Search

Your search keyword '"Carvalho, Nelson"' showing total 396 results
Start Over Author "Carvalho, Nelson"
396 results on '"Carvalho, Nelson"'

3. Spatio-temporal regularization of global ocean waves obtained from satellite and their graphical representation

Author

Perotto, Heitor, Farina, Leandro, and Violante-Carvalho, Nelson

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

An algorithm for representing irregular satellite data obtained from advanced synthetic aperture radar (ASAR) uniformly in space and time is introduced and comparison with WAVEWATCH III model (WW3) data is carried out. Swell global data for 2007 are analysed using statistical parameters such as bias and scattering index. Satellite data showed a great spatial uniformity compared with WW3 model. Results show underestimation of swell height by the model in the tropics and at specific higher latitude regions.

Published
2020

7. In Vivo Study of the Effect of Sugarcane Bagasse Lignin Supplementation on Broiler Chicken Diet as a Step to Validate the Established Chicken Gastrointestinal Tract In Vitro Model.

Author

de Carvalho, Nelson Mota, Souza, Carla Giselly de, Costa, Célia Maria, Castro, Cláudia, Fangueiro, Joana F., Horta, Bruno, Outor-Monteiro, Divanildo, Teixeira, José, Mourão, José Luís, Pinheiro, Victor, Amaro, Ana L., Costa, Patrícia Santos, Oliveira, Catarina S. S., Pintado, Manuela Estevez, Oliveira, Diana Luazi, and Madureira, Ana Raquel

Abstract

Since the global restrictions on antibiotics in poultry systems, there has been a growing demand for natural and sustainable feed additives for disease prevention and poultry nutrition. This study evaluated the effects of incorporating sugarcane bagasse (SCB) lignin into broiler chicken diets. The performance of the chickens, including body weight, feed intake, and mortality, as well as intestinal histomorphometry, and cecum content pH, microbiota, and volatile fatty acids were assessed. In addition, we also aimed to validate an in vitro gastrointestinal tract (GIT) model developed by Carvalho et al. (2023). One hundred and eight 1-day-old Ross 308 chicks were randomly and equally divided into two groups. The first group was fed a basal diet (BD group), while the second group was fed a basal diet supplemented with 1% (w/w) SCB lignin (BD + SCB lignin group) for 36 days. The in vivo conditions of the chicken GIT were replicated in an in vitro model. In the in vivo study, SCB lignin increased cecum acetate and butyrate levels while reducing Bifidobacterium and Enterobacteriaceae, without affecting productivity (body weight, feed intake, and mortality). The in vitro assessment reflected microbiota trends observed in vivo, although without statistical significance. The divergence in organic acid production between the in vivo and in vitro conditions likely resulted from issues with inoculum preparation. This study demonstrates that SCB lignin incorporation positively influences cecal microbiota composition without impacting the animals' productivity and physiology, suggesting its potential as a functional feed additive. For a more reliable in vitro model, adjustments in inoculum preparation are necessary. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

16. The Effects of Ocean Eddy Dipoles on Opposing Swell Waves

Author

violante-carvalho, nelson, primary, de Paula, Thiago, additional, Calado, Leandro, additional, Cavaleri, Luigi, additional, Marques, Felipe, additional, Carvalho, Luiz Mariano, additional, Cordeiro, Andre luiz, additional, and Benetazzo, Alvise, additional

Published
2024
Full Text
View/download PDF

23. EXTRACTION AND EVALUATION OF MACAÚBA ALMOND OIL (Acrocomia aculeata)

Author

Viroli, Sérgio Luís Melo, primary, Rodrigues, Fernando Morais, additional, Sousa, Paula Jucá de, additional, Chávez, Davy William Hidalgo, additional, Saraiva, Wellenilson da Silva, additional, Lisboa, Matheus, additional, Carvalho, Nelson Pereira, additional, Alves, Tiago Teixeira, additional, and Viroli, Sérgio Guimarães, additional

Published
2021
Full Text
View/download PDF

30. Understanding and modelling the mechanical response of woven composites

Author

Vieira De Carvalho, Nelson, Robinson, Paul, and Pinho, Silvestre

Subjects
629.13
Abstract

The present work focuses on improving the understanding and modelling of the mechanical response of woven composites. It comprises of original experimental observations together with novel numerical and analytical developments. The experimental work focused on the investigation of damage initiation and propagation under compression. Detailed microscopy shows that damage is controlled by the individual failure of the load-aligned tows through kink-band formation. Moreover, both weave architecture/internal geometry and support provided by the adjacent layers are seen to affect damage location and morphology, suggesting that, to capture the failure mechanisms in compression, they should be explicitly modelled. Subsequently a theoretical framework to derive periodic boundary conditions for the mechanical analysis of periodic structures, using domains smaller then the unit cells, is presented. These domains, named reduced Unit Cells, lead to significant gains in efficiency, which enable the use of refined numerical/analytical models. The framework mentioned above was used to develop a detailed nonlinear numerical model of a 2D woven composite. Weave architecture was modelled explicitly and the effect of the support provided by the adjacent layers was taken into account. The constitutive response and ultimate strength values predicted numerically agree well with experimental results for both tension and compression. Additionally, the model was used to investigate the effect of the biaxial loading ratio on the failure strength. Finally, an analytical model to predict the compressive and tensile response of woven composites is presented. The load-aligned tow was modelled as an Euler-Bernoulli beam supported by an elastic foundation. The properties of the latter are fully derived from kinematic models for the deformation of the weave, providing great insight into the deformation mechanisms of woven composites. The analytical predictions agree well with both experimental and numerical results. Overall, its flexibility offers an alternative and valuable addition to detailed numerical models, particularly when performing sensitivities studies.

Published
2012
Full Text
View/download PDF

44. EFEITO DA HIDROGINÁSTICA NO EQUILIBRIO CORPORAL DE IDOSAS

Author

Cornélio, Jéssica da Silva e Souza, primary, Araújo, Flávio de Souza, additional, Miranda, Valcir Braga, additional, Feitoza, Rodrigo Novaes, additional, Carvalho, Nelson Lindolfo Gurgel, additional, Leite, Tatiana Braga, additional, Sá, Conrado Guerra de, additional, Pereira, Francisco Jadson, additional, and Carvalho, Rodrigo Gustavo da Silva, additional

Published
2019
Full Text
View/download PDF

45. ERROS DE MEDICAÇAO NO AMBITO HOSPITALAR: UMA ABORDAGEM MULTIPROFISSIONAL

Author

Nascimento, Alielson Araújo, primary, Carvalho, Annanda Soares, additional, Santos, Leidiane Dos, additional, Silva, Máyra Sibelle Ramos da, additional, Carvalho, Marisa da Conceição Sá de, additional, Conceição, Monica da, additional, Brito, Maria dos Remédios Mendes de, additional, Sá, Mauricio José Conceição de, additional, Carvalho, Nelson Silva, additional, and Guimaraes, Rena Araújo, additional

Published
2019
Full Text
View/download PDF

46. The use of ERS-1 synthetic aperture radar for measurement and modeling of the directional wave spectrum

Author

Violante-Carvalho, Nelson

Subjects
551, Oceanography
Abstract

The study presented in this work examines the use of Synthetic Aperture Radar (SAR) onboard the first European Remote Sensing Satellite (ERS-1) for the measurement of wind waves and discusses its applications such as wave data assimilation and inverse modeling. Since the launch of ERS-1 in 1991 the directional wave spectrum became available with high spatial and temporal global coverage. With the subsequent launch of its successors ERS-2 and ENVISAT millions of SAR wave mode (SWM) imagettes have been and are still being acquired providing a unique data set for the improvement of the understanding of the dynamics of surface gravity waves. Over four years of directional measurements acquired by a heave-pitch-roll buoy moored in tropical deep waters around 150 km offshore are employed to investigate the mechanisms of SAR wave imaging and the retrievals of wave spectra from SAR images.  new approach for the partitioning of the frequency spectrum is implemented and applied to isolate the wind sea from the swell contaminated spectra. Specifically the influence of swell on wind sea growth is analyzed in terms of their direction of propagation and separation in frequency space, with direct connection on how long waves modulate short ones. The relatively poorly understood Hydrodynamic and Tilt Modulation Transfer Functions (MTF) are discussed in the light of the findings. For the first time the most widely implemented Max-Planck Institut (MPI) SWM retrieval scheme was assessed through detailed statistical intercomparisons and selected qualitative validations against directional buoy data and against the third generation wave model WAM data - which was used as first guess to the inversion. The MPI scheme deteriorates the first guess increasing the bias and the errors of the retrievals of significant wave height, mean wave length and mean direction of propagation of short waves.

Published
2002

47. Sugarcane straw as a source of arabinoxylans: optimization and economic viability of a two-step alkaline extraction

Author

Costa, Joana R., Pereira, Maria J., Pedrosa, Sílvia S., Gullón, Beatriz, Carvalho, Nelson M. de, Pintado, Manuela E., Madureira, Ana Raquel, and Veritati - Repositório Institucional da Universidade Católica Portuguesa

Subjects
Response surface methodology, Arabinoxylan, Economic viability, Alkaline extraction, Sugarcane straws
Abstract

Sugarcane processing produces a significant amount of byproducts in the form of straw and bagasse, which are rich in cellulose, hemicellulose, and lignin. This work aims to provide a valorization approach to sugarcane straw by optimizing a two-step alkaline extraction of arabinoxylans by a response surface methodology to evaluate a potential industrial-scale production. Sugarcane straws were delignified using an alkaline–sulfite pretreatment, followed by alkaline extraction and precipitation of arabinoxylan, a two-step process optimized using a response surface methodology. A KOH concentration of (2.93–17.1%) and temperature (18.8–61.2 °C) were chosen as independent variables, and the arabinoxylan yield (%) as a response variable. The model application shows that KOH concentration, temperature, and the interaction between both independent variables are significant in extracting arabinoxylans from straw. The best-performing condition was further characterized by FTIR, DSC, and chemical and molecular weight evaluation. The straws arabinoxylans presented high purities levels, ca. 69.93%, and an average molecular weight of 231 kDa. The overall estimated production cost of arabinoxylan from straw was 0.239 €/g arabinoxylan. This work demonstrates a two-step alkaline extraction of the arabinoxylans method, as well as their chemical characterization and economic viability analysis, that can be used as a model for industrial scale-up production.

Published
2023

49. Experimental Reexamination of Transverse Tensile Strength for IM7/8552 Tape-Laminate Composites

Author

Arndt, Caitlin M, De Carvalho, Nelson V, and Czabaj, Michael W

Subjects
Nonmetallic Materials
Abstract

Due to the observed dependence of transverse-tensile strength, YT, on test geometry and specimen size, there is no consensus regarding a test method that can uniquely measure YT. This study reexamines characterization of YT by comparing results from established flexure tests with results from a new tensile test that exhibits consistent failure in the gage region. Additionally, the effects of surface preparation and direction of transverse fracture are investigated. Results show that YT is inversely proportional to specimen volume and surface roughness, and is insensitive to direction of transverse fracture. The relationship between specimen volume and YT is adequately captured by Weibull strength-scaling theory, except at the tails of the YT distributions. However, specimens exhibited microcracking prior to failure, which violates the “weak-link” assumptions of the Weibull theory. These findings highlight the challenges of using deterministic YT values in progressive damage analysis.

Published
2020

50. Mancozeb exposure results in manganese accumulation and Nrf2-related antioxidant responses in the brain of common carp Cyprinus carpio

Author

Costa-Silva, Dennis Guilherme, Lopes, Andressa Rubim, Martins, Illana Kemmerich, Leandro, Luana Paganotto, Nunes, Mauro Eugênio Medina, de Carvalho, Nelson Rodrigues, Rodrigues, Nathane Rosa, Macedo, Giulianna Echeveria, Saidelles, Ana Paula, Aguiar, Cassiana, Doneda, Morgana, Flores, Erico Marlon Moraes, Posser, Thais, and Franco, Jeferson Luis

Published
2018
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results