Interface Conditions Research Articles

Two-dimensional steady-state thermal analytical model of permanent magnet linear motor in Cartesian coordinates

Purpose Compared with the time-consuming numerical method and the complex lumped parameter thermal network method to solve the steady-state heat distribution of the permanent magnet (PM) linear motor, there is no analytical method based on the thermal partial differential equations. This paper aims to propose a two-dimensional (2-D) analytical model for predicting the steady-state temperature distribution of PM linear motors to improve the prediction accuracy and speed up the calculation. Design/methodology/approach Based on the complex Fourier series theory and Cauchy’s product theorem, this paper presents for the first time a general analytical solution for 2-D temperature field in Cartesian coordinates. Then, by combining the electromagnetic field finite element model (FEM), the copper loss, iron loss and PM eddy current loss are used as the heat sources of the thermal analytical model. Finally, the solution to the temperature field is obtained by solving the system equations under boundary and interface conditions. Findings The analytical results are in good agreement with those from the thermal FEM, and the calculation speed is significantly faster than that of the thermal FEM. Originality/value The multilayer model proposed in this paper can consider heat conduction, convection and radiation. It is not only suitable for PM linear motors but also has significant application value for the thermal analysis of electromagnetic devices modeled in 2-D Cartesian coordinates.

Thermodynamics of Surfactant-Enriched Binary-Fluid Systems.

Surface-active agents (surfactants) release potential energy as they migrate from one of two adjacent fluids onto their fluid-fluid interface, a process that profoundly impacts the system's energy and entropy householding. The continuum thermodynamics underlying such a surfactant-enriched binary-fluid system has not yet been explored comprehensively. In this article, we present a mathematical description of such a system, in terms of balance laws, equations of state, and permissible constitutive relations and interface conditions, that satisfies the first and second law of thermodynamics. The interface conditions and permissible constitutive relations are revealed through a Coleman-Noll analysis. We characterize the system's equilibrium by defining equilibrium equivalences and study an example system. With our work, we aim to provide a systematically derived framework that combines and links various elements of existing literature, and that can serve as a thermodynamically consistent foundation for the (numerical) modeling of full surfactant-enriched binary-fluid systems.

Node Adaptive Finite Element Method Based on Hodge Decomposition for 2D Maxwells Equation

The ecient numerical method of Maxwells equation needs to satisfy the interface condition of electromagnetic eld, so the nite element method of the electromagnetic eld problem generally uses the edge nite element space. Compared with the traditional nodal element, the disadvantage of the edge element is that it has many degrees of freedom and the condition number of the linear system is poor. In this paper, a method based on Hodge decomposition is used to convert Maxwells equation into a standard elliptic boundary value problem, then use node element to solve the ellipse problem and then get the numerical solution of Maxwells equation. Because Hodge decomposition is used, non-physical numerical solutions are avoided in numerical solutions. This paper uses Superior Capsular Reconstruction (SCR) and Polynomial Preserving Recovery (PPR) techniques to post-process the nite element numerical solution, which eectively improves the accuracy of the numerical solution, and establishes a reliable posterior error indicator and adaptive nite element method. Finally, four examples are given to verify the eectiveness and accuracy of the method.

Optimization of the Toroidal Magnetic Coil System for the Small Spherical Tokamak MEPhIST-0

A novel design of a continuous toroidal solenoid for the small spherical tokamak MEPhIST-0 is presented. The solenoid’s geometry is optimized in regard to stray magnetic fields perpendicular to the toroidal fields based on Maxwell’s equations and interface conditions for magnetic fields. The solutions obtained may in theory provide the level of stray fields ~10−10 of the toroidal fields. The design of the solenoid is tested by means of COMSOL modeling. The observed ratio of stray fields to the toroidal component of magnetic fields, Bp/BT is approximately ~0.4% at the plasma center. A ripple of the toroidal magnetic field at the edge of the plasma of δ ~ 0.8% is observed. The possibility of plasma breakdown with the chosen toroidal solenoid configuration was evaluated using the DINA calculation code.

Interpenetrating Composites: A Nomenclature Dilemma.

Interpenetrating phase composites are a novel class of heterogeneous structures that have recently gained attention. In these types of composites, one of the phases is topologically continuous and can maintain its structural integrity even if the other phase is removed. These composites are generally fabricated by casting, where the reinforcement penetrates into the precursor matrix as a continuous phase. However, the following dilemma arises: if the same two phases are combined by other powder metallurgical routes (due to differences in the fabrication and interfacial conditions), can they still be called interpenetrating phase composites? The reinforcement is added to the precursor matrix, as in any of the conventional composite processing methods. Most importantly, the reinforcement does not interpenetrate the matrix phase. The present Review discusses the various fabrication routes employed for the fabrication of these interpenetrating phase composites and attempts to identify the correct nomenclature for these composites fabricated via the powder metallurgical approach.

A finite element analysis to assess tibial bone fracture in malleolar regions following total ankle replacement: Influences of implant designs and implant-bone interfacial conditions.

Tibial bone fractures in the malleolar regions are a major concern during the early postoperative period of total ankle replacement (TAR), affecting patient outcomes such as stability and recovery. Design, placement, and anatomic misalignment of implant components can contribute to malleolar fractures. The aim of this study is to understand the influence of implant design features, including keel, peg, stem, and bar type design, and bone-implant interfacial conditions on malleolar fracture following TAR. Three-dimensional finite element (FE) models were generated for the intact and implanted tibia bone using computer tomography (CT) scan data. In the present study, both bonded (fully osseointegration) and debonded (non-osseointegration) implant-bone interface conditions were considered. The proximal part of the tibia was fixed. Finite element models of the intact and implanted tibia were solved for three distinct loading situations that correspond to three ankle positions throughout the gait cycle (GC). The influences of implant design and implant-bone interface conditions on malleolar fracture were examined by evaluating stress distribution in tibia bone post-implantation. Finite element (FE) analysis revealed that for the medial region, the tibia bone stress elevated to 10 MPa for the medial keel type design, indicating a possible fracture along the medial region. The risk of a medial malleolar fracture is highest for the medial keel type implant design compared to other designs. The bars, central keel, and stem type TAR implant designs also elevate stress on both the medial and lateral regions of the tibia bone. In the case of fully osseointegrated implant-bone interface conditions, the stress is slightly higher than in the case of non-osseointegrated implant-bone interfacial conditions. The study highlights the potential influence of specific implant designs on malleolar fracture. The current findings are crucial for designing new implants to mitigate tibial bone fracture risks and improve TAR outcomes.

On the nature of constructive boundary and interface conditions in stress-driven nonlocal integral model for nanobeams

On the nature of constructive boundary and interface conditions in stress-driven nonlocal integral model for nanobeams

Interfacial stress distribution analysis of natural fiberreinforced epoxy composites: a finite element approach

The strength of fiber-reinforced composites is greatly influenced by the bonding at the fiber-matrix interface. Experimental methods to study this interface are often challenging, making numerical approaches essential for evaluating the interfacial behavior in fiber-reinforced composites. This study investigates the stress and strain distribution in the fiber, matrix, and fibermatrix interface regions of natural fiber-reinforced single-fiber composites under tensile loading using the finite element method. Interface conditions were modeled using cohesive elements, with the composites represented in two dimensions through ABAQUS 6.14 software. The tie constrains contact model was employed to define binding interactions between the cohesive element, the fiber, and the matrix. The maximum stress value resulting from the simulation process is 202 MPa and a strain of 0.0449 mm. The stress is effectively distributed to the fiber, demonstrating that the cohesive element used in composite analysis under tensile loading serves as a reliable link between the fiber and the matrix. The simulation results revealed a maximum stress value of 202 MPa and a corresponding strain of 0.0449 mm. The stress distribution effectively transferred to the fiber, demonstrating the capability of cohesive elements to represent the interfacial bond in composites under tensile loading. These findings confirm that cohesive element modeling is reliable method for analyzing fibermatrix interactions in natural fiber reinforced composites, providing insights for optimizing composite performance.

Biocompatible Heterogeneous Packaging and Laser-Assisted Fluid Interface Control for In Situ Sensor in Organ-on-a-Chip.

The development of bionic organ-on-a-chip technology relies heavily on advancements in in situ sensors and biochip packaging. By integrating precise biological and fluid condition sensing with microfluidics and electronic components, long-term dynamic closed-loop culture systems can be achieved. This study aims to develop biocompatible heterogeneous packaging and laser surface modification techniques to enable the encapsulation of electronic components while minimizing their impact on fluid dynamics. Using a kidney-on-a-chip as a case study, a non-toxic packaging process and fluid interface control methods have been successfully developed. Experimentally, miniature pressure sensors and control circuit boards were encapsulated using parylene-C, a biocompatible material, to isolate biochemical fluids from electronic components. Ultraviolet laser processing was employed to fabricate structures on parylene-C. The results demonstrate that through precise control of processing parameters, the wettability of the material can be tuned freely within a contact angle range of 60° to 110°. Morphological observations and MTT assays confirmed that the material and the processing methods do not induce cytotoxicity. This technology will facilitate the packaging of various miniature electronic components and biochips in the future. Furthermore, laser processing enables rapid and precise control of interface conditions across different regions within the chip, demonstrating a high potential for customized mass production of biochips. The proposed innovations provide a solution for in situ sensing in organ-on-a-chip systems and advanced biochip packaging. We believe that the development of this technology is a critical step toward realizing the concept of "organ twin".

Development of a Caco-2-based intestinal mucosal model to study intestinal barrier properties and bacteria-mucus interactions.

The intestinal mucosal barrier is a dynamic system that allows nutrient uptake, stimulates healthy microbe-host interactions, and prevents invasion by pathogens. The mucosa consists of epithelial cells connected by cellular junctions that regulate the passage of nutrients covered by a mucus layer that plays an important role in host-microbiome interactions. Mimicking the intestinal mucosa for in vitro assays, particularly the generation of a mucus layer, has proven to be challenging. The intestinal cell-line Caco-2 is widely used in academic and industrial laboratories due to its capacity to polarize, form an apical brush border, and reproducibly grow into confluent cell layers in different culture systems. However, under normal culture conditions, Caco-2 cultures lack a mucus layer. Here, we demonstrate for the first time that Caco-2 cultures can form a robust mucus layer when cultured under air-liquid interface (ALI) conditions on Transwell inserts with addition of vasointestinal peptide (VIP) in the basolateral compartment. We demonstrate that unique gene clusters are regulated in response to ALI and VIP single stimuli, but the ALI-VIP combination treatment resulted in a significant upregulation of multiple mucin genes and proteins, including secreted MUC2 and transmembrane mucins MUC13 and MUC17. Expression of tight junction proteins was significantly altered in the ALI-VIP condition, leading to increased permeability to small molecules. Commensal Lactiplantibacillus plantarum bacteria closely associated with the Caco-2 mucus layer and differentially colonized the surface of the ALI cultures. Pathogenic Salmonella enterica were capable of invading beyond the mucus layer and brush border. In conclusion, Caco-2 ALI-VIP cultures provide an accessible and straightforward way to culture an in vitro intestinal mucosal model with improved biomimetic features. This novel in vitro intestinal model can facilitate studies into mucus and epithelial barrier functions and in-depth molecular characterization of pathogenic and commensal microbe-mucus interactions.

Rheology as a tool for identifying and characterizing optimal microemulsions formulations

AbstractThis study investigates the use of rheology to detect phase inversion in surfactant–oil–water (SOW) systems, offering a rapid method for identifying “optimal formulations.” Phase inversion through temperature or salinity variation provides a faster alternative compared with equilibrium scans. Using well‐defined polyethoxylated surfactants (C8EO3, C10EO4, C12EO5), phase inversion was monitored through viscosity measurements at a constant shear rate, with temperature as formulation variable. Emulsion viscosity reaches a minimum at the phase inversion point, which corresponds to an ultra‐low interfacial tension condition. A strong correlation between the reported fish‐tail temperature (T*) and the phase inversion temperature (PIT) was observed. While identifying optimal conditions through a formulation scan in a series of test tubes is relatively quick, evaluating the surfactant system's ability to reduce interfacial tension can take several weeks due to the requirement of equilibrium. Formulation conditions at which minimal emulsion viscosity occurs are related to those where three‐phase systems are obtained, with the magnitude of interfacial tension inversely proportional to this value. An empirical approach linking the emulsion destabilization zone with the interfacial tensions is proposed. By measuring this interval, it is possible to roughly predict interfacial tension for model systems.

Critical comparison of interfacial boundary conditions in modelling plasma–liquid interaction

Abstract Several computational models have been developed over the past decade with the goal to investigate the various processes that occur during plasma-liquid interaction. However, many different boundary conditions to describe transfer of chemical species over the gas-liquid interface have been reported in these investigations. In this work, we employ a computational model to test these various boundary conditions, and compare the results to experimental data for H2O2, O3, ·NO and HNO2, in order to assess how well these boundary conditions can describe the dissolution of different species. We show that the validity of the different formulas depends on the solubility of the investigated chemical species; they appear valid for species with high solubility (H2O2), but not for species with low (O3 and ·NO) or intermediate (HNO2) solubility. Finally, we propose an approach to reach better agreement, based on film theory in combination with the mass accommodation coefficient.

Analysis of imperfect interfaces in cobalt ferrite plates using a linear spring model: a comparative study with terfenol-D

PurposeThis research aims to explore the transmission of seismic surface waves through a two magneto-strictive materials i.e. cobalt ferrite and Terfenol-D when embedded in a plate-substrate configuration with non-ideal interface. The study focuses on understanding the impact of width of the plates, imperfect parameter, heterogeneity parameter on both the materials cobalt ferrite and Terfenol-D under magnetically open and short conditions.MethodologyTo achieve this, the study employs a variable-separable technique following Direct Sturm-Liouville method and appropriate boundary conditions to derive frequency relations for both magnetically open and short circuit scenarios. Numerical simulations are conducted to investigate the effects of width of the plates, imperfect parameter, heterogeneity parameter on both the materials cobalt ferrite and Terfenol-D under magnetically open and short conditions.FindingsThe research findings indicate that the phase velocity is increasing more in Terfenol-D as compared to Cobalt ferrite, either the case magnetically open or closed. Graphical comparisons highlight the impact of width plates, imperfect parameter, heterogeneity parameter on the characteristics on wave propagation clearly.Research limitationsThe study is confined to linear wave propagation and does not consider nonlinear effects. Additionally, the analysis is based on idealized material properties and interface conditions.Practical implicationsThe results of this research can contribute to the design and optimization of sensors, energy harvesters, and wave manipulation devices utilizing piezomagnetic materials. Understanding the behaviour of surface waves in these structures is crucial for their effective application.OriginalityThis study offers a comprehensive analysis of surface wave propagation in two different types of piezomagnetic composite structure by considering heterogeneity and interface conditions. The comparative study of different piezomagnetic models and the incorporation of heterogeneity and interface conditions contribute to the originality of the research.

Study on Interlayer Interface Deterioration of Double-Block Ballastless Track in Humid and Hot Environments Based on Acoustic Emission Technique

The deterioration of the interlayer interface of a double-block ballastless track is affected by the environmental temperature and moisture conditions, which will have a negative effect on its service life. Composite specimens with interlayer interfaces of double-block ballastless track were fabricated and deteriorated by an accelerated method, i.e., immersed in saturated ammonium chloride solution with various temperatures for different times. Then, the deterioration condition and mechanical properties of the composite specimens were investigated experimentally by a universal material testing machine and acoustic emission technique. The automatic sensor test (AST) method is capable of assessing the deterioration condition of the interlayer interface based on the relative wave velocity. The deterioration depth of the interlayer interface tends to increase with increasing solution temperature and immersion time. Both the solution temperature and immersion time have a negative impact on the splitting tensile strength and direct shear strength. A linear relation is found between the splitting tensile strength (direct shear strength) and the cumulative AE energy released at the fracture moment. The damage factor defined by the cumulative AE energy for most composite specimens is no greater than 0.2 before they are going to be fractured but increases sharply to 1.0 at the fracture moment.

Ferroelectric properties of HfAlOx-based ferroelectric memristor devices for neuromorphic applications: Influence of top electrode deposition method.

In this study, we compare the performance of ferroelectric memristor devices based on the fabrication method for the top electrode, focusing on atomic layer deposition (ALD) and physical vapor deposition techniques. We investigate the effects of these methods on the formation of the orthorhombic phase (o-phase) in HfAlOx (HAO) ferroelectric films, which is crucial for ferroelectric properties. The devices were fabricated with HAO films doped with 3.4% aluminum, followed by rapid thermal annealing at 700 °C. Our results demonstrate that the atomic layer deposition process forms a TiOxNy capping layer at the interface between the HAO film and the TiN top electrode, which promotes the o-phase formation. This capping layer effect leads to enhanced polarization characteristics, as evidenced by higher remnant polarization and tunneling electroresistance (TER) in the ALD-fabricated devices. The ALD method also results in a better interfacial layer condition, confirmed by a lower interfacial non-ferroelectric capacitance (Ci). Characterization techniques, including transmission electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. These structural advantages contribute to enhanced electrical performance, demonstrating neuromorphic applications. Here, our study highlights the significant impact of the ALD deposition method on enhancing the ferroelectric properties and overall performance of ferroelectric memristor devices, making it a promising approach for advanced memory and neuromorphic computing applications.

MASCS 1.0: synchronous atmospheric and oceanic data from a cross-shaped moored array in the northern South China Sea during 2014–2015

Abstract. This work presents a cross-shaped moored array dataset (MASCS 1.0) comprising five buoys and four moorings with synchronous atmospheric and oceanic data in the northern South China Sea during 2014–2015. The atmospheric data are observed by two meteorological instruments at the buoys. The oceanic data consist of sea surface waves measured using a wave recorder, temperature, and salinity from the surface to a depth of 400 m and at 10 and 50 m above the ocean bottom using conductivity, temperature, and depth recorders. They also include currents from the surface to a depth of 850 m measured using acoustic Doppler current profilers and measured at 10, 50, and 100 m above the floor using current meters. Additional measurements were taken for sea surface radiation, air visibility, chlorophyll, turbidity, and chromophoric dissolved organic matter at buoy 3 located at the center of the moored array. The data reveal air–sea interactions and oceanic processes in the upper and bottom ocean, especially the transition of the air–sea interface and ocean conditions from summer to winter monsoon and the effects of six tropical cyclones on the moored array. Multiscale processes were also recorded, such as air–sea fluxes, tides, internal waves, and low-frequency flows. The data are valuable and have many potential applications, including analyzing the phenomena and mechanisms of air–sea interactions and ocean dynamics and validating and improving numerical model simulations, data reanalysis, and assimilations. All the data described here are made publicly available at https://doi.org/10.5281/zenodo.14039870 (Zhang et al., 2024a).

Rheology-dependent surface wave characteristics in an advanced geomaterial flexoelectric plate with viscoelastic coating

Abstract This study investigates the transmission of seismic surface waves in a composite framework comprising a viscoelastic layer overlying a flexoelectric material. The study focuses on understanding the impact of different viscoelastic models (Maxwell, Newtonian, and Kelvin-Voigt) and interface conditions (smooth and welded contact) on the damping and dispersion characteristics of these waves. To achieve this, the study employs a variable-separable technique and appropriate boundary conditions to derive complex frequency relations for electrically open and short circuits scenarios. These relations are subsequently divided into real and imaginary parts to examine the dispersion and dampening properties, respectively. Numerical simulations are conducted to analyze the response of flexoelectric coefficient, viscoelastic layer thickness, and bonding parameter on phase velocity and dampening coefficient. The research findings indicate that the attenuation properties of the Maxwell and Newtonian models are lower compared to the Kelvin-Voigt model. Graphical comparisons highlight the influence of viscoelastic models and interface characteristics on wave propagation. This research can help in the development of sensors, energy harvesters, and wave manipulation devices that employ flexoelectric materials with viscoelastic coatings. Knowledge of surface wave dynamics in these structures is vital for their optimal performance.

Fluid Interaction Analysis for Rotor-Stator Contact in Response to Fluid Motion and Viscosity Effect

Fluid–structure interaction introduces critical failure modes due to varying stiffness and changing contact states in rotor-stator systems. This is further aggravated by stress fluctuations due to shaft impact with a fixed stator when the shaft rotates. In this paper, the investigation of imbalance and rotor-stator contact on a rotating shaft was carried out in viscous fluid. The shaft was modelled as a vertical elastic rotor system based on a vertically oriented elastic rotor operating in an incompressible medium. Implicit representation of the rotating system including the rotor-stator contact and the hydrodynamic resistance was formulated for the coupled system using the energy principle and the Navier–Stokes equations. Additionally, the monolithic approach included an implicit strategy of the rotor-stator fluid interaction interface conditions in the solution methodology. Advanced time-frequency methods, such as Hilbert transform, continuous wavelet transform, and estimated instantaneous frequency maps, were applied to extract the vibration features of the dynamic response of the faulted rotor. Time-varying stiffness due to friction is thought to be the main reason for the frequency fluctuation, as indicated by historical records of the vibration displacement, whirling orbit patterns of the centre shaft, and the amplitude–frequency curve. It has also been demonstrated that the augmented mass associated with the rotor and stator decreases the natural frequencies, while the amplitude signal remains relatively constant. This behaviour indicates a quasi-steady-state oscillatory condition, which minimises the energy fluctuations caused by viscous effects.

Measuring Relative Motion to Develop an Interface that Off-loads the Lower Limb

Abstract This investigation seeks to understand how the interfaces between fracture orthoses and the body affect the relative motion between the user and device. Excessive relative motion can inadvertantly load the fracture and prevent healing. Identifying interfaces that minimize relative motion will inform the designs of future fracture orthoses. Three types of interfaces were tested: a thigh corset, a sling that loaded the ischium, and a sling that loaded the patellar tendon. Eighteen able-bodied participants were fitted with an adjustable Interface Testing System (ITS) that redirected loads away from the foot and lower leg to more proximal parts of the body using different combinations of the three interfaces. A video motion capture system measured the relative motion between the ITS and the participants while varying the type of interface, load through the ITS, and tightness of the thigh corset. Average relative motion varied from 1.6-6.5 cm across all conditions. The thigh corset combined with either the ischial sling or patellar tendon-bearing sling allowed the least relative motion of the interface conditions tested. However, the combinations differ in the sagittal profile they create for the user as well as the breadth of injuries they can treat. All of these factors need to be considered in the design of future fracture orthoses.

Optimal local truncation error method on unfitted Cartesian meshes for solution of 3-D wave and heat equations for heterogeneous materials

In the paper we develop the optimal local truncation error method (OLTEM) with the non-diagonal and diagonal mass matrices on unfitted Cartesian meshes for the 3-D time-dependent wave and heat equations for heterogeneous materials with irregular interfaces. 27-point stencils that are similar to those for linear finite elements are used with OLTEM. There are no unknowns for OLTEM on interfaces between different materials; the structure of the global discrete equations is the same for homogeneous and heterogeneous materials. The calculation of the unknown stencil coefficients is based on the minimization of the local truncation error of the stencil equations, includes the use of the interface conditions and the entire PDE in derivations, and yields the optimal fourth order of accuracy of OLTEM with the non-diagonal mass matrix. This is two order higher than for linear finite elements with similar 27-point stencils. OLTEM with the diagonal mass matrix includes the rigorous calculation of the diagonal mass matrix and provides the optimal second order of accuracy. The 3-D numerical results for heterogeneous materials with irregular interfaces show that at the same number of degrees of freedom, OLTEM is even much more accurate than high-order (up to the 7-th order - the highest order in the commercial code COMSOL) finite elements with much wider stencils. Compared to linear finite elements with similar 27-point stencils, at an accuracy of 0.1% OLTEM decreases the number of degrees of freedom by 550–7300 times. This leads to a huge reduction in computation time.A new 3-D post-processing procedure has been developed with OLTEM for the calculation of the spatial derivatives of time-dependent numerical solutions. The spatial derivatives for each grid point are calculated with the help of one compact 27-point stencil (the same as that in basic computations). In contrast to known post-processing procedures, the new approach includes also the use of the time derivatives of the function, the interface conditions and the original PDE. The spatial derivatives of the OLTEM solutions calculated with the new post-processing procedure are much more accurate compared to those obtained by high-order (up to the 7-th order) finite elements with much wider stencils. At an accuracy of 0.1% for the spatial derivatives, OLTEM decreases the number of degrees of freedom by 1.9⋅106–6⋅109 times compared to linear finite elements. The new post-processing procedure can be equally applied to the calculation of the partial derivatives obtained by other numerical methods as well as to the numerical results for other PDEs.Due to the huge reduction in the computation time compared to existing methods and the use of trivial unfitted Cartesian meshes that are independent of irregular geometry, the proposed technique does not require remeshing for the shape change of irregular geometry and it will be effective for many design and optimization problems as well as for multiscale problems without the scale separation.