An ocean wind-wave climatology for the Southern Brazilian Shelf. Part I: Problem presentation and model validation

Geomorphological features and sparse visual wave measurements, presented in previous works, point out to the possible existence of alongshore wave energy gradients over the Southern Brazilian Shelf (SBS). After describing the two numerical models utilized and the model grids and settings, the present study evaluated the proposed validation of the basin-scale results against orbital altimetry and the regional-scale results against the two available wave-buoy data, discussing the extent to which the model reproduced local reality. The basin-scale model results of significant wave height could be considered as in good agreement with observations, presenting remarkable similarities with observed altimetry. Regarding the regional-scale modeling, both significant wave height and peak wave periods were considered as in good agreement with observations. The peak wave directions, however, were classified as in poor agreement, once the ESE waves were erroneously reproduced as E. Increased spatial resolution certainly played a role, but it was the lowering of bottom friction that represented the major improvement in the coastal grid simulations.     

宁夏惠农区新农村典型供电模式应用研究

针对当前农村电网建设中存在的问题,以宁夏惠农区为试点区域,开展新农村典型供电模式应用研究。分别从电网规划建设、电网运行控制及节能减耗等领域进行供电模式的需求分析,在新农村典型供电模式的基础上提出了惠农区典型供电模式与实施规模,实践表明典型供电模式在惠农区具有较好的应用效果。     

两种网格下的SWAN模式对黄渤海海浪模拟比较

采用NCEP再分析风场作为驱动海浪模式的强迫场,在考虑相同物理过程和分辨率基础上,SWAN海浪模式分别采用矩形网格和非结构三角网格对2000年12月黄渤海海域波浪场进行模拟,并将模拟的有效波高与海洋浮标观测数据作对比分析,结果表明,SWAN模式运用两种网格均能够取得良好的模拟结果,相对矩形网格,非结构三角网格模拟有效波...     

Computations of self-propulsion free to sink and trim and of motions in head waves of the KRISO Container Ship (KCS) model

Two computations of the KCS model with motions are presented. Self-propulsion in model scale free to sink and trim are studied with the rotating discretized propeller from the Hamburg Model Basin (HSVA) at Fr = 0.26. This case is particularly complex to simulate due to the close proximity of the propeller to the rudder. The second case involves pitch and heave in regular head waves. Computations were performed with CFDShip-Iowa version 4.5, a RANS/DES CFD code designed for ship hydrodynamics. The self-propulsion computations were carried out following the procedure described in Carrica et al. [1], in which a speed controller is used to find the propeller rotational speed that results in the specified ship velocity. The rate of revolutions n, sinkage, trim, thrust and torque coefficients K_T, K_Q and resistance coefficient CT_(SP) are thus obtained. Comparisons between CFD and EFD show that the rate of revolutions n, thrust and torque coefficients K_T and K_Q have higher prediction accuracies than sinkage and trim. For the simulation of pitch and heave in head waves, the geometry includes KCS hull and rudder under three conditions with two Froude numbers and three wave length and amplitude combinations. 0th and 1st harmonic amplitudes and 1st harmonic phase are computed for total resistance coefficient C_T, heave motion z and pitch angle θ. Comparisons between CFD and EFD show that pitch and heave are much better predicted than the resistance. In both cases comparisons with simulations by other authors presented at the G2010 CFD Workshop [2] using different CFD methodologies are included.     

基于GIS的姓氏地名制图方法研究

地名研究能够揭示地名所固有的科学价值,为科学研究提供重要依据,地名制图法是地名研究中常用的方法,用它分析姓氏地名可以追述某姓氏起源,了解该姓氏人口的分布、迁移等.本文借助GIS软件,对张姓地名进行了分析,采用的格网制图数据分析,可以反映张姓村庄的密集程度、密度值连续变化状况、宏观分布规律;空间平滑插值制图数据分析,可以...     

基于Midas/GTS的FLAC3D边坡建模技术及工程应用

探讨了如何基于Midas/GTS来实现用FLAC3D建立复杂边坡模型。首先在Midas/GTS中建立几何模型和划分网格,然后根据两种软件的网格数据形式进行转换,把Midas/GTS的网格模型导入FLAC3D中。对于二维边坡问题,认为采用四边形单元比三角形单元的计算精度更高,在模型较为复杂的情况下建议在Midas/GTS中采用四边形+三角形的方式生成混合网格,然后导入FLAC3D中形成brick+wedge形式的混合网格进行分析,以保证计算精度。最后将上述建模方法应用于某边坡工程的稳定性分析,验证了该建模方法的可行性和实用性。     

关于机载LiDAR点云数据形态学滤波的几点思考

形态学滤波是一种典型的机载LiDAR点云数据滤波方法,然而滤波过程中还存在某些容易被忽视的细节.本文在回顾现有各种形态学滤波算法的基础上,分析了特殊地形下点云数据内插存在的问题,提出了改进的内插算法;深入探讨了两种不同数据组织形式的滤波算法,指出基于不规则离散点和基于规则格网两种滤波方法各自的优势及不足;最后通过实验数据对两种方法在滤波性能和效率上给出了定性分析和定量评价.     

Matlab环境下瑞利波有限差分正演与曲线绘制

以瑞利波频散方程为出发点的Abo-Zena传递矩阵等方法,只能研究层状介质中瑞利波的传播特性,对于非层状介质,传递矩阵无能为力。因此,不得不考虑有限元、有限差分等方法。根据弹性动力学方程,采用交错网格有限差分方法对均匀弹性半空间介质进行全波场模拟,并在Matlab环境下实现编程计算,再现了瑞利波在近地表的传播状态,实现了地震剖面曲线的正振幅充填问题,从而获得了类似野外地震勘探的剖面记录。模拟结果表明,采用一阶差分格式所得到的地震记录存在较严重的数值频散,在采用有限差分法研究瑞利波"之"字形成因时,须尽量压制数值频散现象,才能获得更接近实际情况的频散曲线。      

电性参数分块连续变化二维MT有限元数值模拟

为了易于模拟野外复杂地形和地下任意形状地电体模型,将有限元单元网格设计为三角单元;并考虑到野外实际勘探中,地球介质的电性参数均是连续变化的情况,单元内的场值和电性参数被设计为双线性变化;推导出二维起伏地形条件下大地电磁法有限元数值模拟算法;根据单元节点主场值和线性插值形函数间的关系,计算出单元节点的辅助场值;在二维起伏地形情况下,定义TE、TM模式视电阻率和阻抗相位.4个模型的计算的结果与解析法的均方根误差小于1%,地形模拟与前人的计算结果相符,模拟倾斜界面异常体,能有效的反映出其异常形态.     

Petrology of phlogopite-sapphirine-bearing Al-Mg granulites from Ihouhaouene, In Ouzzal, Hoggar, Algeria: an example of phlogopite stability at high temperature

Al-Mg granulites, with cordierite, garnet, sapphirine, orthopyroxene, sillimanite, spinel, phlogopite, K-feldspar, plagioclase and variable quartz from Ihouhaouene (In Ouzzal, Algeria), display a range of decompression textures involving the breakdown of orthopyroxene and sillimanite, and of garnet. The succession of parageneses suggests that the P–T–t evolution corresponds to decompression with cooling from peak conditions of about 950°C and 10 kbar. This decompression path is obtained from the paragenetic analysis in the FMAS system. However, according to current KFMASH grids, this P–T–t evolution should take place outside the stability field of phlogopite+quartz; yet this assemblage is probably stable during most of the P-T evolution, notably during peak metamorphism. This discrepancy is interpreted as the effect of the high content of F in phlogopite which should shift its stability limit towards higher temperature. The consequences of this shift on the phase relationships in the KFeMASH system are investigated and it is concluded that a topological inversion could exist in the F-bearing system.