融合深度相机点云与光学影像的室内三维建模   总被引：1，自引：0，他引：1  

张恬洁  康志忠 《测绘科学》2016,41(12):217-223

针对传统的对点云进行拼接建模的方法无法得到较好的室内三维模型的问题,该文提出了一种融合Kinect点云与光学影像数据的室内三维建模方法:首先,利用Agisoft Photoscan软件对Kinect获得的彩色影像进行处理获得大量三维点,并与拼接后的Kinect点云进行融合,从而弥补Kinect点云缺失严重的现象;然后,针对不同的物体利用不同的方法对融合后的点云数据进行处理,并通过"孔洞算法"提取其边界点;最后,将边界点进行处理从而完成室内三维场景模型。实验结果表明,该文方法能够提供质量较高的三维点云数据,并且能得到较好的室内三维模型。  相似文献   

基于原状土柱土壤水分传感器率定方法的研究   总被引：3，自引：1，他引：2       下载免费PDF全文

智永明  韩继伟  邓超  张松明  邓彬  何生荣  刘满红  施露阳 《水文》2016,36(4):48-52

土壤水分传感器在现场安装后,需要针对现场土壤状况对其进行率定,以便校准率定关系。在工程实践中,土壤水分传感器现场率定是一项步骤繁杂、操作要求高、现场取土难度大、耗时较长的一项工作,严重困扰工程项目的实施。开展基于原状土柱率定土壤水分传感器研究,通过现场采集原状土柱,在实验室浸泡至饱和后取出,让土壤水分自然散失,用称重法定期称量原状土柱重量,同时记录土壤水分传感器原始测量值,以此来研究土壤水分传感器的工程率定问题,探讨提高现场安装的土壤水分传感器率定效率的方法,具有现实意义。  相似文献   

Effects of juniper removal and rainfall variation on tree transpiration in a semi‐arid karst: evidence of complex water storage dynamics          下载免费PDF全文

Heather Cardella Dammeyer  Susanne Schwinning  Benjamin F. Schwartz  Georgianne W. Moore 《水文研究》2016,30(24):4568-4581

Brush removal is widely practiced as a tool for increasing groundwater recharge, but its efficacy depends greatly on the way in which the removed species interact with the hydrological system relative to the vegetation replacing it. We examined the effects of Ashe juniper removal in the recharge zone of the Edwards Aquifer, Texas, USA, a karst aquifer. The study was conducted in an Ashe juniper (Juniperus ashei)–live oak (Quercus fusiformis) woodland on a hill slope composed of rocky, shallow soils over fractured limestone bedrock. Ashe juniper is a native species that has been encroaching grasslands and savannas over the past century. In September 2008, a plot was cleared of 90% of its juniper trees. Tree transpiration, predawn water potentials and vegetation cover across the cleared plot and an adjacent reference site were measured from May 2009 to December 2011. Stand‐level tree transpiration from May 2009 to March 2010 was diminished by a severe summer drought in 2009, from which trees were slow to recover. Subsequently, tree transpiration was 5–10× higher in the woodland compared to the clearing. For all of 2011, also a drought year, tree transpiration in the woodland exceeded precipitation inputs, indicating a high capacity for water storage at the study site. However, site differences for oak trees were generally larger than for juniper trees. While juniper removal accounted for a 431 mm year^?1 difference in tree transpiration between sites, vegetation cover in the clearing increased from 42% to 90% over two years, suggesting that understory growth was increasingly compensating for the loss of juniper transpiration. We conclude that the removal of a relatively shallow‐rooted tree, when replaced with herbaceous vegetation and low shrubs, has little effect on deep recharge. By contrast, successive years of precipitation extremes may be more effective increasing recharge by lowering the water transport capacity of trees in the aftermath of severe drought. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

On the controls of preferential flow in soils of different hillslope position and lithological origin     

Qicheng Tang  Jonathan M. Duncan  Li Guo  Henry Lin  Dacheng Xiao  David M. Eissenstat 《水文研究》2020,34(22):4295-4306

Soils derived from different lithologies and their controls on preferential flow remain underexplored in forested landscapes. In the same lithology, the propensity for preferential flow occurrence at different hillslope positions also remains largely elusive. By utilizing a soil moisture response time method, we compared preferential flow occurrence between a shale site (Shale Hills, silt loam soils) and a sandstone site (Garner Run, sandy loam soils) at four hillslope positions: ridge-top, North- and South-facing mid-slopes and toe slope, for over 2 years. The catchments are neighbouring and covered by temperate forest. For the four hillslope positions, Shale Hills had higher preferential flow frequencies compared to Garner Run. Between these two catchments, the South-facing mid-slope sites showed the highest contrasts in preferential flow frequency (33.5% of events at Shale Hills vs. 8.8% at Garner Run) while the ridge-top sites showed the lowest contrasts (18.7 vs. 13.2%). Additionally, over the unfrozen period, for seven out of eight monitoring sites, drier antecedent conditions tended to be more favourable for preferential flows to occur, with significant (p < .01) relationships at two sites. Except for the South-facing mid-slope sites, both Shale Hills and Garner Run had two preferential flow pathways. The characteristic preferential flow pathways at Shale Hills were the B_w and C horizons, and for Garner Run, preferential flow moved from the E/AE horizon to the B_w horizon. This study shows that shale-derived soils tended to have higher preferential flow occurrence than sandstone soils, but hillslope positions exhibit different levels of contrasts. More effort should be paid to study the impact of lithology on preferential flows in the context of land surface modelling and biogeochemical reactions to improve ecosystem services of headwater catchments.  相似文献   

An Investigation into Effect of Randomly Distributed Small Scale          下载免费PDF全文

LUO Zhexian  LI Chunhu 《Acta Meteorologica Sinica》2008,22(2):143-151

Previous studies concerning the interaction of dual vortices have been made generally in the deterministic framework. In this paper, by using an advection equation model, eight numerical experiments whose integration times are 30 h are performed in order to analyze the interaction of dual vortices and the vortex self-organization in a coexisting system of deterministic and stochastic components. The stochastic components are introduced into the model by the way that the Iwayama scheme is used to produce the randomly distributed small-scale vortices which are then added into the initial field. The different intensity of the small-scale vortices is described by parameter K being 0.0, 0.4, 0.6, 0.8, and 1.0, respectively. When there is no small-scale vortex （K=0.0）, two initially separated meso-beta vortices rotate counterclockwise mutually, and their quasi-final flow pattern is still two separated vortices; after initially incorporating small-scale vortices （K=0.8, 1.0）, the two separated meso-beta vortices of initially same intensity gradually evolve into a major and a secondary vortex in time integration. The major vortex pulls the secondary one, which gradually evolves into the spiral band of the major vortex. The quasi-final flow pattern is a self-organized vortex with typhoon-like circulation, and the relative vorticity at its center increases with increasing in K value, suggesting that small-scale vortices feed the self-organized vortex with vorticity. This may be a possible mechanism responsible for changes in the strength of the self-organized vortex. Results also show that the quasi-final pattern not only relates with the initial intensity of the small-scale vortices, but also with their initial distribution. In addition, three experiments are also performed in the case of various boundary conditions. Firstly, the periodic condition is used on the E-W boundary, but the fixed condition on the S-N boundary; secondly, the fixed condition is set on all the boundaries; and thirdly, the periodic conditio  相似文献   

On the suitability of 1 s geophone for ambient noise measurements in the 0.1–20Hz frequency range: experimental outcomes     

A. Strollo  D. Bindi  S. Parolai  K.-H. Jäckel 《Bulletin of Earthquake Engineering》2008,6(1):141-147

Following the ongoing debate about suitability of short-period sensor for seismic noise measurements at frequencies lower than 1 Hz, in this study we compare recordings from two different seismometers (Güralp CMG-3ESPC and Mark L4C-3D) installed side by side in the GeoForschungsZentrum laboratory. The comparison carried out in terms of Power Spectral Density and coherency analysis shows an excellent agreement between the short-period and the broad-band recordings in the frequency band 0.2–20 Hz. Therefore, this result highlights that with a calibrated short-period sensor one can obtain the same results that would be obtained by using a broad-band seismometer in the band of engineering interest.  相似文献   

高温超导磁强计在电偶源瞬变电磁法中的应用     

陈晓东  赵毅  林天亮  杨涛  戴远东 《物探与化探》2012,(1):65-68

研制了适用于电偶源瞬变电磁法中直接测量磁感应强度B的高温超导磁强计,并进行了电偶源瞬变电磁法大地电磁测量野外实验。测量结果表明了高温超导磁强计明显优于常规感应线圈探头,可以得到更深的探测深度。  相似文献   

近钻头随钻测量系统及其小型化设计关键技术分析          下载免费PDF全文

韦海瑞  朱芝同  吴川  邵玉涛  赵洪波  刘广  贾炜  董巍  张化民  贾明浩  薛倩冰 《探矿工程》2022,49(5):156-162

近钻头随钻测量技术是石油钻井领域最具有发展前景的高新技术之一,它以近钻头地质参数与工程参数的随钻测量、传输、信息解释、决策控制为主要技术特征,能有效提高油气层钻遇率、降低钻井成本。本文介绍了近钻头测量系统国内外的发展与应用现状,阐述了系统的工作原理、结构组成与特点,为满足小口径钻进对近钻头测量技术的需求,提出了小型化设计亟待攻克的关键技术难题,包括电磁波无线通信抗干扰技术、小直径涡轮发电技术、井下MEMS传感器技术等,为今后小直径近钻头测量系统研发提供技术基础。  相似文献   

悬空管线的振动特性分析   总被引：5，自引：0，他引：5  

唐友刚  李长升  李小敏 《海洋工程》1995,(1)

埋地管线穿河段由于河水冲刷而悬空，在水流作用下诱发涡激振动。本文在实测悬空管线固有频率的基础上，提出了其固有频率的计算方法。按本文方法所得结果和实测结果基本吻合。  相似文献   

光纤光栅应变传感器在地质灾害上的应用     

曾克 《物探与化探》2014,(1):142-144,156

根据光纤光栅传感的原理,提出了光纤光栅式封装应变传感器,对其传感特性进行了研究,并进行了室内实验。结合光栅传感监测滑坡的应用实例,探讨了光纤布拉格光栅传感元件在滑坡体上的布设工艺及监测过程。分析初期的监测结果,针对监测系统可能出现的问题提出了解决途径。  相似文献