查询词典 frequency analysis

The every frame image was transformed by dyadic discrete wavelet and the characteristic of wavelet transform coefficient was analyzed. Low frequency coefficients were analyzed by fast principal component method which quoted Gram-Schmidt orthonormalization procedure in fixed-point algorithm then distilled principal component and reconstructed the low frequency coefficients. To suppress image noise, the high frequency coefficients were equated to zero.

该算法对热图像序列中的每帧图像进行二进制离散小波变换，提取出低频部分的系数；对低频系数进行改进PCA分析，通过固定点算法并引入Gram-Schmidt正交化过程求解特征向量；令高频系数为零，抑制图像的噪声。

When population are in noneequilibrium, if we know the genotype frequency of one generation of common population, the genotype frequency of the next or any generation can be calculated on the basis of the panmixia ratio and gene frequency directly.

群体在非平衡条件下，如果已知普通群体某一世代的基因型频率，根据随机交配率、基因频率可直接推算下一代或任一世代的基因型频率。

Broadcast can completely be reborn in narrow broadcast. The strategy of the narrow broadcast is how to realize the specialization of frequency. The specialization of frequency in our country has not been well developed. The specialization of frequency, in the term of audience, is the particularization of audience.

广播的"窄播"策略，实质上就是一个如何实现频率专业化的问题；我国广播的频率专业化还很不充分，频率专业化，从受众的角度来讲，就是受众细分化；广播可以从受众群体、受众需求、接受时间等维度来细分受众，在专业频率中凸现贴近性、服务性和参与性。

The working load of engin e in plowing can be taken for stable and normal random load whose power spectrum peak value is below 2 Hz. The working load of engine in rototilling contains bo th periodic element whose fundamental frequency is rotating speed of the blade s haft and normal random load of which the parts of energy centers in fundamental frequency and others are distributed over wider frequency band.

证实了犁耕作业发动机的载荷可以认为是平稳的正态分布的随机载荷，其功率谱曲线的谱峰在低于2 Hz处；旋耕作业发动机的载荷是兼有随机成分和周期成分的动态载荷，其中周期谐波的基频为刀轴转速，随机成分一部分能量集中于基频以内，部分分布于较宽频率范围。

The correlation detection using the periodicity of the direct sequence autocorrelation function can estimate the symbol period at intermediate frequency or at baseband. Simulation results indicate that the former is superior to the latter when the demodulated frequency is unequal to the carrier frequency.

时域相关检测方法利用扩频信号的周期自相关特性，能在中频和基带对扩频码周期进行估计，仿真结果表明中频检测时性能较好。

Takes several energy saving measures for air conditioning system, such as large capacity centrifugal chillers working with variable frequency small capacity chillers, variable frequency and variable flow control on secondary pump water systems, cooling tower for four-pipe water system in winter, fan-coil unit for commercial peripheral zones and all-air systems for interior zones, variable frequency control on supply and exhaust air fans,...

采用了多项空调节能措施：大冷量离心冷水机组搭配变频小冷量机组，二次泵变频变流量空调水系统，四管制风机盘管冬季用冷却塔换冷供冷设计，商业外区风机盘管、内区全空气空调系统，送风机、排风机变频控制，过渡季、冬季利用室外新风通风降温的焓值控制设计。

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。

Bob Eckert has been chairman and chief executive of Mattel for eight years.

美泰董事长兼首席执行官鲍勃·埃克尔特在任已8年。

The outlook for honors and disgraces carries on and surpasses the traditional outlook for honors and disgraces theoretically, and carries on and develops the theory of construction of socialist mora...

社会主义荣辱观的提出在理论上是对传统荣辱观的一次继承和超越，是对社会主义道德建设理论的继承和发展，在实践上有利于形成良好的社会风尚。