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Pressure and Discharge-Voltage Dependence of Self-Sustaining Pulses in Air-Glow Discharge

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Chinese Physics Letters 2012年第5期29卷 181-184页

作者： A.A.Azooz y.A.Al-Jawaady Z.t.Ali Department of Physics College of ScienceMosul UniversityMosulIraq

the details of formation of micro discharges in air-glow discharge plasma are experimentally *** number of micro discharges formed per second is strongly related to both pressure and discharge *** number tends to show reflections of the Patchen curve as far as its pressure dependence is *** dischargevoltage dependence indicates that the transition from normal to abnormal glow discharge is not a sudden one,but has its roots during the normal glow stage and is initiated by the micro discharges which can be regarded as the early stage of abnormal glow.

关键词： details initiated roots

Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L. seedlings

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Journal of Environmental Sciences 2008年第2期20卷 199-206页

作者： N Dinakar P C Nagajyothi S Suresh y Udaykiran t Damodharam Department of Environmental Sciences Sri Venkateswara UniversityTirupatiAndhra Pradesh-517 502India.

Phytotoxicity of cadmium on growing Arachis hypogaea L. seedlings was studied. Seeds were exposed to 25, 50, and 100 μmol/L CdCl2 concentrations, for a period of 10, 15, 20 and 25 d. the extent of damage to chlorophyll, protein, proline, nitrate and nitrite reductase, antioxidant enzyme activity in leaves and roots were evaluated after 10 d of cadmium stress. the higher concentration of cadmium （100 μmol/L） resulted （leaves and roots） total chlorophyll 91.01%, protein 79.51%, 83.61%, nitrate reductase 79.39%, 80.72% and nitrite reductase 77.07%, 75.88% activity decreased with increase in cadmium concentrations and exposure periods. Cadmium caused significant changes in the activity of antioxidative enzymes. Contrastingly Cd treated plant tissues showed an increase in proline 159.87%, 239.6%, gluthion reductase （GR） 337.72%, 306.14%, superoxide disumutase （SOD） 688.56%, 381.72%, ascorbate peroxidase （APX） 226.47%, 252.14%, peroxidase （POD） 72.19%, 60.29% and catalase （CAt） 228.96%, 214.74% as compared to control. Cadmium stress caused a significant increase in the rate of SOD activity in leaves and roots of plant species. Results show the crop A. hypogaea is highly sensitive even at very low cadmium concentrations.

关键词： toxicological effects cadmium protein proline antioxidant enzymes

Microstructure and brazing mechanism of porous Si_3N_4/Invar joint brazed with Ag-Cu-ti/Cu/Ag-Cu multi-layered filler

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Journal of Materials Science & technology 2018年第4期34卷 713-719页

作者： J.Zhang J.y.Liu t.P.Wang School of Materials Science and Engineering Harbin Institute of Technology

Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2ti and Ni3ti intermetallic compounds. the effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. the typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/tiN ＋ ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer ＋ diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength （73 MPa） was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-ti brazing alloy and had reached 86% of the ceramic. the release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2ti and Ni3ti intermetallics played the major role in the improvement of joint strength.

关键词： Porous Si3N4 Invar alloy Brazing Microstructure Mechanical properties

Natural vibration of cantilever porous twisted plate with variable thickness in different directions

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Defence technology（防务技术） 2023年第9期27卷 200-216页

作者： y.X.Hao y.y.Liu W.Zhang L.t.Liu K.C.Sun S.W.yang College of Mechanical Engineering Beijing Information Science and Technology UniversityBeijing100192PR China College of Mechanical Engineering Beijing University of TechnologyBeijing100124PR China

In this paper,the blade is assumed to be a rotating variable thickness cantilever twisted plate structure,and the natural vibrations of variable thickness cantilever twisted plate made of metal porous material are *** is assumed that the thickness of the plate changes along spanwise direction and chordwise direction,respectively,and it changes in both *** classical thin shell theory,the first and second fundamental forms of surface and von Karman geometric relationship are employed to derive the total potential energy and kinetic energy of the cantilever twisted plate,in which the centrifugal force potential due to high rotational speed is ***,according to the Rayleigh-Ritz procedure and applying the polynomial functions which satisfy the cantilever boundary conditions,the dynamic system expressed by equations of motion is reduced to an eigenvalue *** numerical simulation,the frequency curves and the mode shapes of the twisted plate can be obtained to reveal the internal connection between natural vibration and the parameters.A series of comparison studies are performed to verify the accuracy of the present formulation and calculations,in which compared data come from experimental,finite element method and theoretical calculation,*** influence of pre-twist angle,three different forms of thickness taper ratio and rotational speed on natural vibration,mode exchange and frequency veering phenomenon of the system is discussed in *** addition,the approach proposed here can efficiently extract analytical expressions of mode functions for rotating variable thickness cantilever twisted plate structures.

关键词： Porous cantilever twisted plate Variable thickness Natural vibration Frequency veering Mode exchange

First principles calculations on the thermoelectric properties of bulk Au2S with ultra-low lattice thermal conductivity

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Chinese Physics B 2020年第8期29卷 108-114页

作者： y y Wu X L Zhu H y yang Z G Wang y H Li B t Wang School of Nuclear Science and technology Lanzhou UniversityLanzhou 730000China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523808China School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Sulfide nanocrystals and their composites have shown great potential in the thermoelectric(tE)field due to their extremely low thermal *** a solid and hollow metastable Au2S nanocrystalline has been successfully ***,we study the tE properties of this bulk Au2S by first-principles calculations and semiclassical Boltzmann transport theory,which provides the basis for its further experimental *** results indicate that the highly twofold degeneracy of the bands appears at theΓpoint in the Brillouin zone,resulting in a high Seebeck ***,Au2S exhibits an ultra-low lattice thermal conductivity(~0.88 W·m^-1·K^-1 at 700 K).At 700 K,the thermoelectric figure of merit of the optimal p-type doping is close to 1.76,which is higher than 0.8 of ZrSb at 700 K and 1.4 of Ptte at 750 *** work clearly demonstrates the advantages of Au2S as a tE material and would greatly inspire further experimental studies and verifications.

关键词： first principles calculation thermodynamic transport properties

Enhancing strength and ductility of AlSi10Mg fabricated by selective laser melting by tiB_(2)nanoparticles

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Journal of Materials Science & technology 2022年第14期109卷 254-266页

作者： y.K.Xiao H.Chen Z.y.Bian t.t.Sun H.Ding Q.yang y.Wu Q.Lian Z.Chen H.W.Wang State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In the metallic components fabricated by the emerging selective laser melting(SLM)technology,most strategies used for strengthening the materials sacrifice the ductility,leading to the so-called strengthductility *** the present study,we report that the strength and ductility of materials can be enhanced simultaneously by introducing nanoparticles,which can break the trade-off of the metallic *** the case of in-situ nano-tiB_(2)decorated AlSi10Mg composites,the introduced nanoparticles lead to columnar-to-equiaxed transition,grain refinement and texture *** increasing content of nanoparticles,the strength increases ***,the ductility first increases and then *** results show that the ductility is controlled by the competition between the crack-induced catastrophic fracture and ductile fracture associated with dislocation *** first increase of ductility is mainly attributed to the suppression of crack-induced catastrophic fracture when tiB_(2)nanoparticles *** the further increase of tiB_(2)nanoparticles,the subsequent decrease of ductility is mainly controlled by dislocation ***,the materials will exhibit the optimum strength and ductility combination in a certain range of tiB_(2)*** study clarifies the physical mechanism controlling ductility for nano-tiB_(2)decorated Al Si10Mg composites,which provides the insights for the design of structural materials.

关键词： Selective laser melting Aluminium matrix composites Ductility Mechanical behavior Dislocations Cracks

Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2198-2218页

作者： Mengqi Wang y.t.Feng Shaoheng Guan tongming Qu Zienkiewicz Centre for Computational Engineering Faculty of Science and EngineeringSwansea UniversitySwanseaWalesSA18EPUK Institute of theoretical and Computational Physics Graz University of TechnologyGraz8010Austria Department of Civil and Environmental Engineering Hong Kong University of Science and TechnologyClearwater BayKowloonHong KongChina

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading *** this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular *** obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing *** obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved *** results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials.

关键词： Granular materials History-dependence Multi-layer perceptron(MLP) Discrete element method FEM-DEM Machine learning

Measurements on diproton emission from the break-up channels of ^(23)Al and ^(22)Mg

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Science China(Physics,Mechanics & Astronomy) 2011年第S1期54卷 18-23页

作者： tOGANO y AOI N BABA H HONDA t OKADA K HARA y IEKI K ISHIBASHI y ItOU y IWASA N KANNO S KAWABAtA t KIMURA H KONDO y KURItA K KUROKAWA M MORIGUCHI t MURAKAMI H OISHI H OtA S OZAWA A SAKURAI H SHIMOURA S SHIODA R tAKESHItA E tAKEUCHI S yAMADA K yAMADA y yASUDA y yONEDA K MOtOBAyASHI t Institute of Physical and Chemical Research (RIKEN) Wako Saitama 351-0198 Japan Department of Physics Rikkyo University Japan Institute of Physics University of Tsukuba Ibaraki Japan Department of Physics Tohoku University Japan Center for Nuclear Study (CNS) University of Tokyo Japan Department of Physics University of Tokyo Japan

two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. the results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg.

关键词： diproton emission proton-rich nuclei 23Al and 22Mg

Microstructural Evolution of Infrared Brazed CP-ti Using ti-Cu-Ni Brazes

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Journal of Materials Science & technology 2011年第2期27卷 131-138页

作者： C.t.Chang t.y.yeh R.K.Shiue C.S.Chang Department of Mechanical Engineering National Hualien Industrial Vocational Senior High SchoolHualien 970TaiwanChina Department of Materials Science and Engineering National Taiwan UniversityTaipei 106TaiwanChina Engineered Materials Solutions 39 Perry AvenueMS 4-1AttleboroMA 02703-2410USA

Microstructural evolution of infrared vacuum brazed CP-ti using two ti-based braze alloys,ti-15Cu-15Ni and ti-15Cu-25Ni,has been *** infrared brazed joint consisted of eutectic ti 2 Cu/ti 2 Ni intermetallic compounds and ti-rich *** eutectic ti 2 Cu/ti 2 Ni intermetallic compounds disappeared from the joint after being annealed at 900 C for 1 *** contrast,the depletion rate of both Cu and Ni from the braze alloy into CP-ti substrate at 750 C annealing was greatly decreased as compared with that annealed at 900 *** ti 2 Cu/ti 2 Ni phases were observed even if the specimen was annealed at 750 C for 15 *** the Ni content of the ti-15Cu-25Ni braze alloy is much higher than that of the ti-15Cu-15Ni alloy,the amount of eutectic ti 2 Cu/ti 2 Ni phases in ti-15Cu-25Ni brazed joint is more than that in ti-15Ci-15Ni brazed ***,similar microstructural evolution can be obtained from the infrared brazed joint annealed at various temperatures and/or time for both filler metals.

关键词： Infrared Brazing CP-ti ti-Cu-Ni fillers Microstructure