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Close attention was paid to contact effect between dam body and dam foundation of high earth rockfill dams. A soil–bedrock interface model is developed based on hyperbolic hardening rule of coarse-...

International audience; We introduce and study a diffuse interface model describing cell motility. We provide a detailed rigorous analysis of the model in dimension 1 and formally derive the sharp interface limit in any dimension. The model integrates the most important physical processes involved in cell motility, such as incompressibility, internal stresses exerted by the cytoskeleton seen as an active gel, and dynamic contact lines. The resulting nonlinear system couples a degenerate fourth order parabolic equation of Cahn-Hilliard type for the phase variable with a convection-reaction-diffusion equation for the active potential. The sharp interface limit leads to a Hele-Shaw type free boundary problem which includes the effects of surface tension and an additional destabilizing term at the free boundary. This additional term can be seen as a nonlinear Robin type boundary condition with the "wrong" sign. Such a boundary condition reflects the active nature of the cell, e.g., protrusion formation. We rigorously investigate the properties of this model in one dimension and prove the appearance of nontrivial traveling wave solutions for the limit problem when the key physical parameter exceeds a certain critical value. Although minimal, this new Hele-Shaw model, with Robin's unconventional boundary condition, is rich enough to describe the universal property of migrating cells that has been recently described by various theoretical biophysical models.

The prediction of the structural response of masonry structures under extreme loading conditions, including earthquakes, requires the use of advanced material descriptions to represent the nonlinear behaviour of masonry. In general, micro- and mesoscale approaches are very computationally demanding, thus at present they are used mainly for detailed analysis of small masonry components. Conversely macroscale models, where masonry is assumed as a homogeneous material, are more efficient and suitable for nonlinear analysis of realistic masonry structures. However, the calibration of the material parameters for such models, which is generally based on physical testing of entire masonry components, remains an open issue. In this paper, a multiscale approach is proposed, in which an accurate mesoscale model accounting for the specific masonry bond is utilised in virtual tests for the calibration of a more efficient macroscale representation assuming energy equivalence between the two scales. Since the calibration is performed offline at the beginning of the analysis, the method is computationally attractive compared to alternative homogenisation techniques. The proposed methodology is applied to a case study considering the results obtained in previous experimental tests on masonry components subjected to cyclic loading, and on a masonry building under pseudo-dynamic conditions representing earthquake loading. The results confirm the potential of the proposed approach and highlight some critical issues, such as the importance of selecting appropriate virtual tests for model calibration, which can significantly influence accuracy and robustness.

As an important method for connecting structural members, anchor bolts have been installed in many situations. Therefore, accurate evaluation of the pull-out strength of anchor bolts has always been an important issue, considering the complicated actual installation conditions and the problem of aging deterioration of the structural members. In general, the patterns of pull-out failure of anchor bolts can be classified into three types: adhesion failure, cone failure, and bolt break. However, it sometimes shows a mixed fracture pattern, and it is not always easy to predict the accurate pull-out strength. In this study, we attempted to evaluate the pull-out strength of anchor bolts under various installation conditions using SPH, which can analyze the crack growth process in the concrete. In particular, the anchor bolt-concrete interface model was introduced to SPH analysis in order to consider the bond failure, and it was confirmed that various failure patterns and the load capacity could be predicted by proposed SPH method. After that, the influence of several parameters, such as bond stress limit, anchor bolt diameter, and the anchor bolt embedment depth on the failure patterns and the load capacity, were investigated by numerical calculation. Furthermore, several useful suggestions on the pull-out strength of anchor bolts under improper installation conditions, such as the ends of members for the purpose of seismic retrofitting, are presented.

In a learning process to help students remember and understand the material, one effort can be made to provide essential points. Students are less interested in delivering essential points based on text because they are considered monotonous. Nowadays, many students tend to read comic books rather than books. Comics can wash away the emotions of readers in the storyline. Therefore, we need supporting media to help teachers visualize essential points in the book in comic form. So that to help teachers in this regard, a user interface model is needed. This research was conducted with a Goal-Directed Design approach to gain user perspective in developing supporting tools to visualize the material's crucial points in the form of comic strips. Testing the resulting model was carried out twice and each test involved 15 respondents to get maximum results. Based on the evaluation results using the USE Questionnaire evaluation method for the prototype made and the results were in the excellent category. Thus, the resulting user interface model supports teachers in delivering learning material in comic form following the expected objectives.

Reflectance, transmittance, and absorption of materials are also known as materials’ Fresnel problem. It is widely accepted that Interface model can be utilized to solve Fresnel problem of two dimensional materials. Here, we question the validity of Interface model. Theoretical and experimental results of two dimensional materials are analyzed, and theoretical optical response of two dimensional materials is derived based on thin film model. A new simple, approximate formula of 4πnkd/λ is proposed for calculation of absorption of two dimensional materials. It is found that, in essence, Interface model is a kind of approximate style of thin film model, the main difference between two models is term of (n2 − k2) at normal incidence. A significant error is introduced into reflectance calculation of two dimensional materials when Interface model is utilized. Thus, it is not correct to use Interface model to solve Fresnel problem of two dimensional materials. Thin film model rather than Interface model can be used to universally solve Fresnel problem of two dimensional materials, and exhibit a better agreement with experimental reflectance results than Interface model. Unexpectedly, on contrary to other remarkable, intriguing properties, two dimensional materials exhibit an ordinary Fresnel optical response, which is same with thin film.

Potential-dependent CO2 electroreduction pathways on Cu(111) are systematically studied with the aim of applying an improved electrode/aqueous interface model in this paper. The results indicate that our present defined CH2O and CHOH pathways may be able to parallelly take place at low overpotentials. Notably, the applied potentials will not alter the optimal CO2 reduction mechanisms. However, the presence of high overpotentials makes CO2 electroreduction more favorable, thus explaining why high overpotentials at experiments are required during CO2 electroreduction on Cu. Based on the potential-dependent energetics, the results suggest that COOH and CHO intermediates may be unstable at low overpotentials, in which COOH can easily change back to CO2 and CHO can easily change back to CO, thus preventing CO2 electroreduction. However, the high overpotentials will facilitate the formation and further electroreduction of CO and CHO. Thus, we can speculate that CO formation and then further electroreduction into CHO are the possible potential-limiting steps during CO2 electroreduction, which are regarded as the origin of experimentally observed high overpotentials. The present comprehensive understanding on CO2 electroreduction pathways can provide theoretical guidelines for efficiently designing Cu-based alloy electrocatalysts operated under the conditions of low overpotentials.

Orientation relationships {110}Nb||{100}γ and 〈111〉Nb||〈001〉γ between the crystal lattices of the Nb solid solution and particles of γ-silicide Nb5Si3 were determined by transmission electron microscopy. The following two types of matching planes were found: {110}Nb||{100}γ and {111}Nb||{001}γ. The former planes form steps at an angle of 120°. The correctness of the calculated orientation relationships was confirmed and these relationships were compared with experimental electron diffraction patterns using methods of mathematical modeling, which enable one to obtain superimposed electron diffraction patterns of several phases and tilt the model crystal. An interface model in two sections was constructed. The morphology of the interface between the particle and the matrix was explained in terms of structural features. The lattice misfit between the matrix and γ-silicide was calculated.

In this paper, we analyze finite element methods applied to pulsed electric model arising in biological tissue when a biological cell is exposed to an electric field. Considering the cell to be a c...

Z. Qiao’s work is partially supported by Hong Kong Research Council GRF grant No. 15325816. S. Sun and T. Zhang gratefully acknowledge that the research reported in this publication was supported by King Abdullah University of Science and Technology (KAUST) through the grant BAS/1/1351-01 and National Nature Science Foundation of China (No. 51874262).

Purpose The purpose of this paper is to develop a numerical model for the simulation of the dynamics of nanoparticles (NPs) at liquid–liquid interfaces. Two cases have been studied, NPs smaller than the interfacial thickness, and NPs greater than the interfacial thickness. Design/methodology/approach The model is based on the molecular dynamics (MD) simulation in addition to phase field (PF) method, through which the discrete model of particles motion is superimposed on the continuum model of fluids which is a new ide a in numerical modeling. The liquid–liquid interface is modeled using the diffuse interface model. Findings For NPs smaller than the interfacial thickness, the results obtained show that the concentration gradient of one fluid in the other gives rise to a hydrodynamic drag force that drives the NPs to agglomerate at the interface. Whereas, for spherical NPs greater than the interfacial thickness, the results show that such NPs oscillate at the interface which agrees with some experimental studies. Practical implications The results are important in the field of numerical modeling, especially that the model is general and can be used to study different systems. This will be of great interest in the field of studying the behavior of NPs inside fluids and near interfaces, which enters in many industrial applications. Originality/value The idea of superimposing the molecular dynamic method on the PF method is a new idea in numerical modeling.

The hydrodynamic limit of the Ginzburg–Landau ∇ ϕ interface model was derived in Funaki and Spohn (1997) and Nishikawa (2003) for strictly convex potentials. This paper deals with non-convex potentials under suitable assumptions on the free energy and identification of the extremal Gibbs measures which have been recently established at sufficiently high temperature in Cotar and Deuschel (2012). Because of the non-convexity, many difficulties arise, especially, on the identification of equilibrium states. We show the equivalence between the stationarity and the Gibbs property under quite general settings, and we complete the identification of equilibrium states. We also establish some uniform estimates for variances of extremal Gibbs measures.

We consider a model of a two phase flow proposed by Anderson et al. taking into account possible thermal fluctuations. The mathematical model consists of the compressible Navier–Stokes system coupled with the Cahn–Hilliard equation, where the latter is driven by a multiplicative temporal white noise accounting for thermal fluctuations. We show existence of dissipative martingale solutions satisfying the associated total energy balance.

Summary The majority of the models in the literature for the steam-assisted-gravity-drainage (SAGD) process solve the problem of conductive heat transfer ahead of a moving hot interface using a quasisteady-state assumption and extend the solution to the base of the steam chamber where the interface is not moving. This approach, as discussed by Butler (1985) and Reis (1992), results in inaccurate or sometimes infeasible estimations of the oil-production rate, steam/oil ratio (SOR), and steam-chamber shape. In this work, a new approach for the analytical treatment of SAGD is proposed in which the problem of heat transfer is directly solved for a stationary source of heat at the base of the steam chamber, where the oil production occurs. The distribution of heat along the interface is then estimated depending on the geometry of the steam chamber. This methodology is more representative of the heat-transfer characteristics of SAGD and resolves the challenges of those earlier models. In addition, it allows for the extension of the formulations to the early stages of the process when the side interfaces of the chamber are almost stationary, without loss of the solution continuity. The model requires the overall shape of the steam chamber as an input. It then estimates the movement of chamber interfaces using the movement of the uppermost interface point and by satisfying the global material-balance requirements. Oil-production rate and steam demand are estimated by Darcy's law and energy-balance calculations, respectively. The result is a model that is applicable to the entire lifetime of a typical SAGD project and provides more-representative estimations of in-situ heat distribution, bitumen-production rate, and SOR. With the improved knowledge obtained on the fundamentals of heat transfer in SAGD, the reason for the discrepancies between the various earlier models will be clarified. Results of the analytical models developed in this work show reasonable agreement with fine-scale numerical simulation, which indicates that the primary physics are properly captured. In the final section of the paper, the application of the developed models to two field case studies will be demonstrated.

For solid-fluid interaction, one of the phase-density equations in diffuse interface models is degenerated to a “0=0” equation when the volume fraction of a certain phase takes the value of zero or unity. This is because the conservative variables in phase-density equations include volume fractions. The degeneracy can be avoided by adding an artificial quantity of another material into the pure phase. However, nonphysical waves, such as shear waves in fluids, are introduced by the artificial treatment. In this paper, a transport diffuse interface model, which is able to treat zero/unity volume fractions, is presented for solid-fluid interaction. In the proposed model, a new formulation for phase densities is derived, which is unrelated to volume fractions. Consequently, the new model is able to handle zero/unity volume fractions, and nonphysical waves caused by artificial volume fractions are prevented. One-dimensional and two-dimensional numerical tests demonstrate that more accurate results can be obtained by the proposed model.

A dynamic magneto-viscoelastic interface model is proposed to study the effective magneto-mechanical responses of magnetorheological nanocomposites filled with carbon nanotubes. It is incorporated with the fundamental micromechanics principles, microstructural magnetic and mechanical coupling, and computational homogenization procedures. The field-dependent effective dynamic stiffness and damping of randomly dispersed, chain-structured nanocomposites are investigated with the consideration of imperfect interfacial conditions among nanofillers, micro-particles and the matrix. Comparisons are performed between the model prediction and experimental data for a specific type of Fe particle-reinforced elastomer nanocomposites filled with multi-walled carbon nanotubes to demonstrate the capability of the proposed model framework.

Mixed reality (MR) is an emerging technology which could potentially shape the future of our everyday lives by its unique approach to presenting information. Technology is changing rapidly and information can be presented on traditional computer screens following a WIMP (Windows, Icons, Menus, and Pointing) interface model, by using a head-mounted display to present virtual reality, or by MR which the process of presenting information through a combination of both virtual and physical elements. This paper classifies MR interfaces by applying a text mining method to a data base of 4296 relevant research papers published over the last two decades. The classification reveals the trends relating to each topic and the relations between them. This paper reviews the earlier studies and discusses the recent developments in each topic area and summarizes the advantages and disadvantages of the MR interface. Our objective is to assist researchers understand the trend for each topic and allows them to focus on the research challenges where technological advancements in the MR interface are most needed.

We consider the asymptotic limit of a diffuse interface model for tumor-growth when a parameter $\varepsilon$ proportional to the thickness of the diffuse interface goes to zero. An approximate solution which shows explicitly the behavior of the true solution for small $\varepsilon$ will be constructed by using matched expansion method. Based on the energy method, a spectral condition in particular, we establish a smallness estimate of the difference between the approximate solution and the true solution., 35 pages

The performance of film cooling is influenced by many parameters, and the nonuniform flow caused by the internal cooling system is found to largely affect the film cooling, which further complicates the in-hole flow and draws new difficulties in predicting the cooling performance. In this study, we find a very interesting phenomenon that there always exists an in-hole interface, on which distributions of many parameters, including the velocity and kinetic energy, are seldom affected by the mainstream. The existence of this specific interface can be observed for both cylindrical and shaped film cooling holes under most operating conditions. The theoretical analysis of this interface is conducted in this study based on the characteristic decomposition of the Navier–Stokes equation, and this interface is named as the characteristic interface. Theoretical analysis and numerical observations suggest the film cooling system can be simplified to two weakly coupled regions separated by this interface. It also explains why existing source term models for film cooling may fail. Based on these findings, a new prediction model is developed, which uses the convolutional neural networks (CNN) model to predict the boundary conditions on the characteristic interface. The new model outperforms existing source term models and yields similar accuracy as full-mesh computational fluid dynamics (CFD), while reducing the computational cost by one order of magnitude. This model is further evaluated in large eddy simulation (LES), showing moderate success. To sum up, the current work reports the characteristic interface phenomenon in the film cooling hole, based on which a new and efficient prediction model is developed and verified.

The purpose of this paper is clarifying the deform mechanism of CuTa/Cu and CuTa/Ta nanolaminates during nanoindentation test. Firstly, two kinds of amorphous and nanocrystalline interface model were built. Additionally, the Cu layer thickness in CuTa/Cu are λ between 3 A and 12 A. The Ta layer thickness in CuTa/Ta are μ between 3 A and 12 A. Secondly, nanoindentation test were introduced to get the elastic modulus and hardness of nanolaminates. As the results claimed that different deform mechanisms play the dominant role during the indentation load and unload. More exactly, when the Cu layer is less than 7 A the Cu layer dominate the deform mechanism, the elastic modulus and harness increase with increasing A. As A increasing much more, the CuTa layer will dominate the deform mechanism. In the contrast, the elastic modulus and hardness will decrease with increasing A. Similarly as CuTa/Cu model, CuTa/Ta model has an obviously change in the dominant role of deform mechanism. In the end, the influence of penetrate rate was discussed.

In this paper, the microscopic mechanisms of the transition metal oxides/RuO 2 memristor showing great performance in the recent advances were presented using ab initio theoretical methods. The calculations of oxygen vacancy formation, the Schottky barrier height, and the migration barriers for the HfO 2 /RuO 2 interface model suggest that there is mediated oxygen balance at the interface which contributes to the improvement of the device.

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