ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / The theoretical capacity of communication channel in the presence of additive white Gaussian noise (AWGN) as defined by Shannon's channel capacity theorem has been well understood since 1940s. This theorem bounds the bit error rate (BER) of RF data links achievable for a particular noise level. The development in digital technology over the last decade has made it possible not just to design devices that operate close to the Shannon's limit, but also to explore techniques, such as best source and best data selectors, for further improvements in performance of RF data links where frequency, spatial or polar diverse reception is possible. This paper discusses an approach to improving quality of data links using an advanced diversity technique that does not select one source at a time but aligns and combines soft values from each. It shows how the overall bit error rate of RF data link can be improved by combining signals from multiple receivers and/or transmitters. Test results showing practical performance improvements are presented and discussed.

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SCADA is the primary system for control and monitoring of distribution grids. As the expectations on how the grid must operate changes with the increased use of renewable energy sources, it also requires new methods of monitoring. Phasor Measurement Units (PMU) measures the phase angle and amplitude synchronously with GPS. A collaboration between U.C Berkeley and Power Standard Lab researches the possibilities of implementing synchrophasors in distribution grids. These devices are called micro-PMU and will provide similar services available for transmission grids, though adapted for lower voltage levels. Synchrophasors are useful in the development of a smarter distribution network, which consequently makes them interesting for the Swedish electricity market. Martin Gahr, a student at Berkeley / ETH, has developed a method to determine the topology of a distribution grid using micro-PMU's. The method compares calculated values from SCADA with values from micro-PMU's. The smallest difference between the two readings clarifies the topology. In this thesis the method is used to study an existing distribution grid in central parts of a medium-sized Swedish city. The method gives a satisfactory result when it is implemented on the mashed parts of the distribution grid. There are also indications that micro-PMU's must not be placed at every node to provide a reliable result. Although the method seems to be working on mashed parts of a Swedish distribution grid, it is not particulary interesting to implement the method in reality.

Adaptive array antennas use has been limited to non-commercial applications due to their high cost and hardware complexity. The implementation cost of adaptive array antennas can be kept to a minimum by using cost effective antennas, reducing the number of elements in the array and implementing efficient beamforming techniques. This thesis presents techniques for the design of adaptive array antennas which will enable their cost effective implementation in wireless communication systems. The techniques are investigated from three perspectives, namely, reconfigurable antenna design, wide scan array design and single-port beamforming technique. A novel single-feed polarisation reconfigurable antenna design is proposed in the first stage of this study. Different polarisation states, namely, linear polarisation (LP), left-hand circular polarisation (LHCP) and right-hand circular polarisation (RHCP), are achieved by perturbing the shape of the main radiating structure of the antenna. The proposed antenna exhibits good axial ratio (< 3 dB at 2.4 GHz) and has high radiation efficiency in both polarisation modes (91.5 % - LHCP and 86.9 % - RHCP). With a compact single feeding structure, the antenna is suitable for implementation in wireless communication devices. The second stage of the study presents the design procedure of wide scan adaptive array antennas with reduced number of elements. Adaptive array antennas with limited number of elements have limited scanning range, reduced angular scanning resolution and high sidelobe levels. To date, design synthesis of adaptive array antennas has been targeted on arrays with a large number of elements. This thesis presents a comprehensive analysis of adaptive array antennas with less than 10 elements. Different array configurations are analysed and various array design parameters such as number of elements, separation between elements and orientation of the elements are analysed in terms of their 3 dB scan range. The proposed array, the 3-faceted array, achieves a scanning range up to ±70°, which is higher than ±56° obtained from the Uniform Linear Array. The faceted arrays are then evaluated in the context of adaptive beamforming properties. It was shown that the 3-faceted array is suitable for adaptive array applications in wireless communication systems as it achieves the highest directivity compared to other faceted structures. The 3-faceted array is then synthesised for low sidelobe level. Phase correction together with amplitude tapering technique is applied to the 3-faceted array. The use of conventional and tuneable windowing techniques on the 3- faceted array is also analysed. The final stage of the study investigates beamforming techniques for the adaptive array antenna. In the first part, beamforming algorithms using different performance criteria, which include maximum signal-to noise-ratio (SINR), minimum (mean-square Error) MSE and power minimisation, are evaluated. In the second part, single-port beamforming techniques are explored. In previous single-port beamforming methods, the spatial information of the signals is not fully recovered and this limits the use of conventional adaptive beamforming algorithms. In this thesis, a novel signal estimation technique using pseudo-inverse function for single-port beamforming is proposed. The proposed polarisation reconfigurable antenna, the 3-faceted array antenna and the single-port beamforming technique achieve the required performance, which suggests the potential of adaptive array antennas to be deployed commercially, especially in wireless communication industry.

published_or_final_version / Business Administration / Master / Master of Business Administration

published_or_final_version / Computer Science / Master / Master of Philosophy

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Ingeniero Civil Eléctrico / El sistema eléctrico chileno deberá dar el siguiente paso si es que se quiere seguir con los lineamientos de energías limpias y eficiencia energética. La adaptación de la urbe a una más "inteligente" podría brindar la solución a la mayoría de los problemas concernientes a su integración, dándole también la oportunidad a nuevas tecnologías que favorecerían esta nueva ideología. Respecto a la integración y sus problemas, se resalta en esta ocasión la referente a frecuencia: se hará cada vez más notorio con la inserción de ciertas ERNC (generación sin inercia), por lo que se plantea la elaboración de un esquema de desconexión selectiva de cargas para paliar el efecto de falta de inercia en situaciones de contingencia. La elaboración, prueba, validación y evaluación del esquema fue realizada en el entorno DIgSILENT; ajustándose los parámetros necesarios mediante procesamiento de datos de perfil de consumo en la capital y apuntando a aplicaciones específicas que cumplieran un set de requisitos. Como comparación, se utilizan casos de estudios similares a los emitidos por la DO del CDEC para los estudios de EDAC. Los resultados finales auguran un buen desempeño en la parte técnica. Los beneficios percibidos apuntan a mejores niveles de frecuencia, pudiendo impedir la activación de hasta 4 etapas de EDAC si se enfoca y diseña apropiadamente el esquema. La flexibilidad del diseño permite priorizar resultados tanto para ciertos parámetros de evaluación, como para la magnitud de fallas que se quiera soportar. Económicamente aportaría ahorros no menores en una ventana de tiempo adecuada, aunque siendo sus atractivos principales el aporte técnico/operacional y el de formar parte de uno de los tantos esquemas aplicables que sustentarían la instalación de medidores inteligentes.

Designing Dynamic Textile Patterns Progress in chemistry, fibres and polymers technology provides textile designers with new expressive materials, making it possible to design dynamic textile patterns, where several different expressions are inherent in the same textile, textiles that, for example, could alternate between a striped and checkered pattern. Textiles are traditionally designed and produced to keep a given, static expression during their life cycle; a striped pattern is supposed to keep its stripes. In the same way textile designers are trained to design for static expressions, where patterns and decorations are meant to last in a specific manner. However, things are changing. The textile designer now deals also with a new raw material, a dynamic textile, ready to be further designed, developed and/or programmed, depending on functional context. This transformation in practice is not an easy one for the designers. Designers need to learn how to design with these new materials and their specific qualities, to be able to develop the full expressional potential inherent in “smart textiles design”. The aim of this thesis is to display, and discuss, a methodology for designing dynamic textile patterns. So far, something that mainly has been seen in different experimental and conceptual prototypes, in artistic expressions and for commercial efforts etc. In terms of basic experimental research this thesis explores the turn in textile design practice through a series of design experiments with focus on contributing to identifying and characterizing new design variables, new design methods and new design techniques as a foundation for dynamic textile patterns. / <p>Disputationen sker den 1:a juni 2010, kl. 13.00 i Textilmuseet, Druveforsvägen 8, Borås. Opponent: Senior Lecturer, Mary- Ann Hansen, Danmarks Designskole, Denmark</p>