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In the simulation of two-phase flow dominated by surface tension, accurate surface tension modeling is beneficial to better reproduce and understand the mechanism of interphase flow. In this paper, based on an ISPH-FVM coupling framework, three different surface tension models are implemented and tested respectively, including the generally used continuum surface force (CSF) model, the continuous surface stress (CSS) model and the height function (HF) model. In the present ISPH-FVM coupling framework, the ISPH particle approximate interpolation technique combined with a volume fraction correction scheme is employed to ensure the volume conservation in the computational domain during the information transfer between particles and grids. Meanwhile, the three surface tension models are discretized and calculated by the volume fraction defined on the FVM grid. The volume fraction of the FVM grid is obtained by approximate interpolation of ISPH particles within the grid support domain. Several benchmark cases are tested to verify the performance of three surface tension models in the ISPH-FVM coupling method. The results show that the CSF model and CSS model have less spurious currents and better robustness than HF model under the present coupling method. In addition, the CSF model and CSS model can simulate the flow regime involving complex interface topology changes more accurately than HF model. • An ISPH-FVM coupling method is developed to simulate two-phase flows. • The volume conservation is guaranteed during the information transfer. • Three surface tension models are implemented and compared under the present coupling method. • The CSF and CSS model can get relatively small spurious currents than HF model. • The CSF and CSS model perform well in predicting the complex interface topological changes. [ABSTRACT FROM AUTHOR]

The launcher recovery method known as 'In-Air Capturing' is an innovative approach where a winged rocket stage is captured mid-air by an aircraft and subsequently towed back to the launch site. To achieve this, a capturing device attached to a tether is released from the towing aircraft. This device autonomously connects the reusable launch vehicle to the aircraft, while the two vehicles are in proximity. The tether's flexible dynamics have a strong influence on the maneuverability of the capturing device. Thus, it is critical to model the dynamics of the tether to get a realistic understanding and to evaluate feasibility of the concept. However, precise modelling and control of highly flexible systems with large deformations is both challenging and computationally intensive. For engineering applications which involve closed-loop simulations, finding a trade-off between accuracy and computational effort is crucial. In this paper, the tether is modelled as a discretized chain of rigid bodies connected by rotational springs at the joints. The tether along with the capture system is integrated in a simulation model and open loop tests are performed to analyse the system characteristics. The tether properties are studied to find a suited configuration for 'In-Air Capturing'. • Multibody modelling approach for long cable like bodies with large deformation. • Capture system dynamics for the unique 'In-Air Capturing' launcher recovery concept. • Dynamic modelling for the complete capturing system including towing aircraft, capturing device and tether. • Assessment of tether properties suited for 'In-Air Capturing' with sensitivity studies. [ABSTRACT FROM AUTHOR]

The article describes the method of synthesis of the simulation model of pulse converters with the control system, intended for implementation in FPGA. The technique is based on the structural representation of integro-differential and algebraic equations and the method of switching breaking functions. The models you develop allow you to bring modeling time closer to real. The method is described by an example of a solar battery energy conversion channel of an automatic spacecraft power supply system. The paper considers the possibility of implementing a solar-hydrogen energy supply scheme. This concept involves the accumulation of excess energy in the form of chemical energy on board the spacecraft. [ABSTRACT FROM AUTHOR]

This paper presents the high-fidelity physical modeling of a Thrust Vector Control (TVC) system operated by Electro-Mechanical Actuators (EMAs) for Reusable Launch Vehicles (RLVs). In contrast to simplified, often linear, models, high-fidelity physical models enable a better assessment of the actual system performance and a deeper verification of the on-board software robustness against disturbances, unmodeled dynamics or degradation. This aspect is essential to enable the reusability concept as driven by long-term reliability requirements. Moreover, critical systems like Fault Detection, Isolation and Recovery (FDIR) logic, whose robustness and efficacy are often difficult to prove, can be thoroughly tested without requiring hardware experiments with eventual invasive modifications for fault injections. This work captures the whole dynamics of the EMA and TVC components, including the power drive electronics, the electrical motor, and the mechanical transmission for the EMA, as well as the mechanical properties of the engine nozzle acting as a load. The resulting differential algebraic equation system is modeled in the Modelica acausal object-oriented modeling language. An ad-hoc framework is implemented to guarantee flexibility and modularity, which allows models with different fidelity levels to be easily exchanged to achieve the simulation objectives and needed accuracy level. The impact of the different models on the closed-loop TVC dynamics is analyzed in both the frequency and time domain, and then benchmarked with a realistic RLV mission. The results show that the high-fidelity physical models provide a better understanding of the more complex effects governing the TVC dynamics and can, in turn, effectively improve its requirement definition process. • The physical modeling and simulation of an EMA-based TVC system is presented. • High-fidelity physical models help assessing TVC system control software performance. • EMA component models with incremental fidelity levels are proposed. • EMA and TVC system models are integrated in a Modelica-based framework. • Different closed-loop responses are analyzed in the frequency and time domains. [ABSTRACT FROM AUTHOR]

• Two coupled parallel frameworks for shell and tube heat exchangers are proposed. • Fully three-dimensional parallel computation on both sides of the heat exchanger is realized. • One-to-one method achieves 85% parallel efficiency in 14 cores computation. • One-to-many method improves computational efficiency by about 20 times over serial in 28 cores computation. Shell and tube heat exchanger is widely used as a common type of heat exchanger. When the size and the number of heat exchanger tubes are enormous, it is difficult to use the direct modeling method for numerical simulation of heat exchangers. The simplified modeling method based on porous media utilizing user-defined function (UDF) has been widely applied. However, when the three-dimensional (3D) modeling is required on the tube side, the parallelization problem still restricts the computational efficiency of numerical simulation. In this paper, a one-to-one parallel method was first developed to solve the problem of coupled parameter transfer between the primary and secondary sides in the parallel framework, which was tested to achieve a parallel efficiency of 85% under 14 cores. However, the method acquires complicated data transfer between nodes, large memory occupation, and the modeling of the tube side is different from the actual structure under certain circumstances. To solve the problems, a one-to-many parallel method is proposed, and the computational efficiency is tested to be enhanced by about 20 times under 28 cores compared with single core, with a parallel efficiency of 70%. The two methods proposed in this paper are of great significance to the parallel transformation of the future 3D full-size code for shell and tube heat exchangers development and the calculation efficiency improvement. [ABSTRACT FROM AUTHOR]

The paper provides an overview of the radiation protection challenges and the advanced simulation techniques used to study and plan complex interventions in radiation areas at CERN, particularly with regard to the Large Hadron Collider. The operational radiation protection aspects are supported by state of the art simulations by means of the FLUKA Monte Carlo code and estimates obtained via several tools, used within the CERN Radiation Protection group, such as ActiWiz, SESAME, and the Fluence Conversion Coefficients (FCC) method which extend the built-in FLUKA capabilities. The paper covers the general Radiation Protection principles and rules in force at CERN, the simulation tools/techniques used to fulfill operational tasks and predictive studies, and a set of case studies covering relevant applications at the Large Hadron Collider machine and experiments. • Advanced and reliable simulation tools are essential in modern Radiation Protection. • FLUKA is widely used at CERN for radiation protection studies at the LHC complex. • Simulation tools such as SESAME, FCC and ActiWiz extend FLUKA built-in capabilities. • RP studies of the upgrade of the LHC are mainly based on advanced simulation tools. • Real-case applications and examples are provided in the paper. [ABSTRACT FROM AUTHOR]

A system of diffusion–reaction equations coupled with a dissolution–precipitation model is discussed in this paper. We start by introducing a microscale model together with its homogenized version. In the present paper, we first derive the corrector results to justify the obtained theoretical results. Furthermore, we perform the numerical simulations to compare the outcome of the effective (homogenized) model with the original heterogeneous microscale model. [ABSTRACT FROM AUTHOR]

• Derive trajectory and vibration equations in fractal dimension. • The designed simulation surface has self-affinity and directionality. • Reduction of Sa and Sq errors in simulation models. • The study can provide simulation data support for machine vision measurement. The grinding surface's 3-D topography has self-affinity. To more accurately simulate this characteristic, this paper proposes for the first time to construct a grinding surface simulation model based on fractional derivatives, including: utilizing the Weierstrass-Mandelbrot function to simulate the point cloud of the grinding wheel surface; further deriving the trajectory equation based on the He's fractal derivative; the semi-inverse method is employed to construct the fractional-order variational principle of the vibration equation. Experiments show that the simulation model designed in this paper can predict the surface height more accurately, and is better than the traditional model in the calculation of roughness parameters Sa and Sq. The model is helpful to thoroughly understand the formation mechanism of grinding surface topography, and provides simulation data guidance for machine vision inspection of grinding surface in micron scale. [ABSTRACT FROM AUTHOR]

Emergency response environments in which the crisis occurs include many homogenous and heterogeneous entities, e.g., organizations and persons. These entities need to collaborate to address a crisis. However, most of the time, the organizations that are involved in a crisis suffer from communication and coordination problems. This may cause unfair resource distribution. To mitigate the problem, there is a pressing need to construct models of emergency response environments and simulate the coordination strategies proactively, before the onset of any crisis. This paper highlights the complexity of the system formed by interacting organizations during a crisis and the difficulty in programming for the simulation of such complex systems. To cope with this issue, this paper presents an executable domain-specific modeling language called CoorERE. The language facilitates modeling emergency response environments for the simulation of one of the most common coordination strategies, i.e., auction-based coordination strategies in crisis response. CoorERE is used for the graphical modeling of emergency response environments and simulation of both inter and intra-organizational auction-based coordination strategies. The paper presents two case studies with different complexities to show the applicability of CoorERE. An empirical study is conducted to compare CoorERE with MDD4ABMS, which is one of the most recent tools for modeling and simulation of multi-agent systems. The evaluation includes both objective and subjective assessments. The objective assessment considers the development effort required for modeling a complete case study, while the subjective assessment compares the tools in terms of satisfying modeling method requirements and quality metrics such as usability, productivity, and expressiveness. The results of the evaluation indicate that CoorERE reduces the development effort by about 47%. In terms of quality metrics, CoorERE obtained higher scores than MDD4ABMS for all the measurements considered, indicating its superior usability, productivity, and expressiveness. [ABSTRACT FROM AUTHOR]

In this paper, we address modelling and simulation of dynamics involved in docking of large marine vessels with aid of tugboats, with the aim of providing a tool for improved design of control algorithms for autonomous docking operations. Mathematical models of the docking vessel and tugboats in 3DOF are derived, with a special focus on realistic interactions through towline, contact and friction forces with stick–slip dynamics and time delays, which are typically not considered in previous publications on the topic. We also present the implementation of the developed models in the first step towards a Simulink simulator in which considers the special case of tugboat-assisted docking operations in the Narvik harbour. The developed simulator is available on GitHub (see Ørke et al. (2023)) and encompasses model dynamics, tugboat control and vessel control and guidance, although the scope of this paper is model dynamics. We present simulation results that show that we are indeed able to capture interaction dynamics in a realistic way. Finally, we include a discussion of our results and some ideas for further development, as well as some concluding remarks. [Display omitted] • Mathematical modelling of docking vessel and tugboats in 3DOF. • Modelling of interaction forces in pushing/pulling operations. • Model implementation in Simulink-developed simulator. • Simulation and discussion of interaction forces, and ideas for future work. [ABSTRACT FROM AUTHOR]

With the widespread applications of sintered NdFeB, the impact-prone scenarios are often encountered. Such impacts will cause magnetic disorder inside the magnet and further demagnetization. At present, research on impact-induced demagnetization of sintered NdFeB mostly focuses on experimental investigations, lacking clear theoretical expressions and visual reproduction of the microscopic demagnetization process. To end this, this paper uses the impact-induced demagnetization experiment, theoretical expression, and micromagnetic simulation to reveal and quantify the demagnetization behavior of NdFeB. An impact-induced demagnetization experimental platform capable of producing corresponding load amplitudes is first established. The experimental results demonstrate the existence of reversible and irreversible demagnetization of NdFeB under impact. A magneto-mechanical constitutive model for sintered NdFeB considering stress history is further developed using the principle of thermodynamic, pinning effect and proximity effect. The residual magnetization intensity between the numerical simulation and the experimental results have good agreement. Finally, the demagnetization behavior of the magnet is visually displayed through the micromagnetic simulation. Employing the LLG equation and kinematic equations for elastic waves, a set of magnetization dynamics equations is established to analyze impact-induced demagnetization characteristics in sintered NdFeB. These results will provide the reference for the application of NdFeB in impact environment. • Carry out impact-induced demagnetization experiment of sintered NdFeB. • Obtain the magneto-mechanical constitutive demagnetization model of sintered NdFeB. • Reveal the demagnetization mechanism of sintered NdFeB by micromagnetic simulation. • Verify the constitutive model through the impact-induced demagnetization experiment and micromagnetic simulation results. [ABSTRACT FROM AUTHOR]

Sampling in control applications is increasingly done non-equidistantly in time. This includes applications in motion control, networked control, resource-aware control, and event-based control. Some of these applications, like the ones where displacement is tracked using incremental encoders, are driven by signals that are only measured when their values cross fixed thresholds in the amplitude domain. This paper introduces a non-parametric estimator of the impulse response and transfer function of continuous-time systems based on such amplitude-equidistant sampling strategy, known as Lebesgue sampling. To this end, kernel methods are developed to formulate an algorithm that adequately takes into account the bounded output uncertainty between the event timestamps, which ultimately leads to more accurate models and more efficient output sampling compared to the equidistantly-sampled kernel-based approach. The efficacy of our proposed method is demonstrated through a mass–spring damper example with encoder measurements and extensive Monte Carlo simulation studies on system benchmarks. [ABSTRACT FROM AUTHOR]

Data-driven three-dimensional (3D) mineral prospectivity modeling (MPM) employs diverse 3D exploration indicators to express geological architecture and associated characteristics in ore systems. The integration of 3D geological models with 3D computational simulation data enhances the effectiveness of 3D MPM in representing the geological architecture and its coupled geodynamic processes that govern mineralization. Despite variations in modality (i.e., data source, representation, and information abstraction levels) between geological models and simulation data, the cross-modal gap between these two types of data remains underexplored in 3D MPM. This paper presents a novel 3D MPM approach that robustly fuses multimodal information from geological models and simulation data. Acknowledging the coupled and correlated nature of geological architectures and geodynamic processes, a joint fusion strategy is employed, aligning information from both modalities by enforcing their correlation. A joint fusion neural network is devised to extract maximally correlated features from geological models and simulation data, fusing them in a cross-modality feature space. Specifically, correlation analysis (CCA) regularization is utilized to maximize the correlation between features of the two modalities, guiding the network to learn coordinated and joint fused features associated with mineralization. This results in a more effective 3D mineral prospectivity model that harnesses the strengths from both modalities for mineral exploration targeting. The proposed method is evaluated in a case study of the world-class Jiaojia gold deposit, NE China. Extensive experiments were carried out to compare the proposed method with state-of-the-art methods, methods using unimodal data, and variants without CCA regularization. Results demonstrate the superior performance of the proposed method in terms of prediction accuracy and targeting efficacy, highlighting the importance of CCA regularization in enhancing predictive power in 3D MPM. • Casting 3D mineral prospectivity modeling (MPM) as a deep multimodal fusion problem. • Joint fusion network for integrating features of 3D geological models and simulation data. • Canonical correlation analysis regularization to guide network fusion of the cross-modal gap. • Maximizing the correlation of multimodal information boosts the performance of 3D MPM. [ABSTRACT FROM AUTHOR]

Prior research lacks understanding about how collaborative arrangements and network structures influence innovation outcomes in platform-based ecosystems. This paper addresses this gap by using an NK simulation model to investigate the impacts of different collaboration patterns and network structures on innovation performance. The NK simulation approach overcomes the shortcomings of empirical methods and enables examining the dynamic impacts. The results reveal that the "special platform + generic complementor" pattern leads to the highest innovation output. The impact of component correlations on the innovation performance follows an inverted U-shape. The small world network structure promotes innovation versus regular or random networks. The results provide novel theoretical insights into strategically configuring platform partnerships and network connections to optimize innovation. The findings offer practical guidance for firms to choose beneficial collaboration pattern and design proper network structure. [ABSTRACT FROM AUTHOR]

This paper proposes 1) a new hybrid analysis technique by integrating a data-driven method with a physics-based technique to perform nonlinear analysis of steel structural systems under seismic loading, 2) two component-based data-driven models (PI-SINDy and DPI-SINDy) for predicting the nonlinear hysteretic response of steel seismic fuses with and without hysteretic degradation. The proposed hybrid data-driven and physics-based simulation (HyDPS) technique offers an efficient approach for seismic analysis of structures and is expected to address the challenges associated with computational cost and modeling uncertainties inherent in physics-based numerical simulations. In this technique, the well-understood components of the structure modeled numerically are combined with the critical components of the structure simulated using one of the data-driven models developed in this study. The proposed data-driven models were trained using experimental and numerical hysteresis data. The results show that these data-driven models can accurately and efficiently predict the nonlinear hysteretic response of steel structural components with and without degradation. Furthermore, the performance of the HyDPS technique powered by the PI-SINDy model is verified in the presence of noise using response history analyses performed on a steel buckling-restrained braced frame. • Proposed a hybrid seismic analysis technique for steel structures combining data-driven and physics-based models. • Developed two sparse regression-based data-driven models for simulating steel structures with/without degradation. • Utilized a dimensionality reduction algorithm to enhance the efficiency of the data-driven model with degradation. • Validated the data-driven models and hybrid technique with experimental and synthetic numerical data. [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]

This paper aims to improve existing models for drag, lift, and pitching torque coefficients of cylindrical disc particles with a wider range of aspect ratios and particle Reynolds numbers. The full body-fitted direct numerical simulations (DNS) are carried out for three-dimensional flow past cylindrical discs in order to quantify the coefficients at aspect ratios from 0.2 to 0.6, incidence angles from 0°to 90°, and Reynolds numbers from 0.1 to 300. The CFD results are validated against the aerodynamic coefficients of both spherical and non-spherical particles presented in the literature. A full set of new correlations for the coefficients, dependent on aspect ratio, incidence angle, and Reynolds number, is further derived according to the CFD predicted data. The results show that the new correlations have a promising performance for the disc particles considered in this study. [Display omitted] • CFD simulations are performed for drag, lift, and pitching torque coefficients. • A complete set of correlations for C D , C L , and C T is proposed. • Proposed correlations work well outside the Stokes regime. • The correlation predictions agree with the CFD simulations. [ABSTRACT FROM AUTHOR]

This paper proposes rigid-body modelling and identification procedures for long-reach dual-arm manipulators in a cable-suspended pendulum configuration. The proposed model relies on a virtually constrained open kinematic chain and lends itself to be simulated through the most commonly used robotic simulators without explicitly account for the cables constraints and flexibility. Moreover, a dynamic parameters identification procedure is devised to improve the simulation model fidelity and reduce the sim-to-real gap for controllers deployment. We show the capability of our model to handle different cable configurations and suspension mechanisms by customising it for two representative cable-suspended dual-arm manipulation systems: the LiCAS arms suspended by a drone and the CRANEbot system, featuring two Pilz arms suspended by a crane. The identified dynamic models are validated by comparing their evolution with data acquired from the real systems showing a high (between 91.3% to 99.4%) correlation of the response signals. In a comparison performed with baseline pendulum models, our model increases the simulation accuracy from 64.4% to 85.9%. The simulation environment and the related controllers are released as open-source code. • Cable-suspended long-reach manipulators perform hazardous inspection and maintenance. • Accurate simulation and control development for cable-suspended robots is crucial. • Simplified dynamic model can be readily integratable into standard simulators. • Identification procedure to reduce sim-to-real gap and develop model-based controls. [ABSTRACT FROM AUTHOR]

• A three-dimensionally mesoscale concrete was geometrically reconstructed to reflect its heterogeneity. • A mesoscale model for sulfate-induced evolution of chemo-mechanical behavior of concrete was developed. • Chemo-mechanical response of concrete from sulfate diffusion to damage failure was numerically simulated. This paper aims at numerical description on the time-varying chemo-mechanical behavior of concrete served in sulfate-rich environments. For this purpose, a three-dimensionally (3-D) mesoscale model was developed to investigate the chemo-mechanical damage evolution of concrete under external sulfate attack (ESA). Firstly, a geometrical reconstruction of 3-D concrete at meso scale was carried out to reflect its material heterogeneity, while the mechanical property of every composition in mesoscale concrete was quantitatively characterized; Secondly, the diffusion and reaction of sulfates in concrete were modelled, while its induced expansion deformation and damage evolution of CM matrix were formulated; Finally, by numerical implementation in ABAQUS, these developed models were used to numerically simulate the space–time distributions of sulfate and ettringite concentrations, expansive deformation, cracking damage, mechanical performance and failure mode of concrete, and results from numerical simulation were consistent with the experimental observations. Consequently, the developed model can describe time-varying chemo-mechanical behavior of concrete, and it is beneficial for the performance evaluation and life prediction of concrete structures in sulfate environments. [ABSTRACT FROM AUTHOR]

The aircraft assembly system is highly complex involving different stakeholders from multiple domains. The design of such a system requires comprehensive consideration of various industrial scenarios aiming to optimize key performance indicators. Traditional design methods heavily rely on domain expert knowledge using documents to define assembly solutions which are later verified through simulations. However, these document-centric approaches cannot provide graphical notations for engineers to efficiently understand the entire assembly process. Moreover, it is difficult to analyze the performance of the designed assembly processes using simulations since the simulation models have to be developed based on the documents manually rather than be generated automatically from the design models. In this paper, a semantic-driven approach is proposed to support aircraft assembly process formalism and performance analysis. First, meta-models of aircraft assembly processes are developed based on SysML and discrete-event simulation models using a semantic modeling language named KARMA. Then an application ontology is defined for generating semantic models from KARMA architecture models to capture domain knowledge, system requirements and simulation model information of the aircraft assembly process. A model transformer is developed to transform the KARMA models to discrete-event simulation models based on the application ontology. Then the generated simulation models are executed to obtain the simulation results for verifying the designed assembly process. Finally, the obtained simulation results are used to support decision-making of selecting the optimal aircraft assembly process. A case study is conducted to verify the proposed method. [ABSTRACT FROM AUTHOR]

The South African sunflower industry is considering transferring to a quality-based marketing system driven by an incentive. However, the ability of silos to offer necessary segregation services is critical in such a transition (Baker et al., 1997) and the silo industry is concerned about the negative impact segregation could have on operations and finances. This paper proposes a multi-method simulation approach to quantify the impact of quality-based segregation and sunflower farmer response to the incentive on silo bin utilisation and the ability of the silo to store contents of arriving trucks (service level). A combination of agent-based simulation, discrete event simulation and Bayesian network sampling is used to capture system behaviour where data is scarce. Therefore, in this study, a mixed methods ABM and DES model is implemented in a new environment: a grade-based segregation problem in the South African silo industry. Several scenarios are modelled to cross-validate methods and to tease out the impact of farmer response on the results. The model is applied to a case study silo complex to test the concept. Results obtained for the case study silo show a significant negative impact on costs due to lower service levels and bin utilisation, incurring relocation and opportunity costs. Overall, this study highlights that it is necessary to consider the impact that sunflower segregation could have on each unique silo complex and provides a method to quantify the stated impact. • A model is developed to analyse the impact of quality-based sunflower segregation on a silo. • An agent-based model is used to solve a silo segregation problem within a new environment: the South African context. • An expert-driven Bayesian network is used to overcome a data scarcity constraint. • For a case study silo, a 6%–11% reduction in financial performance was found relative to the base case. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic behavior of a Van der Pol oscillator (used as an archetypal self-sustained oscillator) coupled to a bistable nonlinear energy sink (BNES). We first show using numerical simulations that this system can undergo a multitude of motions including different types of periodic regimes and so-called strongly modulated responses (SMR) as well as chaotic regimes. We also show that a BNES can be much more efficient than a classical cubic NES but this is not robust since a little perturbation can switch the system from harmless to harmful situations. However, even in the most unfavorable cases, it is possible to find a set of parameters for which the BNES performs better than the NES. A multiple time scales approach is then addressed to analyze the system. In this context, we show that the so-called Multiple Scale/Harmonic Balance Method (MSHBM) must be modified (compared to its usual use) to consider the specific feature of the BNES, i.e., that it can have a nonzero-mean oscillating motion. This allows us to derive a so-called amplitude-phase modulation dynamics (APMD) which can reproduce the complex behavior of the initial system. Because of the presence of a small perturbation parameter (i.e., the mass ratio between the BNES and the VdP oscillator), the APMD is governed by two different time scales. More precisely, it appears as a (3,1)-fast–slow system whose motion is constituted in a succession of slow and fast epochs. Founding a (3,1)-fast–slow APMD is interesting since that implies a more complex dynamics than in the case of a classic NES whose APMD is only (2,1)-fast–slow. A fast–slow analysis is finally conducted within the framework of the geometric singular perturbation theory. From the computation of the so-called critical manifold and the analytical expressions of the APMD fixed points, a global stability analysis is performed. This enables us to interpret a certain number of regimes observed on numerical simulations of the initial system. • A Van der Pol oscillator is coupled to a Bistable Nonlinear Energy Sinks is studied. • The so-called MSHBM is modified to consider specific features of the BNES. • The obtained amplitude-phase modulation dynamics (APMD) is a (3,1)-fast–slow system. • Fast–slow analysis of the APMD is performed. • This enables to interpret a certain number of regimes observed on numerical simulations. [ABSTRACT FROM AUTHOR]

Blistering is a unique failure form of plate fuel elements. During the long-term operation of the plate fuel element with dispersed fuel, the phenomenon of the local blister on the cladding surface caused by the accumulation of fission gas may occur. This phenomenon will not only affect the flow and heat transfer of coolant in the blister channel but also lead to a local high void fraction on the heating wall, and make the boiling crisis occur early. The forms and distributions of blisters on the cladding surface may be various under different conditions. At present, there are few reports on the distribution of void fraction in the blister channel under subcooled boiling conditions. However, CHF, which is one of the core thermal design criteria, is closely related to the distribution of void fraction. So, in this paper, the void fraction distribution in narrow rectangular channels with different blister heights and forms was studied by using the numerical simulation method with the Euler-Euler model and the modified RPI model. The calculation results showed that the void fraction at the back end of the blister area will have a local maximum, and the backflow of fluid at the back end of the blister is the main reason for the high void fraction. In addition, as the blister height increased, the local maximum value would also increase. When the blister height exceeded 1.5 mm, the local maximum void fraction would exceed 0.82, which would lead to a localized boiling crisis on the cladding surface. Under the same blister area and blister height conditions, multiple blisters were more likely to have multiple peak void fraction points than a single pillow blister. At the same location, the peak void fraction of blisters on both sides of the heating wall was higher than that on one side, and a boiling crisis might occur on both sides of the heating wall. [ABSTRACT FROM AUTHOR]

In the early stages of health attention, such as in the examination rooms, patients are generally treated using a First In First Treat (FIFT) logic. This treatment style is inefficient from an operational view as it leads to long waiting times for critical patients. Based on optimization and discrete-event simulation, this paper introduces a hybrid model to assign patients priorities and exam rooms. Patients arrive to the system following a probability function, and for every discrete interval, a mixed-integer linear optimization model is used to allocate patients, considering health priority, preparation times, and availability of time and resources. Instances of the problem are defined using information from a health system in Mexico. Additional to the linear model, a heuristic algorithm is proposed, composed of two phases and aims to provide good, feasible, and fast solutions without ensuring optimality. Computational experiments showed that the linear model is more appropriate for small instances since the heuristic is faster and the relative deviations with respect to the linear model are below five percent. Finally, the discrete-event simulation is run for two cases: (1) with a FIFT logic and (2) using the optimization model. The hybrid model reduces the global waiting times up to 90% and the number of high health priority patients who are not treated up to 100%. • A mixed-integer linear model and a heuristic algorithm are used to allocate patients. • Optimization-simulation model reduced waiting times in primary health centers. • Optimization-simulation model reduced the number of non-treated patients. • The hybrid model is applied in a real Mexico's health system. [ABSTRACT FROM AUTHOR]

• Process informatics characteristics for crystal growth based on their differences with material informatics are discussed. • Applications of information science to crystal growth are reviewed. • Challenges and prospects informatics applications are discussed. The application of information science and technology has led to a paradigm shift in scientific and technological research and crystal growth is no exception. Various types of application research have been conducted, and research methods that combine real experiments and simulations with information techniques are becoming increasingly complex. In this paper, I focus on the application of information science and technology to the field of crystal growth. In the first half, I discuss the characteristics of process informatics, including applications to crystal growth, from the perspective of how it differs from materials informatics. In the second half, by reviewing various application studies to crystal growth, I aim to highlight the characteristics and discuss future issues. [ABSTRACT FROM AUTHOR]

The subsea capping stack is crucial equipment for emergency rescue in a blowout scenario, which determines the success or failure of the emergency rescue. The secondary risk prevention of the blowout emergency continues to face a persistent challenge. This paper proposes a methodology framework for emergency risk of the subsea capping stack, which aims to realize the quantitative risk assessment of installation operation by integrating numerical simulation and an Artificial neural network (ANN) model. Herein, the numerical model of fluid impact for the capping stack is constructed, and the impact forces of the blowout fluid are analyzed. The calculation results indicate that the blowout pressure, water depth, and installation height significantly affect the impact force during emergency operations. Furthermore, a genetic algorithm optimizing the neural network (GA-BP) model for quickly predicting the blowout impact force is established to improve emergency response efficiency based on sufficient simulation data. The prediction model has a minor mean absolute percentage error (MAPE), and its accuracy is also verified compared with the SVM model. Besides, the developed model speeds up the processing time from hours to seconds compared to numerical simulation. Therefore, it can provide a decision-making basis for emergency engineers at the site of blowout accidents more efficiently. • An integrated methodology is proposed to quantify the installation risk for the subsea capping stack. • The simulation model of the capping stack during the installation process is constructed to predict the impact forces. • A prediction model is developed to speed up the processing time from hours to seconds compared to numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper, we study a weak Galerkin (WG) finite element method for semiconductor device simulations. We consider the one-dimensional drift–diffusion (DD) and high-field (HF) models, which involves not only first derivative convection terms but also second derivative diffusion terms, as well as a coupled Poisson potential equation. The main difficulties in the analysis include the treatment of the nonlinearity and coupling of the models. The weak Galerkin finite element method adopts piecewise polynomials of degree k for the approximations of electron concentration and electric potential in the interior of elements, and piecewise polynomials of degree k + 1 for the discrete weak derivative space. The optimal order error estimates in a discrete H 1 norm and the standard L 2 norm are derived. Numerical experiments are presented to illustrate our theoretical analysis. Moreover, numerical schemes also work out for the discontinuous diffusion coefficient problems. [ABSTRACT FROM AUTHOR]

This paper presents a modeling and simulation study of dynamic compression behavior of Bulk Metallic Glasses (BMGs) at room and elevated temperatures using the split Hopkinson pressure bar (SHPB) setup. The primary objective of this study is to develop and validate a constitutive model and simulation methodology capable of predicting the high strain rate response of BMGs at different temperatures. We propose a constitutive model for BMGs that accounts for the effects of high strain rates and elevated temperatures. We numerically implemented this model in ABAQUS/Explicit Finite Element Analysis software by writing a Vectorized User Material (VUMAT) subroutine. The methodology for modeling and simulation of dynamic compression of BMG specimens using the SHPB setup is developed. The present simulations are able to correctly predict the rate-independent response of Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 (Vitreloy-1) BMG under dynamic compression at room and elevated temperatures. Furthermore, the present simulations are also able to correctly predict the negative strain rate sensitivity (SRS) of Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 (Vitreloy-105) BMG at room temperature. Finally, the present simulations correctly predict that the failure stress of Zr 64.13 Cu 15.75 Ni 10.12 Al 10 BMG decreases with increasing temperature and exhibits a minimal positive SRS. The present study is the first successful attempt to model the mechanical response of various BMGs under dynamic compression and at room and elevated temperatures. In particular, the experimentally observed negative SRS in some BMGs has been successfully simulated. The present work has important implications for the design of next generation spacecraft shields that are based on BMGs for mitigating the effects of hypervelocity impacts from debris in space. • Developed a modeling and simulation methodology for dynamic compression of BMGs using the SHPB setup • Proposed and validated a new constitutive model for BMGs for high strain rates and elevated temperatures • The rate-independent response of Vitreloy-1 BMG is correctly predicted by the model • The negative strain rate sensitivity of Vitreloy-105 BMG is accurately captured by the model • Mild positive strain rate sensitivity of Zr 64.13 Cu 15.75 Ni 10.12 Al 10 BMG at elevated temperatures is also accurately reproduced by the model [ABSTRACT FROM AUTHOR]

• A reliability-based design optimization under multiple simulation models is proposed. • An active learning function is proposed by estimating how updates on simulation model affect reliability. • A concept of activity function is proposed, which estimates how active constraint functions are. • The proposed active learning function is modified to apply to problems where the cost of each simulation model is different. • Two numerical and one engineering examples are investigated to validate the proposed method. This paper proposes an effective active learning strategy for reliability-based design optimization (RBDO) problems in which the constraint functions are acquired from multiple simulation models. To achieve this goal, a new active learning function (ALF) is derived by estimating the increased reliability of active constraint functions after adding one point to the train points of constraint functions in each simulation model. The proposed ALF distinguishes possibly active constraint functions that seem active near the current optimum and considers how the constraint functions are active. In the proposed RBDO method, a Kriging model is iteratively updated by adding the best point to the train points of constraint functions included in the crucial simulation model until the optimum converges and the Kriging model is sufficiently accurate. The best point and the crucial simulation model are obtained by comparing the proposed ALF. The ALF is further modified to apply to problems where the cost of each simulation model is different. To verify the effectiveness of the proposed method, two numerical and one engineering examples are analyzed. The results show that the proposed method efficiently and accurately obtains the RBDO optimum involving multiple simulation models, regardless of simulation cost. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle (ORC) can improve engine power by recovering exhaust energy. This paper co-optimizes the engine-ORC combined system's power and NOx emission, with decision variables of the engine's excess air ratio, spark advance angle, as well as ORC's pump and expander speeds. Firstly, a simulation model of the combined system is established and validated. Then, the initial dataset is generated by the D-optimum Latin hypercube method and simulation model. The artificial neural network (ANN) prediction models of NOx emission and power are established based on these datasets. Finally, the co-optimization is conducted using the ANN prediction model and genetic algorithm. Focusing on maximizing the combined system's power results in an 18.30 % increase in power, and a significant reduction in brake-specific fuel consumption (BSFC) and brake-specific NOx (BSNOx) by 10.10 % and 71.30 %, respectively, compared to the unoptimized basis. Targeting the lowest BSNOx leads to a limited 1.20 % increase in power output; however, it results in a 19.50 % increase in BSFC. When optimizing for both system output and BSNOx, the output remains 13.5 % above the unoptimized basis. Meanwhile, up to 89.8 % of BSNOx can be eliminated with negligible deterioration in BSFC. This study could be used for engine performance enhancements. • A data-driven ANN prediction model of engine-ORC combined system is established. • ANN cooperates with GA to co-optimize Combined system's power and NOx emission. • The optimum engine and ORC parameters for the different goals are obtained. [ABSTRACT FROM AUTHOR]

• A novel Coordinated Cyber-Physical Attacking (CCPA) mode on power grids. • Full malicious power dispatch based on false command injection by maximizing inverse-community characteristic as objective to quantify vulnerability of the system. • Partial malicious power dispatch as the measure in CCPA. • Demonstration of the proposed novel CCPA mode. This paper proposes a new mode of cyber-physical attack based on injecting false commands, which poses an increasing risk to modern power systems as a typical example of Cyber-Physical Systems (CPS). Such attacks can trigger physical attacks by driving the system into vulnerable states. To address the critical issues arising from this new mode, we define an inverse-community (IC) in power flow distribution and evaluate it using inverse-modularity. To identify the most vulnerable state of the IC that represents the inherent vulnerability of the system, we employ a full malicious power dispatch problem. We also analyze an example of the proposed mode, where a partial malicious power dispatch that maximizes inverse-modularity is combined with physical attacks aimed at disconnecting vulnerable IC boundary lines, making cascading failures highly likely. To demonstrate the potential impact of this coordinated cyber-physical attack, we use the IEEE-118 and IEEE-300 bus systems for simulation. The results show the effectiveness of this attack strategy and provide a new perspective to analyze cyber-physical security issues in modern power systems. [ABSTRACT FROM AUTHOR]

The train platforming problem is one of the most investigated topics in the train operation field. However, a systematic understanding of how train platforming improves the convenience of passenger transfer procedures is still lacking. To face the rapidly growing transfer demands in the high-speed railway station, this paper proposes a transfer-facilitating-oriented train platforming approach based on a multi-agent train operation simulation model. By evaluating the transfer connection quality using an indicator named Transfer Connection Strength(TCS), which considers transfer distance and transfer time, the proposed transfer-facilitating-oriented train platforming strategies can establish more convenient transfer connections and so improve the transfer service. A track occupation horizon based on the modelling of accurate train running processes is utilized to detect route conflicts and guarantee conflict-free train operations in the simulation model, enabling the solutions' feasibility of train platforming to be taken into account. A series of simulation experiments are conducted using real data of Zhengzhou East station in China. The experiment results show that, the proposed transfer-facilitating-oriented train platforming strategies are capable of obtaining a greater number of convenient transfer connections. The feasibility can be guaranteed by permitted train delays and route conflict detection for the succeeding trains in a forward-looking period. Additionally, the platform assignment plans can be generated with a specified priority of transfer distance or transfer time. [ABSTRACT FROM AUTHOR]

This paper presents the reference architecture of a model for sustainable local planning and sector coupling based on an energy-community framework. The proposed approach includes four building blocks: (1) the data-acquisition building block - local energy consumption, (2) the building block for modelling and calculations - local energy conversions, (3) the building block for connecting the infrastructure status and needs with development plans of the energy-network operators and aggregators, and (4) the decision-support building block for local environmental, spatial and energy planning. The proposed approach was tested in a real industrial environment and a local community. Initial simulation results confirmed that excess heat from the energy-intensive company has the potential to replace the natural gas that is currently used for the production of heat in a local district-heating system. The natural gas savings in the district-heating system would be 3,299,676 Nm3, as the excess heat could cover as much as 68.4 % of the required heat for the local community. It has also been proven that complex modelling and simulation of a future sustainable solution can contribute to its optimization, understanding, and acceptance by all stakeholders and thereby increase the potential of the project's implementation. • Concept of the reference architecture of an energy community model is proposed. • The proposed concept enables a systematic sustainable local planning. • Utilization of the excess heat from the energy intensive company is presented. • The main challenge is the appropriate involvement of all relevant stakeholders. [ABSTRACT FROM AUTHOR]

In this paper, the synthesis and gamma-radiation shielding attributes of xMgO-(30-x)BaO-69.5B 2 O 3 -0.5Fe 2 O 3 glasses are reported. The aim is to ascertain the optimum chemical structure of the glass system for gamma radiation shielding applications and dosimetry. The simple melt and quench method was adopted for the synthesis of the xMgO-(30-x)BaO-69.5B 2 O 3 -0.5Fe 2 O 3 glasses, where for x = 0, 5, 10, 12, and 15 mol% represented MBBFe-0, MBBFe-1, MBBFe-2, MBBFe-3, and MBBFe-4, respectively. The mass attenuation coefficients μ / ρ of the glasses were evaluated using the XCOM and FLUKA simulations for the photon energy range of 15 keV–15 MeV. The differences between the values of μ / ρ evaluated with FLUKA and XCOM were within 0.96%. The mass attenuation coefficients of MBBFe-0, MBBFe-1, MBBFe-2, MBBFe-3, and MBBFe-4 ranged from 0.0288 to 28.6205 cm2/g, 0.0279–25.6462 cm2/g, 0.0268–22.2712 cm2/g, 0.0260–20.4073 cm2/g and 0.0251–18.4086 cm2/g, respectively. The corresponding values of the half-value layer at 15 MeV are 7.06 cm, 7.64 cm, 8.25 cm, 8.70 cm, and 9.53 cm for MBBFe-0, MBBFe-1, MBBFe-2, MBBFe-3, and MBBFe-4, respectively. The specific gamma constant values of MBBFe-X glasses are in the range 11.289–264.417 Rm2/Cihr, 10.871–236.716 Rm2/Cihr, 10.386–205.282 Rm2/Cihr, 9.931–187.921 Rm2/Cihr and 9.444–175.515 Rm2/Cihr for MBBFe-0, MBBFe-1, MBBFe-2, MBBFe-3, and MBBFe-4, respectively. The substitution of BaO with MgO therefore, depreciated the gamma shielding efficacy, photon energy absorption abilities, and interaction per unit mass of the MBBFe-X glasses. This study concludes that MBBFe-0 is the best gamma absorber among the studied glasses and has the potential to be a good gamma-radiation shield with an efficiency that supersedes many traditional and modern shielding materials such as concrete, metal alloys, polymers, rocks, commercial glass shields, and other shielding glasses. • New glassy system are reported for radiation uses. • Gamma shielding performance is studied for the new system. • Monte Carlo simulations are carried out. • A good agreement between the theory and the simulation. • MBBFe-X has a potential use in shielding applications. [ABSTRACT FROM AUTHOR]

Previous seismic studies have mostly focused on standalone equipment and single-span coupling systems in electrical substations. To fully consider the impact of adjacent equipment, this paper proposed and validated a motion equations-based numerical solution method for seismic responses of multi-span flexible conductor-post equipment coupling systems (CPECSs). Based on this, the influence of equipment frequency, sag-to-span ratio, peak ground acceleration, and equipment number on seismic responses of multi-span CPECSs was investigated. Finally, the equipment range that significantly influences the seismic response of a piece of equipment was studied, thus the concept of seismic correlation segment was further proposed, beyond which the equipment can be ignored in terms of its influence on seismic responses. The results indicate that the proposed numerical method exhibits enough accuracy based on the validation by simulation techniques. The influencing laws of various interconnection factors on seismic responses of equipment provide support for seismic design of substations. Moreover, the seismic correlation segment can be obtained by presetting the response ratio of a piece of equipment in multi-span to single-span systems, not only reducing the number of concerned equipment but also maintaining the calculation accuracy. • A motion equations-based solution method for seismic responses of multi-span CPECSs was proposed and validated. • Four critical influence factors on seismic responses of multi-span CPECSs were investigated. • Equipment range that significantly influences seismic responses of a piece of equipment was studied and determined. • The concept of seismic correlation segment of multi-span CPECSs was presented. [ABSTRACT FROM AUTHOR]

As mentioned in Part 1, for product iterative design, the digital simulation method, as the product performance analysis method, has the problems of time cost and computing resources. To address this issue, a product performance rapid simulation approach driven by digital twin (DT) data for variable product structures in Part 1 was proposed, which could replace the digital simulation method. Meanwhile, for performance analysis under variable operating conditions during the product design and operation phase, digital simulation also has the above problems. Therefore, based on the method for variable product structures proposed in Part 1, a product performance rapid simulation approach driven by DT data for variable operating conditions is proposed in this paper. Firstly, the framework for variable operating conditions is designed based on the makeTwin reference architecture, including twin source data acquisition for the product under different operating conditions, twin data-driven product performance rapid simulation model (RSM) construction for variable operating conditions, and rapid evaluation of product critical performance based on RSM. Then, the implementation of the framework is introduced in detail. At last, a case study for critical loosening load evaluation of bolted joint is carried out. The result indicates that the proposed method is feasible, as well as costs shorter simulation time than the traditional digital simulation method. [ABSTRACT FROM AUTHOR]