Sensitivity of Precipitation in Aqua-Planet Experiments with an AGCM

The sensitivity of precipitation was studied by conducting control aqua-planet experiments(APEs) with a model to determine atmospheric general circulation.The model includes two versions: that with a spectral dynamical core(SAMIL) and that with a finite-volume dynamical core(FAMIL).Three factors were investigated including dynamical core,time-step length,and horizontal resolution.Numerical results show that the dynamical core significantly affects the structure of zonal averaged precipitation.FAMIL exhibited an equatorial precipitation belt with a single narrow peak,and SAMIL showed a broader belt with double peaks.Moreover,the time step of the model physics is shown to affect the zonal-averaged tropical convective precipitation ratio such that a longer time step leads to more production and consumption of convective available potential energy and convection initiated away from the equator,which corresponds to equatorial double peaks of precipitation.Further,precipitation is determined to be sensitive to horizontal resolution such that higher horizontal resolution allows for more small-scale kinetic energy to be resolved and leads to a broader probability distribution of low-level vertical velocity.This process results in heavier rainfall and convective precipitation extremes in the tropics.Abstract The sensitivity of precipitation was studied by conducting control aqua-planet experiments(APEs)with a model to determine atmospheric general circulation.The model includes two versions:that with a spectral dynamical core(SAMIL)and that with a finite-volume dynamical core(FAMIL).Three factors were investigated including dynamical core,time-step length,and horizontal resolution.Numerical results show that the dynamical core significantly affects the structure of zonal averaged precipitation.FAMIL exhibited an equatorial precipitation belt with a single narrow peak,and SAMIL showed a broader belt with double peaks.Moreover,the time step of the model physics is shown to affect the zonal-averaged tropical convective precipitation ratio such that a longer time step leads to more production and consumption of convective available potential energy and convection initiated away from the equator,which corresponds to equatorial double peaks of precipitation.Further,precipitation is determined to be sensitive to horizontal resolution such that higher horizontal resolution allows for more small-scale kinetic energy to be resolved and leads to a broader probability distribution of low-level vertical velocity.This process results in heavier rainfall and convective precipitation extremes in the tropics.     

单层褶皱变形过程中最大主应力与水平应变的变化及其影响因素

对地质构造进行定量半定量研究是地质工作者近几十年来一直努力的方向,构造数值模拟是有效的定量研究方法之一。褶皱是一种典型的构造类型,对褶皱构造进行定量半定量研究也一直是构造地质学家们所致力解决的研究课题。本文结合近年来单层褶皱构造数值模拟研究进展,以及笔者近几年来对单层褶皱所进行的数值模拟实验研究,主要论述了单层褶皱变形的影响因素,单层褶皱变形过程中的最大主应力与水平应变的变化及其影响因素等。数值模拟技术为褶皱变形提供了一种新的研究方法,该方法在构造地质领域将有很好的发展前景。     

临河盆地中部地区地震动高频衰减参数kappa值的研究

kappa值是描述地震动傅里叶幅值谱高频段衰减速率的物理量,其是地震动模拟中的一个重要参数。该研究以临河盆地中部地区为研究区域(N:40°—42°;E:106°—108°),选取2009-2019年盆地内4个强震动台站记录到的16次地震(2≤M_S≤6)26条强震数据,利用Anderson与Hough提出的经典算法(傅氏谱法),将加速度记录的水平方向的分量kappa(E-W)与kappa(N-S)分别研究。利用kappa值的均值(kappa(Mean))与震中距的拟合,发现其存在较为明显的线性关系,估算出临河盆地中部地区的高频衰减参数kappa0值为0.044～0.050 s。利用线性关系斜率k_R,估算临河盆地中部地区180 km范围内的等效品质因子Q值为2 763～3 367。四个台站的kappa值与震中距分布关系与Castro研究意大利翁布里亚盆地kappa值分布关系一致,存在70至100 km内kappa值有慢增长趋势,此结论验证了我们估算的合理性。     

一种从机载LiDAR点云获取建筑物外部轮廓的方法

利用点云的滤波、带距离控制的卷包裹算法以及复杂多边形的简化等一系列的算法对测区的机载LiDAR数据进行运算和处理,最终得到描述建筑物在不同高度时的外部轮廓多边形,为基于影像和辅助数据相结合的遥感影像阴影区域提取方法提供有效的辅助数据源。     

Research on Horizontal Vibration of Heavy-Weight Drill Pipes in Directional Drilling

The mode of load and deformation of directional drilling string and the expression of trigonometric series of deflection equation are established by means of elastic deformation energy and of the vertical and horizontal bending. A calculation formula for natural frequency of horizontal resonance and rotational speed is derived based on the calculation method by Ritz, with which analysis is made for the cause and affecting factors of the excessive abrasion of heavy-weight drill pipe in high-angle holes so as to provide reference and basis for rational selection of drilling parameters and drilling tools in the future high-angle directional drilling.     

分散滑移模态控制法在高层建筑结构抗震中的应用

分散控制与集中控制策略相比可以提高结构控制系统的可靠性。文中将分散控制和滑移模态控制算法原理相结合,导出分散滑移模态控制(decentralized sliding mode control,DSMC)算法并应用于高层结构振动控制中。该方法是将结构分解为若干个子结构,分别进行滑移模态控制。文中以某20层钢结构Benchmark模型为例,分别进行3个子结构与4个子结构的分散控制数值计算,与线性二次型最优控制(Linear quadratic optimal control,LQR)效果相比,DSMC算法可以有效地抑制结构位移和加速度反应。     

潮流能水平轴水轮机湍流模型研究初探

借助计算流体力学(CFD)方法研究潮流能水平轴水轮机水动力学性能,选择合适的湍流模型至关重要。为此,本文采用计算流体力学软件Fluent,将Spalart-Allmaras湍流模型、标准k-ε湍流模型、RNGk-ε湍流模型、标准k-ω湍流模型和SSTk-ω湍流模型分别应用到水平轴水轮机数值模拟当中。对数值模拟结果进行分析比较,并与模型试验数据进行对比,得出应用SSTk-ω湍流模型可以更好的模拟潮流能水平轴水轮机的水动力学性能。     

鸟瞰航摄历史遗迹景观的技术分析

介绍了国内利用超轻型飞机航空摄影考古的首次试验,通过对历史遗迹的分析,取得良好的应用效果。本次试验采用国产的超轻型飞机蓝鹰AD-200Y型,携带常规照相机,在内蒙古自治区以呼和浩特市为中心的局部地区,进行20个架次飞行,从低航空高度环绕历史遗迹,多角度视野,进行航拍鸟瞰地表历史遗迹景观照片799张。这些照片反映历史遗迹的整体面貌,是地面田野考古无法做到的事。为考古研究提供了不可多得的资料。其技术工艺流程：①确定历史遗迹项目；②地形图分析历史遗迹基础地理环境(地理位置,地形地貌)；③分析交通气象状况；④航空摄影技术设计；⑤超轻型飞机技术完善；⑥照相机和胶卷选型；⑦拟定飞行安全措施；⑧飞行基地起降跑道选择；⑨航摄飞行实施和指挥；⑩历史遗迹鸟瞰景观数字化图像分析。     

潮汐能量耗散与地月系统演化

对地月系统而言, 在很大程度上角动量守恒是正确的. 地月距离的变化主要是受到月球引起的潮汐能量耗散的影响. 根据月球的平均运动和它的长期加速度, 就可以计算出月潮能量耗散的数值. 海洋是潮汐能量耗散的主要区域. 由于潮汐的高度正比于月球对潮汐隆起的万有引力, 由此可导出总的月球潮汐摩擦力正比于月球平均运动的平方. 如果采用月球平均加速度数值-20.72$''\cdot$cy^-2, 就可以推算出35亿年来地月之间的距离以及回归年日数和朔望月日数的演化. 此理论结果与古生物钟的数据进行比对, 两者符合较好.     

Large-scale motion of solar filaments

Precise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.