有小环的

By choosing suitable design parameters, all the signals in the resulting closed-loop system are uniformly bounded and the norm of the tracking error vector converges to an arbitrarily small neighborhood around zero by using the presented control approach.

通过选择适当的设计参数，提出的控制方法使得闭环系统的所有信号是一致有界的和跟踪误差向量的范数收敛到小的零邻域内。

A predator model with refuge and toxicity is studied. By constructing a suitable Dulac function, it is shown that there is no limit cycle in the first quadrant, thus the globally stability of the equilibrium is proved. Further more, the paper analyzes the influence of refuge, toxicity and harvesting. It is amazing that ① if the death rate of predator is big or the harvesting effort is big, the existence of the predator is unrelated with refuge; if the death rate of predator and the harvesting effort are small, and the refuge is small enough, the population of both species is increased as the increase of refuge;② if d2=0, the increase of d1 has no influence on the prey population, while the population of predator is decreased.

研究一类有避难所、毒素作用和外界捕获影响的捕食系统，通过构造恰当的Dulac函数，证明系统在第一象限没有极限环，从而证明了平衡点的全局稳定性；分析了避难所、毒素、捕获作用对该系统最终种群数量的影响，发现：①当捕食者的死亡率大或其被捕获得多时，两种群的绝灭与避难所的存在无关；当捕食者的死亡率小、被捕获得多且避难所足够小时，随着食饵避难所的增加，捕食者种群数量也随之增加；②当毒素d2=0时，毒素d1的增加对食饵种群最终数量没有影响，而使捕食者种群数量下降。

The conclusions can be drawn through numerical simulation: The hydrate-forming region becomes small with increasing circulation rate and inhibiter concentration, and it is possible to make the hydrate-forming region away from sea floor by increasing circulation rate and inhibiter concentration, thus preventing blowout preventer lines from hydrate plugging; the decrease in gas volume fraction in the annulus due to hydrate formation reduces pit gain, which can delay the detection of well kick; the possibility of hydrate presence at a relatively low gas production rate is much greater than that at a relatively higher production rate; the bottom hole pressure is affected little by hydrate phase transition, and it is allowable not to consider hydrate phase transition when the bottom hole pressure is calculated; shut-in casing pressure cann't truly reflect gas kick due to hydrate formation and the situation is getting worse with time

模拟计算结果表明：溢流期间，天然气水合物的生成区域会随着循环流量的增大或抑制剂浓度的提高而减小，可通过增大流量和抑制剂浓度使水合物的生成区域脱离海底，减小防喷器管线被堵塞的危险；水合物的生成使环空中气体体积分数降低，泥浆池增量减小，给溢流检测带来延迟；当检测到有气侵发生时，水合物藏分解速率比较小时，井筒中生成水合物的可能性要比分解速率大的情况下更为严重；水合物相变对井底压力的影响较小，在工程中计算井底压力时可以忽略；由于天然气水合物的生成使得关井套压值不能真实反应气侵情况，而且随着时间的增加情况会更加严重。

First,this problem is converted into the problem of H_2 opmization constrainedby H_∞performance and pole location,then an auxiliary perfomance function is introduced,andthe former problem can be converted into the optimal problem of minimization of the auxiliaryperformance function with constraints described by a matrix equation,at Jast this problem issolved by lagrange multipliers,and the static output feedback controllers are designed.

首先将文题转化为一个具有H＿∞性能和系统闭环极点位置约束的系统H＿2性能优化问题。进而通过引入一个辅助性能函数，将其转化成有一个矩阵方程约束的辅助性能函数的最小化优化问题，并给出这个问题静态输出反馈控制器的解。

The results show that the addition of surfactant shortens induction time and improves formation rate and volumetric proportion, and the volumetric proportion of synthetic hydrate samples can amount to 136~150; the existence of porous medium delays hydrate formation exiguously; the influence of memory effect on gas hydrate formation is notable, the induction time could be shortened by 10~20 times for the experimental system containing residual pentahedral ring structure.

结果表明：表面活性剂的加入缩短了水合物生成诱导时间，提高了生成速度和含气率，合成的水合物样品含气率达到136~150；多孔介质的存在对水合物的生成有较小的延缓；记忆效应对瓦斯水合物生成影响显著，在拥有水合物分解残余五面体环等结构的实验体系中，水合物生成诱导时间缩短10~20倍。

It is also proved that the proposed algorithm could guarantee the closed-loop system to be uniformly ultimately bounded and the output converges to a small neighborhood of zero, so that ship linear path-keeping control can be implemented.

该算法保证了闭环系统的信号是一致最终有界的，使得系统输出收敛到零的一个较小邻域，从而能够实现船舶的直线航迹控制；而且，该算法不需要高频增益符号的任何信息，还解决了可能存在的控制器奇异值问题。

This paper presents a nonlinear robust adaptive excitation control design procedure for multi machine power systems using back-stepping method. The control objective is to drive machine power angle and frequency to the steady-state operation point, and guarantee that the close-loop system is adaptive to the uncertainties of generator damping coefficient and d-axis reactance, and robust to model errors or bounded disturbances.

利用反步法设计了多机电力系统中的非线性鲁棒自适应励磁控制方案，控制目标是调节发电机功角和频率至稳态运行点的极小领域，并使闭环系统对发电机阻尼系数和电抗参数的不确定性具有自适应能力，且对模型误差和外部有界干扰具备鲁棒性，同时保证各控制器是分散化和本地化的。

Past winners of the spotty jersey include Fausto Coppi, Federico Bahamontes, Charly Gaul, Eddy Merckx, Lucien Van Impe, Bernard Hinault, Luis Herrera, Claudio Chiappucci, Laurent Jalabert, and Richard Virenque. The latter has claimed the jersey a record seven times, but has now retired and the competition is wide open this year.

今年的圆点衫争夺少了环法7届圆点衫得主法国人Richard Virenque，让本届圆点衫得主预测有了不小的难度，因为往往最好的爬坡手都着眼于黄衫的争夺，真正向Virenque这样以圆点衫为第一目标的爬坡好手并不是太多。

Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring , indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a wide range of terrains ranging from old, heavily cratered surfaces to young, tectonically deformed terrain , with some regions with surface ages as young as 100 million years old.

旅行者1％，发现土卫二在土星的轨道弥漫密集区E环，表明两者之间可能的关联，而旅行者2号透露，尽管该卫星的体积小，它有一个由老，重坑坑洼洼的地形等多种表面，年轻，构造变形地形，与表面老化，部分地区年轻的为100 亿岁。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失