排序方式： 共有25条查询结果，搜索用时 31 毫秒
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糯扎渡水电站坝址区主要分布花岗岩,研究、认识花岗岩体工程地质特性,合理选择岩体物理力学参数,对大坝安全和经济十分重要.大量地质勘察及试验研究,对坝址区花岗岩体的成因、分布,及岩体质量等做出科学评价,提出合理且符合实际的力学参数指标建议值,为电站的建设提供了可靠的地质依据. 相似文献
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根据实时MICAPS资料,采用经验正交函数分解和滤波方法,统计分析了欧亚大陆上空700 hPa水汽输送通量流函数和势函数主要低频分量的分布特征。结果表明：存在流函数和势函数低频环流系统变化的关键区。根据关键区环流系统演变,确定了与上海地区未来10-30 d强降水过程相对应的预报指标。以上海地区2010年7月的降水过程预报为例概述了整个预报流程,并从物理机制上证明了低层（110°E,30°N）附近的辐合以及自低空至高空向东倾斜的上升运动是造成该次降水的主要成因。 相似文献
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晋宁磷矿表生改造型矿床及其判别标志 总被引：2，自引：0，他引：2
根据晋宁磷矿次生风化作用过程中磷块岩组成和结构的变化，归纳晋宁磷矿矿床特征及其影响因素，正确确定该矿风化矿石的判别指标。 相似文献
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Yaolin Liu Limin Jiao Yanfang Liu 《International Journal of Applied Earth Observation and Geoinformation》2011
The generalization index system is one of the critical issues for computer-aided land use database generalization. This paper studies the scale and land use pattern effects on land use database generalization indices and estimates the thresholds of these indices based on a typical land use database sample. The index system of land use database generalization is discussed and constructed from macro and micro perspectives. Six land use pattern metrics, namely, land use diversity index, land use dominance index, land use homogeneity index, land use fragmentation index, the index of land use type dominance, and the index of land use type fragmentation, are designed to characterize land use patterns and are introduced into the analysis of land use pattern effect on land use database indices. The analysis framework of the scale and land use pattern effects on the land use database indices are proposed by employing statistical techniques. Based on the land use database samples at multiple spatial scales collected in various land use regions across China, the study generates rules for both scale and land use pattern effects on the indices, including map area proportion of land use types, total map load, parcel map load, and minimum parcel area. The thresholds of these indices in land use database generalization are produced at the scales of 1:50,000, 1:100,000, 1:250,000, and 1:500,000. An experimental generalization at county level demonstrates how to determine the generalization index values considering scale and land use pattern, and how to evaluate the generalization results using our macro indices. 相似文献
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本文采用若干经济评价指标,初步建立了确定矿床经济合理勘探网度及最佳钻机台数的决策模型,且对某铁矿进行了实际应用。 相似文献
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用主成分分析方法通过计算机把雌性青蛤的软体部干重和3个生化指标综合为肥满指标和能源物质指标,从而允许用二维图象来显示。14个样品明显地分为碳水化合物为主要贮存能源物质和脂类、蛋白质为主要贮存能源物质两类。两个新指标的累积贡献率达94％。 相似文献
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利用中国691个无缺测站点的经均一化处理及质量控制的逐日最高、最低气温资料,基于冷昼日数、冷夜日数、霜冻日数、冰冻日数、月最低气温极大值以及月最低气温极小值等6个由世界气象组织定义的极端气温指数,分析了1961~2014年中国冬季的极端低温变化特征。结果表明:冷昼日数、冷夜日数、霜冻日数以及冰冻日数在全国大部分地区均呈现下降的趋势,下降趋势较为明显的区域集中在东北南部、华北、西北东部、华东、华中、西南及高原地区,全国整体上下降幅度分别为-0.9 d/10 a、-1.7 d/10 a、-1.5 d/10a和-1.4 d/10 a。最低气温极大值和最低气温极小值在全国范围内则主要呈现上升的趋势,全国整体上分别为0.4℃/10 a和0.6℃/10 a;极端低温天数在20世纪60年代至70年代中后期呈现波动状,随后自20世纪70年代末80年代初至21世纪初呈明显下降趋势,从2006年左右以后其下降趋势较之前有所减缓,是对全球变暖减缓背景下的气候响应;与其他时间段相比,20世纪60年代至70年代为冬季极端低温事件较为频发的时间段,这可能与该时段陆地冷高压频繁活动有关。 相似文献
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Hilary McMillan 《水文研究》2020,34(6):1393-1409
Hydrologic signatures are metrics that quantify aspects of streamflow response. Linking signatures to underlying processes enables multiple applications, such as selecting hydrologic model structure, analysing hydrologic change, making predictions in ungauged basins, and classifying watershed function. However, many lists of hydrologic signatures are not process-based, and knowledge about signature-process links has been scattered among studies from experimental watersheds and model selection experiments. This review brings together those studies to catalogue more than 50 signatures representing evapotranspiration, snow storage and melt, permafrost, infiltration excess, saturation excess, groundwater, baseflow, connectivity, channel processes, partitioning, and human alteration. The review shows substantial variability in the number, type, and timescale of signatures available to represent each process. Many signatures provide information about groundwater storage, partitioning, and connectivity, whereas snow processes and human alteration are underrepresented. More signatures are related to the seasonal scale than the event timescale, and land surface processes (ET, snow, and overland flow) have no signatures at the event scale. There are limitations in some signatures that test for occurrence but cannot quantify processes, or are related to multiple processes, making automated analysis more difficult. This review will be valuable as a reference for hydrologists seeking to use streamflow records to investigate a particular hydrologic process or to conduct large-sample analyses of patterns in hydrologic processes. 相似文献