2010
Authors
Avila, P; Costa, L; Bastos, J; Lopes, P; Pires, A;
Publication
SISTEMAS Y TECNOLOGIAS DE INFORMACION
Abstract
The process of resources systems selection takes an important part in Distributed/Agile/Virtual Enterprises (D/A/V Es) integration. However, the resources systems selection is still a difficult matter to solve in a D/A/VE, as it is pointed out in this paper. Globally, we can say that the selection problem has been equated from different aspects, originating different kinds of models/algorithms to solve it. In order to assist the development of a web prototype tool (broker tool), intelligent and flexible, that integrates all the selection model activities and tools, and with the capacity to adequate to each D/A/V E project or instance (this is the major goal of our final project), we intend in this paper to show: a formulation of a kind of resources selection problem and the limitations of the algorithms proposed to solve it. We formulate a particular case of the problem as an integer programming, which is solved using simplex and branch and bound algorithms, and identify their performance limitations (in terms of processing time) based on simulation results. These limitations depend on the number of processing tasks and on the number of pre-selected resources per processing tasks, defining the domain of applicability of the algorithms for the problem studied. The limitations detected open the necessity of the application of other kind of algorithms (approximate solution algorithms) outside the domain of applicability founded for the algorithms simulated. However, for a broker tool it is very important the knowledge of algorithms limitations, in order to, based on problem features, develop and select the most suitable algorithm that guarantees a good performance
2010
Authors
Santos, PM; Ferreira, JC;
Publication
28th Norchip Conference, NORCHIP 2010
Abstract
This paper describes an FPGA-based system capable of computing the distance of objects in a scene to two stereo cameras, and use that information to isolate objects in the foreground. For this purpose, four disparity maps are generated in real time, according to different similarity metrics and sweep directions, and then merged into a single foreground-versus-background bitmap. Our main contribution is a custom-built hardware architecture for the disparity map calculation, and an optional post-processing stage that coarsens the output to improve resilience against spurious results. The system was described in Verilog, and a prototype implemented on a Xilinx Virtex-II Pro FPGA proved capable of processing 640x480 black-and-white images at a maximum frame rate of 40 fps, using 3x3 matching windows and detecting disparities of up to 135 pixels. ©2010 IEEE.
2010
Authors
Rodrigues, RB; Mendes, VMF; Catalao, JPS;
Publication
IEEE TRANSACTIONS ON POWER DELIVERY
Abstract
This paper presents an investigation into cloud-to-ground lightning activity over the continental territory of Portugal with data collected by the national Lightning Location System. The Lightning Location System in Portugal is first presented. Analyses about geographical, seasonal, and polarity distribution of cloud-to-ground lightning activity and cumulative probability of peak current are carried out. An overall ground flash density map is constructed from the database, which contains the information of more than five years and almost four million records. This map is compared with the thunderstorm days map, produced by the Portuguese Institute of Meteorology, and with the orographic map of Portugal. Finally, conclusions are duly drawn.
2010
Authors
Silva, ML; Ferreira, JC;
Publication
13TH EUROMICRO CONFERENCE ON DIGITAL SYSTEM DESIGN: ARCHITECTURES, METHODS AND TOOLS
Abstract
This paper describes and evaluates a method to generate partial FPGA configurations at run-time. The proposed technique is aimed at adaptive embedded systems that employ run-time reconfiguration to achieve high flexibility and performance. The approach is based on the availability of a library of partial bitstreams for a set of basic components. New partial configurations for circuits defined by netlists of basic components are created by merging together a default bitstream of the target area, the relocated configurations of the components, and the configurations of the switch matrices used for building the connections between the components. An implementation targeting the Virtex-II Pro platform FPGA is described. It runs on the embedded 300MHz PowerPC CPU present in the FPGA. The proof-of-concept implementation was used to create partial configurations at run-time for 20 circuits with up to 21 components and 288 connections. The complete configuration creation process took between 7s and 97 s.
2010
Authors
Catalao, JPS; Pousinho, HMI; Mendes, VMF;
Publication
IEEE LATIN AMERICA TRANSACTIONS
Abstract
This paper is on the problem of short-term hydro scheduling, particularly concerning a head-sensitive hydro chain. A novel mixed-integer nonlinear programming approach is proposed for optimizing power generation efficiency. The proposed approach considers not only the nonlinear dependence between power generation, water discharge and head, but also start-up costs for the hydro units and discontinuous operating regions, in order to obtain more realistic and feasible results. Numerical results based on one of the main Portuguese cascaded hydro systems illustrate the proficiency of the proposed approach.
2010
Authors
Grigonyte, G; Cordeiro, J; Dias, G; Moraliyski, R; Brazdil, P;
Publication
Coling 2010 - 23rd International Conference on Computational Linguistics, Proceedings of the Conference
Abstract
We describe a new unsupervised approach for synonymy discovery by aligning paraphrases in monolingual domain corpora. For that purpose, we identify phrasal terms that convey most of the concepts within domains and adapt a methodology for the automatic extraction and alignment of paraphrases to identify paraphrase casts from which valid synonyms are discovered. Results performed on two different domain corpora show that general synonyms as well as synonymic expressions can be identified with a 67.27% precision.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.