Acoustic Emission
Mostrando 37-48 de 62 artigos, teses e dissertações.
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37. Avaliação do comportamento fisico-quimico-mecanico de misturas cimento-cinza-casca de arroz por meio de corpos-de-prova cilindricos e placas prensadas
The recycling is an effective tool to minimize environmental impact that is caused by human civilization. The utilization agricultural residual for rural construction is an efficient way for retain or reduce carbon emission to the atmosphere. However, the present-day techno logy is not enough to be a satisfactory level. A part of the residue is not consumed,
Publicado em: 2007
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38. DC electric field effects on the electron dynamics in double rectangular quantum dots
The effect of a dc electric field on the temporal evolution of an electron in a double rectangular quantum dot is explored in this work. In the framework of the effective mass approximation, first-order scattering rates for interaction between confined electron-''free'' electron and electron-longitudinal acoustic phonon at room temperature are calculated in
Brazilian Journal of Physics. Publicado em: 2006-09
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39. Automatic system for thermal damage detection in manufacturing process with internet monitoring
This work involved the development of a smart system dedicated to surface burning detection in the grinding process through constant monitoring of the process by acoustic emission and electrical power signals. A program in Visual Basic® for Windows® was developed, which collects the signals through an analog-digital converter and further processes them usi
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2006-06
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40. In-process grinding monitoring through acoustic emission
This work aims to investigate the efficiency of digital signal processing tools of acoustic emission signals in order to detect thermal damages in grinding processes. To accomplish such a goal, an experimental work was carried out for 15 runs in a surface grinding machine operating with an aluminum oxide grinding wheel and ABNT 1045 Steel as work material. T
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2006-03
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41. A methodology for noise prediction of turbofan engines.
A computional model is developed for prediction of noise emission from na existing or new turbofan engine. This model allows the simulation of noise generation from high bypass ratio turbofan engines, appropriate for use with computational programs for gas turbine performance developed at ITA. Analytical and empirical methods are used for spectrum shape, spe
Publicado em: 2006
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42. Aspectos fisiologicos e fisicos da orelha como emissora de sons / Physics and physiological aspects of the ear as a sound emitter system
Ear is the sound receptor in our body. Sound is captured and driven through external ear, amplified and modulated in middle ear and transduced to electrical sign in internal ear. However, otoacoustic emissions and objective tinnitus are examples of an inverse process, where ear can be a sound emitter. Trying to understand some of theses events, in which soun
Publicado em: 2006
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43. Study of thresholds to burning in surface grinding process
This work aims at finding out the threshold to burning in surface grinding process. Acoustic emission and electric power signals are acquired from an analog-digital converter and processed through algorithms in order to generate a control signal to inform the operator or interrupt the process in the case of burning occurrence. The thresholds that dictate the
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2005-06
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44. Efeitos da Segmentação em Sistemas Híbridos ANN+HMM
The Hidden Markov Models has become the widely used speech recognition framework due to its solid probabilistic approach. However, this robustness is damaged when the Markov chains are trained under the maximum likelihood method, which is poor in discriminative power. Until now several efficient techniques and algorithms have been developed to increase the p
Publicado em: 2005
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45. Time-dependent behavior of sulphatic rocks of the anhydrite and gypsum / Comportamento dependente do tempo de rochas sulfáticas de anidrita e gipso
The purpose of this thesis is to contribute for the knowledge of time-dependent behavior of sulfatic rocks of anhydrite and gypsum. Emphasis is given to provide straightforward arguments about physical mechanisms responsible for creep observed in some underground excavations in those rocks in Europe. Explanation for this phenomena is not clear yet and studie
Publicado em: 2005
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46. CaracterizaÃÃo de Sinais de EmissÃo AcÃstica em Ensaios CTOD por AnÃlise Fractal / Characterization of Acoustic Emission Signals in CTOD tests by Fractal Analysis
A pesquisa teve como objetivo correlacionar diferentes defeitos e suas criticidades, em corpos de prova de aÃo ASTM A516 grau 60 para ensaio CTOD, cujos detalhes foram feitos no metal de base, no metal de solda e na zona termicamente afetada de uma junta soldada, com os sinais de emissÃo acÃstica obtidos durante os ensaios. Quatro mÃtodos de anÃlise fra
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 10/09/2004
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47. CaracterizaÃÃo de Defeitos de Soldagem por AnÃlise Fractal Utilizando EmissÃo AcÃstica em Ensaios de TraÃÃo / Characterization of welding defects Fractal Analysis Using Acoustic Emission in Tensile Tests
O presente trabalho tem como objetivo caracterizar e correlacionar formas de onda de sinais de emissÃo acÃstica, utilizando mÃtodos de anÃlise espectral e fractal, em corpos de prova previamente soldados com seus respectivos defeitos, avaliando assim a integridade estrutural do material aÃo carbono ASTM 516 Grau 60, utilizado em vasos de pressÃo, tubul
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 01/03/2004
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48. Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel
New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wh
Materials Research. Publicado em: 2004-09