Cryohydrology in Canada: A brief history     

Ming‐ko Woo 《水文研究》2019,33(26):3407-3411

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Erratum to: Relationships between intensity of the Kuroshio current in the East China Sea and the East Asian winter monsoon     

Ming Yin  Xin Li  Ziniu Xiao  Chongyin Li 《海洋学报(英文版)》2018,37(9):119-119

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Modelling the time‐dependent behaviour of granular material with hypoplasticity          下载免费PDF全文

Shun Wang  Wei Wu  Zhen‐Yu Yin  Chong Peng  Xuzhen He 《国际地质力学数值与分析法杂志》2018,42(12):1331-1345

This paper presents a constitutive model for time‐dependent behaviour of granular material. The model consists of 2 parts representing the inviscid and viscous behaviour of granular materials. The inviscid part is a rate‐independent hypoplastic constitutive model. The viscous part is represented by a rheological model, which contains a high‐order term denoting the strain acceleration. The proposed model is validated by simulating some element tests on granular soils. Our model is able to model not only the non‐isotach behaviour but also the 3 creep stages, namely, primary, secondary, and tertiary creep, in a unified way.  相似文献   

Exploring the interaction of surface roughness and slope gradient in controlling rates of soil loss from sloping farmland on the Loess Plateau of China     

Taotao Li  Longshan Zhao  Hongteng Duan  Yifan Yang  Yu Wang  Faqi Wu 《水文研究》2020,34(2):339-354

Surface roughness and slope gradient are two important factors influencing soil erosion. The objective of this study was to investigate the interaction of surface roughness and slope gradient in controlling soil loss from sloping farmland due to water erosion on the Loess Plateau, China. Following the surface features of sloping farmland in the plateau region, we manually prepared rough surfaces using four tillage practices (contour drilling, artificial digging, manual hoeing, and contour plowing), with a smooth surface as the control measure. Five slope gradients (3°, 5°, 10°, 15°, and 20°) and two rainfall intensities (60 and 90 mm/hr) were considered in the artificial rainfall simulation experiment. The results showed that the runoff volume and sediment yield increased with increasing slope gradient under the same tillage treatment. At gentle slope gradients (e.g., 3° and 5°), the increase in surface roughness prevented the runoff and sediment production, that is, the surface roughness reduced the positive effect of slope gradient on the runoff volume and sediment yield to a certain extent. At steep slope gradients, however, the enhancing effect of slope gradient on soil erosion gradually increased and surpassed the reduction effect of surface roughness. This study reveals the existence of a critical slope gradient that influences the interaction of surface roughness and slope gradient in controlling soil erosion on sloping farmland. If the slope gradient is equal to or less than the critical value, an increase in surface roughness would decrease soil erosion. Otherwise, the increase in surface roughness would be ineffective for preventing soil erosion. The critical slope gradient would be smaller under higher rainfall intensity. These findings are helpful for us to understand the process of soil erosion and relevant for supporting soil and water conservation in the Loess Plateau region of China.  相似文献   

An experimental approach for determination of the Weibull homogeneity index of rock or rock-like materials     

Pan  Xiaohua  Guo  Wei  Wu  Shifan  Chu  Jian 《Acta Geotechnica》2020,15(2):375-391

Acta Geotechnica - The spatial variation of the physical–mechanical properties of rock or rock-like materials is an intrinsic characteristic of the materials induced by multiscale material...  相似文献   

A method for aligning the plastic scintillator detector on DAMPE     

Peng-Xiong Ma  Yong-Jie Zhang  Ya-Peng Zhang  Yao Li  Jing-Jing Zang  Xiang Li  Tie-Kuang Dong  Yi-Zhong Fan  Shi-Jun Lei  Jian Wu  Yu-Hong Yu  Qiang Yuan  Chuan Yue  Zhi-Yu Sun 《天文和天体物理学研究(英文版)》2019,(6)

The Plastic Scintillator Detector(PSD) onboard the DArk Matter Particle Explorer(DAMPE)is designed to measure cosmic ray charge(Z) and to act as a veto detector for gamma ray identification.To fully exploit the charge identification potential of PSD and to enhance its capability to identify gamma ray events, we develop an alignment method for the PSD. The path length of a given track in the volume of a PSD bar is derived taking into account the shift and rotation alignment corrections. By examining energy spectra of corner-passing events and fully contained events, position shifts and rotations of all PSD bars are obtained, and are found to be on average about 1 mm and 0.0015 radian respectively. To validate the alignment method, we introduce artificial shifts and rotations of PSD bars into the detector simulation.These shift and rotation parameters can be recovered successfully by the alignment procedure. As a result of the PSD alignment procedure, the charge resolution of the PSD is improved from 4% to 8%, depending on the nuclei.  相似文献   

Mapping 3D visibility in an urban street environment from mobile LiDAR point clouds     

Yi Zhao  Jianping Wu  Song Shu  Handong Liang  Min Liu 《地理信息系统科学与遥感》2020,57(6):797-812

ABSTRACT

Visibility determination is a key requirement in a wide range of national and urban applications, such as national security, landscape management, and urban design. Mobile LiDAR point clouds can depict the urban built environment with a high level of details and accuracy. However, few three-dimensional visibility approaches have been developed for the street-level point-cloud data. Accordingly, an approach based on mobile LiDAR point clouds has been developed to map the three-dimensional visibility at the street level. The method consists of five steps: voxelization of point-cloud data, construction of lines-of-sight, construction of sectors of sight, construction of three-dimensional visible space, and calculation of volume index. The proposed approach is able to automatically measure the volume of visible space and openness at any viewpoint along a street. This approach has been applied to three study areas. The results indicated that the proposed approach enables accurate simulation of visible space as well as high-resolution (1 m × 1 m) mapping of the visible volume index. The proposed approach can make a contribution to the improvement of urban planning and design processes that aim at developing more sustainable built environments.  相似文献   

Tile‐based polygon overlay of vector data in a virtual globe     

Mengyun Zhou  Lizhe Wang  Xiaoyu Chen  Si Wu  Huawei Li 《Transactions in GIS》2020,24(4):1033-1046

The demand for analysis of large‐scale data has increased with increased access to spatial vector data. Polygon overlay of vector data in a virtual globe requires proprietary data structures and proprietary analysis algorithms. A vector data structure is designed for rapid polygon overlay in a virtual globe by recording the metadata of the triangles (TriMeta) that constitute polygons. A polygon overlay algorithm is proposed based on this data structure. The overlay of two complex GIS polygons is transformed into the intersection computation of their 3D triangular presentations. The intersection computation of two sets of triangles is reduced considerably by utilizing TriMeta to filter out the disjoint triangle pairs and rapidly identify the contained triangle. The new method improves the overlay efficiency in a virtual globe because the amount of computation required to calculate the intersections of two large polygons and drape the intersections onto a terrain surface is reduced.  相似文献   

Extracting invariant characteristics of sketch maps: Towards place query‐by‐sketch     

Ming Tang  Zoe Falomir  Christian Freksa  Yehua Sheng  Haiyang Lyu 《Transactions in GIS》2020,24(4):903-943

In geography, invariant aspects of sketches are essential to study because they reflect the human perception of real‐world places. A person's perception of a place can be expressed in sketches. In this article, we quantitatively and qualitatively analyzed the characteristics of single objects and characteristics among objects in sketches and the real world to find reliable invariants that can be used to establish references/correspondences between sketch and world in a matching process. These characteristics include category, shape, name, and relative size of each object. Moreover, quantity and spatial relationships—such as topological, ordering, and location relationships—among all objects are also analyzed to assess consistency between sketched and actual places. The approach presented in this study extracts the reliable invariants for query‐by‐sketch and prioritizes their relevance for a sketch‐map matching process.  相似文献   

测绘地理信息档案管理对策研究     

李明 《测绘与空间地理信息》2020,(3):9-11,15

国民经济建设对测绘地理信息档案的需求旺盛,如何对测绘地理信息数据进行归档管理,提高测绘地理信息档案存储的安全性及方便再利用,已经成为测绘地理信息档案管理部门需要研究的重要课题。本文通过分析当前测绘地理信息档案管理的现状,指出存在的问题,提出有力的改进措施。  相似文献