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

• Numerically investigate folding pattern and rigid-flexible coupled dynamics of satellite-sphere system. • Achieve a larger volume folding rate by pattern of inflatable sphere with orderly deployment. • Inflating process has great influence on satellite based on rigid-flexible coupled dynamic model. • Reduce influence by heavier satellite, small inflation rate and appropriate control torque. Inflatable spheres can be applied to the aerodynamic drag deorbiting device for satellites. It may bring about a complicated dynamic problem under the disturbance from the lightweight large-volume inflatable sphere to the satellite. In order to explore this problem, rigid-flexible coupled dynamics behaviors of satellite-sphere system during inflating process are numerically studied in this paper. The folding pattern of inflatable sphere is designed to obtain the parametric model in the folded state. The dynamic analysis model of this system is established to analyze dynamic behaviors, including the dynamics of the satellite-sphere system, the gas state of the airbag and the disturbance to the satellite, during the inflating process. Parameter effects on the attitude disturbance are studied. The results show that the satellite mass, inflating mass rate and control torque have a great impact on the attitude disturbance. These works provide theoretical bases and technical supports for the engineering development of inflatable sphere deorbiting devices. [ABSTRACT FROM AUTHOR]

On-orbit capturing is a crucial step in the application of dual-arm space robots, aiming to accurately grasp a moving target and avoid damage to the arms terminal parts (i.e. the end effectors) due to contact force saturation. This paper presents a synthetic control method with target sticking for on-orbit capturing using a dual-arm space robot system from the approaching phase to pre-grasping phase. In the approaching phase, an online trajectory planning method based on visual servoing is proposed to obtain the desired trajectories for end effectors in work space. Then the joint torques are designed by the inverse kinematics and inverse dynamics to track the desired trajectories. Different from most of the current research, a new sticking phase is proposed after the approaching phase and before the pre-grasping phase. In the sticking phase, a force and motion control method is designed to maintain a close relative distance between end effectors and the target, which can avoid saturation of contact forces and avoid damage to the end effectors. In what follows, an impedance control method is proposed in the pre-grasping phase to absorb the impact energy and grasp the target accurately. The synthetic control strategy integrates the controllers of all the phases mentioned above. Automatic switching among the phases is realized by using logic judgment according to the system real states, which is more consistent with the real capturing environment. Finally, numerical simulation results demonstrate the effectiveness of the proposed synthetic control scheme. The results can be applied to the trajectory planning and control of on-orbit capturing, avoiding contact force saturation and ensuring the safety of the system. [ABSTRACT FROM AUTHOR]

Advancements in bulk metallic glass thermoplastic forming unleash the potential to fabricate microscale metallic features with unparalleled precision and durability, i.e. microspine gripping structures for mobility platforms on planetary or in-space robots. Four designs of grippers were fabricated and rigorously tested. Coefficient of friction on four test surfaces were measured and compared to SiC paper and Velcro. The hardness and elasticity of the bulk metallic glasses make them a game-changer in the field, offering a superior alternative to conventional nonmetallic grippers. • Microspine grippers were manufactured via thermoplastic forming of bulk metallic glasses using silicon-on-insulator molds. • The microspines excelled on textured surfaces, where sharp points anchor on to pores or softer regions. • Mechanical behavior of microspines were studied using nanoindentor-based micro-compression and computer simulations. [ABSTRACT FROM AUTHOR]

This paper proposes a method to describe the bi-modular behavior of quasi-brittle materials. The approach is based on using multiple loading functions that are associated with the stress state of the material point. The model also includes degradation laws that control the evolution of the internal variables under tension and compression, which allows the representation of the material response with fidelity. The following approach outlines an objective methodology for improving classical models and provides a theoretical framework for developing new constitutive models. This work also presents an updated version of the Mazars damage model, with improved material parametrization through multiple damage laws. Similarly, the modified von Mises model has been extended to include different functions for damage evolution, combining exponential and continuum polynomial laws for tension and compression. A third model was developed to showcase the full potential of the proposed formulation. This model formulates the Lemaitre and Chaboche criterion, typically used for ductile materials, to describe quasi-brittle materials. The model provides a comprehensive characterization of the tension and compression behavior by utilizing various loading functions and multiple damage laws. Numerical simulations of experimental benchmarks are presented to show the performance of the proposal, including a nonlocal approach to avoid strain localization and mesh dependency problems. • A formulation to represent simply the bi-modularity of quasi-brittle materials by isotropic damage models is presented. • The proposal provides versatility to prescribe any damage law, especially with fill constitutive parameters. • The strategy is applied to classical models present in literature providing an enhancement of the model behavior. • The approach can be extended and applied to other models presented in the literature. [ABSTRACT FROM AUTHOR]

• An optimal nutation reduction method based on a flexible contactor is proposed. • A highly efficient data-driven model is established to describe the contact process. • The nutation of a tumbling satellite can be reduced efficiently in the early stage of the de-tumbling tasks. Stabilizing tumbling satellites is a crucial step in ensuring safe on-orbit capture. A new de-tumbling method has been proposed that uses a flexible device, such as a brush or rod, to make contact with the target object and avoid potential collisions. However, this method faces two challenges: (i) The complex rotary motion makes it very difficult to determine the contact position on the target satellite, which is crucial to reduce nutation during de-tumbling. (ii) The conventional finite-element-based dynamic model of the flexible contactor is high-dimensional, leading to unacceptable computing time for on-orbit simulation. To address these problems, this paper proposes an optimal method to efficiently reduce the nutation by predicting the initial contact position for each contact process. Additionally, a fast computation model of the de-tumbling system is established based on a data-driven approach to support real-time prediction. Finally, numerical simulations are conducted to demonstrate the effectiveness and high efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

• A method of uncertainty analysis based on the MP-II model was proposed to examine a case of adhesive assembly. • Uncertainty transfer was constructed by a combination of finite-element simulation and a B-spline surrogate model. • The effect of the uncertainties of three types of bonding defects on the center-of-mass drift was understood. • The reliability index was improved and the parameter intervals of the bonding defects were optimized. Multi-source and strong uncertainties of the adhesive assembly process for high-precision inertial devices are critical issues that result in the current low assembly accuracy and poor assembly consistency. This paper addresses the resulting uncertainty in the center-of-mass drift of the float components of a high-precision inertial device. An interval-based non-probabilistic convex model is used to characterize the uncertainty of the bonding defect parameters of the adhesive assembly process, and the uncertainty transferring from those parameters to the center-of-mass drift is constructed by using a surrogate model and numerical simulations. A reliability analysis is carried out to understand the effect of the uncertainties of three types of bonding defects on the center-of-mass drift, and the sensitivities of the center-of-mass drift to the bonding defects are also found. The results show that the reliability index of the center-of-mass drift obtained under the initial parameter intervals is 0.689, indicating the center-of-mass drift at the risk of being out of the accuracy requirement. By adjusting the parameter intervals of the bonding defects to stabilize the center-of-mass of the assembled components, the reliability index is then improved to greater than 1. [ABSTRACT FROM AUTHOR]

This paper mainly studies the high-order stable numerical solutions of the time-space fractional diffusion equation. The Fourier spectral method is used for discretization in space and the Spectral Deferred Correction (SDC) method is used for numerical solutions in time. Therefore, a high-precision numerical discretization scheme for solving the fractional diffusion equation is obtained, and the convergence and stability of the scheme are proved. Finally, several numerical examples are given to illustrate the effectiveness and feasibility of the numerical scheme. [ABSTRACT FROM AUTHOR]

• The modified phase-field approach and the arbitrary Lagrangian–Eulerian one are able to give physically and quantitatively correct results for modeling electrocoalescence • The exponential relation between volume fraction and electrical conductivity has to be used in the phase-field approach when the conductivity of two phases differs significantly • The power of the volume fraction under the exponent has to be adjusted to centralize the space charge within the interface layer • The phase-field model needs for proper choice of the mobility turning parameter and the interface thickness and has a limited applicability for computing long-term processes • The arbitrary Lagrangian–Eulerian approach is more precise and less resource-intensive than the phase-field one The paper examines two numerical approaches to the simulation of electrical deformation and coalescence processes in water-in-oil emulsions: the phase-field method and the arbitrary Lagrangian–Eulerian approach. The former employs a diffuse interface, while the latter utilizes a sharp interface. The study analyzes the correctness of the computer simulation results and identifies less obvious limits of the applicability of these numerical techniques. The paper is based on a step-by-step comparison of data from two independent numerical models and quantitative verification using original experimental data, including data on unsteady-state droplet deformation and the threshold between coalescence and non-coalescence. The main findings are as follows. Both methods, the modified phase-field approach and the arbitrary Lagrangian–Eulerian one, are fundamentally capable of providing physically and quantitatively correct results for modeling electrohydrodynamic processes in two-phase immiscible liquids. On the one hand, the phase-field method demands thorough tuning and has limited applicability for simulating long-term processes. On the other hand, the arbitrary Lagrangian–Eulerian approach offers greater precision and requires fewer computational resources compared to the phase-field method, although it demands a manual adjustment of geometry when the system's topology changes. It is noteworthy that the phase-field method, without careful tuning, fails to yield quantitatively accurate results; errors, such as discrepancies in the time convergence of droplets under the influence of an electric field, can reach magnitudes of tens of percentages. [Display omitted] [ABSTRACT FROM AUTHOR]

• A comprehensive review on numerical simulations of boiling heat transfer from atomistic to mesoscopic and macroscopic scales is presented. • Critical issues related to nanoscale bubble nucleation mechanisms, pool boiling, and flow boiling are highlighted. • Potential solutions and future research in the field of boiling heat transfer using the MDS, LB and CFD methods are proposed. Boiling is an efficient heat transfer mode with significant potential for thermal management in high-power electronic equipment. However, a comprehensive understanding of the boiling process, which encompasses bubble nucleation, growth, coalescence, slipping, and detachment across various scales, remains challenging. Molecular dynamics simulation, lattice Boltzmann, and computational fluid dynamics methods are popular and powerful tools for investigating boiling heat transfer phenomena at microscopic, mesoscopic, and macroscopic scales. These methods enable researchers to uncover the underlying boiling mechanisms and propose heat transfer enhancement techniques. Therefore, this paper provides a comprehensive review of boiling heat transfer, spanning from atomistic to mesoscopic and macroscopic scales, utilizing these three numerical methods. It addresses critical issues related to nanoscale bubble nucleation mechanisms, pool boiling, and flow boiling, and proposes potential solutions and future researches, supplementing our previous review [Some advances in numerical simulations of multiscale heat transfer problems and particularly for boiling heat transfer, Annu. Rev. Heat Transf., 6 (2022) 217–269]. Besides, by shedding light on the characteristics of these numerical methods in studying boiling heat transfer, this paper aims to foster their development and advance enhanced heat transfer technologies. [ABSTRACT FROM AUTHOR]

• A mechanics–thermotics–chemistry coupling response model for energetic materials was developed based on the MPM3D. • The continuous expansion and thickening of jet due to high-temperature and high-pressure products leads to the decrease of penetration depth and the increase of crater diameter. • The simulation results of reactive materials jet against steel targets agree well with the experimental results. With its unique kinetic penetration/chemical implosion combined damage ability, reactive damage element (RDE) can greatly or even leap the damage power of ammunition warhead, and has a promising application prospect in the field of ammunition. However, due to the high transient and nonlinear characteristics of shock release process, there is still a lack of real-time quantitative research methods to investigate its energy release process under impact loads, which makes it difficult to conduct in-depth analysis of its efficient damage mechanism. In this paper, the Grüneissen equation of state in the P-V-T form is derived to solve the problem of the mechanics–thermotics–chemistry coupling response (MTCCR) of reactive materials (RMS) under impact load, and the calculation model of RMS temperature under impact is established. Based on the pressure equilibrium criterion, a two-phase theoretical model of the reaction flow field between the RMS reactant and the reaction product was proposed. Combined with the impact temperature rise theory, heat conduction theory and the Arrhenius chemical reaction kinetic model, the MTCCR model of RMS was established. The method of material point-impact induced chemical reaction (MPM-SICR) is presented and the energy release behavior of RMS is quantitatively researched in real-time. This method is used to numerically simulate the formation and impact induced energy release behavior of reactive materials jet against steel target. The simulation results are in good agreement with the experimental results, indicating that the model and method proposed in this paper can well characterize the dynamic MTCCR behavior of the RDE under the impact. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive Virtual Reality (VR) based framework for visualizing numerical simulations of geophysical flows in a realistic and immersive manner. The framework allows integrating output data from various mesh-based Eulerian numerical models into a VR environment, enabling users to interact with and explore the terrain and geophysical flows through the VR experience. Three case studies, including a snow avalanche, quick clay landslide, and flash flood in Norway, demonstrate its versatility. The VR environment offers intuitive menus and user interactions, allowing users to read flow depth and velocity values, facilitating a direct link between numerical data and their visual representation. This framework can reshape geophysical flow hazard identification and disaster management by integrating physics-based numerical modeling results into VR Environments, thus enhancing knowledge dissemination among experts, the general public, non-expert stakeholders, and policymakers. The paper also highlights challenges and opportunities identified during the integration, guiding future developments. • A framework that integrates numerical simulations of geophysical flows into VR. • The framework is versatile across different geophysical flow types and numerical models. • Real time visualization of numerical simulation results is still a challenge. • The framework has a potential for disaster preparedness and emergency training. [ABSTRACT FROM AUTHOR]

• A novel discontinuous similar material for physical model experiments has been developed. • The bulking characteristics of the broken goaf roof under different roof cutting conditions have been revealed. • The protection effect of the roof cutting technology for the gob-side roadway has been obtained. • The excavation compensation effect of the bulking roof rock after failure by roof cutting has been proposed. The stability control of gob-side entry retaining (GSER) has consistently been an important topic of interest within the field of no-pillar mining. This paper presents a novel discontinuous similar material for conducting physical model experiments, in conjunction with discrete element numerical simulation, to investigate the goaf roof failure and bulking characteristics based on gob-side entry retaining by roof cutting. The results indicate that the application of roof cutting technology (RCT) can significantly expand the failure range of the goaf roof vicinity to the roof cutting line. This expansion leads to a 20% increase in the volume of broken roof rock, which in turn facilitates the formation of effective support and stress compensation for the overlying strata, and the possibility of failure and displacement in the overlying strata is reduced. RCT can decrease the length of the cantilever beam located on the gob-side roadway, which is beneficial for maintaining the stability of the roadway. This paper presents a rational approach for determining an appropriate roof cutting height and angle. The in-situ application results show that the deformation of the surrounding rock of GSER by RCT is small, indicating a high level of integrity, fully meeting the requirements of serving the production of the subsequent working face. This paper serves as a reference for future research on the stability control of gob-side roadways based on GSER approach. [ABSTRACT FROM AUTHOR]

This paper examines a Distributed Propulsion (DP) concept and involves CFD verification, optimisation and evaluation. The first part of the study validates the employed simulation methods using experimental data from the NASA Workshop for Integrated Propeller Prediction (WIPP) and the Folding Conformal High Lift Propeller (HLP) project, for isolated and installed cases under various conditions. Additionally, validation for rotor-rotor interactions was also conducted using the GARTEUR Action Group 26 measurements. The second part of the paper examines installed propeller configurations to identify performance differences based on their position relative to a lifting wing. The results indicate that distributed propellers with small radii interfere more with the wing, than tip-mounted, large propellers. Additionally, propeller and wing performance vary with respect to the propeller installation location. The propeller in tractor configuration showed higher efficiency than the over-the-wing (OTW) configuration by about 7%. However, results from this work showed a 2% improvement in the propeller efficiency when the OTW configuration had a pylon installed. This study also found that optimising the propeller from a tractor to OTW configuration, significantly improved the wing performance. At take-off and landing, the Lift-to-Drag (L/D) ratio of the OTW configuration almost quadrupled, and the overall propulsive efficiency increased by about 5%. The simulations showed that the OTW configuration with different numbers of propellers, outperformed the tractor configurations with the same number of propellers. Furthermore, up to 26% improvement in lift and overall propulsive efficiency was found by introducing the DP system in the OTW configuration. [ABSTRACT FROM AUTHOR]

• Vortex-inducing T-jet reactors greatly improve mixing performance. • Mixing effect can be significantly improved by vortex merging. • The change of inlet structure has an important effect on reactor performance. • The generation of unsteady symmetric flow was avoided by the vortex-inducing. Improving the jet reactor's mixing performance is critical and challenging. In this paper, a new type of vortex-inducing T-jet reactor proposed by researchers is studied. By designing the staggered inlet structure of the T-jet reactor, the vortex is induced in the flow field in the mixing channel to improve the mixing effect. Flow regimes and mixing characteristics in the vortex-inducing T-jet reactor were investigated through numerical simulations (CFD) at 30 ≤ Re ≤ 600. Results show that the staggered inlet channel induces vortices successfully, and the engulfment flow regime occurs at lower Reynolds numbers, thus promoting the mixing. The generation and evolution of vortex structures in the reactor were focused on. It was found that in the unsteady engulfment flow, the two fluids cross each other, which makes the vortex structure constantly twist and merge, which greatly improves the mixing effect. At larger Reynolds numbers, many attached small vortices are generated around the central vortex structure, and these vortices are wound together with the high-speed rotation of the central vortex, avoiding the unsteady symmetric flow pattern with a poor mixing effect. Finally, it is found that the mixing performance of the vortex-inducing T-jet reactor is greatly improved under all regimes. [Display omitted] [ABSTRACT FROM AUTHOR]

What are the geometrical and mechanical properties ruling bistability of Kresling origami metamaterials? How can we tune the magnitude of their axial-torsional coupling? Complete answers to these compelling questions cannot be found in the scientific literature, as the intertwining between bistability, axial-torsional coupling and an other significant behaviour, namely transverse dilation/contraction, remains mostly uninvestigated. This contribution aims at shedding light on this intertwining, through the use of a discrete model of Kresling origami that takes into account folding resistance. The present study is mostly computational and involves both pre- and post-critical analyses. It is based on displacement controlled tests — shearing and axial shortening/lengthening. Single-storey Kresling origami's are first considered, preliminarly to multiple-storey tubes, where buckling is observed. Several parameters are taken into account such as the number of storeys, stretching and folding stiffnesses, and – for shearing tests – the prescribed displacement direction in the transversal plane. The ultimate goal of the paper is to provide evidence that can be useful in the construction of homogenised continuum models of Kresling origami metamaterials. • We present some numerical simulation concerning metamaterials based on Kresling tube pattern. • Numerical analyses of some selected tests clarifies the mechanical behaviour of metamaterials based on Kresling pattern. • Numerical simulations address the homogenised model of Kresling tubes. [ABSTRACT FROM AUTHOR]

A high-pressure hydrogen micromix combustor has been investigated using direct numerical simulation with detailed chemistry to examine the flame structure and stabilisation mechanism. The configuration of the combustor was based on the design by Schefer et al. [1] , using numerical periodicity to mimic a large square array. A precursor simulation of an opposed jet-in-crossflow was first conducted to generate appropriate partially-premixed inflow boundary conditions for the subsequent reacting simulation. The resulting flame can be described as an predominantly-lean inhomogeneously-premixed lifted jet flame. Five main zones were identified: a jet mixing region, a core flame, a peripheral flame, a recirculation zone, and combustion products. The core flame, situated over the jet mixing region, was found to burn as a thin reaction front, responsible for over 85% of the total fuel consumption. The peripheral flame shrouded the core flame, had low mean flow with high turbulence, and burned at very lean conditions (in the distributed burning regime). It was shown that turbulent premixed flame propagation was an order-of-magnitude too slow to stabilise the flame at these conditions. Stabilisation was identified to be due to ignition events resulting from turbulent mixing of fuel from the jet into mean recirculation of very lean hot products. Ignition events were found to correlate with shear-driven Kelvin–Helmholtz vortices, and increased in likelihood with streamwise distance. At the flame base, isolated events were observed, which developed into rapidly burning flame kernels that were blown downstream. Further downstream, near-simultaneous spatially-distributed ignition events were observed, which appeared more like ignition sheets. The paper concludes with a broader discussion that considers generalising from the conditions considered here. [ABSTRACT FROM AUTHOR]

This paper presents a novel self-centering energy dissipating RC rocking column (SCERC) in which a steel tube protects the concrete from spalling and crushing at the column base. It incorporates an easily repairable pre-pressed disc spring self-centering device (SC) to restore the rocking column to its original position and a straightforward slip friction energy dissipation device (ED) to ensure adequate energy dissipation capacity. The working principle of the SC was investigated, and an analytical method was proposed. Subsequently, a theoretical hysteresis model for the SCERC considering different limit states is developed through reliable analyses. Lastly, the preliminary design parameters of the SCERC were determined, with numerical simulations conducted to validate the theoretical model. These simulations aim to explore the hysteresis characteristics, energy dissipation capabilities, and self-centering performance of the SCERC under different axial pressures and self-centering ratios. The results indicate that the theoretical hysteresis model was consistent with the numerical simulations, revealing that the SCERC exhibits a "flag-shaped" hysteresis response. The proposed SCERC displays satisfactory energy dissipation and self-centering characteristics. The SC provide sufficient restoring forces, with the EDs accounting for much of the energy dissipation. Plastic deformation was not observed in the concrete column, except for the unavoidable deformation occurring in the steel tube at the point of rotation. While a rocking column naturally possesses self-centering capabilities under axial forces, it requires SCs to counteract the negative stiffness caused by the P -∆ effect. As the self-centering ratio decreases, both the load capacity and energy dissipation capacity of the SCERC increase, leading to an increase in the residual deformation of the column; hence, the design should balance these two aspects for a suitable self-centering rate. • A rocking column with pre-pressed disc springs and enhanced column base is proposed. • A theoretical hysteresis model for different limit states is established. • Design parameters of the rocking column is investigated. • A numerical simulation is conducted to explore the resilient property. [ABSTRACT FROM AUTHOR]

The packing is the core heat transfer unit in the cooling tower. To improve the heat and mass transfer performance of the counterflow wet cooling tower, a new double S-wave structure packing is proposed in this paper, and its performance in heat-mass exchange is investigated using a combination of numerical simulation and experiment. The flow heat transfer performance of the double S-wave packing with different sheet spacing, tilt angle and inlet area is studied by numerical simulation, and the law of different structural parameters affecting the packing is derived to determine its optimal structure. The thermal and resistance performance of double S-wave packing and conventional double-folded packing under different working conditions were studied in comparison with each other by building an experimental bench. The results show that the cooling efficiency of double S-wave packing is 13.74% higher and the pressure drop is 3.58% lower than that of double-folded packing. The research results can provide important guidance and reference for engineering practice. [ABSTRACT FROM AUTHOR]

• Mechanical response characteristics of beam-column substructures exposed to fire are analyzed. • Explicit calculation formulas for determining the collapse resistance are derived in detail. • Proposed theoretical calculated formulas agree well with these from numerical simulations. • Error analysis is conducted to reveal deviation reasons between theoretical model and numerical simulations. This paper provides a simplified analytical model for the restrained steel beam-column substructure under a fire-induced progressive collapse scenario, which is applied to predict the collapse resistance of substructures under fire. The simplified model is formulated for axially and rotationally restrained two-span steel beam-column substructures under column-loss scenarios and involves rigid and semi-rigid connections. The response characteristics of restrained substructures exposed to fire under column-loss scenarios in each response stage are elaborately analyzed. A "negative" catenary stage, in consideration of the unique negative axial force effects induced by the temperature thermal expansion, was first introduced in the five-stage simplified model for restrained substructures exposed to fire against progressive collapse. Subsequently, the explicit calculation formulas for determining the vertical loads and deflection of both rigid and semi-rigid joint substructures exposed to fire were derived in a quantified way, based on rigid-plastic mechanisms and restraint coefficient methods. In addition, the corresponding numerical simulation analysis on a restrained two-span steel beam-column substructure with different end constraints and fire conditions was carried out to verify the applicability and reliability of established theoretical formulas. Comparisons of vertical load-deflection relationships between the calculation formulas and corresponding numerical simulation shows good accuracy. For more accurate prediction results, the error analysis was further conducted, and several theoretical formulas were modified, which were verified to be accurate and reliable after correction. With derived resistance functions, the resistance of steel beam-column substructures in fire-induced progressive collapse scenarios can be predicted. [ABSTRACT FROM AUTHOR]

Soundless Cracking Demolition Agents (SCDA) are gaining traction as an innovative technique for controlled rock fracturing in applications such as underground energy, mineral extraction, and excavation. This paper presents a novel numerical approach to simulate SCDA-charged rock fracture initiation using the strain energy density of SCDA. This approach eliminates the need for prior knowledge of the peak expansive pressure developed in a rock, a common requirement in conventional SCDA modelling. An empirically derived model is presented which captures the rate of energy release in SCDA as a function of applied strain to the surrounding material. The model was implemented in the 3-dimensional Distinct Element Code by applying an exponential strain-rate decay function. The proposed fracture stimulation method accurately mimics the expansion behaviour and finite strain energy release from SCDA expansion. The method was extended to simulate SCDA expansion in rock joints. The SCDA expansion method was assessed by creating a numerical model in which a central injection well was intersected by a horizontal joint and SCDA expansion was simulated in the injection well and the joint. The simulations were verified against laboratory fracture experiments. The model was extended to evaluate the fracturing performance of SCDA under varying joint roughness and confining pressures. SCDA expansion in rock joints introduces an additional compressive stress field that inhibits fracture initiation and propagation near the joint. Increasing fracture roughness suppressed fracture growth, but led to more fracture nucleation points around the injection well and shear damage at the joint interface. The simulation method employed shows sensitivity to confining pressures and simulates the fracturing potential of SCDA in different rocks subjected to confining pressures without requiring further calibration of the SCDA expansion parameters. The proposed numerical simulation method improves the accuracy in investigating the fracturing potential of expansive agents over existing simulation methods for SCDA. [ABSTRACT FROM AUTHOR]

In this paper, a novel numerical simulation approach based on the finite element method for dynamically modeling the excavation process of shield tunneling is proposed, with the shield-ground interactions well captured. This method is capable of mimicking the alternating modes of advancing and stopping of a shield boring machine during underground construction, with the important effects of the cutterhead rotation and slurry support pressure considered. Under the cutting action, the soil at the excavation face would experience irreversible deformation and damage, such that additional support needs to be provided by the cutterhead blades and slurry to maintain stability. The impacts of key construction parameters are examined, including cutterhead rotary speed, advance rate, and slurry support pressure, on shield tunneling operations and ground responses. The numerical model is rigorously validated against physical model experiments. This work provides useful insights into the mechanistic processes in the stratum during shield tunneling, including the spatiotemporal evolution of ground deformation patterns and stress redistributions. The results offer valuable guidance for optimizing shield tunneling operations and enhancing tunneling safety and efficiency. [ABSTRACT FROM AUTHOR]

For the integrated design of the forebody and hypersonic inlet, the non-uniform inflows generated by the forebody have significant impacts on the inlet performance. Traditional inlet designed by the Internal Conical Flow C (ICFC) flowfield or Method of Characteristics (MOC) flowfield, is difficult to match non-uniform inflows, which can easily lead to reduced captured flow and total pressure recovery. Hence, this paper proposes a novel design method for inward-turning inlets to overcome these problems. The key of this method is the parent flowfiled called the Internal Conical Flow N (ICFN). A multi-objective design optimization is integrated into the design of the two-dimensional ICFN flowfield, which enables the "design-optimization" to implement simultaneously. The new ICFN flowfield makes full use of the high compression effect and avoids the existence of Mach reflection at the focal point. Complete details of the design method of ICFN flowfield and inward-turning inlet are presented. The flowfield structure of ICFN flowfield and inlet are analyzed. Numerical simulation results indicate that the new inward-turning inlet can effectively increase captured flow and total pressure recovery. This reveals that the design method gained here can be usefully applied to the design of high-performance inward-turning inlets. [ABSTRACT FROM AUTHOR]

This paper investigates the stability control of the tethered multi-rotor unmanned aerial vehicles (T-MRUAVs) system in cargo delivery, where precise payload trajectory control is deemed unnecessary, with a focus on enhancing controller simplicity and robustness. To achieve this objective, it is imperative to employ an optimal formation tracking control, ensuring not only the symmetrical positioning of UAVs concerning the payload but also the achievement of distributed optimal solutions. Therefore, a formation tracking control strategy based on differential graphical games is designed to ensure optimized performance metrics and minimized suspended load swing. The designed control framework includes an outer loop and an inner loop control, which respectively achieve formation tracking and attitude stability. In addition to maintaining equilibrium states, each UAV is required to track the desired trajectory. Consequently, the formation tracking control consists of a gravity compensation term at the equilibrium point and a formation tracking control term based on differential graphical games. Then, a PID control strategy is displayed for the inner loop control, and the altitude control adopts feedback linearization. Finally, numerical simulations have validated the effectiveness of the designed algorithm. [ABSTRACT FROM AUTHOR]

Due to mosquito habitat heterogeneity, its directional movement has been observed. In this paper, we develop a reaction–advection–diffusion model to explore mosquito populations suppression with sterile insect technique in spatially heterogeneous environments. By employing theoretical analysis, we show that the dynamic behavior of mosquitoes is closely related to their directional movement when the sterile mosquito amount is small. Numerical simulations further verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • At a same depth in concrete prism, the moisture content and sulfate concentration are higher at the diagonal of the prism. • There is no clear demarcation between ion convection and diffusion zones in concrete prism under dry-wet cycles. • The longer the wetting time in one dry-wet cycle, the deeper the spalling of concrete prism caused by sulfate attack. External sulfate attack (ESA) coupled with wetting–drying alternation poses a significant threat to the concrete durability, while there are few models to simulate the above ESA behavior. In this paper, a simplified transport-mechanical model is proposed to numerically analyze the deterioration of concrete prism under ESA and dry-wet cycles. Firstly, a transport model of sulfate ion in concrete prism is established by considering the behaviors of ion diffusion, convection and chemical reaction, and numerically solved by the finite difference method. Secondly, the crystallization pressure of sulfate products in porous system is analyzed to calculate the equivalent expansion force. Then, the expansion strain and its-induced damage are calculated, and the criterion of boundary movement is further proposed. On the basis of model validation, a numerical simulation is performed to analyze the transport-mechanical response in concrete prism under ESA and dry-wet cycles. The results show that, there is no clear demarcation between the convection and diffusion zones in the prism. The spatial–temporal evolution of ESA-induced damage is similar to that of ion concentration. The longer the wetting time in one dry-wet cycles, the deeper the spalling of concrete prism caused by ESA. [ABSTRACT FROM AUTHOR]

Simulation of the failure process of non-intact rock containing initial cracks, voids, and other discontinuities is a research hotspot in rock mechanics and geotechnical engineering. The damage smear method has attracted wide attention due to its ability to realistically depict the complete failure processes of rock from the microscopic to the macroscopic scale. However, when portraying pre-existed discontinuities, the damage smear method suffers from major difficulties such as mesh dependency and stress singularity. To overcome the limitations of current methodology, this paper proposes a novel non-break modeling strategy inspired by the extended finite element method for dealing with embedded discontinuities, in which the discontinuity of the physical fields across crack faces or the void boundary, as well as the stress singularity at the crack tip, can be characterized by introducing appropriate enrichment functions, and the penalty method is used to impose frictional contact constraints. Applications of the combined method of the improved modeling strategy and damage smear analysis to laboratory-scale and engineering-scale numerical examples show a satisfactory approximation with the analytical solution or experimental observations, indicating that the current modeling strategy can further improve computational accuracy while retaining the advantages of the damage smear method. [ABSTRACT FROM AUTHOR]

• An explosion test of a cylindrical casing for AISI9260 is conducted, and the mass distribution of fragmentation is successfully obtained. • Fracture strains at shear, uniaxial tension, and plane strain are obtained at various strain rates from 0.001 to 1500/s, and strain-rate dependent fracture surface are successfully modelled. • The algorithm for fragment mass distribution is developed. • Fragmentation simulation is performed, and the predicted mass distribution show good agreement with the experimental result. • The groove pattern is changed, and more uniform fragments are predicted. This paper presents experimental and numerical studies on the controlled fragmentation of AISI9260 casing under internal explosive loading condition. The cylindrical casing has internal circumferential grooves to get a uniform size of fragments. In order to investigate the fragmentation performance, a fragment mass distribution is obtained from the experiment. Experimental results show that the fragments are created in various sizes. For the material characterization, the mechanical tests are conducted at various strain rates to understand the material dynamic behaviors. For the dynamic hardening behavior, the flow stress increases when the strain rate increases. The stress states and strain rates are considered for the dynamic fracture behavior. Each stress state shows a different strain rate effect. The extended Lim–Huh and Lou–Huh fracture models successfully describe the dynamic hardening and fracture behaviors, respectively. Then, the numerical simulation is performed to figure out the deformation and fragmentation processes. The fragment mass distributions from the experiment and simulation show good agreement with each other. Moreover, the distance between grooves has increased to achieve the uniform size of fragments. It is confirmed that the distance between grooves is a crucial factor for uniform fragments. [ABSTRACT FROM AUTHOR]

In this paper, the Grammian solutions for the BKP equation are employed to investigate the inelastic interaction solutions between multiple-lump molecule and kink solitons. Various kinds of interaction solutions including 2-, 3-lump molecule and 1-, 2-, 3-kink solitons are obtained. The dynamical behaviors of these interaction solutions are analyzed by means of the numerical simulation. A general procedure is proposed to construct the inelastic interaction solutions between M -lump molecule and L -kink solitons. As the parameter increases, the structure of lump molecule is gradually destroyed, and the multiple lump waves will form a triangular structure. L lump waves are absorbed by the L -kink solitons after the interaction. The results are helpful for us to understand the complex inelastic interaction dynamics between the lump molecules and solitons. [ABSTRACT FROM AUTHOR]

The cylindrical slide valve is an essential component of the hydraulic system, which regulates and controls the oil. When hydraulic oil flows through the slide valve port, cavitation often occurs due to a sharp pressure drop, affecting the hydraulic system's stability. Therefore, the study of cavitation phenomena in valves is an important topic. This paper conducts a transient numerical simulation of the three-dimensional multi-physics field in the valve under different inlet pressure and oil temperature conditions and studies the effects of different inlet pressures and oil temperatures on the oil's temperature rise and cavitation phenomenon at the valve port. The results show that under high-pressure differences, the temperature of hydraulic oil rises significantly. In addition, the increase in oil temperature will significantly affect the cavitation intensity in the valve. When the oil temperature is 330 K, the severity of cavitation in the valve under a pressure of 5 MPa is roughly the same as when the oil temperature is 300 K, and the inlet pressure is 15 MPa. Under different inlet pressure and oil temperature conditions, the pressure pulsation in the slide valve is also very different. Under certain working conditions, the peak power spectrum density of the pressure pulsation is close to the hydraulic natural frequency, which may cause the slide valve to self-excited oscillation. Therefore, it is recommended that under actual working conditions, the oil temperature should be lowered in time to reduce the adverse effects of valve port cavitation. • A mathematical model of cavitation coupled with temperature fields was developed. • The high-pressure drop at the valve port causes the hydraulic oil temperature to rise significantly. • As The oil temperature increases, the cavitation phenomenon in the valve increases significantly. • Under certain working conditions, the pressure pulsation frequency caused by cavitation is close to the hydraulic natural frequency. [ABSTRACT FROM AUTHOR]

This paper derives the theoretical equations to calculate the stiffness, strength, and yield displacement of the tall RC two-column piers with and without BRBs. A structural fuses-based design method was proposed to design the tall RC two-column piers with and without BRBs, and the corresponding scale models were designed and constructed. The numerical simulations and shaking table tests were separately conducted to verify the reasonable of the derivation theoretical equations and proposed design method and validate the effects of BRBs on controlling the seismic response and damage of the tall RC two-column pier. The seismic responses, including displacement and curvature, were discussed when the tall RC two-column piers with and without BRBs were subjected to different seismic waves. These results indicate that the BRB remarkably decreases the displacement and curvature of the column due to the BRBs yielding and dissipating the seismic energy. The seismic damage based on the yield curvature occurs in the tall RC two-column pier without BRBs, while the tall RC two-column pier with BRBs does not experience seismic damage under the design seismic waves with 0.4 g. Therefore, the BRBs can effectively control seismic damage and make the tall RC two-column pier satisfy the performance target according to the structural fuses concept. Also, the tall RC two-column piers with and without BRBs undergo seismic damage under the E2 earthquakes with 0.68 g. However, the curvature responses of the tall RC two-column pier with BRBs are far less than the tall RC two-column pier without BRBs under the E2 earthquakes. Consequently, BRBs can improve the seismic resilience of tall RC two-column piers. • Theoretical equations were derived for the strength and stiffness of a tall RC two-column pier with BRBs. • Dynamic simulations and tests were conducted for tall RC two-column piers with and without BRBs. • Seismic responses were compared for tall RC two-column piers with and without BRBs. • Theoretical equations were validated using dynamic simulations and tests. • BRBs effects on controlling seismic damage to tall RC two-column piers were verified. [ABSTRACT FROM AUTHOR]

[Display omitted] • A family of multi-layer multistable metastructures is proposed that can realize deformation with multiple degrees of freedom, benefiting from the single-layer unit that is capable of inclining a certain angle in four directions. • The inclined stable state is triggered by the lateral compression, and the transitions between different stable states exhibit different load–displacement responses. • The load–displacement responses of double-layer units are the superposition of those of single-layer units. • The planar or spatial bending postures are realized in the multi-layer, multistable metastructures. This paper proposes a family of multi-stable metastructures with multiple layers, which possess the capability of multi-degree of freedom deformations. In its single layer, four preshaped beams connecting two frames are employed as the main component for the design of multi-stable metastructures. Compared with the traditional flat state obtained by axial compression when all beams snap through, four inclined stable states are easy to trigger by lateral compression at a local position when two adjacent beams snap through. The transitions between these states are studied by both experiments and numerical simulation. The transition to inclined states requires less energy than the transition to the flat state. Different trends of load–displacement responses are associated with loading positions and transitions. A parametric analysis is performed to illustrate the relationship between the stability of inclined states and critical parameters, such as span, apex height, and thickness. Two types of hourglass double-layer units are designed and studied through experiments. The continuous transitions in two steps or three steps are observed, and the load–displacement response is the accumulation of responses from each single layer. At last, two multi-layer structures with multi-stability have been developed to demonstrate their deformation capability in multiple directions through multiple steps. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes/polydimethylsiloxane (MWCNTs/PDMS) composites have excellent electromechanical conversion ability which can be applied in the field of intelligent sensing. However, the volume changes and electromechanical response mechanism of MWCNTs/PDMS under dynamic load remain unclear. In this paper, the electromechanical response of MWCNTs/PDMS with different mass ratio of MWCNTs are studied by quasi-static compression, SHPB experiment and finite element numerical simulation. The quasi-static compression results show that volume ratios of MWCNTs/PDMS are decreased with compression strain (0.845 when strain is 0.5), then, the Yeoh hyperelastic constitutive model is established considering volume change. When the mass ratio of MWCNTs is 1 wt%, MWCNTs/PDMS shows the best mechanical properties. The stationary phases of strain rate of MWCNTs/PDMS decrease with increasing of impact velocity, showing obvious viscoelastic mechanical properties. The impact induced voltages of MWCNTs/PDMS are generally larger than PDMS (10∼15 m/s). The flexoelectric effect of MWCNTs/PDMS under impact is further studied based on numerical simulations. The results show that the strain gradients are within 10−2∼10−1 m−1, the related flexoelectric coefficients are within 10−10–10−9 C/m. In summary, this study can further expand the application of MWCNTs/PDMS in the field of intelligent sensing. • The constitutive model of MWCNTs/PDMS composites considering volume change is established. • The impact induced flexoelectric effect of MWCNTs/PDMS is mainly related to strain gradient ∂ ε z z / ∂ x z. • CNTs 1wt% /PDMS composite has the largest flexoelectric coefficients: μ zzzz = 6.447 × 10−9 C/m, μ xxzz = −6.04 × 10−10 C/m, μ xzxz = 1.23 × 10−10 C/m. [ABSTRACT FROM AUTHOR]

• A modified GTN model considering the effects of anisotropy and shearing on micropore evolution is introduced. • The constitutive model is compiled into a VUMAT subroutine for numerical simulation to accurately predict the plastic deformation of aluminum alloy sheet. • The parameters in constitutive model are calibrated by inverse FE method and the validity of the modified GTN model is verified through the uniaxial tensile experiment. • A FE model of the mould-sheet coupling system is further developed to improve the forming performance. Traditional GTN meso-damage model, neglecting the effect of anisotropy or shearing on the evolution of microvoid, leads to the lower predictive capabilities of forming defects for aluminum alloy sheets. In this paper, a modified constitutive model of aluminum alloy sheet considering the effect of both anisotropy and shearing is proposed, and the corresponding model parameters are calibrated by inverse finite element method and uniaxial tensile test of the smooth strip sheet without hole. Then, the constitutive equation of the modified model is compiled into a VUMAT subroutine using backward Euler integration algorithm and FORTRAN language to perform subsequent numerical simulation in ABAQUS/Explicit, the validity of the proposed shear-corrected GTN model is also verified through the uniaxial tensile experiment of the strip sheet with a hole in the middle. Finally, finite element (FE) model of the mould-sheet coupling system is developed based on the modified GTN model, and the influence of punching speed, blank holder force, friction coefficient and dwell time on the forming performance of AA5052 aluminum alloy sheet is investigated. The results show that ductile fracture of aluminum alloy sheet is most prone to exist on the upper fillet of part. [ABSTRACT FROM AUTHOR]

• A macroscale model is developed to study electrostatic particle filtration. • Multi-layering is proposed as a means of protecting the bipolarly charged fibers. • Unipolar and bipolar charging are considered to lower the pressure drop. • Placing the unipolar layer upstream of the bipolar layer extends filter's life. The deposition of neutral and charged particles inside an electrostatically charged filter can affect its performance by decreasing its ability to capture additional particles and by increasing its pressure drop. The particle-loaded behavior of a composite filter comprised of three fibrous layers is studied in this paper using a macroscale simulation approach. Each of these fibrous layers were assumed to have fibers with the same amount of charge but different charge polarities of only unipolar positive, only unipolar negative, or only bipolar. The charged layers were stacked on top of one another in three different configurations with respect to the flow direction and their filtration efficiency and pressure drop were compared during particle loading with neutralized particles (having the Boltzmann equilibrium charge distribution), singly-charged particles, and neutral particles. Our simulations revealed that placing the bipolarly-charged layer downstream of the unipolarly charged layers helps to lower the negative impact of particle deposition on pressure drop and filtration efficiency of the resulting composite filter. This study introduces a design tool which can be used to optimize the configuration of a composite filter for enhanced particle capture efficiency and reduced pressure drop increase. [ABSTRACT FROM AUTHOR]

The characterization of the constitutive mechanical behaviour of Fabric Reinforced Cementitious Composites (FRCM) is a widely discussed topic in the scientific community. Several research studies pointed out the difficulties in assessing reliable constitutive laws able to reproduce the local phenomena inner in the mechanics of FRCM materials. This paper presents the proposal of a model updating procedure based on a Genetic Algorithm (GA), able to obtain the parameters to be used for a simplified numerical modelling of the fabric-to-matrix interface. The procedure is applied to a truss-based Finite Element (FE) model, and it aims to minimize the difference between the simulations and the experimental results. The calibration procedure is performed against a large experimental database of bond tests in FRCM-to-masonry assemblies, allowing to express the model parameters as a function of geometrical and mechanical characteristics of the FRCM. • FRCM-to-masonry bond is studied. • A simplified FE model is proposed. • A GA-based model updating procedure is implemented. • Comparisons with experimental results prove the efficacy of the procedure. [ABSTRACT FROM AUTHOR]

This paper presents an approach for developing Reduced Order Models (ROMs) of complex geomechanical systems from high-fidelity numerical simulations. The approach uses proper orthogonal decomposition of the state variables for the model reduction, combined with long short-term memory neural networks to update the simulations in response to changing boundary conditions. A key challenge in creating these models is the need to efficiently sample the system state during training and testing. Too few (or poorly distributed) training simulations yields inaccurate models, while too many results in wasted effort. However, the exact number required is difficult to determine ahead of time, as it is both context and model dependent. Here, we present a bootstrap strategy to estimate the number of simulations required to develop the reduced order model. The strategy uses an iterative approach in conjunction with a quasi-random sampling technique to ensure consistent coverage of the sample space. We demonstrate the approach by developing a ROM describing the coupled hydro-mechanical response of a section of an open-cut coal mine. Excellent agreement is achieved between the resulting reduced order model and the original high-fidelity simulation for significantly less computational effort. • A bootstrap strategy to develop Reduced Order Models for geotechnical problems is presented. • The approach uses a quasi-random iterative strategy to sample the state space. • We apply the approach to a complex multiphysics model of a mine slope. • The computational cost of modelling the slope is significantly reduced. [ABSTRACT FROM AUTHOR]

Test duration in gun tunnels is on the order of several milliseconds, so its extension is crucial for easier and more accurate experimental measurement. However, there is a lack of reported work on the physical mechanisms governing the test time in gun tunnels. To address this issue, this paper explored the influence of the length of the driver section (L 4), the driven section (L 1), and the pressure ratio (P 4 /P 1) between the driver and the driven section on the test time of gun tunnels through numerical simulations. It is found that the starting point of test time is related to the moment of the 4th shock wave arrival, and the end point corresponds to the event of piston or expansion wave arrival, depending on which one happens first. Furthermore, in order to obtain the maximum test time for a gun tunnel, the ratios of the length and the pressure between the driver and the driven section need to be adjusted so that the piston and the expansion waves can arrive at the end of the driven tube simultaneously. When L 4 /L 1 and P 4 /P 1 is larger than the optimal value, the piston reaches the end of the driven tube faster than the expansion waves. This is because the velocity of the piston is higher while that of the expansion waves is basically unchanged at larger P 4 /P 1. In addition, the distance for the expansion waves to travel is longer at bigger L 4. On the contrary, when L 4 /L 1 and P 4 /P 1 is smaller than the optimum, the expansion waves hit the end of the driven section before the piston. [ABSTRACT FROM AUTHOR]

In this paper, we study the spreading speed and traveling wave of an impulsive reaction–diffusion model with non-monotone birth function and age structure, which models the evolution of annually synchronized emergence of adult population with maturation. Our result is an extension to that recently established in Bai, Lou and Zhao (J. Nonlinear Sci. 2022). Numerical simulations are also performed to illustrate our result. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical solution for bond-slip behavior of SRC interface based on experiment, numerical simulation, and theoretical derivation. Push-out tests of five specimens were firstly carried out, based on which, the simplified bond-slip model was proposed. The specimen was fabricated using the Q345H-shape steel (400 mm × 200 mm×13 mm × 8 mm) and C50 concrete (350 mm × 600 mm) with a bonding length of 500 mm. A FE model was established based on the bond-slip model to analyze the nonlinear bonding stress that are difficult to obtain from the experiment. The research shows that although the bonding stress in the elastic stage is not uniformly distributed, it is basically uniformly distributed when the ultimate bearing capacity is reached. It proves that assuming the average interfacial bonding stress under ultimate load to replace the maximum bonding stress is reasonable, which is crucial for designer to estimate interface bearing capacity and maximum bonding stress. Moreover, five different stages were obtained by the FE model analysis and the theoretical equations of bonding stress nonlinear distribution were obtained based on the boundary condition of each stage. The theoretical solution clearly showed the relationship between interface nonlinear stress distribution and influencing parameters including the bond area, elasticity modulus of material, section area of specimen, bond-slip constitutive model, and the external load. Based on the theoretical model, the influences of different parameters can be directly obtained without conducting further experiments and establishing different FE models. • The simplified bond-slip model was proposed and nonlinear distributiion of interfacial bonding stress was analyzed. • Assuming the average interfacial bonding stress under ultimate load to replace the maximum bonding stress is reasonable. • Corresponding analytical formulas for the interfacial stress in five different stages were established, respectively. • The theoretical solution showed the quantitative relationship between interface nonlinear stress and influencing parameters. [ABSTRACT FROM AUTHOR]

The particle sedimentation and phase change in the mushy zone are accompanied by a variety of complex transfer processes involving momentum, heat, and mass. It is very important to investigate the coupling process of particle settling and melting in the mushy zone for revealing the mechanism of the solid-liquid phase change. In this paper, the motion process and heat transfer characteristics of an elliptic particle as well as two particle interactions in the vertical channel were solved by the finite element method with the consideration of coupling of the phase change and motion. The Arbitrary Lagrangian-Euler Method (ALE) was employed to track the interface of the moving particle and fluid. Results show that the elliptical particle settles along the channel's center line vertically under gravity and undergoes phase change simultaneously. Uneven velocity and temperature fields surrounding the particle are generated by sedimentation, resulting in the particle with an irregular shape. When the initial position of the particle deviates from the center line, the particle deflects during the sedimentation and shifts both left and right in the X -direction. The different initial angles of settling also affect the sedimentation velocity and melting rate. When two particles settle simultaneously, they will lead to complex movement and heat transfer due to the interaction between each other. If the arrangement is eccentric, both particles undergo complex deflections during sedimentation, leading to different melting rates for the two particles. [ABSTRACT FROM AUTHOR]

The paper introduces a practical method for the construction of large-scale point sets for analysis of computer models. The constructed experimental design is useful for (probabilistic) integration, construction of approximation or a screening. The essence of the presented approach is the stratification of the design domain into an orthogonal grid of substrata and a subsequent tiling with tiles of points. If optimized, such tiles experience a major reduction of the number of degrees of freedom in the optimization process. That way, optimal or near-optimal point patterns can be feasibly identified and are further utilized for construction of larger point sets, thanks to the idea of self-similarity and structured space stratification The space-filling properties of the resulting point sets may be further enhanced by various "scrambling" strategies, which may remove the undesired sample collapsibility achieved via regular tiling. The performance of the constructed point sets is compared to Quasi Monte Carlo (QMC), Randomized Quasi Monte Carlo (RQMC) sequences, which are still today considered by engineers and even scientists as choices for variance reduction of numerical integration Further, the mentioned sampling strategies are compared in the terms of robustness when integrating a multivariate function with a localized feature. It is concluded that the proposed sampling approach reaches a superior performance in numerical integration and identification of function extremes as compared to sampling methods used by practicing researchers and engineers. Additionally, the reader is supplied with the open-access, ready-to-use implementation of the presented algorithm named SampleTiler. • Construction of large-scale point samples by balancing the bias–variance tradeoff. • Stratification of the design domain and subsequent tiling with tiles of points. • Construction of large optimized experimental designs due to self-similarity. • Superior performance of samples as compared to commonly used methods. • Open-access Python code provided on a GitHub repository. [ABSTRACT FROM AUTHOR]

The working environment of industrial fields where the Particulate Reinforced Composites (PRCs) are commonly used is complex. In these harsh environments, PRCs produce some nonlinear strains, such as plastic, thermal, and creep strains, which affect the performance of PRCs to some extent. In addition, the actual structure of PRCs contains a massive amount of inclusions, and the number of inclusions could reach the magnitude of millions or even tens of millions. For the large-scale numerical simulation of PRCs, ordinary displacement finite element requires a large number of meshes, which increases their computational complexity and unsolvability. For real PRCs with random particle distribution, homogenisation theory does not accurately capture the true state of stress concentration in PRCs. The Voronoi cell finite element method (VCFEM) can be a good solution to the drawbacks of the above two numerical simulation methods. The subject of the present work explores a modified complementary energy generalized function that takes the constitutive relationship of nonlinear strain into account, proposing a two-dimensional VCFEM, formulated with plastic, thermal, and creep strain. The simulation results are compared with the computed results of a commercial finite element software Marc to verify the validity and accuracy of the VCFEM. Results of the comparison show that the VCFEM has the advantages of simple meshing and faster computation under the same precision. The VCFEM, considering plastic, thermal, and creep strains proposed in this paper, lays the foundation for future large-scale numerical simulations of PRCs containing a large quantity of inclusion structures and can realistically capture the stress concentration state of PRCs. At the end of the article, the impact of the order of stress function on the calculation results is discussed. [ABSTRACT FROM AUTHOR]

In this paper, the intra-day multi-interval rolling-window joint dispatch and pricing of energy and reserve is studied under increasing volatile and uncertain renewable generations. A look-ahead energy-reserve co-optimization model is proposed for the rolling-window dispatch, where possible contingencies and load/renewable forecast errors over the look-ahead window are modeled as several scenario trajectories, while generation, especially its ramp, is jointly scheduled with reserve to minimize the expected system cost considering these scenarios. Based on the proposed model, marginal prices of energy and reserve are derived, which incorporate shadow prices of generators' individual ramping capability limits to eliminate their possible ramping-induced opportunity costs or arbitrages. We prove that under mild conditions, the proposed market design provides dispatch-following incentives to generators without the need for out-of-the-market uplifts, and truthful-bidding incentives of price-taking generators can be guaranteed as well. Some discussions are also made on how to fit the proposed framework into current market practice. These findings are validated in numerical simulations. • A scenario-oriented rolling-window co-optimization model of energy and reserve is proposed. • Marginal prices of energy and reserve are derived, which incorporate shadow prices of generators' ramping limits. • Dispatch-following and truthful-bidding incentives of generators are guaranteed. [ABSTRACT FROM AUTHOR]

• A novel polar mechanical metamaterial with dual deformation features. • The proposed polar mechanical metamaterial has opposite mechanical properties on coaxially opposite surfaces. • The proposed polar mechanical metamaterials are characterized by two-step deformation. • The polarity characteristic spectrum of the mechanical metamaterial is identified. • The theoretical prediction formulas for the load platform of polar mechanical metamaterials are developed. Polarity refers to the phenomenon of an object exhibiting opposite intrinsic properties in opposing directions, which plays a fundamental role in various fields including mechanical diodes, mechanical logic gates, and shock protection. This paper proposes a new mechanical metamaterial with polar and dual deformation characteristics based on a fishbone-like structure to enable a given surface structure to be hard while its opposite side is soft, while also enabling the task of adapting to different load levels on the soft side. The mechanical metamaterial displays double-stress platforms and exhibits a significant difference in mechanical response when loaded on opposite sides. Through numerical simulations, the polarity characteristic spectrum of the mechanical metamaterial is identified. The stress platform with a soft boundary predicted using Euler's instability theory was verified through both numerical simulation and experimentation. The dimensionless parameters for load differences are defined to evaluate the polar characteristics of polar mechanical metamaterials, and design guidelines are provided for achieving significant polar characteristics of polar mechanical metamaterials by discussing the influence of geometrical parameters. The proposed polar mechanical metamaterial introduces a novel design concept applicable to signal transmission, isolation, and energy absorption for different load levels. [Display omitted] [ABSTRACT FROM AUTHOR]

Surface ruptures resulting from seismic faulting have the potential to inflict substantial damage to bridges straddling fault lines; hence, it is imperative to investigate the impact of ground motions documented on either side of fault rupture planes—termed as across-fault ground motion—on the seismic resilience of bridges. In this paper, the object of study is a three-span, simply supported beam bridge traversing a strike-slip fault. Utilizing the LS-DYNA finite element software platform, a sophisticated three-dimensional finite element model of the selected bridge is constructed, meticulously accounting for material damage nonlinearity and structural collision contact nonlinearity. A synthetic across-fault ground motion serves as the excitation for the seismic analysis of the bridge, systematically examining the influence of the fault-crossing angle (FCA), fault sliding rise time, and ground surface permanent rupture displacement on the dynamic response and seismic damage incurred by the simply supported beam bridge. The findings demonstrate that a diminutive fault-crossing angle (FCA) corresponds to an elevated risk of longitudinal beam collapse when a simply supported beam bridge does not intersect a fault vertically. The impact of the fault sliding rise time on the magnitude of seismic response and damage sustained by the simply supported beam bridge is relatively minuscule and can be neglected. Conversely, the ground surface permanent rupture displacement profoundly influences the dynamic response and seismic damage of the bridge. The emergence of fling-step pulses from the development of ground surface permanent rupture displacement amidst seismic activity induces a shift in failure mode-from the designer-intended bending failure to an unforeseen shear failure. • A FE model of a simply-supported beam bridge is established with consideration of material and contact nonlinearity. • The systematic parameter analysis of the simply-supported beam bridge is conducted. • The failure mode and damage process of the simply-supported beam bridge are revealed. • Recommendations for the seismic design of simply-supported beam bridges subjected to strike-slip faulting are drawn. [ABSTRACT FROM AUTHOR]

This paper presents a multi-temporal formulation for simulating elastoplastic solids under cyclic loading. We leverage the proper generalized decomposition (PGD) to decompose the displacements into multiple time scales, separating the spatial and intra-cyclic dependence from the inter-cyclic variation. In contrast with the standard incremental approach, which solves the (non-linear and computationally intensive) mechanical balance equations at every time step, the proposed PGD approach allows the mechanical balance equations to be solved exclusively for the small-time intra-cyclic response, while the large-time inter-cyclic response is described by simple scalar algebraic equations. Numerical simulations exhibiting complex cyclic responses, including a 2D problem and an application to a monopile foundation, demonstrate that PGD solutions with a limited number of space–time degrees of freedom may be obtained numerically, only requiring a few modes to accurately capture the reference response. [ABSTRACT FROM AUTHOR]

An integrated attitude and orbit finite-time control based on anti-unwinding twistor representation for flying-around with non-cooperative target is proposed in this paper. Firstly, an integrated attitude and orbit model based on traditional twistor representation is established for non-cooperative flying-around problem with complex initial situation. Secondly, an anti-unwinding representation is proposed to avoid the unwinding phenomenon. Thirdly, a finite-time controller in the framework of the anti-unwinding twistor representation is designed to guarantee the spacecraft to reach the desired state quickly. Finally, the effectiveness of the proposed method is verified by numerical simulations. [ABSTRACT FROM AUTHOR]