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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。
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It connects different factories or enterprises by the way of transmitting material flow or energy flow, to form industrial symbiosis networks by sharing the resource and mutual exchange by-products. Under this pattern,"by-product" of one producing process may be the raw material of another process. In order to explore material closed circular, energy conservation system and minimum discharge of the waste, it set up the circular pathway by imitating the natural circular system as"producer—consumer-- decomposer"in the industrial system.
它通过物质流或能量流传递等方式把不同工厂或企业连接起来,形成共享资源和互换副产品的产业共生组合,使一家工厂的废弃物或副产品成为另一家工厂的原料或能源,模拟自然循环系统,在产业系统中建立"生产者—消费者—分解者"的循环途径,寻求物质闭路循环、能量多级利用和废物产生最小化。
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This thesis contributes to geometry compression in the following aspects: Proposes a method of progressive spherical mesh parameterization based on local parameterization by directly projecting the deleted vertices to its neighborhood. Based on spherical mesh paramterization, an adaptive subdivision remeshing method by progressivly redistributing of sampling points is proposed, by this means, the main geometry information of the original mesh can be captured with only a small amount of samples, it can also be used in mesh simplification. By regarding attributes binded on mesh vertices as geometry signals and transferring them onto a uint sphere by means of spherical mesh parameterization, meshes with different attributes are compressed with spherical wavelet successfully with high compression rate. As a kind of lossy geometry compression technique, two mesh simplification algorthimes are also presented in this thesis.
归纳起来,本文的主要贡献有:提出了以直接投影局部参数化方法为基础的网格累进球面参数化方法;在网格球面参数化方法的基础之上,提出了一种基于累进优化布点方案的网格细分采样方法,该方法可以用很少的采样点就可以捕获到网格的主要特征,因此我们也将其用于后面的网格简化工作当中;通过将网格顶点上定义的各种属性看成几何信号,并以网格球面参数化为手段将几何信号迁移到单位球面上,从而成功地实现了用球面小波对各种几何信号的压缩;作为一种有损压缩方法,本文还提出了基于统一距离的网格简化算法和基于重采样的网格简化算法。
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It builds the whole liquid-cooling system mainly by the design of the liquid-cooling decalescence boxes(improve its bottom material from aluminium alloy to pure copper, enlarge its volume, better cooling effects, and strengthen pressurization), by the operations of cooling effect about the heat exchanger worked by its temperature adjustability of the ribs(diffuse the heat fleetly owing to the excellent diathermancy of the material of the ribs ,make effective diathermancy owing to ribs outside areas, and drive the heat of the ribs away by the fans), and by the water pump made up of the piezoelectric ceramic with the excellent performance-no electromagnetism interference, little cubage, little noise, light exterior, light weight, low consume, high flux, replacing the mechanical pump.
在液冷散热器的研究中,主要通过对液冷吸热盒设计不断地改进(使吸热盒底部的材料从铝合金变为纯铜材料,其整个体积有所变大,但其散热效果明显变好,且密封性得到了极大地加强),综合地运用换热器中肋片的壁面温度调节作用产生的散热效果(肋片材料优良的导热性,快速地扩散了热量:肋片较大的与流体接触的表面积,使传热更加充分,对流热阻大大减小;再利用风扇对肋片上的热量进行吹散),利用性能优良的压电陶瓷泵(该泵机电性能稳定,具有无电磁干扰、体积小、噪音小、外型轻薄、重量轻、低能耗。、高扬程等优点。)代替机械泵作为驱动源,搭建了整个散热系统。
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RESULTSdiabetic rats showed typical symptoms involving elevated serum glucose and weight loss (2)The rats in DM+VaD group reacted slower and made more error numbers in Y-maze than the rats in VaD group did, with a prolonged total reacting time in a whole day.(3)More neurons with serious damages, such as edema, ischemia or pyknosis could be found in DM+VaD group than in VaD group. More disarrangement of cone neurons, obvious glia proliferation, and more neuron apoptosis were found in CA area of hippocampus. CONCLUSIONS (1)2-VO in STZ-induced diabetic rats succeeded in establishing VaD animal models.(2) The cognitive dysfunction induced by VaD rats had been deteriorated by diabetes mellitus.(3)Morphology evidences proved that diabetes mellitus aggravated brain damages induced by VaD.PART II Effect of diabetes mellitus on the cholinergic nervous systemin CA1 area of hippocampus of VaDOBJECTIVE To estimate the role of cholinergic nervous system in hippocampus during the process of cognitive dysfunction aggravated by diabetes mellitus in DM+VaD group. METHODS Observe the changes of ChAT protein by immunohistochemistry stain. Chose three rats randomly from each group at each pointat two week, four week, and eight week, then sepa
经腹腔注射链脲佐菌素诱导慢性实验性糖尿病,1周后永久性结扎双侧颈总动脉(2-VO)制作VaD模型记录术后2周、4周和8周各组大鼠的体重及血糖;应用Y-迷宫检测空间定向学第二军医大学博士论文中…丈摘…要1ia;一色恤~﹁染澎糕行HE染色观察组织病理学孪叱;胶质细胞原纤维酸性蛋白protellZ,Cf冰尸标记观察星形胶质细舱的激活情况、橄声软公点娜育票票众糯黑橄居端粗默孺篇筑价井袱第二部分糖尿病对血管性痴呆大鼠海马c心区胆碱能神经系统的影响探讨海马CAI区胆碱能神经系统在糖尿病加重确D一大鼠认知障碍中所实验动物及分组同第一部分,应用免疫组织化学染色方法现察海马CAI{介狱牛第晕军l袭拔常博粗{论义
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Since the dismutation of superoxide radicals by SOD is a reaction that is rate-limited by diffusion and enhanced by electrostatic guidance, all these structural features may be related to GP-MnSOD's high catalytic activity: first, Lys38 may increase the effective enzyme-substrate association rate by enhancing the electrostatic gradient at its substrate channel; second, an excess of acidic over basic residues makes the negative surface potential of GP-MnSOD more larger than those of other known MnSODs. This may enhance the reaction rate by reducing futile collisions of superoxide radicals with GP-MnSOD's surface.
因此,GP-MnSOD的上述结构特征可能与GP-MnSOD的较高酶活有关:首先,Lys38增加了底物通道口的正静电势梯度,从而可能促进了GP-MnSOD的活性中心与底物的有效结合速率;其次,GP-MnSOD表面覆盖的过量酸性残基使得它比其它MnSOD在底物通道以外的蛋白表面更多地被负静电势所覆盖,这可能有效地减少了超氧阴离子与GP-MnSOD表面的无效碰撞,从而提高了反应速率。
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It is that:(1) the related compounds in Metronidazole Buccal Tablets prepared by Chongqing Medical College can be tested by determining (321nm) the total peak area of the impurities;(2) The related compounds in Metronidazole Disodium Phosphate for Injection prepared by Chongqing Medical College can be test by determining (254nm) the total peak area of the impurities and the peak area of the largest impurity;(3) Ceftriaxone polymer in Ceftriaxone Sodium for Injection prepared by Chongqing Keru Pharmacy Co.
结果如下:①用HPLC一UV法,在321nm处检测,用归一化法计算,控制各杂质峰面积的和,可检查重庆医科大学的注射用甲硝吟磷酸二钠中的有关物质:②用HPLC一UV法,在254nm处检测,控制杂质峰面积的和及控制最大杂质峰面积,可对重庆科瑞制药股份有限公司的注射用头饱曲松钠中的有关物质实施控制;③用HPLC一Uv法,在254nm处检测,按外标法计算,可检查注射用头抱曲松钠中的聚合物;④用紫外分光光度法,在277nm波长处测定吸收度,按C6H9N303的吸收系数为377计算每片标示百分含量,可测定重庆医科大学的甲硝哇口颊片的含量均匀度;⑤用紫外分光光度法,在277run波长处分别测定释放溶液20min、50min和90min的吸收度,按甲硝哇(C6H剥303)的吸收系数为377计算释放度,可检查重庆医科大学的甲硝哇口颊片的释放度。
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The research indicates that:(1) detecting λmax (277nm) can identify Metronidazole Buccal Tablets prepared by Chongqing Medical College;(2) detecting λmax (321nm) and λmin (265nm) can identify Metronidazole Disodium Phosphate for Injection prepared by Chongqing Medical College;(3) detecting tr (6.7min) in HPLC-UV spectrum can identify Ceftriaxone Sodium for Injection prepared by Chongqing Keru Pharmacy Co.;(4) detecting tR (10.2min) 6.7min in HPLC-UV spectrum can identify Clarithromycin Tablets prepared by Harebin Yida Pharmacy Co.;(5) detecting λmax (254nm) can identify Potassium Sodium Dehydroandroan Drographolide Succinate prepared by Hong Kong Yaohen Co..
结果表明:①测定紫外最大吸收波长λ_(max277nm可鉴别重庆医科大学医药研究所制备的甲硝唑口颊片;②测定紫外最大吸收波长λ_(max321nm和最小吸收波长λ_(min265nm可鉴别重庆医科大学医药研究所制备的注射用甲硝唑磷酸二钠;③测定HPLC-UV中的保留时间(t_R6.7min)可鉴别重庆科瑞制药股份有限公司制备的注射用头孢曲松钠;④测定高效液相色谱的保留时间(t_R10.2min)可鉴别哈尔滨伊达制药厂提供的克拉霉素片;⑤测定紫外最大吸收波长(又max254nm)可鉴别香港耀恒公司提供的炎琉宁。
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Shadow Play is a dramatic form which artistic effects are achieved by that the spectators watch the light shadow which is performed by plane puppet through a white screen; usually the plane puppet as well as the scene, properties and sceneries in the shadow play are leather products which are made by hand, by knife and colored drawing by folk artists, thus it is called shadow puppet.
皮影戏是让观众通过白色布幕,观看一种平面偶人表演的灯影来达到艺术效果的戏剧形式;而皮影戏中的平面偶人以及场面道具景物,通常是民间艺人用手工,刀雕彩绘而成的皮制品,故称之为皮影。
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Shadow Play is a dramatic form which its artistic effects are achieved by the spectators watching the light shadow that's performed by a paper-thin flat surface puppet through a white screen; usually the puppet as well as the backdrops, stage properties and sceneries in the shadow play are leather products which are made by hand, by knife and colored drawing by folk artists, thus it is called shadow puppet play.
皮影戏是让观众通过白色布幕,观看一种平面偶人表演的灯影来达到艺术效果的戏剧形式;而皮影戏中的平面偶人以及场面道具景物,通常是民间艺人用手工,刀雕彩绘而成的皮制品,故称之为皮影。
- 相关中文对照歌词
- In The Sweet By And By
- By Heart, By Soul
- By & By
- In The Sweet By And By
- By & By
- Piece By Piece, Frame By Frame
- Sweet By And By
- In The Sweet By And By
- By And By
- I Want To Be Loved By You (But Only By You)
- 推荐网络例句
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According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.
曝气设备的动力效率在叶轮转速为120rpm~150rpm时取得最大值,此时氧利用率和充氧能力也具有较高值。
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The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.
稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世,形体几无变化。
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When I was in school, the rabbi explained everythingin the Bible two different ways.
当我上学的时候,老师解释《圣经》用两种不同的方法。