• 제목/요약/키워드: Non-linear Vibration

검색결과 403건 처리시간 0.022초

Reduced Density Matrix Theory for Vibrational Absorption Line Shape in Energy Transfer Systems: Non-Condon Effects in Water

  • Yang, Mi-No
    • Bulletin of the Korean Chemical Society
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    • 제32권2호
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    • pp.439-443
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    • 2011
  • Using the projection operator technique, a reduced density matrix theory for linear absorption spectrum of energy transfer systems is developed for the theoretical absorption line shape of the systems with non-Condon transitions. As an application, we considered a model system of OH vibrations of water. In the present model calculation, the OH vibration modes are coupled to each other via intra-molecular coupling mechanism while their intermolecular couplings are turned off. The time-correlation functions appearing in the formulation are calculated from a mixed quantum/classical mechanics method. The present theory is successful in reproducing the exact absorption line shape. Also the present theory was improved from an existing approximate theory, time-averaged approximation approach.

선형 및 비선형 부하 혼합 운전시 유도전동기의 동작 분석 (Operation Analysis of Induction Motor under the Combination of Linear & Non-linear Loads)

  • 김종겸;박영진;이동주;김준호;이종한;정종호;이은웅
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.65-67
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    • 2006
  • This paper presents a scheme on the characteristics of induction motor under the combination of linear & non-linear loads at the three phase 4-wire power distribution system. Under the combination operation of single & three phase load, voltage unbalance will be generated and current unbalance will be more severe by the dropped voltage quality. All power electronic converters used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the feeder grid of three phase 4-wire. Harmonic current may cause torque to decrease. Motors may also overheat or become noisy and torque oscillation in the rotor can lead to mechanical resonance and vibration.

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Experimental study of controllable MR-TLCD applied to the mitigation of structure vibration

  • Cheng, Chih-Wen;Lee, Hsien Hua;Luo, Yuan-Tzuo
    • Smart Structures and Systems
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    • 제15권6호
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    • pp.1481-1501
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    • 2015
  • MR-TLCD (Magneto-Rheological Tuned Liquid Column Damper) is a new developed vibration control device, which combines the traditional passive control property with active controllability advantage. Based on traditional TLCD governing equation, this study further considers MR-fluid viscosity in the equation and by transforming the non-linear damping term into an equivalent linear damping, a solution can be obtained. In order to find a countable set of parameters for the design of the MR-TLCD system and also to realize its applicability to structures, a series of experimental test were designed and carried out. The testing programs include the basic material properties of the MR-fluid, the damping ratio of a MR-TLCD and the dynamic responses for a frame structure equipped with the MR-TLCD system subjected to strong ground excitations. In both the analytical and experimental results of this study, it is found that the accurately tuned MR-TLCD system could effectively reduce the dynamic response of a structural system.

기체의 평균 움직임 추정에 기반한 무인항공기 영상 안정화 알고리즘 (UAV(Unmanned Aerial Vehicle) image stabilization algorithm based on estimating averaged vehicle motion)

  • 이홍석;고윤호;김병수
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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    • pp.216-218
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    • 2009
  • This paper proposes an image processing algorithm to stabilize shaken scenes of UAV(Unmanned Aerial Vehicle) caused by vehicle self-vibration and aerodynamic disturbance. The proposed method stabilizes images by compensating estimated shake motion which is evaluated from global motion. The global motion between two continuous images modeled by 6 parameter warping model is estimated by non-linear square method based on Gauss-Newton algorithm with excluding outlier region. The shake motion is evaluated by subtracting the global motion from aerial vehicle motion obtained by averaging global motion. Experimental results show that the proposed method stabilize shaken scenes effectively.

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불규칙 교란을 받는 비행체에 장착된 비선형 시스템의 난진동 해석 (Analysis on random vibration of a non-linear system in flying vehicle due to stochastic disturbances)

  • 구제선
    • 대한기계학회논문집
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    • 제14권6호
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    • pp.1426-1435
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    • 1990
  • 본 연구에서는 확률론적 등가선형화 기법을 사용하여 비선형 랜덤 시스템을 선형화하였다.또 이 선형화된 시스템을 최근에 새로이 제안된 방법을 적용하여 비 백색잡음형태의 랜덤 가진을 받을 때 그 거동을 구하였다.

축의 굽힘효과를 고려한 회전체에 장착된 자동평형장치의 동적해석 (Dynamic Analysis of an Automatic Dynamic Balancer in a Rotor with the Bending Flexibility)

  • 방인창;정진태
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.629-634
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    • 2000
  • Dynamic behavior of an automatic dynamic balancer is analyzed by a theoretical approach. Using Lagrange's equation, we derive the non-linear equations of motion for an automatic dynamic balancer equipped in a rotor with the bending flexibility with respect to the rectangular coordinate. Considering the rotor bending flexibility we analyze out-of-plane vibrations as well as in-plane vibrations of the automatic dynamic balaner. The time responses are computed from the non-linear equations by using a time integration method. We also investigate the effect of rotor flexibility on the behavior of the automatic dynamic balancer

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방위센서를 이용한 배열 형상 추정기법 (Array Shape Estimation Method Using Heading Sensors)

  • 조요한;서희선;조치영
    • 소음진동
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    • 제10권5호
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    • pp.886-891
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    • 2000
  • In this paper, an iterative array shape estimation technique is presented, which is based on the use of the least squares polynomial fitting to the data from heading sensors. The estimated polynomial shape model is then used for calculating the hydrophone positions on the assumption that the arc distances between sensors are constant. In order to verify the applicability of the proposed algorithm, numerical simulations are performed using two types of non-linear array shapes. In addition the noise effects of heading sensors on the array shape estimation results and the performance of beamformer are also investigated.

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면진장치 장착 스카이 브릿지의 사용성 평가 (Serviceability Evaluation of Sky Bridge With Isolation Device)

  • 김기철;김현수;김수근
    • 한국공간구조학회논문집
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    • 제17권2호
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    • pp.71-77
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    • 2017
  • In this study, the boundary non-linear analysis of the sky bridge subjected to walking load and running load is performed. The sky bridge is installed in the mid-story between two buildings and the walking load and running load induced by pedestrians are measured by load cell. LRB is modeled as a non-linear hysteresis model to accurately represent the behavior of LRB. For the serviceability evaluation of sky bridge, the acceleration responses of sky bridge are analyzed based on ISO 2631-2 and the velocity response are analyzed based on standards Bachmann &Amann. In serviceability evaluation of this sky bridge, the pedestrian can not perceive the vibration except for resonance running loads consequently. Therefore, it is concluded that this sky bridge haven't problem in the serviceability.

Experimental investigation of the large amplitude vibrations of a thin-walled column under self-weight

  • Goncalves, Paulo B.;Jurjo, Daniel Leonardo B.R.;Magluta, Carlos;Roitman, Ney
    • Structural Engineering and Mechanics
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    • 제46권6호
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    • pp.869-886
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    • 2013
  • This work presents an experimental methodology specially developed for the nonlinear large-amplitude free vibration analysis of a clamped-free thin-walled metal column under self-weight. The main contribution of this paper is related to the developed experimental methodology which is based on a remote sensing technique using a computer vision system that integrates, on-line, the digital image acquisition and its treatment through special image processing routines. The main importance of this methodology is that it performs large deflections measurements without making contact with the structure and thus, not introducing undesirable changes in its behavior, for instance, appreciable changes in mass and stiffness properties. This structure presents, in most cases, highly non-linear responses, which cannot be reproduced by conventional finite-element softwares due, mainly, to the simultaneous influence of geometric and inertial non-linearities. To capture the non-linearities associated with large amplitude vibration and be able to describe the buckling process, the structure is discretized as a sequence of jointed coupled elastic pendulums. The obtained numerical results are favorably compared with the experimental ones, in the pre- and post-buckling regimes.

Free vibration analysis of functionally graded plates with temperature-dependent properties using various four variable refined plate theories

  • Attia, Amina;Tounsi, Abdelouahed;Bedia, E.A. Adda;Mahmoud, S.R.
    • Steel and Composite Structures
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    • 제18권1호
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    • pp.187-212
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    • 2015
  • In this paper, various four variable refined plate theories are presented to analyze vibration of temperature-dependent functionally graded (FG) plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations for the present model is reduced, significantly facilitating engineering analysis. These theories account for parabolic, sinusoidal, hyperbolic, and exponential distributions of the transverse shear strains and satisfy the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Uniform, linear, nonlinear and sinusoidal thermal conditions are imposed at the upper and lower surface for simply supported FG plates. Equations of motion are derived from Hamilton's principle. Analytical solutions for the free vibration analysis are obtained based on Fourier series that satisfy the boundary conditions (Navier's method). Non-dimensional results are compared for temperature-dependent and temperature-independent FG plates and validated with known results in the literature. Numerical investigation is conducted to show the effect of material composition, plate geometry, and temperature fields on the vibration characteristics. It can be concluded that the present theories are not only accurate but also simple in predicting the free vibration responses of temperature-dependent FG plates.