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Publications

2017

Statistical Analysis of the Influence of Several Factors on Compressive Strength of Alkali Activated Fly Ash

Authors
Cerveira, A; Correia, E; Cristelo, N; Miranda, T; Castro, F; Fernandez Jimenez, A;

Publication
2ND INTERNATIONAL CONFERENCE ON STRUCTURAL INTEGRITY, ICSI 2017

Abstract
The use of industrial by-products to produce new types of cement-substitute binders is gaining significant momentum, especially through the alkaline activation technique. However, the exact curing conditions that should be considered with each binder variation have not yet been fully understood. The aim of the present work is thus the statistical analysis of the effects of several factors, namely filler/precursor ratio and curing humidity, on the compressive strength of different mixtures prepared with mine tailings (filler), fly ash (precursor) and an alkali activator based on sodium hydroxide. Five different types of mixture were prepared, with filler/precursor ratios of 80/20, 60/40, 40/60, 20/80 and 0/100. All the specimens were cured at 80 degrees C for 7 days, after which they were submitted to a uniaxial compression strength (UCS) test. Three different values of curing humidity were considered, namely 25%, 50% and 75%. Each UCS value was the average of 9 different specimens tested. The aim of the present research is to establish how much these two factors (inert/precursor ratio and curing humidity) influence the UCS. For that purpose, a two-way Analysis of Variance (ANOVA), with interaction, was performed; followed by a Tuckey's Post hoc test. The results showed statistically significant differences for at least one humidity value F(2,127) = 31.647 (p<0.001) as well as one inert/precursor ratio F(4,127) = 371.64; (p<0.001) and for interaction F(8,127) = 9.33; (p<0.001). To evaluate which level or levels are different a Tuckey's Post hoc test was performed. This test revealed that the humidity value of 50% presented statistically significant differences regarding the remaining two values. In addition, it was concluded that this humidity value (50%) leads to lower binder's resistance. Concerning the inert/precursor ratio, the nonsignificant differences only occur between the 80/20 and 60/40 cases, although the strength values increase, in general, as the ash percentage increases. (C) 2017 The Authors. Published by Elsevier B.V.

2017

A More Intelligent Test Case Generation Approach through Task Models Manipulation

Authors
Campos, JC; Fayollas, C; Gonçalves, M; Martinie, C; Navarre, D; Palanque, PA; Pinto, M;

Publication
PACMHCI

Abstract
Ensuring that an interactive application allows users to perform their activities and reach their goals is critical to the overall usability of the interactive application. Indeed, the effectiveness factor of usability directly refers to this capability. Assessing effectiveness is a real challenge for usability testing as usability tests only cover a very limited number of tasks and activities. This paper proposes an approach towards automated testing of effectiveness of interactive applications. To this end we resort to two main elements: An exhaustive description of users’ activities and goals using task models, and the generation of scenarios (from the task models) to be tested over the application. However, the number of scenarios can be very high (beyond the computing capabilities of machines) and we might end up testing multiple similar scenarios. In order to overcome these problems, we propose strategies based on task models manipulations (e.g., manipulating task nodes, operator nodes, information...) resulting in a more intelligent test case generation approach. For each strategy, we investigate its relevance (both in terms of test case generation and in terms of validity compared to the original task models) and we illustrate it with a small example. Finally, the proposed strategies are applied on a real-size case study demonstrating their relevance and validity to test interactive applications. © 2017 Association for Computing Machinery.

2017

NOOA: Maintaining Cultural Identity Through Intergenerational Storytelling and Digital Affinity Spaces

Authors
Monteiro, J; Morais, C; Carvalhais, M;

Publication
INTERACTIVE STORYTELLING, ICIDS 2017

Abstract
The possibility to preserve perspectives of reality with spontaneous creations allowed by the web tools that now empower common users with content production skills highlights the numerous opportunities for the present and future of cultural identity maintenance. Our research approaches digital storytelling during intergenerational dynamics as a stage for a participatory contribution to the maintenance of cultural identity. With an ethnographic approach and with partnerships with existing senior movements, we seek to (a) understand the storytelling processes during intergenerational dynamics, (b) develop a framework for the participative creation of narratives in the context of intergenerational cultural identity maintenance, (c) support the participatory maintenance of cultural identity through a set of workshops for intergenerational storytelling, (d) understand the challenges and opportunities promoted by digital affinity spaces for the maintenance of cultural identity. Our contribution proposes to develop the understanding of the role that interactive narratives can have in the context of cultural identity maintenance, by developing new usage strategies to enhance cultural mediation through social and ubiquitous storytelling strategies.

2017

ARFIMA-GARCH modeling of HRV: Clinical application in acute brain injury

Authors
Almeida, R; Dias, C; Silva, ME; Rocha, AP;

Publication
Complexity and Nonlinearity in Cardiovascular Signals

Abstract
In the last decade, several HRV based novel methodologies for describing and assessing heart rate dynamics have been proposed in the literature with the aim of risk assessment. Such methodologies attempt to describe the non-linear and complex characteristics of HRV, and hereby the focus is in two of these characteristics, namely long memory and heteroscedasticity with variance clustering. The ARFIMA-GARCH modeling considered here allows the quantification of long range correlations and time-varying volatility. ARFIMA-GARCH HRV analysis is integrated with multimodal brain monitoring in several acute cerebral phenomena such as intracranial hypertension, decompressive craniectomy and brain death. The results indicate that ARFIMA-GARCH modeling appears to reflect changes in Heart Rate Variability (HRV) dynamics related both with the Acute Brain Injury (ABI) and the medical treatments effects. © 2017, Springer International Publishing AG.

2017

Wideband Dipole Antennas with Parasitic Elements for Underwater Communications

Authors
Aboderin, O; Pessoa, LM; Salgado, HM;

Publication
OCEANS 2017 - ABERDEEN

Abstract
Propagation of underwater electromagnetic signals for real-time transmission and reception of data gathered during a survey mission between an Autonomous Underwater Vehicle (AUV) and underwater sensor nodes or a docking station, continues to generate a lot of interest worldwide. To this end, underwater antennas will play a significant role in ensuring good data rates and propagation distances for various underwater applications. In this paper, the performance of two dipole antennas with different parasitic elements is assessed through simulation for usage in fresh water and operating in the High Frequency (HF) band. The antennas were designed in FEKO, an electromagnetic simulation software and their performance is assessed in terms of bandwidth, directivity and antenna-to-antenna distance. The results obtained show that these antennas exhibit wide bandwidth, which is important to achieve high data rates. Experimental results of the reflection coefficient of the fabricated antenna measured in fresh water are given that agree well with the simulation results.

2017

Bulding ontologies with ontoforinfoscience methodology: A detailed approach to the activiyies of ontology development [Construindo ontologias com a metodologia ontoforinfoscience: Uma abordagem detalhada das atividades do desenvolvimento ontológico] [Construyendo ontologías con la metodología ontoforinfoscience: Un enfoque detallado de las actividades del desarrollo ontológico]

Authors
Mendonça, FM; Soares, AL;

Publication
Ciencia da Informacao

Abstract
In the use of ontologies as knowledge information systems (KOS) for purposes of representation, organization and information retrieval, one of the biggest challenges is the ontology development process, which is complex and requires specific technical knowledge of the developers. In the recent years, several methodologies have been developed to support the ontologies building, which have steps well established, but not always well detailed for developers, causing problems in the ontologies development. This paper describes a methodology for the ontologies development, called OntoForInfoScience, which has a differential the detail of the activities of the ontology development cycle, explaining more clearly technical terms, logical and philosophical issues involved in the construction of ontologies. As current practical results of OntoForInfoScience, we presented part of the content of two ontologies developed with such methodology: (i) Hemonto: a biomedical ontology on the human blood components used for hematology and hemotherapy; (ii) Ontolegis: a legal domain ontology that represents the knowledge related to Brazilian legislative information on medical law. It is concluded that the OntoForInfoScience was very useful for the construction of formal ontological representations in both domains modeled and their details allowed to help the developers in logical and philosophical questions of the process of development and in the understanding of technical concepts of ontologies.

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