Acta mathematica scientia,Series B ›› 1995, Vol. 15 ›› Issue (1): 39-47.

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A SINGULAR OR NONSINGULAR PERTURBATION PROBLEM FOR A SECOND ORDER NONLINEAR DIFFERENTIAL EQUATION WITH TWO FREE ENDPOINTS

Wang Junyu1, Zheng Dawei2, Wang Xuekong3   

  1. 1. Department of Mathematics, Jilin University, Changchun 130023, China;
    2. Department of Mathematics, Jilin University, Changchun 130023, China;
    3. Division of Fundemental Sciences, Daqing Petroleum Institute, Anda 151400, China
  • Received:1992-06-05 Online:1995-03-25 Published:1995-03-25
  • Supported by:
    Project supported by the National Natural Science Foundation of China.

Abstract: It is proved that for ε ≥ 0 and δ ≥ 0 the two -point boundary value problem
-{y'(t)+f(t)+h(t)Ke(t,y(t))}=g(t)z(t),AtB,
z'(t)=Ke(t,y(t)):={(k(t)+ε)/y(t)}1/N,AtB,
y(A)=δ-Pz(A),y(B)=δ+Qz(B),
has a unique solution (y(t,ε,δ),z(t,ε,δ)) under certain hypotheses with the aid of the appropriate Green's function integral operator.The unique solution (ξe,ηe,ve(s)) of the free boundary problem
{(k(v)+ε)|v'|N-1v'}'+{sg(v)+f(v)}v'+h(v)=0,ε < s < η,
v|s=ε=Ae-{(k(v)+ε)|N-1v'}|s=ε=,
v|s=η=Be=Be{(k(v)+ε)|v'|N-1v'}s=η=,
is constructed utilizing the solution (y(t,ε.0),z(t,ε,0)).The fine boundary problem is shown to be a singular perturbation problem when the function k(t) possesses intervals of degeneracy

Key words: Two-point boundary value problem, free boundary problem, interval of dogeneracy

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