Time-resolved spectroscopy for 5s~('4)D_(7/2) state transitions undergoing electron–ion recombination in femtosecond laser-produced copper plasma

In the femtosecond laser-produced Cu-plasma, the transient transition dynamics that the excited state 5s~('4)D_(7/2) via electron–ion recombination transfers to 4p~('4)F_(9/2)~0(465.11 nm, Λ1 line) and 4p~('4)D_(7/2)~0(529.25 nm, Λ_2 line) states are investigated by using the time-resolved spectroscopy. The occupation number and relevant lifetime of the excited state 5s~('4)D_(7/2),the temporal evolutions of spectral intensities for Λ_1 line and Λ_2 line emissions are demonstrated to be in direct proportion to the employed laser intensity, which reveals the transient features of transition dynamics clearly differing from that resulted in the traditional collision excitation. Furthermore, some unique characteristics for Λ_1 and Λ_2 transitions stemming from electron–ion recombination are examined in detail.     

灰色网络计划中的关键线路确定方法研究

由于目前区间灰数的表征和运算过程存在着运算结果对灰数的灰度进行不必要的放大,造成信息的严重失真的问题,所以在灰色网络计划中计算出的工作总时差也有不同程度的放大,这时再根据工作总时差为零或最小的方法来确定关键线路则是不准确的.给出了确定灰色网络计划关键线路可以根据关键线路上总工期最长的方法,简单易行,且有效避免了灰数运算对灰数灰度放大的问题.     

Effect of metal surface morphology on nano-structured patterns induced by a femtosecond laser pulse and its experimental verification

The effect of material surface morphology on the periodic subwavelength of nano-structures induced by a femtosecond(fs) laser was investigated systematically from the initial surface roughness, the different scratches, the pre-formed ripples, and the "layer-carving" technology experiments. The results of the comparative experiments indicate that the initial surface conditions of the target surface have no obvious effects on the spatial structured periods(SSPs) and the ripple orientation of the periodic nano-structures induced by a fs laser, which agreed well with the foretold present surface two-plasmon resonance(STPR) model. Furthermore, different shapes of nanogrids with high regularity and uniformity were obtained by fs-laser fabrication.     

基于Hartley变换的三维真振幅偏移算子研究

在实际应用中，以快速Fourier变换为基础的偏移方法，将本来是实数的地震道转化为复数参加运算，导致了计算机内存的增加。本文把只有纯实数运算的Hartley变换引入到基于Fourier变换的偏移算法，再利用三维真振幅偏移单程波方程，结合Fourier变换与Hartley变换的内在关系，经过数学推理，具体导出了裂步Hartley变换真振幅偏移算子。与一般裂步Fourier法相比，裂步Hartley变换真振幅偏移算法既提高了计算效率又对球面扩散问题进行了振幅补偿。