基于路划网络功能的道路选取方法

提出以路划为选取单元以路划网络功能为选取指标的道路选取方法,路划网络功能的衡量指标综合考虑了中心度、连接度、长度等因素,由网络分析获得;选取的道路通过基于图论的逐步搜索保持连通性和规模最小;采用多种结构形态的实际城市局部路网、整体路网进行试验,结果表明该方法能较好地保持路网的整体结构、局部典型结构和道路连贯性,适用于各种形态的路网,具有良好的通用性,较常规的基于路划长度的选取方法具有明显优势。     

农村抽样调查三维空间化样本抽选与管理系统实现

本文讨论了目前国家农村统计业务中迫切需求的技术,并详细介绍了通过GIS/RS技术和传统统计抽样方法的结合,集成农村抽样调查空间化样本抽选与总体推断,设计并实现了集"4D"海量数据为一体的二三维联动农村抽样调查空间化样本抽选与管理系统,为全国的农村抽样调查统计业务提供参考。     

SPOT-5影像融合技术在西部测图工程中的应用

本文针对西部干燥荒漠地区的地貌地表影像,进行了基于信息量的波段选取和融合试验,获取了一定的经验值,将此经验值应用于相似类型地表的影像融合后,取得了良好的效果。经实际生产作业证明,基于信息量理论选取的组合波段,能很好地保持原始影像的光谱特征,且融合后,影像层次丰富、色彩逼真。     

起算点对GPS控制网的影响及质量控制

针对GPS在山区石油地震勘探测量中的工作方式,结合2011年桂中地区2维地震资料采集项目和近几年物探测量项目应用GPS布设控制网的工程实例,分析起算点对GPS控制网平差结果的影响。从起算点的选取和分布、外业观测、基线处理到约束平差各个环节综合考虑,优选点位,合理设计,降低由于起算点的原因引起的误差,提高GPS控制网的质量。     

GIS环境下的物流配送中心选址模型研究

在分析传统的配送中心选址模型优缺点的基础上,提出了一种基于GIS的物流配送中心选址模型。该模型采用多因素参与决策的方法,结合GIS技术与空间分析方法确定最佳选址地点,最后以张家界市永定区某街道配送仓库的选址为例对模型进行了实现。     

鄂西生态文化旅游圈地图集选题研究

对于专题地图集而言,图集的内容和结构是决定图集质量的关键要素,也是抓住人们眼球的重点。《鄂西生态文化旅游圈地图集》(以下简称《鄂西圈图集》)不仅是跨行政区域的地图集,而且在内容上不同于一般意义上的综合性专题地图集,它以"生态、文化、旅游"专题为主要内容,这在全国范围内是少见的,具有一定的开创性。本文通过总结《鄂西生态文化旅游圈地图集》专题内容确定的过程和结果,阐述了编制图集过程中选题的重要性,需要与时俱进,抓住特色,突出重点,勇于创新。     

基于新型相似性测度的高光谱影像地物检测

提出了一种新型光谱相似性测度及其参数的自适应选择方法,并且将其应用到了高光谱影像地物检测中。由于这种相似性测度基于光谱角度余弦(SAC),因此在理论上对因光照强度变化、阴影和遮挡等引起的同种地物光谱变化的适应性较强。最后利用两幅高光谱影像进行了实验分析,实验结果证明提出的方法不仅能扩大阈值取值区间,而且可提高检测的精度。     

模态静力非线性分析中模态选择的研究

本文应用模态静力非线性分析方法,对多个算例进行了静力非线性分析。比较分析了不同振型组合对计算精度的影响,对模态选择的参数进行了研究,提出采用模态质量参与系数进行模态选择的控制,为模态静力非线性分析方法的推广使用提供参考。另外,分析了结构基本周期对该方法计算精度的影响。     

Quickflow response to forest harvesting and recovery in a northern hardwood forest landscape

Forest harvesting often increases catchment quickflow (QF, water delivered rapidly to the stream channel), a metric of high‐flow events controlling a catchment's solute and sediment export. Nevertheless, our understanding of QF responses to various silvicultural strategies (e.g., clearcutting, selection harvest, and shelterwood harvest) is incomplete. We present a 31‐year examination of QF delivery from treatment (clearcut, selection harvest, and shelterwood harvest) and control catchments in a deciduous forest landscape in central Ontario, Canada. Growing season root‐zone storage capacity was estimated using a water balance approach to evaluate temporal changes in QF response to precipitation (P) for pretreatment and posttreatment periods. Threshold relationships between QF and P were assessed for control and treatment catchments for pretreatment and posttreatment periods using piecewise regression. Root‐zone storage capacity demarcated shifts in the hydrologic regime arising from forest harvesting and subsequent regeneration. This was particularly pronounced for clearcutting where postharvest decline in root‐zone storage capacity was followed by a rise to preharvest values. Similar pretreatment threshold relationships between QF and P, and near‐identical P thresholds for producing significant QF, reflected similar soil and overburden depths in the catchments. Harvesting effects were indicated by increases in QF/P ratios for relative small P and the number of P events that generated QF, thus changing treatment QF vs. P threshold relationships. Prior to harvesting there was no significant increase in QF with P below a threshold P of 35–45 mm; however, there was a significant QF vs. P relationship below this threshold for all treatments postharvest. Clearcutting increased the number of QF events for the entire postharvest period and the first 9‐year postharvest compared to the other treatments; nevertheless, evidence for intertreatment differences in total QF depth delivered from the catchments during the growing season was inconclusive. Our work suggests that changes in threshold relationships between QF and P, coupled with knowledge of the physical processes underlying them, are useful when evaluating hydrologic responses to forest harvesting.     

Amount and reactivity of dissolved organic matter export are affected by land cover change from old-growth to second-growth forests in headwater ecosystems

Headwater forest ecosystems of the western USA generate a large portion of the dissolved organic matter (DOM) transported in streams across North America. Land cover changes that alter forest structure and species composition affect the quantity and composition of DOM transferred to aquatic ecosystems. Clear-cut harvesting affects ~1% of the forest area of North America annually, leaving most western forests in varying stages of regrowth and the total area of old-growth forest is decreasing. The consequences of this widespread management practice on watershed carbon cycling remain unknown. We investigated the role of land cover change, because of clear-cut harvesting, from mixed-species old-growth to lodgepole pine-dominated second-growth forest on the character and reactivity of hillslope DOM exports. We evaluated inputs of DOM from litter leachates and export of DOM collected at the base of trenched hillslopes during a 3-year period (2016–2018) at the Fraser Experimental Forest in north-central Colorado, USA. Dissolved organic carbon and total dissolved nitrogen were higher in lateral subsurface flow draining old- versus second-growth forest. Fluorescence spectroscopy showed that the DOM exported from the old-growth forest was more heterogeneous and aromatic and that proteinaceous, microbially processed DOM components were more prevalent in the second-growth forest. Biological oxygen demand assays revealed much lower microbial metabolism of DOM in litter leachate and subsurface exports from the old-growth forest relative to second growth. Old-growth and second-growth forests are co-mingled in managed ecosystems, and our findings demonstrate that land cover change from a mixture of conifer species to lodgepole pine dominance influences DOM inputs that can increase the reactivity of DOM transferred from terrestrial to aquatic ecosystems.