Amid global warming,mountainous regions have emerged as critical zones of investigation owing to their heightened vulnerability to climate change,their ecological significance,and the intensified interactions between ...Amid global warming,mountainous regions have emerged as critical zones of investigation owing to their heightened vulnerability to climate change,their ecological significance,and the intensified interactions between natural stress and human activities.Land surface temperature(LST)is a fundamental indicator for assessing climatic sensitivity in these landscapes.However,a comprehensive understanding of the spatiotemporal dynamics and driving mechanisms of LST across large mountainous regions remains limited.Therefore,data from the Terra Moderate Resolution Imaging Spectroradiometer Land Surface Temperature/Emissivity Daily(MOD11A1)Version 6.1 product during 2001–2020 in Yunnan Province(a complex mountainous region),China,were analyzed.Sen's slope analysis and Mann-Kendall test were applied to detect LST trends and spatial heterogeneity at both annual and seasonal scales.Subsequently,an eXtreme Gradient Boosting(XGBoost)model coupled with SHapley Additive exPlanations(SHAP)was employed to clarify the nonlinear contributions of multiple drivers.The study revealed the following findings.LST exhibited an overall warming rate of 0.020℃/a,characterized by daytime cooling(–0.008℃/a)and nighttime warming(0.048℃/a).LST increased during spring,summer,and autumn(0.011℃/a–0.018℃/a),whereas winter LST exhibited a cooling trend(–0.011℃/a).These variations were spatially partitioned by the Ailao Mountains,with the southwest displaying stronger thermal changes than the northeast.Natural controls,including digital elevation model(DEM)and downward shortwave radiation(DSR),predominated in the northwest high mountain canyons area and south tropical rainforest area,whereas nature–human interactions were more pronounced in the central urban agglomeration warming area and southeast karst landform area.The dominant drivers consisted of DEM,DSR,Normalized Difference Moisture Index,particulate matter 2.5(PM2.5),and aerosol optical depth(AOD).The strong correlations between gross domestic product and population density(correlation coefficient(r)=0.95),as well as between PM2.5 and AOD(r=0.84),highlighted the increasing influence of socioeconomic factors on surface warming.This study can advance the understanding of how mountain topography,moisture,and anthropogenic pressures jointly regulate surface thermal regimes and provide region-specific insights for climate adaptation and sustainable ecosystem management.展开更多
To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the accele...To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the acceleration signal of the bridge structure through data reconstruction.The extreme gradient boosting tree(XGBoost)was then used to perform analysis on the feature data to achieve damage detection with high accuracy and high performance.The proposed method was applied in a numerical simulation study on a three-span continuous girder and further validated experimentally on a scaled model of a cable-stayed bridge.The numerical simulation results show that the identification errors remain within 2.9%for six single-damage cases and within 3.1%for four double-damage cases.The experimental validation results demonstrate that when the tension in a single cable of the cable-stayed bridge decreases by 20%,the method accurately identifies damage at different cable locations using only sensors installed on the main girder,achieving identification accuracies above 95.8%in all cases.The proposed method shows high identification accuracy and generalization ability across various damage scenarios.展开更多
基金supported by the National Natural Science Foundation of China(42061004)the Youth Special Project of Xing Dian Talent Support Program of Yunnan Province,China(XDYC-QNRC-2022-0230)+1 种基金the Open Subjects of First-class Disciplines in Soil and Water Conservation and Desertification Control in Yunnan Province,China(SBK20240021)the Special Project for Building a Science and Technology Innovation Center for South and Southeast Asia,China(202503AP140004)。
摘要Amid global warming,mountainous regions have emerged as critical zones of investigation owing to their heightened vulnerability to climate change,their ecological significance,and the intensified interactions between natural stress and human activities.Land surface temperature(LST)is a fundamental indicator for assessing climatic sensitivity in these landscapes.However,a comprehensive understanding of the spatiotemporal dynamics and driving mechanisms of LST across large mountainous regions remains limited.Therefore,data from the Terra Moderate Resolution Imaging Spectroradiometer Land Surface Temperature/Emissivity Daily(MOD11A1)Version 6.1 product during 2001–2020 in Yunnan Province(a complex mountainous region),China,were analyzed.Sen's slope analysis and Mann-Kendall test were applied to detect LST trends and spatial heterogeneity at both annual and seasonal scales.Subsequently,an eXtreme Gradient Boosting(XGBoost)model coupled with SHapley Additive exPlanations(SHAP)was employed to clarify the nonlinear contributions of multiple drivers.The study revealed the following findings.LST exhibited an overall warming rate of 0.020℃/a,characterized by daytime cooling(–0.008℃/a)and nighttime warming(0.048℃/a).LST increased during spring,summer,and autumn(0.011℃/a–0.018℃/a),whereas winter LST exhibited a cooling trend(–0.011℃/a).These variations were spatially partitioned by the Ailao Mountains,with the southwest displaying stronger thermal changes than the northeast.Natural controls,including digital elevation model(DEM)and downward shortwave radiation(DSR),predominated in the northwest high mountain canyons area and south tropical rainforest area,whereas nature–human interactions were more pronounced in the central urban agglomeration warming area and southeast karst landform area.The dominant drivers consisted of DEM,DSR,Normalized Difference Moisture Index,particulate matter 2.5(PM2.5),and aerosol optical depth(AOD).The strong correlations between gross domestic product and population density(correlation coefficient(r)=0.95),as well as between PM2.5 and AOD(r=0.84),highlighted the increasing influence of socioeconomic factors on surface warming.This study can advance the understanding of how mountain topography,moisture,and anthropogenic pressures jointly regulate surface thermal regimes and provide region-specific insights for climate adaptation and sustainable ecosystem management.
基金The National Natural Science Foundation of China(No.52361165658,52378318,52078459).
摘要To enhance the accuracy and efficiency of bridge damage identification,a novel data-driven damage identification method was proposed.First,convolutional autoencoder(CAE)was used to extract key features from the acceleration signal of the bridge structure through data reconstruction.The extreme gradient boosting tree(XGBoost)was then used to perform analysis on the feature data to achieve damage detection with high accuracy and high performance.The proposed method was applied in a numerical simulation study on a three-span continuous girder and further validated experimentally on a scaled model of a cable-stayed bridge.The numerical simulation results show that the identification errors remain within 2.9%for six single-damage cases and within 3.1%for four double-damage cases.The experimental validation results demonstrate that when the tension in a single cable of the cable-stayed bridge decreases by 20%,the method accurately identifies damage at different cable locations using only sensors installed on the main girder,achieving identification accuracies above 95.8%in all cases.The proposed method shows high identification accuracy and generalization ability across various damage scenarios.