This thesis deals with the theoretical description of the qualitative characteristics and parameters of some modern active elements, also discusses the theory of signal flow graphs at the level applicable for the following frequency filter design methods. The thesis is also generally discussed the issue with the circuit simulator PSpice modeling theory and voltage amplifiers on the basic 6-levels. The practical part of the work is divided into two parts. The first practical part is dedicated to design four levels of simulation model of components LNVGA element. The second practical part contains detailed theoretical proposals for three circuit structures implementing the frequency filters 2nd order (based on the basic structure of the OTA-C) using signal flow graphs with configuration options of Q and fm based on the parameters of active elements in the peripheral structure and their verification with prepared LNVGA model layers.

En raison de leur impact sur la fiabilité des systèmes, les effets du rayonnement cosmique sur l’électronique ont été étudiés dès le début de l’exploration spatiale. Néanmoins, de récentes évolutions industrielles bouleversent les pratiques dans le domaine, les technologies standard devenant de plus en plus attrayantes pour réaliser des circuits durcis aux radiations. Du fait de leurs fréquences élevées, des nouvelles architectures de transistor et des temps de durcissement réduits, les puces fabriquées suivant les derniers procédés CMOS posent de nombreux défis. Ce travail s’attelle donc à la simulation des aléas logiques permanents (SEU) et transitoires (SET), en technologies FD-SOI et bulk Si avancées. La réponse radiative des transistors FD-SOI 28 nm est tout d’abord étudiée par le biais de simulations TCAD, amenant au développement de deux modèles innovants pour décrire les courants induits par particules ionisantes en FD-SOI. Le premier est principalement comportemental, tandis que le second capture des phénomènes complexes tels que l’amplification bipolaire parasite et la rétroaction du circuit, à partir des premiers principes de semi-conducteurs et en accord avec les simulations TCAD poussées.Ces modèles compacts sont alors couplés à une plateforme de simulation Monte Carlo du taux d’erreurs radiatives (SER) conduisant à une large validation sur des données expérimentales recueillies sous faisceau de particules. Enfin, des études par simulation prédictive sont présentées sur des cellules mémoire et portes logiques en FD-SOI 28 nm et bulk Si 65 nm, permettant d’approfondir la compréhension des mécanismes contribuant au SER en orbite des circuits intégrés modernes / The effects of cosmic radiation on electronics have been studied since the early days of space exploration, given the severe reliability constraints arising from harsh space environments. However, recent evolutions in the space industry landscape are changing radiation effects practices and methodologies, with mainstream technologies becoming increasingly attractive for radiation-hardened integrated circuits. Due to their high operating frequencies, new transistor architectures, and short rad-hard development times, chips manufactured in latest CMOS processes pose a variety of challenges, both from an experimental standpoint and for modeling perspectives. This work thus focuses on simulating single-event upsets and transients in advanced FD-SOI and bulk silicon processes.The soft-error response of 28 nm FD-SOI transistors is first investigated through TCAD simulations, allowing to develop two innovative models for radiation-induced currents in FD-SOI. One of them is mainly behavioral, while the other captures complex phenomena, such as parasitic bipolar amplification and circuit feedback effects, from first semiconductor principles and in agreement with detailed TCAD simulations.These compact models are then interfaced to a complete Monte Carlo Soft-Error Rate (SER) simulation platform, leading to extensive validation against experimental data collected on several test vehicles under accelerated particle beams. Finally, predictive simulation studies are presented on bit-cells, sequential and combinational logic gates in 28 nm FD-SOI and 65 nm bulk Si, providing insights into the mechanisms that contribute to the SER of modern integrated circuits in orbit

No description available.

Parmi les architectures candidates pour les générations sub-22nm figurent les transistors sur silicium sur isolant (SOI). A cette échelle, les composants doivent intégrer des films isolants enterrés (BOX) et des canaux de conduction (Body) ultra-minces. A ceci s'ajoute l'utilisation d'empilements de grille avancés (diélectriques à haute permittivité / métal de grille) et une ingénierie de la contrainte mécanique avec l'utilisation d'alliages SiGe pour le canal des transistors de type P. La mise au point d'une telle technologie demande qu'on soit capable d'extraire de façon non destructive et avec précision la qualité du transport électronique et des interfaces, ainsi que les valeurs des paramètres physiques (dimensions et dopages), qui sont obtenues effectivement en fin de fabrication. Des techniques d'extraction de paramètres ont été développées au cours du temps. L'objectif de cette thèse est de reconsidérer et de faire évoluer ces techniques pour les adapter aux épaisseurs extrêmement réduites des composants étudiés. Elle combine mesures approfondies et modélisation en support. Parmi les résultats originaux obtenus au cours de cette thèse, citons notamment l'adaptation de la méthode split CV complète qui permet désormais d'extraire les paramètres caractérisant l'ensemble de l'empilement SOI, depuis le substrat et son dopage jusqu'à la grille, ainsi qu'une analyse extrêmement détaillée du transport grâce à des mesures en régime de couplage grille arrière à température variable ou l'exploitation de la magnétorésistance de canal depuis le régime linéaire jusqu'en saturation. Le mémoire se termine par une analyse détaillée du bruit basse fréquence. / Silicon on insulator (SOI) transistors are among the best candidates for sub-22nm technology nodes. At this scale, the devices integrate extremely thin buried oxide layers (BOX) and body. They also integrate advanced high-k dielectric / metal gate stacks and strain engineering is used to improve transport properties with, for instance, the use of SiGe alloys in the channel of p-type MOS transistors. The optimization of such a technology requires precise and non-destructive experimental techniques able to provide information about the quality of electron transport and interface quality, as well as about the real values of physical parameters (dimensions and doping level) at the end of the process. Techniques for parameter extraction from electrical characteristics have been developed over time. The aim of this thesis work is to reconsider these methods and to further develop them to account for the extremely small dimensions used for sub-22nm SOI generations. The work is based on extended characterization and modelling in support. Among the original results obtained during this thesis, special notice should be put on the adaptation of the complete split CV method which is now able to extract the characteristic parameters for the entire stack, from the substrate and its doping level to the gate stack, as well as an extremely detailed analysis of electron transport based on low temperature characterization in back-gate electrostatic coupling conditions or the exploitation of channel magnetoresistance from the linear regime of operation to saturation. Finally, a detailed analysis of low-frequency noise closes this study.

Physiological signals, electroencephalogram (EEG) and heart rate variability (HRV), are generated by complex self-regulating systems. These signals are extremely inhomogeneous and nonstationary, and fluctuate in an irregular and highly complex manner. These fluctuations are due to underlying dynamics of the system. The synchronous neural activity measured as scalp EEG indicates underlying neural dynamics of the brain. Hence, quantitative EEG analysis has become a very useful tool in interpreting results from physiological experiments. The analysis of HRV provides valuable information to assess the autonomous nervous system (ANS). The HRV can be significantly affected by physiological state changes and many disease states. Hence, HRV analysis is becoming a major experimental and diagnostic tool. In this thesis, we focus on the study of EEG and HRV time series using tools from nonlinear time series analysis with special emphasis on its implications in detecting physiological state changes such as, in diseases like epileptic seizure and schizophrenia, and in altered states of consciousness as in sleep and meditation. The proposed nonlinear techniques are used in discriminating different physiological states from control states. Artifact processing of EEG signal Interferences (artifacts) from various sources unavoidably contaminate EEG recordings. In quantitative analysis, results can differ significantly by these artifacts, which may lead to wrong interpretation of the results. In this part of the thesis, we have devised methods to minimize ocular and muscle artifacts in EEG. The artifact correction methods are based on blind source separation (BSS) techniques such as singular value decomposition (SVD), algorithm for multiple signal extraction (AMUSE), canonical correlation analysis (CCA), information maximization (INFOMAX) independent component analysis (ICA) and joint approximate diagonalization of eigen-matrices (JADE) ICA. We have proposed a method to simulate clean and artifact corrupted EEG data based on the BSS methods. In order to enhance the performance of BSS methods, a technique called wavelet-filtered component inclusion method has been introduced. In addition, second-order statistics (SOS) and higher-order statistics (HOS) based BSS methods have been studied considering less number of EEG channels; and performance comparison of these methods has also been made. We have also addressed the problem of simultaneous correction of ocular and muscle artifacts in EEG recordings using the BSS methods. Irrespective of the BSS methods, the component elimination method has introduced high spectral error in all the bands after reconstruction of clean EEG. However, the wavelet filtered component inclusion method has retained almost all spectral powers of EEG channels in theta, alpha, and beta bands after ocular artifact minimization. When the number of EEG channels is very less, the enhanced CCA (SOS BSS) has given superior artifact minimization results than HOS BSS methods, especially in delta band. The component elimination method is used in muscle artifact minimization, and hence the SVD method cannot be used for this purpose since it leads to large spectral distortion of reconstructed EEG. The AMUSE and CCA methods have given comparable performance in muscle artifact minimization. In addition, the JADE method has introduced less mean spectral error compared to other methods. The CCA method has shown superior performance in simultaneous minimization of ocular and muscle artifacts, and AMUSE and JADE methods have given comparable results. Furthermore, the less computation time of wavelet enhanced SOS BSS methods make them very useful in real clinical environments. Fractal characterization of time series In biomedical signal analysis, fractal dimension (FD) is used as a quantitative measure to estimate complexity of physiological signals. Such analysis helps to study physiological processes of underlying systems. The FD can also be used to study dynamics of transitions between different states of systems like brain and ANS, in various physiological and pathological states. In this part, we have proposed a method to estimate FD of time series, called multiresolution box-counting (MRBC) method. A modification of this method resulted in multiresolution length (MRL) method. The estimation performance of the proposed methods is compared with that of Katz, Sevcik, and Higuchi methods, by simulating mathematically defined fractal signals, and also the computation time is compared between the methods. The MRBC and MRL methods have given comparable performance to that of Higuchi method, in estimating FD of waveforms, with the advantage of less computational time. In addition, various properties of the FD are studied and discussed in connection with classical signal processing concepts such as amplitude, frequency, sampling frequency, effect of noise, band width, correlation, etc. The FD value of signals has increased with number of harmonics, noise variance, band-width, and mid-band frequency, and decreased with degree of correlation in AR signal. An analogy between Katz FD and smoothed Teager energy operator has also been made. Application of fractal analysis to EEG and HRV time series The fluctuation of EEG potentials normally depends upon degree of alertness, and varies in amplitude and frequency. Hence, the EEG is an important clinical tool for studying sleep and sleep related disorders, epileptic seizures, schizophrenia, and meditation. In this part of the thesis, we have used FD which gives signal complexity, and detrended fluctuation analysis (DFA) which gives multiscale exponent of time series to quantify EEG. We have extended the concept of FD to multiscale FD to compute complexity of time series at multiple scales. The main applications of the proposed method are epileptic seizure detection, sleep stage detection, schizophrenia EEG analysis, and analysis of heart rate variability during meditation. For seizure detection, we have used intracranial EEG recordings with seizure-free and seizure intervals. In sleep EEG analysis, whole-night sleep EEG is used and results are compared with the manually scored hypnogram. The schizophrenia symptom is further categorized into positive and negative symptoms and complexity is estimated using FD and DFA. We have also analyzed HRV data of Chi and Kundalini meditation using FD and DFA techniques. In all the applications considered, we have tested for statistical significance of the computed parameters, between the case of interest and corresponding control cases, to discriminate between the physiological states. The ocular artifact has reduced FD while muscle artifact increased FD of EEG. The FD of seizure EEG has shown high value compared to that of seizure-free EEG. In addition, the seizure-free EEG has more DFA exponent-1 than seizure EEG. The value of FD of EEG is decreased with deepening of sleep, wake state having high FD value. The FD of REM state sleep EEG showed value between that of wake and state-1. The DFA exponent-1 has increased with deepening of sleep state, having small value for wake state. The REM state has given exponent-1 value between wake and state-1. The schizophrenia subjects have shown lower FD value than healthy controls in all the EEG channels except the bilateral temporal and occipital regions. The positive symptom sub-group has shown comparatively high FD values than healthy controls as well as overall schizophrenia sample in the bilateral tempero-parietal-occipital region. In addition, the positive symptom sub-group has shown significantly higher regional FD values than negative symptom sub-group especially in right temporal region. The overall schizophrenia samples as well as the positive and negative subgroup have shown least FD values in the bilateral frontal region. The values of DFA exponent-2 have shown significant high value in schizophrenia samples. In addition, the schizophrenia group has shown less DFA exponent-1 in bilateral temporal region than healthy control. The FD, multiscale FD, DFA exponents have shown significant performance in discriminating different physiological states from control states. The FD value of HRV time series during meditation is less compared to pre-meditation state in both Chi and Kundalini meditation. Irrespective of the type of meditation, meditation state has shown significantly high DFA exponent-1 than pre-meditation state, and significantly high DFA exponent-2 in pre-meditation state compared to meditation state. Functional connectivity analysis of brain during meditation In functionally related regions of the brain, even in those regions separated by substantial distances, the EEG fluctuations are synchronous, which is termed as functional connectivity. In this part, a novel application of functional connectivity analysis of brain using graph theoretic approach has been made on the EEG recorded from meditation practitioners. We have used 16 channel EEG data from subjects while performing Raja Yoga meditation. The pre-meditation condition is used as control state, against which meditation state is compared. For finding connectivity between EEG of various channels, we have computed pair-wise linear correlation and mutual information between the EEG channels, to form a connection matrix of size 16x16. Then, various graph parameters, such as average connection density, degree of nodes, characteristic path length, and cluster index, are computed from the connection matrix. The computed parameters are projected on to the scalp to get topographic head maps that give spatial variation of the parameter, and results are compared between meditation and pre-meditation states. The meditation state has shown low average connection density, less characteristic path length, and high average degree in fronto-central and central regions. Furthermore, high cluster index is shown in frontal and central regions than pre-meditation state. The parameters such as complexity, characteristic path length and average connection density are used as features in quadratic discriminant classifier to classify meditation and pre-meditation state, and have given good accuracy performance. Connectivity analysis using mutual information has given high average connection density in meditation state in theta, alpha and beta bands compared to pre-meditation state. The characteristic path length is high in delta, alpha and beta bands in meditation state. In addition, the meditation state has shown high degree and cluster index in theta and beta bands compared to pre-meditation state. Nonlinear dynamical characterization of HRV during meditation The cardiovascular system is influenced by internal dynamics as well as from various external factors, which makes the system more dynamic and nonlinear. In this part of the thesis, a novel application of using HRV data for studying Chi and Kundalini meditation has been made. The HRV time series are embedded into higher dimensional phase-space using Takens’ embedding theorem to reconstruct the attractor. After estimating the minimum embedding dimension to unfold the attractor dynamics, the complexity of the attractor is computed using correlation dimension, Lyapunov exponent, and nonlinearity scores. In all the analyses, the pre-meditation state is used as control state against which meditation state is compared. The statistical significance of the parameters estimated is tested to discriminate meditation state from control state. The HRV time series of both pre-meditation and meditation have shown similar minimum embedding dimensions in both Chi and Kundalini meditation. Irrespective of the type of meditation, the meditation state has shown high correlation dimension, largest Lyapunov exponent, and low nonlinearity score compared to pre-meditation state. Recurrent quantification analysis of HRV during meditation In this part, a novel application of recurrent quantification analysis (RQA) to HRV during meditation is studied. Here, the time series is embedded into a higher dimensional phase-space and Euclidean distance between the embedded vectors is calculated to form a distance matrix. The matrix is converted into binary matrix by applying a suitable threshold, and plotted as image to get recurrence plot. Various parameters are extracted from the recurrence plot such as percent recurrence rate, diagonal parameters (determinism, divergence, entropy, ratio), and vertical or horizontal parameters (laminarity, trapping time, maximal vertical line length). The procedure is applied to HRV data during meditation and pre-meditation (control) to discriminate between the states. The HRV of meditation state has shown more diagonal line structure whereas more black patches are observed in pre-meditation state. In addition, at low embedding dimensions, the meditation state has shown low recurrence rate, high determinism, low divergence, low entropy, high ratio, high laminarity, high trapping time, and less maximal vertical line length compared to pre-meditation state. These RQA parameters have shown superior performance in discriminating meditation state from control state.

The master thesis deals with designs of the single-ended and the fully-differential secondorder frequency filters with adjustable parameters. This filters operate in the current mode where main element is the current amplifier DACA (Digitally Adjustable Current Amplifier). The first part describes basic behaviour of frequency filters and distribution according to filter funcion, used parts and structure. The second part of thesis describes the design of the frequency filters by the M-C signal-flow graphs and the transformating single-ended structures to the fully-differential forms. The next part deals with properties of the active elements and their simulation models. The following part describe six circuits of the frequency filters with adjustable parameters and their simulations. Four simulation models with different properties were used for simulating of the DACA in the each circuits. The last part deals with the practical design and measurement of the selected frequency filters.

No description available.

The present work aims at a discursive analysis of testimonies of ex-political prisoners of the era of military dictatorship in Brazil, specifically the state of Sergipe, with the intention of exploring resistance brands. To compose the study analyzed in relation to Milton Coelho and Wellington Mangueira, since they were names of extreme representation of the fight against the military dictatorship in Sergipe, experiencing a terrible experience of the prison and torture. This study has the theoretical basis of French Speech Discourse Analysis (DA), starting from the postulates of Pêcheux (1988), Althusser (1980), Orlandi (1996, 2007, 2008, 2009) and Carvalho (2012) and the contributions of Other scholars, both from DA, and the history of Brazil and Sergipe, an example of Napolitano (2014) and Dantas (2004). We understand discourse as a social practice that has as its materiality a language and is influenced by history and ideology, producing effects of meaning. To carry out analyzes, we will use a qualitative methodology, apply theoretical categories of DA and use as corpus reports found on websites, blogs and documentaries. As a result, in the speeches of Milton Coelho and Wellington Mangueira it was possible to perceive a contradiction of what was presented by the military, of not practicing torture, and also a resistance of the ex-prisoners, which is the same of the persecutions and tortures did not surrender their Comrades and kept up the fight for ideals by publishing newspapers circulating inside the university, counting what was vetoed in the newspapers of external circulation, meetings in hiding places and small groups to demonstrate discontent with the system. As the Ideological Formations (IF) of the dominant and the dominated became evident through the regulation of the State Repressive Apparatus (SRA). Throughout the account as linguistic clues they reveal the combat to a system that used by numerous methods to stop a subversive action. Significant silence figures through discursive formations (FD) the manifestations of resistance during persecution and torture, making it clear that even so of coercion, they continue to mean; Since silence does not represent the annulment of the senses, since the subject always means through the symbolic. / O presente trabalho objetiva uma análise discursiva de depoimentos de ex-presos políticos da época da ditadura militar no Brasil, especificamente do estado de Sergipe, com o intuito de explorar marcas de resistência, decorrentes de políticas de censura no período citado. Para compor o estudo serão analisados os relatos de Milton Coelho e Wellington Mangueira, uma vez que foram nomes de extrema representação da luta contra a ditadura militar em Sergipe, vivenciando a terrível experiência da prisão e tortura. Tal estudo tem como fundamentação teórica a Análise de Discurso de linha francesa (AD), partindo dos postulados de Pêcheux (1988), Althusser (1980), Orlandi (1996, 2007, 2008, 2009) e Carvalho (2012) e das contribuições de outros estudiosos, tanto da AD, quanto da história do Brasil e de Sergipe, a exemplo de Napolitano (2014) e Dantas (2004). Entendemos o discurso como uma prática social que tem como materialidade a língua e sofre a influência da história e da ideologia produzindo, assim, efeitos de sentido. Para proceder às análises, utilizaremos a metodologia qualitativa, aplicaremos categorias teóricas da AD e utilizaremos como corpus relatos encontrados em sites, blogs e documentários. Como resultado, nos discursos de Milton Coelho e Wellington Mangueira foi possível perceber a contradição do que foi veiculado pelos militares, de não haver prática de tortura, e também a resistência dos ex-presos, que mesmo diante das perseguições e torturas não entregaram seus companheiros e mantiveram a luta pelos ideais, através da publicação de jornais que circulavam dentro da universidade, contando o que era vetado nos jornais de circulação externa, reuniões às escondidas e em grandes ou pequenos grupos para demonstrar o descontentamento com o sistema. As Formações Ideológicas (FI) do dominador e dos dominados ficaram evidentes por meio da regulação do Aparelho Repressivo de Estado (ARE). Em todo o relato as pistas linguísticas revelam o combate a um sistema que se utilizava de inúmeros métodos para deter a ação “subversiva”. O silêncio significante figura por meio das Formações Discursivas (FD) presentes nas manifestações de resistência durante as perseguições e torturas, deixando evidente que, mesmo diante da coerção, eles continuaram significando; uma vez que o silenciar-se não representa anulação dos sentidos, visto que o sujeito sempre significará por meio do simbólico.

Made available in DSpace on 2014-07-29T15:01:40Z (GMT). No. of bitstreams: 1 maria margareth goncalves.pdf: 3073051 bytes, checksum: a405b4aae069912b1212db181d1858f8 (MD5) Previous issue date: 2008-08-04 / Industrial activities are constantly producing wastes such as dyes which are usually found in the industrial effluents and constitutes a environmental problem due its toxicity and inadequate disposal. The use of fungi, in particular the white-rot fungus, have been found to be efficient for biodegrading these compounds. In addition, slow sand filtration have been reported to be the most efficient unit filtration processes to improve the physical, biological and chemical quality of potable water. The objective of this work was to investigate the removal efficiency of the dye FD&C azul Nº 2 Indigotina, by the use of the Trametes versicolor fungus combined with slow sand filtration. Two laboratory-scale filter columns of 0.08 m diameter and 0.90 m sand media depth were used to investigate the process performance. One slow sand filter, FLA, was applied in combination with the Trametes versicolor fungus, while the FLB was used as control. Three methodologies for the fungi growth were used. The results showed that the slow sand filtration is a prominent process for the removal of the dye FD&C azul nº 2 Indigotina when used in combination with the Trametes versicolor fungus. A maximum removal of 95% was found when the filter was inoculated with fungi grown on Petri dish. The average dye removal when the increased fungi biomass was inoculated to the filter was 70%. This result suggests that the filter performance increased when the fungus was inoculated with fungi grown on Petri dish. In addition, head loss was found to be higher in the FLA filter than in the FLA (control), indicating that the fungi biomass contributes to the head loss development. / Nas atividades industriais geradoras de resíduos os corantes são amplamente encontrados nos efluentes, quase sempre, constituindo um problema de ordem ambiental devido à sua toxicidade. O uso de fungos na degradação de corantes vem sendo estudado em diversos trabalhos científicos enquanto as vantagens econômicas e ambientais do uso de filtros lentos na produção de água bacteriologicamente segura há muito tempo já está descrita por diversos autores. Este trabalho teve por objetivo investigar a eficiência da remoção de corante artificial FD&C azul nº2 Indigotina, com uso do fungo de degradação branca Trametes versicolor em combinação com a filtração lenta. Para isso, foram instalados dois protótipos de filtros lentos denominados FL-A e FL-B em escala laboratorial, sendo que o filtro FL-A, foi inoculado com o fungo e o filtro FL-B, utilizado como controle, não foi inoculado com fungo. Três procedimentos foram empregados para o cultivo do fungo. Os resultados mostraram que a filtração lenta tem grande potencial para remoção eficiente de cor quando empregada em conjunto com o fungo Trametes versicolor. O melhor percentual de remoção do corante FD&C azul nº2 indigotina pelo fungo Trametes versicolor em combinação com a filtração lenta foi de 95% na metodologia com adição da biomassa de cultivo do fungo correspondente a duas placas de Petri. A média de descoramento da metodologia com adição de biomassa aumentada do fungo foi de 70%. Em todas as carreiras de filtração as perdas de cargas no FL-A, inoculado com fungo, foram superiores às do FL-B de controle. Este resultado indica que a biomassa gerada pelos fungos contribue para o aumento da perda de carga nos filtros lentos.

Les anévrysmes intracrâniens (AIC) sont des malformations artérielles développées au dépend des vaisseaux qui vascularisent le parenchyme cérébral. Leur rupture provoque une hémorragie intracrânienne, appelée hémorragie sous-arachnoïdienne, responsable d'une mortalité importante ou de séquelles fonctionnelles lourdes. Le traitement préventif de ces lésions est fréquemment réalisé lors d'une procédure endovasculaire (appelée coiling), par implantation, au sein de la poche artérielle pathologique, de spires métallique en platine à détachement contrôlé (les coils). La présence de ce matériel provoque une thrombose de la poche ce qui entraine secondairement une exclusion de l'anévrysme de la circulation artérielle. Une modalité de traitement endovasculaire plus récente fait appel à un dispositif implantable innovant appelé stent "flow diverter" (FD) que l'on déploie en regard de l'orifice qui fait communiquer l'artère et l’anévrysme : le collet anévrysmal. Ces stents FD, au design particulier, associant une faible porosité à une densité de pores élevée, agissent comme des "déflecteurs" et diminuent le flux sanguin entrant et sortant de l'anévrysme. L'objectif du traitement demeure toujours l'exclusion de l'anévrysme mais celle-ci est obtenue indirectement en agissant sur la "porte d'entrée" de l'anévrysme (le collet) et non plus directement sur la poche anévrysmale elle-même. Il ne s'agit plus alors de remplir le sac anévrysmal avec des coils mais de provoquer une thrombose stable et pérenne en altérant uniquement le flux sanguin qui le pénètre. Cette modalité thérapeutique novatrice a suscité un engouement important de la part des neuroradiologues interventionnels depuis 2007, date des premières implantations en Europe. Cependant, bien que reposant sur les capacités d'un tel dispositif à modifier le flux, on constate qu'il existe très peu d'outils d'imagerie disponibles actuellement et capables de quantifier ces modifications en un délai raisonnable pour pouvoir être exploité lors du traitement endovasculaire. De cette constatation clinique est né un projet collaboratif dont la finalité était le développement d'un outil logiciel basé sur les séquences d'angiographie numérisées soustraites et capable de mesurer au moins un des aspects du flux sanguin (et donc de ses modifications). La démarche de recherche mise en œuvre s'est effectuée en trois étapes. Premièrement, une étape expérimentale portant sur la réalisation d'un modèle "optimisé" d'AIC permettant le recueil de données hémodynamiques et d'imagerie. Puis, une étape de recherche plus fondamentale comprenant deux parties: d'une part des simulations numériques réalisées dans le cadre d'un modèle 3D réaliste d'AIC et d'autre part l'analyse d'images angiographiques. Au cours de cette étape, nous avons utilisé des outils de traitement d'images existants et développé certains algorithmes, puis les avons validés avant de les implémenter sous JAVA pour créer un outil logiciel d'analyse de flux. Enfin, la dernière étape du projet a consisté en l'exploitation du logiciel pour étudier une série clinique de patients traités d'un AIC par stent FD. Elle a permis de mettre en évidence certains facteurs prédictifs d'exclusion de l'anévrysme à long terme susceptible d'avoir un impact, en temps réel, sur le traitement des AIC par stent FD. / Intracranial aneurysms treatment based on intra aneurismal flow modification tend to replace traditionally coiling in many cases and not only complex aneurysms for which they were initially designed. Dedicated stents (low porosity, high pores density stents) called “flow diverter” stents are deployed across the neck of the aneurysm to achieve this purpose. The summation of three different mechanisms tend to lead to the healing of the aneurysm: immediate flow alteration due to the mechanical screen effect of the stent, physiological triggering of acute or progressive thrombus formation inside the aneurysm’s pouch and long term biological response leading in neointima formation and arterial wall remodeling. This underlying sequence of processes is also supposed to decrease the recanalization rate. Scientific data supporting the flow alteration theory are numerous and especially computational flow dynamics (CFD). These approaches are very helpful for improving biomechanical knowledge of the relations between blood flow and pathology, but they do not fit in real-time treatments. Neuroendovascular treatments are performed under dynamic x-ray modality (digital subtracted angiography a DSA-).However, in daily practice, FD stents are sized to the patient’s 3D vasculature anatomy and then deployed. The flow modification is then evaluated by the clinician in an intuitive manner: the decision to deploy or not another stent is based solely on a visual estimation. The lack of tools available in the angioroom for quantifying in real time the blood flow hemodynamics should be pointed out. It would make sense to take advantage of functional data contained in contrast bolus propagation and not only anatomical data. Thus, we proposed to create flow software based on angiographic analysis. This software was built using algorithms developed and validated on 2D-DSA sequences obtained in a swine intracranial aneurysm model. This intracranial animal model was also optimized to obtain 3D vascular imaging and experimental hemodynamic data that could be used to realize realistic computational flow dynamic. In a third step, the software tool was used to analyze flow modification from angiographic sequences acquired during unruptured IA from patients treated with a FD stent. Finally, correlation between flow change and aneurysm occlusion at long term follow-up with the objective of identifying predictive markers of long term occlusion was performed.