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981.
Chun Gen Liu 《数学学报(英文版)》2005,21(2):237-248
In this paper, we consider the relation of the Morse index of a closed geodesic with
the Maslov–type index of a path in a symplectic group. More precisely, for a closed geodesic c on
a Riemannian manifold M with its linear Poincaré map P (a symplectic matrix), we construct a
symplectic path γ(t) starting from identity I and ending at P, such that the Morse index of the closed
geodesic c equals the Maslov–type index of γ. As an application of this result, we study the parity of
the Morse index of any closed geodesic.
Project 10071040 supported by NNSF, 200014 supported by Excellent. Ph.D. Funds of ME of China, and PMC
Key Lab. of ME of China 相似文献
982.
Dispersive two-beam Fourier interferograms of N2-gas in the visible wave number range are calculated numerically for nonabsorbing as well as absorbing gas and compared with experiment. Some problems of inverse Fourier transformation of dispersive interferograms are also discussed. 相似文献
983.
984.
The chemistry of N2H4 on Si(100)2 × 1 and Si(111)7 × 7 has been studied using scanning tunneling microscopy. At low coverages on Si(100)2 × 1 at room temperature the adsorption sites are distributed randomly on the surface and are imaged as dark spots in the dimer row by the STM. Upon annealing the substrate at 600 K, both isolated reaction products, as well as clusters of reaction products are formed on the surface. The STM images show that the majority of the isolated reaction products are adsorbed symmetrically across the dimers. Based on previous HREELS data, these are most likely NHx groups. However, the clusters are not well resolved. Because of this we speculate that they are not simply symmetrically adsorbed NHx groups, but likely have a more complicated internal structure. At higher coverages, the STM images show that the predominant pathway for adsorption is with the N---N bond parallel to the surface, in agreement with HREELS studies of this system. On Si(111)7 × 7, the molecule behaves in a manner which is similar to NH3. That is, at low coverages the molecule adsorbs preferentially at center adatoms due to the greater reactivity of these sites, while at higher coverages it also reacts with the corner adatoms. 相似文献
985.
986.
渐变折射率光波导的精确分析 总被引:7,自引:5,他引:2
本文利用转移矩阵理论和等效衰减系数的概念,导出了渐变折射率光波导的色散方程,数值计算的结果,赢余方程的精度优于目前存在的所有近似方法。 相似文献
987.
988.
芳香族共聚酯液晶的椭圆偏振光谱与光学性质的研究 总被引:1,自引:0,他引:1
应用自动化椭圆偏振光谱和紫外-可见光谱表征了两种芳香族共聚酯液晶的光学性质,发现由于分子结构和受激发电子振动跃迁的不同,使共聚酯液晶薄膜具有不同的折射率变化,产生不的同光学色散现象。 相似文献
989.
Surface defects created on Ge(001) exposed to low energy Xe ions are characterized by in situ scanning tunneling microscopy (STM). The temperature of the sample during ion bombardment is 165 C and ion energies range from 20 to 240 eV. The ion collisions create defects (vacancies and adatoms) which nucleate and form vacancy and adatom islands. For fixed total vacancy creation, the vacancy island number density increases with increasing ion energy: the vacancy island number density is 1.6 × 10−20 cm−2 for 40 eV ion bombardment and increases to 4.4 × 10−20 cm−2 for 240 eV ion bombardment. The increased nucleation rate for vacancies is attributed to clustering of defects. The sputtering yield of Ge(001) is also measured by STM. The sputtering yield for 20 eV ions is approximately 10−3 per ion but the net yield for surface defects (sum of adatoms and vacancies) is an order of magnitude higher, 10−2, due to adatom-vacancy pair creation. 相似文献
990.
Summary The separation of C1–C4 mononitroalkanes on four wall-coated glass open tubular (capillary) columns (liquid phases: OV-101, Ucon-LB-550X, NPGS and Carbowax 20M) was investigated. Retention indices were determined and the influence of the different factors (analysis temperature, method of determining the gas holdup time and the nature of the stationary phases) on their reproducibility were studied. Linear regression equations permit the pre-calculation of the retention indices of C1–C4 mononitroalkanes from their properties on all liquid phases studied. 相似文献