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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.
191

Caractérisation des oscillateurs spintroniques basés sur des couches magnétiques couplées / Characterization of spintronic oscillators based on coupled magnetic layers

Monteblanco Vinces, Elmer 09 July 2014 (has links)
Les nano-oscillateurs à transfert de spin (STNO) sont des candidats prometteurs pour la réalisation de composants radiofréquence (RF) intégrés, du à leur taille nanométrique, l'importante gamme de fréquences de base qu'ils peuvent couvrir, ainsi qu'à leur accordabilité autour de ces fréquences de base. Le signal RF est obtenu grâce à l'effet de transfert de spin (STT) qui donne lieu à une oscillation non-linéaire de l'aimantation dans un élément magnétorésistif. Jusqu'ici, ces excitations ont été examinées dans le cadre d'une couche magnétique isolée, c'est-à-dire sans prendre en compte le couplage entre couches. Cependant, nombreux aspects du spectre d'excitation ne peuvent pas être expliqués si l'on considère une couche isolée. Dans cette thèse nous nous attacherons à répondre à la question importante du couplage dynamique entre couches magnétiques dans un nanopilier magnétorésistif, afin de développer une meilleure compréhension des spectres d'excitation, et en particulier la dépendance en courant et champ magnétique appliqué des caractéristiques du pic d'émission, telles que la largeur de raie et la fréquence. Une première étude est réalisée pour un système composé de deux couches ferromagnétiques, couplées entre elles par le couplage RKKY (ce système est appelé un ferrimagnétique synthétique (SyF)). Le couplage induit des différences importantes dans la dépendance en courant de la fréquence par rapport aux excitations d'une couche isolée. Ces différences sont expliquées par l'important couplage dynamique RKKY. Une seconde étude prend en considération une interaction plus complexe, ayant lieu dans un nano-pilier STNO standard basé sur jonctions tunnel ou vannes de spin. Ce dispositif est composé d'un SyF ainsi que d'une couche libre(FL) magnétique, séparés par une fine couche métallique ou isolante. Pour ce système, en plus du couplage dynamique RKKY propre au SyF, nous prenons en compte le couplage dynamique généré par le champ dipolaire ainsi que le spin-torque mutuel (MSTT) entre la couche libre et le SyF. Ce couplage multiple donne lieu à deux signatures distinctes. La première est l'apparition d'un « saut » dans le spectre d'excitation dû à l'hybridation des modes SyF and FL dans le régime atténué. Le second est dû à l'interaction entre les excitations en régime entretenu, éventuellement via leurs composantes harmoniques, avec les excitations en régime atténué. Cette interaction donne lieu à des discontinuités dans la dépendance fréquence – champ, ce lorsque les excitations FL sont prédominantes. Il est intéressant de noter que cela mène à des régions ou la largeur de raie est diminuée. De plus, lorsque les excitations SyF sont prédominantes, la largeur de raie est diminuée par rapport aux cas ou les excitations FL sont prédominantes. Partant de ces observations, nous proposons une structure plus complexe, où un seconde couche de type SyF remplace la couche libre. Les résultats obtenus par une combinaison d'expériences, de simulations numériques et d'analyse analytique, montrent le rôle important des interactions dynamiques dans un nano-pilier. Ils ouvrent de nouvelles voies pour la conception de configurations STNO qui mèneront à des améliorations des performances du signal ainsi synthétisé. / Spin-torque nano-oscillators (STNOs) are promising candidates for integrated radiofrequency (RF) components due to their nanoscale size, the large range of base frequencies that can be covered, as well as the large achievable tuning ranges around the base frequency. The RF signal is obtained due to the spin transfer torque (STT) generating a non-linear magnetization oscillation in a magnetoresistive device. In the past, these excitations were investigated using the picture of a single (or independent) layer. However, many features of the excitation spectra observed experimentally in nanopillar devices cannot be explained considering a single layer. In this thesis we address the important question on the dynamical coupling between the magnetic layers inside a magneto-resistive nanopillar device, to gain a better understanding of the excitation spectra, i.e. the dependence of the frequency and the linewidth on current and applied magnetic field. A first study is realized for a coupled system, composed by two ferromagnetic layers, coupled by the interlayer RKKY coupling (so called Synthetic Ferrimagnet SyF). Due to the coupling the frequency dependence versus current is different as compared to excitations of a single layer. This is explained by the strong dynamical RKKY coupling. A second study considers a more complex interaction, occurring within standard STNO nanopillar spin valves or tunnel junctions. They are composed by a SyF separated by a metallic or insulating spacer respectively from the single free layer (FL). For this system we take into account besides the RKKY coupling within the SyF, also the dynamical dipolar field coupling and the mutual spin torque (MSTT) between the SyF and the free layer. We find two definite signatures arising from this coupling. The first is a gap in the steady state excitation spectra that is due to the hybridization of the SyF and FL modes in the damped regime. The second is the possibility of the spintorque driven excitation or its harmonics with the damped modes leading to discontinuities in the frequency field dependence when the free layer is dominantly excited. Interestingly this leads to a region of reduced linewidth. Furthermore for SyF layer dominated excitations, the linewidth is lower than in the FL dominated excitations. From these observations we propose a more complex structure, composed by two SyF layers where the single FL is replaced by a SyF. The results obtained by a combination of experiments, numerical simulations and analytical analysis, demonstrate the important role of the dynamic interactions in nanopillar STNOs and provide routes for designing novel STNO configurations that should lead to improved microwave performances.
192

Caracterização clássica e quântica de um oscilador paramétrico ótico bombeado em 780 nm / Classical and quantum characterization of an optical parametric oscillator pumped by 780 nm.

Túlio Brito Brasil 29 September 2015 (has links)
Nesta dissertação, descreveremos as primeiras medidas de ruído quântico em um oscilador paramétrico ótico (OPO) bombeado em 780 nm, construído no nosso laboratório. Esse OPO servirá de fonte de estados não clássicos da luz para interação com átomos de rubídio. Faremos uma revisão da teoria clássica do OPO: o bombeamento de um cristal não linear inserido dentro de uma cavidade ótica, produzindo dois feixes intensos de luz (sinal e complementar) com cores distintas. Calcularemos as expressões para o limiar de oscilação, potências de saída dos feixes convertidos e compararemos as principais diferenças entre OPOs com cristais do tipo I e tipo II. Analisaremos a descrição quântica do OPO, calcularemos os espectros de ruído para as quadraturas do bombeio refletido e para as quadraturas dos feixes gêmeos. Veremos que o OPO gera feixes com correlações quânticas, como o emaranhamento tripartido, entres os três feixes envolvidos no processo não linear. O cristal não linear utilizado no nosso experimento é um PPKTP tipo I. Ajustando a temperatura do cristal, podemos gerar feixes próximos da degenerescência até uma diferença de comprimentos de onda de aproximadamente 350 nm. A compressão de ruído quântico observado na diferença das amplitudes dos feixes sinal e complementar é 44%(-2.5 dB). O próximo passo é a implementação da técnica da rotação da elipse de ruído por cavidades óticas, para medir os ruídos de fase dos três campos . Fazendo a verificação do emaranhamento tripartido e determinando a sua dependência com o ruído de fônons inserido pelo cristal, a caracterização do OPO estará completa. A caracterização deste OPO é um passo importante nos objetivos do LMCAL, que é realizar a troca de informação entre luz e átomos em uma rede quântica. / In this dissertation, we will describe the first measurements of quantum noise in an optical parametric oscillator (OPO) pumped at 780 nm, built at our laboratory. This OPO will be the source of nonclassical states of light to interact with rubidium atoms. We will review the classical OPO theory: the pumping of a nonlinear crystal inside a cavity producing two bright light beams (signal and idler) with different colors. We will calculate the power threshold, output power of the converted beams and compare the main differences between type-I and type-II OPO.We will analyze the quantum description of the OPO, and calculate the noise spectrum of the reflected pump quadratures and for the twin beams quadratures. We will observe that the OPO generates beams with quantum correlations, for example, the tripartite entanglement among the three fields involved in the nonlinear phenomena. The nonlinear crystal used in our experiment is a PPKTP type-I. By adjusting the temperature of the crystal, we can generate beams from close to degenerate regime to a difference between them of 350 nm. The squeezing of quantum noise measured in the amplitude quadratures subtraction for signal and idler is 44%(-2.5 dB). The next step is to implement the method of ellipse noise rotation by an optical cavity, to be able to measure phase quadratures of the three different fields. By verifying the tripartite entanglement and determining the phonon noise due to the crystal, our source characterization will be complete. The characterization of this OPO is an important step in LMCAL goals, which is to realize exchange of information between light and atoms in a quantum network.
193

Construção de um oscilador paramétrico ótico para uma interface átomo-luz. / The building of an Optical Parametic Oscillator for light matter interface.

Rayssa Bruzaca de Andrade 06 September 2013 (has links)
Realizamos neste trabalho a construção de um Oscilador Paramétrico Ótico triplamente ressonante bombeado por um laser de Titânio Safira sintonizável na faixa entre 730 nm e 800 nm com potencial de extensão. Os feixes emitidos possuem comprimento de onda em torno de 1560 nm que estão na janela de transmissão das fibras óticas, com potência de saída máxima em torno de 420 mW e um limiar de oscilação mínimo de 53(3) mW quando bombeado por 780.126(0.03) nm. Para os feixes gêmeos a finesse da cavidade vale F=155 e as perdas intracavidade 0.05(0.1)%, permitindo, em tese, uma compressão de ruído próxima a 97(6)%. Esse OPO foi construído com o propósito de que o utilizemos como fonte geradora de estados triplamente emaranhados em um sistema de armazenamento e transferência de informação quântica quando em interação com um sistema atômico de rubídio. Medimos a potência de limiar e a eficiência de conversão para cada comprimento de onda do feixe de bombeio utilizado para caracterizar o sistema. / At the present work we conducted the construction of a triply resonant Optical Parametric Oscillator pumped by a Titanium-Sapphire laser, which is tunable between 730 nm to 800 nm. The emitted beams have wavelength around 1560 nm, in the optical fibers transmission window, maximum output of 420 mW and minimum oscillation threshold of 53(3) mW. For the twin beams, the cavity finesse is F=155 mW and the intracavity losses are 0.05(0.10)%, allowing, in principle, a noise compression close to 97(5)%. The present OPO was built having the purpose of being used as source of triply entangled states in a system for quantum information storage and transfer, while interacting with an atomic rubidium system. We measured the power threshold and conversion efficiency for each pump beam wavelength that we used to characterize the system.
194

Emaranhamento multicor para redes de informação quântica / Multicolor entanglement for quantum information network.

Antonio Sales Oliveira Coelho 19 April 2013 (has links)
Apresentamos nesta tese a primeira geração direta de emaranhamento tripartite entre feixes intensos de luz. Medimos o emaranhamento entre os feixes sinal, complementar e bombeio refletido, produzidos por um Oscilador Paramétrico Ótico (OPO) operando acima do limiar de oscilação. A principal característica do nosso sistema é a diferença entre os comprimentos de onda dos campos (l0 = 532.251 nm, l1 = 1062.102 nm, e l2 = 1066.915 nm). Esta é a primeira medida de emaranhamento entre mais de dois subsistemas produzidos por uma única fonte no âmbito de variáveis contínuas. Para investigar a existência emaranhamento, utilizamos o critério de positividade sob transposição parcial (PPT). Este critério, aplicado a sistemas compostos por estados gaussianos, dispostos em bipartições do tipo 1×(N 1), torna-se necessário e suficiente na demonstração do emaranhamento. Realizamos também a caracterização do emaranhamento produzido quando submetemos os campos a perdas, identificando regiões de parâmetros onde os estados apresentam emaranhamento frágil ou robusto. A fim de garantir que estamos lidando com estados gaussianos, investigamos a estatística das flutuações dos campos, mostrando excelente acordo entre os valores dos momentos de ordem mais alta da fotocorrente medida e os valores esperados para uma distribuição gaussiana. O estudo que apresentamos é um passo importante para a elaboração de uma rede de informação quântica que possibilitará a comunicação entre diferentes sistemas físicos. / We present in this thesis the first direct generation of tripartite entanglement among bright beams of light. We measured the entanglement among signal, idler and reflected pump beams, produced by an Optical Parametric Oscillator (OPO) operating above the threshold. The main feature of our system is the difference between the wavelengths of the fields (l0 = 532.251 nm, l1 = 1062.102 nm, e l2 = 1066.915 nm). This is the first measurement of entanglement among more than two subsystems produced by a single source, in a continuous variable system. In order to investigate the existence of entanglement, we applied the criterion of positivity under partial transposition (PPT). This criterion, applied to systems composed of Gaussian states, arranged in 1×(N1) bipartition, becomes necessary and sufficient to demonstrate entanglement. We also characterized the entanglement when the fields are submitted to losses, identifying regions of parameters where the states have fragile or robust entanglement. To ensure that we are dealing with Gaussian states, we investigate the statistics of the fields, showing excelent agreement among values of higher order moments of the photocurrent measured and expected values for a Gaussian distribution. The present study is an important step in the development of a quantum information network formed by different physical systems.
195

Properties of the light emitted by a silicon on-chip optical parametric oscillator (OPO). / Propriedades da luz emitida por um oscilador paramétrico ótico em chip de silício

Carlos Andres Gonzalez Arciniegas 22 September 2017 (has links)
The Optical Parametric Oscillator (OPO) has been one of the most versatile source of non-classical states of light. Usual configurations of such devices are a macroscopic second order nonlinear crystals inside an optical cavity. Recently the use of silicon photonics techniques allowed the implementation of high quality factor microcavities and OPOs which include several technological advantages over usual configuration as a small size, bigger bandwidth, CMOS compatibility, facility to engineer the dispersion properties and compatibility with commercial optical fiber communications. Nevertheless the nonlinearity present within these systems is a third order nonlinearity for which theoretical calculations lack in the literature. Here we describe theoretically the quantum properties of the light generated in an OPO with a third order nonlinearity. We showed that the effects of phase modulation (which are not present in the second order nonlinearity) and dispersion are determinant in the way that oscillation and entanglement is produced in the system. Despite of these effects, bipartite and tripartite entanglement is predicted with the use of the Schmidt modes formalism. We also describe the system when there are more modes exited within the cavity and a frequency comb is formed. In such a situation, using again the Schmidt modes formalism, multipartite entanglement was predicted as well. / O oscilador paramétrico ótico (OPO) tem sido uma fonte muito versátil de estados não clássicos da luz. A configuração usual destes OPOs consiste em um cristal macroscópico com não linearidade de segunda ordem no interior de uma cavidade ótica. Recentemente, devido ao desenvolvimento da fotonica de silício, foi possível a implementação de micro- cavidades óticas e OPOs que possuem varias vantagens sobre OPOs usuais. Não entanto a não linearidade destes sistemas é de terceira ordem. Neste trabalho, descrevemos teoricamente as propriedades quânticas da luz gerada num OPO com não linearidade de terceira ordem. Mostra-se que os efeitos de modulação de fase (não presentes na não linearidade de segunda ordem) e a dispersão são determinantes para a geração e o emaranhamento produzido no sistema. Emaranhamento bi e tri partito foi predito teoricamente usando o formalismo de modos de Schmidt. Também foi feita uma descrição quando mais modos da cavidade são excitados gerando um pente de frequência. Nesta situação. e utilizando novamente o formalismo de modos de Schmidt, foi predito emaranhamento multimodo destes sistemas.
196

Oscilador paramétrico óptico contínuo e unicamente ressonante no infravermelho próximo / Continuous optical parametric oscillator in the near infrared

Nery, Marina Trad, 1987- 21 August 2018 (has links)
Orientador: Flávio Caldas da Cruz / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-21T00:14:04Z (GMT). No. of bitstreams: 1 Nery_MarinaTrad_M.pdf: 8701569 bytes, checksum: 94cd9456a3956cb1553345343461b95e (MD5) Previous issue date: 2012 / Resumo: Esta tese reporta o projeto e a construção de um oscilador paramétrico óptico continuo de frequência unica e sintonizável em torno de 846 nm. 0 cristal responsável pela conversão de frequências e o MgO:PPSLT (Tantalato de Lftio periodicamente polado e dopado com 1% de Oxido de Magnésia), e este e bombeado por ate 6 W de um laser continuo emitindo em 532 nm. Um dos objetivos do experimento e a geração de segundo harmônica, a partir de luz infravermelha, resultando em radiação na região espectral do azul, mais ,precisamente em 423 nm, necessária para experimentos de aprisionamento e resfriamento de átomos neutros de Cálcio. Para isso foi montada uma cavidade em anel unicamente ressonante para o feixe sinal e foi observada oscilação do dispositivo em uma potencia limiar próxima de 5 W, mais alta do que o calculada previamente. Foi possível observar a emissão de 30 m W de radiação do feixe sinal o que representa uma potencia de 30 W dentro da cavidade, ja que o espelho de saída era 99,9% refletor. Também foi possível observar luz azul devido a geração de segundo harmônica (sem Casamento de fase) dentro do cristal PPSLT. Ao longo deste trabalho são apresentados cálculos detalhados da cavidade óptica, das curvas de sintonia do cristal por temperatura e periodicidade da grade e do ganho paramétrico óptico. Acreditamos que o alto limiar de oscilação do dispositivo esteja relacionado a perdas devidas ao efeito fotorrefrativo no cristal, produzido pelo laser de bombeio, já que as perdas da cavidade devido aos espelhos e ao cristal eram baixas. Esta hipótese deve ser melhor investigada em futuras implementação de OPOs bombeados por altas potencias na região espectral do visível / Abstract: This thesis reports the design and construction of an continuously tunable and single frequency optical parametric oscillator around 846 nm. The crystal responsible for the frequency conversion is MgO: PPSLT (periodically poled lithium tantalate doped 1% of magnesium oxide), pumped with up to 6 W by a continuous-wave laser emitting at 532 nm. One goal of the experiment is the second harmonic generation from infrared light, resulting in radiation in the blue spectral region, more precisely 423 nm, necessary for experiments of cooling and trapping of neutral calcium atoms. A ring cavity resonant only for the signal beam was mounted and oscillation has been observed with a threshold of 5 W, higher than previously calculated. It was observed 30 mW ofradiation from the signal representing an intracavity power of 30 W, given the output coupler reflectivity of 99.9% reflector. We also observed blue light due to second harmonic generation (without phase matching) within the crystal PPSLT. Throughout this work we present detailed calculations of the optical cavity, temperature tuning curves for the crystal period of the poling grate and the optical parametric gain. We believe that the observed high threshold is related to losses due to the photorefractive effect in the crystal produced by the pump laser, since other losses due to the cavity mirrors and the crystal were very low. This hypothesis should be further investigated in future implementations of OPOs pumped by high powers in the visible spectral region / Mestrado / Física / Mestra em Física
197

Dr. Syntlove eller, Hur jag slutade ängslas och lärde migfärga digitala syntar : En snåljåps guide till det dyra syntersizerljudet.

Hessle, Adam January 2017 (has links)
Uppsatsen presenterar en undersökning av skillnaden mellan analoga hårdvarusyntar och digitala mjukvarusyntar. Syftet är att färga de digitala mjukvarusyntarna så dessa efterliknar de analoga hårdvarusyntarna. Detta kan gynna situationer där man som Musik och Ljudproducent önskar efterlikna en analogsynt med digitala verktyg och medel. Tidigare forskning redogör hur signalerna från syntar upplevs. Efter mätningslabbar visade det sig att analoga hårdvarusyntar hade grövre vågformer, därav beslöt man sig för bitdjupsreducering som metod för att färga ljuden. Dock så visade sig bitdjupsreducering inte vara en tillräckligt färgande metod. Resultaten talade för att lyssnaren fortfarande kunde urskilja signalerna trots behandling.
198

Étude, conception optimisée et réalisation d’un prototype ASIC d’une extraction d’horloge haut débit pour une nouvelle génération de liaison à 80 Gbit/sec. / Analysis and design of an 80 Gbit/sec clock and data recovery prototype

Béraud-Sudreau, Quentin 12 February 2013 (has links)
La demande croissante de toujours plus de débit pour les télécommunications entraine une augmentation de la fréquence de fonctionnement des liaisons séries. Cette demande se retrouve aussi dans les systèmes embarqués du fait de l'augmentation des performances des composants et périphériques. Afin de s'assurer que le train de données est bien réceptionné, un circuit de restitution d'horloge et de données est placé avant tout traitement du coté du récepteur. Dans ce contexte, les activités de recherche présentées dans cette thèse se concentrent sur la conception d'une CDR (Clock and Data Recovery). Nous détaillerons le comparateur de phase qui joue un rôle critique dans un tel système. Cette thèse présente un comparateur de phase ayant comme avantage d'avoir une mode de fenêtrage et une fréquence de fonctionnement réduite. La topologie spéciale utilisée pour la CDR est décrite, et la théorie relative aux oscillateurs verrouillés en injection est expliquée. L'essentiel du travail de recherche s'est concentrée sur la conception et le layout d'une restitution d'horloge dans le domaine millimétrique, à 80 Gbps. Pour cela plusieurs prototypes ont été réalisés en technologie BiCMOS 130 nm de STMicrolectronics. / The increasing bandwidth demand for telecommunication leads to an important rise of serial link operating frequencies. This demand is also present in embedded systems with the growth of devices and peripherals performances. To ensure the data stream is well recovered, a clock and data recovery (CDR) circuit is placed before any logical blocks on the receiver side. The research activities presented in this thesis are related to the design of such a CDR. The phase detector plays a critical role in the CDR circuit and is specially studied. This thesis presents a phase comparator that provides an enhancement by introducing a windowed mode and reducing its operating frequency. The used CDR has a special topology, which is described, and the injection locked oscillator theory is explained. Most of the research of this study has focused on the design and layout of a 80 Gbps CDR. Several prototypes are realized in 130 nm SiGe process from STMicroelectronics.
199

Study and design of CMOS RF power circuits and modulation capabilities for communication applications / Étude et conception des circuits de puissance CMOS RF et nouvelles fonctionnalités de modulation pour des applications de communication

Madureira, Heider Marconi Guedes 15 June 2015 (has links)
Dans l’ère des systèmes de communication multi-standards, le besoin des circuits en radio fréquence (RF) flexibles et reconfigurables pousse l´industrie et le monde académique vers la recherche d´architectures alternatives d’émetteurs et de récepteurs RF. Dans cette thèse, nous nous intéressons aux émetteurs RF flexibles. Nous présentons une architecture basée sur l’utilisation d’un oscillateur de puissance composé d´un amplificateur de puissance dans une boucle de rétroaction positive. Pour des raisons de compatibilité avec des circuit numériques et dans le but de minimiser les coûts de fabrication, nous avons choisi la technologie CMOS. Ce choix génère des difficultés de conception des circuits en RF à cause des faibles tensions de claquage. Cette contrainte de conception a motivé le choix de la classe EF2 pour l’amplificateur de puissance afin de réduire le stress en tension sur les transistors. Nous présentons la conception de cet amplificateur de puissance de classe EF2, ainsi que la conception de l’oscillateur de puissance. Nous validons cette architecture avec une implémentation en technologie CMOS 0.13um de STMicroelectronics. Nous démontrons le bon comportement par une campagne de mesures des circuits fabriqués. Ce circuit répond aux contraintes de flexibilité de modulation et de puissance de sortie. Il peut donc être utilisé pour différents standards de communications. Les limitations inhérentes de cette architecture sont discutées et une modélisation mathématique est présentée. / This work presents the study, design and measurement of RF circuits aiming communication applications. The need for flexible and reconfigurable RF hardware leads to the need of alternative transmitter architectures. In the center of this innovative architecture, there is thepower oscillator. This circuit is composed of a power amplifier in a positive feedback loop soit oscillates. As the circuit under study is mainly composed of a power amplifier, a study on power amplifier is mandatory. Modern CMOS technologies impose difficulties in the efficient RF generation due to low breakdown voltages. In order to reduce the voltage stress on the transistors, wave form-engineering techniques are used leading to the use of class EF2. Thedesign and measurement of a class EF2 power amplifier and power oscillator are shown. Thecircuits were implemented in standard STMicroelectronics 0.13um CMOS. Correct behaviorfor the circuits was obtained in measurement, leading to a first implementation of class EF2 inRF frequencies. From a system perspective, the proposed architecture is shown to be flexible and able to generate different modulations without change in the hardware. Reconfigurability is shown not only in modulation but also in output power level. The limitations of this architecture are discussed and some mathematical modeling is presented.
200

Physico-Chemical and Microfluidic Approaches Toward Engineering Oscillating and Communicating Chemical Droplets / Approches physicochimiques et microfluidiques vers l'ingénierie oscillante et les gouttelettes chimiques communicantes

Torbensen, Kristian 28 September 2016 (has links)
La génération, propagation et la réception d’informations (bio/chimiques) entre les organismes individuels sont la clé de voûte de nombreux systèmes communicants intelligents et sont omniprésents dans la nature. Les colonies de lucioles synchronisent leurs flashs, et la contraction et l’expansion des muscles cardiaques sont quelques exemples parmi d’autres, où les signaux bio / chimiques générés par des sources synchronisées produisent un comportement coopératif. L’objectif final de cette thèse est de développer une plateforme fiable pour générer des réseaux de communication de liposomes, en encapsulant la réaction de Belousov-Zhabotinsky (BZ) en tant que source d’information ou un signal transmis, et d’étudier la dynamique d’un tel système. Pour atteindre cet objectif, plusieurs questions ont été abordées par une approche “bottom-up” et multi-échelle. Tout d’abord, nous avons étudié l’interaction entre des liposomes de DMPC dopés et non-dopés avec le cholestérol, l’acide myristique, tétradécylsulfate, tétradécylamine, et les espèces impliquées dans la reaction BZ en utilisant la diffusion de rayons X aux petits angles et par spectrophotométrie UV-visible. Des rangées 1D de micro-gouttelettes ont été fabriquées en encapsulant la réaction BZ en microgouttelettes au moyen de la microfluidique et la communication entre les gouttelettes adjacentes a été étudiée. Plus tard, nous avons démontré un système microfluidique facile à monter / démonter avec une conception robuste et une géométrie modulable pour générer des emulsions doubles d’eau dans l’huile dans l’eau (E/ H / O). Enfin, le comportement de ces doubles emulsions générées dans système microfluidique en utilisant des phosphoplipides comme tensioactif et du chloroforme comme phase huileuse, est rapporté. Nous avons montré, avec cette composition de la phase d’huile, que le comportement dynamique des émulsions doubles sous écoulement donne lieu à des phénomènes riches incluant la déformation et du “tip-streaming”. / Generation, propagation and reception of (bio/chemical) information between individual organisms are the keystone of many intelligent communicating systems, and are ubiquitous in Nature. Colonies of fireflies synchronize their flashes, and contraction and expansion of heart muscles are few examples among others, where bio/chemical signals generated by synchronized sources produce a cooperative behaviour. The final objective of this thesis is to develop a reliable platform for generating communicative networks of liposomes, encapsulating the Belousov-Zhabotinsky (BZ) reaction as source of information or transmitted signals, and to study the dynamics of such a system. To reach this goal, several issues were addressed by following bottom-up and multi-scale approaches. First we investigated the interaction between both bulk DMPC liposomes, and liposomes doped with cholesterol, myristic acid, tetradecylsulfate, tetradecylamine, and the species involved in the BZ-reaction by using small angle X-ray scattering (SAXS) and UV-visible spectrophotometry. Than 1D arrays of micro-droplets were fabricated by encapsulating the BZ reaction into microdroplets by means of microfluidics, and the communication between adjacent droplets was studied. Later, we demonstrated an easy to assemble/disassemble and robust design for a microfluidic device with adjustable geometry, for generating monodisperse water-in-oil-in-water (w/o/w) double emulsions. Finally, the behavior of w/o/w double emulsions generated in a microfluidic device, using phospholipids as surfactant and chloroform as the oil phase, was reported. We showed, with this composition of the oil phase, that the dynamic behaviour of the double emulsions under flow gave rise to different phenomena, such as deformation and tip-streaming.

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