Hydrogen adsorption and diffusion on amorphous solid water ice     

A. Al-Halabi  E. F. van Dishoeck † 《Monthly notices of the Royal Astronomical Society》2007,382(4):1648-1656

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The H i content of elliptical and lenticular galaxies withrecent star formation     

J. F. Helmboldt 《Monthly notices of the Royal Astronomical Society》2007,379(3):1227-1236

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Constraints on unstable heavy neutrinos from cosmology     

M. M. Vasanthi  T. Padmanabhan 《Journal of Astrophysics and Astronomy》1986,7(2):59-70

Cosmological scenarios with massive unstable neutrinos are discussed. Restrictions on the mass and the lifetime of the unstable neutrino are derived from (a) age and mass density of the universe and (b) the growth of primordial fluctuations. It will not be possible to accommodate unstable neutrinos with masses above ∼ 1 ke V in standard cosmology unless they have exceedingly small lifetime: Τ <5 × 10⁸ s.  相似文献   

月面形貌的3维可视化算法   总被引：1，自引：0，他引：1  

周杨  徐青  康宁  张勇 《测绘学报》2009,38(6)

基于大范围地形可视化算法研究的基础上,对平面geometry clipmaps算法进行改进,利用GPU的顶点着色器实现平面地形向球面地形的投影变换,并综合利用球面视域裁剪、球面视点控制等技术,使geometry clipmaps算法适用于球面海量地形数据的3维可视化;收集处理月球全球影像和形貌高程数据,对算法进行验证,实现月球表面形貌的实时动态3维可视化.试验表明:绘制算法可不受数据量大小的限制、绘制效率高、效果逼真,但存在两极变形较大的缺点.

Abstract：

Based on the study of visualization arithmetic of large area terrain, plane geometry clipmaps algorithm is improved. Projection transformation from plane landform to sphere landform was realized by using GPU vertex shader. In that improved algorithm, methods such as sphere vision field culling and sphere viewpoint control are used.That makes geometry clipmops algorithm more effective in 3D visualization of massive sphere terrain data. The whole moon image and DEM data are collected and disposed, which are used to verify the capability of that algorithm, realizing dynamic and real time 3D visualization of moon surface. The experiments show that the graphic algorithm isn't limited by data quantity, which is of high efficiency and reality simulation, but the two-pole distortion is serious.  相似文献   

Additional effects of resonance in Hilda-asteroid orbits by the combined action of Jupiter and Saturn     

J. Schubart 《Icarus》2007,188(1):189-194

Inside the 3/2 mean motion resonance some Hilda-type orbits show effects of a three-body resonance that includes the frequency of the libration due to the 3/2 resonance. A graphical method presents numerical results for such orbits and demonstrates in 6 cases a process of temporary libration, that is ruled by the additional resonance together with the secular period of the eccentricities of Jupiter and Saturn.  相似文献   

A comparative analysis of metiers and catch profiles for some French demersal and pelagic fleets     

Marchal  Paul 《ICES Journal of Marine Science》2008,65(4):674-686

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弱流场调制下的海面微波散射模拟研究          下载免费PDF全文

吕伟艳  赵朝方  杜涛 《海洋科学》2008,32(7):57-61

根据海面微波散射的多尺度模型以及波流相互作用理论，对一维弱流场调制下的海面微波散射截面进行了数值模拟。结果表明，利用数值方法直接求解波作用量方程获得的海浪调制谱并结合多尺度模型可以较好地模拟弱流场引起的雷达散射截面的变化。内波等海洋现象调制了海浪谱，使得雷达散射截面反映出这些海洋特征，整个调制过程的模拟对于分析这些海洋现象并更好地利用其雷达数据具有重要意义。  相似文献   

Multidimensional treatment of photon emission from accretion discs around black holes     

Kazunori Kohri  Ken Ohsuga  Ramesh Narayan 《Monthly notices of the Royal Astronomical Society》2007,381(3):1267-1274

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Structure and clumping in the fast wind of NGC 6543     

R. K. Prinja  S. E. Hodges  D. L. Massa  A. W. Fullerton  A. W. Burnley 《Monthly notices of the Royal Astronomical Society》2007,382(1):299-307

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Particle distributions and X-ray spectra in single or multiple solar current sheets     

C. Gontikakis  A. Anastasiadis  C. Efthymiopoulos 《Monthly notices of the Royal Astronomical Society》2007,378(3):1019-1030

The acceleration of charged particles in a site of magnetic reconnection is analysed by detailed numerical simulations. Single or multiple encounters of the particles with Harris-type reconnecting current sheets (RCSs) are modelled as an overall stochastic process taking place within an active region. RCS physical parameters are selected in a parameter space relevant to solar flares. Initially, the charged particles form a thermal (Maxwellian) distribution corresponding to coronal temperature  ≃2 × 10⁶ K  . Our main goal is to investigate how the acceleration process changes the shape of the particles' kinetic energy distribution. The evolution of the kinetic energy distribution, calculated numerically after one encounter of the particles with a single RCS, is found to be in good agreement with our previously published analytical formulae. In the case of consecutive encounters, we find that the kinetic distribution tends to converge to a practically invariant form after a relatively small number of encounters. We construct a discrete stochastic process that reproduces the numerical distributions and we provide a theoretical interpretation of the asymptotic convergence of the energy distribution. We finally compute the theoretical X-ray spectra that would be emitted by the simulated particles in a thick target model of radiation.  相似文献