基于间断有限元方法的三维近岸波生流数值模型建立

在三维水动力模型中引入三维辐射应力,水滚影响以及波浪附加紊动效应,并基于间断有限元方法建立了非结构化网格三维波生流数值模型。采用实验室内斜坡地形条件下正向入射波在破波带附近产生的近底回流和斜向入射波产生的沿岸流对模型进行了验证。结果表明,计算值与实测值吻合程度较好,该模型可以较好地描述三维近岸波生流。     

不同结构型式及高程离岸潜堤投射系数实验研究

针对威海九龙湾岸滩治理工程,进行不同结构型式及不同高程离岸潜堤的物理模型试验。根据物理模型试验的结果,得出离岸潜堤透射系数Kt与主要影响因子的相互关系。得出影响潜堤透射系数最主要的因子为相对堤顶水深(a/Hi),在一定水位条件下,相对堤顶长度(B/L)也能影响透射系数。借助MATLAB数学软件平台,将数据进行回归分析,得出不规则波作用下潜堤透射系数的经验公式,为此类工程设计提供参考。     

Numerical investigation of the hydrodynamic interaction between two underwater bodies in relative motion

The hydrodynamic interaction between an Autonomous Underwater Vehicle (AUV) manoeuvring in close proximity to a larger underwater vehicle can cause rapid changes in the motion of the AUV. This interaction can lead to mission failure and possible vehicle collision. Being self-piloted and comparatively small, an AUV is more susceptible to these interaction effects than the larger body. In an aim to predict the manoeuvring performance of an AUV under the effects of the interaction, the Australian Maritime College (AMC) has conducted a series of computer simulations and captive model experiments. A numerical model was developed to simulate pure sway motion of an AUV at different lateral and longitudinal positions relative to a larger underwater vehicle using Computational Fluid Dynamics (CFDs). The variables investigated include the surge force, sway force and the yaw moment coefficients acting on the AUV due to interaction effects, which were in turn validated against experimental results. A simplified method is presented to obtain the hydrodynamic coefficients of an AUV when operating close to a larger underwater body by transforming the single body hydrodynamic coefficients of the AUV using the steady-state interaction forces. This method is considerably less time consuming than traditional methods. Furthermore, the inverse of this method (i.e. to obtain the steady state interaction force) is also presented to obtain the steady-state interaction force at multiple lateral separations efficiently. Both the CFD model and the simplified methods have been validated against the experimental data and are capable of providing adequate interaction predictions. Such methods are critical for accurate prediction of vehicle performance under varying conditions present in real life.     

基于人工鱼群算法和Pearson相关系数的裂缝属性识别

将人工鱼群算法和Pearson相关系数结合,引入到进行裂缝属性识别的横波分裂方法中。结果表明,本文使用的方法能快速准确地识别裂缝属性,相比于模型空间扫描、粒子群算法及遗传算法等识别方法,收敛速度增快了约3倍,稳定性上也有所提高。     

T63月动力延伸预报产品的检验

采用NCEP／NCAR再分析资料和T63谱模式月动力延伸预报产品资料,对200、500hPa高度场及200hPa、700hPaU、V风场进行相关系数、距平、距平同号率、距平相关系数的分析,得出如下结论：月动力延伸预报产品对极涡、南亚高压、副热带高压预报能力较强,夏季副热带系统预报偏强,西风带系统预报偏弱;冬季西风带系统预报偏强,副热带系统预报偏弱。西风带和副热带系统的距平误差基本反映出影响我国年季气候变化主导系统的进退及预报误差。     

数值流形方法及在川滇地区地壳运动研究中的应用

The numerical manifold method （NMM） can calculate the movements and deformations of structures or materials. Both the finite element method （FEM） for continua and the discontinuous deformation analysis （DDA） for block systems are special cases of NMM. NMM has separate mathematical covers and physical meshes： the mathematical covers define only fine or rough approximations; as the real material boundary, the physical mesh defines the integration fields. The mathematical covers are triangle units; the physical mesh includes the fault boundaries, joints, blocks and interfaces of different crust zones on the basis of a geological tectonic background. Aiming at the complex problem of continuous and discontinuous deformation across the Chinese continent, the numerical manifold method （NMM） is brought in to study crustal movement of the Stchuan-Yunnan area. Based on the GPS velocity field in the Sichuan-Yunnan area, a crustal strain and stress field is simulated and analyzed. Moreover, results show that the NMM is a more suitable method than DDA in simulating the movement of the Sichuan-Yunnan area. Finally, a kind of mechanism of crustal motion in the Sichuan-Yunnan area is discussed in the paper.     

降水对气溶胶粒子清除的参数化

本文主要讨论了碰并系数、雨滴谱和气溶胶谱对湿清除率的影响.在0.1μm相似文献   

北京市大气电场和大气污染物关系初步研究

以北京市朝阳站为例总体上分析了2014-2015年北京市全年、冬半年和夏半年电场强度和污染物变化特性及相关性,重点研究静稳积累型、污染复合型、沙尘型3种类型污染天气下大气电场强度与主要污染物因子浓度以及与气象要素之间的关系.结果表明:(1)全年电场强度每小时平均值为0.45～0.72kV·m-1,全年电场强度主要峰值在...     

华中地区6—7月雨带客观分型及其预报

利用华中地区66个代表站历年降水场的车贝雪夫多项式展开系数,将雨带客观分成强、一般、弱三等和长江以北、长江以南、长江沿岸、南北雨带四个型.在分析前期海平面气压特征基础上,结合普查的前期关键区,指出了关健区实质上是影响雨带的地面大气活动中心异常的反映.以前期关键区的海平面气压为因子试报1991—1992年雨型效果较好.