• Title/Summary/Keyword: velocity variations

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Dynamic interaction analysis between actively controlled Maglev and bridge (능동제어되는 자기부상열차와 교량의 동적상호작용해석)

  • Lee, Jun-Seok;Kwon, Soon-Duck;Yu, In-Ho;Kim, Moon-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2008.04a
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    • pp.555-560
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    • 2008
  • Dynamic interaction analysis between actively controlled Maglev and bridge is carried out. For this, dynamic governing equation for 2-dof Maglev vehicle and optimal feedback control scheme of DOFC are developed. And then the dynamic effect of the 1st natural frequency of bridge, vehicle/bridge mass ratio and damping coefficient of bridge to the both of air-gap variations of UTM-01 maglev vehicle and bridge center maximum displacement response are investigated. From the results of numerical simulation, it is found that the 1st natural frequency of bridge, vehicle/bridge mass ratio and damping coefficient of bridge does not affect greatly within design velocity of the vehicle.

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A study on safety evaluation by changing smoke ventilation mode in subway tunnels (지하철터널 환기변환모드에 따른 안전성 평가에 관한 연구)

  • Rie, Dong-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.4
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    • pp.389-400
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    • 2003
  • In order to recommend the mechanical smoke exhaust operation mode, Subway Environmental Simulation (SES) is used to predict the airflow of the inlet and outlet tunnel for the subway station. Fire Dynamic Simulation (FDS) is used the SES's velocity boundary conditions to clarity the smoke exhaust effectiveness by the variations with mechnical ventilation system. We compared each 6 types of smoke exhaust systems for the result of smoke density and temperature distributions for 1.5m height from the subway station base in order to clarify the safety evaluation for the heat and smoke exhaust on subway fire.

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Effects of atmospheric turbulence on the laser cross-beam velocimeter (레이저 크로스빔 속도계에 대한 대기교란 효과)

  • sung pyung-shik
    • Journal of the Korea Computer Industry Society
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    • v.6 no.2
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    • pp.259-264
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    • 2005
  • This paper have derived an expression(the fringe modle is used) for the photocurrelation-correlation function for a cross-beam laser velocimeter, taking into account the effects of atmospheric turbulence on the amplitude and phase of the incident beams. the result, as long as the atmospheric disturbances do not greatly damp out sinusoidal variations of the photocurrent-correlation function in the time it takes a particle to travel the fringe-separation distance, the disturbances do not hinder the determination of the velocity of the partides from the correlation funtion.(the scattering particles are assumed to have a well-defined V).

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A Study on Characteristics Analysis of Low Velocity Impact Response of CF/Epoxy Composite Plates (CF/Epoxy 복합적층판의 저속충격 특성평가에 관한 연구)

  • 임광희;박노식;김영남;김정호;김선규;심재기;양인영
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.85-88
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    • 2002
  • We have implemented a system of falling weight impact tester. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that of quasi-isotropic specimen over impact energy 7J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed of stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. Delamination area of impacted specimens was measured with ultrasonic C-scanner to find correlation between impact energy and delamination area. Delamination area and frequency responses was evaluated between impacted and unimpacted specimens. There is a strong correlation between frequency responses and impact-induced delamination. The presence and scale of damages have been investigated based on the variations of frequency responses.

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The Behavior of Unsteady Saline Wedge (염수쐐기의 비정상적 거동특성)

  • 이문옥
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.3 no.2
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    • pp.72-80
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    • 1991
  • This study presents the behavior of unsteady saline wedge in which it is examined velocity profile variations at the lower layer (inner wedge) and wedge tip responses to a tidal action in a rectangular open channel. Unsteady saline wedge has just tidal excursions corresponding to tidal amplitudes at the river mouth, although two wedge tips in flood and ebb tide remarkably have different shapes. Maximum velocities at the lower layer appear immediately from high water to low water level (or low to high water). Numerical computation results obtained by only just interfacial friction factor at the steady state show satisfactory agreements with experimental data. However, the numerical model on one-demensional two-layer flor still has some problems to date.

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Experiment of Turbulent Heat Transfer Performance Enhancement in Rod Bundle Subchannel by the Large Scale Vortex Flow (대형 2차 와류에 의한 봉다발 부수로에서의 난류 열전달 향상에 관한 실험적 연구)

  • Seo, Kwi-Hyun;Choi, Young-Don
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1592-1597
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    • 2004
  • Experimental studies were carried out to confirm the turbulent enhancement of the cooling system of nuclear reactor by large scale vortex generation in nuclear fuel rod bundle. The large scale vortex motions were generated by rearranging the inclination angles of mixing vanes to the coordinate directions. Experimental studies were carried out at Reynolds Number 60,000 with hydraulic condition. Normal variations of mean velocity and turbulent intensity in the rod bundle subchannel were measured by the 2-color LDV measurement system. The turbulence generated by split mixing vanes has small length scales so that they maintain only about 10DH after the spacer grid. On the other hand, the turbulences generated by the large scale vortex continue more and remain up $25D_{H}$ after the spacer grid.

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Tension Control in a Nonlinear Web Transfer System (비선형 웹 이송 시스템의 장력 제어)

  • 윤석찬
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.5
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    • pp.65-72
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    • 2000
  • This paper presents the study of the tension control in a web transfer system. In this study the sliding mode controller is applied to a time-varying nonlinear mathematical model. The model was derived to consider the effects of changing the roll radius in tension variation during winding and unwinding. The uncertainty in modeling may be due to unmodelled dynamics, on variations in system model. Designed sliding mode controller made the system error always staying in the suggested surface from the beginning. Through this, system is maintained to be robust against a disturbance and uncertainty. To verify the designed controller has a good performance, various inputs such as desired velocity, step input, and trapezoidal input are applied. When the sliding mode controller was used, the system(the tension control) performance was improved comparing to the PID controller. The robustness of the controller with respect to an estimation error was verified through simulations.

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ROBUST CONTROLLER DESIGN FOR IMPROVING VEHICLE ROLL CONTROL

  • Du, H.;Zhang, N
    • International Journal of Automotive Technology
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    • v.8 no.4
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    • pp.445-453
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    • 2007
  • This paper presents a robust controller design approach for improving vehicle dynamic roll motion performance and guaranteeing the closed-loop system stability in spite of vehicle parameter variations resulting from aging elements, loading patterns, and driving conditions, etc. The designed controller is linear parameter-varying (LPV) in terms of the time-varying parameters; its control objective is to minimise the $H_{\infty}$ performance from the steering input to the roll angle while satisfying the closed-loop pole placement constraint such that the optimal dynamic roll motion performance is achieved and robust stability is guaranteed. The sufficient conditions for designing such a controller are given as a finite number of linear matrix inequalities (LMIs). Numerical simulation using the three-degree-of-freedom (3-DOF) yaw-roll vehicle model is presented. It shows that the designed controller can effectively improve the vehicle dynamic roll angle response during J-turn or fishhook maneuver when the vehicle's forward velocity and the roll stiffness are varied significantly.

Numerical Simulation of Flow-Induced Birefringence: Comparison of Injection and Injection/Compression Molding

  • Lee, Ho-Sang;Isayev, A.I.
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.1
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    • pp.66-72
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    • 2007
  • A computer code was developed to simulate the filling stage of an injection/compression molding process using a finite element method. The constitutive equation was the compressible Leonov model and the PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Simulations of a disk under different processing conditions, including variations of the compression stroke and compression speed, were performed to determine their effects on the flow-induced birefringence. Simulated pressure traces were also compared to those obtained in conventional injection molding and with experimental data from the literature.

Robust Velocity Control for Inverter-Driven Hydraulic Elevators Using $DGKF/\mu$ Approach ($DGKF/\mu$ 기법을 이용한 인버터구동 유압 엘리베이터의 강인한 속도 제어)

  • Kang, Ki-Ho;Kim, Kyoung-Seo
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.2
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    • pp.217-227
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    • 2000
  • Although inverter-driven hydraulic elevators(HEL's) have advantages over traditional valve-controlled HEL's energy efficiency and performance they need robustness in performance and stability to accomodate nonlinearities big parametric variations and resonances in mechanical-hydraulic inner system. In this paper a robust controller based on DGKF/$\mu$ mixed approach is applied to a HEL system with carring capacity of 24 persons for Incheon International Airport. The results of a test tower(T/T) has shown good ro-bustness in performance and stability of the proposed controller thereby proving a feasibility of this robust controller-based approach for other HEL problems.

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