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1.
热力图是一种能直观准确展示空间观测值的有效工具,在多个领域具有广泛应用。本文在分析设定不同道路层权重、道路技术等级分类的基础上,以反距离权重、直方图均衡化、密度补偿、参数多次迭代等方法,研究构建了以热力方式展示道路网分布及发达程度的相关规则体系。热力规则通过道路赋权、路线曲面化、密度协调、图面综合等多套规则的有机结合,实现了道路网总体发达水平信息的提取与展示,并以全球地理信息资源建设项目路网成果中的亚洲和非洲部分国家数据为例,进行了信息提取与热力分布试验。  相似文献   
2.
近年来国产卫星传感器类型日益丰富,使用自主可控的国产卫星影像进行生产和研究的需求越来越大,多源国产卫星影像联合平差的精度分析显得尤为重要。本文针对在立体测图生产中,资源三号卫星影像在时相较旧、噪声较大、云覆盖和摄影漏洞等特殊困难的条件下,利用天绘一号卫星影像进行补漏生产的情况,最终分析并验证了两者无控联合平差的可行性和成果精度。  相似文献   
3.
基于2012年6~8月的实测水汽同位素数据及相关气象数据,对黑河中游夏季昼夜的同位素基本特征、水汽来源方向及潜在蒸发源地进行了研究。结果表明:空气水汽线斜率白天大于夜晚和水汽过量氘值白天大于夜晚,综合说明白天局地蒸发较夜晚强烈;夏季受西风水汽影响显著。其中,6月主要受西风水汽和北冰洋水汽影响,7、8月主要受西风水汽和东南方向水汽影响,且8月受东南方向水汽影响最为明显;水汽运移路径上下垫面地形和气压带移动会影响水汽后向轨迹高度,西北方向上水汽输送通道较顺畅,风速较大,有利于水汽的输送;水汽蒸发源地主要集中在研究区周围及以东、以北部,其次是西北部。绿洲是主要的水汽蒸发源地,其次是城市和河流,白天较夜晚局地蒸发强烈且面积大。  相似文献   
4.
朱芳  苏勤  陶云  沈惊宏 《热带地理》2020,40(4):636-648
日常生活环境和旅游目的地环境都可以为个体提供恢复的机会,不同环境的属性特征导致不同程度的恢复。为了探究环境类型与恢复性效应之间的关系及停留时间的调节作用,文章采用问卷调查方式,利用配对样本t检验和混合设计方差分析相结合的方法,探讨游客在不同环境中的恢复性效应,并对这一现象提供心理上的解释。结果表明:1)恢复体验的4个维度(放松体验、心理脱离、掌握体验、控制体验)在旅游目的地环境中的得分均高于日常生活环境。2)掌握和控制体验维度在城市旅游目的地中的变化程度高于乡村旅游目的地,两种类型目的地的放松和心理脱离维度差异较小。3)随着在目的地停留时间的延长,乡村旅游目的地放松体验和心理脱离维度变化程度高于城市旅游目的地,两种类型目的地环境恢复性效应会相互靠近。因此,游客的环境恢复性效应不仅受到环境和目的地类型的影响,同时还与游客的适应程度有关,且受到其停留时间的调节作用。  相似文献   
5.
Three Super Active Regions in the Descending Phase of Solar Cycle 23   总被引:2,自引:0,他引:2  
We analyze the magnetic configurations of three super active regions, NOAA 10484, 10486 and 10488, observed by the Huairou Multi-Channel Solar Telescope (MCST) from 2003 October 18 to November 4. Many energetic phenomena, such as flares (including a X-28 flare) and coronal mass ejections (CMEs), occurred during this period. We think that strong shear and fast emergence of magnetic flux are the main causes of these events. The question is also of great interest why these dramatic eruptions occurred so close together in the descending phase of the solar cycle.  相似文献   
6.
本文讨论了彗星中尘埃粒子的充电机制 ,带电特性和平衡电势的变化规律 ,分析了彗星尘埃的破碎特性和临界半径 ,得出了很有意义的结果  相似文献   
7.

Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy covariance technology was applied to investigate the long-term carbon exchange over a 200 year-old Chinese broad-leaved Korean pine mixed forest in the Changbai Mountains (128°28′E and 42°24′N, Jilin Province, P. R. China) since August 2002. On the data obtained with open-path eddy covariance system and CO2 profile measurement system from Jan. 2003 to Dec. 2004, this paper reports (i) annual and seasonal variation of F NEE, F GPP and R E; (ii) regulation of environmental factors on phase and amplitude of ecosystem CO2 uptake and release Corrections due to storage and friction velocity were applied to the eddy carbon flux.

LAI and soil temperature determined the seasonal and annual dynamics of FGPP and RE separately. VPD and air temperature regulated ecosystem photosynthesis at finer scales in growing seasons. Water condition at the root zone exerted a significant influence on ecosystem maintenance carbon metabolism of this forest in winter.

The forest was a net sink of atmospheric CO2 and sequestered −449 g C·m−2 during the study period; −278 and −171 gC·m−2 for 2003 and 2004 respectively. F GPP and F RE over 2003 and 2004 were −1332, −1294 g C·m−2. and 1054, 1124 g C·m−2 respectively. This study shows that old-growth forest can be a strong net carbon sink of atmospheric CO2.

There was significant seasonal and annual variation in carbon metabolism. In winter, there was weak photosynthesis while the ecosystem emitted CO2. Carbon exchanges were active in spring and fall but contributed little to carbon sequestration on an annual scale. The summer is the most significant season as far as ecosystem carbon balance is concerned. The 90 days of summer contributed 66.9, 68.9% of F GPP, and 60.4, 62.1% of R E of the entire year.

  相似文献   
8.
Ground water contamination was discovered in 1981 in a monitoring well at the Earthline disposal facility near Wilsonville, Illinois. Organic chemicals had migrated at a rate 100 to 1000 times greater than predicted when the site received its permit to operate in 1978. Postulated failure mechanisms included migration through previously unmapped permeable zones, subsidence of an underground mine, organic-chemical and clay-mineral interactions, acid-mine drainage and clay interactions, trench-cover settlement, and erosion.
In this investigation, the Illinois State Geological Survey found the primary reason for the rapid migration: the presence of previously undetermined fractures and joints in glacial till. The inaccurate predictions of hydraulic conductivity were based on laboratory-determined values that did not adequately measure the effects of fractures and joints on the transit time calculations. Field-measured hydraulic conductivity values were generally 10 to 1000 times greater than their laboratory-measured counterparts, thus largely accounting for the discrepancy between predicted and actual migration rates in the transit time calculations. The problem was compounded, however, by the burial of liquid wastes and by trench covers that allowed excess surface runoff to enter the trenches. Organic-chemical and clay-mineral interactions may also have exacerbated the problem in areas where liquid organic wastes were buried.  相似文献   
9.
The concentrations of twenty four chemical elements in the surface layer of natural desert soils and the cultivated farmland soils were measured at a desert-oasis ecotone in the middle of Heihe river basin, north-west China. Background values were estimated for (a) major elements (Si 335.3 g kg− 1, Al 49.4 g kg− 1, Fe 19.1 g kg− 1, Ca 29.4 g kg− 1, Mg 8.9 g kg− 1, K 20.1 g kg− 1, Na 17.5 g kg− 1 and P 0.338 g kg− 1), (b) heavy metals and non-metals (Cr 55.8 mg kg− 1, Mn 404.8 mg kg− 1, Ni 17.7 mg kg− 1, Cu 5.1 mg kg− 1, Zn 33.7 mg kg− 1, Pb 15.5 mg kg− 1 and As 5.2 mg kg− 1) and (c) other trace elements (Ti 2.0 mg kg− 1, V 55.3 mg kg− 1, Co 5.7 mg kg− 1, Rb 82.4 mg kg− 1, Sr 232.9 mg kg− 1, Y 14.7 mg kg− 1, Zr 194.9 mg kg− 1, Nb 7.8 mg kg− 1 and Ba 720.6 mg kg− 1). After natural desert soil was cultivated for agricultural use, significant changes in element concentrations occurred under tillage, irrigation and fertilisation management. Compared to natural soil, the for the levels of Si, K, Na, Sr, Zr and Ba decreased, and no changes were observed for Rb, while the values of the other 17 elements increase in agricultural soil from 1.2 to 3.5 times. However, their absolute concentrations are still low, suggesting that the arable soil in this region remains comparatively a clean soil. The increased silt, clay and organic carbon content, under long-term irrigation, enriched the fine-grained materials, and application of fertilisers and manure contributed to the accumulation of most elements in arable soil. The accumulation of elements in agricultural soil increased with increasing cultivation years and extent of soil development.  相似文献   
10.
根据贵州普定陈旗堡典型喀斯特地区的生态特性,从水文地质与工程地质角度,借助土壤学对土壤水分特性的研究理论,对表层土壤20cm以下土层的土体物理化学性质与土体水分含量,即土体的持水量(waterholding capacity),进行了相关性研究。分析结果表明:土体颗粒成分、孔隙比、矿物成分含量等对土体水分含量均有影响。土体中粉粒含量较高而粘粒含量较少,且粒度分配不均匀时,土体水分含量相对较高;孔隙率高的土体水分含量较高;伊蒙混层矿物、伊利石和绿泥石等粘土矿物含量较高时,土体水分含量相对较高,而长石、碳酸盐等原生矿物含量较高时,土体水分含量相对较小。石英对于土体持水量影响不明显。  相似文献   
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