CRAS - Indexed Articles in Conferences

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    Hydrodynamic Modeling and Motion Limits of AUV MARES
    ( 2009) Miguel Armando Pinto ; Bruno Miguel Ferreira ; Aníbal Matos ; Nuno Cruz
    This papers addresses the dynamic characterization of the autonomous underwater vehicle MARES. The paper presents the main dynamic properties of this underwater robotic platform as well as the procedures employed to obtain the parameters that define the vehicle model. Furthermore, the paper also presents a detailed characterization of the elementary motions that this vehicle is able to perform.
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    Side Scan Sonar Image Segmentation and Feature Extraction
    ( 2009) Bruno Miguel Ferreira ; Aníbal Matos ; Nuno Cruz ; Miguel Armando Pinto
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    Using Side Scan Sonar to Relative Navigation
    ( 2009) Miguel Armando Pinto ; Aníbal Matos ; Bruno Miguel Ferreira ; Nuno Cruz
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    Using Side Scan Sonar for Relative Navigation
    ( 2009) Nuno Cruz ; Miguel Armando Pinto ; Aníbal Matos ; Bruno Miguel Ferreira
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    Control of the MARES Autonomous Underwater Vehicle
    ( 2009) Aníbal Matos ; Bruno Miguel Ferreira ; Miguel Armando Pinto
    This paper focuses the control problem of a nonholonomic autonomous underwater vehicle, moving in the tridimensional space. The dynamic of a body in submarine environments is strongly nonlinear. This implies that classical linear controllers are often inadequate whereby Lyapunov theory is here considered. Methods based in this theory are promising tools to design controllers and are applied to the case of MARES, a small-sized autonomous underwater vehicle. Several controllers based only on Lyapunov theory are determined while others combine linear and nonlinear control theory in order to perform various maneuvers. Aiming to verify the correct performance of controllers, simulations and experiments are carried out.
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    Single beacon navigation: localization and control of the MARES AUV
    ( 2010) Nuno Cruz ; Aníbal Matos ; Bruno Miguel Ferreira
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    "Experiment@Portugal"
    ( 2011) Maria Teresa Restivo ; Alberto Cardoso ; Alves,J
    The main goal of the Project Experiment@Portugal is to produce a complete survey of Portuguese developments in remote and virtual labs. This knowledge will provide the conditions for joining forces in order to organize a well structured national website integrating a database of available remote and virtual experiments, categorized for sharing purposes, and looking for delivering valuable contents for high schools and for higher education. It is expected that the final result will bring up a solid team able to offer in this domain a Portuguese partner at international level.
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    Sensing Structure based on Surface Plasmonic Resonance in Single Mode Optical Fibers Chemically Etched
    ( 2013) Luís Carlos Coelho ; José Almeida ; José Luís Santos ; Ferreira,RAS ; Andre,PS ; Diana Viegas
    Many optical systems based on Surface Plasmon Resonance (SPR) have been developed for work as refractometers, chemical sensors or even for measure the thickness of metal and dielectric thin films. These kinds of systems are usually large, expensive and cannot be used for remote sensing. Optical fiber sensors based on SPR has been widely studied for the last 20 years with several configurations mostly using multimode optical fibers with large cores and plastic claddings. Sensors based on SPR present very high sensitivity to refractive index variations when compared to the traditional refractive index sensors. Here we propose a SPR sensor based in a single mode fiber. The fiber end is chemically etched by emersion in a 48% hydrofluoric acid solution, resulting a single mode fiber with the cladding removed in a small section. A resonance dip around 1580 nm was attained in good agreement with the simulation scenario that takes into account the real characteristics of the fiber.
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    Personalised advertising supported by agents
    ( 2013) Bruno Miguel Veloso ; Sousa,L ; Benedita Malheiro
    This paper reports the development of a B2B platform for the personalization of the publicity transmitted during the program intervals. The platform as a whole must ensure that the intervals are filled with ads compatible with the profile, context and expressed interests of the viewers. The platform acts as an electronic marketplace for advertising agencies (content producer companies) and multimedia content providers (content distribution companies). The companies, once registered at the platform, are represented by agents who negotiate automatically the price of the interval timeslots according to the specified price range and adaptation behaviour. The candidate ads for a given viewer interval are selected through a matching mechanism between ad, viewer and the current context (program being watched) profiles. The overall architecture of the platform consists of a multiagent system organized into three layers consisting of: (i) interface agents that interact with companies; (ii) enterprise agents that model the companies, and (iii) delegate agents that negotiate a specific ad or interval. The negotiation follows a variant of the Iterated Contract Net Interaction Protocol (ICNIP) and is based on the price/s offered by the advertising agencies to occupy the viewer's interval. © Springer International Publishing Switzerland 2013.
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    Analysis of phase interrogation in SPR-based sensing supported by tapered optical fibres
    ( 2013) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Diana Viegas
    An analytical model based on geometrical optics and multilayer transfer matrix method is applied to the surface plasmonic resonance supported by fibre taper structures in the context of optical sensing applications. Phase interrogation is considered in particular as a methodology to attain enhanced sensitivities, and the performance of the sensing heads as function of the metal clad and taper parameters is analyzed. General topics concerning the actual relevance of plasmonics are also presented, first in a global perspective and then when applied to sensing.
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    SPR Sensing with Bimetallic Layers in Optical Fibers and Phase Interrogation
    ( 2013) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Diana Viegas
    An analytical model based on geometrical optics and multilayer transfer matrix method is applied to determine the sensing properties of tapered optical fiber based SPR sensors incorporating bimetallic (Gold and Silver) layers, particularly when phase interrogation is considered. Phase interrogation is studied as a methodology to attain enhanced sensitivities. The performance of the sensing heads as function of the bimetallic layers and taper parameters is analyzed. It is shown the bimetallic combination is capable to provide larger values of sensitivity compared with the single layer approach. The results derived from this study are guiding the experimental study of these structures.
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    A framework for hardware cellular genetic algorithms: An application to spectrum allocation in cognitive radio
    ( 2013) Dos Santos,PV ; José Carlos Alves ; João Canas Ferreira
    The genetic algorithm (GA) is an optimization metaheuristic that relies on the evolution of a set of solutions (population) according to genetically inspired transformations. In the variant of this technique called cellular GA, the evolution is done separately for subgroups of solutions. This paper describes a hardware framework capable of efficiently supporting custom accelerators for this metaheuristic. This approach builds a regular array of problem-specific processing elements (PEs), which perform the genetic evolution, connected to shared memories holding the local subpopulations. To assist the design of the custom PEs, a methodology based on highlevel synthesis from C++ descriptions is used. The proposed architecture was applied to a spectrum allocation problem in cognitive radio networks. For an array of 5×5 PEs in a Virtex-6 FPGA, the results show a minimum speedup of 22× compared to a software version running on a PC and a speedup near 2000× over a MicroBlaze soft processor. © 2013 IEEE.
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    Analysis of Phase Interrogated SPR Fiber Optic Sensors with Different Bimetallic Combinations
    ( 2014) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Ariel Guerreiro ; Diana Viegas
    Optical fiber sensors based on the phenomenon of plasmonic resonance can be interrogated applying different methods, the most common one being the spectral approach where the measurand information is derived from the reading of the wavelength resonance dip. In principle, a far better performance can be achieved considering the reading of the phase of the light at a specific wavelength located within the spectral plasmonic resonance. This approach is investigated in this work for surface plasmon based fiber optic sensors with overlays which are combinations of bimetallic layers, permitting not only to tune the wavelength of the plasmon resonance but also the sensitivity associated with the phase interrogation of the sensors. The metals considered for the present analysis are silver, gold, copper, and aluminum.
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    A game for robot operation training in Search and Rescue missions
    ( 2014) Goncalves,R ; Ricardo José Baptista ; António Coelho ; Aníbal Matos ; de Carvalho,CV ; Bedkowski,J ; Musialik,P ; Ostrowski,I ; Majek,K
    Search and rescue (SAR) teams often face several complex and dangerous tasks, which could be aided by unmanned robotic vehicles (UV). UV agents can potentially be used to decrease the risk in the loss of lives both of the rescuers and victims and aid in the search and transportation of survivors and in the removal of debris in a catastrophe scenario. Depending on the nature of a catastrophe and its geographical location, there are potentially three types of UVs that can be deployed: aerial, surface and ground. Due to the control and manipulation particularities each type of UV contemplates, their operators need prior training and certification. To train and certify the operators a tool (serious game) is under development. In this paper we will make an overview about our approach in its development. This game uses a typical client-server architecture where all client agents (virtual UVs and operator client interfaces) share the same immersive virtual environment which is generated through the merging of GIS data and a semantic model extracted from 3D laser data. There will be several types of scenarios suitable to several types of catastrophe situations. Each of these scenarios has its own mission plan for the trainees to follow. The game will also provide an interface for mission planning so that each mission plan will be carefully designed to accurately correspond to a matrix of skills. This matrix lists a set of common skills in various different UV operational case studies which will allow the certification of operators.
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    Probabilistic stereo egomotion Transform
    ( 2014) Hugo Miguel Silva ; Eduardo Silva ; Bernardino,A
    In This paper we propose a novel fully probabilistic solution To The stereo egomotion estimation problem. We extend The notion of probabilistic correspondence To The stereo case which allow us To compute The whole 6D motion information in a probabilistic way. We compare The developed approach against other known state-of-the-Art methods for stereo egomotion estimation, and The obtained results compare favorably both for The linear and angular velocities estimation. © 2014 IEEE.
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    Optical sensing based in plasmonics and the metamaterials enhancement factor
    ( 2014) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; Santos,JL ; Ariel Guerreiro ; Diana Viegas
    The recent burst of R&D activity in Plasmonics, associated with the possibility of materials nanostructuring which enables the access to metamaterials, has been strongly impacting many branches of optics such as imaging, data recording and sensing. This talk details the factors that turned the combination Plasmonics and Metamaterials a huge opportunity to optical sensing.© OSA 2014.
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    Designing search and rescue robots towards realistic user requirements
    ( 2014) Doroftei,D ; Aníbal Matos ; de Cubber,G
    In the event of a large crisis (think about typhoon Haiyan or the Tohoku earthquake and tsunami in Japan), a primordial task of the rescue services is the search for human survivors on the incident site. This is a complex and dangerous task, which often leads to loss of lives among the human crisis managers themselves. The introduction of unmanned search and rescue devices can offer a valuable tool to save human lives and to speed up the search and rescue process. In this context, the EU-FP7-ICARUS project [1] concentrates on the development of unmanned search and rescue technologies for detecting, locating and rescuing humans. The complex nature and difficult operating conditions of search and rescue operations pose heavy constraints on the mechanical design of the unmanned platforms. In this paper, we discuss the different user requirements which have an impact of the design of the mechanical systems (air, ground and marine robots). We show how these user requirements are obtained, how they are validated, how they lead to design specifications for operational prototypes which are tested in realistic operational conditions and we show how the final mechanical design specifications are derived from these different steps. An important aspect of all these design steps which is emphasized in this paper is to always keep the end-users in the loop in order to come to realistic requirements and specifications, ensuring the practical deployability [2] of the developed platforms. © (2014) Trans Tech Publications, Switzerland.