• Title/Summary/Keyword: inertia

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Control Algorithm for Wind Turbine Simulator with Variable Inertia Emulation (가변관성 모의 기능을 가진 풍력터빈 시뮬레이터의 제어 알고리즘)

  • 정병창;정세종;송승호
    • The Transactions of the Korean Institute of Power Electronics
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    • v.8 no.3
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    • pp.266-273
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    • 2003
  • A wind turbine simulator is developed for the emulation of variable input torque from the wind energy without actual rotor blades using motor-generator set. The torque command of dc motor is calculated from the characteristic equation of rotor blade during the change of wind speed. Especially the proposed control algorithm takes into account the fact that the moment of inertia of blade is much larger than that of driving motor. If you select the desired value of inertia, the stored/restored energy of the inertia during acceleration/deceleration can be compensated effectively resulting the only net torque is delivered to the generator. The simulator set-up has been designed and implemented using a do motor and drive. Feasibility of the proposed algorithm is verified by computer simulations and experiments.

Thermal Modeling of Comet-Like Objects from AKARI Observations

  • Bach, Yoonsoo P.;Ishiguro, Masateru;Usui, Fumihiko
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.49.3-50
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    • 2017
  • There have been recent studies which revealed a tendency that thermal inertia decreases with the size of asteroidal bodies, and suggestions that thermal inertias of cometary bodies should be much smaller than those asteroidal counterparts, regardless of comets' nuclear sizes, which hints a way to differentiate cometary candidates from asteroids using thermal inertia information. We thus selected two comet-like objects from AKARI satellite of JAXA, namely, 107P/ (4015) Wilson-Harrington and P/2006 HR30 (Siding Spring), and applied simple thermophysical model to test the idea. Both targets did not show any comet-like activity during the observations. From the model, we found Wilson-Harrington to have size of 3.7-4.4 km, geometric albedo 0.040-0.055 and thermal inertia of 100-250 J m-2 K-1 s-0.5, which coincide with previous works, and HR30 to have size of 24-27 km, geomoetric albedo of 0.035-0.045 with thermal inertia of 250-1000 J m-2 K-1 s-0.5. HR30 is found to have the rotation pole near the ecliptic plane (the latitude between -20 and +60 deg). Based on the results, we conjecture that comet-like objects are not clearly distinguishable from asteroidal counterpart using thermal inertia.

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Free vibration analysis of a Timoshenko beam carrying multiple spring-mass systems with the effects of shear deformation and rotary inertia

  • Wang, Jee-Ray;Liu, Tsung-Lung;Chen, Der-Wei
    • Structural Engineering and Mechanics
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    • v.26 no.1
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    • pp.1-14
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    • 2007
  • Because of complexity, the literature regarding the free vibration analysis of a Timoshenko beam carrying "multiple" spring-mass systems is rare, particular that regarding the "exact" solutions. As to the "exact" solutions by further considering the joint terms of shear deformation and rotary inertia in the differential equation of motion of a Timoshenko beam carrying multiple concentrated attachments, the information concerned is not found yet. This is the reason why this paper aims at studying the natural frequencies and mode shapes of a uniform Timoshenko beam carrying multiple intermediate spring-mass systems using an exact as well as a numerical assembly method. Since the shear deformation and rotary inertia terms are dependent on the slenderness ratio of the beam, the shear coefficient of the cross-section, the total number of attachments and the support conditions of the beam, the individual and/or combined effects of these factors on the result are investigated in details. Numerical results reveal that the effect of the shear deformation and rotary inertia joint terms on the lowest five natural frequencies of the combined vibrating system is somehow complicated.

Hard-landing Simulation by a Hierarchical Aircraft Landing Model and an Extended Inertia Relief Technique

  • Lee, Kyu Beom;Jeong, Seon Ho;Cho, Jin Yeon;Kim, Jeong Ho;Park, Chan Yik
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.3
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    • pp.394-406
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    • 2015
  • In this work, an efficient aircraft landing simulation strategy is proposed to develop an efficient and reliable hard-landing monitoring procedure. Landing stage is the most dangerous moment during operation cycle of aircraft and it may cause structural damage when hard-landing occurs. Therefore, the occurrence of hard-landing should be reported accurately to guarantee the structural integrity of aircraft. In order to accurately determine whether hard-landing occurs or not from given landing conditions, full nonlinear structural dynamic simulation can be performed, but this approach is highly time-consuming. Thus, a more efficient approach for aircraft landing simulation which uses a hierarchical aircraft landing model and an extended inertia relief technique is proposed. The proposed aircraft landing model is composed of a multi-body dynamics model equipped with landing gear and tire models to extract the impact force and inertia force at touch-down and a linear dynamic structural model with an extended inertia relief method to analyze the structural response subject to the prescribed rigid body motion and the forces extracted from the multi-body dynamics model. The numerical examples show the efficiency and practical advantages of the proposed landing model as an essential component of aircraft hard-landing monitoring procedure.

A Study on Proof of Equalities and Inequalities Using Moment of Inertia (관성능률을 이용한 등식 및 부등식의 증명에 대한 연구)

  • Han, In-Ki;Son, Jin-O;Lee, Kwang-Rok;Baek, Soo-Hean;Song, A-Rom;Chung, Ki-Young
    • Communications of Mathematical Education
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    • v.22 no.1
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    • pp.53-63
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    • 2008
  • In this paper we study a new proof method of equalities and inequalities using moment of inertia. We analyze proof method using moment of inertia, and describe how to prove equalities and inequalities using moment of inertia.

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Development of Simulator for High-Speed Elevator System (고속 엘리베이터 시스템용 시뮬레이터 개발)

  • Ryu, Hyung-Min;Kim, Sung-Jun;Sul, Seung-Ki;Kwon, Tae-Seok;Kim, Ki-Su;Shim, Young-Seok;Seok, Ki-Riong
    • Proceedings of the KIEE Conference
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    • 2001.04a
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    • pp.332-334
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    • 2001
  • This paper presents the simulator system of high-speed elevator system, which can be implemented as 3-mass system as well as equivalent 1-mass system. In order to implement the equivalent inertia of total elevator system, conventional simulator has generally utilized mechanical inertia (flywheel) with large radius, which makes the size and weight of total simulator system large. In addition, the mechanical inertia should be replaced each time in order to test the another elevator system. In this paper, the simulation method using electrical inertia is presented so that the volume and weight of simulator system are greatly reduced and the adjustment of value of the inertia can be achieved easily by software. Experimental results show the feasibility of this simulator system.

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Phase Portrait Analysis-Based Safety Control for Excavator Using Adaptive Sliding Mode Control Algorithm (적응형 슬라이딩 모드 제어를 이용한 위상 궤적 해석 기반 굴삭기의 안전제어 알고리즘 개발)

  • Oh, Kwang Seok;Seo, Ja Ho;Lee, Geun Ho
    • Journal of Drive and Control
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    • v.15 no.3
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    • pp.8-13
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    • 2018
  • This paper presents a phase portrait analysis-based safety control algorithm for excavators, using adaptive sliding mode control. Since working postures and material types cause the excavator's rotational inertia to vary, the rotational inertia was estimated, and this estimation was used to design an adaptive sliding mode controller for collision avoidance of the excavator. In order to estimate the rotational inertia, the recursive least-squares estimation with multiple forgetting was applied with the information of the swing velocity of the excavator. For realistic evaluation, an actual working scenario-based performance evaluation was conducted. Based on the estimated rotational inertia and an analysis of estimation errors, sliding mode control inputs were computed. The actual working scenario-based performance evaluation of the designed safety algorithm was conducted, and the results showed that the developed safety control algorithm can efficiently avoid a collision with an object in consideration of rotational inertia variations.

Autonomous Pole Placement Controller Design of Two-Inertia Motor System Based on Genetic Algorithms (유전자 알고리즘을 사용한 2관성 모터 시스템의 자동 극배치 제어기 설계)

  • Gloria Suh;Park, Jung-Il
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.40 no.5
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    • pp.317-325
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    • 2003
  • The vibration, which often occurred in a two inertia motor system, makes it difficult to achieve a quick response of speed and disturbance rejection. This paper provides an autonomous pole assignment technique for three kinds of speed controllers (I-P, I-PD, and State feedback) using GAs(Genetic Algorithms) for a two-inertia motor system. Firstly, the optimal parameters are chosen using GAs in view of reducing overshoot and settling time, then those are used in computing the gains of each controller. Some simulation results verify the effectiveness of the proposed design. The proposed controller is expected to be the autonomous design way for controlling a two-inertia motor system with flexible shaft.

Analysis of COMS In-Orbit Test for Moment of Inertia Measurement (천리안위성 관성모멘트의 궤도상 측정 시험 분석)

  • Park, Keun-Joo;Park, Young-Woong;Choi, Hong-Taek
    • Aerospace Engineering and Technology
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    • v.10 no.2
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    • pp.121-127
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    • 2011
  • In the attitude and orbit control subsystem design, the moment of inertia of the satellite is the major contributor to be considered. Satellites equipped with large solar arrays need to measure the moment of inertia accurately to avoid the interference of the thruster actuation period with its flexible mode. In this paper, the in-orbit tests of COMS to measure the moment of inertia are described. Then, the differences between the measured through in-orbit test and the predicted are compared. Finally, it is verified that the differences are below uncertainty bounds considered in the critical design of COMS attitude and orbit control subsystem.

A Study on the Oil Inertia Effect and Frequency Response Characteristics of a Servo Valve-Metering Cylinder System (서보밸브-미터링 실린더 시스템의 오일 관성효과와 주파수 응답 특성에 관한 연구)

  • Yun, Hongsik;Kim, SungDong
    • Journal of Drive and Control
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    • v.18 no.2
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    • pp.9-19
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    • 2021
  • The spool displacement signal of a directional control valve, including the servo valve, can be considered as the standard signal to measure dynamic characteristics. When the spool displacement signal is not available, the velocity signal of a metering cylinder piston can be used. In this study, the frequency response characteristics of the metering cylinder are investigated for the spool displacement input. The transfer functions of the servo valve-metering system are derived taking into consideration the oil inertia effect in the transmission lines. The theoretical results of the transfer functions are verified through computer simulations and experiments. The oil inertia effect in the transmission lines was found to have a very significant effect on the bandwidth frequency of the servo valve-metering cylinder system. In order to more precisely measure the dynamic characteristics of a servo valve, the metering cylinder should be set up to minimize the oil inertia effect by increasing the inner diameters of the transmission lines or shortening their lengths.