Ramón Herrera
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View article: Connecting Early Dark Energy to Late Dark Energy by the Diluting Matter Potential
Connecting Early Dark Energy to Late Dark Energy by the Diluting Matter Potential Open
In this work we study a scale invariant gravity theory containing two scalar fields, dust particles and a measure defined from degrees of freedom independent of the metric. The integration of the degrees of freedom that define the measure …
View article: On Modelling and State Estimation of DC Motors
On Modelling and State Estimation of DC Motors Open
Direct current motors are widely used in a plethora of applications, ranging from industrial to modern electric (and intelligent) vehicle applications. Most recent operation methods of these motors involve drives that are designed based on…
View article: Unifying Inflation, dark energy and dark matter with a scalar field and exotic fermions
Unifying Inflation, dark energy and dark matter with a scalar field and exotic fermions Open
In this paper we consider a new approach to unify inflation and the late universe with dark energy and dark matter formulated in a model that includes a non-Riemannian metric independent measure and a scalar field with spontaneously broken…
View article: Reconstructing inflation and reheating in the framework of a generalized $\mathcal{F}(H)$ Friedmann equation
Reconstructing inflation and reheating in the framework of a generalized $\mathcal{F}(H)$ Friedmann equation Open
The reconstruction of an inflationary universe considering the parametrization of the scalar spectral index as a function of the number of $e-$folds in the framework of a modified Friedmann equation is analyzed. In this context, we examine…
View article: Unification: inflation and dark epochs from multi-field theory.
Unification: inflation and dark epochs from multi-field theory. Open
A two scalar field model that incorporates non Riemannian Measures of integration or usually called Two Measures Theory (TMT) is introduced, in order to unify the early and present universe. In the Einstein frame, a K-essence is generated …
View article: A Complex-Valued Stationary Kalman Filter for Positive and Negative Sequence Estimation in DER Systems
A Complex-Valued Stationary Kalman Filter for Positive and Negative Sequence Estimation in DER Systems Open
In medium- and low-voltage three-phase distribution networks, the load imbalance among the phases may compromise the network voltage symmetry. Inverter-interfaced distributed energy resources (DERs) can contribute to compensating for such …
View article: Inflation in a scalar-vector gravity theory
Inflation in a scalar-vector gravity theory Open
We study the possibility that inflation is driven by a scalar field together with a vector field minimally coupled to gravity. By assuming an effective potential that incorporates both fields into the action, we explore two distinct scenar…
View article: Constant-roll inflation with a complex scalar field
Constant-roll inflation with a complex scalar field Open
We consider inflation with a constant rate of rolling in which a complex scalar field plays the role of inflaton during the inflationary epoch. We implement the inflationary analysis for an accredited angular speed $\dotθ$ which satisfies …
View article: On Accurate Discrete-Time Dynamic Models of an Induction Machine
On Accurate Discrete-Time Dynamic Models of an Induction Machine Open
Induction machines have become the standard for highly demanding industrial applications. This has led to the utilization of modern discrete-time control techniques (such as model predictive control) that require the estimation of internal…
View article: Speed of sound and scalar spectral index: Reconstructing inflation and reheating in a non-canonical theory
Speed of sound and scalar spectral index: Reconstructing inflation and reheating in a non-canonical theory Open
In this article we analyze the reconstruction of inflation in the framework of a non-canonical theory. In this sense, we study the viability of reconstructing the background variables assuming a non-lineal kinetic term given by $K(X,ϕ)=X+g…
View article: Warm inflation with bulk viscous pressure for different solutions of an anisotropic universe
Warm inflation with bulk viscous pressure for different solutions of an anisotropic universe Open
We study a warm inflationary model for different expansions assuming an anisotropic universe described by Bianchi I metric. The universe is filled with a scalar field or inflaton, radiation, and bulk viscous pressure. We carry out the infl…
View article: Reconstructing k-inflation from $n_s(N)$ and reheating constraints
Reconstructing k-inflation from $n_s(N)$ and reheating constraints Open
Inspired by the reconstruction scheme of the inflaton field potential $V(ϕ)$ from the attractors$n_s(N)$, we investigate the viability of reconstruct the inflationary potential within the framework of k-inflation for a non-linear kinetic t…
View article: Hybrid Vehicle CO2 Emissions Reduction Strategy Based on Model Predictive Control
Hybrid Vehicle CO2 Emissions Reduction Strategy Based on Model Predictive Control Open
This work proposes a hybrid drive controlled configuration, using a minimum emissions search algorithm, which ensures the operation of the Internal Combustion Engine (ICE) in its fuel efficiency range, minimizing CO2 emissions by controlli…
View article: Unification: Emergent universe followed by inflation and dark epochs from multi-field theory
Unification: Emergent universe followed by inflation and dark epochs from multi-field theory Open
A two scalar field model that incorporates non Riemannian Measures of integration or usually called Two Measures Theory (TMT) is introduced, in order to unify the early and present universe. In the Einstein frame a K-essence is generated a…
View article: Reconstructing inflation and reheating in $f(ϕ)T$ gravity
Reconstructing inflation and reheating in $f(ϕ)T$ gravity Open
The reconstruction of an inflationary universe in the context of one $f(ϕ)T$ gravity, in which $T$ corresponds to the trace of energy momentum tensor is studied. To realize this reconstruction during the inflationary epoch, we consider as …
View article: Unifying inflation with early and late dark energy with multiple fields: Spontaneously broken scale invariant two measures theory
Unifying inflation with early and late dark energy with multiple fields: Spontaneously broken scale invariant two measures theory Open
A unified multi scalar field model with three flat regions is discussed. The\nthree flat regions are the inflation, early and late dark energy epochs. The\npotential is obtained by a spontaneous breaking of scale invariance generated\nby N…
View article: G-constant-roll inflation
G-constant-roll inflation Open
The constant-roll inflation in the context of Galilean inflation or G-inflation is analyzed. By considering a coupling function $G(φ,χ)\propto g(φ)\,χ^n$ for the model of G-inflation, we find different expressions for a suitable developmen…
View article: Model Predictive Control Scheme of a Four-Level Quasi-Nested Converter Fed AC-Drive, with dc-Link Voltage-Drift Compensation
Model Predictive Control Scheme of a Four-Level Quasi-Nested Converter Fed AC-Drive, with dc-Link Voltage-Drift Compensation Open
In this paper, a Model Predictive Control (MPC) strategy is introduced for its application in a four-level quasi-nested topology, feeding an Interior Permanent Magnet Synchronous Machine (IPMSM) AC-drive. The proposed control strategy is c…
View article: Warm inflation with bulk viscous pressure for different solutions of an anisotropic universe
Warm inflation with bulk viscous pressure for different solutions of an anisotropic universe Open
We study a warm inflationary model for different expansions assuming an anisotropic universe described by Bianchi I metric. The universe is filled with a scalar field or inflaton, radiation, and bulk viscous pressure. We carry out the infl…
View article: Instant preheating in a scale invariant two measures theory
Instant preheating in a scale invariant two measures theory Open
The instant preheating mechanism in the framework of a scale invariant two measures theory is studied. We introduce this mechanism into a non oscillating inflationary model as another possible solution to the reheating of the universe in t…
View article: Warm <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>G</mml:mi></mml:math> inflation: Intermediate model
Warm inflation: Intermediate model Open
A warm-intermediate inflationary universe model is studied in the presence of\nthe Galileon coupling $G(\\phi,X)=g(\\phi)X$. General conditions required for\nsuccessful inflation are deduced and discussed from the background and\ncosmologi…
View article: Reconstructing braneworld inflation
Reconstructing braneworld inflation Open
The reconstruction of a braneworld inflationary universe considering the parametrization (or attractor) of the scalar spectral index $n_s(N)$ in terms of the number of $e$-foldings N is developed. We also study the possibility that the rec…
View article: Large-scale (in) stability analysis of an exactly solved coupled dark-energy model
Large-scale (in) stability analysis of an exactly solved coupled dark-energy model Open
Assuming a non-gravitational interaction amongst the dark fluids of our\nuniverse namely, the dark matter and dark energy, we study a specific\ninteraction model in the background of a spatially flat\nFriedmann-Lema\\^itre-Robertson-Walker…
View article: Stable Emergent Universe from Conservation Laws
Stable Emergent Universe from Conservation Laws Open
In this paper, based on JCAP 1608 (2016) 049, we show that there is a class of emergent universes models, derived from scale invariant two measures theories with spontaneous symmetry breaking (s.s.b) of the scale invariance, which can have…