Application of Wignner-Ville distribution to identify anomalies in GPR profiles

Con base en la Distribución de Wigner-Ville(WVO) se realizó un análisis en tiempo y frecuencia de datos obtenidos con el Radar de Penetración Terrestre (GPR), basado en el estudio de la descomposición de la señal espectral. Se calcula una correlación entre la señal original y las componentes de tiempo-frecuencia para obtener anomalías estructurales de la información contenida en el radargrama relacionándola con la geología disponible. En primer lugar se describe la aplicación de un ejemplo teórico constituido por lo que representaría un túnel (tubería). Se obtuvieron las firmas correspondientes en el dominio del tiempo y en el dominio de la frecuencia. Finalmente se analiza esta metodología en un sido de prueba en la detección de un tambo enterrado donde son conocidas la geometría y su profundidad. Este especial sitio fue facilitado por la Universidad Nacional Autónoma de México, en los terrenos del Observatorio Magnético de Teoloyucan, Estado de México. Los resultados obtenidos son bastante alentadores, ya que la WVD es capaz de definir los rasgos morfofógicos relacionados con el tambo y abre la posibilidad de localizar este tipo de estructuras.

Participatory modelling to support decision making in water management. A case study in the middle Guadiana basin, Spain.

The objective of this research was the implementation of a participatory process for the development of a tool to support decision making in water management. The process carried out aims at attaining an improved understanding of the water system and an encouragement of the exchange of knowledge and views between stakeholders to build a shared vision of the system. In addition, the process intends to identify impacts of possible solutions to given problems, which will help to take decisions.

Image sub-segmentation by PFCM and Artificial Neural Networks to detect pore space in 2D and 3D CT soil images

The image by Computed Tomography is a non-invasive alternative for observing soil structures, mainly pore space. The pore space correspond in soil data to empty or free space in the sense that no material is present there but only fluids, the fluid transport depend of pore spaces in soil, for this reason is important identify the regions that correspond to pore zones. In this paper we present a methodology in order to detect pore space and solid soil based on the synergy of the image processing, pattern recognition and artificial intelligence. The mathematical morphology is an image processing technique used for the purpose of image enhancement. In order to find pixels groups with a similar gray level intensity, or more or less homogeneous groups, a novel image sub-segmentation based on a Possibilistic Fuzzy c-Means (PFCM) clustering algorithm was used. The Artificial Neural Networks (ANNs) are very efficient for demanding large scale and generic pattern recognition applications for this reason finally a classifier based on artificial neural network is applied in order to classify soil images in two classes, pore space and solid soil respectively.

Meta-analysis of strategies to control nitrate leaching in irrigated agricultural systems and their effects on crop yield.

Nitrate leaching (NL) is an important N loss process in irrigated agriculture that imposes a cost on the farmer and the environment. A meta-analysis of published experimental results from agricultural irrigated systems was conducted to identify those strategies that have proven effective at reducing NL and to quantify the scale of reduction that can be achieved. Forty-four scientific articles were identified which investigated four main strategies (water and fertilizer management, use of cover crops and fertilizer technology) creating a database with 279 observations on NL and 166 on crop yield. Management practices that adjust water application to crop needs reduced NL by a mean of 80% without a reduction in crop yield. Improved fertilizer management reduced NL by 40%, and the best relationship between yield and NL was obtained when applying the recommended fertilizer rate. Replacing a fallow with a non-legume cover crop reduced NL by 50% while using a legume did not have any effect on NL. Improved fertilizer technology also decreased NL but was the least effective of the selected strategies. The risk of nitrate leaching from irrigated systems is high, but optimum management practices may mitigate this risk and maintain crop yields while enhancing environmental sustainability.