Spatial Correlation Coefficient Images for Ultrasonic Detection

Cepel, Raina; Ho, K. C.; Rinker, Brett A.; Palmer, D. D.; Lerch, Terence P.; Neal, Steven P.

doi:10.1109/tuffc.2007.468

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…However, when Lamb waves propagate through the crack, not only will the amplitude change, but also the phase will shift or distort. The correlation coefficient of the received signal and the reference signal is calculated to extract the influence of the crack on the signals [22]. The rectangular window is used to intercept the received signals of Lamb wave, and the signal of defect-free position is used as reference signal.…”

Section: Experiments and Resultsmentioning

confidence: 99%

Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer for Air-Coupled Ultrasonic Applications

Wang

Lü

et al. 2016

Journal of Sensors

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The air-based 1-3 piezoelectric composite transducers are designed and fabricated in order to solve the acoustic impedance matching problem. Firstly, a finite element model using honeycomb structure as the piezoelectric composite matrix is built to reduce the acoustic impedance of the sensitive element. Three important factors, volume fraction of piezoelectric materialsφ, the thicknessh, and the sizesof the square cross section of piezoelectric column, are examined and verified in simulation. Then, according to the result of simulation, the piezoelectric composites and the air-coupled transducers are fabricated. The honeycomb structures of resin are produced by the method of 3D printing technology, with the volume fraction of air being 30%. The impedance characteristics and the excitation/reception performance of the air-coupled transducers are measured and optimized. Meanwhile, a scanning experiment is carried out to demonstrate the crack detection process in monocrystalline silicon.A0mode of Lamb waves is excited and collected. The location and size of the defect will be determined by calculating the correlation coefficients of the received signals and reference signals. Finally, a 15 mm × 0.5 mm × 0.5 mm scratch is clearly distinguished.

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Section: Experiments and Resultsmentioning

confidence: 99%

Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer for Air-Coupled Ultrasonic Applications

Wang

Lü

et al. 2016

Journal of Sensors

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“…The correlation coefficient (CC) is used to measure the quality of the extracted information data with respect to the original information data before embedding [31]. Specially, ultrasonic detection in medical images is based on amplitude for non-destructive evaluation [32]. In the correlation approach, each signal is correlated with its nearest neighbors for application of matched filtering.…”

Section: Simu La Tio N An D Mea Surement O F Qua Litymentioning

confidence: 99%

A Fresnelet-Based Encryption of Medical Images using Arnold Transform

Muhammad¹,

Kim²,

Bibi³

et al. 2013

IJACSA

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Abstract-Medical images are commonly stored in digital media and transmitted via Internet for certain uses. If a medical information image alters, this can lead to a wrong diagnosis which may create a serious health problem. Moreover, medical images in digital form can easily be modified by wiping off or adding small pieces of information intentionally for certain illegal purposes. Hence, the reliability of medical images is an important criterion in a hospital information system. In this paper, the Fresnelet transform is employed along with appropriate handling of the Arnold transform and the discrete cosine transform to provide secure distribution of medical images. This method presents a new data hiding system in which steganography and cryptography are used to prevent unauthorized data access. The experimental results exhibit high imperceptibility for embedded images and significant encryption of information images.

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“…The spatial correlations then have many potential applications including detecting multiple-scattering behavior, 9,10 evaluating material microstructure, 8,11 and testing for flaws within the volume of a part. [12][13][14] The key to applying spatial correlations of backscattering signals in practical scenarios is to assess their degree of similarity.…”

Section: Introductionmentioning

confidence: 99%

Higher-order spatial correlation coefficients of ultrasonic backscattering signals using partial cross-correlation analysis

Song

Kube

Zhang

et al. 2020

The Journal of the Acoustical Society of America

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The spatial correlation properties of ultrasonic backscattering signals in random media have important implications. For example, they can be used for microstructural characterization and flaw detection in engineering materials. However, the traditional spatial correlation coefficient (SCC) is only a leading order quantity that does not capture the true spatial correlations of random media. This is caused by neglecting confounding variables such as non-zero means or other non-zero odd-order moments. Here, the SCC is generalized from zeroth-to general-order through partial cross-correlation analysis. A series of indicators are defined to quantify the SCC curve at zero time lag, and the maximum time shift curve, which are both functions of lateral separation between two sensor positions. A stainless-steel specimen and a focused ultrasonic transducer are used to verify the method. Scattering measurements show that the higher-order SCC can consistently capture spatial correlations whereas the zeroth-order SCC is inadequate. The zeroth-order SCC is shown to predict a step size that can be more than six times too large. Thus, the present method can provide better understanding of statistical correlations and conditions to measure uncorrelated backscattering signals. V

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Spatial Correlation Coefficient Images for Ultrasonic Detection

Cited by 8 publications

References 12 publications

Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer for Air-Coupled Ultrasonic Applications

Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer for Air-Coupled Ultrasonic Applications

A Fresnelet-Based Encryption of Medical Images using Arnold Transform

Higher-order spatial correlation coefficients of ultrasonic backscattering signals using partial cross-correlation analysis

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