频率

A character-codes model based pattern recognition method by using amplitude data of targets frequency response is proposed after the establishment of high frequency response equation of radar targets. The method uses the same unvariant character-codes to express the same target of different angles and uses sequential separating of regions of target's reference variables to obtain multiple coding vectors of all regions for every target. The category and pose of target can be determined after a two-staged classification processing such as coding processing of target range profile data and errors correcting processing of coded data. The two-stage classification results are used to target identification as posterior hypothesis to be tested by sufficient convincing and necessary convincing. The character-codes model based pattern recognition method is also adaptive to variation of target angles and controllable in error probability. Time-consuming and complicated iterative computation is not necessary in the train process of pattern recognition.

首先建立了雷达目标的高频频率响应方程，这种方程将目标多散射中心理论与目标局部谐振理论有机地结合起来；进而提出了目标多频响应结构成像方法，这种方法将瑞利区频率响应或谐振区频率响应曲线的不同部位用各种不同的近似方法去逼近，通过特征谱估计方法将目标的局部频响特征与宽带距离响应特征结合起来；然后提出了一种基于姿态角变化区域的序贯划分与多模匹配的特征编码识别方法，这种方法具有能适应目标姿态角的变化以及能控制识别的差错概率α等优点，在目标识别时只需要目标在少数有限个频率激励下的幅频响应数据。

In the regular wave tests at the same of slope bottom, the cut off frequency and the frequency of the maximum energy of infra-gravity wave are not changed for different initial wave steepness.

文中以相同相对水深之规则波试验去做比较，在频率方面，波浪尖锐度改变，其截断频率及亚重力波频率无太大的改变，而坡度改变，亚重力波频率会出现移至低频的现象。

Taking the development platform of HVDC power transmission for example, the calculation result of impedance-frequency characteristic of traditional line commutated converter and that of FCC are compared. Simulation results show that the impact of impedance-frequency characteristic of converter on the resonance frequency of AC system is not negligible, and FCC can enhance the strength of AC system in a certain extent, improve system stability and effectively reduce AC equivalent impedance under resonance frequency, thus the harmonic instability of HVDC power transmission system can be avoided.

以直流输电开发平台为例，对传统电网换相换流器(line commutated converter，LCC)与FCC的阻抗频率特性计算结果进行对比，仿真结果表明换流器的阻抗频率特性对交流系统的谐振频率有着不可忽略的作用，FCC在一定程度上提高了交流系统强度，改善了系统稳定性，有效降低了系统谐振频率下的交流等值阻抗，从而更好避免直流输电系统谐波不稳定现象的发生。

Results The amplitude of rabbit stomach in front-back direction rapidly increases after 5 Hz and reaches the peak of 277.5% input at about 8Hz and then deceases gradually. The resonance frequency is 7-9Hz. and the amplitude of vibration is higher than 150% of input amplitude from 6Hz to 10Hz. The resonance frequency reduces and the maximum amplitude increases with the increase of stomach mass and volume.

结果 在2~50Hz频率范围内家兔胃在前后方向的振动在5Hz后振幅迅速增大，在8Hz左右达峰值，达到施加振幅的277.5%，之后又逐渐减小；共振频率为7~9Hz，在6~10Hz频率范围内胃的振幅都超过了施加振幅的150%；随着胃的质量、体积的增大，胃共振频率变低，但最大振幅增大。

Based on the theory of frequency modulation,the principle that frequency jittering spreads the spectrum energy of the voltage and current is analyzed.

针对传统的固定频率PWM控制方式引起的波形频谱能量集中、谐波幅值较大的缺点，文章基于频率调制的理论分析了开关频率抖动技术扩散电压频谱以及电流频谱能量的基本原理，结合传统的PWM控制器，采用三角波作为调制信号实现简单的频率抖动的方法。

According to the method, model dimension is contracted to five by the way of selecting the unit in which amount of I/K is m inimal. Then sensitivity of frequency to stiffness is calculated. After the diff erence between measured frequency and calculated frequency have been got, the ad justed amount of stiffness is calculated by the using of the sensitivity and the frequency difference.

该方法按照I/K最小优先合并原则，将轴系模型自由度数缩聚为5，分析该模型4个刚度对前4阶频率的敏感度，算出实测的前4阶频率和模型计算频率之间的差值，利用敏感度和频率差值计算出刚度的调整量。

RIT control. The receiver incremental Tuning control is used to fine tune to the received singal . This is used in USB and LSB modes to obtain maximum clarity of reception, and in CW mode to control the pitch of the beat note. The RIT Control can tune the receive frequency about 2.3 KHz. This control will not transmit frequency, or the frequency display, but will change the receive frequency.

RIT control ：收信机微调旋钮是用微调调整使你能收到被认为是标准的信号，在USB和LSB模式使用可以获得最清晰的接收，在CW模式可以控制节拍的音调，这个旋钮能在2.3KHz左右调整接收频率，它不影响发射频率和显示频率，但将改变接收频率。

RIT control. The receiver incremental Tuning control is used to fine tune to the received singal .This is used in USB and LSB modes to obtain maximum clarity of reception,and in CW mode to control the pitch of the beat note. The RIT Control can tune the receive frequency about 2.3 KHz. This control will not transmit frequency, or the frequency display, but will change the receive frequency.

RIT control ：收信机微调旋钮是用微调调整使你能收到被认为是标准的信号，在USB和LSB模式使用可以获得最清晰的接收，在CW模式可以控制节拍的音调，这个RIT控制可把接收的频率调整约2.3KHz左右，它不影响发射频率和显示频率，但将改变接收频率。

In tested frequency range, the damping ratio keeps constant under different vibration frequency, which is verified again that the concrete is not the ideal sticky elastic material whose dissipation characteristic is correlative with frequency.

在实验的频率范围内，不同振动频率下的阻尼比近似保持常数，再次证实混凝土并非耗能特性与频率相关的粘弹性材料；砼构件的动刚度随振动频率变化不大，表明其力学参数无明显频变特征。

The proposed algorithm can deal with Carrier Frequency Offset and Sampling Frequency Offset estimation with the presence of frequency dependent In-phase and Quadrature-phased imbalance. Then frequency dependent I/Q imbalance and channel response are jointly estimated.

该联合估计算法能在存在频率相关性I/Q失配的情形下准确获得载波频率偏差和采样频率偏差的估计，并获得频率相关性I/Q失配和信道冲击响应的联合估计信息。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。