FIC/FEM formulation with matrix stabilizing terms for incompressible flows at low and high Reynolds numbers

The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-006-0060-yWe present a general formulation for incompressible fluid flow analysis using the finite element method. The necessary stabilization for dealing with convective effects and the incompressibility condition are introduced via the Finite Calculus method using a matrix form of the stabilization parameters. This allows to model a wide range of fluid flow problems for low and high Reynolds numbers flows without introducing a turbulence model. Examples of application to the analysis of incompressible flows with moderate and large Reynolds numbers are presented.Peer ReviewedPostprint (author's final draft

Possibilities of finite calculus in computational mechanics

The expression ‘finite calculus’ refers to the derivation of the governing differential equations in mechanics by invoking balance of fluxes, forces, etc. in a space–time domain of finite size. The governing equations resulting from this approach are different from those of infinitesimal calculus theory and they incorporate new terms which depend on the dimensions of the balance domain. The new governing equations allow the derivation of naturally stabilized numerical schemes using any discretization procedure. The paper discusses the possibilities of the finite calculus method for the finite element solution of convection–diffusion problems with sharp gradients, incompressible fluid flow and incompressible solid mechanics problems and strain localization situations.&nbsp

Consistent pressure Laplacian stabilization for incompressible continua via higher‐order finite calculus

We present a stabilized numerical formulation for incompressible continua based on a higher‐order Finite Calculus (FIC) approach and the finite element method. The focus of the paper is on the derivation of a stabilized form for the mass balance (incompressibility) equation. The simpler form of the momentum equations neglecting the non‐linear convective terms, which is typical for incompressible solids, Stokes flows and Lagrangian flows is used for the sake of clarity. The discretized stabilized mass balance equation adds to the standard divergence of velocity term a pressure Laplacian and an additional boundary term. The boundary term is relevant for the accuracy of the numerical solution, especially for free surface flow problems. The Laplacian and boundary stabilization terms are multiplied by non‐linear parameters that have an extremely simple expression in terms of element sizes, the pressure and the discrete residuals of the incompressibility equation and the momentum equations, thus ensuring the consistency of the method. The stabilized formulation allows solving the incompressible problem iteratively using an equal‐order interpolation for the velocities (or displacements) and the pressure, which are the only unknowns. The use of additional pressure gradient projection variables, typical of many stabilized methods, is unnecessary. The formulation is particularly useful for heterogeneous incompressible materials with discontinuous material properties, as it allows computing all the stabilization matrices at the element level. Details of the finite element formulation are given. The good behaviour of the new pressure Laplacian stabilization (PLS) technique is shown in simple but demonstrative examples of application. A very accurate solution was obtained in all cases in 2–3 iterations. Copyright © 2010 John Wiley & Sons, Ltd

IndElec: A Software for Analyzing Party Systems and Electoral Systems

IndElec is a software addressed to compute a wide range of indices from electoral data, which are intended to analyze both party systems and electoral systems in political studies. Further, IndElec can calculate such indices from electoral data at several levels of aggregation, even when the acronyms of some political parties change across districts. As the amount of information provided by IndElec may be considerable, this software also aids the user in the analysis of electoral data through three capabilities. First, IndElec automatically elaborates preliminary descriptive statistical reports of computed indices. Second, IndElec saves the computed information into text files in data matrix format, which can be directly loaded by any statistical software to facilitate more sophisticated statistical studies. Third, IndElec provides results in several file formats (text, CSV, HTML, R) to facilitate their visualization and management by using a wide range of application softwares (word processors, spreadsheets, web browsers, etc.). Finally, a graphical user interface is provided for IndElec to manage calculation processes, but no visualization facility is available in this environment. In fact, both the inputs and outputs for IndElec are arranged in files with the aforementioned formats.

Nodally exact Ritz discretizations of 1D diffusion–absorption and Helmholtz equations by variational FIC and modified equation methods

The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-005-0011-zThis article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions.Peer ReviewedPostprint (author's final draft

The Teacher: another Variable in the Use of Foreign Language Learning Strategies?

The Bologna process aims to create the European Higher Education Framework (EHEF) by making academic degree and quality assurance standards more comparable and compatible throughout Europe. The EHEF has different implications for university students, representing a change in emphasis from ‘teaching’ to ‘learning’, from a teacher-centred approach to a student-centred approach. In the last thirty years, researchers have discussed the role of teachers and students in the language learning-teaching process. Until then, the acquisition of a foreign language was focused on the teacher’s methodology. In the 80s and 90s, a series of student-centred approaches emerged, with the aim of making students more autonomous and independent in their learning. Language learning strategies are part of the tools used to improve language learning. There are different definitions and taxonomies of language learning strategies (Chamot (2001), Cohen (1998), Oxford (1990), O'Malley (1990) and Wenden & Rubin (1987) and there have been extensive descriptive studies on the different variables affecting the use of learning strategies including gender, previous linguistic knowledge, motivation, learning styles and/or second language versus foreign language acquisition. This paper aims to explore the instructor’s conscious or unconscious influence students’ use of learning strategies. To undertake this study, a group of teachers was asked to assess the 50 strategies presented in an adapted version of the Strategies Inventory Language Learning (Oxford 1990) according to their suitability and practicality for their students. The participants were lecturers from the French and English Department at Cádiz University. The languages included in the study were English, French and German for specific and general purposes

Modelación numérica de deslizamientos de ladera en embalses mediante el método de partículas y elementos finitos (PFEM)

Se presentan resultados obtenidos mediante la aplicación del MétododePartículasyElementosFinitos (PFEM) en la simulación dedeslizamientosdeladeraenembalses. Es un fenómeno complejo, por la interacción entre el material deslizado, la masa de agua del embalse, yel conjunto formado por el vaso y la presa. PFEM es un esquema numérico original con el que se ha afrontado con éxito la resolución de problemas de interacción fluido-estructura. Combina un enfoque Lagrangiano con la resolución de las ecuaciones deelementosfinitosmediante la generación de una malla, que se actualiza en cada paso de tiempo. Se presentan resultados de casos de validación en los que se han reproducido ensayos en laboratorio existentes en la bibliografía técnica. Se muestran también otros cálculos más complejos, sobre la cartografía a escala real de un embalse, donde se aprecia el fenómeno de generación de la ola, su propagación por el embalse y la afección a la presa. Por último, se ha modelado el deslizamiento ocurrido en 1958 en la bahía de Lituya (Alaska), enel que la caída de 90 millones de toneladas de roca produjo una ola que alcanzó una sobreelevación máxima de 524 m en la ladera opuesta. Los resultados permiten afirmar que PFEM puede ser una herramienta útil enel análisis de riesgos frente a este tipo de fenómenos, ofreciendo una buena aproximación de las afecciones potenciale

Innovación en Ecuador: un enfoque espacial/Innovation in Ecuador: a spatial approach

Este trabajo explora la distribución espacial del éxito innovador de las empresas en Ecuador entre 2012 y 2014. Los datos cuentan con una muestra de 6275 empresas con representatividad provincial. En base a esta información, los objetivos que persigue esta investigación están orientados a i) establecer si existe o no relaciones espaciales en las provincias del Ecuador y ii) resaltar políticas estatales que contribuyan a la innovación. Los resultados muestran que existe influencia espacial en el éxito innovador. Asimismo, el modelo planteado sugiere políticas orientadas a la innovación mediante apoyo del Gobierno así como financiamiento por parte de la banca privada. This paper explores the spatial distribution of the innovative success of companies in Ecuador between 2012 and 2014. The data has a sample of 6275 companies with provincial representation. Based on this information, the objectives pursued by this research are aimed at i) establishing whether or not there are spatial relationships in the provinces of Ecuador and ii) highlighting state policies that contribute to innovation. The results show that there is a spatial influence on innovative success. Likewise, the proposed model suggests policies oriented towards innovation through government support as well as financing from private banks. Palabras clave: Spillovers espaciales, Modelo espacial autorregresivo, Modelo de error espacial, Modelo espacial de Durbin. Keywords: Spatial spillovers, Spatial autoregressive model, Spatial Error Model, Spatial Durbin Model

Discrete/finite element modelling of rock cutting with a TBM disc cutter

The final publication is available at Springer via http://dx.doi.org/10.1007/s00603-016-1133-7This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro- and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool–rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.Peer ReviewedPostprint (published version

Probióticos Como Aditivos Dietéticos Para Cerdos. Una Revisión/Probiotics as Dietetic Additives for Pigs. A Review

Por varias décadas se ha utilizado en los sistemas intensivos y semi intensivos de producción porcina los antibióticos promotores de crecimiento, con la finalidad de controlar los problemas digestivos y respiratorios y mejorar la eficiencia. Sin embargo, su utilización en la alimentación de animales destinados al consumo humano, se relaciona con la crisis de salud global por la resistencia a los antimicrobianos. A nivel internacional, varias jurisdicciones respondieron a través de la restricción o prohibición del uso de estos productos. Esta situación condujo a que diferentes grupos de investigación se centraran en el estudio y desarrollo de alternativas para mantener la salud de los animales y el rendimiento productivo. Dentro de estas alternativas se incluyen probióticos que son uno de los aditivos alimentarios más estudiados y se definen como microorganismo(s) vivo (s) que cuando se adicionan en cantidades adecuadas influyen benéficamente en la salud del huésped. La aplicación de estos productos en la alimentación de cerdos puede modular la respuesta inmune y mejorar los parámetros zootécnicos de conversión alimenticia y ganancia de peso vivo final. Además, se pueden utilizar en el tratamiento de enfermedades infecciosas digestivas, como la diarrea, lo que aporta un beneficio económico importante en la industria porcina. En este estudio, se realizó una revisión de las diferentes etapas fisiológicas de cerdos con 23 citas bibliográficas y 50 referencias sobre la utilización de probióticos en la especie porcina como la utilización de probióticos en la alimentación. For several decades, antibiotic growth promoters have been used in intensive and semi-intensive systems of swine production, with the purpose of controlling digestive and respiratory problems and improving efficiency. However, its use in feeding animals destined for human consumption is related to the global health crisis due to resistance to antimicrobials. Internationally, several jurisdictions responded by restricting or prohibiting the use of these products. This situation led to different research groups focusing on the study and development of alternatives to maintain animal health and productive performance. These alternatives include probiotics that are one of the most studied food additives and are defined as live microorganism (s) that, when added in adequate amounts, beneficially influence the health of the host. The application of these products in pig feed can modulate the immune response and improve the zootechnical parameters of feed conversion and final live weight gain. In addition, they can be used in the treatment of digestive infectious diseases, such as diarrhea, which provides a significant economic benefit in the swine industry. In this study, a review was made of the different physiological stages of pigs with 23 citations and 50 references on the use of probiotics in swine as the use of probiotics in food. Palabras Claves: Probióticos, antibióticos, rendimiento productivo, salud del huésped. Keywords: Probiotics, antibiotics, productive performance, guest health