Periodic Solution of a Nonautonomous Diffusive Food Chain System of Three Species with Time Delays

Abstract By using the continuation theorem of coincidence degree theory,the existence of a positive periodicsolution for a nonautonomous diffusive food chain system of three species. dx_1(t)/dt=x_1(t)[r_1(t)-a_(11)(t)x_1(t)-a_(12)(t)x_2(t)]+D_1(t)[y(t)-x_1(t)], dx_2(t)/dt=x_2(t)[-r_2(t)+a_(21)(t)x_1(t-r_1)-a_(22)(t)x_2(t)-a_(23)(t)x_3(t)], dx_3(t)/dt=x_3(t)[-r_3(t)+a_(32)(t)x_2(t-r_2)-a_(33)(t)x_3(t)], dy(t)/dt=y(t)[r_4(t)-a_(44)(t)y(t)]+D_2(t)[x_1(t)-y(t)]+D_2(t)[x_1(t)-y(t)],is established,where,r_i(t),a_(ii)(t)(i=1,2,3,4),D_i(t)(i=1,2),a_(12)(t),a_(21)(t),a_(23)(t)and a_(32)(t) are all positiveperiodic continuous functions with period w>0,T_i(i=1,2)are positive constants.     

食物有限的时滞种群模型的振动性

将考虑两类具有变时滞非线性有限食物种群模型N′(t)=r(t)N(t)K-N(p(t))/K+s(t)N(σ(t)),t≥ 0和N′(t)=r(t)N(t)K-Nα(p(t))/K+s(t)Nα(σ(t)),t≥ 0,的振动性,其中α>0,ρ(t)≤t,σ(t)≤t.我们的工作推广并改进了相关文献的结果.     

一类带共轭值广义Riemann边值问题的求解

本文考虑下述边值问题Φ(t)=G_1(t)Φ~-(t) G_2(t) g(t),|t|=1.当 G_1(t)-G_2(t)或 G_1(t) G_2(t)可以亚纯延拓到单位圆内时,我们给出它的封闭形式的解,当 a(t)/[b(t) 1]或 a(t)/[b(t)-1]可以亚纯延拓到单位圆外时,求解边值问题Ψ~ (t)=a(t)Ψ~-(t) b(t) h(t),|t|=1.并纠正了文[5]的错误.     

C~n中复超球上的一类奇异积分方程的解

设α(t),g(t)和K(t,u)分别是复超球面S和S×S上满足Lipschitz连续条件,且K(t,U)/{α(u)-b(u)}是B×B上的解析函数在S上的边界值,在S上有α~2(t)±b~2(t)≠0, 则方程α(t)f(t)+2/w integral from n=s ((K(t, u)f(u)du)/((1-tu′)~n))=g(t) (*) 当且仅当g(t)使函数 (b(t)g(t))/(b(t)+a(t))+(b(t)-a(t))/(b(t)+a(t)) integral from n=s ((2K(t, u)g(u)du)/(w{b(u)-a(u)}(1-tu′)~n)) 是复超球B上的解析函数的边界值函数时,方程(*)有唯一解: f(t)=(a(t)g(t))/(a~2(t)-b~2(t))+2/(w{a(t)+b(t)}) integral from n=s ((K(t, u)g(u)du)/({b(u)-a(u)}(1-tu′)~n)) 这里b(t)=K(t, t)。     

BOUNDARY VALUE PROBLEM FOR MIXED TYPE FUNCTIONAL DIFFERENTIAL SYSTEM

1 IntroductionIn the recent years, the existence problem of BVP of second order functionaldifferential equations of the forms[p(t)i(t)]' = f(t, xf, x(t)), (1)i(t) = f(t, x(t), x(al(t)),'', x(a.(t)), i(t)), (2)x(t) = f(t, x(t), x(al(t)),'', x(U.(t)), i(t), i(n(t)),'', i(fu(t))), (3)t -- r 5 al(t),D(t) 5 t, as 0 5 t 5 T,i = 1,2,'' Ink j = 1,2,'',m, subjectto some boundary value conditions have been considered by several authors(please see [1-4],[6] and the references therein). In these pa…     

具有振动位势的二阶带强迫项、阻尼项的时滞微分方程的振动性

讨论了具有振动位势的二阶微分方程(k(t)x′(t))′+τ(t)x′(t)+p(t)x(τ(t))+q(t)x(σ(t))=e(t),利用其线性近似方程(k(t)x′(t))′+p(t)x(τ(t))+q(t)x(σ(t))=e(t)的振动性,给出了方程解振动的一个充分条件,所得结果推广了文献[Computer andMathematics with Applications,2006,51:1395-1404]的相关结果.     

C~n中复超球上的一类奇异积分方程的解

设 a(t),g(t)和 K(t,u)分别是复超球面 S 和 S×S 上满足 Lipschitz 连续条件,且K(t,u)/{a(u)-b(u)}是 B×B 上的解析函数在 S 上的边界值,在 S 上有 a~2(t)±b~2(t)≠0,则方程a(t)f(t)+2/w ∫_S (K(t,u)f(u)du)/((1-t)~n)=g(t) (1)当且仅当 g(t)使函数(b(t)g(t))/(b(t)+a(t))+(b(t)-a(t))/(b(t)+a(t)) ∫_S (2K(t,u)g(u)du)/(w{b(u)-a(u)}(1-t)~n)是复超球 B 上的解析函数的边界值函数时,方程(*)有唯一解:f(t)=(a(t)g(t))/(a~2(t)-b~2(t))+2/(w-{a(t)+b(t)}) ∫_S (K(t,u)g(u)du)/({b(u)-a(u)}(1-t)~n)这里 b(t)=K(t,t).     

具逐段常变元中立型泛函微分方程的振动性

本考虑方程(x(t)-cx(t-2[(t 1)/2]))' p(t)x(t) r(t)x(t-2[(t 1)/2])) q(t)x(t2[(t 1)/2]=0(a)和方程（x(t)-cx(t-[t]))'=a(t)x(t) b(t)x(t-[t]) p(t)x([t 1])(b)解的振动性质,得到方程（a)和（b)的解为振动解的充分条件。     

ESTIMATES ON THE SOLUTIONS OF CERTAIN HIGHER ORDER FINITE DIFFERENCE EQUATIONS

1IlltroductionLetri(t),i=1,2,-')nbepositivereal-valuedfunctionsdefinedonNo,whereNo={o,1,2,'.}.Forareal-valuedfunctiQnu(t),tENowedefinetheoperatorbbybu(t)=u(t 1)-u(t)andfori22,b'u(t)=b(A'-'u(t))andtheoperatorsLjaredefinedrecursivelybyLou(t)=u(t),Lju(t)=r…     

THE STABILITY OF RDDE (?)(t) p_1(t)x(t) q_1(t)x(t) p_2(t)x(t-r(t)) q_2(t)x(t-r(t))=0

In this paper, the author considered the stability of zero solution of linear RDDEx(t) p_1(t)x(t) q_1(t)x(t) p_2(t)x(t-r(t)) q_2(t)x(t-r(t))=0,(1)x(t) p_1(t)x(t) q_1(t)x(t) q_2(t)x(t-r(t))=0 (2)using Liapunov-Razumikhin functional and transformations and obtained some sufficient condi-tions for the stability of Eqs.(1) and (2). These results are suitable both for bounded p_i(t), q_i(t)and r(t).i =1, 2.