• Title/Summary/Keyword: Potential theory

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A new shear deformation plate theory with stretching effect for buckling analysis of functionally graded sandwich plates

  • Mahmoud, S.R.;Tounsi, Abdelouahed
    • Steel and Composite Structures
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    • v.24 no.5
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    • pp.569-578
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    • 2017
  • In this research work, a simple and accurate hyperbolic plate theory for the buckling analysis of functionally graded sandwich plates is presented. The main interest of this theory is that, in addition to incorporating the thickness stretching effect (${\varepsilon}_z{\not=}0$), the displacement field is composed only of 5 unknowns as the first order shear deformation theory (FSDT), instead of 6 like in the well-known "higher order shear and normal deformation theories". Thus, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Governing equations are obtained by employing the principle of minimum total potential energy. Comparison studies are performed to verify the validity of present results. A numerical investigation has been conducted considering and neglecting the thickness stretching effects on the buckling of sandwich plates with functionally graded skins. It can be concluded that the present theory is not only accurate but also simple in predicting the buckling response of sandwich plates with functionally graded skins.

Performance Analysis of VaR and ES Based on Extreme Value Theory

  • Yeo, Sung-Chil
    • Communications for Statistical Applications and Methods
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    • v.13 no.2
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    • pp.389-407
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    • 2006
  • Extreme value theory has been used widely in many areas of science and engineering to deal with the assessment of extreme events which are rare but have catastrophic consequences. The potential of extreme value theory has only been recognized recently in finance area. In this paper, we provide an overview of extreme value theory for estimating and assessing value at risk and expected shortfall which are the methods for modelling and measuring the extreme financial risks. We illustrate that the approach based on extreme value theory is very useful for estimating tail related risk measures through backtesting of an empirical data.

On static stability of electro-magnetically affected smart magneto-electro-elastic nanoplates

  • Ebrahimi, Farzad;Barati, Mohammad Reza
    • Advances in nano research
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    • v.7 no.1
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    • pp.63-75
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    • 2019
  • This article represents a quasi-3D theory for the buckling investigation of magneto-electro-elastic functionally graded (MEE-FG) nanoplates. All the effects of shear deformation and thickness stretching are considered within the presented theory. Magneto-electro-elastic material properties are considered to be graded in thickness direction employing power-law distribution. Eringen's nonlocal elasticity theory is exploited to describe the size dependency of such nanoplates. Using Hamilton's principle, the nonlocal governing equations based on quasi-3D plate theory are obtained for the buckling analysis of MEE-FG nanoplates including size effect and they are solved applying analytical solution. It is found that magnetic potential, electric voltage, boundary conditions, nonlocal parameter, power-law index and plate geometrical parameters have significant effects on critical buckling loads of MEE-FG nanoscale plates.

Sliding Mode Control for the Configuration of Satellite Formation Flying using Potential Functions

  • Lim, Hyung-Chul;Bang, Hyo-Choong;Kim, Hae-Dong
    • International Journal of Aeronautical and Space Sciences
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    • v.6 no.2
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    • pp.56-63
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    • 2005
  • Some methods have been presented to avoid collisions among satellites for satellite formation flying mission. The potential function method based on Lyapunov's theory is known as a powerful tool for collision avoidance in the robotic system because of its robustness and flexibility. During the last decade, a potential function has also been applied to UAV's and spacecraft operations, which consists of repulsive and attractive potential. In this study, the controller is designed using a potential function via sliding mode technique for the configuration of satellite formation flying. The strategy is based on enforcing the satellite to move along the gradient of a given potential function. The new scalar velocity function is introduced such that all satellites reach the goal points simultaneously. Simulation results show that the controller drives the satellite toward the desired point along the gradient of the potential function and is robust against external disturbances.

Consolidation Behaviour of Dredged Clay Ground Improved by Horizontal Drain Method (수평배수공법에 의해 개량된 준설점토지반의 압밀거동에 관한 연구)

  • 김형주;원명수
    • Geotechnical Engineering
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    • v.13 no.1
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    • pp.137-146
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    • 1997
  • In this study, a large consolidation test was carried out to estimate the consolidation behaviour of dredged clay ground improved by horizontal drain using plastic board drain with a vacuum pressure. The test results were analyzed by a numerical simulation using potential consolidation theory applied to a hollow cylinder. The rapid decreases in pore pressure and the drain speed in the plastic board indicate that the consolidation occurred quickly after the vacuum state was applied to the test soil. According to the numerical analysis obtained by applying the linear potential consolidation theory to a clay hollow cylinder with external radial drainage, the pore pressure is affected by the strain and the permeability of the soil rather than by the diffusion types. Therefore, measured surface settlement agreed with the numerical solution at the point where consolidation pressure increasing rate u: -0.5. Also the behaviour of the clay layer settlement in the place where the drain was installed was similar to that shown in Barron's consolidation theory. Finally, the design and construction procedure including the selection of the appropriate arrangement of horizontal drains were discussed based on the results of the laboratory tutsts. It is also shown that the potential consolidation theory make it possible to predict consolidation behaviour in the field using horizontal drains exactly.

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A Robust Algorithm for Tracking Non-rigid Objects Using Deformed Template and Level-Set Theory (템플릿 변형과 Level-Set이론을 이용한 비강성 객체 추적 알고리즘)

  • 김종렬;나현태;문영식
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.40 no.3
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    • pp.127-136
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    • 2003
  • In this paper, we propose a robust object tracking algorithm based on model and edge, using deformed template and Level-Set theory. The proposed algorithm can track objects in case of background variation, object flexibility and occlusions. First we design a new potential difference energy function(PDEF) composed of two terms including inter-region distance and edge values. This function is utilized to estimate and refine the object shape. The first step is to approximately estimate the shape and location of template object based on the assumption that the object changes its shape according to the affine transform. The second step is a refinement of the object shape to fit into the real object accurately, by using the potential energy map and the modified Level-Set speed function. The experimental results show that the proposed algorithm can track non-rigid objects under various environments, such as largely flexible objects, objects with large variation in the backgrounds, and occluded objects.

The Effect of Inorganic Electrolyte on the Electrokinetic Features of Calcium Carbonate Particles in Aqueous Environment (수중 탄산칼슘 입자의 전기적 거동에 미치는 무기염류의 영향)

  • O, Se-Jin;Choi, Eun-Jin;Kim, Dong-Su
    • Journal of Korean Society on Water Environment
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    • v.26 no.1
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    • pp.89-95
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    • 2010
  • The electrokinetic potential of $CaCO_3$, which takes an important part in aquatic system, has been measured and the variation of total energy between $CaCO_3$ particles with the distance of particles was estimated based on DLVO theory. The electrokinetic potential of particles was observed to increase to positive direction as the charge valence of cations which was added to suspension was increased. Also, the total interaction energy between particles was estimated to be more negative as the charge valence of cation was higher and its concentrations was raised. When a mixture of cations with different charge valences was added, the influence of cation with a higher charge valence was more significant on the total interaction energy between particles. When anion was added to the suspension of $CaCO_3$, the total energy estimated by DLVO theory was examined to move to positive direction and the electrokinetic potential of particles became more negative. Likewise cations, the effect of anions on the electrokinetic potential of particles and total interaction energy between them was observed to be proportional to their charge valence and the influence of the mixture of anions with different charge valence became more remarkable as the mixing ratio of the anion with a higher charge valence was increased.

A Study on Predicting the Potential for Bid-Rigging among Bidders using FTT in Public Construction Projects (FTT를 활용한 입찰실무자의 입찰담합 가능성 예측 연구)

  • Cho, Jin-Ho;Shin, Young-Su;Kim, Byung-Soo
    • Korean Journal of Construction Engineering and Management
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    • v.24 no.6
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    • pp.36-44
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    • 2023
  • The aim of this study is to predict the potential for bid-rigging among public construction bidders and develop preventive and responsive measures. By employing the Fraud Triangle Theory (FTT), which considers the factors of opportunity, pressure, and rationalization, we analyze and explore the bid-rigging potential among construction industry professionals. A survey is conducted among General and specialized construction firms to validate the FTT research model and predict individual bid-rigging tendencies. The results indicate that higher levels of pressure, greater opportunities, and stronger rationalization increase the likelihood of individual bid-rigging. Moreover, more opportunities and stronger rationalization also raise the potential for bid-rigging by others. Understanding these dynamics enhances our knowledge and contributes to the development of policies aimed at preventing bid-rigging.

Effective Hamiltonian Study on the Valence States of NH and $NH^+$

  • Jong Keun Park;Hosung Sun
    • Bulletin of the Korean Chemical Society
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    • v.11 no.1
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    • pp.34-41
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    • 1990
  • The second order ab initio effective valence shell Hamiltonian is calculated for the valence state potential energy curves of NH and $NH^+$. From the potential energy curves various spectroscopic constants of valence states are determined. The results are in good agreement with experiments and configuration interaction calculations. They show the composite picture of potential energy curves and also indicate that the second order effective Hamiltonian theory is adequate for describing various valence states of a molecule and its ions simultaneously.

HEAT EQUATION WITH A GEOMETRIC ROUGH PATH POTENTIAL IN ONE SPACE DIMENSION: EXISTENCE AND REGULARITY OF SOLUTION

  • Kim, Hyun-Jung;Lototsky, Sergey V.
    • Communications of the Korean Mathematical Society
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    • v.34 no.3
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    • pp.757-769
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    • 2019
  • A solution of the heat equation with a distribution-valued potential is constructed by regularization. When the potential is the generalized derivative of a $H{\ddot{o}}lder$ continuous function, regularity of the resulting solution is in line with the standard parabolic theory.