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Acoustic energy dissipates in multi-phase or multi-boundary materials. Hybrid composites are described as multi-phase with many interfaces between their materials. The current research proposes the study of the acoustic behavior of polymeric hybrid composites by estimating the time, velocity, and hybrid composite acoustic impedance. Two groups of hybrid composites were prepared, including unsaturated polyester with PMMA, except one with HDPE and the other with PS. Each group had 28%, 35%, and 40% weight fractions. An ultrasonic test measured the time to determine the velocity and then the acoustic impedance later. The results showed that increasing the weight fraction will increase the density with respect to the density of the reinforcing material. Different ultrasonic times were obtained with increasing weight fractions. As the weight fraction of PS increased, the time increased; unlike the velocity, it decreased but increased with density. In contrast, this behavior was changed if the hybrid had PE. The highest acoustic impedance was at 28% UP/PMMA + PS. In conclusion, UP/PMMA + PS can dissipate ultrasonic waves more than UP/PMMA + PE.

To improve the acoustic radiation performance of the spherical transducer, a prestressed layer is formed in the transducer through fiber winding. The influence of the prestressed layer on the transducer is studied from the effects of the radial prestress ([Formula: see text][Formula: see text]) and acoustic impedance, respectively. First, a theoretical estimation of [Formula: see text][Formula: see text] is established with a thin shell approximation of the prestressed layer. Then, the acoustic impedance is measured to evaluate the efficiency of sound energy transmission within the prestressed layer. Further, the ideal effects of [Formula: see text][Formula: see text] on the sound radiation performances of the transducer are analyzed through finite element analysis (FEA). Finally, four spherical transducers are fabricated and tested to investigate their dependence of actual properties on the prestressed layer. The results show that with the growth of [Formula: see text][Formula: see text], the acoustic impedance of the prestressed layer grows, mitigating the enormous impedance mismatch between the piezoelectric ceramic and water, while increasing attenuation of the acoustic energy, resulting in a peak value of the maximum transmitting voltage response ([Formula: see text]) at 1.18 MPa. The maximum drive voltage increases with [Formula: see text][Formula: see text], leading to a steady growth of the maximum transmitting sound level ([Formula: see text]), with a noticeable ascend of 3.9 dB at a 3.44 MPa [Formula: see text][Formula: see text]. This is a strong credibility that the prestressed layer could improve the sound radiation performance of the spherical transducer.

A major experimental research area in material equation-of-state today involves the use of off-Hugoniot measurements rather than shock experiments that give only Hugoniot data. There is a wide range of applications using quasi-isentropic compression of matter including the direct measurement of the complete isentrope of materials in a single experiment and minimizing the heating of flyer plates for high-velocity shock measurements. We propose a novel approach to generating quasi-isentropic compression of matter. Using analytical modeling and hydrodynamic simulations, we show that a working fluid composed of compressed water, generated by an underwater electrical explosion of a planar wire array, might be used to efficiently drive the quasi-isentropic compression of a copper target to pressures ∼2 × 1011 Pa without any complex target designs. [ABSTRACT FROM AUTHOR]

High-performance broadband ultrasound transducers provide superior imaging quality in biomedical ultrasound imaging. However, a matching design that perfectly transmits the acoustic energy between the active piezoelectric element and the target medium over the operating spectrum is still lacking. In this work, an anisotropic gradient acoustic impedance composite material as the matching layer of an ultrasonic transducer was designed and fabricated; it is a non-uniform material with the continuous decline of acoustic impedance along the direction of ultrasonic propagation in a sub-wavelength range. This material provides a broadband window for ultrasonic propagation in a wide frequency range and achieves almost perfect sound energy transfer efficiency from the piezoelectric material to the target medium. Nano tungsten particles and epoxy resin were selected as filling and basic materials, respectively. Along the direction of ultrasonic propagation, the proportion of tungsten powder was carefully controlled to decrease gradually, following the natural exponential form in a very narrow thickness range. Using this new material as a matching layer with high-performance single crystals, the −6 dB bandwidth of the PMN-PT ultrasonic transducer could reach over 170%, and the insertion loss was only −20.3 dB. The transducer achieved a temporal signal close to a single wavelength, thus there is the potential to dramatically improve the resolution and imaging quality of the biomedical ultrasound imaging system. [ABSTRACT FROM AUTHOR]

Shales represent strongly intrinsic vertical transverse isotropy (VTI) property or polar anisotropy. The presence of vertically aligned fractures makes shale exhibit orthogonal anisotropy and the seismic responses have azimuthal variation. Conventional linearized PP-wave reflectivity expression for orthorhombic (ORT) media includes at least 8 parameters to be inverted, and the amplitude inversion based on such equations can be highly ill-posed. In this paper, we derive a modified PP-wave approximation of reflection coefficients in ORT media and propose a two-step strategy based on the Bayesian-framework inversion method. The new equation represents the seismic response of polar anisotropy and azimuthal anisotropy separately, and it consists of only 5 model parameters to be inverted. Three of these model parameters are azimuthal independent: A—acoustic impedance, B—anisotropic shear modulus and C—horizontal P-wave phase velocity (along the fracture strike), and two of them are azimuthal dependent: D—azimuthal anisotropic gradient and E—horizontal P-wave anisotropy parameter. Accuracy analysis demonstrates that the derived approximation has similar accuracy to the existing approximation. A stepwise inversion strategy is proposed to invert azimuthal-independent parameters and azimuthal-dependent parameters separately. Synthetic tests show that the proposed strategy is more stable and better conditioned than the existing multi-parameter simultaneous inversion. Field seismic data set of a fractured shale-gas reservoir is also used to demonstrate the stability and accuracy of the proposed inversion method. Article Highlights: PP-wave reflection coefficient is derived in terms of only 5 model parameters for orthorhombic media. Three of them are azimuthal independent: A—acoustic impedance, B—anisotropic shear modulus, C—horizontal P-wave phase velocity (along the fracture strike), and the others are azimuthal dependent: D—azimuthal anisotropic gradient, and E—horizontal P-wave anisotropy parameter A stepwise inversion strategy for inverting azimuthal-independent parameters and azimuthal-dependent parameters is proposed Tests on synthetic and field seismic datasets imply that the proposed inversion method has the potential to generate reliable results of the model parameters for reservoir characterization [ABSTRACT FROM AUTHOR]

The present work focuses on the ultrasonic characterisation of the binary mixture having constituent liquids, 2,3-dichloroaniline and methanol/ethanol, by measuring their density, viscosity, ultrasonic velocity and estimating thermo-physical parameters at 25°C. The density, viscosity, ultrasonic velocity, acoustic impedance and relative association decay, while compressibility and free length increase with the increase in mole fraction of solvent in the present binary mixture. An anomalous change is received in excess molar volume, free volume, thermal relaxation time, Gibbs free energy and ultrasonic absorption up to 80% solvent mole fraction. The analysis reveals that the binary mixture 2,3-DCA+ methanol has a good intermolecular interaction strength, and is more structural and less corrosive than 2,3-DCA+ ethanol due to the formation of excess hydrogen bonding at 70% solvent mole fraction. [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]

In a number of advanced materials processing applications, including float zone refining of electronic materials, forming of metallic glasses and induction melting of light alloys, oscillatory and non-oscillatory electromagnetic forces associated with the processing application are found to enhance surface shape, nucleation of precipitates, evolution of crystal nucleation sites, segregation of alloy components, grain refinement and degassing [1]-[3]. For cases where the material being processed is containerized and where the time dependence is oscillatory, these forces give rise to acoustic waves which carry energy to the boundaries of the containerized volume leading to a reduction in process efficacy should the container not present the proper acoustic impedance. This paper considers acoustic energy exchange between the molten alloy and the crucible of an induction furnace and the attendant impact on degassing. [ABSTRACT FROM AUTHOR]

The prolific Oligocene-Miocene Asmari Formation is the primary reservoir rock hosting important hydrocarbon resources in Iran and consists of fluvial/deltaic siliciclastic and shallow marine carbonate rocks in the Hendijan Field. Due to the significant facies variability of the formation, the presence and quality of the reservoir pose a significant uncertainty in the characterization of the reservoir. This study compares two facies models, one based on well logs only and the second based on estimated facies volumes as a secondary variable in facies modelling. The petrophysical evaluation with microscopic thin sections and electrofacies analysis were used to classify the facies and determine the reservoir quality. As a result, the Ghar Member was identified as a highly porous interval, while the lower part of the Asmari Formation is characterized by tight facies. A sequential Gaussian simulation (SIS) algorithm was used to build the 3D facies model on the basis of the well logs. Acoustic impedance, shear impedance and density (derived from pre-stack inversion) were used as inputs to an artificial neural network to generate acoustic and density log volumes. Using electrofacies cut-offs, facies volume was constructed and used as a secondary variable to improve the initial facies model. The final facies model was compared with the blind well to check the validity of the prediction and satisfactory results were obtained. Since the values are present in all the cells of the reservoir (the traditional facies model only has values for the well location), the estimated facies volume is an accurate variable in the prediction of the facies model for the Asmari reservoir and for this reason the secondary facies model is more reliable than the primary one. [ABSTRACT FROM AUTHOR]

In order to apply the nonlinear energy sink (NES) to reduce the low-frequency noise inside a 3D acoustic cavity with an impedance boundary, a two degrees-of-freedom (DOF) dynamic model of the coupled system of one damped acoustic mode of a regular 3D acoustic cavity and a nonlinear membrane absorber as the NES is established. The damping coefficient of the acoustic mode is obtained based on the finite element analysis method and the relationship of the boundary impedance and the absorption coefficient of the cavity. Based on the set-up of the system, the damping coefficient of the acoustic mode is determined. The frequency responses and the targeted energy transfer (TET) phenomenon of the coupled system are analyzed, and the theoretical and numerical results of the frequency responses of the system are in good agreement with the experimental ones. The effects of the wall impedance of the cavity on the optimal TET are discussed. With the increase in the impedance ratio of the wall, the amplitude of the acoustic displacement plateau decreases, and the frequency bandwidth of the plateau and the two thresholds of the optimal TET interval of the excitation increase. It provides a comprehensive theoretical model and experimental basis for the application of NES in the actual complex structure and provides a reliable design method and control strategy for controlling vehicle interior low-frequency broadband noise. [ABSTRACT FROM AUTHOR]

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An optimized multi-step index (MSI) 2-LP-mode fiber is proposed and fabricated with low propagation loss of 0.179 dB/km, low intermodal crosstalk and excellent bend resistance. We experimentally clarified the characteristics of backward Brillouin scattering (BBS) and forward Brillouin scattering (FBS) induced by radial acoustic modes (R0,m) in the fabricated MSI 2-LP-mode fiber, respectively. Via the use of this two-mode fiber, we demonstrated a novel discriminative measurement method of temperature and acoustic impedance based on BBS and FBS, achieving improved experimental measurement uncertainties of 0.2 °C and 0.019 kg/(s·mm2) for optoacoustic chemical sensing. The low propagation loss of the sensing fiber and the new measurement method based on both BBS and FBS may pave the way for long-distance and high spatial resolution distributed fiber sensors. [ABSTRACT FROM AUTHOR]

Single component organic ferroelectrics of spirooxazacamphorsultam derivatives, 1-SSR and 1-RRS, exhibit well-defined ferroelectricity (Ps = 2.2 μC cm−2) and piezoelectricity (d33 = 10 pC N−1) below their melting point. More importantly, they possess a low acoustic impedance value of 2.7 × 106 kg s−1 m−2, which is well-matched with body tissues. [ABSTRACT FROM AUTHOR]

A wire mesh liner possesses a better acoustic linearity to high sound pressure level (SPL) than a perforated liner, but lacks an accurate impedance model. Thus, its nonlinear effect due to high SPL is studied in this paper. A jet simulation of mesh orifices (two-dimensional slits) is conducted. It reveals that an approximation to the nonlinear loss in an existing model ("A Model for the Acoustic Impedance of Linear Suppressor Materials Bonded on Perforated Plate," AIAA Paper 1981-1999, Oct. 1981) includes implicitly linear loss and neglects the effect of the orifice distribution uniformity, and so the nonlinearity of distributed micro-orifices is overestimated. This accords with the experimental result in an impedance tube that the high-SPL resistance is overestimated for a fine mesh. Meanwhile, it is indicated that the discharge coefficient is overestimated in the existing model for neglecting the vena contracta at least at the maximum jet of a coarse mesh, and so the high-SPL resistance is underestimated. Therefore, the nonlinear loss factor Fnl is defined herein to exclude the linear loss and avoid the deviation from the jet contracta of the mesh, which presents a better prediction. Finally, an empirical relation of Fnl considering the orifice diameter and a correction to the reactance are given experimentally, and thus, a more accurate impedance model of the wire mesh liner is established. [ABSTRACT FROM AUTHOR]

Petrophysical properties are the least explored parameters in the Mahanadi basin in the eastern Indian margin. We have used 2D seismic reflection data along a profile AC with available well logs of the Expedition-01 of the Indian National Gas Hydrates Program (NGHP) for the evaluation of lateral variation of porosity – a petrophysical property. The seismic line passes through the Sites NGHP-01-19B in the AB section, and NGHP-01-09A in the BC section. The porosity is estimated using two different approaches based on acoustic impedance (AI) transformation and direct seismic inversion. The AI transformation approach fails to decipher consistent porosity distributions whereas the direct seismic inversion approach provides satisfactory results along seismic line AC (AB and BC) in the Mahanadi Offshore region. The AI transformed porosity section illustrates erroneous porosity values within the target zone, irrespective of a strong coefficient of determination (R 2 ) of 0.82 and 0.85 between AI and porosity at sites NGHP-01-19B and NGHP-01-9A, respectively. The accuracy of the porosity results obtained from the direct inversion approach depends on the best linear regression fit established between acoustic and porosity reflectivity-based models with a coefficient of determination as 0.91 at Site NGHP-01-19B and 0.94 at Site NGHP-01-9A. The porosity distributions are also corroborated with the density-porosity log values, and it is observed that porosity from direct seismic inversion is consistent with the porosity log information at respective sites. The porosity results at the two sites signify the overall good performance of the direct seismic inversion method and also indicate that the probability of free-gas occurrences in shallow sediments is higher compared to that of gas-hydrates. [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]

The development of composite materials with good acoustic vibration performance is an effective way to alleviate the shortage of wood resources for musical instrument soundboards. To explore the possibility of wood-plastic composite materials applied in musical instrument soundboards, the mechanical properties preparation method of composite materials was used as a reference to study the influence of wood powder content and compatibilizer content on the acoustic vibration performance parameters ( specific dynamic elastic modulus, sound radiation quality constant, acoustic impedance, logarithmic decay rate) of composite materials, and comparison with traditional wood for musical instrument soundboards to determine wood powder and compatibilizer content with superior acoustic vibration properties. The research results showed that the wood powder content had a great influence on the acoustic vibration performance of wood-plastic composites. When the wood powder content increased from 60% to 80%, the acoustic vibration parameters acoustic impedance ω, logarithmic decay rate δ, specific dynamic elastic modulus value of E/ρ increased, and the vibration effect decreased slightly. In the preparation of wood-plastic composite materials, the content of compatibilizer had a great influence on the sound quality of the composite material. When 65% wood powder content was used, the content of compatibilizer accounted for 7% of wood powder content to prepare the composite, a relatively good overall performance of acoustic vibration can be obtained. Compared with the existing soundboard materials for musical instruments, the ω value (2. 21 Pa·s/ m) of the wood-plastic composite material in the experiment was close to that of American spruce (2. 20 Pa·s/ m), and the δ was smaller than that of the wood-carbon fiber composite soundboard, but there was also a problem that the sound radiation quality constant R was smaller than that of the wood-glass fiber composite soundboard, and the specific dynamic elastic modulus was relatively small, follow-up research on this issue should be carried out. [ABSTRACT FROM AUTHOR]

There is a growing interest in multifunctional composites and in the identification of novel applications for recycled materials. In this work, the design and fabrication of multiple particle-loaded polymer composites, including micronized rubber from end-of-life tires, is studied. The integration of these composites as part of ultrasonic transducers can further expand the functionality of the piezoelectric material in the transducer in terms of sensitivity, bandwidth, ringing and axial resolution and help to facilitate the fabrication and use of phantoms for echography. The adopted approach is a multiphase and multiscale one, based on a polymeric matrix with a load of recycled rubber and tungsten powders. A fabrication procedure, compatible with transducer manufacturing, is proposed and successfully used. We also proposed a modelling approach to calculate the complex elastic modulus, the ultrasonic damping and to evaluate the relative influence of particle scattering. It is concluded that it is possible to obtain materials with acoustic impedance in the range 2.35–15.6 MRayl, ultrasound velocity in the range 790–2570 m/s, attenuation at 3 MHz, from 0.96 up to 27 dB/mm with a variation of the attenuation with the frequency following a power law with exponent in the range 1.2–3.2. These ranges of values permit us to obtain most of the material properties demanded in ultrasonic engineering. [ABSTRACT FROM AUTHOR]

Low-frequency noise control in buildings is a critical issue because of the weak sound insulation in low frequencies (<200 Hz) for doors and partitions. In the present study, an analytical model has been proposed to specify the relationship between the acoustic parameters, such as acoustic impedance, of honeycomb, and the honeycomb geometry has been investigated to vary the resonance frequency of the honeycomb structures and increase the amount of sound absorption coefficient. In this regard, three materials (polycarbonate, polypropylene, and polyurethane), seven angels (45°, 30°, 15°, 0°, −15°, −30°, −45°), and two cell arrangement (1 × 3 and 2 × 6 state) were considered to discern the effect of these parameters on the sound absorption coefficient. Sound absorption in the frequency range of 1 to 500 Hz for angles of 45°, 30°, 15°, 0°, −15°, −30°, and −45° were demonstrated using MATLAB software. A comparison of the results shows that the greatest absolute value of the angle is caused by the highest sound absorption coefficient. By comparing the absorption coefficient values of all three materials, it can be concluded that the 1 × 3 state has higher absorption than the 2 × 6 state; also, the number of resonance peaks of polyurethane material for all angles is greater than the other two materials in the same frequency range. Then, in the first loading type orientation, for having more sound absorption, the panel with the honeycomb core of polyurethane and 1 × 3 state is recommended for cells with an internal angle of −45° in the case study of the present research. [ABSTRACT FROM AUTHOR]

In seismic data analysis, acoustic impedance may be used for predicting the porosity of a sedimentary layer with known lithology, where the influence on impedance from pore fluid is known. This method typically assumes that the stiffness of the rock frame is solely a function of porosity and that there is no variation in stiffness between rocks with the same composition and porosity. However, contact cementation can cause an increase in rock frame stiffness with no significant reduction in porosity. This means that rocks with similar porosities and varying degrees of cementation would have significantly different elastic moduli; thus, attempting to derive porosity from seismic impedance alone would incur errors. The primary goal of this study is to assess how significant this error is for porosity prediction. The secondary goal is to calculate the dry rock frame stiffness across the field and evaluate to what extent the time of hydrocarbon placement affects the lithification of the rock. To fulfill these objectives, we studied petrophysical logs and core data from the Dan field and derived seismic impedance, porosity and stiffness expressed in terms of Biot's coefficient for 14 wells across the field. Trends defined between acoustic impedance, porosity, and Biot's coefficient in the Maastrichtian unit of the Dan field showed that, for a given porosity and water saturation in the oil zone, the chalk located at the crest of the reservoir is softer than the chalk located at the flanks of the field. We also found that chalk is stiffer in the down‐faulted north‐western part of the field for a given porosity and water saturation in the oil zone. In the water zone, no difference was found. We speculate that contact cementation downflank in the northwest block caused an increase in the chalk stiffness without reducing the porosity, while earlier hydrocarbon filling of the south‐eastern block and the crest of the structure delayed contact cementation between the chalk particles. This difference in contact cementation between rocks of the same porosity causes porosity prediction from acoustic impedance to vary by up to six porosity units. [ABSTRACT FROM AUTHOR]

The transient vortex dynamics within a microsecond-level acoustic cycle were numerically investigated when an orifice–cavity structure, which is a unit component of an acoustic liner, was subjected to high-intensity acoustic waves. Three-dimensional vortex-acoustic coupling fields were determined by solving the compressible linearized Navier–Stokes equations (LNSEs) and considering the nonlinear thermoviscous effect around the micro-orifice. First, the LNSE results were well validated by literature results in terms of the sound absorption coefficient, reflection coefficient, acoustic resistance, acoustic reactance, acoustic impedance, and the spatial features of acoustically induced vortex structures. Subsequent cross correlation analysis demonstrated that attenuated standing-waves were generated inside the back cavity when the incident acoustic wave propagated across the orifice. Aeroacoustic energy analysis revealed that the periodic production of vortex kinetic energy contributed more to the sound attenuation in the orifice structure than the viscous dissipation effect. Then, the acoustically induced vortex dynamics were characterized in terms of a phase-dependent evolution process, and the formation, convection, and dissipation regions were classified. Finally, dynamic mode decomposition analyses were conducted to extract the dominant vortex structures by determining their frequency spectra. The dominant modes contained large-scale vortices around the orifice, while the high-order modes contained a series of small-scale vortices toward the upstream incident tube and downstream cavity. [ABSTRACT FROM AUTHOR]

Recently, dotted-art MPPs have been proposed in which a designed pattern is made with the holes. In such a case, the MPP becomes heterogeneous in general. However, existing theories used for the prediction of the absorption characteristics of MPPs assume homogeneity. Therefore, the elaboration of a method for heterogeneous MPPs needs to be performed. In previous work, the authors proposed a method to predict the absorption characteristics of a heterogeneous MPP by using synthesized impedances of each part with different parameters; this is called the synthetic impedance method (SIM) in the present paper. The SIM can potentially be used for various heterogeneous MPPs; however, its scope of applicability needs to be clarified. Furthermore, in proposing a design concept of dotted-art heterogeneous MPPs, the condition that would make the designed MPPs fall within the scope of the SIM needs to be determined. Therefore, in this study, in order to clarify the scope of the applicability of the SIM, twelve samples are first prepared, and then measured sound absorption characteristics and predicted ones are compared and examined in terms of prediction errors. The results show that there are two conditions that should be met to produce predictable heterogeneous MPPs: (1) holes are distributed over the entire surface of the specimen, and (2) the hole spacing is constant. Considering these conditions, a design concept for a dotted-art heterogeneous MPP is proposed: two types of holes, larger holes for the pattern and smaller holes for the background, should be used to meet the above two conditions. Case studies with nine prototypes show that the SIM can make predictions for dotted-art heterogeneous MPPs fabricated according to the concept described above. [ABSTRACT FROM AUTHOR]

In this work, microspeaker frequency response was determined based on measurement and simulation. The vents after the rear chamber of the microspeaker were covered with ventilation cloths. Two types of ventilation cloths (acoustic cloths) are commonly used in electroacoustic products, non-woven and woven. Non-woven cloths (5 nos.) consist of irregular meshes and woven cloths (5 nos.) consist of regular meshes. The equivalent circuit model of the microspeaker was formulated by considering five types each of non-woven and woven ventilation cloths. The acoustic properties of the ventilation cloths were estimated from the measured frequency response of the microspeaker and by subsequent use of particle swarm optimization algorithm. Estimated value of the acoustic impedances of the ventilation cloths were used in an equivalent circuit model of the microspeaker for the simulated frequency responses and subsequently compared with the anechoic chamber measurements. Based on the results, the equivalent circuit adequately simulated the measured frequency response of the microspeaker and the estimations of the acoustic impedances of the ventilation cloths were in good agreement with the measured frequency responses of the microspeaker. [ABSTRACT FROM AUTHOR]

The preparation of underwater acoustically transparent polyurethane with excellent acoustic transparency, hydrophobicity, and electrical insulation is the current bottleneck prior in the underwater acoustic system. In this work, we synthesized a series of acoustically transparent polybutadiene‐based polyurethane (FPU) modified with a,ω‐dihydroxypoly[(3,3,3‐trifluoropropyl)methylsiloxane] (PTFPMS) by prepolymerization method. The influence of the PTFPMS content on the hydrophobicity, acoustic transparency, electrical insulation, and mechanical properties of FPU were investigated. When the amount of PTFPMS was 10 wt%, the water absorption of FPU reached the minimum of 0.261%, which was 42.9% lower than that of neat polyurethane. Moreover, the acoustic impedance of FPU decreased to 1.584 × 105 g/cm2∙s, which was very close to that of seawater and indicated a favorable acoustic transparency. In addition, the volume resistivity and surface resistivity of FPU were 5.20 × 1014 Ω cm and 2.42 × 1014 Ω cm, respectively, suggesting an excellent electrical insulation. These results revealed that the as‐prepared FPU has promising applications in the fields of underwater acoustically transparent encapsulant. [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]

An acoustic matching layer is an essential component of an ultrasound transducer to achieve maximum ultrasound transmission efficiency. Here, we develop a flexible printed circuit board (FPCB) with a composite structure consisting of multiple polyimide and copper layers and demonstrate it as a novel acoustic matching layer. With a flexible substrate and robust ACF bonding, the FPCB not only serves as an acoustic matching layer between piezoelectric elements and the surrounding medium but also as a ground for the electrical connection between the transducer array elements and the folded substrate. A 1D linear ultrasound transducer array with the FPCB matching layer exhibits larger output pressure, wider -3dB bandwidth, and higher ultrasound beam intensity compared to that of an ultrasound transducer array with the alumina/epoxy matching layer, which is one of the most commonly applied composite matching layers. The enhanced transmission performance verifies that the proposed FPCB is an excellent matching layer for 1D linear ultrasound transducer arrays. [ABSTRACT FROM AUTHOR]

Understanding the influence of rare‐earth ions in tellurite‐rich glass is vital for developing the technology. With this motivation, the present study analyzes the radiation shielding, physical, structural, mechanical, and acoustic features of the tellurite glasses added Nd2O3 rare earth material. Five different glasses coded as TMNd0.0–TMNd1.9 are simulated via MCNPX Monte Carlo code by varying the concentration of neodymium oxide (Nd2O3) and the related characteristics are evaluated between 0.01 and 10 MeV. The obtained results reveal that Nd2O3 has a favorable influence on the radiation shielding characteristics of the preferred glass sample. To assess the relation between Nd2O3 concentration in tellurite glass and corresponding structural and mechanical changes in candidate glasses, Makishima–Mackenzie theory is applied and mechanical moduli are extracted. The structure and dimensionality of the preferred samples are derived based on the Bergman and Kantor model for fluid and compositions with the help of the fractal bond connectivity. In addition, the longitudinal velocity (VL), transverse velocity (VS), mean velocity (Vmean), and acoustic impedance (Zi) related to the TMNd glasses are evaluated. [ABSTRACT FROM AUTHOR]

Seismic data are considered crucial sources of data that help identify the litho-fluid facies distributions in reservoir rocks. However, different facies mostly have similar responses to seismic attributes. In addition, seismic anisotropy negatively affects the facies predictors extracted from seismic data. Accordingly, this study aims at estimating zero-offset acoustic and shear impedances based on partial-stack inversion by two methods: statistical modeling and a multilayer feed-forward neural network (MLFN). The resulting impedance volumes are compared to those obtained from isotropic simultaneous inversion by using impedance logs. The best impedance volumes are applied to Thomsen's anisotropy equations to solve for the anisotropy parameters Epsilon and Delta. Finally, the shear and acoustic impedances are transformed into elastic properties from which the facies and fluid distributions are predicted by using the logistic regression and decision tree algorithms. The results obtained from the MLFN show better matching with the impedance and facies logs compared to those obtained from isotropic inversion and statistical modeling. [ABSTRACT FROM AUTHOR]

Binary liquid mixtures of furfural with toluene and nitrobenzene were examined for ultrasonic velocity, viscosity and density at a temperature of 308.15 and 318.15 K in various mole fractions. The calculated thermodynamic properties from density, viscosity, ultrasonic velocity and some excess parameters like Excess Volume(VE), Deviation in Isentropic Compressibility(ΔKS), Deviation in Viscosity(Δη), Deviation in Intermolecular Free Length(ΔLF), Deviation in Intermolecular Free Volume(ΔVF) and Deviation in Acoustic Impedance(ΔZ) were determined and found the proper coefficients for a polynomial equation of the Redlich-Kister type, from which the theoretical values were calculated. The interaction ability of the binary liquid mixtures was investigated, as well as the deviations of the binary liquid mixtures from their ideal behavior were studied based on the experiment and theoretical values. [ABSTRACT FROM AUTHOR]

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Accurate reservoir characterization is necessary to effectively monitor, manage, and increase production. A seismic inversion methodology using a genetic algorithm (GA) and particle swarm optimization (PSO) technique is proposed in this study to characterize the reservoir both qualitatively and quantitatively. It is usually difficult and expensive to map deeper reservoirs in exploratory operations when using conventional approaches for reservoir characterization hence inversion based on advanced technique (GA and PSO) is proposed in this study. The main goal is to use GA and PSO to significantly lower the fitness (error) function between real seismic data and modeled synthetic data, which will allow us to estimate subsurface properties and accurately characterize the reservoir. Both techniques estimate subsurface properties in a comparable manner. Consequently, a qualitative and quantitative comparison is conducted between these two algorithms. Using two synthetic data and one real data from the Blackfoot field in Canada, the study examined subsurface acoustic impedance and porosity in the inter-well zone. Porosity and acoustic impedance are layer features, but seismic data is an interface property, hence these characteristics provide more useful and applicable reservoir information. The inverted results aid in the understanding of seismic data by providing incredibly high-resolution images of the subsurface. Both the GA and the PSO algorithms deliver outstanding results for both simulated and real data. The inverted section accurately delineated a high porosity zone ( > 20 % ) that supported the high seismic amplitude anomaly by having a low acoustic impedance (6000-8500 m/s ∗ g/cc). This unusual zone is categorized as a reservoir (sand channel) and is located in the 1040-1065 ms time range. In this inversion process, after 400 iterations, the fitness error falls from 1 to 0.88 using GA optimization, compared to 1 to 0.25 using PSO. The convergence time for GA is 670,680 s, but the convergence time for PSO optimization is 356,400 s, showing that the former requires 88 % more time than the latter., (© 2024. The Author(s).)

Streptomycin is an antibiotic medication used to treat a number of bacterial infections. In the present study ultrasonic velocity (U), density (ρ) and viscosity (η) have been measured at frequency 1 MHz in the binary mixtures. The binary mixtures of streptomycin with water in the concentration range (0.1 to 0.0125%) at 303 K, 308 K, and 313 K using a multifrequency ultrasonic interferometer. The measured value of ultrasonic velocity, density and viscosity have been used to estimate the acoustical parameters namely adiabatic compressibility (βa), relaxation time (τ), acoustic impedance (z), free length (Lf), free volume (Vf) and internal pressure (Pi), Wada’s constant(W), Rao’s constant (R) to investigate the nature and strength of molecular interaction in the binary mixture with water. The obtained results support the occurrence of complex formation, molecular association through intermolecular hydrogen bonding in the binary liquid mixtures. DOI: http://dx.doi.org/10.17807/orbital.v13i4.1465

The estimation of seismic reservoir properties faces difficulties such as delineating deceptive fluid contacts, over-estimating reserves and drilling dry holes. To overcome these problems, sequence stratigraphic and rock physics analyses that were constrained by the compaction trend were implemented in the Sigma Field. Sigma field is located in the Coastal Swamp depobelt, in the distal part. Seismic data from the field and a total of three wells, Sigma-30, 26, and 25 were provided for the analyses. Biostratigraphic data was also given for the field and dated to shale marker Cassidulina-7. The stratigraphic sequence analysis of the wells in field indicate they were deposited in a regressive, transgressive and aggradational episodes, whereas the entire depositional history shows predominantly regressive episode. Three field reservoirs, SM-14 (LST), SM-04 (TST), and SM-02 (HST) were delineated. Depositional analysis of the landscape from sequence stratigraphic analyses of the field indicates that Sigma field reservoirs were deposited in a front region of the delta. Trend to compaction has been generated for the well. Sigma wells showed a normal trend toward compaction. Rock physics analysis of the reservoirs of interest reveals that LST and TST reservoirs have been difficult to distinguish against HST reservoirs which are easy to classify regardless of their depth for fluids in a Vp/Vs crossplot versus acoustic impedance. In the analysis, a pattern is suggested for TST reservoirs. Therefore, this research work shows that fluid discrimination becomes simpler as we go basin ward as the sorting of the reservoir rocks increases with finer grain sand sizes.

The relevance of the research is caused by the need to increase the degree of reliable assessment of the geological structure of complex reservoirs in the presence of a small set of geological and geophysical information, which is ambiguous in predicting and identifying geological objects. In recent decades, companies have widely used various classification algorithms in processing the entire complex of data to reduce the uncertainties of geological interpretation. One of the approaches is application of classification methods to a seismic signal, which divide the object under study into areas that are homogeneous by a number of signs, where geophysical well surveys and core studies are also used, which involves the integration of information. A comprehensive interpretation of seismic and borehole data allows predictingat a qualitative level lithofacies variability in local areas, which contributes to a more rational placement of production wells. The main aim of the research is to consider approaches to analyzing a reliable assessment and forecasting the facies structure when searching for promising objects for the most optimal location of exploration wells when planning drilling, taking into account constantly updated and renewed geological information about the formation. The object of the study is the Paleozoic basement deposits of the southeastern part of the West Siberian Plate, which represent rocks of various material composition, including carbonate differences. Methods include statistical analysis of seismic information and geological and geophysical data. The statistical analysis of the spatial change in the facies environment was performed, on the basis of which reliable zones of the presence of certain facies were identified. The proposed strategy for predicting the prospects of oil and gas potential of the Paleozoic sediments on the example of one of the fields in Western Siberia contributed to the identification of promising zones for future planning of well locations.

The paper presents a new numerical solution as a method for the thermodynamic cycle of a thermoacoustic engine estimation. A mathematical solution for calculating the gas averaged velocity was developed. The proposed method uses acoustic impedance of the engine's thermal core and the dynamic pressure distribution and enables to calculate gas averaged velocity and prower output. The results of power output and thermal efficiency obtained from the numerical solution and experiments performed for the tested traveling-wave engine and presented in this paper. Relative deviation between theoretical and experimental values of thermal efficiency was 10.7%. This study provides a useful approach for the calculation of the produced power of thermoacoustic engines and can be useful in designing of cycle where the power maximization is crucial.

With the need of developing new materials, exploring new phenomenon, and discovering new mechanisms under extreme conditions, the response of materials to high-pressure compression attract more attention. However, the high-pressure state deviating from the Hugoniot line is difficult to realize by conventional experiments. Gas gun launching graded materials could reach the state. In our work, the corresponding Al-Cu composites and graded materials are prepared by tape casting and hot-pressing sintering. The microstructure and the acoustic impedance of the corresponding Al-Cu composites are analyzed to explain the impact behavior of Al-Cu graded materials. Computed tomographic testing and three-dimension surface profilometry machine results demonstrated well-graded structure and parallelism of the graded material. Al-Cu GMs with good parallelism are used to impact the Al-LiF target at 2.3 km/s using a two-stage light-gas gun, with an initial shock impact of 20.6 GPa and ramping until 27.2 GPa, deviating from the Hugoniot line. [ABSTRACT FROM AUTHOR]

Scanning acoustic microscopy (SAM) is a useful observational tool in cellular study as non-invasive living observation is feasible, unlike in conventional optical microscopy. In a previous study, cell morphological changes were successfully visualized using acoustic impedance measurements. These acoustic impedance changes correspond to cell elasticity, mainly reflecting changes in the cytoskeleton. In this study, we evaluate the elastic changes in murine breast cancer cell C127I during mitosis. C127I cells were cultured to ∼75% confluency before measurement, using a transducer with a central frequency of 320 MHz. Dynamic changes during mitosis were successfully mapped using SAM and confirmed by laser confocal microscopy. Cells in prometaphase, anaphase, and telophase, which could previously only be confirmed through immunostaining, were successfully visualized using SAM. This suggests that SAM is capable of distinguishing cells in different mitotic phases based on the changes in acoustic impedance. [ABSTRACT FROM AUTHOR]

Basalt microfiber‐reinforced polyurethane elastomer composites (BMF/PUE) were prepared by semi‐prepolymer method in this study. The degree of microphase separation and quantitative analysis of H‐bonding formation in polyurethane were determined by infrared spectroscopy. The fiber surface and the morphology at the tensile fracture interface of the composite materials were observed by scanning electron microscopy. The mechanical properties of composite materials were further measured on an electronic universal testing machine. Dynamic thermomechanical analysis and acoustic impedance tube were used to study the damping and acoustic properties of composite materials, respectively. The results indicated that the composite material prepared by adding 6 g of basalt microfibers treated with 3 min' crushing had the best overall performance. Compared with the matrix, BMF/PUE showed good sound insulation performance with a much wider effective damping temperature range. On the basis of ensuring its excellent overall performance, the mechanical properties were increased by 50.4% in tensile strength, 28.1% in elongation at break, and 14.2% in tear strength. [ABSTRACT FROM AUTHOR]

The temporal variation in terms of the "time-to-failure" parameter of the recordings of the electrical resistance and the acoustic emissions from concurrent measurements in three cement mortar specimens of prismatic shape that were subjected to a three-point bending test until fracture are studied. The novelty of the work at hand lies in the demonstration that the electrical resistance is described by a power law during the last stages of the loading protocols. The onset of the validity of the power law is indicative of the specimens' imminent fracture, thus providing a useful pre-failure indicator. The above findings are supported by the analysis of the recorded acoustic signals in terms of the F-function and the Ib-value formulations. [ABSTRACT FROM AUTHOR]