Articles techniques et présentations

扬声器的失真问题一直受电声业界的关注，尤其是谐波失真，它是影响扬声器重放声音音质的主要因素之一。 本文提出了一种基于 COMSOL Multiphysics® 软件预测扬声器谐波失真的仿真分析方法。该方法需建立包括磁场、振动系统和声场等多个物理场的扬声器的全模型，给扬声器加载一单频电压信号，用瞬态分析的方法可求解得到该频率激励下的扬声器的多个重要物理量随时间的变化函数，如流经音圈的电流I(t)、音圈的受力F(t)、振动系统表面上任意点的位移x(t)，以及声场中任意点的声压P(t)等。给扬声器加载一个时间长度为0.1s的单频电压信号，仿真分析所得的防尘帽顶点的位移曲线 ... En savoir plus

The article deals with the application of the Hartmann effect in high power laser beam welding of aluminum. The movement of liquid metal in a magnetic field causes electric currents which build a Lorentz force that decelerates the original flow. The numerical model calculates the ... En savoir plus

3D-modeling of magnetic components with FEM is challenging due to the involved nonlinearities and coupling effects between different physical domains. A specific issue is the consideration of lamination due to the high resulting element count for thin layers. Therefore, several ... En savoir plus

Patch antennas are widely used in communications links with unmanned aerial vehicles. Their hemispherical send and receive patterns enable the systems to maintain radio frequency contact over a wide range of vehicular attitudes. A microstrip-fed design offers other attractive features ... En savoir plus

In this paper a multiphysics approach to study the optical properties of integrated waveguides influenced by thermal and mechanical stress is presented. The heating and pressure effects are evaluated by means the Heat Transfer and Structural Mechanics modules respectively. Finally, the ... En savoir plus

This paper presents the Finite Element Method technique for predicting performance of Induction motor having Electric and Magnetic asymmetry for rotor cage due to some broken rotor bars. The motor parameters like magnetic vector potential, flux density, surface currents have been ... En savoir plus

飞机燃油系统雷电防护是飞机设计中需要考虑的一个重要部分。用实验方法研究成本较高，且周期长，数值仿真方法具有明显的优势。本文基于COMSOL Multiphysics有限元仿真软件，建立内部带有液压管和燃油管的燃油箱系统模型。通过电-热耦合仿真考察雷电流在燃油箱上的传导路径，根据电流分布及温度分布给出成为潜在点火源的位置。进而对比研究了两端是否屏蔽对燃油系统上雷电流物理特性的影响。仿真结果表明：飞机燃油箱系统遭受雷击时，成为潜在点火源的位置有卡箍边沿、17号肋与燃油管和液压管连接处、燃油管和液压管以及桁条上距离16号肋和18号肋上开孔较近的地方 ... En savoir plus

VRALA is the ideal candidate as an Adaptive Optics actuator at visible wavelengths. Its electric characteristics variations, suitable current commands, and an effective magnetic circuit geometry provide a 2 kHz correction bandwidth and a 25 mm actuator density. The magnetic core allows ... En savoir plus

A specific issue in transformer modeling using the finite element method is the consideration of electric sheets or other laminated core materials which are used to reduce eddy currents. It would be impractical to explicitly model a large number of sheets as this would lead to a large ... En savoir plus

In welded tube manufacturing, the electric resistance welding (EW) process begins with a coiled plate of steel with appropriate thickness and width to conform the produced tube. The strip is pulled through a series of rollers that gradually cold conform it into a tubular shape. The edges ... En savoir plus