Three-dimensional Reconstruction of the Yaolin Cave     

《制图学和地理信息科学》2013,40(1):31-40

This paper reports on three-dimensional reconstruction of the Yaolin Cave in the Karst Region of Zhejiang, China. An object-oriented method was used to represent two cave classes—the class Boundary and the class Inside. The class Boundary included objects of the cave ceiling and the cave floor which are part of the topographical trend of the cave. This trend was determined by integrating topography with landform using TIN modeling. The inside of the cave with stalagmites, stalactites, dripstone-columns, and other objects was built using surveying data, photographs, and such computer graphics techniques as texture mapping and transparency. A stand-alone, 3-D visualization system—Cave3D—was developed on the Windows 98/NT platform to produce 3-D graphics and implement graphics-based computation, spatial query, and analyses. A virtual Yaolin cave was created using VRML97 and Java and posted on the Web.  相似文献   

基于ACCESS VBA的坐标转换程序设计     

李子轩  宫雨生  殷和健  高松涛  张雪恒 《测绘与空间地理信息》2016,(7)

随着空间定位技术的普及,不同空间直角坐标系间的转换过程中经常遇到问题不易被解决。本文首先介绍了不同空间直角坐标系间转换时广泛使用的布尔沙转换模型并阐述了七参数求解的过程,然后结合ACCESS中的表、窗体和宏,利用VBA实现了基于布尔沙转换模型的七参数计算程序,并结合实例对所编写的程序加以验证,保证其结果的可靠性。  相似文献   

The role of diversification in dynamic small-scale fisheries: Lessons from Baja California Sur,Mexico     

《Global Environmental Change》2015

Globally, small-scale fisheries are critical for livelihoods and food security yet face increasing uncertainty and variability from processes such as overfishing, globalization, and climate change. Enhancing the number of options for human response through increased access to marine resources, diverse livelihood approaches, and generalist fishing strategies may attenuate the negative effects of change and disturbance. My research explores the relative importance of diversification strategies for achieving resilient small-scale fishing communities and cooperatives of Baja California Sur, Mexico. Specifically, interview data and long-term catch and economic data were used to develop an economic metric of resilience, in addition to income diversification indices, for fishing cooperatives. Fishing cooperative characteristics and environmental conditions were then evaluated as possible predictors of cooperatives’ relative ability to diversify. I found that while diversification was important for risk mitigation and stabilizing income, the ability of cooperatives to specialize during favorable conditions may be important for poverty reduction and wealth accumulation. Thus, the flexibility to move across fishing strategies given changing environmental conditions is important for the adaptive capacity of small-scale fishing cooperatives. My findings will contribute to a better understanding of the institutional arrangements that promote a resilient small-scale fishery, and therefore, will be invaluable for practitioners of small-scale fisheries.  相似文献   

珠江口SX97孔7 000 a B.P.的气候环境变化及流域响应     

周厚云  余素华  郭国章 《地理科学》2001,21(4):368-372

综合考虑矿物，元素地球化学和孢粉等多方面的资料，对珠江口北岸SX97孔揭示的7000a B.P.以来的气候环境演化提出了一种5阶段划分方案。这种阶段性在SX97孔的各项指标上均有很好的对应，也与华南地区基于海岸沙丘，海滩岩和海相沉积地层等的早期研究成果能较好地对应。在此基础上，初步探讨了气候环境变化中的流域响应，发现SX97孔揭示出气候环境变化中很有很好的流域响应。如当气候环境偏湿偏热时，流域风化作用更加强烈，有很更多的铁元素流失，同时流域植被更发育，对降水有更好的缓冲作用，导致河口沉积物中含有更的铁元素（包括二价铁和三价铁），更少石英矿物和更多粘土矿物，当气候环境偏干偏凉时则相反。  相似文献   

珠江口SX97孔7000aB.P.以来石英矿物含量反映的气候变化     

周厚云  郭国章  余素华 《热带海洋学报》2001,20(4):1-5

珠江口北岸SX97孔的石英矿物含量变化与该孔孢粉数据及华南沿海其它地质地貌资料所揭示的古气候古环境演化能很好对应。古气候古环境通过控制物源区的植被发育、风化强度和侵蚀能力及河口沉积区的进退，对河口沉积物中石英矿物含量有很好的调控作用。在华南沿海地区，河口沉积物中的石英矿物含量可能是指示气候环境演化的一个方便和实用的指标。  相似文献   

用RAM扩充程序存贮器     

王立红 《中国海洋大学学报(自然科学版)》1995,(Z1)

给出一种用ＲＡＭ扩充程序存贮器的方法，以及具体的硬件线路。这种简便实用的方法可为用户提供一种根据需要自行修改或编写应用程序的环境．  相似文献   

Carbon and nitrogen isotope excursions in mid-Pleistocene sapropels from the Tyrrhenian Basin: Evidence for climate-induced increases in microbial primary production     

Philip A. Meyers  Stefano M. Bernasconi 《Marine Geology》2005,220(1-4):41-58

The modern Mediterranean Sea is oligotrophic, yet its sediment record contains layers of organic-carbon-rich sapropels at 21 ky (precessional) spacing that imply periods of elevated paleoproductivity that approached the high productivities of modern upwelling systems. Resolution to this paradox is provided by lines of evidence suggesting that the mode of primary productivity changed from one dominated by algae to one during times of sapropel deposition in which photosynthetic bacteria were important. We have made a high-resolution comparison of the organic carbon and nitrogen isotopic compositions of three sapropels and their background sediments in a 3-m sequence that corresponds to 1001 to 946 ka. Organic δ¹³C values systematically increase from − 26‰ to − 21‰ and δ¹⁵N values systematically decrease from 4‰ to < 0‰ as organic carbon mass accumulation rates increase in the sapropel layers. The increase in carbon isotope values mirrors the increases in primary productivity and associated organic matter export indicated by the increased mass accumulation rates. The decrease in nitrogen isotope values implies major contributions of nitrogen-fixing cyanobacteria to the total marine productivity. The precessional minima with which sapropels coincide were times of wetter climate that stratified the surface Mediterranean Sea, increased delivery of soil-derived phosphorus, and evidently amplified microbial primary production. Our high-resolution study reveals several relatively rapid excursions into and out of the high-productivity mode that suggest that sapropel deposition was a climate-sensitive surface-driven phenomenon that was not accompanied by basin-wide stagnation.  相似文献   

基于VBA的防震减灾办公自动化系统的设计与实现          下载免费PDF全文

周明辉  赵成文  马忠宏  张波  张东亚  余中元 《地震工程学报》2007,29(2):192-196

VBA是集成在Word中的开发语言,编程结果可直接产生Word文档。本文结合地震系统防震减灾“三大工作体系”建设,分析了国家有关法律法规和中国地震局及甘肃省地震局发布的规范性文件、执法文书、审批报表及宏观异常填报表等的格式要求和特征,进行了系统分析和系统设计,利用Visual BASIC语言嵌入VBA指令开发了防震减灾办公自动化系统。  相似文献   

Access 在农业气象情报服务中的应用     

邓彪 《高原山地气象研究》2002,22(1)

本文结合农业气象情报服务工作实践,阐述了如何利用Access数据库系统和VB6.0实现对农情资料传输、添加和分析系统.  相似文献   

ITRF97参考框架下的中国大陆区域地壳板块运动背景场的建立及应用   总被引：6，自引：0，他引：6  

姚宜斌  刘经南  施闯  陶本藻 《武汉大学学报(信息科学版)》2002,27(4):363-366,376

利用中国地壳运动观测网络工程基准站和基本站的GPS实测结果，构造了一个ITRF参考框架下的、充分反映今板块运动特征的、更为精确的现状中国大陆区域板块运动模型，介绍了这一工作的思路、方法和最终结果，并对速度场结果作了初步的解释。  相似文献