不稳定状态

In addition, the absolute/convective instability is studied, and the governing region in the parameter plane is declared. It is shown that the absolute instability may become predominant when the electric field or the surface tension is sufficiently large.

另外，研究了单流体射流的绝对和对流不稳定性，在参数平面上给出了它们的控制区域，发现在电场强度足够大或表面张力足够大时，射流可能由对流不稳定状态进入绝对不稳定状态。

The conditional symmetry instability is the intermediate process between the stable and instable states of the atmosphere. The evolution of the atmosphere from the stable to unstable state or from unstable to stable state comes through two stages. The convective-symmetric instability circulation is related with the state and type of the instability. 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. The release of conditional symmetric instability gives rise to a mesoscale rain belt.

结果表明：条件对称不稳定是大气稳定状态和条件不稳定状态之间的中间纽带，大气由稳定向不稳定或者由不稳定向稳定的演变均通过条件对称不稳定来实现；对流对称不稳定环流的形成与不稳定层的配置有关，当低层为条件不稳定而高层叠加深厚的条件对称不稳定时，对流对称不稳定环流低层出现垂直上升气流，高层出现范围较广的倾斜上升气流，对称不稳定能量释放产生中尺度云带。

In terms of the synoptic environment and precipitation characteristics, there were some common characteristics in these two cases. For instance, warm and moist air with the conditional instability atmosphere in the lower troposphere, it was associated with the highest equivalent potential temperature gradient and strong moisture contrast to below 700 hPa. The lower-level convergence was the major produced mechanism of MCS and the low-level southwesterly flow generated convective instability.

从综观环境条件与降水特徵显示，两个案共通特徵包括（1）低对流层属暖湿条件性不稳定大气，（2）最大相当位温梯度以及水气梯度分布於700 hPa以下，（3）低层辐合均为个案中MCS之重要激发机制，（4）有明显低层西南喷流，大气呈现对流性不稳定状态，（5）中层短波槽线的移入，以及（6）高层辐散分流场的存在，提供MCS发展的有利环境条件。

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。

Squeege business card printing and membership card, produced by atomiccenter around the electron cloud is in a relatively stable state, but even if the business card printing and membership card making is slow, when squeege, the atomiccenter worldaround e will be left in an unstable state, our e-pressurs in squeege, generate electrostatic free, therefore, only when the squeege business card printing and membership card at the same time making the squeege pressure fit in order to avoid the emergence of static electricity.

刮板制卡和会员卡制作的速度降低，原子核周围的电子云处于相对稳定的状态，但是即使制卡和会员卡制作速度变慢，刮板压力过大时，原子核周围的电子也会处于不稳定状态，电子会在刮板压力下游离出来，产生静电，因此，只有当刮板制卡和会员卡制作速度慢，同时刮板压力适合的情况下，才能避免静电的产生。

Enterprise is a non-equilibrium system whose subsistence and development is always placed into a reiterative circulating process: non-stability-stability-non-stability, and the management entropy runs through it from beginning to end.

企业是一个非平衡系统，其生存和发展总是处在一个"不稳定状态——稳定状态——不稳定状态"这样反复循环的过程之中，管理熵始终贯穿企业的生存和发展的全过程。

When the bed morphology is in an unstable statement, the variation of bed resistance makes the flow unstable and forms seiche.

当床面形态处于不稳定状态时，河床阻力的变化使水流处于不稳定状态，形成假潮。

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。

There are four typical states of children's strategy use: not thorough state, unstable state, starched state and backward state.

儿童策略的运用表现出四种典型状态：不彻底状态、不稳定状态、刻板状态和倒退状态。

Based on the study of geological background conditions and the factors inducing the failure of dangerous rocks, this paper explains the distribution and morphological characteristics of dangerous rocks in Fengcheng town, provides the classification of the failure modes of the dangerous rocks in this area, and analyses the stabilities of six representative monomers of dangerous rocks qualitatively by stereographic projection method and quantitatively by limit equilibrium method.

文章在研究凤城危岩所处区域的地质背景条件及危岩失稳的诱发因素基础上，分析了凤城镇危岩体的分布规律及形态特征，根据破坏模式的不同对该区危岩进行了类型划分，采用赤平投影法与极限平衡法对该区6个代表性危岩单体的稳定状况进行定性与定量分析评价，经分析判断其均处于欠稳定或不稳定状态，需进行工程治理。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。