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Achieving ultrahigh strength and ductility in high-entropy alloys via dual precipitation

Journal of Materials Science & technology 2023年第35期166卷 67-77页

作者： J.M.Guo B.C.Zhou S.Qiu h.J.Kong M.C.Niu J.h.Luan t.L.Zhang h.wu Z.B.Jiao Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong KongChina the hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Department of Materials Science and Engineering City University of Hong KongHong KongChina State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

the strength-ductility trade-offhas been a longstanding dilemma in metallic *** we report an innovative approach to achieve a high strength-ductility synergy via dual precipitation of sheared and bypassed precipitates.(Ni_(2) Co_(2) FeCr)_(96-x) Al_(4) Nb_(x)(at.%)alloys strengthened by nanoscale L12 particles and Laves precipitates were selected as a model for this study,and their precipitate microstructures and mechanical properties were thoroughly *** dual-precipitation-strengthened alloys exhibit a yield strength of more than 1400 MPa,an ultimate tensile strength of over 1800 MPa,and a uniform elon-gation of 18%,thus achieving a high strength-ductility *** analysis reveals that the nanoscale L1_(2) precipitates contribute to the strength via the particle shearing mechanism,whereas the Laves phase provides the strengthening through the Orowan bypass *** study of deformation microstruc-tures shows that the L1_(2) precipitates are sheared by stacking faults,which facilitates long-range disloca-tion gliding through the *** a result,deformation induces the formation of hierarchical stacking fault networks and immobile Lomer-Cottrell locks,which effectively enhance the work hardening ca-pability and plastic stability,thereby resulting in a high ductility at high strength *** are piled-up against the interface between the Laves precipitates and matrix,which increases the work hardening capability at the early stages of plastic deformation but causes stress *** dual precipitation strategy may be useful for many other alloys for achieving superior mechanical properties for technological applications.

关键词： high-entropy alloy Dual precipitation Precipitation strengthening Deformation mechanism

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Electro-optical properties and(E,F) phase diagram of fluorinated chiral smectic liquid crystals

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Chinese Physics B 2018年第10期27卷 570-577页

作者： R Zgueb h Dhaouadi t Othman Universite tunis El-Manar Faculte des Sciences de Tunis Laboratoire de physique de la matiere molle et de modelisation electromagnetique (LP3ME) Campus Universitaire Farhat Hached 2092 Tunis Tunisie

Fluorinated smectic liquid crystals each with a biphenyl benzoate rigid core are investigated. Molecular structures of the studied compounds have difference only in fluorine position and the length of the carbon chain. Dielectric relaxation study and electro-optical measurements are carried out with the classical SSFLC geometry. the field-induced phase transitions are studied and the（E,t） phase diagram is established.

关键词： smectic liquid crystal dielectric relaxation electro-optical properties phase transition (E,t)phase diagram

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Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

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Journal of Materials Science & technology 2018年第1期34卷 192-197页

作者： L.h. wu K. Nagatsuka K. Nakata Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

Oxygen-flee copper （Cu） was successfully joined to carbon-fiber-reinforced thermoplastic （CFRtP, polyamide 6 with 20wt% carbon fiber addition） by friction lap joining （FLJ） at joining speeds of 200-1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 ram. It is the first time to report the joining of CFRtP to Cu by FLJ. As the joining speed increased, the tensile shear force （tSF） of joints increased first, and decreased thereafter. the maximum tSF could reach 2.3 kN （ 15 mm in width）. hydrogen bonding formed between the amide group of CFRtP and the thin Cu20 layer on the Cu surface, which mainly contributed to the joint bonding. the influence factors of the tSF of the joints at different joining speeds were discussed. the tSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows： the joining area increased first and then decreased; the degra- dation of the plastic matrix and the number and the size of bubbles decreased. the maximum tSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.

关键词： Friction lap joining Metal Plastic Carbon-fiber reinforced thermoplastic Dissimilar materials joining

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Large signal of h → μτ within the constraints of e_(i) → e_(j)γ decays in the 3-3-1 model with neutral leptons

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Chinese Physics C 2022年第12期46卷 106-125页

作者： h.t.hung D.t.Binh h.V.Quyet Department of Physics Hanoi Pedagogical University 2Phuc YenVinh Phuc 15000Vietnam Institute of theoretical and Applied Research Duy Tan UniversityHanoi 10000Vietnam Faculty of Natural Science Duy Tan UniversityDa Nang 50000Vietnam

In the framework of the 3-3-1 model with neutral leptons,we investigate lepton-flavor-violating sources based on the higgs mass spectrum,which has two neutral higgs identified with the corresponding ones of the two-higgs-doublet *** note that at the 13teV scale of the LhC,the parameter space regions satisfy the experimental limits of e_(i)→e_(j)γ*** regions depend heavily on the mixing of exotic leptons but are predicted to have large h_(1)^(0)→μτ*** also show that Br(h_(1)^(0)→μτ)can reach a value of 10^(-4).

关键词： higgs boson electroweak interaction beyond the SM LFV decays

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USING hIGh Mg-CONtENt CORED-WIRE tO SPhEROIDIZE AND DESULPhURIZE DUCtILE IRON MELt IN INDUStRIAL EXPERIMENtS

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 881-887页

作者： R.Z.wu B.D.Sun h.J.Ni Y.B.wu h.S.wu J.G.Ge theStateKeyLaboratoryofMetalMatrixComposites ShanghaiJiaotongUniversityShanghai200030China theCollegeofMaterialScience＆Engineering HarbinUniversityofScience＆TechnologyHarbin150080China FoundryBranch HarbinDong＇anEngineCo.Ltd.Harbin150066China

Mg-content cored-wire was used to desulphurize and spheroidize ductile iron melt in industrial experiments. the optimal feeding speed and suitable treatment temperature were determined in the experiments. And cored-wire method and pouring method were compared. Conclusions have been drawn that, under these conditions in the experiments, the optimal feeding speed is 15m/min, treatment temperature should be as low as possible, 1400-1450℃ generally; and cored-wire method can act more effective in ductile iron melt desulphurization and spheroid than pouring method.

关键词： high Mg-content cored-wire cored-wire method spheroid desulphurization

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A DNA delivery system containing listeriolys in Oresults in enhanced hepatocytedirected gene expression

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World Journal of Gastroenterology 1999年第6期5卷 465-469页

作者： Cherie M. Walton, Catherine h. wu and George Y. wu Department of Medicine Division of Gastroenterology-Hepatology University of Connecticut Health Center Farmington CT United States Department of Medicine Division of Gastroenterology-Hepatology University of Connecticut Health Center Farmington CT 06030 United States

AIM to determine whether incorporation of the ph dependent bacterial toxin listeriolysin O (LLO) into the DNA carrier system could increase the endosomal escape of internalized DNA and result gene expression. MEthODS A multi component delivery system was prepared consisting of asialoglycoprotein (ASG), poly L lysine (PL), and LLO. two marker genes, luciferase and β galactosidase in plasmids were complexed and administered in vitro to huh7[ASG receptor (+) ] and SK hep1[ASG receptor (-) ] cells. Purity, hemolytic activity, gene expression, specificity, and toxicity were evaluated. RESULtS An LLO containing conjugate retained cell targeting specificity and membranolytic activity. In ASG receptor (+) cells, luciferase gene expression was enhanced by more than 7 fold over that of conjugates without the incorporation of listeriolysin O. No significant expression occurred in ASG receptor (-) cells. Enhancement of β galactosidase gene expression was less, but still significantly increased over controls. there was no detectable toxicity at concentrations shown to be effective in transfection studies. CONCLUSIONS ASOR PL can be coupled to LLO using disulfide bonds, and successfully target and increase the gene expression of foreign DNA.

关键词： DNA gene expression listeriolysin O hepatocytes

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Molecular Dynamics Simulation of tensile Deformation and Fracture of γ-tiAl with and without Surface Defects

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Journal of Materials Science & technology 2016年第10期32卷 1033-1042页

作者： h.N.wu D.S.Xu h.Wang R.Yang Institute of Metal Research Chinese Academy of Sciences

Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-tiAl single *** results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. the defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-tiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. the dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. the effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. this simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of tiAl if well controlled.

关键词： Intermetallic compounds Superdislocation Fracture Surface defects Molecular dynamics

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Data-Driven Fault Detection of Multiple Open-Circuit Faults for MMC Systems Based on Long Short-term Memory Networks

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1563-1574页

作者： Chenxi Fan Kaishun Xiahou Lei Wang Q.h.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

this paper presents a long short-term memory(LStM)-based fault detection method to detect the multiple open-circuit switch faults of modular multilevel converter(MMC)systems with full-bridge sub-modules(FB-SMs).Eighteen sensor signals of grid voltages,grid currents and capacitance voltages of MMC for single and multi-switch faults are collected as sampling *** output signal characteristics of four types of single switch faults of FB-SM,as well as double switch faults in the same and different phases of MMC,are analyzed under the conditions of load variations and control command changes.A multi-layer LStM network is devised to deeply extract the fault characteristics of MMC under different faults and operation conditions,and a Softmax layer detects the fault *** results have confirmed that the proposed LStM-based method has better detection performance compared with three other methods:K-nearest neighbor(KNN),naive bayes(NB)and recurrent neural network(RNN).In addition,it is highly robust to model uncertainties and Gaussian *** validity of the proposed method is further demonstrated by experiment studies conducted on a hardware-in-the-loop(hIL)testing platform.

关键词： Fault detection long short-term memory(LStM) modular multilevel converter(MMC) open circuit fault

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Location of Asymmetric Ground Fault Using Virtual Injected Current Ratio and two-stage Recovery Strategy in Distribution Networks

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 151-161页

作者： haiting Shan Luliang Zhang Q.h.wu Mengshi Li School of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

Sparse measurements challenge fault location in distribution *** paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).the relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint the ***,a two-stage recovery strategy is proposed for improving reconstruction accuracy of the current vector,where two different sensing matrixes are utilized to improve the *** proposed method is validated in IEEE 34 node test *** results show asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our *** addition,it works effectively under various scenarios of noisy measurement and line parameter *** on 134 node test feeders prove the proposed method is also suitable for systems with more complex structure.

关键词： Distribution networks fault location reconstruction accuracy two-stage recovery virtual injected current ratio

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Achieving superior mechanical properties in friction lap joints of copper to carbon-fiber-reinforced plastic by tool offsetting

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Journal of Materials Science & technology 2018年第9期34卷 1628-1637页

作者： L.h.wu K.Nagatsuka K.Nakata Joining and Welding Research Institute Osaka University

It is a challenge to achieve a sound welded metal/carbon-fiber-reinforced thermoplastic（CFRtP） joint with high strength and few bubbles. In this study, sound lap joints of Cu and CFRtP were obtained by friction lap joining（FLJ） directly at rotation rates of 600-2000 rpm, with the welding tool at the joint center and offsetting the tool 7 mm away from the center toward the retreating side, respectively. tool offsetting reduced the non-uniform temperature distribution in the lap joints resulting from the high conductivity of Cu, which not only enhanced the tensile shear force from 0.89-2.25 kN to 1.71-3.54 kN,with the maximum increasing rate of 135%, but also reduced the bubble area to only 19% of the original level of 2000 rpm. It is the first time to report a high-quality Cu/CFRtP joint with a high strength and few bubbles. the large increase of the strength after tool offsetting was attributed to the increase of the joining area, the decrease of bubbles and the decrease of the CFRtP degradation. the details on the generation,quantitative distribution and expulsion of the bubbles in the FLJ joints were discussed.

关键词： hybrid joining Plastic Metal Carbon-fiber-reinforced plastic Properties

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