Data/hora: 05/06/2024 12:57:31

Biblioteca(s): | Embrapa Instrumentação.
Data corrente: | 22/12/1999
Data da última atualização: | 22/12/1999
Autoria: | POSADAS, D. A.; TANNUS, A.; PANEPUCCI, H.; CRESTANA, S.
Afiliação: | Universidade Estadual de Ponta Grossa; EMBRAPA-CNPDIA; USP-IFSC.
Título: | Magnetic resonance imaging as a non-invasive technique for investigating 3-D preferential flow occurring within stratified soil samples.
Ano de publicação: | 1996
Fonte/Imprenta: | Computers and Electronics in Agriculture, Amsterdam, v.14, n.4, p.255-267, Apr. 1996.
Idioma: | Inglês
Conteúdo: | The soil fingering phenomenon was investigated using magnetic resonance imaging (MRI) as an appropriate technique. A cubic 15x15x15-cm3 double-layer sand column was built in order to simulate the stratified soil. The column was imaged in a 500 Gaus NMR tomograph [IFQSC, USP, Sao Carlos (SP)]. After reaching the water steady-state flow several coronal, transverse, and sagittal images of the column were obtained. For each case seven slices, 1.8cm thick and separated by 2.0cm center to center, were collected providing three-dimensional information regardingto the number of fingers, their sizes and diameters. To study the fingering dynamics employing MRI concepts, another kind of experiment was performed by following only the water front (no image reconstruction), using spin-echo signals with phase encoding along vertical axis (gravitational direction), but with phase encoding gradients switched off. Sixteen acquisitions of seven transverses of 2cm thick slices, were performed in a 3-min experiment. After suitable treatment, the water front and the horizontal distribution at each measured time during the water infiltration process was obtained. Normalizing the signal intensities to the soil column dimensions and using computational graphic resources, made it possible to quantify the number of fingers and their spatial and temporal variability. The results elect MRI as a valuable tool for non-invasively investigating the dynamics of soil fingering phenomenon.
Palavras-Chave: | Fingering; Fractal; Gravity force; Imaging; NMR tomography; Nuclear magnetic resonance; Spin echo signal.
Categoria do assunto: | --
Registro original: | Embrapa Instrumentação (CNPDIA)
Exemplares: | CNPDIA - (5039-1) - UPC - SP - -- - PROCI-96.00167 -  - 1996.00167 - DIS