• Title/Summary/Keyword: Analytical Integration

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Temperature change around a LNG storage predicted by a three-dimensional indirect BEM with a hybrid integration scheme

  • Shi, Jingyu;Shen, Baotang
    • Geosystem Engineering
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    • v.21 no.6
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    • pp.309-317
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    • 2018
  • We employ a three-dimensional indirect boundary element method (BEM) to simulate temperature change around an underground liquefied natural gas storage cavern. The indirect BEM (IBEM) uses fictitious heat source strength on boundary elements as basic variables which are solved from equations of boundary conditions and then used to compute the temperature change at other points in the considered problem domain. The IBEM requires evaluation of singular integration for temperature change due to heat conduction from a constant heat source on a planar (triangular) region. The singularity can be eliminated by a semi-analytical integration scheme. However, it is found that the semi-analytical integration scheme yields sharp temperature gradient for points close to vertices of triangle. This affects the accuracy of heat flux, if they are evaluated by finite difference method at these points. This difficulty can be overcome by a combination of using a direct numerical integration for these points and the semi-analytical scheme for other points distance away from the vertices. The IBEM and the hybrid integration scheme have been verified with an analytic solution and then used to the application of the underground storage.

The Study on the Determination of the Contact Area of the Circular Plate Resting on Elastic Half-space under Axisymmetric Loading (탄성지반 위의 축대칭 하중을 받는 원판의 접촉응력 해석에 관한 연구)

  • 조현영;정진환;김성철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1997.10a
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    • pp.87-94
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    • 1997
  • The circular plate resting on Boussinesq's half-space model under axisymmetric loading is studied by a finite element procedure to evaluate the distribution of contact pressure between plate and elastic half-space. The displacement of half-space due to axisymmetric surface loading can be evaluated by double integration of Boussinesq's solution. On that case the analytical integration can be executed for the radial direction but the analytical integration for the circumferential direction is impossible and the numerical integration should be considered. With the radial integration we can get non-dimensional function. Then the numerical integration for the formula is executed for the circumferential direction and the results are approximated 5th order Polynomials by using the least square method. With these 5th order approximate formula, the flexibility matrix of half-space is constructed as the coefficient matrix of nodal contact pressure by the finite element procedures. Iteration procedures are attempted by using this method to determine the separated region.

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Treatment of Numerical Integration for Boundary Element Method (경계요소법에 있어서 수치적분에 관한 고찰)

  • Park, Sung-Oan;Kwak, Chang-Sup;Koo, Young-Duk
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.2
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    • pp.185-193
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    • 1996
  • Errors included in solutions obtained by the boundary element method are generally larger than those by the finite element method in the case that the number of discreted elements is small. One of the reasons is supposed to be attributed to the error which will be produced in the numerical integration of the singular functions in two dimensional elastic problem. Then, treatment of analytical integration to reduce computing time and to decrease errors of boundary element method are proposed.

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Performance Analysis of the Clutter Map CFAR Detector with Noncoherent Integration

  • Kim, Chang-Joo;Lee, Hyuck-Jae
    • ETRI Journal
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    • v.15 no.2
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    • pp.1-9
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    • 1993
  • Nitzberg has analyzed the detection performance of the clutter map constant false alarm rate (CFAR) detector using single pulse. In this paper, we extend the detection analysis to the clutter map CFAR detector that employs M-pulse noncoherent integration. Detection and false alarm probabilities for Swerling target models are derived. The analytical results show that the larger the number of integrated pulses M, the higher the detection probability. On the other hand, the analytical results for Swerling target models show that the detection performance of the completely decorrelated target signal is better than that of the completely correlated target.

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Assessments of dissipative structure-dependent integration methods

  • Chang, Shuenn-Yih
    • Structural Engineering and Mechanics
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    • v.62 no.2
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    • pp.151-162
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    • 2017
  • Two $Chang-{\alpha}$ dissipative family methods and two $KR-{\alpha}$ family methods were developed for time integration recently. Although the four family methods are in the category of the dissipative structure-dependent integration methods, their performances may be drastically different due to the detrimental property of weak instability or overshoot for the two $KR-{\alpha}$ family methods. This weak instability or overshoot will result in an adverse overshooting behavior or even numerical instability. In general, the four family methods can possess very similar numerical properties, such as unconditional stability, second-order accuracy, explicit formulation and controllable numerical damping. However, the two $KR-{\alpha}$ family methods are found to possess a weak instability property or overshoot in the high frequency responses to any nonzero initial conditions and thus this property will hinder them from practical applications. Whereas, the two $Chang-{\alpha}$ dissipative family methods have no such an adverse property. As a result, the performances of the two $Chang-{\alpha}$ dissipative family methods are much better than for the two $KR-{\alpha}$ family methods. Analytical assessments of all the four family methods are conducted in this work and numerical examples are used to confirm the analytical predictions.

Modification of the Sloan치s Substepping Scheme for the Numerical Stress Integration of Elasto-plastic Constitutive Models (탄소성 구성 모델의 수치 응력 적분을 위한 단계분할 절차에 관한 연구)

  • 김범상;정충기
    • Geotechnical Engineering
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    • v.14 no.4
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    • pp.129-140
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    • 1998
  • Elasto-plastic finite element analysis of geotechnical boundary value problems necessitate the stress integration for the known strain increments. For the elasto-plastic constitutive model, the stress integration is generally achieved by numerical schemes, because analytical integration is impossible for general strain path. In this case, the accuracy of numerical stress integration has an important role on the overall accuracy of nonlinear finite element solution. In this study, the Sloan's substepping method which is one of explicit integration methods has been adopted and iris applicability has been checked. The unstability and inaccuracy of ifs results initiated from initial stress level were revealed. So. a new modified numerical integration method which employs the basic concept of modified Euler scheme for error control is proposed and accuracy and stability of the solutions are confirmed by triaxial test simulation.

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An Analytical Approach to Color Composition in Ray Tracing of Volume Data

  • Jung, Moon-Ryul;Paik, Doowon;Kim, Eunghwan
    • Journal of the Korea Computer Graphics Society
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    • v.2 no.1
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    • pp.1-6
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    • 1996
  • In ray tracing of 3D volume data, the color of each pixel in the image is typically obtained by accumulating the contributions of sample points on the ray cast from the pixel point. This accumulation is most naturally represented by integration. In most methods, however, it is done by numerical summation because analytical solution to the integration are hard to find. This paper shows that a semi-analytical solution can be obtained for a typical ray tracing of volume data. Tentative conclusions about the significance and usefulness of our approach are presented based on our experiments.

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Integration Issues in the GIS and Decision Support Systems

  • Jun, Chul-Min
    • Korean Journal of Geomatics
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    • v.2 no.2
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    • pp.115-122
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    • 2002
  • Since geographic information systems (GIS) began to emerge as an effective spatial information processing technology, there also has been growing interest in integrated use of GIS with other decision support systems. As various spatial-related problems such as urban development planning and natural resource management require more analytical and interpretive solutions, it is viewed that the supportive role of GIS to complement or reinforce the counterpart decision tools will be increased. This study examines the major situations that have needed the integration methodologies in the past decade to derive research trends relating to this integration agenda and, hence, to elicit the possible underlying principles from those experiences. According to the kinds of decision tools linked with GIS, alternative methodologies and viewpoints are categorized and compared.

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Analyzing Market Integration of Wild Caught Fish Species (자연산 어류의 시장 통합성 분석)

  • Kim, Do-Hoon
    • The Journal of Fisheries Business Administration
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    • v.44 no.1
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    • pp.71-79
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    • 2013
  • This study is aimed to estimate market integration of wild caught fish species on the Korean market, using both multivariate and bivariate cointegration analysis. For the analysis of market integration between wild caught fish species, major four fish species those are most popular fish in the market and caught by the large purse seine fishery-chub mackerel, jack mackerel, hairtail and spanish mackerel-were selected as analytical target fish species. And their real monthly price data from January 2000 to December 2011 were used in the analysis. The results of the multivariate cointegration test for four wild caught fish species showed that there would be long-term equilibrium relationships among prices of four wild caught fish species, and consequently, the markets for wild caught fish species were estimated to be integrated. The results of exclusion test and bivariate cointegration test also supported that there would be a clear evidence to suggest that all target wild caught fish species were cointegrated each other.