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1
Sherwood, Nicholas. "An IPsec Compatible Implementation of DBRA and IP-ABR". Digital WPI, 2005. https://digitalcommons.wpi.edu/etd-theses/738.
Testo completoAbstract (sommario):
Satellites are some of the most difficult links to exploit in a Quality of Service (QoS) sensitive network, largely due to their high latency, variable-bandwidth and low-bandwidth nature. Central management of shared links has been shown to provide efficiency gains and enhanced QoS by effectively allocating resources according to reservations and dynamic resource availability. In a modern network, segregated by secure gateways and tunnels such as provided by IPsec, central management appears impossible to implement due to the barriers created between a global Dynamic Bandwidth Resource Allocation (DBRA) system and the mediators controlling the individual flows. This thesis explores and evaluates various through-IPsec communications techniques aimed at providing a satellite-to-network control channel, while maintaining data security for all communications involved.
2
Bohlen, Brandon Scott. "PECVD grown DBR for microcavity OLED sensor". [Ames, Iowa : Iowa State University], 2007.
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3
Horowitz, Luke. "Adaptation of VT-Dbr Lasers for LIDAR". DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1902.
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Vernier Tuned Distributed Bragg Reflector (VT-DBR) lasers have had great success in the field of Swept-Source Optical Coherence Tomography (SS-OCT) due to their continuous and nearly 40 nm wavelength tuning range in a single longitudinal mode. Fast sweeps allow for real time imaging with micrometer resolution at a distance of a few centimeters. While this laser has proven quite useful as a medical imaging tool via OCT, it has yet to similarly prove itself for general light detection and ranging (LIDAR) applications due to range limitations that arise from a finite laser coherence length. The goal of this thesis is to explore LIDAR applications for VT-DBR lasers and how to improve VT-DBR performance for LIDAR. In the scope of this work, LIDAR is laser imaging at tens or hundreds of meters with a resolution finer than 10cm. In order to achieve this kind of LIDAR performance with a VT-DBR laser, the laser must have a linewidth less than 1MHz over a tuning range of around 10GHz. This thesis outlines two methods towards this goal. The bulk of this work is dedicated to looking for and characterizing VT-DBR tuning paths with fundamentally narrow linewidth using microampere currents in both forward and reverse bias conditions. The second part of this thesis is a preliminary design of an optical frequency-locked loop to reduce laser phase noise, which subsequently reduces the laser linewidth.
By tuning with small currents in the forward bias condition, nearly the entire range of laser wavelengths could be tuned to, but areas of narrow linewidth were both sparse and very sensitive to any change in bias. The reverse bias case showed limited but continuous tuning with increased reverse current magnitude. In this reverse biased photo-detector mode the laser exhibited narrower linewidth less than 15MHz, with the linewidth at intrinsically narrow levels when all three sections reverse biased. Also promising was a subset of reverse bias conditions that only used a variable resistance across a laser section with no externally applied bias. This resistance tuning method gave a tuning range of more than 7GHz while maintaining an intrinsically narrow linewidth.
The optical frequency-locked loop was able to achieve DC frequency locking but unable to reduce laser linewidth. More work needs to be done to achieve enough phase noise reduction to see an appreciable reduction in linewidth.
4
Hett, Anne. "Studies on the metabolism of retained and excised introns in human cells". Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/10515.
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In eukaryotes the coding regions of most genes are interrupted by introns that must be removed by splicing to form a coding mRNA. However, while the splicing mechanism has received a lot of attention, much less is known about the metabolism of introns. This is partly due to the difficulties in studying introns as both aberrantly spliced transcripts and spliced introns are rapidly degraded. In this study, I have analysed intron metabolism in two respects: first I have investigated how introns are degraded following the completion of splicing. Second, I investigate the fate of transcripts, in which introns are retained due to splicing failure. In order to study the degradation of introns following splicing, I performed siRNA mediated knock down of the debrancing enzyme (Dbr1). Following splicing, introns are present in a circular lariat structure and Dbr1 is the enzyme thought to be responsible for opening this. Indeed, I found that knockdown of Dbr1 increased the amount of stabilised introns. Interestingly, introns were found to be stabilised in the cytoplasm and not in the nucleus as expected, even though immunofluoresence showed that Dbr1 is clearly nuclear. However, western blot analysis localised Dbr1 in the cytoplasm. Further investigation showed widely used methods to separate nuclear and cytoplasmic fractions are prone to generating artefacts which result in nucleoplasmic proteins delocalised to the cytoplasm. This finding may prevent future misinterpretation of data obtained by these methods. To investigate splicing failure, it was necessary to generated a sufficiently large pool of unspliced transcripts. To do this I used antisense morpholinos (AMOs) that bind to specific snRNAs (small nuclear RNAs). They are designed to block interaction surfaces that are important for splicing. Using this approach, I investigated the localisation of RNA transcripts and selected RNA processing and degradation factors in normal conditions and where splicing was inhibited. When splicing is inhibited I found splicing factors and unspliced, polyadenylated RNA localising to nuclear, splicing speckle marker SC35 positive speckles. I further discovered that for RNA to localise to nuclear speckles, polyadenylation and RNA cleavage are essential, indicating that SC-35 speckles might sequester unspliced transcripts preventing translation of potentially harmful transcripts. These transcripts remain functional however, and can be spliced where functional spliceosomes can be assembled.
5
Gupta, Meghana B. "Regulation of Dbl Family Guanine Nucleotide Exchange Factors". Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386175561.
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6
Fedler, Fritz. "Herstellung hochreflektierender AlGaN-AlN-DBR- und UV-VCSEL-Strukturen mittels plasmaunterstützter Molekularstrahlepitaxie". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969335695.
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JULIO, Ricardo Emerson. "DBML: Uma Biblioteca de Gerenciamento Dinâmico de Banda para Sistemas Multirrobôs Baseado em ROS". reponame:Repositório Institucional da UNIFEI, 2015. http://repositorio.unifei.edu.br:8080/xmlui/handle/123456789/114.
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A comunicação é um componente importante em sistemas multirrobôs; a performance do sistema pode ser seriamente afetada quando o número de robôs do sistema ou o número de canais de comunicação aumenta. A Biblioteca de Gerenciamento Dinâmico de Banda (DBML - Dynamic Bandwidth Management Library) foi projetada de forma a maximizar a utilização da banda em sistemas multirrobôs. O sistema desenvolvido prioriza os canais de comunicação de acordo com eventos que ocorrem no ambiente oferecendo maior largura de banda para os canais de comunicação mais prioritários. A biblioteca foi desenvolvida utilizando o ROS (Robot Operating System) de forma a separar as funcionalidades em módulos independentes que possam ser reutilizados e melhorados em trabalhos futuros. Este trabalho apresenta a biblioteca desenvolvida utilizando um problema de otimização linear e um exemplo do uso da biblioteca em uma aplicação de teleoperação onde diversas simulações foram feitas. Os resultados mostraram que o DBML atribui uma maior frequência de envio de informações para os canais de comunicação mais prioritários, permitindo assim, uma maior eficiência na execução das tarefas.
8
Rupp, Stephanie. "Modellgeleitete Diagnostik bei kindlichen lexikalischen Störungen [ausgezeichnet mit dem dbl-Forschungspreis]". Idstein Schulz-Kirchner, 2005. http://d-nb.info/988054396/04.
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9
Pozzi, Francesca. "InAlGaAs-InP laterally coupled DBR and DFB lasers for microwave generation". Thesis, University of Glasgow, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443408.
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Smilyanets, Sergey [Verfasser]. "Spieltheoretische Analyse eines Kampfes auf dem Ratingmarkt : Der Fall: DBRS gegen etablierte Ratingagenturen / Sergey Smilyanets". Aachen : Shaker, 2010. http://d-nb.info/1098042522/34.
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de, Moraes Rêgo Guedes Gabriela. "Efeitos da desnutrição protéica crônica sobre o córtex cerebral e evolução ponderal de ratos adultos". Universidade Federal de Pernambuco, 2009. https://repositorio.ufpe.br/handle/123456789/8583.
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Previous issue date: 2009Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Influências genéticas e ambientais atuam sobre o Sistema Nervoso Central (SNC) durante o processo de desenvolvimento. Uma nutrição adequada é essencial para a formação do SNC, organização funcional e para desenvolvimento do organismo. Estudos utilizando dietas semi-sintéticas foram desenvolvidos para reproduzir em animais de laboratório características clínicas, bioquímicas e patológicas, observadas em humanos desnutridos. A dieta básica regional (DBR) foi proposta para estudar a desnutrição característica dos habitantes de baixa renda da zona da mata de Pernambuco. O presente estudo avaliou o perfil morfológico (densidade e número de células neuronais) do córtex visual de ratos Wistar submetidos a dois tratamentos nutricionais: dieta padrão de biotério (Labina®, 23% de proteína) e dieta hipoprotéica (DBR, 8% de proteína), originando 6 grupos experimentais: N5, N7 e N9 - animais nutridos com Labina® durante 5º., 7º. e 9º. meses respectivamente, e D5, D7 e D9 - animais desnutridos por DBR durante os mesmos períodos. Após o tratamento nutricional, os animais foram sacrificados e os cérebros retirados, processados histologicamente e avaliados através de estudos morfométricos. Observou-se que a desnutrição induzida por DBR provocou uma redução significativa na massa corporal dos animais de todos os grupos. A redução foi decrescente ao longo da idade, pois aos 5 meses os animais DBR pesavam, em média, apenas 27,7% do peso total do animal normonutrido, aos 7 meses, 29,1% e por fim aos 9 meses os animais DBR pesavam cerca de 32% do peso dos normonutridos. A comparação feita entre os grupos mostrou que o peso cerebral também foi visivelmente reduzido nos animais desnutridos. A maior redução no peso cerebral ocorreu no grupo D9 onde a média do peso dos cérebros desse grupo correspondia a 81,55% do peso cerebral do grupo N9. Não houve diferença significativa em relação ao número de neurônios por campo e nem em relação à média da área do soma dos neurônios. Tais achados indicaram que a desnutrição induzida pela DBR no pós-desmame embora não cause alterações na citomorfologia do córtex cerebral tem repercussões sobre a evolução ponderal e encefálica
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SANTOS, Ângela Amâncio dos. "Nutrição e sistemas serotoninérgico e nitrérgico: estudo morfo-funcional em ratos jovens e adultos". Universidade Federal de Pernambuco, 2006. https://repositorio.ufpe.br/handle/123456789/8830.
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Previous issue date: 2006Estudo Eletrofisiológico: Ratos Wistar foram injetados durante o período de lactação com fluoxetina, um inibidor seletivo da recaptação de serotonina (5, 10, 20, ou 40 mg/kg/d por via subcutânea) e o fenômeno da depressão alastrante da atividade elétrica cerebral (DA) foi registrado na superfície cortical desses animais imediatamente após o desmame (25-30 dias de vida). Em um grupo adicional (10 mg/kg) a DA foi registrada aos 60-70 dias. Quando comparada às duas condições controle (injeção com solução salina ou sem injeção - ingênuos ), a fluoxetina reduziu (P<0,05) a velocidade da DA nos ratos jovens de forma dose-dependente em 4%, 6%, 16% e 15%, respectivamente, e nos adultos em 13%. Em um outro experimento com ratos adultos, a aplicação tópica cortical de fluoxetina (5 e 10 mg/ml) sobre a dura-máter intacta, durante 10 min, reduziu a velocidade da DA de modo diretamente proporcional à concentração aplicada (reduções máximas de 7,6% e 43,3%; P<0,05). A propagação da DA foi bloqueada em 4 dos 14 ratos tratados topicamente com a concentração mais alta de fluoxetina (10 mg/ml). Este efeito tópico da fluoxetina foi revertido após lavagem, da região tratada, com solução salina. Em ratos precocemente desnutridos, a fluoxetina aplicada durante o período de aleitamento (10 mg/kg/d, s.c.) e topicamente (10 mg/ml) também reduziu (P<0.05) as velocidades da DA em 18 e 22% para o tratamento sistêmico (nos animais jovens e adultos, respectivamente) e em 22,4% para o tratamento tópico. Estudo Morfológico: Em ratos Wistar tratados precocemente com fluoxetina (10 mg/kg/d, s.c.) não houve modificações apreciáveis no número, nem na área do corpo celular de neurônios nicotinamida adenina dinucleotídeo fosfato-diaforase (NADPH-d) positivos, independentemente do estado nutricional. Neurogênese Hipocampal: A fluoxetina não alterou o número de células hipocampais positivas à bromodeoxiuridina (marcador de proliferação celular) em ratos Sprague- Dawley jovens ou adultos, submetidos ou não a uma condição de estresse. Conclusões: 1) A presente ação da fluoxetina suporta a hipótese de uma influência serotoninérgica antagônica sobre a DA; 2) A desnutrição precoce não impede os efeitos da fluoxetina; 3) A neurogênese hipocampal, bem como as células NADPH-d-positivas (que são produtoras de óxido nítrico) parecem ser resistentes ao tratamento precoce com esse inibidor seletivo da recaptação de serotonina
13
Chiccone, Christopher Louis. "Automated SG-DBR Tunable Laser Calibration Optimized for Optical Coherence Tomography Applications". DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/519.
Testo completoAbstract (sommario):
SG-DBR lasers look to solve many problems associated with present OCT sources by being cost effective, smaller in size, more robust, and by operating at faster repetition rates. Swept Source Optical Coherence Tomography (SS-OCT) requires a tunable laser source that exhibits linear frequency sweeps, large frequency spans, and high repetition rates. This work accomplishes this by using four synchronized waveforms sent to the input of a Sampled Grating-Distributed Bragg Reflector (SG-DBR) laser. Three mirrors control the wavelength, while an internal semiconductor optical amplifier controls the laser output power. In dealing with this complicated tuning mechanism, a manual sweep calibration is too time-consuming. This thesis demonstrates an efficient method for automating the calibration of tunable SG-DBR lasers by implementing a gain medium voltage sensing algorithm, as opposed to the previous inefficient manual efforts.
Experimental OCT tests are also performed by utilizing a Mach-Zehnder interferometer as a device under test to verify the accuracy of the laser calibration methodology. The OCT response to a single reflection event is measured over a range of repetition rates. A method to reduce these spurious display responses caused by wavelength stitching imperfections is implemented through a self-generating optical clock.
14
Li, Xin. "Lasers à cavité vertical émettant par la surface dans l’ultraviolet profond à base des matériaux BAlGaN". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0243/document.
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Le contexte de cette thèse se situe dans les nombreuses applications de sources UV tels que la stérilisation et la purification. Comparés aux sources conventionnelles, les dispositifs à base de semiconducteur présentent la fiabilité, l'efficacité élevée, et les effets minimaux sur l'environnement. Sur l'aspect des matériaux, III-Nitrures (BAlGaInN) sont les candidats prometteurs car ils sont stables chimiquement et physiquement, et ils présentent les bandes interdites couvrant le spectre visible à l'UV profond. Sur l'aspect des structures, le laser à cavité vertical émettant par la surface (VCSEL) est l'une des configurations les plus attrayantes, et il offre des avantages tels que le seuil bas, le haut rendement, la possibilité d'intégration des réseaux 2D et les tests au niveau de la plaquette. Néanmoins, il n'existe aucun VCSEL fonctionnant en dessous de 300 nm. Des défis importants concernent l'efficacité de MQWs et la réflectivité de réflecteur de Bragg distribué (DBR), qui sont limitées par la qualité des matériaux, les propriétés optiques des MQWs, le contraste faible d'indice de réfraction pour les couches dans les DBRs à des longueurs d'onde courtes, etc. L'objectif de cette thèse est de répondre aux défis relevés auparavant en étudiant la croissance de BAlGaN par épitaxie en phase vapeur aux organométalliques (MOVPE), en développant les MQWs d'AlGaN avec l'augmentation des émissions par la surface, et en explorant les DBRs en BAlN/AlGaN, en vue du développement de VCSEL à pompage optique fonctionnant dans DUVThe context of this thesis falls in the wide applications of UV light sources such as sterilization and purification. Compared to the conventional UV sources (excimer lasers, Nd: YAG lasers or mercury lamps), the semiconductor devices have advantages in reliability, compactness, high efficiency and minimum environmental effects. On the material aspect, III-nitrides (BAlGaInN) are promising candidates since they are chemically and physically stable with direct bandgaps covering from visible to DUV spectrum. On the structure aspect, vertical-cavity surface-emitting laser (VCSEL) is one of the most attractive configurations considering its low threshold, high efficiency, and the possibility for the integration of 2D arrays and the wafer-level tests. It constitutes a multiple-quantum-well (MQW) active region sandwiched by a top and a bottom distributed Bragg reflector (DBR). However, no VCSELs can operate below 300 nm until now. The major challenges lie in the two main blocks: the emission efficiency of MQWs and the reflectivity of DBRs, which are limited by the quality of the substrates and epitaxial layers, optical-polarization properties of the MQW emission, small refractive index contrast of the layers used for DBRs at short wavelengths, etc. The objective of this thesis is to address this need by studying metal-organic vapor-phase epitaxy (MOVPE) growth of BAlGaN materials, developing AlGaN MQWs with enhanced surface emission and exploring BAlN/AlGaN DBRs, for the future development of optically-pumped VCSELs operating below 300 nm
15
Abid, Mohamed. "Design and epitaxial growth of vertical cavity surface-emitting lasers (VCSEL) emitting at ultraviolet wavelength". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47682.
Testo completoAbstract (sommario):
One of the key advances in photonic technology in recent decades was the development of a new type of diode lasers emitting in the visible and infrared region. These vertical cavity surface-emitting lasers (VCSELs) emerged from a laboratory curiosity in 1977 [13] to an object of industrial mass production [14] and are currently used in many applications. The applications include communication, printing, and absorption spectroscopy [15]. Their rise in credibility has largely been motivated by the rapid evolution of their performance, the more sweeping recognition of their compatibility with low-cost wafer-scale fabrication, and their possible formation into specific arrays with no change in the fabrication procedure.
Various applications such as advanced chemical sensors and high-density optical storage require coherent and small-size ultraviolet-emitting devices (below 400nm). Therefore, to extend the VCSEL emission to the ultraviolet (UV) region, intensive efforts have been made in the VCSEL technology. However, the achievement of such UV VCSEL is very challenging because of the various limitations and issues. The issues noticeably include the carrier injection, optical confinement, and highly reflective distributed Bragg reflectors (DBR) structures with a broad bandwidth operating in the UV region [16]. In this context, motivated by the reported large refractive index induced by boron incorporation [7], we propose to introduce the boron-based material systems (BAlGaN) as an innovative solution to address some of the encountered difficulties.
The objective of the proposed research is to investigate and optimize new wide-bandgap BAlGaN material systems and illustrate their incorporation into the building blocks of vertical cavity surface-emitting laser structures for operation in the UV spectral range (<400nm).
Toward this goal, we have focused our research activities in three main directions. The first direction is devoted to the simulation of DBRs reflectivity by taking into consideration the experimental refractive indexes. Once the materials needed in the different components of the VCSEL are well defined, the second direction lies in the achievement of growth conditions optimization and characterization of the new wide-bandgap BAlGaN material systems. The study has led to the structural and morphological quality improvement of (B,Al,Ga)N materials. Unique optical properties of the BGaN and BAlN materials were also demonstrated. Upon demonstrating the materials' promising optical characteristics, the final direction consists of the epitaxial growth and characterization of the highly reflective DBRs and active region of the UV VCSEL structure.
16
Riehn, Eric J. [Verfasser]. "Photokathoden mit internem DBR-Reflektor als Quellen hochintensiver spinpolarisierter Elektronenstrahlen / Eric J. Riehn". Mainz : Universitätsbibliothek Mainz, 2011. http://d-nb.info/1031800050/34.
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Gilbert, David Wilkey. "Point-Spread Function Assessment of SG-DBR Based Swept Source for OCT Imaging". DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/733.
Testo completoAbstract (sommario):
Swept Source Optical Coherence Tomography (SS-OCT) is a medical imaging technique that requires high repetition rate, widely-tunable coherent laser sources. Sampled grating distributed Bragg reflector (SG-DBR) lasers are proven in telecom applications and are expected to fulfill the requirements for SS-OCT at a significantly lower cost than alternative solutions.
Constructed entirely on a semiconductor substrate, SG-DBR lasers require four synchronized waveforms to modulate the output wavelength and intensity. Because of this unique tuning mechanism, there are a number of systematic and noise sources that can affect the quality of the OCT point-spread function (PSF). Based on these noise sources, software is developed to simulate the waveforms in an SS-OCT system and determine the factors that limit width of the PSF central peak and the broadband skirts. Design curves are then created to specify the requirements to obtain a given performance.
Next, experimental tests are performed on a JDS Uniphase C-band SG-DBR laser to assess its performance limitations. Finally, by comparing theory and experiment, recommendations are made on acceptable systematic and random noise errors induced in the PSF.
18
Svensson, Alexandra. "En studie över förekomsten av genuttryck för enzym i biosyntesen av malarialäkemedlet artemisinin hos Artemisia vulgaris och Artemisia absinthium". Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35332.
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Malaria är en farlig tropiksjukdom orsakad av parasiten Plasmodium som vållar många dödsfall varje år. Sedan några år tillbaka rekommenderar Världshälsoorganisationen (WHO) användandet av artemisinin och dess derivat för behandlandet av malaria. Artemisinin syntetiseras normalt i växten Artemisia annua i lågt utbyte. På grund av det låga utbytet är läkemedlet väldigt dyrt. Då parasiten blivit resistent mot de flesta malarialäkemedel är artemisinin ett viktigt preparat i kampen mot malaria. Forskning pågår för att hitta nya eller effektivare metoder för framställning av substansen då en oro finns att produktionen från A. annua inte kommer kunna möta kraven från läkemedelsindustrin. En av teorierna är ifall andra växter inom Artemisia-släktet kan syntetisera artemisinin då flera växter uppvisat helande effekter vid andra sjukdomar. I denna studie undersöktes det ifall växterna A. vulgaris och A. absinthium från Artemisia-släktet skulle kunna syntetisera artemisinin. Med hjälp av molekylärbiologiska tekniker isolerades genetiskt material ifrån växterna. Materialet granskades efter ribonukleinsyra (RNA)- och deoxiribonukleinsyra (DNA) -sekvenser för funktionella enzym som katalyserar reaktioner i artemisinins biosyntes. Ifall generna uttrycks för dessa enzym kan eventuellt artemisinin bildas. Växterna hämtades från Revsudden, Sverige och genetiskt material isolerades. Förekomsten av genuttryck för fem viktiga enzym i artemisinins biosyntes undersöktes med Polymerase Chain Reaction (PCR). Resultatet blev att växterna hade genuttryck för två respektive tre av de fem enzymen. Detta pekar mot att varken A. vulgaris eller A. absinthium kan syntetisera artemisinin då de saknade några viktiga nyckelenzym i syntesen. Trots att en tidigare studie indikerar närvaro av artemisinin i dessa växter kan slutsatsen dras att A. vulgaris och A. absinthium inte kan bilda artemisinin.Malaria is a tropical disease that accounts for the death of many people annually and is caused by a parasite called Plasmodium. The World Health Organization (WHO) recommends artemisinin and its derivates for malaria treatment. Artemisinin is synthesized generally in Artemisia annua in small amounts. The artemisinin-treatment is very expensive due to the small amounts produced in the plant. Since the parasite has developed resistance towards many antimalarial drugs, artemisinin is an important drug against malaria. Research to find alternative methods for artemisinin-production has begun because there is a great concern that artemisinin-production at current rate will not meet the demand from the pharmaceutical industry. Some speculate if artemisinin can be synthesized in other plants from the Artemisia-genus since many plants have shown healing properties towards other diseases. In this study, we investigated if A. vulgaris and A. absinthium could produce artemisinin. Using molecular biology techniques, genetic material was isolated from the plants. Ribonucleotide (RNA)- and deoxyribonucleotide (DNA)- sequences which encode important enzymes in the artemisinin biosynthesis were examined. In case all the genes were expressed, artemisinin may be synthesized. The plants were picked on Revsudden, Sweden and genetic material was isolated. The presence of gene expression of five important enzymes in the artemisinin biosynthesis was investigated by Polymerase Chain Reaction (PCR). The results showed that the plants had gene expression of two respectively three of the five enzymes. Due to the fact that the plants need all five enzymes to synthesize artemisinin, even though a recent study has shown presence of artemisinin in these plants, this study concludes that artemisinin cannot be synthesized in A. vulgaris and A. absinthium.
19
Bashir, Babar. "Designing of High Reflectance Distributed Bragg reflectors (DBRs),mirrors using AlGaInN material system in the UV wavelength range". Thesis, University of Gävle, Ämnesavdelningen för elektronik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-5423.
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Friebel, Andrea. "Substratspezifität der nicht-dbl-homologen G-Nukleotid-Austauschfaktoren SopE und SopE2 aus Salmonella typhimurium". Diss., lmu, 2002. http://nbn-resolving.de/urn:nbn:de:bvb:19-1066.
Testo completo
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Cesar, Julijan [Verfasser], Thomas [Akademischer Betreuer] Kusserow e Stefan [Akademischer Betreuer] Sinzinger. "SiOx-SiCz MEMS-DBR-Based Tunable Optical Devices / Julijan Cesar ; Thomas Kusserow, Stefan Sinzinger". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1219656070/34.
Testo completo
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Cesar, Julijan Verfasser], Thomas [Akademischer Betreuer] [Kusserow e Stefan [Akademischer Betreuer] Sinzinger. "SiOx-SiCz MEMS-DBR-Based Tunable Optical Devices / Julijan Cesar ; Thomas Kusserow, Stefan Sinzinger". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-135633.
Testo completo
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Durel, Jocelyn. "Intégration d’un laser hybride DBR III-V/Si en face arrière d’une puce photonique". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT026/document.
Testo completoAbstract (sommario):
Ces dernières années, la photonique sur silicium est apparue comme une solution prometteuse pour la fabrication en grande série d'émetteurs-récepteurs optiques répondant aux besoins des centres de données en termes d'augmentation du débit et de coûts réduits. Plusieurs plateformes de photonique sur silicium ont été démontrées en utilisant la technologie Si standard. Bien que ces plateformes diffèrent à bien des égards, elles manquent toutes d'une source de lumière intégrée monolithiquement. Pour résoudre ce problème, l'approche la plus couramment proposée consiste à coller un empilement InP sur une plaque SOI afin de fabriquer un laser hybride III-V/Si. Cependant, aucune des démonstrations n'a été réalisée avec un empilement d’interconnexions métalliques BEOL (Back-End Of Line) standard, empêchant ainsi une intégration électronique-photonique appropriée. Pour résoudre le problème topographique posé par cet ajout de couches, un nouveau schéma d'intégration, appelé intégration Back-Side, a été développé et est présenté dans ce document.Tout d'abord, le contexte de cette étude, un état de l’art ainsi que la présentation du Back-Side est abordé. La nouveauté apportée par cette intégration, à savoir le collage du III-V sur la face arrière du SOI après la structuration de celui-ci, y est alors détaillé.Le bon fonctionnement d’un élément essentiel à la puce photonique, le réseau de couplage, est ensuite abordé à travers des simulations, sa fabrication et des caractérisations optiques. Nous avons prouvé que, sous certaines conditions, ce dispositif possède les mêmes performances mesurées en Back-Side qu’en Front-Side.Le principe de fonctionnement d’une cavité oscillante puis les différents modules composants le laser hybride sont détaillés. Le laser étudié est une cavité hybride DBR (Distributed Bragg Reflector) III-V/Si. Afin d'augmenter le confinement du mode dans le MQWs (Multi Quantum Wells) et donc d'assurer un gain optique élevé, le mode optique est progressivement transféré entre le guide III-V et le guide silicium du laser hybride par des épanouisseurs adiabatiques, structurés dans le SOI de part et d’autre de la zone de gain, pour être enfin réfléchi par les miroirs DBR dans le silicium.Enfin, son processus de fabrication est explicité avant que ses caractérisations opto-électroniques ne soient finalement présentées. Les lasers à pompage électrique ont été testés dans des conditions de courant continu et la lumière générée a été collectée à travers un réseau de couplage par une fibre optique externe multimode. Les pertes de couplage ont été mesurées supérieures à 10 dB. La puissance de sortie est de 1,15 mW à un courant d'injection de 200 mA. Le seuil laser est de 45 mA, ce qui correspond à une densité de courant de 1,5 kA / cm2 et la résistance série des contacts laser est d'environ 9 Ω. La tension de seuil est de 1,45 V. Les spectres lasers reflètent un fonctionnement mono-fréquence, pour différents courants d'injection, avec une longueur d'onde centrale correspondant à la longueur d’onde de Bragg des miroirs. Un SMSR (Side Mode Suppression Ratio) de plus de 35 dB a été mesuré, ce qui prouve la bonne pureté spectrale de ce laser. Un décalage de la longueur d'onde de 4 nm a été observé en injectant un courant de 20 mA dans des chaufferettes métalliques au-dessus des DBRs.L'intégration monolithique d'un laser DBR hybride en face arrière d'une plaque SOI, entièrement compatible CMOS, a été démontrée pour la première fois, la mise en place d'interconnexions électriques compatibles CMOS et de sources optiques sur une même puce a pu être réalisée. Ce dispositif ouvre la voie à un émetteur-récepteur optique entièrement intégré sur une plateforme SiRecently, Silicon Photonics has emerged as a solution for the mass manufacturing of optical transceivers addressing datacenter’s needs in terms of increasing data-rate and reduced cost. Several Silicon-Photonics platforms have been demonstrated using standard Si technology. While these platforms differ in many regards, they all lack a solution for a monolithically integrated light source. To solve this problem, the most commonly proposed approach consists in bonding an InP-stack onto a Si-wafer in order to fabricate a Hybrid III-V/Si laser. However, none of those demonstrations have been made with a standard CMOS-BEOL, preventing a proper electronic-photonic integration. To solve the topographical problem induced by the additional layers, a new integration scheme, called Back-Side, has been developed and is presented in this document.First, the context of this study, a state of the art as well as the presentation of the Back-Side is discussed. The innovation brought by this integration, namely the bonding of the III-V on the back side of the SOI after the structuring of the latter, is then detailed.The correct behavior of a key element to the photonic chip, the grating coupler, is then treated through simulations, fabrication and optical characterizations. We have proved that, under specific conditions, this device has the same measured performances in Back-Side and in Front-Side.The principle of an optical oscillator and then the various modules composing the hybrid laser are then detailed. The implemented laser is based on a hybrid DBR (Distributed Bragg Reflector) III-V/Si cavity. In order to increase the mode confinement in the MQWS (Multi Quantum Wells) and hence ensure a high optical gain, the optical mode is gradually transferred between the III-V waveguide and the silicon waveguide of the hybrid laser by adiabatic tapers, patterned on both sides of the gain zone, to finally be reflected by the mirrors DBR in the silicon.Finally, its manufacturing process is explained before its opto-electronic characterizations are presented. The electrically pumped lasers have been tested under continuous-wave current conditions and the generated light has been collected through the grating coupler to a multi-mode fiber. The fiber coupling losses has been measured to be higher than 10 dB. The output power is up to 1.15 mW at an injection current of 200 mA. The lasing threshold is 45 mA which corresponds to a current density of 1.5 kA/cm2 and the series resistance of the laser contacts is approximately 9 . The threshold voltage is 1.45 V.The laser spectra reflect its single-wavelength laser operation, for different injection currents, with a central wavelength corresponding to the Bragg wavelength of the mirrors. A Side Mode Suppression Ratio (SMSR) of more than 35 dB has been measured. A 4 nm wavelength shift has been observed when injecting 20 mA into both metallic heaters above DBRs.The monolithic integration of a fully CMOS compatible hybrid DBR laser on the backside of a SOI wafer being demonstrated for the first time, implementing CMOS compatible electric interconnects and optical sources on a same chip has could be achieved. This device opens the route to a fully integrated optical transceiver on a Si platform
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Bernacil, Michael A. "Microwave Signal Generation Using Self-Heterodyning of a Fast Wavelength Switching SG-DBR Laser". DigitalCommons@CalPoly, 2008. https://digitalcommons.calpoly.edu/theses/19.
Testo completoAbstract (sommario):
Microwave signal generation is demonstrated using a single-chip fast wavelength-tunable SG-DBR laser. Microwave signals are established by a delayed self-heterodyne technique. The optical frequency of the laser is square-wave modulated between two closely spaced wavelengths. These two wavelengths are made time coincident using a fiber based Mach-Zehnder interferometer. From the interferometer, the difference frequency is detected and amplified. The optical difference frequency takes on the form of a microwave signal that can be seen on an electrical spectrum analyzer. The hardware structure of the high-speed wavelength switching SG-DBR package is shown. The wavelength switching architecture and temperature robustness of the laser will also be presented.
Microwave signals up to 17 GHz have been generated by frequency modulating the phase section of the laser. Measured from the microwave signal spectral width, laser linewidth values as narrow as 10 MHz have been achieved for low back mirror current inputs. Linewidth results with respect to device DC bias conditions are also presented. Time resolved frequency step measurements have shown inherent thermal transients of approximately 200 ns upon wavelength switching. From the square wave switching profile, switching times of approximately 24 ns were achieved.
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Chhatriwala, Mariya Khuzem Sondek John E. "Defining diverse mechanisms that regulate the activity of Dbl-family guanine nucleotide exchange factors". Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1494.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Sep. 16, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Pharmacology." Discipline: Pharmacology; Department/School: Medicine.
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Ruppik, Stefan [Verfasser]. "Zeitvariante optisch induzierte DBR-Filter auf halbleiterbasierten Koplanarleitungen für den Mikro- und Millimeterwellenbereich / Stefan Ruppik". Hamburg : Helmut-Schmidt-Universität, Bibliothek, 2012. http://d-nb.info/1018559930/34.
Testo completo
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Durand, Fábio Renan. "Projeto e modelagem de um filtro para retirada de comprimentos de onda utilizando duplo refletor de Bragg e guias ARROW em fibras tipo-D para aplicações em WDM". Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-08032016-115713/.
Testo completoAbstract (sommario):
A sociedade atual está vivendo uma revolução baseada na informação. A recente explosão da popularidade da internet e desregulamentação dos setores públicos de telefonia em muitos países foram os principais responsáveis pelo aumento da demanda por largura de banda. Adicionalmente, houve um aumento no volume de tráfego em função do oferecimento de serviços multimídia de banda larga. Este cresimento rápido e global por demanda de largura de banda está acelerando o desenvolvimento e a implantação de redes de comunicações ópticas empregnando sistemas multiplexados em comprimento de onda (WDM). O emprego de fibras na transmissão de informações em alta velocidade a grandes distâncias já está consolidado, e sua utilização em redes metropolitanas MAN (Metropolitan Area Network) e redes de acesso está aumentando. Verifica-se que a tendência de evolução das redes ópticas é a aproximação das fibras até o usuário final. A forma mais viável economicamente de aproximar o usuário dos benefícios das redes ópticas com grande capacidade é o emprego de redes ópticas passivas PON (Passive Optical Network) empregando o sistema WDM. Este tipo de rede apresenta a flexibilidade de suportar tanto broadcast, onde o mesmo sinal é distribuído a todos os usuários, como serviços ponto-a-ponto. Um dos requisitos mais importantes para o aumento da capacidade destes sistemas ópticos é o aumento do número de canais (comprimentos de onda). Para viabilizar este aumento do número de canais é necessária a utilização de dispositivos com alta seletividade em comprimento de onda proposto neste trabalho. Este filtro é composto pela combinação de três estruturas distintas formando um único dispositivo: fibra tipo D, duplo refletor de Bragg (DBR), e guia multicamada em configuração ARROW ( Antiresonant Reflecting Optical Waveguide). O DBR é previamente definido na fibra tipo D e esta é então colada sobre a estrutura multicamada. ) A estrutura multicamada, por sua vez, possui a configuração ARROW em virtude de suas características de seletividade em comprimento de onda. A utilização de um fibra tipo D no dispositivo proposto permite que as perdas de inserção deste dispositivo no enlace óptico sejam drasticamente reduzidas. Este trabalho realiza um projeto criterioso de um filtro em questão, buscando valores ótimos para cada um dos parâmetros que compõem este dispositivo, tais como: espessuras de camadas, índices de refração, perda de inserção, isolação entre canais, etc. Os resultados obtidos com as simulações são discutidos e uma configuração ótima para o dispositivo é proposta.The progress in lightwave propagation based on optical fibers has provided our society with an unprecedented communication capability. The deregulation of public telephone companies together with the increasingly popularity of the internet can be pointed out as the major contributors for this huge bandwidth demand we experience today. Additionally, there was a corresponding growth in traffic volume due to wideband multimedia services. As a consequence of this fast growing demand for bandwidth in a global scale, telecom companies have accelerated the development and implementation of optical communication networks based on wavelength division multiplexing (WDM) technology. The tendency in terms of network evolution is to approximate the optical fibers as close as possible to the end user. The most economically viable way of doing so is by way of the so called Passive Optical Networks (PON) based on WDM systems. This type of network is flexible enough to support broadcast, where the same signal is distributed to all users, and point-to-point services. If more capacity is required for these systems, this can be achieved just by adding new channels (wavelengths) to it. Another important issue regarding WDM systems consists in the extraction of channels from the optical network, which can be achieved by using highly selective dropping filters such as the one proposed in this work. This filter is defined by the combination of three distinct structures defining one single device: a d-type fiber, a double Bragg reflector (DBR), and a multilayer ARROW type waveguide (Antiresonant Reflecting Optical Waveguide). The DBR is defined beforehand on the d-fiber, and then the d-fiber is literally glued on top of the multilayer waveguide. This multilayer waveguide is fabricated directly atop of a p-i-n photodetector in such a way that the three structures (d-fiber, multilayer waveguide and photodetector) now form a rigid structure. The ARROW type configuration for the multilayer waveguide and the DBR structure are chosen by virtue of their wavelength selectivity characteristics, helping to improve the device performance. The d-fiber structure, by its tum, has the great advantage of reducing drastically the insertion loss when compared to rectangular waveguide filters. In the analysis provided in this work parameters such as layer thicknesses, refractive indices, insertion loss, channel isolation, etc, and their influence on the device performance, are extensively investigated for optimization purposes. The simulated results are discussed thoroughly and an optimal structure configuration is proposed.
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de, Assis Marques Santos Francisco. "Efeito da desnutrição pós-natal com DBR (Dieta Básica Regional) sobre a morfometria testicular e o processo espermatogênico de ratos adultos". Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/8319.
Testo completoAbstract (sommario):
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Previous issue date: 2008Objetivamos investigar o efeito da desnutrição materna durante a lactação, com a Dieta Básica Regional (DBR), no testículo de ratos, através de análises quantitativa e qualitativas. Ratas Wistar acasaladas aos 3 meses de idade receberam ração normoprotéica até o nascimento dos seus filhotes. Os filhotes foram divididos em dois grupos: controle C (n=6), com água e dieta normoprotéica; e desnutrido D (n=6), com água e dieta multicarencial (DBR); dada às mães, lactantes. Após o desmame, os grupos foram mantidos com água e dieta padrão do biotério (Labina-Purina), ad libitum até a eutanásia aos 3 meses de vida quando foram pesados, anestesiados, perfundidos com paraformaldeído a 4% em tampão fosfato (0,05M - pH 7,4) e orquiectomizados. O índice gonadossomático (IGS) foi estabelecido a partir da razão entre os pesos testiculares e corporal, obtidos no dia da eutanásia. Os testículos foram incluídos em parafina, processados histologicamente e corados com hematoxilina e eosina, depois analisados em microscópio de campo claro. Os pesos corporal (PC) e testicular (PT) do grupo desnutrido (324±6g; 1,67±0,05g) não diferiram dos pesos corporal e testicular do grupo controle (303±10g; 1,67±0,03g). Já o índice gonadossomático (IGS) do grupo desnutrido (1,11%) foi significativamente maior (p=0,021) do que o IGS do grupo controle (1,04%). O diâmetro tubular (DT) do grupo desnutrido (300±3μm) foi semelhante ao grupo controle (295±2μm), da mesma forma o comprimento do túbulo seminífero por testículo (CTS) do grupo desnutrido (16,9±0,7m) foi próximo do CTS do grupo controle (18±1,7m), ou seja, não houve diferença estatística significativa (p>0,05). Entretanto a altura do epitélio seminífero (AES) do grupo desnutrido (74±2μm) foi estatisticamente menor (p<0,05) do que a AES do grupo controle (82±3μm). A proporção de túbulos seminíferos foi menor (p<0,05) no D(84,0%) em relação ao C(81,7%). Houve redução de 48,8% no número de células de Sertoli por testículo do D (2,1±0,3 x107) em relação ao C(4,1±0,8 x107) (p<0,05). Os resultados sugerem que a desnutrição pós-natal com DBR em ratos adultos jovens, promoveu modificações significativas nos testículos, com ênfase na programação do número de células de Sertoli, no animal adulto, o que pode levar a alteração no processo espermatogênico e na produção espermática
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Bernacil, Michael A. Derickson Dennis. "Microwave signal generation using self-heterodyning of a fast wavelength switching SG-DBR laser : a thesis /". [San Luis Obispo, Calif. : California Polytechnic State University], 2008. http://digitalcommons.calpoly.edu/theses/19/.
Testo completoAbstract (sommario):
Thesis (M.S.)--California Polytechnic State University, 2008.Major professor: Dennis Derickson, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "May 2008." Includes bibliographical references (leaves 147-149). Also available on microfiche (3 sheets).
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Govoni, Humberto. "Análise de estratégias de melhorias de recursos produtivos em ambientes MTS gerenciados pelo método S-DBR /". Bauru, 2018. http://hdl.handle.net/11449/180542.
Testo completoAbstract (sommario):
Orientador: Fernando Bernardi de SouzaBanca: Silvio Roberto Ignacio Pires
Banca: Jose de Souza Rodrigues
Resumo: A análise do comportamento do fluxo das ordens de produção e dos recursos que compõem um sistema produtivo oferece um indicativo de onde se deve atuar para melhorar este sistema. A Teoria das Restrições (Theory of Constraints - TOC) indica três métodos de focalização de melhorias de recursos produtivos que impactam globalmente o sistema. Este trabalho busca avaliar o desempenho de cinco métodos de melhoria, incluindo os indicados pela TOC, em um ambiente de produção para estoque (make-to-stock - MTS) utilizando-se de simulação computacional. Para isto, estas abordagens são simuladas em seis configurações de linha de produção e o desempenho é medido em termos de Tempo de Ciclo (Cycle Time - CT) e Taxa de Preenchimento de Pedidos (Fill Rate - FR). Os resultados indicam que, em sistemas balanceados, a melhor abordagem de melhoria a ser utilizada é a que atua em todos os recursos simultaneamente. Em ambientes desbalanceados, por outro lado, é necessário utilizar um método que foca melhorias em um único recurso, como o método de nível de ocupação, estoque em processo ou Buffer Management. Neste caso, a focalização pelo nível de ocupação da máquina trouxe mais benefícios ao sistema.
Abstract: A behavioral analysis of the flow of production orders and resources that form a production system provides an indication of where to improve this system. The Theory of Constraints (TOC) suggests three approaches for identifying and improving resource constraints aiming to entirely affect the system: based on the largest queue of work-in-progress, the highest utilization level, and using the buffer management method. This study aims to assess the performance of these approaches comparing them with each other and with two others: dispersed improvements in all the resources and random improvements. Data was taken and analyzed from a simulated make-to-stock (MTS) environment, managed using the Simplified Drum Buffer Rope (S-DBR) method. For this, each improvement approach is simulated in six production line configurations and performance is measured in terms of Cycle Time (CT) and Fill Rate (FR). The results indicate that, in balanced systems, scattered improvements in all resources allowed better results than all three approaches recommended by TOC. In unbalanced environments, on the other hand, the focus on occupancy level exceeded all the other four approaches assessed.
Mestre
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Bahari, Aireen Aina Binti. "The implementation of dialogue-based pedagogy to improve written argumentation amongst secondary school students in Malaysia". Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34992.
Testo completoAbstract (sommario):
The purpose of this study is to find solutions on how to improve secondary school students’ persuasive argumentative English essay writing. The participants of this study are groups of ESL students aged 13 and 17 who live and study in a sub-urban area in Malaysia. All students and teachers converse amongst themselves using the Malay language on a daily basis while English language is merely used during classroom interaction time. Not only do they have very little opportunity to communicate using English language in their daily lives and for academic purposes, they also have limited opportunity to learn how to argue persuasively in their English classroom. Thus, they have difficulties in writing two-sided argumentative essays in English. The teaching-to-the-test culture has taken its toll on students’ writing performance when writing argumentative essays. In order to help students to score well in examination, teachers often overlook the need to teach critical thinking skills for the English subject. They focus solely on writing narrative essays as these essays require less critical thinking skill from the students. The Design-Based Research is employed to solve this problem of writing persuasive argumentative essays. Based on the pre-intervention essays written by the participants, it is believed that their difficulties are because of two major factors; insufficient English language skills and no exposure to persuasive argumentation skills. The initial design framework asserts that students should improve their persuasive argumentative essay writing if they are initially exposed to face-to-face group argumentation. However, the findings from the exploratory study revealed that face-to-face group argumentation is unmanageable in the context studied. Hence, an online learning intervention was considered to support secondary school students to improve their written argument. It was developed underpinned by design principles based on Exploratory Talk to achieve persuasive argumentation. The prototype online intervention was tested and developed through a series of iterations. Findings from Iteration 1 show that only a small number of students manage to write two-sided essays because most of them have an extreme attitude when writing about an issue and display a lack of positive transfer from group to individual argumentation. Prior to Iteration 2, the prototype intervention was adapted to tackle the extreme attitude and negative transfer issues by highlighting five elements: face-to-face classroom practice, focus more on three main ground rules, argument game, role of teachers during group argumentation and the use of argument map during the post-intervention essay writing. The findings demonstrate that all students in the second iteration wrote argumentative essays which are more persuasive. The final design framework developed in this study suggests a design framework that could be used by future researchers and ESL teachers at secondary school level who are interested in improving students’ persuasive argumentative essays.
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Tapanes, Marie A. "Revision And Validation Of A Culturally-Adapted Online Instructional Module Using Edmundson's CAP Model: A DBR Study". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3376.
Testo completoAbstract (sommario):
In the present study, the Cultural Adaptation Process Model was applied to an online module to include adaptations responsive to the online students' culturally-influenced learning styles and preferences. The purpose was to provide the online learners with a variety of course material presentations, where the e-learners had the opportunity to select their preferred structure for learning. The research methodology for the study is Design-Based Research (DBR), which has been identified by many prominent researchers in Instructional Technology as the most productive research approach for the field. DBR integrates different data types and data collection methods (quantitative, qualitative, and mixed) with experience in instructional development and the participants' collaboration. The study produced design principles that are expected to be useful for practitioners when adapting online courses to multicultural audiences. To provide thorough information to instructional designers, the research report includes a detailed description of each phase, an estimate of hours invested per development and testing stages, a list of outcomes found, and a set of recommendations for improving the cultural adaptation model applied. The study is expected to be valuable for educational institutions and corporations that offer online courses to multicultural groups of e-learners.
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Yoshizawa, Masato. "Dynamic and coordinated expression profiles of Dbl-family guanine nucleotide exchange factors in the developing mouse brain". Kyoto University, 2005. http://hdl.handle.net/2433/144747.
Testo completo
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Talkington, Desmond Charles. "Characterization and Modeling of an O-Band 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) Laser for Optical Coherence Tomography (OCT) Applications". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/983.
Testo completoAbstract (sommario):
In this project, the performance aspects of a new early generation 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) semiconductor laser are investigated. SG-DBR lasers are ideal for Source Swept Optical Coherence Tomography (SS-OCT), a Fourier-Domain based approach for OCT, necessitating a tunable wavelength source. Three internal sections control the frequency output for tuning, along with two amplifiers for amplitude control. These O-band SG-DBR devices are now being produced in research quantities. SG-DBR lasers have been produced at 1550 and 1600 nm for some times. Fundamental questions regarding the performance of the 1310 nm devices must be quantified. Standard metrics including the laser linewidth, amplitude modulation and frequency modulation responses are characterized. The intrinsic electrical parasitics of the laser diode segments and packaging are also investigated. In addition, testing fixture including a Thermal Electric Cooler (TEC) controller is for the characterization task. Measurements of these key metrics are essential to the enhancement of future devices, aiding in the optimization of more mature products.
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Duarte, Carlos Henrique Azevedo. "Programação da descarga de navios graneleiros de carvão: um estudo de caso na Companhia Siderúrgica do Pecém". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3136/tde-20092018-105541/.
Testo completoAbstract (sommario):
De acordo com Babu et al. (2015), o carvão mineral é um importante recurso natural devido à sua aplicação em várias atividades econômicas, como geração de energia, produção de aço, fabricação de cimento e produção de combustível líquido. Em função do custo e da baixa qualidade do carvão brasileiro (não coqueificável, na maioria das reservas, com elevado teor de cinzas e baixo poder calorífico), como apontado por Süffert (1997), as empresas brasileiras dos setores siderúrgico e termoelétrico necessitam importar este insumo, por via marítima. O desafio no planejamento da logística de suprimento desta matéria prima é garantir o abastecimento ao mínimo custo de estoque e de espera dos navios. A garantia de abastecimento passa por uma programação adequada da chegada e descarga dos navios. Quando a descarga de navios é uma operação gargalo, é necessário maior cuidado com a programação de recebimento, de maneira com que não haja atrasos, que causem a falta de produto, nem em muita antecipação, que podem significar excessivos tempo de fila para recebimento do material por falta de área para estocagem. Com o objetivo de se programar adequadamente a chegada de navios, de forma a evitar filas muito grandes e desabastecimento foi proposto um modelo de programação de chegada de navios, com base nos dados do complexo de Pecém. Este modelo proposto utilizou um buffer de tempo pré-determinado, que foi testado e validado através de simulação, com objetivo de minimizar os atrasos, de forma que possam ser absorvidos por um estoque de segurança, e as antecipações, de forma que não haja risco de falta de área de estocagem.According to Babu et al. (2015), coal is an important natural resource due to its application in various economic activities, such as power generation, steel production, cement manufacturing and liquid fuel production. Due to the cost and low quality of Brazilian coal (not coking, in most reserves, with high ash content and low calorific value), as pointed out by Süffert (1997), Brazilian companies in the steel and thermoelectric sectors need to import this input, by sea. The challenge in planning the logistics of supply of this raw material is to guarantee the supply at the minimum cost of inventory and waiting of the ships. The supply guarantee is subject to adequate scheduling of arrival and unloading of ships. When ship unloading is a bottleneck operation, greater care is required with the scheduling of receipt, so that there are no delays, which cause the lack of product, or in much anticipation, that can mean excessive queue time for receiving the shipment material for lack of storage area. In order to properly program, the arrival of ships, in order to avoid very large queues and shortage, a model for the arrival of ships was proposed, based on data from the Pecém complex. This proposed model used a pre-determined time buffer, which was tested and validated through simulation, in order to minimize the delays, so that they can be absorved by a security stock, and the anticipations, so that there is no risk lack of storage area.
36
Alghanmi, Sahar. "a"It was a dream, and it happens" : Saudi academics' discursive construction of blended learning integration : CHAT-inspired DBR". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/ait-was-a-dream-and-it-happensa-saudi-academicsa-discursive-construction-of-blended-learning-integration-chatinspired-dbr(d2c392ea-e98b-4412-b20c-940092a8e113).html.
Testo completoAbstract (sommario):
This study aims to understand how Saudi academics construct meaning about Blended Learning (BL) integration in their teaching activities. It grew from the importance of conducting baseline research that moves beyond repeating or reinforcing existing practices. Design-Based Research, matched with different stages of the evolution of Cultural Historical Activity Theory (CHAT-inspired DBR) was chosen as a methodological framework, because it presents activities as stages - analysis, design, implementation and reflection about principles - that enable access to more real-world practical data. This brings new insights into the development and knowledge generation experienced by academics in everyday practices and how they expand knowledge about BL as a new concept. The findings of this study contribute to a growing body of knowledge in the field of BL in higher education. It adds more understanding about academics' construction of the students' community, considering students' beliefs, motivation and emotional and social support at all levels as vital factors to ensure academics' success in integrating BL. Moreover, it demonstrates universities must implement specific institutional support as a way to minimise the gap between the real and anticipated practices. Well-organised and quality professional development helps sustained quality practice of BL; importantly, where universities' strategic orientation of BL contradicts academics' orientation, strategy needs to be reformed so academics can play an active role applying their creative version of BL practice. From the construction of tool-mediated BL it is evident that tools in academics' activities constitute a central discourse; as academics developed more knowledge they experienced conflicting professional needs between the vagueness of BL and the need to move on from traditional-based teaching practice. The lack of instructional design knowledge contributes to this feeling. Yet these academics, with minimum university support, were able to implement BL and its non-traditional approaches quite effectively. Furthermore, the transformative agency is shown to be an integral part of the activity, as it is the subjects who drive the activity. Academics' use of tool-mediated activities to break away from the particular frame of action is understood as transformative agency; thus they initiate commitment to transform their activity, embracing more possibilities for expansive learning. It can be said that BL as an object is an expansion of the academics' professional agency. Thus, this thesis's contribution to knowledge is twofold; first, it is hoped that the research findings will make a contribution to the implementation of BL in higher education. These findings will help stakeholders understand patterns of struggle caused by contradictions for academics planning to teach using BL and what kinds of support will be most beneficial. The study also has implications for policy-makers who influence legislation governing the kinds of faculty preparation appropriate for university students. The study suggests several areas to be investigated in the future. Second, it aims to methodologically advance baseline research through the integration of CHAT for different purposes in different stages of DBR, where multiple qualitative methods of data collection are employed to be responsive to the needs of these stages. In addition the analytical framework of Discursive Psychology (DP) adds to the understanding of the ways in which academics construct the meaning of BL, which in turn reveals what discourses surround how professional agency is practiced and can underpin the change from traditional to BL teaching. This analytical framework of DP helps reveals how contradictions are constructed within academics' discourses and how emotion and agency are formed from these contradictions.
37
Bozorgui, Shirin. "Modelisation des lasers semiconducteurs a reflecteur de bragg (dbr) : analyse des effets thermiques et du reseau a pas variable". Paris 11, 1997. http://www.theses.fr/1997PA112316.
Testo completoAbstract (sommario):
Ce travail porte sur la modelisation des lasers semiconducteurs a reflecteur de bragg (dbr). Un modele complet de ces lasers prenant en compte les non linearites du gain, les effets thermiques et la variation longitudinale du pas du reseau, permet d'evaluer l'ensemble des caracteristiques utiles en vue d'ameliorer leurs performances. Pour traiter les non linearites du laser, nous avons utilise la methode des fonctions de green en se basant sur l'approche proposee par duan. Afin d'incorporer les effets thermiques, nous avons adapte le modele de joyce et dixon au cas d'un laser dbr multielectrodes a geometrie ruban enterre. Les distributions, stationnaire et transitoire, de la temperature sont calculees analytiquement dans chaque section en utilisant respectivement les transformees de fourier et de laplace. La contribution des effets thermiques sur le detuning du mode principal et son influence sur l'augmentation de la bande passante et sur la diminuation de la largeur spectrale sont etudiees. La deuxieme partie de ce travail est consacree a l'etude theorique des lasers dbr a pas variable. Nous appliquerons, pour la premiere fois, la methode de courbure du guide d'onde aux diodes laser a reflecteur de bragg afin d'ameliorer les differentes caracteristiques de ce nouveau composant. L'amelioration de chaque caracteristique necessite une variation longitudinale appropriee du pas du reseau et par consequent la definition d'une nouvelle fonction de courbure. Dans ce but, nous introduisons une nouvelle procedure de recherche pour definir de nouvelles fonctions de courbure. Deux applications du reseau a pas variable sont etudiees : l'amelioration du taux de rejection des modes secondaires et de l'accordabilite du laser.
38
Ejemyr, Christoffer. "Modeling a Tunable Narrow Linewidth Laser". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-275689.
Testo completoAbstract (sommario):
In this report a model of a tunable narrow linewidth laser used for telecommunications is presented. The model uses both theoretical analysis and experimental data to create the mathematical models governing its behaviour and is aimed to be useful in a development environment with requirements on accuracy, efficient implementation and adaptability to future design. Results show that the model presented achieves high accuracy in both optical and electrical measurements. In summary the model could be useful in a development environment with further improvements in adaptability possible in the future.
39
Su, Chien-Chen, e 蘇乾禎. "Congestion-Driven Floorplan on DBL Representation". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/31823566479877559331.
Testo completoAbstract (sommario):
碩士中華大學
資訊工程學系碩士班
92
As VLSI technology reaches deep-sub micron dimensions and the application of SoC (System-on-Chip) design is general, the scale of VLSI circuit becomes more complex. A traditional area-driven floorplan become less important because of the decrease in cost of chip area. In floorplan stage, it is necessary for a successful chip design to develop an effective congestion analysis before global routing base on floorplan or placement information. To deal with multi-objective floorplan issue, we proposed double-bound-list (DBL) representation. DBL representation is more advanced than other representations (Ex. sequence pair, O-tree and B*-tree) and conform to the property of P-admissible because we can find out the total area and the adjacent relation between blocks with less memory. We also proposed hierarchical stair contour as our data structure to record the contour of floorplan and reduce the time complexity of data searching. In order to handle routability problem efficiently, hierarchical quad-grid model is proposed to estimate congestion. Quid-grid partition depend on wire density to avoid less accurate and more timing-consuming in 2-D static uniform grid-based model. A floorplan with congestion estimation before routing stage can reduce time complexity of routing procedure. The experimental results show that the method we proposed can decrease routing congestion with a few penalties for chip area.
40
廖祥智. "Multiobjective-Driven Floorplan on DBL Representation". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/10274946301721304758.
Testo completoAbstract (sommario):
碩士中華大學
資訊工程學系碩士班
91
Due to the coming of new system-on-chip (SoC) age, silicon-intellectual- property (SIP) modules become popular for modern chip design. Since SIP modules in one chip have provided by different companies or departments, it is very important for the development of SoC chip to integrate all the SIP modules into a single chip. On the other hand, to deal with the increasing complexity and various requirements of including chip performance, low power …etc of circuit, it also makes one floorplan to become more critical than even. However, an effective better floorplan approach depends on the data representation of floorplans, the estimation of cost function, and the development of floorplan improvement approach. In this paper, we discuss how to solve the non-slicing floorplan problem for multiple objectives. We use one data representation, named double -bound-list (DBL) for non-slicing floorplans. The DBL representation combines the advantages of representative popular representations such as sequence pair, O-tree and B*-tree. From the structure of the DBL representation, the floorplan area and the geometric adjacent relationship can be immediately found. In addition, the DBL representation uses less memory for the storage of one non-slicing floorplan. Now, there is not only the discussion of area requirement discussion for the non-slicing floorplan problem, but also the discussion of the high performance requirement, maximum routability requirement … etc. Especially, for routability requirement, there is more difficulty to guarantee the routabililty property in the routing phase due to the increasing complexity of net connections in circuit design. Based on the combination of multiple critical objectives, it takes much time to search optimal non-slicing floorplan results. Therefore, we use a data structure, named Hierarchical Stair Contour (HSC), to store the contour of an incremental floorplan, and improve the search efficiency. Finally, we develop a simulated-annealing-based floorplan approach on the proposed DBL and HSC data structure to obtain a final non-slicing floorpaln result. The experimental results show that the proposed approach can obtain better multiobjective floorplan results.
41
Tsai, Hong-Chang, e 蔡宏璋. "Cascaded Distributed-Bragg-Reflectors (DBRs) for Narrow-band Optical Filter". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/08587481103451166546.
Testo completoAbstract (sommario):
碩士國立交通大學
電子物理系
91
In this thesis, we propose a method to achieve a narrow band-pass optical filter using cascaded Distributed-Bragg-Reflectors (DBRs) and optical cavity, which construct a Fabry-Perot-like interferometry. Firstly, we analyze the traditional thin-film coating multi-layer optical filter by the use of transfer matrix method. The results can give us a guide how to design an optical narrow band-pass filter with nearly rectangular transmission spectrum. Secondly, by using the coupled-wave analyses of a volume hologram, we derive the scattering matrix method to analyses the diffraction properties of a reflection-type volume hologram. It provides us an extended matrix method to investigate the transmission characteristics of different cascaded structures of the volume holographic gratings. In experiment, we use PQ/PMMA photopolymer to fabricate volume holographic reflection-type gratings, and then the resonance cavities are fabricated by using thermal coating of MgF2 thin film. The theoretical and experimental results show that it is possible to achieve a narrow band-pass optical filter by using cascaded volume holographic gratings. However, the grating length, cascading structure and optical resonance cavity length must be chosen carefully such that the phase condition of Fabry-Perot-like structure can be matched.
42
Ping-Yu, Kuei, e 桂平宇. "Studies on Characteristics of Selectively Oxidized and Ion Implanted AlGaAs DBRs". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/44662512495791779051.
Testo completoAbstract (sommario):
博士國防大學中正理工學院
國防科學研究所
91
We discuss the effects of lateral wet oxidation and ion implantation on AlGaAs DBRs. The AlxGa1-xAs oxide is stable, amorphous, solid-phase (AlxGa1-x)2O3. For AlxGa1-xAs layers embedded in multi-layer structure, a stable oxidation process is achieved by precisely control the flow rate of carrier gas, oxidation temperature and oxidation period, the thickness of AlxGa1-xAs layers, etc. The oxidation rate of the DBR implanted with oxygen ions will be enhanced at the temperature range of 350~450℃. We thought the enhanced oxidation rate is dominantly resulted from the change of surface energy or strain between oxide layers and epi-layers. In addition, for the DBRs implanted with hydrogen, oxygen, silicon, or phosphorous ions, respectively, the central wavelength of reflectivity spectra will shift toward longer wavelength and the background reflectance is increased. According to our calculation and discussions, those are related to inter-diffusion of aluminum atoms in DBR. Finally, for the surface-emitting LED or RCLED with DBR structure, its optoelectronic properties are improved by additional process of lateral wet oxidation or ion implantation.
43
Yu-ChenLiu e 劉佑章. "An S-DBR Method for Dynamic Production System". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/61003210707668311243.
Testo completoAbstract (sommario):
碩士國立成功大學
工程科學系專班
99
In the make-to-order factories, operations scheduling is the core work of the production management. Especially in the metal processing industry, companies often face the uncertain processing capacity in the production process, operations scheduling becomes even more complicated and the ERP and the SCM systems usually cannot effectively keep the overall performance stable. Most studies on operations scheduling base their scheduling on fixed-premise machine outputs, which cannot meet the characteristics of such dynamic production systems. This study uses the Theory of Constraint and the Simplified Drum-Buffer-Rope method to develop an Advanced Planning and Scheduling system- APS, which strengthens the delivery forecast model and dynamically adjusts the production buffers to achieve more precise delivery date prediction for dynamic production systems. Verified by the actual operations of the metal processing industry, the APS is proved suitable for dynamic production environments. It improves the scheduling operation to response to the market demand and also strengthens the ability of production system adjustments in order to guarantee precise delivery dates and to maintain factory competitiveness.
44
Chen, Jen-jy, e 陳正智. "Temperature-Constrained Thermal-Driven Floorplan on DBL Representation". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/59331898607652134260.
Testo completoAbstract (sommario):
碩士中華大學
資訊工程學系碩士班
92
The development of the digit circuits in recent years has already entered into the ultra large-scale integrated circuit (ULSI) and System-on-Chip (SoC) era. The design of the chip becomes more and more complicated. In order to solve increased complexity, the concept of the silicon intellectual property (SIP) modules be extensively used. Hence, the SIP modules might be designed by a lot of different companies or offered with different departments. So, the companies which develop SIP modules can make good at their development and verification of products up to the best chip operation. Good modules may form better merger chip under the state of the optimization. In addition, the circuit design becomes complicated and the function diversification of customer's demand (such as high efficiency, the low power, etc.) causes the entire IC design flow to become to need long time to finish it. Hence, an effective better floorplan approach which depends on the good data representation of floorplans, the estimation of cost function, and the sampling of process improvement becomes more and more important. In this paper, we discuss how to reduce the temperature in a floorplan. Based on the DBL representation, we propose one Temperature-Driven floorplan, named Temperature-Constrained Thermal-Driven Floorplan on DBL Representation. The DBL representation combines the advantages of representative popular representation, such as Sequence Pair, O-tree and B*-tree. The data structure of the DBL representation which accords with the demand for P-admissible characteristic, can take polynomial time to get the adjacent relations between any pair of modules, and only need to use less memory for the storage of one floorplan. Now, there is not only the discussion of the area requirement for the floorplan problem, but also the discussion of the high efficiency requirement, maximum routability requirement, hot-spot distribution…etc. Under using less area and higher density of packaging, the increasing power consumption will lead to the rising temperature. So, we can prevent from overheated temperature to cause burning or abnormal operation on one chip. By using we proposed SA-based Temperature-Constrained Thermal-Driven Floorplan on DBL Representation, the experimental results shows that our approach reduce the chip temperature and with less storage.
45
Chou, Chien-Hsin, e 周見新. "Research on Line Design under the DBR System". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/63476544419541358871.
Testo completoAbstract (sommario):
碩士國立交通大學
工業工程與管理系
91
The purpose of this paper is to compare the benefits of two ways of production line design. One is traditional capacity balance design, and the other is DBR（Drum-Buffer-Rope, DBR）ramp-up protective capacity design. A good manufacturing system is enable to reduce production cycle time and raises the reliability of due day. In order to reach the objectives, manufacturing system must overcome the effects of various variable events, random fluctuation on production line, and minimum of the production cost as well. In view of the foregoing, traditional production system pursues capacity balance and places work-in-process (WIP) inventory in front of every machines to protect overall line, which will lead to production cycle time raise and lower the reliability of due day. Meanwhile, the DBR production system pursues flow balance and ramp-up capacity to protect overall line, ramp-up capacity investment will change by line bottleneck’s location. In general, ramp-up capacity investment will greater than traditional capacity balance, but it will show good results in lowering WIP, cycle time, and due day. As to the results, how many the benefits will be? In order to answer the benefits, this research builds a simulation production line (DBR and traditional system) with EM-Plant software to simulate and analyze the results of both production line design concepts. It shows that the DBR system gets better results than traditional system as a whole.
46
張志輝. "DBR-based Scheduling for Dual Capacity Constrained Resources". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/83864998820107494758.
Testo completo
47
Cesar, Julijan. "SiOx-SiCz MEMS-DBR-Based Tunable Optical Devices". Phd thesis, 2020. https://tuprints.ulb.tu-darmstadt.de/13563/1/2020-09-24_Cesar_Julijan.pdf.
Testo completoAbstract (sommario):
Wavelength tunable devices are required in many fields like spectroscopy of gases, biomedical absorption experiments, wavelength division multiplexing in optical data networks, among others. Usually the devices are limited by the technology implemented to change the transmitted frequencies and are specific to their usage scenario. Thus extending the regime in which a single device can function, will reduce the need for many different devices with a narrow application window. For example, having a tunable laser for telecommunication networks around 1550 nm, that can support both L- and C-bands (1530 to 1625 nm). It opens much more flexibility, either by applying new coding mechanisms that require wavelength switching. Or simply by reducing storage requirements, because only one type of device serves as hot-backup for all channels.
Investigation on tunable lasers on the basis of a VCSEL (vertical cavity surface emitting laser) in combination with a SiO-SiC MEMS-DBR, which offer up to 107 nm of tuning around 1550 nm, went on for more than two decades. It is time to overcome the material-specific limitation of those DBR materials. With a refractive index difference of 0.45 only 120 nm of high reflectivity around 1550 nm are supported by SiN and SiO.
In this work, silicon carbide (SiC) is introduced as a replacement for SiN to grow DBR stacks with a refractive index contrast of 1, when paired with SiO. This increases the reflectivity stopband by more than a factor of 2, while the number of layer pairs is reduced for similar maximum reflectivities. So, in the end, wider tuning and smaller devices are feasible.
The first step towards a MEMS-DBR tunable Fabry-Pérot VCSEL is investigating the behavior of the new material by processing passive filters based on the same principle. MEMS stands for micro-electro-mechanical system. Here a Farby-Pérot resonator consisting of two DBRs - one fixed, one movable - and an adjustable air-gap in between, enables continuous shifting of the resonant wavelength through displacement of the MEMS-DBR. After investigations on single layers deposited by low-temperature PECVD to enable compatibility with the active substrates, layer stacks are grown and structured into MEMS-DBRs. They can be actuated electro-thermally and electro-statically to tune the resonator cavity length and ultimately the transmission wavelength. First tests provided proof that the idea is working, but the tuning range was limited by the large cavity length.
To increase the free spectral range, the cavity length had to be reduced. By creating a Comsol Multiphysics model for SiO-SiC MEMS-DBR, harnessing packages for structural mechanics and electro-thermal physics, the number of experimental testing could be lowered. Changing several variables led to the need of reducing the lateral MEMS-size by at least a factor of 2. After a redesign of the photolithography masks, new small-sized MEMS were processed successfully, reducing the air-gap to the desired lengths of 1 to 4 micrometer.
Those new devices could be tuned over 250 nm, limited only by the measurement equipment. Moreover, increasing the number of layer pairs of the DBR decreased transmission linewidth below 30 pm (or 4 GHz) over a tuning range beyond 250 nm around 1550 nm.
MEMS-DBR surface-micro-machining technology was furthermore transferred to both photodiode and half-VCSEL substrates successfully. Both SiO-SiN and SiO-SiC MEMS-DBR tunable photodiodes were able to detect and separate two neighboring lasers in a dense wavelength division multiplexing grid with 100 GHz (or 0.8 nm) spacing.
SiO-SiC MEMS-DBR VCSELs showed a tuning range of only 57 nm around 1530 nm due to processing related issues. A much higher potential for wider tuning is available, but could not be achieved within the time frame of this work. Nevertheless, SiO-SiC MEMS-DBR VCSEL were found to be much less prone to temperature changes, considering emission wavelength shift, than SiO-SiN MEMS-DBR VCSEL published previously. This decreases environmentally induced temperature-dependent wavelength changes immensely.
48
Chen, Chun-yin, e 陳春源. "The Effect of Various Environment on S-DBR". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53127853956240929640.
Testo completoAbstract (sommario):
碩士國立交通大學
工業工程與管理系所
97
The purpose of this thesis is to examine and attempt to prove a combination of Dr Goldratt’s theories on Touch Time and Due Date concepts. In 2006,in his Strategy & Tactic Tree, Dr.Goldratt (Eliyahu M. Goldratt) brought up that S-DBR and Buffer Management could possibly provide better reliability. He also focused on Due Date Performance(DDP) for products in many factories . In 2008, in his Standing On The Shoulders Of Giants, he raised an important hypothesis. He suggested that using Drum-Buffer-Rope(DBR) , Touch Time should be decreased by about 10% compared to Quoted Lead Time(QLT) . This research has tried to combine Dr.Godratt’s two hypothesis by using both reasoning and simulation in order to get a good view of the process. It should be noted that this is the first time a thesis combines both of Dr Goldratt’s hypothesis. . The results of my experiments have indeed indicated that the combination of both could make it easier for the orders to be finished on time in a more effective way. In conclusion, this research points out the feasibility of the combination of both methods as well as the practical applications to a factory using this innovative approach.
49
Lin, Y. C., e 林裕承. "Study the Application of DBR in GaN LEDs". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/03279556080677983046.
Testo completoAbstract (sommario):
碩士大葉大學
電機工程學系
98
Due to the mature of epitaxy and process technologies, the application of nitride-based LEDs becomes more extensive. In order to improve the junction temperature and reduce the shading effect of electrodes, the flip-chip technology for LED package was also proposed and developed. The light will emit from substrate side surface for flip-chip packaged LEDs. The output intensity can be further enhanced if a reflector is deposited on the top surface of LEDs. In this thesis we have deposited a distributed Bragg reflector (DBR) on the top surface of LEDs to improve the output light intensity. The DBR is composed of SiO2 and TiO2. The reflectivity and transmittance were measured for the DBR samples with different pairs. From the measured results, a reflectivity of 91% at wavelength range of 450 ~ 470 nm was obtained from the DBR samples with 7.5 pairs. The light intensity emitted from top surface of the LED with DBR was reduced about 82%. Oppositely, the light intensity emitted from substrate side surface was enhanced about 30%.
50
Chang, Jia-Ging, e 張家鈞. "Enhancing the Application of S-DBR within MTO Environment". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/995gee.
Testo completoAbstract (sommario):
碩士國立交通大學
工業工程與管理系所
96
In 2000, Eli Schragenheim and H. William Dettmer raised the idea of Simplified Drum-Buffer-Rope (S-DBR). They claimed that the market demand was the constraint of production system. They considered that there was no need to do the capacity constrained resource (CCR) scheduling if we could obey the CCR’s Planned Load (PL), which included well-organized confirm orders, release orders and priority management. That would make production management become easier. After developing and practicing for six or seven years, Schragenheim brought up the implementation of S-DBR more practically in 2006. He also pointed out that S-DBR still kept the advantages of DBR, and it could satisfy the Due Date Performance (DDP) at the same time. In this way, this research tried to verify Schragenheim’s assumption originally by reasoning, Job Shop game and simulation. The result showed that S-DBR could make the orders finished in time effectively. However, there are other production environments practically. In order to make sure the feasibility of S-DBR and figure out some doubts on S-DBR, this research discussed five issues further; inclusive of (1) the position of CCR’s influence on due-date among manufacturing process, (2) the influence of CCR drift, (3) batching, (4) order inserting, and (5) reentry flow environment. Furthermore, to enhance the protection and competency on due-date of S-DBR, this research also raised some ways to reinforce the ability of S-DBR when facing the variety of market demand and production environment.