311 |
Earth satellites and air and ground-based activitiesEkblad, Ulf January 2004 (has links)
<p>This thesis, Earth satellites and detection of air andground based activities by Ulf Ekblad of the Physics departmentat the Royal Institute of Technology (KTH), addresses theproblem of detecting military activities in imagery. Examplesof various techniques are presented. In particular, problemsassociated with "novelties" and "changes" in an image arediscussed and various algorithms presented. The imagery usedincludes satellite imagery, aircraft imagery, and photos offlying aircraft.</p><p>The timely delivery of satellite imagery is limited by thelaws of celestial mechanics. This and other information aspectsof imagery are treated. It is e.g. shown that dozens ofsatellites may be needed if daily observations of a specificsite on Earth are to be conducted from low Earth orbit.</p><p>New findings from bioinformatics and studies of small mammalvisual systems are used. The Intersecting Cortical Model (ICM),which is a reduced variant of the Pulse-Coupled Neural Network(PCNN), is used on various problems among which are changedetection. Still much more could be learnt from biologicalsystems with respect to pre- and post-processing as well asintermediate processing stages.</p><p>Simulated satellite imagery is used for determining theresolution limit for detection of tanks. The necessary pixelsize is shown to be around 6 m under the conditions of thissimulation.</p><p>Difference techniques are also tested on Landsat satelliteimagery with the purpose of detecting underground nuclearexplosions. In particular, it is shown that this can easily bedone with 30 m resolution images, at least in the case studied.Satellite imagery from SPOT is used for detecting undergroundnuclear explosions prior to the detonations, i.e. under certainconditions 10 m resolution images can be used to detectpreparations of underground nuclear explosions. This type ofinformation is important for ensuring the compliance of nucleartest ban treaties. Furthermore, the necessity for havingcomplementary information in order to be able to interpretimages is also shown.</p><p>Keywords: Remote sensing, reconnaissance, sensor,information acquisition, satellite imagery, image processing,image analysis, change detection, pixel difference, neuronnetwork, cortex model, PCNN, ICM, entanglement, Earthobservation, nuclear explosion, SPOT, Landsat, verification,orbit.</p>
|
312 |
Spectroscopie d'intrication et son application aux phases de l'effet Hall quantique fractionnaireRegnault, Nicolas 27 May 2013 (has links) (PDF)
La spectroscopie d'intrication, initialement introduite par Li et Haldane dans le contexte de l'effet Hall quantique fractionnaire, a suscité un large éventail de travaux. Le spectre d'intrication est le spectre de la matrice de densité réduite, quand on partitionne le système en deux. Pour de nombreux systèmes quantiques, il révèle une caractéristique unique : calculé uniquement à partir de la fonction d'onde de l'état fondamental, le spectre d'intrication donne accès à la physique des excitations de bord. Dans ce manuscrit, nous donnons un apercu de la spectroscopie d'intrication. Nous introduisons les concepts de base dans le cas des chaînes de spins quantiques. Nous présentons une étude approfondie des spectres d'intrication appliqués aux phases de l'effet Hall quantique fractionnaire, montrant quel type d'information est encodé dans l'état fondamental et comment les différentes facons de partitionner le système permettent de sonder différents types d'excitation. Comme application pratique de cette technique, nous discutons de la manière dont cette technique peut aider à faire la distinction entre les différentes phases qui émergent dans les isolants de Chern en interaction forte.
|
313 |
Exciton-polaritons in low dimensional structuresPavlovic, Goran 17 November 2010 (has links) (PDF)
Some special features of polaritons, quasi-particles being normal modes of system of excitons interacting with photons in so called strong coupling regime, are theoretically and numerically analyze in low dimensional systems. In Chapter 1 is given a brief overview of 0D, 1D and 2D semiconductor structures with a general introduction to the polariton field. Chapter 2 is devoted to micro / nano wires. The so called whispering gallery modes are studied in the general case of an anisotropic systems as well as polariton formation in ZnO wires. Theoretical model is compared with an experiment. In the Chapter 3 Josephson type dynamics with Bose-Einstein condensates of polaritons is analyzed taking into account pseudospin degree of freedom. Chapter 4 start with an introduction to Aharonov-Bohm effect, as the best known represent of geometrical phases. An another geometrical phase - Berry phase, occurring for a wide class of systems performing adiabatic motion on a closed ring, is main subject of this section. We considered one proposition for an exciton polariton ring interferometer based on Berry phase effect. Chapter 5 concerns one 0D system : strongly coupled quantum dot exciton to cavity photon. We have discussed possibility of obtaining entangled states from a quantum dot embedded in a photonic crystal in polariton regime.
|
314 |
Strong interactions in alkaline-earth Rydberg ensemblesMukherjee, Rick 17 December 2014 (has links) (PDF)
Ultra-cold atoms in optical lattices provide a versatile and robust platform to study fundamental condensed-matter physics problems and have applications in quantum optics as well as quantum information processing. For many of these applications, Rydberg atoms (atoms excited to large principal quantum numbers) are ideal due to its long coherence times and strong interactions.
However, one of the pre-requisite for such applications is identical confinement of ground state atoms with Rydberg atoms. This is challenging for conventionally used alkali atoms. In this thesis, I discuss the potential of using alkaline-earth Rydberg atoms for many-body physics by implementing simultaneous trapping for the relevant internal states. In particular, I consider a scheme for generating multi-particle entanglement and explore charge transport in a one dimensional atomic lattice.
|
315 |
Semiflexible Polymer NetworksGlaser, Jens 19 July 2011 (has links) (PDF)
Die vorliegende Arbeit beschäftigt sich mit der theoretischen Beschreibung der komplexen physikalischen Eigenschaften von Netzwerken semiflexibler Polymere. Ausgehend vom mathematischen Modell eines semiflexiblen Polymers, der \"wurmartigen Kette\" (wormlike chain), werden zwei wesentlich neue Konzepte zur Beschreibung dieses ungeordneten Materialzustands eingeführt. Einerseits wird das experimentell beobachtete, glasähnliche Fließen solcher Materialien durch das phänomenologische Modell eines semiflexiblen Polymers mit verallgemeinerter Reibung beschrieben, welche den Gesamteffekt der physikalischen oder auch chemischen Wechselwirkungen der Polymere untereinander widerspiegelt. Andererseits wird das bestehende Konzept der durch seine Nachbarfilamente erzeugten röhrenförmigen Einsperrung eines Filaments erweitert und die experimentell nachgewiesene, räumlich veränderliche Struktur der Röhre erklärt. Die erzielten Ergebnisse werden durch Rechnersimulationen sowie durch experimentelle Daten gestützt.
|
316 |
The Crematorium of Hanga Hahave on Rapa Nui (Easter Island): What stories can the skeletal remains reveal. / Krematoriet i Hanga Hahave på Rapa Nui (Påskön): Vilka historier kan de skeletala kvarlevor berätta.Navarro, Sigourney Nina January 2017 (has links)
This paper uses an osteological approach and applies the study of entanglement in an attempt to understand the crematoria on Rapa Nui (Easter Island), which represent a unique tradition within the ceremonial spheres of the Polynesian area. Skeletal remains from the crematorium of ahu Hanga Hahave, which consist of both cremated - and unburned remains, have been analysed to reveal the different practices that took part in the cremation process and to identify the individuals that were deposited in such structure. Ethnohistorical records were applied to interpret the osteological evidence and to discuss the circumstances surrounding the possible use of the crematorium, as either a site for sacrificial offerings or a site for burials. This paper aims at creating an underlying basis for the study of crematoria on Rapa Nui and provides an overview of the processes central to the disposal of the dead and the usage and significance of this structure. The results of this study showed that the ancient Rapanui through the practice of cremation, followed an internalised structure within their society to complete each cultural act that constituted the crematorium, and these were divided in the construction of the crematorium, the making of fire, and the treatment of the dead. The complexity of each cultural act presents the possibility that an organised society, with at least one designated head, may have been in charge of the practice of cremation physically and spiritually. The skeletal remains could not be applied to determine whether the crematorium of Hanga Hahave was used for sacrificial offering or for burial since the analysed remains only represented one-fifth of the entire bone collection from the crematorium. However, the findings of this study have pointed towards a burial practice rather than a sacrificial one. / Denna uppsats använder ett osteologiskt tillvägagångssätt och Hodders’’entanglement’ studie i tolkningen av krematorierna på Rapa Nui (Påskön), som representerar en unik tradition inom Polynesien. Skelettmaterialet från krematoriet i ahu Hanga Hahave har analyserats för att upptäcka de olika metoder som deltog i kremeringsprocessen och identifiera vilka individer som deponerades här. Etnohistoriska källor användes också i tolkningen av det osteologiska materialet och för att behandla frågorna kring krematoriernas användning: antigen som en plats för offring eller en plats för begravning. Syftet är att skapa en underliggande grund för studiet av krematorierna på Rapa Nui för att ge en överblick på de centrala processerna. Resultatet visade att den forntida Rapanui följde en internaliserad struktur inom sitt samhälle för att slutföra varje kulturell handling som utgjorde kremerings praktik och var uppdelade i konstruktionen av krematoriet, bruken av eld och hantering av de döda. Komplexiteten hos varje handling möjliggör att ett organiserat samhälle, där minst en ledare har varit ansvarig i fysisk eller andlig form. Skelettmaterialet från krematoriet i ahu Hanga Hahave kunde inte användas för att bestämma krematoriets användning eftersom det analyserade materialet endast representerade en femtedel av den totala bensamlingen, dock pekar studiet på en begravningsritual snarare än en offer.
|
317 |
Complementaridade de buracos negros e a conexão entre emaranhamento e geometria.VELOSO, Ildemar Barreto. 17 October 2018 (has links)
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-17T17:33:09Z
No. of bitstreams: 1
Dissertação-Ildemar Barreto Veloso -(OK).pdf: 627444 bytes, checksum: ba9ac192a954812365d05a8c75c86647 (MD5) / Made available in DSpace on 2018-10-17T17:33:09Z (GMT). No. of bitstreams: 1
Dissertação-Ildemar Barreto Veloso -(OK).pdf: 627444 bytes, checksum: ba9ac192a954812365d05a8c75c86647 (MD5)
Previous issue date: 2016-09 / Capes / A Relatividade Geral, que foi construída baseada nos princípios da equivalência
e da covariância,é a teoria da gravitação que admite um espaço-tempo não euclidiano.
Ela permite que o espaço-tempo se torne curvo próximo à distribuições de matéria. Os
buracos negros são objetos com imensas concentrações de matéria, que provocam grandes perturbações no espaço a sua volta. A métrica correspondente ao buraco negro que analisamos foi a de Schwarzschild. Tais objetos também podem ser analisados utilizando-se a termodinâmica, com a obtenção de variáveis como temperatura e entropia. Este último conceito, é de fundamental importância para entendermos a questão do emaranhamento entre dois sistemas físicos correlacionados e a teoria de informação. Assim, nosso objetivo foi analisar alguns fatores sobre o paradoxo da conservação da informação em buracos negros. Além do mais, também analisamos como o emaranhamento entre duas regiões desconectadas pode gerar espaços-tempos conectados, e qual sua relação com as pontes deEinstein-Rosen. / The General Relativity, that was built on the equivalence and covariance principles, is the gravitation the or which admits an on-euclide an space time. It permits that the space time be comes curve near matter distributions. The black holes are objects with huge concentrations of matter, which cause major disruption in the space around it.The corresponding metric to the black hole that were view edit is the Schwarzschildmetric.
Such objects canal sobe analyzed using the thermo dynamic concepts, to obtain variables such as temperature and entropy. This one, will be of fundamental importance to understanding the question of the entanglement between two related physical systems
and the concept of information. So, ourgo alitis to examine some factors aboutt he
information conservation paradox in black holes. Moreover, also we analyzedas a entan-
glement between two disconnected regions can generate space time connected,and what
is its relationship with Einstein-Rosenbridges.
|
318 |
Étude de semiconducteurs par des techniques de spectroscopie quantiqueLeroux, Jimmy 12 1900 (has links)
No description available.
|
319 |
Moira, take me with you! : Utopian Hope and Queer Horizons in Three Versions of The Handmaid's TaleMarx, Hedvig January 2018 (has links)
Using postmodern, feminist and queer notions of utopia/dystopia and narrative theory, this thesis contains an analysis of The Handmaid’s Tale (novel 1985; film 1990; TV series S01 2017) based on theoretical and methodological understandings of utopia/dystopia and narrative as deeply connected with notions of temporality and relationality, and of violence and resistance as the modes of expression of utopia and dystopia in the source texts. The analysis is carried out in an explorative manner (Czarniawska 2004) and utilises the notion of “disidentification” (Butler 1993; Muñoz 1999) and the concepts of “diffraction” (Haraway 1992, 1997; Barad 2007, 2010), and “entanglement” (Barad 2007). The conclusion becomes that utopia and dystopia in The Handmaid’s Tale are, to a great extent, imagined within the same system of understanding, but that utopian hope can be found in the relationality and temporality of resistance, and that the radically different utopian place is the queer horizon.
|
320 |
Entanglement, boundaries and holography / Intrication, bords et holographieBerthiere, Clément 20 December 2017 (has links)
La notion d’entropie d’intrication a eu un profond impact sur la physique théorique, particulièrement depuis ces dix dernières années. D’abord introduite afin expliquer l’entropie des trous noirs, son champ d’application s’est par la suite ouvert à une grande variété de domaines de recherche, de la matière condensée à la gravitation quantique, de l’information quantique à la théorie quantique des champs. Dans ce contexte scientifique effervescent, l’entropie d’intrication apparait comme un outil central et doit donc intensivement être étudiée. A l’origine de cette thèse se trouve le désir de mieux comprendre cette entropie. D’intéressants développements concernant les effets de bord sur l’entropie d’intrication ont vu le jour récemment. Nous proposons donc d’explorer comment le bord d’un espace affecte l’entropie, en particulier dans la situation où la surface d’intrication intersecte ce bord. Nous présentons des calculs explicites de l’entropie d’intrication en espace plat avec bords. Nous montrons que des termes induits par ces bords apparaissent dans l’entropie et nous soulignons le rôle prépondérant que jouent les conditions aux bords. Nous étudions ensuite la contribution de bord dans le terme logarithmique de l’entropie d’intrication en dimensions trois et quatre. Nous calculons en premier lieu ce terme en théorie des champs pour la théorie N = 4 de Yang-Mills, puis nous répétons ce calcul de manière holographique. Nous montrons que ces deux méthodes de calcul donnent le même résultat, si du côté théorie des champs les conditions aux bords préservent la moitié de la supersymétrie et que du côté gravité l’extension du bord dans le bulk est une surface minimale. / The entanglement entropy has had a tremendous and profound impact on theoretical physics, particularly since the last decade. First introduced in an attempt to explain black holes entropy, it has then found applications in a wide range of research areas, from condensed matter physics to quantum gravity, from quantum information to quantum field theory. In this exciting scientific context, the entanglement entropy has thus emerged as a useful and pivotal tool, and as such justifies the need to be intensively studied. At the heart of this thesis therefore lies the desire to better understand the entanglement entropy. Interesting developments during the recent years concern the boundary effects on the entanglement entropy. This dissertation proposes to explore the question of how the presence of spacetime boundaries affects the entropy, specifically in situations where the entangling surface intersects these boundaries. We present explicit calculations of entanglement entropy in flat spacetime with plane boundaries. We show that boundary induced terms appear in the entropy and we emphasize the prominent role of the boundary conditions. We then study the boundary contribution to the logarithmic term in the entanglement entropy in three and four dimensions. We perform the field theoretic computation of this boundary term for the free N = 4 super-gauge multiplet and then repeat the same calculation holographically. We show that these two calculations are in agreement provided that on the field theory side one chooses the boundary conditions which preserve half of the full supersymmetry and that on the gravity side the extension of the boundary in the bulk is minimal.
|
Page generated in 0.0883 seconds