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Browsing by Issue Date, starting with "2020-02-25"

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  • Bidirectional data transfer in VLC links
    Publication . Louro, Paula; Vieira, Manuela; Vieira, Manuel Augusto
    Visible Light communication is a data transmission technology that uses the LED lighting infrastructure to simultaneously illuminate and communicate. The ubiquitous existence of LED lamps opened a new opportunity for addressing VLC communication in many indoor communication scenarios. The motivation for the application presented in this paper is the modern, efficient management of warehouses supported by autonomous navigation robots that grab goods and deliver the items at the packaging station. This functionality demands bi-directional communication among infrastructures and vehicles. In this paper we propose links for Infrastructure-To-Vehicle (I2V), Vehicle-ToInfrastructure (V2I) and Vehicle-To-Vehicle (V2V) to perform indoors, bi-directional communication for robot navigation in automated warehouses. In this work it is proposed a bidirectional communication system between a static infrastructure and a mobile robot (I2V). The LED lamps of the warehouse illumination system are used to lighten the space, and to transmit information about position and about racks content. The mobile robots communicate with the infrastructure (V2I) to transmit information on the items that are being removed and carried to the packaging station. The communication among the autonomous robots (V2V) provides information on the number of items intended to be collected when the vehicles are in the same lane, possibly with the purpose of collecting the same items. Different codification schemes are proposed to establish the V2I, I2V and V2V links. Tri-chromatic white LEDs with the red and blue chips modulated at different frequencies and a photodetector based on a-SiC:H/a-Si:H with selective spectral sensitivity are used at the emitter and receiver. Position information is provided by each LED lamp to the autonomous vehicle by adequate modulation of the RGB emitters. The decoding strategy is based on accurate calibration of the output signal. Different scenarios were designed and tested. Requirements related to synchronous transmission and flickering were addressed to enhance the system performance.
    2020-02-25Conference object Restricted access Show more
  • Application of a novel approach to modelling the supercritical extraction kinetics of oil from two sets of chia seeds
    Publication . Villanueva Bermejo, David; Fornari, Tiziana; Calvo, Maria V.; FONTECHA, JAVIER; Coelho, Jose; Filipe, Rui; Stateva, Roumiana P.
    The kinetics of the supercritical fluid extraction of edible and discarded chia seeds was studied and modelled for the first time. The total oil was removed at 45 MPa and 60 degrees C after 240 min. The extraction kinetics was simulated using a dynamic model in gPROMS ModelBuilder environment and the kinetic parameters estimated. Triolein was chosen as a model compound of the chia oil. The agreement between the experimental yields and those calculated by the model was good with deviations in the range (1.2-6.6) %, except at 25 MPa and 60 degrees C (AARD = 9.5%). (C) 2019 The Korean Society of Industrial and Engineering Chemistry.
    2020-02-25Journal article Open access Show more