对研学旅行基础能力建设的探索     

钟业喜  吴筱恬  熊小英  鞠民 《地理教学》2019,(10):41-43,49

研学旅行作为一种新型的"研学"和"旅行"的教育活动,近些年发展迅速并拥有了广大的市场需求,但与此同时研学旅行基础能力建设的不足也逐渐显露。笔者在对研学旅行研究意义和发展现状阐述的基础上,总结了现阶段研学旅行基础能力建设中的问题,包括研学标准体系不完善,难以管理和规范研学市场;研学人才队伍良莠不齐,缺乏专业化师资队伍;研学基地类型少,基础设施建设不健全。并且从标准建设、师资建设和基地遴选及建设方向对研学旅行基础能力提升提出了建议。  相似文献   

一种快速非局部平均合成孔径雷达海洋图像斑点噪声抑制方法     

查国震  许德伟  杨燕明  宋新改  钟福煌 《海洋学报(英文版)》2019,38(11):140-148

合成孔径雷达在海洋环境监测和海洋研究中扮演着越来越重要的角色。受其成像机制的影响,合成孔径雷达图像总是受到斑点噪声的污染。斑点噪声的存在会增大目标识别、跟踪和分类的难度,也会降低雷达信号的信噪比。合成孔径雷达海洋图像具有一些特殊的性质：海洋现象在雷达图像中主要呈现为条带状或斑块状的结构。这些条带状或斑块状的结构呈现出高度的自相似性或信息冗余。非局部平均方法能够衡量图像中不同图像块之间纹理结构的相似性,并利用图像的自相似性对图像进行去噪。但非局部平均去燥方法存在计算量巨大、计算耗时长的缺点,这几乎限制了其实际应用。本文采用一种自适应方法将雷达图像中的像素点区分为纹理区像素点和平坦区像素点。对纹理区像素点,采用较大的相似窗和搜索窗,对平坦区像素点,采用较小的相似窗和搜索窗,从而提高计算速度。进一步,本文基于计算统一设备并行架构（CUDA）技术,利用计算机图形处理器（GPU）对前述算法进行并行加速。与经典非局部平均算法相比,加速后算法的计算效率提高了200倍。  相似文献   

潮汐河口环流、湍流、混合与层化的物理学          下载免费PDF全文

时钟  熊龙兵  倪智慧  李霞 《海岸工程》2019,38(1):1-31

简要回顾了潮汐河口环流、湍流、混合与层化的基本物理概念、内涵、研究方法、研究成果,指出了主要的研究进展,最后,展望了今后的研究方向。本文不考虑悬沙和风浪的影响。经典的河口环流也因潮汐应变的出现而受到挑战,河口环流由重力环流和潮汐应变环流构成。"涡黏度-剪切协方差(ESCO)"概念的提出,又区分出重力ESCO环流与潮汐ESCO环流。横向环流,尤其具有曲率的弯道中的横向环流,也得到进一步的理解。涡度方法的应用,揭示横向环流不仅由各种不同物理机制造成,而且对纵向河口重力环流有重要的影响。分层流中剪切湍流的理论加深了人们对潮汐河口湍流、混合的物理学的认识,势能差异方程更是使得定量理解潮汐河口混合与层化的三维时间、空间变化成为可能。  相似文献   

基于WebGIS的GIS网络虚拟实验室建设     

魏东琦  郭明强  黄颖  吴亮  谢忠 《测绘工程》2019,28(5):35-38

虚拟实验室是高校教学改革的重点方向之一,WebGIS技术完全可以将传统桌面GIS软件上机操作过程中的各个功能移植到Web客户端中。基于WebGIS技术,设计一个基于REST服务和Ajax客户端的GIS网络虚拟实验室,重点研究GIS网络虚拟实验室的系统体系架构,对虚拟实验室中的各个组成部分和功能进行设计,设计的GIS网络虚拟实验室能够提高学生上机实验过程中的学习兴趣和积极性,提高GIS上机实验教学效率和教学质量,为其它同类课程建设网络虚拟实验室提供技术参考。  相似文献   

Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015   总被引：1，自引：0，他引：1  

Denghui Li  Meng Zhou  Zhaoru Zhang  Yisen Zhong  Yiwu Zhu  Chenghao Yang  Mingquan Xu  Dongfeng Xu  Ziyuan Hu 《中国海洋大学学报(英文版)》2018,17(3):477-486

The northern slope region of the South China Sea(SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by cross-shelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55-m water masses on the SCS northern slope and thereby elucidate the cross-slope transport of shelf water(SHW) and the intrusions of Kuroshio water(KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water(SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong cross-slope current with speeds greater than 50 cms~(-1) to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area.  相似文献   

Sea State Bias Estimation with Least Absolute Shrinkage and Selection Operator (LASSO)     

Guoqiang Zhong  Benxiu Liu  Yingting Guo  Hongli Miao 《中国海洋大学学报(英文版)》2018,17(5):1019-1025

With the sea-level rising, the measurement of sea surface height (SSH) is attracting more and more attention in the area of oceanography. Satellite radar altimeter is usually used to measure the SSH. However, deviation between the measured value and the actual one always exists. Among others, the sea state bias (SSB) is a main reason to cause the deviation. In general, one needs to estimate SSB first to correct the measured SSH. Currently, existing SSB estimation methods more or less have shortcomings, such as with many parameters, high prediction error and long training time. In this paper, we introduce an effective and efficient linear model called LASSO to the SSB estimation. The LASSO algorithm minimizes the residual sum of squares under the condition that the sum of the absolute values of each coefficient is less than a certain constant. In the implementation of LASSO, we use the significant wave height and wind speed to fit the LASSO model. Hence, the applied model has only 3 parameters, corresponding to the two inputs and a bias. Experimental results on the data of JASON-2, JASON-3, T/P and HY-2 radar altimetry show that LASSO performs better than geophysical data records (GDR) and ordinary least squares (OLS) estimator. Moreover, from the running time, we can see that LASSO is very efficient.  相似文献   

Analysis on Link Between the Macroscopic and Microscopic Air–Water Properties in Self-Aerated Flows     

Wang-ru Wei  Wei-lin Xu  Jun Deng  Zhong Tian  Fa-xing Zhang 《中国海洋工程》2018,32(5):614-623

Self-aeration in high-speed free surface flows occurs commonly and is of interest to ocean engineering, hydraulic engineering, and environmental engineering. For two-phase air–water flows, macroscopic air–water flow properties develop gradually, accompanied by the change of microscopic air–water structures. In this article, representational experimental studies on macroscopic and microscopic characteristics of self-aerated open-channel flows are summarized and compared. The isolated effect of the flow Reynolds number and air quantity on the differences in air count rate and chord size are analyzed and discussed. The results show that the characterized flow depth y₅₀, affected by the turbulence transfer, is a specific criterion to distinguish the interior air–water structure development. Two distinct linear trends of self-aeration are found, depending on the y₅₀/y₉₀ variation with a breaking point at C_mean = 0.50. The air count rate and size scale in self-aerated flows are affected by the air quantity of self-aerated flows, even with identical flow Reynolds numbers. Thus, a specific parameter is proposed to assess the air–water structures and a series of self-similarity relationships in self-aeration properties are obtained. The link between macroscopic and microscopic air–water properties results in significant scale effect on air–water structures in self-aerated flows.  相似文献   

“21世纪海上丝绸之路”的海洋环境研究——印度洋海表风速变化趋势          下载免费PDF全文

许跃  郑崇伟  张仲  田妍妍  张哲  杨文广 《海洋开发与管理》2018,35(2):78-81

文章利用ERA-40海表10m风场,采用一元线性回归方法,计算印度洋海表风速在45年间(1957年9月至2002年8月)的逐年变化趋势,为"21世纪海上丝绸之路"建设、海上风能开发和全球气候变化研究等提供科学依据。研究表明:海表风速呈显著性逐年递增的区域主要分布于25°S—10°N的海域和南半球咆哮西风带所控制的海域,递增趋势为0.01~0.035m·s-1·a-1,仅零星海域呈显著性递减趋势,其余海域的海表风速无显著变化趋势;南、北印度洋的海表风速分别以0.010 2m·s-1·a-1和0.004 7m·s-1·a-1的速度显著性逐年线性递增,年平均海表风速分别在7.5m·s-1左右和5.2m·s-1左右;南、北印度洋存在共同的2.6~2.7a和5.2a的变化周期以及26a以上的长周期变化,且海表风速的突变期分别为1989年和1978—1980年。  相似文献   

基于线粒体DNA D-loop序列的黄斑篮子鱼群体遗传多样性分析     

黄小林  李文俊  林黑着  杨育凯  李涛  虞为  黄忠 《热带海洋学报》2018,37(4):45-51

对中国华南沿海不同地理群体的黄斑篮子鱼(Siganus oramin)进行遗传多样性分析, 测定了漳州东山湾(DS)、深圳大亚湾(DY)、深圳大鹏湾(DP)、阳江沙扒湾(SB) 4个群体共计100尾黄斑篮子鱼线粒体DNA D-loop序列。结果显示: 序列长度约828bp, 包含72个变异位点, 50个单倍型, A、T、C、G含量平均为31.2%、31.1%、20.8%和16.9%; 单倍型多样性指数为0.893±0.053~0.957±0.030, 核苷酸多样性指数为0.0105±0.0031~0.0179±0.0031, 表现为高单倍型多样性而低核苷酸多样性的特点; 群体内的遗传距离0.0107~0.0184, 群体间的遗传距离0.0112~0.0172, AMOVA分析显示群体间的分子变异占0.66%, 群体内占99.34%; 中性检验结果表明Fu’s F_s检验值为显著的负值(-16.7079, p<0.01); 核苷酸不配对分布图呈单峰, 表明黄斑篮子鱼演化过程中经历过种群扩张事件, 推测扩张时间约在1.38~4.60万年前。综上, 华南沿海岸4个黄斑篮子鱼群体间不存在显著的遗传分化, 可划归一个管理单元, 而沙扒湾(SB)群体遗传多样性水平相对较高, 应优先加以保护。  相似文献   

Cost-efficient scheduling of FAST observations     

Qi Luo  Laiping Zhao  Ce Yu  Jian Xiao  Jizhou Sun  Ming Zhu  Yi Zhong 《Experimental Astronomy》2018,45(1):107-126

A cost-efficient schedule for the Five-hundred-meter Aperture Spherical radio Telescope (FAST) requires to maximize the number of observable proposals and the overall scientific priority, and minimize the overall slew-cost generated by telescope shifting, while taking into account the constraints including the astronomical objects visibility, user-defined observable times, avoiding Radio Frequency Interference (RFI). In this contribution, first we solve the problem of maximizing the number of observable proposals and scientific priority by modeling it as a Minimum Cost Maximum Flow (MCMF) problem. The optimal schedule can be found by any MCMF solution algorithm. Then, for minimizing the slew-cost of the generated schedule, we devise a maximally-matchable edges detection-based method to reduce the problem size, and propose a backtracking algorithm to find the perfect matching with minimum slew-cost. Experiments on a real dataset from NASA/IPAC Extragalactic Database (NED) show that, the proposed scheduler can increase the usage of available times with high scientific priority and reduce the slew-cost significantly in a very short time.  相似文献