115 research outputs found
Numerical modeling of infrared thermography techniques via ANSYS
Several inspection techniques have been developed over years. Recently, infrared thermography (IRT) technology has become a widely accepted as a nondestructive inspection (NDI) technique for different fields and various applications as well. Infrared thermography stands as one of the most an attractive and a successful NDI technique that has ability to detect the object\u27s surface/subsurface defects remotely based on observing and measuring the surface\u27s emitted infrared heat radiation by using an infrared camera. The finite element modeling FEM ANSYS was successfully used for the modelling of several IRT techniques; such as Pulsed Thermography (PT) and Lock-in Thermography (LT) that can be used to detect the in-plane defects which are parallel to its surface; besides a Laser Spot Thermography (LST) technique that can be used to detect the cracks which are perpendicular to its surface. Furthermore; this thesis describes how LST method can be extended to a new technique, Laser Digital Micromirror Thermography (LDMT), based on using a digital micromirror device (DMD) that has ability to generate multi-hot spots onto the specimen\u27s surface being examined by using single laser source.
In one hand, this thesis aims to show investigations about infrared thermography technology as a non-destructive inspection (IRT-NDI) by using numerical modeling methods via ANSYS. On the other hand, this thesis presents FEM ANSYS as a powerful tool allows doing several inspections, analyses, and evaluations of thermography techniques tests based on numerical modeling simulations and comparing their results to the corresponding experiments in literature experiment tests to validate these simulations and show a reasonable agreement to use ANSYS as a thermography inspection tool for future study and researches --Abstract, page iii
Numerical modeling of infrared thermography techniques via ANSYS
Several inspection techniques have been developed over years. Recently, infrared thermography (IRT) technology has become a widely accepted as a nondestructive inspection (NDI) technique for different fields and various applications as well. Infrared thermography stands as one of the most an attractive and a successful NDI technique that has ability to detect the object\u27s surface/subsurface defects remotely based on observing and measuring the surface\u27s emitted infrared heat radiation by using an infrared camera. The finite element modeling FEM ANSYS was successfully used for the modelling of several IRT techniques; such as Pulsed Thermography (PT) and Lock-in Thermography (LT) that can be used to detect the in-plane defects which are parallel to its surface; besides a Laser Spot Thermography (LST) technique that can be used to detect the cracks which are perpendicular to its surface. Furthermore; this thesis describes how LST method can be extended to a new technique, Laser Digital Micromirror Thermography (LDMT), based on using a digital micromirror device (DMD) that has ability to generate multi-hot spots onto the specimen\u27s surface being examined by using single laser source.
In one hand, this thesis aims to show investigations about infrared thermography technology as a non-destructive inspection (IRT-NDI) by using numerical modeling methods via ANSYS. On the other hand, this thesis presents FEM ANSYS as a powerful tool allows doing several inspections, analyses, and evaluations of thermography techniques tests based on numerical modeling simulations and comparing their results to the corresponding experiments in literature experiment tests to validate these simulations and show a reasonable agreement to use ANSYS as a thermography inspection tool for future study and researches --Abstract, page iii
Demonstrating testâretest reliability of electrophysiological measures for healthy adults in a multisite study of biomarkers of antidepressant treatment response
Growing evidence suggests that loudness dependency of auditory evoked potentials (LDAEP) and resting EEG alpha and theta may be biological markers for predicting response to antidepressants. In spite of this promise, little is known about the joint reliability of these markers, and thus their clinical applicability. New standardized procedures were developed to improve the compatibility of data acquired with different EEG platforms, and used to examine testâretest reliability for the three electrophysiological measures selected for a multisite projectâEstablishing Moderators and Biosignatures of Antidepressant Response for Clinical Care (EMBARC). Thirtyânine healthy controls across four clinical research sites were tested in two sessions separated by about 1 week. Resting EEG (eyesâopen and eyesâclosed conditions) was recorded and LDAEP measured using binaural tones (1000 Hz, 40 ms) at five intensities (60â100 dB SPL). Principal components analysis of current source density waveforms reduced volume conduction and provided referenceâfree measures of resting EEG alpha and N1 dipole activity to tones from auditory cortex. Lowâresolution electromagnetic tomography (LORETA) extracted resting theta current density measures corresponding to rostral anterior cingulate (rACC), which has been implicated in treatment response. There were no significant differences in posterior alpha, N1 dipole, or rACC theta across sessions. Testâretest reliability was .84 for alpha, .87 for N1 dipole, and .70 for theta rACC current density. The demonstration of goodâtoâexcellent reliability for these measures provides a template for future EEG/ERP studies from multiple testing sites, and an important step for evaluating them as biomarkers for predicting treatment response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135271/1/psyp12758_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135271/2/psyp12758.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135271/3/psyp12758-sup-0001-suppinfo1.pd
Robust Pre-Clinical Software System for Real Time NIRS and EEG Monitoring
RĂSUMĂ
Ce mĂ©moire prĂ©sente la conception et lâimplĂ©mentation dâun logiciel dĂ©diĂ© au support dâun systĂšme bimodal NIRS et EEG dâimagerie cĂ©rĂ©brale en temps rĂ©el. En effet, lâaccĂšs Ă lâinformation en temps rĂ©el concernant lâactivitĂ© cĂ©rĂ©brale est un facteur important permettant la dĂ©tection de tout changement au niveau cortex du cerveau Ă un stade prĂ©coce. Or, les logiciels actuellement disponibles comparables Ă celui prĂ©sentĂ© ici nâoffrent quâune possibilitĂ© dâajustement limitĂ©e des paramĂštres en temps rĂ©el ainsi que peu de fonctionnalitĂ© permettant lâanalyse rapide et efficace des donnĂ©es.
Le travail prĂ©sentĂ© dans ce prĂ©sent mĂ©moire a Ă©tĂ© rĂ©alisĂ© au sein du groupe IMAGINC. Un groupe de recherche multidisciplinaire ayant comme objectif le dĂ©veloppement dâun systĂšme dâimagerie cĂ©rĂ©brale portatif, non invasif et sans-fil permettant dâimager le cortex entier en temps rĂ©el. Le module dâacquisition de donnĂ©es de ce systĂšme enregistre lâinformation de 128 canaux NIRS et 32 canaux EEG ainsi que diffĂ©rents accĂ©lĂ©romĂštres et canaux analogiques le tout par lâentremise dâoptodes et dâĂ©lectrodes placĂ©es sur un casque dâenregistrement. Ces donnĂ©es sont ensuite envoyĂ©es par un lien de communication sans-fil au logiciel qui recueille et affiche lâĂ©tat hĂ©modynamique du sujet par lâentremise de son interface graphique. Il est ensuite possible de choisir diffĂ©rentes vues des cartes 2D du cerveau sur lesquelles les changements hĂ©modynamiques sont prĂ©sentĂ©s. La surveillance Ă distance de lâĂ©tat du sujet est aussi possible puisque ces donnĂ©es peuvent ĂȘtre retransmises vers un autre ordinateur par un lien sans-fil. De plus, de par son interface graphique conviviale et intuitive, lâusager peut facilement ajuster diffĂ©rents paramĂštres de test tout au long de lâacquisition de donnĂ©es sans mĂȘme lâinterrompre. Dans le but dâoptimiser les paramĂštres pour chaque sujet, une fonction de calibration automatique ajustant lâintensitĂ© dâillumination de chacun des Ă©metteurs en quelques secondes a Ă©tĂ© implĂ©mentĂ©e. Pour faciliter le processus de test, il est possible de tĂ©lĂ©charger des fichiers (bipolaire et montage rĂ©fĂ©rentielle) contenant des paramĂštres de configurations prĂ©Ă©tablies pour le NIRS et lâEEG. Enfin, il est possible de faire une analyse automatique et rapide de lâĂ©tat de tous les canaux NIRS durant les tests afin dâassurer une bonne connexion ainsi que la validitĂ© des donnĂ©es. Le systĂšme conçu est en mesure dâenregistrer et de traiter des donnĂ©es en temps rĂ©el sur une pĂ©riode de 24 heures. Les rĂ©sultats obtenus ont Ă©tĂ© validĂ©s en utilisant des logiciels dâanalyse de donnĂ©es NIRS similaires durant des tĂąches de finger tapping induisant un changement hĂ©modynamique chez les sujets.----------ABSTRACT
This masterâs thesis presents the design and implementation of a real-time software system to support a bimodal NIRS and EEG brain imaging device. Real-time information on brain activity is an important factor in early detection and diagnosis at the top level of the cortex of various brain disorders. Current software systems provide limited real-time parameter adjustment and automated features for quick and easy analysis.
The project presented in this masterâs thesis is part of the multidisciplinary IMAGINC research group, with the objective of developing a wireless, non-invasive and portable brain imaging system that allows imaging of the whole cortex in real time. The hardware system is capable of recording data from 128 NIRS and 32 EEG channels, as well as additional accelerometer and analog channels through the optodes and electrodes mounted onto the helmet. The software system acquires the real-time data from the hardware module using a wireless connection and displays the hemodynamic variations on the user interface. The change in hemodynamic activity is displayed on a 2D map of the brain, with selection of different views. Remote monitoring is also possible since the data can be transferred wirelessly to another computer. Through the user-friendly and intuitive user interface, the user can control and adjust various test parameters throughout the acquisition without any interruption. In order to achieve maximum illumination setting for individual subjects there is an automatic calibration function that quickly adjusts the illumination intensity for each of the emitters in just a few seconds. Previously defined NIRS and EEG configuration files (bipolar and referential montage) can be uploaded for easy testing. An automated analysis feature quickly analyzes and reports the status of all NIRS channels during the test to ensure good connection and valid results.
The designed system can successfully record and process data for a continuous period of up to 24 hours. The results have been validated using similar NIRS data analysis software during figure tapping tasks and the hemodynamic variations were as expected
Data Display, Acquisition and Feedback System for Biomedical Experiments
Biomedical signals have various research applications in prosthetic limb development and other control applications. Consequently, a workstation that can be used to conduct biomedical experiments using EMG and other similar signals can be beneficial to the continuation of research in this growing field. We have investigated the possibility of creating a PC-based workstation to conduct these experiments using National InstrumentĂąâŹâąs LabVIEW. Our work suggests that such a system can not be used with experiments that require hard real-time control
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