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101.
102.
介绍利用AutoCAD Civil 3D进行道路建模的过程,并将Civil 3D道路模型导入到3ds Max Design中作进一步加工,从而进一步获取道路的三维景观模型. 相似文献
103.
Fine assessment of tropical cyclone disasters based on GIS and SVM in Zhejiang Province, China 总被引:1,自引:1,他引:0
Tropical cyclones represent major natural disasters in low- and mid-latitude coastal areas. Effective assessment of tropical cyclone disasters provides a scientific reference for the formulation of tropical cyclone prevention and disaster-relief measures. Tropical cyclone disasters in Zhejiang Province are mainly studied based on GIS technology, by considering disaster-causing factors, disaster-affected bodies, the disaster-formative environment, and spatial distribution of disaster prevention and relief capacity. In light of an uncertain nonlinear relationship between assessment factors and disaster factors, we used support vector machines to establish a fine, quantitative assessment model. This model evaluates the following disaster indices: Disaster-affected population, direct economic loss, affected crop area, and number of damaged houses resulting from a tropical cyclone disaster in Zhejiang, with the county as basic assessment unit. Assessment of tropical cyclone No. 0908 shows that the developed assessment model is able to accurately evaluate the geographical distribution of losses caused by a tropical cyclone. 相似文献
104.
Tropical cyclones are the most common natural disasters in coastal regions and are the most costly in terms of economic losses.
Economic loss assessment is the basis for disaster prevention and alleviation and for insurance indemnification. We use data
from 1970 to 2008 for Zhejiang Province, China, in this study evaluating economic losses. We convert direct economic losses
from tropical cyclone disasters in Zhejiang Province into indices of direct economic losses. To establish our assessment model,
we process disaster-inducing assessment factors, disaster-formative environments and disaster-affected bodies using the principal
component analysis method, and we abstract the principal component as the input of a BP neural network model. We found in
the actual assessments of five tropical cyclones affecting Zhejiang Province in 2007 and 2008 that the post-disaster loss
assessment values of tropical cyclones were higher than the actual losses, but that for more severe storms, the gap was smaller.
This reflects the beneficial effect of efforts toward disaster prevention and alleviation for severe tropical cyclones. Pre-assessments
based on relatively accurate forecast values of wind and precipitation at the start of a tropical cyclone have been in accordance
with the post-disaster assessment values, while the pre-assessment results using less accurate forecast values have been unsatisfactory.
Therefore, this model can be applied in the actual assessment of direct economic loss from tropical cyclone damage, but increasingly
accurate forecasting of wind and precipitation remains crucial to improving the accuracy of pre-assessments. 相似文献
105.
Pei Sun Loh Chen-Tung Arthur ChenGusti Z. Anshari Jough-Tai WangJiann-Yuh Lou Shu-Lun Wang 《Journal of Asian Earth Sciences》2012,43(1):118-129
In this first study of lignin geochemistry in the world’s longest river on an island, surface sediments were collected along the Kapuas River, three lakes in the upper river, a tributary in the lower river and a separate river during June-July 2007 and December 2007-January 2008. The samples were analyzed for lignin-derived phenols and bulk elemental and stable carbon isotope compositions. Λ values (the sum of eight lignin phenols, expressed as mg/100 mg organic carbon (OC)) ranged from 0.13 to 3.70. Ratios of syringyl/vanillyl (S/V) and cinnamyl/vanillyl (C/V) ranged from 0.34 to 1.18 and 0.28 to 1.40, respectively, indicating the presence of non-woody angiosperm tissues. The high vanillic acid to vanillin (Ad/Al)v (0.71-2.01) and syringic acid to syringaldehyde (Ad/Al)s (0.72-2.12) ratios indicate highly degraded lignin materials. In the upper Kapuas River, highly degraded soil materials discharged from lands that were barren as a result of deforestation activities were detected in the locations directly in those vicinities. The middle Kapuas River showed rapid organic matter degradation, probably due to the presence of fresh terrestrial and phytoplankton organic matter fueling the biogeochemical cycling. The Kapuas Kecil River, one of the two branches in the lower reach of the Kapuas River, showed higher levels and diagenesis of sedimentary organic matter due to input from anthropogenic sources and increased marine organic matter near the mouth. This study shows that different stretches along the river exhibit different levels and composition of sedimentary organic matter, as well as different carbon dynamics, which is directly attributable to the varying landscapes and quality of organic matter. 相似文献
106.
107.
Jay Parker Gregory Lyzenga Charles Norton Cinzia Zuffada Margaret Glasscoe John Lou Andrea Donnellan 《Pure and Applied Geophysics》2008,165(3-4):497-521
GeoFEST (Geophysical Finite Element Simulation Tool) is a two- and three-dimensional finite element software package for the modeling of solid stress and strain in geophysical and other continuum domain applications. It is one of the featured high-performance applications of the NASA QuakeSim project. The program is targeted to be compiled and run on UNIX systems, and is running on diverse systems including sequential and message-passing parallel systems. Solution to the elliptical partial differential equations is obtained by finite element basis sampling, resulting in a sparse linear system primarily solved by conjugate gradient iteration to a tolerance level; on sequential systems a Crout factorization for the direct inversion of the linear system is also supported. The physics models supported include isotropic linear elasticity and both Newtonian and power-law viscoelasticity, via implicit quasi-static time stepping. In addition to triangular, quadrilateral, tetrahedral and hexahedral continuum elements, GeoFEST supports split-node faulting, body forces, and surface tractions. This software and related mesh refinement strategies have been validated on a variety of test cases with rigorous comparison to analytical solutions. These include a box-shaped domain with imposed motion on one surface, a pair of strike slip faults in stepover arrangement, and two community-agreed benchmark cases: a strike slip fault in an enclosing box, and a quarter-domain circular fault problem. Scientific applications of the code include the modeling of static and transient co- and post-seismic earth deformation, Earth response to glacial, atmospheric and hydrological loading, and other scenarios involving the bulk deformation of geologic media. 相似文献
108.
109.
针对三维规划审批对精确的空间关系及逼真的三维可视化效果的综合需求,设计实现了两套针对大规模三维数字城市建筑物模型的屋顶纹理快速生成方案。方案一基于严格投影成像方程建立物方与像方对应关系,并根据视线方向、遮挡关系、成像分辨率等选取最优纹理进行映射。方案二通过建立相应的屋顶纹理库,并利用屋顶纹理智能匹配技术实现大范围屋顶纹理的快速合成。利用常州市三维城市模型数据进行了实验分析,实验表明,这两套纹理生成方案生成的屋顶纹理都满足建筑物纹理重建生产要求,极大地提高了三维建模效率。 相似文献
110.
渤海、黄海是高产二甲基硫(Dimethyl Sulfide, DMS)的大陆架海区。该海区DMS的现场调查研究有助于准确评估海洋DMS释放量及其对全球气候变化的负反馈作用。目前,无论是基于模型还是直接测量法的通量估算均以表层海水或低层大气DMS浓度为基础,因此,先进的检测技术对其通量估算的准确度具有决定性作用。气相色谱法、质谱法、化学发光法以及卫星遥感技术是现在常用的观测技术,而本文则基于苯辅助光电离离子迁移谱技术进一步提出了一种可在海域现场观测海水中DMS的方法。通过结合动态气提-Nafion管在线除水进样系统,消除环境水汽的干扰;在最优条件下,基于DMS两个产物离子峰,可以实现0.10~120 nmol/L之间DMS的定量分析,检测限低至0.065 nmol/L;然后将所建方法应用于2019年秋季渤海、北黄海海水中DMS的现场观测。结果表明,表层海水中DMS的浓度为0.080~0.96 nmol/L(平均值为(0.44±0.34)nmol/L),其海气通量为0.12~17.75 μmol/(m2·d)(平均值为( 3.23±4.02)μmol/(m2·d));通过结合实验室检测结果、环境因子和浮游植物群落结构讨论了海水样品低温储存条件下DMS的变化和影响因素,结果显示,营养盐成分及浮游植物群落结构是影响储存样品中DMS浓度显著增加的主要因素,进一步表明了现场观测方法的建立对海洋DMS释放量的准确评估具有重要意义。 相似文献