• Title/Summary/Keyword: Geoacoustic Parameters

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Geoacoustic Parameters Inversion Using Parallel Multi-Population Genetic Algorithm (병렬 다중 개체군 유전 알고리즘을 이용한 지음향 파라미터 역산)

  • Oh Taekhwan;Na Jungyul;Lee Seongwook;Kim Seongil;Park Joung-Soo
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.6
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    • pp.309-316
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    • 2005
  • This paper Presents the geoacoustic inversion with Parallel Multi-Population Genetic Algorithm (PMPGA). This method is the modified form of simple genetic algorithm (SGA), which is devised for complementing the defects of simple genetic algorithm. The light bulb source and vertical line array (VLA) receiver are used for geoacoustic inversion. The results of this study show the geoacoustic Parameters can be estimated by PMPGA and the proposed algorithm is 1.7 times as fast as serial one on an average.

Influence of the Geoacoustic Parameters of Seabed Appearing in the Broadband Interference Pattern by Moving Targets (이동 표적에 의한 광대역 간섭패턴의 지음향 인자 영향)

  • Hahn, Joo-Young;Lee, Hyeong-Uk;Lee, Bong-Ki
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.3
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    • pp.43-50
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    • 2007
  • A range-frequency interference pattern is analyzed in the course of the propagation of ship noise in shallow water. It has been shown to exhibit striated bands of intensity maxima and minima in the spectrogram. The slope of the striations is an invariant of the modal interference and is described by a waveguide invariant parameter $\beta$. It turns out that this interference pattern is useful for identifying the physical properties of the waveguide such as seabed properties. In this article, the interference pattern is analyzed using image processing techniques to produce the distribution of the beta and the effects of sediment types and geoacoustic parameters on beta distribution are examined and characterized by moments of the distributions.

Geoacoustic Inversion via Transmission Loss Matching and Matched Field Processing (전달손실 비교를 통한 지음향학적 인자 역산과 정합장처리)

  • Kim Kyungseop;Park Cheolsoo;Kim Seongil;Seong Woojae
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.6
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    • pp.325-333
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    • 2005
  • This paper proposes a geoacoustic inversion method for the experimental data or MAPLE 2004 experiment conducted in the East Sea of Korea in 2004 and shows source tracking test results to validate the Proposed inversion method. An objective function is defined as a correlation function of the measured and the simulated transmission loss data. The measured transmission data were obtained using a multi-tonal towed source and VLA. The VFSA (Very Fast Simulated Annealing) is applied to the inversion Problem which optimizes the objective function. After performing the inversion process for the S frequencies tonal data independently. geoacoustic models are constructed. Finally matched-field source tracking is Performed using the inverted parameters to verify them.

Time-Domain Geoacoustic Inversion via Light Bulb Source Signal Matching (전구음원 신호를 이용한 시간영역 지음향학적 인자 역산)

  • Kim Kyungseop;Park Cheolsoo;Kim Seongil;Seong Woojae
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.6
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    • pp.334-342
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    • 2005
  • In this Paper. a time-domain geoacoustic inversion was performed using the bulb signals measured during MがU. 04 experiment conducted in the East Sea of Korea in 2004. An obiective function was defined as a direct cross-correlation between the measured and the simulated signals in time domain. The ray theory was used to model the wave propagation in time domain and optimizations were Performed using VFSA (very fast simulated annealing) algorithm. Comparison of inversion results with those from transmission loss matching (an accompanying paper in this issue of the Journal of the Acoustical Society of Korea) shows that Parameters are consistently inverted. Direct time series comparisons between the measured signals and the simulated signals are Presented based on inversion results.

Geoacoustic Velocity of Basement and Tertiary Successions of the Okgye and Bukpyeong Coast, East Sea (동해 옥계, 북평 연안 기반암의 지음향 속도와 제3기 퇴적층)

  • Ryang, Woo-Hun;Kwon, Yi-Kyun;Jin, Jae-Hwa;Kim, Hyun-Tae;Lee, Chi-Won
    • Journal of the Korean earth science society
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    • v.28 no.3
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    • pp.367-373
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    • 2007
  • A geoacoustic modeling has been developed to predict sound transmission through the submarine layers of sediment and rock. It demands a geoacoustic model with the measured, extrapolated, and predicted values of geoacoustic parameters controlling acoustic propagation. In the coastal areas of Okgye and Bukpyeong, the East Sea, the marine succession consists of Quaternary/Tertiary deposits and acoustic basement. The basement of Okgye coastal area is indicative of siliciclastics of the Pyeongan Group in Paleozoic, and the average velocities of P-wave and S-wave are 4276 m/s and 2400 m/s, respectively. The basement of Bukpyeong coastal area is indicative of limestone of the Joseon Supergroup in early Paleozoic, and the average velocities of P-wave and S-wave are 5542 m/s and 2742 m/s, respectively.

High-Frequency Bottom Loss Measured at Near-Normal Incidence Grazing Angle in Jinhae Bay (진해만에서 측정된 높은 수평입사각에서의 고주파 해저면 반사손실)

  • La, Hyoung-Sul;Park, Chi-Hyung;Cho, Sung-Ho;Choi, Jee-Woong;Na, Jung-Yul;Yoon, Kwan-Seob;Park, Kyung-ju;Park, Joung-Soo
    • The Journal of the Acoustical Society of Korea
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    • v.29 no.4
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    • pp.223-228
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    • 2010
  • High-frequency bottom loss measurements for grazing angle of $82^{\circ}$ in frequency range 17-40 kHz were made in Jinhae bay in the southern part of Korea. Observations of bottom loss showed the strong variation as a function of frequency, which were compared to the predicted values using two-layered sediment reflection model. The geoacoustic parameters including sound speed, density and attenuation coefficient for the second sediment layer were predicted from the empirical relations with the mean grain size obtained from sediment core analysis. The geoacoustic parameters for the surficial sediment layer were inverted using Monte Carlo inversion algorithm. A sensitivity study for the geoacoustic parameters showed that the thickness of surficial sediment layer was most sensitive to the variation of the bottom loss.

Inverse Estimation of Geoacoustic Parameters in Shallow Water Using tight Bulb Sound Source (천해환경에서 전구음원을 이용한 지음향인자의 역추정)

  • 한주영;이성욱;나정열;김성일
    • The Journal of the Acoustical Society of Korea
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    • v.23 no.1
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    • pp.8-16
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    • 2004
  • An inversion method is presented for the determination of the compressional wave speed, compressional wave attenuation, thickness of the sediment layer and density as a function of depth for a horizontally stratified ocean bottom. An experiment for estimating those properties was conducted in the shallow water of South Sea in Korea. In the experiment, a light bulb implosion and the propagating sound were measured using a VLA (vertical line array). As a method for estimating the geoacoustic properties, a coherent broadband matched field processing combined with Genetic Algorithm was employed. When a time-dependent signal is very short, the Fourier transform results are not accurate, since the frequency components are not locatable in time and the windowed Fourier transform is limited by the length of the window. However, it is possible to do this using the wavelet transform a transform that yields a time-frequency representation of a signal. In this study, this transform is used to identify and extract the acoustic components from multipath time series. The inversion is formulated as an optimization problem which maximizes the cost function defined as a normalized correlation between the measured and modeled signals in the wavelet transform coefficient vector. The experiments and procedures for deploying the light bulbs and the coherent broadband inversion method are described, and the estimated geoacoustic profile in the vicinity of the VLA site is presented.

Measurements of Mid-frequency Bottom Loss in Shallow Water of the Yellow Sea (서해 천해환경에서의 중주파수 해저면 반사손실 측정)

  • Yoon, Young Geul;Lee, Changil;Choi, Jee Woong;Cho, Sungho;Oh, Suntaek;Jung, Seom-Kyu
    • The Journal of the Acoustical Society of Korea
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    • v.34 no.6
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    • pp.423-431
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    • 2015
  • KIOST-HYU joint acoustics experiment was performed on the western shallow water off the Taean peninsula in the Yellow Sea in May 2013. In this paper, mid-frequency (6~16 kHz) bottom loss data measured in a grazing angle range of $17{\sim}60^{\circ}$ are presented and compared to the predictions obtained using a Rayleigh reflection model. The sediment structure of the experimental site was characterized by multi-layered sediment and the components of the surficial sediment consisted of various types of particles with a mean grain size of $5.9{\phi}$. The model predictions obtained using the mean grain size were not in agreement with the measured bottom loss, and those obtained using the grain size of $4{\phi}$, which was estimated by an inversion process, showed a best fit to the measurements. It would be because the standard deviation of the gain-size distribution of surficial sediment is $4.3{\phi}$, which is much larger than those of other areas around the experimental site. Finally, the model predictions obtained using the geoacoustic parameters estimated from the inversion process for the surficial sediment layer and those corresponding to the mean grain size of $1.3{\phi}$ for lower layer are reasonably agreement with the measured bottom loss data.

Inversion toy Geometric and Geoacoustic Parameters in Matched-field Processing (정합장처리에서 유전자 알고리듬에 의한 기하와 지음향 매개변수 역산)

  • Shin Kee-Cheol;Park Jae-Eun;Kim Jea-Soo
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.339-343
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    • 2001
  • 본 연구에서는 수중 음의 전달에 작용하는 기하와 지음향 매개변수들을 전역 최적화(global optimization) 방법인 유전자 알고리듬을 사용하여 추정하려한다. 유전자 알고리듬은 목적함수가 불규칙적인 경우에도 모든 가능한 매개변수들을 조사하지 않으면서 전역 최대치 또는 최소치를 추정할 수 있는 최적화 방법으로, 정합장처리와 관련된 매개변수의 조사에 적합한 방향성 조사법이라 할 수 있다. 유전자 알고리듬을 이용하여 천해 해양환경에서 수치실험을 통해 매개변수 역산의 가능성을 살펴보도록 하였다.

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Underwater Acoustic Research Trends with Machine Learning: Ocean Parameter Inversion Applications

  • Yang, Haesang;Lee, Keunhwa;Choo, Youngmin;Kim, Kookhyun
    • Journal of Ocean Engineering and Technology
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    • v.34 no.5
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    • pp.371-376
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    • 2020
  • Underwater acoustics, which is the study of the phenomena related to sound waves in water, has been applied mainly in research on the use of sound navigation and range (SONAR) systems for communication, target detection, investigation of marine resources and environments, and noise measurement and analysis. Underwater acoustics is mainly applied in the field of remote sensing, wherein information on a target object is acquired indirectly from acoustic data. Presently, machine learning, which has recently been applied successfully in a variety of research fields, is being utilized extensively in remote sensing to obtain and extract information. In the earlier parts of this work, we examined the research trends involving the machine learning techniques and theories that are mainly used in underwater acoustics, as well as their applications in active/passive SONAR systems (Yang et al., 2020a; Yang et al., 2020b; Yang et al., 2020c). As a follow-up, this paper reviews machine learning applications for the inversion of ocean parameters such as sound speed profiles and sediment geoacoustic parameters.