Academic literature on the topic 'DFT/ DTFT'

This thesis examines the politics of the policy process concerning the introduction of digital terrestrial television (DTT) in Bulgaria. Bulgaria is an Eastern European post-communist country and a member of the European Union (EU) since 2007. The policy of digitalisation of terrestrial broadcasting is studied from a domestic perspective that focuses on the relevance of the national institutional structures and their response to internal and external (notably EU) influences. The thesis relies primarily on the ‘new institutionalist’ theoretical approach to examine how historical path dependencies and state capacities have enabled or disabled certain types of behaviour by public and private actors which have in turn shaped the policy process. In this respect, the role of the EU is seen as refracted through the prism of domestic arrangements, capacities and interests. The thesis demonstrates that the weak institutional capacities of the Bulgarian state, political patronage, clientelism and cronyism, failed to ensure a clear, fair and transparent DTT switchover policy. Sectoral broadcasting characteristics including the prominence of pay-for platforms and small market size contributed to this result, yet the thesis argues that the extent of their impact has been determined by structural characteristics within which the desion-making process has taken place. The thesis shows that far from genuine public interest objectives - such as increased media plurality, a stronger role for PSB, more competition within and between platforms, and efficient use of spectrum - the DTT transition in the country has served to reinforce path-dependencies and historical continuities. This last point has been observed in relation to digital television policies in Western countries, such as Britain and the USA (Galperin, 2004a) and Sweden and Spain (Suarez Cantel, 2011: 318). More research is needed to confirm or not this conclusion in relation to other (post-communist) countries and other sectors.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>The ultra high capacity disk-based data recorders now entering service offer not just a convenient and inexpensive alternative to conventional tape systems for applications like Telemetry and Flight Test but also a unique opportunity to rethink the classical models for data capture, analysis and storage. Based on ‘open architecture’ interface standards- typically SCSI-this new generation of products represents an entirely new approach to the way data is handled. But the techniques they employ are equally applicable to any SCSI storage device. This Paper discusses a range of practical scenarios illustrating how it is now possible to `mix-and-match’ recording technologies at will-disk-array, DLT, DTF, ExaByte, JAZ, ZIP, DVD, etc.- to produce an almost infinite combination of readily scaleable plug-and-play data capture, analysis and archiving solutions. The cost and reliability benefits arising from the use of standard mass-produced storage sub-systems are also considered

Sous irradiation, les flux de particules (neutrons, ions, électrons) créent des défauts ponctuels (lacunes et interstitiels) qui génèrent des défauts étendus (boucles de dislocation, cavités) responsables de la fragilisation des matériaux. L'aluminium est un matériau de faible masse et de faible énergie seuil de déplacement (Ed=16-19 eV) ce qui permet de créer les nanodéfauts étendus directement sous irradiation aux électrons dans un microscope électronique à transmission haute résolution (HRMET). Cet instrument permet non seulement de caractériser finement les nanodéfauts mais également d'étudier leur évolution in situ sous irradiation, ceci en fonction de la température, du taux de dommage et d'une pression partielle d'hydrogène. Nous avons constaté un effet important de la pression partielle d'hydrogène sur la cinétique de formation des boucles de dislocation et des cavités. Parallèlement, nous avons mis en place une modélisation multi-échelle des effets de taille finie et de discrétisation du réseau sur la morphologie d'équilibre des cavités à partir de calculs ab initio des énergies de surface et de liaison de petits amas lacunaires et des amas mixtes lacune-hydrogène. La caractérisation expérimentale des morphologies des cavités en fonction de leur taille met en évidence trois formes régulières : une forme de croix bordée par des surfaces {100}, une forme d'octaèdre non tronqué bordée par des surfaces {111} et une forme d'octaèdre tronqué, bordée par les surfaces {111} et {100} ainsi qu'un effet de taille finie entre ces formes prédit par le modèle. De même, la mesure des fluctuations morphologiques d'une cavité au cours de sa croissance ou de sa décroissance en taille révèle le rôle déterminant des nombres magiques fixés par la géométrie et la discrétisation du réseau. A partir du modèle thermodynamique des cavités et d'une caractérisation expérimentale de la densité volumique et de la distribution en taille des nanodéfauts, nous proposons un modèle de germination des cavités sous irradiation. Nous en déduisons une taille du germe critique et un taux de germination des cavités en fonction de la température et du taux de dommage, qui sont comparés aux valeurs expérimentales correspondantes extraites des observations in situ. Enfin, nous discutons de l'effet de l'hydrogène sur la stabilité des amas mixtes lacune-hydrogène et sur la cinétique de germination des cavités<br>Under irradiation, flows of particles (neutrons, ions, electrons) induce ponctual defects (vacancies and interstitials) which generate extended defects (dislocation loops, cavities) that are responsible for materials weakening. Aluminum is a low mass material with a low displacement energy (Ed=16-19 eV) which allows the creation of extended defects directly under electron irradiation in a high resolution transmission electron microscope (HRTEM). This instrument allows not only a fine characterization of nanodefects but also to study their evolution in situ under irradiation, depending on temperature, damage rate and a partial pressure of hydrogen. We noticed an important effect of the hydrogen partial pressure on the kinetic of formation of the cavities and dislocation loops. Simultaneously, we developped a multiscale modelisation of finite size effets and structure discretisation on equilibrium shapes of cavities based on binding and surface energies determined by ab initio calculation of small vacancy clusters and mixted hydrogen vacancy clusters. Experimental characterization of cavity shapes according to the cavity radius reveals three regular shapes : a cross shape bounded by {100} surfaces, an octahedral non-truncated shape bounded by {111} surfaces and an octahedral truncated shape, bounded by {100} and {111} surfaces as well as the determination of a finite size effect predicted by the model. Also, measurements of cavity shape dispersion during its growth and decrease showed a dominant effet of magic numbers, fixed by geometry and frustration of the structure. Based on a thermodynamic model and a fine experimental characterization of volumic density, we propose a nucleation model of cavities under irradiation. We deduce from this model a critical cluster size and a rate of cavity nucleation depending of temperature and damage, which are compared to the corresponding experimental values extracted from in situ observations. Finally, we discuss the effect of hydrogen on the stability of vacancy-hydrogen clusters and on the kinteic of cavity nucleation