Numerical Simulation for Refraction-Diffraction of Waves in Water of Slowly Varying Current and Topography

A new numerical finite difference iteration method for refraction-diffraction of waves in waterof slowly varying current and topography is developed in this paper.And corresponding theoretical modelincluding the dissipation term is briefly described,together with some analysis and comparison ofcomputational results of the model with measurements in a hydraulic scale model(Berkhoff et al.,1982).An example of practical use of the method is given,showing that the present model is useful to engineeringpractice.     

DEFORMATION AND ROUGHNESS CHANGES OF THE MAIN CHANNEL AND FLOODPLAIN IN FLOOD EVENTS (CASE STUDY )

LINTRODUCTIONAsfear7specificsurveyshavebeenmadeonthemorphologicalbehavioroftheHuaihefox'erinthepast.Someinformationofbeddeformationduringfloodprocesshavebeenobtained.Beingrelativelystable,theHuaihehiverusedtobeineptlytreatedas"fixedbed".Fortunately,tilehydrometricalstationsweredenselydistributedalongtheHuaihehiverinthe1950s,andthevelocitylareamethodwasusedforthedeterminationofdischarge.Themeasurementsofdischargearelistedin"TheDischargeMeasurementsTable"intheHydrologicalYearbooks.Sinc…     

基于GOCE梯度的地球引力场恢复(英文)

Given the second radial derivative Vr r ( P ) |S of the Earth’s gravitational potential V ( P ) on the surface S corresponding to the satellite altitude, by using the fictitious compress recovery method, a fictitious regular harmonic field rrVr r( P )* and a fictitious second radial gradient field Vr *r ( P) in the domain outside an inner sphere K i can be determined, which coincides with the real field Vr r( P ) in the domain outside the Earth. Vr *r ( P)could be further expressed as a uniformly convergent expansion series in the domain outside the inner sphere, because rrVr r( P )* could be expressed as a uniformly convergent spherical harmonic expansion series due to its regularity and harmony in that domain. In another aspect, the fictitious field V * ( P) defined in the domain outside the inner sphere, which coincides with the real field V ( P ) in the domain outside the Earth, could be also expressed as a spherical harmonic expansion series. Then, the harmonic coefficients contained in the series expressing V * ( P) can be determined, and consequently the real field V ( P ) is recovered. Preliminary simulation calculations show that the second radial gradient field Vr r( P ) could be recovered based only on the second radial derivative Vr r ( P )| S given on the satellite boundary. Concerning the final recovery of the potential field V ( P ) based only on the boundary value Vr r ( P )|S, the simulation tests are still in process.     

地球的时变主惯性矩和变化的自转(英文)

Based on the gravity field models EGM96 and EIGEN-GL04C, the Earth's time-dependent principal moments of inertia A, B, C are obtained, and the variable rotation of the Earth is determined. Numerical results show that A, B, and C have increasing tendencies; the tilt of the rotation axis increases 2.1×10-8 mas/yr; the third component of the rotational angular velocity, ω 3, has a decrease of 1.0×10-22 rad/s2, which is around 23% of the present observed value. Studies show in detail that both θ and ω 3 experience complex fluctua-tions at various time scales due to the variations of A, B and C.     

Integrated Futures for Europe’s Mountain Regions: Reconciling Biodiversity Conservation and Human Livelihoods

Introduction Europe's mountains cover nearly half of the continent's area (Price et al. 2004) and land cover varies significantly (European Commission 2004). In most massifs, except for Sicily, southern Greece, and the British Isles, forest cover is dominant. In northern Europe, grassland is proportionately more important, and much of the mountains of the British Isles is covered by moorland. In central and southern Europe, arable land is of far greater importance than grassland, with Med…     

遥感影像正射纠正的GPU-CPU协同处理研究

提出了一种基于CUDA的遥感影像正射纠正GPU-CPU协同处理方法,以实现重采样操作的GPU细粒度并行化。根据GPU的并行结构和硬件特点,采用执行配置优化技术提高warp占有率,利用共享存储器优化减少对效率低下的全局存储器中坐标变换系数的重复访问,通过纹理存储器代替全局存储器优化对原始影像数据的访问。实验结果表明,并行算法能够充分发挥GPU的并行处理能力,利用GeForce 9500 GT显卡,对大小为6 000像素×6 000像素的全色影像进行多项式纠正对比实验,最邻近灰度内插重采样和双线性灰度内插重采样的最终加速比分别能够达到8倍和10倍以上。     

剩余视极化率异常在寻找焦家式深部金矿床的应用研究

本文首次提出剩余视极化率异常的概念和求 取公式。利用已知焦家式深部金矿床上所 测得大、 小两种极距激电中梯视极化率ηα,而求得的剩余视 极化率ηαsy,经与已知深部矿床对比,发现其ηαsy异 常具有单纯反映矿体的能力,而与破碎带内的强蚀 变岩石所形成的极化率异常无关。     

地图模糊矩阵模型与制图术语表述数学化研究

笔者在过去所研究地图模糊矩阵模型的基础上,进一步探讨了建立地图模糊矩阵模型问题,通过矩阵运算来对地图学中有关制图综合、图象变换等概念给出了数学定义,从而使概念表述数学化。     

微机地图图形工作站上地图数字化子系统的设计与实现

借助于微型计算机而建立的地图图形工作站其目的在于完成数字化地图生产,即从地图数据的获取、管理、编辑、更新到图形输出等一系列过程。而地图数字化子系统则是该工作站上完成数据获取这一最初也是最重要过程的软件系统。文中介绍了笔者研制的地图图形工作站上的地图数字化子系统。该系统是在自行设计和研制的地图图形工作站的总框架下完成的,现已具备数字地图产业化生产能力,能有效地配合工作站完成数字地图的生产。同时,该系统对于不同的数据获取途径以及诸如我国地(形)图的独特要求(如汉字注记的处理)等方面有良好的适应性。     

一种消除stokes积分卷积化近似误差影响的有效方法

在应用快速Hartly变换(FHT)或快速Fourier变换(FFT)计算Stokes积分公式时,总是先将Stokes 公式化成卷积形式,然后用 FHT或 FFT完成卷积运算,从而避免了复杂费时的积分计算。但由于 Stokes公式不严格满足卷积定义,欲将其化成卷积形式必须作一些近似。这种近似虽能在一定精度范围满足要求,但对于高精度要求仍有不能允许的计算误差。本文建议采用球面坐标转换方法,能有效地消除无论是用 FHT或 FFT 计算Stokes 积分卷积化所带来的误差影响。