内点最大化与冗余点控制的无人机遥感图像配准     

余蕊  陈玮扬  杨扬  杨昆  罗毅 《遥感学报》2020,24(11):1325-1341

利用小型无人机进行遥感图像配准在自然灾害损害评估、环境监测和目标检测与追踪等领域发挥着至关重要的作用，但小型无人机的图像采集过程容易受风速/风向、复杂地形、电池容量、飞行姿态、飞行高度等自然或人为因素的影响。这些问题通常会导致捕捉到的场景重叠率低与图像非刚性畸变，在特征点提取过程中产生大量冗余点，增加了图像配准的难度。本文提出一种基于特征点的小型无人机图像配准方法，该方法的核心思想是在配准过程中识别冗余点，同时最大化可用内点数量。所识别的冗余点当作控制点，用于控制网格代图像的运动。最后通过最大化内点和合理移动控制点来恢复图像变换。本文使用50对小型无人机图像进行特征匹配和图像配准的实验，其中平均配准精度可达80.38%，并且本文方法在所有的情况下都优于5种当前流行算法。  相似文献   

变荷载下双层地基一维非线性固结近似解析解     

江留慧  李传勋  杨怡青  张锐 《岩土力学》2020,41(5):1583-1590

目前考虑土体非线性压缩及渗透特性的双层地基非线性固结解均假定土体固结系数保持不变，能反映固结系数变化的双层地基非线性固结解还很鲜见。引入经典的e- 和e- 非线性关系描述土体的非线性压缩、渗透特性，在假定双层地基上、下土层压缩指数与渗透指数比值 相等且不等于1的基础上，得到变荷载下考虑土体固结系数变化的双层地基一维非线性固结近似解。该解答在 1条件下可退化为已有的 1时双层地基一维非线性固结解。基于此解探讨了双层地基上、下土层参数的相对比值对非线性固结性状的影响。结果表明：单面排水条件下 越小，下层土与上层土的相对压缩性越低、相对渗透性越高，则双层地基非线性固结速率越快；减小 值，增加双层地基中压缩性小、渗透性高的土层的厚度，会加快地基的固结速率。  相似文献   

2018?2019年舟山近海浮游动物群落结构春季年际变化及其与水团的关系   总被引：1，自引：1，他引：0  

王慧君  许永久  俞存根  章寒  张洪亮  蒋日进  梁君  郭爱  朱文斌  徐开达  刘连为  王皓学 《海洋学报》2020,42(6):90-100

根据2018?2019年春季两个航次在舟山近海进行的浮游生物调查结果，对舟山近海的浮游动物群落结构(类群组成、优势种数量)年际变化进行了研究，利用典范对应分析(Canonical Correspondence Analysis, CCA)研究了两年春季浮游动物类群组成差异、优势种变化的原因，初步探讨了春季浮游动物群落结构动态变化的机制。结果表明:根据表层温度(Sea Surface Temperature，SST)、表层盐度(Sea Surface Salinity，SSS)的聚类分析，将该区域分为3个水团:杭州湾内水团(I区)、舟山本岛上升流水团II区)、舟山近海水团(III区)。不同水团对浮游动物类群组成影响显著，引起2018年和2019年春季3个水团区差异的主要贡献种(贡献率>10%)均为中华哲水蚤，同一水团两年间年际差异的贡献种如下:I区为捷氏歪水蚤(56.91%)和真刺唇角水蚤(12.34%)；II区为中华哲水蚤(72.64%)、五角水母(13.35%)；III区为中华哲水蚤(41.93%)、夜光虫(22.94%)。CCA分析表明，第1 CCA轴(CCA1)和第2 CCA轴(CCA2)共解释了两年春季浮游动物优势种累计方差的46.14%和物种?环境累计方差的97.82%。CCA1主要反映了空间(近海水团和湾内水团)的差异。CCA2主要反映了2018年和2019年站位的年际差异。盐度是影响春季浮游动物群落结构空间差异的主要因素，而温度、叶绿素a浓度是春季浮游动物群落结构年际差异的主要因素。  相似文献   

利用GPS拖体在万山区域测量平均海面技术研究     

翟万林  朱建华  马超飞  樊小慧  闫龙浩  王贺  陈春涛 《海洋学报(英文版)》2020,42(5):123-132

Wanshan area has been chosen to be the specified field to calibrate and validate(Cal/Val) the HY-2 altimeter and its follow-on satellites. In March 2018, an experiment has been conducted to determine the sea surface height(SSH) under the HY-2 A ground track(Pass No. 203). A GPS towing-body(GPS-TB) was designed to measure the SSH covering an area of about 6 km×28 km wide centered on the HY-2 A altimeter satellite ground track. Three GPS reference stations, one tide gauge and a GPS buoy were placed in the research area, in order to process and resolve the kinematic solution and check the precision of the GPS-TB respectively. All the GPS data were calculated by the GAMIT/GLOBK software and TRACK module. The sea surface was determined by the GPS-TB solution and the tide gauge placed on Zhiwan Island. Then the sea surface of this area was interpolated by Arc GIS10.2 with ordinary Kriging method. The results showed that the precision of the GPS-TB is about 1.10 cm compared with the tide gauge placed nearby, which has an equivalent precision with the GPS buoy. The interpolated sea surface has a bias of –1.5–4.0 cm with standard deviation of 0.2–2.4 cm compared with the checking line. The gradient of the measured sea surface is about 1.62 cm/km along the HY-2 orbit which shows a good agreement compared with the CLS11 mean sea surface(MSS). In the Cal/Val of satellites, the sea surface between the tide gauge/GPS buoy and the footprint of altimeter can be improved by this work.  相似文献   

SMAP卫星海表盐度产品的检验与校正     

秦思思  王辉  朱江  万莉颖  张宇  王昊运 《海洋学报(英文版)》2020,39(3):148-158

In this study, sea surface salinity(SSS) Level 3(L3) daily product derived from soil moisture active passive(SMAP)during the year 2016, was validated and compared with SSS daily products derived from soil Moisture and ocean salinity(SMOS) and in-situ measurements. Generally, the root mean square error(RMSE) of the daily SSS products is larger along the coastal areas and at high latitudes and is smaller in the tropical regions and open oceans. Comparisons between the two types of daily satellite SSS product revealed that the RMSE was higher in the daily SMOS product than in the SMAP, whereas the bias of the daily SMOS was observed to be less than that of the SMAP when compared with Argo floats data. In addition, the latitude-dependent bias and RMSE of the SMAP SSS were found to be primarily influenced by the precipitation and the sea surface temperature(SST). Then, a regression analysis method which has adopted the precipitation and SST data was used to correct the larger bias of the daily SMAP product. It was confirmed that the corrected daily SMAP product could be used for assimilation in high-resolution forecast models, due to the fact that it was demonstrated to be unbiased and much closer to the in-situ measurements than the original uncorrected SMAP product.  相似文献   

论渔业法之未取得或违反船网工具指标造船违法行为的法律责任          下载免费PDF全文

曲芮  裴兆斌  郭云峰 《海洋开发与管理》2020,37(3):12-15

船舶是渔业生产、水上运输的重要工具，我国对渔业船舶借助船网工具控制指标管理模式达到对渔船数量和功率数控制的“双控”管理，但实践中碍于很多因素还存在未取得或违反船网工具指标造船的现象，这一行为对水域交通安全、渔业生产安全、渔业资源保护3个方面都存在安全隐患。文章主要梳理现行法律法规对这一行为的规定并简要分析其法律责任，建议在处罚幅度中增加处罚下限。  相似文献   

粤港澳大湾区海洋经济创新发展研究          下载免费PDF全文

谢凡  张锐 《海洋开发与管理》2020,37(6):65-69

海洋经济创新发展对粤港澳大湾区创新驱动、打造具有国际竞争力的科技创新中心具有重要意义。文章介绍粤港澳大湾区当前的海洋经济创新发展情况及其优势和不足，从构建大湾区海洋创新发展产业链、驱动陆海科技创新一体化、完善科技创新驱动体制机制和推动科技金融服务蓝色经济发展等方面，提出粤港澳大湾区海洋经济创新发展的突破要点和路径。  相似文献   

导管架平台拆除过程稳定性及影响因素分析     

孙树峰  吕涛  陈国明  孙久洋  宋玉东  何睿 《海洋工程》2020,38(1):140-146

现有服役海洋平台正逐步走向老龄化,海洋平台拆除成为海洋工程新的经济增长点。针对达到服役年限的导管架平台,基于数值分析方法模拟拆除过程,开展平台在不同拆除阶段和环境载荷等参数下的稳定性及影响规律研究。基于钢结构整体稳定性理论,以导管架平台拆除过程中顶点位移为参考,定义导管架平台拆除作业稳定性指标,提出拆除作业阶段划分方法,通过分析导管架平台在不同影响因素作用下拆除过程稳定性响应,给出拆除作业建议。选取我国南海某4裙12腿进行实例分析,结果表明:主桩腿对导管架平台起决定性承载作用,拆除部分主桩腿后需要引入外部支撑力,以保证拆除作业安全进行;拆除构件越多,来浪方向和环境载荷大小对平台影响越加显著。研究结果可为导管架平台拆除作业提供参考。  相似文献   

Flexural performances of prestressed high strength concrete piles reinforced with hybrid GFRP and steel bars     

Ping Wu  Yang Guo  Dayong Zhu  Weiliang Jin  Zhenhua Zhang  Rongzhu Liang 《Marine Georesources & Geotechnology》2020,38(5):518-526

Abstract

This study developed prestressed high-strength concrete (PHC) piles reinforced with high-strength materials (glass fiber-reinforced polymer (GFRP) bars) for flexural performance enhancement. Flexural strengths and behaviors of PHC piles reinforced with hybrid GFRP and steel bars were experimentally investigated, respectively. Large-scale specimens with total lengths of 12,000?mm and diameters of 600?mm were constructed and tested under bending, accompanied by evaluation of effects of non-prestressed reinforcement type and longitudinal reinforcement ratio. J-factors were calculated to evaluate deformability of all the specimens. PHC piles reinforced with GFRP bars were demonstrated to have much higher flexural capacity than those reinforced with steel bars. Moreover, strains at the midspans of cross sections of all the specimens basically conformed to the assumption of plane section. Failure of PHC piles reinforced with GFRP bars was attributable to gradual concrete crushing, while that of PHC piles reinforced with steel bars resulted from steel yielding. Results of this study were expected to provide theoretical basis for wide engineering applications of PHC piles reinforced with hybrid GFRP bars and steel bars in marine structures.  相似文献   

微塑料对海洋桡足类摄食、排泄及生殖的影响     

于娟  许瑞  魏逾杰  田继远  王雪丹  来敬广  陈容  杨桂朋  张正雨  邵云粹 《中国海洋大学学报(自然科学版)》2020,50(3):73-80

微塑料污染目前成为海洋污染普遍关注的一个研究热点。本文在实验室内将青岛近海常见的海洋桡足类猛水蚤暴露于不同浓度的微塑料尼龙6中,研究了猛水蚤的摄食、排泄以及生殖的变化。研究结果表明,微塑料尼龙6对猛水蚤的摄食、排泄、生殖均产生不利的影响,并且存在剂量-效应关系。微塑料尼龙6对猛水蚤摄食率、滤水率、排粪率的24 h·EC 50分别为67.7、62.2、84.1 mg·L^-1,对猛水蚤抱卵率的144 h·EC 50为30.3 mg·L^-1。“饱食感”造成猛水蚤摄食率降低,从而能量和营养摄入不足可能是导致猛水蚤抱卵率降低的原因。猛水蚤对微塑料的摄食,导致猛水蚤排泄的粪便颗粒小型化,由长椭球体变为短小椭球体,可能与其粘度或物理结构的改变有关。暴露于尼龙6的猛水蚤的粪便体积和沉降速率显著低于未暴露微塑料的对照组。本实验结果对于研究微塑料对海洋桡足类以及滤食性浮游动物的生态毒理影响具有一定的帮助。  相似文献