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Publicações

2015

Interaction Paradigms Versus Age-Related User Profiles: an Evaluation on Content Selection

Autores
Carvalho, DCM; Bessa, MEC; Magalhaes, LGM; Carrapatoso, EMEM;

Publicação
IEEE LATIN AMERICA TRANSACTIONS

Abstract
Novel input modalities such as touch, tangibles or gestures try to exploit human's innate skills rather than imposing new learning processes. However, despite the recent boom of different natural interaction paradigms, it hasn't been systematically evaluated how these interfaces influence a user's performance or whether each interface could be more or less appropriate when it comes to: 1) different age groups; and 2) different basic operations, as data selection, insertion or manipulation. This work presents the first step of an exploratory evaluation about whether or not the users' performance is indeed influenced by the different interfaces. The key point is to understand how different interaction paradigms affect specific target-audiences (children, adults and older adults) when dealing with a selection task. 60 participants took part in this study to assess how different interfaces may influence the interaction of specific groups of users with regard to their age. Four input modalities were used to perform a selection task and the methodology was based on usability testing (speed, accuracy and user preference). The study suggests a statistically significant difference between mean selection times for each group of users, and also raises new issues regarding the "old" mouse input versus the "new" input modalities.

2015

Impact of the future water value on wind-reversible hydro offering strategies in electricity markets

Autores
de la Nieta, AAS; Contreras, J; Cataldao, JPS;

Publicação
ENERGY CONVERSION AND MANAGEMENT

Abstract
A coordinated offering strategy between a wind farm and a reversible hydro plant can reduce wind power imbalances, improving the system efficiency whilst decreasing the total imbalances. A stochastic mixed integer linear model is proposed to maximize the profit and the future water value FWV of the system using Conditional Value at Risk (CVaR) for risk-hedging. The offer strategies analyzed are: (i) single wind-reversible hydro offer with a physical connection between wind and hydro units to store spare wind energy, and (ii) separate wind and reversible hydro offers without a physical connection between them. The effect of considering the FWV of the reservoirs is studied for several time horizons: one week (168 h) and one month (720 h) using an illustrative case study. Conclusions are duly drawn from the case study to show the impact of FWV in the results.

2015

Stable Integration of Power Electronics-Based DG Links to the Utility Grid with Interfacing Impedance Uncertainties

Autores
Hoseini, SK; Pouresmaeil, E; Adabi, J; Catalao, JPS;

Publicação
TECHNOLOGICAL INNOVATION FOR CLOUD-BASED ENGINEERING SYSTEMS

Abstract
For the integration of distributed generation (DG) units to the utility grid, voltage source converter (VSC) is the key technology. In order to realize high quality power injection, different control techniques have been adopted. However, the converter-based DG interface is subject to inevitable uncertainties, which adversely influence the performance of the controller. The interfacing impedance seen by the VSC may considerably vary in real distribution networks. It can be observed that the stability of the DG interface is highly sensitive to the impacts of interfacing impedance changes so that the controller cannot inject appropriate currents. To deal with the instability problem, this paper proposes an enhanced fractional order active sliding mode control scheme for integration of DG units to the utility grid, which is much less sensitive to interfacing impedance variations. A fractional sliding surface which demonstrates the desired dynamics of the system is developed and then the controller is designed in two phases: sliding phase and reaching phase to keep the control loop stable. The proposed controller takes a role to provide high quality power injection and ensures precise current tracking and fast response despite uncertainties. Theoretical analyses and simulation results are verified to study the performance and feasibility of the proposed control scheme.

2015

18th IEEE International Conference on Computational Science and Engineering, CSE 2015, Porto, Portugal, October 21-23, 2015

Autores
Plessl, C; Baz, DE; Cong, G; Cardoso, JMP; Veiga, L; Rauber, T;

Publicação
CSE

Abstract

2015

Cryogenic Temperature Response of Reflection-Based Phase-Shifted Long-Period Fiber Gratings

Autores
Martins, R; Caldas, P; Teixeira, B; Azevedo, J; Monteiro, J; Belo, JH; Araujo, JP; Santos, JL; Rego, G;

Publicação
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
In this study, we investigated the temperature behavior of phase-shifted long-period fiber gratings (PS-LPFGs) inscribed in two types of optical fiber: B/Ge and SMF28. The experiments were carried out from 5 to 305 K using a superconducting quantum interference device magnetometer. The average temperature sensitivity obtained of -0.43 nm/K for PS-LPFGs inscribed in the B/Ge fiber is one order of magnitude larger than for PS-LPFGs inscribed in the SMF28 fiber, in the 60-240 K range. Values ranging from -0.08 nm/K up to 0.2 nm/K were obtained in the 5-35 K temperature range, which are considerably better than previous results achieved for metal-coated FBGs and also for LPFGs inscribed in a similar B/Ge codoped fiber. Nevertheless, further work is required in order to correctly address sensor reliability.

2015

Present and future languages – How innovation has changed us

Autores
Au Yong Oliveira, M; Moutinho, R; Ferreira, JJP; Ramos, AL;

Publicação
Journal of Technology Management and Innovation

Abstract
Given the growth in usage of online social networks, such as Facebook, YouTube, Instagram and Snapchat, which rely on videos and images (such as photos) to relay information between connections, new intuitive languages, though not yet formally recognized, have emerged. We also herein give the example of a new language we have created – the Business Narrative Modelling Language (BNML) – which communicates business perspectives based on pictorial representations, supported by the narrative. Currently, the concept of language is linked to the use of words. We foresee that such a definition of language will have to change to include other structured forms of communication, resorting and relying on graphics, also. We give examples of BNML representations, with regards to two case studies we have performed, based on face-to-face interviews and company visits. At ExpressGlass technology plays an important role, while at Yazaki Saltano a remarkable team effort between Toyota suppliers is made evident, to create innovation. © Universidad Alberto Hurtado, Facultad de Economía y Negocios.

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