Anisotropic Conductive Adhesives for Interdigitated Back Contact (IBC) Silicon Solar Cells

The current manufacturing process for solar panels using interdigitated back contact (IBC) silicon solar cells involves a multi-step metallization and interconnection process in which a substantial amount of silver is used. This work focuses on a new process using conductive adhesives (CA) which would increase efficiency and lower cost through a one-step metallization and interconnection process that combines with encapsulation using little silver and only requiring metal patterning on the back sheet or back glass. It would also not require direct metallization of the silicon, which would result in fewer defects, while increasing voltage and therefore efficiency. Silver-coated Poly(Methyl Methacrylate) Microsphere (AgMS) and indium powder are the primary materials used as the conductive particles in an ethyl vinyl acetate (EVA)/toluene adhesive. The CA is prepared by mixing the components in toluene. The resulting mixture is used to produce 300μm thick CA sheets using a universal applicator, cut into pieces, and pressed between a piece of glass with coplanar Ag electrodes and a silicon wafer at varying temperatures and pressures. This yields ~3 Ωcm2 for both the AgMS and indium fillers. Significantly lower values are required for the target application, and possible new approaches in attaining lower resistivity are discussed

Inventario de recursos hídricos en espacios adehesados de Extremadura mediante técnicas SIG

El agua es un recurso natural imprescindible para la vida y para el desarrollo de las actividades económicas. En áreas de clima mediterráneo su disponibilidad es muy variable en el espacio y en el tiempo, debido, por un lado, a la irregularidad de las precipitaciones y, por otro, a la presencia regular de veranos secos y ocasional de periodos prolongados de sequía, lo que la hace ser un bien valioso que ha de ser gestionado correctamente. En esta comunicación se exponen trabajos realizados por el GIGA (Grupo de Investigación Geoambiental de la Universidad de Extremadura) con distintas aplicaciones ambientales en los que fue necesario llevar a cabo un inventario de recursos hídricos en fincas de gestión privada de espacios adehesados dedicadas a la ganadería extensiva. Para ello se han utilizado procedimientos metodológicos basados en SIG (Sistemas de Información Geográfica) usando información cartográfica digital fácilmente asequible como los MTN (Mapa Topográfico Nacional) a escala 1:10.000 e imágenes aéreas del SIGPAC (Sistema de Información Geográfica de Parcelas Agrícolas) con el objetivo de generalizar una metodología que permita un proceso continuo de recopilación y seguimiento de los recursos hídricos que se disponen, aplicable a diferentes escalas espaciales: finca, municipio, provincia, comunidad autónoma, etc.Water is a natural resource essential to life and development of economic activities. In Mediterranean type climate areas its availability is very variable in space and time due to, first , erratic rainfall and, secondly, the regular presence of dry summers and occasional long interannual drought periods that makes it a valuable asset that must be managed properly. This paper shows works done by GIGA (GeoEnvironmental Research Group, University of Extremadura, Spain) with different environmental applications in which it was necessary to conduct an inventory of water resources in privately owned ranching farms in dehesa land system. Methodological procedures based on GIS (Geographical Information Systems) were used working with digital map information readily available as MTN (National Topographic Map) sheet at 1:10.000 scale and aerial images of SIGPAC (Geographical Information System of Farming Land of Spanish Environment Ministry) in order to generalize a methodology that allows a continuous process of collecting and monitoring water resources applicable at different spatial scales: farm, municipality, province, region, etc

Changes in Land Management of Iberian Rangelands and Grasslands in the Last 60 Years and their Effect on Vegetation

Rangelands and grasslands occupy now more than 3 million ha in the Iberian Peninsula representing one of the most valuable ecosystems. They are particularly interesting due to their great geographical spread and heterogeneity in land management. Significant changes have been undergone in the last 60 years affecting vegetation. The main goal in this study was to compile existing information about the changes in the Iberian rangelands and grasslands, their geographical distribution, typologies, main characteristics as well as past and recent land management based on a thorough bibliographical review and serious research. This has been subdivided into five large groups according to climate and human drivers: (1) Mediterranean rangelands and steppes, (2) oceanic grasslands, (3) mountainous meadows, (4) semi-arid steppes and (5) Portuguese rangelands and grasslands. Two milestones over the past 60 years were remarkable as main driving forces: rural exodus in the 1960s and 1970s and Spain and Portugal joining the European Union in 1986. They have provoked both processes of intensification and extensification at the same time on different scales. Many farms have been progressively fragmented using wire fences, and the numbers of livestock have been significantly increased. Land abandonment and grazing exclusion have provoked a large shrub encroachment of species such as Retama sphaerocarpa or Cistus ladanifer

La fotografía aérea en España y su aplicabilidad al seguimiento y la estimación de la erosión por flujo concentrado

Son numerosos los trabajos que muestran la creciente preocupación por los procesos de erosión hídrica por flujo concentrado en los países mediterráneos en los últimos años. Los métodos y técnicas existentes para el seguimiento y cuantificación de la erosión hídrica por flujo concentrado son muy diversos, resultando de especial interés, relevancia y potencial aquellos relacionados con las modernas tecnologías geoespaciales (sistemas de posicionamiento global diferenciales, equipos laser terrestres o aerotransportados, fotogrametría digital aérea y terrestre, etc.). Sin embargo, la utilización de dichas técnicas en numerosas ocasiones se encuentra limitada por la fecha de aparición del instrumental, por tanto, algunas fuentes históricas son todavía necesarias para comprender la evolución a medio y largo plazo de las formas de erosión por flujo concentrado. Sin embargo, en ocasiones, la localización de las fotografías aéreas existentes para una determinada zona puede resultar laboriosa y tediosa lo que da lugar a grandes pérdidas de tiempo en los proyectos y equipos de investigación. Por todo ello, los principales objetivos del presente trabajo son i) presentar una guía respecto al material fotográfico aéreo disponible para España, ii) resumir sus características principales y iii) analizar su utilidad para el seguimiento y cuantificación de la erosión ocasionada por flujo concentrado.Erosion produced by concentrated water flow has been highlighted as an important soil degradation phenomenon in the Mediterranean catchment. Several kinds of methodologies and techniques have been used indeed in order to monitor and quantify erosion produced by concentrated flow, mainly those related with modern geospatial technologies (DGPS, LIDAR, LTS, aerial and terrestrial photogrammetry, etc.). However the time scale of the studies based exclusively on modern techniques is constrained by the date of appearance of those techniques. Therefore, some historical sources are still necessary in gully erosion studies (medium, short time scale). Sometimes, however, finding these documents is laborious and tedious, being the researchers forced to spend a lot of time in localizing and acquiring it. Therefore, the main objectives of this work are i) to provide a guidance regarding the available aerial photographs and orthophotographs for rill and gully erosion studies in Spain and covering the whole country, ii) to summarize the main characteristics of these materials and iii) to analyze the suitability of using these materials for soil loss monitoring and assessment produced by concentrated flow

Studying the influence of livestock pressure on gully erosion in rangelands of SW Spain by means of the UAV+SfM workflow

Gully erosion in agrosilvopastoral systems of SW Spain represents a common degradation process, but has been hardly analysed. The suitability of using the Unmanned Aerial Vehicles (UAV) and Structure from Motion photogrammetry (SfM) workflow to map small valley-bottom gullies in these landscapes was tested. The results showed centimetre-level accuracy. Observed strengths and limitations of the UAV+SfM workflow in the study areas are discussed. The resulting cartography allowed mapping soil erosion forms at outstanding spatial scales. All study areas showed evidences of degradation

Effect of Functional Group and Carbon Chain Length on the Odor Detection Threshold of Aliphatic Compounds

Odor detection thresholds (ODTs) are used for assessing outdoor and indoor air quality. They are obtained experimentally by olfactometry and psychophysical methods, and large compilations are available in the literature. A non-linear regression equation was fitted to describe the ODT variability of 114 aliphatic compounds based on the alkyl chain length for different homologous series (carboxylic acids, aldehydes, 2-ketones, esters, 1-alcohols, amines, thiols, thioethers and hydrocarbons). The resulting equation reveals an effect of the functional group, molecular size and also an interaction between both factors. Although the mechanistic interpretation of results is uncertain, the relatively high goodness-of-fit (R2 = 0.90) suggests that ODT values of aliphatic compounds can be predicted rather accurately, which is not the case for rigid molecules. This equation may serve as a basis for the development of more complex ODT models taking into account diverse structural features of odorants. The variability of power-law exponents was also investigated for the homologous series

Reduction of the frequency of herbaceous roots as an effect of soil compaction induced by heavy grazing in rangelands of SW Spain

Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily grazed areas. Nevertheless, a better understanding of how soil compaction affects grass production is still needed. In this study, some of the effects of soil compaction due to heavy grazing are analysed, mainly the reduction of the frequency of herbaceous roots and its relationships with bulk density and soil penetration resistance. The study was carried out in 22 fenced areas grazed under different intensities (animal stocking rates: 0.19-15.76 AU ha−1). Undisturbed soil core and bulk samples were collected at 3 depth intervals in order to determine select soil properties (texture, organic matter content, and bulk density). Additionally, soil penetration resistance was quantified at 890 random points at different depths and soil moisture contents. Frequency of herbaceous roots was estimated for each soil horizon in 47 soil profiles and categorized into 4 classes: none, few, common and many. Results showed negative relationships between bulk density (> 10 cm depth) and the content of soil organic matter from 0 to 5 cm (r =−0.061, p < 0.05) and 5-10 m depth (r = −0.824, p < 0.005). Furthermore, a tendency for decreasing mean values of soil penetration resistance as the frequency of herbaceous roots increased was also observed. The values observed confirm that soil compaction provoked by an excessive number of animals reduced the quantity of herbaceous roots. The value of 2 MPa traditionally accepted as restrictive for root growth is discussed. Findings presented here could be of interest for policy makers and farm owners to guide decisions about optimum animal stocking rates

Organ-focused mutual information for nonrigid multimodal registration of liver CT and Gd–EOB–DTPA-enhanced MRI

Accurate detection of liver lesions is of great importance in hepatic surgery planning. Recent studies have shown that the detection rate of liver lesions is significantly higher in gadoxetic acid-enhanced magnetic resonance imaging (Gd–EOB–DTPA-enhanced MRI) than in contrast-enhanced portal-phase computed tomography (CT); however, the latter remains essential because of its high specificity, good performance in estimating liver volumes and better vessel visibility. To characterize liver lesions using both the above image modalities, we propose a multimodal nonrigid registration framework using organ-focused mutual information (OF-MI). This proposal tries to improve mutual information (MI) based registration by adding spatial information, benefiting from the availability of expert liver segmentation in clinical protocols. The incorporation of an additional information channel containing liver segmentation information was studied. A dataset of real clinical images and simulated images was used in the validation process. A Gd–EOB–DTPA-enhanced MRI simulation framework is presented. To evaluate results, warping index errors were calculated for the simulated data, and landmark-based and surface-based errors were calculated for the real data. An improvement of the registration accuracy for OF-MI as compared with MI was found for both simulated and real datasets. Statistical significance of the difference was tested and confirmed in the simulated dataset (p < 0.01)