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We study the elastic behavior of hexagonal close-packed (hcp) Fe at the high temperature and pressure conditions of the Earth Core, using an embedded-atom method interatomic potential adjusted to those conditions. We calculate diffusivity, elastic constants, density, bulk modulus, shear modulus, and sound velocities vs temperature. We obtain reasonable agreement with ab initio simulations and with other empirical potential simulations. Our densities and shear modulus are slightly higher than those in the preliminary reference earth model for the core. Phase stability is discussed in terms of the Born criteria and free energies, finding that hcp is mechanically stable and that the free energy difference between hcp and body-centered cubic (bcc) is very small compared to the thermal energy. We compare our simulated shear modulus G to several analytical models, obtaining excellent agreement with the Atom in Jelium model by Swift and co-workers. Assuming that the yield strength Y is equal to the shear modulus G , Y = G / 30 , we find reasonable agreement with a recent parametrization of the Steinberg–Guinan model. These results can lead to future large-scale, multi-million simulations of Fe under core conditions for samples with microstructure like grain boundaries and twins, which might be present under those conditions. [ABSTRACT FROM AUTHOR]

We present ab initio simulations of a large system of 2400 particles of molten NaCl to investigate the behavior of collective mode dispersion beyond the hydrodynamic regime. In particular, we aim to explain the unusually strong increase in the apparent speed of sound with wave number, which significantly exceeds the typical positive sound dispersion of 10%–25% observed in simple liquids. We compare dispersions of "bare" acoustic and optic modes in NaCl with ab initio simulations of other ionic melts such as CuCl and LiBr, metallic liquid alloys such as Pb44Bi56 and Li4Tl, and the regular Lennard-Jones KrAr liquid simulated by classical molecular dynamics. Analytical expressions for the "bare" acoustic and optic branches of collective excitations help us to identify the impact of the high-frequency optic branch on the emergence of "fast sound" in binary melts. Our findings show that in ionic melts, the high-frequency speed of sound is much larger than in the simple Lennard-Jones liquids and metallic melts, leading to an observed strong viscoelastic increase in the apparent speed of sound—more than double its adiabatic value. [ABSTRACT FROM AUTHOR]

As elastography, an emerging medical imaging strategy, advances, surface acoustic waves have been utilized to examine superficial tissues quantitatively. So far, most studies are experimental, and a numerical method is needed to cost-effectively investigate surface acoustic wave generation and propagation for technical development and optimization purposes. This study aims to develop a reliable numerical method for simulating impulse-induced surface acoustic waves using the k-wave simulation toolbox. According to the physical process of surface acoustic wave based elastography, the proposed simulation method consists of two stages: compressional wave simulation and elastic wave simulation, which aim to generate acoustic radiation force impulse and elastic waves, respectively. The technical procedures were demonstrated by a wave simulation on a water–tissue model. Meanwhile, three acoustic radiation force modeling methods were adopted. The compressional wave simulation showed that the three force modeling methods could produce similar force distribution in space but largely different amplitudes. The elastic wave simulation confirmed the feasibility of numerically generating surface acoustic waves. The reliability of the simulated waves was verified by a quantitative comparison between the numerically acquired sound speeds and their theoretical expectations and by a qualitative comparison between the numerically generated waves and the experimental observations under similar conditions. In summary, this study confirms k-wave as an effective numerical method for simulating surface acoustic waves for elastography purposes. This study provides an immediate simulation platform for investigating Scholte waves, the surface acoustic wave at a liquid–solid interface, and also, a potential numerical framework to investigate other surface acoustic waves. [ABSTRACT FROM AUTHOR]

Three third-order dielectric constants, 8 electrostrictive constants, 13 third-order piezoelectric constants, and 14 third-order elastic constants for lithium tantalate (LiTaO3) single crystals, which are mainly used in surface acoustic wave (SAW) devices, were determined as part of basic research to realize SAW devices with a low degree of nonlinearity. The third-order dielectric constants were determined by measuring the change in capacitance along selected directions when an alternating electric field was applied to the crystal. The electrostrictive constants were determined by measuring the change in capacitance when static stress was applied. Some of the piezoelectric constants were determined directly from the change in sound velocity due to the application of an alternating electric field, whereas others were obtained from the measured dielectric constants, electrostrictive constants, and the change in sound velocity due to an alternating electric field. In addition, the elastic constants (compliance) were determined using the three aforementioned determined nonlinear constants and the measured small-amplitude ultrasonic velocity change as a function of applied static stress. The measurements performed in the present study are more advanced than those reported for LiNbO3 single crystals in 1987 due to the adoption of the d-form nonlinear piezoelectric equation (instead of the e-form) and a higher degree of precision using dynamic measurement methods. The use of the d-form of the nonlinear piezoelectric equation allows many nonlinear constants to be determined independently from other nonlinear constants, eliminating measurement errors associated with these other constants. The d-form nonlinear constants obtained in the present study were converted to e-form constants to make them applicable to the analysis of nonlinear phenomena in piezoelectric devices. [ABSTRACT FROM AUTHOR]

Picosecond ultrasonics is a technique where coherent acoustic phonons are generated with frequencies in the GHz frequency range. When optical detection is operated in a transparent medium, the interaction of these phonons with the probe pulses yields oscillations in the time domain that reveal Brillouin scattering. Their frequency is at the Brillouin frequency shift, commensurate with the phonon velocity. As the pump–probe experiments are time-resolved, changes in the Brillouin frequency with time can be attributed to changes in sound velocity with depth. As sound velocity is temperature-dependent in liquids, we show that the picosecond ultrasonics technique can be used for temperature depth profiling in liquids. In this work, the concept is proved using the pump absorption itself as a heat source and confronting measured changes in Brillouin frequency with depth with data resulting from the derivation of a 3D modeling of the temperature rise in the liquid. We demonstrate the remote depth profiling of temperature, with measured data spaced at a distance less than the optical wavelength. [ABSTRACT FROM AUTHOR]

Within the low-frequency limit, this work analyzes the viscous absorbing properties of circular clusters and semi-infinite slabs made of rigid scatterers embedded in a fluid, such as air or water. These structures are made of rigid scatterers distributed in a hexagonal lattice, and they are proposed as useful absorbing devices in the core of acoustic black holes or acoustic metasurfaces. It is demonstrated that in both types of structures, an optimum value of the filling fraction produces the maximum absorption in a given frequency band. To avoid heavy numerical simulations, the broadband absorbing power has been obtained using a homogenization theory providing not only the effective acoustic parameters (effective mass and effective sound speed) but also the decay coefficient due to viscosity. An enhancement of the broadband sound absorption can be obtained by using a refractive index gradient allowing an increase of the acoustic energy into the semi-infinite slabs. The theoretical predictions are well supported by numerical simulations based on the finite-element and boundary-element methods, respectively, for the semi-infinite slabs and clusters. These predictions have potential applications in the design of structures and metasurfaces with enhanced absorbing power at low frequencies. The analytical model is further supported by experiments made with a 3D-printed sample. [ABSTRACT FROM AUTHOR]

Experimental studies of the shock wave properties of two epoxy resins with the same composition but different curing temperatures (160 and 200 °C) at up to 330 GPa pressure have been carried out. Laser interferometry was used to record particle velocity profiles at up to 73 GPa pressure while measuring the shock wave velocity. The release sound velocity was experimentally determined in the 3–73 GPa pressure range. Cumulative explosive shock wave generators were used to study the shock Hugoniot of epoxy resins at pressures above 100 GPa. It was shown that the shock compressibility data of both samples are approximated by a single shock Hugoniot within the experimental error. A kink on Hugoniot recorded close to 25 GPa pressure indicates a chemical decomposition in epoxy resin. Above this kink, a change in the shock wave front structure was recorded. Hugoniots of epoxy resin and unidirectional carbon/epoxy composite were compared at up to 370 GPa pressure. [ABSTRACT FROM AUTHOR]

We present the ab initio thermoelastic properties of body-centered cubic molybdenum under extreme conditions obtained within the quasi-harmonic approximation including both the vibrational and electronic thermal excitation contributions to the free energy. The quasi-harmonic temperature-dependent elastic constants are calculated and compared with existing experiments and with the quasi-static approximation. We find that the quasi-harmonic approximation allows for a much better interpretation of the experimental data, confirming the trend found previously in other metals. Using the Voigt–Reuss–Hill average, we predict the compressional and shear sound velocities of polycrystalline molybdenum as a function of pressure for several temperatures, which might be accessible in experiments. [ABSTRACT FROM AUTHOR]

The thermophysical properties and elemental abundances of the noble gases in terrestrial materials can provide unique insights into the Earth's evolution and mantle dynamics. Here, we perform extensive ab initio molecular dynamics simulations to determine the melting temperature and sound velocity of neon up to 370 GPa and 7500 K to constrain its physical state and storage capacity, together with to reveal its implications for the deep interior of the Earth. It is found that solid neon can exist stably under the lower mantle and inner core conditions, and the abnormal melting of neon is not observed under the entire temperature (T) and pressure (P) region inside the Earth owing to its peculiar electronic structure, which is substantially distinct from other heavier noble gases. An inspection of the reduction for sound velocity along the Earth's geotherm evidences that neon can be used as a light element to account for the low-velocity anomaly and density deficit in the deep Earth. A comparison of the pair distribution functions and mean square displacements of MgSiO3–Ne and Fe–Ne alloys further reveals that MgSiO3 has a larger neon storage capacity than the liquid iron under the deep Earth condition, indicating that the lower mantle may be a natural deep noble gas storage reservoir. Our results provide valuable information for studying the fundamental behavior and phase transition of neon in a higher T–P regime, and further enhance our understanding for the interior structure and evolution processes inside the Earth. [ABSTRACT FROM AUTHOR]

We report a kind of coiled-up meta-liners with nonuniform cross sections (CMNC), which can efficiently attenuate low-frequency sound waves under grazing flow with a deep subwavelength thickness (e.g., ∼λ/17 at 500 Hz). At a grazing flow Mach number of 0.26, the average transmission loss of the meta-liner is 12.6 dB at 500–1000 Hz, which is twice as much as that of a double-degree-of-freedom acoustic liner of the same size. Physically, the nonuniform cross-sectional distribution and significant cross-sectional area ratio enhances vortex shedding, thus resulting in severe acoustic energy dissipation. The excellent low-frequency acoustic attenuation performance of CMNC is investigated thoroughly with experimental, theoretical, and numerical methods. This work provides an avenue for low-frequency noise reduction in grazing flow scenarios (e.g., in a high bypass ratio turbofan engine). [ABSTRACT FROM AUTHOR]

Isotropic materials are required to adhere to various mechanical principles due to their limited thermal stability. For instance, it is essential for Poisson's ratio to be within the range of −1 to 0.5, and the longitudinal wave velocity must exceed the transverse wave velocity. Nevertheless, perfect crystals, as anisotropic materials, have the ability to defy conventional rules. Through the integration of high-throughput processes and first-principles calculations, a comprehensive exploration of known materials was conducted, resulting in the establishment of a database featuring an extreme anisotropic mechanism. This included the identification of abnormal Poisson's ratios (with the directional Poisson's ratio ranging from −3.00 to 3.67), the discovery of extreme negative linear compressibility, the determination of the upper and lower limits of the sound velocity, and other associated properties. Several materials with abnormal Poisson's ratios (<−1 or >0.5) were listed, and their peculiar mechanical behavior, wherein the volume decreased counterintuitively with uniaxial tension, was discussed. Finally, this study focused on the velocities of longitudinal and transverse waves, with specific emphasis on materials exhibiting transverse wave velocities that exceeded the longitudinal wave velocities. [ABSTRACT FROM AUTHOR]

The motivation of the present study is to gain insights into the evolution of elastic properties of cemented tungsten carbides (WC) shock compressed to 100 GPa. Seven plate impact experiments—two front surface impact and five release wave overtake—are conducted to make simultaneous measurements of Hugoniot states and longitudinal sound speeds in shocked WC with 3.7wt.% cobalt binder. The sound speeds along with estimates for bulk sound speeds, obtained using the Birch–Murnaghan EoS, are analyzed to determine the elastic moduli—longitudinal, bulk, and shear—as a function of Hugoniot stress. The longitudinal and bulk sound speeds at Hugoniot states of interest are found to increase linearly with longitudinal stress. Consistent with the increase in sound speeds, the longitudinal and bulk moduli also increase with Hugoniot stress; however, the increase in longitudinal modulus is modest when compared to predictions of theoretical models that account for pressure and temperature dependence of elastic moduli, but with no damage. The shear moduli remain nearly constant at ∼ 318 GPa over the range of Hugoniot states investigated. These values are, however, much lower than those predicted by the Steinberg–Guinan model with no damage. Poisson's ratio decreases initially from its ambient value of 0.208 to ∼ 0.199 for Hugoniot stress ≤ 10 GPa indicating consolidation of the WC microstructure with low initial stress; however, with an increase in Hugoniot stress to ∼ 100 GPa, Poisson's ratio increases to ∼ 0.317, indicating degradation of shear moduli with increasing stress. The product of density and Grüneisen parameter (ρ Γ), after an initial spike, remains nearly constant for volumetric strains ≥ 0.07. The maximum average temperature rise is estimated to be ∼ 286 ° C at the highest Hugoniot stress employed in the study. [ABSTRACT FROM AUTHOR]

Water is one of the most abundant substances on earth, but it is still not entirely understood. It shows unusual behavior, and its properties present characteristic extrema unlike any other fluid. This unusual behavior has been linked to the two-state theory of water, which proposes that water forms different clusters, one with a high density and one with a low density, which may even form two distinct phases at low temperatures. Models incorporating the two-state theory manage to capture the unusual extrema of water, unlike traditional equations of state, which fail. In this work, we have derived the framework to incorporate the two-state theory of water into the Statistical-Associating-Fluid-Theory (SAFT). More specifically, we have assumed that water is an ideal solution of high density water molecules and low density water molecules that are in chemical equilibrium. Using this assumption, we have generalized the association term SAFT to allow for the simultaneous existence of the two water types, which have the same physical parameters but different association properties. We have incorporated the newly derived association term in the context of the Perturbed Chain-SAFT (PC-SAFT). The new model is referred to as PC-SAFT-Two-State (PC-SAFT-TS). Using PC-SAFT-TS, we have succeeded in predicting the characteristic extrema of water, such as its density and speed of sound maximum, etc., without loss of accuracy compared to the original PC-SAFT. This new framework is readily extended to mixtures, and PC-SAFT-TS manages to capture the solubility minimum of hydrocarbons in water in a straightforward manner. [ABSTRACT FROM AUTHOR]

The exponential-6 (exp-6) potential is commonly used to model fluids at high densities. In this paper, I propose a new equation of state (EOS) in the form of an analytical expression for the excess Helmholtz free energy of an exp-6 fluid. The EOS is based on extensive Monte Carlo simulations and therefore combines the excellent accuracy of the simulations with the numerical efficiency of a polynomial expression. The mean relative error in compressibility factor and internal energy is 0.14% and 0.25% respectively, which is a significant improvement over statistical mechanical theories. The EOS was implemented into a thermochemical code in order to optimize gas parameters and evaluate its performance on pure gas data, shock compression and detonation properties. Predicted gas densities, heat capacities and speed of sound for pure gases were generally within experimental uncertainties at pressures up to 1 GPa and temperatures above 300 K. For polar molecules, a simple free energy correction was introduced which greatly improved accuracy at low temperature. Calculated shock Hugoniots showed excellent agreement with experimental values up to 150 GPa and 10 000 K, and the detonation performance was accurately predicted for a number of different types of explosives. [ABSTRACT FROM AUTHOR]

The bar properties (elastic modulus, density, Poisson's ratio, and sound speed) necessary for exploiting bar impact tests were calibrated via two methods called the 1D method (which combines the iterative dispersion correction with 1D approximation) and 3D method (which resorts to the simulation-based reverse engineering of the strain profile in a circular 3D bar). The two methods cross-verified one another for a maraging steel bar with 19.1 mm in diameter. This paper also considers the method of calibrating measured strain and finally presents a method of determining the impact velocity with reference to a reliably measured strain profile for a bar calibrated via the 1D method. [ABSTRACT FROM AUTHOR]

We reveal the specific structural and bonding features that result in anisotropic thermal transport for CsPbBr3 by directional single-crystal measurements and elucidate the bases for the low Debye temperature and speed of sound. This work enhances the research on perovskites and reveals the structural features governing the thermal properties. [ABSTRACT FROM AUTHOR]

Telecommunication of the next generation demands filters that can operate in the 10 GHz range with sufficient bandwidths. For surface-acoustic-wave (SAW) devices this prerequisite translates into high sound velocities and high piezoelectric couplings. Wurtzite AlN on diamond, which exploits the strong piezoelectricity of AlN with the very high SAW velocity of diamond, has been considered a promising platform. A significant boost (up to a factor of 4) of the piezoelectric response can be obtained by alloying AlN with Sc. Here, the main challenge lies in the synthesis of highly-oriented thin (Sc,Al)N films on diamond. In this work, we aim at establishing a platform for SAW devices using plasma-assisted molecular beam epitaxy for the deposition of Sc0.2Al0.8N on diamond. We investigate the structural properties related to SAW generation gearing towards applications at high frequencies. To this end, we prepare (Sc,Al)N thin films on polished polycrystalline diamond wafers and demonstrate the efficient generation of SAW modes with frequencies up to 8 GHz. Systematic studies of the dependence of the SAW velocity and electromechanical coupling coefficient on the Sc0.2Al0.8N film thickness is presented for various SAW modes. Our result demonstrates the potential of this material combination for future application that requires large bandwidth in the ultra-high frequency range. [ABSTRACT FROM AUTHOR]

We reveal the specific structural and bonding features that result in anisotropic thermal transport for CsPbBr3 by directional single-crystal measurements and elucidate the bases for the low Debye temperature and speed of sound. This work enhances the research on perovskites and reveals the structural features governing the thermal properties. [ABSTRACT FROM AUTHOR]

Since Biot's first work on acoustic waves in non-dissipative solid media, it has been known that the group velocity of bulk acoustic waves coincides with the velocity of wave energy transport. The recent studies on these types of velocities for electromagnetic waves reveal that (i) these can differ, and (ii) the superluminal group velocities may exist. The current research demonstrates that in the case of Lamb waves propagating in sandwich clamped–clamped plates, the group velocity can exceed the largest longitudinal bulk wave velocity, and, moreover, the group velocity can be infinitely large, similarly to electromagnetic waves. [ABSTRACT FROM AUTHOR]

The Airy phase is the frequency at which group velocity of a surface acoustic wave (SAW) attains a stationary value. In turn, a stationary value of the group velocity causes SAW to propagate with a lesser attenuation than at other frequencies. At present, no conditions for the appearance of stationary values of the group velocity are known for dispersive modes of Lamb waves propagating in stratified plates. Herein, the closed form solutions are derived for double zero group velocity (ZGV) belonging to the same Lamb mode. It is also found that the double ZGV leads to the appearance of the Airy phase located between the twofold ZGV. The analysis relies on the Cauchy formalism and the exponent fundamental matrix method. [ABSTRACT FROM AUTHOR]

This paper considers the viscous/inviscid Moore–Gibson–Thompson (MGT) equations with memory of type I in the whole space ℝn$$ {\mathrm{\mathbb{R}}}&#x0005E;n $$. For one thing, associating with a new condition on initial data, we derive the optimal L2$$ {L}&#x0005E;2 $$ estimates and the optimal leading term of the acoustic velocity potential for large time, where we analyze different contributions from viscous, thermally relaxing, as well as hereditary fluids on large time asymptotic behavior for the acoustic waves models. For another, by using the multiscale analysis and energy methods in the Fourier space, we demonstrate the L∞$$ {L}&#x0005E;{\infty } $$ inviscid limits (i.e., as the diffusivity of sound tends to zero), which match our Wentzel‐Kramers‐Brillouin (WKB) expansion of the solution. Finally, we give a further application of our results on large time behavior for the nonlinear Jordan‐MGT equation in viscous hereditary fluids. [ABSTRACT FROM AUTHOR]

The underwater environment introduces uncertainty into the acoustic velocity, which affects the performance of traditional direction of arrival (DOA) estimation methods. This research proposes a cascaded neural network based underwater DOA estimate approach to address this issue. In this method, the cascade neural network is composed of a velocity regressor and a velocity classifier. To determine the estimated value of acoustic velocity, the velocity classifier first breaks down the input data into distinct velocity domains. It then regulates the velocity regression process. Then, the array steering matrix predicted by the blind source separation algorithm is utilized to determine the angle, and the acoustic velocity is modiffed by the cascaded neural network. Eventually, it is possible to derive the DOA estimation value under the calculated acoustic velocity. The suggested method has a high estimation accuracy especially when the acousitc velocity is unknown, as shown by the simulation results. [ABSTRACT FROM AUTHOR]

Ultrasonic testing is utilized to ensure weld quality during the fabrication of steel bridges by identifying discontinuities that are classified as either acceptable or rejectable. The classification of a discontinuity can be affected by differences in the acoustic properties of the material under test and the reference standard used for calibration. Differences in wave velocity affect the refracted angle and amplitude of refracted shear waves. As a result, indications can be missed or incorrectly classified, or incorrectly located in the material. The objective of this research study was to characterize the acoustic wave velocities in a sample of contemporary steels to better understand the range over which velocities may vary for common steels. To address this objective, a series of velocity measurements have been conducted for shear waves propagating through different directions in steel plates of different strengths and reported manufacturing processes. The study also examines the loss of signal amplitude that results from changes in the refracted angle of shear waves used for the inspection of welds. Beam splitting that may occur in anisotropic materials and the potential impact on signal amplitudes is also presented. It was shown in the research that relatively small differences in velocity between the material under test and the reference standard cause a loss of sensitivity of the test. Data presented in the paper documents wave velocity and anisotropic ratios for a population of contemporary bridge steels used for the fabrication of steel bridges and an assessment of how velocity differences affect the amplitude of reflected shear waves. [ABSTRACT FROM AUTHOR]

The aim of this study is to address the issue of TDOA/FDOA measurement accuracy in complex underwater environments, which is affected by multipath effects and variations in water sound velocity induced by the challenging nature of the underwater environment. To this end, a novel cooperative localisation algorithm has been developed, integrating the attention mechanism and convolutional neural network-bidirectional gated recurrent unit (CNN-BiGRU) with TDOA/FDOA and two-step weighted least squares (ImTSWLS). This algorithm is designed to enhance the accuracy of TDOA/FDOA measurements in complex underwater environments. The algorithm initially makes use of the considerable capacity of a convolutional neural network (CNN) to extract profound spatial and frequency domain characteristics from multimodal data. These features are of paramount importance for the characterisation of underwater signal propagation, particularly in complex environments. Subsequently, through the use of a bidirectional gated recurrent unit (BiGRU), the algorithm is able to effectively capture long-term dependencies in time series data. This enables a more comprehensive analysis and understanding of the changing pattern of signals over time. Furthermore, the incorporation of an attention mechanism within the algorithm enables the model to focus more on the signal features that have a significant impact on localisation, while simultaneously suppressing the interference of extraneous information. This further enhances the efficiency of identifying and utilising the key signal features. ImTSWLS is employed to resolve the position and velocity data following the acquisition of the predicted TDOA/FDOA, thereby enabling the accurate estimation of the position and velocity of the mobile radiation source. The algorithm was subjected to a series of tests in a variety of simulated underwater environments, including different sea states, target motion speeds and base station configurations. The experimental results demonstrate that the algorithm exhibits a deviation of only 2.88 m/s in velocity estimation and 2.58 m in position estimation when the noise level is 20 dB. The algorithm presented in this paper demonstrates superior performance in both position and velocity estimation compared to other algorithms. [ABSTRACT FROM AUTHOR]

In this work, we construct a new model of compact stars in the presence of anisotropic matter in the Rastall theory of gravity. For this, we considered the anisotropic matter content when formulating the Rastall field equations. Secondly, the Tolman–Oppenheimer–Volkoff (TOV) equation in the context of Rastall theory is formulated. We apply the Finch–Skea ansatz in the static and spherically symmetric geometry to obtain the analytic solution of the derived field equations in the Rastall theory of gravity. We match the internal solution to the corresponding external Schwarzschild space‐time in order to determine the values of the unknown constants involved in the Rastall field equations due to the Finch–Skea ansatz. The resulting model is applied to a few prominent compact stars in order to verify its physical viability. Energy conditions, the TOV equation, stability analysis via sound speeds (radial and transverse in this case), equation of state parameters, mass function, compactness, and surface redshift are some of the analytical expressions that are examined in this inquiry. In order to verify the physical acceptance of the obtained results, we provided a graphical analysis of some necessary analytical expressions. Also, the numerical values of some physical parameters are calculated and are presented in the tabular form to observe the Buchdahl limit and some other important criterion. We note that our model is well consistent with the physical requirements. [ABSTRACT FROM AUTHOR]

Lattice softening is an intricate mechanism utilized to modulate lattice thermal conductivity (κlat). However, experimental observations are often complicated by numerous factors including thermal regimes, elemental matrices, and crystalline topographies, making the fundamental mechanisms complex. In this study, the temperature gradients are meticulously harnessed during phase transitions, both in heating and cooling trajectories, to ascertain that atomic configuration acts as the paramount factor modulating phonon propagation. Within CuTeI, the predilection between the tetragonal (β) and orthorhombic (α) phases is deftly manipulated via specific thermal pathways to a juncture of 273 K. A salient 44% variance in κlat is observed consequent to a singular alteration in the structural disposition of the bridging Cu atoms. Such atomic configurations delineate pronounced differential effects on the transmission dynamics of transverse and longitudinal phonons. The theoretical analysis indicates that the transverse acoustic velocity plays a more pivotal role in dictating κlat than its longitudinal counterpart due to its greater contribution to the Grüneisen parameter. The synergistic interplay of lattice softening and anharmonicity enhancement culminates in an exceptionally diminished κlat in α‐CuTeI, registering a record low κlat of 0.21 W/(m × K) among inorganic materials dominated by phonon–phonon scattering at 273 K. The revelations proffer avant‐garde perspectives for the nuanced modulation of phonon velocities and κlat. [ABSTRACT FROM AUTHOR]

The accurate determination of the ortho-parahydrogen ratio is crucial for various applications involving liquefied hydrogen. At Dresden University of Technology, a speed-of-sound-based measurement setup using a commercial binary gas analyzer was developed in recent years. Through systematic improvements, the setup now allows for very accurate measurements. Perturbations of the speed of sound measurements were reduced significantly by incorporating the gas analyzer into a small dedicated temperature chamber and by optimizing the periphery for minimal gas purity fluctuations. A cross-comparison of the measurement system with a cryostat specifically designed for the production of variable ortho-parahydrogen ratios shows good agreement between the two systems. Although not yet commonly used, speed of sound measurements for ortho-para ratio determination show great potential for several applications. [ABSTRACT FROM AUTHOR]

This study investigates the thermodynamic and transport properties of binary mixtures of 3-pentanol with methyl salicylate, ethyl salicylate, and benzyl salicylate at selected compositions and temperatures from 303.15 K to 313.15 K. The excess molar volume, excess isentropic compressibility, deviation in viscosity, and excess Gibbs free energy of activation of viscous flow were determined from measured values of densities, viscosities, and speeds of sound. The results reveal the strength of hydrogen bonding interactions between the 3-pentanol molecules hydroxyl group and the salicylate derivative molecules’ -OH groups. Furthermore, the Prigogine-Flory-Patterson (PFP) theory is applied to identify the most predominant molecular interaction, and the Jouyban-Acree model results are discussed in terms of mean relative deviation (MRDs) and individual relative deviation (IRD) between calculated and experimental densities, speeds of sound and viscosities as an accuracy criterion [ABSTRACT FROM AUTHOR]

To achieve high-precision wind speed and direction measurements in complex environments, a resonance-state temperature compensation method is proposed based on an ultrasonic resonance principle. This method effectively addresses the issue of sound velocity compensation errors caused by the temperature difference between the internal and external environments when using an internal temperature sensor for temperature compensation. By utilizing an adaptive resonance-state tracking model, the resonance frequency shift issues under varying conditions such as altitude, pressure, and temperature are mitigated. This approach ensures that the resonance frequency is strongly correlated with temperature, enabling temperature compensation through resonance frequency alone, without the need for a temperature sensor. The experimental results indicate that the resonance frequency variation rate with temperature for the resonance-state temperature-compensated ultrasonic resonance wind speed and direction sensor is approximately 0.08 kHz/°C. The wind speed measurement accuracy is ±0.3 m/s (≤15 m/s)/±2.3% (15 m/s~50 m/s), which is superior to the measurement accuracy of traditional ultrasonic wind speed and direction sensors (±0.5 m/s (≤15 m/s)/±4% (15 m/s~50 m/s)). The consistency of wind speed measurement is ≤±0.3%, representing an improvement of approximately 3% compared to ultrasonic resonance wind speed and direction sensors without resonance-state temperature compensation. [ABSTRACT FROM AUTHOR]

In this study, single- and double-parameter empirical equations were produced, and the influences of physical properties on sound speed were assessed, based on the measured data of seafloor sediments obtained in an area near southeastern Hainan Island. The correlation coefficients of the single-parameter empirical equations were found to be greater than 0.65, while those of the double-parameter empirical equations were found to be greater than 0.72, indicating that the double-parameter empirical equations have an advantage in predicting sound speed. According to the sensitivity analysis, mean grain size is the best predictor for sediment sound speed. Furthermore, the empirical equations constructed in this study are a significant addition to sound speed prediction equations and have important application potential in predicting sound speed in the studied area near southeastern Hainan Island. [ABSTRACT FROM AUTHOR]

The strong coupling between carrier and phonon transport in thermoelectric (TE) materials severely limits improvements to the figure of merit (ZT). In this work, an approach is proposed to weaken electron‐phonon coupling, effectively enhancing the TE performance of GeTe. Alloying with Zn4Sb3 reduces excessive carrier concentration (nH), widens the bandgap, and promotes band convergence, synergistically improving charge carrier transport and ensuring a high power factor. Additional Pb doping further optimizes nH, boosting the power factor even more. Moreover, phonon transport is suppressed through Pb doping, as reflected in enhanced acoustic‐optical interactions due to the crossing of optical and acoustic modes, and a reduction in sound group velocity. This reinforced strong phonon scattering, combined with multi‐scale hierarchical nano/microstructures in the matrix, significantly reduces lattice thermal conductivity. As a result, a high ZT of 2.1 is achieved at 753 K in Ge0.9Pb0.1Te+0.9%Zn4Sb3. Alongside optimized mechanical performance, a high power density of 1.46 W cm−2 is realized at a temperature difference of 350 K in the fabricated 7‐pair TE module. The findings demonstrate the effectiveness of a stepwise optimization strategy for developing high‐performance TE materials. [ABSTRACT FROM AUTHOR]

This paper investigates the acoustic streaming effects (ASEs) and mechanisms behind the transmittance of sound in a metallic micro-cavity acoustic black hole (ABH) structure with an abrupt cross-section and examines the sound field flow characteristics inside the micro-cavity ABH under the sound excitation, such as the velocity, acceleration and pressure fields. And the sound transmission mechanisms are characterized by the ASEs which can be obtained by solving Navier–Stokes equations. The numerical results show that the sharp increase in the velocity and acceleration at the ABH tip position is the main reason for the focusing of the sound energy. And the dramatic increase in the tip cross-section reduces the acoustic streaming velocity, which is the main reason for the attenuation of the sound energy. Additionally, the thermoviscous effect of the acoustic boundary layer can also dissipate the low-frequency sound energy. The sound insulation experiment shows that the proposed micro-cavity ABH structure has a sound transmission loss (STL) of over 15 dB in the low-frequency regime. This research reveals the mechanisms of the ASE's work on the sound transmission properties of the micro-cavity ABH and provides new insight into low-frequency sound wave suppression. The ABH structure proposed in this paper has excellent strength, bearing capacity and long lifecycle, so it can be applied in the construction industry through its integrated design of structure and performance. [ABSTRACT FROM AUTHOR]

The fascinating characteristics, such as straightforward and stable crystal structure, and double perovskites are currently popular materials for applications in renewable energy. In our study, we applied CASTEP and DFT, called density functional theory, to theoretically investigate the mechanical, optical, and thermoelectric characteristics of cubic Rb 2 TlCoF 6. Calculations of the compound Rb 2 TlCoF 6 's structural, electrical, optical, mechanical, and thermodynamic properties are made using the GGA-PBE exchange correlational functional and the Fm3m with space group no.225 vol and compound lattice constant are 9.08 Å and 748.613 Å3, respectively. For Rb 2 TlCoF 6 , the measured energy band gaps are 1.45 eV. The mechanical and elastic constants are calculated to confirm the ductile properties of Rb 2 TlCoF 6. The brittle characteristics have been verified using Passion and Pugh's ratios, which are 1.67 and 0.25, according to elastic constants. Vickers compound hardness H v and anisotropy factor "A" are 4.19 and 0.77, respectively. The compounds' optical characteristics reveal significant conductivity and absorption. The compound exhibits high-efficiency photocatalytic activity based on its optical characteristics. Based on mechanical stability, such as Debye temperature, melting temperature, minimum thermal conductivity, average sound velocity, free energy, and other variables, the thermodynamic and structural stabilities are calculated. These materials controlled electrical and other properties make them potentially useful in photocatalytic applications. According to the outcomes, Rb 2 TlCoF 6 is appropriate for photocatalytic water-splitting applications and water deterioration. • To utilize Density Functional Theory (DFT) with mBJ and GGA-PBE methods. • The elastic constants values show that Rb 2 TlCoF 6 is mechanically stable. • The density of state calculations indicates semiconductor. • Studied materials are most suitable for photocatalytic for water splitting applications. [ABSTRACT FROM AUTHOR]

The speed of sound of liquid squalane is measured with the double-path pulse-echo technique, utilizing a piezoelectric quartz (8 MHz) positioned between two reflectors with distinct path lengths. Calibration of the apparatus is carried out with water, for which highly accurate reference data exist. The present experiments with squalane cover the temperature range from 298.15 K to 493.15 K and a pressure from 0.1 MPa to 20 MPa. The total relative expanded ( k = 2 ) uncertainty U r (w) for the speed of sound is estimated to be ±0.1 %. The present data are consistent with literature values, which are, however, only available at ambient pressure. To validate the present speed of sound measurements, the density and isobaric heat capacity are integrated numerically from the sampled data over most of the measurement range, employing rigorous thermodynamic identities. With deviations of about 0.1 %, the resulting density data are favorably compared with literature values. The resulting isobaric heat capacity, for which just a single reference with data at pressures above the ambient exists, deviates by up to 6 %. [ABSTRACT FROM AUTHOR]

Environment-aware underwater acoustic detection and communications demand precise forecasting of the sound speed field (SSF) both temporally and spatially. Toward this goal, recent machine learning models, such as recurrent neural networks and Gaussian process regressions, have outperformed classical autoregressive models. However, from the unified theoretical perspective of conditional distribution learning, there is still significant room for improvement, as existing works have not fully learned the conditional distribution of future SSFs given past SSFs. To address these limitations, in this paper, we leverage the use of diffusion models, the foundation of recent successful deep generative models, such as DALL-E 2 and SORA, to learn the conditional distribution even under limited training data, through careful neural architecture and training strategy design. Our experiments, conducted on real-life South China Sea datasets, confirm that our proposed model outperforms the state-of-the-art baselines in forecasting range-dependent SSFs and the associated underwater transmission losses. Additionally, our model provides reliable confidence intervals that quantify the uncertainties of predictions. [ABSTRACT FROM AUTHOR]

With the rapid development of the marine economy, hydroacoustic positioning technology plays an increasingly important role in marine engineering. The ultra-short baseline (USBL) hydroacoustic positioning system has the advantages of small size, simple operation, and flexible use, and has been widely used. Aiming at the existing USBL acoustic positioning algorithm with low positioning accuracy and complex calculation, a baseline decomposition localization algorithm with arbitrary array structure is proposed. The algorithm is based on the theory of coordinate system transformation, establishes positioning observation equations for each baseline in the base array, and adopts the least squares method to obtain positioning results by selecting different combinations of baselines. The systematic errors of different positioning models themselves are simulated, and then the effects of the three parameter errors, namely, time delay, element coordinates, and sound speed, on the positioning results are analyzed, respectively. Finally, the simulation results and sea trial data show that, compared with the existing algorithms, this algorithm not only simplifies the complicated computation process, but also improves the positioning accuracy and robustness, and has a better application effect. [ABSTRACT FROM AUTHOR]

It is one of the most concerning problems in hydroacoustics to find a method that can calculate the acoustic propagation accurately and adapt to the variation of the seabed. Currently, the one-dimensional spectral method has been employed to address the simplified ocean acoustic propagation model successfully. However, due to the model's application limitations and approximation error, it poses challenges when attempting to solve real-world ocean acoustic fields. Hence, there is a crucial need to develop a direct solution method for the two-dimensional Helmholtz equation of ocean acoustic propagation, without relying on a simplified model. In previous work, we achieved successful solutions for the two-dimensional Helmholtz equation within a rectangular domain, utilizing a collocation-type spectral method. Taking into account the fluctuations in the actual seabed, we introduce a Chebyshev collocation spectral method to directly tackle the two-dimensional ocean acoustic propagation problem, which could solve the case of a seabed with linear variation, sound velocity variation and inhomogeneous medium situation. After comparative verification, the calculation result of the two-dimensional spectral method is more accurate than traditional mature models such as Kraken and COUPLE. By eliminating model constraints and enlarging the solution range, this spectral method holds immense potential in real marine environments. [ABSTRACT FROM AUTHOR]

Multiparametric ultrasound (mpUS) enhances prostate cancer (PCa) diagnosis by using multiple imaging modalities. Tissue-mimicking materials (TMM) phantoms, favoured over animal models for ethical and consistency reasons, were created using polyvinyl alcohol (PVA) with varying molecular weights (Mw). Methods: Four PVA samples, varying in Mw with constant concertation, were mixed with glycerol, silicon carbide (SiC), and aluminium oxide (Al2O3). Phantoms with varying depth and inclusion sizes were created and tested using shear-wave elastography (SWE). An mpUS phantom was developed to mimic prostate tissue, including isoechoic and hypoechoic inclusions and vessels. The phantom was scanned using supersonic ultrasound, strain elastography, and Doppler ultrasound. Validation was performed using radical prostatectomy data and shear-wave elastography. Results: The acoustic properties varied with enhancers like glycerol and Al2O3. Low Mw PVA samples had a speed of sound ranging from 1547.50 ± 2 to 1553.70 ± 2.2 m/s and attenuation of 0.61 ± 0.062 to 0.63 ± 0.05 dB/cm/MHz. High Mw PVA samples ranged from 1555 ± 2.82 to 1566 ± 4.5 m/s and 0.71 ± 0.02 to 0.73 ± 0.046 dB/cm/MHz. Young's modulus ranged from 11 ± 2 to 82.3 ± 0.5 kPa across 1 to 10 freeze-thaw cycles. Inclusion size, depth, and interaction statistically affect the SWE measurements with p-value = 0.056327, p-value = 8.0039 × 10−8, and p-value = 0.057089, respectively. SWE showed isoechoic inclusions, prostate tissue, and surrounding tissue only. The Doppler velocity was measured in three different inner diameters. Conclusion: PVA mixed with enhancer materials creates an mpUS phantom with properties that mimic normal and abnormal prostate tissue, blood vessels, and soft tissue, facilitating advanced diagnostic training and validation. [ABSTRACT FROM AUTHOR]

The effect of light elements (LEs) such as sulfur on the physical properties of liquid iron‐nickel alloy under the earth's outer core conditions is critical for understanding the core composition and dynamics. First‐principles molecular dynamics simulations were employed to model Fe‐Ni‐S liquid with S concentrations in the range of (0–25) atomic percent (at%) at 4050 K and (0–33.33) at% at 5530 K and pressures relevant to the core‐mantle boundary (CMB) and inner core boundary (ICB), respectively. The thermodynamic mixing properties of Fe‐Ni‐S liquid were calculated, showing that the excess volume for Fe‐Ni‐S alloys deviates negatively from ideal mixing by −0.33% at 12.5 at% S at the CMB and −0.35% at 17 at% S at the ICB. Similarly, the excess enthalpy negatively deviated from the ideal mixing by −3.4 kJ/mole and −13 kJ/mole at the similar S concentrations at CMB and ICB, respectively, indicating non‐ideal mixing throughout the outer core. Similar behaviors are observed for isothermal bulk modulus (KT) and seismic velocity. The short‐ and intermediate‐range structures were analyzed and used to explain the non‐ideal mixing behaviors. The results suggest that extrapolations using ideal mixing underestimates the sound velocity by ∼0.14 km/s near CMB and ∼0.10 km/s near ICB, which is significant for constraining the core composition. If S is the only LE, the density at 10–12 wt% S matches the preliminary reference earth model (PREM). The seismic velocity at 12–15 wt% S matches PREM. These results suggest the presence of other LEs in the outer core. Plain Language Summary: This study examines how sulfur mixes with liquid iron‐rich alloys near the conditions relevant to the earth's outer core. We report thermodynamic mixing properties of liquid Fe‐Ni‐S systems near Earth's core‐mantle boundary and inner core boundary conditions. The result suggests a non‐ideal mixing of FeNi‐S melts in the outer core with the excess properties having a negative deviation from the ideal mixing. The liquid structures of Fe‐Ni‐S liquids were analyzed to examine the non‐ideal mixing behavior of sulfur with Fe‐Ni alloy near the earth's core conditions. The effect of non‐ideal mixing on isothermal bulk modulus and compressional sound velocity is significant and affects the estimations of the outer core composition. Our result supports that sulfur cannot be the only light element in the core and the presence of other light elements is required to match the density and sound velocity models derived from seismic data. Key Points: Mixing properties of Fe‐Ni(0–25 at% S) and FeNi(0–33.33 at% S) were calculated near the core‐mantle boundary and inner core boundary, respectivelyNegative excess volume and enthalpy properties were observed, suggesting non‐ideal mixingNon‐ideal mixing has a significant impact on the estimation of geophysical properties of Fe‐Ni‐S alloys near the earth's core conditions [ABSTRACT FROM AUTHOR]

In recent years, a broader perspective has viewed the use of therapeutic environments in healthcare, transforming the hospital's environment into an energizing atmosphere that benefits both employees and patients. Scientists found that exposure to natural elements like nature scenes, sunlight, art, calming colors, and soothing sounds significantly sped up healing and created a more relaxed hospital environment. This research emphasized the importance of healthcare settings' interior design in promoting patient well-being through beneficial distractions. The motivation for this investigation came from the need to develop an understanding of positive distractions in the cancer care environment and showed how this understanding could be used to enhance the space experience to promote health and well-being. This research adopted a mixed-methods approach. First, a qualitative method using a critical review of the literature was used to effectively present, analyze, and synthesize literature from diverse sources, followed by a quasi-experimental research method. This research is intended to focus on the attributes of positive distraction as one of the psychosocially and psychologically supportive healthcare design aspects that evoke positive feelings in children's cancer center experiences. [ABSTRACT FROM AUTHOR]

We present observations of wave steepening and signatures of shock formation during expansion of ultracold neutral plasmas formed with an initial density distribution that is centrally peaked and decays exponentially with distance. The plasma acceleration and velocity decrease at large distance from the plasma center, leading to central ions overtaking ions in the outer regions and the development of a steepening front that is narrow compared to the size of the plasma. The density and velocity change dramatically across the front, and significant heating of the ions is observed in the region of steepest gradients. For a reasonable estimate of electron temperature, the relative velocity of ions on either side of the front modestly exceeds the local sound speed (Mach number M ≳ 1). This indicates that by sculpting steep density gradients, it is possible to create the conditions for shock formation, or very close to it, opening a new avenue of research for ultracold neutral plasmas. [ABSTRACT FROM AUTHOR]

Summary: Bone toxicities are common among paediatric patients treated for acute lymphoblastic leukaemia (ALL) with potentially major negative impact on patients' quality of life. To identify the underlying genetic contributors, we conducted a genome‐wide association study (GWAS) and a transcriptome‐wide association study (TWAS) in 260 patients of European‐descent from the DFCI 05–001 ALL trial, with validation in 101 patients of European‐descent from the DFCI 11–001 ALL trial. We identified a significant association between rs844882 on chromosome 20 and bone toxicities in the DFCI 05–001 trial (p = 1.7 × 10−8). In DFCI 11–001 trial, we observed a consistent trend of this variant with fracture. The variant was an eQTL for two nearby genes, CD93 and THBD. In TWAS, genetically predicted ACAD9 expression was associated with an increased risk of bone toxicities, which was confirmed by meta‐analysis of the two cohorts (meta‐p = 2.4 × 10−6). In addition, a polygenic risk score of heel quantitative ultrasound speed of sound was associated with fracture risk in both cohorts (meta‐p = 2.3 × 10−3). Our findings highlight the genetic influence on treatment‐related bone toxicities in this patient population. The genes we identified in our study provide new biological insights into the development of bone adverse events related to ALL treatment. [ABSTRACT FROM AUTHOR]

Pipe-type cable systems, including high-pressure fluid-filled (HPFF) and high-pressure gas-filled cables, are widely used for underground high-voltage transmission. These systems consist of insulated conductor cables within steel pipes, filled with pressurized fluids or gases for insulation and cooling. Despite their reliability, faults can occur due to insulation degradation, thermal expansion, and environmental factors. As many circuits exceed their 40-year design life, efficient fault localization becomes crucial. Fault location involves prelocation and pinpointing. Therefore, a novel pinpointing approach for pipe-type cable systems is proposed, utilizing accelerometers mounted on a steel pipe to capture fault-induced acoustic signals and employing the time difference of arrival method to accurately pinpoint the location of the fault. The experimental investigations utilized a scaled-down HPFF pipe-type cable system setup, featuring a carbon steel pipe, high-frequency accelerometers, and both mechanical and capacitive discharge methods for generating acoustic pulses. The tests evaluated the propagation velocity, attenuation, and pinpointing accuracy with the pipe in various embedment conditions. The experimental results demonstrated accurate fault pinpointing in the centimeter range, even when the pipe was fully embedded, with the acoustic pulse velocities aligning closely with the theoretical values. These experimental investigation findings highlight the potential of this novel acoustic pinpointing technique to improve fault localization in underground systems, enhance grid reliability, and reduce outage duration. Further research is recommended to validate this approach in full-scale systems. [ABSTRACT FROM AUTHOR]

Error analysis and estimation of thunder source location results is a prerequisite for obtaining accurate location results of thunder sources, which is of great significance for a deeper understanding of the physical process of lightning channel discharges. Most of the thunder source location algorithms are based on the simplified model of the straight-line propagation of acoustic waves to determine the location of the thunder source; however, the acoustic wave is affected by the inhomogeneity of the atmosphere medium in the propagation process and its acoustic ray will be bent. Temperature and humidity are the main factors affecting the vertical distribution of the velocity of sound in the atmosphere, therefore, it is necessary to study the changes in location errors under the models of uniform vertical distribution of temperature only and uniform vertical distribution of humidity only. This paper focuses on the theory of acoustic ray-tracing in neglecting the presence of the wind and the acoustic attenuation and the theoretical derivation of the location error of thunder source inversion for the three models is carried out by using MATLAB R2019b programming. Then, simulation analysis and comparative study on the variation law of thunder source location error with the height of the source, ground temperature, ground humidity, and array position under the three models are carried out. The results of the study show that the maximum location error can be obtained from the straight-line propagation model, the location error obtained from the model of uniform vertical distribution of temperature only is the second, and the location error obtained from the model of uniform vertical distribution of humidity only is the least and can be negligible compared to the first two models. In the trend of error variation, the variation of location error with temperature and humidity is relatively flat in the first two models; however, the variation of location error with the height of the thunder source is more drastic, which can be more than 80%. The location error obtained from the array inversion closer to the thunder source increases linearly with the height of the thunder source, the location error obtained from the more distant array inversion shows a fast-decreasing trend at the height of the thunder source from 500 to 3500 m, and a flat trend above 3500 m. The location error varies relatively smoothly with the height of the thunder source, the ground temperature, and the ground humidity in the model of uniform vertical distribution of humidity only. In addition, the position of the array also has an important effect on lightning location. The further the horizontal distance from the source, the greater the location error will be obtained in the first two models, and when the thunder source is at a low height and detected at a long distance, the location error will be very large, so relevant data should be modified in actual observation. [ABSTRACT FROM AUTHOR]

The properties of small‐amplitude solitary electron acoustic waves in a plasma where the hot electrons take regularized kappa distribution are investigated via the reductive perturbation method. It is found there only exists the sup‐electron‐acoustic rarefactive soliton, the electron acoustic velocity is modified by the regularized kappa distribution. The amplitude and width of the electron acoustic soliton decrease monotonously with the increase of the exponential cutoff parameter of hot electrons. But they vary with respect to the spectral index non‐monotonously. As to the observed parameters in the Earth's inner magnetosphere, the speed, electric field strength, and the width of solitary electron acoustic wave are comparable with the observations. [ABSTRACT FROM AUTHOR]

We investigate models for nonlinear ultrasound propagation in soft biological tissue based on the one that serves as the core for the software package k‐Wave. The systems are solved for the acoustic particle velocity, mass density, and acoustic pressure and involve a fractional absorption operator. We first consider a system that incorporates additional viscosity in the equation for momentum conservation. By constructing a Galerkin approximation procedure, we prove the local existence of its solutions. In view of inverse problems arising from imaging tasks, the theory allows for the variable background mass density, speed of sound, and the nonlinearity parameter in the systems. Second, under stronger conditions on the data, we take the vanishing viscosity limit of the problem, thereby rigorously establishing the existence of solutions for the limiting system as well. [ABSTRACT FROM AUTHOR]

Depending on whether the experiments are quasi-static or fast dynamics, the measured twin boundary velocity values range from zero to the material's sound speed. The twin boundary velocity is not yet predicted theoretically in the continuum mechanics framework. The extension of continual description is provided in the paper by means of internal variables. It is shown that a diffusional slow motion of twin boundaries can be represented using a single internal variable. The dual internal variable technique is employed for the description of the fast dynamics of twin boundaries. [ABSTRACT FROM AUTHOR]

Densities (ρ), speeds of sound (u), and viscosities (η) were derived for three distinct binary mixtures comprising allyl alcohol in conjunction with chlorinated methanes. The Exploration ranged from 303.15 K to 313.15 K, at atmospheric pressure across all composition. The empirical data from the measurements formed the foundational basis for the determination of excess molar volume, excess isentropic compressibility, viscosity deviation and excess Gibbs free energy with the activation of viscous flow. We computed partial molar and infinite dilution properties for each binary system. The results are interpreted in the forming complexes, chemical forces and specific interactions with binary mixtures. The implication drawn from the application of the Jouyban-Acree model are expounded, taking into account the mean relative deviation (MRDs) and individual relative deviation (IRD) between the calculated and experimental densities, speed of sound, and viscosities as a criterion for accuracy criterion. FTIR studies validate experimental findings in investigated mixtures. [ABSTRACT FROM AUTHOR]

Densities (ρ), speeds of sound (u), and viscosities (η) for three binary mixtures of 4-Hydroxy-4-methyl-pentan-2-one with 3-amino-propan-1-ol, 2-amino-2-methyl-propan-1-ol, and 1-amino propan-2-ol were calculated at temperatures ranging from 303.15 to 313.15 K and atmospheric pressure over the entire composition range. Experimental measurements were used to calculate the excess molar volume, excess isentropic compressibility, deviation in viscosity, and excess Gibbs free energy of the activation of viscous flow. Partial molar properties and infinite dilution molar partial properties are also calculated for each binary system. Heteroassociates molecules forming complexes and chemical forces with specific interactions can be discussed from the results. The Prigogine–Flory–Patterson theory is used to identify the most important interaction. The results of the Jouyban–Acree model are discussed in terms of the mean relative deviation and individual relative between the calculated and experimental densities, speed of sound, and viscosities as an accuracy criterion. FTIR studies confirm the experimental findings of the investigated mixtures. [ABSTRACT FROM AUTHOR]

Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of propargyl alcohol (J) with benzyl aldehyde (J1), benzylamine (J2) and benzyl alcohol (J3) components with selected compositions were determined from the measured values of densities (ρ), viscosities (η), and speeds of sound (u) of pure components and their mixtures from 303.15 K to 313.15 K. The effect of various functional groups on the excess properties has been discussed in terms of attractive forces between the components. The results of the Jouyban-Acree model are discussed in terms of the mean relative deviation and individual relative between the calculated and experimental densities, speed of sound, and viscosities as an accuracy criterion.FTIR studies have also been added to confirm the experimental findings of the investigated mixtures [ABSTRACT FROM AUTHOR]