Search results for "Matematica"

A genetic algorithm to calibrate dynamical systems: Confidence intervals for parameters and residuals

2018

This paper presents a genetic algorithm to calibrate dynamical systems that is able to calculate confidence intervals for the parameters of the system. As an application case is used to calibrate the system that reproduces the dynamical response of the General Factor of Personality (GFP) to a given stimulus, particularly to a stimulant drug dose. The model is called in Literature as the response model and includes an integro-differential equation. The presented application case is a single case ABC experimental design where the stimulus is methylphenidate.

Assessing supply chain risks in the automotive industry through a modified MCDM-based FMECA

2020

Supply chains are complex networks that receive assiduous attention in the literature. Like any complex network, a supply chain is subject to a wide variety of risks that can result in significant economic losses and negative impacts in terms of image and prestige for companies. In circumstances of aggressive competition among companies, effective management of supply chain risks (SCRs) is crucial, and is currently a very active field of research. Failure Mode, Effects and Criticality Analysis (FMECA) has been recently extended to SCR identification and prioritization, aiming at reducing potential losses caused by lack of risk control. This article has a twofold objective. First, SCR assess…

Explaining the rising precariat in Spain

2020

[EN] Spanish GDP indicator figures recover while the risk of poverty has not stopped increasing since 2007 given the continuous austerity policies adopted by Governments, while labour and welfare conditions have worsened. A new phenomenon is emerging: the flattening of the Spanish middle class. This study proposes a model to quantify the number of individuals according to their level of precariousness in Spain. The model allows us to predict the behaviour of society in Spain given the mimetic nature of humans by constructing a discrete finite epidemiological model that classifies and quantifies the population in Spain according to its risk of precariousness. Our results show a rise in the p…

Spectral study of {R, s + 1, k}- and {R, s + 1, k, *}-potent matrices

2020

[EN] The {R, s +1, k}- and {R, s +1, k, *}-potent matrices have been studied in several recent papers. We continue these investigations from a spectral point of view. Specifically, a spectral study of {R, s + 1, k} -potent matrices is developed using characterizations involving an associated matrix pencil (A, R). The corresponding spectral study for {R, s+ 1, k, *}-potent matrices involves the pencil (A*, R). In order to present some properties, the relevance of the projector I - AA(#). where A(#) is the group inverse of A is highlighted. In addition, some applications and numerical examples are given, particularly involving Pauli matrices and the quaternions.

Multi-criteria decision methods to support the maintenance management of complex systems

2019

[ES] Esta tesis doctoral propone el uso de métodos de toma de decisiones multi-criterio (MCDM, por sus iniciales en inglés) como herramienta estratégica para apoyar la gestión del mantenimiento de sistemas complejos. El desarrollo de esta tesis doctoral se enmarca dentro de un acuerdo de cotutela entre la Università degli Studi di Palermo (UNIPA) y la Universitat Politècnica de València (UPV), dentro de sus respectivos programas de doctorado en 'Ingeniería de Innovación Tecnológica' y 'Matemáticas'. Estos programas están estrechamente vinculados a través del tópico MCDM, ya que proporciona herramientas cruciales para gestionar el mantenimiento de sistemas complejos reales utilizando análisi…

On the stability of the localized single-valued extension property under commuting perturbations

2013

This article concerns the permanence of the single-valued extension property at a point under suitable perturbations. While this property is, in general, not preserved under sums and products of commuting operators, we obtain positive results in the case of commuting perturbations that are quasi-nilpotent, algebraic, or Riesz operators.

In vitro validation of biomedical polyester-based scaffolds: Poly(lactide-co-glycolide) as model-case

2018

[EN] Monitoring and understanding the in vitro behaviour of polyester based scaffolds both comprising the study of the hydrolytic degradation and the cell seeding viability is essential to ensure the desired functionality, according to a given biomedical purpose. As a model case to compare the performance of techniques to monitor the in vitro behaviour, poly(lactide-co-glycolide) (PLGA) scaffolds were chosen. The in vitro hydrolytic degradation of PLGA scaffolds was carried out in water and phosphate buffered saline (PBS). The evolution of the mass loss, the molar mass, the thermal properties and the surface morphology were monitored. The hydrolytic degradation media was correspondingly eva…

Management of uncertain pairwise comparisons in AHP through probabilistic concepts

2019

Abstract Fast and judicious decision-making is paramount for the success of many activities and processes. However, various degrees of difficulty may affect the achievement of effective and optimal solutions. Decisions should ideally meet the best trade-off among as many of the involved factors as possible, especially in the case of complex problems. Substantial cognitive and technical skills are indispensable, while not always sufficient, to carry out optimal evaluations. One of the most common causes of wrong decisions derives from uncertainty and vagueness in making forecasts or attributing judgments. The literature shows numerous efforts towards the optimization and modeling of uncertai…

Integrazione e apprendimento: un’esperienza laboratoriale tra Lingua e Matematica alla Scuola dell’Infanzia

2017

Non-equilibrium thermodynamics, heat transport and thermal waves in laminar and turbulent superfluid helium

2018

This review paper puts together some results concerning non equilibrium thermodynamics and heat transport properties of superfluid He II. A one-fluid extended model of superfluid helium, which considers heat flux as an additional independent variable, is presented, its microscopic bases are analyzed, and compared with the well known two-fluid model. In laminar situations, the fundamental fields are density, velocity, absolute temperature, and heat flux. Such a theory is able to describe the thermomechanical phenomena, the propagation of two sounds in liquid helium, and of fourth sound in superleak. It also leads in a natural way to a two-fluid model on purely macroscopical grounds and allow…