El método argumental en la investigación geográfica: su proceso evolutivo.

Sin resume

Madrid, metrópoli global

Sin resume

El profesor Manuel de Terán

Sin resume

Internacionalización de la economía española: el ejemplo de la CAM.

Sin resume

Fluidization of Group B particles with a rotating distributor

A novel rotating distributor fluidized bed is presented. The distributor is a rotating perforated plate, with 1% open-area ratio. This work evaluates the performance of this new design, considering pressure drop, Δp, and quality of fluidization. Bed fluidization was easily achieved with the proposed device, improving the solid mixing and the quality of fluidization. In order to examine the effect of the rotational speed of the distributor plate on the hydrodynamic behavior of the bed, minimum fluidization velocity, Umf, and pressure fluctuations were analyzed. Experiments were conducted in the bubbling free regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart's classification. The pressure drop across the bed and the standard deviation of pressure fluctuations, σp, were used to find the minimum fluidization velocity, Umf. A decrease in Umf is observed when the rotational speed increases and a rise in the measured pressure drop was also found. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess gas velocities. Measurements with several initial static bed heights were taken, in order to analyze the influence of the initial bed mass inventory, over the effect of the distributor rotation on the bed hydrodynamics.Publicad

Resolver situaciones problemáticas en genética para modificar las actitudes relacionadas con la ciencia

Las actitudes como contenido escolar son difíciles a la hora de enseñar y de valorar su nivel de adquisición. En este estudio nos centramos en las actitudes sobre la ciencia como conocimiento y hacia la ciencia como asignatura académica. Presentamos los resultados de una investigación comparativa realizada con alumnos de 4º de educación secundaria obligatoria (15-16 años) que se acercaron a la genética desde dos perspectivas distintas, una metodología tradicional para el grupo control y una unidad didáctica basada en la resolución de situaciones problemáticas, «¿Soy así por puro azar?», para el experimental. Al fi nalizar el proceso de enseñanza-aprendizaje, el grupo control mantuvo sus actitudes iniciales mientras que el experimental manifestó actitudes más favorables y realistas sobre y hacia la ciencia.Attitudes as scholar content are diffi cult to teach and their level of acquisition is diffi cult to assess. In this study we focus on attitudes about Science as knowledge and towards Science as academic subject. We present the results of a comparative investigation carried out with students of fourth level of Obligatory Secondary Education (15-16 years) who approached Genetics from two different perspectives, a traditional methodology for the control group and a didactic unit based on the resolution of problematic situations, «Am I like this by pure chance?», for the experimental one. At the end of the teaching-learning process the control group maintained its initial attitudes while the experimental one showed realistic and more favourable attitudes about and toward Science

Dimensión territorial de la globalización económica

Economic globalization, joined to complex processes between which individualized the sectorial interaction of a global scale through denominated way of flexible production, capital movements, international trade, and technological changes, reach several territorial expressions modelled by the irruption of the globalization process. In this paper, we analyzes the distribution of this aspects in the great world regions, trying to explain the territory role-playing, constituted and building by natural, cultural, social, politic and economic characteristics in history, in order to acquire relevance or marginalization of these global processes. These actors are individualized, can also contribute to transformation of the territory and, especially, are responsible for public policies. In this territorial dimension of economic globalization, the market and the public institutions also have a significant role.Étant le résultat de processus complexes tels que l ´interaction à échelle mondiale, la valeur de la production et les changements téchnologiques, la globalisation économique a une manisfestation territoriale très différente. Cet article veut déterminer le rôle du territoire quand il s´agit d´assumer un protagonisme ou un rejet vis à vis de ces processus globaux à differentes échelles , en relation avec les bases indispensables pour participer activement à ceux çi , tout en considérant les acteurs qui peuvent les déterminer , espéciallement ceux qui définissent les politiques publiques. Dans cette dimension territoriale de la globalisation économique et à un niveau théorique s´unissent le marché et l´action de État.La globalización económica vinculada a unos procesos complejos entre los que se individualizan la interacción sectorial a escala mundo a través del denominado modo de producción flexible, los movimientos del capital, el comercio internacional y los grandes cambios tecnológicos tiene una expresión territorial muy diferente. El presente artículo, que analiza la distribución de esas facetas en las grandes regiones mundiales, trata de explicar el papel que juega el territorio constituido y construido por elementos naturales, culturales, sociales, políticos y económicos a lo largo de la historia, a la hora de adquirir una significación o una marginación en dichos procesos globales. A su vez se individualizan aquellos actores que pueden contribuir a la transformación de un territorio, o de algunos procesos actuales, especialmente los responsables de las políticas públicas. Esta dimensión territorial de la globalización económica a un nivel teórico, trata de aunar el papel y el comportamiento del mercado con las acciones propias de las instituciones públicas

Performance of a LiBr water absorption chiller operating with plate heat exchangers

This paper studies the performance of a lithium bromide water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from 75°C to 105°C. In the condenser and the absorber, the inlet temperature of the cooling water goes from 20°C to 40°C. The coefficient of performance (COP) obtained ranges from 0.5 to 0.8 for cooling duties ranging from 2 kW to 12 kW. The chiller response to different hot fluid temperatures and circulated mass flow rates is also presented. The performance and the internal parameters of the chiller at part load are, therefore, calculated. A higher efficiency results when the solution pumped from the absorber to the desorber decreases. The heat transfer analysis of the PHEs is also presented. The overall heat transfer coefficient in the desorber, equal to 790 W/m²K at the design conditions, is also analysed at part load. The condenser performance can be represented by a similar relationship found in conventional air cooled condensersThis work was partially funded by CICYT Ministerio de Ciencia y Tecnología (CLIMABCAR project no. DPI 2003-01567)Publicad