To see the other types of publications on this topic, follow the link: Open waveguides.
Dissertations / Theses on the topic 'Open waveguides'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 27 dissertations / theses for your research on the topic 'Open waveguides.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Vasilevskaya, Elizaveta. "Open periodic waveguides : Theory and computation." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCD008/document.
Full textAbstract:
Cette thèse porte sur la propagation des ondes acoustiques dans des milieux périodiques.Ces milieux ont des propriétés remarquables car le spectre associée à l’opérateur d’ondesdans ces milieux a une structure de bandes : il existe des plages de fréquences danslesquelles les ondes monochromatiques ne se propagent pas. Plus intéressant encore, enintroduisant des défauts linéiques dans ce type de milieux, on peut créer des modes guidésà l’intérieur de ces bandes de fréquences interdites. Dans ce manuscrit nous montrons qu’ilest possible de créer de tels modes guidés dans le cas de milieux périodiques particuliersde type quadrillage : plus précisément, le domaine périodique considéré est constitué duplan R2 privé d’un ensemble infini d’obstacles rectangulaires régulièrement espacés (d’unedistance ") dans deux directions orthogonales du plan, que l’on perturbe localement endiminuant la distance entre deux colonnes d’obstacles. Les résultats sont ensuite étendusau cas 3D.Ce travail comporte un aspect théorique et un aspect numérique. Du point de vue théoriquel’analyse repose sur le fait que, comme " est petit, le spectre de l’opérateur associé ànotre problème est "proche" du spectre d’un problème posé sur le graphe obtenu commela limite géométrique du domaine quand " tend vers 0. Or, pour le graphe limite, il estpossible de calculer explicitement le spectre. Ensuite, en utilisant des méthodes d’analyseasymptotique on étudie le spectre de l’opérateur non-limite. On illustre les résultats théoriquespar des résultats numériques obtenus à l’aide d’une méthode numérique spécialementdédiée aux milieux périodiques : cette dernière est basée sur la réduction du problèmede valeurs propres initial (linéaire) posé dans un domaine non-borné à un problème nonlinéaireposé dans un domaine borné (en utilisant l’opérateur de Dirichlet-to-Neumannexact)The present work deals with propagation of acoustic waves in periodic media. Thesemedia have particularly interesting properties since the spectrum associated with theunderlying wave operator in such media has a band-gap structure: there exist intervals offrequences for which monochromatic waves do not propagate. Moreover, by introducinglinear defects in this kind of media, one can create guided modes inside the bands offorbidden frequences. In this work we show that it is possible to create such guidedmodes in the case of particular periodic media of grid type: more precisely, the periodicdomain in question is R2 minus an infinite set of rectangular obstacles periodically spacedin two orthogonal directions (the distance between two neighbour obstacles being "),which is locally perturbed by diminishing the distance between two columns of obstacles.The results are extended to the 3D case.This work has a theoretical and a numerical aspect. From the theoretical point of view theanalysis is based on the fact that, " being small, the spectrum of the operator associatedwith our problem is "close" to the spectrum of a problem posed on a graph which is ageometric limit of the domain as " tends to 0. However, for the limit graph the spectrumcan be computed explicitly. Then, we study the spectrum of the non-limit operatorusing asymptotic analysis. Theoretical results are illustrated by numerical computationsobtained with a numerical method developed for study of periodic media: this method isbased on the reduction of the initial (linear) eigenvalue problem posed in an unboundeddomain to a non-linear problem posed in a bounded domain (using the exact Dirichletto-Neumann operator)
2
McDougall, Marc J. "Infinite elements for the analysis of open dielectric waveguides." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64088.
Full text
3
Chang, C. S. "A rigorous analysis of cascaded step discontinuities in open waveguides." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317348.
Full text
4
Law, Hong-Tat Philip. "Analysis of electromagnetic scattering by open-ended waveguides containing complex obstacles /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu148768520496745.
Full text
5
Ott, Julian [Verfasser], and A. [Akademischer Betreuer] Kirsch. "Halfspace Matching: a Domain Decomposition Method for Scattering by 2D Open Waveguides / Julian Ott ; Betreuer: A. Kirsch." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/113602171X/34.
Full text
6
Leclerc, Augustin. "Calculs de mοdes électrοmagnétiques guidés dans des guides d'οndes tοrsadés et οuverts." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR28.
Full textAbstract:
Cette thèse explore la modélisation et le calcul des modes électromagnétiques (EM) dans des guides d'ondes de géométries complexes, notamment dans des câbles électriques torsadés en milieux ouverts. L'objectif est de développer des méthodes numériques pour résoudre les équations de Maxwell afin de mieux comprendre la propagation des champs électromagnétiques dans des configurations réalistes. Cette étude est motivée par les enjeux liés à la réduction du rayonnement électromagnétique et à l'amélioration des performances des câbles en termes de confinement des champs. Nous traitons deux principales configurations : les guides d’ondes droits et les guides d'ondes torsadés. Pour les guides droits, des méthodes semi-analytiques sont mises en œuvre, notamment pour les câbles coaxiaux, permettant de tester les modèles numériques. Nous étendons ces méthodes aux guides d'ondes ouverts, où des conditions aux limites absorbantes (CLA) sont introduites pour modéliser un environnement infini en limitant les réflexions parasites. Dans les câbles torsadés, une géométrie hélicoïdale est exploitée afin de reformuler les équations de propagation des ondes EM dans un cadre numérique adapté, permettant d'obtenir des simulations en basse fréquence. Un travail sur la construction de CLA dans ce cadre a également été initié. Les résultats obtenus fournissent une meilleure compréhension des phénomènes électromagnétiques à basse fréquence et ouvrent des perspectives pour la conception de dispositifs plus performants et l'étude des systèmes électromagnétiques dans des environnements hétérogènes réelsThis thesis explores the modelling and calculation of electromagnetic (EM) modes in waveguides with complex geometries, particularly in twisted electric cables in open environments. The aim is to develop numerical methods for solving Maxwell's equations in order to better understand the propagation of electromagnetic fields in realistic configurations. This study is motivated by the challenges of reducing electromagnetic radiation and improving cable performance in terms of field containment. We deal with two main configurations: straight waveguides and twisted waveguides. For straight waveguides, semi-analytical methods are used, particularly for coaxial cables, to test numerical models by comparison with precise solutions. We extend these methods to open waveguides, where absorbing boundary conditions (ABC) are introduced to model an infinite environment while limiting spurious reflections. In twisted cables, a helical geometry is exploited to reformulate the EM wave propagation equations in a suitable numerical framework, enabling low-frequency simulations to be obtained. Work on the construction of ABCs within this framework has also been initiated. The results that we obtain provide a better understanding of low-frequency electromagnetic phenomena and open up prospects for the design of more efficient devices and the study of electromagnetic systems in real heterogeneous environments
7
Sibbald, Christopher L. "Open-ended waveguide structures." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5576.
Full text
8
Altintas, Ayhan. "Electromagnetic Scattering from a Class of Open-Ended Waveguide Discontinuities." Connect to resource, 1986. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1208793684.
Full text
9
Fitzmaurice, Michael G. "A new finite-difference time-domain method applied to an open waveguide structure." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7950.
Full textAbstract:
The study makes use of a variation of the Finite-Difference Time-Domain (FDTD) method as first proposed by Yee to simulate electromagnetic field distribution and propagation in an open waveguide structure. In order to prove that this new method is valid, a reflection coefficient is calculated with simulation data and compared to measurements. The agreement between measurement and simulation data, while not exact, is enough to establish the veracity of the new method. This study contains a detailed discussion of the discrepancies which were observed. Also presented are colour images of the simulation which give the reader an idea as to the nature and level of detail of the information which can be obtained from the simulation.
10
Burkholder, Robert J. "High-frequency asymptotic methods for analyzing the EM scattering by open-ended waveguide cavities /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487599963593742.
Full text
11
Fritsch, Jean-François. "Propagation des ondes dans les guides partiellement enfouis : résolution du problème direct et imagerie par méthode de type échantillonnage." Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAE001.
Full textAbstract:
Ce travail de thèse porte sur le contrôle non destructif de structures élancées partiellement enfouies ou immergées, par exemple un câble d'acier partiellement enfoui dans du béton ou une plaque d'acier partiellement immergée dans du sodium liquide. Ces structures peuvent être vues comme la jonction d'un guide fermé et d'un guide ouvert. Pour effectuer des calculs, nous avons tronqué transversalement la partie ouverte de la structure avec des PML finies. Un guide partiellement enfoui peut alors être traité comme la jonction de deux guides fermés, dont la propagation des ondes dans l'un des guides est régie par une équation impliquant des coefficients complexes liés à la présence des PML. Ce constat nous a amené à commencer par traiter dans un premier temps le cas plus simple de la jonction de deux guides acoustiques fermés. Pour ce cas simple, nous avons proposé une démarche de résolution du problème inverse adaptée aux jonctions de guides d'ondes fermés. Elle repose d'une part sur l'introduction des champs de référence, qui sont les réponses de la structure totale sans défaut à un mode provenant d'un des deux demi-guides, et d'autre part sur l'utilisation de la relation de réciprocité de la fonction de Green de la structure sans défaut. Suivant cette démarche, nous avons obtenu une formulation modale efficace de la LSM qui nous a permis d'identifier des défauts. Dans ce cas simple, nous avons tiré parti de la complétude des modes pour analyser les problèmes direct et inverse. Dans un second temps, nous avons traité le cas d'un guide acoustique partiellement enfoui. La perte de complétude des modes dans le demi-guide tronqué transversalement avec des PML nous a amenée à étudier le problème direct à l'aide de la théorie de Kondratiev. Les outils introduits pour la jonction de deux guides fermés ont été ensuite adaptés à la résolution du problème inverse. Dans un troisième temps, nous avons abordé le cas plus réaliste, mais plus complexe, d'un guide élastique partiellement immergé dans un fluide. Pour ce cas difficile, nous avons développé des outils de simulation adaptés et étendus les outils introduits précédemment pour résoudre le problème inverseThis work is about the non destructive testing of partially buried or immersed slendered structures such as a steel cable partially buried in concrete or a steel plate partially immersed in liquid sodium. Such structures can be seen as the junction of two closed waveguides. In order to perform computing, the open part of the structure is truncated in the transverse direction with PMLs. As a result, a partially buried waveguide can be treated as the junction of two closed waveguides, in one of which the propagation of waves is governed by an equation involving complex coefficients due to the presence of the PMLs. This observation has lead us to tackle first the simpler case of the junction of two closed acoustic waveguides. For this simple case, we have proposed a strategy to solve the inverse problems based on the one hand on the introduction of the so-called reference fields, which are the total field response of the structure without defects to an incident field coming frome both half-guides, and on the other hand on the use of the reciprocity of the Green function of the structure without defect. Following this strategy, we have obtained an efficient modal formulation of the LSM which has enabled us to retrieve defects. In this simple case, we have taken advantage of the completeness of the modes to analyze the forward and inverse problems. The loss of the completeness of the modes in the half-guide truncated in the transverse direction with PMLs has led us to study the forward problem with Kondratiev theory. The tools introduced for the junction of two closed waveguides have been adapted to solve the inverse problem. Finally, we have tackled the more complex, but more realsitic case of an elastic waveguide partially immersed in a fluid. For this difficult case, we have developped adapted computing tools adapted and extended the tools introduced before solving the inverse problem
12
Sibbald, Christopher L. "A new technique for modeling open-ended waveguide structures and its application to dielectric spectroscopy." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7808.
Full textAbstract:
A novel technique for modeling the aperture admittance of open-ended waveguide structures radiating into a homogeneous, lossy dielectric half-space is presented. This technique combines both analytical and numerical approaches to express the aperture admittance as rational function of frequency and the relative permittivity of the external medium. The coefficients of the rational approximation, which depend upon the geometry of the waveguide and aperture, are determined in a very convenient manner from a relatively small number of computed admittances. This computed data is obtained via a full-wave movement method solution and, hence, includes the effects of radiation and energy storage in the near-field and evanescent waveguide modes. The accuracy of the numerical method is demonstrated by comparison with measured values. The new technique is successfully applied to obtain a model for the open-ended coaxial line geometry. The new model has important applications in the field of dielectric spectroscopy. In addition to yielding accurate solutions for the aperture admittance of the line as a function of the permittivity of the external medium, the model yields a unique solution to the inverse problem and permits a rigorous sensitivity and uncertainty analysis.
13
Eade, James C. "Investigation of open periodic structures of circular cross section and their transition to solid circular waveguide." Thesis, Loughborough University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394873.
Full text
14
Gasi, Jasmin. "Design, Fabrication and Validation of High-permittivity Low-loss Microwave Material for Biomedical Sensor." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-364035.
Full textAbstract:
Abstract The purpose of this task is to synthesize a dielectric substrate material through a sintering process, which can be used for non-invasive physiological sensor development. Low loss, high dielectric constant ceramic material is used. Sintering process is employed to ensure stable structure and homogeneous dielectric properties of the substrate. Samples were prepared with TiO2 and in combination with CuO and Al2O3. All samples were measured and validated in 500 MHz to 20 GHz frequency range. Characterization measurements were performed with a Vector Network Analyzer, FieldFox N9918A, and connected to Keysight, open ended coaxial probe and performance probe. Reflection based measurement method was used due to its simplicity, speed and requirement of wideband data. The dielectric measurement results of developed samples show non-frequency dispersive behaviour, high dielectric constant and data was also selected at 2.45 GHz in aligned to the industrial, scientific and medical band. The resulting measurements show the highest dielectric constant of 16.6 at 2.45 GHz with a very low loss behaviour.Målet är att syntetisera ett material, genom sintringsprocess, som kan användas som ett dielektriskt substrat för utveckling av sensorer. Det dielektriska materialet har keramisk materialstruktur och innehar högt dielektricitetskonstant med låga dielektriska materialförluster. Denna uppgift kräver att dielektriska materialet ska vara stabilt och inneha isotropiska egenskaper efter att genomgått sintringsprocess. Proverna förberedes med TiO2 och även i kombination med TiO2 tillsammans med CuO och Al2O3. Proverna mäts i frekvensområdet 500 MHz till 20 GHz. Mätningarna utförs med Vector Network Analyzer, FieldFox N9918A från Keysight. Resultat som visas och jämförs i arbetet är tagna vid 2.45 GHz eftersom det används och är standardiserat för medicinskt frekvensband. Högsta uppmätta dielektricitetskonstant har värdet av 16,6. Resultaten visar även låga förluster i dielektrikumet.
15
Habash, Riadh W. Y. "Non-Invasive Microwave Hyperthermia." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/193.
Full textAbstract:
Presented in this thesis are the following theoretical investigations carried out on the non-invasive microwave hyperthermia of malignant tumours in the human body:
Fundamental concepts of electromagnetic wave propagation through a biomass and its interaction with it, are discussed. Various types of applicators used for producing hyperthermia in a biomass, are also discussed.
Propagation of a uniform plane electromagnetic wave through a human body is investigated for the general case of oblique incidence. Various models used for the human body have been discussed and the planar multilayer model has been chosen for this study. Reflection and transmission coefficients for both the parallel and perpendicular linear polarisations of the wave, have been determined. For normal incidence, power transfer ratio at the muscle has been defined and calculated at 433, 915 and 2450 MHz (ISM frequencies).
Efects of skin thickness and also of fat thickness, on the power transfer ratio at muscle, have been studied. Effects of the thickness and dielectric constant of a bolus, and also of the dielectric constant of an initial layer, on the power transfer ratio, have been studied and their optimum values obtained at the ISM frequencies. For microwave hyperthermia, 915 MHz is recommended as the frequency of operation.
Steady-state solution of the bioheat transfer equation has been obtained, assuming the biomass to be a semi-infinite homogeneous medium. Effects of various physical parameters on the temperature profile in the biomass, have been studied. Also studied is the effect of the surface temperature on the magnitude, location and the width of the temperature peak attained in the biomass. A method to determine the microwave power and the surface temperature required to produce a prescribed temperature profile in the biomass, has been developed. The transient-state solution of the bioheat transfer equation has been obtained to study the building up of the temperature profile.
Procedures for the design of an open-ended rectangular metal waveguide applicator and for estimating the total microwave power requirement to produce hyperthermia in the human body, have been developed. Performance of the applicators employing linear as well as planar arrays of open-ended rectangular metal waveguide antennas, has also been studied. In order to reduce the overall physical size of the applicators, filling up of the feed waveguide with a high dielectric constant but low loss material is suggested. A simple method of obtaining the elements of the array by partitioning a large aperture by using metal walls has been adopted. Calculation of the total microwave power required by various applicators for producing hyperthermia at various depths in a biomas, have been made and a comparison of the performance of various applicators, has been presented.
16
Habash, Riadh W. Y. "Non-Invasive Microwave Hyperthermia." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/193.
Full textAbstract:
Presented in this thesis are the following theoretical investigations carried out on the non-invasive microwave hyperthermia of malignant tumours in the human body:
Fundamental concepts of electromagnetic wave propagation through a biomass and its interaction with it, are discussed. Various types of applicators used for producing hyperthermia in a biomass, are also discussed.
Propagation of a uniform plane electromagnetic wave through a human body is investigated for the general case of oblique incidence. Various models used for the human body have been discussed and the planar multilayer model has been chosen for this study. Reflection and transmission coefficients for both the parallel and perpendicular linear polarisations of the wave, have been determined. For normal incidence, power transfer ratio at the muscle has been defined and calculated at 433, 915 and 2450 MHz (ISM frequencies).
Efects of skin thickness and also of fat thickness, on the power transfer ratio at muscle, have been studied. Effects of the thickness and dielectric constant of a bolus, and also of the dielectric constant of an initial layer, on the power transfer ratio, have been studied and their optimum values obtained at the ISM frequencies. For microwave hyperthermia, 915 MHz is recommended as the frequency of operation.
Steady-state solution of the bioheat transfer equation has been obtained, assuming the biomass to be a semi-infinite homogeneous medium. Effects of various physical parameters on the temperature profile in the biomass, have been studied. Also studied is the effect of the surface temperature on the magnitude, location and the width of the temperature peak attained in the biomass. A method to determine the microwave power and the surface temperature required to produce a prescribed temperature profile in the biomass, has been developed. The transient-state solution of the bioheat transfer equation has been obtained to study the building up of the temperature profile.
Procedures for the design of an open-ended rectangular metal waveguide applicator and for estimating the total microwave power requirement to produce hyperthermia in the human body, have been developed. Performance of the applicators employing linear as well as planar arrays of open-ended rectangular metal waveguide antennas, has also been studied. In order to reduce the overall physical size of the applicators, filling up of the feed waveguide with a high dielectric constant but low loss material is suggested. A simple method of obtaining the elements of the array by partitioning a large aperture by using metal walls has been adopted. Calculation of the total microwave power required by various applicators for producing hyperthermia at various depths in a biomas, have been made and a comparison of the performance of various applicators, has been presented.
17
Gallezot, Matthieu. "Simulation numérique du contrôle non-destructif des guides d’ondes enfouis." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0040/document.
Full textAbstract:
De nombreux éléments de structures de génie civil sont élancés et partiellement enfouis dans un milieu solide. Les ondes guidées sont souvent utilisées pour le contrôle non destructif (CND) de ces éléments. Ces derniers sont alors considérés comme des guides d’ondes ouverts, dans lesquels la plupart des ondes sont atténuées par des fuites dans le milieu environnant. D’autre part le problème est non borné, ce qui le rend difficile à appréhender sur le plan numérique. La combinaison d’une approche par éléments finis semi-analytique (SAFE) et de la méthode des couches parfaitement adaptées (PML) a été utilisée dans une thèse antérieure pour calculer numériquement trois types de modes (modes piégés, modes à fuite et modes de PML). Seuls les modes piégés et à fuite sont utilisés pour la représentation des courbes de dispersion. Les modes de PML sont non intrinsèques à la physique. L’objectif premier de cette thèse est d’obtenir, par superposition modale sur les modes calculés, les champs émis et diffracté dans les guides d’ondes ouverts. Nous montrons dans un premier temps que les trois types de modes appartiennent à la base modale. Une relation d’orthogonalité est obtenue dans la section du guide(incluant la PML) pour garantir l’unicité des solutions. La réponse forcée du guide peut alors être calculée rapidement par une somme sur les modes en tout point du guide. Des superpositions modales sont également utilisées pour construire des frontières transparentes au bord d’un petit domaine élément fini incluant un défaut, permettant ainsi de calculer le champ diffracté. Au cours de ces travaux, nous étudions les conditions d’approximation des solutions par des superpositions modales, limitées seulement aux modes à fuite, ce qui permet de réduire le coût des calculs. De plus, la généralité des méthodes proposées est démontrée par des calculs hautes fréquences (intéressantes pour le CND) et sur des guides tridimensionnels. Le deuxième objectif de cette thèse est de proposer une méthode d’imagerie pour la localisation de défauts. La méthode de l’imagerie topologique est appliquée aux guides d’ondes. Le cadre théorique général, de type optimisation sous contrainte, est rappelé. Le formalisme modal permet un calcul rapide de l’image. Nous l’appliquons pour simuler un guide d’onde endommagé, et nous montrons l’influence du type de champ émis (monomodal, dispersif,multimodal) ainsi que des configurations de mesure sur la qualité de l’image obtenueVarious elements of civil engineering structures are elongated and partially embedded in a solid medium. Guided waves can be used for the nondestructive evaluation (NDE) of such elements. The latteris therefore considered as an open waveguide, in which most of waves are attenuated by leakage losses into the surrounding medium. Furthermore, the problem is difficult to solve numerically because of its unboundedness. In aprevious thesis, it has been shown that the semi-analytical finite-element method (SAFE) and perfectly matched layers(PML) can be coupled for the numerical computation of modes. It yields three types of modes: trapped modes,leaky modes and PML modes. Only trapped and leaky modes are useful for the post-processing of dispersion curves. PML modes are non-intrinsic to the physics. The major aim of this thesis is to obtain the propagated and diffracted fields, based on modal superpositions on the numerical modes. First, we show that the three types of modes belong to the modal basis. To guarantee the uniqueness of the solutions an orthogonality relationship is derived on the section including the PML. The forced response can then be obtained very efficiently with a modal expansion at any point of the waveguide. Modal expansions are also used to build transparent boundaries at the cross-sections of a small finite-element domain enclosing a defect, thereby yielding the diffracted field. Throughout this work, we study whether solutions can be obtained with modal expansions on leaky modes only, which enables to reduce the computational cost. Besides, solutions are obtained at high frequencies (which are of interest for NDE) and in tridimensional waveguides, which demonstrates the generality of the methods. The second objective of this thesis is to propose an imaging method to locate defects. The topological imaging method is applied to a waveguide configuration. The general theoretical framework is recalled, based on constrained optimization theory. The image can be quickly computed thanks to the modal formalism. The case of a damaged waveguide is then simulated to assess the influence on image quality of the emitted field characteristics (monomodal, dispersive or multimodal)and of the measurement configuration
18
Mora, Pierric. "Réponse élastodynamique d'une plaque stratifiée anisotrope : approches comparées. : Vers le développement de méthodes hybrides." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0382/document.
Full textAbstract:
Cette thèse traite de la résolution du problème direct de propagation d'un champ élastodynamique rayonné par une source dans un milieu stratifié anisotrope. Le contexte applicatif visé est le contrôle non destructif par ondes ultrasonores guidées de plaques de matériaux composites. Aux basses fréquences, ces matériaux sont assimilables à des milieux homogènes, anisotropes et dissipatifs. Deux approches causales sont étudiées et mises en oeuvre pour résoudre l'équation d'onde, et leur intérêt vis-à-vis de la méthode modale harmonique - la plus couramment employée dans ce domaine applicatif - est discuté. L'une des méthodes est modale et est formulée directement dans le domaine temporel. Elle permet de traiter facilement l'anisotropie, y compris en 3D, mais souffre des écueils classiques concernant le régime non-établi ou le cas du guide ouvert. L'autre approche est une formulation dans le domaine de Laplace de la méthode dite par ondes partielles. Elle présente l'intérêt d'être extrêmement polyvalente tout en conduisant à des coûts numériques tout à fait raisonnables. Dans un second temps, la possibilité d'exploiter ces deux méthodes pour résoudre des problèmes de diffraction par des défauts est étudiée. Une approche par éléments finis de frontière basée sur la méthode par ondes partielles est considérée. Elle permet de traiter efficacement le cas de défauts plans. L'extension à des défauts plus généraux est brièvement discutéeThis work adresses the direct problem of the propagation of an elastodynamic field radiated by a source in an anisotropic layered medium. Applications concern non destructive evaluation of composite plates by ultrasonic guided waves. In the lower frequencies, these materials can be modeled as homogeneous, anisotropic and dissipative media. Two causal approaches are studied and developped to solve the wave equation, and their interest is discussed regarding to the widely used harmonic modal method. One of these methods is modal, and is formulated directly in the time domain. It allows to deal easily with anisotropy, even in 3D ; however it also suffers classical shortcomings such as the high cost of the unestablished regime or the difficulty to deal with open waveguides. The other method is a formulation of the so-called partial-waves method in the Laplace domain. Its attractiveness relies in its versatility and in the fact that computational costs can be very acceptable. In a second time, we consider using both methods to solve problems of diffraction by defects. A boundary element method based on the partial-waves approach is developped and leads to solve very efficiently the case of a planar defect. The possibility of treating more general defects is briefly discussed
19
Sheen, Jyh-Wen, and 沈志文. "Characterization of Coplanar Waveguide Open-End and Short-End." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/23234768692653276650.
Full textAbstract:
碩士國立交通大學
電信研究所
81
This thesis describes a rigorous numerical approach for characterizing coplanar waveguide discontinuities. The method in the thesis employs the moment method to find the unknown electric field distribution on the slot apertures and subsequently the scattering parameter of the discontinuities. In this approach coplanar waveguide open-end and short-end discontinuities are investigated by the spectral domain integral equation method. Surface wave and radiation effects are properly included in the analysis method. The numerical results obtained are validated by comparing with experimental data and numerical data in the literature.
20
MAO, MING-HUA, and 毛明華. "Capacitance analysis for coplanar waveguide and its open end structure." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/31318972295539179718.
Full text
21
Chang, Fu-Yuan, and 張富淵. "A Study on Coplanar Waveguide Bandpass Filter Using Open-Circuited Stubs." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/85879093308959543950.
Full text
22
LEE, I.-SHU, and 李一書. "A STUDY ON COPLANAR WAVEGUIDE LOWPASS FILTER USING OPEN CIRCUIT STUBS." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/00531836347184649275.
Full textAbstract:
碩士國立海洋大學
電機工程學系
85
IN THE DESIGN OF LOWPASS FILTER, THE CUTOFF FREQUENCY, THE INSERTION AND RETURN LOSSES IN THE PASSBAND, AND THE ATTENUATION SLOPS IN THE STOPBAND ARE IMPORTANT PARAMETERS TO BE CONSIDERED. MOREOVER, THEPERFORMANCES OF FILTERS CAN BE IMPROVED BY USING THE PLANAR STRUCTURES. IN THIS THESIS, THE CONDUCTOR-BACKED COPLANAR WAVEGUIDE STRUCTURESARE USED TO DESIGN THE LOEPASS FILTERUSING OPEN CIRCUIT STUBS. IN THIS THESIS, THE THEORY OF THE DESIGN OF LOWPASS FILTER IS ANALYZED FIRSTLY. NEXT,THE COPLANAR WAVEGUIDE LOWPASS FILTER WITH CROSS- AND T- IUNCTIONDISCONTINUITIES ARE DESIGNED AND REALIZED, RESPECTIVELY. MOREOVER, THE EFFECTOF COPLANAR WAVEGUIDE CROSS- AND T-JUNCTION DISCONTINUOUS ARE STUDIED AND COMPENSATEDPROPERLY. FINALLY, THE CHARACTERISTICS OF THE FILTERS ARE MEASURED AND IMPROVED BY THE SUGGESTED METHOD.
23
Correia, Davi. "A higher-order perfectly matched layer for open-region, waveguide, and periodic electromagnetic problems /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3250229.
Full textAbstract:
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1171. Adviser: Jianming Jin. Includes bibliographical references (leaves 100-104) Available on microfilm from Pro Quest Information and Learning.
24
Yi-Cong, Iv, and 呂易璁. "Analysis of Coupling Calibration for Electric Field Probe Applied to SAR Measurement Using a Adjustable Open-ended Waveguide." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/86461999763671424741.
Full textAbstract:
碩士大葉大學
電信工程學系碩士班
94
In the recent years, （Specific Absorption Rate）SAR has become an important issue concerning health hazard due to the rising usage of wireless communication technologies. The measurement system mostly used the E-Probe to measure the SAR values. However the E-Probe offer extended usage will gradually degrade in term of precision and accuracy. Since, to date, there exists no Laboratories in this country to perform the calibration, it would be of interest to design such a calibration scheme. The implementation of the local calibration will not only save time but also the huge expenses of sending the E-Probe to the original manufacturer for recalibration. In this thesis, to design of system for the calibration of SAR probe is carried not under two environments, namely, in air and tissue. A waveguide operating in the desired calibration frequency was designed. The fabricated waveguide was constructed with an adjustable short-circuited termination. For the calibration in air, the E-Probe was placed in the center of the waveguide aperture and gradually extended inwardly. To record the measured SAR values. However, when calibrating in the tissue equivalent-liquid, a Teflon container filled with the tissue equivalent liquid was placed on the top of the interior of the waveguide. The E-Probe was then positioned in the center of the Teflon container and raises the E-Probe from the bottom of the container slowly. In this study, we have utilized electromagnetic numerical simulation method to compare the measurement values to verify the accuracy of the result. We focused on the analysis and comparison related to the E-field distribution at 900MHz and 1800MHz.
25
Nie, Guo Qiang, and 聶國強. "FDTD analysis of radiation into lossy multi-layered half-space from an open-ended rectangular waveguide with grounded side wall and its application on microwave radiometry." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/75320957775353827063.
Full text
26
Kallol, Roy. "Quantum Algorithmic Engineering with Photonic Integrated Circuits." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3451.
Full textAbstract:
Integrated quantum photonics show monolithic waveguide chips to be a promising platform for realizing the next generation of quantum optical circuits. This work proposes the implementation of quantum page Rank algorithm on a photonic waveguide lattice. Our contributions are as follows: Continuous-time quantum stochastic walk(QSW)-an alternate paradigm of quantum computing, is a hybrid quantum walk that incorporates both unitary and non-unitary effects. We propose the use of QSW which necessitates the hopping of the quantum crawler on a directed graph, for the quantum page Rank problem. We propose the implementation of quantum page Rank on a photonic waveguide lattice, where we allow the density matrix to evolve according to the Lindblad-Kossakowski master equation, the diagonal of which gives the quantum page Rank. We have also shown the use of the metric of positional Kolmogorov Complexity as an efficient tool for determining whether or not the quantum channel has been compromised. We appositionally encode multi-photon decoy pulses within the stream of single photon pulses. This positional encoding is chosen in such a way as to have low Kolmogorov complexity. The PNS attack on the multi-photon decoy pulses causes a dip in the ratio of the transmittance of the decoy pulses to the signal pulses in the conventional analysis.
27
Kallol, Roy. "Quantum Algorithmic Engineering with Photonic Integrated Circuits." Thesis, 2013. http://etd.iisc.ernet.in/2005/3451.
Full textAbstract:
Integrated quantum photonics show monolithic waveguide chips to be a promising platform for realizing the next generation of quantum optical circuits. This work proposes the implementation of quantum page Rank algorithm on a photonic waveguide lattice. Our contributions are as follows: Continuous-time quantum stochastic walk(QSW)-an alternate paradigm of quantum computing, is a hybrid quantum walk that incorporates both unitary and non-unitary effects. We propose the use of QSW which necessitates the hopping of the quantum crawler on a directed graph, for the quantum page Rank problem. We propose the implementation of quantum page Rank on a photonic waveguide lattice, where we allow the density matrix to evolve according to the Lindblad-Kossakowski master equation, the diagonal of which gives the quantum page Rank. We have also shown the use of the metric of positional Kolmogorov Complexity as an efficient tool for determining whether or not the quantum channel has been compromised. We appositionally encode multi-photon decoy pulses within the stream of single photon pulses. This positional encoding is chosen in such a way as to have low Kolmogorov complexity. The PNS attack on the multi-photon decoy pulses causes a dip in the ratio of the transmittance of the decoy pulses to the signal pulses in the conventional analysis.