A cellular automata model of surface water flow   总被引：1，自引：0，他引：1  

Jay A. Parsons  Mark A. Fonstad 《水文研究》2007,21(16):2189-2195

Previous cellular automata models of surface water flow have been constructed to reflect steady, gradually‐varied flow conditions. While these models are extremely important in showing the near‐equilibrium forms that result from the interactions of water and boundary material, highly dynamic forms and processes require models that represent unsteady flow conditions. In order to simulate unsteady flow in a cellular model of surface water flow, the conservation of mass and the Manning's equations are coupled with an algorithm to delay the movement of water from one pixel to the next until the correct timing is reached. This approach yields highly realistic flood wave hydrographs when compared with flood observations in the Walnut Gulch Experiment Watershed. Coupling this unsteady flow model with simple laws of sediment erosion, transport, and deposition should allow event‐based simulations of watershed and river channel geomorphologic change. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

GPS单点测速的误差分析及精度评价   总被引：6，自引：0，他引：6  

王甫红张小红  黄劲松 《武汉大学学报(信息科学版)》2007,32(6):515-519

首先从理论和实测数据模拟两方面分析了SA取消后各类误差源对GPS测速的影响,推导并计算了GPS单点测速可能达到的精度水平。然后用静态数据模拟动态测速试验和实测动态数据测速与同步高精度惯导测速的动态试验进行验证。结果表明,采用载波相位导出的多普勒观测值使用静态数据模拟动态测速,其精度可以达到mm/s级;用接收机输出的多普勒观测值进行测速时,其精度为cm/s级。在动态测速试验中,GPS单点测速方法（即多普勒观测值测速与导出多普勒观测值测速）间的符合精度达到cm/s级,与高精度的惯导测速结果的符合精度为dm/s级,而且和运动载体的动态条件（如加速度和加速度变化率的大小）具有很强的相关性。  相似文献   

电子经纬仪测量系统在偏置型抛物面天线检测中的应用     

李广云  黄玲 《测绘工程》1998,7(4):27-31,37

将电子经纬仪工业测量系统模拟摄影测量系统,把经纬仪水平角、垂直角观测值化算为虚拟像点坐标观测值,按摄影测量光束法平差进行二台或多台经纬仪间的系统定代间坐标解算,从而实现了经纬仪在任意姿态下的空间坐标测量功能。在光束法平差的基础上开发了中文版ＴＳＳＴ２．００工业测量系统软件。最后介绍了偏置型抛物面天线的数学模型和ＴＳＳＴ工业测量系统在其检测中的应用。  相似文献   

一次范数最小估计的无偏性   总被引：5，自引：0，他引：5  

周世健 《测绘学院学报》1998,(4)

理论上一次范数最小 ( L1 )估计的唯一性不存在 ,其唯一性主要取决于解算方法 ,大量算例验证其唯一性存在。本文作者基于算法来保证其唯一性 ,进而首次从理论上验证 L1估计的无偏性。利用初始反对称估计 ,设计了两个等价的线性规划问题 ,由此来解算得到 L1估计 ,根据误差分布为对称分布 ,便可证明 L1 估计的无偏性  相似文献   

Accounting for Estimation Optimality Criteria in Simulated Annealing   总被引：1，自引：0，他引：1  

P. Goovaerts 《Mathematical Geology》1998,30(5):511-534

This paper presents both estimation and simulation as optimization problems that differ in the optimization criteria, minimization of a local expected loss for estimation and reproduction of global statistics (semivariogram, histogram) for simulation. An intermediate approach is proposed whereby an initial random image is gradually modified using simulated annealing so as to better match both local and global constraints. The relative weights of the different constraints in the objective function allow the user to strike a balance between smoothness of the estimated map and reproduction of spatial variability by simulated maps. The procedure is illustrated using a synthetic dataset. The proposed approach is shown to enhance the influence of observations on neighboring simulated values, hence the final realizations appear to be better conditioned to the sample information. It also produces maps that are more accurate (smaller prediction error) than stochastic simulation ignoring local constraints, but not as accurate as E-type estimation. Flow simulation results show that accounting for local constraints yields, on average, smaller errors in production forecast than a smooth estimated map or a simulated map that reproduces only the histogram and semivariogram. The approach thus reduces the risk associated with the use of a single realization for forecasting and planning.  相似文献   

Modelling dispersion in complex open channel flows: Fuzzy calibration (2)     

B. G. Hankin  K. J. Beven 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(6):397-412

Part 1 of this study assessed the effectiveness of dispersion models based around random particle tracking (RPT) applied an overbank flow in the Flood Channel Facility at HR Wallingford. Several of the RPT models that were used predicted the mixing behaviour of the tracer in the complex channel flow to within an acceptable accuracy. If there is no uniqueness in the model structure which can be used to represent the true system to within the limitations of the available observations, then this implies an inherent degree of ambiguity in our knowledge of the physically based model structure. This suggests that we should be less forthright in the optimisation of each individual model structure, and perhaps investigate more of the parameter combinations for each model which yield feasible simulations of the system. An alternative fuzzy calibration technique is introduced which avoids the optimisation process and takes account of uncertainties in the model structure, parameter sets and observed data in prediction.  相似文献   

水氡仪的标定与故障分析     

张贵运  庞云峰 《山西地震》1998,(2):58-60

在多年工作的基础上,介绍了水氡仪器的标定方法,分析了水氡仪器常见故障的原因及判别、排除方法等,指出所介绍的方法可供仪器标定人员工作时参考。  相似文献   

机载成像光谱仪的外定标方法          下载免费PDF全文

张玉香  张广顺 《应用气象学报》1998,9(4):485-491

该文描述了基于反射率方法的机载中分辨率成像光谱仪（AMODIS）外定标方法。可见光和近红外波段的17个通道定标结果表明,成像光谱仪两个飞行高度测值的外定标系数是非常吻合的,其相对差为0.19%～3.89%;成像光谱仪关于草地航测的反演值与地面实测值比较,结果也是比较接近的。  相似文献   

Continuous spatially distributed simulation of surface and subsurface hydrological processes in a small semiarid catchment     

Marco Maneta  Susanne Schnabel  Victor Jetten 《水文研究》2008,22(13):2196-2214

  相似文献   

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张为民  王勇 《大地测量与地球动力学》2007,27(4):44-46

??10???????FG5-112?????????????й???????????????????о?????嶯??????????????????????68??????????ι????????????С??2??10 ^-8 ms ^-2???????????????????????С?????????????;????????????????????????????????????仯?????1??10 ^-8 ms ^-2 /a??????????λ???????-0.38 cm/a;??????????λ?仯??????????????????????????????  相似文献