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Yang Y.-W.,Wuhan Geomatic Institute | Yang Y.-W.,Wuhan Geotechnical Engineering and Surveying Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The displacement evaluation method for composite soil-nailing walls has not been discovered due to the complicated properties of soils and various retaining structures although composite walls have been widely applied. 26 typical case histories of composite soil-nailing walls in deep excavations are presented. The maximum lateral displacements and settlements are analyzed in these cases to find out the relationships between geology and retaining structures. The statistical results show that the maximum lateral displacements and settlements for composite soil-nailing walls are 0.4% and 0.2% of excavation depths, respectively. The former is about twice that for piles and diaphragms. The maximum lateral displacements are reduced slightly for the composite soil-nailing walls with prestressed anchors and micro-piles. The new concept, the unit shear strength of soil, is proposed based on the Mohr-Coulomb failure criterion to quantify the whole shear strength of soil. The maximum displacements are found to decrease significantly as the unit shear strength for the main strata increases. Source

Fan S.-K.,Wuhan Huatai Geotechnical Engineering Company | Yang Y.-W.,Wuhan Geotechnical Engineering and Surveying Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The various strategies and schemes of groundwater control are proposed and recommended for various strata and types of groundwater encountered in deep foundation pits located in 1st terrace near Yangtze River in Wuhan City based on the engineering experience in recent fifteen years. For the confined water in this terrace, the deep well is believed to be the most effective method. Source

Wang Z.,Wuhan University | An J.,Wuhan University | Sun W.,Wuhan University | Sun W.,Wuhan Geotechnical Engineering and Surveying Institute | Zhao Y.,Wuhan University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2011

A total solar eclipse on 22 July 2009, the longest one of this century, occurred in East Asia and Pacific. Meanwhile, a medium magnetic storm arise in the late eclipse. The electron density profiles in maximum eclipse time were obtained from COSMIC radio occultation, and time series of TEC in local area was obtained from ground GPS stations of Wuhan CORS. And some physical mechanism of ionospheric effects during in the eclipse were analyzed. Source

Wan Y.,Wuhan University | Wang D.,Wuhan University | Wang D.,University of Maryland University College | Xiao J.,Wuhan Geotechnical Engineering and Surveying Institute | And 2 more authors.
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2013

Image mosaicking is defined as the registration of two or more images that are then combined into a single image. One of the most difficult steps in the automatic mosaicking of orthoimages is deciding where to place seamlines in overlapping regions. Based on millions of image pixels, existing seamline detection methods mainly focus on how to avoid crossing buildings that are higher than the ground, which results in parallax on the overlapping images. However, various data in vector format, such as vector roads plotted manually and precisely, have not been used to aid the selection of seamlines. This paper presents a novel approach using vector roads alone to generate seamlines, and describes its application to the automatic generation of seamlines for image mosaicking of the city of Wuhan, China. A representative seamline is extracted as follows. First, the skeleton of the overlapping region of adjacent images is extracted after the delineation of boundaries of individual images. Second, vector roads in the overlapping region are overlaid with the extracted skeleton to build a weighted graph G (V, E). Finally, the Floyd-Warshall algorithm is applied to find the lowest cost path from I to O, which refer to two intersections of adjacent image polygons, with the lowest-cost path being the seamline. This vector-based approach is typically more efficient than raster-based approaches. Experiments demonstrate the merits of the proposed approach especially when vector road networks are available. © 2012 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Source

Song Y.,Wuhan University | Jia X.-X.,Wuhan Geotechnical Engineering and Surveying Institute
2010 2nd Conference on Environmental Science and Information Application Technology, ESIAT 2010 | Year: 2010

Remote sensing change detection is a hot issue in recent years. However, most methods originate from statistical pattern recognition. Parameter resolution and time-consuming are main disadvantages of these methods. Hence, in this paper we propose a novel remote sensing change detection method which originates from neural network pattern recognition. The method is based on Growing Hierarchical Self Organization Map(GHSOM). GHSOM has flexible network architecture to adjust remote sensing scene complexity. Theoretically speaking , GHSOM is able to extract change areas well. In experiment, we select three pairs of remote sensing image. We compare the results with Gaussian Mixture Model result and traditional SOFM result. The experiment shows the proposed method is advantageous in efficiency and detection accuracy. It can be expected that the method will be applied in GIS data updating, land use cover surveying, and natural disaster evaluation. ©2010 IEEE. Source

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