Considering that the fluid is inviscid and incompressible and the flow is irrotational in a fixed frame of reference and using the multiple scale analysis method, we derive a nonlinear Schrodinger equation(NLSE) descr...Considering that the fluid is inviscid and incompressible and the flow is irrotational in a fixed frame of reference and using the multiple scale analysis method, we derive a nonlinear Schrodinger equation(NLSE) describing the evolution dynamics of gravity-capillary wavetrains in arbitrary constant depth. The gravity-capillary waves(GCWs) are influenced by a linear shear flow(LSF) which consists of a uniform flow and a shear flow with constant vorticity. The modulational instability(MI) of GCWs with the LSF is analyzed using the NLSE. The MI is effectively modified by the LSF. In infinite depth, there are four asymptotes which are the boundaries between MI and modulational stability(MS) in the instability diagram. In addition, the dimensionless free surface elevation as a function of time for different dimensionless water depth,surface tension, uniform flow and vorticity is exhibited. It is found that the decay of free surface elevation and the steepness of free surface amplitude change over time, which are greatly affected by the water depth, surface tension, uniform flow and vorticity.展开更多
We study some nonlinear waves in a viscous plasma which is confined in a finite cylinder.By averaging the physical quantities on the radial direction in some cases,we reduce this system to a simple one-dimensional mod...We study some nonlinear waves in a viscous plasma which is confined in a finite cylinder.By averaging the physical quantities on the radial direction in some cases,we reduce this system to a simple one-dimensional model.It seems that the effects of the bounded geometry(the radius of the cylinder in this case)can be included in the damping coefficient.We notice that the amplitudes of both Korteweg–de Vries(KdV)solitary waves and dark envelope solitary waves decrease exponentially as time increases from the particle-in-cell(PIC)simulation.The dependence of damping coefficient on the cylinder radius and the viscosity coefficient is also obtained numerically and analytically.Both are in good agreement.By using a definition,we give a condition whether a solitary wave exists in a bounded plasma.Moreover,some of potential applications in laboratory experiments are suggested.展开更多
Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results ...Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the tropical Indian Ocean and the tropical Pacific Ocean, thus this wave packet can also explain the decadal variability(about 20 a) of the equatorial Pacific and Indian Oceans.展开更多
This article studies bounded traveling wave solutions of variant Boussinesq equation with a dissipation term and dissipation effect on them. Firstly, we make qualitative analysis to the bounded traveling wave solution...This article studies bounded traveling wave solutions of variant Boussinesq equation with a dissipation term and dissipation effect on them. Firstly, we make qualitative analysis to the bounded traveling wave solutions for the above equation by the theory and method of planar dynamical systems, and obtain their existent conditions, number, and general shape. Secondly, we investigate the dissipation effect on the shape evolution of bounded traveling wave solutions. We find out a critical value r^* which can characterize the scale of dissipation effect, and prove that the bounded traveling wave solutions appear as kink profile waves if |r|≥ r^*; while they appear as damped oscillatory waves if |r| 〈 r^*. We also obtain kink profile solitary wave solutions with and without dissipation effect. On the basis of the above discussion, we sensibly design the structure of the approximate damped oscillatory solutions according to the orbits evolution relation corresponding to the component u(ξ) in the global phase portraits, and then obtain the approximate solutions (u(ξ), H(ξ)). Furthermore, by using homogenization principle, we give their error estimates by establishing the integral equation which reflects the relation between exact and approximate solutions. Finally, we discuss the dissipation effect on the amplitude, frequency, and energy decay of the bounded traveling wave solutions.展开更多
Alinhac solved a long-standing open problem in 2001 and established that quasilinear wave equations in two space dimensions with quadratic null nonlinearities admit global-in-time solutions,provided that the initial d...Alinhac solved a long-standing open problem in 2001 and established that quasilinear wave equations in two space dimensions with quadratic null nonlinearities admit global-in-time solutions,provided that the initial data are compactly supported and sufficiently small in Sobolev norm.In this work,Alinhac obtained an upper bound with polynomial growth in time for the top-order energy of the solutions.A natural question then arises whether the time-growth is a true phenomenon,despite the possible conservation of basic energy.In the present paper,we establish that the top-order energy of the solutions in Alinhac theorem remains globally bounded in time.展开更多
Photonic bound states in the continuum(BICs)are spatially localized modes with infinitely long lifetimes,which exist within a radiation continuum at discrete energy levels.These states have been explored in various sy...Photonic bound states in the continuum(BICs)are spatially localized modes with infinitely long lifetimes,which exist within a radiation continuum at discrete energy levels.These states have been explored in various systems,including photonic and phononic crystal slabs,metasurfaces,waveguides,and integrated circuits.Robustness and availability of the BICs are important aspects for fully taming the BICs toward practical applications.Here,we propose a generic mechanism to realize BICs that exist by first principles free of fine parameter tuning based on non-Maxwellian double-net metamaterials(DNMs).An ideal warm hydrodynamic double plasma(HDP)fluid model provides a homogenized description of DNMs and explains the robustness of the BICs found herein.In the HDP model,these are standing wave formations made of electron acoustic waves(EAWs),which are pure charge oscillations with vanishing electromagnetic fields.EAW BICs have various advantages,such as(i)frequency-comb-like collection of BICs free from normal resonances;(ii)robustness to symmetry-breaking perturbations and formation of quasi-BICs with an ultrahigh Q-factor even if subject to disorder;and(iii)giving rise to subwavelength microcavity resonators hosting quasi-BIC modes with an ultrahigh Q-factor.展开更多
We develop a new full waveform inversion (FWI) method for slowness with the crosshole data based on the acoustic wave equation in the time domain. The method combines the total variation (TV) regularization with the c...We develop a new full waveform inversion (FWI) method for slowness with the crosshole data based on the acoustic wave equation in the time domain. The method combines the total variation (TV) regularization with the constrained optimization together which can inverse the slowness effectively. One advantage of slowness inversion is that there is no further approximation in the gradient derivation. Moreover, a new algorithm named the skip method for solving the constrained optimization problem is proposed. The TV regularization has good ability to inverse slowness at its discontinuities while the constrained optimization can keep the inversion converging in the right direction. Numerical computations both for noise free data and noisy data show the robustness and effectiveness of our method and good inversion results are yielded.展开更多
On the basis of the new type Boussinesq equations (Madsen et al., 2002), a set of equations explicitly including the effects of currents on waves are derived. A numerical implementation of the present equations in o...On the basis of the new type Boussinesq equations (Madsen et al., 2002), a set of equations explicitly including the effects of currents on waves are derived. A numerical implementation of the present equations in one dimension is described. The numerical model is tested for wave propagation in a wave flume of uniform depth with current present. The present numerical results are compared with those of other researchers. It is validated that the present numerical model can reasonably reflect the nonlinear influences of currents on waves. Moreover, the effects of inputting different incident boundary conditions on the calculated results are studied.展开更多
The anti-periodic traveling wave solutions to a forced two-dimensional generalized KdV-Burgers equation are studied. Some theorems concerning the boundness, existence and uniqueness of the solution to this equation ar...The anti-periodic traveling wave solutions to a forced two-dimensional generalized KdV-Burgers equation are studied. Some theorems concerning the boundness, existence and uniqueness of the solution to this equation are proved.展开更多
This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of pla...This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of planar dynamical systems are used to make a qualitative analysis to the planar dynamical system which the bounded traveling wave solutions of this equation correspond to. The shapes, existent number, and condi- tions are presented for all bounded traveling wave solutions. The bounded traveling wave solutions are obtained by the undetermined coefficients method according to their shapes, including exact expressions of bell and kink profile solitary wave solutions and approxi- mate expressions of damped oscillatory solutions. For the approximate damped oscillatory solution, using the homogenization principle, its error estimate is given by establishing the integral equation, which reflects the relation between the exact and approximate so- lutions. It can be seen that the error is infinitesimal decreasing in the exponential form.展开更多
We investigate the bound state problem in a one-dimensional flat band system with a Coulomb potential.It is found that,in the presence of a Coulomb potential of type I(with three equal diagonal elements),similarly to ...We investigate the bound state problem in a one-dimensional flat band system with a Coulomb potential.It is found that,in the presence of a Coulomb potential of type I(with three equal diagonal elements),similarly to that in the twodimensional case,the flat band could not survive.At the same time,the flat band states are transformed into localized states with a logarithmic singularity near the center position.In addition,the wave function near the origin would collapse for an arbitrarily weak Coulomb potential.Due to the wave function collapses,the eigen-energies for a shifted Coulomb potential depend sensitively on the cut-off parameter.For a Coulomb potential of type II,there exist infinite bound states that are generated from the flat band.Furthermore,when the bound state energy is very near the flat band,the energy is inversely proportional to the natural number,e.g.,E_(n)∝1/n,n=1,2,3,...It is expected that the 1/n energy spectrum could be observed experimentally in the near future.展开更多
We present solutions of the Schrodinger equation with superposition of Manning-Rosen plus inversely Mobius square plus quadratic Yukawa potentials using parametric Nikiforov Uvarov method along with an approximation t...We present solutions of the Schrodinger equation with superposition of Manning-Rosen plus inversely Mobius square plus quadratic Yukawa potentials using parametric Nikiforov Uvarov method along with an approximation to the centrifugal term. The bound state energy eigenvalues for any angular momentum quantum number <em>l</em> and the corresponding un-normalized wave functions are calculated. The mixed potential which in some particular cases gives the solutions for different potentials: the Manning-Rosen, the Mobius square, the inversely quadratic Yukawa and the Hulthén potentials along with their bound state energies are obtained.展开更多
An investigation of origins of the quantum mechanical momentum operator has shown that it corresponds to the nonrelativistic momentum of classical special relativity theory rather than the relativistic one, as has bee...An investigation of origins of the quantum mechanical momentum operator has shown that it corresponds to the nonrelativistic momentum of classical special relativity theory rather than the relativistic one, as has been unconditionally believed in traditional relativistic quantum mechanics until now. Taking this correspondence into account, relativistic momentum and energy operators are defined. Schrödinger equations with relativistic kinematics are introduced and investigated for a free particle and a particle trapped in the deep potential well.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.41830533)the National Key Research and Development Program of China(Grant Nos.2016YFC1401404 and 2017YFA0604102).
文摘Considering that the fluid is inviscid and incompressible and the flow is irrotational in a fixed frame of reference and using the multiple scale analysis method, we derive a nonlinear Schrodinger equation(NLSE) describing the evolution dynamics of gravity-capillary wavetrains in arbitrary constant depth. The gravity-capillary waves(GCWs) are influenced by a linear shear flow(LSF) which consists of a uniform flow and a shear flow with constant vorticity. The modulational instability(MI) of GCWs with the LSF is analyzed using the NLSE. The MI is effectively modified by the LSF. In infinite depth, there are four asymptotes which are the boundaries between MI and modulational stability(MS) in the instability diagram. In addition, the dimensionless free surface elevation as a function of time for different dimensionless water depth,surface tension, uniform flow and vorticity is exhibited. It is found that the decay of free surface elevation and the steepness of free surface amplitude change over time, which are greatly affected by the water depth, surface tension, uniform flow and vorticity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11965019 and 11847142).
文摘We study some nonlinear waves in a viscous plasma which is confined in a finite cylinder.By averaging the physical quantities on the radial direction in some cases,we reduce this system to a simple one-dimensional model.It seems that the effects of the bounded geometry(the radius of the cylinder in this case)can be included in the damping coefficient.We notice that the amplitudes of both Korteweg–de Vries(KdV)solitary waves and dark envelope solitary waves decrease exponentially as time increases from the particle-in-cell(PIC)simulation.The dependence of damping coefficient on the cylinder radius and the viscosity coefficient is also obtained numerically and analytically.Both are in good agreement.By using a definition,we give a condition whether a solitary wave exists in a bounded plasma.Moreover,some of potential applications in laboratory experiments are suggested.
基金The National Major Research High Performance Computing Program of China under contract 2016YFB0200800the Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDA20060501
文摘Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the tropical Indian Ocean and the tropical Pacific Ocean, thus this wave packet can also explain the decadal variability(about 20 a) of the equatorial Pacific and Indian Oceans.
基金supported by National Natural ScienceFoundation of China(11071164)Innovation Program of Shanghai Municipal Education Commission(13ZZ118)Shanghai Leading Academic Discipline Project(XTKX2012)
文摘This article studies bounded traveling wave solutions of variant Boussinesq equation with a dissipation term and dissipation effect on them. Firstly, we make qualitative analysis to the bounded traveling wave solutions for the above equation by the theory and method of planar dynamical systems, and obtain their existent conditions, number, and general shape. Secondly, we investigate the dissipation effect on the shape evolution of bounded traveling wave solutions. We find out a critical value r^* which can characterize the scale of dissipation effect, and prove that the bounded traveling wave solutions appear as kink profile waves if |r|≥ r^*; while they appear as damped oscillatory waves if |r| 〈 r^*. We also obtain kink profile solitary wave solutions with and without dissipation effect. On the basis of the above discussion, we sensibly design the structure of the approximate damped oscillatory solutions according to the orbits evolution relation corresponding to the component u(ξ) in the global phase portraits, and then obtain the approximate solutions (u(ξ), H(ξ)). Furthermore, by using homogenization principle, we give their error estimates by establishing the integral equation which reflects the relation between exact and approximate solutions. Finally, we discuss the dissipation effect on the amplitude, frequency, and energy decay of the bounded traveling wave solutions.
基金supported by the China Postdoctoral Science Foundation(2021M690702)The author Z.L.was in part supported by NSFC(11725102)+2 种基金Sino-German Center(M-0548)the National Key R&D Program of China(2018AAA0100303)National Support Program for Young Top-Notch TalentsShanghai Science and Technology Program[21JC1400600 and No.19JC1420101].
文摘Alinhac solved a long-standing open problem in 2001 and established that quasilinear wave equations in two space dimensions with quadratic null nonlinearities admit global-in-time solutions,provided that the initial data are compactly supported and sufficiently small in Sobolev norm.In this work,Alinhac obtained an upper bound with polynomial growth in time for the top-order energy of the solutions.A natural question then arises whether the time-growth is a true phenomenon,despite the possible conservation of basic energy.In the present paper,we establish that the top-order energy of the solutions in Alinhac theorem remains globally bounded in time.
基金funding from the Swiss National Science Foundation (Grant No. 188647)from the Adolphe Merkle Foundation
文摘Photonic bound states in the continuum(BICs)are spatially localized modes with infinitely long lifetimes,which exist within a radiation continuum at discrete energy levels.These states have been explored in various systems,including photonic and phononic crystal slabs,metasurfaces,waveguides,and integrated circuits.Robustness and availability of the BICs are important aspects for fully taming the BICs toward practical applications.Here,we propose a generic mechanism to realize BICs that exist by first principles free of fine parameter tuning based on non-Maxwellian double-net metamaterials(DNMs).An ideal warm hydrodynamic double plasma(HDP)fluid model provides a homogenized description of DNMs and explains the robustness of the BICs found herein.In the HDP model,these are standing wave formations made of electron acoustic waves(EAWs),which are pure charge oscillations with vanishing electromagnetic fields.EAW BICs have various advantages,such as(i)frequency-comb-like collection of BICs free from normal resonances;(ii)robustness to symmetry-breaking perturbations and formation of quasi-BICs with an ultrahigh Q-factor even if subject to disorder;and(iii)giving rise to subwavelength microcavity resonators hosting quasi-BIC modes with an ultrahigh Q-factor.
文摘We develop a new full waveform inversion (FWI) method for slowness with the crosshole data based on the acoustic wave equation in the time domain. The method combines the total variation (TV) regularization with the constrained optimization together which can inverse the slowness effectively. One advantage of slowness inversion is that there is no further approximation in the gradient derivation. Moreover, a new algorithm named the skip method for solving the constrained optimization problem is proposed. The TV regularization has good ability to inverse slowness at its discontinuities while the constrained optimization can keep the inversion converging in the right direction. Numerical computations both for noise free data and noisy data show the robustness and effectiveness of our method and good inversion results are yielded.
基金supported by the National Natural Science Foundation of China (Grant No.40676053)theNational High Technology Research and Development Program of China (863 Program,Grant No.2006AA09A107)the Science and Technology Committee of Shanghai (Grant Nos.08DZ1203005 and 07DZ22027)
文摘On the basis of the new type Boussinesq equations (Madsen et al., 2002), a set of equations explicitly including the effects of currents on waves are derived. A numerical implementation of the present equations in one dimension is described. The numerical model is tested for wave propagation in a wave flume of uniform depth with current present. The present numerical results are compared with those of other researchers. It is validated that the present numerical model can reasonably reflect the nonlinear influences of currents on waves. Moreover, the effects of inputting different incident boundary conditions on the calculated results are studied.
文摘The anti-periodic traveling wave solutions to a forced two-dimensional generalized KdV-Burgers equation are studied. Some theorems concerning the boundness, existence and uniqueness of the solution to this equation are proved.
基金Project supported by the National Natural Science Foundation of China(No.11071164)the Innovation Program of Shanghai Municipal Education Commission(No.13ZZ118)+1 种基金the Shanghai Leading Academic Discipline Project(No.XTKX2012)the Innovation Fund Project for Graduate Stu-dent of Shanghai(No.JWCXSL1201)
文摘This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of planar dynamical systems are used to make a qualitative analysis to the planar dynamical system which the bounded traveling wave solutions of this equation correspond to. The shapes, existent number, and condi- tions are presented for all bounded traveling wave solutions. The bounded traveling wave solutions are obtained by the undetermined coefficients method according to their shapes, including exact expressions of bell and kink profile solitary wave solutions and approxi- mate expressions of damped oscillatory solutions. For the approximate damped oscillatory solution, using the homogenization principle, its error estimate is given by establishing the integral equation, which reflects the relation between the exact and approximate so- lutions. It can be seen that the error is infinitesimal decreasing in the exponential form.
基金the supports of startup grant from Guangzhou Universitysupported by the National Natural Science Foundation of China(Grant No.11874127)。
文摘We investigate the bound state problem in a one-dimensional flat band system with a Coulomb potential.It is found that,in the presence of a Coulomb potential of type I(with three equal diagonal elements),similarly to that in the twodimensional case,the flat band could not survive.At the same time,the flat band states are transformed into localized states with a logarithmic singularity near the center position.In addition,the wave function near the origin would collapse for an arbitrarily weak Coulomb potential.Due to the wave function collapses,the eigen-energies for a shifted Coulomb potential depend sensitively on the cut-off parameter.For a Coulomb potential of type II,there exist infinite bound states that are generated from the flat band.Furthermore,when the bound state energy is very near the flat band,the energy is inversely proportional to the natural number,e.g.,E_(n)∝1/n,n=1,2,3,...It is expected that the 1/n energy spectrum could be observed experimentally in the near future.
文摘We present solutions of the Schrodinger equation with superposition of Manning-Rosen plus inversely Mobius square plus quadratic Yukawa potentials using parametric Nikiforov Uvarov method along with an approximation to the centrifugal term. The bound state energy eigenvalues for any angular momentum quantum number <em>l</em> and the corresponding un-normalized wave functions are calculated. The mixed potential which in some particular cases gives the solutions for different potentials: the Manning-Rosen, the Mobius square, the inversely quadratic Yukawa and the Hulthén potentials along with their bound state energies are obtained.
文摘An investigation of origins of the quantum mechanical momentum operator has shown that it corresponds to the nonrelativistic momentum of classical special relativity theory rather than the relativistic one, as has been unconditionally believed in traditional relativistic quantum mechanics until now. Taking this correspondence into account, relativistic momentum and energy operators are defined. Schrödinger equations with relativistic kinematics are introduced and investigated for a free particle and a particle trapped in the deep potential well.