铁基合金激光熔覆组织及高温时效转变的TEM研究

利用ATEM研究了铁基多元合金Fe-Cr-W-Ni-C激光熔覆层的微观组织、亚稳相结构特征以及高温时效时的亚稳相转变机制。结果表明组织为亚共晶组织，即γ+(γ+M_7C_3)，γ-奥氏体为具有较高合金度的过饱和亚稳相，M_7C_3(M为Cr,Fe,W)为六方结构的Cr基亚稳合金碳化物。熔覆组织在高温时效时存在两类碳化物形成机制，即亚稳γ中析出M_(23)C_6、M_2C与MC碳化物以及M_7C_3→M_(23)C_6与M_7C_3→M_6C的碳化物原位转变机制。熔覆组织具有较高的显微硬度并存在显著的二次硬化特征。

Mapping Closure Approximation for Reactive Scalars in Random Flows

The Mapping Closure Approximation (MCA) approach is developed to describe the statistics of both conserved and reactive scalars in random flows. The statistics include Probability Density Function (PDF), Conditional Dissipation Rate (CDR) and Conditional Laplacian (CL). The statistical quantities are calculated using the MCA and compared with the results of the Direct Numerical Simulation (DNS). The results obtained from the MCA are in agreement with those from the DNS. It is shown that the MCA approach can predict the statistics of reactive scalars in random flows.

激光冷却铷原子喷泉钟的微波谐振腔设计

对自行研制的激光冷却铷原子喷泉钟的微波谐振腔进行了分析和设计，确定了需要的微波谐振腔基本参数。对影响微波谐振腔共振频率的因素进行了分析和研究，得到了共振频率随环境因素的变化规律。这些对调节微波腔共振频率和提高原子钟的准确度有重要意义。还对研制的微波谐振腔进行了测试，结果表明微波谐振腔的性能满足激光冷却铷原子喷泉钟的要求。由测试结果进一步估算了微波谐振腔引起的横向腔相移。

The origin of the transverse relaxation time in optically excited semiconductor quantum wells

The origin of the transverse relaxation time in optically excited semiconductor quantum wells is investigated based on the vector property of the interband transition matrix elements. The dephasing rate due to carrier-carrier (CC) scattering is found to be equal to half of the common momentum relaxation rate. The analytical expression of the polarization dephasing due to CC scattering in two-dimension is established and the dependence of the dephasing rate Gamma(cc) on the carrier density N is determined to be Gamma(cc) = constant (.) N-1/2, which is used to explain the experimental results and provides a promising physical picture. (C) 2004 Elsevier B.V. All rights reserved.

用原子芯片操纵中性原子

原子芯片提供了一个稳定、精确且功能强大的实验平台来制备和操纵中性超冷原子。本文概述了近年来原子芯片的研究发展状况，并介绍了原子芯片上微势阱的设计原理以及几个典型的原子芯片实验，然后讨论了芯片实验中的原子损失、加热和退相干机制，最后对原子芯片可能的发展方向进行了预测。

Stable single frequency and single polarization DFB fiber lasers operated at 1053 nm

Stable single-frequency and single-polarization distributed-feedback (DFB) fiber laser was realized by giving a pressure on the phase shift region of the fiber grating. The output wavelength of the DFB fiber laser is 1053 nm. When the pump power of 980 nm laser diode is 100 and 254 mW, the output power can reach 8.3 and 37.1 mW and the polarization extinction ratio was 26 and 20 dB, respectively. After chopped by Acousto-optic modulator (0.3 Hz), the pulse peak value variance is 4.65%(peak to peak) and 1.098% (RMS) for 31 min. (C) 2006 Elsevier Ltd. All rights reserved.

Temperature dependence of femtosecond laser induced refractive index change in Nd3+-doped phosphate glass

We report refractive index change in a femtosecond laser irradiated Nd3+-doped phosphate glass. The effects of annealing temperature on the refractive index change of the glass have been investigated. Absorption spectra of the glass sample before and after femtosecond laser irradiation and subsequent annealing were measured. The results indicate that multiphoton absorption can undertake although there are intrinsic absorption for the glass in irradiation wavelength. The results may be useful for fabrication of three-dimensional integrated optics devices and waveguide laser devices in this glass. (c) 2004 Elsevier B.V. All rights reserved.

广东省海岛资源综合调查

这次调查获取了大量具有历史价值的资料．其中包括广东海岛及其海域的自然条件、自然资源和社会经济条件的基本资料。海岛综合调查共登岛142个，占广东省759个面积大于500m2的海岛的18.7％，共布设调查断面316条，站点3919个，采样品7933个，采标本49000号．共获得资料数据104万多个；资料汇编288册；编制图幅1159幅，编写并出版海区调查报告7册，调查研究论文集3册、专业调查报告12册和100万字的《广东海岛资源综合调查报告》。广东海岛资源综合调查填补了广东海岛环境、资源综合调查的空白，不仅概括和揭示了海岛自然环境和自然资源的基本情况，而且揭示了海岛经济开发的规律，为发展当地经济作出了突出贡献。

植物群落复杂性与群落结构组建的描述与分析

时间、空间格局的保持和发展及其对种群、群落和生态系统动态的影响是生态学中两个相互关联的基本课题。围绕这个中心议题作者在植物个体、种群、群落各个层次上开展了研究。 1)研究了克隆植物构型及其对资源异质性的响应，给出了描述该连续体的一个指数v：In1/ln刀．（士

人工神经网络在植被遥感影像分类中的应用研究

比起传统的统计方法，人工神经网络具有很好的非线性处理和并行计算能力，在植被遥感信息处理中得到广泛的应用。本研究系统地介绍了人工神经网络理论及其在植被遥感信息处理中的应用现状。并就如何提高人工神经网络的相干被遥感影像的分类能力进行了详细研究。首次提出了结合植被指数和组成分分析的神经网络分类方法。过去这方面的研究工作大都集中在通过选择一个合适的神经网络模型来提高植被分类精度，而我们认为：根据植被遥感自身的规律，结合统计方法，确定合适的网络输入模式的特征变量，也可以提高分类精度。 研究结果表明，尽管一般的神经网络分类器不需要对输入的模式做明显的特征提取，网络的隐层就具有特征提取的功能。但对TM影像七个波段和常用的五个植被指数（PVI、NDVI、WDVI、PVI、MSAVI2），分别做主成分分析，从而获得人工神经网络输入的特征变量，使用这样一种结合VI、PCA的神经网络对遥感TM多波段影像进行植被分类，能大大提高分类的精度。