激

The conditions of self - excitation and the influence of automatic voltage regulator on power system self-excitation are analyzed and the system reaponse characteristics of power system under self-excitation are summarized.

分析了电力系统自激的产生条件及励磁调节器对自激的影响，研究了自激发生后系统的动态过程，提出了以发电机机端电压、发电机转子角速度以及励磁电流这3个量的变化规律作为判断复杂电力系统发生自激的依据，并以一个典型的双机系统的仿真结果验证了判据的有效性。

So we designed a adaptive synchronizing controller based on hereinbefore hardware environment: first a small magnitude reference signal r is outputted to system through the signal card (to ensure that the vibrating system works in a linear state), and this signal is sent to the moving coil of vibrator through the power amplifier, so vibration is produced through electromagnetic induction. Secondly the vibration signal can feedback to the data acquiring card in the servo system through the acceleration sensor on the Vibroseis reactor M〓 and the base-plate M〓, then the computer can get the current vibrating state y〓 of the coil of vibrator according to the feedback information from the data acquiring card, and give a real time comparing between the current state y〓 and the reference output y〓 of the set-in reference model with current reference input being r , then regulates the correlative controlling parameters according to the error e〓=y〓-y〓 till y〓→y〓, finally normal signal sweeping begins with a certain phase fixed. Meanwhile a synchronization signal for seismic signal record is sent to seismograph from synchronization signal outputting component in the Vibroseis system to perform the controlling process of synchronization of sweeping phases.

为此，我们基于以上的硬件环境设计了一个自适应同步控制器：首先通过信号发生卡对系统输出小幅度的参考信号r(从而保证振动系统工作处于线性状态)，信号通过前置放大器、功率放大器等送到激震器动圈，并通过电磁感应产生振动，振动信号通过可控震源激震器反应块M〓和基板M〓上的加速度传感器反馈给伺服系统中的数据采集卡，工控计算机根据采集卡的反馈信息，获取当前激震器动圈的振动状态y〓，并实时地将该状态与内置的参考模型在当前参考输入r下的参考输出y〓进行辨识，再将两者输出误差e〓＝y〓-y〓对系统的有关控制参数进行调整，直至y〓→y〓，最后在经过某一固定的相位后，开始信号的正常扫描过程，与此同时，由可控震源系统的同步信号输出部件向地震仪送出一地震信号记录同步信号，进而完成扫描相位同步控制过程。

Three conclusions are then made as follows:(1) The surface current density nearby the subsolar point,which is relatively easier to be observed,may be used to largely describe the behavior of the bow shock instead of the total bow shock current.

由此我们得到如下结论：(1)相对容易观测的日下点附近的舷激波面电流密度，可以替代舷激波总电流大致反映舷激波的电流特性。

It is the gas that drives the exciter and accomplishes sympathetic vibration to make stickup layer break off then achieve the goal of clear for tramcar.

以气体自激振动原理，设计了一种激振器，利用气源驱动激振器使矿车达到共振，从而使附着在矿车底部的黏底层自行脱落，达到清车的目的。

The results showed that hyperhomocysteinemia was induced by restraint stress. The highest CBS enzyme activity was seen in rat livers. A decrease in hepatic activities of CBS was found in restraint stress rats. The 29.4%±2.5% reduction in the activity of CBS was accompanied by a 44.1%± 3.4% decrease in its mRNA level. CBS enzyme activity was slightly elevated in the kidney of stressed rats while it was almost undeterminable in the cardiovascular system.

结果可见，束缚应激可导致大鼠高同型半胱氨酸血症的发生； CBS在肝脏具有最强的代谢活性，肾脏其次，而心脏和血液中活性极低；应激大鼠肝脏CBS活性和mRNA水平均显著降低( P 。05)，应激3周时分别为对照组的70.6%±5.9%和55.9%±4.3%。

The study of fluorescence spectrum proved that the excited phenylenerings of amorphous PES copolymer with high density phenylenerings in its main chain could form an excimer with the surrounding unexcited phenylenerings, and the emission peak intensity of excimer was strengthened with the increase of aging time.

荧光光谱的研究证明，非晶态聚醚砜共聚物由于主链苯环密度较高，苯环受激处于激发态时易与周围激态苯环相互作用形成激基缔合物，缔合物发射峰的强度随老化时间增加而增强。

The study of fluorescence spectrum proved that the excited phenylene-rings of amorphous PES copolymer with high density phenylene-rings in its main chain could form an excimer with the surrounding unexcited phenylene-rings, and the emission peak intensity of excimer was strengthened with the increase of aging time.

荧光光谱的研究证明，非晶态聚醚砜共聚物由于主链苯环密度较高，苯环受激处于激发态时易与周围激态苯环相互作用形成激基缔合物，缔合物发射峰的强度随老化时间增加而增强。

The ground-state binding energy of an exciton confined in quantum wires and quantum wells in the presence of a uniform electric field has been calculated under the effective-mass approximation using variational approach.

本文采用变分法研究了外加电场下无限深方形量子线中重空穴激子的束缚能，我们用平面波展开的方法求解在电场作用下无限深方形量子线中电子和空穴的基态能和基态波函数及低激发态的能量和波函数，并用所得到的波函数进一步计算激子的基态及低激发态的束缚能，最后计算了激子的Stark能移。

Angiotensin-converting enzyme also breaks down BRADYKININ, a powerful vasodilator and component of the KALLIKREIN-KININ SYSTEM.

血管紧张素转换酶也分解缓激肽，一种有力的血管扩张剂和激肽释放酶-激肽系统的成分。

Results14.8% of the students of vestibule school were low stress, 68.8% of the students of vestibule school were in moderate stress, 15.7% of the students of vestibule school were high stress.

结果有14.6%的学生处于低应激水平，有69.7%的学生处于中等应激水平中，有15.6%的学生处于高度应激水平；且三组之间的SCL-90各因子差异有显著性(P.01)。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。