A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micr...A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.展开更多
Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well ...Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well wires （QWWs） are deduced and analyzed. Numerical calculations on an AIN/GaN/AIN wurtzite QWW are performed. The results reveal that the dispersions of the QC modes are quite obvious only when the free wavenumber kz in the z-direction and the azimuthal quantum number m are small. The reduced behavior of the QC modes in wurtzite quantum systems is clearly observed. Through the discussion of the electron-QC mode coupling functions,it is found that the lower-frequency QC modes in the high-frequency region play a more important role in the electron-QC phonon interactions. Moreover,our computations also prove that kz and m have a similar influence on the electron-QC phonon coupling properties.展开更多
By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived...By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived and analyzed. Numerical calculation on a freestanding wurtzite GaN quantum wire is performed. The resulte reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires, the free wave-number kz in z-direction and the dielectric constant of the nonpolar matrix. The degenerating behavior of the IO modes in Q1D wurtzite rectangular quantum wire has been clearly observed in the case of small wave-number kz and Iarge ratio of length to width of the rectangular crossing profile. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. The present theories can be looked on as a generalization of that in isotropic rectangular quantum wires, and it can naturally reduce to the case of Q1D isotropic quantum wires once the anisotropy of the wurtzite material is ignored.展开更多
Two dynamics modes, named short ablation mode and long ablation mode, are observed in implosion experiments of planar wire array Z pinch on ＇QiangGuang-I＇ facility utilizing an optical streak camera. The long ablati...Two dynamics modes, named short ablation mode and long ablation mode, are observed in implosion experiments of planar wire array Z pinch on ＇QiangGuang-I＇ facility utilizing an optical streak camera. The long ablation mode has a lagged trajectory compared with the short ablation mode. For shot 10035 in a short ablation mode, the initial time of K-shell radiation is consistent with the interaction time for ablation plasma arriving at the centre of wire array, while for shot 10038 in long ablation mode, the initial time of K-shell radiation is about 10 ns earlier. In the two modes, the partial ablation plasma could traverse the wire array plane and then collide in the centre to form a dense plasma column with a diameter of 2.2 mm for shot 10035 and 1.5 mm for shot 10038.展开更多
基金the National Natural Science Foundation of China(Nos.U21A2051,52173297,52071133)the R&D Projects of Henan Academy of Sciences of China(No.220910009)+2 种基金the Key R&D and Promotion Projects of Henan Province of China(No.212102210441)the Joint Fund of Henan Science and Technology R&D Plan of China(No.222103810037)the Zhongyuan Scholar Workstation Funded Project of China(No.214400510028).
文摘A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.
文摘Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well wires （QWWs） are deduced and analyzed. Numerical calculations on an AIN/GaN/AIN wurtzite QWW are performed. The results reveal that the dispersions of the QC modes are quite obvious only when the free wavenumber kz in the z-direction and the azimuthal quantum number m are small. The reduced behavior of the QC modes in wurtzite quantum systems is clearly observed. Through the discussion of the electron-QC mode coupling functions,it is found that the lower-frequency QC modes in the high-frequency region play a more important role in the electron-QC phonon interactions. Moreover,our computations also prove that kz and m have a similar influence on the electron-QC phonon coupling properties.
基金The project supported by the Science and Technology Project of Advanced Academy of Guangzhou City under Grant No. 2060. The author acknowledges the detailed and valuable discussions with Prof. J.J. Shi.
文摘By employing the dielectric continuum model and Loudon＇s uniaxial crystal model, the interface optical （IO） phonon modes in a freestanding quasi-one-dimensional （Q1D） wurtzite rectangular quantum wire are derived and analyzed. Numerical calculation on a freestanding wurtzite GaN quantum wire is performed. The resulte reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires, the free wave-number kz in z-direction and the dielectric constant of the nonpolar matrix. The degenerating behavior of the IO modes in Q1D wurtzite rectangular quantum wire has been clearly observed in the case of small wave-number kz and Iarge ratio of length to width of the rectangular crossing profile. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. The present theories can be looked on as a generalization of that in isotropic rectangular quantum wires, and it can naturally reduce to the case of Q1D isotropic quantum wires once the anisotropy of the wurtzite material is ignored.
文摘Two dynamics modes, named short ablation mode and long ablation mode, are observed in implosion experiments of planar wire array Z pinch on ＇QiangGuang-I＇ facility utilizing an optical streak camera. The long ablation mode has a lagged trajectory compared with the short ablation mode. For shot 10035 in a short ablation mode, the initial time of K-shell radiation is consistent with the interaction time for ablation plasma arriving at the centre of wire array, while for shot 10038 in long ablation mode, the initial time of K-shell radiation is about 10 ns earlier. In the two modes, the partial ablation plasma could traverse the wire array plane and then collide in the centre to form a dense plasma column with a diameter of 2.2 mm for shot 10035 and 1.5 mm for shot 10038.
