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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.
481

Contribution à l'intégration de centrales inertielles : outils d'aide à la conception et à l'optimisation

Arrijuria, Olivier 24 November 2008 (has links)
Le travail présenté dans ce mémoire concerne la réalisation d’un microsystème intégrant une centrale inertielle permettant la détection de mouvements. Le microsystème étudié est composé d’un accéléromètre capacitif associé à son électronique de traitement. L’accéléromètre capacitif a conduit à l’élaboration d’un outil logiciel afin de le pré-dimensionner. Ce pré-dimensionnement a été effectué en fonction des spécifications de l’application et de la technologie de fabrication. Cet outil intègre des modèles fluidiques et électrostatiques en vue de calculer des paramètres du modèle de l’accéléromètre pour une simulation système. L’électronique de traitement de l’accéléromètre capacitif a été conçue autour d’un convertisseur ”Sigma-Delta”. L’architecture ”Sigma-Delta” a nécessité des modifications pour pouvoir être adaptée au capteur. Nous avons alors développé, sous ”Matlab-Simulink”, une bibliothèque de composants permettant d’ajuster le fonctionnement du convertisseur. Une fois l’architecture optimisée et les caractéristiques des composants connues, la conception de l’architecture ”Sigma-Delta” est ainsi réalisable sous le logiciel CADENCE. / The aim of this thesis is the realisation of microsystem for movements detection. This microsystem is composed of capacitive accelerometers and of their electronics. The conception of capacitive accelerometers has induced developement of a software for the first dimensionnement of sensors. This software computes parameters of capacitive accelerometers thanks to electrostatic models, flow models, specifications of application and fabrication process. The electronics of capacitive accelerometer is a ”Sigma-Delta” convertor. The adaptation of convertor leads to developement of components libraries for ”Matlab-Simulink”. The simulation systems allows to fit parametres convertor for the application. After that,the conception of convertor under CADENCE software is then possible.
482

Mixed Simulations and Design of a Wideband Continuous-Time Bandpass Delta-Sigma Converter Dedicated to Software Dfined Radio Applications / Étude d'un émetteur numérique direct RF à base de synthétiseur numérique direct et de verrouillage par injection

Mariano, André Augusto 31 October 2008 (has links)
La chaîne de réception des téléphones mobiles de dernière génération utilisent au moins deux étages de transposition en fréquence avant d'effectuer la démodulation en quadrature. La transposition en fréquence augmente la complexité du système et engendre de nombreux problèmes tels que la limitation de l'échelle dynamique et l'introduction de bruit issu de l'oscillateur local. Il est alors nécessaire d'envisager une numérisation du signal le plus près possible de l'antenne. Cette dernière permet la conversion directe d'un signal analogique en un signal numérique à des fréquences intermédiaires. Elle simplifie ainsi la conception globale du système et limite les problèmes liés aux mélangeurs. Pour cela, des architectures moins conventionnelles doivent être développées, comme la conversion analogique-numérique utilisant la modulation Sigma-Delta à temps continu. La modélisation comportementale de ce convertisseur analogique-numérique, ainsi que la conception des principaux blocs ont donc été l'objet de cette thèse. L'application d'une méthodologie de conception avancée, permettant la simulation mixte des blocs fonctionnels à différents niveaux d'abstraction, a permis de valider aussi bien la conception des circuits que le système global de conversion. En utilisant une architecture à multiples boucles de retour avec un quantificateur multi-bit, le convertisseur Sigma-Delta passe bande à temps continu atteint un rapport signal sur bruit (SNR) d'environ 76 dB dans une large bande de 20MHz. / Wireless front-end receivers of last generation mobile devices operate at least two frequency translations before I/Q demodulation. Frequency translation increases the system complexity, introducing several problems associated with the mixers (dynamic range limitation, noise injection from the local oscillator, etc.). Herein, the position of the analog-to-digital interface in the receiver chain can play an important role. Moving the analog-to-digital converter (ADC) as near as possible to the antenna, permits to simplify the overall system design and to alleviate requirements associated with analog functions (filters, mixers). These currently requirements have led to a great effort in designing improved architectures as Continuous-Time Delta-Sigma ADCs. The behavioural modeling this converter, although the circuit design of the main blocks has been the subject of this thesis. The use of an advanced design methodology, allowing the mixed simulation at different levels of abstraction, allows to validate both the circuit design and the overall system conversion. Using a multi-feedback architecture associated with a multi-bit quantizer, the continuous-time Bandpass Delta-Sigma converter achieves a SNR of about 76 dB in a wide band of 20MHz.
483

Integrering av Lean-DMAIC för ett effektivare informationsflöde

Saarela, Markus, Bäckman, Mats January 2017 (has links)
Throughout history companies have come to realize the importance of work revolving quality in order to remain competitive on the market. Process development is a natural part of quality management. There exists several different philosophies and tools to make use of in this work, examples are Lean Production and Six Sigma. The state of research of the programs are well studied, but the combination of Lean and Six Sigma's work methodology DMAIC has many unknowns. The objective with this study has been to integrate Lean with DMAIC. The study's purpose has been to investigate whether DMAIC is consistent with theories about Lean. The question this study tried to answer is how Lean-DMAIC can be used to minimize inconsistencies in flow of information in a global production company. The purpose of this paper has mainly been answered with the aid of the literature study. The question at issue has mainly been answered by the case study. The objective has been answered with a combination of the case- and literature study. The work procedure is based on DMAIC´s methodology, while Lean provided the tools for success in combination with the philosophy´s train of thought that permeate the work. The results of the study illuminated that Lean-DMAIC works in a simultaneous fashion in order to find inconsistencies in existing flows of information; with these results the study's question has been answered. By the end of the study it was possible to ascertain that a better question for this particular study would have been how Six Sigma is consistent with Lean, as DMAIC is a method, thus they cannot be directly compared. In this study, DMAIC provided the step-for-step method for how to model the work and in what manner the process was examined. Lean on the other hand provided the right tools and the train of thought in order to succeed. This culminated in that several improvement measures could be produced based on the study's results. / Företag har under historiens gång kommit att förstå vikten av kvalitetsarbete för att vara konkurrenskraftiga på marknaden. Processutveckling är en naturlig del av kvalitetsarbete och det finns olika filosofier och verktyg tillgängliga för ändamålet, exempelvis Lean Production (Lean) och Sex Sigma. Forskningsläget av dessa program är välstuderade, men kunskapen om kombinationen av Lean och Sex Sigmas arbetsmetodologi Define-Measure-Analyze-Improve-Control (DMAIC) är lägre. Målet med undersökning är därför att integrera Lean med DMAIC och syftet är att utreda huruvida DMAIC är konsistent med teorier om Lean. Studiens frågeställning har varit hur Lean-DMAIC kan användas för att minimera avvikelser i informationsflöden i ett globalt produktionsföretag. Syftet uppnås med hjälp av en litteraturstudie, frågeställningen besvaras med hjälp av en fallstudie och målet med en kombination av studierna. Fallstudiens arbetssätt baseras på DMAIC som metodologi för arbetets struktur, medan Leans filosofi genomsyrar arbetet samtidigt som dess verktyg utnyttjas. Resultatet visade att Lean-DMAIC fungerar simultant, både teoretiskt och praktiskt, för att upptäcka avvikelser i informationsflöden. Därmed har undersökningens mål uppfyllts. Efter studien gick det att konstatera huruvida en bättre frågeställning hade varit hur Sex Sigma är konsistent med Lean, eftersom DMAIC är en metod framför filosofi. DMAIC gav steg-för-steg metoden för hur arbeten utformades och processen undersöktes, medan Lean gav verktyg och rätt tankesätt för att lyckas. Detta resulterade i förbättringsåtgärder åt företaget där fallstudien genomfördes.
484

Kvantovo-chemické štúdium nekovalentných interakcií / Quantum-chemical study of noncovalent interactions

Sedlák, Róbert January 2014 (has links)
The aim of this thesis is to investigate strength and origin of the stabilization for various types of noncovalent interactions. As this knowledge could lead to a deeper understand- ing and rationalization of the binding phenomena. Further, to participate on the de- velopment of new noncovalent data sets, which are nowadays inevitable in the process of parametrization and validation of new computational methods. In all the studies, different binding motifs of model complexes, which represent usually crystal structures, structures from unrelaxed scans or the local minima, were investi- gated. The calculations of the reference stabilization energies were carried out at ab initio level (e.g. CCSD(T)/CBS, QCISD(T)/CBS). Further, the accuracy of more ap- proximate methods (e.g. MP2.5, DFT-D or SQM methods) toward reference method, was tested. In order to obtain the nature of the stabilization the DFT-SAPT decompo- sition was frequently utilized. In the first part of the thesis, the importance and basic characteristics of different types of noncovalent interactions (e.g. halogen bond, hydrogen bond, π· · · π interaction etc.), are discussed. The second part provides the description of computational methods which were essential for our investigation. The third part of the thesis provides an overview for part...
485

Förbättringsmöjligheter i en testutrustning för transmissioner inom anläggningsmaskinsindustrin / Improvement possibilities in a test equipment fortransmissions in the construction machinery industry

Dåverklo, Josefin, Eriksson, Ebba January 2019 (has links)
All manufacturing requires some form of quality control to be able to ensure that a product will meet the customers requirements. Volvo Construction Equipment AB has a TDI station, Test Delivery Inspection, for transmissions. They experience a lack of insight and knowledge of the tests that has been done and therefore the purpose of this project is to investigate and improve Volvo CE's test equipment for transmissions and its reliability. The aim is to provide improvement proposals to the organization as well as a plan for the implementation, follow-up and control of the process. The study is an improvement project and therefore the methodology Six Sigma and parts of the work process DMAIC are used to accomplish the study. The method is adapted for improvement projects and is primarily used by larger producing companies. For data collection, both quantitative and qualitative methods are used. These methods are; the use of existing data from the organization, brainstorming and two different MSA tests aimed at examining the machine and the human's influence on the process. Several quality tools were helpful when analyzing the results and the two factors that has the biggest impact on the test equipment's results is the impact from the human and the test equipment itself such as the variation of the test equipment. An initial approach to reducing the impact of these factors and thereby making the test equipment more reliable is to make sure that all routines are followed and ensure that the method for extracting data from the test equipment is right. The conclusions are that the tolerance limits needs to be checked again just because they are based on personal experience and the process can be controlled with statistical process control. To follow up on the results, the same tests can be performed repeatedly and compared with this project. The project can be described as a standardized working method for similar improvement projects and can also be applied to other processes. / I all tillverkning krävs någon form av kvalitetskontroll för att kunna säkerställa att en produkt infriar kundernas krav. Volvo Construction Equipment AB har en TDI-station, Test Delivery Inspection, för färdigmonterade transmissioner och upplever en bristande insikt och kunskap om de tester som genomförs. Syftet med detta projekt är att undersöka och förbättra Volvo CE:s testutrustning för transmissioner och dess tillförlitlighet med målet att ge förbättringsförslag till organisationen samt en plan för genomförande, uppföljning och styrning av processen. Projektet är ett förbättringsprojekt och därför används metodiken Six Sigma och delar av arbetssättet DMAIC för att genomföra studien. Metoden är anpassad till förbättringsprojekt och används i första hand av större producerande företag. För datainsamlingen används både kvantitativa och kvalititativa metoder. Dessa metoder är; använding av befintlig data från organisationen, brainstorming samt två olika MSA-tester som syftade till att undersöka maskinens samt människans påverkan på processen. Ett flertal kvalitetsverktyg var till hjälp i analyserandet av resultatet. De två största påverkansfaktorerna på testutrustningens resultat är människan och maskinen. Ett första angreppssätt för att minska dessa faktorers påverkan och på så sätt göra testutrustningen mer tillförlitlig är att se till att alla rutiner följs samt att säkerställa metoden för att ta ut värden från testutrustningen. Processen kan styras med hjälp av statistisk processtyrning där resultatet även visar på att toleransgränserna bör ses över då de är satta utifrån erfarenhet. För att följa upp resultatet kan samma tester genomföras upprepade gånger och jämföras med detta projekt. Projektet kan berskrivas som ett standardiserat arbetssätt eller en metod för genomförande av liknande förbättringsprojekt och kan appliceras på andra processer.
486

Estudo do papel dos fatores sigma alternativos <font face=\"symbol\">sE e <font face=\"symbol\">sN  de Xylella fastidiosa. / Role of the alternative sigma factors <font face=\"symbol\">sE and <font face=\"symbol\">sN in Xylella fastidiosa.

Silva Neto, José Freire da 17 December 2007 (has links)
Linhagens mutantes foram obtidas para os fatores sigma <font face=\"symbol\">sE (RpoE) e <font face=\"symbol\">sN (RpoN) da bactéria Xylella fastidiosa. O mutante rpoE mostrou-se sensível a etanol e a choque térmico. Análises de microarranjo de DNA, de RT-PCR quantitativo e mapeamento de sítios de início de transcrição permitiram definir o regulon <font face=\"symbol\">sE em resposta ao choque térmico. Verificou-se co-transcrição entre os genes que codificam para <font face=\"symbol\">sE, seu anti-sigma e uma protease, e <font face=\"symbol\">sE não se mostrou auto-regulado, mas regulou o gene do anti-sigma. Análises similares às acima indicaram que o gene pilA, codificando a pilina da fímbria tipo IV, é positivamente regulado por <font face=\"symbol\">sN, enquanto o operon codificando proteínas da fímbria tipo I é regulado negativamente, explicando a maior formação de biofilme e auto-agregação no mutante rpoN. O perfil temporal de expressão da linhagem selvagem J1a12 em carência de nitrogênio foi determinado, além de genes induzidos por carência de nitrogênio via <font face=\"symbol\">sN. Assim, <font face=\"symbol\">sN regula genes de fímbrias e de resposta à carência de nitrogênio em Xylella fastidiosa. / Mutant strains were obtained for the sigma factors <font face=\"symbol\">sE (RpoE) and <font face=\"symbol\">sN (RpoN) in Xylella fastidiosa. The rpoE mutant showed to be sensitive to ethanol and heat shock. Microarray and quantitative RT-PCR analyses and determination of transcription start sites permitted to define the <font face=\"symbol\">sE regulon under heat shock. Co-transcription of the genes encoding <font face=\"symbol\">sE , its anti-sigma factor and a protease was observed, and <font face=\"symbol\">sE did not present auto-regulation, but it regulated the gene encoding the anti-sigma. Similar analyses indicated that the pilA gene, encoding the pilin of the type IV fimbriae, is positively regulated by <font face=\"symbol\">sN, while the operon encoding proteins of the type I fimbriae is negatively regulated, what explains the increased biofilm formation and auto-aggregation in the rpoN strain. Temporal expression profile of wild type strain J1a12 under nitrogen starvation was determined, as well as genes induced by nitrogen starvation via <font face=\"symbol\">sN. Thus, <font face=\"symbol\">sN regulates genes encoding fimbriae and genes for nitrogen starvation response in Xylella fastidiosa.
487

Estudo da precipitação de nitreto de cromo e fase sigma por simulação térmica da zona afetada pelo calor na soldagem multipasse de aços inoxidáveis duplex. / Chromium nitride and sigma phase precipitation study by heat-affected zone thermal simulation of duplex stainless steels multipass welding.

Ramirez Londoño, Antonio José 19 August 1997 (has links)
Os aços inoxidáveis duplex são materiais com um excelente desempenho, devido às suas sobressalentes propriedades mecânicas e excelente resistência à corrosão. Uma composição química adequada e microestrutura balanceada são as responsáveis por esta combinação de propriedades. No entanto, são estes mesmos fatores que os fazem especialmente susceptíveis à precipitação de fases intermetálicas, com efeitos maléficos no seu desempenho. Durante os ciclos térmicos de uma soldagem multipasse, a precipitação de intermetálicos é crítica. Foi desenvolvido um método para simular os ciclos térmicos de uma solda multipasse. Usando este método, foi estudada a precipitação de nitreto de cromo e fase sigma na zona afetada pelo calor submetida a temperaturas abaixo de 950°C dos aços inoxidáveis duplex UNS S31803 e S32550. Foram estudadas energias de soldagem na faixa de 0,4 a 1,0 kJ/mm. Foi determinada mediante extração de precipitados, seguida de difração de raios X na câmara de Debye-Scherrer e microscopia eletrônica de transmissão, a precipitação de nitreto de cromo para energias de soldagem de 0,4 a 1,0 kJ/mm e de fase sigma para energias de soldagem de 0,6-1,0 KJ/mm, no UNS S32550. Já o UNS S31803 não apresentou precipitação alguma para as energias de soldagem estudadas. Baseando-se nos resultados verifica-se que durante uma soldagem multipasse o UNS S31803 é menos propenso que o UNS S32550 à precipitação de intermetálicos na zona afetada pelo calor submetida a temperaturas abaixo de 950°C. / Duplex stainless steels belong to a group of high performance stainless steels regarding to corrosion and mechanical properties. These achievements are related to a suitable chemical composition and a balanced microstructure. During welding thermal cycles the microstructure changes and, consequently, corrosion and mechanical properties might be impaired due to a precipitation of intermetallic phases. This precipitation is an issue to be addressed for multipass welding. It was developed a method for simulate the multipass welding thermal cycles. Using this method chromium nitride and sigma phase precipitation was studied in a simulated heat affected zone of multipass welding (three passes) of UNS S31803 and UNS S32550 duplex stainless steels with different heat inputs (0,4 to 1,0 kJ/mm). The HAZ simulated region was below 950°C maximum temperature. Microstructural characterization of simulated samples showed discontinuous films of a precipitated phase at ferrite/ferrite grain boundaries and ferrite/austenite interfaces were observed only in a UNS S32550 duplex grade for all heat inputs simulated. This suggests that sigma phase and chromium nitride precipitation took place during sample thermocycling. X-ray diffraction in a Debye-Scherrer chamber of extracted precipitates and electron diffraction by TEM confirmed the presence of chromium nitrides for all range of heat input studied and sigma phase for heat input above 0,6 kJ/mm. On the other hand, microstructural analysis of UNS S31803 simulated samples did not present precipitation of intermetallic phases in the tested temperature range of HAZ. Based on these results, UNS S31803 is more resistant than UNS S32550 to intermetallic phases precipitation in multipass welding.
488

Proposta de melhoria para o processo DMAIC com integração do AHP: uma aplicação na operação de distribuição física de bebidas / Improvement proposal to the DMAIC process with integration of the AHP: an application in the beverage physical distribution operation

Farago, Randal 24 April 2015 (has links)
A competitividade de uma organização e, consequentemente, sua prosperidade perante concorridos mercados, depende muito da capacidade de inovação e aprimoramento de seus produtos/serviços e processos. A procura por melhores padrões de manufatura e serviços prestados aos clientes, além das aplicações de novas técnicas gerenciais, de melhoria contínua, de otimização e de tomada de decisão, têm atraído a atenção das organizações. O esforço criativo humano deve propor abordagens de caráter competitivo, combinando ferramentas e técnicas, conhecidas ou não, a fim de melhorarem seus desempenhos. Assim, o objetivo desta tese foi propor uma estrutura analítica integrando de forma sequencial o processo de melhoria contínua DMAIC e o método de análise multicriterial para tomada de decisão Analytic Hierarchy Process (AHP), com vistas às aplicações em operações de distribuição física de bebidas. Em um primeiro momento, por meio de uma pesquisa bibliográfica, foi proposta uma estrutura geral, denominada Estrutura Analítica DMAIC/AHP, envolvendo as teorias supracitadas. Além disso, com o auxílio de um estudo de caso, foi proposta uma estrutura detalhada para a tentativa de melhoria da operação de distribuição física de bebidas em uma empresa na cidade de Ribeirão Preto. O foco esteve também na oportunidade de se obter maior conhecimento do processo em estudo e melhorar o embasamento para a tomada de decisão. A aplicação da estrutura analítica foi dividida em três fases: fase 1 - definições para o projeto de melhoria; fase 2 - condução do processo de melhoria em si; e fase 3 (denominada metafase) - responsável por monitorar/acompanhar as atividades do projeto. A aplicação em um caso real permitiu a proposta de atividades e ferramentas para entendimento e aperfeiçoamento do processo; além de alternativas de decisão frente aos problemas encontrados; deu embasamento para a tomada de decisão no momento de se implementarem as melhorias e apresentou instrumentos para manutenção e controle das alterações propostas no projeto. Um ganho evidente com a junção das teorias foi que houve um auxílio mútuo entre elas. Dessa forma, o processo de melhoria contínua DMAIC, por meio de suas etapas minuciosas de conhecimentos de processos e de causas de problemas, pôde embasar de forma robusta a definição do modelo hierárquico do AHP, desde o objetivo geral a ser atingido, passando pelos critérios de decisão, até se chegar às alternativas de decisão propostas para o processo em estudo. Por outro lado, como o DMAIC não apresenta um método de tomada de decisão atraente, o AHP pôde auxiliar na tomada de decisão multicriterial de forma mais organizada, consistente e assertiva. / The competitiveness of an organization and consequently its prosperity before competitive markets, depends widely on the capacity for innovation and improvement of its products/services and processes. The pursuit for better manufacturing standards and services provided to customers, in addition to the applications of new management techniques, continuous improvement, optimization and decision-making, have attracted attention of organizations. The human creative effort should propose approaches of competitive basis, combining tools and techniques, known or not, in order to improve their performance. Thus, the objective of this thesis was to propose an analytical structure integrating sequentially the process of continuous improvement DMAIC of Six Sigma and the multi-criteria analysis method for decision making Analytic Hierarchy Process (AHP), in order to apply in real cases in beverage industries. At first, through a literature search, it was proposed a general structure, called Analytical Structure DMAIC/AHP, involving the above theories. In addition, with a case study aid, it was proposed a detailed structure attempting to improve the operation of physical distribution for beverages in a company in the city of Ribeirão Preto. The focus was also on the opportunity to gain greater knowledge of the process under study and improve the foundation for decision making. The application of analytical structure was divided into three phases: phase 1 - definitions for the improvement project; phase 2 - implementation of the improvement process itself; and phase 3 (called metaphase) - responsible for monitoring/following the activities of the project. The application in a real case allowed the proposal of activities and tools for the understanding and improvement of the process, as well as possibilities for more alternatives to problems encountered; provided foundation for decision making at the time of implementing the improvements and presented tools for maintenance and control of changes proposed in the project. An obvious gain from the junction of the theories was that there was a mutual aid between them. Thus, the process of continuous improvement DMAIC, through its detailed stages of knowledge of processes and causes of problems could robustly base the definition of the hierarchical model of AHP, since the overall objective to be attained, passing through the decision criteria, until they get to the alternatives of decisions proposed for the process under study. On the other hand, as the DMAIC does not present an attractive method of decision-making, AHP could assist in multi-criteria decision making more organized, consistent and assertive.
489

Caracterização do papel de dois fatores sigma de função extracitoplasmática da família FecI em Caulobacter crescentus. / Characterization of the role of two FecI-like extracytoplasmic function sigma factors in Caulobacter crescentus.

Balhesteros, Heloise 12 December 2014 (has links)
Fatores sigma de carência de ferro, representados por FecI de E. coli, direcionam a transcrição de genes de transporte de sideróforos (quelantes de ferro), e são geralmente regulados por fatores antissigma (FecR), que liberam o fator sigma após ligação do sideróforo no receptor de membrana externa (FecA). Caulobacter crescentus possui quatro genes para fatores sigma desta família. Ensaios de expressão gênica e crescimento indicaram que estes genes não respondem à disponibilidade de ferro. Em microarranjos de cDNA, apenas o gene fecA2 foi induzido em DfecR2 comparado à linhagem parental, sugerindo que este é o único gene alvo do fator sigma FecI2. Já DfecR4 mostrou indução em mais de 50 genes, alguns envolvidos na utilização de fontes alternativas de carbono. Ensaios fenotípicos com DfecI4 sugeriram que este gene é importante para o crescimento em g-ciclodextrina ou ácido caproico. Os resultados sugerem que o fator sigma FecI2 é bem específico, enquanto FecI4 parece regular uma resposta geral relacionada a compostos carbônicos, e não à homeostase de ferro. / Iron starvation sigma factors, whose prototype is E. coli FecI, direct transcription of genes involved in siderophore (iron chelators) transport, being usually regulated by anti-sigma factors (FecR), which release the sigma factor after siderophore binding to the outer membrane receptor (FecA). Caulobacter crescentus possesses four genes encoding FecI-like sigma factors. Gene expression and growth assays indicated that these genes do not respond to iron availability. In cDNA microarrays, only the fecA2 gene was induced in DfecR2 relative to the wild-type strain, suggesting that this is the only target gene of the FecI2 sigma factor. However, in DfecR4 there was induction of over 50 genes, some of them involved in utilization of alternative carbon sources. Phenotypic microarrays with the DfecI4 strain showed that this gene is important for growth in g-cyclodextrin or caproic acid. The results suggest that the FecI2 sigma factor is very specific, whereas FecI4 seems to regulate a more general response, related to carbon compounds rather than iron homeostasis.
490

Conditionnement de capteurs capacitifs dans des systèmes faible consommation / Capacitive sensors conditioning in low power systems

Kongpark, Patcharee 14 October 2016 (has links)
De nos jours, les capteurs capacitifs sont largement utilisés dans la mesure de grandeurs physiques telles que le déplacement, l’humidité, la pression, etc. Cette large diffusion est principalement due au développement des technologies MEMS qui ont permis de réduire leur coût, leur taille et leur consommation. Pour mesurer ces variations de capacité, des interfaces de conditionnement électronique ont été développées afin d’obtenir un signal électrique exploitable tel qu’une tension, un courant, un temps, une fréquence ou directement une sortie numérique. C’est dans ce cadre que se positionne l’objectif de cette thèse ; étudier la faisabilité d’une mesure capacitive à sortie numérique à partir d’un pont actif, une architecture développée et brevetée par l’équipe Conception et Test de Microsystèmes du LIRMM pour le conditionnement de capteurs résistifs basse consommation. La conversion numérique utilisée est une modulation Sigma-Delta 1 bit du 1er ordre, relativement facile à implémenter, et donc bien adaptée à l’intégration, à la faible consommation et à la réalisation d’interfaces génériques. Pour le retour 1 bit, deux structures de contre réaction ont été proposées : une contre-réaction résistive et une capacitive. Les résultats théoriques sont comparés à des résultats de simulations et à des mesures obtenues à partir des prototypes fabriqués en technologie CMOS 0,35μm d’Austria MicroSystem (AMS). / Nowadays, capacitive sensors are widely used in the measurement of physical quantities such as displacement, humidity, pressure, etc. This wide dissemination is mainly due to the development of MEMS technologies that have reduced their cost, size and consumption. To measure these capacitance changes, sensor electronic interfaces have been developed to obtain an exploitable electrical signal such as voltage, current, time, frequency or directly a digital output. It is in this framework that the aim of this thesis is positioned ; to study the feasibility of a capacitive measurement with digital output from an active bridge, an architecture developed and patented by the Design and Test Microsystems team of LIRMM for conditioning low power resistive sensors. The digital conversion used is a one-bit first-order Sigma-Delta modulation that is relatively easy to implement, and is well adapted to integration, low power consumption and realization of generic sensor interfaces. Two feedback architectures have been proposed: a resistive feedback and a capacitive. The theoretical results are compared with the results of simulations and measurements obtained from prototypes fabricated using a 0.35μm CMOS technology from Austria MicroSystem (AMS).

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