Fully coupled elastoplastic hydro-mechanical analysis of unsaturated porous media using a meshfree method     

Omid Ghaffaripour  Golnaz A. Esgandani  Arman Khoshghalb  Babak Shahbodaghkhan 《国际地质力学数值与分析法杂志》2019,43(11):1919-1955

This paper presents the first application of an advanced meshfree method, ie, the edge-based smoothed point interpolation method (ESPIM), in simulation of the coupled hydro-mechanical behaviour of unsaturated porous media. In the proposed technique, the problem domain is spatially discretised using a triangular background mesh, and the polynomial point interpolation method combined with a simple node selection scheme is adopted for creating nodal shape functions. Smoothing domains are formed on top of the background mesh, and a constant smoothed strain, created by applying the smoothing operation over the smoothing domains, is assigned to each smoothing domain. The deformation and flow models are developed based on the equilibrium equation of the mixture, and linear momentum and mass balance equations of the fluid phases, respectively. The effective stress approach is followed to account for the coupling between the flow and deformation models. Further coupling among the phases is captured through a hysteretic soil water retention model that evolves with changes in void ratio. An advanced elastoplastic constitutive model within the context of the bounding surface plasticity theory is employed for predicting the nonlinear behaviour of soil skeleton. Time discretisation is performed by adopting a three-point discretisation method with growing time steps to avoid temporal instabilities. A modified Newton-Raphson framework is designed for dealing with nonlinearities of the discretised system of equations. The performance of the numerical model is examined through a number of numerical examples. The state-of-the-art computational scheme developed is useful for simulation of geotechnical engineering problems involving unsaturated soils.  相似文献   

基于圆柱多段拟合的隧道中轴线提取方法研究     

荆海峰  李广云  王力  杨文锋 《大地测量与地球动力学》2018,38(2):211-215

提出基于圆柱多段拟合的隧道中轴线提取方法。首先对隧道点云数据进行预处理，并将点云按隧道走向分成不同区段；然后对各区段依据轴线与表面点云法线垂直关系，提取精度较低的中轴线；最后对各区段利用圆柱多段拟合，提取精度较高的中轴线。实验表明，隧道中轴线的提取在一定的采样区间具有较高的稳定性，对直线和弯曲的圆形隧道有良好的适用性，算法可靠，精度较高。  相似文献   

一种由粗到精的地面激光点云多层级配准方法     

王英  张云生 《测绘与空间地理信息》2020,(2):156-159

提出了一种综合利用快速点特征直方图(FPFH)描述符和同名点引导ICP优化的地面激光扫描(TLS)点云配准方法。该方法包括3个步骤:1)点云金字塔构建;2)基于FPFH的粗配准;3)同名点引导的ICP精配准。首先使用体素网格滤波器构造点云的金字塔结构,在粗配准时,FPFH描述符用于金字塔顶层上点云的鲁棒匹配,在此基础上,再进行两层级同名点引导的ICP精配准优化,使用3组典型TLS点云对进行实验,结果表明本文方法可以高效地完成TLS点云的配准。  相似文献   

Fast genetic mapping in barley: case studies of cuticle mutants using RNA-sequencing     

XiaoFeng Li  Chao Li  Qin Zhou  GuoXiong Chen  PengShan Zhao 《寒旱区科学》2020,12(3):180-188

Barley(Hordeum vulgare L.) is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide. Forward genetic studies in barley have greatly advanced plant genetics during the last century; however, most genes are identified by the conventional mapping method. Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations, but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley. This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing. The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions. Detailed information on the mapping-by-sequencing, mapping-and-sequencing, and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed. The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping, especially for laboratories without large funding.  相似文献   

青藏块体东北缘断层形变与中强地震   总被引：7，自引：4，他引：3  

陈兵  江在森  马文静  黎凯武  薛富平 《大地测量与地球动力学》2002,22(4):49-55

对祁连山－海原断裂带近期断层形变特征进行了初步研究，发现多场地，大范围的断层活动异常是中等强度地震发生的显著背景，并且往往与大陆地震活动的阶段性总体状况相呼应；区域形变存在明显的特征量，包括特征形态和特征时间，同一场地在不同地震前的异常特征具有重复性，但会受到背景差异显著的不同地震的影响，目前形变状况表明研究区仍具有发生中强地震的地壳运动背景。  相似文献   

基于SAR干涉点目标分析技术的城市地表形变监测   总被引：1，自引：0，他引：1  

张永红  张继贤  龚文瑜  LU Z 《测绘学报》2009,38(6)

通过深入研究干涉点目标的相位模型,提出基于空间搜索的邻近点目标干涉相位差解缠方法,用以计算点目标的地形残差和线性形变,以及分离点目标大气延迟相位和非线性形变相位的时空域滤波方法,解决干涉点目标分析中的关键问题.最后,以苏州地区地表沉降监测为应用试验,利用形成的SAR干涉点目标形变信息提取技术,获取苏州市区1992-2002年间的地表沉降信息.研究结果与已有文献记录保持比较好的一致性,证明SAR干涉点目标技术完全可以发展成为应用于城市地表形变监测的实用化技术.

Abstract：

Interferometric point target analysis (IPTA) is one of the latest developments in radar interferometric processing. It is achieved by analysis of the interferometric phases of some individual point targets, which are discrete and present temporarily stable backscattering characteristics, in long temporal series of interferometric SAR images. This paper analyzes the interferometric phase model of point targets, and then addresses two key issues within IPTA process. Firstly, a spatial searching method is proposed to unwrap the interferometric phase difference between two neighboring point targets. The height residual error and linear deformation rate of each point target can then be calculated, when a global reference point with known height correction and deformation history is chosen. Secondly, a spatial-temporal filtering scheme is proposed to further separate the atmosphere phase and nonlinear deformation phase from the residual interferometric phase. Finally, an experiment of the developed IPTA methodology is conducted over Suzhou urban area. Totally 38 ERS-1/2 SAR scenes are analyzed, and the deformation information over 3 546 point targets in the time span of 1992-2002 are generated. The IPTA-derivecl deformation shows very good agreement with the published result, which demonstrates that the IPTA technique can be developed into an operational tool to map the ground subsidence over urban area.  相似文献   

影响鸢乌贼手钓上钩率的因子探讨     

吴国峰  陈新军 《广东海洋大学学报》2006,26(6):35-38

根据印度洋西北部鸢乌贼（Sym plectoteuthis oualaniensis）作业渔场的现场调查数据．分析了作业水深、作业时段、摄食等级和月相等因子对手钓上钩率的影响。统计表明．晚上、午夜和凌晨3个不同时段和不同作业水深对手钓上钩率均有显著性影响。3个时段中，其摄食等级呈先低后高再低的现象。午夜和凌展，上钩率的变化趋势与摄食等级的变化趋势呈显著的负相关。在月相的影响下．离朔日三四天之前，手钓产量呈上升趋势；离望日五六天之前。手钓产量呈明显的下降趋势。  相似文献   

试论企业组织结构--电子商务企业与传统企业的比较     

何兴贵  黄宗捷 《成都信息工程学院学报》2002,17(3):196-199

网络时代的到来，对传统企业的组织结构、运作模式、管理方法均提出了严峻的挑战。传统的企业组织结构是适应大工业生产而形成的等级组织结构形式，它有很大的局限性；电子商务企业的组织结构是适应网络社会而形成扁平化、双向多对多、以信息为基础的新型组织结构形式。电子商务企业以其组织结构扁平化和中空化，决策分散化，运作虚拟化，灵活高效为特点，它将成为传统企业在电子商务发展阶段变革的方向和目标。  相似文献   

A Simulating Experiment in the Process of Soil Erosion on Bare Land in Mt. Tanakami     

ZHAO Wei  HU Ke  Wang Xikui  Akitsu Kimoto  Takahisa MIZUYAMA 《世界地质(英文版)》2001,4(2)

In order to understand the process of surface erosion and acquire basic data of conditions on hillslope without vege tation, a sprinkling experiment is conducted on a bare slope in Mt. Tanakami in the central part of Japan. Based on the mea surements of runoff, mean soil erosion depth, and sediment yield, etc. , the results suggest the following characteristics in the process of surface erosion in the experimental area. (1) The occurrence of sediment discharge is interrupted; (2) Surface runoff is a saturated overland flow; (3) The mean soil erosion depth is thick compared with other areas in Mt. Tanakami;(4) Sediment discharge process is detachment- limited.  相似文献   

广西森林旅游资源的特色及其开发意义     

傅中平  黄载环 《南方国土资源》2001,14(3):27-29

广西森林旅游资源多达 816 .7万hm2 ,景点 2 80个 ,内容丰富 ,前景广阔 ,加强广西森林旅游资源特色的开发 ,有利于促进广西旅游业可持续发展 ,有利于经济、社会、环境效益的提高及人们的文化素质和生活质量的提高。  相似文献