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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.
251

The Global Detrital Zircon Database: Quantifying the Timing and Rate of Crustal Growth

Voice, Peter James 28 May 2010 (has links)
Published detrital zircon geochronological data was compiled to form the Global Detrital Zircon Database (GDZDb). This database provides a reference block for provenance analysis by future detrital zircon geochronological studies. This project entailed three subprojects: 1. crustal growth/crustal recycling patterns, 2. a provenance study of the Triassic Dry Fork Formation of the Danville-Dan River Rift basin of Virginia and North Carolina, and 3. sample size issues in detrital zircon studies. The global detrital zircon age frequency distribution exhibits six prominent, statistically significant peaks: 3.2-3.0, 2.7-2.5, 2.0-1.7, 1.2-1.0, 0.7-0.5, and 0.3-0.1 Ga. These peaks are also observed when the data is sorted for continent of origin, the tectonic setting of the host sediment and for modern river sediments. Hf isotope model ages were also incorporated into the database where grains were dated with both U-Pb and Hf isotopes. The Hf isotope model ages suggest that the majority of detrital zircons U-Pb ages reflect crustal recycling events that generated granitic magmatism, as most grains exhibited Hf isotope ages that are much older than the corresponding U-Pb age. The Triassic Dry Fork Formation was sampled from a site in southern Virginia in the Danville-Dan River Basin. The detrital zircon age frequency distribution for this formation was strongly unimodal with a peak at 400-450 Ma and a paucity of Grenville-age zircons. Comparison of the Dry Fork sample to published east coast data and to the North American record (from the GDZDb) illustrate the unusual nature of the Dry Fork Formation sample. It is probable that older Grenville zircons were blocked from the rift valley by the rift shoulder. Using the GDZDb a study of sample size was conducted in order to estimate the best sample size to use when trying to constrain the maximum age of sedimentation of the host sediment. Rift basins and active margins exhibited smaller offsets from the youngest zircon grain age to host sediment maximum age than observed in samples from passive margins. This study recommends that at least 50 grains need to be age dated on average in order to best constrain the age of the host sediment. / Ph. D.
252

Shear Strengthening of RC Beams Using Externally Bonded and Anchored FRP U-wraps

D'Souza, Clinton January 2016 (has links)
Externally bonded FRP U-wraps are a common shear strengthening configuration for RC beams, however premature debonding of the wraps is a major problem, which limits the effectiveness and efficiency of the FRP strengthening. In this investigation a new π-shape carbon anchor was used to fasten the FRP U-wraps to the concrete in an attempt to prevent/delay debonding of the wraps and increase their effectiveness. Fourteen large scale rectangular beams with a 1900 mm span, 400 mm height, and 170 mm width were tested in three-point bending with various configurations of FRP shear strengthening. Shear pre-cracks were introduced in the beams at angles of 30 and 45 degrees in an attempt to control the inclination angle of the shear crack and determine its effect on the FRP shear resistance. The FRP shear strengthening configurations included un-anchored U-wraps, U-wraps with anchors, U-wraps with horizontal strips, and full wraps. The results showed that the use of a variable shear crack inclination angle in the CSA S806-12 (2012) standard led to overestimated shear resistance predictions for beams with a single shear crack, therefore a conservative 45 degree shear crack inclination is recommended for design. The use of the proposed carbon anchors resulted in a 74% increase in shear strength over the un-anchored U-wrapped beams, while only using half the amount of FRP. The use of the anchors also resulted in a 286% increase in the ultimate FRP strain over the un-anchored U-wraps, and allowed the FRP wraps to achieve 58% of their rupture strain. The use of horizontal strips provided similar results to the anchors and may be used as a less labour intensive alternative, but this issue needs further investigation. / Dissertation / Master of Applied Science (MASc) / Damaged or older reinforced concrete structures can be rehabilitated by using externally bonded fibre-reinforced polymer (FRP) sheets, which are bonded to the concrete surface using an epoxy adhesive. For the case of shear strengthening of beams, it is common for FRP sheets to be wrapped around the sides and bottom of the beam, resembling a U-shape. The problem with this configuration is that under high levels of load the FRP sheets tend to peel off the concrete surface (debonding). This limits the effectiveness of the rehabilitation and results in the inefficient use of the FRP. A new method for anchoring the FRP sheets to the concrete surface is investigated in this research study. The use of a new in-situ π-shape anchor shows promising results, as it delays debonding and provides a large increase in strength with less FRP needed.
253

Jämförelse av olika taktyper : Undersökning av sadeltak och pulpettak med hänsyn till ekonomi, U-värde, energi och miljöpåverkan

Thornhage-Ullnert, Joakim, Dinh, John January 2023 (has links)
Examensarbetet handlar om att jämföra två olika taktyper med hänsyn till ekonomi, U-värde, energi och miljöpåverkan. Taken skall belastas med samma karaktäristiska snölast. Taktyperna som jämförs är två parallelltak med vinklarna 3,6° och 10°, taktypen uteluftsventilerat sadeltak med vinkeln 27°. Syftet är att öka kunskapen hos konsumenter, arkitekter och konstruktörer för att enklare skräddarsy kundernas önskemål, där målet är att jämföra olika taktyper med olika lutningar med avseende på ekonomi, U-värde, energi och miljöpåverkan, när taken belastas med samma karaktäristiska snölast.   För att få fram ett resultat gjordes olika typer av beräkningar, så som konstruktions-, byggfysik-, energi-, klimat- och kostnadsberäkningar. Det gjordes även beräkningar på vilken mängd isolering som behövs för att U-värdet ska bli 75 % av BBR-kravet. Fuktkontroll gjordes efteråt, för att kontrollera om taken klarade av BBR-kravet gällande relativ fuktighet i konstruktionerna. Resultatet visade sig att parallelltaket med lutningen 3,6° gav bäst resultat gällande kostnader, koldioxidutsläpp och energi. Samma tak gav även bäst resultat gällande kostnad för uppförande inklusive material. Slutsatserna av det här examensarbetet visade att taktäckningen och längden på köldbryggor spelar stor roll ur det ekonomiska och klimatmässiga perspektivet.
254

Deep learning role in scoliosis detection and treatment

Guanche, Luis 29 January 2024 (has links)
Scoliosis is a common skeletal condition in which a curvature forms along the coronal plane of the spine. Although scoliosis has been long recognized, its pathophysiology and best mode of treatment are still debated. Currently, definitive diagnosis of scoliosis and its progression are performed through anterior-posterior (AP) radiographs by measuring the angle of coronal curvature, referred to as Cobb angle. Cobb angle measurements can be performed by Deep Learning algorithms and are currently being investigated as a possible diagnostic tool for clinicians. This thesis focuses on the role of Deep Learning in the diagnosis and treatment of Scoliosis and proposes a study design using the algorithms to continue to better understand and classify the disease.
255

An evaluation of U-Net’s multi-label segmentation performance on PDF documents in a medical context / En utvärdering av U-Nets flerklassiga segmenteringsprestanda på PDF-dokument i ett medicinskt sammanhang

Sebek, Fredrik January 2021 (has links)
The Portable Document Format (PDF) is an ideal format for viewing and printing documents. Today many companies store their documents in a PDF format. However, the conversion from a PDF document to any other structured format is inherently difficult. As a result, a lot of the information contained in a PDF document is not directly accessible - this is problematic. Manual intervention is required to accurately convert a PDF into another file format - this can be deemed as both strenuous and exhaustive work. An automated solution to this process could greatly improve the accessibility to information in many companies. A significant amount of literature has investigated the process of extracting information from PDF documents in a structured way. In recent years these methodologies have become heavily dependent on computer vision. The work on this paper evaluates how the U-Net model handles multi-label segmentation on PDF documents in a medical context - extending on Stahl et al.’s work in 2018. Furthermore, it compares two newer extensions of the U-Net model, MultiResUNet (2019) and SS-U-Net (2021). Additionally, it assesses how each of the models performs in a data-sparse environment. The three models were implemented, trained, and then evaluated. Their performance was measured using the Dice coefficient, Jaccard coefficient, and percentage similarity. Furthermore, visual inspection was also used to analyze how the models performed from a perceptual standpoint. The results indicate that both the U-Net and the SS-U-Net are exceptional at segmenting PDF documents effectively in a data abundant environment. However, the SS-U-Net outperformed both the U-Net and the MultiResUNet in the data-sparse environment. Furthermore, the MultiResUNet significantly underperformed in comparison to both the U-Net and SS-U-Net models in both environments. The impressive results achieved by the U-Net and SS-U-Net models suggest that it can be combined with a larger system. This proposed system allows for accurate and structured extraction of information from PDF documents. / Portable Document Format (PDF) är ett välfungerande format för visning och utskrift av dokument. I dagsläget väljer många företag därmed att lagra sina dokument i PDF-format. Konvertering från PDF format till någon annan typ av strukturerat format är dock svårt, och detta resulterar i att mycket av informationen i PDF-dokumenten är svårtillgängligt, vilket är problematiskt för de företag som arbetar med detta filformat. Det krävs manuellt arbete för att konvertera en PDF till ett annat filformat - detta kan betraktas som både ansträngande och uttömmande arbete. En automatiserad lösning på denna process skulle kunna förbättra tillgängligheten av information för många företag. En stor mängd litteratur har undersökt processen att extrahera information från PDF-dokument på ett strukturerat sätt. På senare tid har dessa metoder blivit starkt beroende av datorseende. Den här forskningen utvärderar hur U-Net-modellen hanterar segmentering av PDF dokument, baserat på flerfaldiga etiketter, i ett medicinskt sammanhang. Arbetet är en utökning av Stahl et al. forskning från 2018. Dessutom jämförs två nyare utökade varianter av U-Net-modellen , MultiResUNet (2019) och SS-U-Net (2021). Utöver detta så utvärderas även varje modell utefter hur den presterar i en gles datamiljö. De tre modellerna implementerades, utbildades och utvärderades. Deras prestanda mättes med hjälp av Dice-koefficienten, Jaccard-koefficienten och procentuell likhet. Vidare så görs även en visuell inspektion för att analysera hur modellerna presterar utifrån en perceptuell synvinkel. Resultaten tyder på att både U-Net och SS-U-Net är exceptionella när det gäller att segmentera PDF-dokument i en riklig datamiljö. SS-U-Net överträffade emellertid både U-Net och MultiResUNet i den glesa datamiljön. Dessutom underpresterade MultiResUNet signifikant i jämförelse med både U-Net och SS-U-Net modellen i båda miljöerna. De imponerande resultaten som uppnåtts av modellerna U-Net och SS-U-Net tyder på att de kan kombineras med ett större system. Detta föreslagna systemet möjliggör korrekt och strukturerad extrahering av information från PDF-dokument.
256

Isotope and Trace Element Investigation of Magmatic Processes and Timescales in the Azores

Watanabe, Shizuko 10 December 2010 (has links)
No description available.
257

Investigating Mechanisms of Glioma Cell Migration Within A 3D Biomimetic Microenvironment

Powell, Amanda Jean 22 May 2014 (has links)
No description available.
258

DIFFERENTIATION OF U-937 MONOCYTES TO MACROPHAGE-LIKE CELLS POLARIZED INTO M1 OR M2 PHENOTYPES ACCORDING TO THEIR SPECIFIC ENVIRONMENT: A STUDY OF MORPHOLOGY, CELL VIABILITY, AND CD MARKERS OF AN IN VITRO MODEL OF HUMAN MACROPHAGES

Abdulhadi, Fatma Husien S. 30 May 2014 (has links)
No description available.
259

Flanging and Bending of Advanced High Strength Steels

Srinivasan, Ganapathy January 2014 (has links)
No description available.
260

Framtidens Teater finns inte. En beskrivning av ett icke-linjärt projektarbete

Frost, Elin January 2009 (has links)
This is a non-traditional examination paper written after three years of studies at Malmö University and the Kaospilot Program. It is written in Swedish and in the spring of 2009. It describes a non-linear project based on a process-orientated theory called Theory-U by Otto C. Scharmer (2009). The project aims to investigate the changing conditions of Stage Theatre and deals with non-linearity as phenomena. As a result of Theory-U combined with a very personal approach, part of the project is reaching out to explore collective consciousness. The World Café model (Brown, Isaacs 2003) is chosen as a method for creating creative fields over a couple of linked dinner dialogues. There is no real conclusion in this paper. Instead five perspectives are presented in the last chapter with hopes of giving some nourishment to the field of performing arts. This paper will not provide final answers or any kind solid truth, instead it will give you some philosophical and personal perceptions of the Now.

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