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101.
采用可变长度单摆的力学模型对秋千振荡给出初等分析,采用微扰近似法导出了秋千的非线性参数共振解析解,并进行了讨论。 相似文献
102.
The self-Q-switched laser performance of monolithic Cr4+,Nd3+:YAG concave-planar resonator with 5-mm length was studied experimentally and theoretically. The slope efficiency is as high as 24% and pump threshold is as low as 64 mW. The pulse width, the single pulse energy and the pulse repetition rate of monolithic Cr,Nd:YAG self-Q-switched laser were measured as a function of absorbed pump power. With the increase of pump power, the pulse width decreases and the pulse energy and the pulse repetition rate increase. The average output power of 91 mW with pulse width of 7 ns at repletion rate of 35.5 kHz was obtained at the maximum absorbed pump power of 440 mW, the peak power is as high as 370 W. The theoretical prediction of pulse energy, pulse width and pulse repetition rate as a function of absorbed pump power based on rate equations is in a good agreement with our experimental data. This can lead to develop the diode laser-pumped monolithic self-Q-switched solid-state microchip lasers. 相似文献
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104.
Yu. Satov B. Sharkov H. Haseroth Yu. Smakovski K. Makarov S. Kondrashev V. Roerich A. Stepanov H. Kugler R. Scrivens O. Camut A. Shumshurov A. Balabaev A. Charushin 《Journal of Russian Laser Research》2004,25(3):205-216
Experimental and numerical calculation results devoted to development of an optical system for an ion source based on a repetition rate CO2 laser are described. The laser chain consists of a master oscillator, gas absorber cells, and a four-pass amplifier. The optical system provides smooth laser pulses with variable duration and high spatial quality that ensures efficiency for plasma heating and ion generation. The parameters of the plasma ion component measured in the CERN laboratory are applied for a lead target illumination. 相似文献
105.
An experimentally validated finite element method is used to model the sound level in rooms at low frequencies. It is demonstrated that the dimensions of rectangular rooms strongly influence the sound pressure level difference. Additional factors were investigated which are not normally considered in the frequency range where diffuse sound field conditions can be assumed. Three effects were investigated: room damping due to wall vibrations, furniture, the effect of small deviations from simple rectangular shapes. It is confirmed by field measurements that the vibrations of masonry walls and floors introduce less damping than surfaces of lightweight construction. Assigning to the FE model a damping equivalent to a surface absorption of 0.02 reproduces the effect of walls of heavyweight construction. Damping equivalent to a surface absorption of 0.15 reproduces the effects of plastered timber-frame walls, floors and ceilings. The work was briefly extended to a room pair built with heavyweight and lightweight material of construction. The modification of the shape of the room frequency response highlights well the effect of material of construction. In-situ and laboratory measurements show that furniture has little effect on steady-state room response below 100 Hz. Modelling a wall recess smaller than 0.5 m improved the agreement between prediction and measurements but the assumption of a simple rectangular room remains appropriate. 相似文献
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109.
基于Polytec激光测振仪的光存储设备振动测试分析系统 总被引:2,自引:0,他引:2
针对光存储设备振动频率高的特点,采用Polytec激光测振仪拾取振动信号,并给出了基于Polytec激光测振仪的光存储设备振动测试分析系统。可用于硬盘盘片、磁头滑块、折臂组件、光盘盘片等振动测试,为光存储设备动态特性的测试和分析建立了良好的实验基础。 相似文献
110.
V. M. Andrianov 《Journal of Applied Spectroscopy》2007,74(1):1-12
A theoretical conformational analysis has been carried out for the side substituents of a fragment of the molecule for 2,6-carboxymethyl
cellulose (a water-soluble cellulose ether), and the frequencies and the potential energy distribution of the normal vibrations
have been calculated for the most stable conformers of the ether groups of this fragment in the approximation of the molecular
mechanics method. It has been shown that the most stable conformers are those that have the conformations gg, t, g−, g−, g−-for the groups of atoms on the bonds C5-C6, C6-O6, C13-O6, C10-C13, C10-O9 and the conformations g+g−, g+, g−, g−; g+g−, g−, g−, g−; g+g−, g−, g+, t for the groups of atoms on the bonds C2-O2, C11-O2, C7-C11, C7-O8. Comparative analysis of the calculated frequencies
and the potential energy distribution of the normal vibrations for 13 of the most stable conformers showed, as in the case
of the 2,6-hydroxyethyl cellulose molecule, that the frequencies and modes of the normal vibrations are highly sensitive to
conformational transitions in the analyzed spectral region (800–1500 cm−1). The characteristic patterns for the change in the frequencies and modes of the normal vibrations have been established
in connection with conformational transitions within both side substituents. The observed conformational lability of the bulky
substituents in the cellulose ether molecules and its manifestations in the vibrational spectrum provide a basis for hypothesizing
that one of the major mechanisms for the process of their thermal gelation in aqueous solutions is conformational transitions
within these substituents.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 5–15, January–February, 2007. 相似文献