1998 Fiscal Year Final Research Report Summary
Theoretical and Numerical Study of the Functional Differential Equations
| Project/Area Number |
09640211
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
解析学
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
HARA Tadayuki Osaka Pref.Univ., Coll.of Eng., Professor, 工学部, 教授 (20029565)
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| Co-Investigator(Kenkyū-buntansha) |
MA Wanbiao Osaka Pref.Univ., Coll.of Eng., Assistant Prof., 工学部, 助手 (30305651)
MIYAZAKI Rinko Shizuoka Univ., Facul.of Eng., Associate Prof., 工学部, 助教授 (40244660)
SUGIE Jitsuro Shimane Univ., Facul.of Sci.& Eng., Professor, 総合理工学部, 教授 (40196720)
YONEYAMA Toshiaki Osaka Pref.Univ., Coll.of Eng., Associate Prof., 工学部, 助教授 (40175021)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Functional Differential Equation / Delay Differential Equation / Lotka Volterra Equation / Prey-Predator Model / Global Asymptotic Stability / Permanence / Ivlev Type / Holling Type |
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| Research Abstract |
Main results of our research are as follows :
1. We have improved computer softwares DDEIRK and DDE2RK which were developed in our group several years ago for computer simulation of one and two dimensional differential equations with several delays. Now we obtained new computer softwares FDEIRK and FDE2RK which are applicable to delay differential equations with integral terms. We also developed computer softwares FDE4RKP and FDE4RKT for computer simulation of soluions of higher order dimensional delay differential equations with integral terms.
2. Using these softwares FDE4RKP and FDE4RKT, we studied the behavior of solutions of delay differential equations in mathematical ecology and found some interesting properties of solutions. We succeeded to give mathematical proofs to these properties. The typical results are as follows :
(1) A neccesary and sufficient condition for the exponential asymptotic stability of the zero solution of n-dimenssional linear functional differential equations with variable coefficients.
(2) A best possible sufficient condition for the asymptotic stability of the zero solution of one dimen- sional nonlinear functional differential equations with variable coefficient.
(3) Neccesary and sufficient conditions for the global asymptotic stability and the permanence of a Lotka-Volterra type delay differential equations
(4) Sufficient conditions for the asymptotic stability of a prey-predator differential equation with delays expressed in integral terms.
(5) Neccesary and sufficient conditions for the asymptotic stability and the asymptotic constant problem of a linear functional differential equation with delays expressed in Stieltjes integral.
3. We found neccesary and sufficient conditions for the existence of a limit cycle of prey-predator differential equations without delay of Ivlev type and Holling type in mathematical ecology and succeeded to give mathematical proofs to these theorems.
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