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本文研究了独立随机变量之和的绝对矩的几个性质, 其中包括$\ep|X+Y|-\ep|X-Y|$的表达式, 这里$X$和$Y$是相互独立的随机变量.     

Multiple periodic solutions of a delayed stage-structured predator–prey model with non-monotone functional responses

A delayed stage-structured predator–prey model with non-monotone functional responses is proposed. It is assumed that immature individuals and mature individuals of the predator are divided by a fixed age, and that immature predators do not have the ability to attack prey. Some new and interesting sufficient conditions are obtained for the global existence of multiple positive periodic solutions of the stage-structured predator–prey model. Our method is based on Mawhin’s coincidence degree and novel estimation techniques for the a priori bounds of unknown solutions to Lx = λNx. An example is given to illustrate the feasibility of our main result.     

SILEX-1装置上等离子体尾场加速电子初步实验

激光等离子体加速电子机制可以产生准单能的高能电子束, 近年来成为国际上的研究热点. 中国工程物理研究院激光装置已经能够达到286TW的输出功率, 为国内在该领域的研究提供了实验条件. 文章介绍了在SILEX-1装置上开展的激光等离子体加速电子的初步实验, 并对测得结果进行讨论, 为下一步实验的进行提供了准备条件.     

Feature Selection using Fuzzy Support Vector Machines

The feature selection consists of obtaining a subset of these features to optimally realize the task without the irrelevant ones. Since it can provide faster and cost-effective learning machines and also improve the prediction performance of the predictors, it is a crucial step in machine learning. The feature selection methods using support machines have obtained satisfactory results, but the noises and outliers often reduce the performance. In this paper, we propose a feature selection approach using fuzzy support vector machines and compare it with the previous work, the results of experiments on the UCI data sets show that feature selection using fuzzy SVM obtains better results than using SVM.     

一种跳频扩时码的构造及性能分析

以一维二次同余码(QCC)作为扩时模式，以光正交码(OOC)和QCC码作为频域跳频模式，通过时域和频域的组合，构造了适用于光码分多址(OCDMA)系统的QCC/QCC和QCC/OOC 2种跳频扩时码，并对码的容量及其相关性进行了分析。与一维QCC码相比，QCC/QCC跳频扩时码的容量扩大了p 1倍（p为码重），相关性得到改善，并且码字异相自相关限λa=1，互相关限λc=2；QCC/OOC跳频扩时码具有更大的码容量和更好的相关性，码字异相自相关限λa=0，所有码字按一定规律可分成p 1组（p为码重），每组内码字的互相关限λa=1，不同组间码字的互相关限λa=2。所得结果为光码分多址系统中跳频扩时码的构造提供了一种新的方法。     

自组装双硫醇分子膜阻抗谱的研究

对交流电场下双巯基烷烃硫醇自组装分子膜的阻抗谱进行了研究.利用汞金属作为衬底,制备出双巯基烷烃硫醇自组装分子膜,并通过交流频谱仪对其进行频谱的扫描．明确了膜的作用范围为阻抗谱中频部分为了解释该阻抗谱,提出了一种串联的等效电路来进行了拟合,并与其他的模型进行比较.同时,观察到在损耗谱中损耗峰随硫醇碳链原子数的增加而向低频方向移动并得出双巯基硫醇(C6-C10)在交流电场下的激活能为23～39 meV．     

彩色透明微晶玻璃的吸收光谱

在Li2O-Al2O3-SiO2系统玻璃中掺入少量晶核剂TiO2,ZrO2,P2O5，再掺入稀土离子和过渡金属离子作为着色剂，在高温下溶制得到彩色透明玻璃，对上述玻璃进行微晶化处理，用差热分析（DTA）确定其晶化温度，测定与讨论了所获彩色透明微晶玻璃在紫外波段至近红外波段的吸收光谱特性，研究结果表明，玻璃微晶化后，由于基质玻璃对光的微弱散射，引起吸收的增强，但不改变稀土离子和过渡金属离子的本征吸收峰位。     

A New theory for evaluating the number density of inclusions in films

A new formulation derived from thermal characters of inclusions and host films for estimating laser induced damage threshold has been deduced. This formulation is applicable for dielectric films when they are irradiated by laser beam with pulse width longer than tens picoseconds. This formulation can interpret the relationship between pulse-width and damage threshold energy density of laser pulse obtained experimentally. Using this formulation, we can analyze which kind of inclusion is the most harmful inclusion. Combining it with fractal distribution of inclusions, we have obtained an equation which describes relationship between number density of inclusions and damage probability. Using this equation, according to damage probability and corresponding laser energy density, we can evaluate the number density and distribution in size dimension of the most harmful inclusions.     

Autocorrelation Function of Hydrogen Atoms in Magnetic Fields

The autocorrelation function is an important quantity that can reflect the dynamical properties of the Rydberg wave packet and can be measured in experiments. Applying time-dependent perturbation theory and rotating wave approximation, we derive the autocorrelation function of the double-pulse laser describing the evolution of a Rydberg wave packet of hydrogen atoms in magnetic fields. The resulting expression is written as a sum of the modified Caussian terms. Each Caussian term comes from a parent semiclassical closed orbit. It provides a direct explanation and experimentally controllable measurement scheme, which allows us therefore to recognize the closed orbit and to determine its returning time in high precision.     

Moderate and Small Deviations for the Ranges of One-Dimensional Random Walks

We establish moderate and small deviations for the ranges of integer valued random walks. Our theorems apply to the limsup and the liminf laws of the iterated logarithm. We establish moderate and small deviations for the ranges of integer valued random walks. Our theorems apply to the limsup and the liminf laws of the iterated logarithm.