Application of a neural network model in establishing a stage–discharge relationship for a tidal river     

Seree Supharatid 《水文研究》2003,17(15):3085-3099

This paper presents the applicability of neural network (NN) modelling for forecasting and filtering problems. The multilayer feedforward (MLFF) network was first constructed to forecast the tidal‐level variations at the mouth of the River Chao Phraya in Thailand. Unlike the well‐known conventional harmonic analysis, the NN model uses a set of previous data for learning and then forecasting directly the time‐series of tidal levels. It was found that lead time of 1 to 24 hourly tidal levels can be predicted successfully using only a short‐time hourly learning data. The MLFF network was further used to establish a stage–discharge relationship for the tidal river. The results show a considerably better performance of the NN model over the conventional models. In addition, the stage–discharge relationship obtained by the NN model can indicate reasonably well the important behaviour of the tidal influences. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

福建省地壳形变观测网络建设   总被引：6，自引：5，他引：1  

丁学仁  史粦华  林继华  吴绍祖  傅再扬 《大地测量与地球动力学》2003,23(3):120-124

介绍了福建省地壳形变观测网络的建设。福建省地壳形变观测网络，以GPS观测技术为主，结合精密水准、精密重力和流动地磁测量，将3者重合到GPS观测基准站上获取观测信息，初步构成一个时空相结合，点线面与长中短兼顾的高精度、高时空分辨率的地壳形变观测网络。该网络可动态监测福建省东南沿海地区地壳运动变化，为地震预测预报提供背景信息，将取得显著的社会效益和经济效益。  相似文献   

Primary proton spectrum around the knee deduced from the emulsion-chamber data obtained at Mts. Fuji and Kanbala     

J. Huang  N. Hotta  K. Kasahara  I. Ohta  S. Ozawa  T. Saito  M. Shibata  X. W. Xu  T. Yuda 《Astroparticle Physics》2003,18(6):637-648

We have done extensive Monte Carlo simulations using the new simulation codes of CORSIKA and COSMOS to compare with the gamma-family data obtained at Mts. Fuji (3750 m above sea level) and Kanbala (5500 m above sea level). Then, we estimated the primary proton and helium spectra around the knee energy region using a multiple-layered feed-forward neural network as a classifier of primary particle kind. The selection efficiency of proton-induced family events is estimated to be 82%. The flux value of protons at 2×10¹⁵ eV is (5.5±1.5)×10⁻¹⁴ (m⁻² s⁻¹ sr⁻¹ GeV⁻¹). The result suggests heavy-enriched primary composition around the knee region.  相似文献   

SOFTWARE REVIEWS     

《The Professional geographer》1988,40(1):106-116

software reviews are in this article BMDP/PC CONCEPTS COMPUTERIZED ATLAS EVALUATION OF ALTERNATE PROPOSALS (EAP) EXTRA: EXPRESS TRANSIT ANALYSIS MATC CAD MOTORS TRANSPORTATION PACKAGE PCMAP: Thematic Mapping Software for the IBM Personal Computer, Version 2.3 PLACE TRANPLAN . US-ATLAS  相似文献   

RBF神经网络的汛期旱涝预报方法研究   总被引：11，自引：8，他引：3       下载免费PDF全文

王艳姣  张鹰  邓自旺  宋德众 《热带气象学报》2005,21(1):100-106

分析广州2003年1～6月的SO2、NO2和PM10指数,发现(1)SO2、NO2和PM10具有非常好的同步变化关系,且以NO2和PM10的相关最大。(2)从月平均值来看,PM10是整个时段的主要污染物,SO2次之,NO2最小(1月除外);PM10和NO2呈现出逐月减小趋势,SO2变化平稳。主要讨论PM10指数的变化。(3)从月方差值来看,SO2、NO2和PM10的最大值均在1月,次大值在2月。(4)给出了几种地面气压型,结论显示主要清洁时段出现在锋区强风型,主要污染时段出现在脊内回流型。在脊内回流型下,若由前期的静风转吹东南(从东到南)风时,指数会增大。  相似文献   

Numerical simulations of a Mars geodesy network experiment: Effect of orbiter angular momentum desaturation on Mars' rotation estimation     

P. Rosenblatt  J.C. Marty  J.P. Barriot  V. Dehant 《Planetary and Space Science》2004,52(11):965-975

The scientific objectives of a geodetic experiment based on a network of landers, such as NEIGE (NEtlander Ionosphere and Geodesy Experiment) are to improve the current knowledge of Mars' interior and atmosphere dynamics. Such a network science experiment allows monitoring the motions of the Martian rotation axis with a precision of a few centimeters (or milli-arc-seconds (mas)) over annual and sub-annual periods. Thereto, besides radio tracking of a Mars orbiter from the Earth, radio Doppler shifts between this orbiter and several landers at the planet's surface will be performed. From the analysis of these radio Doppler data, it is possible to reconstruct the orbiter motion and Mars' orientation in space. The errors on the orbit determination (position and velocity of the orbiter) have an impact on the geodetic parameters determination from the Doppler shifts and must be removed from the signal in order to achieve a high enough accuracy. In this paper, we perform numerical simulations of the two Doppler signals involved in such an experiment to estimate the impact of the spacecraft angular momentum desaturations on the determination of Mars' orientation variations. The attitude control of the orbiter needs such desaturation maneuvers regularly repeated. They produce velocity variations that must be taken into account when determining the orbit. For our simulations, we use a priori models of the Martian rotation and introduce the spacecraft velocity variations induced by each desaturation event. By a least-squares adjustment of the simulated Doppler signals, we then estimate the orbiter velocity variations and the parameters of the Mars' rotation model. We show that these velocity variations are ill resolved when the spacecraft is not tracked, therefore requiring a near-continuous tracking from the Earth to accurately determine the orbit. In such conditions we show that only 15- of lander-orbiter tracking per week allows recovering Mars' orientation parameters with a precision of a few mas over a period of 1 Martian year.  相似文献   

一种基于网络拓扑关系的地图匹配算法   总被引：3，自引：0，他引：3  

陈波  王茂林  王宏  杨天克 《测绘科学技术学报》2006,23(5):331-334

地图匹配是车辆导航定位系统中提高定位精度的一种方法,其精度受定位数据、地图数据质量及坐标系转换关系的影响.在分析现有算法的基础上,提出了一种基于网络拓扑关系的地图匹配算法.该算法只需将GPS定位数据和GIS 数据相结合,即可用算法的形式解决地图匹配中一些常见的问题.实验证明:该算法是一种精度高、效率好、实用性强的地图匹配算法,具有较好的实用价值.  相似文献   

Derivation of Photosynthetically Available Radiation from METEOSAT data in the German Bight with Neural Nets   总被引：1，自引：0，他引：1  

Kathrin Schiller 《Ocean Dynamics》2006,56(2):79-85

Two different models, a Physical Model and a Neural Net (NN), are used for the derivation of the Photosynthetically Available Radiation (PAR) from METEOSAT data in the German Bight; advantages and disadvantages of both models are discussed. The use of a NN for derivation of PAR should be preferred to the Physical Model because by construction, a NN can take the various processes determining PAR on a surface much better into account than a non-statistical model relying on averaged relations.

Kathrin SchillerEmail:

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南京奥体中心主轴线的测设     

高俊强  许耀东 《测绘工程》2006,15(3):64-66,73

结合南京奥体中心主轴线的测设实践介绍了一种不同于常规的归化法轴线测设方法,结合测量误差理论对该方法进行了精度分析,给出了相应的精度估算式,通过工程实例的具体数据说明该方法具有较高的归化精度。  相似文献   

利用一种模糊神经网络对遥感影像进行分类的研究     

张强  周秋生 《测绘工程》2006,15(5):42-46

结合遥感影像的特点,提出一种模糊逻辑系统和神经网络中的BP算法相结合的模糊神经网络,利用其进行整个遥感图像的分类,并和典型的BP神经网络进行对比,发现其优点以及存在的问题。  相似文献