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Publications

2020

Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination

Authors
Gomes, AD; Ferreira, MS; Bierlich, J; Kobelke, J; Rothhardt, M; Bartelt, H; Frazao, O;

Publication
OPTICS AND LASER TECHNOLOGY

Abstract
Achieving a new generation of enhanced sensors requires the development of structures that result from the fusion of different concepts and effects. In this paper, we combine a special strain sensing structure with an optical sensitivity magnification, through harmonics of the Vernier effect. The recently demonstrated harmonics of the Vernier effect result from increasing the optical path length (OPL) of one of two interferometers by multiple times the OPL of the other interferometer. The effect generates higher magnification factors, proportional to the order of the harmonics. The sensing structure is demonstrated for strain and temperature discrimination, allowing compensation for temperature fluctuations. We explore the complex case of the optical Vernier effect in series, where both interferometers are used as sensing interferometers (no reference interferometer is used). Our results also suggest that the magnification enhancement provided by harmonics of the Vernier effect for a configuration in series is the same as for a configuration in parallel: the magnification factor increases proportionally to the order of the harmonics.

2020

Impact of different sensory stimuli on presence in credible virtual environments

Authors
Goncalves, G; Melo, M; Vasconcelos Raposo, J; Bessa, M;

Publication
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS

Abstract

2020

On the Trade-Offs of Combining Multiple Secure Processing Primitives for Data Analytics

Authors
Carvalho, H; Cruz, D; Pontes, R; Paulo, J; Oliveira, R;

Publication
Distributed Applications and Interoperable Systems - 20th IFIP WG 6.1 International Conference, DAIS 2020, Held as Part of the 15th International Federated Conference on Distributed Computing Techniques, DisCoTec 2020, Valletta, Malta, June 15-19, 2020, Proceedings

Abstract
Cloud Computing services for data analytics are increasingly being sought by companies to extract value from large quantities of information. However, processing data from individuals and companies in third-party infrastructures raises several privacy concerns. To this end, different secure analytics techniques and systems have recently emerged. These initial proposals leverage specific cryptographic primitives lacking generality and thus having their application restricted to particular application scenarios. In this work, we contribute to this thriving body of knowledge by combining two complementary approaches to process sensitive data. We present SafeSpark, a secure data analytics framework that enables the combination of different cryptographic processing techniques with hardware-based protected environments for privacy-preserving data storage and processing. SafeSpark is modular and extensible therefore adapting to data analytics applications with different performance, security and functionality requirements. We have implemented a SafeSpark’s prototype based on Spark SQL and Intel SGX hardware. It has been evaluated with the TPC-DS Benchmark under three scenarios using different cryptographic primitives and secure hardware configurations. These scenarios provide a particular set of security guarantees and yield distinct performance impact, with overheads ranging from as low as 10% to an acceptable 300% when compared to an insecure vanilla deployment of Apache Spark. © IFIP International Federation for Information Processing 2020.

2020

Towards Predicting Pedestrian Paths: Identifying Surroundings from Monocular Video

Authors
Cruz, JA; Rúbio, TRPM; Jacob, J; Garrido, D; Cardoso, HL; Silva, DC; Rodrigues, R;

Publication
Intelligent Data Engineering and Automated Learning - IDEAL 2020 - 21st International Conference, Guimaraes, Portugal, November 4-6, 2020, Proceedings, Part II

Abstract
Pedestrian behavior is an essential subject of study when developing or enhancing urban infrastructure. However, most behavior elicitation techniques are inherently bound to be biased by either the observer, the subject, or the environment. The SIMUSAFE project aims at collecting road users’ behavioral data in naturalistic and realistic scenarios to produce more accurate decision-making models. Using video captured from a monocular camera worn by a pedestrian, we employ machine learning and computer vision techniques to identify areas of interest surrounding a pedestrian. Namely, we use object detection and depth estimation to generate a map of obstacles that may influence the pedestrian’s actions. Our methods have shown to be successful in detecting free and occupied areas from monocular video. © 2020, Springer Nature Switzerland AG.

2020

Rapid learning of complex sequences with time constraints: A dynamic neural field model

Authors
Ferreira, F; Wojtak, W; Sousa, E; Louro, L; Bicho, E; Erlhagen, W;

Publication
IEEE Transactions on Cognitive and Developmental Systems

Abstract

2020

How Knowledge Acquisition Diversity Affects Innovation Performance during the Technological Catch-Up in Emerging Economies: A Moderated Inverse U-Shape Relationship

Authors
Li, Q; Guo, JJ; Liu, W; Yue, XG; Duarte, N; Pereira, C;

Publication
SUSTAINABILITY

Abstract
Many domestic enterprises in emerging economies are concerned with the question of how to better utilize the portfolio of technology sourcing channels to achieve rapid economic growth by technological innovation. This paper looks at this issue by exploring the impacts of knowledge acquisition diversity (KAD) on innovation performance of domestic enterprises in China and the technological contexts (in terms of technology gap and technology development speed) under which KAD is most likely to contribute. Using panel data of the manufacturing industry in China over the 2001-2009 period, the results show that KAD has an inverse U-shaped relationship with innovation performance in terms of both product-related innovation performance (NPS) and knowledge-related innovation performance (PAT). Specifically, it reveals that the capability to generate technological innovation over time is dependent on how domestic enterprises manage their portfolio of knowledge sourcing channels to learn from foreign enterprises. Moreover, it is shown that the technology gap significantly moderates the inverted U-shaped relationship between KAD and both NPS and PAT. Technology development speed has a moderating effect on the inverted U-shaped relationship between KAD and innovation only in terms of NPS. The results of this study can help us to understand the relationships among technological contexts, KAD and innovation performance of domestic enterprises in emerging countries.

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