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张升海 《高校应用数学学报(A辑)》1990,5(4):476-483
本文对一类非线性人口发展方程提出了Mild解和Weak解的概念,并讨论了二者之间的关系。 相似文献
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张升海 《应用数学学报(英文版)》1999,15(1):45-53
1.IntroductionandPreliminaryAgestructureinepidemicmodelshasbeenconsideredbymanyauthors,becauseoftherecoghtionthattransmissiondynamicsofcertaindiseasescouldnotbecorrectlydescribedbythetraditionalepidemicmodelswithnoagedependence.Especially,Busenbergetal.II'2]giveacompleteanalysisofafairlygeneralSISmodelwithagestructureandasteady-statetotalpopulation,showingtheekistenceofathresholdforendemicstates.In[tis],theyassumethatthepopulationhasreacheditssteadystate.Althoughitisnotilladeqilatetoassumet… 相似文献
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51.IntroductionSinceArendt[2j,Kellermann[3j,KellermannandHieder[4j,andNeubrarder[5]es-tablishedthetheoryof"integratedsemigroups",theexponentiallyboundedintegratedsemi-groupshavebeenstudiedintensivly-Butthereexistintegratedsemigroupswicharenotexpo-nentiallybounded.ItiswellknownthatmanyresultsforexponentiallyboundedintegratedsemigroupsarefoundbyusingLapIacetransformtechniques.ltshouldbenotedthatLaplacetransformtechniguesarenotavailableforintegratedsemigroupswhicharenotexponentiallybounded.It… 相似文献
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张升海 《应用数学学报(英文版)》1998,14(1):58-67
1.IntroductionRecentlymanyresultshavebeenobtainedfordistributedbilinearsystemsl3'7'8].In[3]thecontrollabilityofabilinearsystem%=Aw(t) p(t)Bw(t)wasstudied,whereAistheindnitesimalgeneratorofaCosemigroupofboundedlinearoperatorsT(t)onaBanachspaceX.B:X-- 5isaboundedlinearoperator,andpELI([0,T];R)isacontrol.TheconditionsforelementsofEtobeaccessiblefromagiveninitialstatecoweregiven.Itisclearthattheystudiedthebilinearsysteminaspecialcase.In[8]theystudiedthesysteminamorespecialcasebecausetheyass… 相似文献
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一、引言 人口发展过程的数学模型是人口发展过程分析预测和定量控制的基础。关于人口发展过程的确定性连续模型,对线性人口发展系统已有不少结果。实践证明:在人类发展的某一历史阶段中,人口发展过程可以用线性方程较准确地刻画。但是线性人口发展方程忽略了社会人口与其生存环境之间的制约关系。从长期的观点来看,研究非线性人口发展模型有着重要意义 相似文献
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