有限时滞Lienard方程Hopf分支的数值逼近

研究了一类有限时滞的Lienard方程Hopf分支的数值逼近问题．首先，以滞量为参数，应用Cooke和JHale的方法，得到Hopf分支存在的条件；然后，利用欧拉方法将得到的差分方程表示为映射，利用离散动力系统的分支理论，给出了差分方程Hopf分支存在的奈件和连续系统与其数值逼近间的关系．证明了当该系统在r=ro产生Hopf分支时，其数值逼近也在相应的参数rh处具有Hopf分支，并且忙rb=ro＋o（h）．     

一阶中立型Logistic微分方程的Hopf分支

研究了一类具有两个离散时滞的中立型Logistic微分方程dy(t)/dt=ry(t)[(1-y(t-τ1)/k) cd/dt(1-y(t-τ2)/k)]的Hopf分支，其中τ1，τ2不相等且不同时为零．首先给出零解局部稳定的定理和超越方程零点分布的一般理论，再选择一个时滞为分支参数来分析其特征方程，证明Hopf分支的存在性，并找到了分支点．     

向日葵方程的Hopf分支

以b为参数，讨论了向日葵方程ae (a/r)a^. (b/r)sina(t-r)=0的Hopf分支，给出了存在Hopf分支的条件及稳定性性质．     

具有时滞的捕食-食饵系统的Hopf分支分析

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。     

具二时滞三种群捕食-食饵系统的稳定性和Hopf分支

主要研究一类具二时滞三种群捕食-食饵系统的稳定性和Hopf分支．以时滞为参数,证明其在正平衡点的局部稳定性和Hopf分支的存在性,并利用数值模拟验证了所得结论．     

Marchuk模型的稳定性及其Hopf分支

文章是以时滞!为参数,利用分析Marchuk模型的特征方程根,获得了在正平衡点绝对稳定性的代数判据,同时得到模型存在Hopf分支的条件。     

一类时滞系统的全局Hopf分支的存在性

以时滞为参数，研究了一类时滞捕食一食饵系统的正平衡点的稳定性及局部Hopf分支的存在性．应用一般泛函微分方程的全局Hopf分支定理，讨论了该系统的全局Hopf分支的存在性．     

一类具有时滞的Logistic模型的Hopf分支

本文对一类具有连续时滞与离散时滞的Logistic模型进行分析，得到了该模型全时滞稳定的充分必要条件，同时，还给出了Hopf分支存在的条件．     

累进所得税的乘数一加速模型的Hopf分支与极限环存在的参数区间

对一个所得税的乘数-加速模型进行定性分析．给出了累进所得税和比例所得税的模型的正平衡点是稳定的条件，累进所得税的模型存在Hopf分支的条件以及用Excel给出了关于累进度参数保证极限环存在的区间。     

一类时滞竞争捕食系统模型的Hopf分支

研究了一类两捕食者一食饵的时滞竞争系统模型的Hopf分支。以食饵的成熟时滞为分支参数,通过分析系统模型相应特征方程根的分布,得到系统模型局部渐近稳定和产生局部Hopf分支的充分条件。最后,利用仿真实例对所得结果进行了验证。     

汉字倒说

汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。     

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,     

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?     

钱生钱!

我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了     

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.     

Inequalities for inscribed simplexes

The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex.     

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.     

微薄的薪水,高尚的情操

现在,我们可以没有面包,没有钱,没有房子,没有车子……但我们唯独不能丢失的是高尚的情操,笃定的信念,还有,满满的希望!     

Virtual reality approach for 3D large model browsing on web site

Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator＇s Garden. Translating building data to the Virtual Reality Modeling Language （VRML） is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching.