Fast Evaluation of Time-Domain Green Function for Finite Water Depth     

滕斌  韩凌  勾莹 《中国海洋工程》2003,17(3)

1 .IntroductionShipsrestrainedbycablesandfendersinfrontofdocksundergolargeamplitudenon harmonicmotionsinwaves.Forthiskindofnon harmonicproblem ,atime domainmethodmustbeapplied .LinandYue ( 1 990 )usedanintegralequationwiththetime domainGreenfunctionforinfinitewaterdepthtocomputetheshipmotionindeepwater.Butforthepresentproblem ,theintegralequationwiththetime domainGreenfunctionforfinitewaterdepthmustbeapplied .TheGreenfunctionisafieldwithacertainboundaryandinitialconditionsproducedbyasourceat…  相似文献   

Analysis of Wave Directional Spreading by Bayesian Parameter Estimation     

Hwa  CHIEN 《中国海洋工程》2002,16(1):89-105

A spatial array of wave gauges installed on an observatoion platform has been designed and arranged to measure the lo-cal features of winter monsoon directional waves off Taishi coast of Taiwan. A new method, named the Bayesian Parameter Estimation Method(BPEM) , is developed and adopted to determine the main direction and the directional spreading parame-ter of directional spectra. The BPEM could be considered as a regression analysis to find the maximum joint probability of parameters, which best approximates the observed data from the Bayesian viewpoint. The result of the analysis of field wave data demonstrates the highly dependency of the characteristics of normalized directional spreading on the wave age. The Mit-suyasu type empirical formula of directional spectrum is therefore modified to be representative of monsoon wave field. More-over, it is suggested that Smax could be expressed as a function of wave steepness. The values of Smax decrease with increas-ing steepness. Finally, a local directi  相似文献   

Energy Anaiysis for TMD-Structure Systems Subjected to Impact Loading     

王树青  李华军  嵇春艳  焦桂英 《中国海洋工程》2002,(3)

This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper (TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focuses on the energy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplified single-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force is assumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied. Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the Standard deviation of the deck motion but less effective in reducing the maximum response under impact loading.  相似文献   

Dynamic Risk Analysis of Permanent Deformation of Sea Embankment     

GAO  Yufeng 《中国海洋工程》2001,(1):107-116

For evaluation of the permanent deformation of a sea embankment under stochastic earthquake excitation, a robust dynamic risk analytical method is presented based on conventional permanent deformation analysis and stochastic seismic response analysis. This method can predict not only the mean value of maximum permanent deformation but also the reliability corresponding to different deformation control standards. The earthquake motion is modelled as a stationary Gaussian filtered white noise random process. The predicted average maximum horizontal permanent displacement is in agreement with the conventional result. Further studied are the reliability of permanent deformation due to stochastic wave details at one seismic motion level and the risk of permanent deformation due to stochastic seismic strength, i. e., the maximum acceleration in a long period. Therefore, it is possible to make the optimal design in terms of safety and economy according to the importance of a sea embankment. It is suggested tha  相似文献   

Optimum Design for Offshore Platform Structural Reliability     

Zhu Qixian Senior Engineer  Bohai Engineering  Design Company  Tianjin 《中国海洋工程》1992,(3)

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.  相似文献   

Nonlinear Wave Force on Pier Group in Shallow Water     

Qiu Dahong  Zhou Yuanheng  Jia Ying Professor  Dept. of Civil Engineering  Dalian University of Technology  Dalian Lecturer  Dept. of Civil Engineering  Dalian University of Technology  Dalian 《中国海洋工程》1992,(1)

Based on the 1st order cnoidal wave theory, the wave diffraction around the pier group inshallow water is studied in this paper. The formulas for calculating the nonlinear wave forces are also presented here. In order to verify the theoretical results, model tests are conducted in the wave flume in The State Key Laboratory of Coastal and Offshore Engineering located in Dalian University of Technology. The range of the wave parameters in the experiments is characteristic wave period T g/d~(1/2) = 8.08- 22.86, characteristic wave height H/ d= 0.1 ~ 0.45. The results obtained from the experiments agree with the theoretical results quite well. It is shown that, in shallow water the nonlinear wave forces acting on a pier group are greater than those calculated by linear wave theory, the value of increment in wave force increases with the increases of the nonlinearity of the wave. In the wave range studied in this paper, the nonlinear wave force can reach over 4 times the force calculatecd by linear wave theory. Thus, it is suggested that, when Tg / d~(1/2)> 8, the wave force on the piers in the pier group in shallow water should be calculated by using the cnoidal wave theory.  相似文献   

Wave Breaker Indices in Finite Water Depth   总被引：2，自引：0，他引：2  

Li Yucheng  Dong Guohai Teng Bin Professor  Civil Engineering Department  Dalian University of Technology  Dalian Ph. D. Student  Dalian University of Technology  Dalian Research Assistant  Doctor of Engineering  Dalian University of Technology  Dalian 《中国海洋工程》1991,(1)

Based on the analysis and comparison of wave breaker indices defined by geometric, kinetic as well as dynamic stabilities and verified by observation, the value a, which is equal to H / Lthkd by Miche's result and may be modified by Goda's results, is" suggested as the wave breaking criteria. The applicable values of a for pure waves or wave-current co-existing field are given in this paper. They are smaller than Miche's result (0.142), and they have been verified by model tests.  相似文献   

测井数据小波变换在层序地层分析中的应用研究   总被引：2，自引：0，他引：2  

马飞宙  余继峰鲁静文怀军  肖正辉 《中国煤田地质》2007,19(4):70-73

以柴达木盆地北缘某钻井中侏罗统的层序地层划分为例,对各种一维连续小波在地层划分中的效果进行尝试,发现采用db5小波用于层序划分较为理想。通过利用db5小波对自然伽马测井数据进行连续小波变换,将测井信号与深度的关系转换为与深度及尺度域的变化关系,以此识别出了层序界面。利用该小波变换进行的层序地层划分,与传统方法划分的结果基本一致。  相似文献   

沁水盆地煤与煤层气地质条件   总被引：1，自引：0，他引：1  

冀涛  杨德义 《中国煤田地质》2007,19(5):28-30,61

沁水盆地位于山西省东南部,含煤面积29 500km^2,煤炭储量5 100亿t,为特大型含煤盆地。通过分析沁水盆地煤层埋深、厚度、构造特征、顶底板岩性及煤储层特征,认为该区主要煤层含气量高,煤层割理、裂隙发育,煤变质程度高,煤层厚度大、埋深适度,构造简单,煤层气资源量大,产出条件优良,是我国煤层气勘探开发最有利的地区之一。  相似文献   

Long-period ground motion characteristic of the 1999 Jiji (Chi-Chi),Taiwan,main-shock and aftershocks     

李春锋  张旸  赵金宝  唐晖 《地震学报(英文版)》2006,(4)

Introduction The study of attenuation relations for long-period ground motion is to meet the requirement of economy development. During the earthquakes such as the June 16, 1964 Niigata, Japan, M=7.5 earthquake, the March 24, 1977 Romania M=7.3 earthquake, the March 29, 1970 Gediz, Turkey, M=7.1 earthquake, the May 26, 1983 M=7.7 earthquake in the middle Japanese Sea, the September 19, 1985 Mexico M=8.1 earthquake, the September 16, 1994 M=7.3 earthquake in Tai- wan Strait, and the No…  相似文献