Numerical resolution of an exact heat conduction model with a delay term

In this paper we analyze, from the numerical point of view, a dynamic thermoelastic problem. Here, the so-called exact heat conduction model with a delay term is used to obtain the heat evolution. Thus, the thermomechanical problem is written as a coupled system of partial differential equations, and its variational formulation leads to a system written in terms of the velocity and the temperature fields. An existence and uniqueness result is recalled. Then, fully discrete approximations are introduced by using the classical finite element method to approximate the spatial variable and the implicit Euler scheme to discretize the time derivatives. A priori error estimates are proved, from which the linear convergence of the algorithm could be derived under suitable additional regularity conditions. Finally, a two-dimensional numerical example is solved to show the accuracy of the approximation and the decay of the discrete energy.Peer ReviewedPostprint (published version

Servicios de salud pública en San Salvador: diseño de instrumento de medición

El presente estudio tenía como objetivo hacer una evaluación de la calidad de atención en los servicios de salud en la ciudad de San Salvador. Para ello, se diseñó un instrumento a partir del modelo teórico sugerido por Donabedian (1966) que contiene las dimensiones de estructura, proceso-resultado y accesibilidad. Es un estudio descriptivo mediante encuesta (León y Montero, 2007), un diseño retrospectivo; la muestra es no probabilística de tipo incidental, constituida por 1,210 personas entre hombres (42.1%) y mujeres (57.9%) con edad media de 32.5 años. Entre los resultados se tienen que el cuestionario (ECASS) posee adecuadas propiedades psicométricas de fiabilidad y validez. Así mismo, se encontró que existen diferencias significativas en la calidad de atención en salud entre los centros de atención privada y los públicos, indicando que es de mejor calidad la atención en los centros privados. Algunos indicadores considerados como negativos son: mala atención en el sistema de salud público salvadoreño (63.4%), los tiempos de espera entre una cita y otra, son muy largos (70.8%), en el sistema de salud público el acceso al médico especialista es sumamente difícil (68.4%). Estos resultados pueden ayudar al sistema de salud ha implementar mejoras en el proceso de atención en salud pública.La presente investigación fue subvencionada por la Universidad Tecnológica de El Salvador. Agradezco sinceramente a los estudiantes de psicología de la asignatura Seminario de Investigación por su valioso apoyo y participación en la recolección y tabulación de los datos. Las solicitudes de información, separatas y otros documentos relativos al presente estudio pueden hacerlos a la dirección postal: calle Arce, 1020, Universidad Tecnológica de El Salvador, Vicerrectoría de Investigación y Proyección Social, Dirección de Investigaciones, edificio José Martí, 2ª planta, o al correo electrónico [email protected] Tecnológica de El Salvado

Uniqueness for a high order ill posed problem

In this work, we study a high order derivative in time problem. First, we show that there exists a sequence of elements of the spectrum which tends to infinity and therefore, it is ill posed. Then, we prove the uniqueness of solutions for this problem by adapting the logarithmic arguments to this situation. Finally, the results are applied to the backward in time problem for the generalized linear Burgers’ fluid, a couple of heat conduction problems and a viscoelastic model.Agencia Estatal de Investigación | Ref. PGC2018-096696-B-I00Agencia Estatal de Investigación | Ref. PID2019-105118GB-I0

On the instability for an incremental problem in elastodynamics

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this short note, we consider some issues regarding the instability of some elastodynamical problems when the elasticity tensor is not positive definite. By using the so-called logarithmic convexity argument, we prove the instability of solutions when the time derivative of the elasticity tensor is semi-definite negative or it satisfies another restriction on the coefficients. The uniqueness of the solution is also concluded. Finally, a simple one-dimensional example is provided to demonstrate the numerical behaviour of the instability.Ministerio de Ciencia, Innovación y Universidades | Ref. PID2019-105118GB-I0

Fast spatial behavior in higher order in time equations and systems

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this work, we consider the spatial decay for high-order parabolic (and combined with a hyperbolic) equation in a semi-infinite cylinder. We prove a Phragmén-Lindelöf alternative function and, by means of some appropriate inequalities, we show that the decay is of the type of the square of the distance to the bounded end face of the cylinder. The thermoelastic case is also considered when the heat conduction is modeled using a high-order parabolic equation. Though the arguments are similar to others usually applied, we obtain new relevant results by selecting appropriate functions never considered before.Agencia Estatal de Investigación | Ref. PGC2018-096696-B-I00Agencia Estatal de Investigación | Ref. PID2019-105118GB-I0

Propuesta de libro de texto: fundamentos de bases de datos, saber y hacer

Through the years, we have detected a problem in the academic program of Information and Communication Technologies of our University, a recurrent problem in the teaching learning process, accentuated with the associated paradigm to the construction of knowledge by the own pupil. We are specifically referring to the search and assimilation of content inside the book texts about Digital Databases. The work exposed in this paper represents an effort for contributing in the reduction of educational slump in areas related to good design and construction of data banks. The textbook of this research, treats all the thematical content in this area, which are studied in the whole academic program. These and another relevant subjects in the database area are retaken from a simple but fundamentally practical theorical focus, allowing the studying on acquiring a significative learning in an easier and single source way. As a result, we present the almost definitive version of the book which is been tested on pilot group

Interfaz gráfica de usuario para la detección de microcalcificaciones mediante análisis de mamografía digitalizada

The graphical user interface (GUI) are all graphic elements that help to communicate with a system. The design of a GUI allow to land the central idea of a draft information technology. Today technology has become one of the largest and most useful tools to automate and facilitate processes for that reason fit into any kind of productive sectors, for example, in the health sector. The CAD systems (Systems Computer Aided Diagnosis) are the type of technology used in the health sector, in order to automate online modular learning environment with a fast placed in service. In the present paper the use of a Learning Management Systems (LMS) as continuous education tool is proposed

Magnetic field induced inversion in the effect of particle size on powder cohesiveness

Experimental measurements are reported on the tensile yield stress of magnetofluidized beds of fine magnetic powders operated in the cross-flow configuration. In the absence of externally applied magnetic field the yield stress of the powder depends on particle size as expected, i.e., it increases as bead size is decreased. This trend is however inverted when an external magnetic field is applied. It is suggested that the average orientation of interparticle contacts relative to the direction of the field as affected by particle size plays a relevant role on the magnetic yield stress of these systems.Ministerio de Ciencia y Tecnología de España-FIS2006-0364

A semi-automated method for daily age estimation in larval populations by discriminant function models

Discriminant analysis including the best age-correlated variables selected by SMLR’s to construct a predictive model based on somatic and otolith biometry was applied. Age of anchovy larvae ranging from 10 to 12 mm collected along Western Mediterranean coasts during MEDIAS209 survey were estimated by otolith microstructure analysis and compared with the number of daily increments estimated by the model. The model compound by Perimeter2 + Area2 was able to estimate correctly the age of the otoliths in 75% of the cases assuming ±1 day of error increasing to 90% assuming ±2 days of error with mean values of APE (3.33%) and CV (4.71%) systematically low. The results indicate the precision of the increment estimates. Moreover, no differences between the estimated ages from direct readings and those estimated by the model were observed. The proposed method implies a reduction in the subjectivity factor and the cost/benefit ratio for ageing studies in fish larvae.Postprint1,586