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变量分离法与变系数非线性薛定谔方程的求解探索 被引量:17
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作者 张解放 徐昌智 何宝钢 《物理学报》 SCIE EI CAS CSCD 北大核心 2004年第11期3652-3656,共5页
把变量分离法应用于 (1+1)维非线性物理模型 ,构建了色散缓变光纤变系数非线性薛定谔方程的一类新的孤子解 .作为特例 ,也得到了常系数非线性薛定谔方程的包络型孤子解 。
关键词 非线性薛定谔方程 变系数 孤子解 常系数 非线性物理 变量分离法 求解 色散缓变光纤 包络
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变系数ΔLgR烃源岩测井评价技术关键参数厘定方法及应用 被引量:19
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作者 刘超 印长海 卢双舫 《天然气地球科学》 EI CAS CSCD 北大核心 2015年第10期1925-1931,共7页
针对当前变系数ΔLgR烃源岩测井评价技术的关键参数主要通过经验确定,存在缺乏客观性、定量预测方法不足等问题,研究该技术内关键系数(k和a)的'外推性',建立利用单井资料预测关键系数的方法。基于松辽盆地白垩系主要烃源岩层的... 针对当前变系数ΔLgR烃源岩测井评价技术的关键参数主要通过经验确定,存在缺乏客观性、定量预测方法不足等问题,研究该技术内关键系数(k和a)的'外推性',建立利用单井资料预测关键系数的方法。基于松辽盆地白垩系主要烃源岩层的测井和TOC分析数据,通过对比关键系数在稳定沉积地层和断陷复杂地层的外推效果发现,后者导致的TOC误差偏大,有必要研究针对单井的k值和a值的预测方法。建立了利用单井'声波时差—电阻率'交会预测k值的方法,预测结果的可信度可达到81%以上;建立了利用烃源岩厚度、成熟度和幅度差值计算系数a的公式,预测结果的可信度超过80%。该方法对沉积稳定地层和复杂地层都适用,可比目前外推方法误差降低10%以上。 展开更多
关键词 有机碳总量 变系数 ΔLgR 测井 烃源岩 松辽盆地
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基于遗传算法的小波神经网络研究及应用 被引量:9
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作者 胡新辉 陈莉 《西北大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第2期203-207,共5页
目的为改进小波神经网络算法的缺陷。方法当网络的输出层节点的输出值与1之差或输出层节点输出值小于等于设定的阈值,使用变系数法调整输出层的误差,然后再利用遗传算法优化小波网络的参数。结果在齿轮箱故障诊断中,变系数法有效地防止... 目的为改进小波神经网络算法的缺陷。方法当网络的输出层节点的输出值与1之差或输出层节点输出值小于等于设定的阈值,使用变系数法调整输出层的误差,然后再利用遗传算法优化小波网络的参数。结果在齿轮箱故障诊断中,变系数法有效地防止了误差无法逆向传播下去,使网络失去学习能力。然而,通过遗传算法的全局优化搜索能力得到网络的最优参数,从而避免了网络陷入局部最小。结论提出的基于遗传算法的小波神经网络即提高网络的诊断精度,又加快了其收敛速度。 展开更多
关键词 小波分析 小波神经网络(WNN) 变系数法 WNNGA 遗传算法 故障分析
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关于BP算法的初步研究 被引量:5
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作者 吴新根 葛家理 《小型微型计算机系统》 CSCD 北大核心 1994年第1期42-45,共4页
本文提出了两种改进BP学习算法的方法:常系数法和变系数法,加快了网络的收敛速度,增强了BP算法的可用性与实用性。
关键词 人工 神经网络 BP算法
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High-Order Solitons and Hybrid Behavior of (3 + 1)-Dimensional Potential Yu-Toda-Sasa-Fukuyama Equation with Variable Coefficients
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作者 Xiyu Tan Xingying Li 《Journal of Applied Mathematics and Physics》 2024年第8期2738-2763,共26页
In this paper, some exact solutions of the (3 + 1)-dimensional variable-coefficient Yu-Toda-Sasa-Fukuyama equation are investigated. By using Hirota’s direct method and symbolic computation, we obtained N-soliton sol... In this paper, some exact solutions of the (3 + 1)-dimensional variable-coefficient Yu-Toda-Sasa-Fukuyama equation are investigated. By using Hirota’s direct method and symbolic computation, we obtained N-soliton solution. By using the long wave limit method, the N-order rational solution can be obtained from N-order soliton solution. Then, through the paired complexification of parameters, the lump solution is obtained from N-order rational solution. Meanwhile, we obtained a hybrid solution between 1-lump solution and N-soliton (N=1,2) by using the long wave limit method and parameter complex. Furthermore, four different sets of three-dimensional graphs of solitons, lump solutions and hybrid solutions are drawn by selecting four different sets of coefficient functions which include one set of constant coefficient function and three sets of variable coefficient functions. 展开更多
关键词 variable-coefficient YTSF Equation Hirota Bilinear Method N-SOLITON Hybrid Solution
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基于误差反馈控制的变系数城市扩张模型构建及应用 被引量:7
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作者 冯徽徽 刘慧平 《地理科学》 CSCD 北大核心 2014年第5期594-600,共7页
通过模拟结果与实际情况的误差分析,将研究区划分为4种像元类型,包括漏算误差像元(Omission Error,OE)、超算误差像元(Commission Error,CE)、正确模拟的城市像元(Urban Correct,UC)及正确模拟的非城市像元(Non-urban Correct,NU... 通过模拟结果与实际情况的误差分析,将研究区划分为4种像元类型,包括漏算误差像元(Omission Error,OE)、超算误差像元(Commission Error,CE)、正确模拟的城市像元(Urban Correct,UC)及正确模拟的非城市像元(Non-urban Correct,NUC)。利用线性规划方法,将误差反馈到城市扩张模型中,动态修正模型系数,构建基于误差反馈控制的变系数城市扩张空间布局模型反映城市扩张的内在特征,最后以北京市为例,模拟了其1997-2009年的城市扩张过程,通过与传统Logistic-CA模型的模拟结果对比,验证变系数模型的有效性与实用性。研究结果表明:传统Logistic-CA模型在2001年、2005年和2009年的模拟精度分别为73.842%、64.704%和63.953%,而基于误差反馈控制的变系数城市扩张模型的模拟精度分别为75.624%、66.537%和69.142%,较Logistic-CA回归模型提高了1.782、1.833和5.189个百分点,取得了更好的模拟效果。 展开更多
关键词 城市扩张模拟 Logistic-CA模型 误差反馈控制 变系数 北京
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变系数电报方程的紧致差分格式 被引量:6
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作者 杨文洁 姜子文 《山东师范大学学报(自然科学版)》 CAS 2019年第3期262-264,共3页
本文针对二维的变系数电报方程的初边值问题构造了一种高精度三层差分格式,时间具有二阶精度,空间具有四阶精度,最后通过数值算例验证了格式的有效性.
关键词 电报方程 紧致差分格式 变系数 截断误差
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Effects of mesoscale eddies on the internal solitary wave propagation 被引量:4
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作者 LIAO Guanghong YANG Chenghao +3 位作者 XU Xiaohua SHI Xingang YUAN Yaochu HUANG Weigen 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2012年第5期26-40,共15页
The mesoscale eddy and internal wave both are phenomena commonly observed in oceans. It is aimed to investigate how the presence of a mesoscale eddy in the ocean affects wave form deformation of the internal solitary ... The mesoscale eddy and internal wave both are phenomena commonly observed in oceans. It is aimed to investigate how the presence of a mesoscale eddy in the ocean affects wave form deformation of the internal solitary wave propagation. An ocean eddy is produced by a quasi-geostrophic model in f-plane, and the one-dimensional nonlinear variable-coefficient extended Korteweg-de Vries (eKdV) equation is used to simulate an internal solitary wave passing through the mesoscale eddy field. The results suggest that the mode structures of the linear internal wave are modified due to the presence of the mesoscale eddy field. A cyclonic eddy and an anticyclonic eddy have different influences on the background environment of the internal solitary wave propagation. The existence of a mesoscale eddy field has almost no prominent impact on the propagation of a smallamplitude internal solitary wave only based on the first mode vertical structure, but the mesoscale eddy background field exerts a considerable influence on the solitary wave propagation if considering high-mode vertical structures. Furthermore, whether an internal solitary wave first passes through anticyclonic eddy or cyclonic eddy, the deformation of wave profiles is different. Many observations of solitary internal waves in the real oceans suggest the formation of the waves. Apart from topography effect, it is shown that the mesoscale eddy background field is also a considerable factor which influences the internal solitary wave propagation and deformation. 展开更多
关键词 mesoscale eddy internal solitary wave variable-coefficient extended Korteweg-de Vries equation wave deformation
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Painlevé analysis, auto-Bäcklund transformations, bilinear forms and soliton solutions for a(2+1)-dimensional variable-coefficient modified dispersive water-wave system in fluid mechanics
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作者 Fei-Yan Liu Yi-Tian Gao 《Communications in Theoretical Physics》 SCIE CAS CSCD 2023年第2期46-55,共10页
In this paper,we investigate a(2+1)-dimensional variable-coefficient modified dispersive waterwave system in fluid mechanics.We prove the Painlevéintegrability for that system via the Painlevéanalysis.We fin... In this paper,we investigate a(2+1)-dimensional variable-coefficient modified dispersive waterwave system in fluid mechanics.We prove the Painlevéintegrability for that system via the Painlevéanalysis.We find some auto-B?cklund transformations for that system via the truncated Painlevéexpansions.Bilinear forms and N-soliton solutions are constructed,where N is a positive integer.We discuss the inelastic interactions,elastic interactions and soliton resonances for the two solitons.We also graphically demonstrate that the velocities of the solitons are affected by the variable coefficient of that system. 展开更多
关键词 fluid mechanics variable-coefficient modified dispersive water-wave system Painlevéanalysis bilinear forms soliton solutions auto-Bäcklund transformations
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Theoretical investigations on a variable-coefficient generalized forced–perturbed Korteweg–de Vries–Burgers model for a dilated artery,blood vessel or circulatory system with experimental support
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作者 Xin-Yi Gao Yong-Jiang Guo Wen-Rui Shan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2023年第11期49-55,共7页
Recent theoretical physics efforts have been focused on the probes for nonlinear pulse waves in,for example,variable-radius arteries.With respect to the nonlinear waves in an artery full of blood with certain aneurysm... Recent theoretical physics efforts have been focused on the probes for nonlinear pulse waves in,for example,variable-radius arteries.With respect to the nonlinear waves in an artery full of blood with certain aneurysm,pulses in a blood vessel,or features in a circulatory system,this paper symbolically computes out an auto-B?cklund transformation via a noncharacteristic movable singular manifold,certain families of the solitonic solutions,as well as a family of the similarity reductions for a variable-coefficient generalized forced–perturbed Korteweg–de Vries–Burgers equation.Aiming,e.g.,at the dynamical radial displacement superimposed on the original static deformation from an arterial wall,our results rely on the axial stretch of the injured artery,blood as an incompressible Newtonian fluid,radius variation along the axial direction or aneurysmal geometry,viscosity of the fluid,thickness of the artery,mass density of the membrane material,mass density of the fluid,strain energy density of the artery,shear modulus,stretch ratio,etc.We also highlight that the shock-wave structures from our solutions agree well with those dusty-plasma-experimentally reported. 展开更多
关键词 dynamics in blood-filled artery or blood vessel variable-coefficient generalized forced-perturbed Korteweg-de Vries-Burgers equation solitons with experimental support Bäcklund transformation and similarity reductions singular manifold
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Pfaffianization of the variable-coefficient Kadomtsev-Petviashvili equation* 被引量:2
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作者 张晴帆 范恩贵 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第6期1505-1509,共5页
This paper constructs more general exact solutions than N-soliton solution and Wronskian solution for variable- coefficient Kadomtsev-Petviashvili (KP) equation. By using the Hirota method and Pfaffian technique, it... This paper constructs more general exact solutions than N-soliton solution and Wronskian solution for variable- coefficient Kadomtsev-Petviashvili (KP) equation. By using the Hirota method and Pfaffian technique, it finds the Grammian determinant-type solution for the variable-coefficient KP equation (VCKP), the Wronski-type Pfaffian solution and the Gram-type Pfaffian solutions for the Pfaffianized VCKP equation. 展开更多
关键词 variable-coefficient KP equation Pfaffian technique Pfaffian solution
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Integrable Variable-coefficient Coupled Cylindrical NLS Equations and Their Explicit Solutions 被引量:2
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作者 Ting SU Guo-hua DING Jian-yin FANG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2014年第4期1017-1024,共8页
Based on the generalized dressing method, we propose integrable variable coefficient coupled cylin-drical nonlinear SchrSdinger equations and their Lax pairs. As applications, their explicit solutions and their reduct... Based on the generalized dressing method, we propose integrable variable coefficient coupled cylin-drical nonlinear SchrSdinger equations and their Lax pairs. As applications, their explicit solutions and their reductions are constructed. 展开更多
关键词 variable-coefficient coupled NLS equations the generalized dressing method INTEGRABILITY
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A Generalized Variable-Coefficient Algebraic Method Exactly Solving (3+1)-Dimensional Kadomtsev-Petviashvilli Equation 被引量:3
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作者 BAI Cheng-Lin BAI Cheng-Jie ZHAO Hong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第5X期821-826,共6页
A generalized variable-coefficient algebraic method is appfied to construct several new families of exact solutions of physical interest for (3+1)-dimensional Kadomtsev-Petviashvilli (KP) equation. Among them, th... A generalized variable-coefficient algebraic method is appfied to construct several new families of exact solutions of physical interest for (3+1)-dimensional Kadomtsev-Petviashvilli (KP) equation. Among them, the Jacobi elliptic periodic solutions exactly degenerate to the soliton solutions at a certain limit condition. Compared with the existing tanh method, the extended tanh method, the Jacobi elliptic function method, and the algebraic method, the proposed method gives new and more general solutions. 展开更多
关键词 generalized variable-coefficient algebraic method (3+1)-dimensional KP equation exact explicit solutions
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纵向过载环境下变质量欧拉梁动特性分析方法 被引量:2
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作者 邢誉峰 谢珂 潘忠文 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2013年第8期999-1003,1061,共6页
过载是火箭的真实环境.考虑纵向过载环境,根据Hamilton变分原理,得到了欧拉梁变系数横向自由振动微分方程,证明了该变系数系统存在满足刚度和质量正交条件的本征解,揭示了纵向过载环境下欧拉梁本征函数的非对称性.用本征向量叠加方法和... 过载是火箭的真实环境.考虑纵向过载环境,根据Hamilton变分原理,得到了欧拉梁变系数横向自由振动微分方程,证明了该变系数系统存在满足刚度和质量正交条件的本征解,揭示了纵向过载环境下欧拉梁本征函数的非对称性.用本征向量叠加方法和改进欧拉中点直接积分算法求解了该变系数系统的动态响应,二者结果的一致性说明该理论推导的正确性和方法的可行性. 展开更多
关键词 过载 变质量 变系数 本征向量 正交条件
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Riemann theta function periodic wave solutions for the variable-coefficient mKdV equation 被引量:1
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作者 张翼 程智龙 郝晓红 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期23-30,共8页
In this paper, a variable-coefficient modified Korteweg-de Vries (vc-mKdV) equation is considered. Bilinear forms are presented to explicitly construct periodic wave solutions based on a multidimensional Riemann the... In this paper, a variable-coefficient modified Korteweg-de Vries (vc-mKdV) equation is considered. Bilinear forms are presented to explicitly construct periodic wave solutions based on a multidimensional Riemann theta function, then the one and two periodic wave solutions are presented~ and it is also shown that the soliton solutions can be reduced from the periodic wave solutions. 展开更多
关键词 variable-coefficient mKdV equation Riemann theta function soliton solutions periodic wave solutions
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Nonsingular Positon Solutions of a Variable-Coefficient Modified KdV Equation 被引量:1
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作者 Yi Lin Chuanzhong Li Jingsong He 《Open Journal of Applied Sciences》 2013年第1期102-105,共4页
The determinant representation of three-fold Darboux transformation for a variable-coefficient modified KdV equation is displayed based on the technique used to solve Ablowitz-Kaup-Newell-Segur system. Additionally, t... The determinant representation of three-fold Darboux transformation for a variable-coefficient modified KdV equation is displayed based on the technique used to solve Ablowitz-Kaup-Newell-Segur system. Additionally, the nonsingular positon solutions of the variable-coefficient modified KdV equation are firstly discovered analytically and graphically. 展开更多
关键词 variable-coefficient KdV Equation LAX Pair DARBOUX Transformation POSITON Soliton-Positon
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The extended symmetry approach for studying the general Korteweg-de Vries-type equation 被引量:1
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作者 李志芳 阮航宇 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第4期3-10,共8页
The extended symmetry approach is used to study the general Korteweg-de Vries-type (KdV-type) equation. Several variable-coefficient equations are obtained. The solutions of these resulting equations can be construc... The extended symmetry approach is used to study the general Korteweg-de Vries-type (KdV-type) equation. Several variable-coefficient equations are obtained. The solutions of these resulting equations can be constructed by the solutions of original models if their solutions are well known, such as the standard constant coefficient KdV equation and the standard compound KdV--Burgers equation, and so on. Then any one of these variable-coefficient equations can be considered as an original model to obtain new variable-coefficient equations whose solutions can also be known by means of transformation relations between solutions of the resulting new variable-coefficient equations and the original equation. 展开更多
关键词 extended symmetry approach general Korteweg-de Vries-type (KdV-type) equation variable-coefficient equation
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一类变系数线性常微分方程的有界变差解 被引量:2
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作者 李宝麟 李林强 《西北师范大学学报(自然科学版)》 CAS 北大核心 2011年第4期1-6,共6页
利用Kurzweil广义常微分方程理论,在较弱的条件下,给出一类变系数线性常微分方程有界变差解存在唯一的充要条件及通解公式,并给出了一个应用.
关键词 变系数 线性常微分方程 LEBESGUE可积 有界变差解
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Lax Pair and Darboux Transformation for a Variable-Coefficient Fifth-Order Korteweg-de Vries Equation with Symbolic Computation 被引量:2
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作者 ZHANG Ya-Xing ZHANG Hai-Qiang +3 位作者 LI Juan XU Tao ZHANG Chun-Yi TIAN Bo 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第4期833-838,共6页
In this paper, we put our focus on a variable-coe^cient fifth-order Korteweg-de Vries (fKdV) equation, which possesses a great number of excellent properties and is of current importance in physical and engineering ... In this paper, we put our focus on a variable-coe^cient fifth-order Korteweg-de Vries (fKdV) equation, which possesses a great number of excellent properties and is of current importance in physical and engineering fields. Certain constraints are worked out, which make sure the integrability of such an equation. Under those constraints, some integrable properties are derived, such as the Lax pair and Darboux transformation. Via the Darboux transformation, which is an exercisable way to generate solutions in a recursive manner, the one- and two-solitonic solutions are presented and the relevant physical applications of these solitonic structures in some fields are also pointed out. 展开更多
关键词 variable-coefficient fifth-order Korteweg-de Vries equation Lax pair Darboux transformation solitonic solutions symbolic computation
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Wronskian and Grammian Determinant Solutions for a Variable-Coefficient Kadomtsev-Petviashvili Equation 被引量:2
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作者 YAO Zhen-Zhi ZHANG Chun-Yi +4 位作者 ZHU Hong-Wu MENG Xiang-Hua LU Xing SHAN Wen-Rui TIAN Bo 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第5期1125-1128,共4页
In this paper, we derive the bilinear form for a variable-coefficient Kadomtsev Petviashvili-typed equation. Based on the bilinear form, we obtain the Wronskian determinant solution, which is proved to be indeed an ex... In this paper, we derive the bilinear form for a variable-coefficient Kadomtsev Petviashvili-typed equation. Based on the bilinear form, we obtain the Wronskian determinant solution, which is proved to be indeed an exact solution of this equation through the Wronskian technique. In addition, we testify that this equation can be reduced to a Jacobi identity by considering its solution as a Grammian determinant by means of Pfaffian derivative formulae. 展开更多
关键词 variable-coefficient Kadomtsev-Petviashvili equation Wronskian determinant Grammian deter-minant PFAFFIAN Jacobi identity
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