结合水平集与光流的序列影像运动分割技术研究     

刘冰  余旭初  张鹏强  秦进春 《测绘科学技术学报》2016,(4)

提出一种结合变分水平集分割与变分光流的运动分割方法。该方法将光流能量函数与水平集分割能量函数进行整合形成新的运动分割能量函数,并采用变分方法进行优化。采用无人机序列影像对该运动分割方法进行实验分析,实验结果表明该方法在目标运动位移过大时,既能准确地估计出运动矢量,又能精确地分割出目标区域。  相似文献   

Experimental Study of Nonlinear Behaviors of A Free-Floating Body in Waves     

贺铭  任冰  邱大洪 《海洋工程》2016,(3):421-430

Nonlinear behaviors of a free-floating body in waves were experimentally investigated in the present study. The experiments were carried out for 6 different wave heights and 6 different wave periods to cover a relatively wide range of wave nonlinearities. A charge-coupled device (CCD) camera was used to capture the real-time motion of the floating body. The measurement data show that the sway, heave and roll motions of the floating body are all harmonic oscillations while the equilibrium position of the sway motion drifts in the wave direction. The drift speed is proportional to wave steepness when the size of the floating body is comparable to the wavelength, while it is proportional to the square of wave steepness when the floating body is relatively small. In addition, the drift motion leads to a slightly longer oscillation period of the floating body than the wave period of nonlinear wave and the discrepancy increases with the increment of wave steepness.  相似文献   

中国沿海管体星虫属(星虫动物门)的研究     

李凤鲁  周红  王玮 《中国海洋大学学报(自然科学版)》1992,(1)

报道作者采自我国沿海管体星虫属共计4种。其中富岛管体星虫Siphonosomafunafuti(Shipley)在我国是首次记载。  相似文献   

桶形基础平台海上沉放安装   总被引：3，自引：1，他引：3  

李蔚  时忠民等 《海洋工程》2001,19(1):19-23

桶形基础平台是世界上一种最新型的海洋平台，可广泛应用于海上油气田开发。为满足我国际油气田开发中卫星平台的结构和功能要求，桶形基础平台采用新的压载沉放方法安装，具有更高的效率和经济性。沉放过程中桶形基础平台受到水流和波浪的作用，结合模型试验对平台运动进行数值模拟分析，以了解在整个沉放过程中相应参数的变化趋势。根据桶形基础平台的特征，制定联台沉放方案，并通过压载实现平台的沉放控制。  相似文献   

海面动量、热量及水汽通量的浪沫效应──Ⅰ．方程组及初值化     

张淮  楼顺里 《中国海洋大学学报(自然科学版)》1995,(2)

讨论海面浪沫影响动量、热量及水汽等垂直通量的物理过程、提出描述飞沫特征的运动方程、热量方程和蒸发方程，以及确定飞沫初值的计算方法。并给出求飞沫在出入海面过程中所产生的动量、热量及水汽等通量的计算式。  相似文献   

Reproductive biology of the mackerel scad Decapterus macarellus from Cabo Verde and the implications for its fishery management     

MPV Costa  DRS Cruz  LS Monteiro  KSM Evora 《African Journal of Marine Science》2020,42(1):35-42

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.  相似文献   

平面二维流场中质点运动的可视化   总被引：2，自引：0，他引：2  

袁德奎  何磊  陶建华 《海洋通报》2004,23(5):77-81

对平面二维流场中质点运动的可视化进行了研究，提出了一种适用于三角形非结构化网格系统中质点运动轨迹的跟踪算法，利用数值计算方法的稳定性限制条件对质点位置的搜索算法进行了优化，极大地降低了算法的时间复杂度，提高了计算效率，采用Shepard插值法求解质点的速度，四阶龙格库塔方法积分质点的运动轨迹，选用Visual Fortran语言实现了质点运动的动态显示，将本文方法与平面二维潮流模型相结合，用于渤海潮流场中质点运动规律的研究，初步得出了渤海中质点运动和水效换的一些规律。  相似文献   

Numerical simulation of ship stability for dynamic environment     

S. Surendran  J. Venkata Ramana Reddy 《Ocean Engineering》2003,30(10):1305-1317

The prediction of ship stability during the early stages of design is very important from the point of vessel’s safety. Out of the six motions of a ship, the critical motion leading to capsize of a vessel is the rolling motion. In the present study, particular attention is paid to the performance of a ship in beam sea. The linear ship response in waves is evaluated using strip theory. Critical condition in the rolling motion of a ship is when it is subjected to synchronous beam waves. In this paper, a nonlinear approach has been tried to predict the roll response of a vessel. Various representations of damping and restoring terms found in the literature are investigated. A parametric investigation is undertaken to identify the effect of a number of key parameters like wave amplitude, wave frequency, metacentric height, etc.  相似文献   

西北太平洋热带气旋中期路径的统计释用综合预报模式   总被引：1，自引：0，他引：1  

钟元  李泓 《海洋预报》1996,13(2):17-28

提出一个热带气旋中期路径的统计释用综合预报模式。该模式应用ＴＣ参数，初妈时刻及未来时刻的环境场参数和导出因子，构造了多种中期天气时空惊讶的预报因子；应用数值天气预报产品的统计释用技术和多种分类预报模式的综合集成，构造了ＴＣ中期路径的客观定量预报模式。  相似文献   

海洋工程模型运动测量装置的研制     

金志华  田蔚风  施红兵 《海洋工程》1997,(1)

本文介绍由磁通门数字罗盘和改进的航空垂直陀螺仪构成的海洋工程模型运动测量装置。装置简单实用，性能稳定可靠，试用表明它能满足海洋工程模型在风浪流作用下有关运动的测量要求。  相似文献