Non-steady Phenomena in the Vibration of Viscous Cylindrical Long Liquid Bridges

This paper deals with the dynamic response of long cylindrical viscous liquid bridges subjected to an oscillatory microgravity field whose frequency varies linearly with time. The problem has been solved by using a one-dimensional model for the dynamics, derived from Cosserat theory for continuum, in which the axial velocity is considered to be constant over each cross-section of the liquid column. The dynamic response of the liquid bridge has been obtained by applying the Laplace transform to the problem formulation. The results obtained show that a variable -frequency excitation could give rise to erroneous measurements of the resonance frequencies of viscous liquid bridges

A Theoretical Approach to Impulsive Motion of Viscous Liquid Bridges

This paper deals with the dynamics of isothermal, axisymmetric, viscous liquid columns held by capillary forces between two circular, concentric, solid disks. The transient response of the bridge to an excitation consisting of a small change in the value of the acceleration acting along its axis has been solved by using a linearised one-dimensional Cosserat model, which includes viscosity effects. The main hypothesis of this model is that the axial velocity is considered constant in each section of the liquid bridge. The analysis has been performed by using the Laplace transform

Response of a liquid bridge to an acceleration varying sinusoidally with time

The response of a long cylindrical liquid column subjected to an axial microgravity field has been experimentally studied on a TEXUS sounding rocket flight to check with theoretical predictions. The expected response of the liquid bridge was a quasi-static amphora-type deformation of the cylindrical shape. However, the experimental results showed a more complex behaviour. Nevertheless it has been possible to find out the reasons of this discrepancy except for a mysterious 0.5% uncertainty in the stimuli

Indices of the iterates of R3R^3-homeomorphisms at Lyapunov stable fixed points

Given any positive sequence (\{c_n\}_{n \in {\Bbb N}}), we construct orientation preserving homeomorphisms (f:{\Bbb R}^3 \to {\Bbb R}^3) such that (Fix(f)=Per(f)=\{0\}), (0) is Lyapunov stable and (\limsup \frac{|i(f^m, 0)|}{c_m}= \infty). We will use our results to discuss and to point out some strong differences with respect to the computation and behavior of the sequences of the indices of planar homeomorphisms.Comment: 19 pages, 8 figure

Metodología didáctica y tecnología educativa en el desarrollo de las competencias cognitivas: aplicación en contextos universitarios

El presente estudio plantea como objetivo el análisis de distintas estrategias y técnicas metodológicas vinculadas al uso de la Tecnología Educativa desde un planteamiento coherente con un desarrollo de las competencias cognitivas. El método se plantea a partir de un análisis descriptivo y un análisis factorial con un cuestionario mixto de 2 dimensiones como instrumento. Los 121 alumnos de 2 universidades españolas valoran muy positivamente la aplicación del aprendizaje colaborativo y la integración de la Tecnología Educativa con todas sus posibilidades a pesar que optan mayoritariamente por la modalidad presencial en detrimento de la modalidad a distancia. En este sentido, se concluye que se dan valoraciones muy positivas respecto a las distintas estrategias y técnicas metodológicas que potencian enfoques activos y colaborativos vinculados al desarrollo de las competencias cognitivas y basadas en el concepto de aprender haciendo

OPTIMAL REGULATION AND GROWTH IN A NATURAL-RESOURCE-BASED ECONOMY

This paper develops a two-sector model for a renewable natural resource based economy. Pareto efficient results show the optimal harvesting rate that allows for sustained long-run optimal growth, which is upper-bounded by the biological rate of reproduction. Regulation prevents from resource over-exploitation and exhaustion which arise under open access. The Ramsey policy allowing the competitive economy to reach the first-best solution, leads the government to tax harvesting activity from firms and distribute the receipts among households. In the short-run the tax is variable. In the long-run, the lower the intrinsic rate of reproduction the higher the constant unit tax on the resource use.Natural Resources, Efficiency, Open Access, Ramsey Regulation, Growth.

Teaching methodology and educational technology in the development of cognitive competences: implementation in university contexts

This research analyses different methodological strategies and techniques involving the use of Educational Technology from a consistent educational approach with a development of cognitivecompetences. The method arises from a descriptive analysis and a factor analysis with a questionnaire with 2 dimensions as an instrument. The sample of 121 students from 2 Spanish universities value positively the application of collaborative learning and integration of Educational Technology with all its possibilities even though they mostly prefer classroomteaching than e-learning. In this sense, we conclude that there are very positive appreciations about the different methodological strategies and techniques that enhance active and collaborative approach involving the development of cognitive competences and based on the concept of learning by doing

Ortotipografía científica en publicaciones médico-quirúrgicas: la normativa académica relativa a la prefijación

El objetivo del presente artículo es analizar el grado de cumplimiento de la normativa académica relativa a la correcta escritura de las palabras prefijadas (recogida en la nueva Ortografía de 2010) que realizan algunas publicaciones periódicas de carácter científico-técnico y, en concreto, del ámbito médico-quirúrgico. Se trata de una labor de profundización en un estudio anterior (Aguilar Ruiz 2012: 9-12). Para ello, comentamos los errores e incorrecciones más recurrentes de un corpus de publicaciones científicas argentinas de finales de 2012.The aim of this paper is to analyze the degree of compliance on the correct academic writing prefixed words (contained in the new spelling) that perform some scientific journals and technical (and, specifically, the medical field and surgical). This is a work of depth in a previous study (Aguilar Ruiz 2012: 9-12). To do this, we discuss the most frequent errors and misconduct of a corpus of scientific publications Argentine late 2012

El empleo de las nuevas normas ortotipográficas de la lengua española en publicaciones científicas médicas

El objetivo del presente artículo es analizar el grado de cumplimiento de la normativa ortotipográfica académica recogida en la Ortografía de la lengua española (OLE, 2012) que realizan algunas publicaciones periódicas de carácter científico-técnico (y, en concreto, del ámbito médico-quirúrgico). Para ello, comentamos los errores e incorrecciones más recurrentes de un corpus de publicaciones científicas del presente añ