查询词典 field magnet

Faraday's law is that when the flux in the conductor loop changes, it produces electromotive force in the conductor loop, and obeys to contour integral law , Maxwell Curl Theory is that when the magnetic intensity of a certain point in ether space changes, there produces electric field at that point in ether space, which is the field mutual production theory of "electric field produces magnetic field and magnetic field produces electric field" in the free space which everybody is familiar with, and it obeys differential law , Lorentz magnetic force is that when metal electrons cut magnetic lines, metal electrons forced by move along the conductor to form inductive current, in fact, it doesn't matter whether coil moves or magnet moves, only if there exists relative motion between magnetic field and conductor, metal electrons must cut magnetic lines, which is,"coil stills while magnet moves to the left" and "magnet stills while coil moves to the right" these two situations are the same, which both belong to metal electrons having cut magnetic lines.

法拉第定律指导体环路里的磁通量发生变化时，在导体环路上产生电动势，而且服从围线积分律；麦克斯韦旋度理论指以太空间某点的磁场强度发生变化时，在以太空间的该点产生电场，即大家熟知的自由空间里"电场生磁场与磁场生电场"之互生场理论，而且服从微分律；洛伦兹磁力指金属电子切割磁力线时，金属电子受力沿着导体漂移而形成感应电流，其实，无论线圈运动或是磁铁运动，只要磁场与导体存在相对运动，则金属电子必然切割磁力线，即，"线圈静止而磁铁向左运动"与"磁铁静止而线圈向右运动"这两种情况是一样的，都属于金属电子切割了磁力线。

The system was reassembled using a new 4K GM cryocooler with larger cooling capacities both at the first stage and the second stage. The magnet reached a field of 5. 1T central field. This reassembled system was a cryogen free superconducting magnet system.

用一级和二级制冷量都较大的GM制冷机组成了第二套磁体系统，磁体中心场到了5T，既没有使用液氦，也没有使用液氮，这一套系统是最新式的无液体制冷剂的超导磁体系统。

It may be neccessary to measure the peak inrush current and consult with motor manufacturer since field magnet demagnetization may occur.

由于磁极去磁可能发生，测量峰值涌入电流并和电机制造厂商进行沟通是必要的。谢谢各位！

The electric coil around a field magnet that produces the ''.

在磁场周围能够产生磁发电机原动力在电器内产生电流的线圈。

Objective:To assess the clinical application of MR urographywith low field magnet.

目的：评价低场磁共振泌尿系成像的成像技术的临床应用。

The profiles of the magnetic field intensity and magnetic acceleration in the concerned rooms of typical permanent magnet and superconducting magnet systems are presented, which may be helpful for the selection and design of the magnetic gradient field.

分析了典型永磁体和超导磁体工作空间内的磁场强度和磁加速度的分布规律，可为梯度磁场的选型和设计提供理论依据。

Third, The author analyzed the shimming method of the existing magnet system and programmed it. Because the base field homogeneity of the open magnet is worse and only passive shimming is available, it is necessary to study more effective shimming algorithm. The ordinary shimming method is based on the disintegration of the magnetic field using spherical harmonics. It is so tedious that involved in large scaled non-linear equations.

再次，详细分析了现有磁体系统的匀场方法，并通过编程运算，发现在开放型磁体这一特殊情况下，由于基场均匀度差和只能使用水磁材料垫补进行匀场等原因，基于对磁场分布用球谐函数分解并消去球谐函数高次项的常规匀场方法在实现上相当繁琐，牵涉到大型非线性方程组的求解，所以必须采用更有效的匀场算法。

A single D-shaped toroidal field magnet coil will be tested for large and expensive magnets systems before assembling them in the toroidal configuration.

超导磁体中变化的磁场被分解切向和法向两个分量，通过将超导线分为适当单元可求出磁场两个分量产生的涡流损耗。

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。

In MRI system, magnet system is the main part that generates imaging magnetic field. Its performance is an important factor to affect image quality. Therefore, the research on methods for magnet system has important theoretical and applied values. Magnet system is mainly composed of magnet and shimming component.

在磁共振成像设备中磁体系统是一个重要的组成部分，负责产生均匀静磁场，为磁共振成像提供基础物理环境，其性能的优劣是决定磁共振图像质量的重要因素，也是衡量整个成像系统性能的主要参考指标，因此具有重要的研究意义。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。