Les arcs électriques de défaut se produisant entre deux câbles endommagés peuvent donner lieu à un phénomène appelé " arc tracking ", qui se caractérise par le maintien et la propagation de cet arc le long des câbles, entraînant leur ablation progressive. Dans un réseau aéronautique, un tel défaut peut avoir de graves conséquences lorsqu'il apparaît au sein d'un toron de câbles, d'autant plus qu'il est susceptible de se transférer à une structure avoisinante. Un dispositif expérimental a été développé pour l'étude de ce phénomène. Il est constitué d'une alimentation conçue selon des spécifications propres au domaine aéronautique, permettant de générer un signal continu ou alternatif pendant une durée réglable. Afin de se rapprocher des conditions de vol (pression réduite à haute altitude), les essais sont effectués au sein d'une enceinte fermée, soit à 1 bar, soit à 95 mbar. Trois types de câbles sont testés, un en aluminium et deux en cuivre. En régime continu, ils sont reliés au + et au - de l'alimentation, et à deux phases en régime alternatif. Une plaque en aluminium, représentant la structure de l'avion et connectée au neutre du générateur en régime alternatif, est placée en regard de la partie dénudée des câbles, là où se produit l'arc, permettant un éventuel transfert de l'arc depuis les câbles vers cette plaque. Chaque test s'accompagne de l'acquisition systématique des signaux de courant et de tension, et deux capteurs de flux radiatif sont positionnés autour de l'arc. Une caméra rapide permet la visualisation du comportement de l'arc au cours de l'essai. Enfin, les échantillons de câbles sont pesés avant et après chaque test. Un bilan de puissance est réalisé pour les différentes configurations testées (courant, pression, câbles), afin d'estimer la répartition de la puissance totale entre les électrodes (fusion et vaporisation des câbles, conduction, rayonnement) et la colonne de plasma (rayonnement, conduction, convection). La part transférée aux électrodes est estimée au moyen de la valeur de la chute de tension aux électrodes et du courant. Une partie de cette puissance aux électrodes est à l'origine de la fusion et de la vaporisation des câbles (le matériau isolant comme le métal). Celle-ci est estimée grâce à un calcul thermodynamique à partir de la masse de câble ablatée, en considérant que la totalité a été fondue et que 1% a été vaporisé. La puissance transmise à la colonne d'arc est en partie rayonnée, mais le spectre de longueurs d'onde inférieures à 200 nm est absorbé dès les premiers microns d'air, et une estimation est effectuée à partir du calcul coefficient d'émission nette. Une partie importante de l'étude a porté sur le transfert de l'arc à la plaque en aluminium, en fonction de la distance entre les câbles et cette plaque et selon un critère de température en face arrière, mesurée par thermographie infrarouge. Il a ainsi été montré qu'à pression réduite l'arc est beaucoup plus diffus, et a tendance à s'accrocher à la plaque en aluminium à des distances environ deux fois plus grandes qu'à pression atmosphérique. Cependant, la puissance totale disponible étant inférieure d'environ 20%, les dégâts à la plaque en aluminium sont moins importants. / Fault electric arcs occurring between two damaged wires may lead to a phenomenon called "arc tracking", which consists in a maintaining and propagating arc along the cables, causing their progressive ablation. In an aeronautical network, such a fault may have serious consequences if it happens within a wiring harness, especially as it is likely to transfer to a nearby structure. An experimental setup has been developed to study this phenomenon. It consists of a power supply designed in accordance with aeronautical specifications, which enables to generate a direct or alternating signal during an adjustable time. In order to reproduce flight conditions in a better way (low pressure at high altitude), tests are carried out within a closed chamber, whether at 1 bar pressure, or at 95 mbar pressure. Three types of cables are tested, one mainly made of aluminium and two mainly made of copper. In direct regime, they are connected to the + and the - poles of the generator, and to two phases in alternating regime. An aluminium plate, representing the aircraft structure and connected to the neutral in alternating regime, is placed in front of the stripped part of the cables, where the arc occurs, enabling a potential transfer of the arc from the cables toward the plate. Every test involves a systematic acquisition of the current and voltage signals, and two radiative flux sensors are positioned around the arc. A fast camera enables a viewing of the arc behaviour during the test. Finally, the sample is weighed before and after each test. A power balance is realised for the various tested configurations (current, pressure, cables), in order to estimate the distribution of the total power between the electrodes (fusion and vaporisation of the cables, but also conduction and radiation) and the plasma column (radiation, conduction, convection). The amount of power that is transferred to the electrodes is estimated with the value of the electrode voltage drop and the current. Part of this power makes the cables melt and vaporise (the insulating material as well as the metal), it is estimated with a thermodynamic calculation based on the ablated mass of cable, considering that the whole has been molten, and 1% vaporised. The amount of power transmitted to the arc column is partly radiated, but the wavelength spectrum emitted below 200 nm is absorbed through the very first microns in air, and estimation is made involving the calculation of the net emission coefficient. A significant part of the study was related to the transfer of the arc toward the aluminium plate, as a function of the distance between the cables and that plate, and according to a temperature criterion at the back side, by means of infrared thermography. Thus, it was shown that at low pressure, the arc is much less localised, and tends to transfer to the aluminium plate at distances around twice bigger than at atmospheric pressure. However, the total available power is around 20% smaller, and the damage caused to the aluminium plate is less severe.

La nature intermittente et aléatoire des sources renouvelables, telles que le photovoltaïque et l’éolien, nécessite un complément de stockage, tel une batterie et un système de secours énergétique, tel un générateur diesel, en particulier dans un système autonome. En ce qui concerne le générateur diesel, il a besoin d'un certain temps pour démarrer et il ne peut pas donner immédiatement la puissance nécessaire, en raison de son comportement dynamique. Alors, la qualité de l'énergie est abaissée pendant cette période en raison du manque de puissance. Par conséquent, pendant la période de démarrage du générateur diesel, un supercondensateur est suggéré pour équilibrer la puissance en raison de sa réponse rapide et de sa densité de puissance élevée. Une stratégie de contrôle de puissance est proposée pour réaliser la coordination entre le générateur diesel et le supercondensateur. La simulation et les résultats expérimentaux montrent que la stratégie de contrôle proposée est capable de réguler la tension du bus continu dans des limites acceptables et d’alimenter la charge pendant la sous production d'énergie renouvelable ou lors d'augmentation de la demande de la charge. De plus, le supercondensateur peut également être utilisé pour surmonter les limites de stockage électrochimique telles que son état de charge et son courant maximal. Ainsi, cette thèse propose le contrôle de puissance en temps réel pour un micro réseau continu avec un système hybride photovoltaïque-batterie-supercondensateur-diesel, visant à répondre à la demande de puissance de charge avec fiabilité et à stabiliser de la tension du bus continu. La simulation et les résultats expérimentaux montrent également que la stratégie de contrôle améliore les performances dynamiques et statiques du micro réseau continu pour différentes conditions de fonctionnement. De plus, afin de minimiser le coût énergétique du groupe diesel, le coût du carburant et la consommation de carburant sont analysés à travers plusieurs tests expérimentaux. Par conséquent, la valeur optimale de sa production d'énergie est déduite et appliquée dans une nouvelle stratégie de gestion de la puissance est proposée. Cette stratégie peut atteindre l'objectif de maximiser l'utilisation de l'énergie photovoltaïque et de prendre en compte la caractéristique de démarrage lent et le coût énergétique du générateur diesel. Les simulations et expérimentations sont réalisées en utilisant des données photovoltaïques réelles pour illustrer les performances et le comportement du système hybride. Les résultats obtenus vérifient l'efficacité de cette stratégie. De plus la comparaison avec la stratégie de gestion de la puissance précédente, dans laquelle le coût d’énergie du générateur diesel n'est pas pris en compte, démontre que la nouvelle stratégie de gestion peut réduire le coût total du système de puissance à courant continu hybride. / The intermittent and random nature of renewable sources, such as photovoltaic and wind turbine, asks for the complement of storage, such as battery and back-up energy, such as diesel generator, especially in a standalone power system. Concerning the diesel generator, it needs some time to start up and cannot immediately offer the needed power, due to its dynamic behavior. Hence, the power quality is lowered down during this period because of the shortage of power. Therefore, during the period of the diesel generator starting up, a supercapacitor is suggested to compensate the power balance because of its fast response and high power density. A power control strategy is proposed to achieve the coordination between diesel generator and supercapacitor. Both simulation and experimental results show that the proposed control strategy is able to regulate the DC bus voltage within the acceptable limits and supplying the load during the renewable power under generation or load step-increase situations. In addition, the supercapacitor can be also used to overcome the electrochemical storage limits like its state of charge and maximum current. So, this thesis proposes the real time power control for a hybrid photovoltaic-battery-supercapacitor-diesel generator DC microgrid system, aiming to meet the load power demand with reliability and stabilizing the DC bus voltage. Both simulation and experimental results show that the designed control strategy improves the DC microgrid dynamic and static performances under different operating conditions. Furthermore, in order to minimize the diesel generator energy cost, the fuel cost and fuel consumption are analysed through several experimental tests. Therefore, the optimal value of its power generation is deduced and applied in a newly proposed energy management strategy. This strategy can achieve the goal of maximizing the utilization of photovoltaic energy and taking into account the slow start-up characteristic and energy cost of diesel generator. Both simulation and experimental studies are carried out by using the real photovoltaic data to illustrate the performance and the behavior of the hybrid system. The obtained results verify the effectiveness of this strategy. Furthermore, the comparison with the previous energy management strategy, in which the diesel generator energy cost is not considered, demonstrates that the newly proposed energy management strategy can reduce the total cost of the hybrid DC power system.

This work deals with the deployment of distributed power sources into the electric power grid. The nature of these sources causes that the massive integration may experience problems with power quality in the local context, and also overall reliability of supply in the range of interconnected power systems may be endangered. Work is focused on local voltage quality problems with special emphasis on analysis and design of tools (e.g. reactive power compensation units of power plants or dynamic voltage control by transformers 110/22kV) for voltage control in power distribution systems. These tools should be used as a part of uniform concept of voltage control. The proposed concept is involved.

Nowadays vehicle design paradigm influences not only the effectiveness of the different means of transport, but also the environment and economy in a critical way. The assessment of the consequences that design choices have on society at large are necessary to understand the limits of the methods and techniques currently employed. One of the mechanisms set in motion is the planned obsolescence of products and services. This has affected vehicle design paradigm in such a way that the variety in the market has shadowed the primary function of vehicle systems: the transport of persons and goods. Amongst the consequences of the expansion of such market is the exponential rise on combustion emissions to the atmosphere, which has become a great hindrance for humans health and survival of ecosystems. The development of evaluation tools for such consequences and their piloting mechanisms is needed so as to implement an ECO2  (Ecological and Economical) vehicle design paradigm. Moreover, the multifunctional design paradigm that drives aeronautical and vehicle engineering is an ever-growing demand of smart materials and structures, able to fulfil multiple requirements in an effective way. The understanding of certain phenomena intrinsic to the introduction of novel materials has found certain limits due to the complexity of the models needed. This work presents as a first step an assessment of the causes and consequences of the vehicle exponential market growth based on the analysis of the planned obsolescence within. Furthermore, a method for the acoustic response analysis of multilayered structures including anisotropic poroelastic materials is introduced. The methodology consists in a plane wave approach as a base for introducing the complex mechanic and acoustic equations governing anisotropic homogeneous media, e.g. open-celled foams, into an alternative mathematical tool manipulating physical wave amplitudes propagation within the studied media. In addition, this method is coupled to a power partitioning and energetic assessment tool so as to understand the phenomena present in complex multilayered designs. / <p>QC 20150323</p>

Der vorliegende Beitrag behandelt die kinematische und statische Analyse eines Biglide-Getriebes mit fünf Gliedern und zwei Schubantrieben zur Führung eines Punktes in der x-y-Ebene. Als mathematische Hilfsmittel werden die beiden Programme PTC Mathcad Prime 3.1 und GeoGebra 5.0 eingesetzt, die sich einander in hervorragender Weise ergänzen. Dabei ist Mathcad hier vorwiegend für Matrizenrechnungen und GeoGebra besonders anschaulich für geometrische Grundaufgaben mit Animationen zuständig. Die Effizienz der vorgestellten Algorithmen und Hilfsmittel wird anhand zweier Anwendungsbeispiele aufgezeigt.

Dans ce travail, nous proposons une approche essentiellement expérimentale. Dans une première partie, nous exposons les résultats obtenus par imagerie rapide et mesures électriques corrélées dans le temps, concernant l’étude de la transition entre des électrodes de cuivre dans l’air et l’argon, et entre des électrodes de tungstène dans l’argon pour des pressions comprises entre 100 mbar et 1 bar. Dans aucun cas une transition à l’arc n’est observée sans constriction quasi-totale de la colonne positive. Dans le cas d’électrodes en tungstène dans l’argon, la vitesse d’extension de la zone filamentaire depuis l’anode vers la cathode a été vue dépendante de la pression et de l’intensité. La durée d’une transition spontanée a été linéairement corrélée à la distance inter-électrode, suggérant un mécanisme propagatif à vitesse constante dans la colonne. Plus la pression est élevée, plus la durée totale des transitions est longue ; par ailleurs, à pression constante, cette durée de transition spontanée décroît à intensité croissante, pour tendre vers une durée limite, correspondant à la durée constante de changement de structure de la zone cathodique. Dans une seconde partie, nous nous intéressons à l’échauffement de surfaces d’anodes et de cathodes en cuivre dans l’air et dans l’argon soumises à des arcs électrique pour plusieurs gammes de courant (de 30 à 120 A). Deux méthodes de mesures sont utilisées. Enfin, nous utilisons les mesures de températures de surface pour proposer deux modèles simples de bilan de puissance à la surface des électrodes (flux de chaleur). L’un considère uniquement le chauffage dû au spot d’arc et l’autre le chauffage supplémentaire de la colonne d’arc. / In this work, an approach which is essentially experimental is proposed. In the first part, results are presented which were obtained by synchronized fast camera imaging and electrical measurements. These concern the study of the transition between copper electrodes in air and in argon, and between tungsten electrodes in argon for gas pressure in the range 100 mbar – 1 bar. In no case was the transition to arc been observed without the quasi-total constriction of the positive column. Considering tungsten electrodes in argon, the propagation speed of the filamentary part of the positive column from the anode to the cathode was found to be dependent on the gas pressure and the discharge current intensity. During spontaneous transition, the transition duration has been linearly correlated to the electrode gap, suggesting a propagative mechanism with a constant speed. The higher the pressure, the longer is the total transition duration. For a constant pressure and discharge current, the duration of spontaneous transition decreases with decreasing gap distance toward a limiting value, which corresponds to the constant duration of the structural change of the cathode root from diffuse to spot. In the second part, heating of copper anodes and copper cathodes submitted to electric arcs in air and in argon and for various current intensity values (from 30A to 120 A) is considered. Two measurement methods are used. Finally, the surface temperature measurements are used to purpose two models of the electrode surface power balance (heat flux). One model only considers the heating due to the arc spot and the second one considers a supplementary heating from the arc column.

O estudo visa à análise configuracional do Orçamento Participativo de Porto Alegre (OPPA) de 1989 a 2004. Enfoca a possibilidade, ou não, de experiências de participação popular na co-gestão dos recursos orçamentários do Município democratizar as relações entre o Poder Público Local (Estado) e a comunidade (Sociedade Civil), possibilitando um equilíbrio de poder mais horizontal entre os participantes e gerando novos hábitos de participação popular. Parte-se de um referencial teórico constituído de três dimensões analíticas: (1) a produção de uma nova configuração no processo de institucionalização da participação popular na gestão dos recursos orçamentários municipais, que se fundamentam na proposta de análise configuracional de Elias e no conceito de Institucionalização de Berger e Luckmann. (2) Os processos de participação popular da co-gestão de instituições públicas no Brasil e seus limites para a cidadania, com base em Oliveira, Buarque de Holanda, Murilo de Carvalho e outros autores nacionais. (3) As possibilidades da configuração de novos hábitos democráticos, que refletem-se sobre os modelos normativos de Democracia e as motivações para a participação em processos de democratização do Estado, com referência básica em Habermas e Cohen e Arato. Postularam-se duas hipóteses de investigação. De um lado, uma tendência à democratização político-social, expressa em novas formas de tecnologias institucionais, e conseqüentemente, na instituição de novos hábitos democráticos a partir de uma nova dinâmica participativa que estimula as ações coletivas autônomas. De outro lado, a tendência à trivialização político-social do Orçamento Participativo, que se caracteriza por uma hiper-especialização da participação no processo, de forma pragmática e fragmentária. Os resultados encontrados indicam o acontecimento de duas situações configuracionais diferenciadas ao longo dos 16 anos de realização da experiência do Orçamento Participativo de Porto Alegre. Uma tendência à democratização político-social e uma tendência à trivialização político-social do processo de participação com ênfase na fragmentação e no reforço de ações pragmáticas. / The study aims a configurational analysis on Porto Alegre´s Participatory Budget (OPPA) from 1989 to 2004. It has brought the possibility, or not, of such popular participation experiences in the co-management of the budgetary city resources, to democratize the relationship between the local public power (Province) and the community (Civil Society), making possible a more horizontal balance power between the participants and generating new habits of popular participation. Starting from a theoretical reference constituted of three analytical dimensions: (1) the production of a new configuration in the process of institutionalization of the popular participation in the management of the city budgetary resources, which is based on Elias configurational analysis proposal and on the Institutionalization concept of Berger and Luckmann. (2) The processes of popular participation in the co-management of public institutions in Brazil and its limits for the citizenship, based in the works of Oliveira, Buarque de Holanda, Murilo de Carvalho, among others important national authors. (3) The configurational possibilities of new democratic habits, that reflect on the normative models of democracy and the motivations for the participation in processes of democratization of the Province, by basic reference on Habermas, Cohen and Arato. In this context, two hypotheses of inquiry were postulated. At one side, a tendency to social political democratization expressed on new forms of institutional technologies and, due to that, for the institution of new democratic habits starting from new participatory dynamics that stimulate the independent collective actions. On the other side, the accomplishment of a tendency to the social political trivialization that is, inversely, characterized by a hiper-specialization of the participation in the process in a pragmatic and fragmentary way. The obtained results indicate two different situations concerning the configurations throughout the 16 years of the accomplished experience: the event of a tendency to the social political democratization and, inversely, a tendency to the social political trivialization of the participation process with emphasis on the fragmentation and reinforcement of pragmatic actions.

O estudo visa à análise configuracional do Orçamento Participativo de Porto Alegre (OPPA) de 1989 a 2004. Enfoca a possibilidade, ou não, de experiências de participação popular na co-gestão dos recursos orçamentários do Município democratizar as relações entre o Poder Público Local (Estado) e a comunidade (Sociedade Civil), possibilitando um equilíbrio de poder mais horizontal entre os participantes e gerando novos hábitos de participação popular. Parte-se de um referencial teórico constituído de três dimensões analíticas: (1) a produção de uma nova configuração no processo de institucionalização da participação popular na gestão dos recursos orçamentários municipais, que se fundamentam na proposta de análise configuracional de Elias e no conceito de Institucionalização de Berger e Luckmann. (2) Os processos de participação popular da co-gestão de instituições públicas no Brasil e seus limites para a cidadania, com base em Oliveira, Buarque de Holanda, Murilo de Carvalho e outros autores nacionais. (3) As possibilidades da configuração de novos hábitos democráticos, que refletem-se sobre os modelos normativos de Democracia e as motivações para a participação em processos de democratização do Estado, com referência básica em Habermas e Cohen e Arato. Postularam-se duas hipóteses de investigação. De um lado, uma tendência à democratização político-social, expressa em novas formas de tecnologias institucionais, e conseqüentemente, na instituição de novos hábitos democráticos a partir de uma nova dinâmica participativa que estimula as ações coletivas autônomas. De outro lado, a tendência à trivialização político-social do Orçamento Participativo, que se caracteriza por uma hiper-especialização da participação no processo, de forma pragmática e fragmentária. Os resultados encontrados indicam o acontecimento de duas situações configuracionais diferenciadas ao longo dos 16 anos de realização da experiência do Orçamento Participativo de Porto Alegre. Uma tendência à democratização político-social e uma tendência à trivialização político-social do processo de participação com ênfase na fragmentação e no reforço de ações pragmáticas. / The study aims a configurational analysis on Porto Alegre´s Participatory Budget (OPPA) from 1989 to 2004. It has brought the possibility, or not, of such popular participation experiences in the co-management of the budgetary city resources, to democratize the relationship between the local public power (Province) and the community (Civil Society), making possible a more horizontal balance power between the participants and generating new habits of popular participation. Starting from a theoretical reference constituted of three analytical dimensions: (1) the production of a new configuration in the process of institutionalization of the popular participation in the management of the city budgetary resources, which is based on Elias configurational analysis proposal and on the Institutionalization concept of Berger and Luckmann. (2) The processes of popular participation in the co-management of public institutions in Brazil and its limits for the citizenship, based in the works of Oliveira, Buarque de Holanda, Murilo de Carvalho, among others important national authors. (3) The configurational possibilities of new democratic habits, that reflect on the normative models of democracy and the motivations for the participation in processes of democratization of the Province, by basic reference on Habermas, Cohen and Arato. In this context, two hypotheses of inquiry were postulated. At one side, a tendency to social political democratization expressed on new forms of institutional technologies and, due to that, for the institution of new democratic habits starting from new participatory dynamics that stimulate the independent collective actions. On the other side, the accomplishment of a tendency to the social political trivialization that is, inversely, characterized by a hiper-specialization of the participation in the process in a pragmatic and fragmentary way. The obtained results indicate two different situations concerning the configurations throughout the 16 years of the accomplished experience: the event of a tendency to the social political democratization and, inversely, a tendency to the social political trivialization of the participation process with emphasis on the fragmentation and reinforcement of pragmatic actions.

O estudo visa à análise configuracional do Orçamento Participativo de Porto Alegre (OPPA) de 1989 a 2004. Enfoca a possibilidade, ou não, de experiências de participação popular na co-gestão dos recursos orçamentários do Município democratizar as relações entre o Poder Público Local (Estado) e a comunidade (Sociedade Civil), possibilitando um equilíbrio de poder mais horizontal entre os participantes e gerando novos hábitos de participação popular. Parte-se de um referencial teórico constituído de três dimensões analíticas: (1) a produção de uma nova configuração no processo de institucionalização da participação popular na gestão dos recursos orçamentários municipais, que se fundamentam na proposta de análise configuracional de Elias e no conceito de Institucionalização de Berger e Luckmann. (2) Os processos de participação popular da co-gestão de instituições públicas no Brasil e seus limites para a cidadania, com base em Oliveira, Buarque de Holanda, Murilo de Carvalho e outros autores nacionais. (3) As possibilidades da configuração de novos hábitos democráticos, que refletem-se sobre os modelos normativos de Democracia e as motivações para a participação em processos de democratização do Estado, com referência básica em Habermas e Cohen e Arato. Postularam-se duas hipóteses de investigação. De um lado, uma tendência à democratização político-social, expressa em novas formas de tecnologias institucionais, e conseqüentemente, na instituição de novos hábitos democráticos a partir de uma nova dinâmica participativa que estimula as ações coletivas autônomas. De outro lado, a tendência à trivialização político-social do Orçamento Participativo, que se caracteriza por uma hiper-especialização da participação no processo, de forma pragmática e fragmentária. Os resultados encontrados indicam o acontecimento de duas situações configuracionais diferenciadas ao longo dos 16 anos de realização da experiência do Orçamento Participativo de Porto Alegre. Uma tendência à democratização político-social e uma tendência à trivialização político-social do processo de participação com ênfase na fragmentação e no reforço de ações pragmáticas. / The study aims a configurational analysis on Porto Alegre´s Participatory Budget (OPPA) from 1989 to 2004. It has brought the possibility, or not, of such popular participation experiences in the co-management of the budgetary city resources, to democratize the relationship between the local public power (Province) and the community (Civil Society), making possible a more horizontal balance power between the participants and generating new habits of popular participation. Starting from a theoretical reference constituted of three analytical dimensions: (1) the production of a new configuration in the process of institutionalization of the popular participation in the management of the city budgetary resources, which is based on Elias configurational analysis proposal and on the Institutionalization concept of Berger and Luckmann. (2) The processes of popular participation in the co-management of public institutions in Brazil and its limits for the citizenship, based in the works of Oliveira, Buarque de Holanda, Murilo de Carvalho, among others important national authors. (3) The configurational possibilities of new democratic habits, that reflect on the normative models of democracy and the motivations for the participation in processes of democratization of the Province, by basic reference on Habermas, Cohen and Arato. In this context, two hypotheses of inquiry were postulated. At one side, a tendency to social political democratization expressed on new forms of institutional technologies and, due to that, for the institution of new democratic habits starting from new participatory dynamics that stimulate the independent collective actions. On the other side, the accomplishment of a tendency to the social political trivialization that is, inversely, characterized by a hiper-specialization of the participation in the process in a pragmatic and fragmentary way. The obtained results indicate two different situations concerning the configurations throughout the 16 years of the accomplished experience: the event of a tendency to the social political democratization and, inversely, a tendency to the social political trivialization of the participation process with emphasis on the fragmentation and reinforcement of pragmatic actions.

In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. The improvements of a new over-determination method for the source part of the N-port is studied using simulations and measurements; in quiescent air as well as measurements of the flow associated noise of a mixer plate, here a triangular plate inserted at an angle in a duct. The new method is shown to improve suppression of random errors while no improvement is achieved for bias errors.   Further, the methods are applied in the study of two different aeroacoustic phenomena; one is the effect on the flow associated noise of the triangular plate achieved by varying the bending stiffness. For the most resilient plate tested, it is observed that when the Strouhal number of the flow noise coalesce with the Helmholtz number of a specific eigen-mode of the plate, the noise is drastically dampened. There is also a weaker broad band effect.   The other phenomena studied is the amplification and attenuation obtained for sound waves propagating in a T-junction of rectangular ducts. It is found that by adding only 10% of inflow in the side branch relative to that in the main branch, the amplification is heavily increased. By adding another 10% the amplification is again similar to that of no side branch flow. Adding further flow lessens the effects still. / QC 20101118 / Experimental characterization of aero-acoustic sources