一类二元相关威布尔分布的可靠性问题

本文考虑生存函数为${\ol{F}(x_{1},x_{2})}=\exp\{-[(x_{1}^{1/\alpha}/\theta_{1})^{1/\delta}+(x_{2}^{1/\alpha}/\theta_{2})^{1/\delta}]^{\delta}\},\;x_{i}>0,\;\alpha>0$, $1\geq\delta>0,\;\theta_{i}>0\;(i=1,2)$的二元威布尔分布的两种可靠性问题, 提出可靠度$\pr$的估计并讨论了它们的渐近性, 最后还作了模拟计算.     

实证研究中预测模型的选择:从逐步回归到信息标准

本文首先对显著性变量同变量显著性之间的关系予以讨论并区分,进而评价逐步回归模型选择法的缺陷性。在此基础上,我们对以AIC和B IC为代表的各种基于信息标准的模型选择法予以介绍和评论。同逐步回归法相比,信息标准模型选择法有着坚实的统计理论基础及清晰而优良的统计性质。本文通过基于近十年中国股市数据的实证检验说明,信息标准同逐步回归相比往往能产生具有更强预测能力的计量模型,因此值得在未来的实证研究中注意并推广。     

ALICE实验中光子谱仪的触发选判机制的模拟研究

对ALICE实验光子谱仪的触发选判机制进行了模拟研究, 内容包括: 1) 对光子谱仪的能量重建性能进行了研究, 通过计算机模拟检验光子谱仪探测器对大横动量范围的入射粒子的能量重建性能; 2) 对光子谱仪探测器的事件触发效率进行了研究, 通过计算机模拟分析触发阈值的选取并计算触发效率; 3) 对光子谱仪探测器的事件触发频率进行了研究, 通过计算机模拟对p-p和Pb-Pb两种碰撞模式下的触发频率分别进行了估算和讨论.     

Relativistic Electromagnetic Solitary Wave in a Cylindrical Magnetized Plasma

In the presence of an applied static and uniform magnetic field, a cylindrical Kadomtsev-Petviashivili equation is derived for a relativistic electromagnetic solitary wave propagating in collisionless plasma consisting electrons, positrons, and ions in the case of weak relativistic limit. This equation is solved in a stationary frame to obtain explicit expression for the velocity, amplitude and width of solitons. The amplitude of the solitary wave has a maximum value at a critical αc of the ratio of the ion equilibrium density to the electron one, and it increases as the applied magnetic field becomes larger.     

Measurements of AIM for Visible Wavelength Based on Individual Eye Model

We measure and calculate the aerial image modulation （AIM） of human retina for visible wavelengths based on the individual eye model. By employing the optical design software ZEMAX, we obtain the modulation transfer function （MTF） of human eye in visible wavelengths. Using CSV-1000 and VAF-1000, the contrast sensitivity function （CSF） and the visual acuity （VA） for the same eye are measured. Then the AIM of human retina could be acquired by the relations between MTF and CSF and between MTF and VA. The AIM of human retina is independent of MTF, and the values of AIM for normal eyes （without retina disease） are similar, so the assembly average for large numbers of normal eyes can be a standard AIM curve, which is helpful for the diagnosis of diseases in the retina system.     

Effect of Nonradiative Recombination on Carrier Dynamics in GaInNAs/GaAs Quantum Wells

The nonradiative recombination effect on carrier dynamics in GalnNAs/GaAs quantum wells is studied by timeresolved photoluminescence （TRPL） and polarization-dependent TRPL at various excitation intensities. It is found that both recombination dynamics and spin relaxation dynamics strongly depend on the excitation intensity. Under moderate excitation intensities the PL decay curves exhibit unusual non-exponential behaviour. This result is well simulated by a rate equation involving both the radiative and non-radiative recombinations via the introduction of a new parameter of the effective concentration of nonradiative recombination centres in the rate equation. In the spin dynamics study, the spin relaxation also shows strong excitation power dependence. Under the high excitation power an increase of spin polarization degree with time is observed. This new finding provides a useful hint that the spin process can be controlled by excitation power in GaInNAs systems.     

Thermal desorption of interacting molecules from mixed adlayers

A Monte Carlo simulation method is used to study thermal desorption of gas molecules from mixed adlayers containing two species. The effects of lateral interactions among adatoms and initial surface coverage on the desorption spectra are examined. It is shown that attractive lateral interactions lead to sharper peaks and that desorption occurs at high temperatures, whereas repulsive interactions lead to multiple peak spectra. It is found that interactions between unlike molecules affect the spectra for species with lower desorption energy only, and that the two species desorb together only in certain cases. Lateral interactions also affect the desorption kinetics significantly and very different behavior for the two species may be obtained.     

q变形对相干态的相位概率分布特性

通过推广Pegg和Barnett的相位算符和相位态到q变形的双模情况, 应用数值计算 研究了q变形对相干态的相位概率分布特性. 结果表明, q变形对相干态的相位概率分布受到相位参数、q参数和参数│ξ│的调节, 从而反映出不同的量子相干特性.     

Single Qubit and Its Universal Logic Gate Made of a Heisenberg Spin Cluster with Five Particles

We investigate an anisotropic Heisenberg spin cluster with five particles controlled by a time-dependent magnetic field. With the algebraic dynamical method, we obtain the exact analytical solution to the time dependent Schr6dinger equation. Based on the analytical solution, it is shown that the system can be used as a universal single qubit logic gate controlled by the strength and frequency of the magnetic field, and the six special single qubit logic gates can be realized physically. We also discuss the anti-decoherence property of the qubit and its logic gates resulted from particle coupling effect and collectivity of the cluster.     

The promoting role of silver on the supported silver salt of dodecatungstosiliticic acid in the methanol-to-hydrocarbon conversion

The conversion of methanol into light olefins has been studied using the silver salt of dodecatungstosilicic acid supported on serosil. Special attention has been paid to the process of the acid sites formation during the initial reaction period and to the role of hydrogen. The significantly higher activity and stability of the supported silver salt compared with the supported free heteropoly acid is explained by a controlled formation process of acidic sites and their additional generation from hydrogen on the metallic silver surface.