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Noncontact transportation and separation techniques using airborne ultrasound are attractive for use in industrial fields in which micrometer- to millimeter-sized objects can be levitated, rotated, and transported in the air using acoustic standing-wave and traveling-wave fields. This paper discusses a method to rotate a small object in the air without physical contact using ultrasound. The experimental system comprises a vibrating disk with four bolt-clamped Langevin-type ultrasound transducers and two semicircular reflectors. The flexural vibration of the disk generates an acoustic standing wave between them, and a small object can be levitated at the nodal position. An acoustic traveling wave was generated in the horizontal direction in an asymmetric acoustic field by inclining one of the two reflectors, which induced rotation of the object in the clockwise or counterclockwise direction. The acoustic intensity in the circumferential direction acting on the object was then calculated, and the directions of rotation predicted by the calculations corresponded with the experimental results. Higher input currents produced higher rotation speeds; the rotation speed reached a maximum value of 6.8 ± 0.9 rps at an input current of 1.1 App. [ABSTRACT FROM AUTHOR]

In order to investigate the steel fiber parameters on the damage characteristics and crack evolution of cellular concrete materials, uniaxial compression–acoustic emission combined tests were carried out on steel-fiber-reinforced cellular concrete (SFRCC) with different steel fiber contents (0%, 0.5%, 1%, 1.5%, and 2%) and different porosities (10% and 20%). The material damage evolution characteristics were analyzed by acoustic emission parameters and IB values, and the crack types were identified using Gaussian mixture clustering method (GMM) pairs. The results show the following: the inclusion of steel fibers increased the compressive strength of cellular concrete by 19.8~46.3% at 10% porosity, and by 37.1~102.2% at 20% porosity; the addition of steel fibers significantly increased the density and intensity of the acoustic emission signals; the decreasing tendency of the IB value at the peak stress slowed down with the increase in the amount of steel fibers, and the steel fibers could effectively inhibit the crack development; crack classification results show that the proportion of shear cracks in all stages of cellular concrete increased significantly after the addition of steel fibers. [ABSTRACT FROM AUTHOR]

With the goal of examining the micromechanics damage characteristics of freeze-thaw red sandstone under the influence of cyclic loads, a model of freeze-thaw cyclic rock particles is developed based on Discrete Element Method numerical simulation in order to investigate and study the micromechanics response mechanism of rocks under the coupling effect of freeze-thaw and cyclic loads. The findings demonstrate that lower rock elastic modulus and higher irreversible strain are driven by longer loading/unloading durations and more frequent freeze-thaw cycles. Its bearing capacity and resistance to deformation are diminished by the damage brought on by freeze-thaw; Rock anisotropy and the spatial organisation of microcracks are significantly altered by different loading techniques; In freeze-thaw rocks, the frequency and intensity of acoustic emission breaking follow the law of normal distribution. Under cyclic stress, samples exposed to several freeze-thaw cycles exhibit an escalation in large-scale fractures, accompanied by a concentrated spatial distribution of acoustic emission events. Three phases may be distinguished in the energy evolution of red sandstone: the initial, accumulation, and release phases. The energy storage capacity is compromised by freeze-thaw degradation, resulting in an elevated conversion rate of dissipative energy and rendering the energy conversion mechanism more unstable. The previously described study results possess considerable relevance for rock engineering construction and catastrophe mitigation in cold climates. [ABSTRACT FROM AUTHOR]

Intratumoral injections often lack visibility, leading to unpredictable outcomes such as incomplete tumor coverage, off-target drug delivery and systemic toxicities. This study investigated an ultrasound (US) and x-ray imageable thermosensitive hydrogel based on poloxamer 407 (POL) percutaneously delivered in a healthy swine model. The primary objective was to assess the 2D and 3D distribution of the hydrogel within tissue across three different needle devices and injection sites: liver, kidney, and intercostal muscle region. Secondly, pharmacokinetics of POL loaded with doxorubicin (POLDOX) were evaluated and compared to free doxorubicin injection (DOXSoln) with a Single End Hole Needle. Utilizing 2D and 3D morphometrics from US and x-ray imaging techniques such as Computed Tomography (CT) and Cone Beam CT (CBCT), we monitored the localization and leakage of POLDOX over time. Relative iodine concentrations measured with CBCT following incorporation of an iodinated contrast agent in POL indicated potential drug diffusion and advection transport. Furthermore, US imaging revealed temporal changes, suggesting variations in acoustic intensity, heterogeneity, and echotextures. Notably, 3D reconstruction of the distribution of POL and POLDOX from 2D ultrasound frames was achieved and morphometric data obtained. Pharmacokinetic analysis revealed lower systemic exposure of the drug in various organs with POLDOX formulation compared to DOXSoln formulation. This was demonstrated by a lower area under the curve (852.1 ± 409.1 ng/mL·h vs 2283.4 ± 377.2 ng/mL·h) in the plasma profile, suggesting a potential reduction in systemic toxicity. Overall, the use of POL formulation offers a promising strategy for precise and localized drug delivery, that may minimize adverse effects. Dual modality POL imaging enabled analysis of patterns of gel distribution and morphology, alongside of pharmacokinetics of local delivery. Incorporating hydrogels into drug delivery systems holds significant promise for improving the predictability of the delivered drug and enhancing spatial conformability. These advancements can potentially enhance the safety and precision of anticancer therapy. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusions One big challenge in the noninvasive high‐intensity focused ultrasound (HIFU) surgery is that the location and shape of its focus is unpredictable at the preoperative stage due to the complexity of sound wave propagation. The Acoustic Radiation Force Impulse (ARFI) imaging is a potential solution to this problem, but artifacts resulting from shear wave propagation remain to be solved.In this study, we proposed avoiding those artefacts by applying the ARFI technique at a high imaging frame rate within a very short time before the shear waves start to propagate.Using single transmission with a convex imaging probe, two ultrafast imaging modalities (the diverging wave and the wide beam), were developed in the ARFI framework, and their reliabilities were validated on a nylon string phantom by the centroid tracking method borrowed from ultrasound localization microscopy (ULM). The proposed ARFI method was tested on a clinically equivalent HIFU system under different acoustic radiation intensities by in‐vitro, ex‐vivo and in‐vivo experiments. In three experimental scenarios, we delivered short HIFU stimulation pulses at varying acoustic powers to induce tissue motion within the focal region. At each experimental site, both diverging wave and wide‐beam imaging techniques were employed for motion estimation. Based on the focus prediction derived from the motion estimation, HIFU ablation treatment was performed. The treated samples were then incised to examine the damaged areas. Additionally, ultrasound B‐mode images were acquired before and after the procedure and saved for analysis.Quantitative analysis showed that the ARFI with wide beam imaging was able to predict the HIFU focus preoperatively, only with 1 to 3 mm of errors in focal central location, and less than 23% of percentage errors in focal area in most cases. However, the diverging wave imaging failed to predict the HIFU focus due to its low signal‐to‐noise ratio.In conclusion, the inherent shear wave artefacts in ARFI for predicting the HIFU focus can be successfully avoided by carefully designing the imaging strategy and its working sequence. This ARFI technique was validated through a series of experiments on a clinically equivalent HIFU system, which demonstrated its capability in assisting surgical planning. [ABSTRACT FROM AUTHOR]

Prepulse inhibition of perceived stimulus intensity (PPIPSI) is a phenomenon where a weak stimulus preceding a stronger one reduces the perceived intensity of the latter. Previous studies have shown that PPIPSI relies on attention and is sensitive to stimulus onset asynchrony (SOA). Longer SOAs may increase conscious awareness of the impact of gating mechanisms on perception by allowing more time for attention to be directed toward relevant processing channels. In other psychophysiological paradigms, temporal predictability improves attention to task relevant stimuli and processes. We hypothesized that temporal predictability may similarly facilitate attention being directed toward the pulse and its processing in PPIPSI. To examine this, we conducted a 2 (SOA: 90 ms, 150 ms) × 2 (predictability: low, high) experiment, where participants were tasked with comparing the perceived intensity of an acoustic pulse‐alone against one preceded by a prepulse. The relationship between PPIPSI and cortical PPI (N1‐P2 inhibition) was also investigated. Significant main effects of temporal predictability, SOA, and cortical PPI were revealed. Under high temporal predictability, both SOAs (90 and 150 ms) elicited greater PPIPSI. The findings indicate that temporal predictability enhances the timely allocation of finite attentional resources, increasing PPIPSI observations by facilitating perceptual access to the gated pulse signal. Moreover, the finding that reductions in N1‐P2 magnitude by a prepulse are associated with increased probability of the participants perceiving the pulse "with prepulse" as less intense, suggests that under various experimental conditions, the link between these cortical processes and perception is similarly engaged. Consistent with other paradigms, our study reveals that temporal predictability enhances sensory gating of conscious perception, as evidenced by increased prepulse inhibition of perceived stimulus intensity (PPIPSI). This enhancement likely occurs through more efficient allocation of attention to sensory channels. Additionally, the link between N1‐P2 gating and PPIPSI suggests that the N1‐P2 response may inform perception. [ABSTRACT FROM AUTHOR]

Rock-like materials are often used in physical simulation tests to study deep dynamic disasters, such as rock bursts. In this study, a uniaxial compression failure test was conducted to investigate the impact tendency and damage characteristics of rock-like materials, and the evolution law of the acoustic emission and infrared thermal imaging during compression failure was revealed. First, the impact tendencies of rock-like materials and their acoustic emission and thermal imaging response characteristics during compression failure were analyzed. At the initial stage of loading, the acoustic emission intensity was low, and the average infrared radiation temperature exhibited a downward trend. With the gradual stress loading, the acoustic emission count and average infrared radiation temperature began to increase slowly but remained in a low frequency and low energy range. When the stress was close to the peak, the acoustic emission count and average infrared radiation temperature increased significantly with more evident low-frequency and high-energy signals. Second, the damage variable was defined based on the acoustic emission and infrared radiation temperature. An average infrared radiation cumulative temperature damage variable was proposed. The damage process of rock-like materials was divided into initial, stable, and accelerated stages. Finally, by comparing the damage variables defined by the different parameters and the damage constitutive model of rock-like materials, the rationality of the damage variables was verified. Considering that the Lemaitre constitutive equation ignored the compaction effect of rock-like materials, a correction coefficient K was introduced to reduce the deviation between the theoretical stress curve and the experimental curve. The results of this study provide theoretical support for studying the impact tendencies and damage characteristics of rock-like materials. Highlights: The impact tendency of rock-like materials is analyzed qualitatively and quantitatively. The average infrared radiation cumulative temperature damage variable is proposed. The rationality of the new damage variables is verified. [ABSTRACT FROM AUTHOR]

To mitigate the issue of vibration transfer from rotating mechanical components on satellites in orbit to essential systems, which can compromise their functionality. This study introduces a novel vibration-damping structure inspired by the energy dissipation mechanism observed in spiderwebs during prey capture. To investigate the distribution law and transfer properties of steady-state vibration energy propagated by longitudinal, shear, and bending waves on a spiderweb vibration-damped structure subjected to simple harmonic excitation, the structural acoustic intensity technique has been developed in a matrix format for potential utilization in the aerospace industry. This paper presents a developed model of a spiderweb vibration-damping structure subjected to simple harmonic excitation. The outcomes of finite element analyses are further analyzed using a compiled software tool to evaluate the efficiency of vibration energy transfer and power flow capacity of a spiderweb damping structure in comparison to a traditional plate. This analysis includes an examination of the impact of various factors such as coupling angle, damping coefficient, elastic modulus, and density on the vibration transfer characteristics of the spiderweb damping structure. Additionally, the study involves the visualization of the overall structural acoustic intensity distribution of the spiderweb damping structure in a steady-state condition when subjected to a simple harmonic excitation, as well as the structural acoustic intensity patterns of different types of vibration waves. Furthermore, the inherent physical connection between the structural sound intensity and the structural vibration properties is determined and examined using the equations of motion. The findings indicate that the spiderweb vibration-damping structure exhibits superior energy dissipation compared to the conventional plate structure; The spiderweb vibration-damping structure experiences various types of vibration wave conversion phenomena during the transmission process. Controlling structural vibration essentially involves managing the flow of vibration energy; Selecting the appropriate coupling angle and material characteristics can aid in minimizing the power transmission within the structure. [ABSTRACT FROM AUTHOR]

To optimize microbubble formulations for clinical applications, the size distribution, concentration, and acoustic intensity must be rapidly measurable to allow for the successful iteration of microbubble design. In this paper, a comprehensive method was developed to compare microbubble formulations with different lipid shell compositions using optical and acoustic methods of measurement to collect the size distribution, concentration, and mean scattering intensity. An open-source ImageJ macro code was modified for the selective counting and sizing of brightfield microbubble images. A high-throughput agarose phantom was designed to collect multiple scattering reflections of microbubble samples to estimate the echogenicity of each microbubble solution. The information contained in the size distribution and concentration, combined with the instantaneous scattering power, can identify modifications needed for prototyping specific microbubble formulations. [ABSTRACT FROM AUTHOR]

We have estimated the resource potential of cobalt-rich ferromanganese crusts (CFCs) on the summit area of the KC-8 seamount in the West Pacific, based on the acoustic backscatter intensity (ABI), ROV video footage, and CFC thickness measurements. To estimate the spatial distribution of CFC across 13 equally divided blocks within a 360 km2 area, shipboard and deep-tow ABIs were compared with visual data. The presence of CFCs is evident in the areas where ABI is higher than average, validating the use of ABI data to delineate the exposure of CFCs. With high accuracy in distinguishing between CFCs and sediment-dominant areas, the distribution area of CFCs was precisely calculated. The variation in CFC thickness across the KC-8 seamount summit was measured through CFC samples retrieved using a CFC corer. CFC thickness is highly variable even between adjacent sites, but it shows a roughly increasing trend from south to northwest. Based on the CFC distribution area associated with thickness, we calculated a CFC resource abundance. Of the estimation, 82% have remained on the gentle slope (<10°) areas, which can be accessible for future mining. Overall, our study suggests that the combination of an acoustic survey with reliable thickness information is highly effective in estimating CFC abundance. [ABSTRACT FROM AUTHOR]

This work presents a numerical method for modeling fluid–structure–acoustics interaction (FSAI) problems involving large deformation. The method incorporates an immersed boundary method and a regularized lattice Boltzmann method (LBM) where a multi-block technique and a nonreflecting boundary condition are implemented. The von Neumann analysis is conducted to investigate the stability of the regularized LBM. It is found that the accuracy and stability of the regularized LBM can be improved when the collision operator is computed from the Hermite polynomials up to the fourth order instead of the second order. To validate the present method, four benchmark cases are conducted: the propagation of an acoustic monopole point source, the sound generated by a stationary cylinder in a uniform flow, the sound generation of a two-dimensional insect model in hovering flight, and the sound generation of a three-dimensional flapping wing. Predictions given by the current method show a good agreement with numerical simulations and analytical solutions reported in the literature, demonstrating its capability of solving FSAI problems involving complex geometries and large deformation. Finally, the method is applied in modeling sound generation in vortex-induced vibrations of a rigid cylinder and a sphere. It is found that vortex-induced vibration can enhance the acoustic intensity by approximately four times compared to that of the stationary case for a cylinder. In contrast, both vibrating and stationary spheres exhibited relatively less intense noise, primarily within the wake. Notably, the spanwise noise propagation is only observed when the sphere is vibrating. [ABSTRACT FROM AUTHOR]

In the present paper, the paramount characteristics of the resonance of cylindrical bubbles in a compressible liquid are theoretically investigated with multi-scale analysis. Considering the liquid's compressibility, a dimensionless equation of the cylindrical bubble wall motion is established for the primary resonance under a single-frequency acoustic field. Comparing with the numerical results, the present analytical solution is verified in terms of accuracy. The key parameters on the characteristics of primary resonance are further explored including the equilibrium bubble radius, dimensionless amplitude of the acoustic field, and other detuning parameters. The main conclusions are given as follows: (1) During primary resonance, three typical nonlinear phenomena are observed: multivalued solutions, jumps, and hysteresis phenomena. (2) The liquid's compressibility affects the intensity of acoustic waves emitted by the bubbles during primary resonance. The maximum pressure at the bubble interface in the incompressible liquid is higher than that in the compressible liquid. (3) In the amplitude–frequency curve, the unstable region of the compressible liquid is smaller and the peak is lower than in the incompressible liquid. [ABSTRACT FROM AUTHOR]

Gas extraction is crucial for coal mine safety, yet pipeline blockages by solid slag and water severely hinder efficiency and pose risks. Traditional detection methods are limited by rapid signal attenuation and noise interference. In this study, an acoustic detection technology is introduced for pipeline blockages, utilizing sensors at potential blockage points to collect sound wave data. Experiments with a scaled pipeline model reveal that slag blockages produce characteristic peaks in the 1200 Hz–2000 Hz range, while water blockages show peaks in the 1 kHz–2 kHz and 3.5 kHz–4.5 kHz bands. The longitudinal blockage intensity and extraction pressure significantly affect the sound pressure levels. A reliable fitting model predicts the blockage intensity based on acoustic signals, achieving high accuracy. This novel method enhances blockage identification, offering a non-invasive, cost-effective solution that improves coal mine safety and efficiency. [ABSTRACT FROM AUTHOR]

An experimental investigation has been made into the effects of a high-intensity impact on the pH value and temperature of water. Water pH and temperature dynamics has been determined at various regimes of acoustic impact on the specimens. Acoustic impact regimes have been established at which there is a maximum rise in the pH value and a drop in temperature. The dependence of the heat transfer rate on the intensity of acoustic vibrations has been defined. A comparison has been made of the obtained experimental results on variation of water pH in cooling with a known dependence. The results obtained in this investigation have been compared with experimental data of other authors who have investigated the behavior of water pH in ultrasonic, laser, electromagnetic, and mechanical impacts. [ABSTRACT FROM AUTHOR]

In a recent study using 3-D fullwave simulations, it was shown for a nonhuman primate model that a helmet-shaped 3D array of 128 transducer elements can be assembled for neurostimulation in an optimized configuration with the accommodation of an imaging aperture. Considering all acoustic losses, according to this study, for a nonhuman primate skull, the assembly of the proposed transducers was projected to produce sufficient focusing gain in two different focal positions at deep and shallow brain regions, thus providing sufficient acoustic intensity at these distinct focal points for neural stimulation. This array also has the ability to focus on multiple additional brain regions. In the work presented here, we designed and fabricated a single 15 mm diameter capacitive micromachined ultrasonic transducer (CMUT) element operating at 800 kHz central frequency with a 480 kHz 3 dB bandwidth, capable of producing a 190 kPa peak negative pressure (PNP) on the surface. The corresponding projected transcranial spatial peak pulse average intensity (ISPPA) was 28 Wcm−2, and the mechanical index (MI) value was 1.1 for an array of 128 of these elements. [ABSTRACT FROM AUTHOR]

For a low-frequency sound signal propagating in a horizontally inhomogeneous waveguide in shallow water, the influence of a fluctuating interface between the water layer and fluid bottom sediments was studied based on statistical modeling using the cross-sectional method. The modeling was carried out for hydrological conditions in many situations corresponding to the shallow shelf zones of the Russian Arctic seas. A specific feature of these water areas is the presence of an almost homogeneous water layer on poorly consolidated bottom sediments with various characteristics, including a high degree of gas saturation. The dependence of the average intensity of the sound signal and its individual modes on the parameters of the problem has been studied: the characteristic scale of fluctuations of the interface and impedance of this interface, which determines its penetrable properties. It is shown that the influence of bathymetric fluctuations on the average intensity of acoustic modes has its own characteristics versus the influence of random volumetric inhomogeneities of the sound speed in the water layer and sediments, established earlier. Thus, bottom roughness of a relatively small scale leads, on average, to increased attenuation of a sound signal when propagating in a waveguide, and this can occur at relatively short distances from the source. An increase in the reflectivity of a rough bottom boundary weakens the effect of increased sound attenuation so that for typical values of sound speed in the bottom, attenuation at distances of 10–20 km from the source differs little from that for an undisturbed horizontal boundary. [ABSTRACT FROM AUTHOR]

Conventional gunshot detection systems can quickly and reliably detect gunshots in the area where the acoustic sensors are placed. This paper presents the detection of weak hunting gunshots using the short-term entropy of signal energy computed from acoustic signals in an open natural environment. Our research in this field was primarily aimed at detecting gunshots fired at close range with the usual acoustic intensity to protect wild elephants from poachers. The detection of weak gunshots can extend existing detection systems to detect more distant gunshots. The developed algorithm was optimized for the detection of gunshots in two categories of the surrounding sounds, short impulsive events and continuous noise, and tested in acoustic scenes where the power ratios between the weak gunshots and louder surroundings range from 0 dB to −14 dB. The overall accuracy was evaluated in terms of recall and precision. Depending on impulsive or noise sounds, binary detection was successful down to −8 dB or −6 dB; then, the efficiency decreases, but some very weak gunshots can still be detected at −13 dB. Experiments show that the proposed method has the potential to improve the efficiency and reliability of gunshot detection systems. [ABSTRACT FROM AUTHOR]

This paper aims to explore the influences of prosody on (im)politeness perception in intercultural communication. Based on empirical data collected in perceptual experiments, the paper compares the perception of the (im)politeness prosodic properties of L1 German speakers and L2 German speakers of Chinese origin. It was found that the two subject groups show clear distinctions in their (im)politeness perceptions and that prosodic features exert different impacts on (im)politeness perception: L2 German speakers of Chinese origin perceive lower acoustic intensity, more pauses, and lower muscle tension as indicators of higher level of politeness, whereas the opposite holds true for L1 German speakers. In addition, the former demonstrate higher sensitivity to speech rate and modal particle stress than the latter. The study's findings indicate that (im)politeness and prosody perception are influenced by people's first language and home-grown culture, and a prosodic mitigation strategy may not be fully applicable in intercultural communication. [ABSTRACT FROM AUTHOR]

The impedance matching is essential in producing high-intensity acoustic waves. This paper studies the impedance calculation methods of modulators and double-chamber Helmholtz resonators based on fluid mechanics, aeroacoustics, and electro-acoustic analogy principles. The results: ① The impedance expression of the resonators is derived. ② The impedance variation law of the chamber volume, the stator size, the air supply pressure, the air supply flow, and the working frequency is calculated. ③ The impedance-matching design scheme of the two-chamber Helmholtz low frequency and high acoustic intensity generator is given. Based on the experimental results of the high acoustic intensity generating device that the author has manufactured in the closed space, the correctness of the impedance calculation and matching design scheme in this paper is verified. This method has guiding significance for the design of high-intensity acoustic generating devices in confined space. [ABSTRACT FROM AUTHOR]

Underwater acoustic vector sensors (UAVSs) are increasingly utilized for remote passive sonar detection, but the accuracy of direction-of-arrival (DOA) estimation remains a challenging problem, particularly under low signal-to-noise ratio (SNR) conditions and complex background noise. In this paper, a comprehensive theoretical analysis is conducted on UAVS signal preprocessing subjected to gain-phase uncertainties for average acoustic intensity measurement (AAIM) and complex acoustic intensity measurement (CAIM)-based vector DOA estimation, aiming to explain the theoretical restrictions of intensity-based vector acoustic preprocessing approaches. On this basis, a generalized vector acoustic preprocessing optimization model is established in which the principle can be described as "maximizing the denoising performance under the constraints of an equivalent amplitude-gain response and phase-bias response". A novel vector acoustic preprocessing method named linear matched stochastic resonance (LMSR) is proposed within the framework of matched stochastic resonance theory, which can naturally guarantee the linear gain-phase restrictions, as well achieving effective denoising performance. Numerical analyses demonstrate the superior vector DOA estimation performance of our proposed LMSR-AAIM and LMSR-CAIM methods in comparison to classical intensity-based AAIM and CAIM methods, especially under low-SNR conditions and non-Gaussian impulsive noise circumstances. Experimental verification conducted in the South China Sea further verifies its the effectiveness for practical application. This work can lay a solid foundation to break through the challenges of underwater remote vector acoustic DOA estimation under low-SNR conditions and complex ocean ambient noise and can provide important guidance for future research work. [ABSTRACT FROM AUTHOR]

Spatiotemporal variability of the low-frequency sound field in a coastal wedge in the presence of an internal Kelvin wave (IKW) is studied both experimentally and theoretically. The experiments were carried out in Lake Kinneret, Israel (also known as the Sea of Galilee) in August 2021, with a wideband sound source deployed near the shore and receiving vertical line arrays located at the lake's center. Parameters of the IKW were obtained earlier from long-term thermistor string measurements combined with conductivity, temperature, and depth data. The IKW initiated range-dependent vertical displacements of the thermocline with a maximum amplitude near the shore and almost zero amplitude in the center of the lake. It corresponded to a thermocline inclination angle of ±0.08° with respect to the horizontal. Temporal variations in depth-averaged acoustic intensity, reaching almost 8 dB, and remarkable changes in the normal mode composition were registered. These effects are explained based on simulations using a parabolic equation and normal mode models. The role of mode coupling in acoustic intensity variations is assessed. [ABSTRACT FROM AUTHOR]

Traditionally, honking capture system calibration has primarily involved indoor experiments in muffler rooms. Additionally, the manual measurement method for estimating positioning errors in vehicle honking detection systems is not only susceptible to complex backgrounds in acoustic intensity pseudo-color image but also inef- ficient. Therefore, a value error estimation method based on YOLOX is proposed in this article to estimate the positioning error of the honking detection system. Firstly, the definitions for the horizontal positioning error and the vertical positioning error are provided. Afterwards, CBAM is added in YOLOX network for predicating the honking sound source position and the center of pixel coordinates of pseudo-color images. Based on YOLOX neural network model, a network model for vehicle detection in optical image is trained. Then, the color information from pseudo-color image with vehicles' pixel coordinates is combined to calculate the positioning error. Subsequently, the coordinate system conversion model is established according to the on-site installation information, and the corresponding world coordinates are obtained by combination with the geometric deduction method, to work out positioning error. Ultimately, the outdoor experiment of static and dynamic positioning error of detection systems for vehicle honking is launched. The result indicates that the mean average precision of the improved YOLOX network is up to 98.78%. Besides, the static horizontal positioning error of sound source localization never exceeds 0.15 m, and longitudinal positioning error is 0.31 m. The results show that the positioning error estimation method proposed in this article is helpful for the calibration of the honking detection systems. [ABSTRACT FROM AUTHOR]

This comprehensive review delves into the utilization of ultrasound for hydrogen generation, emphasizing the key mechanisms and techniques involved. One of the focal points of the study is the exploration of the generation and detection of cavitation bubbles, which are induced by ultrasound waves. An in-depth overview of various experimental setups that employ ultrasound technology for hydrogen production is also provided. A comparative analysis of these setups reveals differences in crucial parameters such as acoustic intensity, liquid temperature, and frequency. These are the key parameters identified as significant determinants affecting the hydrogen yield and efficiency. This review paper also highlights the potential applications of sonohydrogen as a viable energy resource. While challenges such as the high costs of ultrasound equipment and the need for efficient catalysts exist, the inherent benefits make sonohydrogen a compelling subject for future research and development. The study shows that there is no one-size-fits-all approach, accentuating the importance of understanding these parameters for optimizing the process of hydrogen production. Although the technology is primarily in the experimental phase, existing research indicates that the sonohydrogen production holds considerable potential for large-scale applications. [Display omitted] • The study explores ultrasound's role in enhancing hydrogen production. • The article reviews various experimental setups and comparing them. • The manuscript identifies key parameters affecting sonohydrogen production. • The study discusses the potential dimensions of sonohydrogen options and future research directions. • It examines scaling sonohydrogen production challenges for industrial use. [ABSTRACT FROM AUTHOR]

Inspired by a critical organelle called rough endoplasmic reticulum (RER), a wave‐energy attenuation nano‐carbon foam (WANF) with a unique hierarchical composite structure consisting of 3D‐lamelle, 2D‐perforations and 1D‐microspheres is constructed by incorporating graphene oxide (GO) and polydimethylsiloxane (PDMS) into a carbon nanotubes (CNTs)‐based aerogel. Benefiting by unusual mechanisms like vortex shedding, secondary reflection and resonance, WANF displays excellent acoustic wave absorption, achieving a sound absorption coefficient of over 0.9 with a bandwidth of 4.75 kHz at a thickness of 20 mm. Significantly, it features obvious acoustic absorption intensity in medium‐low frequency range. Moreover, the nano‐carbon aerogel skeleton (NCAS) of WANF endows it with good electromagnetic wave absorption through dielectric loss, exhibiting a minimum reflection loss of −48.61 dB and an efficient electromagnetic absorption with a bandwidth of 5.35 GHz. The excellent wave‐energy attenuation performance of WANF indicates an attracting double‐stealth effect in sonic and electromagnetic area, which shows great potential in integrate protection of advanced military equipment and sensitive electronic infrastructures. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on promoting osseointegration around dental implants. Study selection: A comprehensive search was performed on two databases, including MEDLINE (PubMed) and Web of Science to identify relevant studies published before June 1, 2022. Randomized controlled trials that met the inclusion criteria were selected for the study. The year of publication, study design, animal species, number of animals, number of implants, implant position, implant size, intervention, follow-up time, bone volume ratio (BV/TV), bone-implant contact ratio (BIC), and implant removal torque value (RTV) measurements, including mean and SD, were extracted. Results: Ten randomized trials were included in this meta-analysis. The results showed that LIPUS significantly promoted osteogenesis around dental implants. Furthermore, in animal models of pre-existing diseases such as osteoporosis and diabetes, LIPUS had the same effect. The included data were divided into subgroups to explore the effects of different follow-up time, acoustic intensities, and frequencies. Results showed that higher acoustic intensities and frequencies significantly improve the osteogenic effects of LIPUS. There was some degree of heterogeneity owing to bias in the included studies. More high-quality randomized controlled trials are necessary in the future. Conclusions: LIPUS can promote bone healing around dental implants and is an attractive option for edentulous patients, especially those with pre-existing diseases. Further clinical trials on the use of LIPUS in implant dentistry are warranted. Furthermore, future studies must pay more attention to acoustic intensity and frequency. [ABSTRACT FROM AUTHOR]

The sterilization of liquid eggs plays a crucial role in the production of liquid egg products. Traditional pasteurization techniques can easily cause protein denaturation, while non-thermal sterilization techniques are often constrained by processing intensity and time. Improving the effectiveness of liquid egg sterilization while preserving the stability of its functional attributes poses a significant challenge. In response to this issue, a synergistic ultrasonic mild thermal sterilization system for liquid eggs is proposed, accompanied by the optimization of its process parameters. COMSOL is employed to simulate the acoustic field distribution of the ultrasonic–thermal system in the liquid egg medium. Verification is conducted through acoustic intensity measurements, and analysis is performed to obtain the optimal arrangement of ultrasonic transducers. Based on Modbus communication, an ultrasonic–thermal synergistic sterilization system is designed. Sterilization experiments are conducted with both 20 kHz + 28 kHz and 20 kHz + 40 kHz multifrequency ultrasound, compared with traditional 20 kHz single-frequency ultrasound. The results indicate that multifrequency ultrasound improves sterilization efficiency by approximately 15% compared to traditional single-source ultrasound. Utilizing multifrequency ultrasonic–thermal synergistic sterilization experiments, a three-factor, three-level response surface test is conducted with sterilization rate and foaming properties as evaluation criteria. The results indicate a strong correlation between ultrasonic frequency, processing time, heating temperature, and sterilization performance, with the impact magnitude being sterilization temperature > processing time > ultrasound frequency. Parameter optimization analysis is performed using a genetic algorithm, yielding sterilization conditions of 55 °C, 11 min and 30 s processing time, and 20 + 40 kHz ultrasonic frequency. The liquid egg sterilization rate is 99.32%, an average decimal reduction of 3.17 log values, and foaming properties are 42.79%.Through comparative analysis, it is determined that the sterilization rate of the ultrasonic–thermal synergistic sterilization system meets national standards, and functional properties such as foaming are superior to traditional pasteurization. This validates the proposed ultrasonic–thermal synergistic liquid egg sterilization control system as effective and feasible. [ABSTRACT FROM AUTHOR]

Due to the sensitivity of the sonochemical production to the different operating conditions, in the present paper, a microscopic investigation is conducted to evaluate the impact of methanol concentration on the bubble temperature and hydroxyl radicals yielding. This analysis has been conducted by spanning a range of ultrasound frequency (from 140 to 515 kHz), acoustic intensity (1 and 2 W/cm2), and liquid temperature (from 10 to 50°C). Whatever the used frequency (140–515 kHz), the variation of bubble temperature and OH formation has been negatively impacted in the presence of methyl alcohol, with a plateau from 0.1 mM methanol. On the other side, the evolution of the peak temperature and OH production were found to be frequency dependent. Moreover, in the absence of methanol, the formation of hydroxyl radicals is in the same order as that of bubble temperature (50 > 40 > 30 > 20 > 10°C), whereas, in the presence of methanol, an optimal production of OH is obtained at 20°C for all methanol concentrations. The decrease in bubble temperature was accelerated with the rise of liquid temperature, where no sono-activity is obtained at the liquid temperature of 50°C. Based on the effects of wave frequency, acoustic intensity, and the liquid temperature, it has been concluded that the inhibition process of methanol alcohol toward the OH radicals is predominantly taking place at the bubble interface (bubble/solution region) rather than the cavitation interior (gas phase). [ABSTRACT FROM AUTHOR]

Coaxial coupling between two quasi-perfect ultrasonic vortices (QPUVs) with distinct ring radii and topological charges (TCs) has been suggested and implemented to create ultrasonic braided ring beams (UBRBs). It is possible to switch between a double-ring pattern, a braided ring pattern, and a petal-like pattern in the linked ultrasonic field distribution by varying the coupling strength of two QPUVs. We focus on the braided ring pattern and investigate the influence of TCs on the acoustic intensity and phase distributions. It is found that the UBRB contains multiple individual phase singularities, and the number of singularities is determined by the TCs of the two QPUVs. Furthermore, a phase modulation metasurface (PMM) composed of photosensitive resin cubes is well designed to produce the UBRB in water. The effectiveness of the single-layer PMM in producing the UBRB is confirmed by both simulations and experimental results. The proposed UBRBs based on metasurfaces could potentially have uses in multi-particle manipulation and acoustic communication. [ABSTRACT FROM AUTHOR]

A long-standing quest in audition concerns understanding relations between behavioral measures and neural representations of changes in sound intensity. Here, we examined relations between aspects of intensity perception and central neural responses within the inferior colliculus of unanesthetized rabbits (by averaging the population's spike count/level functions). We found parallels between the population's neural output and: (1) how loudness grows with intensity; (2) how loudness grows with duration; (3) how discrimination of intensity improves with increasing sound level; (4) findings that intensity discrimination does not depend on duration; and (5) findings that duration discrimination is a constant fraction of base duration. [ABSTRACT FROM AUTHOR]

Sonoporation has garnered significant attention for its potential to temporarily permeabilize cell membranes through the application of ultrasound waves, thus enabling an efficient cellular uptake of molecules. Despite its promising applications, the precise control of sonoporation remains a complex and evolving challenge in the field of cellular and molecular biology. This review aims to address two key aspects central to advancing our understanding of sonoporation. Firstly, it underscores the necessity for the establishment of a standardized methodology to validate and quantify the successful entry of molecules into target cells. This entails a critical examination of existing techniques and the identification of best practices to ensure accurate, reliable, and reproducible results. By establishing a common framework for assessing sonoporation outcomes, researchers can enhance the reliability and comparability of their experiments, paving the way for more robust findings. Secondly, the review places particular emphasis on the detailed analysis of various acoustic parameters as reported in the papers selected from the literature. Among these parameters, acoustic intensity (specifically, ISPTA) emerges as a pivotal factor in sonoporation studies. Furthermore, this review delves into the exploration of the elastic modulus and its significance in sonoporation mechanisms and associated challenges. This knowledge can inform the development of more effective strategies to optimize sonoporation protocols. In summary, this review not only highlights the pressing need for a standardized approach to verify molecule entry into cells but also delves into the search for an effective frequency and acoustic intensity for in vivo and in vitro applications. [ABSTRACT FROM AUTHOR]

Introduction: Photoacoustic imaging (PAI) uses nonionizing radiation for tumor features and thus can be used as an alternative method for medical features without inducing biological effects. The study aimed to characterize a PAI system utilizing a 650-nm diode laser to detect pathological conditions (benign and malignant tumors) in human uterine tissue, including healthy tissue. The benign tumor tissue used is a leiomyoma, which is a benign tumor that occurs in the middle layer of the uterine (myometrium). Meanwhile, the malignant tumor tissue used is a type of endometrial carcinoma, which is a malignant tumor that occurs in the inner layer of the uterine (endometrium). Methods: The human uterine tissue was obtained from the hysterectomy procedure conducted to determine the histopathological diagnosis. The PAI system uses a condenser microphone as the acoustic signal detector and a diode laser as the radiation source. Results: The characterization results of the PAI based on a diode laser with a wavelength of 650 nm and power of 250 mW showed an optimal performance for human uterine tissue in a laser modulation frequency of 16 500 Hz and a duty cycle of 50%. Obtained photoacoustic images could differentiate between healthy uterine, leiomyoma, and endometrial carcinoma tissues, as indicated by the intensity level values in each tissue type. Healthy uterine, leiomyoma, and endometrial carcinoma tissues had intensity values of 11.87, 26.84, and 37.26 a.u, respectively. A One-way ANOVA test with Bonferroni post hoc analysis revealed a significant difference in the acoustic intensity level between the groups (P < 0.05). Conclusion: The resulting intensity levels indicate a direct correlation with the nature of uterine tumors. The poorer the differentiation, the higher the resulting intensity. [ABSTRACT FROM AUTHOR]

Low-intensity focused ultrasound stimulation (LIFUS) has been proved effective in eliciting vibrotactile in addition to warm, cold and nociceptive pain when applied to human peripheral endings. However, if it can evoke fine tactile sensations has been rarely investigated by far despite the importance of fine tactile feedback in motor control. To explore this issue, 14 healthy volunteers were recruited in this study. A psychophysical experiment was firstly conducted to determine the appropriate range of pulse repetition frequency (PRF) and acoustic intensity (AI). Then, participants were asked to perceive and discriminate different tactile stimulations under LIFUS, so as to evaluate if multiple fine tactile sensations could be reliably elicited by modulating the PRF and AI. For objective assessment, the local blood perfusion volume (BPV) response beneath stimulated fingertip was recorded and characterized. Our results showed that four types of tactile sensations, including tapping, vibrating, electrical, and pressure could be reliably elicited by modulating the PRF and AI within a specific range, and there was a significant impact of PRF and AI on both participants’ tactile discrimination and amplitude features of BPV response. This study would facilitate the application of LIFUS to some human-machine interaction scenarios, and shed valuable insights on the physiological mechanisms of peripherally applied ultrasound stimulation. [ABSTRACT FROM AUTHOR]

Acoustically‐driven bubbles at the micron scale can generate strong microstreaming flows in its surrounding fluidic medium. The tunable acoustic streaming strength of oscillating microbubbles and the diversity of the generated flow patterns enable the design of fast‐moving microrobots with multimodal locomotion suitable for biomedical applications. The acoustic microrobots holding two coupled microbubbles inside a rigid body are presented; trapped bubbles inside the L‐shaped structure with different orifices generate various streaming flows, thus allowing multiple degrees of freedom in locomotion. The streaming pattern and mean streaming speed depend on the intensity and frequency of the acoustic wave, which can trigger four dominant locomotion modes in the microrobot, denoted as translational and rotational, spinning, rotational, and translational modes. Next, the effect of various geometrical and actuation parameters on the control and navigation of the microrobot is investigated. Furthermore, the surface‐slipping multimodal locomotion, flow mixing, particle manipulation capabilities, the effective interaction of high flow rates with cells, and subsequent cancerous cell lysing abilities of the proposed microrobot are demonstrated. Overall, these results introduce a design toolbox for the next generation of acoustic microrobots with higher degrees of freedom with multimodal locomotion in biomedical applications. [ABSTRACT FROM AUTHOR]

The paper presents a three-dimensional numerical study of the acoustic streaming induced by the dissipation of ultrasounds during their propagation in the air. The waves are generated by a circular acoustic source positioned at the center of the left wall of a parallelepipedic cavity. The simulations are performed with the lattice Boltzmann method associated with the D3Q19 multiple relaxation time model. A validation of this model is first performed by comparing the numerical and analytical acoustic intensities along the central axis of the acoustic source. The main objective of this study is to use two different methods to calculate the acoustic streaming flow. The first method is the direct calculation of the mean velocity fields as the mean values of the instantaneous velocities. The second method is an indirect technique, which first calculates the acoustic streaming force and then injects this force into the numerical code to produce the streaming. A comparison between the results obtained by the two methods was carried out and a good agreement was found between them. These different investigations, rather new in three-dimensional configurations, have allowed us to discuss the advantages and limitations of the lattice Boltzmann approach to simulate real situations of wave propagation and acoustic streaming. [ABSTRACT FROM AUTHOR]

Sixty-nine participants made continuous response judgments of perceived arousal and valence while listening to 30-s extracts of 100 unfamiliar pieces within a novel recommender system. Our purpose was to take advantage of the relatively large number of participants and pieces studied (compared with prior work on time series analysis [TSA] of continuous affective responses to music) to test the generality of the deductions made from prior evidence in smaller studies. Accordingly, we expected highly autoregressive responses, and hypothesized that acoustic intensity fluctuation would be a major (population-wide, fixed-effect) predictor of arousal and to a lesser degree valence responses in multivariate models, operating in conjunction with broad features of the spectral profile of the music (such as spectral flatness and centroid). We expected considerable interparticipant variability and were interested in the degree to which there was also interpiece variability (both being features of group-specific, random effects). The basic expectations were supported, and we also demonstrated, partly by means of a novel use of cluster analysis, that the observed group variabilities in response features could not be readily attributed to indices of a range of participant-preference and piecefeature characteristics, determined prior to the experiments. A Bayesian analysis was developed, possibly for the first time in the TSA of continuous affect responses to music, since it provides a more comprehensive description of the parameters of the analysis (not only their best estimate point values) and their effects, and a comprehensive range of tests for meaningful effects. [ABSTRACT FROM AUTHOR]

Alberini et al. have developed a new technology based on a passive acoustic emission (AE) sensing system that uses only a single sensor, with the goal of providing live and in‐situ measurement of rheology. For this study, three different types of fluids were selected to represent common rheological behaviours: Newtonian behaviour, non‐Newtonian behaviour with power law, and non‐Newtonian behaviour with Herschel–Bulkley relationship. By analyzing the transient energy released during the interaction between the probe and the fluid, distinct acoustic fingerprints were identified in the frequency domain. These acoustic fingerprints were found to be characteristic of the different fluids and their rheology, and were validated in triplicate. Furthermore, the results showed that the intensity of the acoustic emissions increased with higher flow rates (30 to 50 L/min). To test the correlation between flow rate and acoustic response, a neural network regression test was conducted, which demonstrated a direct correlation between AE peaks and flow rate. The neural network used was nonlinear autoregressive network with exogenous inputs (NARX), and the test involved a stepwise regression with 70% training and 30% network validation. The study also introduced the Rheology‐AE quotient, which maps fluid constituents against the acoustic signal. Results showed that this was a reliable means of deriving live rheology from a fluid's frequency domain. Finally, the results obtained from this study were validated using an offline rotational rheometer. [ABSTRACT FROM AUTHOR]

Classification of suspended particles characterizes the composition of seawater, which helps the interpretation of remote sensing data and promotes the researches of the matter exchanges in ocean processes. In this article, an in situ prototype based on polarized light scattering is introduced, and its ability to classify the suspended particles is demonstrated. The experimental results show that the prototype can classify the sediments, microplastics, and phytoplankton in seawater with an accuracy larger than 85%, and further calculate their relative proportion in water. In the summer and winter of 2020, the prototype was deployed three times in Daya Bay and lasted for dozens of hours each time, along with the additional commercial sensors, that is, Environment X Observation (EXO) and Acoustic Doppler Current Profiler (ADCP). The chlorophyll content measured by EXO and the acoustic backscatter intensity measured by ADCP are respectively related to the number of algal cells and sediments in the water, which helps to interpret the data of the prototype. The results of field data show that the prototype can effectively classify phytoplankton and sediment particles in seawater and monitor their temporal variations. Besides, the retrieved information of the suspended particles is consistent with the analysis from the flow dynamics and season variations in Daya Bay. These results indicate the ability of this prototype to classify the suspended particles in seawater, which promises its potential contribution to particulate oceanography in the future. [ABSTRACT FROM AUTHOR]

Abstract A statistical inversion method of estimating normal mode interference spectral parameters (including waveguide invariance and interference frequency) from one‐dimensional broadband sound intensity spectrum (1D BSIS) is presented. First, the interference phase of 1D BSIS is compensated by a non‐linear factor for each pair of unknown parameters in a prior parameter space. Second, the singular value decomposition is performed for a data matrix, which is constructed by the phase‐compensated BSIS. Then, a misfit function is defined based on both the maximum singular value and the corresponding singular vector of the data matrix. Finally, the posterior probability distributions of unknown parameters are analysed based on statistical inversion theory. This method is suitable for the situation using a single receiver and without any environmental information. Numerical simulations illustrate the validity of the presented method.

In this paper, an approach to perform leak state detection and size identification for industrial fluid pipelines with an acoustic emission (AE) activity intensity index curve (AIIC), using b-value and a random forest (RF), is proposed. Initially, the b-value was calculated from pre-processed AE data, which was then utilized to construct AIICs. The AIIC presents a robust description of AE intensity, especially for detecting the leaking state, even with the complication of the multi-source problem of AE events (AEEs), in which there are other sources, rather than just leaking, contributing to the AE activity. In addition, it shows the capability to not just discriminate between normal and leaking states, but also to distinguish different leak sizes. To calculate the probability of a state change from normal condition to leakage, a changepoint detection method, using a Bayesian ensemble, was utilized. After the leak is detected, size identification is performed by feeding the AIIC to the RF. The experimental results were compared with two cutting-edge methods under different scenarios with various pressure levels and leak sizes, and the proposed method outperformed both the earlier algorithms in terms of accuracy. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor target direction finding accuracy of conventional complex acoustic intensity method under the condition of low SNR(Signal-to-Noise Ratio), an underwater target direction finding method based on vector hydrophone single channel instantaneous phase difference weighting is proposed in this study. According to the characteristics that the instantaneous phase difference corresponding to the line spectrum frequency unit of underwater target is relatively stable and the instantaneous phase difference corresponding to the background noise frequency unit changes randomly, the variance weighting of the instantaneous phase difference of each channel frequency unit of vector hydrophone is carried out to enhance the SNR gain of the line spectrum and effectively restrain the energy interference of the background noise, thus realizing the high precision direction finding of underwater target. Simulation analysis and experimental verifications show that the direction finding accuracy of the proposed method is 15.8% higher than that of the conventional complex acoustic intensity method under the condition of low SNR at -20~10 dB. [ABSTRACT FROM AUTHOR]

Abstract—Numerical modeling with the use of mode theory was used to investigate the regularities of the spatial (depth and horizontal distance) distribution of the acoustic field intensity formed by multiple interaction of a caustic beam with a layered bottom in a shallow oceanic waveguide with an underwater sound channel open to the bottom. It has been established that at the values of the sound velocity at the upper boundary in the sedimentary layer, less than the sound velocity at the bottom in the water layer, the formation of a multi-beam structure of the acoustic field is possible. It was found that, starting from certain distances, newly formed beams can play the main role in the spatial distribution of the acoustic field intensity. [ABSTRACT FROM AUTHOR]

Precise control over the ultrasound field parameters experienced by biological samples during sonication experiments in vitro may be quite challenging. The main goal of this work was to outline an approach to construction of sonication test cells that would minimize the interaction between the test cells and ultrasound. Optimal dimensions of the test cell were determined through measurements conducted in a water sonication tank using 3D-printed test objects. The offset of local acoustic intensity variability inside the sonication test cell was set to value of ±50% of the reference value (i.e., local acoustic intensity measured at last axial maximum in the free-field condition). The cytotoxicity of several materials used for 3D printing was determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The sonication test cells were 3D printed from polylactic acid material, which was not toxic to the cells. Silicone membrane HT-6240, which was used to construct the bottom of the test cell, was found to reduce ultrasound energy minimally. Final ultrasound profiles inside the sonication test cells indicated the desired variability of local acoustic intensity. The cell viability in our sonication test cell was comparable to that of commercial culture plates with bottoms constructed with silicone membrane. An approach to construction of sonication test cells minimizing the interaction of the test cell and ultrasound has been outlined. [ABSTRACT FROM AUTHOR]

Bio-inspired geometries have many applications in engineering, including in the field of noise control. In this work, the aeroacoustic performance of a seal vibrissa shaped cylinder (SVSC) is investigated and compared to that of a circular cylinder at Re = 37 000. Experiments conducted in an anechoic wind tunnel are compared to results from a hybrid aeroacoustic simulation with excellent agreement observed between the two. The overall sound pressure level is found to be 24.3 dB lower for the SVSC, and no prominent narrowband component is observed in the acoustic spectrum. Analysis of the flow field and surface pressure fluctuations reveals that this is because the usual large-scale alternating vortex shedding realized for bluff body flows is absent for the SVSC. Instead, smaller uncorrelated vortices are shed from the upper and lower sides of the geometry, which, when combined with a lower spanwise correlation, results in a much lower acoustic intensity spread over a broader frequency range. [ABSTRACT FROM AUTHOR]

Vector acoustic properties of a narrowband acoustic field are observed as a function of range from a source towed in waters of depth 77 m on the New England Mud Patch. At the source frequency (43 Hz), the waveguide supported three trapped modes, with mode 2 weakly excited owing to the towed source depth. The receiving sensor was positioned 1.45 m above the seafloor with a sampling range aperture of 2500 m. The vector acoustics observations enabled study of vortex regions that encompass two singular points for active acoustic intensity: the vortex point, which is co-located with a dislocation, and stagnation point. Interpretative modeling, based on the normal modes and using a geoacoustic model consistent with those emerging from studies conducted at this location, is in agreement with these measurements. Model-data comparisons were based on the first-order variables of acoustic pressure and velocity along with inverse Hankel transforms, which yield normalized horizontal wavenumber spectra, and second-order variables in the form of horizontal and vertical intensity as well as non-dimensional intensity-based ratios. These measures provide a degree of observational confirmation of some vortex region properties. Both observations and modeling point to a gradual deepening of such regions with increasing range owing to sediment attenuation. [ABSTRACT FROM AUTHOR]

Single-beam acoustic tweezers have recently been demonstrated to be capable of selective three-dimensional trapping. This new contactless manipulation modality has great potential for many scientific applications. Its development as a scientific tool requires precise calibration of its radiation force, specifically its axial component. The lack of calibration for this force is mainly due to its weak magnitude compared to competing effects such as weight. We investigate an experimental method for the calibration of the axial stiffness of the radiation force by observing the axial oscillations of a trapped bead in a microgravity environment. The stiffness exhibits a linear relationship with the acoustic intensity and is of the mN/m order. Then, a predictive model, loaded with the experimental acoustic field, is compared to the measured stiffness with very good agreement, within a single amplitude coefficient. This study paves the way for the development of calibrated acoustic tweezers. [ABSTRACT FROM AUTHOR]

Objectives: To assess the ultrasonographic patterns of different calcium hydroxyapatite (CaHA) formulations, including the undiluted, diluted, and mixed with hyaluronic acid (HA) compounds. Methods: To review the ultrasonographic images of patients ≥18 years with confirmed injections of CaHA clinically and ultrasonographically, and without different concomitant types of fillers in the same region or other systemic or localized cutaneous diseases. Results: Twenty‐one patients met the criteria (90% female; 10% male; mean age: 52 years ± 12.8). Of these, 33.3% have been injected with an undiluted formulation, 33.3% with diluted, and 33.3% with a mixed formulation. All cases were studied with devices presenting frequencies that ranged from 18 to 24 MHz. Twelve cases (57%) were also studied with the 70 MHz. The ultrasonographic patterns of CaHA presented differences in the presence and intensity of PAS and the degree of inflammation according to the dilution and mix with HA. Diluted formulations show a milder intensity posterior acoustic shadowing (PAS) artifact than undiluted at 18–24 MHz. In mixed formulations, 57% showed mild PAS, and 43% demonstrated no PAS artifact at 18–24 MHz, besides fewer inflammatory changes in the periphery of the deposits. Conclusions: The ultrasonographic patterns of CaHA show differences in the presence and intensity of PAS and the degree of inflammation according to the dilution and mix with HA. Awareness of these ultrasonographic variations can support better discrimination of CaHA. [ABSTRACT FROM AUTHOR]