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Publications

2019

Negative Space: Workspace Awareness in 3D Face-to-Face Remote Collaboration

Authors
Sousa, M; Mendes, D; dos Anjos, RK; Lopes, DS; Jorge, JA;

Publication
VRCAI

Abstract
Face-to-face telepresence promotes the sense of "being there" and can improve collaboration by allowing immediate understanding of remote people's nonverbal cues. Several approaches successfully explored interactions with 2D content using a see-through whiteboard metaphor. However, with 3D content, there is a decrease in awareness due to ambiguities originated by participants' opposing points-of-view. In this paper, we investigate how people and content should be presented for discussing 3D renderings within face-to-face collaborative sessions. To this end, we performed a user evaluation to compare four different conditions, in which we varied reflections of both workspace and remote people representation. Results suggest potentially more benefits to remote collaboration from workspace consistency rather than people's representation fidelity.We contribute a novel design space, the Negative Space, for remote face-to-face collaboration focusing on 3D content.

2019

Impact of distributed generation on protection and voltage regulation of distribution systems: A review

Authors
Razavi, SE; Rahimi, E; Javadi, MS; Nezhad, AE; Lotfi, M; Shafie khah, M; Catalao, JPS;

Publication
RENEWABLE & SUSTAINABLE ENERGY REVIEWS

Abstract
During recent decades with the power system restructuring process, centralized energy sources are being replaced with decentralized ones. This phenomenon has resulted in a novel concept in electric power systems, particularly in distribution systems, known as Distributed Generation (DG). On one hand, utilizing DG is important for secure power generation and reducing power losses. On the other hand, widespread use of such technologies introduces new challenges to power systems such as their optimal location, protection devices' settings, voltage regulation, and Power Quality (PQ) issues. Another key point which needs to be considered relates to specific DG technologies based on Renewable Energy Sources (RESs), such as wind and solar, due to their uncertain power generation. In this regard, this paper provides a comprehensive review of different types of DG and investigates the newly emerging challenges arising in the presence of DG in electrical grids.

2019

A Comparison Procedure for IMUs Performance

Authors
Mendonça, T; Guimarães, DA; Moreira, AP; Costa, P;

Publication
EPIA (2)

Abstract
Inertial measurement units (IMU) are, typically, a cluster of accelerometers, gyroscopes and magnetometers. Its use was introduced with military applications, being, nowadays, widely common on industrial applications, namely robot navigation. Since there are a lot of units in different cost ranges, it is proposed, in this paper, a procedure to compare their performance in tracking tasks. Once IMU samples are unavoidably corrupted by systematic and stochastic errors, a calibration procedure (without any external equipment) to identify sensors’ error models and a Kalman filter implementation to remove white noise are suggested. Then, the comparison is carried out over two trajectories, square and circular paths, respectively, being described by a robotic arm, which acts as reference. The results show that different manufacturing quality units can track, with success, orientation references but are incapable to perform position tracking activities.

2019

Document in Context of its Time (DICT): Providing Temporal Context to Support Analysis of Past Documents

Authors
Jatowt, A; Campos, R; Bhowmick, SS; Doucet, A;

Publication
PROCEEDINGS OF THE 28TH ACM INTERNATIONAL CONFERENCE ON INFORMATION & KNOWLEDGE MANAGEMENT (CIKM '19)

Abstract
Old documents tend to be difficult to be analyzed and understood, not only for average users but oftentimes for professionals as well. This is due to the context shift, vocabulary evolution and, in general, the lack of precise knowledge about the writing styles in the past. We propose a concept of positioning document in the context of its time, and develop an interactive system to support such an objective. Our system helps users to know whether the vocabulary used by an author in the past were frequent at the time of text creation, whether the author used anachronisms or neologisms, and so on. It also enables detecting terms in text that underwent considerable semantic change and provides more information on the nature of such change. Overall, the proposed tool offers additional knowledge on the writing style and vocabulary choice in documents by drawing from data collected at the time of their creation or at other user-specified time.

2019

Language Modelling Makes Sense: Propagating Representations through Word Net for Full-Coverage Word Sense Disambiguation

Authors
Loureiro, D; Jorge, AM;

Publication
57TH ANNUAL MEETING OF THE ASSOCIATION FOR COMPUTATIONAL LINGUISTICS (ACL 2019)

Abstract
Contextual embeddings represent a new generation of semantic representations learned from Neural Language Modelling (NLM) that addresses the issue of meaning conflation hampering traditional word embeddings. In this work, we show that contextual embeddings can be used to achieve unprecedented gains in Word Sense Disambiguation (WSD) tasks. Our approach focuses on creating sense-level embeddings with full-coverage of WordNet, and without recourse to explicit knowledge of sense distributions or task-specific modelling. As a result, a simple Nearest Neighbors (k-NN) method using our representations is able to consistently surpass the performance of previous systems using powerful neural sequencing models. We also analyse the robustness of our approach when ignoring part-of-speech and lemma features, requiring disambiguation against the full sense inventory, and revealing shortcomings to be improved. Finally, we explore applications of our sense embeddings for concept-level analyses of contextual embeddings and their respective NLMs.

2019

A systematic literature review of machine learning methods applied to predictive maintenance

Authors
Carvalho, TP; Soares, FAAMN; Vita, R; Francisco, RD; Basto, JP; Alcala, SGS;

Publication
COMPUTERS & INDUSTRIAL ENGINEERING

Abstract
The amount of data extracted from production processes has increased exponentially due to the proliferation of sensing technologies. When processed and analyzed, data can bring out valuable information and knowledge from manufacturing process, production system and equipment. In industries, equipment maintenance is an important key, and affects the operation time of equipment and its efficiency. Thus, equipment faults need to be identified and solved, avoiding shutdown in the production processes. Machine Learning (ML) methods have been emerged as a promising tool in Predictive Maintenance (PdM) applications to prevent failures in equipment that make up the production lines in the factory floor. However, the performance of PdM applications depends on the appropriate choice of the ML method. The aim of this paper is to present a systematic literature review of ML methods applied to PdM, showing which are being explored in this field and the performance of the current state-of-the-art ML techniques. This review focuses on two scientific databases and provides a useful foundation on the ML techniques, their main results, challenges and opportunities, as well as it supports new research works in the PdM field.

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