冲击载荷下饱和砂土中孔隙水压力的变化及其与液化密实的关系

介绍了实验装置与测压系统，实测了饱和砂柱自由落体撞击地面后前期快过程和后期慢过程的水压力的变化。

Dynamic stress intensity factor of a functionally graded material under antiplane shear loading

The dynamic response of a finite crack in an unbounded Functionally Graded Material (FGM) subjected to an antiplane shear loading is studied in this paper. The variation of the shear modulus of the functionally graded material is modeled by a quadratic increase along the direction perpendicular to the crack surface. The dynamic stress intensity factor is extracted from the asymptotic expansion of the stresses around the crack tip in the Laplace transform plane and obtained in the time domain by a numerical Laplace inversion technique. The influence of graded material property on the dynamic intensity factor is investigated. It is observed that the magnitude of dynamic stress intensity factor for a finite crack in such a functionally graded material is less than in the homogeneous material with a property identical to that of the FGM crack plane.

用赝势方法计算五种简单金属的Hugoniot曲线

基于本文作者在文献[1]中所导出的冷压P_x,利用德拜固体模型并考虑电子的热压,得到了金属的高温高压状态方程。在与Hugoniot方程联立后,就能算出Hugoniot曲线。本文计算了五种简单金属的Hugoniot曲线。结果表明,在现有实验数据所能达到的范围内,理论计算与实验符合都比较好。

低能离子束沉积制备GaAs:Gd的研究

对室温条件下用低能离子束沉积得到的 Ga As∶ Gd样品 ,借助 X射线衍射 (XRD)和高分辨 X射线衍射 (HR-XRD)进行了结构分析 ,结果表明没有出现新的衍射峰 ,并且摇摆曲线的形状与 Gd的注入计量密切相关 .运用 X光电子能谱仪对比分析了 Gd注入后 ,衬底中主要元素 Ga2 p和 As3d的化学位移 ,以及不同计量的样品中注入的Gd4 d芯能级束缚能的变化 ,并分析了铁磁性产生的可能原因 .

一种硅微机械谐振器的单光源激振测振方法

提出一种用于硅微机械谐振传感器研究的单光源激振测振新方法，即微谐振器的激励及其谐振信号的测量使用同一光源。该方法采用全光纤斐索干涉仪结构，将干涉信号与光源强度变化信号进行运算后，通过选频技术解调出谐振器的振动信息，同时采用贝塞耳函数比值法扩大了振动幅度的测量范围，省去了一些难以获得准确数值的工作参数的计算。采用该方法实现了微悬臂梁结构形式的谐振器件的单光源激振与测振，获得了器件的谐振频率约为8．81kHz以及谐振状态下的振动幅度约为135nm。实验结果与采用其他双光源激振测振方法基本一致，新方法的可行性得

The origin of the super-resolution via a nonlinear thin film

In laser applications, resolutions beyond the diffraction limit can be obtained with a thin film of strong optical nonlinear effect. The optical index of the silicon thin film is modified with the incident laser beam as a function of the local field intensity n(r) similar to E-2(r). For ultrathin films of thickness d << lambda the transmitted light through the film forms a profile of annular rings. Therefore, the device can be related to the realization of super-resolution with annular pupils. Theoretical analysis shows that the focused light spot appears significantly reduced in comparison with the diffraction limit that is determined by the laser wavelength and the numerical aperture of the converging lens. Analysis on the additional optical transfer function due to the thin film confirms that the resolving power is improved in the high spatial frequency region. (C) 2007 Published by Elsevier B.V.

大模场面积光纤激光器拉锥法模式选择

大模场面积(LMA)光纤激光器的光束质量通常比单模光纤激光器的光束质量差。采用光纤拉锥的方法进行模式选择,从而提高大模场直径光纤激光器的光束质量。拉锥区距光纤激光器的输出端约5 mm,纤芯最小为9 μm,约为未拉锥部分纤芯直径26 μm的1/3。实验研究表明,在拉锥后,光纤激光器的光束质量因子M2由3.50减小为1.81,相应的斜率效率由63.6%减小为51.1%。虽然拉锥后最大输出功率减少了约19.8%,但其亮度增大为拉锥前的3倍。

Bismuth-activated luminescent materials for broadband optical amplifier in WDM system

New broadband near infrared luminescence covering the whole work windows (1260-1625 nm) of the current wavelength division multiplexing (WDM) system was found from bismuth-activated M2O-Al2O3-SiO2 (M = Li, Na) and Li2O-Ta2O5-SiO2 glasses at room temperature in the case of 808 nm-laser excitation. But the near infrared luminescence mechanism of the bismuth-activated glasses is not well understood up to now. The figure-of-merits of bandwidth and gain of the glasses are better than those of Er3+-doped silicate glasses and Ti3+ doped sapphire, implying they are the promising gain-medium candidates for the broadband amplifiers and the widely tunable laser sources. (c) 2007 Elsevier B.V. All rights reserved.

Superbroadband 1310 nm emission from bismuth and tantalum codoped germanium oxide glasses

Near-infrared broadband emission from bismuth-tantalum-codoped germanium oxide glasses was observed at room temperature when the glasses were pumped by an 808 nm laser diode. The emission band covered the 0, E, S, C, and L bands (1260-1625 nm), with a maximum peak at similar to 1310 nm, a FWHM broader than 400 nm, and a lifetime longer than 200 lis. The observed broadband luminescence was attributed to bismuth clusters in the glasses. Bismuth-tantalum-codoped germanium oxide glass might be promising as amplification media for broadly tunable lasers and wideband amplifiers in optical communications. (c) 2005 Optical Society of America.

植物形态学信息处理的研究

从计算机技术的角度出发，对植物形态学信息处理和应用，构成本文的思想，文中简略同顾了植物形态学术语的标准化的历史发展过程，对当前世界范围内在此领域的工作也作了概要般的总结，论述了计算机技术用十植物学应用和研究的重要性并提出了我国在此领域内开展工作的紧迫性和必要性。计算机的资源限制及植物信息特有的复杂性是这一领域发展的困难。因此，如何贮存植物信息?如何操作加工应用？才能充分利用计算机资源和植物信息资源成为本领域的核心问题。 本文基于上面的考虑，对植物形态学信息从基本的信息单位植物形态学术语出发，探求其分类结构，并从计算机技术的编码理论方面进行探讨．力图求得一个标准化的植物形态学描述分类群的术语编码集，提供一种实现描述的方法，并试验性地给出一种描述规范和格式，简单讨论一下实现语言处理，机器鉴定、数量分类的可能性，最后简单分析和对比了本工作和国际上的类似工作，并对本领域进行了简单的展望。

变异铁角蕨及其一些近缘种的生物系统学的研究

本文通过形态学、孢粉学和细胞学观察，并借助等位酶分析手段，阐明了变异铁角蕨复合体中一些四倍体种的起源问题：北京铁角蕨(A. pekinense Hance)是二倍体华中铁角蕨（A.sarelii Hook.）的同源四倍体，四倍体华中铁角蕨是二倍体华中铁角蕨和细茎铁角蕨(A. tenuicaule Kayata)或近缘种的异源四倍体，云南铁角蕨（A. yunnanense Franch.）是二倍体泸山铁角蕨（A. lushanense C.Chr.）的同源四倍体，变异铁角蕨（A. varians Wall.）是同源或部分同源四倍体。本文还对二倍体华中铁角蕨、泸山铁角蕨、虎尾铁角蕨(A.mcisum Thunb.)的遗传多样性和遗传学距离进行了计算，结果表明三个种的遗传学界限是清楚的，二倍体华中铁角蕨具较丰富的遗传多样性。同时，三个天然杂种——龙门铁角蕨(A. pekinense x A. varians)、京云铁角蕨(A．pekinense x A. yunnanense)和吉多铁角蕨(A. pekinense x A. sarelii) ——被发现，并被等位酶资料所证实。