Graphic cryptography with pseudorandom bit generators and cellular automata

In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored image defined by pixels and by any number of colors. This cryptosystem is based on a reversible bidimensional cellular automaton and uses a pseudorandom bit generator. As the key of the cryptosystem is the seed of the pseudorandom bit generator, the latter has to be cryptographically secure. Moreover, the recovered image from the ciphered image has not loss of resolution and the ratio between the ciphered image and the original one, i.e., the factor expansion of the cryptosystem, is $1$.Peer reviewe

Graphic cryptosystem using memory cellular automata

In this paper, a new graphic cryptosystem based on reversible memory cellular automata is introduced. Its main feature is that the original image and the cipher image are defined by the same palette of colors and that the recovered image is equal to the original one, that is, there is not loss of resolution. Moreover, it is proved that the proposed cryptosystem is secure against brute-force attacks, statistical attacks and chosen plaintext attacksPeer reviewe

Land use modelling and the role of stakeholders in natural protected areas: the case of Doñana national park, Spain

Doñana, a National Park since 1969, a UNESCO site since 1994 among other protected area designations of national and international character, is a coastal dune and marshland ecosystem of outstanding importance for biodiversity and conservation at the mouth of the Guadalaquivir River, Southwest Spain. However, the Doñana natural area is seriously threatened by global change factors such as humanly induced climate change, habitat loss, overexploitation of ecosystem services, and pollution. Not all stakeholders are convinced of the benefits of the national park, and management of Doñana, its environs and watershed are the subject of intense disagreement. This interplay between natural characteristics of great value with intense human pressure makes Doñana a fascinating workshop for the study of global human environment interactions. Here, we discuss the role of stakeholders in the application of a cellular automatabased model to Doñana and its environs and present the results of a series of exercises undertaken with stakeholders to parametrize the model, something often done by researchers without stakeholder engagement. By engaging with stakeholders early in the project, feedback generated from workshops contributes to model development. Stakeholders are therefore contributors of empirical data for the model as well as independent evaluators providing local and specialist knowledge

Evaluación de datos interpolados para la detección de índices de extremos térmicos

Ponencia presentada en: VIII Congreso de la Asociación Española de Climatología celebrado en Salamanca entre el 25 y el 28 de septiembre de 2012.[ES]En este trabajo realizamos una comparación de índices climáticos extremos observados e interpolados. En las investigaciones sobre las consecuencias del cambio climático en eventos extremos, se utilizan simulaciones de los índices de extremos que se obtienen en una malla regular. Para evaluar las simulaciones es preciso interpolar los datos observados a la correspondiente malla regular. Uno de los problemas que plantea la interpolación es el efecto de suavizamiento, ya que produce atenuación de las variaciones y puede dar lugar a pérdida de identificación de los eventos extremos. Por lo tanto, es interesante desarrollar este estudio para comprobar la utilidad de los datos interpolados en estudios de impacto.[EN]In this study we perform a comparison of extreme indices from observed and interpolated dataset. In evaluation studies on simulated data is required to have grid datasets. However, observed data are irregularly distributed and the interpolation procedure may cause some smoothing on datasets mainly in the extreme indices. Therefore, it is interesting to learn about the effect of interpolation on extreme indices to assess their applicability for impact studies. Spatial and temporal analyses were applied to daily maximum and minimum temperatures and also to the derived extremes, summer and frost days.Agradecemos las subvenciones de los proyectos CGL2011-23209 del Ministerio de Economía y Competitividad y SA222A11-2 de la Junta de Castilla y León

Manufacturing processes in the textile industry. Expert Systems for fabrics production

 The textile industry is characterized by the economic activity whose objective is the production of fibres, yarns, fabrics, clothing and textile goods for home and decoration, as well as technical and industrial purposes. Within manufacturing, the Textile is one of the oldest and most complex sectors which includes a large number of sub-sectors covering the entire production cycle, from raw materials and intermediate products, to the production of final products. Textile industry activities present different subdivisions,each with its own traits. The length of the textile process and the variety of its technicalprocesses lead to the coexistence of different sub-sectors in regards to their business structure and integration. The textile industry is developing expert systems applicationsto increase production, improve quality and reduce costs. The analysis of textile designs or structures includes the use of mathematical models to simulate the behavior of the textile structures (yarns, fabrics and knitting). The Finite Element Method (FEM) has largely facilitated the prediction of the behavior of that textile structure under mechanical loads. For classification problems Artificial Neural Networks (ANNs) have proved to be a very effective tool as a quick and accurate solution. The Case-Based Reasoning (CBR) method proposed in this study complements the results of the finite element simulation, mathematical modeling and neural networks methods

Efficient high-order finite difference methods for nonlinear Klein–Gordon equations. I: Variants of the phi-four model and the form-I of the nonlinear Klein–Gordon equation

In this paper, the problem of solving some nonlinear Klein–Gordon equations (KGEs) is considered. Here, we derive different fourth- and sixth-order explicit and implicit algorithms to solve the phi-four equation and the form-I of the nonlinear Klein–Gordon equation. Stability and consistency of the proposed schemes are studied under certain conditions. Numerical results are presented and then compared with others obtained from some methods already existing in the scientific literature to explain the efficiency of the new algorithms. It is also shown that similar schemes can be proposed to solve many classes of nonlinear KGEs

Control de calidad de datos diarios en la Península Ibérica

Ponencia presentada en: VI Congreso Internacional de la Asociación Española de Climatología celebrado en Tarragona del 8 al 11 de octubre de 2008.[ES]La calidad de los datos es un requisito necesario en estudios de variabilidad climática, principalmente cuando se analizan datos de gran resolución espacial y temporal. Para analizar los extremos climáticos es preciso utilizar datos diarios, pero estas series temporales evidencian algunos errores debidos a discontinuidades y otros al azar; por ejemplo, que la precipitación sea menor que cero y que la temperatura máxima sea menor que la mínima para un día determinado. El procedimiento para corregir estos errores resulta muy complicado y hemos adoptado los métodos desarrollados en http://cccma.seos.uvic.ca/ETCCDMI /software.shtml, programados en lenguajes R (RClimDex y RHTest) y Fortran (FClimDex y FHTest). Mostraremos algunos ejemplos aplicados a datos observados “in situ” y compararemos la calidad de estos datos frente a la de los datos de reanálisis del NCEP/NCAR.[EN]Data quality has to be considered in studies about climate variability, especially when data have high spatial and temporal resolutions. The extreme climate research requires daily data which very often have errors due to discontinuities and other random causes, for example, we found some negative precipitation values, and maximum temperature lower than minimum. Therefore, we need to adjust the data to correct these errors. The methods to obtain homogeneous data are complicated. We have addressed the procedure developed in http://cccma.seos.uvic.ca/ETCCDMI/software.shtml, that provides software in R (RClimDex and RHTest) and Fortran (FClimDex and FHTest) languages. In this paper we present some examples about the adjustment technique applied to observed data “in situ” and we compare the quality of the observed against the NCEP/NCAR reanalysis data.Este trabajo ha sido financiado con los proyectos de investigación MEC-CGL2005-06600-CO-01/CLI, de la Junta de Castilla y León SA039/A05, cofinanciados con fondos europeos y con el proyecto de ayudas a la investigación “Memoria D. Samuel Solórzano Barruso” de 2008

Influencia de índices de circulación en las variaciones de precipitación invernal de la Península Ibérica

Ponencia presentada en: I Congreso de la Asociación Española de Climatología “La climatología española en los albores del siglo XXI”, celebrado en Barcelona del 1 al 3 de diciembre de 1999.[ES]Se analizan las variaciones interanuales de la precipitación invernal utilizando observaciones de la península Ibérica y se relacionan con índices teleconectivos. Las principales conclusiones son: precipitaciones más bajas durante la fase positiva de la Oscilación del Atlántico Norte y del patrón del este del Atlántico/Oeste de Rusia; el fenómeno El Niño produce precipitaciones inferiores a lo normal hacia la vertiente Mediterránea para el invierno.[EN]A description of precipitation interannual variations and the response to the teleconnection atmospheric and oceanic indices are analyzed for winter precipitation observations over the Iberian Peninsula. The main findings are: below precipitation is produced during positive phase of the North Atlantic Oscillation and the East Atlantic West Russian patterns; the El Niño event produces below precipitation than normal in winter toward Mediterranean area.Esta investigación está subvencionada con los proyectos: CICYT96-1871-CO-04 y SA57/99

Numerical schemes for general Klein–Gordon equations with Dirichlet and nonlocal boundary conditions

In this work, we address the problem of solving nonlinear general Klein–Gordon equations (nlKGEs). Different fourth- and sixth-order, stable explicit and implicit, finite difference schemes are derived. These new methods can be considered to approximate all type of Klein–Gordon equations (KGEs) including phi-four, forms I, II, and III, sine-Gordon, Liouville, damped Klein–Gordon equations, and many others. These KGEs have a great importance in engineering and theoretical physics.The higher-order methods proposed in this study allow a reduction in the number of nodes, which might also be very interesting when solving multi-dimensional KGEs. We have studied the stability and consistency of the proposed schemes when considering certain smoothness conditions of the solutions. Additionally, both the typical Dirichlet and some nonlocal integral boundary conditions have been studied. Finally, some numerical results are provided to support the theoretical aspects previously considered

Impacto de índices climáticos en las variaciones de precipitación acumulada en los meses febrero, marzo y abril

Ponencia presentada en: III Congreso de la Asociación Española de Climatología “El agua y el clima”, celebrado en Palma de Mallorca del 16 al 19 de junio de 2002.[ES]Hemos analizado las series de precipitación acumulada en el comienzo de la primavera (febrero, marzo y abril) de la Península Ibérica porque hemos identificado una tendencia de disminución en febrero y marzo, siendo más destacada hacia el sur de la península. La variabilidad de la precipitación fue caracterizada mediante el método de análisis de componentes principales. Las series temporales asociadas a los modos de variación se relacionaron con índices climáticos de circulación (teleconexión) y de temperaturas del mar como El Nino y la temperatura en zonas tropicales. Hemos obtenido que la disminución de la precipitación se corresponde con una tendencia de aumento de los índices oscilación del Ártico, El Niño y la temperatura del mar en la región tropical (10S- 10N).[EN]The accumulated precipitation in February, March and April over the Iberian peninsula has been analysed because a decreasing trend was identified in February and March, it is higher towards southern part of the peninsula. The precipitation variations were characterized by means of principal component analysis and the associated time series were related to teleconexion and sea surface temperature (SST) indices like El Niño and SST over global tropical regions (10S-10N). There is a correspondence between the decreasing precipitation and the increasing of the Arctic oscillation, El Niño and the tropical SST