相位型宽频带激光测振仪的研究

在理论上详细描述了一种新型的激光偏振移相干涉测振系统.通过计算机对两路正交干涉光电信号的接收和正弦逼近法数字处理,在1Hz～10KHz宽频带内测量振动台的振幅和初相位,从而实现加速度传感器复合灵敏度的绝对校准.运用琼斯矩阵证明干涉系统中通过偏振片调整可保证两信号的正交性.     

Dual problems for weak and quasi approximation properties

It is shown that for the separable dual X^∗ of a Banach space X if X^∗ has the weak approximation property, then X has the metric quasi approximation property. Using this it is shown that for the separable dual X^∗ of a Banach space X the quasi approximation property and metric quasi approximation property are inherited from X^∗ to X and for a separable and reflexive Banach space X, X having the weak approximation property, bounded weak approximation property, quasi approximation property, metric weak approximation property, and metric quasi approximation property are equivalent. Also it is shown that the weak approximation property, bounded weak approximation property, and quasi approximation property are not inherited from a Banach space X to X^∗.     

Scattering by large bubbles: Comparisons between geometrical-optics theory and Debye series

The scattering patterns and optical properties of large spherical bubbles in water are calculated by both Geometrical-optics theory and Debye-series expansion of the Mie amplitudes. In the Geometrical-optics calculations, the wave-front spreading factor and phase information are all taken into consideration. A detailed comparison between the two methods is presented. It is found that scattering patterns calculated from the Geometrical-optics approach agree reasonably with those obtained by Debye series when the size parameter is larger than approximately 400. In the case of scattering properties, the Geometrical-optics method can produce reliable results with the Debye expansion for size parameters larger than approximately 50. The Geometrical-optics results without the phase interferences are also reliable, but it cannot display the oscillations and the ripple structure as a function of size parameter.     

电磁场中空间思维的构建

利用电子线路实验实现了用变量脉冲扰动法控制离散混沌 .该方法只用单一输出信号作为反馈信号 ,每隔一定的脉冲间隔将其加到系统的某些变量中去 ,适当调节脉冲间隔和反馈系数 ,可得到多个稳定的周期轨道 .该方法不仅适用于一维和二维离散系统 ,也适用于三维或更高维的离散系统 .     

Molecular dynamics study on the field effect ion transport in carbon nanotube

We investigated potassium ion transport in the (5, 5) carbon nanotube by using classical molecular dynamics simulations under applying external force fields. This can be applied to nanoscale ionic-field-effect devices. As the applying external force field increases, the potassium ions rapidly go through the nanochannel. Under the low external force fields, the thermal fluctuation of the nanochannel affected on the tunneling of the potassium ions, whereas the effects of the thermal fluctuation were negligible under the high external force fields.     

STM and AFM observations of damage produced by swift Ne and Kr ions in graphite

Radiation damage of highly oriented pyrolitic graphite (HOPG) samples have been investigated following irradiation with 215 MeV Ne and 209 MeV Kr ions, available at U-400 cyclotron, Dubna. A freshly cleaved HOPG surface was irradiated perpendicularly to the sample surface (c plane). A low ion irradiation dose was used (10¹² ions/cm²) in order to avoid damage overlap. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are useful methods allowing direct observation of surface defects. The observations were made after irradiation without any further sample preparation. The experimental results are compared to computer simulations (TRIM code) and primary knonked-on atomic spectrum calculations (LET code). Clear distinction can be made between surface features attributed to nuclear stopping effects and defects owing to electronic stopping mechanisms.     

Calculation of interband magneto-optical transition linewidth in Ge by combined projection technique

Using a combined projection technique, we calculate the line-shape function for the magneto-optical direct interband transition in an electron-phonon system. From the plot of the absorption power vs the frequency of the electro-magnetic wave, we obtain the linewidth in Ge at 300 K, where only the deformation potential phonon scattering is taken into account. The obtained value (1.7 meV) is compared with the experimental value (2.0 meV) of Burstein et al. [11].     

Virtual topology design of shared channel lightwave networks

Channel sharing in a WDM-based lightwaue network provides a way to reduce the number of wauelengths required for the implementation of a large network, while the network virtual connectivity can be dramatically increased. In this paper, we first introduce a so-called group policy that achieves a virtual topology with maximum connectivity and simplifies the optimal design of a trafjic sensitiue virtual topology. We propose a two-stage algorithm: a node-to-group assignment and a wauelength-to-group assignment. The results show that the proposed algorithm is a practical tool that efjiciently reconfigures the connectivity diagram to fit best the current traffic pattern.     

托卡马克等离子体LHCD与ECCD的协同作用

本文通过求解Fokker-Planck方程和射线追踪技术,详细研究了托卡马克等离子体中,低混杂波电流驱动(LHCD)与电子回旋波电流驱动(ECCD)的协同作用,结果表明,这种协同作用有利于用EC波驱动电流;捕获电子效应对电流驱动有一定影响,特别是O波弱场注入时,影响更为明显;驱动的电流对平衡磁场很敏感,磁场的大小也影响驱动电流的剖面。     

Simplification and accuracy test for the collision cross-section-based quantification of isomeric ion mixtures

A method was devised to determine the isomeric composition of an ionic mixture using collisionally activated decomposition mass spectrometry. Compared with the more rigorous approach based on collision cross-sections reported previously, the main advantage of the proposed method is its experimental simplicity. Both the internal consistency and the accuracy of the method were tested for mixtures of isobaric ions, i.e. ions with the same nominal mass-to-charge ratios.