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Many studies have investigated the mass outflows generated when a planar shock transits an imperfect ("defected") metal surface, where the defects are symmetric triangular or sinusoidal grooves. Yet a fundamental question remains unanswered: how does the quantity of outflow mass and its maximum velocity vary as a function of the groove cross-sectional aspect ratio? We identify two sets of missing experiments that must be addressed to answer the question. The aspect ratio (groove depth over width) is equivalently represented by θ , the cross-sectional half angle, or by η 0 k , the amplitude multiplied by an effective wavenumber. Low θ (high η 0 k) grooves comprise the first set of missing experiments, which are necessary to determine the validity of theoretical predictions of the nonlinear regime (η 0 k ≥ 1 , θ < 57.5 °). The second set of missing experiments are those in which the volume of the groove (or equivalently, the axial cross-sectional area) has been held constant as θ or η 0 k are varied. Such experiments are necessary to independently measure the effects of variations in groove volume and groove aspect ratio on the resulting jets. [ABSTRACT FROM AUTHOR]

High-resolution spectroscopy of lead monoxide was performed in a range of 22 400–25 300 cm−1. A new Ω = 1 state located between the a1 and A0+ states was observed, and it is labeled c1. Spectroscopic constants, including the hyperfine interaction coefficient, were determined for the a1 and c1 states. The vibrational levels of these two electronic states are located closely to each other, and the interaction between them causes gradual exchange of electronic state properties in our observation wave number range. Our observation poses a question for the band assignment for the b0− state, which has some resemblance with this c1 state. [ABSTRACT FROM AUTHOR]

The collective density–density and hydrostatic pressure–pressure correlations of glass-forming liquids are spatiotemporally mapped out using molecular dynamics simulations. It is shown that the sharp rise of structural relaxation time below the Arrhenius temperature coincides with the emergence of slow, nonhydrodynamic collective dynamics on mesoscopic scales. The observed long-range, nonhydrodynamic mode is independent of wave numbers and closely coupled to the local structural dynamics. Below the Arrhenius temperature, it dominates the slow collective dynamics on length scales immediately beyond the first structural peak in contrast to the well-known behavior at high temperatures. These results highlight a key connection between the qualitative change in mesoscopic two-point collective dynamics and the dynamic crossover phenomenon. [ABSTRACT FROM AUTHOR]

The (generalized) Derivative Nonlinear Schrödinger (DNLS) equation can be derived as an envelope equation via multiple scaling perturbation analysis from dispersive wave systems. It occurs when the cubic coefficient for the associated NLS equation vanishes for the spatial wave number of the underlying slowly modulated wave packet. It is the purpose of this paper to prove that the DNLS equation makes correct predictions about the dynamics of a Klein-Gordon model with a cubic nonlinearity. The proof is based on energy estimates and normal form transformations. New difficulties occur due to a total resonance and due to a second order resonance. [ABSTRACT FROM AUTHOR]

Empirical rovibrational energy levels are presented for the third most abundant, asymmetric carbon dioxide isotopologue, 16O12C18O, based on a compiled dataset of experimental rovibrational transitions collected from the literature. The 52 literature sources utilized provide 19,438 measured lines with unique assignments in the wavenumber range of 2–12,676 cm−1. The MARVEL (Measured Active Rotational‐Vibrational Energy Levels) protocol, which is built upon the theory of spectroscopic networks, validates the great majority of these transitions and outputs 8786 empirical rovibrational energy levels with an uncertainty estimation based on the experimental uncertainties of the transitions. Issues found in the literature data, such as misassignment of quantum numbers, typographical errors, and misidentifications, are fixed before including them in the final MARVEL dataset and analysis. Comparison of the empirical energy‐level data of this study with those in the line lists CDSD‐2019 and Ames‐2021 shows good overall agreement, significantly better for CDSD‐2019; some issues raised by these comparisons are discussed. [ABSTRACT FROM AUTHOR]

We perform a complete spectral analysis of the linear three-dimensional Boltzmann BGK operator resulting in an explicit transcendental equation for the eigenvalues. Using the theory of finite-rank perturbations, we confirm the existence of a critical wave number k crit which limits the number of hydrodynamic modes in the frequency space. This implies that there are only finitely many isolated eigenvalues above the essential spectrum at each wave number, thus showing the existence of a finite-dimensional, well-separated linear hydrodynamic manifold as a combination of invariant eigenspaces. The obtained results can serve as a benchmark for validating approximate theories of hydrodynamic closures and moment methods and provides the basis for the spectral closure operator. [ABSTRACT FROM AUTHOR]

A novel cooling system for a hot elastic plate is considered by combined utilization of magnetic field, wavy channels and ternary nanofluid. Some applications can be found in electronic cooling, material processing and convective heat transfer control. The elastic object is placed between sinusoidal wavy channels where magnetic field of different strengths is imposed. Ternary nanofluid is used as cooling medium in both channels. Cooling performance assessment is made by various values of Reynolds number (Re, between 250 and 1000), Hartmann number of different channels (Ha, between 0 and 15), amplitude (A, between 0.05 and 0.3) and wave number (N, between 1 and 4) of corrugation, and nanoparticle loading (svf between 0 and 0.03). Entropy generation analysis is also considered. Thermal performance enhancement factor for the maximum and lowest Re configurations in the rigid and elastic object cases are 1.70 and 1.65, respectively. The amount of cooling performance improvement generated by imposing magnetic field at the highest strength is 58.5% and 80% with rigid and elastic objects, respectively. The cooling performance is improved by the wavy form amplitude; however, the wave number relation is non-monotonic. When comparing the wavy channel with the flat one, the increments of thermal performance for stiff and elastic plates are 52% and 57%. Using elastic and stiff objects with nanofluid results in increases in cooling performance of 47.2% and 55.5% when compared to the use of base fluid alone. The best thermal performance is always provided by a rigid item with wavy channels. The least amount of cooling is achieved by using an elastic plate and flat channel. The best options are to increase the magnetic field strength and amplitude of the wavy channel as thermal performance improves and entropy generation drops. [ABSTRACT FROM AUTHOR]

Magnetic field lines in magnetohydrodynamic turbulence are stochastic curves and, therefore, understanding their structure is a difficult problem of theoretical physics. One way to study the properties of such field lines is to perform simulations in which field line equations are solved numerically. In most previous articles studies have been performed in the context of the two-component turbulence model where one assumes a superposition of slab and two-dimensional modes. In the current paper we perform simulations for so-called noisy slab turbulence which is an example for three-dimensional turbulence with small Kubo numbers. We discuss in detail the challenges of the numerical magnetic field creation for this type of turbulence, perform the simulations, and compare our findings with analytical theory. It is demonstrated that a large number of wave modes is needed in order to obtain accurate results. Furthermore, we also show that analytical theories are very accurate for this type of turbulence model. The obtained results will also be useful for the analytical description of energetic particle transport in the considered turbulence model. [ABSTRACT FROM AUTHOR]

Nanofluids have captured the attention of scientists due to their superior thermophysical properties compared to ordinary liquids. Consequently, nanofluids serve as suitable cooling agents applicable to systems requiring swift response to thermal changes, such as vehicle engines. Therefore, the current article scrutinizes the characteristics of heat transfer on the pressure-driven flow of magnetized nanofluid between two curved corrugated surfaces in the presence of heat generation/absorption. Copper oxide nanoparticles (Cu) have been combined with pure water to form a nanofluid called Cu/H 2 O. The geometry of the channel is represented mathematically in an orthogonal curvilinear coordinate system. The corrugation grooves are described by sinusoidal functions with phase differences between the corrugated curved walls. The boundary perturbation method is used to find the analytical solution for the velocity field, temperature field, and volumetric flow rate taking the corrugation amplitude as the perturbation parameter. The impact of dissimilar parameters such as the curvature parameter (0.5 ≤ k ≤ 10) , wave number (1 ≤ α ≤ 3) , magnetic parameter (1 ≤ M ≤ 5) , and wave amplitude (0.1 ≤ ε ≤ 0.8) on the flow fields are analyzed through graphs and discussed in detail. The results show that the peak of the velocity increases with the radius of curvature and the width of the channel for a constant pressure gradient. If we increase the magnetic parameter from 1 to 4, the velocity profile at the specified point decreases by 30 %. If we increase the heat source/sink parameter from 2 to 5, the temperature profile at the specified point increases by approximately 17 %. The flow rate is increased by the corrugations for any phase difference between the corrugated curved walls depending on the corrugation wavenumber and the channel radius of curvature. [ABSTRACT FROM AUTHOR]

Amyloid nanofibrils are long and thin strands with cross β structures associated by hydrogen bonds. These structures can be formed under suitable conditions commonly at low pH and high temperatures. Fibrillated pinto bean protein isolate (FPBPI) was made by heating pinto bean protein at 85°C in an acidic condition while gently stirring at initial protein solution concentrations of 4 mg/mL, 13 mg/mL, and 21 mg/mL. Freeze‐dried FPBPI's physicochemical, structural, and thermal characteristics were assessed, and they were compared with a native pinto bean protein isolate (PBPI) as a control. An increase in Congo red spectral absorption at 544 nm was observed following the fibril formation process. The largest concentration of freeze‐dried fibrillated protein exhibited the highest Congo red spectral absorption. Fibrillar proteins' Fourier transform infrared (FTIR) spectrograms with lower wave numbers were seen than the native protein. For native PBPI, transmission electron microscopy (TEM) images were globular in shape, but they changed to long and curly morphologies in fibrillated proteins. FPBPI has a lower melting enthalpy than native protein when measured by differential scanning calorimetry (DSC). With the rising initial protein content, the enthalpy rose. Concurrently, semicrystalline structure for native and fibrillated pinto bean proteins was revealed by X‐ray diffraction (XRD) findings. As the original protein concentration grew, so did the crystallinity intensity. Water‐holding capacity (WHC) and oil‐holding capacity (OHC) of freeze‐dried FPBPI were higher than those of native protein. So, fibrillation of pinto bean protein helped it to serve as a good thickener in food industries. [ABSTRACT FROM AUTHOR]

Nanocomposites provides a unique opportunity to enhance thermal, mechanical, and waterproof resistance properties of polymer. The effectiveness of these enhancements typically depends on the optimal dispersion and interaction of nanofillers within the polymer matrix. The primary objective of this study is to provide direct chemical evidence for electrostatic interactions between Laponite nanofiller and polyacrylic acid. Samples were prepared by mixing Laponite dispersion and aqueous polyacrylic acid (PAA) that were adjusted to various pH conditions. We observed, an IR peak shift in the carbonyl peak of PAA and Si–O peak of Laponite to lower wave number in nanocomposite, with the maximum shift at pH 7. UV–Vis results also showed a hypsochromic shift in the carbonyl peak of PAA due to the interaction with Laponite. The extent of peak shift in IR, and UV–Vis region for the PAA-Laponite dispersion was found to be influenced by the molar mass of PAA used in the formulation of Laponite-PAA nanocomposite and pH of the medium. These results along with zeta potential measurements strongly suggest that electrostatic forces are in play between deprotonated PAA and the positively charged rim of Laponite in promoting electrostatic interactions between Laponite and PAA. The findings of the study can have a strong bearing on the design of next generation high performance coatings, sealants, and adhesives. [ABSTRACT FROM AUTHOR]

The antibacterial activity of ZnO nanorods (NRs) has been tested for its ability to inhibit the cells of pathogenic bacteria such as Staphylococcus aureus and Salmonella sp. This study aims to increase the antibacterial activity through modification of Mg2+ doped ZnO morphology under sol-gel-hydrothermal synthesis conditions at pH 10. The mechanism of biosynthetic reactions was using enzymatic grooves of the cell phyllosphere isolate of gambir (Uncaria) leaves as a reducing compound and capping agent. The X-ray diffraction (XRD) analysis showed that ZnO and Mg doped ZnO products were wurtzite structures based on intensities 2θ = 31.78°, 34.43°, 36.27° correlated to hkl (100), (002), (101), respectively (ICSD standard −157724). Mg doped ZnO has the same intensity as the control and no impurity intensity was obtained. Scanning electron microscope (SEM) analysis showed nanospheric morphological patterns, while nanorods have a more dominant size distribution in the range of 125–175 nm. Infrared (FT-IR) analysis at wave numbers 401–584 cm−1 showed a Zn-O stretch. Furthermore, powder ultraviolet (UV-DRS) analysis indicated optical properties based on the uptake on blue-shift regions with λmax ≤ 400 nm and had a change in the bandgap (Eg) of 3.37 eV after conversion using Tauc-plot. The results also showed that the greater the concentration of Mg+2 ions, the smaller the bandgap will be, i.e., of 3.13, eV, 3.10, eV, 3.11 eV, and 3.12 eV for 0, 1, 2, and 3%, respectively. On the antibacterial activity against bacteria Gram (+) Staphylococcus aureus and Gram (–) Salmonella typhi., the largest inhibitory zone was found on Gram (–) bacteria at 24 mm. [ABSTRACT FROM AUTHOR]

The vertical shear instability (VSI) is widely believed to be effective in driving turbulence in protoplanetary discs (PPDs). Prior studies on VSI exclusively exploit the reflecting boundary conditions (BCs) at the disc surfaces. VSI depends critically on the boundary behaviours of waves at the disc surfaces. We extend earlier studies by performing a comprehensive numerical analysis of VSI with partially reflecting BCs for both the axisymmetric and non-axisymmetric unstable VSI modes. We find that the growth rates of the unstable modes diminish when the outgoing component of the flow is greater than the incoming one for high-order body modes. When the outgoing wave component dominates, the growth of VSI is notably suppressed. We find that the non-axisymmetric modes are unstable and they grow at a rate that decreases with the azimuthal wavenumber. The different BCs at the lower and upper disc surfaces naturally lead to non-symmetric modes relative to the disc mid-plane. The potential implications of our studies for further understanding planetary formation and evolution in PPDs are also briefly discussed. [ABSTRACT FROM AUTHOR]

AbstractWe explore the possibility for using boundary data to identify sources in elliptic PDEs. Even though the associated forward operator has a large null space, it turns out that box constraints, combined with weighted sparsity regularization, can enable rather accurate recovery of sources with constant magnitude/strength. In addition, for sources with varying strength, the support of the inverse solution will be a subset of the support of the true source. We present both an analysis of the problem and a series of numerical experiments. Our work only addresses discretized problems. The reason for introducing the weighting procedure is that standard (unweighted) sparsity regularization fails to provide adequate results for the source identification task considered in this paper. This investigation is also motivated by applications, e.g. recovering mass distributions from measurements of gravitational fields and inverse scattering. We develop the methodology and the analysis in terms of Euclidean spaces, and our results can therefore be applied to many problems. For example, the results are equally applicable to models involving the screened Poisson equation as to models using the Helmholtz equation, with both large and small wave numbers. [ABSTRACT FROM AUTHOR]

Neutrophils collectively migrate to sites of injury and infection. How these swarms are coordinated to ensure the proper level of recruitment is unknown. Using an ex vivo model of infection, we show that human neutrophil swarming is organized by multiple pulsatile chemoattractant waves. These waves propagate through active relay in which stimulated neutrophils trigger their neighbors to release additional swarming cues. Unlike canonical active relays, we find these waves to be self-terminating, limiting the spatial range of cell recruitment. We identify an NADPH-oxidase-based negative feedback loop that is needed for this self-terminating behavior. We observe near-constant levels of neutrophil recruitment over a wide range of starting conditions, revealing surprising robustness in the swarming process. This homeostatic control is achieved by larger and more numerous swarming waves at lower cell densities. We link defective wave termination to a broken recruitment homeostat in the context of human chronic granulomatous disease. [Display omitted] • Neutrophil swarming is organized by pulsatile, self-extinguishing waves of LTB4 • NADPH-oxidase activation is critical for relay wave self-extinction • Neutrophils adjust the size and number of waves to homeostatically control recruitment • Chronic granulomatosis disease neutrophils generate undamped relay waves that do not extinguish Strickland et al. find that human neutrophils organize pulsatile, self-extinguishing waves of leukotriene B4 to ensure robust homeostatic recruitment. Self-extinguishing waves are dependent on the activity of NADPH oxidase, and deficiency in this pathway leads to a reduced ability to extinguish relay waves. [ABSTRACT FROM AUTHOR]

The usage of potential field data in studying basins has gained recently despite being a reconnaissance tool. High-resolution aeromagnetic data from Niger Delta's Brass and Oloibiri regions were used in this study to qualitatively and quantitatively: examine structures, identify the extension/occurrence of the chain and oceanic fracture zone traversing from the Gulf of Guinea, delineate basement morphology, delineate basement lineament/tectonic trends and then determine depth to basement. On the aeromagnetic map, geomagnetic and diurnal corrections were applied by the Nigerian Geological Survey Agency to remove the effects other than that due to local geology. A project file was created as the gridded data was imported into the Oasis Montaj environment in X (x-coordinate), Y (y-coordinate), and Z (main) channels. Regional-residual separation was initiated on the Z channel for signature decomposition into anomalies of regional and residual extent. Subtlest structural signatures were revealed as the residual was filtered further. This resulted in other field channels from which qualitative maps were generated. Various qualitative grid maps were generated. Faults, folds, dykes, and fracture zones in the ENE-WSW and E-W directions were visible on the qualitative maps. These lineaments hugely affect the area as they act as conduits, synclines, and anticlines, possibly improving economic viability. Fast Fourier Transform (FFT) was applied. This discriminated the signal into its energy and wavenumber component. Consequently, the Log of energy against wavenumber was plotted, and then a line was visually fit unto the high and low spectral energy curves. This art called 2D spectral depth estimate modeled two structural depth sources, Da and Db. The depth to deeper sources, Da, varies from 3 km to 6.8 km, with a 4.5 km average depth, actually the shallow sources are found between 1.5 km and 3.2 km, but with a 2.2 km average depth. Da was imported into Surfer 20 for the depth to the basement map to be generated. The basement map depicts undulations linked to the area. The average depth of 4.5 km emanating from the deeply seated sources is the sedimentary thickness value of the region. The NE-SW and NW-SE lineaments indicate extended Chain/Charcot fracture zones towards the Nigerian Niger Delta region. Due to the appropriate sedimentary thickness discovered and the recessive, NE-SW and NW- SE lineaments traversing from the Biafra Bight towards the region, this suggests that the area still holds a promise and thus hydrocarbon exploration can still be fostered if other conditions are met. [ABSTRACT FROM AUTHOR]

This paper deals with propagation of Rayleigh-type waves in nonlocal inhomogeneous transversely isotropic half-space. From the characteristic equation of wave for the nonlocal inhomogeneous transversely isotropic medium, the existence of the number of surface waves depends on the inhomogeneity of the medium through the number of solutions satisfying the damping condition of the characteristic equation discussed. It has also been concluded that there exist cut-off frequency and escape frequency for the wave propagating in size-dependent materials based on the nonlocal theory. Dispersion equation for the propagation of Rayleigh-type surface waves at the free surface has been derived. Based on the obtained dispersion equation, the effects of the inhomogeneity of material and nonlocality parameter on the Rayleigh wave propagation are considered through some numerical examples. [ABSTRACT FROM AUTHOR]

The wavenumber nonlinearity leads to blurred reconstructed images in spectral‐domain optical coherence tomography (SDOCT). In this work, a wavenumber‐linearisation method without calibration devices is presented, based on the fact that the difference between the phases of adjacent peak and valley points is equal to π$\pi $. The theoretical model is derived, and the efficacy of the method was proven by acquiring SDOCT data from TiO2 phantom and zebrafish. The results exhibit the superior performance of our method. Compared with the linear phase‐based method, the resolution could be improved at least a factor of 2. Compared with the polynomial fitting method, the resolution could also be improved by nearly half. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) technology is widely used in the field of radar imaging. Array sparse optimization reduces the hardware cost of MIMO radar, while virtual aperture and the equivalent phase center (EPC) principle simplify the radar signal model and reduce the computation and complexity of imaging algorithms. However, the application of sparse array structure and the EPC principle produces a non-negligible phase error, which affects the imaging quality. This paper simplifies the MIMO radar signal model based on the phase center approximation, analyzes the phase error generated by this method, and proposes an improved phase error correction method to solve the problem that the target cannot be well-focused at non-reference distance during imaging. In addition, this paper designs a sparse linear MIMO array with a periodic structure, which reduces the number of transmitting and receiving units, system complexity, and hardware costs. The proposed phase correction method was combined with the wavenumber domain algorithm to simulate and experiment on the designed antenna array, and good experimental results were obtained to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This work aims to develop a mathematical model for Love-type wave (LTW) propagation in non-planar non-homogeneous nearly incompressible elastic layered structure with imperfect and sliding interfaces following a geometrical model. Concretely, the geometrical model constitutes two unlike non-homogeneous nearly incompressible elastic materials forming a combination of stratum and substrate, which in turn involve imperfectness at the interface and non-planar boundaries (NPBs). With aid of applicable mathematical techniques, the expressions of displacement components (DCs) of LTW have been determined for both planar boundaries (PBs) and NPBs with imperfect interface. As a special case of the study, the expressions of DCs of LTW have also been deduced for both PBs and NPBs with sliding interface. Further, as an offshoot of the current study, dispersion relations (DRs) of LTW propagating in non-homogeneous and homogeneous nearly incompressible as well as isotropic elastic structures having imperfect, perfect and sliding interfaces have been established and validated with the results present in the literature. For graphical delineation, numerical computation of the DCs and phase velocity (PV) of LTW has been performed. The influences of non-homogeneity parameters, curvature parameters, interfacial parameter and wave number on DCs and PV of LTW have been figured out. It has been revealed that the presence of non-homogeneity in structure has substantial effect on the DCs and PV of LTW. Moreover, a comparative approach has been brought in to study the DCs and PV of LTW in non-homogeneous and homogeneous cases of nearly incompressible elastic structure (NIES) having imperfect and sliding interfaces. [ABSTRACT FROM AUTHOR]

The water content and solvent structure of six poly(vinyl alcohol)-based hydrogels possessing different proportions of borax have been studied as a function of cross-linker concentration. The differing proportions of borax in the matrices cause mesoscopic structural changes in the polymer hydrogel network which lead to differences in water content. The FTIR data show non-monotonic variations in the intensities of the various bands. For the Raman data, the region sensitive to the OH vibrations has been fitted with four Gaussian peaks corresponding to the stretching modes of liquid water. The wavenumber positions of the peaks are dependent on the water content. The non-monotonic behavior of the peak parameters suggests that the structure of entrapped water molecules is dependent on the local mesoscopic structure. From the measurements, cross-linker proportions are seen to affect, both, polymer network and the solvent. [ABSTRACT FROM AUTHOR]

In this paper, wave propagation in functionally graded (FG) porous plates resting on Winkler-Pasternak foundation is studied using a quasi-3D shear deformation theory. The proposed theory has a new displacement field that includes indeterminate integral terms and contains fewer unknown variables taking into account the effect of transverse shear and thickness stretching. The parameters of the elastic foundation are introduced in the present formulation following the mathematical model of Pasternak. In addition, the effect of porosity is studied. The material of the FG plate is inhomogeneous and the material properties are assumed to vary continuously in the thickness direction according to a power law of the volume fraction. The equations governing wave propagation in the plates resting on an elastic foundation are derived using Hamilton's principle. Then, the dispersion relationship between frequency and wave number is solved analytically. A comprehensive numerical result is accomplished to evaluate the effects of the volume fraction index, the porosity, thickness ratio (h/a), and the wave number on the wave propagation in functionally graded porous plates are discussed in detail. [ABSTRACT FROM AUTHOR]

This study experimentally investigated the wave attenuation coefficient and wave number of the heated granite after water cooling (W-C) and air cooling (A-C) treatments. The granite specimens heated to five temperatures (25 °C, 100 °C, 200 °C, 300 °C and 400 °C) were subjected to the W-C and A-C treatments, respectively. The pendulum impact test was performed on the cooled granite at room temperature to obtain the separated stress pulse. The wave attenuation ratio in the cooled granite was investigated. Propagation coefficients (attenuation coefficient and wave number) were introduced to describe the harmonic wave attenuation in the cooled granite. The effects of W-C and A-C treatments on the attenuation coefficient and wave number were discussed. The results show that the P-wave velocity decreases as temperature increases, while the wave attenuation ratio increases as temperature increases. The P-wave velocity of the granite after the W-C treatment is smaller than that of the granite after the A-C treatment. The wave attenuation ratio, attenuation coefficient and wave number of the stress pulse in the granite after the W-C treatment are larger than those of the stress pulse in the granite after the A-C treatment. The differences of P-wave velocity, wave attenuation ratio, attenuation coefficient and wave number after two cooling treatments increase as temperature increases. [ABSTRACT FROM AUTHOR]

The work reported in this paper addresses two aspects. In the first part, numerical simulations are conducted to examine the impact of magnetic equilibrium shaping (elongation and triangularity), on both conventional Ion Temperature Gradient (ITG) modes and Short Wavelength ITG modes. This analysis is performed considering the experimental profiles and parameters of the ADITYA-U tokamak, employing the nonlinear global gyrokinetic Particle-in-Cell code ORB5. The linear and nonlinear collisionless electrostatic simulation of these modes are carried out with kinetic ions and adiabatic electrons. From the linear results, it has been observed that the magnetic equilibrium shaping slighty reduced the growth rates and widened the spectrum, and the maxima of growth rate curve is shifted to higher toroidal wave number. We find that the heat flux is reduced by a significant ≃ 35 % for the true circular magnetohydrodynamic magnetic equilibrium as compared to ad hoc concentric circular equilibrium reported in Singh et al (2023 Nucl. Fusion 63 086029). A further ≃ 10 % reduction in the heat flux is seen with magnetic equilibrium shaping. In the second part, linear collisionless electrostatic simulation studies of ITG coupled with fully kinetic electrons (both trapped and passing electrons are treated kinetically) using a drift-kinetic ordering is performed. It can be seen from the linear results that, in presence of kinetic electrons, the growth rate and real frequency of the ITG mode are increased significantly for ADITYA-U parameters and a mode propagating in the electron diamagnetic direction is identified at high toroidal wavenumbers. [ABSTRACT FROM AUTHOR]

An analysis of the propagation behavior of Rayleigh wave has been conducted in an anisotropic layer, such as reservoir rocks overlying a sandy medium. The layer and lower half-space interface have been considered imperfect, whereas a corrugated upper boundary has been assumed. A closed relation of phase velocity and wave number has been obtained as a determinant form. For the numerical interpretation of results, reservoir rocks of triclinic type have been modeled. Some special cases are taken into account. The study examines the simultaneous simulated results of several physical parameters and illustrates the effects of thickness, sandiness parameter, phase velocity, corrugation amplitude, corrugation wavelength, and imperfect Rayleigh wave interface distribution in the structure under consideration, which was created using Mathematica 7. For variations in wave number and phase velocity, diagrams are drawn. [ABSTRACT FROM AUTHOR]

Analysis of equations of motion by Moczo et al. (2022) led to the conclusion that the discrete (grid) representation of the heterogeneous medium must be wavenumber bandlimited up to the Nyquist frequency. This is a consequence of the spatial discretization. Mittet (2021a) reported that if the discrete grid model of medium coincides with the true medium up to some wavenumber, the simulated wavefield is accurate only up to a half of this wavenumber. Here, we present results of the systematic and comprehensive analysis focused on the principal limits of accuracy of numerically simulated wavefields. First, we analyze wavenumber spectra of (1) exact wavefields in a heterogeneous elastic medium, (2) wavenumber bandlimited wavefields, and (3) spatially discretized wavefields. Then, we derive spatial dependence of the frequency spectrum of waves generated by a finite source, and perturbing wavefields due to a small perturbation of the medium and due to a small wavenumber bandlimited perturbation of the medium. We analyze an interaction of an incoming wave with the medium perturbation through a change of phase difference and through wavenumber spectra. We draw conclusions on the wavenumber limitation of wavefields in the wavenumber bandlimited heterogeneous medium. We numerically verify the fundamental finding using exact solutions. The main consequence for the finite-difference (FD) modeling based on spatial discretization of the computational domain is: Due to spatial sampling, the medium must be wavenumber limited up to the Nyquist frequency. Then, the wavefield should not be sampled by less than four spatial grid spacings per shortest wavelength to obtain sufficiently accurate results. This applies to any heterogeneous FD scheme. [ABSTRACT FROM AUTHOR]

Ship-based measurements of sea spray aerosol (SSA) gradient fluxes in the size range of 0.5–47 µm in diameter were conducted between 2009–2017 in both the Baltic Sea and the North Atlantic Ocean. Measured total SSA fluxes varied between 8.9 × 10 3 ± 6.8 × 10 5 m -2 s -1 for the Baltic Sea and 1.0 × 10 4 ± 10 5 m -2 s -1 for the Atlantic Ocean. The analysis uncovered a significant decrease (by a factor of 2.2 in the wind speed range of 10.5–14.5 m s -1) in SSA fluxes, with chlorophyll a (chl a) concentration higher than 3.5 mg m -3 in the Baltic Sea area. We found statistically significant correlations for both regions of interest between SSA fluxes and various environmental factors, including wind speed, wind acceleration, wave age, significant wave height, and wave Reynolds number. Our findings indicate that higher chl a concentrations are associated with reduced SSA fluxes at higher wind speeds in the Baltic Sea, while the influence of wave age showed higher aerosol emissions in the Baltic Sea for younger waves compared to the Atlantic Ocean. These insights underscore the complex interplay between biological activity and physical dynamics in regulating SSA emissions. Additionally, in both measurement regions, we observed weak correlations between SSA fluxes and air and water temperature and between SSA fluxes and atmospheric stability. Comparing the Baltic Sea and the North Atlantic, we noted distinct emission behaviors, with higher emissions in the Baltic Sea at low wave age values compared to the Atlantic Ocean. This study represents the first comparative analysis of SSA flux measurements using the same methodology in these contrasting marine environments. [ABSTRACT FROM AUTHOR]

Purpose: To study implant lead tip heating because of the RF power deposition by developing mathematical models and comparing them with measurements acquired at 1.5 T and 3 T, especially to predict resonant length. Theory and Methods: A simple exponential model and an adapted transmission line model for the electric field transfer function were developed. A set of wavenumbers, including that calculated from insulated antenna theory (King wavenumber) and that of the embedding medium were considered. Experiments on insulated, capped wires of varying lengths were performed to determine maximum temperature rise under RF exposure. The results are compared with model predictions from analytical expressions derived under the assumption of a constant electric field, and with those numerically calculated from spatially varying, simulated electric fields from body coil transmission. Simple expressions for the resonant length bounded between one‐quarter and one‐half wavelength are developed based on the roots of transcendental equations. Results: The King wavenumber for both models more closely matched the experimental data with a maximum root mean square error of 9.81°C at 1.5 T and 5.71°C at 3 T compared to other wavenumbers with a maximum root mean square error of 27.52°C at 1.5 T and 22.01°C for 3 T. Resonant length was more accurately predicted compared to values solely based on the embedding medium. Conclusion: Analytical expressions were developed for implanted lead heating and resonant lengths under specific assumptions. The value of the wavenumber has a strong effect on the model predictions. Our work could be used to better manage implanted device lead tip heating. [ABSTRACT FROM AUTHOR]

ABSTRACT EMEC waves driven by kinetic anisotropies and suprathermal particles are expected to play an important role at dissipative scales in the solar wind and planetary magnetospheres. Moreover, the correlation of EMEC waves with electric field magnitude and direction can be a tool to probe the inner magnetosphere. Thus, in this manuscript, we present the study of EMEC waves driven by temperature anisotropy in bi‐Kappa distributed space plasmas in the presence of a parallel DC electric field. The dispersion equation bearing the influence of electric field and suprathermal particles followed by the analytical expressions for wave frequency and wave growth rate is derived. The general dispersion equation is solved numerically to unveil the effect of suprathermal particles, temperature anisotropy, and the magnitude of the electric field on growth rate as well as the domain of unstable wave numbers, and the obtained numerical outcomes are compared with those of the bi‐Maxwellian model. Moreover, the maximum growth rates for EMEC waves have also been obtained. [ABSTRACT FROM AUTHOR]

In this work, we seek to investigate the dynamics of bright soliton in a chain of coupled pendulum pairs. After deriving the linear dispersion relation from the equation of the model, we find that among the obtained modes, the fast mode is the one on which we are going to be focused. Since the discrete simultaneous equation describing the dynamics of the model has not been extensively studied in the literature, we assume that the two lines of the model are proportional to each other. We use the rotating wave approximation method to derive a NLS equation governing the propagation of waves in the network. Depending on the choice of wave number, we deduce that the system supports bright and hole-soliton solutions. We use the obtained bright soliton as the initial condition for numerical computation, which demonstrates the significant role of the transverse coupling parameter in the system. That is, it affects the behavior of the forward-bright soliton generated in the system. The lattice allows gain and loss phenomena during the propagation of the waves. [ABSTRACT FROM AUTHOR]

A series of chromium-substituted cadmium post-spinel ferrites CdCr x Fe 2-x O 4 (x = 0.0, 0.1, 0.3, 0.5) have been synthesized through the sol-gel auto-ignition method. The structural, vibrational, dielectric, magnetic, and microwave absorption properties of β -spinel ferrites through modern techniques which include X-ray diffraction, FTIR Spectroscopy, and Vector network analyzer. X-ray diffraction technique was used for structural investigation which confirmed the monophasic orthorhombic structure of prepared samples and a detailed study revealed that no impurity/additional phases were detected. Crystallite size and strain were extracted via the Williamson-Hall (W–H) method and Size strain plot (SSP). Vibrational spectroscopy (FTIR) successfully verified the spectral qualities of studied ferrites as measured wave number ranges between 400 and 600 cm−1. X-ray photoelectron spectroscopy verified that all metal ions exist and possess the corresponding electronic states. Electrical properties have been investigated at the microwave region (1 MHz – 6 GHz). The conduction mechanism has been studied via Johnscher power law. The Cole-Cole plot of all the samples consisting of two semicircles corresponding to grain and grain boundaries described the increasing conduction phenomena. In the present research, stable dielectric constant, dielectric loss, enhanced magnetic characteristics, and minimum reflection loss (−31.9 dB) make these CdCr x Fe 2-x O 4 nano-crystallites most suitable candidates for highly dense and high-frequency microwave devices for EMI shielding material. [ABSTRACT FROM AUTHOR]

In this study, the performance of 24 Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating the dynamic processes of Arctic sea ice concentration (SIC)‐ and El Niño‐Southern Oscillation (ENSO)‐ forced teleconnection during winter is subjectively and objectively evaluated. The Arctic SIC‐forced teleconnection is associated with a warm Arctic‐cold Eurasian pattern of surface temperature (T2m), a low Arctic‐high Eurasian pattern of sea level pressure (SLP), and a southeastward propagating wave‐train originating from Arctic in the upper troposphere. The ENSO‐forced teleconnection is associated with a poleward propagating wave‐train originating from tropical Pacific in the upper troposphere, a low North Pacific‐high Arctic pattern of SLP, and a cold North Pacific‐warm Greenland pattern of T2m. The metrics of Taylor skill scores and Distance between indices of simulation and observation (DISO) are used to objectively and quantitatively evaluate the performance of models. The results of subjective and objective evaluation are essentially consistent. The CanESM5, MPI‐ESM1‐2‐HR, EC‐Earth3, and MRI‐ESM2‐0 models have the best performance in simulating the Arctic SIC‐forced teleconnection. The CESM2, ACCESS‐CM2, NESM3, NorESM2‐MM, CAS‐ESM2‐0, MRI‐ESM2‐0 models have the best performance in simulating the ENSO‐forced teleconnection. The two best‐performing multi‐model ensembles well reproduce the dynamic processes of the Arctic SIC‐ and ENSO‐ forced teleconnection. The diversity of model performance is attributed to the different skills of different models in simulating the interannual variability of Arctic SIC, the anomalous deep warm high over the Barents‐Kara Seas, the interannual variability of tropical Pacific SSTs, and the wave number of poleward propagating Rossby waves. Plain Language Summary: The connection between Arctic and tropical climates has an important influence on the climate in Northern Hemisphere. The Arctic sea ice‐driven teleconnection may induce increased cold surges toward the low latitude regions of East Asia, while the El Niño‐Southern Oscillation (ENSO)‐driven teleconnection may induce increased temperatures over northern North America and Greenland. The Coupled Model Intercomparison Project Phase 6 (CMIP6) models consists of state‐of‐the‐art numerical models that are widely used in climate simulation and prediction. Hence, it is important to understand the performance of these models in simulating the dynamic processes of Arctic‐tropical climate connection and the potential reasons. In this study, the dynamic processes in ocean‐atmosphere associated with the Arctic sea ice‐ and ENSO‐ driven teleconnection are first analyzed using observed/re‐analysis data. The performance of 24 CMIP6 models in simulating the dynamic processes of Arctic sea ice‐ and ENSO‐ driven teleconnection is then subjectively and objectively evaluated. The results indicate a diversity of performance in these models. This diversity are mainly caused by the different skills of models in simulating the interannual variability of SIC and ENSO as well as the associated atmospheric circulation anomalies. Key Points: The performance of CMIP6 models has a diversity in simulating the dynamic processes of Arctic‐tropical climate connectionBest‐performing multi‐model ensembles with good skill in simulating dynamic processes of Arctic‐tropical climate connection are selectedThe diversity in performance of models are affected by the skill of models in simulating the interannual variability sea ice and SSTs [ABSTRACT FROM AUTHOR]

This study experimentally demonstrates the coexistence and transition between weak and strong wave turbulence during the interaction of acoustic waves and turbulent flows. We identify conditions under which different wave turbulence regimes occur based on the wave number of the turbulent flow and acoustic waves. As the sound frequency increases, strong wave turbulence dominates, requiring a specific scaling factor to reconcile the spectra with the weak turbulence theory. Our analysis using the wave turbulence framework is confirmed by experimental results, providing deep insights into the complex interaction between acoustics and turbulence. [ABSTRACT FROM AUTHOR]

The traditional specific storage coefficient (Ss) was defined under two assumptions. One is that aquifer rock deforms only in the vertical direction, and the other is that the average rock stress remains unchanged. Consequently, Ss is irrelevant to the shear modulus of rock (G). In this paper, the Biot theory is used to derive a new specific storage coefficient (Ss∗) with the natural deformation of rock. Ss∗ appears to be relevant to G. Compressed glass beads and Berea sandstone are used for illustration. At frequencies lower than 10 kHz, the equation of groundwater flow with Ss∗ yields the same phase velocity and quality factor as the Biot theory, and therefore, it is capable of accurately predicting fluid pressure diffusion in the low‐frequency regime. The results also show that Ss is 16%–17% higher than Ss∗. In conclusion, the latter one is superior to the former in its consistency with the Biot theory and unconstraint by the aforementioned two assumptions. [ABSTRACT FROM AUTHOR]

High humidity combined with high temperature decreases the human body's capability to dissipate heat, causing serious health issues. While increased attention has been paid to changes in humid‐heat extremes under the current climate and in the future, the causes of near‐surface humid‐heat extremes over the Yangtze River Delta region are still unclear. Here we investigate the relationships between quasi‐stationary waves (QSWs), which are atmospheric Rossby waves with phase speed close to zero, and humid‐heat extremes over the Yangtze River Delta region during the summer from 1959 to 2021. Additionally, the potential physical processes that link them are also explored. We find that the QSWs with wavenumber 1–8 present different vertical structures: Wave 1–2 are baroclinic, while Wave 3–8 are barotropic. Wave 1, 3, 5, 6, 7 and 8 show phase‐locking behaviour. When the amplitudes of Wave 1, 3, 5 and 6 are higher, the frequency of humid‐heat extremes near the surface at specific locations tends to be higher than the norm. The high‐amplitude waves in different wavenumbers modulate near‐surface temperature and/or humidity in various ways, ultimately resulting in anomalously intensive humid‐heat extremes. [ABSTRACT FROM AUTHOR]

Pressure-driven movement is a fundamental concept with numerous applications in various industries, scientific disciplines, and fields of engineering. Its proper execution is vital for promoting revolutionary innovations and providing solutions in numerous sectors. Therefore, this article scrutinizes the pressure-driven flow of a magnetized Jeffrey fluid between two curved corrugated walls. The geometry of the channel is represented mathematically in an orthogonal curvilinear coordinate system. The corrugation grooves are described by sinusoidal functions with phase differences between the corrugated curved walls. The boundary perturbation method is used to find the analytical solution for the velocity and temperature taking the corrugation amplitude as the perturbation parameter. Furthermore, the volumetric flow rate, skin friction coefficient, and local Nusselt numbers are precisely calculated numerically for a variety of parameters, with the results presented comprehensively in tabular form. The impact of dissimilar parameters, such as the curvature parameter, wave number, magnetic parameter, Darcy number, thermal radiation, heat source/sink parameter, Jeffery fluid parameter, and amplitude parameter, on the flow fields is analyzed through graphical and tabular forms and discussed in detail. The results show that the velocity profile increases due to the curvature parameter and the Jeffrey fluid parameter. However, it decreases due to the magnetic parameter. The temperature distribution rises with the thermal slip and heat source/sink parameters. Meanwhile, it declined for the radiation parameter and the curvature parameter. The model can be used to simulate blood flow in arteries with varying geometries and magnetic fields, aiding in the study of cardiovascular diseases and the design of medical devices such as stents. [ABSTRACT FROM AUTHOR]

The non-stationary Karpman–Washimi ponderomotive force and self-generated magnetic field in an unmagnetized system are investigated in the context of nonextensive distribution based on the kinetic theory. The ponderomotive force, magnetization, and radiation power are obtained as functions of the nonextensive parameter q, wave frequency, and wave number. It is shown that the presence of high-velocity electrons leads to an increase in temporal and spatial variation parts of ponderomotive force, magnetization, and radiation power. Furthermore, the results indicate that the self-generated magnetic field driven by the Karpman–Washimi ponderomotive force primarily manifests as small-scale and low-frequency magnetic field. [ABSTRACT FROM AUTHOR]

We perform the modulation instability analysis of the 2D and 3D nonlinear Klein–Gordon equation. The instability region depends on dispersion and wavenumbers of the plane wave. The N -breathers of the nonlinear Klein–Gordon equation are constructed directly from its 2 N -solitons obtained in history. The regularity conditions of breathers are established. The dynamic behaviors of breathers of the 2D nonlinear Klein–Gordon equation are consistent with modulation instability analysis. Furthermore, by means of the bilinear method together with improved long-wave limit technique, we obtain general high order rogue waves of the 2D and 3D nonlinear Klein–Gordon equation. In particular, the first- and second-order rogue waves and lumps of the 2D nonlinear Klein–Gordon equation are investigated by using their explicit expressions. We find that their dynamic behaviors are similar to the nonlinear Schrödinger equation. Finally, the first-order rational solutions are illustrated for the 3D nonlinear Klein–Gordon equation. It is demonstrated that the rogue waves of the 2D and 3D nonlinear Klein–Gordon equation always exist by choosing dispersion and wavenumber of plane waves. [ABSTRACT FROM AUTHOR]

The basic design of a Love wave (LW) bio-sensor contains the loading of a viscoelastic liquid on top of a layered structure with distinct viscoelastic properties. Changes in the characteristics of the propagating acoustic wave caused by biochemical interactions at the sensing area can be detected at the output Inter digital transducer (IDT). The propagation of the anti-plane (AP) wave is discussed in this work in a layered structure of piezo-flexo-electric (PFE) layer bonded with a PFE half-space having a soft reinforced layer at the interface. The free surface of the PFE layer is loaded with viscous liquid. The viscosity of the loaded liquid introduces losses and results in the damping of the wave. For the formulation of the problem with interface energy, the Gurtin–Murdoch approach is used. Using suitable conditions, a dispersion relation for propagating waves is derived in complex form. On separating the dispersion relation in real and non-real parts, the expressions relating the phase and damp velocities with wave number are derived. The obtained theoretical results are portrayed for the numerical data of PFE materials and distinct data of the interface layer. The obtained results are validated with pre-existing literature. [ABSTRACT FROM AUTHOR]

The design of wavy structures and their mechanical implications on artificial blood vessels (ABVs) have been insufficiently studied in the existing literature. This research aims to explore the influence of various wavy geometric designs on the mechanical properties of ABVs and to establish a foundational framework for advancing and applying these designs. Computer-aided design (CAD) and finite element method (FEM) simulations, in conjunction with physical sample testing, were utilized. A geometric model incorporating concave and convex curves was developed and analyzed with a symbolic mathematical tool. Subsequently, a total of ten CAD models were subjected to increasing internal pressures using a FEM simulation to evaluate the expansion of internal areas. Additionally, physical experiments were conducted further to investigate the expansion of ABV samples under pressure. The results demonstrated that increased wave numbers significantly enhance the flexibility of ABVs. Samples with 22 waves exhibited a 45% larger area under 24 kPa pressure than those with simple circles. However, the increased number of waves also led to undesirable high-pressure gradients at elevated pressures. Furthermore, a strong correlation was observed between the experimental outcomes and the simulation results, with a notably low error margin, ranging from 19.88% to 3.84%. Incorporating wavy designs into ABVs can effectively increase both vessel flexibility and the internal area under pressure. Finally, it was found that expansion depending on the wave number can be efficiently modeled with a simple linear equation, which could be utilized in future designs. [ABSTRACT FROM AUTHOR]

This paper explores plasma wave modes using the extended magnetohydrodynamics (XMHD) model, incorporating Hall drift and electron inertia effects. We utilize the geometric optics ansatz to study perturbed quantities, with a focus on incompressible systems. Our research concludes with the derivation of the dispersion relation for incompressible XMHD and the associated eigenvector solutions, offering new perspectives on plasma wave behavior under these extended scenarios. The dispersion relation shows distinct ion cyclotron and whistler wave branches, with characteristic saturation at the ion and electron gyrofrequencies, respectively. Comparisons between Hall MHD and XMHD demonstrate that XMHD provides a more accurate representation of plasma dynamics, especially at higher wave numbers, bridging the gap between simplified models and comprehensive two-fluid descriptions and smoothing out singularities present in Hall MHD solutions and capturing more physics of the full two-fluid model. [ABSTRACT FROM AUTHOR]

Accurate calculations of ocean acoustic propagation are of significant importance in various aspects such as marine environmental monitoring, oceanic communication, and navigation. Various mature simplified models have been developed, such as the normal mode model, parabolic approximation model, and wavenumber integration model. The above-mentioned models and algorithms all have limitations, namely, "applicable domain," which restrict their range of application. Instead of simplifying model, the algorithm described in this article aims at solving the Helmholtz equation, which governs ocean acoustic propagation. It solves the ocean acoustic propagation without being constrained by model application conditions and has a wide range of applications, which is a versatile method for solving acoustic propagation. The algorithm utilizes Chebyshev tau matrix method to directly solve the two-dimensional acoustic Helmholtz equation, which could solve the situation of uneven media within irregular domain, addressing the issue of traditional spectral method being unsuitable for non-rectangular domain. Compared with the mature programs, the new spectral method offers higher computational accuracy and is capable of calculating acoustic propagation in more complex ocean environments. [ABSTRACT FROM AUTHOR]

This study experimentally optimizes the mixing of a turbulent jet at Reynolds number 10 000 with the surrounding air by targeted shear layer actuation. The forcing is composed of superposed harmonic signals of different azimuthal wavenumber m generated by eight loudspeakers circumferentially distributed around the nozzle lip. Amplitudes and frequencies of the individual harmonic contributions serve as optimization parameters, and the time-averaged centerline velocity downstream of the potential core is used as a metric for mixing optimization. The actuation is optimized through Bayesian optimization. Three search spaces are explored—axisymmetric forcing, m = 0, superposed axisymmetric and helical forcing, m ∈ { 0 , 1 } , and axisymmetric actuation combined with two counter-rotating helical modes, m ∈ { − 1 , 0 , 1 }. High-speed particle image velocimetry (PIV) is employed to analyze the jet response to the optimized forcing. The optimization processes are analyzed by persistent data topology. In the search space of axisymmetric excitation, the routine identifies an actuation at the natural frequency of the flow to be most efficient, with the centerline velocity being decreased by 15%. The optimal solutions in both the two-mode and three-mode search space converge to a similar forcing with one axial and one helical mode combined at a frequency ratio of around 2.3. Spectral analysis of the PIV images reveals that for the identified optimal forcing frequencies, a non-linear interaction between forced and natural structures in the jet flow is triggered, leading to a reduction in centerline velocity of around 35%. The topology of the most complex search space from the discrete data reveals four basins of attractions, classified into three forcing patterns including axisymmetric, axisymmetric-helical, and axisymmetric-flapping. Two deep basins are related to the optimal pattern found as axisymmetric-helical, and the others are shallower. [ABSTRACT FROM AUTHOR]

This study examines the influence of the structure of the combustor on the propagation of rotating detonation waves (RDWs) of cracked kerosene gas (CKG) by using oxygen-rich air, with mass fractions of oxygen of 36% and 48%, as the oxidant while maintaining stable values of the state parameters of CKG. The experimental results showed that the structure of the combustor played a key role in the initiation and stable propagation of CKG, and suitable values of its width and the width of its outlet promoted the stable self-sustained propagation of the RDWs. Combustors of 8 and 14 mm width failed to initiate with 36% oxygen-rich air and without blockage ratio. In the combustors of 20 and 26 mm width, as the blockage ratio increased, the modes of propagation of the RDW included a single stable RDW, intermittent single RDW, and four, six, and eight counter-rotating RDWs. With the further increase in the blockage ratio, the reflected shock wave at the end of the combustor was enhanced, resulting in an increase in the number of RDW wave heads. As a result, the height of the fresh fuel layer was decreased, the mixing time was decreased and led to a decrease in the RDW velocity. The increase in the width of the combustor was conducive to the radial and axial diffusion of fuel and oxidizer in the combustor, which led to an obvious increase in the propagation velocity of RDW. In the 26 mm width combustor, the maximum RDW velocity is 1769 m/s. [ABSTRACT FROM AUTHOR]

Faraday instability of viscous liquid films with Maxwell–Cattaneo (MC) heat flux on an infinite, heated horizontal substrate subject to vertical time-varying periodic vibration is investigated theoretically. The MC effect means that the response of the heat flux to a temperature gradient obeys a relaxation time law rather than a classical Fourier time law. Applying the classic Floquet theory to linear analysis, a recursive relation is obtained. When considering the MC effect, a new phenomenon appears at a large wave number k. The neutral stability curves branch new tongues that turn left rather than right as before, but the tongues still move up and right as the wave number increases. Furthermore, typical harmonic (H) and subharmonic (SH) alternation behavior continues to exist. Interestingly, the first tongue of a branch is H or SH, implying that there is a transition following the branches. However, near the critical wave number kc of a branch, the SH and H almost overlap. As Cattaneo number C increases, the tongue-like unstable zones of branches become wider, and the critical wave number kc of the appeared branch becomes small. As the driving frequency ω decreases, the branch tongues become elongated and the critical wave number kc of the appeared branch becomes small. [ABSTRACT FROM AUTHOR]

A theoretical and numerical investigation of electrokinetic flow is performed in a nanochannel with the charged symmetric corrugated surfaces. The perturbation and numerical solutions of electrokinetic flow variables are given, and the effects of corrugation geometry, such as wave amplitude and wave number, on the electrokinetic flow characteristics are systematically examined. The results show that the electrokinetic flow recirculation may occur easily at wave crest due to the electroviscous effect. The velocity profile is strongly dependent on wave number, but the maximum or minimum velocity may be insusceptible to wave number. Furthermore, the distributions of streaming potential and energy conversion efficiency are also investigated. We find that, for some special geometry of corrugations, the streaming current and conversion efficiency obtained from the present corrugated nanochannel are higher than that from the smooth nanochannel. Specially, when the dimensionless wave number is 0.5/π, the magnitude of streaming potential is enhanced about 29% at δ = 0.5 and the peak value of conversion efficiency is enhanced about 2% at δ = 0.1. We believe that the optimal corrugation geometry parameters can be of benefit in designing a microfluidic device with higher streaming current and conversion efficiency. [ABSTRACT FROM AUTHOR]

Unlike acoustic metasurfaces that rely solely on phase gradients, acoustic metagratings (AMs) operate based on both phase gradients and grating diffraction, thus further extending the generalized Snell's law (GSL). In particular, AMs can achieve reversal of refraction and reflection based on the parity of the number of wave propagations inside the AMs. So far, discussions of this GSL extension have largely been applied to one-dimensional periodic AMs, while the designs of two-dimensional (2D) periodic AMs and their performance in three-dimensional (3D) space have been quite limited. Here, we study the GSL extension in 3D space and experimentally demonstrate a series of functional 2D periodic AMs. The designed AMs can achieve sound refraction/reflection under any incidence angle in 3D space, without restrictions to certain critical ranges; adjusting incident angles only enables the reversal of refraction and reflection. Additionally, we demonstrate two types of dual-layer sound lenses based on two AMs, whose reversal of refraction and reflection can be realized by simply attaching or separating the two AMs. Our work paves the way to complex 3D wavefront manipulation of AMs, which may find potential use in practical acoustic devices. [ABSTRACT FROM AUTHOR]

The background differences in water content of different samples have a very strong influence on the robustness of near-infrared spectroscopy (NIRS). For this reason, this study simulated typical biological water matrix samples with formulated hemoglobin (Hb), glucose (Glc), and distilled water, and attempted to use four different intelligent spectral variable selection algorithms [Competitive Adaptive Reweighted Sampling (CARS), Randomized Frog Hopping Algorithm (RF), Genetic Algorithm (GA), and Variable Projection Importance Algorithm (VIP)] to perform the Hb water interference-resistant feature band preferences, while combining partial least squares (PLS) in parallel to build a robust quantitative model of Hb. In addition, the applicability and validity of the model were validated using three prediction sets P1, P2, P3 with different water backgrounds (the formulation method and composition were kept the same, and only the water content increased sequentially). The results showed that RF, GA, and VIP could effectively screen out the characteristic wavelengths of Hb with low sensitivity to water changes and successfully correct the water effect, but due to the large number of characteristic variables they screened out and the existence of a large number of redundant and water interference variables, this ultimately made the model's robustness less than ideal. The CARS algorithm performed the best, and the RMSEP of the three prediction sets were 0.016, 0.017, and 0.038, which is closer to the RMSECV of the calibration set. Therefore, NIRS combined with the variable selection can reduce the effect of water on model robustness and improve the prediction accuracy of the model by the method of selecting effective wave number intervals, and CARS may be one of the ideal algorithms to solve such problems. [ABSTRACT FROM AUTHOR]

The fashion industry's reliance on dyes contributes significantly to environmental pollution, which disturbs the ecological balance. To address this issue, we used ZnO/Mg combined with activated carbon (AC) at various concentrations (0.1 g, 0.5 g, and 1 g), which were synthesized via sol–gel and mechanical alloying processes. The analysis of X-ray diffraction shows reduced crystallite size, with d-spacing change (→ d ← ) for ZnO/Mg/AC (0.5 g) and (← d → ) for ZnO/Mg/AC (1 g), respectively. The results of the IR spectrum indicated the main vibrations is MgO and Zn–O bonds at wave numbers 673 cm−1 and 467 cm−1. It was found that ZnO/Mg/AC (1 g) shows high degradation performance D % : 86.15% as a consequence of reduced crystallite size: 22.67 nm, decreased skin depth: 0.002 cm, widening of optical phonon vibration ( Δ (LO - TO) ): 252 cm−1 and increased E g : 4.6 eV as a function AC variation. Moreover, the finding of high photocatalytic performance ≥ 80% for 0.25 mL MB dissolved in 250 mL distilled water is obtained from all composites. Based on these results, ZnO/Mg/AC shows potential as a photocatalyst to solve the MB waste problem. [ABSTRACT FROM AUTHOR]