For ultrashort few - cycle pulses , the group velocity dispersion should be considered , whose influence depends on the parameters of the beam and the material 对于几个光周期的超短脉冲，除透镜色差外，还应当考虑群速度色散，且其影响依赖于透镜材料和光束参数。
After doing the modifying of machine in calculating the real amplitude and frequency - time analysis to all selected records , the group velocity was calculated for each seismograms 对这些地震记录做仪器频响特性校正，同时进行频时分析( ftan ) ，求其群速度频散。
In general , the lens chromatic aberration and the group velocity dispersion lead to a broadening in the temporal and spatial intensity distributions at the focal plane and a decrease o 一般说来，透镜色差和群速度色散会使焦平面上脉冲光束的时间、空间光强分布展宽，峰值光强降低。
Secondly , wavelet transform is applied to compute the arrival time of the lamb wave group velocity experiments results demonstrate that wavelet transform can improve the precision of damage localization 其次，本文采用小波分析方法提取lamb波群速度的到达时间，获得了比阈值法及互相关方法更高的精度。
( 2 ) calculating the gridded rayleigh wave attenuation factor y and group velocity . the lsqr algorithm is used to inverse the attenuation factor and group velocity under 4 ? x4 ? gridding and 2 ( 2 )进行rayleigh波衰减系数、群速度网格化纯路径衰减反演计算，得到网格单元纯路径衰减系数和群速度分布结构。
Under certain conditions , in spite of their different modal indices the two polarized components of the pulse can trap one anther and move at a common group velocity due to xpm , the phenomenon referred as self - trapping occur 在一定条件下，尽管脉冲的两个偏振分量的模式折射率不同，但由于交叉相位调制效应，它们能相互俘获并以共同的群速度传输，产生自捕获现象。
By using transducers with different central frequency and diameter , the approximate demands for the length of those samples and the transducers " frequency and diameter were presented in order to attain the phase or group velocities in the experiment 通过多种频率和不同直径的换能器，给出了实验室测试各向异性介质相速度和群速度时换能器频率和直径与样品长度之间的相对关系。
Generally speaking , the high group velocity and low attenuation factor and high qr in the same area , but relatively low group velocity and high attenuation factor and low qr in the same area in china is the general distribution 在不同周期，面波衰减系数或品质因子在整个中国大陆区域分布是不均匀的；总体表现为高群速度分布的区域呈现高丛和低衰减系数、低群速度分布的区域呈现低丛和高衰减系数分布的特点。
We derive an analytic expression of the group velocity dispersion ( gvd ) induced chirp and the self - phase modulation ( spm ) induced chirp in the normal dispersionregion of non - kerr - like optical fibers with saturable nonlinarity . the evolution of chirp is simulated by numerical methods . the studied results show that the more powerful saturable effects , the smaller is chirp and the gently is chirp . the net chirp is zero in the central region of the pulse 从理论上推导出具有饱和非线性的非克尔光纤正常色散区内，群速度色散效应导致的啁啾和自相位调制效应导致的啁啾解析表达式.利用数值解法模拟了非克尔光纤正常色散区啁啾演变过程.研究结果表明：当非克尔光纤的饱和非线性增强时，净啁啾不断减小，而且，越来越平缓，脉冲中心附近区域净啁啾接近零
The phase matching and group velocity matching conditions of type - i and type - ii second harmonic generation ( shg ) are obtained according to the momentum and energy conservation laws . the group velocity delay of ultrashort pulse shg on clbo and the crystal length decided by the group velocity delay are analyzed and compared with bbo ' s 从动量守恒、能量守恒出发推导得出了超短脉冲倍频的类、类相位匹配和群速匹配条件，对clbo晶体用于超短脉冲倍频时的群速延迟以及由群速延迟决定的晶体长度进行了分析和数值模拟，并与bbo晶体进行了比较。
