• Title/Summary/Keyword: Maxwell Equations

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Static behavior of thermally loaded multilayered Magneto-Electro-Elastic beam

  • Vinyas, M.;Kattimani, S.C.
    • Structural Engineering and Mechanics
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    • v.63 no.4
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    • pp.481-495
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    • 2017
  • The present article examines the static response of multilayered magneto-electro-elastic (MEE) beam in thermal environment through finite element (FE) methods. On the basis of the minimum total potential energy principle and the coupled constitutive equations of MEE material, the FE equilibrium equations of cantilever MEE beam is derived. Maxwell's equations are considered to establish the relation between electric field and electric potential; magnetic field and magnetic potential. A simple condensation approach is employed to solve the global FE equilibrium equations. Further, numerical evaluations are made to examine the influence of different in-plane and through-thickness temperature distributions on the multiphysics response of MEE beam. A parametric study is performed to evaluate the effect of stacking sequence and different temperature profiles on the direct and derived quantities of MEE beam. It is believed that the results presented in this article serve as a benchmark for accurate design and analysis of the MEE smart structures in thermal applications.

Transient Analysis of Induction Motors using Finite Element Method (유한요소법을 이용한 유도전동기의 기동특성 해석)

  • Kim, Young-Sun;Lee, Bok-Yong;Lee, Hyang-Beom;Lee, Ki-Sik
    • Proceedings of the KIEE Conference
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    • 1997.07a
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    • pp.306-308
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    • 1997
  • In this paper, We present the transient analysis method of induction motor by TDFE(Time Domain Finite Element) method. For simulation of transient performance, Maxwell's equations are solved using 2-Dimensional TDFE method, and the circuit equations from the stator and rotor are solved simultaneously. The time derivatives are discretized with Euler scheme and the Newton-Raphson iteration method is applied to a large system of equations which are representing the whole magnetic and feeding circuit equations because of the magnetic nonlinearity of the stator and rotor core. The presented method is applied to three phase induction motor. And we obtained the phase currents, torque and rotor position until the steady state.

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MODEL ON THE DYNAMIC BEHAVIOR OF CONDUCTIVE FERROMAGNETIC MATERIAL WITH NEGLIGIBLE COERCIVITY

  • Kim, Dac-Soo
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.790-794
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    • 1995
  • Differential equations governing dynamic behavior of toroid-shaped ferro-magnetic material having a small gap of uniform width were derived incorporating Maxwell equations of electromagnetic induction relevent to the system and Newtonian equation of motion. Once the external uniform magnetic field was applied within the material through dc-circuit around the toroid, gap begin to change which lead to the abrupt variation of field in the material and gap according to the differential equations already derived. Characteristics of current and electromotive force with respect to time in the circuit consisting of inductance and resistance in series could be predicted from numerical solutions of these equations. As current in the circuit increasesl, magnetic field in the material increases, thus, the gap starts to shrink due to increased attractive force between gap and elastic restoring force in the material. With an appropriate selection of elastic constant of toroidal ferromagnetic material and design of gap structure it is possible to obtain the specified in both linear and nonlinear magnetic characteristics, such as current dependent and independent inductance.

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Characteristics of MOSFET-Structured Silicon Field Emitter by Computer Simulation (전계 효과 트랜지스터로 제어하는 전계 방출 소자의 시뮬레이션에 의한 특성 평가)

  • Kim, Jin-Ho;Kil, Tae-Hyun;Yun, Sang-Han;Kim, Yong-Sang;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1318-1320
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    • 1998
  • We have investigated the electrical characteristics of a MOSFET-structured silicon field emitter by employing Maxwell 2D and Silvaco simulators. The potential distribution is obtained by Maxwell 2D simulator and the field emission current is calculated by Fowler-Nordheim equations. The characteristics of MOSFET is simulated by Silvaco simulator. Simulated results are almost identical to the experimental results. Also, we have studied the emission characteristics as funtions of several geometric parameters.

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Solutions of the Navier-Stokes equation in slip flow region (Slip flow 영역에서 Navier Stokes 방정식의 해석 연구)

  • Park, W.H.;Kim, T.K.
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.597-602
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    • 2000
  • In a MEMS(micro-electro mechanical system), the fluid may slip near the surface of a solid and have a discontinuous temperature profile. A numerical prediction in this slip flow region can provide a reasonable guide for the design and fabrication of micro devices. The compressible Navier-Stokes equation with Maxwell/smoluchowski boundary condition is solved for two simple systems; couette flow and pressure driven flow in a long channel. We found that the couette flow could be regarded as an incompressible system in low speed regions. For the pressure driven flow system, we observed nonlinear distribution of pressure in the long channel and numerical results showed a good agreement with the experimental results.

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Numerical Analysis of the Slip Velocity and Temperature-Jump in Microchannel Using Langmuir Slip Boundary Condition (미소채널내의 Langmuir 미끄럼 경계조건을 통한 미끄럼 속도 및 급격한 온도변화에 관한 수치해석)

  • Kim, Sang-Woo;Kim, Hyun-Goo;Lee, Do-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.164-169
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    • 2009
  • The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

Analysis of Excimer laser ablation via FDTD method (FDTD방법을 이용한 엑시머 레이저 어블레이션 해석)

  • Bae C.H.;Choi K.H.;Kim D.S.;Lee S.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.163-164
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    • 2006
  • In this paper, an analytical laser ablation model with Maxwell equation will be addressed by considering relationship between laser ablation and material. The Maxwell equation consists of four equations: two Gauss laws for electric and magnetic fields, Faraday's law, and Ampere's law. This analytical model will be calculated by employing Finite Difference Time Domain (FDTD). This method also makes it possible to simulate the laser beam propagation in a wide range of materials, such as metals, semiconductors, and dielectrics. Therefore, in this study, a numerical model for short pulse laser interaction with materials is developed, focusing on the accurate description of laser beam propagation and ablation process into the material with each pulse.

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Material model for load rate sensitivity

  • Kozar, Ivica;Ibrahimbegovic, Adnan;Rukavina, Tea
    • Coupled systems mechanics
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    • v.7 no.2
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    • pp.141-162
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    • 2018
  • This work presents a novel model for analysis of the loading rate influence onto structure response. The model is based on the principles of nonlinear system dynamics, i.e., consists of a system of nonlinear differential equations. In contrast to classical linearized models, this one comprises mass and loading as integral parts of the model. Application of the Kelvin and the Maxwell material models relates the novel formulation to the existing material formulations. All the analysis is performed on a proprietary computer program based on Wolfram Mathematica. This work can be considered as an extended proof of concept for the application of the nonlinear solid model in material response to dynamic loading.

How Do Electromagnetic Waves Originate\ulcorner (Electromagnetic Wave는 어떻게 발생하나\ulcorner)

  • 김영상;고재중;강상욱;이영주;강유진;서일환
    • Korean Journal of Crystallography
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    • v.14 no.1
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    • pp.25-31
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    • 2003
  • Accelerated electric charge is the source of electromagnetic waves. If electric charge is accelerated, the electric field set up by the electric charge is also accelerated. A changing electric field produces a changing magnetic field and the changing magnetic field produces an electric field and the process is self-perpetuating. The lines of B as well as E thus occurred form closed loops that move away from the source with speed c. These traveling electric and magnetic fields. which are strongly interdependent, constitute electromagnetic radiation. All the properties of electromagnetic waves can be deduced mathematically from Maxwell's equations.

Finite Element Analysis of Electromechanical Field of a Spindle Motor in a Computer Hard Disk Drive Considering Speed Control Using PWM and Mechanical Flexibility (PWM에 의한 속도 제어와 유연 구조를 고려한 컴퓨터 하드디스크 드라이브용 스핀들 모터의 기전 연성 유한 요소 해석)

  • Jang, Jeong-Hwan;Jang, Geon-Hui
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.9
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    • pp.499-508
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    • 2002
  • This paper presents a finite element analysis of the electromechanical field in the spindle motor of a computer hard disk drive considering the speed control and mechanical flexibility. The driving circuit equation is modified by considering the switching action of PWM inverter, and is coupled with the Maxwell equation to obtain the nonlinear time-stepping finite element equation for the analysis of magnetic field. Magnetic force and torque are calculated by the Maxwell stress tensor. Mechanical motion of a rotor is determined by a time-stopping finite element method considering the flexibility of shaft, rotor and bearing. Both magnetic and mechanical finite element equations are combined in the closed loop to control the speed using PWM. Simulation results are verified by the experiments, and they are in food agreement with the experimental results.