Personnel selection: an analysis of 3 companies

Treball Final de Grau en Administració d'Empreses. Codi: AE1049. Curs 2020/202

On quasiperiodic perturbations of elliptic equilibrium points

This work focusses on quasiperiodic time-dependent perturbations of ordinary differential equations near elliptic equilibrium points. This means studying $$\dot{x}=(A+\varepsilon Q(t,\varepsilon))x+\varepsilon g(t,\varepsilon)+ h(x,t,\varepsilon),$$ where $A$ is elliptic and $h$ is ${\cal O}(x^2)$. It is shown that, under suitable hypothesis of analyticity, nonresonance and nondegeneracy with respect to $\varepsilon$, there exists a Cantorian set ${\cal E}$ such that for all $\varepsilon\in{\cal E}$ there exists a quasiperiodic solution such that it goes to zero when $\varepsilon$ does. This quasiperiodic solution has the same set of basic frequencies as the perturbation. Moreover, the relative measure of the set $[0,\,\varepsilon_0]\setminus{\cal E}$ in $[0,\,\varepsilon_0]$ is exponentially small in $\varepsilon_0$. The case $g\equiv 0$, $h\equiv 0$ (quasiperiodic Floquet theorem) is also considered. Finally, the Hamiltonian case is studied. In this situation, most of the invariant tori that are near the equilibrium point are not destroyed, but only slightly deformed and ``shaken" in a quasiperiodic way. This quasiperiodic ``shaking" has the same basic frequencies as the perturbation

Resonance tongues and spectral gaps in quasi-periodic schrödinger operators with one or more frequencies. A numerical exploration

Abstract. In this paper we investigate numerically the spectrum of some representative examples of discrete one-dimensional Schr¨odinger operators with quasi-periodic potential in terms of a perturbative constant b and the spectral parameter a. Our examples include the well-known Almost Mathieu model, other trigonometric potentials with a single quasi-periodic frequency and generalisations with two and three frequencies. We computed numerically the rotation number and the Lyapunov exponent to detect open and collapsed gaps, resonance tongues and the measure of the spectrum. We found that the case with one frequency was significantly different from the case of several frequencies because the latter has all gaps collapsed for a sufficiently large value of the perturbative constant and thus the spectrum is a single spectral band with positive Lyapunov exponent. In contrast, in the cases with one frequency considered, gaps are always dense in the spectrum, although some gaps may collapse either for a single value of the perturbative constant or for a range of values. In all cases we found that there is a curve in the (a, b)-plane which separates the regions where the Lyapunov exponent is zero in the spectrum and where it is positive. Along this curve, which is b = 2 in the Almost Mathieu case, the measure of the spectrum is zero.Preprin

Making Transport Safer: V2V-Based Automated Emergency Braking System

An important goal in the field of intelligent transportation systems (ITS) is to provide driving aids aimed at preventing accidents and reducing the number of traffic victims. The commonest traffic accidents in urban areas are due to sudden braking that demands a very fast response on the part of drivers. Attempts to solve this problem have motivated many ITS advances including the detection of the intention of surrounding cars using lasers, radars or cameras. However, this might not be enough to increase safety when there is a danger of collision. Vehicle to vehicle communications are needed to ensure that the other intentions of cars are also available. The article describes the development of a controller to perform an emergency stop via an electro-hydraulic braking system employed on dry asphalt. An original V2V communication scheme based on WiFi cards has been used for broadcasting positioning information to other vehicles. The reliability of the scheme has been theoretically analyzed to estimate its performance when the number of vehicles involved is much higher. This controller has been incorporated into the AUTOPIA program control for automatic cars. The system has been implemented in Citroën C3 Pluriel, and various tests were performed to evaluate its operation

Magnetic Trails: A Novel Artificial Pheromone for Swarm Robotics in Outdoor Environments

[EN] Swarm robotics finds inspiration in nature to model behaviors, such as the use of pheromone principles. Pheromones provide an indirect and decentralized communication scheme that have shown positive experimental results. Real implementations of pheromones have suffered from slow sensors and have been limited to controlled environments. This paper presents a novel technology to implement real pheromones for swarm robotics in outdoor environments by using magnetized ferrofluids. A ferrofluid solution, with its deposition and magnetization system, is detailed. The proposed substance does not possess harmful materials for the environment and can be safely handled by humans. Validation demonstrates that the substance represents successfully pheromone characteristics of locality, diffusion and evaporation on several surfaces in outdoor conditions. Additionally, the experiments show an improvement over the chemical representation of pheromones by using magnetic substances and existing magnetometer sensor technologies, which provide better response rates and recovery periods than MOX chemical sensors. The present work represents a step toward swarm robotics experimentation in uncontrolled outdoor environments. In addition, the presented pheromone technology may be use by the broad area of swarm robotics for robot exploration and navigation.We would like to warmly thank Cindy Calderon-Arce. This paper was achieved thanks to her support and advice. Special thanks also to Research and Outreach Vice-Rectory at Costa Rica Institute of Technology (VIE, ITCR), for their support of PROE project (code VIE 1440036).Brenes-Torres, JC.; Blanes Noguera, F.; Simó Ten, JE. (2022). Magnetic Trails: A Novel Artificial Pheromone for Swarm Robotics in Outdoor Environments. Computation. 10(6):1-16. https://doi.org/10.3390/computation1006009811610

Resonance tongues in the quasi-periodic hill-Schrödinger equation with three frequencies

In this paper we investigate numerically the following Hill’s equation x00 + (a + bq(t))x = 0 where q(t) = cos t + cosp2t + cosp3t is a quasiperiodic forcing with three rationally independent frequencies. It appears,also, as the eigenvalue equation of a Schr¨odinger operator with quasi-periodic potential. Massive numerical computations were performed for the rotation number and the Lyapunov exponent in order to detect open and collapsed gaps, resonance tongues. Our results show that the quasi-periodic case with three independent frequencies is very different not only from the periodic analogs, but also from the case of two frequencies. Indeed, for large values of b the spectrum contains open intervals at the bottom. From a dynamical point of view we numerically give evidence of the existence of open intervals of a, for large b where the system is nonuniformly hyperbolic: the system does not have an exponential dichotomy but the Lyapunov exponent is positive. In contrast with the region with zero Lyapunov exponents, both the rotation number and the Lyapunov exponent do not seem to have square root behavior at endpoints of gaps. The rate of convergence to the rotation number and the Lyapunov exponent in the nonuniformly hyperbolic case is also seen to be different from the reducible case.Preprin

Cambio Global. Impacto de la Actividad Humana sobre el Sistema Tierra

Esta obra, dirigida al público en general y elaborada por un equipo interdisciplinar, aborda con un lenguaje claro y asequible pero sin renunciar al rigor científico, el complejo problema del cambio global, un desafío de dimensiones colosales para la humanidad. El cambio global se define en esta obra como el conjunto de cambios en los procesos fundamentales que definen el funcionamiento de la biosfera derivados de la actividad humana. Los autores describen las múltiples dimensiones del cambio global, sus causas y sus consecuencias. Se describe la transformación de la superficie del planeta Tierra por la actividad humana y sus impactos sobre los ciclos del agua, los elementos y el sistema climático, incluyendo la introducción de miles de compuestos químicos sintéticos en la biosfera. Esta exposición pretende despejar la confusión que el aluvión de noticias e informaciones, a veces contradictorias, genera en la sociedad. Los autores prestan particular atención a la definición de las estrategias de adaptación y mitigación que los distintos actores de la sociedad, desde ciudadanos a políticos, pueden desplegar para minimizar el impacto del cambio global, animándoles al mismo tiempo a aprovechar las oportunidades que estos cambios pueden conllevar

El ensamble de arañas en un hotspot dendroflorístico del este de Uruguay

In previous studies, Uruguay has been considereda biogeographical crossroads. Paso Centurión and Sierra de Ríos in eastern Uruguay were recently enteredi nto the National System of Protected Areas. Thelandscape is characterized by a mosaic of differentecosystems located in one of the dendrofloristic hotspots proposed for the country. The spiders constitute a megadiverse group useful for the monitoring of natural environments. The aim of this study was toknow the composition and structure of the spider faunaof this protected area. The sampling of spiders was carried out in two different environments (ravine andriparian forests) and three methods were used: groundvacuum, foliage beating and manual collection. Agreater richness of spider families, species and guilds was recorded compared to previous studies in other protected areas from Uruguay. The two environments showed differences in taxonomic composition and species replacement. Araneidae, Theridiidae and Salticidae represented the families with the high estspecies richness. The family Symphytognathidae and55 species are new records for the country. The finding of more southern records for several species confirm that the area is located in a border zone with other biogeographic units at regional level. This fact supports the crossroads condition for the country, provides key information for the management of the area and increases the number of priority spider species for conservation in UruguayEstudios recientes han considerado a Uruguay como una encrucijada biogeográfica. Paso Centurión y Sierra de Ríos en el este de Uruguay fue recientemente ingresado al Sistema Nacional de Áreas Protegidas. El paisaje está caracterizado por un mosaico de diferentes ecosistemas situado en uno de los hotspots dendroflorísticos propuestos para el país. Las arañas constituyen un grupo megadiverso que es útil para el control de los entornos naturales. El objetivo del estudio consistió en conocer la composición y estructura de la araneofauna de esta área protegida. El estudio se llevó a cabo en dos tipos de ambientes (bosque ribereño y bosque de quebrada) y se utilizaron tres métodos: aspirador de suelo, batido de follaje y recolección manual. Se registró una mayor riqueza de familias, especies y gremios de arañas en comparación con estudios previos en otras áreas protegidas de Uruguay. Los dos ambientes mostraron diferencias en la composición taxonómica y reemplazo de especies. Araneidae, Theridiidae y Salticidae fueron las familias con mayor riqueza específica. La familia Symphytognathidae y 55 especies son nuevos registros para el país. El hallazgo de registros más australes para varias especies confirma que esta área se encuentra en una zona límite con otras unidades biogeográficas a nivel regional. Esto refuerza el carácter de enclave biogeográfico para el país, aporta información relevante para el manejo del área y aumenta el número de especies prioritarias de arañas para la conservación en Uruguay

Investigación en marketing turístico: un análisis de las publicaciones en el período 1995-2003

El presente trabajo analiza la investigación en marketing turístico en publicaciones españolas y principales revistas internacionales en turismo durante el período 1995-2003. La revisión se centra en el análisis de cuatro cuestiones principales: (i) evolución de los trabajos de marketing turístico, (ii) descripción de su autoría (autores, universidades), (iii) temas estudiados (utilizando el esquema de clasificación del Journal of Marketing), y aplicación en subsectores, (iv) metodología empleada y análisis de datos. A través del análisis de contenido, se han revisado 272 publicaciones. Tourism Management presenta el mayor porcentaje de publicaciones en marketing turístico. Del análisis efectuado se destaca el papel central del comportamiento del consumidor durante el período analizado y en todas las revistas. En general, más de la mitad de estos trabajos se aplican a destinos turísticos y tipos de turismo. La mayor parte de la investigación presenta una orientación empírica, predominando los análisis de datos descriptivos.This study reviews tourism marketing research published in Spanish marketing publications and selected Spanish and international tourism journals for the period 1995-2003. The review includes the analysis of four main issues: (i) evolution of tourism marketing papers, (ii) affiliation of published tourism marketing papers (i.e., researchers, universities), (iii) research topics in tourism marketing (using the classification scheme that had been used by Journal of Marketing), and industry applications, and (iv) methods of study design and data analysis. Using content analysis, we reviewed 272 tourism marketing-focused papers. Tourism Management offers the higher number of tourism marketing papers. Findings evidence the substantial literature on tourist behaviour during the period under analysis across the international journals. Overall, more than a half of the studies took place with tourist destinations and specific types of tourism. In general, tourism marketing research was predominantly empirical in its approach. Researchers most frequently used descriptive data analysis

Valores de los jóvenes y responsabilidad social corporativa en las decisiones de compra: un estudio empírico en España y Portugal

La Responsabilidad Social Corporativa (RSC) está adquiriendo un notable interés en la investigación y práctica del marketing. Parece apuntarse una mayor conciencia sobre la necesidad de lograr resultados en una triple dimensión: económica, medioambiental y social. Sin embargo, existen escasas investigaciones sobre la RSC que permitan corroborar esta afirmación desde la perspectiva del consumidor. El presente trabajo, en el ámbito hispano-luso, pretende contribuir en la comprensión de las percepciones del consumidor sobre la RSC y su influencia en el comportamiento de compra. Concretamente, se plantean cuatro objetivos: evaluar el grado de conocimiento de los jóvenes españoles y portugueses sobre la RSC, analizar la importancia de la RSC en las decisiones de compra, conocer los valores de los jóvenes que potencialmente contribuyen a la adopción de criterios de RSC en sus decisiones de compra, y analizar las percepciones de jóvenes universitarios sobre las actividades afines a la RSC.Corporate Social Responsibility (CSR) is becoming the subject of considerable interest in both marketing research and practice. Popular wisdom in the area tells us consumers are increasingly more concerned with corporate activities, not just in an economic sense, but in terms of their environmental and social impact as well. There are very few studies, however, able to corroborate this statement. With this study we attempt to fill this gap by focusing on the consumer perceptions of CSR and their influence on purchasing behaviour. The paper thus aims to: analyse the level of knowledge of CSR by Spanish and Portuguese young consumers on the perception of socially responsible companies, measure the importance of CSR dimensions on consumer purchasing decisions, assess the effect of consumers’ values on the utilization of CSR dimensions on consumer purchasing decisions, and analyse consumer perceptions of the activities of companies deemed socially responsible