The use of scale recursive estimation for short term quantitative precipitation forecast     

D. Bocchiola  R. Rosso 《Physics and Chemistry of the Earth》2006,31(18):1228-1239

Scale recursive estimation (SRE) is adopted for short term quantitative precipitation forecast (QPF). The precipitation field is modelled using a lognormal random cascade, well suited to properly represent the scaling properties of rainfall fields. To estimate the random cascade parameters, scale recursive maximum likelihood estimation (MLE) is carried out by the iterative expectation maximization (EM) algorithm. To illustrate the potentiality of the SRE, forecast of a synthetically generated rainfall time series is shown. Adaptive estimation of the process parameters is carried out and precipitation forecasts are issued. The forecasts from the SRE are compared with those from standard ARMA models, showing a good performance. The SRE is then adopted for forecasting of an observed half hourly precipitation series for a two day storm event in northern Italy. The SRE provides good performance and it can therefore be adopted as a tool for short term QPF.  相似文献   

Calibration framework for a Kalman filter applied to a groundwater model     

Jean-Philippe Drécourt  Henrik Madsen  Dan Rosbjerg 《Advances in water resources》2006

The paper presents a novel approach to the setup of a Kalman filter by using an automatic calibration framework for estimation of the covariance matrices. The calibration consists of two sequential steps: (1) Automatic calibration of a set of covariance parameters to optimize the performance of the system and (2) adjustment of the model and observation variance to provide an uncertainty analysis relying on the data instead of ad-hoc covariance values. The method is applied to a twin-test experiment with a groundwater model and a colored noise Kalman filter. The filter is implemented in an ensemble framework. It is demonstrated that lattice sampling is preferable to the usual Monte Carlo simulation because its ability to preserve the theoretical mean reduces the size of the ensemble needed. The resulting Kalman filter proves to be efficient in correcting dynamic error and bias over the whole domain studied. The uncertainty analysis provides a reliable estimate of the error in the neighborhood of assimilation points but the simplicity of the covariance models leads to underestimation of the errors far from assimilation points.  相似文献   

安庆铜矿地质储量管理系统的研究与开发   总被引：1，自引：0，他引：1  

刘兴权  卢岚 《地质与勘探》2006,42(4):90-93

地质储量是矿山企业赖以生存和发展的基础,对有限的地质储量能否进行有效管理直接影响矿山企业的经济效益和持续发展.近年,国际上发达采矿国家已纷纷利用数字信息技术来改造和提升其采矿业,不仅变革了传统矿业沿袭百年的生产工艺和组织管理模式,而且极大地提高了矿山企业的生产效率和安全水平.文章针对安庆铜矿的具体情况,详细讨论了建立地质储量管理系统的技术方案与路线,进行了数据库概要设计,讨论了实现系统功能的一些关键技术.  相似文献   

利用多井干扰法预算湖南省煤炭坝矿区矿井涌水量   总被引：2，自引：0，他引：2  

卿国屏唐忆晨  龚玉红 《中国煤田地质》2006,18(2):33-35,70

在阐述煤炭坝矿区水文地质条件的基础上，利用势的霍加原理建立了水文地质模型，并以此建立了相应的数学模型。在各矿井多年排水量的基础上求出各矿井相对边界作用点的引用渗透系数Ki及Kmax，根据水文地质模型设计的已知的参数，将数学模型简化为多元一次方程组。进而求解得矿井开拓延深后矿区各矿井的涌水量。  相似文献   

顾及有色噪声的光纤陀螺信号的抗差谱分析   总被引：2，自引：0，他引：2  

吴富梅  杨元喜 《测绘科学与工程》2006,26(3):50-53

在惯导系统中，对光纤陀螺仪的零位漂移一般采取滤波的方法对其进行补偿或削弱。本文针对信号中含有低频有色噪声，在Kalman滤波和小波变换消噪不理想的情况下，提出一种新的处理零位漂移的方法。首先对信号中的有色噪声进行拟合和预报，然后对信号进行抗差谱分析，以期将有用信号、有色噪声以及周期噪声分离开。利用模拟数据对该方法进行验证，发现该方法能够剔除信号中的周期噪声，并能够削弱有色噪声的影响。  相似文献   

确定实时序贯平差自适应因子取值范围的方法     

黄贤源  隋立芬 《测绘学院学报》2006,(5)

自适应序贯平差过程中,自适应因子的不同取值可以调节模型参数的先验信息和观测信息在平差过程中的利用程度,从而使未知参数的平差值接近真值。但是自适应因子取值过大或者过小都有可能使平差结果超出后验方差估计的范围,这样平差结果虽然接近真值但是却没有现实意义和实用价值。根据后验方差估计的原理,提出了利用后验方差估计确定序贯平差中自适应因子的取值范围;并给出了相应的计算步骤。通过计算实例证明该方法不仅具有实时序贯平差平衡观测值与参数先验值的功能,而且使计算结果具有实际意义。  相似文献   

A Procedure for Estimating the Variance Function of Linear Models and for Checking the Appropriateness of Estimated Variances: A Case Study of GPS Carrier-phase Observations     

W. Bischoff  B. Heck  J. Howind  A. Teusch 《Journal of Geodesy》2006,79(12):694-704

In many applications of linear model theory, homogeneous variances are assumed. In practice, however, the variances are frequently heterogeneous. Therefore, to improve the results, the unknown variances have to be estimated. The appropriateness of the estimated variances has then to be checked by a suitable statistical test procedure. Such a procedure is also useful to study models of global positioning system (GPS) carrier-phase observations. While the functional model of GPS carrier-phase observations is widely accepted, the stochastic model is still under development. As well as the neglected correlations of GPS observations, a homogenous variance function is frequently assumed. In Bischoff et al. (J Geod 78:397–404, 2005), we showed by statistical testing that the assumption of constant variances is not appropriate. In this paper, we give a procedure to estimate an individual variance function for a pair of satellites and a procedure to check the appropriateness of the estimated variances. As an example, the approach is applied to double-differenced carrier-phase GPS observations.  相似文献   

Research on performance-based seismic design criteria     

谢礼立  马玉宏 《地震学报(英文版)》2002,15(2):214-225

IntroductionAt present, the proper design and construction of buildings for earthquake-resistance is the most effective measure to mitigate the earthquake damage. In a broad sense, the earthquake resistance design should include the following seven contents:1) Determining the seismic design criteria Determining the seismic design goals3) Determining the seismic design parameters (intensity or ground motion) and their numerical values4) Determining the category of importance for buildings and …  相似文献   

方差分量的极大验后估计   总被引：4，自引：0，他引：4  

王志忠 《测绘工程》1998,7(3):19-22

由概括函数模型出发,导出了适应于所有平差模型的方差分量的极大验后估计,这种估计实际上是先验方差与样本方差的凸组合。文中还给出了一个简单的数例,说明这种方法的可行性。  相似文献   

独立观测量抗差估计效果分析     

余学祥  吕伟才 《测绘与空间地理信息》1998,(1)

本文从多余观测分量出发,通过对观测值附加粗差的方法,对抗差估计IGGI方案的抗差效果进行了分析,得出一些结论,并提出了在实际工作中有益的建议。  相似文献