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Publications

2011

A Biased Random Key Genetic Algorithm Approach for Unit Commitment Problem

Authors
Roque, LAC; Fontes, DBMM; Fontes, FACC;

Publication
EXPERIMENTAL ALGORITHMS

Abstract
A Biased Random Key Genetic Algorithm (BRKGA) is proposed to find solutions for the unit commitment problem. In this problem, one wishes to schedule energy production on a given set of thermal generation units in order to meet energy demands at minimum cost, while satisfying a set of technological and spinning reserve constraints. In the BRKGA, solutions are encoded by using random keys, which are represented as vectors of real numbers in the interval [0, 1]. The GA proposed is a variant of the random key genetic algorithm, since bias is introduced in the parent selection procedure, as well as in the crossover strategy. Tests have been performed on benchmark large-scale power systems of up to 100 units for a 24 hours period. The results obtained have shown the proposed methodology to be an effective and efficient tool for finding solutions to large-scale unit commitment problems. Furthermore, from the comparisons made it can be concluded that the results produced improve upon some of the best known solutions.

2011

Assemblathon 1: A competitive assessment of de novo short read assembly methods

Authors
Earl, D; Bradnam, K; St John, J; Darling, A; Lin, DW; Fass, J; Hung, OKY; Buffalo, V; Zerbino, DR; Diekhans, M; Nguyen, N; Ariyaratne, PN; Sung, WK; Ning, ZM; Haimel, M; Simpson, JT; Fonseca, NA; Birol, I; Docking, TR; Ho, IY; Rokhsar, DS; Chikhi, R; Lavenier, D; Chapuis, G; Naquin, D; Maillet, N; Schatz, MC; Kelley, DR; Phillippy, AM; Koren, S; Yang, SP; Wu, W; Chou, WC; Srivastava, A; Shaw, TI; Ruby, JG; Skewes Cox, P; Betegon, M; Dimon, MT; Solovyev, V; Seledtsov, I; Kosarev, P; Vorobyev, D; Ramirez Gonzalez, R; Leggett, R; MacLean, D; Xia, FF; Luo, RB; Li, ZY; Xie, YL; Liu, BH; Gnerre, S; MacCallum, I; Przybylski, D; Ribeiro, FJ; Yin, SY; Sharpe, T; Hall, G; Kersey, PJ; Durbin, R; Jackman, SD; Chapman, JA; Huang, XQ; DeRisi, JL; Caccamo, M; Li, YR; Jaffe, DB; Green, RE; Haussler, D; Korf, I; Paten, B;

Publication
GENOME RESEARCH

Abstract
Low-cost short read sequencing technology has revolutionized genomics, though it is only just becoming practical for the high-quality de novo assembly of a novel large genome. We describe the Assemblathon 1 competition, which aimed to comprehensively assess the state of the art in de novo assembly methods when applied to current sequencing technologies. In a collaborative effort, teams were asked to assemble a simulated Illumina HiSeq data set of an unknown, simulated diploid genome. A total of 41 assemblies from 17 different groups were received. Novel haplotype aware assessments of coverage, contiguity, structure, base calling, and copy number were made. We establish that within this benchmark: ( 1) It is possible to assemble the genome to a high level of coverage and accuracy, and that ( 2) large differences exist between the assemblies, suggesting room for further improvements in current methods. The simulated benchmark, including the correct answer, the assemblies, and the code that was used to evaluate the assemblies is now public and freely available from http://www.assemblathon.org/.

2011

Optical Fibre Hydrogen Sensors Based on Palladium Coatings

Authors
Coelho, L; Silva, SFO; Tafulo, PAR; Santos, JL; Frazao, O; Malcata, FX;

Publication
INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
Optical fibre sensors for Hydrogen detection at low concentrations has become a growing research area using Palladium as an active medium. Palladium is widely used in hydrogen sensing as it show a high and selective affinity for hydrogen. This metal is capable to absorb hydrogen up to 900 times its own volume which permits that during the expansion mechanical forces are applied in the fibre modifying the optical response. Several optical fibre hydrogen sensor heads coated with Palladium are presented and compared using different working principles: interferometric, intensity and fiber grating-based sensors. These principles were applied in Fabry-Perot cavities, fibre Bragg gratings written in fibre SMF28 with etching in the cladding, multimode interferometers and fibre end micro-mirrors. Palladium thin film coatings over the fibre surface and with thicknesses from 10nm to 350nm were produced by using the sputtering RF technique. These studies were performed in a Hydrogen/Nitrogen atmosphere with Hydrogen concentrations from 0% to 4% (lower limit explosion). The Bragg grating inscribed in a fibre with reduced cladding diameter appears to be one of the best approaches for a fibre optic sensing head for Hydrogen detection. Future work will continue the investigation of other fibre optic structures with Hydrogen sensing capabilities and their application in specific field situations will be assessed.

2011

Optimization Approach to a Simulation Algorithm of a Mixer-Settler System in the Transient State

Authors
Gomes, EF; Pinto, GA;

Publication
DYNAMICS, GAMES AND SCIENCE II

Abstract
In this paper we describe a parameter optimization approach to a simulation algorithm of a mixer-settler system in the transient state. The model we are using for the shallow-layer settler, in a mixer-settler system, is able to describe the hydrodynamic phenomena of the transient state of a liquid liquid system. Its mathematical model includes parameters of the drop transport process as well as of the drop drop and drop-interface coalescence with the active interface. The most adequate values of these parameters are unknown. In order to tune the model parameters we have Linked the mixer-settler simulation algorithm to an optimization procedure. We have used the Hooke-Jeeves optimization algorithm to fit these parameters to given experimental results.

2011

A SIMULATION STUDY OF A MUILTI-SITE PRODUCTION PLANT USING ARENA

Authors
Brito, AC; de Oliveira, CB; Marques, PS;

Publication
EUROPEAN SIMULATION AND MODELLING CONFERENCE 2011

Abstract
The evolution in demand is leading industry market to seek for product orders in smaller lots and shorter deadlines. A need therefore arises to adapt industry production to these market changes. A portuguese plumbing and bath accessories company decided to study a new organization layout for its multi-site production plant. The objective was to evaluate different organization scenarios in order to rationalize the floor layout and reduce costs. This Paper presents a study to evaluate different scenarios for a multi-site production plant using the Arena simulation software tool. The simulation model uses VBA (Visual Basic for Applications) to dynamically generate the simulation model. The product data is read from Excel spreadsheets or text files. Autocad is used for defining the plant layout and generating the working center coordinates. The Autocad drawing is used as the simulation background allowing the display of a realistic scaled animation.

2011

Assessment of weekly food variety of consumption by two different instruments in Portuguese elderly

Authors
de Morais, C; Afonso, C; Oliveira, B; de Almeida, MV;

Publication
ANNALS OF NUTRITION AND METABOLISM

Abstract

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