Дисертації з теми "Coupled excitation"
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1
Young, Anita. "Fluorescence studies in the inductively coupled plasma." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/1686.
Повний текст джерелаАнотація:
An Optima 3000 ICP-AES instrument was modified and the equipment necessary to carry out axial excitation atomic fluorescence was designed and constructed. Using this calibrated system, preliminary fluorescence experiments were not successful. As fluorescence is proportional to source intensity, it was considered that the excitation source, a hollow cathode lamp, may not have been sufficiently intense to produce fluorescence. A novel excitation source-driver system was designed and built in-house to operate HCLs, BDHCLs and LEDs with variable modulation frequencies and duty cycle capabilities. Studies investigating lamp response to changes in modulation frequency and duty cycle indicated that a lamp operated with a lower modulation frequency range (167 - 542 Hz) and higher duty cycles (30 - 50 %) should provide the preferred intense excitation conditions for the production of fluorescence in the ICP, When a Thermo Elemental PQ2 instrument was used, fluorescence was obtained immediately. Um'variate searches were used to optimise several plasma parameters, i.e. forward power; viewing height ALC; plasma, nebuliser and auxiliary gas flow rates. Once the optimum conditions had been determined, calibration curves were plotted for each of the elements studied (Ba, Li, Mg and Na). The calibration showed excellent linearity over five orders of magnitude (R? values ranged from 0.99995 to 1.0000) and the precision on each data point was better than 5 % RSD. Limits of detection were determined to be 27.6, 0.51, 0.43 and 0.20 ug 1* for Ba, L i , Mg and Na, respectively, which approached those reported in the literature for a commercial system. Vertical profiles of the plasma, using radial excitation, were obtained for Ba, Li , Mg and Na. Using the optimum conditions for Li and Na, vertical profiles of the plasma, using axial excitation with the more intense LEDs, were obtained. Both profiles showed that there was a relatively sharp optimum, with respect to fluorescence signal, as a function of viewing height ALC. The optimum viewing heights ALC obtained, for both radial and axial excitation fluorescence, were identical, suggesting that, irrespective of the excitation arrangement employed, only particular conditions produced in the plasma give the optimum conditions for fluorescence and that these are spatially dependent. Plasma diagnostics were performed in an attempt to explain why fluorescence was observed using the plasma produced by the Thermo Elemental but not by the Optima 3000 generator. At a viewing height of 50 mm ALC, Texc and Trot were 3080 and 2500 K for plasmas produced using the Thermo Elemental generator and 3600 and 2830 K for the Optima 3000 generator, respectively. Temperatures were calculated using the mean emission intensity at particular wavelengths. The intensities of the emitting species from the Thermo Elemental ICP were lower than those obtained from the Optima 3000 ICP for supposedly 'identical' conditions. If the number of excited species gives rise to lower emission intensities, then there must be more atoms in the lower/ground state from the plasma produced using the Thermo Elemental generator. This is of vital importance because for fluorescence to occur the fluorescence emission intensity will be dependent on the number available in the ground state for excitation {i.e. a relatively 'cool' plasma is required for fluorescence to occur). As very similar plasma operating conditions and the same concentration solutions were used in the fluorescence experiments performed using both the Optima 3000 and the Thermo Elemental ICPs, the differences observed in plasma performance may be attributed to efficiency of coupling of the generators used.
2
Caughlin, Brenda Lea. "Analyte excitation and ionization in the argon inductively coupled plasma." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27038.
Повний текст джерелаАнотація:
A new approach to evaluating departures from local thermal equilibrium (LTE) in the inductively coupled plasma (ICP) is described. Experimentally evaluated electron density (n[sub e]) is used as the basis for an LTE framework.
Spatially resolved, radial electron density profiles were measured under a variety of plasma operating conditions. The variation of n[sub e] with spatial position, aerosol flow rate, input power and presence of easily ionizable elements was determined. The measured n[sub e] was used to calculate an LTE temperature, T[sub e,LTE]. This temperature was higher than most spectroscopically measured temperatures in the plasma.
LTE ion-atom emission intensity ratios for Sr, Ca, Mg, Cd and Zn were calculated from n[sub e] and T[sub e,LTE] compared to experimental values. Ion-atom ratios were within an order of magnitude of LTE values and, in most cases, less than the LTE values. The infrathermal ion-atom ratios were interpreted as being due to an overpopulation of the atom levels relative to LTE populations.
Experimental degree of ionization was evaluated for a number of elements and compared to LTE values. Elements were underionized relative to LTE values. Degree of ionization and departure from LTE were correlated with ionization potential of the element. Elements with a high ionization potential had lower degrees of ionization and exhibited greater departures from LTE than elements of lower ionization potential.
The underionization and infrathermal ion-atom intensity ratios are attributed to overpopulation of atom levels. The experimental observations and results of other plasma diagnostic studies are discussed in terms of a partial LTE (p-LTE) model for the ICP. The ion ground state and upper energy levels of atoms are in Saha equilibrium. Lower atomic levels are over populated with respect to these levels. The overpopulation of the lower levels is a consequence of radiative depopulating processes, such as radiative decay and radiative recombination, not being balanced by their inverse absorption processes. For low lying atomic levels where radiative processes make significant contribution to the total depopulation rates this improper balance causes deviations from LTE populations. The atom ground state is the most overpopulated level and overpopulation decreases with increasing energy of the level until p-LTE is reached for the upper atomic levels.Science, Faculty of
Chemistry, Department of
Graduate
3
Kubota, Madoka. "Energy Harvesting Characteristics of Nonlinear Oscillators under Excitation." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199315.
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4
Lebrun, Romain. "Coupled vortex dynamics in spin-torque oscillators : from resonant excitation to mutual synchronization." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS233/document.
Повний текст джерелаАнотація:
La découverte de la magnétorésistance géante en 1988 est considérée comme la date de naissance d’un nouveau et dynamique champ de recherche appelé l’électronique de spin. La riche physique associée au transport de spin devrait révolutionner le futur de la nanoélectronique. Dans ce cadre les nano-oscillateurs à transfert de spin (STOs) se sont positionnés comme des candidats sérieux pour le développement d’une nouvelle génération de dispositifs rf basés sur l’électronique de spin.Au début de ma thèse, l’important bruit de phase des STOs restait une contrainte majeure limitant les perspectives technologiques à ce type d’oscillateurs. Dans cette thèse nous avons cherché à contrôler la dynamique des STOs et à réduire leur bruit phase en développant différentes stratégies : (i) l’optimisation des propriétés des matériaux magnétiques utilisés (ii) l’excitation de modes couplés dans des systèmes hybridés (iii) la stabilisation de la dynamique de la phase d’un STO avec un signal extérieur de référence (iv) la synchronisation mutuelle de différents oscillateurs pour améliorer la cohérence spectrale et la puissance des STOs. Nous focalisons en particulier sur le cas de STO à base de vortex magnétique qui présentent intrinsèquement des cohérences spectrales plus élevées que celles d’autres types d’oscillateurs.Dans une première partie, nous nous proposons d’identifier et d’étudier les différents mécanismes qui régissent et contrôle la dynamique d’un STO à base de vortex magnétique dans les régimes auto-oscillant et non-autonomes. Nous mettons tout d’abord en évidence que l’excitation de modes couplés permet de contrôler les propriétés rf d’un oscillateur unique en prenant l’exemple d’un STO à base de deux vortex magnétiques couplés. Par la suite, nous étudions la synchronisation « parfaite » de ces STOs à base de vortex avec un courant rf de référence. Nous corrélons l’observation d’une largeur de raie d’un hertz et d’un bruit de phase minimum de -90 dBc/Hz à 1kHz de la porteuse dans l’état synchronisé à une absence de glissement de phase, i.e. à l’absence de phénomène de désynchronisation. Le fort couple de Field-like planaire mesuré dans ces STOs représente un outil précieux pour contrôler le processus de synchronisation. Dans le cas des STOs à double vortex, un tel contrôle nous permet d’observer des phénomènes physiques exotiques allant de la synchronisation simultanée de plusieurs modes, à de l’auto-synchronisation en passant par des dynamiques de synchronisation incohérentes.Dans une seconde partie, nous proposons différents concepts innovants de dispositifs rf à base de vortex magnétique. Nous présentons tout d’abord les bases d’une boucle à retard de phase permettant d’asservir un STO. En prenant avantage du fort couple de Field Like, nous développons un nouveau schéma de détection rf, plus efficace que les actuelles diodes Schottky, basé sur un renversement d’aimantation en expulsant réversiblement le cœur de vortex à l’aide d’un courant rf. Finalement, nous démontrons qu’il est possible de synchroniser électriquement deux STOs connectés directement en parallèle ou en série, ou à l’aide d’une ligne à retard. Nous montrons ainsi qu’une forte amélioration de la cohérence spectrale (d’un facteur 2) et de la puissance (d’un facteur 4 pour un maximum de 1.6 μW) peut être obtenues dans l’état synchronisé. A l’aide de la ligne à retard, nous mettons par ailleurs en évidence le rôle crucial du déphasage entre les deux STOs sur les propriétés de l’état synchronisé. Ces résultats prometteurs ouvrent la voie vers la synchronisation de réseaux de STOs sans champ appliqué et sans ligne à retard entre les oscillateurs.Dix ans après leur découverte, les oscillateurs à transfert de spin n’ont toujours pas dévoilé tout leur potentiel et de nouvelles applications sont maintenant envisagées, allant de dispositif rf classiques à des circuits logiques et dispositifs bio-inspirés basés sur les STOsThe discovery of the giant magnetoresistance in 1988 is considered as the birth date of a new and dynamic research field called spintronics. The rich physics associated with spin transport has created a breakthrough for the future of nano-electronics. In the magnetism roadmap, spin-torque oscillators (STOs) are candidates for future generation of spintronic based rf-devices.At the beginning of this thesis, one major issue of spin-torque oscillators remained their poor spectral coherence. To overcome this issue, we have investigated different approaches: (i) the development of magnetic materials with a low damping and large spin-polarization, (ii) the study of collective mode dynamics in hybridized magnetic systems (iii) the stabilization of the STO dynamics with a reference external signal (iv) the synchronization of multiple STOs to enhance both their power and spectral coherence. We focus our work on vortex based STOs which present higher spectral coherences than other kinds of STOs.In a first part, we study the different mechanisms that can drive and stabilize the dynamics of a vortex based STO in the autonomous and non-autonomous regimes. We first highlight that the excitation of collective modes allows the harnessing the rf-properties of a single and isolated in a double vortex based STO. Then we report the ``perfect'' phase-locking of a STO with an external rf-current. To go beyond this analysis, we notice that a 1 Hz minimum linewidth and a flat phase noise level of -90 dBc/Hz at 1 kHz from the offset frequency in the locked state could be associated with the absence of phase slips, i.e desynchronization events. We demonstrate that the locking process is driven by a Field-like in-plane torque which gives the possibility to control with precision the STO locking process. In our double vortex based STO, we can even observe exotic behaviors such as multi-mode synchronization, self-resonance and eventually incoherent motion. Such a degree of control, unexpected for a nano-scale oscillator, is particularly promising for the development of STO based nanodevices.In a second part, we propose different concepts of spintronic rf-devices based on vortex STOs. We describe the basis of an on-chip STO based phase locked loop. By taking advantage of the large Field-like torque in our STOs, we develop a new radio-frequency detection scheme, more efficient than the state of the art Schottky diode, based on magnetization switching through the resonant and reversible expulsion of the vortex core. Finally, we show the first experimental observation of the electrical synchronization of two STOs connected directly in parallel or in series, or with an electrical delay line. In the synchronized state, we show a strong improvement of both the spectral coherence (by a factor 2) and the output power (by a factor 4, up to 1.6 μW). We also demonstrate, with an electrical delay line, the strong impact of the phase shift between the two STOs on the synchronized regime. These promising results open the way for the synchronization of STO arrays at zero field and without electrical delays.Ten years after their discovery, spin-torque oscillators have thus not yet revealed all their potential and promising applications could be soon targeted, in order to realize a spin logic circuit, bio-inspired spintronic devices and more classical rf-applications
5
Tzanidis, Ioannis. "Ultrawideband Low-Profile Arrays of Tightly Coupled Antenna Elements: Excitation, Termination and Feeding Methods." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316439948.
Повний текст джерела
6
Garrido, Mauricio. "Quantum Optics in Coupled Quantum Dots." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1273589966.
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7
Patil, Anjali Narendra. "Delamination Detection in Concrete Using Disposable Impactors for Excitation." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3885.
Повний текст джерелаАнотація:
Delaminations in concrete bridge decks result primarily from corrosion of the reinforcing bars (or rebar). This corrosion leads to volumetric expansion of the rebar. When the rebar expands, concrete cracks, and there is a localized separation of the concrete cover from the underlying concrete. Impact-echo testing is an effective technique to map delaminations on concrete bridge decks. However, mapping speed is limited by necessary retrieval of the impactor for traditional tests. To achieve higher scanning speeds, it is advantageous to use both a non-contact measurement (air-coupled impact-echo) and disposable-impactor excitation. Disposable impactors have the potential advantage of achieving greater deck scanning speeds because they do not need to be retrieved, and they can also be used with air-coupled measurement systems. This thesis reports impact excitation of concrete using disposable impactors such as water droplets and ice balls. The impact characteristics of these impactors are compared with those of steel balls and chain links. Comparing the acoustic recordings on intact and delaminated concrete surface shows that water droplets and ice balls are able to excite flexural resonant modes associated with delamination defects. The use of water droplets and ice balls for shallow delamination detection in concrete is thus demonstrated.
8
陳志遠 and Chee-yuen George Chan. "Investigation of matrix effects on excitation conditions of dry inductively coupled plasma using laser ablation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B42128687.
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9
Chan, Chee-yuen George. "Investigation of matrix effects on excitation conditions of dry inductively coupled plasma using laser ablation." Click to view the E-thesis via HKUTO, 2000. http://sunzi.lib.hku.hk/hkuto/record/B42128687.
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10
Smith, Thomas Riddell. "Excitation processes within an inductively coupled plasma as a function of pressure and related studies." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184582.
Повний текст джерелаАнотація:
Spectroscopic investigations have been carried out on an argon inductively coupled plasma operating at non-atmospheric pressure. The relationship between torch pressure and a number of plasma operating characteristics was explored for torch pressures between 100 and 3000 torr. The plasma operating characteristics examined include observed analyte emission intensities, electron densities, ion to atom ratios, and the deviation of plasma conditions from local thermodynamic equilibrium. The effect of pressure on the observed analyte emission intensities was found to include factors in addition to the change in density of species within the torch. Emission lines originating from ions and atoms with high ionization potentials (greater than 7 eV) increased in intensity with increasing torch pressure, in excess of that predicted by the increase in density of species present. Conversely, emission lines originating from atoms of low ionization potential decreased in intensity with increasing torch pressure despite the increase in density. The results of the spatial determination of electron densities and ion to atom ratios indicate that excitation conditions within the central channel of the plasma are shifted towards conditions of local thermodynamic equilibrium as the pressure within the torch is increased. In addition, it is possible to obtain improved limits of detection by optimizing the torch pressure for the analyte element of interest.
11
Reeves, Kevin. "Dynamic-systems analysis of self-excitation associated with a capacitor-coupled substation (CCS) - induction machine system." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/5116.
Повний текст джерелаАнотація:
Includes bibliographical references.The purpose of this thesis is therefore to establish the cause of SSR at the Meru-Petronet system, and other similar systems, and investigate various compensation techniques.
12
Hubert, Mickaël. "Relativistic coupled cluster theory for excited states at a general excitation rank : applications to diatomic molecules." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2046/.
Повний текст джерелаАнотація:
Cette thèse s'articule autour de développements méthodologiques sur l'évaluation théorique des énergies quantiques et relativistes d'état électroniquement excité d'atome ou de molécule. La méthode basée sur la fonction d'onde "Coupled Cluster" (CC) est à l'heure actuelle, une des méthodes les plus précise pour calculer ces états pour les systèmes à N-corps. L'implémentation présentée est basée sur un Hamiltonien relativiste à N-corps: Dirac-Coulomb à 4 composantes et une fonction d'onde "Coupled Cluster" au rang d'excitation arbitraire. Les états excités sont évalués via la théorie de la réponse linéaire, en diagonalisant la matrice Jacobienne Coupled Cluster. L'accent des travaux se porte sur l'évaluation de ses éléments en seconde quantification via un nouvel algorithme basé sur les commutateurs, et sur son adaptation au formalisme relativiste de Dirac à 4 composantes. Enfin, des applications du code à des molécules diatomiques non triviales seront présentéesThis thesis focuses on methodological developments of the theoretical evaluation of the quantum and relativistic energy of electronically excited states of an atom or a molecule. The wave-function method Coupled Cluster (CC) is currently one of the most accurate methods to calculate these states for many-body systems. The implementation presented is based on the many-body relativistic 4-component Dirac-Coulomb Hamiltonian and a Coupled Cluster wave function at arbitrary excitation rank. The excited states are evaluated using linear response theory by diagonalizing the Coupled Cluster Jacobian matrix. The work focuses on the evaluation of these second-quantized elements using a new commutator-based algorithm, and on its adaptation to a Dirac 4-component relativistic formalism. Finally, I present some applications of the code to challenging diatomic molecules
13
Soukup, Darin J. "A coupled local mode approach to laterally heterogeneous anisotropic media, volume scattering, and T-wave excitation /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6847.
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Cheung, Wai-kwong Andy, and 張偉光. "Investigation of probe insertion effects on plasma excitation conditions in direct sample insertion-inductively coupled plasmaatomic emission spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45014747.
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Cheung, Wai-kwong Andy. "Investigation of probe insertion effects on plasma excitation conditions in direct sample insertion-inductively coupled plasma atomic emission spectrometry /." View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31490955.
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16
Jagau, Thomas-Christian [Verfasser]. "Higher-order molecular properties and excitation energies in single-reference and multireference coupled-cluster theory / Thomas-Christian Jagau." Mainz : Universitätsbibliothek Mainz, 2013. http://d-nb.info/1035840286/34.
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Samanta, Pradipta Kumar [Verfasser], and Andreas [Akademischer Betreuer] Köhn. "Excitation energies and response properties of molecules using internally contracted multireference coupled cluster methods / Pradipta Kumar Samanta ; Betreuer: Andreas Köhn." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1153008548/34.
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18
Kottmann, Jakob Siegfried. "Coupled-Cluster in Real Space." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19357.
Повний текст джерелаАнотація:
In dieser Arbeit werden Algorithmen für die Berechnung elektronischer Korrelations- und
Anregungsenergien mittels der Coupled-Cluster Methode auf adaptiven Gittern entwickelt
und implementiert. Die jeweiligen Funktionen und Operatoren werden adaptiv durch
Multiskalenanalyse dargestellt, was eine Basissatz unabängige Beschreibung mit kontrollierter
numerischer Genauigkeit ermöglicht. Gleichungen für die Coupled-Cluster Methode
werden in einem verallgemeinerten Rahmen, unabhängig von virtuellen Orbitalen
und globalen Basissätzen, neu formuliert. Hierzu werden die amplitudengewichteten
Anregungen in virtuelle Orbitale ersetzt durch Anregungen in n-Elektronenfunktionen,
welche durch Gleichungen im n-Elektronen Ortsraum bestimmt sind. Die erhaltenen
Gleichungen können, analog zur Basissatz abh¨angigen Form, mit leicht angepasster Interpretation
diagrammatisch dargestellt werden. Aufgrund des singulären Coulomb Potentials
werden die Arbeitsgleichungen mit einem explizit korrelierten Ansatz regularisiert.
Coupled-Cluster singles mit genäherten doubles (CC2) und ähnliche Modelle werden,
für geschlossenschalige Systeme und in regularisierter Form, in die MADNESS Bibliothek
(eine allgemeine Bibliothek zur Darstellung von Funktionen und Operatoren mittels
Multiskalenanalyse) implementiert. Mit der vorgestellten Methode können elektronische
CC2 Paarkorrelationsenergien und Anregungsenergien mit bestimmter numerischer
Genauigkeit unabhängig von globalen Basissätzen berechnet werden, was anhand von
kleinen Molekülen verifiziert wirdIn this work algorithms for the computation of electronic correlation and excitation energies with the Coupled-Cluster method on adaptive grids are developed and implemented. The corresponding functions and operators are adaptively represented with multiresolution analysis allowing a basis-set independent description with controlled numerical accuracy. Equations for the coupled-cluster model are reformulated in a generalized framework independent of virtual orbitals and global basis-sets. For this, the amplitude weighted excitations into virtuals are replaced by excitations into n-electron functions which are determined by projected equations in the n-electron position space. The resulting equations can be represented diagrammatically analogous to basis-set dependent approaches with slightly adjusted rules of interpretation. Due to the singular Coulomb potential, the working equations are regularized with an explicitly correlated ansatz. Coupled-cluster singles with approximate doubles (CC2) and similar models are implemented for closed-shell systems and in regularized form into the MADNESS library (a general library for the representation of functions and operators with multiresolution analysis). With the presented approach electronic CC2 pair-correlation energies and excitation energies can be computed with definite numerical accuracy and without dependence on global basis sets, which is verified on small molecules.
19
Kurucu, Salur Riza. "A New Design Of Excitation Mechanism To Be Exploited By Modern Rf Excited Co2 Lasers." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605394/index.pdf.
Повний текст джерелаАнотація:
On this thesis work, design and construction of an up to date complete RF excitation system was intended. This excitation system is mainly based on highly efficient switching power generators and proper coupling of the power to the object plasma. This new excitation system design should answer the demands of today's progressed CO2 lasers on various power ranges. Though it could be used by a large variety of applications including RF plasma and RF heating, on the first occasion in order to define design considerations, this system is to be exploited by RF excited fast flow and RF excited slab CO2 laser constructions.
20
Frank, Marius Sebastian [Verfasser], Christof [Gutachter] Hättig, and Volker [Gutachter] Staemmler. "Implementation of coupled cluster excitation energies and gradients using pair natural orbitals / Marius Sebastian Frank ; Gutachter: Christof Hättig, Volker Staemmler ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1240479395/34.
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21
Boztosun, Ismail. "Coupled-channels calculations for the scattering of deformed light heavy-ions : a challenge to the standard approach." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325373.
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Huiza, Juan Félix Pari. "Estudo do acoplamento dos canais diretos de reação nos sistemas 16,17,18O + 64Zn." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-14102010-135321/.
Повний текст джерелаАнотація:
Funções de excitação para o espalhamento quase-elástico (elástico, inelásticos e transferências) foram medidas para os sistemas 16O +64 Zn, 17O +64 Zn e 18O +64 Zn, no ângulo traseiro de 161º, no referencial de laboratório, e em energias compreendidas entre 30:0 e 46:0 MeV , usando pequenos passos de 0:5 e 1:0 MeV , para energias abaixo e acima da barreira de Coulomb. Realizando uma derivada sobre dados experimentais, foram obtidas as distribuições de barreiras quase-elásticas para os três sistemas, as quais são equivalentes às distribuições de barreiras de fusão e revelam o mecanismo de reação dos sistemas. Para obter esses dados foi necessário uma boa resolução em carga, Z, do detector proporcional a gás, E-E, e também o uso de detectores barreira de superfície colocados em ângulos dianteiros, ±30º e -45º, utilizados para normalização de nossas medidas. Uma análise teórica dos dados foi realizada usando o modelo de canais de reação acoplados CRC através dos programas FRESCO [Thom 88] e CQUEL [Hagi 04] (uma nova versão do CCFULL [Hagi 99]). Em nossos cálculos, para evitar o uso de parâmetros livres, decidimos usar o potencial real de dupla convolução de São Paulo [Cham 02] que descreve físicamente a interação núcleo-núcleo, se baseia na não-localidade de Pauli e se caracteriza pela troca de nucleons. O potencial imaginário, responsável pela absorção do uxo de partículas que vai para fusão, foi restrita para ser de curto alcance e, desta maneira, não se afetar os processos quase-elásticos. Na análise teórica dos dados da função de excitação de transferência de um e dois nêutrons para os sistemas 17O +64 Zn e 18O +64 Zn, foi feito um ajuste para se obter informações espectroscópicas experimentais de vários estados do 65Zn e do 66Zn, as quais foram usados na análise da função de excitação e distribução de barreiras quase-elásticas para cada sistema. Os resultados obtidos nesses três sistemas são muito interessantes: o sistema 16O+64Zn mostra que os canais mais importantes que contribuem para um aumento da seção de choque de fusão são os estados 2+1 e 3-1 do alvo [Huiz 07] (CQUEL), e o estado 3-1 do projétil (FRESCO). No sistema 17O +64 Zn resultou que os estados excitados do quadrupolo e octupolo do alvo, 2+ 1 e 3-1 , são acoplados fortemente ao canal do elástico mas foi necessário acoplar o canal de transferência de um nêutron para descrever os nossos dados. Da mesma maneira, o sistema 18O+64 Zn ratificou que esses dois estados do alvo se acoplam fortemente ao canal de transferência de dois nêutrons, porém foi necessário incluir na matriz de acoplamento o canal de transferência de um nêutron utilizando os resultados obtidos para o sistema 17O +64 Zn, como uma aproximação. Verificamos que todos esses canais no sistema 18O +64 Zn descrevem os dados e tem forte influência sobre a forma da distribuição de barreira.Excitation functions for quasi-elastic scattering (elastic, inelastic and transfer) were measured for the 16O +64 Zn, 17O +64 Zn and 18O +64 Zn systems, at backward angles of 161º, in the laboratory reference system, and in the energy range between 30:0 and 46:0 MeV using steps of 0:5 and 1:0 MeV , for energies below and above the Coulomb barrier. Performing a derivative on experimental data we obtained the quasi-elastic barrier distributions for the three systems, which are equivalent to the fusion barrier distributions, and make evident the reaction mechanisms of the system. To obtain these data a good charge resolution \"Z\" of a gas proportional counter, E -E, was necessary and also the use of surface barrier detectors placed at forward angles, ±30º and -45167 for normalization. A theoretical analysis of the data was performed using the coupled reaction channel model CRC through the use of FRESCO [Thom 88] and CQUEL [Hagi 04] (a new version of CCFULL [Hagi 99]). To avoid the use of free parameters, in our calculations, we decided to use the real potential of the double-folding São Paulo Potencial [Cham 02], which describes physically the nucleus-nucleus interaction. It is based on Pauli non-locality and is characterized by the exchange of nucleons. The imaginary potential, responsible for the absorption of particles in a fusion process, was restricted to a very short range, and thus, it does not affect the quasi-elastic processes. In the theoretical analysis of the transfer excitation functions of one and two neutrons for the 17O+64Zn and 18O+64Zn systems, we obtained the spectroscopic information for some experimental states in 65Zn and 66Zn, which were used in the analysis of the excitation function and quasi-elastic barrier distributions for each system. The results obtained in these three systems are very interesting: the 16O +64 Zn system shows that the most important channels contributing to enhancement fusion cross section are the states 2+1 and 3-1 of the target [Huiz 07] (CQUEL), and the state 3-1 of the projectile (FRESCO). The 17O+64Zn system shows that the quadrupole and octupole excited states of the target, 2+ 1 and 3-1 , are strongly coupled to the elastic channel but it was necessary to couple the one neutron transfer channel in order to describe our data. Similarly, the 18O +64 Zn system confirmed that those two states of the target are strongly coupled to the two neutron transfer channel, but it was necessary to include in the coupling matrix the one neutron transfer channel. We verify that all these channels in the 18O +64 Zn describe the data and they in uence strongly the shape of the barrier distributions.
23
Simões, Rone Flávio. "Medidas das distribuições das barreiras de fusão para os sistemas 16,18O + 58,60Ni." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-18022014-153458/.
Повний текст джерелаАнотація:
Funções de excitação para o espalhamento quase-elástico foram medidas com alta precisão e em passos de energia de 500 keV para os sistemas 16,18O + 56,60Ni. Dessas funções de excitação foram extraídas as distribuições de barreiras de fusão. Cálculos de canais acolplados foram realizados com o objetivo de evidenciar os canais responsáveis pelas estruturas observadas nas distribuições. Foram usados dois códigos computacionais, o CCFULL e o FRESCO, e os resultados foram similares. Comparamos Dfus com Dqe fornecidas pelo programa FRESCO para todos os sistemas e verificamos que são praticamente idênticas, confirmando que a aproximação Dfus = Dqe deve ser válida para esta região de massa. O que podemos concluir com o CCFULL é que o stripping de alfa para o sistema 16O + 58Ni é o canal de transferência mais importante em energias acima da barreira. Embora o cálculo com o FRESCO tenha mostrado que a importância desse canal é pequena. Para o sistema 16O + 60Ni, o canal de acoplamento mais forte é o pickup de alfa. Para os dois outros sistemas, 18O + 58,60Ni, foi verificado que o canal de transferência stripping de um nêutron tem forte influência sobre a forma das distribuições da barreira. Além dos canais de transferência, em todos os sistemas verificamos que a excitação do alvo é um canal de reação importante nos acoplamentos que originam as distribuições de barreiras obtidas experimentalmente.Excitation functions for quasi-elastic scattering were measured with high precision with energy steps of 500 keV for the 16,18O + 56,60Ni systems. Fusion barrier distributions were extracted from the excitation functions. Coupled channel calculations were used in order to determine which channels are responsible for the structures observed in the experimental distributions. Two computation codes were used: CCFULL and FRESCO. Their results are similar. We compared Dfus with Dqe obtained with FRESCO and we have concluded that they are practically identical for all systems. This is a confirmation that the approximation Dfus = Dqe is reasonable in this mass region. The first conclusion with CCFULL code is that alpha stripping for the 16O + 58Ni system is the channel transfer most important at above barrier energies. However, the calculation with FRESCO showed that it has only minor importance. For the 16O + 60Ni system, the more expressive transfer channel is alpha pick-up. In the two other systems, 18O + 58,60Ni, we observed that one-neutron stripping has Strong influence on the barrier distributions. Beside the transfer channels, the target inelastic excitation is a very important reaction channel in all systems.
24
Janot, Alexander. "Quantum Condensates and Topological Bosons in Coupled Light-Matter Excitations." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-199239.
Повний текст джерелаАнотація:
Motivated by the sustained interest in Bose Einstein condensates and the recent progress in the understanding of topological phases in condensed matter systems, we study quantum condensates and possible topological phases of bosons in coupled light-matter excitations, so-called polaritons. These bosonic quasi-particles emerge if electronic excitations (excitons) couple strongly to photons.
In the first part of this thesis a polariton Bose Einstein condensate in the presence of disorder is investigated. In contrast to the constituents of a conventional condensate, such as cold atoms, polaritons have a finite life time. Then, the losses have to be compensated by continued pumping, and a non-thermal steady state can build up. We discuss how static disorder affects this non-equilibrium condensate, and analyze the stability of the superfluid state against disorder. We find that disorder destroys the quasi-long range order of the condensate wave function, and that the polariton condensate is not a superfluid in the thermodynamic limit, even for weak disorder, although superfluid behavior would persist in small systems. Furthermore, we analyze the far field emission pattern of a polariton condensate in a disorder environment in order to compare directly with experiments.
In the second part of this thesis features of polaritons in a two-dimensional quantum spin Hall cavity with time reversal symmetry are discussed. We propose a topological invariant which has a nontrivial value if the quantum spin Hall insulator is topologically nontrivial. Furthermore, we analyze emerging polaritonic edge states, discuss their relation to the underlying electronic structure, and develop an effective edge state model for polaritons.
25
Noga, Jozef, Stanislav Kedžuch, Ján Šimunek, and Seiichiro Ten-no. "Explicitly correlated coupled cluster F12 theory with single and double excitations." American Institite of Physics, 2008. http://hdl.handle.net/2237/12013.
Повний текст джерела
26
Kiendl, Thomas [Verfasser]. "Low-energy excitations in strongly coupled superconductor-magnet hybrids / Thomas Kiendl." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1176638769/34.
Повний текст джерела
27
Ohlsson, Sax Olof. "Spins and Giants : Fundamental Excitations in Weakly and Strongly Coupled ABJM Theory." Doctoral thesis, Uppsala universitet, Teoretisk fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151609.
Повний текст джерелаАнотація:
The discovery of integrability on both sides of the duality between planar N=4 super Yang-Mills theory and free type IIB string theory in AdS5 × S5 has lead to great progress in our understanding of the AdS/CFT correspondence. Similar integrable structures also appear in the more recent three-dimensional superconformal N=6 Chern-Simons-matter theory constructed by Aharony, Bergman, Jafferis and Maldacena (ABJM), as well as in its gravity dual, type IIA string theory on AdS4 × CP3. However, new interesting complications arise in the AdS4/CFT3 duality. In the conjectured all-loop Bethe equations by Gromov and Vieira the dispersion relation of the magnons has a non-trivial coupling dependence which is parametrized by a function that is only known to the leading order at weak and strong coupling. In the first part of this thesis I discuss our calculations of the next-to-leading correction to this function at weak coupling. We compute this function from four-loop Feynman diagrams in the SU(2) × SU(2) sector of the ABJM model. As a consistency check we have performed the calculation both in a component formalism and using superspace techniques. At strong coupling the fundamental excitations of the integrable model are the giant magnons. The topic of the second part of this thesis is the spectrum of these giant magnons in CP3. Furthermore, I discuss our analyses of the finite-size corrections beyond the asymptotic Bethe ansatz. At weak coupling we have computed the leading four-loop wrapping diagrams in the ABJM model. At the strong coupling side of the duality I discuss our results for the exponentially suppressed finite-size corrections to the energy of giant magnons.
28
Rust, Mike. "The Approximate Inclusion of Triple Excitations in EOM-type Quantum Chemical Methods." Scholarship @ Claremont, 2001. https://scholarship.claremont.edu/hmc_theses/135.
Повний текст джерелаАнотація:
In non-relativistic quantum mechanics, stationary states of molecules and atoms are described by eigenvectors of the Hamiltonian operator. For one-electron systems, such as the hydrogen atom, the solution of the eigenvalue problem (Schro ̈dinger’s equation) is straightforward, and the results show excellent agreement with experiment. Despite this success, the multi electron problem corresponding to virtually every system of interest in chemistry has resisted attempts at exact solution. Perhaps the most popular method for obtaining approximate, yet very accurate results for the ground states of molecules is the coupled cluster approximation. Coupled cluster methods move beyond the simple, average field Hartree-Fock approximation by including the effects of excited configurations generated in a size consistent manner. In this paper, the coupled cluster approximation is developed from first principles. Diagrammatic methods are introduced which permit the rapid calculation of matrix elements appearing in the coupled cluster equations, along with a systematic approach for unambiguously determining all necessary diagrams. A simple error bound is obtained for the ground state energy by considering the coupled cluster equations as entries in the first column of a matrix whose eigenvalues are the exact eigenvalues of the Hamiltonian. In addition, a strategy is considered for treating the error in the ground state energy perturbatively.
29
Comar, William D. Ph D. "ESTABLISHING AND MANIPULATING THE DIMERIC INTERFACE OF VISUAL/NON-VISUAL OPSINS." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152882487417841.
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30
Luthra, Antriksh. "Mid-IR Plasmonics, Cavity Coupled Excitations, and IR Spectra of Individual Airborne Particulate Matter." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu148362252748271.
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31
Fernique, François. "Collective plasmonic excitations in two- dimensional metamaterials based on near-field coupled metallic nanoparticles." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE012/document.
Повний текст джерелаАнотація:
L’étude des propriétés plasmoniques est un champ de recherche actuellement très actif. En particulier, la possibilité de manipuler la lumière à des échelles sub-longueur d’ondes rend ce domaine très attractif. Récemment, plusieurs études ont montré que les plasmons collectifs dans des méta-matériaux bi-dimensionnels constitués de nanoparticules métalliques se comportaient de manière similaire aux électrons dans les cristaux et partageaient certaines de leurs propriétés. Dans ce manuscrit, nous présentons une théorie unifiée permettant de décrire les propriétés de tels modes plasmoniques dans des réseaux ordonnés de géométrie arbitraires constitués de nanoparticules métalliques couplées en champ proche. En particulier, nous évaluons les taux de décroissance de ces modes ainsi que leurs décalages en fréquence afin de prédire leur observabilité expérimentaleThe study of plasmonic properties is one of the fields of research currently very active. In particular, the ability to manipulate light at subwavelength scales makes this subject very appealing. Recently, several studies have shown that collective plasmons in two-dimensional meta-materials based on metallic nanoparticles behave similarly to electrons in crystals and share some of their properties. In this manuscript, we present a unified theory for describing the properties of such modes in regular arrays of arbitrary geometries constituted by near-field coupled spherical nanoparticles. In particular, we have evaluated the linewidths of these modes as well as their frequency shifts in order to discussed their experimental observabilities
32
Davison, Richard A. "Excitations in holographic quantum liquids." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:3b1db914-709e-41ec-ba7c-c968cb87b752.
Повний текст джерелаАнотація:
In this thesis we review the gauge/gravity duality and how it can be used to compute the thermodynamic properties and low-energy excitations of holographic quantum liquids - strongly-interacting field theories with a non-zero density of matter. We then study in detail the charge density excitations of two such liquids, the D3/D7 theory and the RN-AdS₄ theory, by computing the poles of their charge density Green's functions, and their charge density spectral functions. Although it is not a Landau Fermi liquid, the charge density excitations of the D3/D7 theory display many of the same properties as one, including a collisionless/hydrodynamic crossover as the temperature is increased. In contrast to this, the charge density (and energy density) excitations of the RN-AdS₄ theory do not share these properties but behave in a way that cannot be explained by Landau's theory of interacting fermionic quasiparticles. This is consistent with other results which indicate that this is not a Landau Fermi liquid.
33
Huang, Ming-Hui. "Dynamic characteristics of slender suspension footbridges." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16450/1/Ming-Hui_Huang_Thesis.pdf.
Повний текст джерелаАнотація:
Due to the emergence of new materials and advanced engineering technology, slender footbridges are increasingly becoming popular to satisfy the modern transportation needs and the aesthetical requirements of society. These structures however are always "lively" with low stiffness, low mass, low damping and low natural frequencies. As a consequence, they are prone to vibration induced by human activities and can suffer severe vibration serviceability problems, particularly in the lateral direction. This phenomenon has been evidenced by the excessive lateral vibration of many footbridges worldwide such as the Millennium Bridge in London and the T-Bridge in Japan. Unfortunately, present bridge design codes worldwide do not provide sufficient guidelines and information to address such vibrations problems and to ensure safety and serviceability due to the lack of knowledge on the dynamic performance of such slender vibration sensitive bridge structures.
A conceptual study has been carried out to comprehensively investigate the dynamic characteristics of slender suspension footbridges under human-induced dynamic loads and a footbridge model in full size with pre-tensioned reverse profiled cables in the vertical and horizontal planes has been proposed for this purpose. A similar physical suspension bridge model was designed and constructed in the laboratory, and experimental testings have been carried out to calibrate the computer simulations. The synchronous excitation induced by walking has been modelled as crowd walking dynamic loads which consist of dynamic vertical force, dynamic lateral force and static vertical force. The dynamic behaviour under synchronous excitation is simulated by resonant vibration at the pacing rate which coincides with a natural frequency of the footbridge structure. Two structural analysis software packages, Microstran and SAP2000 have been employed in the extensive numerical analysis.
Research results show that the structural stiffness and vibration properties of suspension footbridges with pre-tensioned reverse profiled cables can be adjusted by choosing different structural parameters such as cable sag, cable section and pretensions in the reverse profiled cables. Slender suspension footbridges always have four main kinds of vibration modes: lateral, torsional, vertical and longitudinal modes. The lateral and torsional modes are often combined together and become two kinds of coupled modes: coupled lateral-torsional modes and coupled torsionallateral modes. Such kind of slender footbridges also have different dynamic performance in the lateral and vertical directions, and damping has only a small effect on the lateral vibration but significant effect on the vertical one.
The fundamental coupled lateral-torsional mode and vertical mode are easily excited when crowd walking dynamic loads are distributed on full bridge deck. When the crowd walking dynamic loads are distributed eccentrically on half width of the deck, the fundamental coupled torsional-lateral mode can be excited and large lateral deflection can be induced. Higher order vertical modes and coupled lateral-torsional modes can also be excited by groups of walking pedestrians under certain conditions.
It is found that the coupling coefficient introduced in this thesis to describe the coupling of a coupled mode, is an important factor which has significant effect on the lateral dynamic performance of slender suspension footbridges. The coupling coefficient, however, is influenced by many structural parameters such as cable configuration, cable section, cable sag, bridge span and pre-tensions, etc. In general, a large dynamic amplification factor is expected when the fundamental mode of a footbridge structure is the coupled lateral-torsional mode with a small coupling coefficient.
The research findings of this thesis are useful in understanding the complex dynamic behaviour of slender and vibration sensitive suspension footbridges under humaninduced dynamic loads. They are also helpful in developing design guidance and techniques to improve the dynamic performance of such slender vibration sensitive footbridges and similar structures and hence to ensure their safety and serviceability.
34
Huang, Ming-Hui. "Dynamic characteristics of slender suspension footbridges." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16450/.
Повний текст джерелаАнотація:
Due to the emergence of new materials and advanced engineering technology, slender footbridges are increasingly becoming popular to satisfy the modern transportation needs and the aesthetical requirements of society. These structures however are always "lively" with low stiffness, low mass, low damping and low natural frequencies. As a consequence, they are prone to vibration induced by human activities and can suffer severe vibration serviceability problems, particularly in the lateral direction. This phenomenon has been evidenced by the excessive lateral vibration of many footbridges worldwide such as the Millennium Bridge in London and the T-Bridge in Japan. Unfortunately, present bridge design codes worldwide do not provide sufficient guidelines and information to address such vibrations problems and to ensure safety and serviceability due to the lack of knowledge on the dynamic performance of such slender vibration sensitive bridge structures. A conceptual study has been carried out to comprehensively investigate the dynamic characteristics of slender suspension footbridges under human-induced dynamic loads and a footbridge model in full size with pre-tensioned reverse profiled cables in the vertical and horizontal planes has been proposed for this purpose. A similar physical suspension bridge model was designed and constructed in the laboratory, and experimental testings have been carried out to calibrate the computer simulations. The synchronous excitation induced by walking has been modelled as crowd walking dynamic loads which consist of dynamic vertical force, dynamic lateral force and static vertical force. The dynamic behaviour under synchronous excitation is simulated by resonant vibration at the pacing rate which coincides with a natural frequency of the footbridge structure. Two structural analysis software packages, Microstran and SAP2000 have been employed in the extensive numerical analysis. Research results show that the structural stiffness and vibration properties of suspension footbridges with pre-tensioned reverse profiled cables can be adjusted by choosing different structural parameters such as cable sag, cable section and pretensions in the reverse profiled cables. Slender suspension footbridges always have four main kinds of vibration modes: lateral, torsional, vertical and longitudinal modes. The lateral and torsional modes are often combined together and become two kinds of coupled modes: coupled lateral-torsional modes and coupled torsionallateral modes. Such kind of slender footbridges also have different dynamic performance in the lateral and vertical directions, and damping has only a small effect on the lateral vibration but significant effect on the vertical one. The fundamental coupled lateral-torsional mode and vertical mode are easily excited when crowd walking dynamic loads are distributed on full bridge deck. When the crowd walking dynamic loads are distributed eccentrically on half width of the deck, the fundamental coupled torsional-lateral mode can be excited and large lateral deflection can be induced. Higher order vertical modes and coupled lateral-torsional modes can also be excited by groups of walking pedestrians under certain conditions. It is found that the coupling coefficient introduced in this thesis to describe the coupling of a coupled mode, is an important factor which has significant effect on the lateral dynamic performance of slender suspension footbridges. The coupling coefficient, however, is influenced by many structural parameters such as cable configuration, cable section, cable sag, bridge span and pre-tensions, etc. In general, a large dynamic amplification factor is expected when the fundamental mode of a footbridge structure is the coupled lateral-torsional mode with a small coupling coefficient. The research findings of this thesis are useful in understanding the complex dynamic behaviour of slender and vibration sensitive suspension footbridges under humaninduced dynamic loads. They are also helpful in developing design guidance and techniques to improve the dynamic performance of such slender vibration sensitive footbridges and similar structures and hence to ensure their safety and serviceability.
35
Merdan, Mohammad Ghanim Merdan. "Study of the excited states of the quantum antiferromagnets." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/study-of-the-excited-states-of-the-quantum-antiferromagnets(dfd01ec6-806c-464a-9b68-910217679c3c).html.
Повний текст джерелаАнотація:
We investigate the quantum dynamics of the spins on different Heisenberg antiferromagnetic spin lattice systems. Firstly, we applied the coupled-cluster method to the spin-1/2 antiferromagnetic XXZ model on a square lattice by employing an approximation which contains two-body long-range correlations and high-order four-body local correlations. Improvement is found for the ground-state energy, sublattice magnetization, and the critical anisotropy when comparing with the approximation including the two-body correlations alone. We also obtain the full excitation spectrum which is in good agreement with the quantum Monte Carlo results and the high-order spin-wave theory. Secondly, we study the longitudinal excitations of quantum antiferromagnets on a triangular lattice by a recently proposed microscopic many-body approach based on magnon-density waves. We calculate the full longitudinal excitation spectra of the antiferromagnetic Heisenberg model for a general spin quantum number in the isotropic limit. Similar to the square lattice model, we find that, at the center of the first hexagonal Brillouin zone Γ(q=0) and at the magnetic ordering wavevectors ±[Q= (4π/3,0)], the excitation spectra become gapless in the thermodynamic limit, due to the slow, logarithmic divergence of the structure factor. However, these longitudinal modes on two-dimensional models may be considered as quasi-gapped, as any finite-size effect or small anisotropy will induce a large energy gap, when compared with the counterpart of the transverse spin-wave excitations. We have also investigated the excited states of the quasi-one-dimensional quantum antiferromagnets on hexagonal lattices, including the longitudinal modes based on the magnon-density waves. A model Hamiltonian with a uniaxial single-ion anisotropy is first studied by a spin-wave theory based on the one-boson method; the ground state thus obtained is employed for the study of the longitudinal modes. The full energy spectra of both the transverse modes (i.e., magnons) and the longitudinal modes are obtained as functions of the nearest-neighbor coupling and the anisotropy constants. We have found two longitudinal modes due to the non-collinear nature of the triangular antiferromagnetic order, similar to that of the phenomenological field theory approach by Affleck. The excitation energy gaps due to the anisotropy and the energy gaps of the longitudinal modes without anisotropy are then investigated. We then compares our results for the longitudinal energy gaps at the magnetic wavevectors with the experimental results for several antiferromagnetic compounds with both integer and non-integer spin quantum numbers, and we find good agreements after the higher-order contributions are included in our calculations.
36
Ozdemir, Gokhan. "Response Of Isolated Structures Under Bi-directional Excitations Of Near-field Ground Motions." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612039/index.pdf.
Повний текст джерелаАнотація:
Simplified methods of analysis described in codes and specifications for
seismically isolated structures are always used either directly in special cases or for
checking the results of nonlinear response history analysis (RHA). Important
predictions for seismically isolated structures by simplified methods are the
maximum displacements and base shears of the isolation system. In this study, the
maximum isolator displacements and base shears determined by nonlinear RHA are
compared with those determined by the equivalent lateral force (ELF) procedure in
order to assess the accuracy of the simplified method in the case of bi-directional
excitations with near-field characteristics. However, although there are currently
many methods for ground motion selection and scaling, little guidance is available
to classify which method is more appropriate than the others in any applications.
Features of this study are that the ground motions used in analysis are selected and
scaled using contemporary concepts and that the ground excitation is considered biv
directional. The variations in response of isolated structures due to application of
ground motions uni-directionally and bi-directionally are also studied by employing
a scaling procedure that is appropriate for the bi-directional analysis. The proposed
new scaling methodology is an amplitude scaling method that is capable of
preserving the horizontal orthogonal components and it is developed especially for
dynamic analysis of isolated structures. Analyses are conducted for two different
symmetric reinforced concrete isolated structure for two different soil conditions in
structural analysis program SAP2000. Effect of asymmetry in superstructure on
isolator displacement is also investigated with further analyses considering 5% mass
eccentricity at each floor level. Furthermore, once the significance of the orthogonal
horizontal component on the response of isolation system is shown, the biaxial
interaction of hysteretic behavior of lead rubber bearings is implemented in
OpenSees by developing a subroutine which was not readily available.
37
Rocha, Carlos Antonio da. "Medidas de seção de choque de fusão para os sistemas ANTPOT. 12 C + ANTPOT. 63, 65 CU." Universidade de São Paulo, 1987. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-01042014-093351/.
Повний текст джерелаАнотація:
No presente trabalho é apresentado um conjunto de medidas de seção de choque do processo de fusão nuclear nos sistemas ANTPOT. 12 C + ANTPOT. 63, 65 CU, em um intervalo de energia correspondente à 0.91.8 vezes a barreira coulombiana. O método experimental utilizado foi a detecção dos resíduos de evaporação através da técnica de tempo de vôo, acoplado à um defletor eletrostático para separar as partículas provenientes do espalhamento elástico dos produtos de fusão. As vantagens e limitações do método são discutidas em detalhes. As funções de excitação de fusão dos sistemas citados foram analisadas via modelo de penetração de barreira unidimensional , utilizando vários potenciais nucleares. Dessa análise comprovou-se que a secção de choque de fusão é subestimada em energias em torno e abaixo da barreira coulombiana. Nesse sentido foi feito um cálculo, utilizando o código computacional CCFUS, que simula o acoplamento de canais, com a finalidade de descobrir quais canais contribuem para o processo de fusão nuclear em baixas energias. As seções de choque de fusão obtidas foram comparadas com outros sistemas - ANTPOT. 12 C + ANTPOT. 63, 65 CU.- que utilizam os mesmos núcleos-alvo. A comparação revelou que os sistemas ANTPOT. 12 C + ANTPOT. 63, 65 CU possuem o maior aumento de seção de choque de fusão subcoulombiana e esse fato pode estar relacionado à deformação estática do projétil. A comparação das distribuições da velocidade dos resíduos de evaporação para os dois de sistemas revelou um canal intenso para o sistema ANTPOT. 12 C + ANTPOT. 63 CU que não está presente para o outro sistema.In this work we present cross-section measurements for nuclear fusion in the 12C+ 63,65 Cu system, at 12C energy range from 0.9 to 1.8 times the Coulomb barrier. In order to detect and to obtain the mass identification of the evaporation residues following the fusion process, the time of flight method was adopted in conjunction with an eletrostatic deflector capable of separating the evaporation residues from the beam particles. The limitation and advantadges of this method of measurement are discussed. The excitation functions for the above systems were analysed using the unidimensional barrier penetration model with different nuclear potentials. Theoretical fusion cross-section values obtained from this analysis were systematically smaller than our measured values, in the energy region below the Coulomb barrier. In order to discover which channel enhances the fusion cross-section in this region, a coupled channel calculation was performed, with the aid of CCFUS code. The experimental data for the above reactions were compared with the systems 12C+ 63,65 Cu, measured by our group. In this comparison, It was noted that the systems 12C+ 63,65 Cu have greater fusion cross section below the Coulomb barrier. This fact can be related to the static deformation of 12C. The comparison of velocity spectra of the evaporated residues for the two systems shows that 12C+63Cu has a strong reaction channel that was not present in the 12C+ 65Cu system.
38
Bouhafs, Nezha. "Excitation des hydrures d’azote par l’hydrogène atomique et moléculaire." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMLH15/document.
Повний текст джерелаАнотація:
L'observation et l'étude des milieux moléculaires tel que le milieu interstellaire requièrent une connaissance détaillée des vitesses des processus de peuplement radiatifs et collisionnels afin d'accéder aux caractéristiques physiques (températures, densités, abondances des molécules, ...) de ces milieux. Les hydrures d'azote sont très présents dans les milieux interstellaires où ils s'avèrent être des intermédiaires de réaction important dans la chimie de l'azote. L'interprétation des observations des hydrures d'azote réalisées grâce au satellite HERSCHEL et l'interféromètre millimétrique ALMA, nécessite de connaître avec suffisamment de précision les taux de collision de ces molécules. Nous nous sommes donc intéressés dans cette thèse à la détermination des taux de collisions inélastiques des hydrures NH, NH2 et NH3 avec Ne, H2 et H, respectivement. A partir de surfaces d’énergie potentielle, les sections efficaces ont été obtenues pour les trois systèmes par la méthode exacte des équations couplées en utilisant les codes de dynamique moléculaire MOLSCAT et HIBRIDON. Les taux de collision sont ensuite obtenus pour des températures allant de 5 à 200 K. Enfin, les nouveaux taux de collisions de NH2 avec H2 ont été utilisés dans un code de transfert radiatif afin de reproduire les observations de NH2 en direction d'un nuage de formation d’étoile massive W31C. Nous montrons que les nouveau taux de collisions calculés apportent des contraintes sur les conditions physiques du nuage moléculaireObservation and study of interstellar molecular clouds require the knowledge of molecular data to derive the physical conditions (temperature, gas density, molecular abundance) of these media. Nitrogen hydrides are highly abundant species in the interstellar medium and they are found to be important reaction intermediates in the nitrogen chemistry. The interpretation of nitrogen hydrides observations from the HERSCHEL spatial observatory and the ALMA interferometer, requires accurate collisional rate coefficients of these molecules. The present thesis focuses on the determination of new rate coefficients for NH, NH2 and NH3 molecules in collision with Ne, H2 et H, respectively. Inelastic cross sections for the rotational excitation of all the studied systems have been computed with a close coupling method using the molecular dynamic codes MOLSCAT and HIBRIDON. The cross sections are then used to calculate the collisional rate coefficients for temperatures ranging from 5 to 200 K. The new rate coefficients were included in radiative transfer calculations in order to model the observed transitions of NH2 towards high-mass star-forming region W31C. We show that using the previously published rate coefficients instead of these new ones have a significant impact on the modeling, leading to important differences on the density, abundance and on the OPR of NH2. The new data will allow to put interesting constraints on the physical condition of the molecular cloud
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Trippel, Richard [Verfasser], Robert [Akademischer Betreuer] Roth, and Achim [Akademischer Betreuer] Schwenk. "Collective Excitations with Chiral NN+3N Interactions from Coupled-Cluster and In-Medium SRG / Richard Trippel ; Robert Roth, Achim Schwenk." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1122286414/34.
Повний текст джерела
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Janot, Alexander [Verfasser], Bernd [Akademischer Betreuer] Rosenow, Bernd [Gutachter] Rosenow, and Ehud [Gutachter] Altman. "Quantum Condensates and Topological Bosons in Coupled Light-Matter Excitations / Alexander Janot ; Gutachter: Bernd Rosenow, Ehud Altman ; Betreuer: Bernd Rosenow." Leipzig : Universitätsbibliothek Leipzig, 2016. http://d-nb.info/1240398077/34.
Повний текст джерела
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Bricout, Marion. "Comportement du dioxyde d’uranium sous irradiation : effet couplé de l’endommagement nucléaire et des excitations électroniques." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP064.
Повний текст джерелаАнотація:
En réacteur, le combustible nucléaire est soumis à l’irradiation simultanée des neutrons, des particules alpha ou bêta et des fragments de fission, ce qui cause de nombreuses modifications physico-chimiques. A l’échelle atomique, les particules de haute énergie provoquent des ionisations et des excitations électroniques tandis que celles de plus basse énergie engendrent des cascades de déplacements atomiques. A l’échelle nanométrique, ces dommages induisent une évolution de la microstructure avec la création de cavités, de boucles et de lignes de dislocations, et, à l’échelle macroscopique, des phénomènes de gonflement et de restructuration qui peuvent affecter la stabilité du combustible. Bien que l’influence séparée des deux pertes d’énergie soit bien documentée, leur effet couplé n’a jamais été étudié de façon systématique dans le dioxyde d’uranium.L’objectif de cette thèse est donc d’étudier le couplage entre les pertes d’énergie électronique et nucléaire.Des irradiations aux ions, notamment en double faisceau simultanés, ont été menées sur les plateformes JANNuS Saclay et Orsay. Un couplage entre différentes techniques de caractérisation (MET, DRX et spectroscopie Raman) a été réalisé afin d’obtenir des informations complémentaires sur l’évolution microstructurale.Les résultats montrent que le dépôt d’énergie électronique lors d’irradiation simultanée entraîne une diminution de la quantité de défauts ponctuels couplée à une transformation des boucles en lignes de dislocation ce qui minimise l’état de déformation de la couche irradiée. Certains paramètres clefs de ces évolutions ont été identifiés : le taux d’excitation électronique et le niveau d’endommagement initial.Les différentes conditions d’irradiation employées nous ont permis de mieux appréhender l’évolution sous irradiation de l’UO2 et d’une façon plus générale, les phénomènes de couplage intervenant entre les pertes d’énergie électronique et nucléaireDuring in-reactor operation, the nuclear fuel is exposed to the simultaneous radiation of fission fragments, alpha and beta decay, neutrons, etc. UO₂ fuel pellets are the site of a huge damage production, mainly due to the energy loss of fission products. At the atomic scale, low-energy particles lead to formation of collision cascade while the high-energy particles induce electronic excitation and ionisation. Defects such as cavities, dislocation lines and loops are produced in the fuel leading to a microstructural evolution. This evolution may then induce a swelling and/or a restructuration, which can affect the nuclear fuel integrity. Although ballistic and electronic-induced damages are separately well documented, the coupled effects between the two slowing-down processes are not well known.The aim of this study is to characterize these combined effects.Ion irradiations were conducted at the JANNus-Saclay and Orsay facilities with single and dual ion beams. Different complementary techniques were used to describe the microstructural evolution.Results show that both crystalline disorder and strain level are lower under dual-beam irradiation compared to the single one. The electronic energy deposition induce a decrease of point defects quantity as well as a transition from dislocation loops to lines. Some key parameters were highlighted during this study as the electronic excitation rate and the initial damage level.The observed phenomena on uranium dioxide led us to a better understanding of the UO₂ evolution under irradiation and more generally of the specific effects generated by dual-beam irradiations
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Rocha, Rodrigo Tumolin [UNESP]. "On saturation phenomenon in energy harvesting based on nonlinear piezoelectric materials coupled to a portal frame foundation with ideal and non-ideal excitations." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143867.
Повний текст джерелаАнотація:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Recentemente, o interesse e a pesquisa de coleta de energia têm aumentado substancialmente no meio técnico-científico. Com a grande demanda mundial por energia elétrica, muitos pesquisadores, no Brasil e no Mundo, têm concentrado seus esforços na busca de novas fontes de energia. Além disso, com os avanços da tecnologia, é possível utilizar dispositivos de baixo consumo de energia, que são, na maioria das vezes, alimentados por uma bateria, que são fontes de energia finita havendo a necessidade da recarga ou troca periodicamente, das mesmas. No processo de coleta de energia, a energia elétrica é obtida através da conversão de energia mecânica criada por uma fonte de vibração do meio ambiente através de um transdutor. Entre os mais comuns meios de transdução de energia, o uso de materiais piezoelétricos vêm sendo de grande interesse em meio a coleta de energia devido sua facilidade de aplicação e seu uso para coleta de energia em um amplo intervalo de frequências. Fontes de vibração do meio ambiente podem ser causadas em estruturas através do movimento de veículos, um trêm, ondas do mar e até o deslocamento de pessoas. Com isso, este trabalho tem como objetivo estudar a coleta de energia utilizando uma plataforma aporticada não-linear de dois graus de liberdade contendo um material piezoelétrico não-linear acoplado a uma de suas colunas e excitado externamente em sua base. A plataforma não-linear possui ressonância interna 2:1 entre seus modos de vibrar. A não-linearidade do material é considerada através de uma relação matemática não-linear. Além disso, este trabalho será separado em duas partes para a análise das excitações externas. Em sua primeira parte, considera-se uma força harmonica excitando sua base. Na segunda parte, será considerando um vibrador eletrodinâmico com saída harmônica. A metologia empregada para a realização das análises deste trabalho foram: utilizar o método de múltiplas escalas para buscar as melhores configurações dos parâmetros e encontrar fenômenos devido à ressonancia interna 2:1; em seguida foram realizadas excessivas simulações numéricas utilizando o método de Runge-Kutta de quarta e quinta ordem com passo variável buscando otimizar a coleta de energia através da variação de parâmetros, diagramas de bifurcação, expoente de lyapunov, FFTs e históricos no tempo e outros tipos de simulações. Em geral serão feitas duas comparações muito importantes. A influência da não-linearidade do material piezoelétrico e do uso da força harmonica e do vibrador eletrodinâmico na coleta de energia. Os resultados mostraram grande influência da não-linearidade do material piezoelétrico, e utilizando o vibrador foi possível ter um ganho considerável na estabilidade do sistema.
Recently, the interest and research about energy harvesting has been increasing substantially in the technical-scientific community. With the great world demand for electrical energy, many researchers, in Brazil and in the World, have concentrated their efforts to seek new energy sources. In addition, with the technological advances is possible to use low-power consumption devices, that are, most of time, powered by a battery, which are limited energy sources having the necessity of recharging or substituting them periodically. In the energy harvesting process, the electrical energy is obtained through the conversion of mechanical energy created by a vibrating source in the environment using a transducer. Among the most common energy transduction mean, the use of piezoelectric materials has been of great interest in the energy harvesting matter due to its ease of application and its use to harvest energy in a wide range of frequencies. Vibration sources in the environment may occur in structures by vehicle traffics, a train movement, sea waves and even people. With that, the objective of this work is to study the energy harvesting using a nonlinear two-degrees-of-freedom portal frame platform with a nonlinear piezoelectric material coupled to one of its columns and externally base-excited. The nonlinear platform possesses two-to-one internal resonance between its two vibration modes. The nonlinearities of the piezoelectric material is considered as a nonlinear mathematical relation. Moreover, this work is separated in two parts to the analysis of the external excitations. In the first part, a harmonic force base-exciting the system is considered. In the second part is considered an electro-dynamical shaker with harmonic output. The employed methodology to carry out the analysis of this work was: the application of the method of multiple scales to find the best configuration of the parameters, and to find some kind of phenomena due to the two-to-one internal resonance; in the following were carried out several numerical simulations using the method of Runge-Kutta of 4th and 5th order with variable step seeking to optimize the energy harvesting through parametrical variations, bifurcation diagrams, FFTs, time histories and other typos of simulations. In general, it will be done two much important comparisons: the influence of the nonlinearity of the piezoelectric material and the use of the harmonic force and the shaker to the energy harvesting. The results showed great influence of the nonlinearity of the material, and using the electro-dynamical device it was possible to have a considerably gain in the system stability.
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Rocha, Rodrigo Tumolin. "On saturation phenomenon in energy harvesting based on nonlinear piezoelectric materials coupled to a portal frame foundation with ideal and non-ideal excitations /." Bauru, 2016. http://hdl.handle.net/11449/143867.
Повний текст джерелаАнотація:
Orientador: José Manoel BalthazarBanca: Airton Nabarrete
Banca: Angelo Marcelo Tusset
Banca: Vinicius Piccirillo
Banca: Atila Madureira Bueno
Abstract: Recently, the interest and research about energy harvesting has been increasing substantially in the technical-scientific community. With the great world demand for electrical energy, many researchers, in Brazil and in the World, have concentrated their efforts to seek new energy sources. In addition, with the technological advances is possible to use low-power consumption devices, that are, most of time, powered by a battery, which are limited energy sources having the necessity of recharging or substituting them periodically. In the energy harvesting process, the electrical energy is obtained through the conversion of mechanical energy created by a vibrating source in the environment using a transducer. Among the most common energy transduction mean, the use of piezoelectric materials has been of great interest in the energy harvesting matter due to its ease of application and its use to harvest energy in a wide range of frequencies. Vibration sources in the environment may occur in structures by vehicle traffics, a train movement, sea waves and even people. With that, the objective of this work is to study the energy harvesting using a nonlinear two-degrees-of-freedom portal frame platform with a nonlinear piezoelectric material coupled to one of its columns and externally base-excited. The nonlinear platform possesses two-to-one internal resonance between its two vibration modes. The nonlinearities of the piezoelectric material is considered as a nonlinear mathematical r... (Complete abstract click electronic access below)
Resumo: Recentemente, o interesse e a pesquisa de coleta de energia têm aumentado substancialmente no meio técnico-científico. Com a grande demanda mundial por energia elétrica, muitos pesquisadores, no Brasil e no Mundo, têm concentrado seus esforços na busca de novas fontes de energia. Além disso, com os avanços da tecnologia, é possível utilizar dispositivos de baixo consumo de energia, que são, na maioria das vezes, alimentados por uma bateria, que são fontes de energia finita havendo a necessidade da recarga ou troca periodicamente, das mesmas. No processo de coleta de energia, a energia elétrica é obtida através da conversão de energia mecânica criada por uma fonte de vibração do meio ambiente através de um transdutor. Entre os mais comuns meios de transdução de energia, o uso de materiais piezoelétricos vêm sendo de grande interesse em meio a coleta de energia devido sua facilidade de aplicação e seu uso para coleta de energia em um amplo intervalo de frequências. Fontes de vibração do meio ambiente podem ser causadas em estruturas através do movimento de veículos, um trêm, ondas do mar e até o deslocamento de pessoas. Com isso, este trabalho tem como objetivo estudar a coleta de energia utilizando uma plataforma aporticada não-linear de dois graus de liberdade contendo um material piezoelétrico não-linear acoplado a uma de suas colunas e excitado externamente em sua base. A plataforma não-linear possui ressonância interna 2:1 entre seus modos de vibrar. A não-linearidade do... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Wang, Yuchen, Xiushan Zhu, Jie Zong, Kort Wiersma, Arturo Chavez-Pirson, Robert A. Norwood, and N. Peyghambarian. "SESAM Q-switched fiber laser at 1.2 mu m." IEEE, 2016. http://hdl.handle.net/10150/622787.
Повний текст джерелаАнотація:
Q-switched operation of a holmium-doped fluoride fiber laser at 1.2 mu m wavelength induced by a semiconductor saturable absorber mirror (SESAM) is reported. 650 ns pulses with 0.13 mu J pulse energy at a repetition rate of 260 kHz were obtained.
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Nguyen, Tien Minh. "Dynamique non linéaire des systèmes mécaniques couplés: réduction de modèle et identification." Phd thesis, Ecole des Ponts ParisTech, 2007. http://pastel.archives-ouvertes.fr/pastel-00002994.
Повний текст джерелаАнотація:
Le travail présenté dans ce mémoire est une contribution au domaine de l'analyse et de l'identification du comportement dynamique des structures non linéaires. Le premier objectif est la mise au point et la comparaison de quatre techniques de calcul des Modes Normaux Non linéaires (MNNs) : l'approche de Shaw et Pierre, l'approche de Bellizzi et Bouc, l'équilibrage harmonique et la méthode de tir. La combinaison des trois dernières méthodes avec la méthode de continuation permet de détecter les points de bifurcation et de trouver les nouvelles branches de solutions. Le deuxième objectif est l'identification des paramètres caractérisant le comportement dynamique des systèmes linéaires et non linéaires à partir des réponses libres ou des réponses au bruit ambiant. Les outils présentés sur le traitement du signal réel modulé en amplitude et en fréquence par la transformation en ondelettes continue permettent d'atteindre cet objectif. Le dernier objectif est l'extension de la méthode de sous-structuration linéaire de Craig-Bampton au cas non linéaire. Lorsque l'hypothèse de couplage faible entre les sous-structures est faite, le modèle réduit de la structure globale est obtenu par assemblage de modèles réduits de sous-structures avec interfaces de couplage fixe. Ces modèles réduits sont calculés en utilisant l'approche des MNNs de Shaw et Pierre. La robustesse et l'efficacité des méthodes présentées sont étudiées au travers d'exemples numériques ainsi que de tests réels.
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Lombana, Andrés Felipe. "Elaboration d'auto-assemblages supramoléculaires de Donneurs et Accepteurs d'électrons sur Au(111) et leur étude par microscopie à Effet Tunnel couplée à une excitation laser." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC069/document.
Повний текст джерелаАнотація:
Nous présentons l'auto-assemblage 2D de molécules Donneuses (D) et Acceptrices (A) d'électrons sur Au(111), ainsi que leur étude par un dispositif de Microscopie à Effet Tunnel couplé à une excitation lumineuse (LA-STM). Dans un premier temps, des systèmes 2D supramoléculaires robustes (liaisons hydrogène) D et/ou A ont été élaborés par un procédé en solution. Des liaisons hydrogène sont mises en évidence sur un assemblage d'un dérivé de porphyrine (D) pouvant en établir plusieurs, montrant le lien entre les liaisons établies et la géométrie obtenue. D'autre part, un réseau poreux "hôte" à base de molécules de PTCDI (A) et de mélamine est utilisé pour diriger la croissance de molécules "invitées" à l'intérieur des pores. Des systèmes hôte-invités sont alors élaborés en utilisant soit un dérivé thiolé de porphyrine (D), soit un polyoxométalate (POM). Une étude infrarouge de surface (PM-IRRAS) montre en plus que le réseau a une influence différente sur le processus d'organisation des deux molécules.Dans un deuxième temps, la mise en place d'un dispositif de LA-STM est décrite, avec une étude réalisée sur une bicouche moléculaire D/A constituée d'un polymère (PTB7) et d'un dérivé de fullerène (PC71BM). Premièrement, les effets photo-physiques, non spécifiques aux molécules et inhérents à la technique, ont été étudiés. Cela a permis de mesurer le courant à potentiels opposés DI=I(V+)-I(V-), attribué aux transferts de charge aux jonctions D/A. La localisation de ce courant permet d'identifier les jonctions D/A actives en surface avec une résolution nanométriqueWe present the 2D self-assembly of molecular electron Donors (D) and Acceptors (A) on Au(111) and their study by Light-Assisted Scanning Tunneling Microscopy (LA-STM). Firstly, hydrogen bonded supramolecular assemblies are elaborated from solutions. On one hand, a the self-assembly of a porphyrin derivative (D) show the relationship between the established hydrogen bonds and the obtained geometry. On the other hand, a PTCDI-melamine porous host network was used to template the growth of guest molecules within the pores. Host-guest systems are then elaborated using a thiolated porphyrin derivative and a polyoxometalate (POM) molecule. A surface infrared analysis (PM-IRRAS) shows that the network has different effects on the growth process and orientation angles of the two molecules.Secondly, we developed a LA-STM setup and we analysed a polymer/fullerene (PTB7/PC71BM) D/A molecular system. After the study of the photo-physical phenomena giving rise to the photo-current, we measured the current at opposite bias voltages DI=I(V+)-I(V-). We attribute this current to the photo-absorption of the molecules and to the electron transfer at the molecular D/A junctions which allows us to identify the active junctions on the surface with the nanometre resolution
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Zekeng, Serge. "Diffusion Raman par les modes couples phonon-plasmon : application à GaAs dopé Si par implantation ionique : effet de la dose et du mode de recuit thermique." Université Louis Pasteur (Strasbourg) (1971-2008), 1990. http://www.theses.fr/1990STR13077.
Повний текст джерелаАнотація:
Ce travail est consacré à l'étude par diffusion Raman des propriétés de couplage entre ondes mécaniques (phonons) et ondes éléctroniques (plasmons) dans des substrats d'arseniure de gallium (GaAs), implantés avec des impuretés silicium, dans le but d'obtenir des couches dopées n. L'accent est mis sur l'influence de la dose d'implantation (faible ou moyenne) ainsi que sur celle du mode de recuit thermique d'activation (classique ou rapide). Le traitement théorique de la section efficace de diffusion par les modes couples dans gaas-n est presente en premier, suivie d'une revue bibliographique concernant l'implantation silicium dans gaas. Dans la partie experimentale, on insiste surtout sur la détermination des énergies des raies ainsi que de leur profil. Les résultats experimentaux font l'objet d'un chapitre particulier, dans lequel on montre que leur exploitation simplement qualitative est insuffisante pour caractériser les propriétés électriques du cristal. Celles-ci sont obtenue par analyse quantitative du signal Raman dans le cadre d'un modèle simple à deux couches faisant intervenir la zone désertée de surface et la région active sous-jacente. Les résultats des analyses sont discutés et comparés a ceux de la litterature, obtenus par les techniques électriques courantes. Il en ressort que la diffusion Raman est un outil puissant, sélectif, et de plus non destructif, pour l'étude des couches minces dopées ou non.
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El, Fallah Rawa. "Étude des interactions du Benzo(a)pyrène avec les trois fractions physiques de la matière organique du sol par matrices d'excitation et d'émission de fluorescence couplées à PARAFAC." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0034/document.
Повний текст джерелаАнотація:
Les propriétés spectrales des composants fluorescents de la matière organique d’un sol naturel ont été étudiées dans les trois fractions physiques ; substances humiques, acide fulvique et acide humique, par la méthode des matrices d’excitation et d’émission de fluorescence couplée à l’algorithme Parallel Factor analysis (PARAFAC). Les modifications spectrales de ces composants ont été suivies (forme et pseudo-concentrations) en présence d’un contaminant de type hydrocarbure aromatique polycyclique (le benzo(a)pyrène (BaP), toxique et à caractère cancérigène) : (1) en faisant varier les volumes d’une solution pure de BaP dans chaque fraction de même concentration en matières organiques, (2) en faisant varier les concentrations en matière organique pour des concentrations fixes de BaP, qui ont été suivies dans le temps. Les résultats ont montré que le BaP influence d’une manière différente les fluorophores présents dans les trois fractions et ont permis de clarifier le type d’interactions avec une fraction ou l’autre. D’autre part, une discussion a été menée sur les paramètres de validation du nombre de composants pour le choix des modèles de PARAFACThe spectral properties of the fluorescent components of the organic matter of a natural soil were studied in the three physical fractions; humic substances, fulvic acid and humic acid, by the method of the excitation and fluorescence emission matrices coupled to the Parallel Factor Analysis (PARAFAC) algorithm. The spectral modifications of these components were studied (form and pseudo-concentrations) in the presence of a polycyclic aromatic hydrocarbon contaminant (benzo (a) pyrene (BaP), toxic and carcinogenic): (1) by varying the volumes of a pure solution of BaP in each fraction having the same concentration of organic matter, (2) by varying the concentrations of organic matter for fixed concentrations of BaP, which were followed over time. The results showed that the BaP influences the fluorophores present in the three fractions in a different way and clarified the type of interactions with one fraction or the other. On the other hand, a discussion was held on parameters for validating the number of components for the selection of PARAFAC models
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Šikl, Tomáš. "Modelování dielektrických směrových odbočnic." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219120.
Повний текст джерелаАнотація:
Dielectric High-frequency transmission lines are natural alternative to the lines made of metal in term of low loss. These lines are mainly used in microwave techniques of measuring. The main object is to describe basic parameters of metal and dielectric transmission lines and their comparison. Next point is a basic overview of the excitation the lines from metal and it's application on dielectric transmission lines. Then make the simulation of microstrip directional couplers and coupler made by dielectric waveguides. The last point of work is construction these directional couplers and measuring their most important parameters.
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Beckstein, Pascal. "Methodenentwicklung zur Simulation von Strömungen mit freier Oberfläche unter dem Einfluss elektromagnetischer Wechselfelder." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232474.
Повний текст джерелаАнотація:
Im Bereich der industriellen Metallurgie und Kristallzüchtung treten bei zahlreichen Anwendungen, wo magnetische Wechselfelder zur induktiven Beeinflussung von leitfähigen Werkstoffen eingesetzt werden, auch Strömungen mit freier Oberfläche auf. Das Anwendungsspektrum reicht dabei vom einfachen Aufschmelzen eines Metalls in einem offenen Tiegel bis hin zur vollständigen Levitation. Auch der sogenannte RGS-Prozess, ein substratbasiertes Kristallisationsverfahren zur Herstellung siliziumbasierter Dünnschichtmaterialien, ist dafür ein Beispiel. Um bei solchen Prozessen die Interaktion von Magnetfeld und Strömung zu untersuchen, ist die numerische Simulationen ein wertvolles Hilfsmittel. Für beliebige dreidimensionale Probleme werden entsprechende Berechnungen bisher durch eine externe Kopplung kommerzieller Programme realisiert, die für Magnetfeld und Strömung jeweils unterschiedliche numerische Techniken nutzen. Diese Vorgehensweise ist jedoch im Allgemeinen mit unnötigem Rechenaufwand verbunden. In dieser Arbeit wird ein neu entwickelter Methodenapparat auf Basis der FVM vorgestellt, mit welchem sich diese Art von Berechnungen effizient durchführen lassen. Mit der Implementierung dieser Methoden in foam-extend, einer erweiterten Version der quelloffenen Software OpenFOAM, ist daraus ein leistungsfähiges Werkzeug in Form einer freien Simulationsplattform entstanden, welches sich durch einen modularen Aufbau leicht erweitern lässt. Mit dieser Plattform wurden in foam-extend auch erstmalig dreidimensionale Induktionsprozesse im Frequenzraum gelöst.