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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.
121

Defect and thickness inspection system for cast thin films using machine vision and full-field transmission densitometry

Johnson, Jay Tillay 17 November 2009 (has links)
Quick mass production of homogeneous thin film material is required in paper, plastic, fabric, and thin film industries. Due to the high feed rates and small thicknesses, machine vision and other nondestructive evaluation techniques are used to ensure consistent, defect-free material by continuously assessing post-production quality. One of the fastest growing inspection areas is for 0.5-500 micrometer thick thin films, which are used for semiconductor wafers, amorphous photovoltaics, optical films, plastics, and organic and inorganic membranes. As a demonstration application, a prototype roll-feed imaging system has been designed to inspect high-temperature polymer electrolyte membrane (PEM), used for fuel cells, after being die cast onto a moving transparent substrate. The inspection system continuously detects thin film defects and classifies them with a neural network into categories of holes, bubbles, thinning, and gels, with a 1.2% false alarm rate, 7.1% escape rate, and classification accuracy of 96.1%. In slot die casting processes, defect types are indicative of a misbalance in the mass flow rate and web speed; so, based on the classified defects, the inspection system informs the operator of corrective adjustments to these manufacturing parameters. Thickness uniformity is also critical to membrane functionality, so a real-time, full-field transmission densitometer has been created to measure the bi-directional thickness profile of the semi-transparent PEM between 25-400 micrometers. The local thickness of the 75 mm x 100 mm imaged area is determined by converting the optical density of the sample to thickness with the Beer-Lambert law. The PEM extinction coefficient is determined to be 1.4 D/mm and the average thickness error is found to be 4.7%. Finally, the defect inspection and thickness profilometry systems are compiled into a specially-designed graphical user interface for intuitive real-time operation and visualization.
122

Automatic image analysis for decision support in rheumatoid arthritis and osteoporosis

Kälvesten, Johan January 2015 (has links)
Low-energy trauma and fragility fractures represent a major public health problem. The societal cost of the fragility fractures that occurred in Sweden 2010 has been estimated at €4 billion. In rheumatoid arthritis (RA), patient outcomes have improved greatly in recent years. However, the therapeutic decision making is still hampered by a lack of effective validated biomarkers. The cost of RA in Sweden 2010 has been estimated at €600 million, of which biologic drugs was €180 million. Digital X-ray radiogrammetry (DXR) is a method to measure bone mineral density (BMD) in the metacarpals of the hand. It can be applied opportunistically in several workflows where a person is already at an X-ray machine, including fracture repositioning follow up, mammography screening and hand imaging in RA. This thesis explored DXR-BMD as a marker to identify individuals who would benefit from anti-osteoporotic treatment, change rate of DXR-BMD as a biomarker in RA and under what conditions historical X-ray images can be used to estimate DXR-BMD. An automated method for measurement of joint space width in metacarpophalangeal and interphalangeal joints was also developed and evaluated as a biomarker in RA. Low DXR-BMD was predictive for hip fractures and predicted fragility fractures to a comparable degree as other BMD measurement sites. Rapid decrease of DXR-BMD was a strong and independent predictor for progression of radiographic damage in RA when manual radiographic progression scores were not available. Change of metacarpal joint space width was a statistically significant but weak predictor of joint space narrowing score progression. Guidelines and considerations for use of historical X-ray radiographs for DXR-BMD measurements in clinical trials have been developed and published.
123

Wood fibre properties and their application to tree-ring studies in British Columbia

Wood, Lisa June 25 April 2012 (has links)
Examination of the relationship between wood properties such as density, cell diameters and climate provides the opportunity to develop long-term climate and mass balance proxies, and is a key component to understanding when and how wood develops through time. This research sought to: create multi-proxy models to represent long-term changes in the climate-mass balance relationships at Place Glacier, and to describe glaciological changes in Mount Revelstoke and Glacier National Parks, British Columbia; use multiple wood properties to develop intra-annual climate records for tree-ring sites from the southern and northern interior regions of British Columbia; and, use climate as an indicator of wood quality by identifying historical climate impacts on wood development over time. Tree-ring samples from hybrid interior spruce (Picea glauca (Moench) Voss x engelmannii (Parry)) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were collected in north-central British Columbia; interior spruce, Douglas-fir, and subalpine fir (Abies lasiocarpa (Hooker) Nuttall) were collected from trees in the Pemberton area of British Columbia, and Engelmann spruce (Picea engelmannii Parry ex. Engelmann), subalpine fir, and mountain hemlock (Tsuga mertensiana Bongard Carrière) were collected from trees located within Glacier and Mt. Revelstoke National Parks. Tree-ring chronologies were constructed using standard ring width measurement techniques, densitometric methodologies, and using SilviScan technology. Relationships among the regional climate, snowpack, mass balance and various wood chronologies were identified and used as a basis for reconstructing proxy climate and mass balance data. A proxy snowpack record for Tatlayoko Lake was reconstructed using mean density and ring width chronologies. Maximum density and ring width chronologies were used to reconstruct winter and summer mass balance records for Place Glacier. Place Glacier was found to respond negatively to continental summer temperature regimes and positively to winter coastal precipitation events. A proxy record of maximum summer temperature was reconstructed for Revelstoke using maximum density and ring width chronologies; while maximum cell-wall thickness was used to reconstruct total August precipitation, and February snowpack from Golden was reconstructed from subalpine fir and mountain hemlock ring-width chronologies. Mass balance for glaciers in the Columbia Mountains was reconstructed using a combination of ring width, maximum density and maximum cell-wall thickness chronologies. The proxy mass balance reconstruction shows a general decline in ice mass over the time span of the net balance reconstruction. Two intra-annual proxy climate records were created for northern British Columbia. Mean June and mean July-August temperature chronologies were reconstructed for Smithers using ring width and maximum density, and for Fort St. James total May-June and July-August precipitation records were reconstructed using ring width, minimum density, and maximum cell-wall thickness. Wood parameters, including density, cell-wall thickness, microfibril angle, and cell diameter in Douglas-fir and interior spruce were reconstructed at five sites across British Columbia using temperature and precipitation data from local climate stations. Maximum cell-wall thickness was shown to be one of the most robust wood parameters to predict using temperature variables. Using a variety of tree-ring characteristics for time series reconstruction provides an opportunity to create multivariate models with greater predictive capabilities that correspond more closely to observed data sets, thereby allowing dendroclimatologists to predict climate data trends more robustly. Because individual wood parameters form at different times throughout the growing season in response to distinct seasonal climates, multiple proxy models allow for the development of intra-annual proxy climate and glaciological records. / Graduate
124

Diabetic osteopathy : a study in the rat /

Ahmad, Tashfeen, January 2003 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.
125

Spectroscopic instrumentation for process analytical chemistry /

Aldridge, Paul K. January 1991 (has links)
Thesis (Ph. D.)--University of Washington, 1991. / Vita. Includes bibliographical references (leaves [131]-137).
126

Retinol intake, bone mineral density and falls in elderly women

Gramer, Carrie M. January 2004 (has links)
Thesis (M.S.)--Oregon State University, 2003. / Includes bibliographical references (leaves 53-56). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.
127

Variance in percent body fat between and within families as measured by dual-energy X-ray absorptiometry /

Kelsey, Laurel Anne, January 2004 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Exercise Sciences, 2004. / Includes bibliographical references.
128

The utility of the Modifiable Activity Questionnaire for assessing the relationship between physical activity and bone density in children and adolescents

Snook, Theresa J., January 2002 (has links)
Thesis (M.S.)--Wake Forest University. Dept. of Health and Exercise Science, 2002. / Vita. Includes bibliographical references (leaves 54-63).
129

Retinol intake, bone mineral density and falls in elderly women

Gramer, Carrie M. January 2004 (has links)
Thesis (M.S.)--Oregon State University, 2003. / Includes bibliographical references (leaves 53-56).
130

A comparison of bone mineral density in Division I and Division III female gymnasts

Salacinski, Amanda. January 2002 (has links)
Thesis (M.S.)--Springfield College, 2002. / Includes bibliographical references.

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