The entropy density, energy density, pressure and equation of state around the RNAdS black hole are calculated in the WKB approximation on the Teukolsky-type master equation. The appearance of spin-dependent terms is ...The entropy density, energy density, pressure and equation of state around the RNAdS black hole are calculated in the WKB approximation on the Teukolsky-type master equation. The appearance of spin-dependent terms is demonstrated. The existence of these terms shows that the black hole radiation is not exactly thermal radiation and the black hole entropy is not strictly proportional to the area of the event horizon.展开更多
Photodetachment of negative ions has attracted immense interest owing to its fundamental nature and practical implications with regard to technology. In this study, we explore the quantum dynamics of the photodetachme...Photodetachment of negative ions has attracted immense interest owing to its fundamental nature and practical implications with regard to technology. In this study, we explore the quantum dynamics of the photodetachment cross section of negative ion of hydrogen H-in the perturbed one dimensional linear harmonic potential via static electric field. To this end,the quantum formula for total photodetachment cross section of the H-ion is derived by calculating the dipole matrix element in spherical coordinates. In order to obtain the detached electron wave function, we have solved the time-independent Schr¨odinger wave equation for the perturbed Hamiltonian of the harmonic oscillator in momentum representation. To acquire the corresponding normalized final state detached electron wave function in momentum space, we have employed an approach analogous to the WKB(Wenzel–Kramers–Brillouin) approximation. The resulting analytical formula of total photodetachment cross section depicts interesting oscillator structure that varies considerably with incident-photon energy,oscillator potential frequency, and electric field strength as elucidated by the numerical results. The current problem having close analogy with the Stark effect in charged harmonic oscillator may have potential implications in atomic and molecular physics and quantum optics.展开更多
In this paper, using the third-order WKB approximation, we investigate the quasinormal frequencies of the scalar field in the background of a five-dimensional Lovelock black hole. We find that the ultraviolet correcti...In this paper, using the third-order WKB approximation, we investigate the quasinormal frequencies of the scalar field in the background of a five-dimensional Lovelock black hole. We find that the ultraviolet correction to Einstein theory in the Lovelock theory makes the scalar field decay more slowly and oscillate more quickly, and the cosmological constant makes the scalar field decay more slowly and oscillate more slowly in the Lovelock black hole background.展开更多
The unsteady oscillatory flow of an incompressible second grade fluid in a cylindrical tube with large wall suction is studied analytically. Flow in the tube is due to uniform suction at the permeable walls, and the o...The unsteady oscillatory flow of an incompressible second grade fluid in a cylindrical tube with large wall suction is studied analytically. Flow in the tube is due to uniform suction at the permeable walls, and the oscillations in the velocity field are due to small amplitude time harmonic pressure waves. The physical quantities of interest are the velocity field, the amplitude of oscillation, and the penetration depth of the oscillatory wave. The analytical solution of the governing boundary value problem is obtained, and the effects of second grade fluid parameters are analyzed and discussed.展开更多
A new analytical model was developed to predict the gravity wave drag (GWD) induced by an isolated 3-dimensional mountain, over which a stratified, nonrotating non-Boussinesq sheared flow is impinged. The model is c...A new analytical model was developed to predict the gravity wave drag (GWD) induced by an isolated 3-dimensional mountain, over which a stratified, nonrotating non-Boussinesq sheared flow is impinged. The model is confined to small amplitude motion and assumes the ambient velocity varying slowly with height. The modified Taylor-Goldstein equation with variable coefficients is solved with a Wentzel-Kramers-Brillouin (WKB) approximation, formally valid at high Richardson numbers. With this WKB solution, generic formulae of second order accuracy, for the GWD and surface pressure perturbation (both for hydrostatic and non-hydrostatic flow) are presented, enabling a rigorous treatment on the effects by vertical variations in wind profiles. In an ideal test to the circular bell-shaped mountain, itwas found that when the wind is linearly sheared, that the GWD decreases as the Richardson number decreases. However, the GWD for a forward sheared wind (wind increases with height) decreases always faster than that for the backward sheared wind (wind deceases with height). This difference is evident whenever the model is hydrostatic or not.展开更多
The present work explores the propagation characteristics of high-power beams in weakly relativistic-ponderomotive thermal quantum plasma.A q-Gaussian laser beam is taken in the present investigation.The quasi-optics ...The present work explores the propagation characteristics of high-power beams in weakly relativistic-ponderomotive thermal quantum plasma.A q-Gaussian laser beam is taken in the present investigation.The quasi-optics equation obtained in the present study is solved through a well-established Wentzel–Kramers–Brillouin approximation and paraxial theory approach for obtaining the second-order differential equation describing the behavior of beam width of the laser beam.Further,a numerical simulation of this second-order differential equation is carried out for determining the behavior of the beam width with dimensionless distance for established laser–plasma parameters.The comparison of the present study is made with ordinary quantum plasma and classical relativistic plasma cases.展开更多
In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter propose...In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter proposed by Wang et al.[Chin.Phys.C 45,044111(2021)],respectively,we extend a new simple model put forward by Bayrak[J.Phys.G 47,025102(2020)]to systematically study the cluster radioactivity half-lives of 28 trans-lead nuclei ranging from^(222)Fr to^(242)Cm,which is based on the Wentzel-Kramers-Brillouin approximation and Bohr–Sommerfeld quantization condition.For comparison,a universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a three-parameter model-independent formula put forward by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and the semi-empirical model proposed by Tavares et al.[Eur.Phys.J.A 49,1(2013)]are used.Our calculated results reproduce the experimental data well,with a standard deviation of 0.818.Furthermore,we use this model to predict the cluster radioactivity half-lives of 51 possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
In this paper the influences of nonuniform stratification on the propagating paths of internal inertial-gravity and pure gravity wave energy are discussed by using the WKB approximation method.The conditions for conse...In this paper the influences of nonuniform stratification on the propagating paths of internal inertial-gravity and pure gravity wave energy are discussed by using the WKB approximation method.The conditions for conservation of wave energy,generalized wave action and wave enstrophy are obtained.The necessary condition of instability for inter- nal gravity waves and the equation governing the refraction of wave rays are derived.Two types of critical levels are giv- en.Finally,the wave rays for different distributions of stratification are calculated by using the fourth-order Runge-Kutta method.展开更多
When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmosph...When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmospheric circulation, as well as the momentum and energy transport. Such sub-scale ographic forcing should be introduced into numerically atmospheric model by means of drag being parameterized. Furthermore, the currently mature ographic gravity wave drag (OGWD) parameterization, i.e., the so-called first-generation (based on lineal single-wave theoretical framework) or the second-generation drag parameterization (including an important extra forcing by the contribution of critical level absorption), cannot correctly and effectly describe the vertical profile of wave stress under the influence of ambient wind shearing. Based on aforementioned consideration, a new two-wave scheme was proposed to parameterize the ographic gravity wave drag by means of freely propagating gravity waves. It starts with a second order WKB approximation, and treats the wave stress attenuations caused by either the selective critical level absorption or the classical critical level absorption explicitly; while in the regions where critical levels are absent, it transports the wave stress vertically by two sinusoidal waves and deposits them and then damps them according to the wave saturation criteria. This scheme is thus used to conduct some sample computations over the Dabie Mountain region of East China, as an example. The results showed that the new two-wave scheme is able to model the vertical distribution of the wave stress more realistically.展开更多
The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized ...The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model(GLDM). The penetrability is calculated with the WentzelKramers-Brillouin(WKB) approximation. The spectroscopic factor has been taken into account in halflife calculation, which is obtained by employing the relativistic mean field(RMF) theory combined with the Bardeen-Cooper-Schrieffer(BCS) method. The half-lives within the present hybrid method reproduced the experimental data very well. Some predictions for proton radioactivity are made for future experiments.展开更多
Hierarchical Ag/SiO_(2)/TiO_(2) nanobowl(NB)arrays were fabricated for use as plasmonic photoanodes for solar-hydrogen conversion.The nanobowls had large pore size and were composed of an upper TiO_(2) nanoring and a ...Hierarchical Ag/SiO_(2)/TiO_(2) nanobowl(NB)arrays were fabricated for use as plasmonic photoanodes for solar-hydrogen conversion.The nanobowls had large pore size and were composed of an upper TiO_(2) nanoring and a lower TiO_(2) nanohole.A thin SiO_(2) inter-layer was introduced as an electron transmission channel to change the mechanism of hot electron transport.Simulations were performed to characterize the variation of electron concentration in Ag/SiO_(2)/TiO_(2) NB arrays,taking into account both the optical transition of photogenerated electrons,and electron tunneling.The multiphysics coupling function of COMSOL software provided the light source for optical transition of photogenerated electrons,and a Wentzel-Kramers-Brillouin model was employed to represent the tunneling.The results demonstrate that the TiO_(2) nanoring was a transporter,which transmitted electrons downward to the nanohole.The SiO_(2) layer replaces the Schottky barrier to become a bridge for tunneling of hot electrons in high-and low-energy states into TiO_(2).Moreover,the coverage of the SiO_(2) layer helped increase the light absorption of TiO_(2),it also reduced the near electric field coupling between Ag and TiO_(2).Accordingly,under AM 1.5 light irradiation,the photocurrent density and average hydrogen evolution rate of Ag/SiO_(2)/TiO_(2) were 1.8 and 2.2 times higher,respectively,than those of pure TiO_(2),implying far more efficient migration of carriers.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10375051).
文摘The entropy density, energy density, pressure and equation of state around the RNAdS black hole are calculated in the WKB approximation on the Teukolsky-type master equation. The appearance of spin-dependent terms is demonstrated. The existence of these terms shows that the black hole radiation is not exactly thermal radiation and the black hole entropy is not strictly proportional to the area of the event horizon.
文摘Photodetachment of negative ions has attracted immense interest owing to its fundamental nature and practical implications with regard to technology. In this study, we explore the quantum dynamics of the photodetachment cross section of negative ion of hydrogen H-in the perturbed one dimensional linear harmonic potential via static electric field. To this end,the quantum formula for total photodetachment cross section of the H-ion is derived by calculating the dipole matrix element in spherical coordinates. In order to obtain the detached electron wave function, we have solved the time-independent Schr¨odinger wave equation for the perturbed Hamiltonian of the harmonic oscillator in momentum representation. To acquire the corresponding normalized final state detached electron wave function in momentum space, we have employed an approach analogous to the WKB(Wenzel–Kramers–Brillouin) approximation. The resulting analytical formula of total photodetachment cross section depicts interesting oscillator structure that varies considerably with incident-photon energy,oscillator potential frequency, and electric field strength as elucidated by the numerical results. The current problem having close analogy with the Stark effect in charged harmonic oscillator may have potential implications in atomic and molecular physics and quantum optics.
基金Project supported by the National Natural Science Foundation of China (Grant No.10873004)the Key Project of the National Natural Science Foundation of China (Grant No.10935013)+1 种基金the Scientific Research Fund of the Educational Department of Hunan Province of China (Grant No.08B051)the Program for Excellent Talents in Hunan Normal University and the State Key Development Program for Basic Research Program of China (Grant No.2010CB832803)
文摘In this paper, using the third-order WKB approximation, we investigate the quasinormal frequencies of the scalar field in the background of a five-dimensional Lovelock black hole. We find that the ultraviolet correction to Einstein theory in the Lovelock theory makes the scalar field decay more slowly and oscillate more quickly, and the cosmological constant makes the scalar field decay more slowly and oscillate more slowly in the Lovelock black hole background.
文摘The unsteady oscillatory flow of an incompressible second grade fluid in a cylindrical tube with large wall suction is studied analytically. Flow in the tube is due to uniform suction at the permeable walls, and the oscillations in the velocity field are due to small amplitude time harmonic pressure waves. The physical quantities of interest are the velocity field, the amplitude of oscillation, and the penetration depth of the oscillatory wave. The analytical solution of the governing boundary value problem is obtained, and the effects of second grade fluid parameters are analyzed and discussed.
基金Project supported by the National Basic Research Program of China (973 Program) (No.2004CB418301)the National Natural Science Foundation of China(Nos.40575017 and 40333031)
文摘A new analytical model was developed to predict the gravity wave drag (GWD) induced by an isolated 3-dimensional mountain, over which a stratified, nonrotating non-Boussinesq sheared flow is impinged. The model is confined to small amplitude motion and assumes the ambient velocity varying slowly with height. The modified Taylor-Goldstein equation with variable coefficients is solved with a Wentzel-Kramers-Brillouin (WKB) approximation, formally valid at high Richardson numbers. With this WKB solution, generic formulae of second order accuracy, for the GWD and surface pressure perturbation (both for hydrostatic and non-hydrostatic flow) are presented, enabling a rigorous treatment on the effects by vertical variations in wind profiles. In an ideal test to the circular bell-shaped mountain, itwas found that when the wind is linearly sheared, that the GWD decreases as the Richardson number decreases. However, the GWD for a forward sheared wind (wind increases with height) decreases always faster than that for the backward sheared wind (wind deceases with height). This difference is evident whenever the model is hydrostatic or not.
文摘The present work explores the propagation characteristics of high-power beams in weakly relativistic-ponderomotive thermal quantum plasma.A q-Gaussian laser beam is taken in the present investigation.The quasi-optics equation obtained in the present study is solved through a well-established Wentzel–Kramers–Brillouin approximation and paraxial theory approach for obtaining the second-order differential equation describing the behavior of beam width of the laser beam.Further,a numerical simulation of this second-order differential equation is carried out for determining the behavior of the beam width with dimensionless distance for established laser–plasma parameters.The comparison of the present study is made with ordinary quantum plasma and classical relativistic plasma cases.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the Construct Program of the Key Discipline in Hunan Province,the Research Foundation of the Education Bureau of Hunan Province,China(18A237)+2 种基金the Natural Science Foundation of Shandong Province,China(ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)the Innovation Group of Nuclear and Particle Physics in USC,the Innovation Foundation for Postgraduate of Hunan Province,China(CX20230962)。
文摘In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter proposed by Wang et al.[Chin.Phys.C 45,044111(2021)],respectively,we extend a new simple model put forward by Bayrak[J.Phys.G 47,025102(2020)]to systematically study the cluster radioactivity half-lives of 28 trans-lead nuclei ranging from^(222)Fr to^(242)Cm,which is based on the Wentzel-Kramers-Brillouin approximation and Bohr–Sommerfeld quantization condition.For comparison,a universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a three-parameter model-independent formula put forward by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and the semi-empirical model proposed by Tavares et al.[Eur.Phys.J.A 49,1(2013)]are used.Our calculated results reproduce the experimental data well,with a standard deviation of 0.818.Furthermore,we use this model to predict the cluster radioactivity half-lives of 51 possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in NUBASE2020.
基金This research is supported by the National Natural Science Foundation of China.
文摘In this paper the influences of nonuniform stratification on the propagating paths of internal inertial-gravity and pure gravity wave energy are discussed by using the WKB approximation method.The conditions for conservation of wave energy,generalized wave action and wave enstrophy are obtained.The necessary condition of instability for inter- nal gravity waves and the equation governing the refraction of wave rays are derived.Two types of critical levels are giv- en.Finally,the wave rays for different distributions of stratification are calculated by using the fourth-order Runge-Kutta method.
基金the State Natural Science Foundation of China under Grant Nos.40775034,40575017,and 90715031the Natural Science Foundation of Jiangsu under Grant No.BK99020the open project of State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences.
文摘When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmospheric circulation, as well as the momentum and energy transport. Such sub-scale ographic forcing should be introduced into numerically atmospheric model by means of drag being parameterized. Furthermore, the currently mature ographic gravity wave drag (OGWD) parameterization, i.e., the so-called first-generation (based on lineal single-wave theoretical framework) or the second-generation drag parameterization (including an important extra forcing by the contribution of critical level absorption), cannot correctly and effectly describe the vertical profile of wave stress under the influence of ambient wind shearing. Based on aforementioned consideration, a new two-wave scheme was proposed to parameterize the ographic gravity wave drag by means of freely propagating gravity waves. It starts with a second order WKB approximation, and treats the wave stress attenuations caused by either the selective critical level absorption or the classical critical level absorption explicitly; while in the regions where critical levels are absent, it transports the wave stress vertically by two sinusoidal waves and deposits them and then damps them according to the wave saturation criteria. This scheme is thus used to conduct some sample computations over the Dabie Mountain region of East China, as an example. The results showed that the new two-wave scheme is able to model the vertical distribution of the wave stress more realistically.
基金National Natural Science Foundation of China(11175074,11475050,11265013)Knowledge Innovation Project of Chinese Academy of Sciences(KJCX2-EW-N02)
文摘The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model(GLDM). The penetrability is calculated with the WentzelKramers-Brillouin(WKB) approximation. The spectroscopic factor has been taken into account in halflife calculation, which is obtained by employing the relativistic mean field(RMF) theory combined with the Bardeen-Cooper-Schrieffer(BCS) method. The half-lives within the present hybrid method reproduced the experimental data very well. Some predictions for proton radioactivity are made for future experiments.
基金the National Natural Science Foundation of China(No.51776009)for their financial support.
文摘Hierarchical Ag/SiO_(2)/TiO_(2) nanobowl(NB)arrays were fabricated for use as plasmonic photoanodes for solar-hydrogen conversion.The nanobowls had large pore size and were composed of an upper TiO_(2) nanoring and a lower TiO_(2) nanohole.A thin SiO_(2) inter-layer was introduced as an electron transmission channel to change the mechanism of hot electron transport.Simulations were performed to characterize the variation of electron concentration in Ag/SiO_(2)/TiO_(2) NB arrays,taking into account both the optical transition of photogenerated electrons,and electron tunneling.The multiphysics coupling function of COMSOL software provided the light source for optical transition of photogenerated electrons,and a Wentzel-Kramers-Brillouin model was employed to represent the tunneling.The results demonstrate that the TiO_(2) nanoring was a transporter,which transmitted electrons downward to the nanohole.The SiO_(2) layer replaces the Schottky barrier to become a bridge for tunneling of hot electrons in high-and low-energy states into TiO_(2).Moreover,the coverage of the SiO_(2) layer helped increase the light absorption of TiO_(2),it also reduced the near electric field coupling between Ag and TiO_(2).Accordingly,under AM 1.5 light irradiation,the photocurrent density and average hydrogen evolution rate of Ag/SiO_(2)/TiO_(2) were 1.8 and 2.2 times higher,respectively,than those of pure TiO_(2),implying far more efficient migration of carriers.