• Title/Summary/Keyword: moving least square

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SIZE OPTIMIATION OF AN ENGINE ROOM MEMBER FOR CRASHWORTHINESS USING RESPONSE SURFACE METHOD

  • Oh, S.;Ye, B.W.;Sin, H.C.
    • International Journal of Automotive Technology
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    • v.8 no.1
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    • pp.93-102
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    • 2007
  • The frontal crash optimization of an engine room member using the response surface method was studied. The engine room member is composed of the front side member and the sub-frame. The thicknesses of the panels on the front side member and the sub-frame were selected as the design variables. The purpose of the optimization was to reduce the weight of the structure, under the constraint that the objective quantity of crash energy is absorbed. The response surface method was used to approximate the crash behavior in mathematical form for optimization procedure. To research the effect of the regression method, two different methodologies were used in constructing the response surface model, the least square method and the moving least square method. The optimum with the two methods was verified by the simulation result. The precision of the surrogate model affected the optimal design. The moving least square method showed better approximation than the least square method. In addition to the deterministic optimization, the reliability-based design optimization using the response surface method was executed to examine the effect of uncertainties in design variables. The requirement for reliability made the optimal structure be heavier than the result of the deterministic optimization. Compared with the deterministic optimum, the optimal design using the reliability-based design optimization showed higher crash energy absorption and little probability of failure in achieving the objective.

Optimization of Detection Method Using a Moving Average Estimator for Speech Enhancement (음성강화를 위한 이동 평균 예측량 기반의 검출방법 최적화)

  • Lee, Soo-Jeong;Shin, Kye-Hyeon;Kim, Soon-Hyob
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.3
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    • pp.97-104
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    • 2007
  • Adaptive echo canceller(AEC) has become an important component in speech communication systems, including mobile phones and speech recognition. In these applications, the acoustic echo path has a long impulse response. We propose a moving-averge least mean square(MVLMS) algorithm with a detection method for acoustic echo cancellation. Using, the result of the tests that used colored input models clearly shows that the MVLMS detection algorithm has convergence performance superior to the least mean square(LMS) detection algorithm alone. Although the computational complexity of the new MVLMS algorithm is only slightly greater than that of the standard LMS detection algorithm, the new algorithm confers a significant improvement in stability.

FCM for the Multi-Scale Problems (고속 최소자승 점별계산법을 이용한 멀티 스케일 문제의 해석)

  • 김도완;김용식
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.599-603
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    • 2002
  • We propose a new meshfree method to be called the fast moving least square reproducing kernel collocation method(FCM). This methodology is composed of the fast moving least square reproducing kernel(FMLSRK) approximation and the point collocation scheme. Using point collocation makes the meshfree method really come true. In this paper, FCM Is shown to be a good method at least to calculate the numerical solutions governed by second order elliptic partial differential equations with geometric singularity or geometric multi-scales. To treat such problems, we use the concept of variable dilation parameter.

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Analysis of a Gas Circuit Breaker Using the Fast Moving Least Square Reproducing Kernel Method

  • Lee, Chany;Kim, Do-Wan;Park, Sang-Hun;Kim, Hong-Kyu;Jung, Hyun-Kyo
    • Journal of Electrical Engineering and Technology
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    • v.4 no.2
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    • pp.272-276
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    • 2009
  • In this paper, the arc region of a gas circuit breaker (GCB) is analyzed using the fast moving least square reproducing kernel method (FMLSRKM) which can simultaneously calculate an approximated solution and its derivatives. For this problem, an axisymmetric and inhomogeneous formulation of the FMLSRKM is used and applied. The field distribution obtained by the FMLSRKM is compared to that of the finite element method. Then, a whole breaking period of a GCB is simulated, including analysis of the arc gas flow by finite volume fluid in the cell, and the electric field of the arc region using the FMLSRKM.

(4+n)-noded Moving Least Square(MLS)-based finite elements for mesh gradation

  • Lim, Jae Hyuk;Im, Seyoung
    • Structural Engineering and Mechanics
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    • v.25 no.1
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    • pp.91-106
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    • 2007
  • A new class of finite elements is described for dealing with mesh gradation. The approach employs the moving least square (MLS) scheme to devise a class of elements with an arbitrary number of nodal points on the parental domain. This approach generally leads to elements with rational shape functions, which significantly extends the function space of the conventional finite element method. With a special choice of the nodal points and the base functions, the method results in useful elements with polynomial shape functions for which the $C^1$ continuity breaks down across the boundaries between the subdomains comprising one element. Among those, (4 + n)-noded MLS based finite elements possess the generality to be connected with an arbitrary number of linear elements at a side of a given element. It enables us to connect one finite element with a few finite elements without complex remeshing. The effectiveness of the new elements is demonstrated via appropriate numerical examples.

NUMERICAL STUDY ON TWO-DIMENSIONAL INCOMPRESSIBLE VISCOUS FLOW BASED ON GRIDLESS METHOD (2차원 비압축성 점성유동에 관한 무격자법 기반의 수치해석)

  • Jeong, S.M.;Park, J.C.;Heo, J.K.
    • Journal of computational fluids engineering
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    • v.14 no.4
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    • pp.93-100
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    • 2009
  • The gridless (or meshfree) methods, such as MPS, SPH, FPM an so forth, are feasible and robust for the problems with moving boundary and/or complicated boundary shapes, because these methods do not need to generate a grid system. In this study, a gridless solver, which is based on the combination of moving least square interpolations on a cloud of points with point collocation for evaluating the derivatives of governing equations, is presented for two-dimensional unsteady incompressible Navier-Stokes problem in the low Reynolds number. A MAC-type algorithm was adopted and the Poission equation for the pressure was solved successively in the moving least square sense. Some typical problems were solved by the presented solver for the validation and the results obtained were compared with analytic solutions and the numerical results by conventional CFD methods, such as a FVM.

Analysis on a Simple Waveguide Using Meshfree Method (무요소법을 이용한 waveguide 내의 필드 분포 해석)

  • Lee, Chany;Woo, Dong-Kyun;Jung, Hyun-Kyo
    • 한국정보통신설비학회:학술대회논문집
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    • 2008.08a
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    • pp.190-192
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    • 2008
  • This paper shows the formulation of fast moving least square reproducing kernel method (FMLSRKM) which is a kind of meshfree methods. FMLSRKM has some advantages compared to conventional numerical techniques such as finite element method. For simple analysis on a rectangular waveguide, point collocation scheme is introduced and applied.

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APPLICATION OF MOVING LEAST SQUARE METHOD IN CHIMERA GRID METHOD (중첩격자에 대한 이동최소자승법 적용 연구)

  • Lee, K.;Lee, S.;Cho, J.Y.
    • Journal of computational fluids engineering
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    • v.13 no.1
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    • pp.49-56
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    • 2008
  • Chimera grid methods have been widely used in Computational Fluid Dynamics due to its simplicity in constructing grid systems over complex bodies, and suitability for unsteady flow computations with bodies in relative motion. However, the interpolation procedure for ensuring the continuity of the solution over overlapped regions fails when the so-called orphan cells are present. We have adopted the MLS(Moving Least Squares) method to replace commonly used linear interpolations in order to alleviate the difficulty associated with the orphan cells. MLS is one of the interpolation methods used in mesh-less methods. A number of examples with MLS are presented to show the validity and the accuracy of the method.

Applications of MLS(Moving Least Sqrare)-based Finite Elements for Mechanics Problems Involving Interfaces and Discontinuities (경계 및 불연속의 해결을 위한 이동최소제곱 기반 유한요소의 적용)

  • Lim Jae-Hyuk;Im Se-Young;Cho Young-Sam
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.567-574
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    • 2006
  • We present applications of MLS-based finite elements, which enable us to easily treat highly complex nonmatching finite element meshes and discontinuities. The shape functions of MLS-based finite element can be easily generated with the aid of Moving Least Square approximation on the parental domain. The major advantage includes that the position of element nodes as well as the number of the element nodes can be conveniently adjusted according to the nature of the problems under consideration, so that finite-element mesh is straightforwardly adapted to evolving discontinuities and. interfaces. Furthermore, we show that the present MLS-based finite elements are efficiently applied for elastic-plastic deformations, wherein the implicit constraint of incompressibility should be properly handled.

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APPLICATION OF MOVING LEAST SQUARE METHOD IN CHIMERA GRID METHOD (중첩격자에 대한 이동최소자승법 적용 연구)

  • Lee, K.;Lee, S.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.17-22
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    • 2007
  • Chimera grid Method is widely used in Computational Fluid Dynamics due to its simplicity in constructing grid system over complex bodies. Especially, Chimera grid method is suitable for unsteady flow computations with bodies in relative motions. However, interpolation procedure for ensuring continuity of solution over overlapped region fails when so-call orphan cells are present. We have adopted MLS(Moving Least Squares) method to replace commonly used linear interpolations in order to alleviate the difficulty associated with orphan cells. MSL is one of interpolation methods used in mesh-less methods. A number of examples with MLS are presented to show the validity and the accuracy of the method.

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