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Modulation of the refractive index in a medium by external stimuli enables fast and reversible control of light propagation. This technology for controlling light has led to new discoveries in a wide range of research fields from physics to life sciences and has played a major role in the development of photonics devices. In this article, we focus on ultrasound as an external stimulus and have devised a method to control the refractive index of a medium using ultrasound. Our research group has previously discovered that a giant refractive-index gradient (Δn on the order of 10−2) was induced when water was irradiated with high-frequency (100 MHz range), high-intensity (on the order of MPa) ultrasound. Here, we report ray-tracing simulations in a medium with a refractive-index gradient induced by ultrasonic radiation. A numerical model of the refractive-index gradient was developed based on the experimental data, and ray-tracing simulations were performed using the Euler–Lagrange equation. The ray-tracing simulation results were close numerically to the profiles of the laser beam observed in the experiment when the laser beam was incident on the refractive-index-gradient medium. [ABSTRACT FROM AUTHOR]

Detecting cracks of various sizes is crucial for monitoring and predicting rock failure. This study combines two acoustic methods—the passive acoustic emission (AE) and the active ultrasonic P-wave velocity to investigate the cracking process from initiation to propagation and coalescence of rocks containing pre-existing flaws, which simulate the intrinsic defects in natural rocks or rock masses, across different scales in three-dimensional space. The resultant AE activity is found sensitive to microcracks even in the early loading stage and can be divided into three stages: quiet, stable, and high growth periods. The positions of the microcracks can be obtained with the assistance of several AE sensors. It is also found that the P-wave velocity attenuation is more sensitive to macrocracks but less sensitive to microcracks. The results indicate that combining the AE and active ultrasonic-wave methods can provide comprehensive information to evaluate the damage levels and localize the internal cracks with multiple scales in the entire cracking process of rocks. The study also indicates the potential for predicting crack coalescence and failure based on the combination of these two nondestructive methods. In addition, the findings can also be applicable in the monitoring and prediction of failure in other brittle materials. [ABSTRACT FROM AUTHOR]

Microbubble-enhanced ultrasound provides a noninvasive physical method to locally overcome major obstacles to the accumulation of blood-borne therapeutics in the brain, posed by the blood-brain barrier (BBB). However, due to the highly nonlinear and coupled behavior of microbubble dynamics in brain vessels, the impact of microbubble resonant effects on BBB signaling and function remains undefined. Here, combined theoretical and prospective experimental investigations reveal that microbubble resonant effects in brain capillaries can control the enrichment of inflammatory pathways that are sensitive to wall shear stress and promote differential expression of a range of transcripts in the BBB, supporting the notion that microbubble dynamics exerted mechanical stress can be used to establish molecular, in addition to spatial, therapeutic windows to target brain diseases. Consistent with these findings, a robust increase in cytotoxic T-cell accumulation in brain tumors was observed, demonstrating the functional relevance and potential clinical significance of the observed immuno-mechano-biological responses.

Fouling in continuous reactors presents a significant challenge in the process intensification of specialty polymers. While in continuous stirred tank reactors (CSTRs) fouling is minimal, tubular reactors experience severe fouling, sometimes leading to complete blockage. Therefore, it is crucial to understand process and design conditions contributing to deposit formation. In this work, the impact of geometry, mixing elements, novel coatings, and ultrasonic waves are tested on tubular reactors for the polymerization of polyvinylpyrrolidone. [ABSTRACT FROM AUTHOR]

Three Dimensional Concrete printing (3DCP) stands at the forefront of modern construction methodologies, also named additive manufacturing, offering unparalleled time, cost, and labour savings compared to conventional approaches. The evaluation of fresh state parameters like extrudability and buildability through a specialised concrete extruder, combined with a methodical layer-by-layer deposition, ensures structural stability by precisely strengthening each layer. Mechanical strength evaluations highlight the printed material's anisotropic nature, revealing extreme reductions of Fy = 27.94%, Fx = 19.07%, and Fy = 16.33% in compression, flexural, and split tensile strengths, respectively, compared to cast specimens. This emphasises the importance of direction-specific mechanical testing in understanding material behaviour completely. Non-destructive testing (NDT) methods, like Ultrasonic Pulse Velocity (UPV) testing, are crucial for the qualitative assessment of the integrity and mechanical strength of concrete structures, including both printed and cast specimens, by establishing a strong correlation with compressive strength without causing any damage. Limited research indicates that the microstructure of the material plays a significant role in its mechanical strength, particularly in printed specimens. This claim is reinforced by mercury intrusion porosimetry (MIP) results, which reveal that printed specimens have slightly higher overall porosity, concentrated between 1 µm and 0.1 µm, while cast specimens show higher porosity in pores smaller than 0.1 µm. [ABSTRACT FROM AUTHOR]

Microstructural variability from manufacturing and post-fabrication activities have been attributed to a significant portion of failure in grade 91 steels. For example, heat treatment from welding can change the microstructure locally, which can change the hardness, phase content and grain size. This article explores the use of ultrasonic coda waves to detect microstructural changes in martensitic grade 91 steel. Tube samples with eight different microstructural conditions were simulated using different heat treatments and were tested using coda waves. Six different differential features were extracted from the coda wave signals. Only three features: Loss of correlation, differential curve length and coda wave interferometry showed accuracy > 50%. Further, clustered analysis to test the ability of the features to classify good, mid-level and bad microstructures showed that only loss of correlation had good accuracy. Overall, the study suggests that coda waves can be used to detect subtle changes in microstructure. [ABSTRACT FROM AUTHOR]

Defects can arise within the weld during the laser welding process of thin titanium sheets, and it is critical that these defects are detected. Shear horizontal (SH) waves offer good potential for defect detection, but require an understanding of how the ultrasonic waves interact with defects, in order to develop an optimised inspection setup, increasing the probability of defect detection. The geometry of a defect strongly affects the reflected signal magnitude, with finite element simulations showing that defect width and length determine the maximum SH0 wave reflection. Experiments confirm this behaviour. The defect width is shown to affect the reflection behaviour due to wave interference. Phase differences between the front face reflection and back face reflection cause a shift in the peak position. In addition, the experimental work presented in this paper also shows the potential for electromagnetic acoustic transducers to be used for the inspection of titanium components. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. This study developed a noninvasive targeted approach to modulate deep brain circuits involved in chronic pain and demonstrates rapid, substantial, and durable improvements in pain. Direct interventions into deep brain circuits constitute promising treatment modalities for chronic pain. Cingulotomy and deep brain stimulation targeting the anterior cingulate cortex have shown notable improvements in the unpleasantness of pain, but these interventions require brain surgeries. In this study, we have developed an approach that can modulate this deep brain affective hub entirely noninvasively, using low-intensity transcranial-focused ultrasound. Twenty patients with chronic pain received two 40-minute active or sham stimulation protocols and were monitored for one week in a randomized crossover trial. Sixty percent of subjects experienced a clinically meaningful reduction of pain on day 1 and on day 7 following the active stimulation, while sham stimulation provided such benefits only to 15% and 20% of subjects, respectively. On average, active stimulation reduced pain by 60.0% immediately following the intervention and by 43.0% and 33.0% on days 1 and 7 following the intervention. The corresponding sham levels were 14.4%, 12.3%, and 6.6%. The stimulation was well tolerated, and no adverse events were detected. Side effects were generally mild and resolved within 24 hours. Together, the direct, ultrasonic stimulation of the anterior cingulate cortex offers rapid, clinically meaningful, and durable improvements in pain severity. [ABSTRACT FROM AUTHOR]

An economical and environment-friendly protocol involving the use of ultrasonic vibrations was developed for the synthesis of a series of diaryl-4-thiazolidinones. The highlights of the developed approach are significant enhancement in the product yield, short reaction time, solvent-free, free of any toxic metal as a catalyst, cheaper synthetic methodological approach as well as non-formation of side-products. The developed approach is useful in terms of immense biological relevance of thiazolidines as well as the greener approach for cyclo-condensation of functionalized imines with thioglycolic acid. [ABSTRACT FROM AUTHOR]

Rapid freeze-thaw (F-T) tests were conducted to study the frost resistance of desert sand concrete (DSC) at different stress levels (SL), desert sand replacement rate (DSRR) and the number of F-T cycles. The impact of the SL, DSRR, and number of F-T cycles on the mass loss rate, ultrasonic wave velocity, and stress-strain curve of DSC was investigated through uniaxial compression tests. Scanning electron microscope (SEM) was used to examine the microstructure of DSC. The constitutive relationship was established considering the influence of the SL and number of F-T cycles. The results indicated that the frost resistance and uniaxial compressive mechanical properties of DSC could be effectively enhanced when desert sand was added at 40%. The peak strain initially decreased and then increased as the DSRR increased. In contrast, the peak stress first increased and reached a maximum value as the DSRR increasing to 40%, followed by a gradual decrease. The F-T cycles gradually deteriorated the macroscopic properties of DSC. The proposed constitutive model of DSC was established by combining the two classical models as the ascending and descending sections, respectively. The model prediction results matched well with the experimental results, which can provide a theoretical basis for the engineering application of DSC under F-T cycles and loading environments. [ABSTRACT FROM AUTHOR]

We consider the spherical piston problem in relativistic fluid dynamics. When the spherical piston expands at a constant speed, we show that the self-similar solution with a shock front exists under the relativistic principle that all velocities are bounded by the light speed. The equation of state is given by P= \sigma ^2 \rho, where \sigma, the sound speed, is a constant. It is an important model describing the evolution of stars. Also, we present the global existence of BV solutions for the relativistic Euler system given that the piston speed is perturbed around a constant in a finite time interval. The analysis is based on the modified Glimm scheme and the smallness assumption is required on the initial data. [ABSTRACT FROM AUTHOR]

The nanometer-sized pores within coal are the primary sites for CH4 adsorption and competitive adsorption with CO2. Reasonable modification of the nanopore structure to enhance CH4 desorption, diffusion rates, and CO2 competitive adsorption effects can enhance significantly coalbed methane (CBM) production. However, ultrasonic synchronous modification of multiple features of nanopores leads to complex and variable gas adsorption behaviors in coal. To reveal the effect of ultrasonic modification of coal nanopores on gas adsorption, pore measurement experiments and molecular simulation studies were conducted. The results showed that the volume ratio of diffusion pores to adsorption pores (V2/V1) decreased significantly after ultrasonic excitation. In the original coal sample, V2/V1 was 3.05, while in the coal sample after ultrasonic treatment, V2/V1 ranged from 0 to 2.54. With decrease in the proportion of the volume of diffusion pores, the proportion of CH4 migration from the pore walls of the adsorption pores increased continuously. The proportion of CH4 migration from the pore walls of the diffusion pores to the pore space of the diffusion pores decreased continuously. The results of gas–solid interaction energy calculation showed that ultrasonic treatment of coal decreases the V2/V1 ratio, leading to 7.1–23.3% increase in CO2 competitive adsorption effect. It also resulted in 4–49% improvement in competitive adsorption efficiency. Additionally, based on gas–solid interaction energy data, an adsorption capacity evaluation model for coal under different gas compositions and pore volume ratios was constructed. The findings can guide ultrasonic-enhanced CBM. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Transactions C: Aspects is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, ultrasound waves were successfully applied to the osmosis process of dried dragon fruit products. Additionally, this study was aimed at determining the suitable parameters for the process of drying dragon fruit peels. The parameters including the size of slices (2–5 cm), blanching time (10–25 min), ultrasonic time (10–25 min), ultrasonic temperature (45°C–60°C), ultrasonic power (100–250 W), and drying temperature (45°C–60°C) were fully investigated. The parameters including size of slices at 4 cm, blanching time of 20 min at 100°C, ultrasonic time of 15 minutes, ultrasonic temperature of 55°C, ultrasonic power of 100 W, and drying temperature of 55°C displayed the highest vitamin C (22.291 mg acid ascorbic/100 g), total polyphenol content (1096.948 mg GAE/100 g), reducing sugar (40.643 g/L), and total sugar (724.089 g/L). The obtained products were pink, soft, as well as harmonious between sweet and sour taste. This research contributes to diversifying products from dragon fruit in Vietnam. [ABSTRACT FROM AUTHOR]

Ultrasonic waves were used for synthesis of novel hydrazones, bishydrazones, pyrazoles, 1,2,4-triazole and 1,3,4-oxadiazole. The structural formulae of the synthesized compounds were elucidated in terms of elemental and spectroscopic analyses. All synthesized compounds were estimated by testing total antioxidant capacity, iron‐reducing power, the scavenging activity against ABTS and DPPH radicals in addition to testing anti‐diabetic, anti‐Alzheimer and anti‐arthritic activities. All compounds displayed good to potent bioactivity. Compounds 6, 10 exhibit the highest antioxidant and free radicals scavenging activities. Furthermore, compounds 6, 10 demonstrate the strongest inhibition of α‐amylase and α-glucosidase. Compound 12 exhibit strongest acetylcholinesterase inhibition among prepared compounds. However, compounds 18a,b, 19 show a significantly higher inhibition percentage for protein denaturation and proteinase. The most bioactive prepared compounds 6, 10 and 12 were investigated toward docking methodology against appropriate protein. [ABSTRACT FROM AUTHOR]

The global recognition of eco‐friendly products like plant‐based dyes is escalating, driven by their exceptional biological and Ayurvedic attributes. This study isolates colorants from mango turmeric (Curcuma aromatica) using ultrasonic irradiation, supplemented with bio‐mordants to enhance color retention. Through the utilization of Response Surface Methodology and Central Composite Design, a technique that was optimized was completed to maximize coloring variables using statistical analysis. Results from 32 experimental runs reveal that optimal color depth (K/S = 19.399) was achieved with ultrasonic‐treated silk fabric (20 min exposure) using 65 mL of irradiated aqueous extract (20 min) with a pH of 5, supplemented with 1.5 g/100 mL salt of sodium chloride, maintained the temperature 75°C for the 45 min. Precoloring treatment with acacia, pomegranate, and pistachio extracts at specified concentrations enhanced colorfastness. Postdyeing, alterations in the concentrations of these extracts led to further improvements in colorfastness. Notably, adding Al+3 and Fe+2 salts, alongside tannic acid, exhibited notable effects in both pre‐ and postdyeing stages. While the colorfastness properties of unmordated silk fabric was lower than mordanted dyed silk fabric. Irradiation with ultrasonic waves significantly boosted the amount of dye that could be extracted from rhizomes of mango turmeric. Moreover, the application of bio and synthetic mordants in a strategic manner led to colorfastness ratings on silk fabric that ranged from excellent to satisfactory. This research underscores ultrasonic technologies and bio‐mordants' efficacy in sustainable dyeing processes, offering insights for developing eco‐friendly textile coloration methods. [ABSTRACT FROM AUTHOR]

Research into particulate polymer composites is of significant interest due to their potential for enhancing material properties, such as strength, thermal stability, and conductivity while maintaining low weight and cost. Among the various techniques for preparing particle-based composites, ultrasonic wave stimulation is one of the principal laboratory-scale methods for enhancing the dispersion of the discontinuous phase. Nevertheless, there is a scarcity of empirical evidence to substantiate the impact of stimulating materials with natural sound frequencies within the acoustic spectrum, ranging from 20 Hz to 20 kHz, during their formation process. The present work investigates the effect of acoustic stimuli with frequencies of 56, 111, and 180 Hz on the properties of an acrylic-based polymer and its discontinuous carbon-based composites. The results indicated that the stimulus frequency affects the cure time of the studied systems, with a notable reduction of 31% and 21% in the cure times of the neat polymer and carbon-nanofiber-based composites, respectively, after applying a frequency of 180 Hz. Additionally, the higher stimulation frequencies reduced porosity in the samples, increased the degree of dispersion of the discontinuous phase, and altered the composite materials' thermal, optical, and electrical behavior. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of novel semicarbazones and their biological activities, including antimicrobial properties. The study focuses on the preparation of semicarbazones with improved biological activity, achieved through ultrasonic irradiation and a simple solvent system. The compounds showed promising antibacterial activities, particularly (E)-2-(1-(3-chloro-4-fluorophenyl)ethylidene)-N-(2-chlorophenyl)hydrazine-1-carboxamide (4e), which exhibited good activity against both Gram-positive and Gram-negative bacteria. Molecular docking studies provided insights into the compounds' binding interactions with DNA gyrase, suggesting potential for further research on antimicrobial compounds. [Extracted from the article]

Selenium (Se) is considered to be an essential trace element needed for all living organisms. The importance, deficiency, and toxic effects of Se mainly depend on its quantity and chemical nature. It has been observed that the inorganic versions of Se are more hazardous than the organic versions. This review is mainly focused on the application of different extraction methods used for Se extraction and determination such as microextraction, solid-phase extraction (SPE), and their modified modes in the last 12 years. The use of different dispersive medium (magnetic field, ultrasonic radiation, and vortex agitator) to enhance Se separation is also part of this review. The usage of environmentally friendly solvents such as supramolecular solvents, hydrophobic deep eutectic solvents (DESs), and ionic liquids (ILs) are also the focus of attention in this review. This review is also emphasized the application of advanced microextraction methods, particularly liquid-phase microextraction (LPME). The most recent advances in LPME extraction techniques for Se in various environmental samples, as well as their prospects, are reviewed. Additionally, a summary of cheap, simple, and accurate techniques that have not yet been used to determine small amounts of Se has been provided. [ABSTRACT FROM AUTHOR]

An ultrasonic Rayleigh wave detection method is proposed to determine the geometrical characteristics of subsurface small-scale fractures in concrete. A three-dimensional observation system, including an inclined wedge ultrasonic device, is used to obtain the Rayleigh wave wide-angle data to exhibit the azimuth-dependent scattered wave field. The anisotropic characteristics of Rayleigh wave transmission coefficient are used to determine the distribution range and dip angle of fractures. Fracture models in concrete with different dip angles are designed, and the dip angle is correlated with the degree of attenuation (transmission coefficient) anisotropy. The transmission coefficient characteristics are presented in a random observing system. A focusing approach can be adopted to distinguish the subsurface fracture and to verify the reliability and flexibility of the surface wave approach in practice. The tendencies of experimental results are consistent with patterns obtained from numerical simulation. The proposed method has important application prospects for the non-destructive testing of complex invisible fractures in concrete. [ABSTRACT FROM AUTHOR]

In the ultrasonic testing of the mechanical properties of ferromagnetic materials, the main excitation mechanism modes of ultrasonic waves are Lorentz force mechanism ultrasonic and magnetostriction mechanism ultrasonic. Lorentz force mechanism ultrasonic mainly detects the conductive characteristics of materials, while magnetostriction mechanism ultrasonic mainly detects the hysteresis characteristics of materials. However, conventional electromagnetic acoustic transducers (EMATs) cannot simultaneously characterise these two characteristics of ferromagnetic materials. In this study, we conclude from the finite element simulation that a quantitative lift-off distance (i.e. the distance between EMAT and the specimen) can change the main mechanism mode of the excited ultrasonic wave. Based on this conclusion, an electromagnet electromagnetic acoustic transducer with dual main excitation modes (DM-E-EMAT) is designed, which can realise the dual mode switching of the main Lorentz force mechanism and main magnetostriction mechanism by adding or removing hollow square gasket. The ultrasonic testing of ferromagnetic materials based on the two main mechanisms of DM-E-EMAT can simultaneously characterise the conductivity and magnetostriction properties of ferromagnetic materials, which enables the characterisations of two types of characteristic parameters with one transducer, improves the efficiency of electromagnetic ultrasonic non-destructive testing of the mechanical properties and reduces the detection errors of ferromagnetic material. [ABSTRACT FROM AUTHOR]

Phenolic compounds in jackfruit (Artocarpus heterophyllus Lam.) peel were extracted using novel sequential microwave-ultrasonic-assisted extraction (SMUAE) and a natural deep eutectic solvent (NADES). Choline chloride-lactic acid (ChCl-LA) was an optimal NADES. Optimal conditions of SMUprobeAE (SMUpAE) were 415 W microwave power, 124 s irradiation time, and 7 min ultrasonic time. Total phenolic content (TPC) of a crude extract (CJPE) under the optimum conditions was 53.16 ± 1.23 mg GAE/g DW. SMUbathAE (SMUbAE) could be used instead of SMUpAE to prevent the corrosion of the probe. The different sequences of applying ultrasonic wave and microwave did not differently influence TPC, antioxidant activity of CJPE, and microstructure of peel residues. LC-QTOF-MS/MS profiling of natural products in purified extracts (PJPE) was differently affected by ChCl-LA and 60% EtOH. Chlorogenic acid was the main phenolic compound in PJPE. Glycyrrhetinic acid was found for the first time in ChCl-LA-PJPE. Therefore, SMUbAE integrated with ChCl-LA was an alternative green technique for extraction of phenolic compounds. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aircraft icing is one of the critical factors for flight safety. Timely and accurate monitoring of in-flight ice accretion is essential for flight systems to take immediate and effective action to significantly improve the efficiency of subsequent de-icing processes and ensure flight safety. Since carbon fiber reinforced polymer (CFRP) are now widely used in the aviation industry, the study of ice accretion on the surfaces of CFRP with anisotropic properties is of great importance. In this work, a three-dimensional frequency domain finite element model for icing CFRP laminate is first established, via which the mechanism of mode conversion of ultrasonic guided waves (UGWs) at different ice layer thicknesses is quantitatively analyzed. Then, the time-domain finite element simulation was performed, from which the time–frequency domain spectrogram of the acquired UGW signal is obtained by short-time Fourier transform (STFT). The extracted frequency–time-of-flight (ToF) curve of the signal via STFT shows high agreement with the theoretical results, which confirms the influence of icing on UGW propagation. Finally, numerous experiments with bonded lead zirconate titanate wafers to excite and acquire UGWs are conducted with different ice layer thicknesses and lengths on CFRP. The extracted frequency–ToF curves of UGW signals are used as input to a two-layer feedforward artificial neural network (ANN) to accurately evaluate the length and thickness of the ice layer. The high reliability of this method with ANN is confirmed, which shows the potential of the proposed UGW-based method for quantitative monitoring of icing length and thickness on aircraft CFRP laminate. [ABSTRACT FROM AUTHOR]

The internal defects in rock masses can significantly impact the quality and safety of geotechnical projects. Mechanical waves, as a common nondestructive testing (NDT) method, can reflect the external and internal structures of rock or rock masses. Analyses on the reflected and transmitted waves enable nondestructive identification and assessment of potential defects within rocks. Previous studies mainly focused on the variation of single or limited wave features like main frequency, amplitude and energy between the intact and non‐intact samples. In fact, most information contained in the waveforms is neglected. Techniques of data mining can provide a powerful tool to reveal this information and therefore a more accurate determination of the internal structures. In this study, 995,412 NDT data from 14 types of granite and gypsum samples with different cross‐section shapes and different types of defects are recorded by an ultrasonic wave generation and collection system. This dataset can be used not only as the training data for defect classification in NDT but also as a good reference for conventional NDT analyses. Besides, time‐series data analysis is an opportunity and challenging issue, this dataset holds great potential for broader application in general time‐series classification analysis. [ABSTRACT FROM AUTHOR]

Persistent symptoms of lateral epicondylitis prompt patients to seek effective conservative treatment. The study aimed to determine the effects of focused shock wave (FSWT) and ultrasound therapies for lateral epicondylitis. Sixty patients with tennis elbow were randomly divided into three equal groups: A, B, and C. Group A received a total of 3 FSWT sessions, with 7 days between treatments; Group B received ultrasound therapy in 10 sessions over 2 weeks, while patients in Group C were treated with placebo ultrasound. All patients were also given deep friction massage. Before the start of therapy, and at 1, 3, 6, and 12 weeks after its completion, pain intensity and function of the affected upper limb were assessed in all patients. Wrist extensor and flexor strength and grip strength were measured in the affected and unaffected limb. Significant reductions in pain and significant improvements in the function of the affected limb compared to baseline values were observed in all study groups at 6 and 12 weeks after the completion of therapy. Analysis of percentage changes in these variables showed significant differences between Groups A and B in favor of Group A. The strength of wrist extensors and grip strength of the affected limb at 6 and 12 weeks after treatment completion was significantly higher in Groups A and B compared to pre-therapy values. However, there were no statistically significant differences between the groups regarding percentage changes in muscle strength in the affected limb. Pain reduction and function improvement in patients with lateral epicondylitis were significantly greater after FSWT (0.2 mJ/mm2 / 4 Hz / 2000 shocks) than after sonotherapy (3 MHz / 0.5 W/cm2 / 20%). Increases in wrist extensor strength and grip strength of the affected limb were comparable after both therapies. Given the greater therapeutic effect in the subjective evaluation, we recommend a combination therapy of FSWT with deep friction massage. Trial registration The trial was prospectively registered in the ISRCTN registry (no. ISRCTN11907358 registration date 30.07.2020). [ABSTRACT FROM AUTHOR]

The Probabilistic Multistage (PM) algorithm was developed by authors for identifying and localizing damages in isotropic plates. More specifically, PM algorithm consists of a fully automated probabilistic damage imaging methodology based on ultrasonic guided wave propagation and a 5-sensor array working in a pitch-catch approach. The algorithm processes the gathered data in three steps to identify key features associated with damage. The aim of this work is to assess the effectiveness of the PM algorithm on more complex structures. Specifically, the study investigates three cases of study, made of Carbon Fiber Reinforced Plastic (CFRP) composite, characterized by different geometries and layups. The algorithm is initially tested on panels with artificial damage in the form of a Teflon disk located in a specific location between the middle laminae of the panels, which is used to replicate the effect of delamination. In order to expand the experimental dataset without incurring additional costs or waste, new damage conditions are simulated by adding masses on the upper surface of the panels. Each plate is investigated considering three different damage sizes and 16 different damage locations. The proposed algorithm successfully detects damages both within and outside the sensor network. The PM algorithm produces a clear damage positioning map and a positioning (probabilistic field) range for the identified damage. This information can be used to assist operators in conducting inspections more efficiently by focusing on the highlighted areas, which may potentially lead to reduced maintenance and repair expenses. [ABSTRACT FROM AUTHOR]

Compared to many conventional manufacturing methods, Additive Manufacturing/3D Printing (AM/3DP) techniques can produce highly optimized builds with unparalleled structural complexities, material combinations, and both internal and external geometrical intricacies, offering new degrees of freedom for optimization. However, unforeseen deviations in process parameters (e.g., laser beam scan speeds and power), material properties (e.g., powder morphology, alloy composition, mechanical and thermal properties), and machine health can lead to micro/macro-scale defects and quality concerns in the resulting builds and end-products. To address these concerns, it is crucial to assess quality and implement effective closed-loop control by understanding the sensitivity of quality attributes to perturbations and variations in process parameters, material properties, and machine health state. AM print speeds influence the material's microstructure, affecting its elastic properties, defect states, and, consequently, spectral resonance behavior. Here, a quality monitoring framework is introduced based on specially designed Phononic Crystal Artifacts (PCAs) printed alongside the actual build. Compared to the actual build, a PCA is a substantially smaller construct with a repeating pattern (periodic) internal structure to effectively capture and measure the build's defect state and mechanical and geometric complexities for quality assessment. In this study, we investigate the impact of varying print speeds in AM on the resonance frequencies of PCAs, which are related to mechanical properties and defects. Stainless steel 316L powder, widely used in powder-based AM/3DP, was chosen to print the Metal Phononic Crystal Artifacts (mPCAs). Our findings indicate that varying print speeds significantly influence ultrasonic waves' resonance and modal frequencies in the printed artifacts. Specifically, high print speeds resulted in measurable shifts in these frequencies, demonstrating the potential for real-time quality monitoring and process optimization in AM/3DP. The PCA approach offers real-time, non-destructive quality monitoring by using smaller, sensitive constructs to capture essential mechanical and geometric complexities, allowing for dynamic adjustment of print speeds and enhancing overall build precision and reliability in AM/3DP. [ABSTRACT FROM AUTHOR]

The surface residual stress of the parts has an important influence on their performance. The generation mechanism of surface residual stress in ultrasonic vibration-assisted grinding (UVAG) of bearing steel was investigated, and the correlation between processing parameters and residual stresses was obtained. Based on the ultrasonic vibration-assisted grinding force and thermal model and the flow stress model considering the initial material microstructure, the mechanical and thermal stresses of the material were calculated. Finally, the theoretical model of residual stress is established based on the yield theory and experimentally verified. High-speed ultrasonic aerostatic spindle for ultrasonic vibration-assisted grinding, change the inlet pressure to realize the ultrasonic amplitude and frequency adjustment, the experimental results show that the cutting direction and the vertical cutting direction of the residual stress test results and the model prediction results of the average relative error of 11.4% and 11.7%, and the rule of change is more consistent. Based on the experimental results, the influence pattern of process parameters on the experimental results was analyzed. The results show that the residual compressive stress on the surface of ultrasonic vibration-assisted grinding is directly proportional to the grinding depth, feed rate, and inlet pressure of pneumatic ultrasonic wave and inversely proportional to the linear speed of the grinding wheel. This study provides a theoretical basis for the analysis of UVAG residual stress and optimization of UVAG process parameters. [ABSTRACT FROM AUTHOR]

Most reported research for monitoring health of pipelines using ultrasonic guided waves (GW) typically utilize bulky piezoelectric transducer rings and laboratory-grade ultrasonic non-destructive testing (NDT) equipment. Consequently, the translation of these approaches from laboratory settings to field-deployable systems for real-time structural health monitoring (SHM) becomes challenging. In this work, we present an innovative algorithm for damage identification and localization in pipes, implemented on a compact FPGA-based smart GW-SHM system. The custom-designed board, featuring a Xilinx Artix-7 FPGA and front-end electronics, is capable of actuating the PZT thickness shear mode transducers, data acquisition and recording from PZT sensors and generating a damage index (DI) map for localizing the damage on the structure. The algorithm is a variation of the common source method adapted for cylindrical geometry. The utility of the algorithm is demonstrated for detection and localization of defects such as notch and mass loading on a steel pipe, through extensive finite element (FE) method simulations. Experimental results obtained using a C-clamp for applying mass loading on the pipe show good agreement with the FE simulations. The localization error values for experimental data analysed using C code on a processor implemented on the FPGA are consistent with algorithm results generated on a computer running Python code. The system presented in this study is suitable for a wide range of GW-SHM applications, especially in cost-sensitive scenarios that benefit from on-node signal processing over cloud-based solutions. [ABSTRACT FROM AUTHOR]

Neuromuscular deficits affecting functional ability can occur in patients with Achilles tendinopathy during difficult balance activities. This study aimed to assess postural control in patients with Achilles tendinopathy after shockwave and sonotherapy, using advanced analytical methods, including rambling-trembling signal decomposition and sample entropy. What are the differences in postural control between patients with Achilles tendinopathy after shockwave therapy, ultrasound therapy, and placebo ultrasound? Thirty-nine patients were included in the study, and randomly assigned to 3 groups, i.e., shockwave therapy, ultrasound therapy and placebo ultrasound. Postural sway was assessed during quiet standing with eyes open and closed, with two force platforms, one for the affected and the other for the non-affected limb, at baseline and at weeks 1 and 6 after treatment. Rambling-trembling trajectories and sample entropy were calculated for the antero-posterior and medio-lateral directions. The parameters of trembling trajectory in both directions were significantly smaller for the affected compared to non-affected limb. The ultrasound group had significantly larger rambling-trembling trajectories in the antero-posterior and medio-lateral sway directions than the shockwave therapy group. Also, all patients had more difficulty controlling their postural sway while standing with eyes closed compared to eyes open. Sample entropy was not significantly affected by the therapy type, timepoint and limb condition. As opposed to sample entropy, rambling-trembling decomposition can complement or replace traditional linear measures of COP time series in functional assessment of the Achilles tendon. • Patients with Achilles tendinopathy have altered postural control. • Trembling trajectory is smaller for the affected compared to non-affected limb. • Rambling-trembling method may contribute to the assessment of the Achilles tendon. [ABSTRACT FROM AUTHOR]

Lamb waves have become a focal point in ultrasonic testing owing to their potential for long-range and inaccessible detection. However, accurately estimating the flaws in plates using Lamb waves remains challenging because of scattering, mode conversion, and dispersion effects. Recent advances in laser ultrasonic wave techniques have introduced innovative visualization methods that exploit the dispersion effect of Lamb waves to visualize defects via, for example, acoustic wavenumber spectroscopy. In this study, we developed an interdigital transducer (IDT)-based scanning laser Doppler vibrometer (SLDV) system without a power amplifier using a low-power IDT fabricated from lead magnesium niobate–lead zirconate titanate single crystals. To validate the proposed low-power IDT-based SLDV, four different defective plates were measured for defects. A comparison between a conventional IDT-based SLDV, a dry-coupled IDT-based SLDV, and the proposed method demonstrated that the latter is highly reliable for measuring thin plate defects. [ABSTRACT FROM AUTHOR]

Accurate corrosion assessment plays an important role in ensuring structural safety of reinforced concrete (RC) structures. However, on‐site assessment of existing concrete structures presents many challenges, including high costs, limited inspection timeframes, and difficult accessibility. To facilitate inspection‐based corrosion assessment, this paper presents a novel approach by combining short‐term acoustic emission (AE) monitoring with selective crack width measurements for corrosion level (CL) assessment. AE sensing is a monitoring technique which can detect ongoing internal degradation mechanisms by analyzing ultrasonic waves emitted by the damage process. Yet, two major challenges arise on site: (1) practical limitations prevent continuous AE monitoring over the structure's entire lifetime and (2) AE can only generate relative results in the absence of reference measurements. This paper addresses both challenges to bridge the gap between laboratory experiments and on‐site monitoring of corroding RC structures. First, short periods of AE monitoring data are analyzed to investigate the potential of AE sensing over limited timeframes. Second, AE data of corroding RC beams are combined with sparse crack width measurements in order to obtain absolute CLs. The proposed methodology is experimentally validated by corroding eight beams with varying dimensions, corrosion zones, and reinforcement layouts. The experimental results prove that the estimated CLs closely match the rebar mass losses, with a mean absolute error of 1.53% CL for beams reaching up to 14% CL, confirming the potential of the combined AE and crack width measurement technique as an efficient and accurate condition assessment approach. Moreover, AE sensing provides detailed spatial variability of the rebar corrosion in the monitored zone, which is challenging to obtain with conventional techniques. By using this dual‐technique approach, shorter monitoring periods prove nearly as effective as continuous AE monitoring in accurately estimating CLs. [ABSTRACT FROM AUTHOR]

Simulations with the Saturn Thermosphere‐Ionosphere General Circulation Model have revealed global‐scale gravity waves in Saturn's upper atmosphere that have not been observed or predicted before. They are forced by diurnally varying zonally non‐uniform distributions of Joule heating and ion drag at the high‐latitude auroral regions in both hemispheres and propagate outward from the source region. The supersonic zonal phase speed imposed by Saturn's rotation and the subsonic meridional phase velocity of about 800 m s−1 ${\mathrm{s}}^{-1}$ form a distinct spiral wave structure. They exhibit features of gravity waves: vertical phase progression opposite to the propagation of wave energy and long vertical wavelengths consistent with the dispersion relation for gravity waves. The amplitudes of the perturbations grow with height, reaching 6%–10% for relative temperature variations and up to 350 m s−1 ${\mathrm{s}}^{-1}$ for the meridional velocity perturbations. The main effect of these waves is to accelerate the retrograde westerly jets. Plain Language Summary: Gravity waves are common in all convectively stable atmospheres. They are caused by a variety of sources and have horizontal extents ranging from a few kilometers to scales comparable to the radius of the planet. In simulations of the Saturnian upper atmosphere, we found a new form of gravity wave that has not been observed or predicted before. The waves are excited at 900–1,000 km above the 1 bar pressure level near the auroral ovals in both hemispheres. They are caused by the changing heating and drag in the auroral regions as Saturn rotates throughout the day. Saturn's large size and fast rotation make the waves move around the planet faster than the speed of sound in Saturn's atmosphere. They spread out from their source, creating a spiral pattern that covers a large part of the planet. We studied these waves and how they affect the global circulation. Unlike gravity waves on Earth and similar planets, which mostly slow down the surrounding winds, these waves in Saturn's upper atmosphere mainly speed up the strong westward jets. Key Points: General circulation modeling reveals large‐scale gravity waves in the upper atmosphere of Saturn that have never been reported beforeWaves are forced by Joule heating and ion drag at high‐latitude auroral regions, propagate outward and form a global spiral structureThe net dynamical effect of these zonally supersonic and meridionally subsonic waves is to accelerate the westward retrograde jets [ABSTRACT FROM AUTHOR]

A multi-frequency instantaneous wavenumber damage imaging method based on ultrasonic guided waves induced by laser point-by-point excitation is proposed in this paper. The experiment involved using the Nd:YAG pulsed laser is used as the excitation source to excite ultrasonic guided waves point-by-point in the detection area, and the piezoelectric ceramic transducer is used to receive ultrasonic guided wavefield at a fixed position. The wavefield information at different frequencies is extracted by a three-dimensional Fourier transform. The spatial phase distribution of the extracted guided wavefield with different frequencies is obtained by the Hilbert transform and phase unwrapping method. Then, the wavenumber of each detection point and the dispersion relations of the test piece with different thicknesses are calculated. Based on the calculated dispersion relation, the mapping relationship between the wavenumber and the thickness of the test piece is obtained. Furthermore, based on the obtained wavenumber information and wavenumber thickness mapping relationship, the thickness reduction depth of the defect can be calculated. Finally, the quantitative detection of defects is achieved through data fusion. The proposed method is verified through quantitative detection of the rectangular groove defects and the flat bottom defects with variable thickness and complex contour in the aluminium plate. At the same time, the detection results of the proposed method are compared with those of the single-frequency instantaneous wavenumber imaging method, single-frequency local wavenumber imaging method, and multi-frequency local wavenumber imaging method. In the detection results, the method proposed in this paper presents a better defect detection effect. [ABSTRACT FROM AUTHOR]

Ferrohydrodynamic pumps, with their compact design, offer a practical and efficient alternative to traditional pneumatic or mechanical pumps for driving microfluidic channels and fluidic devices, eliminating mechanical vibrations. A novel self‐circulating ferrohydrodynamic system has been developed to remotely control fluid flow within a linear acoustic cavity using a laser‐induced photothermal temperature gradient. This system enables the modulation of fluid flow rates in compact channels through adjustments in a D.C. magnetic field or laser‐induced surface temperature changes. Notably, laser intensity can accelerate, decelerate, or reverse flow rates within the channel, influencing ultrasonic waves propagating through fluidic cavities designed to resonate between 500 kHz and 700 kHz. The dynamic nature of the magnetoactive fluid cavity enhances wave‐matter interactions, particularly in acoustic domains. Laser‐induced flow control allows for precise manipulation of ultrasonic wave characteristics such as frequency, amplitude, mode splitting, phase shifting, and unidirectional transmission. This capability also supports the optical regulation of acoustic energy flow rates by halting or reversing fluid motion within the cavity. These advancements hold significant potential for applications in cavity acoustodynamics and underwater signal processing, promising innovations in remote fluidic control and acoustic modulation technologies. [ABSTRACT FROM AUTHOR]

To enhance the color quality and antioxidant potential of vacuum-freeze-dried strawberry tablets, ultrasonic waves were used as a freezing pretreatment. Results revealed that the * values of freeze − dried strawberries following ultrasonic pretreatment improved significantly by ∼60% and the C* values increased by 34.36%–51.65%. These findings suggest that ultrasonic pretreatment results in a brighter coloration of the strawberry samples. The ultrasound − assisted freezing treatment groups exhibited a significantly higher free radical scavenging ability compared with the nonultrasonic treatment group. This enhancement was attributed to the ultrasonic pretreatment, which increased the concentrations of total phenolic compounds, flavonoids, and anthocyanins, and effectively inhibited the activities of polyphenol oxidase and peroxidase, thereby reducing the content of red pigment in the strawberry samples. Furthermore, confocal laser scanning microscopy revealed a uniform distribution of sugar within the samples following ultrasonic treatment. Cluster analysis indicated that the primary indices influencing the color of the samples were total phenolic content and peroxidase activity. Therefore, the ultrasonic pretreatment method effectively enhances product color, inhibits enzyme activity, and increases anthocyanin content. This technology holds promising development prospects. [ABSTRACT FROM AUTHOR]

Ultrasonic non-destructive evaluation of concrete submerged in water is a complex phenomenon that has important implications for the durability and safety of marine structures such as bridges, piers and offshore platforms. The scattering of ultrasonic waves inside concrete materials with aggregate size comparable to the ultrasound wavelength often limits the interpretation of inspection results. To enhance the understanding of ultrasonic wave propagation inside the underwater concrete, numerical simulations using the finite element method (FEM) with the Transient Acoustics-Piezoelectric Interaction application mode of Multiphysics software package have been developed. This study focuses on developing a 2D numerical model to reproduce and illustrate the propagation of ultrasound in seven types of underwater concrete test blocks with various types of inclusions and voids embedded inside it. The B-Scan 2D images of the concrete test blocks were acquired using the simulated data and compared with experimental results acquired using an in-house developed four-channel ultrasonic imaging system. Both simulation and experimental results showed a good resemblance, indicating that B-Scan imaging can be applied to identify and characterise various types of defects and inclusions in underwater concrete structures, providing better assessment of the material than conventional ultrasonic pulse velocity (UPV) method. [ABSTRACT FROM AUTHOR]

High-Intensity Focused Ultrasound (HIFU) as a promising and impactful modality for breast tumor ablation, entails the precise focalization of high-intensity ultrasonic waves onto the tumor site, culminating in the generation of extreme heat, thus ablation of malignant tissues. In this paper, a comprehensive three-dimensional (3D) Finite Element Method (FEM)-based numerical procedure is introduced, which provides exceptional capacity for simulating the intricate multiphysics phenomena associated with HIFU. Furthermore, the application of numerical procedures to an anatomically realistic breast phantom (ARBP) has not been explored before. The integrity of the present numerical procedure has been established through rigorous validation, incorporating comparative assessments with previous two-dimensional (2D) simulations and empirical data. For ARBP ablation, the administration of a 0.1 MPa pressure input pulse at a frequency of 1.5 MHz, sustained at the focal point for 10 seconds, manifests an ensuing temperature elevation to 80°C. It is noteworthy that, in contrast, the prior 2D simulation using a 2D phantom geometry reached just 72°C temperature under the identical treatment regimen, underscoring the insufficiency of 2D models, ascribed to their inherent limitations in spatially representing acoustic energy, which compromises their overall effectiveness. To underscore the versatility of this numerical platform, a simulation of a more clinically relevant HIFU therapy procedure has been conducted. This scenario involves the repositioning of the ultrasound focal point to three separate lesions, each spaced at 3 mm intervals, with ultrasound exposure durations of 6 seconds each and a 5-second interval for movement between focal points. This approach resulted in a more uniform high-temperature distribution at different areas of the tumour, leading to the ablation of almost all parts of the tumour, including its verges. In the end, the effects of different abnormal tissue shapes are investigated briefly as well. For solid mass tumors, 67.67% was successfully ablated with one lesion, while rim-enhancing tumors showed only 34.48% ablation and non-mass enhancement tumors exhibited 20.32% ablation, underscoring the need for multiple lesions and tailored treatment plans for more complex cases. [ABSTRACT FROM AUTHOR]

Ultrasonic pulse velocity (UPV) test is widely used to evaluate rock mass integrity. However, it is rather difficult to conduct a sampling of fractured rocks and acquire a set of rocks with different fracture levels in experiments due to friability and heterogeneity. Consequently, numerical modeling on the UPV test of multi-fractured rock is carried out based on the discrete element method (DEM). A single fracture model and comparison between 2D and 3D models are first carried out for numerical verification. Subsequently, the UPV tests of multi-fractured rock are numerically investigated. The fracture system follows a power-law length distribution and is randomly allocated for fracture position and orientation. The influences of geometric fracture characteristics and related mechanical parameters on the wave velocity are discussed. Finally, a multi-parameter sensitivity analysis is performed. It is found that the 2D and 3D models of the UPV test have almost similar variation regularity at different fracture configuration conditions. Long fractures significantly influence the reduction of wave velocity in rock interior. The fracture intensity, long fracture proportion, and wave velocity value are linearly related. In contrast, the mechanical parameters including fracture stiffness and elastic modulus have a limited influence on the attenuation of ultrasonic waves especially at high stiffness and modulus range, and the power function model could fit the correlation between wave velocity and mechanical parameters. An inversion approach is proposed for estimating the fracture magnitude by adjusting the fracture intensity and long fracture ratio to match the target wave velocity value. Highlights: Ultrasonic wave velocity testing results for 2D and 3D fractured rock models were compared. Impacts of fracture geometric distribution characteristics and mechanical parameters on wave velocity were investigated. A fracture distribution inversion strategy based on wave velocity test is proposed as the future perspective based on the parameter sensitivity analysis. [ABSTRACT FROM AUTHOR]

We perform a resolvent analysis of a compressible turbulent jet, where the optimisation domain of the response modes is located in the acoustic field, excluding the hydrodynamic region, in order to promote acoustically efficient modes. We examine the properties of the acoustic resolvent and assess its potential for jet-noise modelling, focusing on the subsonic regime. Resolvent forcing modes, consistent with previous studies, are found to contain supersonic waves associated with Mach wave radiation in the response modes. This differs from the standard resolvent in which hydrodynamic instabilities dominate. We compare resolvent modes with SPOD modes educed from LES data. Acoustic resolvent response modes generally have better alignment with acoustic SPOD modes than standard resolvent response modes. For the optimal mode, the angle of the acoustic beam is close to that found in SPOD modes for moderate frequencies. However, there is no significant separation between the singular values of the leading and sub-optimal modes. Some suboptimal modes are furthermore shown to contain irrelevant structure for jet noise. Thus, even though it contains essential acoustic features absent from the standard resolvent approach, the SVD of the acoustic resolvent alone is insufficient to educe a low-rank model for jet noise. But because it identifies the prevailing mechanisms of jet noise, it provides valuable guidelines in the search of a forcing model (Karban et al. in J Fluid Mech 965:18, 2023). [ABSTRACT FROM AUTHOR]

Compared with traditional methods, cavitation-based processing technology has received extensive attention for its low energy consumption and high processing efficiency. The cavitation phenomenon releases high energy due to the generation and collapse of bubbles, which improves the efficiency of various food processing. This review details the cavitation mechanism of ultrasonic cavitation (UC) and hydrodynamic cavitation (HC), factors affecting cavitation, the application of cavitation technology in food processing, and the application of cavitation technology in the extraction of various natural ingredients. The safety and nutrition of food processed by cavitation technology and future research directions are also discussed. The mechanism of UC refers to longitudinal displacement of the particles of the medium induced by ultrasonic waves causing a series of alternating compression and rarefaction of particles, whereas HC occurs when liquid enters a narrow section and undergoes large pressure differentials, both of which can trigger the generation, growth, and collapse of microbubbles. Cavitation could be applied in microbial inactivation, and drying and freezing processing. In addition, cavitation bubbles can have mechanical and thermal effects on plant cells. In general, cavitation technology is a new sustainable, green, and innovative technology with broad application prospects and capabilities. [ABSTRACT FROM AUTHOR]

Cracks in concrete structures are unavoidable, resulting in the deterioration of concrete structures. An effective way to heal cracks, integrated with a suitable monitoring method, is of great significance. This research explores and demonstrates the autonomic healing and simultaneous ultrasonic monitoring of thin cracks using silica-based chemical agents. The sensitivity of ultrasonic waves to the change in the elastic properties of the medium through which it propagates is used to monitor the progressive healing of cracks in concrete. An increase in the ultrasonic pulse transmission (UPT) signal strength with the progression of healing in cracked concrete was used to interpret the condition of the crack. The ultrasonic results were validated by visual observations, an increase in compressive strength and a reduction in water permeability. Further, the efficacy of silica-based chemical healing agents in crack-healing concrete was also verified by microstructural scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests. The study successfully demonstrates the efficacy of sodium silicate as an effective chemical healing agent in cementitious materials, with the healing process well picked up by ultrasonic pulse transmission measurements. Practical Applications: The results of the study indicate that the utilization of sodium silicate as a healing agent in civil structures, integrated with the nondestructive monitoring of the healing process using the ultrasonic pulse transmission technique, represents an innovative approach to enhancing the durability and sustainability of concrete structures. Some practical applications include the following (1) the strength and life span of concrete bridges can be improved by integrating a crack repairing system with sodium silicate and monitoring through ultrasonic methods; (2) a sodium silicate solution can be injected into masonry substrate and mortar joints of historical buildings where cracks and weathering action have compromised the structural stability, and ultrasonic transducers can be strategically placed to monitor the healing progression and restoration process; and (3) this technique can be used to improve the resilience of marine structures by using sodium silicate as a healing solution in underwater concrete structures and combining it with ultrasonic monitoring. [ABSTRACT FROM AUTHOR]

In this paper, the attempts of measuring the thickness of a steel operation pipe occurring in the salt cavern and its geometry using an ultrasonic probe in the stage of computer simulation and laboratory are presented. The pipe makes as an obstacle for ultrasonic waves. In order to resolve this task, we need to determine the thickness of the pipe and choose the appropriate resonant ultrasonic wave. Determination of the thickness of the industrial steel pipes was carried out using the resonant frequency of reflected ultrasound waves and the relationship coefficients. The thicknesses of the industrial pipes measured by the resonant ultrasound wave method are in good agreement with those measured using an electronic caliper. Measurements of the cavern geometry with presence of the operation pipe using the resonant frequency of ultrasonic wave were well verified in a physical model and will be able in application to determine the real salt caverns. [ABSTRACT FROM AUTHOR]

This paper presents an innovative approach to high-temperature health monitoring of aircraft structures utilizing an ultrasonic guided wave transmission and reception system integrated with a zirconia heat buffer layer. Aiming to address the challenges posed by environmental thermal noise and the installation of heat buffers, which can introduce structural nonlinearities into guided wave signals, a composite guided wave consisting of longitudinal and Lamb waves was proposed for online damage detection within thermal protection systems. To effectively analyze these complex signals, a hybrid damage monitoring technique combining variational mode decomposition (VMD) and fuzzy entropy (FEN) was introduced. The VMD was employed to isolate the principal components of the guided wave signals, while the fuzzy entropy of these components served as a quantitative damage factor, characterizing the extent of the structural damage. Furthermore, this study validated the feasibility of piezoelectric probes equipped with heat buffer layers for both exciting and receiving ultrasonic guided wave signals in a dual heat buffer layer, a one-transmit-one-receive configuration. The experimental results demonstrated the efficacy of the proposed VMD-FEN damage factor for real-time monitoring of damage in aircraft thermal protection systems, both at ambient and elevated temperatures (up to 150 °C), showcasing its potential for enhancing the safety and reliability of aerospace structures operating under extreme thermal conditions. [ABSTRACT FROM AUTHOR]

Ultrasonic waves have been explored for fracturing coal seams to enhance Coalbed Methane (CBM) permeability, yet the underlying mechanics of ultrasonic cavitation are not fully understood. This study investigates the effect of water-based ultrasonic cavitation on coal pores microstructure by employing fluid invasion methods and non-destructive X-ray testing to reconstruct coal pore microstructures. Additionally, numerical simulations of ultrasonic cavitation development were conducted. The research examines how ultrasonic power influence evolution mechanism of cavitation effects in pores microstructure of water-bearing coal. Such insights lay a theoretical groundwork for improved Water-Based Ultrasonic Cavitation Enhanced Coalbed Methane Recovery (WUC-ECBM). Findings suggest that coal pores microstructure with a fully connected pore topology are more conducive to ultrasonic cavitation. As ultrasonic exposure increases, the accumulated waves cause coal pore microstructure cavitation bubbles to oscillate violently and non-linearly, leading to their growth, development, and collapse. This results in high-energy microjets and shockwaves, creating a high-temperature, high-pressure environment (reaching up to 35.69 MPa and 2729.77 K) favorable for improving gas desorption and migration. Ultrasonic power adjusts the cavitation threshold and intensity, facilitating gas migration. This research aims to improve gas desorption and migration in coal by capitalizing on the mechanical, physical, and thermal effects of ultrasonic cavitation. These findings offer theoretical support for the effective implementation of WUC-ECBM. [ABSTRACT FROM AUTHOR]

This article proposes a new algorithm for computing dispersion curves of ultrasonic guided waves in multi-layered composites with large number of layers. The algorithm is based on balancing the eigenvalue problem of the Spectral Collocation Method (SCM) formulation. The SCM has proven effective in analyzing single-layer and simple waveguides. However, it struggles with large multi-layer structures due to numerical instability caused by irregular and sparse matrices in the eigenvalue problem. The proposed algorithm for balancing has significantly reduced both the conditioning measure and the matrix norm in the matrix system. The optimization of spectral formulation enables accurate calculation of dispersion curves and characterization of displacement/stress profiles using Matlab software. This precise characterization and mode separation are essential for selecting ultrasonic sensors for damage detection. A comparison was made with Dispersion Calculator (DC) software. The algorithm was first validated using a hybrid multi-layered composite [CFRP-Al-CFRP-Al], which was successful. The validated algorithm was then quantitatively evaluated using a cross-play laminate T800M913 [0/90/0/90] in terms of three parameters: Number of collocation points, wave propagation direction and thickness. The algorithm is then applied to a large number of layers using three configurations: Symmetric layup T80M913[0/90]10s, hybrid layup [CFRP-Al]50 and challenging layup T800M913[0/90]100. The study found that the balancing algorithm, when combined with the SCM, is effective for structures with a large number of layers. Finally, optimizing the SCM will enhance its competitiveness as an effective tool in ultrasonic non-destructive testing for the studied structures of great industrial interest. [ABSTRACT FROM AUTHOR]

This paper introduces a novel design for a liquid-deployed Piezoelectric Micromachined Ultrasonic Transducer (PMUT). This design was specifically developed to resonate at a lower ultrasonic frequency than a PMUT with a circular, fully clamped diaphragm with the same diameter. Furthermore, the novel design was also optimised to enhance its ultrasonic radiation reception capabilities. These parametric enhancements were necessary to develop a PMUT device that could form part of an eventual microscale sensory device used for the Structural Health Monitoring (SHM) of reinforced concrete (RC) structures. Through these two enhancements, an eventual microscale sensor can be made smaller, thus taking up a smaller die footprint and also be able to be deployed further apart from each other. Eventually, this would reduce the developed distributed sensor system's cost. The innovative design employed a configuration where the diaphragm was only pinned at particular points along its circumference. This paper presents results from Finite Element Modelling (FEM), as well as experimental work that was conducted to develop and test this novel PMUT. The experimental work presented involved both laser vibrometry and ultrasonic radiation lab work. The results show that when compared to a clamped diaphragm design, the novel device managed to achieve the required reduction in resonant frequency and presented an enhanced sensitivity to incoming ultrasonic radiation. [ABSTRACT FROM AUTHOR]

The damage evolution process of layered rock is influenced by its fine structure, lamination direction, and confining pressure, exhibiting significant anisotropic characteristics. This study focuses on shale as the research object, employing indoor tests and theoretical analysis to define damage variables and initial damage based on ultrasonic wave velocity. This research investigates the damage evolution law of layered rock under varying confining pressures and dip angles. The findings reveal that damage variables defined using transverse wave velocity effectively reflect the damage evolution process. Additionally, confining pressure significantly affects damage evolution, with increasing pressure causing a rightward shift in the damage variable–strain curve and an increase in initial damage. The slab inclination angle also influences damage evolution; samples with 45° and 60° inclinations are more susceptible to damage, with initial damage showing a trend of increasing and then decreasing. To accurately describe the relationship between damage variables and strain during the loading process, this paper establishes a segmented damage evolution equation characterized by wave velocity. Initially, an inverse proportional function is employed to characterize the strain before crack closure. Subsequently, a logistic function represents the curve from crack strain to peak strain. This combined approach provides a comprehensive depiction of the damage evolution. This study underscores the importance of considering confining pressure and laminar inclination in the analysis of rock stability and integrity. These results provide critical insights into the damage evolution characteristics of layered rocks, offering valuable references for engineering safety assessments. [ABSTRACT FROM AUTHOR]

In addition to a recently acousto-optical deflector that has been the subject of both theoretical and experimental analysis, this work presents the successful processing of two acousto-optical deflectors that have been orthogonally positioned using two frequency-modulated ultrasonic waves. A comprehensive theoretical analysis is conducted, based on the Collins integral and the ABCD matrix formalism, to explain how the positions of the diffracted orders oscillate in two dimensions as a function of time. The numerical simulation of the derived formula demonstrates the potential for steering a laser beam along Lissajous trajectories. The trajectories in question are observed to exhibit a variety of shapes and velocities. They are sometimes linear with sinusoidal velocities, sometimes circular with constant velocities, and often elliptical with variable velocities. The noteworthy aspect is that all these diffracted orders traverse the spatial domain with an identical sweep frequency, despite the heterogeneity of their trajectories and velocities. Furthermore, these trajectories can be shaped by controlling the phase shift value. This technique can be employed in metrology for rotation measurements based on the Doppler effect. Additionally, it can be used to develop a spatial display that enables tracing Lissajous trajectories, rather than relying on an oscilloscope. [ABSTRACT FROM AUTHOR]