• Title/Summary/Keyword: Nonlinear Systems of Equations

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SOLVABILITY FOR A CLASS OF THE SYSTEMS OF THE NONLINEAR ELLIPTIC EQUATIONS

  • Jung, Tack-Sun;Choi, Q-Heung
    • Bulletin of the Korean Mathematical Society
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    • v.49 no.1
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    • pp.1-10
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    • 2012
  • Let ${\Omega}$ be a bounded subset of $\mathbb{R}^n$ with smooth boundary. We investigate the solvability for a class of the system of the nonlinear elliptic equations with Dirichlet boundary condition. Using the mountain pass theorem we prove that the system has at least one nontrivial solution.

Nonlinear observer for flexible joint robots (유연한 관절 로보트에 대한 비선형 관측기)

  • 김윤재;임규만;함철주;함운철
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.648-653
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    • 1993
  • This paper presents an nonlinear observer scheme for flexible joint robot manipulators. This nonlinear observer scheme is based on the sliding mode method. Sliding controllers have recently been shown to feature excellent robustness and performance properties for specific classes of nonlinear tracking problems. Dynamic equations of flexible joint robot manipulators are derived from the Euler-Lagrange equations by forming the corresponding Lagrangian. Simulation results are presented to show the validness of the proposed nonlinear observer scheme.

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Dynamic Analysis of Harmonically Excited Non-Linear Structure System Using Harmonic Balance Method

  • Mun, Byeong-Yeong;Gang, Beom-Su;Kim, Byeong-Su
    • Journal of Mechanical Science and Technology
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    • v.15 no.11
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    • pp.1507-1516
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    • 2001
  • An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear structural systems. This method is based on the substructure synthesis formulation and a harmonic balance procedure, which is applied to the analysis of nonlinear responses. A complex nonlinear system is divided into substructures, of which equations are approximately transformed to modal coordinates including nonlinear term under the reasonable procedure. Then, the equations are synthesized into the overall system and the nonlinear solution for the system is obtained. Based on the harmonic balance method, the proposed procedure reduces the size of large degrees-of-freedom problem in the solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated using the study of the nonlinear rotating machine system as a large mechanical structure system. Results obtained are reported to be an efficient approach with respect to nonlinear response prediction when compared with other conventional methods.

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A Study on the Deadbeat Response Attribute of Nonlinear Systems (비선형시스템의 데드비트응답 특성 연구)

  • Song, Ja-Youn
    • Proceedings of the KIEE Conference
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    • 2001.07d
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    • pp.1993-1995
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    • 2001
  • The subject of nonlinear control is an important area of automatic control. The behavior of nonlinear systems is much more complex. If the operating range of a control system is small, and if the involved nonlinearities are smooth, then the control system may be resonably approximated by a set of linear differential equations. This paper presents the deadbeat response attribute of some nonlinear systems, e.g., magnetic levitation, pendulum, van der pol oscillator etc.. The studied results through the computer simulation are shown a promising attribute of deadbeat response that the outputs of the systems are reached relatively fast the steady state.

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Stability of Explicit Symplectic Partitioned Runge-Kutta Methods

  • Koto, Toshiyuki;Song, Eunjee
    • Journal of information and communication convergence engineering
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    • v.12 no.1
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    • pp.39-45
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    • 2014
  • A numerical method for solving Hamiltonian equations is said to be symplectic if it preserves the symplectic structure associated with the equations. Various symplectic methods are widely used in many fields of science and technology. A symplectic method preserves an approximate Hamiltonian perturbed from the original Hamiltonian. It theoretically supports the effectiveness of symplectic methods for long-term integration. Although it is also related to long-term integration, numerical stability of symplectic methods have received little attention. In this paper, we consider explicit symplectic methods defined for Hamiltonian equations with Hamiltonians of the special form, and study their numerical stability using the harmonic oscillator as a test equation. We propose a new stability criterion and clarify the stability of some existing methods that are visually based on the criterion. We also derive a new method that is better than the existing methods with respect to a Courant-Friedrichs-Lewy condition for hyperbolic equations; this new method is tested through a numerical experiment with a nonlinear wave equation.

NEWTONIAN COSMOLOGICAL PERTURBATIONS

  • Hwang, Jai-Chan
    • Publications of The Korean Astronomical Society
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    • v.7 no.1
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    • pp.107-148
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    • 1992
  • This paper presents a cosmological perturbation analysis in a Newtonian framework, using the Newtonian multi component version of the relativistic covariant equations. This work considers the fully nonlinear evolution of the perturbations, and is generalized to multicomponent systems and imperfect fluids. Known nonlinear solutions are presented in a general framework. Quasi-nonlinear analysis, considering both the compressible and rotational modes, is presented, including cases already known in the literature. The Fourier space representation of the conservation equations is also derived in a general context, with various decompositions of the velocity field. Commonly accepted cosmogonical frameworks are critically examined in the context of nonlinear evolution. This work may be regarded as the Newtonian counterpart of a recently presented general relativistic covariant formulation.

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On the Identification of Cancer-Immune Systems (암-면역 시스템의 시스템 동정에 관한 연구)

  • Lee, Kwon-Soon
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.9
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    • pp.1104-1109
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    • 1992
  • A mathematical model of cancerous system based on immunological surveillance has been proposed by Lee. The model involves a system of 12 coupled nonlinear differential equations due to cellular kinetics and each of them can be modeled bilinearly. This paper discusses only the properties of solutions to the nonlinear differential equations and identification.

Optimal Control of Nonlinear Systems Using The New Integral Operational Matrix of Block Pulse Functions (새로운 블럭펄스 적분연산행렬을 이용한 비선형계 최적제어)

  • Cho Young-ho;Shim Jae-sun
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.4
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    • pp.198-204
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    • 2003
  • In this paper, we presented a new algebraic iterative algorithm for the optimal control of the nonlinear systems. The algorithm is based on two steps. The first step transforms nonlinear optimal control problem into a sequence of linear optimal control problem using the quasilinearization method. In the second step, TPBCP(two point boundary condition problem) is solved by algebraic equations instead of differential equations using the new integral operational matrix of BPF(block pulse functions). The proposed algorithm is simple and efficient in computation for the optimal control of nonlinear systems and is less error value than that by the conventional matrix. In computer simulation, the algorithm was verified through the optimal control design of synchronous machine connected to an infinite bus.

Optimal Control of Nonlinear Systems Using Block Pulse Functions (블럭펄스 함수를 이용한 비선형 시스템의 최적제어)

  • Jo, Yeong-Ho;An, Du-Su
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.3
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    • pp.111-116
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    • 2000
  • In this paper, we presented a new algebraic iterative algorithm for the optimal control of the nonlinear systems. The algorithm is based on tow steps. The first step transforms optimal control problem into a sequence of linear optimal control problem using the quasilinearization method. In the second step, TPB(two point boundary condition problem) is solved by algebraic equations instead of differential equations using BPF(block pulse functions). The proposed algorithm is simple and efficient in computation for the optimal control of nonlinear systems. In computer simulation, the algorithm was verified through the optimal control design of Van del pole system and Volterra Predatory-prey system.

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Recent Developments in Multibody Dynamics

  • Schiehlen Werner
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.227-236
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    • 2005
  • Multibody system dynamics is based on classical mechanics and its engineering applications originating from mechanisms, gyroscopes, satellites and robots to biomechanics. Multibody system dynamics is characterized by algorithms or formalisms, respectively, ready for computer implementation. As a result simulation and animation are most convenient. Recent developments in multibody dynamics are identified as elastic or flexible systems, respectively, contact and impact problems, and actively controlled systems. Based on the history and recent activities in multibody dynamics, recursive algorithms are introduced and methods for dynamical analysis are presented. Linear and nonlinear engineering systems are analyzed by matrix methods, nonlinear dynamics approaches and simulation techniques. Applications are shown from low frequency vehicles dynamics including comfort and safety requirements to high frequency structural vibrations generating noise and sound, and from controlled limit cycles of mechanisms to periodic nonlinear oscillations of biped walkers. The fields of application are steadily increasing, in particular as multibody dynamics is considered as the basis of mechatronics.