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Publications

2017

Organization-Based Multi-agent System of Local Electricity Market: Bottom-Up Approach

Authors
Gazafroudi, AS; Castrillo, FP; Pinto, T; Corchado, JM;

Publication
PAAMS (Special Sessions)

Abstract
This work proposes a organization-based Multi-Agent System that models Local Electricity Market (MASLEM). A bottom-up approach is implemented to manage energy in this work. In this context, agents are able to connect to each other and the power grid to transact electrical energy, and manage their inside electrical energy independently. A Demand Response Program (DRP) based on Indirect Load Control (ILC) method is also used. The performance of our work is evaluated through an Agent Based Modeling (ABM) implementation.

2017

Optimal control for an irrigation problem with several fields and common reservoir

Authors
Lopes, SO; Fontes, FACC;

Publication
Lecture Notes in Electrical Engineering

Abstract
In a previous study, the authors developed the planning of the water used in the irrigation systems of a given farmland in order to ensure that the field cultivation is in a good state of preservation. In this paper, we introduce a model to minimize the water flowing into a reservoir that supplies different fields with different types of crops. This model is described as an optimal control problem where the water flow from a tap and the water used in the fields are the controls. The trajectories are described as the humidity in the soil and the amount of water in the reservoir. © Springer International Publishing Switzerland 2017.

2017

Design and evaluation of a novel out-of-reach selection technique for VR using iterative refinement

Authors
Mendes, D; Medeiros, D; Sousa, M; Cordeiro, E; Ferreira, A; Jorge, JA;

Publication
COMPUTERS & GRAPHICS-UK

Abstract
In interactive systems, the ability to select virtual objects is essential. In immersive virtual environments, object selection is usually done at arm's length in mid-air by directly intersecting the desired object with the user's hand. However, selecting objects outside user's arm-reach still poses significant challenges, which direct approaches fail to address. Techniques proposed to overcome such limitations often follow an arm-extension metaphor or favor selection volumes combined with ray-casting. Nonetheless, while these approaches work for room sized environments, they hardly scale up to larger scenarios with many objects. In this paper, we introduce a new taxonomy to classify existing selection techniques. In its wake, we propose PRECIOUS, a novel mid-air technique for selecting out-of-reach objects, featuring iterative refinement in Virtual Reality, an hitherto untried approach in this context. While comparable techniques have been developed for non-stereo and non-immersive environments, these are not suitable to Immersive Virtual Reality. Our technique is the first to employ an iterative progressive refinement in such settings. It uses cone-casting to select multiple objects and moves the user closer to them in each refinement step, to allow accurate selection of the desired target. A user evaluation showed that PRECIOUS compares favorably against state-of-the-art approaches. Indeed, our results indicate that PRECIOUS is a versatile approach to out-of-reach target acquisition, combining accurate selection with consistent task completion times across different scenarios.

2017

Function-based modulation control for modular multilevel converters under varying loading and parameters conditions

Authors
Mehrasa, M; Pouresmaeil, E; Akorede, MF; Zabihi, S; Catalao, JPS;

Publication
IET GENERATION TRANSMISSION & DISTRIBUTION

Abstract
This study presents a new function-based modulation control technique for modular multilevel converters (MMCs). The main contribution of this study is the formulation of two new modulation functions for the required switching signals of the MMC's upper and lower sub-modules, respectively. The output and circulating current equations of the converter are employed to attain the arm's currents which are utilised for the proposed modulation functions, which have two important features: (i) it is much less complex compared to the existing control methods of MMC; and (ii) the proposed controller can be regulated properly to deal with parameter variations in a bid to ensure stable and accurate performance. In this controller, the MMC output current magnitude and phase angle required for special active and reactive power sharing can be easily applied to the modulation functions. Also, the equivalent capacitors of upper and lower sub-modules are discussed based on the proposed modulation functions. Finally, simulations are performed in Matlab/Simulink environment to evaluate the performance of the proposed control technique in both the dynamic conditions of load as well as varying parameters.

2017

Foreword to the special issue of the 18th IEEE international conference on computational science and engineering (CSE2015)

Authors
Plessl, C; Cong, GJ; Cardoso, JMP;

Publication
CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE

Abstract

2017

A Review Between Consumer and Medical-Grade Biofeedback Devices for Quality of Life Studies

Authors
Nogueira, P; Urbano, J; Reis, LP; Cardoso, HL; Silva, D; Rocha, AP;

Publication
RECENT ADVANCES IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 2

Abstract
With the rise in wearable technology and "health culture", we are seeing a rising interest and affordances in studying how to not only prolong life expectancy but also in how to improve individuals' quality of life. On one hand, this attempts to give meaning to the increasing life expectancy, as living above a certain threshold of pain and lack of autonomy or mobility is both degrading and unfair. On the other hand, it lowers the cost of continuous care, as individuals with high quality of life indexes tend to have lower hospital readmissions or secondary complications, not to mention higher physical and mental health. In this paper, we evaluate the current state of the art in physiological therapy (biofeedback) along with the existing medical grade and consumer grade hardware for physiological research. We provide a comparative analysis between these two device grades and also discuss the finer details of each consumer grade device in terms of functionality and adaptability for controlled (laboratory) and uncontrolled (field) studies.

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