一类时滞HIV模型的Hopf分支

研究了一类带时滞的HIV病毒的CD4＋细胞模型及它的平衡点的稳定性,当该模型满足一定条件时,它的平衡点稳定,当平衡点不稳定时研究了Hopf分支的存在性.     

一类具有饱和治愈率和饱和接触率的流行病动力学模型研究

主要建立了一类带有饱和治愈率和饱和接触率的SIRS传染病模型,研究得到了该模型的无病平衡点及地方病平衡点的局部稳定性,同时,借助构造Liapunov函数,给出了无病平衡点和地方病平衡点全局渐近稳定的条件.     

一类高阶差分方程系统的稳定性

研究了一类具有初值的高阶差分方程系统平衡点的稳定性问题,得到了平衡点处稳定、局部渐近稳定性、全局渐近稳定性的充分条件,讨论了正平衡点处解的振动性问题.     

具有心理因素影响的SVIR传染病模型的稳定性分析

研究了一类具有心理因素影响的传染率函数和有医疗限制的治疗函数的SVIR传染病模型。讨论了模型平衡点的存在性,计算了基本再生数,通过Hurwitz判据得到无病平衡点和地方病平衡点的局部稳定性,用构造Lyapunov函数的方法证明无病平衡点的全局稳定性,最后利用第二加性复合矩阵判断地方病平衡点的全局稳定性。     

具有时滞和非线性接触率的SIS传染病模型的稳定性分析

研究了一类具有时滞和非线性接触率的SIS传染病模型,讨论了系统平衡点的局部稳定性,根据比较定理讨论了无病平衡点的全局稳定性,并证明了地方病平衡点的一致持续性及全局稳定性。     

具有阶段结构和饱和治疗的SIS模型的动力学性态

该文研究了一类具有阶段结构的SIS传染病模型,包括：定义了模型的基本再生数：讨论了模型的无病平衡点和地方病平衡平衡点的存在性;证明了无病平衡点和地方病平衡点的局部渐近稳定性;发现了饱和治疗会引起后向分支。     

一类松籽、松鼠、幼苗的征税模型分析

运用微分方程理论,研究了一类非线性的红松种群征税模型,得到了该系统的平衡点,证明了该系统正平衡点的局部渐进稳定性和正平衡点的全局吸引域,利用Pontryagin 最大值原理给出了最优征税策略.     

一类具有潜伏期和非线性传染率的SEIR模型的全局稳定性

研究了一类具有潜伏期和一般非线性传染率函数f(S,I)的SEIR模型,得到了疾病流行的阈值R0及无病平衡点和地方病平衡点存在的条件,利用Hurwitz判据定理、Liapunov函数的方法、非线性高维动力系统理论,证明了无病平衡点和地方病平衡点的全局渐进稳定.     

一类具有阶段结构的自治传染病模型的稳定性

研究了一类具有阶段结构的传染病模型,找到了各类平衡点存在的阈值条件,并讨论了各平衡点的稳定性.     

具有Holling-II型的修改的Leslie-Gower捕食-食饵模型的定性分析

主要研究了具有Holling-II型、修改的Leslie-Gower捕食-食饵系统,对其具有一般非线性增长率和非线性密度制约的模型进行了讨论,得到了正平衡点存在、边界平衡点和正平衡点局部稳定的充分条件,通过构造Lyapunov函数,给出了平衡点处的全局稳定性分析.最后,通过数值模拟对相关的结论进行了验证.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

Sister Carrie, an Adherent of Desires

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.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.