The lattice Boltzmann method (LBM) and the immersed boundary method (IBM) are alternative, com- putational techniques for solving complex fluid dynamics systems, and can take the place of the Navier-Stokes(N- S)...The lattice Boltzmann method (LBM) and the immersed boundary method (IBM) are alternative, com- putational techniques for solving complex fluid dynamics systems, and can take the place of the Navier-Stokes(N- S) equation. This paper proposes a novel immersed boundary-lattice Boltzmann method (IB-LBM) based on the feedback law. The method uses the immersed boundary concept in the LBM framework to capture the coupling between a body with complex geometry and a uniform fluid, Then, the flows around a stationary circular cylinder and two circular cylinders in a side by side arrangement are simulated by using the method. Results are agreed well with the benchmark data, so, the capability of the method for complex geometry is demonstrated. Different from the conventional IB-LBM, which uses the Hook's law or the direct forcing method to compute the interae- tion force, the method uses the feedback law--the feedback of velocity field and displacement information to calculate the force, thus ensuring the method has advantages of easy implementation and full parallelism.展开更多
In order to enhance geological body boundary visual effects in images and improve interpretation accuracy using gravity and magnetic field data, we propose an improved small sub-domain filtering method to enhance grav...In order to enhance geological body boundary visual effects in images and improve interpretation accuracy using gravity and magnetic field data, we propose an improved small sub-domain filtering method to enhance gravity anomalies and gravity gradient tensors. We discuss the effect of Gaussian white noise on the improved small sub-domain filtering method, as well as analyze the effect of window size on geological body edge recognition at different extension directions. Model experiments show that the improved small sub-domain filtering method is less affected by noise, filter window size, and geological body edge direction so it can more accurately depict geological body edges than the conventional small sub-domain filtering method. It also shows that deeply buried body edges can be well delineated through increasing the filter window size. In application, the enhanced gravity anomalies and calculated gravity gradient tensors of the Hulin basin show that the improved small sub-domain filtering can recognize more horizontal fault locations than the conventional method.展开更多
A rotational parameter Rθ has been introduced to complex wavelet transform (CWT). The rotational CWT (RCWT) corresponds to a matrix element 〈φ|U2(θ;μ;κ)[F〉 in the context of quantum mechanics, where U2(...A rotational parameter Rθ has been introduced to complex wavelet transform (CWT). The rotational CWT (RCWT) corresponds to a matrix element 〈φ|U2(θ;μ;κ)[F〉 in the context of quantum mechanics, where U2(θ;μ;κ) is a two-mode rotational displacing-squeezing operator in the 〈η| representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac's representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.展开更多
Recently, we found that side lobes of wavelets have a large impact on the identification of thin sand reservoirs when studying some gas fields in a basin in Northwest China. Reflections from the top of the H Formation...Recently, we found that side lobes of wavelets have a large impact on the identification of thin sand reservoirs when studying some gas fields in a basin in Northwest China. Reflections from the top of the H Formation, in which there are gas-bearing thin sand bodies, have the main wavelet lobe between two weak peak side lobes. The lower one always mixes with another peak reflected from the top of a thin sand reservoir. That makes it difficult to identify the sand reservoir. In order to solve this, many forward models were set up using typical well logs. 2D synthetic profiles were produced using Ricker wavelets to study the relationships between the effects of wavelet side lobes and thin sand position and frequency and between amplitude and the thin sand body. We developed the following conclusions: First, it is easier to identify thin sands in a shallower position. Second, a good way to tell sand body reflections from side lobes is by comparing profiles with different frequency windows. Third, it is helpful and effective to describe sand extent using amplitude attributes.展开更多
We introduce the bipartite entangled states to present a quantum mechanical version of complex wavelet transform. Using the technique of integral within an ordered product of operators we show that the complex wavelet...We introduce the bipartite entangled states to present a quantum mechanical version of complex wavelet transform. Using the technique of integral within an ordered product of operators we show that the complex wavelet transform can be studied in terms of various quantum state vectors in two-mode Fock space. In this way the creterion for mother wavelet can be examined quantum-mechanically and therefore more deeply.展开更多
Starting from the optical fractional Fourier transform (FFT) and using the technique of integration withinan ordered product of operators we establish a formalism of FFT for quantum mechanical wave functions. In doing...Starting from the optical fractional Fourier transform (FFT) and using the technique of integration withinan ordered product of operators we establish a formalism of FFT for quantum mechanical wave functions. In doing so, theessence of FFT can be seen more clearly, and the FFT of some wave functions can be derived more directly and concisely.We also point out that different FFT integral kernels correspond to different quantum mechanical representations. Theyare generalized FFT. The relationship between the FFT and the rotated Wigner operator is studied by virtue of theWeyl ordered form of the Wigner operator.展开更多
According to concrete age, the dynamic stress intensity factors of bond interface crack of concrete-rock was calculated. Result shows that the propagation of concreteinterface crack is mainly caused by tensile stress ...According to concrete age, the dynamic stress intensity factors of bond interface crack of concrete-rock was calculated. Result shows that the propagation of concreteinterface crack is mainly caused by tensile stress and shear stress for stress wave reflection. With the growth of concrete age, interface crack fracture toughness increases, and itscapacity of resisting blasting load strengthens. Therefore, blasting vibration should bestrictly controlled for fresh concrete.展开更多
Addressed is the calculation of millimeter wave attenuation on coplanar waveguide(CPW). A novel conformal wavelet finite-difference time-domain(CWFDTD) algorithm is proposed with emphasis on its application in calcula...Addressed is the calculation of millimeter wave attenuation on coplanar waveguide(CPW). A novel conformal wavelet finite-difference time-domain(CWFDTD) algorithm is proposed with emphasis on its application in calculation of millimeter wave attenuation on CPW, which is the combination of conformal algorithm dealing with the deformed cell with Wavelet-FDTD using multi-resolution analysis(MRA). Derived is the difference formulation for multi-resolution time domain(MRTD) based on Daubechies wavelets, and also given is the stability conditions for wavelet-FDTD algorithm. To validate its accuracy and efficiency, this novel method is applied to calculate the millimeter wave attenuation on lithium niobate CPW. Numerical results demonstrate that this new CWFDTD algorithm has the same accuracy with the conformal finite-difference time-domain(CFDTD) and conformal finite-difference time-domain based on alternating-direction implicit method(ADI-CFDTD), but saves computational time and computer memory.展开更多
Acousto ultrasonic input output characteristics for transmitting and receiving contact type transducers coupled to a Timoshenko beam waveguide are considered. By means of a multiple integral transform method and co...Acousto ultrasonic input output characteristics for transmitting and receiving contact type transducers coupled to a Timoshenko beam waveguide are considered. By means of a multiple integral transform method and contour integration technique, the spectral response of the normal contact force between the receiving transducer and the wave guide, due to an arbitrary input pulse excited by the transmitting transducer, is expressed as a form of explicitly physical interpretations. Time histories of the response are then obtained through the inversion of the spectra by a fast Fourier transform (FFT) method. Finally, some numerical results are presented in diagrams, from which the effects on the mass of the receiver, the distance between the two transducers, and the input pulse width on the output are discussed. From the numerical calculation and the nature of the whole analysis it is shown that the analytical method presented in this paper is not only effective but also extendible to the more general cases.展开更多
Elliptic equation is taken as an ansatz and applied to solve nonlinear wave equations directly. More kinds of solutions are directly obtained, such as rational solutions, solitary wave solutions, periodic wave solutio...Elliptic equation is taken as an ansatz and applied to solve nonlinear wave equations directly. More kinds of solutions are directly obtained, such as rational solutions, solitary wave solutions, periodic wave solutions and so on.It is shown that this method is more powerful in giving more kinds of solutions, so it can be taken as a generalized method.展开更多
We investigate the effects of extension and overlap of wavefunctions on the dispersion relations of plasmon modes in symmetric double-quantum-well structures. We compare the approximate results in two-dimensional laye...We investigate the effects of extension and overlap of wavefunctions on the dispersion relations of plasmon modes in symmetric double-quantum-well structures. We compare the approximate results in two-dimensional layer-gas (2DLG) model with the exact ones where the extension and overlap of the wavefunctions are included. Our numerical results show that the 2DLG model is a good approximation only in the wide barrier case in the long wavelength limit. When the barrier is thin, the extension and overlap of the wavefunctions cannot be neglected. We also show that the long wavelength gap of the inter-subband mode is proportional to the energy difference between the ground and the first excited energy levels.展开更多
In 3-mode Fock space we find a new tripartite entangled state |α,γ 】 λ,which make up a new quantum mechanical representation. The state |α,γ 】 λ, can be generated byusing the setup composing of a beam splitter...In 3-mode Fock space we find a new tripartite entangled state |α,γ 】 λ,which make up a new quantum mechanical representation. The state |α,γ 】 λ, can be generated byusing the setup composing of a beam splitter and a parametric down-conversion amplifier. Applicationof the state is briefly discussed.展开更多
Kinetic Alfven Wave (KAW) is one of the low-frequency electromagnetic fluctuations that are identified extensively in space plasmas by in situ observations of satellites and has been an interesting topic for discussio...Kinetic Alfven Wave (KAW) is one of the low-frequency electromagnetic fluctuations that are identified extensively in space plasmas by in situ observations of satellites and has been an interesting topic for discussion widely in the fields of laboratory, space, and astrophysical plasmas because of its potential importance in plasma particle energization. Some satellite observations show that the number density ratio of the oxygen ions to the ambient plasma is 30% similar to 50%, sometimes, even as high as 80%. In this paper, effects of heavy ion species on KAWs are studied in a low-beta plasma. The results show that heavy ions not only considerably reduce the propagation speed of KAWs, but also remarkably influence the parallel component of perturbed electric field of KAWs (to the ambient magnetic field). The ratio of parallel to perpendicular components of perturbed field decreases (or increases) with the heavy ion abundance for KAWs dominated by the electron inertial length (or by ion acoustic gyroradius). In particular, the resonant condition of KAWs with thermal electrons is modified by the heavy ion species.展开更多
A chemical process may involve multiple adiabatic electronic states, and non-adiabatic couplings play an important role in the reaction mechanism. In this work, the effect of non-adiabatic couplings in the H+MgH;→Mg;...A chemical process may involve multiple adiabatic electronic states, and non-adiabatic couplings play an important role in the reaction mechanism. In this work, the effect of non-adiabatic couplings in the H+MgH;→Mg;+H;reaction are studied using the time-dependent wave packet method and trajectory surface hopping method. The calculated results show that the reaction follows a direct abstraction process when the non-adiabatic couplings are neglected. However, when non-adiabatic couplings are included in the calculations, a longlived excited state complex(MgH_(2)+)*can be formed during the reaction. These direct and complex-forming reaction pathways are revealed by trajectory surface hopping calculations.The non-adiabatic couplings induced complex-forming mechanism not only increases the reactivity but also has significant effect on the product vibrational state distribution.展开更多
By means of an extended variational approach,we study dynamics for gap solitons in a repulsive interactionBose-Einstein condensate under both a harmonic and an optical lattice confinement.The simplified analytic theor...By means of an extended variational approach,we study dynamics for gap solitons in a repulsive interactionBose-Einstein condensate under both a harmonic and an optical lattice confinement.The simplified analytic theorygives the critical strength ratio of harmonic to optical lattice necessary to support multiple stable lattice sites for thecondensate.Moreover,we use numerical experiments to guide and manipulate the gap solitons to an arbitrary positionvia a time-dependent potential.All predictions of the extended variational approach are reasonably close to results ofthe simulations.In particular,the variational model helps capture the composition relationship between the variationsof chirp and amplitude.展开更多
Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over...Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.展开更多
A transformation is introduced on the basis of the projective Riccati equations, and it is applied as an intermediate in expansion method to solve nonlinear Schrǒdinger (NLS) equation and coupled NLS equations. Manyk...A transformation is introduced on the basis of the projective Riccati equations, and it is applied as an intermediate in expansion method to solve nonlinear Schrǒdinger (NLS) equation and coupled NLS equations. Manykinds of envelope travelling wave solutions including envelope solitary wave solution are obtained, in which some arefound for the first time.展开更多
基金Supported by the Aeronautical Science Foundation of China(20111453012)the National Defense Pre-Research Foundation of China(9140A13040111HK0329)~~
文摘The lattice Boltzmann method (LBM) and the immersed boundary method (IBM) are alternative, com- putational techniques for solving complex fluid dynamics systems, and can take the place of the Navier-Stokes(N- S) equation. This paper proposes a novel immersed boundary-lattice Boltzmann method (IB-LBM) based on the feedback law. The method uses the immersed boundary concept in the LBM framework to capture the coupling between a body with complex geometry and a uniform fluid, Then, the flows around a stationary circular cylinder and two circular cylinders in a side by side arrangement are simulated by using the method. Results are agreed well with the benchmark data, so, the capability of the method for complex geometry is demonstrated. Different from the conventional IB-LBM, which uses the Hook's law or the direct forcing method to compute the interae- tion force, the method uses the feedback law--the feedback of velocity field and displacement information to calculate the force, thus ensuring the method has advantages of easy implementation and full parallelism.
基金supported by the Scientific Research Starting Foundation of HoHai University, China (No. 2084/40801136)the Fundamental Research Funds for the Central Universities (No.2009B12514).
文摘In order to enhance geological body boundary visual effects in images and improve interpretation accuracy using gravity and magnetic field data, we propose an improved small sub-domain filtering method to enhance gravity anomalies and gravity gradient tensors. We discuss the effect of Gaussian white noise on the improved small sub-domain filtering method, as well as analyze the effect of window size on geological body edge recognition at different extension directions. Model experiments show that the improved small sub-domain filtering method is less affected by noise, filter window size, and geological body edge direction so it can more accurately depict geological body edges than the conventional small sub-domain filtering method. It also shows that deeply buried body edges can be well delineated through increasing the filter window size. In application, the enhanced gravity anomalies and calculated gravity gradient tensors of the Hulin basin show that the improved small sub-domain filtering can recognize more horizontal fault locations than the conventional method.
基金National Natural Science Foundation of China under Grant No.10647133the Research Foundation of the Education Department of Jiangxi Province under Grant No.[2007]22
文摘A rotational parameter Rθ has been introduced to complex wavelet transform (CWT). The rotational CWT (RCWT) corresponds to a matrix element 〈φ|U2(θ;μ;κ)[F〉 in the context of quantum mechanics, where U2(θ;μ;κ) is a two-mode rotational displacing-squeezing operator in the 〈η| representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac's representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.
文摘Recently, we found that side lobes of wavelets have a large impact on the identification of thin sand reservoirs when studying some gas fields in a basin in Northwest China. Reflections from the top of the H Formation, in which there are gas-bearing thin sand bodies, have the main wavelet lobe between two weak peak side lobes. The lower one always mixes with another peak reflected from the top of a thin sand reservoir. That makes it difficult to identify the sand reservoir. In order to solve this, many forward models were set up using typical well logs. 2D synthetic profiles were produced using Ricker wavelets to study the relationships between the effects of wavelet side lobes and thin sand position and frequency and between amplitude and the thin sand body. We developed the following conclusions: First, it is easier to identify thin sands in a shallower position. Second, a good way to tell sand body reflections from side lobes is by comparing profiles with different frequency windows. Third, it is helpful and effective to describe sand extent using amplitude attributes.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475056 and the Ph. D Tutoring Foundation of the Ministry of Education
文摘We introduce the bipartite entangled states to present a quantum mechanical version of complex wavelet transform. Using the technique of integral within an ordered product of operators we show that the complex wavelet transform can be studied in terms of various quantum state vectors in two-mode Fock space. In this way the creterion for mother wavelet can be examined quantum-mechanically and therefore more deeply.
文摘Starting from the optical fractional Fourier transform (FFT) and using the technique of integration withinan ordered product of operators we establish a formalism of FFT for quantum mechanical wave functions. In doing so, theessence of FFT can be seen more clearly, and the FFT of some wave functions can be derived more directly and concisely.We also point out that different FFT integral kernels correspond to different quantum mechanical representations. Theyare generalized FFT. The relationship between the FFT and the rotated Wigner operator is studied by virtue of theWeyl ordered form of the Wigner operator.
基金Supported by the National Natural Science Foundation of China(50774056,50779050)Scientific Research Fund of Wuhan University of Science and Technology(080068,2008XY19)
文摘According to concrete age, the dynamic stress intensity factors of bond interface crack of concrete-rock was calculated. Result shows that the propagation of concreteinterface crack is mainly caused by tensile stress and shear stress for stress wave reflection. With the growth of concrete age, interface crack fracture toughness increases, and itscapacity of resisting blasting load strengthens. Therefore, blasting vibration should bestrictly controlled for fresh concrete.
基金Natural Science Foundation of Hubei Province(2005ABA311)
文摘Addressed is the calculation of millimeter wave attenuation on coplanar waveguide(CPW). A novel conformal wavelet finite-difference time-domain(CWFDTD) algorithm is proposed with emphasis on its application in calculation of millimeter wave attenuation on CPW, which is the combination of conformal algorithm dealing with the deformed cell with Wavelet-FDTD using multi-resolution analysis(MRA). Derived is the difference formulation for multi-resolution time domain(MRTD) based on Daubechies wavelets, and also given is the stability conditions for wavelet-FDTD algorithm. To validate its accuracy and efficiency, this novel method is applied to calculate the millimeter wave attenuation on lithium niobate CPW. Numerical results demonstrate that this new CWFDTD algorithm has the same accuracy with the conformal finite-difference time-domain(CFDTD) and conformal finite-difference time-domain based on alternating-direction implicit method(ADI-CFDTD), but saves computational time and computer memory.
文摘Acousto ultrasonic input output characteristics for transmitting and receiving contact type transducers coupled to a Timoshenko beam waveguide are considered. By means of a multiple integral transform method and contour integration technique, the spectral response of the normal contact force between the receiving transducer and the wave guide, due to an arbitrary input pulse excited by the transmitting transducer, is expressed as a form of explicitly physical interpretations. Time histories of the response are then obtained through the inversion of the spectra by a fast Fourier transform (FFT) method. Finally, some numerical results are presented in diagrams, from which the effects on the mass of the receiver, the distance between the two transducers, and the input pulse width on the output are discussed. From the numerical calculation and the nature of the whole analysis it is shown that the analytical method presented in this paper is not only effective but also extendible to the more general cases.
文摘Elliptic equation is taken as an ansatz and applied to solve nonlinear wave equations directly. More kinds of solutions are directly obtained, such as rational solutions, solitary wave solutions, periodic wave solutions and so on.It is shown that this method is more powerful in giving more kinds of solutions, so it can be taken as a generalized method.
文摘We investigate the effects of extension and overlap of wavefunctions on the dispersion relations of plasmon modes in symmetric double-quantum-well structures. We compare the approximate results in two-dimensional layer-gas (2DLG) model with the exact ones where the extension and overlap of the wavefunctions are included. Our numerical results show that the 2DLG model is a good approximation only in the wide barrier case in the long wavelength limit. When the barrier is thin, the extension and overlap of the wavefunctions cannot be neglected. We also show that the long wavelength gap of the inter-subband mode is proportional to the energy difference between the ground and the first excited energy levels.
文摘In 3-mode Fock space we find a new tripartite entangled state |α,γ 】 λ,which make up a new quantum mechanical representation. The state |α,γ 】 λ, can be generated byusing the setup composing of a beam splitter and a parametric down-conversion amplifier. Applicationof the state is briefly discussed.
文摘Kinetic Alfven Wave (KAW) is one of the low-frequency electromagnetic fluctuations that are identified extensively in space plasmas by in situ observations of satellites and has been an interesting topic for discussion widely in the fields of laboratory, space, and astrophysical plasmas because of its potential importance in plasma particle energization. Some satellite observations show that the number density ratio of the oxygen ions to the ambient plasma is 30% similar to 50%, sometimes, even as high as 80%. In this paper, effects of heavy ion species on KAWs are studied in a low-beta plasma. The results show that heavy ions not only considerably reduce the propagation speed of KAWs, but also remarkably influence the parallel component of perturbed electric field of KAWs (to the ambient magnetic field). The ratio of parallel to perpendicular components of perturbed field decreases (or increases) with the heavy ion abundance for KAWs dominated by the electron inertial length (or by ion acoustic gyroradius). In particular, the resonant condition of KAWs with thermal electrons is modified by the heavy ion species.
基金supported by the National Natural Science Foundation of China(No.11774043)。
文摘A chemical process may involve multiple adiabatic electronic states, and non-adiabatic couplings play an important role in the reaction mechanism. In this work, the effect of non-adiabatic couplings in the H+MgH;→Mg;+H;reaction are studied using the time-dependent wave packet method and trajectory surface hopping method. The calculated results show that the reaction follows a direct abstraction process when the non-adiabatic couplings are neglected. However, when non-adiabatic couplings are included in the calculations, a longlived excited state complex(MgH_(2)+)*can be formed during the reaction. These direct and complex-forming reaction pathways are revealed by trajectory surface hopping calculations.The non-adiabatic couplings induced complex-forming mechanism not only increases the reactivity but also has significant effect on the product vibrational state distribution.
基金Supported by the National Natural Science Foundation of China under Grant No. 10672147the Natural Science Foundation of Zhejiang Province, China under Grant Nos. Y605312, Y1080959the Department of Education Foundation of Zhejiang Province under Grant No. 20030704
文摘By means of an extended variational approach,we study dynamics for gap solitons in a repulsive interactionBose-Einstein condensate under both a harmonic and an optical lattice confinement.The simplified analytic theorygives the critical strength ratio of harmonic to optical lattice necessary to support multiple stable lattice sites for thecondensate.Moreover,we use numerical experiments to guide and manipulate the gap solitons to an arbitrary positionvia a time-dependent potential.All predictions of the extended variational approach are reasonably close to results ofthe simulations.In particular,the variational model helps capture the composition relationship between the variationsof chirp and amplitude.
文摘Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.
基金The project supported by National Natural Science Foundation of China under Grant Nos.40045016 and 40175016
文摘A transformation is introduced on the basis of the projective Riccati equations, and it is applied as an intermediate in expansion method to solve nonlinear Schrǒdinger (NLS) equation and coupled NLS equations. Manykinds of envelope travelling wave solutions including envelope solitary wave solution are obtained, in which some arefound for the first time.