查询词典 power frequency

In the design of the power supply, the main circuit topology frame uses full-bridge series resonant switching and parallel load connection, in which, four MOSFETs are adopted as the power switches, and by four pulses which UC3879 produces, high frequency operation and fast response are realized. In addition, the MOSFET in the switching power supply has no hard turn-on or turn-off situation in transition, thus the disturbance to the power system is avoided. Especially,by the use of high frequency transformer, PQ50/50, the switching power system can provide the steady discharge current without any amperite.

此开关电源采用全桥软开关技术、串联谐振并联输出，四个MOSFET管为主控制开关元件，通过脉冲产生电路UC3879产生的四路相关脉冲实现了高频交替开关，同时能快速响应输出的各种变化；避免了开关管的硬开关，提高了转换效率，另外通过采用高频变压器PQ50/50隔离了原副边，减小了高次谐波对电网干扰；无需镇流电阻也可实现气体稳定放电。

Simulation results show that, for the fixed sampling frequency, the error rises with the frequency increasing of periodic signal, and decreases with the attenuation time constant increasing of non-periodic signal. The sampling frequency determines the upper limit of appropriate frequency band directly. The research provides the basis for the selection of cutoff frequency in filter design.

仿真结果表明，在采样频率确定时，对于周期信号，计算误差随频率的增加而增大，而对于非周期信号，计算误差随衰减时间常数的增大而减小，采样频率大小决定了插值法用于分布参数模型的适用频带上限，该研究为滤波器设计中截止频率的选择提供了依据。

This experiment is in frequency adjustment X-mitter about that miniwatt frequency adjustment X-mitter operating principle, analyses the debugging making method and their installation, the microphone changes implication into an audible signal, wave an audible signal being modulated as a result of enlarging the day afer tomorrow being in progress to the carrier wave , producing frequency adjustment, by the fact that air wire launching the frequency adjustment electromagnetic wave to the outside , the radio set just can with frequency adjustment meet hear clear implication.

本毕业设计是关于小功率调频发射机工作原理、分析制作方法及其安装调试，在调频发射机中，话筒将话音转化为音频信号，音频信号经放大后对载波进行调制，产生调频波，通过天线向外发射调频电磁波，用调频收音机便可以接听到清楚的话音。

Two common methods of GPS signal coarse acquisition are analyzed and compared in this paper, and an optimized method is adopted. Two common algorithms of calculating fine frequency are analyzed and compared and the conics fitting is designed to calculate the fine frequency. Based on the distributing character of Doppler frequency shift, swing frequency style of Doppler frequency shift search is employed.

对比分析了两种常用的GPS信号粗捕获实现方法，设计了一种优化的实现方法；同时对常用的两种精细载波频率算法进行了比较分析，设计了一种二次曲线拟合的方法计算精细载波频率；基于多普勒频移的分布特点，改变以往顺序搜索的方式，采用跳频搜索的方法。

The traditional analog frequency-sweeping instrument, which mostly uses the LC circuit as the frequency oscillator, is more expensive, too much bigger and heavy to carry. It can only display the curve of amplitude-frequency, but can't used to measure the phase-frequency, and can't used to print the curve of frequency response characteristic either. It brings many discommodity to the user.

传统的模拟式扫频仪大多是用LC电路构成扫频振荡器，它不仅价格昂贵，体积庞大，而且只能显示幅频特性曲线，不能得到相频特性曲线，更不能打印被测网络的频响曲线，给使用者带来诸多不便。

The time-domain response of the induced currents on a scattering object irradiated by a plane wave with a Gaussian pulse in time is expanded as an associate Hermite series in this paper. Using the isomorphism of the associate Hermite function and its Fourier transform, the frequency-domain information can be obtained similarly to the time-domain expansion. According to the corresponding relation between time-domain analysis and frequency-domain analysis, and using the early-time response and the low-frequency information of the induced currents, the non-known coefficients in the expansion series can be decided. The entire responses of the induced currents on the scattering object in both time and frequency domains can be obtained at one time by simultaneous extrapolation computation using both the early-time response and the low-frequency information of the induced currents.

摘要首先根据散射体在高斯脉冲平面波激励下感应电流的能量几乎全部集中在时间轴和频率轴上的有限范围内，该文将时域响应展开为系数待定的连带Hermite级数的叠加，并根据连带Hermite函数的傅里叶变换的自反性，得到与时域响应形式类似的频域响应；然后利用时域方法和频域方法分别计算散射体上感应电流的早时响应和低频信息；最后经过时域和频域联合外推计算，由早时响应和低频信息确定时域和频域响应的待定系数，从而获得了整个时域和频域的完全响应。

A CPU over-frequency method and system is composed of CPU, set module with BIOS ROM and CMOS RAM, control module of peripheral unit, storage module and time clock generation module. CPU over-frquency processing is completed automatically by executing CPU over-frequency program stored in BIOS ROM, meanwhile the highest FSB frequency value of CPU is obtained, and the system and peripheral unit can run at it. A testing for system stability is added to process of CPU over-frequency processing in order to ensure that the FSB frequency is applicable to the operation of CPU and peripheral unit.

一种CPU超频方法以及系统，包括CPU、具BIOS ROM及CMOSRAM的设定模块、外围装置控制模块、存贮器模块以及时钟产生模块组成，经过执行储存于BIOS ROM中的CPU超频程序后，自动完成CPU超频处理，并取得可供系统与外围装置稳定运作的最高的CPU的FSB频率值，于CPU超频处理的过程中，自动加入系统稳定性的测试，确保该FSB频率值适用于CPU与外围装置运作，使系统运作在超频状态下，亦能稳定地工作。

This paper analyzes the principle of chief anti jamming technologies of frequency agile radar FAR frequency diversity radar FDR and self adapt frequency agile radar SAFAR in frequency domain studies the effectiveness measurement methods of these technologies brings forward the self adapt improvement factor which measuring the anti jamming effectiveness of self adapted frequency agile radar .

分析了频率捷变，频率分集，自适应频率捷变等雷达在频域的主要抗干扰技术原理，研究了这些技术的效果度量方法，提出了度量自适应频率捷变雷达抗干扰效果的自适应改善因子。

Result: Contrary to European and American people, I allele frequency of Han nationality is higher than that of D allele (P.05); II genotype frequency and DD genotype frequency are noticeably different from that of European and American people (P.01); No DD genotype appear in the excellent athletes, which is noticeably lower than that of control group and athlete group (P.05) and that of the excellent athletes reported in other countries; the frequency distribution of II genotype in Marathon is noticeably higher than that in 5km distance running(P.10); The changing of I allele Jl genotype IP ID genotype frequency indicates a stronger unary liner relation (r=0.9985) with the running distance lengthening(5ktru lOkrru Marathon).

结果显示：与欧美人群相反，汉族I等位基因频率高于D等位基因（P＜0.05）；汉族II型纯合子频率和DD型纯合子频率非常显著地区别于欧美人群（P＜0.01）；在优秀运动员中，DD型纯合子未出现一例，显著低于对照组和运动员（P＜0.05），也显著低于国外已报道的优秀运动员；马拉松项目II型频率分布显著高于5km（P＜0.10）；I等位基因、II基因型和ID基因型的频率变化伴随专项距离（5km、10km、马拉松）的增加呈现强相关的一元线性关系（r=0.9985）。

The realization monolithic integrated circuit system double audio frequency, this radio has used double audio frequency decoding chip MT8870, demodulates the tonic train signalling from the frequency-modulated signal, and separates the double tonic train signalling from the tonic train signalling to enter the double audio frequency decoding electric circuit implementation letter command to decode, thus carries on the low gear rate using the frequency modulation channel the control command transmission.

为实现单片机控制的双音频解码，本收音机采用了双音频译码芯片MT8870，从调频信号中解调出音频信号，并从音频信号中分离出双音频信号进入双音频解码电路实行信令解码，从而利用调频信道进行低速率的控制指令的传输。

Hanna: That's over now, isn't it?

都结束了，对吗

You must be ill. You look so pale.

你一定是病了，你的脸色苍白。