Effect of the interactive simulations on students’ conceptions about simple harmonic movement

Muchos alumnos universitarios mantienen concepciones equivocadas acerca del movimiento armónico simple (MAS). Se ha podido comprobar que, en relación con él, mantienen una visión lineal que las simulaciones informáticas, a pesar de facilitar la comprensión de los conceptos físicos, no han podido modificar. Entre los alumnos investigados se han podido distinguir tres etapas en la conceptualización del movimiento armónico simple: una primera “temprana” en la que aún no se comprende el significado de las magnitudes que describen el fenómeno (periodo, amplitud,..) y responden guiados por la intuición, una segunda “lineal” en la que, a pesar de usar con propiedad esas magnitudes, se razona como si el movimiento fuera uniforme, y una tercera “sinusoidal”, coherente con el conocimiento físico establecido.Many university students have misconceptions about simple harmonic movement (HSM). It has been observed that they have a linear vision that computer simulations have been unable to shift, despite helping them to understand physical concepts. Among those students investigated, there occur three stages in the conceptualization of simple harmonic movement: a first, “premature” stage in which they still have not grasped the meaning of the magnitudes that describe the phenomenon (period, amplitude…), and their response is guided by intuition; a second “linear” stage in which, although these magnitudes are used properly, they reason as if the movement was uniform; and a third “sinusoidal” stage that is coherent with established physical knowledge

Constructivist learning environments based on computerized simulations

El paradigma educativo de la nueva sociedad de la información se caracterizará por modelos constructivistas de aprendizaje y entornos enriquecidos tecnológicamente. En un entorno constructivista de aprendizaje basado en applets Java, los estudiantes pueden resolver problemas apoyados por el ordenador. Las simulaciones interactivas contribuyen al proceso de enseñanza/aprendizaje de la física de diferentes maneras: los estudiantes visualizan fenómenos naturales, se modifica la secuencia habitual de enseñanza y se evitan dificultades con las matemáticas.The educative paradigm of the new information society will be characterized by constructivistic models of learning and enriched technologically environments. In the constructivistic environments of learning based on Java applets, students can solve problems supported by the computer. Interactive simulations aid the teaching and learning of Physics in different ways: students visualize natural phenomena, change the habitual sequences of learning and avoid difficulties with mathematics

Study of the thermal decomposition of petrochemical sludge in a pilot plant reactor

The pyrolysis of a sludge produced in the waste water treatment plant of an oil refinery was studied in a pilot plant reactor provided with a system for condensation of semivolatile matter. The study comprises experiments at 350, 400, 470 and 530 °C in nitrogen atmosphere. Analysis of all the products obtained (gases, liquids and chars) are presented, with a thermogravimetric study of the char produced and analysis of main components of the liquid. In the temperature range studied, the composition of the gas fraction does not appreciably vary. In the liquids, the light hidrocarbon yield increases with increasing temperature, whereas the aromatic compounds diminish. The decomposition of the solid fraction has been analysed, finding a material that reacts rapidly with oxygen regardless of the conditions it is formed.TEP-6686 project funded by the Operational Program FEDER and FSE of Andalusia 2007-2013. Ministry of Education and Science (Spain): CTQ2008-05520. Valencian Community Government (Spain): PROMETEO/2009/043 and ACOMP2011/224

Thermogravimetric monitoring of oil refinery sludge

The present work has two dimensions: analytical and environmental. On the one hand we proved that thermogravimetric analysis can be used to perform fast characterization of oil refinery sludge. To this end, thermogravimetric curves were deconvoluted by using autocatalytic kinetics to take into account acceleratory phases in a thermal degradation performed in oxygen-containing atmosphere or at high heating rates. Based on thermogravimetric results, oil refinery sludge was modeled in terms of various fractions (pseudo-components) which degrade as major oil cuts. On the other hand, as an alternative to landfill, we have seen that Soxhlet extraction allows recovery almost half of the weight of sludge as a mixture of hydrocarbons, similar to gas–oil, which burns without residue. This ensures both, waste inerting and significant reduction in sludge volume.This work was funded by Junta de Andalucía, Spain (Project TEP–6688)

Gas production during the pyrolysis and gasification of biological and physico-chemical sludges from oil refinery

Pyrolysis and gasification of two different sludges coming from a Spanish refinery have been performed at different experimental conditions. A physico-chemical (PC) and a biological (BIO) sludge have been studied. Runs at different heating rates (approx. 4 and 10 K/s) and with different contact time between gases and decomposed sludge have been performed. In general, the ratio H2/CO is higher in pyrolytic runs. The highest ratio is obtained in the pyrolysis at low heating rate and parallel flow, using both sludges. The maximum emission of CO, i.e. the worst combustion conditions, is given in the runs where contact time is minimized and at high heating rates.Support for this work was provided by Junta de Andalucía, Spain (project TEP-6688) and the Generalitat Valenciana, Spain, with projects Prometeo/2009/043/FEDER and ACOMP2011/224, and by the Spanish MCT CTQ2008-05520

Variations in Production and Oligomers Content Obtained Under Hydrothermal Treatment Among Five Fast-Growing Species

In order to identify fast growing species utilizable for olygomer and monomer production, five fast growing species (Paulownia fortunei, Chamaecytisus proliferus, Arundo donax, Leucaena.diversifolia and Sesbania grandiflora) were tested. Concurrently, the biomass productivity of these species was also tested on a field scale. The biomass productivity of the selected species studied ranges from 0.36 to 21.30 t ha �1 (o.d.b.) under Mediterranean conditions for the year 1 sprouts. In addition, the hydrothermal treatment results show that the selected species could be employed as alternative raw material for the production of oligomers, leading to a high concentration of oligomers (9.4-23.4 g/L -1 at 190ºC