With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. In present work, 6061 aluminum alloys with different states were welded...With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. In present work, 6061 aluminum alloys with different states were welded by laser beam welding (LBW). The microstructures of welded joint, before and after heat treating, were investigated. The mechanical properties, such as the tensile properties and microhardness , were tested. And the fracture characteristic was observed by means of scanning electron microscope (SEM). The results show that the 6061 aluminum alloys have superior weldability and the microstructures are different significantly in different states. Besides, the grain boundaries of the joint microstructures become unclear after the heat treating. The strength and the elongations of welded joints could reach to those of the base metal. The tensile fracture occurs in the fusion zone and near 6061-0 alloy. And the fracture presents ductile rupture. Therefore, the LBW is an effective method for 6061 aluminum alloy.展开更多
The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination n...The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.展开更多
Inelastic electron scattering form factors has been calculated for different parity for the two (C3) transitions of 14^N for (5.83MeV) (f^π, T = 20) level and, (5.106MeV) (f^π, T = 30) level in the frame w...Inelastic electron scattering form factors has been calculated for different parity for the two (C3) transitions of 14^N for (5.83MeV) (f^π, T = 20) level and, (5.106MeV) (f^π, T = 30) level in the frame work of shell model. The model space wave functions are generated by using the Cohen-Kurath (CK) interaction, where 4He is assumed as a core and ten nucleons are distributed over the lp-shell which forms the model space. Core-polarization effects (CP) (the effects from outside lp-shell model space) are included through the first order perturbation theory. The core-polarization effects increase the form factor to be up near the experimental data which are not sufficient to give a good comparison with the calculating data.展开更多
A new synchronization scheme for chaotic(hyperchaotic) maps with different dimensions is presented.Specifically,given a drive system map with dimension n and a response system with dimension m,the proposed approach ...A new synchronization scheme for chaotic(hyperchaotic) maps with different dimensions is presented.Specifically,given a drive system map with dimension n and a response system with dimension m,the proposed approach enables each drive system state to be synchronized with a linear response combination of the response system states.The method,based on the Lyapunov stability theory and the pole placement technique,presents some useful features:(i) it enables synchronization to be achieved for both cases of n 〈 m and n 〉 m;(ii) it is rigorous,being based on theorems;(iii) it can be readily applied to any chaotic(hyperchaotic) maps defined to date.Finally,the capability of the approach is illustrated by synchronization examples between the two-dimensional H′enon map(as the drive system) and the three-dimensional hyperchaotic Wang map(as the response system),and the three-dimensional H′enon-like map(as the drive system) and the two-dimensional Lorenz discrete-time system(as the response system).展开更多
More and more educational researchers pay attention to the differences between China and the United States.Although the educational concepts of China and the United States respect"student-centered",and are v...More and more educational researchers pay attention to the differences between China and the United States.Although the educational concepts of China and the United States respect"student-centered",and are very close in educational system and institutional setting,they are still similar in curriculum design.Taking the University of Minnesota Twin Cities as an example,this paper makes a detailed comparative analysis from the four aspects of curriculum objectives,curriculum assessment,teaching activities and syllabus,finds out the essential differences between Chinese and American university curriculum design,and puts forward that the change of Chinese university curriculum design concept needs to start from basic education,and the cultivation of teachers'thinking and ability is the key influence of the reform factor.展开更多
It is well acknowledged to all that an active equalization strategy can overcome the inconsistency of lithium-ion cell's voltage and state of charge(SOC)in series-connected lithium-ion battery(LIB)pack in the elec...It is well acknowledged to all that an active equalization strategy can overcome the inconsistency of lithium-ion cell's voltage and state of charge(SOC)in series-connected lithium-ion battery(LIB)pack in the electric vehicle application.In this regard,a novel dual threshold trigger mechanism based active equalization strategy(DTTMbased AES)is proposed to overcome the inherent inconsistency of cells and to improve the equalization efficiency for a series-connected LIB pack.First,a modified dual-layer inductor equalization circuit is constructed to make it possible for the energy transfer path optimization.Next,based on the designed dual threshold trigger mechanism provoked by battery voltage and SOC,an active equalization strategy is proposed,each single cell's SOC in the battery packs is estimated using the extended Kalman particle filter algorithm.Besides,on the basis of the modified equalization circuit,the improved particle swarm optimization is adopted to optimize the energy transfer path with aiming to reduce the equalization time.Lastly,the simulation and experimental results are provided to validate the proposed DTTM-based AES.展开更多
The intensity difference squeezed state, which means that the fluctuation of the intensity difference between signal and idler beams is less than that of the corresponding shot noise level(SNL), plays an important r...The intensity difference squeezed state, which means that the fluctuation of the intensity difference between signal and idler beams is less than that of the corresponding shot noise level(SNL), plays an important role in high sensitivity measurement, quantum imaging, and quantum random numbers generation. When an optical parametric oscillator consisting of a type-Ⅱ phase-matching periodically poled KTiOPO4 crystal operates above the threshold, an intensity difference squeezed state at a telecommunication wavelength can be obtained. The squeezing of 7.7 ± 0.5 dB below the SNL is achieved in an analysis frequency region of 2.4–5.0 MHz.展开更多
文摘With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. In present work, 6061 aluminum alloys with different states were welded by laser beam welding (LBW). The microstructures of welded joint, before and after heat treating, were investigated. The mechanical properties, such as the tensile properties and microhardness , were tested. And the fracture characteristic was observed by means of scanning electron microscope (SEM). The results show that the 6061 aluminum alloys have superior weldability and the microstructures are different significantly in different states. Besides, the grain boundaries of the joint microstructures become unclear after the heat treating. The strength and the elongations of welded joints could reach to those of the base metal. The tensile fracture occurs in the fusion zone and near 6061-0 alloy. And the fracture presents ductile rupture. Therefore, the LBW is an effective method for 6061 aluminum alloy.
文摘The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.
文摘Inelastic electron scattering form factors has been calculated for different parity for the two (C3) transitions of 14^N for (5.83MeV) (f^π, T = 20) level and, (5.106MeV) (f^π, T = 30) level in the frame work of shell model. The model space wave functions are generated by using the Cohen-Kurath (CK) interaction, where 4He is assumed as a core and ten nucleons are distributed over the lp-shell which forms the model space. Core-polarization effects (CP) (the effects from outside lp-shell model space) are included through the first order perturbation theory. The core-polarization effects increase the form factor to be up near the experimental data which are not sufficient to give a good comparison with the calculating data.
文摘A new synchronization scheme for chaotic(hyperchaotic) maps with different dimensions is presented.Specifically,given a drive system map with dimension n and a response system with dimension m,the proposed approach enables each drive system state to be synchronized with a linear response combination of the response system states.The method,based on the Lyapunov stability theory and the pole placement technique,presents some useful features:(i) it enables synchronization to be achieved for both cases of n 〈 m and n 〉 m;(ii) it is rigorous,being based on theorems;(iii) it can be readily applied to any chaotic(hyperchaotic) maps defined to date.Finally,the capability of the approach is illustrated by synchronization examples between the two-dimensional H′enon map(as the drive system) and the three-dimensional hyperchaotic Wang map(as the response system),and the three-dimensional H′enon-like map(as the drive system) and the two-dimensional Lorenz discrete-time system(as the response system).
基金This paper is a key project of"student-centered"education and teaching reform and research at the university level"Research on the teaching paradigm reform of accounting"(NoZd20160401).
文摘More and more educational researchers pay attention to the differences between China and the United States.Although the educational concepts of China and the United States respect"student-centered",and are very close in educational system and institutional setting,they are still similar in curriculum design.Taking the University of Minnesota Twin Cities as an example,this paper makes a detailed comparative analysis from the four aspects of curriculum objectives,curriculum assessment,teaching activities and syllabus,finds out the essential differences between Chinese and American university curriculum design,and puts forward that the change of Chinese university curriculum design concept needs to start from basic education,and the cultivation of teachers'thinking and ability is the key influence of the reform factor.
基金supported by the Artificial intelligence technology project of Xi'an Science and Technology Bureau(No.21RGZN0014).
文摘It is well acknowledged to all that an active equalization strategy can overcome the inconsistency of lithium-ion cell's voltage and state of charge(SOC)in series-connected lithium-ion battery(LIB)pack in the electric vehicle application.In this regard,a novel dual threshold trigger mechanism based active equalization strategy(DTTMbased AES)is proposed to overcome the inherent inconsistency of cells and to improve the equalization efficiency for a series-connected LIB pack.First,a modified dual-layer inductor equalization circuit is constructed to make it possible for the energy transfer path optimization.Next,based on the designed dual threshold trigger mechanism provoked by battery voltage and SOC,an active equalization strategy is proposed,each single cell's SOC in the battery packs is estimated using the extended Kalman particle filter algorithm.Besides,on the basis of the modified equalization circuit,the improved particle swarm optimization is adopted to optimize the energy transfer path with aiming to reduce the equalization time.Lastly,the simulation and experimental results are provided to validate the proposed DTTM-based AES.
基金supported by the National Key R&D Program of China(No.2016YFA0301402)the National Natural Science Foundation of China(Nos.11474190,61601270,11654002,and 61775127)+1 种基金the Program for Sanjin Scholars of Shanxi Provincethe Fund for Shanxi "1331" Project Key Subjects Construction
文摘The intensity difference squeezed state, which means that the fluctuation of the intensity difference between signal and idler beams is less than that of the corresponding shot noise level(SNL), plays an important role in high sensitivity measurement, quantum imaging, and quantum random numbers generation. When an optical parametric oscillator consisting of a type-Ⅱ phase-matching periodically poled KTiOPO4 crystal operates above the threshold, an intensity difference squeezed state at a telecommunication wavelength can be obtained. The squeezing of 7.7 ± 0.5 dB below the SNL is achieved in an analysis frequency region of 2.4–5.0 MHz.