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Dissertations / Theses on the topic 'CIRCULAR HARMONICS'
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1
Quellmalz, Michael. "Reconstructing Functions on the Sphere from Circular Means." Universitätsverlag Chemnitz, 2019. https://monarch.qucosa.de/id/qucosa%3A38406.
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The present thesis considers the problem of reconstructing a function f that is defined on the d-dimensional unit sphere from its mean values along hyperplane sections. In case of the two-dimensional sphere, these plane sections are circles. In many tomographic applications, however, only limited data is available. Therefore, one is interested in the reconstruction of the function f from its mean values with respect to only some subfamily of all hyperplane sections of the sphere. Compared with the full data case, the limited data problem is more challenging and raises several questions. The first one is the injectivity, i.e., can any function be uniquely reconstructed from the available data? Further issues are the stability of the reconstruction, which is closely connected with a description of the range, as well as the demand for actual inversion methods or algorithms.
We provide a detailed coverage and answers of these questions for different families of hyperplane sections of the sphere such as vertical slices, sections with hyperplanes through a common point and also incomplete great circles. Such reconstruction problems arise in various practical applications like Compton camera imaging, magnetic resonance imaging, photoacoustic tomography, Radar imaging or seismic imaging. Furthermore, we apply our findings about spherical means to the cone-beam transform and prove its singular value decomposition.Die vorliegende Arbeit beschäftigt sich mit dem Problem der Rekonstruktion einer Funktion f, die auf der d-dimensionalen Einheitssphäre definiert ist, anhand ihrer Mittelwerte entlang von Schnitten mit Hyperebenen. Im Fall d=2 sind diese Schnitte genau die Kreise auf der Sphäre. In vielen tomografischen Anwendungen sind aber nur eingeschränkte Daten verfügbar. Deshalb besteht das Interesse an der Rekonstruktion der Funktion f nur anhand der Mittelwerte bestimmter Familien von Hyperebenen-Schnitten der Sphäre. Verglichen mit dem Fall vollständiger Daten birgt dieses Problem mehrere Herausforderungen und Fragen. Die erste ist die Injektivität, also können alle Funktionen anhand der gegebenen Daten eindeutig rekonstruiert werden? Weitere Punkte sind die die Frage nach der Stabilität der Rekonstruktion, welche eng mit einer Beschreibung der Bildmenge verbunden ist, sowie der praktische Bedarf an Rekonstruktionsmethoden und -algorithmen. Diese Arbeit gibt einen detaillierten Überblick und Antworten auf diese Fragen für verschiedene Familien von Hyperebenen-Schnitten, angefangen von vertikalen Schnitten über Schnitte mit Hyperebenen durch einen festen Punkt sowie Kreisbögen. Solche Rekonstruktionsprobleme treten in diversen Anwendungen auf wie der Bildgebung mittels Compton-Kamera, Magnetresonanztomografie, fotoakustischen Tomografie, Radar-Bildgebung sowie der Tomografie seismischer Wellen. Weiterhin nutzen wir unsere Ergebnisse über sphärische Mittelwerte, um eine Singulärwertzerlegung für die Kegelstrahltomografie zu zeigen.
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Khoshniat, Ali. "A Linearly and Circularly Polarized Active Integrated Antenna." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/881.
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This thesis work presents a new harmonic suppression technique for microstrip patch antennas. Harmonic suppression in active integrated antennas is known as an effective method to improve the efficiency of amplifiers in transmitter side. In the proposed design, the antenna works as the radiating element and, at the same time, as the tuning load for the amplifier circuit that is directly matched to the antenna. The proposed active antenna architecture is easy to fabricate and is symmetric, so it can be conveniently mass-produced and designed to have circular polarization, which is preferred in many applications such as satellite communications.
The antenna simulations were performed using Ansoft High Frequency System Simulator (HFSS) and all amplifier design steps were simulated by Advanced Design System (ADS). The final prototypes of the linearly polarized active integrated antenna and the circularly polarized active integrated antenna were fabricated using a circuit board milling machine. The antenna radiation pattern was measured inside Utah State University's anechoic chamber and the results were satisfactory. Power measurements for the amplifiers' performance were carried out inside the chamber and calculated by using the Friis transmission equation. It is seen that a significant improvement in the efficiency is achieved compared to the reference antenna without harmonic suppression.
Based on the success in the single element active antenna design, the thesis also presents a feasibility of applying the active integrated antenna in array configuration, in particular, in scanning array design to yield a low-profile, low-cost alternative to the parabolic antenna transmitter of satellite communication systems.
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Salahifar, Raydin. "Analysis of Pipeline Systems Under Harmonic Forces." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19820.
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Starting with tensor calculus and the variational form of the Hamiltonian functional, a generalized theory is formulated for doubly curved thin shells. The formulation avoids geometric approximations commonly adopted in other formulations. The theory is then specialized for cylindrical and toroidal shells as special cases, both of interest in the modeling of straight and elbow segments of pipeline systems. Since the treatment avoids geometric approximations, the cylindrical shell theory is believed to be more accurate than others reported in the literature. By adopting a set of consistent geometric approximations, the present theory is shown to revert to the well known Flugge shell theory. Another set of consistent geometric approximations is shown to lead to the Donnell-Mushtari-Vlasov (DMV) theory. A general closed form solution of the theory is developed for cylinders under general harmonic loads. The solution is then used to formulate a family of exact shape functions which are subsequently used to formulate a super-convergent finite element. The formulation efficiently and accurately captures ovalization, warping, radial expansion, and other shell behavioural modes under general static or harmonic forces either in-phase or out-of-phase. Comparisons with shell solutions available in Abaqus demonstrate the validity of the formulation and the accuracy of its predictions. The generalized thin shell theory is then specialized for toroidal shells. Consistent sets of approximations lead to three simplified theories for toroidal shells. The first set of approximations has lead to a theory comparable to that of Sanders while the second set of approximation has lead to a theory nearly identical to the DMV theory for toroidal shells. A closed form solution is then obtained for the governing equation. Exact shape functions are then developed and subsequently used to formulate a finite element. Comparisons with Abaqus solutions show the validity of the formulation for short elbow segments under a variety of loading conditions. Because of their efficiency, the finite elements developed are particularly suited for the analysis of long pipeline systems.
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Santos, Nalzira Medalha dos. "Os processos circulares como instrumento para a investigação dos elementos que contribuem para a relação harmoniosa entre professor e aluno." Universidade de Taubaté, 2015. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=788.
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This work is related to a research about teacher-student relationship developed with seventeen teachers from a public school, from a country town in São Paulo State. The aims are: from the educator point of view, investigate which elements contribute to a harmonious relationship between teacher and student and inquire, from the same point of view, which are the obstacles that challenge the current teacher-student relationship. For that, the circular process technique was used as a methodology, where some questions related to the teacher and student relationship were proposed, they were recorded and then transcribed for further analysis, according to the model of Bardin. The theoretical basis was mainly from Vygotsky concerning to: the close relation between cognition and affectivity, to the importance of the environment as a source for the individual development, and still considering the relation between thinking and language, the meaning of words, being all this together with the concept of perezhivanie, fundamental inputs for this research. According to the analysis of the collected answers, reported by the subjects of the research about their emotional experiences relating to the memories of the elements that characterize the good relationship between teacher and student, it was observed that the subjects value the human and emotional aspects, but do not stop to consider the aspects of technical and pedagogical character, which also represent the appreciation and respect of teachers by students, resulting in personal appreciation that enables to create affective bonds. As for the difficulties and challenges of teacher-student relationship today, a large percentage of answers showed factors outside the school (lack of values in the family and society) as the main responsible. These responses encourage a reflection on how to solve this problem. In the view of the surveyed teachers, the found alternatives take again the importance of human and affective aspects. It is believed that this work will contribute to the reflection on the harmonious coexistence between teachers and students, as this relationship becomes a key factor in the educational process.Este trabalho diz respeito a uma pesquisa sobre a relação professor-aluno realizada com dezessete professores de uma escola municipal de uma cidade do interior paulista. Os objetivos são: investigar, segundo o ponto de vista docente, quais elementos contribuem para uma relação harmoniosa entre professor e aluno e inquirir, segundo o mesmo ponto de vista, as dificuldades que caracterizam os desafios da atual relação professor-aluno. Para tanto, utilizou-se como metodologia a técnica do Processo Circular em que foram propostas algumas questões referentes à relação professor-aluno, as quais foram gravadas e posteriormente transcritas, a fim de serem analisadas segundo os constructos da análise de conteúdo de Bardin. A fundamentação teórica apoiou-se sobretudo em Vygotsky no que diz respeito à indissociação entre cognição e afetividade, ao papel do ambiente como fonte de desenvolvimento, abordando ainda a relação entre pensamento e linguagem, o sentido da palavra, sendo estes, juntamente com o conceito de perezhivanie, aportes fundamentais para esta pesquisa. De acordo com a análise das respostas colhidas a partir do relato das experiências emocionais dos sujeitos de pesquisa referentes às memórias acerca dos elementos que caracterizam a boa relação entre professor-aluno, foi possível observar que os sujeitos valorizam os aspectos humanos e afetivos, mas não deixam de considerar os aspectos de caráter técnico-pedagógico, os quais também representam o apreço e o respeito do professor pelo aluno, traduzindo-se em valorização pessoal, capaz de criar vínculos afetivos. Quanto às dificuldades e desafios da relação professor-aluno nos dias atuais, um grande percentual de respostas apresentou os fatores externos à escola (falta de valores na família e na sociedade) como os principais responsáveis. Essas respostas incentivam uma reflexão acerca de como resolver essa problemática. Na visão dos professores pesquisados, as alternativas encontradas retomam a importância de aspectos humanos e afetivos. Acredita-se que esse trabalho poderá contribuir para a reflexão sobre a convivência harmoniosa entre professores e alunos, uma vez que tal relação torna-se um fator fundamental no processo educativo.
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Herald, Christopher R., and Christopher R. Herald. "The Advent of an Artist-Composer Movement Exemplified by the Works of Saxophonists Colin Stetson, Evan Parker, and Contemporaries." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625662.
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Arising out of the avant-garde jazz tradition, a particular genre of solo saxophone music has emerged that combines stylistic attributes of avant-garde jazz and improvisation with minimalism, and is dependent on circular breathing, harmonic manipulation, and other techniques. To distinguish the music and the saxophonists and composers associated with it I have referred to this genre as "post avant-garde." With its roots ultimately in avant-garde jazz of the 1960s, this genre arose through the solo improvisation work of Evan Parker from the 1970s to present, and the music has since been an influence on the work of Colin Stetson and other artists, as well as composers including Gordon Fitzell and Alex Mincek. This document examines a previously unacknowledged but distinct genre of solo saxophone music, as well as the music of associated artists and composers.
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Kumar, Bhunesh. "Design of Harmonic Filters for Renewable Energy Applications." Thesis, Högskolan på Gotland, Institutionen för kultur, energi och miljö, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hgo:diva-1862.
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Harmonics are created by non-linear devices connected to the power system. Power system harmonics are multiples of the fundamental power system frequency and these harmonic frequencies can create distorted voltages and currents. Distortion of voltages and currents can affect the power system adversely causing power quality problems. Therefore, estimation of harmonics is of high importance for efficiency of the power system network. The problem of harmonic loss evaluation is of growing importance for renewable power system industry by impacting the operating costs and the useful life of the system components. Non-linear devices such as power electronics converters can inject harmonics alternating currents (AC) in the electrical power system. The number of sensitive loads that require ideal sinusoidal supply voltage for their proper operation has been increasing. To maintain the quality limits proposed by standards to protect the sensitive loads, it is necessary to include some form of filtering device to the power system. Harmonics also increases overall reactive power demanded by equivalent load. Filters have been devised to achieve an optimal control strategy for harmonic alleviation problems. To achieve an acceptable distortion, increase the power quality and to reduce the harmonics hence several three phase filter banks are used and connected in parallel. In this thesis, high order harmonics cases have been suppressed by employing variants of Butterworth, Chebyshev and Cauer filters. MATLAB/SIMULINK wind farm model was used to generate and analyze the different harmonics magnitude and frequency. High voltage direct current (HVDC) lines for an electrical grid that is more than50km far away wind farm generation plant was investigated for harmonics. These HVDC lines are also used in offshore wind farm plant. Investigated three-phase harmonics filters are shunt elements that are used in power systems for decreasing voltage distortion and for correcting the power factor. Renewable energy sources are not the stable source of energy generation like wind, solar and tidal e.t.c. Though they are secondary sources of generation and hard to connect with electrical grid. In near future the technique is to use the wave digital filter (WDF) or circulator-tree wave digital filter (CTWDF) for the renewable energy application can be employed to mitigate the harmonics. These WDF and CTWDF can b eused in HVDC lines and smart grid applications. A preliminary analysis is conducted for such a study.
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Bakhshi, Shashwat. "Numerical Analysis to Study the Effect of Sag and Non-circular Whirl Orbits on the Damping Performance of a Squeeze Film Damper." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522420027908978.
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David, Anca Hélène. "L'évolution du droit de l'environnement de l'Union européenne : un outil de mise en place de l'économie verte et circulaire." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB177.
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L'évolution du droit de l'environnement de l'Union européenne a conduit au développement d'un objectif nouveau qui vise à promouvoir l'éco-innovation et les modèles d'entreprise verts, afin de mettre en place une économie verte et circulaire. Ce nouvel objectif a eu des conséquences sur sa forme et son contenu. En effet, la forme du droit de l'Union européenne en matière d'environnement est dominée par des directives-cadres et présente une flexibilité accrue, tandis que son contenu intègre de nouveaux modèles d'entreprise, notamment le modèle d'entreprise circulaire. La transition vers une économie verte a également des conséquences sur la manière dont les États membres transposent le droit de l'environnement de l'Union européenne. Le processus de transposition est devenu un vecteur de commercialisation de l'éco-innovation sur le marché européen, associant des acteurs nouveaux à la prise de décision, à savoir : les éco-entreprises, les laboratoires de recherche et d'innovation, les pôles de compétitivité, les entreprises du numérique ou les investisseurs providentielsThe evolution of the European Union environmental law has led to the development of a new goal that aims to promote eco-innovation and green business models, in order to create a green and circular economy. This new goal had consequences on its form and content. The form of the European Union environmental law is dominated by framework directives and presents increased flexibility, while its content integrates new business models, particularly the circular business model. Furthermore, the transition to a green economy has an impact on how Member States transpose the European Union environmental law. The transposition process has become a vector of commercializing eco-innovation on the European market, and brings together new stakeholders in the decision-making process, namely: green companies, research and innovation laboratories, clusters, digital companies or business angels
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Harouni, Zied. "Conception et caractérisation d’une Rectenna à double polarisation circulaire à 2.45 GHz." Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1026/document.
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Les travaux présentés dans ce mémoire s'inscrivent dans la thématique de la transmission d'énergie sans fil, appliquée à l'alimentation à distance de capteurs, de réseaux de capteurs et d'actionneurs à faible consommation. Cette étude porte sur la conception, la caractérisation, et la mesure d'un circuit Rectenna (Rectifying antenna) à double polarisation circulaire à 2.45 GHz, compact et à rendement de conversion RF-DC optimisé. Un outil d'analyse globale basé sur la méthode itérative a été développé et exploité pour valider la faisabilité de cette analyse. La diode Schottky a été modélisée en utilisant une impédance de surface. La rectenna à double polarisation circulaire, réalisée en technologie micro-ruban, a été validée expérimentalement. Elle est caractérisée par la rejection de la 2ème harmonique et une possibilité de recevoir les deux sens de polarisation LHCP et RHCP par l'intermédiaire de 2 accès. Le rendement mesuré avec une densité de puissance de 0.525 mW/cm² est de l'ordre de 63%, tandis que la tension DC obtenue aux bornes d'une charge optimale de 1.6 kohm est de 2.82 VThe work presented in this thesis is within the subject of wireless power transmission, power applied to the remote sensors, networks of sensors and actuators with low power consumption. This study focuses on the design, characterization, and measurement of a rectenna circuit (rectifying antenna) with dual circular polarization at 2.45 GHz, and optimisation of the conversion efficiency. A global analysis tool, based on the iterative method was developed and used to validate the feasibility of this concept by this method. The Schottky diode was modeled using surface impedance. The dual circular polarization rectenna with microstrip technology has been optimized and characterized experimentally operating at 2.45 GHz. It includes the property of harmonic rejections. Two accesses can receive either direction LHCP or RHCP sense. The conversion efficiency of 63% has been measured with a power density of 0.525 mW/cm². A DC voltage of 2.82V was measured across an optimum load of 1.6 kohm
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Chen, Zhangchi. "Differential invariants of parabolic surfaces and of CR hypersurfaces; Directed harmonic currents near non-hyperbolic linearized singularities; Hartogs’ type extension of holomorphic line bundles; (Non-)invertible circulant matrices On differential invariants of parabolic surfaces A counterexample to Hartogs’ type extension of holomorphic line bundles Directed harmonic currents near non-hyperbolic linearized singularities Affine Homogeneous Surfaces with Hessian rank 2 and Algebras of Differential Invariants On nonsingularity of circulant matrices." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASM005.
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La thèse se compose de 6 articles. (1) Nous calculons les générateurs des SA₃(ℝ)-invariants pour les surfaces paraboliques. (2) Nous calculons les invariants rigides relatifs pour les hypersurfaces rigides 2-non-dégénérées de rang de Levi constant 1 dans ℂ³: V₀, I₀, Q₀ ayant 11, 52, 824 monômes au numérateur. (3) Nous organisons tous les modèles affinement homogènes non-dégénérés dans ℂ³ en branches inéquivalentes. (4) Pour un courant harmonique dirigé autour d'une singularité linéarisée non-hyperbolique qui ne charge pas les séparatrices triviales dont l'extension triviale à travers 0 est ddc-fermée, nous démontrons que le nombre de Lelong en 0 est : 4.1) strictement positif si λ>0 ; 4.2) nul si λ est rationnel et négatif ; 4.3) nul si λ est négatif et si T est invariant sous l'action d'un sous-groupe cofini du groupe de monodromie. (5) Nous construisons des fibrés holomorphes en droites en toute dimension n>=2 non-prolongeables au sens de Hartogs. (6) Nous montrons que les matrices circulantes ayant k entrées 1 et k+1 entrées 0 dans leur première rangée sont toujours non singulières lorsque 2k+1 est soit une puissance d'un nombre premier, soit un produit de deux nombres premiers distincts. Pour tout autre entier 2k+1, nous exhibons une matrice circulante singulièreThe thesis consists of 6 papers. (1) We calculate the generators of SA₃(ℝ)-invariants for parabolic surfaces. (2) We calculate rigid relative invariants for rigid constant Levi-rank 1 and 2-non-degenerate hypersurfaces in ℂ³: V₀, I₀, Q₀ having 11, 52, 824 monomials in their numerators. (3) We organize all affinely homogeneous nondegenerate surfaces in ℂ³ in inequivalent branches. (4) For a directed harmonic current near a non-hyperbolic linearized singularity which does not give mass to any of the trivial separatrices and whose trivial extension across 0 is ddc-closed, we show that the Lelong number at 0 is: 4.1) strictly positive if the eigenvalue λ>0; 4.2) zero if λ is a negative rational number; 4.3) zero if λ<0 and if T is invariant under the action of some cofinite subgroup of the monodromy group. (5) We construct non-extendable, in the sense of Hartogs, holomorphic line bundles in any dimension n>=2. (6) We show that circulant matrices having k ones and k+1 zeros in the first row are always nonsingular when 2k+1 is either a power of a prime, or a product of two distinct primes. For any other integer 2k+1 we exhibit a singular circulant matrix
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Ferré, Amelie. "Etude des dynamiques moléculaires sondées par générations d'harmoniques d'ordres élevés." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0165/document.
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Grâce à ses propriétés (cohérence, brillance, durée), le rayonnement XUV femtoseconde produit par génération d'harmoniques d'ordre élevé est utilisé comme un processus de sonde pour l'étude de dynamiques atomiques et moléculaires, avec une bonne résolution spatiale et temporelle (femtoseconde voire attoseconde). Ainsi, des dynamiques rotationnelles ont été résolues sur des petits systèmes moléculaires (N2, CO2). Les travaux de cette thèse ont consisté à étendre les méthodes de spectroscopie harmoniques et les appliquer à des systèmes moléculaires complexes d'intérêt femtochimique. Parmi elles, nous présenterons la génération d'harmoniques à deux sources, le réseau transitoire d'excitation ou encore la génération d'harmoniques à deux couleurs. Ces techniques nous ont permis de résoudre des dynamiques femtosecondes dans N2O4 et SF6. La HHG est aussi utilisée comme source de rayonnement XUV, en jouant le rôle d'impulsion pompe lors d'expériences de type pompe-sonde. Cette approche a été utilisée pour l'étude du dichroïsme circulaire de photoélectrons de molécules chirales ionisées par un champ XUV harmonique de polarisation quasi circulaire. Nous nous attarderons à détailler la découverte de cette nouvelle source XUV femtoseconde de polarisation quasi circulaireHigh harmonic generation (HHG) spectroscopy has proven to be a promisingtool (like probe in pump-probe experiments) in revealing the atomic and molecular dynamicswith the potential for subangstrom spatial resolution and subfemtosecond temporalresolution. Then, rotational dynamics have been resolved on small molecular systems (N2,CO2). This thesis looks to extending HHG spectroscopy methods to probe the structureand the dynamic of complex molecular systems. We will describe the two sources highharmonic generation, the transient grating of excitation and the two-color high harmonicgeneration. We enable to resolve the femtosecond nuclear dynamics in N2O4 and SF6. HHGis also used like a XUV radiation source, playing the role of pump pulse. This approach hasbeen used for the study of photoelectron circular dichroism. An XUV harmonic field witha quasi-circular polarization ionizes chiral molecules. In this manuscript, we will developthis new femtosecond XUV and quasi circular polarization radiation
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RICCI, ALESSANDRO MARIA. "Superconducting magnets for future accelerators." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1002038.
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The Large Hadron Collider (LHC) at CERN, which is now in operation for ten years, is not only the largest and more powerful particle accelerator in the world, but also constitutes one of the greatest applications of the superconducting magnet technology. Nevertheless, the need to increase both the luminosity in the next future and the energy in more far future is demanding for the developments of new and more challenging superconducting magnets generating higher magnetic fields. Presently all laboratories worldwide involved in the superconducting magnet technology for accelerators are performing R&D activities aimed to the development of a high field superconducting magnet (16 T) for the Future Circular Collider, an accelerator for 50-TeV energy protons (7 times higher than the energy of the LHC beams). The needed technology demands for the use of superconducting material (Niobium Tin) well-known but of difficult application requiring a considerable development before it can be used for 16-T magnet. It is also under study the possible use of cables based on high critical temperature superconductors (HTS), which are even more difficult and have never been used in accelerators.
The design of the superconducting magnets for accelerators is closely related to the physics of the accelerator. In particular, the optics of the beams is determined by the quality of the magnetic field controlled by dipoles, quadrupoles and higher-order correctors. To a greater extent than existing magnets, the optimization of a magnetic design for the dipoles of the Future Circular Collider, for energies of 100 TeV in the center of mass, has many critical aspects partly related to the intrinsic limitations of superconducting cables (critical fields and currents) and partly to the need to develop stable geometric layouts with respect to geometric variations (mechanical deformation or manufacturing tolerances).
This thesis is focused on the optimization of the field quality for the magnets in the twin-coil configuration (for FCC as for LHC the two openings of the dipoles that curve the proton beams circulating in the opposite direction are assembled in a single cold mass). For this class of magnets, the magnetic cross-talk between the apertures presents considerable complications considering that in a dipole the components of higher-order multipoles must be at the most of the order of 10^-4 with respect to the main dipole field. We have developed analytical methodologies, complemented with numerical analyzes, to minimize magnetic cross-talk through suitable asymmetrical configurations. We have applied these methodologies in the various studies carried out for the development of magnets for the Future Circular Collider contributing to finalize a design, which has been presented as the baseline of an European project funded within H2020 framework, named EuroCirCol. We have also applied the developed methods for studying possible improvements to the present design of the recombination dipoles (called D2) for the high luminosity upgrade of LHC. These are NbTi magnets with a strong cross-talk between the two apertures and are under construction at ASG Superconductors in Genova with a design developed at INFN Genova. At the same time, we have developed the 3D electromagnetic models of both magnet classes. In particular, we have been responsible for the 3D electromagnetic simulations of the EuroCirCol magnet. Finally, we have helped to develop a preliminary design of the FCC recombination dipoles (called DARD), which have required a completely different approach with respect to the D2 magnets for LHC.
The thesis is structured in two main sections with five chapters. The first section (including three chapters) reports the theoretical background and the developed methods. The second section (two further chapters) reports the design activities of the magnets for the high luminosity upgrade of LHC and for FCC.
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Harroue, Benjamin. "Approche bayésienne pour la sélection de modèles : application à la restauration d’image." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0127.
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L’inversion consiste à reconstruire des objets d’intérêt à partir de données acquises au travers d’un système d’observation. Dans ces travaux, nous nous penchons sur la déconvolution d’image. Les données observées constituent une version dégradée de l’objet, altéré par le système (flou et bruit). A cause de la perte d’informations engendrée, le problème devient alors mal conditionné. Une solution est de régulariser dans un cadre bayésien : en se basant sur des modèles, on introduit de l’information a priori sur les inconnues. Se posent alors les questions suivantes : comment comparer les modèles candidats et choisir le meilleur ? Sur quel critère faut-il s’appuyer ? A quelles caractéristiques ou quantités doit-on se fier ? Ces travaux présentent une méthode de comparaison et de sélection automatique de modèles, fondée sur la théorie de la décision bayésienne. La démarche consiste à sélectionner le modèle qui maximise la probabilité a posteriori. Pour calculer ces dernières, on a besoin de connaître une quantité primordiale : l’évidence. Elle s’obtient en marginalisant la loi jointe par rapport aux inconnus : l’image et les hyperparamètres. Les dépendances complexes entre les variables et la grande dimension de l’image rendent le calcul analytique de l’intégrale impossible. On a donc recours à des méthodes numériques. Dans cette première étude, on s’intéresse au cas gaussien circulant. Cela permet, d’une part, d’avoir une expression analytique de l’intégrale sur l’image, et d’autre part, de faciliter la manipulation des matrices de covariances. Plusieurs méthodes sont mises en œuvre comme l’algorithme du Chib couplé à une chaîne de Gibbs, les power posteriors, ou encore la moyenne harmonique. Les méthodes sont ensuite comparées pour déterminer lesquelles sont les plus adéquates au problème dela restauration d’imageInversing main goal is about reconstructing objects from data. Here, we focus on the special case of image restauration in convolution problems. The data are acquired through a altering observation system and additionnaly distorted by errors. The problem becomes ill-posed due to the loss of information. One way to tackle it is to exploit Bayesian approach in order to regularize the problem. Introducing prior information about the unknown quantities osset the loss, and it relies on stochastic models. We have to test all the candidate models, in order to select the best one. But some questions remain : how do you choose the best model? Which features or quantities should we rely on ? In this work, we propose a method to automatically compare and choose the model, based on Bayesion decision theory : objectively compare the models based on their posterior probabilities. These probabilities directly depend on the marginal likelihood or “evidence” of the models. The evidence comes from the marginalization of the jointe law according to the unknow image and the unknow hyperparameters. This a difficult integral calculation because of the complex dependancies between the quantities and the high dimension of the image. That way, we have to work with computationnal methods and approximations. There are several methods on the test stand as Harmonic Mean, Laplace method, discrete integration, Chib from Gibbs approximation or the power posteriors. Comparing is those methods is significative step to determine which ones are the most competent in image restauration. As a first lead of research, we focus on the family of Gaussian models with circulant covariance matrices to lower some difficulties
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Yeung, Carman. "Investigation of Linear and Nonlinear Torsional Guided Waves in Hollow Circular Cylinders for Damage Detection." Thesis, 2021. http://hdl.handle.net/2440/130216.
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Non-destructive testing plays an important role in structural health monitoring. One of the promising options is the use of guided wave for damage detection in engineering applications, such as pipeline and truss system. Common types of damage in the structures include cracks and corrosion. Guided wave is sensitive to cracks up to micro scale. Long range inspection is the other benefit of using guided wave. The overall aim of this thesis is to present a systematic investigation of guided wave in pipe-like structures to gain physical insights into linear and nonlinear features associated with torsional guided wave interaction with damage.
This thesis includes a number of published and prepared journal papers under the same topic. The overview of linear and nonlinear guided wave, and guided wave mixing is introduced in Chapter 1. A computational model using one-dimensional time-domain spectral finite element with cracked element is presented in Chapter 2. This chapter mainly focuses on linear features of guided wave, such as scattering and mode conversion phenomena. The results show that the proposed cracked model has good agreement between the experimental results and three-dimensional (3D) finite element (FE) simulations.
Nonlinear guided wave is highly sensitive to early stage of micro cracks. Material nonlinearity is one of the nonlinear phenomena in the presence of the micro cracks. It can induce higher-order harmonics of guided wave. Guided wave mixing is the advanced version of nonlinear guided wave since the generation of combinational harmonics at sum and difference frequencies can minimise the effect due to the nonlinearity generated by equipment. Chapter 3 analyses the nonlinear characteristics of two interacting fundamental torsional guided wave modes numerically and experimentally. Chapter 4 and Chapter 5 are the extension parts based on the work in Chapter 3 since pipe-like structures are commonly used in many circumstances, for example embedded pipes and pre-stressed hollow structures. Comprehensive studies in this thesis can gain more understanding for the real applications. In Chapter 4, a 3D FE embedded pipe model with the implementation of nonlinear strain energy function is established to simulate the energy leakage of guided wave propagation due to the existence of soil media. The use of 3D laser scanning system receives guided wave signals from the surface of the pipe for verification. Both numerical and experimental results indicate a significant decline in the interested harmonics at mixed frequency and single frequency. On the other hand, acoustoelastic effect is studied in Chapter 5. A series of case studies are carried out to observe the group velocity change with respect to different levels of loading. The nonlinear features, such as combinational harmonics and second harmonics, are also investigated numerically and experimentally.Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2020
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Liao, Haw-Ting, and 廖浩廷. "Fingerprint recognition with circular harmonic function." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/27449301449281025513.
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Huang, Jen-Ting, and 黃任廷. "Isolated, Circularly-Polarized, High Harmonics Generation." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/f7tyru.
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HUANG, SHENG-YANG, and 黃勝暘. "Microstrip-Fed Circular Ring Slot Antennas with Wideband Harmonic Suppression." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q7wcns.
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碩士逢甲大學
電機工程學系
106
Recently, it is a prerequisite requirement for hand-held communication products to possess the advantages such as light in weight, compact size and low manufacturing cost. To satisfy these requirements, a single structure design that comprised of an antenna integrated with the front-end circuit of the communication system is presently attracting many attentions. However, high order harmonic modes excited by the antenna can cause electromagnetic interference (EMI) problems on the active circuit, which lead to degrading the performances of the system. Hence, the common solution to solve this problem is to use low-pass or band-pass filter. However, this method will increase the circuit size, manufacture cost, and insertion loss. To resolve these disadvantages, antenna design with harmonic suppression is now an attractive topic of research interest. This thesis is divided into two parts, the first part presents a wide band harmonic suppression circular ring slot antenna that operate in the 2.45 GHz wireless local area network (WLAN) band. Here, a novel stepped impedance resonator (SIR) structure as a low-pass filter and the open stubs (OS) as a band-stop filter are integrated into the circular ring slot antenna, so that it can suppress unwanted high order harmonic modes (return losses < 3 dB) within the frequencies range from 3 to 20 GHz. Also, it is well known the conventional ring slot antenna is a half wavelength resonator whereas the SIR structure is not only regarded a LPF but also can reduce the size of antenna about 15 % by its electrical characteristic. In the second part of this thesis, a triple-band circular ring slot antenna with wideband harmonic suppression is proposed. It is noteworthy that this triple-band circular ring slot antenna with wideband harmonic suppression design has no effect on the fundamental resonate mode with etching extra slots, so that can operate in the 2.4 GHz, 5.2 GHz and 5.8 GHz WLAN application.
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Yo, Tzong-Chee, and 尤宗旗. "The Wireless PoweringCharging System with Harmonic Rejection and Circular Polarization Rectenna." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45529877410711633048.
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博士國立成功大學
電機工程學系碩博士班
96
In this dissertation, a RF power charging methodology is developed to provide ultimate power supply of wireless sensors in long term operation with rechargeable battery. Based on the FCC (Federal Communication Commission) regulation of the limited permissible exposure radiation density for public, the battery recharging procedure is accomplished by directly connecting to the rectenna without an additional voltage regulator. To achieve this, the input voltage promoting techniques are adopted by combining voltage transformation and voltage booster to overcome the high potential barrier of 4.2V Li-ion battery; also, the input impedance of rectifier while loading the battery is analyzed according to the output DC current for efficiency optimization. After that, to simplify the design procedure of the rectenna, the development of the circular polarization and harmonic rejection circular microstrip antenna is presented here. Such kind of the antenna is especially suitable for the rectifying antenna (rectenna) and active integrated antenna (AIA) to eliminate harmonic suppression filter. Hence, a novel rectenna using the compact circularly polarized (CP) patch antenna with RF-to-DC power conversion part at 2.45 GHz is introduced, in which the unbalanced slots structure is adopted for size reduction and 2nd harmonic rejection. To contribute a rectenna for RF power conversion, the back side of the CP antenna is the doubler rectifier circuit with 3rd order harmonic rejection radial stub for efficiency optimization and harmonic power re-radiation elimination. The adopted CP antenna built on low cost FR-4 substrate has measured 3.1dBic CP gain, bandwidth of 137 MHz (10 dB return loss) and 30 MHz CP bandwidth (3 dB axial ratio). By up to 3rd order harmonic rejection, the RF-to-DC conversion efficiency would reach 53% and 75% with 1 KΩ resistor load under ANSI/IEEE uncontrolled and controlled RF human exposure limit, respectively. In addition, the implantable rectenna (rectifying antenna) used for wireless charging lithium-ion (Li-ion) battery in biomedical implants is proposed in MICS band (402-405MHz) with power reception interface of developed implantable antenna. By the proposed methodology for input impedance based on output DC current, the potential barrier of Li-ion battery is successfully overcome for recharging. Ignoring regulators of the rectified DC voltage, the DC power can supply large enough DC voltage (>4.2V) for charging lithium-ion battery with optimized RF-to-DC conversion efficiency (76.2%) and the average efficiency of 75% from 3.7 to 4.2V. Hence, the bio-implant can prolong its operation life by wireless charging as communicating with external reader by the proposed implantable rectenna.
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SHEM, HOU-TING, and 沈厚廷. "Finite Element Analysis for Double-Circular-Arc Stress Harmonic Drive With Helical Gear." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9u486d.
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碩士國立臺北科技大學
製造科技研究所
107
Harmonic Drive is important in modern invention. The common tooth type is spur gear in Harmonic Drive industry at present. By many studies, the helical gear is smoother, longer life, heavier load, and less noise than the spur gear. And it is used widely in high-precision requirements. It can extend the transmission life, increase load capacity and reduce the number of replacement, that the harmonic gear combined with helical gear. This paper uses the SOLIDWORK to construct the model and used ANSYS to analyze the Von Mises stress and strain, and set the Young's modulus of the material to be E=210GPa. Then, the double-arc tooth Harmonic Drive is combined with the helical angle to analyze Von Mises stress and strain at different helical angles, observe the stress distribution at the contact surface and find the best helical angle of the double-arc tooth Harmonic Drive tooth model. In a set of Harmonic Drive, the toothed parts are the circular spline and the flex spline. The circular spline will be hardened and harder than the flex spline after the heat treatment. Therefore, this paper mainly focuses on the discussion of the flex spline.
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LIN, CHIH-HENG, and 林志衡. "Coplanar Waveguide-fed Circularly Polarized Antennas with Wideband Harmonic Suppression." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u2gp8u.
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碩士逢甲大學
電機工程學系
106
This paper focuses on new type antennas of harmonic suppression with circular polarization. The π-shape resonator can be used to suppress the high-order frequency. They can be applied to wireless local area networks WLAN 5.8 GHz (5.725 GHz to 5.825 GHz) and DSRC 5.9 GHz (5.85 GHz to 5.925 GHz). A coplanar waveguide-fed circularly polarized antenna with harmonic suppression is initially proposed (proposed antenna 1). The antenna size is 30 mm× 30 mm× 0.762 mm. By adding two quadrant arc-shaped perturbed elements into the circular patch antenna, a circularly polarized (CP) band is excited from 5.85 GHz to 5.925 GHz. The π-shape resonator is loaded at the end of coplanar waveguide feed and coupled with the circularly polarized patch antenna. The measured 10-dB bandwidth and CP bandwidth were 660 MHz (5.67 GHz～6.33 GHz) and 75MHz (5.85 GHz～5.925 GHz), respectively. The measured maximum antenna gain and antenna efficiency were 5.5 dBic and 84.1%, respectively. The design of proposed antenna 2 is based on the architecture of proposed antenna 1. In order to increase the CP bandwidth without changing the structure of the resonator, a crescent slot is embedded into the ground plane. This design can increase the CP bandwidth to 5.72 GHz～5.88 GHz, which can cover the WLAN 5.8 GHz band (5.72 GHz～5.85 GHz). The measured 10-dB bandwidth was 850 MHz (5.7 GHz～6.55 GHz). The measured maximum antenna gain and antenna efficiency were 3.9 dBic and 81%, respectively.
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林辰彥. "Vibration induced by harmonic loadings applied at circular rigid plate on layered half-space medium." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/76236813452565858717.
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Tsai, Chi-Ying, and 蔡奇穎. "Analysis of Conjugate Range for Double- Circular-Arc and Common Tangent Profile of Harmonic Drive." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/858z3m.
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碩士國立臺北科技大學
製造科技研究所
105
Conjugate range of harmonic drive have a great influence on gear transmission performance, it depends on the tooth profile, number of teeth, structure of flexspline, and so on. Therefore, conjugate parameters have an influence on conjugate range will be discussed in this thesis. In this thesis, staring form rack tool for manufacture of flexspline, according to the standard of double-circular-arc and common tangent profile, solving the equation of tooth profile of flexspline conjugate to rack tool by tooth profile normal raw. Constructing a complete meshing model for harmonic drive. According to the B matrix method or the envelope principle, the circular spline tooth equation with the flexspline conjugate is solved. In order to avoid the error and interference caused by the harmonic drive meshing, this paper uses the exact solution for mathematical calculation. This paper uses MATLAB to write mathematical models. According to the user input engagement conditions, we can get the flexspline tooth profile and the circular spline tooth profile and conjugate range. To discuss the influence rule of tooth parameters and meshing parameters on the conjugate range. The best conjugation condition is adjusted to obtain the maximum conjugation performance.
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Liang, Tsair-Chun, and 梁財春. "Optical pattern recognition using a composite 2-D symmetrical edge detection filter and circular harmonic filter." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/41949326936088438729.
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SHIH, MING-CHOU, and 施名洲. "Scattering Problem of a Vertical Transverse Isotropic Circular Cylindrical Cavity Subjected to Time-Harmonic Elastic Wave." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8r96d5.
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Tien, Ling, and 田翎. "The Design of Near-Field Coupled Circular Sector Microstrip Antenna Pair with Harmonic-Rejection for Wireless Power Transmission." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/cjqar8.
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碩士國立臺北科技大學
電子工程系研究所
105
In this dissertation, a design of transmitting-receiving antenna pair in the near-field coupled for Wireless Power Transmission (WPT) is proposed. It can be applied in two different situations is near-field transmission and far-field transmission, respectively. In the near-field, by analyzing the field distribution and the reflector of the transmit-receive antenna pair within the reactive near-field region, the transmission coefficient of the proposed antenna pair can be optimized. On the other hand, the receiving antenna combined with the rectifier circuit can be seen as a rectenna at 2.4GHz when receiving antenna standalone. The proposed antenna pair utilized two different structure of circular sector microstrip Antenna. Through the relevance between the angle of circular sector and Bessel Function can achieve harmonic suppression effect. In order to improve the transmission efficiency, use the observation surface to observe the electromagnetic field distribution, and adjust the antenna structure parameters. Finally, the transmission efficiency of the antenna pair up to 92.3% at 2.45GHz. The proposed structure combine antenna with rectifier circuit, the receiving RF energy which in front of the antenna, through the rectifier circuit can convert to DC output. The maximum overall efficiency of the proposed antenna pair is more than 80% where the transmitted power reached 19 dBm. This architecture is ideal for wireless power transmission.
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Cheng, Yun-Hao, and 程雲豪. "Study on the Tooth Profile Design and Finite Element Analysis (FEA) of Harmonic Drives with Involute Profile and Double-Circular-Arc Profile." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/34774t.
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碩士國立中央大學
機械工程學系
105
The purpose of this study is to analyze the meshing characteristics of harmonic drives (HD) with involute profile and double-circular-arc profile. Firstly, the 2-D mathematical model of flexsplines (FS) with involute tooth profile and double-circular-arc profile were developed by using respective rack cutter based on the theory of gearing. Then the engaging circular spline (CS) with conjugate tooth profile of FS was derived based on the enveloping theory and kinematic model of HD. Additionally, a mesh generation program was developed to discretize the FS based on the 2-D mathematical model. Furthermore, 2-D FEA was conducted to explore the engagement movement of the FS, the torsional stiffness, transmission ratio, fillet stress and contact stress of the FS during meshing process and the engaged area of teeth of the HD under various conditions. In this study, an optimization method was adopted in the parametric design of 2-D tooth profile. The optimization aims to achieve the maximum torsional stiffness, and the constraints are that the stress is smaller than the fatigue limit of the FS material and no interference between the teeth of FS and CS is presented. An 2-D tooth profile optimization processing combining c++, finite element analysis and optimization algorithm was successfully performed. Moreover, a preliminary 3-D FEA was conducted to explore the torsional stiffness and the engaged area of teeth of the HD under two conditions, such as HD with lead crowning or HD without lead crowning by adding in axial parameters, including cup length, tooth width and so on. Finaly, The results from 2-D FEA and 3-D FEA were compared and discussed. The proposed methodology in this study paved the way for future investigations of 3-D FEA and 3-D optimization. keywords：harmonic drive, torsional stiffness, engaged area of teeth, involute tooth profile, double-circular-arc profile, finite element analysis, optimization