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Additional Reading
安装在有限大障板上的轴对称扬声器特性的近似计算方法
陆晓 [1], 温周斌 [1],
[1] 浙江中科电声研发中心，嘉善，浙江，中国
使用 COMSOL Multiphysics® 仿真轴对称扬声器一般可采用 2D 轴对称模型，但在这种坐标系下无法建立扬声器测量中常用的矩形障板模型，而选择计算安装在无限大障板上扬声器的声特性，其仿真计算结果又与常见的标准障板上的测量结果在中低频段存在较大差异。 为了使无限大障板上的仿真结果与标准障板（或其它有限大障板）上的测量结果相一致，提出一种方法，利用 COMSOL 软件的 Parameter Sweep 功能，通过多次进行 2D 轴对称的电磁场、结构力学和声学三场耦合的扬声器仿真计算及相应后处理，得到安装在有限大障板上的扬声器正前方的声特性。 采用该方法可在较短时间内比较准确地计算得到安装在任意形状的有限大障板上的扬声器的声压级和谐波失真等特性。如图1和图2所示，采用该方法得到的声压级和总谐波失真曲线（红色），与测量结果（黑色）趋势和细节都比较一致。 ...
Analysis of an Inductive Proximity Sensor
A. Frey [1], I. Kuehne [2], R. Großmann [1], T. Frommelt [1], L. Fromme [3], T. Koch [4],
[1] Augsburg University of Applied Sciences, Augsburg, Bavaria, Germany
[2] Heilbronn University, Heilbronn, Germany
[3] Bielefeld University of Applied Sciences, Bielefeld, Germany
[4] COMSOL Multiphysics GmbH, Göttingen, Germany
Today, 90 percent of automation sensors are binary proximity detectors. Besides capacitive and optical types, inductive proximity sensors are essential for industrial applications. Compared to their mechanical counterparts, they offer almost ideal properties as contact-free and wear-free working principle as well as high switching frequency and precision. Inductive sensors cover a detection ...
Calculating Impedance of a Common Mode Choke in High Frequency Regime
J. Lin [1],
[1] Pitotech Co. Ltd., Changhua City, Taiwan
Common mode chokes are good EMI filters in electronic power systems [1]. For such devices, values for their impedance are critical to their performances as noise filters. In this study, a two-step finite element approach is employed to study the impedance variations of a ferrite-core common mode choke operating at high frequencies (0.1 to 10 MHz) [2]. Extraction of inter-winding parasitic ...
Understanding Ferrofluid Spin-Up Flows in Rotating Uniform Magnetic Fields
S. Khushrushahi, and M. Zahn
Massachusetts Institute of Technology, Cambridge, MA, USA
A fully filled sphere of ferrofluid has constant demagnetizing factors in all three Cartesian directions such that when subjected to a uniform external rotating magnetic field the internal field is also uniform, and ultrasound measurements give no observable flow. Non-uniform magnetic fields or a non-uniform distribution of susceptibility are necessary conditions for ferrofluid spin-up flows in ...
Simulation of Sample Inhomogeneity in Microwave Impedance Microscopy
T. S. Jones [1], C. R. Pérez [1], J. J. Santiago-Avilés [1],
[1] University of Pennsylvania, Philadelphia, PA, USA
Microwave impedance microscopy (MIM) is a novel mode of atomic force microscopy that can measure topography and local electrical impedance simultaneously and with nanometer spatial resolution [1]. This technique is typically used qualitatively, identifying defects in nanodevices or imaging ferroelectric domain walls, for example. However, the technique also has the potential to be used in a more ...
Simulation of Flux Density in a Hybrid Coil SMES using COMSOL Multiphysics
S. Roy[1], G. Konar[1]
[1]Power Engineering Department, Jadavpur University, Kolkata, West Bengal, India
Energy storage is an essential component for hybrid power system using non-conventional energy resources. Batteries, compressed air energy storage, pumped hydro plants etc. have been developed for storage. However, these have demerits like losses involved in energy conversion and time delay. Superconducting Magnetic Energy Storage (SMES) can be a good alternative as it stores electrical energy ...
Three-Dimensional Modeling of Electrical Scanning Probe Microscopy Problems
G. Gomila [1], L. Fumagalli [2], R. Fabregas [3],
[1] Institut de Bioenginyeria de Catalunya (IBEC), Departament d’Electrònica, Universitat de Barcelona, Barcelona, Spain
[2] School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
[3] Institut de Bioenginyeria de Catalunya (IBEC), Universitat de Barcelona, Barcelona, Spain
Electrical scanning probe microscopy (SPM) techniques, such as electrostatic force microscopy, nanoscale impedance microscopy or scanning near field microwave microscopy, are a relatively new branch of microscopy techniques that can generate images of the nanoscale electrical properties of samples (conductivity, permittivity, charge, etc.). These techniques scan the surface of a sample ...
Accuracy Assessment of The Linear Induction Motor Performance using Adaptive FEM
M. Manna[1], S. Marwaha[1], and C. Vasudeva[1]
[1] Department of Electrical & Instrumentation Engineering, Sant Longowal Institute of Engineering and Technology , Longowal (Deemed University), Punjab, India
The majority of electrical machines are designed to produce the rotary motion, there by exploiting the blessing of circularity which man has enjoyed since the discovery of the wheel. Electromagnetic forces may also be employed to produce the linear motion resulting in linear motion electrical machines. The performance of a high speed LIM is severely degraded by "End Effects". The paper ...
Electrophoretic Focusing and Navigation for Intranasal Target Drug Delivery
X. Si[1]
[1]Calvin College, Grand Rapids, MI, USA
Direct nose-to-brain drug delivery circumvents the blood-brain-barrier and has multiple advantages over intravenous delivery. However, its application is limited by the extremely low delivery efficiency to the olfactory region. This study evaluated the feasibility of targeted drug delivery with electrophoretic forces in a 2D human nose model. COMSOL Multiphysics® AC/DC, CFD, and Particle Tracing ...
Multiple Solutions in the Theory of DC Glow Discharges
P. Almeida, and M. Benilov
Departamento de Física. Universidade da Madeira, Portugal
It was suggested long ago that a theoretical model of a near-cathode region in a DC glow discharge admits multiple steady-state solutions describing different modes of currrent transfer. Even the most simple self-consistent models should admit such multiple solutions. In the present work, these solutions have been calculated for the first time with COMSOL Multiphysics.