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Beacons & Internet of Things : A design concept for contect-aware mobile interaction with beaconsSelezneva, Nadia, Juskova, Aleksandra January 2014 (has links)
Mobile technology is developing quickly and becomming a part of daily life and communication. Bluetooth Low Energy is presented as a new way of mobile interaction. However there are not enough studies in this field on the interaction between mobile devices and the physical world. In order to understand user needs, and to encourage users to interact, we simulated an interaction process through designing and testing a prototype in a specific indoor environment. Prototype effectiveness and main characteristics for future mobile application was evaluated through a qualitative user study with 20 participants who interacted with our prototype. / Den mobila tekniken växer snabbt och blir en del av våra liv och vår kommunikation. BLE presenteras på ett nytt sätt inom mobilinteraktion. Det förekommer inte tillräckligt med studier inom området för interaktionen mellan mobila enheter och den fysiska världen. För att förstå användarbehov och få användare att interagera har vi simulerat en interaktiv process genom att designa och testa en prototyp i en specifik inomhusmiljö. Utvärdering av prototypens effektivitet och heuristiken har evaluerats genom en kvalitativ studie med 20 användare som har deltagit i interaktionen med vår prototyp.
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Development of a Bluetooth controller for mobile VR headsetsHolmberg, Tommy January 2018 (has links)
Mobile virtual reality (VR) headsets have been becoming more and more popular. However, the cheapest headsets do not come with any controllers and the ones that do include controllers only uses sensors for rotation, not translational movement. This thesis project aims to develop a prototype of a Bluetooth connected controller for the mobile VR headsets. The controller is based on a MetamotionC board produced by mbientlab Inc., which comes with Bluetooth Low Energy (BLE), an ARM M4 microcontroller, an miniature inertial measurement unit (IMU) sensor (containing a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer and a barometer), a thermometer and other sensors. The only sensors used in this project are the accelerometer, gyroscope, and magnetometer. As a finished prototype, the MetaMotionC is placed on a glove together with five Aruco markers; a 3D model of a hand intended to use as an avatar of the glove was made with Blender and MakeHuman; and a VR room to use the controller with was created in Unity. The 3D hand responds to rotational and translational movements via Bluetooth connection to the IMU sensor on the MetaMotionC. The smartphone camera is used to detect the glove's position with Aruco markers, and the 3D hand is moved to a corresponding location in the VR room. The OpenCV library is used for image processing. The sensor data is filtered with low-pass, median, and thresholding to improve the measurement accuracy. Zero velocity update is used to reset the drift of the integrated accelerations. To reduce the integration error, Romberg's method with a floating window is implemented in Matlab. However, it did not reduce the error enough to make a difference. Thus, the result was unreliable.
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Fuktanalys av kallvind i ett befintligt lågenergihus med hjälp av WUFI och en praktisk fältstudie / Moisture analysis of a cold attic in a low energy house with the use of WUFI and a field studyTrandem, Kevin, Loberg, Karl January 2017 (has links)
Issues related to moisture are one of the most common problems buildings are exposed to. Moisture issues have a tendency to lead to damage and growth of unwanted microorganisms on the buildings structure. Buildings troubled of issues related to moisture may have a negative impact on the indoor environment, the health of the people living there and the abrasion resistance of the structure. According to a research published by Boverket in 2010, approximately 36 % of all buildings in Sweden suffers from damage and mold in relation with moisture, most troubled by these kind of issues are small houses. More specifically, the attic in small houses is the most troubled part. The cost of maintenance for the damage caused by moisture is estimated to 91,2 billion SEK. The origin of moisture issues can depend on several different factors. Weather and climate are of great meaning if a building will be exposed to moisture issues. Precipitation, air humidity, temperature, wind speed and wind direction are some contributing factors. Today, constructing energy-saving buildings is a hot topic and a consequence of the more strict regulations regarding energy consumption. The sector of construction and service stands for approximately 40 % of Swedens total consumption of energy. Due to the topic of houses with a low consumption of energy, new ideas have come forward through the years and a typical example is the concept: Low energy house. Low energy houses are projected as dense houses with a high amount of insulation included with purpose to minimize the loss of thermal energy. Debates regarding how low-energy house has an increased risk to exposure of moisture issues than traditional houses as a consequence to a more dense structure, is common. Theoretically, low-energy houses have an increased risk for exposure but it can be avoided depending on the layout of the house and knowledge of moisture issues. Cold attics constitute a room in the attic where the climate has a resemblance to the outdoor climate. Former studies show a trend that cold attics have an increased risk for exposure of mold growth as a consequence to moisture issues. A low-energy house with a cold attic should, according to what is stated above, make a great risk for exposure of moisture issues. In this study a moisture analysis is performed of a cold attic in a low-energy house. The house is located in Molkom, Värmland and is relatively new-built. The goal with the analyzation is to examine if parts of the cold attic has a risk to be exposed to mold due to moisture issues and with relation to weather factors. The analyze was performed using two separate methods: a field study where moisture-measuring equipment was attached to the roofs trusses inside the cold attic in order to measure moisture ratio in these, relative air humidity and temperature in the surroundings of the trusses. A weather station was set up in the closeness of the house in purpose to be able to compare weather data to the data recorded by the measuring equipment in the attic. The weather station measured temperature, relative air humidity, precipitation, wind speed and wind direction from the outdoor climate. The second method was based on performing a thermal and humidity simulation using WUFI. In the program a simulation of the cold attic was performed. The simulation presented moisture data during the same interval as the field study and for the further five years to come. Measured data from measuring equipment, weather station and WUFI was compiled in order to be analyzed using produced, critical values for mold growth. Factors of values which was used for performing the analysis and the final evaluation was following: Relative air humidity, temperature and moisture ratio in the wood of the roofs trusses. The study showed that the cold attic does not make a risk for being exposed to issues regarding mold growth thus reign of critical values during some of the periods of the interval. The outdoor climate indicated to have a controlling effect on the climate in the attic. The relative air humidity in the attic rises when precipitation occurs and also when powerful, southwestern and southern winds reigns. The relative air humidity in the attic increases substantially when precipitation occurs in combination with southern winds. As precipitation occurs in itself, the temperature drops in the attic. Temperature in the attic does not show any noticeable connection to wind direction or speed. The roof trusses moisture ratio increases during periods of precipitation and also when southern or northern winds reigns. Wind speed does not show any noticeable connection with how the moisture ratio differs. The relative air humidity in the cold attic has a close resemblance to the relative air humidity outside. The temperature in the cold attic has a close resemblance to the temperature outside. Moisture ratio in the roof trusses does not show any noticeable connection to relative air humidity and temperature outside. / Fuktproblem är bland de vanligaste problemen som ett hus kan utsättas för. Problem i form av fukt leder ofta till skador eller tillväxt av oönskade mikroorganismer i husets konstruktion. Hus som drabbats av problem i samband med fukt kan ha en negativ inverkan på inomhusmiljön och hälsan för de människor som vistas i husen samt försämra konstruktionens hållfasthet. Enligt en undersökning publicerad av Boverket år 2010 är cirka 36 % av alla byggnader i Sverige utsatta för fukt- och mögelskador, flest skador påvisas i småhus. I småhusen är takets vindsutrymme den mest utsatta delen. Åtgärdskostnaden för fuktskadorna i drabbade småhus uppskattas till en kostnad om 91,2 miljarder kronor. Uppkomsten av problemen beror på många olika faktorer. Väder och klimat är av stor betydelse för hur ett hus utsätts för oönskad fukt. Nederbörd, luftfuktighet, temperatur, vindhastighet och vindriktning är några faktorer som är bidragande. Idag finns ett stort fokus på att bygga energisnåla hus medfört av allt hårdare krav om energiförbrukning. Sektorn för bostäder och service står för upp till 40 % av Sveriges totala energianvändning. I frågan om mer energisnåla byggnationer har nya idéer växt fram under åren, och ett typiskt exempel är lågenergihus. Lågenergihus är projekterade som täta och välisolerade hus i syfte att minska husets svinn av värmeenergi och därmed minskad energiåtgång för att vara i drift. Det debatteras flitigt om lågenergihus löper större risk att drabbas av fuktproblem än traditionella hus på grund av konstruktionens täthet och större mängd värmeisolering. Teoretiskt sett löper lågenergihus en större risk för att drabbas av fuktproblem i form av mikrobiell tillväxt men beroende på utformning och med hjälp av kunskap kan problemen undvikas. Kallvindar utgör ett vindsutrymme där klimatet i utrymmet liknar klimatet utomhus. Tidigare studier visar en trend att kallvindar har en ökad risk att utsättas för mögelsvamp på grund av fuktproblem. Ett lågenergihus med kallvind bör, enligt ovanstående, utgöra en stor risk att drabbas av fuktproblem. I denna studie har en fuktanalys genomförts av en kallvind i ett lågenergihus. Huset är placerat i Molkom, Värmland, och är relativt nybyggt. Målet med analysen var att undersöka om delar i kallvinden löpte risk att drabbas av fuktproblem i form av påväxt av mikroorganismer i relation till vädrets faktorer. Analysen utgjorde två separata metoder: en praktisk mätstudie där fuktmätare fästs i takstolarna inom kallvinden för att mäta fukthalt i takstolarna samt relativ luftfuktighet och temperatur i dess omgivning. I husets närhet placerades en väderstation i syfte att jämföra väderdata med data från mätare placerade i vindsutrymmet och hur vädret påverkar klimatet i vindsutrymmet. Väderstationen gav data för temperatur, luftfuktighet, nederbörd, vindhastighet och vindriktning utomhus. Den andre metoden var att utföra en värme- och fuktsimulering i programmet WUFI. I programmet genomfördes en simulering av kallvinden. Simuleringen presenterade fuktdata under samma tid som den praktiska studien avsett samt under kommande 5 år. Uppmätt data från mätare, väderstation och WUFI sammanställdes för att analyseras utifrån framtagna kritiska värden för mikrobiell tillväxt. Värden för faktorer som beaktades för att genomföra analysen och den slutliga bedömningen var: relativ luftfuktighet, temperatur och fukthalt i material. Ur studien framgår det att kallvinden inte utgör någon risk att drabbas av problem i samband med mögelsvampstillväxt trots kritiska värden under vissa perioder. Vädret visade sig att ha en stor inverkan på klimatet i vindsutrymmet. Den relativa luftfuktigheten i vindsutrymmet ökar då nederbörd förekommer samt när kraftiga, sydvästliga och sydliga vindar råder. Den relativa luftfuktigheten i vindsutrymmet ökar väsentligt då nederbörd sker i kombination med sydliga vindar. Då nederbörd förekommer sjunker temperaturen i vindsutrymmet. Temperaturen i vindsutrymmet visar inga tydliga samband med vindens riktning eller hastighet Fukthalten i takstolsvirket i vindsutrymmet ökar under nederbördsperioder samt när sydliga eller nordliga vindar råder. Vindens hastighet visar ingen påverkan för fukthalten. Den relativa luftfuktigheten i vindsutrymmet liknar den relativa luftfuktigheten utomhus. Temperaturen i vindsutrymmet liknar den temperatur som råder utomhus. Fukthalten i takstolarnas virke förhåller sig inte tydligt i samband med relativ fuktighet och temperatur utomhus.
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End-to-end Security Enhancement of an IoT Platform Using Object SecurityTjäder, Hampus January 2017 (has links)
The Internet of Things (IoT) is seen as one of the next Internet revolutions. In a near future the majority of all connected devices to the Internet will be IoT devices. These devices will connect previously offline constrained systems, thus it is essential to ensure end-to-end security for such devices. Object Security is a concept where the actual packet or sensitive parts of the packet are encrypted instead of the radio channel. A compromised node in the network will with this mechanism still have the data encrypted ensuring full end-to-end security. This paper proposes an architecture for using the object security format COSE in a typical constrained short-range radio based IoT platform. The IoT platform utilizes Bluetooth Low Energy and the Constrained Application Protocol for data transmission via a capillary gateway. A proof-of-concept implementation based on the architecture validates that the security solution is implementable. An overhead comparison between current channel security guidelines and the proposed object security solution results in a similar size for each data packet. The thesis concludes that object security should be seen as an alternative for ensuring end-to-end security for the Internet of Things.
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Nízkoenergetické stavby v České republice / Low-energy houses in Czech RepublicSvobodová, Jana January 2008 (has links)
The main goal of the thesis is building up low-energy houses in the Czech Republic, especially family houses. In my thesis, I describe the history of low-energy development in the Czech Republic, a possible future and some foreign experience. I compare the standard version of development, which is demanded by Czech laws, with the low-energy version by means of SWOT and financial analysis. I try to define a life cycle assessment of a building, its environmental impact during its construction and usage by means of LCA method. Based on the findings of LCA method I would like to draw attention to the necessity to focus more on the low-energy development. The results of financial analysis shows that it is necessary to implement some instruments of environmental policy in order to support the low-energy development and project, such as tax preferences for low-energy development etc.
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Etude expérimentale et numérique du traitement des ambiances par le vecteur air dans les bâtiments à très basse consommation d'énergie / Experimental and numerical study of ventilative heating and cooling in low-energy buildingsCablé, Axel 19 April 2013 (has links)
Les bâtiments à très basse consommation d’énergie bénéficient d’une isolation thermique performante et d’une bonne étanchéité à l’air, souvent couplées à une conception bioclimatique du bâtiment. L’apport d’énergie nécessaire au chauffage et au rafraîchissement de l’ambiance s’en trouve considérablement réduit. Dans ce contexte, il devient possible d’utiliser l’air comme unique vecteur d’énergie, à des débits suffisamment faibles pour permettre son intégration dans le système de ventilation sanitaire, et avec un écart de température réduit entre l’air soufflé et l’ambiance. Une unité terminale de soufflage, ou diffuseur d’air, a alors pour rôle d’assurer un mélange optimal de l’air neuf avec l’air ambiant, de façon à obtenir une répartition homogène de température et de vitesse dans les pièces d’habitation, et un bon renouvellement de l’air intérieur. Ce travail de thèse propose une étude du confort thermique et de l’efficacité de ventilation dans une cellule climatique à échelle 1 en conditions contrôlées, dans le contexte d’utilisation d’un système combiné de ventilation, chauffage et rafraîchissement. Une stratégie de ventilation par mélange est mise en œuvre à l’aide d’un diffuseur d’air composé de douze buses lobées de géométrie complexe, et l’occupation est prise en compte par des mannequins cylindriques, qui constituent des sources de chaleur sensible et de dioxyde de carbone. La vitesse d’air, la concentration en CO2 ainsi que les températures d’air, de globe noir et des parois de la cellule sont suivies expérimentalement pour différentes conditions de soufflage d’air chaud et froid. Les mesures expérimentales sont complétées par des simulations numériques de mécanique des fluides (CFD), qui visent à caractériser l’écoulement dans la cellule. Cette approche fait intervenir une méthode de modélisation en deux temps afin d’intégrer correctement la géométrie complexe du diffuseur d’air dans les simulations. Des études paramétriques sont ensuite proposées pour des conditions non testées expérimentalement. Celles-ci visent à mettre en évidence l’impact des conditions de soufflage et des charges internes sur l’écoulement et sur le confort, pour les conditions spécifiques aux bâtiments à très basse consommation d’énergie. / Low-energy buildings benefit from a good thermal insulation and air tightness, associated with a smart integration of the building in its environment. Consequently, the required power for heating and cooling of the building is reduced to a great extent. This allows the use of conditioned ventilation air as the only energy vector: the air is supplied into the rooms at a low-velocity and with a low temperature difference with the indoor air. Air terminal devices are used, whose aim is to provide a homogeneous distribution of temperature and velocity inside of the rooms, and an efficient disposal of the indoor air pollutants. In this prospect, the thermal comfort and ventilation effectiveness in a test room (scale 1) resulting from an integrated heating, cooling and ventilation system is assessed both experimentally and numerically. The air is supplied close to the ceiling through a wall-mounted diffuser of complex geometry composed of twelve lobed nozzles, and the occupancy is modeled by two cylindrical manikins releasing sensible heat and carbon dioxide. Experimentally, the air velocity, CO2 concentration, indoor air, wall and black globe temperatures are monitored in order to assess the Predicted Mean Vote and draught rate in the occupied zone as well as the ventilation efficiency. Computational Fluid Dynamics (CFD) simulations are then performed in order to provide valuable information on the airflow patterns in the room. The air diffuser’s geometry being too complex for a direct simulation, a two-step modeling approach is adopted in order to take it into account in the simulations and to accurately represent the heat and mass transfers in the room. Furthermore, parametric studies are performed in order to investigate the influence of the supplying conditions and the internal heat gains on the airflow and on the resulting comfort, for particular conditions corresponding to those of low-energy buildings.
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Fotobiomodulação comparativa entre o laser e LED de baixa intensidade na angiogênese de feridas cutâneas de ratos / Comparative fotobiomodulation between the LED and low intensity laser in the angiogenisis of skin wounds in ratsAdalberto Vieira Corazza 12 December 2005 (has links)
Os diodos emissores de luz Light Emitting Diodes (LEDs) são uma fonte de luz que estão sendo introduzidas comercialmente, mas com discreta base científica nesta modalidade fototerapêutica. O presente estudo comparou os efeitos angiogênicos da luz laser coerente e colimada à luz LED ausente de coerência e colimação em feridas induzidas em ratos, com fluências diferentes. O modelo experimental consistia da indução de uma ferida circular no quadríceps de 120 ratos, utilizando um punch com 15 mm de diâmetro. Os animais foram divididos aleatoriamente em 5 grupos: laser (660 nm) e LED (635 nm), sendo cada um ajustado a 5 J/'CM POT.2' e 20 J/'CM POT.2', além do controle. Após 6 horas da indução das feridas, os grupos tratados recebiam aplicação pontual de contato, e irradiados a cada 24 horas. A angiogênese foi analisada por meio da histomorfometria (H.E), e a contração das feridas pelo software de planimetria, sendo estudados os resultados no 3º, 7º, 14º e 21º dias pós-lesão. Os achados da análise histológica no 3º dia foram determinantes para induzir uma grande eficiência na proliferação de vasos sanguíneos dos grupos tratados em relação ao controle, demonstrando uma taxa próxima da constante no 7º dia, e com discreto aumento no 14º dia, porém com destaque para a tecnologia LED a 5 J/'CM POT.2' (p '< OU =' 0,05). No 21º dia, os grupos fototratados com fluência de 5 J/'CM POT.2' apresentavam valores estatísticos com maior eficiência na angiogênese quando comparados com o grupo laser a 20 J/'CM POT.2, sugerindo que fluências elevadas podem induzir um processo do tipo saturação. Não ocorreu diferença da neovascularização no centro e nas margens da ferida (p '< OU =' 0,05), sugerindo que ocorria uma fotobiomodulação de toda a lesão, favorecendo o crescimento homogêneo dos vasos sanguíneos. Tanto o laser quanto o LED não apresentaram resultados significativos na redução da área das feridas. As fototerapias a laser e LED de baixa intensidade sugeriram que a coerência e a colimação não eram fatores decisivos para induzir alterações nas funções celulares, e sim a banda de absorção do espectro eletromagnético. Ambas as fontes de luz vermelha ajustadas a fluências de 5 J/'CM POT.2' podem demonstrar resultados expressivos no estímulo angiogênico em pele lesada / The light emitting diodes (LEDs) are a source of light that have been commercially introduced, but still with a lack in its scientific basis in this phototherapeutic modality. The present study compared the angiogenics effects of the laser and LED illumination in induced wounds in rat, with fluencies different. The experimental model consisted of the induction of a circular wound on the quadriceps of 120 rats, using a punch with 15 mm diameter. Animals were divided randomyzed in 5 groups: laser and LED each device with a dosage of 5 J/'CM POT.2' and 20 J/'CM POT.2', and control. After 6 hours of the induction of the wounds, the treated groups received contact of punctual application, and irradiated every 24 hours. The angiogenesis was studied through the histomorphometric (H.E) and the wounds contraction was photographed and analyzed in the planimetrical software in the 3rd, 7th, 14th and 21st lesion induced days. The discoveries of the histological analysis in the 3rd day revealed larger efficiency in the proliferation of the blood vessels in all irradiated groups in comparison to controls, being a rate near of the constant in the 7th day, following to discreet improves in the 14th, even so with prominence for the LED with 5 J/'CM POT.2'. In the 21st day, the groups phototreatment with fluence of 5 J/'CM POT.2' showed similar statistically values in the larger efficiency in the angiogenesis, when to compare to laser with 20 J/'CM POT.2', suggesting high fluencies can induced a saturation process. The average of the area reduction of the wound didn't present similar statistician values of the treated groups in relation to the control (p '< OU =' 0,05). The phototherapeutic laser and LEDs of low intensity they suggested that the coherence and the collimation were not decisive factors to induce alterations in the cellular functions, but the band of the spectrum electromagnetic. The both red source of light agreements to fluencies of the 5 J/'CM POT.2', they can demonstrate expressive results in the incentive ulcerated skin angiogenic
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Development of new dosimetric standards for low energy X-rays (≤ 50 keV) used in contact radiotherapy / Développement d’une référence métrologique pour les faisceaux X de basse énergie utilisés en radiothérapie de contactAbudra'a, Abdullah 11 December 2017 (has links)
La curiethérapie électronique, également appelée radiothérapie de contact, est une technique de traitement du cancer utilisant des rayons X de faible énergie (≤ 50 keV) générés par des tubes à rayons X miniaturisés et positionnés au contact des tissus à irradier. La miniaturisation des générateurs à rayons X a conduit au développement de nouveaux systèmes de traitement, dont le plus répandu dans le monde et le seul utilisé en France est le système INTRABEAM® commercialisé par la société Zeiss. Au-delà du bénéfice médical, les avantages potentiels de la curiethérapie électronique sont une diminution drastique de l'inconfort du patient combinée à un moindre coût de traitement. Ainsi, dans le cadre du cancer du sein qui correspond à l’application principale de l’INTRABEAM, cette technique remplace la trentaine de séances de radiothérapie externe classiquement prescrite suite à l’exérèse du volume tumoral par une seule et unique séance délivrée en 20 à 50 minutes au bloc opératoire directement après l’acte chirurgical alors que la patiente est encore sous anesthésie. Cette radiothérapie peropératoire (RTPO) associe au mini générateur de rayons X des applicateurs qui, en sénologie, correspondent à des sphères de différents diamètres conçues pour épouser au mieux la cavité tumorale résultant de l’exérèse. La dose délivrée en RTPO est classiquement de l'ordre de 20 Gy en surface du lit tumoral et diminue rapidement avec la profondeur afin de préserver les tissus sains voisins (< 1 Gy après quelques cm). En France, le 1er traitement par RTPO a eu lieu à Nantes fin 2011. Aujourd’hui, une dizaine de centres hospitaliers français propose des traitements par RTPO au moyen de la technique INTRABEAM®. Très rapidement, plusieurs physiciens médicaux ont exprimé au laboratoire français de métrologie de la dose (LNHB), leur besoin de raccordement dosimétrique à une référence indépendante du constructeur. Ce besoin a été réaffirmé par la Haute Autorité de Santé (HAS) dans un rapport sur l’évaluation de la RTPO dans le cancer du sein, édité en avril 2016. Le présent travail vise à renforcer la sécurité d’emploi d’appareils de RTPO par rayons X de basse énergie (< 50 keV). Cependant, afin de répondre aux physiciens médicaux français et du fait de contraintes temporelles, l’étude est ici limitée au système INTRABEAM associé au seul applicateur sphérique de 4 cm de diamètre. Le travail a été articulé autour de trois axes. Le premier a concerné l’établissement et le transfert d’une référence primaire en termes de dose absorbée dans l’eau à 1 cm de profondeur. La méthodologie a été développée et ensuite appliquée pour le système INTRABEAM® associé à un applicateur sphérique de 4 cm, pour lequel, la référence primaire a été réalisée. Le deuxième axe a eu pour objet la détermination de la distribution spatiale de dose autour de la source considérée par l’utilisation de gels dosimétriques et par calcul de type Monte Carlo. L’hydrogel à base de Fricke, utilisé ici, est lu par imagerie par résonance magnétique à l’hôpital d’Orsay. Ce gel a été étalonné en dose pour des photons d’énergie inférieure à 50 keV puis utilisé pour déterminer les profils de doses autour de la source INTRABEAM® associée à l’applicateur sphérique de 4 cm de diamètre dans les plans axial et transverse incluant le centre de la source INTRABEAM®. Quant au dernier axe, il s’est agi de confronter des données dosimétriques fournies par la société Zeiss, concernant l’INTRABEAM® en utilisation à l’hôpital St-Louis à Paris, à celles obtenues au cours de la présente étude pour le même système. Des différences significatives ont été trouvées entre les doses délivrées par Zeiss et celles obtenues dans la présente étude. Une étude indépendante menée par le PTB pour une autre configuration de source INTRABEAM® a conduit à des observations comparables. L’approche adoptée par Zeiss a ainsi été investiguée dans le présent travail et une cause de divergence a été proposée. / Electronic Brachytherapy (eBT), also called contact radiotherapy, is a cancer treatment technique using low energy X-Rays (≤ 50 keV) generated by X-Ray tubes which are placed in close contact with the treated lesions. The latest evolutions of miniaturized X-Ray tubes led to the development of new treatment systems, such as the INTRABEAM® system of the ZEISS Company which is the most available eBT system and the only one currently used in France. Beside its medical benefit, the potential major advantages of treatment by eBT are the drastic decrease in patient discomfort and treatment cost. In the case of breast cancer treatment with such technique, the treatment is given in a single session that lasts 20 to 50 minutes where a high dose, in the order of 20 Gy, is delivered to the tumor bed surface in contact with spherical applicators associated to the X-Ray source. The delivered dose decreases rapidly with depth (< 1 Gy after a few centimeters) enabling to preserve neighboring healthy tissues. In France, the first IORT treatment performed was in Nantes in 2011. Today, ten medical centers offer IORT treatment using the INTRABEAM® system. Consequently, several medical physicists addressed to the French national metrology laboratory for ionizing radiation (LNHB) their need for a dosimetric traceability with a reference independent from the manufacturer. This need was reaffirmed by the French Authority for Health (HAS), in their report on the evaluation of the IORT for breast cancer treatment published in April 2016. This thesis work is a contribution to the metrological work initiated by LNHB for enhancing the safety of employing IORT by eBT systems. It was limited, within the thesis period, to the INTRABEAM® system associated with a 4 cm diameter spherical applicator. The thesis work was oriented towards three main objectives. The first one concerned the establishment and the transfer of a primary dosimetric standard, in terms of absorbed dose to water at 1 cm depth in water. The methodology was developed and applied on the INTRABEAM® system with 4 cm spherical applicator, for which, the dosimetric reference was established. The second objective was to use a dosimetric gel and the Monte Carlo method to assess the 3D spatial distribution of the relative absorbed dose delivered by such a system. The dosimetric gel system used was a Fricke-based hydrogel read by Magnetic Resonance Imaging at Service Hospitalier Frédéric Joliot in Orsay (SHFJ). The gel reading was calibrated, in terms of absorbed dose for low energy X-Rays (< 50 keV), and then used to define the relative dose distributions of the INTRABEAM® X-Ray source associated with the 4 cm spherical applicator in the axial and transverse planes of the X-Ray source probe tip. The last objective was to compare the dosimetric data delivered by Zeiss, for the INTRABEAM® system used at St. Louis hospital in Paris, by the ones obtained in the current study for the same system. Significant discrepancies were found from this comparison between the doses delivered by Zeiss and those obtained in the current study. Discrepancies were also observed in a separate work conducted by the PTB under a different INTRABEAM® configuration. Some reasons of these discrepancies are outlined and discussed in this study.
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Design and prototyping of indoor positioning systems for Internet-of-Things sensor networksShakoori Moghadam Monfared, Shaghayegh 04 January 2021 (has links) (PDF)
Accurate indoor positioning of narrowband Internet-of-Things (IoT) sensors has drawn more attention in recent years. The introduction of Bluetooth Low Energy (BLE) technology is one of the latest developments of IoT and especially applicable for Ultra-Low Power (ULP) applications. BLE is an attractive technology for indoor positioning systems because of its low-cost deployment and reasonable accuracy. Efficient indoor positioning can be achieved by deducing the sensor position from the estimated signal Angle-of-Arrival (AoA) at multiple anchors. An anchor is a base station of known position and equipped with a narrowband multi-antenna array. However, the design and implementation of indoor positioning systems based on AoA measurements involve multiple challenges. The first part of this thesis mainly addresses the impact of hardware impairments on the accuracy of AoA measurements. In practice, the subspace-based algorithms such as Multiple Signal Classification (MUSIC) suffer from sensitivity to array calibration errors coming from hardware imperfections. A detailed experimental implementation is performed using a Software Defined Radio (SDR) platform to precisely evaluate the accuracy of AoA measurements. For this purpose, a new Over-the-Air (OTA) calibration method is proposed and the array calibration error is investigated. The experimental results are compared with the theoretical analysis. These results show that array calibration errors can cause some degrees of uncertainty in AoA estimation. Moreover, we propose iterative positioning algorithms based on AoA measurements for low capacity IoT sensors with high accuracy and fair computational complexity. Efficient positioning accuracy is obtained by iterating between the angle and position estimation steps. We first develop a Data-Aided Maximum a Posteriori (DA- MAP) estimator based on the preamble of the transmitted signal. DA-MAP estimator relies on the knowledge of the transmitted signal which makes it impractical for narrowband communications where the preamble is short. For this reason, a Non-Data- Aided Maximum a Posteriori (NDA-MAP) estimator is developed to improve the AoA accuracy. The iterative positioning algorithms are therefore classified as Data-Aided Iterative (DA-It) and Non-Data-Aided Iterative (NDA-It) depending on the knowledge of the transmitted signal that is used for estimation. Both numerical and experimental analyses are carried out to evaluate the performance of the proposed algorithms. The results show that DA-MAP and NDA-MAP estimators are more accurate than MUSIC. The results also show that DA-It comes very close to the performance of the optimal approach that directly estimates the position based on the observation of the received signal, known as Direct Position Estimation (DPE). Furthermore, the NDA-It algorithm significantly outperforms the DA-It because it can use a much higher number of samples; however, it needs more iterations to converge. In addition, we evaluate the computational savings achieved by the iterative schemes compared to DPE through a detailed complexity analysis. Finally, we investigate the performance degradation of the proposed iterative algorithms due to the impact of multipath and NLOS propagation in indoor environments. Therefore, we develop an enhanced iterative positioning algorithm with an anchor selection method in order to identify and exclude NLOS anchors. The numerical results show that applying the anchor selection strategy significantly improves the positioning accuracy in indoor environments. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
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Atomic Layer Deposition of H-BN(0001) on Transition Metal Substrates, and In Situ XPS Study of Carbonate Removal from Lithium Garnet SurfacesJones, Jessica C. 05 1900 (has links)
The direct epitaxial growth of multilayer BN by atomic layer deposition is of critical significance forfo two-dimensional device applications. X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) demonstrate layer-by-layer BN epitaxy on two different substrates. One substrate was a monolayer of RuO2(110) formed on a Ru(0001) substrate, the other was an atomically clean Ni(111) single crystal. Growth was accomplished atomic layer deposition (ALD) cycles of BCl3/NH3 at 600 K substrate temperature and subsequent annealing in ultrahigh vacuum (UHV). This yielded stoichiometric BN layers, and an average BN film thickness linearly proportional to the number of BCl3/NH3 cycles. The BN(0001)/RuO2(110) interface had negligible charge transfer or band bending as indicated by XPS and LEED data indicate a 30° rotation between the coincident BN and oxide lattices. The atomic layer epitaxy of BN on an oxide surface suggests new routes to the direct growth and integration of graphene and BN with industrially important substrates, including Si(100). XPS and LEED indicated epitaxial deposition of h-BN(0001) on the Ni(111) single crystal by ALD, and subsequent epitaxially aligned graphene was deposited by chemical vapor deposition (CVD) of ethylene at 1000 K. Direct multilayer, in situ growth of h-BN on magnetic substrates such as Ni is important for spintronic device applications. Solid-state electrolytes (SSEs) are of significant interest for their promise as lithium-ion conducting materials but are prone to degradation due to lithium carbonate formation on the surface upon exposure to atmosphere, adversely impacting Li ion conduction. In situ XPS monitored changes in the composition of the SSE Li garnet (Li6.5La3Zr1.5Ta0.5O12, LLZTaO) upon annealing in UHV and upon Ar+ ion sputtering. Trends in core level spectra demonstrate that binding energy (BE) calibration of the Li 1s at 56.4 eV, yields a more consistent interpretation of results than the more commonly used standard of the adventitious C 1s at 284.8 eV. Annealing one ambient-exposed sample to >1000 K in UHV effectively reduced surface carbonate and oxygen, leaving significant amounts of carbon in lower oxidation states. A second ambient-exposed sample was subjected to 3 keV Ar+ ion sputtering at 500 K in UHV, which eliminated all surface carbon, and reduced the O 1s intensity and BE. These methods present alternative approaches to lithium carbonate removal than heating or polishing in inert atmospheres and are compatible with fundamental surface science studies. In particular, the data show that sputtering at mildly elevated temperatures yields facile elimination of carbonate and other forms of surface carbon. This is in contrast to annealing in either UHV or in noble gas environments, which result in carbonate reduction, but with significant remnant coverages of other forms of carbon.
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