定中心

Accompanied with the growth of economics in Taiwan, between Taipei, the political and economical center city, and Kaohsiung, the southern center city, there has been a great amount of increasing traffic volume.

随著台湾的经济成长，政治、经济中心都市的台北，与南部中心都市的高雄，在两地间的交通量激增的背景下，订定了连结这两大都市的高速铁路建设计画。

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。

The Galleria, and other imaginative shopping centers throughout the United States, have led a magazine to title its recent leading article "The Malling of America."

由于盖拉里和美国其他的购物中心，使得一家杂志社在新近的一篇头条报道中把标题定为"购物中心化的美国。"

A new cylinder type forage cutter with high operation was designed and manufactured. Construction design and its performance parameters, helical angle of moving knife, setting height of fixed knife, overload protective device, throwing device and edge shape of fixed knife were analyzed. The results of test were as follows: optimal helical angle of moving knife was 20°, optimal setting height of the center of the cylinder above fixed knife was 20 mm, line speed of blower vane was 13.6m/s ,power consump...

通过对 93ZT - 5 0 0型滚筒式铡草机的设计研究，分析了滑切角、定刀配置高度、定刀刃角对铡草机性能的影响，并对机构设计进行了探讨，试验结果为：动刀的螺旋角为 2 0°；滚筒中心高于定刀 2 0mm ；抛送风机叶片线速度 13.6m/s ；开刃定刀比矩形定刀的功率消耗低 17.5 %；安全防护装置采用牙嵌式安全离合器；研究结果对滚筒式铡草机的设计和应用具有一定的参考价值

Firstly, the article introduces the definition of error of lens center in the old and new national standard, and summarizes three present systems that can confirm the lens center. Then we discuss the theory and formula of self-collimation catoptric method. On the basis of self-collimation theory, some apparatuses were designed (including internal-focusing center scope and center error measure instrument etc).

首先介绍了新旧国家标准关于透镜中心误差的定义，归纳和总结了目前物镜装校定中心的三个体系，讨论了光学系统中心误差自准反射法测量原理、公式和测量方法，以及根据自准反射法测量原理而设计开发的定中心仪器——内调焦定心仪、中心偏测量仪等设备。

The concepts in References 1 and 2 are broadened and the properties of the centrosymmetric and skew centrosymmetric matrices are exploited in detail.

推广了文［1，2］的概念，系统地叙述了中心对称和反中心对称矩阵的性质，导出了一类求解系数矩阵为中心对称和反中心对称线性方程组及超定方程组的缩减算法。

The treatment was performed using 4 to 6 arcs delivering with noncoplanar isocenter beams. 13 patients treated with one target,47 patients treated with multi-targets.60 patients who were treaded with SRT received a mean dose of 54.7±6Gy with a 4～8Gy/f,3f/w,qod regimen,the dose were divided 6～12times.

单靶点X-SRT治疗13例，多靶点X-SRT治疗47例，每次分割剂量4～8Gy，照射6～12次，每周3次，隔日1次，1 中心参考剂量线定在90%，2个中心参考剂量线定在50%～80％，肿瘤剂量42～48Gy。

Steel banding before the foundation set in the center of the cushion, and cross through the center axis for vertical and horizontal, and then through the center ring for radiation tendons and tendon distance and ring the number.

钢筋绑扎前，先在垫层上定出基础中心点，并通过中心点定出纵横十字轴线，再通过中心点定出辐射筋和环筋的距离和环数。

First, the angular velocity function and maneuver load for certain maneuver flight (including hover, dive-hike and these two combined) are set up. The simulation results of the vibration of double-disk rotor system with cantilever supported on rigid bearings show that rotor would be apparently deformed under maneuver load. Second, the performance of oil force of SFD in maneuver flight is analyzed. The results show that in maneuver flight, the SFD with centering spring will become eccentric and its oil force will be time-related and offset-related.

首先，建立了水平盘旋、俯冲拉起及盘旋+俯冲拉起复合机动三种机动飞行条件下的机动角速度函数，并确定了对应机动飞行条件下的机动附加载荷（附加离心力和附加陀螺力矩），分析了带刚支的双盘悬臂转子系统在机动飞行条件下的振动特性，发现发动机转子在机动飞行时会发生明显变形；随后，分析了非定心挤压油膜阻尼器的油膜力特性，机动飞行时，油膜轴颈在机动附加载荷的作用下偏离外环中心，使得带定心弹支的挤压油膜阻尼器也变成了非定心挤压油膜阻尼器，其非定心挤压油膜力是瞬态时变的，并且与SFD油膜轴颈偏移量和进动形态有关；然后，在经典的Jeffcott转子系统中引入带定心弹支的挤压油膜阻尼器，分析了机动飞行时非线性转子系统的振动特性，发现挤压油膜阻尼器油膜力的非协调特性也反映到转子系统的振动响应中；之后，对机动飞行条件下带挤压油膜阻尼器的双盘悬臂转子系统的振动特性进行了分析，并重点分析、总结了俯冲拉起机动飞行时，系统结构参数和工作状态参数（转速比、机动飞行半径、机动角速度等）对该系统振动特性的影响。

First, the angular velocity function and maneuver load for certain maneuver flight (including hover, dive-hike and these two combined) are set up. The simulation results of the vibration of double-disk rotor system with cantilever supported on rigid bearings show that rotor would be apparently deformed under maneuver load. Second, the performance of oil force of SFD in maneuver flight is analyzed. The results show that in maneuver flight, the SFD with centering spring will become eccentric and its oil force will be time-related and offset-related. Then, SFDs are introduced into typical Jeffcott rotor system. The whole system will be statically displaced in maneuver flight and the nonsynchronous components of oil force appear in the response of rotor system.

首先，建立了水平盘旋、俯冲拉起及盘旋+俯冲拉起复合机动三种机动飞行条件下的机动角速度函数，并确定了对应机动飞行条件下的机动附加载荷(附加离心力和附加陀螺力矩)，分析了带刚支的双盘悬臂转子系统在机动飞行条件下的振动特性，发现发动机转子在机动飞行时会发生明显变形；随后，分析了非定心挤压油膜阻尼器的油膜力特性，机动飞行时，油膜轴颈在机动附加载荷的作用下偏离外环中心，使得带定心弹支的挤压油膜阻尼器也变成了非定心挤压油膜阻尼器，其非定心挤压油膜力是瞬态时变的，并且与SFD油膜轴颈偏移量和进动形态有关；然后，在经典的Jeffcott转子系统中引入带定心弹支的挤压油膜阻尼器，分析了机动飞行时非线性转子系统的振动特性，发现挤压油膜阻尼器油膜力的非协调特性也反映到转子系统的振动响应中；之后，对机动飞行条件下带挤压油膜阻尼器的双盘悬臂转子系统的振动特性进行了分析，并重点分析、总结了俯冲拉起机动飞行时，系统结构参数和工作状态参数(转速比、机动飞行半径、机动角速度等)对该系统振动特性的影响。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。