基于卡尔曼滤波的船舶轨迹异常行为快速检测方法

基于全球船舶自动识别系统(Automatic Identification System,AIS)数据的船舶轨迹异常行为快速检测对于保障船舶航行安全、辅助安全监管具有重要意义.AIS数据具有容量大、更新频率快的特点,而当前AIS轨迹异常行为检测方法依赖于大量的训练样本与历史数据,实用性与普适性较差,难以用于船舶轨迹异常行为快速检测.为此,本文定义了船舶追踪、航速、航向、位置4种异常行为检测模型,提出了一种基于卡尔曼滤波的船舶AIS轨迹异常行为检测方法,实现了船舶AIS轨迹的异常行为快速检测与报警.实验选取经过我国东海部分地区3天的AIS数据,对实验结果的正确性与耗时进行分析,结果表明模型可以满足异常即时发现、即时处理的应用需求.     

双核型空间结构模式的探讨

双核型空间结构被定义为由港口城市与区域中心城市及其连结组成，这是分布于我国临海沿江地区较为普遍的空间结构现象，对其深入了解剖有助于使发展轴的确定更趋严谨化和科学化。     

A novel method for simultaneous analysis of particle size and mineralogy for Chang’E-5 lunar soil with minimum sample consumption

Science China Earth Sciences - The successful return of lunar soil samples from the northern Oceanus Procellarum by the Chang’E 5 (CE-5) mission has provided unprecedented ground-truth...     

基于生成树的控制网最小独立异步环搜索方法研究

实现控制网最小独立异步环的计算机自动搜索是一项较为复杂、繁琐的工作,目前介绍此工作方法的文献大多是阐述过程中的某一部分,并且部分细节问题讨论得较少。文中以帮助初学者对此项工作形成完备的认识并能够自主编程实现为目的,以GNSS控制网为例,详细介绍基于生成树的控制网最小独立异步环自动搜索方法,内容包括生成树的定义及建立方法,最短路径搜索-Dijkstra算法的原理与实现步骤,利用生成树与最短路径搜索算法搜索最小独立闭合环的原理及具体实现步骤,以及同步观测环的自动搜索方法。最后以一个控制网实例说明此方法的可行性。     

经济地理区位分析的思路与方法——以江苏省灌河口地区为例

作为地理学的入门性技术方法,经济地理区位分析无论是基本含义还是应用,无论是定性分析还是定量建模.都有大量的成果问世,已达到相对成熟的研究阶段.但灌河口的案例分析事实上昭示出了经济地理区位分析的新思路.本文将其归纳为经济地理区位分析的综合集成法,其基本含义是多时空尺度、多影响要素的综合集成分析.即不仅仅将经济地理区位静态地理解为一种相对位置关系.而是在考虑区位与其影响因素之间相互关联的过程中进行经济地理区位的综合性分析,具体包括多要素综合分析法则、多尺度时空分析法则和多路径门户分析法则.在此基础上进一步建构了经济地理区位分析的理论框架,试图对经济地理区位(分析)这一地理学最为基本的知识、理论与方法,进行有一定新意的理论与方法论探讨.     

加筋土动弹性模量的动三轴试验研究

采用动三轴试验系统对加筋土试样进行固结不排水三轴剪切试验。研究了在不同加筋材料、不同加筋层数、不同围压、不同固结应力比条件下的加筋土的动弹性模量变化规律,并与素土试样试验结果进行对比。研究结果表明,加筋土的动弹性模量随围压和固结应力比的增加而增大,窗纱加筋试样的最大动模量相比素土有了较大的提高,并随着加筋层数的增加而增大,土工布加筋土试样最大动弹模量与素土的最大动弹模量增减趋势不明确。     

关于李四光教授往事的回忆

李四光先生是我国老一辈地质学家之一,对地质学的许多分支学科作出了重要贡献。他建立了地质力学,并以发现中国第四纪冰川而闻名于世。我对1933年11月他在中国地质学会第十届年会上关于庐山第四纪冰川的理事长演说至今记忆犹新。作为一个科学家,他强调一个地质工作者首先要做好野外工作,一切地质假说和理论必须以事实为依据。作为新中国的第一任地质部部长,他鼓励地质工作者要为祖国的社会主义建设作出贡献。     

Theoretical studies on penetration resistance of suction caissons in clay

ABSTRACT

The suction caisson is commonly a top-closed cylindrical steel structure with large diameter, short length and much thinner skirt wall thickness. The resistance to penetrating is calculated as the sum of the tip bearing capacity and the adhesion on the both sides of the skirt wall. Since the thickness of the skirt wall is very small, the downward adhesion produced by the skirt wall will cause the additional vertical stress and shear stress in the soil at the skirt tip level, increasing the skirt tip resistance. However, the increase in skirt tip resistance caused by the additional vertical stress rather than shear stress in soil at the skirt tip level was only considered, this may lead to an inaccurate estimation for the tip bearing capacity and the suction required. Thus, a modified slip-line field is put forward in this study to estimate the tip resistance. The expression of obtaining the minimum suction to install the suction caisson in clay is derived in terms of the force equilibrium. Results from calculations of the minimum suction have been proved to be in a good agreement with the measured data.     

辽西地区九佛堂组及其珍稀化石层划分与对比

辽西地区是世界重要的化石产地,中生界下白垩统九佛堂组是该地区重要的含化石层位,含有著名的热河生物群化石。通过对辽西地区九佛堂组诸多剖面的综合研究及化石组合对比,将辽西地区九佛堂组划分为3个岩性段,并整理完善了辽西九佛堂组珍稀化石层序列。根据对辽西九佛堂组珍稀化石层进行的对比研究,建立了肖台子层、报马营子层、西营子层等3个珍稀化石层,并分析了珍稀化石层岩性特征,认为珍稀化石层的形成与火山活动存在直接关系,首次提出辽西九佛堂期存在火山活动。     

Formation of an anticyclonic eddy and the mechanism involved: a case study using cruise data from the northern South China Sea

Data from satellite altimetry and in situ observations together with the Hybrid Coordinate Ocean Model (HYCOM) reanalysis data were used to investigate the mechanism and formation of an anticyclonic eddy in the northeastern South China Sea (SCS). Analysis of water mass using cruise data indicated that the water captured in the eddy diff ers from those in the SCS, the Kuroshio intrusion, and the eddy-forming region. Data from sea surface height (SSH) and sea level anomaly (SLA) indicate that the eddy formed due both to the Kuroshio intrusion and the local circulation in the SCS. The Kuroshio intrusion is present at the start of the eddy growth (March 5-9) before Kuroshio leaps the Luzon Strait. The eddy then becomes larger and stronger in the absence of the Kuroshio intrusion. From the eddy budget of the HYCOM reanalysis data, the formation of the eddy goes in three steps. By the third step, the eddy had become aff ected by variations of local SCS circulation, which is more strongly than in the fi rst step in which it is aff ected more by the Kuroshio intrusion. The variability of the temperature and salinity inside the eddy provide a support to this conclusion. The water in the SCS intruded into the eddy from the southeast, which decrease the salinity gradually in the southern part of the eddy during the growth period.