检索结果-南通市图书馆

A novel unsupervised deep learning method for the generalization of urban form

Geo-Spatial Information Science 2022年第4期25卷 568-587页

作者： Jihong Cai Yimin Chen School of Geography and Planning Sun Yat-sen UniversityGuangzhouChina

Accurate delineation of urban form is essential to understand the impacts that urbanization has on the environment and regional climate.Conventional supervised classification of urban form requires a rigidly defined scheme and high-quality sample data with class labels.Due to the complexity of urban systems,it is challenging to consistently define urban form types and collect metadata to describe them.Therefore,in this study,we propose a novel unsupervised deep learning method for urban form delineation while avoiding the limitations of conventional super-vised urban form classification methods.The novelty of the proposed method is the Multiscale Residual Convolutional Autoencoder(MRCAE),which can learn the latent representation of differ-ent urban form types.These vectors can be further used to generalize urban form types by using Self-Organizing Map(SOM)and the Gaussian Mixture Model(GMM).The proposed method is applied in the metropolitan area of Guangzhou-Foshan,China.The MRCAE model along with SOM and GMM is used to generalize the urban form types from satellite images.The physical and functional properties of each urban form type are also analyzed using several auxiliary datasets,including building footprints,Points-of-Interests(POIs)and Tencent User Density(TUD)data.The results reveal that the urban form map generated based on the MRCAE can explain 55%of the building height distribution and 55%of the building area distribution,which are 2.1%and 3.3%higher than those derived from the conventional convolutional autoencoder.As the information of urban form is essential to urban climate models,the results presented in this study can become a basis to refine the quantification of urban climate parameters,thereby introducing the urban heterogeneity to help understand the climate response of future urbanization.

关键词： Convolutional autoencoder Self-Organizing Map(SOM) Gaussian Mixture Model(GMM) urban form clustering

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Projected Regional 1.50℃and 2.00℃Warming Threshold-crossing Time Worldwide Using the CMIP6 Models

引用

Chinese Geographical Science 2023年第6期33卷 1095-1108页

作者： MENG Yali DUAN Keqin SHANG Wei SHI Peihong LI Shuangshuang CHENG Ying CHEN Rong ZHANG Zhaopeng School of Geography and Tourism Shaanxi Normal UniversityXi’an710119China

The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by spatial and temporal sensitivities.To better understand the regional warming response to global warming at 1.50℃and 2.00℃,we detected the 1.50℃and 2.00℃warming threshold-crossing time(WTT)above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6(CMIP6)models.Our findings indicate that the 1.50℃or 2.00℃WTT differs substantially worldwide.The warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–2100.Consequently,the land would experience a 1.50℃(2.00℃)warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50℃(2.00℃)WTT.Meanwhile,the Southern Ocean between 0°and 60°S considerably slows down the global 1.50℃and 2.00℃WTT.In 2040–2060,over 98.70%(77.50%),99.70%(89.30%),99.80%(93.40%),and 100.00%(98.00%)of the land will have warmed by over 1.50℃(2.00℃)under SSP(Shared Socioeconomic Pathway)1–2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5,respectively.We conclude that regional 1.50℃(2.00℃)WTT should be fully considered,especially in vulnerable high-latitude and high-altitude regions.

关键词： CMIP6(Coupled Model Intercomparison Project phase 6) global warming 1.50℃warming time 2.00℃warming time regional differences

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Response of nephelometric turbidity to hydrodynamic particle size of fine suspended sediment

引用

International Journal of Sediment Research 2020年第5期35卷 444-454页

作者： Christina Bright Sarah Mager Sophie Horton School of Geography University of Otago

Turbidity is used as a surrogate for suspended sediment concentration(SSC),and as a regulatory tool for indicating land use disturbance and environmental protection.Turbidity relates linearly to suspended material,however,can show non-linear responses to particulate organic matter(POM),concomitant with changes in particle size distribution(PSD).In the paper the influence of ultra-fine particulate matter(UFPM) on specific turbidity and its association with POM in suspended sediment are shown for alpine rivers in the Southern Alps of New Zealand.The approach was two-fold:a field-based investigation of the relations between SSC,POM,and turbidity sampled during event flow;and experimental work on hydrodynamic particle size effects on SSC POM,PSD,and turbidity.Specific turbidity changes over event flow and are sensitive to increasing proportional amounts of sand,UFPM,and POM in suspension.Furthermore,the UFPM is the size fraction(<6 μm) where POM increases.The implications of the current study are that the slopes of turbidity-SSC relations are undesirable in locations that may be dominated by cyclic release of POM or distinct pulses of fine-grained material.At locations where the turbidity-SSC slopes approximate 2,the POM proportion is usually <10% of the total suspended load.However,when turbidity-SSC slopes are <1 this is likely caused by high amounts of side-scatter from UFPM concomitant with higher proportions of POM.Thus,the use of turbidity as a proxy for determining SSC may have serious consequences for the measurement of representative suspended sediment data,particularly in locations where POM may be a significant contributor to overall suspended load.

关键词： Turbidity Nephelometry Suspended sediment concentration Particle size distribution Particulate organic matter

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Evaluation of hydro-chemistry in a phreatic aquifer in the Vindhyan Region, India, using entropy weighted approach and geochemical modelling

引用

Acta Geochimica 2023年第4期42卷 648-672页

作者： Ashutosh Mishra Aman Rai Prabuddh Kumar Mishra Suresh Chand Rai Department of geography Delhi School of EconomicsUniversity of DelhiDelhi 110027India Department of geography Shivaji CollegeUniversity of DelhiDelhi 110027India

Groundwater quality monitoring and geochemical characterization in the phreatic aquifer are critical for ensuring universal and equitable access to clean,reliable,and inexpensive drinking water for all.This research was intended to investigate the hydrogeochemical attributes and mechanisms regulating the chemistry of groundwater as well as to assess spatial variation in groundwater quality in Satna district,India.To accomplish this,the groundwater data comprising 13 physio-chemical parameters from thirty-eight phreatic aquifer locations were analysed for May 2020 by combining entropy-weighted water quality index(EWQI),multivariate statistics,geochemical modelling,and geographical information system.The findings revealed that the groundwater is fresh and slightly alkaline.Hardness was a significant concern as 57.89% of samples were beyond the permissible limit of the World Health Organisation.The dominance of ions were in the order of Ca^(2+)> Na^(+)> Mg^(2+)> K^(+) and HCO_(3)^(-)> SO_(4)^(2-)> Cl^-> NO_(3)^(-)> F^(-).Higher concentration of these ions is mainly concentrated in the northeast and eastern regions.Pearson correlation analysis and principal component analysis(PCA) demonstrated that both natural and human factors regulate groundwater chemistry in the region.The analysis of Q-mode agglomerative hierarchical clustering highlighted three significant water clusters.Ca-HCO_3 was the most prevalent hydro-chemical facies in all three clusters.Geochemical modelling through various conventional plots indicated that groundwater chemistry in the research region is influenced by the dissolution of calcite/dolomite,reverse ion exchange,and by silicate and halite weathering.EWQI data of the study area disclosed that 73.69% of the samples were appropriate for drinking.Due to high salinity,Magnesium(Mg^(2+)),Nitrate(NO_(3)^(-)),and Bicarbonate(HCO_(3)^(-)) concentrations,the north-central and north-eastern regions are particularly susceptible.The findings of the study may be accomplished by policymakers and groundwat

关键词： Groundwater quality assessment EWQI Multivariate statistical analysis Geochemical modelling Hydrogeochemical processes Saturation index

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

引汉济渭工程水源区与受水区并发干旱概率增加

引用

Journal of Geographical Sciences 2022年第10期32卷 1998-2012页

作者：王小红刘宪锋孙高鹏 School of Geography and Tourist Shaanxi Normal UniversityXi’an 710119China

Water diversion projects are an effective measure to mitigate water shortages in water-limited areas.Understanding the risk of such projects increasing concurrent drought between the water intake and receiving regions is essential for sustainable water management.This study calculates concurrent drought probability between the water intake and receiving regions of the Hanjiang to Weihe River Water Diversion Project using Standardized Precipitation Index and Copula functions.Results showed an increasing trend in drought probability across both the water intake and receiving regions from 2.67%and 8.38%to 12.47%and 14.18%,respectively,during 1969-2018.The return period of concurrent drought decreased from 111.11 to 13.05 years,indicating larger risk of simultaneous drought between the two regions.Projections from CMIP6 suggested that under the SSP 2-4.5 and 5-8.5 scenarios,concurrent drought probability would increase by 2.40%and 7.72%in 2019-2050 compared to that in 1969-1990,respectively.Although increases in precipitation during 2019-2050 could potentially alleviate drought conditions relative to those during 1991-2018,high precipitation variability adds to the uncertainty about future concurrent drought.These findings provide a basis for better understanding concurrent drought and its impact on water diversion projects in a changing climate,and facilitate the establishment of adaptation countermeasures to ensure sustainable water availability.

关键词： concurrent drought climate change Copula SPI Hanjiang to Weihe River Water Diversion Project

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Quantitative assessment of the spatial distribution of^(239+240)Pu inventory derived from global fallout in soils from Asia and Europe

引用

Journal of Geographical Sciences 2022年第4期32卷 605-616页

作者： CAO Liguo ZHOU Zhengchao WANG Ning XIAO Shun School of Geography and Tourism Shaanxi Normal UniversityXi'an 710119China

Due to the atmospheric nuclear weapon tests carried out,terrestrial environments have been extensively contaminated by global fallout of plutonium(Pu)worldwide.The^(239+240)Pu inventories in soil profiles from undisturbed and flat forest or grasslands(reference sites)mainly from Europe and Asia are considered as important background for evaluating soil erosion.Thus,we conducted a literature survey over an area extending from 2.6°W to 148.9°E and from 53.2°S to 76.6°N,with the purpose of analyzing the spatial distribution of^(239+240)Pu inventories and possible controlling factors.The aim of this work was to derive an empirical model of^(239+240)Pu inventory based on currently available^(239+240)Pu data,precipitation and latitude.The results show that,in general,the latitudinal distribution of^(239+240)Pu inventory was consistent with the UNSCEAR reports.However,the^(239+240)Pu inventories are higher than the UNSCEAR data,especially in the Northern Hemisphere.In addition,close relationships(at the 0.01 significance level)were identified between^(239+240)Pu inventories and annual precipitation and latitude.An empirical formula was therefore developed to estimate^(239+240)Pu inventories in soils based on latitude and precipitation data.However,future research may require more data of measured^(239+240)Pu inventories in soil profiles that can be used to compare,validate and improve upon the accuracy of the inferred empirical equation.

关键词： spatial distribution plutonium global fallout precipitation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Toward inclusive list-making for trade liberalization in environmental goods to reduce carbon emissions

引用

geography and Sustainability 2023年第3期4卷 200-212页

作者： Xiyan Mao Hanyue Liu Jingxuan Gui Peiyu Wang School of Geography and Ocean Science Nanjing UniversityNanjing 210023China

The Asia-Pacific Economic Cooperation(APEC)is contemplating expanding its list of environmental goods(EG)for trade liberalization to fight climate change.In support of doing so,this study proposes that a long list that retains controversies is better for carbon emission reduction than a short common list.This study examines four mechanisms of longer lists:enlarging market scales,enriching product mixes,enhancing product sophistication,and enriching trade patterns.Using China’s emerging EG trade during the 2001-2015 period as a case study,this study compares four EG lists with different EG.The results show that:(1)a longer list reduces carbon emissions from both imports and exports,making domestic regions with different advantages have better chances of improving carbon efficiencies.(2)Product sophistication reduces the emission gap between trading partners,regardless of the length of EG lists.(3)China’s EG exports contribute to carbon reduction in leading regions,while EG imports provide laggard regions with better chances of reducing carbon emissions.These findings provide three implications for future list-making:it is important to(1)seek a long and inclusive list rather than a short common list,(2)shift the focus from environmental end-use to the technological contents of products,and(3)balance the demand of laggard regions to import and the capacity of leading regions to export.

关键词： Carbon emissions Global environmental governance Environmental goods Inequality Product sophistication

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Urban Agglomerations in China: Characteristics and Influencing Factors of Population Agglomeration

引用

Chinese Geographical Science 2023年第4期33卷 719-735页

作者： CAO Yongwang ZHANG Rongrong ZHANG Dahao ZHOU Chunshan School of Geography and Planning Sun Yat-sen UniversityGuangzhou 510006China

Urban agglomeration(UA)is an advanced spatial economic form formed and developed in the process of rapid industrialization and urbanization,and an important carrier of urbanization and economic development.The economy has developed rapidly in the recent decades of China,and the UAs have also developed rapidly.However,as a large population country,the population distribution and changes of UAs in China has unique characteristics.Using the fifth,sixth and seventh population census data,spatial auto-correlation and spatial econometric models,we analyzed the spatial-temporal evolution characteristics and influencing factors of population agglomeration in China’s UAs.Results revealed that:1)from 2000 to 2020,the population gradually converged into UAs,and the characteristics of population agglomeration in different development degree of UAs differ.The higher the development degree of UA,the higher the population agglomeration degree.Besides,UAs are the main area with the most significant population agglomeration degree,and the spatial autocorrelation show that the cities with similar degree tend to be concentrated in space.The urban population gathering in UAs has a certain positive spillover effect on population size of neighboring cities.2)Economic development and social conditions factors are important factors affecting population agglomeration degree in UAs.The main factors of population gather into UAs are similar with the outside UAs,but the positive promotion of urbanization rate and proportion of tertiary industry in GDP on population agglomeration of UAs in China are enhancing from 2000 to 2020.Meanwhile,the other factors,such as high-quality public services,good urban living environment conditions,high-quality medical and educational resources,are also important factors to promote urban population gather into UAs.This study provides a basis for formulating the development planning of UAs in China,and enriches the relevant theoretical research of population evolution and influencing factors of UAs.

关键词： urban agglomerations(UAs) population agglomeration influencing factors spatial econometric models China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Exploring point zero:a study of 20 Chinese cities

引用

Geo-Spatial Information Science 2020年第3期23卷 258-272,I0006页

作者： Qi Zhou Mingjian Zhai Wenhao Yu School of Geography and Information Engineering China University of GeosciencesWuhanChina

A point zero represents a central geographical location of a city,which is essential for not only measuring distances,but also understanding the historical and/or cultural origin of a city.Although extensive studies have focused on delineating city centers,to our knowledge,no studies have paid attention to determining the location for a point zero.Here,our goal is to investigate various potential approaches for identifying such a location.Specifically,three typical approaches,geometric-based,topological-based,and thematic-based,are proposed to recommend point zeros and different scales,administrative divisions,kernel density sur-faces,and regions enclosed by ring roads are used for analysis.The effectiveness of different approaches and scales are evaluated and compared by calculating an offset distance between recommended and actual point zero locations in 20 Chinese cities.Using the different approaches,the average offset distance for most Chinese cities is 2-4 km,and the thematicbased approach performs best.Both the topological-based and thematic-based approaches are less sensitive to the analyzed scale than the geometric-based approach.The results indicate that it is possible to determine the approximate location for a point zero from geographical data.Based on the buffer zone of such a location,an actual point zero may further be recommended.

关键词： Point zero city center geographical data Chinese cities

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Contribution of underlying terrain to sand dunes: evidence from the Qaidam Basin, Northwest China

引用

Journal of Arid Land 2021年第12期13卷 1215-1229页

作者： LI Jiyan QU Xin DONG Zhibao CAI Yingying LIU Min REN Xiaozong CUI Xujia School of Geography Science Taiyuan Normal UniversityJinzhong 030619China School of Geography and Tourism Shaanxi Normal UniversityXi'an 710119China

Underlying terrain strongly influences dune formation.However,the impacts of underlying terrain on the dune formation are poorly studied.In the present research,we focused on dunes that formed in the alluvial fans and dry salt flats in the Qaidam Basin,Northwest China.We quantified the dunes'sediment characteristics on different types of underlying terrain and the terrain's effects on the surface quartz grains by analyzing grain-size distribution,soluble salt contents and grain surface micro-textures.Results showed that barchan dunes were dominated by medium sands with a unimodal frequency distribution,whose peak corresponded to the saltation load.Linear dunes were mainly composed of fine sands with a bimodal frequency distribution,whose main peak represented the saltation load,and whose secondary peak represented the modified saltation or suspension load.Sand was transported from source area by running water(inland rivers)over short distances and by wind over relatively longer distances.Thus,quartz grains had poor roundness and were dominated by sub-angular and angular shapes.Surface micro-textures indicated that dune sands were successively transported by exogenic agents(glaciation,fluviation and wind).Soluble salt contents were low in dunes that developed in the alluvial fans,which represented a low-energy chemical environment,so the grain surface micro-textures mainly resulted from mechanical erosion,with weak micro-textures formed by SiO2 solution and precipitation.However,soluble salt contents were much higher in dunes that developed in the dry salt flats,which indicated a high-energy chemical environment.Therefore,in addition to micro-structures caused by mechanical erosion,micro-textures formed by SiO2 solution and precipitation also well developed.Our results improve understanding of the sediment characteristics of dune sands and the effects of underlying terrain on dune development in the Qaidam Basin,China.

关键词： dune grain-size distribution soluble salts surface micro-texture Qaidam Basin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：