To study the temperature distribution and thermal-stress field in different service stages, a two-dimensional model of a turbine blade with thermal barrier coatings is developed, in which the conjugate heat transfer a...To study the temperature distribution and thermal-stress field in different service stages, a two-dimensional model of a turbine blade with thermal barrier coatings is developed, in which the conjugate heat transfer analysis and the decoupled thermal-stress calculation method are adopted. Based on the simulation results, it is found that a non-uniform distribution of temperature appears in different positions of the blade surface, which has directly impacted on stress field. The maximum temperature with a value of 1030 ℃ occurs at the leading edge. During the steady stage, the maximum stress of thermally grown oxide （TGO） appears in the middle of the suction side, reaching 3.75 GPa. At the end stage of cooling, the maximum compressive stress of TGO with a value of-3.5 GPa occurs at the leading edge. Thus, it can be predicted that during the steady stage the dangerous regions may locate at the suction side, while the leadine edge mav be more Drone to failure on cooling.展开更多
The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)conten...The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.展开更多
With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common ...With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common protective measure used in this country and abroad.The acoustic performance of a sound barrier is highly dependent on its shape and material.In this paper,a semianalytical meshless Burton-Miller‐type singular boundary method is proposed to analyze the acoustic performance of various shapes of sound barriers,and the distribution of sound‐absorbing materials on the surface of sound barriers is optimized by combining a solid isotropic material with a penalization method.The acoustic effect of the sound‐absorbing material is simplified as the acoustical impedance boundary condition.The objective of optimization is to minimize the sound pressure in a given reference plane.The volume of the sound‐absorbing material is used as a constraint.The density of the nodes covered with the sound‐absorbing material is used as the design variable.The method of moving asymptotes was used to update the design variables.This model completely avoids the mesh discretization process in the finite element method and requires only boundary nodes.In addition,the approach also does not require the singular integral calculation in the boundary element method.The method is illustrated and validated using numerical examples to demonstrate its accuracy and efficiency.展开更多
In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge,a self-designed two-dimensional axisy...In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge,a self-designed two-dimensional axisymmetric structure exciter was used to carry out optical diagnosis,with the electron temperature calculated through Gaussian fitting.A plasma model was applied to conduct research on the discharge process through numerical simulation,with the changes in electron density and electron temperature were analyzed by using different discharge parameters.The research results show that with an increase in discharge voltage,pressure inside the reactor and relative permittivity,the discharge process is promoted.In addition,a rise in current density leads to an increase in the number of charged particles on the surface of the medium during the discharge process,while a rise in discharge intensity causes an increase in the electron density.Electron temperature decreases due to the increased loss of collision energy between particles.These results were confirmed by comparing experimental data with simulation results.展开更多
Due to their many advantageous properties,nanomaterials(NMs)have been utilized in diverse consumer goods,industrial products,and for therapeutic purposes.This situation leads to a constant risk of exposure and uptake ...Due to their many advantageous properties,nanomaterials(NMs)have been utilized in diverse consumer goods,industrial products,and for therapeutic purposes.This situation leads to a constant risk of exposure and uptake by the human body,which are highly dependent on nanomaterial size.Consequently,an improved understanding of the interactions between different sizes of nanomaterials and biological systems is needed to design safer and more clinically relevant nano systems.We discuss the sizedependent effects of nanomaterials in living organisms.Upon entry into biological systems,nanomaterials can translocate biological barriers,distribute to various tissues and elicit different toxic effects on organs,based on their size and location.The association of nanomaterial size with physiological structures within organs determines the site of accumulation of nanoparticles.In general,nanomaterials smaller than 20 nm tend to accumulate in the kidney while nanomaterials between 20 and 100 nm preferentially deposit in the liver.After accumulating in organs,nanomaterials can induce inflammation,damage structural integrity and ultimately result in organ dysfunction,which helps better understand the size-dependent dynamic processes and toxicity of nanomaterials in organisms.The enhanced permeability and retention effect of nanomaterials and the utility of this phenomenon in tumor therapy are also highlighted.展开更多
Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simul...Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simulation(DES) with standard SpalartAllmaras(SA) model. The Reynolds number is 4.0×105 in this calculation. The region is three-dimensional. Since the wind barrier and trains are almost invariable cross-sections, only 25 m along the track is modeled. The height of embankment ranges from 1 m to 5 m and the wind barrier is 3 m high. The results show that the wind speed changes obviously before the wind barrier on the horizontal plane, which is 4.5 m high above the track. The speed of wind reduces gradually while approaching the wind barrier. It reaches the minimum value at a distance about 5 m before the wind barrier, and increases dramatically afterwards. The speed of wind at this location is linear with the speed of far field. The train aerodynamic coefficients decrease sharply with the increment of the embankment height. And they take up the monotonicity. Meanwhile, when the height increases from 3 m to 5 m, they just change slightly. It is concluded that the optimum anemometer location is nearly 5 m in front of the wind barrier.展开更多
We derived revised effective diffusion energy barriers following the Boltzmann distribution assumption for impurity atoms in a bulk material under the impact of various kinds of point defects to reveal the insights of...We derived revised effective diffusion energy barriers following the Boltzmann distribution assumption for impurity atoms in a bulk material under the impact of various kinds of point defects to reveal the insights of migration mechanisms. The effective diffusion energy barriers of copper impurities in bulk zirconium were calculated through the first principle method under the presented hypothesis. Our results(?E_(||) =1.27 eV, ?E_⊥=1.31 eV) agreed well with the experimental results(?E_(||) =1.54 eV, ?E_⊥=1.60 eV), which validated bulk diffusion as the major mechanism for copper diffusion in zirconium. The effective diffusion energy barriers could be used for estimating whether the defects will accelerate the diffusion or slow them down by acting as traps of the impurity atoms. On the other hand, the first principle results of the impurity diffusion via defects could be further used as inputs of larger scale computational simulations, such as MC(Monte Carlo) or Phase Field calculations.展开更多
Pulsed dielectric barrier discharge(PDBD) exhibits several applications in different fields;however,the interaction of its components with substances remains a key issue.In this study,we employed experimental and nume...Pulsed dielectric barrier discharge(PDBD) exhibits several applications in different fields;however,the interaction of its components with substances remains a key issue.In this study,we employed experimental and numerical modeling to investigate the interactions between different PDBD components and substances in pure helium and a helium-oxygen mixture.A membrane comprising a Staphylococcus aureus strain was utilized as the treatment object to demonstrate the trace actions of the evolutions and distributions of certain components on the surface of the substance.The results revealed that the shapes and sizes of the discharging area and inhibition zone differed between groups.Under a pure helium condition,a discharge layer existed along the membrane surface,lying beside the main discharging channel within the electrode area.Further,an annulus inhibition zone was formed at the outer edge of the electrode in the pure helium group at 30 s and 1 min,and this zone extended to a solid circle at 2 min with a radius that was~50% larger than that of the electrode radius.Nevertheless,the discharging channel and inhibition zone in the helium-oxygen mixture were constrained inside the electrode area without forming any annulus.A 2D symmetrical model was developed with COMSOL to simulate the spatiotemporal distributions of different particles over the membrane surface,and the result demonstrated that the main components,which formed the annulus inhibition zone under the pure helium condition,contributed to the high concentration of the He^(+)annulus that was formed at the outer edge of the electrode.Moreover,O^(+)and O_(2)^(+)were the main components that killed the bacteria under the helium-oxygen mixture conditions.These results reveal that the homogenization treatment on a material surface via PDBD is closely related to the treatment time and working gas.展开更多
The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field dis...The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified.It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap.The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode.The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature,which is beneficial for industrial applications.This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD,which can provide some references for the development and applications of the DBD in the future.展开更多
The excitation function of quasi-elastic （QEL） scattering at a backward angle has been measured for 9^Be＋208^Pb. The barrier distribution was extracted by means of the first derivative of the measured excitation fu...The excitation function of quasi-elastic （QEL） scattering at a backward angle has been measured for 9^Be＋208^Pb. The barrier distribution was extracted by means of the first derivative of the measured excitation function and calculated with the coupled-channel model. The present work shows that the experimental barrier distribution extracted from QEL scattering is shifted to the low energy side by 1.5 MeV as compared with the theoretical one. This energy discrepancy indicates that breakup is important in the colliding processes of the weakly bound nucleus system.展开更多
The effect of different barriers between green and blue light regions in dual wavelength light emitting diodes was studied. Compared with a traditional sample, electroluminescence and photoluminescence spectra of the ...The effect of different barriers between green and blue light regions in dual wavelength light emitting diodes was studied. Compared with a traditional sample, electroluminescence and photoluminescence spectra of the newly designed samples showed peak intensity improvements and smaller blue-shifts with increasing injection current level, and the bottom quantum-wells light emitting is enhanced. All these phenomena can be ascribed to reduced barrier thickness and indium doping in the quantum-barrier influencing electric fields and more holes injecting into the bottom QWs.展开更多
The interaction potential between a spherical and a deformed nucleus is calculated within the double-folding model for deformed nuclei. We solve the double folding potential numerically by using the truncated multipol...The interaction potential between a spherical and a deformed nucleus is calculated within the double-folding model for deformed nuclei. We solve the double folding potential numerically by using the truncated multipole expansion method. The shape, separation and orientation dependence of the interaction potential, fusion cross section and barrier distribution of the system ^16O＋^154Sm are investigated by considering the quadrupole and hexadecapole deformations of ^154Sm. It is shown that the height and the position of the barrier depend strongly on the deformation and the orientation angles of the deformed nucleus. These are quite important quantities for heavy-ion fusion reactions, and hence produce great effects on the fusion cross section and barrier distribution.展开更多
A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneou...A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneously with a unique potential.The expectation value of the imaginary part of the potential calculated using the distorted waves from the full potential in the elastic channel accounts for σ_(r).This is equated to the sum of the cross-sections due to absorption in different regions of the potential where the imaginary part is actively present.The potential is taken as energy independent and features a weakly absorbing nature,which supports the resonance states in various partial wave trajectories.Therefore,these resonances show oscillatory behavior changes with respect to energy D(E_(c.m.))=d^(2)(E_(c.m.)σ_(fus))/dE_(c.m.)^(2).In this paper,we discuss elastic scattering and fusion cross-sections in conjunction with the results of D(E_(c.m.))for the^(16)+^(92)Zr system.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51172192,11272275 and 11002122)the Natural Science Foundation of Hunan Province(Grant No.11JJ4003)the Doctoral Scientific Research Foundation of Xiangtan University(Grant Nos.KZ08022,KZ03013 and KF20140303)
文摘To study the temperature distribution and thermal-stress field in different service stages, a two-dimensional model of a turbine blade with thermal barrier coatings is developed, in which the conjugate heat transfer analysis and the decoupled thermal-stress calculation method are adopted. Based on the simulation results, it is found that a non-uniform distribution of temperature appears in different positions of the blade surface, which has directly impacted on stress field. The maximum temperature with a value of 1030 ℃ occurs at the leading edge. During the steady stage, the maximum stress of thermally grown oxide （TGO） appears in the middle of the suction side, reaching 3.75 GPa. At the end stage of cooling, the maximum compressive stress of TGO with a value of-3.5 GPa occurs at the leading edge. Thus, it can be predicted that during the steady stage the dangerous regions may locate at the suction side, while the leadine edge mav be more Drone to failure on cooling.
基金financial support from the Interdisciplinary Fund of the Wuhan National High Magnetic Field Center (No. WHMFC202101)。
文摘The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.
基金The Natural Science Foundation of Shandong Province of China,Grant/Award Number:ZR2023YQ005The DAAD-K.C.Wong Postdoctoral Fellowships。
文摘With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common protective measure used in this country and abroad.The acoustic performance of a sound barrier is highly dependent on its shape and material.In this paper,a semianalytical meshless Burton-Miller‐type singular boundary method is proposed to analyze the acoustic performance of various shapes of sound barriers,and the distribution of sound‐absorbing materials on the surface of sound barriers is optimized by combining a solid isotropic material with a penalization method.The acoustic effect of the sound‐absorbing material is simplified as the acoustical impedance boundary condition.The objective of optimization is to minimize the sound pressure in a given reference plane.The volume of the sound‐absorbing material is used as a constraint.The density of the nodes covered with the sound‐absorbing material is used as the design variable.The method of moving asymptotes was used to update the design variables.This model completely avoids the mesh discretization process in the finite element method and requires only boundary nodes.In addition,the approach also does not require the singular integral calculation in the boundary element method.The method is illustrated and validated using numerical examples to demonstrate its accuracy and efficiency.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.51509035 and 51409158)the Project of Shenyang Science and Technology Bureau (Grant No.RC200010)the National Natural Science Foundation of Liaoning Province of China (Grant No.2020-KF-13-03)。
文摘In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge,a self-designed two-dimensional axisymmetric structure exciter was used to carry out optical diagnosis,with the electron temperature calculated through Gaussian fitting.A plasma model was applied to conduct research on the discharge process through numerical simulation,with the changes in electron density and electron temperature were analyzed by using different discharge parameters.The research results show that with an increase in discharge voltage,pressure inside the reactor and relative permittivity,the discharge process is promoted.In addition,a rise in current density leads to an increase in the number of charged particles on the surface of the medium during the discharge process,while a rise in discharge intensity causes an increase in the electron density.Electron temperature decreases due to the increased loss of collision energy between particles.These results were confirmed by comparing experimental data with simulation results.
基金supported by the Ministry of Science and Technology of China(2016YFA0201600 and 2016YFE0133100)the Program for International S&T Cooperation Projects of the Ministry of Science and Technology of China(2018YFE0117200)+5 种基金the National Natural Science Foundation of China(31800844 and 51861145302)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(11621505)the Major Research Program of Guangdong province(2019B090917011)the CAS Key Research Program for Frontier Sciences(QYZDJ-SSW-SLH022)the Austrian-Chinese Cooperative RTD Project(GJHZ201949,FFG and CAS)the CAS interdisciplinary innovation team。
文摘Due to their many advantageous properties,nanomaterials(NMs)have been utilized in diverse consumer goods,industrial products,and for therapeutic purposes.This situation leads to a constant risk of exposure and uptake by the human body,which are highly dependent on nanomaterial size.Consequently,an improved understanding of the interactions between different sizes of nanomaterials and biological systems is needed to design safer and more clinically relevant nano systems.We discuss the sizedependent effects of nanomaterials in living organisms.Upon entry into biological systems,nanomaterials can translocate biological barriers,distribute to various tissues and elicit different toxic effects on organs,based on their size and location.The association of nanomaterial size with physiological structures within organs determines the site of accumulation of nanoparticles.In general,nanomaterials smaller than 20 nm tend to accumulate in the kidney while nanomaterials between 20 and 100 nm preferentially deposit in the liver.After accumulating in organs,nanomaterials can induce inflammation,damage structural integrity and ultimately result in organ dysfunction,which helps better understand the size-dependent dynamic processes and toxicity of nanomaterials in organisms.The enhanced permeability and retention effect of nanomaterials and the utility of this phenomenon in tumor therapy are also highlighted.
基金Projects(51075401,U1334205)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0833)supported by the New Century Excellent Talents in University,China+2 种基金Project supported by the Scholarship Award for Excellent Innovative Doctoral Student granted by Central South University,ChinaProject(2012T002-E)supported by the Science and Technology Research and Development Program of Ministry of Railway,ChinaProject(14JJ1003)supported by the Natural Science Foundation of Hunan Province,China
文摘Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simulation(DES) with standard SpalartAllmaras(SA) model. The Reynolds number is 4.0×105 in this calculation. The region is three-dimensional. Since the wind barrier and trains are almost invariable cross-sections, only 25 m along the track is modeled. The height of embankment ranges from 1 m to 5 m and the wind barrier is 3 m high. The results show that the wind speed changes obviously before the wind barrier on the horizontal plane, which is 4.5 m high above the track. The speed of wind reduces gradually while approaching the wind barrier. It reaches the minimum value at a distance about 5 m before the wind barrier, and increases dramatically afterwards. The speed of wind at this location is linear with the speed of far field. The train aerodynamic coefficients decrease sharply with the increment of the embankment height. And they take up the monotonicity. Meanwhile, when the height increases from 3 m to 5 m, they just change slightly. It is concluded that the optimum anemometer location is nearly 5 m in front of the wind barrier.
基金Funded in Part by National Natural Science Foundation of China(Nos.11575129 and 11275142)
文摘We derived revised effective diffusion energy barriers following the Boltzmann distribution assumption for impurity atoms in a bulk material under the impact of various kinds of point defects to reveal the insights of migration mechanisms. The effective diffusion energy barriers of copper impurities in bulk zirconium were calculated through the first principle method under the presented hypothesis. Our results(?E_(||) =1.27 eV, ?E_⊥=1.31 eV) agreed well with the experimental results(?E_(||) =1.54 eV, ?E_⊥=1.60 eV), which validated bulk diffusion as the major mechanism for copper diffusion in zirconium. The effective diffusion energy barriers could be used for estimating whether the defects will accelerate the diffusion or slow them down by acting as traps of the impurity atoms. On the other hand, the first principle results of the impurity diffusion via defects could be further used as inputs of larger scale computational simulations, such as MC(Monte Carlo) or Phase Field calculations.
基金supported by National Natural Science Foundation of China(No.51907076)the Interdisciplinary Fund of the Wuhan National High Magnetic Field Center(No.WHMFC202101)
文摘Pulsed dielectric barrier discharge(PDBD) exhibits several applications in different fields;however,the interaction of its components with substances remains a key issue.In this study,we employed experimental and numerical modeling to investigate the interactions between different PDBD components and substances in pure helium and a helium-oxygen mixture.A membrane comprising a Staphylococcus aureus strain was utilized as the treatment object to demonstrate the trace actions of the evolutions and distributions of certain components on the surface of the substance.The results revealed that the shapes and sizes of the discharging area and inhibition zone differed between groups.Under a pure helium condition,a discharge layer existed along the membrane surface,lying beside the main discharging channel within the electrode area.Further,an annulus inhibition zone was formed at the outer edge of the electrode in the pure helium group at 30 s and 1 min,and this zone extended to a solid circle at 2 min with a radius that was~50% larger than that of the electrode radius.Nevertheless,the discharging channel and inhibition zone in the helium-oxygen mixture were constrained inside the electrode area without forming any annulus.A 2D symmetrical model was developed with COMSOL to simulate the spatiotemporal distributions of different particles over the membrane surface,and the result demonstrated that the main components,which formed the annulus inhibition zone under the pure helium condition,contributed to the high concentration of the He^(+)annulus that was formed at the outer edge of the electrode.Moreover,O^(+)and O_(2)^(+)were the main components that killed the bacteria under the helium-oxygen mixture conditions.These results reveal that the homogenization treatment on a material surface via PDBD is closely related to the treatment time and working gas.
基金supported by the Science and Technology Innovation Commission of Shenzhen(No.JCYJ20180507181858539)Shenzhen Science and Technology Program(No.KQTD20180412181422399)the National Key R&D Program of China(No.2019YFB2204500).
文摘The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified.It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap.The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode.The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature,which is beneficial for industrial applications.This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD,which can provide some references for the development and applications of the DBD in the future.
基金supported by National Natural Science Foundation of China (Nos.10575134,10675169,10735100)Major State Basic Research Developing Program (No.2007CB815003)
文摘The excitation function of quasi-elastic （QEL） scattering at a backward angle has been measured for 9^Be＋208^Pb. The barrier distribution was extracted by means of the first derivative of the measured excitation function and calculated with the coupled-channel model. The present work shows that the experimental barrier distribution extracted from QEL scattering is shifted to the low energy side by 1.5 MeV as compared with the theoretical one. This energy discrepancy indicates that breakup is important in the colliding processes of the weakly bound nucleus system.
基金supported by the National Natural Science Foundation of China(No.61274040)
文摘The effect of different barriers between green and blue light regions in dual wavelength light emitting diodes was studied. Compared with a traditional sample, electroluminescence and photoluminescence spectra of the newly designed samples showed peak intensity improvements and smaller blue-shifts with increasing injection current level, and the bottom quantum-wells light emitting is enhanced. All these phenomena can be ascribed to reduced barrier thickness and indium doping in the quantum-barrier influencing electric fields and more holes injecting into the bottom QWs.
基金National Natural Science Foundation of China (60572177)
文摘The interaction potential between a spherical and a deformed nucleus is calculated within the double-folding model for deformed nuclei. We solve the double folding potential numerically by using the truncated multipole expansion method. The shape, separation and orientation dependence of the interaction potential, fusion cross section and barrier distribution of the system ^16O＋^154Sm are investigated by considering the quadrupole and hexadecapole deformations of ^154Sm. It is shown that the height and the position of the barrier depend strongly on the deformation and the orientation angles of the deformed nucleus. These are quite important quantities for heavy-ion fusion reactions, and hence produce great effects on the fusion cross section and barrier distribution.
文摘A partial wave scattering matrix for the total effective complex potential of nucleus nucleus collisions is proposed to easily analyze the angular variations of elastic scattering and fusion cross-sections simultaneously with a unique potential.The expectation value of the imaginary part of the potential calculated using the distorted waves from the full potential in the elastic channel accounts for σ_(r).This is equated to the sum of the cross-sections due to absorption in different regions of the potential where the imaginary part is actively present.The potential is taken as energy independent and features a weakly absorbing nature,which supports the resonance states in various partial wave trajectories.Therefore,these resonances show oscillatory behavior changes with respect to energy D(E_(c.m.))=d^(2)(E_(c.m.)σ_(fus))/dE_(c.m.)^(2).In this paper,we discuss elastic scattering and fusion cross-sections in conjunction with the results of D(E_(c.m.))for the^(16)+^(92)Zr system.
