Compact Single-Stage Femtosecond Multipass Ti：Sapphire Amplifier at 1 kHz with High Beam Quality

A compact femtosecond Ti：sapphire amplifier system is reported using single-stage multipass configuration with high beam quality. A high dispersion glass stretcher and a pair of double prisms for compression are introduced based on broadband femtosecond seed pulses. The non-grating-based pulse stretcher and compressor are advantageous to increase high beam quality and to reduce the high-order dispersion. A Gaussian filter is used to reduce the gain narrowing effect in amplification. The compact femtosecond Ti：sapphire nine-pass amplifier delivers pulses with a duration of 26 fs and an energy of 800μJ at 7mJ pumping pulses energy at I kHz. The 1-kHz femtosecond amplifier with high beam quality and high stability is very suitable for ultrafast physics research applications, such as attosecond science, ultra-precision micromachining, and THz wave generation.     

三维Minkowski空间中的曲面及其可积性

利用可积系统的思想,借助三维Minkowski空间L3的矩阵模型,研究了L3中具有调和逆平均曲率的类空曲面和洛伦兹调和逆平均曲率类时曲面的可积性及其形变.     

有限体积KFVS方法在二维溃坝中的应用

本文采用了基于KFVS格式的有限体积方法 (FVM)求解了控制水流运动的二维浅水方程 ,建立了二维水坝瞬间溃坝的洪水演进模型 .并应用此模型模拟了二维非对称溃坝和对称溃坝情形下坝左下角有障碍物时的洪水波演进过程 .模拟结果表明该数学模型对二维浅水运动的模拟很有效 .     

XML数字签名在高校教务管理系统中的应用

作为高校数字化校园的一部分,教务管理系统正在由功能型向安全高效型转变.文中研究了在教务管理系统中利用XML数字签名取代原本需要手工签名的方法,给出了一个具体的创建证书、签名、验证的实现过程.     

Detecting myocardial ischemia with 2-D CVIB imaging method--an in vivo animal experiment study

A 2-D cyclic variation of integrated backscatter (CVIB) imaging method was established for detecting myocardial ischemia. To demonstrate the feasibility and validity of this method, animal experiments were conducted. Acute myocardial ischemia was induced by occluding left anterior descending coronary artery in 10 anesthetized open-chest dogs. While scanning the normal hearts and the ischemic hearts with a B scanner, digital radiofrequency data were acquired by a real-time acquisition system in synchronism. The offline analysis to the radio-frequency signal with the 2-D CVIB imaging method was performed to verify the consistency between the imaging result and the design of the experiment. In addition, 4 dogs in experiment were treated with the heart pacemaker in order to investigate the influence of changing in heart rate on the detection of ischemic myocardium with the proposed method. The experimental result showed that the 2-D CVIB imaging method succeeded in detecting the ischemic myocardium and is a new non-invasive way for the cardiologists to both quantitatively and visually evaluate the contractile performance of the myocardium.     

对非英语专业大专生学习方式的调查

对广州部分非英语专业大专生英语学习方式的一次抽样调查和分析表明，非英语专业的大专生最喜欢的学习方式是动手学习方式，最不喜欢的是小组学习方式；女生比男生更明显偏爱动手学习方式；高分组的学生在动手和小组学习方式上的平均分明显高于低分组学生。因此，教师在根据学生不同的学习方式采取灵活多样授课方式的同时，应对学生的学习方式加以有效指导，使学生注意改善并扩展自己的学习方式，从而提高学习效果，取得事丰功倍的学习效果。     

甲烷与水分子氢键相互作用的理论研究

使用Gaussioan94程序包，在B3LYP／6—311G**基组水平上，对甲烷(CH4)与水分子(H2O)之间的所有相互作用方式进行优化．通过电子布居分析，发现在电子给予体O原子和电子接受体H原子间存在氢键，氢键的键长约为0．2574nm．振动模式分析表明，只有一种加合物是稳定的，势能面也证实了这一点．     

Molecular dynamics study on the structure I helium hydrate

A 368- water molecule structure I gas hydrate, encased by the number of helium (He) molecules ranging from two to twenty-two, are calculated by molecular dynamical simulations. The potential TIP4P (transferable intermolecular potentical with four sites) is used for water interactions and Lennard-Jones for He-He and He-water interactions. He molecules do not affect the water lattice and can stabilize the hydrate when their concentration is small. A trough signature of He encased is found at 80～90 meV in the phonon density of states. He molecules prefer to be more off-center in 51262 cages. Heavier isotope He are energetically favorable to be filled in cages.     

高师院校学生数学学习模式研究

本文通过对调查结果的分析,研究了高师院校数学学习模式的现状,提出改进学习模式的若 干建议。     

基于改进等分节点法的启发式布局算法

针对集成电路标准单元模式的布局问题，提出了一个全新的基于改进等分节点法的启发式标准单元布局算法(TETP)，该算法在优化布局过程中采用改进的等分节点法寻找单元目标位置，同时结合局部寻优的启发式算法，对MCNC(Microelectronics Centre of North-Carolina)标准单元测试电路进行实验。结果表明，与布局工具Timber Wolf7．0和FengShui相比，电路布局的总线长度分别平均减少了16％和17％。