共查询到20条相似文献，搜索用时 25 毫秒
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Application of developed Grid-GA distributed hydrologic model in semi-humid and semi-arid basin 总被引：1，自引：0，他引：1
A grid and Green-Ampt based(Grid-GA)distributed hydrologic physical model was developed for flood simulation and forecasting in semi-humid and semi-arid basin. Based on topographical information of each grid cell extracted from the digital elevation model (DEM) and Green-Ampt infiltration method, the Grid-GA model takes into consideration the redistribution of water content, and consists of vegetation and root interception, evapotranspiration, runoff generation via the excess infiltration mechanism, runoff concentration, and flow routing. The downslope redistribution of soil moisture is explicitly calculated on a grid basis, and water exchange among grids within runoff routing along the river drainage networks is taken into consideration. The proposed model and Xin’anjiang model were applied to the upper Lushi basin in the Luohe River, a tributary of the Yellow River, with an area of 4 716 km2 for flood simulation. Results show that both models perform well in flood simulation and can be used for flood forecasting in semi-humid and semi-arid region. 相似文献
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孙艳玲 《重庆大学学报(英文版)》2005,4(1):38-40
1 Introduction1 Drainage network is of wide application in hydrological and geomorphological studies. It can be used for not only rainfall-runoff simulations on the watershed but also simulations of the transport of non-point source pollutants. Drainage network composition data can be used for geomorphologic evaluations [1]. Digital Elevation Model (DEM) is digital records of terrain elevations for ground positions, and is also the main data for watershed analyses, which usually has three fo… 相似文献
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为了获得现场实测和风洞实验中测点较为稀疏地区的风压系数,以及弥补"坏点"造成的数据缺失问题,引入地理信息系统中有关数字高程模型的理念.以某单坡屋面为例,将实测结果进行网格化处理,并用风压系数代替高程数值,利用多种类型的插值方式获取待估位置的风压系数,最后分析对比不同方法的计算精度.结果表明克里格方法效果最好. 相似文献
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平原地区的河网提取一直是基于数字高程模型(DEM)的水系提取的难点。尝试利用主干河流修正不规则三角网(TIN),以提高DEM平原地区地形模拟的精度(基本方法为利用已存在的主干河流线,对其所经区域进行高程赋值,约束TIN的构建,然后进行DEM模拟),基于此进行平原区河网提取。实验表明,此种方法下,平原区提取的主干河流与实际河流有较大的吻合。 相似文献
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姚艺贤刘德标陈津邓历振洪晋伟刘智才 《福建工程学院学报》2021,(1):95-102
以Landsat8OLI/TIRS遥感影像和DEM高程数据为数据源,以福建三明境内的莆炎高速公路YA12标段两侧1000m路域范围为研究区域,对南方红壤丘陵山区高速公路路域生态脆弱性进行评价分析。应实际需要,基于遥感影像采集不同等级的样本点,确定植被、土壤、湿度、温度指数、高程、坡度作为路域生态脆弱性的评价指标,采用多元线性回归分析法构建路域生态脆弱性评价模型(总精度为83.33%,Kappa系数为0.79)。结果表明,研究路域的微度、轻度脆弱区占总面积的84.90%,说明该路域生态脆弱性程度较低,公路建设对当地生态环境影响较小;而中度、重度、极度脆弱区占总面积的15%,需加强对这些区域的环境保护,及时进行建设后生态再恢复工作。 相似文献
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This paper models a low-power high-frequency digitally controlled synchronous rectifier （SR） OUCK converter. The converter is a hybrid system with three operation modes. Digital PID controler is used. Key problems such as quantization resolution of digital pulse-width modulation （DPWM） and steady-state limit cycles of digital control switching model power supply （SMPS） are discussed, with corresponding solutions presented. Simulation of a digital control synchronous buck is performed with a fixed-point algorithm. The results show that the described approach enables high-speed dynamic performance. 相似文献
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段兴华 《雁北师范学院学报》2014,(2):67-68
文章以榆社地区社城小流域为例,以1：50 000扫描地形图为基础资料,建立DEM模型。基于DEM进行坡度、坡向、起伏度分析,得到相应的统计数据。经过水文分析得到无洼地DEM、水流长度、汇流累积量、河网等数据。由此分析研究区地貌类型特征、地貌成因、河流的发育情况等,为研究区农业生产规划、灾害预测和防治等提供相关资料。 相似文献
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The purpose of this study is to systematically showcase and evaluate how students’, schools’, and countries’ Information and Communication Technology (ICT) development levels influence students’ digital reading literacy by using the data of the Program for International Student Assessment (PISA) 2018 and the multi-level model approach. It is found that the ICT development at each level has a significant positive effect on students’ digital reading literacy, and there is a significant interactive moderating effect between different levels. The gap in ICT development levels between the countries participating in the Belt and Road Initiative (BRI) and developed economies has a “Matthew effect” in widening the digital reading literacy gap in the short term, but in the long run, the faster growth of the countries participating in BRI in ICT development levels will narrow the gap and alleviate the effect. China should make use of its advantages in ICT development to engage in global education governance, facilitate the co-development in both the ICT development level and the digital reading literacy for the countries participating in BRI, and contribute to the development of global education by opening up a new way of development. 相似文献
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从上网人数、上网人数占该地区总人数的比重及变异系数几个角度,衡量、分析我国东、东北、中、西部地区之间以及各区内省份之间存在的数字鸿沟。我国东部地区与中、西部地区之间存在明显的数字鸿沟;东部地区各省份间鸿沟很大,中部地区内较平衡;中部和东北地区代表性较好;西部地区各省份数字鸿沟也很明显。 相似文献
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To provide physically based wind modelling for wind erosion research at regional scale, a 3D computational fluid dynamics
(CFD) wind model was developed. The model was programmed in C language based on the Navier-Stokes equations, and it is freely
available as open source. Integrated with the spatial analysis and modelling tool (SAMT), the wind model has convenient input
preparation and powerful output visualization. To validate the wind model, a series of experiments was conducted in a wind
tunnel. A blocking inflow experiment was designed to test the performance of the model on simulation of basic fluid processes.
A round obstacle experiment was designed to check if the model could simulate the influences of the obstacle on wind field.
Results show that measured and simulated wind fields have high correlations, and the wind model can simulate both the basic
processes of the wind and the influences of the obstacle on the wind field. These results show the high reliability of the
wind model. A digital elevation model (DEM) of an area (3800 m long and 1700 m wide) in the Xilingele grassland in Inner Mongolia
(autonomous region, China) was applied to the model, and a 3D wind field has been successfully generated. The clear implementation
of the model and the adequate validation by wind tunnel experiments laid a solid foundation for the prediction and assessment
of wind erosion at regional scale. 相似文献
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Rudolf LUCAS 《Journal of Zhejiang University. Science. B》2010,11(2):127-135
Objective: To investigate the distributions of human leukocyte antigen (HLA)-A and-B alleles and HLA-A-B haplotypes in the Yi ethnic minority of the Yunnan Province, situated in southwestern China. Methods: DNA typing for HLA-A and-B loci was performed using the polymerase chain reaction-sequence-based typing (PCR-SBT) method on 114 randomly selected healthy individuals of the Yi population. The allelic frequencies of HLA-A and-B loci were calculated by direct counting and HLA-A-B haplotypes were estimated ... 相似文献
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Reperfusion is the key strategy in acute ST-segment elevation myocardial infarction (STEMI) care, and it is time-dependent.
Shortening the time from symptom to reperfusion and choosing the optimal reperfusion strategy for STEMI patients are great
challenges in practice. We need to improve upon the problems of low reperfusion rate, non-standardized treatment, and economic
burden in STEMI care. This article briefly reviews the current status of reperfusion strategy in STEMI care, and also introduces
what we will do to bridge the gap between the guidelines and implementation in the clinical setting through the upcoming China
STEMI early reperfusion program. 相似文献
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提出了一种将水印图像进行Arnold置乱后嵌入到经DCT域进行变化的载体图像中的数字水印算法。算法研究结果表明水印具有较好的不可见性及健壮性。同时,文中采用不同图像处理方式对嵌入水印后的图像进行了攻击实验,实验表明该算法对于JPEG压缩具有较好的鲁棒性。 相似文献
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Jun Li Ying-wei Kang Guang-yi Cao Xin-jian Zhu Heng-yong Tu Jian Li 《浙江大学学报(A卷英文版)》2008,9(7):961-969
A detailed mathematical model of a direct internal reforming solid oxide fuel cell （DIR-SOFC） incorporating with simulation of chemical and physical processes in the fuel cell is presented. The model is developed based on the reforming and electrochemical reaction mechanisms, mass and energy conservation, and heat transfer. A computational fluid dynamics （CFD） method is used for solving the complicated multiple partial differential equations （PDEs） to obtain the numerical approximations. The resulting distributions of chemical species concentrations, temperature and current density in a cross-flow DIR-SOFC are given and analyzed in detail. Further, the influence between distributions of chemical species concentrations, temperature and current density during the simulation is illustrated and discussed. The heat and mass transfer, and the kinetics of reforming and electrochemical reactions have significant effects on the parameter distributions within the cell. The results show the particular characteristics of the DIR-SOFC among fuel cells, and can aid in stack design and control. 相似文献
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以ASTER GDEM 30m DEM为基础数据提取贵州省六盘水市地表坡度、坡向、地形起伏度、地表切割深度等地形特征要素,并结合特征统计分析对该地区地貌特征进行定量分析。结果表明六盘水地区坡度在0°～88°范围内都有分布,但相对集中在5°～25;°南北坡坡向面积相差不多,分布相对均衡;中部地区地形起伏度较大,最大处达到922m,地形切割深度最大值为627m。上述结论为研究区的农业规划、水土流失、土壤侵蚀、地质灾害、生态保护等研究提供了新的空间信息平台。 相似文献
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王丹阳 《唐山师范学院学报》2014,(2):132-134
通过文献资料法、专家访谈法、逻辑分析法在阐述我国数字图书馆版权授权模式面临的困境,现有的主要的版权授权模式,分析国外数字图书馆版权授权,在此基础上,提出了我国数字图书馆版权授权模式的启示,旨在解决我国数字图书馆的版权授权问题,推动我国数字图书馆的建设和发展。 相似文献