加速度

Based on definitions of stress and strain, and the D'Alembert's principle, stress and strain of soils at various depths were derived from the data of acceleration, displacement, as well as excess pore pressure measured in the test. The stress paths and stress-strain relationships of saturated sand during the shaking event, and their connection with development of excess pore pressure were revealed.

根据应力和应变的定义以及达朗贝尔原理，由试验观测的土体加速度、位移和孔隙水压力数据直接推导得到不同深度处砂土的应力和应变，揭示了振动过程中饱和砂土的应力路径和应力-应变关系演化过程，以及与超静孔隙水压力发展的联系。

Toward any tiny object , when we apply d'Alembert theory , we must consider stress , body force and the inertia force of elastic objects caused by acceleration .

对于任取的微元体，运用达朗伯尔原理，除了考虑应力和体力以外，还须考虑弹性体由于具有加速度而产生的惯性力。

It can be concluded that the feature of position curve of water in jig is the same as the curve of typical damped vibration. In the equations the motion parameters of water in jig, such as velocity, acceleration, force etc. are in a direct proportion to the air pressure, and have a definite non-linear relationship with jigging cycle, thickness, and mobility of jig bed.

结果表明，水流运动的位移曲线特性符合阻尼强迫振动规律，水流运动的位移、速度、加速度、受力、动能等运动参数与跳汰机风压有直接的线性关系，与跳汰周期、阻力、床层松散度等跳汰参数有明确的非线性关系。

Characteristics of free vibration and forced vibration of a damped system with dry frictional damping,viscous damping and c x·2 damping are analyzed and calculated,acceleration response of free-vibration of the dry frictional damped system has a sudden change when x· is zero,the change value is constant and depends only on the natural frequency ωn and the displacement xk due to dry friction.

本文对存在干摩擦阻尼、粘性阻尼和c.x2阻尼系统的自由振动及受迫振动特性进行了解析及数值计算，得到干摩擦阻尼系统自由振动的加速度响应在速度零点有一突变，这一变化量为定值，且只与系统固有频率ωn及摩擦当量位移xk有关。

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。

Time history method is universal, it can solve displacement, velocity and acceleration of structure at every time during earthquake, so it can get shearing force, damping force and seismic force at every time.

而时程分析法是一种普遍适应的方法，可以求出地震过程中每一瞬时的位移、速度和加速度反应，从而也就可以得到每一瞬时的构件剪力、阻尼器出力和地震力。

And an integrated navigation algorithm based on the dead reckoning system is put forward in this paper. The algorithm makes use of the output of accelerometers and navigation parameters to update the velocity of SINS.

该算法在传统的航位推算算法的基础上，利用惯组中加速度计组合的输出和航位推算给出的位置与姿态完成了惯导速度更新。

VC-1 acceleration only accelerates deblocking and motion compensation.

VC-1加速度只加速解冻和运动补偿。

Based on the practical process, this paper presented a method to compute the deceleration distance in real time.

基于插补的实际情况，给出一种实时计算减速距离的方法，在此基础上，实现了基于梯形速度曲线的速度平滑处理以及基于S形速度曲线的加速度平滑处理。

This paper measured the constitutive relation of soil in the condition of the low stain-rate by Split Hopkinson Press Bar technology. It offers the reference for study in high stain-rate in the future. And simulated the explosion between soil and concrete by finite element dynamic analysis software LS-DYNA3D. Finished the numerical simulation for power of exploding between soil and concrete in different position of detonator and different scale model. Set out the curves of displacement, velocity, acceleration and pressure of different position. Obtained the destructibility of concrete target in different explosion condition. It offers data reference for theory studying and engineering designing.

本文首先利用分离式Hopkinson压杆实验技术测定了土在低应变率下的本构关系，为以后进行较高应变率下的研究提供了参考；后面着重利用三维显式非线性有限元动力分析软件LS-DYNA3D对土壤混凝土介质中的爆炸进行了数值模拟，采用土壤混凝土分层介质模型，完成了不同装药位置、不同缩比模型的混凝土模型中爆炸威力的数值模拟，测定了不同情况下的压力曲线及典型位置的质点位移、速度、加速度和压力，得出了混凝土靶在各种不同爆炸条件下的破坏情况，为理论研究和工程设计提供了数据参考。

She gently rebuff ed him, but agreed that they could be friends

她婉言拒绝了，但同意作为朋友相处。

If in the penal farm, you were sure to be criticized.

要是在劳改农场，你等着挨绳子吧！