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Influence of welded pores on fatigue behavior of TC17 titanium alloy welded joints subjected to gigacycle regime at room and high temperatures

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Journal of Materials Science & Technology 2024年第11期178卷 1-21页

作者： Fulin liu Yao Chen Lang Li Chong Wang Qingyuan Wang yongjie liu MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province Sichuan UniversityChengdu 610207China Department of Mechanical Engineering Kyushu UniversityFukuoka 819-0395Japan

Welded structures in aero-engines commonly operate in high-temperature environments,making them susceptible to reduced fatigue life and premature failure due to welding defects within the ***,the gigacycle fatigue behaviors of titanium alloy welded joints at both room temperature(RT)and 400 ℃ were investigated,aiming to uncover the mechanism behind the formation of fine granular area(FGA)surrounding welded *** research findings demonstrate that the S-N curves of TC17 tita-nium alloy electron beam welded joint undergo a transition from a single linear decline at RT to a bilin-ear decline at 400 ℃.However,the fatigue failure mode remains unaffected by temperatures,and crack initiation is attributed to welded *** utilizing the Chapetti model curve to modify the Kitagawa-Takahashi(K-T)diagram,the lower threshold stress amplitude is introduced,enabling the determination of a safe size for welded pores at 400 ℃,which is calculated to be 11.3 μ***,the Gumbel probability distribution function is employed to assess the maximum size of welded ***,based on dislocation interactions,the formation mechanism of the FGA consisting of discontinuous nanograins with high-density dislocations is elucidated.

关键词： Titanium alloy Welded joints Gigacycle fatigue Welded pores High temperature Fine granular area

Review on degradation mechanism and health state estimation methods of lithium-ion batteries

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第4期10卷 578-610页

作者： Yongtao liu Chuanpan liu yongjie liu Feiran Sun Jie Qiao Ting Xu School of Automobile Chang'an UniversityXi'an 710064China College of Transportation Engineering Chang'an UniversityXian 710064China

State of health(SOH)estimation is important for a lithium-ion battery(LIB)health state management system,and accurate estimation of SOH is influenced by the degree of degradation of the ***,considering the complex electrochemical reactions within Li electrons and the influence of many external factors on internal reactions,it is difficult to accurately estimate the SOH based on the surface state characteristics of the battery(including current,voltage,and temperature).Thus,in this study,the knowledge graph method is employed to analyze keyword co-occurrences and citations in the literature on LIB degradation and SOH estimation to determine research *** on the research trends,findings regarding the internal and external degradation mechanisms and influencing factors of(LIBs)are reorganized,and chemical and physical degradation processes,including solid electrolyte interface(SEI)layer formation,fracture,Li plating,and dendrite formation,are systematically introduced based on the modeling *** interrelationships between these degradation factors and their effects on capacity and power decay as well as their correlation with SOH estimation are ***,a comparative analysis of existing SOH estimation methods is presented,and the applicable scenarios and technical problems of each method are *** key issues such as model simplification,estimation methods based on random data,and second-life SOH are also analyzed and *** results show that the estimation results of methods mixing multiple models tend to be more ***,the development trend of SOH estimation methods under complex degradation conditions and usage scenarios is analytically discussed.

关键词： Lithium-ion battery Stateof health Estimation Degradation Knowledge graph

Effect of ultrasonic peening treatment on the fatigue behaviors of a magnesium alloy up to very high cycle regime

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Journal of Magnesium and Alloys 2022年第3期10卷 659-673页

作者： Yao Chen Fulin liu Chao He Lang Li Chong Wang yongjie liu Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province Sichuan UniversityChengdu 610065China MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China

Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation ***,crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation *** initiate as Mode Ⅱ crack within the original grain,but deflect to Mode I crack outside of the original cracked grain.A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack *** of the original cracked grain,Mode I crack propagation below the threshold ΔK_(σ-th) is responsible for the formation of fine granular area(FGA,a nano-grain layer).Based on the Numerous Cyclic Pressing(NCP) model,it is proposed that crack type should be another necessary condition for the formation of FGA.

关键词： Ultrasonic peening treatment Very-high-cycle fatigue Crack initiation mechanism Fine granular area Nanograins.

Effect of long-period stacking ordered structure on very high cycle fatigue properties of Mg-Gd-Y-Zn-Zr alloys

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Journal of Magnesium and Alloys 2023年第8期11卷 2811-2822页

作者： Xiangyu WANG Chao HE Xue Li Lang LI yongjie liu Qingyuan WANG Key Laboratory of Deep Earth Science and Engineering Ministry of EducationCollege of Architecture and EnvironmentSichuan UniversityChengdu 610065China Failure Mechanics&Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China School of Architecture and Civil Engineering Chengdu UniversityChengdu 610106China

Magnesium alloys with a long-period stacking ordered(LPSO)structure usually possess excellent static strength,but their fatigue behaviors are poorly *** work presents the effect of the LPSO structure on the crack behaviors of Mg alloys in a very high cycle fatigue(VHCF)*** LPSO lamellas lead to a facet-like cracking process along the basal planes at the crack initiation site and strongly prohibit the early crack propagation by deflecting the growth *** stress intensity factor at the periphery of the faceted area is much higher than the conventional LPSO-free Mg alloys,contributing higher fatigue crack propagation threshold of LPSO-containing Mg *** observation at the facets reveals a layer of ultrafine grains at the fracture surface due to the cyclic contact of the crack surface,which supports the numerous cyclic pressing model describing the VHCF crack initiation behavior.

关键词： Fatigue crack initiation Long-period stacking ordered structure Mg alloys Ultrafine grains Very high cycle fatigue

Determining origins of satellite breakup events in LEO region

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Astrodynamics 2023年第4期7卷 465-476页

作者： yongjie liu Yu Jiang Hengnian Li Zongbo Huyan Hongchao Wang State Key Laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'an 710043China

Currently,a surge in the number of spacecraft and fragments is observed,leading to more frequent breakup events in low Earth orbits(LEOs).The causes of these events are being identified,and specific triggers,such as collisions or explosions,are being examined for their importance to space traffic *** propagation methods were employed to trace the origins of these types of breakup *** were conducted using the NASA standard breakup model,and satellite Hitomi’s breakup was ***-Leibler(KL)divergences,Euclidean 2-norms,and Jensen-Shannon(JS)divergences were computed to deduce potential types of breakups and the associated fragmentation *** the simulated case,a discrepancy of 22.12 s between the estimated and actual time was ***,the breakup of the Hitomi satellite was estimated to have occurred around UTC 1:49:26.4 on March 26,*** contrasts with the epoch provided by the Joint Space Operation Center,which was estimated to be at 1:42 UTC±11 *** the findings,it was suggested that the techniques introduced in the study can be effectively used to trace the origins of short-term breakup events and to deduce the types of collisions and fragmentation masses under certain conditions.

关键词： breakup collision explosion Kullback-Leibler(KL)divergence Jensen-Shannon(JS)divergence

African Swine Fever Virus MGF-110-9L-deficient Mutant Has Attenuated Virulence in Pigs

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Virologica Sinica 2021年第2期36卷 187-195页

作者： Dan Li Yinguang liu Xiaolan Qi Yuan Wen Pan Li Zhao Ma yongjie liu Haixue Zheng Zhijie liu State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory Lanzhou Veterinary Research InstituteChinese Academy of Agricultural SciencesLanzhou 730046China

African swine fever virus(ASFV)is the etiological agent of African swine fever(ASF),an often lethal disease in domestic and wild *** represents a major threat to the swine industry ***,no commercial vaccine is available because of the complexity of ASFV or biosecurity *** attenuated viruses that are naturally isolated or genetically manipulated have demonstrated reliable protection against homologous ASFV strain *** the present study,a mutant ASFV strain with the deletion of ASFV MGF-110-9L(ASFV-D9L)was generated from a highly virulent ASFV CN/GS/2018 parental strain,a genotypeⅡ*** to the parental ASFV isolate,deletion of the MGF-110-9L gene significantly decreased the ability of ASFV-D9L to replicate in vitro in primary swine macrophage cell *** majority of animals inoculated intramuscularly with a low dose of ASFV-D9L(10 HAD50)remained clinically normal during the 21-day observational *** of five ASFV-D9L-infected animals displayed low viremia titers and low virus shedding and developed a strong virus-specific antibody response,indicating partial attenuation of the ASFV-D9L strain in *** findings imply the potential usefulness of the ASFV-D9L strain for further development of ASF control measures.

关键词： African swine fever virus(ASFV) MGF-110-9L Mutant Attenuated virulence Pig

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Effects of three-dimensional soil heterogeneity on seed germination in controlled experiments

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Journal of Plant Ecology 2021年第1期14卷 1-9页

作者： yongjie liu Fujiang Hou State Key Laboratory of Grassland Agro-ecosystems Key Laboratory of Grassland Livestock Industry InnovationMinistry of Agriculture and Rural AffairsCollege of Pastoral Agriculture Science and TechnologyLanzhou UniversityLanzhou 730020China

Aims Seed germinations react to their local growing conditions,but the impacts of soil heterogeneity on seed germinations are not well *** Effects of three-dimensional soil heterogeneity on seed germinations of grasses species were explored,where two levels of such soil heterogeneity were created via alternatively filling nutrient-poor and nutrientrich substrate in pot in all *** sizes of the two heterogeneity levels are around 7.5 and 15 cm,*** seeds of each of the grasses species(Lolium perenne and Elymus nutans)were set either in these heterogeneous soils or in petri dishes with distilled *** germinations of these species were daily *** Findings We found that pots with smaller patches had relatively lower germination rate,which is con sistent with our expectati on that shorter distance between nutrient-rich and nu trient-poor patches in pots with smaller patches allows plants to reduce their germination rates and delay their germination,in order to reduce the negative impacts of the strong variation of soil resources in these *** results also revealed that pots with smaller patches yielded more heterogeneous seed germination,*** germinations highly diverged among these *** findings highlight that the realistic three-dimensional design can improve our understanding of seed germination as driven by soil spatial heterogeneity.

关键词： seed germination soil heterogeneity patch plant species three dimensions

Streptavidin-Biotin Complexes as Tools for Modulating an Important DNA Episgenetic Modification

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Chinese Journal of Chemistry 2024年第18期42卷 2166-2172页

作者： yongjie liu Xinyan Xu Xingyu liu Wei Xiong Qianqian Qi Yuanyuan Zhang Jinxuan Hou Tian Tian Xiang Zhoua Key Laboratory of Biomedical Polymers of Ministry of Education College of Chemistry and Molecular SciencesHubei Province Key Laboratory of Allergyand ImmunologyWuhan UniversityWuhanHubei 430072China Department of Thyroid&Breast Surgery Zhongnan Hospital of Wuhan UniversityWuhan UniversityWuhanHubei 430072China

DNA 5-formylcytosine(5fC)is a prominent epigenetic modification within biological *** investigations have shed light on its pivotal role in governing cell fate,gene expression,and disease ***,our comprehension of the precise control of the 5f site structure to influence its functionality remains *** this study,we have successfully achieved precise control over 5fc activity by harnessing the interaction between streptavidin and *** research underscores the potential application of interactions between biomacromolecules and small molecules in advancing the field of DNA epigenetic functional regulation.

关键词： Epigenetic modification Biotin Streptavidin Selectivity Regulation

Comparisons on Mineralogy and Lithology between Paleozoic Marine and Lacustrine Dolostones, Northern China

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Acta Geologica Sinica(English Edition) 2017年第S1期91卷 281-282页

作者： LI Hong liu Yiqun NIU Yuanzhe FENG Shihai LEI Yun liu yongjie State Key Laboratory of Continental Dynamics(Northwest University) Xi’an710069

1 Introduction Dolomite[Ca Mg(CO3)2],a common mineral in carbonate rocks,can be found in various geological settings from Precambrian to modern age,and is widely reported in almost all sedimentary and digenetic

关键词： Comparisons on Mineralogy and Lithology between Paleozoic Marine and Lacustrine Dolostones Northern China