几类直接控制系统的绝对稳定性

本文讨论了几类直接控制系统的绝对稳定性,获得了其零解绝对稳定的判别准则,所得的结果具有简便、应用方便的优点。     

三阶直接控制系统绝对稳定的充分必要条件

本文利用Popov频率法，讨论了三阶直接控制系统　σ＝cTX零解的绝对稳定性，主要获得如下结果：1°．假设A＝（aij）3×3，Reλ（A）＜0，且cTb·trA2＋cTA2b≤0，cT（A-1）2b≤0，则其零解绝对稳定的充分必要条件是cTb≤0；cTA-1b≥0．2°．假设A＝（aij）3ｘ3，A的特征根均为负实数，cTb＝0，则其零解绝对稳定的充分必要条件为cTA2b≥0；cTA-1b≥0．     

πYpbe直接控制系统绝对稳定的充要条件

<正> 我们考虑Πypbe直接控制系统:X=AX+bf(6)(K)(6=a~TX其中A是n阶方阵,b、a是n维常向量,f(6)∈m={f:f(0)=0;6f(6)>0,当6≠0;f(6)∈(-∞,+∞)}如所周知,我们说系统(K)的平凡解为绝对稳定是指:对于(?)f∈m,(K)的平凡解全局渐近稳定。关于系统(K)的平凡解的绝对稳定性有许多作者进行了很好的研究,得出了不少充分条件;对于充要条件,人们仅在几类特殊的系统中找到了,最近,廖晓昕教授给出了系统的平凡解在一类称之了主要情况下绝对稳定的充要条件[1]。     

Schrdinger方程的一个显格式

本文构造了一个解Schrdinger方程的三层显式差分格式.格式绝对稳定,截断误差为O(τ2+h2).     

Schr(o)dinger方程的一个显格式

本文构造了一个解Schr(o)dinger方程的三层显式差分格式.格式绝对稳定,截断误差为O(τ2+h2).     

具有Ⅳ类功能反应的离散捕食系统周期解的存在性和稳定性

文章讨论了一类具有Ⅳ功能反应的离散捕食系统,获得了该系统的持久性,且当系统为周期系统时得到了其周期解的存在性,并且在适当的条件下该周期解是稳定的。     

Schroedinger方程的一个显格式

本文构造了一个解Schroedinger方程的三层显式差分格式．格式绝对稳定，截断误差为O(τ^2 h^2)．     

存在保护区域的Logistic模型的研究

建立了存在保护区域的时滞Logistic模型,通过分析得到了不存在时滞时模型中存在唯一正平衡解的一个充分奈件和此模型的全局渐近稳定性,而存在时滞时此模型是绝对稳定的．     

Lurie时滞系统绝对稳定的时滞相关条件

讨论了具有控制时滞的Lurie系统在非线性项满足有限扇形区域条件下的绝对稳定性．依据Lyapunov稳定性理论,构造一个适当的Lyapunov泛函,利用线性矩阵不等式的方法,通过一个积分不等式获得了系统绝对稳定的时滞相关条件．并应用schur补引理将以上结果推广到了具有范数有界的不确定Lurie时滞系统,得到了系统鲁棒...     

具有反馈控制的Logistic扩散系统周期解的存在与稳定

利用上下解，Brouwer不动点原理及Lyapunov泛函方法，讨论了一类具有反馈控制的Logistic扩散系统的周期解问题，获得了周期解存在且稳定的判别条件。     

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.     

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.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

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.