对比系数

The P-wave velocity-depth profile and electrical conductivity-depth profile can be calculated from the experimental data and the fundamental geothermal parameters in northern margin of the North China craton. The comparison of the calculated results with the elastic and electrical structure of this area reveals that the v of amphibolite is approximately equal to the middle crust, the electrical conductivity of amphibolite intersects the range of the middle and lower crust in this area.

利用实验获得的弹性波纵波速度及其温度系数和压力系数以及电导率与温度的关系，结合现今华北克拉通地热学的基本参数，计算得到斜长角闪岩的弹性波纵波速度－深度剖面和电导率-深度剖面，将二者分别与华北克拉通北缘深部地壳的弹性及电性结构进行对比的结果表明：高温高压下绿泥石化斜长角闪岩的弹性波纵波速度与该地区中地壳速度相当，电导率介于中、下地壳范围内。

Through numerical calculation and comparison with the complete formula,the accuracy of the approximate formula for calculation of reflection coefficient often used in AVA method for gas hydrate is discussed.

通过与完整公式的对比，对AVA常用的反射系数近似计算式的精度进行了讨论，同时分析了地震波速度、泊松比、密度等参数对于BSR反射系数的不同贡献。

PartⅡDiffusion-weighted MR Imaging of breast mass and non-mass lesionPurpose:To evaluate Diffusion-weighted MR Imaging of breast mass and non-mass lesion in lesion characterization by comparing ADCs of malignanty with benignancy.

第二部分磁共振扩散加权成像在乳腺肿块性病变和非肿块性病变中应用价值的对比研究目的：对比乳腺良、恶性病变的表观弥散系数(apparent diffusioncoefficient，ADC)，探讨DWI在乳腺肿块性病变和非肿块性病变中的诊断价值。

The pressure distributions around the circular cylinder in the numerical and experimental studies show quite a good agreement.

通过数值结果与实验结果的对比，对近壁绕流圆柱体的升力系数及其表面动水压力分布进行了研究，对比结果显示了较好的一致性。

The varying tendencies of partition coefficients of some compounds in aqueous or nonaqueous solvent systems by calculating the phase equilibria with universal quasichemical functional group activity coefficient model are predicted. These compounds included saturated and unsaturated fatty acids ethyl esters,N2,4dinitrophenylamino alcohols, pnitrophenyl glucosides and so on, with simple structures and much differences in polarity.

以饱和及不饱和脂肪酸乙酯、2，4二硝基苯胺基脂肪醇和对硝基苯基葡萄糖甙等结构较为简单、极性差别较大的溶质系列为研究对象，应用修正的通用基团活度系数模型，通过相平衡计算，预测了它们在含水或不含水的溶剂体系中分配系数的变化趋势，并与前人的工作进行了对比。

Considering that both the solution of the structure natural vibration frequency and mode as well as its elastic stability coefficient can transform into eigenvalue problem of the structure dynamic equilibrium equation, taking the fundamental frequency and the elastic stability coefficient of the structure as the evaluation criteria, the possible arrangements of Mi-brace and X-brace for halfthrough CFST arch bridge with 360 m span were comparatively analyzed, and the advices for the reasonable space of the Mibrace and the X-brace were advanced.

鉴于结构自振频率、振型及弹性稳定系数的求解均可转化为源自结构动力平衡方程的特征值问题，先以结构基频及弹性稳定系数为衡量标准，对一座360 m跨的中承式钢管混凝土拱桥可能的米字撑及X撑布置方案进行了分析对比，并据此提出了X撑及米字撑的合理间距。

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。

For another, madding use of methods of the multitude statisticalanalysis and the Euclidean distance analysis, Yeluyuzhi crania is 30compared with neoteric crania. The most resemble crania areMongolian crania, then the Korea crania, but with South China craniaand North China crania and Inuit crania, there are many differences.

在与现代亚洲蒙古人种的各近代对比组的比较中，本文运用了计算本文标本与各对比组之间欧氏距离系数和计算各对比组与耶律羽之组之间的组间差异均方根函数值的方法进行比较得出来的结果较为一致，即耶律羽之组男头骨在形态学上最为相似的是近代蒙古组，其次为朝鲜组，而该组与华南组、华北组及因纽特组之间则存在较大的形态差距。

Through the comparative analysis of the earth pressure calculated by the different calculation methods, it is known that when the earth pressure behind the abutment of the integral abutment bridge under the action of rising temperatures is calculated, it is not proper to use the m method to calculate the resistance coefficients of the abutment back wall and column earth while the resistance coefficient of the abutment back wall earth can be calculated by the Broms method. It is proper that the resistance coefficients of the earth of the abutment and pier piles should be considered by the p-y curve.

通过对不同方法计算的台后土压力的对比分析，得知：在计算升温引起的整体式桥台桥梁台后土压力时，桥台背墙及台柱土的水平抗力系数计算采用m法是不适合的；桥台背墙后填土的水平抗力系数可采用Broms法计算；土对台桩及墩桩侧的水平抗力系数按p-y曲线来考虑是适合的。

Single factor experiments were done with the factors including the width of protrusion and the trolley's velocity, which showed that the surface frictional coefficient decreases with the width of protrusion increasing, and doesn't change with the trolley's velocity changing, which was consistent with the results of the orthogonal experiment. A theoretical model of the horizontal projection of a corrugated bionic surface's contact area was built, which showed that the contact area's horizontal projection decreases with width and interval increasing respectively and that the ratio of the contact area's horizontal projection and the vertical load decreases with the vertical load increasing. It indicated that the surface frictional coefficient decreases with the above three factors increasing respectively. Finite element modeling and analysis of interactions of a plate and soils was done using ANSYS, which showed that the plate frictional coefficient is little relative to soil elastic modulus and decreases with vertical surface pressure and that trolley's pull and vertical displacement of bionic surface's control pilot keep constant almost during the plate being pulled. Finite element modeling and analysis of interactions of a corrugated bionic surface and soils was done using ANSYS, which showed that surface frictional coefficient is little relative to soil elastic modulus and decreases with bionic surface's structural parameters and vertical pressure increasing. However, the three factors all didn't affect the surface frictional coefficient remarkably on the condition of 90% dependability. For the first time, bionic surfaces were applied to screw piles, which formed bionic screw piles, and the contrast experiments showed the bionic screw pile had certain resistance-decreasing effects.

建立了波纹型仿生曲面与土壤的接触面积的水平投影的理论模型，表明接触面积的水平投影A随着波纹型仿生曲面突起宽度、两相邻突起间距的增大而减小，接触面积的水平投影与波纹型仿生曲面表面垂直载荷之比随着波纹型仿生曲面表面垂直载荷的增大而减小，进而得出仿生曲面摩擦系数随着波纹型仿生曲面突起宽度、两相邻突起间距以及表面垂直载荷的增大而减小；利用ANSYS软件对平板与土壤的相互作用进行了有限元建模与分析，表明平板摩擦系数与土壤弹性模量关系不大，而随着表面垂直载荷的增大而减小；平板牵引过程中台车牵引力和仿生曲面控制节点垂直方向位移基本保持不变；利用ANSYS软件对波纹型仿生曲面与土壤的相互作用进行了有限元建模与分析，表明波纹型仿生曲面系数在一定范围内基本不受土壤弹性模量的影响，随着波纹型仿生曲面突起宽度、两相邻突起间距以及表面垂直载荷的增大而减小，但在可信度为90％的前提下，三个因素影响都不显著；首次将波纹型仿生曲面应用于与土壤作用方式以挤压为主的螺旋桩，形成仿生螺旋桩，并与普通螺旋桩进行了沉桩对比试验，表明波纹型仿生曲面应用于螺旋桩桩体表面具有明显的降阻作用。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。