磁偏转线圈行包电感的计算

本文报道了磁偏转线圈行包电感(以及由此形成的“储能”)的一种新的计算方法。该法非常准确且适用于普通线圈的设计,它是根据通过线匝的磁通匝数直接计算出电感的。实验发现,两只偏转线圈的电感计算值跟测量值极为一致。     

单绕组磁悬浮开关磁阻电机结构优化设计

针对单绕组磁悬浮开关磁阻电机结构参数的优化问题,提出了基于相关向量机与混合粒子群优化的方法。通过有限元分析计算了电机悬浮力和转矩与结构参数的关系,构建基于相关向量机非参数模型。以电机平均悬浮力和平均转矩最大输出为优化目标,采用混合粒子群优化算法获取最优结构参数,通过对比仿真实验说明了该算法的准确性与优越性,电机性能得到明显提升。     

磁悬浮径向轴承的三维有限元分析

应用ANSYS 10.0软件对磁悬浮径向轴承进行三维有限元仿真与计算分析,得出磁悬浮径向轴承磁力线、磁感应强度和电磁力在轴承中的分布.最后根据磁轴承线圈的两种绕线方式分析其磁场,并据此分析径向磁力轴承的几个特点,为径向磁悬浮轴承的优化和控制系统的设计提供了一定的依据.     

利用混合模型法计算微带天线间互耦

基于微带天线的传输线模型和空腔模型，提出了一种计算微带天线间互耦的新方法。在本方法中，首先根据腔模法原理，将微带天线等效为相距半波导波长的两个辐射缝隙；然后分别利用微带天线的传输线模型以及微带天线边缘面上的等效磁流分布求出微带天线的自阻抗和互阻抗，并进一步计算微带天线间的耦合系数。最后，利用本文方法编写Matlab程序求解矩形微带天线间的互耦，并与实验进行对比，比较结果验证了方法的高效性和可靠性。     

填平圆波导截止波长的计算

本文介绍了两种填平圆波导截止波长的计算方法:等效面积法和微扰法。并且对这两种方法作了说明和对比,通过讨论它们的适用范围,并结合已有的实验数据得出了填平圆波导归一化截止波长的计算曲线。     

填平圆波导截止波长的计算

本文介绍了两种填平圆波导截止波长的计算方法，等效面积法和微扰法，并用对这两种方法作了说明和对比，通过讨论它们的适用范围，并结合已有的实验数据向出了填平圆波导归一化截止波长的计算曲线。     

考虑阴极斑点动态特性的真空灭弧室触头磁场计算方法研究

真空断路器广泛应用于中压电力系统中，利用触头线圈产生的磁场调控真空电弧是提高真空断路器开断能力的重要手段，然而目前的设计方法没有综合考虑阴极斑点动态运动与触头线圈磁场的耦合效应，影响其设计准确性和精度。本文建立了考虑阴极斑点与磁场耦合关系的触头磁场计算模型，根据阴极斑点分布计算触头间隙控制电弧的磁场，并由磁场推进阴极斑点运动。在四分之一匝线圈式触头下，分析了阴极斑点分布对触头磁场的影响，对比了考虑耦合关系对触头磁场计算结果造成的差异。仿真结果表明，在阴极斑点的初始扩散阶段，纵磁变化不明显，而横磁随阴极斑点扩散而变化；稳定燃弧时，考虑耦合关系与否的纵磁最大差值可达纵磁最大值的24.1%。本文所建立的模型以及计算方法为真空灭弧室触头提供了一种新的设计思路与方法。     

两种大距离徙动高分辨率星载SAR成像算法的性能比较

改进的CS算法和等效斜视的波数域算法是适用于大距离徙动高分辨率星栽SAR成像的两种算法。为了给算法的选择提供一些参考，本文对两种算法进行了性能分析和比较，给出了两种算法在成像精度、算法的适应性和运算量三个方面的特点，并利用大量的仿真实验验证了分析结果。     

一种利用顶点位形描述的任意正交折线线圈阻抗解析建模新方法

本文利用顶点位形描述方法,建立了任意正交折线线圈阻抗的封闭模型.首先,利用二阶矢量位公式对一个线形矩形线圈的电磁场分布进行描述,并推导了该矩形线圈的标量势表达式,其包含有一个利用矩形四个顶点的位置因子和角形因子进行描述的积分项;其次,证明了角形因子的两个重要性质,并利用该性质将矩形线圈的标量势表达式推广到任意正交折线线圈的情况;最后,建立了任意正交折线线圈阻抗的解析表达式,并以矩形螺线线圈为例进行了阻抗计算,并将计算结果与实验测量值进行了对比.结果表明,计算值与测量值之间有较好的吻合度.相对于现有的矩形描述法,本文所提方法在简化建模过程及提高建模速度方面具有明显优势.     

瞬变电磁测井同轴多匝线圈误差校正模型

受井眼尺寸限制,井下瞬变电磁系统通常采用同轴多匝接收线圈来改善探测性能.但是,线圈匝数的增加在提高信号强度的同时,也引入了模型失配误差.针对该问题,本文在柱状多层非均匀结构基础上,分析了接收与发射线圈间距对感应电动势的影响,并提出了一种瞬变电磁测井同轴多匝线圈误差校正模型.最后,不同收发间距的仿真结果表明,该模型可以有效校正多匝线圈模型失配误差,提高瞬变电磁测井反演精度.     

MEMS微电磁驱动器的分段磁路模型及实验研究

介绍了一种MEMS电磁微驱动器.基于分段磁路的网络方程法,针对微电磁驱动器所采用的平面线圈的结构特点,建立了平面线圈微驱动器的非线性磁路模型.实验结果表明,考虑线圈绕组半径不同而产生的磁动势分布效应可以为平面线圈型微驱动器建立可靠的模型.采用硅微细加工技术和微电铸技术成功地制作出了这种微驱动器,并对器件的性能进行了测试,测试结果表明,该模型能很好地计算驱动器的电磁力.     

Low-frequency dosimetry of inhomogeneous magnetic fields using the coil source model and the household appliance

In this paper, the magnetic field properties and the dosimetry at ELF (50 Hz) are investigated using a coil model, which is prescribed in the European standard EN50366 (CENELEC) as a substitute source model for real household appliances. The accuracy of magnetic field vectors and values of the induced current density, which is achieved with the coil model, were compared with the results of two test appliances (a drilling machine and a hand mixer) obtained from the equivalent source model. It was demonstrated that the magnetic fields obtained (dominant component and strength) using the coil model and the real appliance show an agreement with each other with a maximum difference of 5 dB. The calculated induced current densities in the numerical human body models (homogeneous and anatomical body models) and the real appliances also show a good agreement with each other with a maximum difference by a factor of 1.6 (by the anatomical body model). Furthermore, the values of both field vectors and induced current density values calculated using the coil model were shown to be higher than those calculated in the case of the real appliances. Based on these results, the applicability of the coil model prescribed in EN50366 confirms that of the two applied test appliances.     

生物组织电导率CMIT平面螺旋激励线圈的分析

计算了平面矩形螺旋线圈的电感值,结果与近似公式计算得出的电感值吻合。另外,通过理论计算发现,矩形平面螺旋线圈产生的磁场具有聚焦的特性,并计算和讨论了分层生物组织的电导率对电感的影响,认为用矩形平面螺旋线圈来做生物组织非接触的电导率成像的激励线圈是可行的。     

高频线圈坡面对生长FZ单晶的影响

通过对高频线圈下坡面对生长FZ单晶的作用,分析了不同坡面线圈的磁力分布,以及磁力在单晶生长过程中的作用.线圈下面坡度的大小,会产生分布不同的磁力,在FZ单晶生长时,磁力对固液交界面的外边缘有重要的影响.分析认为采用下坡度合适的加热线圈,可以有利于单晶的顺利生长,提高单晶的成功率.     

Analysis of efficiency of magnetic stimulation

Magnetic stimulation can activate excitable tissues noninvasively. However, this method requires high energy to operate and can produce equipment heat that leads to inefficient stimulation. In this study, a comprehensive optimization of efficiency for magnetic stimulation has been conducted. A total of 16 781 coil designs were tested in order to determine the optimal coil geometry and inductance for neural excitation. Induced electric fields were calculated to find the optimal stimulation site (OSS) of a given coil. The threshold energy of a magnetic pulse for neural excitation was then calculated based on the transmembrane responses of a nerve model. Simulation results show that there exists an optimal inductance, as a consequence of an optimal pulse duration, corresponding to a minimum threshold energy. A longer pulse width is required to obtain the maximum efficiency for axons with slower membrane dynamics, a longer coil-to-fiber distance, and greater values of resistance (R) and capacitance (C) of the resistance-inductance-capacitance circuit. The optimal geometry features a minimum coil height, suggesting a flat coil design for optimal efficiency. The dimension of the optimal coil design increases with the coil-to-fiber distance. Moreover, the cloverleaf design achieves the highest efficiency for infinitely long fibers whereas the butterfly design is optimal for terminating or bending fibers.     

磁场特性对光纤光栅波长磁调谐的影响

本文对光纤光栅波长磁调谐中的磁场特性作了定性的分析，提出了2种不同的磁调谐方法，并从理论和实验上加以比较，证实了用永磁铁和电磁线圈调谐的线性度优于用2个电磁线圈调谐；但在灵敏度方面，后者优于前者。     

Design and evaluation of a robotic system for transcranial magnetic stimulation

Transcranial magnetic stimulation is a noninvasive brain stimulation technique. It is based on current induction in the brain with a stimulation coil emitting a strong varying magnetic field. Its development is currently limited by the lack of accuracy and repeatability of manual coil positioning. A dedicated robotic system is proposed in this paper. Contrary to previous approaches in the field, a custom design is introduced to maximize the safety of the subject. Furthermore, the control of the force applied by the coil on the subject's head is implemented. The architecture is original and its experimental evaluation demonstrates its interest: the compensation of the head motion is combined with the force control to ensure accuracy and safety during the stimulation.     

Development of a high-speed solenoid valve-investigation of theenergizing circuits

The electrical circuits developed for the purpose of energizing the solenoid valve are examined. These circuits, called the dummy coil method, where energy stored in a dummy coil in the form of a magnetic field is transferred to an energizing solenoid, and the pre-energize method, where the solenoid is electrically energized in advance by taking advantage of the solenoid's attraction force characteristics, are discussed. The results of experiments show that the pre-energize method is highly effective in speeding up the operation of solenoid valves. These experimental results are discussed along with the results of calculations conducted using a mathematical model     

透射电子显微镜原位磁场双倾样品杆的研制

本文简述了透射电镜磁场双倾样品杆的设计方案,展示了Philips/FEI透射电镜磁场双倾样品杆的研制成果.利用该样品杆可以产生100 Oe的连续磁场,也可以产生140 Oe以上的瞬间磁场.通过“U”型磁组件和样品杯的巧妙设计,尽可能的减小了电子束在横向磁场中的偏移量.     

涡旋线圈解析建模的电磁补偿结构设计与应用

基于空间向量积分法建立了共轴涡旋结构载流线圈的解析模型,计算了磁场及磁力,并对特殊取值下的磁场空间分布进行了数值分析和讨论。基于仿真结果,提出线圈密绕情况下的近似模型并进行了相应的误差分析。结果表明,所提模型可有效地直接对磁场分布进行近似,但需对受力近似进行一定的补偿。