共查询到20条相似文献，搜索用时 93 毫秒
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研究了一类具有时滞的非线性广告投资模型正平衡点的稳定性与Hopf分支.利用规范型理论和中心流形定理给出了确定分支方向及分支周期解稳定性的计算公式,并且进行了数值模拟. 相似文献
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证明了随机环境中分支过程的存在性,给出了分支随机转移函数（BRTF）的定义;利用BRTF给出了随机环境中分支过程（BPRE）的精确定义;给出了BPRE存在性的一个等价定理． 相似文献
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本文研究了一类时滞SIRS计算机网络病毒传播模型.首先确定了模型产生Hopf分支的时滞临界点.然后利用中心流形定理和规范型理论得到了确定Hopf分支的方向、稳定性和分支周期解周期大小的显性计算公式.最后,利用仿真示例验证了所得结果的正确性. 相似文献
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研究了一类食饵具有阶段结构和Holling II类功能性反应的时滞捕食系统.通过分析相关的特征方程,以捕食者的消化时滞为参数,讨论了系统正平衡点的局部稳定性和Hopf分支的存在性.进一步,利用规范型理论和中心流形定理,给出了确定Hopf分支方向和分支周期解稳定性的计算公式.最后利用仿真实例证明了理论分析结果的正确性. 相似文献
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研究一类具有时滞的阶段结构捕食-食饵系统。首先讨论正平衡点的稳定性及局部Hopf分支出现的条件;然后通过分析系统关于正平衡点的线性变分方程的特征根来研究系统在正平衡点的稳定性,应用泛函微分方程的局部Hopf分支理论给出了该模型出现周期解的条件;根据全局Hopf分支存在定理,建立了捕食-食饵系统全局Hopf分支存在性;最后通过数值模拟进行验证。 相似文献
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考虑肺部感染初始先天系统反应的动态模型,首先根据三次多项式方程根的判别式,得到了模型有正平衡点的条件,其次利用平衡点稳定性理论和中心流形定理讨论了在该条件下模型正平衡点的具体类型及稳定性,最后考虑了在平衡点处出现的鞍结点分支. 相似文献
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张庆 《河北软件职业技术学院学报》1999,(1)
代数基本定理在代数学中占有重要地位,有人曾利用复变函数论中的刘维尔定理及儒歇定理给出了该定理的证明,本文将利用复变函数论中的残数定理及最大模原理给出代数基本定理的两种证明方法。 相似文献
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利用时滞微分方程理论与Hopf分支的相关理论,对一类具有时滞的流感病毒模型进行了研究,对其惟一的正平衡点,给出了其存在Hopf分支的条件和分支方向. 相似文献
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利用时滞微分方程理论与Hopf分支的相关理论,对一类具有时滞的流感病毒模型进行了研究,对其惟一的正平衡点,给出了其存在Hopf分支的条件和分支方向. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
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正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
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《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献
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《重庆大学学报(英文版)》2014,(2)
正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof. 相似文献