充分条件

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 result shows that: The variation rhythm of the sensitivity index changed unanimously for Jensen,Blank and Stewart water production functions of spring wheat in Liangzhou city,the volume is small in the former stage,then become large at the middle stage,and less at the last stage. Jensen and Stewart water production functions are better of spring wheat in Gulang County in 1987-1989. The Variation rhythm of water deficiency sensitive index is unanimous: the volume are small at first,then large at middle,and diminish at last. The Variation rhythm of water deficiency sensitive index is unanimous in Jensen,Blank and Minhas of flax in Liangzhou county in 1987-1989. The water deficiency sensitive index in Gulang district in 1987-1989 models bad,are too many minus. 3 Establishing the non-linear model to definitive the irrigation quota and dimension of single crop,according the three prototype Precipitation,allocating the limited water optimally according to full water supply,95 percent,75 percent and 50 percent. Economy benefit is the biggest aim function,so getting three groups for irrigation quota,irrigation dimension and benefit,the biggest benefit is the most optimal result.

结果表明：1985-1986 年凉州春小麦Jensen 模型、Bl(来源：10a1ABC论文网www.abclunwen.com)ank 模型和Stewart 模型的敏感指数变化规律接近一致，在前期较小，中期增大，最后再减小。1987-1989 年古浪春小麦水分生产函数以Jensen 模型和Stewart 模型拟合较好，其敏感指数变化规律比较一致，敏感指标值前期较小，中期增大，后期又减小。1983-1985 年凉州亚麻水分生产函数以Jensen 模型、Blank 模型和Minhas 模型敏感指标值变化规律比较一致：先减小，后增大，最后再减小。1987-1989 古浪亚麻敏感指数出现负值较多，模型拟合较差。3 建立单作物种植条件下灌溉定额与灌溉面积的确定的非线性规划模型，将有限的水量按照充分供水，95%、75%和50%供水来分配水资源，以经济效益最大为目标函数，得出三组灌区灌溉面积和效益结果，其中以效益最大为最优解。

Keynesians, monetarists and the rational expectations school all agree that the essence of demand-pull inflation is too much speeding beating against a limited supply of goods producible at full employment.

凯恩斯主义者、货币主义者和理论预期学派都同意，需求拉动通货膨胀的实质在于，过多的货币支出追逐在充分就业条件下可生产出来的有限的物品供给。

The thesis descriptively analyzed the current situation of agricultural product resources in Jiang-han plain, studied the situation of different agricultural product resources in different areas and proposed that full use of different agriculture product resources should be made.

对江汉平原农产品的资源现状进行了描述性分析，研究了适合江汉平原不同县、市农产品资源的生产状况，提出了充分利用各地不同自然条件发展农产品资源的思路。

It is helpful for us to construct difference approximation schemes for HJ equation with aids of schemes for conservation laws.

众所周知，即使在初值条件0是充分光滑的情况下，一般来说，虽可以得到式(1 )的连续解，但其解的导数却是间断的。

When diffuse reflection is used, experiment condition, powder size and sampling should be considered.

采用漫反射方法时，必须充分考虑粉末颗粒度以及装样等实验条件的选择。

The reserves of alluvium and diluvium groundwater has better deposited condition, and the supplement of water resource is abundant; but most of flows-in lake basin area is lacustrine facies sediment, and/or the weather, water resource exist mainly as solid form, and the groundwater resource is indigence.

南部河谷冲洪积层储水条件较为优越、且补给水源充分，其地下水和地表水构成了一个统一的水资源系统和完整的水生态体系；而北部内流湖盆地区多为湖相沉积、且受气象因素制约，水资源多以固体形式存在，因而地下水资源总体贫乏。

If the latter possess native sagacity, and a nameless something more- let us call it intuition; if he show no intrusive egotism, nor disagreeably prominent characteristics of his own; if he have the power, which must be born with him, to bring his mind into such affinity with his patient's, that this last shall unawares have spoken what he imagines himself only to have thought; if such revelations be received without tumult, and acknowledged not so often by an uttered sympathy as by silence, an inarticulate breath, and here and there a word, to indicate that all is understood; if to these qualifications of a confidant be joined the advantages afforded by his recognised character as a physician- then, at some inevitable moment, will the soul of the sufferer be dissolved, and flow forth in a dark, but transparent stream, bringing all its mysteries into the daylight.

假如那医生有天生的洞察力，还有难以名状的某种能力——我们姑且称之为直觉吧，假如他没有流露出颐指气使的唯我独尊，他自己又没有鲜明的难以相处的个性，假如他生来就有一种与病人脉脉相通鲍能力，借此使病人丧失警觉，以致自言自语地说出心中所想的事，假如他平静地听到这些表白，只是偶尔用沉默无声的同情，用自然而然的喘息，以及间或的一两个字眼，表示充分的理解，假如在一个可信赖的人的这些品格上加上他那医生身分所提供的有利条件——那么，在某些难以避免的时刻，患者的灵魂便会融解，在一个黑暗而透明的小溪中涓涓向前，把全部隐私带到光天化日之下。

The introduction of line searches requires the solution of sub-problems must be a dropped direction, that is g T k δ k 0, In this paper, we study the existed methods of solving sub-problems, prove Zhang and Xun 1999's dogleg method and Steihaug 1983's conjugate gradient method to meet the condition of adequate decrease, then the solution can be used in line search.

引入线搜索要求子问题的解必须是下降方向，即g T k δ k 0，本文研究了现存的子问题的求解方法，证明了Zhang和Xun1999折线法、Steihaug1983共轭梯度法满足"充分下降条件"，得到的解可以安全实施线搜索。

It is difficult to research dynamic stability of single-layer reticulated domes under earthquake action by Lyapunov dynamic stability theory.

基于这一理念，本文提出了动力稳定性实用判别方法，并在不同荷载和不同计算条件下进行了充分验证。

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！