共查询到19条相似文献，搜索用时 140 毫秒
1.
关于非球形粒子光散射的T-矩阵数值计算方法的研究 总被引：1，自引：0，他引：1
首先介绍了无规取向轴对称非球形粒子光散射的T－矩阵数值方法。然后，进一步研究了T－矩阵计算的收敛问题，提出了一种新的关于无规取向无吸收非线形散射物体的物理收敛方法，我们研究了椭球粒子的收敛问题，结果表明我们的数值方法和T－矩阵计算程序是有效的， 收敛精度与粒子的尺度和形状有很强的依赖性，在一定的条件下，我们的物理收敛速度优于NASA Mishchenko的数学收敛速序。 相似文献
2.
用有限长圆柱状模拟小冰晶的非球形性，用T－矩阵理论研究了随机取向小圆柱状冰晶多色粒子光散射的线偏振特征，强调了在红外谱区波长从大气红外短波窗区（λ=3.979μm)到远红外λ=30μm的光散射，考虑了31种粒子的谱分布和10种圆柱状纵横比。广泛的计算结果表明，圆柱状小冰粒在红外谱区的线偏振强烈地依赖于波长和折射指数、粒子的纵横比和谱分布。与文献中类似的工作比较，获得了一些新的和有意义的结果。 相似文献
3.
在非等间距GM(1,1)模型中，系数矩阵中有无误差的常数项和有误差的随机项，并且系数矩阵与观测向量误差同源，即系数矩阵与观测向量中有相同的元素存在，这些相同元素应该有相同的改正数，为此本文推导了一种适合非等间距GM(1,1)模型求解的总体最小二乘算法。同时，考虑到非等间距GM(1,1)模型中存在病态问题时影响总体最小二乘计算结果的稳定性，提出对系数矩阵常数列乘以某一常数的方法，以改善病态问题。 相似文献
4.
廖伟华 《地球信息科学学报》2012,14(4):426-431
GIS属性相似度量有相似系数及以空间位置的空间自相关。这2种方法都不能计算全域为背景的次区域相似性问题,而以隶属函数的粗糙度量很好地解决了这个问题。本文利用粗糙集计算了GIS的离散型数据的次区域相似度量。利用邻域粗糙集计算了连续属性值的上下近似逼近,并利用邻域信息粒子计算连续属性值的粗糙隶属问题,从而计算连续属性值次区域相似度量问题。本文方法能度量次区域而不是全域或单个元素之间的空间相关与自相关问题,考虑了全区域背景下的GIS相似问题。并针对GIS连续属性值,利用距离函数和邻域粗糙集来划分连续属性的上下近似,以及分类问题,提出一种基于邻域信息粒子的粗糙隶属函数。最后利用粗糙相似度量公式度量GIS次区域的相似问题。 相似文献
5.
针对多项式拟合模型系数矩阵中部分元素是某一自变量的函数的特点,根据Partial EIV模型的解算思想,将系数矩阵中自变量的函数作为随机元素提取,顾及泰勒展开的二阶项,由协方差传播律计算自变量函数的协因数阵进行平差解算。实验结果表明,系数矩阵的元素不再是单独的自变量时,使用该算法可以得到与已有非线性总体最小二乘方法相近的参数结果,从构造随机向量权阵的角度提供了一种新的解算方法。 相似文献
6.
江先华 《大地测量与地球动力学》1987,(2)
本文统一研究了引潮力位,表面点质量负荷及切向应力导致的球形层状,非旋转自引力弹性地球的变形响应,得到了随半径而变化的勒夫数,并且根据表面负荷勒夫数组成了可用于负荷潮汐改正的六种格林函数。在数值计算方面,本文较为详细地讨论了初始解向量的选取,数值积分方法以及计算结果的检核。 相似文献
7.
作者用Ｂｕｒｎｅｔｔ函数作为展开基底表示分子速度分布函数和Ｂｏｌｔｚｍａｎｎ方程，并由此证明，Ｂｏｌｔｚｍａｎｎ碰撞矩阵元的计算归结为约化积分、Ｃｌｅｂｓｃｈ－Ｇｏｒｄａｎ系数和Ｂｒｏｄｙ－Ｍｏｓｈｉｎｓｋｙ系数的计算。为了提高计算效率，作者将这些系数用超几何函数予以表示，并由此提出了高效的计算方法。 相似文献
8.
X波段双极化雷达的外场观测较少见 ,用成都市人工防雹降雨办公室 1999年 8、9两月双极化雷达的降水资料 ,对成都地区的对流云和层状云降水进行了水平剖面和垂直剖面的散射图分析 ,结果表明X波段Zh Zdr平面散射图与C波段和S波段的散射图类似 ;在 0度层上下的散射图变化清楚地反映了云中粒子的态相变化 ,这将为人工影响天气的科学作业和效果检验提供新的依据。 相似文献
9.
张国栋 《成都信息工程学院学报》1998,(4)
对由六角形冰晶粒子组成的冰云的１４种冰晶尺度分布,分别用等效球Ｍｉｅ理论和射线光学理论计算了它们在从可见光到近红外谱区的１７个波长上的散射特性参量。并利用由等效球Ｍｉｅ理论获得的散射参数及冰晶尺度分布特征参量ｒｅ（有效半径）建立了冰云光学特性的参数化公式。这些参数化公式的最大相对误差小于５％。 相似文献
10.
张国栋 《成都信息工程学院学报》1993,(3)
本文根据Mie散射理论计算了分别由7种不同谱分布构成的四种降水层状水云的单次散射反照率、不对称因子和削弱系数,给出它们的参数化公式,考虑的波长范围是0.3μm～4.7μm的太阳辐射。对光学厚度参数化公式用Stephons的列表数据进行了检验,结果表明拟合精度很高。 相似文献
11.
采用黑盘衍射模型对高能粒子与原子核弹性散射的角分布作了理论计算 ,与实验值基本相符。高能粒子弹性散射的实验结果 ,不仅可以用来确定原子核的大小 ,而且可以作为实物粒子具有波动性的又一个有力的证据。 相似文献
12.
Fracture system plays a very important role in the enrichment and accumulation of oil and gas in the reservoirs. Based on scattering wave information,Fracture Orientation Function( FOF) was built,which can be used to predict the fracture orientations. However,this method has only been verified by physical experiments without studies on the application scope. In this study,based on the linear sliding theory,FOF of the scattering wave was applied to the numerical simulation and the application scope was further studied according to fracture flexibility tensor. According to the fractures filled with gas and liquid,numerical simulation was conducted on the models with various fracture flexibilities. Numerical simulation results were used to inverse fracture orientation with the aid of the FOF of the scattering wave. The results show that it is workable to predict the vertical fracture orientation with the FOF of the scattering wave. Application of this method is more effective when the fractures are filled with gas than liquid. Moreover,the application scope can be predicted by the fracture flexibility. 相似文献
13.
简要介绍不同机构发布的Mascon模型解数据，并在全球和区域尺度上对Mascon模型解、球谐系数法以及GLDAS水文模型陆地水储量变化计算结果进行对比分析。结果表明，不同Mascon模型解具有较好的一致性；与球谐系数法反演结果相比，Mascon模型解能提高反演结果信噪比值，空间分辨率更高，保留更多有效信号，与GLDAS水文模型结果相关性更好；不同Mascon模型解中，JPL Mascon模型解信噪比值最大，与GLDAS水文模型时间序列相关性最好。 相似文献
14.
QI Jianhua LI Xianguo FENG Lijuan ZHANG Manping 《中国海洋大学学报(英文版)》2006,5(1):85-90
Total suspended particulate （TSP） samples were collected at three sites along the coast of Qingdao, China, before and during a major dust storm in March, 2002. For comparison, PM10（particulate matter with aerodynamic diameters less than 10μm） samples were collected at one of the three sites. The morphological observation and compositional analysis of bulk and individual particles were performed by using scanning electron microscopy equipped with an energy dispersive X-ray system （SEM/EDX） for the TSP and PM10 samples. The results showed that the particles of different kinds of morphology had different elemental compositions, but the particles of similar morphology did not always have the same elemental composition for non-dust samples. The morphology and composition of non-dust particles were different at different sites. The fractal and spherical particles existed mainly in the coarse fraction for non-dust samples, while in the fine mode （〈 10μm） there were floccules formed by fine particles flocking together and containing crustal elements. Compared with the non-dust particles, the dust particles were more homogeneous in terms of morphology, particle size and composition. Particles with irregular shapes and well-distributed sizes dominated in the dust samples, containing crustal elements such as Mg, A1, Si, Ca, Fe, etc. The high sulfur content indicated that homogeneous and heterogeneous reactions took place on the surfaces of the dust particles in the specific environment of Qingdao. 相似文献
15.
The generalized Born approximation is an approximation method that represents the scattering term by the error between the exact Green's function and the approximate Green's function,mainly for the gradient scattering problem.However,so far,the research on the generalized Born approximation has only stayed in theory,and its implementation techniques are rarely reported.In order to fill this gap,the basic theory of generalized Born approximation is reviewed,and the implementation method of generalized Born approximation is discussed in this paper.In particular,the problem of calculating boundary effect elimination is discussed in detail.Finally,through model trial calculation,the calculation of gradient scattering,by comparing Born approximation and finite difference method,shows that using the generalized Born approximation to calculate gradient scattering achieves higher computational accuracy. 相似文献
16.
目标信息分解就是将地物雷达电磁波回波的复杂散射过程分解为几种单一的散射过程,每种散射过程都有一个对应的散射矩阵,利用基于地物相关矩阵特征向量分解的目标分解方法,可以将目标相关矩阵分解为三种单散射体相关矩阵的加权和:单向散射,双向散射,交叉散射。将目标分解理论应用于极化成像雷达数据,可以分别得到对应于地物单向散射(奇次散射)、双向散射(偶次散射)及多向散射机制的雷达后向散射系数。本研究应用目标矩阵分解技术对青藏高原西昆仑阿克赛钦湖地区SIR-CL波段和C波段全极化多视复矩阵(MLC)数据进行处理,得到研究区地表单向散射、双向散射及多向散射后向散射系数图像。研究发现,不同性质地表具有不同电磁波散射机制,散射分解后的图像能有效去除噪声,而且能够区分具有不同散射机制的地表,对研究区多期次古湖岸线的识别有重要意义。 相似文献
17.
Based on a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model
for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical
direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the “dry-wet” method
were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation
stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included
in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport
and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from
outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion
in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two
types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution
forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the
Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of
the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with
pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water
flow, and the backward flow of pollutants released upstream is more obvious. 相似文献
18.
张钟澍 《成都信息工程学院学报》1987,(2)
本文通过对目前流行的两类关于大型稀疏矩阵优化压缩设计技巧的分析,提出一种在矩阵加、乘算法中统一使用的压缩格式。文中提出的算法,无论是矩阵的输入或者运算结果的输出均采用统一的压缩格式,所以能方便地应用于矩阵链相加或相乘的运算,而且所用的存储量较少,也大大加快了运算速度。用FORTRAN77编制的两算法的标准子程序已经在DPS7机上调试成功。 相似文献
19.
基于谱-有限元法计算一个球型、非自转、完全弹性、各向同性(SNERI)的地球固体潮形变,其中地球固体部分潮汐形变的弱解用哈密顿变分原理给出,液核部分的弱解采用静态中性分层的流体近似。计算过程中把SNERI地球进行等间距球层剖分,球面上对解函数和试探函数采用球谐展开,径向上采用线性插值。比较数值计算结果与同质地球模型的解析解结果得出,1 km径向等距剖分即可获得10~(-8)精度量级的低阶Love数。基于PREM地球模型的计算结果表明,谱-有限元法计算的固体潮2～3阶Love数与Runge-Kutta法的计算值差异在10~(-4)量级;与武汉台超导重力仪8个主潮波的实测重力潮汐因子相比,本方法计算的理论重力潮汐因子相差平均约0.15%。研究结果说明,谱-有限元法具有较好的收敛性与较高的计算精度,比传统Runge-Kutta法更适用于高精度地计算复杂地球模型的固体潮形变。 相似文献