Underwater Terrain Positioning Method Based on Least Squares Estimation for AUV     

陈鹏云  李晔  苏玉民  陈小龙  姜言清 《海洋工程》2015,29(6):859-874

To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrain-matching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation (LSE) is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.  相似文献   

Hydrochemistry of the natural low pH groundwater in the coastal aquifers near Beihai,China     

Zhou  Xun  Shen  Ye  Zhang  Hua  Song  Chao  Li  Jingwei  Liu  Yan 《中国海洋大学学报(英文版)》2015,14(3):475-483

Natural weak acidic groundwater occurs in the unconfined and confined aquifers consisting of Quaternary and Neogene unconsolidated sediments near Beihai in southern Guangxi, China. Under natural conditions the groundwater has low TDS(less than 200 mg L-1) and low concentrations of trace elements(less than 100 μg L-1) with a deceasing tend in contents of the Lanthanides(rare earth elements, less than 1 μg L-1) towards higher atomic number. The groundwater ranges in p H from 3.33 to 7.0 with an average value of 5.12(even lower than that of local rainwater, 5.88). p H values in the groundwater are a bit higher in rainy seasons than those in dry seasons and do not show significant increasing or decreasing trend with time. The average p H value in groundwater in the confined aquifers is even a bit lower than that in the unconfined aquifer. Comprehensive analyses of the groundwater environment suggest that H+ in the groundwater may be derived from dissociation of H2CO3, release of the absorbed H3O+ in clay layers and the acidity of rainwater. The H2CO3 in the groundwater may be formed by dissolution of CO2(g). Minerals in the unconsolidated sediment are predominated by quartz with small amount of clay minerals. The sediments undergoing a long-term weathering contain low levels of soluble constitutes. Lack of alkaline substances in the groundwater system is also helpful in the accumulation of acidity of the groundwater.  相似文献   

基于陆态网数据低阶球谐函数电离层区域建模     

杨业  谢益炳  陆亚峰  蒋海林 《测绘信息与工程》2015,40(3)

根据高精度卫星导航和电离层活动监测的需要,特别是中国北斗系统的运营,利用陆态网络200余个GPS基准站的双频实测数据,通过建立低阶球谐函数模型同时解算电离层电子含量、GPS卫星DCB;将其结果与CODE分析中心的结果进行比较.分析表明,该方法建立的模型是可靠的,其GPS卫星DCB相对于CODE精度优于0.3ns,垂直总电子含量相对CODE精度优于3TECU.  相似文献   

Carrier phase multipath mitigation for BeiDou navigation satellite system   总被引：4，自引：1，他引：3  

Shirong Ye  Dezhong Chen  Yanyan Liu  Peng Jiang  Weiming Tang  Pengfei Xia 《GPS Solutions》2015,19(4):545-557

  相似文献   

大质量恒星形成区样本外向流的高灵敏度搜寻     

孙燕  徐烨  杨戟 《天文学报》2012,53(2):97-105

对13个大质量恒星形成区样本进行了SiO(2-1)、CH_3OH(2-1)和C~(34)S(2-1)热线的观测.在9个分子云核中,3条热线同时被探测到.这9个SiO探测中,有3个是新探测到的且它们强度都相对较弱.所有探测到的谱线都有较明显的线翼,这可能是外向流出现的证据.SiO谱线的线宽最宽,这也更进一步表明SiO辐射可能是来自高速的外向流,即更靠近外向流的激发源.估算了各分子谱线的旋转温度,柱密度和相对元素丰度.结果表明SiO和CH_3OH元素丰度之间有较好的相关性,相关系数R=0.77,但是SiO和C~(34)S元素丰度之间却没有任何相关性.  相似文献   

Paleozoic post-collisional magmatism and high-temperature granulite-facies metamorphism coupling with lithospheric delamination of the East Kunlun Orogenic Belt,NW China     

Qian Wang  Jiao Zhao  Chuanlin Zhang  Shengyao Yu  Xiantao Ye  Xiaoqiang Liu 《地学前缘(英文版)》2022,(1):96-113

Lithosphere extension and upwelling of asthenosphere at post-collisional stage of an orogenic cycle generally induce diverse magmatism and/or associated high-temperature metamorphism. Nevertheless, the intimate coexistence of post-collisional magmatic activity and high-temperature metamorphism is rare.In this contribution, a lithological assemblage composing of diverse magmatic rocks deriving from distinct magma sources and coeval high-temperature metamorphism was identified in eastern Kunlun.Petrography, ages, mineral chemistry and whole-rock geochemistry demonstrated that those intimately coexistent diverse rocks were genetically related to post-collisional extension. The garnet-bearing mafic granulites in Jinshuikou area interior of the East Kunlun Orogenic Belt are mainly composed of garnet,orthopyroxene, and plagioclase, with peak metamorphic P–T conditions of ~ 701–756 ℃and 5.6–7.0 kbar,representing a granulite-facies metamorphism at 409.7 ± 1.7 Ma. The diverse contemporaneous magmatic rocks including hornblendites, gabbros and granites yield zircon U–Pb ages of 408.6 ± 2.5 Ma,413.4 ± 4.6 Ma, and 387–407 Ma, respectively. The hornblendites show N-MORB-like REE patterns with(La/Sm)Nvalues of 0.85–0.94. They have positive zircon εHf(t) values of 0.1–4.9 and whole-rock εNd(t) values of 3.9–4.7 but relatively high(⁸⁷Sr/⁸⁶Sr)_ivalues of 0.7081 to 0.7088. These features demonstrate that the hornblendites derived from a depleted asthenospheric mantle source with minor continental crustal materials in source. As for the gabbros, they exhibit arc-like elemental signatures, low zircon εHf(t) values(-4.3 to 2.5) and variable whole-rock εNd(t) values(-4.9 to 1.2) as well as high(⁸⁷Sr/86 Sr)ivalues(0.7068 to 0.7126), arguing for that they were originated from partial melting of heterogeneous lithospheric mantle anteriorly metasomatized by subducted-sediment released melts. Geochemistry of the granites defines their strongly peraluminous S-type signatures. Zircons from the granites yield a large range of εHf(t) values ranging from -30.8 to -5.1, while the whole-rock samples yield consistent(⁸⁷Sr/86 Sr)ivalues(0.7301 to 0.7342) and negative εNd(t) values(-10.1 to -12.4). These features indicate that the S-type granites could be generated by reworking of an ancient crust. Taken together, the penecontemporaneous magmatism and metamorphic event, demonstrated the early-middle Devonian transition from crustal thickening to extensional collapse. The post-collisional mantle-derived magmas serve as an essential driving force for the high-temperature granulite-facies metamorphism and anataxis of the crust associated with formation of S-type granite. This study not only constructs a more detail Proto-Tethys evolution process of the eastern Kunlun, but also sheds new light on better understanding the intimate relationship between magmatism and metamorphism during post-collisional extensional collapse.  相似文献   

降云顶隧洞裂隙夹泥层爆破施工技术          下载免费PDF全文

李文田  刘野  刘则启 《探矿工程》2008,35(12):75-77

裂隙夹泥层对爆破施工有着较大的影响。通过降云顶隧洞爆破施工的实践,分析探讨裂隙夹泥层对爆破施工的影响及应对措施。  相似文献   

皖东北地区农村民居抗震性能调查与研究   总被引：1，自引：1，他引：1  

曹均锋  刘庆忠  叶献国  翟洪涛  冯伟栋  蒋庆  李代娣 《震灾防御技术》2011,6(2):136-145

皖东北地区位于郯庐断裂带中南段附近,具备发生中强地震的构造背景.本文基于现场调查,并结合汶川地震的震害,对该地区农村民居的结构特点、抗震能力及地震安全农居示范工程现状进行了阐述,对农村民居抗震性能的薄弱环节及对策进行了探讨,以期为该地区抗震设防工作提供参考.  相似文献   

连续运行基准站技术在大连工程测量中的应用研究     

程俊  张洪文  朱烨 《东北测绘》2012,(3):194-195,198

重点介绍了CORS技术在大连城市工程测量中的应用,分析了CORS的系统组成、工作原理和技术优势等,探讨了CORS技术在大连城市工程测量中的几个主要应用方向：工程控制测量、工程测图、规划定桩及放线、房产地籍测量和建设用地勘测定界等。与传统方法相比,该技术具有较大的优越性和广泛的应用前景。  相似文献   

东北地区“人口-经济-空间”城市化协调性研究   总被引：20，自引：6，他引：14  

孙平军  丁四保  修春亮  魏冶 《地理科学》2012,(4):450-457

城市化是一个"人口-经济-空间"三维一体的过程,其内在协调与否是城市可持续发展的关键所在。为此,首先通过构建人口、经济、空间城市化内在表征指标,运用均方差赋权法,以东北地区(指的是东北三省)34个地级市为研究对象,来综合测度其人口、经济、空间城市化水平;其次运用协调度评价模型对其协调程度进行评价;并在此基础上进行分类。研究结果表明:①东北地区经济城市化主导人口、空间城市化,但整体水平不高,平均水平基本处于加速发展阶段(0.25~0.35);②人口、经济、空间城市化水平的空间分异明显,其中人口城市化整体呈现出由北往南递减的趋势,而经济城市化则成由南往北递减的趋势,两者"内在互补(互异)"趋势非常明显;③三者城市化协调度低,且区域差异明显,由南往北递减趋势非常明显;④依据彼此间协调度主宰程度,将其划分为综合协调导向型,人口-经济、人口-空间、经济-空间协调导向型4种类型。  相似文献