查询词典 radio frequency

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。

The dynamic performances of the II type and mainframe tripled frequency converter are researched, on the basis of which the experimental mode test of the II type tripled frequency converter is completed and the shell of the mainframe tripled frequency converter is optimized, which has laid the foundation for the following design and improvement.

本文主要针对Ⅱ型三倍频组件和主机三倍频组件的动态性能进行了研究，并在此基础上完成了Ⅱ型三倍频组件的实验模态测试和主机三倍频组件壳体的结构优化，为后续的设计和改进奠定了基础。

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。

According to the frequency-domain convolution theorem, we can prove the peak frequency and phase are frequency and phase of the harmonic wave signal.

根据频域卷积定理证明最大峰值点的频率和相位就是信号的实际频率和相位，依据由卷积关系得出的关于幅值的方程求出校正幅值。

Then is the property of fourier transform detally,it contains linar, symmetry,uncover,switch,time-move,frequency-move,time-differentialcoefficient,frequency-differential coefficient,time-intergrate, frequency-intergrate,odd even, theorem of Parseval ,and theorem of convolution,and make testify to some property,some have the example.

接着详细概括了傅立叶变换的性质，即线性、对称性、折叠性、尺度变换性、时移性、频移性、时域微分性、频域微分性、时域积分性、频域积分性、帕塞瓦尔定理、奇偶性及卷积定理等，对某些性质相应的做了推导，并附有适当事例。

Polymorphism was detected for exon 3 of BMP4 gene in four sheep breeds. For exon 3, three genotypes were detected in four sheep breeds. In Small Tail Han, Chinese Merino, Corriedale and South African Mutton Merino sheep, frequency of genotype AA was 0.017, 0.216, 0.115, 0.429, frequency of genotype AB was 0.102, 0.317, 0.269, 0.500, frequency of genotype BB was 0.881, 0.467, 0.616, 0.071, respectively. Sequencing revealed one singlenucleotide mutation C→A at 305 bp of exon 3 of BMP4 gene in genotype BB in comparison to genotype AA, and this mutation resulted in an amino acid change of alanine→aspartic acid.

对于外显子3的引物，在4个绵羊品种中都检测到3种基因型；统计结果表明：小尾寒羊、中国美利奴绵羊、考力代绵羊、南非肉用美利奴绵羊AA基因型频率分别为0.017、0.216、0.115、0.429，AB基因型频率分别为0.102、0.317、0.269、0.500，BB基因型频率分别为0.881、0.467、0.616、0.071；测序结果表明：BB型和AA型相比在BMP4基因外显子3第305位碱基处发生C→A的突变，该突变导致氨基酸由丙氨酸改变为天冬氨酸；BB型小尾寒羊平均产羔数分别比AB型和AA型多0.61只（P.05）和1.01只（P.05）。

Listen,point and check your answers.

听，指出并且检查你的答案。

Warming needle is one of effective treatment methods for knee arthralgia aggravated by cold,and it is simple,safety,so it should be developed in clinical acupuncture and moxibustion extensively.

但以本院科针灸门诊在2005年1月—2006年6月期间共收治膝痛患者100余例，经过临床的诊断后，其中施以温针治疗的48例，疗效显著，报道如下。1临床资料本组病例48