Surface Boundary Research Articles

Impact Evaluation of an External Point Source to a Generalized Model of the Human Neck

A methodical approach for assessing the effects of an external point source to a non-spherical model of the human neck is presented in this paper. The neck model consists of multilayered spheres to represent the skin, fat, muscle tissues, thyroid, and esophagus. The novel geometry enables the formulation of dyadic Green’s functions to accurately calculate the electric fields, considering the suitable surface boundary conditions and the superposition principle. Numerical outcomes for a Hertz dipole (i.e., a wireless network antenna) at the frequency of 2.4 GHz certify the benefits of the technique and elaborately describe the responsiveness of the neck/thyroid to the selected source.

The diurnal cycle from observations and ERA5 in precipitation, clouds, boundary layer height, buoyancy, and surface fluxes

The diurnal cycle from observations and ERA5 in precipitation, clouds, boundary layer height, buoyancy, and surface fluxes

Influence of lower-tropospheric moisture on local soil moisture–precipitation feedback over the US Southern Great Plains

Abstract. ​​​​​​​Land–atmosphere coupling (LAC) has long been studied, focusing on land surface and atmospheric boundary layer processes. However, the influence of humidity in the lower troposphere (LT), especially that above the planetary boundary layer (PBL), on LAC remains largely unexplored. In this study, we use radiosonde observations from the US Southern Great Plains (SGP) site and an entrained parcel buoyancy model to investigate the impact of LT humidity on LAC there during the warm season (May–September). We quantify the effect of LT humidity on convective buoyancy by measuring the difference between the 2–4 km vertically integrated buoyancy with the influence of background LT humidity and that without it. Our results show that, under dry soil conditions, anomalously high LT humidity is necessary to produce the buoyancy profiles required for afternoon precipitation events (APEs). These APEs under dry soil moisture cannot be explained by commonly used local LAC indices such as the convective triggering potential and low-level humidity index (CTP / HILow), which do not account for the influence of the LT humidity. On the other hand, consideration of LT humidity is unnecessary to explain APEs under wet soil moisture conditions, suggesting that the boundary layer moisture alone could be sufficient to generate the required buoyancy profiles. These findings highlight the need to consider the impact of LT humidity, which is often decoupled from the humidity near the surface and is largely controlled by moisture transport, in understanding land–atmospheric feedbacks under dry soil conditions, especially during droughts or dry spells over the SGP.

3D modeling of the stratigraphic and structural architecture of the Crotone basin (southern Italy) using machine learning with Python

The 3D modeling and representation of geological data have experienced significant growth within last years, due to the use of new technologies derived from advancements in land representation methods. These technologies enable interactive, intuitive and clear geological visualizations. This paper shows how, by using the open-source Python software (operable with a simple internet browser) for machine learning (linear and KNN interpolations), together with Geographic Information Systems (GIS), it is possible to achieve interactive 3D visualizations of geological features in sedimentary basins. This study is performed in the onshore-offshore Crotone area (southern Italy) where a large amount of stratigraphic datasets are available from core perforation and seismic profiles due to the presence of a natural gas extraction field. Thanks to a database of 63 drilling lithologic records and 43 check points obtained from 9 interpreted seismic sections, several 3D HTML models were constructed defining three stratigraphic units (Pre-Messinian, Messinian, and Post-Messinian). An overlap of the Post-Messinian top surface and an erosional truncation of the Messinian top surface toward the N were observed, together with a rising of the Pre-Messinian top surface in the northwestern area. This stratigraphic architecture may indicate differential subsidence and/or uplifting due to syn-sedimentary fault kinematics in the whole studied area. The 3D models with the stratigraphic unit boundary surfaces obtained with KNN interpolation (showing stepped and abrupt edges) allowed the interpretation in terms of structural architecture and syn-sedimentary fault kinematics. Three main sets of faults were deduced: N–S; NNW-SSE, and ENE-WSW. A minorly represented E-W set was added to the main sets. These faults generated a horsts-grabens structure, and in many cases a determinate set of faults caused a progressive lowering or rising of some areas with an “en echelon” arrangement. According to previous works, these deduced sets of faults (most of them strike-slip faults) have a good agreement with the general structural architecture and defined faults in the area.

Competition for resources in an exclusion model with biased lane-changing mechanism.

The motivation for the proposed work is drawn from the attachment-detachment observed in biological and physical transport processes that entail finite resources. We investigate the influence of limited particle availability on particle dynamics within two parallel totally asymmetric simple exclusion lanes, with one lane incorporating only particle detachment and the other considering particle attachment. We establish a theoretical framework by employing vertical mean-field theory in conjunction with singular perturbation technique. The analytical findings are supported by numerical and stochastic validation using a finite-difference scheme and the Gillespie algorithm. By utilizing these approaches, we scrutinize various stationary properties, including particle densities, phase boundaries, and particle currents for both lanes. Our analysis reveals that the complexity of the phase diagram exhibits a nonmonotonic trend in the number of stationary phases as the particle count increases. Each phase diagram is constructed with respect to the intrinsic boundary parameters, illustrating both bulk and surface transitions occurring within the lanes. The interplay between finite resources and coupling mechanisms gives rise to two phases involving upward shock in one of the lanes, while two phases exhibit synchronized downward shock in both lanes. Finally, we delve into shock dynamics to comprehend critical phase transitions occurring in the system.

Artificial neural network approach to simulate the impact of concentration in optimizing heat transfer rate on water-based hybrid nanofluid under slip conditions: A regression analysis

The recent era of science depends upon the efficient performance of the heat transfer rate in several engineering applications for which the role of nanofluids have a greater impact. Therefore, the impact of particle concentration in optimizing heat transfer analysis of water-based hybrid nanofluid is conducted via an artificial neural network. The combined effect of oxide nanoparticles such as MgO and TiO2 in water performs their effective role with various factors involved in the flow phenomena. The magnetized hybrid nanofluid flow over an expanding surface filled with porous material shows its noble behavior on the flow properties. Further, it is not usual to omit the effectiveness of the dissipative heat impact. Therefore, the role of viscous, Joule, and Darcy dissipation is incorporated in the energy profile for which the profiles became coupled. The designed nonlinear model invokes suitable similarity rules that give rise to a system of nonlinear ordinary equations in non-dimensional form. Afterwards, the traditional numerical approach is beneficial to conduct the simulation of the flow profiles. The optimization of the heat transfer rate analysis is obtained by the implementation of an artificial neural network (ANN) for the response of Nusselt number using various factors. The regression analysis for the embedding data shows the effectiveness of the proposed approach in this discussion. The proposed study describes the important outcomes as; an increasing slip produces a thinning in the bounding surface thickness for the case of pure fluid comparing to the nanofluid and hybrid nanofluid. Further, the data set used for the hybrid nanofluid shows an efficient fitting than the case of nanofluid.

Learning Deformable Hypothesis Sampling for Accurate PatchMatch Multi-View Stereo

This paper introduces a learnable Deformable Hypothesis Sampler (DeformSampler) to address the challenging issue of noisy depth estimation in faithful PatchMatch multi-view stereo (MVS). We observe that the heuristic depth hypothesis sampling modes employed by PatchMatch MVS solvers are insensitive to (i) the piece-wise smooth distribution of depths across the object surface and (ii) the implicit multi-modal distribution of depth prediction probabilities along the ray direction on the surface points. Accordingly, we develop DeformSampler to learn distribution-sensitive sample spaces to (i) propagate depths consistent with the scene's geometry across the object surface and (ii) fit a Laplace Mixture model that approaches the point-wise probabilities distribution of the actual depths along the ray direction. We integrate DeformSampler into a learnable PatchMatch MVS system to enhance depth estimation in challenging areas, such as piece-wise discontinuous surface boundaries and weakly-textured regions. Experimental results on DTU and Tanks & Temples datasets demonstrate its superior performance and generalization capabilities compared to state-of-the-art competitors. Code is available at https://github.com/Geo-Tell/DS-PMNet.

Analytical and numerical modeling of nonlinear lamb wave interaction with a breathing crack with low-frequency modulation

To characterize fatigue crack, an analytical calculation and finite element (FE) simulation of Lamb wave propagating through the region of a breathing crack in a two-dimensional(2D) isotropic plate were studied. Contact surface boundary conditions between the two surfaces of the vertical crack were considered to study contact acoustic nonlinearity (CAN) from the breathing contact crack in conjunction with the modal decomposition method, Fourier transform, and variational principle-based algorithm. Reflection and transmission coefficients in the fundamental frequency and second harmonic frequency were calculated and analyzed quantitatively. Different ratios of incident wave amplitude to crack width were studied to calculate CAN results related to micro-crack width. In addition, a low-frequency (LF) vibration(10 Hz) excitation was introduced to perturb the free surface vertical crack to close, and an interrogating Lamb wave(1 MHz) was used to study crack-related CAN in different conditions for interpreting the modulation mechanism. The contact boundary conditions between two surfaces of vertical crack were set which were dynamically changed due to the low frequency modulation. The clapping effects when the crack closed due to the modulation of the contact boundary conditions between the crack surfaces were studied and analyzed to get the quantitative correlation between CAN and LF modulation. The results obtained from the analytical model were compared with those from the FE simulation, showing good consistency. Knowledge of these effects is essential to correctly gauge the severity of surface cracks in the plate, which can be spotlighted in its application to quantitative evaluation of micro fatigue cracks in structural health monitoring(SHM).

An elastoplastic model with egg-shaped yield surface for coastal soft clay

A novel elastoplastic constitutive model with an egg-shaped yield surface (ESE model) is proposed herein to elucidate the strength-deformation characteristics of marine soft clay. One of the key improvements offered by this model is its ability to address the singularity associated with plastic strain increments at yield surface corners—a limitation commonly encountered in traditional elastoplastic models. Additionally, the proposed model demonstrates flexibility, as it can transform into various forms under different conditions. Subsequently, to evaluate the efficacy of this egg-shaped elastoplastic model, numerical simulations are performed within the finite element software ABAQUS using an implicit integration algorithm through the user material subroutine interface (UMAT). The simulations encompass standard triaxial consolidation tests involving saturated soft clay sourced from the Itsukaichi marine clay as well as two types of saturated kaolin clays. The outcomes derived from these simulations by the ESE model are compared with both empirical data and numerical simulations originating from the widely employed Modified Cam-Clay (MCC) model. The simulations of the ESE model for three conventional triaxial tests on clay demonstrate superior concordance with experimental measurements in comparison to the MCC model. This underscores the efficacy of the proposed ESE model in predicting the strength and deformation characteristics manifested by coastal soft clays under undrained conditions. Finally, the predictions for deformation in an adjacent tunnel according to the ESE model closely align with experimental measurements and prior to the simulations conducted using the MCC model and advanced models such as the bounding surface model and the unified model, thereby affirming its practical utility in engineering applications.

Vibration-assisted vat photopolymerization for pixelated-aliasing-free surface fabrication

Mask image projection-based vat photopolymerization (MIP-VPP) offers advantages like low cost, high resolution, and a wide material range, making it popular in industry and education. Recently, MIP-VPP employing liquid crystal displays (LCDs) has gained traction, increasingly replacing digital micromirror devices, particularly among hobbyists and in educational settings, and is now beginning to be used in industrial environments. However, LCD-based MIP-VPP suffers from pronounced pixelated aliasing arising from LCD’s discrete image pixels and its direct-contact configuration in MIP-VPP machines, leading to rough surfaces on the 3D-printed parts. Here, we propose a vibration-assisted MIP-VPP method that utilizes a microscale vibration to uniformize the light intensity distribution of the LCD-based mask image on VPP’s building platform. By maintaining the same fabrication speed, our technique generates a smoother, non-pixelated mask image, reducing the roughness on flat surfaces and boundary segments of 3D-printed parts. Through light intensity modeling and simulation, we derived an optimal vibration pattern for LCD mask images, subsequently validated by experiments. We assessed the surface texture, boundary integrity, and dimensional accuracy of components produced using the vibration-assisted approach. The notably smoother surfaces and improved boundary roughness enhance the printing quality of MIP-VPP, enabling its promising applications in sectors like the production of 3D-printed optical devices and others.

Pyrrolidinium Derivative‐Based Ionic Liquid Achieves Defect Passivation for Efficient Perovskite Solar Cells Exceeding 23%

In the rapidly developing field of photovoltaics, organic–inorganic metal halide perovskites are outstanding for their exceptional power conversion efficiencies (PCE), exceeding 26%. However, the full potential of these materials is often undermined by the prevalence of defects within their structure and at the grain surfaces, leading to significant nonradiative recombination losses. To meet this critical challenge, this study introduces a novel strategy involving a pyrrolidinium derivative and tetrafluoroborate ionic liquid, specifically 2‐pyrrolidin‐1‐ium‐1‐ethylammonium tetrafluoroborate (PyE(BF4)2), as an additive in the perovskite precursor. This approach aims to meticulously control crystallization processes and effectively passivate defects on the surface and grain boundaries of the perovskite. The formation of N─H…I− hydrogen bonds and strong ionic interactions, PyE(BF4)2 not only stabilizes the [PbI6]4− framework but also optimizes the valence band alignment with the hole transport layer. Empirical results demonstrate that perovskite solar cells modified with PyE(BF4)2 have achieved a notable PCE of 23.80% and remarkable stability exceeding 1300 h under standard testing protocols (ISOS‐V‐1). The findings emphasize the transformative potential of multifunctional ionic liquids in enhancing the performance and durability of perovskite‐based photovoltaic devices, marking a significant step forward in pursuing sustainable and efficient solar energy solutions.

Scattering of plane waves from stress-free boundary surface of a microstretch elastic solid half-space containing voids

Abstract Scattering phenomena of plane coupled waves from stress-free boundary surface of a microstretch elastic solid half-space containing uniform distribution of voids have been investigated. Using appropriate boundary conditions and Snell's law, the reflection coefficients corresponding to various reflected \textcolor{red}{sets of coupled} waves and their corresponding energy ratios have been presented. One of the boundary conditions leads to the vanishing of a cross-coupling parameter between curvature tensor and voids. Numerical computations have been carried out for a specific model and the variation of all the reflection coefficients and \textcolor{red}{their} corresponding energy ratios is depicted graphically against the angle of incidence. Some special cases have been reduced from the present model and discussed.

Streamlining FE and BIM Modeling for Historic Buildings with Point Cloud Transformation

ABSTRACT In this paper, a convenient workflow to obtain a simplified lightweight IFC description of a dense point cloud describing a historic building is proposed. The proposed procedure relies on slicing of the point cloud that aims at reconstructing the geometry of the solid. The resulting slices can then be easily employed in the generation of finite element (FE) and architectural building information modeling (BIM) models. In particular, the FE model generation procedure guarantees the obtainment of a conforming solid FE mesh ready to be used for structural purposes. Contextually, the architectural BIM model generation is achieved by slices extrusion to obtain the overall volume of the building. Then, the assembly of independent slice-based meshes is subjected to re-topology to obtain the overall watertight bounding surface of the building. A real historic structure is here used to show the effectiveness of the FE and BIM model generation procedures. Finally, the BIM model generation of an actual historic structure is carried out through the proposed workflow.

Thermoelastic diffusion in nonlocal orthotropic medium with porosity

The present article investigates the linear theory of nonlocal thermoelasticity in homogeneous orthotropic porous medium with diffusion in the context of dual-phase-lag model. The focal point of the present study involves an examination of Fick’s mass diffusion law and the generalized Fourier’s law within the context of the dual-phase-lag model of hyperbolic thermoelasticity. The incorporation of voids, mass diffusion with phase lagging in the diffusion flux is the basis for establishing the void diffusion-elasticity models. Furthermore, the new dual-phase-lag diffusion model introduces the consideration of nonlocal effects in mass transfer. The resolution of the problem involves the utilization of normal mode analysis, employed for solving, and encompasses the application of thermal shock at the surface boundary. Numerical calculations of stress components, displacement components, voids, temperature, and concentration of the diffusive material are performed for various distances and time intervals.

Temperature field simulation and optimization of processing parameters for laser-assisted machining of 3Y-TZP ceramics

To obtain low surface roughness in the laser-assisted machining of 3Y-TZP ceramics, a laser-assisted heating model of 3Y-TZP ceramics was established. The temperature field in the cutting zone was simulated using ABAQUS software to analyze the effects of laser power, rotational speed, and warm-up time on softening layer depth (distance between the workpiece surface and lower boundary of softening layer) and thickness (distance between the upper and lower boundaries of softening layer). Furthermore, the accuracy of the simulation results was verified through experiments. The Plackett-Burman design, Steepest ascent experiment, and Box-Behnken design method were used sequentially to optimize process parameters, and the surface quality, chip morphology, and tool wear of 3Y-TZP ceramic with laser-assisted cutting and traditional cutting were compared under the best process parameters. The results show that the rotational speed and laser power are the main factors influencing the softening layer depth and thickness, and the suitable warm-up time is 15 s; the most influential factor on the surface roughness is the cutting depth, and the optimized process parameter combinations for the best surface roughness are as follows: laser power of 90.3 W, rotational speed of 400 r/min, cutting depth of 0.21 mm, and feed speed of 4.4 mm/min; with laser-assisted, the surface roughness value of the workpiece is reduced by 54.12 %, the amount of tool wear is reduced by 56.5 %, the chip morphology is transformed from powder to strip with a length of more than 50 μm, and the primary material removal mode is changed from brittle removal to plastic removal.

A novel study of the Cross nanofluid with the effects of inclined magnetic field in fuzzy environment

The abstract is categorized into the following sections as.Background: There are various challenges in the real life, which are required to deal with the specific intervals. Fuzzification is most appropriate way to find the solutions and can provide the accurate results of uncertain problems in specific intervals. Some conditions and imprecise parameters make the problems based on the fluid flow uncertain.Purpose: This current attempt focuses on the investigation of inclined magnetized Cross fluid flow in fuzzy conditions embedded with the chemical process with fuzzy complex conditions.Formulation: The governing system of modeled PDEs are tackled numerically with the utilization of finite difference method under fuzzy conditions at the boundary surface.Finding: The magnetic parameter intensifies the velocity field and induced magnetic field H. Amplification in viscosity parameter diminishes the velocity.Novelty:α‐cut technique for the case of fuzzified Cross fluid has not been studied in the accessible literature.

Molecular Simulation of Competitive Adsorption of Hydrogen and Methane: Analysis of Hydrogen Storage Feasibility in Depleted Shale Gas Reservoirs

Summary As a clean energy carrier, hydrogen (H2) is considered an indispensable part of the energy transition roadmap. To meet increasing energy demand, extremely large storage capacities are required. Previous studies have focused on underground H2 storage in conventional depleted gas reservoirs, salt caverns, and saline aquifers. The increasing number of depleted shale gas reservoirs may be good candidates for H2 storage. In this work, we analyze the potential of H2 storage in depleted gas reservoirs using Monte Carlo (MC) simulations. The competitive adsorption of a methane-hydrogen (C1-H2) system under nanoscale conditions is investigated, including the effects of pore size, temperature, pressure, boundary material, and fluid composition. Our results show that C1 is preferentially adsorbed in a C1-H2 system. C1 forms the adsorption layer near the boundary surface, while H2 molecules are freely distributed in the pore. The fluid distribution indicates that H2 can be easily produced during H2 recovery processes, which contributes to H2 storage in depleted shale gas reservoirs. In addition, the effect of water on C1-H2 competitive adsorption is analyzed. The strong interactions between water and boundary atoms force C1 molecules away from the adsorbed region. This work provides a foundation for hydrogen storage in depleted shale gas reservoirs at a molecular level.

Sensitivity of boundary layer features to depth-dependent baroclinic pressure gradient and turbulent mixing in an ocean of finite depth

The present numerical study builds on Ekman (1905)’s work in surface boundary layer and extends the boundary value problem to overcome some of its limitations. Previous studies addressed model’s limitations by assuming that deviations from observations are usually ascribed to different eddy viscosity shapes, but seldom to the presence of baroclinic pressure gradients and shallow seas, which are the mainstays of this work. Improved solutions in the ocean boundary layer are obtained considering both depth-dependent wind-induced eddy viscosity and horizontal density gradients, ranging from well-mixed to highly-stratified conditions in a finite-depth ocean. High-order numerical solutions extend those in previous analytical and numerical works in the literature and widens the parameter space analyzed. Remarkably, the current profiles are obtained without ambiguity as a truly superposition of a geostrophic and a ageostrophic terms. Results indicate that, for a vertically-uniform eddy viscosity without density gradients and in shallow waters, currents are practically aligned with wind. As depth increases, misalignment between currents and wind increases and the complexity of the vertical structure increases. At large depths, Ekman’s values are attained, i.e., deflection angles relative to wind direction, θW, are θS−θW=−45∘ at the surface, where the current is maximum, and θT−θW=−90° for the depth-integrated transport (negative for deflections to the right in the Northern Hemisphere). These features remain regardless of the magnitude of the eddy-viscosity. For non-uniform eddy viscosity, θS−θW decreases from −45∘ up to −90∘ from low to high stratification level, respectively, whereas θT−θW is rather insensitive (θT−θW≈−90∘). Contrary to wind effects, the presence of the only vertically-uniform density gradient forcing, with constant eddy viscosity, deflects the surface angle θS−θD=+45∘ relative to the density-gradient direction, θD, in deep waters. Maximum currents no longer occur at the surface in this case. For non-uniform density-gradient profiles, current magnitude decreases overall while θS−θD≈+45∘ as long as the gradient affects the entire surface boundary layer. The deflection angle θT−θD∼+95∘ remains less sensitive to changes in density-gradient profile.

An alternative potential method for mixed steady‐state elastic oscillation problems

We consider an alternative approach to investigate three‐dimensional exterior mixed boundary value problems (BVPs) for the steady‐state oscillation equations of the elasticity theory for isotropic bodies. The unbounded domain occupied by an elastic body, , has a compact boundary surface , which is divided into two disjoint parts, the Dirichlet part and the Neumann part , where the displacement vector (the Dirichlet‐type condition) and the stress vector (the Neumann‐type condition) are prescribed, respectively. Our new approach is based on the classical potential method and has several essential advantages compared with the existing approaches. We look for a solution to the mixed BVP in the form of a linear combination of the single‐layer and double‐layer potentials with densities supported on the Dirichlet and Neumann parts of the boundary, respectively. This approach reduces the mixed BVP under consideration to a system of boundary integral equations, which contain neither extensions of the Dirichlet or Neumann data nor the Steklov–Poincaré‐type operator involving the inverse of a special boundary integral operator, which is not available explicitly for arbitrary boundary surface. Moreover, the right‐hand sides of the resulting boundary integral equations system are vector functions coinciding with the given Dirichlet and Neumann data of the problem in question. We show that the corresponding matrix integral operator is bounded and coercive in the appropriate ‐based Bessel potential spaces. Consequently, the operator is invertible, which implies unconditional unique solvability of the mixed BVP in the class of vector functions belonging to the Sobolev space and satisfying the Sommerfeld–Kupradze radiation conditions at infinity. We also show that the obtained matrix boundary integral operator is invertible in the ‐based Besov spaces and prove that under appropriate boundary data a solution to the mixed BVP possesses ‐Hölder continuity property in the closed domain with , where is an arbitrarily small number.

Thermal Boundary Layer over a Vertical Plate in Porous Medium with a Convective Surface Boundary Condition

Thermal Boundary Layer over a Vertical Plate in Porous Medium with a Convective Surface Boundary Condition