An equation of state for purely kinetic k-essence inspired by cosmic topological defects

We investigate the physical properties of a purely kinetic k-essence model with an equation of state motivated in superconducting membranes. We compute the equation of state parameter $w$ and discuss its physical evolution via a nonlinear equation of state. Using the adiabatic speed of sound and energy density, we restrict the range of parameters of the model in order to have an acceptable physical behavior. Furthermore, we analyze the evolution of the luminosity distance $d_{L}$ with redshift $z$ by comparing (normalizing) it with the $\Lambda$CDM model. Since the equation of state parameter is $z$-dependent the evolution of the luminosity distance is also analyzed using the Alcock-Paczy\'{n}ski test.Comment: 19 pages, 13 figures, typos corrected and references adde

Input variable selection for forecasting models

2002 IFAC15th Triennial World Congress, Barcelona, SpainThe selection of input variables plays a crucial role when modelling time series. For nonlinear models there are not well developed techniques such as AIC and other criteria that work with linear models. In the case of Short Term Load Forecasting (STLF) generalization is greatly influenced by such selection. In this paper two approaches are compared using real data from a Spanish utility company. The models used are neural networks although the algorithms can be used with other nonlinear models. The experiments show that that input variable selection affects the performance of forecasting models and thus should be treated as a generalization problem

A new concept of invariance for saturated systems

In this paper, a new concept of invariance for saturated linear systems is presented. This new notion of invariance, denoted SNS-invariance, has a number of geometrical properties that makes its use suitable for the estimation of the domain of attraction of saturated systems. The notion of SNS-domain of attraction, that serves as an estimation of the domain of attraction of a saturated system, is introduced. It is shown that, in case of single input saturated systems, any contractive set is contained in the SNS-domain of attraction. A simple algorithm that converges to the SNS-domain of attraction is presented. Some illustrative examples are given

Management of professional competences

A continuación se encontrará la aplicación de un proceso pedagógico orientado al desarrollo de un trabajo de grado, como requerimiento dentro de las políticas del Centro de Investigaciones de la Facultad de Estudios a Distancia – FAEDIS, y la selección de un proyecto de investigación para la Especialización en Alta Gerencia, como factores determinantes del éxito en el proceso de graduación. En consecuencia se tomaron como ejes de ejecución de la metodología académica los siguientes parámetros: investigación por el método de estudio de caso, incorporando conceptos científicos, implementando el componente teórico-práctico y el sentido ético integrador entre la visión y la acción, además de analizar posibilidades y desarrollar habilidades para la asertividad en la toma estratégica de decisiones. El Plan de Estudios fortalece la investigación concretamente en la Gestión Humana; es por ello que en este documento se hará referencia a la gestión del talento humano empresarial (o estatal), teniendo en la cuenta las competencias laborales individuales de sus empleados en procura del bienestar integral y general de éstos, y por ende del cumplimiento de los objetivos empresariales.Following is the implementation of an educational process aimed at developing a thesis, as a requirement within the policies of the Facultad de Estudios a Distancia - FAEDIS, and the selection of a research project for Specialization in Senior Management, as determinants of success in the process of graduation. Consequently the following parameters were taken as fundamental in the execution of the academic methodology: case study investigation method, incorporating scientific concepts, implementing the theoretical and practical component and integrating ethical sense between vision and action, in addition to analyzing possibilities and developing skills for the assertiveness in strategic decision making. The curriculum strengthens research specifically in Human Resources, which is why management of the enterprise (or state) human talent will be referred to in the present document, taking into account the individual work skills of their employees in pursuit of full and comprehensive welfare of these, and therefore the fulfillment of business objectives