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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.
11

A method for the characterization of white spots in vacuum-arc remelted superalloys

Viosca, Alan Lee 30 July 2012 (has links)
Vacuum-Arc Remelting (VAR) is an important process for manufacturing Ti- and Ni-based superalloys. Currently, the sources and mechanisms behind microstructural anomalies produced in VAR superalloy ingots are not well understood. In order to help understand formation processes, a method of characterizing specific anomalies in VAR ingots is desired. This paper presents a method of characterizing the composition and morphology of anomalies in VAR alloy ingots using a combination of serial sectioning and X-ray fluorescence (XRF) energy dispersive spectroscopy (EDS) techniques. This process is demonstrated on a dirty white spot from an Alloy 718 sample. The white spot of interest was serial polished and 2-D XRF EDS maps were acquired at each polish depth. The EDS maps were then stacked to form a 3-D representation of the white spot. In addition, SEM and optical microscopy techniques were used to further characterize the composition and morphology of the dirty white spot. The dirty white spot is composed of both Ti-enriched and Nb-depleted regions. The 2-D EDS maps acquired with the XRF equipment provided adequate contrast for creating a 3-D representation of the Ti-rich region of the dirty white spot. However, contrast was not sufficient to create a 3-D representation of the Nb-depleted region. The XRF EDS equipment combined with SEM and optical microscopy techniques provided valuable information about the morphology and composition of the Alloy 718 dirty white spot. It is concluded that this dirty white spot was produced by fall-in from either the crown or shelf regions during the VAR process. / text
12

Optical biopsy systems using ultra-slim objectives for the diagnosis of breast cancer

Kyrish, Matthew 16 September 2013 (has links)
One in eight women in America will develop breast cancer at some point in their lives. Breast cancer is the second deadliest form of cancer for women in the United States. When a suspicious region of the breast is detected, the tissue is diagnosed by removing a sample, preparing an H&E section, and performing histopathology. This procedure is expensive, invasive, and can take days to return a diagnosis. An alternative to excision biopsies is to instead perform an optical biopsy. This work details endomicroscopes intended to perform optical biopsies in breast tissue. The work address two issues limiting current optical biopsy systems: insufficient resolution and inability to reject out of focus light. To improve the resolution of current endomicroscopes, ultra-slim objectives are developed using optical plastics and zero alignment fabrication techniques. These objectives can outperform current alternative endomicroscope objectives in terms of performance across the field of view and chromatic aberration correction, while remaining as narrow as a biopsy needle. Next, an endomicroscope which utilizes structured illumination to perform optical section is designed, tested, and evaluated on ex vivo breast biopsies. The new endomicroscope provides high contrast images by reducing out of focus background light. Finally, an achromatic, ultra-slim objective and the structured illumination endomicroscope are integrated to form an optical biopsy system with improved lateral resolution and axial response. This integrated system is a step forward for in vivo microscopy and cancer diagnoses.
13

Automating the process of dividing a map image into sections : Using Tesseract OCR and pixel traversing / Automatisering av processen att dela in en kartbild i sektioner : Med hjälp av Tesseract OCR och pixel traversering

Skoglund, Jesper, Vikström, Lukas January 2018 (has links)
This paper presents an algorithm with the purpose of automatically dividing a simple floor plan into sections. Sections include names, size and location on the image, all of which will be automatically extracted by the algorithm as a step of converting a simple image into an interactive map. The labels for each section utilizes tesseract-OCR wrapper tesseractJS to extract text and label location. In regards to section borders pixel traversing is employed coupled with CIE76 for color comparison which results in the discovery of size and location of the section. Performance of the algorithm was measured on three different maps using metrics such as correctness, quality, completeness, jaccard index and name accuracy. The metrics showed the potential of such an algorithm in terms of automating the task of sectioning an image. With results ranging between lowest percentage of 48% and highest of 100% on three different maps looking at correctness, quality, completeness, average jaccard index and average name accuracy per map.
14

The Temperature Dependence of Grain Boundary Complexion Transitions and Their Effect on the Grain Boundary Character and Energy Distributions

Kelly, Madeleine Nicole 01 August 2017 (has links)
No description available.
15

THREE-DIMENSIONAL ANALYSIS OF CONSTITUENT REDISTRIBUTION AND SWELLING IN A NEUTRON IRRADIATED U- 10 WT.% ZR FUEL USING FIB-SEM SERIAL SECTIONING

Nicole Rodriguez Perez (15354319) 27 April 2023 (has links)
<p>  </p> <p>Transition to a sustainable power grid entails the use of all net-zero carbon emission technology that is currently available. Liquid metal-cooled fast nuclear reactors (LMFRs) are technologies capable of competitively providing power while attaining sustainability and reliability. Uranium-zirconium metallic alloys have been proposed as LMFRs fuels based on the performance of the fuel in experimental scale reactors, achieving up to 20 at.% burn-up. The following phenomena affects the irradiation performance of U-Zr fuels: constituent redistribution, swelling, fuel-cladding mechanical interaction (FCMI), and fuel-cladding chemical interaction (FCCI). Further understanding of these phenomena, and development of predictive models requires data collection of variables such as composition, morphology of the redistribution regions, porosity distribution, porosity morphology, fission gas release, and the relation between local composition and porosity evolution. </p> <p>To achieve this, focused ion beam-scanning electron microscopy (FIB-SEM) serial sectioning was applied to specimens from the different compositional regions developed during constituent redistribution of a U-10 wt.% Zr fuel neutron irradiated to 5.7 at.% burn-up. High-resolution backscattered electron (BSE) micrographs, and energy dispersive spectroscopy (EDS) spectra were obtained for several sections of each specimen. Each section was analyzed to identify the microstructural and compositional evolution in the specimen volume. Three-dimensional porosity and phase volume distribution was obtained using image processing and three-dimensional object classification. The study revealed local segregation of phases within each of the regions, porosity distribution dependency on temperature and local composition, preferential porosity nucleation sites, porosity evolution trends, interconnectivity, possible sinks/nucleation sites for porosity and precipitates, as well as possible mechanisms for fission gas release.</p>
16

Development of an automated characterization-representation framework for the modeling of polycrystalline materials in 3D

Groeber, Michael Anthony 30 August 2007 (has links)
No description available.
17

Utvärdering av "dumpingmetoden" vid otillräckligt dehydrerade vävnadsprover / Evaluation of the “dumping method” for insufficiently dehydrated tissue samples

Mellbo, Johan, Müller, Alisha January 2019 (has links)
När ett vävnadspreparat har genomgått en otillräcklig dehydrering måste det åtgärdas innan provet kan gå vidare i den histotekniska processen. I dagsläget finns det två åtgärdande metoder på Patologilaboratoriet, Region Jönköpings län. Den ena metoden går ut på att provet placeras i smält paraffin för mer stadga. Den andra metoden går ut på att provet rehydreras för att sedan dehydreras på nytt. Syftet med denna studie var att utvärdera en tredje metod, ”dumpingmetoden” som går ut på att vävnadspreparaten dehydreras på nytt direkt utan att först bli rehydrerade.  Denna metod utförs i nuläget redan på vissa hud- och obduktionspreparat på Patologilaboratoriet. ”Dumpingmetoden” skulle kunna förenkla arbetet på laboratoriet då den är snabbare, kräver färre kemikalier och är automatiserad till skillnad från befintliga metoder. Resultaten från studien visade att ett otillräckligt dehydrerat vävnadspreparat aldrig kan bli lika bra som om det hade hanterats korrekt från början. Det är dock trots allt möjligt att åtgärda ett otillräckligt dehydrerat preparat i den graden att det blir bedömbart. ”Dumpingmetoden” förenklade snittningen av alla preparat som testades. Hos kolon- och tonsillpreparat verkade ”dumpingmetoden” ge bättre kvalitet av hematoxylin- och eosinfärgningen än de befintliga metoderna. För hudpreparat gav dock metoden där vävnadspreparat rehydrerats för att sedan dehydreras på nytt bäst kvalité av infärgningen. / A tissue that has been insufficiently dehydrated has to be fixed before it can continue through the histotechnological process. Currently, there are two established measures at the Pathology Laboratory, Department of Laboratory Medicine, Region Jönköping County. One of the methods is to put the sample in melted paraffin to give the tissue more support. The other method is to rehydrate the tissue followed by a new dehydration. The purpose of this study was to evaluate a third method called the “dumping method”. The “dumping method” involves a directly dehydration of the tissue, excluding rehydration. This method is currently being used on some of the skin and autopsy samples at the Pathology Laboratory. The “dumping method” would ease the work at the Laboratory since it is faster, requires fewer chemicals and can be automated, unlike the current available methods. The results from the study showed that an insufficiently dehydrated tissue can’t be restore to its original state. Never less it is possible to restore the tissue sufficiently for diagnosis. The “dumping method” eased the sectioning of all the tissue samples included in this study. For colon and tonsil tissues, the “dumping method” ensured higher quality of the haematoxylin and eosin staining than the current available methods. For skin tissues, however, the method of rehydration followed by a new dehydration resulted in the highest staining quality
18

Structured light for three-dimensional microscopy

Krzewina, Leo G 01 June 2006 (has links)
The conventional light microscope is an indispensable tool for many physical and life science applications, but is of limited usefulness for three-dimensional imaging due to its increasingly narrow depth of field at high magnifications. Focused regions may be obscured by defocused neighbors or noise from extraneous light sources and subsurface scattering. By rejecting light originating from outside the depth of focus it is possible to minimize these problems. When a contiguous series of such focused slices, or optical sections, are obtained along an axis of an extended object they may be combined to form a complete, focused three-dimensional surface image. Here, a variety of methods to obtain optical sections in a reflective setup are presented. The first employs an optical feedback loop through a spatial light modulator (SLM) to selectively illuminate focused regions. The SLM is a flexible electro-optical device that also allows (non-feedback) experiments of an intensity modulated light source resulting in illumination with a linear structure. This structured illumination microscopy is an established sectioning technique, which requires three frame captures per axial position. By developing a color grid and exploiting the red, green, and blue channels of a CCD camera, the three frames have been reduced to one. The speed increase comes at a cost and the limiting effects of chromatic aberration are discussed. Digital holography offers an alternative to axial scanning by allowing the surface to be reconstructed from a single exposure. Use of multiple wavelength illumination with this extended focus imaging is proposed and preliminary results are shown.
19

Polymer embedding for ultrathin slicing and optical nanoscopy of thick fluorescent samples / Polymereinbettung für die Anfertigung von Ultradünnschnitten und optische Nanoskopie an dichten fluoreszierenden Proben

Punge, Annedore 28 October 2009 (has links)
No description available.
20

Framing The Invisible:section As A Spatial Frame For A Reconsideration Of Architectural Representation

Alkan, Alper Semih 01 June 2004 (has links) (PDF)
This thesis is a critical reconsideration of the relationship of architectural production with its modes of representation. Historically, the representation of architecture has been signifying an interval where the displacement between the mental conception and its material expression has taken place. The group composed of plan, section and elevation is called orthographic set, which has been accepted as a universal code in architecture since it is attributed with the basic premise of its being objective and international. It is this attributed character of the drawings, which will be investigated in respect to the act of sectioning. Section displays an ambiguous character that it is the picture plane and the act of cutting at once. This study is a critical redefinition of section as a spatial act of framing. The construction of picture plane is discussed as a specific condition of framing, thus of sectioning. Like the specificity of the perspectival representation, the section constructs its own frame, in which the physical cut into the body of architectural object and its flattened spatial depth overlap. Therefore, section is redefined as the operation of a spatial framing, which rather hides than displays. It is in this hidden dimension that the epistemological value in architectural representation lies. The significance of the picture plane, that is the incision plane, is revealed by its relation to the constitution of perspective and projective drawings. The related concept of projection, whose mode strictly corresponds to the distance stimulated by the mode of projection, provides not only a critical distance but also brings about the operations to overcome that distance. In this respect, acknowledging section in architectural representation as a conceptual spatial frame, the study tries to reveal the inherent depth of the medium of representation, which is sometimes more promising than what is displayed in.

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