天线相位中心偏差变化及改正模型对精密单点定位精度的影响   总被引：1，自引：0，他引：1  

涂锐  黄观文  邹顺 《大地测量与地球动力学》2010,30(3)

利用精密单点定位程序对IGS站的实测数据进行计算,结果表明:平面方向,天线相位中心偏差和变化对精密单点定位精度影响较小;高程方向,天线相位中心偏差可造成厘米级的影响,天线相位中心变化的影响约5 mm;相比相对天线相位中心改正模型,使用绝对相位改正模型具有更多优点,尤其用于高精度GPS授时其精度明显提高.  相似文献   

Research and Practice on the Crustal Deformation Mobile Monitoring Network Layout in the Hydropower Station Reservoir Area     

Shang Hong  Liu Tianhai  Zhang Jincheng  Zhang Chengqiang  Yu Haisheng  Sun Baicheng  Yang Huaining  Du Xiaoxia 《中国地震研究》2010,24(3):320-334

According to the construction project of the crustal deformation mobile monitoring network in the cascade hydropower stations built in the lower reaches of Jinsha River,this paper analyzes the design ideas and layout principles of crustal deformation mobile monitoring used in the monitoring of reservoir induced earthquakes. This paper introduces three types of monitoring networks used in the Xiluodu reservoir and Xiangjiaba reservoir, as well as the work already undertaken,in order to provide a kind of reference for the related engineering construction and comprehensive monitoring of reservoir induced earthquakes.  相似文献   

Quantitative Assessment of Impacts of Regional Climate and Human Activities on Saline-alkali Land Changes： A Case Study of Qian＇an County, Jilin Province     

LIAN Yi  WANG Jie  TU Gang  REN Hongling  SHEN Baizhu  ZHI Keguang  LI Shangfeng  GAO Zongting 《中国地理科学(英文版)》2010,20(1):91-97

Interdecadal and interannual variations of saline-alkali land area in Qian’an County, Jilin Province, China were comprehensively analyzed in this paper by means of satellite remote sensing interpretation, field flux observations and regional climate diagnosis. The results show that on the interannual scale, the impact of climate factors accounts for 71.6% of the total variation of the saline-alkali land area, and that of human activities accounts for 28.4%. Therefore the impact of climate factors is obviously greater than that of human activities. On the interdecadal scale, the impact of climate factors on the increase of the saline-alkali land area accounts for 43.2%, and that of human activities accounts for 56.8%. The impact of human activities on the variation of saline-alkali land area is very clear on the interdecadal scale, and the negative impact of human activities on the environment should not be negligible. Besides, changes in the area of heavy saline-alkali land have some indication for development of saline-alkali land in Qian’an County.  相似文献   

国内外流感监测系统的地理流行病学比较研究     

闫磊  任玉环  黄晓霞  张彦平  刘亚岚  王世文 《地球信息科学学报》2010,12(3):410-418

流感监测系统的建立是应对流感大流行的一种极为有效的举措。为此,美国、加拿大、墨西哥、巴西、英国、欧盟、俄罗斯、澳大利亚、新西兰、中国等国家,先后都建立了自己的流感监测系统。为了提高我国流感监测系统的水平,作者选出代表性强、特色显著的美国、欧洲和我国的流感监测系统作为典型,从地理流行病学的角度,着重对流感监测及其数据分析的地理分区、流感疫情动态变化的评价标准等方面进行了比较研究。通过总结先进国家的成熟经验,结合我国的实际情况和需求,作者对我国的流感监测系统提出了改进意见。在综合考虑我国地貌特点、气候分区和管理需要的基础上,建议将现有以秦岭淮河为界划分的南、北两个地理分区,细化为黑吉辽区、京津冀鲁豫区、长江中下游区、闽粤桂琼台区、蒙甘新区、晋陕宁区、渝黔川滇区和青藏区等8个流感监测地理分区;建议将现有流感监测系统引入基于流感样病例占门诊病例百分数的基线,利用归因肺炎及流感的死亡率,计算流感季节基线和流行阈值,以客观地衡量和评价流感流行水平及其严重程度。这些研究成果,不仅对地理流行病学的发展有理论意义,而且也对流感及其他传染病的监测有实用价值。  相似文献   

Focusing phenomenon and near-trapped modes of SH waves     

Jeng-Tzong Chen  Jia-Wei Lee  Ya-Ching Tu 《地震工程与工程振动(英文版)》2016,15(3):477-486

In this study, the null-field boundary integral equation method (BIEM) and the image method are used to solve the SH wave scattering problem containing semi-circular canyons and circular tunnels. To fully utilize the analytical property of circular geometry, the polar coordinates are used to expand the closed-form fundamental solution to the degenerate kernel, and the Fourier series is also introduced to represent the boundary density. By collocating boundary points to match boundary condition on the boundary, a linear algebraic system is constructed. The unknown coefficients in the algebraic system can be easily determined. In this way, a semi-analytical approach is developed. Following the experience of near-trapped modes in water wave problems of the full plane, the focusing phenomenon and near-trapped modes for the SH wave problem of the half-plane are solved, since the two problems obey the same mathematical model. In this study, it is found that the SH wave problem containing two semi-circular canyons and a circular tunnel has the near-trapped mode and the focusing phenomenon for a special incident angle and wavenumber. In this situation, the amplification factor for the amplitude of displacement is over 300.  相似文献   

基于高斯曲线拟合-FFT方法的南海风场反演     

田斯妤  黄晓霞  李红旮  汪昊  李霞  程鹏 《地球信息科学学报》2016,18(11):1544-1550

海面风场是海洋学的基本参量,获取海面风场对了解海洋的物理过程以及海洋与大气之间的相互作用至关重要。宽阔的海域面积及复杂的海面状况通常使南海海面上的风场信息很难被及时获取。ENVISAT ASAR是一种全天候全天时监测海面的微波雷达传感器,可实时获取海面风场数据。本文基于已有ASAR数据对南海海面风场进行反演实验,首先将结合高斯曲线拟合的FFT风向反演方法应用于南海风向反演,并参考Cross-Calibrated Multi-Platform （CCMP）风场数据去除180o方向模糊获得海面风向。然后,将高斯曲线拟合-FFT风向与传统的峰值-FFT风向进行对比,最后将准确率较高的高斯曲线拟合-FFT风向分别输入CMOD4模型和CMOD5模型获得海面风速大小。实验结果与CCMP参考数据的比较结果表明,在风条纹不明显的情况下,利用结合高斯曲线的FFT风向反演方法和CMOD4模型风速反演方法可有效地进行南海海面风场反演。该成果对利用SAR数据实时获取南海大面积海面风场信息,尤其是观测点缺乏海域的风场信息,具有重要的指导意义。  相似文献   

基于网络团购的虚拟旅游流空间差异及动力机制研究   总被引：1，自引：0，他引：1  

涂玮  黄震方  方叶林 《地域研究与开发》2013,32(4)

以旅游产品网络团购为研究视角,以中国26个旅游地旅游产品网络团购虚拟旅游流为研究数据,通过空间分析方法,研究虚拟旅游流的空间分布差异及形成动力机制.网络团购虚拟旅游流整体上表现出微弱离散分布特征,局部表现出一定的聚集性,总的来说虚拟客流集中于南方沿海与中部旅游资源丰富省域,中偏西部、华北及东北地区团购虚拟旅游流量较小;团购虚拟旅游流的空间分布是内外部驱动力及环境驱动力共同作用的结果,其中外部驱动力包括产品团购价格、产品类型、网络营销空间结构3个主要动力因素,相关分析表明团购价格是最主要的外部驱动因素,其次为产品类型,最后为网络营销空间结构;以团购虚拟旅游流为研究视角具有一定的新颖性,弥补了旅游流在虚拟空间研究薄弱的缺陷.虚拟旅游流流向能够在一定程度上反映现实旅游流,甚至导引现实旅游流,虚拟旅游流的研究为景区人流管理、景区容量管理提供预知警告.  相似文献   

Seismic Sequence Characteristics and Precursory Anomalies of the Ms6.3 and Ms6.4 Da Qaidam Earthquakes in 2008 ～ 2009     

Ma Yuhu  Liu Wenbang  Wang Peiling  Yang Xiaoxia  Chen Yuhua 《中国地震研究》2013,27(2)

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Middle Devonian-Tournaisian rocks and biota on Hainan Island, South China     

ZHANG RenJie  YAO HuaZhou  WANG JianXiong  TU Bing 《中国科学:地球科学(英文版)》2013,56(11):1934-1941

On the basis of new paleontological data,the sequence and distributions of the Middle Devonian-Tournaisian rocks on Hainan Island have been sorted out for the first time.The Devonian rocks include the Middle Devonian Jinbo Formation and the Upper Devonian Changjiang Formation,which are distributed in northwestern Hainan Island.The Jinbo Formation is represented by631 m of littoral facies deposits,and was intruded by the Yanshanian granite in the base.The presence of chitinozoans Eisenackitina caster,Funsochitina pilosa,and Lagenochitina amottensis indicates the Givetian in age.The Changjiang Formation is made up of 140 m of neritic facies rocks,and contains the Famennian conodonts Palmatolepis gracilis sigmoidalis,Polygnathus germanus,and corals Cystophrentis kalaohoensis.The Devonian-Tournaisian transition beds,the lower part of the Jishi Formation,are composed of 61–129 m sandstone and siltstone,with gastropods Euomphalus spp.and brachiopods,and marked by conglomerate with the underlying Devonian rocks.The middle-upper part of the Tournaisian Jishi Formation consists of 100–251 m clastic and carbonate rocks,containing abundant corals Pseudoularinia irregularis,conodonts Siphonodella isosticha,trilobites Weberiphillipsia linguiformis,and brachiopods.On the basis of the occurrence of Xinanosprifer flabellum and Homotoma sp.,the Nanhao Formation in southern Hainan Island is now regarded as the Lower Silurian,instead of the previously designated Lower Carboniferous.It is confirmed that no Carboniferous rocks occurred in the area south to the Gancheng-Wanning Fault.  相似文献   

The hypermedia data model based on the infinity image     

Wan Xiaoxia 《地球空间信息科学学报》2013,16(4):48-53

This paper presents the hypermedia data model based on the infinity RS image information system we have developed. The hypermedia data model consists of different semantic units called nodes, and the associations between nodes are called links. This paper proposes three kinds of nodes (interior node, physical node and complex node) and two kinds of links (plane network structure link, hyper-cube network structure links). The hypermedia information system, based on the model and the basic data layer (the infiniy RS image), represents a digital globe. An approach to the “Getting Lost in the Hyper-space” problem is presented. The approach using the hypermedia data model is an efficient way of handling a large number of RS images in various geographical information systems.  相似文献