Empiricism and stochastics in cellular automaton modeling of urban land use dynamics

An increasing number of models for predicting land use change in regions of rapidurbanization are being proposed and built using ideas from cellular automata (CA)theory. Calibrating such models to real situations is highly problematic and to date,serious attention has not been focused on the estimation problem. In this paper, wepropose a structure for simulating urban change based on estimating land usetransitions using elementary probabilistic methods which draw their inspiration fromBayes' theory and the related ?weights of evidence? approach. These land use changeprobabilities drive a CA model ? DINAMICA ? conceived at the Center for RemoteSensing of the Federal University of Minas Gerais (CSR-UFMG). This is based on aneight cell Moore neighborhood approach implemented through empirical land useallocation algorithms. The model framework has been applied to a medium-size townin the west of São Paulo State, Bauru. We show how various socio-economic andinfrastructural factors can be combined using the weights of evidence approach whichenables us to predict the probability of changes between land use types in differentcells of the system. Different predictions for the town during the period 1979-1988were generated, and statistical validation was then conducted using a multipleresolution fitting procedure. These modeling experiments support the essential logicof adopting Bayesian empirical methods which synthesize various information aboutspatial infrastructure as the driver of urban land use change. This indicates therelevance of the approach for generating forecasts of growth for Brazilian citiesparticularly and for world-wide cities in general

Structural studies and influence of the structure on the electrical and optical properties of microcrystalline silicon thin films produced by RF sputtering

Microcrystalline silicon thin films were produced by reactive magnetron sputtering on glass substrates under several different conditions (RF power and gas mixture composition). The film structure was studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM) and Raman spectroscopy, allowing the determination of crystal sizes, crystallinity and mechanical strain. These parameters were evaluated by fitting a pseudo-Voigt function to the X-ray data, and by the application of the strong phonon confinement model to the Raman spectra. The degree of crystallinity and the presence of single crystals or crystal agglomerates, which was confirmed by TEM, depends on the preparation conditions, and strongly affects the optical spectra and the electrical transport properties.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XX

Optical modulation spectroscopy of hydrogenated microcrystalline silicon

The properties of microcrystalline silicon thin films prepared by RF sputtering were investigated by optical modulation spectroscopy at room temperature and the results were correlated with Raman and conductivity measurements. For comparative purposes, a number of good quality PECVD microc-Si:H samples were also investigated. For PECVD samples the OMS signal is very weak, and only measurable for probe beam energies comparable to the gap of amorphous silicon. This indicates the absence of gap states and therefore a very high crystalline fraction, as confirmed by Raman and TEM measurements. In what concerns RF-sputtered samples, different behaviors can be distinguished: Some samples show a low OMS signal which can be attributed either to a high crystallinity (low density of gap states) or to high recombination rates. These two cases can be distinguished by electrical conductivity values and analysis of the Raman spectra. Other samples exhibit a OMS signal similar to a-Si:H and have low conductivity values, consistent with a Raman spectrum typical of a-Si:H.FCT-grant from PRAXIS XX

Crystal size and crystalline volume fraction effects on the Erbium emission of nc-Si:Er grown by r.f. sputtering

Erbium-doped low-dimensional Si films with different microstructures were grown by reactive magnetron sputtering on glass substrates by varying the deposition parameters. Their structure and chemical composition were studied by micro-Raman and Rutherford backscattering spectrometry, respectively. In this contribution the Erbium emission is studied as a function of nanocrystalline fraction and average crystal sizes and also as a function of the matrix chemical composition. We discuss the temperature dependence of the Er3+ emission as well as the possible explanations of the low Er active fraction.FCT (POCTI/CTM/39395) and INTAS Project #03-51-6486

Películas a base de proteínas de salvado de arroz enriquecidas por el extracto fenólico de salvado de arroz fermentado y por la arcilla montmorillonítica

Proteins extracted from rice bran were used to prepare bio-base films where a factorial experimental design was performed in order to evaluate the effect of protein and glycerol concentrations, and the addition of phenolic extract and montmorillonite (MMT) clay on their physicochemical properties. The phenolic extract was obtained from fermentation of rice bran in solid state with the fungus Rhizopus oryzae. Results showed that protein concentration affected (p < 0.05) the luminosity, opacity and solubility of the films. An increase of glycerol concentration strongly affects (p < 0.05) the values of mechanical properties and water vapor permeability of the films. The addition of phenolic extract to the films affected (p < 0.05) opacity, tensile strength, elongation, Youngs modulus and water vapor permeability, while addition of MMT decreased (p < 0.05) the mechanical properties of the films. Films presented solubility values of less than 25%, luminosity above 80 (L*), opacity above 14%, tensile strength of 8.6 MPa, elongation of 70%, elasticity above 600 MPa and water vapor permeability of 7.5 g.mm/d.m2.kPa. These results show that rice bran protein can be used in the production of bio-based films to further use in food applications.Con el fin de evaluar el efecto que sobre las propiedades fisicoquímicas de las proteínas extraídas del salvado de arroz tienen distintas concentraciones de proteína y de glicerol, así como la adición de extracto fenólico y de arcilla montmorillonítica, las mismas se utilizaron para preparar películas de base biológica en el marco de un diseño experimental factorial. Mediante la fermentación de salvado de arroz en estado sólido con el hongo Rhizopus oryzae, se obtuvo el extracto fenólico. Los resultados demuestran que la concentración proteica afectó significativamente (p < 0,05) la luminosidad, la opacidad y la solubilidad de las películas. Asimismo, un aumento de la concentración de glicerina afectó fuertemente (p < 0,05) los valores de las propiedades mecánicas y de la permeabilidad al vapor de agua de las mismas. La adición de extracto fenólico a las películas afectó de manera significativa (p < 0,05) la opacidad, la fuerza de tensión, el alargamiento, el módulo de Young y la permeabilidad al vapor de agua, mientras que la adición de montmorillonita disminuyó (p < 0,05) sus propiedades mecánicas. Se constató que las películas mostraron valores de solubilidad inferiores a 25%, de luminosidad superiores a 80 (L*), de opacidad superiores a 14%, de fuerza de tensión de 8,6 MPa, de alargamiento de 70%, de elasticidad superiores a 600 MPa y de permeabilidad al vapor de agua de 7,5 g.mm/d.m2 .kPa. Estos resultados demuestran que, en el ámbito de los alimentos, la proteína de salvado de arroz puede utilizarse para la producción de películas de base biológica con el fin de adjudicarle usos adicionales.Authors Cristiano G. Schmidt and Miguel A. Cerqueira are thankful to Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil; BEX 9730/11-7) and Fundacao para a Ciencia e Tecnologia, POPH-QREN and FSE (FCT, Portugal) (SFRH/BPD/72753/2010) for financial support. The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF.NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON. 2 - O Novo Norte), QREN, FEDER

Surface plasmon resonance of sparsely dispersed au nanoparticles in TiO2 photoanode of dye sensitised solar cells

Plasmonics is an emerging field that makes use of the nanoscale properties of metals, and its application in solar cells has seen a recent surge of interest [1]. Dye-sensitized solar cells (DSSC) were fabricated by incorporating Au NPs into the TiO2 photoanode. The dye absorption is enhanced by the strong localized electric field from localized surface plasmon and the recombination and back reaction of electrons in DSSC is suppressed by depositing a thin TiO2 blocking layer over the TiO2:Au electrode. An increase in photoresponse was observed in the visible region with TiO2:Au electrode. In particular, we report the observation that a nanoparticles of a noble metal (Au) placed on top of the n-type widegap TiO2 that control the light emission angle can increase the short circuit current density and the quantum efficiency of the cell.FCT (Fundação para a Ciência e Tecnologia) for funding through the Ciencia 2007 programme and the pluriannual contract with CFUM and the European Commission through FP7-PEOPLE-2010-IRSES-NanoCIS (269279