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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

Engineering aspects of photogrammetric plate measurements, including the development of a novel interferometer

Severn, Ian January 1993 (has links)
Two different factors involved in the measurement of photogrammetric plates have been studied. A novel interferometer designed to monitor the position of a microscope stage, to be used to measure photogrammetric plates, has been built. The prototype instrument is able to give the position of the stage with a maximum error of less than 200nm. An algorithm has been developed for a motor driven x-y microscope that is able to search a photographic plate automatically for targets, and record their positions. In a trial survey this system was able to measure the positions of the targets on the plates with an uncertainty of approximately 2gm. This result is comparable with the precision that a human operator could achieve using the same equipment, but without the fatigue effect associated with visual observation. Virtually no human interaction is necessary for the system to function.
2

Application of acoustic emission sensing for the non-destructive evaluation of advanced composite materials

Baillie, Paul W. R. January 1999 (has links)
To evaluate the state of health of the composite, a real-time, in-situ acoustic emission (AE) damage detection system has been developed, where the monitoring of AE activity emitted from within a carbon/epoxy composite material (CFRP) is achieved using an all-fibre Mach-Zehnder interferometric sensor. The basic Mach-Zehnder configuration was modified to achieve the sensitivity needed to detect the low amplitude signals associated with AE. An active homo dyne feedback loop was employed to maintain quadrature, whereas polarisation controllers ensured that the state of polarisation of the guided beams were equal. Two additional components were included in the AE detection system; fibre collimators and a demountable composite test section. The fibre collimators adjusted the optical path length in one of the arms of the interferometer to help maintain system sensitivity from test to test. The demountable test section ensured ease of testing, without the need for continual fusion splicing. The characterisation of the fibre optic sensor was achieved by an analysis of its response to known acoustic disturbances. The fibre optic sensors response to continuous and transient acoustic excitation sources demonstrated the feasibility of using an embedded fibre optic Mach-Zehnder interferometric sensor for the evaluation of composite materials. The sensor's potential for non-destructive evaluation (NDE) was investigated by placing CFRP specimens with the embedded sensors under sufficient tension to cause damage. Signal analysis was performed on the detected AE data, using the time domain parameters and the cumulative event count. The change in the slope of the cumulative count curve coincided with the point where the accumulated damage seriously compromised the structural integrity of the sample. As a damage detection system the fibre optic sensor was adequate, however, the correlation of the time domain parameters with specific damage mechanisms proved inconclusive. Specially designed samples were manufactured to help the fibre optic sensor differentiate between mechanisms. Fibre optic sensor component failure resulted in the testing and analysis using the piezoelectric transducer only. Amplitude and frequency distribution analysis of the piezoelectrically detected signals from these specially designed composite samples was attempted. From the results, it was evident that a correlation could be made between some of the damage mechanisms and the detected AE signals. However, it was apparent that a mixing of distribution occurred in some of the tests. Despite this, the results obtained using the piezoelectric transducer highlighted the benefits of attempting these specially designed tests in future fibre optic sensor work.
3

Quantification of variation in biological input materials and its effect on manufacture and process control

Thurman-Newell, Jamie A. January 2017 (has links)
Currently cellular therapies, such as hematopoietic stem cell transplantation (HSCT), are produced at a small scale on a case-by-case basis, usually in a clinical or near-clinical setting. Meeting the demand for future cellular therapies will require a robust and scalable manufacturing process that is either designed around or controls the variation associated with biological starting materials. Understanding variation requires both a measure of the allowable variation (that does not negatively affect patient outcome) and the achievable variation (with current technology). The prevalence of HSCT makes it an ideal case study to prepare for more complex biological manufacturing with more challenging regulatory classifications.
4

Sächsisches Geometriesymposium 2020: Tolerierung | Fertigung | Messtechnik | Daten ; Tagungsband

Gröger, Sophie, Weißgerber, Marco 12 March 2020 (has links)
Das Sächsische Geometriesymposium versteht sich als eine interdisziplinäre Plattform geometriebezogene Themen in wissenschaftlichen Beiträgen vorzustellen. Aktuelle Forschungsergebnisse zur eindeutigen Beschreibung der Funktion von Bauteilen, über die geometriebezogene Bewertung von Fertigungstechnologien bis zur Qualifizierung von Messfahren werden präsentiert und mit Blick auf zukünftige Herausforderungen der Produktionstechnik bezüglich Digitalisierung und prozessübergreifender Ansätze diskutiert. Das Symposium führt die lange Tradition des Internationalen Oberflächenkolloquiums in neuem Format und in akademischer Gemeinschaft der vier Lehrstühle in Chemnitz, Zwickau, Mittweida und Dresden im Fachgebiet Fertigungsmesstechnik in Sachsen fort. / The Saxon Symposium on Geometry is an interdisciplinary network for scientific researchers on geometry related subjects. Recent research on the specification of functional characteristics, the geometry related assessment of manufacturing technologies and measurement methods is discussed with regard to future challenges like digitization or global process approaches. The symposium carries on with the tradition in Saxony and the former International Colloquium on Surfaces. The new format takes place in cooperation of the four production metrology chairs of Saxony’s universities in Chemnitz, Zwickau, Mittweida and Dresden.

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