混合磁轴承磁场与磁力解析计算

为克服传统线性近似法的不足,采用积分法计算一种新型混合磁轴承的气隙磁阻,在此基础上得到气隙磁场分布及转子所受磁力的解析解,并将计算结果与线性近似法计算结果进行比较。将上述两种方法对气隙磁场分布的计算结果与有限元计算结果进行对比,结果表明积分法计算结果与有限元计算结果非常吻合,而线性近似法误差较大。线性近似法计算气隙磁阻和磁力的误差大小与转子位移大小和方向有关,尽管磁阻误差较小,但磁力误差在12%以上。积分法可以有效提高气隙磁阻、磁场分布和磁力的计算精度,为磁轴承分析与设计提供有力依据。     

磁悬浮飞轮用新型永磁偏置径向磁轴承的设计

分析了一种磁悬浮飞轮用新型永磁偏置径向磁轴承的工作原理,利用等效磁路法对该永磁偏置径向混合磁轴承进行了分析,提出了基于位移刚度以及电流刚度的永磁偏置径向混合磁轴承的设计方法,给出了具体的设计步骤和设计实例.理论分析表明,所提出的方法与现有的设计方法相比考虑了磁轴承电磁参数与控制器参数的关系,设计结果与试验结果基本吻合.设计与试验结果表明:提出的设计方法切实可行,具有一定的应用价值.     

基于磁场梯度测量的磁记忆试验

金属磁记忆检测是无损检测领域的新技术。为探索以磁场梯度为判据的磁记忆检测方法,采用自制的专用磁场梯度检测仪,在地磁场环境对棒状低碳钢进行拉伸试验。结果显示磁场梯度与应力的关系随测量方法不同有很大差异。当将试件原位放置在拉伸机上测量时,磁场梯度与应力之间没有确定的关系;当将试件从拉伸机上取下测量时,磁场梯度与近期曾经受到的最大应力成线性关系。通过测量铁磁性构件表面的磁场梯度,为非破坏性测量应力提供新途径。另外,磁记忆信号会随试件取下后搁置时间而逐渐减弱的事实,表明用金属磁记忆技术检测应力集中具有时效性。     

新型磁流体密封圈的仿真及试验研究

采用对永久磁铁进行径向充磁的方法设计了新型磁流体密封圈,介绍了新型磁流体密封圈的结构和工作原理,利用磁场有限元分析方法对采用径向充磁和轴向充磁的磁流体密封圈的磁场分布进行了分析,给出了磁流体密封圈的磁场分布图,进行了耐压能力的估算及特性的仿真研究,并分别对两种密封圈进行了试验研究,对采用一级、二级、三级磁极的磁流体密封圈进行了试验比较,给出了试验曲线和仿真计算曲线。试验结果表明,永久磁铁采用径向充磁的磁流体密封圈比采用轴向充磁的磁流体密封圈结构简单,体积小,耐压能力高。     

基于阻尼粒子群优化的地磁场测量误差补偿

针对三轴磁力仪在磁场测量过程中的磁干扰问题,提出了基于阻尼粒子群优化算法的磁测误差补偿方法。建立了磁力仪误差和载体磁干扰的一体化误差补偿模型,分别采用阻尼粒子群算法和Two-step方法对非线性观测模型进行参数估计。以质子磁力仪数据作为真值,借助无磁转台充分连续采样,实验结果显示,阻尼粒子群算法对于磁场测量误差具有良好的抑制作用。补偿后,由阻尼粒子群算法和Two-step方法得到的均方根误差分别由1 025.7降至60.304 4、581 n T。结果表明,阻尼粒子群算法取得了更好的补偿效果,补偿精度提高了至少一个数量级,为磁场测量误差提供了一种非常有效的补偿方法。     

Non-destructive Measurement of Magnetic Properties of Claw Pole

The magnetic properties of the claw pole have a direct effect on the output power of a generator Many methods can be used to measure these magnetic properties,each with its own advantages,but an important shortcoming is that all are destructive.In this study,a new non-destructive method to measure the magnetic properties of claw pole was proposed and a corresponding testing set-up was designed.A finite-element model was constructed to simulate the measurement process.Results proved that the measured magnetization-like curves had good agreement with the trend of the input magnetic curves and the effect of the positioning error in the measuring process could be neglected.To further validate the new method,seven types of claw poles of different materials subjected to different heat-treatment processes were forged and tested by both the new method and the conventional ring-sample method.Compared with the latter,the new method showed better consistency,relatively higher accuracy,and much stronger stability of measurement results;however,its sensitivity needs to be improved.The effects of material compositions and heat-treatment parameters on the magnetic properties of the claw pole were briefly analyzed.     

利用复合激励的无盲点管道裂纹漏磁检测新方法

管道是石油和天然气工业的重要组成部分,而轴向裂纹是管道安全运营的重要隐患。传统的漏磁检测技术(MFL)对管道中轴向裂纹的检测灵敏度不高,从而形成检测盲区。本文提出了一种利用复合激励的MFL检测新方法,可实现对轴向和周向缺陷的同步检测。首先,利用U型磁轭对管壁进行交直流复合磁化;直流磁化场直接作用于周向裂纹并形成有效的MFL检测信号,而交流磁化场则在管壁内形成垂直于磁化方向的均匀涡流场;当该涡流场受到轴向裂纹干扰时,将形成二次感生磁场的扰动,因此,新方法通过对管壁表面的漏磁场及二次感生磁场检测,同时获得周向和轴向两个方向的探测能力;最后开展仿真和实验,并分析了新方法中作用于轴向和周向裂纹的磁化场、涡流场和二次感生磁场的分布。结果表明,新方法只需通过一次扫描,即可以获得缺陷的轴向和周向特征,实现了对裂纹的无盲点检测。     

磁航向测量系统误差修正方法研究

介绍了磁航向测量系统的设计．分析了影响磁航向精度的误差来源及目前磁航向误差补偿算法存在的问题。在此基础上提出一种基于椭圆最佳二乘拟合的新算法．对现有的磁航向误差补偿算法加以改进。试验结果表明，该补偿算法在不以增加硬件复杂度和软件计算量为代价的前提下，能够很好地修正软硬磁场引起的磁航向误差，提高了磁航向测量系统的完整性与实用性。     

时栅的波动方程分析与行波形成新方法

分析时栅位移传感器运动坐标系的产生机理。为了简化时栅结构使之更易于产品化,在分析其波动方程的基础上,明确磁行波和电行波的联系与区别,进而提出一种新的行波形成方法以及相应的机械结构,从而构成一种新形式的时栅传感器。初步的试验结果表明,传感器产生出正确的电信号,证明此方法是可行的。至此摆脱了采用传统模式的运动磁场产生方法,加工工艺大大简化。     

MAGNETIC FIELD AND TEMPERATURE MEASUREMENTS WITH A MAGNETIC FLUID-FILLED PHOTONIC CRYSTAL FIBER BRAGG GRATING

A novel simultaneous measurement method for magnetic field and temperature is proposed based on the two-resonant peaks photonic crystal fiber Bragg grating (PCFBG) filled magnetic fluid. The measuring principles are introduced in detail and verified by experiments. Sensitivity coefficients were achieved theoretically and experimentally and found to be consistent. The errors of temperature and magnetic field sensitivities were indicated theoretically and experimentally. The measurement resolutions were given. The results show that the scheme is feasible. It solves the cross-sensitivity problem between temperature and magnetic field of the fiber grating sensor, realizes dual-parameter measurement using single fiber that reduces greatly the size of the sensing probe, and provides a new method for the two-parameter measurements.     

双传感器差分峰值侦测的漏磁检测新方法

为了提高管道、储罐漏磁检测的准确度、灵敏度,同时抑制噪声干扰,提出了一种双传感器差分峰值侦测的漏磁检测新方法。首先,对实际漏磁检测过程存在的背景噪声进行分析,研究了检测器振动、磁隙变化、磁轭泄漏等噪声源的共模特性;其次,利用缺陷漏磁场的分布特点构造了一种新型的差分侦测结构,该结构既可对噪声进行共模抑制,又可实现缺陷特征信号的差模提取;再次,依托磁偶极子模型,对所提方法的机理进行了分析,并讨论实现该方法所需要的约束条件及其检测灵敏度特性;最后,开展了仿真和物理实验,实验结果表明,该方法的噪声仅为传统X分量检测的5%,Y分量检测的26%,且检测敏感度提高了2倍。该方法为优化漏磁检测器结构、提高检测的可靠性及灵敏性提供了一个新的思路。     

New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness(Ra) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid solidification presented can significantly improve the finishing performance and service life of magnetic abrasive, and provide a more practical approach for large-scale industrial production of magnetic abrasive.     

检测方向和提离值对磁记忆检测信号的影响

金属磁记忆检测技术是利用磁致伸缩逆效应对铁磁性构件进行检测的新技术,本文通过试验研究了构件的放置方向和探头的提离值对磁记忆信号的影响。试验结果表明:无论试样如何放置,其表面的磁场强度分布规律没有发生变化,水平放置时磁场强度信号最大,构件水平(或铅垂)放置时,检测面平行和垂直于地磁轴两个方向的磁场强度几乎相等。探头提离值的大小对磁场强度及其梯度均产生影响,但曲线峰-峰值的位置没有改变。据此得出:构件的放置方向和探头的提离值影响磁场强度的大小,但对应力集中区的判断不产生影响。     

Simultaneous magneto-optical Kerr effect and Sixtus-Tonks method for analyzing the shape of propagating domain walls in ultrathin magnetic wires

The controlled nucleation and propagation of magnetic domain walls in ultrathin ferromagnetic wires, such as nanowires and submicrometer wires, is extremely important for the development of new high performance magnetic domain wall logic devices. Therefore, it is equally essential to possess adequate advanced experimental investigation techniques in order to be able to achieve a comprehensive in situ analysis of as many as possible parameters related to the domain wall propagation, e.g., wall shape besides wall velocity and position. In this paper, we report on a method developed specifically for the investigation of the shape of propagating magnetic domain walls in ultrathin magnetic wires, i.e., with the diameter of the magnetic wire in the range 100-950 nm. The newly developed experimental method is based on the simultaneous use of two full-fledged experimental techniques: the magneto-optical Kerr effect for analyzing the surface effects of the passing domain wall and the Sixtus-Tonks method for the investigation of the entire moving wall. The results obtained offer essential information about the shape of the propagating magnetic domain walls, being unique to this new method.     

采用粘结法的磁性磨粒制备工艺及实验研究

现有的粘结法制备工艺存在混合不均等问题,且磁介质相和磨粒相在破碎过程中会发生分离,易造成浪费,为此,提出了一种新的粘结法磁性磨粒制备工艺。在相同条件下,运用两种不同工艺分别制备了两种磁性磨粒,并进行了实验研究。采用扫描电镜、三维超景深显微镜观测试件表面,并用电子天平测试试件光整加工前后的质量变化。实验结果表明,采用新粘结法工艺制备的磁性磨粒对试件进行光整加工10 min后,表面粗糙度值Ra从0.800 μm减小到0.076 μm,材料去除率的最大值为0.67 μm/min。与现有粘结法工艺制备的磁性磨粒相比,新粘结法制备的磁性磨粒的微观结构良好、各成分分布均匀,加工性能更加优异。     

基于椭圆约束的新型载体磁场标定及补偿技术

在地磁导航中进行地磁测量时会受到载体磁场的影响,因此必须对测量数据中的载体磁场进行精确补偿,以提高磁场测量精度.本文根据硬磁材料磁场和软磁材料磁场的数学模型,提出了一种基于椭圆约束的载体磁场标定及补偿方法.该方法首先采用带椭圆约束的最小二乘拟合方法对捷联式磁传感器测量数据进行椭圆拟合,保证了拟合曲线必为椭圆,从而实现载体磁场的准确标定,然后利用标定参数实现对载体磁场的精确补偿.最后进行了一系列的仿真试验.试验结果表明了该方法具有简单快速,易于实现的特点,可以达到与磁传感器等精度的补偿效果,且在低信噪比情况下具有较强的鲁棒性     

Calibration of the IZMIRAN Spectromagnetograph

The method and devices for calibrating the new IZMIRAN spectromagnetograph with a polarization analyzer of the fully parallel type are presented. A through-calibration algorithm is described that helps obtain the Stokes matrices for each pixel of a CCD camera with allowance for the entire stack of optical elements. Problems of considering the background and aberrations are analyzed. The results of test measurements of magnetic fields and line-of-sight velocities of an active region are presented.     

Magnetic fluid grinding of advanced ceramic balls

A new method of finishing advanced ceramics, namely, magnetic fluid grinding with a float, has been developed especially for Si₃N₄ balls. The removal mechanism in this process and the optimum grinding conditions have been studied in the last seven years. In this paper, the results from the published papers are surveyed and summarized from the viewpoints of removal rate, surface roughness and sphericity of balls. From this review, it was found that magnetic fluid grinding can be applied to the rough finishing process at high speed. However, if a sphericity smaller than 0.1 μm is required, some new ideas are necessary.     

基于气隙磁场分层耦合的直线时栅位移传感器研究

针对前期研制的电磁式直线时栅位移传感器高信噪比和高时间插补分辨力难以兼顾的问题,设计了一种提高传感器信噪 比的新传感器结构,另外提出了一种高信噪比、高时间插补分辨力的测量新方法,并研制了基于气隙磁场分层耦合的直线时栅位 移传感器。 建立传感器气隙磁场数学模型,分析气隙磁场空间分布特性,研究平面线圈气隙磁场分层耦合的原理;根据气隙磁场 分层耦合原理,建立传感器气隙磁场分层耦合位移测量模型;对传感器测量模型进行电磁场仿真和误差分析;最后,搭建实验平台 进行对传感器的性能进行测试。 实验结果表明,采用气隙磁场分层耦合的结构提高了传感器的信噪比,传感器的测量精度在原有 的基础上提高了 31. 4% ;采用的高信噪比和高时间插补分辨力测量方法,传感器的测量精度在原有的基础上提高了 37. 3% 。