Linear complementary pairs of skew constacyclic codes

Linear complementary pairs (LCPs) of codes have been studied since they were introduced in the context of discussing mitigation measures against possible hardware attacks to integrated circuits. Since the security parameters for LCPs of codes are defined from the (Hamming) distance and the dual distance of the codes in the pair, and the additional algebraic structure of skew constacyclic codes provides tools for studying the the dual and the distance of a code, we study the properties of LCPs of skew constacyclic codes. As a result, we give a characterization for those pairs, as well as multiple results that lead to constructing pairs with designed security parameters. We extend skew BCH codes to a constacyclic context and show that an LCP of codes can be immediately constructed from a skew BCH constacyclic code. Additionally, we describe a Hamming weight-preserving automorphism group in the set of skew constacyclic codes, which can be used for constructing LCPs of codes.Comment: 25 pages, 0 figure

Structural aspects of Hamilton-Jacobi theory

In our previous papers [11,13] we showed that the Hamilton-Jacobi problem can be regarded as a way to describe a given dynamics on a phase space manifold in terms of a family of dynamics on a lower-dimensional manifold. We also showed how constants of the motion help to solve the Hamilton-Jacobi equation. Here we want to delve into this interpretation by considering the most general case: a dynamical system on a manifold that is described in terms of a family of dynamics (`slicing vector fields') on lower-dimensional manifolds. We identify the relevant geometric structures that lead from this decomposition of the dynamics to the classical Hamilton-Jacobi theory, by considering special cases like fibred manifolds and Hamiltonian dynamics, in the symplectic framework and the Poisson one. We also show how a set of functions on a tangent bundle can determine a second-order dynamics for which they are constants of the motion.Comment: 26 pages. Minor changes (some minor mistakes are corrected

An Application of Cooperative Game Theory to Distributed Control

18th World CongressThe International Federation of Automatic ControlMilano (Italy) August 28 - September 2, 2011In this paper we propose to study the underlying properties of a given distributed control scheme in which a set of agents switch between different communication strategies that define which network links are used in order to regulate to the origin a set of unconstrained linear systems. The problems of how to decide the time-varying communication strategy, share the benefits/costs and detect which are the most critical links in the network are solved using tools from game theory. The proposed scheme is demonstrated through a simulation example

Conformal and non-conformal symmetries in 2D dilaton gravity

We introduce new extra symmetry transformations for generic 2D dilaton-gravity models. These symmetries are non-conformal but special linear combinations of them turn out to be the extra (conformal) symmetries of the CGHS model and the model with an exponential potential. We show that one of the non-conformal extra symmetries can be converted into a conformal one by means of adequate field redefinitions involving the metric and the derivatives of the dilaton. Finally, by expressing the Polyakov-Liouville effective action in terms of an auxiliary invariant metric, we construct one-loop models which maintain the extra symmetry of the classical action. © 1997 Elsevier Science B.V.M. N. is grateful to the Spanish MEC, CSIC and also the IMAFF for a research contract.Peer Reviewe

Sticky grains do not change the universality class of isotropic sandpiles

We revisit the sandpile model with ``sticky'' grains introduced by Mohanty and Dhar [Phys. Rev. Lett. {\bf 89}, 104303 (2002)] whose scaling properties were claimed to be in the universality class of directed percolation for both isotropic and directed models. Simulations in the so-called fixed-energy ensemble show that this conclusion is not valid for isotropic sandpiles and that this model shares the same critical properties of other stochastic sandpiles, such as the Manna model. %as expected from the existence of an extra %conservation-law, absent in directed percolation. These results are strengthened by the analysis of the Langevin equations proposed by the same authors to account for this problem which we show to converge, upon coarse-graining, to the well-established set of Langevin equations for the Manna class. Therefore, the presence of a conservation law keeps isotropic sandpiles, with or without stickiness, away from the directed percolation class.Comment: 4 pages. 3 Figures. Subm. to PR

Structural aspects of Hamilton–Jacobi theory

The final publication is available at Springer via http://dx.doi.org/10.1142/S0219887816500171In our previous papers [11, 13] we showed that the Hamilton–Jacobi problem can be regarded as a way to describe a given dynamics on a phase space manifold in terms of a family of dynamics on a lower-dimensional manifold. We also showed how constants of the motion help to solve the Hamilton–Jacobi equation. Here we want to delve into this interpretation by considering the most general case: a dynamical system on a manifold that is described in terms of a family of dynamics (‘slicing vector fields’) on lower-dimensional manifolds. We identify the relevant geometric structures that lead from this decomposition of the dynamics to the classical Hamilton– Jacobi theory, by considering special cases like fibred manifolds and Hamiltonian dynamics, in the symplectic framework and the Poisson one. We also show how a set of functions on a tangent bundle can determine a second-order dynamics for which they are constants of the motion.Peer ReviewedPostprint (author's final draft

An alternative procedure to measure railroad track irregularities. Application to a scaled track

In this paper an alternative procedure to accurately measure static railroad track irregularities is proposed and applied to a scaled railroad track. The purpose of this work is the determination of highlyprecise measured data in short track segments that needs to be used as input in the validation of railroad computational models that are used for on-board railroad track measurement systems. The procedure consists of the use of a topographic total station combined with a postprocessing of the measured data that reduces misalignment errors and provide the analytical ideal geometry of the track together with its irregular geometry characterized in terms of the magnitudes of track gauge, vertical profile, alignment and cross level. Experimental results are compared to standard magnitudes of full scale tracks showing that real track geometry can differ from PSD-based predicted one. This supports the application of the proposed procedure for an accurate geometric determination of short track segments.Spanish Ministry of Science, Innovation and Universities under the project reference TRA2017-86355-C2-1-

Artificial neural networks applied to the measurement of lateral wheel-rail contact force: A comparison with a harmonic cancellation method

This paper presents a method for the experimental measurement of the lateral wheel-rail contact force based on Artificial Neural Networks (ANN). It is intended to demonstrate how an Artificial Intelligence (AI) method proves to be a valid alternative to other approaches based on sophisticated mathematical models when it is applied to the wheel-rail contact force measurement problem. This manuscript addresses the problem from a computational and experimental approach. The artificial intelligence algorithm has been experimentally tested in a real scenario using a 1:10 instrumented scaled railway vehicle equipped with a dynamometric wheelset running on a 5-inch-wide track. The obtained results show that the ANN approach is an easy and computationally efficient method to measure the applied lateral force on the instrumented wheel that requires the use of fewer sensors.Conserjería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía. Project reference US-1257665. Project: 2020/00000096

Cortes compensados para la deformación principal alpina en el borde sur oriental del Sistema Central español (Zona de Tamajón, Guadalajara)

Las estructuras alpinas principales del borde sur oriental del Sistema Central Español (zona de Tamajón) resultan ser dos cabalgamientos de dirección N70oE, con dirección de transporte hacia el SE, con retrocabalgamientos y fallas de transferencia asociadas. La dirección de transporte de los cabalgamientos es coherente con la dirección de acortamiento horizontal de la "etapa Guadarrama" (N1500E), a la cual están asociados genéticamente. El efecto de los cabalgamientos en la cobertera mesozoica es el desarrollo de diferentes tipos de pliegues asimétricos. El acortamiento, deducido de la restauración de cortes geológicos, es de 17-19

Theoretical and experimental nucleation and growth of precipitates in a medium carbon–vanadium steel

Using the general theory of nucleation, the nucleation period, critical radius, and growth of particles were determined for a medium carbon V-steel. Several parameters were calculated, which have allowed the plotting of nucleation critical time vs. temperature and precipitate critical radius vs. temperature. Meanwhile, an experimental study was performed and it was found that the growth of precipitates during precipitation obeys a quadratic growth equation and not a cubic coalescence equation. The experimentally determined growth rate coincides with the theoretically predicted growth ratePeer ReviewedPostprint (author's final draft