• Title, Summary, Keyword: mode acceleration method

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Extension of indirect displacement estimation method using acceleration and strain to various types of beam structures

  • Cho, Soojin;Sim, Sung-Han;Park, Jong-Woong;Lee, Junhwa
    • Smart Structures and Systems
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    • v.14 no.4
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    • pp.699-718
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    • 2014
  • The indirect displacement estimation using acceleration and strain (IDEAS) method is extended to various types of beam structures beyond the previous validation on the prismatic or near-prismatic beams. By fusing different types of responses, the IDEAS method is able to estimate displacements containing pseudo-static components with high frequency noise to be significantly reduced. However, the concerns to the IDEAS method come from possible disagreement of the assumed sinusoidal mode shapes to the actual mode shapes, which allows the IDEAS method to be valid only for simply-supported prismatic beams and limits its applicability to real world problems. In this paper, the extension of the IDEAS method to the general types of beams is investigated by the mathematical formulation of the modal mapping matrix only for the monitored substructure, so-called monitoring span. The formulation particularly considers continuous and wide beams to extend the IDEAS method to general beam structures that reflect many real bridges. Numerical simulations using four types of beams with various irregularities are presented to show the effectiveness and accuracy of the IDEAS method in estimating displacements.

A Comparative Study on the Measurement of Smoke from Diesel Vehicle on Chassis-dynamometer using Reflection Photo and Light Extinction Method (차대 동력계에서의 디젤 차량의 매연 측정을 위한 여지 반사식 및 광투과식 측정법의 비교 연구)

  • Kim, Ju-Chul;Lee, Choong-Hoon
    • Journal of the Korean Society of Safety
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    • v.22 no.6
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    • pp.13-19
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    • 2007
  • Diesel car's smoke measurement equipment and method were investigated based on the exhaust gas regulations. Reflection photo method and light extinction method for measuring smoke were compared under conditions of both no load mode and Lug-down 3 mode. Free acceleration mode at no load condition was used for regular inspection of diesel car, and Lug-down 3 mode was used for fine inspection of the diesel car. A correlation between no load mode and Lug-down 3 mode was investigated in this research. The smoke measured with reflection photo method was 1.5${\sim}$2 times higher than that of light extinction method The correlation coefficient between reflection photo method and light extinction method for measuring smoke was 0.83, which shows comparatively high correlation between the two methods for measuring smoke in diesel engines.

Dynamic Response of a 2.75MW Wind Turbine Applying Torque Control Method Based on Torque-Mode (토크모드 기반의 토크 제어 방법을 적용한 2.75MW 풍력터빈의 동적 응답)

  • Lim, Chae-Wook
    • The KSFM Journal of Fluid Machinery
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    • v.16 no.6
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    • pp.5-11
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    • 2013
  • Torque control methods of wind turbine are mainly classified into two methods: torque-mode and speed-mode methods. The traditional torque-mode method, in which generator torque proportional to square of generator speed is determined, has been chosen in many wind turbines but its response is slower as they are larger in multi-MW size. Torque control methods based on both speed-mode and torque-mode can be used to make response of wind turbine faster. In this paper, two torque control methods based on the traditional torque-mode method are applied to a 2.75 MW wind turbine. It is shown through some simulation results for real turbulence wind speeds that torque control method based on torque-mode has the merit of reducing fluctuations of generated power than PI controller based on speed-mode.

Study on the Taxing Mode Control of MR Damper Landing Gear (MR 댐퍼 착륙장치의 택싱모드 제어기법에 대한 연구)

  • Lee, Hyosang;Hwang, Jaihyuk
    • Journal of Aerospace System Engineering
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    • v.13 no.6
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    • pp.43-51
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    • 2019
  • The aircraft vertical acceleration from the excitation of the road surface in the taxing mode is a main factor with a negative effect on the boarding quality of pilots and passengers. In this paper, we propose an appropriate control method to improve the boarding quality of the MR damper landing gear. The proposed control method is Skyhook Control Type 2, which feeds the aircraft vertical acceleration back in addition to the aircraft vertical velocity. Since Skyhook Control Type 2 factors the velocity and acceleration of the upper mass, it can be expected to exceed the control performance of the existing Skyhook Control that factors only the upper mass velocity. For the simulation, the bumper type road surface was selected as a ground surface, and the landing gear model constructed with RecurDyn and the controller designed with Simulink were co-simulated. The control effect of Skyhook Control Type 2 was verified by comparing and analyzing the RMS and maximum value of the upper mass acceleration according to the taxing speed and control method.

SLIP CONTROLLER DESIGN FOR TRACTION CONTROL SYSTEM

  • Jung, H.;Kwak, B.;Park, Y.
    • International Journal of Automotive Technology
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    • v.1 no.1
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    • pp.48-55
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    • 2000
  • Two major roles of the traction control system (TCS) are to guarantee the acceleration performance and directional stability even in extreme road conditions, under which average drivers may not control the car properly. Commercial TCSs use experiential methods such as lookup table and gain-scheduling to achieve proper performance under various road and vehicle conditions. This paper proposes a new slip controller which uses the brake and the throttle actuator simultaneously. To avoid measurement problems and to get a simple structure, the brake controller and the throttle controller are designed using Lyapunov redesign method and multiple sliding mode control respectively. Through the hybrid use of brake and throttle controllers, the vehicle is insensitive to the variation of the vehicle mass, brake gain and road condition and can achieve the required acceleration performance. The proposed method is validated with simulations based on 15 DOF passenger car model.

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Analysis of three dimensional equivalent static wind loads of symmetric high-rise buildings based on wind tunnel tests

  • Liang, Shuguo;Zou, Lianghao;Wang, Dahai;Huang, Guoqing
    • Wind and Structures
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    • v.19 no.5
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    • pp.565-583
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    • 2014
  • Using synchronous surface pressures from the wind tunnel test, the three dimensional wind load models of high-rise buildings are established. Furthermore, the internal force responses of symmetric high-rise buildings in along-wind, across-wind and torsional directions are evaluated based on mode acceleration method, which expresses the restoring force as the summation of quasi-static force and inertia force components. Accordingly the calculation methods of equivalent static wind loads, in which the contributions of the higher modes can be considered, of symmetric high-rise buildings in along-wind, across-wind and torsional directions are deduced based on internal forces equivalence. Finally the equivalent static wind loads of an actual symmetric high-rise building are obtained by this method, and compared with the along-wind equivalent static wind loads obtained by China National Standard.

Dynamic Characteristic Analysis of Trapezoidal Cantilever Plates Undergoing Translational Acceleration (가속을 받는 사다리꼴 외팔 평판의 동특성 해석)

  • 임홍석;유홍희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.268-273
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    • 2002
  • A modeling method for the dynamic characteristic analysis of a translationally accelerated trapezoidal cantilever plate is presented in this paper. The equations of motion for the plate are derived and transformed into a dimensionless form. The effects of the inclination angles and the acceleration on the vibration characteristics of the plate are investigated. Incidentally, natural frequency loci veering and associated mode shape variations are observed and discussed

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Dynamic Characteristic Analysis of Trapezoidal Cantilever Plates Undergoing Translational Acceleration (가속을 받는 사다리꼴 외팔 평판의 동특성 해석)

  • 임홍석;유홍희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.10
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    • pp.785-791
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    • 2002
  • A modeling method for the dynamic characteristic analysis of a translationally accelerated trapezoidal cantilever plate is presented in this paper. The equations of motion for the plate are derived and transformed into a dimensionless form. The effects of the inclination angles and the acceleration on the vibration characteristics of the plate are investigated. Incidentally, natural frequency loci veering and associated mode shape variations are observed and discussed.

Integration of Measured Acceleration to Determine the Vibration Characteristics of Bridges (교량 진동특성 분석을 위한 실측 가속도의 적분)

  • ;;Lee, Sun-Goo;Lee, Mun-Taek
    • Computational Structural Engineering
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    • v.9 no.4
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    • pp.107-115
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    • 1996
  • Displacement response is one of the important parameter to determine vibration characteristics of bridge structure. Reliable estimate of displacement response is obtained economically from integration of measured acceleration data in frequency domain. Proper sampling rate of frequency in discretization process of measured acceleration is proposed. Comparison of integrated and directly measured displacement response from laboratory experiment for a cantilever beam shows good agreement each other. Mode shape obtained from estimated displacement response also closely match with analytical result, thus the developed method is proved to be effective in practical use.

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Estimation of Structural Displacements for Cantilever Beam Using Mode Shapes and Accelerometers Under Free Vibration (모드 형상과 가속도계를 이용한 자유 진동하는 외팔보의 변위 추정)

  • Kim, Kyung Jong;Lee, Yong Hwan;Lee, Kyu Beom;Lee, Cheol Soon;Cho, Jin Yeon;Kim, Jeong Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.5
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    • pp.376-385
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    • 2017
  • In this paper, a method for the estimation of structural displacements using structure's mode shapes and accelerations is suggested to reduce the disadvantages of acceleration time integration method. Acceleration time integration method requires accurate information on initial conditions, and errors caused by noise can be accumulated during time integration. To avoid these problems, the method for the estimation of structural displacements based on mode superposition method is developed and two vibration experiments for cantilever beam are conducted to verify this method. Static displacements and dynamic displacements of beam structure are estimated using measured accelerations from experiments and mode shapes of cantilever beam, and they are compared with measured displacements using laser displacement sensor. From these results, the validity and usefulness of this method are verified.