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This paper proposes a novel damage index for railway bridges based on synchronous strain and displacement data collected at the passage of trains. The approach identifies a transformation operator that converts strains into displacements in a data‐driven fashion without prior structural knowledge and with no parameter selection. The displacement prediction error is proposed as a robust damage index, insensitive to the vehicle loads and temperature effects. Numerical simulations and data generated through the calibrated finite element model of a steel truss bridge showcase the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Highlights The 3D woven spacer fabric lightweight composites (WSFC) show promising applications in construction, transportation and aerospace. In this study, the 3D WSFC with different structural variations (e.g., layer thicknesses, stacking and face layer thickening) were designed and fabricated. The fracture strengths of single‐layer WSFC in the weft direction with layer thicknesses of 5, 10 and 15 mm were 54.4, 14.3, and 5.4 MPa. In the weft direction, the fracture strengths of double‐ and triple‐stacked 3D WSFCs were 30.6 and 21.7 MPa, which improved 1.1 times and 3.0 times as compared with those of original single‐layer 3D WSFCs, respectively. The double‐ and triple‐stacked WSFC also had large flexural deformation. The 3D WSFC with double‐layer misaligned stacking had the similar flexural strengths in both directions, which obviously reduced the performance differentiation of 3D WSFC in different directions. With the addition of face layer fabric, the mechanical performances of 3D WSFC were notably enhanced, and the damage modes were changed from brittle failure to ductile failure. Furthermore, a multi‐scale model of 3D WSFC with different structural variations was developed for numerical simulation to analyze the stress distribution and damage mechanism. Stacking design obviously improves mechanical properties of 3D WSFC. WSFC with misaligned stacking has similar flexural strengths. A multi‐scale elastic–plastic damage model for 3D WSFC is established. Damage modes of WSFC are changed with the stacking method. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Various catheter designs are appearing for Pulsed Field Ablation (PFA). It is unclear if they differ in terms of safety and efficiency. PFA studies have reported hemolysis, kidney injury, high troponin, among other side effects.Using a CT‐derived computer model, we compared catheter designs using two metrics: (1) efficiency: power delivered to an atrial wall target, expressed as a percent of total generator power; and (2) safety: electric current to achieve 90% transmurality (since more energy causes more collateral effects), as well as the corresponding electrode current density (ECD), a heat and bubble metric. The following catheter designs were compared: penta‐spline basket, Nitinol spheres (focal 9 mm and large 1‐shot), circular, balloon, and flex‐circuit. Target was a 6 × 47 mm circumferential segment of atrial wall at LPV antrum. Transmurality was defined as percent of target having >600 volts per centimeter (V/cm) electric field needed for electroporation.Efficiency was 0.9, 1.4, 2.7, 5.9, 10, and 12% for the large 1‐shot and 9 mm Nitinol spheres, penta‐spline, circular, flex spline, and balloon catheters, respectively. Regarding safety, currents for 90% transmurality were 70, 39,36,12.5, 5.3, and 4 Amps for the same respective catheters, with less being safer. ECD was 124, 25, 74, 83, 41, and 31 A/cm2, respectively.Computer models demonstrated a remarkable range in efficiency among catheters studied. Those having less atrial blood exposure had the highest efficiencies, with factors of up to 13X more efficiency compared to exposed ones. Higher efficiency designs have less collateral current and are safer. Confirmatory in‐vivo studies are required. [ABSTRACT FROM AUTHOR]

This paper considers a two‐species chemotaxis system with chemical signaling loop and Lotka–Volterra competition kinetics under the homogeneous Newman boundary condition in smooth bounded domains. The global existence and boundedness of solutions for the parabolic–elliptic/parabolic–parabolic system are established. In the strong competition case, the global stability of the semitrivial constant steady state is obtained under certain parameter conditions. Linear analyzes and numerical simulations demonstrate that chemical signaling loop can significantly impact population dynamics, and admit the coexistence in the exclusion competitive case, including nonconstant steady states, chaos, and spatially inhomogeneous time‐periodic types. [ABSTRACT FROM AUTHOR]

The atrioventricular node (AVN) is a crucial component of the cardiac conduction system. Despite its pivotal role in regulating the transmission of electrical signals between atria and ventricles, a comprehensive understanding of the cellular electrophysiological mechanisms governing AVN function has remained elusive. This paper presents a detailed computational model of mouse AVN cell action potential (AP). Our model builds upon previous work and introduces several key refinements, including accurate representation of membrane currents and exchangers, calcium handling, cellular compartmentalization, dynamic update of intracellular ion concentrations, and calcium buffering. We recalibrated and validated the model against existing and unpublished experimental data. In control conditions, our model reproduces the AVN AP experimental features, (e.g. rate = 175 bpm, experimental range [121, 191] bpm). Notably, our study sheds light on the contribution of L‐type calcium currents, through both Cav1.2 and Cav1.3 channels, in AVN cells. The model replicates several experimental observations, including the cessation of firing upon block of Cav1.3 or INa,r current. If block induces a reduction in beating rate of 11%. In summary, this work presents a comprehensive computational model of mouse AVN cell AP, offering a valuable tool for investigating pacemaking mechanisms and simulating the impact of ionic current blockades. By integrating calcium handling and refining formulation of ionic currents, our model advances understanding of this critical component of the cardiac conduction system, providing a platform for future developments in cardiac electrophysiology. Key points: This paper introduces a comprehensive computational model of mouse atrioventricular node (AVN) cell action potentials (APs).Our model is based on the electrophysiological data from isolated mouse AVN cells and exhibits an action potential and calcium transient that closely match the experimental records.By simulating the effects of blocking specific ionic currents, the model effectively predicts the roles of L‐type Cav1.2 and Cav1.3 channels, T‐type calcium channels, sodium currents (TTX‐sensitive and TTX‐resistant), and the funny current (If) in AVN pacemaking.The study also emphasizes the significance of other ionic currents, including IKr, Ito, IKur, in regulating AP characteristics and cycle length in AVN cells.The model faithfully reproduces the rate dependence of action potentials under pacing, opening the possibility of use in impulse propagation models.The population‐of‐models approach showed the robustness of this new AP model in simulating a wide spectrum of cellular pacemaking in AVN. [ABSTRACT FROM AUTHOR]

This historical review addresses the issues of the evaluation and testing of hydrological models, with a focus on rainfall–runoff models. After a discussion of the general philosophies of hydrological modeling, nine different philosophies of model evaluation are considered, focusing on the period of modeling on digital computers since the 1960s. In addition, some discursions to discuss the definitions of calibration and validation, how much data is needed for model calibration, equifinality and uncertainty, probabilities and possibilities, the evaluation of model ensembles, and model benchmarking. The paper finishes with a final discursion on the philosophical problem of induction.This article is categorized under: Science of Water > Methods Science of Water > Hydrological Processes [ABSTRACT FROM AUTHOR]

ABSTRACT Measurement errors are ubiquitous in all experimental sciences. Depending on the particular experimental platform used to acquire data, different types of errors are introduced, amounting to an admixture of additive and multiplicative error components that can be uncorrelated or correlated. In this paper, we investigate the effect of different types of experimental error on the recovery of the subspace with principal component analysis (PCA) using numerical simulations. Specifically, we assessed how different error characteristics (variance, correlation, and correlation structure), loading structures, and data distributions influence the accuracy to estimate an error‐free (true) subspace from sampled data with PCA. Quality was assessed in terms of the mean squared reconstruction error and the congruence to the error‐free loadings, using the pseudorank and adjusting for rotational ambiguity. Analysis of variance reveals that the error variance, error correlation structure, and their interaction with the loading structure are the factors mostly affecting quality of loading estimation from sampled data. We advocate for the need to characterize and assess the nature of measurement error and the need to adapt formulations of PCA that can explicitly take into account error structures in the model fitting. [ABSTRACT FROM AUTHOR]

In this paper, we consider an estimation problem of sideslip angle and cornering stiffness of a vehicle from measurements of yaw rate, lateral acceleration and steering angle. Firstly, a vehicle dynamical model is expressed as a linear parameter‐varying system with cornering stiffness as uncertain parameters. Then, we show a method to estimate the parameters and the state based on moving horizon estimation. We provide a simple algorithm to solve the estimation problem. The effectiveness of the estimation method is evaluated through numerical simulations. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we investigate the effectiveness of incremental relaying (IR)‐based underlay cognitive nonorthogonal multiple access (CNOMA) system with maximal ratio combining (MRC). Considering imperfect successive interference cancelation (i‐SIC), we derive analytical expressions for the outage probabilities experienced by the secondary users (SUs) and the system outage probability of the IR‐CNOMA system. We also derive the analytical expression for the outage probability of far SUs by considering IR‐CNOMA system with MRC. The maximum transmit power constraint of the secondary nodes and the interference threshold constraint of the primary receiver are considered in the analysis. We also evaluate the system throughput of IR‐CNOMA network. We also derive outage and throughput expression for the traditional cooperative relaying‐based CNOMA system (CR‐CNOMA) for the purpose of comparison. We derive analytical expression for the asymptotic outage probability and the asymptotic system outage probabilities of the SUs of IR‐CNOMA system. Further, we derive expressions for the optimal power allocation (OPA) factor at the secondary source that minimizes the asymptotic system outage probability of the IR‐CNOMA system. Through numerical and simulation investigations, we demonstrate that the system outage probability significantly lowers when the OPA factor is selected based on the criteria outlined in this work. It can be observed from the results that the IR‐CNOMA system outperforms the conventional CR‐CNOMA system in terms of outage probabilities and throughput. The outage probability is further reduced when IR‐CNOMA system with MRC is considered for the far SUs. [ABSTRACT FROM AUTHOR]

In this paper, the influence of tunnel cross‐sectional aspect ratio on the ceiling temperature profile and mass flow rate (MFR) of ceiling jet is studied theoretically and numerically, and 13 tunnel cross sections with different aspect ratios (ξ) are considered. A total of 26 full‐scale numerical simulation cases are conducted using Fire Dynamics Simulator, and small‐scale experiments are used to verify the accuracy of the simulations. Results show that the maximum ceiling temperature is more sensitive to the tunnel height and decreases with increasing aspect ratio, which can be divided into two regions, ξ <1 and ξ ≥1. When ξ ≥1, the maximum ceiling temperature varies more linearly. The initial locations of the one‐dimensional spread for the tunnel with different tunnel cross‐sectional aspect ratios are similar, which are concentrated at 15–20 m from the fire source when taking the MFR increase rate of 0.001 as the criterion. By introducing the sectional coefficient, the MFR model and temperature attenuation model of ceiling jet are developed for the tunnels with ξ <1 and ξ ≥1, respectively. The results of this paper could provide definite reference value for the smoke control in tunnel fires. [ABSTRACT FROM AUTHOR]

Grain boundary (GB) migration plays a crucial role in the microstructural evolution of polycrystalline materials, particularly in fine‐grained materials. This migration can be driven by shear forces or by an energy jump across a GB. Interestingly, GB migration processes during cyclic loading deformations have been observed to be fully reversible. This study focuses on understanding the impact and importance of shear driving forces, the free energy difference across a GB, and lattice dislocations on GB migration. These factors are key points for gaining deeper insights into the underlying mechanisms of GB migration. In this work, GB migration in cyclic loading deformations is demonstrated, and it is emphasized that it clearly depends on both the shear driving forces (attributed to the motion of disconnections) and the energy differential across the GB. Two cyclic micro‐experimental methods, accompanied by analytical and numerical simulations, have been employed to investigate the role of shear stresses and energy jump‐driving forces in GB migration. This investigation provides clear experimental evidence that GB migration, in particular for a high‐angle GB, is dependent on both stress and energy driving forces. [ABSTRACT FROM AUTHOR]

It is well known the Oseen iteration for the stationary Navier–Stokes equations is unconditionally stable. However, it is a coupled type scheme where the velocity u$$ \boldsymbol{u} $$ and pressure p$$ p $$ are coupled together at each iteration. By treating pressure p$$ p $$ explicitly would lead to a decoupled iteration, but this treatment is unstable. In this article, we construct a decoupled and unconditionally stable iteration method to solve the stationary Navier–Stokes equations by adopting the pressure projection method to the temporal disturbed Navier–Stokes system whose solution approximates the steady state solution over time (t→+∞$$ t\to +\infty $$). We also rigorously prove its unconditional stability. Numerical simulations demonstrate that our iterative method is more efficient and stable than the extensively used T‐S and Oseen iterations, and could solve the fluid flow with high Reynolds number. [ABSTRACT FROM AUTHOR]

In this paper, we consider a singular diffusive predator–prey model with Beddington–DeAngelis functional response, employing geometric singular perturbation theory and Bendixson's criteria. Our investigation revolves around transforming the reaction–diffusion equation into a multi‐scale four‐dimensional slow–fast system with two different orders of small parameters. Through once singular perturbation analysis, our focus shifts towards exploring the existence of heteroclinic orbits in a three‐dimensional system. We analyze these dynamics through the perspective of the Fisher–KPP equation in two limit cases. In the first case, only the normal to the two‐dimensional slow manifold is unstable. This allows for the deduction of existence of heteroclinic orbits in the three‐dimensional system through investigating the dynamics on the two‐dimensional slow manifold. Consequently, we obtain both monotonic traveling fronts and non‐monotonic fronts with oscillatory tails. In the second case, the normal to the one‐dimensional slow manifold exhibits both stable and unstable directions, then it is impossible to restrict the dynamics of the three‐dimensional system entirely to the slow manifold. Instead, we integrate the slow orbits of the reduced system with the fast orbits of the layer system to construct a singular heteroclinic orbit. According to Fenichel's theorem, we discover the existence of exact heteroclinic orbits of three‐dimensional system and derive the monotonic traveling fronts under weaker parameter conditions. Additionally, we also discuss the nonexistence of traveling fronts. Finally, we demonstrate our theoretical results with numerical simulations. [ABSTRACT FROM AUTHOR]

To study the influence of different geological and mining factors on the decompression effect of protective layer mining, a numerical simulation was carried out using FLAC3D numerical software. Taking the Hulusu coal mine as the engineering background, numerical simulation studies were carried out under different mining heights, working face lengths, interlayer lithologies and layer spacing by using FLAC3D numerical software, and the effects of different geological and mining factors on the degree of decompression and the scope of decompression were quantitatively investigated through the control of single‐factor variables. The results show that: the stress at the critical depth of impact ground pressure is 16.44 MPa, and the coefficient of unloading degree C = 0.5 is the indicator of sufficient unloading; the unloading effect of the protected layer decreases with the increase of layer spacing, lithological strength, and length of the working face, and increases with the increase of mining height; the geological and mining parameters of the protected layer show a functional relationship with the critical depth of the unloading, and the order of the influence of pressure relief effect is layer spacing > mining height > interlayer lithology > working face length. The results of the study are very important for the determination of the mining parameters of the protective layer, the estimation of the protective effect, and the design of the management programme of impact pressure. [ABSTRACT FROM AUTHOR]

Pelton turbines functioning in sandy river environments often encounter difficulties due to the swift movement of sediment particles, leading to erosion and damage to overflow components. These challenges can result in operational instability, particularly noticeable in large turbines. Pressure pulsation is crucial for turbine stability, and alterations in overflow component profiles caused by sediment erosion can worsen pressure pulsations. This study utilizes numerical simulations to analyze turbine pressure pulsations based on surface profile changes of runner buckets after 2 and 4 years of sediment erosion in a single 500 MW large‐scale Pelton turbine. Our findings reveal that erosion leads to a gradual decrease in pressure pulsation along the bucket's splitting edge from the notch to the root. After 4 years of erosion and wear, the relative pressure pulsation amplitude in the root region increased by more than 530%. Additionally, changes occur in the thickness of the water film in the erosion area on the working surface, disrupting the flow pattern and generating more vortices. This occurrence intensifies the relative pressure pulsation amplitude and reduces bucket stability. The study findings highlight the significant impact of sediment erosion on Pelton turbine pressure pulsation, posing a considerable risk to the unit's operational stability and safety. [ABSTRACT FROM AUTHOR]

In this paper, we propose and study a discretized one‐predator two‐prey system along with prey refuge and Michaelis–Menten‐type prey harvesting. The interaction among the species is considered as Holling type III functional response. Firstly, existence and local stability of all the fixed points are derived under certain parametric conditions. Furthermore, a special consideration is made to global asymptotic stability of the interior fixed point. Then, we have shown that the system undergoes different types of bifurcations including transcritical bifurcation, flip bifurcation, and Neimark–Sacker bifurcation by using center manifold theorem, bifurcation theory, and normal form method. Also, Feigenbaum's constant of the system is calculated. It is observed that both harvesting and refuge have a stabilizing effect on the system, and the stabilizing effect of harvesting dominates the stabilizing effect of refuge. Of most interest is the finding of coexisting attractors and multistability. In particular, optimal harvesting policy has been obtained by extension of Pontryagin's maximum principle to discrete system. Finally, some intriguing numerical simulations are provided to verify our analytic findings and rich dynamics of the three species system. [ABSTRACT FROM AUTHOR]

Creating accurate predictive models for drift and pack ice is crucial for a wide array of applications, from improving maritime operations to improving weather prediction and climate simulations. Traditional large‐scale sea ice dynamics models rely on phenomenological ice rheology to simulate ice movements. These models are efficient on large scales but struggle to depict smaller‐scale ice features. In our study, we use a new version of the HiDEM discrete element model software to examine the formation of drift and pack ice under various stress conditions. Our findings show that high‐resolution size distributions of ice floes are universal and multimodal, and that compression ridges form three distinct zones. Reproducing complex characteristics of this nature in a standard rheology model is challenging, suggesting that a combination of models may be necessary for more precise predictions of sea ice dynamics. We propose a potential hybrid algorithm that integrates these approaches. Plain Language Summary: Sea ice forms in cold climates and is susceptible to being easily fragmented by wind and currents, resulting in a dynamic landscape comprising solid fast ice, drift ice and pack ice. Pack ice, in particular, can pose challenges such as hindering shipping, causing damage to offshore structures, and complicating traditional fishing and hunting activities. Operational models for sea ice dynamics are currently utilized to optimize ship routes and the deployment of icebreakers. Although existing rheology‐based models perform well on large scales, they encounter difficulties in capturing the finer details that are often crucial. In this study, we utilize a high‐resolution Discrete Element Model computer code that is capable of simulating detailed sea ice dynamics at scales ranging from meters to kilometers. Our simulation results reveal insights that are not readily obtained from conventional large‐scale models, and we explore the potential for integrating these two approaches to create a hybrid model. Key Points: Ultra high‐definition simulation (0.5 m elements) of sea ice fragmentation on a square kilometer scaleThe HiDEM model captures in fine detail the formations of leads, pressure ridge networks, and floe‐size distributionsThe model reveals features that cannot be reproduced by rheological models, suggesting a hybrid method for prediction [ABSTRACT FROM AUTHOR]

In this work we base our analysis on a seminal paper by Paul Germain (1973) in which the principle of virtual work is used to found microstructured continuum mechanics. Recently, it was shown that a particular considered microstructured continuum can be regarded as a second gradient continuum of the kind studied by Germain. To prove how these theoretical ideas can be useful in applications, we present the paradigmatic case of pantographic metamaterials, in which the deformation energy may depend only on placement second gradient being independent on placement first gradient. In this case, the numerical simulations become more efficient by introducing the Lagrange multipliers which are dual in work of the introduced kinematical constraint, so proving that the viewpoint about stress presented originally by Lagrange is the most fruitful one. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusions Frequency‐of‐seeing (FoS) curves (psychometric functions) for perimetric stimuli have been widely used in computer simulations of new visual field test procedures. FoS curves for age‐related macular degeneration (AMD) are not available in the literature and are needed for the development of improved microperimetry test procedures, which are of particular interest for use as clinical trial endpoints.Data were refitted from a previous study to generate FoS curves for 20 participants with AMD, each tested at nine locations within the central 10°. Stimulus parameters, background luminance and dB scale were matched to the MAIA‐2 microperimeter, and stimuli were presented in a method of constant stimuli to build up FoS curves over multiple runs. FoS curves were fitted with a modified cumulative Gaussian function. The relationship between sensitivity and slope of fitted FoS curves was modelled by robust linear regression, producing models both with and without an eccentricity parameter.FoS curves were satisfactorily fitted to data from 174 visual field locations in 20 participants (age 65–83 years, 11 female). Each curve was made up of a median of 243 (range 177–297) stimulus presentations over a median of 12 (range 9–32) levels. Median sensitivity was 25.5 dB (range 3.8–31.4 dB). The median slope (SD of fitted function) was 1.6 dB (range 0.5–8.5 dB). As in previous studies of other conditions, the slope of fitted FoS curves increased as sensitivity decreased (p < 0.001).FoS are provided for participants with AMD, as well as models of the relationship between sensitivity and slope. These fitted models and data may be useful for computer simulation studies of microperimetry procedures. Full details of the fitted curves are provided as supporting information. [ABSTRACT FROM AUTHOR]

Herein, a thermofluid–solid coupling model with erosion structure is established based on a blast furnace (BF) with a volume of 5500 m3. The temperature distribution of the hearth and the thickness of the solidified iron layer are studied under five hearth protection measures. It is found that the thickness of the solidified iron layer can be increased by the reduction of the production rate, closing the tuyere, increasing the taphole length, tapping through two opposite tapholes, and increasing cooling intensity. In particular, the reduction of the production rate is the most effective way to increase the thickness of solidified iron layer. In the case of the two tapholes that are near the erosion area for tapping, the solidified iron layer is found to be the thinnest. The validity of the model is verified by the thermocouple temperature of the hearth at different periods. [ABSTRACT FROM AUTHOR]

In the Shaanxi‐Inner Mongolia region, where most mines employ wide coal pillar retention and dual entry layout techniques, mining pressure manifestations frequently occur during working face retreatment, posing significant challenges to safe and efficient coal production. Based on numerical simulation, theoretical analysis, and field test research, this study proposes a technical solution for preventing rockburst hazards in a wide coal pillar return airway. The research findings indicate the following: (a) Through numerical simulation and theoretical analysis, during the working face retreatment process, the wide coal pillar return airway exhibits a characteristic h‐pattern of high‐stress distribution, with asymmetric camelback curves appearing within the wide coal pillar, leading to significant static load concentration. When the roof breaks, the coal pillar bends excessively, and a large amount of energy is released, potentially causing instability. (b) Through the numerical simulation analysis, the stress peak value of the two sides of the return air lane of 21,103 working face decreases the most when the hole length is 15 m, the hole diameter is 150 mm and the hole distance is 1 m. (c) Implementation of drilling relief with a large diameter in the field effectively alleviates the issue of the return airway adjacent to the wide coal pillar, causing the stress peaks to shift deeper into the rock mass, this significantly reduces the risk of rockburst occurrence. [ABSTRACT FROM AUTHOR]

Temperature‐adaptive variable emissivity reflectors offer an electricity‐free and environmentally friendly cooling strategy, holding substantial potential to improve the global energy landscape. However, challenges associated with unoptimized solar absorptance can lead to overcooling or overheating when the modulation of infrared emittance is held constant, thereby increasing extra energy consumption. Herein, a temperature‐adaptive variable emissivity reflector based on W‐Mg co‐doped VO2 (W‐Mg‐VER) is proposed, engineered to optimize solar absorptance (αL = 0.40) while maintaining effective infrared emittance modulation (Δɛ = 0.69) near ambient temperature. To maximize year‐round energy savings in regions experiencing significant daily temperature fluctuations, W‐Mg co‐doped VO2 is employed to reduce solar absorptance by modifying electron occupancy in the V 3d orbital and expanding the optical bandgap. Outdoor experiments have validated the remarkable temperature management and energy‐saving capabilities of the W‐Mg‐VER, facilitated by its seamless transition between radiative cooling and heat‐retaining modes. Numerical simulation indicates that a W‐Mg‐VER roof covering 100 m2 would save 152.9 GJ of energy annually in locations with significant daily temperature variations. Moreover, W‐Mg‐VER demonstrates robust performance, exhibiting less than 1% degradation in emittance tunability and solar absorptance after 10 000 cycles. This approach provides valuable insights and practical guidance for significantly enhancing global energy savings. [ABSTRACT FROM AUTHOR]

Numerical modeling offers a valuable alternative to analytical solutions for pumping test analysis. However, little is known about how discretization impacts results accuracy and runtime. This study presents a systematic method for defining the spatiotemporal discretization of pumping test numerical models based on dimensionless parameters. Two types of analysis are considered: one where observations are made in the pumping well, and another one where observations are made in different wells. The influence of the discretization parameters on results accuracy and runtime is investigated and an optimal set of parameters is determined that minimizes runtime while maintaining the maximum error under 1% for an “average” aquifer. Lower runtimes are achieved when the analysis focuses on the pumping well, which is attributed to the steady‐state analytical solution approximating drawdown in the well in the numerical scheme employed. Additional tests demonstrate the robustness of the derived set of parameters in different configurations. [ABSTRACT FROM AUTHOR]

Highlights Dewetting is one of the most common damage modes in particulate filled polymer composite, which greatly damages the structural integrity of the composite and leads to the deterioration of its mechanical properties. Studying the dewetting evolution process of composite is of great significance for evaluating the meso damage degree of composite and suppressing the development of dewetting damage. This article constructs an axisymmetric cylindrical cell model of a single particle inclusion matrix, derives the interface dewetting evolution process of the model under uniaxial tensile loading condition, and analyzes the influence of model geometric parameters and external loading conditions on the dewetting process. Subsequently, numerical models were constructed at both micro and meso scales, and dynamic tensile calculations were performed to analyze the correlation between the dewetting rate, porosity, and mechanical performance. Finally, a cylindrical cell specimen was designed to observe the interface dewetting evolution under uniaxial tensile conditions, confirming the conclusions of theoretical analysis and numerical simulation. Constructed a theoretical model for the dewetting process of interface. Conducted numerical analysis of dewetting process at both meso and micro scales. Designed interface dewetting experiment and analyzed the dewetting process. [ABSTRACT FROM AUTHOR]

Summary: It is well known that hardware impairments (HWIs) can worthy reduce the wireless system performance at high carrier frequencies by showing random effects. Most current researches for 5 GB systems assume that transmitters and receivers (transceivers) are perfectly equipped. But wireless transceivers (TxRx) are affected by HWIs in practice. Considering the previous studies in the literature, it is reported that HWIs have devastating effects on the performance of OFDM and OFDM‐index modulation (IM) systems with fading channels. In this paper, in‐phase and quadrature phase imbalance (IQI), which is the one of most HWIs between transmitter and receiver in wireless communication systems, is examined on OFDM‐IM system over Rayleigh and Nakagami‐ m fading channels. Two well‐known detectors, the maximum likelihood (ML) detector and the log‐likelihood ratio (LLR) detector are used under the effect of the IQI at TxRx. Error performance analyzes over fading channels of the IQI effect on OFDM‐IM system are realized first theoretically and then by computer simulations. Results obtained for the presence of IQI at TxRx show that a performance evaluation based only on the presence of IQI in the receiver would be optimistic and misleading in terms of the performance of real‐life OFDM‐IM systems. [ABSTRACT FROM AUTHOR]

Summary: This paper addresses the problem of fixed‐time (F‐T) control for unmanned aerial vehicle (UAV) formation under unknown input disturbances to achieve moving target tracking. First, a kinematic model with uncertainties is employed to analyze the transient response of the UAV formation accurately. Next, based on a fast F‐T lemma, an F‐T disturbance observer is constructed to estimate the unknown disturbances. Subsequently, based on the designed observer and fast F‐T lemma, a distributed F‐T guidance law that controls multi‐UAV to track a moving target in a desired formation is introduced. Then, through rigorous mathematical proof, it is established that the control strategy enables the formation system to achieve F‐T stability, and the convergence time is independent of the system's initial states. Finally, the validity of the proposed control method is demonstrated through numerical simulation and presented in a realistic visual simulation scenario created using Unreal Engine 4 (UE4). [ABSTRACT FROM AUTHOR]

This article introduces the problem of predefined‐time attitude takeover control for spacecraft. A novel radial basis function neural network predefined‐time extended state observer is presented, which facilitates estimation of external disturbance, unmeasurable angular velocity, and actuator installation deviation within a predefined‐time. A quantizer is then employed to quantize control input signal in controller‐to‐actuator side to mitigate communication pressure. Thereafter, a novel predefined‐time attitude controller is proposed to ensure system states converge within a predefined‐time. Finally, the effectiveness of the proposed control scheme is substantiated via numerical simulation. [ABSTRACT FROM AUTHOR]

Summary: This paper addresses the issue of distributed finite‐time attitude coordination control of spacecraft formations with multiple constraints on angular velocities and control torques. First, the multiple constrained problem is transformed into a bounded issue by virtue of the nonlinear transformation technique and an input saturation model. Next, the nearest neighbor rule is applied to deal with the problem of the unavailability of the leader's information to all followers. Then, a distributed attitude coordination control algorithm is derived to enforce that all attitude tracking errors can converge to a neighborhood around the origin in finite time even when there exist multiple constraints and external disturbances imposed on spacecraft systems. Finally, several numerical simulation examples are presented to illustrate the efficiency of the derived method. [ABSTRACT FROM AUTHOR]

Helium (He) exerts significant influence on the physicochemical, structural, and electronic properties of pyrochlores. This paper reviews recent advancements in computer simulations aimed at stabilizing nuclear waste, focusing on disordered structures of pyrochlores, zirconate pyrochlores, and high‐entropy pyrochlores. Using Pu‐La2Zr2O7 as a case study, we demonstrate how a first‐principles approach facilitates the understanding of how He modifies the structural and electronic properties of this system. The incorporation of He interstitials in Pu‐La2Zr2O7 typically leads to an expansion in lattice constant and volume swelling. Analysis of the formation energies in this system reveals that octahedral interstitial sites or zirconium (Zr) vacancy sites are favored for He occupation, resulting in the formation of substitutional He atoms. The low concentration of He atoms in Pu‐La2Zr2O7 reduces the formation energy of cation antisite defects. Bader charge analysis indicates that the < Zr‐O > bond exerts a greater influence on the irradiation resistance of the He‐Pu‐La2Zr2O7 system compared to the < La‐O > bond. Moreover, the capacity for He interstitials increases with higher Pu concentration in the octahedrons. [ABSTRACT FROM AUTHOR]

ABSTRACT Evaluating the cathodic protection (CP) effectiveness of horizontal directional drilling (HDD) pipe is a significant technical challenge, due to the feasibility of testing only in shallow buried areas at entry/exit extremities, and not in deeply buried areas or the crossing section of the pipe. Numerical simulation provides a method to evaluate the CP effectiveness of HDD pipes. To improve the accuracy of potential distribution along the HDD pipe, it is necessary to adopt appropriate boundary conditions of the HDD pipe and accurate holiday models of coating. A specialized deep well polarization test device was designed and employed in the field to obtain the actual polarization characteristics as the boundary condition of the HDD pipe at buried depths ranging from 2 to 25 m. The result revealed that the polarization characteristics of HDD pipe in various depths were different and the potential distribution of the actual situation was greatly different from the potential distribution of the shallow aerobic soil. The potential distribution along the HDD pipe was analyzed in two types of holiday models. The results could be used as a reference for the CP effectiveness evaluation of HDD pipes. [ABSTRACT FROM AUTHOR]

Previous models of circular ring segment joints have been inadequate in describing their loading capacity due to the lack of consideration for the interaction between shear force and bending moment. Consequently, these models have led to over‐ or underestimation of the joints' capacity. The increasing use of dry joint connection technology in wind turbine towers and prefabricated segmental bridge constructions necessitates the development of advanced computational models for these connections. This study presents a new model that considers the effects of bending moment, shear force, and torsion on the loading capacity of circular ring segment joints. Numerical simulations were conducted to validate the developed model under different load combinations, and the results demonstrate excellent agreement between the model predictions and numerical simulations. [ABSTRACT FROM AUTHOR]

This article presents a study of interval estimation approach based on functional interval observers for mecanum‐wheels omnidirectional automated guided vehicle (MOAGV). In the context of MOAGV, the nonlinear system in discrete time incorporates model uncertainty and unknown bounded disturbances. A functional observer is developed by integrating terminal sliding mode and H∞$$ {H}_{\infty } $$ techniques, aiming to reduce the impact of lumped disturbances/uncertainties. Additionally, a novel observer structure is introduced to increase the degrees of freedom in the design process. Subsequently, the linear function bounds are obtained using the reachability analysis of the estimation error. Finally, the performance of the improved functional interval observer is demonstrated by numerical simulations. [ABSTRACT FROM AUTHOR]

Space‐time coding metasurfaces (STCMs) have gained a great deal of achievements in the fields of radar and communication, but they have rarely been explored in the field of electronic jamming. The existing researches use time‐varying surface or phase‐switched screens to realize electronic deceptions, but the deceptions are completely passive and are limited in the time‐frequency domain. Here, a mechanism of STCM‐based deceptions is presented in the space and the time‐frequency domains, and precise designs of the STCM‐based deceptions are achieved by performing shifting operations on the space‐time coding sequences of the STCM. Moreover, STCM‐based DOA (direction‐of‐arrival) estimation is integrated with the deception procedure to achieve trackable electronic deception which cannot be realized by completely passive electronic jamming. A prototype system of the STCM‐based deception is built to verify the deception performance, and the experimental results agree well with the numerical simulations. This work extends the research and the applications of the STCMs, hence showing great scientific and engineering significance. [ABSTRACT FROM AUTHOR]

Machine learning (ML) algorithms have become invaluable tools for tackling design challenges associated with achieving unique scattering effects in artificial electromagnetic materials (AEMs). However, their effectiveness is reliant on substantial, well‐constructed training datasets. Building such datasets using traditional methods becomes impractical for increasingly complex and large‐scale geometric models. Achieving a specific diffuse scattering is one example and this often requires electrically large and diverse AEM arrays. Unfortunately, while numerical simulations offer high accuracy by utilizing fine meshing, their computational limitations render them incapable of handling such large structures and computing their scattering parameters efficiently. This work proposes a new approach to overcome these limitations by replacing conventional numerical simulations with a hybrid method that combines electromagnetic simulations with an analytical model, enabling the rapid and accurate generation of datasets for electrically large metamaterial arrays. Utilizing this approach, an optimized metasurface geometry for the mid‐infrared range is successfully identified and tested that exhibits desirable diffuse scattering effects. This innovative method paves the way for significantly faster design and optimization of metamaterials, while also unlocking the potential for a new generation of large‐scale, high‐quality ML datasets for AEM problems. [ABSTRACT FROM AUTHOR]

The Schrödinger equation depends on the physical circumstance, which describes the state function of a quantum‐mechanical system and gives a characterization of a system evolving with time. The essential focus of proposed research is to observe the solution for fractional generalized nonlinear Schrödinger (FGNS) equation using q‐homotopy analysis transform method (q‐HATM). The fractional order derivative is taken in the Atangana‐Baleanu (AB) sense. The physical behaviours of achieved solution for FGNS equation are discussed and sketch out graphically. The existence of the solution for the FGNS equation is presented through theorems 4.1 to 4.3. The proposed numerical simulations confirm the advantages of the AB derivative through q‐HATM. Few numerical experiments were carried out to validate the proposed method. Moreover, numerical simulations are carried out to verify efficiency and robustness of the derived results by considering two cases. [ABSTRACT FROM AUTHOR]

We present an efficient approach to quantify the uncertainties associated with the numerical simulations of the laser‐based powder bed fusion of metals processes. Our study focuses on a thermomechanical model of an Inconel 625 cantilever beam, based on the AMBench2018‐01 benchmark proposed by the National Institute of Standards and Technology (NIST). The proposed approach consists of a forward uncertainty quantification analysis of the residual strains of the cantilever beam given the uncertainty in some of the parameters of the numerical simulation, namely the powder convection coefficient and the activation temperature. The uncertainty on such parameters is modelled by a data‐informed probability density function obtained by a Bayesian inversion procedure, based on the displacement experimental data provided by NIST. To overcome the computational challenges of both the Bayesian inversion and the forward uncertainty quantification analysis we employ a multi‐fidelity surrogate modelling technique, specifically the multi‐index stochastic collocation method. The proposed approach allows us to achieve a 33% reduction in the uncertainties on the prediction of residual strains compared with what we would get basing the forward UQ analysis on a‐priori ranges for the uncertain parameters, and in particular the mode of the probability density function of such quantities (i.e., its "most likely value", roughly speaking) results to be in good agreement with the experimental data provided by NIST, even though only displacement data were used for the Bayesian inversion procedure. [ABSTRACT FROM AUTHOR]

In this article, we propose a model‐free self‐triggered control approach for linear systems using a hierarchical policy framework. This framework splits the self‐triggered control approach into top and bottom‐level policies. The top‐level policy generates a triggering time interval based on an initial control strategy, while the bottom‐level policy creates a control inputs guided by the top‐level sub‐goal. This division ensures that both strategies have their own independent tasks and optimization goals, facilitating a model‐free iterative design process for self‐triggered control. The present structure integrates with a dual‐Actor Critic algorithm, utilizing two interconnected neural networks to approximate control and trigger policies. It reflects the framework of hierarchical reinforcement learning, wherein top‐level policies guide bottom‐level decision‐making. It fosters the model‐free design of self‐triggered controller, thereby enhancing the efficiency of the learning process. To validate the effectiveness of our proposed method, we conduct a series of numerical simulations. [ABSTRACT FROM AUTHOR]

In this article, anti‐unwinding sliding mode attitude maneuver control with predefined time is investigated for rigid spacecraft with input saturation. First, a nonsingular sliding function containing two equilibrium points is designed to ensure the predefined‐time convergence of system states and unwinding‐free performance of the closed‐loop system on the sliding phase. Then, an auxiliary system with a dynamic parameter is presented to compensate the impact of input saturation. With this parameter, the auxiliary system can handle input saturation that occurs. Based on the sliding function and the auxiliary system, an attitude maneuver controller is developed to guarantee the robustness of the closed‐loop system to bounded external disturbance. Under the designed controller, the states of the closed‐loop system are driven into a neighborhood of the sliding surface within a predefined time. Moreover, the unwinding phenomenon is also avoided on the reaching phase. Numerical simulation results illustrate the unwinding‐free performance and predefined‐time convergence of the closed‐loop system under the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of actuator and sensor faults causing instability in leaderless/follower multi‐agent systems (MASs) and investigates adaptive fault‐tolerant control (FTC) algorithms to secure stability. Sensor faults can disrupt conventional observers by interfering with system state measurements. To address this issue, the descriptor approach is introduced to construct an augmented system from the original system, which converts the faults into components of the augmented system state. Next, by utilizing a sliding‐mode term to compensate for the lumped uncertainty's impact, an observer is designed to realize state estimation for the augmented system. Then, based on the estimations, adaptive FTC protocols are investigated for leaderless/leader‐follower MASs to retain stability against concurrent faults and uncertainties. To enhance control efficiency, the control gains are updated with the estimations from neighbors and proved to be ultimately upper bounded. Finally, the proposed method is validated through numerical simulations of multiple quadrotors. [ABSTRACT FROM AUTHOR]

Highlights This work aims to study the effects of bionic spiral stacking sequence, impact energy and impactor shape on the impact resistance of laminates. The finite element model is established based on the stress failure criterion, progressive damage evolution, and the triangle traction‐separation law. The reliability of the finite element model is validated through rigorous comparison with experimental data. The study investigates the influence of laminate layup sequence, impact energy, and impactor shape on the impact resistance of laminates. The results show that during low‐speed impacts, laminate damage is primarily characterized by fiber breakage, matrix cracking, and delamination. Matrix cracking and delamination become more pronounced as the impact energy increases. The design of linear spiral ply and power function spiral ply has a positive effect on the impact resistance of laminates. The impact resistance of laminates is sensitive to the sharpness of the impactor and the level of impact energy. Higher impact energy and sharper impactor shapes lead to increased energy absorption in the laminate, resulting in more pronounced damage failure. The impact resistance of bionic spiral composite laminates is studied. Three biologically inspired stacking sequences were designed. A numerical simulation method is proposed and verified. The low‐velocity impact characteristics of bionic laminates are revealed. [ABSTRACT FROM AUTHOR]

The stability and bifurcations of a fractional‐order neural network with a neutral delay are nicely contemplated with the help of the Cramer's rule. The three‐neuron neutral‐type fractional‐order neural network (NTFONN) is firstly constructed. Secondly, the Laplace transform of the Caputo fractional‐order derivatives is used. Afterward, using the analytical method of characteristic equations and Cramer's rule, the existence of Hopf bifurcations is obtained. Moreover, it indicates that the neutral delay plays an enormously significant role in remaining network stabilization and controlling the occurrence of Hopf bifurcations in NTFONN. It further detects that the devised NTFONN has outstanding stability performance in comparison with the corresponding integer‐order one. Finally, numerical simulations are developed to confirm the feasibility and validity of the obtained results. [ABSTRACT FROM AUTHOR]

This article aims to achieve scalable exact output and regulated output synchronization for discrete‐time multi‐agent systems in presence of disturbances and measurement noise with known frequencies. Both homogeneous and heterogeneous multi‐agent systems are considered, with parts of agents' states accessible in the latter case. The key contribution of this article is to establish scalable exact synchronization results under disturbances and measurement noise, which is achieved by using distributed protocols that only use information about agent models and no information about the communication network or the number of agents. The validity of the protocol is verified by numerical simulations with arbitrarily chosen number of agents. [ABSTRACT FROM AUTHOR]

It is commonly assumed that images, whether in the world or in the head, do not have a privileged analysis into constituent parts. They are thought to lack the sort of syntactic structure necessary for representing complex contents and entering into sophisticated patterns of inference. I reject this assumption. "Image grammars" are models in computer vision that articulate systematic principles governing the form and content of images. These models are empirically credible and can be construed as literal grammars for images. Images can have rich syntactic structure, though of a markedly different form than sentences in language. [ABSTRACT FROM AUTHOR]

A reverse calculation method termed soil and lining physics‐informed neural network (SL‐PINN) is proposed for the estimation of load for tunnel lining in elastic soil based on radial displacement measurements of the tunnel lining. To achieve efficient and accurate calculations, the framework of SL‐PINN is specially designed to consider the respective displacement characteristics of surrounding soil and tunnel lining. A multistep training method based on the meshless characteristics of SL‐PINN is established to promote calculation efficiency. The multistep training method involves increasing the number of collocation points in each calculation step while decreasing the learning rate after scaling of SL‐PINN. The feasibility of SL‐PINN is verified by numerical simulation data and field data. Compared to other inverse calculation methods, SL‐PINN has lower precision requirements for the measurement instrument with the same level of calculation accuracy. [ABSTRACT FROM AUTHOR]

Serum creatinine in neonates follows complex dynamics due to maturation processes, most pronounced in the first few weeks of life. The development of a mechanism‐based model describing complex dynamics requires high expertise in pharmacometric (PMX) modeling and substantial model development time. A recently published machine learning (ML) approach of low‐dimensional neural ordinary differential equations (NODEs) is capable of modeling such data from newborns automatically. However, this efficient data‐driven approach in itself does not result in a clinically interpretable model. In this work, an approach to deriving an interpretable model with reasonable PMX‐type functions is presented. This "translation" was applied to derive a PMX model for serum creatinine in neonates considering maturation processes and covariates. The developed model was compared to a previously published mechanism‐based PMX model whereas both models had similar mechanistic structures. The developed model was then utilized to simulate serum creatinine concentrations in the first few weeks of life considering different covariate values for gestational age and birth weight. The reference serum creatinine values derived from these simulations are consistent with observed serum creatinine values and previously published reference values. Thus, the presented NODE‐based ML approach to model complex serum creatinine dynamics in newborns and derive interpretable, mathematical‐statistical components similar to those in a conventional PMX model demonstrates a novel, viable approach to facilitate the modeling of complex dynamics in clinical settings and pediatric drug development. [ABSTRACT FROM AUTHOR]

Microchannel geometry is an important factor in determining droplet dynamics in droplet‐based microfluidic systems, much like fluid properties and flow conditions. In this context, two important geometric parameters—the contraction ratio (CII ${C}_{{II}}$) and the width ratio (CI ${C}_{I}$)—that are limited to particular value ranges are taken into consideration for evaluation. These parameters interact with the capillary number (Ca ${Ca}$) and viscosity ratio (λ $\lambda $) to affect different aspects of droplet migration and manipulation, such as trap and squeeze regimes. A theoretical model is proposed, and a three‐dimensional numerical simulation method is used in this work. This model predicts the change from trap to squeeze, which is caused by the interaction of the previously mentioned variables. Interestingly, an inverse correlation exists between the width ratio and the critical capillary number for this transition, which is determined as Ca≥f(λ,CII)/CI ${Ca}\ge f(\lambda ,{C}_{{II}})/{C}_{I}$. Furthermore, the investigation explores the droplet elongation and velocity ratio during their passage through the microchannel. By matching input parameters with microchannel geometry, this information may be useful for the design of microfluidic systems, which would facilitate the careful control and manipulation of droplets. [ABSTRACT FROM AUTHOR]

A 3D model is established to discuss the influence of combustion reaction on jet characteristics. Based on this, combustion behaviors of supersonic jet for single‐flow postcombustion oxygen lance with various secondary nozzle parameters (diameter, inclination angle, and number) are analyzed. The results indicate that after activating combustion reaction, the jet velocity, dynamic pressure, density, and temperature of primary jet at H = 1.45 m are 1.27, 1.15, 0.56, and 1.97 times than those of without considering the combustion, respectively. Enlarging secondary nozzle diameter is helpful to extend the flame core lengths of primary and secondary jets (the axial distance from lance tip to isotherm of 1773 K) as well as the combustion region. With the increase of secondary nozzle angle, the two flame core lengths both decrease, while the combustion zone increases. Increasing the number of secondary nozzles, the flame core length of primary jet increases while that of the secondary jet decreases, and the combustion region first increases and then decreases. As for the influences of the above parameters on flame core lengths of primary and secondary jets as well as the combustion region, the number is the greatest, followed by the inner diameter, and the inclination angle is the smallest. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) structures are mainly designed to withstand both static and dynamic loads. However, due to the highly nonlinear behavior of RC structures subjected to extreme dynamic loads, these structures have a very complex damage behavior under dynamic impact loading. In fact, current existing methods for damage‐simulation and prediction are generally based on either empirical data, simplified mechanical approaches or complex numerical simulations mainly using the finite element method. In this regard, empirical and semi‐empirical models can be considered to calculate the load‐bearing capacity in a simplified way with only a few input parameters. Hence, using current experimental test data, this paper aims to analyze and assess existing empirical and semi‐analytical approaches that are established in standards and guidelines. Accordingly, a functional relationship in terms of an impact factor is found. Based on the obtained results, different approaches are also developed to describe the resistance to projectile penetration of RC structures as well as the force interaction between projectile and RC structures. [ABSTRACT FROM AUTHOR]

Laboratory experiments and numerical simulations were performed to explore the influence of intersection geometry on fluid flow and solute transport in fractures. Fractures were engraved and sealed into an acrylic plate and two orthogonal intersections with different geometry were constructed. The effects of curvature and relative shear displacement at intersections on preferential flow and solute transport were investigated. By solving the Navier–Stokes (NS) equation, the fluid mixing and solute distribution were predicted. The results showed that the geometric characteristics at the intersection have a significant effect on the preferential flow and solute distribution. The results agreed well with the experimental results, in terms of flow direction, preferential flow rate, and heterogeneous solute distribution. With an increase in curvature, the flow difference between the two outlets increases gradually. Increasing curvature can reduce the preferential flow and weaken the inhomogeneity of solute distribution. An increase of relative shear displacement decreases the pressure gradient and flow rate at the entrance of the two branch fractures, and thereby increases preferential flow and inhomogeneity of solute distribution. The results provide a basis and reference for further exploring the relationship between the geometric characteristics of fracture intersections and flow behaviors. [ABSTRACT FROM AUTHOR]

Human visual memory capacity has a rapid developmental progression. Here we examine whether image semantics modulate this progression. We assessed the performance of children (6–14 years) and young adults (19–36 years) on a visual memory task using real‐world (or meaningful) as well as abstract image sets, which were matched in low‐level image attributes. For real images, we find comparable performance across the two age groups, consistent with previously reported results. However, for abstract images, we find a clear age‐related difference indicating greater reliance of children's memory processes on semantics, suggesting that strategies for encoding abstract patterns keep improving even into late childhood. We complemented these studies with computational experiments designed to examine the role of increasing experience with real‐world images on real and abstract image encoding, to examine whether the observed age‐related differences, as well as the general privilege of real over abstract images, can emerge directly through experience with meaningful images. Our results provide support for this possibility and set the stage for a finer‐grained investigation of the timeline along which children's memory capacity for abstract images reaches adult levels. [ABSTRACT FROM AUTHOR]