基于相位余弦分区的人造地震动反应谱拟合

为解决人造地震动拟合时出现的经幅值调整仍未收敛的问题,分析了造成相位调整效果不稳定的原因并给出有关参数的补充公式,提出由地震动各分量反应对应的相位余弦符号来实现相位分区并给出各分区的相位调整方法.针对经相位调整仍无法收敛情况,在相位调整完成后继续使用幅值调整来改善拟合效果.算例表明本方法可有效实现迭代收敛并生成较好拟合...     

磁法和重力测量基点网平差计算方法探讨

通过公式推导和举例说明,介绍一种高精度磁法测量和重力测量基点网平差的计算方法。此方法简便快捷,并且能更好地应用计算机进行平差计算。     

伽师及其邻近地区重力场动态演化特征初步分析

通过对伽师及邻近地区2005~2007年5期流动重力测量资料的系统分析,研究了该区域重力场的时空动态演化特征。结果表明,重力变化与构造环境变化有关,地震孕育发生阶段,重力场将有明显的异常变化。地震多发于重力变化正负值交替的零线附近,正负重力异常变化梯度带的附近是物质增减差异剧烈的地区,能量易于积累,从而产生地震。与GPS观测结果相互印证,表明受大的构造背景影响,测区内重力异常的正负值分布反映了区域间的应力挤压作用。     

Merging multiple precipitation sources for flash flood forecasting

We investigated the effectiveness of combining gauge observations and satellite-derived precipitation on flood forecasting. Two data merging processes were proposed: the first one assumes that the individual precipitation measurement is non-bias, while the second process assumes that each precipitation source is biased and both weighting factor and bias parameters are to be calculated. Best weighting factors as well as the bias parameters were calculated by minimizing the error of hourly runoff prediction over Wu-Tu watershed in Taiwan. To simulate the hydrologic response from various sources of rainfall sequences, in our experiment, a recurrent neural network (RNN) model was used.

The results demonstrate that the merged method used in this study can efficiently combine the information from both rainfall sources to improve the accuracy of flood forecasting during typhoon periods. The contribution of satellite-based rainfall, being represented by the weighting factor, to the merging product, however, is highly related to the effectiveness of ground-based rainfall observation provided gauged. As the number of gauge observations in the basin is increased, the effectiveness of satellite-based observation to the merged rainfall is reduced. This is because the gauge measurements provide sufficient information for flood forecasting; as a result the improvements added on satellite-based rainfall are limited. This study provides a potential advantage for extending satellite-derived precipitation to those watersheds where gauge observations are limited.     

陇南地区房屋震害调查与易损性矩阵的建立

汶川地震后,作者赴陇南文县、武都区、康县、成县等地详细调查了房屋建筑的震害情况。在整理分析了大量现场第一手资料后,分别建立了各类房屋的地震易损性矩阵,并列举了一些典型震害现象,可为汶川地震后灾区的重建工作提供一定的参考。     

风的垂直切变对滞弹性大气中静力适应过程的影响

本文基于描写滞弹性大气静力适应过程的线性方程组,从波动频散关系、气团运动规律和能量转换的角度出发,研究了水平基流及其垂直切变对该模式大气静力适应过程的影响.构造四种水平基流垂直分布模型进行比较,分别为常数型、线性切变型、反气旋切变型和气旋切变型,得到结论：（1）具有重力波性质的波动是滞弹性大气静力适应过程中扰动能量传播的方式,当垂直折射指数大于零时,基本气流及其垂直切变的存在,不仅改变了波动频率的大小,而且改变波动传播的方向;（2）在静力适应过程中气块的运动轨迹呈椭圆形,水平基流及其垂直切变影响椭圆的扁率,同时也影响扰动物理量之间的偏振关系;（3）水平基流的垂直切变是扰动能量和水平基流能量发生转换的媒介,当存在垂直向上的动量输送时,正的垂直风切变对应扰动能量的衰减,水平基流能量的增加,负的垂直风切变对应扰动能量的增加,水平基流能量的衰减;（4）不同的风的垂直切变模型,对静力适应过程的影响不同;对于水平基流呈反气旋切变型和气旋切变型,扰动发展的波动垂直结构为,急流轴上方波动等相位线自下而上向西倾斜,急流轴下方波动等相位线自下而上向东倾斜,反之亦然.

     

基于附加参数模型的自检校光束法区域网平差算法运行结果对比

像点偏移是影响光束法区域网平差结果精度的主要因素之一。克服平差过程中像点偏移的影响,以提高区域网平差精度,一直受到业界高度重视。当前,克服像点偏移的常规做法是借助特定的参数模型对其进行描述,构建基于附加参数模型的自检校光束法区域网平差模型,在区域网平差的同时求解引入的参数,进而实现对系统误差的补偿。Bauer模型、Ebner模型、Brown模型、光学畸变模型是现有算法中描述像点偏移的常用模型。为了对上述4种模型的系统误差进行验证,本文首先在经典的光束法区域网平差模型基础上分别设计了与4种模型相对应的自检校光束法区域网平差模型,并予以编程实现;然后通过实例对上述4种模型的算法运行结果进行了验证、比较及分析。试验结果表明,Ebner模型和Brown模型的引入可有效提高光束法区域网平差的精度;Bauer模型的引入对小型区域网平差精度的提升更加有效;光学畸变模型的引入对区域网平差结果的精度提升作用相对较小。     

附加傅里叶补偿项的卫星遥感影像RFM平差方法

卫星光学遥感影像的几何畸变是制约其定位精度的重要原因。采用一般系统误差补偿模型难以从根本上消除影像复杂畸变。本文在有理函数模型RFM平差方案基础上,根据傅里叶级数的逼近特性,提出用二元傅里叶多项式代替一般多项式作为系统误差补偿项,以适用符合连续条件的任意形式畸变。仿真和实际数据平差试验结果表明,本文方法能够有效补偿由于影像内外方位元素误差造成的像方定位系统误差及不同大小的畸变。在控制点充足的条件下,附加3阶傅里叶补偿项的RFM平差定位精度显著优于附加一般多项式补偿项的常规方法,其中SPOT-5异轨立体像对平差后平面和高程定位精度可分别达到3.34 m和2.48 m,QuickBird同轨立体像对平差后平面和高程定位精度分别达到0.77 m和0.54 m,均达到了子像素精度水平。二元傅里叶多项式可作为一种通用的影像系统误差补偿模型,拓展应用于航空和近景影像的畸变校正。     

GPS拟合高程在山地1:10000像控测量中的应用

介绍了测量中常用的高程系统概念,GPS高程拟合的方法和适用范围,通过实例分析和探讨在高程异常变化剧烈的地区GPS拟合高程满足1:10 000像控测量精度要求的一些方法.     

Making a photomap of the human eye based on the spherical shape of its sclera and the circular contour of its iris

Iridology was defined as a method of diagnostic used in alternative medicine to analyze health status by studying colors, marks and signs in the sclera of the eye which according to iridologists can be demarcated into zones corresponding to parts of the human body. These are then made into “iridology charts” for comparison with photo images of a patient’s eyes. Due to the large tilt angles of the images relative to the eye’s geometrical axis, accurate comparison is not possible, and this paper suggests the use of photogrammetric methods for making a photomap for each of the patient’s eyes which is then compared to its respective iridology chart. Because of the small overlapping area between any two successive images (about 20%) and the lack of control points, we were prevented from using conventional photogrammetric methods and instead had to develop an alternative photogrammetric method based on the spherical shape of the sclera and the circular shape of the iris contour. Accuracy tests showed that this method is relatively accurate and has small residuals following the process of bundle adjustment.