ISEP – LSA – Artigos
Permanent URI for this collection
Browse
Browsing ISEP – LSA – Artigos by Title
Now showing 1 - 10 of 82
Results Per Page
Sort Options
- A 2020 perspective on “Online guest profiling and hotel recommendation”Publication . Veloso, Bruno M.; Leal, Fátima; Malheiro, Benedita; Burguillo, Juan CarlosTourism crowdsourcing platforms accumulate and use large volumes of feedback data on tourism-related services to provide personalized recommendations with high impact on future tourist behavior. Typically, these recommendation engines build individual tourist profiles and suggest hotels, restaurants, attractions or routes based on the shared ratings, reviews, photos, videos or likes. Due to the dynamic nature of this scenario, where the crowd produces a continuous stream of events, we have been exploring stream-based recommendation methods, using stochastic gradient descent (SGD), to incrementally update the prediction models and post-filters to reduce the search space and improve the recommendation accuracy. In this context, we offer an update and comment on our previous article (Veloso et al., 2019a) by providing a recent literature review and identifying the challenges laying ahead concerning the online recommendation of tourism resources supported by crowdsourced data.
- A 2020 perspective on “Scalable modelling and recommendation using wiki-based crowdsourced repositories:” Fairness, scalability, and real-time recommendationPublication . Leal, Fátima; Veloso, Bruno; Malheiro, Benedita; González-Vélez, Horacio; Carlos Burguillo, JuanWiki-based crowdsourced data sources generally lack reliability, as their provenance is not intrinsically marshalled. By using recommendation, one may arguably assess the reliability of wiki-based repositories in order to identify the most interesting articles for a given domain. In this commentary, we explore current trends in scalable modelling and recommendation methods based on side information such as the quality and popularity of wiki articles. The systematic parallelization of such profiling and recommendation algorithms allows the concurrent processing of distributed crowdsourced Wikidata repositories. These algorithms, which perform incremental updating, need further research to improve the performance and generate up-to-date high-quality recommendations. This article builds upon our previous work (Leal et al., 2019) by extending the literature review and identifying important trends and challenges pertaining to crowdsourcing platforms, particularly those of Wikidata provenance.
- Air and Underwater Survey of water enclosed spaces for VAMOS! ProjectPublication . Almeida, J.; Ferreira, A.; Matias, B.; Dias, A.; Martins, A.; Silva, F; Oliveira, J.; Sousa, P.; Moreira, M.; Miranda, T.; Almeida, C.; Silva, E.This paper addresses a three-dimensional (3D) reconstruction of a flooded open pit mine with an autonomous surface vehicle (ASV) and unmanned aerial vehicle (UAV). The ROAZ USV and the Otus UAV were used to provide the underwater bathymetric map and aerial 3D reconstruction based from image data. This work was performed wihtin the context of the European researcj project VAMOS with the objective of developing robotic tools for efficient underwater mining
- An automated maneuver control framework for a remotely operated vehiclePublication . Fraga, S. L.; Sousa, J. Borges de; Girard, Anouck; Martins, AlfredoAn automated maneuver control framework for a remotely operate vehicle (ROV) is presented. This framework entails a three-layered control architecture, a principled approach to design and implementation within the architecture, and hybrid systems design techniques. The control architecture is structured according to the principle of composition of vehicle motions from a minimal set of elemental maneuvers that are designed and verified independently. The principled approach is based on distributed hybrid systems techniques, and spans integrated design, simulation and implementation as the same model is used throughout. Hybrid systems control techniques are used to synthesize the elemental maneuvers and to design protocols, which coordinate the execution of elemental maneuvers within a complex maneuver. The architecture is fault-tolerant by design since it uses verified maneuvers. This work is part of the Inspection of Underwater Structures (IES) project whose main objective is the implementation of a ROV-based system for the inspection of underwater structures
- Analysis and prediction of hotel ratings from crowdsourced dataPublication . Leal, Fátima; Malheiro, Benedita; Burguillo, Juan CarlosCrowdsourcing has become an essential source of information for tourism stakeholders. Every day, tourists leave large volumes of feedback data in the form of posts, likes, textual reviews, and ratings in dedicated crowdsourcing platforms. This behavior makes the analysis of crowdsourced information strategic, allowing the discovery of important knowledge regarding tourists and tourism resources. This paper presents a survey on the analysis and prediction of hotel ratings from crowdsourced data, covering both off‐line (batch) and on‐line (stream‐based) processing. Specifically, it reports multiple rating‐based profiling, recommendation, and evaluation techniques. While most of the surveyed works adopt entity‐based multicriteria profiling, prerecommendation filtering, and off‐line processing, the latest hotel rating prediction trends include feature‐based, trust and reputation modeling, postrecommendation filtering, and on‐line processing. Additionally, since the volume of crowdsourced ratings tends to increase, the deployment of profiling and recommendation algorithms on high‐performance computing resources should be further explored.
- Autonomous Surface Vehicle Docking Manoeuvre with Visual InformationPublication . Martins, Alfredo; Almeida, José Miguel; Ferreira, Hugo; Silva, Hugo; Dias, Nuno; Silva, EduardoThis work presents a hybrid coordinated manoeuvre for docking an autonomous surface vehicle with an autonomous underwater vehicle. The control manoeuvre uses visual information to estimate the AUV relative position and attitude in relation to the ASV and steers the ASV in order to dock with the AUV. The AUV is assumed to be at surface with only a small fraction of its volume visible. The system implemented in the autonomous surface vehicle ROAZ, developed by LSA-ISEP to perform missions in river environment, test autonomous AUV docking capabilities and multiple AUV/ASV coordinated missions is presented. Information from a low cost embedded robotics vision system (LSAVision), along with inertial navigation sensors is fused in an extended Kalman filter and used to determine AUV relative position and orientation to the surface vehicle The real time vision processing system is described and results are presented in operational scenario.
- AUV Control and Communication using Underwater Acoustic NetworksPublication . Marques, E.; Pinto, J.; Kragelund, S.; Dias, P.; Madureira, L.; Sousa, A.; Correia, M.; Ferreira, H.; Gonçalves, R.; Martins, R.; Horner, D.; Healey, A. J.; Gonçalves, G.; Sousa, J. B.Underwater acoustic networks can be quite effective to establish communication links between autonomous underwater vehicles (AUVs) and other vehicles or control units, enabling complex vehicle applications and control scenarios. A communications and control framework to support the use of underwater acoustic networks and sample application scenarios are described for single and multi-AUV operation.
- BoaVista – Sensor Dedicado de Visão Artificial Baseado em Hardware (Re)configurávelPublication . Lima, Luís; Almeida, José; Martins, Alfredo; Silva, EduardoEste artigo aborda o projecto de um sistema de visão dedicado para robótica móvel autónoma, que beneficia das capacidades de execução paralela do hardware reconfigurável, processando em “pipeline” as imagens provenientes de um sensor de imagem CMOS de alto desempenho em simultâneo com a aquisição das mesmas. Apresentamos um sistema com a capacidade de adquirir e processar imagens com resoluções de 640x480 a uma taxa de 60 fps, baixo custo e capaz de disponibilizar para o sistema central apenas a informação pretendida extraída da imagem. Este ponto, permite libertar os recursos computacionais do robot traduzindo-se em reduções de consumo significativas e consequente aumento da autonomia energética do mesmo.
- Brokerage Platform for Media Content RecommendationPublication . Veloso, Bruno; Malheiro, Benedita; Burguillo, Juan CarlosNear real time media content personalisation is nowadays a major challenge involving media content sources, distributors and viewers. This paper describes an approach to seamless recommendation, negotiation and transaction of personalised media content. It adopts an integrated view of the problem by proposing, on the business-to-business (B2B) side, a brokerage platform to negotiate the media items on behalf of the media content distributors and sources, providing viewers, on the business-to-consumer (B2C) side, with a personalised electronic programme guide (EPG) containing the set of recommended items after negotiation. In this setup, when a viewer connects, the distributor looks up and invites sources to negotiate the contents of the viewer personal EPG. The proposed multi-agent brokerage platform is structured in four layers, modelling the registration, service agreement, partner lookup, invitation as well as item recommendation, negotiation and transaction stages of the B2B processes. The recommendation service is a rule-based switch hybrid filter, including six collaborative and two content-based filters. The rule-based system selects, at runtime, the filter(s) to apply as well as the final set of recommendations to present. The filter selection is based on the data available, ranging from the history of items watched to the ratings and/or tags assigned to the items by the viewer. Additionally, this module implements (i) a novel item stereotype to represent newly arrived items, (ii) a standard user stereotype for new users, (iii) a novel passive user tag cloud stereotype for socially passive users, and (iv) a new content-based filter named the collinearity and proximity similarity (CPS). At the end of the paper, we present off-line results and a case study describing how the recommendation service works. The proposed system provides, to our knowledge, an excellent holistic solution to the problem of recommending multimedia contents.
- Calibration Method for Underwater Visual Ground-Truth SystemPublication . Faria, André; Almeida, José; Dias, André; Martins, Alfredo; Silva, EduardoThis work presents an automatic calibration method for a vision based external underwater ground-truth positioning system. These systems are a relevant tool in benchmarking and assessing the quality of research in underwater robotics applications. A stereo vision system can in suitable environments such as test tanks or in clear water conditions provide accurate position with low cost and flexible operation. In this work we present a two step extrinsic camera parameter calibration procedure in order to reduce the setup time and provide accurate results. The proposed method uses a planar homography decomposition in order to determine the relative camera poses and the determination of vanishing points of detected lines in the image to obtain the global pose of the stereo rig in the reference frame. This method was applied to our external vision based ground-truth at the INESC TEC/Robotics test tank. Results are presented in comparison with an precise calibration performed using points obtained from an accurate 3D LIDAR modelling of the environment.