蒸发波导环境下风浪对电磁波传播影响的数值模拟研究     

闫西荡  杨坤德 《海洋与湖沼》2020,51(1):13-19

蒸发波导是一种特殊的大气波导,在其中传播的电磁波信号会被陷获在近海大气层中,实现超视距传播。受海表面温度、湿度、风速、微波频率等因素的影响,海洋蒸发波导环境中的微波传播特性起伏变化很大,规律十分复杂。以往的工作主要通过计算这些气象因素对蒸发波导条件下大气折射率剖面的影响来分析它们对路径损失的作用,其结果与实验数据仍有较大差异。本文在一定的蒸发波导条件下,利用一维分形海面模型产生海面“地形”,将其作为抛物方程电磁波传播模型的边界条件进行计算,得到相应的路径损失,并与传统计算方法进行对比,分析了不同蒸发波导高度、不同频率及不同接收天线高度时的数值模拟情况,可为舰艇通信系统或者雷达系统的设计提供相应的依据。  相似文献   

基于模拟退火算法的饲料配方设计     

陈世希  李翠华  王渊源 《台湾海峡》2001,20(Z1):142-147

本文在饲料配方设计中首次引入新颖、高效的组合优化算法--模拟退火算法，并获得理想的数值结果，说明了在传统的饲料配方设计中高技术的应用可以获得更高的效益.  相似文献   

A Compact Explicit Difference Scheme of High Accuracy for Extended Boussinesq Equations     

周俊陶林建国  谢志华 《中国海洋工程》2007,21(3):507-514

Presented here is a compact explicit difference scheme of high accuracy for solving the extended Boussinesq equations.For time discretization,a three-stage explicit Runge-Kutta method with TVD property is used at predicting stage,a cubic spline function is adopted at correcting stage,which made the time discretization accuracy up to fourth order;For spatial discretization,a three-point explicit compact difference scheme with arbitrary order accuracy is employed.The extended Boussinesq equations derived by Beji and Nadaoka are solved by the proposed scheme.The numerical results agree well with the experimental data.At the same time,the comparisons of the two numerical results between the present scheme and low accuracy difference method are made,which further show the necessity of using high accuracy scheme to solve the extended Boussinesq equations.As a valid sample,the wave propagation on the rectangular step is formulated by the present scheme,the modelled results are in better agreement with the experimental data than those of Kittitanasuan.  相似文献   

Numerical study of the summer temperature decrease induced by the enhancement of estuarine circulation in Fukuoka Bay     

Kazuhiro Aoki  Atsuhiko Isobe 《Journal of Oceanography》2006,62(2):207-217

The Princeton Ocean Model with realistic bottom topography has been used to investigate the summer temperature decrease in the past 25 years in Fukuoka Bay. The vertical mixing of the model is expressed by a scheme that effectively includes the influences of interannual variations of tidal currents and wind. The results show that the historical temperature decrease in summer has been caused by tidal currents and wind weakening in the past 25 years in Fukuoka Bay. The weakening of tidal currents and wind gives rise to weakening of the vertical mixing, and to enhancement of the estuarine circulation in the bay. The enhancement of the estuarine circulation activates the inflow of open-ocean water toward Fukuoka Bay. Coastal water in summer has therefore tended to be colder and more saline in the past 25 years. This interannual variation in coastal waters is called “open-oceanization” in this study. On the basis of the numerical model, it is anticipated that the temperature will decrease by 0.2°C in the next 25 years in Fukuoka Bay if the tide and wind weaken persistently as in the present bay.  相似文献   

多维联合概率理论对三峡工程设计洪水的计算   总被引：1，自引：0，他引：1  

逯义军  刘德辅  谢波涛  姜云鹏 《中国海洋大学学报(自然科学版)》2007,37(3):497-502,496

首次将多维联合概率理论应用到三峡大坝设计洪水的风险分析,并用随机模拟方法(ISPUD)对四维联合概率分布进行了求解,得出在长江上游干流及主要支流来水量出现的不同组合和最不利组合情况下,相应三峡大坝不同联合重现期的设计洪水。可用于三峡工程的风险分析及防洪调度。  相似文献   

Structural modeling and testing of a concrete canoe     

F. Paradis  G. Gendron 《Ocean Engineering》2007,34(1):206-217

A finite element model is set up and experimental tests are performed to help understand the behavior of a concrete canoe and subsequently optimize its design. First, the performance criteria that must be satisfied to participate at the annual ASCE/Master Builders competition are described. Then, the finite element model and the different loading cases that were studied are presented. Results from these loading cases are discussed and used to optimize the material properties as well as the thickness of the hull and the dimensions of the gunwale and reinforcing ribs. Static and dynamic experimental tests were also conducted to validate the results of the finite element analyses. The results indicate that the main stresses and strains are caused by the static load cases. The additional stresses caused during races are small.  相似文献   

北部湾三维风生流及密度流模拟   总被引：16，自引：0，他引：16  

夏华永  李树华  侍茂崇 《海洋学报》2001,23(6):11-23

将Casulli差分格式引入三维物理海洋模型计算，模拟了北部湾风生流及密度流。模拟结果表明，夏季西南季风在北部湾导致一个顺时针环流，夏季海水密度梯度导致一个逆时针方向的环流，密度流明显强于风生流；冬季东北寒潮导致一个逆时针环流。模拟结果不支持北部湾夏季为一顺时针环流、冬季为逆时针环流的传统结论，而支持终年为逆时针环流的观点。  相似文献   

地震作用下的导管架海洋平台结构动力优化设计研究   总被引：3，自引：1，他引：3  

王兴国  贾默伊周晶 《海洋工程》2003,21(2):16-19

把导管架海洋平台看作钢框架结构，并把优化方法用于结构的抗震设计中；以结构的总重量最小为优化目标，导管的平均直径和壁厚作为设计变量，考虑强度、刚度和稳定等约束条件。通过渤海BZ28—1油田储油平台为例进行了计算，计算结果表明，此方法对海洋平台的设计具有一定的参考意义。  相似文献   

水产饲料膨化机设计刍论     

徐钟良  陈启发 《台湾海峡》2001,20(Z1):207-211

据开发应用水产饲料膨化机实践，初步论述了膨化机生产能力与动力匹配，螺杆设计参数长径比，物料在腔内滞留时间，膨化腔设计及其温度调控，并提出改进设计的见解.  相似文献   

GPS数据采集技术及其在海洋调查中的应用   总被引：1，自引：0，他引：1  

邱雨生  陈敏  刘广山 《台湾海峡》2003,22(3):354-359

本文应用VB6．0开发了智能化的GPS数据采集软件．对该软件的功能进行了简单的介绍，同时对一些关键技术作了较详细的描述。利用该软件、GPS接收机及PC机的组合，可对走航式测量仪器(或移动设备)进行实时定位并保存定位记录，且大大减少一些不必要的数据，使得软件更为实用。  相似文献