Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated s...Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated significant potential in further enhancing S2S forecasts beyond the capabilities of NWP models.However,most current DLbased S2S forecasting models largely overlook the role of global predictors from multiple spheres,such as ocean,land,and atmosphere domains,that are crucial for effective S2S forecasting.In this study,we introduce EAAC-S2S,a tailored DL model for S2S forecasting of East Asian atmospheric circulation.EAAC-S2S employs the cross-attention mechanism to couple atmospheric circulations over East Asia with representative multi-sphere(i.e.,atmosphere,land,and ocean)variables,providing pentad-averaged circulation forecasts up to 12 pentads ahead throughout all seasons.Experimental results demonstrate,on the S2S time scale,that EAAC-S2S consistently outperforms the European Centre for MediumRange Weather Forecasts(ECMWF)Ensemble Prediction System by decreasing the root-mean-square error(RMSE)by3.8%and increasing the anomaly correlation coefficient(ACC)by 8.6%,averaged across all 17 predictands.Our system also shows good skill for examples of heatwaves and the South China Sea Subtropical High Intensity Index(SCSSHII).Moreover,quantitative interpretability analysis including multi-sphere attribution and attention visualization are conducted for the first time in a DL S2S model,where the traced predictability aligns well with prior meteorological knowledge.We hope that our results have the potential to advance research in data-driven S2S forecasting.展开更多
This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detector...This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detectors embedded in eight polyethylene(PE) spheres of varying diameters. The transport processes of a neutron in the multi-sphere spectrometer are simulated using the Geant4 code. Two sets of response functions of the PE spheres are obtained for calculating the^(241)Am–Be neutron spectrum.Response Function 1 utilizes the thermal neutron scattering model G4 Neutron HPThermal Scattering for neutron energies of ≤4 eV, and Response Function 2 has no thermal treatment. Neutron spectra of an^(241)Am–Be neutron source are measured and compared to those calculated by using the response functions. The results show that response function with thermal treatment is more accurate and closer to the real spectrum.展开更多
In order to realize the on-line real-time measurement of neutron spectrum of ITER fusion,this paper presents a multi-sphere spectrometer system which consists of eight thermal neutron detectors,namely SP9 3He proporti...In order to realize the on-line real-time measurement of neutron spectrum of ITER fusion,this paper presents a multi-sphere spectrometer system which consists of eight thermal neutron detectors,namely SP9 3He proportional counter,embedded in eight different diameter polyethylene spheres.The response function of eight polyethylene spheres of multi-sphere neutron spectrometer was calculated after the simulation of the neutron transport processes in multi-sphere spectrometer by adopting software Geant4.The peak of the response function is in the low energy region for smaller diameter polyethylene sphere.As the polyethylene sphere diameter increased,the peak of the response function moves to the high energy region.The experimental calibration adopts 241Am-Be neutron source.The relative error between normalized data of experiment 4πsolid angle counts and normalized data of simulated detection efficiency of 4in to 8in polyethylene sphere is from 1.152%to 12.222%.The experimental results verify the response function of the simulation.All these results provide a theoretical and experimental basis for solving the on-line real-time neutron spectrum of ITER fusion.展开更多
Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climat...Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climate change,many compound extremes have exhibited increasing frequency and intensity,and shown novel fashions of combinations,posing more pressing demands and tougher challenges to scientific research and disaster prevention and response.This article,via a perspective of multi-sphere interactions within the Earth System,systematically reviews the status quo,new scientific understanding,and deficiencies regarding the definition,mechanism,change,attribution,and projection of compound extremes.This study also sorts out existing challenges and outlines a potential roadmap in advancing the study on compound extremes with respect to data requirement,mechanistic diagnosis,numerical modeling,attribution and projection,risk assessment,and adaptive response.Further directions of compound extremes studies and key research topics that warrant multi-disciplinary and multisectoral coordinated efforts are also proposed.Given that climate change has reshaped the type of extremes,a transformation from the traditional single-event perspective to a compound-event perspective is needed for scientific research,disaster prevention and mitigation,and climate change adaptation,calling for bottom-up innovation in research objects,ideas,and methods.This article will add value to promoting the research on compound extremes and interdisciplinary cooperations.展开更多
In the present study,a combined bonded multi-sphere model was developed,validated,and applied to simulate the motion and breakage behavior of wet fibers in a fluidized bed.The effects of particle resolution,bond numbe...In the present study,a combined bonded multi-sphere model was developed,validated,and applied to simulate the motion and breakage behavior of wet fibers in a fluidized bed.The effects of particle resolution,bond number,and humidity coefficient(γ)on fiber breakage rate,breakage location,and fragment size distribution were systematically investigated.Results show that increasing particle resolution from 3 to 6 generally reduces fiber breakage.While a higher bond number lowers the probability of breakage.Two different breakage modes are identified under varyingγvalues:Mode 1,characterized by breakage due to collisions between rapidly falling individual fibers and fiber clusters,and Mode 2,arising from impacts between fiber clusters and the bed bottom.Asγincreases within a certain range,the dominant breakage mechanism transitions from Mode 1 to a mixed mode involving both Modes 1 and 2,accompanied by a shift in the primary breakage location from the corner region toward the center region of the bed.All these findings provide valuable insights into the dynamics of wet fiber fluidization and offer guidance for optimizing wet fiber breakage behavior in real applications.展开更多
基金supported in part by the Meteorological Joint Funds of the National Natural Science Foundation of China(Grant No.U2142211)by the National Key Research and Development Program of China(Grant No.2020YFA0608002)+4 种基金by the National Natural Science Foundation of China(Grant Nos.42075141 and 42341202)by the China National Postdoctoral Program for Innovative Talents(Grant No.BX20230071)by the National Natural Science Foundation of China for Youth(Grant No.42205191)by the Shanghai Municipal Science and Technology Major Project(Grant No.2021SHZDZX0100)the Fundamental Research Funds for the Central Universities。
文摘Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated significant potential in further enhancing S2S forecasts beyond the capabilities of NWP models.However,most current DLbased S2S forecasting models largely overlook the role of global predictors from multiple spheres,such as ocean,land,and atmosphere domains,that are crucial for effective S2S forecasting.In this study,we introduce EAAC-S2S,a tailored DL model for S2S forecasting of East Asian atmospheric circulation.EAAC-S2S employs the cross-attention mechanism to couple atmospheric circulations over East Asia with representative multi-sphere(i.e.,atmosphere,land,and ocean)variables,providing pentad-averaged circulation forecasts up to 12 pentads ahead throughout all seasons.Experimental results demonstrate,on the S2S time scale,that EAAC-S2S consistently outperforms the European Centre for MediumRange Weather Forecasts(ECMWF)Ensemble Prediction System by decreasing the root-mean-square error(RMSE)by3.8%and increasing the anomaly correlation coefficient(ACC)by 8.6%,averaged across all 17 predictands.Our system also shows good skill for examples of heatwaves and the South China Sea Subtropical High Intensity Index(SCSSHII).Moreover,quantitative interpretability analysis including multi-sphere attribution and attention visualization are conducted for the first time in a DL S2S model,where the traced predictability aligns well with prior meteorological knowledge.We hope that our results have the potential to advance research in data-driven S2S forecasting.
基金supported by ITER Plan National Major Project(No.2008GB109000)the Introduces Talents Scientific Research Project of Guizhou University(2014,No.32)
文摘This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detectors embedded in eight polyethylene(PE) spheres of varying diameters. The transport processes of a neutron in the multi-sphere spectrometer are simulated using the Geant4 code. Two sets of response functions of the PE spheres are obtained for calculating the^(241)Am–Be neutron spectrum.Response Function 1 utilizes the thermal neutron scattering model G4 Neutron HPThermal Scattering for neutron energies of ≤4 eV, and Response Function 2 has no thermal treatment. Neutron spectra of an^(241)Am–Be neutron source are measured and compared to those calculated by using the response functions. The results show that response function with thermal treatment is more accurate and closer to the real spectrum.
基金Supported by ITER Plan National Major Project 2008GB109000
文摘In order to realize the on-line real-time measurement of neutron spectrum of ITER fusion,this paper presents a multi-sphere spectrometer system which consists of eight thermal neutron detectors,namely SP9 3He proportional counter,embedded in eight different diameter polyethylene spheres.The response function of eight polyethylene spheres of multi-sphere neutron spectrometer was calculated after the simulation of the neutron transport processes in multi-sphere spectrometer by adopting software Geant4.The peak of the response function is in the low energy region for smaller diameter polyethylene sphere.As the polyethylene sphere diameter increased,the peak of the response function moves to the high energy region.The experimental calibration adopts 241Am-Be neutron source.The relative error between normalized data of experiment 4πsolid angle counts and normalized data of simulated detection efficiency of 4in to 8in polyethylene sphere is from 1.152%to 12.222%.The experimental results verify the response function of the simulation.All these results provide a theoretical and experimental basis for solving the on-line real-time neutron spectrum of ITER fusion.
基金supported by the National Natural Science Foundation of China(Grant No.42271024)the Science&Technology Development Funding of Chinese Academy of Meteorological Sciences(Grant No.2023KJ015)。
文摘Compound extremes,whose socioeconomic and ecological impacts are severer than that caused by each event occurring in isolation,have evolved into a hot topic in Earth Science in the past decade.In the context of climate change,many compound extremes have exhibited increasing frequency and intensity,and shown novel fashions of combinations,posing more pressing demands and tougher challenges to scientific research and disaster prevention and response.This article,via a perspective of multi-sphere interactions within the Earth System,systematically reviews the status quo,new scientific understanding,and deficiencies regarding the definition,mechanism,change,attribution,and projection of compound extremes.This study also sorts out existing challenges and outlines a potential roadmap in advancing the study on compound extremes with respect to data requirement,mechanistic diagnosis,numerical modeling,attribution and projection,risk assessment,and adaptive response.Further directions of compound extremes studies and key research topics that warrant multi-disciplinary and multisectoral coordinated efforts are also proposed.Given that climate change has reshaped the type of extremes,a transformation from the traditional single-event perspective to a compound-event perspective is needed for scientific research,disaster prevention and mitigation,and climate change adaptation,calling for bottom-up innovation in research objects,ideas,and methods.This article will add value to promoting the research on compound extremes and interdisciplinary cooperations.
文摘In the present study,a combined bonded multi-sphere model was developed,validated,and applied to simulate the motion and breakage behavior of wet fibers in a fluidized bed.The effects of particle resolution,bond number,and humidity coefficient(γ)on fiber breakage rate,breakage location,and fragment size distribution were systematically investigated.Results show that increasing particle resolution from 3 to 6 generally reduces fiber breakage.While a higher bond number lowers the probability of breakage.Two different breakage modes are identified under varyingγvalues:Mode 1,characterized by breakage due to collisions between rapidly falling individual fibers and fiber clusters,and Mode 2,arising from impacts between fiber clusters and the bed bottom.Asγincreases within a certain range,the dominant breakage mechanism transitions from Mode 1 to a mixed mode involving both Modes 1 and 2,accompanied by a shift in the primary breakage location from the corner region toward the center region of the bed.All these findings provide valuable insights into the dynamics of wet fiber fluidization and offer guidance for optimizing wet fiber breakage behavior in real applications.
