不同天线组合对GPS姿态测量精度的影响分析          下载免费PDF全文

鲁洋为  王振杰  聂志喜  王毅 《海洋测绘》2014,34(6):43-45,48

GPS姿态确定的精度不仅与单历元基线解算精度有关,还受基线长度和天线布设结构的影响。探讨了GPS姿态测量系统中基线长度和天线布设结构与姿态测量精度的关系。仿真结果表明:增加航向基线长度,能够提高航向角和俯仰角的精度,增加横向基线长度,能提高横滚角的精度;当基线长度一定时,将两基线正交布设,横滚角的精度最高。  相似文献   

How many sutures in the southern Central Asian Orogenic Belt：Insights from East Xinjiang-West Gansu（NW China）？   总被引：1，自引：0，他引：1  

Wenjiao Xiao  ;Chunming Han  ;Wei Liul  ;Bo Wan  ;Ji'en Zhang  ;Song  jian Ao  ;Zhiyong Zhang  ;Dongfang Song  ;Zhonghua Tian  ;Jun Luo 《地学前缘(英文版)》2014,5(4):525-536

How ophiolitic mèlanges can be defined as sutures is controversial with regard to accretionary orogenesis and continental growth.The Chinese Altay,East junggar,Tianshan,and Beishan belts of the southern Central Asian Orogenic Belt（CAOB） in Northwest China,offer a special natural laboratory to resolve this puzzle.In the Chinese Altay,the Erqis unit consists of ophiolitic melanges and coherent assemblages,forming a Paleozoic accretionary complex.At least two ophiolitic melanges（Armantai,and Kelameili） in East Junggar,characterized by imbricated ophiolitic melanges,Nb-enriched basalts,adakitic rocks and volcanic rocks,belong to a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites,superimposed by Permian arc volcanism.In the Tianshan,ophiolitic melanges like Kanggurtag,North Tianshan,and South Tianshan occur as part of some Paleozoic accretionary complexes related to amalgamation of arc terranes.In the Beishan there are also several ophiolitic melanges,including the Hongshishan,Xingxingxia-Shibangjing,Hongliuhe-Xichangjing,and Liuyuan ophiolitic units.Most ophiolitic melanges in the study area are characterized by ultramafic,mafic and other components,which are juxtaposed,or even emplaced as lenses and knockers in a matrix of some coherent units.The tectonic settings of various components are different,and some adjacent units in the same melange show contrasting different tectonic settings.The formation ages of these various components are in a wide spectrum,varying from Neoproterozoic to Permian.Therefore we cannot assume that these ophiolitic melanges always form in linear sutures as a result of the closure of specific oceans.Often the ophiolitic components formed either as the substrate of intra-oceanic arcs,or were accreted as lenses or knockers in subduction-accretion complexes.Using published age and paleogeographic constraints,we propose the presence of （1） a major early Paleozoic tectonic boundary that separates the Chinese Altay-East Junggar multiple subduction system  相似文献   

云南省江城地区盐盆地重力勘探与深部找钾启示     

刘璎  郑绵平  于常青  张震  高磊 《中国地质调查》2014,6(6):88-97

云南省江城勐野井钾盐矿是目前我国发现的唯一固体钾盐矿。该地区地质构造复杂,近几年通过野外地质、地球物理及钻井勘探 ,认为钾盐来自深部侏罗系,并沿断裂构造带挤压塑流到表层,可能在深部还存在大面积的“盐源”。为实现找矿突破,亟须了解控制盐矿形成的构造及围岩的三维结构特征。通过对江城地区高精度重力数据位场分离、边缘检测、3D物性反演的地球物理处理与解释,获得了勐野井地区江城湖盆的基底变化、断裂展布等地质信息,确定了研究区构造格架、地下密度体的三维分布与岩盐矿的关系,推断在勐野井矿区西北深部可能还有侏罗系盐岩甚至钾盐的存在,该地区将是未来找矿工作的重点。研究成果为江城地区下一步钾盐矿勘查提供了线索和依据。  相似文献   

半潮堤前的反射形态与时均流速场分析          下载免费PDF全文

徐展  王文进  蒋学炼  杨伟超  刘俊涛 《海洋工程》2022,40(3):75-82

采用模型试验和数值模拟研究了不同水深工况下半潮堤前的反射形态及时均流速场。基于Hilbert变换建立了叠合波的时频分离技术,同时获取了入射波和反射波的波面过程及相位关系,通过试验数据证明其适用于不同反射程度的波浪信号分析。不同水深工况下,半潮堤前形成了部分立波系统,腹点和节点分别以四分之一波长的偶数倍和奇数倍交替增加。半潮堤前底床水质点水平速度包络图与波面包络图相差四分之一周期的相位,水平速度的极大值和极小值分别出现在波面包络图的节点和腹点,意味着节点处易形成冲刷,腹点处易形成淤积。3种工况的周期平均速度场均在迎浪基床上方的堤脚处存在一个小型环流系统,可能引起局部冲刷,此处需加强防护。淹没工况下,半潮堤前的周期平均速度场形成一个大型环流系统,表层水流向堤后,中下层水流向海侧,意味着底床悬起的泥沙很可能向离岸方向流失。  相似文献   

涡流发生器对潮流能水轮机翼型水动力学特性影响的数值模拟     

孙浩伟  谭俊哲  刘永辉  司先才  袁鹏  王树杰 《中国海洋大学学报(自然科学版)》2022,52(2):115-122

为了改善潮流能水轮机叶片表面流动分离问题,提高其升阻比,本文通过在潮流能水轮机叶片表面加装涡流发生器,来研究涡流发生器对潮流能水轮机水动力学性能的影响。本文以NACA4418翼型为研究对象,分别建立了含VGs和不含VGs的三维模型,利用CFD方法研究了VGs的高度、长度以及相邻一对VGs之间的间距等多个方面对该翼型性能的影响。结果表明:VGs可以有效地提高翼型的最大升力系数;相邻VGs间距的增加对流动分离的抑制有积极影响。此外,通过对尾迹区流线和旋涡的分析,进一步揭示了尾迹区的流场特征。  相似文献   

牙形石的分离方法简介   总被引：6，自引：1，他引：5  

江海水  罗根明  赖旭龙 《地质科技情报》2004,23(4):109-112

在简述牙形石的一般分离方法的基础上,重点介绍了用三溴甲烷和丙酮配制的重液来分离牙形石的实验装置、操作流程、注意事项以及重液的回收再利用;建议将重液的密度配制为2．80—2．81g／mE,这样可有效地分离出牙形石,采用自然蒸发法回收重液,处理50g样品仅损耗5mL的重液;对几种国际上曾经或正在使用的杜列液、M—45及多钨酸钠等重液的优缺点进行了简要阐述。  相似文献   

河口物质和水体长期输运分离的理论分析和观测验证Ⅰ.物质和水体长期输运分离的理论分析   总被引：3，自引：1，他引：2  

朱首贤  丁平兴  沙文钰  张文静 《海洋学报》2008,30(6)

基于单宽断面潮周期平均水体和物质对流输运通量,定义了二维水体和物质长期输运速度,它们分别描述单宽断面水体和物质长期输运的方向及快慢。通过二维水体和物质长期输运速度的对比分析,提出了物质和水体长期输运分离概念:受物质浓度影响,在物质和水体瞬时运动速度相同的情况下,物质和水体潮周期平均对流输运的方向和快慢可能存在差异。本文将二维物质长期输运速度分解为二维水体长期输运速度、二维潮泵输运速度和垂向切变输运速度,它们分别描述余流输运、潮泵输运和垂向切变输运,后两种输运造成单宽断面物质和水体长期输运分离。本文的分析表明,河口受地形、径流、潮流、密度梯度影响,存在有利于物质和水体长期输运分离的自然条件。  相似文献   

Impact of wildfire on source water contributions in Devil Creek,CA: evidence from end‐member mixing analysis     

Helen Y. Jung  Terri S. Hogue  Laura K. Rademacher  Tom Meixner 《水文研究》2009,23(2):183-200

A geochemical and end‐member mixing analysis (EMMA) is undertaken in Devil Canyon catchment, located in southern California, to further understanding of watershed behaviour and source water contributions after an acute and extensive wildfire. Physical and chemical transformations in post‐fire watersheds are known to increase overland flow and decrease infiltration, mainly due to formation of a hydrophobic layer at, or near, the soil surface. However, less is known about subsurface flow response in burned watersheds. The current study incorporates EMMA to evaluate and quantify source water contributions before, and after, a catchment affected by wildfires in southern California during the fall of 2003. Pre‐ and post‐fire stream water data were available at several sampling sites within the catchment, allowing the identification of contributing water sources at varying spatial scales. Proposed end‐member observations (groundwater, overland flow, shallow subsurface flow) were also collected to constrain and develop the catchment mixing model. Post‐fire source water changes are more evident in the smaller and faster responding sub‐basin (interior sampling point). Early post‐fire storm events are dominated by overland flow with no significant soil water or groundwater flow contribution. Inter‐storm streamwater in this smaller basin shows an increase in groundwater and a decrease in soil water. In the larger, baseflow‐dominated system, source water components appear less affected by fire. A slight increase in lateral flow is observed with only a slight decrease in baseflow. Changes in the post‐fire flow regimes affect nutrient loading and chemical response of the basin. Relatively rapid recovery of the chaparral ecosystem is evidenced, with active re‐growth and evapotranspiration evidenced by the fourth post‐fire rainy season. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

基于Barnes滤波原理的降水场客观分析及尺度分离   总被引：4，自引：0，他引：4  

毛文书  彭骏  周强  张群  苏亚麒 《成都信息工程学院学报》2008,23(6):668-672

基于Barnes滤波原理（又称高斯加权客观分析）,在进行网格点插值的同时,通过选择适当的滤波参数C、G滤去原始场中的短波噪音,使分析结果平稳光滑;另外可通过它构成一带通滤波器,根据实际需要分离出影响天气过程的各种次天气尺度,达到尺度分离的目的。以全国160个国家基准代表站1954—2006年共53a的年平均降水场为例作实例分析,并同用Grads内插函数（Oacres函数）、九点平滑函数（Smth9函数）的绘图结果进行对比分析,结果表明客观分析结果同Grads内插平滑分析结果基本相似,都能反映出我国53a年平均降水场从东南向西北逐渐递减的趋势且与实际情况相符,降水场高值中心位于长江流域及以南的华南等地区,低值中心位于黄河流域以北的广大西部地区。取不同的参数C和G得到的尺度分离后的带通滤波值,既抑止了长波,又抑制了短波,达到较好的尺度分离效果。  相似文献   

基于霍顿下渗能力曲线的流量过程线连续分割方法研究   总被引：2，自引：0，他引：2  

林凯荣  郭生练  张文华 《水文》2008,28(1):10-14

在用前期影响雨量代替流域蓄水量的基础上,提出了基于霍顿下渗能力曲线的流量过程线的连续分割方法.选择西峡、猴子岩和东湾三个流域的降雨径流资料,采用该方法对流量过程线进行分割,并与现行的数字滤波法、非线性水库法和Boussinesq方程法相比较.结果表明,该方法具有一定的物理基础、符合产汇流基本规律,而且能够减少涨洪段流量过程线分割的主观性,对于流域时段单位线和降雨径流关系的推求均有重要的意义.  相似文献