Porous Soil Structure as Heterogeneous Complex Networks

In this paper we present a complex network model based on a heterogeneous preferential attachment scheme as a new way to quantify the porous structure of soils and to relate them with soil texture. We consider the pores as nodes, the properties of which, such as position and size, are described by fixed states in a metric space. An affinity function is introduced to bias the attachment probabilities of links according to these properties. We perform an analytical study of the degree distributions in the model and develop a numerical analysis of the degree distributions in the model for a combination of parameters corresponding to eleven empirical soil samples with different physical properties and five different textures

A Program for Fractal and Multifractal Analysis of Two-Dimensional Binary Images. Computer Algorithms versus Mathematical Theory.

In this paper we present a tool to carry out the multifractal analysis of binary, two-dimensional images through the calculation of the Rényi D(q) dimensions and associated statistical regressions. The estimation of a (mono)fractal dimension corresponds to the special case where the moment order is q = 0

Sum Insured Determination for Cereal, Citrus and Vineyards in the Spanish Agricultural Insurance System.

In general, insurance is a form of risk management used to hedge against a contingent loss. The conventional definition is the equitable transfer of a risk of loss from one entity to another in exchange for a premium or a guaranteed and quantifiable small loss to prevent a large and possibly devastating loss being agricultural insurance a special line of property insurance. Agriculture insurance, as actually are designed in the Spanish scenario, were established in 1978. At the macroeconomic insurance studies scale, it is necessary to know a basic element for the insurance actuarial components: sum insured. When a new risk assessment has to be evaluated in the insurance framework, it is essential to determinate venture capital in the total Spanish agriculture. In this study, three different crops (cereal, citrus and vineyards) cases are showed to determinate sum insured as they are representative of the cases found in the Spanish agriculture. Crop sum insured is calculated by the product of crop surface, unit surface production and crop price insured. In the cereal case, winter as spring cereal sowing, represents the highest Spanish crop surface, above to 6 millions of hectares (ha). Meanwhile, the four citrus species (oranges, mandarins, lemons and grapefruits) occupied an extension just over 275.000 ha. On the other hand, vineyard target to wine process shows almost one million of ha in Spain

Multifractal analysis of the pore- and solid-phases in binary two-dimensional images of natural porous structures

We use multifractal analysis (MFA) to investigate how the Rényi dimensions of the solid mass and the pore space in porous structures are related to each other. To our knowledge, there is no investigation about the relationship of Rényi or generalized dimensions of two phases of the same structure

Incidencia de los Robos y Hurtos en el Sistema de Seguros Agrarios Español.

Este trabajo se estudia la viabilidad técnica de incorporar al actual Sistema de Seguros Agrarios Español la cobertura de los robos y hurtos en el medio rural, calculando la prima pura base (Ppb) para todas las producciones agrícolas, ganaderas y medios de producción asegurables dentro del sistema de los Seguros Agrarios Combinados. Los resultados indican que los robos se producen con una mayor influencia sobre los elementos de los riegos por aspersión y de los invernaderos, y la Ppb en consecuencia es la más alta de todos los bienes asegurables. Les siguen en importancia las explotaciones de ganado ovino-caprino y, en cuanto a las producciones agrícolas, destaca el olivar

Agriculture in a changing climate : Preface

Agriculture is an economic sector that is particularly sensitive to weather. Recent meteorological events have reduced crop production in different parts of the world. Weather extremes resulting from climate change are projected to increase, making crop production more vulnerable and ultimately threatening food security. A continuing effort to develop scientific knowledge in climate and agriculture will help to manage risks and opportunities in these fields. This special issue of Climate Research represents a collection of studies that contribute to the general understanding of weather-related risks and climate impacts on agricultural system

Election of Water Resources Management Entity Using a Multi-Criteria Decision (MCD) Method in Salta Province (Argentine)

At present, the water resources are a strategic element each time more necessary and limited becoming a source of conflicts. For that, it is fundamental to create an independent and competent entity with good reputation and social acceptation. This entity must be able to obtain, store and process all data dispersed in different entities creating a network for these purposes. Finally, it must be able to organize different branches between the government and the final users. Using one of the wellknown Multicriteria Decision Methods(MCDM) with several realistic alternatives and several criteria identified in expert seminars in Salta and Madrid, we have obtained hopeful results and more recently new modifications introduced have generated better results

Mulch materials in processing tomato: a multivariate approach.

Mulch materials of different origins have been introduced into the agricultural sector in recent years alternatively to the standard polyethylene due to its environmental impact. This study aimed to evaluate the multivariate response of mulch materials over three consecutive years in a processing tomato (Solanum lycopersicon L.) crop in Central Spain. Two biodegradable plastic mulches (BD1, BD2), one oxo-biodegradable material (OB), two types of paper (PP1, PP2), and one barley straw cover (BS) were compared using two control treatments (standard black polyethylene [PE] and manual weed control [MW]). A total of 17 variables relating to yield, fruit quality, and weed control were investigated. Several multivariate statistical techniques were applied, including principal component analysis, cluster analysis, and discriminant analysis. A group of mulch materials comprised of OB and BD2 was found to be comparable to black polyethylene regarding all the variables considered. The weed control variables were found to be an important source of discrimination. The two paper mulches tested did not share the same treatment group membership in any case: PP2 presented a multivariate response more similar to the biodegradable plastics, while PP1 was more similar to BS and MW. Based on our multivariate approach, the materials OB and BD2 can be used as an effective, more environmentally friendly alternative to polyethylene mulches

Multiscaling properties on sequences of turbulent plumes images

A multifractal analysis on a finite-range-scale of the plume concentration images at different experimental conditions (the height of the source Ho), where the measure is the grey value of the image (from 0 to 255), was applied to study its structure through time. The multifractal spectrum showed the characteristic inverse U-shape and a similar evolution in all Ho. The variation of the Hölder exponent (¿a) presented different amplitudes at different moments and increased with time. The symmetry of the spectrum (¿f) decreased with time achieving negative values (from left hand asymmetry evolving to right asymmetry). We show the different behaviour of axial velocity (W) with ¿a and ¿f. There is a linear relation of entrainment coefficient (ae) and the entropy dimension (a1). Therefore, the multifractal spectrum and the derived parameters can be used as markers of plume evolution as well as to study the effect of experimental conditions.Postprint (published version

Comparison of fractal dimensions based on segmented NDVI fields obtained from different remote sensors.

Satellite image data have become an important source of information for monitoring vegetation and mapping land cover at several scales. Beside this, the distribution and phenology of vegetation is largely associated with climate, terrain characteristics and human activity. Various vegetation indices have been developed for qualitative and quantitative assessment of vegetation using remote spectral measurements. In particular, sensors with spectral bands in the red (RED) and near-infrared (NIR) lend themselves well to vegetation monitoring and based on them [(NIR - RED) / (NIR + RED)] Normalized Difference Vegetation Index (NDVI) has been widespread used. Given that the characteristics of spectral bands in RED and NIR vary distinctly from sensor to sensor, NDVI values based on data from different instruments will not be directly comparable. The spatial resolution also varies significantly between sensors, as well as within a given scene in the case of wide-angle and oblique sensors. As a result, NDVI values will vary according to combinations of the heterogeneity and scale of terrestrial surfaces and pixel footprint sizes. Therefore, the question arises as to the impact of differences in spectral and spatial resolutions on vegetation indices like the NDVI. The aim of this study is to establish a comparison between two different sensors in their NDVI values at different spatial resolutions