Assessment of code bias variations of BDS triple-frequency signals and their impacts on ambiguity resolution for long baselines     

Lou  Yidong  Gong  Xiaopeng  Gu  Shengfeng  Zheng  Fu  Feng  Yanming 《GPS Solutions》2017,21(1):177-186

GPS Solutions - Carrier phase ambiguity resolution over long baselines is challenging in BDS data processing. This is partially due to the variations of the hardware biases in BDS code signals and...  相似文献   

Till‐forming processes beneath parts of the Cordilleran Ice Sheet,British Columbia,Canada: macroscale and microscale evidence and a new statistical technique for analysing microstructure data     

Christina M. Neudorf  Tracy A. Brennand  Olav B. Lian 《Boreas: An International Journal of Quaternary Research》2013,42(4):848-875

This paper presents the first integrated macroscale and microscale examination of subglacial till associated with the last‐glacial (Fraser Glaciation) Cordilleran Ice Sheet (CIS). A new statistical approach to quantifying till micromorphology (multivariate hierarchical cluster analysis for compositional data) is also described and implemented. Till macrostructures, macrofabrics and microstructures support previous assertions that primary till in this region formed through a combination of lodgement and deformation processes in a temperate subglacial environment. Macroscale observations suggest that subglacial environments below the CIS were probably influenced by topography, whereby poor drainage of the substrate in topographically constricted areas, or on slopes adverse to the ice‐flow direction at glacial maximum, facilitated ductile deformation of the glacier bed. Microscale observations suggest that subglacial till below the CIS experienced both ductile and brittle deformation, including grain rotation and squeeze flow of sediment between grains under moist conditions, and microshearing, grain stacking and grain fracturing under well‐drained conditions. Macroscale observations suggest that ductile deformation events were probably followed by brittle deformation events as the substrate subsequently drained. The prevalence of ductile‐type microstructures in most till exposures investigated in this study suggests that ductile deformation signatures can be preserved at the microscale after brittle deformation events that result in larger‐scale fractures and shear structures. It is likely that microscale ductile deformation can also occur within distributed shear zones during lodgement processes. Cluster analysis of microstructure data and qualitative observations made from thin sections suggest that the relative frequency of countable microstructures in this till is influenced by topography in relation to ice‐flow direction (bed drainage conditions) as well as by the frequency and distribution of voids in the till matrix and skeletal grain shapes.  相似文献   

水流挟沙力分析与探讨   总被引：4，自引：0，他引：4  

李瑞杰  罗锋  周华民 《海洋湖沼通报》2009,(1)

水流挟沙力是悬沙输运计算中非常重要的问题之一,其计算形式常采用基于重力理论的经验和半经验公式.本文针对目前广泛采用的2种挟沙力关系式,选用4组实验水槽数据和2组天然河道实测资料分别讨论其关联性.结果表明,不论指数m在其取值范围内取何值,2个表达式皆存在一定的函数关联性.且当指数m取1和2/3时,直接表现出很强的线性关联.在挟沙力计算中采用流速的平方关系式,物理意义清晰,形式简单.在实际应用时,适当选取系数,挟沙力采用形式简单的平方关系式是完全可行的.  相似文献   

连续运行参考站系统的建设及其在测量中的应用   总被引：1，自引：1，他引：0  

徐锋  宗强  张沥 《测绘与空间地理信息》2009,32(3):100-102

介绍了苏州市GPS连续运行参考站系统的建设及其在测量中的应用,详述了系统的原理,各组成部分的功能,以及在测量领域中的应用,供各位同行参考.  相似文献   

湖北随州 ML4.7地震序列基础资料分析     

李峰  李垠  薛军蓉  陈俊华 《大地测量与地球动力学》2007,27(Z1):56-61,88

依据随州三里岗ML4.7地震序列的地震监测和宏观调查所获得的基础资料,对此次地震序列的时空强特征及地震成因机理进行了分析。为使地震资料准确可靠,对混淆在序列中的爆破波形与地震波形进行了鉴别和剔除。结合这些基础资料和震源机制解结果。分析认为随州地震序列在成因上与该地区存在的北东和北西向两组断裂构造有关,但主发震构造是北西向断裂。  相似文献   

海滩养护和修复工程的动态平衡滨线设计研究——以浙江省苍南县炎亭湾海滩修复工程设计为例          下载免费PDF全文

曹惠美  蔡锋  苏贤泽  朱君 《应用海洋学学报》2018,37(2):185-193

以浙江省苍南县炎亭湾海滩修复为例,基于"CERC"的沿岸输沙率计算公式,建立了一套依据工程区近滨波浪场分布进行动态平衡滨线设计的方法,包括独立输沙单元海滩和非独立输沙单元海滩2种滨线形态设计方法.研究发现:在海滩养护和修复工程中,依据动态平衡滨线设计方法对滨线走向进行科学论证是十分必要的;独立输沙单元的海滩可以视为沿岸输沙率为零的非独立输沙单元的海滩,前者海滩平衡滨线的布设是后者平衡滨线布设的一种特例;相较于"静态岬湾海滩概念(SBBC)"模型,本研究提出的动态平衡滨线设计方法更具优势,该方法可用于大多数海滩的平面形态设计.  相似文献   

On the Collision Nature of Two Coronal Mass Ejections: A Review   总被引：1，自引：0，他引：1  

Fang Shen  Yuming Wang  Chenglong Shen  Xueshang Feng 《Solar physics》2017,292(8):104

Observational and numerical studies have shown that the kinematic characteristics of two or more coronal mass ejections (CMEs) may change significantly after a CME collision. The collision of CMEs can have a different nature, i.e. inelastic, elastic, and superelastic processes, depending on their initial kinematic characteristics. In this article, we first review the existing definitions of collision types including Newton’s classical definition, the energy definition, Poisson’s definition, and Stronge’s definition, of which the first two were used in the studies of CME–CME collisions. Then, we review the recent research progresses on the nature of CME–CME collisions with the focus on which CME kinematic properties affect the collision nature. It is shown that observational analysis and numerical simulations can both yield an inelastic, perfectly inelastic, merging-like collision, or a high possibility of a superelastic collision. Meanwhile, previous studies based on a 3D collision picture suggested that a low approaching speed of two CMEs is favorable for a superelastic nature. Since CMEs are an expanding magnetized plasma structure, the CME collision process is quite complex, and we discuss this complexity. Moreover, the models used in both observational and numerical studies contain many limitations. All of the previous studies on collisions have not shown the separation of two colliding CMEs after a collision. Therefore the collision between CMEs cannot be considered as an ideal process in the context of a classical Newtonian definition. In addition, many factors are not considered in either observational analysis or numerical studies, e.g. CME-driven shocks and magnetic reconnections. Owing to the complexity of the CME collision process, a more detailed and in-depth observational analysis and simulation work are needed to fully understand the CME collision process.  相似文献   

Southern high latitude climate anomalies associated with the Indian Ocean dipole mode     

刘娜贾贞  陈红霞华锋 《中国海洋湖沼学报》2006,24(2):125-128

1 INTRODUCTION In southern high latitudes, recent observations have shown a standing mode of ACW (Antarctic Circumpolar Wave) with eastward propagation across the Southern Ocean of the Antarctic in co- varying SST (sea surface temperature) and SLP (sea le…  相似文献   

西南极菲尔德斯半岛白垩纪晚期和第三纪早期岩石的古地磁学及其大地构造意义          下载免费PDF全文

刘椿  朱日祥  郑祥身  刘小汉  金增信  冯宇 《极地研究》1991,3(2):136-143

采自菲尔德斯半岛白垩纪晚期和第三纪早期五个岩层单位的12个采点109块定向岩芯标本进行了系统的古地磁学测定,从中得知,55～45Ma时期,该区极位置与澳大利亚的同时期结果不同,它经历了大约20°～30°的南向水平移动与70°～80°的西向旋转,逐渐地构成了今日彼此相对位置的格架。文章绘制出南极洲的视极移曲线。  相似文献   

ON THE BEHAVIORS OF OCEAN BOTTOM EDDY     

吴德星  冯土 《中国海洋湖沼学报》1994,12(4):343-350

On the basis of scaling analysis,this paper presents a frontal geostrophic dynamic system which canbe used to describe the dynamics of an isolated bottom eddy and shows that five possible dynamicsubregimes are included in the system.A particle-in-cell method is used to investigate the behavior of the eddy in the two dynamic subregimes,with 1)nonlinear effect(ε)relevant to the sloping bottom-inducedbeta effect(β_1)and 2)seamount-induced beta effect(β_2)dominant.In the dynamic subregime of β_1～ ε～10~(-2)and β_2=0,the eddy can keep as a whole for a long time and migrates for a long distance.Inthe dynamic subregime where the seamount-induced beta effect (β_2～10~(-1))is dominant,the seamounttraps the water particles,causing the eddy to break up into a discrete set of eddies moving around the seamount.  相似文献