Over the past few decades, surface dielectric barrier discharge (SDBD) actuators have been studied extensively as aerodynamic flow control devices. There has been extensive research on producing SDBD plasmas through excitation by sinusoidal high voltage in low-speed flows, resulting in local acceleration of the flow through the electrohydrodynamic (EHD) effect. However, high-speed flow control using SDBD actuators has not been considered to the same extent. Control through thermal perturbations appears more promising than using EHD effects. SDBDs driven by nanosecond repetitively pulsed (NRP) discharges (NRP SDBDs) can produce rapid localized heating and have been used to produce better flow reattachment in high-speed flows. While surface actuators based on NRP DBDs appear promising for high-speed flow control, the physics underlying the plasma/flow coupling are not well understood and the actuators have yet to be fully characterized or optimized. In particular, methods for tailoring the plasma characteristics by varying the actuator’s electrical or geometrical characteristics have not been thoroughly explored.<div>In the current work, NRP SDBD actuators for control of high-speed flows are developed and characterized. As discussed previously, it is believed that the mechanism for high-speed flow control by these plasmas is thermal perturbations from rapid localized heating. Therefore, the goal is to design actuators that produce well-defined filamentary discharges which provide controlled local heating. The electrical parameters (pulse duration, PRF, and polarity) and electrode geometries are varied and the optimal configurations for producing such plasma filaments over a range of ambient pressures are identified. In particular, single and double sawtooth shaped electrodes are investigated since the enhanced electric field at the electrode tips may permit easier production of “strong” (i.e. higher temperature) filaments with well-defined spacing, even at low pressure. Time-resolved measurements of the gas temperature in the plasma will be obtained using optical emission spectroscopy (OES) to assess the thermal perturbations produced by the actuators. To the author’s knowledge, these will be the first such measurements of temperature perturbations induced by NRP SDBDs. The plasma structure and temperature measurements will be correlated with schlieren visualization of the shock waves and localized flow field induced by the discharges. Finally, the optimized actuators will be integrated into a high-speed flat plate boundary layer and preliminary assessment of the effect of the plasma on the boundary layer will be conducted.<br></div>

Avec l'objectif d'améliorer le rendement des lampes à excimères (Excilampe) à décharge à barrière diélectrique (DBD), un convertisseur en mode de courant, qui permet un ajustement précis de la puissance électrique injectée dans ce type des lampes, à été conçu et mis en oeuvre. Ce convertisseur fournit à la lampe un courant de forme d'onde carrée contrôlé au moyen de trois paramètres: l'amplitude, la fréquence et le rapport cyclique, pour obtenir un contrôle total de l'énergie électrique transmise à l'excilampe DBD. La mise en oeuvre intègre un transformateur élévateur comme interface entre la lampe et un commutateur. Les expériences démontrent le principe de fonctionnement de ce convertisseur, y compris les mesures de puissance du rayonnement UV. Les degrés de liberté du convertisseur sont utilisées pour analyser le comportement de la lampe sous différentes combinaisons de ces trois paramètres, et sont utilisés pour déterminer le point de fonctionnement optimal de la lampe. Ensuite, un convertisseur à résonance du type onduleur série, est proposé pour alimenter la lampe avec une grande efficacité électrique. Afin de contrôler effectivement la puissance de la lampe, le mode de fonctionnement de ce convertisseur utilise le mode de conduction discontinue et la commutation douce (ZCS), avec lequel on obtient aussi de faibles émissions électromagnétiques et l'on réduit les pertes de commutation. Les relations mathématiques obtenus à partir de l'analyse du diagramme de phase, ont été validées par des simulations et avec des résultats expérimentaux. Enfin, différentes topologies d'alimentations pour DBD sont comparées analytiquement et expérimentalement pour évaluer objectivement les avantages de chaque approche. Une des perspectives de ce travail est l'application de l'alimentation en créneaux pour l'étude de la performance d'autres types de réacteurs et d'excilampes DBD. / With the aim to provide a scientific tool for the enhancement of the Dielectric Barrier Discharge (DBD) Excimer Lamps (Excilamp) performance, a current-mode converter that allows an accurate adjustment of the electrical power injected into one of those lamps, is designed and implemented. With the proposed converter, the current supplied to the lamp has a square shape, controlled by means of three parameters: amplitude, duty cycle and frequency, which provides full control of the lamp electrical power. Implementation is made considering a step-up transformer interfacing the high-voltage lamp with the converter. Experiments demonstrate the operating principle of this converter, including UV power measurements for a DBD XeCl Excilamp. The capabilities of the converter are used to analyze the lamp behavior under different combinations of these three parameters, illustrating its capabilities for finding the optimal operating point. Then a series-resonant inverter for the supply of DBD) excilamp is proposed. In order to effectively control the lamp power, the operating mode of this converter combines discontinuous current-mode and soft-commutation (ZCS), obtaining as well low electromagnetic emissions, and reduced switching losses. The mathematical relationships obtained from state plane analysis, are validated with simulations and experimental results. Finally, several topologies of DBDs power supplies are compared analytical and experimentally to elucidate the advantages of each approach. After this work, one of the perspectives is the application of the square-shape supply in the performance study of other types of DBD excilamps and DBD reactors.

Les plasmas froids dans l’air à pression atmosphérique ont trouvé de nombreuses applications ces dernières années. Grâce à une chimie très réactive, les plasmas froids offrent une solution prometteuse pour le traitement bio-médical. Dans ce contexte, deux dispositifs d’exposition au plasma sont présentés :• le premier dispositif permet de générer des DBD (Décharges à Barrière Diélectrique) sur une échelle de temps nanoseconde (ns-DBD). L’échantillon biologique joue le rôle d’une électrode. La décharge se développe dans l’intervalle d’air entre la surface du diélectrique et l’échantillon biologique.• le.second dispositif d’exposition permet de générer des DBD de surface sur une échelle de temps nanoseconde (ns-SDBD). La décharge se forme le long de la surface du diélectrique, à proximité de l’électrode active. Pendant l’exposition au plasma, l’échantillon est placé face à l’applicateur. Contrairement à l’applicateur DBD, la décharge n’est pas directement en contact avec la solution biologique.Les deux systèmes d’exposition au plasma sont conçus de façon similaire, leurs dimensions autorisent l’exposition d’un échantillon biologique placé dans une boite de Petri classique. La cible biologique est un ensemble de cellules cancéreuses placées dans une solution de culture. Le travail présenté est essentiellement expérimental. Il se concentre sur la caractérisation électrique des décharges. Le plasma est créé avec des impulsions haute tension (de 4 kV à 11 kV), sur des temps très courts (de 10 ns à 14 ns de largeur) et avec des temps de montée brefs (2,5 ns, en fonction du générateur utilisé). Dans la configuration ns-DBD, l’énergie déposée par le plasma par impulsion est de l’ordre du mJ. En configuration ns-SDBD, l’énergie déposée est calculée, elle est de l’ordre de quelques dizaines de μJ. Une étude préliminaire sur le traitement d’échantillons biologiques est réalisée dans la configuration ns-SDBD. La viabilité de cellules de glioblastome est présentée en fonction de l’énergie déposée dans le plasma par impulsion. Selon les résultats de cette première étude, le plasma ns-SDBD a un effet sur la viabilité des cellules exposées dans les conditions décrites. / Cold plasmas in atmospheric pressure air have been used in many different applications in the past few years. Because of its high chemical reactivity, cold plasma treatment appears to be a promising solution for biomedical applications. In this context the study and realization of nanosecond plasma exposure devices for biomedical applications are presented :• the first exposure device generates DBD (Dielectric Barrier Discharge) on a nanosecond time scale (ns-DBD). The biological sample acts as an electrode. The discharges develops in the air gap be- tween the dielectric layer and the biological sample.• The second exposure device generates surface DBD on a nanosecond time scale (ns- SDBD). The discharge develops along the dielectric layer surface close to an active electrode. During plasma exposure, the biological sample faces the discharge device. By contrast to the DBD configuration, the discharge is not in direct contact with the surface of the solution.Both exposure devices are designed in a same way,. the dimensions allow plasma treatment of biological sample contained in a standard Petri dish. The biological targets are cancer cells in a liquid culture medium. The work is mainly experimental. It focuses on the electrical characterization of discharges. The plasma is created using short (10-14 ns of FWHM) high-voltage (up to 4 or 11 kV) pulses of fast rise times (2-5 ns depending on the pulse generator). In the ns-DBD configuration the energy deposited into plasma per pulse is in the order of millijoule. In the ns-SDBD configuration, we calculated the energy deposited into plasma per pulse in a range of tens of μJ. A preliminary study on treatment of biological samples by ns-SDBD plasma is performed. The glioblastoma cells viability was presented as a function of the energy deposited into plasma per pulse. According to this preliminary result the ns-SDBD plasma has an influence on the viability of the cells in the given conditions.

Cette thèse se situe à l’interface entre la biologie et la biophysique. Les méthodologies utilisées recouvrent principalement la résonance magnétique nucléaire (RMN), la diffusion des rayons X aux petits angles (SAXS), le dichroïsme circulaire (CD) et la spectroscopie de fluorescence. Une première partie vise à étudier le domaine de liaison à l’ADN (DBD) du récepteur des androgènes (AR) et les déterminants de l’interaction avec l’ADN. Une mutation faux-sens dans le DBD altère la spécificité de reconnaissance de l’ADN du récepteur bien que la structure tridimensionnelle soit identique au DBD sauvage. Les résultats montrent un changement dans la dynamique du récepteur mutant entrainant une déstabilisation de l’homo-dimère.La seconde partie de ma thèse consiste à établir un lien séquence/fonction au niveau du domaine N terminal (NTD) de AR. D’après la littérature, cette région joue un rôle important pour l’activité du récepteur, et elle est également décrite comme étant intrinsèquement désordonnée. Les résultats révèlent que cette région établit des contacts transitoires avec le DBD. Ceci suggère l’existence d'un couplage allostérique entre le DBD et les résidus adjacents sur le NTD.Ce couplage modifie l'ensemble conformationnel accessible au NTD en favorisant une conformation en hélice-α. / My PhD project is at the boundary between biology and biophysic. Methods used include nuclear magnetic resonance (NMR), small ange X-ray scattering (SAXS), circular dichroïsm (CD) and fluorescence spectroscopy. The androgen receptor (AR) DNA binding domain (DBD) and its interaction with DNA was studied in a first part. A mutation in the DBD leads to a modified DNA recognition by the mutant compared to the wild-type. Our results indicate changes in dynamic of the mutant receptor that leads to the homodimer destabilisation.The second part of my project aim to establish a link between sequence and function of the AR N terminal domain (NTD).As described in literature, this region is involved in the activity of the receptor and is also an intrinsically disordered protein (IDP). The results obtained during my thesis indicate that this region is involved in transient contact with the DBD. This suggest an allosteric coupling between the DBD and the neighboring residues on the NTD.This coupling modifies the conformational ensemble accessible to the NTD by stabilizing a α-helix conformation.

Mechanotransduction is fundamental to many sensory processes, including balance, hearing and motor co-ordination. However, for such an essential feature, the mechanism(s) that underlie it are poorly understood. The mechanotransducing stretch receptors that relay information on the tonicity and length of skeletal muscles have been well-defined, particularly at the gross anatomical level, in a wide variety of species, encompassing both vertebrates and invertebrates. To date, there exists a wealth of data describing them, anatomically, as well as good electrophysiological data from stretch receptors of some larger organisms. However, comparatively few studies have succeeded in identifying putative mechanotransducing molecules in such systems. Nonetheless, this class of sensory mechanotransducers perhaps offer the best means of identifying molecules that permit the stretch-sensitivity of such endings, revealing new information about the underlying mechanisms of stretch receptors, and mechanoreceptors more generally. However, a different approach is clearly needed; a theoretical approach, utilising mathematical modelling, offers a powerful means of pooling the current wealth of knowledge on the reported electrophysiological behaviour of muscle stretch receptors. This study, therefore, develops an extended theoretical model of a stretch receptor system in order to reproduce, in silico, the reported behaviour of both vertebrate and invertebrate stretch receptors, within the same modelling environment, thus enabling the first quantitative framework for comparing these data, and moreover, making predictions of the likely roles of specific molecular entities within a stretch receptor system. Subsequently, this study utilises a model in vivo system to test these theoretical predictions. The genetic toolbox of D. melanogaster offers a wide range of tools that are extremely suitable for identifying mechanotransducing molecules in stretch receptors. However, very little is currently known about such endings in this organism. This study, therefore, firstly characterises a putative stretch receptor organ in larval Drosophila, the dbd neuron, via a novel experimental approach. It is shown that this neuron exhibits known properties of stretch receptors, as previously observed in other, similar organs. Furthermore, these observations bear out the predictions of the mathematical model. Having defined the dbd neuron as a muscle stretch receptor, pharmacological and genetic assays in this system, combined with predictions from the mathematical model, identify a key role for the recently-discovered DmPiezo protein as an amiloride-sensitive, mechanically-gated sodium channel (MNaC) in dbd neurons, with TRPA1 also acting in this system in a supporting role. These data confirm the essential role of an MNaC in mechanosensory systems, but also supply important evidence that, whilst the electrophysiological mechanisms in stretch receptors are remarkably similar across taxa, different species likely employ various molecular mechanisms to achieve this.

The Dielectric Barrier Discharge (DBD) plasma actuators have received a significant attention of many researchers in the last few decades. The main focus of these studies has been on the flow control areas such as turbulent boundary layer separation and turbulent skin friction reduction. Little attention has been paid on the effect of the DBD plasma actuators on the aerodynamic noise reduction. In this regard, the aim of the current work is to investigate the effect of the DBD plasma actuator driven at relatively low voltages on vortex-induced noise. The first part of the current work includes an extensive assessment of the effect of the DBD plasma actuator on the narrowband tonal noise radiated from a flat plate with blunt trailing edge and an airfoil (NACA 0012) with blunt and cut-in type serrated trailing edge. The measurements were carried out at Reynolds numbers between 0.75 x 10 to the power of 5 and 4 x 10 to the power of 5. It is found that the DBD plasma actuator effectiveness depends on the direction of the generated electric wind. For example, a high reduction in the narrowband tonal noise level is achieved when a direct streamwise electric wind is injected into the wake region. However, using a plasma actuator, which can induce streamwise vortices into the wake region, shows more superior noise reduction capability at lower voltages. Flow measurement results revealed that the mechanism responsible for the narrowband tonal noise reduction when the electric wind is directly injected into the wake is not due the momentum injection into the wake deficit. Rather, the streamwise jet isolates the two separated shear layers and prevents the interaction between them. On the other hand, it is found that the break-up of the spanwise coherence of the vortex shedding is responsible for the significant reduction in the tonal noise level when the spanwise actuation is used. The second part of the current work comprises the effect of the DBD plasma actuator on both the narrowband tonal noise and interaction broadband noise radiated from both single and tandem cylinder, respectively. The experiments were conducted at subcritical Reynolds number ReD = 1.1 x 10 to the power of 4. The actuators were positioned at different azimuthal angles 27° ≤ θj ≤ 153°. For the single cylinder case, the acoustic results show the DBD plasma actuator that is positioned at θj = 133° leads to a more reduction in the narrowband tonal noise level when compared to the other angles. It is found that the streamwise jet produced by the plasma actuators plays an important role in prevention of the interaction between the shear layers that separates from the cylinder. For the tandem cylinders case, the acoustic results show that the simultaneous actuation of both the upstream and the downstream cylinders leads to more reduction in both the narrowband tonal noise and the interaction broadband noise level compared with the case where only the upstream or the downstream cylinder is actuated. The mechanism responsible for this noise reduction is found to be mainly due to the streamwise jet induced by the upstream cylinder activation, which delays the vortex shedding formation and reduces the turbulence intensity in the near wake region. On the other hand, the plasma induced jet against the main-flow direction works as a virtual fluidic barrier which displaces the wake produced by the upstream cylinder away from the downstream cylinder.

Idag väntar många patienter på transplantation av ett eller flera organ. Med nuvarande lagstiftning identifieras inte alla potentiella organdonatorer och därför kan inte dessa organ tas tillvara. Regeringen har därför tillsatt en utredning om det kan bli aktuellt med organdonation efter hjärtdöd. Detta uttrycks internationellt som Donation after Cardiac Death (DCD). Denna studiens syfte var att beskriva intensivvårdssjuksköterskors uppfattningar, tankar och känslor, samt förbereddhet kring begreppet donation efter hjärtdöd. Sju intervjuer av intensivvårdssjuksköterskor på två sjukhus i västra Sverige genomfördes och data analyserades med kvalitativ innehållsanalys. Resultatet presenteras som fyra kategorier: Upplevda farhågor och potentiella konsekvenser av DCD, Mötet med anhöriga, Tankar och känslor kring organisatoriska svårigheter och Tankar och känslor kring etiska dilemman. Slutsatser var att de intervjuade intensivvårdssjuksköterskorna ställde sig positiva till DCD och tidigare forskning visar att det kan vara en källa till ökning av organtillgång förutsatt att det är organisatoriskt genomförbart. / Today there are many patients on the waiting list to receive one or more organ transplants. With the current Swedish legislation not all potential organ donors are identified and therefore these organs are omitted as potential transplants. The government is in the process of investigating the possibility to implement organ donation after cardiac death, i.e. DCD. The aim of the study was to describe ICU nurses’ understanding, thoughts and emotions, as well as their preparations regards to DCD. Seven ICU nurses at two hospitals in western Sweden were interviewed and data were processed through qualitative content analysis. The results are presented as four categories: Perceived fears and potential consequences regarding DCD, the meeting with relatives, Thoughts and emotions regarding organizational difficulties and Thoughts and emotions regarding ethical dilemmas. Conclusions derived from the findings in the interviews with ICU nurses were a fully positive perception of DCD and that DCD could mean an increase in the amount of available organ donors given that legalisation and organisation processes are clear and possible to carry out.

Made available in DSpace on 2014-06-11T19:25:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-08Bitstream added on 2014-06-13T20:14:00Z : No. of bitstreams: 1 santos_alr_me_guara.pdf: 967831 bytes, checksum: 8cbbf37b87afd6e4a7c7ecc3380f9ebf (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Materiais poliméricos têm sido amplamente utilizados em várias áreas tecnológicas e biomédicas, devido às suas excelentes propriedades mecânicas, térmicas e elétricas. No entanto, estes materiais têm baixa energia de superfície e, portanto, não aderem facilmente a outros materiais. Por isso, para muitas aplicações é necessário modificar a superfície do polímero, a fim de aumentar a sua energia de superfície. Tratamentos a plasma à pressão atmosférica têm sido muito utilizados para modificar as propriedades superficiais de polímeros comerciais, devido aos baixos custos do processo. Este trabalho apresenta os resultados do tratamento de tereftalato de polietileno (PET), poliuretano (PU) e de politetrafluoretileno (PTFE) em plasma de descargas com barreira dielétrica (DBD) em ar, nitrogênio e argônio, à pressão atmosférica. As superfícies tratadas foram caracterizadas por medidas de ângulo de contato, espectroscopia de fotoelétrons de raios-X (XPS) e microscopia de força atômica (AFM). A superfície polimérica, modificada nas DBD a pressão atmosférica, mostraram uma redução significativa no ângulo de contato da água, embora uma recuperação parcial da molhabilidade ocorresse nos primeiros dias após o tratamento. Todavia, a recuperação foi insuficiente para que as amostras tratadas recuperassem a sua molhabilidade original. Análises de XPS mostraram um aumento na concentração de oxigênio na superfície, devido à formação de grupos polares, tais como C-O e OC= O. Um pequeno aumento na concentração de nitrogênio também foi observada. Imagens de AFM mostraram um aumento da rugosidade de polímeros tratados, decorrentes da interação física entre as espécies geradas na descarga e a superfície do polímero. A superfície ativada e a elevada tensão superficial dos polímeros tratados devem levar a um aumento da aderência do polímero. / Polymeric materials have been widely used in various biomedical and technological applications, due to their excellent mechanical, thermal and electric properties. However, these materials have low surface energy, and thus not easily adhere to other materials. Therefore, for many applications it is necessary to modify the polymer surface in order to increase its surface energy. Plasma treatments at atmospheric pressure have been frequently used to modify the surface properties of commercial polymers, due to their low process costs. This work reports the results of polyethylene terephthalate (PET), polyurethane (PU) and polytetrafluoroethylene (PTFE) treatments in plasma by dielectric barrier discharges (DBDs) in air, nitrogen and argon at atmospheric pressure. The plasma-modified surfaces were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The polymer surface, modified by DBD at atmospheric pressure, showed a significant decrease in water contact angle although a partial recovery of the surface wettability occurred during the first few days after the treatment. However, the process of hydrophobic recovery was insufficient for complete recovering of the samples original wettability. XPS analysis showed an increase of the oxygen concentration on the surface, due to the formation of polar groups, such as C-O and OC= O. A small increase in the concentration of nitrogen was also observed. AFM images exhibit an increased roughness of the treated polymers because of the physical interaction between the species generated in the discharge and the polymer surface. The activated surface and high surface tension of treated polymers should promote an enhancement of the polymer adhesion to paints and coatings.

Dans un contexte de croissance du trafic aérien et dans le but de réduire la consommation de carburant ainsi que les émissions de polluants dans l’atmosphère, l’avion de demain se doit d’être plus respectueux de l’environnement. Dans un objectif d’optimisation de ses performances aérodynamiques,d’importantes activités de recherche sont menées dans le monde pour étudier de nouveaux dispositifs de contrôle actif des écoulements en temps réel. Depuis une dizaine d’années, l’utilisation de la décharge à barrière diélectrique surfacique comme actionneur plasma pour le contrôle d’écoulements suscite un intérêt grandissant. Ce type d’actionneur permet de créer un plasma non-thermique capable de générer un écoulement basse vitesse, appelé vent ionique, qui interagit avec l’écoulement naturel en proche paroi pour l’amener dans un état souhaité. Les études expérimentales présentées dans cette thèse portent, d’une part, sur la caractérisation de l’actionneur plasma sous atmosphère contrôlée pour étudier le rôle de l’azote et de l’oxygène sur le comportement de la décharge et d’autre part, sur l’évaluation des potentialités de cet actionneur à contrôler le décollement massif naissant au bord d’attaque d’un profil d’aile placé à forte incidence. Les résultats mettent en évidence l’importance du rôle joué par O2 dans l’amorçage des filaments de plasma et dans la production de vent ionique. Le taux de production d’ozone de l’actionneur plasma a été quantifié en fonction de la puissance électrique. Les essais en soufflerie, réalisés dans le cadre du projet européen PLASMAERO, montrent l’effet de la fréquence de pulsation du signal d’alimentation haute tension sur la réponse de l’écoulement décollé et des ses instabilités naturelles. Il est ainsi possible, pour le profil placé à des incidences au-delà de l’incidence de décrochage naturel, d’augmenter la portance du profil en supprimant le décollement ou en favorisant la formation de tourbillons portants à l’extrados du profil. / To reduce power consumption and pollutant emissions in the atmosphere due to the increase of aerial traffic jam, tomorrow’s plane must be environnement-friendly. To enhance aerodynamic airfoil performance, worldwide studies have been carried out to study reel time active flow control actuators. For a decade, the interest in using a dielectric barrier discharge for flow control is increasing. Such a discharge is able to create a non thermal plasma which can induce a low velocity airflow, called ionic wind, which interacts with natural flow close to the wall to change its behavior. Experimental studies detailled in this thesis can be divided in two parts. On one hand, plasma actuator caracterization is performed at atmospherical pressure to study the influence of oxygen and nitrogen on the discharge behavior. On the other hand, abilities of the actuator to control a massive flow separation at the leading-edge of an airfoil in a deep post-stall regime are investigated. Results underlines that plasma filaments ignition and ionic wind generation is mainly governed by O2. Besides, the ozone procution rate of the dischage is measured as a function of electrical power. Wind tunnel tests, performed in the PLASMAERO project, underline that separated air flow and its instabilities can be drive by the burst frequency of the high voltage signal. For a deep post-stall regime, a lift enhancement can by obtained by reattaching the air flow or inducing lifting vortexes on the wing upper surface.

Having gained popularity in the last decade, the dielectric barrier discharge (DBD) has been studied in numerous ways as a device for air acceleration. A major interest of all these works has been concentrated on achieving higher efficiency and producing higher jet velocities. These studies considered alternative geometries, different voltage waveforms etc., yet none of these studies tackle the inherently inefficient process of force creation and actuation in a DBD. Air acceleration has been attributed to the electric force that switches direction on each voltage half cycle (that is due to the nature of the discharge mechanism) yet has a forward resulting force. The present thesis considers the phenomenon of memory charge accumulation on the dielectric surface and reasons that the backward force in the second half cycle can be reversed by further migration of the memory charges to an added exposed anode. Hence a novel 3-electrode configuration is presented. Flow velocity investigations showed a 27% improvement in efficiency in comparison with the traditional 2-electrode actuator. This meant a 0.4m/s gain along the velocity profile. During the investigation process, a new discharge mechanism was encountered. This was characterized by the double discharge lines along the exposed electrode edges while in the presence of a \"floating\" encapsulated electrode. / Tendo ganho popularidade na última década, a descarga de barreira dielétrica (DBD) foi estudada de várias maneiras como um dispositivo para aceleração do ar e controle aerodinâmico. Um grande interesse de todos esses trabalhos foi concentrado em alcançar maior eficiência e produzir maiores velocidades de jato. Alguns desses estudos consideraram geometrias alternativas, diferentes formas de onda de tensão, etc., mas nenhum desses estudos aborda o processo inerentemente ineficiente de criação e atuação da força em um DBD. A Aceleração do ar tem sido atribuída à força elétrica que muda de direção em cada meio ciclo (que é devido à natureza do mecanismo de descarga), mas que tem uma força resultante para a frente. A presente tese considera o fenômeno de acumulação de carga de memória na superfície dielétrica e raciocina que a força contraria no segundo meio ciclo da descarga pode ser revertida por migração dessas cargas de memória para um ânodo adicional exposto. Assim, uma nova configuração de 3 eletrodos é apresentada. Investigações de velocidade do fluxo mostraram uma melhoria de 27% na eficiência em comparação com o tradicional atuador de 2 eletrodos. Isso significou um ganho de 0,3 m/s ao longo do perfil de velocidade. Durante o processo de investigação, foi encontrado um novo mecanismo de descarga. Isso foi caracterizado por uma dupla descarga ao longo das bordas do eletrodos expostos, enquanto na presença de um eletrodo encapsulado \"pendurado\".