熔体的定向受迫流动对高纯A1柱状晶生长特征的影响

研究了在离心力场和电磁场作用下融熔高纯Ａ１的凝固现象。研究结果表明，在二种力场共同作用下，产生的熔体定向受迫流动对柱状晶的生长方向和形态有很大影响，柱壮晶朝向迎流一侧发生倾斜，并随着离心转达和磁场强度的增加，柱状晶细化，倾斜角度增加。首次利用柱状晶间层流边界层理论解释了这一现象。     

TC4钛合金与LD10铝合金感应摩擦焊接头的组织与性能

利用感应电磁场对焊接过程热与物质流动作用,改善异种金属摩擦焊接头的组织与性能。采用光学金相、扫描电镜及室温拉伸实验与对比分析的方法,研究了外加电磁场对弱磁性材料TC4钛合金与LD10铝合金摩擦焊接头焊合区的显微组织、主要合金元素扩散行为及室温力学性能的影响。结果表明:外加电磁场作用使TC4钛合金与LD10铝合金摩擦焊接头铝合金侧动态再结晶区宽度增大;同时,感应电磁场通过影响摩擦副合金材料内部电子密度状态等,促进了摩擦焊接过程中主要合金元素Al和Ti在焊合区的扩散过程,并且提高了TC4钛合金与LD10铝合金摩擦焊接头的拉伸强度。其中,外加电磁场在顶锻保压阶段的影响更为明显。     

COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE ELEMENT METHOD

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.     

车载PEPS低频自动标定系统

针对车载PEPS系统的低频发射场实测问题,设计了一套汽车电子设备电磁场自动标定系统.该系统控制三维机械臂实现自动行走将场强测试仪送到指定测试点并记录场强值,然后通过可视化技术实现了电磁场强的三维分布显示.设计的标定系统实现了对PEPS系统低频发射场高效而精确的标定,为深入研究PEPS系统电磁场分布特征奠定了基础.     

“电磁场与电磁波”与“大学物理·电磁学”的教学比较研究

通过分析高等院校电磁场课程和大学物理电磁学的教学目标和教学方法手段,结合理论授课经验,探索不同教学方法在"电磁场与电磁波"课程教学中的应用,为梳理二者的定位提高教学效果提供了思路。     

基于瞬变电磁法的电磁场矿藏解释仿真技术研究

将瞬变电磁法（Transient Electromagnetic Method,TEM）应用到布敦花铜矿矿区的解释中,首先需建立电磁感应模型,对瞬变电磁场中的二次磁场频率、时间特性进行分析,通过MATLAB软件进行程序编写,得出相应的特性曲线图。然后分别计算早、晚期视电阻率和全程视电阻率,得出瞬变电磁场在矿区变化时的视电阻率参数变化,得出相应的数据结论。最后,利用MATLAB的网格化函数,对数据进行处理,模拟出瞬变电磁场在铜区时的异常场变化,完成对矿区的解释。从结果分析可以看出,利用瞬变电磁法解释的结果比利用物探资料进行矿区解释的结果更简单、更精确。这样一来,既提高了工作效率,又提高了解释的准确率。     

Harvesting light with transformation optics

Transformation optics （TO） is a new tool for controlling electromagnetic fields. In the context of metamaterial technology, it provides a direct link between a desired electromagnetic （EM） phenomenon and the material response required for its occurrence. Recently, this powerful framework has been successfully exploited to study surface plasmon assisted phenomena such as light harvesting. Here, we review the general strategy based on TO to design plasmonic devices capable of harvesting light over a broadband spectrum and achieving considerable field confinement and enhancement. The methodology starts with two-dimensional （2D） cases, such as 2D metal edges, crescent-shaped cylinders, nanowire dimers, and rough metal surfaces, and is well extended to fully-fledged three-dimensional （3D） situations. The largely analytic approach gives physical insights into the processes involved and suggests a way forward to study a wide variety of plasmonic nanostructures.     

短切碳纤维电磁散射特性仿真研究

研究单根碳纤维的电磁散射特性,如何改善碳纤维的吸波性能,是碳纤维复合吸波材料的难点问题.为上述问题,提出用圆柱体模型模拟碳纤维,根据三维电磁场有限元(FEM)算法,当平面波激励时,采用四面体棱边元网格划分及辐射边界条件以及矩阵方程组的自适应迭代算法,在Ansoft HFSS仿真平台上模拟了碳纤维的电场散射特性,获得了单根碳纤维的电场散射图.结果表明,在合适的长径比范围内,碳纤维与人射波产生强烈的谐振,碳纤维的电导率、轴向和入射波频率对其电磁波散射均有重要影响.仿真结果对设计具有强吸波性能的短切碳纤维复合吸波材料具有参考价值.     

磁能驱动微型泵的性能实验研究

在电磁场驱动原理的基础上,设计并研制了一种磁能驱动的微型泵。微型泵包括进／出液管、扩散管／喷管、驱动薄膜、腔体、电磁线圈和永磁体。微型泵的整体尺寸约为Ф11mm×4mm,腔室半径为5mm,深2mm。利用正交实验方法,对微型泵的性能进行了测试。在电压为4V、驱动薄膜厚度为6μm、频率为5Hz方波脉冲的最佳实验条件下,微型泵的最大泵送流速约为0．21mL／min。     

HFSS8．5在微带缝隙天线设计中的应用

介绍了微带缝隙天线中的维瓦尔迪天线,并借助于Ansoft公司的HFSS8.5软件进行了精确设计,通过将设计值与实验值进行比较,结果吻合。可以看出用EDA软件设计较之于传统的天线设计方法具有的优势,对于工程设计人员具有指导意义。