Purpose:Research dynamics have long been a research interest.It is a macro perspective tool for discovering temporal research trends of a certain discipline or subject.A micro perspective of research dynamics,however,...Purpose:Research dynamics have long been a research interest.It is a macro perspective tool for discovering temporal research trends of a certain discipline or subject.A micro perspective of research dynamics,however,concerning a single researcher or a highly cited paper in terms of their citations and“citations of citations”(forward chaining)remains unexplored.Design/methodology/approach:In this paper,we use a cross-collection topic model to reveal the research dynamics of topic disappearance topic inheritance,and topic innovation in each generation of forward chaining.Findings:For highly cited work,scientific influence exists in indirect citations.Topic modeling can reveal how long this influence exists in forward chaining,as well as its influence.Research limitations:This paper measures scientific influence and indirect scientific influence only if the relevant words or phrases are borrowed or used in direct or indirect citations.Paraphrasing or semantically similar concept may be neglected in this research.Practical implications:This paper demonstrates that a scientific influence exists in indirect citations through its analysis of forward chaining.This can serve as an inspiration on how to adequately evaluate research influence.Originality:The main contributions of this paper are the following three aspects.First,besides research dynamics of topic inheritance and topic innovation,we model topic disappearance by using a cross-collection topic model.Second,we explore the length and character of the research impact through“citations of citations”content analysis.Finally,we analyze the research dynamics of artificial intelligence researcher Geoffrey Hinton’s publications and the topic dynamics of forward chaining.展开更多
This paper is a further study of reference [1]. In this paper, we mainly discuss the complicated dynamical behaviors resulting from a simple one-dimensional model of nonlinear ecosystems: fixed point motion, periodic ...This paper is a further study of reference [1]. In this paper, we mainly discuss the complicated dynamical behaviors resulting from a simple one-dimensional model of nonlinear ecosystems: fixed point motion, periodic motion and chaotic motion etc., and briefly discuss the universality of the complicated dynamical behaviors, which can be described by the first and the second M. Feigenbaun. constants. At last, we discuss the 'one-side lowering phenomenon' due to near unstabilization when the nonlinear ecosystem approaches bifurcation points from unbifurcation side. It is of important theoretical and practical meanings both in the development and utilization of ecological resources ar.d in the design and management of artifilial ecosystems.展开更多
Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fie...Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fields. In order to better evaluate the speckle, speckle measurement methods must be studied. In this study, a dynamic measurement method for laser speckles is proposed according to the optical superposition characteristics of speckle, which can reduce the influence of non-coherent factors on the speckle measurement results. The feasibility of the dynamic speckle measurement method is verified by designing an experimental scheme.展开更多
Purpose–With the yearly increase of mileage and passenger volume in China’s high-speed railway,the problems of traditional paper railway tickets have become increasingly prominent,including complexity of business ha...Purpose–With the yearly increase of mileage and passenger volume in China’s high-speed railway,the problems of traditional paper railway tickets have become increasingly prominent,including complexity of business handling process,low efficiency of ticket inspection and high cost of usage and management.This paper aims to make extensive references to successful experiences of electronic ticket applications both domestically and internationally.The research on key technologies and system implementation of railway electronic ticket with Chinese characteristics has been carried out.Design/methodology/approach–Research in key technologies is conducted including synchronization technique in distributed heterogeneous database system,the grid-oriented passenger service record(PSR)data storage model,efficient access to massive PSR data under high concurrency condition,the linkage between face recognition service platforms and various terminals in large scenarios,and two-factor authentication of the e-ticket identification code based on the key and the user identity information.Focusing on the key technologies and architecture the of existing ticketing system,multiple service resources are expanded and developed such as electronic ticket clusters,PSR clusters,face recognition clusters and electronic ticket identification code clusters.Findings–The proportion of paper ticket printed has dropped to 20%,saving more than 2 billion tickets annually since the launch of the application of E-ticketing nationwide.The average time for passengers to pass through the automatic ticket gates has decreased from 3 seconds to 1.3 seconds,significantly improving the efficiency of passenger transport organization.Meanwhile,problems of paper ticket counterfeiting,reselling and loss have been generally eliminated.Originality/value–E-ticketing has laid a technical foundation for the further development of railway passenger transport services in the direction of digitalization and intelligence.展开更多
The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessm...The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessments. Weather research and forecasting model (WRF) is a nextgeneration, fully compressible, Euler non-hydrostatic mesoscale forecast model with a runtime hydrostatic option. This model is useful for downscaling weather and climate at the scales from one kilometer to thousands of kilometers, and is useful for deriving meteorological parameters required for hydrological simulation too. The objective of this paper is to validate WRF simulating 5 km/ 1 h air temperatures by daily observed data of China Meteorological Administration (CMA) stations, and by hourly in-situ data of the Watershed Allied Telemetry Experimental Research Project. The daily validation shows that the WRF simulation has good agreement with the observed data; the R2 between the WRF simulation and each station is more than 0.93; the absolute of meanbias error (MBE) for each station is less than 2℃; and the MBEs of Ejina, Mazongshan and Alxa stations are near zero, with R2 is more than 0.98, which can be taken as an unbiased estimation. The hourly validation shows that the WRF simulation can capture the basic trend of observed data, the MBE of each site is approximately 2℃, the R2 of each site is more than 0.80, with the highest at 0.95, and the computed and observed surface air temperature series show a significantly similar trend.展开更多
The scientific literature presents a modest amount ot evidence m the use or complementary ana al[erna- tire medicine (CAM). On the other hand, in practice, relevant results are common. The debates among CAM practiti...The scientific literature presents a modest amount ot evidence m the use or complementary ana al[erna- tire medicine (CAM). On the other hand, in practice, relevant results are common. The debates among CAM practitioners about the quality and execution of scientific research are important, Therefore, the aim of this review is to gather, synthesize and describe the differentiated methodological models that encompass the complexity of therapeutic interventions. The process of bringing evidence-based medicine into clinical practice in CAM is essential for the growth and strengthening of complementary medicines worldwide.展开更多
Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle e...Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle efficiency,compact system structures,and chemical stability.The objective of this review is to provide a comprehensive understanding of the helium-xenon Brayton cycle system based on the projects and researches.First,the basic information and development history are introduced,and a series of typical designs are summarized.Then,the system configurations,cycle parameter analysis and optimization are discussed.Next,the key components are classified,such as turbine,compressor,and heat exchanger.Moreover,the dynamic processes and control strategies are introduced in different conditions.Finally,the deficiency and prospect of current research are presented.The review covers the representative helium-xenon Brayton cycle systems,which could provide a reference for promoting the development of energy conversion systems.展开更多
The effects of different Planetary Boundary Layer(PBL) structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computa...The effects of different Planetary Boundary Layer(PBL) structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computational Fluid Dynamics(CFD) model. The boundary conditions of different PBL structures/conditions were provided by simulations of the Weather Researching and Forecasting model. The simulated results of the idealized 2D and 3D street canyon experiments showed that the increment of PBL instability favored the downward transport of momentum from the upper flow above the roof to the pedestrian level within the street canyon. As a result, the flow and turbulent fields within the street canyon under the more unstable PBL condition are stronger. Therefore, more pollutants within the street canyon would be removed by the stronger advection and turbulent diffusion processes under the unstable PBL condition. On the contrary, more pollutants would be concentrated in the street canyon under the stable PBL condition. In addition, the simulations of the realistic building cluster experiments showed that the density of buildings was a crucial factor determining the dynamic effects of the PBL structure on the flow patterns. The momentum field within a denser building configuration was mostly transported from the upper flow, and was more sensitive to the PBL structures than that of the sparser building configuration. Finally, it was recommended to use the Mellor-Yamada-Nakanishi-Niino(MYNN) PBL scheme, which can explicitly output the needed turbulent variables, to provide the boundary conditions to the CFD simulation.展开更多
基金This work is supported by the Programs for the Young Talents of National Science Library,Chinese Academy of Sciences(Grant No.2019QNGR003).
文摘Purpose:Research dynamics have long been a research interest.It is a macro perspective tool for discovering temporal research trends of a certain discipline or subject.A micro perspective of research dynamics,however,concerning a single researcher or a highly cited paper in terms of their citations and“citations of citations”(forward chaining)remains unexplored.Design/methodology/approach:In this paper,we use a cross-collection topic model to reveal the research dynamics of topic disappearance topic inheritance,and topic innovation in each generation of forward chaining.Findings:For highly cited work,scientific influence exists in indirect citations.Topic modeling can reveal how long this influence exists in forward chaining,as well as its influence.Research limitations:This paper measures scientific influence and indirect scientific influence only if the relevant words or phrases are borrowed or used in direct or indirect citations.Paraphrasing or semantically similar concept may be neglected in this research.Practical implications:This paper demonstrates that a scientific influence exists in indirect citations through its analysis of forward chaining.This can serve as an inspiration on how to adequately evaluate research influence.Originality:The main contributions of this paper are the following three aspects.First,besides research dynamics of topic inheritance and topic innovation,we model topic disappearance by using a cross-collection topic model.Second,we explore the length and character of the research impact through“citations of citations”content analysis.Finally,we analyze the research dynamics of artificial intelligence researcher Geoffrey Hinton’s publications and the topic dynamics of forward chaining.
基金Supported by the Youth Science Fundation of Chinese Academia SinicaYouth Fundation of Lanzhou Unviersity
文摘This paper is a further study of reference [1]. In this paper, we mainly discuss the complicated dynamical behaviors resulting from a simple one-dimensional model of nonlinear ecosystems: fixed point motion, periodic motion and chaotic motion etc., and briefly discuss the universality of the complicated dynamical behaviors, which can be described by the first and the second M. Feigenbaun. constants. At last, we discuss the 'one-side lowering phenomenon' due to near unstabilization when the nonlinear ecosystem approaches bifurcation points from unbifurcation side. It is of important theoretical and practical meanings both in the development and utilization of ecological resources ar.d in the design and management of artifilial ecosystems.
基金supported by the National Natural Science Foundation of China (No.62076160)the Natural Science Foundation of Shanghai (No.21ZR1424700)。
文摘Laser display technology is the most promising display technology in the market and is widely used in many fields. However, laser speckle has been troubling the application and expansion of this technology in some fields. In order to better evaluate the speckle, speckle measurement methods must be studied. In this study, a dynamic measurement method for laser speckles is proposed according to the optical superposition characteristics of speckle, which can reduce the influence of non-coherent factors on the speckle measurement results. The feasibility of the dynamic speckle measurement method is verified by designing an experimental scheme.
基金supported by the National Key R&D Program of China(No.2020YFF0304101).
文摘Purpose–With the yearly increase of mileage and passenger volume in China’s high-speed railway,the problems of traditional paper railway tickets have become increasingly prominent,including complexity of business handling process,low efficiency of ticket inspection and high cost of usage and management.This paper aims to make extensive references to successful experiences of electronic ticket applications both domestically and internationally.The research on key technologies and system implementation of railway electronic ticket with Chinese characteristics has been carried out.Design/methodology/approach–Research in key technologies is conducted including synchronization technique in distributed heterogeneous database system,the grid-oriented passenger service record(PSR)data storage model,efficient access to massive PSR data under high concurrency condition,the linkage between face recognition service platforms and various terminals in large scenarios,and two-factor authentication of the e-ticket identification code based on the key and the user identity information.Focusing on the key technologies and architecture the of existing ticketing system,multiple service resources are expanded and developed such as electronic ticket clusters,PSR clusters,face recognition clusters and electronic ticket identification code clusters.Findings–The proportion of paper ticket printed has dropped to 20%,saving more than 2 billion tickets annually since the launch of the application of E-ticketing nationwide.The average time for passengers to pass through the automatic ticket gates has decreased from 3 seconds to 1.3 seconds,significantly improving the efficiency of passenger transport organization.Meanwhile,problems of paper ticket counterfeiting,reselling and loss have been generally eliminated.Originality/value–E-ticketing has laid a technical foundation for the further development of railway passenger transport services in the direction of digitalization and intelligence.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant Nos. 40901202, 40925004), and the National High Technology Research and Development Program of China (Grant No. 2009AA122104). The input data for WRF model are from the Research Data Archive (RDA) which is maintained by the Computational and Information Systems Laboratory (CISL) at the National Center for Atmo- spheric Research (NCAR). The original data are available from the RDA (http://dss.ucar.edu) in Dataset No. ds083.2.
文摘The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessments. Weather research and forecasting model (WRF) is a nextgeneration, fully compressible, Euler non-hydrostatic mesoscale forecast model with a runtime hydrostatic option. This model is useful for downscaling weather and climate at the scales from one kilometer to thousands of kilometers, and is useful for deriving meteorological parameters required for hydrological simulation too. The objective of this paper is to validate WRF simulating 5 km/ 1 h air temperatures by daily observed data of China Meteorological Administration (CMA) stations, and by hourly in-situ data of the Watershed Allied Telemetry Experimental Research Project. The daily validation shows that the WRF simulation has good agreement with the observed data; the R2 between the WRF simulation and each station is more than 0.93; the absolute of meanbias error (MBE) for each station is less than 2℃; and the MBEs of Ejina, Mazongshan and Alxa stations are near zero, with R2 is more than 0.98, which can be taken as an unbiased estimation. The hourly validation shows that the WRF simulation can capture the basic trend of observed data, the MBE of each site is approximately 2℃, the R2 of each site is more than 0.80, with the highest at 0.95, and the computed and observed surface air temperature series show a significantly similar trend.
文摘The scientific literature presents a modest amount ot evidence m the use or complementary ana al[erna- tire medicine (CAM). On the other hand, in practice, relevant results are common. The debates among CAM practitioners about the quality and execution of scientific research are important, Therefore, the aim of this review is to gather, synthesize and describe the differentiated methodological models that encompass the complexity of therapeutic interventions. The process of bringing evidence-based medicine into clinical practice in CAM is essential for the growth and strengthening of complementary medicines worldwide.
基金supported by the Innovative Scientific Program of China National Nuclear Corporation(XYYLC202104)。
文摘Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle efficiency,compact system structures,and chemical stability.The objective of this review is to provide a comprehensive understanding of the helium-xenon Brayton cycle system based on the projects and researches.First,the basic information and development history are introduced,and a series of typical designs are summarized.Then,the system configurations,cycle parameter analysis and optimization are discussed.Next,the key components are classified,such as turbine,compressor,and heat exchanger.Moreover,the dynamic processes and control strategies are introduced in different conditions.Finally,the deficiency and prospect of current research are presented.The review covers the representative helium-xenon Brayton cycle systems,which could provide a reference for promoting the development of energy conversion systems.
基金supported by the China Meteorological Administration Special Public Welfare Research Fund (No. GYHY201106033)the National Natural Science Foundation of China (No. 41175004)
文摘The effects of different Planetary Boundary Layer(PBL) structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computational Fluid Dynamics(CFD) model. The boundary conditions of different PBL structures/conditions were provided by simulations of the Weather Researching and Forecasting model. The simulated results of the idealized 2D and 3D street canyon experiments showed that the increment of PBL instability favored the downward transport of momentum from the upper flow above the roof to the pedestrian level within the street canyon. As a result, the flow and turbulent fields within the street canyon under the more unstable PBL condition are stronger. Therefore, more pollutants within the street canyon would be removed by the stronger advection and turbulent diffusion processes under the unstable PBL condition. On the contrary, more pollutants would be concentrated in the street canyon under the stable PBL condition. In addition, the simulations of the realistic building cluster experiments showed that the density of buildings was a crucial factor determining the dynamic effects of the PBL structure on the flow patterns. The momentum field within a denser building configuration was mostly transported from the upper flow, and was more sensitive to the PBL structures than that of the sparser building configuration. Finally, it was recommended to use the Mellor-Yamada-Nakanishi-Niino(MYNN) PBL scheme, which can explicitly output the needed turbulent variables, to provide the boundary conditions to the CFD simulation.