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81.
将在动量空间具有积分形式的单胶子交换梯形近似下Bethe-Salpeter方程化为微分方程,求出该方程在四动量为零时的赝标解全部分量,其中第一分量为已知的Goldstein解. 相似文献
82.
Menger FM Bian J Seredyuk VA 《Angewandte Chemie (International ed. in English)》2004,43(10):1265-1267
83.
LiJunjie BianBaojun 《高校应用数学学报(英文版)》2000,15(3):273-280
The following regularity of weak solutions of a class of elliptic equations of the form are investigated. 相似文献
84.
85.
傅里叶变换轮廓术中新的相位及高度算法分析 总被引:1,自引:0,他引:1
在传统傅里叶变换轮廓术三维面型测量中,为了准确得到被测物体的高度分布,必需保证投影仪出射光瞳和摄像机入射光瞳的连线与参考面平行并且在同一水平面,否则存在较大的误差。着眼于更普通的情况,讨论双瞳连线与参考面成某一夹角时的高度计算,推导出了非平行时的参考面光场及物面变形条纹光场的表达式,并给出了高度映射公式。因而,传统的傅里叶变换轮廓术测量成为角度α=0时的特例。该方法使傅里叶变换轮廓术的测量条件得到了放宽;易于通过移动投影装置或成像装置获取全场条纹;并为在难以实现双瞳与参考面平行的特殊环境下的测量提供了可行的方法。计算机模拟及实验均证实了该方法的有效性。 相似文献
86.
We present in this paper a highly stable and efficient KTP-based intracavity optical parametric oscillator with a diode-end-pumped
Nd:YVO4/Cr:YAG passively Q-switched laser. At the incident diode pump power of 4 W, the signal (1.57 μm) and idler (3.29 μm) average
output powers up to 580 and 100 mW, respectively, have been achieved. The corresponding conversion efficiency from the input
diode pump power to the output signal power is 14.5%, while that to the total OPO output (signal+idler) reaches 17%. To the
best of our knowledge, these are the highest conversion efficiencies reported to date. After more than four hours of investigation,
the OPO power stability better than 2% has been obtained. In addition, efficient cavity dumping of the IOPO has inevitably
led to the short pulse duration (1.6 ns) and high peak power output (8.3 kW) at the signal wave. Additionally, the amplitude
and repetition rate fluctuations of the signal pulses are well within 5%.
PACS 42.55.Xi; 42.60.Gd; 42.60.Lh; 42.65.Yj 相似文献
87.
小波变换轮廓术的测量范围研究 总被引:2,自引:1,他引:2
利用小波“脊”处的小波系数来提取变形条纹中的相位信息可以在很大程度上抑制条纹图中有用的基频分量与零频和其它谐波频率分量的混叠,弥补了傅里叶变换轮廓术的不足。从离散信号频域分析角度,推导了变形条纹小波变换的频谱描述形式,讨论了其测量范围,包括结构条件和抽样条件。结果表明,只有在无周期内瞬时频谱混叠,即任意位置处物体瞬时高度变化满足h/xx=b<1/3条件时,和不存在抽样引起的周期间瞬时频谱混叠的抽样条件下(即一个周期内的抽样点数m≥4时),小波变换轮廓术才能正确恢复被测物体的三维面型。计算机模拟和实验验证了该结论。 相似文献
88.
Strength characteristics of the self-sustained wave in grooved channels with different groove length
Faming Sun Yongning Bian Hirofumi Arima Yasuyuki Ikegami Xinsheng Xu 《Heat and Mass Transfer》2010,46(11-12):1229-1237
The self-sustained oscillations arising in a series of grooved channels are investigated experimentally. Pressure drop, time-averaged and time-various local pressure in the grooved channels with six kinds of groove length are measured with the differential transducer and the pressure sensor, respectively, and the flow structures are visualized using the aluminum dust method. The local pressure signal shows that the self-sustained wave appears in the first or second frequency, and the Strouhal number, based on the nature frequency of the self-sustained wave, is almost equivalent for the first or second frequency in the same channel. Meanwhile, the Strouhal number for each channel decreases monotonously with the groove length. Furthermore, it is found that increasing pressure will result in higher amplitude of the self-sustained wave, this behavior is significant for the efficient heat transfer in practical engineering. 相似文献
89.
Tianfa Wen Jianping Gao Jiuming Zhang Beiya Bian Juyun Shen 《Infrared Physics & Technology》2001,42(6):241-508
A metallic (Ag)–dielectric (AgI) hollow glass waveguide is a promising and flexible fiber for the delivery of high-power CO2 laser radiation. The thickness of metallic (Ag) films and dielectric (AgI) films is a critical factor which greatly influences the attenuation of the waveguides. In this paper, metallic (Ag)–dielectric (AgI) films were successfully prepared in the capillary whose inner diameter is 0.53 mm, and firstly investigated with theoretical analysis and measured by means of AES and SEM. There is good agreement between theoretical thickness and experimental results, which confirms the validity of the theoretical analysis, which makes the estimate of the thickness of both the metallic and dielectric films possible with high accuracy prior to the preparation of hollow glass waveguides. The attenuation spectra of Ag/AgI hollow waveguides shows the loss increases with the thickness of Ag, AgI films and indicates that the Ag/AgI hollow waveguide is suitable for the transmission of IR radiation. 相似文献
90.
The characteristics of the electronic transition energy of Coumarin 120 (C120) and its H‐bonded complexes in various solvents have been examined by time‐dependent density functional theory (TDDFT) in combination with a polarizable continuum solvent model (PCM). Molecular structures of C120 and its H‐bonded complexes are optimized with the B3LYP method in PCM solution, and the dihedral angle H14? N13? C7? H15 is dependent on solvent polarity and the type of H‐bond. A linear correlation of the absorption maximum of C120 with the solvent polarity function is revealed with the PCM model for all solvents except DMSO. The experimental absorption maximum of C120 in nine solvents is well described by a PCM–TDDFT scheme augmented with explicit inclusion of a few H‐bonded solvent molecules, and quantitative agreement between our calculated results and experimental measurements is obtained with an average error of less than 2 nm. H‐bonding at three different sites shifts the absorption wavelength of C120 either to the blue or to the red, that is, a significant role is played by solvent molecules in the first solvation shell in determining the electronic transition energy of C120. The dependence on the H‐bonding site and solvent polarity is examined by using the Kamlet–Taft equation for solvatochromism. 相似文献