长春西部串湖含水介质弥散试验及污染质运移研究   总被引：2，自引：0，他引：2  

赵雪琼  卞建民  杨坡  盛骅寅 《地下水》2008,30(5):12-14

水动力弥散系数是建立地下水水质模型,进行地下水溶质运移研究的重要参数。在野外调查的基础上,设计并开展了室内二维水动力弥散试验,应用直线图解法确定了研究区含水介质的纵向、横向弥散系数。建立了该区地下水溶质运移模型,并对其进行了预测分析。  相似文献   

GPS高程曲面拟合算法的精度分析     

南亲江  卜建阳 《现代测绘》2008,31(4)

在GPS高程测量中需要将大地高转换为正常高。本文对GPS高程的多项式曲面拟合、多面函数拟合和移动曲面函数拟合算法进行了比较分析。结果表明,三种拟合算法均能达到四等几何水准的要求,但移动曲面拟合算法精度最高,多面函数拟合算法精度最低。  相似文献   

A general solution for tide‐induced groundwater fluctuation in an estuarine‐coastal confined and unconfined aquifer system          下载免费PDF全文

Hsi‐Ting Fang  Yih‐Chi Tan  Mo‐Hsiung Chuang  Kai‐Yuan Ke  Po‐Chia Chen 《水文研究》2018,32(14):2239-2253

This paper presents an analytical solution to tide‐induced head fluctuations in a two‐dimensional estuarine‐coastal aquifer system that consists of an unconfined aquifer and a heterogeneous confined aquifer extending under a tidal river with a semipermeable layer between them. This study considers the joint effects of tidal‐river leakage, inland leakage, dimensionless transmissivity between the tidal‐river and inland confined aquifer, and transmissivity anisotropic ratios. The analytical solution for this model is obtained via the separation of variables method. Three existing solutions related to head fluctuation in one‐ or two‐dimensional leaky confined aquifers are considered as special cases in the present solution. This study shows that there is a threshold of tidal‐river confined aquifer length. When the tidal‐river length is greater than the threshold length, the inland head fluctuations remain sensitive to the leakage effect but become insensitive to the tidal‐river width and dimensionless transmissivity. Considering leakage and transmissivity anisotropy, this study also demonstrates that at a location farther from the river–inland boundary, head fluctuations increase with increasing leakage and transmissivity anisotropy; the maximum head fluctuation occurs when leakage and transmissivity anisotropy are both at their maximum values. The combined action of the 3 effects of loading, tidal‐river aquifer leakage, and inland aquifer leakage differs significantly according to various aquifer parameters. The analytical solution in this paper can be applied to demonstrate the behaviours of the head fluctuations of an estuarine‐coastal aquifer system, and the head fluctuations can be clearly described when the tidal and hydrogeological parameters are derived from field measurement data or hypothetical cases.  相似文献   

Mobile Communications,Social Networks,and Urban Travel: Hypertext as a New Metaphor for Conceptualizing Spatial Interaction*     

Mei‐Po Kwan 《The Professional geographer》2007,59(4):434-446

The widespread use of mobile communications is leading to new practices in family life and social life, and these changes have significant implications for the study of urban travel. Because of the adoption of new modes of space‐time coordination, changing time use and increasing mobility, changing use of existing urban nodes, the blurring of boundaries between home and work, the importance of social networks and social capital, and the shift to person‐to‐person connectivity, the spatial structure and processes of interaction among individuals have become much more complicated in this age of mobile communications. Static spatial frameworks based on fixed points (e.g., home or workplace) and distances among them are no longer adequate for understanding urban travel. The study of urban travel now needs new conceptualizations and new methodologies.  相似文献   

北太平洋副热带逆流区中尺度涡旋的统计特征及其分布规律   总被引：1，自引：0，他引：1  

汤博  侯一筠  殷玉齐  胡珀 《海洋与湖沼》2019,50(5):937-947

本文基于卫星高度计得到的全球非线性中尺度涡旋数据集,分析了北太平洋副热带逆流(Subtropical Countercurrent.STCC)区域中尺度涡旋的统计特征,包括其基本特征、空间分布、传播特征、季节和年际变化;给出了该区域涡旋振幅、半径、旋转速度和罗斯贝数的分布直方图,并利用瑞利分布和对数正态分布对其进行了拟合。结果显示,涡旋振幅、半径、旋转速度和罗斯贝数的直方图很好地服从于对数正态分布。此外,通过与北太平洋中涡旋的对比研究,我们发现在STCC区中对数正态分布的拟合效果更好。本研究提高了对STCC区域中尺度涡旋统计特征的认识,明确了其与大洋中涡旋的区别;通过对数正态分布对涡旋特征的拟合,清晰地体现出了其分布规律,这在很大程度上降低了对观测数据的依赖,从而帮助我们更加有效地判断和预测涡旋特征的变化,同时为数值模式中涡旋的参数化提供了依据。  相似文献   

A general solution for groundwater flow in an estuarine's leaky aquifer system after considering aquifer anisotropy          下载免费PDF全文

Po‐Chia Chen  Mo‐Hsiung Chuang  Yih‐Chi Tan  Kuo‐Chen Ma 《水文研究》2016,30(12):1862-1871

This paper presents an analytical model for describing the tidal effects in a two‐dimensional leaky confined aquifer system in an estuarine delta where ocean and river meet. This system has an unconfined aquifer on top and a confined aquifer on the bottom with an aquitard in between the two. The unconfined and confined aquifers interact with each other through leakage. It was assumed that the aquitard storage was negligible and that the leakage was linearly proportional to the head difference between the unconfined and confined aquifers. This model's solution was based on the separation of variables method. Two existing solutions that deal with the head fluctuation in one‐dimensional or two‐dimensional leaky confined aquifers are shown as special cases in the present solution. Based on this new solution, the dynamic effect of the water table's fluctuations can be clearly explored, as well as the influence of leakage on the behaviour of fluctuations in groundwater levels in the leaky aquifer system. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

基于多粒度时空对象数据模型的城市基础设施建模与管理     

杨飞  华一新  李响  李坡  杨振凯  曹一冰 《地球信息科学学报》2021,23(11):1984-1997

城市基础设施的全方位描述与信息化管理是建设新型智慧城市的重要基础。目前在城市基础设施建模与管理方面,以地图为模板的空间数据模型、传统的面向对象空间数据模型以及实时GIS数据模型不支持对时空对象组成结构、行为能力等要素的描述,无法全面、精细地表达设施对象信息,而计算机、物联网和地理信息系统（Geographic Information System,GIS）领域已有的城市基础设施管理方案忽略了对设施自身信息的管理,无法较好地支持设施对象及其产生数据的一体化管理。针对上述问题,首先通过扩展GBT30428.2-2013标准,完成了城市基础设施的分类与编码;然后基于多粒度时空对象数据模型（Multi-granularity Spatiotemporal Object Data Model, MGSTODM）,提出了一种城市基础设施对象化描述模型,支持对城市基础设施信息的全方位描述与表达;在此基础上,提出一种城市基础设施对象化管理方法,设计了相应的技术架构,并研制了基于云存储的百万级城市基础设施对象化管理原型系统。试验结果表明,所提出的城市基础设施对象化描述模型与管理方法具备可行性、有效性和高效性。  相似文献   

GPS测站坐标非线性变化研究方法的比较与分析     

田亮  孙付平  陈坡  崔建勇 《测绘工程》2011,20(2):27-30

以GPS测站残差时间序列为研究对象,采用自回归滑动平均模型（ARMA）的两种建模方法（Box-Jenkins方法和Pandit-Wu方法）和三角函数法对其进行建模拟合与分析比较。通过实验发现Pandit-Wu方法拟合效果最好,Box-Jenkins方法次之,三角函数法最差,但是通过不同的测站残差数据实验比较也发现三角函数法能更加直观地体现出非线性变化的规律,有利于进一步分析非线性变化规律的性质与机制,因此,同样具有深入研究的价值。  相似文献   

Full-Wave Seismic Data Assimilation: Theoretical Background and Recent Advances   总被引：2，自引：0，他引：2  

Po Chen 《Pure and Applied Geophysics》2011,168(10):1527-1552

The seismological inverse problem has much in common with the data assimilation problem found in meteorology and oceanography. Using the data assimilation methodology, I will formulate the seismological inverse problem for estimating seismic source and Earth structure parameters in the form of weak-constraint generalized inverse, in which the seismic wave equation and the associated initial and boundary conditions are allowed to contain errors. The resulting Euler?CLagrange equations are closely related to the adjoint method and the scattering-integral method, which have been successfully applied in full-3D, full-wave seismic tomography and earthquake source parameter inversions. I will review some recent applications of the full-wave methodology in seismic tomography and seismic source parameter inversions and discuss some challenging issues related to the computational implementation and the effective exploitation of seismic waveform data.  相似文献   

Tectonostratigraphic evolution of the Morichito piggyback basin, Eastern Venezuelan Basin     

Migdalys SalazarLorena Moscardelli  William FisherMaria Antonieta Lorente 《Marine and Petroleum Geology》2011,28(1):109-125

The Morichito piggyback basin (MPB) is a SW-NE-oriented depocenter in the Eastern Venezuelan Foreland Basin (EVFB). This piggyback basin formed by overlying the Pirital thrust during the middle to late Miocene as a result of oblique collision between the Caribbean and South-American Plates. The MPB covers an area encompassing approximately 1000 km² between the Serrania del Interior range and the Pirital high, which is a hanging wall uplift along the Pirital thrust that acts as a confining barrier on the southern boundary of the MPB. Previous studies have tried to address the tectonostratigraphic significance of the MPB, but new biostratigraphic information and recently acquired 3D seismic data have allowed us to expand the understanding of this basin. The MPB occupies a relatively small area of the EVFB; however, the MPB contains a valuable stratigraphic record that can be used to unveil the timing of the main deformational events that took place in the EVFB.This work presents the tectonostratigraphic evolution of the MPB by defining four tectonostratigraphic sequences (T1-T4). Each sequence was defined on the basis of integration of well logs, biostratigraphy, and seismic geomorphological interpretations. T1 (24-16 Ma) (late Oligocene to middle Miocene), which was deposited in shallow-marine environments, extends to the south of the Pirital high beyond the boundaries of the MPB. T1 is equivalent to the early foredeep stage of the EVFB, having been formed when structural deformation and uplifting were already occurring to the north on the proto-Serrania del Interior range (∼24-16 Ma) and the Pirital thrust was active (∼22 Ma). T2 (16-11 Ma) (middle to late Miocene) is composed of alluvial-fan deposits derived from the proto-Serrania del Interior range. The geometry and internal configuration of T2 indicate that during this time the basin was transitioning from an open-foreland basin to a confined piggyback basin. During deposition of T2, the Pirital fault was active as an out-of-sequence thrusting event (16-∼11 ma). T3 (late Miocene) and T4 (early Pliocene to Recent), composed of shallow-marine and fluvial deposits, were deposited in an already restricted piggyback basin. The Pirital high was already in place during deposition of T3 (∼11-9.3 ma). T3 and T4 represent the final phases of MPB infilling, when tectonic activity and subsidence were at their lowest rates. MPB sedimentary infilling dates the activity of thrusting events in the proto-Serrania del Interior (∼24-16 Ma), timing of maximum deformation associated with the Pirital out-of-sequence thrusting event (16-∼11 Ma), timing of final emplacement of the Pirital high (∼11-9.3 Ma), and the beginning of tectonic quiescence (<5.2 Ma).  相似文献