查询词典 frequencies

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

An equal cross-section blade was investigated and a finite element model was built parametrically. Geometrical parameters (such as length, width and thickness), material parameters (such as young's modulus and density) and speed of blade were considered as input random variables while the static frequencies and dynamic frequencies were output random variables. Combining the finite element method, response surface method and Monte Carlo method, the statistical properties and cumulative distribution functions of static frequencies and dynamic frequencies were obtained. Probability sensitivities analysis, which combined the slope of the gradient and the width of the scatter range of the random input variables, was applied to quantitatively evaluate the sensitivities of static frequencies and dynamic frequencies with respect to the random variables. The Scatter plots of structural responses with respect to the random input variables were illustrated how to adjust the values of the static frequencies and dynamic frequencies by changing input random variables.

文中以某试验台用汽轮机等直叶片为研究对象，考虑几何参数、材料参数和转速的随机性，通过有限元参数化建模，将确定性有限元方法、响应面方法和Monte-Carlo模拟法相结合，从而获得了叶片静频、动频的统计特性和累积分布函数；同时考虑随机变量的梯度和离散范围对静、动频的影响，通过概率敏感性分析，定量地判断出叶片静、动频对随机输入变量的敏感性；通过绘制叶片静、动频与输入变量的散点图，定量地分析了如何改变随机变量以调整静、动频率的方法。

One of the most common ways to describe a wood's tonal properties is in terms of its frequency range,which is often broken down into low-end frequencies,mid-range and high-end frequencies.picture it as a visual spectrum,as we've done in the chart to the right,with the lower frequencies on the left and the higher frequen-cies on the right.the graph line for each wood visually depicts its general tonal range.rosewood and ovang kol,for example,tend to resonate with more low-end frequencies,whereas koa,cocobolo and maple tend to sound brighter from having more top-end frequencies.note also rosewood's"scooped"midrange and ovang-kol's fuller midrange.the doted lines for walnut and koa denote the expansion of low-end frequency range as the guitar opens up after a period of playing it.

最常见的方式描述了木材的声音特性是在其频率范围内，这往往是细分为低端频率，中端和高端frequencies.picture它作为一个视觉频谱，因为我们'维生素E这样做的图表，以权，以较低的频率在左边和更高的频率，种上right.the图线的每一个木材视觉描绘的一般音调range.rosewood和ovang科尔举例来说，往往会产生共鸣更多的低端频率，而兴亚， cocobolo和枫树往往从健全光明有更多的高端frequencies.note也花梨木的"收购"的中端和ovang -科尔的充分midrange.the doted线的核桃和兴亚指扩大低端频率范围内的吉他开辟了一段时间后，打它。

One of the most common ways to describe a wood's tonal properties is in terms of its frequency range,which is often broken down into low-end frequencies,mid-range and high-end frequencies.picture it as a visual spectrum,as we've done in the chart to the right,with the lower frequencies on the left and the higher frequen-cies on the right.the graph line for each wood visually depicts its general tonal range.rosewood and ovang kol,for example,tend to resonate with more low-end frequencies,whereas koa,cocobolo and maple tend to sound brighter from having more top-end frequencies.note also rosewood's"scooped"midrange and ovang-kol's fuller midrange.the doted lines for walnut and koa denote the expansion of low-end frequency range as the guitar opens up after a period of playing it.

最常见的方式描述了木材的声音特性是在其频率范围内，这往往是细分为低端频率，中端和高端frequencies.picture它作为一个视觉频谱，因为我们'维生素E这样做的图表，以权，以较低的频率在左边和更高的频率，种上right.the图线的每一个木材视觉描绘的一般音调range.rosewood和ovang科尔举例来说，往往会产生共鸣更多的低端频率，而兴亚， cocobolo和枫树往往从健全光明有更多的高端frequencies.note也花梨木的&收购&的中端和ovang -科尔的充分midrange.the doted线的核桃和兴亚指扩大低端频率范围内的吉他开辟了一段时间后，打它。

In this study,two SNPs of chicken FASN gene were chosen to analyze genetic diversity and their associations with chicken growth and carcass traits by using a F_2 designed resource population.Results showed that:(1) In the PCR-RFLP site of HaeⅢ,allelic frequencies differed much among different chicken breeds,as B frequencies are the highest in Red Jungle Fowl(0.85),and the lowest in Taihe and Yugan Black(both 0.21).In the PCR-RFLP site of PstⅠ,A frequencies are the highest in Chongren Partridge(0.5),and the lowest in Naked Neck chicken(0.19),and the difference of gene frequencies was small among chicken breeds.

研究了脂肪酸合成酶(Fatty acid synthase， FASN )基因最后1个内含子2个突变的多样性，并运用资源参考家系研究了这2个突变对鸡体重、脂肪沉积性状的影响，结果表明：(1)红色原鸡Hae Ⅲ-PCR-RFLP位点B基因频率为最高(0.85)，泰和鸡及余干乌黑鸡为最低(0.21)，品种间差异较大，但未发现肉用与蛋用鸡种间的差异；在Pst I-PCR-RFLP位点上， A基因频率在崇仁麻鸡中表现为最高(0.5)，在裸颈鸡为最低(0.19)，品种间差异较小。

The static natural frequencies and dynamic frequencies (under 3000rpm) are calculated by the finite element method and cyclic symmetry technique. The rotating vibration behaviors of the two models are compared. Different vibration characteristics between the two models are discussed. Geometry mismatch in a turbine blade root, which arose in manufacturing process or caused by wearing out during service, leads to contact conditions changed in fir-tree attachments. As a result, shifting of the fundamental frequencies and redistribution of stress in the blade base possibly cause failure of the blade.

在叶片—轮盘耦合系统振动研究方面，建立了带围带的叶片振动计算模型和带围带的叶片—轮盘耦合系统振动计算模型，考虑旋转离心力作用，采用波传播技术，对两种模型分别进行了整圈模态分析，得到了某汽轮机叶片模型和叶片—轮盘耦合模型在0转速和工作转速(3000rpm)下的振动模态，并对所得结果进行分析比较，讨论了整圈叶片振动模态与叶片—轮盘耦合振动模态的区别。

Vibration Hull 船体振动 The Builder to determine natural frequencies of vertical and horizontal vibrations for hull girder and deckhouse to ensure that excitation frequencies of main engine and excitation frequencies of propeller are not similar.

建造方应确定船体纵珩和甲板室的垂直和水平方向振动的自然频率，从而使主机的激励频率与螺旋桨的激励频率不同，对船尾潜在的板振动应加以分析并通过相应的设计加以消除。

In study of the truss structural dynamic characteristics analysis, randomness of the structural physical parameters and geomtric ones are all considered. The finite element model of the stochastic truss is built and the random functions of its natural frequencies are obtained by use of the Rayleigh quotient. Employing probabilistic distribution function expression for the random functions, through a series of mathematical processing including determination of limits of integrals, variable substitution etc., the probaabilistic density function for the truss natural frequencies are gained to realige accurate calculation for the reliability of the truss natural frequencies.

考虑结构物理参数和几何参数的随机性，通过构建随机参数桁架结构的有限元模型，利用瑞利商公式获得了结构固有频率随机函数的计算表达式，应用随机函数的概率分布函数表达式，通过确定积分区间、变量替换、积分顺序变换等一系列数学上的处理，获得结构固有频率的概率密度函数，进而实现对结构固有频率可靠度的精确计算。

The frames with low and slowly changing average instantaneous frequencies were identified to be the periodic sonant segments and the frames with high average instantaneous frequencies were identified to be the surd segments based on the characteristics of the average instantaneous frequencies of IMFs derived from speech signals.

根据语言信号特定阶IMF平均瞬时频率的特征，将平均瞬时频率低且变化缓慢的语言帧作为周期性强的浊音段，而平均瞬时频率高的语言帧判别为清音段，组合处理后的结果最终得到语音段数据。

In contrast to revolving speeding of the turbo-charger and the passing frequencies of the blades, the blades syntonic frequencies are obtained. While,I bring forward methods of adjusting frequencies of blades to avoid their resonace.

对比增压器的工作转速和叶轮与涡轮叶片旋转通过频率，找出了叶片共振的频率，并提出了相应的调频措施，从而为控制增压器叶片的振动提供了理论依据。

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。