Dissertations / Theses on the topic 'Leaky modes'

In the absence of external excitation, light trapped within a dielectric medium generally decays by leaking out-and also by getting absorbed within the medium. We analyze the leaky modes of a parallel-plate slab, a solid glass sphere, and a solid glass cylinder, by examining those solutions of Maxwell's equations (for dispersive as well as non-dispersive media) which admit of a complex-valued oscillation frequency. Under certain circumstances, these leaky modes constitute a complete set into which an arbitrary distribution of the electromagnetic field residing inside a dielectric body can be expanded. We provide completeness proofs, and also present results of numerical calculations that illustrate the relationship between the leaky modes and the resonances of dielectric cavities formed by a simple parallel-plate slab, a glass sphere, and a glass cylinder.

In the absence of external excitation, light trapped within a dielectric medium generally decays by leaking out, and also by getting absorbed within the medium. We analyze the leaky modes of solid dielectric spheres by examining solutions of Maxwell's equations for simple homogeneous, isotropic, linearly dispersive media that admit complex-valued oscillation frequencies. We show that, under appropriate circumstances, these leaky modes constitute a complete set into which an initial electromagnetic field distribution inside a dielectric sphere can be expanded. We provide the outline of a completeness proof, and also present results of numerical calculations that illustrate the close relationship between the leaky modes and the resonances of solid dielectric spherical cavities.

Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.

A evolução nos sistemas digitais de comunicação está intrinsicamente relacionada ao desenvolvimento da tecnologia de fibras ópticas. Desde a sua criação, na década de 60, inúmeras pesquisas vem sendo realizadas com o intuito de aumentar a capacidade de informação transmitida, por meio da redução da atenuação, controle da dispersão cromática e eliminação das não-linearidades. Neste contexto, as Fibras de Bragg surgem como uma estrutura de grande potencialidade para se minimizar tais inconvenientes. As fibras de Bragg possuem um mecanismo de operação diferente em relação às fibras tradicionais de suportar os modos confinados. Nelas, o núcleo possui um baixo índice de refração, e a casca é constituída por anéis dielétricos de diferentes índices de refração, alocados alternadamente. Para uma fibra de Bragg com núcleo oco, como a considerada neste trabalho, há perdas decorrentes dos modos de fuga. Portanto, a análise da dispersão destas estruturas se situa no plano complexo, tornando-a muito difícil. Esta dissertação será fundamentada em uma estratégia imprescindível à análise dos modos transversais TE0m, TM0m e dos híbridos. Os resultados encontrados são validados confrontando-os com os obtidos na literatura. O trabalho discutirá as perdas e dispersões dos modos citados, e os resultados obtidos poderão nortear as pesquisas das fibras de Bragg.<br>The evolution of digital communication systems is intrinsically related to the development of optical fiber technology. Since its creation in the 1960s, many studies have been conducted in order to increase the system capacity, such as the attenuation reduction, chromatic dispersion control and elimination of nonlinearities. In this context, Bragg fibers appear as a structure with great potential to mitigate these drawbacks. Bragg fibers have a different operational mechanism with respect to traditional fibers to support the confined modes. Their core has a low refractive index, and the cladding consists of dielectric rings of different refractive indices, allocated alternately. For a Bragg fiber with hollow core, as considered in this paper, there are losses due to the occurrence of leaky modes. Therefore, the dispersion analysis of these structures falls in the complex plane, making it even harder. This dissertation will be based on a strategy essential to the analysis of transverse modes: TE0m, TM0m and hybrids. The found results have been validated by comparing them with those obtained in the literature. The paper discusses the losses and dispersions of the mentioned modes, and the results obtained will serve to guide the research on Bragg fibers.

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 obtenue<br>Various 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

This thesis improves on the design of the leaky-mode spatial light modulator, LMW-SLM, presented by Dr. Smalley[1]. Improvements include: input coupling gratings, a pulsed laser input, output coupling gratings, and a 3D printed adjustable module for the stabilization of critical alignments. First, input coupling gratings reduce the cost of the LMW-SLM from $500 to around $2, a drop in cost of over two orders of magnitude. This enables multiple modulators to be used in a single display and allows for an inexpensive modular design to be created. Second, a pulsed laser input allows for image creation without the use of a polygon for derotation. Removal of the polygon allows for direct viewing of the LMW-SLM output enabling near-eye and flat panel displays. Third, output coupling gratings allow for bottom exit devices that are essential for thin substrates and flat panel displays. Fourth, the 3D printed module allows for the critical alignments of the LMW-SLM to become permanent. This in turns allows for transportation of the created displays without a trained technician by abstracting away the complexities of the device. The resulting changes simplify hardware, reduce cost, and enable the LMW-SLM to be modularized and the resulting 3D displays to be transportable. These improvements are made possible by the addition of a one new mask step during fabrication, a simple circuit design, and a 3D printed module designed in SOLIDWORKS. Included in this thesis as attachments are the MATLab, Eagle, and SOLIDWORKS files used to create the improved LMW-SLM.

Thesis (M.S.)--West Virginia University, 1999.<br>Title from document title page. Document formatted into pages; contains ix, 123 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 64-65).

This thesis deals with the development of a mathematical model for an air brake system in the presence of leaks. Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the US are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake defects such as leaks are a major cause of accidents involving trucks. Leaks in the air brake systems affect braking performance drastically by decreasing the peak braking pressures attained and also increasing the time required to attain the same, thereby resulting in longer stopping distances. Hence there is a need for detecting leaks in an air brake system. In this thesis, a mathematical model for an air brake system in the presence of leaks is developed with a view towards developing an automatic leak detection system in the near future. The model developed here builds on an earlier research at Texas A&M University in which a "fault free" model of an air brake system is developed, i.e., a mathematical model of an air brake system that predicts how the pressure in the brake chamber evolves as a function of the brake pedal input when there are no leaks in the air brake system.In order to develop a model for an air brake system in the presence of leaks, one must characterize a "leak". A leak may be characterized by the location and its size. Since the pipes are short, the location of the leak does not significantly affect the evolution in the brake pressure as much as its size. For this reason, "effective area" of the leak was chosen as a characteristic of the leak. It was estimated by fitting an empirical relation for leak with leak flow measurement data. The supply pressure and effective area of leak comprised the inputs to the model along with the displacement of the foot pedal (treadle valve plunger). The model was corroborated with the experimental data collected using the setup at Texas A&M University.

This thesis solves estimation and control problems in computational neuroscience, mathematically dealing with the first-passage times of diffusion stochastic processes. We first derive estimation algorithms for model parameters from first-passage time observations, and then we derive algorithms for the control of first-passage times. Finally, we solve an optimal design problem which combines elements of the first two: we ask how to elicit first-passage times such as to facilitate model estimation based on said first-passage observations. The main mathematical tools used are the Fokker-Planck partial differential equation for evolution of probability densities, the Hamilton-Jacobi-Bellman equation of optimal control and the adjoint optimization principle from optimal control theory. The focus is on developing computational schemes for the solution of the problems. The schemes are implemented and are tested for a wide range of parameters.

<p>An adaptive Luenberger-type observer with the purpose of locating and quantifying leakages is presented. The observer only needs measurements of velocity and temperature at the inlet and pressure at the outlet to function. The beneficial effect of output injection in form of boundary conditions is utilized to ensure fast convergence of the observer error. This approach is different from the usual practice where output injection might appear as a part of the PDE’s. This makes it possible to employ OLGA, which is a state of the art computational fluid dynamics simulator, to govern the one-phase fluid flow of the observer. Using OLGA as a base for the simulations introduces the possibility to incorporate temperature dynamics in the simulations which in previous work was impossible. The observer is tested with both a straight, horizontal pipeline and an actual, long pipeline with difference in altitude. Both simulations with oil and gas are carried out and verification of the robustness of the observer is emphasized. In order to cope with modelling errors and biased measurements, estimation of roughness in the monitored pipeline is introduced.</p>

Developing a robust pipe leak monitoring tool is essential as it continuously monitors pipeline health without disrupting normal operation. It is critical to understand the physical phenomena in the leakage area to develop a robust pipeline condition monitoring. This research project provides a better understanding of pipe leakage fluid dynamics and their influences on acoustic emission signal generation. The findings obtained from this project lay the groundwork for the development of a robust pipeline condition monitoring technique that could be implemented without disrupting normal operation. Such a monitoring tool would have significant financial, environmental, and social benefits.

Since the mid-1990s, formal verification has become increasingly important because it can provide guarantees that a software system is free of bugs and working correctly based on a provided model. Verification of biological and medical systems is a promising application of formal verification. Human neural networks have recently been emulated and studied as a biological system. Some recent research has been done on modelling some crucial neuronal circuits and using model checking techniques to verify their temporal properties. In large case studies, model checkers often cannot prove the given property at the desired level of generality. In this thesis, we provide a model using the Coq proof assistant and prove some properties concerning the dynamic behavior of some basic neuronal structures. Understanding the behavior of these modules is crucial because they constitute the elementary building blocks of bigger neuronal circuits. By using a proof assistant, we guarantee that the properties are true in the general case, that is, true for any input values, any length of input, and any amount of time. In this thesis, we define a model of human neural networks. We verify some properties of this model starting with properties of neurons. Neurons are the smallest unit in a human neuronal network. In the next step, we prove properties about functional structures of human neural networks which are called archetypes. Archetypes consist of two or more neurons connected in a suitable way. They are known for displaying some particular classes of behaviours, and their compositions govern several important functions such as walking, breathing, etc. The next step is verifying properties about structures that couple different archetypes to perform more complicated actions. We prove a property about one of these kinds of compositions. With such a model, there is the potential to detect inactive regions of the human brain and to treat mental disorders. Furthermore, our approach can be generalized to the verification of other kinds of networks, such as regulatory, metabolic, or environmental networks.

Film display holograms typically diffract light over a wide enough view-angle to be viewed, directly, without intervening optics. However, all holographic video displays must use optics beyond the hologram surface to overcome the challenges of small display extent and low diffraction angle by using some form of demagnification and derotation. We report a leaky mode waveguide spatial light modulator (SLM) with sufficiently high angular diffraction to obviate the need for demagnification in scanned aperture systems. This was achieved by performing a number of experiments to determine the depth of the annealed, proton-exchanged waveguide which corresponded to a maximized diffracted angle. Diffraction sweeps were recorded in excess of 19.5° for 632.8 nm light which is above the 15° required for direct view display. Moreover, we present a paired set of waveguide SLMs capable of a maximum light deflection nearing 28° for red. This deflection, which is several times larger than the angular sweep of current, state-of-the-art modulators, is made possible by the unilateral, near-collinear waveguide nature of the leaky mode interaction. The ability to double angular output in this way, which is either not possible or not practical in other SLMs, is possible in leaky mode devices, thanks to the absence of zero-order light and the lack of high-order outputs. This combined structure has angular deflection high enough to enable color holographic video monitors that do not require angular magnification. Furthermore, the low cost and high angular deflection of these devices may make it possible to make large arrays for flat-screen video holography. One improvement that could be made to the current setup would be to increase the device's diffraction efficiency. One highly influential factor of diffraction efficiency for a Bragg-regime surface acoustic wave (SAW) grating is the length of the interaction between the light and the grating. In this work, we have shown that guided light in a reverse proton exchanged (RPE) waveguide experiences less loss. This enables us to create longer devices which eventually results in devices with higher diffraction efficiency. We have also researched on LCoS SLMs and used them for two different applications: (a) photophoretic-trap volumetric displays and (b) holographic video displays. In the first case, aberrations including spherical, astigmatism, and coma can make particles to trap tighter in the focal point of the beam. Also, a new approach for holographic computations is presented which uses the electromagnetic nature of light in Maxwell Equations to find a unique phase map for every specific 3D object in space.

This is a thesis about The Eight Circuit Model, a modern mind map developed for the purpose of illumination and enlighenment by Dr. Timothy Leary in the 1970s. Later, authors such as Robert Anton Wilson and Antero Alli elaborated upon the idea to make it more wholesome and compatible with other ideas expressing the same basic principle. In short, it is an intellectual abstraction of the evolution of consciousness through a series of eight stages, which Leary called Circuits. By looking at the brain as an evolving bio-computer, with thoughts working as software, upgrading itself through neurological imprints, Learys created a Hero's Journey for the modern age.The thesis tries to analyze this idea, as it is presented in Robert Anton Wilsons Prometheus Rising, through the lens of the discourse category ”Western Esoterism.” A hard-to-define subject but described as ”the dialectic of the hidden and the revealed in the field of religion.”

A major limitation of acousto-optic (AO) leaky-mode modulator based holographic displays is their inability to present full-parallax. We propose that full-parallax capabilities can be bestowed on these displays by integrating an electro-optic (EO) phased array into the architecture. We validated this concept by rendering computational models and by fabricating and testing a basic two-axis AO/EO deflector prototype in lithium niobate. This was, to our knowledge, the first instantiation of an integrated, hybrid AO/EO deflector. The prototype had a 6° deflection range along the AO-axis, and a 3° deflection range along the EO-axis. A series of models provide us with a clear path forward for optimizing this deflector. They suggest that an AO/EO modulator with an EO deflection range of 24.5° and that requires less than 7.5 V can be fabricated within the limitations of standard photolithography.

In traditional investment decision making, one tool commonly used is the mean variance model, also known as an expected-value variance (EV) model, which evaluates the anticipated payout of different assets with respect to uncertainty where portfolios with higher risk demand higher expected returns from an individual. This thesis adapts this framework to a cost setting where decision makers are evaluating alternative physical assets that carry lifetime cost uncertainty for maintenance. Specifically, this paper examines homeowner choices for their home plumbing systems in the event of a pinhole leak, a tiny pin-sized hole that forms in copper, drinking-water pipes. These leaks can cause substantial damage and cost homeowners thousands of dollars in repairs. Since pinhole leaks are not related to the age of pipe material, a homeowner is subject to the risk of additional costs if a pinhole leak occurs again despite their repair efforts. The EV cost model in this paper defines two discrete choices for the homeowner in the event of a leak; to apply a simple repair at lower cost and higher future cost uncertainty, or to replace their plumbing with new pipe material, usually made of plastic, at a higher upfront cost but lower likelihood of future expenses. The risk preference of homeowners are demonstrated by their repair strategy selection, as well as the level of cost they incur to reduce uncertainty. Risk neutral individuals will select the repair strategy with the lowest lifetime expected cost and high variance, while risk averse homeowners will prefer to replace their plumbing with higher cost but lower variance. Risk averse individuals are also exposed to indirect costs, which is an additional unobserved cost in the form of a risk premium the homeowner is willing to pay to remove all uncertainty of future pinhole leak expense. Expected costs and variances are also higher for regions in the U.S. that experience elevated leak incident rates, known as hotspots. Using this mean variance cost framework, indirect cost can be quantified for homeowners in hotspot regions and compared to the rest of the U.S. to evaluate the magnitude of pinhole leak risk. The EV cost model estimates risk premiums on pinhole leaks to be $442 for homeowners in hotspots and $305 for those in the rest of the U.S. Finally, this paper examines the impact of pinhole leak cost uncertainty on the U.S. economy. Of an estimated $692 million in annual pinhole leak costs to homeowners, this study estimates a lower bound cost of $54 million per year (7.8% of estimated national annual cost) in risk premium that homeowners would be willing to pay to avoid pinhole leak cost uncertainty. Information in this study on the role of risk in home plumbing decisions and indirect costs would be helpful to policymakers and water utility managers as they deal with infrastructure management decisions. Furthermore, the EV cost methodology established in this paper demonstrates an effective use of mean variance modeling under cost uncertainty.<br>Master of Science

Orientador: Edevar Luvizotto Junior<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo<br>Made available in DSpace on 2018-08-05T06:54:25Z (GMT). No. of bitstreams: 1 Gumier_CarlosCesar_M.pdf: 3470729 bytes, checksum: 2e93f4938a5eb678d7fb52827439bbc5 (MD5) Previous issue date: 2005<br>Resumo: Este trabalho apresenta, sob diversos aspectos, as perdas de água que ocorrem nas redes de distribuição dos sistemas de abastecimento e os mecanismos de controle disponíveis. Dentre os objetivos se destaca a proposição do modelo matemático-computacional como uma nova ferramenta de localização de fugas. O modelo proposto foi desenvolvido através do acoplamento de um simulador hidráulico baseado no Time Marching Approach ¿ TMA com o algoritmo otimizador de Nelder-Mead. O trabalho visa ampliar os resultados obtidos nas investigações desenvolvidas em LUVIZOTTO (1998) e OCAMPOS (2003), aplicando o modelo em uma rede de distribuição de água real, utilizando os recursos disponibilizados pela companhia de água, propondo uma metodo de aplicação do modelo para tais condições<br>Abstract: This work presents, under diverse aspects, the water losses that occur in the distribution networks of the water supply systems and the available mechanisms of control. Amongst the objectives, it detaches the proposal of a computational model as a new tool for leak localization. The considered model was developed through the coupling of hydraulic simulator based in Time Marching Approach ¿ TMA method with the Nelder-Mead optimization algorithm. The work aims to extend the results obtained by LUVIZOTTO (1998) and OCAMPOS (2003), by applying the model to a real water distribution network, using the data provided by the water company and suggesting a methodology for application of the model for such conditions<br>Mestrado<br>Recursos Hidricos<br>Mestre em Engenharia Civil

The ubiquitous abundance of organic compounds in natural and anthorpogenically influenced eco-systems has put these compounds into the focus of atmospheric research. Organic compounds have an impact on air quality, climate, and human health. Moreover, they affect particle growth, secondary organic aerosol (SOA) formation, and the global radiation budget by altering particle properties. To investigate the multiphase chemistry of organic compounds and interactions with the aqueous phase in the troposphere, modelling can provide a useful tool. The oxidation of larger organic molecules to the final product CO2 can involve a huge number of intermediate compounds and tens of thousands of reactions. Therefore, the creation of explicit mechanisms relies on automated mechanism construction. Estimation methods for the prediction of the kinetic data needed to describe the degradation of these intermediates are inevitable due to the infeasibility of an experimental determination of all necessary data. Current aqueous phase descriptions of organic chemistry lag behind the gas phase descriptions in atmospheric chemical mechanisms despite its importance for the multiphase chemistry of organic compounds. In this dissertation, the gas phase mechanism Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) has been advanced by a protocol for the description of the oxidation of organic compounds in the aqueous phase. Therefore, a database with kinetic data of 465 aqueous phase hydroxyl radical and 129 aqueous phase nitrate radical reactions with organic compounds has been compiled and evaluated. The database was used to evaluate currently available estimation methods for the prediction of aqueous phase kinetic data of reactions of organic compounds. Among the investigated methods were correlations of gas and aqueous kinetic data, kinetic data of homologous series of various compound classes, reactivity comparisons of inorganic radical oxidants, Evans-Polanyi-type correlations, and structure-activity relationships (SARs). Evans-Polanyi-type correlations have been improved for the purpose of automated mechanism self-generation of mechanisms with large organic molecules. A protocol has been designed based on SARs for hydroxyl radical reactions and the improved Evans-Polanyi-type correlations for nitrate radical reactions with organic compounds. The protocol was assessed in a series of critical sensitivity studies, where uncertainties of critical parameters were investigated. The advanced multiphase generator GECKO-A was used to generate mechanisms, which were applied in box model studies and validated against two sets of aerosol chamber experiments. Experiments differed by the initial compounds used (hexane and trimethylbenzene) and the experimental conditions (UV-C lights off/on and additional in-situ hydroxyl radical source no/yes). Reasonable to good agreement of the modelled and experimental results was achieved in these studies. Finally, GECKO-A was used to create two new CAPRAM version, where, for the first time, branchingratios for different reaction pathways were introduced and the chemistry of compounds with up to four carbon atoms has been extended. The most detailed mechanism comprises 4174 compounds and 7145 processes. Detailed investigations were performed under real tropospheric conditions in urban and remote continental environments. Model results showed significant improvements, especially in regard to the formation of organic aerosol mass. Detailed investigations of concentration-time profiles and chemical fluxes refined the current knowledge of the multiphase processing of organic compounds in the troposphere, but also pointed at current limitations of the generator protocol, the mechanisms created, and current understanding of aqueous phase processes of organic compounds<br>Das zahlreiche Vorkommen organischer Verbindungen in natürlichen und anthropogen beeinflussten Ökosystemen hat diese Verbindungen in den Fokus der Atmosphärenforschung gerückt. Organische Verbindungen beeinträchtigen die Luftqualität, die menschliche Gesundheit und das Klima. Weiterhin werden Partikelwachstum und -eigenschaften, sekundäre organische Partikelbildung und dadurch der globale Strahlungshaushalt durch sie beeinflusst. Um die troposphärische Multiphasenchemie organischer Verbindungen und Wechselwirkungen mit der Flüssigphase zu untersuchen, sind Modellstudien hilfreich. Die Oxidation großer organischer Moleküle führt zu einer Vielzahl an Zwischenprodukten. Der Abbau erfolgt in unzähligen Reaktionen bis hin zum Endprodukt CO2. Bei der Entwicklung expliziter Mechanismen muss deshalb für diese Verbindungen auf computergestützte, automatisierte Methoden zurückgegriffen werden. Abschätzungsmethoden für die Vorhersage kinetischer Daten zur Beschreibung des Abbaus der Zwischenprodukte sind unabdingbar, da eine experimentelle Bestimmung aller benötigten Daten nicht realisierbar ist. Die derzeitige Beschreibung der Flüssigphasenchemie unterliegt deutlich den Beschreibungen der Gasphase in atmosphärischen Chemiemechanismen trotz deren Relevanz für die Multiphasenchemie. In dieser Arbeit wurde der Gasphasenmechanismusgenerator GECKO-A (“Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere”) um ein Protokoll zur Oxidation organischer Verbindungen in der Flüssigphase erweitert. Dazu wurde eine Datenbank mit kinetischen Daten von 465 Hydroxylradikal- und 129 Nitratradikalreaktionen mit organischen Verbindungen angelegt und evaluiert. Mit Hilfe der Datenbank wurden derzeitige Abschätzungsmethoden für die Vorhersage kinetischer Daten von Flüssigphasenreaktionen organischer Verbindungen evaluiert. Die untersuchten Methoden beinhalteten Korrelationen kinetischer Daten aus Gas- und Flüssigphase, homologer Reihen verschiedener Stoffklassen, Reaktivitätsvergleiche, Evans-Polanyi-Korrelationen und Struktur-Reaktivitätsbeziehungen. Für die Mechanismusgenerierung großer organischer Moleküle wurden die Evans-Polanyi-Korrelationen in dieser Arbeit weiterentwickelt. Es wurde ein Protokol für die Mechanismusgenerierung entwickelt, das auf Struktur-Reaktivitätsbeziehungen bei Reaktionen von organischen Verbindungen mit OH-Radikalen und auf den erweiterten Evans-Polanyi-Korrelationen bei NO3-Radikalreaktionen beruht. Das Protokoll wurde umfangreich in einer Reihe von Sensitivitätsstudien getestet, um Unsicherheiten kritischer Parameter abzuschätzen. Der erweiterte Multiphasengenerator GECKO-A wurde dazu verwendet, neue Mechanismen zu generieren, die in Boxmodellstudien gegen Aerosolkammerexperimente evaluiert wurden. Die Experimentreihen unterschieden sich sowohl in der betrachteten Ausgangssubstanz (Hexan und Trimethylbenzen) und dem Experimentaufbau (ohne oder mit UV-C-Photolyse und ohne oder mit zusätzlicher partikulärer Hydroxylradikalquelle). Bei den Experimenten konnte eine zufriedenstellende bis gute Übereinstimmung der experimentellen und Modellergebnisse erreicht werden. Weiterhin wurde GECKO-A verwendet, um zwei neue CAPRAM-Versionen mit bis zu 4174 Verbindungen und 7145 Prozessen zu generieren. Erstmals wurden Verzweigungsverhältnisse in CAPRAM eingeführt. Außerdem wurde die Chemie organischer Verbindungen mit bis zu vier Kohlenstoffatomen erweitert. Umfangreiche Untersuchungen unter realistischen troposphärischen Bedingungen in urbanen und ländlichen Gebieten haben deutliche Verbesserungen der erweiterten Mechanismen besonders in Bezug auf Massenzuwachs des organischen Aerosolanteils gezeigt. Das Verständnis der organischen Multiphasenchemie konnte durch detaillierte Untersuchungen zu den Konzentrations-Zeit-Profilen und chemischen Flüssen vertieft werden, aber auch gegenwärtige Limitierungen des Generators, der erzeugten Mechanismen und unseres Verständnisses für Flüssigphasenprozesse organischer Verbindungen aufgezeigt werden

Ein ausgewogenes Geschlechterverhältnis verbessert die Leistungsfähigkeit von Teams, das ökonomische Wachstum von Unternehmen und deren Innovationsfähigkeit (vgl. Europäische Kommission 2011a, S. 4f; vgl. auch Corkery & Taylor 2012, S. 9). Obwohl in vielen Organisationen und Unternehmen diese Fakten mittlerweile bekannt sind, ist das Potenzial eines ausgewogenen Frauen- und Männeranteils in mittleren und hohen Karrierestufen nach wie vor unzureichend erschlossen. So zeigen die Daten des Statistischen Bundesamtes für das Jahr 2014, dass in akademischen und wissenschaftlichen Karrierewegen der Anteil an Frauen in Positionen mit steigendem Qualifikationsniveau und Status kontinuierlich abnimmt, und dies trotz der heute stark angeglichenen Ausbildungsqualifizierung von Frauen und Männern. In den höchsten Ebenen im Wissenschaftsbereich sind nur noch wenige Frauen vertreten (vgl. Statistisches Bundesamt 2014b, S. 3). Differenzen im Karriereverlauf von Frauen und Männern finden sich also bis heute in der Wissenschaft. Doch was sind die Gründe für diesen Scherenverlauf der Karrierewege von Wissenschaftlerinnen und Wissenschaftlern in Deutschland? Die Gründe liegen in einem Zusammenspiel kleinerer Vor- und Nachteile im gesamten Umfeld der Geschlechter, wie Ulmi und Maurer (2005, S. 35) resümieren. Denn grundsätzlich belegen Studienergebnisse, dass Wissenschaftlerinnen und Wissenschaftler unter identischen Rahmenbedingungen gleich produktiv sind (vgl. Andresen, Oppen & Simon 1999, S. 24). Ein einzelner Faktor oder Zeitpunkt kann somit für die im Verlauf auseinanderklaffenden Karrieren von Wissenschaftlerinnen und Wissenschaftlern nicht herangezogen werden. Bisher finden sich in der einschlägigen Literatur nur wenige Studien, die bei der Analyse von Wissenschaftskarrieren das Zusammenwirken von institutionellen Rahmenbedingungen sowie die Subjektseite berücksichtigen, wenngleich dieser Kombination beider Perspektiven eine bedeutende Rolle zukommt (vgl. Andresen et al. 1999, S. 40; vgl. auch Döge & Behnke 2004). Zudem fokussieren vorhandene Untersuchungen weitestgehend auf den Karriereverlauf nach einer kindbedingten Erwerbungsunterbrechung (u. a. Bauer, T. 2000; Krimmer, Stallmann, Behr & Zimmer 2003; Brandt 2012). Die vorliegende Studie analysiert unter Berücksichtigung beider Perspektiven die karrierebeeinflussenden – meritokratischen, individuellen und strukturellen – Einflussfaktoren von Wissenschaftskarrieren am Beispiel der Leibniz-Gemeinschaft als erste nicht-universitäre Wissenschaftsorganisation in Deutschland, die im Jahr 2012 flexible Zielquoten für Frauen einführte (vgl. Leibniz-Gemeinschaft 2013a, S. 1). Gleichzeitig werden Geschlechterunterschiede in Bezug auf die Faktorengruppen bzw. im wissenschaftlichen Karriereverlauf herausgearbeitet. Mit Blick auf die bestehende Unterrepräsentation von Frauen in höheren wissenschaftlichen Führungsebenen sollen des Weiteren die Gründe für den geringen Frauenanteil in höheren Positionen im Wissenschaftsbereich und zudem die Nutzungs- und Akzeptanzmuster von egalitärem Elternzeit-Modell, familienorientiertem Arbeitsplatz und flexiblen Frauenquoten auf der Mikro-, Meso- und Makroebene als Maßnahmen für mehr Geschlechtergleichstellung im Wissenschaftsbereich analysiert werden. Zur Erforschung des Studienthemas werden quantitative und qualitative Erhebungsverfahren kombiniert. Denn erst durch das Zusammenspiel qualitativer und quantitativer Methoden erhält man ein verlässliches Gesamtbild des zu untersuchenden sozialen Gegenstandes (vgl. Diekmann 2009, S. 543). Während die Daten der Online-Befragung unter allen Beschäftigten der Leibniz-Gemeinschaft (Vollerhebung) die Basis für allgemeine Aussagen in Bezug auf Wissenschaftskarrieren in der Leibniz-Gemeinschaft liefern und gleichzeitig mit ihnen die aufgestellten Hypothesen überprüft werden, vertiefen die vier durchgeführten leitfadengestützten Interviews mit Leibniz-Wissenschaftlerinnen und ihren Partnern die quantitativen Daten und unterfüttern sie exemplarisch mit individuellen Aussagen zum Forschungsthema. Bei den meritokratischen Faktoren bestätigen die gewonnenen Daten statistisch signifikant die Annahme, dass eine hohe Publikationsproduktivität der stärkste Karrieremotor für eine Wissenschaftskarriere ist. Dies gilt einerseits für das Erreichen einer höheren Position sowie auch für den erfolgreichen Durchlauf der Qualifizierungsphasen von der Promotion bis hin zur Habilitation und Professur. Aber auch die Bedeutsamkeit von Auslandsaufenthalten und Mitgliedschaften in Fachgesellschaften als karrierefördernde Faktoren konnte bestätigt werden, wenngleich deren Einflussstärke hinter der von Publikationen zurückbleibt. Des Weiteren zeigt die Datenlage, dass die befragten Wissenschaftlerinnen nicht immer die gleichen Karrierechancen im Wissenschaftsbereich wie ihre männlichen Kollegen – trotz gleicher Leistungen und Erfahrungen – haben. So bleibt unter Kontrolle des Alters trotz gleicher Publikationsanzahl und Anzahl an Mitgliedschaften bei der erreichten Position ein signifikanter Unterschied zwischen den Geschlechtern zugunsten der Männer bestehen. Bei den strukturellen Faktoren haben sich die geschlechtsspezifische Fächerwahl (Fächergruppe), die Anzahl familienfreundlicher Unterstützungsmaßnahmen am Arbeitsplatz und die Akzeptanz von Frauenquoten in dieser Studie als Erklärungsvariable für den Scherenverlauf der Wissenschaftskarrieren der Geschlechter nicht bestätigt. Bei den individuellen Faktoren wird die Arbeitgeberorientierung (vgl. Vogt 2010) von Frauen und Männern ausgeschlossen. Ein individueller Faktor, der jedoch messbar einen Erklärungsanteil in dieser Studie einnimmt, ist der Faktor Kind bzw. das Vorhandensein von Kindern. Die Ergebnisse der Online-Befragung zeigen, dass in Bezug auf die Wissenschaftskarriere kinderlose Befragte erfolgreicher als Befragte mit Kind(ern) sind. Zudem gibt es Geschlechterunterschiede: Väter sind gegenüber Müttern hinsichtlich ihrer erreichten Position erfolgreicher. Folglich kann es nicht die Elternschaft per se sein, die eine Wissenschaftskarriere beeinflusst. Studien konnten einen direkt messbaren Einkommensnachteil für Frauen bzw. Karriereknick durch die (längere) Inanspruchnahme einer Elternzeit nachweisen (vgl. Ruhm 1998; vgl. auch Boll 2009; Busch 2013a; Brandt 2012), sodass die Ergebnisse zur Elternzeit als Einflussfaktor auf Wissenschaftskarrieren betrachtet werden müssen. In diesem Zusammenhang werden ebenso die Resultate zum egalitären Elternzeit-Modell als potenzielle Gleichstellungsmaßnahme bedeutsam. Insgesamt geht mit der Familiengründung ein gemeinsamer, aber langer Entscheidungsprozess für das Elternzeit-Modell (Verteilung der Elternzeitmonate zwischen den Partnern) in der Zweierbeziehung einher. Die Stärke der egalitären Einstellung, das Bildungsniveau oder der Karriereerfolg einer Person haben keinen Einfluss auf die Elternzeitdauer. Auch das Einkommen bestätigt sich durch die Daten nicht – im Kontrast zu vorhergehenden Studien (u. a. Hyde, Essex & Horton 1993; O’Brien 2009), die das Einkommen als Haupteinflussfaktor für die Inanspruchnahme der Elternzeit durch Väter belegen. In der vorliegenden Arbeit war den interviewten Männern eher die Unterstützung vom Vorgesetzten bzw. des Kollegenkreises zur Inanspruchnahme einer (längeren) Elternzeit wichtig. Die Unternehmenskultur ist somit eine Voraussetzung für die Wahl des Elternzeit-Modells. Besonders interessant bei den Ergebnissen der Online-Befragung zur Elternzeitdauer ist die über dem deutschen Durchschnitt (6 Monate in der Studie versus 3 Monate deutschlandweit; vgl. Fegert et al. 2011, S. 5) liegende Elternzeitdauer der Männer. Es verdeutlicht, dass auf der Mikroebene bei Vätern in der Leibniz-Gemeinschaft bereits modernere Geschlechterrollenorientierungen vorliegen. Auf der anderen Seite wurde durch die Datenlage bestätigt, dass eine längere Elternzeitdauer negativ mit der Karrierephase der befragten Männer korreliert (ein nachteiliger Karriereeffekt wurde auch in den Interviews mit den Vätern durch ihre persönlichen Erfahrungen bestätigt), während sie einen positiven Einfluss auf die Karrierephase bei Frauen hat. Als Erklärung kommt der Zeitpunkt der Familiengründung und folglich der Elternzeit infrage. Eine längere Elternzeit bei einer bereits fortgeschrittenen Karriere bei Frauen würde einen positiven Zusammenhang aufzeigen, während bei Männern der umgekehrte Fall vorliegen könnte. Es bleibt zu prüfen, ob weitere Untersuchungen die genannten Ergebnisse stützen können und ob sich ein egalitäres Elternzeit-Modell im Alltag durchsetzen kann, wenn Männer Karrierenachteile erfahren oder fürchten. Die tägliche Vereinbarkeit von Familie und Beruf ist für beide Geschlechter nicht einfach, sodass die befragten Frauen und Männer einige familienbedingte Spannungen am Arbeitsplatz verspüren. Ein familienorientierter Arbeitsplatz kann hier als Gleichstellungsmaßnahme auf der Mesoebene dazu beitragen beide Lebensbereiche zu vereinbaren: Die Daten belegen, dass Unterstützungsmaßnahmen zur Vereinbarkeit von Familie und Beruf signifikant die Anzahl an familienbedingten Spannungen am Arbeitsplatz reduzieren. Die Anzahl an Maßnahmen zur Unterstützung der Vereinbarkeit von Familie und Beruf ist dabei zwischen den Leibniz-Einrichtungen unterschiedlich, wobei Einrichtungen mit eher vielen Beschäftigten auch (eher) viele Unterstützungsmaßnahmen aufweisen. Der Großteil der Beschäftigten bei der Leibniz-Gemeinschaft ist über die in 2012 eingeführten flexiblen Frauenquoten uninformiert, welche als dritte Gleichstellungsmaßnahme in der Studie untersucht wurden. Weiterhin lehnen Männer die Einführung von Frauenquoten signifikant stärker ab als Frauen. Auf der anderen Seite wünschen sich stärker egalitär eingestellte Personen eher die Einführung von Frauenquoten als Maßnahme für mehr Chancengleichheit von Frauen und Männern im Wissenschaftsbereich als weniger egalitär eingestellte Personen. Werden Frauenquoten eingeführt, so wünschen sich die Befragten, dass diese ambitioniert, aber realistisch zu erreichen sind und mit einem entsprechenden Monitoring begleitet werden. Insgesamt besteht eine generelle Skepsis gegenüber Frauenquoten, wie in den Interviews und bei der Online-Befragung ersichtlich wird. Zur Erhöhung des Frauenanteils in wissenschaftlichen Führungspositionen wird durch die Daten belegt, dass eine Quotierung nur hilfreich ist, wenn „zugleich Führung und Verantwortung in Job und Familie miteinander vereinbar werden“ (vgl. Boll 2012, S. 650). Mit Blick auf die vorgestellten Studienergebnisse wird deutlich, dass Geschlechtergleichstellung in der Wissenschaft noch nicht erreicht ist. Damit Frauen in der Wissenschaft die gleichen Chancen wie Männer haben, müssen verschiedene Stellschrauben bewegt werden: Auf der Makroebene haben Frauenquoten das Potenzial die weibliche Repräsentanz zu erhöhen, um über paritätisch besetzte Auswahlgremien geschlechtergerechtere Auswahl- und Einstellungsverfahren anzustoßen, denn aufgrund einer weiblichen Unterrepräsentanz in diesen Gremien kann es zu einer Geschlechterverzerrung bei der Nachbesetzung kommen, wie van den Brink (2010) in ihrer Studie in den Niederlanden beweisen konnte. Auf der Mesoebene muss die Geschlechtergleichstellung im Wissenschaftsbereich durch familienpolitische Maßnahmen unterstützt werden. Es sind familienorientierte Arbeitsplätze für eine noch stärkere Vereinbarkeit von Familie und Beruf vonnöten, um einen gesellschaftlichen Verhaltenswandel auf der Makroebene herbeizuführen und um gleichzeitig auf der Mikroebene das innerfamiliäre Engagement beider Partner anzugleichen. Denn Gleichstellung muss auch privat gelebt werden, damit sie sich im Berufsalltag bzw. in unserer Gesellschaft durchsetzen kann.

Les défilés de mode mettent en scène des propositions visuelles sur les corps humains, habituellement ceux des mannequins minces. Dans le contexte contemporain, elles sont vantés comme des canons de beauté, mais d’autre part sont remises en question sur la réalité de leurs formes corporelles et la qualité de leur présence et de leur action sur les podiums: elles sont souvent vus comme des cintres de vêtements. Cependant sont eux qui conforment, avec les vêtements, des figures humaines, par des attitudes qui visent la composition des types de possibilités d’apparition. Notre étude se concentre dans le processus de ce mettre en forme, à travers de l’enquête sur les corps vêtus de défilés de mode, en utilisant comme exemples d'analyse quatre labels/créateurs brésiliens à la saison d'octobre 2016 de la São Paulo Fashion Week: Animale, Lab, Água de Coco et Ronaldo Fraga. Nous partons de la compréhension des visuels présentés dans des défilés de mode en tant que corps habillés, dans lesquels le corps et le vêtement travaillent ensemble pour la composition de la forme; et la capacité cinétique des corps et des vêtements, un élément qui dynamise les visuels. Cette activité réalisatrice des corps habillés dans les défilés de mode, leur action et mouvements corporels, sont de la compétence de leur dimension sensible, donc, en relation avec la culture et l'espace de manière intersubjective. Une telle réflexion nous invite à prendre en compte la relation des corps avec les types de défilés et ses éléments, tels que l'endroit, le son, les accessoires, toute l'atmosphère symbolique de la présentation, qui dirige les façons d'apparition des corps. Les corps habillés en défilés de mode se révèlent ainsi comme des formes complexes, sensibles et expressives des fuites corporelles<br>The fashion shows place to visuality dressing proposals on human bodies, generally those of the thin models. In the contemporary context, sometimes they are praised as canons of beauty, and at other times they are questioned about the reality of their corporal shapes and the quality of their presence and action on the runways: they are often seen as clothing hangers. But they are the ones who, allied to the clothes, conform human figures, in attitudes that aim the composition of possibilities of apparition. Our study investigates the process of this put in form, by examining the dressed bodies in fashion shows, using as examples for analysis the bodies in runways of four brazilian brands/designers of the October 2016 season of São Paulo Fashion Week: Animale, Lab, Água de Coco and Ronaldo Fraga. We start from the comprehension of the visuals presented in fashion shows as dressed bodies, in which body and clothes work together for the composition of the form in possibilities of combinations; and the kinetic capacity of body and clothing, an element that dynamizes the human visual. In this sense, we look for this realization of the dressed bodies in fashion shows through their action and their body movements, which are the competence of their sensitive dimension, related, therefore, with culture and space in an intersubjective way. Such a thought urges us to take into account, in this studied put in form, the relation of bodies with the types of fashion shows and with their elements, such as location, sound, props, the whole symbolic atmosphere of the elaborated presentation. The dressed bodies in fashion shows are thus revealed as complex, sensitive and expressive shapes and forms of body leaks<br>Os desfiles de moda colocam à visualidade propostas vestimentares sobre corpos humanos, geralmente os das modelos magras. No contexto contemporâneo, ora são elogiadas como cânones de beleza, ora questionadas quanto à realidade de suas formas corporais e à qualidade de sua presença e ação nas passarelas: são tidas, em muitos momentos, como cabides de roupas. Mas são elas que, aliadas às roupas, conformam figuras humanas, em atitudes que miram a composição de possibilidades de aparição. O nosso estudo se debruça sobre o processo desse por em forma, investigando os corpos vestidos de desfiles de moda, utilizando como exemplos para análise quatro marcas/designers brasileiros da edição de outubro de 2016 da São Paulo Fashion Week: Animale, Lab, Água de Coco e Ronaldo Fraga. Partimos da compreensão das visualidades apresentadas em desfiles de moda como corpos vestidos, em que corpo e roupa operam juntos para a composição da forma em possibilidades de combinações; e a capacidade cinética de corpo e roupa, elemento que dinamiza a visualidade. Nesse sentido, atentamos para essa realização dos corpos vestidos nos desfiles de moda por meio de sua ação e movimentos corporais, que são da competência de sua dimensão sensível, se relacionando, portanto, com a cultura e o espaço de maneira intersubjetiva. Tal fato nos instiga a ter em conta, no por em forma estudado, a relação dos corpos com os tipos de desfiles e seus elementos, como locação, som e adereços, toda a atmosfera simbólica da apresentação elaborada, que direciona as maneiras de aparição do corpo. Os corpos vestidos de desfiles de moda se desvelam, assim, como formas complexas, sensíveis e expressivas de vazamentos corporais

Les fuites internes jouent un rôle très important sur les performances des machines volumétriques, en particulier sur le débit réel à l'aspiration et le vide limite qu'il est possible d'atteindre. Pour les pompes volumétriques travaillant dans le vide grossier, les écoulements de fuites internes peuvent être convenablement décrits par un modèle de fluide visqueux. En revanche, dans le vide poussé, les écoulements de fuites internes doivent être décrits dans le cadre de la théorie cinétique des gaz. Entre ces deux régimes extrêmes d’écoulement, on a affaire au régime intermédiaire pour lequel il n'existe pas de formulation simple. Le but de notre travail est de dégager des modèles d’écoulement simples et réalistes, représentant les trois régimes susceptibles d’être rencontrés dans les machines volumétriques produisant des vides moyens. On trouve dans ce mémoire, la description de deux modèles semi-empiriques et celle d'une étude expérimentale. Cette dernière est conçue pour valider les modèles précédents. Elle fait intervenir des écoulements intermédiaires dans des jeux annulaires de dimensions équivalentes à celles des jeux de fuites dans les pompes à vide.

The "Mark V" Holographic Video Monitor ("HoloMonitor") is a continuation of effort and accomplishments to produce a low-cost device capable of reproducing true full-color horizontal-parallax-only computer-generated holograms at typical video frame-rates. While other devices around the world may have greater capabilities, these devices are currently confined to laboratory settings due to their sheer complexity and expense. The aim of this project is to provide researchers and "tinkerers" with a device capable of recreating holographic effects in full color, respectable resolution, in real time, and at a comparatively low cost. The "Mark V" HoloMonitor is a closer representation of a consumer product than any other device of the MIT/BYU series of HoloMonitors. In this thesis, I discuss the complete design and construction of all of the optic (sans modulator) electronic subsystems that compose this device, along with explaining and providing working code needed to drive it in various modes of operation. The main objective of this thesis is to sufficiently instruct undergraduate and graduate colleagues so that they can replicate and build upon this work.

One of the most powerful and important applications that the brain accomplishes is solving the sensory "cocktail party problem:" to adaptively suppress extraneous signals in an environment. Theoretical studies suggest that the solution to the problem involves an adaptive filter, which learns to remove the redundant noise. However, neural learning is also in its infancy and there are still many questions about the stability and application of synaptic learning rules for neural computation. In this thesis, the implementation of an adaptive filter in the brain of a weakly electric fish, A. Leptorhynchus, was studied. It was found to require a cerebellar architecture that could supply independent frequency channels of delayed feedback and multiple burst learning rules that could shape this feedback. This unifies two ideas about the function of the cerebellum that were previously separate: the cerebellum as an adaptive filter and as a generator of precise temporal inputs.

Early administration of broad-spectrum antibiotics is the first goal in sepsis treatment. Besides from bacteriostatic/bactericidal effects, some antibiotics may also modify the host´s response to infection. The novel antibiotic tigecycline may exert such properties; however, this property has not been evaluated in large-animal trials. We compared tigecycline with doxycycline and placebo in relation to anti-inflammatory, circulatory and organ dysfunction effects in a sterile pig model of sepsis. Doxycycline, but not tigecycline, reduced the inflammatory response as manifested by tumor necrosis factor alpha levels in plasma. Tigecycline, however, had a stabilizing effect on the circulation not exerted by doxycycline or placebo. To achieve rapid restoration of the circulating blood volume - another major goal in sepsis treatment - fluid bolus administration of is some-times practiced. In addition to crystalloids, albumin-containing solutions are suggested. Yet, some animal-experimental data suggests that rapid bolus administration of albumin reduces albumin’s plasma-expanding effect. We compared a rapid intravenous bolus of radiolabeled albumin with a slow infusion in a sterile pig model of sepsis. Rapid bolus of administration did not reduce plasma levels of albumin following administration and did not increase the amount of albumin that left the circulation. Inadequate oxygen delivery (DO2) by the circulation to the tissues may cause increased plasma lactate, which is the most striking effect of sepsis on the metabolism. However, experimental data and clinical trials refute this link, instead, suggesting other mechanisms, including impaired oxygen extraction, mitochondrial dysfunction and accelerated aerobic glycolysis. We investigated the impact of DO2, oxygen consumption (VO2), hemodynamic parameters and inflammatory response on plasma lactate and organ dysfunction in two experimental sepsis models. In the most severe cases of shock, with DO2, there was an increase in plasma lactate, but without a decrease in VO2, invalidating the assumption that the increase in lactate is due to anaerobic metabolism. To identify critical steps in the sepsis-induced increase in lactate, we inhibited the major energy-producing step in the electron transport chain (ETC). The combination of sepsis and ETC inhibition led to a cellular energy crisis. This finding suggests that early sepsis induces a partial mitochondrial dysfunction.

La logistique urbaine, et celle du dernier kilomètre notamment, est un sujet de préoccupation majeure pour les villes d’aujourd’hui. Pour répondre à cette préoccupation, nous avons établi dans le chapitre introductif un historique de la problématique de la logistique urbaine pour mieux comprendre son développement au fil des années, permettant ainsi de déduire qu’il est fondamental d’étudier la globalité de la chaîne de distribution dans ce travail de thèse pour mieux résoudre la problématique de la logistique urbaine. En revanche, nous étions confrontés à un sujet redoutable par sa complexité et l’absence de données complètes et fiables. De plus, nous assistons dans les dernières années, à une multiplication des schémas logistiques que ce soit pour la livraison des magasins à partir des entrepôts des fournisseurs ou pour l’approvisionnement des clients à partir des surfaces de vente.De ce fait, nous avons fixé comme objectif d’identifier toutes les organisations logistiques existantes et émergentes en France et ailleurs (deux séjours d’un an en Angleterre et en Suisse). Pour ce faire, nous avons déterminé dans le deuxième chapitre les paramètres de différenciation des modes d’organisation en amont (de l’entrepôt du fournisseur à la surface de vente) et en aval de la chaîne (de la surface de vente au domicile du client). Or il n’existe pas aujourd’hui de bilan économique et environnemental complet permettant d’arbitrer entre différentes formes de distribution classiques et à distance en tenant compte des particularités des familles des produits (non alimentaires, secs, frais, surgelés) et de la diversité de leurs modes de livraison.Face à ces contraintes de taille, nous avons eu recours aux enquêtes de terrain dans ce travail de recherche, qui ont été l’occasion de nouer de très nombreux contacts avec les acteurs de la grande distribution, permettant ainsi de recueillir des données techniques et économiques de première main et inédites jusqu’ici. En plus de la résolution du verrou empirique dans le troisième chapitre, ce travail de thèse a permis également de lever des verrous méthodologiques relatifs à la reconstitution et à l’évaluation des coûts et des émissions logistiques (pour les entrepôts de stockage et les plateformes de transit en amont ; et pour les surfaces de vente et les plateforme de mutualisation en aval) et des coûts et des émissions des véhicules de transport (des articulés et des porteurs en amont ; et des VUL, voitures particulières, transports publics, deux roues, et marche à pied en aval). Enfin, ce travail de thèse a permis d’aboutir à la construction d’une base de données et la mise au point d’un outil d’aide à la décision permettant ainsi de déduire, dans le quatrième chapitre, les bilans économique et environnemental de la globalité de la chaîne depuis l’entrepôt du fournisseur jusqu’au domicile du ménage. Cet outil devrait se révéler très utile pour les politiques publiques, les stratégies futures des grands distributeurs et leurs prestataires logistiques afin de privilégier les modes d’organisation économes et durables, et même pour le client final afin d’estimer les coûts et les émissions de ses actes d’achat dans les différentes alternatives de vente classique et à distance<br>Urban logistics and the last mile in particular, is a major concern for cities today. To address this concern, we have established in the introductory chapter a history of the problem of urban logistics. This allows a better understanding of its development over the years, and deducing that it’s essential to study the supply chain in its entirety to better solve the problem of urban logistics. However, we were faced with a daunting task: the lack of comprehensive and reliable data. In addition, there has been a multiplication of distribution channels in recent years. This includes the delivery from warehouses to stores and further to households from the retail space.Therefore, we intended to identify all existing and emerging logistics organizations in France and beyond (one year exchange stay in England and Switzerland for research purposes). To do this, we established in the second chapter certain parameters that differentiate the logistics modes of various organizations upstream (from manufacturers to retail stores) and downstream (from retail stores to households). Unfortunately, there does not exist any economic and environmental assessment to settle between different forms of traditional and modern electronic distribution, by taking into account the various characteristics of different products families (non-food, dry, fresh, frozen) and the diversity of their delivery modes.Faced with constraints of such size, we conducted surveys with different actors of distribution channels, which provided the opportunity to make contacts, thus collect firsthand and so far unpublished technical and economic data. In addition to the resolution of empirical inadequacy in the third chapter, this research also helped to develop a methodological approach related to the reconstruction and evaluation of logistics costs and emissions (in warehouses, transit platforms, retail stores and shared platforms) and also the costs and emissions of vehicles (trucks, delivery van, cars, public transport, bikes, motorbikes and walking).Finally, this research has lead to the construction of a database and the development of a decision support tool to infer, in the fourth chapter, the economic and environmental appraisal of the entire supply chain from the supplier's warehouse to the final customer. This tool can be useful for public policy, future strategies of retailers and Third-Party Logistics providers to focus on efficient and sustainable modes of organization, and even it will benefit the customer to estimate the costs and emissions of its acts of purchase in classic and e-grocery shopping

Les gastroentérites aiguës affectent chaque année entre un quart et la moitié des personnes dans le Monde. Elles sont causes de morbidité, de mortalité et de coûts de santé importants. Leur transmission directe ou indirecte via l’eau, les aliments, l’air ou les surfaces inertes dépend de leur étiologie (virale, bactérienne ou parasitaire) et du contexte local. Bogotá et sa région présentent plusieurs spécificités : des eaux usées rejetées en rivière souvent sans ou après seulement un traitement primaire, la mise en décharge des papiers toilettes, couches et protections souillés par les excréments, et une consommation de fruits et légumes faible et limitée à des produits bon marché irrigués par des eaux pouvant être contaminées fécalement. Notre thèse visait à évaluer les flux de certains pathogènes entériques de l’Homme dans l’environnement à proximité de Bogotá et à essayer de relier ces flux à la santé de la population.La thèse a associé trois contributions. Premièrement, une méthode de culture du norovirus humain a été mise au point en utilisant des villosités intestinales isolées de souris comme modèle cellulaire présentant toute la diversité des cellules épithéliales intestinales. Plusieurs concentrations en trypsine ont été testées pour activer les norovirus ; la méthode a été appliquée à des échantillons fécaux et environnementaux. Deuxièmement, les contaminations en E. coli et en pathogènes entériques de l’Homme ont été suivies dans des eaux (lixiviat de décharge, eau de ruissellement, rivière, eau d’irrigation, eau potable), des légumes-feuilles mangés crus (blettes) et l'air (au-dessus d’une décharge, en zone rurale, en zone urbaine) dans la région de Bogotá. Troisièmement, l’impact des contextes socioéconomiques et des pratiques individuelles (alimentation, hygiène et santé) sur les cas de gastroentérites aiguës a été testé à partir d’enquêtes réalisées dans un district de Bogotá et analysées par divers outils (analyse en composante principale, modélisation …).Nous avons montré que les villosités intestinales isolées de souris permettent l'infection et la réplication du norovirus humain. Le virus doit être activé avec de la trypsine et a un cycle réplicatif moyen de 10 h. Les villosités sont efficaces pour obtenir un matériel biologique abondant et sont idéales pour étudier l'activité biologique du norovirus ou générer des anticorps. Elles ont permis de voir des norovirus non détectés par méthode moléculaire dans certains excréments ou échantillons environnementaux ; les échantillons positifs par méthode moléculaire ou en immunodot-blot contenaient quasiment tous des norovirus infectieux. Au niveau régional, les rejets d'eaux usées dans les rivières Bogotá et Balsillas et dans le marais Tres Esquinas contaminent le réseau d'irrigation de La Ramada au nord-ouest de Bogotá en E. coli et potentiellement en pathogènes entériques de l’Homme. Les blettes récoltées dans cette zone étaient fortement contaminées, en contraste d’autres zones de culture. Leur contamination évoluait de leur production à leur achat dans les commerces de proximité, les lavages pouvant être contaminants ou décontaminants, les manipulations sur l’étal des marchands étant contaminantes. L’air était souvent contaminé par E. coli et par Shigella spp., sans pouvoir attribuer à la décharge Doña Juana un rôle particulier. La présence de Shigella spp. était observée parallèlement dans plus de la moitié des selles des personnes diarrhéiques. Les enquêtes réalisées ont montré que la fréquence annuelle des gastroentérites aiguës diminuait avec l’accroissement de l’âge des personnes ; elle semblait plus faible dans les foyers avec personnes âgées, peut-être en lien avec des pratiques plus strictes en matière d’hygiène, alimentaire notamment<br>Acute gastroenteritis affect between a quarter and a half of people in the World each year. They are responsible for significant morbidity, mortality and healthcare costs. Their direct or indirect transmissions via water, food, air or inert surfaces depend on their aetiology (viral, bacterial or parasitic) and the local context. Bogotá and its region have several specificities: wastewater are often discharged into rivers without or after primary treatment only, the deposit in landfill of toilet papers and diapers soiled by excrement, and the low consumption of fruits and vegetables largely restricted to a handful of relatively cheap products that may be irrigated by surface freshwaters heavily contaminated with faeces. Our PhD aimed to assess the fluxes of some human enteric pathogens in the region of Bogotá and to try to relate these fluxes to the population health. The PhD combined three contributions. First, a method for culturing the human norovirus has been developed using isolated mouse intestinal villi as a cell model exhibiting the full diversity of intestinal epithelial cells. Several concentrations of trypsin were tested to activate noroviruses; the method was applied to faecal and environmental samples. Second, contamination with E. coli and some human enteric pathogens was monitored in water (landfill leachate, runoff water, river, irrigation water, drinking water), leafy vegetables eaten raw (chards) and air (above a landfill, in rural areas, in urban areas) in the Bogotá region. Third, the impact of socioeconomic contexts and individual practices (food, hygiene and health) on cases of acute gastroenteritis was assessed from surveys carried out in one district of Bogotá and analysed by various tools (principal component analysis, modelling …). We have shown that mouse isolated intestinal villi allow the infection and replication of human norovirus. The virus has to be activated with trypsin and has an average replicative cycle of 10 h. Villi are efficient in obtaining abundant biological material and are ideal for studying the biological activity of norovirus or for generating antibodies. They made it possible to see infectious noroviruses not detected by molecular method in several faeces and environmental samples; almost all samples positive by molecular method or immunodot-blot contain infectious noroviruses. At the regional level, the discharges of wastewater in the Bogotá and Balsillas rivers and in Tres Esquinas march contaminate the irrigation network of La Ramada area in the northwest of Bogotá with E. coli and potentially human enteric pathogens. Chards harvested in this area were heavily contaminated, in contrast to other growing areas. Their contamination evolved from their production to their purchase in nearby stores, washings increasing or decreasing their contamination, and handling on the merchant's stalls increasing contamination. The air was often contaminated with E. coli and Shigella spp.; it was not possible to detect a particular contribution of the Doña Juana landfill in pathogen aerosolization. The presence of Shigella spp. was observed in parallel in more than half of the stools of people with diarrhoea. Surveys have shown that the annual frequency of acute gastroenteritis decreases with increasing age; it seemed less common in households with elderly people, possibly due to stricter food hygiene practices. A transmission model of acute gastroenteritis distinguishing contamination from outside the households and contaminations between people in the same households did not show significant differences between neighbourhoods. Used to simulate numerical experiments, it suggests working on much higher numbers of surveys<br>La gastroenteritis aguda afecta entre una cuarta parte y la mitad de las personas en el mundo cada año. Son responsables de importantes costos de morbilidad, mortalidad y asistencia sanitaria. Sus transmisiones directas o indirectas a través del agua, alimentos, aire o superficies inertes dependen de su etiología (viral, bacteriana o parasitaria) y del contexto local. Bogotá y su región aledaña tienen varias especificidades: las aguas residuales a menudo se vierten a los ríos sin o solo después de un tratamiento primario, el depósito de papel higiénico y pañales sucios con excrementos son dispuestos generalmente en un relleno sanitario, y el bajo consumo de frutas y verduras restringido en gran medida a un puñado de productos relativamente baratos pueden ser irrigados por aguas dulces superficiales muy contaminadas con excrementos. Nuestra tesis doctoral tuvo como objetivo evaluar los flujos de algunos patógenos entéricos humanos en la región de Bogotá y tratar de relacionar estos flujos con la salud de la población. El doctorado combinó tres contribuciones. En primer lugar, se desarrolló un método para cultivar el norovirus humano utilizando vellosidades intestinales aisladas de ratón como modelo celular que exhibe la diversidad completa de células epiteliales intestinales. Se probaron varias concentraciones de tripsina para activar norovirus; el método se aplicó a muestras fecales y ambientales. En segundo lugar, se evidenció la contaminación de E. coli y patógenos entéricos humanos en el agua (lixiviados de vertedero, agua de escorrentía, río, agua de riego, agua potable), vegetales de hoja que se comen crudos (acelgas) y aire (sobre un vertedero sanitario, así como en áreas rurales y urbanas) en la región de Bogotá. En tercer lugar, se evaluó el impacto de los contextos socioeconómicos y las prácticas individuales (alimentación, higiene y salud) frente a los casos de gastroenteritis aguda a partir de encuestas realizadas en una localidad de Bogotá y analizadas mediante diversas herramientas (análisis de componentes principales, modelización…). Con este doctorado, hemos demostrado que las vellosidades intestinales aisladas de ratón permiten la infección y la replicación del norovirus humano. El virus debe activarse con tripsina y tiene un ciclo replicativo promedio de 10 h. Las vellosidades son eficaces para obtener abundante material biológico y son ideales para estudiar la actividad biológica de los norovirus o para generar anticuerpos. Ellas permitieron ver norovirus infecciosos no detectados por método molecular en varias heces y muestras ambientales; casi todas las muestras positivas por método molecular o inmunodot-blot contienían norovirus infecciosos. A nivel regional, los vertidos de aguas residuales en los ríos Bogotá y Balsillas y en el humedal Tres Esquinas contaminan la red de riego La Ramada en el noroeste de Bogotá con E. coli y potencialmete con patógenos entéricos humanos. Las acelgas recolectadas en esta área resultaron muy contaminadas, a diferencia de otras áreas de cultivo. Su contaminación evolucionó desde la producción hasta su compra en las tiendas cercanas, los lavados aumentaron o disminuyeron su contaminación y la manipulación en los puestos de comercio aumentaron la contaminación. El aire a menudo estaba contaminado con E. coli y Shigella spp., sin poder atribuir al relleno sanitario Doña Juana un rol particular. A su vez la presencia de Shigella spp. se observó en paralelo en más de la mitad de las deposiciones de personas con diarrea. Las encuestas demostraron que la frecuencia anual de gastroenteritis aguda disminuye respecto al aumento en edad; parecía menos común en hogares con personas mayores, posiblemente debido a prácticas de higiene alimentaria más estrictas. Un modelo de transmisión de gastroenteritis aguda que distinguió la contaminación fuera de los hogares y las contaminaciones entre personas dentro de los mismos hogares no mostró diferencias significativas entre vecindarios

博士<br>國立交通大學<br>電子工程系<br>87<br>This thesis investigates the properties and applications of the first two higher order leaky modes of the microstrip, which include efficient feeding structures, mutual coupling on microstrips, coupling effect in different leaky modes, and several antenna applications. The spectral domain analysis is employed to solve the propagation characteristics of the microstrip leaky modes throughout this study. The first part of the thesis pertains to the first higher order leaky mode (odd mode) of the microstrip line. The design procedure of the microstrip first higher order leaky-mode antenna excited by aperture-coupling method is presented. Separating the radiators from other components with the ground planes provides optimal design of both parts respectively so that the inherent broadband, high gain and frequency-scanning properties of the leaky-wave antenna can be exploited. Tilted- and broadside-beam antennas are designed in X-band. Single and dual beams arrays in K-band and a base-station antenna application for S-band are also implemented. The required elements were reduced markedly in comparison with the patch antenna for higher gain design. Versatile designs combining the merits of multilayer technology offer simplicity and efficient design for many wireless applications. In addition, the coupling effects in the coupled microstrips, which caused by the first higher order leaky mode on the microstrip, are investigated. The resonance phenomena found between the strip of the infinite coupled microstrips are owing to the inner edges of the coupled microstrips forming the resonant boundary and the leaky modes of the microstrips serving as the resonant sources. For even- and odd-symmetry of the coupled microstrips, more than one leaky mode are found in both cases, and these leaky modes couple with each other. The second part of the thesis treats the subjects of the microstrip second higher order leaky mode (even mode). Mode-coupling phenomena of the even modes on microstrip is investigated. These phenomena occur when the dispersion curve of the leaky dominant mode of the microstrip is close to those of the even higher order modes of the microstrip. Interesting patterns of the migration of mode evolution, obtained by varying the ratio of the strip width to the substrate thickness, exhibit the relationships between the even higher order modes and the leaky dominant mode. The spectral gap effect of the even higher order modes is the result of the coupling between these modes and the leaky dominant mode. Design of the even higher order leaky mode as a line source should be based on the physical implications of these phenomena. Short-end CPW and microstrip feeding method are used to excite the second higher order leaky mode. Experimentally exciting the second higher order leaky mode with and without the leaky dominant mode reveals the interference between these two leaky modes.

博士<br>國立交通大學<br>電子研究所<br>83<br>The dyadic Green''s imprdance functions of gyromagnetic planar transmission lines are systemmatically established models. Full- wave numerical analyses are performed by appling the Galerkin''s method. After performing a series of numerical experiment, we conclude that the formation of the complex modes on the shielded gyromagnetic slotline is the result of coupling effects, caused by the presences of covers, among the leaky modes. A pair of dominant complex modes is formed on the reciprocal gyromagnetic coupled microstrips. By properly tunning the strip widths, a bandpass spectrum can be formed for such a guided wave structure and the passband was shown to be magnetically tunable. The same inhomogeneous stripline, the conventional dominant stripline mode becomes leaky and a parallel-plate-like dominant bound mode coexists with it. However, the dominant-mode leakage of gyromagnetic stripline can be suppresed by properly choosing the magnetic bias condition and operating frequency. A leaky-wave antenna operated with the first higher-order leaky mode of the gyromagnetic microstrip line is proposed and analyzed. It was shown that the beam angle of such a leaky-wave antenna can be steeered from horizopn to nearly vertical by only varing 6.5% of the DC magnetic bias field Ho.

碩士<br>國立交通大學<br>電信研究所<br>85<br>The leaky dominant modes on multiple coupled microstrips are investigated by the full-wave spectral domain approach (SDA) with appropriate deformation of integration contours to include the surface-wave poles. These modes exist independently of the customary bound dominant mode. They leak power away fromthe lines into the fundamental TM0 surface wave of the surrounding grounded substrate and may be responsible for spurious microstrip circuit performance at higher frequencies.

博士<br>國立交通大學<br>電信研究所<br>85<br>This thesis consists of two parts. The first part presents a novel electromagnetic simulation technique that incorporates a full-wave space-domain integral equation technique with a proposed excitation model based on the equivalence principle. The integral equation is solved numerically by Galerkin''s procedure resulting in the generalized scattering matrix (GSM) descriptions of the microwave circuit de-embedding. Rigorous convergence studies and extensive validity checks confirm the reliability and accuracy of the proposed method. The novel technique immediately demonstrates its obvious application for quantitative near-discontinuity characterization of higher-order modes and multimode associated with microwave circuit discontinuity problems. The newly proposed method is employed further to investigate the mode conversion of a CBCPW open-end discontinuity with unequal side plane widths. The conversion into two additional dominant modes, the c-mode-like mode and the ?mode-like mode, and into the transmitted microstrip mode from an incident CPW mode is studied against side plane width, degree of asymmetry, substrate thickness, and frequency. Theoretical results are in excellent agreement with experimental ones. The mode conversion associated with the surface-wave- like mode at discontinuities of CPW is also investigated. When incorporated with the segmentation method to analyze a complex and large microwave planar circuit, the novel technique analyzes individually each smaller segment and then combines them to yield overall network characterization of the composite circuit. This can significantly reduce the requirement of computation time and memory space. Very good agreement is obtained in a comparative study of an arbitrary planar structure analyzed by the full-wave method with and without segmentation, respectively. The second part of the thesis uses a rigorous full-wave mode-matching method, considering finite metal-strip thickness and conductivity, to investigate the leaky dominant modes on symmetric coupled microstrips with and without superstrate and on a finite-width conductor-backed CPW. This work demonstrates the significant effects of the top cover over these structures and proves that the even leaky dominant mode is an additional parallel-plate mode perturbed by the presence of the strips, which is different from the phenomenon that the odd leaky dominant mode is a conversion or evolution from the odd bound dominant mode. Moreover, a HEMT-based amplifier integrated with an arched microstrip line is developed for an oscillator-type active antenna. The microstrip line serves as a feedback circuit of the oscillator as well as a radiating element. Two microstrip-slotline transitions are used for interconnecting the amplifier and the leaky-wave antenna feedback loop, and thus no DC blocking capacitor is required. The far-field patterns of the arched antenna and the circuit performance including the self-mixing feature of the active antenna are presented.

碩士<br>國立清華大學<br>電子工程研究所<br>87<br>Discussed are the light transmission and their characteristics in a leaky step-index planar waveguide. In this waveguiding structure, an input guided mode will couple to continuous radiation modes, located in the leaky section. The major contribution of this thesis is to introduce a new concept - the leaky bound mode - to analyze the previous problem. The methodology is as follows. We are visionally incident a light ray from one side of the cladding to the leaky waveguide. If we can obtain extreme reflection, this condition corresponds to a new kind of bound modes, namely the leaky bound mode. This new method is straightforward and simple. Knowing the familiar light transmission and reflection by a multilayered structure are sufficient while this new method is actually originated from the evanescent field excitation, proposed by our predecessors. In this thesis, we also investigate the light throughput in leaky waveguides. Two methods based on the leaky bound mode and a ray-optic approach are presented and compared. Excellent agreement between the two methods is found. Our method is very useful and efficient in analyzing multilayered structures and no numerical technique, e.g., finite element method, is required.

博士<br>國立交通大學<br>電信工程研究所<br>84<br>A generic microstrip leaky-mode antenna is present. It consists of microstrip line on one side of substrate and uniplanar circuit on the other side. The leakage is producedby the excitation of the first higher-order (odd) microstrip mode coupledelectromagnetically through slotline on the opposite side of substrate. This feed designis uniplanar, which does not require via-holes and is easy to interface with active circuits. When the microstrip leaky-mode antenna placed in partially opened waveguide, itis a quasi-planar guiding structure. Theoretic results based on rigorous Green''simpedance integral equation method show that this new quasi-planar leaky- waveantenna has broadband tuning range via structure parameters, and is insensitive tomicrostrip line width variation. Measured relative power absorbed (RPA) resultsindicate that the useful frequency bandwidth agrees with what rigorous field theorypredicts. The measured antenna radiation patterns also agree very well withapproximate theoretic computations. A basic research carried out to design a microwave source module employing theconcept of an active integrated leaky-mode antenna. The novel active antenna sourcemodule utilizes microstrip as the radiating element while adopting uniplanartechnology for the active circuit design. The measured performance of an X-bandtransmission type injection-locked active integrated antenna source moduledemonstrated that such design approach was suitable for linear array integration forquasi-optical power combining. The harmonic balance (HB) analysis of the proposedactive integrated antenna agrees with the measurement in both free-running frequencyand power level. The measured radiation patterns of the active integrated antenna alsoagree well with the theoretical predictions.

碩士<br>國立交通大學<br>電信研究所<br>85<br>In this thesis, a HEMT-based differential amplifier integrated with a shortmicrostrip line is present for an self-oscillating active leaky-mode antenna.First, a differential feed short leaky-mode antenna with dual-beam radiationpattern is designed. This four-port element ( differential inputs and outputs)can be used in the active antenna as a radiating element. Secondly, weemploy a microstrip leaky-mode antenna and a feedback oscillator to design anoscillator type active antenna. The short microstrip line serves as a feedback network of the oscillator as well as a radiating element. Two highimpedance microstrip lines are used for interconnecting the differentialamplifier and the leaky-mode antenna feedback loop. The self-oscillating active antenna has been developed at 11.8 GHz and 10.74 dBm output power.Finally, we present a nonlinear transmission line (NLTL) used in the circuitas a phase-controlling element to tune the oscillation frequency with tuningbandwidth about 300 MHz.

博士<br>國立臺灣大學<br>電信工程學研究所<br>102<br>This dissertation presents a proximity-coupled microstrip EH1 mode array, a dual EH1 mode half-width microstrip antenna, and a differentially excited coupled half-width microstrip leaky EH1 mode antenna. In the design of the proximity-coupled microstrip EH1 mode array, the radiation characteristics of the EH1 mode microstrip line with a length shorter than one free space wavelength are investigated and designed as an array element. The matched radiating-element load is also proposed to provide the wider bandwidth of input impedance matching and the back lobe suppression. Furthermore, the equivalent transmission line model of array element is reported to predict the radiation efficiency of the array. The measured results of the antenna gain and the radiation efficiency are 19.1 dBi and 87% at 10.525 GHz, and the measured maximum radiation efficiency is 91% at 10.325 GHz. In the studies of dual EH1 mode half-width microstrip antenna design, the guided-wave structure support dual EH1 mode is proposed. A prototype design of dual EH1 mode antenna is also provided. The proposed guided-wave structure consists of two different half-width microstrip lines. Each half-width microstrip line supports an EH1 mode. The operation frequency of these two leaky modes can be designed independently. The isolation of two leaky modes is better than 20 dB over both leaky modes operation bands in simulated and measured results. Finally, a differentially excited coupled half-width microstrip leaky EH1 mode antenna is presented. The guided-wave structure of coupled half-width microstrip lines are proposed and investigated, showing two leaky modes in the form of even- and odd-symmetry, respectively. Rigorous studies show that the odd-leaky-mode iv outperforms the even-mode approach in radiation patterns and bandwidth. Following the rigorous investigation of the modal characteristics of the coupled half-width EH1 mode guided structure, a differentially fed, coupled, odd-leaky-mode, half-width, antenna design of size 1λ0 by 3.6λ0 (including the feed) is reported, showing measured maximum antenna gain of 11.6 dBi, 15% fractional bandwidth, gain flatness of 2.4 dB variation, and input return loss greater than 10 dB.

碩士<br>國立交通大學<br>電信工程系所<br>92<br>In this thesis, we propose two kinds of antenna structure: microstrip first higher order mode and single conductor second higher order mode. Generally, leaky wave antennas have the advantages: high gain, high radiation efficiency, low cost. In microstrip leaky wave antenna, we use aperture coupling with slot exciting first higher order mode. Because we want to leak the energy at our leaky wave antenna, we must use longer length at our antenna. For reducing the size, we let our antenna become ring, we can the same effect with original antenna. The single conductor leaky wave antenna has more bandwidth than the microstrip leaky wave antenna. In this thesis, we use coplanar waveguide(CPW) exciting second higher order mode, because of the characteristics in single conductor, the antenna pattern is end-fire.

博士<br>國立中山大學<br>光電工程研究所<br>93<br>We have developed a rigorous leaky-mode analysis on the antiresonant reflecting optical waveguides (ARROW’s) using a so-called “coupled electric (CE) coupled magnetic (CH) field method.” Radiation loss characteristics and the field distribution of the ARROW are analyzed in detail. Meanwhile, both the refractive indices and the thickness dependence for the isolation and distinction of modes are also investigated in this thesis. From the CE–CH method, the associated complex symmetric tridiagonal matrices are derived to solve the modal solutions via the eigenvalue-eigenvector technique. The uniquely designed formulation of CE–CH method yields better numerical properties, specifically in calculating the field distribution. This is suitable for any combination of materials and is capable of handling complex problems such as the leaky characteristics for both lossless and lossy cases. To quickly solve the complex roots of the ARROW, a set of accurate closed-form approximations for estimating both the field distribution and complex propagating constant have been derived from the CE–CH matrices. These first-order approximations provide six significant figures of the real part of the propagation constant

碩士<br>國立交通大學<br>電信工程系<br>87<br>A battery-free radio frequency identification card which incorporates a dual-beam angle-diversity leaky-mode antenna is presented. The integrated antenna is operated at 11.9 GHz. and shows 20.4 dBi directivity, 16.3 dB gain, and 3-dB beamwidth of (Az/El) 23/24. By placing a horn antenna at 2.5 meters away for receiving the coded, modulated signals from the transponder, we obtain the demodulated signals matched identically to the coding signals at the transponder.

碩士<br>南臺科技大學<br>機械工程系<br>105<br>In this study, we improved the positioning mechanism of the semi-cylindrical prism for the surface plasmon resonance （SPR） based sensor to reduce the noises from the reflected signal as well as the diffused signal to the PIN light sensor. With the help of the graphical control panel written in the Microsoft Visual Basic language for controlling the microstep motor, the leaky mode signal of surface plasmon resonance along the interface between the gold film of 50 nm thickness and the semi-cylindrical prism could be measured through the positioning mechanism. In principle, the SPR based sensor acquired the leaky mode signal without the reflected p-wave signal at the same ambient condition under the influence of different concentrations of each chosen analyte solution at different incident angles of the p-wave laser light polarized by the Glan-Thompson polarizer. In this study, three kinds of organic compounds including maltose （C12H22O11）, glucose （C6H12O6） and fructose （C6H12O6）, and three kinds of inorganic compounds including magnesium （Mg(NO3)2）, ammonium chloride （NH4Cl） and calcium chloride （CaCl2） were formulated into different concentrations of aqueous solutions. The test results showed that the leaky mode signal peak at the incident angles between 60˚ and 65˚ shift significantly for different compounds and concentrations. The relation of concentrations vs. incident angles obtained after the peak shift analysis for each analyte might be served as the benchmark for quantitative analysis of the same analyte in the future.

碩士<br>國立臺灣大學<br>電信工程學研究所<br>92<br>Abstract Due to its simplicity and efficiency, a full-vectorial mode solver based on a finite difference scheme is applied to investigate the propagation characteristics of optical waveguides. Since uniform meshes are used in the numerical implementation, it is very easy to divide the computational window of any arbitrary cross-sectional geometries of the waveguides. An index averaging technique is employed to deal with curved dielectric interfaces for stabilizing the numerical calculation and accelerating convergence. In addition, for solving leaky-mode problems, such as the investigation of waveguide confinement loss, the perfectly matched layer (PML) absorbing boundary condition is incorporated into our finite difference formulations. The influence of the index averaging technique on the leaky-mode analysis is also discussed. We employ the shift inverse power method (SIPM) for solving the formulated eigenvalue problems. In this work, both one-dimensional and two-dimensional problems are considered, including the slab waveguide, the antiresonant reflecting optical waveguide (ARROW), the step-index optical fiber, the rectangular channel waveguide, the anisotropic embedded-channel LiNbO3 integrated optical waveguide, and microstructured optical fibers (MOFs). Comparsion of our calculation with other methods is discussed.

碩士<br>國立交通大學<br>電信工程系<br>87<br>The finite ground plane effects on the first higher-order mode and the dominant mode of a microstrip is presented. Two special cases of the finite ground plane (the symmetric structure and the reverse structure) are discussed in this thesis. A new additional leaky mode is reported. We introduce the current distributions and the dispersion characteristics of this mode.