• Title/Summary/Keyword: ideal boundary

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Cross-Border Interactions in the Swiss - German - French Border Region (스위스.독일.프랑스 접경지역에서의 월경적(越境的) 상호작용)

  • Kim Boo-Sung
    • Journal of the Korean Geographical Society
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    • v.41 no.1 s.112
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    • pp.22-38
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    • 2006
  • This paper is to explore the cross-border interactions and the formation of trans-boundary regional identity in the Swiss-German-French border region. It begins with a brief review of recent studies on 'boundary and border region', in order to gain a insight into the theoretical debates on this theme and to find out ideal types of the cross-border co-operations. And then it deals with the everyday cross-border movements(working, shopping, living) in 'Regio TriRhena', discussing the development of the trans-boundary co-operations in the EuroRegion 'Upper Rhine'. There are several committees to be defined in trans-boundary co-operation on the 'Upper Rhine', with different scopes of action, structured collectively like Russian dolls(Babushka principle). The economic differences between 3 countries trigger massive cross-border movements. This paper attempts to organize these cross-border interactions around Ullman's 3 bases for spatial interaction(complementarity, transferability, intervening opportunity). In conclusion, this paper shows that the elimination of economic obstacles does not suffice to create trans-boundary identity or a trans-border common regional spirit.

COMPUTATION OF THE DYNAMIC FORCE COMPONENT ON A VERTICAL CYLINDER DUE TO SECOND ORDER WAVE DIFFRACTION

  • Bhatta, Dambaru
    • Journal of applied mathematics & informatics
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    • v.26 no.1_2
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    • pp.45-60
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    • 2008
  • Here we consider the evaluation of the the dynamic component of the second order force due to wave diffraction by a circular cylinder analytically and numerically. The cylinder is fixed, vertical, surface piercing in water of finite uniform depth. The formulation of the wave-structure interaction is based on the assumption of a homogeneous, ideal, incompressible, and inviscid fluid. The nonlinearity in the wave-structure interaction problem arises from the free surface boundary conditions, namely, dynamic and kinematic free surface boundary conditions. We expand the velocity potential and free surface elevation functions in terms of a small parameter and then consider the second order diffraction problem. After deriving the pressure using Bernoulli's equation, we obtain the analytical expression for the dynamic component of the second order force on the cylinder by integrating the pressure over the wetted surface. The computation of the dynamic force component requires only the first order velocity potential. Numerical results for the dynamic force component are presented.

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Dynamic Analysis of Rectangular Liquid Storage Containers Considering Fluid-Structure Interaction effects (유체-구조물 상호작용 효과를 고려한 직사각형 단면의 수조구조물의 동적 해석)

  • 박장호;권기준
    • Journal of the Korean Society of Safety
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    • v.15 no.3
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    • pp.96-101
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    • 2000
  • The effects of internal fluid motion have to be considered in the analysis of liquid storage containers. Therefore this thesis developed a three-dimensional boundary element-finite element method for the analysis of rectangular liquid storage containers. The irrotational motion of inviscid and incompressible ideal fluid is modeled by using boundary elements and the motion of structure by finite elements. Coupling is performed by using compatibility and equilibrium conditions along the interface. Dynamic response characteristics of rectangular liquid storage containers such as sloshing motion, hydrodynamic pressure, displacement by fluid-structure interaction are investigated.

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Profile Design of the Inner Rotor of a Gerotor by the Composite Curve of Circular Arcs (원호조합곡선에 의한 제로터 내부로터의 형상설계)

  • Lee Sung-Chul
    • Tribology and Lubricants
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    • v.22 no.2
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    • pp.79-86
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    • 2006
  • As the gerotor set with ideal profile meshes too tight, the reduction in the size of the rotor is generally adopted for a smooth operation. In this paper, a method of the profile modification for providing clearances was proposed. The meshing properties of the gerotor were analyzed and the non-boundary section of the inner rotor was identified, which denoted that the adjacent chambers were in the same pressure state. Clearances were imposed on the non-boundary section of the inner rotor, and then the profile of that section was modified as a composite curve of arcs. The other sections of the inner rotor were also interpolated as arcs. Thus, the whole profile of the inner rotor was designed as a composite curve of arcs.

Hydroelastic Vibration Analysis of Two Circular Plates with Simply Supported Boundary Condition (단순지지된 두 원판의 유체연성 고유진동 해석)

  • 정경훈;이규만;박근배
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.603-608
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    • 2001
  • This paper deals with the free vibration of two identical circular plates coupled with a bounded fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. In the theory, it is assumed that the ideal fluid is filled between the two plates and the plates are simply supported along the plate edges. The proposed method is verified by the finite element analysis using commercial software with an excellent accuracy. The effect of the plate boundary conditions on the fluid-coupled natural frequency is investigated.

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Modelling of magneto-thermoelastic plane waves at the interface of two prestressed solid half-spaces without energy dissipation

  • Kakar, Rajneesh;Kakar, Shikha
    • Earthquakes and Structures
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    • v.8 no.6
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    • pp.1299-1323
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    • 2015
  • A model for reflection and refraction of magneto-thermoelastic SV-waves at the interface of two transversely isotropic and homogeneous solid half spaces under initial stress by applying classical dynamical theory of thermoelasticity is purposed. The reflection and refraction coefficients of SV-waves are obtained with ideal boundary conditions for SV-wave incident on the solid-solid interface. The effects of magnetic field, temperature and initial stress on the amplitude ratios after numerical computations are shown graphically with MATLAB software for the particular model.

Iris Image Enhancement for the Recognition of Non-ideal Iris Images

  • Sajjad, Mazhar;Ahn, Chang-Won;Jung, Jin-Woo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.4
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    • pp.1904-1926
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    • 2016
  • Iris recognition for biometric personnel identification has gained much interest owing to the increasing concern with security today. The image quality plays a major role in the performance of iris recognition systems. When capturing an iris image under uncontrolled conditions and dealing with non-cooperative people, the chance of getting non-ideal images is very high owing to poor focus, off-angle, noise, motion blur, occlusion of eyelashes and eyelids, and wearing glasses. In order to improve the accuracy of iris recognition while dealing with non-ideal iris images, we propose a novel algorithm that improves the quality of degraded iris images. First, the iris image is localized properly to obtain accurate iris boundary detection, and then the iris image is normalized to obtain a fixed size. Second, the valid region (iris region) is extracted from the segmented iris image to obtain only the iris region. Third, to get a well-distributed texture image, bilinear interpolation is used on the segmented valid iris gray image. Using contrast-limited adaptive histogram equalization (CLAHE) enhances the low contrast of the resulting interpolated image. The results of CLAHE are further improved by stretching the maximum and minimum values to 0-255 by using histogram-stretching technique. The gray texture information is extracted by 1D Gabor filters while the Hamming distance technique is chosen as a metric for recognition. The NICE-II training dataset taken from UBRIS.v2 was used for the experiment. Results of the proposed method outperformed other methods in terms of equal error rate (EER).

Analysis on Thermal Boundary Resistance at the Interfaces in Superlattices by Using the Molecular Dynamics (분자동역학법을 이용한 초격자 내부의 경계면 열저항의 해석)

  • Choi, Soon-Ho;lee, Jung-Hye;Choi, Hyun-Kue;Yoon, Seok-Hun;Oh, Cheol;Kim, Myoung-Hwan
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1382-1387
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    • 2004
  • From the viewpoint of a macro state, there is no thermal boundary resistance (TBR) at an interface if both surfaces at an interface are perfectly contacted. However, recent molecular dynamics (MD) studies reported that there still exists the TDR at the interface in an ideal epitaxial superlttice. Our previous studies suggested the model to predict the TBR not only quantitatively also qualitatively in superlattices. The suggested model was based on the classical theory of a wave reflection, and provided highly satisfactory results for an engineering purpose. However, it was not the complete model because our previous model was derived by considering only the effects from a mass ratio and a potential ratio of two species. The interaction of two species presented by the Lennard-Jones (L-J) potential is governed by the mutual ratio of the masses, the potential well depths, and the diameters. In this study, we performed the preliminary simulations to investigate the effect resulting from the diameter ratio of two species for the completion of our model and confirmed that it was also a ruling factor to the TBR at an interface in superlattices.

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Natural vibrations and hydroelastic stability of laminated composite circular cylindrical shells

  • Bochkareva, Sergey A.;Lekomtsev, Sergey V.
    • Structural Engineering and Mechanics
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    • v.81 no.6
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    • pp.769-780
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    • 2022
  • This paper studies the dynamic behavior of laminated composite circular cylindrical shells interacting with a fluid. The mathematical formulation of the dynamic problem for an elastic body is developed based on the variational principle of virtual displacements and the relations of linear elasticity theory. The behavior of an ideal compressible fluid is described by the potential theory, the equations of which together with boundary conditions are transformed to a weak form. The hydrodynamic pressure exerted by the fluid on the internal surface of the shell is calculated according to the linearized Bernoulli equation. The numerical implementation of the mathematical formulation has been done using the semi-analytical finite element method. The influence of the ply angle and lay-up configurations of laminated composites on the natural vibration frequencies and the hydroelastic stability boundary have been analyzed for shells with different geometrical dimensions and under different kinematic boundary conditions set at their edges. It has been found that the optimal value of the ply angle depends on the level of filling of the shell with a fluid. The obtained results support the view that by choosing the optimal configuration of the layered composite material it is possible to change upwards or downwards the frequency and mode shape, as well as the critical velocity for stability loss over a wide range.

The Flow Analysis of Jeju Harbor using Moving Boundary Technique (이동경계기법을 이용한 제주항의 유동해석)

  • Kim, Nam-Hyeong;Park, Ji-Hun
    • Journal of Navigation and Port Research
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    • v.27 no.5
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    • pp.539-546
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    • 2003
  • The numerical model of the flow analysis by finite element technique is described. The Galerkin method is employed for spatial discretization Two step explicit finite element scheme is used to discretize the time function, which has advantage in problems treating large numbers of elements and unsteady state. Two dimensional hydrodynamic model considering moving boundary condition is developed. Also it applied flow model which develop on flow portion of ideal fluid in the model flume and verified, and the results of this study confirm the efficiency of moving boundary treatment in Jeju harbor. The computed results have shown the good adaptability of moving boundary condition From these studies, it can be concluded that the present method is a useful and effective tool in tidal flow analysis.