Abstract: | 在本論文中,我們將討論非線性常微分方程式之邊界值問題。在第一、二章中,我們探討下列廣義的Laplacian 邊界值問題: (g(u'))'=f(t,u(t),u'(t)), 0<t<1, u 屬於 B 其中B是一個適當的邊界條件。考慮不同的函數g與f,我們給定適當的充分條件而得到正解的存在性與唯一性。 在第三、四章中,我們考慮下列四階微分方程式之邊界 值問題: u'+rf(t,u(t))=0, 0<t<1, u 屬於 B' 其中B’是一個適當的邊界條件。利用定點定理,給定函數 的條件,我們將討論解的存在性與多重性。 In this dissertation, we will study nonlinear boundary value problems for some ordinary differential equations. In chapters 1 and 2, we study the following generalized Laplacian boundary value problems : (g(u'))'=f(t,u(t),u'(t)), 0<t<1. We establish the solution existence and uniqueness for the problem under different conditions concerning f(t,u(t),u'(t)). In chapters 3 and 4, we consider the following nonlinear fourth order boundary value problems : u'+rf(t,u(t))=0, 0<t<1. Consider different conditions concerning f(t,u(t)), we study the existence and multiplicity of solutions by using fixed point theorem. |