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Chinese Physics B 2024年第6期33卷 596-603页

作者：吕小龙杨加恩谢航 College of Science Guangxi University of Science and TechnologyLiuzhou 545006China College of Physics Chongqing UniversityChongqing 401331China Chongqing Key laboratory for Strongly-Coupled Physics Chongqing UniversityChongqing 401331China

Topological zero-line modes(zlMs) with spin and valley degrees of freedom give rise to spin, valley and spinvalley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the zlMs in a three-terminal system. we show that with certain combinations of zlMs, the incident charge current al.ng the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the zlMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam ***, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin–orbit coupl.ng. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of zlMs.

关键词： topological zero-line modes spin polarization valley polarization quantum transport

Experimental investigation of hypersonic flight-duplicated shock tunnel characteristics

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Acta Mechanica Sinica 2021年第3期37卷 422-433,I0002页

作者： C K.Yuan z.l.Jiang Institute of Mechanics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

Hypersonic air-breathing propulsion is one of the key techniques for future aviation and the ground aerodynamic testing for full scale test models with sufficient test time at flight conditions is of fundamental importance for verifying hypersonic air-breathing *** on the backward detonation-driven concept,the hypersonic flight-duplicated shock tunnel(or JF-12 shock tunnel)has been successfully constructed and *** facility is capable of reproducing airflow for Mach numbers ranging from 5 to 9 at an altitude of 25-50 km,with a test duration of more than 100 *** quantify the performance of the shock tunnel,experiments were conducted to investigate the aerodynamic characteristics of the test flows and the effects of several critical techniques that play important roles in the operation of the shock *** stagnation pressure was constant within士5%and the average stagnation pressure varied by less than 0.048%/*** variation of the stagnation pressure in repeated experiments is less than 2.0%,indicating the good repeatability of the wind *** non-uniformity of the Mach number in the core flow field at the nozzle exit was within士2.5%.Additional,a uniform flow field is established upstream of the nozzle *** axial gradients of the flow field are small since the Mach number varies less than 1.7%/*** regarding the ignition technology,diaphragm ruptures,detonation driver capacity,incident shock-wave decay,and tunnel operation mode are also *** findings of this study are not only helpful for operating the shock tunnel,but can also assist the future development of hypersonic wind tunnels.

关键词： Hypersonics Shock tunnels Flow characteristics

Overcoming the strength-ductility trade-off by tailoring grain-boundary metastable Si-containing phase in β-type titanium alloy

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Journal of Materials Science & Technology 2021年第9期68卷 112-123页

作者： X.luo l.H.liu C.Yang H.z lu H.w.Ma z.wang D.D.li l.C.zhang Y.Y.li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou510640China State Key laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan430074China Key laboratory of Automobile Materials of MOE Department of Materials ScienceJilin UniversityChangchun130012China School of Engineering Edith Cowan University270Joondalup DriveJoondalupPerthWA 6027Australia

It is well accepted that grain-boundary phases in metallic alloys greatly deteriorate the mechanical *** our work,we report on a novel strategy to prepare high strength-ductility β-type(Ti69.71 Nb23.72zr4.83Ta1.74)97Si3(at.%)(TNzTS) alloys by tailoring grain-boundary metastable Si-containing ***,the thin shell-shaped metastable S1 phase surrounding the columnar β-Ti grain was intercepted successfully via nonequilibrium rapid solidification achieved by selective laser melting(SlM).Subsequently,the thin shell-shaped metastable(Ti,Nb,zr)5 Si3(called S1) phase was transformed into globular(Ti,Nb,zr)2 Si(called S2) phase by the solution heat ***,the globular S2 phases reinforced TNzTS alloy exhibits ultrahigh yield strength of 978 MPa,ultimate strength of 1010 MPa and large el.ngation of 10.4 %,overcoming the strength-ductility trade-off of TNzTS alloys by various ***,the reported yield strength herein is 55 % higher than that of conventionally forged TNzT *** analysis indicates the globularization process of the metastable S1 phase is controlled by the model of termination *** quantitative analysis on strengthening mechanism demonstrates that the increase in yield strength of the heat-treated alloys is mainly ascribed to the strengthening of the precipitated silicide and the dislocations induced by high cool.ng *** obtained results provide some basis guidelines for designing and fabricating β-titanium alloys with excellent mechanical properties,and pave the way for biomedical application of TNzTS alloy by SlM.

关键词： Selective laser melting βtitanium alloys Heat treatment

Evolution mechanisms of microstructure and mechanical properties in a friction stir welded ultrahigh-strength quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第7期102卷 213-223页

作者： z.w.wang J.F.zhang G.M.Xie l.H.wu H.zhang P.Xue D.R.Ni B.l.Xiao z.Y.Ma Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China State Key laboratory of Roll.ng and Automation Northeastern UniversityShenyang110819China

Ultrahigh-strength quenching and partitioning(Q&P) steels have attracted strong interests in the auto manufactory,while the comprehensive understanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their *** the present work,it is designed to make an insight into these imperative *** strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding(FSw) technique under different parameters. Apparent hardening and softening were observed in stir zone(Sz) and heat-affected zone(HAz) respectively,whose microstructures strongly depended on the peak temperature and cool.ng rate during *** formation of fresh martensite was the main mechanism for the Sz hardening,while the decomposition of metastable phases played key roles in the microhardness drop of the HAz.A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength under parameter *** dual-phase structure,nano-carbide particles,tempered initial martensite,and ultrafine-grained ferrite synergistically improved the strain hardening ability of the HAz.which eventually resulted in the equal strength FSw joints.

关键词： Ultrahigh-strength Q&P steel Friction stir welding Microstructure Mechanical property Strain hardening

Microbiological Quality of Cyperus esculentus l. Products Sold in Ouagadougou and Bobo Dioulasso (Burkina Faso)

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Open Journal of Applied Sciences 2024年第3期14卷 635-642页

作者： zénabou Semdé Passinguemsin Alice Sonia Tiendrebeogo Bahanla Edwige Oboulbiga Charles Parkouda Hagrétou Sawadogo l.ngani laboratoire des Sciences et Technologies des Aliments et Nutrition Département technologie alimentaire IRSAT CNRST Ouagadougou Burkina Faso

This study aimed to assess the microbiological quality of tiger nut (Cyperus esculentus l.) products sold in Ouagadougou and Bobo Dioulasso. The microbial load of tubers and tiger nut milk was determined using ISO 4833-1 (2003) standard (total mesophilic aerobic flora), NF ISO 7954 (1998) standard (yeasts and molds), and ISO 4832 (2006) standard (total coliforms, thermotolerant coliforms). The results showed that tiger nut tubers had an average microbial load between 4.86 ± 7.03 × 106 UFC/g and 1.82 ± 2.30 × 107 UFC/g for total mesophilic aerobic flora, from 4.34 ± 10.6 × 105 UFC/g to 3.52 ± 4.54 × 106 UFC/g for yeasts and molds, from 2.23 ± 2.25 × 105 UFC/g to 1.41 ± 2.16 × 105 UFC/g for total coliforms and from 1.83 ± 2.03 × 105 UFC/g to 7.0 ± 10.8 × 104 CFU/g for thermotolerant coliforms. For tiger nut milk samples, the average microbial load varied from 3.48 ± 2.98 × 106 CFU/g to 2.80 ± 5.69 × 107 CFU/g for total mesophilic aerobic flora, from 5.00 ± 7.21 × 104 CFU/g to 1.88 ± 3.31 × 105 CFU/g for yeasts and molds, from 4.58 ± 10.4 × 104 CFU/g to 6.31 ± 9.17 × 105 CFU/g for total coliforms and 7.00 ± 7.00 × 103 CFU/g to 2.87 ± 5.86 × 105 CFU/g for thermotolerant coliforms. This study revealed that the tubers and tiger nut milk sold in Ouagadougou and Bobo Dioulasso had a high microbial load which could lead to the degradation of these products and food poisoning for consumers.

关键词： Cyperus esculentus l. Tiger Nut Tubers Tiger Nut Milk Microbiological Quality

Interaction of oblique waves with an array of l.ng horizontal circular cylinders

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Science China(Technological Sciences) 2007年第4期50卷 490-509页

作者： ng Chiu-On Department of Mechanical Engineering the University of Hong Kong Pokfulam Road Hong Kong China

The scattering and radiations of linear oblique waves by multiple l.ng horizontal circular cylinders submerged in water of finite depth are investigated using the multipole expansion method. Analytical expressions for the diffracted and radiated potentials are given as a linear combination of infinite multipoles. The unknown coefficients in the expressions are determined by using the addition theorem of the Bessel function and the cylinder boundary conditions. Also analytical expressions for wave forces, hydrodynamic coefficients and reflection and transmission coeffi-cients are derived. The present analytical solution is verified through the boundary element method and applied to investigate three different cases of the interaction of oblique waves with multiple submerged horizontal circular cylinders. The results show that the number of cylinders, the arrangement and spacing between cylinders play an important role in wave forces, hydrodynamic coefficients and reflection and transmission coefficients. Some interesting and important phenomena are ob-served in numerical experiments.

关键词： scattering and radiation water waves analytical technique hydrodynamic characteristics

Plasticity-induced stacking fault behaviors ofγ'precipitates in novel CoNi-based superalloys

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Journal of Materials Science & Technology 2021年第31期90卷 20-29页

作者： w.-w.Xu G.H.Yin z.Y.Xiong Q.Yu T.Q.Gang l.J.Chen School of Aerospace Engineering Xiamen UniversityXiamen 361005China

Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a chall.nging task for *** lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based *** put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/w on the plastic deformation mechanism ofγ'precipitates in Co-based *** is found that alloying Ni and adjusting Al/w obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy *** addition of either Ni or w deteriorates the strength even the stability of *** ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated *** for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of *** theoretical results agree with the available measurements and well capture the observed phenomena in experiments.

关键词： Co-based superalloys Stacking fault energy Creep resistance First-principles method

Microstructural evolution and mechanical properties of NiCrAlYSi+NiAl/cBN abrasive coating coated superalloy during cyclic oxidation

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Journal of Materials Science & Technology 2021年第12期71卷 44-54页

作者： Y.D.liu J.Sun w.li w.S.Gu z.l.Pei J.Gong C.Sun School of Materials Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China Institute of Metal Research Chinese Academy of Sciences72 Wenhua RoadShenyang 110016China Advanced Research Institute for Multidisciplinary Science Qilu University of Technology(Shandong Academy of Sciences)3501 Daxue RoadJinan 250353China

Cyclic oxidation behavior of Ni Cr Al YSi+Ni Al/c BN abrasive coating at 900°C and the mechanical properties of the coating-substrate system were *** indicated that elemental interdiffusion occurred between the coating and substrate,which caused the formation of interdiffusion zone(IDz)and secondary reaction zone(SRz)during aluminization,while their compositions and structures changed with *** N interfacial layer formed at c BN/metallic matrix interface during aluminization,while it transformed into multilayer oxides during *** to the microstructural evolution of these interfaces,the fracture behavior and bending toughness of the system changed greatly during three-point bending ***,the damage mechanisms were discussed.

关键词： Abrasive coating Cyclic oxidation TEM Interface Superalloy

Observation and Simulation of n=1 Reversed Shear Alfvén Eigenmode on the Hl-2A Tokamak

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Chinese Physics letters 2022年第10期39卷 26-33页

作者： P.w.Shi Y.R.Yang w.Chen z.B.Shi z.C.Yang l.M.Yu T.B.wang X.X.He X.Q.Ji w.l.zhong M.Xu X.R.Duan Southwestern Institute of Physics Chengdu 610041China State Key laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi’an 710024China

A branch of high-frequency Alfvenic modes is observed on the Hl-2A *** electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam *** mode frequency keeps almost unchanged or presents a slow-sweeping behavior,depending on the detail current *** poloidal and toroidal mode numbers are𝑚m/n=1/*** mode has a quite short duration(≤20 ms)and usually appears 5-10 ms after the neutral beam being injected into the *** simulations based on M3D-K have also been carried *** result suggests that co-passing energetic particles are responsible for the mode *** simulated mode structures are localized nearby location of minimum safety factor(q_(min))and agree with the structures obtained through tomography of soft x-ray ***,the modes are localized in the continuum gap and their frequencies increase with variation of𝑞min in a wide *** but not least,the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety *** those evidences indicate that the𝑛n=1 high-frequency mode may bel.ng to a reversed shear Alfven eigenmode.

关键词： Alfven mode unchanged

Oxidation,Mechanical and Tribological Behaviors of the Ni/cBN Abrasive Coating-Coated Titanium Alloys

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Acta Metallurgica Sinica(English letters) 2021年第7期34卷 1007-1020页

作者： Y.D.liu J.H.liu w.S.Gu H.l.li w.H.li z.l.Pei J.Gong C.Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the seal.ng performance of the gas turbine engine,a Ni/cBN abrasive coating was prepared on titanium alloys through composite ***,mechanical and tribological properties of the abrasive coating were ***,the effect of the oxidation on the mechanical and tribological properties was also *** results revealed that the abrasive coating underwent slight oxidation within 700℃.Meanwhile,some intermetallic compounds,Ni3Ti,NiTi and NiTi2,were formed at the coating/substrate interface during *** to the pinning effect of cBN particles and the different thermal expansion coefficients of the coating and substrate,the coating/substrate interface was cracked after oxidation at 700℃.Tensile results showed that the presence of coating reduced the strength of the alloy significantly at room temperature,while only marginal variations of the strength of the coated and uncoated specimens at elevated ***,the wear tests indicated that the coating had the excellent cutting ability and wear resistance,which can effectively protect the blades tip of titanium *** the temperature increased,the wear resistance decreased due to the decrease in the mechanical properties of the Ni/cBN coating.

关键词： Abrasive coating Oxidation Mechanical properties wear Titanium alloy