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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 11 to 18 of 18 (0.017 seconds)| 11 |
Chemistry in the Final Stages of Stellar Evolution: Millimeter and Submillimeter Observations of Supergiants and Planetary NebulaeEdwards, Jessica Louise January 2015 (has links)
High mass loss rates in evolved stars make them the major contributors to recycling processed material back into the interstellar medium. This mass loss creates large circumstellar shells, rich in molecular material. This dissertation presents millimeter and submillimeter studies of the end stages of low mass and high mass stars in order to probe their molecular content in more detail. In low mass stars, the molecular material is carried on into the planetary nebula (PN) stage. Observations of CS, HCO⁺, and CO in planetary nebulae (PNe) of various post-asymptotic giant branch ages have shown that molecular abundances in these objects do not significantly vary with age, as previously thought. More detailed observations of the slightly oxygen-rich PN NGC 6537 resulted in the detection of CN, HCN, HNC, CCH, CS, SO, H₂CO, HCO⁺ and N₂H⁺, as well as numerous ¹³C isotopologues. Observations of the middle-aged PN M2-48 showed the presence of CN, HCN, HNC, CS, SO, SO₂, SiO, HCO⁺, N₂H⁺, and several ¹³C isotopologues. These observations represent the first detections of CS, SO, SO₂, and SiO in any planetary nebula. The implications of these observations are discussed. A 1 mm spectral survey of the supergiant star NML Cygni has been carried out with the Arizona Radio Observatory Submillimeter Telescope resulting in the observation of 102 emission features arising from 17 different molecules and 4 unidentified features. The line profiles observed in this circumstellar shell are asymmetric and vary between different molecules, akin to what has been seen in another supergiant, VY Canis Majoris. The non-LTE radiative transfer code ESCAPADE has been used to model molecular abundances in the various asymmetric outflows of VY Canis Majoris, showing just how chemically and kinematically complex these supergiant circumstellar envelopes really are.
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Contribution à l'étude expérimentale et numérique du comportement hyperélastique et anisotrope de la peau humaine / Contribution to the experimental and numerical study of rhe anisotropic hyperelastic behavior of the human skinRemache, Djamel 13 December 2013 (has links)
D’un point de vue mécanique, la peau est une structure multicouche complexeayant des propriétés viscoélastique, non-linéaire, quasi-incompressible, anisotrope eten état de précontrainte. Le travail présenté dans cette thèse associe expérimentation,modélisation et identification numérique et se distingue en particulier parl’utilisation d’un dispositif d’extensométrie développé au laboratoire et adapté à desmesures in vivo non invasives. Des tests ex vivo ont cependant été réalisés égalementà titre de comparaison et de validation. Une attention particulière a été portée à latension cutanée initiale (ou naturelle). Les essais in vivo ont permis d’obtenir desréponses force – déplacement sous différentes configurations angulaires, d’intensitéet pour diverses localisations corporelles. Les essais ex vivo ont quant à eux permisd’estimer l’état de contrainte initiale par la mesure des forces nécessaires à la remiseen tension d’explants. Ces différents essais expérimentaux ont été modélisés en utilisantdeux lois de comportement : la loi d’Ogden du premier ordre permettant dedécrire un comportement hyperélastique isotrope et la loi d’Holzapfel-Gasser-Ogden(HGO) décrivant un comportement hyper élastique anisotrope. Cette dernière a étéimplémentée sous l’interface utilisateur du logiciel ANSYS. Les paramètres caractéristiquesdes zones cutanées testées ont été identifiés par méthode inverse. L’influencede la compressibilité de la peau sur son comportement mécanique est mise en évidence.Au final, les travaux de cette thèse ont été appliqués au lambeau d’avancementde type V-Y qui est une technique de suture pratiquée pour combler les pertes desubstance.229 / From a mechanical point of view, the human skin is a complex multilayerstructure with viscoelastic, non-linear and anisotropic properties and a pre-stressstate. The work presented in this thesis combines experimentation, modeling andnumerical identification and distinguishes especially by the use of an extensometerdevice developed in the laboratory and suitable for non-invasive in vivo measurements.Ex vivo tests were however also performed for comparison and validation.Particular attention was paid to the initial skin tension. in vivo tests allowed theobtaining of load – displacement responses for different angular configurations, intensitiesand body locations. ex vivo tests in turn allowed the estimation of the stateof initial stress by measuring the forces necessary for the re-tension of the explants.These different experimental tests were modeled using two constitutive laws : thefirst order Ogden law allowing the description of an isotropic hyperelastic behavior,and the Holzapfel-Gasser-Ogden’ law (HGO) allowing the description of an anisotropichyperelastic behavior. The latter was implemented in the user interface ofANSYS software. The characteristics parameters of the skin areas tested were identifiedby the reverse method. The influence of the compressibility of the skin on itsmechanical behavior is highlighted. Finally, the work of this thesis were applied toan advancement flap of V-Y type.
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Bitech. Ett front-end-projekt : En digital lösning för byggarbetsplatsen. / Bitech. A front-end project : A digital solution for the construction site.Mineur, Olle, Gong, Hemming, Gustavsson, Emelie, Holmegren, Sabrina, Ibrahim, Ramon, Kharaghani, Shayan, Palmér, Mervan, Wilnerzon, Roberto January 2024 (has links)
Den här rapporten beskriver resultaten och metodologierna för Bitech front-end-projektet, ett omfattande mjukvaruutvecklingsinitiativ som syftar till att digitalisera och effektivisera verksamheten på byggarbetsplatser. Projektet använder avancerade webbteknologier för att skapa användarvänliga, dynamiska och responsiva gränssnitt som är lämpliga för både platsbaserade och administrativa behov inom byggbranschen. Viktiga aspekter av projektet inkluderar integration av hantering av realtidsdata, mobilkompatibilitet för att säkerställa åtkomst på olika enheter, och robusta säkerhetsåtgärder för att skydda känslig projektdata. Under hela utvecklingsprocessen antog teamet agila metoder, med betoning på iterativ utveckling, kontinuerlig testning och regelbunden kundfeedback, vilket underlättade en flexibel och responsiv utvecklingsmiljö. Denna rapport ger en detaljerad analys av projektets utfall, lärdomar och rekommendationer för framtida initiativ som syftar till att öka den teknologiska adoptionen inom byggindustrin.
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Secure and Private Mobile Crowd Sensing for Street View / Säker och privat mobil Crowd Sensing för Street ViewZhang, Xiuqi January 2022 (has links)
Street View är en populär tjänst som ger mer information än traditionella karttjänster, men den ger också upphov till problem med integriteten. Populära kommersiella street view-tjänster misslyckas vanligtvis med att fullt ut skydda privatlivet för de personer som syns på bilderna. Ingen av dem tar heller hänsyn till integriteten för användare som laddar upp bilder. Å andra sidan är den nuvarande forskningen om preferenser för personlig integritet främst inriktad på sociala nätverk och ansiktsigenkänning. I och med utvecklingen av Mobile Crowd Sensing föreslår vi en tjänst för gatuvyer som bygger på frivilliga bidrag och som skyddar båda: anonymitet för användare som laddar upp bilder, och anonymitet och maximal integritet i verkliga livet för användare/egendomar i bilderna. Detta projekt bygger en säker och privat gatuvy som är mobilt användarvänlig och håller tillgänglighet. / Street View is a popular service providing additional information to traditional map services, but it also raises privacy concerns. Popular commercial street view services usually fail to fully protect the privacy of people in the pictures. In addition, none of them concerns the privacy of users who upload pictures. On the other hand, current research about privacy preferences mainly focuses on social networks and facial recognition. With the development of Mobile Crowd Sensing, we propose a Street View service based on volunteer contributions that protect both: anonymity of users who uploads pictures, and anonymity and maximum real-life privacy of user/properties in pictures. This project builds a secure and private street view which is mobile device friendly and keeps availability.
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Credit Risk Modeling And Credit Default Swap Pricing Under Variance Gamma ProcessAnar, Hatice 01 August 2008 (has links) (PDF)
In this thesis, the structural model in credit risk and the credit derivatives is studied under both Black-Scholes setting and Variance Gamma (VG) setting. Using a Variance Gamma process, the distribution of the firm value process becomes asymmetric and leptokurtic. Also, the jump structure of VG processes
allows random default times of the reference entities. Among structural models, the most emphasis is made on the Black-Cox model by building a relation between the survival probabilities of the Black-Cox model and the value of a binary down and out barrier option. The survival probabilities under VG setting are
calculated via a Partial Integro Differential Equation (PIDE). Some applications of binary down and out barrier options, default probabilities and Credit Default Swap par spreads are also illustrated in this study.
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Completion, Pricing And Calibration In A Levy Market ModelYilmaz, Busra Zeynep 01 September 2010 (has links) (PDF)
In this thesis, modelling with Lé / vy processes is considered in three parts. In the first part, the general geometric Lé / vy market model is examined in detail. As such markets are generally incomplete, it is shown that the market can be completed by enlarging with a series of new artificial assets called &ldquo / power-jump assets&rdquo / based on the power-jump processes of the underlying Lé / vy process. The second part of the thesis presents two different methods for pricing European options: the martingale pricing approach and the Fourier-based characteristic formula method which is performed via fast Fourier transform (FFT). Performance comparison of the pricing methods led to the fact that the fast Fourier transform produces very small pricing errors so the results of both methods are nearly identical. Throughout the pricing section jump sizes are assumed to have a particular distribution. The third part contributes to the empirical applications of Lé / vy processes. In this part, the stochastic volatility extension of the jump diffusion model is considered and calibration on Standard& / Poors (S& / P) 500 options data is executed for the jump-diffusion model, stochastic volatility jump-diffusion model of Bates and the Black-Scholes model. The model parameters are estimated by using an optimization algorithm. Next, the effect of additional stochastic volatility extension on explaining the implied volatility smile phenomenon is investigated and it is found that both jumps and stochastic volatility are required. Moreover, the data fitting performances of three models are compared and it is shown that stochastic volatility jump-diffusion model gives relatively better results.
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3D Video Playback : A modular cross-platform GPU-based approach for flexible multi-view 3D video renderingAndersson, Håkan January 2010 (has links)
The evolution of depth‐perception visualization technologies, emerging format standardization work and research within the field of multi‐view 3D video and imagery addresses the need for flexible 3D video visualization. The wide variety of available 3D‐display types and visualization techniques for multi‐view video, as well as the high throughput requirements for high definition video, addresses the need for a real‐time 3D video playback solution that takes advantage of hardware accelerated graphics, while providing a high degree of flexibility through format configuration and cross‐platform interoperability. A modular component based software solution based on FFmpeg for video demultiplexing and video decoding is proposed,using OpenGL and GLUT for hardware accelerated graphics and POSIX threads for increased CPU utilization. The solution has been verified to have sufficient throughput in order to display 1080p video at the native video frame rate on the experimental system, which is considered as a standard high‐end desktop PC only using commercial hardware. In order to evaluate the performance of the proposed solution a number of throughput evaluation metrics have been introduced measuring average frame rate as a function of: video bit rate, video resolution and number of views. The results obtained have indicated that the GPU constitutes the primary bottleneck in a multi‐view lenticular rendering system and that multi‐view rendering performance is degraded as the number of views is increased. This is a result of the current GPU square matrix texture cache architectures, resulting in texture lookup access times according to random memory access patterns when the number of views is high. The proposed solution has been identified in order to provide low CPU efficiency, i.e. low CPU hardware utilization and it is recommended to increase performance by investigating the gains of scalable multithreading techniques. It is also recommended to investigate the gains of introducing video frame buffering in video memory or to move more calculations to the CPU in order to increase GPU performance.
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Streamlining Certification Management with Automation and Certification Retrieval : System development using ABP Framework, Angular, and MongoDB / Effektivisering av certifikathantering med automatisering och certifikathämtning : Systemutveckling med ABP Framework, Angular och MongoDBHassan, Nour Al Dine January 2024 (has links)
This thesis examines the certification management challenge faced by Integrity360. The decentralized approach, characterized by manual processes and disparate data sources, leads to inefficient tracking of certification status and study progress. The main objective of this project was to construct a system that automates data retrieval, ensures a complete audit, and increases security and privacy. Leveraging the ASP.NET Boilerplate (ABP) framework, Angular, and MongoDB, an efficient and scalable system was designed, developed, and built based on DDD (domain-driven design) principles for a modular and maintainable architecture. The implemented system automates data retrieval from the Credly API, tracks exam information, manages exam vouchers, and implements a credible authentication system with role-based access control. With the time limitations behind the full-scale implementation of all the planned features, such as a dashboard with aggregated charts and automatic report generation, the platform significantly increases the efficiency and precision of employee certification management. Future work will include these advanced functionalities and integrations with external platforms to improve the system and increase its impact on operations in Integrity360.
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