Uncertainty is common in the life cycle of an aircraft, and Robust Aerodynamic Optimization(RAO) that considers uncertainty is important in aircraft design. To avoid the curse of dimensionality in surrogate-based opti...Uncertainty is common in the life cycle of an aircraft, and Robust Aerodynamic Optimization(RAO) that considers uncertainty is important in aircraft design. To avoid the curse of dimensionality in surrogate-based optimization, this study proposes an adjoint RAO technique called “R-Opt”. Polynomial Chaos Expansion(PCE) is coupled with the R-Opt technique to quantify uncertainty in the responses of the target(including its mean and standard deviation). Only one process of PCE model construction is required in each iteration, and the gradients of uncertainty can be inferred via chain rules. The proposed method is more efficient than prevalent methods,and avoids the problem of a disagreement over the best PCE basis from among a number of PCE models(especially in case of sparse PCE). It also supports the application of sparse PCE.Two benchmark tests and two airfoil cases were used to verify R-Opt, and the optimal solutions were deemed to be robust. It improved the mean aerodynamic performance and reduced the standard deviation of the target.展开更多
Nitrous acid(HONO)is a crucial source of OH radicals in the troposphere,significantly enhancing secondary pollutants like secondary organic aerosols(SOA)and peroxyacetyl nitrates(PAN).While prior research has examined...Nitrous acid(HONO)is a crucial source of OH radicals in the troposphere,significantly enhancing secondary pollutants like secondary organic aerosols(SOA)and peroxyacetyl nitrates(PAN).While prior research has examined HONO sources and their total impacts on secondary pollution,the specific enhancement capacity of each individual HONO source remains underexplored.This study uses observational data from 2015 to 2018 for HONO,SOA,and PAN across six sites in China,combined with WRF-Chem model adding six potential HONO sources to evaluate their capacity:traffic emissions(E_traffic),soil emissions(E_soil),indoor-outdoor exchange(E_indoor),nitrate photolysis(P_nit),and NO_(2) heterogeneous reactions on aerosol and ground surfaces(Het_a,Het_g).The simulated HONO contributions near the ground in urban Beijing were:12%from NO+OH(default source),10%-20%from E_traffic,1%-12%from P_nit,2%-10%from Het_a,and 50%-70% from Het_g.For SOA and PAN,we calculated incremental contributions enhanced by each HONO source and derived enhancement ratios(ERs)normalized against HONO’s contribution:~7 for P_nit,~2 for Het_a,~0.9 for Het_g,~0.8 for E_soil,~0.3 for E_traffic,and~0.1 for E_indoor.HONO sources’capacity to enhance secondary pollutants varies,being larger for aerosol-related sources.Vertical analysis on HONO concentration,spatial distribution,RO_(x) radical cycling rates,and OH enhancements revealed that aerosol-related HONO sources,especially P_nit,contribute more to secondary pollution.Future research should focus more on assessing real-world impacts of HONO sources,besides identifying their budgets.Additionally,uptake coefficient(γ)and nitrate photolysis frequency(J_(nitrate))critically affect HONO and secondary pollutant formation,necessitating further investigations.展开更多
Investigating the spatiotemporal evolution of vegetation and its response mechanisms to natural and anthropogenic elements is crucial for regional vegetation restoration and ecological preservation.The Mu Us Sandy Lan...Investigating the spatiotemporal evolution of vegetation and its response mechanisms to natural and anthropogenic elements is crucial for regional vegetation restoration and ecological preservation.The Mu Us Sandy Land(MUSL),which is situated in the semi-arid zone of northwestern China adjacent to the Loess Plateau,has been at the forefront of desertification and oasis formation over the past two millennia.This study is based on the synthesis of the Normalized Difference Vegetation Index(NDVI)data from MOD13A3 data in the MODIS(Moderate-Resolution Imaging Spectroradiometer)dataset(2002-2021)and climate data(temperature and precipitation)at annual and monthly scales from the National Earth System Science Data Center.A range of analytical methods,including univariate linear regression,Theil-Sen trend analysis and Mann-Kendall significance test,correlation analysis,residual analysis,and Hurst index,were used to explore the response mechanisms of the NDVI to climate change and human activities and to predict the future trends of the NDVI in the MUSL.The results showed that through the method of correlation analysis,in terms of both spatially averaged correlation coefficients and area proportion,the NDVI was positively correlated with temperature and precipitation in 97.59%and 96.51%of the study area,respectively,indicating that temperature has a greater impact on the NDVI than precipitation.Residual analysis quantified the contributions of climate change and human activities to the NDVI changes,revealing that climate change and human activities contribute up to 30.00%and 70.00%,respectively,suggesting that human activities predominantly affect the NDVI changes in the MUSL.The Hurst index was used to categorize the future trend of the NDVI into four main directions of development:continuous degradation(0.05%of the study area),degradation in the past but improvement in the future(54.45%),improvement in the past but degradation in the future(0.13%),and continuous improvement(45.36%).In more than 50.00%of the regions that have been degraded in the past but were expected to improve in the future,the NDVI was expected to exhibit a stable trend of anti-persistent improvement.These findings provide theoretical support for future ecological protection,planning,and the implementation of ecological engineering in the MUSL,and also offer a theoretical basis for the planning and execution of construction projects,environmental protection measures,and the sustainable development of vegetation.展开更多
To address the early separation problem in the Menter Shear-Stress Transport(SST)turbulence model,a correction for the Turbulent Kinetic Energy(TKE)production term,P_(k),is introduced to account for the effect of the ...To address the early separation problem in the Menter Shear-Stress Transport(SST)turbulence model,a correction for the Turbulent Kinetic Energy(TKE)production term,P_(k),is introduced to account for the effect of the Adverse Pressure Gradient(APG).The correction is determined based on the distribution of Pkin the APG region before separation.When the friction coefficient C_(f) is decomposed,its direct dependence on Pkis clearly observed.However,with the introduction of Bradshaw’s assumption,Pkin the SST turbulence model is over-suppressed,resulting in a lower inner peak or no significant inner peak distribution at all.To address this problem,this paper proposes a Gaussian function,HGauss,which corrects the numerical values of P_(k) involved in the calculation of the Menter SST model by focusing on the inner peak region of P_(k).The modified SST model is then applied to four cases with APGs.The modification leads to an increase in the wall friction coefficient C_(f)in the APG region and causes a downstream shift in the separation location,improving the model’s consistency with high-accuracy data and experimental results.It is demonstrated that this correction can improve the early separation problem in the Menter SST turbulence model.展开更多
Gaze estimation,a crucial non-verbal communication cue,has achieved remarkable progress through convolutional neural networks.However,accurate gaze prediction in uncon-strained environments,particularly in extreme hea...Gaze estimation,a crucial non-verbal communication cue,has achieved remarkable progress through convolutional neural networks.However,accurate gaze prediction in uncon-strained environments,particularly in extreme head poses,partial occlusions,and abnormal lighting,remains challenging.Existing models often struggle to effectively focus on discriminative ocular features,leading to suboptimal performance.To address these limitations,this paper proposes dual-branch gaze estimation with Gaussian mixture distribution heatmaps and dynamic adaptive loss function(DMGDL),a novel dual-branch gaze estimation algorithm.By introducing Gaussian mixture distribution heatmaps centered on pupil positions as spatial attention guides,the model is enabled to prioritize ocular regions.Additionally,a dual-branch network architecture is designed to separately extract features for yaw and pitch angles,enhancing flexibility and mitigating cross-angle interference.A dynamic adaptive loss function is further formulated to address discontinuities in angle estimation,improving robustness and convergence stability.Experimental evaluations on three benchmark datasets demonstrate that DMGDL outperforms state-of-the-art methods,achiev-ing a mean angular error of 3.98°on the Max-Planck institute for informatics face gaze(MPI-IFaceGaze)dataset,10.21°on the physically unconstrained gaze estimation in the wild(Gaze360)dataset and 6.14°on the real-time eye gaze estimation in natural environments(RT-Gene)dataset,exhibiting superior generalization and robustness.展开更多
Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of un...Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of unsteady flows.To enhance computational efficiency,we propose the Implicit-Explicit Two-Step Runge-Kutta(IMEX-TSRK)time-stepping discretization methods for unsteady flows,and develop a novel adaptive algorithm that correctly partitions spatial regions to apply implicit or explicit methods.The novel adaptive IMEX-TSRK schemes effectively handle the numerical stiffness of the small grid size and improve computational efficiency.Compared to implicit and explicit Runge-Kutta(RK)schemes,the IMEX-TSRK methods achieve the same order of accuracy with fewer first derivative calculations.Numerical case tests demonstrate that the IMEX-TSRK methods maintain numerical stability while enhancing computational efficiency.Specifically,in high Reynolds number flows,the computational efficiency of the IMEX-TSRK methods surpasses that of explicit RK schemes by more than one order of magnitude,and that of implicit RK schemes several times over.展开更多
Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are ...Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.展开更多
Although organic compounds are considered to be promising electrode materials with their remarkable characteristics such as diverse structures,design controllability,and environmental friendliness,their low charge-tra...Although organic compounds are considered to be promising electrode materials with their remarkable characteristics such as diverse structures,design controllability,and environmental friendliness,their low charge-transfer capability and limited cycling durability hinder their application in aqueous proton batteries.Herein,we prepared a noncovalent phenazine-based graphene aerogel(H/G)composite for aqueous proton storage,which is realized by redox-active Hexaazatrinaphthalene(HATN)organic compound combined with conductive reduced graphene oxide(rGO).The integration of rGO into HATN not only effectively optimizes the electronic structure of the H/G composite to enhance its electrochemical activity,but also the favorable noncovalent π-π interaction existed between HATN and rGO provides a stable structure for fast electron transportation.The obvious electron transfer in the aerogel composite promotes fast and reversible redox reactions occurred with the imino-active HATN in the composite electrode for proton uptake/removal in an aqueous acidic electrolyte,which are demonstrated by in-situ Fourier transform infrared(FTIR)investigation,theoretical calculations and experimental measurements.Therefore,it can deliver a fast,stable and efficient aqueous proton storage behavior with a large specific capacity of 274 mA·h·g^(-1) and considerable calendar life with~100%capacity retention after 3000 cycles,surpassing previously reported proton-based organic electrodes in aqueous acidic electrolytes.Furthermore,an outstanding soft-package aqueous proton(APB)has been fabricated with considerable long-term cycling stability.展开更多
The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to inv...The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.展开更多
Accurate identification and viability assessment of the parathyroid glands(PGs)are critical when performing thyroid and parathyroid surgeries.Traditional visual inspection-based intrao-perative methods suffer from sub...Accurate identification and viability assessment of the parathyroid glands(PGs)are critical when performing thyroid and parathyroid surgeries.Traditional visual inspection-based intrao-perative methods suffer from subjectivity and uncertainty.Near-infrared(NIR)imaging meth-ods,including NIR autofluorescence(NIRAF)imaging and indocyanine green fluorescence imaging(ICGFI),have emerged as promising and reliable techniques for intraoperative PG identification and assessment.Here,the principles and clinical performanoe of NIR imaging methods were comprehensively reviewed.展开更多
We present the approaches to implementing the k-√k L turbulence model within the framework of the high-order discontinuous Galerkin(DG)method.We use the DG discretization to solve the full Reynolds-averaged Navier-St...We present the approaches to implementing the k-√k L turbulence model within the framework of the high-order discontinuous Galerkin(DG)method.We use the DG discretization to solve the full Reynolds-averaged Navier-Stokes equations.In order to enhance the robustness of approaches,some effective techniques are designed.The HWENO(Hermite weighted essentially non-oscillatory)limiting strategy is adopted for stabilizing the turbulence model variable k.Modifications have been made to the model equation itself by using the auxiliary variable that is always positive.The 2nd-order derivatives of velocities required in computing the von Karman length scale are evaluated in a way to maintain the compactness of DG methods.Numerical results demonstrate that the approaches have achieved the desirable accuracy for both steady and unsteady turbulent simulations.展开更多
基金National Natural Science Foundation of China(No.11721202)。
文摘Uncertainty is common in the life cycle of an aircraft, and Robust Aerodynamic Optimization(RAO) that considers uncertainty is important in aircraft design. To avoid the curse of dimensionality in surrogate-based optimization, this study proposes an adjoint RAO technique called “R-Opt”. Polynomial Chaos Expansion(PCE) is coupled with the R-Opt technique to quantify uncertainty in the responses of the target(including its mean and standard deviation). Only one process of PCE model construction is required in each iteration, and the gradients of uncertainty can be inferred via chain rules. The proposed method is more efficient than prevalent methods,and avoids the problem of a disagreement over the best PCE basis from among a number of PCE models(especially in case of sparse PCE). It also supports the application of sparse PCE.Two benchmark tests and two airfoil cases were used to verify R-Opt, and the optimal solutions were deemed to be robust. It improved the mean aerodynamic performance and reduced the standard deviation of the target.
基金supported by the National Natural Science Foundation of China(Nos.92044302,42075108,42107124,41822703,91544221,91844301,and 22222610)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202011)the Natural Science Foundation of Yunnan Province(No.202302AN360006)。
文摘Nitrous acid(HONO)is a crucial source of OH radicals in the troposphere,significantly enhancing secondary pollutants like secondary organic aerosols(SOA)and peroxyacetyl nitrates(PAN).While prior research has examined HONO sources and their total impacts on secondary pollution,the specific enhancement capacity of each individual HONO source remains underexplored.This study uses observational data from 2015 to 2018 for HONO,SOA,and PAN across six sites in China,combined with WRF-Chem model adding six potential HONO sources to evaluate their capacity:traffic emissions(E_traffic),soil emissions(E_soil),indoor-outdoor exchange(E_indoor),nitrate photolysis(P_nit),and NO_(2) heterogeneous reactions on aerosol and ground surfaces(Het_a,Het_g).The simulated HONO contributions near the ground in urban Beijing were:12%from NO+OH(default source),10%-20%from E_traffic,1%-12%from P_nit,2%-10%from Het_a,and 50%-70% from Het_g.For SOA and PAN,we calculated incremental contributions enhanced by each HONO source and derived enhancement ratios(ERs)normalized against HONO’s contribution:~7 for P_nit,~2 for Het_a,~0.9 for Het_g,~0.8 for E_soil,~0.3 for E_traffic,and~0.1 for E_indoor.HONO sources’capacity to enhance secondary pollutants varies,being larger for aerosol-related sources.Vertical analysis on HONO concentration,spatial distribution,RO_(x) radical cycling rates,and OH enhancements revealed that aerosol-related HONO sources,especially P_nit,contribute more to secondary pollution.Future research should focus more on assessing real-world impacts of HONO sources,besides identifying their budgets.Additionally,uptake coefficient(γ)and nitrate photolysis frequency(J_(nitrate))critically affect HONO and secondary pollutant formation,necessitating further investigations.
基金funded by the Shaanxi Provincial Department of Science and Technology(2023JCYB449)the Yan'an University Project(YDBK2017-19)+1 种基金the Yan'an Science and Technology Bureau's List System Project(2023SLJBZ002)the Shaanxi Provincial Department of Education Natural Science Special Project(23JK0725,24JK0716).
文摘Investigating the spatiotemporal evolution of vegetation and its response mechanisms to natural and anthropogenic elements is crucial for regional vegetation restoration and ecological preservation.The Mu Us Sandy Land(MUSL),which is situated in the semi-arid zone of northwestern China adjacent to the Loess Plateau,has been at the forefront of desertification and oasis formation over the past two millennia.This study is based on the synthesis of the Normalized Difference Vegetation Index(NDVI)data from MOD13A3 data in the MODIS(Moderate-Resolution Imaging Spectroradiometer)dataset(2002-2021)and climate data(temperature and precipitation)at annual and monthly scales from the National Earth System Science Data Center.A range of analytical methods,including univariate linear regression,Theil-Sen trend analysis and Mann-Kendall significance test,correlation analysis,residual analysis,and Hurst index,were used to explore the response mechanisms of the NDVI to climate change and human activities and to predict the future trends of the NDVI in the MUSL.The results showed that through the method of correlation analysis,in terms of both spatially averaged correlation coefficients and area proportion,the NDVI was positively correlated with temperature and precipitation in 97.59%and 96.51%of the study area,respectively,indicating that temperature has a greater impact on the NDVI than precipitation.Residual analysis quantified the contributions of climate change and human activities to the NDVI changes,revealing that climate change and human activities contribute up to 30.00%and 70.00%,respectively,suggesting that human activities predominantly affect the NDVI changes in the MUSL.The Hurst index was used to categorize the future trend of the NDVI into four main directions of development:continuous degradation(0.05%of the study area),degradation in the past but improvement in the future(54.45%),improvement in the past but degradation in the future(0.13%),and continuous improvement(45.36%).In more than 50.00%of the regions that have been degraded in the past but were expected to improve in the future,the NDVI was expected to exhibit a stable trend of anti-persistent improvement.These findings provide theoretical support for future ecological protection,planning,and the implementation of ecological engineering in the MUSL,and also offer a theoretical basis for the planning and execution of construction projects,environmental protection measures,and the sustainable development of vegetation.
基金supported by the National Natural Science Foundation of China(No.92252201)。
文摘To address the early separation problem in the Menter Shear-Stress Transport(SST)turbulence model,a correction for the Turbulent Kinetic Energy(TKE)production term,P_(k),is introduced to account for the effect of the Adverse Pressure Gradient(APG).The correction is determined based on the distribution of Pkin the APG region before separation.When the friction coefficient C_(f) is decomposed,its direct dependence on Pkis clearly observed.However,with the introduction of Bradshaw’s assumption,Pkin the SST turbulence model is over-suppressed,resulting in a lower inner peak or no significant inner peak distribution at all.To address this problem,this paper proposes a Gaussian function,HGauss,which corrects the numerical values of P_(k) involved in the calculation of the Menter SST model by focusing on the inner peak region of P_(k).The modified SST model is then applied to four cases with APGs.The modification leads to an increase in the wall friction coefficient C_(f)in the APG region and causes a downstream shift in the separation location,improving the model’s consistency with high-accuracy data and experimental results.It is demonstrated that this correction can improve the early separation problem in the Menter SST turbulence model.
基金supported by the Key Project of the NationalLanguage Commission(No.ZDI145-110)the AcademicResearch Projects of Beijing Union University(No.ZK20202514)+1 种基金the Key Laboratory Project(No.YYZN-2024-6)the Project for the Construction and Support of High-Level Innovative Teams in Beijing Municipal Institutions(No.BPHR20220121).
文摘Gaze estimation,a crucial non-verbal communication cue,has achieved remarkable progress through convolutional neural networks.However,accurate gaze prediction in uncon-strained environments,particularly in extreme head poses,partial occlusions,and abnormal lighting,remains challenging.Existing models often struggle to effectively focus on discriminative ocular features,leading to suboptimal performance.To address these limitations,this paper proposes dual-branch gaze estimation with Gaussian mixture distribution heatmaps and dynamic adaptive loss function(DMGDL),a novel dual-branch gaze estimation algorithm.By introducing Gaussian mixture distribution heatmaps centered on pupil positions as spatial attention guides,the model is enabled to prioritize ocular regions.Additionally,a dual-branch network architecture is designed to separately extract features for yaw and pitch angles,enhancing flexibility and mitigating cross-angle interference.A dynamic adaptive loss function is further formulated to address discontinuities in angle estimation,improving robustness and convergence stability.Experimental evaluations on three benchmark datasets demonstrate that DMGDL outperforms state-of-the-art methods,achiev-ing a mean angular error of 3.98°on the Max-Planck institute for informatics face gaze(MPI-IFaceGaze)dataset,10.21°on the physically unconstrained gaze estimation in the wild(Gaze360)dataset and 6.14°on the real-time eye gaze estimation in natural environments(RT-Gene)dataset,exhibiting superior generalization and robustness.
基金supported by the National Natural Science Foundation of China(No.92252201)the Fundamental Research Funds for the Central Universitiesthe Academic Excellence Foundation of Beihang University(BUAA)for PhD Students。
文摘Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of unsteady flows.To enhance computational efficiency,we propose the Implicit-Explicit Two-Step Runge-Kutta(IMEX-TSRK)time-stepping discretization methods for unsteady flows,and develop a novel adaptive algorithm that correctly partitions spatial regions to apply implicit or explicit methods.The novel adaptive IMEX-TSRK schemes effectively handle the numerical stiffness of the small grid size and improve computational efficiency.Compared to implicit and explicit Runge-Kutta(RK)schemes,the IMEX-TSRK methods achieve the same order of accuracy with fewer first derivative calculations.Numerical case tests demonstrate that the IMEX-TSRK methods maintain numerical stability while enhancing computational efficiency.Specifically,in high Reynolds number flows,the computational efficiency of the IMEX-TSRK methods surpasses that of explicit RK schemes by more than one order of magnitude,and that of implicit RK schemes several times over.
文摘Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.
基金financially supported by the National Natural Science Foundation of China(52002157).
文摘Although organic compounds are considered to be promising electrode materials with their remarkable characteristics such as diverse structures,design controllability,and environmental friendliness,their low charge-transfer capability and limited cycling durability hinder their application in aqueous proton batteries.Herein,we prepared a noncovalent phenazine-based graphene aerogel(H/G)composite for aqueous proton storage,which is realized by redox-active Hexaazatrinaphthalene(HATN)organic compound combined with conductive reduced graphene oxide(rGO).The integration of rGO into HATN not only effectively optimizes the electronic structure of the H/G composite to enhance its electrochemical activity,but also the favorable noncovalent π-π interaction existed between HATN and rGO provides a stable structure for fast electron transportation.The obvious electron transfer in the aerogel composite promotes fast and reversible redox reactions occurred with the imino-active HATN in the composite electrode for proton uptake/removal in an aqueous acidic electrolyte,which are demonstrated by in-situ Fourier transform infrared(FTIR)investigation,theoretical calculations and experimental measurements.Therefore,it can deliver a fast,stable and efficient aqueous proton storage behavior with a large specific capacity of 274 mA·h·g^(-1) and considerable calendar life with~100%capacity retention after 3000 cycles,surpassing previously reported proton-based organic electrodes in aqueous acidic electrolytes.Furthermore,an outstanding soft-package aqueous proton(APB)has been fabricated with considerable long-term cycling stability.
基金supported by the National Natural Science Foundation of China(Nos.12005289,52072397)State Key Laboratory of Nuclear Detection and Electronics,University of Science and Technology of China(SKLPDE-KF-202316).
文摘The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.
基金supported by Shanghai Jiao Tong University(YG2022ZD005,YG2024QNA06).
文摘Accurate identification and viability assessment of the parathyroid glands(PGs)are critical when performing thyroid and parathyroid surgeries.Traditional visual inspection-based intrao-perative methods suffer from subjectivity and uncertainty.Near-infrared(NIR)imaging meth-ods,including NIR autofluorescence(NIRAF)imaging and indocyanine green fluorescence imaging(ICGFI),have emerged as promising and reliable techniques for intraoperative PG identification and assessment.Here,the principles and clinical performanoe of NIR imaging methods were comprehensively reviewed.
基金supported by the National Natural Science Foundation of China(Grant Nos.92252201 and 11721202)the Fundamental Research Funds for the Central Universities.
文摘We present the approaches to implementing the k-√k L turbulence model within the framework of the high-order discontinuous Galerkin(DG)method.We use the DG discretization to solve the full Reynolds-averaged Navier-Stokes equations.In order to enhance the robustness of approaches,some effective techniques are designed.The HWENO(Hermite weighted essentially non-oscillatory)limiting strategy is adopted for stabilizing the turbulence model variable k.Modifications have been made to the model equation itself by using the auxiliary variable that is always positive.The 2nd-order derivatives of velocities required in computing the von Karman length scale are evaluated in a way to maintain the compactness of DG methods.Numerical results demonstrate that the approaches have achieved the desirable accuracy for both steady and unsteady turbulent simulations.
