Deploying a Locata network to enable precise positioning in urban canyons   总被引：1，自引：0，他引：1  

J. -P. Montillet  G. W. Roberts  C. Hancock  X. Meng  O. Ogundipe  J. Barnes 《Journal of Geodesy》2009,83(2):91-103

Locata is a new positioning technology developed by the Locata Corporation. At the beginning of 2007, the Institute of Engineering Surveying and Space Geodesy (IESSG) bought and received a network of Locata transceivers with two rovers. The purpose is to solve the challenges identified when surveying in dense multipath areas (i.e. urban canyons). In this paper, the technology is tested in an urban canyon scenario on the University park at the University of Nottingham. By comparing Locata position solutions with the true positions calculated with a total station and a carrier-phase GPS, the results show that centimetre-level accuracy is achievable in difficult environments in the presence of Wi-Fi signals. The rover’s estimated coordinates may diverge in some cases. Finally, a comparison study shows that Real Time Kinematic GPS and Locata technologies have similar accuracy when both are available.  相似文献   

小钦岛土壤理化性质及其影响因子          下载免费PDF全文

韩春梅  衣华鹏  位彬  高猛  兰思群  刘宗元 《应用海洋学学报》2019,38(1):62-67

利用样带与样方结合法进行野外调查,测定土壤主要理化指标,基于SPSS 24. 0进行皮尔逊(Pearson)相关性分析、单因素方差(One-way ANOVA)分析和最小显著差数法(LSD)多重比较,对小钦岛土壤理化性质的统计学特征及其影响因子进行研究.小钦岛土壤砾石比和含水量平均值分别为20. 04%、7. 35%;铵态氮、速效钾、速效磷、有机质含量平均值分别为23. 67、212. 77、16. 15mg/kg、28. 34 g/kg,分别属于五级、一级、三级和三级水平,大部分属于三级土壤;有机质与含水量、铵态氮、速效磷均呈显著正相关.土壤理化性质主要受植被和坡向影响.通过丰富、加深对庙岛群岛的研究,旨在为海岛的生态保护及开发提供参考.  相似文献   

Distribution characteristics of pelagic Amphipoda in the Changjiang Estuary and adjacent waters          下载免费PDF全文

CAI Meng  XU Zhao-li  ZHU De-di 《海洋学报》2008,30(5)

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Scenarios of land cover in China   总被引：3，自引：0，他引：3  

Tian Xiang Yue  Ze Meng Fan  Ji Yuan Liu 《Global and Planetary Change》2007,55(4):317-342

A method for surface modeling of land cover change (SMLC) is developed on the basis of establishing transition probability matrixes between land cover types and HLZ types. SMLC is used to simulate land cover scenarios of China for the years 2039, 2069 and 2099, for which HLZ scenarios are first simulated in terms of HadCM3 climatic scenarios that are downscaled in zonal model of spatial climate change in China. This paper also analyzes spatial distribution of land cover types, area change and mean center shift of each land cover type, ecotope diversity, and patch connectivity under the land cover scenarios. The results show that cultivated land would decrease and woodland would expand greatly with climatic change, which coincides with consequences expected by implementation of Grain-for-Green policy. Nival area would shrink, and desertification area would expand at a comparatively slow rate in future 100 years. Climate change would generally cause less ecotope diversity and more patch connectivity. Ecosystems in China would have a pattern of beneficial cycle after efficient ecological conservation and restoration. However, if human activities would exceed regulation capacity of ecosystems themselves, the ecosystems in China might deteriorate more seriously.  相似文献   

Hydrogen embrittlement of hot-dip Zn-5%Al coated steel exposed to seawater          下载免费PDF全文

LIU Meng  ZHANG Yu-zhi  ZHANG Da-lei  LI Yan 《海洋科学》2008,32(9)

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广西钦州湾海域游泳动物群落种类组成及多样性研究          下载免费PDF全文

莫珍妮  赖廷和  何斌源  刘昕明  李梦  李英花  宁秋云 《应用海洋学学报》2020,39(2):206-213

根据2015—2016年连续两年对钦州湾进行的拖网调查资料,对钦州湾游泳动物群落的多样性现状进行了初步分析。结果表明,2015、2016年游泳动物调查渔获物种类均为55种;两年共同渔获物优势种(IRI≥200)有5种,分别是钝齿蟳(Charybdis hellerii)、近缘新对虾(Metapenaeus affinis)、周氏新对虾(Metapenaeus joyneri)、亨氏仿对虾(Parapenaeopsis hungerfordi)和口虾蛄(Oratosquilla oratoria),优势种类个体呈现小型化和低龄化趋势,渔获物种类和现存资源较历史数据有衰减的趋势;Shannon-Wiener指数(H′)、丰富度指数(D)和均匀度指数(J′)变化不显著,但站位间差异明显;2016年较2015年调查游泳生物的生物量和资源密度有所回升,但多样性水平均低于北部湾及南海北部大陆架浅海海域的多样性水平。  相似文献   

高平4水平井组双保钻井液技术     

胡祖彪  骆胜伟  孟凡金  陈秉炜  石仲元  金虎 《海洋地质译丛》2009,(1):110-115

高平4井组水平井主要用于开发安塞长10组油藏。针对该井组上部直罗组和富县组易坍塌、下部地层钻速相对较慢、地层易造浆的特点，研究应用了环保型聚硅酸盐-黄胞胶钻井液体系。该体系具有抑制性强、润滑和剪切稀释性好的特点，有利于安全快速钻井，对环境污染极小。通过小型配浆实验确定钻井液施工方案，中测后稀释钻井液，降低钻井液滤失量和密度，加强固相控制，使用保护油层的酸溶性暂堵剂和降滤失剂，可最大限度地保护油层。  相似文献   

Secure Socket Layer协议在电子政务系统安全建设中的应用     

孟昊晨 《国土资源信息化》2009,(5):13-18,28

针对目前日益突出的电子政务安全问题，在Secure Socket Layer协议的基础上，对我国电子政务的安全问题进行探讨，并针对目前政府机构信息化建设中的数据安全传输问题提出几点改进工作方案。  相似文献   

Information Graphics: A comprehensive Illustrated Reference: Robert L. Harris, Oxford University Press, New York & Oxford, 1999, 448 pp. ISBN 0-19-5135326, £32.50     

Xingmin Meng 《Quaternary Science Reviews》2000,19(17-18)

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Evolutionary model of free economic zones     

Meng Guang-wen 《中国地理科学(英文版)》2005,15(2):103-112

Free economic zone (FEZ) has a long history and plays a more and more important role in the world economy. Most studies, however, focused on the theoretical analysis of benefit and cost as well as the economic role of FEZ in the less developed countries and little attention has been paid to the evolution of FEZ. This paper will improve the above-mentioned studies and put forward the structural and spatial evolutionary model of FEZ by analyzing the development of objectives, preferential policy, governance structure, industrial sectors and location of FEZs based on the international economic and political development. FEZs develop towards: 1) more comprehensive and macro objectives, 2) more industry-oriented and multi-preferential policies, 3) more cross-national and combination zones with administrative areas, 4) more technology-intensive and multi-industries, 5) more flexible location and larger spatial dimensions, 6) more rapid evolution and typologies, and 7) more economic integration to the host economy. Biography: MENG Guang-wen (1960–), male, a native of Tianjin of China, Ph.D., specialized in regional planning and policy, environmental planning, tourist planning and management. E-mail: gwmeng98@hotmail.com  相似文献