Recent zbMATH articles in MSC 78https://zbmath.org/atom/cc/782024-09-13T18:40:28.020319ZUnknown authorWerkzeugA mathematical description of the Weber nucleus as a classical and quantum mechanical systemhttps://zbmath.org/1540.340632024-09-13T18:40:28.020319Z"Frauenfelder, Urs"https://zbmath.org/authors/?q=ai:frauenfelder.urs-adrian"Weber, Joa"https://zbmath.org/authors/?q=ai:weber.joaSummary: Wilhelm Weber's electrodynamics is an action-at-a-distance theory which has the property that equal charges inside a critical radius become attractive. Weber's electrodynamics inside the critical radius can be interpreted as a classical Hamiltonian system whose kinetic energy is, however, expressed with respect to a \textit{Lorentzian} metric. In this article we study the Schrödinger equation associated with this Hamiltonian system, and relate it to Weyl's theory of singular Sturm-Liouville problems.Floquet stability of periodically stationary pulses in a short-pulse fiber laserhttps://zbmath.org/1540.350202024-09-13T18:40:28.020319Z"Shinglot, Vrushaly"https://zbmath.org/authors/?q=ai:shinglot.vrushaly"Zweck, John"https://zbmath.org/authors/?q=ai:zweck.john-wSummary: The quantitative modeling and design of modern short-pulse fiber lasers cannot be performed with averaged models because of large variations in the pulse parameters within each round trip. Instead, lumped models obtained by concatenating models for the various components of the laser are required. Since the optical pulses in lumped models are periodic, their linear stability is investigated using the monodromy operator, which is the linearization of the roundtrip operator about the pulse. A gradient-based optimization method is developed to discover periodic pulses. The computation of the gradient of the objective function involves numerical computation of the action of both the roundtrip operator and the adjoint of the monodromy operator. A novel Fourier split-step method is introduced to compute solutions of the linearization of the nonlinear, nonlocal, stiff equation that models optical propagation in the fiber amplifier. This method is derived by linearizing the two solution operators in a split-step method for the nonlinear equation. The spectrum of the monodromy operator consists of the essential spectrum, for which there is an analytical formula, and the eigenvalues. There is a multiplicity two eigenvalue at \(\lambda=1\), which is due to phase and translation invariance. The remaining eigenvalues are determined from a matrix discretization of the monodromy operator. Simulation results verify the accuracy of the numerical methods; show examples of periodically stationary pulses, their spectra, and their eigenfunctions; and discuss their stability.Self-consistent approximations in the theory of composites and their limitationshttps://zbmath.org/1540.350302024-09-13T18:40:28.020319Z"Mityushev, Vladimir"https://zbmath.org/authors/?q=ai:mityushev.vladimir-vSummary: Many attempts were undertaken to modify Maxwell's approach in the theory of composites. Self-consistent methods (effective medium approximation, mean field, Mori-Tanaka methods, reiterated homogenization etc) were advanced to determine the effective properties of composites. It is demonstrated by an example that these extensions are methodologically misleading. They lead to a plenty of illusory different formulas reduced to the Maxwell type, lower order estimation for dilute composites.
For the entire collection see [Zbl 1531.35008].Analysis of the transmission eigenvalue problem with two conductivity parametershttps://zbmath.org/1540.351202024-09-13T18:40:28.020319Z"Ceja Ayala, Rafael"https://zbmath.org/authors/?q=ai:ayala.rafael-ceja.1"Harris, Isaac"https://zbmath.org/authors/?q=ai:harris.isaac"Kleefeld, Andreas"https://zbmath.org/authors/?q=ai:kleefeld.andreas"Pallikarakis, Nikolaos"https://zbmath.org/authors/?q=ai:pallikarakis.nikolaos(no abstract)Direct imaging methods for reconstructing a locally rough interface from phaseless total-field data or phased far-field datahttps://zbmath.org/1540.352752024-09-13T18:40:28.020319Z"Li, Long"https://zbmath.org/authors/?q=ai:li.long.1"Yang, Jiansheng"https://zbmath.org/authors/?q=ai:yang.jiansheng"Zhang, Bo"https://zbmath.org/authors/?q=ai:zhang.bo"Zhang, Haiwen"https://zbmath.org/authors/?q=ai:zhang.haiwenSummary: This paper is concerned with the problem of inverse scattering of time-harmonic acoustic plane waves by a two-layered medium with a locally rough interface in two dimensions. A direct imaging method is proposed to reconstruct the locally rough interface from the phaseless total-field data measured on the upper half of the circle with a large radius at a fixed frequency or from the phased far-field data measured on the upper half of the unit circle at a fixed frequency. The presence of the locally rough interface poses challenges in the theoretical analysis of the imaging methods. To address these challenges, a technically involved asymptotic analysis is provided for the relevant oscillatory integrals involved in the imaging methods, based mainly on the techniques and results in our recent work [``Uniform far-field asymptotics of the two-layered Green function in 2D and application to wave scattering in a two-layered medium'', Preprint, \url{arXiv:2208.00456}] on the uniform far-field asymptotics of the scattered field for acoustic scattering in a two-layered medium. Finally, extensive numerical experiments are conducted to demonstrate the feasibility and robustness of our imaging algorithms.Rigorous derivation of the compressible Navier-Stokes equations from the two-fluid Navier-Stokes-Maxwell equationshttps://zbmath.org/1540.353162024-09-13T18:40:28.020319Z"Peng, Yi"https://zbmath.org/authors/?q=ai:peng.yi"Wang, Huaqiao"https://zbmath.org/authors/?q=ai:wang.huaqiaoSummary: In this paper, we rigorously derive the compressible one-fluid Navier-Stokes equations from the scaled compressible two-fluid Navier-Stokes-Maxwell equations under the assumption that the initial data are well prepared. We justify the singular limit by proving the uniform decay of the error system, which is obtained by using the elaborate energy estimates.Rogue wave solutions for the \((3 + 1)\)-dimensional generalized Camassa-Holm-Kadomtsev-Petviashvili equationhttps://zbmath.org/1540.353482024-09-13T18:40:28.020319Z"Liu, Ying"https://zbmath.org/authors/?q=ai:liu.ying.7|liu.ying.21|liu.ying.26|liu.ying.23|liu.ying.8|liu.ying.9|liu.ying.19|liu.ying.6|liu.ying|liu.ying.32|liu.ying.5"Yang, Yunqing"https://zbmath.org/authors/?q=ai:yang.yunqingSummary: In this paper, the \((3 + 1)\)-dimensional generalized Camassa-Holm-Kadomtsev-Petviashvili equation is investigated by Hirota bilinear method, from which the first, second and third order rogue wave solutions are derived. The relationships between the parameters and the amplitude, width and center of rogue wave are discussed. At the same time, several evolution and density plots are present to exhibit the dynamical structure of the rogue wave solutions. The results may be useful in nonlinear optics and other physically relevant integrable systems.Dust acoustic inertial Alfvénic nonlinear structures in an electron depleted dusty plasmahttps://zbmath.org/1540.353522024-09-13T18:40:28.020319Z"Slathia, Geetika"https://zbmath.org/authors/?q=ai:slathia.geetika"Kaur, Rajneet"https://zbmath.org/authors/?q=ai:kaur.rajneet"Saini, N. S."https://zbmath.org/authors/?q=ai:saini.nareshpal-singhSummary: In this investigation, the propagation properties of dust inertial Alfvén wave (DIAW) solitons, rogons, and breather structures have been studied in a magnetised electron-depleted two fluids plasma consisting of negatively charged dust and positively charged ions. The Korteweg-de Vries (KdV) equation has been derived by using the reductive perturbation method (RPM) to study the properties of solitons. Further, the nonlinear Schrödinger equation (NLSE) has also been derived by employing a suitable transformation in the KdV equation. The evolution of various kinds of nonlinear structures such as rogons, Akhmediev breathers (AB), and Kuznetsov-Ma breathers (KM) has been elucidated from the different rational solutions of the nonlinear Schrödinger equation. The impact of various physical parameters, such as the dust plasma beta and the angle of propagation of different species, on the salient properties of DIAW solitons, rogons, and breather structures has been studied numerically.Solitonic rogue waves dynamics in a nonlinear electrical transmission line with the next nearest neighbor couplingshttps://zbmath.org/1540.353772024-09-13T18:40:28.020319Z"Ndzana, Fabien II"https://zbmath.org/authors/?q=ai:ndzana.fabien-ii"Djelah, Gabriel"https://zbmath.org/authors/?q=ai:djelah.gabriel"Mohamadou, Alidou"https://zbmath.org/authors/?q=ai:mohamadou.alidouSummary: In this paper, a nonlinear transmission network with next-nearest-neighbor couplings is considered. We show how the propagation dynamics of the waves through the network can be described by a nonlinear Schrödinger (NLS) equation with an external linear potential after using the reductive perturbation method in the semidiscrete limit. Analytic solitonic solutions of the first and second order rogue waves in the system are predicted and analyzed. Taking into account the bandwidth frequencies where the network may exhibit modulational instability, the rogue waves propagation have been expected. One of the main results of our work is that with the introduction of the second neighbors parameter \(L_3\) in the network, two kind of rogue wave signals, either two bright rogue wave signals or one bright and one dark rogue wave signal, may simultaneously propagate at the same frequency through the network. The effects of both next-nearest-neighbor couplings parameter \(L_3\) and the strength \(\chi\) of the linear potential on the dynamics of rogue waves through the network are also investigated. The characteristics of the rogue wave are investigated quantitatively and qualitatively with the introduction of the second neighbors couplings as relevant network parameters.Study of gain and trajectories in elliptical electron beam considering a planar wiggler and self fields and ion-channel in free electron laserhttps://zbmath.org/1540.353852024-09-13T18:40:28.020319Z"Abdollahi, F. S."https://zbmath.org/authors/?q=ai:abdollahi.f-s"Abdoli-Arani, A."https://zbmath.org/authors/?q=ai:abdoli-arani.abbas"Mohsenpour, T."https://zbmath.org/authors/?q=ai:mohsenpour.tSummary: In this study, the relativistic electron beam with an elliptical cross-section is introduced instead of the relativistic electron beam with a circular cross-section in free-electron laser (FEL). Influences of ion-channel guiding, axial magnetic field, Planar Wiggler Magnetic Field (PWMF) and self-fields on trajectories of the elliptical relativistic electron beam have also been investigated. At first, it was assumed that the PWMF is applied along the minor axis of the beam cross-section ellipse. In the second case, the PWMF was applied along the major axis of beam cross-section ellipse, the results of which were compared for the two cases. Effects of elliptical cross-section demotions and elliptical electron beam density on electron trajectory have been studied. The results were compared in the limit that the elliptical electron beam is converted to a circular electron beam, which has also been graphically presented. Moreover, a limit case in which the elliptical beam is converted into a sheet beam was studied. Furthermore, a formula was obtained for the small signal gain in a FEL with elliptical electron beam. The obtained gain for a FEL, together with a relativistic electron beam with an elliptical cross section was compared to the maximum gain for a FEL together with a relativistic electron beam with a circular cross section. It is shown that increasing the ratio of the semi-major to semi-minor axes of the beam cross-section causes the gain rate of the FEL to increases. We investigated a study of electron trajectories and dispersion equation in relativistic electron beam with elliptical cross section under the influence of electromagnetic wave wiggler and axial magnetic field considering ion-channel guiding and self fields in Appendix A.Analysis and computation for the scattering problem of electromagnetic waves in chiral mediahttps://zbmath.org/1540.353862024-09-13T18:40:28.020319Z"Bao, Gang"https://zbmath.org/authors/?q=ai:bao.gang"Zhang, Lei"https://zbmath.org/authors/?q=ai:zhang.lei.14Summary: This paper considers an obstacle scattering problem in a chiral medium under circularly polarized oblique plane wave incidence, which can be represented as a combination of a left-circularly polarized plane wave and a right-circularly polarized one. We apply a reduced model problem with coupled oblique derivative boundary conditions, describing the cross-coupling effect of electric and magnetic fields. A novel boundary integral equation is constructed by introducing single-layer potential operators and the corresponding normal and tangential derivative operators. The corresponding properties are obtained by splitting techniques to overcome the singularity of integral operators. A numerical method for solving the boundary integral equation is developed, whose convergence is proved. Numerical results are presented to show the performance of the proposed method.Numerical simulation of resistance furnaces by using distributed and lumped modelshttps://zbmath.org/1540.353872024-09-13T18:40:28.020319Z"Bermúdez, A."https://zbmath.org/authors/?q=ai:bermudez.ana|bermudez.alfredo|bermudez.alejandro|bermudez.aurelio"Gómez, D."https://zbmath.org/authors/?q=ai:gomez-ramirez.danny-arlen-de-jesus|gomez.delfina|gomez.domingo|gomez.david-m|gomez.desiree-gijon|gomez.dolores|gomez.david-delgado|gomez.daniel-armando"González, D."https://zbmath.org/authors/?q=ai:gonzalez.dashleen|gonzalez.danielle|gonzalez.denis-deniz|gonzalez.david-r|gonzalez.david-j|gonzalez.damaris-pascual|gonzalez.david-s|gonzalez.diego-luis|gonzalez.daniel|gonzalez.dania|gonzalez.damien|gonzalez.domingo|gonzalez.diego-luizThe authors propose two models concerning the current to be supplied in a resistance furnace for achieving a desired power output. The simply connected domain \(\Omega \) corresponding to the furnace is decomposed as \(\Omega =\Omega _{C}\cup \Omega _{D}\), representing conductors and dielectrics media, respectively. \(\Omega _{R}\) is the part of \(\Omega _{C}\) built with the resistive heater and its terminals. \(\Omega \) is supposed to have a Lipschitz-continuous boundary \(\Gamma \). \(\overline{ \Gamma }_{R}=\partial \Omega _{R}\cap \Gamma \) is the outer boundary of \( \Omega _{R}\) which consists of three separate components \(\Gamma _{R}^{k}\), \( k=1,2,3\), and \(\overline{\Gamma }_{D}=\partial \Omega _{D}\cap \Gamma \) that of the dielectric domain. The problem under consideration is written as: For given complex numbers \(I_{k}\), \(k=1,2\), find a vector field \(A\) defined in \( \Omega \), and a scalar field \(V\) defined in \(\Omega _{C}\) and constant on \( \Gamma _{R}^{1}\) and \(\Gamma _{R}^{2}\), such that: \(\sigma (i\omega A+\mathrm{grad}\,V)+\mathrm{curl}(\frac{1}{\mu }\mathrm{curl}\,A)=0\), \(\operatorname{div}A=0\) in \(\Omega \), \(A\times n=0\) on \(\Gamma \), \(\sigma (i\omega A+\mathrm{grad}\,V)\cdot n=0\) on \(\partial \Omega _{C}\setminus \Gamma _{R}\), \(V=0\) on \(\Gamma _{R}^{3}\), \(\int_{\Gamma _{R}^{k}}\sigma (i\omega A+\mathrm{grad}\,V)\cdot ndS=-I_{k}\), \(k=1,2\). This distributed model is numerically solved using the finite element method. The lumped model relies on calculating a reduced impedance associated with an equivalent circuit model. The authors here assumes further hypotheses on the behavior of the furnace. They finally present and discuss the numerical simulations they obtain considering an industrial resistance furnace.
Reviewer: Alain Brillard (Riedisheim)Regularization of the volume integral operator of electromagnetic scatteringhttps://zbmath.org/1540.353882024-09-13T18:40:28.020319Z"Matoussi, Ghassen"https://zbmath.org/authors/?q=ai:matoussi.ghassen"Sakly, Hamdi"https://zbmath.org/authors/?q=ai:sakly.hamdiSummary: We consider the scattering of time-harmonic electromagnetic waves by a bounded, penetrable, homogeneous obstacle. This problem admits an equivalent formulation in terms of a strongly singular volume integral equation (VIE). In this paper, and for smooth interfaces, we construct a regularizer for the operator that describes the VIE, i.e., we give an explicit representation of an integral operator, which, applied to the VIE, transforms it into the form ``identity plus a compact operator''. The employed strategy is inspired by the previous work [\textit{M. Costabel} et al., C. R., Math., Acad. Sci. Paris 350, No. 3--4, 193--197 (2012; Zbl 1247.78011)].Global sensitivity analysis of plasma instabilities via active subspaceshttps://zbmath.org/1540.353972024-09-13T18:40:28.020319Z"Terrab, Soraya"https://zbmath.org/authors/?q=ai:terrab.soraya"Pankavich, Stephen"https://zbmath.org/authors/?q=ai:pankavich.stephen-d|pankavich.stephenSummary: Active subspace analysis is a useful computational tool to identify and exploit the most important linear combinations in the space of a model's input parameters. These directions depend inherently on a quantity of interest, which can be represented as a function from input parameters to model outputs. As the dynamics of many plasma models are driven by potentially uncertain parameter values, the utilization of active subspaces to perform global sensitivity analysis represents an important step in understanding how certain physical phenomena depend upon fluctuations in the values of these parameters. In the current paper, we construct and implement new computational methods to quantify the induced uncertainty within the growth rate generated by perturbations in a collisionless plasma modeled by the one-dimensional Vlasov-Poisson system near an unstable, spatially-homogeneous steady state in the linear regime.Low-regret optimal control for an inverse electrocardiological problem with incomplete datahttps://zbmath.org/1540.354182024-09-13T18:40:28.020319Z"Ainseba, B."https://zbmath.org/authors/?q=ai:ainseba.bedreddine"Omrane, A."https://zbmath.org/authors/?q=ai:omrane.abdennebiSummary: This work deals with an inverse electrocardiological problem considering the reconstruction of where one has to reconstruct the heart transmembrane potential from thorax's high density measurements. The problem will be solved as an optimal control one for a partial differential system with incomplete data. The electrical activity on the heart is here modelled by a system of FitzHugh-Nagumo's type where the initial conditions corresponding to the transmembrane potential and to the gating variables are unknown. We use the low-regret optimal control method by \textit{J. L. Lions} [Some aspects of the optimal control of distributed parameter systems. Society for Industrial and Applied Mathematics (SIAM), Philadelphia, PA (1972; Zbl 0275.49001); C. R. Acad. Sci., Paris, Sér. I 315, No. 12, 1253--1257 (1992; Zbl 0766.93033)] to tackle this problem. We prove the existence and uniqueness of a low-regret control that we characterise by a singular optimality system.The Korteweg-de Vries equation with forcing involving products of eigenfunctionshttps://zbmath.org/1540.370922024-09-13T18:40:28.020319Z"Fokas, A. S."https://zbmath.org/authors/?q=ai:fokas.athanassios-s"Latifi, A."https://zbmath.org/authors/?q=ai:latifi.anouchah|latifi.abderrazak-mThis paper is concerned with the KdV equation with forcing terms involving quadratic products of eigenfunctions of the associated Lax pair. More specifically, the authors prove the integrability of the following forced extension of the KdV equation:
\[
u_t + \alpha(u_{xxx} + 6uu_x) = d_x(x,t) + 2h_x(x,t),
\]
where \(d\) and \(h\) involve products of eigenfunctions of the associated Lax pair.
They show how this forced KdV equation can be solved in terms of the solution of a Riemann-Hilbert problem. They also present two important physical applications of the above equation, including one involving laser-plasma interaction and a second involving resonant gravity-capillary waves.
Reviewer: Julie L. Levandosky (Framingham)Analysis and application of two novel finite element methods for solving Ziolkowski's PML model in the integro-differential formhttps://zbmath.org/1540.653812024-09-13T18:40:28.020319Z"Li, Jichun"https://zbmath.org/authors/?q=ai:li.jichun"Zhu, Li"https://zbmath.org/authors/?q=ai:zhu.li.2Summary: Since the introduction of the perfectly matched layer (PML) technique by \textit{J.-P. Berenger} [J. Comput. Phys. 114, No. 2, 185--200 (1994; Zbl 0814.65129)] to solve the time-dependent Maxwell's equations in unbounded domains, many different PML models have been developed and adopted for various wave propagation problems in unbounded domains. In this paper, we are interested in a physically inspired PML model proposed by \textit{R. W. Ziolkowski} [Comput. Methods Appl. Mech. Eng. 169, No. 3--4, 237--262 (1999; Zbl 0960.78018)]. To reduce the unknowns and make more efficient numerical methods, we reformulate the original model in integro-differential form. We propose and analyze two novel finite element methods for solving this equivalent PML model. Stability and convergence analysis are established for both schemes. Numerical results are presented to support our analysis and demonstrate the effectiveness of wave absorption of this equivalent PML.Wave propagation in high-contrast media: periodic and beyondhttps://zbmath.org/1540.654092024-09-13T18:40:28.020319Z"Fressart, Élise"https://zbmath.org/authors/?q=ai:fressart.elise"Verfürth, Barbara"https://zbmath.org/authors/?q=ai:verfurth.barbaraSummary: This work is concerned with the classical wave equation with a high-contrast coefficient in the spatial derivative operator. We first treat the periodic case, where we derive a new limit in the one-dimensional case. The behavior is illustrated numerically and contrasted to the higher-dimensional case. For general unstructured high-contrast coefficients, we present the Localized Orthogonal Decomposition and show a priori error estimates in suitably weighted norms. Numerical experiments illustrate the convergence rates in various settings.A posteriori error estimation for the optimal control of time-periodic eddy current problemshttps://zbmath.org/1540.654672024-09-13T18:40:28.020319Z"Wolfmayr, Monika"https://zbmath.org/authors/?q=ai:wolfmayr.monikaSummary: This work presents the multiharmonic analysis and derivation of functional type a posteriori estimates of a distributed eddy current optimal control problem and its state equation in a time-periodic setting. The existence and uniqueness of the solution of a weak space-time variational formulation for the optimality system and the forward problem are proved by deriving inf-sup and sup-sup conditions. Using the inf-sup and sup-sup conditions, we derive guaranteed, sharp and fully computable bounds of the approximation error for the optimal control problem and the forward problem in the functional type a posteriori estimation framework. We present here the first computational results on the derived estimates.One-dimensional lattice Boltzmann simulation of parallel plate dielectric barrier discharge plasma in atmospheric argonhttps://zbmath.org/1540.761492024-09-13T18:40:28.020319Z"Choe, Yong Son"https://zbmath.org/authors/?q=ai:choe.yong-son"Kim, Yong Jun"https://zbmath.org/authors/?q=ai:kim.yong-jun"Ri, Thae Nam"https://zbmath.org/authors/?q=ai:ri.thae-nam"Kim, Tong Kuk"https://zbmath.org/authors/?q=ai:kim.tong-kukSummary: The purpose of this paper is to apply lattice Boltzmann (LB) D1Q3 scheme to numerical simulation of multi-component plasma by dielectric barrier discharge (DBD). The DBD in atmospheric argon is generated in a small gap of 0.5 mm between two parallel plate electrodes, and driven by applying high voltage AC. In order to find characteristics of the DBD plasma, the LB numerical model is setup coupled with continuity and Poisson equations. The simulation results enable us to adopt LB method for simulation of DBD plasma. The electron density and electron energy are, at most, \(2.5 \times 10^{18}\text{m}^{-3}\) and 8.1 eV when frequency is 20 kHz, voltage 3000 V, and relative permittivity 20. The influences of relative permittivity, driving frequency and dielectric width on the plasma are analyzed. The DBD plasma can be enhanced with higher relative permittivity and driving frequency in terms of electron energy and electron density.Special issue ELECTRIMACS 2019 engineering modelling and computational simulation for analysis and optimization in electrical power engineeringhttps://zbmath.org/1540.780012024-09-13T18:40:28.020319Z"Petrone, Giovanni"https://zbmath.org/authors/?q=ai:petrone.giovanni"Zamboni, Walter"https://zbmath.org/authors/?q=ai:zamboni.walter"Batzelis, Efstratios"https://zbmath.org/authors/?q=ai:batzelis.efstratios"Manganiello, Patrizio"https://zbmath.org/authors/?q=ai:manganiello.patrizio"Blasco-Gimenez, Ramon"https://zbmath.org/authors/?q=ai:blasco-gimenez.ramonFrom the text: This special issue briefly called ``ELECTRIMACS 2019 ENGINEERING'' collects peer-reviewed research papers presented at ELECTRIMACS 2019, that is the 13th Conference of the IMACS Technical Committee ``ELECTRIMACS''. The conference was held in Salerno, Italy, from 21st to 23rd May 2019.Prefacehttps://zbmath.org/1540.780022024-09-13T18:40:28.020319Z"Roboam, Xavier"https://zbmath.org/authors/?q=ai:roboam.xavier"Monmasson, Eric"https://zbmath.org/authors/?q=ai:monmasson.eric"Blasco-Gimenez, Ramon"https://zbmath.org/authors/?q=ai:blasco-gimenez.ramon"Robyns, Benoit"https://zbmath.org/authors/?q=ai:robyns.benoit"Spagnuolo, Giovanni"https://zbmath.org/authors/?q=ai:spagnuolo.giovanni"Patin, Nicolas"https://zbmath.org/authors/?q=ai:patin.nicolas"Bruno, Sareni"https://zbmath.org/authors/?q=ai:bruno.sareniFrom the text: The guest editorial team is pleased to introduce the ELECTRIMACS 2017 Special Issue.
ELECTRIMACS 2017, the 12th International Conference on Modeling and Simulation of Electric Machines, Converters and Systems organized by the Technical Committee 1 (TC1) of IMACS, took place in Toulouse, France from 4th to 6th of July 2017.Special issue ELECTRIMACS 2019 energy modelling and computational simulation for control and diagnosis in renewable energy systems, energy storage, innovative devices and materialshttps://zbmath.org/1540.780032024-09-13T18:40:28.020319ZFrom the text: This special issue briefly called ``ELECTRIMACS 2019 ENERGY'' collects peer-reviewed research papers presented at ELECTRIMACS 2019, that is the 13th conference of the IMACS technical committee ``ELECTRIMACS''. The conference was held in Salerno, Italy, from 21st to 23rd May 2019.Modeling and analysis of eddy current losses in permanent magnet machines with multi-stranded bundle conductorshttps://zbmath.org/1540.780042024-09-13T18:40:28.020319Z"Arumugam, Puvan"https://zbmath.org/authors/?q=ai:arumugam.puvan"Dusek, Jiri"https://zbmath.org/authors/?q=ai:dusek.jiri"Mezani, Smail"https://zbmath.org/authors/?q=ai:mezani.smail"Hamiti, Tahar"https://zbmath.org/authors/?q=ai:hamiti.tahar"Gerada, Chris"https://zbmath.org/authors/?q=ai:gerada.chrisSummary: This paper investigates the influence of eddy current losses in multi-stranded bundle conductors employed in out-runner permanent magnet machines, by adopting an analytical model. The analytical model is based on a sub-domain field model that solves the two-dimensional magnetostatic problem using the separation of variables technique for each of the non-magnetically permeable machine sub-domains: PM, airgap and slots. The validity and accuracy of the proposed model is verified using finite element analysis and then used to investigate the eddy current losses. The machine considered for the analysis has 36 slots and 42-poles previously designed for aircraft taxiing. The influence of the number of turns and the conductor cross-sectional area are investigated. It is shown that efficiency can be improved considerably by the choice of multi-stranded bundle conductors.Comparison between \(i_{\operatorname{g}}\) integration and \(v_{\operatorname{gs}}\) derivation methods dedicated to fast short-circuit 2D diagnosis for wide bandgap power transistorshttps://zbmath.org/1540.780052024-09-13T18:40:28.020319Z"Barazi, Yazan"https://zbmath.org/authors/?q=ai:barazi.yazan"Rouger, Nicolas"https://zbmath.org/authors/?q=ai:rouger.nicolas"Richardeau, Frédéric"https://zbmath.org/authors/?q=ai:richardeau.fredericSummary: This study presents and compares two original high-speed protection circuit methods, namely, \(i_{\operatorname{g}}\) integration and \(v_{\operatorname{gs}}\) derivation, against short-circuit types, referred to as, the hard switch fault and fault under load. Since the gate-drain capacitor \(C_{\operatorname{gd}}\) of a power device depends on the drain to source voltage \(v_{\operatorname{ds}} \), it can become an original native sensor to monitor the switching operation and so detect the unwanted \(v_{\operatorname{ds}}\) transition or the absence of the \(v_{\operatorname{ds}}\) transition by monitoring only \(v_{\operatorname{gs}} \). The use of only low-voltage monitoring, such as \(v_{\operatorname{gs}} \), is an essential step to integrate fast and embedded new detection methods into a low-voltage application-specific integrated circuit gate driver, in particular for wide bandgap power transistors. The \(C_{g d}\) capacitor plays a major part in the two detection methods. The first method is based on dedicated two-dimensional monitoring of the gate charge transferred in a time interval combined with gate voltage monitoring. The second method consists of the reconstruction of the \(dv_{g s} /dt\) by means of a capacitive current sensing to provide the \(v_{\operatorname{gs}}\) derivation combined with the \(v_{g s}\) monitoring. Comparison and simulation of the methods based on a \textit{C2M0025120D} SiC MOSFET device under LTspice are made to verify the validity of the methods. In terms of detection speed of the short circuit, a detection time of 200 ns is obtained for both methods. Experimental waveforms based on \textit{C3M0120090J} SiC MOSFET device were included into LTspice to push furthermore the methods to their limits and validate the approaches. Both methods are easy to design and to integrate. However, the robustness and the speed of detection trade-off of all these methods should be analysed and compared relative to the critical functionalities.An induction machine and power electronic test system on a field-programmable gate arrayhttps://zbmath.org/1540.780062024-09-13T18:40:28.020319Z"Dufour, Christian"https://zbmath.org/authors/?q=ai:dufour.christian"Cense, Sébastien"https://zbmath.org/authors/?q=ai:cense.sebastien"Bélanger, Jean"https://zbmath.org/authors/?q=ai:belanger.jeanSummary: This paper presents a field-programmable gate array (FPGA) test system composed of an induction machine, configurable as a doubly-fed induction machine or squirrel-cage induction machine, with power electronic converter models suitable for virtual motor drive control development and testing. The IM model is designed so that all parameters can be modified online without stopping the simulation. The power electronic part is customizable using a variable topology FPGA solver called Electric Hardware Solver (eHS). Permanent magnet synchronous machine and switched reluctance motor drive FPGA models are also discussed. The system is designed for fast design iteration process by allowing circuit and parameter modification using a unique bitstream. The system allows control engineers to validate production controllers in real-time, using virtual motor drives. The paper also briefly explains permanent magnet synchronous motor drives and switched reluctance motor drive implementations on FPGA.Yokeless radial electrodynamic bearinghttps://zbmath.org/1540.780072024-09-13T18:40:28.020319Z"Dumont, C."https://zbmath.org/authors/?q=ai:dumont.christophe|dumont.cyrielle"Kluyskens, V."https://zbmath.org/authors/?q=ai:kluyskens.v"Dehez, B."https://zbmath.org/authors/?q=ai:dehez.brunoSummary: When null-flux, passive electrodynamic bearings include a ferromagnetic yoke in front of the permanent magnets, the stiffness associated with the radial centering force becomes negative under a critical speed. This yields a strong instability and the necessity of using mechanical launch bearings at low speeds. In this paper, an electrodynamic bearing without ferromagnetic yoke is proposed. An analytical 2D model of the bearing is presented and some hypotheses are validated. The model is then used to perform a first analysis of the bearing performance. The force predictions correspond to expectations: the stiffness never reaches negative values. It is also shown that for given geometrical parameters, the performance of the studied bearing can be improved by choosing the appropriate number of phases and number of pole pairs of the winding.Thermal modeling of an asymmetrical totally enclosed permanent magnet integrated starter generatorhttps://zbmath.org/1540.780082024-09-13T18:40:28.020319Z"Khlissa, Radhouane"https://zbmath.org/authors/?q=ai:khlissa.radhouane"Vivier, Stephane"https://zbmath.org/authors/?q=ai:vivier.stephane"Friedrich, Guy"https://zbmath.org/authors/?q=ai:friedrich.guy"El Kadri Benkara, Khadija"https://zbmath.org/authors/?q=ai:el-kadri-benkara.khadija"Assaad, Bassel"https://zbmath.org/authors/?q=ai:assaad.basselSummary: Some electromechanical systems involve totally enclosed electrical machines. In these cases, forced internal air cooling, for instance by the use of fans, is nearly impossible. However, in the same time, permanent magnet machines have to expel their internal rotor losses. In this context, an accurate estimate of heat exchange transfers and heat sources are important, for instance for the determination of the temperature distribution. This can be used for future designs of the same type of machine. This paper details the thermal modeling of a totally enclosed permanent magnet machine, such as an integrated starter generator (ISG). For this purpose, a lumped parameter network is built. Thermal conduction, convection and radiation heat transfer modes are considered. Losses are calculated using both analytical expressions and (coupled) electromagnetic finite element analysis (FEA). Simulation results are compared and validated with experimental data.Influence of stator slot openings on losses and torque in axial flux permanent magnet machineshttps://zbmath.org/1540.780092024-09-13T18:40:28.020319Z"Sergeant, Peter"https://zbmath.org/authors/?q=ai:sergeant.peter"Vansompel, Hendrik"https://zbmath.org/authors/?q=ai:vansompel.hendrik"Dupré, Luc"https://zbmath.org/authors/?q=ai:dupre.luc-rSummary: Among the different geometrical parameters to be chosen during design of axial flux permanent magnet synchronous machines, the width of the stator slot openings near the air gap is an important parameter: it has a major influence on the power loss in the stator core and in the permanent magnets on the two rotors of the studied type of axial flux machines. Moreover, the stator slot openings parameter has a converse impact on both power losses. On the one hand, the increase in stator slot openings results in a reduction of the power losses in the stator core elements. On the other hand, it also results in increased loss in the permanent magnets. Also the torque is reduced for large but also for very small slot openings. This paper deals with axial flux machines of the YASA type: yokeless and segmented armature. It is shown that the slot openings contribute to an unequal flux density level over the different laminations in the stator core. Insight in the impact of the slot openings variation on both power losses (in stator iron and in permanent magnets) is provided, and an illustrative case is discussed in which the impact of the slot openings variation on both power losses is examined quantitatively.Analysis of torque ripple reduction in a segmented-rotor synchronous reluctance machine by optimal currentshttps://zbmath.org/1540.780102024-09-13T18:40:28.020319Z"Wu, Hailong"https://zbmath.org/authors/?q=ai:wu.hailong.1"Depernet, Daniel"https://zbmath.org/authors/?q=ai:depernet.daniel"Lanfranchi, Vincent"https://zbmath.org/authors/?q=ai:lanfranchi.vincentSummary: The research about synchronous reluctance machine (SynRM) has been revived in the last decades because of its advantages. But the torque ripple limits the performances of SynRM. Based on the feature of SynRM, this paper proposes a new method in order to calculate the optimal currents which contain many harmonics. Based on the proposed torque function, this method does not use the specific stator inductances to reduce torque ripple. Then, the compensated torques by supplying different orders of optimal currents are compared and analyzed. Besides, the influence of magnetic saturation on the proposed method is also studied. Thirdly, the added current harmonics could increase the losses of the machine. Therefore, the copper losses of the machine are also analyzed. It has shown that the proposed approach can decrease torque ripple effectively.Modelling and analysis of equivalent SISO \(d\)-\(q\) impedance of grid-connected convertershttps://zbmath.org/1540.780112024-09-13T18:40:28.020319Z"Xiao, Qi"https://zbmath.org/authors/?q=ai:xiao.qi"Mattavelli, Paolo"https://zbmath.org/authors/?q=ai:mattavelli.paolo"Khodamoradi, Aram"https://zbmath.org/authors/?q=ai:khodamoradi.aram"Loh, Poh Chiang"https://zbmath.org/authors/?q=ai:loh.poh-chiangSummary: Small-signal stability of three-phase grid-connected converters can be analysed by using the impedance-based method in \(d\)-\(q\) frame. Based on this approach, the \(d\)-\(q\) impedance models of both source and load subsystems are represented with 2-by-2 matrices, and their ratio (known as the return ratio matrix) is used for stability assessment. This, however, requires to apply the generalized Nyquist criterion (GNC), due to the intrinsic multi-input multi-output (MIMO) property of the \(d\)-\(q\) system. During the process, some complexities are inevitably caused because of the need to calculate the ratio of the impedance matrices, and to obtain the eigenvalues of the return ratio matrix. In this context, this paper presents an equivalent single-input single-output (SISO) model for the \(d\)-\(q\) impedance of three-phase grid-connected converters, which leads to two scalar impedance ratios of \(d\)- and \(q\)-axis, instead of the conventional 2-by-2 return ratio matrix. Consequently, the stability of the two SISO systems can be analysed by using the classic Nyquist stability criterion (NC), resulting in a much simpler and more intuitive analysis process than GNC. The equivalence between the original MIMO \(d\)-\(q\) impedance model and the proposed SISO model in stability assessment is verified by comparing their stability conditions. As an example of applying this approach, the effects of PLL, grid impedance, and power control on a grid-connected converter are investigated. The performed analysis is finally validated by Matlab/Simulink simulations.Spectral properties of conservative, dispersive, and absorptive photonic crystalshttps://zbmath.org/1540.780122024-09-13T18:40:28.020319Z"Engström, Christian"https://zbmath.org/authors/?q=ai:engstrom.christian"Torshage, Axel"https://zbmath.org/authors/?q=ai:torshage.axelSummary: This article reviews both recent progress on the mathematics of dispersive and absorptive photonic crystals and well-established results on conservative photonic crystals. The focus is on properties of the photonic band structures and we also provide results that are of importance for the understanding of lossy metal-dielectric photonic crystals.
{\copyright} 2018 WILEY-VCH Verlag GmbH \& Co. KGaA, WeinheimMathematical basis for a mixed inverse scattering problemhttps://zbmath.org/1540.780132024-09-13T18:40:28.020319Z"Wu, Qinghua"https://zbmath.org/authors/?q=ai:wu.qinghua"Yan, Guozheng"https://zbmath.org/authors/?q=ai:yan.guozhengSummary: In this paper we consider the scattering of an electromagnetic time-harmonic plane wave by an infinite cylinder having an open arc and a bounded domain in \(R^2\) as cross section. To this end, we solve a mixed scattering problem for the Helmholtz equation in \(R^2\) where the scattering object is a combination of a crack \(\Gamma\) and a bounded obstacle \(D\), and we set suitable boundary conditions on \(\Gamma\) and \(\partial D (\partial D \in C^2)\). The boundary integral method is employed to study the direct scattering problem. The mathematical basis is given to reconstruct the shape of the crack and the obstacle by using the linear sampling method. The numerical examples are given to show the viability of the method.Internal scales and dispersive properties of microstructured materialshttps://zbmath.org/1540.780142024-09-13T18:40:28.020319Z"Peets, Tanel"https://zbmath.org/authors/?q=ai:peets.tanelSummary: The Mindlin-Engelbrecht-Pastrone model is used for describing 1D longitudinal waves in microstructured solids. The effect of the underlying microstructure is best seen in the emergence of the optical dispersion branch. Dispersive properties of the Mindlin-Engelbrecht-Pastrone model are analyzed. It is shown by making use of the solutions to the boundary value problem that the influence of the optical dispersion branch has a significant effect on wave motion as shown in numerical experiments.Dynamic metasurface control using deep reinforcement learninghttps://zbmath.org/1540.780152024-09-13T18:40:28.020319Z"Zhao, Ying"https://zbmath.org/authors/?q=ai:zhao.ying"Li, Liang"https://zbmath.org/authors/?q=ai:li.liang"Lanteri, Stéphane"https://zbmath.org/authors/?q=ai:lanteri.stephane"Viquerat, Jonathan"https://zbmath.org/authors/?q=ai:viquerat.jonathanSummary: Dynamic metasurface is an emerging concept for achieving a flexible control of electromagnetic waves. Generalized sheet transition conditions (GSTCs) can be used to model the relationship between the electromagnetic response and surface susceptibility parameters characterizing a metasurface. However, when it comes to the inverse problem of designing and controlling a metasurface in a space-time varying context based on GSTCs, the dynamic synthesis of the susceptibility parameters is a difficult and non-intuitive task. In this paper, we transform the inverse problem of solving dynamic susceptibility parameters into a sequence of control problems. Based on FDTD numerical simulations, a Deep Reinforcement Learning (DRL) framework using a proximal policy optimization (PPO) algorithm and a fully connected neural network is designed to control the susceptibility parameters intelligently and efficiently, promoting the further expansion of the application range of metasurface and thus helping realize more flexible and effective control of electromagnetic waves. We provide numerical results in a one-dimensional setting to show the applicability, correctness and effectiveness of the proposed approach.Convergence analysis of back-EMF MRAS observers used in sensorless control of induction motor driveshttps://zbmath.org/1540.780162024-09-13T18:40:28.020319Z"Bensiali, N."https://zbmath.org/authors/?q=ai:bensiali.n"Etien, E."https://zbmath.org/authors/?q=ai:etien.erik|etien.eric"Benalia, N."https://zbmath.org/authors/?q=ai:benalia.nSummary: This paper seeks to analyse stability and dynamics of back EMF MRAS based approach used in sensorless control of induction motors. Stability analysis is investigated to show unstable zones and it is explored using a state representation. A new rotor speed estimator is designed to achieve the stability in the various operating modes except for the inobservability line.Power operating domain of a cascaded doubly fed induction machinehttps://zbmath.org/1540.780172024-09-13T18:40:28.020319Z"El Achkar, Maria"https://zbmath.org/authors/?q=ai:el-achkar.maria"Mbayed, Rita"https://zbmath.org/authors/?q=ai:mbayed.rita"Salloum, Georges"https://zbmath.org/authors/?q=ai:salloum.georges"Patin, Nicolas"https://zbmath.org/authors/?q=ai:patin.nicolas"Ballois, Sandrine Le"https://zbmath.org/authors/?q=ai:le-ballois.sandrine"Monmasson, Eric"https://zbmath.org/authors/?q=ai:monmasson.ericSummary: The paper deals with the steady state operating limits of a cascaded doubly fed induction machine (CDFIM) in terms of active and reactive powers. An analytic method is suggested to derive the power region, in which the machine can operate safely without exceeding its rated parameters. The proposed steady-state analytical study has been thoroughly validated by simulations using an elaborated model of the CDFIM implemented on Matlab-Simulink. It is shown that the power capability is subject to several limitations. For a limited speed range the reactive power consumption and generation are determined by the stators current maximum values. The study is further extended to illustrate the effect of the slip range and the terminal voltage on the power limit curves.Comparison of hybrid analytical modelling and reluctance network modelling for pre-design purposeshttps://zbmath.org/1540.780182024-09-13T18:40:28.020319Z"Ouagued, Sofiane"https://zbmath.org/authors/?q=ai:ouagued.sofiane"Amara, Yacine"https://zbmath.org/authors/?q=ai:amara.yacine"Barakat, Georges"https://zbmath.org/authors/?q=ai:barakat.georgesSummary: The aim of this paper is to compare two modelling approaches, used for the pre-design of electrical machines. A new hybrid analytical modelling (HAM) approach, based on a direct coupling of analytical solution of Maxwell's equations with reluctance networks (RN), is compared to mesh-based generated reluctance networks modelling, in terms of computation time and results quality. In order to assess the quality of results obtained from both models, both approaches are compared to finite element simulations. A permanent magnet linear structure is chosen as a case study. It is shown that the new hybrid analytical model allows to combine advantages of analytical and reluctance networks modelling. As compared to RN, the new approach helps reduce calculation time and gives good results.A stabilized \(P1\) domain decomposition finite element method for time harmonic Maxwell's equationshttps://zbmath.org/1540.780192024-09-13T18:40:28.020319Z"Asadzadeh, M."https://zbmath.org/authors/?q=ai:asadzadeh.mohammad-sina"Beilina, L."https://zbmath.org/authors/?q=ai:beilina.larisaSummary: One way of improving the behavior of finite element schemes for classical, time-dependent Maxwell's equations is to render their hyperbolic character to elliptic form. This paper is devoted to the study of a stabilized linear, domain decomposition, finite element method for the time harmonic Maxwell's equations, in a dual form, obtained through the Laplace transformation in time. The model problem is for the particular case of the dielectric permittivity function which is assumed to be constant in a boundary neighborhood. The discrete problem is coercive in a symmetrized norm, equivalent to the discrete norm of the model problem. This yields discrete stability, which together with continuity guarantees the well-posedness of the discrete problem, cf \textit{D. N. Arnold} et al. [SIAM J. Numer. Anal. 39, No. 5, 1749--1779 (2002; Zbl 1008.65080)], \textit{D. A. Di Pietro} and \textit{A. Ern} [Mathematical aspects of discontinuous Galerkin methods. Berlin: Springer (2012; Zbl 1231.65209)]. The convergence is addressed both in \textit{a priori} and \textit{a posteriori} settings. In the a priori error estimates we confirm the theoretical convergence of the scheme in a \(L_2\)-based, gradient dependent, triple norm. The order of convergence is \(\mathcal{O} (h)\) in weighted Sobolev space \(H_w^2 (\Omega)\), and hence optimal. Here, the weight \(w := w ( \varepsilon, s)\) where \(\varepsilon\) is the dielectric permittivity function and \(s\) is the Laplace transformation variable. We also derive, similar, optimal a posteriori error estimates controlled by a certain, weighted, norm of the residuals of the computed solution over the domain and at the boundary (involving the relevant jump terns) and hence independent of the unknown exact solution. The a posteriori approach is used, e.g. in constructing adaptive algorithms for the computational purposes, which is the subject of a forthcoming paper. Finally, through implementing several numerical examples, we validate the robustness of the proposed scheme.Utilization of CANM for magnetic field calculationhttps://zbmath.org/1540.780202024-09-13T18:40:28.020319Z"Ayrian, E. A."https://zbmath.org/authors/?q=ai:ayrian.e-a"Fedorov, A. V."https://zbmath.org/authors/?q=ai:fedorov.alexey-v|fedorov.andrey-v|fedorov.aleksander-v|fedorov.aleksej-v|fedorov.andrej-v|fedorov.alexandre-vSummary: Iterative schemes based on continuous analogue of the Newton's method have been successfully used in computational modeling of various nonlinear physical problems. The paper concerns the utilization of this method to solve magnetostatic field equations. The extended convergence domain of the method makes possible to construct fast, reliable, robust iteration scheme for magnetic field calculations. Data illustrated convergence of the scheme are presented.
For the entire collection see [Zbl 0863.00040].High-order discontinuous Galerkin method for time-domain electromagnetics on non-conforming hybrid mesheshttps://zbmath.org/1540.780212024-09-13T18:40:28.020319Z"Fahs, Hassan"https://zbmath.org/authors/?q=ai:fahs.hassanSummary: We present a high-order discontinuous Galerkin (DG) method for solving the time-dependent Maxwell equations on non-conforming hybrid meshes. The hybrid mesh combines unstructured tetrahedra for the discretization of irregularly shaped objects with a hexahedral mesh for the rest of the computational domain. The transition between tetrahedra and hexahedra is completely non-conform, that is, no pyramidal or prismatic elements are introduced to link these elements. Within each mesh element, the electromagnetic field components are approximated by a arbitrary order nodal polynomial and a centered approximation is used for the evaluation of numerical fluxes at inter-element boundaries. The time integration of the associated semi-discrete equations is achieved by a fourth-order leap-frog scheme. The method is described and discussed, including algorithm formulation, stability, and practical implementation issues such as the hybrid mesh generation and the computation of flux matrices with cubature rules. We illustrate the performance of the proposed method on several two- and three-dimensional examples involving comparisons with DG methods on single element-type meshes. The results show that the use of non-conforming hybrid meshes in DG methods allows for a notable reduction in computing time without sacrificing accuracy.A finite element model of terahertz substrate-based wire-grid polarizerhttps://zbmath.org/1540.780222024-09-13T18:40:28.020319Z"Jaworski, Nazariy"https://zbmath.org/authors/?q=ai:jaworski.nazariy"Andrushchak, Nazariy"https://zbmath.org/authors/?q=ai:andrushchak.nazariy"Lobur, Mykhailo"https://zbmath.org/authors/?q=ai:lobur.mykhailo"Iwaniec, Marek"https://zbmath.org/authors/?q=ai:iwaniec.marekSummary: Using the finite element approximation of electromagnetic wave propagation problem in frequency domain analysis, we have developed and implemented a finite element model of a terahertz substrate-based wire grid polarizer in a form of unit cell. The proposed polarization unit cell is considered as a waveguide with a specific boundary condition. The model is implemented by the COMSOL software system as a ready to use tool for terahertz polarizers design or refinement. Simulation results show an excellent agreement with known experimental and simulation data.On the proper generalized decomposition applied to microwave processes involving multilayered componentshttps://zbmath.org/1540.780232024-09-13T18:40:28.020319Z"Tertrais, H."https://zbmath.org/authors/?q=ai:tertrais.h"Ibañez, R."https://zbmath.org/authors/?q=ai:ibanez.ruben"Barasinski, A."https://zbmath.org/authors/?q=ai:barasinski.anais"Ghnatios, Ch."https://zbmath.org/authors/?q=ai:ghnatios.chady"Chinesta, F."https://zbmath.org/authors/?q=ai:chinesta.franciscoSummary: Many electrical and structural components are constituted of a stacking of multiple thin layers with different electromagnetic, mechanical and thermal properties. When 3D descriptions become compulsory the approximation of the fields along the thickness direction could involve thousands of nodes. To circumvent the numerical difficulties that such a rich description imply, we recently propose an in-plane-out-of-plane separated representation with the aim of computing fully 3D solutions as a sequence of 2D problems defined in the plane and others (1D) in the thickness. The main contribution of the present work is the proposal of an efficient in-plane-out-of-plane separated representation of the double-curl formulation of Maxwell equations able to address thin-layer laminates while ensuring the continuity and discontinuity of the tangential and normal electric field components respectively at the plies interface.A space-time Trefftz DG scheme for the time-dependent Maxwell equations in anisotropic mediahttps://zbmath.org/1540.780242024-09-13T18:40:28.020319Z"Yuan, Long"https://zbmath.org/authors/?q=ai:yuan.long"Gong, Wenxiu"https://zbmath.org/authors/?q=ai:gong.wenxiuSummary: In this paper we are concerned with Trefftz discretizations of the time-dependent Maxwell equations in anisotropic media in three-dimensional domains. We propose a class of space-time Trefftz DG methods, which include the Trefftz variational formulation from \textit{H. Egger} et al. [SIAM J. Sci. Comput. 37, No. 5, B689--B711 (2015; Zbl 1330.65148)]. We prove the error estimates of the approximate solutions with respect to the meshwidth and the condition number of the coefficient matrices. Furthermore, we propose the global Trefftz DG method combined with local DG methods to solve the time-dependent linear nonhomogeneous Maxwell equations in anisotropic media. The numerical results verify the validity of the theoretical results, and show that the resulting approximate solutions possess high accuracy.Galerkin method for discs capacitorshttps://zbmath.org/1540.780252024-09-13T18:40:28.020319Z"Paffuti, Giampiero"https://zbmath.org/authors/?q=ai:paffuti.giampieroSummary: The physics of nano and micro electro-mechanical systems would benefit from an accurate knowledge of electrostatics forces between electrodes. Quite complicated behaviors can arise and a precise computation of capacity matrices, from which forces can be derived, is required. We develop, for circular thick electrodes, a method based on the Galerkin approximation. Almost all the matrix elements needed are evaluated analytically and consequently high precision results can be obtained. In parallel we provide an implementation of the Boundary Elements Method (BEM) which gives a check of the computations and can be used independently. We test our method on the well studied problem of two flat discs capacitor, obtaining results in excellent agreement with expected asymptotic estimates.A multigrid-based preconditioned solver for the Helmholtz equation with a discretization by 25-point difference schemehttps://zbmath.org/1540.780262024-09-13T18:40:28.020319Z"Cheng, Dongsheng"https://zbmath.org/authors/?q=ai:cheng.dongsheng"Liu, Zhiyong"https://zbmath.org/authors/?q=ai:liu.zhiyong"Wu, Tingting"https://zbmath.org/authors/?q=ai:wu.tingtingSummary: In this paper, a preconditioned iterative method is developed to solve the Helmholtz equation with perfectly matched layer (Helmholtz-PML equation). The complex shifted-Laplacian is generalized to precondition the Helmholtz-PML equation, which is discretized by an optimal 25-point finite difference scheme that we presented in [\textit{Z. Chen} et al., J. Math. Anal. Appl. 383, No. 2, 522--540 (2011; Zbl 1231.65198)]. A spectral analysis is given for the discrete preconditioned system from the perspective of linear fractal mapping, and Bi-CGSTAB is used to solve it. The multigrid method is employed to invert the preconditioner approximately, and a new matrix-based prolongation operator is constructed in the multigrid cycle. Numerical experiments are presented to illustrate the efficiency of the multigrid-based preconditioned Bi-CGSTAB method with the new prolongation operator. Numerical results are also given to compare the performance of the new prolongation operator with that of the prolongation operator based on the algebraic multigrid (AMG) principle.HOC-ADI schemes for two-dimensional Ginzburg-Landau equation in superconductivityhttps://zbmath.org/1540.780272024-09-13T18:40:28.020319Z"Kong, Linghua"https://zbmath.org/authors/?q=ai:kong.linghua"Luo, Yiyang"https://zbmath.org/authors/?q=ai:luo.yiyang"Wang, Lan"https://zbmath.org/authors/?q=ai:wang.lan.1"Chen, Meng"https://zbmath.org/authors/?q=ai:chen.meng.4"Zhao, Zhi"https://zbmath.org/authors/?q=ai:zhao.zhiSummary: In this paper, we apply the high-order compact scheme coupled with alternating direction implicit (HOC-ADI) method to solve the two-dimensional Ginzburg-Landau (2D GL) equation. Five HOC-ADI schemes with second order accuracy in time and fourth order in space are proposed for 2D GL equation. Scheme I and Scheme II are both nonlinear, which need nonlinear iteration.To overcome this shortcoming, Scheme III and Scheme IV are proposed in order to avoid nonlinear iteration. With the three-level ADI scheme and the method of extrapolation, we obtain a linearized scheme V. Some numerical experiments are shown to testify and compare the superiority of the new numerical schemes.The tensor-train mimetic finite difference method for three-dimensional Maxwell's wave propagation equationshttps://zbmath.org/1540.780282024-09-13T18:40:28.020319Z"Manzini, G."https://zbmath.org/authors/?q=ai:manzini.gianmarco"Truong, P. M. D."https://zbmath.org/authors/?q=ai:truong.p-m-d"Vuchkov, R."https://zbmath.org/authors/?q=ai:vuchkov.radoslav-g"Alexandrov, B."https://zbmath.org/authors/?q=ai:alexandrov.boian-sSummary: Coupling the mimetic finite difference method with the tensor-train format results in a very effective method for low-rank numerical approximations of the solutions of the time-dependent Maxwell wave propagation equations in three dimensions. To this end, we discretize the curl operators on the primal/dual tensor product grid complex and we couple the space discretization with a staggered-in-time second-order accurate time-marching scheme. The resulting solver is accurate to the second order in time and space, and still compatible, so that the approximation of the magnetic flux field has zero discrete divergence with a discrepancy close to the machine precision level. Our approach is not limited to the second-order of accuracy. We can devise higher-order formulations in space through suitable extensions of the tensor-train stencil to compute the derivatives of the mimetic differential operators. Employing the tensor-train format improves the solver performance by orders of magnitude in terms of CPU time and memory storage. A final set of numerical experiments confirms this expectation.BCC-grid versus SC-grid in the modeling of a sheet of graphene as a surface boundary condition in the context of ADE-FDTDhttps://zbmath.org/1540.780292024-09-13T18:40:28.020319Z"Moreno, E."https://zbmath.org/authors/?q=ai:camps-moreno.eduardo|moreno.elvira|moreno.e-garcia|moreno.edward-david|moreno.enrique-f|moreno.edna-c|moreno.edgar-j-lopez|moreno.esteban|moreno.elias|moreno.eduardo"González, P."https://zbmath.org/authors/?q=ai:gonzalez.pedro-a|gonzalez.p-r|gonzalez.pedro-henrique|gonzalez.patricia|gonzalez.pablo-a-miranda|gonzalez.pedro-pablo|gonzalez.p-d|gonzalez.pablo-j|gonzalez.patrick|gonzalez.pauline|gonzalez.paulo|gonzalez.p-l|gonzalez.pascual|gonzalez.patricio|gonzalez.paula"Emadi, R."https://zbmath.org/authors/?q=ai:emadi.r"Roldán, J. B."https://zbmath.org/authors/?q=ai:roldan.juan-b"Michael, E. A."https://zbmath.org/authors/?q=ai:michael.e-aSummary: Here, we model a thin layer of graphene located above a metal surface by means of a surface boundary condition in two different stencils, namely, a simple cubic grid (SC-Grid) and a body centered cubic grid (BCC-Grid). We extend the methodology described in the literature by taking into account the interband contribution of the graphene's conductivity in addition to the intraband contribution. The mathematical description of the presented developments is explained. Besides this, the metal in contact with the graphene sheet is considered as a dispersive medium; therefore, we deal with the problem by using the auxiliary differential equation finite-difference time-domain (ADE-FDTD) method. In this context, we compared the two stencils and demonstrated that BCC-Grid does not present discontinuities in the normal components of the electric and magnetic fields located on the graphene surface; in this respect, BCC-Grid is also more appropriate than the traditional Yee's cell for these type of applications.A locally stabilized radial basis function partition of unity technique for the sine-Gordon system in nonlinear opticshttps://zbmath.org/1540.780302024-09-13T18:40:28.020319Z"Nikan, O."https://zbmath.org/authors/?q=ai:nikan.omid"Avazzadeh, Z."https://zbmath.org/authors/?q=ai:avazzadeh.zakiehSummary: This paper develops a localized radial basis function partition of unity method (RBF-PUM) based on a stable algorithm for finding the solution of the sine-Gordon system. This system is one useful description for the propagation of the femtosecond laser optical pulse in a systems of two-level atoms. The proposed strategy approximates the unknown solution through two main steps. First, the time discretization of the problem is accomplished by a difference formulation with second-order accuracy. Second, the space discretization is obtained using the local RBF-PUM. This method authorizes us to tackle the high computational time related to global collocation techniques. However, this scheme has the disadvantage of instability when the shape parameter \(\varepsilon\) approaches to small value. In order to deal with this issue, we adopt RBF-QR scheme that provides the higher accuracy and stable computations for small values \(\varepsilon\). Two examples are presented to show the high accuracy of the method and to compare with other techniques in the literature.Use of reluctance network modelling and software component to study the influence of electrical machine pole number on hybrid electric vehicle global optimizationhttps://zbmath.org/1540.780312024-09-13T18:40:28.020319Z"Guyadec, M. Le"https://zbmath.org/authors/?q=ai:guyadec.m-le"Gerbaud, L."https://zbmath.org/authors/?q=ai:gerbaud.laurent"Vinot, E."https://zbmath.org/authors/?q=ai:vinot.emmanuel"Reinbold, V."https://zbmath.org/authors/?q=ai:reinbold.v"Dumont, C."https://zbmath.org/authors/?q=ai:dumont.cyrielle|dumont.christopheSummary: In the paper, the global optimization of hybrid electric vehicle (HEV) components and control is performed using genetic algorithm and dynamic programming. Reluctance network modelling (RNM) is used to describe the behaviour of the electrical machine (EM). The pole number is considered as a design variable in the EM model. A software component is built from this model and is used in Matlab for a sizing by optimization. The influence of the EM pole number on the system optimization is analysed. Contrary to the low differences observed on the energy efficiency of the vehicle, the machine shape is highly impacted.Structural optimization to maximize the flux control range of a double excitation synchronous machinehttps://zbmath.org/1540.780322024-09-13T18:40:28.020319Z"Hoang, Trung-Kien"https://zbmath.org/authors/?q=ai:hoang.trung-kien"Vido, Lionel"https://zbmath.org/authors/?q=ai:vido.lionel"Gillon, Frederic"https://zbmath.org/authors/?q=ai:gillon.frederic"Gabsi, Mohamed"https://zbmath.org/authors/?q=ai:gabsi.mohamedSummary: This paper deals with a structural optimization to maximize the no-load flux control capability of a double excitation synchronous machine (DESM). The air-gap flux in this machine type can be regulated by controlling the field currents. In this paper, this curve in the no-load condition is referred to as the flux control range (FCR). Maximizing the gap between the minimum-flux and maximizing the maximum-flux points of this curve is targeted to improve the controlling effectiveness of the field windings, and reduce field winding's copper losses. This gap is affected by two factors: the magnetic saturation and thermal limits of the machine. Thermal analyses are rarely focused for the DESM type in the literature. The contribution of this paper is to maximize the FCR gap taking into account the thermal limitation. In addition, a general guide for the DESM design will be also discussed.OpenComp3d: an open-source framework dedicated to design in power electronicshttps://zbmath.org/1540.780332024-09-13T18:40:28.020319Z"Morentin, A."https://zbmath.org/authors/?q=ai:morentin.a"Fontes, G."https://zbmath.org/authors/?q=ai:fontes.guillaume"Hillesheim, M. Mannes"https://zbmath.org/authors/?q=ai:hillesheim.m-mannes"Meynard, T."https://zbmath.org/authors/?q=ai:meynard.t"Flumian, D."https://zbmath.org/authors/?q=ai:flumian.d"Bourdon, J."https://zbmath.org/authors/?q=ai:bourdon.jeremie"Piquet, H."https://zbmath.org/authors/?q=ai:piquet.hubertSummary: This paper is an overview of an innovative optimization framework developed for the design of power converters, which is available under MIT licence in a github repository (\url{https://github.com/Laplace-cs/OpenComp3d}). In the first part, the general principles, structure and standards are presented. In the second part, an example is performed to optimize the output inductor of a buck converter showing the advantages of the proposed methodology.Multi-level integrated optimal design for power systems of more electric aircrafthttps://zbmath.org/1540.780342024-09-13T18:40:28.020319Z"Ounis, H."https://zbmath.org/authors/?q=ai:ounis.hadj|ounis.hadjer"Sareni, B."https://zbmath.org/authors/?q=ai:sareni.bruno"Roboam, X."https://zbmath.org/authors/?q=ai:roboam.xavier"De Andrade, A."https://zbmath.org/authors/?q=ai:de-andrade.agenor-freitas|de-andrade.antonio-aparecido|de-andrade.allan-edley-ramos|de-andrade.alexandreSummary: This paper proposes a multi-level optimal design method for a complex actuation system of more electric aircraft. The multi-level structure consists in sharing the optimization process in several levels, here 2, a ``system level'' which involves main coupling variables and a ``component level'' with one optimization loop for each device. The interest of this method is to separate the optimal design of each component, making easier the convergence of loops. This method is applied to a relatively complex power conversion system including a high speed permanent magnet synchronous machine (HSPMSM) supplied by a pulse width modulation (PWM) voltage source inverter (VSI) associated with a DC-link filter. Its interest is shown through a comparison with classical design approaches employed in previous works.Simultaneous optimization of sizing and energy management -- application to hybrid trainhttps://zbmath.org/1540.780352024-09-13T18:40:28.020319Z"Poline, Marie"https://zbmath.org/authors/?q=ai:poline.marie"Gerbaud, Laurent"https://zbmath.org/authors/?q=ai:gerbaud.laurent"Pouget, Julien"https://zbmath.org/authors/?q=ai:pouget.julien"Chauvet, Frédéric"https://zbmath.org/authors/?q=ai:chauvet.fredericSummary: The increasing railway traffic and the environmental issue demand to find new solutions to provide energy to autonomous train (train with embedded energy sources such as diesel power supply). Using hybrid diesel train with embedded storage elements is an interesting technical solution but this kind of multisource system presents new scientific and methodology challenges. Thus, in the paper, the problematic focus on the design and the energy management of the different sources for this system. Moreover, these two fields are linked to each other. Indeed, there is a strong influence of the sizing on the energy management but the reverse is also true. The paper deals with a new optimization approach to perform the design of both the hybrid sources sizing and their energy management. The multi-sources system is represented by a power flow model and the energy management strategy is based on a frequency approach and on dynamic programming. This direct optimization problem is solved by the Sequential Quadratic Programming (SQP) algorithm. Thus, in the paper, this optimization approach is applied to a real railway study case. A comparison is made between two cases with different energy management methods.On the evaluation of electrostatic energy of volume charge distributions and the role of the Coulomb singularityhttps://zbmath.org/1540.780362024-09-13T18:40:28.020319Z"Stén, Johan C.-E."https://zbmath.org/authors/?q=ai:sten.johan-c-e"Essén, Hanno"https://zbmath.org/authors/?q=ai:essen.hannoSummary: Methods for evaluating electrostatic interaction energy of volume distributions of charge of different shapes and densities are studied. In our numerical method, a cubic integration volume is divided into smaller sub-cubes, whereupon the pertinent double volume integral is turned into a six-fold sum from which all self-interaction terms exhibiting the Coulomb singularity are duly extracted. More precision is gained by optimising the values of the partial integrals corresponding to the nearest interacting sub-cubes obtained by different discretisation of a cube. Further insight is obtained by modelling a sphere, a cylinder and a cube with cubical elements, for which analytical results are available. We also consider spheres with different radially dependent charge density functions, whose interaction energy is known exactly.Solution of the equilibrium problem in electromagnetic casting considering a solid inclusion in the melthttps://zbmath.org/1540.800092024-09-13T18:40:28.020319Z"Canelas, Alfredo"https://zbmath.org/authors/?q=ai:canelas.alfredo"Pereira, Antonio"https://zbmath.org/authors/?q=ai:pereira.antonio-luiz|pereira.antonio-d|pereira.antonio"Roche, Jean R."https://zbmath.org/authors/?q=ai:roche.jean-rodolphe"Brancher, Jean P."https://zbmath.org/authors/?q=ai:brancher.jean-pierreSummary: A new method is proposed for solving the equilibrium problem related to the electromagnetic casting technique. The method is appropriate for the case when part of the metal is in solid state. It is shown that in the presence of solid inclusions the equilibrium equation of the free liquid boundary can be formulated as a complementarity equation. A Newton-like iteration is then proposed to solve the resulting set of nonlinear equations. Results for some numerical examples are presented, showing that in the case of simple configurations the numerical technique proposed finds solutions in good agreement with the analytical solutions presented in the literature. Examples of more complex situations with solid inclusions represented by level set functions are also solved, showing that the proposed algorithm can be reliably used to find equilibrium configurations.Quantum steering vs entanglement and extracting work in an anisotropic two-qubit Heisenberg model in presence of external magnetic fields with DM and KSEA interactionshttps://zbmath.org/1540.810212024-09-13T18:40:28.020319Z"Amazioug, M."https://zbmath.org/authors/?q=ai:amazioug.mohamed"Daoud, M."https://zbmath.org/authors/?q=ai:daoud.mohammedSummary: We examine the Dzyaloshinski-Moriya (DM) and Kaplan-Shekhtman-Entin-Wohlman-Aharony (KSEA) interactions in thermal equilibrium submitted to the anisotropic Heisenberg two-qubit model in an inhomogeneous magnetic field. The steerability between the two qubits is evaluated using quantum steering. The concurrence serves as a witness to quantum entanglement. Both the extracted work and the ideal efficiency of the two qubits are quantified. We discuss how quantum correlations behave in relation to the bath's temperature, the Kaplan-Shekhtman-Entin-Wohlman-Aharony coupling parameter and DM coupling. We find that the nonclassical correlations in a two-qubit Heisenberg XYZ Model are fragile under thermal effects. Nevertheless, the results indicate that the concurrence is stronger than quantum steering under thermal effects in the presence of DM and KSEA. We obtained that an extraction of work is comparable with the bare energies.Generation of microwave-optics entanglement via reservoir engineering in cavity magnonic systemshttps://zbmath.org/1540.810292024-09-13T18:40:28.020319Z"Shang, Xiao"https://zbmath.org/authors/?q=ai:shang.xiao"Chen, Dan-Dan"https://zbmath.org/authors/?q=ai:chen.dandan"Xie, Hong"https://zbmath.org/authors/?q=ai:xie.hong"Lin, Gong-Wei"https://zbmath.org/authors/?q=ai:lin.gongwei"Lin, Xiu-Min"https://zbmath.org/authors/?q=ai:lin.xiu-minSummary: The strong microwave-optics entanglement is generated based on a cavity magnonic hybrid quantum system, where the magnon mode couples to the microwave cavity mode via magnetic dipole interaction and interacts with the optical modes via magneto-optical effects. It is shown that the microwave-optics entanglement can be achieved by the intermediate magnon mode acting as an engineered reservoir to cool the Bogoliubov mode, which consists of an optical mode and a microwave cavity mode. By optimizing the ratio of effective couplings and the dissipation of the magnon mode, the strong microwave-optics entanglement is obtained, which is far larger than that based on the coherent parametric coupling. The microwave-optics entanglement created in our model is that between microwave mode and polarized optical mode. Such entanglement which involves the degrees of freedom of polarization may have potential applications in polarization-dependent quantum information tasks.Effects of Josephson junction synapse on coupled Morris-Lecar neuronshttps://zbmath.org/1540.810382024-09-13T18:40:28.020319Z"Ramakrishnan, Balamurali"https://zbmath.org/authors/?q=ai:ramakrishnan.balamurali"Natiq, Hayder"https://zbmath.org/authors/?q=ai:natiq.hayder"Parastesh, Fatemeh"https://zbmath.org/authors/?q=ai:parastesh.fatemeh"Rajagopal, Karthikeyan"https://zbmath.org/authors/?q=ai:rajagopal.karthikeyan"Jafari, Sajad"https://zbmath.org/authors/?q=ai:jafari.sajadSummary: Recently, various artificial synapses have been examined in neural networks for obtaining different dynamical characteristics of neurons. The Josephson junction can be used for constructing an artificial synapse that incorporates the external magnetic field effects. Using the Josephson junction for coupling the neurons involves the phase error between the junctions. This paper uses the Josephson junction and a linear resistor to connect two Morris-Lecar neuron models. The effects of Josephson junction parameters are investigated on the dynamical properties of neurons. The obtained bifurcation and Lyapunov exponent diagrams represent that the Josephson junction synapse significantly affects the neurons' dynamics. Rich dynamics are observed by varying the junction parameters. Moreover, the multistability properties are reported. Finally, the synchronization of coupled neurons is studied under different junction's parameters.Fredholm property of interaction problems on unbounded \(C^2-\) hypersurfaces in \(\mathbb{R}^n\) for Dirac operatorshttps://zbmath.org/1540.810522024-09-13T18:40:28.020319Z"Rabinovich, Vladimir S."https://zbmath.org/authors/?q=ai:rabinovich.vladimir-sSummary: We consider the Dirac operators on \(\mathbb{R}^n\), \(n\ge 2\) with singular potentials
\[
\begin{aligned}
D_{\mathbf{A},\Phi ,m,\Gamma \delta_\Sigma}=\mathfrak{D}_{A,\Phi ,m}+\Gamma \delta_\Sigma
\end{aligned}\tag{1}
\]
where
\[
\begin{aligned}
\mathfrak{D}_{\mathbf{A},\Phi ,m}=\sum \limits_{j=1}^n\alpha_j\left( -i\partial_{x_j}+A_j\right) +\alpha_{n+1}m+\Phi I_N
\end{aligned} \tag{2}
\]
is a Dirac operator on \(\mathbb{R}^n\) with the variable magnetic and electrostatic potentials \(A\mathbf{=}(A_1,\dots,A_n)\) and \(\Phi \), and the variable mass \(m\). In formula (2) \(\alpha_j\) are the \(N\times N\) Dirac matrices, that is \(\alpha_j\alpha_k+\alpha_k\alpha_j=2\delta_{jk}\mathbb{I}_N\), \(\mathbb{I}_N\) is the unit \(N\times N\) matrix, \(N=2^{\left[ \left( n+1\right) /2\right] },\Gamma \delta_{\Sigma }\) is a singular delta-type potential supported on a uniformly regular unbounded \(C^2-\) hypersurface \(\Sigma \subset \mathbb{R}^n\) being the common boundary of the open sets \(\Omega_{\pm } \). Let \(H^1(\Omega^{\pm },\mathbb{C}^N)\) be the Sobolev spaces of \(N-\) dimensional vector-valued distributions \(\mathbf{u}\) on \(\Omega^{\pm },\) and
\[
\begin{aligned}
H^1(\mathbb{R}^n\diagdown \Sigma ,\mathbb{C}^N)=H^1(\Omega_+,\mathbb{C}^N)\oplus H^1(\Omega_-,\mathbb{C}^N).
\end{aligned}
\]
We associate with the formal Dirac operator \(D_{A,\Phi ,m,\Gamma \delta_\Sigma}\) the interaction (transmission) operator \(\mathbb{D}_{A,\Phi ,m,B_{\Sigma }}=\left( \mathfrak{D}_{A,\Phi ,m},\mathfrak{B}_{\Sigma }\right)\) defined by the Dirac operator \(\mathfrak{D}_{\mathbf{A},\Phi ,m}\) on \(H^1(\mathbb{R}^n\diagdown \Sigma ,\mathbb{C}^N)\) and the interaction condition \(\mathfrak{B}_{\Sigma }:H^1(\mathbb{R}^n\mathbb{B}_{A,m},\Phi,\mathfrak{B}_{\Sigma}, \mathbb{C}^N)\rightarrow H^{1/2}(\Sigma ,\mathbb{C}^N)\) associated with the singular potential. The main goal of the paper is to study the Fredholm property of the operators \(\mathbb{D}_{A,\Phi ,m,\mathfrak{B}_{\Sigma }}\) for some non-compact \(C^2 \)-hypersurfaces.Dissipative light bullets in a doped and weakly nonlocal optical fiberhttps://zbmath.org/1540.810632024-09-13T18:40:28.020319Z"Ngon, Ghislaine Flore Kabadiang"https://zbmath.org/authors/?q=ai:ngon.ghislaine-flore-kabadiang"Tabi, Conrad Bertrand"https://zbmath.org/authors/?q=ai:tabi.conrad-bertrand"Kofané, Timoléon Crépin"https://zbmath.org/authors/?q=ai:kofane.timoleon-crepinSummary: The letter introduces an extended (3+1)-dimensional [(3+1)D] nonlocal cubic complex Ginzburg-Landau equation describing the dynamics of dissipative light bullets in optical fiber amplifiers under the interplay between dopants and a spatially nonlocal nonlinear response. The model equation includes the effects of fiber dispersion, linear gain, nonlinear loss, fiber nonlinearity, atomic detuning, linear and nonlinear diffractive transverse effects, and nonlocal nonlinear response. A system of coupled ordinary differential equations for the amplitude, temporal, and spatial pulse widths and position of the pulse maximum, unequal wavefront curvatures, chirp parameters, and phase shift is derived using the variational technique. A stability criterion is established, where a domain of dissipative parameters for stable steady-state solutions is found. Direct integration of the proposed nonlocal evolution equation is performed, which allows us to investigate the evolution of the Gaussian beam along a doped nonlocal optical fiber, showing stable self-organized dissipative spatiotemporal light bullets.A nontopological soliton in an \(\mathcal{N} = 1\) supersymmetric abelian gauge modelhttps://zbmath.org/1540.810652024-09-13T18:40:28.020319Z"Loginov, A. Yu."https://zbmath.org/authors/?q=ai:loginov.a-yuSummary: A version of \(\mathcal{N} = 1\) supersymmetric scalar electrodynamics is considered here, and it is shown that an electrically charged nontopological soliton exists in this model. In addition to the long-range electric field, the soliton also possesses a long-range scalar field, which leads to a modification of the intersoliton interaction potential at large distances. The supersymmetry of the model makes it possible to express fermionic zero modes of the soliton in terms of bosonic fields. The properties of the nontopological soliton are investigated using analytical and numerical methods.\(\mathfrak{gl}(3)\) polynomial integrable system: different faces of the 3-body/\(\mathcal{A}_2\) elliptic Calogero modelhttps://zbmath.org/1540.810712024-09-13T18:40:28.020319Z"Turbiner, Alexander V."https://zbmath.org/authors/?q=ai:turbiner.alexander"Lopez Vieyra, Juan Carlos"https://zbmath.org/authors/?q=ai:lopez-vieyra.juan-carlos"Guadarrama-Ayala, Miguel A."https://zbmath.org/authors/?q=ai:guadarrama-ayala.miguel-aSummary: It is shown that the \(\mathfrak{gl}(3)\) polynomial integrable system, introduced by \textit{V. V. Sokolov} and \textit{A. V. Turbiner} in [J. Phys. A, Math. Theor. 48, No. 15, Article ID 155201, 15 p. (2015; Zbl 1329.81434)], is equivalent to the \(\mathfrak{gl}(3)\) quantum Euler-Arnold top in a constant magnetic field. Their Hamiltonian as well as their third-order integral can be rewritten in terms of \(\mathfrak{gl}(3)\) algebra generators. In turn, all these \(\mathfrak{gl}(3)\) generators can be represented by the non-linear elements of the universal enveloping algebra of the 5-dimensional Heisenberg algebra \(\mathfrak{h}_5(\hat{p}_{1,2},\hat{q}_{1,2}, I)\), thus, the Hamiltonian and integral are two elements of the universal enveloping algebra \(U_{\mathfrak{h}_5}\). In this paper, four different representations of the \(\mathfrak{h}_5\) Heisenberg algebra are used: (I) by differential operators in two real (complex) variables, (II) by finite-difference operators on uniform or exponential lattices. We discovered the existence of two 2-parametric bilinear and trilinear elements (denoted \(H\) and \(I\), respectively) of the universal enveloping algebra \(U(\mathfrak{gl}(3))\) such that their Lie bracket (commutator) can be written as a linear superposition of nine so-called artifacts - the special bilinear elements of \(U(\mathfrak{gl}(3))\), which vanish once the representation of the \(\mathfrak{gl}(3)\)-algebra generators is written in terms of the \(\mathfrak{h}_5(\hat{p}_{1,2},\hat{q}_{1,2}, I)\)-algebra generators. In this representation all nine artifacts vanish, two of the above-mentioned elements of \(U(\mathfrak{gl}(3))\) (called the Hamiltonian \(H\) and the integral \(I)\) commute(!); in particular, they become the Hamiltonian and the integral of the 3-body elliptic Calogero model, if \((\hat{p},\hat{q})\) are written in the standard coordinate-momentum representation. If \((\hat{p},\hat{q})\) are represented by finite-difference/discrete operators on uniform or exponential lattice, the Hamiltonian and the integral of the 3-body elliptic Calogero model become the isospectral, finite-difference operators on uniform-uniform or exponential-exponential lattices (or mixed) with polynomial coefficients. If \((\hat{p},\hat{q})\) are written in complex \((z, \bar{z})\) variables the Hamiltonian corresponds to a complexification of the 3-body elliptic Calogero model on \(\mathbb{C}^2\).Kinematical waves in spacetimehttps://zbmath.org/1540.810752024-09-13T18:40:28.020319Z"Garat, Alcides"https://zbmath.org/authors/?q=ai:garat.alcidesSummary: We will prove how to create kinematical waves in spacetime. To this end we will combine the newfound technique to change locally the electromagnetic gauge in Minkowski spacetimes by using ideal solenoids and the Aharonov-Bohm effect. The local kinematical states of spacetime represented by a new kind of local tetrad will be made to oscillate according to preestablished wave equations and we will show how to produce these effects from a mathematical point of view and from a technological point of view. Kinematical waves just to mention one possible application could be used for communication.Polar coherent states in bilayer graphene under a constant uniform magnetic fieldhttps://zbmath.org/1540.810772024-09-13T18:40:28.020319Z"Martínez-Moreno, D. I."https://zbmath.org/authors/?q=ai:martinez-moreno.dennis-i"Negro, J."https://zbmath.org/authors/?q=ai:negro.javier"Nieto, L. M."https://zbmath.org/authors/?q=ai:nieto.luis-miguelSummary: In this work, the interaction of the electrons in bilayer graphene with a constant, homogeneous magnetic field perpendicular to its surface is analyzed. A symmetric gauge is used for the electromagnetic vector potential, which leads to the use of polar coordinates. The symmetries associated with the Hamiltonian that describes this system are applied to explain some fundamental properties, such as the spectrum and the integer pseudo-spin character of the eigenfunctions. The current densities associated with the bilayer Hamiltonian have been calculated in both Cartesian and polar coordinates showing that they are gauge invariant. Additionally, the appropriate coherent states of this system have been derived as eigenstates of a suitable annihilation operator with complex eigenvalues. The local current densities of these coherent states have been calculated, revealing a type of radial component interference effect that has been overlooked until now. Some of these newly presented results are illustrated graphically.A new perspective on quantum field theory revealing possible existence of another kind of fermions forming dark matterhttps://zbmath.org/1540.810882024-09-13T18:40:28.020319Z"Pavšič, Matej"https://zbmath.org/authors/?q=ai:pavsic.matejSummary: Quantum fields are considered as generators of infinite-dimensional Clifford algebra \(\mathrm{Cl}(\infty)\), which can be either orthogonal (in the case of fermions) or symplectic (in the case of bosons). A generic quantum state can be expressed as a superposition of the basis elements of \(\mathrm{Cl}(\infty)\), with the superposition coefficients being multiparticle complex-valued wavefunctions. The basis elements, that are products of the generators of \(\mathrm{Cl}(\infty)\) in the Witt basis, act as creation and annihilation operators. They create positive and negative energy states that include the bare and the Dirac vacuum as special cases. It is shown that the nonvanishing electric charge arises from an extra dimension or from doubling the number of creation and annihilation operators, which brings an extra imaginary unit \(\bar{i}\) into the description. A further extension is to consider \(\bar{i}\) as one of the quaternionic imaginary units and consider a generic state as having values in the quaternionic algebra or, equivalently, in the complexified two-dimensional Clifford algebra, \(\mathrm{Cl}(2)\otimes C\). It contains two distinct fundamental representations of SU(2), one associated with the weak isospin doublet \((\nu_e, e^-)\) and the other one with the doublet of new leptons, denoted by \((\epsilon^+, \nu_\epsilon)\), that together with the new quarks \((u^\prime, d^\prime)\) can be identified with dark matter.Infraparticle states in the massless Nelson model: revisitedhttps://zbmath.org/1540.811582024-09-13T18:40:28.020319Z"Beaud, Vincent"https://zbmath.org/authors/?q=ai:beaud.vincent"Dybalski, Wojciech"https://zbmath.org/authors/?q=ai:dybalski.wojciech"Graf, Gian Michele"https://zbmath.org/authors/?q=ai:graf.gian-micheleSummary: We provide a new construction of infraparticle states in the massless Nelson model. The approximating sequence of our infraparticle state does not involve any infrared cut-offs. Its derivative w.r.t. the time parameter \(t\) is given by a simple explicit formula. The convergence of this sequence as \(t\rightarrow \infty\) to a nonzero limit is then obtained by the Cook method combined with stationary phase estimates. To apply the latter technique, we exploit recent results on regularity of ground states in the massless Nelson model, which hold in the low coupling regime.Collinearly enhanced realizations of the Yennie-Frautschi-Suura (YFS) MC approach to precision resummation theoryhttps://zbmath.org/1540.811602024-09-13T18:40:28.020319Z"Jadach, S."https://zbmath.org/authors/?q=ai:jadach.stanislaw"Ward, B. F. L."https://zbmath.org/authors/?q=ai:ward.bennie-f-l"Was, Z."https://zbmath.org/authors/?q=ai:was.zbigniewSummary: We extend the Yennie-Frautschi-Suura (YFS) IR resummation theory to include all of the attendant collinear contributions which exponentiate. This improves the original YFS formulation in which only a part of these contributions was exponentiated. We show that the new resummed contributions agree with known results from the collinear factorization approach and we argue that they improve the attendant precision tag for a given level of exactness in the respective YFS hard radiation residuals.Nonlinear electrodynamics without singularitieshttps://zbmath.org/1540.811732024-09-13T18:40:28.020319Z"Kruglov, S. I."https://zbmath.org/authors/?q=ai:kruglov.sergey-ilichSummary: Nonlinear electrodynamics with two parameters is studied. It is shown that singularities of point-like electric charges are absent and the electromagnetic energy is finite. Corrections to Coulomb's law are found. The finite static electric field energy of a point-like charge is calculated. We demonstrate that the electron mass may have the electromagnetic nature. It was shown that principles of causality and unitarity take place.Nonlinear electrodynamics without birefringencehttps://zbmath.org/1540.811752024-09-13T18:40:28.020319Z"Russo, Jorge G."https://zbmath.org/authors/?q=ai:russo.jorge-g"Townsend, Paul K."https://zbmath.org/authors/?q=ai:townsend.paul-kingsleySummary: All solutions of the no-birefringence conditions for nonlinear electrodynamics are found. In addition to the known Born-Infeld and Plebanski cases, we find a ``reverse Born-Infeld'' case, which has a limit to Plebanski, and an ``extreme-Born-Infeld'' case, which arises as a Lagrangian constraint. Only Born-Infeld has a weak-field limit, and only Born-Infeld and extreme-Born-Infeld avoid superluminal propagation in constant electromagnetic backgrounds, but all cases have a conformal strong-field limit that coincides with the strong-field limit of Born-Infeld found by \textit{I. Bialynicki-Birula} [``Nonlinear Electrodynamics: Variations on a theme by Born and Infeld'', in: Quantum Theory of Particles and Fields, World Scientific (1983)].Inhomogeneous conformal field theory out of equilibriumhttps://zbmath.org/1540.811882024-09-13T18:40:28.020319Z"Moosavi, Per"https://zbmath.org/authors/?q=ai:moosavi.perSummary: We study the non-equilibrium dynamics of conformal field theory (CFT) in \(1+1\) dimensions with a smooth position-dependent velocity \(v(x)\) explicitly breaking translation invariance. Such inhomogeneous CFT is argued to effectively describe \(1+1\)-dimensional quantum many-body systems with certain inhomogeneities varying on mesoscopic scales. Both heat and charge transport are studied, where, for concreteness, we suppose that our CFT has a conserved \(\mathrm{U}(1)\) current. Based on projective unitary representations of diffeomorphisms and smooth maps in Minkowskian CFT, we obtain a recipe for computing the exact non-equilibrium dynamics in inhomogeneous CFT when evolving from initial states defined by smooth inverse-temperature and chemical-potential profiles \(\beta (x)\) and \(\mu (x)\). Using this recipe, the following exact analytical results are obtained: (i) the full time evolution of densities and currents for heat and charge transport, (ii) correlation functions for components of the energy-momentum tensor and the \(\mathrm{U}(1)\) current as well as for any primary field, and (iii) the thermal and electrical conductivities. The latter are computed by direct dynamical considerations and alternatively using a Green-Kubo formula. Both give the same explicit expressions for the conductivities, which reveal how inhomogeneous dynamics opens up the possibility for diffusion as well as implies a generalization of the Wiedemann-Franz law to finite times within CFT.Quantum simulation and Anderson localization in vector rogue waves of Bose-Einstein condensatehttps://zbmath.org/1540.811942024-09-13T18:40:28.020319Z"Kundu, Nilanjan"https://zbmath.org/authors/?q=ai:kundu.nilanjan"Sau, Vicky"https://zbmath.org/authors/?q=ai:sau.vicky"Ghosh, Suranjana"https://zbmath.org/authors/?q=ai:ghosh.suranjana"Roy, Utpal"https://zbmath.org/authors/?q=ai:roy.utpalSummary: We report the existence of vector rogue waves in a coupled Bose-Einstein condensate, trapped in a bichromatic optical lattice, which is an appropriate platform for quantum simulation. Such two-component Bose-Einstein condensate plays a vital role to beget hybrid mixtures and structural transition of nonlinear excitations like rogue waves and solitons. An efficient manipulation of rogue waves is embraced, where we identify the slowing down and stopping of dark rogue wave by lattice engineering. This may nurture quantum memory application and transform the rogue wave mixture immiscible. The existence of Anderson localized rogue wave at the central frustrated lattice site is confirmed by showing the exponential nature and localization length of the condensate. A merging of a dual Anderson rogue waves is manifested in their coherent control. Numerical stability analysis is also carried out for a wide range of trap parameters for experimental viability.Cogging torque reduction of permanent magnet synchronous motor using multi-objective optimizationhttps://zbmath.org/1540.902502024-09-13T18:40:28.020319Z"Ilka, Reza"https://zbmath.org/authors/?q=ai:ilka.reza"Alinejad-Beromi, Yousef"https://zbmath.org/authors/?q=ai:alinejad-beromi.yousef"Yaghobi, Hamid"https://zbmath.org/authors/?q=ai:yaghobi.hamidSummary: Cogging torque is an important issue in design of permanent magnet motors, especially in certain high accuracy applications. Most of the methods utilized for cogging torque reduction lead to motor structure complexity, increasing manufacturing cost and also influencing the output torque. This research tries to find an optimal solution set of the PMSM with the aim of reducing the cogging torque while the output torque is not affected. For this purpose, multi-objective optimization is a proper and reliable approach which can provide the solution set involving conflicting functions simultaneously. Multi-objective optimization determines the logical range of cogging torque reduction with respect to the output torque. In this paper, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II), which is a powerful and well-known multi-objective optimization method, is applied to find the optimal design of a surface-mounted Permanent Magnet Synchronous Motor (PMSM). Simulation results show efficacy of the NSGA-II. In the suggested design solutions that are selected from the Pareto-optimal set, cogging torque is reduced considerably while the output torque has experienced a slight decrease with respect to the nominal value. At last, time-stepping Finite-element Analysis (FEA) is used to validate the multi-objective optimization.A mathematical model for the corneal transparency problemhttps://zbmath.org/1540.920432024-09-13T18:40:28.020319Z"Araújo, Adérito"https://zbmath.org/authors/?q=ai:araujo.aderito"Barbeiro, Sílvia"https://zbmath.org/authors/?q=ai:barbeiro.silvia"Bernardes, Rui"https://zbmath.org/authors/?q=ai:bernardes.rui"Morgado, Miguel"https://zbmath.org/authors/?q=ai:morgado.miguel"Sakić, Sunčica"https://zbmath.org/authors/?q=ai:sakic.suncica(no abstract)