Contribución al conocimiento del yacimiento de yeso de Vilaverd (Tarragona)

El jaciment de guix de Vilaverd (Tarragona) conté les següents espècies minerals: guix, dolomita, quars, bassanita, anhidrita, celestina, calcita (les tres últimes excepcionalment).S'hi han identificat 13 elements químics. En totes les mostres hi ha: Sr, Fe, K, Si, Al. S'ha fet l'anàlisi quantitativa dels 4 primers i, amb els resultats obtinguts, s'ha efectuat l'estudi de la correlació i l'anàlisi factorial. De tot el conjunt de dades hom dedueix que la presència d'argiles és en quantitat inferior a la sensibilitat difractomètrica. L'estronci apareix com a substituent del calci.La menor proporció de Fe i K en els noduls d'alabastre i la llur gran homometria son degudes a una recristal·lització que ha provocat I'expulsió de les argiles

Brayton-Moser Equations and New Passivity Properties for Nonlinear Electro-Mechanical Systems

This paper presents an alternative framework for a practically relevant class of nonlinear electro-mechanical systems. The formalism is based on a generalization of Brayton and Moser’s mixed-potential function. Instead of focusing on the usual energy-balance, the models are constructed using the power flowing through the system. The main objective is to put forth the mixed-potential function as a new building block for modeling, analysis and controller design purposes for electro-mechanical systems

Cross-correlation based high resolution electron backscatter diffraction and electron channelling contrast imaging for strain mapping and dislocation distributions in InAlN thin films

We describe the development of cross-correlation based high resolution electron backscatter diffraction (HR-EBSD) and electron channelling contrast imaging (ECCI), in the scanning electron microscope (SEM), to quantitatively map the strain variation and lattice rotation and determine the density and identify dislocations in nitride semiconductor thin films. These techniques can provide quantitative, rapid, non-destructive analysis of the structural properties of materials with a spatial resolution of order of tens of nanometers. HR-EBSD has a sensitivity to changes of strain and rotation of the order of 10−4 and 0.01° respectively, while ECCI can be used to image single dislocations up to a dislocation density of order 1010 cm−2. In the present work, we report the application of the cross-correlation based HR-EBSD approach to determine the tilt, twist, elastic strain and the distribution and type of threading dislocations in InAlN/AlN/GaN high electron mobility transistor (HEMT) structures grown on two different substrates, namely SiC and sapphire. We describe our procedure to estimate the distribution of geometrically necessary dislocations (GND) based on Nye-Kroner analysis and compare them with the direct imaging of threading dislocations (TDs) by ECCI. Combining data from HR-EBSD and ECCI observations allowed the densities of pure edge, mixed and pure screw threading dislocations to be fully separated

Experimental data on SOA formation from mixtures of anthropogenic and biogenic organic compounds

AbstractSecondary organic aerosols (SOA) constitute a significant fraction of the atmospheric particulate matter. Theses particles are formed as a consequence of the oxidation reaction of certain organic gases that leads to the formation of low-volatility compounds. As for other pollutants, air quality models allow the simulation of particle levels and thus models constitute a powerful tool in air quality management. Nevertheless, the accepted use of models must be based on the validation of its capacity to reproduce observed concentrations. Air monitoring sites provide measured information of a large variety of ambient pollutants. Unfortunately, measurements on SOA are not normally available, as current monitoring networks do not include instrumentation to distinguish primary from secondary sources of organic carbonaceous aerosol. This paper presents a set of photooxidation experiments performed in the European Photorreactor (EUPHORE) smog chamber (CEAM, Spain) under different experimental conditions to investigate SOA formation. The use of chambers allows the isolation of atmospheric chemistry and aerosol formation processes. Thus, although these measurements were obtained at initial precursor concentrations higher than those in atmospheric conditions, they constitute a valuable set of information for SOA model evaluation purposes

AFBC of coal with tyre rubber. Influence of the co-combustion variables on the mineral matter of solid by-products and on Zn lixiviation

The study focuses on the generation and distribution of mineral species in fly and bottom ashes. These were formed during a fluidised co-combustion of a fossil fuel (coal) and a non-fossil fuel (tyre rubber) in a small fluidised bed combustor (7cm x 70cm). The pilot plant had continuous fuel feed using varying ratios of coal and rubber. The study also focuses on the lixiviation behaviour of metallic elements with the assessement of zinc recovering

A comparison of robust polynomial fitting, global geopotential model and spectral analysis for regional–residual gravity field separation in the Doñana National Park (Spain)

Doñana National Park is a protected area of approximately 500 km2 located on the SW coast of Spain with singular and interesting ecological and geological features. A gravimetric survey is presented where L&R gravity metres were used in the gravimetric observations with GPS and high-precision levelling positioning. Bouguer gravity anomalies were computed and least squares prediction was used for gross-error detection. Robust polynomial fitting, the recent EGM2008 global geopotential model (complete to degree and order 2159), and spectral analysis were tested for regional–residual gravity field separation. A detailed description of the gravimetric characteristics of the Doñana National Park is presented and the values of residual gravity anomalies were correlated with geological features, where the use of the EGM2008 global geopotential model has revealed an interesting tool for regional–residual gravity field separation. Finally, the interpretation of the results is justified by the well-known geological aspects of the park, but some modifications in the boundaries of the different geological features are needed in order to fit the modelled gravity with the residual gravity anomalies in the two cross-sections analysed.The studies presented here were part of CICYT (Spanish Research Directorate) research project nos. HID 97-0321 and REN2001-1293. We would like to thank all UPC members participating in these projects and the staff from the Biological Station of Donana (CSIC), Palacio de Donana and Donana National Park. We remain deeply grateful for the fruitful discussion with Dr. Salvany and for the geological review of the manuscript.Martín Furones, ÁE.; Nuñez Andrés, M.; Gili, J.; Anquela Julián, AB. (2011). A comparison of robust polynomial fitting, global geopotential model and spectral analysis for regional–residual gravity field separation in the Doñana National Park (Spain). Journal of Applied Geophysics. 75(2):327-337. https://doi.org/10.1016/j.jappgeo.2011.06.037S32733775