A Framework for Evaluating Land Use and Land Cover Classification Using Convolutional Neural Networks

Analyzing land use and land cover (LULC) using remote sensing (RS) imagery is essential for many environmental and social applications. The increase in availability of RS data has led to the development of new techniques for digital pattern classification. Very recently, deep learning (DL) models have emerged as a powerful solution to approach many machine learning (ML) problems. In particular, convolutional neural networks (CNNs) are currently the state of the art for many image classification tasks. While there exist several promising proposals on the application of CNNs to LULC classification, the validation framework proposed for the comparison of different methods could be improved with the use of a standard validation procedure for ML based on cross-validation and its subsequent statistical analysis. In this paper, we propose a general CNN, with a fixed architecture and parametrization, to achieve high accuracy on LULC classification over RS data from different sources such as radar and hyperspectral. We also present a methodology to perform a rigorous experimental comparison between our proposed DL method and other ML algorithms such as support vector machines, random forests, and k-nearest-neighbors. The analysis carried out demonstrates that the CNN outperforms the rest of techniques, achieving a high level of performance for all the datasets studied, regardless of their different characteristics.Ministerio de Economía y Competitividad TIN2014-55894-C2-1-RMinisterio de Economía y Competitividad TIN2017-88209-C2-2-

Huelva, al final de la huida de Sanjurjo : Verano de 1932

La intentona militar contra la II República española, protagonizada por el General Sanjurjo en Agosto de 1932 es una acontecimiento suficientemente conocido, como conocidas son muchas de las circunstancias que rodean este suceso y su importancia en el conjunto de la vida política republicana. En este artículo se analiza el hecho de la detención del general sedicioso y la cohorte que le acompañaba en la ciudad de Huelva. Se parte para ello de un telegrama encontrado en el Archivo Histórico Nacional de Madrid y dirigido al entonces Ministro de Gobernación, Casares Quiroga, por el gobernador civil de Huelva. Lo que pudiera ser un simple dato anecdótico(apoyado por las versiones de la prensa onubense) se convierte en la corroboración de la tesis que mantiene que Sanjurjo huía a Portugal pero que no tuvo inconveniente en entregarse a las autoridades de Huelva una vez sorprendido, abortando así su huida y evitando ser apresado por las autoridades sevillanas que el mismo había depuesto. Las circunstancias que rodearon esta detención, la implicación de importantes personajes de la vida política onubense y nacional, el comportamiento de los socialistas y los partidos de republicanos, la actitud del gobernador y de algunos ministros y una intervención parlamentaria sobre el asunto nos permiten algunas conclusiones sobre la debilidad de la II República y las relaciones de poder que en ella se daban. Señalar por último el hecho de la detención en sus diferentes relatos, puestos de manifiesto en este trabajo, así como la concreción sobre el lugar, el momento y las circunstancias que se dieron en la detención del general Sanjurjo y su séquito, durante una madrugada de agosto en el Barrio Obrero de Huelva._________________________________The military putsch against Spanish Second Republic, leadered by General Sanjurjo in August 1932, is a well-known event. In the same way, the circumstances of the happenings concerning this issue and their importance within the republic political life are also famous. In this article, the fact of the arrest of this seditious general and of those that accompanied him in the town of Huelva is analysed. The starting-point is the telegram, found in the National Historic Archive in Madrid, addressed to the Minister of Government at that moment, Casares Quiroga, by the Provincial Governor of Huelva. This simple anecdotal detail supports the thesis that considers that Sanjurjo was running away to Portugal, but that he did not have any objection to surrender in front of the authorities of Huelva when he was discovered. In this way, the general fails his escape and prevents from being caught by authorities from Seville, which he himself had banished. Those factors that surround this arrest, the implication of relevant people of national and local political life, the socialist and republican parties' behaviours, the government's attitudes, and the intervention of parliament and of some ministers on the issue allow us to come to some conclusions on the weakness of the Second Republic and on the relations of power at the time. To conclude, it is important to analyse the fact of the arrest in its different readings, brough to light in this article. Moreover, it is also interesting to study the connection about the place, time and circumstances that happened in the arrests of general Sanjurjo and his followers at dawn in August in El Barrio Obrero in Huelva. Obrero in Huelva

English phrasal verbs in the production of L2 learners: are phrasal verbs that difficult for L1 spanish speakers?

Los verbos frasales son considerados uno de los aspectos mas difíciles de la gramática inglesa para los estudiantes de lenguas segundas. Este trabajo investiga algunas de las razones que subyacen a esta dificultad a través del análisis de datos obtenidos de un grupo de nativos de español que estudian inglés como segunda lengua. El análisis de datos revela que (1) estos participantes muestran una preferencia clara por evitar el uso de verbos frasales y los sustituyen por verbos léxicos sin partícula y que (2) el conocimiento gramatical de este tipo de verbos es en general muy reducido. El estudio apunta a la combinación de factores responsables de esta dificultad entre los que están los siguientes: las propiedades gramaticales de los verbos frasales, la metodología usada en la enseñanza y la influencia interlingüística de la lengua nativa.Departamento de Filología InglesaGrado en Estudios Inglese

Inhomogeneities and caustics in the sedimentation of noninertial particles in incompressible flows

In an incompressible flow, fluid density remains invariant along fluid element trajectories. This implies that the spatial distribution of non-interacting noninertial particles in such flows cannot develop density inhomogeneities beyond those that are already introduced in the initial condition. However, in certain practical situations, density is measured or accumulated on (hyper-) surfaces of dimensionality lower than the full dimensionality of the flow in which the particles move. An example is the observation of particle distributions sedimented on the floor of the ocean. In such cases, even if the initial distribution of noninertial particles is uniform within a finite support in an incompressible flow, advection in the flow will give rise to inhomogeneities in the observed density. In this paper we analytically derive, in the framework of an initially homogeneous particle sheet sedimenting towards a bottom surface, the relationship between the geometry of the flow and the emerging distribution. From a physical point of view, we identify the two processes that generate inhomogeneities to be the stretching within the sheet, and the projection of the deformed sheet onto the target surface. We point out that an extreme form of inhomogeneity, caustics, can develop for sheets. We exemplify our geometrical results with simulations of particle advection in a simple kinematic flow, study the dependence on various parameters involved, and illustrate that the basic mechanisms work similarly if the initial (homogeneous) distribution occupies a more general region of finite extension rather than a sheet.Comment: 56 pages, 17 figure

Obstacle alert and collision avoidance system development for UAVs with Pixhawk flight controller

In recent years, the unmanned aerial vehicles sector has been characterized by its sharp growth, spreading its line of applications and becoming one of the cutting edge technologies in the world. However, this exponential advancement would have been even more extreme but for the restrictive existing legislation that limits its operations. That constraints imposed to drone operations are not legislated in vain. Specially in populated areas, flying drones is a dangerous service that entails risks for the safety of the population. Useless have been the attempts of many major online selling companies to make use of unmanned aerial vehicles serving as dealers of parcels. Further technology needs still to be implemented, for guarantying standards levels of safety in urban zones. This thesis aims to contribute to this required development of drone technology by proposing a preliminary collision avoidance system for unmanned aerial vehi- cles. The project involves assembling a flight-capable quadcopter from scratch and implementing the collision avoidance as an additional subsystem. To that end, a set of ultrasonic range finders are located around the quadcopter. Their acquired raw data is processed in an auxiliary arduino microcontroller board that send tra- jectory corrections to the flight controller of the quadcopter based on the distance information. As a result, a concept proof of an autonomous collision avoidance system is integrated into an unmanned aerial vehicle system. Results are obtained and consecutively analyzed based on ground and flight tests. For that purpose, the flight capabilities of the built quadcopter are proved, and aftewards, the collision avoidance is tested. Overall, the collision avoidance system e ectiveness was achieved. The collision avoidance work principle consisted on warding off from obstacles when detected. Major faced problems are related to stability recover after the collision is avoided. That problem was solved by proving different flight modes, but that issue needs future work to make the collision avoidance more reliable.Ingeniería Aeroespacia

Hydrodynamic provinces and oceanic connectivity from a transport network help designing marine reserves

Oceanic dispersal and connectivity have been identified as crucial factors for structuring marine populations and designing Marine Protected Areas (MPAs). Focusing on larval dispersal by ocean currents, we propose an approach coupling Lagrangian transport and new tools from Network Theory to characterize marine connectivity in the Mediterranean basin. Larvae of different pelagic durations and seasons are modeled as passive tracers advected in a simulated oceanic surface flow from which a network of connected areas is constructed. Hydrodynamical provinces extracted from this network are delimited by frontiers which match multi-scale oceanographic features. By examining the repeated occurrence of such boundaries, we identify the spatial scales and geographic structures that would control larval dispersal across the entire seascape. Based on these hydrodynamical units, we study novel connectivity metrics for existing reserves. Our results are discussed in the context of ocean biogeography and MPAs design, having ecological and managerial implications

Comparison between Eulerian diagnostics and finite-size Lyapunov exponents computed from altimetry in the Algerian basin

Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and submesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in detecting instantaneaous and climatological transport and mixing properties. By comparing with sea-surface temperature patterns, we find that the two diagnostics provide similar results for slowly evolving eddies like the first Alboran gyre. However, the Lyapunov exponent is also able to predict the (sub-)mesoscale filamentary process occuring along the Algerian current and above the Balearic Abyssal Plain. Such filaments are also observed, with some mismatch, in sea-surface temperature patterns. Climatologies of Lyapunov exponents do not show any compact relation with other Eulerian diagnostics, unveiling a different structure even at the basin scale. We conclude that filamentation dynamics can be detected by reprocessing available altimetric data with Lagrangian tools, giving insight into (sub-)mesoscale stirring processes relevant to tracer observations and complementing traditional Eulerian diagnostics

Lagrangian transport in a microtidal coastal area: the Bay of Palma, island of Mallorca, Spain

Coastal transport in the Bay of Palma, a small region in the island of Mallorca, Spain, is characterized in terms of Lagrangian descriptors. The data sets used for this study are the output for two months (one in autumn and one in summer) of a high resolution numerical model, ROMS, forced atmospherically and with a spatial resolution of 300 m. The two months were selected because its different wind regime, which is the main driver of the sea dynamics in this area. Finite-size Lyapunov Exponents (FSLEs) were used to locate semi-persistent Lagrangian coherent structures (LCS) and to understand the different flow regimes in the Bay. The different wind directions and regularity in the two months have a clear impact on the surface Bay dynamics, whereas only topographic features appear clearly in the bottom structures. The fluid interchange between the Bay and the open ocean was tudied by computing particle trajectories and Residence Times (RT) maps. The escape rate of particles out of the Bay is qualitatively different, with a 32$$ more of escape rate of particles to the ocean in October than in July, owing to the different geometric characteristics of the flow. We show that LCSs separate regions with different transport properties by displaying spatial distributions of residence times on synoptic Lagrangian maps together with the location of the LCSs. Correlations between the time-dependent behavior of FSLE and RT are also investigated, showing a negative dependence when the stirring characterized by FSLE values moves particles in the direction of escape