Isotropic Image Analysis for Improving CBR Forecasting

A novel hybrid forecasting Case-Based Reasoning (CBR) system is presented in this interdisciplinary study in which an isotropic buffer operator is applied for case-based creation. Commonly used as an image analysis technique by commercial Geographic Information Systems (GIS), the buffer operator in this particular system calculates the area of an oil slick for prediction and visualization tasks. The use of the buffer operator improves the quality of the data used by the system and in consequence the quality of the results obtained. The system generates predictions by using historical data on oil-slick formation following a spill

(OBIFS) isotropic image analysis for improving a predicting agent based systems

In this interdisciplinary study a novel hybrid forecasting system is presented, in which an isotropic buffer operator is applied for case-based creation within the structure of the organization-based multi-agent system. Commonly used as an image analysis technique by commercial Geographic Information Systems (GIS), the buffer operator in this particular system calculates the area of a forest fire for prediction and visualization tasks. The use of the buffer operator improves the quality of the data used by the system and in consequence the quality of the results obtained. The system has been successfully tested using real historical data on forest fires evolution, by generating accurate predictions

Aeronautical engineering: A continuing bibliography with indexes (supplement 214)

This bibliography lists 422 reports, articles and other documents introduced into the NASA scientific and technical information system in May, l987

Optimización del diseño estructural de pavimentos asfálticos para calles y carreteras

gráficos, tablasThe construction of asphalt pavements in streets and highways is an activity that requires optimizing the consumption of significant economic and natural resources. Pavement design optimization meets contradictory objectives according to the availability of resources and users’ needs. This dissertation explores the application of metaheuristics to optimize the design of asphalt pavements using an incremental design based on the prediction of damage and vehicle operating costs (VOC). The costs are proportional to energy and resource consumption and polluting emissions. The evolution of asphalt pavement design and metaheuristic optimization techniques on this topic were reviewed. Four computer programs were developed: (1) UNLEA, a program for the structural analysis of multilayer systems. (2) PSO-UNLEA, a program that uses particle swarm optimization metaheuristic (PSO) for the backcalculation of pavement moduli. (3) UNPAVE, an incremental pavement design program based on the equations of the North American MEPDG and includes the computation of vehicle operating costs based on IRI. (4) PSO-PAVE, a PSO program to search for thicknesses that optimize the design considering construction and vehicle operating costs. The case studies show that the backcalculation and structural design of pavements can be optimized by PSO considering restrictions in the thickness and the selection of materials. Future developments should reduce the computational cost and calibrate the pavement performance and VOC models. (Texto tomado de la fuente)La construcción de pavimentos asfálticos en calles y carreteras es una actividad que requiere la optimización del consumo de cuantiosos recursos económicos y naturales. La optimización del diseño de pavimentos atiende objetivos contradictorios de acuerdo con la disponibilidad de recursos y las necesidades de los usuarios. Este trabajo explora el empleo de metaheurísticas para optimizar el diseño de pavimentos asfálticos empleando el diseño incremental basado en la predicción del deterioro y los costos de operación vehicular (COV). Los costos son proporcionales al consumo energético y de recursos y las emisiones contaminantes. Se revisó la evolución del diseño de pavimentos asfálticos y el desarrollo de técnicas metaheurísticas de optimización en este tema. Se desarrollaron cuatro programas de computador: (1) UNLEA, programa para el análisis estructural de sistemas multicapa. (2) PSO-UNLEA, programa que emplea la metaheurística de optimización con enjambre de partículas (PSO) para el cálculo inverso de módulos de pavimentos. (3) UNPAVE, programa de diseño incremental de pavimentos basado en las ecuaciones de la MEPDG norteamericana, y el cálculo de costos de construcción y operación vehicular basados en el IRI. (4) PSO-PAVE, programa que emplea la PSO en la búsqueda de espesores que permitan optimizar el diseño considerando los costos de construcción y de operación vehicular. Los estudios de caso muestran que el cálculo inverso y el diseño estructural de pavimentos pueden optimizarse mediante PSO considerando restricciones en los espesores y la selección de materiales. Los desarrollos futuros deben enfocarse en reducir el costo computacional y calibrar los modelos de deterioro y COV.DoctoradoDoctor en Ingeniería - Ingeniería AutomáticaDiseño incremental de pavimentosEléctrica, Electrónica, Automatización Y Telecomunicacione

High Frame Rate Ultrasound Velocimetry of Fast Blood Flow Dynamics

In this thesis we develop and validate high frame rate ultrasound sequences for use with echo-particle image velocimetry (in 2D and 3D), with the aim of measuring the high velocity blood flow patterns in the left ventricle and abdominal aorta

New Class Of Exact Solutions To Einstein-Maxwell-Dilaton Theory On Four-Dimensional Bianchi Type IX Geometry

We construct new classes of cosmological solution to the five dimensional Einstein-Maxwell-dilaton theory, that are non-stationary and almost conformally regular everywhere. The base geometry for the solutions is the four-dimensional Bianchi type IX geometry. In the theory, the dilaton field is coupled to both the electromagnetic field and the cosmological constant term, with two different coupling constants. We consider all possible solutions with different values of the coupling constants, where the cosmological constant takes any positive, negative or zero values. In the ansatzes for the metric, dilaton and electromagnetic fields, we consider dependence on time and two spatial directions. We also consider a special case of the Bianchi type IX geometry, in which the geometry reduces to that of Eguchi-Hanson type II geometry and find a more general solution to the theory

Wave breaking at high wind speeds and its effects on air-sea gas transfer

Gravity waves are ubiquitous at the surface of the ocean and play a key role in the coupled ocean-atmosphere system. These wind generated waves, for which gravity provides the restoring force, influence the kinematics and dynamics of the upper ocean and lower atmosphere. Their breaking injects turbulence into the upper ocean, generates bubble plumes and sea-spray thus transferring energy, momentum, heat and mass between the atmosphere and the ocean. In the anthropocene, with CO2 driving the warming trend and the ocean acting as the main carbon sink, it is imperative to understand the complex physical controls of air-sea gas transfer. Large uncertainties still remain under high wind speed conditions where wave breaking processes are dominant. This dissertation seeks to shed light onto the dependence of wave breaking and air-sea gas transfer on environmental parameters. It further explores process based models of air-sea gas transfer that explicitly account for the breaking related processes. Air entraining breaking waves are easily detectable as bright features on the ocean surface composed of foam and subsurface bubble plumes. These features, termed whitecaps, arise at wind speed as as low as 3 m s−1 . The whitecap coverage (W) has been recognized as a useful proxy for quantifying wave breaking related processes. It can be determined from shipboard, air-borne and satellite remote sensing. W is most commonly parameterized as a function of wind speed, but previous parameterizations display over three orders of magnitude scatter. Concurrent wave field and flux measurements acquired during the Southern Ocean Gas Exchange (SO GasEx) and the High Wind Gas exchange Study (HiWinGS) projects permitted evaluation of the dependence of W on wind speed, wave age, wave steepness, mean square slope, as well as on wave-wind and breaking Reynolds numbers. W was determined from over 600 high frequency visible imagery recordings of 20 minutes each. Wave statistics were computed from in situ and remotely sensed data as well as from a WAVEWATCH-III® hind cast. The first ship-borne estimates of W under sustained wind speeds (U10N ) of 25 m s−1 were obtained during HiWinGS. These measurements suggest that W levels off at high wind speed, not exceeding 10% when averaged over 20 minutes. Combining wind speed and wave height in the form of the wave-wind Reynolds number resulted in closely agreeing models for both datasets, individually and combined. These are also in good agreement with two previous studies. When expressing W in terms of wave field statistics only or wave age, larger scatter is observed and/or there is little agreement between SO GasEx, HiWinGS, and previously published data. The wind–speed-only parameterizations deduced from the SO GasEx and HiWinGS datasets agree closely and capture more of the observed W variability than Reynolds number parameterizations. However, these wind-speed-only models do not agree as well with previous studies than the wind-wave Reynolds numbers. The ability to quantify air-sea gas transfer hinges on parameterizations of the gas transfer velocity k. k represents physical mass transfer mechanisms and is usually parameterized as a non-linear function of wind forcing. Previous eddy-covariance measurements and models based on the global radio carbon inventory led to diverging parameterizations with both cubic and quadratic wind speed dependence. At wind speeds above 10 m s−1 these parameterizations differ considerably and measurements display large scatter. In an attempt to reduce uncertainties in k, explored empirical parameterizations that incorporate both wind speed and sea state dependence via breaking and wave-wind Reynolds numbers, were explored. Analysis of concurrent eddy covariance gas transfer and measured wave field statistics supplemented by wave model hindcasts shows for the first time that wave-related Reynold numbers collapse four open ocean datasets that have a wind speed dependence of CO2 transfer velocity ranging from lower than quadratic to cubic. Wave-related Reynolds number and wind speed show comparable performance for parametrizing DMS which, because of its higher solubility, is less affected by bubble-mediated exchange associated with wave breaking. While single parameter models may be readily used in climate studies, their application is gas specific and may be limited to select environments. Physically based parameterizations that incorporate multiple forcing factors allow to model the gas transfer of gases with differing solubility for a wide range of environmental conditions. Existing mechanistic models were tested and a novel framework to model gas transfer in the open ocean in the presence of breaking waves is put forward. This analysis allowed to update NOAA’s Coupled OceanAtmosphere Response Experiment Gas transfer algorithm (COAREG) and exposed limitation of other existing physically based parameterizations. The newly proposed mechanistic model incorporates both the turbulence and bubble mediated transfer. It is based on various statistics determined from the breaking crest length distribution (Λ(c)). Λ(c) was obtained by tracking the advancing front of breaking waves in the high frequency videos taken during HiWinGS. Testing the mechanistic model with the HiWinGS dataset shows promising results for both CO2 and DMS, though it does not perform better than COAREG. Uncertainties remain in the quantification of bubble cloud which are at the core of the formulation of the bubble mediated transfer and additional field measurements are necessary to characterize bubble plume properties in the open ocean

Performance evaluation of realistic scenarios for vehicular ad hoc networks with VanetMobiSim and NS2

Català: En els darrers anys, el considerable creixement del sector dels serveis mòbils arreu del món es certament el major fenòmen al camp de les telecomunicaciones. Les tecnologies inalàmbriques han conduït al desenvolupament de nous sistemes de comunicació y serveis multimèdia. Degut al constant creixement del mercat automobilístic juntament amb la creixent demanda de la seguretat viària ha nascut un nou concepte al camp de les comunicaciones: les xarxes entre vehicles (VANETs). A les VANETs, cada vehicle pot actuar com a router o node, establint connexions entre vehicles propers o amb infraestructura a la carretera. Les VANET estan rebent més atenció del govern i de la indústria automobilística degut a l'àmplia varietat d'aplicacions y serveis que poden oferir, tal com sistemes de seguretet viària assistència a la carretera i accès a Internet. No obstant, el disseny i l'implementació de VANETs és una àrea d'investigació àmplia i complexa tal i com podem percebre, sabent que durant els darrers anys la comunitat investigadora s'ha centrat en l'estudi d'aquestes xarxes. Bàsicament, el nostre projecte està dividit en dues parts principals: Primerament, hem dut a terme una recerca relacionada amb l'estat actual de les VANET avui en dia, amb l'objectiu d'identificar els generadors de moviment i els simuladors de xarxes més apropiats i recomenats a la literatura. En segon lloc, hem decidit utilitzar el VanetMobiSim [80], com a generador de moviment degut a la seva varietat de models de movilitat que es poden testejar, i el NS2 [63] com a simulador de xarxes per ser un dels més utilitzats per molts autors a més de la seva compatibilitat amb el VanetMobiSim. Amb l'ús d'aquestes eines, VanetMobiSim i NS2, hem dut a terme una avaluació profunda de les prestacions de les VANET en diversos escenaris reals, assignant valors diferents a paràmetres tals com el nombre de nodes, la velocitat i el model de propagació.Castellano: En los últimos años, el considerable crecimiento del sector de los servicios móviles alrededor del mundo es con certeza el mayor fenómeno en el campo de las telecomunicaciones. Las tecnologías inalámbricas han conducido al desarrollo de nuevos sistemas de comunicación y servicios multimedia. Debido al constante crecimiento del mercado automovilístico y la creciente demanda en seguridad vial ha nacido un nuevo concepto en el campo de las comunicaciones: las redes entre vehículos (VANETs). En ellas, cada vehículo actúa como router, estableciendo conexiones entre vehículos cercanos o con infraestructura en la carretera. Las VANET estan recibiendo más atención del gobierno y de la industria automovilística debido a la amplia variedad de aplicaciones y servicios que puede ofrecer, tales como sistemas de seguridad vial, asistencia en carretera y acceso a Internet. Sin embargo, el diseño e implementación de las VANET es un area de investigación amplia y compleja, tal y como podemos percibir, sabiendo que durante los últimos años la comunidad investigadora se ha centrado en el estudio de estas redes. Básicamente, nuestro proyecto está dividido en dos partes principales: Primeramente, hemos llevado a cabo una búsqueda relacionada con el estado de arte de las VANET hoy en día, con el objetivo de identificar los generadores de movimiento i los simuladores de redes más apropiados i recomendados en la literatura. En segundo lugar, hemos decidido utilizar el VanetMobiSim [80], como generador de movimiento debido a la alta variedad de modelos de mobilidad que que se pueden testear, y el NS2 [63] como simulador de redes por ser uno de los más utilizados per muchos autores además de su compatibilidad con el VanetMobiSim. Con el uso de estas herramientas, hemos llevado a cabo una evaluación profunda de las prestaciones de las VANET en varios escenarios reales, asignando valores diferentes a parámetros tales como el número de nodos, la velocidad y el modelo de propagación.English: Over recent years, the considerable mobile services sector growth around the world was certainly the major phenomenon in the telecommunications field. Wireless technology has led to the development of new communications systems and multimedia services. Due to the continued growth of the vehicular industry and the increasing demand of road safety, a new concept in the communications field was born: vehicular networks (VANETs). In VANETs, each vehicle could act as router or node, establishing connections among nearby vehicles or with roadside infrastructure. VANETs are receiving more attention from governments and car manufacturers due to the wide variety of applications and services they can provide such as road safety systems, car assistance and Internet acces. However, designing and implementing VANETs is a complex and wide area of research as we can notice, knowing that in the last years the research and development community has focused on the study of such networks. Basically, our project is divided in two main parts: Firstly, we made a state of art related to the actual state of VANETs nowadays in order to find the most appropiate and recommended mobility generator and network simulator reported in the literature. Secondly, we decided to use VanetMobiSim [80], as a mobility generator due to its variety mobility models that could be tested, and NS2 [63] as a network simulator for being one of the most used by many authors and also due to its compatibilty with VanetMobiSim. Using these tools, VanetMobiSim and NS2, we carried out a deep performance evaluation of VANETs in several realistic scenarios, giving different values to parameters such as the number of nodes, speed and the propagation model

Deep learning approaches to multimodal MRI brain age estimation

Brain ageing remains an intricate, multifaceted process, marked not just by chronological time but by a myriad of structural, functional, and microstructural changes that often lead to discrepancies between actual age and the age inferred from neuroimaging. Machine learning methods, and especially Convolutional Neural Networks (CNNs), have proven adept in capturing patterns relating to ageing induced changes in the brain. The differences between the predicted and chronological ages, referred to as brain age deltas, have emerged as useful biomarkers for exploring those factors which promote accelerated ageing or resilience, such as pathologies or lifestyle factors. However, previous studies relied overwhelmingly on structural neuroimaging for predictions, overlooking rich details inherent in other MRI modalities, such as potentially informative functional and microstructural changes. This research, utilising the extensive UK Biobank dataset, reveals that 57 different maps spanning structural, susceptibility-weighted, diffusion, and functional MRI modalities can not only predict an individual's chronological age, but also encode unique ageing-related details. Through the use of both 3D CNNs and the novel 3D Shifted Window (SWIN) Transformers, this work uncovered associations between brain age deltas and 191 different non-imaging derived phenotypes (nIDPs), offering a valuable insight into factors influencing brain ageing. Moreover, this work found that ensembling data from multiple maps results in higher prediction accuracies. After a thorough comparison of both linear and non-linear multi-modal ensembling methods, including deep fusion networks, it was found that linear methods, such as ElasticNet, generally outperform their more complex non-linear counterparts. In addition, while ensembling was found to strengthen age prediction accuracies, it was found to weaken nIDP associations in certain circumstances where ensembled maps might have opposing sensitivities to a particular nIDP, thus reinforcing the need for guided selections of the ensemble components. Finally, while both CNNs and SWINs show comparable brain age prediction precision, SWIN networks stand out for their robustness against data corruption, while also proving a degree of inherent explainability. Overall, the results presented herein demonstrate that other 3D maps and modalities, which have not been considered previously for the task of brain age prediction, encode different information about the ageing brain. This research lays the foundation for further explorations into how different factors, such as off-target drug effects, impact brain ageing. It also ushers in possibilities for enhanced clinical trial design, diagnostic approaches, and therapeutic monitoring grounded in refined brain age prediction models