交流交流是指电流在正负最大值之间以特定的频率变动，通常频率为50或60赫兹。
Ac Alternating current (ac) is electric current that alternates between a positive maximum value and a negative maximum value at a characteristic frequency, usually 50 or 60 cycles per second (Hertz).
近年来GARCH模型被广泛地用于对变动频率很高的金融时间序列建模，它能较好地抓住此类时间序列的动态特征。
At present, GARCH type models have been employed to model these high frequency financial time series due to their ability to capture the dynamic characteristics.
大西洋两岸的价格变动的频率都很大。
On both sides of the Atlantic the frequency of price changes varies enormously.
频率微扰商是表示连续元音发声时声带振动相邻周期间的微细变动量； 发声效率反映平均气流率与声能的有效转换率。
PP indicates the amount of irregular vibration of vocal folds and I/F represents efficient transition from MFR to acoustic energy.
Swetnam博士的工作表明，在气象学家所说的中世纪暖期，即公元900年到1300年，气温的变动和火灾的频率密切相关。
Dr Swetnam's work suggests that variations in temperature were well correlated with the frequency of fire during what climatologists call the medieval warm period, from 900 to 1300.
并对相位突变和频率突变的情况进行了仿真研究，说明在相位和频率发生变动时三相锁相环仍能有效地锁定相位，能够满足系统变频的要求。
The simulation results prove that the three-phase phase-locked loop can work well in disturbance situation and variable frequency system when the frequency of the inputs is variable.
介绍了一种利用检测漩涡频率和横向变动升力的方法测量气体质量流量的漩涡式气体质量流量计。
The paper introduces a new kind of vortex gas mass flowmeter, which can measure gas mass flow by testing the vortex frequency and the horizontal varying lifting force.
简述了低应变动测桩的频率理论，推导出了频率公式，得出了激励材质与频率、所测桩长之间的关系。
The frequency theory of law strain dynamic pipe measurement is sketched. The frequency formula is deduced out. The relationship between exciting material, frequency and length of piles is reached.
文中在衬底介质参数的变动下，对一系列FSS反射系数进行了有效计算，计算结果表明了介质衬底的电磁各向异性特性对FSS频率选择特性的影响。
A series of FSS with different medium parameters are computed efficiently, These results reflect the influence of the electrical and magnetic anisotropy on the electromagnetic characteristics of FSS.
文中在衬底介质参数的变动下，对一系列FSS反射系数进行了有效计算，计算结果表明了介质衬底的电磁各向异性特性对FSS频率选择特性的影响。
A series of FSS with different medium parameters are computed efficiently, These results reflect the influence of the electrical and magnetic anisotropy on the electromagnetic characteristics of FSS.
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