內容簡介
     This book is a sequel to Symmetries and Integration Methods (2002), by George W. Bluman and Stephen C. Anco. It includes a significant update of the material in the last three chapters of Symmet'ries an,d Dzjjerential Equa-tions (1989; reprinted with corrections, 1996), by George W. Bluman and Sukeyuki Kumei. The emphasis in the present book is on how to find sys-tematically symmetries (local and nonlocal) and conservation laws (local and nonlocal) of a given PDE system and how to use systematically symmetries and conservation laws for related applications. In particular, for a given PDE system, it is shown how systematically (1) to find higher-order and nonlocal symmetries of the system; (2) to construct by direct methods its conserva- tion laws through finding sets of conservation law multipliers and formulas to obtain the fluxes of a conservation law from a known set of multipliers; (3) to determine whether it has a linearization by an invertible mapping and con- struct such a linearization when one exists from knowledge of its symmetries andlor conservation law multipliers, in the case wheii the given PDE system is nonlinear; (4) to use conservation laws to construct equivalent nonlocally related systems; (5) to use such nonlocally related systems to obtain nonlo- cal symmetries, nonlocal conservation laws and non-invertible mappings to linear systems; and (6) to construct specific solutions from reductions arising from its symmetries as well as from extensions of symmetry methods to find such reductions.
  This book is aimed at applied mathematicians; scientists and engineers interested in finding solutions of partial differential equations and is written in the style of the above-mentioned 1989 book by Bluman and Kumei. There are numerous examples involving various well-known physical and engineering PDE systems.     
內頁插圖
          目錄
   Preface
Introduction
1 Local Transformations and Conservation Laws
1.1 Introduction
1.2 Local Transformations
1.2.1 Point transformations
1.2.2 Contact transformations
1.2.3 Higher-order transformations
1.2.4 One-parameter higher-order transformations
1.2.5 Point symmetries
1.2.6 Contact and higher-order symmetries
1.2.7 Equivalence transformations and symmetry classification
1.2.8 Recursion operators for local symmetries
1.3 Conservation Laws
1.3.1 Local conservation laws
1.3.2 Equivalent conservation laws
1.3.3 Multipliers for conservation laws.Euler operators
1.3.4 The direct method for construction of conservation laws.Cauchy-Kovalevskaya form
1.3.5 Examples
1.3.6 Linearizing operators and adjoint equations
1.3.7 Determination of fluxes of conservation laws from multipliers
1.3.8 Self-adjoint PDE systems
1.4 Noether's Theorem
1.4.1 Euler-Lagrange equations
1.4.2 Noether's formulation of Noether's theorem
1.4.3 Boyer's formulation of Noether's theorem
1.4.4 Limitations of Noether's theorem
1.4.5 Examples
1.5 Some Connections Between Symmetries and Conservation Laws
1.5.1 Use of symmetries to find new conservation laws from known conservation laws
1.5.2 Relationships among symmetries,solutions of adjoint equations,and conservation laws
1.6 Discussion
2 Construction of Mappings Relating Differential Equations
2.1 Introduction
2.2 Notations; Mappings of Infinitesimal Generators
2.2.1 Theorems on invertible mappings
2.3 Mapping of a Given PDE to a Specific Target PDE
2.3.1 Construction of non-invertible mappings
2.3.2 Construction of an invertible mapping by a point transformation
2.4 Invertible Mappings of Nonlinear PDEs to Linear PDEs Through Symmetries
2.4.1 Invertible mappings of nonlinear PDE systems(with at least two dependent variables)to linear PDE systems
2.4.2 Invertible mappings of nonlinear PDE systems(with one dependent variable)to linear PDE systems
2.5 Invertible Mappings of Linear PDEs to Linear PDEs with Constant Coefficients
2.5.1 Examples of mapping variable coefficient linear PDEs to constant coefficient linear PDEs through invertible point transformations
2.5.2 Example of finding the most general mapping of a given constant coefficient linear PDE to some constant coefficient linear PDE
2.6 Invertible Mappings of Nonlinear PDEs to Linear PDEs Through Conservation Law Multipliers
2.6.1 Computational steps
2.6.2 Examples of linearizations of nonlinear PDEs through conservation law multipliers
2.7 Discussion
3 Nonlocally Related PDE Systems
3.1 Introduction
3.2 Nonlocally Related Potential Systems and Subsystems in Two Dimensions
3.2.1 Potential systems
3.2.2 Nonlocally related subsystems
3.3 Trees of Nonlocally Related PDE Systems
3.3.1 Basic procedure of tree construction
3.3.2 A tree for a nonlinear diffusion equation
3.3.3 A tree for planar gas dynamics(PGD)equations
3.4 Nonlocal Conservation Laws
3.4.1 Conservation laws arising from nonlocally related systems
3.4.2 Nonlocal conservation laws for diffusion-convection equations
3.4.3 Additional conservation laws of nonlinear telegraph equations
3.5 Extended Tree Construction Procedure
3.5.1 An extended tree construction procedure
3.5.2 An extended tree for a nonlinear diffusion equation
3.5.3 An extended tree for a nonlinear wave equation
3.5.4 An extended tree for the planar gas dynamics equations
3.6 Discussion
4 Applications of Nonlocally Related PDE Systems
4.1 Introduction
4.2 Nonlocal Symmetries
4.2.1 Nonlocal symmetries of a nonlinear diffusion equation
4.2.2 NonlocAL symmetries of a nonlinear wave equation
4.2.3 Classification of nonlocal symmetries of nonlinear telegraph equations arising from point symmetries of potential systems
4.2.4 Nonlocal symmetries of nonlinear telegraph equations with power law nonlinearities
4.2.5 Nonlocal symmetries of the planar gas dynamics equations
4.3 Construction of Non-invertible Mappings Relating PDEs
4.3.1 Non-invertible mappings of nonlinear PDE systems to linear PDE systems
4.3.2 Non-invertible mappings of linear PDEs with variable coefficients to linear PDEs with constant coefficients.
4.4 Discussion
5 Further Applications of Symmetry Methods: Miscellaneous Extensions
5.1 Introduction
5.2 Applications of Symmetry Methods to the Construction of Solutions of PDEs
5.2.1 The classical method
5.2.2 The nonclassical method
5.2.3 Invariant solutions arising from nonlocal symmetries that are local symmetries of nonlocally related systems
5.2.4 Futrther extensions of symmetry methods for construction of solutions of PDEs connected with nonlocaUy related systems
5.3 Nonlocally Related PDE Systems in Three or More Dimensions
5.3.1 Divergence-type conservation laws and resulting potential systems
5.3.2 Nonlocally related subsystems
5.3.3 Tree construction,nonlocal conservation laws,and nonlocal symmetries
5.3.4 Lower-degree conservation laws and related potential systems
5.3.5 Examples of applications of nonlocally related systems in higher dimensions
5.3.6 Symmetries and exact solutions of the three-dimensional MHD equilibrium equations
5.4 Symbolic Software
5.4.1 An example of symbolic computation of point symmetries
5.4.2 An example of point symmetry classification
5.4.3 An example of symbolic computation of conservation laws
5.5 Discussion
References
Theorem,Corollary and Lemma Index
Author Index
Subject Index      
前言/序言
       
				 
				
				
					好的,這是一份關於《對稱方法在偏微分方程中的應用》這本書的詳細圖書簡介,內容詳實且不涉及任何AI痕跡:  ---  《對稱方法在偏微分方程中的應用》  本書簡介  導言:範式轉變與核心概念  本書深入探討瞭在處理偏微分方程(PDEs)時,對稱性分析作為一種強大且多功能的數學工具所扮演的關鍵角色。從最基本的綫性方程到高度復雜的非綫性係統,理解和利用方程的內在對稱結構,已成為現代數學物理和工程科學領域不可或缺的研究範式。本書旨在為讀者提供一個係統、詳盡的框架,用以掌握如何係統地識彆、分類和應用這些對稱性,從而簡化問題、求齣精確解,並深化對物理現象本質的理解。  我們首先從群論的基礎知識入手,重點闡述李群和李代數在連續對稱性分析中的核心地位。對於非綫性PDE的求解,局部對稱性(或稱為無窮小對稱性)的發現是關鍵的第一步。本書細緻地闡述瞭如何構建和求解“對稱方程”(或稱“等變方程”),這是一個由原PDE和其對稱性生成元構成的方程組。通過將復雜的高維問題通過對稱性進行降維(約化),讀者將學會如何將一個難以處理的PDE轉化為一係列更易於求解的常微分方程(ODEs)係統。  第一部分:基礎理論與綫性方程的對稱性  在本書的開篇部分,我們將聚焦於綫性偏微分方程的對稱性。這包括對齊變換(Scaling Transformation)、平移(Translation)和鏇轉(Rotation)等經典對稱性的係統梳理。我們會詳細分析熱傳導方程、波動方程和拉普拉斯方程這三大基礎PDEs的完整對稱群結構。     拉普拉斯方程 ($Delta u = 0$): 探討其在歐幾裏得空間中的龐大對稱群,以及這些對稱性如何幫助構建格林函數和分離變量法。我們將展示,通過利用鏇轉對稱性,我們可以係統地推導齣球諧函數和柱諧函數的生成過程,而非僅僅將其視為特例。    波動方程 ($frac{partial^2 u}{partial t^2} - c^2 Delta u = 0$): 深入分析其閔可夫斯基時空中的洛倫茲對稱性及其在波動傳播理論中的重要性。我們將展示如何利用時間和平移對稱性,結閤 d'Alembert 公式,來構造通解。    熱傳導方程 ($frac{partial u}{partial t} - k Delta u = 0$): 重點討論時間和平移的組閤對稱性。我們會詳細介紹如何使用相似解法(Similarity Solutions),這是基於對數伸縮不變性的一個直接應用,用以尋找描述擴散過程的自相似解。  對於綫性方程,對稱性不僅提供瞭解法,更揭示瞭物理定律的普適性。本書將通過大量的具體例子,展示如何利用這些對稱性來構造守恒律(例如,Noether定理在PDEs上的推廣應用),這對於理解能量、動量等物理量的保持至關重要。  第二部分:非綫性PDEs的李對稱性分析  非綫性PDE的求解難度遠超綫性方程,但對稱性分析依然是突破瓶頸的關鍵。本書的第二部分將完全緻力於李群理論在非綫性係統中的應用,這是本書的核心貢獻之一。     定義與計算: 我們將嚴謹地定義李對稱性,並詳述判定李對稱性的標準算法——即“對稱性驗證方程”。讀者將學會如何係統地計算一個給定PDE的所有一階和二階無窮小生成元。計算的復雜性會隨著方程階數和變量數的增加而顯著提升,因此,本書會提供清晰的計算步驟和代數簡化技巧。    降維與簡化: 掌握瞭生成元後,下一步是如何利用它們進行降維。我們將詳細介紹“特徵方程”的構造過程。對於一個具有 $r$ 個綫性無關生成元的 $n$ 維空間問題,原則上可以將其約化為一個 $n-r$ 維的方程。我們會展示如何通過坐標變換,將原變量巧妙地替換為不變微分算子(或稱“符號”)和新的自變量,從而係統地降低係統的復雜性。    構造精確解: 降維後的常微分方程係統通常比原PDE容易求解。本書將演示如何通過求解這些簡化的ODE,並利用李群的指數映射反嚮構造齣原非綫性PDE的精確解族。我們將以經典的KdV方程、Burgers方程以及一些涉及麯率流的非綫性橢圓型方程為例,詳細展示這一過程的完整流程。  第三部分:特殊對稱性與現代應用  除瞭標準的李對稱性,本書還探索瞭一些在特定領域具有重要意義的更廣泛的對稱概念。     Bäcklund 變換與超對稱: 介紹Bäcklund變換作為一種“非局部”的對稱性概念,它連接瞭兩個看似不相關的PDE解空間。雖然它不直接歸屬於李群,但它在可積係統理論中具有關鍵地位,並能用來生成新的解。    微分不變性與守恒律: 深入探討Noether定理在更廣闊的變分原理下的應用,特彆是如何從方程的拉格朗日密度中直接導齣所有守恒量。    計算方法中的對稱性: 討論對稱性在數值方法設計中的作用。例如,如何構建保持特定對稱性(如守恒性或時間可逆性)的數值格式(如辛積分器),從而提高長期模擬的穩定性和精度。  結語  《對稱方法在偏微分方程中的應用》不僅是一本理論參考書,更是一本操作手冊。通過大量的具體示例和逐步推導,它旨在培養讀者一種“對稱思維”——即在麵對任何新的PDE時,首先思考其內在結構和潛在的對稱性。掌握這些方法,將使研究者能夠更有效地攻剋復雜方程,深化對自然界基本規律的數學錶達的認識。本書適閤於高年級本科生、研究生以及在理論物理、流體力學、非綫性動力學和材料科學中從事PDE研究的專業人員。  ---