体育馆屋盖结构的非接触式实时沉降监测     

刘尚国  于胜文  郑文华  张宏芽 《测绘科学》2012,37(3):85-86,92

本文针对某体育馆屋盖结构沉降监测的任务要求,采用了基于经纬仪或全站仪角度观测的非接触式沉降监测方法;论述了其测量原理及详细的作业过程,在论证测距误差及水平位移对沉降量计算影响可忽略不计的基础上,分析了该方法可达到的精度水平。为满足实时性监测的要求,采用Visual Basic语言编制了联机测量程序,实时记录和存储观测数据及计算成果。工程实践表明,该方法能够在水准测量无法实施的情况下,有效解决不易到达变形体的沉降监测难题。  相似文献   

基于改进RANSAC算法的复杂建筑物屋顶点云分割     

刘亚坤  李永强  刘会云  孙渡  赵上斌 《地球信息科学学报》2021,23(8):1497-1507

屋顶模型重建影响到建筑物完整模型重建质量,屋顶面点云分割质量对屋顶模型重建具有重要意义。针对传统RANSAC算法在屋顶点云面片分割时易产生错分割、过分割等问题,本文顾及点云位置信息,提出一种对点云重新分配的改进RANSAC点云分割算法。算法暂时剔除非平面内点,选取平面内点集中3个点作为初始样本,平面拟合判定邻域是否有效,从有效邻域中选取标准差值最小的3个点为初始模型。利用RANSAC算法对屋顶点云进行分割。利用K近邻算法统计误分类点与面片的距离降低误分类,优化过分割面片并进行连通性分析,利用距离及法向量一致性检验的方法重分配非平面内点。为验证本文算法有效性,选取芬兰Helsinki地区的3栋相互独立的复杂建筑物屋顶以及上海某小区的6栋建筑物群屋顶作为实验数据。在2组数据中,本文提出的改进RANSAC算法分割屋顶面片的平均准确率分别为92.17%、87.82%,78%的建筑物屋顶不存在过分割。在第2组数据中,所有分割面片上的点与其对应的最佳拟合平面的距离的标准差的平均值为0.030 m。实验结果表明,本文算法分割建筑物屋顶面片的准确率较高,较好的抑制了过分割现象,且抗噪能力强。  相似文献   

坚硬顶板煤层一次采全高顶板支护管理研究     

李建璞  杨小彬  刘伟  李艳强 《地质与勘探》2012,48(6):1229-1233

大采高综采技术是厚煤层开采工艺的重要发展方向,越来越多地被采用,顶板事故在矿山生产安全事故中占有较大比例,有效控制顶板,合理对顶板进行支护是采矿过程中必须认真考虑的问题。大采高综采工作面采场顶板跨度大、高度高,矿山压力复杂,管理难道大,本文针对某矿9、10号煤层大采高综采工作面顶板坚硬特性,通过理论计算出了不同工作条件下支架工作阻力和顶板支护强度参数,结合对本矿区所做的相似模拟实验结论,对顶板管理中支护强度进行了分析研究,就矿区特定顶板条件选定和提出了具体支护要求。  相似文献   

坚硬顶板诱发煤体冲击破坏的微震效应   总被引：7，自引：2，他引：5       下载免费PDF全文

陆菜平  窦林名  王耀峰  杜涛涛 《地球物理学报》2010,53(2):450-456

利用TDS-6微震采集系统测试了忻州窑煤矿组合煤岩试样变形破裂直至冲击破坏过程中的微震信号,特别是冲击破坏前后微震频谱的变化规律.采用SOS微震监测系统,对忻州窑煤矿8929工作面冲击矿压的微震活动规律进行了监测,结果表明：（1）冲击前兆信号呈现低频特征,随着与主震间隔的时间越短,主频越低.主震信号频谱较宽,但低频（0～50 Hz）成份增加,余震信号呈现高频特性.（2）微震信号的频次、累积能量与主频之间呈负相关关系.尤其当工作面顶板来压以及诱发冲击矿压时,微震信号的主频达到最低值.（3）现场监测表明,冲击前兆微震信号的主频为0～50 Hz,且振幅较低.冲击主震信号频谱较宽,但较低频（0～20 Hz）成份明显增加,同时振幅达到极值.余震信号主频为0～200 Hz,呈现高频、低振幅特征.  相似文献   

Roof model recommendation for complex buildings based on combination rules and symmetry features in footprints     

Xuke Hu  Alexey Noskov 《International Journal of Digital Earth》2018,11(10):1039-1063

Currently, very few roof shape information for complex buildings is available on OSM. Moreover, additional data requirements (e.g. 3D point clouds) limit the applicability of many roof reconstruction approaches. To mitigate this issue, we propose an approach to roof shape recommendations for complex buildings by exploring the inherited characteristics of building footprints: the disclosure of rectangles combinations in a partition of footprints and the symmetrical features of footprints. First, it decomposes a complex footprint into rectangles by using an advanced minimal non-overlapping cover algorithm. Second, a graph-based symmetry detection algorithm is proposed to identify all the symmetrical sub-clusters in partitions. Then, a set of selection rules are defined to rank partitions, and the best ones are chosen for roof shape recommendation. Finally, a set of combination rules and a symmetry rule are defined. It enables to evaluate the probability of a footprint being a certain combination of roof shapes. Experimental results show the growth of the probability of correctly recommending roof shapes for single rectangles and buildings from a prior probability of 17–45% and from a prior probability of 0.29–14.3%, removing 60% and 93% of the incorrect roof shape options, respectively.  相似文献   

巷旁切顶对采场下位岩层垮落特征的影响机制     

刘斌慧  杨军  田锋  付强 《岩土力学》2023,44(1):289-302

巷旁切顶打断了巷道与采场下位顶板的连续性,促进了采场顶板垮落形成碎石帮,深入研究切顶对采场下位岩层垮落特征的影响机制具有重要意义。对采场支架载荷进行了分析,并对上覆岩层建立了力学建模,明确了上覆岩层运动与典型位置采场支架载荷特征的关系。在此基础上,针对6个巷旁切顶的工作面,给出了典型位置支架的载荷数据,从而分析得到巷旁切顶对采场下位岩层垮落特征的影响机制。同时,建立了数值模型,分析了不同的切顶起始位置和下位顶板强度对下位岩层垮落特征的影响。结果表明,121工法的“垮落线”具有对称的弧形边界,110工法的“垮落线”在切顶侧向工作面充分移动,N00工法介于上述两者之间。此外,不同切顶起始位置和顶板强度条件下,切顶的作用效果存在差异。研究结果有利于进一步深化巷旁切顶对采场下位岩层垮落特征影响的认识。  相似文献   

A note on estimating urban roof runoff with a forest evaporation model     

J. H. C. Gash  P. T. W. Rosier  R. Ragab 《水文研究》2008,22(8):1230-1233

A model developed for estimating the evaporation of rainfall intercepted by forest canopies is applied to estimate measurements of the average runoff from the roofs of six houses made in a previous study of hydrological processes in an urban environment. The model is applied using values of the mean rates of wet canopy evaporation and rainfall derived previously for forests and an estimate of the roof storage capacity derived from the data collected in the previous study. Although the model prediction is sensitive to the value of storage capacity, close correlation between the modelled and measured runoff indicates that the model captures the essential processes. It is concluded that the process of evaporation from an urban roof is sufficiently similar to that from a forest canopy for forest evaporation models to be used to give a useful estimate of urban roof runoff. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

True orthoimage generation by mutual recovery of occlusion areas     

Eun Jin Yoo 《地理信息系统科学与遥感》2016,53(2):227-246

Demand for orthoimages is increasing as a crucial component of geographic information systems (GISs). Orthoimages are geometrically equivalent to planimetric maps, which show true geographic locations of terrain features. To produce orthoimages, geometric distortions from camera tilt and relief displacement from perspective images must be corrected. Traditionally, removing such distortions has been accomplished by differential rectification in a pixel-by-pixel fashion. However, this method cannot produce true orthoimages because of the double-mapping problem. We propose a method of generating patch-based true orthoimages for surface patches in buildings. The proposed method utilizes three-dimensional (3D) building model data. Patches from the data were projected onto aerial images to extract image patches and analysis of the superstructures was performed. Because orthoimages are generated for each building, the orthoimage quality is enhanced when using building data with a high level of detail. Instead of performing the complex visibility analysis of existing approaches, this article identifies occlusion areas based on unit surfaces of buildings and presents mutual recovery of occlusions using multiple images. To evaluate the feasibility of the method, experiments were performed with real datasets: (1) a building with a dome superstructure, (2) high-rise buildings close to each other, and (3) buildings with various shapes.  相似文献   

基于二阶局部纹理熵的边缘检测方法     

刘宸  刘智  刘长建  徐奥 《测绘科学技术学报》2017,34(1)

针对传统的边缘检测方法将灰度变化较为平缓的区域误判为边缘的问题,提出了基于二阶局部纹理熵的边缘检测方法。利用了二阶局部纹理熵能表示局部区域灰度变化大小的性质,并采用灰度错位压缩法消除灰度值压缩造成的条纹现象。实验表明,本文提出的方法能有效地检测出各类边缘,解决了上述的误判问题;通过不同大小窗口的边缘检测效果比较,建议在采用基于二阶局部纹理熵的边缘检测方法时将窗口设置为3×3。  相似文献   

矿井顶板水害预测与防治专家系统     

刘光庆  于旭磊  李凤海  张文泉  刘伟韬  李家祥 《中国地质灾害与防治学报》2001,12(1):71-74

影响顶板水涌出的因素是多方面的，不仅与含水层本身的类型、特征、赋存条件有关，而且还与煤层顶板各隔水岩层的水文地质条件、地层结构及采矿地质条件有关。本文在分析矿井顶板水危害现状及相关专家系统研究概况的基础上，研究了顶板富水性分区的影响因素，以信息拟合方法完成了顶板富水性分区，并以此为基础，结合模糊理论，完成了综合模糊评判决策系统，最后进行了实例验证。  相似文献