The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its...The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its fractional chromatic number. This paper gives an improvement of a theorem. And we show that several classes of circulant graphs are star extremal.展开更多
Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the ne...Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the necessary and sufficient condition on, such that f is uniquely extremal among the class. Further, for a general holomorphic function, the anthors suggest the models of the best possible growth conditions on, such that f is extremal or uniquely extremal among the class respectively.展开更多
It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and the...It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and there exists a sequence {tn}, 0<tn<1, /lim, tn =1, such that {(tnz)} is a Hamilton sequence. It is the precision of a theorem of Reich-Strebel in 1974, and gives a fairly satisfactory answer to a question of Reich in 1988.展开更多
Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of...Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of moduli problems on 5.展开更多
A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremal...A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremality relations in a topologically higher-dimensional black hole.A rescaled cosmological constant is added to the action of the massive gravity as a perturbative correction.This correction modifies the extremality bound of the black hole and leads to shifts in the mass,entropy,etc.Regarding the cosmological constant as a variable related to pressure,we obtain the thermodynamic extremality relations between the mass and entropy,pressure,charge,and parameters ci by accurate calculations.Finally,these relations are verified by a triple product identity,which shows that the universal relation exists in black holes.展开更多
Extreme traffic loads significantly challenge the safety and cost-effectiveness of highway bridges,especially under site-specific traffic conditions.Conventional assessments often rely on overly conservative load mode...Extreme traffic loads significantly challenge the safety and cost-effectiveness of highway bridges,especially under site-specific traffic conditions.Conventional assessments often rely on overly conservative load models,leading to excessive structural design.In this study,a framework for the prediction of maximum bending moments in simply supported bridges is developed by integrating weigh-in-motion(WIM)data,traffic microsimulation,and generalized extreme value(GEV)regression modeling to establish relationships between the GEV parameters(μ,σ,ξ)and traffic factors—heavy vehicle proportion,bridge span length,vehicle speed,headway,and traffic volume.Using one-year WIM data from 7.4 million vehicles,the developed models for μ and σ exhibit high predictive accuracy(R^(2)>0.95)and are validated through leave-one-out cross-validation.The prediction of ξ is less accurate(R^(2)≈0.6),requiring further improvement.Applying these models to a 1000-year return level yields a reliable,data-driven extrapolation,supporting optimized bridge design and safety assessment under varying traffic conditions.展开更多
The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in therm...The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in thermal photonic metamaterials(TPMs).This work introduces a novel multi-obj ective design framework and demonstrates the design,fabrication,and validation of a TPM operating under extreme temperatures up to 1873 K.We have established a holistic design framework integrating temperaturedependent neural network and Pareto multi-obj ective optimization to co-optimize spectral response,component light-weighting,and structural efficiency.The framework achieves 100 times faster computation than genetic algorithms.The performance of the designed TPM was evaluated under various atmospheric models and detection distances.The TPM achieved a peak radiance suppression efficiency of 82%and a maximum attenuation of-7.4 dB at 1200-1500 K.Experimentally,we fabricated an all-dielectric TPM using a refractory TiO_(2)/BeO multilayer stack with only 5 layers and 2um total thickness.The optimized structure shows high reflectivity(0.62 at 3-5 um;0.48 at 8-14μm)for radiative suppression and high emissivity(0.87 at 5-8μm)for radiative cooling.The TPM withstands 1873 K for 12 h in air with less than 3%spectral drift,retaining excellent mechanical properties.On high-temperature components,it achieves 40-50%radiative suppression and 40-60 K(~10.1 kW m^(-2))radiative cooling at 1100 K,endures over 20 times thermal shock cycles(>150 K s^(-1),700-1500 K),and maintains stable performance over 5 cycles,with 78%visible and 98%microwave transmittance.This work establishes a new paradigm in the design and application of photonic materials for extreme environments.展开更多
Focusing on civil aircraft flap skew detection design,this paper proposes a high-robustness monitoring design methodology to address insufficient monitor robustness that may trigger false alarms and disrupt airline op...Focusing on civil aircraft flap skew detection design,this paper proposes a high-robustness monitoring design methodology to address insufficient monitor robustness that may trigger false alarms and disrupt airline operations.Based on flap skew detection principles and threshold design criteria,the threshold range is defined with upper limit of maximum deformation under aerodynamic load and lower limit of sensor error margin and nominal flight deformation.Since the complex loading conditions of maximum flap differential deformation(max Δλ)during normal flight cannot be theoretically determined,probabilistic methods are employed:Flight test data from hundreds of sorties are analyzed using generalized extreme value distribution.Confidence levels are verified via Kolmogorov-Smirnov(K-S)hypothesis testing.Then probability density function of max Δλis established.The false alarm rate is calculated through cumulative probability values of max Δλat varying thresholds.Boundary conditions for false alarm rate are determined by safety assessment and dispatch reliability analysis.The derived monitoring threshold is verified against finite element analysis predictions and iron bird rig test.The results confirm the methodology’s validity,meeting all design objectives.展开更多
In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields...In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.展开更多
Hydrological extremes,such as floods,droughts,and compound events,are extremely dangerous to human societies,ecosystems,and infrastructures,whose frequency and severity are affected by climate change more and more.Eff...Hydrological extremes,such as floods,droughts,and compound events,are extremely dangerous to human societies,ecosystems,and infrastructures,whose frequency and severity are affected by climate change more and more.Effective disaster preparedness,water resource management,and climate adaptation have to do with accurate prediction and extensive risk assessment.This review sums up recent progress in predictive modeling and risk assessment systems in the framework of hydrological extremes in the changing climatic conditions.Statistical and empirical techniques,including extreme value theory and nonstationary frequency analysis,give probabilistic information using historic records,whereas process-based models give an understanding of physical hydrological processes at different climate and land-use conditions.New information-based and hybrid methods that use machine learning and high-resolution data take advantage of the complexity and nonlinearities and enhance the predictive power.Hazard,exposure,vulnerability,and adaptive capacity risk assessment models allow predictive output to be translated into actionable decision support,with socio-economic aspects and analysis of the scenario.Case studies of various regions across the globe show the use of these techniques to address floods,droughts,and compound events,with success and current problems.The review also addresses current trends such as compound hazard,multi-hazard integration,AI-enabled modelling,and cross-sectoral decision support,and outlines research priorities of improving predictive capability and resilience.This review will inform researchers,policymakers,and practitioners by offering a synthesis of all the effects of the hydrological extremes in climate change to formulate sound strategies for alleviating these effects.展开更多
This study investigated the characteristics and mechanisms of summer regional persistent extreme precipitation events(RPEPEs)over South China(SC)modulated by distinct intensity regimes of 10-30-day intraseasonal oscil...This study investigated the characteristics and mechanisms of summer regional persistent extreme precipitation events(RPEPEs)over South China(SC)modulated by distinct intensity regimes of 10-30-day intraseasonal oscillation(ISO).Diagnostic analyses revealed that the spatiotemporal evolution of RPEPEs exhibits robust phase-locking with the 10-30-day intraseasonal precipitation.By classifying RPEPEs into strong-ISO(SRPEPE)and weak-ISO(WRPEPE)composites based on the amplitude of 10-30-day filtered precipitation,we demonstrate a 14.6%enhancement in peak precipitation intensity during SRPEPEs compared to WRPEPEs.These distinct precipitation regimes are governed by fundamentally different Rossby wave teleconnection patterns over Eurasia.During SRPEPEs,a robust southeastward-propagating 10-30-day Rossby wave train originating from the Barents Sea traverses midlatitude Eurasia,effectively perturbing the northwestern Pacific upper-level circulation and establishing a favorable dynamic environment over SC.In contrast,WRPEPEs are associated with weaker eastward-propagating wave trains constrained along the subtropical jet stream.The horizontal convergence of background moisture driven by 10-30-day winds significantly amplifies lower-tropospheric humidity during SRPEPEs.The thermal advection of background temperature by 10-30-day geostrophic winds enhances baroclinic instability and vertical motion,intensifying precipitation under these moisture conditions.展开更多
Extreme rainfall events(EREs)frequently hit the middle and lower reaches of the Yellow River basin(YRB)during boreal summer.Recent observations have indicated that EREs exhibit teleconnection patterns across long spat...Extreme rainfall events(EREs)frequently hit the middle and lower reaches of the Yellow River basin(YRB)during boreal summer.Recent observations have indicated that EREs exhibit teleconnection patterns across long spatial distances.This study investigated ERE teleconnections in the YRB using the Event Synchronization(ES)method in combination with Complex Network(CN)theory.EREs in the YRB are significantly synchronized with other regions from regional to global scales.Additionally,high-resolution CMIP6 models in general show better skill in capturing these characteristics compared to low-resolution models.A further examination shows that the spatial synchronization patterns exhibit pronounced timescale dependence.Significant ERE synchronizations between the YRB and Europe were uncovered,where the YRB lags Eastern Europe by 3-5 days and Western Europe by 5-7 days,with Rossby wave propagation playing a key role.Wave trains from Europe propagate downstream along the Eurasian jet,inducing anomalous circulations over the YRB that enhance vertical upward motion and moisture transport,ultimately triggering EREs.Two distinct wave trains are observed:one is associated with Eastern Europe-YRB synchronization,occurring in the midlatitude region;the other is linked to Western Europe-YRB synchronization,positioned at higher latitudes.Notably,17.5%of Eastern Europe-YRB synchronization cases and 17.0%of Western Europe-YRB cases overlap.Quantitative analysis indicates that the synchronized events between Eastern(Western)Europe and the YRB account for roughly 28%(30%)of EREs in the YRB.These findings are critical for better understanding ERE mechanisms,offering guidance for forecasting and early warning capabilities for EREs in the YRB.展开更多
Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with ...Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with long bone fractures in the extremities admitted to Santai Hospital Affiliated to North Sichuan Medical College from January 2023 to January 2025 were included,including cases of upper extremity forearm fractures and lower extremity femoral and tibial fractures.The patients were evenly divided using a random number table,with the control group undergoing open reduction and internal fixation(ORIF)combined with autologous periosteum graft,and the observation group undergoing ORIF,autologous periosteum graft,and PRP injection.Surgical indicators,complication rates,excellent fracture healing rates,functional satisfaction,and joint range of motion were compared between the two groups.Results:The surgical indicators in the observation group were similar to those in the control group(p>0.05).The complication rate in the observation group was lower than that in the control group,while the excellent fracture healing rate and functional satisfaction were higher in the observation group(p<0.05).Conclusion:Autologous periosteum graft combined with PRP technology is safe and reliable for the treatment of long bone fractures in the extremities,with satisfactory clinical outcomes.展开更多
Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nai...Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nail bed related changes encountered in UET recipients in the literature.The differential diagnosis of nail abnormalities in UET includes a wide range of systemic,local and iatrogenic conditions other than immune responses to the allograft.It requires interdisciplinary evaluation by primary transplant surgeons,pathologists,dermatologists and immunologists.The possible underlying mechanisms of nail pathology in UET and the management are discussed.It also underscores the importance of onychodystrophy and need for timely intervention and to improve outcomes in UET recipients.展开更多
Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to h...Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to heat stress(PEHS)under different Shared Socioeconomic Pathways(SSPs)and Representative Concentration Pathways(RCPs)scenarios using a novel decomposition framework that separates the contributions of climate change,population change,and their interaction.Results show that global PEHS will increase substantially during the 21st century,with low-latitude regions experiencing the largest absolute increases,and high-latitude regions facing the largest relative increases.Globally,projected increases in PEHS under SSP3-7.0 are roughly three times those under SSP1-2.6,with low latitudes contributing about 70%-75%of the global total.SSP1-2.6 most effectively limits future heat exposure,with the highest risks in low-latitude developing regions,underscoring the need for low-emission pathways and targeted population and urbanization management.The findings highlight the urgent need for both climate mitigation and population adaptation strategies to address the growing and uneven heat exposure risks worldwide.展开更多
The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risk...The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risks,including floods and droughts.Recent research associated with the implementation of the Global Monsoons Model Intercomparison Project under the umbrella of CMIP6 has advanced our understanding of its historical variability and driving mechanisms.Observational data reveal a 20th-century shift:increased rainfall pre-1950s,followed by aridification and partial recovery post-1980s,driven by both internal variability(e.g.,Atlantic Multidecadal Oscillation)and external forcings(greenhouse gases,aerosols),while ENSO drives interannual variability through ocean-atmosphere interactions.Future projections under greenhouse forcing suggest long-term monsoon intensification,though regional disparities and model uncertainties persist.Models indicate robust trends but struggle to quantify extremes,where thermodynamic effects(warming-induced moisture rise)uniformly boost heavy rainfall,while dynamical shifts(circulation changes)create spatial heterogeneity.Volcanic eruptions and proposed solar radiation modification(SRM)further complicate predictions:tropical eruptions suppress monsoons,whereas high-latitude events alter cross-equatorial flows,highlighting unresolved feedbacks.The emergent constraint approach is booming in terms of correcting future projections and reducing uncertainty with respect to the global monsoons.Critical challenges remain.Model biases and sparse 20th-century observational data hinder accurate attribution.The interplay between natural variability and anthropogenic forcings,along with nonlinear extreme precipitation risks under warming,demands deeper mechanistic insights.Additionally,SRM’s regional impacts and hemispheric monsoon interactions require systematic evaluation.Addressing these gaps necessitates enhanced observational networks,refined climate models,and interdisciplinary efforts to disentangle multiscale drivers,ultimately improving resilience strategies for monsoon-dependent regions.展开更多
Recent studies have suggested that rapid warming over the Mongolian Plateau(MP)may intensify extreme heat events(EHEs).However,the characteristics and mechanisms driving summer EHEs over the MP(MP-EHEs)remain unclear....Recent studies have suggested that rapid warming over the Mongolian Plateau(MP)may intensify extreme heat events(EHEs).However,the characteristics and mechanisms driving summer EHEs over the MP(MP-EHEs)remain unclear.This study explores the interannual variations in summer MP-EHEs and their relationship with the summer soil moisture over the Inner Tibetan Plateau(TP-SM).The results reveal that changes in the MP-EHEs are linked to descending atmospheric motion induced by a local high-pressure system over the MP region.Descending motion further results in decreased mid-tolow-level cloud cover and increased shortwave radiation,thereby warming the surface and triggering summer MP-EHEs.Further analysis indicates that increased TP-SM results in a greater latent heat flux,triggering a local secondary circulation that reinforces the local high-pressure system over the MP region,thus serving to promote the occurrence of summer MPEHEs.Additionally,model results from the linear baroclinic model(LBM)and CMIP6 further confirm that variations in summer TP-SM contribute to the occurrence of the MP-EHEs.展开更多
This study takes"ocean heat waves"as a typical case to study the scientific definition,driving mechanisms,multi-dimensional impacts,and response strategies of extreme climate events.The definition of extreme...This study takes"ocean heat waves"as a typical case to study the scientific definition,driving mechanisms,multi-dimensional impacts,and response strategies of extreme climate events.The definition of extreme events requires a comprehensive consideration of statistical thresholds and social impacts.It is mainly driven by global warming caused by human emissions of greenhouse gases,and is also influenced by the interaction of natural variations such as ENSO.Extreme events cause systematic and cascading impacts on human health,infrastructure,agricultural economy,and ecosystems(especially marine ecosystems).Advanced technologies such as satellite remote sensing,climate models,and artificial intelligence have significantly enhanced their monitoring and prediction capabilities.However,effective responses still require a parallel strategy of mitigation and adaptation,and international cooperation is strengthened through the framework of the Paris Agreement.展开更多
Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive c...Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive classification of beach states around Hainan Island is conducted for the first time by utilizing theΩ-RTR model and geological control modes.Six distinct classic beach states ranging from dissipative to reflective are identified:barred dissipative beaches or no-barred dissipative beaches(BD or NBD),barred beaches(B),low-tide terrace or low-tide bar with rip(LTTR or LTBR),and reflective state(R).Among these,the BD and B types are predominant on Hainan Island.Notably,the beach states are subject to multiple factors,such as hydrodynamic forcings,geomorphic features and underlying substrates,and exhibit remarkable spatiotemporal variability.During extreme events,hydrodynamic forcings impact beach states more substantially than geological and geomorphic features do,leading to a more homogeneous distribution of beach states.Under normal circumstance,beach states are predominantly controlled by geological and geomorphic features.Coastal geological and geomorphic features have a pronounced influence on beach morphology and stability.For example,hard substrates underpin wide and stable dissipative beaches,whereas softer substrates lead to narrower,erosion-prone beaches.Three geological control modes are identified,namely,gently sloping hard substrates with dissipative beaches,moderately sloping hard substrates with seasonally variable reflective beaches,and steeply sloping soft substrates with dynamic sandbar-dominated beaches.These findings highlight the necessity of integrating geological settings in tandem with hydrodynamic forcings into coastal management practices.A dual-mode strategy is proposed:maintaining geomorphic self-organization on hard-substrate coasts under normal conditions and implementing hybrid engineering–ecological measures(e.g.,artificial sand replenishment and vegetation restoration)on erosion-prone soft substrates.展开更多
1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over ...1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over the past two decades,floods have inundated approximately 2.23 million km2 of land worldwide(Tellman et al.,2021),affecting over 250 million people and causing economic losses exceeding USD 651 billion(Devitt et al.,2023).Recent catastrophic floods in Pakistan,landslides in Indonesia,and dike breaches in China have intensified concerns over the effectiveness of current flood management strategies.展开更多
文摘The circular chromatic number and the fractional chromatic number are two generalizations of the ordinary chromatic number of a graph. We say a graph G is star extremal if its circular chromatic number is equal to its fractional chromatic number. This paper gives an improvement of a theorem. And we show that several classes of circulant graphs are star extremal.
文摘Consider the Teichmuller mapping f associated with in the unit disc D and the class of all quasiconformal mappings in D with the boundary values of f. For a special holomorphic function, the present paper gives the necessary and sufficient condition on, such that f is uniquely extremal among the class. Further, for a general holomorphic function, the anthors suggest the models of the best possible growth conditions on, such that f is extremal or uniquely extremal among the class respectively.
基金the National Natural Science Foundation of China!(No.19531060), the DoctoralProgram Fundation of the Ministry of Education o
文摘It is proved that if f is a Teichmuller self-mapping of the unit disk with a holomorphic quadratic deferential and satisfies the growth condition m(ψ，r)= o((1 -r)-), r→1, for any s>1, then f is extremal, and there exists a sequence {tn}, 0<tn<1, /lim, tn =1, such that {(tnz)} is a Hamilton sequence. It is the precision of a theorem of Reich-Strebel in 1974, and gives a fairly satisfactory answer to a question of Reich in 1988.
基金This work was partially supported by the National Natural Science Foundation of China (Grant No. 10501046).
文摘Given a compact Riemann surface S with finitely many punctures, in this paper we obtain a new extremality property of a Jenkins-Strebel differentialψon S. As a consequence, we obtain the solutions of several kinds of moduli problems on 5.
基金Supported by NSF C(11875196,11375121,11205125,11005016)Xihua University Talent Project(Z201021)。
文摘A universal relation between the leading correction to the entropy and extremality was proposed in the work of Goon and Penco.In this paper,we extend this work to massive gravity and investigate thermodynamic extremality relations in a topologically higher-dimensional black hole.A rescaled cosmological constant is added to the action of the massive gravity as a perturbative correction.This correction modifies the extremality bound of the black hole and leads to shifts in the mass,entropy,etc.Regarding the cosmological constant as a variable related to pressure,we obtain the thermodynamic extremality relations between the mass and entropy,pressure,charge,and parameters ci by accurate calculations.Finally,these relations are verified by a triple product identity,which shows that the universal relation exists in black holes.
基金The National Natural Science Foundation of China(No.52278149)the Natural Science Foundation of Jiangsu Province(No.BZ2024015)+1 种基金the Opening Project of State Key Laboratory for Track Technology of High-Speed Railway(No.2023YJ375)the Opening Project of Zhejiang Engineering Centre of Road and Bridge Intelligent Operation and Maintenance Technology(No.202402G).
文摘Extreme traffic loads significantly challenge the safety and cost-effectiveness of highway bridges,especially under site-specific traffic conditions.Conventional assessments often rely on overly conservative load models,leading to excessive structural design.In this study,a framework for the prediction of maximum bending moments in simply supported bridges is developed by integrating weigh-in-motion(WIM)data,traffic microsimulation,and generalized extreme value(GEV)regression modeling to establish relationships between the GEV parameters(μ,σ,ξ)and traffic factors—heavy vehicle proportion,bridge span length,vehicle speed,headway,and traffic volume.Using one-year WIM data from 7.4 million vehicles,the developed models for μ and σ exhibit high predictive accuracy(R^(2)>0.95)and are validated through leave-one-out cross-validation.The prediction of ξ is less accurate(R^(2)≈0.6),requiring further improvement.Applying these models to a 1000-year return level yields a reliable,data-driven extrapolation,supporting optimized bridge design and safety assessment under varying traffic conditions.
基金supported by National Key Research and Development Program of China(2024YFA1210500,2023YFB4606105)Fundamental Research Center Projects(52488301)of National Natural Science Foundation of China(NSFC)+1 种基金Key Research Program of Frontier Sciences(ZDBS-LYJSC030)of Chinese Academy of SciencesWestern Light Program(xbzg-zdsys-202402)of Chinese Academy of Sciences。
文摘The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in thermal photonic metamaterials(TPMs).This work introduces a novel multi-obj ective design framework and demonstrates the design,fabrication,and validation of a TPM operating under extreme temperatures up to 1873 K.We have established a holistic design framework integrating temperaturedependent neural network and Pareto multi-obj ective optimization to co-optimize spectral response,component light-weighting,and structural efficiency.The framework achieves 100 times faster computation than genetic algorithms.The performance of the designed TPM was evaluated under various atmospheric models and detection distances.The TPM achieved a peak radiance suppression efficiency of 82%and a maximum attenuation of-7.4 dB at 1200-1500 K.Experimentally,we fabricated an all-dielectric TPM using a refractory TiO_(2)/BeO multilayer stack with only 5 layers and 2um total thickness.The optimized structure shows high reflectivity(0.62 at 3-5 um;0.48 at 8-14μm)for radiative suppression and high emissivity(0.87 at 5-8μm)for radiative cooling.The TPM withstands 1873 K for 12 h in air with less than 3%spectral drift,retaining excellent mechanical properties.On high-temperature components,it achieves 40-50%radiative suppression and 40-60 K(~10.1 kW m^(-2))radiative cooling at 1100 K,endures over 20 times thermal shock cycles(>150 K s^(-1),700-1500 K),and maintains stable performance over 5 cycles,with 78%visible and 98%microwave transmittance.This work establishes a new paradigm in the design and application of photonic materials for extreme environments.
文摘Focusing on civil aircraft flap skew detection design,this paper proposes a high-robustness monitoring design methodology to address insufficient monitor robustness that may trigger false alarms and disrupt airline operations.Based on flap skew detection principles and threshold design criteria,the threshold range is defined with upper limit of maximum deformation under aerodynamic load and lower limit of sensor error margin and nominal flight deformation.Since the complex loading conditions of maximum flap differential deformation(max Δλ)during normal flight cannot be theoretically determined,probabilistic methods are employed:Flight test data from hundreds of sorties are analyzed using generalized extreme value distribution.Confidence levels are verified via Kolmogorov-Smirnov(K-S)hypothesis testing.Then probability density function of max Δλis established.The false alarm rate is calculated through cumulative probability values of max Δλat varying thresholds.Boundary conditions for false alarm rate are determined by safety assessment and dispatch reliability analysis.The derived monitoring threshold is verified against finite element analysis predictions and iron bird rig test.The results confirm the methodology’s validity,meeting all design objectives.
基金supported in part by the National Natural Science Foundation of China(Nos.12175100 and 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.21B0402,18A237,22A0305)the Natural Science Foundation of Hunan Province,China(No.2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China(No.ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(No.2019KFZ10)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20251453)。
文摘In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.
文摘Hydrological extremes,such as floods,droughts,and compound events,are extremely dangerous to human societies,ecosystems,and infrastructures,whose frequency and severity are affected by climate change more and more.Effective disaster preparedness,water resource management,and climate adaptation have to do with accurate prediction and extensive risk assessment.This review sums up recent progress in predictive modeling and risk assessment systems in the framework of hydrological extremes in the changing climatic conditions.Statistical and empirical techniques,including extreme value theory and nonstationary frequency analysis,give probabilistic information using historic records,whereas process-based models give an understanding of physical hydrological processes at different climate and land-use conditions.New information-based and hybrid methods that use machine learning and high-resolution data take advantage of the complexity and nonlinearities and enhance the predictive power.Hazard,exposure,vulnerability,and adaptive capacity risk assessment models allow predictive output to be translated into actionable decision support,with socio-economic aspects and analysis of the scenario.Case studies of various regions across the globe show the use of these techniques to address floods,droughts,and compound events,with success and current problems.The review also addresses current trends such as compound hazard,multi-hazard integration,AI-enabled modelling,and cross-sectoral decision support,and outlines research priorities of improving predictive capability and resilience.This review will inform researchers,policymakers,and practitioners by offering a synthesis of all the effects of the hydrological extremes in climate change to formulate sound strategies for alleviating these effects.
基金sponsored by the National Natural Science Foundation of China (grant 42575038)the National Key Research and Development Program of China (grant2022YFF0801702)the National Natural Science Foundation of China (grant 42206257 and 42205163)
文摘This study investigated the characteristics and mechanisms of summer regional persistent extreme precipitation events(RPEPEs)over South China(SC)modulated by distinct intensity regimes of 10-30-day intraseasonal oscillation(ISO).Diagnostic analyses revealed that the spatiotemporal evolution of RPEPEs exhibits robust phase-locking with the 10-30-day intraseasonal precipitation.By classifying RPEPEs into strong-ISO(SRPEPE)and weak-ISO(WRPEPE)composites based on the amplitude of 10-30-day filtered precipitation,we demonstrate a 14.6%enhancement in peak precipitation intensity during SRPEPEs compared to WRPEPEs.These distinct precipitation regimes are governed by fundamentally different Rossby wave teleconnection patterns over Eurasia.During SRPEPEs,a robust southeastward-propagating 10-30-day Rossby wave train originating from the Barents Sea traverses midlatitude Eurasia,effectively perturbing the northwestern Pacific upper-level circulation and establishing a favorable dynamic environment over SC.In contrast,WRPEPEs are associated with weaker eastward-propagating wave trains constrained along the subtropical jet stream.The horizontal convergence of background moisture driven by 10-30-day winds significantly amplifies lower-tropospheric humidity during SRPEPEs.The thermal advection of background temperature by 10-30-day geostrophic winds enhances baroclinic instability and vertical motion,intensifying precipitation under these moisture conditions.
基金the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2023B1515020084)the National Natural Science Foundation of China (Grant Nos.42175068, 42475057, and 42261144687)
文摘Extreme rainfall events(EREs)frequently hit the middle and lower reaches of the Yellow River basin(YRB)during boreal summer.Recent observations have indicated that EREs exhibit teleconnection patterns across long spatial distances.This study investigated ERE teleconnections in the YRB using the Event Synchronization(ES)method in combination with Complex Network(CN)theory.EREs in the YRB are significantly synchronized with other regions from regional to global scales.Additionally,high-resolution CMIP6 models in general show better skill in capturing these characteristics compared to low-resolution models.A further examination shows that the spatial synchronization patterns exhibit pronounced timescale dependence.Significant ERE synchronizations between the YRB and Europe were uncovered,where the YRB lags Eastern Europe by 3-5 days and Western Europe by 5-7 days,with Rossby wave propagation playing a key role.Wave trains from Europe propagate downstream along the Eurasian jet,inducing anomalous circulations over the YRB that enhance vertical upward motion and moisture transport,ultimately triggering EREs.Two distinct wave trains are observed:one is associated with Eastern Europe-YRB synchronization,occurring in the midlatitude region;the other is linked to Western Europe-YRB synchronization,positioned at higher latitudes.Notably,17.5%of Eastern Europe-YRB synchronization cases and 17.0%of Western Europe-YRB cases overlap.Quantitative analysis indicates that the synchronized events between Eastern(Western)Europe and the YRB account for roughly 28%(30%)of EREs in the YRB.These findings are critical for better understanding ERE mechanisms,offering guidance for forecasting and early warning capabilities for EREs in the YRB.
文摘Objective:To analyze the clinical application value of autologous periosteum graft combined with platelet-rich plasma(PRP)in the treatment of long bone fractures in the extremities.Methods:A total of 40 patients with long bone fractures in the extremities admitted to Santai Hospital Affiliated to North Sichuan Medical College from January 2023 to January 2025 were included,including cases of upper extremity forearm fractures and lower extremity femoral and tibial fractures.The patients were evenly divided using a random number table,with the control group undergoing open reduction and internal fixation(ORIF)combined with autologous periosteum graft,and the observation group undergoing ORIF,autologous periosteum graft,and PRP injection.Surgical indicators,complication rates,excellent fracture healing rates,functional satisfaction,and joint range of motion were compared between the two groups.Results:The surgical indicators in the observation group were similar to those in the control group(p>0.05).The complication rate in the observation group was lower than that in the control group,while the excellent fracture healing rate and functional satisfaction were higher in the observation group(p<0.05).Conclusion:Autologous periosteum graft combined with PRP technology is safe and reliable for the treatment of long bone fractures in the extremities,with satisfactory clinical outcomes.
文摘Nail changes following upper extremity transplantation(UET)cannot be overlooked as they possess diagnostic and prognostic relevance in allotransplantation of upper limbs.This comprehensive review explores nail and nail bed related changes encountered in UET recipients in the literature.The differential diagnosis of nail abnormalities in UET includes a wide range of systemic,local and iatrogenic conditions other than immune responses to the allograft.It requires interdisciplinary evaluation by primary transplant surgeons,pathologists,dermatologists and immunologists.The possible underlying mechanisms of nail pathology in UET and the management are discussed.It also underscores the importance of onychodystrophy and need for timely intervention and to improve outcomes in UET recipients.
基金funded by National Natural Science Foundation of China(Grant No.42271273)Swedish Research Council(VR:2021-02163).
文摘Global warming and socioeconomic development are expected to exacerbate human exposure to heat stress,but the extent and inequality of such changes remain unclear.Here,we quantified the future population exposure to heat stress(PEHS)under different Shared Socioeconomic Pathways(SSPs)and Representative Concentration Pathways(RCPs)scenarios using a novel decomposition framework that separates the contributions of climate change,population change,and their interaction.Results show that global PEHS will increase substantially during the 21st century,with low-latitude regions experiencing the largest absolute increases,and high-latitude regions facing the largest relative increases.Globally,projected increases in PEHS under SSP3-7.0 are roughly three times those under SSP1-2.6,with low latitudes contributing about 70%-75%of the global total.SSP1-2.6 most effectively limits future heat exposure,with the highest risks in low-latitude developing regions,underscoring the need for low-emission pathways and targeted population and urbanization management.The findings highlight the urgent need for both climate mitigation and population adaptation strategies to address the growing and uneven heat exposure risks worldwide.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0608904)the International Partnership Program of the Chinese Academy of Sciences(Grant Nos.060GJHZ2023079GC and 134111KYSB20160031)+1 种基金supported by the Office of Science,U.S.Department of Energy(DOE)Biological and Environmental Research as part of the Regional and Global Model Analysis program area through the Water Cycle and Climate Extremes Modeling(WACCEM)scientific focus areaoperated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830。
文摘The global monsoon system,encompassing the Asian-Australian,African,and American monsoons,sustains two-thirds of the world’s population by regulating water resources and agriculture.Monsoon anomalies pose severe risks,including floods and droughts.Recent research associated with the implementation of the Global Monsoons Model Intercomparison Project under the umbrella of CMIP6 has advanced our understanding of its historical variability and driving mechanisms.Observational data reveal a 20th-century shift:increased rainfall pre-1950s,followed by aridification and partial recovery post-1980s,driven by both internal variability(e.g.,Atlantic Multidecadal Oscillation)and external forcings(greenhouse gases,aerosols),while ENSO drives interannual variability through ocean-atmosphere interactions.Future projections under greenhouse forcing suggest long-term monsoon intensification,though regional disparities and model uncertainties persist.Models indicate robust trends but struggle to quantify extremes,where thermodynamic effects(warming-induced moisture rise)uniformly boost heavy rainfall,while dynamical shifts(circulation changes)create spatial heterogeneity.Volcanic eruptions and proposed solar radiation modification(SRM)further complicate predictions:tropical eruptions suppress monsoons,whereas high-latitude events alter cross-equatorial flows,highlighting unresolved feedbacks.The emergent constraint approach is booming in terms of correcting future projections and reducing uncertainty with respect to the global monsoons.Critical challenges remain.Model biases and sparse 20th-century observational data hinder accurate attribution.The interplay between natural variability and anthropogenic forcings,along with nonlinear extreme precipitation risks under warming,demands deeper mechanistic insights.Additionally,SRM’s regional impacts and hemispheric monsoon interactions require systematic evaluation.Addressing these gaps necessitates enhanced observational networks,refined climate models,and interdisciplinary efforts to disentangle multiscale drivers,ultimately improving resilience strategies for monsoon-dependent regions.
基金supported by the National Natural Science Foundation of China(Grant No.42288101)the Young Scientists Fund of the National Natural Science Foundation of China(Grand No.42505018)the Shanghai“Science and Technology Innovation Action Plan”Venus Project(Grant No.23YF1437300)。
文摘Recent studies have suggested that rapid warming over the Mongolian Plateau(MP)may intensify extreme heat events(EHEs).However,the characteristics and mechanisms driving summer EHEs over the MP(MP-EHEs)remain unclear.This study explores the interannual variations in summer MP-EHEs and their relationship with the summer soil moisture over the Inner Tibetan Plateau(TP-SM).The results reveal that changes in the MP-EHEs are linked to descending atmospheric motion induced by a local high-pressure system over the MP region.Descending motion further results in decreased mid-tolow-level cloud cover and increased shortwave radiation,thereby warming the surface and triggering summer MP-EHEs.Further analysis indicates that increased TP-SM results in a greater latent heat flux,triggering a local secondary circulation that reinforces the local high-pressure system over the MP region,thus serving to promote the occurrence of summer MPEHEs.Additionally,model results from the linear baroclinic model(LBM)and CMIP6 further confirm that variations in summer TP-SM contribute to the occurrence of the MP-EHEs.
基金Supported by the School-level Project of Sichuan Minzu College(XYZB2017ZB).
文摘This study takes"ocean heat waves"as a typical case to study the scientific definition,driving mechanisms,multi-dimensional impacts,and response strategies of extreme climate events.The definition of extreme events requires a comprehensive consideration of statistical thresholds and social impacts.It is mainly driven by global warming caused by human emissions of greenhouse gases,and is also influenced by the interaction of natural variations such as ENSO.Extreme events cause systematic and cascading impacts on human health,infrastructure,agricultural economy,and ecosystems(especially marine ecosystems).Advanced technologies such as satellite remote sensing,climate models,and artificial intelligence have significantly enhanced their monitoring and prediction capabilities.However,effective responses still require a parallel strategy of mitigation and adaptation,and international cooperation is strengthened through the framework of the Paris Agreement.
基金The Science and Technology Basic Investigation Program of China,No.2022FY202404。
文摘Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive classification of beach states around Hainan Island is conducted for the first time by utilizing theΩ-RTR model and geological control modes.Six distinct classic beach states ranging from dissipative to reflective are identified:barred dissipative beaches or no-barred dissipative beaches(BD or NBD),barred beaches(B),low-tide terrace or low-tide bar with rip(LTTR or LTBR),and reflective state(R).Among these,the BD and B types are predominant on Hainan Island.Notably,the beach states are subject to multiple factors,such as hydrodynamic forcings,geomorphic features and underlying substrates,and exhibit remarkable spatiotemporal variability.During extreme events,hydrodynamic forcings impact beach states more substantially than geological and geomorphic features do,leading to a more homogeneous distribution of beach states.Under normal circumstance,beach states are predominantly controlled by geological and geomorphic features.Coastal geological and geomorphic features have a pronounced influence on beach morphology and stability.For example,hard substrates underpin wide and stable dissipative beaches,whereas softer substrates lead to narrower,erosion-prone beaches.Three geological control modes are identified,namely,gently sloping hard substrates with dissipative beaches,moderately sloping hard substrates with seasonally variable reflective beaches,and steeply sloping soft substrates with dynamic sandbar-dominated beaches.These findings highlight the necessity of integrating geological settings in tandem with hydrodynamic forcings into coastal management practices.A dual-mode strategy is proposed:maintaining geomorphic self-organization on hard-substrate coasts under normal conditions and implementing hybrid engineering–ecological measures(e.g.,artificial sand replenishment and vegetation restoration)on erosion-prone soft substrates.
基金supported by National Key Research and Development Program of China(Grants No.2022YFF0802401 and 2023YFF0806900)China Postdoctoral Science Foundation(Grants No.2023M743456,GZB20230740,and 2024T170908).
文摘1.Introduction In recent years,intensifying climate extremes have triggered a sharp increase in global natural disasters,over 90%attributable to water-related hazards,particularly floods(Hirabayashi et al.,2013).Over the past two decades,floods have inundated approximately 2.23 million km2 of land worldwide(Tellman et al.,2021),affecting over 250 million people and causing economic losses exceeding USD 651 billion(Devitt et al.,2023).Recent catastrophic floods in Pakistan,landslides in Indonesia,and dike breaches in China have intensified concerns over the effectiveness of current flood management strategies.
