基于PCA-TOPSIS的重庆市县域经济密度综合测度及时空演变          下载免费PDF全文

张彬  谢贤健  杨联安  郭金铭 《干旱区地理》2020,43(2):546-556

经济密度是衡量区域经济发展水平和聚集程度的重要指标之一。以重庆市38个县（区）所辖范围为研究区，建立了人均和地均相结合的综合测度指标体系，采用主成分分析确定指标权重，将PCA TOPSIS评价法运用到经济密度综合测度中，依据测度对象与最优值的相对接近程度，综合测度1997年、2001年、2006年和2013年重庆市县域经济密度，获得各个时间断面经济密度综合指数及其排名。通过利用ArcGIS制图功能绘制重庆市经济密度等级分布图，揭示其空间分异演变规律，利用Moran’s I，LISA和热点分析分别探索了县域经济密度的全局和局部空间自相关及其时空演变规律，并讨论影响经济密度高低的主要因素。通过对县域经济密度的综合测度及时空演变的探究，为实现城市科学定位和制定中长期发展战略提供科学依据。  相似文献   

毛乌素沙地东南缘全新世气候不稳定性     

李想  苏志珠  马义娟  张彩霞  柳苗苗 《中国沙漠》2020,40(2):109-117

毛乌素沙地处于中国季风区的西北边缘,对气候变化敏感,是古气候演化和古环境变迁研究的理想场所。全新世气温回暖期,气候整体稳定但存在暖湿冷干的次级波动,不同类型沉积相组成的地层序列记录了全新世千年、百年尺度的气候不稳定性。对毛乌素沙地不同沉积序列的研究表明:(1)毛乌素沙地东南缘的沙漠/黄土边界带DLT、NB剖面粒度及Rb/Sr比值可作为气候变化的代用指标。>63 μm砂含量增加,Rb/Sr比值降低,揭示东亚冬季风增强,风成砂堆积,风沙活动加剧,气候干冷;反之,东亚夏季风增强,降水增多,风化成壤程度加大,气候暖湿。(2)毛乌素沙地东南缘沙漠/黄土边界带及低洼沟谷区年代概率密度函数的分析显示,全新世早期~8\^5 ka BP风成砂堆积,风沙活动加剧,气候表现为干冷;全新世中期8\^5 ka~3\^0 ka BP地势较高处古土壤广泛发育,地势低洼处发育湖沼相/泥炭层,但在6.0 ka BP左右存在气候转冷过程;全新世晚期3\^0 ka BP以来气候波动频繁。(3)毛乌素沙地气候变化与北大西洋冰筏冷事件、董哥洞石笋、季风边缘区湖泊、东部沙地等记录具有可对比性和相对一致性,反映出全新世千年和百年尺度上的气候变化主要受全球变化的影响,这对预测和模拟未来气候变化具有借鉴意义。  相似文献   

物化探综合信息找矿方法在萤石矿找矿中的应用     

栗克坤  陈新立  商朋强  于雪良  韩志坤  魏凡超  刘增政 《中国地质调查》2019,6(6):98-104

福建光泽地区是闽北地区重要的萤石矿成矿远景区,具有寻找隐伏—半隐伏萤石矿的潜力,但是目前该区隐伏—半隐伏萤石矿找矿成果较少。通过对福建光泽地区I号萤石矿预测区开展物化探综合信息找矿方法应用,探讨物化探综合信息找矿方法在隐伏—半隐伏萤石矿找矿中的应用效果。结果表明: 区域水系沉积物测量和大比例尺化探剖面测量圈出的F、Ca等综合异常信息可协助筛选、确定萤石矿找矿目标区; 将高精度磁法测量与视电阻率联合剖面测量相结合,可进一步判断萤石矿控矿构造的位置和规模; 高密度电阻率法测量可协助确定控矿构造的深部延伸情况。地表检查和深部钻探验证表明: 区域化探、高精度磁法测量、视电阻率联合剖面测量和高密度电阻率法测量等物化探综合信息找矿方法组合,可指导隐伏—半隐伏萤石矿的找矿工作。  相似文献   

基于局部倾斜叠加的快速射线束叠前时间偏移          下载免费PDF全文

陈祥忠  岳玉波  王瑞兴  刘俊成  惠梦琳 《地球物理学报》2020,63(4):1585-1590

宽方位高密度地震勘探可以有效的提高地震资料的空间分辨率和裂缝预测的精度,但地震道数的增加也大幅度提升了地震数据的处理成本.为提高海量地震数据偏移处理的计算效率,本文发展了一种快速射线束叠前时间偏移方法.该方法首先根据给定的射线束中心间隔将炮记录划分为一系列数据子集,然后利用倾斜叠加将数据子集分解为不同方向的平面波,最后根据射线束中心到地下成像点的双程走时和射线参数拾取相应的平面波振幅累加到成像点上.同Kirchhoff叠前时间偏移相比,本文方法不但保持了一致的成像精度,且由于仅需在稀疏的射线束中心位置进行成像累加运算,计算效率得到了大幅度的提升.文中所给出的模型和实际资料的测试结果验证了本文方法的正确性和有效性.  相似文献   

Density effects on solute release from streambeds     

Guangqiu Jin  Wenhai Yang  Huiyu Xu  Zhongtian Zhang  Saiyu Yuan  Hongwu Tang  Ling Li  David Andrew Barry 《水文研究》2020,34(5):1144-1153

Contaminants that entered the streambed during previous surface water pollution events can be released to the stream, causing secondary pollution of the stream and impacting its eco-environmental condition. By means of laboratory experiments and numerical simulations, we investigated density effects on the release of solute from periodic bedforms. The results show that solute release from the upper streambed is driven by bedform-induced convection, and that density effects generally inhibit the solute release from the lower streambed. Density gradients modify the pore water flow patterns and form circulating flows in the area of lower streambed. The formation of circulating flows is affected by density gradients associated with the solute concentration and horizontal pressure gradients induced by stream slope. The circulating flows near the bottom of the streambed enhance mixing of the hyporheic zone and the ambient flow zone.  相似文献   

Intercomparison of measurements of bulk snow density and water equivalent of snow cover with snow core samplers: Instrumental bias and variability induced by observers     

J. Ignacio López-Moreno  Leena Leppänen  Bartłomiej Luks  Ladislav Holko  Ghislain Picard  Alba Sanmiguel-Vallelado  Esteban Alonso-González  David C. Finger  Ali N. Arslan  Katalin Gillemot  Aynur Sensoy  Arda Sorman  M. Cansaran Ertaş  Steven R. Fassnacht  Charles Fierz  Christoph Marty 《水文研究》2020,34(14):3120-3133

Manually collected snow data are often considered as ground truth for many applications such as climatological or hydrological studies. However, there are many sources of uncertainty that are not quantified in detail. For the determination of water equivalent of snow cover (SWE), different snow core samplers and scales are used, but they are all based on the same measurement principle. We conducted two field campaigns with 9 samplers commonly used in observational measurements and research in Europe and northern America to better quantify uncertainties when measuring depth, density and SWE with core samplers. During the first campaign, as a first approach to distinguish snow variability measured at the plot and at the point scale, repeated measurements were taken along two 20 m long snow pits. The results revealed a much higher variability of SWE at the plot scale (resulting from both natural variability and instrumental bias) compared to repeated measurements at the same spot (resulting mostly from error induced by observers or very small scale variability of snow depth). The exceptionally homogeneous snowpack found in the second campaign permitted to almost neglect the natural variability of the snowpack properties and focus on the separation between instrumental bias and error induced by observers. Reported uncertainties refer to a shallow, homogeneous tundra-taiga snowpack less than 1 m deep (loose, mostly recrystallised snow and no wind impact). Under such measurement conditions, the uncertainty in bulk snow density estimation is about 5% for an individual instrument and is close to 10% among different instruments. Results confirmed that instrumental bias exceeded both the natural variability and the error induced by observers, even in the case when observers were not familiar with a given snow core sampler.  相似文献   

曲靖非相干散射雷达电离层F区日间电子温度变化特征初步分析   总被引：1，自引：0，他引：1       下载免费PDF全文

丁宗华  代连东  杨嵩  唐志美  吴健  许正文 《地球物理学报》2020,63(4):1282-1293

利用曲靖非相干散射雷达2017-2018年春夏季观测数据首次分析了电离层日间150~450km电子温度的地方时与高度变化特征及其与电子密度的相关性.发现hmF2及以上的电子温度在日出日落时具有两个峰值,在11∶00-16∶00LT之间变化较小,高度越高午后上升的时间越早;从150km开始迅速增加,在约220km达到最大值,然后开始降低,在约300~350km达到最小值,最后单调上升;200km以下电子温度与电子密度成正相关(主要由热传导控制),200~450km之间存在明显的反相关(光电离过程占主导),电子-离子温度差与电子密度对数之间存在近似线性关系,电子温度逐日变化与光电离因子的变化趋势相似,这种相关性在中午与午后更明显;以上结果与其他非相干散射雷达观测和电离层模型计算结果基本一致,但也存在一些差别,需要结合更多数据深入分析.  相似文献   

Effects of rainfall intensity and compaction on water transport from opencast coal mine soils: An experimental study     

Fengjiao Wang  Jinman Wang 《水文研究》2020,34(2):258-269

The use of heavy machinery during opencast coal mining can result in soil compaction. Severe soil compaction has a negative impact on the transport of water and gas in the soil. In addition, rainfall intensity has traditionally been related to soil surface sealing affecting water transport. To assess the effects of rainfall intensity and compaction on water infiltration and surface runoff in an opencast coal mining area, the disturbed soils from the Antaibao opencast mine in Shanxi Province, China, were collected. Four soil columns with different bulk densities (i.e., 1.4 g cm^-3, 1.5 g cm^-3, 1.6 g cm^-3, and 1.7 g cm^-3) were designed, and each column received water five times at rainfall intensities of 23.12, 28.91, 38.54, 57.81, and 115.62 mm hr^-1. The total volume of runoff, the time to start runoff, and the volumetric water contents at the depths of 5 cm, 15 cm, 25 cm, 35 cm, 45 cm, 55 cm, and 65 cm were measured. Under the same soil bulk density, high rainfall intensity reduced infiltration, increased surface runoff, and decreased the magnitude of change in the volumetric water contents at different depths. Under the same rainfall intensity, the soil column with a high bulk density showed relatively low water infiltration. Treatments 3 (1.6 g cm^-3) and 4 (1.7 g cm^-3) had very small changes in volumetric water contents of the profiles even under a lower rainfall intensity. Severe soil compaction was highly prone to surface runoff after rainfall. Engineering and revegetation measures are available to improve compacted soil quality in dumps. Our results provide a theoretical basis for the management of land reclamation in opencast coal mine areas.  相似文献   

路网约束条件下热力规则设计与试验     

杜晓  周玉秀  周琦  郑义  张俊辉  林尚纬  陈利军 《测绘通报》2020,(7):18-21

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   

重庆市中梁山地区隐伏塌陷特征及物探勘测的思路     

张银松  曹聪  康世海  刘家富 《中国岩溶》2020,39(6):918-927

为查明隐伏塌陷区域，分析重庆市中梁山地区岩溶塌陷的特征，发现塌陷主要发生在以岩溶裂隙发育为主的松散粉质黏土区域；地震映像法能方便、快速地查清土层的松散状态，而高密度电阻率法通过正演模拟发现只能探测出2～3倍电极距的异常范围，但能反映出岩溶裂隙发育的漏斗形态，即只要能找出岩溶裂隙的大致位置和浅表松散土层的范围就能圈定隐伏塌陷的区域。对中梁山地区某居民点进行野外勘测，综合以上两种方法圈定隐伏塌陷区域，其推断结果与钻探资料十分吻合，说明这种隐伏岩溶探测思路是可行的。   相似文献