CINRAD/SA雷达数字中频改造技术难题及解决方法     

杨传凤  柴秀梅  张海燕  黄秀韶  涂爱琴  刘朝晖  袁希强 《气象科技》2012,40(1):5-8

2008年以来,济南CINRAD/SA雷达由于模拟中频接收机系统性能参数退化导致雷达运行的可靠性和稳定性较差,且故障率较高。为了更好的保障雷达服务于气象,2009年7月济南完成数字化中频升级改造工程,改造后的数字中频雷达相位噪声非常稳定,速度信息量更加可信和精确。扼要介绍了数字中频接收机的工作原理,主要是对数字中频安装调试及改造过程中遇到的软、硬件问题的解决措施和改造后的技术参数测试进行技术性的总结,旨在对同行今后的工作具有参考借鉴价值。  相似文献   

基于多方位DEM地形晕渲的黄土地貌正负地形提取   总被引：5，自引：0，他引：5  

陈永刚  汤国安  周毅  李发源  宴实江  张磊 《地理科学》2012,(1):105-109

以陕北绥德县韭园沟流域5 m分辨率DEM数据为基础,在数字地形分析、多元统计和数据挖掘方法的基础上,提出利用多方位DEM地形晕渲、坡度等多元指标,以主成分分析消除多重共线性和约减维数,并以Logis-tic回归模型提取黄土高原正、负地形的方法。研究结果表明:模型提取精度为82.1%,Kappa统计量为0.629;模型在6个不同流域测试样本上正、负地形的平均精度分别为77.6%,84.9%,加权平均精度为81.3%,模型具有较好的一致性和泛化能力,正、负地形提取效果良好。  相似文献   

基于C#与Fortran混合编程技术实现法方程系数阵求逆     

尚金光  张献州  张勇  官超伟 《东北测绘》2012,(3):137-139

开发控制网平差软件时,需要进行界面、算法优化设计等等。开发人员往往喜欢用图形化编程语言,但图形化编程语言在科学计算方面往往不够突出。测量平差需要进行很多的矩阵运算,如法方程系数阵的求逆计算等。Fortran语言是目前流行较广的适用于科学计算的程序开发语言,但是它的图形界面开发功能较弱。C#是新一代面向对象开发语言,擅长于图形界面系统开发。本文采用C#与Fortran混合开发,发挥两者的优点,实现法方程系数阵的快速求逆。  相似文献   

矩阵方程A^TXA=D扰动分析          下载免费PDF全文

杨兴东  周月军  何青泉  邵保刚 《大气科学学报》2008,31(3):447-451

利用矩阵分块与矩阵范数的性质,研究矩阵方程A^TXA=D,获得该方程的扰动界,这些结果可用于模型修正中的数值计算。  相似文献   

地气图预测全国月降水的实践总结   总被引：9，自引：6，他引：3  

汤懋苍  成青燕  张东方  郭俊琴  郭维栋 《高原气象》2008,27(5)

根据地热涡的移动规律和地热释放的持续性,我们设计了两种月降水的预测方法:(1)外推法,依据过去2~3个月地热涡和多雨区的移向、移速,外推下个月多雨区的位置;(2)"正多负少"规则,利用地热释放的持续性,对3.2 m地温月际变温为正的地区,预测下月多雨,月际变温为负的地区预测下月少雨("正多负少"规则)。此规则的历史拟合率约为65%。指出了5种不符合"正多负少"规则的情形及其可能原因。利用上述2种方法,从2005年9月开始进行全国降水预测试验,按全国统一评分方法,2年多来平均得分为67.5分,2007年12个月的平均得到70.5分。  相似文献   

一类奇异半线性椭圆型方程Dirichlet问题     

霍晓音  李刚 《南京气象学院学报》2008,31(1):135-138

应用奇异非线性Dirichlet问题的上下解方法以及极大值原理,得到了一类奇异半线性Dirichlet问题正古典解的存在性,最后进一步给出解的正则性。  相似文献   

Influence of Water Pressure on the Stress State in Stopes with Cohesionless Backfill   总被引：2，自引：2，他引：0  

Li Li  Michel Aubertin 《Geotechnical and Geological Engineering》2009,27(1):1-11

The rapid increase of backfill use in underground mines requires a better understanding of the interaction between the fill material and the surrounding rock mass. This is a fairly complex issue as backfill materials are weak compared to the rock mass. This difference in the mechanical behavior induces a stress transfer along the contact area. Previous work conducted on backfilled trenches and mining stopes has shown that basic arching theory can be used to estimate earth pressures in narrow, vertical openings. In this regard, most existing solutions have been developed for dry backfills. However, in many cases, water is present in mine stopes, so its effect should be assessed. In this paper, the authors present a solution to evaluate the stress state in submerged or partially submerged backfilled stopes. The proposed analytical solution is validated against numerical modeling results.  相似文献   

LRS Bianchi-V cosmology with decaying vacuum density and heat flow     

C. P. Singh 《Astrophysics and Space Science》2009,323(2):197-203

In this paper we consider a locally-rotationally-symmetric (LRS) Bianchi type-V perfect fluid model with variable cosmological ‘constant’ representing the energy density of vacuum. The field equations are solved with and without heat conduction by using a variation law for the mean Hubble parameter, which is related to the average scale factor of the metric and yields a constant value of the deceleration parameter. A constant value of deceleration parameter generates power-law form of average scale factor which is used to find the exact solutions with and without heat conduction with decaying vacuum density. The solutions presented here satisfy all the necessary conditions for the physically acceptability. The thermodynamical relations in decaying vacuum fluid model are also studied in detail.  相似文献   

A generalization of extendedQ-mode factor analysis to data matrices with variable row sums     

J. E. Klovan 《Mathematical Geology》1981,13(3):217-224

The extended method of Q-mode factor analysis developed by Miesch for data matrices with constant row sums is generalized to data matrices with variable row sums. With the algorithm provided it is possible to compute factor scores in the metric of the original data and compute goodness-of-fit statistics and model geological systems unconstrained by constancy of row sums of data points.  相似文献   

Solutions of pore pressure build up due to progressive waves     

L. Cheng  B. M. Sumer  J. Fredse 《国际地质力学数值与分析法杂志》2001,25(9):885-907

The analytical solution of soil pore pressure accumulations due to a progressive wave is examined in detail. First of all, the errors contained in a published analytical solution for wave‐induced pore pressure accumulation are addressed, and the correct solution is presented in a more general form. The behaviour of the solution under different soil conditions is then investigated. It is found that the solution for deep soil conditions is sensitive to the soil shear stress in the top thin layer of the soil. However the solution is significantly influenced by the shear stress in the thin layer of soil near the impermeable base, for shallow and finite depth soil conditions. It is also found that a small error in the soil shear stress can lead to a large error in the accumulated pore pressure. An error analysis reveals the relationships between the accuracy of the pore pressure accumulation and the accuracy of the soil shear stress. A numerical solution to the simplified Biot consolidation equation is also developed. It is shown that the error analysis is of significant value for the numerical modelling of pore pressure buildup in marine soils. Both analytical and numerical examples are given to validate the error estimation method proposed in the present paper. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献