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Joined AZ31B Magnesium Alloys with Ag Interlayer by Ultrasonic-Induced Transient Liquid Phase Bonding in air

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1177-1185页

作者： Qian Wang Peng Yu Haoran Lin Chongzhi guo Xiaoqiang hu Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341119China School of Rare Earths University of Science and Technology of ChinaHefei230026China Shenyang 7D New Materials Equipment Co.LTD. Shenyang110076China Shenyang National Laboratory of Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

AZ31B magnesium alloys are commonly used in lightweight structures of automobile and aerospace *** this work,the ultrasonic-induced transient liquid phase bonding technique is deployed to joint AZ31B magnesium alloys at 490℃ with Ag interlayer in the *** effect of ultrasonic vibration on microstructure and mechanical properties of welding seam is *** vibration duration increases,the width of the welding seam increases firstly and then *** the ultrasound vibration sustained for one second,the eutectic reaction occurred in the contacting interface between Ag interlayer and the base metal AZ31B,resulting in formation of liquid phase and metallurgical *** the ultrasound vibration sustained for seven second,the width of the welding seam increased to a maximum of about 303.1μm and the average shear bond strength of the welding joint attained the peak value of about 66.87 *** the ultrasound vibration sustained over seven seconds,the liquid phase is gradually squeezed out and the width of the welding seam decreases.α-Mg and AgMg_(3) can be observed in the welding *** analysis shows thatα-Mg has a certain strengthening *** whole process of appearance,growth and integration ofα-Mg is analyzed.

关键词： Ultrasonic bonding Magnesium alloy Silver Microstructure Intermetallic compound

FlockSeer:A portable stereo vision observer for bird flocking

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IET Cyber-Systems and Robotics 2024年第3期6卷 74-86页

作者： Yuhui ai Haozhou Zhai Zijie Sun Weiming Yan Tianjiang hu School of Artificial Intelligence Sun Yat‐sen UniversityZhuhaiChina School of Aeronautics and Astronautics Sun Yatsen UniversityShenzhenChina

Bird flocking is a paradigmatic case of self‐organised collective behaviours in *** camera systems are employed to observe flocks of starlings,jackdaws,and chimney swifts,mainly on a spot‐fixed basis.A portable non‐fixed stereo vision‐based flocking observation system,namely FlockSeer,is developed by the authors for observing more species of bird flocks within field *** portable flocking observer,FlockSeer,responds to the challenges in extrinsic calibration,camera synchronisation and field movability compared to existing spot‐fixed observing systems.A measurement and sensor fusion approach is utilised for rapid calibration,and a light‐based synchronisation approach is used to simplify hardware *** has been implemented and tested across six cities in three provinces and has accomplished diverse flock‐tracking tasks,accumulating behavioural data of four species,including egrets,with up to 300 resolvable *** authors reconstructed the trajectories of a flock of egrets under disturbed conditions to verify the practicality and *** addition,we analysed the accuracy of identifying nearest neighbours,and then examined the similarity between the trajectories and the Couzin *** results demonstrate that the developed flocking observing system is highly portable,more convenient and swift to deploy in wetland‐like or coast‐like *** observation process is reliable and practical and can effectively support the study of understanding and modelling of bird flocking behaviours.

关键词： avian flight camera calibration camera system collective behaviour stereo vision

Glacial-interglacial cycles recorded in clay minerals from the eastern Tibetan Plateau over the last 800 ka and their indications

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Science China Earth Sciences 2024年第7期67卷 2162-2177页

作者： Xiaoyan ZHANG Chunxia ZHANG Yan ZHAO Bin hu Zhengtang guo Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Clay mineral proxies have been widely used to reconstruct changes in provenance and the ***,high-altitude clay mineral indications and long-term and orbital variations have not been fully ***,we present an800-ka clay-mineral record from a lacustrine sediment core(ZB13-C2)from the Zoige Basin on the eastern Tibetan Plateau(TP).X-ray diffraction and scanning electron microscopy were used to identify the clay mineral assemblages and their micromorphological characteristics of core *** results revealed that the clay minerals in core ZB13-C2 are mainly illite,with small amounts of chlorite,kaolinite,and smectite(including irregular mixed-layers of illite-smectite(I/S)and chloritesmectite(C/S)).The clay mineral assemblages and proxies exhibit three stages of change,which are mainly controlled by the Zoige watershed range under different climate *** watershed was limited to the southeastern region with altitudes ranging from~3500 to~4200 meters above sea level(m a.s.l.),and glacial-interglacial hydraulic erosion controlled the input of bedrock debris during 800-621 ka *** expanded to higher altitudes(~4200 to~4700 m a.s.l.)due to stronger seasonal freezethaw weathering without significant glacial-interglacial variations under a cooling and drying climate during 621-100 ka ***,it expanded to its highest altitudes of~4700 to~5200 m *** of the watershed after 100 ka BP,and hydraulic erosion increased obviously under a warm climate of the interstadial MIS 3 on the *** watershed underwent two major expansions under different climatic conditions at~621 ka and 100 ka BP,with the wet/dry alternation became strong at~621 ka *** results reveal that long-term temperature changes and the wet/dry alternation at high altitudes controlled the watershed range and degree of the physical erosion,and that the indications of clay minerals should be carefully clarified before they are used as climate indicators,especi

关键词： Quaternary Zoige Basin Lacustrine sediments Paleoenvironment Weathering

Steam reforming of acetic acid over Ni/biochar of low metal-loading:Involvement of biochar in tailoring reaction intermediates renders superior catalytic performance

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Chinese Journal of Chemical Engineering 2024年第4期68卷 241-252页

作者： Yunyu guo Yiran Wang Shu Zhang Yi Wang Song hu Jun Xiang Walid Nabgan Xun hu School of Material Science and Engineering University of JinanJinan 250022China Joint International Research Laboratory of Biomass Energy and Materials College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan 430074China Departament d'Enginyeria Química Universitat Rovira i VirgiliTarragona 43007Spain

Biochar is a reactive carrier as it may be partially gasified with steam in steam reforming,which could influence the formation of reaction intermediates and modify catalytic ***,the Ni/biochar as well as two comparative catalysts,Ni/Al_(2)O_(3) and Ni/SiO_(2),with low nickel loading(2%(mass))was conducted to probe involvement of the varied carriers in the steam *** results indicated that the Ni/biochar performed excellent catalytic activity than Ni/SiO_(2) and Ni/Al_(2)O_(3),as the biochar carrier facilitated quick conversion of the -OH from dissociation of steam to gasify the oxygen-rich carbonaceous intermediates like C=O and C-O-C,resulting in low coverage while high exposure of nickel species for maintaining the superior catalytic *** converse,strong adsorption of aliphatic intermediates over Ni/Al_(2)O_(3) and Ni/SiO_(2) induced serious coking with polymeric coke as the main type(21.5%and 32.1%,respectively),which was significantly higher than that over Ni/biochar(3.9%).The coke over Ni/biochar was mainly aromatic or catalytic type with nanotube morphology and high *** high resistivity of Ni/biochar towards coking was due to the balance between formation of coke and gasification of coke and partially biochar with steam,which created developed mesopores in spent Ni/biochar while the coke blocked pores in Ni/Al_(2)O_(3) and Ni/SiO_(2) catalysts.

关键词： Steam reforming Acetic acid Ni/biochar catalyst Property of coke Reaction intermediates

Ramsey Numbers of Trees Versus Multiple Copies of Books

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 600-612页

作者： Xiao-bing guo Si-nan hu Yue-jian PENG School of Mathematical Sciences Luoyang Normal UniversityLuoyang 471934China School of Mathematics Hunan UniversityChangsha 410082China

Given two graphs G and H,the Ramsey number R(G,H) is the minimum integer N such that any two-coloring of the edges of K_(N) in red or blue yields a red G or a blue *** v(G) be the number of vertices of G and χ(G) be the chromatic number of *** s(G) denote the chromatic surplus of G,the number of vertices in a minimum color class among all proper χ(G)-colorings of *** showed that R(G,H)≥(v(G)-1)(χ(H)-1)+s(H) if G is connected and v(G)≥s(H).A connected graph G is H-good if R(G,H)=(v(G)-1)(χ(H)-1)+s(H).Let tH denote the disjoint union of t copies of graph H,and let G∨H denote the join of G and *** a complete graph on n vertices by K_(n),and a tree on n vertices by T_(n).Denote a book with n pages by B_(n),i.e.,the join K_(2) ∨■.Erd?s,Faudree,Rousseau and Schelp proved that T_(n) is B_(m)-good if n≥*** this paper,we obtain the exact Ramsey number of T_(n) versus 2B_(2).Our result implies that T_(n) is 2B_(2)-good if n≥5.

关键词： ramsey number ramsey goodness tree book

Mg-Al-hydrotalcite with alkaline sites protects Ni/KIT-6 from formation of amorphous coke in glycerol steam reforming via tailoring reaction intermediates

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Frontiers of Chemical Science and Engineering 2024年第4期18卷 25-39页

作者： Yunyu guo Yiran Wang Yuewen Shao Shu Zhang Yi Wang Song hu Jun Xiang Xun hu School of Material Science and Engineering University of JinanJinan 250022China Joint International Research Laboratory of Biomass Energy and Materials College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan 430074China

During steam reforming,the performance of a catalyst and amount/property of coke are closely related to reaction intermediates reaching surface of a ***,modification of reaction intermediates by placing Mg-Al-hydrotalcite above Ni/KIT-6 catalyst in steam reforming of glycerol was conducted at 300 to 600°*** results revealed that the catalytic activity of Ni/KIT-6 in the lower bed was enhanced with either Mg1-Al5-hydrotalcite(containing more acidic sites)or Mg5-Al1-hydrotalcite(containing more alkaline sites)as upper-layer *** in situ infrared characterization of steam reforming demonstrated that Mg-Al-hydrotalcite catalyzed the deoxygenation of glycerol,facilitating the reforming of the partially deoxygenated intermediates over Ni/***-Al-hydrotalcite as protective catalyst,however,did not protect the Ni/KIT-6 from formation of more ***,this did not lead to further deactivation of Ni/KIT-6 while Mg5-Al1-hydrotalcite even substantially enhanced the catalytic stability,even though the coke was much more significant than that in the use of single Ni/KIT-6(52.7%vs.28.6%).The reason beneath this was change of the property of coke from more aliphatic to more ***5-Al1-hydrotalcite catalyzed dehydration of glycerol,producing dominantly reaction intermediates bearing C=C,which formed the catalytic coke of with carbon nanotube as the main form with smooth outer walls as well as higher aromaticity,C/H ratio,crystallinity,crystal carbon size,thermal stability,and resistivity toward oxidation on Ni/KIT-6 in the lower *** comparison,the abundance of acidic sites on Mg1-Al5-hydrotalcite catalyzed the formation of more oxygen-containing species,leading to the formation of carbon nanotubes of rough surface on Ni/KIT-6.

关键词： steam reforming of glycerol Mg-Alhydrotalcite sacrificial catalyst reaction intermediates property of coke

Ferrite features in simulated transition zone of EH36 shipbuilding steel submerged arc welded by CaF_(2)-SiO_(2)-MnO fluxes

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Journal of Iron and Steel Research International 2024年第4期31卷 790-796页

作者： Ming Zhong Dong hu Da-ming guo Somnath Basu Cong Wang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Department of Metallurgical Engineering and Materials Science Indian Institute of Technology BombayMumbai 400076MaharashtraIndia

Ferrite features in the simulated transition zone welded with CaF_(2)-SiO_(2)-MnO fluxes containing various MnO contents have been *** laser scanning microscopy has been applied to simulate the thermal cycling of the transition zone and the phase transformations during cooling have been in-situ *** has been found that the appearance temperature for ferrite side plate decreases with increasing Mn content in the weld metals caused by MnO content ***,growth rates for both ferrite side plate and acicular ferrite are significantly enhanced with a higher Mn content of weld ***,from the statistical fractions of salient microstructures,for all samples,the acicular ferrite,grain boundary ferrite,and polygonal ferrite take over more than 90%.It has also been demonstrated that with the increase in Mn content,the ferrite side plate fraction increases slightly from 5%to 10%and the acicular ferrite fraction shows a tendency of first increasing and then decreasing,which experiences the maximum with the flux containing 30 wt.%*** phenomenon is believed to be controlled by the O and Mn contents in weld metals synergistically.

关键词： Submerged arc welding Transition zone Phase transformation Microstructure

Solid solution strategy modulated defects engineering of(Cr_(1-x)V_(x))_(2)AlC MAX phase toward superior electromagnetic wave absorption

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Rare Metals 2024年第7期43卷 3205-3219页

作者： Ji-Lin Gou Yu-Kai Chang Shu Liu Peng-hui Li Ping-Hao Cui Qian-Ku hu Li-Bo Wang Xin Zhang Jun-Kai Wang Qi-Xun Xia ai-guo Zhou School of Materials Science and Engineering Henan Polytechnic UniversityJiaozuo 454003China Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China

Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave(EMW)absorption ***,the relationship between them is not clear,especially in solid solution *** this work,a series of(Cr_(1-x)V_(x))_(2)AlC MAX phase solid solutions with layered structure were prepared via tuning the ratio of Cr and V to explore their EMW absorption *** experimental results indicated that the doping of V atoms at the M-site could effectively regulate its impedance matching and EMW absorption properties by introducing appropriate numbers of defects in the crystal,such as twin boundaries,dislocations and lattice *** them,if Cr:V=3:1,Cr_(1.5)V_(0.5)AlC,as radar absorption materials,could reach a strong reflection loss of-51.8 dB at the frequency of 12.8 GHz under an ultra-thin thickness of 1.3 *** reflection loss value could attain-10 dB in a wide frequency range of 2.7-18 GHz and thickness range of 1-5 *** addition,after high temperature and acid-alkali immersion treatment,this sample still had good EMW absorption capability,and the effective absorption bandwidth was enhanced from 2.3 to 2.6 GHz after concentrated acid immersion or 3.1 GHz after concentrated alkali *** work has great reference significance for the research and development of high-performance MAX-based EMW absorption materials in harsh environments.

关键词： MAX phases Solid solution Defects engineering Electromagnetic wave absorption Harsh environments

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α-氨基酸的不对称合成

高等学校化学学报 2001年第3期22卷 421-430页

作者：胡爱国王善韦韩军王积涛南开大学化学系南开大学测试中心天津300071

α-氨基酸的不对称合成是合成方法学中的重要组成部分 ,由此而发展出来的方法成为不对称合成领域中的典范 .本文着重从合成方法学角度出发 ,总结了α-氨基酸不对称合成的最新进展 .

关键词：合成方法学 α-氨基酸不对称合成 α,β-去氢氨基酸衍生物氢化反应甘氨酸类似物亲电反应