2014
Autores
Iria, JP; Soares, FJ; Madureira, AG; Heleno, M;
Publicação
2014 IEEE 8TH INTERNATIONAL POWER ENGINEERING AND OPTIMIZATION CONFERENCE (PEOCO)
Abstract
This paper proposes a novel method to characterize the availability of household loads to participate in demand response programmes, as well as detailed mathematical models to characterize households loads. The availability of the households results from the flexibility of their controllable loads to increase/reduce consumption. This flexibility is calculated taking into account the comfort levels predefined by the customers and the technical restrictions of the controllable loads. The proposed method was evaluated through a management algorithm developed to perform demand control actions in quasi-real-time, according to the objectives of the distribution system operator or energy aggregator and the availability of the household loads. A scenario with a single household located in a semi-urban area is used to illustrate the application of the algorithm and validate the proposed method.
2014
Autores
da Silva, JR; Castro, JA; Ribeiro, C; Lopes, JC;
Publicação
SEMANTIC WEB: ESWC 2014 SATELLITE EVENTS
Abstract
Research datasets in the so-called "long-tail of science" are easily lost after their primary use. Support for preservation, if available, is hard to fit in the research agenda. Our previous work has provided evidence that dataset creators are motivated to spend time on data description, especially if this also facilitates data exchange within a group or a project. This activity should take place early in the data generation process, when it can be regarded as an actual part of data creation. We present the first prototype of the Dendro platform, designed to help researchers use concepts from domain-specific ontologies to collaboratively describe and share datasets within their groups. Unlike existing solutions, ontologies are used at the core of the data storage and querying layer, enabling users to establish meaningful domain-specific links between data, for any domain. The platform is currently being tested with research groups from the University of Porto.
2014
Autores
Pessoa, LM; Tavares, JS; Coelho, D; Salgado, HM;
Publicação
OPTICS EXPRESS
Abstract
Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments. (C) 2014 Optical Society of America
2014
Autores
Conan, R; Correia, C;
Publicação
ADAPTIVE OPTICS SYSTEMS IV
Abstract
Object Oriented Mat lab Adaptive Optics (OOMAO) is a Mat lab toolbox dedicated to Adaptive Optics (AO) systems. OOMAO is based on a small set of classes representing the source, atmosphere, telescope, wavefront sensor, Deformable Mirror (DM) and an imager of an AO system. This simple set of classes allows simulating Natural Guide Star (NGS) and Laser Guide Star (LGS) Single Conjugate AO (SCAO) and tomography AO systems on telescopes up to the size of the Extremely Large Telescopes (ELT). The discrete phase screens that make the atmosphere model can be of infinite size, useful for modeling system performance on large time scales. OOMAO comes with its own parametric influence function model to emulate different types of DMs. The cone effect, altitude thickness and intensity profile of LGSs are also reproduced. Both modal and zonal modeling approach are implemented. OOMAO has also an extensive library of theoretical expressions to evaluate the statistical properties of turbulence wavefronts. The main design characteristics of the OOMAO toolbox are object oriented modularity, vectorized code and transparent parallel computing. OOMAO has been used to simulate and to design the Multi Object AO prototype Raven at the Subaru telescope and the Laser Tomography AO system of the Giant Magellan Telescope. In this paper, a Laser Tomography AO system on an ELT is simulated with OOMAO. In the first part, we set up the class parameters and we link the instantiated objects to create the source optical path. Then we build the tomographic reconstructor and write the script for the pseudo-open-loop controller.
2014
Autores
Marques, L; Vasconcelos, V; Pedreiras, P; Silva, V; Almeida, L;
Publicação
2014 IEEE EMERGING TECHNOLOGY AND FACTORY AUTOMATION (ETFA)
Abstract
In safety-critical systems a global high-reliability is sought, including in the communication network when a distributed control system is used. The FlexRay protocol was developed within the automotive industry with the necessary characteristics to respond to the demands of safety-critical applications, e.g. X-by-wire. Nevertheless, the FlexRay protocol does not define a mechanism to guarantee message delivery, nor defines global error signaling, leaving the resolution of these problems to the application. This paper presents a preliminary proposal for a mechanism that uses temporal redundancy to recover transient errors in time-triggered messages. An extra node is used to trigger message retransmissions whenever errors or omissions do effectively occur. This mechanism uses the FlexRay dynamic segment to implement message retransmissions, leading to a minimum recovery time, typically one cycle, together with a very small bandwidth usage.
2014
Autores
Branco, MC; Delgado, C; Sa, M; Sousa, C;
Publicação
BALTIC JOURNAL OF MANAGEMENT
Abstract
Purpose - This study investigates the use of the internet by the largest companies based in Sweden and Spain to communicate their engagement in corporate social responsibility (CSR) activities. Its purpose is to analyse to what extent, if any, are there differences in the CSR communication on the web sites companies from these two countries. Design/methodology/approach - The paper examines CSR communication on the internet by companies based in Sweden and Spain. Non-parametric statistics are used to analyse some factors that influence disclosure, namely country, industry affiliation, profitability, and size. Findings - Findings suggest that in spite of the existence of a high degree of similarity between CSR communication practices, companies from Spain place social responsibility information in more prominent sections and devote more space to said information. Swedish companies are found to disclose more their codes of conduct/ethics and CSR-related press clips and published articles. Research limitations/implications - The sample is small. There may be content analysis issues associated with subjectivity in the coding process. Originality/value - It adds to the scarce research on CSR communication by companies in these countries by providing new empirical data and extends prior research comparing such practices in different international models of CSR.
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