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Arbetet syftar till att ta fram en hållbar infästning för virveldämpare till SSRS drönare av modell flygande vinge. Drönaren är specifikt framtagen för att användas till maritima sök och räddningsuppdrag och för att bidra till att utöka den svenska kustens säkerhet. Arbetet studerar ett landningsscenario för drönaren och utifrån detta tas en ny infästning fram. Infästningen av virveldämparen skall vara lätt att hantera för personalen, kräva minimalt med reparation och hålla för 50 landningar. Infästningen skall kunna utlösa och separera virveldämparen från vingen om det under landningen uppstår så stora krafter att dessa komponenter riskerar att ta skada. Arbetet följer DRM-struktur och syftar till att ta fram en prototyp med hjälp av en uttömmande idégenerering utförd med metoderna Speedstorming, Brainstorming och SCAMPER. Konceptsållningen sker med hjälp av anpassade poängsättningsmetoder och Pugh-analys. Det resulterande konceptet bestämmer vilka dimensioner som krävs för att kunna utföra hållfasthetsberäkningar på den valda infästningen, därefter skapas en prototyp vilken används för att utföra hållfasthetstester. De utförda beräkningarna och testerna gav olika resultat och den därav dragna slutsatsen medförde att materialegenskaper rörande elastisk deformation och variabler på hållfasthetstestet ej har beaktas. Testerna visade att den framtagna prototypen av expanderad polypropen hanterade de förutsedda krafterna väl även om testerna inte kunde utföras under helt verklighetstrogna landningsförhållanden. Slutresultatet av projektarbetet är att den framtagna infästningen av virveldämparen har, utifrån tillgängliga testningsmetoder, påvisat önskade egenskaper och att utförligare tester behöver genomföras för att avgöra om den uppfyller samtliga produktkrav. / This work is aimed at producing durable attachments for winglets on a drone, model flying wing, owned by the SSRS. The drone is specifically developed to be used for maritime search and rescue missions and to contribute to increasing the security along the Swedish coast and major inland lakes. During this work only one landing scenario by the drone was studied while creating the attachments, which required to be easy to handle, minimal to no repair work and a durability for 50 landings. The attachments also need to be able to release in case of excessive force during landing which risks jeopardizing the integrity of the wing or winglet. The work followed the DRM-structure and aimed to create a prototype through an exhaustive idea generation technique in three steps using the methods Speedstorming, Brainstorming and SCAMPER. All of these methods go through voting, Pugh analysis and concept screening. After one concept had been singled out its dimensions were decided on and used in calculations to determine its strength. From this information a physical winglet attachment prototype made of expanded polypropylene was created and used in strength and durability tests. Calculations and tests were found to have varying results and the conclusion was made that the material properties regarding elastic deformation and test variables most likely had not fully been taken into account. The tests failed to generate a realistic landing scenario given the requirements but still gave a positive result concerning the prototype's ability to absorb shock loads at landing. This work has resulted in a preliminary winglet attachment prototype which through testing has shown satisfying shock absorbing abilities, and that further testing is required to decide whether the attachment can meet all of the set product requirements.

Due to mass and volume constraints on planetary missions, the development of control techniques that do not require fuel are of big interest. For those planets that have a dense enough atmosphere, aerodynamic drag can play an important role. The use of atmospheric differential drag for formation keeping was first proposed by Carolina L. Leonard in 1986, and has been proven to work in Earth atmosphere by many missions. Moreover, atmospheric drag has been used in the Mars atmosphere as aerobraking technique to decelerate landing vehicles, and to circularize the orbit of the spacecraft. Still, no literature was available related to formation flying on Mars. To analyze the use of differential drag on the Mars atmosphere, the researcher accessed the two high resolution models available: NASA’s Mars-GRAM and ESA’s Mars Climate Database. These models allowed the simulation of conditions that a spacecraft would experience while in orbit around the planet. To explore the feasibility, the researcher first conducted a study where Mars atmosphere density was compared to Earth atmosphere, determining its applicability. Then, a simulation using MATLAB® was conducted, using a Keplerian two-body problem including the effects of Mars zonal harmonics (i.e. J2) and drag perturbations. Two 6U CubeSat were used in the simulation with deployable drag plates of different sizes, giving the possibility of having five differential drag scenarios as means of formation control. The conclusions showed that, although with some limitations, the use of differential drag as means of autonomous formation flying and proximity operations control is feasible using proven techniques previously validated in Low Earth Orbit. Lyapunov control was selected as the control strategy, where three different methods were evaluated and compared.

The demand for high-power converters are surging due to applications like renewable energy, motor drives and grid-interface applications. Typically, these converters’ power ranges from tens of kilowatts (kW) to several megawatts (MW). To reach such high power levels the converter voltage ratings must increase, as the current ratings cannot be reached by the available devices or because the system losses become excessive. To address this, two strategies can be utilized: multilevel topologies (e.g. Multilevel Modular Converter or Flying Capacitor Multilevel Converter) and high voltage switches. For medium voltage applications, the most commonly employed switches are the IGBT and the IGCT. Both are silicon-based technology and are limited to a rated voltage of 6.5 kV and 4.5 kV, respectively. Often, these devices switching frequency are limited to less than 1 kHz. To expand the frontiers of medium voltage converters and to demonstrate the capabilities of wide band gap devices in medium voltage, a 7-level 13.8 kV AC 22 kV DC 1.1 MW flying capacitor multilevel converter based on 10 kV SiC MOSFET with 2.5 kHz switching frequency was designed and constructed. Given the complexity of a multilevel topology, the high voltage levels, and the critical nature of the loads, a failure in a high-power converter can incur significant costs, long service downtime, and safety risks to personnel. Hence, understanding the failure modes of these converters is essential for designing protections and mitigation strategies to prevent or reduce the risks of failures. Furthermore, the adoption of 10 kV SiC MOSFET introduces additional challenges in terms of protection. Despite their well-known benefits, these devices exhibit shorter energy withstanding time compared with their silicon counterpart, and increased insulation stress resulting from the high dv/dt imposed by the fast-switching transient at higher voltages. In this context, a failure mode analysis was conducted for the converter aforementioned. The analysis examined the fault dynamics and evaluated the protections schemes at the converter level. The study identified a failure mechanism between cells, so called Cell Short- Circuit Fault (CSCF), capable of damaging the entire phase-leg. In response, a protection scheme based on TVS (Transient Voltage Suppression) diodes was designed to prevent extremely imbalanced cell voltages and failure propagation. Because of the high electric field intensity environment of the converter, an FEA (Finite Element Analyses) simulation is performed to verify and control the electric field (E-field) intensity within the protection module itself and in the converter assembly. Next, the protection module insulation design was successfully verified in a Partial Discharge (PD) experiment. In sequence, an experimental verification utilizing an equivalent circuit based on the fault model demonstrated the efficacy of the protection module. Waveforms extracted while the converter was operating showing the protection module acting during a fault are presented and analyzed. Finally, the influence of the protection module in the switching of the 10 kV SiC MOSFET was evaluated via a double pulse test (DPT), revealing negligible effects on the converter performance. / Center of Power Electronics Systems (CPES) Department of Energy (DoE) / Master of Science / Due to governmental policies and market opportunities renewable energy (e.g. solar and wind energy) is increase its share in the electricity generation in the US and around the world. This scenario poses challenges regarding the stability of the grid and variation in the generation along the day. One of the alternatives to alleviate the problem is to use highpower converters that provides a interface between grid and manufacturing plants. This type of converter have bidirectional capabilities and can store the energy generated by solar farms during the day and return it to the grid at night for example. Moreover, it can provide grid support capabilities in terms of variation of frequency and voltage. To expand on the grid interface converters application concept, a medium voltage power converter in 22 kV DC and 13.8 kV AC is designed utilizing novel techniques and the latest technologies in semiconductors, 10 kV SiC MOSFETs. The benefits of this design are a small form factor, high efficiency, immunity to electromagnetic interference and power quality. This work presents a failure mode analysis of the power converter aforementioned, the analysis examined the fault dynamics and an evaluation of the protections schemes at the converter level. The failure analysis revealed the need of a protection scheme extremely imbalanced cell voltages and failure propagation. Hence, a protection module based on TVS (Transient Voltage Suppression) diodes was successfully designed and tested. Due to the high voltages present in this equipment, an FEA (Finite Element Analyses) simulation is performed to verify and control the electric field (E-field) intensity within the protection module itself and in the converter assembly. Experimental results are provided for insulation design integrity (partial discharge test), for the efficacy of the protection module against the fault, and for the impact of the protection module on the operation performance.

Cette thèse porte sur les effets des croyances dans la production des faux souvenirs, phénomène qui présente une importance toute particulière dans le contexte judiciaire. Nous avons trouvé avec le CNES (Centre National d’Études Spatiales) un terrain d’étude particulièrement fonctionnel pour comprendre les mécanismes de la production des faux souvenirs. En effet, le CNES a créé un service, le GEIPAN (Groupe d’Études et d’Informations sur les Phénomènes Aérospatiaux Non Identifiés), chargé de recueillir les témoignages à propos de PAN (Phénomènes Aérospatiaux Non identifiés) sur le territoire français. Le GEIPAN reçoit un volume conséquent de témoignages (en moyenne deux par jour) qui présentent bien souvent une grande homogénéité. Cette collaboration avec le CNES a permis de réaliser des études de terrain qui, articulées avec des études expérimentales de laboratoire, ont permis de mettre en évidence les conditions de production des faux souvenirs. Nous observons que les faux souvenirs sont dus à l’impact des croyances (ici à propos des OVNI) dès lors qu’un délai a permis une confusion entre différentes sources du souvenir. Dans une dernière partie de la thèse, nous montrons que l’adaptation d’une technique d’entretien judiciaire (l’entretien cognitif sur internet) à la problématique de ces témoignages permet de résoudre en partie la production des faux souvenirs. Nous évoquons dans la discussion les pistes d’utilisation des travaux de cette thèse dans le contexte des enquêtes judiciaires. / This doctoral dissertation focuses on the impact of beliefs on the development of false memories. Such memories have been reported to be important as far as the judicial system is concerned. The CNES (Centre National d’ Études Spatiales) has been an ideal study site for a depth understanding of the development of false memories. Indeed, the CNES has developed the GEPAN (Groupe d’Études et d’Informations sur les Phénomènes Aérospatiaux Non Identifiés), a service aiming to collect French testimonies regarding PAN (Phénomènes Aérospatiaux Non identifiés). The GEIPAN receive plenty of testimonies (2 testimonies per day). This collaboration with the GEIPAN allowed to conduct both field researches and experimental studies aiming to highlight processes leading to false memories. False memories were related to beliefs about UFOs as long as a period led to a confusion between the several sources memories. In a last part of this doctoral dissertation, the adaptation of judicial interview (cognitive interview on the Internet) for these testimonies will be presented as well as its utility to for solving a part of false memories. These findings and their utility in criminal investigation will be discussed in the discussion section.

Cette thèse s’inscrit dans le domaine de l’automatique, et a pour but de fournir des outils utiles à l’atterrissage en mer d’hélicoptères (sur navire ou plateforme) et employés dans le cadre d’un potentiel pilotage automatique. L’objectif a donc été de développer une série de lois de commande pilotées manuellement, puis commandées de façon autonome à l’aide d’informations caméra. Les lois ainsi développées à l’aide de modèles dynamiques d’hélicoptères, limitations mécaniques incluses, se basent sur les critères de Qualité de Vol issus de la norme ADS-33. L’ensemble a fait appel à une approche anti-windup pour améliorer la robustesse face aux situations d’actionneurs en saturation. Enfin les lois issues de ces travaux ont été testées en temps-réel sur le banc de pilotage d’hélicoptères de l’ONERA Salon-de-Provence. / This thesis is related to the automatic & control engineering field, and itsmain goal is to provide useful tools for ship landing missions, tools that can be used fora potential autopilot. The objective has been to develop a series of control laws manuallypiloted, then automatically controlled by visual servoing using identified image features. Thelaws developped thanks to helicopter models with mechanical limitations were based on flyingqualities criteria from the ADS-33 standard. The process also defines an anti-windup approachto cope with actuator saturations. Finally the main results were assessed in real time withthe ONERA rotorcraft flight test bench at ONERA Salon-de-Provence.

Virtual reality exposure therapy (VRET) is a treatment often used to treat fear-of-flying (FOF), which research shows is effective for treating this phobia. Researchers have identified that the realism of the virtual environment is an important component in the efficacy of VRET and increased realism is likely to increase the efficacy of VRET. Guided by cognitive theory, emotional processing theory, and behaviorism, the purpose of this quantitative study was to demonstrate if a new generational technique called true reality-virtual reality exposure therapy (TR-VRET) is at least as efficacious as traditional VRET for treating the fear and anxiety associated with FOF. Repeated measures ANOVAs were used to compare the means between the pre-/posttests measuring fear and anxiety associated with FOF and between the control and experimental group. Both the active treatment experimental group (using TR-VRET) and the active treatment control group (using VRET) had a significant effect on reducing anxiety related to flying. The findings also revealed that both the active treatment experimental group and the active treatment control group had a significant effect on reducing fear related to flying. Notably, no significant differences were found between the active treatment experimental group and the active treatment control group, meaning the 2 treatments were equally effective at reducing the anxiety and fear related to flying. These findings can contribute to positive social change by allowing mental health professionals access to an advanced treatment tool (i.e., TR-VRET) that is just as effective as the older treatment tool (i.e., VRET). These findings can also contribute to positive social change by quickly allowing more tailored virtual environments to be created for clients at a lower cost.

Este trabalho apresenta uma breve revisão histórica sobre asas voadoras, aeronaves sem uma cauda ou empenagem convencional. São apresentadas algumas características aerodinâmicas importantes para esse tipo de projeto e quais são os conceitos fundamentais que devem ser abordados pelo projetista. Na sequência é apresentado o software OpenFOAM, usado para simular o escoamento e obter forças e momentos aerodinâmicos, que são então comparados com dados experimentais de túnel de vento. / This work presents a brief historical review on flying wings, tailless aircraft without a conventional empennage. Some important aerodynamic characteristics are presented for this type of project and which are the fundamental concepts that must be approached by the designer. Following is the OpenFOAM software introduced, used to simulate the flow and obtain the aerodynamic forces and moments, which are then compared with experimental wind tunnel data.

Between 1914 and 1945 the Australian air services, the Australian Flying Corps (AFC ??? 1914 to 1919), the Australian Air Corps (AAC ??? 1920 to 1921) and their successor, the Royal Australian Air Force (RAAF ??? 1921 to 1945), developed from a marginally effective air arm into a major air force with a continental strike capability. The interwar period saw a series of pioneering flights which not only laid the foundations for the air defence of Australia but also assisted in national development. Essential to the development of the AFC and the RAAF was the practice of air navigation. While much has been written on World War II RAAF operations, almost nothing has been published on the policy, training and practice of air navigation in support of wartime operations or the interwar period. This omission is addressed by the examination of air navigation in the AFC and the RAAF from the rudiments of World War I to the emergence of air navigation as a critical specialist function which culminated in its practice in World War II tactical and strategic air operations. It was the wartime development of Australian air power between 1939 and 1945, and the parallel practice of advanced navigation techniques, that underscored Australia???s contribution to the allied air offensive.

<p>The purpose of this dissertation is to study the fantastic in the tales of the Italian children’s author Gianni Rodari. This analysis is grounded in the hypothesis that the fantastic is primarily characterized by two <i>esthetic qualities</i>, play and lightness, both of which are manifested at different levels in these texts, as well as in the relation between children and adults.</p><p>As a background for the textual analysis in the present work, an introductory review is provided of previous research, followed by a historical and theoretical consideration of fantastical children’s literature, together with a study of Rodari’s own relation to the fantastic. For previous research, the results clearly indicate an arbitrary relationship to Rodari’s texts, such that the fantastic is admittedly recognized, but is often confused with the fairy-tale. However, the present review of the history of Italian fantastical literature for children indicates that Rodari is writing in a fantastical and humorous tradition that begins with <i>Pinocchio</i>, a tradition that is <i>inter alia </i>characterized by its ability to bridge the gap between children’s and adult literature. Based on theoretical definitions of the fairy-tale (Propp, Thompson, Lüthi) and the fantastic (Todorov, Rabkin, Jackson, Held), the present work presents its own model for the study of Rodari’s texts, which are also compared with the author’s own poetics,<i> The Grammar of Fantasy.</i></p><p>A narratological analysis of a tale with both a children’s and an adult version (in itself an example of <i>crosswriting</i>) demonstrates that the fantastic and the humoristic are given freer rein when Rodari is writing for children. This appears to be linked to his concept of the child as the ideal reader, a reader primarily defined by an open and unprejudiced attitude to literature, rather than by age <i>per se</i>. The dissertation’s study of play and lightness (lack of weight) clearly confirms the hypothesis that these elements are a major component of the fantastic in Rodari’s texts; the results nevertheless indicate that play dominates on the level of language, and lightness on that of content.</p><p>One of the most important results of this dissertation is that Rodari’s texts, in addition to possessing certain stylistic characteristics, do not demonstrate any deeper similarities to fairy tales. Instead, the author’s tales share numerous characteristics with the traditional concept of the fantastic such as a clear reaction to the supernatural element, and a particular interest in both the material nature of language and existential liminal regions. At the same time, the results indicate several specific characteristics that distinguish the fantastic in Rodari from that which is written for adults, such as its explicit grounding in the child’s everyday existence and imaginative world, as well as its backgrounding of frightening aspects, with prominence instead being given to playfulness.</p>