Wave Method Research Articles

Valence electron count-based density functional theory to investigate structural stability, optoelectronic and thermoelectric properties of half-Heusler ZrYAu (Y = B, Al) alloys.

The full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT) and semi-classical Boltzmann transport theory under the constant relaxation time approximation has been employed to investigate the structural, mechanical, optoelectronic and thermoelectric properties of novel half-Heusler (HH) ZrYAu alloys (where Y = B or Al) withvalence electron count (VEC) of 8. Our results indicate that both compounds are mechanically stable in structure Type 1 and possess negative formation energies. Additionally, ZrBAu and ZrAlAu display semiconducting behavior, with ZrBAu showing a direct band gap, 0.753 eV (0.774 eV) at point Γ→X and ZrAlAu exhibiting an indirect band gap, 0.431 eV (0.482 eV) at point Γ→Γ, using the generalized gradient approximation (GGA) and Modified Becke and Johnson-generalized gradient approximation (mBJ-GGA), respectively. Based on optical properties, both ZrBAu and ZrAlAu exhibit high optical conductivity within the visible spectrum. In terms of visible light absorption, ZrBAu primarily absorbs blue light, while ZrAlAu absorbs yellow, blue-green and violet light. However, both compounds are effective absorbers of UV light. Regarding thermoelectric performance, the thermoelectric parameters reveal that ZrBAu and ZrAlAu demonstrate significant p-type thermoelectric power. These half-Heusler alloys have a high-power factor, making them promising candidates for thermoelectric applications.

Prediction of thermoelectric properties for monolayer BiSbTeSe2

The full-potential linearized augmented plane wave method and the semi-classical Boltzmann theory are used to calculate the thermoelectric properties of monolayer BiSbTeSe2. For the monolayer BiSbTeSe2, the Tran-Blaha-modified Becke-Johnson (TB-mBJ) method calculates a larger band gap than that calculated by the generalized gradient approximation (GGA) method. Where the bandgap calculated by TB-mBJ is 0.94, while the bandgap calculated by GGA is 0.85. The absence of imaginary frequencies in the monolayer BiSbTeSe2 phonon band structure ensures its dynamic stability. The contribution of the optical branch to the lattice thermal conductivity is low due to the strong scattering of the optical branch. So the contribution to the lattice thermal conductivity mainly comes from the acoustic branch. The maximum frequency of the acoustic branch is 1.8. The monolayer BiSbTeSe2 has a low lattice thermal conductivity due to the low frequency of the acoustic branch. AIMD simulations confirm its thermal stability. Finally, the ZT value of monolayer BiSbTeSe2 is calculated using TB-mBJ to peak at about 0.98 at a carrier concentration of 2×1020 cm-3 and a temperature of 1125 K. The ZT value of monolayer BiSbTeSe2 is calculated using TB-mBJ.

Numerical Study on the Influence of Suction near Expansion Corner on Separation Bubble

Suction is an important control method in the shock wave and boundary layer interaction (SWBLI). Aimed at the problem of separation bubbles induced at the expansion corners, this study investigates the influence of suction on both the dimensions of bubble and the structure of the flow field at varying positions and back pressures under Ma = 2.73. As the upstream suction hole moves to the shoulder point, the size of the separation bubble decreases slightly. The decrease in back pressure leads to an increase in flow deflection angle αh. The low-kinetic-energy fluid in the boundary layer is removed and the thickness of the boundary layer decreases. Suction downstream of the shoulder point leads to an obvious change in separation bubble size. When the bleed position is upstream of the actual location of incident shock (Ddown = 2δ), the separation zone is located at the trailing edge of the hole, and the convergence of the separation shock wave (SS) and the barrier shock wave (BSW) leads to a large increase in the pressure plateau. At the downstream of the incident shock (Ddown = 5δ), the separation zone is situated at the leading edge of the hole, resulting in a substantial reduction in the size of the separation bubble. The flow reaches 88.5% of the theoretical expansion value at the shoulder point and directly turns into the bleeding area at the leeward side of the separation bubble. The deflection angle αh reaches the maximum of 46°, and the sonic flow coefficient Qsonic increases significantly. At the theoretical incident shock position (Ddown = 7δ), the separation zone is far from the suction hole position; the two are almost decoupled. The size of the bubble increases rapidly and the reattachment shock wave (RS) appears.

The exponential function coefficient characteristic of the fault voltage forward traveling wave and protection method for microgrid

Abstract Existing microgrid protection methods suffer from false action or non-action due to the difficulty of wave head extraction. The time-domain expressions of voltage forward traveling wave for internal faults or external faults in microgrid are derived in this paper, and the exponential function coefficient characteristic of the fault voltage forward traveling wave is obtained: the maximum value of exponential function coefficient for the internal fault is greater than that of the external fault. Based on this, a novel microgrid protection method is proposed, which uses the exponential function coefficient characteristic of the fault voltage forward traveling wave. The exponential coefficients are accurately extracted using the Levenberg–Marquardt algorithm, and the fault identification of internal and external faults is determined based on the maximum value of the exponential function coefficients. The time window of the proposed method is 1 ms, which is only 10% of the time window of existing common protection methods using steady state, the speed of protection is enhanced. The simulation test results show that the proposed method is feasible and reliable in various operating states, fault locations, and fault types.

A frequency-domain beamforming procedure for extracting Rayleigh wave attenuation coefficients and small-strain damping ratio from 2D ambient noise array measurements

The small-strain damping ratio plays a crucial role in assessing the response of soil deposits to earthquake-induced ground motions and general dynamic loading. The damping ratio can theoretically be inverted for after extracting frequency-dependent Rayleigh wave attenuation coefficients from wavefields collected during surface wave testing. However, determining reliable estimates of in situ attenuation coefficients is much more challenging than achieving robust phase velocity dispersion data, which are commonly measured using both active-source and ambient-wavefield surface wave methods. This article introduces a new methodology for estimating frequency-dependent attenuation coefficients through the analysis of ambient noise wavefield data recorded by two-dimensional (2D) arrays of surface seismic sensors for the subsequent evaluation of the small-strain damping ratio. The approach relies on the application of an attenuation-specific wavefield conversion and frequency-domain beamforming. Numerical simulations are employed to verify the proposed approach and inform best practices for its application. Finally, the practical efficacy of the proposed approach is showcased through its application to field data collected at a deep, soft soil site in Logan, Utah, USA, where phase velocity and attenuation coefficients are extracted from surface wave data and then simultaneously inverted to develop deep shear wave velocity and damping ratio profiles.

Sensor importance-based optimal seismic acquisition design for surface waves

Surface wave methods aim to monitor the shallow subsurface non-invasively. Traditional multichannel surface wave acquisitions adopt evenly spaced receivers for convenience and simplicity. However, seismic acquisitions are often performed with coarse sampling due to financial constraints and practical issues with physical access. Compressive sensing (CS) has been extensively studied for industrial-scale seismic explorations, predominantly utilizing random undersampling of tens of thousands of receivers. These undersampling methods do not answer the critical question of optimality when small-scale, shallow seismic surface wave acquisition only allows tens of receivers and a few source locations. We propose an optimal seismic acquisition design (OSAD) framework, where the importance of each receiver is evaluated in a constrained sparse inversion framework for more accurate data reconstruction. Instead of randomized sampling, OSAD exploits the physical information available in previously acquired or simulated synthetic data. The sparsity of the acquisition geometry and of the seismic data in a transform domain is explored by nested convex optimizations for alternating directions by solving each sub-problem to find a solution to an overarching minimization objective function. We apply the OSAD framework to synthetic and field datasets. We focus on deriving optimal receiver geometry for seismic acquisition with a single source. The derived geometry automatically honors wave physics where high- and low-frequency data are prevalent for near- and far-offsets, respectively. We explicitly demonstrate the optimality of the acquisition by comparing the data reconstruction error resulting from OSAD with two existing random undersampling methods adapted to surface wave acquisition.

Time-lapsed in situ monitoring of mechanical property in deep soil mixing with surface wave

Evaluating the mechanical properties of deep soil mixing (DSM) requires destructive borehole coring because they are mainly situated underground. Although the surface wave method offers potential for quality assurance, its complexity arises from multi-mode phenomena and the need to re-evaluate inversion results, often necessitating manual interpretation. This paper presents a data-driven surface wave framework to retrieve a field DSM profile Vs over time, incorporating a mode-free forward operator and the Monte Carlo tree search inversion. Validations using synthetic data affirmed the framework’s accuracy and efficiency in tracking subsurface shear wave velocity. In a real-world DSM site, the proposed method successfully captures the evolution of mechanical properties across two DSM layers over the curing period, aligning well with site investigations and borehole coring. This pioneering monitoring framework integrates geotechnical engineering with geophysics expertise, underscoring the value of non-destructive seismic methods for measuring subsurface property evolution.

Fast and scalable finite-element based approach for density functional theory calculations using projector augmented wave method

Fast and scalable finite-element based approach for density functional theory calculations using projector augmented wave method

The EFG Rosetta Stone: translating between DFT calculations and solid state NMR experiments.

We present a comprehensive study on the best practices for integrating first principles simulations in experimental quadrupolar solid-state nuclear magnetic resonance (SS-NMR), exploiting the synergies between theory and experiment for achieving the optimal interpretation of both. Most high performance materials (HPMs), such as battery electrodes, exhibit complex SS-NMR spectra due to dynamic effects or amorphous phases. NMR crystallography for such challenging materials requires reliable, accurate, efficient computational methods for calculating NMR observables from first principles for the transfer between theoretical material structure models and the interpretation of their experimental SS-NMR spectra. NMR-active nuclei within HPMs are routinely probed by their chemical shielding anisotropy (CSA). However, several nuclear isotopes of interest, e.g.7Li and 27Al, have a nuclear quadrupole and experience additional interactions with the surrounding electric field gradient (EFG). The quadrupolar interaction is a valuable source of information about atomistic structure, and in particular, local symmetry, complementing the CSA. As such, there is a range of different methods and codes to choose from for calculating EFGs, from all-electron to plane wave methods. We benchmark the accuracy of different simulation strategies for computing the EFG tensor of quadrupolar nuclei with plane wave density functional theory (DFT) and study the impact of the material structure as well as the details of the simulation strategy. Especially for small nuclei with few electrons, such as 7Li, we show that the choice of physical approximations and simulation parameters has a large effect on the transferability of the simulation results. To the best of our knowledge, we present the first comprehensive reference scale and literature survey for 7Li quadrupolar couplings. The results allow us to establish practical guidelines for developing the best simulation strategy for correlating DFT to experimental data extracting the maximum benefit and information from both, thereby advancing further research into HPMs.

A solution of the modified Tzitzeica-Dodd-Bullough equation

In this work, we solve a modified Tzitzeica-Dodd-Bullough (TDB) equation using the tanh and Ricatti and Jacobi solitary wave methods. We get several families of solutions.

Shear wave velocity profiling of Riyadh City, Saudi Arabia, utilizing the multi-channel analysis of surface waves method

Abstract Geotechnical site characterization is very important for construction purposes. This study has been conducted in Diriyah area northwest of Riyadh City, Saudi Arabia, using the Multichannel Analysis of Surface Waves (MASW) method for site characterization through shear wave velocity profiling to 30 m depth. Nineteen MASW lines were carried out in various directions and lengths through the area. The entire process was meticulously parameterized to extract shear wave velocity for subsurface characteristics. MASW results revealed four distinct velocity zones based on National Earthquake Hazard Reduction Program. Fill material was approximately half a meter thick and was classified as very dense soil. The second layer exhibited velocities ranging from 800 to 1,500 m/s, indicating weathered and highly fractured limestone. The third layer showed velocities varying from 1,500 to 1,800 m/s, representing slightly weathered limestone. The fourth layer displayed high velocities ranging from 1,800 to 3,600 m/s, indicating hard and compact limestone rocks. Geotechnical boreholes were drilled down to depths of 10–35 m. These boreholes exposed the geological model that consisted of fill material (silty sand with gravel), followed by highly to moderately weathered limestone with vugs and cracks, and finally, massive limestone rock. Analysis of shear wave velocities identified weak zones, particularly fractured and weathered limestone rocks extending to 12 m in depth. Sinkholes of circular, elongated, and/or conical shapes were observed within this depth range. Moreover, some sinkholes were detected at depths greater than 12 m in specific locations (sites 1, 6, 9, 11, and 17). These sinkholes agreed with the previous study. These results highlight the need for targeted ground improvement methods, such as grouting or underpinning, particularly for construction over weaker zones. Accurate site classification and effective risk management are crucial for addressing these geotechnical and seismic challenges.

Wave and Physical-Chemical Methods for Managing the Development of Oil Fields with Anomal Reserves

Wave and Physical-Chemical Methods for Managing the Development of Oil Fields with Anomal Reserves

Results of gravity modeling of the central part of the Korsun-Novomyrhorod pluton (Ukrainian Shield)

Three-dimensional gravity modeling of the Gorodishchen and Smilyan gabbro-anorthosite massifs, located in the central part of the Korsun’-Novomirgorod pluton (Ukrainian shield), was performed. A three-dimensional model of the upper crust of the research area was developed using maps of the anomalous gravity field of 1:200 000 scale, taking into account the results of detailed seismic studies by the methods of the RWM (reflected wave method) and CDP (common depth point). Differences in the structure of the intrusive complex of the anorthosite-rapakivi granite formation and the gneisses of the Ingulo-Ingulets series surrounding it were reflected in the seismic wave fields, which made it possible to determine the boundaries of the entire intrusive. For separating the basic rocks and rapakivi granites that differ in their density, three-dimensional gravity modeling was performed using computer technology of automated interpretation of geophysical data based on the trial and error method. For the geological objects parameterization, an approximation model is proposed, which is represented by a set of three-dimensional rod bodies. In the process of solving the inverse problem, various criteria for local optimization of gravitaty field sources were implemented. Three different functionalswere calculated during the iterative process. It is proved that the joint use of the functionals allows to reduce various types of noise in the observed gravity data. During the solving the inverse problem we found out that using of various types of functionals in the algorithms of trial and error methods is quite appropriate. Three-dimensional gravity modeling made it possible to identify and outline gabbro-anorthosite bodies in the upper part of the section with maximum thickness of up to 4—5 km, to clarify the shape and dimensions of the rapakivi granites, and to study the contacts of the intrusive complex with the gneisses surrounding it. The obtained model, which takes into account all the available information on density and geometric parameters of the anomaly forming objects, could be used to obtain additional reliable geological information about the structure of the Gorodishchensk and Smilyan gabbro-anorthosite massifs. The reliability of this algorithm for three-dimensional trial and error gravity method, using an approximation model in the form of a three-dimensional rods construction, allows us to recommend it for the study of similar gabbro-anorthosite massifs of the Ukrainian Shield, primarily the Korosten pluton.

Field Scale Soil Moisture Estimation with Ground Penetrating Radar and Sentinel 1 Data

This study examines the combined use of ground penetrating radar (GPR) and Sentinel-1 synthetic aperture radar (SAR) data for estimating soil moisture in a 25-decare field in Sivas, Türkiye. Soil moisture, vital for sustainable agriculture and ecosystem management, was assessed using in situ measurements, SAR backscatter analysis, and GPR-derived dielectric constants. A novel empirical model adapted from the classical soil moisture index (SSM) was developed for Sentinel-1, while GPR data were processed using the reflected wave method for estimating moisture at 0–10 cm depth. GPR demonstrated a stronger correlation within situ measurements (R2 = 74%) than Sentinel-1 (R2 = 32%), reflecting its ability to detect localized moisture variations. Sentinel-1 provided broader trends, revealing its utility for large-scale analysis. Combining these techniques overcame individual limitations, offering detailed spatial insights and actionable data for precision agriculture and water management. This integrated approach highlights the complementary strengths of GPR and SAR, enabling accurate soil moisture mapping in heterogeneous conditions. The findings emphasize the value of multi-technique methods for addressing challenges in sustainable resource management, improving irrigation strategies, and mitigating climate impacts.

Development Status and Application Research of Wireless Charging Technology

As the demand for convenience and flexibility in modern electronic devices and industrial systems continues to grow, wireless charging technology has become one of the key solutions to the limitations of traditional wired charging. This technology has demonstrated broad application prospects in various fields such as consumer electronics, industrial automation, and medical devices. This paper systematically reviews the latest developments in wireless charging technology, providing a detailed analysis of the fundamental principles, advantages and disadvantages, and application scenarios of different wireless charging methods, including electromagnetic induction, electric field coupling, magnetic resonance, and radio wave methods. To address the technical challenges encountered in long-distance wireless charging, the article explores optimized solutions such as metasurface designs and relay coils. The article also discusses the crucial roles of frequency modulation technology and clean energy harvesting in enhancing wireless power transmission efficiency. Furthermore, the article delves into the practical applications and development trends of wireless charging technology in areas like consumer electronics and industrial applications.

Computational characterization of structural, electronic, elastic and magnetic properties of double half-Heusler alloy Fe2MnCoGe2

Using the augmented plane wave method based on density functional theory and implemented in the WIEN2k code, we study the structural, elastic, electronic, and magnetic properties of FeCoGe, FeMnGe, and the parent half-Heusler (HH) alloys, as well as their derivative Fe2CoMnGe2 double half-Heusler (DHH) compounds. By analysing the stability of the HH structure in both the ferromagnetic and non-magnetic phases of FeCoGe and FeMnGe alloys, we determine that the latter phase of type II and type III FeCoGe and FeMnGe arrangements is the most stable. The Fe2CoMnGe2 DHH alloy, which is derived from the magnetic and structural ground states of FeCoGe and FeMnGe HH alloys, is found to be most stable in the type II arrangement. Among these materials, the FeMnGe HH alloy demonstrates greater resistance to reversible deformation by shear strain, indicated by its higher Young's modulus, while FeCoGe shows the best overall resistance to deformation. The electronic structures of FeCoGe, FeMnGe, and Fe2CoMnGe2 compounds reveal metallic behavior in the spin-up channel and semiconducting behavior in the spin-down channel. Their half-metallic gaps are 0.437 (0.181) eV, 0.543 (0.224) eV, and 0.353 (0.035) eV, respectively, with Fe2CoMnGe2 DHH retaining half-metallicity despite a lower band gap. The total magnetic moments for FeCoGe, FeMnGe, and Fe2CoMnGe2 are found to be 3, 1, and 4 μB, respectively. Given their half-metallic properties, these alloys show potential as candidates for spintronic applications.

First principle calculations of structural, electronic, and optical properties of XSnO3 (X: Ca, Mg, Sr) perovskite oxides

The perovskite oxides XSnO3have garnered significant attention due to their potential applications in various fields, including electronics, photonics, and renewable energy technologies. This study presents a comprehensive theoretical investigation of the structural, electronic, and optical properties of XSnO3(X: Ca, Mg, Sr) compounds with density functional theory based on the full potential linearized augmented plane wave method. Our analysis begins with thoroughly examining the structural stability and lattice parameters of XSnO3compounds, revealing their robust perovskite crystal structures. These compounds' lattice constants, total energy, bulk modulus, and cohesive energy were determined. Subsequently, we delve into the electronic properties of XSnO3, elucidating their electronic band structures, density of states, and charge densities. The studied compounds are indirect bandgap semiconductors having band gaps in the visible range. Furthermore, our investigation extends to the optical properties of XSnO3, encompassing absorption spectra, refractive indices, energy loss function, reflectivity, extinction coefficient, and dielectric functions across a wide range of wavelengths. Overall, the excellent optical properties of these compounds make them suitable for optoelectronic applications.

Effect of anchor shear deformation on the propagation rules of excitation stress waves

To address the shear deformation failure resulting from misalignment of rock strata in anchor support, a range of methods, including laboratory tests, numerical simulation, and others, are employed to study the deformation process of anchor rods under shear comprehensively. This approach permits an investigation of the deformation characteristics of the surrounding rock and anchoring agent under shear. Moreover, the propagation characteristics of the stress wave in the anchor rods under shear with varying degrees of deformation have been elucidated. A novel non-destructive testing method for assessing the degree of shear deformation in anchor rods is proposed based on the correlation between the energy evolution law of the stress wave and the degree of anchor deformation. Following experimental verification, it was determined that the average discrepancy between the detection outcomes of the stress wave method and the actual measurement results was minimal and consistent. The findings provide a theoretical foundation for the non-destructive testing of anchor rod shear deformation under on-site support conditions.

DFT study of structural, electronic, optical and elastic properties of lead-free Bi based perovskites X2NaBiCl6 (X= K and Rb) with pressure

The pressure dependent structural, electronic, optical and mechanical properties of Bi-based cubic halide double perovskites, X2NaBiCl6 (X = K and Rb) are explored by implementing full-potential linearized augmented plane wave (FP-LAPW) method. At zero pressure, K2NaBiCl6 and Rb2NaBiCl6 posses indirect band gaps of 3.746 and 3.735eV, respectively and the band gaps decrease with increasing pressure for both compounds. The elliptical shape of charge density contours under high pressure ensured a strong covalent bonding between K/Rb and Cl atoms along (110) plane. We explored the essential optical properties for both compounds with different pressures and found a red-shift with increase in pressure. Furthermore, all the values of mechanical parameters, viz. elastic constants and moduli, Vickers hardness, Debye and melting temperatures are enhanced with increasing pressure. Due to suitable band gaps and appropriate mechanical parameters, both perovskites are proved as promising candidates in thermoelectric power generation and high temperature devices.

Density functional theory investigation of the phase transition, elastic and thermal characteristics for AuMTe2(M = Ga, In) chalcopyrite compounds.

We explored the pressure-induced structural phase transitions and elastic properties of AuMTe2 (M = Ga, In) using the full-potential linearized augmented plane wave method within the framework of density functional theory, applying both generalized gradient and local density approximations. Thermodynamic properties were further assessed through the quasi-harmonic model. We determined the transition pressures for the phase shift from the chalcopyrite structure to the NaCl rock-salt phase in both AuGaTe2 and AuInTe2. Additionally, we calculated and analyzed mechanical properties, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy, ductility versus brittleness, and hardness for the polycrystalline forms of AuMTe2 (M = Ga, In). The study also examined how temperature and pressure affect the Debye temperature, heat capacities, thermal expansion, entropy, bulk modulus, Grüneisen parameter, and hardness, utilizing the quasi-harmonic Debye model.