• Title/Summary/Keyword: Numerical Investigation

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STRUCTURE OF THE ZEROS OF q-BERNOULLI POLYNOMIALS

  • RYOO C. S.
    • Journal of applied mathematics & informatics
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    • v.17 no.1_2_3
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    • pp.49-58
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    • 2005
  • In this paper we observe the structure of the roots of q-Bernoulli polynomials, ${\beta}_n(w,h{\mid}q)$, using numerical investigation. By numerical experiments, we demonstrate a remarkably regular structure of the real roots of ${\beta}_n(w,h{\mid}q)$ for $-{\frac{1}{5}},-{\frac{1}{2}}$. Finally, we give a table for numbers of real and complex zeros of ${\beta}_n(w,h{\mid}q)$.

Transformation of Irregular Waves Propagating through Slit Caisson (슬릿 케이슨을 통과하는 불규칙파의 변형)

  • Min, Hyun-Seong;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.159-162
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    • 2007
  • The numerical efforts are presented for investigation of irregular waves passing a slit cassion and a warock block breakwater. In the numerical model, the Reynolds equations are solved by a finite difference method and $k-\varepsilon$ model is employed for the turbulence analysis. To track the free surface displacement, the volume of fluid method(VOF) is employed. Numerical predictions of reflection and transmission coefficients are compared with those of the warock block breakwater with the slit caisson. Energy dissipation and seawater exchange rates of the slit caisson are better than those of the warock block breakwater.

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Numerical Analysis on the Thermal Choking Process In a Model SCRamjet Engine (모델 스크림제트 연소기내의 열질식과정 수치해석)

  • Moon, G.W.;Choi, J.Y.;Jeung, I.S.
    • 한국연소학회:학술대회논문집
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    • 2000.05a
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    • pp.76-84
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    • 2000
  • A numerical study was conducted for the investigation of thermal choking process in a model scramjet engine based on the experimental results at the Australian National University. The results of numerical simulation showed that thermal choking process could be related to the interaction between hypersonic flow and fuel-air mixing process. Especially, we could make sure that turbulent mixing was most important parameter to the thermal choking process.

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Investigation on the Prediction Performance of the Chemical Kinetics for the Numerical Simulation of MILD Combustion (마일드 연소장 수치계산을 위한 화학반응기구의 예측성능 검토)

  • Kim, Yu Jeong;Oh, Chang Bo
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.341-344
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    • 2012
  • The prediction performance of the chemical kinetics for the numerical simulation of MILD combustion was investigated. A wall-confined turbulent methane jet combustor was adopted as a configuration. Four chemical kinetics, such as a global 3-step, WD4, Skeletal, and DRM-19, were investigated, The air stream of the wall-confined MILD jet combustor was diluted with combustion products. It was found that the DRM-19 was optimal for the numerical simulation of the MILD combustion.

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Numerical Investigation of 2DCD Nozzle Flow Having a Secondary Jet Injection for Thrust Vector Control (추력벡터제어를 위한 이차 분사유동이 있는 2DCD 노즐 내부의 수치적 연구)

  • Lee JinGyu;Chang KeunShik
    • 한국전산유체공학회:학술대회논문집
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    • 2002.10a
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    • pp.17-22
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    • 2002
  • A numerical solution procedure has been developed to analyze the flow field resulted from the injection of a transverse jet through the divergent flap of a 2DCD nozzle for thrust vector control. The formulation employs the compressible Navier-Stokes equations in conservation law form and a two equation $\kappa-\omega$ turbulence model. Detailed numerical results are presented in this paper for the 2DCD nozzle over a range of secondary to primary injection mass flow ratios and nozzle pressure ratios.

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Experimental and numerical investigation of composite conical shells' stability subjected to dynamic loading

  • Jalili, Sina;Zamani, Jamal;Shariyat, M.;Jalili, N.;Ajdari, M.A.B.;Jafari, M.
    • Structural Engineering and Mechanics
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    • v.49 no.5
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    • pp.555-568
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    • 2014
  • In this article, stability of composite conical shells subjected to dynamic external pressure is investigated by numerical and experimental methods. In experimental tests, cross-ply glass woven fabrics were selected for manufacturing of specimens. Hand-layup method was employed for fabricating the glass-epoxy composite shells. A test-setup that includes pressure vessel and data acquisition system was designed. Also, numerical analyses are performed. In these analyses, effect of actual geometrical imperfections of experimental specimens on the numerical results is investigated. For introducing the imperfections to the numerical models, linear eigen-value buckling analyses were employed. The buckling modes are multiplied by very small numbers that are derived from measurement of actual specimens. Finally, results are compared together while a good agreement between results of imperfect numerical analyses and experimental tests is observed.

Numerical Investigation of an Unconditionally Stable Compact 2D FDTD Based on the Alternating-Direction Implicit Scheme

  • Saehoon Ju;Jeongnam Cheon;Kim, Hyung-Hoon;Kim, Hyeongdong
    • Journal of electromagnetic engineering and science
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    • v.3 no.1
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    • pp.39-44
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    • 2003
  • An unconditionally stable compact 2D Alternating-Direction Implicit (ADI) FDTD method for calculating dispersion characteristics of waveguide structures is proposed. The numerical stability and numerical dispersion relation of the proposed method are also presented and discussed. Numerical wavelengths for the dominant and higher order modes in a hollow waveguide are obtained from numerical simulations and compared with those from the analytical dispersion relation. The numerical results show that the proposed scheme has the potential to successfully analyze a class of waveguides having locally fine geometry with reduced numerical costs.

Numerical Study of Contaminant Transport Coupled with Large Strain Consolidation

  • Lee, Jang-Guen
    • Journal of The Korean Society of Agricultural Engineers
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    • v.50 no.2
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    • pp.45-52
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    • 2008
  • Contaminant transport has been widely studied in rigid porous media, but there are some cases where a large volumetric stain occurs such as dewatering of dredged contaminated sediment, landfill liner, and in-situ capping. This paper presents a numerical investigation of contaminant transport coupled with large strain consolidation. Consolidation test was performed with contaminated sediments collected in Gary, Indiana, U.S. to obtain constitutive relationships, which are required for numerical simulations. Numerical results using CST2 show an excellent agreement with measured settlement and excess pore pressure. CST2 is then used to simulate contaminant transport during and after in-situ capping. Numerical simulations provide that transient advective flows caused by consolidation significantly increase the contaminant transport rate. In addition, the numerical simulations revealed that active capping with Reactive Core Mat (RCM) significantly decelerates consolidation-induced contaminant transport.

Numerical and Experimental Investigation of Thermal Behavior of a Radiation Heater for Flip-Chip Bonders (플립칩 본더용 복사형 히터의 열특성 해석 및 시험)

  • Lee, Sang-Hyun;Kwak, Ho-Sang;Han, Chang-Soo;Ryu, Do-Hyun
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1645-1650
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    • 2003
  • A numerical and experimental study is made of thermal behavior of a hot chuck which is specially designed for flip-chip bonders. The hot chuck consists of radiant heat sources and a heated plate of very high conductivity, which is for achievement of high-speed heat-up. A simplified numerical model is developed to simulate unsteady thermal behavior of the heated plate. Parallel experimental work is also conducted for a prototype of the hot chuck. Based on the experimental data, the numerical model is tuned to improve the reliability and accuracy. Design analysis using the numerical model is conducted. The results of numerical computations illustrate that the radiant heater system adopted in this study satisfies the key design requirements for a high-performance hot chuck.

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