Articoli di riviste: "MAXWELL 3D SIMULATION"

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Rong-yan, Guo, e Shi Shui-e. "AC Contactor Electromagnetic Mechanism Dynamic Simulation Study". Open Electrical & Electronic Engineering Journal 8, n. 1 (31 dicembre 2014): 419–27. http://dx.doi.org/10.2174/1874129001408010419.

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In this paper, we study the application of Maxwell 3D and ADAMS software for simulation and analysis of electromagnetic system, with UG software for AC contactor and main contact system of electromagnetic system. We then study the influence of harmonic on type CJX2-40 AC contactor main contact system and operation characteristics. To establish a three-dimensional finite element model of electromagnetic mechanism of AC contactor, we take Maxwell 3D software, on the model of finite element mesh, the calculation of different closing sine excitation and containing under harmonic excitation angle electromagnetic system. For the static and dynamic characteristics of AC contactor, static magnetic field distribution and the suction characteristic curve drawing, we do a comparative study of the results of the simulation, analysis of the influence of harmonics on the AC contactor motion characteristics.

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Ganse, Urs, Tuomas Koskela, Markus Battarbee, Yann Pfau-Kempf, Konstantinos Papadakis, Markku Alho, Maarja Bussov et al. "Enabling technology for global 3D + 3V hybrid-Vlasov simulations of near-Earth space". Physics of Plasmas 30, n. 4 (aprile 2023): 042902. http://dx.doi.org/10.1063/5.0134387.

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We present methods and algorithms that allow the Vlasiator code to run global, three-dimensional hybrid-Vlasov simulations of Earth's entire magnetosphere. The key ingredients that make Vlasov simulations at magnetospheric scales possible are the sparse velocity space implementation and spatial adaptive mesh refinement. We outline the algorithmic improvement of the semi-Lagrangian solver for six-dimensional phase space quantities, discuss the coupling of Vlasov and Maxwell equations' solvers in a refined mesh, and provide performance figures from simulation test runs that demonstrate the scalability of this simulation system to full magnetospheric runs.

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Zhang, Guang Cai, Hong Fu Ai, Ya Jie Xu, Qiao Yan Chen e Xiao Dong Yang. "The Design of Small H-Style Permanent Magnet Used for NMR". Applied Mechanics and Materials 703 (dicembre 2014): 114–18. http://dx.doi.org/10.4028/www.scientific.net/amm.703.114.

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This paper introduces the design of permanent magnet that can been used to small nuclear magnetic resonance (NMR) system, and its static magnetic field simulation analysis uses Ansoft's Maxwell software. According to the theory of magnetic circuit design and the performance requirements of magnetic field, An H-style permanent magnetic actuator has been designed, and it can generate uniform magnetic field larger than 0.4 T in the interested region of this actuator. The static magnetic field simulation analysis of this permanent magnetic actuator has done by Ansoft's Maxwell 3D software, and the experimental results show that the design of permanent magnet can meet the requirements.

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Chen, Keyu, Marcus Hartwig e Shahram Amoozegar. "Electric machine noise and vibration prediction and validation through test". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 264, n. 1 (24 giugno 2022): 309–16. http://dx.doi.org/10.3397/nc-2022-735.

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In this paper, a finite element (FE) simulation process for the NVH prediction of electric motors is proposed. The proposed process first simulates the motor excitation forces using a 2D electromagnetic force model which is derived from Maxwell and then it applies these forces to a simplified 3D electric machine model. This simplified 3D model is validated by comparing the structural transfer functions calculated from impact hammer test and FE simulation. Finally, the proposed simulation process is validated by comparing predicted sound pressure levels at different selected locations to an electric motor NVH test results from a semi-anechoic chamber.

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Peng, Wen Zhen, Shu Min Wan, Bin Lin, Li Peng Sun e Mei Ning Yang. "Finite Element Simulation of Electromagnetic Properties of Ferrite Material". Materials Science Forum 770 (ottobre 2013): 29–33. http://dx.doi.org/10.4028/www.scientific.net/msf.770.29.

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As the inductance of magnetic cores is the most important parameter for their service performance. Four coupling models of EE-type ferrite cores are established to analyze the relationship between surface quality and the inductance of ferrite cores. Besides, 3D FEM simulation of different models is made by ANSOFT MAXWELL software. The results show that the surface quality has a direct influence on the service performance of ferrite devices.

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Song, Shou Xiang, Liang Zou, Tong Zhao, Li Zhang, Qing Quan Li e Meng Qi Liu. "FEM Simulations of Permanent-Magnet-Biased Saturation Based Fault Current Limiter". Advanced Materials Research 960-961 (giugno 2014): 867–70. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.867.

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The fault current limit technology based on the principle of permanent-magnet-biased saturation has several outstanding advantages in both economy and technology. A modeling method of PMFCL based on the finite element analysis platform – Maxwell is presented in this paper. The current limiting mechanism of line-type PMFCL is analyzed, on the basis of which the 2D and 3D models are established in Maxwell, and the corresponding experiments are designed as well. Comparisons between the simulation and experimental results indicate that the modeling method is reasonable. Research achievements of this paper provides theoretical basis for further studies of PMFCL.

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Du, Lin, Geng Chen Shi e Jing Jing Zhao. "Static Characteristics of Micro Disc Magneto Electric Generator – Simulation and Experiment". Applied Mechanics and Materials 365-366 (agosto 2013): 356–59. http://dx.doi.org/10.4028/www.scientific.net/amm.365-366.356.

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Maxwell 3D software of finite-element analysis in electromagnetic fields is used to model and simulate the micro disc magneto electric generator. Distribution characteristics of magnetic induction are required and theoretical analysis and calculation is presented. Error between the simulation result and experimental result is about 6% which verify the rationality and accuracy of finite-element simulation. It can be used to guide the structural design and optimization of this type of generator.

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Blome, Mark, Kevin McPeak, Sven Burger, Frank Schmidt e David Norris. "Back-reflector design in thin-film silicon solar cells by rigorous 3D light propagation modeling". COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, n. 4 (1 luglio 2014): 1282–95. http://dx.doi.org/10.1108/compel-12-2012-0367.

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Purpose – The purpose of this paper is to find an optimized thin-film amorphous silicon solar cell design by numerically optimizing the light trapping efficiency of a pyramid-structured back-reflector using a frequency-domain finite element Maxwell solver. For this purpose short circuit current densities and absorption spectra within the investigated solar cell model are systematically analyzed. Furthermore, the authors employ a topology simulation method to accurately predict the material layer interfaces within the investigated solar cell model. The method simulates the chemical vapor deposition (CVD) process that is typically used to fabricate thin-film solar cells by combining a ballistic transport and reaction model (BTRM) with a level-set method in an iterative approach. Predicted solar cell models are far more realistic compared to solar cell models created assuming conformal material growth. The purpose of the topology simulation method is to increase the accuracy of thin-film solar cell models in order to facilitate highly accurate simulation results in solar cell design optimizations. Design/methodology/approach – The authors perform numeric optimizations using a frequency domain finite element Maxwell solver. Topology simulations are carried out using a BTRM combined with a level-set method in an iterative fashion. Findings – The simulation results reveal that the employed pyramid structured back-reflectors effectively increase the light path in the absorber mainly by exciting photonic waveguide modes. In using the optimization approach, the authors have identified solar cell models with cell periodicities around 480 nm and pyramid base widths around 450 nm to yield the highest short circuit current densities. Compared to equivalent solar cell models with flat back-reflectors, computed short circuit current densities are significantly increased. Furthermore, the paper finds that the solar cell models computed using the topology simulation approach represent a far more realistic approximation to a real solar cell stack compared to solar cell models computed by a conformal material growth assumption. Research limitations/implications – So far in the topology simulation approach the authors assume CVD as the material deposition process for all material layers. However, during the fabrication process sputtering (i.e. physical vapor deposition) will be employed for the Al:ZnO and ITO layers. In the framework of this ongoing research project the authors will extend the topology simulation approach to take the different material deposition processes into account. The differences in predicted material interfaces will presumably be only minor compared to the results shown here and certainly be insignificant relative to the differences the authors observe for solar cell models computed assuming conformal material growth. Originality/value – The authors systematically investigate and optimize the light trapping efficiency of a pyramid nano-structured back-reflector using rigorous electromagnetic field computations with a 3D finite element Maxwell solver. To the authors’ knowledge such an investigation has not been carried out yet in the solar cell research literature. The topology simulation approach (to the best of the authors’ knowledge) has previously not been applied to the modelling of solar cells. Typically a conformal layer growth assumption is used instead.

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Tang, Hao, Dongpo Wang e Zhao Duan. "New Maxwell Creep Model Based on Fractional and Elastic-Plastic Elements". Advances in Civil Engineering 2020 (10 febbraio 2020): 1–11. http://dx.doi.org/10.1155/2020/9170706.

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Creep models are mainly used to describe the rheological behaviour of geotechnical materials. An important research focus for studying creep in geotechnical materials is the development of a model with few parameters and good simulation performance. Hence, in this study, by replacing the Newtonian dashpot and spring in the classical Maxwell model with fractional and elastic-plastic elements, a new Maxwell creep model based on fractional derivatives and continuum damage mechanics was developed. One- and three-dimensional (1D/3D) creep equations of the new Maxwell creep model were derived. The 1D creep equation of the new model was used to fit existing creep data of rock salt, and the 3D creep equation was used to fit the creep data of remolded loess. The model curves matched the creep data very well, showing considerably higher accuracy than other models. Furthermore, a sensitivity study was carried out, showing the effects of the fractional derivative order β and exponent α on the creep strain of rock salt. This new model is simple with few parameters and can effectively simulate the complete creep behaviour of geotechnical materials.

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Su, Yu, Le Gong, Hui Cao e Dan Dan Chen. "Optimization of Electrostatic Atomization Cutting Using 3D FE Simulation of Electrostatic Field". Key Engineering Materials 693 (maggio 2016): 1255–62. http://dx.doi.org/10.4028/www.scientific.net/kem.693.1255.

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Compared with minimal quantity lubrication (MQL), electrostatic atomization can control the movement of mist droplets by changing the electrostatic field, thus reducing the drift of mist droplets in air. This paper first proposes the concept of electrostatic atomization cutting, and then develops a 3D FE model of electrostatic field for electrostatic atomization cutting using a commercial software Ansoft Maxwell. By simulation, the influence of nozzle angle, structure, and electrode gap and voltage on electric field intensity is investigated. Based on simulation results, the optimal nozzle angle and structure are obtained for electrostatic atomization cutting. The findings contribute to further development of this technique.

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Santos, J. M., E. Ricardo, F. J. da Silva, T. Ribeiro, S. Heuraux e A. Silva. "A 3D CAD model input pipeline for REFMUL3 full-wave FDTD 3D simulator". Journal of Instrumentation 16, n. 11 (1 novembre 2021): C11013. http://dx.doi.org/10.1088/1748-0221/16/11/c11013.

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Abstract The use of advanced simulation has become increasingly more important in the planning, design, and assessment phases of future fusion plasma diagnostics, and in the interpretation of experimental data from existing ones. The design cycle of complex reflectometry systems, such as the ones being planned for next generation machines (IDTT and DEMO), relies heavily on the results produced by synthetic diagnostics, used for system performance evaluation and prediction, both crucial in the design process decision making. These synthetic diagnostics need realistic representations of all system components to incorporate the main effects that shape their behavior. Some of the most important elements that are required to be well modelled and integrated in simulations are the wave launcher structures, such as the waveguides, tapers, and antennas, as well as the vessel wall structures and access to the plasma. The latter are of paramount importance and are often neglected in this type of studies. Faithfully modelling them is not an easy task, especially in 3D simulations. The procedure herein proposed consists in using CAD models of a given machine, together with parameterizable models of the launcher, to produce a description suited for Finite Difference Time Domain (FDTD) 3D simulation, combining the capabilities of real-world CAD design with the power of simulation. However, CAD model geometric descriptions are incompatible with the ones used by standard FDTD codes. CAD software usually outputs models in a tessellated mesh while FDTD simulators use Volumetric Pixel (VOXEL) descriptions. To solve this interface problem, we implemented a pipeline to automatically convert complex CAD models of tokamak vessel components and wave launcher structures to the VOXEL input required by REFMUL3, a full wave 3D Maxwell FDTD parallel code. To illustrate the full procedure, a complex reflectometry synthetic diagnostic for IDTT was setup, converted and simulated. This setup includes 3 antennas recessed into the vessel wall, for thermal protection, one for transmission and reception, and two just for reception.

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Ressler, S. M. "3D MHD simulation of a pulsationally driven MRI decretion disc". Monthly Notices of the Royal Astronomical Society 508, n. 4 (9 ottobre 2021): 4887–901. http://dx.doi.org/10.1093/mnras/stab2880.

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ABSTRACT We explore the pulsationally driven orbital mass ejection mechanism for Be star disc formation using isothermal, 3D magnetohydrodynamic (MHD) and hydrodynamic simulations. Non-radial pulsations are added to a star rotating at 95 per cent of critical as an inner boundary condition that feeds gas into the domain. In MHD, the initial magnetic field within the star is weak. The hydrodynamics simulation has limited angular momentum transport, resulting in repeating cycles of mass accumulation into a rotationally supported disc at small radii followed by fall-back on to the star. The MHD simulation, conversely, has efficient (Maxwell αM ∼ 0.04) angular momentum transport provided by both turbulent and coherent magnetic fields: a slowly decreting midplane driven by the magnetorotational instability and a supersonic wind on the surface of the disc driven by global magnetic torques. The angle and time-averaged properties near the midplane agree reasonably well with a 1D viscous decretion disc model with a modified $\tilde{\alpha }=0.5$, in which the gas transitions from a subsonic thin disc to a supersonic spherical wind at the critical point. 1D models, however, cannot capture the multiphase decretion/angular structure seen in our simulations. Our results demonstrate that, at least under certain conditions, non-radial pulsations on the surface of a rapidly rotating, weakly magnetised star can drive a Keplerian disc with the basic properties of the viscous decretion disc paradigm, albeit coupled to a laminar wind away from the midplane. Future modelling of Be star discs should consider the possible existence of such a surface wind.

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Szulborski, Michał, Sebastian Łapczyński e Łukasz Kolimas. "Thermal Analysis of Heat Distribution in Busbars during Rated Current Flow in Low-Voltage Industrial Switchgear". Energies 14, n. 9 (24 aprile 2021): 2427. http://dx.doi.org/10.3390/en14092427.

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The manuscript presents advanced coupled analysis: Maxwell 3D, Transient Thermal and Fluent CFD, at the time of a rated current occurring on the main busbars in the low-voltage switchgear. The simulations were procured in order to aid the design process of such enclosures. The analysis presented the rated current flow in the switchgear busbars, which allowed determining their temperature values. The main assumption of the simulation was measurements of temperature rise during rated current conditions. Simulating such conditions is a valuable asset in order to design better solutions for energy distribution gear. The simulation model was a precise representation of the actual prototype of the switchgear. Simulations results were validated by experimental research. The heat dissipation in busbars and switchgear housing through air convection was presented. The temperature distribution for the insulators in the rail bridge made of fireproof material was considered: halogen-free polyester. The results obtained during the simulation allowed for a detailed analysis of switchgear design and proper conclusions in practical and theoretical aspects. That helped in introducing structural changes in the prepared prototype of the switchgear at the design and construction stages. Deep analysis of the simulation results allowed for the development concerning the final prototype of the switchgear, which could be subjected to the full type tests. Additionally, short-circuit current simulations were procured and presented.

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ÖZÜPAK, Yıldırım. "Performing Structural Design and Modeling of Transformers Using ANSYS-Maxwell". Brilliant Engineering 2, n. 2 (29 gennaio 2021): 38–42. http://dx.doi.org/10.36937/ben.2021.002.005.

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Transformers have attracted great interest since they have been used due to their robustness and application in power systems. Therefore, the nominal values of transformers grow even more in larger power systems due to the constantly increasing power demand. Many types of research are carried out to increase the performance characteristics of transformers and their compatibility with power systems. There are different methods and analysis tools for these studies. One of them is ANSYS@Maxwell, which performs analysis based on the Finite Element Method (FEM). With this program, the design, modeling, analysis, and performance evaluation of the transformer in a high-performance simulation environment can be achieved through effective strategic modeling. In this study, the design and modeling of a three-phase core-type transformer with coils and terminals are explained in detail in ANSYS @ Maxwell simulation platform. Besides, the transformer models examined were adapted using ANSYS@MAXWELL software based on the finite element method. Analyzes are performed to estimate the core-losses, leak-losses, DC-losses, and winding-eddy current losses-of transformers with this program. A large number of meshes were used in FEM analysis of 2D and 3D models to examine the losses in detail.

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Dzyurkevich, Natalia, Mario Flock e Hubert Klahr. "3D global MHD simulations of a proto-planetary disk: dead zone and large-scale magnetic fields". Proceedings of the International Astronomical Union 4, S259 (novembre 2008): 117–18. http://dx.doi.org/10.1017/s1743921309030257.

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AbstractWe present 3D global MHD simulations of proto-planetary disks calculated with the ZeusMP code. We focus on gas dynamics; the magnetic diffusivity and temperature are fixed during the simulation. A zone with low gas ionization at the midplane is included within ±2 scale heights. We mimic the ‘snow’-line radius with one order of magnitude jump in magnetic diffusivity η. Resulting turbulent Maxwell and Reynolds stresses are present at the midplane despite of low ionization. We find no radial inhomogeneities in turbulent α stress for a mild ionization contrast at the ‘snow’-line. A smooth azimuthal magnetic field is produced in the dead zone which may be a driving force for a weak accretion flow.

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Li, Jiaqi, e Shilong Jin. "Magnetic Field Analysis of Rectangular Current-carrying Coil Based on ANSOFT Maxwell 3D Simulation". Journal of Physics: Conference Series 1168 (febbraio 2019): 052020. http://dx.doi.org/10.1088/1742-6596/1168/5/052020.

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Cao, Yunbai, e Chanwoo Kim. "Glassey-Strauss representation of Vlasov-Maxwell systems in a Half Space". Kinetic and Related Models 15, n. 3 (2022): 385. http://dx.doi.org/10.3934/krm.2021034.

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<p style='text-indent:20px;'>Following closely the classical works [<xref ref-type="bibr" rid="b5">5</xref>]-[<xref ref-type="bibr" rid="b7">7</xref>] by Glassey, Strauss, and Schaeffer, we present a version of the Glassey-Strauss representation for the Vlasov-Maxwell systems in a 3D half space when the boundary is the perfect conductor.</p>

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Wang, Da Yang, Fang Yao e Zhi Gang Li. "Influence of Eddy Current Effect on the Circuit Breaker Contact Mechanism Heat Loss". Advanced Materials Research 805-806 (settembre 2013): 943–47. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.943.

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With the three-dimensional field analysis software Ansoft Maxwell 3D, the three-dimensional finite element model of the contacts pair is established. They belong to a kind of miniature circuit breaker. The simulation is carried out in the transient magnetic field. Under the condition with or without eddy current effect, we get the position and numerical solution of the contact mechanism heat loss under different short-circuit current.

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Ji, Yanju, Xiangdong Meng, Weimin Huang, Yanqi Wu e Gang Li. "3D Numerical Modeling of Induced-Polarization Grounded Electrical-Source Airborne Transient Electromagnetic Response Based on the Fictitious Wave Field Methods". Applied Sciences 10, n. 3 (4 febbraio 2020): 1027. http://dx.doi.org/10.3390/app10031027.

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The grounded electrical-source airborne transient electromagnetic (GREATEM) system is widely used in mineral exploration. Meanwhile, the induced polarization (IP) effect, which indicates the polarizability of the earth, is often found. In this paper, the Maxwell equations in the frequency domain are transformed into fictitious wave domain, where Maxwell equations are solved by the time domain finite difference method. Then, an integral transformation method is used to convert the calculation results back to the time domain. A three-dimensional (3D) numerical simulation in a polarizable medium is presented. The accuracy of this method is proven by comparing it with the analytical solution and the existing method, and the calculation efficiency is increased five-fold. The simulation results show that the GREATEM system has a higher response amplitude in the conductive region, while IP effects cannot be identified in the conductive area. The GREATEM system has a higher response amplitude in the low-resistance region, but IP effects cannot be identified in the low-resistance area, and the detection of IP effects is more suitable for the high-resistance area. Therefore, it is necessary to improve the detection ability of the GREATEM system in the low-resistance area.

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Assous, Franck, e Eric Sonnendrücker. "Joly–Mercier boundary condition for the finite element solution of 3D Maxwell equations". Mathematical and Computer Modelling 51, n. 7-8 (aprile 2010): 935–43. http://dx.doi.org/10.1016/j.mcm.2009.08.027.

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Maggiore, Nicola. "Conserved chiral currents on the boundary of 3D Maxwell theory". Journal of Physics A: Mathematical and Theoretical 52, n. 11 (15 febbraio 2019): 115401. http://dx.doi.org/10.1088/1751-8121/ab045a.

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Bai, Peixian, e Yixuan Jia. "Simulation analysis of internal and external faults in transformer area". MATEC Web of Conferences 382 (2023): 01041. http://dx.doi.org/10.1051/matecconf/202338201041.

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Under different types of internal and external faults of transformers, electrical quantities such as voltage, differential current and transformer oil flow rate change accordingly. In this paper, the variation law is studied, and the variation law of differential current and other electrical quantities under different types of faults and abnormal conditions inside and outside the transformer area is verified by simulation. The characteristics of faults inside and outside the area are different, and the faults inside and outside the transformer area are judged. At the same time, ANSYS Maxwell 3D, ANSYS Fluent and other software are used to model and simulate the transformer, and the oil flow rate changes under different operating conditions such as normal operation, external fault and internal fault of the transformer are analyzed.

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Gündoğar, Umut Yusuf, e Sibel Zorlu Partal. "Design, 3D FEM Simulation and Prototyping of a Permanent Magnet Spherical Motor". Actuators 10, n. 11 (21 novembre 2021): 305. http://dx.doi.org/10.3390/act10110305.

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In recent years, large tilt angles, uniform magnetic flux distributions, strong forces, and large torques for motors have increasingly become important for robotics, biomedical, and automotive applications that have multi-degrees of freedom (MDOFs) motion. Generally, one-degree of-freedom motors are applied in MDOF motion. These situations cause the systems to have very complex and large structures. In order to address these issues, a 2-DOF surface permanent magnet spherical motor with a new mechanical design for the movement of the rotor with a large tilt angle of ±45° was designed, simulated, produced and tested in this paper. The motor consisted of a 4-pole permanent magnet rotor and a 3-block stator with 18 coils. In this study, the mechanical structure of the proposed spherical permanent magnet motor surrounded the rotor with two moving parts to move at a large tilt angle of ±45° without using any mechanical components such as spherical bearings, joint bearings, and bearing covers. Thus, the tilt angle, force, and torque values of the proposed motor have been improved according to MDOF motion motors using spherical bearings, bearing covers, or joint bearings in their mechanical structures in the literature. Ansys Maxwell software was used for the design and simulation of the motor. Three-dimensional (3D) finite element method (FEM) analysis and experimental studies were carried out on the force, torque, and magnetic flux density distribution of the motor. Then, simulation results and experimental results were compared to validate the 3D FEM simulations results.

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WOO, BYUNG-CHUL, DO-KWAN HONG e JI-YOUNG LEE. "VARIATION OF ELECTRIC PROPERTIES BETWEEN SURFACE PERMANENT MAGNET AND INTERIOR PERMANENT MAGNET MOTOR". International Journal of Modern Physics: Conference Series 06 (gennaio 2012): 109–14. http://dx.doi.org/10.1142/s2010194512003029.

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The most distinctive advantage of transverse flux motor(TFM) is high torque density which has prompted many researches into studying various design variants. TFM is well suited for low speed direct drive applications due to its high torque density. This paper deals with simulation based comparisons between a surface permanent magnet transverse flux motor(SPM-TFM) and an interior permanent magnet transverse flux motor(IPM-TFM). A commercial finite element analysis(FEA) software Maxwell 3D is used for electromagnetic field computation to fully analyze complex geometry of the TFMs. General characteristics, such as cogging torque, rated torque and torque ripple characteristics of the two TFMs are analyzed and compared by extensive 3D FEA.

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Hamiaz, Adnane, Xavier Ferrieres e Olivier Pascal. "Efficient numerical algorithm to simulate a 3D coupled Maxwell–plasma problem". Mathematics and Computers in Simulation 174 (agosto 2020): 19–31. http://dx.doi.org/10.1016/j.matcom.2020.02.018.

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Naseri, Mahyar, Sascha C. Iden e Wolfgang Durner. "Effective hydraulic properties of 3D virtual stony soils identified by inverse modeling". SOIL 8, n. 1 (9 febbraio 2022): 99–112. http://dx.doi.org/10.5194/soil-8-99-2022.

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Abstract. Stony soils that have a considerable amount of rock fragments (RFs) are widespread around the world. However, experiments to determine the effective soil hydraulic properties (SHPs) of stony soils, i.e., the water retention curve (WRC) and hydraulic conductivity curve (HCC), are challenging. Installation of measurement devices and sensors in these soils is difficult, and the data are less reliable because of their high local heterogeneity. Therefore, effective properties of stony soils especially under unsaturated hydraulic conditions are still not well understood. An alternative approach to evaluate the SHPs of these systems with internal structural heterogeneity is numerical simulation. We used the Hydrus 2D/3D software to create virtual stony soils in 3D and simulate water flow for different volumetric fractions of RFs, f. Stony soils with different values of f from 11 % to 37 % were created by placing impermeable spheres as RFs in a sandy loam soil. Time series of local pressure heads at various depths, mean water contents, and fluxes across the upper boundary were generated in a virtual evaporation experiment. Additionally, a multistep unit-gradient simulation was applied to determine effective values of hydraulic conductivity near saturation up to pF=2. The generated data were evaluated by inverse modeling, assuming a homogeneous system, and the effective hydraulic properties were identified. The effective properties were compared with predictions from available scaling models of SHPs for different values of f. Our results showed that scaling the WRC of the background soil based on only the value of f gives acceptable results in the case of impermeable RFs. However, the reduction in conductivity could not be simply scaled by the value of f. Predictions were highly improved by applying the Novák, Maxwell, and GEM models to scale the HCC. The Maxwell model matched the numerically identified HCC best.

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Morvarid, Masoud, Ali Rezghi, Alireza Riasi e Mojtaba Haghighi Yazdi. "3D numerical simulation of laminar water hammer considering pipe wall viscoelasticity and the arbitrary Lagrangian-Eulerian method". World Journal of Engineering 15, n. 2 (9 aprile 2018): 298–305. http://dx.doi.org/10.1108/wje-08-2017-0236.

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Purpose Analysis of fast transient flow in water pipe systems is an important issue for the prevention of unfavorable pressure oscillations and severe damage to the pipelines. This paper aims to present the performance of three-dimensional (3D) simulation of laminar water hammer caused by fast closure of valve. Design/methodology/approach The viscoelastic behavior of pipe wall is mathematically modeled by using the rheological model of Maxwell. The arbitrary Lagrangian–Eulerian (ALE) method is also used to simulate fluid–structure interaction. In this method, unlike the classical water hammer theory, the acoustic wave velocity is calculated during the numerical simulations and therefore it is not predetermined. Findings Investigating the velocity profiles and the shear stress diagrams for transient flow in elastic pipe showed that the strong effect of viscous forces on the near wall region in conjunction with the influence of inertial forces in the central region of the pipe leads to creation of reverse flow near the pipe wall. Comparing the numerical results obtained for elastic pipe with those of viscoelastic pipe revealed that during transient condition, the viscoelastic wall absorbs the energy of fluid and therefore pressure fluctuations of viscoelastic pipe are damped more quickly. Moreover, the 3D simulation of water hammer confirmed the plane wave hypothesis of water hammer. Originality/value The 3D Navier–Stokes equations are solved considering the viscoelasticity of the pipe and the ALE method using the software package of COMSOL Multiphysics.

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Posenato Garcia, Artur, e Zoya Heidari. "Numerical modeling of multifrequency complex dielectric permittivity dispersion of sedimentary rocks". GEOPHYSICS 86, n. 4 (10 giugno 2021): MR179—MR190. http://dx.doi.org/10.1190/geo2020-0444.1.

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The dielectric response of rocks results from electric double layer (EDL), Maxwell-Wagner (MW), and dipolar polarizations. The EDL polarization is a function of solid-fluid interfaces, pore water, and pore geometry. MW and dipolar polarizations are functions of charge accumulation at the interface between materials with contrasting impedances and the volumetric concentration of its constituents, respectively. However, conventional interpretation of dielectric measurements only accounts for volumetric concentrations of rock components and their permittivities, not interfacial properties such as wettability. Numerical simulations of the dielectric response of rocks provide an ideal framework to quantify the impact of wettability and water saturation ([Formula: see text]) on electric polarization mechanisms. Therefore, we have developed a numerical simulation method to compute pore-scale dielectric dispersion effects in the interval from 100 Hz to 1 GHz including effects of pore structure, [Formula: see text], and wettability on permittivity measurements. We solve the quasielectrostatic Maxwell’s equations in 3D pore-scale rock images in the frequency domain using the finite-volume method. Then, we verify simulation results for a spherical material by comparing to the corresponding analytical solution. Additionally, we introduce a technique to incorporate [Formula: see text]-polarization to the simulation and we verify it by comparing pore-scale simulation results to experimental measurements on a Berea sandstone sample. Finally, we quantify the impact of [Formula: see text] and wettability on broadband dielectric permittivity measurements through pore-scale numerical simulations. The numerical simulation results show that mixed-wet rocks are more sensitive than water-wet rocks to changes in [Formula: see text] at sub-MHz frequencies. Furthermore, permittivity and conductivity of mixed-wet rocks have weaker and stronger dispersive behaviors, respectively, when compared to water-wet rocks. Finally, numerical simulations indicate that conductivity of mixed-wet rocks can vary by three orders of magnitude from 100 Hz to 1 GHz. Therefore, Archie’s equation calibrated at the wrong frequency could lead to water saturation errors of up to 73%.

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Lăzureanu, Cristian. "The Real-Valued Maxwell–Bloch Equations with Controls: From a Hamilton–Poisson System to a Chaotic One". International Journal of Bifurcation and Chaos 27, n. 09 (agosto 2017): 1750143. http://dx.doi.org/10.1142/s0218127417501437.

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Applying parametric controls to the 3D real-valued Maxwell–Bloch equations, we obtain a Hamilton–Poisson system, a dissipative system with chaotic behavior, and a transitional system between the aforementioned states, which is a conservative system that has only one constant of motion. In the Hamiltonian case, we present some connections of the energy-Casimir mapping with the equilibrium states and the existence of the homoclinic orbits. We study the stability of the equilibrium points of the transitional system and the dissipative system. Furthermore, we point out the chaotic behavior of the introduced system.

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Zhu, Li Yun, Jin Gang Wang, Yu Yi Fan e Yun Jie Bai. "The Simulation of Distribution Parameter of the Three-Phase D-Dot Voltage Sensor". Applied Mechanics and Materials 556-562 (maggio 2014): 2123–27. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.2123.

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As an electric coupling sensor, the D-dot voltage sensor can achieve non contact measurement of voltage. With the advantages of simple structure, a high dynamic range and measurement bandwidth, it can meet the needs of accurate measurement[1][2]. Thus it has great application prospects in voltage on-line monitoring, relay protection or other fields in the power system. This paper considered the operation of the three-phase lines, and established the D-dot voltage sensor simulation model in the simulation platform of Ansoft Maxwell 3D. With the simulation of the sensor working conditions, we can get the distributed parameters of the system under three-phase lines in operation, construct an equivalent circuit of measurement and analyze the simulation results to get a voltage signal of input and output. The simulation results show that, with the equivalent circuit simulation of the three-phase D-dot voltage sensor, if we improve electrode capacitance parameter, there will be a good linear relationship between the input and output.

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Krakowska, Paulina, e Paweł Madejski. "Research on Fluid Flow and Permeability in Low Porous Rock Sample Using Laboratory and Computational Techniques". Energies 12, n. 24 (9 dicembre 2019): 4684. http://dx.doi.org/10.3390/en12244684.

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The paper presents results of fluid flow simulation in tight rock being potentially gas-bearing formation. Core samples are under careful investigation because of the high cost of production from the well. Numerical simulations allow determining absolute permeability based on computed X-ray tomography images of the rock sample. Computational fluid dynamics (CFD) give the opportunity to use the partial slip Maxwell model for permeability calculations. A detailed 3D geometrical model of the pore space was the input data. These 3D models of the pore space were extracted from the rock sample using highly specialized software poROSE (poROus materials examination SoftwarE, AGH University of Science and Technology, Kraków, Poland), which is the product of close cooperation of petroleum science and industry. The changes in mass flow depended on the pressure difference, and the tangential momentum accommodation coefficient was delivered and used in further quantitative analysis. The results of fluid flow simulations were combined with laboratory measurement results using a gas permeameter. It appeared that for the established parameters and proper fluid flow model (partial slip model, Tangential Momentum Accommodation Coefficient (TMAC), volumetric flow rate values), the obtained absolute permeability was similar to the permeability from the core test analysis.

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Varma, Vishnu, e Bernhard Müller. "3D simulations of oxygen shell burning with and without magnetic fields". Monthly Notices of the Royal Astronomical Society 504, n. 1 (26 marzo 2021): 636–47. http://dx.doi.org/10.1093/mnras/stab883.

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ABSTRACT We present a first 3D magnetohydrodynamic (MHD) simulation of convective oxygen and neon shell burning in a non-rotating $18\, \mathrm{M}_\odot$ star shortly before core collapse to study the generation of magnetic fields in supernova progenitors. We also run a purely hydrodynamic control simulation to gauge the impact of the magnetic fields on the convective flow and on convective boundary mixing. After about 17 convective turnover times, the magnetic field is approaching saturation levels in the oxygen shell with an average field strength of $\mathord {\sim }10^{10}\, \mathrm{G}$, and does not reach kinetic equipartition. The field remains dominated by small-to-medium scales, and the dipole field strength at the base of the oxygen shell is only $10^{9}\, \mathrm{G}$. The angle-averaged diagonal components of the Maxwell stress tensor mirror those of the Reynolds stress tensor, but are about one order of magnitude smaller. The shear flow at the oxygen–neon shell interface creates relatively strong fields parallel to the convective boundary, which noticeably inhibit the turbulent entrainment of neon into the oxygen shell. The reduced ingestion of neon lowers the nuclear energy generation rate in the oxygen shell and thereby slightly slows down the convective flow. Aside from this indirect effect, we find that magnetic fields do not appreciably alter the flow inside the oxygen shell. We discuss the implications of our results for the subsequent core-collapse supernova and stress the need for longer simulations, resolution studies, and an investigation of non-ideal effects for a better understanding of magnetic fields in supernova progenitors.

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Zaslavsky, M., V. Druskin e L. Knizhnerman. "Solution of 3D time-domain electromagnetic problems using optimal subspace projection". GEOPHYSICS 76, n. 6 (1 novembre 2011): F339—F351. http://dx.doi.org/10.1190/geo2011-0088.1.

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Time-domain problems for controlled-source electromagnetic exploration require accurate discretization of the solution for multiple spacial and temporal scales. Therefore, forward simulation using conventional computational methods becomes computationally expensive, even without accounting for induced-polarization (IP) effects. These effects create another complication caused by the presence of a convolution integral in the time-domain Maxwell system. We suggested a novel, fast, and robust algorithm to solve the 3D time-domain electromagnetic (EM) problems that can be considered as a generalization of the spectral Lanczos decomposition method. The new method also allowed us to incorporate the IP effects without significant cost increase. The discretized large-scale Maxwell system was projected onto a small subspace consisting of the Laplace-domain solutions (the so-called parameter-dependent Krylov subspace) for an optimally chosen set of Laplace parameters. The projected system preserved stability and passivity of the original problem. Moreover, our approach (even without the IP effects) yielded an optimal solution within a wide class of computational algorithms that included the conventional time-domain finite-difference, discrete Fourier transform and spectral Lanczos decomposition methods. Numerical examples for the controlled-source EM problem showed that the new algorithm produces accurate solutions on time intervals spanning from milliseconds to hundreds of seconds with the cost of (at most) 60 time steps of the implicit finite-difference time domain scheme. This showed significant improvement even compared with results for nonpolarized media reported in recent literature. Additionally, the new algorithm had the unique capability to accurately handle large-scale 3D models, including the IP effects.

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sci, global. "Energy Identities and Stability Analysis of the Yee Scheme for 3D Maxwell Equations". Numerical Mathematics: Theory, Methods and Applications 13, n. 3 (giugno 2020): 788–813. http://dx.doi.org/10.4208/nmtma.oa-2019-0121.

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35

Khan, Najeeb Alam, Sidra Khan e Fatima Riaz. "3D stagnation point flow of Maxwell fluid towards an off-centered rotating disk". Multidiscipline Modeling in Materials and Structures 12, n. 2 (8 agosto 2016): 345–61. http://dx.doi.org/10.1108/mmms-09-2015-0058.

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Purpose – The purpose of this paper is to study the three dimensional, steady and incompressible flow of non-Newtonian rate type Maxwell fluid, for stagnation point flow toward an off-centered rotating disk. Design/methodology/approach – The governing partial differential equations are transformed to a system of non-linear ordinary differential equations by conventional similarity transformations. The non-perturbation technique, homotopy analysis method (HAM) is employed for the computation of solutions. And, the solution is computed by using the well-known software Mathematica 10. Findings – The effects of rotational parameter and Deborah number on radial, azimuthal and induced velocity functions are investigated. The results are presented in graphical form. The convergence control parameter is also plotted for velocity profiles. The comparison with the previous results is also tabulated. The skin friction coefficients are also computed for different values of Deborah number. Originality/value – This paper studies the effect of rotation and Deborah number on off-centered rotating disk has been observed and presented graphically.

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Rochlitz, Raphael, Nico Skibbe e Thomas Günther. "custEM: Customizable finite-element simulation of complex controlled-source electromagnetic data". GEOPHYSICS 84, n. 2 (1 marzo 2019): F17—F33. http://dx.doi.org/10.1190/geo2018-0208.1.

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We have developed the open-source toolbox custEM (customizable electromagnetic modeling) for the simulation of complex 3D controlled-source electromagnetic (CSEM) problems. It is based on the open-source finite-element library FEniCS, which supports tetrahedral meshes, multiprocessing, higher order polynomials, and anisotropy. We use multiple finite-element approaches to solve the time-harmonic Maxwell equations, which are based on total or secondary electric field and gauged potential formulations. In addition, we develop a secondary magnetic field formulation, showing superior performance if only magnetic fields are required. Using Nédélec basis functions, we robustly incorporate the current density on the edges of the mesh for the total field formulations. The latter enable modeling of CSEM problems taking topography into account. We evaluate semianalytical 1D layered-earth solutions with the pyhed library, supporting arbitrary configurations of dipole or loop sources for secondary field calculations. All system matrices have been modified to be symmetric and solved in parallel with the direct solver MUMPS. Aside from the finite-element kernel, mesh generation, interpolation, and visualization modules have been implemented to simplify and automate the modeling workflow. We prove the capability of custEM, including validation against analytic-solutions, crossvalidation of all implemented approaches, and results for a model with 3D topography with four examples. The object-oriented implementation allows for customizable modifications and additions or to use only submodules designed for special tasks, such as mesh generation or matrix assembly. Therefore, the toolbox is suitable for crossvalidation with other codes and as the basis for developing 3D inversion routines.

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Boubaker, Mohamed Bader, Benjamin Le Corre, Yves Meshaka e Gérard Jeandel. "Finite element simulation of the slumping process of a glass plate using 3D generalized viscoelastic Maxwell model". Journal of Non-Crystalline Solids 405 (dicembre 2014): 45–54. http://dx.doi.org/10.1016/j.jnoncrysol.2014.08.018.

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38

Nechaev, O. V., E. P. Shurina e M. A. Botchev. "Multilevel iterative solvers for the edge finite element solution of the 3D Maxwell equation". Computers & Mathematics with Applications 55, n. 10 (maggio 2008): 2346–62. http://dx.doi.org/10.1016/j.camwa.2007.11.003.

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39

Mauro, G. S., G. Torrisi, A. Pidatella, A. Galatá e D. Mascali. "Numerical Design of RF Antennas for Ion Cyclotron Resonance Heating in ECRIS Environment". Journal of Physics: Conference Series 2244, n. 1 (1 aprile 2022): 012023. http://dx.doi.org/10.1088/1742-6596/2244/1/012023.

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Abstract In this paper we present the numerical design and simulation of RF antennas to be employed in Ion Cyclotron Resonance Heating (ICRH) systems working in ECRIS environment. A 3D full-wave numerical model, based on the coupling between COMSOL FEM solution of Maxwell equations and the MATLAB-computed non-homogeneous plasma dielectric tensor, has been employed in order to study the performances of several ICRH antennas. Results in terms of S-parameters, on-axis electric field and RF absorbed power inside the plasma chamber have been obtained and compared between the chosen antenna geometries. The presented study will permit to better understand the fundamental aspects of ion dynamics in ECRISs as well as allowing the design of a proper matching network between the RF amplifier and the antenna, necessary to cope with the plasma properties’ fast variations. Further ion kinetic simulations are ongoing.

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Mauro, G. S., G. Torrisi, A. Pidatella, A. Galatá e D. Mascali. "Numerical Design of RF Antennas for Ion Cyclotron Resonance Heating in ECRIS Environment". Journal of Physics: Conference Series 2244, n. 1 (1 aprile 2022): 012023. http://dx.doi.org/10.1088/1742-6596/2244/1/012023.

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Abstract (sommario):

Abstract In this paper we present the numerical design and simulation of RF antennas to be employed in Ion Cyclotron Resonance Heating (ICRH) systems working in ECRIS environment. A 3D full-wave numerical model, based on the coupling between COMSOL FEM solution of Maxwell equations and the MATLAB-computed non-homogeneous plasma dielectric tensor, has been employed in order to study the performances of several ICRH antennas. Results in terms of S-parameters, on-axis electric field and RF absorbed power inside the plasma chamber have been obtained and compared between the chosen antenna geometries. The presented study will permit to better understand the fundamental aspects of ion dynamics in ECRISs as well as allowing the design of a proper matching network between the RF amplifier and the antenna, necessary to cope with the plasma properties’ fast variations. Further ion kinetic simulations are ongoing.

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Assous, Franck, e Irina Raichik. "A NUMERICAL METHOD FOR 3D TIME-DEPENDENT MAXWELL’S EQUATIONS IN AXISYMMETRIC SINGULAR DOMAINS WITH ARBITRARY DATA". Mathematical Modelling and Analysis 28, n. 3 (4 settembre 2023): 487–508. http://dx.doi.org/10.3846/mma.2023.17553.

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In this article, we propose to solve the three-dimensional time-dependent Maxwell equations in a singular axisymmetric domain with arbitrary data. Due to the axisymmetric assumption, the singular computational domain boils down to a subset of R2. However, the electromagnetic field and other vector quantities still belong to R3. Taking advantage that the domain is transformed into a two-dimensional one, by doing Fourier analysis in the third dimension, one arrives to a sequence of singular problems set in a 2D domain. The mathematical tools of such problems have been exposed in [4,19]. Here, we derive a variational method from which we propose an original finite element numerical approach to solve the problem. Numerical experiments are also shown to illustrate that the method is able to capture the singular part of the solution. This approach can also be viewed as a generalization of the Singular Complement Method to three-dimensional problem.

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Al-Jubori, Waleed Khalid Shakir, e Yasir Abdulhafedh Ahmed. "Study and analysis the effect of variable applied voltage on SCIM performances based on FEA". International Journal of Power Electronics and Drive Systems (IJPEDS) 11, n. 3 (1 settembre 2020): 1230. http://dx.doi.org/10.11591/ijpeds.v11.i3.pp1230-1240.

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Study and analysis the effect of variable applied voltage on SCIM performances based on FEA is presented. Three phase squirrel cage induction motor SCIM has been investigated and numerically simulated using finite element method (FEM) with the aid of ANSYS software (RMxprt and Maxwell 2D/3D). This research presents study and analysis of the effects of the voltage variation on performance and efficiency of the three-phase induction motor of the squirrel cage type. The Finite Elements Analysis Method FEA is used as one of the best methods for analysis and simulation of electrical motors in addition to the possibility of dealing with nonlinear equations, Since the induction motor is a complex electromagnetic reaction, the researchers used the ANSYS program to represent and analyze the performance of the motor under variable supply voltage. The case studied in this research is three phases, 380V, 50Hz, 2.2kW, induction motor that widely use in industrial application. The aim of this research is to study the effect of voltage variation on efficiency, current value, power factor and torque of SCIM. The RMxprt software has been used for modeling and simulating the induction motor and calculating the values of phases currents, input and output power in additional of overall efficiency at steady state condition. The next stage of the research is creating Maxwell 2-D design from the base model of RMxprt software, Maxwell 2-D model has the ability to computing the distribution of magnetic field and explaining the performance under steady-state operation. The obtained results show significant reduction of motor performance due to the effect of variation of apply voltage.

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Fiore, P. V., D. B. Maghous e A. Campos Filho. "A tridimensional finite element approach to model a tunnel with shotcrete and precast concrete". Revista IBRACON de Estruturas e Materiais 9, n. 3 (giugno 2016): 403–13. http://dx.doi.org/10.1590/s1983-41952016000300005.

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ABSTRACT This paper describes a numerical simulation with 3D finite elements of a tunnel. The viscoplastic law of Perzyna represents the rockmass behavior. The concrete, shotcrete or precast, is modeled as a viscoelastic material through the Maxwell and Kelvin chain models. Finite element simulations are performed by incorporating subroutines for viscoelastic concrete models in the ANSYS code. The method to simulate tunnel excavations is by activating and deactivating elements in sequential steps. In the first part of the paper two validations are performed. The analytical solution and the deformation achieved on the stabilization in the ANSYS code are compared with an unlined tunnel. A lined tunnel, with an elastic and viscoplastic rockmass combined with an elastic lining, is compared with the results of the GEOMEC91 code. In the second part, it is compared the same tunnel with two different concrete lining for two chain models. Finally, it is modeled the Kielder experimental tunnel, which in situ measured data is available.

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Wojciechowski, Rafał M. "Analysis and optimisation of an axial flux permanent magnet coreless motor based on the field model using the superposition principle and genetic algorithm". Archives of Electrical Engineering 65, n. 3 (1 settembre 2016): 601–11. http://dx.doi.org/10.1515/aee-2016-0043.

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Abstract In the paper, methodologies for the magnetic field simulation in an axial flux permanent magnet coreless (AFPMC) motor have been proposed and discussed. Two approaches have been considered and investigated, both based on representing the 3D field distribution by superimposing axisymmetric 2D patterns. The first of studied approaches applies directly to the Biot-Savart law while the second uses a 2D axisymmetric finite element method. The selected results of magnetic field distributions and electromagnetic torque characteristics for the considered AFPMC motor have been presented and compared with results obtained using the commercial FEM package ‘Maxwell’. The elaborated algorithms have been incorporated into the design routines allowing multi-parameter optimisation of the considered motor construction.

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Egea-Lopez, Esteban, Jose Maria Molina-Garcia-Pardo, Martine Lienard e Pierre Degauque. "Opal: An open source ray-tracing propagation simulator for electromagnetic characterization". PLOS ONE 16, n. 11 (17 novembre 2021): e0260060. http://dx.doi.org/10.1371/journal.pone.0260060.

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Accurate characterization and simulation of electromagnetic propagation can be obtained by ray-tracing methods, which are based on a high frequency approximation to the Maxwell equations and describe the propagating field as a set of propagating rays, reflecting, diffracting and scattering over environment elements. However, this approach has been usually too computationally costly to be used in large and dynamic scenarios, but this situation is changing thanks the increasing availability of efficient ray-tracing libraries for graphical processing units. In this paper we present Opal, an electromagnetic propagation simulation tool implemented with ray-tracing on graphical processing units, which is part of the Veneris framework. Opal can be used as a stand-alone ray-tracing simulator, but its main strength lies in its integration with the game engine, which allows to generate customized 3D environments quickly and intuitively. We describe its most relevant features and provide implementation details, highlighting the different simulation types it supports and its extension possibilites. We provide application examples and validate the simulation on demanding scenarios, such as tunnels, where we compare the results with theoretical solutions and further discuss the tradeoffs between the simulation types and its performance.

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Chen, Na, Yan Song Wang, Hui Guo, Jie Lei e Tao Zhang. "A Study on Static Features of a High-Speed Solenoid Valve Used in Diesel Engine". Applied Mechanics and Materials 189 (luglio 2012): 393–97. http://dx.doi.org/10.4028/www.scientific.net/amm.189.393.

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Based on the Maxwell equation and simulation analysis method, this paper investigates and retains the optimized parameters of a high-speed solenoid valve, which is very important for electrical unit pump (EUP) diesels. According to the electromagnetic theory, firstly, a three-dimensional (3D) model of the solenoid valve is established, and working process of the electromagnets is analyzed by using both the theoretical method and Ansys Workbench software. In view of the electromagnetic force, furthermore, several parameters related to the solenoid valve performance are considered and their effects on solenoid valve are analyzed and discussed. Finally, the optimized parameters are proposed for the analyzed solenoid valve and proved by theoretical equations. The studied approach can be extended to any other field related to the electromagnetic device design.

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Lampadariou, Eleftheria, Konstantinos Kaklamanis, Dimitrios Goustouridis, Ioannis Raptis e Elefterios Lidorikis. "Nonlocal Effective Medium (NLEM) for Quantitative Modelling of Nanoroughness in Spectroscopic Reflectance". Photonics 9, n. 7 (16 luglio 2022): 499. http://dx.doi.org/10.3390/photonics9070499.

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Spectroscopic reflectance is a versatile optical methodology for the characterization of transparent and semi-transparent thin films in terms of thickness and refractive index. The Fresnel equations are used to interpret the measurements, but their accuracy is limited when surface roughness is present. Nanoroughness can be modelled through a discretized multi-slice and effective medium approach, but to date, this offered mostly qualitative and not quantitative accuracy. Here we introduce an adaptive and nonlocal effective medium approach, which considers the relative size and environment of each discretized slice. We develop our model using finite-difference time-domain simulation results and demonstrate its ability to predict nanoroughness size and shape with relative errors < 3% in a variety of test systems. The accuracy of the model is directly compared to the prediction capabilities of the Bruggeman and Maxwell–Garnett models, highlighting its superiority. Our model is fully parametrized and ready to use for exploring the effects of roughness on reflectance without the need for costly 3D simulations and to be integrated into the Fresnel simulator of spectroscopic reflectance tools.

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Ghnatios, Chady, Anais Barasinski e Francisco Chinesta. "On the High-Resolution Discretization of the Maxwell Equations in a Composite Tape and the Heating Effects Induced by the Dielectric Losses". Computation 10, n. 2 (29 gennaio 2022): 24. http://dx.doi.org/10.3390/computation10020024.

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Electromagnetic field propagation inside composite materials represents a challenge where fiber-scale simulation remains intractable using classical simulation methods. The present work proposes an original 3D simulation with a mesh resolution fine enough to resolve the fiber scale, thanks to the use of Proper Generalized Decomposition (PGD)-based space decomposition, which avoids the necessity of considering homogenized properties and considers the richest description of the involved physics from the solution of the Maxwell equations. This high-resolution simulation enables comparing the electromagnetic field propagation in a composite part, depending on the considered frequency and the fiber’s/wave polarization’s relative orientation. The electromagnetic fields are then post-processed to identify the heat generation terms and- the resulting induced thermal field. The results prove the ability of the PGD-based discretization to attain extremely high levels of resolution, the equivalent of 1010 finite-element degrees of freedom. The obtained results show an enhanced wave penetration when the electric field polarization coincides with the fiber orientation. On the contrary, when the electric field is polarized along the normal to the fiber orientation, both the penetration and the associated heating reduce significantly, compromising the use of homogenized models, rendering them unable to reproduce the observed behaviors.

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Khurshid, Ajab. "The Application of Micromechanical Modeling to Study the Non-Linear Behavior of Flexible Pavement under Truck Loading in Pakistan". International Journal for Research in Applied Science and Engineering Technology 9, n. 9 (30 settembre 2021): 923–32. http://dx.doi.org/10.22214/ijraset.2021.37975.

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Abstract: This report presents the work done to create a 3D model of a pavement structure, which incorporates in a most accurately way non damaging effects of asphalt layer considering the different layers that compose the pavement structure. A series of approaches have been considered from linear viscoelastic modelling using Maxwell model via UMAT subroutine to integrated viscoelastic response using Prony series available in the built in ABAQUS material library. During this work also other effects have been considered including the viscoelastic behaviour caused by creep, which is included via a separate CREEP subroutine. In order to predict also the non-linear effect of viscous elastic response the well-known Schapery's nonlinear viscoelastic constitutive model was considered. Implementing 3D Schapery’s model can be done by using again user material subroutine UMAT. It was found that the use of a nonlinear viscoelastic model substantially transformed the pavement response. A series of python scripts have been developed to create a multi-step analysis to simulate a cyclic loading application. Keywords: Viscoelasticity, Abaqus. Asphalt, Damage, Simulation, Modelling, Pavement design

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Bernat, Jakub, e Sławomir Stępień. "Induction motor analysis employing optimal torque predictor and massive conductor approach". Archives of Electrical Engineering 59, n. 1-2 (1 settembre 2010): 99–107. http://dx.doi.org/10.2478/s10171-010-0008-x.

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Induction motor analysis employing optimal torque predictor and massive conductor approachThis research presents a method for the simulation of the magneto-mechanical system dynamics taking motion and eddy currents into account. The major contribution of this work leans on the coupling the field-motion problem considering windings as the current forced massive conductors, modelling of the rotor motion composed of two conductive materials and the torque calculation employing the special optimal predictor combined with the modified Maxwell stress tensor method. The 3D model of the device is analysed by the time stepping finite element method. Mechanical motion of the rotor is determined by solving the second order motion equation. Both magnetic and mechanical equations are coupled in the iterative solving process. Presented method is verified by solving the TEAM Workshop Problem 30.

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