单线激光雷达扫描的矿车装载量核算方法     

逯行政  许志华  徐二帅  毛亚纯 《测绘通报》2021,(7):12-16

面向露天矿山生产对于矿车装载量核算的需求,本文提出了一种利用单线激光雷达扫描的矿车装载量自动核算方法。该方法首先采用固定式单线激光雷达对目标车辆进行俯视扫描,基于车辆形态特征分割出载荷物顶部点云;然后经时态校正,并与预先构建的车辆信息数据库进行匹配,重建出载荷物的三维表面模型;最后通过对载荷物表面模型的切片积分实现方量核算。以齐大山铁矿运输为例,对多台矿车装载量进行核算测试。结果表明,本文方法可在车辆正常行驶的情况下实时获取载荷物的表面三维点云,平均建模误差为2.54 cm,装载方量核算误差为1.17%。  相似文献   

Water mining from the deep critical zone by apple trees growing on loess     

Huijie Li  Bingcheng Si  Pute Wu  Jeffrey J. McDonnell 《水文研究》2019,33(2):320-327

There have been significant recent advances in understanding the ecohydrology of deep soil. However, the links between root development and water usage in the deep critical zone remains poorly understood. To clarify the interaction between water use and root development in deep soil, we investigated soil water and root profiles beyond maximum rooting depth in five apple orchards planted on farmland with stand ages of 8, 11, 15, 18, and 22 years in a subhumid region on the Chinese Loess Plateau. Apple trees rooted progressively deeper for water with increasing stand age and reached 23.2 ± 0.8 m for the 22‐year‐old trees. Soil water deficit in deep soil increased with tree age and was 1,530 ± 43 mm for a stand age of 22 years. Measured root deepening rate was far great than the reported pore water velocity, which demonstrated that trees are mining resident old water. The deficits are not replenished during the life‐span of the orchard, showing a one‐way mining of the critical zone water. The one‐way root water mining may have changed the fine root profile from an exponential pattern in the 8‐year‐old orchard to a relative uniform distribution in older orchards. Our findings enhance our understanding of water‐root interaction in deep soil and reveal the unintended consequences of critical zone dewatering during the lifespan of apple trees.  相似文献   

空间互相关方法在分析海底沙波迁移规律中的应用     

甘雨  马小川  阎军 《海洋学报》2019,41(4):42-52

海底沙波具有显著的活动性并能够对海底工程设施造成潜在威胁，因此对海底沙波活动性的评估一直以来受到广泛关注。目前大多数研究者仍利用平面剖面对比来分析海底沙波的迁移特征。然而，该方法难以全面高效地获取海底沙波二维平面迁移矢量。本文基于2007年和2009年的高分辨率多波束测深数据，详细阐述了空间互相关方法在分析北部湾东南海域海底沙波迁移规律中的应用过程。利用实测数据进行对比分析，获得了研究区海底沙波的活动特征，并进一步讨论了空间互相关算法中不同参数的选取对结果的影响。结果显示，利用空间互相关分析方法能够有效获取海底沙波二维迁移矢量，获得的海底沙波迁移速率和迁移方向与前人研究成果吻合，表明了该方法的可行性和可靠性。但在对实际DTM数据进行空间互相关分析时，需根据海底沙波形态、数据质量等因素选取合适的参数及矢量获取方法。本研究实验了一种确定海底沙波迁移规律的新方法，该方法将有效提升获得海底地形变化规律的效率和准确度，可获得更加精细的海底地形动力过程。  相似文献   

基于时空聚类的出租车载客热点区域挖掘研究     

何月  王崇倡 《测绘与空间地理信息》2020,(1):99-102

针对出租车运营过程缺少路径优化指导造成运营能力分布不均、空载率高的问题,本文以成都市安装有GPS设备的出租车所采集的轨迹数据为研究对象,以提高出租车效益为目标,采用了一种基于网格的出租车载客热点聚类算法,通过对出租车GPS轨迹数据进行处理和聚类分析,充分挖掘出租车载客热点区域,从而为出租车的运营者和管理者提供信息决策服务。  相似文献   

Erodibility of low‐compaction steep‐sloped reclaimed surface mine lands in the southern Appalachian region,USA          下载免费PDF全文

Siavash Hoomehr  John S. Schwartz  Daniel Yoder  Eric C. Drumm  Wesley Wright 《水文研究》2015,29(3):321-338

The use of loose spoils on steep slopes for surface coal mining reclamation sites has been promoted by the US Department of Interior, Office of Surface Mining for the establishment of native forest, as prescribed by the Forest Reclamation Approach (FRA). Although low‐compaction spoils improve tree survival and growth, erodibility on steep slopes was suspected to increase. This study quantified a combined K_C factor (combining the effects of the soil erodibility K factor and cover management C) for low compaction, steep‐sloped (>20°) reclaimed mine lands in the Appalachian region, USA. The combined K_C factor was used because standard Unit Plot conditions required to separate these factors, per Revised Universal Soil Loss Equation (RUSLE) experimental protocols, were not followed explicitly. Three active coal mining sites in the Appalachian region of East Tennessee, each containing four replicate field plots, were monitored for rainfall and sediment yields during a 14‐month period beginning June 2009. Average cumulative erosivity for the study sites during the monitoring period was measured as 5248.9 MJ·mm·ha^?1·h^?1. The K_C ranged between 0.001 and 0.05 t·ha·h·ha^?1·MJ^?1·mm^?1, with the highest values occurring immediately following reclamation site construction as rills developed (June – August 2009). The K_C for two study sites with about an 18–20 mm spoil D₈₄ were above 0.01 t·ha·h·ha^?1·MJ^?1·mm^?1 during rill development, and below 0.003 t·ha·h·ha^?1·MJ^?1·mm^?1 after August 2009 for the post‐rill development period. The K_C values for one site with a 40 mm spoil D₈₄ were never above 0.008 t·ha·h·ha^?1·MJ^?1·mm^?1 and also on average were lower, being more similar to the other two sites after the rill development period. Based on an initial K_C factor (K_e) measured during the first few storm events, the average C factor (C_e) was estimated as 0.58 for the rill development period and 0.13 for the post‐rill development period. It appears that larger size fractions of spoils influence K_C and C_e factors on low‐compaction steep slopes reclamation sites. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

海水海砂混凝土双K断裂参数的确定   总被引：1，自引：1，他引：0  

臧朝会  杨树桐  金亮亮 《海洋工程》2019,37(4):142-150

采用尺寸为515 mm×100 mm×100 mm初始缝高比从0.1变化至0.8的三点弯曲梁试件,利用试验测得起裂荷载Pini、最大荷载Pmax及对应的裂缝口张开位移CMODc等参数,研究了缝高比a0/h对海水海砂混凝土双K断裂参数的影响。并以相同配合比的淡水河砂梁作为对照组,进一步研究了海砂海水混凝土双K断裂参数与普通混凝土之间的关系。结果发现海水海砂混凝土断裂参数在a0/h=0.25～0.7范围内时可以认为是一常数;海水海砂混凝土梁断裂参数比相同配合比情况下的淡水河砂梁大且对边界影响更加敏感。  相似文献   

Soil property variation mapping through data mining of soil category maps          下载免费PDF全文

Fei Du  A‐Xing Zhu  Lawrence Band  Jing Liu 《水文研究》2015,29(11):2491-2503

Spatial information on soil properties is an important input to hydrological models. In current hydrological modelling practices, soil property information is often derived from soil category maps by the linking method in which a representative soil property value is linked to each soil polygon. Limited by the area‐class nature of soil category maps, the derived soil property variation is discontinuous and less detailed than high resolution digital terrain or remote sensing data. This research proposed dmSoil, a data‐mining‐based approach to derive continuous and spatially detailed soil property information from soil category maps. First, the soil–environment relationships are extracted through data mining of a soil map. The similarity of the soil at each location to different soil types in the soil map is then estimated using the mined relationships. Prediction of soil property values at each location is made by combining the similarities of the soil at that location to different soil types and the representative soil property values of these soil types. The new approach was applied in the Raffelson Watershed and Pleasant Valley in the Driftless Area of Wisconsin, United States to map soil A horizon texture (in both areas) and depth to soil C horizon (in Pleasant Valley). The property maps from the dmSoil approach capture the spatial gradation and details of soil properties better than those from the linking method. The new approach also shows consistent accuracy improvement at validation points. In addition to the improved performances, the inputs for the dmSoil approach are easy to prepare, and the approach itself is simple to deploy. It provides an effective way to derive better soil property information from soil category maps for hydrological modelling. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Selection of sand models and identification of parameters using an enhanced genetic algorithm          下载免费PDF全文

Yin‐Fu Jin  Zhen‐Yu Yin  Shui‐Long Shen  Pierre‐Yves Hicher 《国际地质力学数值与分析法杂志》2016,40(8):1219-1240

Numerous constitutive models of granular soils have been developed during the last few decades. As a consequence, how to select an appropriate model with the necessary features based on conventional tests and with an easy way of identifying parameters for geotechnical applications has become a major issue. This paper aims to discuss the selection of sand models and parameters identification by using genetic algorithm. A real‐coded genetic algorithm is enhanced for the optimization with high efficiency. Models with gradually varying features (elastic‐perfectly plastic modelling, nonlinear stress–strain hardening, critical state concept and two‐surface concept) are selected from numerous sand models as examples for optimization. Conventional triaxial tests on Hostun sand are selected as the objectives in the optimization. Four key points are then discussed in turn: (i) which features are necessary to be accounted for in constitutive modelling of sand; (ii) which type of tests (drained and/or undrained) should be selected for an optimal identification of parameters; (iii) what is the minimum number of tests that should be selected for parameter identification; and (iv) what is the suitable and least strain level of objective tests to obtain reliable and reasonable parameters. Finally, a useful guide, based on all comparisons, is provided at the end of the discussion. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Genealogy of hypoplasticity and barodesy          下载免费PDF全文

Dimitrios Kolymbas  Gertraud Medicus 《国际地质力学数值与分析法杂志》2016,40(18):2532-2550

This article is an attempt at providing an insight into the development of hypoplasticity (including barodesy, which is a recent development of hypoplasticity) as a theory elaborated since 1977, when the first version was published by the first author, until present. The multiplicity of the many versions published since then is hard to overlook. This article presents a review and insight into the evolution of a theory and the struggle to formulate a satisfactory constitutive law. Among the many proposed versions, we focus on those ones that can be seen as changes of paradigm. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Explicit stress–strain equations for modeling frictional materials     

Kenneth J. Xu  Martin D. Liu  Buddhima Indraratna 《Marine Georesources & Geotechnology》2018,36(6):722-734

In this paper, a comprehensive study on simulating the shearing behavior of frictional materials is performed. A set of two explicit equations, describing the relationship among the shear stress ratio and the distortional strain and the volumetric strain, are formulated independently. The equations contain three stress parameters and three strain parameters and another parameter representing the nonuniformity of stress and strain during softening. All the parameters have clear physical significance and can be determined experimentally. It is demonstrated that the proposed equations have the capacity of simulating the complicated shearing behavior of many types of frictional materials including geomaterials. The proposed equations are used to simulate the stress–strain behavior for 27 frictional materials with 98 tests. These materials include soft and stiff clays in both reconstituted and structured states, silicon sands and calcareous sands, silts, compacted fill materials, volcanic soils, decomposed granite soils, cemented soils (both artificially and naturally cemented), partially saturated soils, ballast, rocks, reinforced soils, tire chips, sugar, wheat, and rapeseed. It has been demonstrated that the proposed explicit constitutive equations have the capacity to capture accurately the shearing behavior of frictional materials both qualitatively and quantitatively. A study on model parameters has been performed.  相似文献