Search results for "Acoustic Emission"
showing 10 items of 56 documents
Rib-Roller Wear in Tapered Rolling Element Bearings: Analysis and Development of Test Rig for Condition Monitoring
2020
Rolling Element Bearings (REBs) are present in virtually all machines with moving or rotating parts, and are vital for proper performance and safe operation. Condition Monitoring (CM) of bearings often receive particular interest, as this component group rarely reach design lifetime and hence is responsible for unplanned machine downtime. Unplanned maintenance can represent a large cost which motivates development of improved CM methods for implementation of advanced maintenance regimes. Based on observations of a used bearing from an offshore drilling machine, wear on roller ends in the rib-roller contact area was identified as an area of interest for future research. A test rig for creati…
Integrated System for Monitoring the Tool State Using Temperature Measuring by Natural Thermocouple Method
2014
The intensive developments of intelligent manufacturing systems in the last decades open the large possibilities of more accurate monitoring of the metal cutting process. One of the most important factors of the process is the tool state given by the rate of the tool wear, which is the result of a lot of influences of almost all cutting parameters. The modern tool monitoring systems relieved that the accuracy of the results increases when using a combination of surveyed signals such as: vibrations, power consumption, acoustic emission, forces or tool temperature. Combining the output signals in a monitoring function using the neural network method gives the best results when using on-line m…
The influence of the momentum coefficient and the number of the averaging points of the power spectrum density on the recognition effectiveness of th…
2006
The subject matter of this paper refers to the next stage of the research work connected with the improvement of the acoustic emission method (AE) used for the evaluation of partial discharges (PDs) generated in paper-oil insulation systems of high-voltage power appliances. The subject matter discussed here refers to one of the aspects of the analysis of the signals registered - a correct and effective recognition of the AE signals generated by basic PD forms. The paper presents research results of the application of the unidirectional artificial neuron networks (ANN) used for the recognition of basic PD forms that can occur in paper-oil insulation impaired by aging processes.
Cutting Conditions and Work Material State Identification through Acoustic Emission Methods
1992
Summary This paper examines the problem of in-process monitoring of metal cutting operations carried out on aluminum alloys for aeronautical applications. Turning tests were conducted on annealed and heat treated aluminum alloy bars, using carbide tools. For both work material conditions, different combinations of cutting parameters were used. During cutting tests, acoustic emission (AE) and cutting force sensor data were detected and processed. The comparison between AE responses from the annealed and heat treated aluminum alloys allowed, with the help of force sensor data, to verify the applicability of AE and sensor fusion techniques for in-process and real time identification of work ma…
Detección precoz de la hipoacusia, influencia en el diagnóstico y en el tratamiento temprano
2021
Detección precoz de la hipoacusia, influencia en el diagnóstico y en el tratamiento temprano. INTRODUCCIÓN: La hipoacusia es el déficit sensorial mas frecuente en los países desarrollados. La prevalencia de cualquier grado de hipoacusia es de un 2-3 % de la población infantil y el 80% de las mismas, está presente al nacimiento. Los programa de screening auditivo (SA) se justifican por la alta incidencia de la hipoacusia y sus consecuencias devastadoras para el lenguaje cuando no se detecta precozmente. OBJETIVO: Establecer el número de niños diagnosticados de hipoacusia congénita gracias al SA en el hospital Universitario La Fe. Analizamos las técnicas utilizadas en el cribado, los parámetr…
1992
Distortion product otoacoustic emissions in healthy newborns: normative data.
1995
Distortion product otoacoustic emissions (DPOAE) offer an alternative to transiently evoked otoacoustic emissions (TEOAE) as an audiological test. The former can be used as a screening technique, and may also provide frequency-specific information about the functional state of the cochlea. We recorded DPOAE in a group of healthy newborns to establish the Characteristics of a DPOAE “audiogram” (DP-gram) in this population. The DP-gram can be obtained with characteristics quite similar to those observed in adults, with two sharp peaks of maximum amplitude at F2 frequencies of 2 kHz and 5-6 kHz, and a decline in DPOAE amplitude in mid frequencies. The results confirm the limitations of DPOAE r…
Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation
2021
Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity <1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigat…
Analytical and finite element analyses on reliability of carbon fibre reinforced plastics
2013
International audience
Verbesserte Auswertbarkeit transitorisch evozierter otoakustischer Emissionen durch Korrelationsfilterung
1993
Hearing screening as well as evaluation of cochlear function under therapy with ototoxic agents or patients with various diseases is increasingly done by registration of transient evoked otoacoustic emissions (TEOAE). Usually the standard system ILO 88 Otodynamic Analyser is used, where until now emissions were analyzed subjectively. However, evaluation of signals may be difficult mainly in the hearing threshold area. In this article we describe a method to mathematically analyze registered emissions by correlation-filtering. This allows to better identify small specific responses, to further increase the sensitivity of TEOAE, and offers a more objective means for audiologic diagnoses.