• 제목/요약/키워드: Source reconstruction

검색결과 228건 처리시간 0.023초

Rayleigh 적분의 수치해에 관한 오차분석 (Error Analysis in the Numerical Solution of Rayleigh Integral)

  • 이금원;김병기
    • 대한의용생체공학회:의공학회지
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    • 제11권1호
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    • pp.89-96
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    • 1990
  • The numerical evaluation of Rayleigh's integral for the sound source reconstruction can be speeded up by the use of angular frequency propagation method and the FFT. However, are several source of errors involved during the reconstruction. Besides the aliasing error due to undersampling in space, the wrap around error. which is caused by undersampling the kernel functionin frequency domain, and windowing effect are present. We found that there is no replicated source problem and the windowing effect is due to the windowing the kernel function In frequency domain, and, xero padding is always required to improve the quality of reconstruction.

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NUMERICAL METHODS FOR RECONSTRUCTION OF THE SOURCE TERM OF HEAT EQUATIONS FROM THE FINAL OVERDETERMINATION

  • DENG, YOUJUN;FANG, XIAOPING;LI, JING
    • 대한수학회보
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    • 제52권5호
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    • pp.1495-1515
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    • 2015
  • This paper deals with the numerical methods for the reconstruction of the source term in a linear parabolic equation from final overdetermination. We assume that the source term has the form f(x)h(t) and h(t) is given, which guarantees the uniqueness of the inverse problem of determining the source term f(x) from final overdetermination. We present the regularization methods for reconstruction of the source term in the whole real line and with Neumann boundary conditions. Moreover, we show the connection of the solutions between the problem with Neumann boundary conditions and the problem with no boundary conditions (on the whole real line) by using the extension method. Numerical experiments are done for the inverse problem with the boundary conditions.

경계요소법을 이용한 음원의 자유음장 복원에 대한 연구 (A study for the- reconstruction of free field sound source from the measured data in a closed wall by using Boundary Element Method)

  • 최한림;이덕주
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.1747-1751
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    • 2000
  • It is well known that acoustic signals, even measured in an anechoic chamber, can be contaminated due to the wall interference. Therefore, it is necessary to reconstruct the original signal from the measured data, which is very critical for the case of measurement of source signal in a water tunnel. In this thesis, new methods for the reconstruction of sound sources are proposed and validated by using Boundary Element Method from measured data in a closed space. The inverse Helmholtz integral equation and its normal derivative are used for the reconstruction of sound sources in a closed space. An arbitrary Kirchhoff surface over the sources is proposed to solve the surface information instead of direct solution for the source. Although sound sources are not directly known by the inverse Helmholtz equation, the original sound source of pressure-field outside of the wall can be indirectly obtained by using this new method.

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심자도 신호를 이용한 전류원 재구성 (Source Current Reconstruction Based on MCG Signal)

  • 권혁찬;이용호;김진목
    • Progress in Superconductivity
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    • 제4권1호
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    • pp.48-52
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    • 2002
  • When applying a SQUID system for diagnosing heart disease, it is informative to obtain the source current distributions from the measured MCG (magnetocardiogram) signals since the bioelectric activity in the heart is generally represented by distributed current sources. In order to estimate the Primary current distribution in a heart, the minimum norm estimate was computed, assuming a source plane below the chest surface. In the simulation, current distributions, which were computed for the test dipoles represented well the essential feature of the test-current configurations. Source current reconstruction was performed for MCG signal of a healthy volunteer, which was recorded using a 40-channel SQUID system in a magnetically shielded room. It was found that the obtained current distribution is consistent with the electrical activity in a heart.

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확장 Prony법을 이용한 음원 재구성특성에 관한 연구 (A Study on the Source Reconstruction Feature Usig the Extended Proy Method)

  • 이금원;김경기
    • 대한의용생체공학회:의공학회지
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    • 제11권2호
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    • pp.289-294
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    • 1990
  • In this paper, for acoustic source reconstruction using angular frequency propagation method, the extended Prony method is propsed which is useful due to not having the inherent property of DFT. The simulation is carried out and its improved results are shown explicitly by comparing with DFT case.

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MCNP-polimi simulation for the compressed-sensing based reconstruction in a coded-aperture imaging CAI extended to partially-coded field-of-view

  • Jeong, Manhee;Kim, Geehyun
    • Nuclear Engineering and Technology
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    • 제53권1호
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    • pp.199-207
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    • 2021
  • This paper deals with accurate image reconstruction of gamma camera using a coded-aperture mask based on pixel-type CsI(Tl) scintillator coupled with silicon photomultipliers (SiPMs) array. Coded-aperture imaging (CAI) system typically has a smaller effective viewing angle than Compton camera. Thus, if the position of the gamma source to be searched is out of the fully-coded field-of-view (FCFOV) region of the CAI system, artifacts can be generated when the image is reconstructed by using the conventional cross-correlation (CC) method. In this work, we propose an effective method for more accurate reconstruction in CAI considering the source distribution of partially-coded field-of-view (PCFOV) in the reconstruction in attempt to overcome this drawback. We employed an iterative algorithm based on compressed-sensing (CS) and compared the reconstruction quality with that of the CC algorithm. Both algorithms were implemented and performed a systematic Monte Carlo simulation to demonstrate the possiblilty of the proposed method. The reconstructed image qualities were quantitatively evaluated in sense of the root mean square error (RMSE) and the peak signal-to-noise ratio (PSNR). Our simulation results indicate that the proposed method provides more accurate location information of the simulated gamma source than the CC-based method.

마이크로폰 어레이를 이용한 회전하는 소음원 가시화에 관한 연구 (Study on Be-Dopplerization Technique for Rotating Source Localization)

  • 박성;이재형;최종수;김재무;이욱
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 추계학술대회논문집
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    • pp.200-204
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    • 2005
  • The use of beamforming method and de-Dopplerization technique was applied in studying the rotating sound sources. Acoustic analysis of a moving sound source required that the measured sound signals be do-Dopplerized and restored as of the original emission signals. Two main issues of the signal reconstruction in time domain are addressed herein: First, to remove Doppler effect from the measured data and to restore the original emission data of the moving source. The difference of the time domain beamforming from the frequency domain beamforming was mentioned. Also, the time domain beamforming method is deployed in the test and the comparisons were made to the frequency domain results. The time domain signal reconstruction was numerically simulated prior to the application. To validate the de-Dopplerization Performance, the rotating Point sources were examined and localized by the use of a phased array of microphone. The application of prop-rotor was conducted in a hovering condition. The results of reconstructing time signals of rotating sources and its locations were shown in the power distribution maps. In the prop-rotor measurements, the acoustic source locations were successfully verified in varying positions for different frequencies of interest.

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인코히어런트 삼각 홀로그래피에서 위상오차가 횡축방향의 해상도에 미치는 영향에 관한 연구 (Effect of Phase Error on the Lateral Resolution of Reconstruction Image in Incoherent Triangular Holography)

  • 김수길
    • 조명전기설비학회논문지
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    • 제27권11호
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    • pp.1-6
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    • 2013
  • It is introduced the phase error sources of a incoherent hologram in incoherent triangular holography and derived the reconstruction image of point-source including the phase error in the lateral direction. From the reconstruction image of point-source, we analyzed the effect of phase error on the lateral resolution. When the phase retardation errors and azimuth angle error of a wave plate and a polarizer range from 0 to $2{\pi}/15$, the normalized intensities of reconstructed images are down by about 0.1% and 2.3%, respectively.

Analysis of Effect of Phase Error Sources of Polarization Components in Incoherent Triangular Holography

  • Kim, Soo-Gil
    • Journal of the Optical Society of Korea
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    • 제16권3호
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    • pp.256-262
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    • 2012
  • We derive the point-spread function of the reconstructed image from a point-source complex hologram, which includes phase error caused by polarization components, in the longitudinal direction of the point-spread function and analyze the effect of the error sources of polarization components having influence on image reconstruction of a point-source complex hologram in incoherent triangular holography.