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Impact of coupling geometry on thermoelectric properties of oligophenyl-base transistor

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Chinese Physics B 2017年第2期26卷 420-427页

作者： S Ramezani Akbarabadi H Rahimpour Soleimanit m Bagheri Tagani z Golsanamlou Computational Nanophysics Laboratory （CNL） Department of Physics University of Guilan Rasbt P. O. Box 41335-1914Iran

Thermal and electron transport through organic molecules attached to three-dimensional gold electrodes in two different configurations, namely para and meta with thiol-terminated junctions is studied theoretically in the linear response regime using Green＇s function formalism. We used thiol-terminated（–SH bond） benzene units and found a positive thermopower because the highest occupied molecular orbital（HOmO） is near the Fermi energy level. We investigated the influence of molecular length and molecular junction geometry on the thermoelectric properties. Our results show that the thermoelectric properties are highly sensitive to the coupling geometry and the molecular length. In addition, we observed that the interference effects and increasing molecular length can increase the thermoelectric efficiency of device in a specific configuration.

关键词： coupling geometry figure of merit Green's function oligophenyl thermopower

Formation of TiAlSi intermetallics during heating Ti-A356 Al mixed powder compact at semisolid temperature

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Journal of materials Science & Technology 2021年第35期94卷 247-263页

作者： m.Gao T.J.Chen z.X.zhang State Key Laboratory of Advanced Processing and Recycling of Nonferrous metals Lanzhou University of TechnologyLanzhou 730050China

Due to the similarity in composition and crystal structure of some Ti Al Si ternary intermetallics,it is quite difficult to accurately confirm their physic characteristics,and thus,to tailor microstructure to improve mechanical properties of metal materials related to the Ti Al Si ***,the formation process of Ti Al Si intermetallics was investigated during heating Ti-A356 mixed powder compact at a A356 alloy semisolid temperature of 595℃.The results indicated that two kinds of intermetallics ofτ1(tetragonal,I41/amd)andτ2(orthorhombic,Cmcm)generated,and both the concentration and supply direction of Ti atoms,which are related to local breakage of oxide films on neighboring Ti and A356 alloy powders,determined the phase and morphology of the intermetallics.τ1 andτ2 crystals all had an intrinsic plate morphology,butτ2 crystals were thinner due to more anisotropic growth resulted from their high density of stacking faults(SFs).τ1 lamellar domains generated during growth ofτ2 crystals,which were accompanied by decrease in density of *** combined effect of size difference and internal energy difference betweenτ1 andτ2 crystals made largeτ1 crystals coarsen at the expense ofτ2 crystals in Ostwald ripening,leading them to finally evolve into an agglomerate of largeτ1 plates.

关键词： Intermetallics Stacking faults Growth Phase transformation

Brownian motion and thermophoresis effects on unsteady stagnation point flow of Eyring-Powell nanofluid: a Galerkin approach

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Communications in Theoretical Physics 2020年第12期72卷 71-82页

作者： z H Khan m Usman T zubair m Hamid R U Haq State Key Laboratory of Hydraulics and mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China BIC-ESAT College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering SciencePeking UniversityBeijing 100871China Institute of Ocean Research Peking UniversityBeijing 100871China School of mathematical Sciences Peking UniversityBeijing 100871China Department of mechanics and Engineering Science Fudan UniversityShanghai 200433China Department of Electrical Engineering Bahria UniversityIslamabad CampusIslamabad 44000Pakistan

This article concerns the analysis of an unsteady stagnation point flow of Eyring–Powell nanofluid over a stretching *** influence of thermophoresis and Brownian motion is also considered in transport *** nonlinear ODE set is obtained from the governing nonlinear equations via suitable *** numerical experiments are performed using the Galerkin scheme.A tabular form comparison analysis of outcomes attained via the Galerkin approach and numerical scheme(RK-4)is available to show the credibility of the Galerkin *** numerical exploration is carried out for various governing parameters,namely,Brownian motion,steadiness,thermophoresis,stretching ratio,velocity slip,concentration slip,thermal slip,and fluid parameters,and Hartmann,Prandtl and Schmidt *** velocity of fluid enhances with an increase in fluid and magnetic parameters for the case of opposing,but the behavior is reversed for assisting *** Brownian motion and thermophoresis parameters cause an increase in temperature for both cases(assisting and opposing).The Brownian motion parameter provides a drop-in concentration while an increase is noticed for the thermophoresis *** the outcomes and the behavior of emerging parameters are illustrated *** comparison analysis and graphical plots endorse the appropriateness of the Galerkin *** is concluded that said method could be extended to other problems of a complex nature.

关键词： Eyring-Powell fluid stagnation point flow Brownian motion and thermophoresis Galerkin method

Synergetic deformation mechanisms in an mg-zn-Y-zr alloy with intragranular LPSO structures

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Journal of magnesium and Alloys 2023年第5期11卷 1754-1768页

作者： z.z.Peng X.H.Shao z.m.Liang D.L.Wang L.W.Wang X.L.ma Hebei Key Laboratory of material Near-Net Forming Technology School of Materials Science and EngineeringHebei University of Science and TechnologyShijiazhuang 050018China Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences72 Whenua RoadShenyang 110016China

Deformation kink is one of the important strengthening mechanisms of the long-period-stacking-ordered(LPSO)phase containing magnesium(mg)alloys,while the deformation twin is generally *** optimize the mechanical properties of LPSO containing mg alloy by simultaneously exciting kink and twin,we successfully prepared the mg-zn-Y-zr alloy featuring intragranular LPSO phase and free grain boundary LPSO phase by *** unraveled the corresponding strengthening and toughening mechanisms through transmission electron microscopy characterization and theoretical *** high strength and good plasticity of the homogenized alloy benefit from the synergistic deformation mechanism of multiple kinking and twining in the *** the activation of kinking and twinning depends on the thicknesses of LPSO lamellae and their relative *** results may shed light on optimizing the design of mg alloys regulating the microstructure of LPSO phases.

关键词： mg alloy LPSO distribution Kink Twin Transmission electron microscopy

Effect of Rotation Rate on microstructures and mechanical Properties of FSW mg-zn-Y-zr Alloy Joints

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Journal of materials Science & Technology 2011年第12期27卷 1157-1164页

作者： G.m. Xie z.Y. ma z.A. Luo P. Xue G.D. Wang The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 China Shenyang National Laboratory for materials Science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

Friction stir welding （FSW） of mg-zn-Y-zr plates with 6 mm in thickness was successfully carried out under a wide range of rotation rates of 600-1200 r/rain with a constant traverse speed of 100 mm/min. After FSW, the coarse grains in the parent material （Pm） were changed into fine equiaxed recrystallized grains at the＇nugget zone （Nz）. Furthermore, the coarse mg-zn-Y particles （W-phase） were broken up and dispersed homogenously into the mg matrix. With increasing rotation rates, the size of the W-phase particles at the Nz significantly decreased, but the recrystallized grain size tended to increase. The hardness values of the Nzs for all the FSW joints were higher than those of the Pm, and the lowest hardness values were detected in the heat affected zone （HAz）. The fracture occurred in the thermo-mechanical affected zone （TmAz） on the advancing side for all the FSW joints in the tensile test, due to the incompatibility of the plastic deformation between the Nz and TmAz caused by remarkably different orientation of grains and W-phase particles. The strength of FEW ioint reaches 90% of that of its Pm

关键词： Friction stir welding magnesium alloys microstructure mechanical property

Simulation of the spatio-temporal evolution of the electron energy distribution function in a pulsed hollow-cathode discharge

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Plasma Science and Technology 2023年第3期25卷 87-94页

作者： N A ASHURBEKOV K O ImINOV K m RABADANOV G S SHAKHSINOV m z zAKARYAEVA m B KURBANGADzHIEVA Dagestan State University Department of Physics Harbin Institute of Technology Institute of Physics Dagestan Federal Research CenterRussian Academy of Sciences

This article presents the 2D simulation results of a nanosecond pulsed hollow cathode discharge obtained through a combination of fluid and kinetic *** spatio-temporal evolution of the electron energy distribution function(EEDF)of the plasma column and electrical characteristics of the nanosecond pulsed hollow cathode discharge at a gas pressure of 5 Torr are *** results show that the discharge development starts with the formation of an ionization front at the anode *** ionization front splits into two parts in the cathode cavity while propagating along its lateral *** ionization front formation leads to an increase in the fast isotropic EEDF component at its front,as well as in the anisotropic EEDF *** accelerated electrons enter the cathode cavity,which significantly contributes to the formation of the highenergy EEDF component and EEDF anisotropy.

关键词： pulsed nanosecond discharge electron energy distribution fuinction hollow cathode electron kinetics gas discharge

Optical and magnetic properties of perovskite materials:Ba_(0.3)La_(0.7)Ti_(0.3)Fe_(0.7)O_(3) and Ba_(0.1)La_(0.9)Ti_(0.1)Fe_(0.9)O_(3)

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Journal of Rare Earths 2022年第4期40卷 652-659,I0005页

作者： Fatima El Bachraoui zakaria Chchiyai youssef Tamraoui Hassan El moussaoui Jones Alami Bouchaib manoun materials Science Energy and Nano-engineering Department(MSN)University Mohammed VI Polytechnic43150BenguerirMorocco Hassan First University of Settat FSTRayonnement-Matière et InstrumentationS3M26000SettatMorocco materials and Nanomaterials Center Moroccan Foundation for Advanced ScienceInnovation and Research10100RabatMorocco

Structural,optical and magnetic properties are reported for new synthesized perovskite ***_(0.3)La_(0.7)Ti_(0.3)Fe_(0.7)O_(3) and Ba_(0.1)La_(0.9)Ti_(0.1)Fe_(0.9)O_(3) compositions were prepared via solid state reaction.X-ray analysis confirms that both compositions show feature of perovskite *** refinement method was used to confirm the phase formation and investigate the structure and space *** study demonstrates the formation of orthorhombic structure with Pnma space group for Ba_(0.3)La_(0.7)Ti_(0.3)Fe_(0.7)O_(3) while the composition Ba_(0.1)La_(0.9)Ti_(0.1)Fe_(0.9)O_(3) structure adopts Pbnm ***–vis spectroscopy measurements show very broad and intense UV–visible light absorption,the estimated band gap ranges between 2.07 and 2.15 *** measurements were carried out for the compositions Ba_(0.3)La_(0.7)Ti_(0.3)Fe_(0.7)O_(3) and Ba_(0.1)La_(0.9)Ti_(0.1)Fe_(0.9)O_(3).The hysteresis loops of both samples at 300 and 10 K show a strong ferromagnetic *** temperature dependent magnetization at 0.05 T under field-cooled(FC)and zero field cooled(zFC)modes shows magnetic frustration or spin glass-like behavior.

关键词： Perovskites Co-substitution effect Phase transition Band gap Ferromagnetic Visible light absorption

Coherence of SH-waves near a semi-circular inclusion-the role of interference and standing waves

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 535-552页

作者： z.Tokmechi R.S.Jalali m.D.Trifunac m.I.Todorovska Department of Civil Engineering Faculty of EngineeringUniversity of GuilanP.O.Box 3756RashtIran Department of Civil Engineering University of Southern CaliforniaLos AngelesCalifornia 90089USA Department of Civil Engineering Tianjin UniversityTianjin 300350China

We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground *** show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering *** examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the *** show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is *** also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by *** examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.

关键词： coherence of strong motion coherence in the presence of standing waves coherence caused by interference reduction of coherence for radiation from large faults

The η-Pairing Superconductivity in Spin-Density Wave Background

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Chinese Physics Letters 1993年第10期10卷 616-619页

作者： X.m.Qiu z.J.Wang Southwestern Institute of Physics P.O.Box 432Chengdu 610041

In this letter,we propose a modified attractive Hubbard model at half filling that can exhibit sup er con ductivity through η-pairing *** in spin-density wave representation and derive a concise relationship between the energy disparity and the single-particle energy *** relationship,in the two limits of U,clearly shows that the system does not display sup er con ductivity for very low doping concen・*** *** s up ere on ductivity when the doping concentration exceeds a certain critical *** conclusion is in quaJitative agreement with the familiar experiments on higli-T_(c) supcrconductivity.

关键词： spectrum value doping