• Title/Summary/Keyword: ultimate dynamics

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Ultimate response of bionics shells

  • Tesar, Alexander;Minar, Michal
    • Structural Engineering and Mechanics
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    • v.14 no.2
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    • pp.135-150
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    • 2002
  • Numerical analysis of ultimate behaviour of thin bionics shells is treated in present paper. Interactive conditions in resonance and stability ultimate response are considered. Numerical treatment of nonlinear problems appearing is made using the updated Lagrangian formulation of motion. Each step of the iteration approaches the solution of linear problem and the feasibility of parallel processing FETM-technique with adaptive mesh refinement and substructuring for the analysis of ultimate action of thin bionics shells is established. Some numerical results are submitted in order to demonstrate the efficiency of the procedures suggested.

A robust controller design for robot manipulators with actuator dynamics (구동기의 동특성을 고려한 로봇매니퓰레이터의 강인제어기 설계)

  • 박광석;황동환
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.139-142
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    • 1997
  • In this paper, a robust controller is proposed to achieve an accurate tracking for an uncertain nonlinear plant with actuator dynamics. The extent of parameter uncertainty can be quantified by using linear parameterization technique. A switching controller is proposed to guarantee the global asymptotic stability of the plant. In order to eliminate the chattering caused by the switching controller, a smoothing controller is designed using the boundary layer technique around the sliding surface and guarantees the uniform ultimate boundedness of the tracking error.

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THE ROBUST CONTROLLER DESIGN FOR UNCERTAIN MULTIVARIABLE SYSTEM USING SWITCHING DYNAMICS

  • Park, Gwi-Tae;Kuo, Chun-Ping;Kim, Dong-Sik;Lim, Sung-Jun
    • 제어로봇시스템학회:학술대회논문집
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    • 1989.10a
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    • pp.924-930
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    • 1989
  • This paper presents the design of simple robust controller for a class of uncertain multivariable systems. We introduce switching dynamics instead of switching logics unlike variable structure control scheme. Also, we can construct the continuous control law from this switching dynamics and consequently remove the chattering motion. The dynamic equations of the range-space of a switching surface matrix C and uniform ultimate boundedness in the presence of parameter uncertainties are described mathematically.

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Studying the influences of mono-vacancy defect and strain rate on the unusual tensile behavior of phosphorene NTs

  • Hooman Esfandyari;AliReza Setoodeh;Hamed Farahmand;Hamed Badjian;Greg Wheatley
    • Advances in nano research
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    • v.15 no.1
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    • pp.59-65
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    • 2023
  • In this present article, the mechanical behavior of single-walled black phosphorene nanotubes (SW-αPNTs) is simulated using molecular dynamics (MD). The proposed model is subjected to the axial loading and the effects of morphological parameters, such as the mono-vacancy defect and strain rate on the tensile behavior of the zigzag and armchair SW-αPNTs are studied as a pioneering work. In order to assess the accuracy of the MD simulations, the stress-strain response of the current MD model is successfully verified with the efficient quantum mechanical approach of the density functional theory (DFT). Along with reproducing the DFT results, the accurate MD simulations successfully anticipate a significant variation in the stress-strain curve of the zigzag SW-αPNTs, namely the knick point. Predicting such mechanical behavior of SW-αPNTs may be an important design factor for lithium-ion batteries, supercapacitors, and energy storage devices. The simulations show that the ultimate stress is increased by increasing the diameter of the pristine SW-αPNTs. The trend is identical for the ultimate strain and stress-strain slope as the diameter of the pristine zigzag SW-αPNTs enlarges. The obtained results denote that by increasing the strain rate, the ultimate stress/ultimate strain are respectively increased/declined. The stress-strain slope keeps increasing as the strain rate grows. It is worth noting that the existence of mono-atomic vacancy defects in the (12,0) zigzag and (0,10) armchair SW-αPNT structures leads to a drop in the tensile strength by amounts of 11.1% and 12.5%, respectively. Also, the ultimate strain is considerably altered by mono-atomic vacancy defects.

Fuzzy Nonlinear Adaptive Control of Overhead Cranes for Anti-Sway Trajectory Tracking and High-Speed Hoisting Motion (고속 권상운동과 흔들림억제 궤적추종을 위한 천정주행 크레인의 퍼지 비선형 적응제어)

  • Park, Mun-Soo;Chwa, Dong-Kyoung;Hong, Suk-Kyo
    • Journal of the Korean Institute of Intelligent Systems
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    • v.17 no.5
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    • pp.582-590
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    • 2007
  • Nonlinear adaptive control of overhead cranes is investigated for anti-sway trajectory tracking with high-speed hoisting motion. The sway dynamics of two dimensional underactuated overhead cranes is heavily coupled with the trolley acceleration, hoisting rope length, and the hoisting velocity which is an obstacle in the design of decoupling control based anti-sway trajectory tracking control law To cope with this obstacle. we propose a fuzzy nonlinear adaptive anti-sway trajectory tracking control law guaranteeing the uniform ultimate boundedness of the sway dynamics even in the presence of uncertainties in such a way that it cancels the effect of the trolley acceleration and hoisting velocity on the sway dynamics. In particular. system uncertainties, including system parameter uncertainty unmodelled dynamics, and external disturbances, are compensated in an adaptive manner by utilizing fuzzy uncertainty observers. Accordingly, the ultimate bound of the tracking errors and the sway angle decrease to zero when the fuzzy approximation errors decrease to zero. Finally, numerical simulations are performed to confirm the effectiveness of the proposed scheme.

Public Policy and The Imbalance of The Systems: A System Dynamics Approach for The Shock of Lowered Retirement Age of Teachers on Education System

  • Yi, Mi-Sook;Choi, Nam-Hee;Kim, Doa-Hoon
    • Korean System Dynamics Review
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    • v.5 no.2
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    • pp.149-174
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    • 2004
  • Since the economic crisis in 1997, the Korean government has implemented a number of reforms in order to eliminate inefficiencies in both private and public sectors. One of the reforms made in the public sector was to lower the retirement age of teachers from the original age of 65 to that age 62. The ultimate aim of this compulsory policy was to improve the quality level of education by hiring many young teachers instead of senior teachers. It was made based on the calculation that by lowering the retirement age by three years, the government can hire three young teachers with the saved wages. However, this policy has brought an unexpected result; the imbalance between the supply and demand for teachers has become a much more serious problem in Korea's elementary education system The purpose of this study is largely twofold; First of all, it aims to identify the scope of imbalances occurred in the supply-demand system of elementary school teachers in a region of the nation, and also to find out why such imbalance occurred. Secondly, the purpose of this study is to experiment with feasible policy alternatives and their effects on the system and to suggest some resolutions on the imbalance.

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Image-based Robust Control of Robot Manipulators with Image Jacobian and Dynamics Uncertainties (영상 자코비안 및 동특성 불확실성을 포함하는 로봇 매니퓰레이터의 영상기반 강인제어)

  • Kim, Chin-Su;Mo, Eun-Jong;Lee, Kang-Woong
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.10
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    • pp.1047-1052
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    • 2008
  • In this paper, we design an image-based robust controller to compensate uncertainties with image Jacobian and robot dynamics due to uncertain depth measurement and load variations. The proposed controller with eye-in-hand structure has separate terms to compensate each of uncertainties. The ultimate boundedness of the closed-loop system is proved by the Lyapunov approach. The performance of the proposed control system is demonstrated by simulation and experimental results a 5-link robot manipulator with two degree of freedom.

A Robust Visual Feedback Control with Integral Compensation for Robot Manipulators (적분 보상을 포함하는 로봇 매니퓰레이터의 시각 궤환 강인 제어)

  • Lee Kang-Woong;Jie Min-Seok
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.3
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    • pp.294-299
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    • 2006
  • This paper studies a visual feedback control scheme for robot manipulators with camera-in-hand configurations. We design a robust controller that compensates for bounded parametric uncertainties of robot mechanical dynamics. In order to reduce steady state tracking error of the robot arms due to uncertain dynamics, integral action is included in the control input. Using the Lyapunov stability criterion, the uniform ultimate boundedness of the tracking error is proved. Simulation and experimental results with a 2-1ink robot manipulator illustrate the robustness and effectiveness of the proposed control algorithm.

A Robust Controller Design for Robot Manipulators with Hydraulic Actuator Dynamics (유압구동기를 채용한 로봇 매니플레이터에 대한 강인제어기 설계)

  • Park, Gwang-Seok;Hwang, Dong-Hwan
    • Proceedings of the KIEE Conference
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    • 1998.07b
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    • pp.598-600
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    • 1998
  • In this paper, a robust controller is proposed to achieve the accurate tracking for uncertain robot manipulators with hydraulic actuator dynamics. The parameter uncertainty can be quantified by the linear parameterization technique. A switching controller is proposed to guarantee the global asymptotic stability of the plant. In order to eliminate the chattering caused by the switching controller, a smoothing controller is proposed using the boundary layer technique around the sliding surface. It is shown that the smoothing controller guarantees the uniform ultimate boundedness of the tracking, error. The proposed controller shows good better tracking performance.

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Formation Dynamics of Carbon Atomic Chain from Graphene by Electron Beam Irradiation

  • Park, Hyo Ju;Lee, Zonghoon
    • Applied Microscopy
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    • v.48 no.4
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    • pp.126-127
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    • 2018
  • Carbon has numerous allotropes and various crystalline forms with full dimensionalities such as diamond, graphite, fullerenes, and carbon nanotubes leading a wide range of applications. Since the emerge of graphene consisting of a single atomic layer of carbon atoms, a fabrication of all-carbon-based device with combination of one-, two-, and three-dimensional carbons has become a hot issue. Here, we introduce an ultimate one-dimensional carbon atomic chain. Carbon atomic chains were experimentally created by removing atoms from monolayer graphene sheet under electron beam inside transmission electron microscope (TEM). A series of TEM images demonstrate the dynamics of carbon atomic chains over time from the formation, transformation, and then breakage.