非均质Timoshenko梁的边界镇定

In this paper,the boundary stabilization of the Timoshenko equation of a nonuniform beam,with clamped boundary condition at one end and with bending moment and shear force controls at the other end,is considered.It is proved that the system is exponentially stabilizable when the bending moment and shear force controls are simultaneously applied.The frequency domain method and the multiplier technique are used.     

钠原子光电离过程中角分布参数β的计算

运用多体微扰理论方法 ,对开壳层钠原子的内壳层电子的光电离过程2p⁶3s→ 2p⁵ 3skl中分波散射截面和角分布参数进行了计算 .在计算中包括了 2s→ 3p的共振结构 .同时利用多体微扰理论的图式 ,对主要的电子关联相互作用进行了分析 ,并对RPA和BO关联的主要贡献项计算达到了无穷级近似 .计算结果与实验吻合较好 .     

手性Salen-Ni(Ⅱ)络合物的ECD光谱及其绝对构型关联:可见区第一ECD吸收带的指纹作用

对系列手性salen-Ni(Ⅱ)络合物的电子圆二色(ECD)光谱及其绝对构型关联进行了概述.根据晶体结构和对固、液ECD光谱的表征,结合理论计算,着重探讨了准平面型手性[Ni(salen)]的固态结构及其在溶液中的绝对构型和优势构象.在此基础上通过若干实例说明了平面四方形[M(salen)]络合物两种绝对构型命名法,并给出了我们的建议.对[Ni(sal-R, R-chxn)] [sal-R, R-chxn = (R, R)-N, N'-双(亚水杨基)-1, 2-二亚氨基环己烷]的二氯甲烷溶液ECD光谱的计算结果表明,可见区第一个ECD吸收带主要是π →d荷移跃迁(LMCT)所致,而不是通常认为的d-d跃迁: [Ni(sal-R, R-chxn)]的绝对构型为Λ,其在可见区第一个ECD吸收带为正.将此ECD指纹应用于具有“闭壳层”电子结构的其它平面型手性[Ni(salen)]和六配位trans-[Co^Ⅲ(salen)L₂]络合物的绝对构型指认,具有一定的普适性.本文的研究结果对于深入理解手性[M(salen)]络合物的配位立体化学、手征光学性质及其手性识别和不对称催化机理具有重要科学意义.     

偏振效应损伤的光通信系统失效概率估算

采用多重重要抽样方法,研究了受偏振模式色散和偏振相关损耗损伤的10 Gbit/s光通信系统的功率代价和失效概率.仿真结果表明,光滤波器对功率代价有重要影响.采用法布里-珀罗滤波器的系统比采用四阶高斯型滤波器的系统有更好的性能表现;发现功率代价通常随着啁啾因子的增大而增大,但当啁啾因子为0.5左右时,系统性能达到最好.仿真结果也表明,即使偏振模式色散和偏振相关损耗同时存在,DPSK系统比OOK系统有更强的PMD和PDL耐受性.     

Charge transfer of 1 ML C60/Ag（100）

We have measured the synchrotron radiation photoelectron spectra of monolayer C60on Ag（100）, By calculating the intensity ratios between the LUMO bands and the two deeper bands （HOMO and HOMO- 1）, we estimate the amount of the charges transferred from Ag（100） to C60 within the range of 1 e to 1.8 e. The results dismay the expectation of surface superconductivity and afford a good reference for further studies of the monolayer C60/Ag（100） system.     

关于化学专业科技英语教学的几点建议

就化学专业科技英语教学,我们提出几点建议,分别为使学生明确科技英语定义特征、课堂教学与科研生产实例有机结合、采用灵活多样的教学手段、利用好课后作业环节巩固学习效果。希望通过课堂教学和课后作业布置等环节的改进,使高年级的化学及化学相关专业本科生的科技外语水平在1~2个学期内取得较显著的提高。     

基于光纤SPR光谱分析的水质矿化度检测研究

从溶液离子影响表面等离子体共振(SPR)光谱特征的角度,分析讨论了光纤SPR光谱对水溶液离子成分检测的灵敏特征,基于此并应用于以矿化度为代表的水质检测中。研究通过对不同离子状态的电解质溶液(NaCl,KCl,CaCl₂,MgCl₂,Na₂CO₃,MgSO₄和ZnSO₄)和非电解质溶液(蔗糖、丙三醇、葡萄糖)下的光纤SPR光谱分析,得到水环境的杂质离子含量对SPR光谱的影响规律,进而实现了水质矿化度的检测。研究同时给出了光纤SPR光谱法与电导率分析法在八种不同水样的检测对比分析,光纤SPR光谱法拥有高灵敏度、快速响应、抗电磁干扰等优点,对光纤SPR技术在水质检测领域的应用打下良好的基础。     

PGAI瞬发伽玛射线活化成像技术理想化模型的模拟

为了讨论PGAI技术分析的准确性,并验证冷中子和热中子应用于PGAI技术的可行性,通过蒙特卡罗模拟计算软件对PGAI技术理想化模型进行了研究,采用高准直的冷中子及热中子束和高纯锗探测器,对一块5 cm× 5 cm×1 cm均匀铁单质样品进行了模拟计算及图像重建,选取的等效体积大小为1 cm×1 cm×1 cm。结果显示:两种能量中子可以用于PGAI技术实现元素分布测量,但无论使用何种能量中子,由于物料体效应带来的中子自屏效应、中子散射效应以及伽马射线自吸收作用,即便在对均匀单质样品进行测量时,图像重建结果也无法保证各位置元素响应的一致性。因此,在后续工作中,需理清PGAI物理机制,建立相应的修正模型。     

Attosecond laser station

The attosecond laser station(ALS) at the Synergetic Extreme Condition User Facility(SECUF) is a sophisticated and user-friendly platform for the investigation of the electron dynamics in atoms, molecules, and condensed matter on timescales ranging from tens of femtoseconds to tens of attoseconds. Short and tunable coherent extreme-ultraviolet(XUV)light sources based on high-order harmonic generation in atomic gases are being developed to drive a variety of endstations for inspecting and controlling ultrafast electron dynamics in real time. The combination of such light sources and end-stations offers a route to investigate fundamental physical processes in atoms, molecules, and condensed matter. The ALS consists of four beamlines, each containing a light source designed specifically for application experiments that will be performed in its own end-station. The first beamline will produce broadband XUV light for attosecond photoelectron spectroscopy and attosecond transient absorption spectroscopy. It is also capable of performing attosecond streaking to characterize isolated attosecond pulses and will allow studies on the electron dynamics in atoms, moleculars, and condensed matter. The second XUV beamline will produce narrowband femtosecond XUV pulses for time-resolved and angle-resolved photoelectron spectroscopy, to study the electronic dynamics on the timescale of fundamental correlations and interactions in solids, especially in superconductors and topological insulators. The third beamline will produce broadband XUV pulses for attosecond coincidence spectroscopy in a cold-target recoil-ion momentum spectrometer, to study the ultrafast dynamics and reactions in atomic and molecular systems. The last beamline produces broadband attosecond XUV pulses designed for time-resolved photoemission electron microscopy, to study the ultrafast dynamics of plasmons in nanostructures and the surfaces of solid materials with high temporal and spatial resolutions simultaneously. The main object of the ALS is to provide domestic and international scientists with unique tools to study fundamental processes in physics, chemistry,biology, and material sciences with ultrafast temporal resolutions on the atomic scale.