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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Funcionalização do 3,4,6-tri-O-acetil-D-glucal com sais de organotrifluoroboratos de potássio e reações de click chemistry para a geração e funcionalização de triazóis / Functionalization of 3,4,6-tri-O-acetyl-D-glucal with potassium organotrifluoroborate salts and click chemistry reactions for the generation and functionalization of triazoles.

Nathalia Cristina da Silva e Silva 22 February 2013 (has links)
No presente trabalho, foi desenvolvida uma metodologia sintética para a funcionalização de um monossacarídeo derivado da D-glicose através do Rearranjo de Ferrier, utilizando-se um sal de organotrifluoroborato de potássio como nucleófilo. Em seguida, foi feita a reação de cicloadição azida-acetileno com cobre, através de estratégias simples e eficientes, que seguem a filosofia da click chemistry, permitindo a preparação de uma série de compostos com grande diversidade estrutural, possuindo dois anéis heterocíclicos e diversos substituintes, com promissora atividade biológica. Dando continuidade ao projeto, foi feita a metanólise dos grupamentos acetila, com carbonato de potássio e metanol. Assim, as novas moléculas adquirem maior hidrofilicidade e podem ser enviadas para novos testes biológicos, para fins de comparação com as anteriores. A partir dos compostos desprotegidos, foi feita a mesilação seletiva da hidroxila primária do açúcar e a substituição com selenolato de sódio, com a obtenção de seleno-carboidratos inéditos. Em uma segunda etapa do trabalho, exploramos a reatividade do núcleo triazólico, com a reação de troca Te/Li seguida de captura por eletrófilo. O material de partida foi sintetizado a partir do fenil acetileno. Com o triazol telurado em mãos, partimos para as reações de troca e captura por eletrófilo. Utilizamos diferentes tipos de eletrófilos, como aldeídos, cetonas, iodetos, dentre outros. / We developed a synthetic methodology for the functionalization of a monosaccharide derived from D-glucose, using the Ferrier rearrangement with a potassium organotrifluoroborate salt as the nucleophile. This way, a series of coumpounds with high structural diversity and two heterocyclic rings having different substituents were produced, using the azide-acetylene cycloaddition reaction. Through this simple and efficient methodology, that follows the \"click chemistry\" philosophy, we could synthesize molecules with promising biological activity. Continuing the project, we performed the methanolysis of the acetyl groups, with potassium carbonate and methanol. Thus, the new molecules become more hydrophilic and could be sent to new biological tests, for a comparison with the previous ones. From the deprotected compounds, we were able to mesilate the primary hydroxyl and substitute it with sodium selenolate, obtaining novel selenium-carbohydrates. In a second part of our work, we were able to exploit the triazole reactivity trough the Te/Li exchange reaction followed by the electrophile capture. The starting material was obtained from phenyl acetylene. With the teluratte in our hands, we set out to the exchange reactions, using several types of electrophiles, such as aldehydes, ketones, iodide, among others.
142

Mechanical, Structural, Thermal and Electrical Studies on Indium and Silver Doped Ge-Te Glasses having Possible PCM Applications

Sreevidya Varma, G January 2014 (has links) (PDF)
The Science behind amorphous Chalcogenide materials opened up new technologies in the arena of Phase Change Memories. The Ovonic universal phase change memory is called universal because it can replace flash memory, DRAM and SRAM. These are not only basic computer memory devices but also are becoming the driving force for the ongoing revolutionary growth of cell phones and other mobile devices, which are in desperate need of memory providing higher density, faster speed and lower power consumption. In this thesis, compositional dependence of various properties of different chalcogenide glasses are investigated, to explore the possibility of their application in Phase Change Memories. Efforts are also made to understand the effect of rigidity and extended rigidity transition on the composition dependence of properties investigated. This thesis comprises of 9 chapters; a brief summary is given below. Chapter 1 deals with fundamental aspects of amorphous semiconductors with a particular reference to chalcogenide glasses. The advantages and applications of chalcogenide glasses are also described. Chapter 2 outlines preparation and characterization of the glasses investigated. The sample preparation and various experimental setup used in the present thesis work like Raman Scattering, Nanoindentation, Alternating Differential Scanning Calorimetry (ADSC), Photo-thermal Deflection Spectroscopy (PDS), Electrical Switching are summarized here. Chapter 3 deals with Micro-Raman studies in Ge15Te85-x Inx Glasses. Micro-Raman studies reveal that as-quenched Ge15Te85-xInx samples exhibit two prominent peaks, at 123 and 155 cm-1. In thermally annealed samples, the peaks at 120 cm-1 and 140 cm-1, which are due to crystalline Te, emerge as the strongest peaks. The Raman spectra of polished samples are similar to those of annealed samples, with strong peaks at 123 cm-1 and 141 cm-1. The spectra of lightly polished samples outside the thermally reversing window resemble those of thermally annealed samples; however, the spectra of glasses with compositions in the thermally reversing window resemble those of as-quenched samples. This observation confirms the earlier idea that compositions in the thermally reversing window are non-ageing and are more stable. Chapter 4 explains nanoindentation studies undertaken on Ge15Te85-xInx glasse (1 ≤ x ≤ 11). Nanoindentation studies on Ge15Te85-xInx glasses indicate that the hardness and elastic modulus of these glasses increase with indium concentration. While a pronounced plateau is seen in the elastic modulus in the composition range 3 ≤ x ≤ 7, the hardness exhibits a change in slope at compositions x = 3 and x = 7. Also, the density exhibits a broad maximum in this composition range. The observed changes in the mechanical properties and density are clearly associated with the thermally reversing window in Ge15Te85-xInx glasses in the composition range 3 ≤ x ≤ 7. In addition, a local minimum is seen in density and hardness around x = 9, the chemical threshold of the system. Chapter 5 deals with crystallization kinetics of Ge15Te85-xInx glasses. The crystallization kinetics of Ge15Te85Inx glasses have been studied by non-isothermal method. The composition dependence of Tg and Tc at different heating rates, is investigated. The activation energy of crystallization is calculated using the Kissinger’s plot. It is found that the composition dependence of the glass transition temperature, Tg and the crystallization temperature, Tc, the activation energy of crystallization, Ec, and the stability factor, (ΔT= Tc-Tg) exhibit specific signatures of intermediate phase in the composition rang 3 ≤ x ≤ 7 and Chemical Threshold at x = 9. Chapter 6 explains Alternating Differential Scanning Calorimetric and XRD studies on silver doped Ge15Te80In5 glasses. X-ray diffraction studies on quaternary Ge15Te80-xIn5Agx glasses (2 ≤ x ≤ 24) reveal the presence of Te, GeTe, Ag8GeTe6, AgTe, In2Te3 and In4Te3. Thermal studies on quaternary Ge15Te80-xIn5Agx glasses exhibit signatures of Intermediate Phase (IP) in the variation of Tg, ∆HNR and ∆Cp with Ag addition in the composition range 8 ≤ x ≤ 16. The composition x = 16 has been identified to be the Chemical Threshold (CT) based on the saturation of flexible Ag-Te bonds. Micro-Raman, molar volume, thermal diffusivity studies on Ge15Te80-xIn5Agx glasses reveal a clear evidence of intermediate phase in the composition range 8 ≤ x ≤ 16 as depicted in the ADSC studies. Chapter 7 deals with Micro-Raman studies on as-quenched Ge15Te80-xIn5Agx glasses reveal the presence of tetrahedral structural units. Further, the Raman peak positions are found to shift with silver addition. In addition, specific signatures of the Intermediate Phase (IP) are observed in the composition dependence of Raman frequencies and corresponding intensities of different modes in the composition range, 8 ≤ x ≤ 16. In thermally annealed samples, the observed Raman peaks can be attributed to crystalline tellurium and silver lattice vibrational modes; significant increase in intensity is observed at 93 and 141cm-1 with silver addition in annealed samples, suggesting an increase in silver lattice vibrational modes. Also, the compositional dependence of density, molar volume and thermal diffusivity confirms the presence of the intermediate phase. Chapter 8 contains the current-voltage characteristics and electrical switching behavior of Ge15Te80-xIn5Agx glasses. The glasses are found to exhibit memory type switching for 3mA current in the voltage range 70 -120 V, for a sample thickness 0.3 mm. But when the current is lowered to 1mA the samples exhibit threshold switching. The compositional studies indicate the presence of an intermediate phase in the composition range 8 ≤ x ≤ 16. SET-RESET studies have been carried out using a triangular pulse of 6 mA amplitude for SET and 21 mA amplitude for RESET for a sample thickness 0.3 mm. Raman studies on SET and RESET indicates SET state resemble annealed samples and RESET state resemble as-quenched samples. It is interesting to note that the samples in the intermediate phase, especially compositions at x =10, 12, 14 withstand more set-reset cycles. This indicates compositions in the intermediate phase are suitable for PCM devices. Chapter 9 summarizes the significant results obtained and explains the scope of this thesis.
143

Organoteluretos vinílicos e alquílicos O-funcionalizados: aplicação na síntese assimétrica de γ-butirolactonas bioativas e feromônios / Vinyl and alkyl O-functionalized organotellurides: application in the asymmetric synthesis of bioactive γ-butyrolactones and pheromones

Ferrarini, Renan dos Santos 02 December 2011 (has links)
A presente tese de doutorado descreve a integração de metodologias sintéticas da química de organoteluretos desenvolvidas nos últimos anos pelo grupo. Especialmente a hidroteluração de cetonas α,β-insaturadas, a resolução cinética enzimática de hidróxi-teluretos e a reação de troca Te/Li. Tais metodologias, empregadas em sequência, possibilitaram a obtenção de blocos sintéticos versáteis na preparação de reagentes organometálicos funcionalizados e enantiomericamente enriquecidos. Esse protocolo mostrou-se eficiente na preparação de uma variedade de produtos naturais, como por exemplo, feromônios de insetos-praga e butirolactonas com atividades biológicas relevantes. O trabalho foi dividido em duas partes. Estudou-se a reatividade e o emprego de organoteluretos alquílicos (sp3) e vinílicos (sp2) O-funcionalizados, na síntese dos produtos naturais citados acima. Na primeira parte do trabalho estudou-se a utilização de organoteluretos vinílicos. Esta classe de compostos foi preparada a partir da hidroteluração de alquinonas, os intermediários carbonílicos foram reduzidos com NaBH4, fornecendo uma mistura racêmica de hidróxi-teluretos vinílicos. Esses compostos foram submetidos à resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto à excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção de hidróxi-teluretos vinílicos enantiomericamente enriquecidos em até 96% e.e. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion vinílico de lítio. Pela eletronegatividade do átomo de lítio possibilitar vários tipos de transmetalações, esse intermediário é de grande valia em síntese orgânica. Na presença de eletrófilos, como CO2, esse diânion apresentou boa reatividade, gerando α-alquil-γ-butenolidas, após hidrólise em meio ácido. Tais butenolidas, constituíram-se como esqueleto avançado na síntese da (+)-Blastimicinona, (-)-Blastimicinolactol, (+)-Antimicinona, (-)-NFX-2 e todos os isômeros da Acaterina, em bons rendimentos globais. Esses compostos apresentam atividades antifúngicas, antitumorais e inibitórias de enzimas relacionadas à Arteriosclerose, respectivamente. Na segunda parte do trabalho estudou-se a utilização de um organotelureto alquílico em particular. Obtido a partir da hidroteluração da metil-vinil-cetona e redução in situ, do intermediário carbonílico. A mistura racêmica obtida foi resolvida através de resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto a excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção dos dois enantiômeros do respectivo hidróxi-telureto alquílico em excessos enantioméricos de até 99%. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion alquílico de lítio que foi transmetalado para uma série organocupratos. Ao reagi-lo com tosilatos específicos e realizar work-up com Ac2O, obteve-se uma série de feromônios de insetos-praga (C. pisi, M. destructor e D. mulleri) em bons rendimentos. / This PhD thesis describes the integration of synthetic methodologies involving organotellurides chemistry developed in recent years by the group, especially hydrotelluration of α,β-unsaturated ketones, enzymatic kinetic resolution of hydroxytellurides and Te/Li exchange reaction. These methods, used together, made it possible to obtain versatile synthetic blocks which were used in the preparation of functionalized and enantiomerically enriched organometallic reagents, featuring a synthetic key step in preparing a variety of natural products, such as Insect Pheromones and Butyrolactones with relevant biological activities. This work was divided into two parts. We studied the reactivity and the application of alkyl (sp3) and vinyl (sp2) O-functionalized organotellurides, in the synthesis of natural products cited above. In the first part of the work we studied the use of vinyl organotellurides. This class of compounds was prepared from hydrotelluration of alkynones, carbonyl intermediates were reduced with NaBH4 giving a racemic mixture of hydroxy-vinyl tellurides. These compounds were subjected to enzymatic kinetic resolution, using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good yielding hydroxy-vinylic tellurides with enantiomeric excesses up to 96%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4-(C,O) vinyl dianion. According to the characteristics of the electronegative atom of lithium, this intermediate is of great value in organic synthesis. In the presence of electrophiles such as CO2 showed good reactivity generating α-alkyl-γ-butenolides after acid hydrolysis. Such Butyrolactones constituted themselves as a skeleton for the synthesis of advanced (+)-Blastmycinone, (-)-Blastmycinolactol, (+)-Antimycinone, (-)-NFX-2 and all isomers of Acaterin in good overall yields. These compounds have antifungal and antitumor activity and inhibitory enzymes related to arteriosclerosis, respectively. In the second part of the work we studied the use of a specific alkyl organotelluride obtained by hydrotelluration of methyl vinyl ketone and in situ reduction of carbonyl intermediate by NaBH4. The racemic mixture was submitted to enzymatic kinetic resolution using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good, allowing to obtain the two enantiomers of the corresponding hydroxy-alkyl telluride with enantiomeric excess of up to 99%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4- (C,O) alkyl dianion that was used for the transmetallation for several organocuprate which when reacted with tosylates and perform specific work-up provided a number of pheromones of pest insects (C. pisi, M. destructor and D. mulleri) in good yields.
144

Organoteluretos vinílicos e alquílicos O-funcionalizados: aplicação na síntese assimétrica de γ-butirolactonas bioativas e feromônios / Vinyl and alkyl O-functionalized organotellurides: application in the asymmetric synthesis of bioactive γ-butyrolactones and pheromones

Renan dos Santos Ferrarini 02 December 2011 (has links)
A presente tese de doutorado descreve a integração de metodologias sintéticas da química de organoteluretos desenvolvidas nos últimos anos pelo grupo. Especialmente a hidroteluração de cetonas α,β-insaturadas, a resolução cinética enzimática de hidróxi-teluretos e a reação de troca Te/Li. Tais metodologias, empregadas em sequência, possibilitaram a obtenção de blocos sintéticos versáteis na preparação de reagentes organometálicos funcionalizados e enantiomericamente enriquecidos. Esse protocolo mostrou-se eficiente na preparação de uma variedade de produtos naturais, como por exemplo, feromônios de insetos-praga e butirolactonas com atividades biológicas relevantes. O trabalho foi dividido em duas partes. Estudou-se a reatividade e o emprego de organoteluretos alquílicos (sp3) e vinílicos (sp2) O-funcionalizados, na síntese dos produtos naturais citados acima. Na primeira parte do trabalho estudou-se a utilização de organoteluretos vinílicos. Esta classe de compostos foi preparada a partir da hidroteluração de alquinonas, os intermediários carbonílicos foram reduzidos com NaBH4, fornecendo uma mistura racêmica de hidróxi-teluretos vinílicos. Esses compostos foram submetidos à resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto à excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção de hidróxi-teluretos vinílicos enantiomericamente enriquecidos em até 96% e.e. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion vinílico de lítio. Pela eletronegatividade do átomo de lítio possibilitar vários tipos de transmetalações, esse intermediário é de grande valia em síntese orgânica. Na presença de eletrófilos, como CO2, esse diânion apresentou boa reatividade, gerando α-alquil-γ-butenolidas, após hidrólise em meio ácido. Tais butenolidas, constituíram-se como esqueleto avançado na síntese da (+)-Blastimicinona, (-)-Blastimicinolactol, (+)-Antimicinona, (-)-NFX-2 e todos os isômeros da Acaterina, em bons rendimentos globais. Esses compostos apresentam atividades antifúngicas, antitumorais e inibitórias de enzimas relacionadas à Arteriosclerose, respectivamente. Na segunda parte do trabalho estudou-se a utilização de um organotelureto alquílico em particular. Obtido a partir da hidroteluração da metil-vinil-cetona e redução in situ, do intermediário carbonílico. A mistura racêmica obtida foi resolvida através de resolução cinética enzimática, empregando a lipase, disponível comercialmente, Novozyme® 435. Os resultados, quanto a excessos enantioméricos e rendimentos foram bons, possibilitando a obtenção dos dois enantiômeros do respectivo hidróxi-telureto alquílico em excessos enantioméricos de até 99%. Na etapa seguinte, efetuou-se a reação de troca Te/Li, gerando um reagente organometálico funcionalizado, denominado 1,4-(C,O) diânion alquílico de lítio que foi transmetalado para uma série organocupratos. Ao reagi-lo com tosilatos específicos e realizar work-up com Ac2O, obteve-se uma série de feromônios de insetos-praga (C. pisi, M. destructor e D. mulleri) em bons rendimentos. / This PhD thesis describes the integration of synthetic methodologies involving organotellurides chemistry developed in recent years by the group, especially hydrotelluration of α,β-unsaturated ketones, enzymatic kinetic resolution of hydroxytellurides and Te/Li exchange reaction. These methods, used together, made it possible to obtain versatile synthetic blocks which were used in the preparation of functionalized and enantiomerically enriched organometallic reagents, featuring a synthetic key step in preparing a variety of natural products, such as Insect Pheromones and Butyrolactones with relevant biological activities. This work was divided into two parts. We studied the reactivity and the application of alkyl (sp3) and vinyl (sp2) O-functionalized organotellurides, in the synthesis of natural products cited above. In the first part of the work we studied the use of vinyl organotellurides. This class of compounds was prepared from hydrotelluration of alkynones, carbonyl intermediates were reduced with NaBH4 giving a racemic mixture of hydroxy-vinyl tellurides. These compounds were subjected to enzymatic kinetic resolution, using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good yielding hydroxy-vinylic tellurides with enantiomeric excesses up to 96%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4-(C,O) vinyl dianion. According to the characteristics of the electronegative atom of lithium, this intermediate is of great value in organic synthesis. In the presence of electrophiles such as CO2 showed good reactivity generating α-alkyl-γ-butenolides after acid hydrolysis. Such Butyrolactones constituted themselves as a skeleton for the synthesis of advanced (+)-Blastmycinone, (-)-Blastmycinolactol, (+)-Antimycinone, (-)-NFX-2 and all isomers of Acaterin in good overall yields. These compounds have antifungal and antitumor activity and inhibitory enzymes related to arteriosclerosis, respectively. In the second part of the work we studied the use of a specific alkyl organotelluride obtained by hydrotelluration of methyl vinyl ketone and in situ reduction of carbonyl intermediate by NaBH4. The racemic mixture was submitted to enzymatic kinetic resolution using the lipase NovozymeTM 435. The results, as the yields and enantiomeric excesses were good, allowing to obtain the two enantiomers of the corresponding hydroxy-alkyl telluride with enantiomeric excess of up to 99%. In the next step we performed the Te/Li exchange reaction, generating a functionalized organometallic reagent, known as lithium 1,4- (C,O) alkyl dianion that was used for the transmetallation for several organocuprate which when reacted with tosylates and perform specific work-up provided a number of pheromones of pest insects (C. pisi, M. destructor and D. mulleri) in good yields.
145

Transmission DynamicsModelling : Gear Whine Simulation Using AVL Excite

Mehdi Pour, Reza January 2018 (has links)
Nowadays, increasing pressure from legislation and customer demands in the automotive industry are forcing manufacturers to produce greener vehicles with lower emissions and fuel consumption.As a result, electrified and hybrid vehicles are a growing popular alternative to traditional internal combustion engines (ICE). The noise from an electric vehicle comes mainly from contact between tyres and road, wind resistance and driveline. The noise emitted from the driveline is for the mostpart related to the gearbox. When developing a driveline, it is a factor of importance to estimate the noise radiating from the gearbox to achieve an acceptable design.Gears are used extensively in the driveline of electric vehicles. As the gears are in mesh, a main intrusive concern is known as gear whine noise. Gear whine noise is an undesired vibroacoustic phenomenon and is likely to originate through the gear contacts and be transferred through themechanical components to the housing where the vibrations are converted into airborne and structure-borne noise. The gear whine noise originates primarily from the excitation coming from transmission error (TE). Transmission error is defined as the difference between the ideal smoothtransfer of motion of a gear and what is in practice due to lack of smoothness.The main objective of this study is to simulate the vibrations generated by the gear whine noise in an electric powertrain line developed by AVL Vicura. The electric transmission used in this study provides only a fixed overall gear ratio, i.e. 9.59, under all operation conditions. It is assumed thatthe system is excited only by the transmission error and the mesh stiffness of the gear contacts. In order to perform NVH analysis under different operating conditions, a multibody dynamics model according to the AVL Excite program has been developed. The dynamic simulations are thencompared with previous experimental measurements provided by AVL Vicura.Two validation criteria have been used to analyse the dynamic behaviour of the AVL Excite model: signal processing using the FFT method and comparison with the experimental measurements.The results from the AVL Excite model show that the FFT criterion is quite successful and all excitation frequencies are properly observed in FFT plots. Nevertheless, when it comes to the second criterion, as long as not all dynamic parameters of the system such as damping or stiffnesscoefficients are provided with certainty in the model, it is too difficult to investigate the accuracy of the AVL Excite model. Another investigation is a numerical design study to analyses how the damping coefficients influence the response. After reducing the damping parameters, the results show that the housing and bearings have the highest influence on the response. If more acceptable results are desired,future studies must be concentrated on these to obtain more acceptable damping values. / För närvarande tvingar ökat tryck från lagstiftning och kundkrav inom bilindustrin tillverkarna attproducera grönare fordon med lägre utsläpp och bränsleförbrukning. Som ett resultat ärelektrifierade och hybridfordon ett växande populärt alternativ till traditionellaförbränningsmotorer (ICE). Bullret från ett elfordon kommer främst från kontakten mellan däckoch väg, vindmotstånd och drivlinan. Bullret från drivlinan är i huvudsak relaterat till växellådan.Vid utveckling av en drivlina är det av betydelse att uppskatta bullret från växellådan för att uppnåen acceptabel design.Utväxlingar används i stor utsträckning i elfordons drivlina. Eftersom kugghjulen är i kontaktuppstår ett huvudproblem som är känt som ett vinande ljud från kugghjulskontakten.Kugghjulsljud är ett oönskat vibro-akustiskt fenomen och uppstår sannolikt på grund avkugghjulkontakterna och överförs via de mekaniska komponenterna till växellådshuset därvibrationerna omvandlas till luftburet och strukturburet ljud. Kugghjulsljudet härstammarhuvudsakligen från exciteringen som kommer från transmissionsfel (TE) i kugghjulskontakten.Överföringsfelet definieras som skillnaden mellan den ideala smidiga rörelseöverföringen hoskugghjulen och rörelsen som sker i verkligheten på grund av ojämnheter.Huvudsyftet med denna studie är att simulera vibrationerna som genereras avkugghjulskontakterna i en elektrisk drivlina utvecklad av AVL Vicura. Den elektriska drivlinan somanvänds i denna studie har endast ett fast utväxlingsförhållande, dvs 9,59, för alladriftsförhållanden. Det antas att systemet är exciterat endast av överföringsfelet och kugghjulensstyvhet i kuggkontakterna. För att kunna utföra NVH-analys under olika driftsförhållanden har enstelkroppsdynamikmodell utvecklats med hjälp av programmet AVL Excite. De dynamiskasimuleringarna jämförs sedan med tidigare experimentella mätningar som tillhandahålls av AVLVicura.Två valideringskriterier har använts för att analysera det dynamiska beteendet hos AVL Excitemodellen:signalbehandling med FFT-metoden och jämförelse med experimentella mätningar.Resultaten från AVL Excite-modellen visar att FFT-kriteriet är ganska framgångsrikt och allaexcitationsfrekvenser observeras korrekt i FFT-diagrammen. Men när det gäller det andra kriteriet,så länge som inte alla dynamiska parametrar i systemet, såsom dämpnings- ellerstyvhetskoefficienter, är tillförlitliga i modellen, är det för svårt att undersöka exaktheten hos AVLExcite-modellen.En annan undersökning som utförts är en numerisk designstudie för att analysera hurdämpningskoefficienterna påverkar responsen. Efter minskning av dämpningsparametrarna visarresultaten att växellådshus och lager har störst inflytande på resultatet. Om mer acceptabla resultatär önskvärda måste framtida studier koncentreras på dessa parametrar för att uppnå mer acceptabladämpningsvärden.
146

Thermal Characterization of In-Sb-Te thin films for Phase Change Memory Application / Caractérisation thermique des couches minces de l’IST pour des applications de mémoire à changement de phase

Nguyen, Huu tan 10 July 2015 (has links)
Les matériaux à changement de phase (PCM) sont utilisés pour la réalisation de mémoire non volatile. Ces matériaux possèdent la particularité de passer d’un état cristallin à un état amorphe à l’aide d’une impulsion de chaleur, créant ainsi un processus propre au stockage de l’information. Les PCMs sont généralement basés sur des composés ternaires de type Ge-Sb-Te (GST) avec une température de transition de l’ordre de 125°C, rendent ces matériaux inutilisable dans le domaine de l’automobile et pour des applications militaires. Pour contourner cette limitation, le GST est remplacé par le composé In-Sb-Te (IST) possèdent une température de transition plus élevé et un temps de transition beaucoup plus rapide (nanoseconde). Les propriétés thermiques de l’IST et de ses interfaces au sein de la cellule PCM peuvent influencer la température de transition. C’est pourquoi la mesure de la conductivité thermique nous donnera une estimation de la valeur de cette transition.Différentes techniques ont été misent en oeuvre pour mesurer la conductivité thermique des couches minces d’IST en fonction de la concentration en Te, à savoir ; la radiométrie photo-thermique modulée (MPTR) et la méthode 3ω dans une gamme de température allant de l’ambiant jusqu'à 550°C.Les résultats obtenus par les deux techniques de caractérisation thermiques démontrent que la conductivité thermique de l'IST diminue lorsque l'on augmente la teneur en Te. L'augmentation de la teneur en Te pourrait donc conduire à un alliage thermiquement plus résistif, qui est censé apporter l'avantage d'un flux de chaleur plus confiné et limiter la cross-talk thermique dans le dispositif de mémoire à changement de phase. / Phase change memories (PCM) are typically based on compounds of the Ge-Sb-Te (GST) ternary system. Nevertheless, a major drawback of PCM devices is the failure to fulfill automotive-level or military-grade requirements (125°C continuous operation), due to the low crystallization temperature of GST. To overcome this limitation, alloys belonging to the In-Sb-Te (IST) system have been proposed, which have demonstrated high crystallization temperature, and fast switching. Thermal properties of the chalcogenide alloy and of its interfaces within the PCM cell can influence the programming current, reliability and optimized scaling of PCM devices. The two methods, namely: 3ω and Modulated Photothermal Radiometry (MPTR) technique was implemented to measure the thermal conductivity of IST thin films as well as the thermal boundary resistance at the interface with other surrounding materials (a metal and a dielectric). The experiment was carried outin situ from room temperature up to 550oC in order to investigate the intrinsic thermal properties at different temperatures and the significant structural rearrangement upon the phase transition.The results obtained from the two thermal characterization techniques demonstrate that the thermal conductivity of IST decreases when increasing the Te content. Increasing the Te content could thus lead to a more thermally resistive alloy, which is expected to bring the advantage of a more confined heat flow and limiting the thermal cross-talk in the phase change memory device.
147

Enabling traffic engineering over segment routing / Rendre possible l'ingénierie de trafic dans les réseaux avec routage par segment

Guedrez, Rabah 12 December 2018 (has links)
La majorité des grands opérateurs utilise la technologie MPLS pour gérer leur réseau via des protocoles de signalisation et de distributions de labels. Or, ces protocoles sont complexes à déployer, à maintenir et la résolution des pannes est souvent très difficile. L'IETF a initié la standardisation d'une architecture de routage par segments (Segment Routing) s'appuyant sur un plan de contrôle simple, léger, facile à gérer et instanciée sur MPLS ou IPv6. Cette architecture repose sur le concept de routage à la source, dans lequel l'en-tête des paquets transporte les indications du chemin à suivre pour atteindre sa destination. Adapté aux cas d'usages simples et offrant nativement une résistance aux pannes, les cas d'usages plus complexes exigent de résoudre des verrous technologiques pour lesquels nous proposons plusieurs solutions. Dans cette thèse effectuée au sein d'Orange Labs, nous nous sommes intéressés à l'instanciation de l'architecture Segment Routing sur le plan de transfert MPLS et plus particulièrement à l'ingénierie de trafic, notamment avec réservation de ressources. Nous avons proposé des solutions aux problèmes liés à la limitation matérielle des routeurs actuels ne permettant pas l'expression de tous les chemins contraints. Ce travail est divisé en deux parties : (i) la proposition d'algorithmes de calcul et d'encodage de chemins de routage par segment afin de contourner les limitations matérielles. (ii) la définition des exigences architecturales et la construction d'une preuve de concept fonctionnelle. Enfin, cette thèse propose de nouvelles pistes d'études afin de consolider les outils d'ingénierie de trafic pour le routage par segment. / Most major operators use MPLS technology to manage their network via signalling and label distribution protocols. However, these protocols are complex to deploy, maintain and troubleshooting is often very difficult. The IETF has initiated the standardization of a segment routing architecture based on a simple control plane, lightweight, easyto-manage and instantiated on MPLS or IPv6. This architecture is based on the concept of source routing, in which the packet header carries the indications of the path to follow to reach its destination. Suitable for simple use cases and natively resistant to failure, more complex use cases require the resolution of technological issues for which we offer several solutions.In this thesis carried out within Orange Labs, we were interested in the instantiation of the Segment Routing architecture on the MPLS transfer plan and more particularly in traffic engineering, particularly with resource reservation. We have proposed solutions to the problems related to the hardware limitation of current routers that do not allow the expression of all constrained paths. This work is divided into two parts : (i) the proposal of algorithms for computing and encoding segment routing paths in order to bypass hardware limitations. (ii) the definition of architectural requirements and the construction of a functional proof of concept. Finally, this thesis proposes new research issues to consolidate traffic engineering tools for segment routing.
148

Drift-Type Waves in Rotating Tokamak Plasma

Asp, Elina January 2003 (has links)
<p>The concept of energy production through the fusion of two light nuclei has been studied since the 1950’s. One of the major problems that fusion scientists have encountered is the confinement of the hot ionised gas, i.e. the plasma, in which the fusion process takes place. The most common way to contain the plasma is by using at magnetic field configuration, in which the plasma takes a doughnut-like shape. Experimental devices of this kind are referred to as tokamaks. For the fusion process to proceed at an adequate rate, the temperature of the plasma must exceed 100,000,000C. Such a high temperature forces the plasma out of thermodynamical equilibrium which plasma tries to regain by exciting a number of turbulent processes. After successfully quenching the lager scale magnetohydrodynamic turbulence that may instantly disrupt the plasma, a smaller scale turbulence revealed itself. As this smaller scale turbulence behaved contrary to the common theory at the time, it was referred to as anomalous. This kind of turbulence does not directly threaten existents of the plasma, but it allows for a leakage of heat and particles which inhibits the fusion reactions. It is thus essential to understand the origin of anomalous turbulence, the transport it generates and most importantly, how to reduce it. Today it is believed that anomalous transport is due to drift-type waves driven by temperature and density inhomogeneities and the theoretical treatment of these waves is the topic of this thesis.</p><p>The first part of the thesis contains a rigorous analytical two-fluid treatment of drift waves driven solely by density inhomogeneities. Effects of the toroidal magnetic field configuration, the Landau resonance, a peaked diamagnetic frequency and a sheared rotation of the plasma have been taken into account. These effects either stabilise or destabilise the drift waves and to determine the net result on the drift waves requires careful analysis. To this end, dispersion relations have been obtained in various limits to determine when to expect the different effects to be dominant. The main result of this part is that with a large enough rotational shear, the drift waves will be quenched.</p><p>In the second part we focus on temperature effects and thus treat reactive drift waves, specifically ion temperature gradient and trapped electron modes. In fusion plasmas the α-particles, created as a by-product of the fusion process, transfer the better part of their energy to the electrons and hence the electron temperature is expected to exceed the ion temperature. In most experiments until today, the ion temperature is greater than the electron temperature and this have been proven to improve the plasma confinement. To predict the performance of future fusion plasmas, where the fusion process is ongoing, a comprehensive study of hot-electron plasmas and external heating effects have been carried out. Especially the stiffness (heat flux vs. inverse temperature length scale) of the plasma has been examined. This work was performed by simulations done with the JETTO code utilising the Weiland model. The outcome of these simulations shows that the plasma response to strong heating is very stiff and that the plasma energy confinement time seems to vary little in the hot-electron mode.</p>
149

Drift-Type Waves in Rotating Tokamak Plasma

Asp, Elina January 2003 (has links)
The concept of energy production through the fusion of two light nuclei has been studied since the 1950’s. One of the major problems that fusion scientists have encountered is the confinement of the hot ionised gas, i.e. the plasma, in which the fusion process takes place. The most common way to contain the plasma is by using at magnetic field configuration, in which the plasma takes a doughnut-like shape. Experimental devices of this kind are referred to as tokamaks. For the fusion process to proceed at an adequate rate, the temperature of the plasma must exceed 100,000,000C. Such a high temperature forces the plasma out of thermodynamical equilibrium which plasma tries to regain by exciting a number of turbulent processes. After successfully quenching the lager scale magnetohydrodynamic turbulence that may instantly disrupt the plasma, a smaller scale turbulence revealed itself. As this smaller scale turbulence behaved contrary to the common theory at the time, it was referred to as anomalous. This kind of turbulence does not directly threaten existents of the plasma, but it allows for a leakage of heat and particles which inhibits the fusion reactions. It is thus essential to understand the origin of anomalous turbulence, the transport it generates and most importantly, how to reduce it. Today it is believed that anomalous transport is due to drift-type waves driven by temperature and density inhomogeneities and the theoretical treatment of these waves is the topic of this thesis. The first part of the thesis contains a rigorous analytical two-fluid treatment of drift waves driven solely by density inhomogeneities. Effects of the toroidal magnetic field configuration, the Landau resonance, a peaked diamagnetic frequency and a sheared rotation of the plasma have been taken into account. These effects either stabilise or destabilise the drift waves and to determine the net result on the drift waves requires careful analysis. To this end, dispersion relations have been obtained in various limits to determine when to expect the different effects to be dominant. The main result of this part is that with a large enough rotational shear, the drift waves will be quenched. In the second part we focus on temperature effects and thus treat reactive drift waves, specifically ion temperature gradient and trapped electron modes. In fusion plasmas the α-particles, created as a by-product of the fusion process, transfer the better part of their energy to the electrons and hence the electron temperature is expected to exceed the ion temperature. In most experiments until today, the ion temperature is greater than the electron temperature and this have been proven to improve the plasma confinement. To predict the performance of future fusion plasmas, where the fusion process is ongoing, a comprehensive study of hot-electron plasmas and external heating effects have been carried out. Especially the stiffness (heat flux vs. inverse temperature length scale) of the plasma has been examined. This work was performed by simulations done with the JETTO code utilising the Weiland model. The outcome of these simulations shows that the plasma response to strong heating is very stiff and that the plasma energy confinement time seems to vary little in the hot-electron mode.
150

Reaktive Toxizität in vitro

Laqua, Anja 07 February 2014 (has links) (PDF)
Es wird eine Bioassay-Analyse von 168 Testsubstanzen gegenüber Tetrahymena pyriformis beschrieben. Mithilfe dieses In-vitro-Ansatzes konnte eine erste prognostische Aussage über die toxische Wirkung unbekannter Stoffe getroffen werden. Aus den Konzentrations-Wirkungs-Beziehungen erfolgte eine Bestimmung der Toxizitätserhöhung gegenüber der Narkoselevel-Toxizität. Dadurch war eine mechanistische Interpretation der Wirkstärke der Fremdstoffe möglich. Die Wirkung der Fremdstoffe basiert auf direkten toxikologisch relevanten Reaktionsmechanismen mit nukleophilen Biomolekülen oder nach entsprechender enzymatischer Aktivierung und ermöglichte die Aufstellung von Strukturalarmen. Aus jeder Stoffklasse waren Vertreter direkt oder nach enzymatischer Biotransformation erhöht toxisch. Somit ist mithilfe der Ciliaten eine Vorhersage der direkten reaktiven Toxizität möglich. Zudem enthält es für eine metabolische Aktivierung bedeutsame Enzymsysteme. Damit ist es für eine prognostische Vorhersage der Toxizität unbekannter Stoffe anwendbar.

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