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Modified Coffin-Manson equation to predict the fatigue life of structural materials subjected to mechanical-thermal coupling non-coaxial loading

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Journal of Materials Science & Technology 2023年第29期160卷 118-127页

作者： Zhichao Ma chaofan li Wei Zhang Shenghui Wang Jiakai li Hongwei Zhao Luquan Ren School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130025China Key Laboratory of CNC Equipment Reliability Ministry of EducationJilin UniversityChangchun 130025China Key Laboratory of Bionic Engineering Ministry of Education Jilin UniversityChangchun 130025China

With regard to the structures subjected to severe mechanical-thermal coupling fatigue conditions,the consistency between service conditions and loading conditions was the prerequisite for the fatigue prop-erties test and fatigue life prediction.A miniature piezoelectric-driven instrument integrating with a tripodal piezoelectric actuator and envelope-type heating function was developed to investigate the mechanical-thermal coupling fatigue properties and obtain the fatigue life of materials under approximate service conditions.A physical model was described to quantitatively calculate the alternating deformation under the mechanical-thermal coupling tensile-bending combined ***,a fatigue life prediction method based on the Coffin-Manson equation under tensile-bending combined loading was proposed to estimate the mechanical-thermal coupling fatigue life in terms of the total coupling defor-mation and plastic strain *** feasibility of the proposed instrument was verified through the analysis of displacement responses of high entropy alloy specimens under the thermal-mechanical cou-pling tensile-bending combined condition at temperatures ranging from RT to 600°*** comparison between fatigue lives directly measured through thermal-mechanical coupling experiments and theoreti-cally predicted fatigue lives indicated the availability of the modified Coffin-Manson equation.

关键词： Fatigue testing instrument Mechanical-thermal coupling Combined loading Fatigue life prediction odified Coffin-Manson equation

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Predictable and Unpredictable Components of the Summer East Asia–Pacific Teleconnection Pattern

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Advances in Atmospheric Sciences 2018年第11期35卷 1372-1380页

作者： Xiaozhen liN chaofan li Riyu LU Adam A.SCAIFE State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100029China Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Met Oce Hadley Centre FitzRoy RoadExeter EX1 3PBUK College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeterDevon EX4 4QF UK

The East Asia–Pacific(EAP) teleconnection pattern is the dominant mode of circulation variability during boreal summer over the western North Pacific and East Asia, extending from the tropics to high latitudes. However, much of this pattern is absent in multi-model ensemble mean forecasts, characterized by very weak circulation anomalies in the mid and high latitudes. This study focuses on the absence of the EAP pattern in the extratropics, using state-of-the-art coupled seasonal forecast systems. The results indicate that the extratropical circulation is much less predictable, and lies in the large spread among different ensemble members, implying a large contribution from atmospheric internal variability. However,the tropical–mid-latitude teleconnections are also relatively weaker in models than observations, which also contributes to the failure of prediction of the extratropical circulation. Further results indicate that the extratropical EAP pattern varies closely with the anomalous surface temperatures in eastern Russia, which also show low predictability. This unpredictable circulation–surface temperature connection associated with the EAP pattern can also modulate the East Asian rainband.

关键词： EAP pattern circulation seasonal forecast surface temperature eastern Russia

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Modeling grassland net primary productivity and water-use efficiency along an elevational gradient of the Northern Tianshan Mountains

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Journal of Arid Land 2013年第3期5卷 354-365页

作者： QiFei HAN GePing LUO chaofan li Hui YE Yaoliang CHEN State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences University of Chinese Academy of Sciences

Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and cli- rnatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosys- tem-climate interactions is vital for mountainous ecosystems. Water-use efficiency （WUE） provides a useful index for understanding the metabolism of terrestrial ecosystems as well as for evaluating the degradation of grasslands. This paper explored net primary productivity （NPP） and WUE in grasslands along an elevational gradient ranging from 400 to 3,400 m asl in the northern Tianshan Mountains-southern Junggar Basin （TMJB）, Xinjiang of China, using the Biome-BGC model. The results showed that： 1 ） the NPP increased by 0.05 g C/（m2-a） with every increase of 1-m elevation, reached the maximum at the mid-high elevation （1,600 m asl）, and then decreased by 0.06 g C/（m2.a） per 1-m increase in elevation; 2） the grassland NPP was positively correlated with temperature in alpine meadow （AM, 2,700-3,500 m asl）, mid-mountain forest meadow （MMFM, 1,650-2,700 m asl） and low-mountain dry grassland （LMDG, 650-1,650 m asl）, while positive correlations were found between NPP and annual precipitation in plain desert grassland （PDG, lower than 650 m asl）; 3） an increase （from 0.08 to 1.09 g C/（m2.a）） in mean NPP for the grassland in TMJB under a real climate change scenario was observed from 1959 to 2009; and 4） remarkable differences in WUE were found among different elevations, in general, WUE increased with decreasing elevation, because water availability is lower at lower elevations; however, at elevations lower than 540 m asl, we did observe a decreasing trend of WUE with decreasing elevation, which may be due to the sharp changes in canopy cover over this gradient. Our research suggests that the NPP simulated by Biome-BGC is consistent with field data, and the modeling provides an opportunity to further evaluate interactions between environmental factors and ecosystem

关键词： elevational gradient net primary production water-use efficiency climate

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A spatial-explicit dynamic vegetation model that couples carbon,water,and nitrogen processes for arid and semiarid ecosystems

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Journal of Arid Land 2013年第1期5卷 102-117页

作者： Chi ZHANG chaofan li Xi CHEN GePing LUO LongHui li XiaoYu li Yan YAN Hua SHAO State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China University of the Chinese Academy of Sciences Beijing 100049 China

Arid and semiarid ecosystems, or dryland, are important to global biogeochemical cycles. Dryland＇s community structure and vegetation dynamics as well as biogeochemical cycles are sensitive to changes in climate and atmospheric composition. Vegetation dynamic models has been applied in global change studies, but the com- plex interactions among the carbon （C）, water, and nitrogen （N） cycles have not been adequately addressed in the current models. In this study, a process-based vegetation dynamic model was developed to study the responses of dryland ecosystems to environmental changes, emphasizing on the interactions among the C, water, and N proc- esses. To address the interactions between the C and water processes, it not only considers the effects of annual precipitation on vegetation distribution and soil moisture on organic matter （SOM） decomposition, but also explicitly models root competition for water and the water compensation processes. To address the interactions between C and N processes, it models the soil inorganic mater processes, such as N mineralization/immobilization, denitrifica- tion/nitrification, and N leaching, as well as the root competition for soil N. The model was parameterized for major plant functional types and evaluated against field observations.

关键词： process-based model arid ecosystem C cycle vegetation dynamics

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Micro/nano-mechanical behaviors of individual FCC,BCC and FCC/BCC interphase in a high-entropy alloy

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Journal of Materials Science & Technology 2022年第19期114卷 102-110页

作者： Wei Zhang Zhichao Ma chaofan li Chaowei Guo Dongni liu Hongwei Zhao Luquan Ren School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130025China Key Laboratory of CNC Equipment Reliability Ministry of EducationJilin UniversityChangchun 130025China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory of Bionic Engineering Ministry of Education Jilin UniversityChangchun 130025China Weihai Institute for Bionics Jilin UniversityWeihai 264207China

Here,a systematic investigation was made on the interphase strengthening effects induced superior me-chanical performances of multiphase high-entropy alloys(HEAs)at micro/nano-scale,compared with sin-gle phase HEAs.A pillar compression test under a scanning electron microscope(SEM)was performed on the individual face centered cubic(FCC),body centered cubic(BCC),and mixed-phases with different di-ameters in a Fe_(24)Co_(25)Ni_(24)Cr_(23)Al_(4)HEA using focused ion beam(FIB)milling and a nanoindenter equipped with a flat *** stress-strain response of pillar underneath the indenter was selected to explore the diameter/phase-dependent size effect,the periodically fluctuation of local stress,and strain *** was revealed that the pillars at the interphase exhibited significantly higher strength,compared with the FCC and BCC *** experiment also verified the coincident mechanical size effects independent with the type of *** stress responses in the mixed-phase pillars manifested as a distinct transition from the dramatic drop to the minor fluctuation during the post-yield stages with the increasing strain,indicating the propagation of Al-Ni enriched solid solution phase(BCC1)under *** the BCC1 phase,numerous dislocations were observed in the post-deformed pillars,particularly serving as the major source to enhance the strain hardening of BCC pillars.

关键词： Size effect Stress fluctuation Compression Interphase High-entropy alloys

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Skilful Forecasts of Summer Rainfall in the Yangtze River Basin from November

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Advances in Atmospheric Sciences 2023年第11期40卷 2082-2091页

作者： Philip E.BETT Nick DUNSTONE Nicola GOLDING Doug SMITH chaofan li Met Office Hadley Centre FitzRoy RoadExeter EX13PBUK Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049China

Variability in the East Asian summer monsoon(EASM)brings the risk of heavy flooding or drought to the Yangtze River basin,with potentially devastating *** forecasts of the likelihood of enhanced or reduced monsoon rainfall can enable better management of water and hydropower resources by decision-makers,supporting livelihoods and major economic and population centres across eastern *** paper demonstrates that the EASM is predictable in a dynamical forecast model from the preceding November,and that this allows skilful forecasts of summer mean rainfall in the Yangtze River basin at a lead time of six *** skill for May–June–July rainfall is of a similar magnitude to seasonal forecasts initialised in spring,although the skill in June–July–August is much weaker and not consistently ***,there is some evidence for enhanced skill following El Niño *** potential for decadal-scale variability in forecast skill is also examined,although we find no evidence for significant variation.

关键词： seasonal forecasting interannual forecasting flood forecasting Yangtze basin rainfall East Asian summer monsoon

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The Seasonal Prediction of the Exceptional Yangtze River Rainfall in Summer 2020

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Advances in Atmospheric Sciences 2021年第12期38卷 2055-2066页

作者： chaofan li Riyu LU Nick DUNSTONE Adam ASCAIFE Philip EBETT Fei ZHENG Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of the Chinese Academy of Sciences Beijing 100029China Met Office Hadley Centre FitzRoy RoadExeter EX13PBUK College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeterDevon EX44QFUK International Center for Climate and Environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

During June and July of 2020,the Yangtze River basin suffered from extreme mei-yu rainfall and catastrophic *** study explores the seasonal predictability and associated dynamical causes for this extreme Yangtze River rainfall event,based on forecasts from the Met Office GloSea5 operational forecast *** forecasts successfully predicted above-average rainfall over the Yangtze River basin,which arose from the successful reproduction of the anomalous western North Pacific subtropical high(WNPSH).Our results indicate that both the Indian Ocean warm sea surface temperature(SST)and local WNP SST gradient were responsible for the westward extension of the WNPSH,and the forecasts captured these tropical signals *** explore extratropical drivers but find a large model spread among the forecast members regarding the meridional displacements of the East Asian mid-latitude westerly jet(EAJ).The forecast members with an evident southward displacement of the EAJ favored more extreme Yangtze River ***,the forecast Yangtze River rainfall anomaly was weaker compared to that was observed and no member showed such strong *** observations,the EAJ displayed an evident acceleration in summer 2020,which could lead to a significant wind convergence in the lower troposphere around the Yangtze River basin,and favor more mei-yu *** model forecast failed to satisfactorily reproduce these *** difference implies that the observed enhancement of the EAJ intensity gave a large boost to the Yangtze River rainfall,hindering a better forecast of the intensity of the event and disaster mitigation.

关键词： seasonal forecast Yangtze River rainfall western North Pacific subtropical high westerly jet

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Variation in the permafrost active layer over the Tibetan Plateau during 1980–2020

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Atmospheric and Oceanic Science Letters 2024年第5期17卷 34-39页

作者： Jinglong Huang chaofan li Binghao Jia Chujie Gao Ruichao li College of Oceanography Hohai UniversityNanjingChina Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijingChina

The active layer,acting as an intermediary of water and heat exchange between permafrost and atmosphere,greatly influences biogeochemical cycles in permafrost areas and is notably sensitive to climate *** the Chinese Meteorological Forcing Dataset to drive the Community Land Model,version 5.0,this study simulates the spatial and temporal characteristics of active layer thickness(ALT)on the Tibetan Plateau(TP)from 1980 to *** show that the ALT,primarily observed in the central and western parts of the TP where there are insufficient station observations,exhibits significant interdecadal changes after *** average thickness on the TP decreases from 2.54 m during 1980–1999 to 2.28 m during 2000–*** change is mainly observed in the western permafrost region,displaying a sharp regional inconsistency compared to the eastern region.A persistent increasing trend of ALT is found in the eastern permafrost region,rather than an interdecadal *** aforementioned changes in ALT are closely tied to the variations in the surrounding atmospheric environment,particularly air ***,the area of the active layer on the TP displays a profound interdecadal change around 2000,arising from the permafrost thawing and *** consistently decreases before 2000 but barely changes after *** regional variation in the permafrost active layer over the TP revealed in this study indicates a complex response of the contemporary climate under global warming.

关键词： Active layer thickness Permafrost Tibetan plateau Climatological characteristics

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Skillful Seasonal Forecasts of Summer Surface Air Temperature in Western China by Global Seasonal Forecast System Version 5

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Advances in Atmospheric Sciences 2018年第8期35卷 59-68页

作者： chaofan li Riyu LU Philip E. BETT Adam A. SCAIFE Nicola MARTIN Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China University of the Chinese Academy of Sciences Beijing 100029 China Met Office Hadley Centre FitzRoy Road Exeter EX1 3PB UK College of Engineering Mathematics and Physical Sciences University of Exeter Exeter Devon EX4 4QF UK

Variations of surface air temperature （SAT） are key in affecting the hydrological cycle, ecosystems and agriculture in western China in summer. This study assesses the seasonal forecast skill and reliability of SAT in western China, using the GloSea5 operational forecast system from the UK Met Office. Useful predictions are demonstrated, with considerable skill over most regions of western China. The temporal correlation coefficients of SAT between model predictions and observations axe larger than 0.6, in both northwestern China and the Tibetan Plateau. There are two important sources of skill for these predictions in western China： interannual variation of SST in the western Pacific and the SST trend in the tropical Pacific. The tropical SST change in the recent two decades, with a warming in the western Pacific and cooling in the eastern Pacific, which is reproduced well by the forecast system, provides a large contribution to the skill of SAT in northwestern China. Additionally, the interannual variation of SST in the western Pacific gives rise to the reliable prediction of SAT around the Tibetan Plateau. It modulates convection around the Maritime Continent and further modulates the variation of SAT on the Tibetan Plateau via the surrounding circulation. This process is evident irrespective of detrending both in observations and the model predictions, and acts as a source of skill in predictions for the Tibetan Plateau. The predictability and reliability demonstrated in this study is potentially useful for climate services providing early warning of extreme climate events and could imply useful economic benefits.

关键词： seasonal forecast western China surface air temperature predictability warming trend

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Beclin-1/LC3-II dependent macroautophagy was uninfluenced in ischemia-challenged vascular endothelial cells

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Genes & Diseases 2022年第2期9卷 549-561页

作者： Yaping Ma chaofan li Yan He Tiwei Fu li Song Qingsong Ye Fugui Zhang Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences Chongqing 401147PR China Department of Oral and Maxillofacial Surgery Stomatological Hospital of Chongqing Medical UniversityChongqing 401147PR China Tianyou Hospital Wuhan University of Science&TechnologyWuhanHubei 430064PR China Department of Oral and Maxillofacial Surgery Massachusetts General HospitalBostonMA 02114USA Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education Chongqing 401147PR China Center for Regenerative Medicine Renmin Hospital of Wuhan UniversityWuhanHubei 430060PR China

Autophagy has been extensively studied and occurs in many biological ***,a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells,as has been previously ***,the effect of the level of autophagy on cell or skin flap survival still requires *** created a lethal ischemia model in human umbilical vascular endothelial cells(HUVECs),performed quantitative proteomics and bioinformatics analyses,and verified the autophagic status and effect both in vitro and in *** significantly upregulated proteins encoded by autophagy-related genes(ATGs)included ATG2A,ATG3,ATG4B,ATG5,ATG7,ATG9A,ATG12,ATG16,and *** significantly enhanced lysosomal proteins were cathepsin B,cathepsin D,lysosome-associated membrane protein 1(LAMP1),and ***,the differentially expressed proteins excluded Beclin-1,microtubule-associated protein light chain 3(LC3)-I,and *** blot analyses verified that the protein expression levels of Beclin-1,LC3-I,and LC3-II were neither upregulated nor downregulated in ischemia-challenged *** autophagic status was not enhanced by rapamycin in ischemic HUVECs but appeared to be inhibited by *** in vivo study on rats showed that a downregulation in autophagic status jeopardized skin flap *** conclusion,Ischemia neither enhanced nor inhibited Beclin-1/LC3-II-dependent canonical macroautophagy both in vitro and in vivo,in contradiction to previous *** appropriate autophagic homeostasis can minimize cell or skin flap damage.

关键词： Autophagy Bioinformatics analysis Human umbilical vein endothelial cell Quantitative proteomics study Skin flap

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