PAULO HENRIQUE FERRAZ MASOTTI
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Artigo IPEN-doc 24758 Classification of natural circulation two-phase flow image patterns based on self-organizing maps of full frame DCT coefficients2018 - MESQUITA, ROBERTO N. de; CASTRO, LEONARDO F.; TORRES, WALMIR M.; ROCHA, MARCELO da S.; UMBEHAUN, PEDRO E.; ANDRADE, DELVONEI A.; SABUNDJIAN, GAIANE; MASOTTI, PAULO H.F.Many of the recent nuclear power plant projects use natural circulation as heat removal mechanism. The accuracy of heat transfer parameters estimation has been improved through models that require precise prediction of two-phase flow pattern transitions. Image patterns of natural circulation instabilities were used to construct an automated classification system based on Self-Organizing Maps (SOMs). The system is used to investigate the more appropriate image features to obtain classification success. An efficient automated classification system based on image features can enable better and faster experimental procedures on two-phase flow phenomena studies. A comparison with a previous fuzzy inference study was foreseen to obtain classification power improvements. In the present work, frequency domain image features were used to characterize three different natural circulation two-phase flow instability stages to serve as input to a SOM clustering algorithm. Full-Frame Discrete Cosine Transform (FFDCT) coefficients were obtained for 32 image samples for each instability stage and were organized as input database for SOM training. A systematic training/test methodology was used to verify the classification method. Image database was obtained from two-phase flow experiments performed on the Natural Circulation Facility (NCF) at Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN), Brazil. A mean right classification rate of 88.75% was obtained for SOMs trained with 50% of database. A mean right classificationrate of 93.98% was obtained for SOMs trained with 75% of data. These mean rates were obtained through 1000 different randomly sampled training data. FFDCT proved to be a very efficient and compact image feature to improve image-based classification systems. Fuzzy inference showed to be more flexible and able to adapt to simpler statistical features from only one image profile. FFDCT features resulted in more precise results when applied to a SOM neural network, though had to be applied to the full original grayscale matrix for all flow images to be classified.Artigo IPEN-doc 19812 The behavior of ANGRA 2 nuclear power plant core for a small break LOCA simulated with RELAP5 code2013 - SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A.; BELCHIOR JUNIOR, ANTONIO; ROCHA, MARCELO da S.; CONTI, THADEU N.; TORRES, WALMIR M.; MACEDO, LUIZ A.; UMBEHAUN, PEDRO E.; MESQUITA, ROBERTO N.; MASOTTI, PAULO H.F.; LIMA, ANA C. de S.Artigo IPEN-doc 15277 Thermal hydraulic phenomenology for the heating process in a natural circulation facility2009 - TORRES, WALMIR M.; MACEDO, LUIZ A.; MESQUITA, ROBERTO N.; MASOTTI, PAULO H.F.; LIBARDI, ROSANI M.P.; SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A.; UMBEHAUN, PEDRO E.; CONTI, THADEU N.; FILHO, MAURO F.S.; MELO, GABRIEL R.Artigo IPEN-doc 15276 Comparison between experimental data and numerical modeling for the natural circulation phenomenon2009 - SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A.; UMBEHAUN, PEDRO E.; TORRES, WALMIR M.; MACEDO, LUIZ A.; CONTI, THADEU N.; MESQUITA, ROBERTO N.; MASOTTI, PAULO H.F.; PENHA, ROSANI M.L.; SILVA FILHO, MAURO F.; MELO, GABRIEL R.; BRAZ FILHO, FRANCISCO A.; BORGES, EDUARDO M.Artigo IPEN-doc 17037 Frequency analysis for the thermal hydraulic characterization of a natural circulation circuit2011 - TORRES, WALMIR M.; MACEDO, LUIZ A.; SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A.; UMBEHAUN, PEDRO E.; CONTI, THADEU N.; MESQUITA, ROBERTO N.; MASOTTI, PAULO H.; ANGELO, GABRIELArtigo IPEN-doc 16918 A RELAP5 study to identify flow regime in natural circulation phenomenon2011 - SABUNDJIAN, GAIANE; TORRES, WALMIR M.; MACEDO, LUIZ A.; MESQUITA, ROBERTO N.; ANDRADE, DELVONEI A.; UMBEHAUN, PEDRO E.; CONTI, THADEU N.; MASOTTI, PAULO H.F.; BELCHIOR JUNIOR, ANTONIO; ANGELO, GABRIELArtigo IPEN-doc 16868 Development of a labview web-based simulator for RELAP52011 - MACEDO, LUIZ A.; TORRES, WALMIR M.; SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A.; BELCHIOR JUNIOR, ANTONIO; UMBEHAUN, PEDRO E.; CONTI, THADEU N.; MESQUITA, ROBERTO N. de; MASOTTI, PAULO H.F.; ANGELO, GABRIELArtigo IPEN-doc 15394 Two-phase flow patterns recognition and parameters estimation through natural circulation test loop image analysis2009 - MESQUITA, R.N.; LIBARDI, R.M.P.; MASOTTI, P.H.F.; SABUNDJIAN, G.; ANDRADE, D.A.; UMBEHAUN, P.E.; TORRES, W.M.; CONTI, T.N.; MACEDO, L.A.