Search Results (47)

This paper addresses the challenge of accurately measuring liquid level interfaces in multiphase mixed media by proposing a detection method based on ultrasonic transmission. First, a mathematical model of the ultrasonic measurement system was established, and the acoustic field characteristics of transducers with different frequencies and diameters in slurry were simulated and analyzed to determine the optimal excitation frequency and probe diameter. On this basis, an echo sound pressure calculation model based on the side-incidence method was constructed, and a formula for calculating the liquid level interface height was derived. Finally, an experimental test platform with a multi-layer steel container was built to measure the propagation velocity, attenuation coefficient, and acoustic impedance coefficient of ultrasound in the slurry, verifying the feasibility of the liquid level interface measurement method. Full article

Fabry–Perot resonator (FPR) sensors are widely implemented in optical and microwave waveguides because their interference fringe spectra enable highly sensitive, stable, and calibration-free measurements. In contrast, despite the extensive use of beams and plates as waveguides in vibration- and ultrasound-based structural health monitoring (SHM), an explicit FPR framework for these mechanical waveguides has not been established. This paper demonstrates that flexural beams can be rigorously treated as FPRs despite their inherently dispersive nature. Through analytical derivation, wave-propagation analysis, and fringe-based group-velocity extraction, we show that flexural-beam resonances arise from multi-reflection interference analogous to Fabry–Perot interference. A closed-form relationship between the frequency-dependent group velocity and the FPR free spectral range (FSR) is established, enabling inverse determination of mechanical or environmental perturbance from the FPR fringe spectrum. By extending FPR-based fringe analysis to dispersive mechanical waveguides, this work introduces a theoretical framework for implementing dispersive mechanical waveguide-based FPR sensors. Full article

Ultrasound propagation velocity was investigated as a non-destructive predictor of open porosity (${\rho }_0$) and water absorption ($A_w$) in volcanic rocks (two ignimbrites, a trachyte, and a basalt). Six velocity measurements were obtained under dry and saturated conditions along three orthogonal directions, and the dry Z-axis velocity was selected as the reference univariate predictor because it provided the highest explanatory power and the best cross-validated performance among the tested ultrasound variables. Four univariate regressions (linear, exponential, power law, and second-order polynomial), parametric multivariable linear regression, and five machine learning regressors were compared using lithology-stratified 5-fold cross-validation, grouping both ignimbrites as a single lithology. Univariate models showed moderate predictive capability for ${\rho }_0$ (cross-validated coefficient of determination $R^2\approx$ 0.506 to 0.580), whereas $A_w$ was captured more accurately, with the power law model reaching 0.923 ± 0.008. Multivariable linear regression improved ${\rho }_0$ when lithology was included (0.803 ± 0.084), while changes for $A_w$ were small. The highest accuracy was achieved by ensemble tree methods: extremely randomized trees with lithology yielded 0.949 ± 0.015 for ${\rho }_0$ (root mean square error 2.16 ± 0.38 percentage points), and Gradient Boosting with lithology yielded 0.976 ± 0.006 for $A_w$ (0.80 ± 0.12 percentage points). Full article

Background/Objective: Activity of SGK-1 has been associated with mechanical aspects of vascular remodeling and matrix stiffening has been a known characteristic of AAA. We hypothesis that VSMC-specific SGK-1 activity is vital to growth of AAA and contributes to progressive aortic stiffness. Methods: C57Bl/6 and SMC-SGK-1KO^+/− mice underwent AAA induction vs Sham on day 0. A subset of C57Bl/6 mice had pump implantation to treat with EMD638683. Aortic ultrasound images were obtained on Day 0 and Day 21 and analyzed for mechanical parameters. At terminal procedure the infrarenal aorta was harvested for immunoblot analysis. Results: At Day 21, C57Bl/6+AAA mice showed growth of 72.27% ± 2.2% versus the C57Bl/6+Sham (p < 0.0001) with associated 3.71 ± 1.15-fold increase in SGK-1 activity (p = 0.001). C57Bl/6+AAA+EMD mice demonstrated growth of 23.68% ± 2.82% (p = 0.0452) with no significant change in SGK-1 activity. SMC-SGK1-KO^+/−+AAA mice had growth of 28.20% ± 3.74% compared to SMC-SGK1-KO^+/−+Sham (p = 0.004) with increased SGK-1 activity (p = 0.0303). Radial strain was significantly reduced in the C57Bl/6+AAA (p = 0.0062) and C57Bl/6+AAA+EMD (p = 0.0135) when compared to C57Bl/6+Sham. Distensibility was significantly reduced in C57Bl/6+AAA (p = 0.01). Pulse propagation velocity (PPV) was significantly elevated in C57Bl/6+AAA mice (p < 0.0001) but inhibited by EMD therapy (p = 0.0007 vs. C57Bl/6+AAA). SMC-SGK1-KO^+/− +AAA mice showed significant reductions in radial strain (p = 0.0011) and distensibility (p = 0.0233) with a modest, but significant, increase in PPV (p = 0.0148). Conclusions: SGK-1 inhibition attenuated AAA growth and preserved vascular function. Targeting this pathway may provide a directed medical therapy for AAA and warrants further investigation. Full article

As uniaxial compressive strength (UCS) of rock material is influenced by petrographic characteristics, special emphasis is given to the visual assessment and determination of rock properties. Visual determination of properties such as lithology, fabric, defects and porosity were conducted on six petrographically different limestone varieties from Istria, Croatia. In addition to the macroscopic and microscopical determination of petrographic characteristics, measurements of ultrasound propagation velocity through samples were also conducted. According to the gained results of visual macro and micro assessment and ultrasound propagation, velocity estimation of uniaxial compressive strength was performed. Using predicted values of UCS, classification of samples according to different classifications was conducted where four out of six varieties of limestone were classified correctly. Based on the achieved results, the method has proven successful for rocks, which have uniaxial compressive strength over 100 MPa. Full article

Distinguishing subcutaneous adipose tissue (SAT) from intermuscular adipose tissue (IMAT) is clinically important because IMAT infiltration is strongly associated with age-related functional decline, sarcopenia, diabetes, cardiovascular disease, and obesity. Current assessments rely on MRI or CT, which are stationary, costly, and labor-intensive. Portable ultrasound-based solutions could enable broader, proactive screening. This model study investigated the feasibility of differentially assessing SAT and IMAT using features extracted from propagating ultrasound signals. Twenty-five phantoms were constructed using gelatin as a muscle-mimicking matrix and oil as the SAT and IMAT compartments, arranged to provide gradual variations in fat fractions ranging from 0% to 50%. Ultrasound measurements were collected at 0.8 MHz and 2.2 MHz, and multiple evaluation criteria were computed, including ultrasound velocity and parameters derived from the signal intensity. Classification domains were then generated from intersecting decision rules associated with these criteria. In parallel, artificial neural networks (ANN/LSTM) were trained and tested on identical phantom subsets to evaluate data-driven classification performance. Both the rule-based and ANN/LSTM approaches achieved diagnostically meaningful separation of SAT and IMAT. The aim of this work was to perform an experimental proof-of-concept study on idealized tissue models to demonstrate that ultrasound measurements can reliably differentiate SAT and IMAT, supporting the development of future screening devices. Full article

The propagation of high-frequency ultrasound waves will generate both physical and chemical effects as they propagate through a liquid medium, such as acoustic streaming, an acoustic fountain, and atomization. These phenomena are believed to be the main factors that contribute to the enhancement of mass transfer in the gas–liquid carbon dioxide (CO₂) absorption system. Computational Fluid Dynamic (CFD) simulation is one of the powerful tools that can be used to model the complex hydrodynamic behavior induced by the propagation of ultrasound waves in the liquid medium. In this study, the ultrasonic irradiation forces were simulated via the momentum source term method using commercial CFD software (ANSYS Fluent V19.1). In addition, a parametric study was conducted to investigate the influences of absorber height and ultrasonic power on the hydrodynamic mixing performance. The simulation results indicated that enhanced mixing and a higher intensification factor were achieved with increased fountain flow velocity, particularly at the lowest absorber height and highest ultrasonic power. Conversely, the energy efficiency was improved with the increase of absorber height and decrease of ultrasonic power. To determine the optimal combination of absorber height and ultrasonic power, this trade-off between the energy efficiency and intensification in the ultrasonic-assisted absorption system (UAAS) is a crucial consideration during process scale-up. Full article

Ultrasonic signal processing methodologies use many signal parameters to be investigated, one of which is time-of-flight (ToF). There are many and various methods used to determine ToF, such as threshold detection, peak-based methods, cross-correlation, zero-crossing tracking algorithms, etc. The application of most of these methods becomes problematic when the background noise becomes high and the signal amplitude, frequency, or propagation velocity changes. In order to partially solve these problems, this paper proposes a new and simple method to determine the time-of-flight and center frequency of signals based on the use of zero-crossing times of filtered signals to calculate these parameters. Taking advantage of the idea that these zero-crossing times are concentrated around the maximum of the signal envelope, they were used as the time-of-flight of the signal. Together with the ToF, the center frequency of the signal was also determined. The proposed method was adapted to the processing of experimental signals obtained during various ultrasound investigations. By processing S₀ mode signals propagating in the sheet molding compound plate, the propagation velocity of this mode was calculated. Its value was compared with the value obtained by the 2D FFT method. The obtained results differed by 0.9%. Using simulated signals propagating in 1 mm-thick aluminum, the phase and group velocity segments of the A₀ mode were calculated. Their values differed by 0.7% from the theoretically calculated values of the dispersion curves by the SAFE method. Full article

The diversity of commercial tree planting sites, with their distinct environmental conditions, directly influences tree growth and consequently impacts the wood properties in various ways. However, there is limited research evaluating the impact of these variations in nondestructive testing. Therefore, this study aimed to investigate whether edaphoclimatic variations affect parameters obtained through nondestructive tests conducted on standing trees. To this end, 30 specimens were selected from 3 Eucalyptus sp. clones, aged 1, 3, and 4 years, grown in 2 regions, totaling 540 trees. Tree development was monitored quarterly over 12 months. The tests included ultrasound propagation, drilling resistance, and penetration resistance, and the trees were measured for diameter at breast height (DBH) and height. Among the edaphoclimatic factors evaluated, only temperature and soil water storage differed statistically between the two study regions. The higher temperature and lower soil water storage in region 2 promoted tree growth, with these trees showing greater drilling resistance and higher longitudinal wave velocities. In addition, the influence of climatic factors was evidenced by the variation of wave propagation velocity throughout the year. Periods of lower water availability resulted in higher velocities, while periods of greater precipitation were associated with lower velocities. The research results showed that temperature and soil water storage had significant effects on tree growth (DBH and height), as well as ultrasound wave propagation velocity and drilling resistance. Full article

Microwave-absorbing suspicious objects (MASOs) found using microwave-induced thermoacoustic imaging (MTI) can be divided into two types—endogenous (such as tumors or hematoceles) and exogenous (such as calculi or foreign bodies). These have different microwave absorption or ultrasonic velocity than normal human tissue, so MTI is efficient in detecting these anomalies. However, the existing MTI techniques can only reflect morphological information, making it difficult to distinguish the type of each anomaly. In this paper, a newly enhanced MTI system composed of a multiple-element ring transducer and a parallel data acquisition system (DAS) is presented. By using ultrasonic velocity and microwave absorption measurements, where the ultrasonic velocity is mainly used as an additional parameter to reflect mechanical characteristics, the type of the detected anomaly can be identified. In our experiments, the MASO can be located through the absorption difference detected by MTI. Due to the use of multiple-element transducers and a parallel DAS, the raw data can be acquired within about 20 ms for a two-dimensional image. Additionally, the ultrasonic velocity of the MASO can be calculated from the time sequence diagram of ultrasound propagation with a maximum time error of 0.084 μs. Apart from distinguishing the type of the anomaly, the proposed ultrasonic velocity-assisted microwave-induced thermoacoustic imaging (US-MTI) system has other advantages, such as being noninvasive, and allowing rapid imaging and a large field of view, which make US-MTI a suitable modality for regular screening. Full article

This work demonstrates the use of an ultrasonic methodology to monitor bubble density in a water column. A flow regime with droplet size distribution between 0.2 and 2 mm was studied. This range is of particular interest because it frequently appears in industrial flows. Ultrasound is typically used when the size of the bubbles is much larger than the wavelength (low frequency limit). In this study, the radius of the bubbles ranges between 0.6 and 6.8 times the wavelength, where wave propagation becomes a complex phenomenon, making existing analytical methods difficult to apply. Measurements in transmission–reception mode with ultrasonic transducers operating at frequencies of 2.25 and 5.0 MHz were carried out for different superficial velocities. The results showed that a time-averaging scheme is necessary and that wave parameters such as propagation velocity and the slope of the phase spectrum are related to the number of bubbles in the column. The proposed methodology has the potential for application in industrial environments. Full article

The influence of acoustic anisotropy on ultrasonic testing reliability poses a challenge in evaluating products from additive technologies (AT). This study investigates how elasticity constants of anisotropic materials affect defect signal amplitudes in AT products. Experimental measurements on AT samples were conducted to determine elasticity constants. Using Computational Modeling and Simulation Software (CIVA), simulations explored echo signal changes across ultrasound propagation directions. The parameters $A_{13}$ (the ratio between the velocities of ultrasonic transverse waves with vertical and horizontal polarizations at a 45-degree angle to the growth direction), $A_3$ (the ratio for waves at a 90-degree angle), and $A_g$ (the modulus of the difference between $A_{13}$ and $A_3$) were derived from wave velocity relationships and used to characterize acoustic anisotropy. Comparative analysis revealed a strong correlation (0.97) between the proposed anisotropy coefficient $A_g$ and the amplitude changes. Threshold values of $A_g$ were introduced to classify anisotropic materials based on observed amplitude changes in defect echo signals. In addition, a method leveraging deep learning to predict $A_g$ based on data from other anisotropy constants through genetic algorithm (GA)-optimized neural network (NN) architectures is proposed, offering an approach that can reduce the computational costs associated with calculating such constants. Full article

The measurement of musculoskeletal tissue properties and loading patterns during physical activity is important for understanding the adaptation mechanisms of tissues such as bone, tendon, and muscle tissues, particularly with injury and repair. Although the properties and loading of these connective tissues have been quantified using direct measurement techniques, these methods are highly invasive and often prevent or interfere with normal activity patterns. Indirect biomechanical methods, such as estimates based on electromyography, ultrasound, and inverse dynamics, are used more widely but are known to yield different parameter values than direct measurements. Through a series of literature searches of electronic databases, including Pubmed, Embase, Web of Science, and IEEE Explore, this paper reviews current methods used for the in vivo measurement of human musculoskeletal tissue and describes the operating principals, application, and emerging research findings gained from the use of quantitative transmission-mode ultrasound measurement techniques to non-invasively characterize human bone, tendon, and muscle properties at rest and during activities of daily living. In contrast to standard ultrasound imaging approaches, these techniques assess the interaction between ultrasound compression waves and connective tissues to provide quantifiable parameters associated with the structure, instantaneous elastic modulus, and density of tissues. By taking advantage of the physical relationship between the axial velocity of ultrasound compression waves and the instantaneous modulus of the propagation material, these techniques can also be used to estimate the in vivo loading environment of relatively superficial soft connective tissues during sports and activities of daily living. This paper highlights key findings from clinical studies in which quantitative transmission-mode ultrasound has been used to measure the properties and loading of bone, tendon, and muscle tissue during common physical activities in healthy and pathological populations. Full article

Orthotropic steel decks (OSDs) are commonly used in the construction of bridges due to their load-bearing capabilities. However, they are prone to fatigue damage over time due to the cyclic loads from vehicles. Therefore, the early structural health monitoring of fatigue damage in OSDs is crucial for ensuring bridge safety. Moreover, Lamb waves, as elastic waves propagating in OSD plate-like structures, are characterized by their long propagation distances and minimal attenuation. This paper introduces a method of emitting high-energy ultrasonic waves onto the OSD surface to capture the nonlinear Lamb waves formed, thereby calculating the nonlinear parameters. These parameters are then correlated with the fatigue damage endured, forming a damage index (DI) for monitoring the fatigue life of OSDs. Experimental results indicate that as fatigue damage increases, the nonlinear parameters exhibit a significant initial increase followed by a decrease. The behavior is distinct from the characteristic parameters of linear ultrasound (velocity and energy), which also exhibit changes but to a relatively smaller extent. The proposed DI and fatigue life based on nonlinear parameters can be fitted with a Gaussian curve, with the R-squared value of the fitting curve being close to 1. Additionally, this paper discusses the influence of rib welds within the OSDs on the DI, whereby as fatigue damage increases, it enlarges the value of the nonlinear parameters without altering their trend. The proposed method provides a more effective approach for monitoring early fatigue damage in OSDs. Full article

Piezoelectric materials, which exhibit a charge distribution across the surfaces in reaction to mechanical strain, find significant utility in actuation and sensing applications. Apart from actuation applications like acoustic devices, motors, and vibration damping, an emerging domain for ultrasonic actuators lies in additive manufacturing processes. Ultrasonic waves applied during solidification aim to modulate grain structure and minimize defects. This research focuses on a fixture designed to facilitate and optimize ultrasonic wave propagation through the build plate in laser powder bed fusion additive manufacturing by utilizing a piezoelectric transducer. Three implementations of piezoelectric transducers were evaluated based on their out-of-plane ultrasonic velocity transmissions. It was determined that a thin plate adhered to the surface of the piezoelectric transducer yielded the most favorable outcomes for implementation, achieving 100% transmission of velocity and energy. Preliminary analysis of melt pool morphology and defects in single-track laser scanning experiments demonstrated the impact of ultrasound on solidification, hinting at a novel approach to enhancing the printability of alloys in laser powder bed fusion additive manufacturing processes. The optimal fixture and the explored transducing efficiency could further guide advanced ultrasound testing to enable in situ defect and texture detection during the additive manufacturing processes. Full article