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91.
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   
92.
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   
93.
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   
94.
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   
95.
安徽铜陵狮子山矿田铜、金共生与分离的热力学研究   总被引:4,自引:0,他引:4  
狮子山矿田是安徽铜陵矿集区内最具代表性的大型铜金多金属矿田.矿田内铜、金矿床或矿体既各自独立产出,义相互共生或伴生,铜矿化和金矿化在时间上和空间上存在既共生又分离的现象.本文选择矿田内代表性铜矿床和金矿床开展系统的流体包裹体地球化学研究,并进行成矿流体中铜、金溶解度的热力学理论计算和1分析,探索铜、金共生与分离的机制和...  相似文献   
96.
本文以日本神户市地铁大开站为工程背景,应用大型通用有限元ANSYS软件,分别建立了自然条件下的工程场地土层和建有地下车站结构的土层的二维有限元分析模型。计算了基岩一致地震动输入模式下2个土层模型的动力反应。通过将2个土层模型的动力反应进行比较分析,讨论了地下结构对工程场地地震动场的影响。分析结果表明,日本神户地铁大开站的存在对其邻近区域土层的地震反应有影响,但影响有限。  相似文献   
97.
Differential synthetic aperture radar interferometry (D-InSAR) has become a useful technique for monitoring ground movement. The technique enables the analysis of very small ground movements in continuous, large areas and has the advantages of high accuracy, high resolution, all-weather adaptability, low cost, and inaccessible area coverage. Thus, D-InSAR has been widely used in the investigation of geologic hazards, such as subsidence, landslide, earthquake, and volcanic activity. In this paper, D-InSAR is used to locate and monitor landslide movement in the wide area of Wudongde Hydropower Reservoir in Jinsha River, China. Five SAR acquisitions are obtained by using the phased array-type L-band synthetic aperture radar sensor of the Advanced Land Observing Satellite. Detailed moving displacement maps in two time periods are derived by using the D-InSAR technique, and potentially moving landslide areas, as well as landslide hazard areas, are then located. The L1R-6 landslide, which is in active state, is investigated in detail. The deforming tendency obtained via D-InSAR is consistent with that obtained via global positioning system (GPS) monitoring. Error analysis of the D-InSAR results is also conducted. Finally, the grid function interpolation method of error reduction, which combines D-InSAR and GPS, is proposed to reduce the single-point error in D-InSAR monitoring and is further verified by the considerable improvement in the accuracy of L1R-6 landslide monitoring.  相似文献   
98.
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   
99.
本文以某一大型直流电压发生器塔架结构为例,建立有限元计算模型,采用调幅正弦五波、Taft地震波、El-Centro地震波、云南澜沧地震波和正弦三波5种地震动输入,通过数值计算,讨论了不同输入地震波对于结构抗震设计的影响。结果表明,地震作用效应在这类特种结构的组合响应中起重要影响,采用调幅正弦五波、正弦三波作为地震输入,过分夸大了实际的地震作用效应。最后,对这类特种结构的输入地震动提出了相应建议。  相似文献   
100.
河南商城—固始地区石炭系沉积环境及其构造意义   总被引:13,自引:0,他引:13  
赵宗举  杨树锋 《地质论评》2000,46(4):407-416
根据沉积相分析,同时综合分析区域地质资料,笔者提出河南商城-固始地区石炭系及安徽金寨地区梅山群为典型前陆磨拉石含煤建造,其沉积相主要为滨海、潮坪、泻湖、局限台地及砾质辫状河-冲积扇相,代表了统一的石炭纪一二叠纪合肥弧后前陆盆地的南部边缘相,说明大别地块(北大别弧)于早古生代晚期-晚古生代早期即与华北板块碰扪结成一体。  相似文献   
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