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AbstractThis study proposes a novel model employing nonlinear ordinary differential equations to dissect HCV dynamics. Six distinct population groups are delineated: Susceptible, Treatment, Responder, Non-Responder, Cured, and Fibrosis. A detailed numerical analysis of this model was conducted, tracking the predicted trends over a span of 20 years. The primary objective of this analysis is to assess and confirm the model’s predictive accuracy and its potential to supplant invasive diagnostic methods in monitoring the progression of liver fibrosis. By incorporating various control parameters, namely u1(t),u2(t), and u3(t), the model offers a nuanced perspective on disease progression and treatment outcomes. Parameter u1(t) modulates treatment-induced fibrosis progression, providing a crucial lever for mitigating treatment-related side effects. u2(t) reflects treatment effectiveness, capturing the proportion of responders within the treatment cohort. Meanwhile, u3(t) governs fibrosis progression in non-responders, shedding light on the disease’s natural trajectory without effective treatment. [ABSTRACT FROM AUTHOR]

Fuel cell systems often utilize a hydrogen recirculation system to redirect and transport surplus hydrogen back to the anode, which enhances fuel consumption and boosts the efficiency of the fuel cell. Hydrogen recirculation pumps and ejectors are the most investigated systems. Ejectors are gaining recognition as an essential device in fuel cell systems. However, their application in hydrogen recirculation systems is often limited by a narrow operational range. Therefore, it is advantageous to compile the present condition of the study on various ejector shapes as well as configurations that can accommodate a broader operational range, along with the numerical simulations employed in these studies. This paper begins by examining the structure and operation of ejectors. It then compares and analyzes the latest advancements in research on ejector-based hydrogen recirculation systems with extended operating ranges and reviews the details of numerical simulations of ejectors, which are crucial for the development of innovative and efficient ejectors. This study provides key insights and recommendations for integrating hydrogen ejectors into the hydrogen cycle system of fuel cell engines. [ABSTRACT FROM AUTHOR]

This study undertakes a comprehensive analytical and numerical investigation of the nonlinear Kairat model, a significant evolution equation that governs a wide range of physical phenomena, including shallow water waves, plasma physics, and optical fibers. The Kairat model effectively describes the propagation of nonlinear waves in shallow water, capturing the intricate interplay between nonlinearity and dispersion. It exhibits similarities with well-known nonlinear evolution equations such as the Korteweg-de Vries (KdV) and nonlinear Schrödinger (NLS) equations, thereby offering insights into their common underlying dynamics. To achieve the objectives of this research, we employ the modified Khater (MKhat) and unified (UF) methodologies to derive exact solutions for the Kairat model. Furthermore, the trigonometric-quantic-B-spline (TQBS) scheme is utilized as a numerical technique to verify the accuracy of these derived solutions and validate their applicability within the domain of shallow water wave propagation. This investigation yields a collection of innovative and precise analytical solutions, elucidating the complex nonlinear behavior of the Kairat model and its effectiveness in capturing the dynamics of shallow water waves. Moreover, these analytical solutions are corroborated through numerical simulations conducted using the TQBS scheme, ensuring their reliability and practical significance in understanding and predicting shallow water wave phenomena. The significance of this endeavor lies in its contribution to a deeper understanding of the dynamics of the Kairat model and its potential applications in fields such as coastal engineering, oceanography, and related disciplines. The integration of analytical and numerical techniques offers new perspectives and methodologies for exploring nonlinear evolution equations, potentially benefiting researchers in applied mathematics, physics, and engineering. In summary, this comprehensive analytical and numerical investigation provides novel insights, precise solutions, and a robust foundation for further exploration of the physical implications and applications of the Kairat model in the context of shallow water wave propagation. [ABSTRACT FROM AUTHOR]

In a review paper in this same volume, we present the state of the art on modeling of compressible viscous flows ranging from single‐phase to two‐phase systems. It focuses on mathematical properties related to weak stability because they are important for numerical resolution and on the homogenization process that leads from a microscopic description of two separate phases to an averaged two‐phase model. This review serves as the foundation for Parts I and II, which present averaged two‐phase models with phase exchange applicable to magma flow during volcanic eruptions. Part I establishes a two‐phase transient conduit flow model ensuring: (1) mass and volatile species conservation, (2) disequilibrium degassing considering both viscous relaxation and volatile diffusion, and (3) dissipation of total energy. The relaxation limit of this model is then used to obtain a drift‐flux system amenable to simplification. Here, in Part II, we summarize this model and propose a 1.5D simplification of it that alleviates three issues causing difficulties in its numerical implementation. We compare our model outputs to those of another steady‐state, equilibrium degassing, isothermal model under conditions typical of an effusive eruption at an andesitic volcano. Perfect equilibrium degassing is unreachable with a realistic water diffusion coefficient because conduit extremities always contain melt supersaturated with water. Such supersaturation has minor consequences on mass discharge rate. In contrast, releasing the isothermal assumption reduces significantly mass discharge rate by cooling due to gas expansion, which in turn increases liquid viscosity. We propose a simplified system using Darcy's law and omitting several processes such as shear heating and liquid inertia. This minimal system is not dissipative but approximates the steady‐state mass discharge rate of the full system within 10%. A regime diagram valid under a limited set of conditions indicates when this minimal system captures the ascent dynamics of effusive eruptions. Interestingly, the two novel aspects of the full model, diffusive degassing and heat balance, cannot be neglected. In some cases with high diffusion coefficients, a shallow region where porosity and velocities tend toward zero develops initially, possibly blocking an eventual steady state. This local porosity loss also occurs when a steady‐state solution is subjected to a change in shallow permeability. The resulting shallow porosity loss features many characteristics of a plug developing prior to a Vulcanian eruption. [ABSTRACT FROM AUTHOR]

Burial depth is a crucial factor affecting the forces and deformation of tunnels during earthquakes. One key issue is a lack of understanding of the effect of a change in the buried depth of a single-side tunnel on the seismic response of a double-tunnel system. In this study, shaking table tests were designed and performed based on a tunnel under construction in Dalian, China. Numerical models were established using the equivalent linear method combined with ABAQUS finite element software to analyze the seismic response of the interacting system. The results showed that the amplification coefficient of the soil acceleration did not change evidently with the burial depth of the new tunnel but decreased as the seismic amplitude increased. In addition, the existing tunnel acceleration, earth pressure, and internal force were hardly affected by the change in the burial depth; for the new tunnel, the acceleration and internal force decreased as the burial depth increased, while the earth pressure increased. This shows that the earth pressure distribution in a double-tunnel system is relatively complex and mainly concentrated on the arch spandrel and arch springing of the relative area. Overall, when the horizontal clearance between the center of the two tunnels was more than twice the sum of the radius of the outer edges of the two tunnels, the change in the burial depth of the new tunnel had little effect on the existing one, and the tunnel structure was deemed safe. These results provide a preliminary understanding and reference for the seismic performance of a double-tunnel system. [ABSTRACT FROM AUTHOR]

We consider a mathematical model which describes the equilibrium of two elastic membranes fixed on their boundary and attached to an adhesive body, say a glue. The variational formulation of the model is in a form of an elliptic quasivariational inequality for the displacement field. We prove the unique weak solvability of the model, and then we state and prove a convergence result, for which we provide the corresponding mechanical interpretation. Next, we consider two associated optimization problems for which we provide existence results. Finally, we the present numerical simulation which validates our convergence result. We end this paper with some concluding remarks and an Appendix, in which we present the preliminary material needed in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates a Cahn–Hilliard–Swift–Hohenberg system, focusing on a three-species chemical mixture subject to physical constraints on volume fractions. The resulting system leads to complex patterns involving a separation into phases as typical of the Cahn–Hilliard equation and small scale stripes and dots as seen in the Swift–Hohenberg equation. We introduce singular potentials of logarithmic type to enhance the model's accuracy in adhering to essential physical constraints. The paper establishes the existence and uniqueness of weak solutions within this extended framework. The insights gained contribute to a deeper understanding of phase separation in complex systems, with potential applications in materials science and related fields. We introduce a stable finite element approximation based on an obstacle formulation. Subsequent numerical simulations demonstrate that the model allows for complex structures as seen in pigment patterns of animals and in porous polymeric materials. [ABSTRACT FROM AUTHOR]

Successful pregnancy highly depends on the complex interaction between the uterine body, cervix, and fetal membrane. This interaction is synchronized, usually following a specific sequence in normal vaginal deliveries: (1) cervical ripening, (2) uterine contractions, and (3) rupture of fetal membrane. The complex interaction between the cervix, fetal membrane, and uterine contractions before the onset of labor is investigated using a complete third-trimester gravid model of the uterus, cervix, fetal membrane, and abdomen. Through a series of numerical simulations, we investigate the mechanical impact of (i) initial cervical shape, (ii) cervical stiffness, (iii) cervical contractions, and (iv) intrauterine pressure. The findings of this work reveal several key observations: (i) maximum principal stress values in the cervix decrease in more dilated, shorter, and softer cervices; (ii) reduced cervical stiffness produces increased cervical dilation, larger cervical opening, and decreased cervical length; (iii) the initial cervical shape impacts final cervical dimensions; (iv) cervical contractions increase the maximum principal stress values and change the stress distributions; (v) cervical contractions potentiate cervical shortening and dilation; (vi) larger intrauterine pressure (IUP) causes considerably larger stress values and cervical opening, larger dilation, and smaller cervical length; and (vii) the biaxial strength of the fetal membrane is only surpassed in the cases of the (1) shortest and most dilated initial cervical geometry and (2) larger IUP. [ABSTRACT FROM AUTHOR]

The commercial CFD package Fluent and the Reynolds stress model were used to simulate the hydraulic characteristics with three types of vegetation distribution: longitudinal, interlaced and patch. Each type was aggregated to the middle line l of the water flow in an equal proportion of 0.5, resulting in a total of nine landscape vegetation arrangements. The numerical model was verified and showed a high level of consistency with the experimental comparison; the results indicate the following: (1) As the distribution of landscape vegetation on both sides becomes increasingly concentrated from a loose state to the middle line l of the flow, the flow velocity declines and the maximum Reynolds stress rises, and the greater the Reynolds stress, the more powerful the shear layer, contributing to turbulence, generating mass and momentum exchange and enhancing the vertical transport of momentum. (2) Compared with the gap area, the flow velocity in the vegetation area is smaller, the turbulent kinetic energy is larger and the maximum Reynolds stress of the bottom flow is larger; the larger sediment particles tend to deposit in the gap area, while smaller sediments tend to deposit in the vegetation area. At the same time, the vegetation area is more prone to deposits than the gap area. (3) Under the same vegetation density, whether in the test area or the wake area, the water blocking capacity and the deposition capacity are in the following order: patch distribution pattern > interlaced distribution pattern > longitudinal distribution pattern. [ABSTRACT FROM AUTHOR]

We investigate the numerical calculation of the general Heun equation using Wolfram Mathematica's functions, comparing the numerical solutions with hypergeometric and explicit solutions. This exploration sheds light on the efficacy and accuracy of the numerical algorithm implemented in Mathematica for computing Heun functions. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been significant improvement in the efficiency of hybrid perovskite solar cells (PSCs). When discussing hybrid organic‐inorganic PSCs, it is important to consider stability and toxicity as crucial factors. Additional research is necessary to thoroughly investigate their potential for enhancing market accessibility. Research explores a comprehensive analysis of the photovoltaic performance of CsSnBr3‐based PSCs configurations. Solar cell capacitance simulator‐1D is utilized to study a variety of electron transport layers (ETLs) such as CeO2, TiO2, SnO2, WO3, MZO, ZnO, IGZO, PCBM, WS2, and C60. Examining the impact of different parameters on the performance of CsSnBr3‐based PSCs by precisely modifying spiro‐OMeTAD as a hole transport layer (HTL) is primarily concentrated on. Utilizing a well‐organized arrangement, FTO/ETLs/CsSnBr3/Spiro‐OMeTAD/Au, out of the mentioned ETLs, it has been observed that only four oxides based ETLs (CeO2, SnO2, WO3, and ZnO) are highly compatible and suitable for CsSnBr3‐based PSC. The photovoltaic performance of various ETLs is examined. The power conversion efficiencies of CeO2, SnO2, WO3, and ZnO ETLs are 18.42%, 22.06%, 21.35%, and 21.87% achieved by optimizing various parameters such as thickness, defect density, doping concentration, and electron affinity of all the layers. The validation and simulation findings indicate that CsSnBr3 has significant potential when combined with suitable ETLs and spiro‐OMeTAD as an HTL. [ABSTRACT FROM AUTHOR]

In regular binary eutectic alloys, the shape of two-phase solidification microstructures varies between neighboring eutectic grains. This occurs in particular in alloys that present special orientation relationships (ORs) between the two kinds of crystals. In practice, eutectic grains most often present spatial variations of the crystal orientation of a few degrees. The consequences of this "mosaicity" on the growth dynamics are not clear. We present the first steps of a numerical investigation (boundary-integral method) of the dynamics of the so-called locked-lamellar patterns in the presence of a mosaicity. Realistic alloy parameters were used. We simulated a few pairs of lamellae (periodic boundary conditions) with a smoothly modulated anisotropy of the interphase boundaries in the solid. The pattern evolves then toward a steady-state regime with a uniform lamellar tilt angle, but a spatial modulation of the lamella width. [ABSTRACT FROM AUTHOR]

Rotating detonation engines have been studied experimentally and numerically due to a higher thermal efficiency in theory. Numerical simulations of the flow field inside the engine cost more since the flow is unsteady and contains shock waves, detonation waves, and contact surfaces. Thus, a two-dimensional theoretical study with the method of pressure behind a shock wave or a rarefaction wave as a function of deflection angle of flow was carried out to predict the flow field and reduce the cost. Numerical simulations with a premixed inviscid model were also carried out to verify the theoretical results. The flow field at an equivalence ratio of 0.8 has a curved contact surface, whereas it has a plane contact surface at equivalence ratios of 0.9–1.2 because the RDW is stronger and more stable. Comparisons between the theoretical and numerical results show the theoretical method can be used to obtain a rough flow field inside the RDE, including the pressure and deflection angle of flow behind the shock wave and rarefaction wave. Most of the errors between the numerical and theoretical results are less than 10%. [ABSTRACT FROM AUTHOR]

Based on the 3D heat transfer numerical simulation model, the evolution mechanism of blast furnace cooling plate slag‐hanging behavior with different cooling system structures is analyzed. Cooling plate reduced by 20 mm will not affect its slag‐hanging behavior. Copper cooling plate is best suited for high heat load areas. The vertical spacing of cooling plate is extended by 200 mm, the uniformity of the slag layer decreases by 5%, and the temperature of cooling plate and refractory material increases by 11 and 50 °C. Cooling plate vertical spacing of 510 mm or less can ensure stable slag hanging in the blast furnace. When using a single refractory material, the average uniformity of the slag layer is 95%, 86%, and 79% for graphite brick, semigraphite brick, and sialon‐SiC brick, respectively. Si3N4‐SiC brick cannot operate properly in high heat load areas. The factory can consider setting 125 mm sialon‐SiC brick in the furnace; graphite brick is used outside the furnace lining. The slag layer is well distributed, and the average value of uniformity is about 90%. Even if the slag layer is fully dislodged, the hot surface temperature of the furnace lining is 785 °C, and it can be quickly reslag hanging. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusion During magnetic resonance‐guided focused ultrasound (MRgFUS) surgery for uterine fibroids, ablation of fibrous tissues in proximity to the hips and spine is challenging due to heating within the bone that can cause patients to experience pain and potentially damage nerves. This far‐field bone heating limits the volume of fibroid tissue that is treatable via MRgFUS.To investigate transducer module apodization for improving the ratio of focal‐to‐bone heating (ΔTratio$\Delta T_{\mathrm{ratio}}$) when targeting fibroid tissue close to the hips and spine, to enable MRgFUS treatments closer to the bone.Acoustic and thermal simulations were performed using 3D magnetic resonance imaging (MRI)‐derived anatomies of ten patients who underwent MRgFUS ablation for uterine fibroids using a low‐frequency (0.5MHz$0.5 \ \text{MHz}$) 6144‐element flat fully‐populated modular phased array system (Arrayus Technologies Inc., Burlington, Canada) at our institution as part of a larger clinical trial (NCT03323905). Transducer modules (64elements$64 \ \text{elements}$ per module) whose beams intersected with no‐pass zones delineated within the field were identified, their output power levels were reduced by varying blocking percentage levels, and the resulting temperature field distributions were evaluated across multiple sonications near the hip and spine bones in each patient. Acoustic and thermal simulations took approximately 20min$20 \ \text{min}$ (7min$7 \ \text{min}$) and 1min$1 \ \text{min}$ (30s$30 \ \text{s}$) to run for a single near‐spine (near‐hip) target, respectively.For all simulated sonications, transducer module blocking improved ΔTratio$\Delta T_{\mathrm{ratio}}$ compared to the no blocking case. In just over half of sonications, full module blocking maximized ΔTratio$\Delta T_{\mathrm{ratio}}$ (increase of 82% ±$\pm$ 38% in 50% of hip targets and 49% ±$\pm$ 30% in 62% of spine targets vs. no blocking; mean ± SD), at the cost of more diffuse focusing (focal heating volumes increased by 13% ± 13% for hip targets and 39% ± 27% for spine targets) and thus requiring elevated total (hip: 6% ± 17%, spine: 37% ± 17%) and peak module‐wise (hip: 65% ± 36%, spine: 101% ± 56%) acoustic power levels to achieve equivalent focal heating as the no blocking control case. In the remaining sonications, partial module blocking provided further improvements in both ΔTratio$\Delta T_{\mathrm{ratio}}$ (increased by 29% ± 25% in the hip and 15% ± 12% in the spine) and focal heating volume (decrease of 20% ± 10% in the hip and 34% ± 17% in the spine) relative to the full blocking case. The optimal blocking percentage value was dependent on the specific patient geometry and target location of interest. Although not all individual target locations saw the benefit, element‐wise phase aberration corrections improved the average ΔTratio$\Delta T_{\mathrm{ratio}}$ compared to the no correction case (increase of 52% ± 47% in the hip, 35% ± 24% in the spine) and impacted the optimal blocking percentage value. Transducer module blocking enabled ablative treatments to be carried out closer to both hip and spine without overheating or damaging the bone (no blocking: 42±1mm$42\pm 1 \ \text{mm}$/17±2mm$17 \pm 2 \ \text{mm}$, full blocking: 38±1mm$38\pm 1 \ \text{mm}$/8±1mm$8\pm 1 \ \text{mm}$, optimal partial blocking: 36±1mm$36\pm 1 \ \text{mm}$/7±1mm$7\pm 1 \ \text{mm}$ for hip/spine).The proposed transducer apodization scheme shows promise for improving MRgFUS treatments of uterine fibroids, and may ultimately increase the effective treatment envelope of MRgFUS surgery in the body by enabling tissue ablation closer to bony structures. [ABSTRACT FROM AUTHOR]

The numerical simulation is combined with high‐temperature measurement to study the effects of electromagnetic braking (EMBr) and casting speed on the flow field, the fluctuation of the interface of the steel and slag, the distribution of argon gas bubbles, and the removal ratios of inclusions in the mold with a size of 1050 × 230 mm. The numerical simulation results and the high‐temperature measurement results of the velocities of molten steel at the 1/4 width and center of the thickness near the mold surface are in good agreement. The EMBr can reduce the velocity near the mold surface, the fluctuation of the interface between steel and slag, and the number of argon gas bubbles near narrow walls and decrease the total removal ratio of inclusions from 27.29 to 23.24%. When the casting speed is increased from 1.6 to 2.0 m min−1 with EMBr, the velocity of molten steel near the mold surface is increased. Even under the condition of a high casting speed of 2.0 m s−1, the velocity of molten steel near the surface is still in a reasonable range with EMBr. The total removal ratio of inclusions increases from 20.76 to 23.90%. [ABSTRACT FROM AUTHOR]

Computational and machine learning frameworks have greatly contributed to early diagnosis and rapid therapeutic interventions due to breakthroughs in science and technology. This study aims to develop a mathematical model that utilizes machine learning and integrates both innate and adaptive immunological components to examine the progression of breast cancer. The proposed framework utilizes a set of ordinary differential equations to represent the interactions between breast cancer cells, cytotoxic T lymphocytes, T-helper cells, and macrophages. We used machine learning optimization techniques to enhance the computational framework, enabling accurate modeling of the dynamic alterations occurring in the tumor microenvironment. This approach also considers the different properties and responses of immune cells. Our validated results, obtained using metaheuristic algorithms and sensitivity analysis, provide significant insights into the correlation between the advancement of breast cancer and the innate and adaptive immune systems. This study supports the theory that advanced programming tools may enhance healthcare systems by offering reliable techniques for understanding and possibly controlling the progression of cancer via the manipulation of the immune system. [ABSTRACT FROM AUTHOR]

This study provides an exhaustive exploration of the thermal expansion of low‐temperature argon bubbles in high‐temperature molten steel and the resulting dynamic effects. The energy equation of compressible fluid simultaneously with the volume of fluid model under the Euler framework is solved. The generation and rising behavior of bubbles are validated through rigorous physical water model experiments. Findings reveal that, within a heating time of 0.2–0.45 ms, gas bubbles already complete 65–90% of their internal energy increase. The total heat transfer time and heat transfer coefficient of bubbles exhibit distinctive patterns influenced by the initial diameter and temperature of the bubbles. Specifically, under the conditions studied, bubbles exhibit a total heat transfer time of ≈20–60 ms, accompanied by a heat transfer coefficient ranging from 500 to 2600 W (m2 * K)−1. During the thermal expansion process, gas bubbles experience energy transfer and conversion within the two‐phase flow. This article establishes a dynamic model describing bubble thermal expansion in steel melts based on underwater bubble dynamics’ first principles. The model provides a quantitative depiction of instantaneous changes in bubble size, velocity, and kinetic energy under specific conditions. [ABSTRACT FROM AUTHOR]

This paper develops a second-order explicit predictor–corrector numerical approach for solving a mathematical model on the dynamics of cytokine expressions and human immune cell activation in response to the bacterium staphylococcus aureus (S. aureus). The proposed algorithm is at least zero-stable and second-order accurate. Mathematical modeling works that analyze the human body in response to some antigens have predicted concentrations of a broad range of cells and cytokines. This study deals with a coupled cellular-cytokine model which predicts cytokine expressions in response to gram-positive bacteria S. aureus. Tumor necrosis factor alpha, interleukin 6, interleukin 8 and interleukin 10 are included to assess the relationship between cytokine release from macrophages and the concentration of the S. aureus antigen. Ordinary differential equations are used to model cytokine levels while the cellular responses are modeled by partial differential equations. Interactions between both components provide a more robust and complete systems of immune activation. In the numerical simulations, a low concentration of S. aureus is used to measure cellular activation and cytokine expressions. Numerical experiments indicate how the human immune system responds to infections from different pathogens. Furthermore, numerical examples suggest that the new technique is faster and more efficient than a large class of statistical and numerical schemes discussed in the literature for systems of nonlinear equations and can serve as a robust tool for the integration of general systems of initial-boundary value problems. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical studies on compression behaviour of equal-leg steel angles with bolted connection and subjected to local defect at the bolt hole. To simulate corrosion, a mechanical cutting method was used in the experimental test to increase the diameter of bolt holes, and a total of 18 steel angles were investigated in the study. The parameters considered included the slenderness and the diameter of bolt holes. The slendernesses of steel angles were 80 and 140, and the diameter of bolt holes ranged from 21.5 to 27.5 mm. Additionally, numerical models were established for the steel angles. The accuracy of the numerical model was verified by comparing experimental data with numerical results. Based on the validated numerical model, a parametric analysis was conducted to quantitatively assess the influences of the slenderness and the diameter of bolt holes on the load capacity of specimens against global buckling. Experimental and numerical results showed that the defect at the bolt hole affected the load capacity of specimens when the diameter of the bolt hole was increased to 27.5 mm and the slenderness was not greater than 100. [ABSTRACT FROM AUTHOR]

This special issue focuses on the seismic performance of adjacent interacting masonry structures, particularly in historical European city centers. The AIMS project provided unique data on interacting masonry structures through large-scale shake table tests on two adjacent half-scale stone masonry buildings. The experimental campaign was accomapgnied by a blind prediction study where participants modeled the aggregate's seismic response. Findings highlight challenges in accurately predicting displacement demands and failure modes, providing critical insights for improving future modeling techniques for masonry buildings. [ABSTRACT FROM AUTHOR]

Underwater wireless optical communication (UWOC) systems face challenges due to the significant temporal dispersion caused by the combined effects of scattering, absorption, refractive index variations, optical turbulence, and bio-optical properties. This collective impairment leads to signal distortion and degrades the optical receiver's bit error rate (BER). Optimising the receiver filter and equaliser design is crucial to enhance receiver performance. However, having an optimal design may not be sufficient to ensure that the receiver decision unit can estimate BER quickly and accurately. This study introduces a novel BER estimation strategy based on a Convolutional Neural Network (CNN) to improve the accuracy and speed of BER estimation performed by the decision unit's computational processor compared to traditional methods. Our new CNN algorithm utilises the eye diagram (ED) image processing technique. Despite the incomplete definition of the UWOC channel impulse response (CIR), the CNN model is trained to address the nonlinearity of seawater channels under varying noise conditions and increase the reliability of a given UWOC system. The results demonstrate that our CNN-based BER estimation strategy accurately predicts the corresponding signal-to-noise ratio (SNR) and enables reliable BER estimation. [ABSTRACT FROM AUTHOR]

In this paper, we apply Fourier spectral method to simulate the process of pattern formations of the space variable fractional order Gray–Scott model. This spatially extended reaction–diffusion model is obtained from the standard Gray–Scott model by using the Riesz variable fractional derivative in space. To validate the high efficiency and low computational complexity of the present numerical method, some numerical examples are provided as well as the numerical results are compared with those obtained by other numerical methods. The effects of order with different forms on pattern formation are discussed including a trigonometric function and a polynomial function. Furthermore, the temporal evolution of patterns in the space variable fractional order three-dimensional Gray–Scott model is given. Some interesting process of pattern formations are observed in numerical study which are different from any that have been previously reported. The Fourier spectral method is applicable for the Gray–Scott model with space variable fractional order, and it will be applied to some other space variable fractional order reaction–diffusion models in the future. [ABSTRACT FROM AUTHOR]

As a new mode of marine industry, marine ranching is gradually becoming an important means to promote the high-quality development of marine economy. Meanwhile, the technological innovation of marine ranching enterprises (MREs) can enhance the economic and ecological functions of marine ranching. This paper builds an evolutionary game model including MREs, government and consumers to analyze strategic choices. The results show that: (1) The government's incentive policies play a key role in the initial period of MREs, while the government can gradually eliminate the policies in the mature period of MREs. (2) Government's incentive policies consist of subsidy and tax policies. The subsidy amount should be moderate in order to avoid financial burdens, and the tax policy should be adaptation to different types of MREs. (3) Consumers' preference significantly affects the strategy of MREs innovation. Government subsidies for consumers with different preferences can guide market demand and provide market signals for MREs. This study provides an important reference for MREs to formulate technological innovation strategy and the government to formulate relevant policies. [ABSTRACT FROM AUTHOR]

AbstractRail models may be simplified at different levels in wind tunnel tests and numerical simulations. This work used delayed detached eddy simulations to analyze and compare the aerodynamic loads (drag, side force, lift, and rolling moment), surface pressure, and flow characteristics around a train model placed on subgrades with three different rail models: no-rail, simplified rail, and realistic rail. The simulations were conducted at a large yaw angle of 60°. The mean aerodynamic characteristics of the car bodies and bogies were similar with the simplified rail model and realistic rail model, while those were completely different without the rail model. The difference in aerodynamic loads between the no-rail model and the realistic rail model was as high as 53.1%, whereas the difference between the simplified and realistic rail models was only 7.7%. And for fluctuating aerodynamic characteristics of the train, there was still differences between the cases with the simplified and realistic models. Further, the rail model significantly impacted the flow (such as the velocity, turbulent kinetic energy, and vorticity) around the train, especially under the train, resulting in significant differences in the aerodynamic loads in time and frequency domains. For accurate and precise measurements of mean aerodynamic loads, incorporating a rail model (with the simplified model being sufficient) can improve accuracy by 48.0% and precision by 66.9%. When focusing on fluctuating aerodynamic loads, using a realistic rail model is essential to accurately capture amplitude-frequency characteristics. The rail model setup recommendations outlined in this work aim to enhance the accuracy and reliability of various wind tunnel tests and numerical simulations related to train aerodynamics. [ABSTRACT FROM AUTHOR]

Physical analysis of in situ fire experiments on soils are useful for the estimation of subsurface thermal diffusivity, which is affected by factors such as water, heterogeneity and heating conditions. To address the uncertainties due to these factors, a new data‐processing procedure based on inverse methods was developed and experimentally applied to soils from an archaeological site in the Atacama Desert, Chile. By combining experimental data and numerical simulations, we determined the dominant physical processes arising during the heating. The analysis succeeded in defining practical procedures to obtain a more accurate estimation of the diffusivities, thus reducing the above‐mentioned uncertainties. [ABSTRACT FROM AUTHOR]

AbstractThis paper presents a one-dimensional model that describes fluid flow in lymphangions, the segments of lymphatic vessels between valves, using quasilinear hyperbolic systems. The model incorporates a phenomenological pressure-cross-sectional area relationship based on existing literature. Numerical solutions of the differential equations align with known results, offering insights into lymphatic flow dynamics. This model enhances the understanding of lymph movement through the lymphatic system, driven by lymphangion contractions. [ABSTRACT FROM AUTHOR]

This research presents an advanced fractional-order compartmental model designed to delve into the complexities of COVID-19 transmission dynamics, specifically accounting for the influence of environmental pathogens on disease spread. By enhancing the classical compartmental framework, our model distinctively incorporates the effects of order derivatives and environmental shedding mechanisms on the basic reproduction numbers, thus offering a holistic perspective on transmission dynamics. Leveraging fractional calculus, the model adeptly captures the memory effect associated with disease spread, providing an authentic depiction of the virus’s real-world propagation patterns. A thorough mathematical analysis confirming the existence, uniqueness and stability of the model’s solutions emphasizes its robustness. Furthermore, the numerical simulations, meticulously calibrated with real COVID-19 case data, affirm the model’s capacity to emulate observed transmission trends, demonstrating the pivotal role of environmental transmission vectors in shaping public health strategies. The study highlights the critical role of environmental sanitation and targeted interventions in controlling the pandemic’s spread, suggesting new insights for research and policy-making in infectious disease management. [ABSTRACT FROM AUTHOR]

In this manuscript, we investigate a stochastic version of the Allen–Cahn equation, which is a nonlinear partial differential equation from mathematical physics. The stochastic model considers temporal multiplicative noise in the form of the derivative of the standard Wiener process. The existence and the uniqueness of solutions for this stochastic model is established rigorously using the theory of distributions. As a corollary from these analytical results, some a priori optimal estimates for the solutions of this model are constructed. In this work, we develop reliable numerical schemes which possess similar features as those of the solutions for the analytical model. Moreover, we establish mathematically the von Neumann stability and the consistency for the schemes proposed in this paper. Both the analytical and numerical results derived in this work are computationally verified through some simulations. [ABSTRACT FROM AUTHOR]

Corona discharge is a significant problem in the operation of high-voltage transmission and distribution systems, particularly for polymer insulators. Numerical simulation has become an effective tool for investigating the underlying physical mechanisms and optimizing the design of insulators. In this paper, we present a two-dimensional numerical simulation study on corona discharge plasma affecting the surface behavior of polymer insulators. The simulation was performed with the Comsol Multiphysic software and is based on the finite element method and the fluid plasma model, which considers ionization, recombination, and the transport of plasma species. The numerical results are analyzed to study the spatial and temporal characteristics of the corona discharge and its effect on the surface behavior of polymer insulators. The results show that the electric field is affected not only by the volume charge density but also by the surface charge density, which in turn depends on the densities of the charge carriers migrating on the insulator surface. However, the electric field drops drastically when one or two grading rings are installed. But one grading ring is not enough to limit the discharge. [ABSTRACT FROM AUTHOR]

The current investigation aims to develop a validated numerical model of a confined, swirl-stabilized diffusion flame. This model will assist in designing and optimizing novel combustion chambers while reducing computational costs. To achieve this objective, experimental and numerical studies were conducted on NH3/natural gas combustion using a laboratory-scale burner capable of operating under fuel-flexible conditions. The burner fired 5 kW flames of blended ammonia with natural gas in concentrations up to 100% NH3. The burner's performance for relevant industrial applications was assessed through measurements of axial temperature profiles, exhaust temperature, and gas emissions. Numerical simulations were conducted by employing the commercial CFD software STAR-CCM+ 2020.2.1. Numerical simulations for steady-state were performed using a realizable k- ϵ turbulence model coupled with the EDC (eddy dissipation concept) for combustion. The investigation utilized a 3D periodic domain for the simulations and investigated mesh independence and the influence of the flame dynamics. The burner was able to operate with different fuel mixtures while maintaining stabilized flames under every condition. However, the appearance of increased ammonia slip was observed for 100% NH3 up to 1250 ppm (dry vol.). The present work demonstrates and assesses the readiness and potential of fuel-flexible burners as cost-effective and efficient transitional technologies for integrating ammonia and other sustainable fuels into combustion applications. [ABSTRACT FROM AUTHOR]

Angle profiles belong to the most common steel profiles used in several types of civil engineering structures, such as in lattice towers. Although, in such towers, they are usually considered as axially loaded (truss) members, an additional bending moment develops due to the eccentricity between the point of load application and the gravity center of the profile. Therefore, this paper focuses on the buckling resistance of single-angle members subjected to combined compression and bending. The investigations have been performed through numerical parametrical studies and have been compared to different normative documents where interaction equations are provided. [ABSTRACT FROM AUTHOR]

The regularized lattice Boltzmann method (RLBM) has the advantage of improving the accuracy of numerical simulations without increasing the computational overhead. The RLBM usually uses the standard Cartesian grid in numerical simulation. This paper introduces the multi-layer grid technique, the multi-layer grid has different resolutions, which is also more consistent with the physical laws of the flow field. Based on this, a multi-layer grid regularized lattice Boltzmann method (ML-RLBM) for solving complex flow problems is proposed. The proposed method performs local refinement of the grid on the standard Cartesian grid to achieve a multi-layer grid, which can reduce the computational overhead. In order to realize the local grid refinement easily, this paper adopts the center point format to store the multi-layer grid. The ML-RLBM designs a buffer scheme between different layers of grids, which realizes that only spatial interpolation is required at the interface of different layers of grids without temporal interpolation. The numerical results show that the ML-RLBM has excellent numerical accuracy and numerical stability, and it can effectively reduce the computational cost. [ABSTRACT FROM AUTHOR]

Physical systems comprised of repulsive particles in dissipative media are ubiquitous. The dynamics of the local concentration of repulsive particles can be modeled by a nonlinear diffusion-like equation. To construct these coarse-grained models, it is necessary to determine, based on the local concentration and gradient, the expected force over the dispersed particles. In this work, we consider how the parametrization of the coarse-grained model can be obtained simply by investigating the properties of the steady state of systems presenting a constant concentration profile. We do this through Monte Carlo simulations for these homogeneous states at given temperatures. We use results from molecular dynamics numerical simulations to successfully test the predictions of our continuum model. [ABSTRACT FROM AUTHOR]

Elements of microfluidic systems created by 3D printing offer numerous advantages, such as rapid manufacturing, low cost, and the ability to create complex 3D channel topologies. Their parameters and performance can be quickly adjusted by editing the model loaded into the printer. However, the mechanical properties of polymers used for printing are often poorly documented and can significantly change over time due to aging, relaxation, or creep effects, leading to unexpected behaviour of 3D-printed devices. To address this issue, we performed a complete mechanical characterization of the samples made by 3D printing, including stress relaxation and creep tests, at different time intervals after printing. The determined properties of the material allowed us to model the mechanical and hydrodynamical performance of the 3D-printed microfluidic device, which we demonstrate using an example of a fully printed check valve specially developed for use in microfluidic systems. This approach allows easy quantitative evaluation of the optimal production cycle and lifetime of 3D-printed microfluidic devices. [ABSTRACT FROM AUTHOR]

Careful planning for harbor development is vital for improving the flow of international trade and the economy of any country. Evidently, offshore breakwater reduces wave height approaching a harbor, but it is necessary to be designed as efficiently as possible. This study analyzes the development of Al-Max area as a promising new harbor connecting Alexandria's Western Harbor and El-Dekheila harbor. This development is an important step towards improving the capacity and efficiency of Alexandria's ports in order to expedite imports and exports. These objectives align with multiple UN Sustainable Development Goals (SDGs), given the fact that the specific actions and measures taken within the middle port project will determine the extent of their impact on each goal. Necessary information, such as the bathymetric map and annual wave climate were collected and analyzed. The Delft3D FM software package was used for carrying out the numerical simulations. Sheltering the whole area of the port through establishing several new offshore breakwaters, which are going to be installed at a number of locations using best-in-class designs, will partially enclose the basin containing the three harbors, while considering the existing channel of navigation. The results of the simulation prove that breakwaters with the maximum segment length and minimum clearance for navigation channels could reduce the wave height significantly. [ABSTRACT FROM AUTHOR]

We previously proposed that the optical centroid efficiency (OCE) might be a preferred figure-of-merit to the enclosed energy of a rectangular pixel (EOD) for an instrument subject to unpredictable environmental jitter and alignment conditions. Here we follow the same symbols for the corresponding quantities, particularly the width of the pixel as being equal to 2d. Here we analyze the performance of the OCE vs. the EOD for the three Seidel primary aberrations of an optical component: spherical, coma, and astigmatism, plus defocus. We show that the OCE has an approximate U-shape when graphed against the EOD, for the aberrations ranging from 0 to 1.25λ. We conclude that for pixels larger than 2d = 3λF/#, a small pixel will feature better performance when expecting jitter, misalignment, and other environmental and unpredictable conditions. When evaluating the performance of low-aberration instruments in dynamic and unpredictable environments, the choice of the lager pixel 2d = 7λF/# might be advantageous. Its selection will result in the deterioration of image resolution. [ABSTRACT FROM AUTHOR]

The objective of this study, which is divided into two parts, is twofold: to address long-standing challenges in the sensing of atmospheric turbulence-induced wavefront aberrations under strong scintillation conditions via a comparative analysis of several basic scintillation-resistant wavefront sensing (SR-WFS) architectures and iterative phase retrieval (IPR) techniques (Part I, this paper), and to develop a framework for the potential integration of SR-WFS techniques into practical closed-loop non-astronomical atmospheric adaptive optics (AO) systems (Part II). In this paper, we consider basic SR-WFS mathematical models and phase retrieval algorithms, tradeoffs in sensor design and phase retrieval technique implementation, and methodologies for WFS parameter optimization and performance assessment. The analysis is based on wave-optics numerical simulations imitating realistic turbulence-induced phase aberrations and intensity scintillations, as well as optical field propagation inside the SR-WFSs. Several potential issues important for the practical implementation of SR-WFS and IPR techniques, such as the requirements for phase retrieval computational grid resolution, tolerance with respect to optical element misalignments, and the impact of camera noise and input light non-monochromaticity, are also considered. The results demonstrate that major wavefront sensing requirements desirable for AO operation under strong intensity scintillations can potentially be achieved by transitioning to novel SR-WFS architectures, based on iterative phase retrieval techniques. [ABSTRACT FROM AUTHOR]

Natural rock fractures often exhibit non-matching characteristics at certain scales, leading to uneven aperture distributions that significantly affect fluid flow. This study investigates the impact of the mismatch between the upper and lower surfaces on the flow through three-dimensional rough fractures. By applying fractal theory, a rough upper surface of the fracture is generated, and different degrees of mismatch are introduced by adding random noise to this surface. This approach enables the construction of a variety of three-dimensional rough fracture flow models. Numerical simulations, which involve directly solving the Navier-Stokes equations, are used to simulate flow through a rough single fracture, assessing the effects of various degrees of mismatch between the surfaces. The study also examines how the inclusion of the matrix alters flow characteristics. The results demonstrate that the Forchheimer equation accurately describes the nonlinear flow behavior in fractures with different degrees of mismatch. The increased mismatch intensifies the uneven distribution of fracture apertures, causing the flow velocity to shift from uniform to discrete and the streamlines to become increasingly curved. The overall tortuosity of the flow path increases and the formation of 'concave' and 'convex' areas leads to vortex zones, promoting nonlinear seepage. The correlation between both viscous and inertial permeability with the degree of mismatch is negative, whereas the impact of matrix permeability on the flow capacity of the fracture shows a positive correlation with a mismatch. [ABSTRACT FROM AUTHOR]

In this paper, we considered a stochastic model of chemical reactive flows acting through porous media under the influence of nonlinear external random fluctuations, where the interchanges of chemical flow across the skeleton’s surface are represented by a nonlinear function. We studied the existence and uniqueness of strong probabilistic solutions for the model under consideration. We also show the positivity for the concentration of the solute in the fluid face as well as the concentration of reactants on the surface of the skeleton under extra reasonable assumptions on the data. Initially, we approximated the solution of the nonlinear stochastic diffusion equation using Galerkin’s approximation, and obtained important bound estimates along with probabilistic compactness results. Thereafter, we passed the limit and obtained a weak probabilistic solution. This was followed by the path-wise uniqueness of the solution, which leads to the existence and uniqueness of strong probabilistic solutions as a result of Yamada-Watanabe’s theorem. Finally, we discuss some important numerical applications such as Langmuir and Freundlich kinetics using the extended stochastic nonconforming finite element method to illustrate the efficiency of this approach and compare it to the deterministic approach in both cases. Let us mention that well-posedness, positivity, and numerical simulations have not been considered so far for such a nonlinear stochastic model [ABSTRACT FROM AUTHOR]

Buildings are one the largest energy-consuming sectors in the world, and it is crucial to find solutions to reduce their energy consumption. One way to evaluate these solutions is using building simulation software, which provides a comprehensive perspective. In this article, using DesignBuilder software (v 6.1), the effect of using phase-change materials (PCMs) on the external walls and ceiling of the Department of Mechanical Engineering of Shahid Beheshti University (Tehran, Iran) has been investigated. The methodology involves the use of a layer of PCMs for three locations: (1) on the walls; (2) on the ceiling; and (3) on both the walls and ceiling, with/without PV panels, which leads to seven scenarios (alongside the reference one). The result shows that using PCMs has a greater impact on the heating load than the cooling one and is more effective on ceilings than walls. For the simultaneous use of PCMs in the ceilings and walls, the heating and cooling loads, in comparison with the initial condition of the building, are reduced by 24%, and 12%, respectively. When using solar panels, the heating load increases by 12.6%, and the cooling load decreases by 8.6%, whereas the total energy consumption of the building is fairly constant when using both PV panels and PCMs. In these last conditions, the primary evaluated values shifted significantly. Notably, CO2 emissions saw a nearly 50% reduction, making the simultaneous use of PV panels and PCMs on both walls and ceilings the best performance option. [ABSTRACT FROM AUTHOR]

Crosswind and angle of attack are critical factors that influence the safe operation of civil aviation engines, which are also essential criteria in the certification of civil engine airworthiness. Conducting research on the effects and mechanisms of angle of attack and crosswind on the integrated characteristics and flow field of nacelle and fan holds significant engineering value. In this study, a high-bypass-ratio turbofan engine serves as the research subject, and the influence of crosswind and angle of attack coupling on the nacelle intake and fan components is analyzed using numerical simulations. The numerical research findings indicate that both individual angle of attack and crosswind, as well as their combination, lead to a specific range of total pressure distortion in the inlet. At an angle of attack of 25°, the extent and degree of circumferential total pressure distortion formed on the aerodynamic interface exhibit minor variations under different crosswind inflow conditions. Under two operating conditions involving left crosswind and right crosswind, both characterized by an angle of attack of 25° and a wind speed of 20 m/s, the combined effects of crosswind and angle of attack on the fan and outlet guide vane (OGV) components are mainly concentrated at the blade tip. These influencing factors collectively lead to total pressure distortion in the inlet flow field, resulting in the interaction between tip leakage flow and passage shock waves. At the same angle of attack, there are differences in the impact of total pressure distortion caused by crosswinds in two directions on the fan. Under the same operating conditions, the total pressure distortion induced by the right crosswind has a greater impact on OGV. [ABSTRACT FROM AUTHOR]

The recycling and utilization of waste tires has attracted widespread attention in recent years. To solve the problems related to the land occupation and pollution of waste tires, this study proposed a method of combining tire strips and the tire-derived aggregate (TDA) reinforcements used in embankments. The goal was to explore the impacts of composite reinforcements on the bearing capacities of embankments. In this study, the bearing characteristics and influencing factors of reinforced embankments with or without TDA filler and tire strips were examined in indoor tests using particle image velocimetry technology. The model test results showed that when compared with the unreinforced condition, the addition of TDA and mesh tire strips increased the bearing capacities of the embankments by 25% and 65%, respectively. The composite reinforcement composed of TDA and mesh tire strips had the most significant effect on improving the bearing capacity, which was 1.81 times that of the unreinforced condition. It was found that the displacements of the embankment slopes became smaller and more uniform under the conditions of combined reinforcements. Furthermore, this study utilized numerical simulations to examine the effects of the tire strip layers, soil strength, TDA reinforcement thicknesses, and slope gradients on the bearing performances of embankments. The numerical simulation results indicated that TDA filler and tire strip reinforcements had greatly improved the bearing capacities of the examined embankments. Therefore, the results of this study verified the feasibility of tire strip and TDA composite reinforcement methods and provided a basis for further research and engineering applications. [ABSTRACT FROM AUTHOR]

The study aims to simulate the stage-wise, year-wise mine seepage predictions and the corresponding impact on the groundwater regime (drawdown and heads) in accordance with the approved mine plan for certain coal mines in Central India. To that end, the optimized and efficient watershed area of 997.61 km2 has been delineated by using ArcGIS software and was synthesized in a finite difference numerical model with the concept of 21 layers (multi-layered aquifer system) encompassing six working mines. Initially, the groundwater-flow model was constructed for the simulation of groundwater conditions during May 2022 which shows a good model fit of the observed and simulated water levels, with the majority of the data lying close to the 1:1 line as indicated by an RMS value of less than 5 m. Then, the zone budget of different forecast scenarios reveals that the inflows into the various mine excavation area are: 13,733 (Gevra OC), 12,732 (Kusmunda OC), 8569 (Dipka OC), 8308 (Surakchar UG), 8018 (Manikpur OC), and 7511 (Balgi UG) m3/day. The zone of influence defined by zero drawdown extends up to 1.22 km to the NW of Kusmunda OCP, 2 km to the east of Dipka OCP, and 1.25 km to the SW from the quarry surface boundary of Gevra OCP and is negligible, i.e. up to < 0.5 km, in the western side with the predicted drawdown of 10 m within the project lease area. However, the progressive recovery of water levels will start in accordance with the closure of mines and the cone of depressions due to mine dewatering tend to vanish by 2050. The simulations suggest that mining activities have impacted neither the flow system of the Hasdeo River (effluent stream) nor the aquifers that are interacting with the river, as the river has not contributed any groundwater flows in to these mining areas. [ABSTRACT FROM AUTHOR]

The potential of folding wing unmanned aerial vehicles (UAVs) in enhancing the adaptability of complex missions is substantial. Analyzing the aerodynamic characteristics of these UAVs is vital for optimizing the design of their folding wing configuration and airfoil shape. In this study, a model of a Z-shaped folding wing UAV was established with the objective of enhancing UAV maneuverability. An integrated vortex lattice method (VLM) was employed to analyze the aerodynamic characteristics of the Z-shaped folding wing and numerical simulations were utilized to validate the obtained results, which prove the effectiveness of the integrated VLM in studying aerodynamic characteristics at a high angle of attack of the Z-shaped folding wing UAV. This is a new way to reduce computation time while maintaining accuracy to calculate such complex folding structures in high fidelity. Furthermore, the Z-shaped folding wing configuration demonstrates enhanced maneuverability at high angles of attack, and a Simulink flight simulation model based on the aerodynamic coefficients of the Z-shaped folding wing verifies this property. This analysis can properly predict the post-stall characteristics for the Z-shaped folding wing UAV to ensure the safety of the vehicle during flight. [ABSTRACT FROM AUTHOR]

The article addresses a critical and timely issue: improving safety in underground coal mining. The primary objective of the paper was to develop a research methodology based on modelling studies to identify and assess the state of methane hazards during mining operations. To achieve this, structural modelling of the physical and chemical phenomena occurring in mining regions was conducted using Computational Fluid Dynamics. The core research was performed using the finite volume method on a real longwall exploitation site ventilated by a Y-system. This approach enabled the determination of methane and oxygen concentration distributions in the mining region and goafs, treated as a porous and permeable medium. Based on these findings, potential fire and/or methane explosion hazard zones were identified in the goaf. The model test results underwent a validation process, comparing them with actual measurements. The determined errors were within an acceptable range, confirming the accuracy of the developed model of the mining region and the phenomena within it. Furthermore, the model was used to predict the locations of zones at risk of fire and/or methane explosion in the goafs, particularly in areas with potentially increased gas emissions. The results clearly demonstrate the significant potential of using model studies to diagnose and forecast methane hazards in underground mining operations. Identifying these potential danger zones allows for the implementation of preventive measures to reduce the likelihood of dangerous incidents. [ABSTRACT FROM AUTHOR]

Bright‐band defects frequently occur on as‐cast strips in the twin‐roll strip‐casting process, particularly at low‐casting speeds, with intervals of ≈200 mm. Additionally, the cast‐rolling force also exhibits minor fluctuations. With increasing casting speeds, the spacing between bright‐band defects widens, and the severity of these defects diminishes. When the casting speed reaches a certain threshold, defects almost entirely disappear. Detailed analysis of the underlying causes of this phenomenon is essential for effectively preventing defect formation. In this study, the numerical simulation method is employed to analyze casting rolls’ thermal deformation and the melt pool's solidification behavior, based on the production site equipment and process conditions. The causes of defects in as‐cast strips are thoroughly analyzed based on simulation results, in conjunction with variations in the cast‐rolling force. In this study, it is demonstrated that the thermal deformation of casting rolls and the position of the solidification endpoints collectively contribute to the fluctuations in cast‐rolling force and are the primary causes of bright‐band defects. Fundamental principles for preventing defects are provided based on actual on‐site production. Furthermore, simulation results contribute to establishing a theoretical basis for selecting process parameters and controlling cast‐rolling force during production. [ABSTRACT FROM AUTHOR]

We introduce a new compartmental model aimed at examining the dynamics of user adoption and abandonment within online social networks. Our model encompasses two abandonment dynamics: infectious abandonment caused by internal influences from individuals who have already left the network and noninfectious abandonment triggered by mass media, advertisements, or the introduction of new products. We verify the model's validity and explore the existence and stability of its equilibria. To confirm our theoretical framework, we conduct extensive numerical simulations. We demonstrate the model's effectiveness by fitting it to historical data on Facebook's daily active users. Finally, we utilize the derived model parameters to forecast the future numbers of active users on Facebook. [ABSTRACT FROM AUTHOR]

The oxygen effective diffusion and proton effective conductivity tensors of a cathode catalyst layer (CCL) are computed using a two-scale approach on CCL microstructure three-dimensional images obtained by focused ion beam-scanning electron microscopy (FIB-SEM) after reconstruction of the ionomer distribution. The results show that the obtained tensors are not isotropic. It is also found that some off-diagonal components are not negligible in the case of the proton effective conductivity tensor. The simulations confirm that Knudsen diffusion has a significant impact on oxygen diffusion. The results are comparable to those obtained in previous works on synthetic images as regards the oxygen effective diffusion through-plane component but differ as regards the proton conductivity through-plane component. Contrary to previous works using synthetic images which tend to underestimate the proton conductivity, they are globally in better agreement with experimental data. The results also show that the effective proton conductivity is heterogeneous at the scale of the computational domains typically considered in several previous works due to the variability in the ionomer distribution at this scale. The impact of liquid water in the primary pores on the proton transport is explored and found to have a significant impact. • The oxygen effective diffusion tensor is computed from 3D digital images of a PEMFC catalyst layer (CL). • The proton effective conductivity tensor is computed from 3D digital images of the CL microstructure. • Liquid water in the primary pores has a noticeable impact on the proton transport. • Results on the proton transport validate the considered ionomer spatial distribution. [ABSTRACT FROM AUTHOR]

Spatiotemporally resolved data on photovoltaic (PV) power generation are very helpful to analyze the multiple impacts of this variable renewable energy on regional and local scales. In the absence of such disaggregated data for Germany, numerical simulations are needed to obtain the electricity production from PV systems for a time period and region under study. This manuscript presents how a physical simulation model, which uses open access weather and plant data as input vectors, can be created. The developed PV model is then applied to an ensemble of approximately 1.95 million PV systems, consisting of ground-mounted and rooftop installations, in order to compute their electricity production in Germany for the year 2020. The resulting spatially aggregated time series closely matches the measured PV feed-in pattern of Germany throughout the simulated year. Such disaggregated data can be applied to investigate the German PV power generation landscape at various spatiotemporal levels, as each PV system is taken into account with its technical data and the weather conditions at its geo-location. Furthermore, the German PV power generation landscape is presented as detailed maps based on these simulation results, which can also be useful for many other scientific fields such as energy system modeling. [ABSTRACT FROM AUTHOR]