The Mbesese Initiative for Sustainable Development (MISD) is a group aiming to help eliminate extreme poverty in Africa by creating educational opportunity. One project that the group is currently doing is to build Same Polytechnic College (SPC) in Tanzania. As part of the project, this thesis aims to study and analyze the electrical power system and distribution for the college. Based on the projected load profile of the college and high potential for solar generation in Tanzania, several different power systems utilizing local utility AC electricity and/or photovoltaic (PV) DC electricity are explored and simulated for their feasibility and performance. Analysis of each design is presented and compared to determine the most viable system based on reliability, costs, and space. Results of the study indicate that over designing the DC system may generate wasteful energy while under designing the DC system may cause the overall system to rely heavily on the AC power grid. Ultimately, this thesis demonstrates that integrating a 58.9% DC system mixed with AC system offers the highest payback while efficiently utilizing the PV system, the battery system, and provided land.

M. Ing. / Solar powered UAV's have gained world wide attention with aircraft such as Solar Impulse and Quinetiq's Zephyr. UAV's in general are becomming increasingly popular, in 2006 80% of all US military ights over Iraq were UAV ights [38]. UAV's are the the most dynamic growth sector in the world aerospace industry having spent $3:4 billion in 2008 and is expected to be $5:8 billion in 2014. Solar Impulse has a budget of $94 million, Quinetiq has been awarded a $44:9 million contract to build 7 zephyrs. NASA has had several solar powered UAV projects. With advancements in solar and battery technologies solar powred UAV's are fast becomming a reality. The disadvantage of projects such as the Solar Impulse, Zephyr, Solong and Sky Sailor is they have extremely large budgets and have access to non commercial and highy specialized Chapter 1 | Problem Statement 10 products. The main purpose of the project is to develop a solar power system using only commercial products which can substancially increase the ight time of a UAV under sunny conditions. The project has several advantages: The project also provides a clean, green energy aspect. Because the energy provided by the solar cells is free and has no carbon footprint, the project is environmentally friendly; The project uses only commercially available products so it can easily be implemented and reproduced; The system developed for the project is not only limited to UAV's/ the project can be used in other applications such as Solar powered cars or robots. Due to the commercial nature of the big 4 solar aircraft information about their solar power systems is not easily available. The work presented here is an acedemic venture and will be freely available The project has many unknowns such as the size of the UAV, power requirements and available components. The research methodolgy used allows the unknowns to be determined using mathematical models and simulations. The models and simulations are further veri ed and altered accordingly to the actual implementation of the system. The project provides a step by step procedure to building a power system for a solar powered UAV. There are several building blocks in the project. Each building block forms a vital part of the system but can also be designed and implemented as a sigle entity. Only once each building block has achieved its own indavidual speci cations will they be integrated together to form the complete system. There are many risks and limitations within the project. The project is dependant on the type of UAV with respect to power requirements. Therefore the power system needs to provide as much solar power as possible to the UAV. If the available solar power is not su cient for level ight, the solar power must supliment the original power supply of the aircraft in a safe manner. There are many dangers when ying a UAV, if the UAV loses control it could potentially injure or even kill a person. Therefore outmost care needs to be taken to mitigate these risks. By the end of the project a solar power supply, capable of powering a UAV, will be delivered. With the given resources and the current state of technology the project should be a success.

abstract: Ultrasound B-mode imaging is an increasingly significant medical imaging modality for clinical applications. Compared to other imaging modalities like computed tomography (CT) or magnetic resonance imaging (MRI), ultrasound imaging has the advantage of being safe, inexpensive, and portable. While two dimensional (2-D) ultrasound imaging is very popular, three dimensional (3-D) ultrasound imaging provides distinct advantages over its 2-D counterpart by providing volumetric imaging, which leads to more accurate analysis of tumor and cysts. However, the amount of received data at the front-end of 3-D system is extremely large, making it impractical for power-constrained portable systems. In this thesis, algorithm and hardware design techniques to support a hand-held 3-D ultrasound imaging system are proposed. Synthetic aperture sequential beamforming (SASB) is chosen since its computations can be split into two stages, where the output generated of Stage 1 is significantly smaller in size compared to the input. This characteristic enables Stage 1 to be done in the front end while Stage 2 can be sent out to be processed elsewhere. The contributions of this thesis are as follows. First, 2-D SASB is extended to 3-D. Techniques to increase the volume rate of 3-D SASB through a new multi-line firing scheme and use of linear chirp as the excitation waveform, are presented. A new sparse array design that not only reduces the number of active transducers but also avoids the imaging degradation caused by grating lobes, is proposed. A combination of these techniques increases the volume rate of 3-D SASB by 4\texttimes{} without introducing extra computations at the front end. Next, algorithmic techniques to further reduce the Stage 1 computations in the front end are presented. These include reducing the number of distinct apodization coefficients and operating with narrow-bit-width fixed-point data. A 3-D die stacked architecture is designed for the front end. This highly parallel architecture enables the signals received by 961 active transducers to be digitalized, routed by a network-on-chip, and processed in parallel. The processed data are accumulated through a bus-based structure. This architecture is synthesized using TSMC 28 nm technology node and the estimated power consumption of the front end is less than 2 W. Finally, the Stage 2 computations are mapped onto a reconfigurable multi-core architecture, TRANSFORMER, which supports different types of on-chip memory banks and run-time reconfigurable connections between general processing elements and memory banks. The matched filtering step and the beamforming step in Stage 2 are mapped onto TRANSFORMER with different memory configurations. Gem5 simulations show that the private cache mode generates shorter execution time and higher computation efficiency compared to other cache modes. The overall execution time for Stage 2 is 14.73 ms. The average power consumption and the average Giga-operations-per-second/Watt in 14 nm technology node are 0.14 W and 103.84, respectively. / Dissertation/Thesis / Doctoral Dissertation Engineering 2019

This thesis aims to provide a recommended power system design for optimal efficiency, reliability, and cost in off-grid applications. The power system examined in this project is a residence in an off-grid community called Quail Springs that generates its energy from roof mounted solar panels. The existing system was analyzed to see what equipment can remain, what needs to be upsized, and what needs to be added to the system. Two power systems are considered for the residence: a fully AC power system and a hybrid AC/DC power system. Simulations were run in PSCAD to compare the efficiencies of the two proposed systems at varying load. The results of the simulations showed the hybrid power system to be generally less efficient when supplying AC and DC loads, but greater than 5% more efficient when only supplying DC load. Although the hybrid AC/DC system is approximately 70% more expensive, it is still the final recommended design due to potential efficiency gains and in an effort to provide educational opportunities that may lead to further efficiency gains in future hybrid AC/DC power systems.