基于简谐激励的开槽圆盘粘弹性波导吸振器

在粘弹性变截面梁波导吸振器的基础上，研究简谐激励下的开槽圆盘粘弹性波导吸振器的耗能规律，定性地讨论了能量耗散率与粘弹性材料特性、开槽圆盘的几何参数及振动波频率的关系，并在家用冰柜压缩机上进行了减振试验。研究结果表明，开槽圆盘波导吸振器对低频振动具有良好的抑制作用。     

金属表面等离子体激发的实时场分布研究

利用时域有限差分法的电磁场仿真软件建立了金属-绝缘体-金属波导结构模型,并通过持续扩展光源激发该波导结构产生表面等离子体波,研究了金属表面等离子体激发的实时场分布.结果表明,表面等离子体波的各电磁场分量可以沿着金属-绝缘体的接触面传播,但传播距离有限,且垂直于接触面向两侧指数衰减.     

新型双弯曲磁过滤阴极真空电弧沉积系统的磁场模拟计算

本文用ANSYS软件对新型的45°双弯曲磁过滤阴极真空电弧沉积系统中的磁场分布进行了模拟计算,并结合等离子体传输和电弧源弧斑运行稳定性进行了分析。在建立的数学模型基础上,分别研究了磁过滤弯管磁场空间分布对拟定的不同出射方向上的111个碳离子束的传输行为影响,和外加永久磁体对电弧源附近磁场空间分布的影响。结果表明,在优化的磁过滤弯管磁场空间分布情况下,111个碳离子束流可全部通过磁过滤弯管,并高效传输到基材表面。当电弧靶源后部的外加永久磁体磁化方向与弯管上的磁化方向相反,且磁矫顽力大于600 kA/m时,阴极靶弧源附近的磁力线空间分布更利于控制阴极弧斑长时间运行稳定性,这对延长弧斑寿命、提高等离子体的沉积效率、提高靶材表面刻蚀均匀性和获得高性能的ta-C薄膜生长具有重要理论意义。     

空气声源激发的浅海声场的理论研究

研究了将空气中声速分布建模为Epstein分布,水层和海底均为均匀分布的三层介质模型的条件下,空气中点源激发的水下声场。既推导得到了声压场的形式解,通过数值分析,表明空气中点源激发浅水波导,在水层中形成的波导简正波具有实数本征值,可以远距离传播,称其为"水波"。空气层中的Epstein波导简正波在水层中为非均匀波,传播速度取决于空气中声速,称其为"水面波",并指出空气中声源运动产生的水面波多普勒频移大于水波多普勒频移。     

渐变折射率光波导模场分布的矢量FD-TD法分析

用二维矢量时域有限差分法分析了渐变折射率光波导中基模的模场分布情况，采用平面光波，球面光波，高斯光波等五种不同形态的光波激励同一波导，借助计算机进行数值求解，得到的光场分布图在光场传播达到稳定后完全相同，说明了波导的模式与光波形态无关，只与波导结构和光波波长有关，结果直观，精确，快速，并与解析法分析的结果相一致。     

非磁性建筑物空间磁场预测技术

提出了一种预测非磁性建筑物空间磁场分布的新技术．基于等效宏观磁导率和磁化率的概念，利用静磁场积分方程法的正演计算和反演计算技术，找出了试验模块磁场测量值与非磁性建筑物空间整体磁场之间的关系．通过试验模块测量和数学模型仿真相结合的手段，达到了预测低磁钢筋混凝土结构非磁性建筑物空间磁场分布的目的．     

离子交换波导折射率分布峰值的移动

本文提出利用表面等离子波共振(SPR)技术测量离子交换波导的表面折射率的方法.这种方法基于分析转移矩阵方法和表面等离子波技术,避免了传统方法中确定表面折射率的自由度问题,所以得到的波导表面折射率要比逆WKB法更为精确.用此方法研究了不同交换时间的样品,我们发现当交换达到一定的时间后,表面折射率会随交换时间的增长而下降,折射率分布峰值移向波导内部,说明这时存在一个银离子反扩散的过程,这与理论分析结论相吻合.     

中央开槽箱梁断面扭转涡振全过程气动力演化特性

中央开槽箱梁因其优越的颤振性能而在大跨度桥梁建设中得到应用,但中央开槽存在引发结构大幅涡振的气动稳定性问题。以典型大跨度桥梁中央开槽箱梁断面为对象,进行弹簧悬挂节段模型风洞测压、测振试验。对比研究了扭转涡振锁定风速全过程起振点、上升区中点、振幅极值点、下降区中点及涡振结束点等涡振发展过程箱梁表面气动力演化特性。研究表明,箱梁表面气动力在涡振过程不同阶段具有明显的变迁历程,气动力特性与涡振响应有明显的同步演化关系。分布气动力对涡激力的贡献与扭转涡振振幅呈正相关关系,均在振幅极值点风速达到最大,下游箱梁上下表面后部区域及上游箱梁上表面前部区域对涡激力贡献较大,前两者起增强作用,后者起抑制作用,这些区域的气动力是引起中央开槽箱梁扭转涡振的主要原因。与闭口箱梁上下表面下游分布气动力对整体涡激力贡献相互抵消效应相比,中央开槽使得下游箱梁上下表面分布气动力均对整体涡激力起增强作用,这是中央开槽箱梁相比闭口箱梁涡振效应更加突出的重要原因。     

实时磁钢表面磁场分布曲线测试仪的研制

磁钢表面磁场分布曲线的测量在磁钢生产中具有重要的意义.论文通过分析磁钢表面磁场分布曲线测试仪的功能需求,根据具体的应用特点,利用软硬件协同设计的思想,设计了测试仪的硬件平台以及控制软件,并且开发了上位机人机交互界面.整个测试仪已经用于具体的磁钢表面磁场分布曲线的测量中,提高了测量的效率和精度.     

基于磁记忆弱漏磁效应的钢绞线腐蚀检测

为明确缺陷对试件表面磁场的影响,该文对30Cr合金钢进行了逐级加载拉伸试验,在试件表面提前人为预制了缺陷,利用TSC-1M-4型磁检测仪采集磁场信号,研究了试件表面磁记忆信号在缺陷处的特征表现。切向磁记忆信号对试件的局部屈服更敏感。对其进行分析的结果表明：试件表面的磁记忆信号在缺陷边界处有明显的变化,通过表面磁场分布可以对试件的应力集中状况进行评价。     

立式锌锅高频磁场悬浮力和封流特性研究

本文采用专门设计的悬浮力和电磁封流实验装置，在铜、铝、锌高频磁场电磁悬浮力研究的基础上，讨论了电磁封流影响因素，得出了铜、铝、锌三种金属在固态和液态的不同工艺参数的影响规律，讨论了立式锌锅高频磁场电磁封流的可行性。     

电机槽楔用各向异性导磁复合材料进展

用各向异性导磁复合材料制备磁性槽楔是槽楔用导磁复合材料的发展趋势。本文综述了各向异性导磁复合材料的结构组成,并简要介绍了其相对于各向同性导磁复合材料所具备的特点,最后对目前各向异性导磁复合材料中存在的一些问题提出了看法和建议。     

磁悬浮运动平台的磁场分析及优化设计

研制了一种新型磁悬浮平台,该平台定子采用无铁心式的克莱姆绕组,消除了固有齿槽效应,动子采用Halbach 磁阵列结构方式,由于平台输出推力与悬浮的稳定性主要与其气隙磁场的分布情况有直接关系,因此提高气隙磁场的正弦分布是改善其工作特性的难点和重点. 为了改善气隙磁场的分布问题,提出了一个优化磁场分布的目标函数,并采用步长加速法对平台磁场进行了优化设计,大大降低了磁场谐波分量,改善了气隙磁场分布状态. 将优化结果运用到实际的平台中,对该运动平台进行了阶跃响应实验,实验结果表明满足平台需要达到纳米级精度的要求.     

Effects of the Slot Harmonics on the Unbalanced Magnetic Pull in an Induction Motor With an Eccentric Rotor

The slotting of electrical rotating machines creates slot harmonics of the air-gap magnetic flux density. These slot harmonics are the source of a nonnegligible part of the unbalanced magnetic pull (UMP). This paper presents analytical justifications for the use of a numerical impulse method to calculate the effects of the slot harmonics on the UMP. It uses the method to show that the force components due to the slot harmonics cannot be reduced easily.     

Magnetically induced vibration in a permanent-magnet brushless DC motor with symmetric pole-slot configuration

The paper reports a numerical and experimental study of magnetically induced vibration associated with rotor/stator eccentricity and imperfect magnetization for 8-pole 6-slot symmetric brushless dc (BLDC) motors. Magnetic forces and cogging torque are calculated for various slot angles by using the finite-element method (FEM). The results show that there is an optimal slot angle for minimum cogging torque, but this slot angle is not optimal for reducing magnetic forces. In the idle acoustics test, the motors with reduced magnetic forces show clear reduction at the expected frequencies while the motors with minimum cogging torque show no change at the cogging torque frequency, which implies unbalanced magnetic forces have greater effect on actual vibration of the spindle motor than cogging torque. The results show that the proper direction in motor design is to reduce unbalanced magnetic forces when both cogging torque and unbalanced magnetic forces are not achievable simultaneously.     

Optimal Slot Numbers for Magnetic Noise Reduction in Variable-Speed Induction Motors

Although many empirical rules have been established for correctly choosing the number of stator and rotor slots so as to limit the audible magnetic noise level radiated by induction machines, these rules never take into account the stator natural frequencies or the fact that the motor is run at variable speed. In this paper, we present a fast simulation tool for the variable-speed magnetic noise emitted by induction machines, based on fully analytical models. On the basis of these models, we derive and experimentally validate an analytical expression for magnetic vibrations due to slotting reluctance harmonics, confirming the prime importance of slot combination in magnetic noise radiation. We ran simulations on a 700-W squirrel-cage motor in order to quantify the noise emitted by all possible combinations of slot numbers in two- and three-pole pairs, including odd slot numbers. We thus obtained a database that efficiently replaces the old empirical rules for slot combination numbers and helps in designing quiet induction motors. Similar databases can be built for other power ranges.      

Influence of Slot Defect Length on Magnetic Flux Leakage

A key issue, which influences the applications of magnetic flux leakage testing, is defect quantification. There have been many research on the relationship between width, depth and magnetic flux leakage of slot defect. However, the length factor is often ignored. The relationship between characteristics of defect leakage field and defect length was investigated. The magnetic flux leakages of a series of plate specimens with the same width, same depth and different length slot defects were tested under the same magnetizing conditions. Testing results show that defect length is an important parameter needed to consider in quantifying defects.     

Multiple band-stop bow-tie slot antennas for multiband wireless systems

A novel and simple design of wideband coplanar waveguide (CPW)-fed bow-tie slot antennas with multiple band-stop characteristics featuring multi-network applications is presented. A frequency stop band can be created by embedding the slot with a pair of stubs, which causes the resultant magnetic fields almost counterbalance in the slot and to be non-responsive at the desire stop band. The effects of the dimensions of the stub on the stop band are also analysed. Dual band-stop characteristic is also accomplished by embedding two pairs of stubs in the slot. Details of the proposed designs and experimental results of the constructed prototypes are presented.     

Inspection of Local Wall Thinning by Different Magnetic Methods

The applicability of three different magnetic methods, Magnetic flux leakage technique (MFL), Magnetic adaptive testing and Metal memory method (MMM) was tested for detection of an artificial slot in a system of three steel plates. It was found that MAT resulted in the best signal/noise ratio, and it is capable to detect the bottom side slot even in the three layer configuration. MFL also resulted in acceptable signal/noise ratio in the two layer configuration, but it was not able to detect the slot through two other plates. MMM was not found to be suitable for unstressed and un-magnetized slot detection in the given experimental arrangement.     

Magnetic flow of viscous gas between rotating surfaces of revolution

In this work the steady laminar magnetic flow of viscous gas is considered in a narrow space (slot) between two surfaces of revolution rotating with constant angular velocities around a common axis of symmetry. The linearised equations of magnetic motion of the viscous gas flow for axial symmetry in the intrinsic curvilinear orthogonal coordinate system $\text{x, φ, y}$ are used. The obtained solutions of the equations of motion have been illustrated by examples of gas flow through the slot of constant thickness between rotating and fixed conical surfaces, and between rotating and fixed spherical surfaces.