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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Estudo e análise do coeficiente de absorção acústico do compósito da fibra de cana

Outa, Roberto [UNESP] 25 July 2014 (has links) (PDF)
Made available in DSpace on 2015-01-26T13:21:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-25Bitstream added on 2015-01-26T13:30:45Z : No. of bitstreams: 1 000802231.pdf: 1542226 bytes, checksum: cfd78188537d9a6f5bb97f5dcb5d1aec (MD5) / O objetivo motivacional deste trabalho é estudar a possibilidade de desenvolvimento de um material a base de bagaço de cana com um maior valor agregado, propondo assim, outra função e/ou utilização para o bagaço da cana de açúcar. Para isso, foi desenvolvido um aglomerado de fibra de cana (compósito) com diferentes proporções de fibra de cana e aglutinante, e posteriormente foram estudadas algumas características acústicas destes diferentes compósitos, avaliando assim, o potencial de uso da fibra como material de absorção acústica. Os coeficientes de absorção acústica do aglomerado foram estimados com base na teoria e conceitos de acústica utilizando o tubo de impedância, tendo como base a norma ISO10534-1(1996). Os resultados obtidos do coeficiente de absorção acústica dos compósitos analisados mostraram que a fibra da cana pode ser utilizada como um material de absorção acústica, dependendo da composição do compósito, o mesmo se mostrou equivalente a alguns materiais do mercado de absorvedores acústico / The motivational goal of this work is to study the possibility of developing a material basis of bagasse with a higher added value, thus suggesting another function and / or use for bagasse from sugar cane. For this, we developed a cluster of sugarcane (composite) with different proportions of sugar and binder fiber and fiber were subsequently studied some acoustic characteristics of different composites, thus assessing the potential use of fiber as sound absorption material. The sound absorption coefficients of the cluster were estimated based on the theory and concepts of acoustic, using the impedance tube, based on the standard ISO10534-1 (1996). The results of the sound absorption coefficient of the analysis showed that the composite fiber rod can be used as an acoustic absorption material, depending on the composition of the composite, it was equivalent to some of the noise absorbing materials market
352

Estruturações melódico-harmônicas nos 50 Ponteios de Camargo Guarnieri / Melodic and harmonic structures in the 50 Ponteios of Camargo Guarnieri

Pereira, Gesiel Vilarubia [UNESP] 30 June 2017 (has links)
Submitted by Gesiel Vilarubia Pereira (35345734801) on 2017-08-23T13:24:32Z No. of bitstreams: 1 Dissertação - Gesiel Vilarubia Pereira.pdf: 134882582 bytes, checksum: 1b452379542030a7180799844b4e877a (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-08-23T18:10:15Z (GMT) No. of bitstreams: 1 pereira_gv_me_ia.pdf: 134882582 bytes, checksum: 1b452379542030a7180799844b4e877a (MD5) / Made available in DSpace on 2017-08-23T18:10:15Z (GMT). No. of bitstreams: 1 pereira_gv_me_ia.pdf: 134882582 bytes, checksum: 1b452379542030a7180799844b4e877a (MD5) Previous issue date: 2017-06-30 / Tendo como objeto de estudo os 50 Ponteios para piano de Camargo Guarnieri, este trabalho se concentra na análise de suas estruturações melódicas e harmônicas, almejando compreender aspectos estruturais da poética do compositor neste ciclo de peças. Apresenta-se, inicialmente, um diálogo entre as transformações sofridas pela escritura melódico-harmônica de Guarnieri durante o período de composição desta coleção e uma contextualização histórico-estilística, na qual são focalizadas, principalmente, suas buscas por um nacionalismo influenciado por Mário de Andrade e suas experiências com diferentes idiomas harmônicos. Propõe-se, ainda como texto preparatório para as análises, uma classificação textural dos 50 Ponteios e, ainda, a verificação de algumas constâncias formais dentro desta coleção. Nos capítulos seguintes, esta dissertação se direciona para a verificação das escolhas dos materiais presentes na construção das melodias e harmonias e se estende sobre observação dos procedimentos composicionais característicos de Guarnieri – sua poética. A partir desta investigação analítica, constatamos, nos Ponteios e em outras obras do compositor, a recorrência de um motivo melódico o qual denominamos Motivo Guarnieri. Na dimensão harmônica, chamou-nos a atenção a reincidência de uma determinada estrutura harmônica simétrica, utilizada com função Dominante nos momentos cadenciais, além do cuidado, por parte do compositor, em usar estruturas simétricas nos contextos escalares, harmônicos e formais. Sempre que possível, as análises foram permeadas por diálogos estabelecidos com pesquisadores da obra de Guarnieri e pela observação das relações entre suas decisões composicionais e seu posicionamento estético, diretamente influenciado pelo livro Ensaio sobre a música brasileira, de Mário de Andrade. / The aim of this work is to study the 50 Piano Ponteios of Camargo Guarnieri, focusing on the analysis of their melodic and harmonic structures, seeking to understand the structural aspects of the composer's poetics in this cycle of pieces. We initially examine the transformations incurred by Guarnieri's melodic-harmonic writing in the period that this collection was composed, and a produce a historical-stylistic contextualization. This contextualization focuses on the Brazilan nationalism which was influenced by Brazilian philosopher and critic Mário de Andrade, and Guarnieri’s experiences with different harmonic languages. In preparation for the analysis, a textural classification of the 50 Ponteios is performed, as well as a verification of some formal consistencies within this collection. The dissertation is also directed to the examination of the choices of the materials present in the construction of the melodies and harmonies, and extends to the observation of the compositional procedures characteristic of Guarnieri – in other words, his poetics. From this analytical investigation we can observe, in the Ponteios and in other works by this composer, the recurrence of a melodic motif which we call The Guarnieri Motive. In terms of harmony, we are struck by the recurrence of a specific symmetrical harmonic structure, used as dominant function in cadential moments. We may also verify the care the composer took to use symmetrical structures in scalar, harmonic and formal contexts. Whenever possible, the analysis was permeated by dialogues established with researchers on Guarnieri’s work, and by the observation of the relationship between Guarnieri’s compositional decisions and his aesthetic opinion, as influenced directly by the book Ensaio sobre a música brasileira by Mário de Andrade.
353

ExistÃncia e unicidade para os problemas de Dirichlet e Neumann sobre um domÃnio com fronteira suave / Existence and uniqueness for the Dirichlet and Neumann problems on a domain with smooth boundary

CÃcero Fagner Alves da Silva 08 July 2010 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Seja Ω um domÃnio fixado em Rn com fronteira S de classe C2 e denote Ω′ = Rn Ω. Ambos Ω e Ω′ nÃo necessariamente conexos. Nessas condiÃÃes, pretendemos resolver os problemas de Dirichlet e Neumann. No intuito da resoluÃÃo dos problemas citados, faremos um estudo daTeoria de Fredholm (operadores compactos), bem como da transformada de Kelvin, harmonicidade no infinito e dos potenciais de camada. / Let Ω be a fixed domain in Rn with boundary S of class C2 and denote Ω′ = Rn Ω. Both Ω and Ω′ not necessarily connected. Under these conditions, we intend to solve the problems of Dirichlet and Neumann. In order to overcome the mentioned the problems, we will study the Fredholm theory (compact operators), the Kelvin transformed, harmonicity in the infinite and potential of the layer.
354

Homotopy sheaves on manifolds and applications to spaces of smooth embeddings

Boavida de Brito, Pedro January 2014 (has links)
This thesis explores connections between homotopy sheaves, manifold calculus of functors and operad theory. We argue that there is a deep overlap between these, and as evidence we give a new operadic description of the homotopy theoretical obstructions to deforming a smooth immersion into a smooth embedding. We then discuss an application which improves on some aspects of recent results of Arone-Turchin and Dwyer-Hess concerning spaces of long knots and high-dimensional variants. Along the way, we define fibrewise complete Segal spaces, a mild generalisation of Rezk's notion of complete Segal spaces. Also in the context of Segal spaces, we define right fibrations and prove a Grothendieck construction theorem for presheaves with values in spaces. Finally, we prove a result of independent interest which states that weakly k-reduced operads (those with contractible space of operations in arity j ? k) can be strictified when k = 0, 1.
355

Polarisation controlled quasi-phase matching of high harmonic generation

Liu, Lewis January 2014 (has links)
This thesis focuses on the development of high harmonic generation (HHG) by using polarisation controlled quasi-phase matching QPM as well as related topics. A new class of QPM techniques called polarisation-controlled QPM is introduced where linear or circlar birefringence enables the modulation of the driving field's polarisation state called polarisation-beating QPM (PBQPM) for linear birefringence and optical rotation QPM (ORQPM) for circular birefringence respectively. PBQPM uses a linear birefringence to modulate periodically the driving pulse between linear and circular/elliptical polarisation states. Because elliptical or circular polarisation of the driving pulse suppresses harmonic generation, by appropriately matching the beat length of the driving field's polarisation state to the coherence length of the harmonic generation, QPM can be achieved. In the second technique, ORQPM, propagation of the driving radiation in a system exhibiting circular birefringence causes its plane of polarisation to rotate; by appropriately matching the period of rotation to the coherence length, it is possible to avoid destructive interference of the generated radiation. Not only does ORQPM have similar enhancements as true-phase matching, it is also the first proposed QPM source for circularly polarised high harmonics. The importance of phase modulation in QPM, especially relating to modebeating in hollow-core waveguides where harmonics is being generated are also explored theoretically. Based on this, a novel technique for analyzing random phase matching using a continuous phase-diffusion treatment has been developed; theoretical analytical models are shown to produce excellent agreement with simulations. It is further shown that random phase matching may be responsible for additional broadening of the high harmonic spectrum, especially at higher harmonic orders. Because mode and polarisation control is central to polarisation-controlled QPM, four waveguide mode decomposition techniques from single shot CCD data have been developed. The extraction of phase and coupling coefficients are demonstrated experimentally. A novel analytical general solution for the phase introduced by a phase-only spatial light modulator to generate a given far-field phase and amplitude was developed. The solution was demonstrated experimentally and shown to enable excellent control of the far-field amplitude and phase. Finally, circular and linear birefringent waveguides were explored. Analytic solutions to rectangular birefringent hollow-core waveguides were developed and some initial demonstration experiments were performed.
356

Probing Collective Multi-electron Effects with Few Cycle Laser Pulses

Shiner, Andrew January 2013 (has links)
High Harmonic Generation (HHG) enables the production of bursts of coherent soft x-rays with attosecond pulse duration. This process arrises from the nonlinear interaction between intense infrared laser pulses and an ionizing gas medium. Soft x-ray photons are used for spectroscopy of inner-shell electron correlation and exchange processes, and the availability of attosecond pulse durations will enable these processes to be resolved on their natural time scales. The maximum or cutoff photon energy in HHG increases with both the intensity as well as the wavelength of the driving laser. It is highly desirable to increase the harmonic cutoff as this will allow for the generation of shorter attosecond pulses, as well as HHG spectroscopy of increasingly energetic electronic transitions. While the harmonic cutoff increases with laser wavelength, there is a corresponding decrease in harmonic yield. The first part of this thesis describes the experimental measurement of the wavelength scaling of HHG efficiency, which we report as lambda^(-6.3) in xenon, and lambda^(-6.5) in krypton. To increase the HHG cutoff, we have developed a 1.8 um source, with stable carrier envelope phase and a pulse duration of <2 optical cycles. The 1.8 um wavelength allowed for a significant increase in the harmonic cutoff compared to equivalent 800 nm sources, while still maintaing reasonable harmonic yield. By focusing this source into neon we have produced 400 eV harmonics that extend into the x-ray water window. In addition to providing a source of photons for a secondary target, the HHG spectrum caries the signature of the electronic structure of the generating medium. In krypton we observed a Cooper minimum at 85 eV, showing that photoionization cross sections can be measured with HHG. Measurements in xenon lead to the first clear observation of electron correlation effects during HHG, which manifest as a broad peak in the HHG spectrum centred at 100 eV. This thesis also describes several improvements to the HHG experiment including the development of an ionization detector for measuring laser intensity, as well as an investigation into the role of laser mode quality on HHG phase matching and efficiency.
357

Steady State Analysis of Nonlinear Circuits using the Harmonic Balance on GPU

Bandali, Bardia January 2013 (has links)
This thesis describes a new approach to accelerate the simulation of the steady-state response of nonlinear circuits using the Harmonic Balance (HB) technique. The approach presented in this work focuses on direct factorization of the sparse Jacobian matrix of the HB nonlinear equations using a Graphics Processing Unit (GPU) platform. This approach exploits the heterogeneous structure of the Jacobian matrix. The computational core of the proposed approach is based on developing a block-wise version of the KLU factorization algorithm, where scalar arithmetic operations are replaced by block-aware matrix operations. For a large number of harmonics, or excitation tones, or both the Block-KLU (BKLU) approach effectively raises the ratio of floating-point operations to other operations and, therefore, becomes an ideal vehicle for implementation on a GPU-based platform. Motivated by this fact, a GPU-based Hybrid Block KLU framework is developed to implement the BKLU. The proposed approach in this thesis is named Hybrid-BKLU. The Hybrid-BKLU is implemented in two parts, on the host CPU and on the graphic card’s GPU, using the OpenCL heterogeneous parallel programming language. To show the efficiency of the Hybrid-BKLU approach, its performance is compared with BKLU approach performing HB analysis on several test circuits. The Hybrid-BKLU approach yields speedup by up to 89 times over conventional BKLU on CPU.
358

Dynamic analysis of cage rotor induction motor using harmonic field analysis and coupling inductances method

Al Sayari, Naji Mohammed Awn sulaiman January 2011 (has links)
The work presented in this thesis involves the development of a new analytical method for predicting the transient behaviour of squirrel cage induction motors subjected to pulsating mechanical loads such as a reciprocating compressor. The objective of this project is to develop analysis that will better inform the subsequent design method for determining the rating of industrial induction motors driving an oscillatory load. The analytical approach used to determine the transient response of the motor is based upon the harmonic coupling inductance method which is capable of accommodating any stator winding arrangement used in industrial motor designs. The analytical work described in this thesis includes the response of an induction motor subjected to a general oscillating load in terms of the damping and synchronous torque components. These torque components can be used to determine the additional system inertia required to limit the motor speed and current oscillations to predetermined levels. The work further identifies the motor-load natural resonant frequency and demonstrates the potential issues when driving a general oscillatory load at or close to this frequency. The analytical model was cross-checked using software modelling in Matlab for an industrial squirrel cage induction motor driving a selection of compressor loads. The simulation results were finally correlated with a detailed experimental validation in the laboratory using a squirrel cage induction motor connected to a permanent magnet synchronous motor controlled electronically to simulate general oscillatory load.
359

Nonlinear and Quantum Optics Near Nanoparticles

Dhayal, Suman 12 1900 (has links)
We study the behavior of electric fields in and around dielectric and metal nanoparticles, and prepare the ground for their applications to a variety of systems viz. photovoltaics, imaging and detection techniques, and molecular spectroscopy. We exploit the property of nanoparticles being able to focus the radiation field into small regions and study some of the interesting nonlinear, and quantum coherence and interference phenomena near them. The traditional approach to study the nonlinear light-matter interactions involves the use of the slowly varying amplitude approximation (SVAA) as it simplifies the theoretical analysis. However, SVVA cannot be used for systems which are of the order of the wavelength of the light. We use the exact solutions of the Maxwell's equations to obtain the fields created due to metal and dielectric nanoparticles, and study nonlinear and quantum optical phenomena near these nanoparticles. We begin with the theoretical description of the electromagnetic fields created due to the nonlinear wavemixing process, namely, second-order nonlinearity in an nonlinear sphere. The phase-matching condition has been revisited in such particles and we found that it is not satisfied in the sphere. We have suggested a way to obtain optimal conditions for any type and size of material medium. We have also studied the modifications of the electromagnetic fields in a collection of nanoparticles due to strong near field nonlinear interactions using the generalized Mie theory for the case of many particles applicable in photovoltaics (PV). We also consider quantum coherence phenomena such as modification of dark states, stimulated Raman adiabatic passage (STIRAP), optical pumping in $4$-level atoms near nanoparticles by using rotating wave approximation to describe the Hamiltonian of the atomic system. We also considered the behavior of atomic and the averaged atomic polarization in $7$-level atoms near nanoparticles. This could be used as a prototype to study any $n-$level atomic system experimentally in the presence of ensembles of quantum emitters. In the last chapter, we suggested a variant of a pulse-shaping technique applicable in stimulated Raman spectroscopy (SRS) for detection of atoms and molecules in multiscattering media. We used discrete-dipole approximation to obtain the fields created by the nanoparticles.
360

An Optimality-Theoretic Analysis of the Japanese Passive / 日本語の受動態の最適性理論による分析

Rudy, TOET 23 March 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(文学) / 甲第22169号 / 文博第816号 / 新制||文||684(附属図書館) / 京都大学大学院文学研究科行動文化学専攻 / (主査)教授 定延 利之, 教授 吉田 豊, 准教授 千田 俊太郎 / 学位規則第4条第1項該当 / Doctor of Letters / Kyoto University / DGAM

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