Drag Coefficient,Dynamic Roughness and Reference Wind Speed

Surface waves are the roughness element of the ocean surface. The parameterization of the drag coefficient of the ocean surface is simplified by referencing to wind speed at an elevation proportional to the characteristic wavelength. The dynamic roughness is analytically related to the drag coefficient. Under the assumption of fetch limited wave growth condition, various empirical functions of the dynamic roughness can be converted to equivalent expressions for comparison. For datasets covering a wide range of the dimensionless frequency (inverse wave age), it is important to account for the variable rate of wave development at different wave ages. As a result, the dependence of the Charnock parameter on wave age is nonmonotonic. Finally, the analysis presented here suggests that the significant wave steepness is a sensitive property of the ocean surface and a single variable normalization of the dynamic roughness using a wavelength or wave height parameter actually produces more robust functions than bi-variable normalizations using wave height and wave slope.     

西沙湾工程波浪推算及波浪场数值模拟

本研究根据崇武水文站1976—2007年共31 a的波浪观测资料,使用皮尔逊Ⅲ型频率曲线进行拟合分析,推算出崇武在不同重现期条件下的特征波浪要素,再将其作为外海波浪要素输入,通过基于椭圆型缓坡方程的CGWAVE近岸波浪数值模型,模拟西沙湾的重现期波浪场,得到其设计波浪要素,得到较为合理的计算结果。西沙湾的海底地形强烈地影响近岸波浪,导致了波高和波向的不均匀分布特征,岛屿和礁石都是天然屏障,东侧水域受龟屿及闽台码头的掩护,波浪反射、绕射明显,对避风坞起到了有效的保护作用。此外,对于不同地质的边界,反射系数不同使得近岸波高分布有较大差异。     

基于PCL语言的波浪压力自动加载方法

提出了一种基于PCL语言的波浪压力自动加载方法,有效地解决了有限元单元较多时手动加载效率低下的问题,不仅缩短了加载数据的时间,而且避免了数据录入错误的发生,为造船工程师运用频域响应的有限元分析方法对船舶与海洋工程结构物进行结构强度分析创造了条件。     

光通信用IOGHzCMOS八分频器设计

在比较反转触发器（TFF）的各种结构基础上,采用一种单时钟信号控制,实现高速分频的电路结构,设计实现了用于光通信中时钟数据恢复电路的八分频器。该八分频器使用动态负载,输出两路互补信号,采用SMIC0．18um1P6MCMOS工艺,使用Cadence公司的Spectre仿真器进行模拟验证,实验结果证明,在电源电压为1．8V的情况下,该八分频器的工作速度10GHz、功耗仅为4．705mW。     

Validation of Jason and Envisat Altimeter Dual Frequency Rain Flags

New rain flags based on the dual frequency capabilities of the new Jason Poseidon-2 and Envisat RA2 altimeters have been tested, developed and adopted for the operational processing of the altimeter data. Their validation conducted during the calibration/validation phases of the satellites is presented here. The Jason flag is validated by comparison with the TOPEX one, using the Tandem mission. The results show a very good agreement between the two sensors and the two rain flags The Envisat flag is validated by comparison with both Jason and TOPEX using global and collocated data sets. The results show similar performances for the three sensors. The f relations estimated during the calibration-validation period and presented here have been given to the altimeter ground processing facilities for operational use.     

An Experimental Study of Several Special Issues Regarding the Ice Force on Conical Structures

The effect of the cone spacing of a conieal structure on the ice force is studied by model experiments. The ice force reduction coefficient presented in this paper expresses the relationship between the ice force and the arrangement of cones. The experiments prove that the mode of the ice failure before the boundary of upward-downward bending cone (UDBC) is crushing. A conclusion can also be drawn from the experiments that the ice force on the boundary of UDBC is by far less than that on a vertical pile with the same diameter. Moreover, the ice force frequencies on upright and inve-rted cones are obtained under the field condition of the platform JZ20-2, respectively. The results show that the alterna-tion of the ice force on UDBC can hardly induce resonance of platform JZ20-2.     

A Method of Coding and Decoding in Underwater Image Transmission

A new method of coding and decoding in the system of underwater image transmission is introduced, including the rapid digital frequency synthesizer in multiple frequency shift keying,image data generator, image grayscale decoder with intelligent fuzzy algorithm, image restoration and display on microcomputer.     

激光扫描实时获取水下图象信息的方法与系统

报道一种实时大视角、全景深获取水下图象的新方法。该方法试图解决在无人摇控潜器(ROV)和自治式潜器 (UUV)走航式获取水下清晰图象时 ,遇到的激光在水下传输过程中后向散射噪声问题 ,建立了一种具有宽视角、全景深性能的水下激光扫描系统。用这种方法和系统在空气中和水中做了大量的实验 ,并讨论了这种方法和系统的应用前景。     

Application of sequency spectral method to ocean and atmosphere data analysis

I~IOWIn recent years, with the development of the nonlinear science, eSPecially the sea surface remote sensing measurement technology and the probing Of the modern naval science, the effects ofnonlinear coupling interaction have gradually drawn universal attention.But due to the limitation of claSSical frequency spectral method (Bracewell, 1990), it is difficult to characterize the nonlinear coupling inforTnation at higher frequency band. Thus, there havereconed the fundamental pwhleln to …     

水声信道中一种抗多途跳频通信的研究

水声通道系统是当代海洋开发和海洋环境立体监测中的重要技术组成部分，广泛应用于海洋监测、海洋资源勘探和开发等方面。然而，水声信道的随机起伏、时－空－频变的多途特征使水声通信技术成为当代最为复杂的通信技术之一。本文介绍近年来在高速水声通信方面的一些研究进展，讨论了一种利用高速数字信号处理器（DSP）实现水声信道跳频通信的方案，并探讨了该方案在调制信号设计及信号处理实现上所采用的关键技术。