On the testing of fully integrated surface–subsurface hydrological models     

Megan L. Sebben  Adrian D. Werner  Jessica E. Liggett  Daniel Partington  Craig T. Simmons 《水文研究》2013,27(8):1276-1285

Studies employing integrated surface–subsurface hydrological models (ISSHMs) have utilized a variety of test cases to demonstrate model accuracy and consistency between codes. Here, we review the current state of ISSHM testing and evaluate the most popular ISSHM test cases by comparing the hydrodynamic processes simulated in each case to the processes found in well‐characterized, real‐world catchments and by comparing their general attributes to those of successful benchmark problems from other fields of hydrogeology. The review reveals that (1) ISSHM testing and intercode comparison have not adopted specific test cases consistently; (2) despite the wide range of ISSHM metrics available for model testing, only two model performance diagnostics are typically adopted: the catchment outflow hydrograph and the catchment water balance; (3) in intercode comparisons, model performance is usually judged by evaluating only one performance diagnostic: the catchment outflow hydrograph; and (4) ISSHM test cases evaluate a small number of hydrodynamic processes that are largely uniform across the model domain, representing a limited selection of the processes of interest in well‐characterized, real‐world catchments. ISSHM testing would benefit from more intercode comparisons using a consistent set of test cases, aimed at evaluating more catchment processes (e.g. flooding) and using a wider range of simulation diagnostics (e.g. pressure head distributions). To achieve this, a suite of test case variations is required to capture the relevant catchment processes. Finally, there is a need for additional ISSHM test problems that compare model predictions with hydrological observations from intensively monitored field sites and controlled laboratory experiments. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

全驱动船舶轨迹跟踪初始位置影响分析   总被引：1，自引：0，他引：1  

邱荷珍  王磊 《海洋工程》2015,33(4):86-93

船舶轨迹跟踪属于广义上的船舶动力定位,具体来说是船舶在规定的时间内,通过轨迹跟踪系统的控制到达原本设定的位置。以某一全驱动船舶为例,分别对预定轨迹为直线和圆进行船舶轨迹跟踪时域模拟研究,通过分析船舶时域模拟轨迹与预设轨迹的水平位置偏差与艏向角偏差研究轨迹跟踪精度,并分析船舶初始位置对轨迹跟踪的影响。研究表明,船舶初始水平位置偏离设定轨迹起点越大,船舶调整至轨迹的时间越长,但最终能回到预设轨迹上;船舶初始艏向如偏离过大,会导致船舶远离预设轨迹。在实际工程应用中,可利用动力定位将船舶定位至轨迹跟踪起点,调整船舶艏向,再开始轨迹跟踪。  相似文献   

统计假设检验方法在全极化SAR变化检测中的应用   总被引：1，自引：1，他引：0  

郝洪美  张永红  石海燕  黄金波 《遥感学报》2012,16(3):520-532

本文以全极化SAR数据为研究对象。由于全极化数据相干矩阵T3或协方差矩阵C3服从复wishart分布,所以首先在此分布的基础上利用统计假设检验方法构建似然比参数,用以表征地表地物的变化程度,然后利用基于广义高斯分布模型的EM迭代算法(GGM-EM)对变化信息进行初提取,最后充分考虑上下文信息,利用概率松弛迭代算法对初检测信息进行优化。该方法不仅全自动提取变化信息,而且经过非相干平均、初始分类、分类结果优化3次降斑去噪处理,因此检测精度较高。通过与传统对数比值法的比较,证明该方法的有效性。  相似文献   

Determining the spatial scale of variation in soil radon concentration     

M. A. Oliver  I. Badr 《Mathematical Geology》1995,27(8):893-922

Increasing concern about possible links between emissions of radon and certain types of malignant disease has led to local and regional surveys to measure radon concentrations in the soil and in dwellings. The spatial scale at which radon varies is largely unknown, and so efficient sampling schemes and methods of mapping cannot be selected. To determine the spatial scale of radon variation in the English Midlands we measured radon in the soil using solid-state nuclear track detection in three areas of different geological complexity. In two of them we used an unbalanced multistage sampling scheme with seven stages of nesting: the Hereford survey covered distances from 10 m to 7.5 km, and the Buxton survey distances from 1 m to 3.75 km. The results from the nested surveys suggested that geology exerts a strong control on the variation. Finally radon was measured every 20 m along a 2-km long transect which crossed several lithologies close to Nottingham. The soil radon values changed in an erratic way along the transect. The sample variogram of radon has a substantial nugget variance, suggesting that much of the variation occurred for distances less than the sampling interval. The structure at the longer scale seems to be controlled by the underlying geology. These results have implications for designing further surveys and for selecting a method of mapping. Stratification based on lithology might be the only feasible solution to sampling, estimating and mapping radon concentrations over large areas. Where the locally erratic component of variation is large, estimation by kriging, for example, would confer little additional benefit compared with that by classification.  相似文献   

一种高分辨率遥感影像建筑物自动检测方法     

张通  潘励 《测绘地理信息》2020,(2):101-105

高分辨率遥感影像具有丰富的空间信息、地物几何结构和纹理信息,有助于对地物目标进行认知和解译。而建筑物目标在人类活动区域内占据重要地位,对高分辨率遥感影像中的建筑物进行自动检测具有重大意义。提出了一种基于全卷积神经网络的建筑物自动检测方法,并制作了建筑物样本数据集,利用基于区域的全卷积神经网络和特征检测网络进行建筑物检测模型的参数训练,对待检测影像进行预处理之后利用模型进行建筑物检测,得到影像中的建筑物目标的具体位置和类别置信度。实验证明,提出的检测方法具有更好的效果和更快的速度。检测召回率达到92%,检测准确率达到98%,证明了该方法针对建筑物检测具有较高的精度和较强的稳定性。  相似文献   

Serpentinite textural evolution related to tectonically controlled solid-state intrusion along the Kurosegawa Belt, northwestern Kanto Mountains, central Japan     

Ken-Ichi  Hirauchi 《Island Arc》2006,15(1):156-164

Abstract   Serpentinite bodies in the Kurosegawa Belt are mapped along fault boundaries between the Cretaceous Sanchu Group (forearc basin-fill sediments) and the rocks of the Southern Chichibu Belt (Jurassic to Early Cretaceous accretionary prism) in the northwestern Kanto Mountains, central Japan. The serpentinites were divided into three types based on microtextures and combinations of serpentine minerals: massive, antigorite and chrysotile serpentinites. Massive serpentinite retains initial pseudomorphic textures without any deformation after serpentinization. Antigorite serpentinite exhibits shape-preferred orientation of antigorite replacing the original lizardite and/or chrysotile to form pseudomorphs. It has porphyroclasts of chromian spinel, and is characterized by ductile deformation under relatively high-pressure–temperature conditions. Chrysotile serpentinite shows evidence for overprinting of pre-existing serpentinite features under shallow, low-temperature conditions. It exhibits unidirectional development of chrysotile fibers. Foliations in antigorite and chrysotile serpentinites strike parallel to the elongate direction of the serpentinite bodies, suggesting a continuous deformation during solid-state intrusion along the fault zones after undergoing complete serpentinization at deeper levels (lower crust and upper mantle).  相似文献   

蠕状石成因研究的新进展   总被引：1，自引：0，他引：1  

刘春华  陈华 《世界地质》1996,15(1):7-12

重点介绍了蠕状石成因的研究现状和目前流行的几种成因假说，并对其进行了讨论和评价，尤其对“出溶硅氧泵模式”假说的蠕状石出溶的原理、过程和“硅氧泵”的实验机理、数据等、做了较为详尽的阐述。  相似文献   

基于重力场模型的平均扰动场元的严密计算方法     

彭富清  张瑞华 《测绘学报》2003,32(2):108-113

卫星重力技术的进步为建立高精度的全球重力场模型提供了可能，该技术包括卫星测高、卫星重力梯度和卫星跟踪卫星等。而在建立扰动场模型的过程中一般要采用移去—恢复技术，该技术的核心是从已知的重力数据中减去根据参考重力场模型计算的扰动场元，并在最后的成果中加入移去部分对应的扰动场元。但在移去、恢复的过程中往往利用扰动场元在格网中心点的值乘以菜平滑因子代替扰动场元在该格网上的平均值，不可避免地引入了系统误差。从勒让德微分方程和勒让德函数的定义出发，详细研究了利用重力场模型计算扰动场元在格网上的平均值的方法，该方法在利用卫星测高资料反演海域重力异常中的应用表明，重力异常的精度得到了进一步提高。  相似文献   

新型全栓接H型钢梁柱节点滞回性能研究          下载免费PDF全文

黄健  潘文  蒋文龙 《世界地震工程》2019,35(1):167-175

提出一种新型全栓接H型钢梁柱节点。为研究节点的滞回性能,采用立式加载方案对4个不同构造方式的新型和传统全栓接H型钢梁柱节点进行拟静力试验,分析各试件的节点破坏模式、P-Δ滞回曲线、M-θ骨架曲线、承载力及延性性能。结果表明:强轴新型全栓接节点与传统全栓接节点相比,滞回曲线、骨架曲线以及各项力学性能指标基本相同。弱轴新型全栓接节点与传统全栓接节点相比,具有更好的滞回性能、更高的延性和更强的承载力,其屈服承载力、极限承载力及延性分别增加了38%、35%和32%。  相似文献   

全卷积网络和条件随机场相结合的全极化SAR土地覆盖分类     

赵泉华  谢凯浪  王光辉  李玉 《测绘学报》2020,49(1):65-78

针对经典全卷积网络(fully convolution network,FCN)分类精度低、效果差,以及传统的极化合成孔径雷达(PolSAR)土地覆盖分类方法未充分考虑地物散射特性的问题,提出了一种结合改进FCN和条件随机场(conditional random field,CRF)的全极化SAR土地覆盖分类算法。首先,利用Freeman分解和Pauli分解建模全极化SAR影像,同时提取各分解对应的散射特征,参考Freeman分解散射功率获取其主散射分量对应的主散射地物;同时,借鉴在图像分类领域中具有卓越表现的FCN-Vgg19-8s网络,考虑其高层卷积参数量大和低层卷积模型参数优化程度不足,通过在高层和中层分别构建多尺度卷积组和代价函数设计了FCN-MD-8s网络,保证对整体模型参数进行降维和优化;以Freeman分解散射机理特征为基准,采用级连式迁移学习结构,实现FCN-MD-8s网络的模型训练和测试;然后,根据主散射分量所对应的主散射地物,在各分量预测图中提取出主特征地物,得到分量地物分类结果,并将其进行叠加得到全局粗分类;最后,利用全连接CRF结合Pauli相干分解重建假彩色图,对全局粗分类进行全局像素类别转移获得细分类结果。通过对分类结果定性和定量分析,可知提出算法具有有效性和可行性。  相似文献