• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 74
  • 14
  • 11
  • 8
  • 6
  • 5
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 138
  • 24
  • 23
  • 15
  • 14
  • 14
  • 12
  • 12
  • 11
  • 11
  • 10
  • 9
  • 9
  • 8
  • 8
  • 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

Belysningsnivåer vid receptionsdiskar / Illumination levels at reception desks

Berg, Therese, Siljeskog, Adam January 2014 (has links)
Detta examensarbete undersöker hur belysningen vid receptionsdiskar faktiskt serut och hur personalen som arbetar där upplever den. Syftet med examensarbetetär att identifiera om det finns anledning att förändra de riktlinjer och rekommendationersom ställs på belysning på och omkring receptionsdiskar. På hotellen idag är oftast miljöerna dämpade och varierande då hotellens syfte äratt skapa en upplevelse för gästerna. Det har väckt ett intresse hos oss att undersökareceptionsdisken som är en viktig plats på hotellen. Vi har jämfört ”Ljus ochRums” rekommendationer (SIS, 2011) med faktiskt uppmätta ljusnivåer i fyra receptionsdiskaroch personalens upplevelse av hur det påverkar hur de kan utförasina dagliga arbetsuppgifter. De metoder vi har använt är ljusmätning, jämnhetsberäkning, visuell analys ochenkätundersökning. Ljusmätningarna utfördes på fyra olika hotell i Göteborg.Frågeformuläret vände sig till personalen på hotellen och handlade om deras upplevelseav ljuset på och omkring receptionsdisken. För att få en uppfattning ochövergripande förståelse utfördes en visuell analys på hotellen. Majoritet av personalen anser att belysningen var tillräcklig för att utföra sina arbetsuppgifter.Det är tydligt att ljuset uppfattas olika på de fyra receptionsdiskarnaberoende på hur hotellet är utformat och designat. / The purpose of this study is to identify if there is reason to change the requirementsand recommendations for illumination in reception desks areas. This studyexamines how lighting in reception desks areas actually is and how the staff perceivesthe lighting. Hotels today usually have subdued environments that vary according to the typeof experience intended for their guests. Our interest has been to explore the receptiondesks area as an important and separate element within the hotel. We havecompared “Ljus och Rum” recommendations (Swedish Standards Institute [SIS],2011) with actual measured light levels for four reception desks areas and examinedhow the staff perceives how the lighting affects their performance of dailytasks. The methods we have used are light measurement, evenness calculations, visualanalysis and surveys. Lighting measurements were performed at four differenthotels in Gothenburg. The questionnaire was directed to the hotel staff in order toascertain their perception of the lighting in and around the reception’s desks area.In order to get an impression of and gain an overall understanding for the lighting,a visual analysis was done at each hotel. The majority of the staff considers the lighting sufficient to perform their duties.It is clear that the lighting is perceived differently in each of the four hotels, dependingon how each hotel is formed and how the lighting is designed.
32

Performance analysis and improvement of edge emitting semiconductor laser diodes for optical communications

Rashed, Atef Mahmoud Khalil January 2001 (has links)
No description available.
33

Identification et validation fonctionnelle de gènes candidats contrôlant la composition de la cuticule chez le fruit de tomate / Identification and functional validation of candidate genes controlling the composition of the tomato fruit cuticle

Petit, Johann 17 December 2013 (has links)
La cuticule, une matrice lipidique extracellulaire constituée de cires et d’un squelette de cutine, est la barrière de défense la plus externe des plantes face à leur environnement. Elle intervient dans de nombreuses propriétés agronomiques comme la conservation post récolte, les propriétés mécaniques ou bien l’aspect du fruit, dont la brillance. Afin d’isoler des mutants de cuticule, le criblage d’une collection de mutants EMS de tomate a été entrepris, en se basant sur la brillance des fruits, conduisant à la sélection de 24 mutants. Chez ceux-ci, des analyses biochimiques ont montré de fortes variations de charge et de composition de la cuticule, notamment chez les mutants de cutine. La caractérisation de 4 mutants remarquables a été entreprise afin d’identifier les mutations responsables des phénotypes de brillance. Le mutant le plus affecté, présentant une charge en cutine réduite de 85% par rapport au type sauvage, a révélé une mutation du gène SlGDSL2 codant pour une acylhydrolase à motif GDSL, responsable de la polymérisation de la cutine. Afin d’étudier la formation et la régulation de la cutine, la suite du travail a consisté à obtenir et à caractériser des simples et des doubles mutants affectés dans la synthèse des monomères de cutine, le transport apoplastique et la polymérisation de la cutine. / The cuticle, an extracellular lipid matrix consisting of waxes and of a cutin skeleton is the outermost plants protection barrier against their environment. The cuticle is involved in many agronomic traits such as post-harvest storage, biomechanical or fruit appearance properties like surface brightness. In order to isolate cuticle mutants, the screening of an EMS tomato mutants collection has been undertaken, based on fruit brightness, leading to the selection of 24 mutants. Biochemical analyzes have shown wide variations in cuticle loads and compositions, especially in cutin mutants. The characterization of 4 remarkable mutants was undertaken to identify the mutations responsible for brightness phenotypes. The most affected mutant shows a cutin load reduced by 85% compared to the wild type, and is due to a mutation in the SlGDSL2 gene, encoding a GDSL-motive acylhydrolase enzyme, responsible for the cutin polymerization. In order to further study the cutin formation and regulation, the next work was to obtain and characterize single and double mutants affected in cutin monomer synthesis, apoplastic transport and cutin polymerization.
34

Brightness Contrast of Solar Magnetic Elements Observed by Sunrise

Kahil, Fatima 01 March 2019 (has links)
No description available.
35

Análises dos parâmetros de cultivo da microalga Chlorella vulgaris / Analysis of the cultivation parameters of the microalga Chlorella vulgaris

Marino, Victor Fernandes 20 September 2018 (has links)
A produção de biocombustíveis a partir das microalgas vem se tornando promissora por ser uma fonte renovável, não poluente e por não competir com áreas de cultivo de alimentos. Devido à exaustão das fontes fósseis e à alta demanda por combustível de origem renovável e não poluente, as microalgas vêm despertando interesse nos cenários energético e ambiental. Por outro lado, existe um elevado custo no cultivo das mesmas, fazendo-se necessário estudos para desenvolvimento de novos reatores, meios de cultivos, técnicas de colheita, de extração de lipídios, transesterificação e também a implementação do conceito de biorrefinaria. Levando em conta o interesse crescente na utilização das microalgas como matéria prima na produção de biocombustíveis e a necessidade de estudos que torne o cultivo das microalgas em grande escala economicamente viável, esta pesquisa teve como objetivo determinar as melhores condições para o cultivo da microalga Chlorella vulgaris, buscando uma maior produtividade de biomassa e de lipídios. Os fatores avaliados foram: tempo de luminosidade, reciclo da biomassa após extração de lipídios e concentração de nutrientes (NaNO3, K2HPO4, KH2PO4 e glicerol) no meio de cultivo, em um arranjo ortogonal de Taguchi L8. De acordo com os resultados, identificou-se uma maior relevância, para a produtividade de biomassa, a utilização de glicerol e luminosidade (12 h), seguido do NaNO3 em alta concentração. A utilização de biomassa extraída mostrou-se inviável para o processo de cultivo, e a utilização de K2HPO4, KH2PO4 foram pouco influentes, porém essenciais. Paralelamente foi avaliado a viabilidade em se utilizar o efluente da Estação de Tratamento de Esgoto (ETE) da Escola de Engenharia de Lorena (EEL-USP) como meio de cultivo em um reator de PVC, construído para cultivo heterotrófico, no qual obteve-se uma alta produtividade de biomassa (0,20 g.L-1.d-1) e de lipídios (83,35 mg.L-1.d-1), se comparados a outros processos. / The production of biofuels from microalgae has become promising because it is a renewable, non-polluting source and because it does not compete with food growing areas. Due to the exhaustion of fossil fuel sources and the high demand of fuel from renewable and non-polluting origin, microalgae have been attracting interest in the energy and environmental scenarios. On the other hand, there is a high cost to cultivate microalgae, making necessary studies for the development of new reactors, culture media, harvesting techniques, lipid extraction, transesterification and also the implementation of the biorefinery concept. Taking the growing interest in the use of microalgae as a raw material in the production of biofuels and the need of studies to make large-scale microalgae cultivation economically viable, this research aimed to determination of the best conditions for the cultivation of microalga Chlorella vulgaris, seeking a higher productivity of biomass and lipids. The factors evaluated were: time of luminosity, biomass recycling after lipid extraction and nutrient concentration (NaNO3, K2HPO4, KH2PO4 and glycerol) in the culture medium using a orthogonal arrangement of Taguchi L8. According to the results, a greater relevance was identified for biomass productivity, the use of glycerol and luminosity (12 h), followed by NaNO3 in high concentration. The use of extracted biomass proved to be impractical for the process, and the use of K2HPO4, KH2PO4 was weak but essential. In parallel, the feasibility of using the effluent of the Effluent Treatment Plant (ETP) on Escola de Engenharia de Lorena (EEL-USP) as a culture medium for a PVC reactor, built for heterotrophic cultivation. It was obtained higger productivity of biomass (0.20 g.L-1.d-1) and lipids (83.35 mg.L-1.d-1) from it, if you compare to others process.
36

Liquid-Jet-Target Microfocus X-Ray Sources : Electron Guns, Optics and Phase-Contrast Imaging

Tuohimaa, Tomi January 2008 (has links)
This Thesis describes the development of an electron-impact microfocus x-ray source and its application for phase-contrast imaging. The source is based on a novel, liquid-jet target concept. Stable and continuous operation can be achieved at substantially higher electron-beam power densities than conventional solid target based systems. The maximum x-ray brightness can potentially be increased by a factor of 10-1000, which would provide significantly improved performance in applications such as imaging. In order to reach the high x-ray brightness, comparable performance from the electron gun is needed. A LaB6-cathode-based electron gun is analyzed in terms of achievable e-beam brightness and beam quality and is found capable to deliver power densities in the 10-100 MW/mm2 range using optimized electro-optics. A proof-of-principle microfocus source has been developed. Experiments show that the liquid-metal-jet target can be operated at more than an order of magnitude higher e-beam power densities than modern solid-metal targets. This brightness enhancement has been utilized to acquire in-line phase-contrast images of weakly absorbing objects. The source potentially enables the application of high-resolution phase-contrast x-ray imaging with short exposure times in clinics and laboratories. Different liquid-jet-target materials have been tested. The Sn-jet (Ka=25.3 keV) could be suitable for mammography, whereas the Ga-jet ((Ka=9.2 keV) may be utilized for x-ray diffraction studies. In addition, a non-metallic methanol jet has been the demonstrated in stable x-ray operation. All materials and compounds found in liquid form can, thus, potentially be used for electron-impact liquid-jet-target x-ray generation. Scaling to higher e-beam power density and x-ray brightness levels is discussed and is determined to be feasible. Potential difficulties, such as debris emission and instabilities of the x-ray emission spot, are investigated in some detail. Larger and/or faster jets could overcome the present limitations because of their inherently higher heat load capacities. Dynamic-similarity experiments show that liquid jets can in principle be operated in a stable manner at much higher speeds than previously shown. / QC 20100915
37

An investigation of accelerated brightness reversion of bleached slash pine kraft pulp.

Rollinson, Samuel Milton 01 January 1954 (has links)
No description available.
38

A study of the chemical recovery in the monosulfite pulping process.

Schelhorn, Frederick Bernard 01 January 1943 (has links)
No description available.
39

Optimal Analysis of pyramid-shaped microlens array

Chang, Yi-Wen 09 September 2009 (has links)
In this paper, we searched the parameter of BEF (Brightness enhancement film) using commercial FRED server for backlight module. The pattern analysis was carried out to understand its characteristic. The current structures used in LCD backlight are double-layer BEF. In addition, BEF of 3M takes the lion¡¦s share. But this may increase the thickness and cost of backlight module. In order to avoid those disadvantages, we tried to design single-layer BEF and characterize the effect through parameters study by using FRED software simulation. pyramid-shaped microlens array of BEF was constructed. Therefore, the effect of the variation of the structure parameters can be analyzed, such as prismatic degree (£c), prismatic structure on the brightness enhancement. It can be found from the result of simulation that the changes of the prismatic degree (£c) of 85 degree influence the brightness enhancement the most.
40

Reconstruction of the temperature profile along a blackbody optical fiber thermometer /

Barker, David G. January 2003 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2003. / Includes bibliographical references (p. 87-89).

Page generated in 0.0254 seconds