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Publications

2016

HDR video on mobile devices Unlocker of new opportunities for digital business

Authors
Melo, M; Barbosa, L; Meira, C; Branco, F; Bessa, M;

Publication
2016 11TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
Prior to having available the High Dynamic Range (HDR) techniques, certain levels of luminance could only by captured by the human eye. Currently, HDR technology overcomes the limitations of conventional imaging technology (also referred as Low Dynamic Range or LDR) and allows the capture and delivery of contents that can match the dynamic range of the real world. However, the state of the art of HDR video focus mainly on conventional sized displays typical of TVs or PCs. As the usage of mobile devices for multimedia consumption is increasing considerably, there is a need for studying the impact of the viewing of HDR video on such devices. This will allow to take full advantage of HDR technology, creating a set of opportunities for the digital business as it allows, among others, the presentation of products in a much more efficient and captivating way. On this paper it is presented a study that evaluates the impact of the HDR video delivery on mobile devices and compares it with the impact of Low Dynamic Range (LDR) content. Results show that the delivery of HDR video on mobiles is possible without requiring much more resources when comparing the delivery of LDR video.

2016

Multiyear and Multi-Criteria AC Transmission Expansion Planning Model Considering Reliability and Investment Costs

Authors
Gomes, PV; Silva, JP; Saraiva, JT;

Publication
2016 13TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
One of the major concerns in Power Systems is surely related with their reliability. Long-term expansion planning studies traditionally use the well-known deterministic "N-1" contingency criterion. However, this criterion is applied based on worst-case analyses and the obtained plan may originate over-investments. Differently, probabilistic reliability approaches can incorporate different type of uncertainties that affect power systems. In this work, a long term multi-criteria AC Transmission Expansion Planning model was developed considering two objectives - the probabilistic reliability index Expected Energy Not Supplied (EENS) and the investment cost. The Pareto-Front associated with these two objectives was obtained using Genetic Algorithms and the final solution was selected using a fuzzy decision making function. This approach was applied to the IEEE 24 Bus Test System and the results ensure its robustness and efficiency.

2016

Review of Control Strategies for Lower Limb Prostheses

Authors
Ferreira, C; Reis, LP; Santos, CP;

Publication
ROBOT 2015: SECOND IBERIAN ROBOTICS CONFERENCE: ADVANCES IN ROBOTICS, VOL 2

Abstract
Each year thousands of people lose their lower limbs, mainly due to three causes: wars, accidents and vascular diseases. The development of prostheses is crucial to improve the quality of millions of people's lives by restoring their mobility. Lower limb prostheses can be divided into three major groups: passive, semi-active or variable damping and powered or intelligent. This contribution provides a literature review of the principal control strategies used in lower limb prostheses, i.e., the controllers used in energetically powered transfemoral and transtibial prostheses. We present a comparison of the presented literature review and the future trends of this important field. It is concluded that the use of bio-inspired concepts and continuous control combined with the other control approaches can be crucial in the improvement of prosthesis controllers, enhancing the quality of amputee's lives.

2016

Combined penetration of wind and solar generation with plug-in electric vehicles

Authors
Villar, J; Salas, E; Alberto Campos, A;

Publication
ENERGY ECONOMICS IBERIAN CONFERENCE, EEIC 2016

Abstract
Combining large penetration of wind and solar generation with Plug-in Electric Vehicles (PEVs) seems a promising solution for energy cost saving and emissions reduction. PEVs connected to the grid with smart charging strategies can be an effective way to integrate non-dispatchable renewable generation, smoothing the load curve, contributing to the system stability by providing regulation services, and moving unhealthy emissions away from city centers. This paper analyzes the combined penetration of PEVs, and wind and solar generation using a Unit Commitment model for the Spanish power system, providing some insight on how the penetration of these technologies affects relevant variables such as energy and reserve, thermal plants behavior (such as starts-up and shut-downs, technological energy share, generation costs or emissions) and systems costs. Results show that PEV increase total demand, but its optimal charging smooths the net demand (to be supplied by thermal units) and the final electricity prices. In addition, solar generation penetration leads to a larger net demand with more variability but with lower production costs than wind generation penetration, due to their different hourly profiles. Finally neither solar nor wind generation penetrations are totally profitable for the system with the assumptions made, since their investments costs do not compensate the production cost decrement, but grid parity is almost reached for both technologies. (C) 2016 The Authors. Published by Elsevier Ltd.

2016

The IEC 61850 in the Portuguese distribution substations: Contemporary challenges and possible solutions

Authors
Leite, H; Martins, D; Ferreira, J; Pinto, A;

Publication
IET Conference Publications

Abstract
Interoperability may be defined as the ability of intelligent electronic devices (IED's) to exchange and use information correctly. Although the IEC 61850 standards define a consistent methodology for interconnecting IEDs in substation using LAN based technologies to promote interoperability, this ability to exchange information correctly is not always achieved between different IED's from different manufactures. This paper reports the assessment of IED's, featured with IEC 61850 standards and connected to the same communication network from different manufactures. Different interoperability tests are performed and the difficulty and challenges to exchange and receive information is also reported. Possible solutions on the XML schema to generate a compliant SCL file as well as the way to scale up the standardization of the substation project is also explored and discussed in this paper.

2016

Overloading Analysis of an Industrial Client Distribution Transformer in a Portuguese Island

Authors
Godina, R; Rodrigues, EMG; Shafie khah, M; Matias, JCO; Catalao, JPS;

Publication
2016 IEEE INTERNATIONAL ENERGY CONFERENCE (ENERGYCON)

Abstract
In this paper an analysis is made of the impact of emergency loading made by several inductive loads on the thermal ageing of a distribution transformer belonging to a private industrial client. The analyzed system is a fragment of an isolated electric grid in a Portuguese Island. A transformer thermal model is used to estimate the hot-spot temperature and top-oil temperature given the load ratio. Real data are used for the main inputs of the model, i.e., private industrial client load, transformer parameters and the characteristics of the factory. Finally, a smart transformer protection method is proposed by the authors with the aim of monitoring and protecting it from similar upcoming challenges.

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