• 제목/요약/키워드: iterative global-local analysis

검색결과 7건 처리시간 0.024초

Iterative global-local approach to consider the local effects in dynamic analysis of beams

  • Erkmen, R. Emre;Afnani, Ashkan
    • Coupled systems mechanics
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    • 제6권4호
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    • pp.501-522
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    • 2017
  • This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.

Iterative global-local procedure for the analysis of thin-walled composite laminates

  • Afnani, Ashkan;Erkmen, R. Emre
    • Steel and Composite Structures
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    • 제20권3호
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    • pp.693-718
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    • 2016
  • This paper presents a finite element procedure based on Bridging multi-scale method (BMM) in order to incorporate the effect of local/cross-sectional deformations (e.g., flange local buckling and web crippling) on the global behaviour of thin-walled members made of fibre-reinforced polymer composite laminates. This method allows the application of local shell elements in critical regions of an existing beam-type model. Therefore, it obviates the need for using computationally expensive shell elements in the whole domain of the structure, which is otherwise necessary to capture the effect of the localized behaviour. Consequently, highly accurate analysis results can be achieved with this method by using significantly smaller finite element model, compared to the existing methods. The proposed method can be used for composite polymer laminates with arbitrary fibre orientation directions in different layers of the material, and under various loading conditions. Comparison with full shell-type finite element analysis results are made in order to illustrate the efficiency and accuracy of the proposed technique.

Local-Based Iterative Histogram Matching for Relative Radiometric Normalization

  • Seo, Dae Kyo;Eo, Yang Dam
    • 한국측량학회지
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    • 제37권5호
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    • pp.323-330
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    • 2019
  • Radiometric normalization with multi-temporal satellite images is essential for time series analysis and change detection. Generally, relative radiometric normalization, which is an image-based method, is performed, and histogram matching is a representative method for normalizing the non-linear properties. However, since it utilizes global statistical information only, local information is not considered at all. Thus, this paper proposes a histogram matching method considering local information. The proposed method divides histograms based on density, mean, and standard deviation of image intensities, and performs histogram matching locally on the sub-histogram. The matched histogram is then further partitioned and this process is performed again, iteratively, controlled with the wasserstein distance. Finally, the proposed method is compared to global histogram matching. The experimental results show that the proposed method is visually and quantitatively superior to the conventional method, which indicates the applicability of the proposed method to the radiometric normalization of multi-temporal images with non-linear properties.

Bypass, homotopy path and local iteration to compute the stability point

  • Fujii, Fumio;Okazawa, Shigenobu
    • Structural Engineering and Mechanics
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    • 제5권5호
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    • pp.577-586
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    • 1997
  • In nonlinear finite element stability analysis of structures, the foremost necessary procedure is the computation to precisely locate a singular equilibrium point, at which the instability occurs. The present study describes global and local procedures for the computation of stability points including bifurcation points and limit points. The starting point, at which the procedure will be initiated, may be close to or arbitrarily far away from the target point. It may also be an equilibrium point or non-equilibrium point. Apart from the usual equilibrium path, bypass and homotopy path are proposed as the global path to the stability point. A local iterative method is necessary, when it is inspected that the computed path point is sufficiently close to the stability point.

반복 점진적 방법에 의한 2차원 단백질 분리 영상의 반점 정합 (An Iterative Spot Matching for 2-Dimensional Protein Separation Images)

  • 김정자;;김동욱;김남균;원용관
    • 대한의용생체공학회:의공학회지
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    • 제28권5호
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    • pp.601-608
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    • 2007
  • 2 Dimensional Gel Electrophoresis(2DGE) is an essentialmethodology for analysis on the expression of various proteins. For example, information for the location, mass, expression, size and shape of the proteins obtained by 2DGE can be used for diagnosis, prognosis and biological progress by comparison of patients with the normal persons. Protein spot matching for this purpose is comparative analysis of protein expression pattern for the 2DGE images generated under different conditions. However, visual analysis of protein spots which are more than several hundreds included in a 2DGE image requires long time and heavy effort. Furthermore, geometrical distortion makes the spot matching for the same protein harder. In this paper, an iterative algorithm is introduced for more efficient spot matching. Proposed method is first performing global matching step, which reduces the geometrical difference between the landmarks and the spot to be matched. Thus, movement for a spot is defined by a weighted sum of the movement of the landmark spots. Weight for the summation is defined by the inverse of the distance from the spots to the landmarks. This movement is iteratively performed until the total sum of the difference between the corresponding landmarks is larger than a pre-selected value. Due to local distortion generally occurred in 2DGE images, there are many regions in whichmany spot pairs are miss-matched. In the second stage, the same spot matching algorithm is applied to such local regions with the additional landmarks for those regions. In other words, the same method is applied with the expanded landmark set to which additional landmarks are added. Our proposed algorithm for spot matching empirically proved reliable analysis of protein separation image by producing higher accuracy.

A simple finite element formulation for large deflection analysis of nonprismatic slender beams

  • AL-Sadder, Samir Z.;Othman, Ra'ad A.;Shatnawi, Anis S.
    • Structural Engineering and Mechanics
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    • 제24권6호
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    • pp.647-664
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    • 2006
  • In this study, an improved finite element formulation with a scheme of solution for the large deflection analysis of inextensible prismatic and nonprismatic slender beams is developed. For this purpose, a three-noded Lagrangian beam-element with two dependent degrees of freedom per node (i.e., the vertical displacement, y, and the actual slope, $dy/ds=sin{\theta}$, where s is the curved coordinate along the deflected beam) is used to derive the element stiffness matrix. The element stiffness matrix in the global xy-coordinate system is achieved by means of coordinate transformation of a highly nonlinear ($6{\times}6$) element matrix in the local sy-coordinate. Because of bending with large curvature, highly nonlinear expressions are developed within the global stiffness matrix. To achieve the solution after specifying the proper loading and boundary conditions, an iterative quasi-linearization technique with successive corrections are employed considering these nonlinear expressions to remain constant during all iterations of the solution. In order to verify the validity and the accuracy of this study, the vertical and the horizontal displacements of prismatic and nonprismatic beams subjected to various cases of loading and boundary conditions are evaluated and compared with analytic solutions and numerical results by available references and the results by ADINA, and excellent agreements were achieved. The main advantage of the present technique is that the solution is directly obtained, i.e., non-incremental approach, using few iterations (3 to 6 iterations) and without the need to split the stiffness matrix into elastic and geometric matrices.

소프트웨어 글로벌화 품질관리 프레임워크 설계 및 구현 (Design and Implementation of Software Globalization Quality Management Framework)

  • 이세영
    • 정보처리학회논문지D
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    • 제19D권1호
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    • pp.29-38
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    • 2012
  • 국내 최초로 소프트웨어 글로벌화 품질관리(Globalization Quality Management, GQM) 프레임워크를 설계하고 실제 산업 현장에 적용하였다. GQM은 글로벌화 경험이 미약한 국내 소프트웨어 업체를 대상으로 글로벌화 기술 적용 결과를 국제 표준에 적합한 수준으로 끌어올리기위한 지원 및 점검을 위한 도구이다. 소프트웨어 개발 주기에 따른 체크포인트 기반의 품질관리 프로세스, 글로벌화 기술지원 모델 및 품질점검 모델로 구성된 GQM은 폭포수를 비롯한 계획주도방법론과 애자일을 포함한 반복점증방법론을 모두 지원한다. GQM에 기반하여 31개 소프트웨어 업체를 대상으로 글로벌화 수준진단을 수행하고 5점 척도로 평가한 결과, 글로벌화 역량이 2.47, 글로벌화 준비도가 2.55로 나타났다. 또한, 글로벌화 기술 도입을 위한 선결요건은 국제화 기술을 반영한 제품 설계(32.9%)와 글로벌 요구사항 분석(28%)으로 조사되었다.