不稳定

When the conditional instability lies in the lower level and conditional symmetric instability in the upper level , the circulation will have vertical updrafts in the lower level and slantwise updrafts in the upper level .

当低层和高层出现条件不稳定，中间呈条件对称不稳定或弱稳定度层结时，从低层到高层出现较深厚的垂直上升气流，湿重力不稳定能量的释放导致了云带的形成。

When the conditional symmetric instability lies in the middle level and conditional instability in the lower and upper levels, the circulation will have updrafts through the total column of the atmosphere. The release of conditional instability gives rise to a mesoscale rain belt.

当低层和高层出现条件不稳定，中间呈条件对称不稳定或弱稳定度层结时，从低层到高层出现较深厚的垂直上升气流，湿重力不稳定能量的释放导致了云带的形成。

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 results show that the decalescence of catalyst bed affects the process of hydrogen peroxide catalytic decomposition greatly. If the catalyst bed is preheated or made up of materials with low thermal conductivity, that influence can be depressed. At the same time, the response characteristic of catalyst bed and the efficiency of catalytic decomposition can be improved. The low frequency pressure instability of catalyst bed occurs because of the coupling of catalytic decomposition and supplying. The decomposition plane pushes all the way through the catalyst bed during pressure oscillations, causing unreacted liquid hydrogen peroxide to be exhausted from the bed and leading to the appearance of liquid hydrogen peroxide channeling. Consequently, how to prevent or at least limit this channeling is the key to eliminate the pressure instability of catalyst bed. It was found that adding clapboard to the catalyst bed can depress the pressure instability efficiently.

结果表明催化剂床及催化剂的吸热对过氧化氢分解过程影响很大，对催化剂床进行预热或采用热导率低的材料制造催化剂床等措施，可以降低催化剂床壁面吸热对催化分解过程的影响，提高催化剂床的响应特性和催化分解效率；催化剂床的低频不稳定是催化分解过程与供应系统耦合产生的，催化剂床气体界面的波动过程中，液体过氧化氢穿透催化剂床形成过氧化氢液体通道，过氧化氢液体通道的产生和扩大是催化剂床不稳定的主要原因，也是消除催化剂床不稳定的关键，试验中在催化剂床内加入分流板成功地抑制了催化剂床的低频不稳定。

Only if these instable elements arrive at some level, the political instability will be changed into reality.

当然，生成和存在不稳定因素只是表明这里存在不稳定的可能性，只有当这些不稳定的因素达到一定的度，才会酿成现实的政治不稳定。

BPH is a common disease in old people, it often causes bladder outlet obstruction and destrusor instability. It is reported that the morbidity, rate of detrusor instability secondary to BPH is from 52% to 80%. There are many hypotheses concerning detrusor instability, The study of detrusor denervational hypersensitivity and changes of detrusor ultra-structure are intensively popular at present. But most of the research work were only limited in animals. In order to gain the insight into its mechanism, we Carried out a series of studies on detrusor instability secondary to BPH obstruction in men.

BPH是老年人常见疾病，常导致膀胱出口梗阻和逼尿肌不稳定，有报道BPH梗阻性逼尿肌不稳定的发生率为52-80％，引起逼尿肌不稳定原因很多，其中逼尿肌去神经超敏和超微结构的变化是目前研究的热点，但大多限于动物实验，鉴于此，我们对BPH梗阻性逼尿肌不稳定进行了初步的研究，拟探讨其发生机制。

In the region upstream of vortex breakdown, the sectional streamlines emanating from the leading edge spiral inward to primary vortex and in the region downstream of the breakdown, on the other hand, the streamlines separating from the leading edge are not entrained into the vortex core in the instantaneous sense. Along the axis, the topology of the primary vortex alters several times starting from stable focus near the apex to unstable focus, and lasts back to stable focus near wake edge, the stable hmit cycle and unstable limit cycle are shown in this evolution.

发现在截面流线谱中，即使奇点的类型、数目及位置相同，奇点的连接方式也有可能不同；旋涡破裂点前，主涡由来自前缘的力线卷绕而成，主涡焦点与前缘半鞍点相连，旋涡破裂后，来自前缘的力线不再卷入主涡，主涡焦点与对称面上的鞍点相连：在流体由翼尖流向后缘的过程中，截面流线谱的拓扑结构发生了多次变化，主涡焦点相继由稳定状态转变为不稳定状态，最后又转化为稳定状态，并先后出现了稳定的极限环及不稳定极限环。

Higter Piso than those with stable bladders, but the bladder capacity and the volume while feeling the first desire to void were decreased significantly in patients with detrusor instability than those with stable bladder.

再根据是否出现DI，把59例BPH病人分为不稳定膀胱组和稳定膀胱组，不稳定膀胱组的I-PSS、尿流加速度和Piso显著高于稳定膀胱组，初次尿液和膀胱最大容量显著低于稳定膀胱组。

The results show that for a supersonic shear layer without reaction, a disturbance can make the shear layer become unstable, this results in one vortex or more than one vortex. The combination and seperation of vortex can intensify the mixing. But it is not easy for supersonic reacting shear layer with exotherm to become unstable with disturbance, and the effect duration is very long.

结果表明，对完全气体的超声速剪切层流动，一定的激励方式能使原先较为稳定的剪切层流动变得不稳定，产生单涡或多涡结构，发生多涡间的合并，使混合加剧；但对于存在放热现象的反应超声速剪切层流动，外加激励方式不易使流动从稳定变为不稳定，而且外加扰动的作用特征时间也较长，实际应用前景不乐观。

The results show that stable organic sulfur is the main s9lfur form in ZY coal. Pyrite can be removed under all the atmospheres in the tests, except for nitrogen at 500℃ 1% O2-N2 atmosphere has strong reactivity to remove the stable organic sulfur in ZY coal, especially at 700℃. Under 1% O2-N2 atmosphere, not only a part of stable organic sulfurs can be decomposed, but also more stable organic sulfur-containing structure can be broken down into less stable one.

结果表明，对于ZY煤而言，黄铁矿和不稳定有机硫除在氮气气氛下500℃时热解不能全部分解外，在其他条件下热解时都可以分解。1%氧气对ZY煤中稳定的有机硫的分解有很强的促进作用，不仅可以脱除稳定的有机硫，还可以使更稳定的有机硫断裂生成次稳定的有机硫，在随后的AP-TPR-MS实验过程中，这部分硫在较低的温度下逸出。

The reasons of iron ions content overproof in grade Ⅱ desalting water system,such as variation water quality,contamination of regenerant , operation adjustment of pretreatment system and switching operation of bed were discussed.

对二级脱盐水系统中铁离子含量超标的原因，如来水水质发生波动、再生剂受到污染、预处理系统操作调整、床体运行切换等进行了论述。

You were hired to drum up new business, so go and do it.

公司雇你招徕新业务，你就做你的事好了。