2016
Authors
Rocha Rodrigues, P; Hierro Rodriguez, A; Guerreiro, A; Jorge, P; Santos, JL; Araujo, JP; Miguel Teixeira, JM;
Publication
CHEMISTRYSELECT
Abstract
In this manuscript we present a new type of hydrogen optical metamaterial sensor based on the fabrication of Pd dendritic nanostructures. The fabrication of the sensor relies on a cheap self-assembly process based on the pulsed electrodeposition method in nanoporous alumina templates. By performing optical transmission measurements, we demonstrate how this sensor can monitor hydrogen gas concentrations at room temperature either by evaluating the rate of signal decay during the Pd hydrogen absorption (transient regime) or by measuring the total variation in signal once the system achieves the equilibrium state (stationary regime). We take into account the effects of the Pd-hydrogen phase transition and its size dependency to explain the kinetics of the hydrogen absorption and desorption in the studied samples. By using the transient detection method, the sensor is able to detect in approximately 50 s the explosive H-2(g) concentration threshold of 4% v/v at atmospheric pressure and room temperature.
2016
Authors
Teles, MD; de Sousa, JF;
Publication
DECISION SUPPORT SYSTEMS VI - ADDRESSING SUSTAINABILITY AND SOCIETAL CHALLENGES
Abstract
In this paper the authors present a meta-model aiming to support decision-makers that wish to know more about how to use systems models to cope with the integration of environmental concerns into the company strategy. This is made by using a General Morphological Analysis (GMA) to bridge the gap between Operations Research (OR) analysts, decision-makers and stake-holders, making all of them part of the problem structuring and formulation process, particularly in societal issues like the environmental ones. The novelty of this approach is two-fold: (i) there are no examples in literature of a GMA research that address a linkage between environmental practices, strategic objectives, and the integration of stakeholders in the decision-making process at the level of a company; (ii) there is no GMA that had covered all the phases of a decision-making problem (problem definition, problem analysis and problem solving) in such a context.
2016
Authors
Andre, RM; Warren Smith, SC; Becker, M; Dellith, J; Rothhardt, M; Zibaii, MI; Latifi, H; Marques, MB; Bartelt, H; Frazao, O;
Publication
OPTICS EXPRESS
Abstract
Optical fiber micro-tips are promising devices for sensing applications in small volume and difficult to access locations, such as biological and biomedical settings. The tapered fiber tips are prepared by dynamic chemical etching, reducing the size from 125 mu m to just a few mu m. Focused ion beam milling is then used to create cavity structures on the tapered fiber tips. Two different Fabry-Perot micro-cavities have been prepared and characterized: a solid silica cavity created by milling two thin slots and a gap cavity. A third multi-cavity structure is fabricated by combining the concepts of solid silica cavity and gap cavity. This micro-tip structure is analyzed using a fast Fourier transform method to demultiplex the signals of each cavity. Simultaneous measurement of temperature and external refractive index is then demonstrated, presenting sensitivities of 15.8 pm/K and -1316 nm/RIU, respectively. (C) 2016 Optical Society of America
2016
Authors
Pereira, FSF; de Amo, S; Gama, J;
Publication
DISCOVERY SCIENCE, (DS 2016)
Abstract
User preferences are fairly dynamic, since users tend to exploit a wide range of information and modify their tastes accordingly over time. Existing models and formulations are too constrained to capture the complexity of this underlying phenomenon. In this paper, we investigate the interplay between user preferences and social networks over time. We propose to analyze user preferences dynamics with his/her social network modeled as a temporal network. First, we define a temporal preference model for reasoning with preferences. Then, we use evolving centralities from temporal networks to link with preferences dynamics. Our results indicate that modeling Twitter as a temporal network is more appropriated for analyzing user preferences dynamics than using just snapshots of static network.
2016
Authors
Kolev, B; Bondiombouy, C; Levchenko, O; Valduriez, P; Jimenez, R; Pau, R; Pereira, J;
Publication
PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON CLOUD COMPUTING AND SERVICES SCIENCE, VOL 1 (CLOSER)
Abstract
The blooming of different cloud data management infrastructures has turned multistore systems to a major topic in the nowadays cloud landscape. In this paper, we give an overview of the design of a Cloud Multidatastore Query Language (CloudMdsQL), and the implementation of its query engine. CloudMdsQL is a functional SQL-like language, capable of querying multiple heterogeneous data stores (relational, NoSQL, HDFS) within a single query that can contain embedded invocations to each data store's native query interface. The major innovation is that a CloudMdsQL query can exploit the full power of local data stores, by simply allowing some local data store native queries (e.g. a breadth-first search query against a graph database) to be called as functions, and at the same time be optimized.
2016
Authors
Reis, LP; Costa, AP; de Souza, FN;
Publication
2016 11TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)
Abstract
Computer Assisted Qualitative Data Analysis Software (CAQDAS) may be defined as tools that help researchers developing qualitative research projects. These software packages help the users with tasks such as transcription analysis, writing and annotation, coding and text interpretation, recursive abstraction, content search and analysis, discourse analysis, data mapping, grounded theory methodology, among several other types of analysis. This paper surveys the most relevant CAQDAS software packages comparing their features on different areas such as data management and organization, data annotation, search and query capacities, data visualization, import/export potentialities and teamwork/collaborative work features.
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