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空间数据挖掘技术研究进展 总被引:22,自引:0,他引:22
空间数据具有海量、非线性、多尺度、高维和模糊性等复杂性特点,空间数据挖掘技术是对空间数据中非显性的知识、空间关系等模式的自动提取。该文从空间数据挖掘的知识类型、方法、体系结构、过程以及与GIS系统集成等方面对其进行综述。重点阐述空间特征及区分规则、空间分类及聚类规则、空间分布及关联规则、空间序列及演化规则等知识类型以及统计分析、机器学习、探索性数据分析、可视化分析等数据挖掘方法。通过对空间数据挖掘理论、应用和系统实现等方面研究方向、存在问题的分析,指出集数据库、知识库、专家系统、决策支持系统、可视化工具、网络等技术于一体的空间数据挖掘系统是其主要发展方向。 相似文献
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青海季节冻土退化的成因及其对气候变化的响应 总被引:2,自引:1,他引:1
利用相关分析等数理统计学方法,分析了地形、气候等自然因子对季节冻土时空分布的影响,模拟了冻土对气温、降水、云量等气候因子变化的响应。研究表明:地形、气候因子对青海季节冻土的分布和演变有显著影响,气候变暖是造成季节冻土退化的主要原因;西宁城市化造成的"热岛效应"的加剧以及青海湖水位下降引起的"水体效应"的削弱等局地变化在某种程度上强化了季节冻土对气候变化的响应;季节冻土对气温变化的响应在旬、月尺度上较年际尺度上表现得更为明显,同时,随着冻土深度的加深其滞后效应越明显。 相似文献
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中国大学生的国际观调查分析 总被引:1,自引:0,他引:1
在经济全球化背景下,中国与其他国家在经济社会等方面的交流越来越多,并深刻影响了中国公众的国际观,但中国大学生对世界的看法尚缺乏系统研究。本文对北京、上海、南京、武汉和广州等5座城市的大学生进行抽样调查以了解其国际观,通过相关分析及绘制感知地图等方法,发现中国大学生有较强烈的国家归属感,对外部世界的偏好存在着较明显的空间特征,多数大学生对欧洲版图的划分比较正确。研究结果认为中国大学生国际观的形成主要受报纸网络电视等媒体的宣传和教科书等因素的影响。 相似文献
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马银行 《云南地理环境研究》2014,(4):56-62
地理探索与认识是古代人类扩大视野的重要途径。明朝在云南实施政治措施、军事行动、移民政策等,为明代士人对云南地理考察与记载提供基础。明代士人游历滇云写下大量的诗歌、游记、史志等,对云南地形地貌记在颇多,其中对滇东、滇西地表、地下岩溶地貌描述详实。明代士人依据云南岩溶地貌类型不同对其分类记载,并对岩溶地貌的形成原因初步探析。明人对溶洞的考察方法值得今人借鉴。旅游风气兴盛、政治措施得当、教育范围扩大、方志兴修等是明代云南岩溶地貌探索的重要原因。 相似文献
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分析1982—2019年中国核心学术刊物和著作,梳理地理学和政治学对于“地缘政治”概念和研究范式的不同理解。研究发现:① 地理学和政治学有很多相似之处,包括对“地缘战略”等概念的关注,对“大国安全与崛起”等议题的探讨,以及在分析框架中对案例和质性分析方法的强调等;② 地理学和政治学有各具特色,地理学衍生“地缘环境”等概念,政治学也衍生“地缘安全”等概念;地理学在议题上更具空间和系统思维,对海洋地缘政治等话题更偏好,而政治学更强调时事性,侧重于分析时事政治及其地缘政治逻辑等;在分析框架上,地理学受计量革命的影响深远,对质性和定量分析都有所关注,而政治学对案例分析和质性分析的依赖度更高。这些发现说明了当前学科分工并没有改变地理学中的“地缘政治”概念和政治学中的“地缘政治”概念源出一脉的事实,同时也发现,其中的差异正是学科壁垒形成关键所在。 相似文献
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省域城镇土地等别和基准地价快速更新方法研究——以江苏省为例 总被引:2,自引:0,他引:2
城镇土地等别和基准地价更新体系是对区域城镇地价水平进行平衡和宏观调控的重要手段.以江苏省为例,在综合分析原分等体系中"分等因素-分等因子-分等指标-等别指数"之间相关性及对应权重状况的基础上,得到全省城镇土地等别影响要素最小集及对应的权重集,据此构建省域城镇土地等别快速更新模型;然后,根据全省城镇土地分等指数与基准地价数据,建立了"基准地价-等别指数"耦合模型;最后对2个模型进行验证.结果表明,该方法对于江苏省省域土地等别和基准地价的快速更新具有较好的适用性,可为该省城镇土地等别和基准地价适势监测与调控提供技术支持. 相似文献
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根据农用地分等省级汇总的要求,提出了四种带有顺序性的分等单元制图综合方法,第一按地类、自然等、利用等、经济等相同合并邻接单元;第二在构建位于分等单元之外约束性Delauney 三角网的基础上,用边长作控制合并邻近地类、自然等、利用等、经济等相同的单元;第三删除零星单元,将面积归并到乡内地类、自然等、利用等、经济等相同的单元中;第四扩充零星单元.对提出的方法进行了编程实现,并在农用地分等省级汇总项目中得到了应用.理论分析及实验结果表明,所提方法具有严密的数学逻辑性,同时对地图制图综合这一前沿学术研究议题也具有一定借鉴与参考价值. 相似文献
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季节性河流是干旱区不同生态系间物种扩散交流的重要通道,也是维持干旱区生物多样性与生态系统稳定性的重要因子,但我国有关季节性河流水文生态学的研究一直相对滞后,且有关季节性河流水文长期动态的研究报道较少。以库姆塔格沙漠东南缘季节性河流-多坝沟为研究对象,利用自动水位计与人工调查相结合的方法,研究了洪沟内部的长期水文动态特征。研究显示:多坝沟洪水集中在6~9月份,降水是洪水的唯一驱动力。洪水频率、流量与降水季节、降水量、降水强度等因子密切相关。任何时间,单次降水量低于5 mm时,降水无法形成明显的洪水过程;春季单次降水低于16 mm或夏季单次降水低于10 mm时,最大洪水流量均不超过0.3 m3·s-1。在没有洪水发生时,春秋季节泉水径流量表现为陡涨缓落,而夏季呈现陡落缓涨。该研究不仅为干旱区季节性河流水文监测提供了可行有效的方法,同时为进一步研究库姆塔格沙漠周边的生态水文过程、水资源管理利用及植物生存演化提供了数据支撑。 相似文献
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西南岩溶山地生态环境研究进展与若干问题 总被引:5,自引:0,他引:5
李阳兵 《云南地理环境研究》2006,18(2):61-65
西南岩溶山地是典型的脆弱生态系统,是中国的关键生态区之一,石漠化逐步扩大等生态退化问题严重制约着该区持续发展,生态亟待恢复重建,但岩溶石漠化治理模式实际上受限于岩溶生态基础理论研究的不足。岩溶山地生态重建与可持续发展研究中应进一步加强地质地貌背景生态效应与生态类型划分问题、岩溶生态系统的恢复重建依赖对生态过程研究的突破、土地利用/土地覆盖的定量研究有待加强、治理模式的尺度性与转型研究,阐明岩溶生态系统的运行过程,提出石漠化类型划分和石漠化分级的科学依据。并通过生态系统评价和生态区评价,诊断存在问题,提出生态系统可持续管理的有效途径和方法。 相似文献
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An ecosystem approach for determining environmental water allocations in Australian dryland river systems: the role of geomorphology 总被引:3,自引:0,他引:3
The allocation of water for environmental purposes is a key management issue in many dryland regions. Many different methods have been developed for determining environmental water requirements but these are not directly applicable to dryland rivers because of inherent flow and habitat variability. An ecosystem approach for determining environmental water allocations in dryland regions is presented in this paper. This four-step process involves (1) a hierarchical characterisation of the river system, to assess what mesohabitats are present and where they are located; (2) the determination of flows that would inundate these habitats and perform other key ecological processes; (3) hydrological analyses in which the key hydrological signatures of the river are identified and the impact of water resource development on these is determined; and (4) the derivation of a water management decision tree that enables managers to allocate water to consumptive users during individual flood pulses (events). It is recommended that the flood pulse should be the focus for environmental flow management in dryland regions. If rivers are indeed nested hierarchies, then a change in hydrological behaviour at the scale of a flood pulse will, with time, extend throughout the hydrological hierarchy. Current environmental flow management strategies in dryland river systems are essentially focused at the flow regime and history scale; this is inappropriate given the inherent flow variability of these systems. The ecosystem approach is outlined for the Condamine-Balonne River, a large dryland system in Australia. 相似文献
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《Polar Science》2014,8(3):232-241
This study analyzes long-term (40–60 years) discharge and water temperature records collected near the basin outlets of the Yukon and Mackenzie Rivers. It defines seasonal cycles of discharge, water temperature (WT), and heat flux (HF) for the basins, and compares their main features to understand their similarity and difference. Both rivers have similar hydrographs, i.e. low flows in winter and high discharge in summer, with the peak flood in June due to snowmelt runoff. Mackenzie River has many large lakes and they sustain the higher base flows over the fall/winter season. Mackenzie basin is large with high precipitation, thus producing 50% more discharge than the Yukon River to the Arctic Ocean. The WT regimes are also similar between the two rivers. Yukon River WT is about 2–3 °C warmer than the Mackenzie over the open water months. Both rivers have the highest WT in the mid summer and they transport large amount of heat to the polar ocean system. Yukon River monthly HF is lower by 10–60% than the Mackenzie mainly due to smaller discharge. Mackenzie River heat transport peaks in July, while the Yukon HF reaches the maximum in June and July. These results provide critical knowledge of river thermal condition and energy transport to the northern seas. They are useful for large-scale climate and ocean model development and validation, and climate/hydrology change research in the northern regions. 相似文献
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半干旱地区地表水平衡的特征和模拟 总被引:13,自引:1,他引:12
作者分析了我国半干旱区草原典型地区的水量平衡的特点。由于地处东亚季风区和西风带的过渡带,降水主要集中在夏季,且多短时间对流性降水,其中绝大部分消耗于蒸发,地表径流很少,土壤比较干燥。冬季积雪, 春季融雪集中,能产生较强的径流,这与夏季降水形成的径流构成双峰型特征,在我国半干旱区较为典型。由于这些特点,在地表水量平衡的计算和模拟中,蒸发的估算十分重要,为此在植被-大气相互作用模式 (AVIM) 中对水文过程作了改进,模式中包含了大气-植被-土壤间的能量和水分传输过程,特别是半干旱区地表蒸发和植被的蒸腾过程作了比较细致的处理,考虑了蓄满和超渗两种产流机制,同时采用了一个简化的雪盖模型。以此模型模拟了内蒙古半干旱草原上锡林河流域的地表水文过程。计算结果显示,半干旱区地表水平衡,蒸发大而径流小及产流的春夏双峰型特征都能很好地模拟。这些过程的参数化方案也适用于非干旱区。 相似文献
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新疆水文水资源变化及对区域气候变化的响应 总被引:6,自引:1,他引:5
Based on the surface runoff, temperature and precipitation data over the last 50 years from eight representative rivers in
Xinjiang, using Mann-Kendall trend and jump detection method, the paper investigated the long-term trend and jump point of
time series, the surface runoff, mean annual temperature and annual precipitation. Meanwhile, the paper analyzed the relationship
between runoff and temperature and precipitation, and the flood frequency and peak flow. Results showed that climate of all
parts of Xinjiang conformably has experienced an increase in temperature and precipitation since the mid-1980s. Northern Xinjiang
was the area that changed most significantly followed by southern and eastern Xinjiang. Affected by temperature and precipitation
variation, river runoff had changed both inter-annually and intra-annually. The surface runoff of most rivers has increased
significantly since the early 1990s, and some of them have even witnessed the earlier spring floods, later summer floods and
increasing flood peaks. The variation characteristics were closely related with the replenishment types of rivers. Flood frequency
and peak flow increased all over Xinjiang. Climate warming has had an effect on the regional hydrological cycle. 相似文献
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T.A. McMahon R.E. Murphy M.C. Peel J.F. Costelloe F.H.S. Chiew 《Journal of Arid Environments》2008,72(10):1869-1886
This is the second of two papers examining the surface hydrology of the Lake Eyre Basin (LEB) (1,140,000 km2) in Australia. The streams are unregulated and are characterised by extreme discharge variation. The analyses reported cover only surface hydrology and include comparisons with arid zone catchments globally. The paper discusses spatial runoff and annual streamflow characteristics, flow duration and baseflow index (BFI) analyses, annual flood frequency analysis and flood transmission losses, a water balance study, wet and dry run length analysis and, finally, yield from hypothetical reservoirs located across the LEB. There are 12 conclusions listed at the end of the paper. We identify two highlights as follows:
- • The coefficient of variation of annual flows, Cv, varies from 0.98 to 2.62. Compared with 45 arid zone rivers world-wide excluding Australian rivers, the annual Cv of the LEB streams are approximately double the average variability found world-wide.
- • Large transmission losses occur as flood flows move down the middle reaches of the major river systems. The transmission losses vary non-linearly with flood size as a result of differing transmission efficiencies between primary channels and the floodplain, and varying floodplain utilisation.
Keywords: Hydrology; Lake Eyre; Runoff; Surface hydrology; Yield 相似文献
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Local Modeling模式及其在月径流预测中的应用 总被引:5,自引:2,他引:5
Local Modeling方法是一种动力系统预测方法,将其应用于河西内陆区黑河干流出山口莺落峡水文站月平均流量的中长期预测预报,取得了较为理想的成果。预测试验的结果表明,该预测模型有较高计算精度,尤其适用于非主汛期各月的月平均流量的预测;对于主汛期6~9月的月平均流量的预测,在考虑前期来水与预见期内降水的影响后,亦可获到较为理想的预测结果。可以认为,该方法的预报精度达到了水文情报预报规范的要求,Local Modeling方法的应用,将为西北干旱地区河川径流的中长期预报提供了一个新的途径。 相似文献