频率调制

The modulate methods for convertors equipped with igcts have much more difference from that with igbts.

由于igct器件比较低的开关频率，使得基于它的变流器的调制方法与一般的基于igbt的变流器有很大的不同。

A comprehensive theory is presented for FM spectroscopy of Doppler-broadenedMolecular iodine absorption lines. The relationship betWCen FM spectrOscopy andmodulation frequency and modulation index has been stUdied. The whole circuit forthc frcquency stabilized laser system has been developed.

建立了多普勒加宽碘分子线性吸收FM光谱的一般理论，对FM光谱与调制频率和调制度的关系进行了研究；并研制了532nm Nd：YVO_4/KTP碘吸收稳频激光器的电路系统；提出了虚拟激光稳频技术的概念。

At a low temporal frequency 5Hz,peak responses occured in response to the maximum(in on-center cells or minimum (in off-center cells) luminances of light modulation with an identical delay.

在低的刺激频率(5Hz)下，给光中心和撤光中心细胞的反应峰值延迟时间(相对于光调制信号的最大和最小值)也相同，表明它们具有相同的反应潜伏期。

That microwaves, perhaps modulated with low biological frequencies, are used from a distance to cause performance decrements and disorganization by interfering with neuro-electric function; or by causing central nervous system effects, subjective feelings of ill health, or health syndrome associated with periodic exposures at intensities below 10,000 microwatts/cm^2

微波经过低生物频率的调制后，被用来作为神经电功能的远距离作用武器，以引起行为的衰退和混乱，或者引起神经中枢的各种反应，被动的非健康的感知觉，或者其他的身体的综合病症。

Multiple modulators are provided, a respective one of which corresponds to a respective one of the radio channel frequencies.

提供多个调制器，其相应的一个对应该无线电通道频率相应的一个。

The frequency stability of 9×10-14 at 1 s integration time at three-pass was estimated.

通过吸收程优化过程获得的调制转移光谱信号用于激光频率稳定控制，有望获得更高的稳频精度。

Time (3Xrpm) turning table speed. In addition, while the teeth of the tri-cone bit interact with the formation, the drillstring will generate tiny axial vibration. As the vibration is symphonious to the tri-spine well bottom, the vibration signal exhibits amplitude modulation character. This character had been verified by in-site measurement data and numerical simulation.

另外，三牙轮钻头与地层作用破岩时牙轮牙齿产生啮合振动，由于三脊状井底对啮合振动进行幅度调制形成调幅信号，根据调幅信号的频率特征，振动信号在频域表现为具有一定边带的一束谱线，它是钻头工作正常的&健康信号&。

The experiment shows that:(1) In certain light intensity and electric field ranges (145～305V/cm) the material Si∶ with a resistivity of 1E4Ω·cm exhibits a current oscillation phenomenon at liquid nitrogen temperature;(2) At a certain electric field,the waveform of the current oscillation is stable and does not change with time;(3) The dependence relation between the oscillation frequency and light-intensity can be expressed by f=f0(L/L0)α where L0 is the minimum light-intensity needed to stimulate oscillation,f0 is the frequency under L0,L is the intensity of the light,and α is a coefficient that increase with electric field;(4) The modulating coefficient K K=(Imax-Imin/Imax decreases as the light increases;(5) The maximum value of the oscillation Imax decreases with the increase of the light-intensity while the minimum value of oscillation Imin increases slowly.

结果表明：在一定光照和电场范围内（276～305V/cm ，电阻率为10.4Ω·cm的材料在液氮温度下显示出电流振荡特性；在一定的电场下，电流振荡波形是固定的，不随时间变化；振荡频率随光照强度的增大而线性增大；调制系数随着光强的增强而减弱；振荡的最大值随着光照强度增大而减小，最小值随着光强增大而缓慢增大。

The designed controller can operate at fixed frequency without an internal oscillator,which has better output voltage ripple.

AOT控制保证了转换器在无需内部振荡器的条件下，工作于固定频率脉冲宽度调制模式，并改善了输出电压的纹波特性。

A new type high efficiency synchronous step-up DC/DC converter for hand-held device is designed in this thesis. It works in the PFM mode, and its switching frequency can up to 500 KHz. It offers a built-in synchronous rectifier that reduces size and cost by eliminating the need for an external Schottky diode and improves overall efficiency by minimizing losses.

本文设计了一种用于移动电子设备的高效同步整流的DC/DC升压芯片，该芯片采用PFM调制方式，工作频率最高可达500 KHz，内部集成功率管作为同步整流管，代替传统的肖特基二极管，导通电阻仅有0.4？

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。