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Proceedings ArticleDOI

Quantification of frequency-dependent absorption phenomena

03 Oct 2019-Vol. 38, Iss: 1, pp 055002
TL;DR: In this paper, a method to quantify absorption and dissipation phenomena with arbitrary frequency dependence is presented using the raw moments of the signals from acoustic transmission measurements, and the method is applied to signals generated using acoustic field simulation with different absorption models.
Abstract: Of all fluid and solid properties, quantities that describe losses are among the most challenging to quantify. In part, this is due to superimposed dissipative mechanisms, such as diffraction effects from spatially limited sources. Inherent to all these phenomena, however, is a specific frequency dependence. The nature of the frequency dependence varies, resulting from the respective absorption mechanism. Pure fluids, for example, exhibit absorption of acoustic waves with quadratic frequency dependence[1]. In solids, there are several absorption models that can be applied, each having different characteristics with respect to frequency. Other dissipative effects, such as diffraction, also show frequency dependence. In an approach using the raw moments of the signals from acoustic transmission measurements, a method to quantify absorption and dissipation phenomena with arbitrary frequency dependence is presented. The described method is applied to different absorption measurement problems. To verify that accurate results can be achieved under ideal conditions, the method is applied to signals generated using acoustic field simulation with different absorption models. To show its numerical stability, it is used qualitatively to evaluate the absorption of a fluid at different thermodynamic states.
Citations
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DOI
07 Oct 2021
TL;DR: In this article, the results obtained by two attenuation estimation algorithms, the Method-of-Moments and the Spectral-log-Difference method operating on k-wave-simulated ultrasonic B-mode volume data, were compared.
Abstract: According to the American Cancer Society, breast cancer is the second most common form of cancer in american women after skin cancer and the second major cause of cancer-related death after lung cancer. Still mammography is the imaging option guaranteeing the best diagnostic sensitivity but it causes high cost, is subjecting women to ionizing radiation, and is not readily available and not advisable to screen women on a very dense regular basis. Ultrasonic imaging, however is readily available in any gynecologist's clinic but still lags behind in sensitivity. Ultrasonic attenuation imaging, an imaging modality providing information on the local absorption property of the propagation medium, the various breast tissues, can help the clinician in her diagnosis by providing a color-coded overlay over the morphology that can be imaged using standard B-mode. We discuss and compare the results obtained by two attenuation estimation algorithms, the Method-of-Moments and the Spectral-log-Difference method operating on k-wave-simulated ultrasonic B-mode volume data. We also elaborate on the numerical complexity and the cost in terms of processing power necessary for both algorithms. The results show comparable performance with the MoM resulting in a smaller processor load as compared to the SLD technique.

2 citations

Journal ArticleDOI
TL;DR: In this paper, a measurement procedure using a modified two-chamber pulse-echo experimental setup is presented, enabling acoustic absorption and bulk viscosity (volume viscoity) measurements in liquids up to high temperature and pressure.

1 citations

01 Jan 2020
TL;DR: In this paper, the authors describe several measures to reduce systematic measurement deviation by decreasing or compensating the effects of dissipative effects in the fluid, such as diffraction and unwanted transmission at acoustic reflectors or waveguide boundaries.
Abstract: Motivation One major issue in the realization of acoustic absorption measurement systems is the fact that the absorption caused by dissipative effects in the fluid, such as viscosity, is superimposed by other losses resulting from the sound propagation in the respective measurement system. Examples for these effects are the spreading of the acoustic signal caused by diffraction and unwanted transmission at acoustic reflectors or waveguide boundaries. Unwanted reflected signals from planar surfaces included in the measurement system for constructive reasons may also interfere with the measurement. In this contribution, we describe several measures, which aim to reduce systematic measurement deviation by decreasing or compensating the aforementioned effects.

Cites methods from "Quantification of frequency-depende..."

  • ...An algorithm developed by the authors enables the determination of the frequency-independent absorption parameter a directly from the acquired signal spectra [8]....

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Journal ArticleDOI
TL;DR: In this article , a detailed analysis of the quantitative Ultraschall(QUS)-analyse is presented, in which a variety of algorithms for quantification of Gewebeabsorption are evaluated.
Abstract: Zusammenfassung Ultraschall ist eine sich im Gewebe ausbreitende mechanische Welle, die von den lokal vorherrschenden akusto-mechanischen Gegebenheiten in ihrem Ausbreitungsverhalten beeinflusst wird. Durch geeignete Verarbeitung der rückgestreuten und vom Ultraschallwandler empfangenen Signale kann daher auf Gewebeparameter, wie lokal wirkende Kompressionsmodule, Massendichte, Schallgeschwindigkeit, den isotropen Streukoeffizienten, aber auch auf die lokal wirkende Gewebeabsorption rückgeschlossen werden. Eine Disziplin, die in den letzten Jahren vermehrt Aufmerksamkeit in den wissenschaftlichen Publikationen zur medizinischen Ultraschallbildgebung gefunden hat, ist die Quantitative Ultraschall(QUS)-Analyse. In diesem Beitrag analysieren wir verschiedene Algorithmen zur Schätzung der örtlich hochaufgelösten Gewebeabsorption. Denn es wurde gezeigt, dass die Bereitstellung von farbcodierten Overlays von Absorptionsparametern über die herkömmlichen B‑mode-Ultraschall-Bilder, die ausschließlich die Morphologie darstellen, die diagnostische Qualität wesentlich verbessern kann.
Journal ArticleDOI
TL;DR: In this article , the authors analyze different algorithms for estimation of high spatial resolution tissue absorption parameters, such as local bulk modulus, mass density, speed of sound, isotropic scattering coefficient, and also the locally acting tissue absorption.
Abstract: Abstract Ultrasound is a mechanical wave propagating in tissue which is influenced in its propagation behavior by the locally prevailing acousto-mechanical conditions. By suitable processing of the back-scattered signals received by the ultrasound transducer, tissue parameters such as local bulk modulus, mass density, speed of sound, isotropic scattering coefficient, and also the locally acting tissue absorption can be inferred. A discipline that has received increasing attention in the medical ultrasonic imaging discipline and its scientific publications in recent years is quantitative ultrasound (QUS) which tries to estimate with great accuracy these local acting tissue parameters. In this paper we analyze different algorithms for estimation of high spatial resolution tissue absorption parameters. On the one hand, there is a simple absorption estimator based on the evaluation of the quotient of the power density spectra calculated for different depth regions (spectral-log-difference estimator), which, however, assumes a linearly with frequency increasing absorption, this is contrasted with an estimator which also allows to estimate a polynomial increase of the absorption with frequency (method-of-moments estimator). Since a closed-form solution cannot be given for this, a maximum-likelihood estimator for which there is always an estimate that can be computed numerically efficiently is developed. The results, tissue attenuation, are presented as a color-coded overlay on conventional B-mode ultrasound images showing only morphology.
References
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Journal ArticleDOI
TL;DR: In this article, a method for estimating seismic attenuation based on frequency shift data is presented, which is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation.
Abstract: We present a method for estimating seismic attenuation based on frequency shift data. In most natural materials, seismic attenuation increases with frequency. The high-frequency components of the seismic signal are attenuated more rapidly than the low-frequency components as waves propagate. As a result, the centroid of the signal's spectrum experiences a downshift during propagation. Under the assumption of a frequency-independent Q model, this downshift is proportional to a path integral through the attenuation distribution and can be used as observed data to reconstruct the attenuation distribution tomographically. The frequency shift method is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation. In comparison to some other methods of estimating attenuation, our frequency shift method is relatively insensitive to geometric spreading, reflection and transmission effects, source and receiver coupling and radiation patterns, and instrument responses. Tests of crosswell attenuation tomography on 1-D and 2-D geological structures are presented.

581 citations

Journal ArticleDOI
TL;DR: Van Wijngaarden's equation (VWE) for sound propagating through a bubbly liquid; Stokes' equation for acoustic waves in a viscous fluid; and the time-dependent diffusion equation (TDDE) for waves in the interstitial gas in a porous solid are examined.
Abstract: Acoustic wave propagation in a dispersive medium may be described by a wave equation containing one or more dissipation terms. Three such equations are examined in this article: van Wijngaarden’s equation (VWE) for sound propagating through a bubbly liquid; Stokes’ equation for acoustic waves in a viscous fluid; and the time-dependent diffusion equation (TDDE) for waves in the interstitial gas in a porous solid. The impulse-response solution for each of the three equations is developed and all are shown to be strictly causal, with no arrivals prior to the activation of the source. However, the VWE is nonphysical in that it predicts instantaneous arrivals, which are associated with infinitely fast, propagating Fourier components in the Green’s function. Stokes’ equation and the TDDE are well behaved in that they do not predict instantaneous arrivals. Two of the equations, the VWE and Stokes’ equation, satisfy the Kramers-Kronig dispersion relations, while the third, the TDDE, does not satisfy Kramers-Kronig, even though its impulse-response solution is causal and physically realizable. The Kramers-Kronig relations are predicated upon the (mathematical) existence of the complex compressibility, a condition which is not satisfied by the TDDE because the Fourier transform of the complex compressibility is not square-integrable.

18 citations

Journal ArticleDOI
TL;DR: An apparatus for the measurement of the speed of sound based on the pulse-echo technique is presented andspeed of sound data are presented with an uncertainty between 0.02% and 0.1%.
Abstract: An apparatus for the measurement of the speed of sound based on the pulse-echo technique is presented. It operates up to a temperature of 480 K and a pressure of 125 MPa. After referencing and validating the apparatus with water, it is applied to liquid ammonia between 230 and 410 K up to a pressure of 124 MPa. Speed of sound data are presented with an uncertainty between 0.02% and 0.1%.

17 citations

01 Jan 2017
TL;DR: In this paper, an analytic expression that links the decline of the spectral centroid (center frequency) of the acoustic signal to the medium's absorption coefficient has been derived by utilizing that acoustic waves experience dispersive effects in absorbing media.
Abstract: Next to the sound velocity, the absorption coefficient of acoustic waves in fluids is an important thermodynamic property. Although measurements of acoustic absorption have been conducted in the past, most of them negate the influence of parasitic dissipative effects or rely on either analytical or empirical compensation. A typical method for measuring acoustic absorption is to determine the decline of the acoustic signal amplitude as the wave propagates through the medium. We present an alternative approach, by utilizing that acoustic waves experience dispersive effects in absorbing media. It is known that acoustic absorption in fluids increases with the squared frequency of the acoustic wave. On this basis, we deduce an analytic expression that links the decline of the spectral centroid (center frequency) of the acoustic signal to the medium’s absorption coefficient. The results are verified using a simulation environment that is based on finite differences.

2 citations