Interactive Design of 3D Maps with Progressive Projection     

《The Cartographic journal》2013,50(3):211-221

Abstract

The progressive projection is by origin a manual cartographic technique, traditionally used by panoramic landscape painters; however, it is rarely encountered in digitally created three-dimensional (3D) maps. In this article, the advantages of this specific projection when designing 3D maps are presented, the processes involved in its manual construction, as well as the existing and potential digital implementation approaches, are reviewed. A new algorithmic solution is described, allowing for user-friendly interactive bending of a terrain model into a progressive view, with options to add a curved horizon, to vertically exaggerate the terrain, and to create a 360° strip panorama. The resulting software, Terrain Bender, is freely available for download.  相似文献   

含微生物气泡高饱和砂土循环三轴剪切CFD-DEM模拟          下载免费PDF全文

蒋明镜  沈振义  刘俊  杨涛  谭亚飞鸥 《地震工程学报》2021,43(2):353-360

为探究砂土液化的微观机理,根据室内试验中微生物反硝化反应气泡的生成速率,建立数值模拟的时效性关系,分别制取微生物处理0天、2天、3天和5天的高饱和砂土试样,采用CFD-DEM耦合方法模拟不同工况下砂土试样的循环三轴不排水剪切试验。依据砂土试样的力链分布、抗液化振次、孔压比、轴向应变和力学配位数在加载过程中的变化情况,从宏微观角度分析砂土试样的抗液化能力。模拟结果表明:含微生物气泡高饱和砂土的抗液化强度较饱和砂土有所提升;随着微生物处理时间的增加,砂土试样的饱和度降低,孔压比和轴向应变的累积变慢,抗液化能力增强。  相似文献   

Numerical modeling of heterogeneous flow fields around rigid objects with special reference to particle paths, strain shadows and foliation drag   总被引：2，自引：0，他引：2  

N. Mandal  S. K. Samanta  C. Chakraborty   《Tectonophysics》2001,330(3-4):177-194

With the help of two-dimensional numerical models this paper investigates three aspects of heterogeneous deformation around rigid objects: (1) the nature of particle paths; (2) the development of strain shadow zones; and (3) the drag patterns of passive markers. In simple shear, spherical objects develop typically a concentric vortex motion, showing particle paths with an eye (double-bulge)-shaped separatrix. The separatrix has no finite dimension along the central line, parallel to the shear direction. Under a combination of pure shear and simple shear, the particle paths assume a pattern with a bow-tie shaped separatrix. With increase in the ratio of pure shear to simple shear (S_r), the separatrix around the object shrinks in size. The axial ratio of the object (R) is another important factor that controls the geometry of particle paths. When R<1.5, the loci of a particle close to the object form an elliptical shell with the long axis lying along the central line. With increase in axial ratio R, the loci form a doublet elliptical shell structure. Objects with R>3 do not show closed particle paths, but give rise to elliptical or circular spiral particle paths.

The development of strain shadow zones against equant rigid bodies depends strongly on the strain ratio S_r. When S_r=0 (simple shear), they develop opposite to the extensional faces of the object, forming a typical σ-type tail. The structure has a tendency to die out with an increase in the pure shear component of the bulk deformation (S_r). The initial angle of the long axis of the object with the shear direction (φ) and the axial ratio of the object (R) determine the development of strain shadow zones near inequant rigid objects. Objects with large R and φ between 60 and 120° form pronounced zones of low finite strain, giving rise to strain shadow structures. A geometrical classification of diverse drag patterns of passive markers around rigid objects is presented along with their conditions of formation.  相似文献   

Finite element modelling of thick plates on two‐parameter elastic foundation     

Ryszard Buczkowski  Witold Torbacki 《国际地质力学数值与分析法杂志》2001,25(14):1409-1427

This paper is intended to give some information about how to build a model necessary for bending analysis of rectangular and circular plates resting on a two‐parameter elastic foundation, subjected to combined loading and permitting various types of boundary conditions. The formulation of the problem takes into account the shear deformation of the plate and the surrounding interaction effect outside the plate. The numerical model based on an 18‐node zero‐thickness isoparametric interface element interacting with a thick Reissner–Mindlin plate element with three degrees of freedom at each of the nine nodes, which enforce C⁰ continuity requirements for the displacements and rotations of the midsurface, is proposed. Stiffness matrices of a special interface element are superimposed on the global stiffness matrix to represent the stiffening elastic foundation under and beyond the plate. Some numerical examples are given to illustrate the advantages of the method presented. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Bending instability of stellar disks: The stabilizing effect of a compact bulge     

N. Ya. Sotnikova  S. A. Rodionov 《Astronomy Letters》2005,31(1):15-29

The saturation conditions for bending modes in inhomogeneous thin stellar disks that follow from an analysis of the dispersion relation are compared with those derived from N-body simulations. In the central regions of inhomogeneous disks, the reserve of disk strength against the growth of bending instability is smaller than that for a homogeneous layer. The spheroidal component (a dark halo, a bulge) is shown to have a stabilizing effect. The latter turns out to depend not only on the total mass of the spherical component, but also on the degree of mass concentration toward the center. We conclude that the presence of a compact (not necessarily massive) bulge in spiral galaxies may prove to be enough to suppress the bending perturbations that increase the disk thickness. This conclusion is corroborated by our N-body simulations in which we simulated the evolution of near-equilibrium, but unstable finite-thickness disks in the presence of spheroidal components. The final disk thickness at the same total mass of the spherical component (dark halo + bulge) was found to be much smaller than that in the simulations where a concentrated bulge is present.  相似文献   

Palaeomagnetic evidence and tectonic origin of clockwise rotations in the Yangtze fold belt, South China Block   总被引：6，自引：0，他引：6  

Xiaodong Tan  Kenneth P. Kodama  Stuart Gilder  Vincent Courtillot  Jean-Pascal Cogné 《Geophysical Journal International》2007,168(1):48-58

  相似文献   

陆上纵波源VSP资料中的纯横波     

刘洋  张庆红  鲍磊英  魏修成 《应用地球物理》2007,4(3):173-182

常规陆上VSP(Vertical Seismic Profiling)勘探普遍采用纵波震源激发,三分量检波器接收,主要利用的是纵波和转换横波信息。已有的研究表明,炸药震源在井下激发、可控震源在地面垂向振动,均会产生较强的纯纵波和一定强度的纯横波;泊松比差别较大的分界面有利于形成较强的透射转换横波。本文通过对激发形成的纯横波和下行转换形成的横波进行对比分析,认为纯横波的主频往往低于纯纵波的主频,而下行转换横波的主频通常接近纵波的主频。本文分别对两个陆上纵波源零偏和非零偏VSP资料进行分析,结果表明这些资料中普遍存在纯横波,只是横波的强弱存在不同程度的变化。利用纵波源零偏VSP资料,可以获得横波速度信。最后对VSP纵波和横波联合应用前景进行了分析,应该充分利用纵波源VSP资料中的横波信息。  相似文献   

用能量法研究深直井管柱最大转速与正弦屈曲时临界轴向力间的关系          下载免费PDF全文

陈敏  吕建国  刘宝林  肖天鹏 《探矿工程》2005,32(12):40-42

通过考虑离心力对钻柱屈曲的影响，运用能量法研究了钻柱最大转速与正弦屈曲时临界轴向力间的关系，进而得到了转速－轴向临界力的数学模型。综合考虑钻柱惯性离心力和自重的影响，我们发现，在工作状态下，钻柱的临界压力会明显地小于静态时的临界力，这对实际的钻探工程来说具有十分重要的指导意义。  相似文献   

改进的Theis井流模型及其解析解——考虑含水层顶板的挠曲作用     

旭升  陈崇希 《地球科学》2002,27(2):199-202

传统承压含水层井流理论都假定承压水层顶面总应力不变，其隐含的意义是忽略含水层顶板的刚度，从而忽略了顶板弯曲对含水层释水的影响。指出考虑顶板弯曲时，抽水井周围承压含水层顶部的总应力将减小，从而产生比传统理论估计更大的地下水降深，并结合弹性板理论对Theis井流模型作出了改进，新模型的解析解证明Theis模型计算的地下水龙头降深偏低。  相似文献   

当前矿泉水界需要重视的几个问题     

何京生 《四川地质学报》1997,(1)

判别真假矿泉水的主要责任应该在行政主管部门和执法管理部门，矿泉水应具备国家标准中指列的要求。瓶装矿泉水“宜冷藏不宜冷冻”，冷冻出现沉淀也无土方。矿泉水不存在“有害元素含量的抑制”问题，偏离规定的矿泉水开发是非法的。纯净水应有准确的定义或含义，目前市场上的纯净水具有可变性，“纯净”的跨度很大，名称繁多，商家的广告缺乏科学性，使人莫明其解，瓶装水都应在平等条件下竞争，行政主管部门应加强管理。  相似文献