查询词典 up to the present

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。

Most of these managers have no need to work for a living; they show up at the ballpark because they like to hit home runs. And that's exactly what they do. Their combined financial statements (including those of some smaller operations), shown on page 49, illustrate just how outstanding their performance is. On an historical accounting basis, after-tax earnings of these operations were 57% on average equity capital. Moreover, this return was achieved with no net leverage: Cash equivalents have matched funded debt. When I call off the names of our managers - the Blumkin, Friedman and Heldman families, Chuck Huggins, Stan Lipsey, and Ralph Schey - I feel the same glow that Miller Huggins must have experienced when he announced the lineup of his 1927 New York Yankees. Let's take a look, business by business: o In its first year with Berkshire, Borsheim's met all expectations. Sales rose significantly and are now considerably better than twice what they were four years ago when the company moved to its present location.

大部分的管理人根本就不需要为了讨生活而工作，他们参加球队的原因只是为了要击出全垒打，事实上这正是他们常常有的表现，他们合并的财务报表，显示他们的表现是如此的优异，以历史投资成本做基准，他们现在每年的税后盈余高达平均股东权益的 57%，更甚者，他们并不靠举债，帐上所拥有的现金就足以清偿所有的借款，当我念到这些管理人的名字- the Blumkin， Friedman， Heldman families， Chuck Huggins， Stan Lipsey 与 Ralph Schey ，这感觉就好象是名教练 Miller Huggins 在宣布 1927 纽约洋基队的先发阵容一样。

The study result indicates: the heat flow evolution curve show a general tendency of decreasing slowly interrupted by two picking up periods that shapes' a saddle' from the Paleocene to the Present.

结果表明：（1）该区自古新世以来，热流的演化形态近似于"马鞍型"，中间有二次回升，但回升的幅度逐渐变小；古新世早期的大地热流值为83。

It may be difficult to face up to the grim realities outside the Matrix, but the movie does present this as a choice worth making.

也许确实很难面对Matrix外的严酷现实，但是电影确实告诉我们这是一个值得的选择。

At present, the package, test, design and manufacture technology of the semiconductor integrate circuit make up to the three stanchion of semiconductor industry.

目前，半导体集成电路的封装、测试与设计以及制造一起成为半导体产业的三大支柱。

In order to look for the path of the complement and the perfect our country legal person space system, oneself draw up the realistic demand to the present condition of the company law personality and the company law personality denial system, deny the system to the company personality to establish in the our country and possibilities and how establish to deny the system to carry on the study with the perfect our country legal person personality.

为寻求补充和完善我国法人格制度的途径，本人拟对公司法人格与公司法人格否认制度的现状，对公司人格否认制度在我国确立的现实需要性和可行性及如何确立和完善我国法人人格否认制度进行探讨。

After studying this case for six months we established the new system of salary and well-fare, of grade managing, of recruiting and training through the internal and external interview, making a diagnosis to the present personnel situation, and coming up with the solutions and thoughts to the problems, through imbuing of the reforming thoughts to the company, and adjusting the organizing structure and then to analyze and value works we done.

本案例历时6个多月，我们深入企业，通过内外部访谈，内部调研、外部调研相结合，通过标杆企业分析，完成了对企业现有人力资源管理状况的诊断，从中发现问题、找出差距、提供解决方案和思路；采用SWOT分析确定人力资源管理战略；针对企业新的战略目标和业务流程，采用&3PHR模型&，对组织架构进行了调整，重新设计了部门和岗位；通过工作分析、职位评估，建立了战略导向的绩效管理体系和薪酬福利体系。

Up to this present, lots of intensive researches have been done by domestic and overseas academicians, and the technology has been maturated.

至今为止，涉及的内容主要是结构性能对流动特性以及压力损失的影响，国内外已作了大量的透彻的研究工作，技术上已趋于成熟。

Along with the science and technology development, the networking popularization,the digitized technology will become now the science and technology development the front, the transformer substation digitization to further promotes the transformer substation synthesis automation level to get up to the limit the big promoter action, is the future transformer substation construction development direction.based on this kind of development demand, this transformer substation uses edcs-6200 the 110kv transformer substation synthesis automation.solves at present using the digitized technology to synthesize the automated transformer substation existence the question possibly to become.this transformer substation is causes the transformer substation using the digitized technology information gathering, the transmission, processing, the output process to digitize completely, and causes the correspondence network, the model and communication protocol unitizing, the equipment intellectualization, the movement management automation.

随着科学技术的发展，网络技术的普及，数字化技术成为当今科学技术发展的前沿，变电站数字化对进一步提升变电站综合自动化水平将起到极大促进作用，是未来变电站建设的发展方向。基于这种发展的需求，该变电站采用edcs-6200型110kv变电站综合自动化。利用数字化技术来解决目前综合自动化变电站存在的问题已成为可能。本变电站就是利用数字化技术使变电站的信息采集，传输，处理，输出过程全部数字化，并使通信网络化，模型和通信协议统一化，设备智能化，运行管理自动化。

It will be up to the Provincial Fr Gabriel Ngendakuriyo, to carry out preliminary investigations, and if these are convincing, to present the Rector Major with a formal request for introducing the Cause.

初步调查程序的进行，将视乎省会长 Gabriel Ngendakuriyo 神父的决定，假如有说服力的证据，他会向总会长作正式提出申请，展开封圣程序。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。