• Title/Summary/Keyword: Wave Approximation

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Uncertainty Quantification of the Experimental Spectroscopic Factor from Transfer Reaction Models

  • Song, Young-Ho;Kim, Youngman
    • Journal of the Korean Physical Society
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    • v.73 no.9
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    • pp.1247-1254
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    • 2018
  • We study the uncertainty stemming from different theoretical models in the spectroscopic factors extracted from experiments. We use three theoretical approaches, the distorted wave Born approximation (DWBA), the adiabatic distorted wave approximation (ADWA) and the continuum discretized coupled-channels method (CDCC), and analyze the $^{12}C(d,p)^{13}C$, $^{14}C(d,p)^{15}C$ reactions. We find that the uncertainty associated with the adopted theoretical models is less than 20%. We also investigate the contribution from the remnant term and observe that it gives less than 10% uncertainty. We finally make an attempt to explain the discrepancy in the spectroscopic factors of $^{17}C(\frac{3}{2}^+)$ between the ones extracted from experiments and from shell model calculations by analyzing the $^{16}C(d,p)^{17}C$ reaction.

Wavelet network approximation and coefficient learning of linear-time-varying system (시변 선형 시스템의 웨이브렛망 근사화와 가중치의 학습)

  • 이영석;김동옥;서보혁
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.728-731
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    • 1997
  • This paper discusses approximation modelling of discrete-time linear time-varying system(LTVS). The wavelet transform is considered as a tool for representing and approximating a LTVS. The joint time-frequency properties of wave analysis are appropriate for describing the LTVS. Simulation results is included to illustrate the potential application of the technique.

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Numerical Simulation of Irregular Waves Over a Shoal Using Parabolic Wave Model (포물형 파랑모형을 이용한 수중천퇴상 불규칙파의 수치모의)

  • 윤성범;이정욱;연영진;최병호
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.2
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    • pp.158-168
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    • 2001
  • A numerical model based on the wide-angle parabolic approximation equation is developed for the accurate simulation of the directional spreading and partial breaking of irregular waves. This model disintegrates the irregular waves into a series of monochromatic wave components, and the simultaneous calculations are made for each wave component. Then, the computed wave components are superposed to get the wave height of irregular waves. To consider the partial breaking of irregular waves in the computation the amount of energy dissipation due to breaking is estimated using the superposed wave height. The accuracy of the developed model is tested by comparing the numerical results with the experimental measurements reported earlier. In the case of non-breaking waves a considerable accuracy of the model is observed for both regular and irregular waves. On the contrary it is found that the accuracy is significantly degenerated for the case of breaking waves. Some analyses for the accuracy degeneration are presented.

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The Detection Method of a Target Position above a Ground Medium using the Buried Antenna (지하 매설 안테나를 이용한 지상 표적의 위치파악 기법)

  • 조정식;김채영;이승학;정종철
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.4
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    • pp.521-531
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    • 2001
  • This paper presents the extraction scheme of the scattered waves by a target above the ground using the buried antenna in a lossy and dispersive medium. The half wave dipole antennas are used to transmit and to receive a signal. The transmission line model as a feeding model is considered to take into account the effect of transmission line in a real system. The ground is modeled by the 2nd order Debye approximation with the dispersion and loss. PLRC algorithm and DPML as absorbing boundary condition are utilized to apply the 2nd order Debye approximation to FDTD. To extract the scattered wave, in addition, we employed the delay time extraction algorithm. The simulations are conducted to observe the variation of magnitude in scattered wave and detection of target position according to the change of moisture content of the lossy medium.

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Hydraulic and Numerical Experiments of Stem Waves along a Vertical Wall (직립벽을 따른 연파의 수리 및 수치실험)

  • Lee, Jong In;Yoon, Sung Bum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4B
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    • pp.405-412
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    • 2006
  • This study investigates the characteristics of stem waves along a vertical wall generated by obliquely incident monochromatic waves through laboratory experiments conducted in a wave basin and numerical simulations using parabolic approximation equations. The investigation is focused on the nonlinear effect of incident waves on the propagation characteristics of stem waves. Numerical results are compared with laboratory measurements and good agreements are obtained. The main results of this study show that the normalized stem wave height along the wall decreases and the stem width increases as the angle of incident waves decreases or the nonlinearity of the incident waves increases.

Calculation of Wave Height due to Shoaling, Refraction and Bottom Friction on a Sloping Beach (일정 경사면에서 마찰을 고려한 파랑계산)

  • 서승남;오병철
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.2 no.3
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    • pp.128-133
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    • 1990
  • An equation is presented to calculate wave height due to shoaling, refraction and bottom friction. The equation in an integral form is evaluated by two different methods: A numerical method and an analytical method based on approximation. Both methods are used to calculate wave height and show very good agreement between their results. As shown in the figure of wave height variation vs. relative water depth, an increase of incident angle leads to a decrease in wave height. For the case of normal incident wave, the present equation can be reduced, under some assumptions, to the existing equation of Bretschneider and Reid (1954).

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SH Wave Scattering from Cracks: Comparisons of Approximate and Exact Solutions (SH파의 균열 산란장 해석: 근사해와 엄밀해의 비교)

  • Jeong, Hyun-Jo;Park, Moon-Cheol;Song, Sung-Jin;Schmerr, L.W.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.4
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    • pp.354-361
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    • 2004
  • This Paper describes a crack scattering model for SH wave based on the boundary integral equation(BIE) method, where the fundamental unknown is crack opening displacement(COD). When a time harmonic plane wave was incident on a 2-D isolated crack (slit) of width 2a, the COD distributions were numerically calculated as a function of ka. The calculated COD agreed well with results obtained with other methods. The far-field scattering amplitude, which completely characterizes the flaw response, was calculated in two ways. The Kirchhoff approximation and the BIE-COD exact formulation were compared in terms of incidence angle and frequency ka in a pulse-echo mode. Maximum response was obtained for both methods at the specular reflection direction. Away from the specular direction, the Kirchhoff approximation becomes less accurate. The time domain crack response was also calculated using a band-limited spectrum of center frequency 10 MHz. At oblique incidence to the crack both methods show the existence of an antisymmetric flash points occurring from the crack edge. The Kirchhoff approximation provides an exact time interval between flash points, although it unrealistically gives the same amplitude.

A Study on the Generation for the Design Waves with a Numerical Wave Tank (수치파 수조를 이용한 설계파 생성에 관한 연구)

  • Jeong, Seong-Jae;An, Heui-Chun;Shin, Jong-Keun;Choi, Jin
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.3
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    • pp.205-211
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    • 2005
  • In this study, a new numerical procedure for the generation of a nonlinear tailored group of waves is presented. The procedure is based on the transient wave group technique. In order to integrate the nonlinearity during the wave propagation in the computational method, the Navier-Stokes equations are applied as governing equations. The governing equations are discretized by finite volume approximation. The deformation of the free water surface in each time step is pursued with a moving grid. A two-dimensional, numerical wave tank for the simulation of the wave propagation is developed and tested in detail. The numeric results are compared first with analytical wave theories and with measurements, in order to examine the correctness of the numerical wave tank. Wave surface elevation and associated fields of velocity and pressure are numerically computed and compared with measurements. Very good agreements show up.