In this thesis we study a test electromagnetic field in the vicinity of Kerr black hole and with methods of extraction of its rotational energy. We are investigating a process in which a particle moves in an electromagnetic resonator around Kerr black hole. The energy of the particle is transferred to the electromagnetic field and the particle falls into the black hole with negative energy. We begin with the derivation of Maxwell's and Teukolsky equations and their numerical solutions. We derive a boundary condition for an electromagnetic field on a spherical mirror around the black hole, find the field that satisfies this condition, and describe the procedure for numerical calculation. Next, we calculate the trajectories of charged test particles in such a field and find particles that fall into the black hole with negative energy. We have found that it is possible for the particle to fall into the black hole with the energy of −124% of its rest mass, and the parameters of the electromagnetic field and trajectory of the particle need to be carefully selected.

In this thesis we study a deformation of a black-hole spacetime due to another strong sources of gravity. Keeping within static and axially symmetric metrics, we consider a binary of Schwarzschild black holes held apart from each other by a repulsive effect of an Appell ring. After verifying that such a system can rest in static equilibrium (without any supporting struts), we compute its several basic geometric characteristics and we plot simple invariants determined by the metric functions (especially lapse, or, equivalently, potential) and by their first and second derivatives (gravitational acceleration and Kretschmann scalar). Then we extend the analysis below the black-hole horizon and inspect the behaviour of the scalars inside. The geometry turns out to be deformed in a non-trivial way, we even find regions of negative Kretschmann scalar in some cases. In the second part, we present a summary of the perturbative solution describing a slowly rotating system of a black hole surrounded by a thin finite circular disc, and an analysis of equatorial circular geodesics in such a spacetime. 1

Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1999. / Includes bibliographical references. / The goal of this thesis was to use high resolution analytical techniques coupled with molecular level analyses to chemically characterize high molecular weight (> 1 k Da (HMW)) dissolved organic matter (DOM) isolated from seawater in an attempt to provide new insights in to the cycling of DOM in the ocean. While a variety of sites spanning different environments (fluvial, coastal and oceanic) and ocean basins were examined, the chemical structure of the isolated HMW DOM varied little at both the polymer and monomer levels. All samples show similar ratios of carbohydrate:acetate:lipid carbon (80±4:10±2:9±4) indicating that these biochemicals are present within a family of related polymers. The carbohydrate fraction shows a characteristic distribution of seven major neutral monosaccharides: rhamnose, fucose, arabinose, xylose, mannose, glucose and galactose; and additionally contains Nacetylated amino sugars as seen by Nuclear Magnetic Resonance Spectroscopy (NMR). This family of compounds, consisting of a specifically linked polysaccharide backbone that is acylated at several positions, has been termed acylated polysaccharides (APS) by our laboratory. APS accounts for 50% of the carbon in HMW DOM isolated from the surface ocean and 20% of the carbon in HMW DOM isolated from the deep ocean. In order to identify a possible source for APS three species of phytoplankton, Thalassiossira weissflogii, Emiliania huxleyi and Phaeocystis, were cultured in seawater and their HMW DOM exudates examined by variety of analytical techniques. Both the T. weissflogii and E. huxleyi exudates contain compounds that resemble APS indicating that phytoplankton are indeed a source of APS to the marine environment. Furthermore, the degradation of the T. weissflogii exudate by a natural assemblage of microorganisms indicates that the component resembling APS is more resistant to microbial degradation compared to other polysaccharides present in the culture. Molecular level analyses show the distribution of monosaccharides to be conservative in surface and deep waters suggesting that APS is present throughout the water column. In order to determine the mechanism by which APS is delivered to the deep ocean the [delta]14C value of APS in the deep ocean was compared to the A14C value of the dissolved inorganic carbon (DIC) at the same depth. If the formation of deep water is the dominant mode of transport then both the DIC and APS will have similar [delta]14C values. However, if APS is injected into the deep ocean from particles or marine snow then the [delta]14C value of APS will be higher than the DIC at the same depth. Our results indicate that APS in the deep Pacific Ocean carries a modem [delta]14C value and is substantially enriched in 14C relative to the total HMW DOM and the DIC at that depth. Thus, particle dissolution appears to be the most important pathway for the delivery of APS to the deep ocean. / by Lihini I. Aluwihare. / Ph.D.

Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1998. / Includes bibliographical references (v. 2, leaves 423-433). / The goal of this thesis is to develop a methodology to interpret sound scattered from the seafloor in terms of seafloor structure and subseafloor geological properties. Specifically, this work has been directed towards the interpretation of matched-filtered, beam-formed monostatic acoustic reverberation data acquired on the west flank of the Mid-Atlantic Ridge when the seafloor is insonified by a band-limited, lowgrazing- angle acoustic pulse. This research is based on the hypothesis that observed backscatter signals are produced by a combination.of seafloor (interface) scattering and subseafloor (volume) scattering from structure having variations at scale lengths similar to the wavelength of the insonifying acoustic field. Analysis of monostatic reverberation data acquired during the Site A experiment (Run 1) of the Acoustic Reverberation Special Research Program 1993 Acoustics Cruise suggests that the scattered signals cannot be accounted for quantitatively in terms of large-scale slope, even though a strong correspondence between high intensity backscatter and seafloor ridges is observed. In order to investigate and quantify the actual sources of seafloor scattering, a numerical modeling study of seafloor models is undertaken using a finitedifference solution to the elastic wave equation. Geological data available at Site A and published reports describing geological properties of similar deep ocean crustal regions are used to develop a realistic seafloor model for the study area with realistic constraints on elastic parameters. Wavelength-scale heterogeneity in each model, in the form of seafloor roughness and subseafloor volume heterogeneity is defined using stochastic distributions with Gaussian autocorrelations. These distributions are quantified by their correlation lengths and standard deviation in amplitude. In order to incorporate all seafloor structure in a single parameterization of seafloor scattering, large-scale slope and wavelength-scale seafloor spatial parameters (rms height and correlation length), are included, along with the acoustic beam grazing-angle relative to a horizontal seafloor, in the definition of an 'effective grazing angle'. The Rayleigh roughness parameter, which depends on grazing angle of the insonification, is then redefined using the effective grazing angle and calculated for a variety of seafloor models. Scattering strengths are shown to vary systematically but nonlinearly with the 'effective Rayleigh roughness parameters' of horizontal rough seafloor models. This leads to an approximate interpretation scheme for backscatter intensity. In general, variation in backscattering is found to be dominated by the scattering from rough seafloor. If the seafloor is smooth or very low velocity (e.g., sediment), then scattering from volume heterogeneity becomes an important factor in the backscattered field. Both wavelength-scale seafloor roughness and volume heterogeneity are shown to be capable of producing the levels of variation in intensity observed in monostatic reverberation experiments. Variations in large-scale seafloor slope and subseafloor average velocity are shown to influence the backscatter response of seafloor models. / by Robert John Greaves. / Ph.D.

Hillsborough County, Florida is subject to a variety of natural and technological hazards, which have the potential to threaten both the population and the built environment. This research focuses on several natural hazards (coastal flooding, sink hole, and hurricane) and technological hazards (toxic transportation spills and toxic release from fixed storage facilities) and the population that is potentially exposed to these hazards. Social vulnerability for this population was determined using racial composition, gender, age and household rental/ownership status. Both social vulnerability and exposure to hazardous conditions occur as a continuum across geographical space. The determination of who is exposed; the extent of exposure; and the hazardousness of their environment; requires converting this continuum into discreet values. There is little agreement on how this should be accomplished. The goal of this project is to improve on this situation by developing a multiple hazard map and a social vulnerability map using the best available data with a focus on data integration. The resulting maps were used to determine the extent that the community of Hillsborough County is exposed to hazardous conditions and the social vulnerability of that exposed community. The impact of hazard analysis is dependant on the creation of the hazard map. The hazard map can be affected by application of weighting factors to the individual or groups of hazards. Weighted linear combinations were used to examine how the exposed population changes when different hazard models are used. A technique of cumulative frequency mapping was used to examine how the composition of the exposed population changed as the hazard scores increased. This was useful in visualizing that different vulnerable communities were not exposed to hazards equally. This technique will be useful for future vulnerability/hazard assessments. The results of this research show that the most vulnerable populations in Hillsborough County, Florida are not exposed to the most extreme hazards. Instead the preponderance of the population is moderately vulnerable and is exposed to moderate hazards. It is important to focus on this population to help prepare for and respond to hazardous events and to work toward diminishing their social vulnerability.

La thèse a pour but d’élaborer et d’étudier les potentialités des semi-conducteurs organiques, transporteurs de trous (HTMs) pour l’application photovoltaïque à l’aide de cellules solaires à base de pérovskite (PSCs). Plusieurs familles de molécules HTM ont été préparées et déposées en solution pour l’élaboration des cellules solaires. L'objectif principal étant d'étudier et d’apporter des informations sur la relation entre la structure moléculaire des nouveaux matériaux de transport de trous et les performances photovoltaïques obtenues, cette étude contribue à une meilleure compréhension fondamentale des propriétés requises des matériaux de transport de trous pour de meilleures performances photovoltaïques.La première étude concerne l’élaboration d’une molécule de type p à base de thieno [3,2-b] thiophène comme élément central avec des dérivés de dimethoxytriphenylamine comme donneurs d’électrons aux extrémités. Différentes conformations sont proposées et révèlent des performances photovoltaïques significativement différentes dans les dispositifs PSC. Notons par exemple, qu’une conformation de structure planaire favorisent la conjugaison avec des valeurs élevées de mobilités et conductivités obtenues.Dans la seconde étude, des molécules donneur-accepteurs à base de dérivés d’acridone 9 (10H) comme accepteur ont été élaborés. En y associant différents fragments donneurs d'électrons, on obtient des structures présentant des caractéristiques favorables à la fois pour de bons transferts de charge intramoléculaire (ICT) et des niveaux d’énergie HOMO-LUMO adaptés et favorisant l’injection des trous de la pérovskite vers l’électrode métallique via le HTM. Des études similaires ont été effectuées avec la thioxanthone.A partir d’un précurseur bon marché et d’une préparation aisée, la troisième étude a permis de synthétiser un dérivé de 9,9’-biacridone, molécule push-pull de type p révélant une structure tridimensionnelle, similaire à celle du Spiro-OMeTAD, molécule référence pour les PSCs.Enfin, la dernière étude concerne l’élaboration de molécules donneur-accepteur à base de thiéno [3,4-c] pyrrole-4,6-dione (TPD). La motivation de cette partie est le développement de la molécule à structure planaire améliorant l’empilement π-π dans la fabrication de dispositifs sans joints de grains. Ces molécules possèdent également un fort caractère ICT, une conjugaison π étendue sur toute la structure et une bonne solubilité ce qui en fait un candidat HTM idéal pour la réalisation d’un dispositif PSCs sans dopant. / The aim of the thesis is to develop and study the potential of organic hole transporting materials (HTMs) for photovoltaic applications using perovskite-based solar cells (PSCs). Several families of HTM molecules have been prepared and deposited in solution for the fabrication of solar cells. Since the main objective is to study and provide information on the relationship between the molecular structure of new hole transport materials and the photovoltaic performances obtained, this study contributes to a better fundamental understanding of the required properties of hole transport materials for better photovoltaic performance.The first study concerns the development of p-type molecules based on Thieno [3,2-b] thiophene as a central unit and π-linker with dimethoxytriphenylamine as end-capping electron donors. Different configurations are designed and revealed significantly different photovoltaic performances in the PSC devices. Remarkable, a planar structure with linear conjugation shows higher values of mobility and conductivity than others, thus it improved device performances.In the second study, donor-acceptor molecules based on 9(10H)Acridone derivatives as an acceptor were developed. By incorporating different electron-donating fragments, we obtain structures with favorable characteristics for both good intramolecular charge transfer (ICT) character and adequate HOMO-LUMO energy levels. Their energy levels are suitable for collecting and injecting the holes from perovskite to the metal electrode through the HTM. Similar studies have been done with Thioxanthone.Using a cheap precursor and facile preparation, the third study synthesized a 9.9'-biacridone derivative. These p-type molecules possess a three-dimensional structure which is similar to that of Spiro-OMeTAD, state-of-the-art molecule for PSCs.Finally, the last study focus on the development of donor-acceptor molecules based on thieno [3,4-c] pyrrole-4,6-dione (TPD). The objective is elaboration of the planar structure molecule which could be improved the π-π stacking effect in the device fabrication without grain boundaries. These molecules also own a strong ICT character, an extended π-conjugation on the whole structure and a good solubility which makes it an ideal candidate for the dopant-free HTM in PSCs.

<p>In this master thesis, a system has been designed that is used to detect the perforation holes on a film in a line-scanning film scanner. The film scanner is used to scan regular film taken by high-speed cameras during tests of for example missile launches or vehicle crash tests. </p><p>The system consists of a PLD that detects the perforation holes on the film using a signal from a digital line-scanning CCD camera. A main issue has been to make the detection procedure robust and independent of the different types of films encountered in real life situations. </p><p>The result from the detection is used to generate control signals to the film speed regulation mechanism inside the film scanner that then regulates the velocity of the film. To make the detection and regulation more sensitive, a part-of-line precision has been developed to calculate where, inside a line, the actual hole is positioned. </p><p>The system has been programmed in VHDL, synthesized, implemented and fitted into a Xilinx Spartan (XCS10-3-PC84) Field Programmable Gate Array (FPGA). The implementation has been simulated but not in real hardware.</p>

The work is divided into three main parts. In a first time (chapter 1) we define a “BTZ” black hole in anti de Sitter space in any dimension. That will be done by means of group theoretical and symmetric spaces considerations. A physical “good domain” is identified as an open orbit of a subgroup of the isometry group of anti de Sitter. Then (chapter 2) we show that the open orbit is in fact isomorphic to a group (we introduce the notion of globally group type manifold) for which a quantization exists. The quantization of the black hole is performed and its Dirac operator is computed. The third part (appendix A and B) exposes some previously known results. Appendix A is given in a pedagogical purpose: it exposes generalities about deformation quantization and careful examples with SL(2,R), and split extensions of Heisenberg algebras. Appendix B is devoted to some classical results about homogeneous spaces and Iwasawa decompositions. Explicit decompositions are given for every algebra that will be used in the thesis. It serves to make the whole text more self contained and to fix notations. Basics of quantization by group action are given in appendix A.4. One more chapter is inserted (chapter 3). It contains two small results which have no true interest by themselves but which raise questions and call for further development. We discuss a product on the half-plane or, equivalently, on the Iwasawa subgroup of SL(2,R), due to A. Unterberger. We show that the quantization by group action machinery can be applied to this product in order to deform the dual of the Lie algebra of that Iwasawa subgroup. Although this result seems promising, we show by two examples that the product is not universal in the sense that even the product of compactly supported functions cannot be defined on AdS2 by the quantization induced by Unterberger's product. Then we show that the Iwasawa subgroup of SO(2,n) (i.e. the group which defines the singularity) is a symplectic split extension of the Iwasawa subgroup of SU(1,1) by the Iwasawa subgroup of SU(1,n). A quantization of the two latter groups being known, a quantization of SO(2,n) is in principle possible using an extension lemma. Properties of this product and the resulting quantization of AdSl were not investigated because we found a more economical way to quantize AdS4 .

Solar energy is the foremost power source of our planet. Driving photosynthesis on our planet for 3 billion years the energy stored in the form of fossil fuels also originates from the sun. Consumption of fossil fuels to generate energy is accompanied with CO2 emission which affects the earth's climate in a serious manner. Therefore, alternative ways of converting energy have to be found. Solar cells convert sunlight directly into electricity and are therefore an important technology for future electricity generation. In this work solar cells based on the inorganic semiconductor titanium dioxide and hole-transporting dyes are investigated. These type of solar cells are categorized as hybrid solar cells and are conceptually related to both dye-sensitized solar cells and organic solar cells. Light absorption in the bulk of the hole-transporting dye layer leads to the formation of excitons that can be harvested at the organic/inorganic interface. Two design approaches were investigated: 1) utilizing a multilayer of a hole-transporting dye and 2) utilizing a hole-transporting dye as light harvesting antenna to another dye which is bound to the titanium dioxide surface.  Using a multiple dye layer in titanium dioxide/hole transporting dye devices, leads to an improved device performance as light harvested in the consecutive dye layers can contribute to the photocurrent. In devices using both an inteface-bound dye and a hole-transporting dye, excitation energy can be transferred from the hole-transporting dye to the interface dye.

The Diels-Alder reaction is one of the most powerful synthetic tools in organic chemistry, and asymmetric Diels-Alder catalysis allows for rapid construction of chiral carbon scaffolds. For this reason, considerable effort has been invested in developing efficient and stereoselective organo- and biocatalysts. However, Diels-Alder is a virtually unknown reaction in Nature, and to engineer an enzyme into a Diels-Alderase is therefore a challenging task. Despite several successful designs of catalytic antibodies since the 1980’s, their catalytic activities have remained low, and no true artificial ’Diels-Alderase’ enzyme was reported before 2010. In this thesis, we employ state-of-the-art computational tools to study the mechanism of organocatalyzed Diels-Alder in detail, and to redesign existing enzymes into intermolecular Diels-Alder catalysts. Papers I–IV explore the mechanistic variations when employing increasingly activated reactants and the effect of catalysis. In particular, the relation between the traditionally presumed concerted mechanism and a stepwise pathway, forming one bond at a time, is probed. Papers V–X deal with enzyme design and the computational aspects of predicting catalytic activity. Four novel, computationally designed Diels-Alderase candidates are presented in Papers VI–IX. In Paper X, a new parameterization of the Linear Interaction Energy model for predicting protein-ligand affinities is presented. A general finding in this thesis is that it is difficult to attain large transition state stabilization effects solely by hydrogen bond catalysis. In addition, water (the preferred solvent of enzymes) is well-known for catalyzing Diels- Alder by itself. Therefore, an efficient Diels-Alderase must rely on large binding affinities for the two substrates and preferential binding conformations close to the transition state geometry. In Papers VI–VIII, we co-designed the enzyme active site and substrates in order to achieve the best possible complementarity and maximize binding affinity and pre-organization. Even so, catalysis is limited by the maximum possible stabilization offered by hydrogen bonds, and by the inherently large energy barrier associated with the [4+2] cycloaddition. The stepwise Diels-Alder pathway, proceeding via a zwitterionic intermediate, may offer a productive alternative for enzyme catalysis, since an enzyme active site may be more differentiated towards stabilizing the high-energy states than for the standard mechanism. In Papers I and III, it is demonstrated that a hydrogen bond donor catalyst provides more stabilization of transition states having pronounced charge-transfer character, which shifts the preference towards a stepwise mechanism. Another alternative, explored in Paper IX, is to use an α,β -unsaturated ketone as a ’pro-diene’, and let the enzyme generate the diene in situ by general acid/base catalysis. The results show that the potential reduction in the reaction barrier with such a mechanism is much larger than for conventional Diels-Alder. Moreover, an acid/base-mediated pathway is a better mimic of how natural enzymes function, since remarkably few catalyze their reactions solely by non-covalent interactions. / <p>QC 20120903</p>