共查询到20条相似文献，搜索用时 859 毫秒
1.
Replacing traditional light sources with light-emitting diode (LED) light modules is a global trend, especially for underwater illumination. The light intensity is dispersed evenly at all emission angles in traditional underwater light sources that use the radiative transfer model, resulting in the inclusion of scattering factors in the attenuation coefficient. The high directionality of LED light source modules causes the light intensity transfer in water to vary according to varying emission angles. This renders traditional underwater optical transfer theory irrelevant as an underwater LED light module design reference. Therefore, this study constructs an underwater LED light source transfer model using the light-field average cosine and the light transfer scattering probability method, and imports the LED luminous intensity distribution curve (LIDC) and axial luminous intensity. Experimental results showed that the illumination intensity of the underwater LED illumination module was less than 10% of the simulation. Therefore, this design method can be used to design the required illumination light modules for different underwater environments. Finally, the LED light module has been used for under water fish attractor lighting and enhanced the illumination zone efficiency (m3 per Watt) of 81% compared to the traditional high intensity discharge (HID) underwater fish attractor lamp. 相似文献
2.
针对水下目标图像探测一直是困扰海洋界的1个难题，进行了水下探测的线扫描系统的设计和相关试验。从实验结果来看，线扫描系统可以很好地描述水下物体的三维外形细节，对于水下目标探测、识别十分有效。 相似文献
3.
A simple underwater video system has been developed for simultaneously imaging sediment suspension and monitoring bed profiles under waves and combined wave-current flows. This consists of a diode-laser-generated light plane and a black-and-white underwater video camera. The laser light illuminates suspended material in section and also provides a bed profile at the bottom. Orthogonal laser/camera pairs are used to obtain both cross-shore and alongshore views. During deployments, the system has been augmented by acoustic backscatter devices for measurement of sediment concentration. As with all video techniques, visibility is a limiting factor, but where turbidity is low to moderate, the results are encouraging. Results on cross-shore and alongshore bed elevation variations and suspension event stales obtained with the video/laser system are presented for two experiments: one at the National Research Council Wave Research Flume in Ottawa, Canada, and the other in the field at Queensland Beach, N.S., Canada, 相似文献
4.
基于光学技术的水下气泡探测实验研究 总被引：1，自引：1，他引：0
热液/冷泉溢出含有硫化氢、甲烷、二氧化碳等化学成分的气泡。实验室模拟海底热液/冷泉资源溢出气泡环境搭建了实验平台,以甲烷气体为实验气体,在黑暗环境下用高速光电探测器对气泡后向散射光进行接收,用拉曼光谱仪实现甲烷气体气泡后向散射光的拉曼检测,并与计算拉曼光谱比较。由结果可知激光拉曼光谱可以探测到气泡后向散射光,并识别气泡中含有的气体成分。通过探测气泡成分,从而判定这些气泡是否来自海底热液/冷泉等甲烷资源溢出。这样的探测方式,探测准确率高,缓解探测深度,同时避免探测设备直接与海底资源直接接触而造成的寿命缩减,为将来的海洋探测与实际应用打下了良好的基础。 相似文献
5.
De Yao Azimi-Sadjadi M.R. Jamshidi A.A. Dobeck G.J. 《Oceanic Engineering, IEEE Journal of》2002,27(3):619-627
The problem of classifying underwater targets is addressed in this paper. The proposed classification system consists of several subsystems including preprocessing, subband decomposition using wavelet packets, linear predictive coding, feature selection and neural network classifier. A multi-aspect fusion system is introduced to further improve the classification accuracy. The classification performance of the overall system is demonstrated and benchmarked on two different acoustic backscattered data sets with 40- and 80-kHz bandwidth. A comprehensive study is then carried out to compare the classification performance using these data sets in terms of the receiver operating curves, error locations, and generalization and robustness on a large set of noisy data. Additionally, the importance of different frequency bands for the wideband 80-kHz data is also investigated. For the wideband data, a subband fusion mechanism is introduced which offers very promising results. 相似文献
6.
7.
8.
摄影测量的处理工作主要依赖于自动的影像匹配技术,如果影像之间的辐射差异越小,即摄影基线越短,则自动匹配精度越高,但是从理论上说基线越短空间交会精度越低,而水下由于众多干扰因素影响,空间交会的精度更低。针对这一难题,从理论上分析了空间交会精度的主要影响因子,考虑涉水拍摄环境时水对光线的折射影响,提出将超短基线多度重叠影像应用于涉水摄影测量,并通过双介质空间交会实验和水下空间交会实验,验证了在涉水情况下,利用超短基线多度重叠影像能够大幅度地提高水下目标物的空间交会精度。得出的结论对越来越多的涉水摄影测量应用具有积极的参考价值。 相似文献
9.
一种水下激光成像的新方法 总被引：1，自引：0，他引：1
在我国沿海近岸,急需通过激光同步扫描方法建立1套浑水观测系统,解决水下视觉问题。本文研究了激光在水下的传输特性,结合散射光的分布特性,确定同步扫描的光学结构设计,通过对获得的系统各类信号特性的分析,设计合适的成像系统;并从理论和水池试验两方面分别论证了这种系统消除散射影响的有效性;论述了这种系统在浑水中的宽视角场和全景深的优良特性。 相似文献
10.
《Oceanic Engineering, IEEE Journal of》2009,34(1):93-100
11.
《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(8):1455-1481
A submersible holographic camera has been developed for measuring the particle distributions, characteristics and motions within a sample volume in the ocean. Its main purpose is to provide data on the spatial distribution, size, shape, orientation, inter-particle relationships, turbulence, local shear and relative motion due to swimming and sinking of plankton. This battery powered, modular, self-contained system is remotely operated by a PC through fiber optic links. Data from on-board environmental sensors are used to select locations for recording holograms and relating the images to broader scale physical structures. The holocamera also has a buoyancy control system that allows deployment as a neutrally buoyant drifter or in a slow profiling mode. The instrument is currently configured for in-line holography, but it has been designed to be readily adaptable to off-axis holography. The cylindrical sample volume is 6.3 cm in diameter and its length can be varied from 10 to 68 cm. The light source is a pulsed ruby laser chosen predominantly because zooplankton are typically less sensitive to red light. The laser has independent dual flashlamps for maximum flexibility in selecting delay between exposures. About 300 single or multiple exposure holograms can be recorded during a single deployment. Data such as particle size, shape, orientation, distribution in space and velocity are obtained by reconstructing the holograms, scanning them with a video camera equipped with a microscope objective, digitizing the images and analyzing relevant data. Several recent field tests have demonstrated the system reliability and resolution. Particles with sizes as small as 10 μm and details on cell structures of larger particles in the 3–5 μm range could be identified and used for identifying and categorizing the particles. Sample single and double exposure images, the latter for measuring motion, and sample spatial distributions are provided. Methods for mapping the liquid velocity distribution are addressed briefly. Parameters affecting the image resolution and location in space, such as particle density, distance from the film plane and focus are discussed and demonstrated. 相似文献
12.
基于声学仪器与粒径分析仪研究东海浮游动物昼夜垂直迁移过程 总被引：1，自引：0，他引：1
浮游动物的昼夜迁移活动与其种群变动和摄食节律紧密联系,浮游动物昼夜移动的研究已经成为种群动力学研究的一个重要组成部分。2013年夏季在浙江东部近海,结合声学多普勒流速剖面仪(ADCP)和激光粒径分析仪(LISST-100)等仪器进行了一次定点周日连续观测。通过声学反演方法,得到后向散射强度剖面的时间变化,结合LISST-100得到的水体悬浮物粒径谱,研究了浮游动物垂直迁移及其习性。分析发现了可能是精致真刺水蚤的一次昼夜垂直迁移过程,其在夜间进入跃层附近进食,白天蛰伏于底层低温高盐的台湾暖流水中,垂向迁移速度达到了0.05 m/s。LISST-100观测还发现在夜间跃层边界处大粒径颗粒聚集和100～150 μm大小的颗粒物的减少,水体中不同粒径的悬浮颗粒物有明显的昼夜变化节律,推测水体中不同层次生物群落结构存在昼夜差异。 相似文献
13.
This paper describes a new framework for object detection and tracking of AUV including underwater acoustic data interpolation, underwater acoustic images segmentation and underwater objects tracking. This framework is applied to the design of vision-based method for AUV based on the forward looking sonar sensor. First, the real-time data flow (underwater acoustic images) is pre-processed to form the whole underwater acoustic image, and the relevant position information of objects is extracted and determined. An improved method of double threshold segmentation is proposed to resolve the problem that the threshold cannot be adjusted adaptively in the traditional method. Second, a representation of region information is created in light of the Gaussian particle filter. The weighted integration strategy combining the area and invariant moment is proposed to perfect the weight of particles and to enhance the tracking robustness. Results obtained on the real acoustic vision platform of AUV during sea trials are displayed and discussed. They show that the proposed method can detect and track the moving objects underwater online, and it is effective and robust. 相似文献
14.
Robert W. Owen Jr. 《Journal of Oceanography》1973,29(5):171-184
Relationships of light scattering to particle concentration and size distribution were experimentally determined to follow theoretical findings, both in laboratory suspensions and in a variety of conditions in the natural marine environment. Confirmation was obtained by electronic particle counts paired with scattering measurements that light scattering provides a measure of concentration of particle cross-section in the sea. The use of light scattering as a measure of particle bulk concentration is shown to require constancy of the distribution of particle size, which is met under prescribed circumstances in the upper part of the sea. A simple test can indicate the constancy of the size distribution. A tentative estimate is made of the effect particles have on the inherent properties of open ocean water. 相似文献
15.
The purpose of the current study is to introduce a set of mobile underwater positioning systems (MUPS) that will enable non-offshore vessels to execute underwater missions. Besides mobility, the system would also possess the advantage of having to use fewer acoustic instruments than conventional acoustic positioning systems. The method adopted by the system will involve the use of expendable and multi-functional bathythermographs (XBT) to measure the underwater acoustic speed and the depth of water at the same time. Then it must utilize the geometric relations formed by measuring the position of underwater targets at set intervals during navigation. In addition, since sound does not travel in a straight line when underwater, the iteration and convergence method must be used to perform corrections on the transmission speed and positional errors to obtain an accurate coordinate of the underwater target. After simulation testing, the positioning system established by the current study has proven to be fast in converging the error values along with high positioning accuracy of the system. The results of the study indicate that the MUPS built by the research institute can be utilized on a vessel, and will be very helpful in assisting the management of urgent underwater positioning missions. 相似文献
16.
随着对水下目标特性研究的深入和声学探测技术的发展,基于单模态的阵列式信息融合或基于空间信息的分布式信息融合的水下目标识别方法研究已有一定成果,但针对复杂海况导致单一物理场或单一融合层次的系统识别性能提高有限等方面影响的水下目标识别方法研究还有所不足,因此,开展基于多模态深度融合模型的水下目标识别方法研究可利用模态互补,共享信息而提升识别率。文中在国内外研究基础上,深入研究了基于到达时差法和多模态方法组合的检测方法,初步形成了基于水声环境空间中多模态深度融合模型的识别框架,开展了海洋中典型自然与人为事件的信号分析与特征提取,并在此基础上,设计新型基于海底基站的被动识别系统。该系统同步记录和由位置等组成的时间序列标记声、磁和压数据,可实现高精度、高分辨率的识别。本研究可满足未来海洋观测对高性能水下目标探测、定位和跟踪系统的迫切需要,为海洋安全监管、海洋突发事件应急响应等领域提供新的技术手段和科学参考。 相似文献
17.
18.
针对海洋环境下自主水下机器人（AUV）的路径规划问题,提出了一种基于框架四叉树的改进量子粒子群算法（QPSO）,首先使用框架四叉树的方法对障碍物建模,该方法提高了建模的精度且对后续算法的效率也有极大的改进,之后设计改进的量子粒子群算法,并且结合水下环境的特殊性设计适应度函数,综合考虑航线路径长度、偏转角度以及海流影响,使得算法可以在水下环境中寻得能耗最短的解路径。最后通过仿真试验验证,相比于传统的栅格法和粒子群算法,改进量子粒子群算法的运算时间更短,收敛速度更快,其独特的适应度函数可以使AUV能更好适应水下多变的环境,且能利用海流设计能耗更小的路径,具有很大的实用价值。 相似文献
19.
激光扫描实时获取水下图象信息的方法与系统 总被引：1，自引：1，他引：0
报道一种实时大视角、全景深获取水下图象的新方法。该方法试图解决在无人摇控潜器(ROV)和自治式潜器 (UUV)走航式获取水下清晰图象时 ,遇到的激光在水下传输过程中后向散射噪声问题 ,建立了一种具有宽视角、全景深性能的水下激光扫描系统。用这种方法和系统在空气中和水中做了大量的实验 ,并讨论了这种方法和系统的应用前景。 相似文献
20.
针对水下机器人作业过程中的近距离引导水下对接问题,以自治缆控水下机器人(ARV)为研究对象,为实现快速、高精度的水下对接,设计了基于反射光源识别的单目视觉辅助水下对接方法。通过在对接口布置反光带并将其作为目标图像,设计了图像处理和特征点提取的算法,经过图像特征信息的分析处理,优化算法的时间复杂度,提高了特征点提取的准确率和识别效率。最后设计了传统的引导灯方案与反光带方案的对比试验,验证算法的可行性,证明在水下环境下识别反射光源的方法极大提升了位置估计的准确率,同时在计算速度上也有显著提高,弥补了传统水下对接方法中精度不足或计算量大的缺陷,更好地满足了ARV水下对接的需求,能为潜水器实现水下自主对接提供参考依据。 相似文献