A comparative study of methods for automatic compile-time parallelization of logic programs

This paper presents a study of the effectiveness of three different algorithms for the parallelization of logic programs based on compile-time detection of independence among goals. The algorithms are embedded in a complete parallelizing compiler, which incorporates different abstract interpretation-based program analyses. The complete system shows the task of automatic program parallelization to be practical. The trade-offs involved in using each of the algorithms in this task are studied experimentally, weaknesses of these identified, and possible improvements discussed.

Automatic Understanding of ATC Speech: Study of Prospectives and Field Experiments for Several Controller Positions

Although there has been a lot of interest in recognizing and understanding air traffic control (ATC) speech, none of the published works have obtained detailed field data results. We have developed a system able to identify the language spoken and recognize and understand sentences in both Spanish and English. We also present field results for several in-tower controller positions. To the best of our knowledge, this is the first time that field ATC speech (not simulated) is captured, processed, and analyzed. The use of stochastic grammars allows variations in the standard phraseology that appear in field data. The robust understanding algorithm developed has 95% concept accuracy from ATC text input. It also allows changes in the presentation order of the concepts and the correction of errors created by the speech recognition engine improving it by 17% and 25%, respectively, absolute in the percentage of fully correctly understood sentences for English and Spanish in relation to the percentages of fully correctly recognized sentences. The analysis of errors due to the spontaneity of the speech and its comparison to read speech is also carried out. A 96% word accuracy for read speech is reduced to 86% word accuracy for field ATC data for Spanish for the "clearances" task confirming that field data is needed to estimate the performance of a system. A literature review and a critical discussion on the possibilities of speech recognition and understanding technology applied to ATC speech are also given.

Riparian woodland encroachment following flow regulation: a comparative study of Boreal and Mediterranean streams

Water development accompanying mankind development has turned rivers into endangered ecosystems. Improving the understanding of ecological responses to river management actions is a key issue for assuring sustainable water management. However, few studies have been published where ecological metrics have been quantified in response to various degrees of flow alteration. In this work, changes in natural distribution of trees and shrubs within the riparian corridor (as indicator of the ecological status of the fluvial ecosystem) were quantified at multiple sites along a flow alteration gradient (as indicator of impact) along two regulated river reaches, one Boreal and the other Mediterranean, each downstream of a dam. Based on the obtained relationships we evaluated differences in response trends related to local physico-climatic factors of the two biomes and regarding to differing life-forms. Woody vegetation establishment patterns represented objective indicators of ecological responses to flow alteration. We found different responses between life-forms. Both trees and shrubs migrated downwards to the channel after dam closure, but shrubs were most impacted under higher degrees of flow alteration in terms of lateral movement. In addition, our results show clear longitudinal recovery trends of natural patterns of tree and shrub distribution corresponding to a decrease in intensity of hydrologic alteration in the Boreal river. However, vegetation encroachment persisted along the entire Mediterranean study reach. This may result from a relatively low gradient of decrease of hydrologic alteration with distance from the dam, coupled with other overlapping pressures and the mediating effect of physico-climatic characteristics on vegetation responses.

A simulation study of or- and independent and-parallelism

Although studies of a number of parallel implementations of logic programming languages are now available, the results are difficult to interpret due to the multiplicity of factors involved, the effect of each of which is difficult to sepárate. In this paper we present the results of a highlevel simulation study of or- and independent and-parallelism with a wide selection of Prolog programs that aims to facilítate this separation. We hope this study will be instrumental in better understanding and comparing results from actual implementations, as shown by an example in the paper. In addition, the paper examines some of the issues and tradeoffs associated with the combination of and- and or-parallelism and proposes reasonable solutions based on the simulation data.

Study of Impact and Compression Damage on Asian Pears

Result of impact and compression tests on Chojuro, Twentieth Century, Tsu Li, and Ya Li varieties of Asian pears indicate that Chojuro pears are the firmest and most resistant to mechanical damage. At the time of harvest, Tsu Li and Ya Li pears could resist mechanical damage nearly as well as Chojuro pears, but they become more susceptible to bruising in cold storage. Twentieth Century pears are most sensitive to impact and compression bruising. Increased time in the ripening room produces more softening and increased bruise resistance of Chojuro and Twentieth Century pears than of Tsu Li and Ya Li pears.

A comparative study of SISO and MIMO control strategies for floor vibration damping

Civil engineering structures such as floor systems with open-plan layout or lightweight footbridges are susceptible to excessive level of vibrations caused by human loading. Active vibration control (AVC) via inertial mass actuators has been shown to be a viable technique to mitigate vibrations, allowing structures to satisfy vibration serviceability limits. Most of the AVC applications involve the use of SISO (single input single-output) strategies based on collocated control. However, in the case of floor structures, in which mostof the vibration modes are locally spatially distributed, SISO or multi-SISO strategies are quite inefficient. In this paper, a MIMO (multi-inputs multi-outputs) control in decentralised and centralised configuration is designed. The design process simultaneously finds the placement of multiple actuators and sensors and the output feedback gains. Additionally, actuator dynamics, actuator nonlinearities and frequency and time weightings are considered into the design process. Results with SISO and decentralised and centralised MIMO control (for a given number of actuators and sensors) are compared, showing the advantages of MIMO control for floor vibration control.

Learning Analytics and Interactions in Virtual Learning Environments. A Comparative Study of Typologies and their Relationship with Academic Performance

Analysis of learning data (learning analytics) is a new research field with high growth potential. The main objective of Learning analytics is the analysis of data (interactions being the basic data unit) generated in virtual learning environments, in order to maximize the outcomes of the learning process; however, a consensus has not been reached yet on which interactions must be measured and what is their influence on learning outcomes. This research is grounded on the study of e-learning interaction typologies and their relationship with students? academic performance, by means of a comparative study between different interaction typologies (based on the agents involved, frequency of use and participation mode). The main conclusions are a) that classifications based on agents offer a better explanation of academic performance; and b) that each of the three typologies are able to explain academic performance in terms of some of their components (student-teacher and student-student interactions, evaluating students interactions and active interactions, respectively), with the other components being nonrelevant.

Estudio teórico de propiedades termodinámicas y optoelectronicas de nuevos materiales fotovoltaicos de banda intermedia = Theoretical study of thermodynamic and optoelectronic properties of new intermediate band photovoltaic materials

Los materiales de banda intermedia han atraido la atención de la comunidad científica en el campo de la energía solar fotovoltaica en los últimos años. Sin embargo, con el objetivo de entender los fundamentos de las células solares de banda intermedia, se debe llevar a cabo un estudio profundo de la características de los materiales. Esto se puede hacer mediante un modelo teórico usando Primeros Principios. A partir de este enfoque se pueden obtener resultados tales como la estructura electrónica y propiedades ópticas, entre otras, de los semiconductores fuertemente dopados y sus precursores. Con el fin de desentrañar las estructuras de estos sistemas electrónicos, esta tesis presenta un estudio termodinámico y optoelectrónico de varios materiales fotovoltaicos. Específicamente se caracterizaron los materiales avanzados de banda intermedia y sus precursores. El estudio se hizo en términos de caracterización teórica de la estructura electrónica, la energética del sistema, entre otros. Además la estabilidad se obtuvo usando configuraciones adaptadas a la simetría del sistema y basado en la combinatoria. Las configuraciones de los sitios ocupados por defectos permiten obtener información sobre un espacio de configuraciones donde las posiciones de los dopantes sustituidos se basan en la simetría del sólido cristalino. El resultado puede ser tratado usando elementos de termodinámica estadística y da información de la estabilidad de todo el espacio simétrico. Además se estudiaron otras características importantes de los semiconductores de base. En concreto, el análisis de las interacciones de van der Waals fueron incluidas en el semiconductor en capas SnS2, y el grado de inversión en el caso de las espinelas [M]In2S4. En este trabajo además realizamos una descripción teórica exhaustiva del sistema CdTe:Bi. Este material de banda-intermedia muestra características que son distintas a las de los otros materiales estudiados. También se analizó el Zn como agente modulador de la posición de las sub-bandas prohibidas en el material de banda-intermedia CuGaS2:Ti. Analizándose además la viabilidad termodinámica de la formación de este compuesto. Finalmente, también se describió el GaN:Cr como material de banda intermedia, en la estructura zinc-blenda y en wurtztite, usando configuraciones de sitios ocupados de acuerdo a la simetría del sistema cristalino del semiconductor de base. Todos los resultados, siempre que fue posible, fueron comparados con los resultados experimentales. ABSTRACT The intermediate-band materials have attracted the attention of the scientific community in the field of the photovoltaics in recent years. Nevertheless, in order to understand the intermediate-band solar cell fundamentals, a profound study of the characteristics of the materials is required. This can be done using theoretical modelling from first-principles. The electronic structure and optical properties of heavily doped semiconductors and their precursor semiconductors are, among others, results that can be obtained from this approach. In order to unravel the structures of these crystalline systems, this thesis presents a thermodynamic and optoelectronic study of several photovoltaic materials. Specifically advanced intermediate-band materials and their precursor semiconductors were characterized. The study was made in terms of theoretical characterization of the electronic structure, energetics among others. The stability was obtained using site-occupancy-disorder configurations adapted to the symmetry of the system and based on combinatorics. The site-occupancy-disorder method allows the formation of a configurational space of substitutional dopant positions based on the symmetry of the crystalline solid. The result, that can be treated using statistical thermodynamics, gives information of the stability of the whole space of symmetry of the crystalline lattice. Furthermore, certain other important characteristics of host semiconductors were studied. Specifically, the van der Waal interactions were included in the SnS2 layered semiconductor, and the inversion degree in cases of [M]In2S4 spinels. In this work we also carried out an exhaustive theoretical description of the CdTe:Bi system. This intermediate-band material shows characteristics that are distinct from those of the other studied intermediate-band materials. In addition, Zn was analysed as a modulator of the positions of the sub-band gaps in the CuGaS2:Ti intermediate-band material. The thermodynamic feasibility of the formation of this compound was also carried out. Finally GaN:Cr intermediate-band material was also described both in the zinc-blende and the wurtztite type structures, using the symmetry-adapted-space of configurations. All results, whenever possible, were compared with experimental results.

Numerical and experimental study of overtopping and failure of rockfill dams

This paper aims to present and validate a numerical technique for the simulation of the overtopping and onset of failure in rockfill dams due to mass sliding. This goal is achieved by coupling a fluid dynamic model for the simulation of the free surface and through-flow problems, with a numerical technique for the calculation of the rockfill response and deformation. Both the flow within the dam body and in its surroundings are taken into account. An extensive validation of the resulting computational method is performed by solving several failure problems on physical models of rockfill dams for which experimental results have been obtained by the authors.

Study of PM10 and PM2.5 levels in three European cities: Analysis of intra and inter urban variations

In the present paper, 1-year PM10 and PM 2.5 data from roadside and urban background monitoring stations in Athens (Greece), Madrid (Spain) and London (UK) are analysed in relation to other air pollutants (NO,NO2,NOx,CO,O3 and SO2)and several meteorological parameters (wind velocity, temperature, relative humidity, precipitation, solar radiation and atmospheric pressure), in order to investigate the sources and factors affecting particulate pollution in large European cities. Principal component and regression analyses are therefore used to quantify the contribution of both combustion and non-combustion sources to the PM10 and PM 2.5 levels observed. The analysis reveals that the EU legislated PM 10 and PM2.5 limit values are frequently breached, forming a potential public health hazard in the areas studied. The seasonal variability patterns of particulates varies among cities and sites, with Athens and Madrid presenting higher PM10 concentrations during the warm period and suggesting the larger relative contribution of secondary and natural particles during hot and dry days. It is estimated that the contribution of non-combustion sources varies substantially among cities, sites and seasons and ranges between 38-67% and 40-62% in London, 26-50% and 20-62% in Athens, and 31-58% and 33-68% in Madrid, for both PM10 and PM 2.5. Higher contributions from non-combustion sources are found at urban background sites in all three cities, whereas in the traffic sites the seasonal differences are smaller. In addition, the non-combustion fraction of both particle metrics is higher during the warm season at all sites. On the whole, the analysis provides evidence of the substantial impact of non-combustion sources on local air quality in all three cities. While vehicular exhaust emissions carry a large part of the risk posed on human health by particle exposure, it is most likely that mitigation measures designed for their reduction will have a major effect only at traffic sites and additional measures will be necessary for the control of background levels. However, efforts in mitigation strategies should always focus on optimal health effects.

Using the Cross-Entropy Method for Control Optimization: A Case Study of See-and-Avoid on Unmanned Aerial Vehicles

This paper presents an adaptation of the Cross-Entropy (CE) method to optimize fuzzy logic controllers. The CE is a recently developed optimization method based on a general Monte-Carlo approach to combinatorial and continuous multi-extremal optimization and importance sampling. This work shows the application of this optimization method to optimize the inputs gains, the location and size of the different membership functions' sets of each variable, as well as the weight of each rule from the rule's base of a fuzzy logic controller (FLC). The control system approach presented in this work was designed to command the orientation of an unmanned aerial vehicle (UAV) to modify its trajectory for avoiding collisions. An onboard looking forward camera was used to sense the environment of the UAV. The information extracted by the image processing algorithm is the only input of the fuzzy control approach to avoid the collision with a predefined object. Real tests with a quadrotor have been done to corroborate the improved behavior of the optimized controllers at different stages of the optimization process.

Structuring research methods and data with the research object model: genomics workflows as a case study

Background: One of the main challenges for biomedical research lies in the computer-assisted integrative study of large and increasingly complex combinations of data in order to understand molecular mechanisms. The preservation of the materials and methods of such computational experiments with clear annotations is essential for understanding an experiment, and this is increasingly recognized in the bioinformatics community. Our assumption is that offering means of digital, structured aggregation and annotation of the objects of an experiment will provide necessary meta-data for a scientist to understand and recreate the results of an experiment. To support this we explored a model for the semantic description of a workflow-centric Research Object (RO), where an RO is defined as a resource that aggregates other resources, e.g., datasets, software, spreadsheets, text, etc. We applied this model to a case study where we analysed human metabolite variation by workflows. Results: We present the application of the workflow-centric RO model for our bioinformatics case study. Three workflows were produced following recently defined Best Practices for workflow design. By modelling the experiment as an RO, we were able to automatically query the experiment and answer questions such as “which particular data was input to a particular workflow to test a particular hypothesis?”, and “which particular conclusions were drawn from a particular workflow?”. Conclusions: Applying a workflow-centric RO model to aggregate and annotate the resources used in a bioinformatics experiment, allowed us to retrieve the conclusions of the experiment in the context of the driving hypothesis, the executed workflows and their input data. The RO model is an extendable reference model that can be used by other systems as well.

Estudio de la fisuración de paneles sándwich de yeso laminado y alma de lana de roca = Study of the cracking of sandwich panels of plasterboard and rockwool

Este artículo presenta el estudio de la rotura de paneles sándwich de yeso laminado y lana de roca bajo solicitaciones de flexo-tracción dentro de su plano. Estos paneles se emplean para conformar tabiques interiores de edificación y con frecuencia se fisuran por flechas excesivas en los forjados. Actualmente no hay modelos de cálculo fiables ni datos experimentales que permitan estudiar este problema. Este trabajo presenta los resultados de una campaña experimental encaminada a caracterizar el comportamiento en rotura de los paneles sándwich y de sus componentes individuales. Además, se presenta un modelo cohesivo con fisura embebida que permite simular el comportamiento en rotura del panel sándwich conjunto. Por último se presentan los resultados de los ensayos de fractura en modo mixto (tracción/cortante) de paneles comerciales y se reproduce su comportamiento con el modelo cohesivo propuesto, obteniéndose un buen ajuste. This paper presents the study of plasterboard and rockwool sandwich panels cracking under flexural loading. These panels are usually used to perform interior partition walls and they frequently show cracking pathology due to excessive deflexion of the slabs. There are currently no reliable simulation models and experimental data for the study of this problem. This paper presents the results of an experimental campaign aimed to characterize the fracture behaviour of sandwich panels and their individual components. In addition, the paper presents a cohesive model with embedded crack to simulate the fracture behaviour of the panel. Finally we present the results of tests for mixed mode fracture (tensile / shear) commercial panels and their behaviour is reproduced with the cohesive model proposed, yielding a good fit.

High-level characteristics of or-and independent and-parallelism in prolog

Although studies of a number of parallel implementations of logic programming languages are now available, their results are difficult to interpret due to the multiplicity of factors involved, the effect of each of which is difficult to sepárate. In this paper we present the results of a high-level simulation study of or- and independent and-parallelism with a wide selection of Prolog programs that aims to determine the intrinsic amount of parallelism, independently of implementation factors, thus facilitating this separation. We expect this study will be instrumental in better understanding and comparing results from actual implementations, as shown by some examples provided in the paper. In addition, the paper examines some of the issues and tradeoffs associated with the combination of and- and or-parallelism and proposes reasonable solutions based on the simulation data obtained.

Integration of temporal and semantic components into the Geographic Information. Part II: Methodology

The overall objective of this research project is to enrich geographic data with temporal and semantic components in order to significantly improve spatio-temporal analysis of geographic phenomena. To achieve this goal, we intend to establish and incorporate three new layers (structures) into the core of the Geographic Information by using mark-up languages as well as defining a set of methods and tools for enriching the system to make it able to retrieve and exploit such layers (semantic-temporal, geosemantic, and incremental spatio-temporal). Besides these layers, we also propose a set of models (temporal and spatial) and two semantic engines that make the most of the enriched geographic data. The roots of the project and its definition have been previously presented in Siabato & Manso-Callejo 2011. In this new position paper, we extend such work by delineating clearly the methodology and the foundations on which we will base to define the main components of this research: the spatial model, the temporal model, the semantic layers, and the semantic engines. By putting together the former paper and this new work we try to present a comprehensive description of the whole process, from pinpointing the basic problem to describing and assessing the solution. In this new article we just mention the methods and the background to describe how we intend to define the components and integrate them into the GI.