三分量磁传感器定位模型建立及可观测性分析     

戴忠华  周穗华  单珊 《数字海洋与水下攻防》2020,3(4):295-302

针对单个三分量磁传感器的定位理论问题进行了研究，建立了单个三分量磁传感器的定位理论模型，并对系统可观测性进行了详细的理论分析。基于磁性目标的点源磁偶极子等效性，将定位过程中的目标视为匀速运动，推导得到了单个三分量磁传感器的定位理论模型。基于该定位模型，利用批量的观测数据对目标运动状态参数进行估计。对于系统可观测性问题，通过考察 Fisher 信息矩阵的奇异性，严格证明了单矢量磁传感器的定位系统的不可观测性。根据现实应用情景，推导了在部分先验条件已知下的可观测性，得到以下结论：1)单个三分量传感器定位模型是不可观测的；2)在部分先验已知的条件下，系统是可观测的。 最后，通过仿真试验验证了本文结论的正确性，为接下来采用单个三分量传感器对汽车、水面舰艇等一些低动态运动目标的跟踪提供了重要的理论依据。  相似文献   

基于预报钟差的轨道快速恢复     

陈倩  陈俊平  吴杉  张益泽  于超 《测绘学报》2020,49(1):24-33

我国北斗卫星导航系统由GEO/IGSO/MEO混合星座构成,基本每7~10 d就会有一颗GEO卫星或IGSO卫星进行轨控操作。从卫星轨控开始,卫星存在5~6 h的不健康时期。造成机动卫星长期不健康的关键因素之一在于卫星和测站钟差数据的积累周期较长。本文提出了一种基于预报钟差的轨道快速恢复算法,通过结合星钟和站钟预报压缩机动卫星定轨观测数据积累的时间,从而缩短卫星恢复所需时间。6组机动试验结果表明:采用预报钟差策略在快速恢复初期的前几个小时对轨道预报的贡献尤为显著,对第1组定轨URE预报贡献最大可达84.82%。从3~8 h期间6组定轨平均情况来看,采用优化策略的预报URE,C01平均降低了26.06%,C04平均降低了31.58%,C03降低了9.95%。经测试该方法至少能将卫星不可用时间压缩1 h,对北斗系统建设具有重要工程应用价值。  相似文献   

Effects of different land use types on potential evapotranspiration in the Beijing-Tianjin-Hebei region,North China     

Han  Jingyan  Zhao  Yong  Wang  Jianhua  Zhang  Bing  Zhu  Yongnan  Jiang  Shan  Wang  Lizhen 《地理学报(英文版)》2019,29(6):922-934

Journal of Geographical Sciences - Potential evapotranspiration (ET0) is vital for hydrologic cycle and water resource assessments as well as crop water requirement and irrigation demand...  相似文献   

Multi-parameter Analysis of Local Singularity Mapping and Its Application to Identify Geochemical Anomalies in the Xishan Gold Deposit,North China     

Xu  Shan  Hu  Xiangyun  Carranza  Emmanuel John M.  Wang  Gongwen 《Natural Resources Research》2020,29(6):3425-3442

Natural Resources Research - Identification of geochemical anomalies from geological background is of great significance in the exploration of complex mineralization systems. For a 2D problem, the...  相似文献   

Cropland physical disturbance intensity: plot-scale measurement and its application for soil erosion reduction in mountainous areas     

Ming Li  Yu-kuan Wang  Pei Xu  Bin Fu  Cong-shan Tian  Shan Wang 《山地科学学报》2018,15(1):198-210

Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation. Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers’ management behavior. The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity (CLDI) to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas. The study was based on both plot survey and household interview data, collected from six typical catchments in mountainous areas of southwestern China. Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index. The rough set theory was referenced to avoid subjectivity during weight allocation. The results show that conventional tillage, deep fertilization, and manual weeding are the main causes of cropland soil erosion, whereas manure application in combination with seasonal fallow reduces soil erosion. Different crop types as well as cropland location factors determine the spatial pattern of CLDI. Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI, and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance. These results are critical to help better protect rural environments in mountainous areas. Based on the results, methods to reduce cropland soil erosion are suggested.  相似文献   

极地预报年及相关科学问题     

姜珊  杨清华  孙启振  李春花  张林  滕骏华 《海洋学报》2018,40(11):157-165

为有效应对全球气候变化和极地增暖挑战，世界气象组织（WMO）于2013年启动了"极地预报计划"（PPP，2013-2022年），并于2017年启动了PPP的核心行动"极地预报年"（YOPP，2017年中期至2019年中期）。本文对"极地预报计划"和"极地预报年"的相关情况进行了介绍，重点说明了该研究项目支撑下在社会效益、检验、观测、模拟、资料同化、集合预报、可预报性和诊断、全球关联8个领域需要解决的科学问题和开展的工作。同时，探讨了我国借PPP/YOPP实施契机，在极地现场观测、数值预报和信息服务方面需要做出的努力。  相似文献   

风暴潮淹没范围确定方法与应用——以台风“玛莉亚”风暴潮为例          下载免费PDF全文

贾宁  陶荣幸  石先武  高廷  戴悦  刘珊  刘强 《海洋开发与管理》2018,35(12):8-10

确定风暴潮淹没范围是风暴潮灾害损失评估工作的核心内容。为提高海洋灾害调查水平,全面掌握灾害影响情况和制定灾害应对措施,文章梳理确定风暴潮淹没范围的主要方式,即遥感和现场调查;重点介绍现场调查手段的4种确定方法,即通过淹没痕迹、漂浮物聚集位置、植被变化和现场询问确定,并分别提出调查结果的可靠性判定方法;以2018年第8号台风"玛莉亚"造成的风暴潮淹没影响为实例,综合采用查找淹没痕迹、查找漂浮物聚集位置和现场询问3种方法,确定牙城镇风暴潮的淹没范围约为91.7万m2。研究结果表明:与采用遥感手段确定淹没范围相比,现场调查结果更具准确性和科学性,可适用于小规模淹没范围的确定,相关方法可行有效。  相似文献   

In situ observations of wave pumping of sediments in the Yellow River Delta with a newly developed benthic chamber     

Shaotong Zhang  Yonggang Jia  Yaqi Zhang  Xiaolei Liu  Hongxian Shan 《Marine Geophysical Researches》2018,39(4):463-474

A specially designed benthic chamber for the field observation of sediment resuspension that is caused by the wave-induced oscillatory seepage effect (i.e., the wave pumping of sediments) is newly developed. Observational results from the first sea trial prove that the geometry design and skillful instrumentation of the chamber well realize the goal of monitoring the wave pumping of sediments (WPS) continuously. Based on this field dataset, the quantitative contribution of the WPS to the total sediment resuspension is estimated to be 20–60% merely under the continuous action of normal waves (H_s ≤ 1.5 m) in the subaqueous Yellow River Delta (YRD). Such a large contribution invalidates a commonly held opinion that sediments are purely eroded from the seabed surface by the horizontal “shearing effect” from the wave orbital or current velocities. In fact, a considerable amount of sediments could originate from the shallow subsurface of seabed driven by the vertical “pumping effect” of the wave-generated seepage flows during wavy periods. According to the new findings, an improved conceptual model for the resuspension mechanisms of silty sediments under various hydrodynamics is proposed for the first time.  相似文献   

藻类类胡萝卜素合成通路基因的系统发育分析     

王珊珊  张磊  池珊  王国良  王绪敏  刘涛  唐学玺 《海洋学报(英文版)》2018,37(4):89-101

  相似文献   

热带西太平洋Y3和M2海山区网采浮游植物群落结构特征     

郭术津  孙晓霞  郑珊  罗璇  朱明亮  梁俊华 《海洋科学》2018,42(10):31-40

研究了热带西太平洋雅浦Y3海山冬季和马里亚纳M2海山春季网采浮游植物群落结构,对调查区浮游植物的物种组成、优势种类、细胞丰度以及多样性指数进行了分析。结果表明,两个海山区共鉴定浮游植物4门50属219种,其中硅藻门30属106种,甲藻门17属112种,蓝藻门1属2种,金藻门2属3种。两个航次研究区浮游植物优势种均以链状硅藻如根管藻(Rhizosolenia)、半管藻(Hemiaulus)和角毛藻(Chaetoceros)等属的种类为主,此外太阳漂流藻(Planktoniella sol)、铁氏束毛藻(Trichodesmium thiebautii)以及部分角藻(Ceratium)物种优势度也比较明显。Y3海山区浮游植物细胞丰度介于1.60～16.61 cells/L,平均值为5.02 cells/L; M2海山区浮游植物细胞丰度介于1.36～10.20 cells/L,平均值为4.12cells/L。两个海山区浮游植物细胞丰度的分布趋势均受硅藻影响较大,甲藻细胞丰度相对较低。在属的水平上,角毛藻、根管藻、角藻和半管藻等属的细胞丰度对两个海山区浮游植物总细胞丰度的贡献较大。多样性指数方面, Y3海山区浮游植物群落香农-威纳指数H′(shannon-wiener index)介于3.95～4.69,平均值为4.30; M2海山区浮游植物群落香农-威纳指数介于3.23～4.46,平均值为3.83。两个海山区浮游植物群落多样性指数均处于较高水平,但站位间的变化不明显。目前,关于热带西太平洋海山区浮游植物群落结构的研究还非常缺乏,亟需后续研究的补充。  相似文献