2018
Authors
Gatzioura, A; Marrè, MS; Jorge, AM;
Publication
Artificial Intelligence Research and Development - Current Challenges, New Trends and Applications, CCIA 2018, 21st International Conference of the Catalan Association for Artificial Intelligence, Alt Empordà, Catalonia, Spain, 8-10th October 2018
Abstract
Recommender systems still mainly base their reasoning on pairwise interactions or information on individual entities, like item attributes or ratings, without properly evaluating the multiple dimensions of the recommendation problem. However, in many cases, like in music, items are rarely consumed in isolation, thus users rather need a set of items, selected to work well together, serving a specific purpose, while having some cognitive properties as a whole, related to their perception of quality and satisfaction, under given circumstances. In this paper, we introduce the term of playlist concept in order to capture the implicit characteristics of joint music item selections, related to their context, scope and general perception by the users. Although playlist consumptions may be associated with contextual attributes, these may be of various types, differently influencing users' preferences, based on their character and emotional state, therefore differently reflected on their final selections. We highlight on the use of this term in HybA, our hybrid recommender system, to identify clusters of similar playlists able to capture inherit characteristics and semantic properties, not explicitly described in them. The experimental results presented, show that this conceptual clustering results in playlist continuations of improved quality, compared to using explicit contextual parameters, or the commonly used collaborative filtering technique. © 2018 The authors and IOS Press.
2018
Authors
De Almeida J.M.M.M.; Vasconcelos H.; Jorge P.A.S.; Coelho L.;
Publication
Optics InfoBase Conference Papers
Abstract
Refractive index sensors based on localized surface plasmon resonance are presented through the fabrication of gold nano-islands on top of optical fiber tips. Repeated dewetting process led to an increase of sensitivity from 60 to 186nm/RIU.
2018
Authors
Baltazar, S; Barreto, L; Amaral, A;
Publication
2018 IEEE INTERNATIONAL CONFERENCE ON ENGINEERING, TECHNOLOGY AND INNOVATION (ICE/ITMC)
Abstract
A new integrated approach is required for planning and rethinking mobility issues in European Regions, towards allowing them to become better prepared into near future challenges. In this paper, a set of recommendations for future mobility planning in the Alto Minho Region, in Northern Portugal, will be proposed taking into consideration social inclusion and environmental concerns into accessibility planning. The conducted research shows that despite different framework methods and approaches, similar trends emerge in future mobility, reinforcing that cooperative actions to share information and encourage dialogue between all stakeholders (population, politicians and operators) in long term plans is essential. Based on Gini-coefficients assessment and its resulting spider diagrams, a population profile is created aiming to explore the impacts in future mobility solutions. As the result of this approach, this paper presents some key recommendations for future mobility planning, based on an integrated delivery of policies for social and environmental equity within the transportation sector.
2018
Authors
Trentadue G.; Lucas A.; Otura M.; Pliakostathis K.; Zanni M.; Scholz H.;
Publication
Energies
Abstract
Multi-type fast charging stations are being deployed over Europe as electric vehicle adoption becomes more popular. The growth of an electrical charging infrastructure in different countries poses different challenges related to its installation. One of these challenges is related to weather conditions that are extremely heterogeneous due to different latitudes, in which fast charging stations are located and whose impact on the charging performance is often neglected or unknown. The present study focused on the evaluation of the electric vehicle (EV) charging process with fast charging devices (up to 50 kW) at ambient (25°C) and at extreme temperatures (-25°C, -15°C, +40°C). A sample of seven fast chargers and two electric vehicles (CCS (combined charging system) and CHAdeMO (CHArge de Move)) available on the commercial market was considered in the study. Three phase voltages and currents at the wall socket, where the charger was connected, as well as voltage and current at the plug connection between the charger and vehicle have been recorded. According to SAE (Society of Automotive Engineers) J2894/1, the power conversion efficiency during the charging process has been calculated as the ratio between the instantaneous DC power delivered to the vehicle and the instantaneous AC power supplied from the grid in order to test the performance of the charger. The inverse of the efficiency of the charging process, i.e., a kind of energy return ratio (ERR), has been calculated as the ratio between the AC energy supplied by the grid to the electric vehicle supply equipment (EVSE) and the energy delivered to the vehicle's battery. The evaluation has shown a varied scenario, confirming the efficiency values declared by the manufacturers at ambient temperature and reporting lower energy efficiencies at extreme temperatures, due to lower requested and, thus, delivered power levels. The lowest and highest power conversion efficiencies of 39% and 93% were observed at -25°C and ambient temperature (+25°C), respectively.
2018
Authors
Oliveira, JN;
Publication
JOURNAL OF LOGICAL AND ALGEBRAIC METHODS IN PROGRAMMING
Abstract
This paper presents a study of the metaphorism pattern of relational specification, showing how it can be refined into recursive programs. Metaphorisms express input-output relationships which preserve relevant information while at the same time some intended optimization takes place. Text processing, sorting, representation changers, etc., are examples of metaphorisms. The kind of metaphorism refinement studied in this paper is a strategy known as change of virtual data structure. By framing metaphorisms in the class of (inductive) regular relations, sufficient conditions are given for such implementations to be calculated using relation algebra. The strategy is illustrated with examples including the derivation of the quicksort and mergesort algorithms, showing what they have in common and what makes them different from the very start of development.
2018
Authors
Costa, D; Diogo, CC; da Costa, LM; Pereira, JE; Filipe, V; Couto, PA; Geuna, S; Armada Da Silva, PA; Mauricio, AC; Varejao, ASP;
Publication
NEUROLOGICAL RESEARCH
Abstract
Functional recovery following general nerve reconstruction is often associated with poor results. Comparing to rat and mice experimental studies, there are much fewer investigations on nerve regeneration and repair in the sheep, and there are no studies on this subject using gait analysis in the sheep model as an assessment tool. Additionally, this is the first study evaluating obstacle negotiation and the compensatory strategies that take place at each joint in response to the obstacle during locomotion in the sheep model. This study aims to get kinematic data to serve as a template for an objective assessment of the ankle joint motion in future studies of common peroneal nerve (CP) injury and repair in the ovine model. Our results show that a moderately high obstacle set to 10% of the sheep's hindlimb length was associated to several spatial and temporal strategies in order to increase hoof height during obstacle negotiating. Sheep efficiently cleared an obstacle by increasing knee, ankle and metatarsophalangeal flexion during swing, whereas the hip joint is not affected. This study establishes the bounds of normal motion in the neurologically intact hindlimb when approached and cleared an obstacle and provides baseline data for further studies of peripheral nerve research in the ovine model.
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