检索结果-南通市图书馆

Antarctic Traverses from Zhongshan Station to Dome-A and the Result Analysis for the GPS Points along the expedition Route

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2002年第1期5卷 31-36页

作者： WANG Qinghua e dongchen CHeN Chunming School of Geodesy and Geomatics Wuhan University Wuhan China

Some GPS points were set up and occupied and reoccupied along the traverse route from Zhongshan Station to *** result analysis for the GPS data processed by GAMIT/GLOBK package was presented in this *** was indicated that the ice along the traverse route flowed with an 825 m/a velocity to the northwest in the last three years,which was the direction of the edge of the ice *** maximum horizontal flow velocity is about 100 m/***,due to the ice flow,a 0.21 m/a sedimentation rate is ***,a 15 m/a 2 horizontal acceleration is achieved from the GPS data of the three different stages.

关键词： Antarctic inland ice_sheet traverse Dome_A GPS GAMIT/GLOBK ice flow

Sea ice concentration over the Antarctic Ocean from satellite pulse altimetry

在线全文

学校读者我要写书评

暂无评论

Science China earth Sciences 2011年第1期54卷 113-118页

作者： YANG YuanDe e dongchen WANG ,HaiHong CHAO DingBo HWANG CheinWay LI Fei AI SongTao Chinese Antarctic Center of Surveying and Mapping Wuhan University Wuhan 430079 China School of Geodesy and Geomatics Wuhan University Wuhan 430079 China Key Laboratory of Surveying and Mapping Technology on Island and Reef State Bureau of Surveying and Mapping Qingdao 266510 China Department of Civil engineering 'National' Chiao Tung University Hsinchu Taiwan China

Sea ice concentration (SIC) is an important parameter in characterizing sea ice. Limited by the environment and the spatial extent of observation, it is difficult for field work to meet the needs of a large-scale SIC study. However, with its many advantages, such as the ability to make large-scale, high-resolution and long-duration observations, the altimeter can be used to determine SIC on a large scale. Using the correspondence between the satellite pulse altimeter waveform and reflector property, waveform classification is employed. Moreover, this paper develops an algorithm to obtain the SIC from altimeter waveforms. In an actual computation, Pyrz Bay in the Antarctic is taken as an experimental region, and one-year and seasonal SICs are derived from eRS-1/GM waveforms over this study area. Furthermore, altimetric SICs are compared with those of SSMR SSM/I. The results show that the spatial distribution and the regions of maximum SIC determined employing these two methods are consistent. This demonstrates that altimeter data can be used to monitor sea ice.

关键词： sea ice concentration Antarctic altimeter waveform SSMR SSM/I eRS-1/GM

非对称液压缸位移伺服系统的复合控制策略与试验研究

在线全文

学校读者我要写书评

暂无评论

机床与液压 2024年第3期52卷 131-135页

作者：鄂东辰董兴华蔡玉强王志军路时雨张立杰华北理工大学机械工程学院河北唐山063210 唐山工业职业技术学院河北唐山063210 燕山大学河北省重型机械流体动力传输与控制重点实验室河北秦皇岛066000

非对称液压缸的位移伺服系统存在两腔作用面积不等、系统模型不确定等特点,给液压缸高精度位移跟踪控制造成了巨大的困难。对此,提出以速度前馈为主与位移反馈为辅的复合控制策略。设计一种新的以控制电流和阀口压差为自变量的伺服阀流... 详细信息

非对称液压缸的位移伺服系统存在两腔作用面积不等、系统模型不确定等特点,给液压缸高精度位移跟踪控制造成了巨大的困难。对此,提出以速度前馈为主与位移反馈为辅的复合控制策略。设计一种新的以控制电流和阀口压差为自变量的伺服阀流量计算模型,并根据该模型设计液压测试回路,通过测试结果辨识模型中的参数。根据伺服阀流量模型与目标位移轨迹计算速度前馈控制量。基于PI控制求出位移误差反馈控制量。最后,将速度前馈和位移反馈控制量相叠加作为伺服阀的驱动电压。通过试验得出在复合控制策略下液压缸位移跟踪的最大误差与目标位移幅值之比为2.1%,相对PID控制跟踪误差明显减小。提出的控制策略为生产实际中非对称液压缸的位移跟踪控制提供了一种简单、有效的方法。

关键词：复合控制非对称液压缸流量模型位移伺服系统

Support Vector Machines for Cloud Detection over Ice-Snow Areas

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2007年第2期10卷 117-120页

作者： CHeN Gang e dongchen Department of Geography University of Calgary Calgary T2N 1N4 Canada Chinese Antarctic Center of Surveying and Mapping Wuhan University 129 Luoyu Road Wuhan 430079 China

In polar regions, cloud and underlying ice-snow areas are difficult to distinguish in satellite images because of their high albedo in the visible band and low surface temperature of ice-snow areas in the infrared band. A cloud detection method over ice-snow covered areas in Antarctica is presented. On account of different texture features of cloud and ice-snow areas, five texture features are extracted based on GLCM. Nonlinear SVM is then used to obtain the optimal classification hyperplane from training data. The experiment results indicate that this algorithm performs well in cloud detection in Antarctica, especially for thin cirrus detection. Furthermore, when images are resampled to a quarter or 1/16 of the full size, cloud percentages are still at the same level, while the processing time decreases exponentially.

关键词： cloud detection SVM texture analysis ice-snow covered area polar region

Development of the geodetic coordinate system in Antarctica

在线全文

学校读者我要写书评

暂无评论

Advances in Polar Science 2012年第3期23卷 181-186页

作者： ZHANG Shengkai e dongchen Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430079China Key Laboratory of Polar Surveying and Mapping SBSMWuhan 430079China

Defining a universal geodetic coordinate system is one of the fundamental challenges of geodesy. We present a review of the basic general coordinate systems -- the space rectangular coordinate system, the geodetic coordinate system, the topocentric coordinate system, and the plane coordinate system. We then look ： t the World Geodetic System WGS72 and WGS84 and the In- ternational Terrestrial Reference Frames ITRF2000 and 1TRF2005, which were introduced when space technology became avail- able. The history of international geodetic coordinate systems in the Antarctic region is briefly reviewed and the development of the geodetic coordinate systems in the Chinese Great Wall Station and Zhongshan Station in Antarctica is outlined. Finally, the issue of coordinate system transformation is discussed.

关键词： Antarctic coordinate system ITRF GPS

Progress and prospects in Chinese Antarctic surveying, mapping and remote sensing studies

在线全文

学校读者我要写书评

暂无评论

Advances in Polar Science 2012年第1期23卷 1-8页

作者： e dongchen ZHANG Shengkai Chinese Antarctic Center of Surveying and Mapping Wuhan University Wuhan 430079 China Key Laboratory of Polar Surveying and Mapping SBSM Wuhan 430079 China

Antarctic surveying, mapping and remote sensing is one of the important aspects of the Chinese Antarctic geoscience research program that stretch back over 25 years, since the first Chinese National Antarctic Research expedition （CHINARe） in 1984. During the 1980＇s, the geodetic datum, height system and absolute gravity datum were established at the Great Wall and Zhongshan Stations. Significant contributions have been made by the construction of the Chinese Great Wall, Zhongshan and Kunlun Stations in Antarctica. Geodetic control and gravity networks were established in the King George Islands, Grove Moun- tains and Dome Argus. An area of more than 200 000 km2 has been mapped using satellite image data, aerial photogrammetry and in situ data. Permanent GPS stations and tide gauges have been established at both the Great Wall and Zhongshan Stations. Studies involving plate motion, precise satellite orbit determination, the gravity field, sea level change, and various GPS applications for atmospheric studies have been carried out. Based on remote sensing techniques, studies have been undertaken on ice sheet and glacier movements, the distributions of blue ice and ice crevasses, and ice mass balance. Polar digital and visual mapping tech- niques have been introduced, and a polar survey space database has been built. The Chinese polar scientific expedition manage- ment information system and Chinese PANDA plan display platform were developed, which provides technical support for Chi- nese polar management. Finally, this paper examines prospects for future Chinese Antarctic surveying, mapping and remote sens- ing.

关键词： Antarctic geodesy remote sensing geographic information system digital mapping

Tidal characteristics near the Chinese Zhongshan Station in Prydz Bay, east Antarctica

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2013年第1期4卷 7-15页

作者： Huang Jifeng e dongchen Zhang Shengkai Chinese Antarctic Center of Surveying and Mapping Wuhan University Wuhan University's Key Antarctic Science Laboratory of SBSM

A permanent tidal station was installed at the Chinese Zhongshan Station in Feb. 2010. Harmonic constants of 170 tidal constituents were obtained from harmonic analysis of the first year＇ s data. The results of the eight main constituents showed good agreement with those of two tidal models. Tidal characteristics, such as tide type, diurnal inequality, tidal range, and water levels were also analyzed.

关键词： tidal characteristics harmonic constants tidal models sea level Antarctica

Progress in Chinese Antarctic geodetic remote sensing

在线全文

学校读者我要写书评

暂无评论

Advances in Polar Science 2018年第2期29卷 78-86页

作者： e dongchen WANG Zemin ZHANG Shengkai Chinese Antarctic Center of Surveying and Mapping Wuhan University

This paper summarizes the progress of the Chinese Antarctic expedition in geodetic remote sensing. It describes the systems for continuous satellite navigation and positioning, and the tide gauges that have been established at the Zhongshan and Great Wall stations in Antarctica. Advances in the investigation of plate motion, the gravity field, and sea level change as well as the application of GPS in atmospheric studies are reported. Details of the movements of ice sheets and glaciers, distributions of blue ice and ice crevasses, and mass balance studies based on remote sensing techniques are presented. The use of field, satellite, and photogrammetric data to produce topographic maps is described. Finally, the prospects for further Antarctic surveying and mapping are discussed. In the near future, we will establish a high-precision geodetic datum in the Chinese Antarctic expedition areas, monitor changes of Antarctic snow and ice, and develop a platform for sharing Antarctic resource and environment information.

关键词： Antarctica geodesy remote sensing GIS

基于纹理分析和支持向量机的极地冰雪覆盖区的云层检测

在线全文

学校读者我要写书评

暂无评论

武汉大学学报（信息科学版） 2006年第5期31卷 403-406页

作者：陈刚鄂栋臣武汉大学中国南极测绘研究中心武汉市珞喻路129号430079

使用ASTeR卫星影像,综合运用纹理分析和支持向量机的方法来检测云层,特别是对薄卷云的检测。试验表明了本文方法的有效性。

关键词：云层检测纹理分析支持向量机冰雪覆盖区极地地区