Near-field target strength of finite cylindrical shell in water

Lee, Keunhwa; Choo, Yeon-Seong; Choi, Giyung; Choo, Youngmin; Byun, Sung‒Hoon; Kim, Kookhyun

doi:10.1016/j.apacoust.2021.108233

Cited by 3 publications

(2 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An experiment for target scattering was conducted in a water tank with size of 35 m (length) × 20 m (width) × 9 m (depth). A simple illustration of the water tank is shown in Figure 7 a, and its details are provided comprehensively in [ 27 ]. A 1 s long linear frequency-modulated pulse signal with a bandwidth between 0.5 and 25 kHz from a transducer impinged on the cylindrical shell target, and the scattered signal from the target was measured using two hydrophones at different water depths (referred to as R1 and R2).…”

Section: Application Of Ga-hmm To Measured Acoustic Datamentioning

confidence: 99%

“…On the other hand, the first elastic wave (approximately 0.6 ms) was immediately behind the specular echo and exhibited a small amplitude in the R2 measurement. The arrival times were confirmed by comparing the measured data with the simulated data based on the same environment [ 27 ]. The second elastic waves in the R1 and R2 measurements arrived at approximately 1.3 and 1.5 ms, respectively.…”

Section: Application Of Ga-hmm To Measured Acoustic Datamentioning

confidence: 99%

See 1 more Smart Citation

Underwater Acoustic Signal Detection Using Calibrated Hidden Markov Model with Multiple Measurements

You

Byun

Choo

2022

Sensors

Self Cite

View full text Add to dashboard Cite

It is important to find signals of interest (SOIs) when operating sonar systems. A threshold-based method is generally used for SOI detection. However, it induces a high false alarm rate at a low signal-to-noise ratio. On the other side, machine-learning-based detection is performed to obtain more reliable detection results using abundant training data, costing intensive time and labor. We propose a method with favorable detection performance by using a hidden Markov model (HMM) for sequential acoustic data, which requires no separate training data. Since the detection results from HMM are significantly affected by the random initial parameters of HMM, the genetic algorithm (GA) is adopted to reduce the sensitivity of the initial parameters. The tuned initial parameters from GA are used as a start point for the subsequent Baum–Welch algorithm updating the HMM parameters. Furthermore, multiple measurements from arrays are exploited both in determining the proper initial parameters with GA and updating the parameters with the Baum–Welch algorithm. In contrast to the standard random selection of the initial point with single measurement, a stable initial point setting by the GA ensures improved SOI detections with the Baum–Welch algorithm using the multiple measurements, which are demonstrated in passive and active acoustic data. Particularly, the proposed method shows the most confidential detection in finding weak elastic surface waves from target, compared to existing methods such as conventional HMM.

show abstract

Section: Application Of Ga-hmm To Measured Acoustic Datamentioning

confidence: 99%

Section: Application Of Ga-hmm To Measured Acoustic Datamentioning

confidence: 99%

Underwater Acoustic Signal Detection Using Calibrated Hidden Markov Model with Multiple Measurements

You

Byun

Choo

2022

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

Theoretical investigation on the underwater sound absorption of a functionally graded anechoic coating under the phased arc array incidence

Dong

Zhou

Chen

et al. 2023

Applied Mathematical Modelling

View full text Add to dashboard Cite

Ray-Based Analysis of Subcritical Scattering from Buried Target

Choo

Choi

Lee

et al. 2023

JMSE

View full text Add to dashboard Cite

A ray approach is used to simulate subcritical scattering from a buried target at low-to-high frequencies (100 Hz–15 kHz). A penetrating wave at a subcritical angle decays along the depth at the bottom (i.e., evanescent wave) and propagates horizontally at a subcritical angle-dependent speed lower than the sound speed of the bottom. The corresponding target strength (TS) is distinguished from that of a standard plane wave. Its pattern is asymmetric by the evanescent wave including for symmetric targets and is more complicated owing to the higher wavenumber induced by the lower speed of the evanescent wave. A scattered signal is simulated by considering the features of the penetrating wave with the TS and then verified using the finite element method. In the ray approach, once the TS is computed, a scattered field is efficiently derived with low computational complexity. Strong peaks are observed in the scattered signal via mid-frequency enhancement; however, their amplitudes are less than those yielded by the free-field target owing to the more diminished penetrating waves at higher frequencies. The peaks indicate the possibility of detecting the buried target using a receiver near the target (bistatic sonar) with a broadband source signal that includes low-to-mid frequencies.

show abstract

Near-field target strength of finite cylindrical shell in water

Cited by 3 publications

References 24 publications

Underwater Acoustic Signal Detection Using Calibrated Hidden Markov Model with Multiple Measurements

Underwater Acoustic Signal Detection Using Calibrated Hidden Markov Model with Multiple Measurements

Theoretical investigation on the underwater sound absorption of a functionally graded anechoic coating under the phased arc array incidence

Ray-Based Analysis of Subcritical Scattering from Buried Target

Contact Info

Product

Resources

About