电源频率

On the basis of analysis and comparison of conventional and some modern dielectric loss measurement methods in this paper, considering the difficulty consist in the dielectric loss measurement, such as the problem of the locale measurement of dielectric loss the suffering the interference of the electric field in the electrified wire net, the influence of harmonics and the leakiness of frequency spectrum due to the change of the frequency in power supply etc. a new measurement method which the frequency conversion anti-jamming technology combines the fundamental waves phase detachment method is presented.

论文在分析了传统介质损耗测量方法和现代介质损耗测量方法的基础上，针对介质损耗检测中存在的技术问题，如现场测量时工频电网强电场干扰问题、高次谐波影响问题、供电电源频率改变所引起的频谱泄漏和栅栏效应等问题，提出了采用变频抗干扰技术和基波相位分离法相结合的新型测量方法。

An AC powered source usually has a significant level of line frequency common mode voltage.

交流供电的源通常具有很高电平的电源频率共模电压。

What we need is a waveform-less voltage, otherwise we'd hear the twice mains frequency waveform.

但我们需要的是没有波形的电压，否则我们会听到交流电源频率两倍的声波，以及大量失真。

The display operates at mains frequency and the output is approx 120v AC.

显示器工作在电源频率和输出是大约120伏特交流电。

Therefore it can be seen that it will "smooth" the "twice mains frequency DC" into a near constant DC voltage.

因此它可以把"两倍于电源频率的直流电"进行"平滑化处理"，成为一个接近恒定的直流电。

The main content of this dissertation includes: 1. Research on the theory of ultrasonic power supply, introduce its development process. On the basis of these, fix on the scheme of medical ultrasonic low-power supply. 2. According to the principle of modularized design, divide medical ultrasonic low-power supply into four parts. They are power amplify circuit, power control circuit, frequency automatic tracking circuit and matching circuit. Separately research on their theories and design their circuits and necessary programs, especially, effectively resolve the problem tracking the supersonic vibration system with a narrow syntony frequency bandwidth and a high swing. 3. The matching experiments gain good result, and prove that medical ultrasonic low-power supply is entirely up to the mustard on intellectualization, wide band of working frequency, steady output and high efficiency.

本文工作的主要内容包括： 1、研究了超声功率电源的原理，并回顾了它的发展过程，在此基础之上确定本文医用小功率超声电源的设计方案； 2、按照模块化的设计原则，将医用小功率超声电源的设计分解为功率放大电路、功率控制电路、频率自动跟踪电路和匹配电路等四个部分，分别研究了各部分的原理，在此基础之上进行了具体的电路设计和程序设计，尤其是有效地解决了对谐振频率带宽窄振幅高的超声振动系统的频率跟踪问题； 3、通过与超声振动系统的各项配合实验，取得了很好的实验结果，验证了医用小功率超声电源完全满足智能化、工作频带宽、输出功率稳定、输出效率高的设计要求。

An optimization model of electricity and heat efficiency about intermediate frequency coreless induction furnace in the nonmagnetic process is established by using some restriction parameters such as power supply frequency and the diameter of steel stab,and its optimization design is done based on particle swarm optimization algorithms.

以电源频率和坯料直径为约束参数，建立了无芯中频感应电炉无磁性期电热效率优化模型，采用粒子群优化算法对其进行了优化。

Based on these design guides, the analysis and design of a low phase noise and low power dissipation, with 0. 18μm CMOS process, integrated Colpitts crystal oscillator with automatic gain controlled feedback loop as the amplitude-limiting technique, low dropout voltage regulation with band gap reference voltage and frequency tuning monotonicity guaranteed by digitally controlled variable capacitor array is performed to revise influence caused by process, voltage and temperature conditions for. handset. The oscillation with very stable amplitude value and frequency value is achieved.

它利用对工作温度、电源电压和制造工艺不敏感的带隙基准源和在集成电路中元件特性之间匹配好的优点产生了一个不随温度、电源和工艺改变而且可以跟踪工艺变化的参考基准电压，同时通过自动频率控制环路利用数字电路控制可变电容阵列控制瞬态频率稳定度，校正温度、电源和工艺改变对频率的影响，从而可以在很宽的电源电压范围(2.7v—3.7v)和温度范围(-40℃—125℃)以及CMOS工艺参数变化(TT、FF、SS、SF、FS)的条件下提供幅度稳定、频率稳定的振荡输出信号。

However, because of the natural characteristics of the micro and small hole EDM, such as weak discharge energy, high pulse power supply frequency, unstable spark discharge states and small discharge gap, etc., there are still some key technical difficulties in its machining process need to be solved: the difficulties in real-time discharge states detection, in accurate control of machining process, in prediction of discharge states, in improvement of machining system precision and in on-line preparation of micro electrode, etc.

但是由于微细及小孔电火花加工自身具有的放电能量极微、脉冲电源频率高、难以获得稳定的火花放电状态以及放电间隙极小等固有特性，决定了其加工过程仍然存在放电状态实时检测方法单一、加工过程难于准确控制、放电状态难于预测、加工系统精度提高困难和微小电极在线制备困难等关键性技术难点，亟待突破和解决。

A new method used single-chip microcomputer technology which can realize the real-time correcting and automatic tracing with self-exciting frequency of separate-exciting frequency were proposed and with it the safety working situation were assured.

分析了并联型固态感应加热电源它激频率与自激频率不匹配引起停机时电源故障的原因和后果，提出了通过单片机技术实现并联型逆变器它激频率实时修正、自动跟踪自激频率的方法，保证了完成加热后停机过程中逆变器处于安全工作状态，并通过样机试验证实了其正确性和有效性。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。