基于已知特征平面的移动测量系统安置参数检校

安置误差是影响移动测量系统激光点云精度的主要因素之一。当激光点云中存在特征平面时,安置误差会导致该平面与真实平面之间产生较大的偏差,如果存在多个空间上位置关系较好的特征平面,就能够全面反映出系统的安置误差。本文以此为依据,给出了一种基于已知特征平面的移动测量系统安置参数检校方法,并详细阐述了检校场的布设、数据获取及处理等内容。实验证明,该方法是一种简单、可靠的检校方法,具有较高的实用性。     

地图学技术、科学、艺术的对立统一

随着地图学内涵和外延的扩展,认识地图学的探索从未停止。本文在现有研究对地图学认识的基础上,分析地图学的技术性、科学性与艺术性,进而探讨地图学技术性、科学性艺术的对立与统一,探索当今时代易变性影响下地图学的恒常性,从技术性、科学性、艺术性角度重新认识地图学。     

Three new species of Anthomedusae (Hydrozoa: Hydroidomedusa) from the Guangdong coastal water, China

The samples of Anthomedusae were collected from the Guangdong coastal water,China.Three new species of Anthomedusae,i.e.Zhangiella condensum Huang,Zhang et Sun,sp.nov.,Hydractinia leizhouensis Huang,Zhang et Yang,sp.nov.,and Cladosarsia simplex Huang,Zhang et Ke,sp.nov.are described.All type specimens are deposited in College of Ocean and Earth Sciences,Xiamen University.     

温室气体的卫星遥感—进展与趋势

二氧化碳和甲烷减排是控制全球增温最核心的手段,传统的人为碳排放计算主要依赖于在线监测和清单算法,2019年第49届1PCC全会明确了利用大气观测通过"自上而下"通量计算对排放清单进行支撑和验证,因此了解大气遥感碳监测发展趋势以及同化反演技术方法成为了中国应对国际气候变化事务亟待探明的重要问题.根据卫星遥感技术发展进程和...     

东亚2005年和2006年冬季风异常及其与准定常行星波活动的关系

利用NCEP/NCAR再分析资料系统地分析了2005年与2006年冬季欧亚大陆的气温和东亚冬季风的差别及其与北半球准定常波活动的关系。分析结果表明:2005年冬季欧亚大陆中、高纬度地区气温偏低,东亚冬季风偏强;而2006年冬季欧亚大陆中、高纬度地区气温偏高,出现暖冬,东亚冬季风偏弱。分析结果还表明,这两年冬季东亚冬季风的差别不仅是由于西伯利亚高压和阿留申低压的变异所造成,而且是由于北极涛动(北半球环状模)的变化所造成。并且,作者还从这两年冬季北半球准定常行星波活动的差异,在动力理论上进一步讨论了这两年冬季北半球气候和东亚冬季风差异的机理。结果表明:2005年冬季北半球行星波活动为低指数,准定常行星波在高纬度往平流层传播加强,而往低纬度对流层上层传播减弱,造成了行星波E-P通量在高纬度地区对流层中、上层辐合加强,而在副热带地区对流层中、上层辐散加强,引起了北半球高纬度地区极锋急流减弱,而副热带急流加强,这有利于西伯利亚高压的发展,从而引起了东亚冬季风增强;相反,2006年冬季北半球行星波活动为高指数,准定常行星波在高纬度往平流层传播减弱,而往低纬度对流层上层传播加强,造成了行星波E-P通量在高纬度地区对流层中、上层辐散加强,而在副热带地区对流层中、上层辐合加强,引起了北半球高纬度地区极锋急流加强,而副热带急流减弱,这不利于西伯利亚高压的发展,从而引起了东亚冬季风减弱。     

Apollo 11和嫦娥四号着陆区撞击坑退化对比分析

Apollo 11和嫦娥四号(Chang'E-4)是人类探月历史上的里程碑,它们的着陆区分别位于月球正面和背面.对两个着陆区内不同退化程度撞击坑的统计和对比分析有助于揭示研究区域的地质年龄和演化历史,对月球地质研究有着重要的意义.本文使用LRO NAC影像和DTM产品对两个着陆区附近1 km2范围内撞击坑的退化进行分析...     

水下航行体垂直出筒时水锤压力分析与研究

对航行体离筒后海水倒灌后形成的水锤效应进行了研究。 通过数据分析,描述了发射筒内产生的水锤压力现象,分析了水锤压力产生的机理,采用 CFD 分析方法对海水涌入发射筒后的流场特性和载荷特性进行了数值模拟计算;建立了水锤压力峰值估算模型,计算了航行体离筒速度和离筒时筒内压力的变化对发射筒底部压力的影响,得到不同工况条件下水锤效应的变化规律。     

2003-2016年北极净初级生产力时空变化

The area of Arctic sea ice has dramatically decreased, and the length of the open water season has increased;these patterns have been observed by satellite remote sensing since the 1970 s. In this paper, we calculate the net primary productivity(NPP, calculated by carbon) from 2003 to 2016 based on sea ice concentration products,chlorophyll a(Chl a) concentration, photosynthetically active radiation(PAR), sea surface temperature(SST), and sunshine duration data. We then analyse the spatiotemporal changes in the Chl a concentration and NPP and further investigate the relations among NPP, the open water area, and the length of the open water season. The results indicate that(1) the Chl a concentration increased by 0.025 mg/m~3 per year;(2) the NPP increased by 4.29 mg/(m~2·d) per year, reaching a maximum of 525.74 mg/(m~2·d) in 2016; and(3) the Arctic open water area increased by 57.23×10~3 km~2/a, with a growth rate of 1.53 d/a for the length of the open water season. The annual NPP was significantly positively related to the open water area, the length of the open water season and the SST.The daily NPP was also found to have a lag correlation with the open water area, with a lag time of two months.With global warming, NPP has maintained an increasing trend, with the most significant increase occurring in the Kara Sea. In summary, this study provides a macroscopic understanding of the distribution of phytoplankton in the Arctic, which is valuable information for the evaluation and management of marine ecological environments.     

Experimental,Numerical and Simplified Theoretical Model Study for Internal Solitary Wave Load on FPSO with Emphasis on Scale Effect

Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaveraged velocities induced by ISWs are used for the velocity-inlet boundary. Three scale ratio numerical models λ=1, 20 and 300 were selected, which the scale ratio is the size ratio of numerical models to the experimental model.The comparisons between the numerical and former experimental results are performed to verify the feasibility of numerical method. The comparisons between the numerical and simplified theoretical results are performed to discuss the applicability of the simplified theoretical model summarized from the load experiments. Firstly, the numerical results of λ=1 numerical model showed a good agreement with former experimental and simplified theoretical results. It is feasible to simulate the ISWs loads on FPSO by the numerical method. Secondly, the comparisons between the results of three scale ratio numerical models and experimental results indicated that the scale ratios have more significant influence on the experimental horizontal forces than the vertical forces. The scale effect of horizontal forces mainly results from the different viscosity effects associated with the model’s dimension.Finally, through the comparisons between the numerical and simplified theoretical results for three scale ratio models, the simplified theoretical model of the pressure difference and friction forces exerted by ISWs on FPSO is applied for large-scale or full-scale FPSO.     

茅山竹矿断层气定点观测场地勘选

拟在茅山断裂带沿线布设若干个断层气连续观测点,建组断层气观测网。以茅山竹矿地区为例,通过断层气测量的初步结果,结合地质、人工地震、跨断层短水准等多种手段联合分析研究区断层的活动性,从而确定断层气定点观测的点位,为组建断层气观测网的选点提供借鉴和参考。