A Structural Analysis of Field/Circuit Coupled Problems Based on a Generalised Circuit Element

In some applications there arises the need of a spatially distributed description of a physical quantity inside a device coupled to a circuit. Then, the in-space discretised system of partial differential equations is coupled to the system of equations describing the circuit (Modified Nodal Analysis) which yields a system of Differential Algebraic Equations (DAEs). This paper deals with the differential index analysis of such coupled systems. For that, a new generalised inductance-like element is defined. The index of the DAEs obtained from a circuit containing such an element is then related to the topological characteristics of the circuit's underlying graph. Field/circuit coupling is performed when circuits are simulated containing elements described by Maxwell's equations. The index of such systems with two different types of magnetoquasistatic formulations (A* and T-$\Omega$) is then deduced by showing that the spatial discretisations in both cases lead to an inductance-like element

Reduced Order Modelling for the Simulation of Quenches in Superconducting Magnets

This contributions discusses the simulation of magnetothermal effects in superconducting magnets as used in particle accelerators. An iterative coupling scheme using reduced order models between a magnetothermal partial differential model and an electrical lumped-element circuit is demonstrated. The multiphysics, multirate and multiscale problem requires a consistent formulation and framework to tackle the challenging transient effects occurring at both system and device level

Long living carriers in a strong electron-phonon interacting two-dimensional doped semiconductor

Carrier doping by the electric field effect has emerged recently as an ideal route for monitoring many-body physics in two-dimensional (2D) materials where the Fermi level is tuned in a way that -- indirectly -- the strength of the interactions can also be scanned. The possibility of systematic doping in combination with high resolution photoemission has allowed to uncover a genuinely many-body electron spectrum in single-layer MoS2 transition metal dichalcogenide, resolving three clear quasi-particle states, where only one state should be expected if the electron-phonon interaction vanished. Our analysis combines first-principles and consistent complex plane analytic approaches and brings into light the presence and the physical origin of two gaps and the three quasi-particle bands which are unambiguously present in the photoemission spectrum. One of these states, though being strongly interacting with the accompanying virtual phonon cloud, presents a notably long lifetime which is an appealing property when trying to understand and take advantage of many-body interactions to modulate the transport properties.Comment: Editorially accepted for publication in "Communications Physics" (14 pages, 3 figures

Programes 3D en l'aprenentatge de Cicles Formatius de la família de Tèxtil, confecció i pell. Estudi d'implementació i viabilitat

Les noves tecnologies cada cop estan més presents i treballar amb programes 3D de moda resultaria interessant i útil per l'alumnat dels cicles formatius de la família de Tèxtil, confecció i pell. L'objectiu d'aquest estudi és investigar l'ús de programes 3D de moda en aquests cicles formatius en centres catalans, i valorar l'interès i la viabilitat que podria tenir la incorporació d'aquest tipus de programes per a complementar l'aprenentatge en aquests cicles en els centres d'estudi. Es tracta d'un estudi quantitatiu transversal. Es va entrevistar a professorat i alumnat de dos centres catalans amb aquest tipus d'estudis, seleccionats per conveniència, mitjançant uns qüestionaris estructurats autoemplenats enviats per correu electrònic a través d'un enllaç. Els participants van manifestar tenir un interès i una necessitat en la implementació d'aquest tipus de programes, a més de considerar-la viable. A partir dels resultats obtinguts, es considera necessària i viable la implementació de programes 3D de tèxtil i moda en l'aprenentatge dels cicles formatius de la família de Tèxtil, confecció i pell. Altrament, es podria dur a terme en qualsevol dels grups d'aquests cicles, preferentment als graus superiors, assenyalant CLO 3D com a programa més adient

Index-aware learning of circuits

Electrical circuits are present in a variety of technologies, making their design an important part of computer aided engineering. The growing number of tunable parameters that affect the final design leads to a need for new approaches of quantifying their impact. Machine learning may play a key role in this regard, however current approaches often make suboptimal use of existing knowledge about the system at hand. In terms of circuits, their description via modified nodal analysis is well-understood. This particular formulation leads to systems of differential-algebraic equations (DAEs) which bring with them a number of peculiarities, e.g. hidden constraints that the solution needs to fulfill. We aim to use the recently introduced dissection concept for DAEs that can decouple a given system into ordinary differential equations, only depending on differential variables, and purely algebraic equations that describe the relations between differential and algebraic variables. The idea then is to only learn the differential variables and reconstruct the algebraic ones using the relations from the decoupling. This approach guarantees that the algebraic constraints are fulfilled up to the accuracy of the nonlinear system solver, which represents the main benefit highlighted in this article.Comment: 15 pages, 15 figure

MONA — A magnetic oriented nodal analysis for electric circuits

The modified nodal analysis (MNA) is probably the most widely used formulation for the modeling and simulation of electric circuits. Its conventional form uses electric node potentials and currents across inductors and voltage sources as unknowns, thus taking an electric viewpoint. In this paper, we propose an alternative magnetic oriented nodal analysis (MONA) for electric circuits, which is based on magnetic node potentials and charges across capacitors and voltage sources as the primary degrees of freedom, thus giving direct access to these quantities. The resulting system has the structure of a generalized gradient system which immediately ensures passivity in the absence of sources. A complete index analysis is presented showing regularity of the magnetic oriented formulation under standard topological conditions on the network interconnection. In comparison to conventional MNA, the differential‐algebraic index of MONA is smaller by one in most cases which facilitates the numerical solution. Some preliminary numerical experiments are presented for illustration of the feasibility and stability of the new approach