2014
Autores
Dionisio, R; Ribeiro, J; Marques, P; Rodriguez, J;
Publicação
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING
Abstract
This paper describes the implementation and the technical specifications of a geolocation database assisted by a spectrum-monitoring outdoor network. The geolocation database is populated according to Electronic Communications Committee (ECC) report 186 methodology. The application programming interface (API) between the sensor network and the geolocation database implements an effective and secure connection to successfully gather sensing data and sends it to the geolocation database for post-processing. On the other hand, the testbed allows authorized TV white space devices to gain access to the services of the geolocation database, according to a draft implementation of Internet Engineering Task Force (IETF) Protocol to Access White Space (PAWS) Two experimental methodologies are available with the testbed: one focused on coexistence studies with commercial wireless microphones, when the testbed is used for sensing only, and another for demonstration purposes, when the testbed is also used to emulate wireless microphone signals. Overall, this hybrid approach is a promising solution for the effective use of TV white spaces and for the coexistence with digital TV broadcast signals, or dynamic incumbent systems, such as unregistered wireless microphones.
2014
Autores
Iria, JP; Soares, FJ; Franchin, IG; Silva, N;
Publicação
2014 IEEE INTERNATIONAL ELECTRIC VEHICLE CONFERENCE (IEVC)
Abstract
This paper describes a novel Electric Vehicle (EV) charging management system which was designed to control the EV load considering simultaneously the EV owners requirements and the electrical network technical limitations. The system was developed to be integrated with existing commercial equipment for smart grids, such as distribution transformer controllers, SCADA systems and Electrical Vehicles Charging Stations. The performance of the smart charging system was evaluated using a typical Portuguese low voltage network as test case, where several EV were assumed to exist. The results obtained prove the effectiveness of the system, as it allowed charging all the EV according to their owners' preferences without increasing the network peak load or creating voltages or overload problems.
2014
Autores
Silva, E; Alvelos, F; de Carvalho, JMV;
Publicação
JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY
Abstract
The two-dimensional cutting stock problem (2DCSP) consists in the minimization of the number of plates used to cut a set of items. In industry, typically, an instance of this problem is considered at the beginning of each planning time period, what may result in solutions of poor quality, that is, excessive waste, when a set of planning periods is considered. To deal with this issue, we consider an integrated problem, in which the 2DCSP is extended from the solution in only a single production planning period to a solution in a set of production planning periods. The main difference of the approach in this work and the ones in the literature is to allow sufficiently large residual plates (leftovers) to be stored and cut in a subsequent period of the planning horizon, which may further help in the minimization of the waste. We propose two integrated integer programming models to optimize the combined two-dimensional cutting stock and lot-sizing problems, minimizing the total cost, which includes material, waste and storage costs. Two heuristics based on the industrial practice to solve the problem were also presented. Computational results for the proposed models and for the heuristics are presented and discussed.
2014
Autores
Costa, DG; Guedes, LA; Vasques, F; Portugal, P;
Publicação
2014 12TH IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS (INDIN)
Abstract
Wireless visual sensor networks can provide significant information for a large set of monitoring and surveillance applications. In these networks, mobile sinks are often used to reduce energy consumption over the network, where many algorithms have been proposed for higher energy efficiency. Frequently, visual sensors may have different relevancies for the monitoring functions of the applications, according to their potential to provide significant data. Additionally, the relevancies of visual sensors may be quickly adjusted according to the occurrence of some critical event. In such cases, higher relevant source nodes may be concurrently transmitting visual information with higher quality or frequency, potentially increasing energy consumption in intermediate nodes from those sources toward the sink. We propose an autonomous balanced positioning algorithm for mobile sinks in order to shorten the transmission paths from higher relevant sources, directly benefiting multi-hop sensor networks with multiple active visual source nodes.
2014
Autores
Pinho, LM; Moore, B; Michell, S;
Publicação
Ada-Europe
Abstract
Recently, a semantic and runtime model for parallel programming was proposed for addition to Ada. The proposal uses program annotations (expressed as Ada 2012 aspects) to inform the compiler of opportunities for parallel computation, and also offers the ability to specify details of parallel execution. The proposal includes support for specialized behaviors via dedicated libraries and a runtime environment that builds on pools of worker tasks. This paper extends that work by adding notations for data types and parallel blocks, simplifying some of the parallel notations and eliminating obstructions to the implementation of efficient parallel algorithms. © 2014 Springer International Publishing.
2014
Autores
Simoglou, CK; Kardakos, EG; Bakirtzis, EA; Chatzigiannis, DI; Vagropoulos, SI; Ntomaris, AV; Biskas, PN; Gigantidou, A; Thalassinakis, EJ; Bakirtzis, AG; Catalao, JPS;
Publicação
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
Abstract
This paper presents an overview of the different methodologies and mathematical optimization models developed in the framework of the EU-funded project SiNGULAR towards the optimal exploitation and efficient short-term operation of RES production in insular electricity networks. Specifically, the algorithms employed for the creation of system load and RES production scenarios that capture the spatial and temporal correlations of the corresponding variables as well as the procedure followed for the creation of units' availability scenarios using Monte Carlo simulation are discussed. In addition, the advanced unit commitment and economic dispatch models, that have been developed for the short-term scheduling of the conventional and RES generating units in different short-term time-scales (day-ahead, intra-day, and real-time) are presented. Indicative test results from the implementation of all models in the pilot system of the island of Crete, Greece, are illustrated and valuable conclusions are drawn.
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