查询词典 axial field

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。

We proposed a set of tabulate shim coils to improve the imaging field homogeneity for permanent magnet. By studying the magnetic spherical harmonics and its Taylor expansion, the proposal of designing lower-order radial coils was derived including x, y, xz, xz~2, x~2-y~2 etc. In addition, a novel composite design was presented for the axial coils. By controlling the shim currents of axial coils, different axial magnetic fields can be obtained. This method simplified the design process of axial coils, and made the axial correcting magnetic field more precise.

本文针对永磁体的组成结构提出了一种平板式匀场线圈设计方法，通过研究成像磁场的球谐函数以及通电圆弧在自由空间产生磁场的泰勒展开级数，导出了x、y、xz、xz~2、x~2-y~2等低阶径向线圈的设计方法，同时针对轴向线圈提出了一种新的混合式设计方案，能够通过控制线圈中的电流组合实现对不同轴向磁场分量的获取，简化了轴向线圈的设计过程，提高了校正磁场的准确性。

The main contributions of the second part of this dissertation are focused on the cryptographic properties of logical functions over finite field, with the help of the properties of trace functions, and that of p-polynomials, as well as the permutation theory over finite field: The new definition of Chrestenson linear spectrum is given and the relation between the new Chrestenson linear spectrum and the Chrestenson cyclic spectrum is presented, followed by the inverse formula of logical function over finite field; The distribution for linear structures of the logical functions over finite field is discussed and the complete construction of logical functions taking on all vectors as linear structures is suggested, which leads to the conception of the extended affine functions over finite field, whose cryptographic properties is similar to that of the affine functions over field GF (2) and prime field F〓; The relationship between the degeneration of logical functions and the linear structures, the degeneration of logical functions and the support of Chrestenson spectrum, as well as the relation between the nonlinearity and the linear structures are discussed; Using the relation of the logical functions over finite field and the vector logical functions over its prime field, we reveal the relationship between the perfect nonlinear functions over finite field and the vector generalized Bent functions over its prime field; The existence or not of the perfect nonlinear functions with any variables over any finite fields is offered, and some methods are proposed to construct the perfect nonlinear functions by using the balanced p-polynomials over finite field.

重新定义了有限域上逻辑函数的Chrestenson线性谱，考察了新定义的Chrestenson线性谱和原来的Chrestenson循环谱的关系，并利用一组对偶基给出了有限域上逻辑函数的反演公式；给出了有限域上随机变量联合分布的分解式，并利用随机变量联合分布的分解式对有限域上逻辑函数的密码性质进行了研究；给出了有限域上逻辑函数与相应素域上向量逻辑函数的关系，探讨了它们之间密码性质的联系，如平衡性，相关免疫性，扩散性，线性结构以及非线性度等；讨论了有限域上逻辑函数各类线性结构之间的关系，并给出了任意点都是线性结构的逻辑函数的全部构造，由此引出了有限域上的"泛仿射函数"的概念；考察了有限域上逻辑函数的退化性与线性结构的关系、退化性与Chrestenson谱支集的关系；给出了有限域逻辑函数非线性度的定义，利用有限域上逻辑函数的非线性度与相应素域上向量逻辑函数非线性度的关系，考察了有限域上逻辑函数的非线性度与线性结构的关系；利用有限域上逻辑函数与相应素域上向量逻辑函数的关系，揭示了有限域上的广义Bent函数与相应素域上的广义Bent函数的关系，以及有限域上的完全非线性函数与相应素域上向量广义Bent函数之间的关系；给出了任意有限域上任意n元完全非线性函数存在性与否的完整证明，并利用有限域上平衡的p-多项式的性质给出了有限域上完全非线性函数的一些基本构造方法。

In general, the design work with traditional measures is done by hand, which cannot meet the needs of the technology and manufacture. So the author has developed a CAD hydraulic design software fit for lower specific speed axial flow runner, which is easily operated by users.The main research work of this paper is as follows:1 Analyzing the main reason of axial flow power station cannot work well under littler volume of flow in some season and putting forward an improving scheme, pointing out the characters of design under abnormal factors.2 Combined with the development of the industry in our country, the abnormal hydraulic design method of propeller turbine is discussed based on present literature, data and experiment results.3 Guided by the design method of software engineering, a suit of hydraulic design software of Lower Specific Speed Axial Flow Runner is programmed by the object-oriented programming language Visual Basic and a straightforward, concise and standard Windows human-computer dialogue interface is designed for the system, which makes the operation of the system very convenient.4 ActiveX Automation technology is adopted as the interface with AutoCAD and the hydraulic drawings are edited, modified by AutoCAD until hydraulic model drawings according with the demand of engineering practice are output.5 To resolve practice problem, the author has designed a lower specific speed axial flow runner for Duowa Power Station through an example.

论文的主要内容有：1 深入分析很多轴流定桨式水电站枯水季节小流量下不能发电的主要原因，提出减容改造方案，并指出超常规条件下的改造设计特点。2 结合国情及行业发展需要，参考现有资料、文献和前人的研究成果，进行低比转速轴流式转轮叶片水力设计方法的研究，对轴流式转轮叶片的奇点分布法水力设计进行了全面的探索，结合现代计算机技术，找到了一种针对特殊条件的轴流式转轮叶片水力设计方法。3 仔细比较多种AutoCAD二次开发工具后，结合本课题的特点，选用Visual Basic语言，综合应用软件工程的设计思想，进行低比转速轴流式转轮叶片水力设计软件的编制，为系统设计了直观、简洁和标准的Windows人机对话界面，便于用户操作；编程时在考虑到设计条件特殊性的同时，尽量做到程序的通用性，使之可用于解决同一类问题；另外，大部分程序还可移植到普通轴流式转轮叶片水力设计中，具有良好的适应性。4 利用ActiveX Automation技术与AutoCAD接口，对AutoCAD进行二次开发，在AutoCAD下实现水力图的自动生成和编辑，直至输出符合实际工程要求的木模图。5 通过算例，为多哇水电站设计了一个低比转速轴流定桨式转轮，解决其在枯水期小流量下不能发电的问题。

A washer has a body having an axis and provided with a first bearing face surface located at one axial side and adapted to cooperate with a nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with an object, at least one third turning resistant surface adapted to cooperate with a thread of the bolt, the body having at least one resistive point arranged so that when the nut is turned and turns the bolt the body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to the body of the washer an axial force which overcomes the at least one resistive point so that a portion of the body of the washer is allowed to be pulled axially when the bolt elongates.

一种放在螺帽与物体之间的垫圈，螺帽与螺栓螺纹连接，螺栓插入在包括两个装配的部件的物体内，垫圈具有主体，和设有第一支承面表面，位于一个轴向侧面和与螺帽配合，第二支承面表面，位于相对的轴向侧面和与物体配合，以及至少一个第三转动阻力表面，与螺栓的螺纹配合，从而使螺帽以给定的扭矩在一个方向转动同时垫圈的主体沿相对方向接收给定的力时，仅有螺帽转动，以紧固或松开螺栓，而垫圈的主体和螺栓保持静止。

The turbine comprises at least one radial or diagonal turbine stage (120) with radial or diagonal feed stream and axial exhaust flow and at least one axial turbine stage (121 - 125) with a axial feed steam and axial exhaust flow.

该涡轮机包括至少一个带有径向的或者对角线的入口和轴向的出口的径向的或者对角线的涡轮机级(120)和至少一个带有轴向的入口和轴向的出口的轴向涡轮机级(121-125)。

Based on theory and test, finally, the measurements which may reduce axial force are given, for example, strengthening the management of size and clearances in roll systems and maintenance of roll bearings, limiting rolling technological conditions, increasing the axial flexibility, releasing axial binding forces and establishing axial flexible lock mechanisms, etc.. So it provides the constructive suggestions for preventing from damage of roll bearings.

在理论分析和实验验证的基础上，分析了轧辊轴承的受力特点和破坏原因，提出了降低轴向力的对策，其中包括加强尺寸及间隙管理、限定工艺条件、加强轴承的维修与管理等&硬&性措施，以及增加辊系轴向柔度、施放约束、建立柔性锁紧机构等&软&性措施，为现场解决轴承损坏问题提供了建设性参考意见。

Thirdly, according to the development of the frozen soil, the coupling model of single freezing pipe of axial symmetry of temperature field, stress field and moisture migration is put forward firstly. Then, by means of the progressing principle of potential field, the coupling model of temperature field, stress field and moisture migration which is under the condition of the multi-freezing pipes is extended. At last, the energy balance equation, stress balance equation, quality balance equation, geometric equation, physical equation, initial and boundary conditions etc are adopted to give the analytic solution to the problem of plane axial symmetry of single freezing pipe.

第三，在对室内试验和现场实测结果研究的基础上，分析了土体冻结过程中温度场、应力场、水分场耦合原理，并按照冻土体形成发展过程，首先建立了单一冷源冻结轴对称温度、应力、水分场耦合模型；接着利用势场的迭加原理，将单一冷源情况的三场耦合问题推广到多冷源情况的三场耦合；最后根据能量守恒平衡方程、应力平衡方程、质量守恒平衡方程、几何方程、物理方程、初始及边界条件，解出了单一冷源平面轴对称问题的解析解。

A Rotary Arc Gap－switch in axial magnetic field is designed and built with high voltage, high current, large charge transfers, slight electrode erosion and long lifetime. The magnetic field, electric field distributions and move mechanism of the arc in axial magnetic field are studied.

为了满足高电压、大电流、高电荷转移量、电极烧蚀小、寿命长的要求，文中设计了一个由轴向磁场控制的旋转电弧间隙开关，研究了其电磁场分布及轴向磁场下电弧的运动机制，并进行了初步实验。

After take analyzed deeply for the opened magnet circuit with FEMM (Finite Element Method Magnetics) we find out the field distributing that is separated into three sections . One is the main area what we called as positive field section. Beside the main field there are tow areas that are called the inverted field sections. Loudspeaker arise a very serious distortion when the voice coil moving into inverted field areas. The direction of induced current in the coil part of entered inverted field area is same with the current driving into loudspeaker so that total currents increas largely and heat increase rapidly. With more coils moving into inverted area the voice coil will take on negative inductance properties. It is the main reason that voice coil is burned by heating with increasing current due to arise negative inductance. So opened magnetic circuit is not suitable for the woofers in which the voice coil have wider displacement range. When using this kind magnetic circuit design, the voice coil moving range should be less than the range of positive field to avoid loudspeaker arise serious distortion and heating. Even though voice coil moving range is in the positive area, loudspeaker will still arise more distortion because the field distribution is very cliffy at tow sides of the positive area and full range of magnetic field distribution is not parallel that will arise distortion. Base on above reasons, opened magnetic circuit is not an ideal magnetic circuit for low-frequency loudspeakers. But it can be used in mid-range or high-frequency productions.

开式磁路是由2片钕铁硼磁铁和主导磁板和导磁垫片组成，我们在实践过程中发现这种磁路结构不适合于低频扬声器的使用，我们通过使用FEMM（Finite Element Method Magnetics）软件包对该磁路进行了分析，该磁路的磁场范围被分成3个区域，其中在主导磁板附近形成一个正向磁场，在正向磁场的两边存在反向的磁场，音圈在工作时有很大一部分进入了反向磁场中，在反向磁场内线圈的感应电流方向与驱动电流方向相同，使得音圈呈现出负感抗特性，由于音圈的负感抗特性引起电流的增加导致音圈发热甚至烧毁，因此在扬声器中使用开式磁路时，音圈的运动范围应控制在正向磁场范围之内，否则音圈运动到反向磁场区域时将会产生很大的失真和发热，即使在设计时已经将音圈的运动范围控制在正向磁场范围之内，由于正向磁场的2个边缘磁场强度衰减太快，同时开式磁路中磁场的分布不是平行的，而是自由发散的分布，这样肯定会导致扬声器的非线性失真，因此我们得到的结论是：开式磁路并不是一个理想的磁路，它不适合于低频扬声器的使用，但它还可以应用于中高频扬声器。

Article 144 The Government of the Hong Kong Special Administrative Region shall maintain the policy previously practised in Hong Kong in respect of subventions for non-governmental organizations in fields such as education, medicine and health, culture, art, recreation, sports, social welfare and social

第一百四十四条香港特别行政区政府保持原在香港实行的对教育、医疗卫生、文化、艺术、康乐、体育、社会福利、社会工作等方面的民间团体机构的资助政策。原在香港各资助机构任职的人员均可根据原有制度继续受聘。

Small wonder, then, that the Chinese spend more in the shop than any other group of foreign visitors do .

这样的小惊喜，使中国顾客比任何国家的人消费得更多。