• Title/Summary/Keyword: Scattering Analysis

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Mode conversion and scattering analysis of guided waves at delaminations in laminated composite beams

  • Soleimanpour, Reza;Ng, Ching-Tai
    • Structural Monitoring and Maintenance
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    • v.2 no.3
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    • pp.213-236
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    • 2015
  • The paper presents an investigation into the mode conversion and scattering characteristics of guided waves at delaminations in laminated composite beams. A three-dimensional (3D) finite element (FE) model, which is experimentally verified using data measured by 3D scanning laser vibrometer, is used in the investigation. The study consists of two parts. The first part investigates the excitability of the fundamental anti-symmetric mode ($A_0$) of guided wave in laminated composite beams. It is found that there are some unique phenomena, which do not exist for guided waves in plate structures, make the analysis become more complicated. The phenomena are observed in numerical study using 3D FE simulations. In the second part, several delaminated composite beams are studied numerically to investigate the mode conversion and scattering characteristics of the $A_0$ guided wave at delaminations. Different sizes, locations and through-thickness locations of the delaminations are investigated in detail. The mode conversion and scattering phenomena of guided waves at the delaminations are studied by calculating reflection and transmission coefficients. The results show that the sizes, locations and through-thickness locations of the delaminations have significant effects on the scattering characteristics of guided waves at the delaminations. The results of this research would provide better understanding of guided waves propagation and scattering at the delaminations in the laminated composite beams, and improve the performance of guided wave damage detection methods.

Reactive Ion Scattering of Low Energy Cs+ from Surfaces. A Technique for Surface Molecular Analysis

  • Kang, Heon
    • Bulletin of the Korean Chemical Society
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    • v.32 no.2
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    • pp.389-398
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    • 2011
  • Although the currently available surface spectroscopic techniques provide powerful means of studying atoms and simple molecules on surfaces, the identification of complex molecules and functional groups is a major concern in surface analysis. This article describes a recently developed method of surface molecular analysis based on reactive ion scattering (RIS) of low energy (< 100 eV) $Cs^+$ beams. The RIS method can detect surface molecules via a mechanism in which a $Cs^+$ projectile picks up an adsorbate from the surface during the scattering process. The basic principles of the method are reviewed and its applications are discussed by showing several examples from studies of molecules and their reactions on surfaces.

An assessment of the applicability of multigroup cross sections generated with Monte Carlo method for fast reactor analysis

  • Lin, Ching-Sheng;Yang, Won Sik
    • Nuclear Engineering and Technology
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    • v.52 no.12
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    • pp.2733-2742
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    • 2020
  • This paper presents an assessment of applicability of the multigroup cross sections generated with Monte Carlo tools to the fast reactor analysis based on transport calculations. 33-group cross section sets were generated for simple one- (1-D) and two-dimensional (2-D) sodium-cooled fast reactor problems using the SERPENT code and applied to deterministic steady-state and depletion calculations. Relative to the reference continuous-energy SERPENT results, with the transport corrected P0 scattering cross section, the k-eff value was overestimated by 506 and 588 pcm for 1-D and 2-D problems, respectively, since anisotropic scattering is important in fast reactors. When the scattering order was increased to P5, the 1-D and 2-D problem errors were increased to 577 and 643 pcm, respectively. A sensitivity and uncertainty analysis with the PERSENT code indicated that these large k-eff errors cannot be attributed to the statistical uncertainties of cross sections and they are likely due to the approximate anisotropic scattering matrices determined by scalar flux weighting. The anisotropic scattering cross sections were alternatively generated using the MC2-3 code and merged with the SERPENT cross sections. The mixed cross section set consistently reduced the errors in k-eff, assembly powers, and nuclide densities. For example, in the 2-D calculation with P3 scattering order, the k-eff error was reduced from 634 pcm to -223 pcm. The maximum error in assembly power was reduced from 2.8% to 0.8% and the RMS error was reduced from 1.4% to 0.4%. The maximum error in the nuclide densities at the end of 12-month depletion that occurred in 237Np was reduced from 3.4% to 1.5%. The errors of the other nuclides are also reduced consistently, for example, from 1.1% to 0.1% for 235U, from 2.2% to 0.7% for 238Pu, and from 1.6% to 0.2% for 241Pu. These results indicate that the scalar flux weighted anisotropic scattering cross sections of SERPENT may not be adequate for application to fast reactors where anisotropic scattering is important.

Analysis of Electromagnetic Wave Scattering from a Sea Surface Using a Monte-Carlo FDTD Technique

  • Choi Dong-Muk;Kim Che-Young;Kim Dong-Il;Jeon Joong-Sung
    • Journal of electromagnetic engineering and science
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    • v.5 no.2
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    • pp.87-91
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    • 2005
  • This paper presents a Monte-Carlo FDTD technique to determine the scattered field from a perfectly conducting surface like a sea surface, from which the useful information on the incoherent pattern tendency could be observed. A one-dimensional sea surface used to analysis scattering was generated using the Pierson-Moskowitz model. In order to verify the numerical results by this technique, these results are compared with those of the small perturbation method, which show a good match between them. To investigate the incoherent pattern tendency involved, the dependence of the back scattering coefficients on the different wind speed(U) is discussed for the back scattering case.

Analysis of Scattering Characteristics of the Rectangular Waveguide with a Horizontal Conducting Post using Mode Matching Method and Generalized Scattering Method (모드매칭법과 일반산란계수법을 이용한 수평 금속봉을 갖는 구형 도파관의 산란 특성 해석)

  • 김원기;김상태;신철재
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.7
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    • pp.698-705
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    • 2004
  • In this paper, we present the analysis method for a rectangular waveguide with horizontal conducting post using mode matching method and generalized scattering method. Scattering characteristics of a rectangular waveguide with the horizontal conducting post according to radius and height of the post are simulated by the proposed method. The simulated results by proposed method show good agreement with the measured results and the HFSS's results. Proposed method are easily applied to the design of a waveguide component with horizontal conducting posts.

Numerical Analysis of Back Scattering from a Target over a Random Rough Surface Using DRTM

  • Yoon, Kwang-Yeol
    • Journal of electromagnetic engineering and science
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    • v.10 no.2
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    • pp.61-66
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    • 2010
  • This paper is concerned with an analysis of the back scattering of electromagnetic waves from a target moving along random rough surfaces such as the desert, and sea. First, the discrete ray tracing method(DRTM) is introduced, and then, this method is applied to the back scattering problem in order to investigate the effect of the back scattering from random rough surfaces on the electric field intensities. Finally, numerical examples of various height deviations of the Gaussian type of rough surfaces are shown. It is numerically demonstrated that the back scattering is dominated by the diffractions related to the reflections from the random rough surfaces.

An Experimental Analysis on Dark-field Laser Scattering for the Surface Inspection of Infrared Cut-off Filters (적외선차단필터의 표면 검사를 위한 암시야 레이저산란에 대한 실험적 분석)

  • Kim, Gyung-Bum;Han, Jae-Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.11
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    • pp.76-83
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    • 2007
  • The dark-field laser scattering system has been developed to inspect surface defects in infrared cut-off filters and then laser scattering characteristics against the defects are investigated. The qualitative analysis for the reliable and accurate detection performance is described through the correlation between incident angles of a laser and viewing ones of a camera. In this paper, reliable and important information with laser scattering is given for the surface defect inspection of IR filters. Its performance has been verified through various experiments.

The Scattering Analysis for the Sphere in Water (수중에서 구형 산란체에 의한 음의 산란 해석)

  • 김관주;김재환;유상욱
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.622-628
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    • 1998
  • The SONAR(SOund NAvigation and Ranging) is the system that detects objects and finds their locations in water by using the echo ranging technique. In this paper, the scattering phenomena for a rigid spherical scatterer will be analyzed using closed form solution, Boundary Element Method and Finite Element Method. Scattering analysis for an elastic spherical scatterer will be analyzed, later. In oder to analyzing the sound wave scattering phenomena for an elastic scatterer in water coupled problem between acoustic and vibration must be considered.

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High-frequency Back-scattering Cross Section Analysis of Rotating Targets (회전 표적의 고주파수 후방산란단면적 해석)

  • Kim, Kook-Hyun;Cho, Dae-Seung;Kim, Jin-Hyeong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.3
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    • pp.16-24
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    • 2007
  • The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

Light Scattering Analysis on Coagulation Detection with Magnetic Particles

  • Nahm, Kie B.
    • Current Optics and Photonics
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    • v.2 no.6
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    • pp.623-628
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    • 2018
  • Clotting properties of human blood are important clinical information to monitor for patients with platelet and coagulation disorders. Most devices used to diagnose these disorders utilize blood plasma together with tissue factors and $Ca^{{+}{+}}$ additives. In some instruments, magnetic particles were mixed with blood samples and a rotating magnetic field was applied, resulting in the rotation of magnetic particles, which was probed by impinging light. The working principle seems obvious yet had not been investigated in depth. We modeled the collective behavior of light propagating through magnetic needles, aligned in the direction of the rotating external magnetic field, with scattering light analysis software. Simulation results indicated that the scattering pattern undergoes periodic undulations with respect to the slant angle of the magnetic needles. Also provided is a means of extracting meaningful information from the scattering measurement.