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101.
明晰城市热岛(UHI)效应相关概念内涵、厘清其定量刻画方法是有效开展UHI效应研究的重要基础。全球城市化进程使UHI效应越发普遍,相关研究数量迅速增长并出现了UHI效应的多样认知,尤其对具有空间异质性表征优势的地表城市热岛(SUHI)效应开发了多样的定量刻画方法,但目前尚缺乏对其定量刻画方法的系统梳理。因此,本文对城市热岛、城市热岛效应、地表温度和城市热环境等易混淆概念进行了辨析,总结了各类UHI典型空间位置和尺度范围。在SUHI效应定量刻画中,将SUHI范围识别方法归结为城乡温度阈值、温度等级阈值、高斯拟合参数、温度衰减突变四大类,指出当前SUHI范围识别研究侧重于对SUHI影响规模的认知。研究同时对各类范围识别方法所对应的SUHI强度表征指标进行了梳理,认为理解指标本质内涵是掌握指标间潜在差异的前提。未来研究应整合多维度数据以突破单一SUHI监测途径,发展大尺度SUHI定量刻画方法以拓展定量研究的广度,认知连通化SUHI空间形态以挖掘范围识别研究的深度。 相似文献
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?о???????????RTK?ο???????????????????????????????????????????????????????????????????????????????????????????????????顣?????????÷??????????÷??????????????????????RTK???????????cm????λ?? 相似文献
104.
With the growing interest in studying characteristics of geographical context and its influence upon people, the concept of home range has been a focus of scholarly research. Home ranges are studied extensively across multiple disciplines, with literature supporting different operationalization techniques. This article argues that many of the existing approaches are not dynamic and versatile enough and do not provide reliable solutions for estimating individual home ranges. We additionally argue that many of current studies lack robust evaluation approaches. Recent evidences suggest that the usual approaches, which often exclusively rely on a single validation criterion, are not reliable and may be influenced by inferential errors. This study aims to tackle the exiting limitations in definition and operationalization of individual-based home range models and provide a more robust solution for their evaluation and comparison. Using data collected through public participation GIS we develop an applied, dynamic, and parametric model of individual home ranges. Subsequently, we propose multiple criteria comprising five validation hypotheses to evaluate model's effectiveness. We argue that application of this approach in evaluating spatial delimitation models can ameliorate the risk of biased validation resulting from inferential errors. The evaluation results indicate a substantial improvement in coverage of visited points compared to previously used static methods. Consequently, this paper draws a number of conclusions that can serve as guidelines for future research. This paper highlights the strengths and weaknesses of the proposed method and explains how it can be improved and employed in future studies investigating contextual effects on residents. 相似文献
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D. R. Engstrom C. Whitlock S. C. Fritz H. E. Wright Jr. 《Journal of Paleolimnology》1991,5(2):139-174
Recent sediments of eight small lakes in the northern winter range of Yellowstone National Park were cored to examine stratigraphic records of past changes in limnology and local environment that might be attributed to grazing and other activities of elk, bison, and other large ungulates. Cores of undisturbed sediment were analyzed at close intervals to depths covering the last 100–150 years according to chronologies established by lead-210 dating. Pollen analyses were made to show change in regional vegetation, and diatom and geochemical analyses were made to reveal possible limnological changes resulting from soil erosion and nutrient input from the lake catchments.Variations in sedimentary components prior to establishment of the Park in 1872 indicate some natural variability in environmental factors e.g., erosional inputs in landslide areas west of Gardiner. All lakes had abundant nutrient inputs.After the Park was founded, fire suppression may have been responsible for small increases in pollen percentages of various conifers and Artemisia tridentata (big sagebrush) at different times in different lakes. Perceptible decreases in pollen of willow, aspen, alder, and birch at different times may reflect local ungulate browsing, although drier climatic conditions may have been a factor as well.The most striking manifestation of accelerated erosion in a catchment was found at a lake located beside a road constructed in the 1930s. In contrast to changes at this site, the record of erosion at other lakes is hardly perceptible. Changes in sediment-accumulation rates seen at most sites result from redistribution of sediment within the lake after initial deposition.In the century following Park establishment, the abundance of planktonic diatoms relative to benthic taxa varies among lakes and may reflect differential nutrient inputs or changes in lake level. Four of the five lakes analyzed for diatoms show in the last few decades an increase in planktonic relative to benthic species, implying elevated nutrient inputs. The recent flora, however, is similar to that in pre-Park levels which suggests that these lakes have not been perturbed outside their normal range. Increased nutrient supply in recent decades for at least two of the lakes is supported by the geochemical data, which show an increase in biogenic silica and in organic matter.As a whole, our investigation of the sedimentary record does not support the hypothesis that ungulate grazing has had a strong direct or indirect effect on the vegetation and soil stability in the lake catchments or on the water quality of the lakes. 相似文献
107.
一种深度图像拟合圆柱的优化方法 总被引:1,自引:0,他引:1
圆柱状构件广泛存在于古建筑仿真中,为了提高古建筑深度图像圆柱拟合的精度,针对古建筑仿真3维建模的特点,提出基于高斯图获取圆柱拟合参数初始值,然后利用圆柱距离函数参数化法进行非线性最小二乘拟合的圆柱拟合方法.实验证明,该方法不仅具有较高的精度,而且拟合结果稳定可靠. 相似文献
108.
顾及大气延迟效应的YG-13A斜距标定 总被引:2,自引:1,他引:1
针对大气延迟时变误差影响遥感卫星十三号(YG-13A)斜距标定精度的问题,提出利用顾及大气延迟时变误差的斜距标定方法提高其斜距标定精度的策略。首先,利用基于NCEP气象资料和全球TEC数据的大气延迟改正方法来计算各标定景的大气延迟改正量。其次,将各标定景的大气延迟改正量代入斜距标定模型中。最后,在地面布设高精度角反射器控制点的情况下通过顾及大气延迟时变误差的斜距标定模型求解斜距测量系统误差,从而提高和验证斜距测量精度,角反射器控制点的平面和高程精度均优于0.1 m。利用嵩山遥感定标场地区的4组不同拍摄模式下获得的YG-13A卫星影像数据对比试验表明,相较于传统的斜距定标方法,在顾及大气延迟时变误差的情况下,4组数据的斜距改正值离散度均有所下降。利用太原、天津两个区域3景影像验证斜距改正后的精度,最小值为0.55 m,最大值为0.91 m,均值为0.70 m。试验结果证明了顾及大气延迟时变误差的斜距标定方法的有效性和可行性。 相似文献
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110.
基准站模糊度固定是网络RTK系统初始化的前提条件。文中使用非组合方法来固定基准站间模糊度。该方法相对于传统组合方法而言具有以下3个优点:1)基于非组合观测值,避免了观测噪声的放大;2)将L2模糊度变换为L1与宽巷模糊度WL(Wide-Lane)模糊度的差值,同步求解WL和L1模糊度浮点解,简化了计算过程;3)WL模糊度由平差得到,部分模糊度固定后,加快了其他WL模糊度的固定速度。实验结果表明,非组合方法相对于传统方法而言,WL模糊度固定速度提高了24.5%;L1模糊度固定正确率提高了7.9%。可以认为,在网络RTK初始化方面,非组合方法要优于传统方法。 相似文献