Imaginémonos un circuito eléctrico en el plano xy, de forma totalmente arbitraria, intensidad I y una línea serpenteante L que se desplaza en la dirección del eje z, desde z = - ∞ hasta z = + ∞. La corriente I genera campos magnéticos B en todos los puntos del espacio. Si se nos planteara la siguiente pregunta: Cuánto vale la integral de línea del campo B a lo largo de la curva L, la pregunta nos parecería bastante descabellada, pues no se precisa la forma del circuito ni de la línea L, omisiones que impiden iniciar cálculo alguno. Aún en el caso que se supiera la forma exacta del circuito, no es una tarea nada fácil calcular el campo B, menos aún su integral a lo largo de L. Sin embargo, lo cierto es que sí existe una respuesta al problema y es muy sencilla su obtención empleando la Ley de Ampere.

In this dissertation we study The Refractor Problem and its analytic formulation which leads to Monge-Ampere type equation. This problem can be described as follows: Suppose that A and B are two domains of the unit sphere in n dimensions and g and f are two positive functions integrable on A and B respectively. Consider two homogeneous, isotropic media; medium I and medium II, which have different optical densities and assume that from a point O inside medium I, light emanates with intensity g(x); where x is in A. When an incident ray of light hits an interface between two media with different indices of refraction, it splits into two rays a reflected ray that propagates back into medium I and a refracted ray that proceeds into medium II. Consequently, the incident ray loses some of its energy as it proceeds into medium II. By using Fresnel equations, which are consequences of Maxwell's Equations, one can determine precisely how much of the energy is lost due to internal reflection. The problem is to take into account this loss and construct a surface such that all rays emitted from a point O in the first medium, with directions in A are refracted by the surface into media II with directions in B and the prescribed illumination intensity received in the direction m, where m is in B is f(m). We propose a model to this problem. We introduce weak solutions for the problem and prove their existence by using approximation by ellipsoids or hyperboloids depending on whether n1 is less than n2 or n1 is greater than n2. We will also prove that a solution of the problem satisfies a Monge-Ampere type of PDE. / Mathematics

We introduce two models to design near field reflectors in R^3 that solve an inverse problem in radiometry, taking into account the inverse square law of irradiance. The problem leads to a Monge-Ampere type inequality. The surfaces in the first model are strictly convex and require to be far from the source to avoid obstruction. In the second model, the reflectors are neither convex nor concave and do not block the rays even if they are close to the source. / Mathematics

This thesis proposes an enhanced ampere-hour counting method based on the depth-of-discharge (DOD) to estimate the state-of-charge (SOC) and state-of-health (SOH) for lead-acid batteries. Not only the losses at different discharging currents, but also the releasable capacity at the exhausted state caused by the larger discharging current are considered and compensated. Furthermore, the SOH is revaluated at the exhausted state by the maximum releasable capacity, consequently leading to more accurate SOC estimation. Through the experiments that emulate practical operations, the experimental results reveal that the maximum error is less than 6 %.

Modeling of electrical machines play a very important role in a variety of applications such as performance analysis, characterization, fault diagnosis, condition monitoring and stress analysis of the machines. One of the important parameter while modeling the electrical machine is the magnetic characteristics of the core material. This plays a huge role in the performance characteristics and analysis of the electrical machines. Existing techniques available to determine the magnetic characteristics of a material are mainly Epstein and single sheet tester. These two tests are invasive and destructive method of testing the magnetic characteristics of the material. This research work takes up this problem and comes with a simple yet effective solution to determine the average magnetic characteristics of the material in the salient pole synchronous machine (SPSM). An FE model of the SPSM was developed to closely emulate the characteristics of the experimental machine. This FE model was first subjected to magnetostatic simulation under different field currents using a known magnetic material. Ampere turn distribution technique was used to determine the magnetic characteristics of the material. Following the determination of the new material, this material was used in the FE simulation of the SPSM running as a motor and a generator under varying load condition and field currents. Then these results were compared with the real machine to determine the effectiveness of the developed scheme. / Graduate

Les pompes à électrons ont été très étudiées et fabriquées par le monde scientifique. Elles génèrent un courant continu proportionnel à une fréquence très bien contrôlée en métrologie. Dans ce contexte métrologique, des principes et matériaux divers comme la pompe en GaAs ou Silicium ou encore le tourniquet supraconducteur ont marqué les avancées. Bien que les courants générés sont toujours plus grands et précis, les exigences fixées pour la métrologie sont difficiles à atteindre et pour l'heure aucune pompe à électrons ne peut être utilisable pour la mise en pratique du futur ampère quantique qui sera probablement défini dans quelques années.Par ailleurs, des chercheurs ont créé des circuits associant des transistors FETs (transistors à effet de champ) et des transistors SETs (transistors mono-électroniques), notamment dans une optique d'une électronique très basse consommation.Cette thèse apporte une contribution nouvelle dans ces deux domaines : une nouvelle pompe à électrons en silicium a été développée, et une co-intégration de circuit CMOS classique avec un dispositif de nanoélectronique quantique a été démontré.Notre pompe à électrons repose sur le principe de deux barrières tunnel réglables et d'un îlot central. Au travers de la modulation des barrières à la fréquence f, la charge électrostatique de l'îlot central est contrôlée, un courant continu I=ef est généré; et ceci même avec une tension nulle aux bornes de la pompe. Nos pompes à électrons utilisent la technologie nanofils silicium-sur-isolant développée par le CEA-LETI. Le nanofil est recouvert de deux grilles (2 MOSFETs en série) pour les barrières réglables, et un îlot de Coulomb métallique de petite taille est « isolé » entre ces deux transistors. Nos échantillons à 100mK nous ont permis de montrer que nous étions capables de contrôler adiabatiquement l'état de charge de l'îlot quantique et de générer des courants quantifiés jusqu'à 900MHz. Nous avons aussi fabriqué les premières pompes à électrons en lithographique optique uniquement, avec pour ces dernières une fréquence maximale de pompage de 300MHz.Notre technologie de fabrication de SETs à grande échelle repose sur une réduction des tailles. Ces techniques n'ont que très rarement été couplées avec des circuits CMOS conventionnels mais fonctionnant à basse température. L'intérêt d'une telle co-intégration est grand dans le domaine de l'information quantique: la mise en place de beaucoup de qubits couplés pourrait nécessiter des circuits « annexes » réalisés en CMOS classique mais cryogénique.Nous avons conçu et fabriqué avec le LETI-DACLE un circuit co-intégrant un circuit oscillant composé de FETs de grandes dimensions et un circuit nanoscopique composé de SETs. Un circuit d'essai comprenant une pompe à électrons pilotée sur la puce par un circuit oscillant a été réalisé et mesuré à basse température.Nos résultats montrent que les circuits oscillants basés sur des oscillateurs en anneaux pour des applications à 300K restent fonctionnels jusqu'à 1K, malgré une très faible baisse de la fréquence d'oscillation. En parallèle, nous avons par la mesure de courant de rectification sur le dispositif nanoscopique mis en évidence que la cohabitation entre circuit FET et SET était réalisable et qu'il est possible d'imaginer un circuit complexe pour réaliser une pompe à électrons et son électronique associée sur une même puce.La conception de pompe à électrons par l'approche de la technologie SOI a montré sa viabilité, avec nos dispositifs potentiellement équivalents aux meilleures pompes crées jusqu'à présent. L'avantage du silicium et des techniques de fabrication modernes ont prouvé qu'il était possible de créer des circuits complexes alliant FET et SET pour des applications faisant intervenir des phénomènes quantiques. Ces travaux montrent le caractère prometteur de la co-intégration de circuits et ouvre la voie à de plus amples investigations dans la réalisation des pompes à électrons en silicium. / Electrons pumps have been extensively studied and manufactured by the scientific world. They generate a DC current proportional to a frequency very well controlled metrology. In this metrological context, the various principles and materials such as GaAs or Silicon pump or the superconducting turnstile have shown great progress. Although the generated level of currents are always higher and accurate, the requirements for the metrology are difficult to meet and for now no electron pump can be used for the realisation of the future quantum ampere that will probably be defined in a few years.Moreover, researchers have created circuits involving transistors FETs (field effect transistors) and transistors SETs (single-electron transistors), particularly to the purpose of a low consumption electronic.This thesis makes a further contribution in both areas: a new silicon electron pump was developed and co-integration of conventional CMOS circuit with a quantum nanoelectronics device was demonstrated.Our electron pump is based on the principle of two tuneable tunnel barriers and a central island. Through the modulation of the barriers at the frequency f, the electrostatic charge of the central island is controlled, a direct current I = ef is generated; and this even with a zero voltage bias across the pump. Our electron pumps use the nanowire technology silicon-on-insulator developed by CEA-LETI. The nanowire is covered with two gates (two MOSFETs in series) as adjustable barriers, and a small metallic Coulomb island is "isolated" between these two transistors. Our samples at 100mK demonstrated that we were able to control the quantum island charge state adiabatically and generated quantified currents up to 900MHz. We also produced the first electron pumps only achieved by optical lithography, with a maximum pumping frequency of 300MHz.Our large scale SETs manufacturing technology is based on the extreme size shrinking. These techniques have rarely been coupled with conventional CMOS circuits, when operating at low temperature. The interest of such co-integration is strong in the field of the quantum information: the establishment of many coupled qubits may require "additionnal" circuits made with classic CMOS but in cryogenic environnement.We designed and fabricated with the LETI-DACLE a co-integration of an oscillating circuit composed of large FETs circuit and a circuit made of nanoscopic SETs. A test circuit comprising an electron pump driven on chip by an oscillating circuit was created and measured at low temperature.Our results show that the oscillating circuit based on ring oscillators for 300K applications remain functional up to 1K, despite a very slight decay in the oscillation frequency. In parallel, by measuring a rectification current on the nanoscale device we demonstrated that cohabitation between FET circuit and SET was realistic and makes possible to imagine a complex circuit to achieve an electron pump and its electronic embedded on a single chip.The electron pump design by the approach of SOI technology has demonstrated its viability, potentially our devices are equivalent versus the best pumps created so far. The advantage of silicon and modern manufacturing techniques have proved that was possible to create complex circuits combining FET and SET for applications involving quantum phenomena. This work shows the promising nature of the co-integration circuits and opens the way for further investigation in the implementation of silicon electron pumps.

Perovskite solar cells are part of third generation of solar cells and thanks to their atractive properties they are potencional candidates for replacement of silicon solar cells. Inverted planar structure of perovskite solar cells is possible to prepare by low temperature methods and by solution processing techniques. Main aim of this thesis was to prepare and characterize inverted planar perovskite solr cells with a different modification of structure. Perovskite solar cells was prepared with following structures: reference perovskite solar cells, perovskite solar cells with only a perovskite layer, perovskite solar cell without electron transport and perovskite solar cell without hole transport layer. They were prepared simultaneously by spin coating. Methods used for a characterisation of a parameters of this cells were current-voltage characteristic, impedance spektroskopy, meassure of external quantum efficiency and electrolumiscence. Reference perovskite solar cell reached best results folowed by solar cell without hole transport layer. Lowest results were gained by perovskite solar cell without electron transport layer and perovskite solar cell with only perovskite layer, where increased recombination and acumulation of charge were observed,

In a world with a growing population there is a trend toward higher and higher energy usage. Because of the cost involved in producing extra energy, there is a need for more efficient usage of the energy that is already available. The issue of efficiency rings home especially clear with electric motors. Although induction motors are used in many different applications, the motors used in electric vehicles must be able to generate a large starting torque as well as operate over a wide speed range. This work analyzes the restrictions placed on the motor and inverter drive system. It also looks at the best method for controlling the drive in order to achieve the highest efficiency out of the drive. While other works have shown methods of achieve high efficiency out of the motor, it is the assertion of this work that the efficiency of the total drive is more important. It is to that end that this work analyzes the performance of an induction motor under low torque and speed where a traction drive utilizes the most energy. / Master of Science

This thesis studies State-of-Charge (SOC) method for widely used lead-acid batteries and the most prospective lithium-ion batteries. First, the relationship between the battery capacity and the open-circuit-voltage under different charging/discharging currents is investigated based on the equivalent circuit. Experimental results indicate that the open-circuit-voltage of the lead-acid battery varies regularly with the charging/discharging current and the duration of time for the battery disconnected from the load. Accordingly, a dynamic open-circuit-voltage method in considerations the open-circuit-time and the previous operating current is capable of precisely estimating the battery capacity in a shorter time. As for the lithium-ion batteries, their charging/discharging characteristics reveal that the Coulomb/Ampere-Hour Counting method is capable of yielding accurate estimations. Finally, through the experiments that emulate practical operations, the SOC estimations of batteries are verified to demonstrate the effectiveness and accuracy of the proposed methods.

Orientador: André Koch Torres de Assis / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-12T11:28:52Z (GMT). No. of bitstreams: 1 Chaib_JoaoPauloMartinsdeCastro_D.pdf: 18802562 bytes, checksum: 7a37bc6728a03158752193708b51fb64 (MD5) Previous issue date: 2009 / Resumo: Apresentamos a força de Ampère entre elementos de corrente e discutimos detalhadamente as grandezas que aparecem nesta lei. Analisamos o caminho percorrido por Ampère para chegar na sua força entre elementos de corrente. Mostramos suas primeiras experiências, as formulações iniciais de sua força, as experiências de Biot e Savart, assim como a in u¿encia da experiência da rotação contínua de Faraday na determinação do valor final da força entre elementos de corrente de Ampère. Apresentamos os diversos casos de equilíbrio introduzidos por Ampère e sua relevância metodológica na obtenção de leis quantitativas na física. Mostramos as contribuições de Savary na elaboração das consequências quantitativas da força de Ampère e o impacto que elas tiveram sobre Biot, Savart e Ampère. Discutimos alguns dos principais trabalhos, cartas e manuscritos de Ampère, desde 1820 até sua obra máxima de 1826, o Théorie des Phénomènes Électro-dynamiques, Uniquement Déduite de l¿Expérience. Apresentamos uma tradução completa desta obra e das notas que a acompanham. / Abstract: We present Ampère¿s force between current elements and discuss in detail the magnitudes which appear in this law. We analyze the trajectory followed by Ampère in order to obtain his force between current elements. We show his first experiments, the initial formulations of his force, the experiments of Biot and Savart, and the in uence of Faraday¿s experiment of uninterrupted rotation in the determination of the final value of Ampère¿s force between current elements. We present the several cases of equilibrium introduced by Ampère and their methodological relevance in order to obtain quantitative laws in physics. We show the contributions of Savary for the elaboration of the quantitative consequences of Ampère¿s force and the impact they had upon Biot, Savart and Ampère. We discuss some of the main works, letters and manuscripts of Ampère, from 1820 until his masterpiece of 1826, the Théorie des Phénomènes Électro-dynamiques, Uniquement Déduite de l¿Expérience. We present a complete translation of this work and of the notes which follow it. / Doutorado / Física / Doutor em Ciências