Search

Thin-walled tubular deployable composite boom (DCB) has gained significant attention due to its lightweight, simple structure and high packaging efficiency. The experimental and numerical simulation methods were employed in this paper to investigate the folding behavior of the DCB. Using T700/epoxy unidirectional reinforced prepreg as raw material, DCB specimens were prepared by the vacuum bag method. To complete the folding experiments of DCB specimens, a folding mechanism was designed and manufactured. Folding experiments of DCB specimens were conducted and folding moment versus rotational displacement curves were measured. In addition, a Finite Element Model (FEM) was established to predict the folding behavior of the DCB. Different failure criteria were considered in the numerical analysis, including the Tsai‐Hill criterion and maximum stress criterion. Prediction results using the FEM were compared with experimental results, and both sets of results were in good agreement. It is shown that the DCB can achieve the folding function without failure. The research results in this paper are of great significance to the practical engineering application of the DCB. [Display omitted] • Six tubular deployable composite boom specimens and a precise folding mechanism were designed and prepared. • Folding experiments were conducted to measure the folding moment and rotational displacement curves. • A finite element model for predicting the folding behavior of the tubular deployable composite boom was established. [ABSTRACT FROM AUTHOR]

The transport properties of gas diffusion layer (GDL) in proton exchange membrane fuel cell are important parameters in fuel cell modelling, and one method to measure them is to simulate the transport of each species at spatial resolutions of a few microns in a microstructure of the GDL. One issue in this method is the size of the microstructure as using an unnecessarily big sample could substantially increase the computational cost. Both carbon-paper and carbon-cloth GDLs are investigated and their microstructures are obtained using numerical generation and X-ray micro-tomography respectively at a resolution of 1.733 µm. For each reconstructed GDL, we use the orthorhombic lattice Boltzmann model to simulate fluid flow through some subsamples taken from it in both the in-plane and the through-plane directions; the results show that the permeability of all subsamples is anisotropic in that their permeability in the in-plane direction is higher than in the through-plane direction. For each GDL, we compare its permeability calculated using samples of different sizes and find its representative elementary volume (REV) – a volume above which the calculated permeability represents the average ability of the GDL to conduct fluids. [ABSTRACT FROM AUTHOR]

• The elastic instability phenomenon in hyperelastic layered materials with the phases exhibiting stiffening behavior is studied • A closed-form expression for the critical stretch of macroscopic instability is derived • An analytical prediction based on Bloch-Floquet analysis for the microscopic instability is exhibited • The critical parameters and transition of instability modes are found to be highly tunable with phase stiffening This paper investigates the elastic instability behavior in soft periodic laminates subjected to finite strains, with a focus on both macroscopic and microscopic instabilities. Considering the deformation-induced phase stiffening, the Gent model with a high bulk-to-shear modulus ratio describes the behavior of incompressible phases. This non-Gaussian statistics-based model captures the non-linear constitutive results from the limited extensibility of polymeric molecular chains. This paper derives an analytical prediction for the onset of macroscopic (or longwave) instability and microscopic instability as functions of material parameters. Moreover, a numerical Bloch-Floquet analysis is imposed on identifying the instability behavior under compression. We consider a wide range of phase combinations and find that the relatively rapid stiffening of the matrix compared to the stiff layer increases the stability of laminates by decreasing the critical stretch ratio. Essentially, properly manipulating the stiffening parameters can produce an absolutely stable region without observed instability. This paper also systematically illustrates the changes in instability and the transition between macro and micro instability in fully Gent laminates, which show higher stability than fully neo-Hookean laminates with larger critical stretch ratios. The critical characteristics of instabilities, such as critical stretch ratios and critical wavenumbers, can be controlled by the choice of stiffening parameters and other material properties, enlarging the tuning of soft laminates for desired buckling patterns in practical applications. [ABSTRACT FROM AUTHOR]

• A model to explore the multiphysics characteristic of semiconductors is presented. • The model determines the thermal and mechanical properties of complex patterns. • Results show a strong correlation between thermal and mechanical properties. • Dielectric bands asymmetrically affect thermal and mechanical behavior. • Machine learning can predict one property from another. As semiconductor performance improves through advanced package designs, it becomes important to consider both thermal and mechanical properties. Better understanding their relationship enhances system design and optimization. This study has introduced a numerical method that takes into account both thermal and mechanical fluxes to construct thermal and mechanical property maps for practical application in semiconductor engineering. Furthermore, this paper investigated the relationship between the two properties using the constructed property maps in commercially available semiconductor packages. Owing to the complexity of packaging design patterns, a coupled isoparametric mapping and machine learning (ML) method was introduced to investigate their effects. The model then determines and investigates the anisotropic equivalent thermal and mechanical properties of the commercialized semiconductor packages with complex pattern designs, according to the package materials, volume fractions of each material, and design patterns. This approach pursues more sophistication and practicality compared to simplified composite structure property evaluation models. Additionally, all processes in the algorithm are automated based on ML methods, making them practically applicable in the semiconductor industry. The study shows that there is a strong correlation between the thermal and mechanical characteristics in the complex package patterns. This relationship was able to form a fairly clear category based on the shape of the dielectric band because the dielectric band had significantly different effects on the thermal and mechanical fluxes. The study discussed the physical implications of the similarities and differences between the two behaviors and validated the results of the equivalent properties through finite element (FE) analysis. Finally, the study cross-validates the relationship by showing that information from one flux behavior can be used to predict the other based on the ML method. Based on the results, this paper can provide a better understanding of thermal and mechanical fluxes in semiconductor package patterns for package design and optimization. [ABSTRACT FROM AUTHOR]

Abstract A coupled numerical multi-physics model is developed to study the generation and variation mechanisms of friction torque, including fluid lubricating, micro-contact, sliding and heat transfer among the friction components. The engagement experiment is conducted to verify the accuracy of numerical model and investigate the stability of friction torque. The results show that the most significant operating factor affecting the friction stability is the applied pressure, followed by the rotating speed and the ATF temperature. Simultaneously, the operating factors have great influence on the torque response, engagement time and temperature rise. Moreover, the growth model of friction torque can be divided into two categories: one is increasing linearly and the other is concave parabolic rising. Highlights • A coupled numerical multi-physics model is presented to study the generation and variation mechanisms of friction torque. • The bench test is conducted to verify the accuracy of numerical model and investigate the stability of the friction torque. • The most significant operating factor affecting the friction stability is the applied pressure, followed by the rotating speed and ATF temperature. [ABSTRACT FROM AUTHOR]

A paper-based channel is a useful platform for the facile development of analytical devices implementing various chemical or biological reactions. To improve the analytical performance for various applications, it was necessary to analyze the detailed mixing characteristics within a paper-based channel. In this paper, we proposed a mathematical model to predict a concentration field created as a result of the imbibition of multiple fluids within a porous material. Interestingly, we found that the model exhibited a constant interdiffusion width within a paper-based channel even though the flow front velocity decreased over time. We were able to verify that our model accurately predicted the concentration field by comparing the experimental and numerical results for mixing in a 2 inlet-channel. Finally, we designed and fabricated paper-based channels to generate two (linear and non-linear) concentration gradients based on predictions made by the model. Both the experimental and numerical results were in good agreement, demonstrating that our model was accurate and useful for developing a paper-based analytical device utilizing the mixing characteristics of a sample and reagent flow system. [ABSTRACT FROM AUTHOR]

This study investigates roll paper fire using laboratory-scale experiments, with emphasis on water transport on burning surfaces for sprinkler suppression. Freeburn, water transport and suppression experiments were conducted using different types of paper with various basis weight and water absorptivity. For fire suppression, the experimental results showed different water transport patterns that are sensitive to the burning surface conditions. This is in contrast to the water transport under no fire conditions in straight vertical rivulets exhibiting highly non-uniform distribution along the roll perimeter. For roll paper fire growth, both surface delamination and exfoliation play a crucial role, with the delamination length increasing either linearly or exponentially with time and the exfoliation rates strongly dependent on paper basis weight. Although the effects observed at the small scale in this work may have differences from those at large scales, the experimental results yield insights for better understanding of fire growth and suppression mechanisms and provide extensive data for numerical model development and validation. [ABSTRACT FROM AUTHOR]

Abstract: Coating blades are used in the paper industry to meter off the excess coating applied to the paper. They are essential in attaining high-quality coating films with minimum operating cost. During the coating process, the blades are worn down at the tip and are replaced when the coating quality degrades. The objectives of this study are to predict the wear rate of the blades and examine the hypothesis that the blades wear into a quasi-steady-state wear profile, despite both low- and high-angle particle impact. Experimental data and results from finite element simulations are presented for a series of blade materials and suspensions. The approach taken differs considerably from earlier studies, in that it treats blade wear as erosion from the action of the impacting slurry particles rather than abrasion, thus explaining the enhanced wear around the heel. The current approach relies on computer experiments to solve the equations for the liquid flow field, the individual particle motion, the substrate deformation and the eroded volume of the blade, rather than employing empirical relations between wear rates and average fluid velocity. The shear thinning behavior of the coating suspension was properly taken into account. To validate the calculations, blade samples from both a pilot and an off-machine coater were collected at a variety of time intervals. The blade samples aided not only in the establishment of the wear rates and the identification of the wear patterns, but also in the confirmation of the steady-state wear hypothesis that is correctly predicted by the simulations. [Copyright &y& Elsevier]

Abstract: In this study, the determinability of time related colour changes in prints made using ink that dries on matte coated paper with the offset printing technique and infrared method, has been investigated with artifical neural networks after analysis of the experimental and numerical methods. In the experimental part a ECI 2002 CMYK test scale is printed on a 135g/m2 matte coated. The prints obtained were measured with a spectrophotometer at certain intervals and by converting the reflection data obtained into the CIELAB colour description spectrum, time related changes in printed colours have been determined. In the empirical study however, colour changes in prints made on matte coated paper using inks that dry with the infrared method are modelled numerically. The average deviation has been found to be 0.4%. As a result, artificial neural networks can be used with the aim to digitally calculate time related colour changes in the offset printing system. [Copyright &y& Elsevier]

This paper presents a comprehensive three-dimensional numerical investigation of horizontal square anchors embedded in geogrid-reinforced sand. Prior experimental studies have demonstrated notable enhancements in anchor uplift capacity when placed below geogrid reinforcement in soil. However, these results are limited to small anchor plates tested in laboratory conditions with over-reinforced sand. In contrast, this study focuses on large field-scale anchors and explores the influence of anchor width, embedment depth, reinforcement size, stiffness, and tensile strength on uplift capacity. The findings reveal that the optimal size for geogrid reinforcement is three times the anchor width. A diminishing improvement in uplift capacity with increasing anchor width was observed. Additionally, deeper anchor embedment reduces the uplift capacity improvement in geogrid-reinforced sand. The geogrid reinforcement is found to be more efficient in the case of shallow anchors placed in loose sand. The major contribution of this paper lies in the response analysis of large anchors and providing a better understanding of the uplift mechanism in geogrid-reinforced sand. • This paper presents a three-dimensional numerical investigation of large field-scale horizontal square anchors embedded in geogrid-reinforced sand. • The findings reveal that the optimal size for geogrid reinforcement is three times the anchor width (B) in contrary to the 5B value reported in the previous literature. • A diminishing improvement in uplift capacity with increasing anchor width was observed. • Deeper anchor embedment reduced the uplift capacity improvement in geogrid-reinforced sand. • The geogrid reinforcement is found to be more efficient in the case of shallow anchors. [ABSTRACT FROM AUTHOR]

This paper deals with stability of classical Runge–Kutta collocation methods. When such methods are embedded in linearly implicit methods as developed in [13] and used in [14] for the time integration of nonlinear evolution PDEs, the stability of these methods has to be adapted to this context. For this reason, we develop in this paper several notions of stability, that we analyze. We provide sufficient conditions that can be checked algorithmically using just the collocation points of the method to ensure that these stability notions are fulfilled by a given Runge–Kutta collocation method. We also introduce examples and counterexamples used in [14] to highlight the necessity of these stability conditions in this context. [ABSTRACT FROM AUTHOR]

Faced with the pressure brought by major changes in the shipping industry such as liner alliances and larger ships, more and more ports are inclined to choose cooperation. This paper first explains the reasons for the lack of spontaneous cooperation motives between ports through game theory and then points out that in order to achieve stable cooperation between ports, it may be necessary to use external forces to establish a cooperation mechanism that enables both parties to achieve a win-win situation. Further, the article explores the evolution path of port cooperation and the stability of cooperation through evolutionary game theory and finds that the incremental benefits of port cooperation, the cost of cooperation, the additional revenue of free-riding, the compensation for unilateral cooperation, and the distribution coefficient of incremental benefits are the key factors affecting the stability of port cooperation. Then, with the help of numerical simulation experiments, the influencing factors affecting the evolution path and stability of port cooperation are discussed. Finally, in order to promote port cooperation and improve the stability of cooperation, this paper puts forward corresponding policy implications and management insights for policymakers based on relevant influencing factors. • The article explains the reasons for the lack of spontaneous cooperation motives between ports through classical game theory. • to promote the cooperation among ports, the article analyzes the related determinants affecting the evolutionary paths port cooperation. • The article calculates the equilibrium points of the evolutionary game model, determines the corresponding equilibrium strategies. • Numerical simulation analysis was carried out on the changes of relevant parameters reflecting corresponding influencing factors. [ABSTRACT FROM AUTHOR]

This paper employs a numerical approach to investigate the impact of liquidity shocks on European options in modeling markets. To accurately capture the behavior of European options under liquidity shocks, a coupled system of differential equations is employed, consisting of a degenerate parabolic equation and a diffusion-free equation. The primary focus is on developing and analyzing implicit-explicit methods for numerically simulating European option pricing, specifically considering the presence of liquidity shocks while ensuring the positivity of the solution. The paper also includes convergence analysis and establishes the discrete comparison principle for the developed methods. Numerical experiments are conducted using both uniform and nonuniform meshes to validate the theoretical findings, demonstrating the efficiency and accuracy of the proposed methods. [ABSTRACT FROM AUTHOR]

This paper delves into the numerical analysis of the extended Fisher-Kolmogorov (EFK) equation within open bounded convex domains R ⊂ R d , where d ≤ 3. Two distinct finite element schemes are introduced, namely the semi-discrete and fully-discrete finite element approximations. The existence and uniqueness of solutions are established for both the semi-discrete and fully-discrete finite element approximations. Error bounds are investigated across different scenarios, including comparisons between the semi-discrete and exact solutions, as well as between the semi-discrete and fully-discrete solutions, along with the fully-discrete and exact solutions. An effective algorithm has been proposed to solve the nonlinear system resulting from the fully-discrete finite element approximation at each time step. The paper also provides computed numerical error results and showcases a variety of numerical experiments to further illustrate and support the findings. [ABSTRACT FROM AUTHOR]

A new shell element has been proposed for geometrically non-linear, finite element analyses of axially moving paper web. Web instability problems of paper travelling in a printing system, such as wrinkling and fluttering, pose special challenges in the numerical analyses. For examples, these are finite bending stiffness (as opposed to membrane), orthotropy, and non-uniform distributions of mechanical and hygro-properties (in different length scales). The new formulation has accounted for paper transport velocity and paper bending stiffness based on a mixed Lagrangian–Eulerian description of the motion. A natural coordinate system has been employed in the analytical and finite element formulations. Benchmarking with different finite elements in various tests showed that the proposed element is indeed more stable and reliable for the chosen application than existing elements. The usability of the shell element has been successfully demonstrated by two example problems: wrinkling of stretched isotropic and orthotropic membranes, and the vibration of a web showing a speed-tensioning effect above a critical web transport velocity. [Copyright &y& Elsevier]

The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic–plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent. [ABSTRACT FROM AUTHOR]

A numerical model based on the Fokker–Planck equation for studying the orientation of paper fibers in a suspension is presented. The model is implemented in a finite volume framework. The rotational operators are discretized on a triangulated half sphere and the spatial operators are discretized on a Cartesian octree grid, where internal walls are handled with immersed boundary methods. Transient solutions of the two dimensional fiber orientation distribution are computed in the entire fluid domain. This is in contrast to earlier approaches that either only compute along streamlines or one dimensional projected orientations. The fibers are assumed to have negligible inertia and thus to follow the fluid perfectly and to be evenly distributed. A head-box geometry relevant for paper forming is used to exemplify the usefulness of the method. The influence of translational and rotational diffusion is included in the presented method. [ABSTRACT FROM AUTHOR]

Abstract: The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. [Copyright &y& Elsevier]

Identifying the yarn end from the package surface is integral to the textile process. Using the automatic method based on negative pressure adsorption instead of the traditional manual method to capture the yarn end is an excellent solution to the time-consuming and inefficient problems caused by the latter. To clarify the influence of process parameters on the process of the yarn end being adsorbed to break away from the package surface by the suction nozzle, this paper first establishes a kinetic model of the yarn attached to the package surface. Next, the air-yarn interaction is solved using the momentum exchanged-based immersed boundary-lattice Boltzmann method (IB-LBM). Then, the effect of the distance between the suction nozzle and the package, the rotational speed of the package, and the airflow velocity in the suction nozzle duct on the movement of the yarn end with the airflow field are studied. Further, the regression model for the depth of the yarn end sucked into the suction nozzle duct when the package turns through a fixed angle is solved. Finally, with the goal of a high success rate, large distance, high efficiency, and energy saving, a multi-parameter optimization is performed using the Central Composite Design-based response surface methodology. The work has been proven effective through experimental validation and practical production applications. It provides a theoretical basis for the automatic process of yarn-end-capturing from the package in the textile field. • The kinetic model of the yarn end being adsorbed to break away from the package surface by airflow is established. • The air-yarn interaction is solved using the momentum exchanged-based immersed boundary-lattice Boltzmann method (IB-LBM). • The effects of several process parameters on the movement of the yarn end with the airflow field are studied emphatically. • Multi-parameter and multi-objective optimization are performed by the Central Composite Design-based response surface method. [ABSTRACT FROM AUTHOR]

The main aims of this paper are to investigate the existence and uniqueness results for the solution of an inverse source problem for a multidimensional, semilinear, backward parabolic equation, subject to Dirichlet boundary conditions, and to propose an iterative difference scheme for the numerical solution of the problem. The unique solvability of the difference scheme is established, as well. In the foundation of the theoretical results, some tools and facts from the operator theory, contraction principle and the Banach fixed-point theorem are applied. Furthermore, a comprehensive numerical analysis and several illuminating visualizations are carried out by employing the iterative difference schemes proposed on some test problems. [ABSTRACT FROM AUTHOR]

Highlights • The problem concerns slip flow of carbon–water nanofluid. • Three non-dimensional parameters are wrong. • Some profiles are truncated and wrong. [ABSTRACT FROM AUTHOR]

• Multiple evaluation methodologies used in retinal vessel segmentation identified. • Published scores in 100 papers categorized by the methodology they are based on. • The scores are numerically adjusted to eliminate the biases for comparability. • A new baseline ranking of segmentation techniques provided. • The comparison of incomparable scores is an ongoing phenomenon in the literature. [Display omitted] In the last 15 years, the segmentation of vessels in retinal images has become an intensively researched problem in medical imaging, with hundreds of algorithms published. One of the de facto benchmarking data sets of vessel segmentation techniques is the DRIVE data set. Since DRIVE contains a predefined split of training and test images, the published performance results of the various segmentation techniques should provide a reliable ranking of the algorithms. Including more than 100 papers in the study, we performed a detailed numerical analysis of the coherence of the published performance scores. We found inconsistencies in the reported scores related to the use of the field of view (FoV), which has a significant impact on the performance scores. We attempted to eliminate the biases using numerical techniques to provide a more realistic picture of the state of the art. Based on the results, we have formulated several findings, most notably: despite the well-defined test set of DRIVE, most rankings in published papers are based on non-comparable figures; in contrast to the near-perfect accuracy scores reported in the literature, the highest accuracy score achieved to date is 0.9582 in the FoV region, which is 1% higher than that of human annotators. The methods we have developed for identifying and eliminating the evaluation biases can be easily applied to other domains where similar problems may arise. [ABSTRACT FROM AUTHOR]

Abstract: A finite element procedure, developed in order to account for the effect of high anisotropy at folding of coated papers, is presented. The anisotropic behaviour (with very low stiffness in the thickness direction) is modelled using stiff structural elements (trusses and beams). The numerical results indicate that high elastic anisotropy leads to lower strain levels at folding than reported in previous analyses where this effect was not accounted for. High plastic anisotropy, on the other hand, will contradict this result. [Copyright &y& Elsevier]

Folding of coated paper is examined numerically using the finite element method. Particular emphasis is put on the behaviour of field variables relevant for cracking of the coating layers. In the numerical analysis, the basepaper is modelled as an anisotropic elastic–plastic material (both elastic and plastic anisotropy is accounted for) while the constitutive behaviour of the coating layers are approximated by classical (Mises) elastoplasticity. The numerical results suggest, among other things, that particular forms of plastic anisotropy can substantially reduce the maximum strain levels in the coating. It is also shown that delamination buckling, in the present circumstances, will have a very small influence on the strain levels in the coating layer subjected to high tensile loading. [Copyright &y& Elsevier]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

Continuous fibre reinforced ceramic matrix composites (CMCs) are increasingly being employed in safety critical applications. As a result, their use in these applications requires the adoption of appropriate design methodologies that are able to consider their complex non-linear mechanical behaviour. In this paper, a simple but robust formulation for continuum damage model, thermodynamically consistent and written under plane stress condition, is proposed for a laminated 2D woven composite material. This model is implemented via the Classical Laminate Theory (CLT) extended to non-linear behaviour to predict the behaviour of different stacking sequences. In-plane tensile tests were performed on an oxide/oxide composite up to 1000 °C to fully identify the model. The procedure is described and used on tests at room temperature before being extended higher temperature tests. Finally, the law and its coupling with the CLT are validated by means of tests on quasi-isotropic and cross-ply laminates at different temperatures. [ABSTRACT FROM AUTHOR]

In this paper, an improved projection scheme has been constructed for solving the nonstationary magnetohydrodynamic equations, based on the modular grad-div stabilization. Owing to the utilization of the projection scheme and some delicate implicit-explicit approach to the nonlinear coupled terms, the proposed scheme is linear, decoupled and unconditionally energy stable. In addition, the modular grad-div stabilization technique is introduced to improve the conservation of Gauss's law and mass, and reduce the splitting error of the projection method, which is simple to implement with a small intrusion step into existing code. In this way, the developed scheme can prevent the solver from breakdown and enhance computational efficiency with the increasing of grad-div parameters. What's more, we present a rigorous convergence analysis. Finally, several numerical experiments are performed to illustrate the theoretical consequences and their effectiveness. [ABSTRACT FROM AUTHOR]

Efficient finite difference/spectral approximation is proposed for the time-fractional diffusion equation with an inverse square potential on the unit ball in this paper. The efficiency of the method lies in the use of ball functions to mimic the singular behavior of solutions in space and L1 scheme on graded mesh to compensate for the initial weak singularity of solutions in time. The stability and convergence of the fully discrete scheme in both L 2 -norm and H 1 -norm are analyzed. Numerical examples are presented to illustrate the accuracy and efficiency of our proposed discrete scheme. [ABSTRACT FROM AUTHOR]

In this paper, a two-grid characteristic block-centered finite difference method is developed for solving a nonlinear Darcy-Forchheimer slightly compressible miscible displacement problem in porous media. The method is proposed for solving the nonlinear system in two steps. In the first step, the nonlinear equations are approximated on a coarse grid using the characteristic block-centered finite difference method. In the second step, the nonlinear system is linearized using Newton's method with a small positive parameter to ensure the differentiability of the nonlinear term | u | u in the Darcy-Forchheimer equation. The proposed two-grid method is rigorously analyzed, in which a priori error estimates of the velocity, pressure, concentration and its flux are provided, and the rates of convergence are O (ε + Δ t + H 3 + h 2). Finally, numerical experiments are conducted to demonstrate the effectiveness of the proposed methods by comparing the efficiency, especially in terms of CPU time. [ABSTRACT FROM AUTHOR]

This paper is devoted to a study of a history-dependent mixed hemivariational-variational inequality arising in contact mechanics. The contact problem concerns the deformation of a viscoelastic body with long memory, subject to a general friction law on one part of the boundary and a frictionless Signorini condition on another part of the boundary. The solution existence and uniqueness of the history-dependent mixed hemivariational-variational inequality based on a Lagrange multiplier approach are proved. Then, a fully discrete scheme is introduced and studied. The trapezoidal rule is used to approximate the integral in the history-dependent operator. For the spatial discretization, the linear finite elements are used to discretize the displacement field, and dual basis functions are used in the approximation of the Lagrange multiplier. Optimal order error estimates are derived for the displacement and the Lagrange multiplier under appropriate solution regularity assumptions. Numerical results are presented to illustrate the theoretical prediction of the convergence orders. [ABSTRACT FROM AUTHOR]

We consider a one-dimensional singularly perturbed 4th order problem with the additional feature of a shift term. An expansion into a smooth term, boundary layers and an inner layer yields a formal solution decomposition, and together with a stability result we have estimates for the subsequent numerical analysis. With classical layer adapted meshes we present a numerical method that achieves supercloseness and optimal convergence orders in the associated energy norm. We also consider coarser meshes in view of the weak layers. Some numerical examples conclude the paper and support the theory. [ABSTRACT FROM AUTHOR]

This article presents a novel approach using the Fibonacci wavelet collocation method (FWCM) for the numerical solution of Emden-Fowler-type equations. The Emden-Fowler equations are a class of nonlinear differential equations that arise in various fields of science and engineering, particularly in astrophysics and fluid dynamics. Due to their nonlinear and singular nature, the conventional approaches to solving these equations encounter difficulties. This method is particularly effective in handling problems with singularities, as it adapts naturally to the local behaviour of the solution. Here, we introduced the Fibonacci wavelet collocation method as a powerful numerical technique for tackling Emden-Fowler-type equations. The Fibonacci wavelet basis functions possess remarkable properties, including compact support, making them well-suited for approximating solutions to differential equations. The main advantage of this approach lies in its ability to reduce the computational complexity associated with solving Emden-Fowler equations, resulting in accurate and efficient solutions. Comparative analyses with other established numerical methods reveal its superior accuracy and convergence rate performance. Further, several examples demonstrate the method's flexibility when dealing with different singularity levels. This paper contributes to numerical analysis by introducing the Fibonacci wavelet method as a robust tool for solving Emden-Fowler-type equations. [ABSTRACT FROM AUTHOR]

In this paper, we first investigate the well-posedness and regularity of mild solution to a stochastic active fluids model driven by the additive noise. A fully-discrete scheme is proposed for solving the given model, which is based on the finite element method for spatial discretization and the backward Euler method for temporal discretization. By overcoming the difficulty of error analysis caused by the discrete Laplacian operator, we obtain the convergence results of the developed scheme. Finally, some numerical examples are provided to validate the theoretical results and we also simulate the motion states of the active fluids. [ABSTRACT FROM AUTHOR]

In this paper, we study a Cauchy problem of fractional diffusion equation concerning fractional Laplacian. We prove the existence and uniqueness of solution to the problem under investigation in Hölder space. Then we apply the Monte Carlo method to solving this Cauchy problem. For the problem with free force term, we derive an unbiased scheme which only produces the statistic error. For the problem with inhomogeneous force term, we establish the simple and high-order jump-adapted schemes by approximating the trajectory of symmetric stable process. The error estimates of these two jump-adapted schemes are given based on the Hölder regularity of the solution. Numerical experiments including even one hundred dimensional case confirm the theoretical analysis and show the numerical efficiency. [ABSTRACT FROM AUTHOR]

Focal point of this review is to provide a comparative display of qualitative and quantitative methodologies employed for the appraisal of interacting energy and climate policies, underlying their key features while presenting the most critical issues and limitations not addressed so far. Qualitative approaches provide a descriptive explanatory analysis of often non-quantifiable process in policy interactions, whereas modeling approaches provide numerical data estimating the extent of policy interaction impacts. Quantitative methods work best for narrowly specified policy combinations, while contextual implications and cause-impact effects are explained further via qualitative ones. In addition most evaluations so far adopt a rational view of policies and policy interactions leaving out a systemic evaluation of the institutionalism of interacting policies. Research analysis of energy and climate policy interactions is still young in comparison to the broad field of policy evaluation and impact assessment. However infants inherently tend to grow. Endeavors for a methodological framework that would allow for a systematic exchange of data between qualitative and quantitative approaches and would also include the relevance of the context as well as key casual relationships behind policy combinations, would provide the basis for further growth of knowledge in the field. [ABSTRACT FROM AUTHOR]

This paper proposes a performance degradation model based on empirical approaches, which can break down the power loss and quantify the influence of each aging phenomena from the overall performance degradation. With the presence of primary degradation mechanisms, the approach can be used to analyze the performance degradation of fuel cells under different degradation conditions. The aging parameters that represent hydrogen crossover, membrane resistance increase, and electrochemical active surface area (ECSA) loss are introduced to characterize the performance degradation. Based on the polarization behavior of proton exchange membrane fuel cells (PEMFCs), the variations of degradation stressors are determinated by fitting the aging parameters to the measuring polarization curves. The empirical approach is validated by a 150 h durability experiment and agrees well with all polarization curves. The results show that ECSA loss always maintains an apparent influence and hydrogen crossover accounts for 56% of the performance degradation in OCV. • An empirical approach is developed to analyze the durability of PEMFC. • The integrated effects of degradation stressors are considered. • Variations of degradation stressors during dynamic cycles are studied. • Voltage degradation due to various aging mechanisms is investigated. [ABSTRACT FROM AUTHOR]

In this paper, Er3+ doped TeO 2 -ZnF 2 -BaF 2 -KF-Ta 2 O 5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems. [ABSTRACT FROM AUTHOR]

This paper carried out a high-temperature thermal gradient cycling test of ceramic matrix composites (CMCs), investigating the failure characteristics of CMCs in non-uniform high-temperature environments. The result shows that the damage characteristics of CMCs under thermal gradient environments are significantly different from those under uniform temperature environments. The SiC fiber pull-out lengths at different yarn fractures have obvious differences in the thermal gradient direction. The thermal stress damage propagation pattern of CMCs under the thermal gradient environment is revealed by numerical analysis, and its residual mechanical properties under different thermal gradient environments are predicted. The numerical results could be adopted as a theoretical basis and suggestions for temperature control of CMCs components in practical applications. [ABSTRACT FROM AUTHOR]

In order to understand and master the diffusion mechanism and spatial concentration distribution of hydrogen leakage in the engine room, this paper studies the diffusion behavior and concentration distribution of hydrogen under the coupling effect of multiple factors, and further explores the optimal installation location of the sensors. The results indicate that when the ventilation rate increases by 1, 2, and 3 times, the diffusion volume of hydrogen decreases by about 0.4, 0.5, and 0.6 times. The harm of the increase in leakage diameter is greater than the leakage pressure. And the temperature has a greater impact on the hydrogen volume fraction in areas below 4 % and a smaller impact on areas above 4 %. In this environment, the sensors should be installed at or above 5.5 m in the rear of the engine room and above the axis of the hydrogen transport pipeline interface, valves and other places prone to leakage. • Taking a ship engine room as the research object. • The influence of various factors on hydrogen distribution is compared. • The spatial concentration distribution of hydrogen leakage is analyzed. • Explored the installation position of the sensors. [ABSTRACT FROM AUTHOR]

In this paper, we address a class of boundary layer originated singularly perturbed parabolic reaction-diffusion problems with Robin boundary conditions having large time delay; for the higher order numerical analysis. The boundary layer originated nonuniform mesh, is generated by adaptive moving mesh approach based on equidistribution principle. The mesh is obtained by solving a nonlinear system; involving the discrete problem and the discrete nonlinear mesh generating functions. We provide the theoretical mesh structure. The difference scheme for Robin type boundary conditions having normalized flux; uses a combination of space and time discretizations so that the order of convergence in space is higher than the usual linear accurate upwind discretization in space. The present theoretical convergence analysis requires less regularity of the solution and proves to be exactly second order parameter uniform accurate in space. Numerical experiments highly validate the theoretical findings and also show that the present approach is better than the well-known upwind discretizations. [ABSTRACT FROM AUTHOR]

The energy sector is actively transitioning towards climate-neutral solutions, emphasizing advancements in clean power generation technologies. Cogeneration systems based on solid oxide fuel cells (SOFC) currently exhibit higher electrical efficiencies than conventional plants, but their operation can still be improved. One of the approaches to increase its efficiency is implementing anodic off-gas recirculation. In this work, a numerical model of a 10 kW SOFC installation with anodic gas recirculation was analyzed using Aspen HYSYS software. System fueled with three alternative fuels (natural gas, hydrogen, and ammonia) was tested. In this paper it was proven that anode-off gas recirculation improves the electrical and total efficiency of the system for each fuel type. The cogeneration unit with a SOFC stack can operate safely over a wide range of recirculation ratios without need for additional modifications. Ammonia-fueled units achieve electrical efficiency (55%) higher than hydrogen-based system (47.6%) but lower than installation fueled with natural gas (61.8%). • Anode off-gas recirculation in combined heat and power based on SOFC was studied. • Three fuels where considered: nautral gas, hydrogen and ammonia. • Wide range of recirculation can be achieved for all three fuels without modification. • Optimal recirculation ratio was found for each fuel and stack fuel utilization factor. • Highest electrical efficiency of up to 61.8% is achieved for natural gas fueled system. [ABSTRACT FROM AUTHOR]

The present paper studies Love-type wave propagation in a fluid-saturated fractured poro-viscoelastic layer sandwich between a coated elastic layer and a non-homogeneous anisotropic Voigt-type viscoelastic half-space. The interfaces between the layers and the half-space are considered as sliding contacts with two different sliding parameters. An impulsive point source is located at a varying depth in the intermediate poro-viscoelastic layer in the form of the Dirac-delta function. The vertical non-homogeneity in the half-space is assumed to be a combination of linear and exponential functions that vary with depth in the medium. Using the Fourier transforms and Green's functions, the equations of motion, in the form of partial differential equations, are solved analytically. An appropriate boundary condition is used to accomplish this. The closed form of the complex dispersion equation has been obtained by assuming that the wavenumber is in the form of a complex quantity. The validity of our model has been examined using several specific cases and compared to the classical Love wave equation. Numerical and graphical analyses of dispersion and displacement were performed using MATLAB software. It has been found that a single porous medium has a higher Love-type phase velocity than a double porous medium. Additionally, the sliding parameters increase the range of wavenumber when there is no phase velocity. An inverse relationship was found between the depth of the point source and the particle displacement in the coated layer. In addition to contributing to our understanding of geophysical phenomena and subsurface explosions, these findings may provide insight into the inner structure of the planet. • Layered media with sliding contacts are introduced. • The coupled Green's function approach is used for Love-type dispersion. • Wavenumbers for non-existence of phase velocity increase with sliding parameters. • An inverse relationship is found between the depth of the point source and the particle displacement in the coated layer. [ABSTRACT FROM AUTHOR]

This paper presents globally numerical properties of a new numerical scheme for a reaction-diffusion advection susceptible-infected-susceptible (SIS) model. A new numerical treatment technique is introduced in spatial discretization of advection-diffusion equation, which enables the numerical solutions to preserve the stability and positivity with less stepsize restrictions. The convergence, biological significance and globally stability of numerical solutions is explored in the paper. A threshold value, named by numerical basic reproduction number and denoted by R 0 Δ x , is introduced in the numerical stability analysis of the model. It is proved the numerical disease free equilibrium (DFE) is globally asymptotically stable if R 0 Δ x < 1 and unstable if R 0 Δ x > 1. It is shown the numerical basic number R 0 Δ x replicates the asymptotic behaviors of the basic reproduction number R 0 for the model. Some numerical experiments are given in the end to confirm the conclusions. [ABSTRACT FROM AUTHOR]

Abstract: Strains, computed by the finite element method, are evaluated and compared to an experimentally determined strain field. The analyzed low-density paper has been designed to ensure bond–breakage as the dominating damage mechanism and the paper material is approximately in-plane isotropic. An optical non-contact displacement measuring system has been used in fracture tests to determine the strain field in the crack-tip region of a pre-fabricated crack. Additionally, acoustic emission monitored tensile tests have been conducted to determine onset and evolution of damage processes and thereby enabling calibration of required constitutive parameters. The results suggest that the investigated paper material can tolerate significantly higher strains than what is predicted by a classic elastic–plastic J 2-flow theory. Immediately before onset of the final fracture (i.e., localization), the experimental measured normal strain in the near-tip region is around 60% higher than the computed strain when using exclusively an elastic–plastic theory for the corresponding load while the strain computed utilizing a non-local damage theory is of the same order of magnitude as the experimentally measured strain. Hence, it seems essential to include a non-local continuum theory to describe strains in the near-tip region quantitatively correct for paper materials. It is demonstrated that path independence of the well-known J-integral does not prevail for this class of material models. Only for the special situation of a homogenous damage field in the crack-tip region may the stress and strain fields be described by the well-known HRR-solutions. [Copyright &y& Elsevier]

Abstract: The paper presents and comments on the main experimental and numerical techniques in the considered paper. Several inaccuracies and problems in methodology are described, for example, description of the failure time and description of the dynamic tensile strength of glass (critical curve). The process of wave propagation reflection and interaction together with geometrical dispersion in bars is shown to present some disadvantages in analysis. [Copyright &y& Elsevier]

Abstract: The high fidelity generalized method of cells (HFGMC) has been originally developed by as a micromechanical method for periodic multi-phase composite media. A computational implementation of the HFGMC equations has been proposed by to enhance numerical efficiency, still with direct reference to the HFGMC formulation. Later, the same computational implementation is recast as a new method called “finite volume direct averaging micromechanics” (FVDAM), starting by . The current discussion paper has two aims. The first is to show that the FVDAM is not a new method and that it has the same assumptions and identical governing equations as those originally derived by the HFGMC. The only difference is in the solution procedure where intermediate dependent variables, in the form of average displacements at the interfaces, are used instead of directly solving for the unknown micro-variables; the coefficients of the displacement polynomials. Thus, renaming the HFGMC micromodel to FVDAM has not been justified. In fact, () have shown that the same reduction of variables can be achieved by a simple static condensation carried out at the global system of equations instead of introducing intermediate variables. The second aim of this paper is to address misrepresentations in a recent discussion paper by the FVDAM authors claiming, in part, that the HFGMC method using parametric geometry of the subcells should follow their formulation (termed parametric FVDAM). We show that the latter is limited to an incomplete quadratic expansion of the displacement and an approximation in the form of a priori constant Jacobian of the parametric mapping. However, the HFGMC with arbitrary cell geometry, (), has been formulated in a direct and general manner, i.e. retaining the full quadratic expansion of the displacement together with the complete Jacobian. Thus, the parametric FVDAM is a special case of the parametric HFGMC, i.e. when the Jacobian is sampled and evaluated only at one point, namely the origin of the parametric coordinate system. The intended new contribution of to refined micromechanics and progressive damage has been completely ignored by the FVDAM-discussion paper. Therefore, in order to maintain scientific clarity, it is strongly advocated to preserve the original name of the HFGMC method, regardless of the different computational implementations used for solving the governing equations for both orthogonal and parametric geometries of the subcells. [Copyright &y& Elsevier]

Abstract: We present a model for the laminated composite plate problem based on the Reissner–Mindlin model and first-order lamination theory. The weak problem based on this model is solved with the finite element method using stabilized MITC (mixed interpolation of tensorial components) finite elements. Detailed a priori estimates are given for the mixed finite element formulation of the problem. Explicit bounds for the continuity and coercivity constants of the coupling terms are presented, thus refining earlier results. Furthermore, we present an application of the theory to the paper cockling problem and investigate the effect of boundary conditions on the small-scale deformation of the solution numerically. [Copyright &y& Elsevier]