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28 results on '"Salgado, César Marques"'

26. A novel radioactive particle tracking algorithm based on Deep Rectifier Neural Network

Author

Sophia de Freitas Dam, Roos, Carvalho dos Santos, Marcelo, Moreira do Desterro, Filipe Santana, Salgado, William Luna, Schirru, Roberto, and Salgado, César Marques

Abstract

Radioactive particle tracking (RPT) is a minimally invasive nuclear technique that tracks a radioactive particle inside a volume of interest by means of a mathematical location algorithm. During the past decades, many algorithms have been developed including ones based on artificial intelligence techniques. In this study, RPT technique is applied in a simulated test section that employs a simplified mixer filled with concrete, six scintillator detectors and a 137Cs radioactive particle emitting gamma rays of 662 keV. The test section was developed using MCNPX code, which is a mathematical code based on Monte Carlo simulation, and 3516 different radioactive particle positions (x,y,z) were simulated. Novelty of this paper is the use of a location algorithm based on a deep learning model, more specifically a 6-layers deep rectifier neural network (DRNN), in which hyperparameters were defined using a Bayesian optimization method. DRNN is a type of deep feedforward neural network that substitutes the usual sigmoid based activation functions, traditionally used in vanilla Multilayer Perceptron Networks, for rectified activation functions. Results show the great accuracy of the DRNN in a RPT tracking system. Root mean squared error for x, y and coordinates of the radioactive particle is, respectively, 0.03064, 0.02523 and 0.07653.

Published
2021
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27. Dose efetiva comprometida devida aos radionuclídeos 40K, 226Ra, 228Ra e 228Th contidos nos alimentos da dieta da população do Estado do Rio de Janeiro

Author

Lopes, José Marques, Braz, Delson, Lopes, Ricardo Tadeu, Salgado, César Marques, Ribeiro, Fernando Carlos Araújo, and Silva, Ademir Xavier da

Subjects
ENGENHARIAS [CNPQ], Detecção de radiação gama, HPGe, Dose efetiva comprometida, Ingestão anual de radionuclídeos
Abstract

Submitted by Moreno Barros (moreno@ct.ufrj.br) on 2020-10-04T00:43:59Z No. of bitstreams: 1 JoseMarquesLopes.pdf: 2748163 bytes, checksum: f823f55026a613fea675dbbb9f1f31c8 (MD5) Made available in DSpace on 2020-10-04T00:43:59Z (GMT). No. of bitstreams: 1 JoseMarquesLopes.pdf: 2748163 bytes, checksum: f823f55026a613fea675dbbb9f1f31c8 (MD5) Previous issue date: 2018-02 A dose efetiva anual devida ao consumo de radionuclídeos naturais 40K, 226Ra, 228Ra e 228Th foi estimada a partir da espectrometria gama de alta resolução, dados de consumo alimentar para os habitantes do estado do Rio de Janeiro e coeficientes de dose publicados pela ICRP 119. As amostras analisadas foram de cereais, grãos, legumes, farinhas, líquidos e perecíveis. A calibração em energia foi feita utilizando fontes puntiformes certificadas e a eficiência de detecção para cada amostra foi obtida com o programa LabSOCS. Em todas as amostras, o 40K foi o único elemento que apresentou valor de concentração específica acima da Atividade Mínima Detectável. No entanto, a maior contribuição para a dose efetiva comprometida foi devido aos radionuclídeos 226Ra e 228Ra, com 986 μSv.ano-1 e 208 μSv.ano-1 , respectivamente. Os maiores contribuintes para dose foram os líquidos e os cereais, com respectivamente, 875 μSv.ano-1 e 564 μSv.ano-1 . A dose efetiva anual total calculada foi de 1,36 mSv.ano-1 , quase 5 vezes acima do valor sugerido pela UNSCEAR. O principal contribuinte para este valor foi a concentração específica de 226Ra e 228Ra no feijão e na água, visto que estes dois radionuclídeos tem os maiores fatores de conversão para dose efetiva dentre os radionuclídeos aqui estudados, e os dois alimentos apresentam as maiores médias de consumo anual. Committed effective dose due to the consumption of natural radionuclides 40K, 226Ra, 228Ra and 228Th was estimated from the high-resolution gamma spectrometry, food consumption data for the inhabitants of Rio de Janeiro state and dose coefficients published by the ICRP 119. The analyzed samples were cereals, grains, vegetables, flours, liquids and perishables. Energy calibration was done using certified point sources and the detection efficiency for each sample was obtained from LabSOCS software. In all samples, 40K was the only element that presented specific concentration value above the MDA. However, the greatest contribution to the committed effective dose was due to 226Ra and 228Ra, with 986 μSv.y-1 and 208 μSv.y-1, respectively. The major contributors to the dose were liquids and cereals, with 875 μSv.y-1 and 564 μSv.y-1, respectively. The total committed effective dose was 1.36 mSv.y-1, almost 5- fold higher than the value suggested by UNSCEAR. The main contributor to this value was the specific concentration of 226Ra and 228Ra in bean and water measured in this work, since these two radionuclides have the largest effective dose conversion factors among the radionuclides studied here, and the two foods present the highest annual consumption averages among all the foods studied

Published
2018

28. Prediction of volume fractions in three-phase flows using nuclear technique and artificial neural network.

Author

Salgado CM, Brandão LE, Schirru R, Pereira CM, da Silva AX, and Ramos R

Abstract

This work presents methodology based on nuclear technique and artificial neural network for volume fraction predictions in annular, stratified and homogeneous oil-water-gas regimes. Using principles of gamma-ray absorption and scattering together with an appropriate geometry, comprised of three detectors and a dual-energy gamma-ray source, it was possible to obtain data, which could be adequately correlated to the volume fractions of each phase by means of neural network. The MCNP-X code was used in order to provide the training data for the network.

Published
2009
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