Pulse Echo
Mostrando 1-12 de 39 artigos, teses e dissertações.
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1. Droplet Size Distribution in Water-Crude Oil Emulsions by Low-Field NMR
This paper reports the droplet size distribution (DSD) measurements in 28 W/O (water/oil) crude oil emulsions prepared with two Brazilian oils (medium and heavy) under different shear conditions using both 10 g L-1 NaCl solution and water production by low field nuclear magnetic resonance (NMR, 2.2 MHz). The PFGSTE (pulsed-field gradient-stimulated echo) pul
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
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2. Ultrasound method applied to characterize healthy femoral diaphysis of Wistar rats in vivo
A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated
Braz J Med Biol Res. Publicado em: 04/04/2014
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3. Simulação de sinais de RMN através das equações de Bloch
The aim of this paper was to present a simple and fast way of simulating Nuclear Magnetic Resonance signals using the Bloch equations. These phenomenological equations describe the classical behavior of macroscopic magnetization and are easily simulated using rotation matrices. Many NMR pulse sequences can be simulated with this formalism, allowing a quantit
Quím. Nova. Publicado em: 2014
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4. Análise do teor e da qualidade dos lipídeos presentes em sementes de oleaginosas por rmn de baixo campo
To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field ¹H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation
Quím. Nova. Publicado em: 2014
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5. Effect of scanner acoustic background noise on strict resting-state fMRI
Functional MRI (fMRI) resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state’ fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influ
Braz J Med Biol Res. Publicado em: 12/04/2013
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6. Efeito da correção cirúrgica nas variáveis do teste cardiopulmonar de exercício em pacientes com insuficiência mitral crônica. / Effect of surgical correction on cardiopulmonary exercise testing in patients with organic mitral regurgitation.
Introduction: Chronic organic Mitral Regurgitation (MR) has a complex physiopathology. The symptoms of heart failure and functional capacity worsening may appear too late, when a left ventricle (LV) contractile dysfunction already exists. The cardiopulmonary exercise testing (CPET) may objectively assess the functional capacity and helps in the medical condu
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 09/05/2012
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7. Reconhecimento de PadrÃes AtravÃs de AnÃlises EstatÃsticas e Fractais Aplicadas a Dados de Ensaios NÃo-Destrutivos / Pattern Recognition by Statistical Fluctuation and Fractal Analyses Applied to Nondestructive Testing Data
In this work a procedure is studied for pattern classification related to different types of data, namely: (1) signals obtained from ultrasonic testing ( pulse-echo technique) and magnetic signals obtained from BarkhÃusen noise in samples of ferritic-pearlitic carbon steel tubes which, due to temperature effects, have shown microstructural changes as conseq
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/12/2011
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8. Modelagem de ondas ultrassônicas refletidas por superfícies de geometrias diversas. / Modeling for ultrasonics waves of reflected surfaces of various geometries.
Neste trabalho são analisados os campos acústicos gerados por transdutores ultrassônicos planos e circulares, do tipo pistão plano, no modo pulso-eco, trabalhando como emissor e receptor de ondas, com freqüências de 1,6 MHz, 2,25 MHz e 5 MHz. As ondas emitidas por esses transdutores interagem com interfaces denominadas alvos, com diversas geometrias de
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 20/05/2011
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9. Ultrasonic inspection of AA6013 laser welded joints
Interest in laser beam welding for aerospace applications is continuously growing, mainly for aluminum alloys. The joints quality is usually assessed by non-destructive inspection (NDI). In this work, bead on plate laser welds on 1.6 mm thick AA6013 alloy sheets, using a 2 kW Yb-fiber laser were obtained and inspected by pulse/echo ultrasonic phased-array te
Materials Research. Publicado em: 26/08/2011
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10. Efeito do envelhecimento por ciclagem mecânica ou ciclagem em autoclave na resistência à flexão de cerâmicas odontológicas / Mechanical and autoclave cycling effect on flexural strength of dental ceramics
The aims of this study were: to perform a microestrutural analysis of dental ceramics and correlate the results with the flexural strength obtained; to evaluate two aging process (mechanical cycling and autoclave cycling) on the flexural strength of the materials and to evaluate the specimen configuration (bar or disc) on the flexural strength of mechanical
Publicado em: 2010
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11. Use of steady state free precession (SSFP) to enhance signal to noise ratio in high resolution NMR / Desenvolvimento da técnica de precessão livre no estado estacionário para aumento da razão sinal ruído em espectros de RMN de alta resolução
It was performed a detailed analysis of the advantages and disadvantages of Steady State Free Precession (SSFP) sequence for a rapid acquisition of 13C Nuclear Magnetic Resonance (NMR) spectra. The SSFP regime is obtained by the application of a pulse train with the same phase, duration and intensity, separated by a time interval (Tp) shorter than the transv
Publicado em: 2009
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12. Mechanical properties and porosity of dental glass-ceramics hot-pressed at different temperatures
The objective of this work was to evaluate biaxial-flexural-strength (σf), Vickers hardness (HV), fracture toughness (K Ic), Young's modulus (E), Poisson's ratio (ν) and porosity (P) of two commercial glass-ceramics, Empress (E1) and Empress 2 (E2), as a function of the hot-pressing temperature. Ten disks were hot-pressed at 1065, 1070, 1075 and 1080 °C f
Materials Research. Publicado em: 2008-09