Propagation of uncertainties in interpolated rainfields to runoff errors     

Yeboah Gyasi-Agyei 《水文科学杂志》2019,64(5):587-606

Conditional daily rainfields were generated using collocated raingauge radar data by a kriging interpolation method, and disaggregated into hourly rainfields using variants of the method of fragments. A geographic information system (GIS)-based distributed rainfall–runoff model was used to convert the hourly rainfields into hydrographs. Using the complete radar rainfall as input, the rainfall–runoff model was calibrated based on storm events taken from nested catchments. Performance statistics were estimated by comparing the observed and the complete radar rainfall simulated hydrographs. Degradation in the hydrograph performance statistics by the simulated hourly rainfields was used to identify runoff error propagation. Uncertainty in daily rainfall amounts alone caused higher errors in runoff (depth, peak, and time to peak) than those caused by uncertainties in the hourly proportions alone. However, the degradation, which reduced with runoff depth, caused by the combined uncertainties was not significantly different from that caused by the uncertainty of amounts alone.  相似文献   

灰色误差理论在岩矿测试数据处理中的应用   总被引：1，自引：2，他引：1  

陈月源  曹成东  袁秀茹  魏轶  谈建安 《岩矿测试》2009,28(6):576-582

介绍了灰色误差理论,并应用于岩矿测试数据基本处理。结果表明,在误差变化范围小的岩矿化学分析中,测量数据的累加曲线为线性关系,在元素不均匀性分布的岩矿化学分析(例如不均匀性金的测试)和岩石强度试验等分散性大的测试中,测量数据的累加曲线为曲线关系,但灰色标准偏差和传统统计学的标准偏差非常接近。该方法简单易行,具有相当的精度和较强的实用性,对测量数据少或难于寻求统计规律的测量过程尤为实用,是一种新的尝试。  相似文献   

Storm surge simulation along the Meghna estuarine area: an alternative approach   总被引：1，自引：1，他引：0  

PAUL Gour Chandr  SENTHILKUMAR Sukumar  PRIA Rana 《海洋学报(英文版)》2018,37(1):40-49

In this study, numerical prediction of surges associated with a storm was made through the method of lines (MOL) in coordination with the newly proposed RKARMS (4, 4) method for the meghna estuarine region, along the coast of Bangladesh. For this purpose, the vertically integrated shallow water equations (SWEs) in Cartesian coordinates were firstly transformed into ordinary differential equations (ODEs) of initial valued, which were then soloved using the new RKARMS (4, 4) method. Nested grid technique was employed for resolving the complexities of the region of interest with minimum cost. Fresh water discharge through the lower Meghna River was taken into account along the north east corner of the innermost child scheme. Numerical experiments were performed with the severe cyclone on April 1991 that crossed the coast over the study area. Simulated results by the study were found to be in good agreement with some reported data and were found to compare well with the results obtained by the MOL in addition with the classical 4th order Runge-Kutta (RK (4, 4)) method and the standard finite difference method (FDM).  相似文献   

A Track Initiation Method for the Underwater Target Tracking Environment     

LI Dong-dong  LIN Yang  ZHANG Yao 《海洋工程》2018,32(2):206-215

A novel efficient track initiation method is proposed for the harsh underwater target tracking environment (heavy clutter and large measurement errors): track splitting, evaluating, pruning and merging method (TSEPM). Track initiation demands that the method should determine the existence and initial state of a target quickly and correctly. Heavy clutter and large measurement errors certainly pose additional difficulties and challenges, which deteriorate and complicate the track initiation in the harsh underwater target tracking environment. There are three primary shortcomings for the current track initiation methods to initialize a target: (a) they cannot eliminate the turbulences of clutter effectively; (b) there may be a high false alarm probability and low detection probability of a track; (c) they cannot estimate the initial state for a new confirmed track correctly. Based on the multiple hypotheses tracking principle and modified logic-based track initiation method, in order to increase the detection probability of a track, track splitting creates a large number of tracks which include the true track originated from the target. And in order to decrease the false alarm probability, based on the evaluation mechanism, track pruning and track merging are proposed to reduce the false tracks. TSEPM method can deal with the track initiation problems derived from heavy clutter and large measurement errors, determine the target’s existence and estimate its initial state with the least squares method. What''s more, our method is fully automatic and does not require any kind manual input for initializing and tuning any parameter. Simulation results indicate that our new method improves significantly the performance of the track initiation in the harsh underwater target tracking environment.  相似文献   

考虑多因素衰减的陆域大容量气枪震源子波模拟及其影响要素分析     

张国平  王辉山  王青平  林岩钊  张树君  金星 《大地测量与地球动力学》2019,39(12):1243-1248

建立针对大容量气枪震源的气泡振荡方程及压力子波方程，引入多个对模拟结果具有重要影响的修正因子，包括基于开口的热力学模型、枪口节流作用、蒸发冷凝、枪体影响、气体释放率等来改善传统的单枪压力子波计算方法。利用模型及与水库实测的子波比对结果，分析各修正因素对子波模拟的影响，通过改进的单枪信号进一步计算大容量枪阵的压力子波。对比改进的模拟方法预测的子波波形与实测信号，结果显示，改进的模型比原有模型能更好地模拟单枪和枪阵的震源子波。最后，分析了模型产生模拟误差的原因。  相似文献   

多波束声呐图像条带中央和边缘残差处理方法     

朱正任  樊妙  邢喆  冯成凯  孙毅  阳凡林 《海洋技术学报》2019,38(5)

多波束声呐图像是进行海底底质分类的主要数据源之一,由于受海洋噪声、声波散射和混响、仪器设备等因素影响,其经各项常规改正后仍存在明显残差,突出表现在中央波束区和条带重叠区,难以形成高质量的声呐图像。文中分析了多波束声呐图像残差的成因及影响,提出了一种基于多条带最小二乘拟合的多波束声呐图像残差处理方法。首先,得到相邻声脉冲(ping)信号中央区域、重叠区域以及整体趋势的拟合函数;然后,通过拟合函数计算得到中央和重叠区域的残差改正系数;最后,通过改正系数进行残差改正。实验分析表明,该方法在保留原始细节的基础上,有效削弱了残差对声呐图像的影响,对多波束声呐图像处理具有参考和应用价值。  相似文献   

MEMS陀螺仪随机误差KF补偿方法的普适性验证     

孙伟  宋如意  王宇航  吴增林 《大地测量与地球动力学》2019,39(11):1188-1193

针对MEMS陀螺仪随机误差成为影响系统导航精度的主要因素及建模存在的普适性等问题，提出一种3次卡尔曼迭代估计的误差补偿方法。采用Allan方差对MEMS陀螺仪随机误差参数进行辨识，同时结合MEMS陀螺仪输出数据自相关与偏相关函数具备的拖尾性，设计基于时间序列ARMA的MEMS陀螺仪误差卡尔曼滤波模型。采用同型号6只MEMS陀螺仪惯性测量单元搭建测试环境，并开展导航验证实验，结果表明，经过滤波处理后的MEMS陀螺仪各项误差系数明显降低，且滤波效果随滤波次数的增加而增强。6组MEMS陀螺仪测试设备显现出的误差减弱趋势具有一致性，姿态误差对比结果也进一步验证了该方法的可行性。  相似文献   

Systematic Geometric Image Measurement Errors of Circular Object Targets: Mathematical Formulation and Correction   总被引：2，自引：0，他引：2  

S. J. Ahn  H. J. Warnecke  & R. Kotowski 《The Photogrammetric Record》1999,16(93):485-502

The use of circular object targets is very common in spatial photogrammetric object reconstruction. An object circle is projected on to the image plane as an ellipse if the object plane and the image plane are not parallel to each other. The image co-ordinates of the centre of the ellipse are usually determined automatically by means of digital image processing. These co-ordinates are then used as observations for a subsequent reconstruction of the three dimensional object point. The image co-ordinates of the centre of the ellipse and the true co-ordinates of the projected centre of the circular object target are not identical; thus eccentricity is caused, resulting in systematic geometric image measurement errors. This paper describes the functional context of this eccentricity for a typical target/camera set-up. The possible solutions for a correction of this systematic eccentricity error are derived. Guidelines for the correct combination of object target sizes and exposure distances, guaranteeing reliable image point measurements and accurate object point determination, are proposed.  相似文献   

Anomalously deep earthquakes in northwestern Italy     

Marco Cattaneo  Paolo Augliera  Stefano Parolai  Daniele Spallarossa 《Journal of Seismology》1999,3(4):421-435

It is usually assumed that earthquakes in intraplate regions occur in the upper crust, and northwestern Italy is generally assigned to this kind of normal seismicity. In this work, the depth distribution of the events localized in this area by the Istituto Geofisico Geodetico (IGG) seismic network in the period 1991–1997 is analyzed in detail. In particular, the location capability of the network is discussed, adopting as reference quarry blasts (for the epicentral position) and the locations obtained from a dense temporary network (for the depth estimate). Within the so-obtained error limits, the depth distribution of events show a characteristic pattern: while for most of the area covered by the network the well-located seismicity lies within the first 20 km of depth, in a band following the inner arc of the Western Alps, numerous events have anomalously large focal depths, reaching a maximum of 114 km. These depth determinations cannot be attributed to instabilities of the location procedure: different choices of the propagation models used for the hypocentral determination led to very similar depth values, always significantly larger than the standard values for the surrounding areas. A strong correlation has been found between the 3-dimensional distribution of these foci and the P-wave propagation anomalies obtained from tomographic studies, suggesting a direct link between elastic and rheological properties of lower crust and upper mantle in this area.  相似文献   

卡尔曼滤波模型误差的识别   总被引：3，自引：1，他引：2  

陶本藻 《大地测量与地球动力学》1999,19(4):15-20

本文在简述卡尔曼滤波模型基础上讨论了模型误差的检验和估计问题,提出了检验卡尔曼滤波模型误差显著性的几种统计假设检验方法,探讨并给出了估计模型误差的方法和公式。  相似文献