Monte Carlo Simulation of a Modified Chi Distribution with Unequal Variances in the Generating Gaussians. A Discrete Methodology to Study Collective Response Times

The Chi distribution is a continuous probability distribution of a random variable obtained from the positive square root of the sum of k squared variables, each coming from a standard Normal distribution (mean = 0 and variance = 1). The variable k indicates the degrees of freedom. The usual expression for the Chi distribution can be generalised to include a parameter which is the variance (which can take any value) of the generating Gaussians. For instance, for k = 3, we have the case of the Maxwell-Boltzmann (MB) distribution of the particle velocities in the Ideal Gas model of Physics. In this work, we analyse the case of unequal variances in the generating Gaussians whose distribution we will still represent approximately in terms of a Chi distribution. We perform a Monte Carlo simulation to generate a random variable which is obtained from the positive square root of the sum of k squared variables, but this time coming from non-standard Normal distributions, where the variances can take any positive value. Then, we determine the boundaries of what to expect when we start from a set of unequal variances in the generating Gaussians. In the second part of the article, we present a discrete model to calculate the parameter of the Chi distribution in an approximate way for this case (unequal variances). We also comment on the application of this simple discrete model to calculate the parameter of the MB distribution (Chi of k = 3) when it is used to represent the reaction times to visual stimuli of a collective of individuals in the framework of a Physics inspired model we have published in a previous work

Razones que impulsan a los empresarios a expansionarse a través de franquicia

El objetivo general de este trabajo consiste en estudiar y analizar las razones que impulsan a los empresarios a expansionarse mediante el formato de franquicia. En segundo lugar, determinar si para explicar la confianza o uso de la franquicia dentro del sistema de franquicia español se pueden identificar clases latentes. Es decir, grupos de franquiciadores cuyas variables explicativas tienen relaciones distintas con el porcentaje de unidades franquiciadas. La metodología empleada es la regresión de clases latentes (RCL) que ha sido poco utilizada en la investigación de franquicia

Design and production of an experimental UHPFRC bending-active footbridge

[EN] This paper describes the design, production and testing of an experimental footbridge made of ultra-highperformance fibre-reinforced concrete (UHPFRC). The prototype has a span length of 5.4 m and is made of a very slender pre-stressed UHPFRC deck (6 cm deep, 1.2 m wide), a 0.55 m high central deviator of the same material, and an external lower tensioning stainless-steel cable system. The service configuration of the structure involves a significant permanent bending of the deck, because of its slenderness; this initial bending is introduced in a controlled manner during the production process and prior to the installation, and results in an efficient, lightweight, and elegant structure with a high stiffness-to-self-weight ratio. The structural concept belongs to the category named active bending, which has been recent subject of research. Specifically, the structure is a bowstring system in which the bending-active member is made of UHPFRC, which constitutes the main novelty of this research. The suitability of UHPFRC as a material for bending active applications has been investigated, and a method to determine the limiting pre-stress of UHPFRC bending-active cross sections has been developed. The activation process and relevant limit states have been checked by means of a 3D frame finite-element model. The paper concludes with the description of the production process and the installation of the footbridge in the final location, as well as the successful results of the load tests and the geometric control of the novel footbridge prototype.The authors are grateful to Rover Maritime for facilitating the placement of the footbridge as access to their prototype in the H2020 Reshealience project.Lazaro, C.; Castro-Bugallo, MC.; Navarro-Gregori, J.; Priego De Los Santos, E.; Serna Ros, P. (2023). Design and production of an experimental UHPFRC bending-active footbridge. Engineering Structures. 294. https://doi.org/10.1016/j.engstruct.2023.11674229

Percentile Study of chi Distribution. Application to Response Time Data.

As a continuation of our previous work, where a Maxwell-Boltzmann distribution was found to model a collective's reaction times, in this work we will carry out a percentile study of the χ distribution for some freedom ranging from k = 2 to k = 10. The most commonly used percentiles in the biomedical and behavioral sciences have been included in the analysis. We seek to provide a look-up table with percentile ratios, taken symmetrically about the median, such that this distribution can be identified in practice in an easy way. We have proven that these ratios do not depend upon the variance chosen for the k generating Gaussians. In general, the χ probability density, generalized to take any value of the variance, represents an ideal gas in a k-dimensional space. We also derive an approximate expression for the median of the generalized χ distribution. In the second part of the results, we will focus on the practical case of k = 3, which represents the ideal gas in physics, and models quite well the reaction times of a human collective. Accurately, we will perform a more detailed scrutiny of the percentiles for the reaction time distribution of a sample of 50 school-aged children (7200 reaction times)

Propuesta de optimización del modelo de abastecimiento para tiendas Easy en Bogotá. Caso empresarial.

Los objetivos de este proyecto están enfocados, en el mejoramiento del proceso de aprovisionamiento de las tiendas EASY de Bogotá, mediante un modelo de Cross docking desde un centro de distribución, donde se asegure la disponibilidad de los productos y el nivel de servicio de la Organización buscando reducir los costos y generando valor agregado al proceso.Especialista en Gerencia LogísticaEspecializació

Cultura Tributaria

Este artí­culo se propuso como objetivo basándose en una revisión bibliográfica caracterizar las posibles tendencias investigativas relacionadas con la cultura tributaria. Para poder cumplimentar el objetivo previsto se realizó una revisión de la literatura reportada en Google Académico y se obtuvieron un total de 217 referencias. Se revisó igualmente empleando la Base de Datos de Scopus para la búsqueda del término “tax culture” en el titulo de los artí­culos, obteniéndose de esta forma 29 referencias.Como tendencias analizadas en los estudios reportados se pudieron determinar para el   caso de las publicaciones en idioma español, investigaciones relacionadas con:a) Programas o estrategias educativas para desarrollar una cultura tributaria.b) Mediciones del nivel de la cultura tributaria para grupos poblaciones especí­ficos.La revisión de la literatura en idioma inglés reflejo como tendencias investigativas importantes:a) Contribuciones de carácter teórico   que a revisaron la concepción de cultura tributaria.b) Comparaciones entre paí­ses.Estas tendencias permiten concluir la necesidad de realizar estudios comparativos entre paí­ses de América Latina y de investigaciones de tipo cuantitativo que permitan un análisis detallado de los factores que inciden en la cultura tributari

Machinery Failure Approach and Spectral Analysis to Study the Reaction Time Dynamics over Consecutive Visual Stimuli: An Entropy-Based Model.

The reaction times of individuals over consecutive visual stimuli have been studied using an entropy-based model and a failure machinery approach. The used tools include the fast Fourier transform and a spectral entropy analysis. The results indicate that the reaction times produced by the independently responding individuals to visual stimuli appear to be correlated. The spectral analysis and the entropy of the spectrum yield that there are features of similarity in the response times of each participant and among them. Furthermore, the analysis of the mistakes made by the participants during the reaction time experiments concluded that they follow a behavior which is consistent with the MTBF (Mean Time Between Failures) model, widely used in industry for the predictive diagnosis of electrical machines and equipment

From the simplest equations of Hydrodynamics to science and engineeringmodeling skills

[EN] The development of modeling skills is a very important issue in Science teaching nowadays. The present workillustrates how, from the simplest equations of hydrodynamics, it is possible to contribute to this end. Bernoulliand continuity equations are included in Physics syllabi of secondary and university levels, and can be seen as alinking between general and professional education. By means of the proposed project, students are taken throughgeneral stages which are usually present in any engineering project or research work based on modeling and simu-lation. such as the formulation of the problem, the statement of the Physics model, a computational simulationand the comparison between theory and experiments. This kind of project allows for the development of modelingskills and also to some other typical skills of the scientist's and engineer's pro les nowadays, such as tting andgraphing analysis. It is common to see that secondary and rst year university courses do not contribute muchto the formation of modeling skills, instead they rather contribute to particular skills from the perspective of thedi erent subjects. On the other hand, students are usually more motivated for the modeling of real world situationsthan for idealized ones.[ES] El desarrollo de habilidades relacionadas con la modelación es un aspecto esencial en la enseñanza de las ciencias hoy en día. El presente trabajo ilustra una propuesta de cómo desarrollar habilidades de modelación físico-matemáticas desde las ecuaciones más simples de la hidrodinámica, es decir, la ecuación de Bernoulli y la ecuación de continuidad. Estas ecuaciones representan la conservación de la energía y de la masa, respectivamente, y están presentes comúnmente en los programas de Física para la Enseñanza Secundaria y Universidad. A través del proyecto propuesto, el estudiante transita a través de etapas generales usualmente presentes en los proyectos de innovación ingenieril o de investigación, es decir, el surgimiento de la idea inicial, el planteamiento del modelo físico, la exploración computacional del mismo, y la comparación con medidas experimentales. El proyecto presentado hace uso directo de habilidades tales como la realización de ajustes y análisis gráficos, típicas en los perfiles de ingenieros e investigadores en la actualidad. Por otro lado, los estudiantes presentan más motivación por aquellas situaciones más cercanas a la realidad que por las muy idealizadas.This work has been partially supported by funds of the Interdisciplinar Modeling Group InterTech from the Universitat Politècnica de València, Spain.Castro-Palacio, JC.; Velázquez-Abad, L.; Perea, MH.; Navarro-Pardo, E.; Acosta-Iglesias, D.; Fernández-De-Córdoba-Castellá, P. (2017). Desarrollo de habilidades de modelación desde las ecuaciones más simples de la Hidrodinámica. Modelling in Science Education and Learning. 10(2):211-222. doi:10.4995/msel.2017.7143SWORD211222102Mendonça, P. C. C., & Justi, R. (2013). The Relationships Between Modelling and Argumentation from the Perspective of the Model of Modelling Diagram. International Journal of Science Education, 35(14), 2407-2434. doi:10.1080/09500693.2013.811615Chapman S.J. (2003). Fortran 90/95 for Scientists and Engineers, 2nd Ed. McGraw-Hill Series in General Engineering.Fishbane P.M., Gasiorowicz, S. & Thornton S. (1996). Physics for scientists and engineers. Prentice Hall.Justi, R. S., & Gilbert, J. K. (2002). Science teachers’ knowledge about and attitudes towards the use of models and modelling in learning science. International Journal of Science Education, 24(12), 1273-1292. doi:10.1080/09500690210163198Nair, C. S., Patil, A., & Mertova, P. (2009). Re-engineering graduate skills – a case study. European Journal of Engineering Education, 34(2), 131-139. doi:10.1080/03043790902829281Patil A.S. (2005). The global engineering criteria for the development of a global engineering profession. World Transaction on Engineering Education 4(1), 49-52.Radcliffe D.F. (2005). Innovation as a meta attribute for graduate engineers. International Journal of Engineering Education 21(2), 194-199.Resnick R., Halliday D., & Krane K. (1999). Physics. 4th Ed. Mexico: CECSA.Wedelin, D., Adawi, T., Jahan, T., & Andersson, S. (2015). Investigating and developing engineering students’ mathematical modelling and problem-solving skills. European Journal of Engineering Education, 40(5), 557-572. doi:10.1080/03043797.2014.987648Wellington P., Thomas I., Powell I., & Clarke B. (2002). Authentic assessment applied to engineering and business undergraduate consulting teams. International Journal of Engineering Education 18(2), 168-179

Medición de la responsabilidad social corporativa. Propuesta de medición para el ámbito del sistema de franquicia

El presente trabajo de investigación trata de conocer el estado de la responsabilidad social corporativa, su concepto y dimensiones. La revisión de la literatura nos indica que se trata de un constructo complejo multidimensional, difícil de medir. Ello conlleva la falta de consenso entre los investigadores en la forma de medir la responsabilidad social corporativa. A partir de esta multidimensionalidad se propone una forma de medición en el ámbito del sector de la franquicia en España. Para ello se ha medido la responsabilidad social corporativa de una importante muestra de cadenas franquiciadoras que operan en España, incluyendo componentes que intentan recoger las responsabilidades ética, legal, filantrópica, medioambiental, frente a clientes y a empleados. No es frecuente encontrar una medida de la responsabilidad social corporativa, en el ámbito de la franquicia, que recoja todas las componentes anteriores, lo que supone una aportación relevante de esta investigación.This research paper seeks to know the state of corporate social responsibility, which are their concepts and dimensions. The literature review indicates that this is a complex multidimensional construct, difficult to measure. This implies a lack of consensus among researchers on how to measure corporate social responsibility. From this multidimensional topic we propose a form of measurement in the field of the Spanish franchising sector. Corporate Social Responsibility has been measured in an important sample of franchise chains operating in Spain, including components that try to gather the ethical, legal, philanthropic, environmental, to customers and employees, responsibilities. It is rare to find a measure of corporate social responsibility in the field of franchising containing all the above mentioned components, representing a significant contribution of this research