The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, i...The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, ion beam implantation technique has been extensively applied to many biological fields. This paper mainly introduces one of its important applications: genetic transformation mediated by keV ion beam.展开更多
Laser transformation hardening(LTH) is one of the laser surface modification processes.The surface hardening of rod-shaped carbon steel(SM45C) was performed by lathe-based laser composite processor with Gaussian-beam ...Laser transformation hardening(LTH) is one of the laser surface modification processes.The surface hardening of rod-shaped carbon steel(SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head.The LTH characteristics by dominant processes,longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined.Especially,two concepts of circumferential speed and theoretical overlap rate were applied.When laser power increased or circumferential speed decreased,the surface hardening depth gradually increases due to the increased heat input.Moreover,the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease,which results from tempering effect by overlap.Finally,the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution.展开更多
This paper illustrates the crack identification method combining wavelet analysis with transform matrix. Firstly, the fundamental vibration mode was applied to wavelet analysis. The crack location was found by the pea...This paper illustrates the crack identification method combining wavelet analysis with transform matrix. Firstly, the fundamental vibration mode was applied to wavelet analysis. The crack location was found by the peaks of the wavelet coefficients. Secondly, based on the identified crack locations, a simple transform matrix method requiring only the first two tested natural frequencies was used to further identify the crack depth. The present method can be used for crack identification in a complex structure. Numerical results of crack identification of a stepped cantilever beam show that the suggested method is feasible.展开更多
The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The...The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.展开更多
In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transfo...In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transformer with In-flange was fabricated.Theoretical analysis,numerical simulations and experimental results are given.展开更多
This paper introduces Lorentz beams to describe certain laser sources that produce highly divergent fields.The fractional Fourier transform （FRFT） is applied to treat the propagation of Lorentz beams.Based on the de...This paper introduces Lorentz beams to describe certain laser sources that produce highly divergent fields.The fractional Fourier transform （FRFT） is applied to treat the propagation of Lorentz beams.Based on the definition of convolution and the convolution theorem of the Fourier transform,an analytical expression for a Lorentz beam passing through a FRFT system has been derived.By using the derived formula,the properties of a Lorentz beam in the FRFT plane are illustrated numerically.展开更多
The generalized integral transform technique （GITT） is used to find a semianalytical numerical solution for dynamic response of an axially moving Timoshenko beam with clamped-clamped and simply-supported boundary co...The generalized integral transform technique （GITT） is used to find a semianalytical numerical solution for dynamic response of an axially moving Timoshenko beam with clamped-clamped and simply-supported boundary conditions, respectively. The implementation of GITT approach for analyzing the forced vibration equation eliminates the space variable and leads to systems of second-order ordinary differential equations （ODEs） in time. The MATHEMATICA built-in function, NDSolve, is used to numerically solve the resulting transformed ODE system. The good convergence behavior of the suggested eigenfunction expansions is demonstrated for calculating the transverse deflection and the angle of rotation of the beam cross-section. Moreover, parametric studies are performed to analyze the effects of the axially moving speed, the axial tension, and the amplitude of external distributed force on the vibration amplitude of axially moving Timoshenko beams.展开更多
Based on the nonlocal nonlinear Schr6dinger equation, the propagation properties of anomalous hollow beams in strongly isotropic nonlocal media are investigated. The analytical expressions of the beam propagation, the...Based on the nonlocal nonlinear Schr6dinger equation, the propagation properties of anomalous hollow beams in strongly isotropic nonlocal media are investigated. The analytical expressions of the beam propagation, the on-axis intensity and the beam width are obt.ained. The results show that the evolution of the beam is periodical and the input power is the most important parameter. The input power determines the variation of the period. Furthermore, it is found that there exists a critical input power in the x direction and in the y direction separately when the initial beam widths in the two transversal directions are unequal. The beam width remains invariant in the corresponding transversal direction when the input power equals the critical power in one of the transversal directions. Selecting a properinput power, the beam can be broadened or compressed in the two transversal directions at the same time, In particular, the beam can be broadened （compressed） in one transversal direction, whereas in the other transversal direction, it is compressed （broadened）, i.e., the transversal reverse transformation.展开更多
The No.601 watermelon (citrullus lanatus) seeds were treated with 25 keV N+ implantation at the dosage of 7.8 ×1016 ions/cm2. After treatment, watermelon seeds were incubated with 380μg/μl pumpkin (Cucubita, ma...The No.601 watermelon (citrullus lanatus) seeds were treated with 25 keV N+ implantation at the dosage of 7.8 ×1016 ions/cm2. After treatment, watermelon seeds were incubated with 380μg/μl pumpkin (Cucubita, maxima Duch) DNA solution at 35 ℃ for 5 hours. By two-generations of selection and resistance screening at seedling stage, one transformed material was selected out, whose rind color is similar to that of the donor pumpkin and whose size of seeds is between that of the donor and the receptor. Using AFLP (amplified fragment length polymorphism) technique, two polymorphic DNA fragments were amplified. This primarily testified that the donor DNA fragments/gene were introduced into the receptor cell and integrated into the genomic DNA of the receptor.展开更多
The interferogram of multiple-beam Fizeau fringe technique plays an important role to investigate the optical properties of fiber because this interferogram provides us with useful information which can used to determ...The interferogram of multiple-beam Fizeau fringe technique plays an important role to investigate the optical properties of fiber because this interferogram provides us with useful information which can used to determine the dispersion curve of the fiber sample. A common problem in any interferogram analysis is the accuracy in locating fringe centers (fringe skeleton). There are a lot of computer-aided algorithms, which depend on the interferogram types, used to fringe skeleton extraction of various digital interferogram. In this paper, as far as I know, a novel algorithm for fringe skeleton extraction of double bright fringe of multiple-beam Fizeau fringe is presented. The proposed algorithm based on using the different order of Fourier transform and the derivative-sign binary image. Also the proposed algorithm has been successfully tested by using a computer simulation fringe and an experimental pattern. The results are compared with the original interferogram and shown a good agreement.展开更多
A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hy...A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEM (Finite Element Method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.展开更多
The dynamic continuous cooling transformation（CCT）diagram and phase transformation rules of 510 MPa automobile beam steel,which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron an...The dynamic continuous cooling transformation（CCT）diagram and phase transformation rules of 510 MPa automobile beam steel,which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron and Steel Co.Ltd.,are researched by thermal simulation experiment.The microstructure characteristics of the beam steel under different test conditions are studied by means of optical microscope and scanning electron microscope.The test results show that the critical temperatures of phase transformation Ar3 and Ar1 will all decrease with the increase of the cooling rate.When the cooling rate is lower than 20 ℃·s-1,the ferrite and pearlite phase transformations are the main parts;when the cooling rate is higher than 20 ℃·s-1,the bainite phase appears.Moreover,the microstructures of 510 MPa automobile beam steel produced by FTSR technology are also studied,and the results are basically in accordance with the CCT diagram gained from the test.展开更多
Based on the principle of linear superposition, this paper proves generalized Duhamel's integral which reserves moving dynamical load problem to fixed dynamical load problem. Laplace transform and Fourier transfor...Based on the principle of linear superposition, this paper proves generalized Duhamel's integral which reserves moving dynamical load problem to fixed dynamical load problem. Laplace transform and Fourier transform are used to solve patial differential equation of infinite beam. The generalized Duhamel's integral and deflection impulse response function of the beam make it easy for us to obtain final solution of moving line load problem. Deep analyses indicate that the extreme value of dynamic response always lies in the center of the line load and travels with moving load at the same speed. Additionally, the authors also present definition of moving dynamic coefficient which reflects moving effect.展开更多
The dynamic response of an infinite Euler–Bernoulli beam resting on Pasternak foundation under inclined harmonic line loads is developed in this study in a closed-form solution.The conventional Pasternak foundation i...The dynamic response of an infinite Euler–Bernoulli beam resting on Pasternak foundation under inclined harmonic line loads is developed in this study in a closed-form solution.The conventional Pasternak foundation is modeled by two parameters wherein the second parameter can account for the actual shearing effect of soils in the vertical direction.Thus,it is more realistic than the Winkler model,which only represents compressive soil resistance.However,the Pasternak model does not consider the tangential interaction between the bottom of the beam and the foundation;hence,the beam under inclined loads cannot be considered in the model.In this study,a series of horizontal springs is diverted to the face between the bottom of the beam and the foundation to address the limitation of the Pasternak model,which tends to disregard the tangential interaction between the beam and the foundation.The horizontal spring reaction is assumed to be proportional to the relative tangential displacement.The governing equation can be deduced by theory of elasticity and Newton’s laws,combined with the linearly elastic constitutive relation and the geometric equation of the beam body under small deformation condition.Double Fourier transformation is used to simplify the geometric equation into an algebraic equation,thereby conveniently obtaining the analytical solution in the frequency domain for the dynamic response of the beam.Double Fourier inverse transform and residue theorem are also adopted to derive the closed-form solution.The proposed solution is verified by comparing the degraded solution with the known results and comparing the analytical results with numerical results using ANSYS.Numerical computations of distinct cases are provided to investigate the effects of the angle of incidence and shear stiffness on the dynamic response of the beam.Results are realistic and can be used as reference for future engineering designs.展开更多
文摘The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, ion beam implantation technique has been extensively applied to many biological fields. This paper mainly introduces one of its important applications: genetic transformation mediated by keV ion beam.
文摘Laser transformation hardening(LTH) is one of the laser surface modification processes.The surface hardening of rod-shaped carbon steel(SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head.The LTH characteristics by dominant processes,longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined.Especially,two concepts of circumferential speed and theoretical overlap rate were applied.When laser power increased or circumferential speed decreased,the surface hardening depth gradually increases due to the increased heat input.Moreover,the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease,which results from tempering effect by overlap.Finally,the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution.
基金supported by the Key Natural Science Research of Guangdong Province,China P.R(Grant No.05Z003)the Project of Tackling Key Problem of Guangdong Province,China P.R(Grant No.2006B12401008)the National Natural Science Foundation of China(Grant No.10672067).
文摘This paper illustrates the crack identification method combining wavelet analysis with transform matrix. Firstly, the fundamental vibration mode was applied to wavelet analysis. The crack location was found by the peaks of the wavelet coefficients. Secondly, based on the identified crack locations, a simple transform matrix method requiring only the first two tested natural frequencies was used to further identify the crack depth. The present method can be used for crack identification in a complex structure. Numerical results of crack identification of a stepped cantilever beam show that the suggested method is feasible.
文摘The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.
文摘In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transformer with In-flange was fabricated.Theoretical analysis,numerical simulations and experimental results are given.
基金Project supported by the Scientific Research Fund of Zhejiang Provincial Education Department of China
文摘This paper introduces Lorentz beams to describe certain laser sources that produce highly divergent fields.The fractional Fourier transform （FRFT） is applied to treat the propagation of Lorentz beams.Based on the definition of convolution and the convolution theorem of the Fourier transform,an analytical expression for a Lorentz beam passing through a FRFT system has been derived.By using the derived formula,the properties of a Lorentz beam in the FRFT plane are illustrated numerically.
基金Project supported by the Science Foundation of China University of Petroleum in Beijing(No.2462013YJRC003)
文摘The generalized integral transform technique （GITT） is used to find a semianalytical numerical solution for dynamic response of an axially moving Timoshenko beam with clamped-clamped and simply-supported boundary conditions, respectively. The implementation of GITT approach for analyzing the forced vibration equation eliminates the space variable and leads to systems of second-order ordinary differential equations （ODEs） in time. The MATHEMATICA built-in function, NDSolve, is used to numerically solve the resulting transformed ODE system. The good convergence behavior of the suggested eigenfunction expansions is demonstrated for calculating the transverse deflection and the angle of rotation of the beam cross-section. Moreover, parametric studies are performed to analyze the effects of the axially moving speed, the axial tension, and the amplitude of external distributed force on the vibration amplitude of axially moving Timoshenko beams.
基金supported by the National Natural Science Foundation of China(Grant Nos.61308016,11374089,and 11347121)the Natural Science Foundationof Hebei Province,China(Grant Nos.A2012205023,F2012205076,and A2012205085)+3 种基金the Natural Science Foundation of Hunan Province,China(GrantNo.13JJ4097)the China Postdoctoral Science Foundation(Grant No.2014M551041)the Research Foundation of Education Bureau of Hebei Province,China(Grant No.ZD20131014)Hebei Normal University Foundation,China(Grant No.L2011B06)
文摘Based on the nonlocal nonlinear Schr6dinger equation, the propagation properties of anomalous hollow beams in strongly isotropic nonlocal media are investigated. The analytical expressions of the beam propagation, the on-axis intensity and the beam width are obt.ained. The results show that the evolution of the beam is periodical and the input power is the most important parameter. The input power determines the variation of the period. Furthermore, it is found that there exists a critical input power in the x direction and in the y direction separately when the initial beam widths in the two transversal directions are unequal. The beam width remains invariant in the corresponding transversal direction when the input power equals the critical power in one of the transversal directions. Selecting a properinput power, the beam can be broadened or compressed in the two transversal directions at the same time, In particular, the beam can be broadened （compressed） in one transversal direction, whereas in the other transversal direction, it is compressed （broadened）, i.e., the transversal reverse transformation.
基金This work was supported by National Key Project (96-538-01-01).
文摘The No.601 watermelon (citrullus lanatus) seeds were treated with 25 keV N+ implantation at the dosage of 7.8 ×1016 ions/cm2. After treatment, watermelon seeds were incubated with 380μg/μl pumpkin (Cucubita, maxima Duch) DNA solution at 35 ℃ for 5 hours. By two-generations of selection and resistance screening at seedling stage, one transformed material was selected out, whose rind color is similar to that of the donor pumpkin and whose size of seeds is between that of the donor and the receptor. Using AFLP (amplified fragment length polymorphism) technique, two polymorphic DNA fragments were amplified. This primarily testified that the donor DNA fragments/gene were introduced into the receptor cell and integrated into the genomic DNA of the receptor.
文摘The interferogram of multiple-beam Fizeau fringe technique plays an important role to investigate the optical properties of fiber because this interferogram provides us with useful information which can used to determine the dispersion curve of the fiber sample. A common problem in any interferogram analysis is the accuracy in locating fringe centers (fringe skeleton). There are a lot of computer-aided algorithms, which depend on the interferogram types, used to fringe skeleton extraction of various digital interferogram. In this paper, as far as I know, a novel algorithm for fringe skeleton extraction of double bright fringe of multiple-beam Fizeau fringe is presented. The proposed algorithm based on using the different order of Fourier transform and the derivative-sign binary image. Also the proposed algorithm has been successfully tested by using a computer simulation fringe and an experimental pattern. The results are compared with the original interferogram and shown a good agreement.
文摘A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEM (Finite Element Method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.
基金Item Sponsored by National Natural Science Foundation of China(50334010)FOK YING TUNG Education Foundation(104017)
文摘The dynamic continuous cooling transformation（CCT）diagram and phase transformation rules of 510 MPa automobile beam steel,which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron and Steel Co.Ltd.,are researched by thermal simulation experiment.The microstructure characteristics of the beam steel under different test conditions are studied by means of optical microscope and scanning electron microscope.The test results show that the critical temperatures of phase transformation Ar3 and Ar1 will all decrease with the increase of the cooling rate.When the cooling rate is lower than 20 ℃·s-1,the ferrite and pearlite phase transformations are the main parts;when the cooling rate is higher than 20 ℃·s-1,the bainite phase appears.Moreover,the microstructures of 510 MPa automobile beam steel produced by FTSR technology are also studied,and the results are basically in accordance with the CCT diagram gained from the test.
文摘Based on the principle of linear superposition, this paper proves generalized Duhamel's integral which reserves moving dynamical load problem to fixed dynamical load problem. Laplace transform and Fourier transform are used to solve patial differential equation of infinite beam. The generalized Duhamel's integral and deflection impulse response function of the beam make it easy for us to obtain final solution of moving line load problem. Deep analyses indicate that the extreme value of dynamic response always lies in the center of the line load and travels with moving load at the same speed. Additionally, the authors also present definition of moving dynamic coefficient which reflects moving effect.
基金financially supported by the National Key Research and Development Program of China (no.2016YFC0800206)the National Natural Science Foundation of China (nos.51778260, 51378234, 51678465)
文摘The dynamic response of an infinite Euler–Bernoulli beam resting on Pasternak foundation under inclined harmonic line loads is developed in this study in a closed-form solution.The conventional Pasternak foundation is modeled by two parameters wherein the second parameter can account for the actual shearing effect of soils in the vertical direction.Thus,it is more realistic than the Winkler model,which only represents compressive soil resistance.However,the Pasternak model does not consider the tangential interaction between the bottom of the beam and the foundation;hence,the beam under inclined loads cannot be considered in the model.In this study,a series of horizontal springs is diverted to the face between the bottom of the beam and the foundation to address the limitation of the Pasternak model,which tends to disregard the tangential interaction between the beam and the foundation.The horizontal spring reaction is assumed to be proportional to the relative tangential displacement.The governing equation can be deduced by theory of elasticity and Newton’s laws,combined with the linearly elastic constitutive relation and the geometric equation of the beam body under small deformation condition.Double Fourier transformation is used to simplify the geometric equation into an algebraic equation,thereby conveniently obtaining the analytical solution in the frequency domain for the dynamic response of the beam.Double Fourier inverse transform and residue theorem are also adopted to derive the closed-form solution.The proposed solution is verified by comparing the degraded solution with the known results and comparing the analytical results with numerical results using ANSYS.Numerical computations of distinct cases are provided to investigate the effects of the angle of incidence and shear stiffness on the dynamic response of the beam.Results are realistic and can be used as reference for future engineering designs.
