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1
Bridle, Ismail Hamzaan. "Non-polynomial scalar field potentials in the local potential approximation." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/410270/.
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We present the renormalisation group analysis of O(N) invariant scalar field theory in the local potential approximation. Linearising around the Gaussian fixed point, we find the same eigenoperators solutions exist for both the Wilsonian and the Legendre effective actions, given by solutions to Kummer’s equations. We find the usual polynomial eigenoperators and the Hilbert space they define are a natural subset of these solutions given by a specific set of quantised eigenvalues. Allowing for continuous eigenvalues, we find non-polynomial eigenoperator solutions, the so called Halpern-Huang directions, that exist outside of the polynomial Hilbert space due to the exponential field dependence. Carefully analysing the large field behaviour shows that the exponential dependence implies the Legendre effective action does not have a well defined continuum limit. In comparison, flowing towards the infrared we find that the non-polynomial eigenoperators flow into the polynomial Hilbert space. These conclusions are based off RG flow initiated at an arbitrary scale, implying non-polynomial eigenoperators are dependent upon a scale other than k. Therefore, the asymptotic field behaviour forbids self-similar scaling. These results hold when generalised from the Halpern-Huang directions around the Gaussian fixed point to a general fixed point with a general non-polynomial eigenoperator. Legendre transforming to results of the Polchinski equation, we find the flow of the Wilsonian effective action is much better regulated and always fall into the polynomial Hilbert space. For large Wilsonian effective actions, we find that the non-linear terms of the Polchinski equation forbid any non-polynomial field scaling, regardless of the fixed point. These observations lead to the conclusion that only polynomial eigenoperators show the correct, self-similar, scaling behaviour to construct a non-perturbatively renormalisable scalar QFT.
2
Riquier, Raphaël. "Magnetic field in laser plasmas : non-local electron transport and reconnection." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX004/document.
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Dans le cadre de la fusion par confinement inertiel, une capsule contenant le combustible de deutérium-tritium est implosée soit par irradiation laser (attaque directe, interaction laser – cible de numéro atomique faible), soit par un rayonnement de corps noir émis par une cavité convertissant le rayonnement laser (attaque indirecte, interaction laser – cible de numéro atomique élevé).Dans les deux cas, une modélisation correcte du transport électronique est cruciale pour avoir des simulations hydro-radiatives prédictives. Cependant, il a été montré très tôt que les hypothèses d'un mécanisme de transport linéaire ne sont pas applicables dans le cadre de l'irradiation d'une cible solide par un laser de puissance (I~10^14 W/cm²). Cela est dû d'une part à des gradients de température très importants (effets cinétiques dits « non-locaux ») ainsi qu'à la présence d'un champ magnétique auto-généré par effet thermo-électrique. Enfin, le flux de chaleur et le champ magnétique sont fortement couplés au travers de deux mécanismes : le transport du champ magnétique par le flux de chaleur (effet Nernst) et la rotation et inhibition du flux de chaleur par la magnétisation du plasma (effet Righi-Leduc).Dans le présent manuscrit, nous commencerons par exposer les différents modèles de transport électronique, et en particulier le modèle non-local avec champ magnétique, implémenté dans le code hydro-radiatif FCI2. Par la suite, nous chercherons à valider ce modèle par des comparaisons avec un code cinétique, puis avec une expérience lors de laquelle le champ magnétique a été mesuré par radiographie proton. Cela fait, nous utiliserons le code FCI2 pour expliquer la source et le transport du champ, ainsi que son effet sur l'interaction.Enfin, nous étudierons la reconnexion du champ magnétique, lors de l'irradiation d'une cible par deux faisceaux lasers<br>In the framework of the inertial confinement fusion, a pellet filled with the deuterium-tritium fuel is imploded, either through laser irradiation (direct drive, laser – low atomic number target interaction) or by the black body radiation from a cavity converting the laser radiation (indirect drive, laser – high atomic number target interaction).In both cases, a correct modeling of the electron transport is of first importance in order to have predictive hydro-radiative simulations. Nonetheless, it has been shown early on that the hypothesis of the linear transport are not valid in the framework of a solid target irradiated by a high power laser (I~1014 W/cm²). This is due in part to very steep temperature gradients (kinetic effects, so-called « non-local ») and because of a magnetic field self-generated through the thermo-electric effect. Finally, the heat flux and the magnetic field are strongly coupled through two mecanisms: the advection of the field with the heat flux (Nernst effect) and the rotation and inhibition of the heat flux by the plasma's magnetization (Righi-Leduc effect).In this manuscript, we will first present the various electron transport models, particularly the non-local with magnetic field model included in the hydro-radiative code FCI2. Following, in order to validate this model, we will compare it first against a kinetic code, and then with an experiment during which the magnetic field has been probed through proton radiography. Once the model validated, we will use FCI2 simulations to explain the source and transport of the field, as well as its effect on the interaction.Finally, the reconnection of the magnetic field, during the irradiation of a solid target by two laser beams, will be studied
3
Frailey, Conor Nelson. "Representations of the General Linear Groupoid Over a Non-Archimedean Local Field." Thesis, Yale University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3580686.
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Florin, Esther [Verfasser]. "Causality measures between neural signals from invasively and non-invasively obtained local field potentials in humans / Esther Florin." Wuppertal : Universitätsbibliothek Wuppertal, 2010. http://d-nb.info/1006178449/34.
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Kawamura, Koei. "Infinite-variate extensions of Krawtchouk polynomials and zonal spherical functions over a local field." Kyoto University, 2018. http://hdl.handle.net/2433/232216.
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Cao, Xiaodong [Verfasser], and Philipp [Akademischer Betreuer] Hansmann. "Extensions of dynamical mean-field theory to non-local correlations and multi-band systems / Xiaodong Cao ; Betreuer: Philipp Hansmann." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1217253378/34.
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7
Chinner, Trinity. "Elliptic Tori in p-adic Orthogonal Groups." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42759.
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In this thesis, we classify up to conjugacy the maximal elliptic toral subgroups of all
special orthogonal groups SO(V), where (q,V) is a 4-dimensional quadratic space
over a non-archimedean local field of odd residual characteristic. Our parameterization blends the abstract theory of Morris with a generalization of the practical work
performed by Kim and Yu for Sp(4). Moreover, we compute an explicit Witt basis
for each such torus, thereby enabling its concrete realization as a set of matrices embedded into the group. This work can be used explicitly to construct supercuspidal
representations of SO(V).
8
Wang, Chao. "Exploiting non-redundant local patterns and probabilistic models for analyzing structured and semi-structured data." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1199284713.
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Supe, Kristin Edwards. "Role of Rat Neuronal Oscillations in Acquisition and Disruption of Working Memory with Acute Ethanol." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1404732893.
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10
Mehmeti, Vlere. "Patching on Berkovich Spaces and the Local-Global Principle." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC240.
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Le recollement sur les corps, introduit par Harbater et Hartmann, et étendu par ces auteurs et Krashen, a récemment trouvé de nombreuses applications. Nous présentons ici une extension de cette technique au cadre de la géométrie analytique de Berkovich et des applications au principe local-global.Nous montrons que cette adaptation du recollement peut s'appliquer aux courbes analytiques de Berkovich, et par conséquent obtenons des principes locaux-globaux sur les corps de fonctions de courbes définies sur des corps ultramétriques complets. Grâce à la connexion entre les points d'une courbe analytique de Berkovich et les valuations dont on peut munir son corps de fonctions, nous obtenons un principe local-global par rapport à des complétés du corps de fonctions considéré, ce qui présente une ressemblance avec des versions plus classiques. En application, nous établissons des principes locaux-globaux dans le cas plus précis des formes quadratiques et en déduisons des bornes sur l'u-invariant de certains corps. Nos résultats généralisent ceux de Harbater, Hartmann et Krashen.Comme point de départ pour le recollement en dimension supérieure dans un cadre d'espaces de Berkovich, nous montrons que cette technique peut s'appliquer autour de certaines fibres d'une courbe analytique relative. Nous l'utilisons ensuite pour démontrer un principe local-global sur les germes des fonctions méromorphes sur ces fibres. En montrant que ces germes de fonctions méromorphes sont algébriques, nous obtenons aussi des principes locaux-globaux sur les corps de fonctions des courbes algébriques définies sur une famille plus vaste de corps ultramétriques<br>Field patching, introduced by Harbater and Hartmann, and extended by the aforementioned authors and Krashen, has recently seen numerous applications. We present an extension of this technique to the setting of Berkovich analytic geometry and applications to the local-global principle.In particular, we show that this adaptation of patching can be applied to Berkovich analytic curves, and as a consequence obtain local-global principles over function fields of curves defined over complete ultrametric fields. Because of the connection between the points of a Berkovich analytic curve and the valuations that its function field can be endowed with, one of these local-global principles is given with respect to completions, thus evoking some similarity with more classical versions. As an application, we obtain local-global principles for quadratic forms and results on the u-invariant. These findings generalize those of Harbater, Hartmann and Krashen.As a starting point for higher-dimensional patching in the Berkovich setting, we show that this technique is applicable around certain fibers of a relative Berkovich analytic curve. As a consequence, we prove a local-global principle over the germs of meromorphic functions on said fibers. By showing that said germs of meromorphic functions are algebraic, we also obtain local-global principles over function fields of algebraic curves defined over a larger class of ultrametric fields
11
Vogel, Michael Werner. "Theoretical and numerical investigation of plasmon nanofocusing in metallic tapered rods and grooves." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/29241/1/Michael_Vogel_Citation.pdf.
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Effective focusing of electromagnetic (EM) energy to nanoscale regions is one of the major challenges in nano-photonics and plasmonics. The strong localization of the optical energy into regions much smaller than allowed by the diffraction limit, also called nanofocusing, offers promising applications in nano-sensor technology, nanofabrication, near-field optics or spectroscopy. One of the most promising solutions to the problem of efficient nanofocusing is related to surface plasmon propagation in metallic structures. Metallic tapered rods, commonly used as probes in near field microscopy and spectroscopy, are of a particular interest. They can provide very strong EM field enhancement at the tip due to surface plasmons (SP’s) propagating towards the tip of the tapered metal rod. A large number of studies have been devoted to the manufacturing process of tapered rods or tapered fibers coated by a metal film. On the other hand, structures such as metallic V-grooves or metal wedges can also provide strong electric field enhancements but manufacturing of these structures is still a challenge. It has been shown, however, that the attainable electric field enhancement at the apex in the V-groove is higher than at the tip of a metal tapered rod when the dissipation level in the metal is strong. Metallic V-grooves also have very promising characteristics as plasmonic waveguides. This thesis will present a thorough theoretical and numerical investigation of nanofocusing during plasmon propagation along a metal tapered rod and into a metallic V-groove. Optimal structural parameters including optimal taper angle, taper length and shape of the taper are determined in order to achieve maximum field enhancement factors at the tip of the nanofocusing structure. An analytical investigation of plasmon nanofocusing by metal tapered rods is carried out by means of the geometric optics approximation (GOA), which is also called adiabatic nanofocusing. However, GOA is applicable only for analysing tapered structures with small taper angles and without considering a terminating tip structure in order to neglect reflections. Rigorous numerical methods are employed for analysing non-adiabatic nanofocusing, by tapered rod and V-grooves with larger taper angles and with a rounded tip. These structures cannot be studied by analytical methods due to the presence of reflected waves from the taper section, the tip and also from (artificial) computational boundaries. A new method is introduced to combine the advantages of GOA and rigorous numerical methods in order to reduce significantly the use of computational resources and yet achieve accurate results for the analysis of large tapered structures, within reasonable calculation time. Detailed comparison between GOA and rigorous numerical methods will be carried out in order to find the critical taper angle of the tapered structures at which GOA is still applicable. It will be demonstrated that optimal taper angles, at which maximum field enhancements occur, coincide with the critical angles, at which GOA is still applicable. It will be shown that the applicability of GOA can be substantially expanded to include structures which could be analysed previously by numerical methods only. The influence of the rounded tip, the taper angle and the role of dissipation onto the plasmon field distribution along the tapered rod and near the tip will be analysed analytically and numerically in detail. It will be demonstrated that electric field enhancement factors of up to ~ 2500 within nanoscale regions are predicted. These are sufficient, for instance, to detect single molecules using surface enhanced Raman spectroscopy (SERS) with the tip of a tapered rod, an approach also known as tip enhanced Raman spectroscopy or TERS. The results obtained in this project will be important for applications for which strong local field enhancement factors are crucial for the performance of devices such as near field microscopes or spectroscopy. The optimal design of nanofocusing structures, at which the delivery of electromagnetic energy to the nanometer region is most efficient, will lead to new applications in near field sensors, near field measuring technology, or generation of nanometer sized energy sources. This includes: applications in tip enhanced Raman spectroscopy (TERS); manipulation of nanoparticles and molecules; efficient coupling of optical energy into and out of plasmonic circuits; second harmonic generation in non-linear optics; or delivery of energy to quantum dots, for instance, for quantum computations.
12
Vogel, Michael Werner. "Theoretical and numerical investigation of plasmon nanofocusing in metallic tapered rods and grooves." Queensland University of Technology, 2009. http://eprints.qut.edu.au/29241/.
Full textAbstract:
Effective focusing of electromagnetic (EM) energy to nanoscale regions is one of the major challenges in nano-photonics and plasmonics. The strong localization of the optical energy into regions much smaller than allowed by the diffraction limit, also called nanofocusing, offers promising applications in nano-sensor technology, nanofabrication, near-field optics or spectroscopy. One of the most promising solutions to the problem of efficient nanofocusing is related to surface plasmon propagation in metallic structures. Metallic tapered rods, commonly used as probes in near field microscopy and spectroscopy, are of a particular interest. They can provide very strong EM field enhancement at the tip due to surface plasmons (SP’s) propagating towards the tip of the tapered metal rod. A large number of studies have been devoted to the manufacturing process of tapered rods or tapered fibers coated by a metal film. On the other hand, structures such as metallic V-grooves or metal wedges can also provide strong electric field enhancements but manufacturing of these structures is still a challenge. It has been shown, however, that the attainable electric field enhancement at the apex in the V-groove is higher than at the tip of a metal tapered rod when the dissipation level in the metal is strong. Metallic V-grooves also have very promising characteristics as plasmonic waveguides. This thesis will present a thorough theoretical and numerical investigation of nanofocusing during plasmon propagation along a metal tapered rod and into a metallic V-groove. Optimal structural parameters including optimal taper angle, taper length and shape of the taper are determined in order to achieve maximum field enhancement factors at the tip of the nanofocusing structure. An analytical investigation of plasmon nanofocusing by metal tapered rods is carried out by means of the geometric optics approximation (GOA), which is also called adiabatic nanofocusing. However, GOA is applicable only for analysing tapered structures with small taper angles and without considering a terminating tip structure in order to neglect reflections. Rigorous numerical methods are employed for analysing non-adiabatic nanofocusing, by tapered rod and V-grooves with larger taper angles and with a rounded tip. These structures cannot be studied by analytical methods due to the presence of reflected waves from the taper section, the tip and also from (artificial) computational boundaries. A new method is introduced to combine the advantages of GOA and rigorous numerical methods in order to reduce significantly the use of computational resources and yet achieve accurate results for the analysis of large tapered structures, within reasonable calculation time. Detailed comparison between GOA and rigorous numerical methods will be carried out in order to find the critical taper angle of the tapered structures at which GOA is still applicable. It will be demonstrated that optimal taper angles, at which maximum field enhancements occur, coincide with the critical angles, at which GOA is still applicable. It will be shown that the applicability of GOA can be substantially expanded to include structures which could be analysed previously by numerical methods only. The influence of the rounded tip, the taper angle and the role of dissipation onto the plasmon field distribution along the tapered rod and near the tip will be analysed analytically and numerically in detail. It will be demonstrated that electric field enhancement factors of up to ~ 2500 within nanoscale regions are predicted. These are sufficient, for instance, to detect single molecules using surface enhanced Raman spectroscopy (SERS) with the tip of a tapered rod, an approach also known as tip enhanced Raman spectroscopy or TERS. The results obtained in this project will be important for applications for which strong local field enhancement factors are crucial for the performance of devices such as near field microscopes or spectroscopy. The optimal design of nanofocusing structures, at which the delivery of electromagnetic energy to the nanometer region is most efficient, will lead to new applications in near field sensors, near field measuring technology, or generation of nanometer sized energy sources. This includes: applications in tip enhanced Raman spectroscopy (TERS); manipulation of nanoparticles and molecules; efficient coupling of optical energy into and out of plasmonic circuits; second harmonic generation in non-linear optics; or delivery of energy to quantum dots, for instance, for quantum computations.
13
Jayasooriya, Jayasooriya Hevavitharanage Aruna Ruwan. "Vulnerability and damage analysis of reinforced concrete framed buildings subjected to near field blast events." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/67925/1/Ruwan_Jayasooriya_Thesis.pdf.
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Terrorists usually target high occupancy iconic and public buildings using vehicle borne incendiary devices in order to claim a maximum number of lives and cause extensive damage to public property. While initial casualties are due to direct shock by the explosion, collapse of structural elements may extensively increase the total figure. Most of these buildings have been or are built without consideration of their vulnerability to such events. Therefore, the vulnerability and residual capacity assessment of buildings to deliberately exploded bombs is important to provide mitigation strategies to protect the buildings' occupants and the property. Explosive loads and their effects on a building have therefore attracted significant attention in the recent past.
Comprehensive and economical design strategies must be developed for future construction. This research investigates the response and damage of reinforced concrete (RC) framed buildings together with their load bearing key structural components to a near field blast event. Finite element method (FEM) based analysis was used to investigate the structural framing system and components for global stability, followed by a rigorous analysis of key structural components for damage evaluation using the codes SAP2000 and LS DYNA respectively. The research involved four important areas in structural engineering. They are blast load determination, numerical modelling with FEM techniques, material performance under high strain rate and non-linear dynamic structural analysis. The response and damage of a RC framed building for different blast load scenarios were investigated. The blast influence region for a two dimensional RC frame was investigated for different load conditions and identified the critical region for each loading case. Two types of design methods are recommended for RC columns to provide superior residual capacities. They are RC columns detailing with multi-layer steel reinforcement cages and a composite columns including a central structural steel core. These are to provide post blast gravity load resisting capacity compared to typical RC column against a catastrophic collapse. Overall, this research broadens the current knowledge of blast and residual capacity analysis of RC framed structures and recommends methods to evaluate and mitigate blast impact on key elements of multi-storey buildings.
14
Tucker, Adam Philip. "Local moment phases in quantum impurity problems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:538d2d83-963e-4a51-81cd-4235e9761da4.
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This thesis considers quantum impurity models that exhibit a quantum phase transition (QPT) between a Fermi liquid strong coupling (SC) phase, and a doubly-degenerate non-Fermi liquid local moment (LM) phase. We focus on what can be said from exact analytic arguments about the LM phase of these models, where the system is characterized by an SU(2) spin degree of freedom in the entire system. Conventional perturbation theory about the non-interacting limit does not hold in the non-Fermi liquid LM phase. We circumvent this problem by reformulating the perturbation theory using a so-called `two self-energy' (TSE) description, where the two self-energies may be expressed as functional derivatives of the Luttinger-Ward functional. One particular paradigmatic model that possesses a QPT between SC and LM phases is the pseudogap Anderson impurity model (PAIM). We use infinite-order perturbation theory in the interaction, U, to self-consistently deduce the exact low-energy forms of both the self-energies and propagators in each of the distinct phases of the model. We analyse the behaviour of the model approaching the QPT from each phase, focusing on the scaling of the zero-field single-particle dynamics using both analytical arguments and detailed numerical renormalization group (NRG) calculations. We also apply two `conserving' approximations to the PAIM. First, second-order self-consistent perturbation theory and second, the fluctuation exchange approximation (FLEX). Within the FLEX approximation we develop a numerical algorithm capable of self-consistently and coherently describing the QPT coming from both distinct phases. Finally, we consider a range of static spin susceptibilities that each probe the underlying QPT in response to coupling to a magnetic field.
15
Ridgers, Christopher Paul. "Magnetic fields and non-local transport in laser plasmas." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/1377.
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The first Vlasov-Fokker-Planck simulations of nanosecond laser-plasma interactions – including the effects of self-consistent magnetic fields and hydrodynamic plasma expansion – will be presented. The coupling between non-locality and magnetic field advection is elucidated. For the largest (initially uniform) magnetic fields externally imposed in recent long-pulse laser gas-jet plasma experiments (12T) a significant degree of cavitation of the B-field will be shown to occur (> 40%) in under 500ps. This is due to the Nernst effect and leads to the re-emergence of non-locality even if the initial value of the magnetic field strength is sufficient to localize transport. Classical transport theory may also break down in such interactions as a result of inverse bremsstrahlung heating. Although non-locality may be suppressed by a large B-field, inverse bremsstrahlung still leads to a highly distorted distribution. Indeed the best fit for a 12T applied field (after 440ps of laser heating) is found to be a super- Gaussian distribution – f0 α e−vm – with m = 3.4. The effects of such a distribution on the transport properties under the influence of magnetic fields are elucidated in the context of laser-plasmas for the first time. In long pulse laser-plasma interactions magnetic fields generated by the thermoelectric (‘∇ne × ∇Te’) mechanism are generally considered dominant. The strength of B-fields generated by this mechanism are affected, and new generation mechanisms are expected, when non-locality is important. Non-local B-field generation is found to be dominant in the interaction of an elliptical laser spot with a nitrogen gas-jet.
16
List, Nanna Holmgaard. "Theoretical Description of Electronic Transitions in Large Molecular Systems in the Optical and X-Ray Regions." Doctoral thesis, Department of Physics, Chemistry and Biology, University of Southern Denmark, Denmark, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201156.
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The size and conformational complexity of proteins and other large systems represent major challenges for today's methods of quantum chemistry.This thesis is centered around the development of new computational tools to gain molecular-level insight into electronic transitions in such systems. To meet this challenge, we focus on the polarizable embedding (PE) model, which takes advantage of the fact that many electronic transitions are localized to a smaller part of the entire system.This motivates a partitioning of the large system into two regions that are treated at different levels of theory:The smaller part directly involved in the electronic process is described using accurate quantum-chemical methods, while the effects of the rest of the system, the environment, are incorporated into the Hamiltonian of the quantum region in an effective manner. This thesis presents extensions of the PE model with theaim of expanding its range of applicability to describe electronic transitions in large molecular systemsin the optical and X-ray regions. The developments cover both improvements with regardto the quantum region as well as the embedding potential representing the environment.Regarding the former, a damped linear response formulation has been implemented to allow for calculations of absorption spectra of large molecular systems acrossthe entire frequency range. A special feature of this development is its abilityto address core excitations that are otherwise not easily accessible.Another important development presented in this thesis is the coupling of the PE model to a multi-configuration self-consistent-field description of the quantum region and its further combination with response theory. In essence, this extends the PE model to the study of electronic transitions in large systems that are prone to static correlation --- a situation that is frequently encountered in biological systems. In addition to the direct environmental effects on the electronic structure of the quantum region, another important component of the description of electronic transitions in large molecular systems is an accurate account of the indirect effects of the environment, i.e., the geometrical distortions in the quantum region imposed by the environment. In thisthesis we have taken the first step toward the inclusion of geometry distortions in the PE frameworkby formulating and implementing molecular gradients for the quantum region. To identify critical points related to the environment description, we perform a theoretical analysis of the PE model starting from a full quantum-mechanicaltreatment of a composite system. Based on this, we present strategies for an accurate yet efficient construction of the embedding potentialcovering both the calculation of ground state and transition properties. The accurate representation of the environment makes it possible to reduce the size of the quantum region without compromising the overall accuracy of the final results. This further enables use of highly accurate quantum-chemical methods despite their unfavorable scaling with the size of the system. Finally, some examples of applications will be presented to demonstrate how the PE model may be applied as a tool to gain insight into and rationalize the factors influencing electronic transitions in large molecular systems of increasing complexity.<br><p>The dissertation was awarded the best PhD thesis prize 2016 by the Danish Academy of Natural Sciences.</p><p></p><p>QC 20170209</p>
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Paula, Netto Tibério de. "Correções de origem quântica para a ação do vácuo e suas aplicações." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/6787.
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Previous issue date: 2017-02-22<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Nesta tese, exploram-se diferentes aspectos e aplicações das teorias gravitacionais com correções quânticas. O texto é dividido em três partes principais. Na primeira parte, são consideradas as soluções linearizadas em diferentes teorias de gravitação com derivadas superiores. O potencial Newtoniano é calculado nos modelos locais, super-renormalizáveis no nível quântico, e mostra-se que a singularidade Newtoniana é cancelada devido a contribuição dos modos massivos extras. Logo depois, o colapso gravitacional de uma pequena massa é estudado na gravitação não-local livre de fantasmas, sendo o principal resultado a ausência da singularidade na solução do campo gravitacional e a possibilidade da não formação do miniburaco negro como resultado do colapso. Na segunda parte, algumas questões sobre a inflação induzida pela anomalia conforme são estudadas. É discutida a possibilidade da transição entre os períodos de inflação estável para instável. É mostrado que esta transição é automática se as correções quânticas nesse período forem desprezadas. Em seguida, considera-se o efeito de termos que violam as simetrias de CPT e Lorentz na inflação induzida pela anomalia conforme. É demonstrado que os novos termos responsáveis por violar essas simetrias não afetam a dinâmica do fator de escala da métrica. Por fim, na terceira parte as correções quânticas para o modelo dos Galileons e para as teorias dos campos massivos tensoriais antissimétricos são obtidas. É mostrado que o propagador da teoria dos Galileons recebe correções quânticas com derivadas superiores e que o teorema de não-renormalização do modelo dos Galileons permanece, de uma maneira generalizada, válido na região das baixas energias. Depois, por meio de cálculos explícitos das correções quânticas semiclássicas não-locais é confirmada a equivalência quântica entre os modelos dos campos tensoriais antissimétricos massivos com a teoria de Proca e com o modelo do campo escalar massivo mínimo.<br>In this thesis, different aspects and applications of gravitational theories with quan-tum corrections are explored. The text is divided into three main parts. In the first part, the linearized solutions in different gravity theories with higher derivatives are considered. The Newtonian potential is calculated in the local models, super-renormalizable at the quantum level, and it is shown that the Newtonian singularity is cancelled due to the contributions of the extra massive modes. Then the gravitational collapse of a small mass is studied in non-local ghost-free gravity, being the main result the absence of singularity in the gravitational field solution and the possibility of non-mini black hole formation as the collapse result. In the second part, some issues about anomaly-induced inflation are studied. It is discussed the possibility of the transition between stable to unstable periods of inflation. It is shown that this transition is automatic if the quantum corrections in this period are neglected. In the following, we consider the effect of CPT and Lorentz-violating terms in the conformal anomaly-induced inflation. It is shown the new terms responsible to violate these symmetries do not affect the dynamics of the metric scale factor. Finally, in the third part, the quantum corrections for the Galileon model and for the theory of the massive antisymmetric tensor fields are obtained. It is shown that the propaga-tor of Galilean theory receives quantum corrections with higher derivatives and that the non-renormalization theorem for Galileon models remains, in a generalized way, valid in the low-energy region. Then, by means of explicit calculations of non-local semiclassical quantum corrections, the quantum equivalence between the massive antisymmetric tensor field models with the Proca theory and minimal massive scalar field model is confirmed.
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Gu, Sijia. "Contribution to broadband local characterization of materials by near-field microwave microscopy." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10175/document.
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Les microscopes champ proche micro-ondes sont des instruments émergents pour la caractérisation de matériaux. Dans ce travail, un microscope champ proche micro-ondes fait maison est d'abord décrit et analysé en termes de résolution et de largeur de bande de fréquences de fonctionnement. Ensuite, il est mis en œuvre pour la caractérisation d'une grande variété de matériaux tels que par exemple des métaux, des semi-conducteurs, des diélectriques, des liquides et des nanomatériaux 2D. Le système intégre un interférométre pour améliorer la sensibilité de la mesure pour des fréquences de fonctionnement couvrant la bande 2-18 GHz. La sensibilité et les différents modes de fonctionnement disponibles (contact, sans contact, environnement liquide) permettent d'adresser une grande variété de domaines d'applications. La résolution latérale obtenue par cet instrument est plus petite de plusieurs ordres de grandeur que la longueur d'onde de fonctionnement, ouvrant ainsi la voie à une caractérisation locale. Les propriétés électromagnétiques des matériaux ont été extraites en utilisant la méthode de perturbation et celle de la ligne de transmission. En particulier, les propriétés diélectriques de solutions salines aqueuses et l’impédance complexe du graphène ont été étudiées dans une large bande de fréquence. Ce microscope champ proche micro-ondes basé sur une méthode interférométrique qui permet une analyse quantitative des propriétés des matériaux de manière non-destructive peut adresser un grand éventail d’applications dans de nombreux domaines scientifiques. Enfin, l’ensemble des résultats montre que potentiellement la microscopie champ proche micro-ondes dispose des atouts pour devenir un outil de métrologie important pour la caractérisation en micro- et nano-électronique<br>Near-field microwave microscopes are emerging instruments for materials characterization. In this work, a home-made near-field microwave microscope is first described and analyzed in terms of resolution performance and frequency band of operation. Then, it is applied to the characterization of a large variety of materials such as metals, semiconductors, dielectrics, liquids and 2D nanomaterials. The system is based on an interferometric technique to improve the measurement sensitivity in the entire frequency range of operation spanning from 2 to 18 GHz. The sensitivity and the different operating modes available (contact, non-contact, liquid environment) allow addressing a large variety of application fields. The instrument allows a sub-wavelength lateral resolution which is more than two orders of magnitude smaller than the operating wavelength, opening the way to a local characterization. The cavity perturbation and transmission line approaches have been used to extract the electromagnetic properties of materials. In particular dielectric properties of saline aqueous solutions and complex impedance of graphene have been investigated in a broad frequency band. It provides a quantitative analysis of material properties in a non-destructive manner to address numerous applications in many scientific fields. Finally, all the results together show that the interferometer-based near-field microwave microscope has the potential to become an important metrology tool for characterizations in micro- and nano-electronics
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Almeida, Uirá Norberto Matos de. "Resolubilidade local de campos vetoriais reais." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-23042014-163412/.
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Nesta dissertação vamos estudar alguns importantes resultados acerca da resolubilidade local de operadores lineares de primeira ordem. Mais especificamente, seja o campo vetorial singular L em \'R POT. n\' e dado por: L = \'\\SIGMA SUP. m\' . INF. j=1\' a IND. j\' (x) \'SUP. \\PARTIAL\' INF. \\PARTIAL x INF. j\'. Esta trabalho dirige-se ao estudo da resolubilidade local de L, isto é, dada f \'PERTENCE A\' \' C POT. INFINITO\' (\'R POT. n\') e dado \'x IND. 0\' \'PERTENCE A\' \'R POT. n queremos encontrar u \'PERTENCE A\' D\'(\'R POT.n \') tal que Lu = f numa vizinhança de \'x INF. 0\'. Será dada atenção especial ao caso em que os coeficientes \'a IND. j\'(x) de L são função lineares. Também, serão apresentados resultados sobre a resolubilidade local da equação Lu = cu + f, sendo c \'PERTENCE A\' \'C POT. INFINITO\' (\'R POT. n\')<br>This dissertation aims to study some important results about local solvability of first order differential operators. Specifically, let L be a singular vector field on \'R POT. n\' given by L = \' \\SIGMA SUP. m INF.j=1\' \'a IND. j(x) \'\\PARTIAL SUP. INF. \\PARTIAL x INF. j\'. This work explore the local solvability of L, that is, given f \'IT BELONGS\' \'C POT. INFINITY\' (\'R POT. n\' and \'x INF. 0\' \'IT BELONGS\' \'R POT. n\' we want to find u \'IT BELONGS\' 2 D\'(\'R POT. n) such that Lu = f in a neighborhood of \'x INF. 0\'. We give special attention to the case where the coefficients \'a IND. j\'(x) are linear. We also present some results about local solvability of the equation Lu = cu + f for c \'IT BELONGS\' \'C POT. INFINITY\' (\'R POT. n\')
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Rosu, Roxana Gabriela. "Parametric approaches for modelling local structure tensor fields with applications to texture analysis." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0102/document.
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Cette thèse porte sur des canevas méthodologiques paramétriques pour la modélisation de champs de tenseurs de structure locaux (TSL) calculés sur des images texturées. Estimé en chaque pixel, le tenseur de structure permet la caractérisation de la géométrie d’une image texturée à travers des mesures d’orientation et d’anisotropie locales. Matrices symétriques semi-définies positives, les tenseurs de structure ne peuvent pas être manipulés avec les outils classiques de la géométrie euclidienne. Deux canevas statistiques riemanniens, reposant respectivement sur les espaces métriques a ne invariant (AI) et log-euclidien (LE), sont étudiés pour leur représentation. Dans chaque cas, un modèle de distribution gaussienne et de mélange associé sont considérés pour une analyse statistique. Des algorithmes d’estimation de leurs paramètres sont proposés ainsi qu’une mesure de dissimilarité. Les modèles statistiques proposés sont tout d’abord considérés pour décrire des champs de TSL calculés sur des images texturées. Les modèles AI et LE sont utilisés pour décrire des distributions marginales de TSL tandis que les modèles LE sont étendus afin de décrire des distributions jointes de TSL et de caractériser des dépendances spatiales et multi-échelles. L’ajustement des modèles théoriques aux distributions empiriques de TSL est évalué de manière expérimentale sur un ensemble de textures composées d’un spectre assez large de motifs structuraux. Les capacités descriptives des modèles statistiques proposés sont ensuite éprouvées à travers deux applications. Une première application concerne la reconnaissance de texture sur des images de télédétection très haute résolution et sur des images de matériaux carbonés issues de la microscopie électronique à transmission haute résolution. Dans la plupart des cas, les performances des approches proposées sont supérieures à celles obtenues par les méthodes de l’état de l’art. Sur l’espace LE, les modèles joints pour la caractérisation des dépendances spatiales au sein d’un champ de TSL améliorent légèrement les résultats des modèles opérant uniquement sur les distributions marginales. La capacité intrinsèque des méthodes basées sur le tenseur de structure à prendre en considération l’invariance à la rotation, requise dans beaucoup d’applications portant sur des textures anisotropes, est également démontrée de manière expérimentale. Une deuxième application concerne la synthèse de champs de TSL. A cet e et, des approches mono-échelle ainsi que des approches pyramidales multi-échelles respectant une hypothèse markovienne sont proposées. Les expériences sont effectuées à la fois sur des champs de TSL simulés et sur des champs de TSL calculés sur des textures réelles. Efficientes dans quelques configurations et démontrant d’un potentiel réel de description des modèles proposés, les expériences menées montrent également une grande sensibilité aux choix des paramètres qui peut s’expliquer par des instabilités d’estimation sur des espaces de grande dimension<br>This thesis proposes and evaluates parametric frameworks for modelling local structure tensor (LST) fields computed on textured images. A texture’s underlying geometry is described in terms of orientation and anisotropy, estimated in each pixel by the LST. Defined as symmetric non-negative definite matrices, LSTs cannot be handled using the classical tools of Euclidean geometry. In this work, two complete Riemannian statistical frameworks are investigated to address the representation of symmetric positive definite matrices. They rely on the a ne-invariant (AI) and log-Euclidean (LE) metric spaces. For each framework, a Gaussian distribution and its corresponding mixture models are considered for statistical modelling. Solutions for parameter estimation are provided and parametric dissimilarity measures between statistical models are proposed as well. The proposed statistical frameworks are first considered for characterising LST fields computed on textured images. Both AI and LE models are first employed to handle marginal LST distributions. Then, LE models are extended to describe joint LST distributions with the purpose of characterising both spatial and multiscale dependencies. The theoretical models’ fit to empirical LST distributions is experimentally assessed for a texture set composed of a large diversity of patterns. The descriptive potential of the proposed statistical models are then assessed in two applications. A first application consists of texture recognition. It deals with very high resolution remote sensing images and carbonaceous material images issued from high resolution transmission electron microscopy technology. The LST statistical modelling based approaches for texture characterisation outperform, in most cases, the state of the art methods. Competitive texture classification performances are obtained when modelling marginal LST distributions on both AI and LE metric spaces. When modelling joint LST distributions, a slight gain in performance is obtained with respect to the case when marginal distributions are modelled. In addition, the LST based methods’ intrinsic ability to address the rotation invariance prerequisite that arises in many classification tasks dealing with anisotropic textures is experimentally validated as well. In contrast, state of the art methods achieve a rather pseudo rotation invariance. A second application concerns LST field synthesis. To this purpose, monoscale and multiscale pyramidal approaches relying on a Markovian hypothesis are developed. Experiments are carried out on toy LST field examples and on real texture LST fields. The successful synthesis results obtained when optimal parameter configurations are employed, are a proof of the real descriptive potential of the proposed statistical models. However, the experiments have also shown a high sensitivity to the parameters’ choice, that may be due to statistical inference limitations in high dimensional spaces
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Jondreville, David. "Quantification de groupes p-adiques et applications aux algèbres d'opérateurs." Thesis, Reims, 2017. http://www.theses.fr/2017REIMS010.
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Cette thèse est consacrée à l'étude des déformations des C*-algèbres munies d'une action de groupe, du point de vue de la quantification équivariante non-formelle, dans le cas non-archimédien. Nous construisons une théorie de déformation des C*-algèbres munies d'une action d'un espace vectoriel de dimension finie sur un corps local non-archimédien de caractéristique différente de 2 ainsi que pour des quotients du groupe affine d'un corps local dont le corps résiduel est de cardinal impair. Par ailleurs, nous construisons des familles de 2-cocycles unitaires afin de déformer des groupes quantiques localement compacts agissant sur ces C*-algèbres déformées<br>This thesis is devoted to the study of deformation of C*-algebras endowed with a group action, from the perspective of non-formal equivariant quantization, in the non-Archimedean setting. We construct a deformation theory of C*-algebras endowed with an action of a finite dimensional vector space over a non-Archimedean local field of characteristic different from 2 and for quotients of the affine group of a local field whose residue field has cardinality not divisible by 2. Moreover, we construct families of dual unitary 2-cocycles in order to deform locally compact quantum groups acting on these deformed C*-algebras
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Daly, Marwa El. "Challenges and potentials of channeling local philanthropy towards development and aocial justice and the role of waqf (Islamic and Arab-civic endowments) in building community foundations." Doctoral thesis, Humboldt-Universität zu Berlin, Philosophische Fakultät III, 2012. http://dx.doi.org/10.18452/16511.
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Diese Arbeit bietet eine solide theoretische Grundlage zu Philanthropie und religiös motivierten Spendenaktivitäten und deren Einfluss auf Wohltätigkeitstrends, Entwicklungszusammenarbeit und einer auf dem Gedanken der sozialen Gerechtigkeit beruhenden Philanthropie. Untersucht werden dafür die Strukturen religiös motivierte Spenden, für die in der islamischen Tradition die Begriffe „zakat“, „Waqf“ oder im Plural auch „awqaf-“ oder „Sadaqa“ verwendet werden, der christliche Begriff dafür lautet „tithes“ oder „ushour“. Aufbauend auf diesem theoretischen Rahmenwerk analysiert die qualitative und quantitative Feldstudie auf nationaler Ebene, wie die ägyptische Öffentlichkeit Philanthropie, soziale Gerechtigkeit, Menschenrechte, Spenden, Freiwilligenarbeit und andere Konzepte des zivilgesellschaftlichen Engagements wahrnimmt. Um eine umfassende und repräsentative Datengrundlage zu erhalten, wurden 2000 Haushalte, 200 zivilgesellschaftliche Organisationen erfasst, sowie Spender, Empfänger, religiöse Wohltäter und andere Akteure interviewt. Die so gewonnen Erkenntnisse lassen aussagekräftige Aufschlüsse über philanthropische Trends zu. Erstmals wird so auch eine finanzielle Einschätzung und Bewertung der Aktivitäten im lokalen Wohltätigkeitsbereich möglich, die sich auf mehr als eine Billion US-Dollar beziffern lassen. Die Erhebung weist nach, dass gemessen an den Pro-Kopf-Aufwendungen die privaten Spendenaktivitäten weitaus wichtiger sind als auswärtige wirtschaftliche Hilfe für Ägypten. Das wiederum lässt Rückschlüsse zu, welche Bedeutung lokale Wohltätigkeit erlangen kann, wenn sie richtig gesteuert wird und nicht wie bislang oft im Teufelskreis von ad-hoc-Spenden oder Hilfen von Privatperson an Privatperson gefangen ist. Die Studie stellt außerdem eine Verbindung her zwischen lokalen Wohltätigkeits-Mechanismen, die meist auf religiösen und kulturellen Werten beruhen, und modernen Strukturen, wie etwa Gemeinde-Stiftungen oder Gemeinde-„waqf“, innerhalb derer die Spenden eine nachhaltige Veränderung bewirken können. Daher bietet diese Arbeit also eine umfassende wissenschaftliche Grundlage, die nicht nur ein besseres Verständnis, sondern auch den nachhaltiger Aus- und Aufbau lokaler Wohltätigkeitsstrukturen in Ägypten ermöglicht. Zentral ist dabei vor allem die Rolle lokaler, individueller Spenden, die beispielsweise für Stiftungen auf der Gemeindeebene eingesetzt, wesentlich zu einer nachhaltigen Entwicklung beitragen könnten – und das nicht nur in Ägypten, sondern in der gesamten arabischen Region. Als konkretes Ergebnis dieser Arbeit, wurde ein innovatives Modell entwickelt, dass neben den wissenschaftlichen Daten das Konzept der „waqf“ berücksichtigt. Der Wissenschaftlerin und einem engagierten Vorstand ist es auf dieser Grundlage gelungen, die Waqfeyat al Maadi Community Foundation (WMCF) zu gründen, die nicht nur ein Modell für eine Bürgerstiftung ist, sondern auch das tradierte Konzept der „waqf“ als praktikable und verbürgte Wohlstätigkeitsstruktur sinnvoll weiterentwickelt.<br>This work provides a solid theoretical base on philanthropy, religious giving (Islamic zakat, ‘ushour, Waqf -plural: awqaf-, Sadaqa and Christian tithes or ‘ushour), and their implications on giving trends, development work, social justice philanthropy. The field study (quantitative and qualitative) that supports the theoretical framework reflects at a national level the Egyptian public’s perceptions on philanthropy, social justice, human rights, giving and volunteering and other concepts that determine the peoples’ civic engagement. The statistics cover 2000 households, 200 Civil Society Organizations distributed all over Egypt and interviews donors, recipients, religious people and other stakeholders. The numbers reflect philanthropic trends and for the first time provide a monetary estimate of local philanthropy of over USD 1 Billion annually. The survey proves that the per capita share of philanthropy outweighs the per capita share of foreign economic assistance to Egypt, which implies the significance of local giving if properly channeled, and not as it is actually consumed in the vicious circle of ad-hoc, person to person charity. In addition, the study relates local giving mechanisms derived from religion and culture to modern actual structures, like community foundations or community waqf that could bring about sustainable change in the communities. In sum, the work provides a comprehensive scientific base to help understand- and build on local philanthropy in Egypt. It explores the role that local individual giving could play in achieving sustainable development and building a new wave of community foundations not only in Egypt but in the Arab region at large. As a tangible result of this thesis, an innovative model that revives the concept of waqf and builds on the study’s results was created by the researcher and a dedicated board of trustees who succeeded in establishing Waqfeyat al Maadi Community Foundation (WMCF) that not only introduces the community foundation model to Egypt, but revives and modernizes the waqf as a practical authentic philanthropic structure.
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Tunguz, Bojan. "Non-local Gauge Field Theory /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3250337.
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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.<br>Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1042. Adviser: Yoshitsugu Oono. Includes bibliographical references (leaves 105-108) Available on microfilm from Pro Quest Information and Learning.
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Li, Gang [Verfasser]. "Non-local correlations within dynamical mean field theory / vorgelegt von Li, Gang." 2009. http://d-nb.info/993556701/34.
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Antony, Daniel Sanju. "Performance Analysis of Non Local Means Algorithm using Hardware Accelerators." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/2932.
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Image De-noising forms an integral part of image processing. It is used as a standalone algorithm for improving the quality of the image obtained through camera as well as a starting stage for image processing applications like face recognition, super resolution etc. Non Local Means (NL-Means) and Bilateral Filter are two computationally complex de-noising algorithms which could provide good de-noising results. Due to its computational complexity, the real time applications associated with these letters are limited.
In this thesis, we propose the use of hardware accelerators such as GPU (Graphics Processing Units) and FPGA (Field Programmable Gate Arrays) to speed up the filter execution and efficiently implement using them. GPU based implementation of these letters is carried out using Open Computing Language (Open CL). The basic objective of this research is to perform high speed de-noising without compromising on the quality. Here we implement a basic NL-Means filter, a Fast NL-Means filter, and Bilateral filter using Gauss Polynomial decomposition on GPU. We also propose a modification to the existing NL-Means algorithm and Gauss Polynomial Bilateral filter. Instead of Gaussian Spatial Kernel used in standard algorithm, Box Spatial kernel is introduced to improve the speed of execution of the algorithm. This research work is a step forward towards making the real time implementation of these algorithms possible. It has been found from results that the NL-Means implementation on GPU using Open CL is about 25x faster than regular CPU based implementation for larger images (1024x1024). For Fast NL-Means, GPU based implementation is about 90x faster than CPU implementation. Even with the improved execution time, the embedded system application of the NL-Means is limited due to the power and thermal restrictions of the GPU device. In order to create a low power and faster implementation, we have implemented the algorithm on FPGA. FPGAs are reconfigurable devices and enable us to create a custom architecture for the parallel execution of the algorithm. It was found that the execution time for smaller images (256x256) is about 200x faster than CPU implementation and about 25x faster than GPU execution. Moreover the power requirements of the FPGA design of the algorithm (0.53W) is much less compared to CPU(30W) and GPU(200W).
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Antony, Daniel Sanju. "Performance Analysis of Non Local Means Algorithm using Hardware Accelerators." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2932.
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Image De-noising forms an integral part of image processing. It is used as a standalone algorithm for improving the quality of the image obtained through camera as well as a starting stage for image processing applications like face recognition, super resolution etc. Non Local Means (NL-Means) and Bilateral Filter are two computationally complex de-noising algorithms which could provide good de-noising results. Due to its computational complexity, the real time applications associated with these letters are limited.
In this thesis, we propose the use of hardware accelerators such as GPU (Graphics Processing Units) and FPGA (Field Programmable Gate Arrays) to speed up the filter execution and efficiently implement using them. GPU based implementation of these letters is carried out using Open Computing Language (Open CL). The basic objective of this research is to perform high speed de-noising without compromising on the quality. Here we implement a basic NL-Means filter, a Fast NL-Means filter, and Bilateral filter using Gauss Polynomial decomposition on GPU. We also propose a modification to the existing NL-Means algorithm and Gauss Polynomial Bilateral filter. Instead of Gaussian Spatial Kernel used in standard algorithm, Box Spatial kernel is introduced to improve the speed of execution of the algorithm. This research work is a step forward towards making the real time implementation of these algorithms possible. It has been found from results that the NL-Means implementation on GPU using Open CL is about 25x faster than regular CPU based implementation for larger images (1024x1024). For Fast NL-Means, GPU based implementation is about 90x faster than CPU implementation. Even with the improved execution time, the embedded system application of the NL-Means is limited due to the power and thermal restrictions of the GPU device. In order to create a low power and faster implementation, we have implemented the algorithm on FPGA. FPGAs are reconfigurable devices and enable us to create a custom architecture for the parallel execution of the algorithm. It was found that the execution time for smaller images (256x256) is about 200x faster than CPU implementation and about 25x faster than GPU execution. Moreover the power requirements of the FPGA design of the algorithm (0.53W) is much less compared to CPU(30W) and GPU(200W).
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Deepu, S. P. "Non-Local Continuum Models for Damage in Solids and Delamination of Composites." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4206.
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The focus of the thesis is on developing new damage models for brittle materials and using these to study delamination of composite structures. Chapter 1 gives an introductory literature review in order to motivate the work undertaken in the chapters to follow. Chapter 2 deals with a new micropolar damage model for delamination in composites. By combining phase field theory and peridynamics, Chapter 3 develops a new formalism to study damage in brittle materials under dynamic loading. Chapter 4 exploits and extends this idea for modelling delamination of composites. An extended chapter-wise summary of the contributions in the thesis is provided below.
In Chapter 2, a micropolar cohesive damage model for delamination of composites is proposed. The main idea is to embed micropolarity, which brings in an added layer of kinematics through the micro-rotation degrees of freedom within a continuum model to account for the micro-structural effects during delamination. The resulting cohesive model, described through a modified traction separation law, includes micro-rotational jumps in addition to displacement jumps across the interface. The incorporation of micro-rotation requires the model to be supplemented with physically relevant material length scale parameters, whose effects during delamination in modes I and II are brought forth using numerical simulations appropriately supported by experimental evidences.
In Chapter 3, we attempt at reformulating the phase field theory within the framework of peridynamics (PD) to arrive at a non-local continuum damage model. This obtains a better criterion for bond breaking in PD, marking a departure from the inherently ad-hoc bond-stretch-based or bond-energy-based conditions and thus allowing the model to simulate fragmentation which a phase field model cannot by itself accomplish. Moreover, posed within the PD setup, the integral equation for the phase field eases the smoothness restrictions on the field variable. Taking advantages of both the worlds, the scheme thus offers a better computational approach to problems involving cracks or discontinuities. Starting with Hamilton’s principle, an equation of the Ginzburg-Landau type with dissipative correction is arrived at as a model for the phase field evolution. A constitutive correspondence route is followed to incorporate
classical constitutive relations within our PD model. Numerical simulations of dynamic crack propagation (including branching) and the Kalthoff-Winkler experiment are also provided. To demonstrate the natural ability of the model to prevent interpenetration, a mode II delamination simulation is presented. A brief discussion on the convergence of PD equations to classical theory is provided in the Appendix B.
In Chapter 4, we extend and exploit the phase field based PD damage model, developed in Chapter 3, for studying delamination of composites. Utilizing the phase field augmented PD framework, our idea is to model the interfacial cohesive damage through degradation functions and the fracture or fragmentation through the critical energy release rate. Our model eliminates the conventional traction-separation law (TSL) that is known to result in the popular cohesive zone model (CZM). In the process, the approach potentially addresses some limitations of the existing techniques, which make use of an empirical interaction among different modes of loading (e.g. mode I, mode II etc.). By regarding delamination under different loading conditions as problems that differ only in their boundary conditions, our approach provides for a more general scheme for tracking delamination. Our proposal thus accords no special treatment to the different modes and can handle general spatial locations of weaker interface layers. With no special crack tracking algorithms or additional ad-hoc criteria for crack propagation, considerable computational simplicity also accrues. The approach can tackle cases where cracks may propagate even in the bulk material body. The new bond breaking criterion that we employ replaces the ad-hocism inherent in bond-stretch-based or bond-energy-based conditions. Using numerical simulations on mode I (double cantilever beam test), mode II (end loaded split and end notched flexure tests) and mixed mode (fixed ratio mixed mode test) delamination cases, the model is validated against relevant experimental observations. Simulations on modified mixed mode bending test and multiple layer delamination test are also presented.
The thesis is wound up in Chapter 5 with a summary of accomplished research and some suggestions for future research.
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Liu, Lulu. "Nonlinear Preconditioning and its Application in Multicomponent Problems." Diss., 2015. http://hdl.handle.net/10754/583375.
Full textAbstract:
The Multiplicative Schwarz Preconditioned Inexact Newton (MSPIN) algorithm is presented as a complement to Additive Schwarz Preconditioned Inexact Newton (ASPIN). At an algebraic level, ASPIN and MSPIN are variants of the same strategy to improve the convergence of systems with unbalanced nonlinearities; however, they have natural complementarity in practice. MSPIN is naturally based on partitioning of degrees of freedom in a nonlinear PDE system by field type rather than by subdomain, where a modest factor of concurrency can be sacrificed for physically motivated convergence robustness. ASPIN, originally introduced for decompositions into subdomains, is natural for high concurrency and reduction of global synchronization.
The ASPIN framework, as an option for the outermost solver, successfully handles strong nonlinearities in computational fluid dynamics, but is barely explored for the highly nonlinear models of complex multiphase flow with capillarity, heterogeneity, and complex geometry. In this dissertation, the fully implicit ASPIN method is demonstrated for a finite volume discretization based on incompressible two-phase reservoir simulators in the presence of capillary forces and gravity. Numerical experiments show that the number of global nonlinear iterations is not only scalable with respect to the number of processors, but also significantly reduced compared with the standard inexact Newton method with a backtracking technique. Moreover, the
ASPIN method, in contrast with the IMPES method, saves overall execution time because of the savings in timestep size.
We consider the additive and multiplicative types of inexact Newton algorithms in the field-split context, and we augment the classical convergence theory of ASPIN for the multiplicative case. Moreover, we provide the convergence analysis of the MSPIN algorithm. Under suitable assumptions, it is shown that MSPIN is locally convergent, and desired superlinear or even quadratic convergence can be obtained when the forcing terms are picked suitably. Numerical experiments show that MSPIN can be significantly more robust than Newton methods based on global linearizations, and that MSPIN can be more robust than ASPIN, and maintain fast convergence even for challenging problems, such as high-Reynolds number Navier-Stokes equations.
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Yokono, Jerry Jun, and Tomaso Poggio. "Evaluation of sets of oriented and non-oriented receptive fields as local descriptors." 2004. http://hdl.handle.net/1721.1/30454.
Full textAbstract:
Local descriptors are increasingly used for the task of object recognition because of their perceived robustness with respect to occlusions and to global geometrical deformations. We propose a performance criterion for a local descriptor based on the tradeoff between selectivity and invariance. In this paper, we evaluate several local descriptors with respect to selectivity and invariance. The descriptors that we evaluated are Gaussian derivatives up to the third order, gray image patches, and Laplacian-based descriptors with either three scales or one scale filters. We compare selectivity and invariance to several affine changes such as rotation, scale, brightness, and viewpoint. Comparisons have been made keeping the dimensionality of the descriptors roughly constant. The overall results indicate a good performance by the descriptor based on a set of oriented Gaussian filters. It is interesting that oriented receptive fields similar to the Gaussian derivatives as well as receptive fields similar to the Laplacian are found in primate visual cortex.
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Mercer, Christine Joy. "'Being there' when one's spouse is hospitalised in a non-local tertiary centre : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Nursing at Massey University, Palmerston North, New Zealand." 2006. http://hdl.handle.net/10179/1458.
Full textAbstract:
Illness that requires hospitalisation is a potential cause of anxiety for the entire family. Furthermore, increases in technology and specialisation of hospital services have resulted in increasing numbers of patients being transferred to centralised tertiary hospitals. There is limited international and national literature that explores the phenomenon of having one's spouse hospitalised in non-local tertiary centres. Therefore, this study was conducted with the aim of exploring the experiences of those whose spouses were hospitalised in non-local tertiary settings. Understanding of the experiences of 14 people affected by such hospitalisations was underpinned by a Heideggerian phenomenological perspective. Three major themes emerged from this study. Those who have their spouse hospitalised in non-local tertiary settings spend time waiting; a time best described as being-in-suspense. Despite being-in-suspense the research participants adjusted to their understanding of the situation; a period of time interpreted as fitting being out-of-town into being-in-the-world. The final theme that emerged from this study is that there were times when the research participants perceived that they were alone, unable to support or be supported by their spouses: being with and without others. Overall the findings of this research indicate that those whose spouses were hospitalised in a non-local tertiary centre lived day by day, with little or no social support, awaiting outcomes over which they had limited control. The worst potential outcome for these individuals would be that of the spouse's death in the non-local centre. When the outcomes of the non-local hospitalisation could be predicted, the events of living day by day were manageable. It also emerged from conducting this study that in living day by day, the supporting spouse dealt with the circumstances by being focussed on the temporality of the present and a vision of a positive future. However, their spouses were not always able to conceive the future in such a positive way. Nurses and other health professionals must remain cognisant of the fact that while they are familiar with the everydayness of non-local hospitalisations, [abstract incomplete].
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Veselý, Vítek. "Fyzika nebodových objektů v silných gravitačních polích." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-405471.
Full textAbstract:
We study several different models of extended bodies in gravitational fields. Firstly, we revisit the glider model of a dumbbell-like oscillating body. We develop an independent scheme to integrate the equations of motion. We study the radial fall of a Newtonian spring, calculate the position shifts of the spring and find the critical value of the spring constant which cannot overcome the tidal forces. We argue that the relativistic glider model is unphysical due to its behaviour in the critical regions. Secondly, we show that Dixon's theory of extended bodies predicts a geodesic motion of the centre of mass in maximally symmetric spacetimes. We prove that a system of test particles can be described by a conserved stress-energy tensor and we evaluate the position shifts of the glider model in the maximally symmetric spacetimes, showing its disagreement with Dixon's theory. We thus conclude again that the glider model must be rejected. And thirdly, we study a model of an extended body consisting of interacting particles, which is in accord with Dixon's theory. We calculate the position shifts for this model and show that the model does not predict any measurable swimming effect. Finally, we estimate the numerical error of the calculation by finding the position shifts of the model in maximally symmetric...