Thesis (Ph.D.)--University of Texas at Dallas, 2009. / Includes vita. Includes bibliographical references (leaves 132-138)

Made available in DSpace on 2016-08-29T15:33:36Z (GMT). No. of bitstreams: 1 tese_6439_Dissertação_LUCIANA_ZAMPROGNE.pdf: 7921443 bytes, checksum: fe99f46f851d84a696a6319b811a04ee (MD5) Previous issue date: 2013-03-19 / A presente dissertação tem como objetivo analisar a construção social da adolescência através das histórias em quadrinhos da Turma da Mônica Jovem. Pretende-se demonstrar como tais narrativas quadrinísticas expressam valores sociais e depreendem elementos simbólicos, com foco na subcategoria que denominamos Teen, dentro das concepções de adolescências contemporâneas. Ressalta-se que os quadrinhos nesta pesquisa serão entendidos como um artefato cultural, e que, portanto, refletem valores e posições da sociedade em suas produções.

In this paper, an asymmetric compact multiband slot antenna is proposed for global positioning system (GPS), worldwide interoperability for microwave access (WiMAX), and wireless area network (WLAN) applications. The top plane, a ground is composed of a rectangular slot with a trapezoidal-like stub, an inverted U-shaped slot at the right side of the rectangular slot, an inverted L-shaped slot at the left side of the rectangular slot, and three stubs. The proposed antenna is fed by an asymmetric cross-parasitic strip on the bottom plane. By properly designing the slots and stubs, four resonant frequency bands are achieved with -10 dB reflection coefficient bandwidths of 50 MHz, 400 MHz, 390 MHz, and 830 MHz in the 1.57 GHz GPS band, 2.4 GHz WLAN band, 3.5 GHz WiMAX band, and 5.5 GHz WLAN bands, respectively. The antenna has a total compact size of 13 mm x 32 mm x 0.8 mm. Simulated and measured results indicate that the proposed antenna has sufficient bandwidth and good radiation performance in each band.

In this thesis we examine the theoretical origin and statistical features of the Cosmic Microwave Background radiation. We particularly focus on the CMB power spectra and cosmological parameter estimation from QUaD CMB experiment data in order to derive implications for the concordance cosmological model. In chapter 4 we present a detailed parameter estimation analysis of the combined polarization and temperature power spectra from the second and third season observations of the QUaD experiment. QUaD has for the first time detected multiple acoustic peaks in the polarization spectrum, allowing meaningful parameter analyses from the polarization data alone. In a standard 6-parameter ACDM parameter estimation analysis we find the QUaD TT power spectrum to be in very good agreement with previous results. However, the QUaD polarization data shows some tension with ACDM model. The origin of this 1−2σ tension remains unclear, and may point to new physics, residual systematics or simple random chance. Combining polarization and temperature data we find an acceptable fit, and show that our results are dominated by the polarization signal. We combine QUaD with the five-year data from the WMAP satellite and the SDSS Luminous Red Galaxies 4th data release power spectrum, and extend our analysis to constrain the tensor-to-scalar ratio and the primordial isocurvature perturbations. Our analysis sets a benchmark for future polarization experiments. In chapter 5 we outline and test a new semi-analytical approach for the estimation of the pseudo- temperature and polarization CMB power spectra for experiments with incomplete sky coverage. We propose a method for constructing the mode-mode coupling matrices which connect the temperature and polarization pseudo-Cℓ’s to the unbiased all-sky bandpowers in the flat sky approximation. We apply this method to the apodization masks of the QUaD CMB experiment and we show that the true underlying bandpowers can be reconstructed from the simulated QUaD-like pseudo-Cℓ’s to high precision. We further investigate the possibility of extending the proposed analytical flat sky approach to the exact calculation of the PCL covariance matrices over a large range of multipoles and we find that the numerical calculation is extremely computationally expensive. The flat sky pseudo-Cℓ and covariances methods presented in this chapter are still work in progress and require more testing.

Ingeniero Civil Eléctrico / En esta Memoria de Título se diseñó y se implementó un sistema de control asistido para una plataforma de vuelo no tripulada (Unmanned Aerial Vehicle - UAV). Lo anterior se realizó con el propósito de simplificar el proceso de aprendizaje de operación radio-controlada a través de un mando de 4 canales. La plataforma utilizada correspondió a un quad-rotor, nave consistente en un cuerpo y cuatro hélices propulsoras. La tele-operación de UAVs constituye una tarea de lento aprendizaje debido a diversos factores como la dinámica de vuelo y la familiaridad del operario con los mandos. El principal objetivo del trabajo es el diseño y la implementación de un sistema que evalúe el desempeño del operario a través de un análisis de sus instrucciones y de la evolución de la nave, y que actúe a nivel de los controladores, facilitando en alguna medida el manejo de la nave. Este trabajo se realizó con el apoyo del Grupo de Automatización del Centro Avanzado de Tecnología para la Minería (AMTC). La metodología de trabajo consistió, en primer lugar, en la integración de la plataforma aérea. Esta tarea incluyó el montaje de la estructura principal, la unión de todos los componentes mecánicos y electrónicos, el diagnóstico de los módulos utilizados, la instalación de un programa núcleo (firmware) de código abierto (APM: Copter), y la sintonización inicial de parámetros. Una vez lista la plataforma, se estudió el código fuente para determinar el tipo de asistente que se utilizaría. Posteriormente, se diseñó un sistema asistente de vuelo en base a pruebas de vuelo y un post-procesamiento de los datos realizado fuera de línea. Los sensores disponibles incluían las unidades de medición inercial, consistentes en acelerómetros y giróscopos, además de magnetómetros. Estos sensores no permitían una estimación adecuada de la posición de la nave, por lo que se consideró además la realización de simulaciones en base a los comandos entregados por el operario al momento dar la prueba. Se utilizó un simulador compatible con el código fuente utilizado y se escribió un programa en Python para enviar las órdenes al simulador mediante el protocolo de comunicación Mavlink y obtener coordenadas simuladas aproximadas. Posteriormente se creó un programa en MATLAB para analizar los resultados de ambas pruebas. Por otro lado, se modificó el código fuente, escrito en C++, creando un modo de vuelo que filtra las referencias entregadas a los controladores PID de alto nivel en función de dos parámetros que deben ser ajustados manualmente. Se realizaron pruebas con diferentes operarios para verificar tanto el funcionamiento del simulador como del asistente de vuelo. Las simulaciones realizadas entregaron resultados imprecisos, con valores llegando sobre los 100 [m] para pruebas que no tuvieron desplazamientos superiores a los 3 [m]. Se consideró apropiado descartar su uso para la obtención de parámetros. Con ellos, se realizaron pruebas de operación para mostrar el efecto del asistente. Los operarios mostraron un grado de mejoría en las pruebas, específicamente pudiendo controlar la altitud de la plataforma con más estabilidad. Se obtuvieron oscilaciones lentas en los ángulos, sin embargo se mantuvieron dentro de rangos estables. Se concluyó que el asistente logra efectivamente intervenir de manera positiva en la estabilización de la nave, ayudando al control de los ángulos horizontales. Esto permite al usuario en primer lugar aprender a controlar la aceleración de la nave. Se proponen mejoras al trabajo, incluyendo la posible utilización de sensores de mayor precisión como GPS para la posición o láser o sonar para la altitud, lo que permitiría la posibilidad de asistir el control de aceleración y de obtener lecturas menos erráticas.

This dissertation covers the process of modelling and subsequently developing a flight dynamics controller for a quad–rotor unmanned aerial vehicle. It is a theoretical study that focusses on the selection of a controller type by first analysing the problem on a system level and then on a technical level. The craft is modelled using the Newton– Euler model, accounting for multiple reference frames to account for the interpretation of orientation as seen by on–board sensors. The quad–rotor model and selected controllers are characterized and compared. The model is verified through simulation by comparison to a validated model. A series of generic control loops are derived and used as reference for the implementation of the controllers. A Simulator is developed and used to do a comparative study of the various controller types and the control approach. Finally a full simulation is done to demonstrate the interaction between the controllers. / Thesis (MIng (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2012.

This dissertation covers the process of modelling and subsequently developing a flight dynamics controller for a quad–rotor unmanned aerial vehicle. It is a theoretical study that focusses on the selection of a controller type by first analysing the problem on a system level and then on a technical level. The craft is modelled using the Newton– Euler model, accounting for multiple reference frames to account for the interpretation of orientation as seen by on–board sensors. The quad–rotor model and selected controllers are characterized and compared. The model is verified through simulation by comparison to a validated model. A series of generic control loops are derived and used as reference for the implementation of the controllers. A Simulator is developed and used to do a comparative study of the various controller types and the control approach. Finally a full simulation is done to demonstrate the interaction between the controllers. / Thesis (MIng (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2012.

Modeling the motion that occurs between frames of a video sequence is a key component of video coding applications. Typically it is not possible to represent the motion between frames by a single model and therefore a quad-tree structure is employed where smaller, variable size regions or blocks are allowed to take on separate motion models. Quad-tree structures however suffer from two fundamental forms of redundancy. First, quad-trees exhibit structural redundancy due to their inability to exploit the dependence between neighboring leaf nodes with different parents. The second form of redundancy is due to the quad-tree structure itself being limited to capture only horizontal and vertical edge discontinuities at dyadically related locations; this means that general discontinuities in the motion field, such as those caused by boundaries of moving objects, become difficult and expensive to model. In our work, we address the issue of structural redundancy by introducing leaf merging. We describe how the intuitively appealing leaf merging step can be incorporated into quad-tree motion representations for a range motion modeling contexts. In particular, the impact of rate-distortion (R-D) optimized merging for two motion coding schemes, these being spatially predictive coding, as used by H.264, and hierarchical coding, are considered. Our experimental results demonstrate that the merging step can provide significant gains in R-D performance for both the hierarchical and spatial prediction schemes. Hierarchical coding has the advantage that it offers scalable access to the motion information; however due to the redundancy it introduces hierarchical coding has not been traditionally pursued. Our work shows that much of this redundancy can be mitigated with the introduction of merging. To enable scalable decoding, we employ a merging scheme which ensures that the dependencies introduced via merging can be hierarchically decoded. Theoretical investigations confirm the inherent advantages of leaf merging for quad-tree motion models. To enable quad-tree structures to better model motion discontinuity boundaries, we introduce geometry information to the quad-tree representation. We choose to model motion and geometry using separate quad-tree structures; thereby enabling each attribute to be refined separately. We extend the leaf merging paradigm to incorporate the dual tree structure allowing regions to be formed that have both motion and geometry attributes, subject to rate-distortion optimization considerations. We employ hierarchical coding for the motion and geometry information and ensure that the merging process retains the property of resolution scalability. Experimental results show that the R-D performance of the merged dual tree representation, is significantly better than conventional motion modeling schemes. Theoretical investigations show that if both motion and boundary geometry can be perfectly modeled, then the merged dual tree representation is able to achieve optimal R-D performance. We explore resolution scalability of merged quad-tree representations. We consider a modified Lagrangian cost function that takes into account the possibility of scalable decoding. Experimental results reveal that the new cost objective can considerably improve scalability performance without significant loss in overall efficiency and with competitive performance at all resolutions.

Stuttgart, Univ., Diplomarb., 2003.

This diploma thesis deals with design Quads. Specifically, a type of terrain utility quad, often referred to as the ATV. To drive the machine uses two electric motors. The ultimate designer's proposal responds to the significant social trends that support the economy and ecological design. These parameters together with the yield of the machines are non-traditional solutions to this type of field machinery.