Gestión óptima de aguas subterráneas : regulación frente a no regulación

En este artículo se comparan dos modelos de gestión de aguas subterráneas: control y no-control. La diferencia entre ambos viene dada porque en el primero de ellos se computa el coste de uso del recurso, mientras que en el segundo no. La demanda de agua subterránea se desagrega por cultivos lo que permite obtener una asignación inter e intratemporal del recurso. Asimismo se realiza la aplicación sobre el acuífero de Ascoy-Sopalmo (Cuenca del Segura). La obtención del valor presente del excedente neto de los agricultores en ambos escenarios permite concluir que la pérdida de eficiencia es mínima para unos valores normales de las tasas de descuento y recarga.In this paper two management models of groundwater (control and no-control) are compared. The difference between these models is that in the first one user cost is considered whilst in the second one is not. The groundwater demand is disaggregated by crops, which makes possible to obtain an inter and intratemporal resource allocation. Furthermore, an application to the aquifer of Ascoy-Sopalmo (Segura Basin) is carried out. From the present value of the farmer's net surplus, derived in both models, we can conclude that the efficiency loss is minimum for normal values of the discount rate and recharge rate

Mathematical modeling with digital technological tools for interpretation of contextual situations

This article has the goal of proposing physical contextual situations modeling as a way to interpret mathematical representations that are produced by digital technological tools. Thus, there is an experimental situation-problem about a physical phenomenon that is modeled through video analysis and dynamic geometry software; the methodological model Cuvima conducts the experimental activity. Pre-testing and post-testing measuring instruments were designed to obtain the information and previous conceptions of ten graduate students in Mathematical Education, which showed a conceptual change. Similarly, results prove that digital technology, from a didactical sequence, supports and strengthens experimental work simplifying modeling processes of a physical phenomenon, promoting the use of mathematical representations to solve a situation-problem

The Effect of Post-Weaning Management on the Physico-Chemical and Textural Quality of Beef From Bulls and Steers

There is an increasing interest for extensification in Europe due to environmental and animal welfare concerns. Furthermore, forage-fed beef may present benefits for human health. However, animals fed at pasture produce in some cases darker and tougher meat. It has been shown that castration or a grain-finishing period before slaughter could improve some sensory traits of beef from pasture. The objective of this work was to study the impact of castration and four feeding systems (grazing, grazing + 70 days concentrate, grazing + 100 days concentrate, 200 days concentrate) on the quality of beef from yearling bulls and steers

Generación de piloto automático difuso para maniobras de embarcaciones

This paper introduces a method to generate autopilots for ship headings by using issues from the observation of control actions performed by human operators. The controller is designed based on fuzzy logic and uses triangular membership functions for the antecedent and consequent functions for Singleton type. For an automatic adjustment of the consequential, the recursive least squares method was used. This method is used to generate and validate the course driver of a 350-m tanker, at different load conditions.Este documento presenta un método para generar pilotos automáticos para rumbo de embarcación mediante el uso de asuntos provenientes de la observación de acciones de control realizadas por operadores humanos. El controlador está diseñado basado en lógica difusa (fuzzy logic) y utiliza funciones de pertenencia triangular para las funciones antecedentes y consecuentes para tipo Singleton. Para un ajuste automático de la consecuente, se utilizó el método de mínimos cuadrados recursivos. Este método es utilizado para generar y validar el conductor de curso de un buque cisterna de 350 m, en diferentes condiciones de carga

A metapopulation approach to identify targets for Wolbachia-based dengue control

Over the last decade, the release of Wolbachia-infected Aedes aegypti into the natural habitat of this mosquito species has become the most sustainable and long-lasting technique to prevent and control vector-borne diseases, such as dengue, zika, or chikungunya. However, the limited resources to generate such mosquitoes and their effective distribution in large areas dominated by the Aedes aegypti vector represent a challenge for policymakers. Here, we introduce a mathematical framework for the spread of dengue in which competition between wild and Wolbachia-infected mosquitoes, the cross-contagion patterns between humans and vectors, the heterogeneous distribution of the human population in different areas, and the mobility flows between them are combined. Our framework allows us to identify the most effective areas for the release of Wolbachia-infected mosquitoes to achieve a large decrease in the global dengue prevalence. © 2022 Author(s)

Universal insulating-to-metallic crossover in tight-binding random geometric graphs

Within the scattering matrix approach to electronic transport, the scattering and transport properties of tight-binding random graphs are analyzed. In particular, we compute the scattering matrix elements, the transmission, the channel-to-channel transmission distributions (including the total transmission distribution), the shot noise power, and the elastic enhancement factor. Two graph models are considered: random geometric graphs and bipartite random geometric graphs. The results show an insulating to a metallic crossover in the scattering and transport properties by increasing the average degree of the graphs from small to large values. Also, the scattering and transport properties are shown to be invariant under a scaling parameter depending on the average degree and the graph size. Furthermore, for large connectivity and in the perfect coupling regime, the scattering and transport properties of both graph models are well described by the random matrix theory predictions of electronic transport, except for bipartite graphs in particular scattering setups.Comment: 13 pages, 16 figure