基于AIS的海洋环境目标监测技术研究

介绍了由多种AIS监测平台获取船舶信息的方法,探讨基于AIS的海洋环境目标监测技术。介绍了AIS信息获取和融合技术,提出了同类传感器多源融合与异类传感器多源融合的模型,描述了船只目标信息提取与应用技术。通过收集处理AIS信息,可以大大扩展船舶的监视范围,对于提高船舶动态的监控能力和海上安全的保障能力具有很重要的意义。     

突发灾害监控与决策系统的设计与实现

现代社会,面对高危或人类无法到达的区域,如森林火场现场视查、地震灾情查看、城市等狭窄地段的高楼消防救灾、核辐射现场勘察检测等,基于无人机的无线通信系统,由于体积小和机动灵活,通过信息传感采集、视频现场捕捉,能安全、有效地获取现场灾情情况信息。然后数据通过中继传到后台,存入后台数据库。利用采集到的现场信息与ArcGIS Server发布的GIS相关服务,通过ArcGIS API for Flex对数据进行快速分析处理,使采集信息可视化,同时进行突发灾害模拟预测,准确定位事发地点,评价灾害影响范围,查找救援最短路径等。本文设计并实现了基于无人机突发灾害监控与决策系统,同时重点介绍系统的设计、组网的关键技术、视频压缩、基于GIS的数据处理与分析以及系统实现的功能。     

视频摘要研究综述

近年来,随着计算机技术的发展和终端设备的广泛使用,视频摘要技术得到了广泛的研究.视频摘要是数据摘要的重要研究方向.首先介绍了静态视频摘要的基本概念,然后对研究静态视频摘要的凸松驰方法和行列式点过程法的最新研究进展进行了概述.对于动态视频摘要,主要对分割视频和个性化视频摘要的最新研究进展进行了介绍.最后对视频摘要面临的问题以及将来的研究方向进行了介绍.     

面向高耸古塔的无人机视频环拍实景三维建模方法

针对高耸古塔的实景三维建模效率低、成本较高的问题,本文提出一种无人机三相位环拍视频匀分帧建模方法。选用配备单镜头相机的小型多旋翼无人机,布设高、中、低3个相位分别对高耸古塔进行环拍视频采集并进行匀分帧处理。选取宁夏银川市兴庆区承天寺塔为试验对象进行实例建模,并与广泛使用的无人机拍照摄影式倾斜摄影建模方法对比,从建模效率、建模空三质量及整体模型质量3方面对比两种采集方式的建模效果。结果表明,本文方法的建模效果优于无人机倾斜摄影的三维建模效果,在优化采集过程和简化设备条件的基础上,保证了模型的完整度,提升了建模效率和建模质量。     

Underwater video reveals decreased activity of rocky intertidal snails during high tides and cooler days

Nearly all of our understanding of rocky inter‐tidal ecology comes from studies conducted at low tide. To study inter‐tidal organisms at high tide, we anchored waterproof digital GoPro^® video cameras in wave‐exposed tidepools and recorded the daytime movements of the black turban snail, Tegula funebralis, over the tidal cycle between May and August 2012 near Bodega Bay, California. Overall, snails moved more quickly and presumably foraged more during low tides and on days with warmer air and perhaps water temperatures. This is similar to other ectotherms that exhibit increased metabolic rates, movement and foraging in warmer conditions. Snails also moved less during flood and high tides, may have moved downward in tidepools at flood tides, and showed evidence of reduced activity on days with larger waves. This inactivity and refuge seeking may have been a strategy to avoid dislodgment by waves. Analysis of snail trajectories showed foraging bouts indicated by alternating zig‐zagging and straight movement. There was no effect of temperature, wave height, or tidal phase on distribution of snail turning angles, suggesting that they may have foraged consistently but moved faster during warm conditions and low tides, thereby grazing a larger area. This is one of few direct recordings of inter‐tidal organisms on wave‐exposed rocky shores during high tide. The methods used here are easily transferable to other studies, which are needed to increase our understanding of behaviors that structure rocky shore communities during high tide.     

Time series video analysis of bubble release processes at natural hydrocarbon seeps in the Northern Gulf of Mexico

This research quantifies the rate and volume of oil and gas released from two natural seep sites in the Gulf of Mexico: lease blocks GC600 (1200 m depth) and MC118 (850 m depth). Our objectives were to determine variability in release rates and bubble size at five individual vents and to investigate the effects of tidal fluctuations on bubble release. Observations with autonomous video cameras captured the formation of individual bubbles as they were released through partially exposed deposits of gas hydrate. Image processing techniques determined bubble type (oily, gaseous, and mixed: oily and gaseous), size distribution, release rate, and temporal variations (observation intervals ranged from 3 h to 26 d). A semi-automatic bubble counting algorithm was developed to analyze bubble count and release rates from video data. This method is suitable for discrete vents with small bubble streams commonly seen at seeps and is adaptable to multiple in situ set-ups. Two vents at GC600 (Birthday Candles 1 and Birthday Candles 2) were analyzed. They released oily bubbles with an average diameter of 5.0 mm at a rate of 4.7 bubbles s⁻¹, and 1.3 bubbles s⁻¹, respectively. Approximately 1 km away, within the GC600 seep site, two more vents (Mega Plume 1 and Mega Plume 2) were analyzed. These vents released a mixture of oily and gaseous bubbles with an average diameter of 3.9 mm at a rate of 49 bubbles s⁻¹, and 81 bubbles s⁻¹, respectively. The fifth vent at MC118 (Rudyville) released gaseous bubbles with an average diameter of 3.0 mm at a rate of 127 bubbles s⁻¹. Pressure records at Mega Plume and Rudyville showed a diurnal tidal cycle (24.5 h). Rudyville was the only vent that demonstrated any positive correlation (ρ = 0.60) to the 24.5 h diurnal tidal cycle. However, these observations were not conclusive regarding tidal effects on bubble release.     

视频GIS数据采集系统的设计与实现

视频GIS数据采集系统是将地理信息与视频影像实时自动集成,生成空间位置与视频影像相融合的超视频信息。在视频GIS数据模型原理的基础上提出了在视频采集的同时,按照一定的时间或空间间隔,记录地理坐标、速度和相对应的视频帧数,通过建立视频时间或视频帧与其地理位置坐标、速度的对照表,来实现视频数据与空间地理数据的有机集成。并详细的阐述了该系统的设计和实现。     

Waveshapes of continuing currents and properties of M-components in natural positive cloud-to-ground lightning

This work analyses the waveshapes of continuing currents and parameters of M-components in positive cloud-to-ground (CG) flashes through high-speed GPS synchronized videos. The dataset is composed of only long continuing currents (with duration longer than 40 ms) and was selected from more than 800 flashes recorded in São José dos Campos (45.864°W, 23.215°S) and Uruguaiana (29.806°W, 57.005°S) in Southeast and South of Brazil, respectively, during 2003 to 2007 summers. The videos are compared with data obtained by the Brazilian Lightning Location System (BrasilDAT) in order to determine the polarity of each flash and select only positive cases. There are only two studies of waveshapes of continuing currents in the literature. One is based on direct current measurements of triggered lightning, in which four different types of waveshapes were observed; and the other is based on measurements of luminosity variations in high-speed videos of CG negative lightning, in which besides the four types above mentioned two additional types were observed. The present work is an extension of the latter, using the same method but now applied to obtain the waveshapes of positive CG lightning. As far as the authors know, this is the first report on M-components in positive continuing currents. We also have used the luminosity-versus-time graphs to observe their occurrence and measure some parameters (duration, elapsed time and time between two successive M-components), whose statistics are presented and compared in detail to the data for negative flashes. We have plotted a histogram of the M-components elapsed time over the total duration of the continuing current for positive flashes, which presented an exponential decay (correlation coefficient: 0.83), similar to what has been observed for negative flashes.     

Review of oil spill remote sensing

Remote-sensing for oil spills is reviewed. The use of visible techniques is ubiquitous, however it gives only the same results as visual monitoring. Oil has no particular spectral features that would allow for identification among the many possible background interferences. Cameras are only useful to provide documentation. In daytime oil absorbs light and remits this as thermal energy at temperatures 3–8 K above ambient, this is detectable by infrared (IR) cameras.     

基于热红外视频图像监测的海面溢油识别技术研究

针对现有海面溢油检测技术难以在石油泄漏初期（尚未形成海面大规模油膜覆盖）及时发现油膜的难题,本文在前期基于热红外图像测算海面油膜面积方法研究的基础上,结合油泄漏至海面后油膜的扩散特征,提出了一种基于热红外视频图像监测油膜面积变化以及时识别海面溢油的方法。首先,基于单帧热红外图像处理算法提取海面前景区域（包含油膜区域与相似物干扰区域）并计算各区域所代表的实际物理面积。基于视频图像处理技术跟踪测算前景区域中各连通区域的实际物理面积变化情况,根据各连通区域的面积变化率识别前景区域中是否存在油膜,从而判断海面是否发生溢油。实验结果表明：所提出的方法能有效识别不同黏度的石油泄漏至海面形成的扩散油膜,在水面包含波浪与相似物干扰时也具有良好的识别精度。该方法适用于特定场景下（如码头、船舶等）的溢油事故的鉴别,能为溢油事故的及时发现和预警提供技术支持。