查询词典 excitation condition

In addition, equivalent series reactance of excitation transformer worsens the condition of the thyristor operation, and it can bring transient over-voltage at the moment of switching thyristor. The transient over-voltage will endanger the field winding.

励磁变压器的串联电抗恶化了晶闸管的换相工作条件，并在晶闸管元件导通与关断瞬间引起危及到转子励磁绕组安全运行的过电压。

The test finished in plan cascade wind tunnel in GTE got the frequency spectra of vortex shedding in all kinds of work condition, and realized unsteady cooperative flow type by method of sound excitation.

在中国燃气涡轮研究院完成了全部叶栅吹风实验，获得了某种扩压叶栅叶片表面旋涡脱落频谱随来流工况变化的规律，并通过声激励的手段在国际上首次捕捉到了新一代"非定常耦合流型"。

Based on the analysis of the excitation spectrum, we obtain the superfluid-Mott-insulator phase transition condition, and superfluid velocity of ultracold dilute gas of bosonic atoms in an optical lattice, and point out that the velocity of superfluid can be experimentally adjusted by controlling the parameters of optical lattice.

在长波极限下，色散关系是线性的，这与无外场时的色散关系相同。从激发谱分析可得到superfluid-Mott绝缘相变条件，给出了光格子中超流速度，并指出在实验上可以通过控制光格子参数来改变超流速度。

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

Key words weak parametric excitation;stability analysis;condition to avoid resonance;methods of multiple scales;excitations of different frequencies

并借助这一正交关系推广文［3］的工作，运用多尺度法分析了一般多自由度单频弱参激振动系统的稳定性。

It was in doubt for long time whether the static-excitation could be used to improve Subsynchronous Resonance condition in a certain power system with serial compensation.

汽轮发电机采用静止励磁方式使轴系缩短并减少了一个质块，是否可以去掉有危害性的扭振频率，而扩大串补系统中次同步谐振安全运行区范围的问题为工程技术人员所关心。

So, the primary condition to improve the self-excitation, can through the dynamic analysis result for complete structural of the machine tools to finish the structure design.

因此改善自激激振的先决条件，可藉由工具机整机结构的动态分析结果，来完成结构设计。

In the study of the stochastic chaos in simple pendulum, the random Melnikov process is derived and the mean-square criterion is used to determine the threshold amplitude of the bounded noise excitation for the onset of the chaos or random chaos in the system. For the coupled simple pendulum and harmonic oscillator, the Melnikov function is used to determine the condition for the onset of chaos in the case of Hamiltonian perturbations. In the case of non-Hamiltonian perturbation, the generalized random Melnikov process and mean-square criterion are used to determine the threshold amplitude of the bounded noise for the onset of random chaos.

在随机混沌研究中，应用随机Melnikov过程的均方准则研究了单摆在有界噪声激励下发生混沌或随机混沌时有界噪声激励的临界幅值；对于耦合的单摆-谐振子系统，先用Melnikov函数研究了在哈密顿扰动下发生混沌的必要条件；然后用推广的随机Melnikov过程方法研究了在非哈密顿扰动下发生随机混沌的必要条件；用最大Lyapunov指数及Poincaré截面方法结果与上述理论结果作了对比。

An idea for analyzing aproblem of piezoelectric dynamics,that treats the excitation of the electricfield in a piezoelectric media as an external exciting action acting on thepiezoelectric media and simultaneously regards the piezoelectric media as anormal elastic media,is given based on the analysis of the electromechanicalcoupling relationships in the piezoelectric media under dynamic condition.

在分析动态情形下压电介质中机电耦合关系的基础上，提出将压电介质中电场的激励作用处理为作用于压电介质的外界激励作用，同时将压电介质视为普通弹性介质的分析压电动力学问题的思路。

The influence of acidity and concentration on fluorescence and absorption spectra were investigated. Using quinine bisulphate as a reference, fluorescence quantum yield of aesculetin in the condition of pH=9.32 was determined to be 0.13 at excitation wavelength 365nm.

考察了酸度与浓度对其荧光性质和吸光性质的影响，以硫酸奎宁为参比，测得秦皮乙素水溶液在pH=9.32，激发波长365nm条件下的荧光量子产率为0.13。

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如果你不幸失恋了，请告诉我，我会帮助你摆脱困境，真的，请联系我啦！

China's plan to cut energy intensity by 20 percent and pollutant discharges by 10 percent between 2006 and 2010 is a case in point.

中国计划在2006年到2010间降低20%的能源强度和减少10%的主要污染物排放，就是一个这样的例子。