Project/Area Number  07640179 
Research Category 
GrantinAid for Scientific Research (C)

Section  一般 
Research Field 
解析学

Research Institution  TOKYO UNIVERSITY OF FISHERIES 
Principal Investigator 
KAMIMURA Yutaka Tokyo University of Fisheries, Faculty of Fisheries, Associate Professor, 水産学部, 助教授 (50134854)

CoInvestigator(Kenkyūbuntansha) 
TSUBOI Kenji Tokyo University of Fisheries, Faculty of Fisheries, Associate Professor, 水産学部, 助教授 (50180047)

Project Fiscal Year 
1995 – 1997

Project Status 
Completed(Fiscal Year 1997)

Budget Amount *help 
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥700,000 (Direct Cost : ¥700,000)

Keywords  inverse problem / nonlinear term / boundary value problem / integral equation / convolution / 逆問題 / 非線形項 / 境界値問題 / 積分方程式 / 第一分岐 / 合成積 / 陰関数定理 / 分岐 / Abel方程式 / 固有関数 
Research Abstract 
This research was intended to solve the following problem : Problem 1 (Inverse Bifurcation Problem). Determine a nonlinear term f of the boundary value problem =u''+ [lambdaq (x)] u=f (u), 0<less than or equal>x<less than or equal>pi/2, '=d/ u' (0) =u (pi/2) =0. from its first bifurcating branch. It was also a purpose of this research to find what kind of integral equation appears when we try to solve the inverse bifurcation problem. Concerning Problem 1, two results have been established : a local existence result and a uniqueness result. In the course of our research we have realized that our method used for obtaining the above results is effective in solving similar inverse problems of determining unknown nonlinear terms appearing in boundary value problems from information on their spectral parameters. Foremost among those is the following problem : Problem 2 (DenisovLorenzi Problem). Given functions a (lambda), b (lambda) on the interval [0, A], determine a nonlinear term g, with which the (overdetermined) boundary value problem =u''=lambdag (u), 0<x<1, '=d/ u (0) =1, u' (0) =a (lambda), u (1) =b (lambda) admits a solution u for each lambda [0, A]. This problem has been discussed and an improvement of the local existence theorem in the work is given. We have also given an answer to the question : what kind of integral equations appear in establishing local existence results for Problems 1 and 2. A class of integral equations treated there would enable us to present a basic aspect of integral equations arising from nonlinear inverse problems.
