搜索结果: 151-165 共查到“导航设备、水声设备”相关记录243条 . 查询时间(1.174 秒)
螺旋桨空化噪声是舰艇最主要的辐射噪声源。文章分析了螺旋桨噪声平坡形谱曲线的特点，给出源声级谱级曲线的衰减指数值，分析了特征频率和峰值谱级的影响因素。由螺旋桨空化状态下两个特征航速对应的部分频段内的噪声谱级计算式拟合得到水面舰船螺旋桨空化后任意可达航速下的噪声谱曲线。结合叶梢周向速度一定时特征频率处谱级与螺旋桨直径的函数关系和频率一定时叶梢周向速度变化引起的特征频率处谱级变化量，得到潜艇螺旋桨无空化...
An Analysis of X-Band Calibrated Sea Clutter and Small Boat Reflectivity at Medium-to-Low Grazing Angles
X-Band Calibrated Sea Clutter Small Boat Reflectivity Medium-to-Low Grazing Angles
2009/9/3
The coherent temporal characteristics of medium-to-low grazing angle sea clutter and small boat reflectivity are considered for different radar waveforms under a range of environmental conditions and ...
We review experimental evidence for the nonlinearity of sea clutter and the role of the z-parameter or Mann-Whitney rank-sum statistic in quantifying this nonlinear behavior in the context of a hybrid...
Multichannel Along-Track Interferometric SAR Systems: Moving Targets Detection and Velocity Estimation
Multichannel Along-Track Interferometric SAR Systems Moving Targets Detection Velocity Estimation
2009/9/3
Along-track interferometric synthetic aperture radar (AT-InSAR) systems are used to estimate the radial velocity of targets moving on the ground, starting from the interferometric phases, obtained by ...
The Japan Agency for Marine-Earth Science and Technology is developing an automatic bottom inspection and sampling mobile (ABISMO), which is a full-depth rating ROV (Remotely Operated Vehicle) for rea...
Convergence Characteristics of an Acoustic Aplanatic Lens
Convergence Characteristics Acoustic Aplanatic Lens
2009/8/19
An acoustic aplanatic lens is designed by the optical method. It can remove spherical and coma aberrations in the paraxial area. Sound pressure fields of the bi-concave aplanatic lens and a spherical ...
Speed-Up of Acoustic Propagation Program by Time-Domain Difference Method Using a Supercomputer
Acoustic Propagation Program Time-Domain Difference Method Supercomputer
2009/8/19
The FDTD (Finite Difference Time Domain) method is a simple and high-precision numerical method in the underwater acoustic field. For large-scale underwater acoustic field simulations with the FDTD me...
Lumped Parameter Equivalent Circuit Analysis of the Multiport Transducer
Lumped Parameter Equivalent Circuit Analysis Multiport Transducer
2009/8/19
The multiport transducer developed by Dr. J. L. Butler is a novel low-frequency underwater acoustic source using free-flooded resonance cavity chambers with both the inside and outside driving surface...
Focusing Properties of Bicylindrical Acoustic Lenses
Acoustic lens Bicylindrical lens Focusing
2009/8/19
This theoretical report concerns the focusing of a plane progressive acoustic wave by a bicylindrically-curved lens. It was assumed that the lens was made of polymethylmethacrylate (PMMA) and was subm...
基于QFT的船舶航向控制器设计与仿真研究
定量反馈理论（QFT） 船舶航向控制 鲁棒控制器
2009/7/21
论述了基于定量反馈理论（QFT）的船舶航向控制器的设计方法。该方法不仅能保证闭环系统有较强的鲁棒性，还具有良好的动静态特性，特别是在系统的快速性方面较其它设计方法有较大的改善和提高。基于MATLAB的仿真实验表明运用该方法所设计的控制器具有较强的鲁棒性和自适应能力，满足性能指标的要求，具有较高的工程应用价值。
影响船舶雾航安全的人为因素分析及对策
雾航安全 人为因素 主要表现
2009/6/22
海雾是影响船舶航行的不安全因素，本文论述了人为因素在船舶雾航安全中的重要性，分析了影响船舶雾中航行安全的人为因素的主要表现，并提出了消除船舶雾航中不良人为因素的对策。
应进一步完善船舶压载水管理
船舶压载水 航运业
2009/6/19
船舶压载水主要是为确保船舶在空载或不满载情况下的稳性和浮态，而在船舶离港前用海水在其压载舱中打入压载水，并在抵达预定港口装货前，将压载水逐渐排空，以便船舶可以最大限度地装载货物。船舶在打入压载水的同时，也将海洋水生物带入压载舱中，而在另外一处港口的海洋环境中打出压载水，也将这些异地水生物带入另一海洋环境，从而对新的海洋环境的生态造成影响和破坏，有时甚至是致命的破坏。
2009年全国船舶与海洋工程学科博士生学术会议（2009年全国博士生学术会议（船舶与海洋工程））
2009年 全国船舶与海洋工程学科博士生学术会议 全国博士生学术会议 船舶与海洋工程
2009/6/8
“2009年全国船舶与海洋工程学科博士生学术会议”，由国务院学位委员会办公室主办于2009-6-6在武汉理工大学召开，旨在促进船舶与海洋工程学科博士生进行前沿性的学术探讨，为与会博士生开阔学术视野、进行学术交流提供平台。
