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Publications

2017

Mitigation in the Very Short-term of Risk from Wind Ramps with Unforeseen Severity

Authors
Pinto, M; Miranda, V; Saavedra, O; Carvalho, L; Sumaili, J;

Publication
JOURNAL OF CONTROL AUTOMATION AND ELECTRICAL SYSTEMS

Abstract
This paper addresses a critical analysis of the impact of the wind ramp events with unforeseen magnitude in power systems at the very short term, modeling the response of the operational reserve against this type of phenomenon. A multi-objective approach is adopted, and the properties of the Pareto-optimal fronts are analyzed in cost versus risk, represented by a worst scenario of load curtailment. To complete this critical analysis, a study about the usage of the reserve in the event of wind power ramps is performed. A case study is used to compare the numerical results of the models based on stochastic programming and models that take a risk analysis view in the system with high level of wind power. Wind power uncertainty is represented by scenarios qualified by probabilities. The results show that the reliability reserve may not be adequate to accommodate unforeseen wind ramps and therefore the system may be at risk.

2017

Entrepreneurship and national culture: How cultural differences among countries explain entrepreneurial activity

Authors
Dantas, JGL; Moreira, AC; Valente, FM;

Publication
Entrepreneurship: Concepts, Methodologies, Tools, and Applications

Abstract
The direct relationship between national cultural practice and entrepreneurship activities is analyzed in this chapter, based on the analysis of 44 countries. Datasets from 2012 and 2013 Global Entrepreneurship Monitor (GEM) report are used to characterize three types of entrepreneurship: Early-stage entrepreneurial activity (TEA); necessity-driven entrepreneurship (NDE) and opportunity-driven (ODE) entrepreneurship. Data sets on national cultural values are used to analyze five dimensions of Hofstede's work on cultural values (power distance, individualism/collectivism, masculinity/femininity, long/short term orientation, and uncertainty avoidance). For that, the authors use the Values Survey Module 2013, which has been adapted from Hofstede 's previous work from 2010 and 2008. The main conclusion is that the three types of entrepreneurship analyzed in this chapter are differently explained by the cultural and expanded models. If the country of origin and the type of economy are useful to explain TEA, they are of no added value to explain necessity-driven or opportunity-driven entrepreneurship.

2017

Combining Process Based Monitoring with Multi-layer Stream Mapping

Authors
Fisseler, D; Schneider, A; Lourenco, EJ; Baptista, AJ;

Publication
SUSTAINABLE DESIGN AND MANUFACTURING 2017

Abstract
For a company it is important to improve resource and eco-efficiency in order to save money, the environment and to improve the company's image. We present a new approach combining Multi-layer Stream Mapping (MSM) and a Business Process Based Monitoring and Control Framework to monitor relevant process variables and use the values as an input for MSM to reduce waste and costs. This combination supports the decision making process and allows to identify major inefficiencies and provides means for more sustainability.

2017

VirtualSign Game Evaluation

Authors
Escudeiro, P; Escudeiro, N; Norberto, M; Lopes, J;

Publication
SERIOUS GAMES, INTERACTION AND SIMULATION

Abstract
This paper presents the evaluation methods and techniques applied to the serious game developed within the VirtualSign project as well as the results achieved through those methods. VirtualSign is a Portuguese sign language bi-directional translator with three main components. The components are a gesture to text translator, a text to gesture translator and a serious game. The serious game aims to make the process of learning sign language easier and enjoyable using the VirtualSign bi-directional translator. The method used to evaluate the VirtualSign was the Quantitative Evaluation Framework (QEF). The translator undertakes a rigid validation process by both sign language experts and the deaf community. The evaluation process was also supported by questionnaires. The precision of the translator has a direct impact on the game performance. To evaluate the precision of the automatic translator we have used QEF and 10-fold cross validation to estimate the accuracy of the translator. The experimental results show a precision above 90%. In the identification of the Portuguese Sign Language terms As for the game the quality rate is 88% based on the QEF evaluation.

2017

On the rate of decrease in logical depth

Authors
Antunes, LF; Souto, A; Vitanyi, PMB;

Publication
THEORETICAL COMPUTER SCIENCE

Abstract
The logical depth with significance b of a string x is the shortest running time of a program for x that can be compressed by at most b bits. Another definition is based on algorithmic probability. We give a simple new proof for the known relation between the two definitions. We also prove the following: Given a string we can consider the maximal decrease in logical depth when the significance parameter increases by 1. There exists a sequence of strings of lengths n = 1,2,..., such that this maximal decrease as a function of n rises faster than any computable function but not as fast as the Busy Beaver function. This holds also for the computation times of the shortest programs of these strings.

2017

Design and dynamic modelling of an ankle-foot prosthesis for humanoid robot

Authors
Alves, Joana; Seabra, Eurico; Ferreira, Cesar; Santos, CristinaP.; Reis, LuisPaulo;

Publication
2017 IEEE International Conference on Autonomous Robot Systems and Competitions, ICARSC 2017, Coimbra, Portugal, April 26-28, 2017

Abstract

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