查询词典 frequency analysis

In this paper Ⅰ successfully applied these methods to fault diagnosis, and presenting some new innovative machinery fault diagnosis method; First Ⅰ present a new gear wornout fault diagnosis method, this method use the vibration signal's time-frequency attribute and instantaneous phase undulation to accurately detect gear's fault, and by comparing with the traditional frequency domain analysis method, this method reveals that many nonlinear and nonstationary characteristic exist in gear's vibration, this tell us that if we use frequency domain analysis method without pay attention to the signal's characteristic, we could get wrong diagnostic result; Then Ⅰ present a new bearing fault diagnosis method, this method use ATVFD and Hilbert transform to do envelop demodulation,Ⅰ analyze the envelop with time-frequency method and find out that this method is more accurate then traditional method.Ⅰ also explain that the modulation of the fault to the carrier wave may also be non-stationary and nonlinear; Finally Ⅰ present a cylinder pressure measurement method of diesel engine by means of vibration, cylinder pressure is an important parameter of diesel engine fault diagnosis, the pressure measuring is simplified a lot by this method,Ⅰ also use the ATVFD and time-frequency analysis to realize it.

本文中将上述理论方法成功地应用到故障诊断中去，提出了几点创新性的诊断方法；提出了一种齿轮磨损故障诊断的新方法，该方法利用振动信号能量的时频域分布特征与瞬时相位波动特征可以进行精确的齿轮故障诊断，并通过与传统的频域诊断方法的比较，揭示出齿轮振动中存在的明显的非线性与非平稳特征，说明了不加选择地利用频域分析方法进行齿轮故障诊断很可能会得到错误的诊断结果；提出了一种轴承故障诊断的新方法，该方法利用ATVFD分解与Hilbert变换进行包络解调，并对解调得到的包络信号进行时频域分析，可以实现更加准确轴承故障诊断，说明了故障对载波信号的调制往往也是非平稳与非线性的；提出了一种利用振动信号进行柴油机汽缸内压力检测的新方法，柴油机汽缸压力的变化是柴油机故障诊断的重要参数，利用振动方法可大大简化汽缸压力的检测过程，该方法也是综合利用ATVFD分解与时频域分析方法实现的。

The time-domain response of the induced currents on a scattering object irradiated by a plane wave with a Gaussian pulse in time is expanded as an associate Hermite series in this paper. Using the isomorphism of the associate Hermite function and its Fourier transform, the frequency-domain information can be obtained similarly to the time-domain expansion. According to the corresponding relation between time-domain analysis and frequency-domain analysis, and using the early-time response and the low-frequency information of the induced currents, the non-known coefficients in the expansion series can be decided. The entire responses of the induced currents on the scattering object in both time and frequency domains can be obtained at one time by simultaneous extrapolation computation using both the early-time response and the low-frequency information of the induced currents.

摘要首先根据散射体在高斯脉冲平面波激励下感应电流的能量几乎全部集中在时间轴和频率轴上的有限范围内，该文将时域响应展开为系数待定的连带Hermite级数的叠加，并根据连带Hermite函数的傅里叶变换的自反性，得到与时域响应形式类似的频域响应；然后利用时域方法和频域方法分别计算散射体上感应电流的早时响应和低频信息；最后经过时域和频域联合外推计算，由早时响应和低频信息确定时域和频域响应的待定系数，从而获得了整个时域和频域的完全响应。

Results The tinnitus frequency, severity of subjective tinnitus, audiogram types and some items of function test above hearing threshold were significantly different in the five groups (P.05). Specific features of pure-tone test were found in the five groups: tinnitus frequency was low, whole- frequency hearing threshold high, audiogram even, short increment sensitivity index at 1 kHz high and tone decline at 4 kHz low in the syndrome of invasion of wind-heat; tinnitus frequency was high, high-frequency hearing loss common, audiogram abruptly descending, SISI and TD at 4 kHz high in the syndrome of liver-fire up-stirring; subjective tinnitus was loud, audiogram abruptly descending or gradually descending, SISI and 7W at 4 kHz low in the syndrome of stagnation of phlegm-fire; tinnitus frequency was high, subjective tinnitus low, audiogram markedly descending or hill-like, SISI and TD at 4 kHz high in the syndrome of kidney-essence deficiency; average hearing loss was less, audiogram irregular but abruptly descending or notched in most cases, SISI at 4 kHz low in the syndrome of weakness of spleen-stomach.

结果］耳鸣频率、自觉耳鸣程度、听力图类型及部分阈上功能测试指标在各证型间具有显著性差异(P.05)，这些指标在不同的证型中表现出不同的特点：风热侵袭型的耳鸣频率较低，全频听阈升高，听力图多为平坦型，短增量敏感指数得分在1kHz较高，而4kHz音衰值较低；肝火上扰型的耳鸣频率较高，听力损失以高频为主，听力图多为陡降型，4kHz SISI得分及TD值均较高；痰火郁结型的自觉耳鸣响度较大，听力图以陡降型或缓降型为主，4kHz SISI得分及TD值均较低；肾精亏损型的耳鸣频率较高，而自觉耳鸣响度较低，听力图以显降型或山型为主，4kHz SISI得分及TD值均较高；脾胃虚弱型的平均听力损失较小，听力图无一定规律性，但以陡降型或切迹型为主，4kHz SISI得分较低。

It contains: a continuous guide frequency generating module to generate DPCCH non-guide frequency emission estimation value according to input DPCCH de-spread signal and guide frequency emission signal, and combine the estimation value with the DPCCH guide frequency emission signal to generate continuous guide frequency; an average fading factor generating module to generate average fading factor of each DPCCH code according to the input continuous guide frequency and DPCCH de-spread signal; a demodulation signal generating module to generate DPCCH and DPDCH demodulation signals according to the input average fading factors and DPDCH and DPCCH de-expanding signals at the corresponding time.

这种码分多址通信系统的信号解调装置包含：连续导频产生模块，用于根据输入的DPCCH解扩信号以及导频发射信号，产生DPCCH非导频段发射估计值，并将所述DPCCH非导频段发射估计值与所述DPCCH导频发射信号合并，产生连续导频；平均衰落因子产生模块，用于通过输入的所述连续导频以及DPCCH解扩信号，产生DPCCH各个码元的平均衰落因子；解调信号产生模块，用于通过输入的所述DPCCH各个码元的平均衰落因子，以及对应时刻的DPDCH解扩信号和DPCCH解扩信号，产生DPCCH和DPDCH解调信号。

At first, the last low-frequency image after wavelet decomposition can be an initial approximation of the next low-frequency image. It is tested and verified that the last low-frequency image can diffuse and converge to the next low-frequency image. On the other hand, the next low-frequency image can also diffuse and converge to the last low-frequency image. Above process just presents the gradual variation of wavelet decomposition and reconstruction.

首先，用小波分解后下层的低频图像作为对上层低频图像的一个初始近似，验证了由上层低频图像经方向扩散方程可逐渐扩散收敛到下层的低频图像；反过来，由下层低频图像经方向扩散方程亦可逐渐扩散恢复到上层低频图像，这正体现了小波分解与重构的渐变过程。

No additional data for frequency tracking are need, but higher estimation accuracy and low computational complexity can be obtained. Finally, a kind of optimizing joint algorithm for symbol timing, frequency synchronization and channel estimation is proposed. The false alarm probability and miss detect probability of the symbol timing are derived. We proved that the time－frequency offset domain random sequence sliding in the frequency offset direction is orthogonal with the original random sequence, and proposed a new integer frequency offset estimation algorithm. The coarse estimation methods for fractional frequency offset both in AWGN and multipath channels are proposed too.

最后，提出了一种优化的符号同步、频偏估计和信道估计的联合算法，推导了符号同步方法的虚警概率和漏检概率，给出了随机序列在时间－频率偏移域沿频率偏移方向滑动后与原序列近似正交的证明，提出了一种新的在时间－频率偏移域沿频率偏移方向进行滑动相关估计整数频偏的方法，提出了在AWGN信道和多径信道下进行小数频偏粗估计的方法，给出了小数频偏细估计的ML估计结果和利用频域PN序列取值特性的简洁的信道估计结果。

Zhang Qi pointed out that the RFID application has the different frequency band, low frequency, high frequency and ultra-high frequency, at present will speak the high frequency application was still the market mainstream, in the short-term will not change, in 2008 the high frequency application occupied 70% market share, from now on will keep pace with the times unceasingly carries on the development.

张琪指出，RFID应用有不同频段，低频、高频和超高频，目前来讲高频应用仍是市场主流，短期内不会改变，2008年高频应用占70%的市场份额，今后会不断与时俱进地进行发展。

Similarly, if the strong shear, which could suppress all the scattering in the quiescent two phase region, stopped, the follow-up phase separation also displayed characteristics of anisotropism and relaxation, In this dissertation, the transposed"butterfly'and"streakpattern were observed for the first time within the shear-history-influenced phase separation, which is found closely relevant to the anisotropical relaxation behavior of macromolecules. 5. The phase separation kinetics of PS/PVME under oscillatory shear was further studied on the base of that done under simple shear. It is found that, under specific temperature and strain amplitude, the occurrence of phase separation is strongly contingent on oscillatory frequency and only intermediate frequency could effectively induce phase separation; If all considered oscillatory shear could stimulate phase separation, a fixed frequency can maintain specific most probable phase size and higher frequency yields smaller phase, which makes a higher elasticity but weaker stress relaxation; Furthermore, higher frequency can produces stronger compulsory oscillation on the MPPS but won't change the mean of the MPPS. Under given frequency and strain amplitude, the phase separation kinetics dramatically depends on the phase angle of oscillation and the phase separation corresponding to different phase angle follows different dynamical process.

在简单剪切场下相分离动力学研究的基础上进一步对振动剪切场下PS／PVME的相分离动力力学进行了尝试性的研究，发现：在一定温度和振幅条件下，相分离的发生强烈的依赖于振动频率，只有中等频率的振动剪切才能有效地促进相分离的发生；在都能使相分离发生的前提下，一定频率的剪切能够使体系维持一定的最可几相尺寸，较高频率的剪切导致体系形成的相区尺寸较小，因而体系的弹性效应较强而应力松弛效应较弱；同时，更高频率的剪切对最可几相尺寸的强迫振动效应越强，但不会使最可几相尺寸的平均值发生改变；在一定的振幅和频率条件下，相分离的动力学过程会强烈地依赖于相位角，不同相位角对应的相分离遵循不同的动力学过程但机理一样。

As a differential detection is used between the intercarrier, the proposed algorithm overcome the high sensitivity to timing error of conventional algorithm and is robust to multi-path. The effect of sample frequency offset can't be ignored in a continuous OFDM system of a large number of subcarriers. The estimation precision of the conventional algorithm is low and the realization is complex. A joint estimation of sample frequency offset and fine frequency offset based on difference operation is proposed. As averaging use a large number of samples in a maximum likelihood algorithm, the estimation precision is very high. The use of difference operation cancel the effect of carrier frequency offset, and the proposed sampling frequency estimation algorithm is robust to carrier frequency offset.

最后，本文对连续系统中的采样频率和载波频率精同步技术进行较为深入的研究，由于子载波数目大的连续OFDM传输系统中，采样频率偏差不可忽视，以往的采样频率估计方法精度低、实现复杂，因此本文提出了一种基于差分处理的采样频率偏差和精载波频率偏差联合估计算法，利用了最大似然算法进行采样频率偏差的估计，由于采用了差分处理方法，消除了载波频率偏差对采样频率偏差估计的影响，采用的最大似然算法对大量样点进行平均化处理，所以，相对以往算法，提出的联合算法估计精度高，而且采样频率偏差估计对载波频率偏差具有鲁棒性。

When microgrid is operated in islanded mode, VSGs can be divided into non-frequency regulation units and frequency regulation units, the former can generate power and participates in primary frequency control according to dispatching to mitigate system frequency deviation due to disturbances; the latter can offer referential voltage of microgrid and use secondary frequency regulation to implement no-error frequency control.

微电网孤岛运行时，将虚拟同步发电机分为非调频发电单元和调频发电单元，前者既能按照功率调度指令发电，又能参与一次调频，缓解扰动情况下系统频率的波动，后者提供微电网参考电压，并利用二次调频实现频率的无差控制。

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。