波罗的海芬兰湾第四纪沉积     

C.  HH 赵奎寰 《海岸工程》1997,16(3):75-80

通过对芬兰湾第四纪沉积断面声学探测和地质钻探结果发现与波罗的海盆地各发育阶段相适应的4种结构杂岩体。结构杂岩体的形成受结构和冰川动力作用控制，还受海底地形制约。水动力作用对与海相有关的新杂岩体的形成起着决定性作用，因为这些作用增强了海底侵蚀作用，并形成了复杂的堆积一侵蚀组合形态，即现时所称的海底流地质痕迹。本文以科学考察船“瓦维洛夫院士·谢尔盖”号第9航次于芬兰湾东部进行声学探测和地质钻探获得资料为基础（1991年，见图1），声学探测使用的是多道回声探测仪，波段为2．5～5．okHZ。在软底质，探测深度达几…  相似文献   

Parallel Neural Network-Based Motion Controller for Autonomous Underwater Vehicles   总被引：2，自引：0，他引：2  

甘永 王丽荣万磊  徐玉如 《中国海洋工程》2005,19(3):485-496

A parallel neural network-based controller （PNNC） is presented for the motion control of underwater vehicles in this paper. It consists of a real-time part, a self-learning part and a desired-state programmer, and it is different from normal adaptive neural network controller in structure. Owing to the introduction of the self-learning part, on-line learning can be performed without sample data in several sample periods, resulting in high learning speed of the controller and good control performance. The desired-state programmer is utilized to obtain better learning samples of the neural network to keep the stability of the controller. The developed controller is applied to the 4-degree of freedom control of the AUV “IUV- IV” and is successful on the simulation platform. The control performance is also compared with that of neural network controller with different structures such as normal adaptive neural network and different learning methods. Current effects and surge velocity control are also included to demonstrate the controller＇ s performance. It is shown that the PNNC has a great possibility to solve the problems in the control system design of underwater vehicles.  相似文献   

Morphological Evolution and Its Response to the Navigational Improvements in the North Passage,Yangtze Estuary     

刘杰  陈吉余  徐志扬  乐嘉海 《中国海洋工程》2007,21(4):611-624

By use of bathymetric chart,recent change of the riverbed in the North Passage of the Yangtze Estuary has been studied in this paper.The main channel of the upper,middle and lower(section)in the North Passage has been successively eroded and its groin field significantly deposited.At the same time,sediment has been deposited on the entrance region.Erosion and deposition had responded rapidly to the construction of the regulation engineering.There was about one year duration of lagging between erosion in the deep channel and the construction of the regulation engineering.The siltation lag of time in the groin field varied with the initial depth,but the average deposited thickness was about 0.5 m per year.Volumetric analysis demonstrates that there is a increasing trend of siltation in the North Passage after 2002,because of the difference in duration and quantity between erosion in the deep channel and deposition in the groin field.The water volume of the North Passage was reduced by ≈9%(280 million m3)between 2002 and 2006.Sediment budget reveals that the main sediment deposited in the North Passage takes its source from the river and the ocean.The decreasing water volume was attributable to shoaling in the groin field.Its triggering factors for increased sedimentation are the navigational improvements(jetties and groins)after 1998,which altered the passage boundary and destroyed the equilibrium state on the average ebb and flood sediment fluxes.The establishment of a stable estuary is attributed to a reduction in depth of the groin field.The forecast on the sediment deposition quantity and continuous infilling time in the groin system is about 325×106m3 and 6～7 years,respectively.  相似文献   

A Study on Crack Detection with Modal Parameters of A Jacket Platform   总被引：1，自引：0，他引：1  

张兆德  王德禹 《中国海洋工程》2004,18(1):1-10

Crack detection procedures by different modal parameters are analyzed for identitying a crack and its location and magnitude in a jacket plafform. The first ten natural frequencies and modal shapes of the jacket models are obtained by numerical experiments based on NASTRAN Code. A crack at different locations and of different magnitudes is imposed in the model at the underwater beams. Then, the modal evaluation parameters are calculated numerically, to illustrate the evaluation of modal parameter criteria used in jacket crack detection. The sensitivities of different modal parameters to different cracks are analyzed. A new technique is presented for predicting the approximate location of a breakage in the absence of the data of an intact model. This method can be used to detect a crack in underwater menbers by use of incomplete mode shapes of the top members of the jacket.  相似文献   

Datasonics声学背散射系统的改进技术     

周明 《海洋技术学报》1990,(1):59-66

本文阐述了我国首次引进的一套水体声学探测系统在应用中存在的问题,并给出了具体改进的方法。改进后的系统已用于一九八九年六月在大连进行的倾废实验,并得到了满意的结果。  相似文献   

利用测井探测天然气水合物并通过电阻率测井估算布莱克海岭的水合物浓度（饱和度）及天然气体积     

《海洋地质》2005,(2):13-32

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基于不同声波频率的底泥探测技术研究          下载免费PDF全文

张杰  张坤军  陈佳兵  李京兵 《海洋技术学报》2020,39(2):53-57

声学技术是水下勘探的主要技术手段,研究典型工况下主要声学设备声波频率与其底泥穿透能力的关系,将为改进底泥分层探测方案和声学设备的选取提供技术依据。本文在典型水域(滨海、河道、水库)应用不同声波频率进行定点底泥穿透深度试验,并在同一点利用定深采样钻采集底泥柱状样,以5～10 cm间隔分层并检测每层含水率,以含水率为指标对底泥进行分类,最后,对底泥柱状样本和声波底泥穿透深度结果进行对比分析。结果表明,12～33 k Hz频段声波可穿透河床到达浮泥、流泥层。在滨海水域中,低频声波可穿透部分淤泥层,且频率越低,穿透深度越大。12 k Hz频率的双频换能器相比24 k Hz和33 k Hz具有更强的穿透能力,可满足对浮泥、流泥及部分淤泥层的探测。  相似文献   

实验室模拟海水结冰装置与试验     

郭纪捷  郑国芝 《海洋技术学报》2003,22(4):7-11

研究海冰的声学探测技术需要实际海冰和低温环境。介绍了设计制造模拟海水结冰的试验装置的方法。采用人工制冷技术在实验室环境下实现了封闭容器里海水表面冻结一定厚度的海冰。试验结果表明，将容器中接近冰点的海水持续冻结32h后，海冰的厚度达到20cm。对容器里的海冰进行了声波信号探测冰水界面的试验，为测冰声呐技术研究和测冰试验创造了有利条件。  相似文献   

海底表层底质探测系统测试仪的设计     

吴炳昭  许枫 《海洋测绘》2007,27(2):53-55

海底表层底质探测系统是一种新型的声学探测设备,它利用声学信号实时走航式地遥测海底的表层底质。本测试仪用于在试验室条件下对海底表层探测系统性能的测试。由于该测试仪在设计过程中充分考虑到了目前测深仪的情况,所以也可以用于测深仪的性能测试。  相似文献   

多模光导纤维光学声探测     

郑国星  冯天瑾 《山东海洋学院学报》1985,15(2):9-13

The phase modulation of a laser beam in single mode fiber by pre sure-induced refractive index variations produced by an acoustic wave propagating in a fluid has been studied in detail by many workers. This paper describes the phase modulation principle of a laser beam in multimode fiber by presure-induced refractive index variations produ ted by an acoustical wave,and it’s experimental results. The construction of producing the fixed phase difference and the modulation index in a multimode fiber is different from in a single mode fiber.But both results of sound detection are the same.  相似文献