顾及三角形处理的TIN建立算法   总被引：6，自引：1，他引：6  

陈仁喜  龙毅 《武汉大学学报(信息科学版)》2003,28(5):619-622

提出了一种基于相邻等高线的TIN建立算法——区域分割构网算法，并阐述了其基本思想。通过对山顶、鞍部和山谷(山脊)不同地貌区域的试验，证实了该方法的有效性。  相似文献   

北疆500年干湿变化特征   总被引：26，自引：7，他引：26  

袁玉江  韩淑Ti 《冰川冻土》1991,13(4):315-322

  相似文献   

田庄等测点周围的磁场梯度测量   总被引：2，自引：2，他引：2  

赵从利  詹志佳 《地震地磁观测与研究》1994,15(3):28-31,20

磁场梯度测量是选建地磁测点过程中的一项重要工作。在田庄、灵山、东兴庄测点周围，进行了磁场梯度的一般测量与详细测量，结果显示，各测桩的水平方向与垂直方向的磁场梯度均不大于１．０ｎＴ／ｍ。完全符合磁测规范的要求。  相似文献   

A quantitative morphometric comparison of cockpit and doline karst landforms   总被引：1，自引：0，他引：1  

Fuyuan Liang  Yunyan Du  Yong Ge  Ce Li 《地理学报(英文版)》2014,24(6):1069-1082

This study presented a quantitative comparison of cockpit and doline karst by examining the numbers and characteristics of typical types of landform entities that are developed in Guilin（Guangxi, China）, La Alianza（PR, USA）, Avalton（KY, USA）, and Oolitic（IN, USA）. Five types of landform entities were defined： isolated hill（IH）, clustered hills（CHs）, isolated sinkhole（IS）, clustered sinkholes（CSs）, and clustered hills with sinkholes（CHSs）. An algorithm was developed to automatically identify these types of landform entities by examining the contour lines on topographic maps of two cockpit karst areas（Guilin and La Alianza） and two doline karst areas（Oolitic and Avalton）. Within each specific study area, the CHSs is the least developed type yet with a larger size and higher relief. The IH and IS entities are smaller in size, lower in relief, and outnumber their clustered counterparts. The total numbers of these types of entities are quite different in cockpit and doline karst areas. Doline karst is characterized by more negative（IS and CSs） than positive（IH and IHs） landforms and vice versa for cockpit karst. For example, the Guilin study area has 1192 positive landform entities in total, which occupy 9.81% of the total study area. It has only 622 negative landform entities occupying only 3.91% of the total study area. By contrast, the doline karst in Oolitic has 130 negative while only 10 positive landform entities. The positive and negative landforms in Oolitic occupy 12.68% and 2.61% of the total study area, respectively. Furthermore, average relief and slope of the landform entities are much higher and steeper in the cockpit karst than the doline karst areas. For instance, the average slope of CHs in Alvaton is 3.90 degrees while it is 19.78 degrees in La Alianza. The average relief of CSs is 4.07 m and 34.29 m in Oolitic and Guilin respectively. Such a difference within a specific area or between the cockpit and doline karst may reveal different controls on  相似文献   

一种利用坡度分区滤波的DEM转换等高线方法     

赵学松  吴君峰 《测绘通报》2017,(3):120-123

针对DEM转换等高线时,现有方法不能方便、有效处理好曲线光滑与地貌精度损失之间的关系,提出了基于坡度分区滤波的DEM转换等高线方法。对不同的坡度分区采用不同大小的窗口进行均值滤波,并对滤波高程差值进行控制,较好地处理了曲线光滑与地貌精度损失之间的关系;同时,对计曲线之间的窄部首曲线进行自动识别和打断删除。基于该方法,利用ArcGIS+Python脚本开发了DEM到等高线自动转换工具,在数字广西地理空间框架建设1：1万DLG项目的等高线采集工作中得到了初步应用,取得了良好的效果。  相似文献   

Reconstruction of the western Pacific warm pool SST since 1644 AD and its relation to precipitation over East China     

ZiYin Zhang  DaoYi Gong  XueZhao He  Dong Guo  ShengHui Feng 《中国科学D辑(英文版)》2009,52(9):1436-1446

Based on coral proxies we reconstructed the western Pacific warm pool sea surface temperature (SST) since 1644 AD. High-frequency reconstructions are based on eight high-pass filtered coral series and raw reconstructions are derived from eight unfiltered coral series, respectively. Validation and comparison with other SST/temperature series show that the reconstructed warm pool SST is highly reliable. The leading periods of warm pool SST are ~2.1, ~2.3, ~2.9, ~3.6, ~3.8, and 80.7-year during the last ~360 y...  相似文献   

Regional subsidence of Mexico City and its effects on seismic response     

Javier Avilés  Luis Eduardo Pérez-Rocha 《Soil Dynamics and Earthquake Engineering》2010

Changes expected in Mexico City's seismic response due to land subsidence caused by groundwater extraction are examined. Settlements of the land surface observed in the recent past are compiled and processed to predict regional subsidence in the near future. This information is used in combination with the iso-depth and iso-period maps stipulated by the building code to estimate the compaction of surface sediments and the shortening of soil periods. The time-progressive evolution of the official seismic zoning maps and the associated site-specific response spectra is predicted. The same is done with spectral response contours expressed in terms of the site and structure periods. The subsidence effects are considered through an impact factor, which represents the increase or decrease in the spectral ordinates with respect to the current values specified for design purposes. The detrimental or beneficial effects depend on the relative values of the structure and site periods.  相似文献   

基于Beta样条曲线的等高线绘制研究     

盛庆红 《测绘工程》2010,19(6):24-27

等高线须以相似的光滑曲线逼近实际地貌形态,并综合地形在一定限度内的地势起伏,其智能化控制对地貌表达具有重要的实用价值。绘图员绘制曲线时能凭经验捕捉到数据点所包含的几何形状信息,而张力样条函数和三次B样条曲线在节点插值时,严格要求二阶参数连续,不符合人的经验直觉,是节点对参数曲线连接光滑度的过分限制。根据人工绘制等高线的规则,提出将三次Beta样条曲线作为基于人工绘制约束的等高线插值的数学模型,通过引入形状控制参数放松对曲线的光滑性的要求,增加了控制等高线形状的自由度,把C2连续的三次B样条松弛成为G2连续的Beta样条,实验结果表明插值的等高线符合地形综合度要求。  相似文献   

Preliminary numerical simulation of potential earthquake-induced tsunami in East China Sea   总被引：1，自引：0，他引：1  

温燕林  朱元清  宋治平  薛艳  刘双庆  董非非 《地震学报(英文版)》2008,21(5):456-463

In this paper,we present a numerical simulation of the propagation of a tsunami in the East China Sea,which might be induced by a hypothetical M8.5 earthquake in Okinawa Trough. Our results show that the initial maxi-mum wave height of tsunami could reach as high as 4.3 m for the hypothetical earthquake. It would take 3.5～4 hours for the tsunami to propagate to the coast of Zhejiang Province,and 7～8 hours to the near-shore of Shanghai. The peak tsunami height could be up to about 2 m in the coast of Zhejiang Province. Based on the numerical ex-periments,we plot the arrival time contours of tsunami in East China Sea and time history curves on the three ob-servational stations,and discussed the significance of the pre-analysis.  相似文献   

基于环境包络线法的深水浮式平台极值响应长期预报     

宫浩男  谢波涛  王俊荣  宋佳奇  刘浩 《海洋工程》2021,39(5):28-38

海上结构设计包括对荷载和响应的可靠性评估。对结构进行全面长期响应分析繁琐且费时,故将基于逆一阶可靠性方法的环境包络线进行海上结构概率可靠性分析,对结构的长期响应进行近似估计。在二维标准正态空间中画出与重现期相对应的圆,将圆离散为点后通过Rosenblatt变换转化为环境参数空间中的点来形成闭合的环境包络线。描述海洋环境条件的模型对绘制环境包络线极为重要,基于我国南海荔湾海域40年波浪模拟数据,建立了描述南海波浪的Weibull-Gev条件分布模型,进而绘制南海有效波高—谱峰周期包络线,并与张力腿平台(TLP)系泊张力的长期响应预报结果对比,给出南海海域在波浪作用下应用环境包络线法预报TLP系泊张力的分位数,为未来南海TLP设计中系泊张力预报提供快速估算方法。  相似文献