期刊文献+
共找到921篇文章
< 1 2 47 >
每页显示 20 50 100
Variable Separation and Exact Solutions for the Kadomtsev-Petviashvili Equation 被引量:1
1
作者 Lili Song Yadong Shang 《Advances in Pure Mathematics》 2015年第3期121-126,共6页
In the paper, we will discuss the Kadomtsev-Petviashvili Equation which is used to model shallow-water waves with weakly non-linear restoring forces and is also used to model waves in ferromagnetic media by employing ... In the paper, we will discuss the Kadomtsev-Petviashvili Equation which is used to model shallow-water waves with weakly non-linear restoring forces and is also used to model waves in ferromagnetic media by employing the method of variable separation. Abundant exact solutions including global smooth solutions and local blow up solutions are obtained. These solutions would contribute to studying the behavior and blow up properties of the solution of the Kadomtsev-Petviashvili Equation. 展开更多
关键词 Kadomtsev-Petviashvili Equation Method of variable separation Global Smooth SOLUTION Local BLOW up SOLUTION
下载PDF
A Variable Separation Approach to Solve the Integrable and Nonintegrable Models:Coherent Structures of the (2 + 1)-Dimensional KdV Eqnation 被引量:8
2
作者 TANG Xiao-Yan LOU Sen-Yue 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第7期1-8,共8页
We study the localized coherent structures ofa generally nonintegrable (2+ 1 )-dimensional KdV equation via a variable separation approach. In a special integrable case, the entrance of some arbitrary functions leads ... We study the localized coherent structures ofa generally nonintegrable (2+ 1 )-dimensional KdV equation via a variable separation approach. In a special integrable case, the entrance of some arbitrary functions leads to abundant coherent structures. However, in the general nonintegrable case, an additional condition has to be introduced for these arbitrary functions. Although the additional condition has been introduced into the solutions of the nonintegrable KdV equation, there still exist many interesting solitary wave structures. Especially, the nonintegrable KdV equation possesses the breather-like localized excitations, and the similar static ring soliton solutions as in the integrable case. Furthermor,in the integrable case, the interaction between two travelling ring solitons is elastic, while in the nonintegrable case we cannot find even the single travelling ring soliton solution. 展开更多
关键词 variable separation approach INTEGRABLE and nonintegrable models (2%PLUS%1)-dimensional SOLITONS
下载PDF
Separate-Type Estimators for Estimating Population Ratio in Post-Stratified Sampling Using Variable Transformation
3
作者 Aloy Chijioke Onyeka Chinyeaka Hostensia Izunobi Iheanyi Sylvester Iwueze 《Open Journal of Statistics》 2015年第1期27-34,共8页
The study proposes, along the line of [1], six separate-type estimators for estimating the population ratio of two variables in post-stratified sampling, using variable transformation. Properties of the proposed estim... The study proposes, along the line of [1], six separate-type estimators for estimating the population ratio of two variables in post-stratified sampling, using variable transformation. Properties of the proposed estimators were obtained up to first order approximations, both for achieved sample configurations (conditional argument) and over repeated samples of fixed size n (unconditional argument). Efficiency conditions, under which the proposed separate-type estimators would perform better than the associated customary separate-type estimators in terms of having smaller mean squared errors, were obtained. Furthermore, conditions under which some of the proposed separate-type estimators would perform better than other proposed separate-type estimators were also obtained. The optimum estimators among the proposed separate-type estimators were obtained and an empirical illustration confirmed the theoretical results. 展开更多
关键词 variable Transformation Separate-Type ESTIMATOR OPTIMUM ESTIMATORS Ratio Product and Regression-Type ESTIMATORS Mean Squared Error
下载PDF
隧道拱顶渗漏稳态渗流场的解析研究
4
作者 余俊 李东凯 《浙江大学学报(工学版)》 EI CAS CSCD 北大核心 2024年第4期838-846,共9页
针对隧道运营中发生拱顶渗漏且无泥沙涌入的稳态渗流情况,结合保角变换法和分离变量法推导出隧道拱顶渗漏稳态渗流场的显式解析解.应用PLAXIS有限元软件建立数值模型,从渗流场分布、衬砌水压力两方面验证所得解的正确性,通过与现有解析... 针对隧道运营中发生拱顶渗漏且无泥沙涌入的稳态渗流情况,结合保角变换法和分离变量法推导出隧道拱顶渗漏稳态渗流场的显式解析解.应用PLAXIS有限元软件建立数值模型,从渗流场分布、衬砌水压力两方面验证所得解的正确性,通过与现有解析解、数值解、试验结果的渗流量对比来验证所得解的准确性.进行参数分析,探究隧道埋深、渗漏宽度对衬砌水压力和渗流量的影响规律.结果表明,衬砌水压力在以渗漏位置为中心±60°范围内明显降低;随着隧道埋深的增大,衬砌最大水压力减小,渗流量先减小后增大,且渗流量最小值对应的隧道埋深随着地表水头的增大而增大;随着渗漏宽度的增大,衬砌最大水压力减小,渗流量增大,当渗漏宽度大于0.05 m时,渗漏宽度变化对水压力和渗流量的影响较小;在渗漏宽度较小时进行渗漏控制的效果明显. 展开更多
关键词
下载PDF
油田伴生气与CO_(2)驱采气CO_(2)回收技术研究进展
5
作者 徐赋海 付广永 +1 位作者 李乐天 王风 《山东化工》 CAS 2024年第6期118-123,共6页
油田伴生气和CO_(2)驱采气的数量巨大,且其中含有较多的CO_(2),合理回收利用其中的CO_(2)是当前油田开发和气体资源利用的重要研究领域。回收其中的CO_(2)不仅响应国家环境保护政策,而且将其合理的资源化以提高经济效益。本文以油田伴... 油田伴生气和CO_(2)驱采气的数量巨大,且其中含有较多的CO_(2),合理回收利用其中的CO_(2)是当前油田开发和气体资源利用的重要研究领域。回收其中的CO_(2)不仅响应国家环境保护政策,而且将其合理的资源化以提高经济效益。本文以油田伴生气、CO_(2)驱采气的CO_(2)回收技术为研究对象,详细介绍了当前五大类分离提纯工艺的基本原理,并对各工艺的特点以及实用性进行了综合对比与分析。另外总结分析了四类复合方法的适用性,得出变压吸附法+化学吸收法适用于较低CO_(2)浓度含量油田伴生气烃类回收和CO_(2)除杂;膜分离+变压吸附法以及膜分离+化学吸收法适用于CO_(2)浓度较高的CO_(2)驱采气的收集;化学吸收法+低温精馏法适用于制作高纯度的CO_(2)产品气。 展开更多
关键词
下载PDF
A SPECIAL METHOD OF FOURIER SERIES WHICH IS EQUAL TO THE METHOD OF SEPARATION OF VARIABLES ON BOUNDARY VALUE PROBLEM
6
作者 Yan Xianggan Wu Jike, Department of Mechanics, Peking Unirersity, Bejing 100871. China 《Acta Mechanica Solida Sinica》 SCIE EI 1997年第3期255-261,共7页
By the separation of singularity, a special Fourier series solution of the boundary value problem for plane is obtained, which can satisfy all boundary conditions and converges rapidly. II is proved that the solution ... By the separation of singularity, a special Fourier series solution of the boundary value problem for plane is obtained, which can satisfy all boundary conditions and converges rapidly. II is proved that the solution is equal to the result of separation of variables. As a result, the non-linear characteristic equations resulting from the method of separation of variables are transformed into polynomial equations that can provide a foundation for approximate computation and asymptotic analysis. 展开更多
关键词 separation of singularity series resolution method of separation of variables boundary value problem characteristic equation
下载PDF
Separation of Variable Treatment for Solving Time—Dependent Potentials
7
作者 QIANShang-Wu GUZhi-Yu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第2期149-150,共2页
We use the separation of variable treatment to treat some time-dependent systems, and point out that the condition of separability is the same as the condition of existence of invariant, and the separation of variable... We use the separation of variable treatment to treat some time-dependent systems, and point out that the condition of separability is the same as the condition of existence of invariant, and the separation of variable treatment is interrelated with the quantum-invariant method and the propagator method. We directly use the separation of variable treatment to obtain the wavefunctions of the time-dependent Coulomb potential and the time-dependent Hulthén potential. 展开更多
关键词 time-dependent system separation of variable treatment time-dependent Coulomb potential time-dependent Hulthen potential WAVEFUNCTION
下载PDF
Notes on Multi-linear Variable Separation Approach
8
作者 SHENShou-Feng ZHANGJun PANZu-Liang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第4期582-584,共3页
The multi-linear variable separation approach method is very useful to solve (2+1)-dimensional integrable systems. In this letter, we extend this method to solve (1+1)-dimensional Boiti system, (2+1)-dimensional Burge... The multi-linear variable separation approach method is very useful to solve (2+1)-dimensional integrable systems. In this letter, we extend this method to solve (1+1)-dimensional Boiti system, (2+1)-dimensional Burgers system, (2+1)-dimensional breaking soliton system, and (2+1)-dimensional Maccari system. Some new exact solutions are obtained and the universal formula obtained from many (2+1)-dimensional systems is extended or modified. 展开更多
关键词 variable separation approach (1%PLUS%1)-dimensional Boiti system (2%PLUS%1)-dimensional Burgers system (2%PLUS%1)-dimensional breaking soliton system (2%PLUS%1) -dimensional Maccari system
下载PDF
On the feasibility of variable separation method based on Hamiltonian system for plane magnetoelectroelastic solids 被引量:5
9
作者 侯国林 阿拉坦仓 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第8期2753-2758,共6页
The eigenvalue problem of an infinite-dimensional Hamiltonian operator appearing in the isotropic plane magnetoelectroelastic solids is studied. First, all the eigenvalues and their eigenfunctions in a rectangular dom... The eigenvalue problem of an infinite-dimensional Hamiltonian operator appearing in the isotropic plane magnetoelectroelastic solids is studied. First, all the eigenvalues and their eigenfunctions in a rectangular domain are solved directly. Then the completeness of the eigenfunction system is proved, which offers a theoretic guarantee of the feasibility of variable separation method based on a Hamiltonian system for isotropic plane magnetoelectroelastic solids. Finally, the general solution for the equation in the rectangular domain is obtained by using the symplectic Fourier expansion method. 展开更多
关键词 magnetoelectroelastic solid variable separation method COMPLETENESS general solution
下载PDF
Extended Group Foliation Method and Functional Separation of Variables to Nonlinear Wave Equations 被引量:9
10
作者 QU Chang-Zheng ZHANG Shun-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第4X期577-582,共6页
Generalized functional separation of variables to nonlinear evolution equations is studied in terms of the extended group foliation method, which is based on the Lie point symmetry method. The approach is applied to n... Generalized functional separation of variables to nonlinear evolution equations is studied in terms of the extended group foliation method, which is based on the Lie point symmetry method. The approach is applied to nonlinear wave equations with variable speed and external force. A complete classification for the wave equation which admits functional separable solutions is presented. Some known results can be recovered by this approach. 展开更多
关键词 symmetry group group foliation method nonlinear wave equation functional separation of variables
下载PDF
The projective Riccati equation expansion method and variable separation solutions for the nonlinear physical differential equation in physics 被引量:1
11
作者 马正义 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第7期1848-1854,共7页
Using the projective Riccati equation expansion (PREE) method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with arbitr... Using the projective Riccati equation expansion (PREE) method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with arbitrary functions for two nonlinear physical models are obtained. Based on one of the variable separation solutions and by choosing appropriate functions, new types of interactions between the multi-valued and single-valued solitons, such as a peakon-like semi-foldon and a peakon, a compacton-like semi-foldon and a compacton, are investigated. 展开更多
关键词 projective Riccati equation nonlinear physical equation variable separation solution SOLITON
下载PDF
Variable Separation for(1+1)-Dimensional Nonlinear Evolution Equations with Mixed Partial Derivatives 被引量:1
12
作者 WANG Peng-Zhou ZHANG Shun-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第10期797-802,共6页
We present basic theory of variable separation for (1 + 1)-dimensional nonlinear evolution equations withmixed partial derivatives.As an application,we classify equations u_(xt)=A(u,u_x)u_(xxx)+B(u,u_x) that admits de... We present basic theory of variable separation for (1 + 1)-dimensional nonlinear evolution equations withmixed partial derivatives.As an application,we classify equations u_(xt)=A(u,u_x)u_(xxx)+B(u,u_x) that admits derivative-dependent functional separable solutions (DDFSSs) and illustrate how to construct those DDFSSs with some examples. 展开更多
关键词 1 1-dimensional nonlinear evolution equations variable separation generalized conditional symmetry derivative-dependent functional separable solution
下载PDF
SOLID-STATE VARIABLE-TEMPERATURE NMR STUDY ON THE PHASE SEPARATION OF POLYETHER POLYURETHANE ZWITTERIONOMERS
13
作者 杨光 陈群 +2 位作者 王源身 杨昌正 邬学文 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1994年第4期302-308,共7页
Polyether-polyurethane zwitterionomers based on 4, 4'-diphenylmethane diisocyanate(MDI), methyl diethanolamine (MDEA), and polytetramethylene oxide glycol (PTMO) werestudied with variable-temperature wide-line ~1H... Polyether-polyurethane zwitterionomers based on 4, 4'-diphenylmethane diisocyanate(MDI), methyl diethanolamine (MDEA), and polytetramethylene oxide glycol (PTMO) werestudied with variable-temperature wide-line ~1H NMR. It is found that upon ionization, degree ofphase separation in the polymer system decreased at first due to the loss of hard segmentregularity, while further ionization increased the degree of phase separation through increasinghard phase cohesion and difference of polarity between hard and soft segments. 展开更多
关键词 Polyether polyurethane variable temperature Wide-line NMR Phase separation
下载PDF
Variable Separation Approach to Solve (2 + 1)-Dimensional Generalized Burgers System: Solitary Wave and Jacobi Periodic Wave Excitations
14
作者 ZHENGChun-Long 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第3期391-396,共6页
By means of the standard truncated Painlevé expansion and a variable separation approach, a general variable separation solution of the generalized Burgers system is derived. In addition to the usual localized co... By means of the standard truncated Painlevé expansion and a variable separation approach, a general variable separation solution of the generalized Burgers system is derived. In addition to the usual localized coherent soliton excitations like dromions, lumps, rings, breathers, instantons, oscillating soliton excitations, peakons, foldons, and previously revealed chaotic and fractal localized solutions, some new types of excitations — compacton and Jacobi periodic wave solutions are obtained by introducing appropriate lower dimensional piecewise smooth functions and Jacobi elliptic functions. 展开更多
关键词 generalized Burgers system variable separation approach solitary wave Jacobi periodic wave
下载PDF
New Families of Rational Form Variable Separation Solutions to(2+1)-Dimensional Dispersive Long Wave Equations
15
作者 WEN Xiao-Yong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第5期789-793,共5页
With the aid of symbolic computation system Maple, some families of new rational variable separation solutions of the (2+1)-dimensional dispersive long wave equations are constructed by means of a function transfor... With the aid of symbolic computation system Maple, some families of new rational variable separation solutions of the (2+1)-dimensional dispersive long wave equations are constructed by means of a function transformation, improved mapping approach, and variable separation approach, among which there are rational solitary wave solutions, periodic wave solutions and rational wave solutions. 展开更多
关键词 improved mapping approach variable separation method 21-dimensional dispersive long wave equations symbolic computation
下载PDF
The derivative-dependent functional variable separation for the evolution equations 被引量:3
16
作者 张顺利 楼森岳 屈长征 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第12期2765-2776,共12页
This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A(u, ux)uxx+B(u, ux, ut) which adm... This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A(u, ux)uxx+B(u, ux, ut) which admits the derivative- dependent functional separable solutions (DDFSSs). We also extend the concept of the DDFSS to cover other variable separation approaches. 展开更多
关键词 derivative-dependent functional variable separation evolution equations generalized conditional symmetry
下载PDF
Variable Separation and Derivative-Dependent Functional Separable Solutions to Generalized Nonlinear Wave Equations 被引量:3
17
作者 ZHANGShun-Li LOUSen-Yue 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第2期161-174,共14页
Using the generalized conditional symmetry approach, we obtain a number of new generalized (1+1)-dimensional nonlinear wave equations that admit derivative-dependent functional separable solutions.
关键词 variable separation nonlinear wave derivative-dependent functional separable solution
下载PDF
Functional Variable Separation for Extended Nonlinear Elliptic Equations 被引量:4
18
作者 ZHANG Shun-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第3X期385-390,共6页
This paper is devoted to the study of functional variable separation for extended nonlinear elliptic equations. By applying the functional variable separation approach to extended nonlinear elliptic equations via the ... This paper is devoted to the study of functional variable separation for extended nonlinear elliptic equations. By applying the functional variable separation approach to extended nonlinear elliptic equations via the generalized conditional symmetry, we obtain complete classification of those equations which admit functional separable solutions (FSSs) and construct some exact FSSs to the resulting equations. 展开更多
关键词 nonlinear elliptic equation functional variable separation generalized conditional symmetry
下载PDF
Analytical solution for the time-fractional heat conduction equation in spherical coordinate system by the method of variable separation 被引量:2
19
作者 Ting-Hui Ning Xiao-Yun Jiang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第6期994-1000,共7页
In this paper,using the fractional Fourier law,we obtain the fractional heat conduction equation with a time-fractional derivative in the spherical coordinate system.The method of variable separation is used to solve ... In this paper,using the fractional Fourier law,we obtain the fractional heat conduction equation with a time-fractional derivative in the spherical coordinate system.The method of variable separation is used to solve the timefractional heat conduction equation.The Caputo fractional derivative of the order 0 〈 α≤ 1 is used.The solution is presented in terms of the Mittag-Leffler functions.Numerical results are illustrated graphically for various values of fractional derivative. 展开更多
关键词 Fractional Fourier law Fractional heat conduction equation - Spherical coordinate system - The separation of variables Mittag-Leffler function
下载PDF
Variable Separation and Exact Separable Solutions for Equations of Type uxt=A(u,ux)uxx+B(u,ux) 被引量:1
20
作者 ZHANG Shun-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第6期969-978,共10页
The generalized conditional symmetry is developed to study the variable separation for equations of type uxt = A(u,ux)uxx + B(u, ux). Complete classification of those equations which admit derivative-dependent fu... The generalized conditional symmetry is developed to study the variable separation for equations of type uxt = A(u,ux)uxx + B(u, ux). Complete classification of those equations which admit derivative-dependent functional separable solutions is obtained and some of their exact separable solutions are constructed. 展开更多
关键词 nonlinear evolution equations variable separation generalized conditional symmetry
下载PDF
上一页 1 2 47 下一页 到第
使用帮助 返回顶部