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Publications

2016

Editorial

Authors
Pinho, LM;

Publication
Ada User Journal

Abstract

2016

Walrasian prices in random exchange markets

Authors
Bruno M P M Oliveira; Ahmad, Yusuf Aliyu; Yannacopoulos, Athanasios N; Finkenstädt, Barbel F; Pinto, Alberto A;

Publication

Abstract

2016

ANALYSIS OF WELL-BEING IN OECD COUNTRIES THROUGH STATIS METHODOLOGY

Authors
Rivadeneira, FJ; Figueiredo, AMS; Figueiredo, FOS; Carvajal, SM; Rivadeneira, RA;

Publication
HOLOS

Abstract
This paper presents the main concepts and results of a Master thesis in Data Analysis which aims to analyze the evolution of some developed countries and also of some emerging countries that are members of the Organisation for Economic Co-operation and Development (OECD) in what concerns some indicators or variables of well-being during the period 2011-2015, through the STATIS (Structuring Three-way data sets in Statistics) methodology. This methodology allows to analyze the presence of a common structure in several data tables obtained over time, to identify the differences and similarities along the period of time under study and according to well-being indicators included in the "Your Better Life Index" of the OECD, and to analyze the trajectories of the countries.

2016

Safe operation of transmission system considering EV at distribution level

Authors
Gouveia, EM; Costa, PM; Sagredo, J; Soroudi, A;

Publication
2016 IEEE 16TH INTERNATIONAL CONFERENCE ON ENVIRONMENT AND ELECTRICAL ENGINEERING (EEEIC)

Abstract
In this paper, the IEEE 14 bus test system is used in order to perform adequacy assessment of a transmission system when large scale integration of electric vehicles is considered at distribution levels. In this framework, the symmetric/constrained fuzzy power flow (SFPF/CFPF) was proposed. The SFPF/CFPF models are suitable to quantify the adequacy of transmission network to satisfy "reasonable demands for the transmission of electricity" as defined, for instance, in the European Directive 2009/72/EC. In this framework, electric vehicles of different types will be treated as fuzzy loads configuring part of the "reasonable demands". With this study, it is also intended to show how to evaluate the amount of EVs that can be safely accommodated to the grid meeting a certain adequacy level.

2016

SafeRegions: Performance evaluation of multi-party protocols on HBase

Authors
Pontes, R; Maia, F; Paulo, J; Vilaca, R;

Publication
2016 IEEE 35TH INTERNATIONAL SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS WORKSHOPS (SRDSW)

Abstract
On-line applications and services are now a critical part of our everyday life. Using these services typically requires us to trust our personal or company's information to a large number of third-party entities. These entities enforce several security measures to avoid unauthorized accesses but data is still stored on common database systems that are designed without data privacy concerns in mind. As a result, data is vulnerable against anyone with direct access to the database, which may be external attackers, malicious insiders, spies or even subpoenas. Building strong data privacy mechanisms on top of common database systems is possible but has a significant impact on the system's resources, computational capabilities and performance. Notably, the amount of useful computation that may be done over strongly encrypted data is close to none, which defeats the purpose of offloading computation to third-party services. In this paper, we propose to shift the need to trust in the honesty and security of service providers to simply trust that they will not collude. This is reasonable as cloud providers, being competitors, do not share data among themselves. We focus on NoSQL databases and present SafeRegions, a novel prototype of a distributed and secure NoSQL database that is built on top of HBase and that guarantees strong data privacy while still providing most of HBase's query capabilities. SafeRegions relies on secret sharing and multiparty computation techniques to provide a NoSQL database built on top of multiple, non-colluding service providers that appear as a single one to the user. Strikingly, service providers, individually, cannot disclose any of the user's data but, together, are able to offer data storage and processing capabilities. Additionally, we evaluate SafeRegions exposing performance trade-offs imposed by security mechanisms and provide useful insights for future research on performance optimization.

2016

Strain and curvature-independent temperature sensor based on an interferometer taper fabricated with a CO2 laser

Authors
Martins, TJM; Marques, MB; Frazao, O;

Publication
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS

Abstract
An optical fiber interferometer taper fabricated with a CO2 laser is proposed for strain and curvature-independent temperature measurement. Variations in temperature produce changes in the conditions of the interference between light traveling along the core and cladding and a linear behavior is verified for the relation between the wavelength of the resonant loss peak and temperature, yielding a sensitivity of 110 pm/degrees C for a range between 25 and 510 degrees C. Both the applied strain and curvature only promote significant changes in the transmitted power, leaving the wavelength of the resonant loss peak approximately constant and rendering this optical sensing device a good strain and curvature-independent temperature sensor. (c) 2016 Wiley Periodicals, Inc.

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