大深度载人潜水器低速大漂角模糊滑模航向控制研究   总被引：1，自引：0，他引：1  

马岭  崔维成 《海洋工程》2006,24(3):74-78

通过模型试验测量大深度载人潜水器低速大漂角运动时所受到的非线性水动力。基于一种新的模糊滑模控制策略,为潜水器设计了鲁棒航向控制器。在不同的漂角子区间内分别设计局部镇定的滑模控制器,然后通过Takagi-Sugeno模糊推理系统将它们光滑连接,得到模糊滑模控制。仿真计算结果充分显示了该控制策略的有效性。  相似文献   

Monitoring of equivalent beam angles of hull-mounted acoustic survey transducers in the period 1983-1995     

Reynisson  P. 《ICES Journal of Marine Science》1998,55(6):1125-1132

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16米风化砂回填地基的深层振密加固     

曹永琅  张光蒲  丛健 《海岸工程》2001,20(4):21-26

结合北方某重力式深水 ( -1 6.0 m)码头沉箱后壁 1 4.5 m范围的回填风化砂经深层振密处理这一工程实例 ,介绍了回填砂振密的技术要求、施工工艺和方法及振密效果的检测。同时对施工与检测中的某些技术问题提出了自己的看法。  相似文献   

神舟四号高度计波形数据预处理和信息提取   总被引：1，自引：0，他引：1  

纪永刚  张杰  张有广  孟俊敏 《海洋与湖沼》2007,38(6):487-494

神舟四号(SZ-4)高度计在国内首次提供了星载雷达高度计回波波形数据.本文中作者分析了SZ-4高度计回波波形的特点,完成波形数据的预处理,并在此基础上完成初步的信息提取.在数据预处理方面,通过SZ-4高度计水陆边界处波形的特点,提出了波形最大幅度控制的方法,筛选回波波形.在波形归一化处理过程中,发现SZ-4高度计波形中存在双峰现象,并指出第二个峰为异常波形区.在波形信息提取方面,利用波形重新跟踪得到的半功率点计算出SZ-4高度计高度跟踪补偿误差,并根据高度计天线指向角和回波波形下降沿斜率之间的关系,从波形后沿提取天线指向角信息.分析结果表明,SZ-4高度计天线指向比较平稳,而跟踪补偿由于变化较大,在计算海面高度时,应作为一项误差源被考虑到.  相似文献   

Stability of waterfront retaining wall subjected to pseudo-static earthquake forces     

Deepankar Choudhury  Syed Mohd. Ahmad 《Ocean Engineering》2007,34(14-15):1947-1954

Waterfront retaining walls supporting dry backfill are subjected to hydrostatic pressure on upstream face and earth pressure on the downstream face. Under seismic conditions, if such a wall retains a submerged backfill, additional hydrodynamic pressures are generated. This paper pertains to a study in which the effect of earthquakes along with the hydrodynamic pressure including inertial forces on such a retaining wall is observed. The hydrodynamic pressure is calculated using Westergaard's approach, while the earth pressure is calculated using Mononobe-Okabe's pseudo-static analysis. It is observed that when the horizontal seismic acceleration coefficient is increased from 0 to 0.2, there is a 57% decrease in the factor of safety of the retaining wall in sliding mode. For investigating the effect of different parameters, a parametric study is also done. It is observed that if φ is increased from 30° to 35°, there is an increase in the factor of safety in the sliding mode by 20.4%. Similar observations were made for other parameters as well. Comparison of results obtained from the present approach with [Ebeling, R.M., Morrison Jr, E.E., 1992. The seismic design of waterfront retaining structures. US Army Technical Report ITL-92-11. Washington DC] reveal that the factor of safety for static condition (k_h=0), calculated by both the approaches, is 1.60 while for an earthquake with k_h=0.2, they differ by 22.5% due to the consideration of wall inertia in the present study.  相似文献   

Outer wave number spectrum and statistical distribution of apparent wave number vector     

J. -B. Song  K. -J. Wu  Y. -H. Wu 《Ocean Engineering》2003,30(3):401-412

Based on the ray theory and Longuet-Higgins’s linear model of sea waves, the joint distribution of wave envelope and apparent wave number vector is established. From the joint distribution, we define a new concept, namely the outer wave number spectrum, to describe the outer characteristics of ocean waves. The analytical form of the outer wave number spectrum, the probability distributions of the apparent wave number vector and its components are then derived. The outer wave number spectrum is compared with the inner wave number spectrum for the average status of wind-wave development corresponding to a peakness factor P = 3. Discussions on the similarity and difference between the outer wave number spectrum and inner one are also presented in the paper.  相似文献   

Swimming behaviour and target strength of isada krill (Euphausia pacifica)   总被引：1，自引：0，他引：1  

Miyashita  Kazushi; Aoki  Ichiro; Inagaki  Tadashi 《ICES Journal of Marine Science》1996,53(2):303-308

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好望角附近海域春季大风的几种主要形势分析   总被引：1，自引：1，他引：1  

马卫民  陈信雄 《海洋预报》2001,18(2):62-66

通过普查和分析，概括出了春季好望角附近海域三种主要大风出现时的模型图，并以一个月中逐日4次船舶测风报告为例，分析了好望角大风的某些主要特征。  相似文献   

滇西地区地壳上地幔电性结构与地壳构造活动的关系   总被引：46，自引：3，他引：43       下载免费PDF全文

孙洁  徐常芳 《地震地质》1989,11(1):35-45

本文根据滇西地区18个大地电磁测深点资料的数据处理和分析结果,对测区深部导电率在纵、横向上的变化特征进行了研究。结果表明:滇西地区深部电性为多层结构,大致可分四至五个电性结构层;深部电性结构横向变化大,明显受区域构造控制;该区上部地壳内普遍存在低阻层;上地幔高导层明显存在两个隆起区,一个以剑川—鹤庆为中心呈北北西向展布的隆起区,另一个以腾冲—潞西为轴呈南北向展布的隆起区。 本文还讨论了地壳上地幔电性结构与大地构造的关系,滇西北裂陷区盆地的形成,以及该区地震活动与深部构造的关系  相似文献   

频率域电磁法中视电阻率全区定义     

方文藻  李貅  李予国  冯兵 《地球科学与环境学报》1992,(4)

视电阻率定义在电法勘探中得到广泛的应用。目前在频率域电磁法中常常采用远区视电阻率定义。由于在频率域中收发距并非足够大,以致在低频段远区定义视电阻率往往不能反映地下电阻率值。我们定义全区电阻率及引入校正系数K,经二层三层模型及野外实测资料的计算,证明了方法的有效性。  相似文献