纳米碳管的电化学贮锂性能

用透射电镜、高分辨透射电镜、X射线衍射和拉曼光谱表征了用催化热解法制备的纳米碳管的结构,研究了纳米碳管的电化学嵌脱锂性能。以纳米级铁粉为催化剂热解乙炔气得到的纳米碳管石墨化程度较低,结构中存在褶皱的石墨层、乱层石墨和微孔等缺陷,具有国交高的贮锂容量,初始容量为640mAh/g,但循环稳定性较差。而以纳米级氧化铁粉为催化剂热解乙烯得到的纳米碳管结构比较规则,循环稳定性较好,但贮锂容量较低,初始容量为282mAh/g。讨论了纳米碳管的结构对其温度特性和不同电流密度下的充放电容易的影响。     

双重Q2重标度模型的重标度参数经验公式

给出了双重Q2 重标度模型的重标度参数经验公式 ,其中建立了重标度参数 ξV,ξS 及 ξG 与原子核平均结合能之间的联系 .利用这套公式可以给出A≥ 1 2的所有核的重标度参数值 ,进而可以采用这些重标度参数值计算有关核过程做出预言 .     

一种新型的圆筒非接触超声马达

提出了一种新型的圆筒非接触超声马达.该马达主要工作在驻波状态下,且仅需单路信号激励。文中给出了马达定子的振动解析,并依此设计定子。当马达稳定转动时,采用激光测振仪测得了马达定子的振动模态。实验表明,单路信号激励下同样可以实现非接触驱动。此外还采用高速摄像机拍摄了马达的起动特性。     

A study on asymmetric coupled waveguides ascompact dispersion compensators

A strong polarization dependence of pulse compression was experimentally observed using an InGaAsP/InP slab-type coupled waveguide structure consisting of two dissimilar waveguides. This polarization dependence strongly demonstrated that the observed pulse compression results from dispersion compensation due to group velocity dispersion (GVD) associated with supermodes. High mode-conversion efficiency over a wide spectral band in mode converters and the possibility of continuous control of supermode GVD by current injection were demonstrated by numerical simulation.     

Virtual Source of a Swallowtail Beam

By applying a virtual source method, the exact and the paraxial solutions of the Swallowtail beams (SBs) that are governed by the inhomogeneous Helmholtz equation are introduced. The paraxial SBs generated experimentally possess both self-accelerating and self-focusing features. The parameters controlling the field distributions are discussed in theory. From the spectral representation of the Swallowtail wave, in the appropriate limit, the first four terms of the nonparaxial correction series for the (1+2)-dimensional Swallowtail waves that simplify to the SBs are obtained.     

Electronic structure of F,-center in MgO

The embedded-cluster numerical variational method has been developed to calculate the electronic structure of perfect MgO, F and F⁺-centers in MgO. The energy band, bulk density of states has been calculated by cluster Mg₁₄O₁₃, Mg₁₄O₁₂F⁺ and Mg₁₄O₁₂F. The calculated absorption energy for F⁺ and F centers is in good agreement with experimental data. In our calculated defect energy levels, that the first excited state of F⁺-center is at CB-3.46 eV, indicates the necessity of a large photoelectron yielding energy. We also calculate the radius of color center electron, and plot the map of charge-density distribution of valence electrons in which the structure of the color center is shown directly. Received 22 May 1998     

La0.5Ca0.5-xBaxMnO3体系中的异常磁电阻行为

实验研究了La0.5Ca0.5MnO3系统Ca位上Ba掺杂对其磁电阻效应的影响.结果表明,掺杂量低于0.2的样品,磁电阻效应随温度降低而增大,在转变温度附近达到最大值,然后随温度降低而变小,随着温度进一步降低磁电阻效应再次增大.而对于掺杂量高于0.2的样品,磁电阻效应在整个温区随温度降低而单调增加.文中通过考虑铁磁性和反铁磁性两种效应的竞争而对实验观察给出解释.     

电感耦合等离子体原子发射光谱分析中光谱干扰校正卡尔曼滤波法研究

本文利用电感耦合等离子体原子发射光谱多色仪的扫描功能,用卡尔曼滤波法对各种光谱干扰进行校正。结果表明,该法能处理各种类型光谱干扰,不需要样品基体匹配,其测定回收率明显优于在峰法和离峰法,具有简便、准确等优点。     

NAB和NYAB晶体的斯塔克能级

在液氮温度下测量ＮＡＢ和ＮＹＡＢ的全波段吸收光谱，并由此初步指认了ＮＡＢ和ＮＹＡＢ的斯塔克能级，利用Ｊ－Ｒ理论首次对ＮＡＢ和ＮＹＡＢ的斯塔克能级进行了全谱项拟合计算，并作了正确的指认。     

一种多重图像融合系统的电配准技术

在多光谱实时图像融合实验系统的基础上,提出一种实现图像融合系统中非共轴光学系统微小量配准的电子学方法,讨论了配准原理、所采用的技术方案及系统实现的技术途径。在机械粗配准之后,系统可快速实现系统微小量的配准功能