A symmetric time‐domain model for 3D dam–reservoir interaction including radiation damping     

C. Birk  P. Ruge 《地震工程与结构动力学》2007,36(5):661-682

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一维波动方程的近似解及其在浅海声场计算中的应用          下载免费PDF全文

唐应吾 《地球物理学报》1987,30(3):271-280

本文给出一维波动方程的一组近似解,它具有WKB解的简洁性,但又克服了WKB解在反转点附近发散的困难。文中用其结果计算了具有粗糙界面的负声速梯度浅海中的简正波声场。  相似文献   

虚拟球谐方法逼近市级大地水准面计算分析     

王建强  孙云龙 《大地测量与地球动力学》2022,42(2):115-118

研究了构建市级大地水准面的虚拟球谐方法。首先,选择构建区域的中心点和区域半径对观测值进行数据预处理,并统计分析数值范围和位置信息;然后,将观测值由地理坐标系转换到球冠坐标系,再转换到虚拟球坐标系中;最后,根据虚拟球谐方法构建市级大地水准面。以南昌市为例构建采样点,采用多项式拟合和神经网络方法与本文虚拟球谐方法进行比较分析,结果表明,虚拟球谐方法的RMS值为0.308 cm,拟合效果最好。  相似文献   

多层四流球谐函数算法的构建及在大气辐射传输模式中的应用   总被引：1，自引：0，他引：1  

张华  卢鹏 《气象学报》2014,72(6):1257-1268

为了在不大幅度增加计算成本的情况下提高大气辐射传输计算的精度,利用单层四流球谐函数结合多层二流累加法,构造了可用于多层大气的四流球谐函数算法。为了比较与其他辐射传输算法的差异,引入48流离散纵坐标算法作为比较标准,Eddington 近似、四流离散纵坐标算法作为比较对象。在真实大气廓线条件下,计算了晴空和有云大气顶向上辐射通量、地表向下辐射通量以及加热率廓线。得出以下结论：在晴空情况下,与作为标准的48流离散纵坐标法相比,Eddington 近似、四流离散纵坐标法和新构造的四流球谐函数方法加热率绝对误差都小于0?3 K／d;向上、向下辐射通量的相对误差分别小于1％和0?6％。这表明在晴空情况下,3种算法对加热率的计算精度差别不大;对辐射通量的计算精度,两种四流近似算法比传统的 Eddington 近似更为精确。在有云情况下,与48流离散纵坐标法相比,四流球谐函数和四流离散纵坐标法计算的云顶加热率相对误差小于1％,而 Eddington 近似计算的云顶加热率相对误差大于5％。结果表明：新构造的四流球谐函数算法可用于大气辐射传输模式,在不大幅度增加计算成本的同时,提高了晴空大气的整体辐射计算精度和有云大气辐射加热率的计算精度。  相似文献   

多属性直觉模糊容差粗糙集模型     

徐伟华  苑克花  李文涛 《南京气象学院学报》2020,12(3):284-288

在直觉模糊信息系统的背景下提出了基于容差关系的直觉模糊粗糙集模型,从乐观悲观两个角度出发对目标集进行刻画,是对目标集的一种新的逼近方法,同时,可以发现乐观与悲观上下近似的关系.通过求解近似精度可以发现乐观直觉模糊粗糙集模型的近似精度更高.最后给出实证分析,进一步验证结论的有效性.  相似文献   

A meshless method for axisymmetric problems in continuously nonhomogeneous saturated porous media     

《Computers and Geotechnics》2014

A meshless method based on the local Petrov–Galerkin approach is proposed to analyze 3-d axisymmetric problems in porous functionally graded materials. Constitutive equations for porous materials possess a coupling between mechanical displacements for solid and fluid phases. The work is based on the u–u formulation and the incognita fields of the coupled analysis in focus are the solid skeleton displacements and the fluid displacements. Independent spatial discretization is considered for each phase of the model, rendering a more flexible and efficient methodology. Both displacements are approximated by the moving least-squares (MLS) scheme. The paper presents in the first time a general meshless method for the numerical analysis of axisymmetric problems in continuously nonhomogeneous saturated porous media. Numerical results are given for boreholes in continuously nonhomogeneous porous medium with prescribed misfit and exponential variation of material parameters in the excavation zone.  相似文献   

基本气流的垂直切变对热带行星尺度大气波动的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

吴立广 《热带气象学报》1993,9(3):272-275

通过一个赤道β平面上的绝热无摩擦的两层模式,讨论了线性垂直切变的纬向基本气流对热带行星尺度大气波动的影响。在长波近似下,当有纬向基本气流垂直切变时,可得到与东传Kelvin波和西传Rossby波对应的不稳定模态。对不稳定的Kelvin波模态,其相速受垂直切变的影响不大,而对不稳定的Rossby波模态,切变越大,西传速度越小。基本气流的垂直切变主要影响热带Rossby波。  相似文献   

含确定扰动的线性离散时滞系统的前馈-反馈最优控制     

唐功友  郑师  张宝琳 《中国海洋大学学报(自然科学版)》2006,36(6):1008-1012

研究在外界持续干扰的动态特征已知的情况下,线性离散时滞系统的前馈-反馈最优控制问题。给出了前馈-反馈最优控制存在的唯一性条件,提出了前馈-反馈最优控制律的逐次逼近算法;通过截取最优控制序列解的有限项,得到系统的前馈-反馈次优控制律,并利用扰动观测器解决了其物理可实现问题。该算法容易实现,计算工作量小,且对外部持续扰动有良好的鲁棒性。仿真结果说明了算法的有效性。  相似文献   

The role of disaggregated renewable energy consumption on income and load capacity factor: A novel inclusive sustainable growth approach     

《地学前缘(英文版)》2024,15(1):101693

Stimulating renewable energy consumption is a major focus of the Sustainable Development Goals in combating climate change and global warming. The International Energy Agency estimates that renewable energy consumption should be doubled to achieve the COP21 targets. In this context, the question is whether renewable energy types promote the improvement of ecological quality and economic growth. Most studies have investigated the influence of renewable energy on ecological pollution using carbon dioxide emissions or ecological footprint indicators, which only represent the pollution caused by human consumption patterns, and these indicators neglect the supply side. Motivated by this point, this study uses the LCF (Load Capacity Factor) as an environmental indicator and examines the causality relationship among different types of renewable energy, income, and environmental quality in the USA, while also incorporating employment and capital stock into the analysis. Through using the Fourier causality test with the wavelet-decomposed series, the study explores for the validity of the renewable energy-based growth hypothesis and answers to the question of whether there is a causal effect of renewable energy types on environmental quality. The results demonstrate that there is a bidirectional causality between total renewable energy, wood, biomass, and economic growth as well as between these renewable energy types and the LCF.  相似文献