查询词典 radius

Quantum dots are a kind of semiconductor nanopaticles with the radius equal to or less than the exciton Bohr radius. They have tremendous potential in the field of biology and medicine because of their unique and tunable optical properties (broad excitation spectrum, narrow emission spectrum, precise tunability of their emission peak and negligible bleaching, etc) as new fluoresent probes.

量子点是半径小于或接近于激子玻尔半径的一类半导体纳米晶，作为一种新型的荧光标记物，其独特和可调谐的光学特性（宽的激发光谱、窄的发射光谱、可精确调谐的发射波长以及可忽略的光漂白等）使其在生物和医学方面显示出巨大的应用潜力。

In chapter four, we prove that a complete open Riemmannian manifold with Ricci curvature negatively lower bounded is of finite topological type provided that the conjugate radius is bounded from below by a positive constant and its excess is bounded by some function of its conjugate radius.

第四章，我们证明了对于Ricci曲率具负下界的完备开Riemannian流形，当其共轭半径有正下界且它的Excess被其共轭半径的某个函数所界定时，它就有有限拓扑型。

Radius of a bend: take the biggest radius of a bend of a cable, oil pipe, gas pipe or water pipe as a reference value and leave 10% of the space as a margin.

内宽：选择较粗的一些电缆油管气管水管等，其外径之和作为拖链内宽的参照，并留有至少10%的宽度空间。

Firstly , the following proofs are made by means of homothet-ic transformation : 1 the centre of a nine-point circle is at the midpoint of ligature of its curcumcentre andorthocentre; 2 the radius of nine-point circle is equal to half of the radius of its curcumcircle.

本文给出一个简单的证法，先用位似变换的方法证明九点圆的圆心在外心和垂心连线段的中点，九点圆的半径等于外接圆半径的一半。

Consider the circle that is tangent to the curve at and has the same curvature there. Its center will lie on the concave side of the curve. This circle is called the circle of curvature. Its radius is the radius of curvature, and

在点处的曲线的法线上，在凹的一侧取一点，使得，以为圆心，半径为的圆叫做曲线在点处的曲率圆，曲率圆的圆心叫做曲线在点处的曲率中心，曲率圆的半径叫做曲线在点处的曲率半径。

For example,we have the following simple result:Lei the Taylor series F =has a radius of convergence or 1, where 0 = If F is of order p (For the two cases of the radius of convergence,the meanings of "order"are different.).

如果这级数有级ρ(在收敛半径是∞或1时，"级"的意义不同)，那么在第一种情形。

A transfer-matrix method is used to study cylindrical wave reflection at cylindrical media interfaces. We find that the reflection can be total at an interface of small radius but is only partial if the radius is large.

应用转移矩阵法研究柱面介质内表面处柱面波的反射，发现在小半径内表面上的反射为全反射，当半径较大时，它只是部分反射。

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 radius is half of the diametre ,and the diametre is two times the radius.

半径是直径的一半，直径是半径的2倍。

Diamagnetic loop is new beam diagnostic technology, it measures electromagnetic parameter-magetic moment that is brought while beam is transforming, by measuring magnetic moment we can calculate beam radius. Diamagnetic loop is non-intrusive diagnostic system, it can diagnose beam radius on line and it can diagnose beam emittance and obliquity cooperating with other technology such as three gradient method and beam bugs.

反磁回路法是国际上近年来发展起来的一种新的束流诊断技术，它是通过测量束流传输过程中产生的电磁场参数对束流的特性——束流半径进行诊断的，是一种非阻挡型的诊断系统，可以在线诊断束流情况，与其它方法相配合还可以得出束流剖面的其它参数，具有结构简单、抗电磁干扰能力强、安装使用方便可靠等特点。

More than five decades after the Indian constitution promises a casteless society, there is no sign that the castes are disappearing.

在印度宪法允诺一个&无种姓&社会五十多年后，种姓尚没有显示出任何要消失的迹象，但变化也确确实实地发生了。

Don't distract him from his studies.

他在学习不要打扰他。