Due to global warming, extreme weather and climate events are becoming more frequent, highlighting the need to explore the changing characteristics of precipitation in China, including extreme precipitation. A cluster...Due to global warming, extreme weather and climate events are becoming more frequent, highlighting the need to explore the changing characteristics of precipitation in China, including extreme precipitation. A clustering algorithm was developed to classify summer(June, July, and August) daily precipitation in China from 1961 to 2020, considering spatial distribution, standard deviations, and frequency of extreme precipitation events. The results reveal six distinct precipitation climate zones, a classification that differs from previous divisions. While overall precipitation has decreased in most regions, the frequency of extreme precipitation events has increased across all clusters, indicating a shift in precipitation distribution patterns. Analysis shows that the weakened Lake Baikal blocking high and strengthened Mongolian cyclone influence the arid region in northwest China(Cluster 1), which is characterized by the lowest precipitation.The transition zone between the monsoon and arid region(Cluster 2) is affected by the Mongolian cyclone, water vapor transport from the Indian Ocean, and shifts in the monsoon boundary. Clusters 3 and 4 represent areas associated with advancement and retreat of the summer monsoon. In the Meiyu region, two distinct subregions have been identified exist.Cluster 4 is primarily influenced by the East Asia-Pacific wave train. Despite sharing similar climate drivers and proximity,Clusters 4 and 5 differ significantly due to topographic variations and disparate levels of urbanization. Cluster 5 exhibits a higher average precipitation, greater variability, and more frequent extreme events. Cluster 6 exhibits the highest overall precipitation in the coastal areas of Guangdong and Guangxi, where abundant water vapor contributes to a higher frequency of extreme precipitation. In addition, anthropogenic activities and urbanization significantly influence precipitation in Beijing-Tianjin-Hebei and Yangtze River Delta regions. This research proposes a precipitation classification scheme integrating multiple precipitation parameters, providing support for risk management and mitigation strategies in the face of increasing extreme precipitation events.展开更多
Historically, hotel classification systems were developed to ensure safe and reliable lodging and food for travellers at a time when very few such trustworthy establishments existed. With the unprecedented growth of i...Historically, hotel classification systems were developed to ensure safe and reliable lodging and food for travellers at a time when very few such trustworthy establishments existed. With the unprecedented growth of international tourism in the past fifty years, during which hospitality has reach the status of a mature industry, the focus has moved from consumer protection (generally guaranteed by national regulations and legislation) to consumer information. Today, standardization and competitive marketing of hotel services to foreign customers and tourist professionals have emerged as driving forces for instituting a local or national hotel classification system.展开更多
Lunar landforms are the results of geological and geomorphic processes on the lunar surface.It is very important to identify the types of lunar landforms.Geomorphology is the scientific study of the origin and evoluti...Lunar landforms are the results of geological and geomorphic processes on the lunar surface.It is very important to identify the types of lunar landforms.Geomorphology is the scientific study of the origin and evolution of morphological landforms on planetary surfaces.Elevation and relief amplitude are the most commonly used geomorphic indices in geomorphological classification studies.Previous studies have determined the elevation classification criteria of the lunar surface.In this paper,we focus on the classification criteria of the topographic relief amplitude of the lunar surface.To estimate the optimal window for calculating the relief amplitude of the lunar surface,we use the mean change-point method based on LOLA(Lunar Orbiter Laser Altimeter)Digital Elevation Model(DEM)data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera(SELENE TC).The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar landforms.Taking the topographic relief amplitudes of 100 m,200 m,300 m,700 m,1500 m and 2500 m as thresholds,the lunar surface is divided into seven geomorphic types,including minor microrelief plains(<100 m),minor microrelief platforms[100 m,200 m),microrelief landforms[200 m,300 m),small relief landforms[300 m,700 m),medium relief landforms[700 m,1500 m),large relief landforms[1500 m,2500 m)and extremely large relief landforms(≥2500 m).The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins,while the minor microrelief platforms are mainly in the transition regions between the maria and highlands.The microrelief landforms are mainly located in regions with relatively high topography,such as wrinkle ridges and sinuous rilles in the mare.The small relief landforms are mainly scattered in the central peak and floor fractures of craters.The medium relief landforms are mainly distributed in the transition regions between crater floors and crater walls,between crater walls and crater rims,between basin floors and basin walls,and between basin walls and basin rims.Large and extremely large relief landforms are mainly found along crater walls and basin walls.The classification criteria determination for assessing lunar surface relief amplitude described in this paper can provide important references for the construction of digital lunar surface geomorphology classification schemes.展开更多
Social network analysis(SNA) has been introduced to China's Mainland since the end of last century. It is often stated that SNA research has experienced rapid growth in China over these years, but few studies have...Social network analysis(SNA) has been introduced to China's Mainland since the end of last century. It is often stated that SNA research has experienced rapid growth in China over these years, but few studies have been conducted to prove the statement. This paper aims at exploring the research status and development of SNA in China by a critical assessment of journal articles. Our findings show that SNA is an evolving and diversified research area which has rich themes and topics, and can be applied to those studies on different levels, context and disciplines, and attract researchers and scholars from various fields and domains. In addition, the information community(Library & Information Science and Information Systems) plays a leading role in the SNA related researches. The paper also points out the research on SNA in China has some limitations, so it proposes several implications for the future development of SNA research from perspectives of information science.展开更多
Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraph...Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).展开更多
基金National Natural Science Foundation of China(U2442202, 42274217, 62441501)Key Innovation Team of China Meteorological Administration (CMA2024ZD01)Scientific Research Foundation of CUIT (376278, KYTZ202158)。
文摘Due to global warming, extreme weather and climate events are becoming more frequent, highlighting the need to explore the changing characteristics of precipitation in China, including extreme precipitation. A clustering algorithm was developed to classify summer(June, July, and August) daily precipitation in China from 1961 to 2020, considering spatial distribution, standard deviations, and frequency of extreme precipitation events. The results reveal six distinct precipitation climate zones, a classification that differs from previous divisions. While overall precipitation has decreased in most regions, the frequency of extreme precipitation events has increased across all clusters, indicating a shift in precipitation distribution patterns. Analysis shows that the weakened Lake Baikal blocking high and strengthened Mongolian cyclone influence the arid region in northwest China(Cluster 1), which is characterized by the lowest precipitation.The transition zone between the monsoon and arid region(Cluster 2) is affected by the Mongolian cyclone, water vapor transport from the Indian Ocean, and shifts in the monsoon boundary. Clusters 3 and 4 represent areas associated with advancement and retreat of the summer monsoon. In the Meiyu region, two distinct subregions have been identified exist.Cluster 4 is primarily influenced by the East Asia-Pacific wave train. Despite sharing similar climate drivers and proximity,Clusters 4 and 5 differ significantly due to topographic variations and disparate levels of urbanization. Cluster 5 exhibits a higher average precipitation, greater variability, and more frequent extreme events. Cluster 6 exhibits the highest overall precipitation in the coastal areas of Guangdong and Guangxi, where abundant water vapor contributes to a higher frequency of extreme precipitation. In addition, anthropogenic activities and urbanization significantly influence precipitation in Beijing-Tianjin-Hebei and Yangtze River Delta regions. This research proposes a precipitation classification scheme integrating multiple precipitation parameters, providing support for risk management and mitigation strategies in the face of increasing extreme precipitation events.
文摘Historically, hotel classification systems were developed to ensure safe and reliable lodging and food for travellers at a time when very few such trustworthy establishments existed. With the unprecedented growth of international tourism in the past fifty years, during which hospitality has reach the status of a mature industry, the focus has moved from consumer protection (generally guaranteed by national regulations and legislation) to consumer information. Today, standardization and competitive marketing of hotel services to foreign customers and tourist professionals have emerged as driving forces for instituting a local or national hotel classification system.
基金Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDB41000000National Natural Science Foundation of China,No.42130110,No.41571388Key Project of National Basic Work of Science and Technology,No.2015FY210500。
文摘Lunar landforms are the results of geological and geomorphic processes on the lunar surface.It is very important to identify the types of lunar landforms.Geomorphology is the scientific study of the origin and evolution of morphological landforms on planetary surfaces.Elevation and relief amplitude are the most commonly used geomorphic indices in geomorphological classification studies.Previous studies have determined the elevation classification criteria of the lunar surface.In this paper,we focus on the classification criteria of the topographic relief amplitude of the lunar surface.To estimate the optimal window for calculating the relief amplitude of the lunar surface,we use the mean change-point method based on LOLA(Lunar Orbiter Laser Altimeter)Digital Elevation Model(DEM)data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera(SELENE TC).The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar landforms.Taking the topographic relief amplitudes of 100 m,200 m,300 m,700 m,1500 m and 2500 m as thresholds,the lunar surface is divided into seven geomorphic types,including minor microrelief plains(<100 m),minor microrelief platforms[100 m,200 m),microrelief landforms[200 m,300 m),small relief landforms[300 m,700 m),medium relief landforms[700 m,1500 m),large relief landforms[1500 m,2500 m)and extremely large relief landforms(≥2500 m).The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins,while the minor microrelief platforms are mainly in the transition regions between the maria and highlands.The microrelief landforms are mainly located in regions with relatively high topography,such as wrinkle ridges and sinuous rilles in the mare.The small relief landforms are mainly scattered in the central peak and floor fractures of craters.The medium relief landforms are mainly distributed in the transition regions between crater floors and crater walls,between crater walls and crater rims,between basin floors and basin walls,and between basin walls and basin rims.Large and extremely large relief landforms are mainly found along crater walls and basin walls.The classification criteria determination for assessing lunar surface relief amplitude described in this paper can provide important references for the construction of digital lunar surface geomorphology classification schemes.
基金jointly supported by the National Social Science Foundation in China(Grand No.10ATQ004)Ministry of Education,Humanities and Social Sciences Council in China(Grand No.09YJA870014)
文摘Social network analysis(SNA) has been introduced to China's Mainland since the end of last century. It is often stated that SNA research has experienced rapid growth in China over these years, but few studies have been conducted to prove the statement. This paper aims at exploring the research status and development of SNA in China by a critical assessment of journal articles. Our findings show that SNA is an evolving and diversified research area which has rich themes and topics, and can be applied to those studies on different levels, context and disciplines, and attract researchers and scholars from various fields and domains. In addition, the information community(Library & Information Science and Information Systems) plays a leading role in the SNA related researches. The paper also points out the research on SNA in China has some limitations, so it proposes several implications for the future development of SNA research from perspectives of information science.
文摘Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).
