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Numerical Simulation Analysis of Welded Joints in Arch Ribs of Large Span Steel Pipe Arch Bridges

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Journal of Harbin Institute of technology(New Series) 2024年第3期31卷 19-30页

作者： Deer He Nianchun Deng Xiuning Peng School of Civil Engineering and Architecture Guangxi UniversityNanning 530004China Guangxi Key Laboratory of disaster Prevention and reduction and Engineering Safety Nanning 530004China

In order to study the residual stress distribution law of welded joints of arch ribs of large-span steel pipe concrete arch bridges,numerical simulation of temperature,stress and strain fields based on ABAQUS for welded joints of arch-ribbed steel tubes using 7-,8-and 9-layer welds is carried out and its accuracy is *** steel pipe welding temperature changes,residual stress distribution,different processes residual stress changes in the law,the prediction of post-weld residual stress distribution and deformation are studied in this *** results show that the temperature field values and test results are more consistent with the accuracy of numerical simulation of welding,the welding process is mainly in the form of heat transfer;Residual high stresses are predominantly distributed in the Fusion zone(FZ)and Heat-affected zone(HAZ),with residual stress levels tending to decrease from the center of the weld along the axial path,the maximum stress appears in the FZ and HAZ junction;The number of welding layers has an effect on the residual stress distribution,the number of welding layers increases,the residual stress tends to decrease,while the FZ and HAZ high stress area range shrinks;Increasing the number of plies will increase the amount of residual distortion.

关键词： steel pipe and concrete arch bridge arch rib multi-pass welding residual stress numerical simulation

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Understanding and improving Yangtze River Basin summer precipitation prediction using an optimal multi-Physics ensemble

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Frontiers of Earth science 2024年第1期18卷 256-277页

作者： Yang ZHAO Fengxue QIAO Xin-Zhong LIANG Jinhua YU Climate Environment and Sustainability CenterNanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Geographic Information science(Ministry of Education) East China Normal UniversityShanghai 200241China School of Geographic sciences East China Normal UniversityShanghai 200241China Department of Atmospheric and Oceanic science University of MarylandCollege Park MD 20740USA Earth System science Interdisciplinary center University of MarylandCollege Park MD 20740USA Key Laboratory of Meteorological disaster(KLME)(Ministry of Education)/Collaborative Innovation center on Forecast and Evaluation of Meteorological disasters(CIC-FEMD) Nanjing University of Information Science and TechnologyNanjing 210044China

This study employs the regional Climate-Weather Research and Forecasting model(CWRF)to first investigate the primary physical mechanisms causing biases in simulating summer precipitation over the Yangtze River Basin(YRB),and then enhance its predictive ability through an optimal multi-physics ensemble *** CWRF 30-km simulations in China are compared among 28 combinations of varying physics parameterizations during 1980−***-term average summer biases in YRB precipitation are remotely correlated with those of large-scale *** teleconnections of biases are highly consistent with the observed correlation patterns between interannual variations of precipitation and circulations,despite minor shifts in their primary action *** YRB precipitation aligns with a southward shifted East Asian westerly jet,an intensified low-level southerly flow south of YRB,and a south-eastward shifted South Asian high,alongside higher moisture availability over ***,decreased YRB precipitation corresponds to an opposite circulation *** CWRF control configuration using the ensemble cumulus parameterization(ECP),compared to other cumulus schemes,best captures the observed YRB precipitation characteristics and associated circulation *** ECP with the Morrison or Morrison-aerosol microphysics and the CCCMA or CAML radiation schemes enhances the overall CWRF *** to the control CWRF,the ensemble average of these skill-enhanced physics configurations more accurately reproduces YRB summer precipitation’s spatial distributions,interannual anomalies,and associated circulation *** Bayesian Joint Probability calibration to these configurations improves the ensemble’s spatial distributions but compromises its interannual anomalies and teleconnection *** findings highlight substantial potential for refining the representation of climate system physics to improve YRB precipitation *** is notabl

关键词： physics parameterization regional climate model downscaling skill enhancement multi-physics ensemble teleconnection bias reduction

Role of Stokes Drift in Ocean Dynamics Under Typhoon Conditions in the Bohai Sea

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Journal of Ocean University of China 2024年第1期23卷 33-45页

作者： LI Haoqian WAN Kai WANG Menghan DENG Zeng’an CAO Yu North China Sea Marine Forecasting center Qingdao 266061China Shandong Provincial Key Laboratory of Marine Ecology and Environment&disaster Prevention and Mitigation Qingdao 266061China North China Sea Offshore Engineering Survey Institute Qingdao 266061China School of Marine science and technology Tianjin UniversityTianjin 300072China South China Sea Marine Forecasting center Guangzhou 510006China

The effect of Stokes drift production(SDP),which includes Coriolis-Stokes forcing,Langmuir circulation,and Craik-Lei-bovich vortexes,on the upper ocean during typhoon passage in the Bohai Sea(BS),China,is investigated by using a coupled wave-current *** role of SDP in turbulent mixing and the further dynamics during the entire typhoon period are comprehensively *** results show that SDP greatly increases turbulent mixing at all depths under typhoon conditions by up to seven times that under normal weather *** generally strengthens sea surface cooling by more than 0.4℃,with the maximum reduction in sea surface temperature(SST)at the during-typhoon stage exceeding 2℃,which is approximately seven times larger than that under normal weather *** SDP-induced decrease in current speed can exceed 0.2ms^(-1),and the change in current direction is generally opposite the wind *** results suggest that Stokes drift depresses the effect of strong winds on currents by intensifying turbulent *** layer depth(MLD)is distinctly increased by O(1)during typhoons due to SDP and can deepen by more than *** addition,the continuous effects of SDP on SST,current,and MLD at the after-typhoon stage indi-cate a hysteretic response between SDP and typhoon actions.

关键词： Stokes drift production Langmuir turbulence rurbulent mixing typhoon coupled model

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High-rate electrochemical H_(2)O_(2) production over multimetallic atom catalysts under acidic–neutral conditions

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Carbon Energy 2024年第1期6卷 44-62页

作者： Yueyu Tong Jiaxin Liu Bing-Jian Su Jenh-Yih Juang Feng Hou Lichang Yin Shi Xue Dou Ji Liang Key Laboratory for Advanced Ceramics and Machining technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjinChina Institute for Superconducting and Electronic Materials University of WollongongInnovation CampusNorth WollongongNew South WalesAustralia Department of Electrophysics National Chiao Tung UniversityHsinchuTaiwanChina Shenyang National Laboratory for Materials science Institute of Metal ResearchChinese Academy of SciencesShenyangLiaoningChina Institute of Energy Materials science University of Shanghai for Science and TechnologyShanghaiChina

Hydrogen peroxide(H_(2)O_(2))production by the electrochemical 2-electron oxygen reduction reaction(2e−ORR)is a promising alternative to the energy-intensive anthraquinone process,and single-atom electrocatalysts show the unique capability of high selectivity toward 2e−ORR against the 4e−*** extremely low surface density of the single-atom sites and the inflexibility in manipulating their geometric/electronic configurations,however,compromise the H_(2)O_(2) yield and impede further performance ***,we construct a family of multiatom catalysts(MACs),on which two or three single atoms are closely coordinated to form high-density active sites that are versatile in their atomic configurations for optimal adsorption of essential*OOH *** them,the Cox–Ni MAC presents excellent electrocatalytic performance for 2e−ORR,in terms of its exceptionally high H_(2)O_(2) yield in acidic electrolytes(28.96 mol L^(−1) gcat.^(−1) h^(−1))and high selectivity under acidic to neutral conditions in a wide potential region(>80%,0–0.7 V).Operando X-ray absorption and density functional theory analyses jointly unveil its unique trimetallic Co2NiN8 configuration,which efficiently induces an appropriate Ni–d orbital filling and modulates the*OOH adsorption,together boosting the electrocatalytic 2e−ORR *** work thus provides a new MAC strategy for tuning the geometric/electronic structure of active sites for 2e−ORR and other potential electrochemical processes.

关键词： hydrogen peroxide production multiatom catalysts operando X-ray adsorption spectrum reaction mechanism tendency structure-property relation

COP 28: Challenge of coping with climate crisis

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The Innovation 2024年第1期5卷 21-22页

作者： Tong Jiang Xiaojia He Buda Su Peni Hausia Havea Ke Wei Zbigniew W.Kundzewicz Dong Liu Research Institute of Climatic and Environmental Governance/Institute for disaster Risk Management School of Geographical ScienceNanjing University of Information Science&TechnologyNanjing 210044China The Administrative center for China’s Agenda 21 Beijing 100038China Pacific Global Solution Nuku’alofaTongatapu 000676Tonga Centre for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Environmental Engineering and Mechanical Engineering Poznan University of Life Sciences60-637 PoznanPoland The Paper Shanghai United Media GroupShanghai 200040China

The 28th Conference of Parties(COP 28)of the United Nations Framework Convention on Climate Change(UNFCCC)is being held in Dubai,United Arab Emirates,from November 30 to December 12,2023,with the participation of over 160 world leaders(Figure 1).The tone of the COP 28 is set by the observation that,clearly,the nationally determined contributions related to CO_(2) emission reduction are not on track to curb the temperature rise as per the Paris *** order to hold the increase in global mean temperature to well below 2℃ above the pre-industrial level and to pursue efforts to limit the warming to 1.5℃,there is a need for ratcheting up ambition for near-term climate action.

关键词： Figure limit COP

Long-Term Extreme Wave Characteristics in the Water Adjacent to China Based on ERA5 Reanalysis Data

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Journal of Ocean University of China 2024年第1期23卷 1-10页

作者： DU Wenyan ZHANG Xuri SHI Hongyuan LI Guanyu ZHOU Zhengqiao YOU Zaijin ZHANG Kuncheng School of Hydraulic Engineering Ludong UniversityYantai 264025China center for Ports and Maritime Safety(CPMS) Dalian Maritime UniversityDalian 1160263China Nation Ocean technology center Tianjin 300111China Navigation Guarantee center of South China Sea(NGCS)MOT Guangzhou Hydrographic center Guangzhou 510320China Institute of Marine Development/Military Teaching Department School of MarxismOcean University of ChinaQingdao 266100China Yantai Kekan Marine technology Co. Ltd.Yantai 264025China

Extreme waves have a profound impact on coastal infrastructure;thus,understanding the variation law of risky analysis and disaster prevention in coastal zones is *** paper analyzed the spatiotemporal characteristics of extreme wave heights adjacent to China from 1979 to 2018 based on the ERA5 *** extreme value analysis is undertaken in eight repre-sentative points to investigate the trends in the values of 50-and 100-year wave *** show that the mean value of extreme waves is the largest in the eastern part of taiwan Island and the smallest in the Bohai Sea from 1979 to *** the extreme wave height in the northeastern part of taiwan Island shows a significant increase trend in the study *** analysis shows remarkable variations in the values of 50-and 100-year significant wave heights in eight *** the annual mean change,E1,E2,S1,and S2 present an increasing trend,while S3 shows a decreasing *** points for the seasonal mean change demon-strate an increasing trend in spring and winter,while other points show a decreasing trend in summer and ***,the E1 point growth rate is large in autumn,which is related to the change in typhoon intensity and the northward movement of the typhoon path.

关键词： extreme wave height NEVA wave climate ERA5 reanalysis

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Research on Low Voltage Series Arc Fault Prediction Method Based on Multidimensional Time-Frequency Domain Characteristics

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Energy Engineering 2023年第9期120卷 1979-1990页

作者： Feiyan Zhou HuiYin Chen Luo Haixin Tong KunYu Zewen Li Xiangjun Zeng China Electric Power Research Institute Distribution technology center China Electric Power Research InstituteBeijing100192China National Key Laboratory of disaster Prevention and reduction for Power Grid ChangshaUniversity of Science and TechnologyChangsha410114China

The load types in low-voltage distribution systems are *** loads have current signals that are similar to series fault arcs,making it difficult to effectively detect fault arcs during their occurrence and sustained combustion,which can easily lead to serious electrical fire *** address this issue,this paper establishes a fault arc prototype experimental platform,selects multiple commonly used loads for fault arc experiments,and collects data in both normal and fault *** analyzing waveform characteristics and selecting fault discrimination feature indicators,corresponding feature values are extracted for qualitative analysis to explore changes in timefrequency characteristics of current before and after *** features are then selected to form a multidimensional feature vector space to effectively reduce arc misjudgments and construct a fault discrimination feature *** on this,a fault arc hazard prediction model is built using random *** model’s multiple hyperparameters are simultaneously optimized through grid search,aiming tominimize node information entropy and complete model training,thereby enhancing model robustness and generalization *** experimental verification,the proposed method accurately predicts and classifies fault arcs of different load types,with an average accuracy at least 1%higher than that of the commonly used fault predictionmethods compared in the paper.

关键词： Low voltage distribution systems series fault arcing grid search time-frequency characteristics

Key technologies of earthquake early warning system for China’s high-speed railway

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Railway sciences 2024年第2期3卷 239-262页

作者： Geming Zhang Lin Yang Wenxiang Jiang Railway science&technology Research&Development center China Academy of Railway Sciences Corporation LimitedBeijingChina China Academy of Railway sciences Corporation Limited BeijingChina

Purpose–The purpose of this study is to introduce the top-level design ideas and the overall architecture of earthquake early-warning system for high speed railways in China,which is based on P-wave earthquake early-warning and multiple ways of rapid ***/methodology/approach–The paper describes the key technologies that are involved in the development of the system,such as P-wave identification and earthquake early-warning,multi-source seismic information fusion and earthquake emergency treatment *** paper also presents the test results of the system,which show that it has complete functions and its major performance indicators meet the design ***–The study demonstrates that the high speed railways earthquake early-warning system serves as an important technical tool for high speed railways to cope with the threat of earthquake to the operation *** key technical indicators of the system have excellent performance:The first report time of the P-wave is less than three *** the first arrival of P-wave to the beginning of train braking,the total delay of onboard emergency treatment is 3.63 seconds under 95%*** average total delay for power failures triggered by substations is 3.3 ***/value–The paper provides a valuable reference for the research and development of earthquake early-warning system for high speed railways in other countries and *** also contributes to the earthquake prevention and disaster reduction efforts.

关键词： Earthquake early-warning High speed railway China earthquake networks center(CENC) Earthquake emergency treatment

A clipping algorithm for real-scene 3D models

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International Journal of Digital Earth 2023年第1期16卷 464-485页

作者： Jianhua Chen Xu Liu Bingqian Wang Jian Lu College of Geophysics Chengdu University of TechnologyChengduPeople’s Republic of China Chengdu Rescue and disaster reduction technology center ChengduPeople’s Republic of China Sichuan Huadi Construction Engineering Co. Ltd.ChengduPeople’s Republic of China

The development of unmanned aerial vehicle(UAV)oblique photogrammetric technology provides a good foundation for the rapid construction of large-scale and high-definition real-scene 3D ***,due to the limitations of the modeling process,irrelevant feature data cannot be eliminated in the modeling *** built models contain irrelevant features and model distortions caused by *** present,most existing clipping algorithms cannot effectively clip real-scene 3D models that are organized as a whole or with levels of detail(LODs).Therefore,this paper proposes a novel algorithm for clipping real-scene 3D models from any perspective based on clipping boundary lines thatfit the surfaces of the *** results of the clipping experiments for 3D models constructed with oblique UAV images show that this algorithm can effectively clip any part of the 3D models,that the clipping results of each level model closelyfit the corresponding clipping boundary lines,and that the accuracy of the clipping results is very ***,the time complexity of the algorithm is O(n^(2)).In conclusion,the algorithm proposed in this paper provides correct and effective clipping results for real-scene 3D models with LODs that are constructed with photogrammetric or 3D laser scanning data.

关键词： Real-scene 3D models Clip Linesfitting 3D model surfaces Triangular mesh