• 제목/요약/키워드: Smooth and non-smooth function

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Limit analysis of plates-a finite element formulation

  • Capsoni, Antonio;Corradi, Leone
    • Structural Engineering and Mechanics
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    • 제8권4호
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    • pp.325-341
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    • 1999
  • A procedure for the computation of the load carrying capacity of perfectly plastic plates in bending is presented. The approach, based on the kinematic theorem of limit analysis, requires the evaluation of the minimum of a convex, but non-smooth, function under linear equality constraints. A systematic solution procedure is devised, which detects and eliminates the finite elements which are predicted as rigid in the collapse mechanism, thus reducing the problem to the search for the minimum of a smooth and essentially unconstrained function of nodal velocities. Both Kirchhoff and Mindlin plate models are considered. The effectiveness of the approach is illustrated by means of some examples.

A Level-Set Method for Simulation of Drop Motions

  • Son, Gi-Hun;Hur, Nahm-Keon;Suh, Young-Ho;Lee, Sang-Hyuk
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년도 학술대회
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    • pp.340-346
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    • 2008
  • A level-set method is developed for computation of drop motions in various engineering applications. Compared with the volume-of-fluid method based on a non-smooth volume-fraction function, the LS method can calculate an interface curvature more accurately by using a smooth distance function. Also, it is straightforward to implement for two-phase flows in complex geometries unlike the VOF method requiring much more complicated geometric calculations. The LS method is applied to simulation of inkjet process, thin film pattering and droplet collisions.

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A Level-Set Method for Simulation of Drop Motions

  • Son, Gi-Hun;Hur, Nahm-Keon;Suh, Young-Ho;Lee, Sang-Hyuk
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년 추계학술대회논문집
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    • pp.340-346
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    • 2008
  • A level-set method is developed for computation of drop motions in various engineering applications. Compared with the volume-of-fluid method based on a non-smooth volume-fraction function, the LS method can calculate an interface curvature more accurately by using a smooth distance function. Also, it is straightforward to implement for two-phase flows in complex geometries unlike the VOF method requiring much more complicated geometric calculations. The LS method is applied to simulation of inkjet process, thin film pattering and droplet collisions.

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CURVES WITH MAXIMAL RANK, BUT NOT ACM, WITH VERY HIGH GENERA IN PROJECTIVE SPACES

  • Ballico, Edoardo
    • 대한수학회지
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    • 제56권5호
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    • pp.1355-1370
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    • 2019
  • A curve $X{\subset}\mathbb{P}^r$ has maximal rank if for each $t{\in}\mathbb{N}$ the restriction map $H^0(\mathcal{O}_{\mathbb{P}r}(t)){\rightarrow}H^0(\mathcal{O}_X(t))$ is either injective or surjective. We show that for all integers $d{\geq}r+1$ there are maximal rank, but not arithmetically Cohen-Macaulay, smooth curves $X{\subset}\mathbb{P}^r$ with degree d and genus roughly $d^2/2r$, contrary to the case r = 3, where it was proved that their genus growths at most like $d^{3/2}$ (A. Dolcetti). Nevertheless there is a sector of large genera g, roughly between $d^2/(2r+2)$ and $d^2/2r$, where we prove the existence of smooth curves (even aCM ones) with degree d and genus g, but the only integral and non-degenerate maximal rank curves with degree d and arithmetic genus g are the aCM ones. For some (d, g, r) with high g we prove the existence of reducible non-degenerate maximal rank and non aCM curves $X{\subset}\mathbb{P}^r$ with degree d and arithmetic genus g, while (d, g, r) is not realized by non-degenerate maximal rank and non aCM integral curves.

NUFLEX를 이용한 다상유동의 수치해석 (NUMERICAL ANALYSIS OF MULTIPHASE FLOW BY NUFLEX)

  • 유태진;서영호;손기헌;허남건
    • 한국전산유체공학회지
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    • 제12권2호
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    • pp.21-25
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    • 2007
  • A general purpose program NUFLEX has been extended for two-phase flows with topologically complex interface and cavitation flows with liquid-vapor phase change caused by large pressure drop. In analysis of two-phase flow, the phase interfaces are tracked by employing a LS(Level Set) method. Compared with the VOF(Volume-of-Fluid) method based on a non-smooth volume-fraction function, the LS method can calculate an interfacial curvature more accurately by using a smooth distance function. Also, it is quite straightforward to implement for 3-D irregular meshes compared with the VOF method requiring much more complicated geometric calculations. Also, the cavitation process is computed by including the effects of evaporation and condensation for bubble formation and collapse as well as turbulence in flows. The volume-faction and continuity equations are adapted for cavitation models with phase change. The LS and cavitation formulation are implemented into a general purpose program for 3-D flows and verified through several test problems.

비평활 발전비용함수를 가진 동적 경제급전문제의 교환 최적화 (A Swap Optimization for Dynamic Economic Dispatch Problem with Non-smooth Function)

  • 이상운
    • 한국컴퓨터정보학회논문지
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    • 제17권11호
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    • pp.189-196
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    • 2012
  • 본 논문은 동적 경제급전의 최적화 문제를 풀기 위해 교환 알고리즘을 제안하였다. 제안된 알고리즘은 첫 번째로, 발전단가 $C_i^{max}/P_i^{max}$가 비싼 발전기는 가동을 중지시키는 개념을 도입하여 총 요구량 $P_d$와 총 발전량 ${\Sigma}P_i$의 균형을 맞추었다. 다음으로 발전량을 $P_i=P_i{\pm}{\Delta}$, (${\Delta}$=1.0, 0.1, 0.01, 0.001)에 대해 $_{max}[F(P_i)-F(P_i-{\Delta})]$ > $_{min}[F(P_j+{\Delta})-F(P_j)]$, $i{\neq}j$이면 $P_i=P_i-{\Delta}$, $P_j=P_j+{\Delta}$로 발전량을 교환하는 방법을 적용하였다. 동적 경제급전 문제의 시험사례에 제안된 알고리즘을 적용한 결과 기존의 휴리스틱 알고리즘 최적화 발전비용을 크기 감소시켜 경제적인 이익을 극대화 시켰다.

A Data Hiding Scheme for Grayscale Images Using a Square Function

  • Kwon, Hyejin;Kim, Haemun;Kim, Soonja
    • 한국멀티미디어학회논문지
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    • 제17권4호
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    • pp.466-477
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    • 2014
  • Many image hiding schemes based on least significant bit (LSB) transformation have been proposed. One of the LSB-based image hiding schemes that employs diamond encoding was proposed in 2008. In this scheme, the binary secret data is converted into base n representation, and the converted secret data is concealed in the cover image. Here, we show that this scheme has two vulnerabilities: noticeable spots in the stego-image, i.e., a non-smooth embedding result, and inefficiency caused by rough re-adjustment of falling-off-boundary value and impractical base translation. Moreover, we propose a new scheme that is efficient and produces a smooth and high quality embedding result by restricting n to power of 2 and using a sophisticated re-adjustment procedure. Our experimental results show that our scheme yields high quality stego-images and is secure against RS detection attack.

AN INEQUALITY OF SUBHARMONIC FUNCTIONS

  • Kim, Young-Ho
    • Journal of applied mathematics & informatics
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    • 제5권2호
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    • pp.525-537
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    • 1998
  • In this paper we prove the inequality of subharmonic functions between a non-negative subharmonic function u and a smooth function $\upsilon$satisfying |$\upsilon(0)$\mid$\leq u(0), $\mid$\nabla \upsilon $\mid$ \leq$\mid$\nabla u $\mid$\leq c\Delta u $, where 0$\leq$c$\leq$1 is a constant. Here $\mu$is the harmonic measure on $\partial$D with respect to 0.

MULTIPLICITY AND STABILITY OF SOLUTIONS FOR SEMILINEAR ELLIPTIC EQUATIONS HAVING NOT NON-NEGATIVE MASS

  • Kim, Wan-Se;Ko, Bong-Soo
    • 대한수학회지
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    • 제37권1호
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    • pp.85-109
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    • 2000
  • In this paper, the multiplicity, stability and the structure of classical solutions of semilinear elliptic equations of the form (equation omitted) will be discussed. Here $\Omega$ is a smooth and bounded domain in $R^{n}$ (n $\geq$ 1), f(x,u) = │u│$^{\alpha}$/sgn(u)-h(x), 0 < $\alpha$ < 1, (n $\geq$ 1) and h is a ${\gamma}$- Holder continuous function on $\Omega$ for some 0 < ${\gamma}$ < 1.a}$ < 1.

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Performance Comparison of CEALM and NPSOL

  • Seok, Hong-Young;Jea, Tahk-Min
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2001년도 ICCAS
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    • pp.169.4-169
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    • 2001
  • Conventional methods to solve the nonlinear programming problem range from augmented Lagrangian methods to sequential quadratic programming (SQP) methods. NPSOL, which is a SQP code, has been widely used to solve various optimization problems but is still subject to many numerical problems such as convergence to local optima, difficulties in initialization and in handling non-smooth cost functions. Recently, many evolutionary methods have been developed for constrained optimization. Among them, CEALM (Co-Evolutionary Augmented Lagrangian Method) shows excellent performance in the following aspects: global optimization capability, low sensitivity to the initial parameter guessing, and excellent constraint handling capability due to the benefit of the augmented Lagrangian function. This algorithm is ...

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