Dynamics of Efficiency Change by Temperature in Diode Pumped Nd：YAG Heat Capacity Laser

We investigate the influence of temperature on the efficiency of diode pumped Nd：YAG heat capacity laser is studied. It is shown that the efficiency of such a laser system is greatly reduced at higher temperature. This bad behaviour is mainly caused by the doped-ion redistribution among various Stark levels of the ground state, and by a thermal equilibrium between the upper laser level and the pump level. Meanwhile, the thermal excitations from the ground state to the lower laser level also play a role. We derive a model to describe those effects, with the considerations of emission spectrum of laser diodes, the subtle Stark structures and the linewidth of absorption and of simulated-emission.     

扫描相机标定脉冲信号位置的确定及噪声处理

 扫描相机标定数据处理中的一个关键问题是如何准确确定脉冲信号的位置，实验数据的信噪比和脉冲信号位置的定义方法都会对标定结果的准确性产生影响。采用了取半高宽的方法来确定扫描相机标定脉冲信号的位置，在信噪比比较高 （大于100） 的情况下，该方法确定标定信号的位置可以达到亚像素水平。对于信噪比比较低 (小于10) 的实验数据，先采用快速傅里叶变换方法对其进行滤波，通过滤波可以极大地抑制噪声信号的影响，然后采用“半高宽法”确定脉冲信号的位置，最后得出可信的标定结果。当扫描相机定在0.3 ns的扫描档时，通过该方法得到的扫描速度为0.214 ps/pixel,扫描不确定度为0.002 9 ps/pixel,拟合线性相关系数为0.999 7。     

基于截形式背景的属性约简分析

在模糊概念格中讨论了基于截形式背景的属性约简,其中着重分析了在精度的偏序关系下属性约简的包含关系,并证明了此说法的正确性,进而还举例说明了其正确性;在此基础之上,本文还给出了在用不同精度把模糊概念格转换了经典概念格时造成的误差,并给出其算法,最后举例说明其有效性.     

Relative position determination of a lunar rover using high-accuracy multi-frequency same-beam VLBI

Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas. In the same-beam VLBI, the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds. The differential phase delay, as the observable of the same-beam VLBI, gives the separation angular information of the two explorers in the celestial sphere. The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth, by using the differential phase delay obtained with the four Chinese VLBI stations. The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m.     

加权Herz型Hardy空间上的Littlewood-Paley g_λ~*函数

讨论了在q=2的情形下,Littlewood-Paley gλ*函数在加权Herz型Hardy空间中的有界性,即当0相似文献   

Structures and stability of N13 cluster

Quantum chemical studies for the nine N₁₃ isomers with low spin were carried out at the UHF/6-31G*, UB3LYP/6-31G* and UMP2/6-311G* levels of theory. The most stable N₁₃ isomer is structure 1 with C_2v symmetry, which contains two separated pentazole rings connected by three nitrogen atoms. The results show that structures 1, 2, 3, 4 and 5 which are composed of the pentazole ring are more stable than the open chain structure 6 and structures 8 and 9 which contain the four- and six-membered rings. This suggests that the pentazole ring is a fundamental stable structural unit, which is applicable not only for the even-numbered nitrogen clusters, but also for the large odd-numbered clusters.     

Morlet小波在确定局部周期中的应用

本文通过引入改进的Morlet小波变换核函数,得到了等幅值的Morlet小波变换(MMWT)和功率谱(MMPS).理论及实验均表明,MMPS不但能够准确的确定信号的局部周期,而且使相同振幅(强度)的谐波产生了相同大小的MMPS,弥补了MPS的不足.对于MMWT还给出了相应的Morlet小波变换尺度与频率转化公式.     

关于算子方程λA2+μA*2=αA*A+βAA*

本文主要是给出Hilbert空间上满足方程 λA²+μA^*2=αA^*A+βAA^* (λ,μ,α,β都是复数)的有界线性算子A的全部形式,并给出它的应用。     

主动成像系统距离选通实验方案设计

 距离选通技术是克服大气后向散射，提高主动成像系统信噪比的有效方法。分析了距离选通的技术要求，分别使用电源调制和机械调制的方法获得了适合用于主动成像系统脉冲光源,并进行了距离选通实验，机械调制方法适用于大功率连续半导体激光器。使用氙灯泵浦YAG激光器实现了对675 m和1 509 m距离目标的主动成像，详细分析了几种方案的利弊并提出了改进方法。     

非负整数格上元素的性质及其在刻画@-Fuzzy关系方程解集中的作用

首先讨论了非负整数格上元素的性质. 从而完全地刻画了非负整数格上@-Fuzzy关系方程(其中@表示inf-α合成)的解集.