基于应急地理信息的云服务系统关键技术研究

随着测绘地理信息服务应用各行业方面作用愈趋明显,为有效应对我国各种自然灾害频发的严峻情况,减少灾害带来的损失,建立和完善应急地理信息保障服务体系显得非常重要,同时应急保障体系研究也一直是应急领域前沿的问题。本文采用云服务技术构建基于时空信息云平台的应急地理信息服务系统关键技术进行研究,实现应急演示、数据交换、应急时空数据库管理、应急信息发布、应急保障服务等,从而将各类多源应急信息资源深度整合管理、地图浏览展示,提高应急地理信息共享和综合利用水平。     

两种海浪模式对中国黄海海域浪高模拟能力的比较

本文利用第三代海浪数值模式WAVEWATCH和SWAN模式,分别对黄海区域进行了理想模拟计算和实际浪场的模拟计算,结果表明:理想状态下两种模式的模拟结果在大小和空间分布上都不相同,但在大小及其变化趋势士相差不大;在实际模拟中,将两种模式的模拟结果与实际观测值相比,发现SWAN模式模拟结果较WAVEWATCH模式好,只是在高风速的模拟情况下,SWAN模式模拟结果偏大,而WAVEWATCH模式模拟结果偏小.     

风浪对海-气界面动量通量估计的影响

利用实验室和有代表性的外海观测数据综合分析表明,海面粗糙度对波龄的依赖性与是否将实验室和外海数据一起考虑有关,而风应力拖曳系数与此无关,且随波龄增大而减小.利用Toba-3/2指数律和风浪成长关系的分析表明,风应力拖曳系数为常数或随波龄的增大而增大,与上述结果定性上相矛盾,说明风浪对风应力拖曳系数影响问题需要进一步研究.     

基于PointNet的点云数据处理及识别技术应用研究

主要基于PointNet模型对点云数据进行特征分类处理,直接对无序化的三维点云数据进行无规则输入处理,通过对无序化的点云数据中的每一个点进行单独的处理,来实现点云数据的输入,与点的输入顺序没有关系,在PointNet中最重要的方法是对称函数最大池化来合并点云数据中每一个点的信息,输出分类特征集合或分割结果,然后结合计算机视觉的神经网络和深度学习等方法,来理解和分析点云数据对物体和环境的智能化识别的应用研究.     

利用本质矩阵进行低空无人机影像位姿恢复的研究

随着无人机的广泛应用,其相机安置方式及摄影姿态的任意化,造成影像基线方向多样化,利用传统的航空摄影测量方法处理此类影像较为困难。本文提出了一种基于本质矩阵恢复此类无人机影像位姿的方法。经试验证明,本文提出的定向测量不仅可以快速确定基线方向,求解影像外方位元素,而且重投影误差在1个像素以内。     

An investigation of the effects of wave state and sea spray on an idealized typhoon using an air-sea coupled modeling system

In this study, the impact of atmosphere-wave coupling on typhoon intensity was investigated using numerical simulations of an idealized typhoon in a coupled atmosphere-wave-ocean modeling system. The coupling between atmosphere and sea surface waves considered the effects of wave state and sea sprays on air-sea momentum flux, the atmospheric low-level dissipative heating, and the wave-state-affected sea- spray heat flux. Several experiments were conducted to examine the impacts of wave state, sea sprays, and dissipative heating on an idealized typhoon system. Results show that considering the wave state and sea-spray-affected sea-surface roughness reduces typhoon intensity, while including dissipative heating intensifies the typhoon system. Taking into account sea spray heat flux also strengthens the typhoon system with increasing maximum wind speed and significant wave height. The overall impact of atmosphere-wave coupling makes a positive contribution to the intensification of the idealized typhoon system. The minimum central pressure simulated by the coupled atmosphere-wave experiment was 16.4 hPa deeper than that of the control run, and the maximum wind speed and significant wave height increased by 31% and 4%, respectively. Meanwhile, within the area beneath the typhoon center, the average total upward air-sea heat flux increased by 22%, and the averaged latent heat flux increased more significantly by 31% compared to the uncoupled run.     

New Interpretation of Dependence of Wind Stress on Wave State

Based on observations from buoys, it is found that the wave age is well correlated with the nondimensional wave height, and this correlation is best described by a 3/5-power law. This similarity law is valid in the cases of wind waves as well as swells under natural sea states. On the basis of the 3/5-power law combined with the well-known 3/2-power law, it is shown that the wave-induced wind stress increases rapidly with wave age, indicating that the traditional observations or analytic techniques have only given the turbulent Reynolds stress induced by short wind waves, but excluded the long-wave-induced wind stress. The latter constitutes a small fraction to the total wind stress when the wave age is smaller than 1.0. The increase of sea-surface roughness with wave age can be attributed to wave breaking.     

块体空气动力算法的再计算湍通量与NCEP湍通量的比较

以NCEP资料提供的水文气象参数作为输入量,利用4种块体空气动力算法重新计算了动量和热量通量,与相应的NCEP自身提供的湍通量进行了比较分析,发现再计算动量、感热和潜热通量的偏差值随风速增加而增大;在中高风速下,再计算动量通量的相对误差较小,其他情况下再计算动量、感热和潜热通量的相对误差最高能达到50%左右;相对误差一般随纬度的增大而增大,表明两者之间存在不协调性。研究还表明,改进后的NCEP2资料与NCEP1资料相比,这种不协调性并没有得到改善。     

海-气界面动量通量的估计方法分析与应用

首次将经验模态分解方法引入湍流稳定性分析,与传统的线性和滑动平均去势方法进行了比较,发现经验模态分解方法的去势效果最好。基于"南海平台通量观测计划"(FOPSCS)近两年的连续通量观测数据,得到了22 476个摩擦速度的估算值,结果表明,当风速小于5m/s时,拖曳系数随风速增大而减小,而风速大于5m/s时,拖曳系数随风速增大而增大,两种情形分别反映了黏性表皮摩擦和波浪引起的形状阻力对海面风应力的贡献。同时发现短风区情形的拖曳系数大于长风区情形,说明波浪成长状态会对海-气界面动量交换产生影响。     

风浪和涌浪分离方法的比较（英文）

海浪通常以风浪和涌浪混合的形式存在,如何进行分离风浪和涌浪一直是海浪理论研究和海洋工程应用中的重要问题。本文利用模型试验和实测资料,对目前提出的一种二维谱风涌浪分离方法（2D法）和三种一维谱风涌浪分离方法（PM法、WH法、JP法）进行了检验,分析发现：2D法给出的结果整体而言最为可靠,与2D法相比,PM法明显高估了风浪成分,WH法低风速时高估了风浪,高风速时跟2D法比较接近,而JP法在整体上高估了风浪成分。通过调整分割频率的比例系数,改进了PM法,改进后的PM法给出的分离结果与2D法最为一致。