查询词典 axial root

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。

Load spectrum determination of tubing inwall proves the tubing is acted by the axial alternating load in a rod pumped well, and all the fractures are located at the root of the tooth.

油管内壁载荷谱测定进一步明确了油管在工作状态下承受轴向拉-拉交变载荷，其断裂部位全部在应力集中的齿根处。

Axial-system torsional oscillation Hopf ramification Nonlinear dynamic state Characteristic root analysis

轴系扭振； Hopf分歧；非线性动态；特征根分析

The results show that, firstly, Stellera chamaejasme L, which rely on their developed axial root system in the 10～40cm soil layer to occupy the competitive priority of volume, length, surface area and so on, in the case of their adaptive faculty to poor surroundings resulting from fruit picking, trampling and overgrazing as well as with the phenomenon of restrained growth among various plants, gradually become the dominant plant in the herbaceous community; secondly, this kind of degraded grassland has not displayed any general characteristic of degradation such as surface exposure, accumulative quantity of vegetation reduced, water loss, soil erosion and so on, therefor, it should be dealt with distinguishingly; thirdly, if"Stellera chamaejasme L Killer"and"Oxytropis ochrocephala Killer"invented by CAS are taken advantage of respectively in the bloom period of Stellera chamaejasme L and at the beginning of florescence of Oxytropis ochrocephala bunge by ultra-low volume spray of 1. 05L/hm〓 and 1. 35～165L/hm〓 dosage separately, the death rates of poisonous herbs may achieve above 95% and 92% correspondently; fourthly, this technology with the characteristics of high work efficiency, exclusive selectivity and convenient operation, is safe to non-target plants and other animals, and has no toxic or side-effect to environment; furthermore, an execution of"Stellera chamaejasme L Killer"spray and a two-year grazing prohibition can be effectively applied on degraded grasslands of"Weed and Poisonous plants Type".

结果表明：狼毒凭借发达的轴根系在10～40cm土层中形成的体积、长度、表面积等竞争优势，以及对采食、践踏、过度放牧所形成的不良环境的适应能力和异株克生现象的存在，逐步成为草群中的优势植物；毒杂草型退化草地没有表现出地表裸露、植物蓄积量减少、水土流失等一般性退化特征，对该类草地的治理应区别对待；应用中科院研制的'灭狼毒'和'灭棘豆'分别在狼毒盛花期和黄花棘豆初花期，以1.05L/hm〓、1.35～165L/hm〓的施用量超低容量喷雾，毒草的死亡率可达到95％、92％以上；该技术具有工效高、选择性专一、灭效高、操作简便，对非靶标植物和其它动物安全，对环境无毒副作用的特点；采用喷施'灭狼毒'+短期禁牧措施，可以有效治理毒杂草型退化草地。

Methods:Twenty-three tooth of 19 patients were examined by using ProMax lateralal sagittal axial panoramic tomographs before the teeth were extracted or orthodonted to assessment location and shape of dental root.

随着影像学检查技术的发展，全景机的操作性能及程序化控制水平明显提高，可进行多种部位投照[1]。ProMax数字化X光机可以投照颌骨牙列断层片。

At the same time, gene interaction was observed in some of characters, transgressive segregation gene interaction was observed in polygenes controlling length of axial root and thickness of root base （ 1cm）, complementary gene interaction was significantly detected in nodule number of lateral root and dry weight of lateral root and nodule number of lateral root, but not detected or significant in the others.

控制主根长性状的多基因间存在互作，互作方式为重叠作用；控制主根粗（3cm）性状的基因间也存在一定的重叠作用，但是作用不明显；控制其他性状的基因都存在互作，表现为互补作用，但互补作用的强弱有差异。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。