• Title, Summary, Keyword: Alpha theory

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$\alpha$-$\beta$Current and Power Components Analysis of Instantaneous Power Theory Using MATLAB/SIMULINK (MATLAB/SIMULIN에 의한 순시전력이론의 $\alpha$-$\beta$ 전류 및 전력성분 해석)

  • 정영국;임영철
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.14 no.3
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    • pp.88-96
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    • 2000
  • The instantaneous power theory have been considered as efficient theory in recent years, because it is easier to understand numerical representation and more soft to control PWM power converter on $\alpha$-$\beta$ stationary reference frame. From the forgoing theory, with regard to the calculating process of compensating reference current, there are many induced components of current/ power, and these components have consequently influence on physical interpretation of instantaneous power theory. Especially, beginners for studing the instantaneous power theory don't have enough informations for standard waveform of induced $\alpha$-$\beta$ components. Therefore, this paper describes simulation works using MATLAB/SIMULINK for $\alpha$-$\beta$ space trajectories and waveforms of $\alpha$-$\beta$ current and power components, induced from the instantaneous power theory. It is respected that the results in this paper are serviceable as basic information to assist beginner for studing the instantaneous power theory.

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NEW CONVERGENCE CONDITIONS OF SECANT METHODS VIA ALPHA THEORY

  • KIM, S.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.5 no.2
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    • pp.101-115
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    • 2001
  • Recent theoretical analysis of numerical methods for solving nonlinear systems of equations is represented by alpha theory of Newton method developed Smale et al. The theory was extended to Secant method by providing convergence conditions by Yakoubsohn which the Secant method is treated as an operator defined for analytical functions. We use Secant methods as an iterative scheme with approximations, which results in new convergence conditions. We compare the two conditions and show that the new conditions represent the features of Secant method in a more precise way.

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Some Calculated (p,α) Cross-Sections Using the Alpha Particle Knock-On and Triton Pick-Up Reaction Mechanisms: An Optimisation of the Single-Step Feshbache-Kermane-Koonin (FKK) Theory

  • Olise, Felix S.;Ajala, Afis;Olaniyi, Hezekiah B.
    • Nuclear Engineering and Technology
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    • v.48 no.2
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    • pp.482-494
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    • 2016
  • The Feshbache-Kermane-Koonin (FKK) multi-step direct (MSD) theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,${\alpha}$) reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core) by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process) and proton-triton (for the pick-up process) interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy.

On the general volodin space

  • Park, Sang-Gyu;Song, Yong-Jin
    • Communications of the Korean Mathematical Society
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    • v.10 no.3
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    • pp.699-705
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    • 1995
  • We first generalize the Volodin space which Volodin constructed in order to define a new algebraic K-theory. We investigate the topological (homotopy) properties of the general Volodin space. We also provide a theorem which seems to be useful in pure homotopy theory. We prove that $V(*_\alpha G_\alpha, {G_\alpha})$ is simply connected.

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DFT Study on the Different Oligomers of Glycerol (n=1-4) in Gas and Aqueous Phases

  • Valadbeigi, Younes;Farrokhpour, Hossein
    • Journal of the Korean Chemical Society
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    • v.57 no.6
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    • pp.684-690
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    • 2013
  • Since a glycerol molecule has three active sites, two ${\alpha}$ and one ${\beta}$ hydroxyl groups; it undergoes condensation by releasing water molecules to produce linear, nonlinear and heterocyclic oligomers. The Gibbs free energy (G), enthalpy (H) and internal energy (E) of 7 diglycerol, 15 triglycerol and 23 tetraglycerol isomers were calculated at B3LYP level of theory using 6-311++G(d, p) basis set, in both gas and aqueous phases. Linear oligomers, ${\alpha}{\alpha}$-diglycerol, ${\alpha}{\alpha}$, ${\alpha}{\alpha}$-triglycerol and ${\alpha}{\alpha}$, ${\alpha}{\alpha}$, ${\alpha}{\alpha}$-tetraglycerol, were found to be the most stable oligomers in aqueous phase. It was found that the stability of cyclic oligomers decreases as the size of their rings increases. Cyclic oligomers are produced by dehydration of the acyclic ones which is an endothermic reaction while its ${\Delta}G$ is negative. The dehydration reaction is less endothermic in aqueous phase.

Effects of Silane Structure on Composite Interaction Parameter (αC)) of Silica Filled Rubber Compounds (실란 구조가 실리카 복합소재 내 구조발달 상호계수(αC)에 미치는 영향)

  • Kim, Sung Min;Kim, Kwang Jea
    • Polymer(Korea)
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    • v.38 no.4
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    • pp.411-416
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    • 2014
  • Due to the polar characteristics of silica compared to carbon black, the degree of silica dispersion, which affects the mechanical properties of rubber compounds, is an important issue. Wolff first introduced the in-rubber structure of particles (${\alpha}_F$) to express the structure development in the compounds; however, with the introduction of bifunctional silanes, his theory could not explain the 3-dimensional network structure of the compounds. Later his theory was expanded to express the composite interaction parameter (in-rubber structure of the compound) (${\alpha}_C$), which included Wolff's filler-filler interaction parameter (${\alpha}_F$), however, there was no reported experimental result proving the theory. This research first experimentally expressed the in-rubber structure of the compound ${\alpha}_C$ (= ${\alpha}_F+{\alpha}_{FP}$(filler-silane-rubber interaction parameter) + ${\alpha}_P$ (rubber-rubber interaction parameter)) upon mono- and bifunctional silane treated silica filled natural rubber (NR) compounds. Using different structure silanes, i.e. PTES, OTES, TESPD, and TESPT, the ${\alpha}_C$ value of each compound was measured and calculated. The ${\alpha}_C$ value of TESPT treated silica filled compound was 1.64, which composed of ${\alpha}_F$ (0.99), ${\alpha}_{FP}$ (0.31), and ${\alpha}_P$ (0.34).

The Flow Analysis of Supercavitating Cascade by Nonlinear Theory (비선형이론에 의한 Supercavitation 익렬의 유동해석)

  • Pak, Ee-Tong;Hwang, Yoon
    • Solar Energy
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    • v.17 no.1
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    • pp.35-46
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    • 1997
  • In this study comparison of experiment results with the computed results of linear theory and nonlinear theory using singularity method was obtainable. Specially singularity points like sources and vortexes on hydrofoil and freestreamline were distributed to analyze two dimensional flow field of supercavitating cascade using nonlinear theory, and governing equations of flow field were derived and hydraulic characteristics of cascade were calculated by numerical analysis of the governing equations. The results compared linear theory and nonlinear theory with the experiment results of the study are as follows: The tolerances of nonlinear theory were larger than those of linear theory in case of ${\alpha}<10^{\circ}$. Moreover the computational range of attack angles could be expanded from ${\alpha}=10^{\circ}$ to ${\alpha}=25^{\circ}$, the flow field of supercavitating cascade could be analyzed in the condition which the wake thickness and the length of cavity are a variable. The shapes of cavity were changed sensitively according to various variable such as attack angles, pitches and wake thickness, and the pressure distribution of hydrofoil surface was identical almost disregarding wake thickness but changed largely according to attack angle and the length of cavity. Lift coefficient and drag coefficient were reduced according to increasing of wake thickness but the influences of wake thickness were very little in the situation of small pitch and long cavity.

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A NOTE ON THE DISPERSION RELATION OF THE MODIFIED BOUSSINSQ EQUATIONS

  • Cho, Yong-Sik;Lee, Chang-hoon
    • Water Engineering Research
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    • v.1 no.4
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    • pp.293-298
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    • 2000
  • Optimal values of $\alpha$ characterizing the linear dispersion property in the modified Boussinesq equations are determined by minimizing the combined relative errors of the phase and group velocities. The value of $\alpha$ is fixed in previous studies, whereas it is varying in the present study. The phase and group velocities are calculated by using variable $\alpha$ and compared to those of the linear Stokes wave theory and previous studies. It is found that the present study produces the best match to the linear Stokes theory.

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ROLLING STONES WITH NONCONVEX SIDES I: REGULARITY THEORY

  • Lee, Ki-Ahm;Rhee, Eun-Jai
    • Journal of the Korean Mathematical Society
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    • v.49 no.2
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    • pp.265-291
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    • 2012
  • In this paper, we consider the regularity theory and the existence of smooth solution of a degenerate fully nonlinear equation describing the evolution of the rolling stones with nonconvex sides: $\{M(h)=h_t-F(t,z,z^{\alpha}h_{zz})\;in\;\{0<z{\leq}1\}{\times}[0,T] \\ h_t(z,t)=H(h_z(z,t),h)\;{on}\;\{z=0\}$. We establish the Schauder theory for $C^{2,{\alpha}}$-regularity of h.

Numerical Resistivity Modeling Using Alpha Center Theory: A Case History for Field Resistivity Data (Alpha center를 이용한 전기비저항 수치 모델링 : 현장 탐사 자료에 대한 적용 예)

  • 윤왕중
    • Tunnel and Underground Space
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    • v.7 no.4
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    • pp.334-340
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    • 1997
  • Alpha center theory which was first proposed by Stefanescu has been proved to be effective for the detection of the location of the conductive orebody. A numerical forward modeling was conducted to verify the effectiveness of this method. Field works were carried out along the three profiles in two different areas for the purpose of finding fractured zone which might be accompanied with the presence of the groundwater. And the results were modeled by alpha center method, which was later testified by wellproven 2-dimensional finite difference inversion scheme. Field data could be successfully modeled with this alpha center algorithm, especially for the smooth-varying resistivity models. For the abrupt change of the resistivity values, the alpha center coefficients have a tendency to be negative to simulate the steep resistivity gradients. This method is quite simple and easy for the future applications. The numerical calculation can be performed very quickly with the personal computers.

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