• 제목/요약/키워드: Dynamic parameter

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Dynamic instability analysis for S-FGM plates embedded in Pasternak elastic medium using the modified couple stress theory

  • Park, Weon-Tae;Han, Sung-Cheon;Jung, Woo-Young;Lee, Won-Hong
    • Steel and Composite Structures
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    • 제22권6호
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    • pp.1239-1259
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    • 2016
  • The modified couple stress-based third-order shear deformation theory is presented for sigmoid functionally graded materials (S-FGM) plates. The advantage of the modified couple stress theory is the involvement of only one material length scale parameter which causes to create symmetric couple stress tensor and to use it more easily. Analytical solution for dynamic instability analysis of S-FGM plates on elastic medium is investigated. The present models contain two-constituent material variation through the plate thickness. The equations of motion are derived from Hamilton's energy principle. The governing equations are then written in the form of Mathieu-Hill equations and then Bolotin's method is employed to determine the instability regions. The boundaries of the instability regions are represented in the dynamic load and excitation frequency plane. It is assumed that the elastic medium is modeled as Pasternak elastic medium. The effects of static and dynamic load, power law index, material length scale parameter, side-to-thickness ratio, and elastic medium parameter have been discussed. The width of the instability region for an S-FGM plate decreases with the decrease of material length scale parameter. The study is relevant to the dynamic simulation of micro structures embedded in elastic medium subjected to intense compression and tension.

UKF 기반한 동역학 시스템 파라미터의 추정 (Parameter Estimation of Dynamic System Based on UKF)

  • 승지훈;정길도
    • 한국산학기술학회논문지
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    • 제13권2호
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    • pp.772-778
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    • 2012
  • 본 논문은 비선형 시스템의 상태 추정에 널리 사용 되는 Unscented Kalman Filter(UKF)를 활용하여 동역학 시스템의 상태를 추정함과 동시에 파라미터를 추정하였다. 파라미터의 추정은 시스템 제어, 모델링, 성능분석 및 예측 등 다양한 분야에서 매우 중요하다. 공학에서 다루는 대부분의 시스템은 비선형성과 잡음이 존재하므로 파라미터 추정이 매우 어렵다. 이러한 경우에 대하여 본 논문에서는 비선형 필터로서 잡음에 강한 UKF를 이용하여 상태와 파라미터를 추정하였다. 본 논문에서 제안한 파라미터 추정은 기존의 상태방정식에 파라미터 항을 추가하여 확장된 비선형 방정식을 사용하였으며, 진자와 슬라이드로 구성된 2-자유도 동역학 시스템에 적용하였으며, 시스템 운동방정식의 측정 잡음으로 가우시안 잡음을 추가하여 컴퓨터 시뮬레이션을 실시하였다. 시뮬레이션 결과 제안한 방법이 LSM보다 좋은 성능을 보였다. 추정 오차는 3%이내이며, 0.1sec 이내의 수렴하는 것을 확인하였다. 결과적으로 UKF는 상태나 측정 데이터에 잡음이 존재하더라도 시스템의 상태 및 파라미터 추정이 가능하다.

Dynamic Heterogeneity in Spin Facilitated Model of Supercooled Liquid: Crossover from Fragile to Strong Liquid Behavior

  • Choi, Seo Woo;Kim, Soree;Jung, YounJoon
    • EDISON SW 활용 경진대회 논문집
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    • 제3회(2014년)
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    • pp.183-195
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    • 2014
  • Kinetically constrained models (KCM) have attracted interest as models that assign dynamic origins to the interesting dynamic properties of supercooled liquid. Signs of dynamic heterogeneity in the crossover model that linearly interpolates between the FA-like symmetric constraint and the East model constraint by asymmetric parameter b were investigated using Monte Carlo technique. When the asymmetry parameter was decreased sufficiently, smooth fragile-to-strong dynamic transition was observed in terms of the relaxation time, diffusion constant, Stokes-Einstein violation, and dynamic length scale. Competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism is behind such transition.

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통합모델과 최적 경로설계를 통한 산업용 로봇 동적 매개변수 규명 (Optimal Excitation Trajectories for the Dynamic Parameter Identification of Industrial Robots by Using Combined Model)

  • 박경조
    • 동력기계공학회지
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    • 제12권2호
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    • pp.55-61
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    • 2008
  • This paper discusses the advantages of using Fourier-based periodic excitation and of combining internal and external models in dynamic robot parameter identification. Internal models relate the joint torques or forces with the motion of the robot; external models relate the reaction forces and torques on the bedplate with the motion data. This combined model allows to combine joint torque/force and reaction torque/force measurements in one parameter estimation scheme. This combined model estimation will yield more accurate parameter estimates, and consequently better predictions of actuator torque, which is shown by means of a simulated experiment on a CRS A465 industrial robot.

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시변시스템을 위한 RBF 신경망 기반의 QFT 파라미터계획 제어기법과 alt일 제어시스템에의 적용 (RBF Network Based QFT Parameter-Scheduling Control Design for Linear Time-Varying Systems and Its Application to a Missile Control System)

  • 임기홍;최재원
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.199-199
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    • 2000
  • Most of linear time-varying(LTV) systems except special cases have no general solution for the dynamic equations. Thus, it is difficult to design time-varying controllers in analytic ways, and other control design approaches such as robust control have been applied to control design for uncertain LTI systems which are the approximation of LTV systems have been generally used instead. A robust control method such as quantitative feedback theory(QFT) has an advantage of guaranteeing the stability and the performance specification against plant parameter uncertainties in frozen time sense. However, if these methods are applied to the approximated linear time-invariant(LTI) plants which have large uncertainty, the designed control will be constructed in complicated forms and usually not suitable for fast dynamic performance. In this paper, as a method to enhance the fast dynamic performance, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks for LTV systems with bounded time-varying parameters.

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MODELING AND PARAMETER IDENTIFICATION FOR A PASSIVE HYDRAULIC MOUNT

  • Zhang, Y.X.;Zhang, J.W.;Shangguan, W.B.;Feng, Q.Sh.
    • International Journal of Automotive Technology
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    • 제8권2호
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    • pp.233-241
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    • 2007
  • A lumped parameter model is proposed for the analysis of dynamic behaviour of a Passive Hydraulic Engine Mount (PHEM), incorporating inertia track and throttle, which is characterized by effective and efficient vibration isolation behaviour in the range of both low and high frequencies. Most of the model parameters, including volume compliance of the throttle chamber, effective piston area, fluid inertia and resistance of inertia track and throttle are identified by an experimental approach. Numerical predictions are obtained through a finite element method for responses of dynamic stiffness of the rubber spring. The experiments are made for the purpose of PHEM validation. Comparison of numerical results with experimental observations has shown that the present PHEM achieves good performance for vibration isolation.

동적파라미터 변동을 고려한 윈치 및 부하 운동제어시스템설계에 관한 연구 (A study on winch and load motion control system design considering dynamic parameter variation)

  • 박환철;김영복
    • 수산해양기술연구
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    • 제53권3호
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    • pp.293-301
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    • 2017
  • In this study, a winch and load motion control system design method is introduced. Especially, the winch and load (moving cart) are connected with long wire rope which is extended to few kilometers long. Therefore, the rope length changes such that many dynamic parameter values are changed as well by winding and releasing the rope from the winch system. In this paper, the authors designed the control system by considering the real time parameter variation to occupy and keep good control performance continuously. The effectiveness of introduced method was evaluated by simulation results.

전자기 해석법에 의한 직선형 스위치드 릴럭턴스 전동기의 회로정수 도출 및 동특성 해석 (Analysis on Dynamic Characteristic and Circuit Parameter of Linear Switched Reluctance Motor by Electromagnetic Analytical Method)

  • 박지훈;고경진;최장영;장석명
    • 전기학회논문지
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    • 제59권2호
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    • pp.318-327
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    • 2010
  • This paper deals with analysis on dynamic characteristic and circuit parameter of linear switched reluctance motor by electromagnetic analytical method. Above all, using space harmonic method, which is electromagnetic method, the air-gap flux density is analyzed in the both align and unaign positions, and the inductance profile, force characteristic and resistance per phase are calculated by means of the process. The validity of the analyzed results are demonstrated by the finite element method(FEM) and manufacture of the prototype machine. Second, the dynamic simulation is analyzed by the use of circuit parameters derived from analytical method, and the operating system of the prototype machine is manufactured to demonstrated the validity of simulation analysis. As a result, it is considered that the characteristic equation suggested in this paper will contribute to the design, analysis and application of LSRM.

다이어프램형 밸브의 유량특성과 동적성능에 관한 연구 (A Study on Flow Rate Characteristic and Dynamic Performance on Diaphragm Solenoid Valve)

  • 정찬세;양순용
    • 드라이브 ㆍ 컨트롤
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    • 제10권3호
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    • pp.27-33
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    • 2013
  • Solenoid valve has used in various industrial field extensively. A solenoid valve has different size, shape and method of operation accordantly to industrial field. Many researchers study on kinds of solenoid valve such as flow rate, dynamic, magnetic field, valve shape and operating method. But the flow rate characteristic and dynamic response time performance on the diaphragm valve are not studied. This paper describes the flow rate characteristic and dynamic response time performance on the diaphragm valve. At first, the diaphragm valve is simulated in AMESim simulation tool. AMESim model found that an effect of valve performance depends on parameter. The parameter is the diaphragm orifice area. And the performance test bench confirms the effect in this parameter. Finally, it finds out the flow rate characteristic and dynamic response time performance on the diaphragm valve.

Application of computer algorithms for modelling and numerical solution of dynamic bending

  • Jianzhong, Qiu;Naichang, Dai;Akbar Shafiei, Alavijeh
    • Steel and Composite Structures
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    • 제46권1호
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    • pp.143-152
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    • 2023
  • In this paper, static and dynamic bending of nanocomposite micro beam armed with CNTs considering agglomeration effect is studied. The structural damping is considered by Kelvin-Voigt model. The agglomeration effects are assumed using Mori-Tanaka model. The micro beam is modeled by third order shear deformation theory (TSDT). The motion equations are derived by principle of Hamilton's and energy method assuming size effects on the basis of Eringen theory. Using differential quadrature method (DQM) and Newmark method, the static and dynamic deflections of the structure are obtained. The effects of agglomeration and CNTs volume percent, damping of structure, nonlocal parameter, length and thickness of micro-beam are presented on the static and dynamic deflections of the nanocomposite structure. Results show that with increasing CNTs volume percent, the static and dynamic deflections are decreased. In addition, enhancing the nonlocal parameter yields to higher static and dynamic deflections.