• Title/Summary/Keyword: global coupling

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GLOBAL COUPLING EFFECTS ON A FREE BOUNDARY PROBLEM FOR THREE-COMPONENT REACTION-DIFFUSION SYSTEM

  • Ham, Yoon-Mee
    • Journal of the Korean Mathematical Society
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    • v.43 no.3
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    • pp.659-676
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    • 2006
  • In this paper, we consider three-component reaction-diffusion system. With an integral condition and a global coupling, this system gives us an interesting free boundary problem. We shall examine the occurrence of a Hopf bifurcation and the stability of solutions as the global coupling constant varies. The main result is that a Hopf bifurcation occurs for global coupling and this motion is transferred to the stable motion for strong global coupling.

A HOPF BIFURCATION IN AN ATTRACTION-ATTRACTION CHEMOTAXIS SYSTEM WITH GLOBAL COUPLING

  • YoonMee Ham
    • Korean Journal of Mathematics
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    • v.31 no.2
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    • pp.203-216
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    • 2023
  • We consider a bistable attraction-attraction chemotaxis system with global coupling term. The study in this paper asserts that conditions for chemotactic coefficients for attraction and attraction and the global coupling constant to show existence of stationary solutions and Hopf bifurcation in the interfacial problem as the bifurcation parameters vary are obtained analytically.

Seismic performance evaluation of coupled core walls with concrete and steel coupling beams

  • Fortney, Patrick J.;Shahrooz, Bahram M.;Rassati, Gian A.
    • Steel and Composite Structures
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    • v.7 no.4
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    • pp.279-301
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    • 2007
  • When coupling beams are proportioned appropriately in coupled core wall (CCW) systems, the input energy from ground motions is dissipated primarily through inelastic deformations in plastic hinge regions at the ends of the coupling beams. It is desirable that the plastic hinges form at the beam ends while the base wall piers remain elastic. The strength and stiffness of the coupling beams are, therefore, crucial if the desired global behavior of the CCW system is to be achieved. This paper presents the results of nonlinear response history analysis of two 20-story CCW buildings. Both buildings have the same geometric dimensions, and the components of the buildings are designed based on the equivalent lateral force procedure. However, one building is fitted with steel coupling beams while the other is fitted with diagonally reinforced concrete coupling beams. The force-deflection relationships of both beams are based on experimental data, while the moment-curvature and axial load-moment relationships of the wall piers are analytically generated from cross-sectional fiber analyses. Using the aforementioned beam and wall properties, nonlinear response history analyses are performed. Superiority of the steel coupling beams is demonstrated through detailed evaluations of local and global responses computed for a number of recorded and artificially generated ground motions.

Buckling Strength Analysis of Box-Column Including the Coupling Effect Between Local and Global Buckling

  • Paik, Jeom-K.
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1988.10a
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    • pp.36-42
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    • 1988
  • In this study, a formulation of the idealized plate element based upon the idealized structural unit method(ISUM) firstly proposed by Ueda et.al is made in an attempt to analyze the geometric nonlinear behaviour up to the buckling strength of thin-walled long structures like box-column structure including the coupling effect between local and global buckling. An application to the example box-column is also performed and it is found that the present method gives reliable results with consuming very short computing times and therefore is very useful for evaluation of the buckling strength of thin-walled long structures.

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Free Vibration Analysis of Simply-Supported Rectangular Plate with a Circular Cutout by Independent Coordinate Coupling Method (독립좌표연성법을 이용한 원형 구멍을 갖는 단순지지 직사각형 평판의 자유진동해석)

  • Kwak, Moon-K.;Han, Sang-Bo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1177-1182
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    • 2006
  • This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have be en many methods developed for the free vibration of the rectangular plate with a rectangular cutout., very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian co ordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

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Free Vibration Analysis of Simply-supported Rectangular Plate with a Circular Cutout by Independent Coordinate Coupling Method (독립좌표연성법을 이용한 원형 구멍을 갖는 단순지지 직사각형 평판의 자유진동해석)

  • Kwak, Moon-K.;Han, Sang-Bo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.6 s.111
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    • pp.643-650
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    • 2006
  • This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have been many methods developed for the free vibration of the rectangular plate with a rectangular cutout, very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian coordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

GRADIENT PROJECTION METHODS FOR THE n-COUPLING PROBLEM

  • Kum, Sangho;Yun, Sangwoon
    • Journal of the Korean Mathematical Society
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    • v.56 no.4
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    • pp.1001-1016
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    • 2019
  • We are concerned with optimization methods for the $L^2$-Wasserstein least squares problem of Gaussian measures (alternatively the n-coupling problem). Based on its equivalent form on the convex cone of positive definite matrices of fixed size and the strict convexity of the variance function, we are able to present an implementable (accelerated) gradient method for finding the unique minimizer. Its global convergence rate analysis is provided according to the derived upper bound of Lipschitz constants of the gradient function.

Study of Collective Synchronous Dynamics in a Neural Network Model

  • Cho, Myoung Won
    • Journal of the Korean Physical Society
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    • v.73 no.9
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    • pp.1385-1392
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    • 2018
  • A network with coupled biological neurons provides various forms of collective synchronous dynamics. Such phase-locking dynamics states resemble eigenvectors in a linear coupling system in that the forms are determined by the symmetry of the coupling strengths. However, the states behave as attractors in a nonlinear dynamics system. We here study the collective synchronous dynamics in a neural system by using a novel theory. We exhibit how the period and the stability of individual phase-locking dynamics states are determined by the characteristics of synaptic couplings. We find that, contrary to common sense, the firing rate of a synchronized state decreases with increasing synaptic coupling strength.

Controll over the Au@Ag Core-shell Nanoparticle 2D Patterns via Diblock Copolymer Inverse Micelle Templates and Investigation of the Surface Plasmon Based Optical Property (이중블록공중합체 역마이셀 주형을 이용한 Au@Ag 코어-쉘 나노입자 2차원 패턴 제어 및 표면 플라즈몬 기반 광학적 특성 연구)

  • Yoon, Min Ji;Kim, Jihyeon;Jang, Yoon Hee;Lee, Ji-Eun;Chung, Kyungwha;Quan, Li Na;Kim, Dong Ha
    • Journal of the Korean Chemical Society
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    • v.57 no.5
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    • pp.618-624
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    • 2013
  • We demonstrated unique inter- and intra-plasmonic coupling effects in bimetallic Au@Ag core-shell NP arrays which are regularly or randomly arranged on self-assembled block copolymer (BCP) inverse micelle monolayers. Polyvinylpyrrolidone (PVP)-stabilized Au@Ag core-shell NP arrays in regular or disordered configuration were incorporated and assembled on reconstructed PS-b-P4VP inverse micelle templates through two types of processes. The intensively enhanced LSPR coupling properties of individual and assembled Au@Ag NPs were evaluated by UV-visible spectroscopy in terms of the type of ligand stabilizer, coupling between Au and Ag, thickness of Ag shell, and type of array configuration. Finally, Au@Ag core-shell NP arrays were employed as active substrates for surface enhanced Raman spectroscopy (SERS) and a significantly enhanced signal enhancement was observed in accordance with the coupling intensity of Au@Ag NPs patterns.

The Resonance of Marine Propulsion Shaft System excited by Diesel Engine (디젤엔진의 가진에 의한 선박용 추진 축계의 공진)

  • Lee, D.C.;Kang, B.Y.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.10a
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    • pp.248-253
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    • 2009
  • The propulsion system which apply the diesel engine with reduction gear as prime mover, generally installs the elastic coupling between engine and intermediate shaft, This coupling can isolate the vibratory torque excited by diesel engine, or the excess transient torque and moment occurring by external impact. So, diesel engine and reduction gear can safely operate by elastic coupling. Unfortunately, the elastic coupling for skimmer vessel was repeatedly broken by unknown vibration during the sea trial In this paper, the authors are searching for the possibilities and causes of the elastic coupling failure, via the global vibration measurement and the past incident investigation.

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