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DEM Fusion using a modified k-means clustering algorithm

International Journal of Digital Earth 2016年第12期9卷 1242-1255页

作者： Colleen E.Fuss aaron a.berg John B.Lindsay Department of Geography University of GuelphGuelphCanada

Digital elevation models(DEMs)are a necessary dataset for modelling the Earth’s surface;however,all DEMs contain *** can reduce this error using DEM fusion techniques since numerous DEMs can be available for a ***,the use of a clustering algorithm in DEM fusion has not been previously *** this study a new DEM fusion algorithm based on a clustering approach that works on multiple DEMs to exploit consistency in the estimates as indicators of accuracy and precision is *** fusion approach includes slope and elevation thresholding,k-means clustering of the elevation estimates at each cell location,as well as filtering and smoothing of the fusion *** of the input DEMs,and the products of each step of the fusion algorithm,with a higher accuracy reference DEM enabled a detailed analysis of the effectiveness of the DEM fusion *** main findings of the research were:the k-means clustering of the elevations reduced the precision which also impacted the overall accuracy of the estimates;the number of final cluster members and the standard deviation of elevations before clustering both had a strong relationship to the error in the k-means estimates.

关键词： DEM fusion k-means clustering DEM error

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Determining minimum sample size for the conditioned Latin hypercube sampling algorithm

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Pedosphere 2024年第3期34卷 530-539页

作者： Daniel D.SAURETTE Asim BISWAS Richard J.HECK Adam W.GILLESPIE aaron a.berg School of Environmental Sciences University of Guelph50 Stone Rd EastGuelph ON N1G 2W1(Canada) Ontario Ministry of Agriculture Food and Rural Affairs1 Stone Rd WestGuelph ON N1G 2Y4(Canada) Geography Environment&GeomaticsUniversity of Guelph50 Stone Rd EastGuelph ON N1G 2W1(Canada)

In digital soil mapping(DSM),a fundamental assumption is that the spatial variability of the target variable can be explained by the predictors or environmental *** to adequately sample the predictors have been well documented,with the conditioned Latin hypercube sampling(cLHS)algorithm receiving the most attention in the DSM *** advances in sampling design,a critical gap remains in determining the number of samples required for DSM *** propose a simple workflow and function coded in R language to determine the minimum sample size for the cLHS algorithm based on histograms of the predictor variables using the Freedman-Diaconis rule for determining optimal bin *** preprocessing was included to correct for multimodal and non-normally distributed data,as these can affect sample size determination from the *** on a user-selected quantile range(QR)for the sample plan,the densities of the histogram bins at the upper and lower bounds of the QR were used as a scaling factor to determine minimum sample *** technique was applied to a field-scale set of environmental covariates for a well-sampled agricultural study site near Guelph,Ontario,Canada,and tested across a range of *** results showed increasing minimum sample size with an increase in the QR *** sample size increased from 44 to 83 when the QR increased from 50% to 95% and then increased exponentially to 194 for the 99%*** technique provides an estimate of minimum sample size that can be used as an input to the cLHS algorithm.

关键词： bin width digital soil mapping normal distribution quantile range sampling design

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A comparison of three surface roughness characterization techniques:photogrammetry,pin profiler,and smartphone-based LiDAR

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International Journal of Digital Earth 2022年第1期15卷 2422-2439页

作者： Zohreh Alijani Julien Meloche Alexander McLaren John Lindsay Alexandre Roy aaron berg Department of Geography Environment and GeomaticsUniversity of GuelphGuelphCanada Département de Géomatique Appliquée Université de SherbrookeSherbrookeCanada Département des Sciences de l’Environment Université du Québec à Trois-RivièresTrois-RivièresCanada

Surface roughness plays an important role in microwave remote *** the agricultural domain,surface roughness is crucial for soil moisture retrieval methods that use electromagnetic surface scattering or microwave radiative transfer ***,improved characterization of Soil Surface Roughness(SSR)is of considerable *** this study,three approaches,including a standard pin profiler,a LiDAR point cloud generated from an iPhone 12 Pro,and a Structure from Motion(SfM)photogrammetric point cloud,were applied over 24 surface profiles with different roughness variations to measure surface *** objective of this study was to evaluate the capability of smartphone-based LiDAR technology to measure surface roughness parameters and compare the results of this technique with the more common *** showed that the iPhone LiDAR technology,when point cloud data is captured in a fine-resolution mode,has a significant correlation with SfM photogrammetry(R2=0.70)and a relatively close agreement with pin profiler(R2=0.60).However,this accuracy tends to be greater for random surfaces and rough profiles with row structure *** results of this study confirm that smartphone-based LiDAR can be used as a cost-effective,fast,and time-efficient alternative tool for measuring surface roughness,especially for rough,wide,and inaccessible areas.

关键词： LiDAR surface roughness structure from motion iPhone pin profiler

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增加NanoLC-MS分析通量的柱切换纳喷雾源

增加NanoLC-MS分析通量的柱切换纳喷雾源

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中国化学会第二届全国质谱分析学术报告会

作者： Amanda.berg Helena Svobodova aaron Dewberry 王勇为 Gary Valaskovic New Objective Inc New Objective Shanghai

基于质谱的复杂蛋白组的分析前端色谱通常包括进样、洗脱、清洗三个基本步骤,由于使用纳升流速,上样时间和柱子准备时间随之增加,降低了有效采集数据的周期。自Nano LC-MS蛋白组流程建立以来,人们一直在寻求改善分析通量的方法。在过去... 详细信息

基于质谱的复杂蛋白组的分析前端色谱通常包括进样、洗脱、清洗三个基本步骤,由于使用纳升流速,上样时间和柱子准备时间随之增加,降低了有效采集数据的周期。自Nano LC-MS蛋白组流程建立以来,人们一直在寻求改善分析通量的方法。在过去十几年中纳喷源技术的发展,包括如纳喷雾数字化定位、源柱整合、柱加热和高清晰成像,特别是分离喷雾一体化和喷雾针的精确定位技术使得柱切换可以将传统的流路切换和空间位置切换相结合,大大简化了柱切换所需的复杂流路连接,从而提高了高通量分析的可靠性。本文介绍了一种新的多通道纳喷雾源整合技术,通过对多个平行排列的分离喷雾一体柱的自动控制,进行数字化喷雾柱位置切换,实现多通道并行Nano LC-MS分析功能。该方法的硬件配置为Eksigent三个单独的色谱纳微流泵和CTC自动进样器,其中两个为梯度泵,分别完成上样、洗脱和清洗。分析柱为New Objective的源柱一体Pico Chip柱,75um柱内径、10.5cm柱长和15um Tip。纳喷雾源为New Objective的Pico Slide多道线性柱切换纳喷雾源,在源上可放置预定位的三支分离喷雾柱和一支无填料空柱,空柱用于注射进样对质谱仪进行校准和调谐。柱流路切换由一个三位六通阀控制,通过Xcalibur的Contact closure控制。本方法采用的质谱仪为Thermo LTQ。Pico Slide多柱切换方法可使周期利用率达到近100%,在96小时内完成96次Hela蛋白组样品进样。和普通单柱相比分析周期提高1/3,增加近一倍样品分析数量或更多的有效色谱分离时间。对Hela蛋白组连续96次进样的重复性试验,证明了在同一支柱和不同柱间在保留时间和峰面积的重现性。同时,该方法可进一步发展为多维色谱方法。

关键词：柱切换位置切换纳喷雾源蛋白组分析通量

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