查询词典 radio-frequency spectrum

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。

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。

They are advocates of green environmental protection energy-saving power supply, has been formed are: crystal-like medium, high, ultra-high frequency induction heating machine, high frequency quenching machine, high-frequency annealing machine, IF forging furnace, medium frequency melting furnace, high-frequency brazing welding machine, such as a series of high-tech products.

他们正在倡导绿色环保节能电源，目前已形成有：晶体式的中、高、超高频感应加热机，高频淬火机床，高频退火机，中频锻造炉，中频熔炼炉，高频钎焊机等一系列的高新技术产品。

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）。

In this paper Ⅰ successfully applied these methods to fault diagnosis, and presenting some new innovative machinery fault diagnosis method; First Ⅰ present a new gear wornout fault diagnosis method, this method use the vibration signal's time-frequency attribute and instantaneous phase undulation to accurately detect gear's fault, and by comparing with the traditional frequency domain analysis method, this method reveals that many nonlinear and nonstationary characteristic exist in gear's vibration, this tell us that if we use frequency domain analysis method without pay attention to the signal's characteristic, we could get wrong diagnostic result; Then Ⅰ present a new bearing fault diagnosis method, this method use ATVFD and Hilbert transform to do envelop demodulation,Ⅰ analyze the envelop with time-frequency method and find out that this method is more accurate then traditional method.Ⅰ also explain that the modulation of the fault to the carrier wave may also be non-stationary and nonlinear; Finally Ⅰ present a cylinder pressure measurement method of diesel engine by means of vibration, cylinder pressure is an important parameter of diesel engine fault diagnosis, the pressure measuring is simplified a lot by this method,Ⅰ also use the ATVFD and time-frequency analysis to realize it.

本文中将上述理论方法成功地应用到故障诊断中去，提出了几点创新性的诊断方法；提出了一种齿轮磨损故障诊断的新方法，该方法利用振动信号能量的时频域分布特征与瞬时相位波动特征可以进行精确的齿轮故障诊断，并通过与传统的频域诊断方法的比较，揭示出齿轮振动中存在的明显的非线性与非平稳特征，说明了不加选择地利用频域分析方法进行齿轮故障诊断很可能会得到错误的诊断结果；提出了一种轴承故障诊断的新方法，该方法利用ATVFD分解与Hilbert变换进行包络解调，并对解调得到的包络信号进行时频域分析，可以实现更加准确轴承故障诊断，说明了故障对载波信号的调制往往也是非平稳与非线性的；提出了一种利用振动信号进行柴油机汽缸内压力检测的新方法，柴油机汽缸压力的变化是柴油机故障诊断的重要参数，利用振动方法可大大简化汽缸压力的检测过程，该方法也是综合利用ATVFD分解与时频域分析方法实现的。

I produced the various models of machines, including high frequency plastics welding machines, metal heat treatment of high frequency, high frequency of the bubble shell packaging machines, high frequency metal, screws implanted dedicated machines, high frequency welding machine at the same time, the suture heat sealing machine.

我公司生产的各种型号机器，包括高周波塑胶熔接机、高周波金属热处理机、高周波泡壳密著包装机、高周波金属网，螺丝埋植专用机、高周波同时熔接机、热气缝合密封机等。

The use of the web to spread fears that flicking the switch on the LHC could create a Black Hole that could swallow up the Earth particularly concerned him, he said.

他说，使用互联网散布恐慌说启动LHC会生成一个可能吞噬地球的黑洞的做法让他感到忧虑。

Not a single word have I written down.

我一个字也没有写下来。