Argon ratios, 40Ar/39Ar datings and biostratigraphic ages of ODP Leg 165 sites

Drilling in the Caribbean Sea during Ocean Drilling Program Leg 165 has recovered a large number of silicic tephra layers and led to the discovery of three major episodes of explosive volcanism that occurred during the last 55 m.y. on the margins of this evolving ocean basin. The earliest episode is marked by Paleocene to early Eocene explosive volcanism on the Cayman Rise, associated with activity of the Cayman arc, an island arc that was the westward extension of the Sierra Maestra volcanic arc in southern Cuba. Caribbean sediments also document a major mid- to late Eocene explosive volcanic episode that is attributed to ignimbrite-forming eruptions on the Chortis Block in Central America to the west. This event is contemporaneous with the first phase of activity of the Sierra Madre volcanic episode in Mexico, the largest ignimbrite province on Earth. In the Caribbean sediments, a Miocene episode of explosive volcanism is comparable to the Eocene event, and also attributed to sources in the Central American arc to the west. Radiometric 40Ar/39Ar dates have been obtained for biotites and sanidines from 27 tephra layers, providing absolute ages for the volcanic episodes and further constraining the geochronology of Caribbean sediments. Volcanic activity of the Cayman arc is attributed to the northward subduction of the leading edge of the oceanic plate that carried the Caribbean oceanic plateau. Although the factors generating the large episodes of Central American explosive volcanism are unclear, we propose that they are related to contemporary major readjustments of plate tectonic configuration in the Pacific.

Interface de recuperación para catálogos en línea con salidas ordenadas por probable relevancia

Se presenta el desarrollo de una interface de recuperación de información para catálogos en línea de acceso público (plataforma CDS/ISIS), basada en el concepto de similaridad para generar los resultados de una búsqueda ordenados por posible relevancia. Se expresan los fundamentos teóricos involucrados, para luego detallar la forma en que se efectuó su aplicación tecnológica, explícita a nivel de programación. Para finalizar se esbozan los problemas de implementación según el entorno

Interface de recuperación para catálogos en línea con salidas ordenadas por probable relevancia

Se presenta el desarrollo de una interface de recuperación de información para catálogos en línea de acceso público (plataforma CDS/ISIS), basada en el concepto de similaridad para generar los resultados de una búsqueda ordenados por posible relevancia. Se expresan los fundamentos teóricos involucrados, para luego detallar la forma en que se efectuó su aplicación tecnológica, explícita a nivel de programación. Para finalizar se esbozan los problemas de implementación según el entorno

Magnetic susceptibility and electric conductivity of marine surficial sediments by benthic electromagnetic profiling

Distribution, accumulation and diagenesis of surficial sediments in coastal and continental shelf systems follow complex chains of localized processes and form deposits of great spatial variability. Given the environmental and economic relevance of ocean margins, there is growing need for innovative geophysical exploration methods to characterize seafloor sediments by more than acoustic properties. A newly conceptualized benthic profiling and data processing approach based on controlled source electromagnetic (CSEM) imaging permits to coevally quantify the magnetic susceptibility and the electric conductivity of shallow marine deposits. The two physical properties differ fundamentally insofar as magnetic susceptibility mostly assesses solid particle characteristics such as terrigenous or iron mineral content, redox state and contamination level, while electric conductivity primarily relates to the fluid-filled pore space and detects salinity, porosity and grain-size variations. We develop and validate a layered half-space inversion algorithm for submarine multifrequency CSEM with concentric sensor configuration. Guided by results of modeling, we modified a commercial land CSEM sensor for submarine application, which was mounted into a nonconductive and nonmagnetic bottom-towed sled. This benthic EM profiler Neridis II achieves 25 soundings/second at 3-4 knots over continuous profiles of up to hundred kilometers. Magnetic susceptibility is determined from the 75 Hz in-phase response (90% signal originates from the top 50 cm), while electric conductivity is derived from the 5 kHz out-of-phase (quadrature) component (90% signal from the top 92 cm). Exemplary survey data from the north-west Iberian margin underline the excellent sensitivity, functionality and robustness of the system in littoral (~0-50 m) and neritic (~50-300 m) environments. Susceptibility vs. porosity cross-plots successfully identify known lithofacies units and their transitions. All presently available data indicate an eminent potential of CSEM profiling for assessing the complex distribution of shallow marine surficial sediments and for revealing climatic, hydrodynamic, diagenetic and anthropogenic factors governing their formation.

New methods for the estimation of Takagi-Sugeno model based extended Kalman filter and its applications to optimal control for nonlinear systems

This paper describes new approaches to improve the local and global approximation (matching) and modeling capability of Takagi–Sugeno (T-S) fuzzy model. The main aim is obtaining high function approximation accuracy and fast convergence. The main problem encountered is that T-S identification method cannot be applied when the membership functions are overlapped by pairs. This restricts the application of the T-S method because this type of membership function has been widely used during the last 2 decades in the stability, controller design of fuzzy systems and is popular in industrial control applications. The approach developed here can be considered as a generalized version of T-S identification method with optimized performance in approximating nonlinear functions. We propose a noniterative method through weighting of parameters approach and an iterative algorithm by applying the extended Kalman filter, based on the same idea of parameters’ weighting. We show that the Kalman filter is an effective tool in the identification of T-S fuzzy model. A fuzzy controller based linear quadratic regulator is proposed in order to show the effectiveness of the estimation method developed here in control applications. An illustrative example of an inverted pendulum is chosen to evaluate the robustness and remarkable performance of the proposed method locally and globally in comparison with the original T-S model. Simulation results indicate the potential, simplicity, and generality of the algorithm. An illustrative example is chosen to evaluate the robustness. In this paper, we prove that these algorithms converge very fast, thereby making them very practical to use.

MIRACLE’s Hybrid Approach to Bilingual and Monolingual Information Retrieval

The main goal of the bilingual and monolingual participation of the MIRACLE team in CLEF 2004 was to test the effect of combination approaches on information retrieval. The starting point was a set of basic components: stemming, transformation, filtering, generation of n-grams, weighting and relevance feedback. Some of these basic components were used in different combinations and order of application for document indexing and for query processing. A second order combination was also tested, mainly by averaging or selective combination of the documents retrieved by different approaches for a particular query.

Uniformly reweighted belief propagation for distributed Bayesian hypothesis testing

Belief propagation (BP) is a technique for distributed inference in wireless networks and is often used even when the underlying graphical model contains cycles. In this paper, we propose a uniformly reweighted BP scheme that reduces the impact of cycles by weighting messages by a constant ?edge appearance probability? rho ? 1. We apply this algorithm to distributed binary hypothesis testing problems (e.g., distributed detection) in wireless networks with Markov random field models. We demonstrate that in the considered setting the proposed method outperforms standard BP, while maintaining similar complexity. We then show that the optimal ? can be approximated as a simple function of the average node degree, and can hence be computed in a distributed fashion through a consensus algorithm.

NDT for concrete under accelerated freeze/thaw tests and surface scaling

Freezing of water or salt solution in concrete pores is a main cause for severe damage and significant reduction of the service life. Most of the freeze-thaw (F-T) accelerated tests measure the scaling of concrete by weighting. This paper presents complementary procedures based on the use of strain gages and ultrasonic pulse velocity (UPV) for measuring the deterioration of concrete due to freezing and thawing. These non-destructive testing (NDT) procedures are applied to two types of concretes, one susceptible to F-T damage and the other does not. The results show a good correlation between scaling and the measurements obtained with NDT. Showing NDT the advantage to detect before the damage and to perform continuous measurement

B-LOG: A branch and bound methodology for the parallel execution of logic programs

We propose a computational methodology -"B-LOG"-, which offers the potential for an effective implementation of Logic Programming in a parallel computer. We also propose a weighting scheme to guide the search process through the graph and we apply the concepts of parallel "branch and bound" algorithms in order to perform a "best-first" search using an information theoretic bound. The concept of "session" is used to speed up the search process in a succession of similar queries. Within a session, we strongly modify the bounds in a local database, while bounds kept in a global database are weakly modified to provide a better initial condition for other sessions. We also propose an implementation scheme based on a database machine using "semantic paging", and the "B-LOG processor" based on a scoreboard driven controller.

Diseño de un modelo de riesgo integral de incendios forestales mediante técnicas multicriterio y su automatización en sistemas de información geográfica : una aplicación en la Comunidad Valenciana

Los incendios forestales son la principal causa de mortalidad de árboles en la Europa mediterránea y constituyen la amenaza más seria para los ecosistemas forestales españoles. En la Comunidad Valenciana, diariamente se despliega cerca de un centenar de vehículos de vigilancia, cuya distribución se apoya, fundamentalmente, en un índice de riesgo de incendios calculado en función de las condiciones meteorológicas. La tesis se centra en el diseño y validación de un nuevo índice de riesgo integrado de incendios, especialmente adaptado a la región mediterránea y que facilite el proceso de toma de decisiones en la distribución diaria de los medios de vigilancia contra incendios forestales. El índice adopta el enfoque de riesgo integrado introducido en la última década y que incluye dos componentes de riesgo: el peligro de ignición y la vulnerabilidad. El primero representa la probabilidad de que se inicie un fuego y el peligro potencial para que se propague, mientras que la vulnerabilidad tiene en cuenta las características del territorio y los efectos potenciales del fuego sobre el mismo. Para el cálculo del peligro potencial se han identificado indicadores relativos a los agentes naturales y humanos causantes de incendios, la ocurrencia histórica y el estado de los combustibles, extremo muy relacionado con la meteorología y las especies. En cuanto a la vulnerabilidad se han empleado indicadores representativos de los efectos potenciales del incendio (comportamiento del fuego, infraestructuras de defensa), como de las características del terreno (valor, capacidad de regeneración…). Todos estos indicadores constituyen una estructura jerárquica en la que, siguiendo las recomendaciones de la Comisión europea para índices de riesgo de incendios, se han incluido indicadores representativos del riesgo a corto plazo y a largo plazo. El cálculo del valor final del índice se ha llevado a cabo mediante la progresiva agregación de los componentes que forman cada uno de los niveles de la estructura jerárquica del índice y su integración final. Puesto que las técnicas de decisión multicriterio están especialmente orientadas a tratar con problemas basados en estructuras jerárquicas, se ha aplicado el método TOPSIS para obtener la integración final del modelo. Se ha introducido en el modelo la opinión de los expertos, mediante la ponderación de cada uno de los componentes del índice. Se ha utilizado el método AHP, para obtener las ponderaciones de cada experto y su integración en un único peso por cada indicador. Para la validación del índice se han empleado los modelos de Ecuaciones de Estimación Generalizadas, que tienen en cuenta posibles respuestas correlacionadas. Para llevarla a cabo se emplearon los datos de oficiales de incendios ocurridos durante el período 1994 al 2003, referenciados a una cuadrícula de 10x10 km empleando la ocurrencia de incendios y su superficie, como variables dependientes. Los resultados de la validación muestran un buen funcionamiento del subíndice de peligro de ocurrencia con un alto grado de correlación entre el subíndice y la ocurrencia, un buen ajuste del modelo logístico y un buen poder discriminante. Por su parte, el subíndice de vulnerabilidad no ha presentado una correlación significativa entre sus valores y la superficie de los incendios, lo que no descarta su validez, ya que algunos de sus componentes tienen un carácter subjetivo, independiente de la superficie incendiada. En general el índice presenta un buen funcionamiento para la distribución de los medios de vigilancia en función del peligro de inicio. No obstante, se identifican y discuten nuevas líneas de investigación que podrían conducir a una mejora del ajuste global del índice. En concreto se plantea la necesidad de estudiar más profundamente la aparente correlación que existe en la provincia de Valencia entre la superficie forestal que ocupa cada cuadrícula de 10 km del territorio y su riesgo de incendios y que parece que a menor superficie forestal, mayor riesgo de incendio. Otros aspectos a investigar son la sensibilidad de los pesos de cada componente o la introducción de factores relativos a los medios potenciales de extinción en el subíndice de vulnerabilidad. Summary Forest fires are the main cause of tree mortality in Mediterranean Europe and the most serious threat to the Spanisf forest. In the Spanish autonomous region of Valencia, forest administration deploys a mobile fleet of 100 surveillance vehicles in forest land whose allocation is based on meteorological index of wildlandfire risk. This thesis is focused on the design and validation of a new Integrated Wildland Fire Risk Index proposed to efficient allocation of vehicles and specially adapted to the Mediterranean conditions. Following the approaches of integrated risk developed last decade, the index includes two risk components: Wildland Fire Danger and Vulnerability. The former represents the probability a fire ignites and the potential hazard of fire propagation or spread danger, while vulnerability accounts for characteristics of the land and potential effects of fire. To calculate the Wildland Fire Danger, indicators of ignition and spread danger have been identified, including human and natural occurrence agents, fuel conditions, historical occurrence and spread rate. Regarding vulnerability se han empleado indicadores representativos de los efectos potenciales del incendio (comportamiento del fuego, infraestructurasd de defensa), como de las características del terreno (valor, capacidad de regeneración…). These indicators make up the hierarchical structure for the index, which, following the criteria of the European Commission both short and long-term indicators have been included. Integration consists of the progressive aggregation of the components that make up every level in risk the index and, after that, the integration of these levels to obtain a unique value for the index. As Munticriteria methods are oriented to deal with hierarchically structured problems and with situations in which conflicting goals prevail, TOPSIS method is used in the integration of components. Multicriteria methods were also used to incorporate expert opinion in weighting of indicators and to carry out the aggregation process into the final index. The Analytic Hierarchy Process method was used to aggregate experts' opinions on each component into a single value. Generalized Estimation Equations, which account for possible correlated responses, were used to validate the index. Historical records of daily occurrence for the period from 1994 to 2003, referred to a 10x10-km-grid cell, as well as the extent of the fires were the dependant variables. The results of validation showed good Wildland Fire Danger component performance, with high correlation degree between Danger and occurrence, a good fit of the logistic model used and a good discrimination power. The vulnerability component has not showed a significant correlation between their values and surface fires, which does not mean the index is not valid, because of the subjective character of some of its components, independent of the surface of the fires. Overall, the index could be used to optimize the preventing resources allocation. Nevertheless, new researching lines are identified and discussed to improve the overall performance of the index. More specifically the need of study the inverse relationship between the value of the wildfire Fire Danger component and the forested surface of each 10 - km cell is set out. Other points to be researched are the sensitivity of the index component´s weight and the possibility of taking into account indicators related to fire fighting resources to make up the vulnerability component.

An efficient ‘a priori’ model reduction for boundary element models

The Boundary Element Method (BEM) is a discretisation technique for solving partial differential equations, which offers, for certain problems, important advantages over domain techniques. Despite the high CPU time reduction that can be achieved, some 3D problems remain today untreatable because the extremely large number of degrees of freedom—dof—involved in the boundary description. Model reduction seems to be an appealing choice for both, accurate and efficient numerical simulations. However, in the BEM the reduction in the number of degrees of freedom does not imply a significant reduction in the CPU time, because in this technique the more important part of the computing time is spent in the construction of the discrete system of equations. In this way, a reduction also in the number of weighting functions, seems to be a key point to render efficient boundary element simulations.

Text categorization methods for automatic estimation of verbal intelligence

In this paper we investigate whether conventional text categorization methods may suffice to infer different verbal intelligence levels. This research goal relies on the hypothesis that the vocabulary that speakers make use of reflects their verbal intelligence levels. Automatic verbal intelligence estimation of users in a spoken language dialog system may be useful when defining an optimal dialog strategy by improving its adaptation capabilities. The work is based on a corpus containing descriptions (i.e. monologs) of a short film by test persons yielding different educational backgrounds and the verbal intelligence scores of the speakers. First, a one-way analysis of variance was performed to compare the monologs with the film transcription and to demonstrate that there are differences in the vocabulary used by the test persons yielding different verbal intelligence levels. Then, for the classification task, the monologs were represented as feature vectors using the classical TF–IDF weighting scheme. The Naive Bayes, k-nearest neighbors and Rocchio classifiers were tested. In this paper we describe and compare these classification approaches, define the optimal classification parameters and discuss the classification results obtained.

A new approach to fuzzy estimation of Takagi-Sugeno model and its applications to optimal control for nonlinear systems

An efficient approach is presented to improve the local and global approximation and modelling capability of Takagi-Sugeno (T-S) fuzzy model. The main aim is obtaining high function approximation accuracy. The main problem is that T-S identification method cannot be applied when the membership functions are overlapped by pairs. This restricts the use of the T-S method because this type of membership function has been widely used during the last two decades in the stability, controller design and are popular in industrial control applications. The approach developed here can be considered as a generalized version of T-S method with optimized performance in approximating nonlinear functions. A simple approach with few computational effort, based on the well known parameters' weighting method is suggested for tuning T-S parameters to improve the choice of the performance index and minimize it. A global fuzzy controller (FC) based Linear Quadratic Regulator (LQR) is proposed in order to show the effectiveness of the estimation method developed here in control applications. Illustrative examples of an inverted pendulum and Van der Pol system are chosen to evaluate the robustness and remarkable performance of the proposed method and the high accuracy obtained in approximating nonlinear and unstable systems locally and globally in comparison with the original T-S model. Simulation results indicate the potential, simplicity and generality of the algorithm.

Atlas-free Brain Tissue Segmentation Using a Single T1-weighted MRI Acquisition

Many studies investigating the aging brain or disease-induced brain alterations rely on accurate and reproducible brain tissue segmentation. Being a preliminary processing step prior to the segmentation, reliableskull-stripping the removal ofnon-brain tissue is also crucial for all later image assessment. Typically, segmentation algorithms rely on an atlas i.e. pre-segmented template data. Brain morphology, however, differs considerably depending on age, sex and race. In addition, diseased brains may deviate significantly from the atlas information typically gained from healthy volunteers. The imposed prior atlas information can thus lead to degradation of segmentation results. The recently introduced MP2RAGE sequence provides a bias-free T1 contrast with heavily reduced T2*- and PD-weighting compared to the standard MP-RAGE [1]. To this end, it acquires two image volumes at different inversion times in one acquisition, combining them to a uniform, i.e. homogenous image. In this work, we exploit the advantageous contrast properties of the MP2RAGE and combine it with a Dixon (i.e. fat-water separation) approach. The information gained by the additional fat image of the head considerably improves the skull-stripping outcome [2]. In conjunction with the pure T1 contrast of the MP2RAGE uniform image, we achieve robust skull-stripping and brain tissue segmentation without the use of an atlas

User benefit assessment by a dynamic LUTI model for Madrid

Assessing users’ benefit in a transport policy implementation has been studied by many researchers using theoretical or empirical measures. However, few of them measure users’ benefit in a different way from the consumer surplus. Therefore, this paper aims to assess a new measure of user benefits by weighting consumer surplus in order to include equity assessment for different transport policies simulated in a dynamic middle-term LUTI model adapted to the case study of Madrid. Three different transport policies, including road pricing, parking charge and public transport improvement have been simulated through the Metropolitan Activity Relocation Simulator, MARS, the LUTI calibrated model for Madrid). A social welfare function (WF) is defined using a cost benefit analysis function that includes mainly costs and benefits of users and operators of the transport system. Particularly, the part of welfare function concerning the users, (i.e. consumer surplus), is modified by a compensating weight (CW) which represents the inverse of household income level. Based on the modified social welfare function, the effects on the measure of users benefits are estimated and compared with the old WF ́s results as well. The result of the analysis shows that road pricing leads a negative effect on the users benefits specially on the low income users. Actually, the road pricing and parking charge implementation results like a regressive policy especially at long term. Public transport improvement scenario brings more positive effects on low income user benefits. The integrated (road pricing and increasing public services) policy scenario is the one which receive the most user benefits. The results of this research could be a key issue to understanding the relationship between transport systems policies and user benefits distribution in a metropolitan context.