2018
Authors
Melo, M; Vasconcelos Raposo, J; Bessa, M;
Publication
COMPUTERS & GRAPHICS-UK
Abstract
As the usage of head-mounted displays (HMD) increases, it is important to establish best usage practices to ensure the appropriate use of Virtual Reality (VR) equipment. Among the factors that can contribute to a better user experience are exposure time, the content type and the gender of the user. This study evaluates the impact of these variables on users' Sense of Presence and Cybersickness when visualising 360 content using HMDs. Two types of 360 content (captured video vs. virtual environment) were evaluated across four different exposure times (1, 3, 5 and 7 min). Regarding Sense of Presence, the results revealed a statistically significant difference for Content Type, Gender, and Content Type x Gender. Regarding Cybersickness, no statistically significant results were found for any of the independent variables. Overall, the results encourage the use of synthesized environments for a female audience; for non-interactive environments, captured environments are more effective than synthesized environments; and exposure time is not a concern for experiences lasting between 1 and 7 min.
2018
Authors
Pedro, AD; Pinto, JS; Pereira, D; Pinho, LM;
Publication
INTERNATIONAL JOURNAL ON SOFTWARE TOOLS FOR TECHNOLOGY TRANSFER
Abstract
Current real-time embedded systems development frameworks lack support for the verification of properties using explicit time where counting time (i.e., durations) may play an important role in the development process. Focusing on the real-time constraints inherent to these systems, we present a framework that addresses the specification of duration properties for runtime verification by employing a fragment of metric temporal logic with durations. We also provide an overview of the framework, the synthesis tools, and the library to support monitoring properties for real-time systems developed in C++11. The results obtained provide clear evidence of the feasibility and advantages of employing a duration-sensitive formalism to increase the dependability of avionic controller systems such as the PX4 and the Ardupilot flight stacks.
2018
Authors
Ribeiro, C; Rocha da Silva, J; Aguiar Castro, J; Carvalho Amorim, R; Correia Lopes, J; David, G;
Publication
IASSIST Quarterly
Abstract
2018
Authors
Campos, R; Mangaravite, V; Pasquali, A; Jorge, AM; Nunes, C; Jatowt, A;
Publication
ADVANCES IN INFORMATION RETRIEVAL (ECIR 2018)
Abstract
In this paper, we present YAKE!, a novel feature-based system for multi-lingual keyword extraction from single documents, which supports texts of different sizes, domains or languages. Unlike most systems, YAKE! does not rely on dictionaries or thesauri, neither it is trained against any corpora. Instead, we follow an unsupervised approach which builds upon features extracted from the text, making it thus applicable to documents written in many different languages without the need for external knowledge. This can be beneficial for a large number of tasks and a plethora of situations where the access to training corpora is either limited or restricted. In this demo, we offer an easy to use, interactive session, where users from both academia and industry can try our system, either by using a sample document or by introducing their own text. As an add-on, we compare our extracted keywords against the output produced by the IBM Natural Language Understanding (IBM NLU) and Rake system. YAKE! demo is available at http://bit.ly/YakeDemoECIR2018. A python implementation of YAKE! is also available at PyPi repository (https://pypi.python.org/pypi/yake/).
2018
Authors
Neves, R; Barbosa, LS;
Publication
THEORETICAL COMPUTER SCIENCE
Abstract
We study hybrid automata from a coalgebraic point of view. We show that such a perspective supports a generic theory of hybrid automata with a rich palette of definitions and results. This includes, among other things, notions of bisimulation and behaviour, state minimisation techniques, and regular expression languages.
2018
Authors
Brito, PQ; Stoyanova, J; Coelho, A;
Publication
MULTIMEDIA TOOLS AND APPLICATIONS
Abstract
The moment immediately before the "add to cart" decision is very critical in online shopping. Drawing on theories of transfer, spreading activation and human-computer interaction, the superiority of markerless Augmented Reality (AR) and Marker-based augmented reality (M) over Conventional Interactive (CI) is hypothesized. Although those multimedia tools are not part of the product/brand motivating the consumer interest they interfere in the interactive performance of the ecommerce. 150 consumers in a lab experiment showed higher emotional response, interactive response and brand evaluation in M and AR than CI. Contrary to what was expected the usability results were the inverse. That is, usability of CI outperforms M and AR. Considering only AR and M interfaces their effect on psychological variables was not statistically significant. A sophisticated or a simple interface had no impact on intention to buy the target brand, but the brand recommendation improved from M to AR. The differing effect of those three interface systems was mediated by brand familiarity, perceived risk, opinion leadership and positive emotional traits.
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