全球定位系统的新进展(讲座五)——信号时延差对电离层延迟的影响     

李征航  龚晓颖 《测绘信息与工程》2012,37(5):61-63,84

介绍电离层延迟改正时需要顾及信号时延差影响的原因,同时讨论并推导了采用各种双频信号进行测距时的电离层延迟模型。  相似文献   

单频RTK动态解算的卡尔曼滤波算法研究     

徐彦田  程鹏飞  蔡艳辉  徐宗秋 《测绘科学》2012,(4):43-44

本文针对单频RTK提出了一种快速动态定位卡尔曼滤波算法,该方法使用C码和L1观测值,用模型改正对流层干延迟,双差大气延迟分解为测站大气天顶延迟和投影函数,与流动站位置以及站间单差模糊度组成观测方程进行卡尔曼滤波,得到单差模糊度浮点解及方差阵,通过星间求差得到双差模糊度浮点解及方差阵,结合MLAMBDA方法实时动态确定模糊度。经实测数据和IGS站数据验证该算法具有较好定位结果。  相似文献   

网络RTK对流层拟合模型分析     

琚兴华 《测绘科学》2012,(1):182-184

为了拟合网络RTK中用户端双差对流层延迟,本文分析了基于距离的线性内插模型(DIM)、线性内插模型(LIM)原理,提出了指数拟合模型:以主参考站为原点,系数项与用户端和辅参考站间夹角成反比,指数底数值为0.35,用户端到主参考站与辅参考站到主参考站间距离比值被1减为指数。通过分析上述模型的误差系数给出了模型优缺点,试验验证了指数模型的有效性和稳定性:卫星拟合精度一般优于2cm,实现了单历元平面定位精度优于2cm,高程精度优于3cm。  相似文献   

云南滇池流域强烈灌溉条件下西芹大棚土壤水分动态特征     

郭华明  李广贺  阎非  张大奕  张旭  卢昌艾 《地质科技情报》2004,23(3):78-82

利用TRIME-T3型TDR仪土壤含水量测量系统和WM-1型负压计系统现场监测了强烈灌溉条件下整个作物生长期西芹大棚土壤水分、土壤负压(基质势)的动态变化;研究表明,不同深度土壤含水量受强烈灌溉的影响程度不同,0.3 m深度处受影响最大,1.0,2.0 m深度处受影响最小;受灌溉的影响,0.3,0.6,1.0 m深度处负压有所波动,其中0.3 m深度处负压的波动幅度最大;2.0 m深度处的土壤一直处于"饱和-非饱和"两种状态的转换之中;在地下水埋深为2.0 m左右,且上部土层的渗透性较差(饱和渗透系数仅为0.04 m/d)的情况下,地下水水位受灌溉的影响极小.  相似文献   

Analysis of systematic error influences on accuracy of airborne laser scanning altimetry     

ZHANGXiaohong LIUJingnan 《地球空间信息科学学报》2004,7(3):218-224

The error sources related to the laser rangefinder, GPS and INS are analyzed in details. Several coordinates systems used in airborne laser scanning are set up, and then the basic formula of system is given.This paper emphasizes on discussing the kinematic offset correction between GPS antenna phase center and laser fired point. And kinematic time delay influence on laser footprint position, the ranging errors, positioning errors, attitude errors and integration errors of the system are also explored. Finally, the result shows that thekinematic time delay can be neglected as compared with other error sources. The accuracy of the coordinates is not only influenced by the amplitude of the error, but also controlled by the operation parameters such as flight height, scanning angle amplitude and attitude magnitude of the platform.  相似文献   

一种求解地球物理参数各向异性的新方法一单位步长变异增量法   总被引：1，自引：0，他引：1  

曹云梦  李志伟  韦建超  占文俊  朱建军  汪长城 《应用地球物理》2014,11(3):340-349

目前在研究地球物理参数的空间变异特性时常常是基于几何各向异性假设,然而实际中几何各向异性假设常常不成立。本文提出了一种求解地球物理参数各向异性的新方法,首先对各方向上的变异值作归一化处理,然后用拟合的方法得到各方向单位步长上的变异性强度,进而实现对全局各向异性的求解。以上海地区合成孔径雷达干涉测量（InSAR）中差分大气延迟样本数据为例,验证了新方法求解各向异性的优越性：新方法的偏差只有6.4%,而基于几何各向异性假设方法的偏差达到了21.2%,而且新方法的运算效率有非常显著的提高。进一步,通过克里金插值交叉验证实验,证明了基于新算法得到的结构函数的插值效果最好,从而从另外一个角度验证了新算法求解的各向异性更准确,更好地表征了区域化变量的空间结构特征。因此,与几何各向异性假设的方法相比,新方法不仅能更准确的描述地球物理参数的各向异性,而且有更高的运算效率,为更准确地估计出所需的地球物理参数奠定了基础。  相似文献   

中国海洋生态文明进程的综合评价与测度          下载免费PDF全文

苗欣茹  王少鹏  席增雷 《海洋开发与管理》2020,37(1):83-91

沿海各省、市、自治区在区位、资源禀赋、经济发展方式及科技发展水平等方面存在差异,致使海洋生态文明呈现不同的发展态势。因此,全面评价海洋生态文明建设进程,对促进沿海各省、市、自治区海洋生态文明优化发展具有重要的现实意义。文章通过构建海洋生态文明进程评价指标体系,运用时序动态综合评价方法和熵值法,测算了2006-2015年中国沿海11个省、市、自治区海洋生态文明建设状况。结果表明:从分指标来看,海洋资源有序开发成果显著,促进了海洋生态文明建设进程,但科研成果转化效率低,海洋产业开发多为中低水平,生态环境改善存在下行压力。从整体来看,沿海11个省、市、自治区海洋生态文明建设存在空间差异。基于以上结论,应从增加海洋产业科技研发投入、合理开发海洋资源、提高海洋生态环境保护意识、加快海洋科技创新等方面着手,以促进海洋生态文明建设的全面、协调和可持续发展。  相似文献   

长距离网络RTK区域电离层延迟实时改正   总被引：1，自引：1，他引：0  

王建敏  吕楠  李亚博 《测绘通报》2019,(5):106-108

针对网络RTK基线过长时电离层延迟的相关性就会减弱的问题，本文提出了一种长距离网络RTK区域电离延迟改正模型。首先利用已知载波值和确定的非差参考模糊度计算基准站的电离层延迟，进而传播至流动站，最后内插计算流动站电离层延迟，得到电离层延迟改正。通过实测CORS数据进行验证，结果表明，该算法可使长距离网络RTK达到厘米级精度的定位结果。  相似文献   

A lattice Boltzmann-finite element model for two-dimensional fluid–structure interaction problems involving shallow waters     

《Advances in water resources》2014

In this paper, a numerical method for the modeling of shallow waters interacting with slender elastic structures is presented. The fluid domain is modeled through the lattice Boltzmann method, while the solid domain is idealized by corotational beam finite elements undergoing large displacements. Structure dynamics is predicted by using the time discontinuous Galerkin method and the fluid–structure interface conditions are handled by the Immersed Boundary method. An explicit coupling strategy to combine the adopted numerical methods is proposed and its effectiveness is tested by computing the error in terms of the energy that is artificially introduced at the fluid–solid interface.  相似文献   

Migrant times beyond the life course: The temporalities of foreign English teachers in South Korea     

《Geoforum》2015

The study of life course has become a central feature of geographical and other social science approaches to youth and migration. It has offered scholars possibilities to explore the timing of events, experiences of time and in the context of migration, the opportunity to analyse mobility patterns in relation to life stages and transitions. Yet, despite this emphasis, much life-course research rests on a limited understanding of time characterised as a linear or even static entity that regulates life in a way that occludes the complex directionality and rhythms of time. In this paper we seek to push beyond these limitations of life course research by developing broader theoretical understandings of time in migration. In particular, we develop a Heideggerian analysis of the migration stories of western English teachers in South Korea, an example of migration as part of a youth–adult transition. Our analysis reveals that the mobilities of English teachers need to be understood in much more complex and relational ways and we draw attention to their more-than-subjective temporalities, questions of attunement to being (affect) and temporal openness in migration. Through this discussion the paper highlights three key areas for further development of scholarly understandings of time in migration: the situatedness of migrants, the holistic character of migration as a happening in the world, and the eventfulness of migration, always characterised by an openness of possibility for emergent spatio-temporal differentiation.  相似文献