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At the early stages of drug development, the amount of drug materials is rather limited. In this case, viscosity measurement is often postponed to the later stages, where grams of proteins can be produced. Therefore, it is necessary to develop a viscometer capable of measuring the viscosity with high accuracy while requiring low sample volume. This study presents a novel viscosity measurement technique based on measuring the resonance frequency and motional resistance of a micropillar-enhanced acoustic wave (μPAW) device. The μPAW was developed by fabricating micropillars on the quartz crystal microbalance substrate in order to achieve ultra-high sensitivity, thanks to a unique coupling between the micropillar and the resonator. The experimental measurements demonstrated a nonlinear relationship between the density and viscosity of the fluid and the response of μPAW. A calibration correlation was developed using the response of μPAW in aqueous glycerol and sucrose solutions. The measurements were then extended using high-concentration BSA solutions as the model of protein solution. The main advantage of the μPAW device in this work over other viscometers is the ability to simultaneously measure solution viscosity and protein adsorption on the surface. This is a huge step forward in the development of sensing systems for the pharmaceutical industry, where real-time sensing of target biological proteins and measuring the viscosity of a solution is required. [ABSTRACT FROM AUTHOR]

This study investigates detonation propagation through a stoichiometric hydrogen-oxygen layer stratified above an inert gas, i.e., argon, with a diffuse interface at atmospheric pressure. A simple model capable of replicating the detonation inert gas diffuse layer interaction was developed that simulates previously conducted experiments. Detonation propagation is modeled by solving the two-dimensional reactive Euler equations for a calorically perfect gas with single-step Arrhenius chemistry. The acoustic impedance gradient associated with the argon diffusion into the hydrogen-oxygen results in a nonuniform initial density. Because of the perfect gas assumption, for a uniform initial pressure, as in the experiment, results in an initial temperature that is artificially nonuniform. The activation energy is adjusted for the imposed temperature nonuniformity in order to yield the correct ZND reaction zone length for the local argon dilution. Numerical soot foils are compared to experiments. Detonation propagation is possible due to the generation of triple points along the diffuse layer interface. These triple points, that generate new detonation cells, form from inflections in the reaction zones that develop because of the local increases in detonation strength. • Detonations in gravity layers are simulated and compared to experiments. • Simple chemistry with varying activation energy accounts for varying composition. • New detonation cells form from inflections on the shock over a few cell lengths. [ABSTRACT FROM AUTHOR]

• A time domain evaluation technique to validate the band structure is proposed. • The application of the localized radial basis function collocation method is extended. • The direct method is further applied to enhance the performance of the method. In this paper, the localized radial basis function collocation method is applied to investigate the in-plane elastic wave propagation of 2D phononic crystals. The direct method with local support domain in one line is used to enhance the stability of the localized radial basis function collocation method when dealing with the derivative calculations in the boundary and interface conditions. The Houbolt method is employed to discretize the time, and then the Fast Fourier Transform is adopted to obtain the band structure according to the wave vectors in the first Brillouin Zone. Different acoustic impedance ratios, filling rates, and lattice forms are studied. The numerical results can be used to validate the band structures obtained directly from the frequency domain. [ABSTRACT FROM AUTHOR]

• A stochastic vibro-acoustic analysis scheme is built based on the PUFEM/FEM and the direct probability integral method. • The new scheme can easily treat the propagation of uncertainties by summing the responses at each representative point. • The effects of uncertain acoustic impedance and modeling parameters on the system response are investigated. A novel stochastic response analysis scheme for 3D vibro-acoustic systems is constructed based on the PUFEM/FEM and the direct probability integral method, and the effect of uncertain acoustic impedance and modeling parameters on the system response is investigated. The proposed scheme has the capability of capturing waveform within the element, the small system matrices and easy handling acoustic impedance, also can efficiently treat the propagation of parameter uncertainties through transforming the integration of the response probability density function into the summation of the response under each representative point by partitioning the input probability space and smoothing the Dirac δ function. Numerical examples show that the mean and standard deviation of the responses computed by the proposed scheme agree well with the MCS, but the agreement of the standard deviation is slightly lower at the frequency with large response dispersion. The effect of uncertain acoustic impedance on the system response is mainly at the low frequencies, where the location and amplitude of resonance peaks fluctuate significantly. Uncertain modeling parameters synthetically modify the stiffness and mass matrix, altering the intrinsic properties and response of the system, and the response at the higher frequency is more sensitive to the uncertain modeling parameters. [ABSTRACT FROM AUTHOR]

In a multi-layered shielding material, the sequence of the arrangement of the layers affects the extent of insulation to acoustic waves. In the current work, hybrid composite laminates have been taken up comprising 10 sequences, employing metallic faceplate (AA6061), paperboard, ballistic-grade aramid, and ultra-high molecular weight polyethylene (UHMWPE) fabrics with an epoxy binder. In the theoretical studies, an analytical model for the transmission loss function has been developed by incorporating the multiple wave reflection principle in combination with interface-wise acoustic impedance grading. The analytical model has been validated using the transmission loss functions from numerical and experimental studies on the different sequences. The numerical simulation has been carried out using the harmonic acoustic analysis module, on Ansys R19.0. The experimentation has been carried out on an impedance tube. The results from the analytical model are in good agreement with the experimental and numerical simulation results, the analytical model can be used for predicting the transmission losses of composite laminates. [ABSTRACT FROM AUTHOR]

• Dynamic effective properties of piezoelectric composites with semi-spheroid inclusions are studied. • Volume average of the green's operators in the semi-spheroid domain are accomplished. • Non-reciprocal wave propagation characteristics in 3D piezoelectric composites are predicted. The non-reciprocal wave propagation characteristics of 3D random piezoelectric composites with aligned semi-spheroid inclusions are theoretically predicted. The self-consistent equations about the frequency-dependent effective properties are established, in which the volume average of dynamic Green's operators in semi-spheroid domain is involved. Due to the non-centrosymmetric inclusions, the composites macroscopically exhibit non-reciprocity, i.e. the effective properties, wave speed, acoustic impedance, attenuation and resonance frequency under the two waves of identical form but incident in opposite directions are different. The numerical results show that when the aspect ratio of the inclusion is large, the differences of the effective wave speed and impedance in two opposite directions are significant, which provides a possible means for modulation of wave propagation in the 3D random composites. [ABSTRACT FROM AUTHOR]

• A hybrid analytical method is built to study vibrations of the sandwich plate with z-direction reinforcements and cavities. • Both the sandwiches with hard and soft cores are considered in the analytical method that utilizes the layerwise model. • For the soft core sandwich, the layerwise model shows a much better accuracy than the existing equivalent single-layer model. • The accuracy of present method decreases at the high frequency since the homogenization of core neglects local vibrations. This paper presents a multi-functional sandwich plate with z-direction reinforcements and cavities that has the potential to meet the pressure resistance and the acoustic stealth requirement of the underwater equipment in deep sea. In order to predict its free and forced vibrations in both vacuum and water, a hybrid analytical method is proposed by combining a multi-level homogenization model and a layerwise model. The core with z-direction reinforcements and cavities is homogenized and effective elastic constants are calculated by the Mori-Tanaka formula. Vibration equations of the sandwich plate are derived utilizing the layerwise model based on the first-order shear deformation theory. The water effect is taken into account by the Euler's equation. Vibration results are solved under simply supported boundaries. Validation studies and parameter analyses are then conducted. It is found that different from the existing theoretical approach based on the equivalent single-layer model that is only applicable for the sandwich with a hard core material, the present hybrid analytical method is well suitable for vibration predictions of the sandwich plate with z-direction reinforcements and cavities, no matter the hard or soft core. Besides, due to the homogenization of the three-phase core and the neglecting of local vibrations in the layerwise model, the present analytical method only predicts accurate free vibrations when the half wave numbers are less than numbers of cavities in x and y directions, and also just shows the high precision in force vibration calculations as the maximum analysis frequency is less than the natural frequency of the mode corresponding to numbers of cavities. [ABSTRACT FROM AUTHOR]

A 0–3 piezoelectric ceramic-Portland cement (PC) composite with different compositions was fabricated and investigated with the following components: BZT (40, 50, and 60 vol% represented as BZT40, BZT60, and BZT60, respectively) and epoxy resin (0, 3, 5, and 7 vol% represented as ER0, ER3, ER5, and ER7, respectively). Experimental results show that increasing ER content (0–7 vol%) led to an increase in density (ρ c), for 50% BZT increased from 3.42 to 3.55 g/cm3 and a decrease in porosity, from 12.71 to 11.67% (for 50%BZT) and acoustic impedance (Z c) value increased from 9.67 to 8.84 × 106 kg/m·s2. Both ε r and tanδ decreased with increasing ER content. ER as the third phase resulted in a lower leakage current and the BZT60ER7 composite is found to have the lowest leakage current (20 μA). Increasing ER content led to a decrease in the piezoelectric charge coefficient (d 33). However, a notable increase in piezoelectric voltage coefficient (g 33) with increasing ER content up to 3 vol% was found. The optimization of both Z c and g 33 in this study can be observed in BZT50ER3 composite (Z c = 9.16 × 106 kg/m2·s and g 33 = 13.9 × 10−3 V m/N). In addition, the highest planar electromechanical coupling factor (k p = 17.97%) and thickness electromechanical coupling factor (k t = 17.75%) can be observed in BZT60ER7 composite. [ABSTRACT FROM AUTHOR]

In this study, a modified 1–3 piezoelectric composite was designed to investigate the relationship between its thickness and properties of piezoelectric composites. First, the modified 1–3 piezoelectric composite was simulated using COMSOL to obtain the resonant and anti-resonant frequencies of each piezoelectric composite thickness, and the electromechanical coupling coefficient, acoustic impedance, acoustic velocity, and frequency difference of the corresponding thickness were calculated. Second, the modified 1–3 piezoelectric composite was simplified using series-parallel theory and uniform field theory, and the relevant piezoelectric performance parameters of the piezoelectric composites of different thicknesses were calculated. The above results were verified experimentally, and the experimental results were in good agreement with the simulation results. Although the theoretical calculation results deviated slightly from the experimental results, the overall trend was consistent with the experimental results. Finally, the performance parameters of the modified 1–3 piezoelectric composite and traditional 1–3 piezoelectric composite with a thickness of 7.5 mm were compared. It was found that the acoustic impedance of this modified 1–3 piezoelectric composite was smaller than that of the traditional 1–3 piezoelectric composite, and the electromechanical coupling coefficient was larger than that of the traditional 1–3 piezoelectric composite. Therefore, this modified 1–3 piezoelectric composite has great potential for the preparation of high-performance piezoelectric ultrasonic transducers. [ABSTRACT FROM AUTHOR]

The prediction of cavitation damage through bubble collapse impact loads (BCIL) is essential, because it opens the opportunity to develop a phenomenological model that can be useful to improve the design process of hydraulic machinery components. Owing to the fast process and small-scale phenomena, direct measurement of the BCIL is greatly challenging if conducted through experimental methods. This study aims to reveal the underlying deformation process of solid materials under a single BCIL using a coupled multi-material hydrocode solver. Three different material constitutive models – purely elastic, elasto-plastic, and strain-hardening – were investigated through various types of metals and polymers. A detached single air bubble was placed near the solid surface inside a long and narrow tube. A planar shockwave was introduced to induce the bubble to collapse, resulting in BCIL that is high enough to cause plastic deformation on the solid surfaces. Measured BCILs from solid material cases show good agreement with the cavitation erosion test result of A1050, SS400, Epoxy resin, PP, and HDPE. These findings indicate that, in the case of metals, the deformation process can be inferred to acoustic impedance since impact energy evaluation shows no significant change when material plasticity is introduced. However, in the case of polymers, the deformation process is greatly influenced by yielding. [ABSTRACT FROM AUTHOR]

Acoustic properties of biomaterials and engineered tissues reflect their structure and cellularity. High-frequency ultrasound (US) can non-invasively characterize and monitor these properties with sub-millimetre resolution. We present an approach to estimate the speed of sound, acoustic impedance, and acoustic attenuation of cell-laden hydrogels that accounts for frequency-dependent effects of attenuation in coupling media, hydrogel thickness, and interfacial transmission/reflection coefficients of US waves, all of which can bias attenuation estimates. Cell-seeded fibrin hydrogel disks were raster-scanned using a 40 MHz US transducer. Thickness, speed of sound, acoustic impedance, and acoustic attenuation coefficients were determined from the difference in the time-of-flight and ratios of the magnitudes of US signals, interfacial transmission/reflection coefficients, and acoustic properties of the coupling media. With this approach, hydrogel thickness was accurately measured by US, with agreement to confocal microscopy (r2 = 0.97). Accurate thickness measurement enabled acoustic property measurements that were independent of hydrogel thickness, despite up to 60% reduction in thickness due to cell-mediated contraction. Notably, acoustic attenuation coefficients increased with increasing cell concentration (p < 0.001), reflecting hydrogel cellularity independent of contracted hydrogel thickness. This approach enables accurate measurement of the intrinsic acoustic properties of biomaterials and engineered tissues to provide new insights into their structure and cellularity. High-frequency ultrasound can measure the acoustic properties of engineered tissues non-invasively and non-destructively with µm-scale resolution. Acoustic properties, including acoustic attenuation, are related to intrinsic material properties, such as scatterer density. We developed an analytical approach to estimate the acoustic properties of cell-laden hydrogels that accounts for the frequency-dependent effects of attenuation in coupling media, the reflection/transmission of ultrasound waves at the coupling interfaces, and the dependency of measurements on hydrogel thickness. Despite up to 60% reduction in hydrogel thickness due to cell-mediated contraction, our approach enabled measurements of acoustic properties that were substantially independent of thickness. Acoustic attenuation increased significantly with increasing cell concentration (p < 0.001), demonstrating the ability of acoustic attenuation to reflect intrinsic physical properties of engineered tissues. [Display omitted] [ABSTRACT FROM AUTHOR]

An air-coupled acoustic matching layer, based on hollow glass microsphere composite, was developed for air-coupled ultrasonic transducers. The effects of the matrix, powder series, and volume fraction were systematically analyzed by acoustic and rheological characterization. The optimized hollow glass microsphere-epoxy composite showed a superior air-coupling performance, with a characteristics acoustic impedance of 1.08 MRayl and attenuation coefficient of 0.05 dB/mm, respectively. To validate the developed composite, an air-coupled ultrasonic transducer was fabricated with piezoelectric ceramic vibrator, and its feasibility for application in a gas flowmeter was demonstrated. The developed composite exhibits a suitable air-coupling performance for a high-accuracy ultrasonic gas flowmeter. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acoustic characteristics were determined for Glu in aqueous saccharide solution. • K s decrease with increasing concentration of both Glu and L-arabinose/D-xylose. • Glu acts as structure maker in the presence of saccharides. • Saccharide strengthens the H-bonded network of water by Glu, as per FTIR study. Glutamic acid is a non-essential amino acid, meaning that the body can synthesize it on its own, and it doesn't necessarily need to be obtained from the diet. Using an ultrasonic interferometer, the ultrasonic velocity at 293.15 K and 298.15 K and at experimental pressure P = 101 kPa were determined in order to evaluate and comprehend the synergy between non-essential amino acid and saccharides (L-arabinose/D-xylose) in an aqueous system. There is a direct correlation between the weak and strong molecular interactions that occur between the solution's constituents and the propagation of ultrasonic sound waves through the experimental solutions. Using the ultrasonic velocity data, isentropic compressibility (K s) apparent molar isentropic compressibility (K s , ϕ ) and isothermal compressibility (K T) were calculated. In addition to these characteristics, acoustic impedance (Z), internal pressure (π i), relative association (R A), molar free volume (V f), molar free length (L f) and surface tension (γ) were deduced and analysed to advocates potent ion- solvent interactions. In order to gain understanding of Glu-Glu and Glu- L-arabinose/D-xylose interactions in aqueous medium, these parameters were interpreted. Ion-solvent interactions are stronger than ion-ion interactions due to the greater and positive values of K s 0. Strong contacts occur between the polar segments of L-arabinose/D-xylose and the zwitterionic groups of Glu, and these interactions become stronger as the concentration of L-arabinose/D-xylose increases, as indicated by positive values of K s , ϕ , t r 0. The water structure is reformed during the solvation and ion association processes of Glu. Furthermore, the spectroscopic investigation has been conducted using the FTIR technique in order to verify the results obtained from acoustic studies. Predominant ion-hydrophilic/hydrophobic interactions prevail in the studied system is validated by FTIR study. Absorption band widening indicates that intermolecular hydrogen bonding predominates over intramolecular hydrogen bonding. [ABSTRACT FROM AUTHOR]

The paper analyzes the propagation law of stress waves in CFRP unidirectional plate specimens and adhesive plate specimens under laser shock conditions using a combination of experimentation and simulation. The finite element model is corrected by using the back particle velocity curve obtained from the experiment. Subsequently, the spatiotemporal stress distribution is extracted from the finite element model. The results indicate an overall attenuation trend of the stress wave propagating in the unidirectional plate. In the adhesive plate, the peak value of the stress wave increases first at the adhesive layer position due to the acoustic impedance mismatch and energy absorption characteristics of the adhesive layer material and CFRP. Then it tends to increase after decay. Moreover, the behavior characteristics of the stress wave differ significantly when it propagates from high-impedance material to low-impedance material compared to when it propagates from low-impedance material to high-impedance material. • Conduct an experiment on laser shock for carbon fiber plate and bonded plates. • Finite element models were validated for both unidirectional and bonded plates. • The propagation law of stress waves in bonded joints. • Differences in stress wave propagation in materials with varying acoustic impedances. [ABSTRACT FROM AUTHOR]

The primary aim of this research is to enhance seismic data interpretation and CO 2 monitoring by utilizing seismic inversion techniques based on the simulated annealing method. Simulated annealing is a global optimization technique employed for inverting seismic data and provides better results as compared with local optimization-based inversion. This methodology is implemented in the Utsira Formation, located at a depth of 1000 m within the Sleipner Field, Norway. The study encompasses the analysis of three sets of time-lapse seismic data, first from 1994 (pre-injection), followed by surveys in 1999 and 2001, corresponding to the injection of 2.35 million tonnes and 4.26 million tonnes of CO 2 , respectively. Firstly, synthetic data is used to check the reliability of the algorithm followed by real data application. This process starts by performing the inversion analysis on the synthetic data which shows a decrease in the impedance values observed at the injection site whereas the seismic amplitude increases. The qualitative as well as quantitative analysis depicts that the algorithm works satisfactorily. The same process is applied to the real data from the Sleipner field. Acoustic impedances are calculated using a simulated annealing-based inversion scheme for the pre-injection case in 1994 and post-injection scenarios in 1999 and 2001. Because of the presence of injected CO 2 in the years 1999 and 2001, a low impedance zone that ranged from 2000 m/s*g/cc to 2400 m/s*g/cc appeared at the time interval of 0.85–1.10sec. The interpretation of the inverted impedance section and seismic attribute analysis show no signature of CO 2 leakage. The results indicated that the inverted section which is derived from the SA optimization technique shows very clear CO 2 information offering a more realistic representation with enhanced resolution of the CO 2 plume and its migratory paths. • The study developed a methodology for enhanced CO 2 monitoring of time-lapse seismic data. • The methodology uses seismic inversion based on simulated annealing, and compared with traditional methods. • The developed method provides very high-resolution subsurface information and hence CO2 movement. • Finally, the methodology is applied to the Sleipner data and CO 2 leakage has been detected with a very high confidence level. [ABSTRACT FROM AUTHOR]

Over 20 million tons of CO 2 ‌ have been injected into the sandy Utsira formation of the Sleipner field in the North Sea basin. The thin layering of sands, CO 2 -saturated sands, and intra-formation thin shales cause interference effects in the seismic response of the monitor surveys. Initial analysis of the amplitude change suggests over 60 % change in the relative acoustic impedance of the reservoir between the 1996 and 2010 surveys. This study follows a multi-stage inversion scheme applied to time-lapse seismic monitoring of the Sleipner field. At each stage, the errors and uncertainties caused by noise and tuning are deeply analyzed. Time-shift estimation from seismic data shows spurious features caused by tuning, specifically using the window-based methods. The time-strain inversion builds a low-frequency initial model for the subsequent model-based inversion but is contaminated by remnants of noise and interference. The synthetic wedge modelling and analysis provides the origins and severity of the tuning error in time-shift and time-strain estimations at the Sleipner field. The model-based inversion removes noise and injects high-frequency components into the results, improving the outcome of time-strain inversion. However, it fails to fully eliminate the tuning imprints and leaves strong traces of error on the results. Afterward, the time-lapse Bayesian seismic inversion slightly adjusts the outcome and shows how deep the influence of interference effect on the time-lapse inversion is. In addition, the complementary discussion on rock physical models in estimating the saturation changes highlights how the tuning error can lead to flawed quantitative interpretation. [ABSTRACT FROM AUTHOR]

Characterization of fracture networks is essential in the production optimization or storage calculation for enhanced geothermal systems or geologic carbon storage. A novel inversion approach is proposed for estimating the fracture networks in this research. The discrete fracture network technique is adopted to probabilistically describe various fracture parameters such as trace length, midpoint position or azimuthal angle. The reversible jump Markov chain Monte Carlo algorithm is applied to explore the target posterior distribution of model parameters of differing dimensionality, in which the number of fractures is assumed to be unknown. More specifically, the birth-death strategy is utilized to perturb the fracture number iteratively in the sampling process. The proposed methodology is applied with two different types of observational datasets, namely the head records from steady-state flow simulation and the acoustic impedance obtained from seismic inversion. The sampling results can successfully recover the fracture geometry in the observed domain, and the number of fractures in the system can be retrieved as well. Benchmarked on multiple Markov chain trials, the technique of parallel tempering can greatly improve the convergence efficiency and increase the diversity of sampled posterior models, through the random swapping of model states across the whole temperature ladder. • Fracture networks in the subsurface are inverted stochastically based on different observational datasets. • The rjMCMC algorithm is applied to sample the posterior distribution of model parameters of differing dimensionality. • Parallel tempering is implemented to improve the convergence efficiency and increase the diversity of sampled models. [ABSTRACT FROM AUTHOR]

The stress wave attenuation in five types of chocolate (extra dark, dark, milk, white, and ruby) was studied. The main acoustics properties of these chocolates were described in terms of longitudinal and transversal wave velocities. The attenuation of the stress waves was studied using the experimental technique known as the Split Hopkinson Pressure Bar (SHPB). The SHPB set-up consists of a specimen and linear elastic incident and transmission bar. Experimental data have been evaluated both in the time as well as frequency domain. Attenuation of the stress wave was described namely using the frequency dependence of the transmission coefficient of the stress wave. This damping increases with the plastic strain of the tested chocolate specimens. From a technological point of view, the fat content of the chocolate has the highest influence on the reduction of the longitudinal wave propagation velocity. The lowest attenuation was observed for the dark chocolate. • Five types of chocolate - extra dark, dark, milk, white, and even ruby, which is poor described in literature, were tested. • Use of the specimens of different length enabled to describe the stress pulse attenuation during their propagation. • Highest attenuation was observed for the extra dark and ruby chocolates. The lowest one was found for the dark chocolate. • Stress wave attenuation has been described both in the time and frequency domain. • SHPB can reflects the effect of chocolate processing, composition, and particle size distribution on the mechanical behaviour. [ABSTRACT FROM AUTHOR]

The accuracy of sea-level rise predictions is highly dependent on reliably understanding the subglacial environment beneath ice streams. Bedforms result from the interaction between ice and its substrate, and therefore have the potential to shed light on poorly understood basal conditions influencing ice dynamics. However, theoretical models of bedform formation are often based on observations from deglaciated areas or from sparsely-sampled geophysical surveys over glaciated regions. Here, we use high-resolution three- and two-dimensional radar and seismic data to reveal details of the initiation and evolution of a subglacial bedform beneath Rutford Ice Stream, West Antarctica. Radar surveys at 20 m and 50 m line spacing allow detailed imaging of bed topography, including a moat up to 55 m deep, surrounding the upstream end of a 50-m high and >18-km long bedform. Many models rely on either a topographical or a locally resistant seed point to initiate bedform formation. The bedform described here is mostly composed of soft sediment (porosity >0.3) and lacks a boulder or outcrop, suggesting the bedform initiated without a topographic seed point. Sediment at the upstream end of bedforms appears stiffer over a distance of 2.3 km. We suggest sediment inhomogeneities in the initially flat bed cause the deposition of sediment, which, assuming resistant enough, acts as a seed point for bedform extension and moat erosion. The moat's geometry and its truncation of other bedforms suggest that it was eroded after the deposition of surrounding bedforms. These observations from a modern ice stream deliver information of subglacial processes involved in the initiation as well as in situ high-resolution topography and properties of bedforms and moats. Using these observations numerical models can be tested and developed accordingly. • Evidence for a bedform initiating without pre-existing topographic perturbations. • A moat around an elongated bedform revealed from high-resolution radar data. • Constraints of bedform formation mechanism from a modern ice stream. [ABSTRACT FROM AUTHOR]

Microultrasound (μUS) linear arrays operating at frequencies over 25 MHz have applications in high resolution biomedical imaging. 1–3 connectively piezoceramic – polymer composite ("piezocomposite") material is attractive for fabrication of these devices due to its high effective electromechanical coupling coefficient and low acoustic impedance for better acoustic matching between transducer and tissue. However, a major concern with this type of material comes from interference between the fundamental thickness-mode resonance and spurious modes, which is usually generated by wave propagation and reflection within the repetitive and symmetrical structure of classical piezocomposite. In general, a fine spatial scale is required of the material structure to suppress the spurious modes; however, the fabrication process is challenging using standard dice-and-fill methods at the fine scales required for high frequencies. A promising way to overcome this challenge is to manipulate the lateral geometry and spacing of the piezoceramic pillars with a random distribution. In this work, gel casting in association with a micromoulding technique has been developed for manufacturing 1–3 randomised piezocomposite active material for μUS linear arrays. 48 vol% solid loading of piezoceramic powder with 30 wt% Hydantoin resin content was employed to prepare a low viscosity aqueous suspension. Through varying powder size, it was found that the suspension with 1.22 µm powder had the highest viscosity, ~ 0.47 Pa.s, and a short gelation time, ~ 10 mins. However, all suspensions had viscosities less than 1 Pa.s at a shear rate of 100 s−1, indicating that they had good flowability. The green body samples showed mean flexural strength 49.7 ± 2.49 MPa. After piezocomposite fabrication with randomised pillars, surface planarisation was used to obtain reliable edge definition of photolithographically-defined electrodes. 20-element arrays with 50-μm element pitch were configured using a bilayer lift-off process. The 1–3 randomised piezocomposite demonstrated its capability to minimise the effects of spurious modes in the thickness mode frequency range, while the thickness resonances provided k 33 = 0.67. Without a matching layer, the array produced a − 6 dB bandwidth of 38.4%- and − 20-dB pulse length of 0.26 μs. These results show that 1–3 randomised piezocomposite fabricated from gel-casting associated with a micromoulding technique is feasible for fabrication of μUS linear arrays and may offer a route to small wafer-scale production. • Particle size distribution influences rheological behaviour and gelation time. • Gel casting solves the difficulties in complex shape and micro-scale fabrication and provides homogenous microstructure. • 1–3 randomised piezocomposite demonstrates its capability to minimise spurious modes. • Randomised piezocomposite fabricated from gel-casting offers feasibility of wafer-scale fabrication for μUS linear arrays. [ABSTRACT FROM AUTHOR]

Acoustic emission (AE) detection through a liquid medium is a simple and effective method that can be widely applied to AE diagnosis for rotating machinery. As AE diagnosis is performed by correlating the signal intensity with the failure level and the frequency characteristics with the failure type, it is important to clarify the propagation characteristics of AE waves in liquid media to enable accurate AE diagnosis using a simpler system that utilizes AE propagation in a liquid medium. Therefore, in this study, systematic experiments were conducted focusing on the liquid medium type and the propagation distance as factors affecting the propagation characteristics of AE waves. As the area where AE waves propagate, we mainly focused on the near-field, where AE waves do not spread and are not attenuated with the propagation distance. First, we investigated the propagation and attenuation characteristics of AE waves in the near-field using an artificial AE source in liquid media such as purified water, cutting fluid solution, and lubricating oil. Differences in attenuation characteristics with the liquid medium were observed. Moreover, the propagation distance affected the attenuation characteristics, i.e., the signal intensity decreased with increasing propagation distance in a manner depending on the viscosity of the liquid medium, especially in the frequency bandwidth range from 1.5 to 3.0 MHz. Second, we theoretically verified some of the experimental results from the viewpoint of ultrasonic propagation in a liquid medium. As a result, the observed differences in attenuation characteristics with liquid medium were explained by the acoustic impedances of the liquid media, and the attenuation of the signal intensity of AE waves with increasing propagation distance was caused by the increasing absorption coefficient with increasing viscosity of the liquid medium. • Evaluation of propagation characteristics of acoustic emission waves propagating in liquid media. • Propagation distance and liquid medium type affect propagation characteristics. • Viscosity of the liquid medium affect the signal intensity of acoustic emission waves above 1.5 MHz. [ABSTRACT FROM AUTHOR]

The aim of this research was to explore the interaction between ultrasound-activated microbubbles (MBs) and Pseudomonas aeruginosa biofilms, specifically the effects of MB concentration, ultrasound exposure and substrate properties on bactericidal efficacy. Biofilms were grown using a Centre for Disease Control (CDC) bioreactor on polypropylene or stainless-steel coupons as acoustic analogues for soft and hard tissue, respectively. Biofilms were treated with different concentrations of phospholipid-shelled MBs (107-108 MB/mL), a sub-inhibitory concentration of gentamicin (4 µg/mL) and 1-MHz ultrasound with a continuous or pulsed (100-kHz pulse repetition frequency, 25% duty cycle, 0.5-MPa peak-to-peak pressure) wave. The effect of repeated ultrasound exposure with intervals of either 15- or 60-min was also investigated. With polypropylene coupons, the greatest bactericidal effect was achieved with 2 × 5 min of pulsed ultrasound separated by 60 min and a microbubble concentration of 5 × 107 MBs/mL. A 0.76 log (83%) additional reduction in the number of bacteria was achieved compared with the use of an antibiotic alone. With stainless-steel coupons, a 67% (0.46 log) reduction was obtained under the same exposure conditions, possibly due to enhancement of a standing wave field which inhibited MB penetration in the biofilm. These findings demonstrate the importance of treatment parameter selection in antimicrobial applications of MBs and ultrasound in different tissue environments. [ABSTRACT FROM AUTHOR]

Composite materials can be promising to decouple electron and phonon transport for improved thermoelectric properties. Herein, the synergistic effect of the particle size of the dispersed phase and the interface thermal resistance (R int) between the phases on the phonon thermal conductivity (κ ph) of the (1- x)La 0.95 Sr 0.05 Co 0.95 Mn 0.05 O 3 /(x)WC thermoelectric composite is demonstrated. The embedded WC, owing to its high electrical conductivity (σ), does improve σ of the composite. A high acoustic impedance mismatch between the phases results in a large R int and lowers κ ph. Change in κ ph is further explained using theoretical analysis of Bruggeman asymmetrical model. The correlation between R int and Kapitza radius is discussed to analyze the reduced κ ph. Synergistic effect of improved σ and lowered κ ph result in improved thermoelectric figure of merit (zT) of 0.20 at 463 K for (1- x)La 0.95 Sr 0.05 Co 0.95 Mn 0.05 O 3 /(x)WC composite. This study shows promise to design thermoelectric composites with the desired κ ph considering the elastic properties between the phases. [Display omitted] [ABSTRACT FROM AUTHOR]

The electrical properties of C/SiC composites could be used for online and in-situ damage monitoring. To investigate alternating current (AC) impedance response to damage in the C/SiC composites, monotonic and incremental cyclic tensile tests were performed. Both AC impedance and acoustic emission (AE) techniques were applied to clarify the damage evolution during the tests. The relationship between damage and electrical impedance response was investigated and validated via macroscopic equivalent circuit models. The effects of longitudinal deformation and damage on AC impedance characteristics, including impedance magnitude and phase angle, were obtained from the models. Results showed that the longitudinal deformation increases the impedance magnitude and the phase angle, and the damage causes the impedance magnitude to increase and the phase angle to decrease. The phase angle is significantly sensitive to fiber breakage, which makes the AC-based method more suitable for online damage monitoring and final failure warning. [ABSTRACT FROM AUTHOR]

• Artifact of blood flow velocity • String-like mobile echodensities (SLMEs) • Acoustic impedance (AI) String-like mobile echodensities (SLMEs) are sometimes found on postoperative duplex ultrasound (DUS) performed after carotid endarterectomy (CEA); however, they may not be visible on intraoperative DUS. The reasons for these echo findings and associated clinical course remain unknown. Routine postoperative DUS evaluation after CEA was retrospectively examined in 101 consecutive patients (107 lesions) who underwent CEA between April 2015 and December 2021, at our institution. Ten SLMEs were identified in eight patients. All SLMEs were 1–3 mm long, mobile, and extended straight from the intima-media complex of the wall of the common carotid artery or carotid bulb. Most lesions resolved spontaneously; a few lesions were observed repeatedly, albeit not causing cerebral infarction or transient ischemic attacks. SLMEs can be observed in a small percentage of patients after CEA, and they do not seem to be of clinical significance. [ABSTRACT FROM AUTHOR]

Ultrasound facilitates the penetration of macromolecular compounds through the skin and offers a promising non-invasive technique for transdermal delivery. However, technical difficulties in quantifying ultrasound-related parameters have restricted further analysis of the sonophoresis mechanism. In this study, we devise a bolt-clamped Langevin transducer-based sonophoresis device that enables us to measure with a thin lead zirconate titanate (PZT) sensor. One-dimensional acoustic theory accounting for wave interaction at the skin interface indicates that the acoustic pressure and cavitation onset on the skin during sonophoresis are sensitive to the subcutaneous support, meaning that there is a strong need to perform the pressure measurement in an experimental environment replacing the human body. From a series of the experiments with our new device, the transdermal penetration of polystyrene, silica and gold nanoparticles is found to depend on the size and material of the particles, as well as the hardness of the subcutaneous support material. We speculate from the acoustic pressure measurement that the particles' penetration results from the mechanical action of cavitation. [ABSTRACT FROM AUTHOR]

• Skull sound speed model was constructed using the deep-learning-based surface extraction method. • Fast wave traveltime computation and phase aberration correction were achieved by using the ray theory. • The proposed method was evaluated using skull phantom for both transcranial plane wave imaging and ultrafast Doppler imaging. Ultrafast ultrasound Doppler imaging facilitates the assessment of cerebral hemodynamics with high spatio-temporal resolution. However, the significant acoustic impedance mismatch between the skull and soft tissue results in phase aberrations, which can compromise the quality of transcranial imaging and introduce biases in velocity and direction quantification of blood flow. This paper proposed an aberration correction method that combines deep learning-based skull sound speed modelling with ray theory to realize transcranial plane-wave imaging and ultrafast Doppler imaging. The method was validated through phantom experiments using a linear array with a center frequency of 6.25 MHz, 128 elements, and a pitch of 0.3 mm. The results demonstrated an improvement in the imaging quality of intracranial targets when using the proposed method. After aberration correction, the average locating deviation decreased from 1.40 mm to 0.27 mm in the axial direction, from 0.50 mm to 0.20 mm in the lateral direction, and the average full-width-at-half-maximum (FWHM) decreased from 1.37 mm to 0.97 mm for point scatterers. For circular inclusions, the average contrast-to-noise ratio (CNR) improved from 8.1 dB to 11.0 dB, and the average eccentricity decreased from 0.36 to 0.26. Furthermore, the proposed method was applied to transcranial ultrafast Doppler flow imaging. The results showed a significant improvement in accuracy and quality for blood Doppler flow imaging. The results in the absence of the skull were considered as the reference, and the average normalized root-mean-square errors of the axial velocity component on the five selected axial profiles were reduced from 17.67% to 8.02% after the correction. [ABSTRACT FROM AUTHOR]

This study investigates acoustic impedance matching between a thermoacoustic Stirling heat engine and a branch liquid column, using multiple regenerators. We characterize acoustic impedances at both the engine and liquid column load ends using thermoacoustic theory, expressed as functions of frequency and temperature differences across regenerators. The intersection points of these functions indicate matched impedances, critical for evaluating the engine's operating points. Notably, this study emphasizes the impact of a vibrating membrane on the system's acoustic impedance, highlighting its significant role in modulating acoustic states and facilitating self-sustained oscillations. To verify our theoretical models, we conducted experiments with the proposed fluidyne engine under various liquid column volumes. The verifications confirmed our simple calibrations for characterizing a vibrating membrane clamped in the engine and the oscillating liquid columns. Significantly, the acoustic compliance and inertance effects respectively introduced by the membrane and liquid columns enable us to modulate the engine's acoustic states. The proposed configuration is named a thermoacoustic Stirling fluidyne. This fluidyne, a heat engine that outputs work power using a liquid piston, achieves a markedly higher acoustic impedance than the pure gas case while maintaining traveling wave phasing for the regenerators. • Introducing a flexible design in the fluidyne-style thermoacoustic Stirling engine. • Utilization of a vibrating membrane coupled with oscillating liquid columns for improved acoustic modulation. • Attainment of remarkably high acoustic impedance, while efficiently preserving the traveling wave phasing within regenerators. [ABSTRACT FROM AUTHOR]

• Realize an acoustic comb filter by a shunted-electromechanical-diaphragm. • Tailor sound absorption/transmission peaks number at will by circuit tuning. • Tailor sound absorption/transmission peaks frequencies at will by circuit tuning. • Remove geometrical and mechanical constrains for acoustic resonance design. • Bypass acoustic sum rules to allow control noise in a much broader bandwidth. A noise with multiple tonal components is prevalent in practice, and these tones, contributing to noise annoyance, may even span several octaves and the frequencies of them always vary with working condition. Conventional broadband noise control structures with limited spaces are hard to address multiple-tonal noise due to sum rules in acoustics. Resonator arrays is feasible but their dependency on the geometrical and mechanical parameters challenges matching variable frequencies of tonal components. This work introduces a Shunt-Electromechanical Diaphragm (SEMD) to construct sound absorption and transmission spectra with multiple peaks, thereby creating an acoustic comb filter in deep-sub-wavelength scale to address multiple-tonal noise. The SEMD consists of a moving-coil loudspeaker integrated with a circuit housing multiple resonance branches, whose acoustic impedance is determined by circuit parameters. This allows the frequencies and number of sound absorption and transmission peaks to be arbitrarily reconfigured by adjusting circuit parameters. A comprehensive lumped parameter model is devised to elaborate on the electromechanical coupling of the SEMD and predicts its comb filter effect. Experiments in an impedance tube show that comb spectra with three peaks for sound absorption and transmission are successfully constructed and reconfigured by collocating circuit parameters, verifying the theoretical model. The three peaks of the sound absorption spectrum have values above 0.9 and are electrically tunable over more than three octaves. The method in this work blends electromechanical dynamics with specialized analog circuits for efficient tonal noise reduction across a broad bandwidth, which removes the geometrical and mechanical constrains and paves the way for digital reconfigurable acoustic devices. Moreover, the multiple peaks matching between noise source and sound absorption/transmission spectra via the electromechanical coupling mechanism of the SEMD bypasses the sum rules in acoustics, providing an alternative method for controlling noise over a much broader bandwidth. [Display omitted] [ABSTRACT FROM AUTHOR]

Although cardiovascular diseases are the leading cause of death globally, un-stable atherosclerotic plaques play a vital role in plaque disruption which are related with multiple cardiovascular complications, but non-invasive and in-expensive diagnostic tools for the identification of associated unstable atheroscle-rotic plaques are not yet available. Scanning acoustic microscopy offers a high potential to fill this critical gap in patient care. However, convincing validation and calibration of this technique requires high-resolution maps of calcium concentrations of atherosclerotic plaques. In this preliminary study, a highly significant (p = 0.008) correlation between the median Ca concentra-tions and acoustic impedance values is displayed with a correlation coefficient of 0.96. Besides, we suggest that synchrotron radiation-based X-ray fluores-cence imaging with micrometer spatial resolution can provide such a gold standard for the calibration of scanning acoustic microscopy. Calibration of scanning acoustic microscopy for the differentiation between unstable and stable atherosclerotic plaques by X-ray flu- orescence imaging. [Display omitted] • Differentiation of unstable plaques with X-ray Fluorescence Microscopy. • Acoustic impedance mapping with Scanning Acoustic Microscopy. • Correlation between Acoustic Impedance and Ca Concentrations. [ABSTRACT FROM AUTHOR]

The size and distribution of the contact stress at the assembly interface will directly affect the connection performance of the mechanical joint. However, the rough assembly interface presents strong dielectric discontinuity and material nonlinearity, which become the bottleneck restricting the development of contact stress detection. How to obtain contact stress by nondestructive testing means has become an urgent problem to be solved. In this paper, a multi-layer interface contact stress detection method based on contact acoustic resistance model is proposed to solve the difficult problem of rough interface contact stress detection. Firstly, based on the formation mechanism of contact acoustic resistance of rough assembly interface, the equivalent contact acoustic resistance expression of contact layer is derived. Secondly, the contact mechanism of rough assembly interface is clarified, and the mapping relationship model between contact acoustic resistance and contact stress is constructed. On this basis, according to the transmission law of ultrasonic wave at different interfaces of multilayer acoustic impedance, the expression of acoustic transmission coefficient at the interface of variable acoustic impedance is obtained. A contact stress detection method based on contact stress-contact acoustic resistance coefficient and acoustic transmission coefficient is proposed. The correctness of the theoretical model is verified by the tensile testing machine, and the maximum error is 15.52 %. This method will provide powerful data support for the evaluation of assembly interface connection state. [ABSTRACT FROM AUTHOR]

In this work, it is proposed a novel customized-accuracy simultaneous sensing of temperature, pressure and acoustic impedance based on forward Brillouin scattering (FBS) in optical fiber. By observing the variations in frequency shift-temperature, frequency shift-pressure and frequency shift-acoustic impedance for different radial acoustic modes in certain types of fibers, we propose a novel method for simultaneously measuring three parameters (temperature, pressure and acoustic impedance) using the changes of frequency shift of three FBS scattering peaks. It is very interesting that we can utilize numerous sensitivity combinations of three measured parameters corresponding to different frequency shifts in optical fibers, allowing for the selection of different combinations of measurement accuracy for temperature, pressure and acoustic impedance sensing, and thus meeting the different requirements for measurement accuracy in specific measurement applications. In a proof-of-concept experiment, a 1060-XP fiber is used as the sensing fiber. By choosing suitable sensitivity combinations of coefficients of frequency shift-temperature, frequency shift-pressure and frequency shift-acoustic impedance of the fiber, we achieve high-accuracy simultaneous measurement of temperature, pressure and acoustic impedance with low measurement uncertainties of 0.13 °C, 0.04 MPa and 0.006 MRayl, respectively. The proposed method not only realize temperature, pressure and acoustic impedance simultaneous sensing for the first time, but also open up a new way of fiber optic sensing with customized multi-parameter sensing accuracy. [ABSTRACT FROM AUTHOR]

• Excavated, partially, and fully contained explosions are modelled at centrifuge. • Ground surface deformation in diverse explosion events are assessed. • Blast wave propagation induced by buried explosion in sand is analysed. • Scaling laws for ground shock attenuation are examined and calibrated. A series of centrifuge model tests of buried explosions in dry sand were designed and performed to investigate the blast effects in diverse underground explosion (UE) scenarios. The typical ground deformation pattern and blast wave propagation in different types of UE events were modelled. The excavated cratering was observed in shallow-buried excavation explosion tests. Surface collapse and subsidence craters were formed in the partially contained explosion tests, in which the initial ground motion direction turned from upward to downward with the increase of burial depth. The scaling law for centrifuge modelling of blast wave propagation was derived and examined. The critical burial depth for complete coupling of ground shock energy is within the range of 0.4 m/kg1/3 and 0.8 m/kg1/3, and the gravity effect on blast wave propagation can be disregarded under centrifugal accelerations of 62 g and 106 g (g is the Earth's gravity). The elastic blast wave velocity in dry sand was determined in the model test, and it increased with the burial depth. The attenuation laws for peak pressure and peak scaled acceleration in dry sand were calibrated, and the scaling coefficient for peak pressure estimation increased with the medium's acoustic impedance, while the attenuation coefficient showed a contrasting trend. [ABSTRACT FROM AUTHOR]

The simultaneous prediction of the subsurface distribution of facies and acoustic impedance (I P) from fullstack seismic data requires solving an inverse problem and is fundamental in natural resources exploration, carbon capture and storage, and environmental risk management. In recent years, deep generative models (DGM), such as variational autoencoders (VAE) and generative adversarial networks (GAN), were proposed to reproduce complex facies patterns honoring prior geological information. Variational Bayesian inference using inverse autoregressive flows (IAF) can be performed to infer the solution to a geophysical inverse problem from the encoded latent space of such pre-trained DGM. Successful applications of such approach on crosshole ground-penetrating radar synthetic data inversion demonstrated that the technique's accuracy is comparable to that of Markov chain Monte Carlo (MCMC) inference methods, while significantly reducing the computational cost. Nonetheless, these application examples did not account for the spatial uncertainty affecting the facies-dependent continuous physical property, from which the geophysical data are calculated. This uncertainty can significantly affect the inversion accuracy and its applicability to real data. In this work, specific VAE and GAN architectures are proposed to simultaneously predict facies and co-located I P , while accounting for their spatial uncertainties. The two types of generative networks are used in Bayesian inversion with IAF for the inversion of seismic data. The results are found to reproduce the statistics of the training images and solve the seismic inversion problem accurately, comparably to MCMC inversion. Furthermore, advantages and limitations of the two DGMs are evaluated by comparing the results obtained. • We propose a VAE and a GAN for multivariate modeling honoring of facies and co-located acoustic impedance. • Resulting realizations honor geological prior and assumed spatial statistics. • We improve uncertainty quantification in variational Bayesian inference using VAE and GAN. • The generative networks are combined with inverse autoregressive flows for fullstack seismic data inversion. • We obtain improvements in subsurface reconstruction and uncertainty quantification. [ABSTRACT FROM AUTHOR]

To date, cavitation erosion of carbon fibre reinforced polymer (CFRP) composites has attracted only limited scientific attention. This paper investigates this knowledge gap through a series of experiments, in which unidirectional and bidirectional (2x2 twill) CFRP composites were exposed to cavitation clouds produced by an ultrasonic transducer in distilled water. Both composites were bonded with epoxy resin. Cavitation erosion tests were conducted according to the ASTM G32-16 standard using a stationary specimen method. The effect of water absorption on monitoring erosion damage was studied using saturated and dry specimens. Specimen mass loss measurements and microscopy observations were done at regular intervals throughout testing. Erosion imprint topographies were studied using X-ray computed microtomography. Three distinct erosion stages were identified from the erosion process observations. Nonuniformities in surface geometry and properties facilitated nucleation and accelerated local erosion. Surface epoxy thickness, fibre diameter and packing, and thickness and layup of fibre bundles influenced the erosion process. The erosion mechanisms included cracking and debonding of epoxy, and tunnelling and trenching in fibre bundles. Research findings indicated that the composite internal structure can potentially be designed for reduced water absorption and increased erosion resistance. Acoustic impedance was most efficient in predicting material response to cavitation erosion. • Surface nonuniformities in geometry and properties cause erosion localisation. • Fibre diameter and packing dominated CFRP composite response to cavitation erosion. • Maximum erosion depth in composites is much greater than the mean erosion depth. • Composite Internal structure can be designed for higher erosion resistance. • Ultrasonic field accelerated the initial water absorption of CFRP composites. [ABSTRACT FROM AUTHOR]

Hafnium Oxynitride belongs to the group IVB compounds with high permittivity and large acoustic impedance. In this work, hafnium oxynitride films have been synthesized using plasma-enhanced atomic layer deposition on Si and Quartz substrates. XRD results show the presence of mixed cubic and monoclinic phases with an optimum crystallization occurring at 850 °C. The thin films show strong absorption in the UV–visible spectrum suggesting semiconductor behaviour. The optical properties of the spectrophotometer and spectroscopic ellipsometry agree with the XRD observations. We also report the first observation of experimentally derived photoluminescence (PL) from hafnium oxynitride thin films synthesized using plasma-enhanced atomic layer deposition. The PL spectrum is consistent with the XRD results with two absorption peaks around 576 nm and 705 nm, corresponding to cubic and monoclinic phases, respectively. Also, the PL results match very well with the theoretical value of the band gap of cubic and monoclinic phases of Hf 2 ON 2. The Raman spectrum shows a phonon band gap around 242–263 cm−1, consistent with the theoretically reported value for cubic Hf 2 ON 2. [Display omitted] • The as-deposited films of hafnium oxynitride were partially annealed because of N 2 plasma exposure for 15 s. • XRD and Photoluminescence spectra suggested the presence of mixed phases: cubic and monoclinic. • The electronic and phononic band gap matched very closely with the theoretical band gaps of cubic and monoclinic Hf 2 ON 2. • XPS data suggested the chemical states of Hf, N, O to be of Hf-N-O bonds in the core and Hf-O-N bonds in the surface of the thin films. • The absorption coefficient calculated using the spectrophotometry data overlapped with that calculated from extinction coefficients. [ABSTRACT FROM AUTHOR]

Estimating acoustic impedance from seismic data is a crucial step in reservoir characterization. While data-driven impedance inversion based on deep learning has shown promising results, it relies heavily on extensive well logs for labeling, which is often impractical in many exploration scenarios. Recently, the zero-shot or few-shot learning performance of Pretrained Foundation Models like Generative Pre-trained Transformer (GPT) and Mask Auto Encoder (MAE) has highlighted that knowledge learned from vast amounts of unlabeled data can be transferred to downstream tasks with minimal labeled data. However, applying Transformer-based representation learning models to 3D seismic data inversion poses three challenges: (1) Computational and memory constraints due to the high-dimensional nature of the data; (2) Difficulty in extracting fine-grained image features using Transformers, hampering high-frequency impedance inversion; (3) Fixed input size in Transformers, leading to inversion artifacts. In this work, we introduce the Seismic Mask Auto Encoder (SeisMAE), a Transformer-based representation model tailored for the inversion of 3D seismic data. It incorporates three key components: (1) Aggregated dimensionality reduction encoding to handle redundancy in seismic data, significantly improving computational efficiency; (2) Multi-scale self-attention feature fusion to enhance the model's capacity for low-level feature representation; and (3) A stitching decoding strategy to eliminate inversion stitching artifacts. Experimental validations highlight the efficacy of our approach. On the synthetic SEAM I dataset, we demonstrate the effectiveness of each component and SeisMAE's superior performance. For real-world data on The Netherlands F3, SeisMAE delivers reliable inversion outcomes with only four labeled examples. We compared SeisMAE against various inversion techniques, including 1D Convolutional Neural Network (1D-CNN), UNet-based, HRNet-based, and TransInver, where SeisMAE exhibited significant advantages. [ABSTRACT FROM AUTHOR]

Seismic acoustic impedance inversion plays an important role in understanding subsurface structures and obtaining subsurface properties. The stochastic approach is one of the methods used for impedance inversion, and it aims to produce more reliable results by accounting for modeling uncertainty. Stochastic inversion represents the uncertainty of a subsurface model as a probability distribution and uses this distribution to estimate model parameters. In this study, seismic acoustic impedance inversion was performed using a Markov-chain Monte Carlo approach, which is a sampling method used in the stochastic process. Utilizing Bayesian inference based on prior information and observed data, we implemented acceptance probabilities and performed acoustic impedance inversion for field data through iterative calculations. We employed a single GPU card to execute the inversion algorithm and conducted a comparative analysis with the results obtained using a cluster composed of multiple CPU cores. Through a computational speed analysis, the efficiency of the algorithm using a GPU was verified, while uncertainty analysis was employed for algorithm validation. Through these analyses, we confirmed the feasibility of applying our developed GPU algorithm to tasks that require the inversion of extensive data, such as high-resolution seismic exploration and CO2 storage monitoring. • In this study, more reliable results can be derived through uncertainty analysis by using a stochastic approach. • It is advantageous to handle large amounts of data by improving the calculation speed by using GPU. • By utilizing only one GPU card in a workstation, the range of users who may use the algorithm may be expanded. [ABSTRACT FROM AUTHOR]

The attainment and maintenance of a low temperature environment is essential for aerospace cryogenic detectors to achieve their required performance. Developing cryocoolers with features of high efficiency, compact structure, and long lifetime is the main challenge for cryogenic detector cooling. In this paper, a high efficiency thermally-coupled two-stage Stirling type pulse tube cryocooler working at 35 K for HgCdTe long wave infrared detector cooling is designed and tested. The thermally-coupled type avoids gas distribution at cold side which minimizes the inter-stage influence. The whole cryocooler is driven by one linear compressor which enables compact structure. The influence of operation frequency and mean pressure is studied by numerical calculation and experiments to determine the optimum operation condition. Acoustic impedance characteristics of both stages and the whole cold finger are also analyzed by comparing performance of cryocooler with different frequency, mean pressure and structure dimensions. The distributions of acoustic power and phase angle are presented to study the relation between impedance characteristic and the cooling performance. Impedance match between compressor and cold finger is also discussed by analyzing the efficiency of the linear compressor and the performance of cryocooler with different pulse tubes. Under optimum impedance match and operation condition of a working frequency of 39.2 Hz and a mean pressure of 2.45 MPa, the cryocooler provides a cooling power of 1 W at 35.1 K with an input electrical power of 150 W, which indicates a relative Carnot efficiency of 5%. This is a rather high efficiency for developed Stirling type multi-stage pulse tube cryocooler working at 35 K with only inertance tubes as phase shifter. The development of this cryocooler lays a solid base for the further optimization to realize a competitive candidate for aerospace cooling requirements. • A two stage Stirling type pulse tube cryocooler for detector cooling is presented. • Systematically analyze the acoustic impedance of both stages. • The optimum impedance match between compressor and cold finger is specified. • A highest cooling power of 1 W and relative Carnot efficiency of 5% is achieved. [ABSTRACT FROM AUTHOR]

Based on micro-stereolithography (μSL) additive manufacturing (AM) followed by the use of the burnable plastic sphere (BURPS) technique, we present the fabrication of porous lead zirconate titanate (PZT) ceramics. A printing slurry was prepared by mixing photocurable ceramic suspensions with various contents of polymethylmethacrylate (PMMA) as a pore-forming agent (PFA). We found that the cure depth increased gradually with increasing PMMA content. The sintered PZT ceramics exhibited a porous microstructure of predominantly spherical pores formed by PMMA, with sizes ranging from ~15 to 35 μm. The porosity of the PZT ceramics increased from 11.3% to 21.9%, corresponding to a decrease in the density from 6.92 to 6.09 g/cm3 due to the increasing PMMA content. As the porosity increased, the acoustic impedance decreased from 24.4 to 12.6 MRayls (106 kg/m2 s). The porous PZT ceramic with 5 wt% PMMA exhibited superior dielectric and piezoelectric properties (d 33 = 525 pC/N, ε r = 2417, tan δ = 0.04) that were comparable to those of ceramics fabricated by conventional methods. These results suggest that μSL technology is a viable alternative for fabricating porous PZT ceramic components, especially pieces with complex geometric structures. [ABSTRACT FROM AUTHOR]

Background: One of the mechanisms of the efficacy of extracorporeal shock wave therapy (ESWT) for impaired muscle coordination of limbs is the destruction of Acetylcholine receptors (AChRs) at neuromuscular junction. The highly increased density of AChRs can change the acoustic impedance, and this change of the acoustic impedance can be the reason that radial shock wave (rESW) destroy AChRs selectively. However, the relationship between applied energy of rESWs and the therapeutic efficacy remains unclear, although some studies compared the clinical efficacy of rESWT between high- and low-energy applications. This study aimed to compare the CMAP change among different energy and pulses of rESW application.Methods: Male Sprauger-Dawley rats were used. A device that generates radial shock waves pneumatically, was used to apply the following six patterns of radial extracorporeal shockwaves in different energy flux densities and pulses to the right calf of each rat: 1, 8000 pulses at 0.045 mJ/mm2; 2, 4000 pulses at 0.09 mJ/mm2; 3, 2000 pulses at 0.18 mJ/mm2; 4, 4000 pulses at 0.045 mJ/mm2; 5, 2000 pulses at 0.09 mJ/mm2; 6, 1000 pulses at 0.18 mJ/mm2. Left calf muscles were considered controls.Results: There was a significant reduction in CMAP amplitude between control and rESW-exposed muscles in the group applied 4000 pulses with EFD at 0.09 mJ/mm2 and the group applied 2000 pulses with EFD at 0.18 mJ/mm2. However, the group applied 8000 pulses with EFD at 0.045 mJ/mm2 and all groups which was exposed to total 180 mJ rESW application did not show a significantly decreased CMAP amplitude compared with the untreated side.Conclusions: Total energy and energy flux density correlate with a decrease in CMAP amplitude by rESW application. These findings could be availed by clinicians in actual clinical setting for the proper application of rESW. [ABSTRACT FROM AUTHOR]

An 8 mm diameter, image-guided, annular array histotripsy transducer was fabricated and characterized. The array was laser etched on a 5 MHz, 1–3 dice and fill, PZT-5H/epoxy composite with a 45 % volume fraction. Flexible PCBs were used to electrically connect to the array elements using wirebonds. The array was backed with a low acoustic impedance epoxy mixture. A 3.6 by 3.8 mm, 64-element, 30 MHz phased array imaging probe was positioned in the center hole, to co-align the imaging plane with the bubble cloud produced by the therapy array. A custom 16-channel high voltage pulse generator was used to test the annular array for focal lengths ranging from 3- to 8-mm. An aluminum lens-focussed transducer with a 7 mm focal length was fabricated using the same piezocomposite and backing material and tested along with the histotripsy array. Simulated results from COMSOL FEM models were compared to measured results for low voltage characterization of the array and lens-focussed transducer. The measured transmit sensitivity of the array ranged from 0.113 to 0.167 MPa/V, while the lens-focussed transducer was 0.192 MPa/V. Simulated values were 0.160 to 0.174 MPa/V and 0.169 MPa/V, respectively. The measured acoustic fields showed a significantly increased depth-of-field compared the lens-focussed transducer, while the beamwidths of the array focus were comparable to the lens. The measured cavitation voltage in water was between 254 V and 498 V depending on the focal length, and 336 V for the lens-focussed transducer. The array had a lower cavitation voltage than the lens-focussed transducer for a comparable operating depth. The histotripsy array was tested in a tissue phantom and an in vivo rat brain. It was used to produce an elongated lesion in the brain by electronically steering the focal length from 3- to 8-mm axially. Real time ultrasound imaging with a Doppler overlay was used to target the tissue and monitor ablation progress, and histology confirmed the targeted tissue was fully homogenized. [ABSTRACT FROM AUTHOR]

For the purpose of reservoir modelling, precise porosity estimation is vital as it directly influences the storage capacity, fluid flow dynamics, and overall productivity of the reservoir. The computation of porosity is a key component of reservoir characterization. The Poro-Acoustic Impedance (PAI), a seismic inversion attribute, has proven to be effective for porosity estimation in hydrocarbon reservoirs. PAI, an extended version of Acoustic Impedance (AI), incorporates porosity information directly, enhancing its utility in forward modelling and seismic data inversion. In this study, offshore oil resources in Iran were examined, focusing on two components: sandstone and carbonate. The results of AI and PAI were compared, indicating that PAI is a suitable attribute for estimating porosity. The correlation between porosity and AI was −45%, while it was −74% with PAI. Moreover, the synthetic seismogram created using PAI aligns more closely with real seismograms. Porosity was estimated using both AI and PAI, with a 72% correlation between the porosity estimated using AI and the actual porosity. However, the correlation increased to 78% when using PAI. Furthermore, the porosity section was calculated using both AI and PAI, concluding that the PAI porosity section aligns more closely with the porosity log and provides a greater contrast in low porosity zones compared to AI. Given that porosity is incorporated into the PAI formula, the PAI porosity section and inversion results can be used as an indicator for evaluating the hydrocarbon capacity of the reservoir. The findings of this research suggest that PAI is an effective attribute for porosity estimation, bridging the gap between seismic data and porosity estimation, thereby enhancing our understanding and exploration of the reservoir. • Porosity estimation using PAI has better accuracy and precision. • The porosity section obtained using PAI is more consistent with the porosity log. • The effect of porosity is directly involved in the inversion procedure. • The PAI formula is simple and effective to use. [ABSTRACT FROM AUTHOR]

This paper presents the fabrication of glasses with chemical formula [(TeO 2) 0.70 – (ZnO) 0.22 – (PbO) 0.08 ] 1-x (MnO 2) x where x = 0.02, 0.04, 0.06, 0.08 and 0.1 using melt quenching technique. The main objective is to explore the structural, elastic and gamma ray shielding efficiency of the glasses. The study was conducted using density and molar volume measurements, X-ray diffraction analysis, Fourier transform infrared analysis, non-destructive ultrasonic analysis, and theoretical assessment of the glasses' gamma ray shielding efficiency using the Phy-X/PSD software. High density values in the range of 5.611–5.735 gcm−3 and the XRD analysis showed no sharp peak indicating the amorphous nature of the glasses. The FTIR spectra revealed the presence of both TeO 3 and TeO 4 structural units. The values of the elastic moduli microhardness, Debye and softening temperatures, acoustic impedance, diffusion constant, Thermal expansion coefficient and latent heat of melting were studied and discussed among others. Efficiency parameters of radiation shielding such as the coefficients of mass and linear attenuation, effective atomic number, half and tenth value layers, mean free path and effective electron density were calculated theoretically and discussed. Based on the results discussed, the studied MnO 2 doped TeO 2 -PbO-ZnO glasses appeared to be mechanically strong, and thermally stable for radiation shielding applications. Moreso, the glasses appeared to be better in terms of radiation shielding efficiency than commercial concrete materials like serpentine, barite, ferrite, and chromite. • MnO 2 doped TeO 2 – PbO – ZnO glass system were fabricated using melt-quenching technique. • FTIR, XRD, non-destructive ultrasonic analysis/technique, and density & molar volume were used in the measurements and characterization of the studied glasses. • The high-density value in the range of 5.611–5.735 gcm−3 were recorded and Elastic moduli, Softening & Debye's temperatures, thermal expansion coefficient (α p), acoustic impedance (Z), latent heat of melting (ΔH m) and diffusion constant (D i) were studied. • Phy-X/PSD software was used in calculating the radiation shielding parameters such as Linear Attenuation Coefficient (LAC), Mass Attenuation Coefficient (MAC), and others and the results are discussed. • High values of density, elastic moduli, LAC, MAC, and other parameters suggests the glasses possess great potential for radiation shielding application. [ABSTRACT FROM AUTHOR]

The air-coupled ultrasonic technique is a reliable method for measuring the stress state of composite plates. This paper aims to address the requirement for efficient and accurate stress measurement of large component composite plates by proposing an air-coupled ultrasonic in-situ measurement method. Ultrasonic Lamb waves can propagate over long distances while maintaining sensitivity to slight changes and are suitable for in-situ stress measurement of CFRP plates. However, due to the serious mismatch in acoustic impedance, the air-coupled ultrasonic Lamb waves have a low signal-to-noise ratio, which can affect the accuracy of stress measurement. Focusing on this problem, the method employs the Lyapunov exponent with a moving window to accurately extract the acoustic-time characteristic instead of just judging the presence or absence of a weak signal compared with the traditional method of using the Lyapunov exponent. To evaluate the effectiveness of the proposed method in different fiber directions of CFRP plates, seven uniaxial tensile specimens are obtained along 0°, 15°, 30°, 45°, 60°, 75°, and 90° fiber directions, respectively. Utilize stress coefficient calibration results K L to realize the uniaxial stress measurement with a spatial resolution of 150 mm. The experimental results demonstrate that the stress measurement errors are within ±7.29 MPa in the range of 0–150 MPa, and the standard deviations of the repeatability measurement experiment are below 4.57 MPa. The proposed method exhibits significant advantages in terms of measurement accuracy and repeatability compared with traditional stress methods based on peak extraction or cross-correlation. It is a suitable technique for health monitoring and evaluation of composite plates. [ABSTRACT FROM AUTHOR]

• Flow-through thermoacoustic refrigerator is a novel method for cooling cryogenic hydrogen. • Porous stack can be used as a catalytic bed for ortho-parahydrogen conversion. • Stack second-law efficiencies near 60% are predicted. • Supplied acoustic power and hydrogen flow rate should be adjusted in off-design operational conditions. • Hydrogen-based stacks can outperform helium setups. Direct cooling of cryogenic hydrogen can be achieved by flow through a stack or regenerator of a thermoacoustic refrigerator. In addition, using a catalytic stack, the ortho-parahydrogen transformation can be conveniently realized in the same device. Analysis of this system element is carried out by integrating one-dimensional thermoacoustic equations with addition of empirical ortho-parahydrogen conversion reaction. Calculations in a standing-wave catalyzed setup demonstrate a selection process for optimal acoustic impedance and stack pore dimensions, showing significant advantage over non-catalyzed hydrogen- and helium-based stacks of similar kind. Results are presented for hydrogen flow characteristics and distributed heat load due to ortho-parahydrogen conversion inside a stack. The stack performance is also quantified at variable flow rate of hydrogen, stack length, mean pressure, and supplied acoustic power. [ABSTRACT FROM AUTHOR]

• Four most common GBs were determined from EBSD-SEM analysis. • The GB can weaken the heat and thermal strain propagations in YSZ. • The weakening effect of GBs strongly depends on their misorientation angle. • Acoustic impedance primarily accounts for the weakening effect of GBs. The rapid temperature change or thermal shock is inevitable in many engineering applications of polycrystalline yttria-stabilized zirconia (YSZ). Nevertheless, the thermal shock response of YSZ especially its dependence on the grain boundary (GB) structure in YSZ remains almost unknown to date. In this study, the effect of the GB on thermal shock behaviors of YSZ ceramics was investigated by molecular dynamics (MD) simulations in conjunction with experimental characterizations. According to the distribution of misorientation angles of GBs experimentally extracted from our sintered YSZ samples, four most common GBs with a misorientation angle ranging from 35° to 63° were constructed in MD simulations through the annealing technique. The thermal shock simulations on the bi-crystalline YSZ with such GBs show a weakening effect of the GB on the thermo-elastic strain wave, which is found to be the most significant in the [100]/[111] GB and almost vanish in its [110]/[111] counterpart. Our simulations also reveal that the weakening effect of GB on the thermo-elastic strain wave is majorly attributed to the impedance mismatch between its two adjacent grains, although the grain-boundary thermal resistance observed also can weaken the temperature wave after crossing GBs. These findings provide valuable atomic insights into the thermomechanical behaviors of YSZ under thermal shock, which will guide the design of microstructures of YSZ for some special applications in solid oxide fuel cells and thermal barrier coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

Medical ultrasound transducers are being used to acquire medical image information from a patient. In order to acquire high-quality images, studies have been conducted to improve the performance of the transducer. Among them, the high acoustic impedance de-matching layer is effective in improving the sensitivity and bandwidth of the transducer using the backward reflected wave. First, the performance trend of the transducer according to the thickness of the acoustic de-matching layer was analyzed through theoretical calculation and finite element method. It was confirmed that the sensitivity and bandwidth of the transducer increased by adjusting the time delay of the backward reflected wave according to the thickness of the acoustic de-matching layer. Based on the analyzed results, a new structure of a transducer applied with a double-sided FPCB was devised. The time delay of the backward reflected wave was simply controlled by changing the thickness of the polyimide in the FPCB. The bandwidth of the transducer can be increased by changing the thickness of the polyimide in the FPCB. Also, a prototype of a transducer having a designed structure was manufactured and its performance was measured, and it was confirmed that the designed structure was effective in increasing the bandwidth of the transducer. [Display omitted] • Analysis of high acoustic impedance de-matching layer structure through theory and FEA. • Analysis of the trend of the synthesized wave generated from the main wave and reflected wave. • Devised structure of the ultrasonic transducer for broad bandwidth using a double-sided FPCB. [ABSTRACT FROM AUTHOR]