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Critical current degradation in an epoxy-impregnated rare-earth Ba_(2)Cu_(3)O_(7-x)coated conductor caused by damage during a quench

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1557-1572页

作者： Dongh.i LiU huadong yong Youhe ZhOU institute of Superconductor Mechanics Lanzhou UniversityLanzhou 730000China Department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of ChinaLanzhou UniversityLanzhou 730000China

high-temperature superconducting(hTS)rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductors(CCs)have significant potential in high-current and high-field ***,owing to the weak interface strength of the laminated composite REBCO CCs,the damage induced by the thermal mismatch stress under a combination of epoxy impregnation,cooling,and quenching can cause premature degradation of the critical *** this study,a three-dimensional(3D)electromagnetic-thermal-mechanical model based on the h-formulation and cohesive zone model(CZM)is developed to study the critical current degradation characteristics in an epoxy-impregnated REBCO CC caused by the damage during a *** temperature variation,critical current degradation of the REBCO CC,and its degradation onset temperature calculated by the numerical model are in agreement with the experimental data taken from the *** delamination of the REBCO CC predicted by the numerical model is consistent with the experimental *** numerical results also indicate that the shear stress is the main contributor to the damage propagation inside the REBCO *** premature degradation of the critical current during a quench.is closely related to the interface shear strength.inside the REBCO ***,the effects of the coefficient of thermal expansion(CTE)of the epoxy resin,thickness of the substrate,and substrate material on the critical current degradation characteristics of the epoxy-impregnated REBCO CC during a quench are also *** results help us understand the relationship between the current-carrying degradation and damage in the hTS applications.

关键词： epoxy-impregnated rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductor(CC) quench damage critical current degradation shear stress

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Quantum Tunneling Enhanced hydrogen Desorption from Graphene Surface: Atomic versus Molecular Mechanism

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Chinese Physics Letters 2024年第8期41卷 58-68页

作者： Yangwu Tong yong Yang Science island Branch of Graduate School University of Science and Technology of ChinaHefei 230026China Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China

We study the desorption mechanism of hydrogen isotopes from graphene surface using first-principles calculations,with focus on the effects of quantum *** low temperatures,quantum tunneling plays a dominant role in the desorption process of both hydrogen monomers and *** the case of dimer desorption,two types of mechanisms,namely the traditional one-step desorption in the form of molecules(molecular mechanism),and the two-step desorption in the form of individual atoms(atomic mechanism),are studied and *** the ortho-dimers,the dominant desorption mechanism is found to switch from the molecular mechanism to the atomic mechanism above a critical temperature,which.is∼300K and 200K for h and D,respectively.

关键词： desorption quantum mechanism

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highly efficient and wearable thermoelectric composites based on carbon nanotube film/polyaniline

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Journal of Materiomics 2024年第1期10卷 173-178页

作者： Jing huang Xiaohua Liu yong Du School of Materials Science and Engineering Shanghai Institute of Technology100 Haiquan RoadShanghai201418China

Polyaniline(PANi)was prepared by in-situ polymerization and compounded on the two-dimensional network structural multi-walled carbon nanotube film(CNTF).Compared with the CNT/PANi composites fabricated by using CNT powders or dispersions,the compact and continuous network structure of CNTF/PANi is beneficial to both the thermoelectric and mechanical properties of the *** resultant CNTF/PANi composites with PANi polymerization time of 5 h obtain an electrical conductivity of 1338.4 S/cm and Seebeck coefficient of 63.3μV/K at 360 K,which are 168.7%and 5.7%higher than those of the CNTF(498.1 S/cm and 59.9μV/K at 360 K).Consequently,a maximum power factor of 536.8μW·m^(−1)·K^(−2) at 360 K is acquired,which.is about 2 times higher than that of CNTF(181.7μW·m^(−1)·K^(−2) at 360 K).The electrical conductivity of the composites could maintain 93.3%after being bent for 500 times,indicating the excellent *** tensile strength,Young's Modulus and toughness of CNTF/PANi composites(232.3 MPa,3.6 GPa and 20.1 MJ/m^(3),respectively)are 3.5,2.6 and 2.1 times of those of the *** flexible,free-standing,lightweight and high-strength CNTF/PANi composites reveal the excellent thermoelectric performance,which are promising in the applications in wearable thermoelectric devices.

关键词： Carbon nanotube film Polyaniline Thermoelectric performance Mechanical properties

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A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states

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international Journal of Mining Science and Technology 2024年第4期34卷 461-477页

作者： Rui yong Changshuo Wang Nick Barton Shigui Du institute of Rock Mechanics Ningbo UniversityNingbo 315211China Nick Barton&Associates Fjordveien 65cHøvik 1363Norway

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage ***,existing tech.iques often require specialized equipment and skilled operators,posing practical *** this study,a cost-effective photogrammetric approach.is ***,local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock ***/pull tests are conducted on rock joints with varying roughness levels to induce different contact states.A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry *** certain deviations exist,the measured evolution of void geometry is generally consistent with the qualitative findings of previous *** photogrammetric measurements yield comparable accuracy to laser scanning,with maximum errors of 13.2%for aperture and 14.4%for void *** joint matching coefficient(JMC)measurement errors are below 20%.Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2,but even in cases where measurement errors exceed 80%,the maximum JMC error is only ***,the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

关键词： Rock joint Void geometry evolution Photogrammetry Aperture Void volume Joint matching coefficient

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The KAM theorem on the modulus of continuity about parameters

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Science China Mathematics 2024年第3期67卷 577-592页

作者： Zhicheng Tong Jiayin Du yong Li School of Mathematics Jilin UniversityChangchun 130012China institute of Mathematics Jilin UniversityChangchun 130012China School of Mathematics and Statistics Center for Mathematics and Interdisciplinary SciencesNortheast Normal UniversityChangchun 130024China

in this paper,we study the hamiltonian systems h(y,x,ξ,ε)=〈ω(ξ),y〉+εP(y,x,ξ,ε),where ω and P are continuous about ξ.We prove that persistent invariant tori possess the same frequency as the unperturbed tori,under a certain transversality condition and a weak convexity condition for the frequency mapping ω.As a direct application,we prove a Kolmogorov-Arnold-Moser(KAM) theorem when the perturbation P holds arbitrary holder continuity with respect to the parameter ξ.The infinite-dimensional case is also *** our knowledge,this is the first approach to the systems with the only continuity in the parameter beyond h?lder's type.

关键词： hamiltonian systems invariant tori frequency-preserving weak regularity

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Concentration breaking on two optimization problems

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Science China Mathematics 2024年第7期67卷 1555-1570页

作者： yong huang Qinfeng Li Qiuqi Li School of Mathematics Hunan UniversityChangsha410082China

in the present paper, we study the boundary concentration-breaking phenomena on two thermal insulation problems considered on Lipschitz domains, based on Serrin's overdetermined result, the perturbation argument, and a comparison of Laplacian eigenvalues with different boundary conditions. Since neither of the functionals in the two problems is C^(1), another key ingredient is to obtain the global h?lder regularity of minimizers of both problems on Lipschitz domains. Also, the exact dependence on the domain of breaking thresholds is given in the first problem, and the breaking values are obtained in the second problem on ball domains, which are related to 2π in dimension 2.

关键词： spectral inequalities symmetry breaking Laplacian eigenvalue

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Constructing Lithium-Free Anode/Separator interface via 3D Carbon Fabric Scaffold for Ultrasafe Lithium Metal Batteries

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Research 2024年第3期2023卷 359-368页

作者： Dongdong Li Shengchen Yang Zijian Zheng Wen-yong Lai State Key Laboratory of Organic Electronics and information Displays(SKLOEiD) Institute of Advanced Materials(IAM)School of Chemistry and Life SciencesNanjing University of Posts and Telecommunications9 Wenyuan RoadNanjing 210023China Department of Materials Chemistry Huzhou University1 Xueshi RoadHuzhou 313000China Laboratory for Advanced interfacial Materials and Devices School of Fashion and TextilesDepartment of Applied Biology and Chemical TechnologyResearch Institute for Intelligent Wearable Systems(RI-IWEAR)Research Institute for Smart Energy(RISE)The Hong Kong Polytechnic UniversityHong Kong SAR 999077China

Metallic lithium represents a promising anode candidate to be utilized in future high-energy lithium ***,the undesirable dendrite growth and fragile solid-electrolyte interphase(SEi)pose critical challenge for pursuing further practical *** contrast to traditional approaches of using inert/lithiophilicity coating,here,we demonstrate a reverse strategy of introducing a highly conductive and lithophobic carbon fabric(CF)scaffold on lithium foil to guide a favorable nucleation site of lithium far away from the anode/separator *** CF scaffold with high conductivity can couple with.inner electric field for achieving a uniform distribution of the lithium-ion flux,while the lithophobic feature offers the condition to guide the preferred deposition of lithium onto the underlying lithium foil,which greatly reduces the risk of dendrite-induced short ***,the SEi immersed in the CF scaffold is well supported by CF fibers and therefore exhibits extremely high stability during charge–discharge *** a result,the lithium/CF anodes show>2,000-h stable cycling at 0.5 mA cm−*** metal batteries equipped with our lithium/CF anode deliver a high capacity retention of~99.99%per cycle,i.e.,retain~97.3%capacity after 200 *** unique interface-regulation strategy is versatile for various conductive scaffolds(e.g.,ultrathin and ultralight conductive fabrics),exhibiting high superiority for highly safe lithium metal batteries.

关键词： lithium equipped versatile

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Microstructures and mechanical properties of laser-directed energy deposited CrCoNi medium-entropy alloy

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Rare Metals 2024年第7期43卷 3286-3300页

作者： Wen-Jie Zhao Chang-Yu Liu Peng-Cheng Che Zhi-Liang Ning hong-Bo Fan Jian-Fei Sun yong-Jiang huang Alfonso h.W.Ngan National Key Laboratory for Precision hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Space Environment Simulation Research.infrastructure Harbin Institute of TechnologyHarbin 150001China Department of Mechanical Engineering The University of Hong KongHong Kong 999077China

The distinctive intrinsic heat treatment(ihT)originating from cyclic reheating in the laser-directed energy deposition(LDED) has attracted growing attention in recent *** this investigation,simulations and experimental characterizations were performed to examine the impact of ihT on the micros true ture and mechanical properties of LDED-fabricated CrCoNi medium-entropy alloy(MEA).The results show that the intensity of the ihT is proportional to the utilized laser energy density(LED).As the LED increased,significant dynamic recrystallization and grain refinement occurred within the alloy due to the enhanced intensity of ***,the high LED leads to severe hot cracking within the as-built MEA,resulting in inferior *** decreasing LED,the hot cracking was effectively ***,low LED weakened the intensity of ihT and consequently inhibited kinetic conditions of dynamic recrystallization,resulting in a heterogeneous grain structure characterized by multi-scale-sized *** structure provides significant hetero-deformation-induced hardening during plastic deformation,enabling the alloy to have a sustainable work-hardening *** expect that this work will have implications in taking full advantage of the unique ihT of the LDED process to fabricate ME As with excellent metallurgical quality and mechanical performance.

关键词： intrinsic heat treatment Laser-directed energy deposition CrCoNi MEA Dynamic recrystallization heterogeneous grain structure

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Engineering the interface Between Au Nanoparticles and CoO-Ov to Enhance the Catalytic Performance of 5-hydroxymethylfurfural(hMF)to 2,5-Dimethylfuran(DMF)

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Chemical Research.in Chinese Universities 2024年第1期40卷 47-54页

作者： XiANG Shuang GUO yong LiU Xiaoh.i WANG Yanqin Key Laboratory for Advanced Materials and Joint international Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterResearch Institute of Industrial CatalysisSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237P.R.China

The interface between Au and support has attracted extensive interest because of its unique catalytic ability for hydrogen activation in catalytic hydrogenation/hydrogenolysis ***,we create the Au-CoO-OV interface in the 1.0%Au/Co3O4-Rod-250 catalyst,which could dissociate h2 via the heterolytic way to yield rich hydride species and achieve excellent catalytic performance in the hydrogenolysis of biomass-derived 5-hydroxymethylfurfural(hMF)to 2,5-dimethylfuran(DMF).The XRD and hRTEM analyses show that Au nanoparticles are uniformly dispersed on CoO-OV surface and in situ DRiFTS spectra show the enhancement of heterolytic dissociation of hydrogen(signals of Au-D and O-D vibration)compared with bare CoO(Co3O4-Rod-250).This work provides insights for fabricating highly active Au-support catalysts for catalytic hydrogenation/hydrogenolysis reactions.

关键词： Au-CoO-OV interface hydride species heterolytic dissociation 5-hydroxymethylfurfural(hMF) 2 5-Dimethylfuran(DMF)

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Ligand-controlled Nih-catalyzed regiodivergent hydroalkylation of 2-alkenylazaarenes

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Science China Chemistry 2024年第6期67卷 1935-1940页

作者： Ya-Ping Shao Zhuo-Min Chi yong-Min Liang State Key Laboratory of Applied Organic Chemistry School of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou730000China

A nickel-hydride(Ni h)-catalyzed migratory and nonmigratory hydroalkylation reaction of 2-alkenyl azaarenes with alkyl iodines has been established through strategic modulation of N-or P-donor *** method enables the synthesis of diverseβ-orγ-branched aromatic *** mild regiodivergent protocols exhibit wide substrate scope,excellent functional tolerance,and great reaction yield with remarkable ***,deuterium labeling studies reveal Ni h-catalyzed interrupted ch.in-walking mode as the mechanism behind remotedβ-selective hydroalkylation reaction—an interesting phenomenon mediated through aromatic imine directing groups.

关键词： Nih regiodivergent hydroalkylation azaarenes interrupted ch.in-walking

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