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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.
31

Heat Transfer in Brine Solutions at Supercritical Pressure

Johnson, Thomas G. 17 September 2015 (has links)
No description available.
32

Women in Wrestling Arenas: How Globalization, Socially Produced Spaces, and Commodification Impact their Portrayal and Empowerment Post Women's Revolution

Kohlmeyer, Collin 05 1900 (has links)
The Women's Revolution in 2015 has led to a drastic shift in the ways women are portrayed in professional wrestling. The Women's Revolution came as a result of the social unrest over the lack of time women were receiving on the televised shows. Where women's storylines had centered on their sexuality, they are now presented as equal to their male counterparts after the Women's Revolution. Through an exploration of concepts in globalization, commodification, and socially produced spaces, this research seeks to understand and contextualize the Women's Revolution, the degree to which the portrayed women's equality has been achieved, and the resulting impacts of the female superstars overall. I argue that that this "equality" has been achieved through inscribing the traditionally masculine qualities of wrestling to women, has resulted in an unequal distribution of opportunities to particular female superstars rather than equality for all women on the shows, and that phallocentric objectification of the female superstars still occurs in certain aspects of professional wrestling.
33

Production of radionuclides with medium energy protons with the emphasis on targetry

Vermeulen, Christiaan 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The facilities for radionuclide production at iThemba LABS have undergone a number of significant upgrades over the last decade in order to increase the production capacity and to diversify the product portfolio. Central to this effort is a new vertical beam target station (VBTS) and its associated targetry, designed and built to operate at higher proton beam intensities for the large-scale production of relatively long-lived, high-value radionuclides such as 22Na, 68Ge and 82Sr. Along with the VBTS, an existing smaller horizontal beam target station was adapted to accommodate targetry for 18F production, mainly to supply 18F-FDG for use in positron emission tomography (PET). The production capacity was further enhanced by means of a beam splitter to enable bombardments in two target stations simultaneously. This required new developments on several systems, e.g. beam diagnostics, control, interlocking and cooling. This project brings together a number of different aspects of the upgraded facilities as well as the associated research and development that enable the production of radionuclides in the medium energy region, up to approximately 70 MeV. Investigations were performed on the cooling of the interfacial windows between the cyclotron vacuum and the targets as well as the direct cooling of the targets themselves during intense proton bombardments. For this purpose, empirical as well as computational fluid dynamics (CFD) calculations were performed. In addition, the local radiation shield of the VBTS as well as the beam transport in some of the targetry was investigated by means of Monte Carlo radiation transport calculations. Excitation functions for the production of various radionuclides in the 66 MeV proton bombardment of 192Os, 159Tb, natGd, 155Gd, 152Gd, 93Nb, natZr and 89Y were measured and compared with theoretical predictions by means of statistical nuclear model calculations as well as the TENDL-2012 library. In particular, the production of 186Re, selected radioterbiums (149;152;155Tb) and radiozirconiums (88;89Zr) is of interest in existing and emerging diagnostic and therapeutic applications in nuclear medicine. A study on 28Mg production in the proton bombardment of natCl using stacked chloride targets was also performed at 200 MeV. This radionuclide is of interest as 28Mg is the only practical radiotracer of Mg. Finally, new targetry for the production of 18F was developed, modelled and optimized for the non-standard degraded beam employed in this particular case. / AFRIKAANSE OPSOMMING: Die fasiliteite vir die produksie van radionukliede by iThemba LABS is gedurende die afgelope dekade aansienlik opgegradeer om die produksiekapasiteit te verhoog en om die portfolio van produkte te diversifiseer. Sentraal tot hierdie poging is ’n vertikale-bundel skyfstasie (VBTS) wat gebou is om skywe met hoër intensiteit protonbundels te bombardeer ten einde relatief langlewende, hoë-waarde radionukliede op grootmaat te produseer, insluitende 22Na, 68Ge en 82Sr. Terselfdetyd is ’n bestaande, kleiner horisontale-bundel skyfstasie aangepas om skywe vir die produksie van 18F te huisves, meestal om 18FFDG vir positronemissietomografie (PET) te lewer. Die produksiekapasiteit is verder verhoog d.m.v. ’n bundeldeler sodat bundel gelyktyding aan twee skyfstasies gelewer kan word. Dit het ontwikkelingswerk vereis aan verskeie stelsels, insluitende diagnostiek, beheer, vergrendeling en verkoeling. Hierdie projek bring verskeie aspekte bymekaar t.o.v. die opgegradeerde produksiefasiliteite sowel as die geassosieerde navorsing en ontwikkeling benodig vir radionukliedproduksie in die middelenergiegebied tot ongeveer 70 MeV. Die verkoeling van die foelievensters tussen die vakuum van die siklotron en die skyfgerei is ondersoek sowel as die direkte verkoeling van skywe onder intense protonbombardement. Hierdie studie sluit beide empiriese sowel as numeriese vloeidinamika berekeninge in. Verder is die afskerming van die VBTS asook die bundeltransport in verskeie skywe ondersoek m.b.v. Monte Carlo stralingstransport berekeninge. Opwekkrommes vir die produksie van verskeie radionukliede met protongeïnduseerde reaksies tot en met 66 MeV op 192Os, 159Tb, natGd, 155Gd, 152Gd, 93Nb, natZr en 89Y is gemeet en vergelyk met statistiese kernmodel berekeninge sowel as die TENDL-2012 biblioteek. Die produksie van 186Re, verskeie radioterbiums (149;152;155Tb) en radiozirkoniums (88;89Zr) is van spesifieke belang vir bestaande en toekomstige diagnostiese en terapeutiese toepassings in die kerngeneeskunde. ’n Studie op die produksie van 28Mg in die bombardement van natCl met 200 MeV protone is ook onderneem. In hierdie ondersoek is ’n stapel chloriedskywe gebruik. Die 28Mg is van belang omdat dit die enigste Mg radioisotoop is wat geskik is as ’n radiospoorder van dié element. Laastens is nuwe skyfgerei vir die produksie van 18F ontwikkel, gemodelleer en geoptimiseer vir die nie-standaard afgeremde bundel wat benut word in hierdie geval.
34

Extending the validity range of the linear, fluid description of parametric instabilities in laser produced plasma

Machacek, A. C. January 2000 (has links)
No description available.
35

Measurement of ion and electron populations in laser produced plasmas by x-ray absorption spectroscopy

Hoarty, David John January 1998 (has links)
No description available.
36

High intensity laser interactions with sub-micron droplets

Mountford, Lorna Catherine January 1999 (has links)
No description available.
37

X-ray line transfer in rapidly expanding laser-produced plasmas

Patel, Pravesh K. January 1998 (has links)
No description available.
38

Quantitative spectroscopy of low temperature magnesium and titanium plasma plumes

Martin, Geoff W. January 1999 (has links)
No description available.
39

Avaliação das propriedades do concreto quando utilizado após o tempo máximo de mistura e transporte especificado pela NBR 7212 / Evaluation of Compressive Strength and Water Absorption of Concrete Used after the Maximum Time of Mixing and Transport Specified by NBR 7212

Polesello, Eduardo January 2018 (has links)
As propriedades requeridas em relação à resistência e à durabilidade de um concreto no estado endurecido estão diretamente ligadas às suas condições no estado fresco, sendo assim, etapas como processo de mistura, transporte, lançamento e adensamento do concreto devem ser adequadamente monitoradas e controladas ao longo do tempo, durante seu estado fresco. A norma brasileira NBR 7212 (ABNT, 2012), para execução de concreto dosado em central, estipula o tempo máximo para que o concreto seja completamente descarregado (aplicado) em 150 minutos. No entanto, em diversas situações práticas observam-se contratempos relacionados com atrasos na execução da obra ou no transporte para entrega do concreto, fazendo com que no momento de lançamento este concreto seja rejeitado em função do tempo decorrido entre o início da mistura dos materiais e a aplicação do concreto no canteiro de obra, além de apresentar considerável perda em sua trabalhabilidade. Porém, principalmente, em função de cronogramas de obras, de custo e da preocupação ambiental, fica clara a necessidade de alternativas que viabilizem sua utilização, garantindo as condições adequadas para lançamento e adensamento, sem que haja impactos negativos em suas propriedades finais. O objetivo desta pesquisa consiste na avaliação das propriedades mecânicas e de durabilidade do concreto, quando mantido em mistura prolongada e utilizado após esse tempo máximo de mistura e transporte especificado pela norma, a partir do primeiro contato do cimento com a água. Os concretos foram produzidos com dois tipos de cimento, CPIV e CPII, e seu abatimento foi mantido ao longo de 6 horas de mistura com a incorporação de aditivo superplastificante à base policarboxilato. Nesse estudo adotaram-se três relações a/c e a produção dos concretos foi realizada em laboratório e em condição real numa central dosadora de concreto. Os resultados obtidos, para os materiais e procedimento utilizados, avaliando o comportamento do concreto em relação ao módulo de deformação, calor de hidratação gerado, carbonatação e penetração de cloretos pela exposição à condição natural, mostram que não há perda no seu desempenho final, quando utilizado acima do tempo especificado por norma, adotando o procedimento de manutenção do abatimento com a incorporação de aditivo superplastificante à base de policarboxilato, conforme proposta deste estudo. Análises do comportamento reológico e microestruturais em pastas de cimento, com as mesmas características utilizadas na produção dos concretos, corroboram com os resultados obtidos. / The required properties in relation to the concrete strength and durability in the hardened state are directly linked to its fresh state conditions, thus, steps such as concrete mixing, transporting, launching and compacting must be properly monitored and controlled during this material production. The Brazilian Standard (NBR 7212/2012) for central mixed concrete stipulates as 150 minutes the maximum time for completely concrete discharging (applying). However, there are setbacks related to execution or transportation delays, resulting in workability loss, often causing this concrete rejection in building plants. Therefore, due to work schedules, cost and environmental concern, it is clear the need for alternatives that make feasible this concrete use, guaranteeing the appropriate launching conditions and densification, without negative impacts on its hardened properties. In this context, this research subject is to evaluate the concrete mechanical properties and durability, when kept in prolonged mixing conditions and used after the maximum mixing and transport time specified by the Brazilian standard. The concretes were produced with two kinds of Portland Brazilian cement, called CP IV e CP II, with fixed consistency and with polycarboxylate superplasticizer addition. Additionally, three water/cement ratios were analyzed in concretes mixed in the laboratory and central mixed conditions. In this research, where analyzed concretes with an overpass time of application, maintaining the consistency with superplasticizer addition. With the materials and procedures utilized, it was not observed loss on concrete performance related to the modulus of elasticity, hydration heat, carbonation and chloride penetration under natural exposure. The rheological and microstructural analysis in cement pastes, reproducing the concrete proprieties, corroborates with this conclusion.
40

Digitala läromedel i svenskundervisningen : En studie av svensklärares attityder till digital undervisningspraktik

Berg, Fredrik January 2018 (has links)
The purpose of this study is to investigate upper secondary school teachers’ perception of publisher produced digital tools within the frame of each teachers’ subject teaching in Swedish. The study questions following the issues: (1) what attitude do teachers have towards publisher produced digital tools within the field of their subject Swedish? (2) Which, if any, expectations from the principal/ school administration do the teachers have of using the publisher produced digital tool in their education? And (3) how is the publisher produced digital tool applied in the education? To answer these questions, semi-structured interviews were conducted with six upper secondary school teachers who, among other subjects, teach Swedish. This study relies on a phenomenographic method and the phenomenon is the publisher produced digital tool. The result shows that the six interviewed teachers use publisher produced digital tools between 10 and 20 percent of their lesson time in subject of Swedish. That low utilization can partially be explained by the teachers’ long tradition of constructing their own teaching materials. Another explanation could be that publisher produced digital tools are relatively new and that the teachers feel uncomfortable using them. The expectations from the principal/school administration about the teachers’ usage of these digital tools in their teaching is relatively low. Whether the usage of publisher produced digital tools is going to increase or not in the future is unknown – it is up to the teachers of Swedish to determine.

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