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   

Time-based signal characteristics as predictors of fish size and species for a side-looking hydroacoustic application in a river   总被引：1，自引：1，他引：1  

Burwen  Debby L; Fleischman  Steven J; Miller  James D; Jensen  Mark E 《ICES Journal of Marine Science》2003,60(3):662-668

  相似文献   

3D visualization for pelagic fisheries research and assessment     

Mayer  Larry; Li  Yanchao; Melvin  Gary 《ICES Journal of Marine Science》2002,59(1):216-225

  相似文献   

Deblurring of GLORIA side-scan sonar images     

D. C. Mason  T. P. LeBas  I. Sewell  C. Angelikaki 《Marine Geophysical Researches》1992,14(2):125-136

In side-scan sonars such as GLORIA, along-track resolution is usually much worse than across-track resolution. This paper shows how along-track resolution may be improved by the application of an image restoration (deblurring) technique known as the Jansson-van Cittert method. Employing a model of the image formation process, this involves iterated convolution of the estimated deblurred image radiances with the theoretical alongtrack point spread function. The method and its implementation for GLORIA images are described. Smoothing of high frequency noise prior to restoration has been found to lead to an improved end-product. The restored images exhibit sharper edges and a greater clarity much appreciated by the interpreter. This visual impression is borne out by quantitative measurement. The technique is shown to be a useful adjunct to the battery of digital preprocessing techniques which can be applied to the sonar image prior to the information extraction stage.  相似文献   

Contribution of the multibeam acoustic imagery to the exploration of the sea-bottom   总被引：1，自引：0，他引：1  

J. M. Augustin  R. Le Suave  X. Lurton  M. Voisset  S. Dugelay  C. Satra 《Marine Geophysical Researches》1996,18(2-4):459-486

  相似文献   

现代长江口水下底坡上的微地貌类型及分区     

陈卫民  杨作升  曹立华  郭志刚  刘浩  杜静萍 《中国海洋大学学报(自然科学版)》1993,(Z1)

旁侧扫描声纳记录真实地揭示出现代长江口水下底坡上发育的微地貌形态。指出微地貌的形态特征及其分布规律与长江泥沙的传输分布、长江口区海域的水动力机制密切相关。  相似文献   

Recording the migration behaviour of fish schools by multi-beam sonar during conventional acoustic surveys     

Hafsteinsson  M. T.; Misund  O. A. 《ICES Journal of Marine Science》1995,52(6):915-924

  相似文献   

Geometric corrections on sidescan sonar images based on bathymetry. Application with SeaMARC II and Sea Beam data     

Pierre Cervenka  Christian De Moustier  Peter F. Lonsdale 《Marine Geophysical Researches》1994,16(5):365-383

Acoustic backscatter images of the seafloor obtained with sidescan sonar systems are displayed most often using a flat bottom assumption. Whenever this assumption is not valid, pixels are mapped incorrectly in the image frame, yielding distorted representations of the seafloor. Here, such distortions are corrected by using an appropriate representation of the relief, as measured by the sonar that collected the acoustic backscatter information. In addition, all spatial filtering operations required in the pixel relocation process take the sonar geometry into account. Examples of the process are provided by data collected in the Northeastern Pacific over Fieberling Guyot with the SeaMARC II bathymetric sidescan sonar system and the Sea Beam multibeam echo-sounder. The nearly complete (90%) Sea Beam bathymetry coverage of the Guyot serves as a reference to quantify the distortions found in the backscatter images and to evaluate the accuracy of the corrections performed with SeaMARC II bathymetry. As a byproduct, the processed SeaMARC II bathymetry and the Sea Beam bathymetry adapted to the SeaMARC II sonar geometry exhibit a 35m mean-square difference over the entire area surveyed.On leave at the Naval Research Laboratory, Code 7420, Washington D.C. 20375-5350.  相似文献   

Processing Multibeam Backscatter Data   总被引：1，自引：0，他引：1  

Qiu-hua Tang  Xing-hua Zhou  Zhong-chen Liu  De-wen DU 《Marine Geodesy》2005,28(3):251-258

A new highly precise source of data has recently become available using multibeam sonar systems in hydrography. Multibeam sonar systems can provide hydrographic quality depth data as well as high-resolution seafloor sonar images. We utilize the seafloor backscatter strength data of each beam from multibeam sonar and the automatic classification technology so that we can get the seafloor type identification maps. In this article, analyzing all kinds of error effects in backscatter strength, data are based on the relationship between backscatter strength and seafloor types. We emphasize particularly analyzing the influences of local bottom slope and near nadir reflection in backscatter strength data. We also give the correction algorithms and results of these two influent factors. After processing the raw backscatter strength data and correcting error effects, we can get processed backscatter strength data which reflect the features of seafloor types only. Applying the processed backscatter strength data and mosaicked seafloor sonar images, we engage in seafloor classification and geomorphy interpretation in future research.  相似文献   

Progressive deformation of an evaporite-bearing accretionary complex: SeaMARC I,SeaBeam and piston-core observations from the Mediterranean Ridge     

Kim A. Kastens  Nancy A. Breen  Maria B. Cita 《Marine Geophysical Researches》1992,14(4):249-298

The Mediterranean Ridge is an arcuate ridge of deformed sediment caught up in the convergent plate margin between the African plate and the Aegean. An intensive campaign of SeaMARC I and SeaBeam surveys followed by piston coring has been conducted along the contact between undeformed turbidites of the Sirte Abyssal Plain and folded and faulted sediments of the Mediterranean Ridge. Along the outer edge of the Ridge, surficial sediments have been deformed into sinusoidal ridges and troughs (wavelengths 0.5–2 km, amplitude 20–150 m), which we interpret as folds. In plan view, the ridge and the trough fabric parallels the NW-SE trending regional contours, suggesting that the folds formed in response to compression orthogonal to the Mediterranean Ridge. The outermost ridge is shedding a debris apron out onto the abyssal plain, implying that uplift and deformation are ongoing. We show that the geometry of the outermost folds can be produced by elastic bending of a packet of 5–10 relatively strong layers, each 10–20 m thick, interbedded between weaker layers; we equate the strong layers with gypsum beds in the Messinian upper evaporites. Folding the seafloor from a flat layer into the observed ridge and trough topography would shorten the layer by less than 2%. Two percent shortening (equals two percent thickening) is insufficient to create the observed relief of the Mediterranean Ridge even if the entire sediment column down to basement were involved; we infer that additional shortening/thickening is accommodated by thrust faulting above a decollement at the top of the Messinian salt layer. At distances > 15 km from the deformation front and more than 500 m from the abyssal plain, sharp-edged, fine-grained side-scan lineations with very little vertical relief cut across the kilometer-scale ridge and trough topography. These fine-grained lineations fall in two groups trending N/S to NNE/SSW and ~ENE. We interpret these lineaments as traces of conjugate strike-slip faults formed in the same compressional regime which formed the NW/SE trending folds. The onset of strike-slip faulting may coincide with the cessation of imbricate thrust fan development above the initial salt-controlled decollement surface. The following characteristics of the Mediterranean Ridge are attributed to the presence of evaporites in the incoming sedimentary section: (1) initial deformation by folding rather than thrust faulting; (2) narrow taper; (3) rapid rate of outward growth; (4) karstification.  相似文献