• Title, Summary, Keyword: space harmonic analysis

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An Experiment Study on the Chaos Phenomenon for a Rectangular Cantilever Beam (직사각형 외팔보의 혼돈현상에 대한 실험)

  • Kim, Myoung-Gu;Pak, Chul-Hui;Cho, Chong-Du;Piao, Chang-Hao
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.567-571
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    • 2005
  • The slender rectangular cantilever beam has vef interesting to study dynamic behaviors of the harmonic base excitation of a cantilever beam shows many nonlinear dynamics due to unstability , energy transfer and mode coupling. Nonlinear phenomenon shows superharmonic, subharmonic, super subharmonic and chaotic motions of the cantilever beam. Experimental observation and verification of these phenomenon carry much importance for the theoretical study as well as in it self. In the experimental cantilever beam, the chaotic motions of the beam appear as a pink noise signal in FFT analysis and as a torus structure in the oscilloscope analyzed to eventually give information of chaotic motions of the cantilever beam.

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2-D Periodic Unsteady Flow Analysis Using a Partially Implicit Harmonic Balance Method (부분 내재적 조화 균형법을 이용한 주기적인 2차원 비정상 유동 해석)

  • Im, Dong-Kyun;Park, Soo-Hyung;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.12
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    • pp.1153-1161
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    • 2010
  • An efficient solution method for harmonic balance techniques with Fourier transform is presented for periodic unsteady flow problems. The present partially-implicit harmonic balance treats the flux terms implicitly and the harmonic source term is solved explicitly. The convergence of the partially Implicit method is much faster than the explicit Runge-Kutta harmonic balance method. The method does not need to compute the additional flux Jacobian matrix from the implicit harmonic source term. Compared with fully implicit harmonic balance method, this partial approach turns out to have good convergence property. Oscillating flows over NACA0012 airfoil are considered to verify the method and to compare with results of explicit R-K(Runge-Kutta) and dual time stepping methods.

Simulation and Quasi-linear Theory of Magnetospheric Bernstein Mode Instability

  • Lee, Junggi;Yoon, Peter H.;Hwang, Junga;Choe, Gwang Son
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.2
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    • pp.70.1-70.1
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    • 2019
  • Multiple-harmonic electron cyclotron emissions, often known in the literature as the (n + 1∕2)fce emissions, are a common occurrence in the magnetosphere. These emissions are often interpreted in terms of the Bernstein mode instability driven by the electron loss cone velocity distribution function. Alternatively, they can be interpreted as quasi-thermal emission of electrostatic fluctuations in magnetized plasmas. The present paper carries out a one-dimensional relativistic electromagnetic particle-in-cell simulation and also employs a reduced quasi-linear kinetic theoretical analysis in order to compare against the simulation. It is found that the Bernstein mode instability is indeed excited by the loss cone distribution of electrons, but the saturation level of the electrostatic mode is quite low, and that the effects of instability on the electrons is rather minimal. This supports the interpretation of multiple-harmonic emission in the context of the spontaneous emission and reabsorption in quasi-thermal magnetized plasma in the magnetosphere.

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Maximum Thrust Design of Permanent Magnet Linear Synchronous Motor Using Genetic Algorithm and Surface Harmonic Method (유전알고리즘과 공간고조파법을 이용한 PMLSM의 출력 최대화 설계)

  • Lee, Dong-Yeup;Yoon, Kang-Jun;Kim, Gyu-Tak
    • Proceedings of the KIEE Conference
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    • pp.66-68
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    • 2003
  • This paper is deal with the method of design for the optimum model using genetic algorithms in slotted Permanent Magnet Linear Synchrous Motor (PMLSM). The objective functions are maximum thrust and minimum detent force. Characteristic analysis method is used 2D space harmonic analysis method. Design parameters are PM width, PM height and slot width.

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Cogging Torque Reduction Design for CVVT Using Response Surface Methodology (RSM을 이용한 CVVT용 전동기 코깅토크 저감 설계)

  • Kim, Jae-Yui;Kim, Dong-min;Park, Soo-Hwan;Hon, Jung-Pyo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.12
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    • pp.2183-2188
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    • 2016
  • This paper deals with the design process for an outer-rotor-type surface-mounted permanent magnet synchronous motor (SPMSM) used in continuous variable valve timing (CVVT) systems in automobiles with internal combustion engines. When the same size, outer-rotor-type SPMSMs generate larger torque and more stable than inner-rotor-type SPMSMs. For the initial design, space harmonic analysis (SHA) is used. In order to minimize the cogging torque, an optimization was conducted using Response Surface Methodology (RSM). At the end of the paper, Finite Element Analysis (FEA) is performed to verify the performance of the optimum model.

Model Predictive Control for Shunt Active Power Filter in Synchronous Reference Frame

  • Al-Othman, A.K.;AlSharidah, M.E.;Ahmed, Nabil A.;Alajmi, Bader. N.
    • Journal of Electrical Engineering and Technology
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    • v.11 no.2
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    • pp.405-415
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    • 2016
  • This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.

Performance Analysis and Comparison of Post-Fault PWM Rectifiers Using Various Space Vector Modulation Methods

  • Zhu, Chong;Zeng, Zhiyong;Zhao, Rongxiang
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2258-2271
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    • 2016
  • In this paper, some crucial performance characteristics related to the operational reliability of the post-fault Pulse Width Modulated (PWM) rectifiers, such as line current harmonic distortion, Common Mode Voltage (CMV), and current stress on the capacitors, are fully investigated. The aforementioned performance characteristics of post-fault rectifiers are highly dependent on the utilized space vector modulation (SVM) schemes, which are also examined. Detailed analyses of the three most commonly used SVM schemes for post-fault PWM rectifiers are provided, revealing the major differences in terms of the zero vector synthesis approaches. To compare the performances of the three SVM schemes, the operating principles of a post-fault rectifier are presented with various SVM schemes. Using analytical and numerical methods in the time domain, the performances of the line current distortion, common mode voltage and capacitor current are evaluated and compared for each SVM scheme. The proposed analysis demonstrates that the zero vector synthesis approaches of the considered methods have significant impacts on the performance characteristics of rectifiers. In addition, the advantages and disadvantages of the proposed SVM schemes are discussed. The experimental results verify the effectiveness and validity of the proposed analysis.

Harmonic Current Reference Generation of Single-Phase Active Filter for the Converter-Fed Locomotives (고속전철용 단상능동필터의 기준고조파전류 발생 방법)

  • Sung, Gi-Seok;Song, Joong-Ho;Choi, Ik;Choi, Ju-Yeop;Kim, Gwang-Bae;Kim, Kwon-Ho;Lim, Myo-Taek
    • Proceedings of the KIPE Conference
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    • pp.338-341
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    • 1999
  • PWM controlled line-side converters of modern ac traction locomotives inject harmonic currents into the feeding overhead line. This causes problem of electromagnetic interference. Passive and Active filters are usually provided for a reduction of the line harmonics. Active filters are more reasonable than passive filters in terms of weight and space of the filters. Successful control of active filters requires an accurate harmonic current reference. A technique to generate the harmonic current reference is proposed in this paper. The analysis is performed in frequency domain and its effectiveness is verified by simulation.

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Vibratory Loads Reduction of a Rotor in Slow Descent using Higher Harmonic Control Technology (고조파제어(HHC) 기법을 이용한 저속 하강 비행중인 로터의 진동하중 억제에 관한 연구)

  • You, Younghyun;Jung, Sung Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.6
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    • pp.440-447
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    • 2013
  • In this paper, a higher harmonic control (HHC) methodology is applied to find the optimum input scenario for the vibratory hub loads reduction. A comprehensive aeroelastic analysis code, CAMRAD II, is used to model the HART (Higher-harmonic-control Aeroacoustic Rotor Test) II rotor, and parametric study is conducted for the best HHC inputs leading to a minimum vibration (MV) condition. The resulting outcomes are compared with the earlier HART II test results. It is indicated that the control input adopted in the MV condition showed less satisfactory results. The new MV condition obtained in the present investigation can achieve 45% lower vibration level than the baseline uncontrolled condition. The optimum HHC input results lead to 3/rev harmonic input having $0.8^{\circ}$ amplitude and $350^{\circ}$ phase angle. About 5% reduction in the required power is possible but accompanies with the increase of vibration level.

Optomechanical Design and Vibration Analysis for Linear Astigmatism-Free Three Mirror System (LAF-TMS)

  • Park, Woojin;Lim, Jae Hyuk;Lee, Sunwoo;Hammar, Arvid;Kim, Sanghyuk;Kim, Yunjong;Jeong, Byeongjoon;Kim, Geon Hee;Chang, Seunghyuk;Pak, Soojong
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.2
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    • pp.47.1-47.1
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    • 2019
  • We report the design and vibration analysis for the optomechanical structures of Linear Astigmatism Free - Three Mirror System (LAF-TMS). LAF-TMS is the linear astigmatism free off-axis wide-field telescope with D = 150 mm, F/3.3, and FOV = 5.51° × 4.13°. The whole structure consists of four optomechanical modules. It can accurately mount mirrors and also can survive from vibration environments. The Mass Acceleration Curve (MAC) is adapted to the quasi-static analysis. Modal, harmonic, and random vibration analysis have been performed under the qualification level of the launch system. We evaluate the final results in terms of von Mises stress and Margin of Safety (MoS).

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