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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Online Environmental Control of Multiple Devices using Transcranial Doppler (TCD) Ultrasonography

Aleem, Idris Syed 20 November 2012 (has links)
Individuals with severe impairments may use brain-computer interface (BCI) technologies in order to interact with their external environment. One non-invasive brain-monitoring technology which may be suitable for this purpose is transcranial Doppler ultrasound (TCD). Previous research has shown that TCD is useful in detecting changes in cerebral blood flow velocities after the performance of cognitive tasks which are often lateralized towards a specific hemisphere of the brain. However, to date, TCD has not been used in a BCI system. This thesis first explores TCD in an offline study, showing that on average, accuracies of 80.0% are attainable with user-specific training data and 74.6% with user-independent training data. Furthermore, consecutive sequential lateralizations do not decrease classification accuracies. In a subsequent online experiment, a TCD-BCI system yielded an average accuracy of 61.4%, but revealed key findings about the effects of user motivation and error streaks in an online system.
2

Online Environmental Control of Multiple Devices using Transcranial Doppler (TCD) Ultrasonography

Aleem, Idris Syed 20 November 2012 (has links)
Individuals with severe impairments may use brain-computer interface (BCI) technologies in order to interact with their external environment. One non-invasive brain-monitoring technology which may be suitable for this purpose is transcranial Doppler ultrasound (TCD). Previous research has shown that TCD is useful in detecting changes in cerebral blood flow velocities after the performance of cognitive tasks which are often lateralized towards a specific hemisphere of the brain. However, to date, TCD has not been used in a BCI system. This thesis first explores TCD in an offline study, showing that on average, accuracies of 80.0% are attainable with user-specific training data and 74.6% with user-independent training data. Furthermore, consecutive sequential lateralizations do not decrease classification accuracies. In a subsequent online experiment, a TCD-BCI system yielded an average accuracy of 61.4%, but revealed key findings about the effects of user motivation and error streaks in an online system.
3

Integration of a micro-gas chromatography system for detection of volatile organic compounds

Navaei, Milad 21 September 2015 (has links)
The focus of this dissertation is on the design and micro-fabrication of an all silicon gas chromatography column with a novel two dimensional resistive heater and on its integration with an ultra-low power Thermal Conductivity Detector (TCD) for fast separation and detection of Volatile Organic Compounds (VOC). The major limitations of the current MEMS-GC column are: direct bonding of silicon to silicon, and peak band broadening due to slow temperature programming. As part of this thesis, a new gold eutectic-fusion bonding technique is developed to improve the sealing of the column. Separation of BETX, alkane mixture and VOCs were demonstrated with the MEMS GC column. The time and power required to ramp and sustain the column’s temperature are very high for the current GC columns. To reduce the time required to separate the compounds, a new temperature gradient programming heating method was developed to generate temperature gradients along the length of the column. This novel heating method refocuses eluding bands and counteracts some of the chromatographic band spreading due to diffusion resulting in an improved separation performance. A low power TCD was packaged and tested in a GC by comparison against FID for the detection of a mixture of VOCs. It demonstrated low power operation of a few milliwatts and a very fast response. The MEMS-GC was also demonstrated for rapid detection of the VOC gases released by pathogenic species of Armillaria fungus.
4

Integrating the SWEET WCET Analyzer into ARM-GCC with Extra WCFP Information to Enable WCET-Targeted Compiler Optimizations

Hao, Wen-Chuan 23 December 2011 (has links)
Finding the worst-case execution time (WCET) on a hard real-time system is extremely important. Only static WCET analysis can give us an upper bound of WCET which guarantees the deadline, however, industrial practice still relies on measurement-based WCET analysis, even for many hard real-time systems; because static analysis tools are not a mature technology. We use SWEET (SWEdish Execution Time tool) to provide WCET analysis support for the ARM. SWEET is a static WCET analyzer developed by the Mälardalen Real-Time Research Center (MRTC). We modified ARM-GCC to obtain input files in specific format for SWEET: ALF, TCD, and MAP. Besides, for WCET optimization supporting and over-optimizing issue, we modified SWEET to obtain additional worst-case flow path (WCFP) and the second worst-case information. By testing with benchmark files from [1], our modified ARM-GCC can create correct input files for SWEET, and also the modified SWEET can produce additional worst-case information.
5

Autismo, tecnologia e aprendência: de ritornelo e de polifonia / Autismo, tecnología y aprendencia: de ritornelo y de polifonía

Kliemann, Marciana Pelin 05 February 2018 (has links)
Submitted by Rosangela Silva (rosangela.silva3@unioeste.br) on 2018-05-21T19:40:49Z No. of bitstreams: 2 Marciana Pelin Kliemann.pdf: 12222302 bytes, checksum: c06da19274050932456a3e334c303a76 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-21T19:40:49Z (GMT). No. of bitstreams: 2 Marciana Pelin Kliemann.pdf: 12222302 bytes, checksum: c06da19274050932456a3e334c303a76 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-05 / Las reflexiones presentes en esta tesis son de cuño exploratorio y tienen por finalidad explicitar metodologías adecuadas para la intervención de los profesores junto a los sujetos autistas de cuatro colegios públicos de Cascavel -Pr, elegidos por hacer parte de la región periférico oeste del municipio y por atender a autistas con laudo psicopedagógico, considerando el acuerdo con lo dispuesto en la ley de inclusión, Lei Nº 13.146, de 6 de julho de 2015, que les asegura la atención, por presentar especificidades individuales de comprensión y por poseer una condición financiera desfavorecida. Nuestra intención es hacer una experimentación pedagógica con el autista, empleando la tecnología para percibir si éstas fomentan e instigan el proceso de adquisición de los conocimientos curriculares y, así, aducen avances en la interacción y en el desarrollo comunicativo del autista. Este propósito se dará por el uso constante de la Tecnología de Comunicación Digital (TCD), del Levy, que, según nuestra comprensión, se presenta como una condición no lineal, o sea idiosincrática, para la enseñanza y el aprendizaje y, por operar con disponibilidad de la información, partícipes a transformarla en conocimiento, instigando el raciocinio lógico del sujeto con TEA. El proceso investigativo se ancla en las teorías de la Lingüística Aplicada, sostenido por el abordaje cualitativo de la investigación-acción en estudio de caso. El marco teórico es anclado en el concepto de crudo de rizoma, ritornelo y experimentación pedagógica, acaparando la inter y la transdisciplinariedad, y la transversalidad de Assmann. También están presentes en nuestra tesis el respeto a la singularidad ya la multiplicidad, que componen el acto educativo, especialmente, orientados al desarrollo integral del autista con la presencia de la TCD como coadyuvante de la experimentación pedagógica, comprendida aquí como Aprendência y relacionada con las inteligencias múltiples de Gardner. / As reflexões presentes nesta tese são de cunho exploratório e têm por finalidade explicitar metodologias adequadas para a intervenção dos professores junto aos estudantes autistas de quatro colégios estaduais da região periférica oeste do município de Cascavel – PR, escolhidos por possuírem laudo psicopedagógico, tendo em vista o disposto na lei de inclusão, Lei Nº 13.146, de 6 de julho de 2015, que lhes assegura o atendimento às especificidades individuais de compreensão e por possuírem uma condição financeira desfavorecida.O intuito desta Tese foi realizar uma Experimentação Pedagógica com cinco estudantes autistas e uma investigação sobre educação inclusiva e o emprego da Tecnologia de Comunicação Digital (TCD) com 62 professores, de modo a perceber se estas fomentam e instigam o processo de aquisição dos conhecimentos curriculares e, assim, levam os autistas a auferir avanços na interação e no seu desenvolvimento comunicativo e cognitivo. Esse propósito tem como via a utilização constante da Tecnologia de Comunicação Digital (TCD), Levy, que, segundo nossa compreensão, apresenta-se como uma condição não linear, ou seja, idiossincrática, para o ensino e a aprendizagem, e por operar com a disponibilização da informação, convidando os partícipes a transformá-la em conhecimento, instigando o raciocínio lógico, a linguagem e a interação. O processo investigativo se ancora nos pressupostos da Linguística Aplicada, sustentado pela abordagem qualitativa da pesquisa em ação, em um estudo de caso. O arcabouço teórico é ancorado no conceito deleuziano de rizoma, ritornelo e experimentação pedagógica, açambarcando a transdisciplinaridade e a transversalidade de Assmann. Também estão presentes em nossa Tese o respeito à singularidade e à multiplicidade, que compõem o ato educativo, especialmente voltado ao desenvolvimento integral do autista com a presença da TCD como coadjuvante da experimentação pedagógica, compreendida, aqui, como Aprendência e relacionada com as inteligências múltiplas de Gardner.
6

Magnetic resonance imaging and anthropometric measurements: a correlational study in fixed fetal specimens

Wickum, Mary Ellen 22 January 2016 (has links)
For many decades the Boston University School of Medicine Department of Anatomy and Neurobiology has housed an unprovenienced collection of fetal specimens. At least ten percent of the 137 fetal specimens were lost due to drying out and other damage. The specimens were stored for many decades in individual fluid filled containers. There is no reliable information regarding the medical or curation histories of the human fetal specimens. Furthermore, there is concern that the fixative may have led some internal structures to shrink more than others. At issue was to determine whether the specimens had maintained or lost their relationships, and size amongst internal structures. In normal fetal development the cerebellum, the femur, and the foot all follow mostly positive linear growth with age. Therefore, the purpose of the present study was to assess whether these specimens demonstrate anatomical correlations that one might find within in utero fetuses. This prospective correlation study used MRI images of the cerebellum and femur as well as anthropometric measurements of each foot and mass to seek to answer this question. A blind, random sample of twenty-five specimens was selected from forty-eight specimens roughly grouped by size. The Boston University Institutional Review Board was notified and, assigned waiver status to the application because the specimens were unprovenienced fixed tissue. All specimens were magnetic resonance scanned at the Center for Biomedical Imaging at the Boston University School of Medicine using a 3.0T whole body scanner (Achieva, Philips Healthcare, Best, The Netherlands). All scans were acquired using the 8-channel high-resolution head coil made by Invivo for the Achieva 3T scanner. This study found that the measurements taken from the images, and the feet had good intra-rater reliability because paired t-tests did not show significant differences between the measurements (alpha (α) < 0.05, all p-values were > 0.17, t-values were less than t-critical, and R2 < 0.02). Pearson's correlation coefficient testing revealed strong positive correlation between all the mean measures comparing these three structures: transverse cerebellar diameter (TCD), femur length, and foot length (α < 0.05, r - values were > 0.91, p < 0.001, and R2 > 0.82). Leading us to conclude that the dimensions of the soft tissues - TCD; and bone tissues - femur and foot of the lower extremities were unlikely to have changed significantly in decades of storage.
7

Estimating the Capacity of Visual Short-Term Memory: A Transcranial Doppler Sonography Study

Barrett, Natasha Ann 28 November 2007 (has links)
Estimates of the capacity of visuospatial short-term memory (VSTM) have ranged from less than 1 item to 4 +/- 1 items. The purpose of the present study was to find the capacity of VSTM by looking at the contribution of the other working memory systems (phonological loop and central executive) and determine the factor that limits VSTM capacity (either number of objects or object complexity). In this study, the psychophysiological measure of cerebral blood flow velocity also was incorporated to determine whether changes in cerebral blood flow velocity were indicative of VSTM performance and capacity. Both performance measures and cerebral blood flow velocity indicate that capacity for random polygons is approximately one object. Complexity of the objects affected capacity, such that simple objects had higher capacities and lower cerebral blood flow velocity than complex objects. Other working memory systems were not found to have an effect on performance.
8

Effects of Signal Modality and Event Asynchrony on Vigilance Performance and Cerebral Hemovelocity

Shaw, Tyler H. 02 October 2006 (has links)
No description available.
9

Metodología para el diseño riguroso de procesos químicos. Modelos híbridos: simulación-optimización

Navarro Amorós, Miguel Ángel 11 October 2013 (has links)
No description available.
10

Optimisation d'un schéma de codage d'image à base d'une TCD. Application à un codeur JPEG pour l'enregistrement numérique à bas débit

AMMAR, Moussa 14 January 2002 (has links) (PDF)
Nous considérons dans cette thèse le problème dotpimisation dun schéma de codage/décodage JPEG et le post-traitement de réduction des effets de blocs dans les images codées par JPEG.<br />Nous proposons tout dabord le filtrage de Wiener comme optimisation du banc de filtres de synthèse pour une distorsion minimale et nous cherchons par la suite une quantifcation optimisée. Lalgorithme itératif A1 réalise une optimisation conjointe des quantificateurs et du banc de filtres de synthèse. Les résultats experimentaux sur quelques images montrent que le gain total en terme de PSNR peut atteindre 1,36dB et les améliorations visuelles confirment ces résultats.<br />Enfin, nous proposons une nouvelle technique de réduction des effets de blocs basée sur la minimisation de lénergie haute fréquence du bruit de quantification. Lévaluation de lalgorithme B1montre une diminution des effets de blocs, et de nombreuses illustrations permettent dappréhender visuellement les performances de cette méthode.

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