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31.
大破裂限定了托卡马克的运行。实验指出,撕裂模或者说磁岛的发展是这种大破裂的主要原因。考虑到无感电流驱动效应,我们重新推导了电阻撕裂模的三维非线性方程组?数值计算表明,跟随磁岛旋转的RF波电流驱动有效地抑制磁岛的发展。 相似文献
32.
Zhenyang Zhong Gang Chen J. Stangl Th. Fromherz F. Schffler G. Bauer 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):588
Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned Si (0 0 1) substrates. The sample topography, obtained by atomic force microscopy, exhibits a regular two-dimensional island arrangement. The vertical alignment is confirmed in cross-sectional transmission electron microscopy images. X-ray diffraction reciprocal space maps around the (0 0 4) Bragg point reveal exceptional lateral and vertical ordering of the Ge islands. Photoluminescence spectra taken at 5 K show well-separated peaks of the no-phonon and the transverse-optical phonon replica of these ordered islands, which is achieved too, due to the excellent island size uniformity. 相似文献
33.
Growth behavior of thin Ag films on Si substrates at room temperature has been investigated by scanning tunneling microscopy and reflection high energy electron diffraction. In the layer-plus-island growth Ag islands show strongly preferred atomic scale heights and flat top. At low coverage (1 ML), islands containing two atomic layers of Ag are overwhelmingly formed. At higher coverages island height distribution shows strong peaks at relative heights corresponding to an even number (2, 4, 6, …) of Ag atomic layers. Beyond some coverage the height preference vanishes due to the appearance of screw dislocations and spiral growth. 相似文献
34.
We consider two-parameter families of C
r-smooth, r6, two-dimensional area-preserving diffeomorphisms that have structurally unstable simplest heteroclinic cycles. We find the conditions when diffeomorphisms under consideration possess infinitely many periodic generic elliptic points and elliptic islands. 相似文献
35.
采用实际的生长模型和物理参量,用Monte Carlo方法对高温下金属薄膜的生长过程进行了模拟研究.综合考虑了原子沉积、扩散、成核、生长和扩散原子的再蒸发、原子沿岛周界扩散和岛的合并等众多过程后,模拟得到与实验结果相当一致的薄膜生长形貌及其相应的定量结果.通过动态统计薄膜生长过程中的岛数目及薄膜生长率,得到实验中不易直接获得的高温下薄膜生长的许多细节,如岛数目和薄膜生长率随表面温度、覆盖度变化的详细情况等
关键词:
薄膜
Monte Carlo模拟
成核
岛密度
薄膜生长率 相似文献
36.
随着全球气候变暖、城市化进程加快,世界各地大城市的“热岛”效应及其带来的各种环境和生态问题越来越严重。本文从地质环境保护的角度,分析了城市“热岛”效应的成因、特点及其对地质环境的影响,重点讨论了城市“热岛”效应环境中土体工程性质的变化及其带来的各种灾害效应,在此基础上,凝练出了4个关键科学问题,即城市“热岛”效应环境中土体温度场变化规律、土体中水分迁移规律、土体工程性质变化规律以及土体地质灾害效应,并对它们的具体研究内容进行了详细的分析。论文的分析成果对于掌握城市“热岛”效应对土体工程性质的影响,保护城市地质环境和防灾减灾,实现城市的可持续发展具有重要的理论和现实意义。
相似文献
相似文献
37.
We present two‐dimensional numerical simulations of a natural convection problem in an unbounded domain. The flow circulation is induced by a heat island located on the ground and thermal stratification is applied in the vertical direction. The main effect of this stably stratified environment is to induce the propagation of thermal perturbations in the horizontal direction far from the local thermal source. Numerical stationary solutions at Ra?105 are computed in large elongated computational domains: convergence with respect to the domain sizes is investigated at different resolutions. On fine grids, with mesh size , a thermal sponge layer is added at the vertical boundaries: this local damping technique improves the convergence with respect to the domain length. Boussinesq equations are discretized with a second‐order finite volume scheme on a staggered grid combined with a second‐order projection method for the time integration. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
38.
39.
Concentrations of 10 Be were measured in 23 lava samples representing historically and 14C dated eruptions of major Kurile and Kamchatka volcanoes. We report 2.2–7.9 · 106 at/g of 10Be for Kuriles and in most cases less than 1.2 · 106 at/g for Kamchatka. Thus Kurile segment of the Kurile-Kamchatka arc system features the same isotopic pattern as the Aleutians and some continental arcs like Central America and the Andes. The obtained results confirm previously drawn conclusion that the scale of sediment incorporation in Kurile magmas is not large thought the process itself is quite real. 相似文献
40.
黄森 《中国科学B辑(英文版)》1990,(11)
The characteristics of the nigrostriatal dopaminergic neuroconnections in developing rats are studied by combined immunocytochemical and electron-microscopic techniques, with an antibody to tyrosine hydroxylase (TH). From the embryonic day 21 on, some of the THpositive nerve fibers are densely packed in the striatum to form a patch-like dopamine island. The percentage of the TH-positive nerve terminals among the labeled profiles is much higher inside than outside the dopamine island (P<0.01). On the other hand, the TH-positive terminals mainly form symmetrical axon-dendritic synapses, while most of the TH-negative terminals form asymmetrical axon-spinous synapses. The functional significance of the characterized dopaminergic connection is discussed. 相似文献