查询词典 magnetic track

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。

Based on the analysis of displacement of the electron in transverse magnetic field ,computation of magnetic field of Helmholtz coil and the analysis of uniform scope of magnetic field,the expression of the electron displacement with magnetic field intensity in intensitive uniform magnetic field is modified by the authors.

为了衡量电子在横向磁场下的偏移量的实验中所测数据的优劣性，分析了电子在横向磁场下的偏移原理，，通过亥姆霍兹线圈全空间磁场的计算和磁场均匀性范围的分析；修正了电子在匀强磁场中偏移距离与磁感应强度的关系式，得到了电子在磁场中的偏移距离与产生匀强磁场的电流以及磁场大小的偏差率之间的关系以及成立的条件。

Dynamic magnetic therapy: combination of traditional Chinese medicine health study, use of modern magnetism of the latest achievements in overcoming the traditional static magnetic magnetotherapy all the disadvantages of making full use of dynamic alternating magnetic field, greatly increased the permeability of the magnetic field so that The role of magnetic field greatly increased the depth, combined with mechanical massage and physical therapy to achieve the role of three-dimensional.

动磁疗法：结合中医养生学，运用现代磁学的最新成果，克服了传统磁疗中静磁的各种弊端，充分利用动磁的交变场效应，大大增强磁场的渗透性，使磁场的作用深度大大增强，同时结合机械按摩，达到立体理疗的作用。

The results indicate that in the synchronizing condition the MRF is unyielded, every point of MRF in the flow field has the same angular velocity. Under the slipping condition, with the increase of magnetic field or the decrease of slip speed, MRF may transfer from whole yield to partial yield. When the MRF wholly yields, the angular velocity of MRF increases nonlinearly with its radius, the non-linear distribution becomes more obvious as the magnetic intensity in the working gap increases. When the MRF partially yields, the yield region expands with the decrease of magnetic intensity or the increase of slip speed and the unyield region always reaches the driven rotor. The transfer torque of MRTD increases with the increase of the external magnetic field, but the transfer torque maintains a constant value approximately with the variation of slip speed at the same magnetic intensity.

研究结果表明，在同步工况下，传动装置流场中磁流变液未屈服，各点角速度相同；在滑差工况下，随外加磁场的增大和滑差转速的减小，磁流变液逐渐从完全屈服向部分屈服转变；磁流变液完全屈服时，磁流变液角速度随半径呈非线性增加，工作间隙中磁场越强，流场的非线性分布越明显；磁流变液部分屈服时屈服区域随外加磁场的增大而减小，随滑差转速的增大而增大，未屈服区与主动转子相连；稳态下磁流变传动装置传递的转矩随外加磁场的增加而近似呈线性增大，但在相同外加磁场下，传递转矩基本不随滑差转速改变而改变，表现出良好的恒转矩特性。

Circular electric current is a classical physical model. The researches on the magnetic field distribution characteristics of the circular current are helpful for the further study on magnetic characteristics of magnetic dielectric. The ellipse electric current is a typical physical model of ring-like electric current. The researches on the magnetic field distribution of it make us obtain more understandings of magnetic problem of ring-like electric current.

圆电流是一个经典的物理模型，对圆电流磁场分布特性的研究有助于进一步研究磁介质的磁性特征；而椭圆形电流又是环形电流中一个典型的物理模型，对椭圆形电流磁场分布情况的研究，将让我们进一步认识环形电流的磁场问题。

The magnetic intensity of the applied magnetic force on a ferromagnetic material denoted by the term H measured in oersteds; b. The magnetic inducition or flux density as the flux per unit area normal to the direction of the flux ,denoted by B and measured in gauss; c. The magnetic permeability establishes the relation between magnetic induction and magnetizing force expressed as B/H =u; d.Residual magnetism or remanent magnetism which remains in the casting after the magnetizing force has been removed .

磁场强度的应用磁力就一铁磁材料标注由任期h来衡量， oersteds ；乙磁inducition或磁通密度为通量每单位面积正常的方向通量，标注由B和衡量在高斯；长该磁导建立的关系磁感应强度和磁化力表示的B /为H = u ； d.residual磁性或剩余磁性，这仍然是在铸造后，磁化部队已被删除。

The model of the outer layer hard and inter layer soft magnetic structure was suggested that the amorphous ribbon and wire are constituted by the relatively"hard" magnetic"shell"with relatively high magnetic coercivity and relatively"soft"magnetic "core"with relatively low magnetic coercivity.

非晶材料的尖锐脉冲电压现象是由于具有显著的不可逆壁移磁化过程导致大巴克豪森跳跃所造成的，脉冲的尖锐性与动态磁滞回线的形态密切相关，回线的方形度越高，则脉冲愈尖锐。

The article presents the developing condition of PWM and SVPWM first.Then the theory of SVPWM is discussed in detail.The SVPWM is based on the thought of magnetic chain tracking.It makes the ideal magnetic chain circle of three-phased sysmmetry electric motor supplied by three-phased sysmmetry sine wave voltage for basis,uses the practical magnetic chain vector formed by the different switch modes of three-phased inverter to track the basic magnetic chain circle.During the course of tracking,the inverter changes the switch modes properly to form the PWM waves.Then the modulation wave of SVPWM is analyzed in detail.The modulation wave of SVPWM is implicit,but the analogous modulation wave in A-B-C axis needs to be calculated in order to expose the internal relation of SVPWM and SPWM.That is to show the implicit modulation wave of SVPWM. SVPWM actually is a transformed SPWM ruly sampled by the modulation wave which is injected by the zero prefaces based on space vectors.

本文首先对脉宽调制技术的发展现状进行了综述，在此基础上分析了电压空间矢量脉宽调制技术的发展现状；接着对空间电压矢量脉宽调制技术的基本原理进行了详细的分析和推导，SVPWM是基于磁链追踪的思想，它以三相对称正弦波电压供电下三相对称电动机定子理想磁链圆为基准，由三相逆变器不同开关模式下所形成的实际磁链矢量来追踪基准磁链圆的，在追踪的过程中，逆变器的开关模式作适当的切换，从而形成PWM波；然后详细分析了电压空间矢量脉宽调制技术的调制波，虽然SVPWM法的调制波是隐含的，但是为了揭示SVPWM法与SPWM法的内在联系，需要求出SVPWM在A-B-C坐标系上的等效调制波，也就是将SVPWM的隐含调制波显化；SVPWM实质是一种基于空间矢量在三相正弦波中注入了零序分量的调制波进行规则采样的一种变形SPWM。

Considering the bit density of magnetic disk an order of magnitude higher than the track density for a long time, the track density of magnetic disk is the bottleneck problem in expanding the capacity of magnetic disk.

长期以来，磁盘的位密度一直比其道密度高一个数量级，大幅度地提高磁盘的道密度是制约磁盘容量提高的"瓶颈"问题。

A new mathematical model is put forward numerically to simulate the wheel ovalization.. In the numerical simulation, the dynamic model of a half railway vehicle coupled with a tangent track is employed. Using the new numerical method investigates vehicle-track coupling system dynamic responses including lateral and vertical displacement of wheelsets and the vehicle, lateral and vertical vibration acceleration of the track at different phase angle of the two side wheels of the same wheelset, which are compared with that of the traditional model. The numerical results show that the discipline and frequency of dynamic responses are accordant, amplitude and phase of lateral dynamic responses are different. It is concluded the traditional track geometric irregularity excitation model does not simulate the effect of periodic wheels ovalization on vehicle-track coupling system dynamic behavior truly, the new model is more accurate and reasonable.

本文研究了车轮二阶周期性非圆化—椭圆化，建立了一个新的模拟车轮椭圆化的数学模型，结合车辆－轨道空间耦合动力学模型，计算了同一轮对左右车轮不同相位和车轮椭圆度下轮对和车体的横、垂向位移，钢轨横、垂向振动加速度，并与传统模型计算结果作了对比，分析表明两种模型的动力响应变化规律和频率一致，但横向动力响应幅值和相位均存在不同程度不可忽略的差异，因此传统的轨道几何不平顺激励模型不能真实模拟车轮的周期性椭圆化对车辆－轨道耦合动态行为的影响，而本文模型更能反映实际椭圆车轮与钢轨接触情形，计算方法准确而合理。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。