An excursion set model for the distribution of dark matter and dark matter haloes

A model of the gravitationally evolved dark matter distribution, in the Eulerian space, is developed. It is a simple extension of the excursion set model that is commonly used to estimate the mass function of collapsed dark matter haloes. In addition to describing the evolution of the Eulerian space distribution of the haloes, the model allows one to describe the evolution of the dark matter itself. It can also be used to describe density profiles, on scales larger than the virial radius of these haloes, and to quantify the way in which matter flows in and out of Eulerian cells. When the initial Lagrangian space distribution is white noise Gaussian, the model suggests that the Inverse Gaussian distribution should provide a reasonably good approximation to the evolved Eulerian density field, in agreement with numerical simulations. Application of this model to clustering from more general Gaussian initial conditions is discussed at the end.     

Testing the nonsysmmetric gravitational theory with rotation curves of galaxies

We use the rotation curves of 13 galaxies to test the nonsymmetric gravitaional theory (NGT). If we follow Moffat's assumption of a constant mass-to-light for all galaxies then we shall find that the two supposedly universal constants r₀, L₀ to show a large scatter. By regarding the mass-to-light ratio as a free parameter for each galaxy, and adjusting the values of r₀, L₀, we find that NGT can well account for the observed rotation curves. Further, the mass-to-light ratios so found show the well-known trend along the Hubble morphological sequence.     

Study on the fractal character of magnetic anomaly fields and the delineation of tectonic elements in the South China Sea

INTRODUCTION~hon0ffornjcelmtSwnthebasisofthestudyonthecrustaldefonnationanddeVel0prnent,thedistributionofndnereIs,andthendnerogeneticlawr.ThegeornagneticfieklisthecomP0siterefledionoftheformati0nanddefortnationofthecrust.Sornagnct-icsLLrVeydatacomPriseirnPortantbasisfordelincatingthearchiteCtonicelements,dCtendningtheirboundarylines,andanalopngthesanndarystrudriineachelernent,whicharetthernaintasks0fgoophySicalworkers.Thegoornagneticdelineati0nofanareahadforlongbodonequalitativeybyobs…     

用等效球Mie理论计算冰云光学特性的一种新方法

对由六角形冰晶粒子组成的冰云的１４种冰晶尺度分布,分别用等效球Ｍｉｅ理论和射线光学理论计算了它们在从可见光到近红外谱区的１７个波长上的散射特性参量。并利用由等效球Ｍｉｅ理论获得的散射参数及冰晶尺度分布特征参量ｒｅ（有效半径）建立了冰云光学特性的参数化公式。这些参数化公式的最大相对误差小于５％。     

山区资源开发的互补转换理论

通过从结构与功能上对山区资源进行重新分类及相对优劣势分析,提出了合理开发山区资源的“山区资源开发互补转换理论”.     

Quasi-isotropic approximation of ray theory for anisotropic media

Wave propagation in weakly anisotropic inhomogeneous media is studied by the quasi-isotropic approximation of ray theory. The approach is based on the ray-tracing and dynamic ray-tracing differential equations for an isotropic background medium. In addition, it requires the integration of a system of two complex coupled differential equations along the isotropic ray.
The interference of the qS waves is described by traveltime and polarization corrections of interacting isotropic S waves. For qP waves the approach leads to a correction of the traveltime of the P wave in the isotropic background medium.
Seismograms and particle-motion diagrams obtained from numerical computations are presented for models with different strengths of anisotropy.
The equivalence of the quasi-isotropic approximation and the quasi-shear-wave coupling theory is demonstrated. The quasi-isotropic approximation allows for a consideration of the limit from weak anisotropy to isotropy, especially in the case of qS waves, where the usual ray theory for anisotropic media fails.     

构建旅游中心城市之研究——以荆门市为例

在探讨旅游中心城市概念、地位及作用的基础上，以荆门市为例，分析了荆门市旅游产业发展中存在的问题、研究了荆门市建设为区域旅游中心城市的条件和优势，包括较为发达的城市经济、丰富的资源、良好的区位、科学的规划、完善的设施等，并借用中心地理论来说明荆门市应该成为区域旅游中心城市，最后列出了具体思路。     

Spatial dynamics of retail structure and the venerable retail hierarchy

The retail system is continuously adapting itself to changing demographic conditions, consumer behavior and economic conditions. Existing retail units, getting larger in order to achieve economics of scale, and new forms of large-scale retailing do not fit easily in the traditional spatial pattern of retail concentrations. Neverteless the spatial distribution of retailing in urban areas, as schematized by Berry thirty-five years ago, still has its value. Through an upward hierarchical movement the retail system has adapted itself to an inflexible spatial system, in which downtown has still a dominant position. Future developments, however, may weaken the position of central shopping areas in favour of peripheral locations. This revised version was published online in July 2006 with corrections to the Cover Date.