833 research outputs found

    Camouflage of the seahorse Hippocampus reidi with plastic debris : an unusual type of protective resemblance

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    Camouflage is one of the strategies of reef fishes, in which they mimic other species or use the background to match the combination of their colors and textures (Randall 2005). Seahorses of the genus Hippocampus in a pristine habitat generally use saturated colors to camouflage their colorful background using matching or confusing objects as a deceiving mode (Stevens & Merilaita 2011). The present record is the first description of camouflage by the sea horse Hippocampus reidi Ginsburg, 1933 with plastic debris in mangroves from NE Brazil: Formoso River, Tamandaré, Pernambuco State (8°41′01.51″S, 35°06′25.92″ W). […]

    Opportunistic feeding behavior of Diplodus argenteus (Perciformes, Sparidae) : human-fish interaction in two rocky reefs from SE and S Brazil

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    Comportamento alimentar oportunista do marimbá Diplodus argenteus (Perciformes, Sparidae): interação humana-peixe em dois sistemas de costões rochosos do SE e SU do Brasil. Esse artigo aborda dois tipos de comportamentos alimentares do marimbá Diplodus argenteus em dois sistemas de costões rochosos do Atlântico sul no Brasil. Essa espécie alimentou-se sobre o fundo e exibiu comportamentos ocasionais e oportunísticos.ABSTRACT: This report is about two feeding behaviors of the silver porgy Diplodus argenteus in two rock reefs systems from the south Atlantic in Brazil. This species was a bottom feeder, which exhibited occasional and opportunistic behaviors

    A Methodology to Design FPGA-based PID Controllers

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    This paper presents a methodology to implement PID (Proportional, Integral, Derivative) controllers in FPGAs (Field-Programmable Gate Arrays) using fixed-point numerical representation. The Matlab/Simulink environment is used for modeling, simulation and evaluation the performance provided by different fixed-point representations using a given control process. A static bit-width analyzer is used to give a specialized fixed-point representation for each operand/operator in the controller system. After bit-width analysis, a VHDL represen-tation of the system is generated. Results show that the proposed methodology leads to shorten design cycles achieving important resource savings by employing specialized fixed-point repre-sentations

    Solar Irradiance (Global, Direct and Diffuse) Quality Control Methodologies. Review: Application to Time Series Measured At LES/LNEG, Lisboa, Portugal

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    ABSTRACT: Solar irradiance spatial and temporal quantification is essential to the development, implementation, and operation of solar systems, being used throughout a solar project lifecycle. It is crucial to have good quality data measured in meteorological and radiometric ground stations in order to enable the calibration and validation of irradiance models and data series. The Solar Energy laboratory at LNEG operates a meteorological station gathering relevant parameters to characterize the solar irradiation profile for the city of Lisbon in Portugal. This work presents and compares the application of different methodologies used for quality control of solar irradiance measurements. Three methods - the CIE (1994) / Muneer and Fairooz (2002), the QCRad and the IEC - were tested against two synthetic data sets: a clear-sky year and a typical meteorological year randomly and uniformly infused with errors. IEC showed to have limitation regarding the extreme value criteria for beam normal irradiance and CIE for the diffuse horizontal irradiance. The QCRad presented the best performance, with total sensitivity above 80% and maximum specificity. This method was applied to the measured data of LES-LNEG between 2014 and 2018. Most of the detected errors were detected during the coherence test stage, having a higher prevalence between 2015 and mid-2016, highlighting the need to modify the diffuse horizontal irradiance measuring system.info:eu-repo/semantics/publishedVersio

    Satisfiability-Based Algorithms for Boolean Optimization

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    Processing of continuous fibre reinforced thermoplastics

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    ECCM15 - 15TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS, Venice, Italy, 24-28 June 2012Towpregs based on different fibres and thermoplastic matrices were processed for highly demanding and more commercial applications by different composite processing technologies. In the technologies used, compression moulding and pultrusion, the final composite pr ocessing parameters were studied in order to obtain composites with adequate properties at industrial compatible production rates. The produced towpregs were tested to verify its polymer content and degree of impregnation. The obtained results have shown t hat the coating line enabled to produce, with efficiency and industrial scale speed rates, thermoplastic matrix towpregs that may be used to manufacture composites for advanced and larger volume commercial markets

    Automatic Vehicle Trajectory Extraction by Aerial Remote Sensing

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    Research in road users’ behaviour typically depends on detailed observational data availability, particularly if the interest is in driving behaviour modelling. Among this type of data, vehicle trajectories are an important source of information for traffic flow theory, driving behaviour modelling, innovation in traffic management and safety and environmental studies. Recent developments in sensing technologies and image processing algorithms reduced the resources (time and costs) required for detailed traffic data collection, promoting the feasibility of site-based and vehicle-based naturalistic driving observation. For testing the core models of a traffic microsimulation application for safety assessment, vehicle trajectories were collected by remote sensing on a typical Portuguese suburban motorway. Multiple short flights over a stretch of an urban motorway allowed for the collection of several partial vehicle trajectories. In this paper the technical details of each step of the methodology used is presented: image collection, image processing, vehicle identification and vehicle tracking. To collect the images, a high-resolution camera was mounted on an aircraft's gyroscopic platform. The camera was connected to a DGPS for extraction of the camera position and allowed the collection of high resolution images at a low frame rate of 2s. After generic image orthorrectification using the flight details and the terrain model, computer vision techniques were used for fine rectification: the scale-invariant feature transform algorithm was used for detection and description of image features, and the random sample consensus algorithm for feature matching. Vehicle detection was carried out by median-based background subtraction. After the computation of the detected foreground and the shadow detection using a spectral ratio technique, region segmentation was used to identify candidates for vehicle positions. Finally, vehicles were tracked using a k- shortest disjoints paths algorithm. This approach allows for the optimization of an entire set of trajectories against all possible position candidates using motion-based optimization. Besides the importance of a new trajectory dataset that allows the development of new behavioural models and the validation of existing ones, this paper also describes the application of state-of-the-art algorithms and methods that significantly minimize the resources needed for such data collection. Keywords: Vehicle trajectories extraction, Driver behaviour, Remote sensin
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