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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.
21

Entwicklung eines neuronalen Netzwerks als Basis zur automatisierten Holzartenerkennung

Bernöcker, Anton, Leiter, Nina, Wohlschläger, Maximilian, Versen, Martin 27 January 2022 (has links)
Holz ist ein vielseitig einsetzbarer nachwachsender Rohstoff. Neben seinem wirtschaftlichen Nutzen ist er für den Erhalt des Klimas unersetzlich. Eine sortenreine Sortierung für die Weiterverarbeitung von Altholz spielt für einen ressourcenschonenden Umgang eine wichtige Rolle. Um das Potenzial eines neuronalen Netzwerks basierend auf Messdaten der bildgebenden Fluoreszenzabklingzeitmessung für die Altholzsortierung aufzuzeigen, wurden zwei unterschiedliche Klassifikationsansätze auf Basis der Programmiersprache Python gewählt. Die Ergebnisse zeigen, dass die bildbasierte Klassifizierung der Holzart mit einer Genauigkeit von 47,36 % noch ausbaufähig ist. Eine datenbasierte Klassifizierung der Holzart mit einer Identifikationsgenauigkeit von 98,28 % ist dagegen vielversprechend.
22

フロリゲン複合体形成を制御するタンパク質キナーゼの解析と同定

川本, 望 25 May 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第19203号 / 生博第336号 / 新制||生||45(附属図書館) / 32195 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 荒木 崇, 教授 河内 孝之, 教授 佐藤 文彦 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM
23

CAD-Centric Dynamic Workflow Generation

Kenworthy, Travis L. 20 April 2009 (has links) (PDF)
CAD systems are important design tools that enable the designer to conceptualize, visualize, analyze, and manufacture a design (Shahin 2008). Although high-end CAD systems provide several built-in design applications, the users of CAD often select various custom or proprietary non-CAD analyses that constrain, optimize, or evaluate their designs. An efficient method is needed to perform trade studies from within the CAD environment. Methods have been developed to meet the challenges associated with this need. The methods have been implemented in a program, called the Process Integrator, which resides in a CAD system and allows the user to perform trade studies on an assembly model from within the CAD environment. The Process Integrator allows the user to create a generic process configuration to link analyses with CAD assemblies for optimization. The generic configuration can then be run at any time, on any assembly that meets the configuration requirements. Test cases are presented in which the efficiency of the automated process is demonstrated. Results indicate that significant time savings can be achieved through the application of these methods.
24

QUANTIFYING BRAIN WHITE MATTER STRUCTURAL CHANGES IN NORMAL AGING USING FRACTAL DIMENSION

Zhang, Luduan January 2006 (has links)
No description available.
25

Power amplifier design for 5G applications in 28nm FD-SOI technology / Développement d’un amplificateur de puissance pour des applications 5G en technologie 28nm FD-SOI

Torres, Florent 18 May 2018 (has links)
Le futur réseau mobile 5G est prévu pour être déployé à partir de 2020, dans un contexte d’évolution exponentielle du marché de la téléphonie mobile et du volume de données échangées. La 5G servira de levier à des applications révolutionnaires qui permettront l’émergence du monde connecté. Dans ce but, plusieurs spécifications pour le réseau sont attendues même si aucun standard n’est encore défini et notamment une faible latence, une consommation d’énergie réduite et un haut débit de données. Les bandes de fréquences traditionnellement utilisées dans les réseaux mobiles ne permettront pas d’atteindre les performances visées et plusieurs bandes de fréquences millimétriques sont à l’étude pour créer un spectre complémentaire. Cependant, ces bandes de fréquence millimétriques souffrent d’une forte atténuation dans l’air et dans les matériaux de construction. Plusieurs techniques vont être implémentées pour outrepasser ces limitations dans les zones urbaines denses comme le backhauling, FD-MIMO et beamforming phased array. Ces techniques entraînent l’utilisation d’un grand nombre de transmetteurs dans les stations de bases et dans les dispositifs de l’utilisateur final. La technologie CMOS offre d’indéniables avantages pour ce marché de masse tandis que la technologie FD-SOI offre des performances et fonctionnalités additionnelles. L’amplificateur de puissance est le bloc le plus critique à concevoir dans un transmetteur et consomme le plus d’énergie. Afin d’adresser les challenges de la 5G, plusieurs spécifications concernant la puissance consommée, la linéarité et le rendement sont attendues. Les variations de l’environnement dans les beamforming phased array et le contexte industriel nécessitent des topologies robustes alors qu’une reconfigurabilité au niveau de l’amplificateur de puissance est bénéfique dans le cas de circuits adaptatifs. Cette thèse adresse ces challenges en explorant la conception d’un amplificateur de puissance reconfigurable et robuste pour des applications 5G en intégrant des techniques de design spécifiques et en mettant en avant les avantages de la technologie 28nm FD-SOI pour la reconfigurabilité. / The 5G future mobile network is planned to be deployed from 2020, in a context of exponential mobile market and exchanged data volume evolution. The 5G will leverage revolutionary applications for the advent of the connected world. For this purpose, several network specifications are expected notably low latency, reduced power consumption and high data-rates even if no standard is yet defined. The frequency bands traditionally used for mobile networks will not permit the needed performances and several mmW frequency bands are under study to create a complementary frequency spectrum. However, these mmW frequency bands suffer from large attenuation inbuilding material and in free-space. Therefore, several techniques will be implemented to tackle these limitations indense urban areas like backhauling, FD-MIMO and beamforming phased array. This is leading to a large number of transceivers for base stations and end-user devices. CMOS technology offers undeniable advantages for this mass market while FD-SOI technology offers additional features and performances. The power amplifier is the most critical block to design in a transceiver and is also the most power consuming. To address the 5G challenges, several specifications concerning power consumption, linearity and efficiency are expected. The environment variations inbeamforming phased array and the industrial context drive the need for robust topologies while power amplifier reconfigurability is benefic in a context of adaptive circuits. This thesis addresses these challenges by exploring the conception of a robust and reconfigurable power amplifier targeting 5G applications while integrating specific design techniques and taking advantage of 28nm FD-SOI CMOS technology features for reconfigurability purposes.
26

Conception de circuits intégrés radiofréquences reconfigurables en technologie FD-SOI pour application IoT / Design of tunable radiofrequency blocks in FD-SOI technology for IoT applications

Desèvedavy, Jennifer 08 October 2018 (has links)
La pénétration importante d’objets communicants dans notre vie quotidienne révèle des défis important quant à leur développement. Notamment l’explosion d'applications multimédia sans fil pour l'électronique grand public fait de la consommation électrique une métrique clef dans la conception des dispositifs portables multimodes sans fil. Les émetteurs-récepteurs conventionnels proposent des performances fixes et sont conçus pour respecter ces hautes performances dans toutes les conditions de communication sans fil. Cependant, la plupart du temps, le canal n'est pas dans le pire cas de communication et ces émetteurs-récepteurs sont donc surdimensionnés. En connaissant l’état du canal en temps réel, de tels dispositifs pourraient s'adapter aux besoins et réduire significativement leur consommation électrique. Le défi consiste à respecter la Qualité de Service , ou Quality of Service (QoS) en anglais, imposée par les différents standards de communication. Afin de rester compétitifs, les émetteurs-récepteurs adaptatifs doivent donc proposer une même QoS que ceux déjà disponibles sur le marché. Ainsi, ni la portée de communication ni le temps de réponse ne peuvent être dégradés.Basé sur ces exigences, cette thèse propose une technique d'adaptation pour la conception d'un récepteur reconfigurable qui fonctionne à la limite des performances nécessaires pour recevoir le signal utile. Ainsi, le récepteur proposé est toujours au minimum de consommation électrique tout en garantissant la bonne QoS. Ceci permet alors de multiplier la durée de vie de sa batterie par un facteur 5.Cette adaptabilité est démontrée ensuite côté circuit par la conception d'un LNA (Amplificateur Faible Bruit) dont les performances sont reconfigurables. En effet, en tant que premier élément de la chaîne de réception, le LNA limite le récepteur en termes de sensibilité. Ces travaux exploitent la technologie FD-SOI (Fully Depleted Silicon-On-Insulator) pour d’une part, réduire la consommation du LNA et d’autre part, ajouter de la reconfigurabilité à ce même circuit. / Communicating objects are inviting themselves into daily life leading to digitization of the physical world. This explosion of multimedia wireless applications for consumer electronics makes the power consumption a key metric in the design of multi-mode wireless portable devices. Conventional transceivers have fixed performances and are designed to meet high performances in all wireless link conditions. However, most of the time, the channel of communication is not at worst case and these transceivers are therefore over specified. Being aware of the channel link conditions would allow such devices to adapt themselves and to reduce significantly their power consumption. Therefore, the challenge is to propose a QoS (Quality of Service) in terms of communication range, response time as instance, equivalent to industrial modules with a reduced overall power consumption.To address this purpose, this thesis proposes a design strategy for the implementation of adaptive radio-frequency receiver (Rx) modules. Hence the Rx front end achieves the correct QoS for various scenarii of communications with a minimum of power consumption.As a proof of concept, the adaptive approach is demonstrated with the design of a tunable LNA (Low Noise Amplifier). As the first element of the receiver chain, the LNA limits the receiver in terms of sensitivity and is therefore a good candidate to perform reconfiguration. The body biasing of the FD-SOI (Fully Depleted Silicon-On-Insulator) technology is first exploited to reduce the power consumption of a circuit and then as an opportunity to perform circuit tunability.
27

Aplicação da técnica LOD em métodos no domínio do tempo e freqüência para modelagem de meios convencionais e metamateriais / Application of LOD technique in time and frequency domain methods for modelling conventional and metamaterial media

Nascimento, Valtemir Emerencio do 19 October 2007 (has links)
Este trabalho tem por objetivo o desenvolvimento de métodos numéricos eficientes, tanto no domínio do tempo quanto na freqüência, para a modelagem da propagação de ondas em estruturas que apresentem combinações de meios convencionais e/ou metamateriais, particularmente os metamateriais onde tanto a permissividade quanto a permeabilidade são simultaneamente negativos. Em alguns casos à simulação de tais estruturas representa um grande desafio em virtude da grande demanda computacional requerida. Uma forma eficiente de se contornar este problema é a utilização de técnicas de divisão de operador, com destaque para a técnica implícita das direções alternadas (ADI), já amplamente explorada nos domínios do tempo e da freqüência, e mais recentemente a técnica localmente unidimensional (LOD). A técnica LOD é utilizada com destaque neste trabalho, onde pela primeira vez esta foi empregada em um método de propagação de feixe de ângulo largo em diferenças finitas no domínio da freqüência, o qual foi denominado por LOD FD-BPM. O passo seguinte foi estender sua aplicação para o domínio do tempo, sendo a primeira abordagem empregada em um método de propagação de onda em diferenças finitas no domínio do tempo, denominado por LOD TD-WPM. Em seguida, a técnica LOD foi aplicada ao método FDTD resultando em um formalismo implícito, denominado LOD-FDTD, o qual apresenta uma maior eficiência computacional do que o tradicional ADI-FDTD. Estas abordagens apresentaram uma excelente eficiência computacional em virtude da possibilidade de utilização de passos de tempos maiores do que o permitido pela condição de estabilidade de Courant-Friedrich-Levy (CFL), além de serem incondicionalmente estáveis como conseqüência da aplicação do esquema de Crank-Nicolson (CN). A restrição do método LOD-FDTD, referente à sua precisão de apenas primeira ordem no tempo, foi contornada com o uso do esquema de divisão de operadores conhecido como Strang splitting (SS), resultando no método de segunda ordem no tempo LOD-FDTD-SS. Os métodos FDTD, ADI-FDTD, LOD-FDTD e LOD-FDTD-SS foram também implementados com base no modelo de Drude com perdas, possibilitando, assim, uma modelagem adequada de meios metamateriais. Outra contribuição importante deste trabalho foi à implementação da condição de contorno split PML no formalismo LOD-FDTD para a simulação de problemas eletromagnéticos abertos. / This work focuses on developing efficient numerical methods, both in time and frequency domains, for modeling wave propagation in structures that present conventional media and/or metamaterial media combinations, particularly the metamaterials where both permeability and permittivity are simultaneously negative. In some cases, the simulation of such structures represent a great challenge, due to the great computational requirements. An efficient way of solving this problem is the usage of operator splitting techniques, specifically the alternate direction implicit (ADI) technique, already explored both in time and frequency domains, and recently the locally one-dimensional (LOD) . This work dedicates special attention to the LOD technique, where, for the first time, this one was applied in a finite difference frequency domain wide-angle propagation method, which was denominated LOD FD-BPM. The next step was to extend its application to the time domain, the first approach was used in a finite difference time domain wave propagation method, denominated LOD TD-WPM. Next, the LOD technique was applied to the FDTD method, resulting in an implicit formalism, denominated LOD-FDTD, which presents a better computational efficiency than the traditional ADI-FDTD. These approaches present an excellent computational efficiency, due to the possibility of using greater time steps than those permitted by the Courant-Friedrich-Levy (CFL) stability condition, being unconditionally stable as a consequence of applying the Crank-Nicolson (CN) scheme as well. The LOD-FDTD method restriction, referring to its first order accuracy in time, was circumvented by using the operator division scheme known as Strang splitting (SS), resulting in a second order time method LOD-FDTD-SS. The FDTD, ADI-FDTD, LOD-FDTD and LOD-FDTD-SS methods were also implemented with a lossy Drude model, making, this way, possible an adequate metamaterial media modeling. Another important contribution of this work was the implementation of the split PML contour condition in the LOD-FDTD formalism for the simulation of open electromagnetic problems.
28

Método FD-BPM semivetorial de ângulo largo para a análise de estruturas tridimensionais utilizando a técnica ADI / not available

Nascimento, Valtemir Emerencio do 28 June 2002 (has links)
O projeto de dispositivos ópticos integrados é de fundamental importância no desenvolvimento de sistemas de comunicações ópticas. Por esse motivo, várias técnicas de modelamento para estes dispositivos tem surgido na literatura. Esta corrida em direção à sofisticação das ferramentas de modelamento decorre da evolução natural dos processos de fabricação, que tem permitido a construção de estruturas com geometrias bastante complexas. Dentre as várias técnicas utilizadas atualmente nas simulações de dispositivos fotônicos destaca-se o método da propagação do feixe (BPM). Este método apresenta como grande atrativo o fato de ser de fácil implementação e de apresentar baixa carga computacional. Inicialmente, a técnica BPM foi empregada utilizando a equação de onda escalar de Helmholtz. Esta abordagem é eficiente desde que a diferença entre os índices de refração dos materiais utilizados no guia de onda seja pequena e que a geometria da estrutura não apresente variações na direção de propagação. Entretanto, a luz é uma onda eletromagnética que possui propriedades intrinsecamente vetoriais. As propriedades vetoriais (efeitos de polarização) tornam-se importantes quando estruturas que apresentam elevado contraste de índices de refração precisam ser investigadas. Neste trabalho o fenômeno da polarização é avaliado através da utilização da equação de onda semivetorial de Helmholtz em três dimensões, a qual é desenvolvida em termos das componentes transversais de campo magnético (Formulação H). A solução da equação de onda semivetorial de Helmholtz é obtida pelo método BPM expandido em diferenças finitas (FD). Os aproximantes de Padé de ordem (1,0), equivalentes à propagação no limite paraxial, e de ordem (1,1), equivalentes à propagação em ângulo largo, são implementados e seus resultados discutidos ) A propagação do campo no FD-BPM tridimensional proposto aqui se dá através da utilização da técnica implícita das direções alternadas (ADI), a qual proporciona uma ótima estabilidade com baixo esforço computacional. A validação deste método é feita através da simulação de guias de onda tipo rib, avaliando parâmetros numéricos como: passo de propagação longitudinal, largura da gaussiana de excitação inicial, passo de discretização transversal, número de iterações e índice de referência. Adicionalmente, também é investigada uma fibra óptica com geometria tipo D. Estes resultados serão comparados com os resultados existentes na literatura para estas estruturas a fim de garantir a eficácia do método. / It is well known that finite difference beam propagation methods have been a valuable tool for the simulation of a large variety of optical waveguides structures such as: Mach-Zehnder, Y junctions, directional couplers, switches, etc. The increasing complexity of these structures, either in terms of geometry or material composition, requires more accurate modeling techniques. Among the several techniques available nowadays the beam propagation method (BPM) is maybe the most celebrated one. This method has attracted a great deal of attention by virtue of its ease of implementation and low computational effort. Initially, the BPM was applied to solve the scalar Helmholtz equation. This approach can be quite efficient for waveguides exhibiting low refractive index contrast and no variation along the longitudinal direction. Light, by its turn, is an electromagnetic wave with intrinsically vectorial properties. The vectorial properties (polarization effects) become very important when high contrast and longitudinally varying structures are involved. In this work the polarization phenomenon is evaluated by means of the three-dimensional semivectorial Helmholtz equation, which is solved in terms of its transverse magnetic field components (H formulation). The solution of this semivectorial equation is obtained via the finite difference BPM method expanded in terms of the following Padé approximants: Padé(1,0), equivalent to the semivectorial equation in the paraxial limit, and Padé (1,1), the wide angle solution. The field propagation dynamics in both cases is performed via alternate direction implicit method (ADI), which provides good numerical stability and low computational effort. As far as the authors know, this is the first time that a wide-angle formalism based on Padé(1,1) and ADI technique is proposed to solve the semivectorial Helmholtz equation. The validation of this new wide-angle method is performed for three well known rib waveguides structures available in the literature, and its accuracy measured in terms of the following parameters: longitudinal step size, initial field (gaussian) width, transversal step size, iteration number, and reference refractive index. A D-shaped fiber is also investigated with this method for comparison purposes. The results obtained in all cases are checked against those available in the literature in order to guarantee the efficiency of the method.
29

Contribution à l'étude de transmetteurs aux fréquences millimétriques sur des technologies émergentes et avancées / Contribution to the study of transmitters at millimeter frequencies on emerging and advanced technologies

Hanna, Tony 21 December 2017 (has links)
Depuis près d'un demi-siècle, l'industrie de la microélectronique a prospéré grâce à la miniaturisation des transistors Si CMOS. Cependant, la course à la miniaturisation se heurtera dans les prochaines années à des barrières physiques incontournables. Ainsi, de nombreux travaux technologiques sont en cours de réalisation sur les technologies émergentes et avancées. Ces technologies, notamment le graphène et la CMOS FD-SOI, représentent de grandes opportunités dans le domaine de la microélectronique, et notamment pour la conception de circuits radiofréquences et millimétriques. En outre, avec l'évolution croissante des objets et services connectés, les chercheurs travaillent intensivement sur les systèmes sans fil de cinquième génération (5G). La demande de débit de donnés et le besoin de spectre ont motivé l'utilisation de fréquences millimétriques. Par conséquent, la recherche 5G est confrontée par un ensemble de défis. L'un des défis majeurs de la 5G est la réduction de la consommation d'énergie. En fait, l'efficacité énergétique est directement liée à la fiabilité et au coût des systèmes de communication. L'amplificateur de puissance est l’élément le plus consommateur d'énergie, et l'un des blocs les plus critiques des émetteurs-récepteurs radio. Ainsi, la recherche dans ce domaine est cruciale pour les systèmes de communication de la prochaine génération. Par conséquent, l'objectif de cette thèse est d'étudier et de concevoir des amplificateurs de puissance sur les technologies émergentes et avancées pour les applications 5G. / For nearly half a century, the microelectronics industry has flourished based on the scaling of the silicon CMOS transistor technology. However, the race to transistor miniaturization encounters inevitable physical barriers. Thus, many technological works are under way for the realization of future transistors on emerging and advanced technologies. These technologies, notably the graphene and the CMOS FD-SOI, represent great opportunities for research in the fields of microelectronics, and especially for the design of radiofrequency and millimeter circuits. Besides, with the rising evolution of wireless devices and services, researchers are intensively working on the fifth generation (5G) wireless systems. The demand for high speed data and the need for more spectrum, have motivated the use of millimeter wave carrier frequencies. Therefore, the 5G research is faced with an evolving set of challenges. One of the major challenges of the next generation communication technology is reducing energy consumption. In fact, the power efficiency is directly related to the reliability and cost of the communication systems. It is widely known that the radiofrequency power amplifier is the most power consuming component in the radio transceivers, and is also one of the most critical building blocks in radio front-end. Therefore, research in this area is crucial for next generation communication systems. Consequently, the objective of this thesis is to study and design power amplifiers on emerging and advanced technologies for 5G applications.
30

Diffusion and Conformational Dynamics of Semiflexible Macromolecules and Supramolecular Assemblies on Lipid Membranes

Herold, Christoph 11 December 2012 (has links) (PDF)
Understanding the interaction of polyelectrolytes with oppositely charged lipid membranes is an important issue of soft matter physics, which provides an insight into mechanisms of interactions between biological macromolecules and cell membranes. Despite the fact that many (bio)macromolecules and filamentous supramolecular assemblies show semiflexible behavior, prior to this work very little was known about the conformational dynamics and Brownian motion of semiflexible particles attached to freestanding lipid membranes. In order to address these issues, diffusion and conformational dynamics of semiflexible DNA molecules and filamentous fd-virus particles electrostatically adsorbed to cationic freestanding lipid membranes were studied on the single particle level by means of optical wide-field fluorescence microscopy. Supergiant unilamellar vesicles (SGUVs) with diameters larger than 100 m represent a perfect model of a freestanding membrane. In this work, a method was developed that enabled the reliable and efficient electroformation of cationic SGUVs on ITO-coated coverslips. The utilization of SGUVs as model freestanding lipid bilayers allowed for determination of the previously unknown surface viscosity of DOPC/DOTAP membranes. In particular, the analysis of the translational diffusion coefficients of small (10, 20, 50 nm) membrane-attached anionic polystyrene beads has shown that the surface viscosity of DOPC/DOTAP membranes with CDOTAP = 1–7 mol% is independent of the DOTAP concentration and equals η = (5.9 ± 0.2) × 10−10 Pa s m. The fluorescence video-microscopy investigation of single DNA molecules attached to cationic SGUVs revealed a previously unreported conformational transition of a membrane-bound DNA molecule from a 2D random coil, the original conformation in which DNA attaches to the membrane, to a compact globule. This membrane-mediated DNA condensation is favored at high cationic lipid concentrations in the membrane and long DNA contour lengths. The DNA compaction rate in the coil–globule transition is 124 ± 46 kbp/s, and the resulting DNA globule sizes were found to be 250–350 nm at DOPC membranes containing 1 mol% DOTAP and 130–200 nm for 7 mol% DOTAP, indicating a stronger compaction for higher charge densities in the membrane. Additional experiments with freestanding cationic membranes in the gel state and supported cationic lipid membranes with gel–fluid coexistence suggest that the DNA collapse on a freestanding fluid cationic membrane may be initiated by a local lipid segregation in the membrane and is accompanied by local membrane deformations, which eventually stabilize the compact DNA globule. Furthermore, in this work single molecule studies of random-coil DNA molecules and filamentous fd-virus particles on a freestanding cationic lipid bilayer with a low charge density were carried out. The experiments revealed that these particles can be described as semiflexible chains in 2D. Taken together, DNA molecules and fd-virus particles cover a broad range of the ratio of contour length and persistence length from 0.4 to 82. The results of this work demonstrate that the mobility of such membrane-attached semiflexible particles is strongly affected by hydrodynamics in the lipid membrane and the surrounding bulk fluid, and can in essence be described using a hydrodynamics-based theory for a disk-shaped solid membrane inclusion with a characteristic size approximately equal to the radii of gyration of the particles.

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