Examinando por Autor "Arrayás, Manuel"

Mostrando 1 - 7 de 7

A new paradigm for the dynamics of the early Universe
(IOP Publishing, 2019-11-20) Tucker, Robin W.; Walton, Timothy J.; Arrayás, Manuel; Trueba, José Luis
This paper invokes a new mechanism for reducing a coupled system of fields (including Einstein's equations without a cosmological constant) to equations that possess solutions exhibiting characteristics of immediate relevance to current observational astronomy. Our approach is formulated as a classical Einstein-vector-scalar-Maxwell-fluid field theory on a spacetime with three-sphere spatial sections. Analytic cosmological solutions are found using local charts familiar from standard LFRW cosmological models. These solutions can be used to describe different types of evolution for the metric scale factor, the Hubble, jerk and de-acceleration functions, the scalar spacetime curvature and the Kretschmann invariant constructed from the Riemann–Christoffel spacetime curvature tensor. The cosmological sector of the theory accommodates a particular single big-bang scenario followed by an eternal exponential acceleration of the scale factor. Such a solution does not require an externally prescribed fluid equation of state and leads to a number of new predictions including a current value of the 'jerk' parameter, 'Hopfian-like' source-free Maxwell field configurations with magnetic helicity and distributional 'bi-polar' solutions exhibiting a new charge conjugation symmetry. An approximate scheme for field perturbations about this particular cosmology is explored and its consequences for a thermalisation process and a thermal history are derived, leading to a prediction of the time interval between the big-bang and the decoupling era. Finally it is shown that field couplings exist where both vector and scalar localised linearised perturbations exhibit dispersive wave-packet behaviours. The scalar perturbation may also give rise to Yukawa solutions associated with a massive Klein–Gordon particle. It is argued that the vector and scalar fields may offer candidates for 'dark-energy' and 'dark-matter' respectively.
Design of a system for controlling a levitating sphere in superfluid 3He at extremely low temperatures
(Springer Nature, 2021-10-08) Arrayás, Manuel; Trueba, José Luis; Uriarte, Carlos; Zmeev, Dmitry E.
We present a new mechanical probe to study the properties of superfluid 3He at microkelvin temperatures down to 100 μK. The setup consists of a set of coils for levitating a superconducting sphere and controlling its motion in a wide variety of regimes. In particular, the realisation of motion of a levitating body at a uniform velocity presents both an experimental challenge and a promising direction into the study of the edge states in topological superfluid 3He-B. We include the theoretical study of the device stability and simulations to illustrate the capabilities of the control system.
Empirical Evidence and Mathematical Modelling of Carbamazepine Degradative Kinetics by a Wood‑Rotting Microbial Consortium
(Waste and Biomass Valorization, 2021-04-01) González-Benítez, Natalia; Molina, María del Carmen; Arrayás, Manuel
An experimental evolution system with a wood-rotting microbial consortium (BOS08) has demonstrated the acquisition of a new ability to exploit a previously untapped carbon source, such as the recalcitrant carbamazepine (CBZ). The improved extraction method has provided an accurate CBZ depletion rate from BOS08 of 2.14 ± 0.42 × 10−3 h −1. The consortium did not use cometabolism to process CBZ and the intermediate metabolite produced 10,11-dihydroxycarbamazepine was not pharmacologically active and toxic. The bacteria identification by massive sequencing (Illumina) confirmed the dominance of Proteobacteria Phylum such as genera Cupriavidus sp., Sphingomonas sp., Delftia sp., Acinetobacter sp. and Methylo- bacterium sp. coexisting through all biodegradation process. Based on biological principles, we model the consortium-CBZ kinetics with a set of nonlinear ordinary differential equations with logistic growth type terms. The use of experimental data combined with logistic growth models allow us to test new functional features acquired by the consortium
Machine learning techniques in magnetic levitation problems
(Elsevier, 2022) Arrayás, Manuel; Trueba, José L.; Uriarte, Carlos
We present a method for calculating the stability region of a perfect diamagnet levitated in a magnetic field created by a circular current loop making use of the machine learning techniques. As an application we compute stability regions, points of stable equilibrium and stable oscillatory motions in two chip-based superconducting trap architectures used to levitate superconducting particles. Our procedure is an alternative to a full numerical scheme based on finite element methods which are expensive to implement for optimizing experimental parameters.
Null Electromagnetic Fields from Dilatation and Rotation Transformations of the Hopfion
(MDPI, 2019-09-02) Arrayás, Manuel; Fernández-Rañada, Antonio; Tiemblo, Alfredo; Trueba, José Luis
The application of topology concepts to Maxwell equations has led to the developing of the whole area of electromagnetic knots. In this paper, we apply some symmetry transformations to a particular electromagnetic knot, the hopfion field, to get a new set of knotted solutions with the properties of being null. The new fields are obtained by a homothetic transformation (dilatation) and a rotation of the hopfion, and we study the constraints that the transformations must fulfill in order to generate valid electromagnetic fields propagating in a vacuum. We make use of the Bateman construction and calculate the four-potentials and the electromagnetic helicities. It is observed that the topology of the field lines does not seem to be conserved as it is for the hopfion.
Progress on Levitating a Sphere in Cryogenic Fluids
(Springer Nature, 2023-02-04) Arrayás, Manuel; Bettsworth, Francis; Haley, Richard P.; Schanen, Roch; Trueba, José Luis; Uriarte, Carlos; Zavjalov, Vladislav; Zmeev, Dmitry E.
We present the working prototype of a levitation system designed for investigation of flows in cryogenic helium fluids. The current device allows the levitation of a superconducting sphere and has several provisions made for allowing precise control over its motion. We report on progress in the detection and control systems of the prototype and demonstrate how uniform circular motion can be implemented.
The quest of null electromagnetics knots from Seifert fibration
(Elsevier, 2022) Arrayás, Manuel; Tiemblo, Alfredo; Trueba, José L.
In this work we find new null electromagnetic fields that are exact solutions of Maxwell equations in vacuum and generalize the hopfion. The hopfion is an exact solution of Maxwell equations in vacuum in which all the field lines (both electric and magnetic) are topologically equivalent to closed and linked circles, forming a mathematical structure called Hopf fibration. Here we present a generalization to include other field lines topology, such as the Seifert fibration in which the field lines form linked torus knots. Included in this generalization are fields that ergodically fill torus surfaces.