This paper investigates human mobility patterns in an urban taxi transportation system. This work focuses on predicting human mobility from discovering patterns of in the number of passenger pick-ups quantity （PUQ） ...This paper investigates human mobility patterns in an urban taxi transportation system. This work focuses on predicting human mobility from discovering patterns of in the number of passenger pick-ups quantity （PUQ） from urban hotspots. This paper proposes an improved ARIMA based prediction method to forecast the spatial-temporal variation of passengers in a hotspot. Evaluation with a large-scale real- world data set of 4 000 taxis＇ GPS traces over one year shows a prediction error of only 5.8%. We also explore the applica- tion of the pl^di^fioti approach to help drivers find their next passetlgerS, The sinatllation results using historical real-world data demonstrate that, with our guidance, drivers can reduce the time taken and distance travelled, to find their next pas- senger＋ by 37.1% and 6.4% respectively,展开更多
随着学习科学领域的兴起,深度学习逐渐成为教育领域的核心研究主题。运用基于引文分析与共词聚类分析的方法,以Web of Science数据库2005-2015年收录的459篇文献为研究对象,通过可视化知识图谱,探析近十年来国外深度学习领域的研究现状...随着学习科学领域的兴起,深度学习逐渐成为教育领域的核心研究主题。运用基于引文分析与共词聚类分析的方法,以Web of Science数据库2005-2015年收录的459篇文献为研究对象,通过可视化知识图谱,探析近十年来国外深度学习领域的研究现状与研究热点,并进一步结合国内研究现状提出几点启示,以期对同类研究提供有益的借鉴。展开更多
Biochar is the carbon-rich product obtained from the thermochemical conversion of biomass under oxygen-limited conditions.Biochar has attained extensive attention due to its agronomical and environmental benefits in a...Biochar is the carbon-rich product obtained from the thermochemical conversion of biomass under oxygen-limited conditions.Biochar has attained extensive attention due to its agronomical and environmental benefits in agro-ecosystems.This work adopts the scientometric analysis method to assess the development trends of biochar research based on the literature data retrieved from the Web of Science over the period of 1998-2018.By analysing the basic characteristics of 6934 publications,we found that the number of publications grew rapidly since 2010.Based on a keyword analysis,it is concluded that scholars have had a fundamental recognition of biochar and preliminarily found that biochar application had agronomic and environmental benefits during the period of 1998-2010.The clustering results of keywords in documents published during 2011-2015 showed that the main research hotspots were“biochar production”,“biochar and global climate change”,“soil quality and plant growth”,“organic pollutants removal”,and“heavy metals immobilization”.While in 2016-2018,beside these five main research hotspots,“biochar and composting”topic had also received greater attention,indicating that biochar utilization in organic solid waste composting is the current research hotspot.Moreover,updated reactors(e.g.,microwave reactor,fixed-bed reactor,screw-feeding reactor,bubbling fluidized bed reactor,etc.)or technologies(e.g.,solar pyrolysis,Thermo-Catalytic Reforming process,liquefaction technology,etc.)applied for efficient energy production and modified biochar for environmental remediation have been extensively studied recently.The findings may help the new researchers to seize the research frontier in the biochar field.展开更多
目的通过分析近年来SCI期刊发表的护理缺失相关文献,了解该领域的研究热点和前沿,为以后的研究提供参考。方法在Web of Science核心合集中检索从建库到2021年以护理缺失为主题的文献,利用CiteSpace软件对纳入文献进行可视化分析。结果...目的通过分析近年来SCI期刊发表的护理缺失相关文献,了解该领域的研究热点和前沿,为以后的研究提供参考。方法在Web of Science核心合集中检索从建库到2021年以护理缺失为主题的文献,利用CiteSpace软件对纳入文献进行可视化分析。结果共纳入297篇文献,年发文量呈缓慢增长趋势,美国居世界首位,已形成核心作者群,研究热点主要集中在护理缺失的影响因素、不良结局和相关干预措施等方面。结论当前对于护理缺失的研究还不够全面,鉴于该问题对护士、患者、医院等多方面都会造成重大不良影响,相关研究者和护理管理者应对该问题予以足够的重视,对相关方面展开深入探讨。展开更多
We examined the scale impacts on spatial hot and cold spots of CPUE for Ommastrephes bartramii in the northwest Pacific Ocean. The original fishery data were tessellated to 18 spatial scales from 5′×5′ to 90′&...We examined the scale impacts on spatial hot and cold spots of CPUE for Ommastrephes bartramii in the northwest Pacific Ocean. The original fishery data were tessellated to 18 spatial scales from 5′×5′ to 90′×90′ with a scale interval of 5′ to identify the local clusters. The changes in location, boundaries, and statistics regarding the Getis-Ord Gi＊ hot and cold spots in response to the spatial scales were analyzed in detail. Several statistics including Min, mean, Max, SD, CV, skewness, kurtosis, first quartile（Q1）, median, third quartile（Q3）, area and centroid were calculated for spatial hot and cold spots. Scaling impacts were examined for the selected statistics using linear, logarithmic, exponential, power law and polynomial functions. Clear scaling relations were identified for Max, SD and kurtosis for both hot and cold spots. For the remaining statistics, either a difference of scale impacts was found between the two clusters, or no clear scaling relation was identified. Spatial scales coarser than 30′ are not recommended to identify the local spatial patterns of fisheries because the boundary and locations of hot and cold spots at a coarser scale are significantly different from those at the original scale.展开更多
基金The authors would like to acknowledge financial support by the National Natural Science Foundation(Project No.51701026)the Chongqing Research Program of Basic Research and Frontier Technology(Project No.cstc2018jcyjAX0611)+2 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN201803103)the Fundamental Research Funds for the Central Universities(Project No.2018CDGFCL0005 and Project No.2018CDJDCL0019)the support of the 111 Project(Project No.B 16007)by the Ministry of Education and the State Administration of Foreign Experts Affairs of China.
文摘This paper investigates human mobility patterns in an urban taxi transportation system. This work focuses on predicting human mobility from discovering patterns of in the number of passenger pick-ups quantity （PUQ） from urban hotspots. This paper proposes an improved ARIMA based prediction method to forecast the spatial-temporal variation of passengers in a hotspot. Evaluation with a large-scale real- world data set of 4 000 taxis＇ GPS traces over one year shows a prediction error of only 5.8%. We also explore the applica- tion of the pl^di^fioti approach to help drivers find their next passetlgerS, The sinatllation results using historical real-world data demonstrate that, with our guidance, drivers can reduce the time taken and distance travelled, to find their next pas- senger＋ by 37.1% and 6.4% respectively,
文摘随着学习科学领域的兴起,深度学习逐渐成为教育领域的核心研究主题。运用基于引文分析与共词聚类分析的方法,以Web of Science数据库2005-2015年收录的459篇文献为研究对象,通过可视化知识图谱,探析近十年来国外深度学习领域的研究现状与研究热点,并进一步结合国内研究现状提出几点启示,以期对同类研究提供有益的借鉴。
基金support by the National Natural Science Foundation of China(21537002,41422105,41671478)the Natural Science Foundation of Jiangsu Province,China(Project No.BK20130050).
文摘Biochar is the carbon-rich product obtained from the thermochemical conversion of biomass under oxygen-limited conditions.Biochar has attained extensive attention due to its agronomical and environmental benefits in agro-ecosystems.This work adopts the scientometric analysis method to assess the development trends of biochar research based on the literature data retrieved from the Web of Science over the period of 1998-2018.By analysing the basic characteristics of 6934 publications,we found that the number of publications grew rapidly since 2010.Based on a keyword analysis,it is concluded that scholars have had a fundamental recognition of biochar and preliminarily found that biochar application had agronomic and environmental benefits during the period of 1998-2010.The clustering results of keywords in documents published during 2011-2015 showed that the main research hotspots were“biochar production”,“biochar and global climate change”,“soil quality and plant growth”,“organic pollutants removal”,and“heavy metals immobilization”.While in 2016-2018,beside these five main research hotspots,“biochar and composting”topic had also received greater attention,indicating that biochar utilization in organic solid waste composting is the current research hotspot.Moreover,updated reactors(e.g.,microwave reactor,fixed-bed reactor,screw-feeding reactor,bubbling fluidized bed reactor,etc.)or technologies(e.g.,solar pyrolysis,Thermo-Catalytic Reforming process,liquefaction technology,etc.)applied for efficient energy production and modified biochar for environmental remediation have been extensively studied recently.The findings may help the new researchers to seize the research frontier in the biochar field.
文摘目的通过分析近年来SCI期刊发表的护理缺失相关文献,了解该领域的研究热点和前沿,为以后的研究提供参考。方法在Web of Science核心合集中检索从建库到2021年以护理缺失为主题的文献,利用CiteSpace软件对纳入文献进行可视化分析。结果共纳入297篇文献,年发文量呈缓慢增长趋势,美国居世界首位,已形成核心作者群,研究热点主要集中在护理缺失的影响因素、不良结局和相关干预措施等方面。结论当前对于护理缺失的研究还不够全面,鉴于该问题对护士、患者、医院等多方面都会造成重大不良影响,相关研究者和护理管理者应对该问题予以足够的重视,对相关方面展开深入探讨。
基金The National Natural Science Foundation of China under contract No.41406146the Open Fund from Laboratory for Marine Fisheries Science and Food Production Processes at Qingdao National Laboratory for Marine Science and Technology of China under contract No.2017-1A02Shanghai Universities First-class Disciplines Project-Fisheries(A)
文摘We examined the scale impacts on spatial hot and cold spots of CPUE for Ommastrephes bartramii in the northwest Pacific Ocean. The original fishery data were tessellated to 18 spatial scales from 5′×5′ to 90′×90′ with a scale interval of 5′ to identify the local clusters. The changes in location, boundaries, and statistics regarding the Getis-Ord Gi＊ hot and cold spots in response to the spatial scales were analyzed in detail. Several statistics including Min, mean, Max, SD, CV, skewness, kurtosis, first quartile（Q1）, median, third quartile（Q3）, area and centroid were calculated for spatial hot and cold spots. Scaling impacts were examined for the selected statistics using linear, logarithmic, exponential, power law and polynomial functions. Clear scaling relations were identified for Max, SD and kurtosis for both hot and cold spots. For the remaining statistics, either a difference of scale impacts was found between the two clusters, or no clear scaling relation was identified. Spatial scales coarser than 30′ are not recommended to identify the local spatial patterns of fisheries because the boundary and locations of hot and cold spots at a coarser scale are significantly different from those at the original scale.
