共查询到14条相似文献，搜索用时 31 毫秒
1.
Seabed Classification Using BP Neural Network Based on GA 总被引：4，自引：0，他引：4
INTRODUCTIONUnderwaterremotesensingtools,suchasmulti beam ,sidescansonar,sub bottom pro file ,video ,etc .,arenormalmeanstoexploreseabed .Foreaseofnotation ,sidescansonarim ageisusedtodemonstrateseabedimage .Sidescansonarisakindofhigh resolutionimagingandcancontinuouslymonitorthechangesofseafloor.Inordertorelievetechniciansfromhardhandwork ,theautomaticclassificationbycomputerisneeded .Differentfromthespatialremotesensingimage ,underwatersonarimageistheformernon multi spectralimage .Theo… 相似文献
2.
Scour of the Seabed Under A Pipeline in Oscillating Flow 总被引：3，自引：0，他引：3
The scour of the seabed under a pipeline is studied experimentally in this paper. Tests are carried out in a U-shaped oscillatory water tunnel with a box imbedded in the bottom of the test section. By use of the standard sand, clay and plastic grain as the seabed material, the influence of the bed material on the scour is studied. The relationship between the critical initial gap-to-diameter ratio above which no scour occurs and the parameters of the oscillating flow is obtained. The self-burial phenomenon, which occurs for the pipeline not fixed to two sidewalls of the test section, is not observed for the fixed pipeline. The effect of the pipe on sand wave formation is discussed. The maximum equilibrium scour depths for different initial gap-to-diameter ratios, different Kc numbers and different bed sands are also given in this paper. 相似文献
3.
1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo… 相似文献
4.
A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. Seabed dynamic stresses from experiments are, tound to differ from theoretical resuhs. The response of p0 in permeable seabed has a small decay and phase shift to the nonlinear wave actions, and the dynamic stresses, σs/p0, σh/p0 and u/p0, contain different phase shift characteristics. Such phenomena will strongly affect the dynamic stress path in seabed. If the phase shifts of σs. and σh are neglected, the stress path will become a straight line; otherwise, it will become an elliptical curve. In phase shift cases, the long axis of the p - q diagram will be shortened when the depth increases, and the short axis will become longer when the phase shift increases. For the p＇ - q＇ diagram, the larger the phase lag of u, the longer the short axis. Relative results offer useful information for the analysis of seabed stability. 相似文献
5.
A plane strain analysis based on the generalized Biot's equation is utilized to investigate the wave-induced response of a poro-elastic seabed with variable shear modulus.By employing integral transform and Frobenius methods,the transient and steady solutions for the wave-induced pore water pressure,effective stresses and displacements are analytically derived in detail.Verification is available through the reduction to the simple case of homogeneous seabed.The numerical results indicate that the inclusion of variable shear modulus significantly affects the wave-induced seabed response. 相似文献
6.
1 .ＩｎｔｒｏｄｕｃｔｉｏｎＳｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓｍａｙｂｅｔｈｅｍａｉｎｄｅｓｔｒｕｃｔｉｖｅｌｏａｄｓｆｏｒｏｆｆｓｈｏｒｅｅｎｇｉｎｅｅｒｉｎｇｅｓｔａｂｌｉｓｈｍｅｎｔ.Ｔｈｅｓｅａｂｅｄｏｉｌ ｇａｓｐｉｐｅｌｉｎｅｎｅｔｗｏｒｋｉｓｔｈｅｌｉｆｅｌｉｎｅｆｏｒｏｆｆｓｈｏｒｅｏｉｌｆｉｅｌｄｐｒｏｄｕｃｔｉｏｎａｎｄｓｕｐｐｌｙ .Ｔｈｅｆａｉｌｕｒｅｏｆａｐｉｐｅｌｉｎｅｗｉｌｌｈａｖｅａｄｉｒｅｃｔｅｆｆｅｃｔｏｎｏｉｌｆｉｅｌｄｐｒｏｄｕｃｔｉｏｎ .Ｔｈｅｃｏｎｓｅｑｕ… 相似文献
7.
Based on Biot＇s consolidation theory, a two-dimensional model for computation of the seabed response to waves is presented with the finite element method. Numerical results for different wave conditions are obtained, and the effects of wave non-lineafity on the wave-induced seabed response are examined. Moreover, the wave-induced momentary liquefaction in uniform and inhomogeneous seabeds is investigated. It is shown that the wave non-linearity affects the distribution of the wave-induced pore pressure and effective stresses, while the influence of wave non-linearity on the seabed liquefaction potential is not so significant. 相似文献
8.
XU Changjie CAI Yuanqiang 《中国海洋工程》2001,(4):579-588
Based on the former research, the mechanism of the influence of the medium structure on the sound velocity of the three- phase seabed deposit is discussed by theoretical method. Through analysis of several structure models of three- phase seabed deposit, an equation of sound velocity is presented, which can describe the effect of structure of three-phase deposit on its acoustic velocity. Seen form the derived equation, the equations of the sound velocity of the deposits with different medium structures are different, the influence of the medium structure on the sound velocity is apparent. The equation in the paper provides the theoretical basis to understand the mechanics properties through sound velocity test, and it can be easily adopted in engineering. The influences of the parameters of deposits, void ratio, gas concentration and modulus on sound velocity through the deposit are investigated by numerical analysis of the acoustic velocity. Numerical result shows that the sound velocity of three-phase 相似文献
9.
In the paper,a weak coupling numerical model is developed for the study of the nonlinear dynamic interaction between water waves and permeable sandy seabed.The wave field solver is based on the VOF(Volume of Fluid)method for continuity equation and the two-dimensional Reynolds Averaged Navier Stokes(RANS)equations with a k-ε closure.The free surface of cnoidal wave is traced through the PLIC-VOF(Piecewise Linear Interface Construction).Biot's equations have been applied to solve the sandy seabed,and the u-p finite element formulations are derived by the application of the Galerkin weighted-residual procedure.The continuity of the pressure on the interface between fluid and porous medium domains is considered.Laboratory tests were performed to verify the proposed numerical model,and it is shown that the pore-water pressures and the wave heights computed by the VOF-FEM models are in good agreement with the experimental results.It is found that the proposed model is effective in predicting the seabed-nonlinear wave interaction and is able to handle the wave-breakwater-seabed interaction problem. 相似文献
10.
Experimental Study on Vortex-Induced Vibrations of Submarine Pipeline near Seabed Boundary in Ocean Currents 总被引：2，自引：3，他引：2
1 .IntroductionThe submarine pipeline is a commonfacility widely usedfor offshore oil and gastransport . Whena pipeline is installed on a seabed and not buried,unsupportedspans may exist insomelocations ,es-peciallyinthe uneven zones of the seabed.The spa… 相似文献
11.
Shen Ruifu Wang Hongjin Zhou Jinxing Zhou Keji
Former graduate student of Tsinghua University now works in Nanjing Hydraulic Research Institute Nanjing
Professor Tsinghua University Beijing
Senior Engineer Tsinghua University Beijing 《中国海洋工程》1994,(4)
- The cyclic rotation of principal stress direction with a constant amplitude is the characteristics of cyclic stress in seabed deposit induced by travelling waves. Presented in the paper are the results obtained from tests simulating the cyclic stress characteristics, with emphasis laid on the buildup of pore water pressure in soil samples. Regression analysis of test data shows that the pore water pressure can be expressed as the function of the number of cycles of cyclic loading, or as the function of generalized shear strain. Using the results thus obtained, the possibility of failure of seabed deposit under cyclic loading induced by travelling waves can be evaluated. The comparison with the results of conventional cyclic torsional shear tests shows that neglect of the effect of the cyclic rotation of the principal stress direction will result in considerable over-estimation of the stability of seabed deposit. 相似文献
12.
Hyung-suk HAN 《中国海洋工程》2003,17(3)
1 .IntroductionOnthedeepseabed ,30 0 0～ 50 0 0mbelowthePacificOcean ,manganesenodulesaresolidifiedandspread ,andmanycountriesintheworldarestudyinghowtominethem .AccordingtoYamazakietal.( 1 998)andAmannetal.( 1 991 ) ,theenvironmentofthedeepseabedisdifferentfromthedrylandinmanyways .Inparticular,thesurfaceoftheseabedisverysoft.Inordertoensuretheperformanceofrunningofamanganesenodulemineronsuchasoftsurface ,thetrackedvehiclemaybeapplied .Ac cordingtoHongandChoi ( 2 0 0 1 ) ,astudyisbeingdone… 相似文献
13.
Chen-Yuan CHEN John Rong-Chung HSU Cheng-Wu CHEN Ming-Hung CHENG 《中国海洋工程》2006,20(2):303-313
1.IntroductionIn mathematics and physics,a soliton is a self-reinforcing solitary wave caused by nonlinear ef-fectsinthe medium.Solitons are found in many physical phenomena(Chou and Shih,1996;Chouand Quyang,1999;Chouet al.,2003;Chenet al.,2004;Wang,2004;… 相似文献
14.
P. Dewangan T. RamprasadM.V. Ramana A. MazumdarM. Desa F.K. Badesab 《Marine and Petroleum Geology》2010
Increased oil and gas exploration activity has led to a detailed investigation of the continental shelf and adjacent slope regions of Mahanadi, Krishna–Godavari (KG) and Cauvery basins, which are promising petroliferous basins along the eastern continental margin of India. In this paper, we analyze the high resolution sparker, subbottom profiler and multibeam data in KG offshore basin to understand the shallow structures and shallow deposits for gas hydrate exploration. We identified and mapped prominent positive topographic features in the bathymetry data. These mounds show fluid/gas migration features such as acoustic voids, acoustic chimneys, and acoustic turbid layers. It is interesting to note that drilling/coring onboard JOIDES in the vicinity of the mounds show the presence of thick accumulation of subsurface gas hydrate. Further, geological and geochemical study of long sediment cores collected onboard Marion Dufresne in the vicinity of the mounds and sedimentary ridges shows the imprints of paleo-expulsion of methane and sulfidic fluid from the seafloor. 相似文献