4,608 research outputs found

    On the Utility of the Inverse Gamma Distribution in Modeling Composite Fading Channels

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    We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative density function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model, and in some relevant cases, as a mixture of well-known state-of-the-art distributions. We exemplify our approach by presenting a composite IG/two-wave with diffuse power fading model, for which its statistical characterization is directly attained in a simple form.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Model ensembles of ecosystem services fill global certainty and capacity gaps

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    UK Research & Innovation (UKRI) NE/W005050/1 NE/T00391X/1 ES/R009279/1 ES/T007877/1 ES/V004077/1 ES/R006865/1National Science Foundation (NSF) NSF - Office of the Director (OD) 08695Next Generation European Union fundsUKCEHSpanish Government DGE-213989

    Vehicle pose estimation using G-Net: multi-class localization and depth estimation

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    In this paper we present a new network architecture, called G-Net, for 3D pose estimation on RGB images which is trained in a weakly supervised manner. We introduce a two step pipeline based on region-based Convolutional neural networks (CNNs) for feature localization, bounding box refinement based on non-maximum-suppression and depth estimation. The G-Net is able to estimate the depth from single monocular images with a self-tuned loss function. The combination of this predicted depth and the presented two-step localization allows the extraction of the 3D pose of the object. We show in experiments that our method achieves good results compared to other state-of-the-art approaches which are trained in a fully supervised manner.Peer ReviewedPostprint (author's final draft

    Performance analysis of MIMO-OFDM systems using complex Gaussian quadratic forms

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    En este trabajo se proponen aportaciones originales para el análisis de prestaciones en sistemas multiantena con múltiples portadoras, mediante el desarrollo de nuevas técnicas matemáticas para el cálculo de probabilidades de error. Así, ha sido posible analizar el efecto de no idealidades (estimación de canal imperfecta, offset de continua, desbalanceo I/Q…) en las prestaciones de sistemas de comunicaciones móviles e inalámbricas

    Are Floods Becoming a More Expensive Hazard? A Damages Review of the Southeastern Spanish Coast (1996–2016).

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    Over the last few decades, an increasing economic and social flooding damages trend has been recorded worldwide. Although this situation was initially associated with climate change, recently different institutions and scientific papers have related this trend to two main reasons: (i) a human population increase and (ii) the number of assets located in floodable areas. In this regard, this paper analyses evolutions in flood damages and their causes in a Mediterranean area, the provinces of Alicante and Murcia, between 1996 and 2016. The duration of this period, from a flood risk management policy point of view, is very important because it encompasses one of the most important legislative periods at a national and European level. As a main result, this paper establishes a temporal and spatial pattern related to increases in flood damages and their main influence on coastal areas, respectively, due to certain economic, spatial and temporal factors. As a conclusion, these trends demonstrate the inefficiency of flood risk management policies, especially those connected with spatial planning.Partial funding for open access charge: Universidad de Málag

    Assessing habitat diversity and potential areas of similarity across protected areas globally

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    Biophysical characterization analyses of protected areas (PA) that provide information on their ecological values and potential areas with similar characteristics are needed to make informed PA network planning and management decisions. This study combines and further develops methodologies that use remote sensing and modelling to identify habitat functional types in PAs and map similar areas at the ecoregion level. The study also develops new terrestrial habitat diversity and irreplaceability indices at habitat and PA scale that allow the comparison and ranking of PAs in terms of biophysical gradients and singular environmental conditions. Six PAs were selected to highlight and discuss the results of the proposed methodology. Both individual and composite indices should be considered when trying to compare PAs to understand the overall complexity and ecological values of each PA. Results can inform planning and management of individual and protected area networks as well as identify new areas for conservation. The information provided by the model about similar habitats outside protected areas can also help assess their representativeness and support studies to strengthen ecological connectivity. Besides systematic comparisons, detailed assessments of protected areas can also be performed using medium and high-resolution input variables. This is especially relevant for protected areas in developing countries where undertaking fieldwork is very difficult and the budget devoted to conservation is limited.European Commission European Commission Joint Research CentreBiodi- versity and Protected Areas Management (BIOPAMA) programme, an initiative of the African, Caribbean and Pacific (ACP) Group of StatesMarie Curie Actions CT-EX2020D381533-101Spanish Ministry of Universities and Next Generation European Union fund

    Construction of a taxonomy for requirements engineering commercial-off-the-shelf components

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    This article presents a procedure for constructing a taxonomy of COTS products in the field of Requirements Engineering (RE). The taxonomy and the obtained information reach transcendental benefits to the selection of systems and tools that aid to RE-related actors to simplify and facilitate their work. This taxonomy is performed by means of a goal-oriented methodology inspired in GBRAM (Goal-Based Requirements Analysis Method), called GBTCM (Goal-Based Taxonomy Construction Method), that provides a guide to analyze sources of information and modeling requirements and domains, as well as gathering and organizing the knowledge in any segment of the COTS market. GBTCM claims to promote the use of standards and the reuse of requirements in order to support different processes of selection and integration of components.Peer ReviewedPostprint (published version

    Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient)

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    The present work analyses the natural ventilation of a multi-span greenhouse with one roof vent and two side vents by means of sonic anemometry. Opening the roof vent to windward, one side vent to leeward, and the other side vents to windward (this last vent obstructed by another greenhouse), causes opposing thermal GT (m3 s−1) and wind effects Gw (m3 s−1), as outside air entering the greenhouse through the roof vent circulates downward, contrary to natural convection due to the thermal effect. In our case, the ventilation rate RM (h−1) in a naturally ventilated greenhouse fits a second order polynomial with wind velocity uo (RM = 0.37 uo2 + 0.03 uo + 0.75; R2 = 0.99). The opposing wind and thermal effects mean that ventilation models based on Bernoulli’s equation must be modified in order to add or subtract their effects accordingly—Model 1, in which the flow is driven by the sum of two independent pressure fields GM1=√(∣∣G2T±G2w∣∣) , or Model 2, in which the flow is driven by the sum of two independent fluxes GM2=|GT±Gw| . A linear relationship has been obtained, which allows us to estimate the discharge coefficient of the side vents (CdVS) and roof vent (CdWR) as a function of uo [CdVS = 0.028 uo + 0.028 (R2 = 0.92); CdWR = 0.036 uo + 0.040 (R2 = 0.96)]. The wind effect coefficient Cw was determined by applying models M1 and M2 proved not to remain constant for the different experiments, but varied according to the ratio uo/∆Tio0.5 or δ [CwM1 = exp(−2.693 + 1.160/δ) (R2 = 0.94); CwM2 = exp(−2.128 + 1.264/δ) (R2 = 0.98)]

    Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria

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    Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusively found in cyanobacteria. TrxC has a modified active site (WCGLC) instead of the canonical (WCGPC) present in most thioredoxins. We have purified it and assayed its activity but surprisingly TrxC lacked all the classical activities, such as insulin precipitation or activation of the fructose-1,6-bisphosphatase. Mutants lacking trxC or over-expressing it were generated in the model cyanobacterium Synechocystis sp. PCC 6803 and their phenotypes have been analyzed. The ΔtrxC mutant grew at similar rates to WT in all conditions tested although it showed an increased carotenoid content especially under low carbon conditions. Overexpression strains showed reduced growth under the same conditions and accumulated lower amounts of carotenoids. They also showed lower oxygen evolution rates at high light but higher Fv’/Fm’ and Non-photochemical-quenching (NPQ) in dark adapted cells, suggesting a more oxidized plastoquinone pool. All these data suggest that TrxC might have a role in regulating photosynthetic adaptation to low carbon and/or high light conditions.España, MINECO BIO2016-75634-PJunta de Andalucía P12-BIO-1119 , BIO-28
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