查询词典 combination frequency

The vibrating wire sensors is excited by single-coil structure and the vibration signal will be feedback through the phototube and MCU.This structure not only simplify the hardware circuit,but also solve the problem of electromagnetic interference which generated by the course of frequency's excitation and pick-up,improve the measurement accuracy and stability of frequency.The application of sweeping frequency makes the vibration wire start-up more stable and reliable.

振弦传感器采用单线圈电磁激振方式，应用光电管结合MCU进行振动信号反馈，不但简化了硬件电路，而且解除了激振和拾振中电磁干扰问题，提高了测量的精度和稳定性；激振中采用的扫频技术也使振弦的起振更加稳定可靠。

In this chapter, three kinds of target recognition methods are performed, which are:①Target recognition method based on the description of polarization parameter plane. The echo polarization states of target are projected onto the polarization state plane described by the ellipticity ε and the tilt angle τ of the polarization ellipse, the change of parameter following ferquency becomes the chart. According to the changing trait of the chart, the multidimensional polarization feature space of target has been contructed. Furthermore, a series of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.②Target recognition method based on the description of Poincare polarization sphere. The echo polarization states of target expressed by Stokes vector are projected onto the Poincare polarization sphere. The conception of polarization ferquency stability, which is used in describing the dynamic distribution characteristics of the target echo polarization states on Poincare polarization sphere, has been defined. A group of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.③Target recognition method based on the description of frequency sensitivity. In accordance with the conception of the polarization state distance defined on Poincare polarization sphere, the frequency sensibility of the physical structure property of target has been investigated, the frequency distribution feature curves in PSD domain are obtained, and targets'features are extracted by means of the curve-fitting method with Least Square Criterion.

这章具体研究了基于三种极化散射特性描述的相应的目标识别方法：①基于极化参数平面描述的目标识别方法，将目标回波极化状态投影到以极化椭圆参数，即椭圆率角ε和倾角τ表征的极化状态平面上，参数随观测频率的变化就形成了图，根据图的变化特点构造了目标的多维极化特征空间，并提取了不敏感目标姿态变化的极化特征参数组来设计目标的识别器结构；②基于Poincare极化球面描述的目标识别方法，采用Stokes矢量表征目标回波的极化状态，并将其投影到描述极化状态的Poincare极化球面上，定义了极化频率稳定度的概念用以刻画目标回波极化状态在Poincare极化球面上的动态分布信息，提取了准方位不变性的目标极化特征，最后设计了目标的识别器结构；③基于频率敏感性描述的目标识别方法，通过在Poincare极化球面上所定义的极化状态距离的概念，研究的是复杂目标物理结构特性对探测信号频率的敏感程度问题，获得了在极化状态距离下的频率分布特性曲线，采用最小二乘估计曲线拟合方法，它既用于极化特征的降维，同时又直接将拟合参数作为目标的分类特征。

The results showed that food ingestion and frequency of the polecat in constant food patches were higher than that in the variable food patches and time of the polecat was the same between two patches during the training period. Only the frequency of the polecat in constant food patches was higher than that in variable food patches when the polecat was starved for 1 day. Its foraging pattern between the two patches was the same as that during the training period when the polecat was starved for 2 days. Meanwhile, the food ingest ion amount in the two patches was not affected by starvation, but the time and frequency of the polecat using the two patches significantly decreased when starvation increased.

研究结果表明，训练期实验中，艾虎对固定食物量斑块中的取食量和利用频次明显高于变化食物量斑块，而对两个斑块的利用时间基本相同；艾虎饥饿一天后对固定食物量斑块中的利用频次明显高于变化食物叠斑块，而对两个斑块的利用时间和取食量基本相同；艾虎饥饿两天后对两个斑块利用程度与训练期的结果相同：同时，艾虎在两个斑块中的取食量均与饥饿程度无关，而对两个斑块的利用时间和利用频次均随饥饿程度明显降低。

This dissertation studies several kinds of instantaneous frequency estimation methods, pay much attention to the performance of instantaneous frequency estimation algorithm based on the peak of time-frequency distribution. It gives the theory and algorithm of polynomial Wigner-Ville distribution, analyzes its performance to the noise of the moving target in the air.

对常用的几种瞬时频率估计算法进行了研究，重点研究了基于时频分布峰值的瞬时频率估计算法的性能，给出了多项式Wigner-Ville分布的原理与算法，分析了在直升机定位这种特定情况下的有效性。

It gives performance comparison of instantaneous frequency estimation algorithms based on the peak of Wigner-Ville distribution and fourth-order polynomial Wiger-Ville distribution, analyzes the influence of window width to the estimation performance of instantaneous frequency estimation algorithms based on time-frequency distribution.

在不同飞行状态下，给出了基于Wigner-Ville分布、四阶多项式Wigner-Ville分布峰值的瞬时频率估计算法的性能对比，并分析了窗长对瞬时频率估计性能的影响。

The change of frequency, draws the conclusion through observing fish's respiratory rate and coughing: Luo is not the respiratory rate of fish and bright cloud porgy, drop with increase of Cu2+ density, cough frequency increases with increase of Cu2+density; Respiratory rate and frequency of coughing of black carp, appear downward trend after rising with Cu2+ increase of density first.

通过观察鱼呼吸频率和咳嗽频率的变化，得出结论：罗非鱼和彩云鲷的呼吸频率，随着Cu2+浓度的增加而下降，咳嗽频率随着Cu2+浓度的增加而增加；鲫鱼的呼吸频率和咳嗽频率，随着Cu2+浓度的增加都呈现先上升后下降的趋势。

The first adjustment was to replace logarithm function by S function for modeling the inner hair cells in cochlea,and the other was distributing frequency bins on frequency axis with the width of frequency bin proportionably increasing.

利用S函数取代对数函数对耳蜗内毛细胞进行模拟，将频率箱按照频率范围等比递增的方式在频率轴上进行分布；同时，利用Gammatone滤波器组进行耳蜗基底膜的建模。

The first adjustment was to replace logarithm function by S function for modeling the inner hair cells in cochlea,and the other was distributing frequency bins on frequency axis with the width of frequency bin proportionably increasing.Furtherm...

利用ZCPA模型对四种转子故障进行了特征提取试验验证，结果表明，该模型只使用少量特征数据(如16个)即可有效表征不同故障，同时，对同一类型故障的特征提取结果具有很好的稳定性和一致性，具有一定的工程应用前景。

The first adjustment was to replace logarithmfunction by S function for modeling the inner hair cells in cochlea,and the other was distributing frequency bins on frequency axis with the width of frequency bin proportionably increasing.Furthermore,the basilar membrane was modeled by Gammatone filterbank.

利用S函数取代对数函数对耳蜗内毛细胞进行模拟，将频率箱按照频率范围等比递增的方式在频率轴上进行分布；同时，利用Gammatone滤波器组进行耳蜗基底膜的建模。

In view of it, the algorithm based on the Fast Fourier Transform techniques with quadratic interpolation in the frequency domain is mainly presented. After that,the simulation is carried on and analyse the simulation curves deeply. It ndicates that this algorithm can not only enhance the frequency resolution, but only estimated frequency has high reliability and excellent stability. And it\'s feasible.

主要介绍一种基于FFT和在频域内二次插值的频偏估计算法，之后进行仿真、深入分析仿真曲线，结果表明该算法不仅可以提高频偏估计的精度，而且频偏估计值具有很高的可靠性和良好的稳定性，该算法是可行的。

So it was last week in Selma , alabama.

上星期在亚拉巴马州塞尔马市发生的事件也是这样一个转折点。

The group also spearheads various social programs in China.

该组织还带头参与中国的各种社会活动。