查询词典 radio-frequency spectrum

This frequency stabilization system is a self-adaptive thermal compensated frequency stabilization system, which is based on 80C196 single-chip-processor and uses the beat frequency lock as the criterion.

通过该系统的稳频，激光器的拍频稳定度达到1.05%，由于进一步的测试设备正在采购中，光频的稳定度和复现性尚未测量。

The performance of EFT is investigated, which indicates that time-frequency distributions using single-sided window could not accurately trace the variation of the instantaneous frequency, since their performance depend only on the history of the signal, so they are biased frequency estimator.

提出了基于对称阵元互Wigner分布平均的瞬时频率估计算法，这种方法利用多通道数据对时频分布的瞬时频率估计方法的性能进行了有效的改善，并且能够在低信噪比的条件下获得良好的估计效果， 6。

This article first antenna, microstrip theory, the circular polarization technology, the theoretical discussion, in this based on the microstrip antenna of circular polarization method - corner square microstrip antenna, and has done a design simulation , and then do the design and further research to improve and eventually get a resonant frequency (S11 reflection coefficient corresponding to the minimum frequency) for the 1.5GHz and 1.43GHz, the frequency of circular polarization for the 1.46GHz, S11 is less than -10dB relative bandwidth, the VSWR is less than 2 is about 8.8% relative bandwidth, axial ratio less than 3dB relative bandwidth of about 2.2% of the right circular polarization microstrip antenna design case, which proved very good the circular polarization microstrip antenna theory, also fully confirmed by a square corner design is a practical program, and select the appropriate regulation of sticks is indeed able to improve the performance of the antenna.

本文先对天线、微带理论、圆极化技术等进行了理论论述，在此基础上，提出圆极化微带天线的实现方法——切角方形微带天线，并对此做了设计仿真，后又对这一设计方案做了改进及进一步研究，最终得到一个谐振频率（反射系数S11 的最小值所对应的频率）为1.5GHz和1.43GHz，圆极化频率为1.46GHz，S11 小于-10dB 的相对带宽、驻波比小于2 的相对带宽约为8.8%，轴比小于3dB 的相对带宽约为2.2%的右旋圆极化微带天线的设计案例，从而很好的印证了圆极化微带天线理论，也充分证实了切角方形是一种切实可行的设计方案，而选取合适的调节枝则确能提高天线的性能。

Researched influence of frequency on characteristic of electromagnetic wave transmission in tunnels, and analyzed characteristic of electromagnetic wave transmission in circular, arches and curved tunnels by method of metal wave guide, and gives approximate formulas of attenuation rate. Main conclusions we obtain are as follows: in circular,rches tunnels, if frequency is higher, attenuation rate is smaller, it is beneficial for EM waves to transmit, in curved tunnel, higher frequency, more attenuation rate ...

研究了频率对井下电磁波传输特性的影响，采用金属波导法分析了圆形、拱形及弯曲隧道中电磁波的传输特性并给出衰减率近似公式，得出主要结论：在圆形和拱形隧道中，频率越高，衰减率越小，越有利于电磁波的传播；在弯曲隧道中，频率越高，衰减率越大，不利于电磁波的传播；通过特性曲线与井下实验数据相比较得出在900MHz左右为井下无线通信系统传输信号最佳频段。

Under the control of microprocessor, this product with an oscillating implement embedded in can produce mulriple-scanning pulse electromagnetic wave with variable frequency and mulriple frequency conversion ultrasonic. Electromagnetic wave can get rid of the pests around electrical wire and ultrasonic can dispel the pests in other areas of the room. The product sends out frequency conversion signal of ultrasonic to circumambience. Once touches objects, it reflects and permeates the room. The combining of the two waves has mulriple effects on the central nervous and hearing system of the pests such as rats, cockroachs, spiders and ants. As a result, the pests would be on the rack and agonizing or even have the symptom of swivet and twitch.

它由完全内置的震荡器，在微电脑的控制下可产生多重扫描变频脉冲电磁波和复合变频超声波，电磁波主要解决电源线周围害虫的问题，而超声波是要消除室内其余区域的害虫，它向周围发射的变频超声波信号，当它碰到物体会反射，从而能充满整个房间，这两种波迭加在一起所产生的双重功效，对老鼠、蟑螂、蜘蛛、蚂蚁等害虫的中枢神经及听觉系统进行多重干扰，令其感到极度不适，恐慌不安，甚至表现出狂乱、抽搐等症状，并能使其丧失繁殖能力，迫使其逃离原地，从而达到驱赶害虫的目的。

Based on the high frequency power amplifier,a class E resonant high frequency DC/DC and a phase-shifted control strategy are proposed in this paper,the converter based on the idea can heighten switching frequency,reduce the loss of the system,widen the range of output.

以高频功率放大器为基础，提出了一种超高频E类谐振DC/DC变换器的移相控制策略，基于这种思想的变换器可以提高开关频率，降低系统损耗，拓宽输出范围。

Finally, FastICA in time domain is derived based on instantaneous BSS system, and convolutional mixture BSS algorithm in frequency domain is obtained based on convolutional mixture BSS in time domain. Then we combine the two algorithms together and present the complex-value FastICA algorithm in frequency domain, which is a new BSS technique. We merge preprocessing in time domain and correlation coefficient solution in time domain into this new algorithm and present Time-Frequency domain FastICA BSS System.

最后，本文在瞬时混合盲分离系统基础上推出时域FastICA算法，在时域卷积混合盲分离系统基础上推出频域卷积混合盲分离算法，将这两种算法相结合，提出了频域复值FastICA算法，再将此算法与时域预处理方法以及最后回到时域中的利用相关系数求解分离信号方法相结合，从而建立了基于FastICA的时频域盲分离系统，并将其应用到实际环境中的语音信号盲分离中。

The invention relates to an amplifier circuit containing a high-frequency transistor (1) and having a circuit (2) for adjusting the operating point, which provides a base current for the high-frequency transistor (1) according to the voltage released at a resistor (3) which is connected in the collector ring of the high-frequency transistor (1). The circuit (2) has a differentiating unit (20), fed by the supply voltage, which compares the voltage released at the resistor (3) with a reference voltage.

带有高频晶体管(1)的放大器电路具有一个用于工作点调整的电路(2)，其依赖于在连接在高频晶体管(1)的集电极电路中的电阻(3)上下降的电压为高频晶体管(1)提供基极电流，电路(2)具有一个由供电电压馈电的差分节(20)，其把在电阻(3)上下降的电压与基准电压比较。

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。

0Mg/L 6-benzylaminopurine was the optimal concentration of shoots quantity inducing which frequency of inducing shoots and number of shoots per explant were 100% and 11.1 respectively. 0.5mg/L 6-benzylaminopurine was the optimal concentration of shoots length inducing which average length of shoots was 12.0mm. Explant size had significantly effects on direct shoots quantity and length induction. When complete cotyledon used as explant, frequency of inducing shoots, number of shoots per explant and average length of shoots could approach to 100%, 6.7 and 17.1mm respectively. 2.0mg/L silver nitrate could significantly increase shoot quantity induction, both frequency of inducing shoots and number of shoots per explant could be as high as 97.2% and 4.2 respectively. But silver nitrate also could restrain shoots elongation.

结果表明：不同黄瓜品种直接不定芽数量诱导存在显著差异，但长度诱导无显著差异；6-苄氨基嘌呤对直接不定芽数量和长度的诱导作用显著，其中4.0mg/L为数量诱导适宜浓度，其出芽率和每外植体出芽数达到最高，分别为100.0%和11.1，0.5mg/L为长度诱导适宜浓度，其平均芽长12.0mm；外植体的大小对直接不定芽数量和长度均具显著影响，随着子叶的增大诱导直接不定芽的数量和长度增加，其中单片完整子叶为最适宜大小，其出芽率、每外植体出芽数和平均芽长分别达到100%、6.7和17.1mm；硝酸银也对直接不定芽数量诱导影响显著，其中2.0mg/L为适宜浓度，出芽率和每外植体出芽数分别达到97.2%和4.2，但对芽长有抑制作用。

We got alerted a couple of times while we were down south that HETs were on the way to bring us back up north because things were going to go hot again, but it was just rumors.

南下的途中我们不只一次得到警告说重型装备运输车将拉着我们重新北上，因为局势正在变得重新紧张起来，但这只是谣传。

It's the one where they find the ghost in the salt mine.

这一集是演他们在盐矿找到鬼