共查询到20条相似文献，搜索用时 265 毫秒
1.
案例模型是基于案例推理方法(CBR)的推理基础,而时空数据模型是地理信息系统时空表达的概念基础。基于案例的推理方法应用于地理领域,案例表达则不能仅采取传统的表示方法,需要结合地理问题的特点;但时态地理信息系统(T-GIS)的时空数据模型又不能直接采用,需要考虑地理案例表达和推理的需求。通过对地理案例应用的分析和时空过程特点的总结,提出分级描述框架的地理案例时空过程概念表达模型,并构建其物理表达模型。本文以中国南海海洋涡旋为例进行了验证,表明此模型可应用于具有完整生命周期且变化是连续渐进地理现象的研究。 相似文献
2.
以中国西南地区2015~2017年探空数据为实验数据,使用多层感知器（MLP）神经网络回归方法建立西南地区的加权平均温度(Tm)模型。将气象参数（地表温度、水汽压）和非气象参数（高程、纬度和年积日）作为模型输入因子,由数值积分法计算得到的Tm作为学习目标,通过神经网络模型进行迭代训练从而得到中国西南地区的Tm。以2018年探空站Tm数据为参考值,对MLP模型精度进行验证,并与Bevis模型和GPT3模型进行对比分析。结果表明,MLP模型的年均RMSE和年均bias分别为1.99 K和0.15 K,比Bevis模型、GPT3模型年均RMSE分别降低1.36 K(40.6%)和1.51 K(43.1%),年均bias分别下降0.70 K（82.4%）和1.04 K（87.4%）,且该模型在中国西南区域不同高程、纬度和季节的精度与稳定性优于Bevis模型和GPT3模型。 相似文献
3.
Geography and Rural Household Income： A Village Level Study in Henan Province, China 总被引：2，自引：0，他引：2
This study uses the data from a sample survey conducted in April 2007 on 1 251 rural households in 11 villages of Henan Province, the largest less developed agricultural province in China, to examine how geography affects rural household income (RHI). The quantitative analysis indicates following results. 1) The significance of the traditional geographical factors reduces as RHI rank increases. 2) The landform does not affect the RHI significantly. The per capita income of rural household in a plain area is lower than that in a mountainous area. And 3) the capital endowment and status of non-farm economic activities contribute to the increase of RHI. But the probability and intensity of non-farm economic activities of rural households in urban outskirts villages are higher than that in non-urban outskirts villages. Based on the results, the paper further concludes that geography still plays a significant role in rural development, but it is changing over time. The agricultural resources (such as per capita arable land) significantly affect RHI with the relatively lower income level, while the geographical location shows a more significant impact on RHI with the relatively high income level. Along with economic development, the proximity replaces the traditional geographical factors such as landform and physical resources as the major determining factor in RHI. 相似文献
4.
使用亚洲区域18个IGS测站和中国区域内16个探空站2016~2018年的数据,研究GPT3模型反演天顶对流层延迟（ZTD）和大气可降水量（PWV）的精度,并与其他GPT系列模型进行对比。结果表明,GPT3-1模型估计的ZTD的bias均值和最大值均最小,分别为1.34 mm和14.06 mm;GPT3模型整体精度略优于GPT2w模型,优于GPT2模型。探空站处GPT3模型反演的PWV的bias和RMSE均表现出较强的季节性特征;由GPT3模型反演的PWV的月均值可知,GPT3-1模型比GPT3-5模型具有更高的精度和稳定性。 相似文献
5.
Normal Reference Value of Red Blood Cell Count of Chinese Presenile Men and Geographical Factors 总被引：1，自引：0，他引：1
HE Jinwei GE Miao SU Huimin LIANG Wei CHEN Hongfei 《中国地理科学(英文版)》2007,17(1):92-98
This paper aims at providing a scientific basis for unifying the normal reference value standards of red blood cell count of Chinese presenile men. The paper, using microscopical counting method, studies the relationship between the normal reference values of 38,061 samples of red blood cell count of presenile men and eight geographical factors in 297 units in China. It is found that the correlation of geographical factors and the normal reference value of red blood cell count of presenile men is quite significant (F=303.00, P=0.000). By using the method of stepwise regression analysis, one regression equation is inferred. It is concluded that if geographical data are obtained in a certain area, the normal reference value of red blood cell count of presenile men in this area can be reckoned by using the regression analysis. Furthermore, according to the geographical factors, China can be divided into eight regions: Northeast China Region, North China Region, Shanxi-Shaanxi-Inner Mongolia Region, Middle and Lower Reaches of the Changjiang River Region, Southeast China Region, Northwest China Region, Southwest China Region and Qinghai-Tibet Plateau Region. 相似文献
6.
Regional ecological health,the core of comprehensive ecosystem assessments,is an important foundation for regional exploration,environmental conservation,and sustainable development.The mountainous areas in southwest China are backward in economy,but industrialization and urbanization have been rapid in recent years.This study assessed the ecosystem health of the Sichuan and Yunnan provinces in China using a pressure-state-response(PSR)model.Spatiotemporal patterns of regional ecosystem health were analyzed from 2000 to 2016,including overall characteristics as well as local characteristics.Ecosystem health in most regions was improved over time(Y=0.0058 X–11.0132,R2=0.95,P<0.001),and areas with poorer ecosystem health decreased from half to one-third of the total area.Analysis of the primacy ratio and the variation coefficient confirmed that the gap in health scores between regions has gradually expanded since 2007,but there are more high quality regions overall(Z of Moran’s index<1.96,P>0.05).Overall,the regional ecosystems to the east of the Hu line-an imaginary line dividing east and west China into roughly equivalent parts-were healthier than those to the west.The pressure and state scores of ecosystems were determined by physiographic condition,and the response scores by government policies and social concern.The spatiotemporal patterns of ecosystem health were dominated to a greater extent by natural than anthropogenic factors,which explains why the shift in the patterns aligned with the direction of the Hu line.Dividing regions into key management areas based on natural geographical conditions and socioeconomic development could contribute to the formulation of a reasonable ecological and environmental protection policy,guaranteeing ecosystem services in the long run. 相似文献
7.
《中国地理科学(英文版)》2019,(2)
Soil organic matter(SOM) is an important parameter related to soil nutrient and miscellaneous ecosystem services. This paper attempts to improve the performance of traditional partial least square regression(PLSR) model by considering the spatial autocorrelation and soil forming factors. Surface soil samples(n = 180) were collected from Honghu City located in the middle of Jianghan Plain, China. The visible and near infrared(VNIR) spectra and six environmental factors(elevation, land use types, roughness, relief amplitude, enhanced vegetation index, and land surface water index) were used as the auxiliary variables to construct the multiple linear regression(MLR), PLSR and geographically weighted regression(GWR) models. Results showed that: 1) the VNIR spectra can increase about 39.62% prediction accuracy than the environmental factors in predicting SOM; 2) the comprehensive variables of VNIR spectra and the environmental factors can improve about 5.78% and 44.90% relative to soil spectral models and soil environmental models, respectively; 3) the spatial model(GWR) can improve about 3.28% accuracy than MLR and PLSR. Our results suggest that the combination of spectral reflectance and the environmental variables can be used as the suitable auxiliary variables in predicting SOM, and GWR is a promising model for predicting soil properties. 相似文献
8.
饮食地理文化作为地域文化中最具地方特色的重要元素,在现代人口大规模流动背景下呈现出全新的多样化局面,而基于传统认知的“南甜北咸”的地域分异已然不能代表中国现代食甜分布的空间特征。因此,本文采用网络爬虫技术,获取我国大陆31个省会城市共计约2000万条美食消费数据,从传统类菜品、主食类菜品、饮料类和甜品类菜品4个方面计算城市食甜度,在ArcGIS、MySQL软件支持下,借助GIS空间分析和数理统计方法探究我国现代食甜习惯的空间分布特征,分析影响食甜分布的因素。研究发现：① 中国食甜在空间分布上存在显著的地域分异特征,聚类分析评价参数R 2高达0.88,现代食甜习惯总体呈现“东高北中,西微内低”的包围式格局;② 从整体抑或局部角度,在1%显著性水平上莫兰指数均为正,中国食甜分布呈现显著的空间正相关关系,形成特色鲜明的3个地理集聚区,即以苏浙沪闽为主的东南沿海高甜集聚区,以渝黔川为主的西南内陆低甜集聚区和以陕宁为主的西北内陆低甜集聚区;③ 构建了中国现代食甜习惯分布影响因素模型,其拟合精度为0.82,分析结果显示降水、湿度、气温等气象要素及地理位置是影响现代我国食甜空间分布的重要因素。 相似文献
9.
《中国地理科学(英文版)》2019,(5)
Timely monitoring and early warning of soil salinity are crucial for saline soil management. Environmental variables are commonly used to build soil salinity prediction model. However, few researches have been done to summarize the environmental sensitive variables for soil electrical conductivity(EC) estimation systematically. Additionally, the performance of Multiple Linear Regression(MLR), Geographically Weighted Regression(GWR), and Random Forest regression(RFR) model, the representative of current main methods for soil EC prediction, has not been explored. Taking the north of Yinchuan plain irrigation oasis as the study area, the feasibility and potential of 64 environmental variables, extracted from the Landsat 8 remote sensed images in dry season and wet season, the digital elevation model, and other data, were assessed through the correlation analysis and the performance of MLR, GWR, and RFR model on soil salinity estimation was compared. The results showed that: 1) 10 of 15 imagery texture and spectral band reflectivity environmental variables extracted from Landsat 8 image in dry season were significantly correlated with soil EC, while only 3 of these indices extracted from Landsat 8 image in wet season have significant correlation with soil EC. Channel network base level, one of the terrain attributes, had the largest absolute correlation coefficient of 0.47 and all spatial location factors had significant correlation with soil EC. 2) Prediction accuracy of RFR model was slightly higher than that of the GWR model, while MLR model produced the largest error. 3) In general, the soil salinization level in the study area gradually increased from south to north. In conclusion, the remote sensed imagery scanned in dry season was more suitable for soil EC estimation, and topographic factors and spatial location also play a key role. This study can contribute to the research on model construction and variables selection for soil salinity estimation in arid and semiarid regions. 相似文献
10.
地理命名实体分类体系的设计与应用分析 总被引：2，自引：0，他引：2
自然语言是一种重要的空间数据来源,从自然语言中获取地理空间信息是地理信息科学的重要研究议题。完善的地理命名实体分类体系,有助于实现自然语言中地理空间信息的解析、存贮、组织、管理、分析及共享应用。现有的基础地理要素分类体系、地名分类体系和组织机构分类体系,分别侧重于不同的应用领域,只能表达自然语言中的部分地理命名实体,没有考虑时空关联特性。本文在参照大量相关标准的基础上,根据大量自然语言文本的标注结果,以地理命名实体所指代的空间位置、地理特征和属性作为分类标准,采用主分表和复分表相结合的方式,设计了地理命名实体分类体系(简称"GNEC")。采用定量和定性相结合的方法,分析了GNEC与GB/T18521-2001,GB/T13923-2006,CHG IS的地名分类体系、ADL的FTT词表之间的兼容性,并以中文文本的地理命名实体解析和地图服务为例,验证了GNEC的应用性能。多样性是自然语言中地理实体描述的重要特征,而分类体系主要实现地理命名实体的概念化操作。因此,在GNEC基础上构建本体,将成为解决这一问题的有效途径。 相似文献
11.
江西省典型县域经济差异影响因子地理探测研究 总被引：2，自引：0，他引：2
地理环境因子对区域经济差异的影响一直是国内外学者关注的重点及热点问题,探究各因子对区域经济差异的影响力,科学揭示各因子的作用机制,将为区域经济发展战略的制定提供重要指导依据。本文利用多元回归和地理探测器等方法,综合探测了地形、地貌、土地利用、交通区位等因子对江西典型贫困县及富裕县县域经济差异的影响,深入对比分析了各因子的影响力、交互作用及指示作用,总结主导影响因子及其在2类县域的演变趋势,提出分类精准施策的建议,进一步深化了对该问题的研究。结果表明：① 所选的9个地理环境因子均对贫困县及富裕县县域经济产生影响,不同类型县域的主导影响因子及不同因子对同一类型县域的影响力均存在差异;② 从主导影响因子来看,贫困县主要受自然条件、地理区位的影响,而富裕县主要受资源丰度、交通区位的影响;③ 对比2种县域经济差异的显著影响因子,发现由贫困地区到富裕地区主导影响因素逐步由自然禀赋等不可控因素向交通、技术等可控因素变化;④ 经济发展过程中,应根据区域经济主导影响因子因地制宜,分类精准施策。同时,利用影响因子的强交互作用性,注重对该类因子的改善,对促进经济发展可起到事半功倍的效果。 相似文献
12.
高精度曲面建模方法（High Accuracy Surface Modeling, HASM）,从理论上解决了传统方法在插值过程中峰值削平和边界震荡等问题。其模拟精度相对于经典插值方法有很大提高,已成功应用于人口密度、土壤属性,以及气候要素等领域的空间制图。然而,由于地面气象站点数量和分布的限制,使得HASM仅依靠站点数据难以得到高精度的空间降水估计数据,因此,本文以地貌与气候类型复杂多样的我国中西部地区2010年年降水量空间分布模拟为例,采用混合插值法进行HASM区域降水模拟。结果表明,TRMM作为背景场的HASM模拟的年降水量精度,在全局和局部明显优于IDW、Spline和Kriging等经典插值方法的结果,作为背景场的HASM模拟精度,MAE和RMSE分别为125.15 mm和155.80 mm,其他方法最好的模拟结果比其误差值分别高出53.6%和54.5%;其模拟误差在不同子区域都较小;各种方法在平原的精度都高于山区的精度。 相似文献
13.
分析中国科学院（CAS）、法国国家空间研究中心（CNES）、加拿大自然资源部大地测量局（NRCan）和加泰罗尼亚理工大学（UPC）2021-01～08的全球实时电离层格网(RT-GIM)产品的精度。结果表明：1）以IGS事后全球电离层格网（GIM）为参考,CAS、CNES、NRCan和UPC产品的RMS分别为3.93 TECu、4.01 TECu、4.50 TECu和3.86 TECu;2）以基准站dSTEC为参考,CAS、CNES、NRCan和UPC产品的STD分别为4.42 TECu、4.40 TECu、4.96 TECu和4.42 TECu。在全球范围内选取21个测站进行连续7 d的定位测试,以高程方向残差95%分位数统计不同实时电离层产品的定位增益。相比于广播电离层模型的定位结果,CAS、CNES、NRCan和UPC产品在北半球高程方向的定位精度分别提升11.9%、18.3%、3.4%和15.5%。 相似文献
14.
???????????48??IGS?2009-2011??????????????????ZTD?????????????EGNOS???????ZTD???????????????????????1??????????????????IGS?????ZTD??EGNOS???????ZTD???????????????-0.18 cm??5.98 cm?????й?????????0.81 cm??6.13 cm??2????????????????????????仯????????????????＾??С??????????????????????С??3????????????????γ?????仯???????????????????????????γ????????????????????????????????γ????????????????????仯????С??4:???????????γ?????????????????????????????????仯????? 相似文献
15.
I.INTROIjUCTIONSincethereformandopening-up,FOreignDirectinvestments(FDIs)havebeenemployedinChineseeconomicdevelopment.SomeresearchresultsshowthatFDIsinChineseeconomicdevelOPmenthavechangedaseriesofeconomicstructure,suchas,investmentstructure,propertystructtire,tradestructure,technologystructureetc.whichsuggeststhatrolesofaflsinChineseeconomicdevelopmentshouldbeseriouslytakenintoconsiderationinstudyingtheregionaldevelopmentissues.Evidently,theregionaldifferenceofrolesofFDIsisdetendn… 相似文献
16.
中国县域农村贫困的空间模拟分析 总被引：2，自引：0，他引：2
以中国县级行政区划为研究单元,从自然和社会经济因素中选取贫困的影响因子,建立评价指标体系,利用GIS空间分析和 BP人工神经网络,模拟各县域的自然致贫指数和社会经济消贫指数,并在分析贫困内在形成原因的基础上,明晰了空间贫困的分布特征。结果显示：自然因素是现阶段中国县域主要的致贫原因,全国县域自然致贫指数的分布呈现出明显随纬度和经度地带性分布的规律,自北而南、自西而东逐次呈带状排列分布。社会经济因素对贫困起到一定的缓解作用,全国县域社会经济消贫指数的空间分布较为破碎,各省区内部县域社会经济消贫指数的变异系数均大大高于自然致贫指数的变异系数。全国贫困压力指数以“黑河-百色”一线为界,东中西差异显著,呈现“大分散、小聚集”的空间分布格局。本文识别的贫困县与国家确定的重点扶贫县在空间上具有较高的重合性。 相似文献
17.
Landslide susceptibility maps(LSMs) play a vital role in assisting land use planning and risk mitigation. This study aims to optimize causative factors using logistic regression(LR) and an artificial neural network(ANN) to produce a LSM. The LSM is produced with 11 causative factors and then optimized using forward-stepwise LR(FSLR), ANN, and their combination(FSLR-ANN) until eight causative factors were found for each method. The ANN method produced superior validation results compared with LR. The ROC values for the training data set ranges between 0.8 and 0.9. On the other hand, validation with the percentage of landslide fall into LSM class high and very high, ANN method was higher(92.59%) than LR(82.12%). FSLR-ANN with nine causative factors gave the best validation results with respect to area under curve(AUC) values, and validation with the percentage of landslide fall into LSM class high and very high. In conclusion, ANN was found to be better than LR when producing LSMs. The best Optimization was combination of FSLR-ANN with nine causative factors and AUC success rate 0.847, predictive rate 0.844 and validation with landslide fall into high and very high class with 91.30%. It is an encouraging preliminary model towards a systematic introduction of FSLR-ANN model for optimization causative factors in landslide susceptibility assessment in the mountainous area of Ujung Loe Watershed. 相似文献
18.
??ITRF2008??????й???????5??IGS??????WUHN??BJFS??URUM??KUNM??SHAO??2012??????????????TriP?????????????????????????С??????????????????????????????????????????н?????????????????????????????????GAMIT/GLOBK????????????????????з?????????ж???????????????й??????IGS???????????д??????????????????????????????????????????????????URUM??KUNM??BJFS??SHAO?????????????????????BPPL+WN????WUHN??????N??E??U????????????????з?????????????BPPL+WN??FN+WN??PL+WN??????????BPPL+WN??????????а???????????????????????????2 mm??BPPL???????WN??????1/10???????0.28??0.89 mm????????????????С???????????????????????????????????С??????TriP?????????????????????????????????????????????????? 相似文献
19.
��BP�����缼��̽���봨����ǰ�����NmF2�쳣�Ŷ� 总被引：2，自引：0，他引：2
????UCAR??????????F2???????????????NmF2??????????????缼???????????????NmF2???????????DOY???????LT??????LON??γ??LAT??F10.7????????FLUX???????????NmF2???????????????????NmF2????????ο????????????????????????????2008??5??12????7.9??????????и??????NmF2???????6??4??6??8?????С?30%???????3??2??9??10????????????40%?? 相似文献
20.
Foreign direct investments (or FDIs) have been employed since the early 1980s and they have become more and more important
in Chinese economic development. However, the roles of FDIs are very different between regions, partly due to the different
locational preference of various source countries. Some facts show that FDIs from Hongkong - Macao indicate a strong locational
preference. Therefore, this paper attempts to make an empirical research on the locational preference of Hongkong - Macao’s
FDIs and their spatial diffusion under the support of statistical data with regression analysis. In this paper, three statistical
models, including the special location model, the general location model and the spatial diffusion model, are created. The
results show that this kind of analysis is successful. The major conclusions are as follows. (1) The optimum location for
FDIs from Hongkong - Macao lies in the coastal area, especially Guangdong, Hainan, Jiangsu, Shandong, Fujian provinces. Besides,
Hubei Province is also an important region. (2) The FDIs from Hongkong - Macao in China have diffused gradually from the coastal
provinces to the inland regions, the northern and the metropolis and from the locations that had attracted a large number
of investments to their vicinities since the 1990s. (3) The special location factors, such as the border effect, the unique
social and kinship ties are the key factors determining the special locational distribution. (4) The general location and
spatial diffusion of Hongkong - Macao’s FDIs are the results of interplay of several economic factors. They are the economic
scale and advantage, the growth rate, the labor force and economic extrovert etc. 相似文献