查询词典 power frequency

Each kinds of specification intermediate frequency, high frequency, ultrasonic frequency power source, the many kinds of forms smelting, induction heating complete set of equipment, use in the back, nonferrous metal, alloy material smelting, forging and heat treatment.

产品/Product：各种规格的中频、高频、超音频电源、多种形式的熔炼、感应加热成套，用于黑色，有色金属，合金材料的熔炼、锻造及热处理。

to reduce the impact of carrier frequency offset in ofdm system,this thesis designs a new carrier frequency offset estimation scheme for ofdm system.the carrier frequency offset estimation includes acquisition and tracking.we adopt variable step size adaptive algorithm.the acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth.through this method we can not only avoid the feedback by using forward error correction,but also reduce the times of complex multiplication in order to reduce the power consumption of the system.this algorithm not only has low complexity and fast convergence nut also can improve the demodulation performance of ofdm system.computer simulation illustrates the superior performance of the proposed algorithm with regard to estimation accuracy in both awgn channel and multi—path channel.

摘 要：为了减小正交频分复用系统受频率偏差的影响，在ofdm系统中设计了一种新的载波频偏估计算法。频偏估计包括跟踪和捕获两个阶段，文中采用变步长自适应算法来进行跟踪，这个跟踪算法的捕捉范围是整个信号带宽的一半。通过此方法，不但可以利用前向纠错的方式来避免反馈，而且可以缩减复数乘法的次数以降低计算复杂度和系统功耗。该方法运算复杂度低，并具有较好的收敛性，能改善odfm的解调性能。从计算机的仿真效果可以看出无论是在awgn信道上还是在多径信道上都表现出了卓越的性能。

a scheme of channel estimation using cyclic prefix based on the measurement of the low-voltage power line channel model is presented.after obtaining the frequency response of pilot sub-channel under the state of comb-type pilot,the data sub-channel response is obtained by interpolating the frequency response in frequency direction.in the pilot-free data period,the estimation of the channel is carried out by using cyclic prefix in order to improve the performance of system error rate.

摘 要：通过实际测量给出低压电力线的信道模型，在此基础之上提出了利用循环前缀对信道进行估计的方法，即在梳状导频模式时，使用导频获得导频子信道频率响应后，对其在频域方向进行插值得到数据子信道响应，在其后没有导频的序列的数据周期内，使用循环前缀对信道进行估计，从而起到改善系统误比特性能的目的。

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。

The working load of engin e in plowing can be taken for stable and normal random load whose power spectrum peak value is below 2 Hz. The working load of engine in rototilling contains bo th periodic element whose fundamental frequency is rotating speed of the blade s haft and normal random load of which the parts of energy centers in fundamental frequency and others are distributed over wider frequency band.

证实了犁耕作业发动机的载荷可以认为是平稳的正态分布的随机载荷，其功率谱曲线的谱峰在低于2 Hz处；旋耕作业发动机的载荷是兼有随机成分和周期成分的动态载荷，其中周期谐波的基频为刀轴转速，随机成分一部分能量集中于基频以内，部分分布于较宽频率范围。

After multivariable adjustment, consumption of tuna or other broiled/baked fish was associated with specific HRV components, including indices suggesting greater vagal predominance and moderated baroreceptor responses (eg, higher root mean square successive differences of normal-to-normal intervals [P=0.001]; higher normalized high-frequency power [P=0.008]; and lower low-frequency/high-frequency ratio [P=0.03]) and less erratic sinoatrial node firing (eg, lower Poincaré ratio [P=0.02] and higher short-term fractal scaling exponent [P=0.005]) but not measures of circadian fluctuations (eg, 24-hour standard deviation of normal-to-normal intervals).

经过多因素校正，鲔鱼或其他烤鱼的摄入与HRV某些特异性指标相关，包括了反映更强的迷走神经张力的指数和适当的压力感受器影响如更高的正常-正常均方根连续差[P=0.001；更大的正常化高频功率[P=0.008]；更小的低频/高频功率比［P=0.03］以及更少的窦房结电冲动游走（如，更低的Poincaré比［P=0.02］和更高的短期分形定标指数［P=0.005］），但不测量昼夜波动（如24小时正常-正常间期的标准差）。

Its software uses system self-detecting algorithm to assure measurement channel .It uses softening hardware technique software synchronic data sampling to trace the frequency of exterior signal, in other words , it gives sampling control signals 128 times of power net's frequency .It uses Direct Digital Frequency Synthetics algorithm to transform radical sine waveform parameter table into needed current. It uses FFT algorithm to get radical waveform altitude of current ,voltage and resistor .

整个系统在软件设计上采用系统自检验算法保证测量通道可用，采用硬件软化技术--软件锁相环技术，达到对外部信号频率的跟踪，给出频率为电网工频128倍的采样控制信号：直接数字频率合成技术将基波参数表转换成需要的电流信号，采用FFT变换及基波幅度的计算方法得到被测电流、电压基波幅度和电阻大小。

In this paper,the necessity of frequency tracking in ultrasonic cleaning equipmens is discussed.Based on introduction on the principle of the mian circuit of the ultrasonic power supply for cleaning equipmens and the principle of PLL,the output frequency of 74HC4046 is changed by a single chip measuring the phase difference between volage and current.The software of adaptive tracking technique with varied frequency steps is completed.

讨论了超声波清洗机中自动频率跟踪的必要性，在介绍超声波清洗机的主电路原理、PLL锁相环原理的基础上，利用单片机检测超声电源负载的电流、电压的相位差，从而改变74HC4046 的输出频率，完成了变步长频率跟踪软件设计。

At present, the Company electromagnetic vibration feeder, air hammer, level gauge, solenoid valve and control device, screw feeder, belt conveyor, bucket elevator, dust collector, zero speed switches, proximity switches, high-frequency coil , electromagnetic vibrators, vibration hopper, vibration controllers, marking electromagnet, power conditioners, heating units, heating the first, high-frequency cable, high-frequency transformers, ignition transformers and other products have been sold all over the country, has been unanimously praised users .

目前，本公司电磁振动给料机、气锤、料位计、电磁阀及控制仪、螺旋给料机、皮带输送机、斗式提升机、除尘器、零速开关、接近开关、高频线圈、电磁振动器、振动料斗、振动控制器、打标记电磁铁、电源调节器、加热单元、加热头、高频电缆、高频变压器、点火变压器等产品已销往全国各地，得到了用户一致好评。

The reason why secondary power model damage and high frequency relay disoperation usually has been explained, and the suggestions of protection and research are put forward. Systemic experimental study of waveform shape and frequency spectrum distribution of pulse electric field and pulse magnetic field is conducted with manufactured measuring systems. Waveform shape and frequency spectrum of pulse electric field and pulse magnetic field at different place including different impulse voltage and different gap are studied.

使用研制的测量系统对冲击电压放电产生的脉冲电场和脉冲磁场进行了系统的实验观测，得到了较为全面的不同电压、不同放电间隙和不同观测位置的脉冲电场和脉冲磁场的波形和频谱特征，研究了脉冲电场和脉冲磁场与冲击电压、间隙大小和高度的关系，研究了冲击电压放电产生的脉冲电场、脉冲磁场的分布特点等。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷