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For a few years the multi-physics modelling of the resonance cavity (resonator) of MW-class continuous-wave gyrotrons, to be employed for electron cyclotron heating and current drive in magnetic confinement fusion machines, has gained increasing interest. The rising target power of the gyrotrons, which drives progressively higher Ohmic losses to be removed from the resonator, together with the need for limiting the resonator deformation as much as possible, has put more emphasis on the thermal-hydraulic and thermo-mechanic modeling of the cavity. To cope with that, a multi-physics simulator has been developed in recent years in a shared effort between several European institutions (the Karlsruher Institut für Technologie and Politecnico di Torino, supported by Fusion for Energy). In this paper the current status of the tool calibration and validation is addressed, aiming at highlighting where any direct or indirect comparisons with experimental data are missing and suggesting a possible roadmap to fill that gap, taking advantage of forthcoming tests in Europe.

Multi-physical contact behaviour is important in multiple disciplines related to the automotive industry. Nowadays battery-electric vehicles' (BEV) thermal management systems deal with contact between bodies where mechanical, electric, and thermal interaction occurs. The battery thermal management itself is crucial for cell life, safety, and everyday vehicle performance. Thus, comprehensive and accurate simulation of the multi-physical contact is a vital part of vehicle development. The multi-physical contact is represented by two or more bodies under applied mechanical load and a current or heat conducted throughout the realized contact area. The amount of conducted current/heat or generated Joule heat is the function of the contact area as well as contact pressure, thus the structural simulation should be essential for such thermal management system simulations Most of the current full vehicle battery pack CFD cooling simulations simplified the multi-physical contact as ideal. Detailed contact modelling is time-consuming, hence not applicable for the full vehicle modelling. In this work, a feasible approach based on contact resistance curves was implemented. Furthermore, the work demonstrates the necessity of correct structural contact prediction for a joule heating and thermal solution.

The contact morphology change caused by high-current ablation will seriously affect the electric field distribution in the interrupter chamber, which in turn affects the closing prebreakdown arc duration, indicating that the prebreakdown arc duration can be used as one of the indicators to measure the contact ablation state. A circuit breaker simulated ablation test platform was established, and the voltage and current signals, electromagnetic field signals, and vibration signals in the process of circuit breaker closing were measured, and the closing prebreakdown duration was calculated. The results show that under the same size of the ablation current, with the ablation of the contacts, the closing prebreakdown duration shows an overall trend of increasing and then decreasing, and the larger the ablation current is, the larger the change in the closing prebreakdown duration is. At the same time, simulation verification was carried out, and the results show that the electric field distortion on the surface of the static arc contact inside the arc extinguishing chamber is the largest, and the ablation of the contact will further increase the degree of distortion of the electric field inside the arc extinguishing chamber. As the degree of ablation increases, the prebreakdown moment of the circuit breaker closing is advanced, and the prebreakdown duration increases.

The mechanisms underlying reduced deformability of red blood cells (RBCs) in Plasmodium falciparum remain unclear. The decrease in RBC deformability associated with malarial infection was measured using ektacytometry, and only mean values were evaluated. In this study, we report the development of a microfluidic sensing device that can evaluate decreased RBC deformability at the single-cell level by measuring ionic current waveforms through micropores. Using an in vitro culture system, we found that when RBC deformability was reduced by P. falciparum infection, ionic current waveforms changed. As RBC deformability decreased, waveforms became asymmetric. Computer simulations suggested that these waveform parameters are largely independent of RBC size and may represent a reliable indicator of diminished deformability. This novel microfluidic RBC deformability sensor allows for detailed single-cell analysis of malaria-associated deformability reduction, potentially aiding in elucidating its pathology.

Laser and electrochemical machining (LECM) is extensively researched due to its high efficiency and good surface quality. Laser and shaped tube electrochemical machining (Laser-STEM) is a novel hybrid process, in which both the laser beam and electrolyte jet are guided to the machining zone through the inner hole of a specially designed tubular electrode. This process could be utilized to process small holes with a larger depth and a higher controlled precision, compared with the existing LECM processes. In Laser-STEM, the direct laser processing and the enhanced electrochemical machining (ECM) rate allow the high-efficiency material removal. ECM that is synchronously occurred in the side gap guarantees the high surface quality of the processed small holes. Through the total internal reflection of the laser beam in the inner hole of the tubular electrode, the laser energy is transmitted to the machining zone in high efficiency, and the laser energy has been confined in the inner hole exit area. Theoretical and experimental results showed that the electric current density in the machining zone for ECM could be increased by the assistance of a laser, which enhances the material removal rate of ECM. With the self-developed experimental setup, microcavities with a depth of 2 mm and small holes with a depth of 5 mm have been fabricated. A comparison of the effects of various machining parameters shows that the machining precision and material removal rate were improved by 60.7% and 122.7%, respectively. Both the machining precision and the material removal rate could be increased by using higher laser power. The mechanisms of machining precision improvement by adopting laser to STEM were explored, considering the generation of the passivating layer in the machining zone. Laser-STEM was also adopted to fabricating three-dimensional structures such as groove and channel.

High-fidelity simulations of turbulent flames are computationally expensive when using detailed chemical kinetics. For practical fuels and flow configurations, chemical kinetics can account for the vast majority of the computational time due to the highly non-linear nature of multi-step chemistry mechanisms and the inherent stiffness of combustion chemistry. While reducing this cost has been a key focus area in combustion modeling, the recent growth in graphics processing units (GPUs) that offer very fast arithmetic processing, combined with the development of highly optimized libraries for artificial neural networks used in machine learning, provides a unique pathway for acceleration. The goal of this paper is to recast Arrhenius kinetics as a neural network using matrix-based formulations. Unlike ANNs that rely on data, this formulation does not require training and exactly represents the chemistry mechanism. More specifically, connections between the exact matrix equations for kinetics and traditional artificial neural network layers are used to enable the usage of GPU-optimized linear algebra libraries without the need for modeling. Regarding GPU performance, speedup and saturation behaviors are assessed for several chemical mechanisms of varying complexity. The performance analysis is based on trends for absolute compute times and throughput for the various arithmetic operations encountered during the source term computation. The goals are ultimately to provide insights into how the source term calculations scale with the reaction mechanism complexity, which types of reactions benefit the GPU formulations most, and how to exploit the matrix-based formulations to provide optimal speedup for large mechanisms by using sparsity properties. Overall, the GPU performance for the species source term evaluations reveals many informative trends with regards to the effect of cell number on device saturation and speedup. Most importantly, it is shown that the matrix-based method enables highly efficient GPU performance across the board, achieving near-peak performance in saturated regimes.

Purpose This study aims to optimize the manufacturing process to improve the manufacturing quality, costs and delivering time with the help of multiscale multiphysics modelling and simulation. Multiscale multiphysics-based modelling and simulations are receiving more and more interest by research community and the industry particularly in the context of increasing demands for manufacturing high precision complex products and understanding the intrinsic complexity in associated manufacturing processes. Design/methodology/approach In this paper, some modelling and analysis techniques using multiscale multiphysics modelling are presented and discussed. Findings Furthermore, the possibility of adopting the multiscale multiphysics modelling and simulation to develop the virtual machining system is evaluated, and further supported with an industrial case study on abrasive flow machining (AFM) of integrally bladed rotors using the techniques and system developed. Originality/value With the development of multiscale multiphysics-based modelling and simulation, it will enable effective and efficient optimisation of manufacturing processes and further improvement of manufacturing quality, costs, delivery time and the overall competitiveness.

Recent and strict regulations in the maritime sector regarding exhaust gas emissions has led to an evolution of shipboard systems with a progressive increase of complexity, from the early utilization of electric propulsion to the realization of an integrated shipboard power system organized as a microgrid. Therefore, novel approaches, such as the model-based design, start to be experimented by industries to obtain multiphysics models able to study the impact of different designing solutions. In this context, this paper illustrates in detail the development of a multiphysics simulation framework, able to mimic the behaviour of a DC electric ship equipped with electric propulsion, rotating generators and battery energy storage systems. The simulation platform has been realized within the retrofitting project of a Ro-Ro Pax vessel, to size components and to validate control strategies before the system commissioning. It has been implemented on the Opal-RT simulator, as the core component of the future research infrastructure of the University of Genoa, which will include power converters, storage systems, and a ship bridge simulator. The proposed model includes the propulsion plant, characterized by propellers and ship dynamics, and the entire shipboard power system. Each component has been detailed together with its own regulators, such as the automatic voltage regulator of synchronous generators, the torque control of permanent magnet synchronous motors and the current control loop of power converters. The paper illustrates also details concerning the practical deployment of the proposed models within the real-time simulator, in order to share the computational effort among the available processor cores.

The two-dimensional GTAW arc model is insufficient to fully explain the effects of the external longitudinal magnetic field on the arc. Therefore, a three-dimensional GTAW arc model was established to elucidate the recirculation flow and negative pressure arc characteristic of magnetic-controlled arc. The external magnetic field controls the surface temperature, pressure, and current density distribution of the workpiece by controlling the flow of arc plasma. When the magnetic flux density is 0.04T, the surface temperature, pressure, and current density of the workpiece exhibit a bimodal distribution. Under the negative pressure of the GTAW arc, the arc plasma on both sides flowed counterclockwise around the center in the spiral upward direction and then counterclockwise downward from 0.9 mm below the tungsten electrode. By controlling the welding current and magnetic flux density, the occurrence of negative surface pressure on the workpiece can be effectively controlled.

Nowadays, urban rail transit is expanding towards high-elevation zones, and the effect of the low air pressure environment on the pantograph-catenary system is becoming increasingly prominent. As a key indicator for evaluating the electrical contact performance of a pantograph-catenary system, research on the electrical characteristics of the pantograph-catenary arc is of great significance. For this reason, this paper established a plasma mathematical model applicable to the arc of the urban rail transit bow network based on the theory of magnetohydrodynamics. The mathematical model of the pantograph-catenary arc was used to set the relevant initial conditions. Based on COMSOL Multiphysics finite element simulation software, this study developed a multi-physics simulation model of the pantograph-catenary arc and systematically analysed its voltage characteristics and current density distribution under varying air pressure conditions. The results showed that as the air pressure decreases, the potential at the axial points declines, the pressure drop across the arc poles becomes more pronounced, and the current density decreases accordingly. This study provides theoretical and technical support for optimizing the design of and promoting the sustainable development of urban rail transit pantograph-catenary systems in high-altitude areas.