Swarm keeping strategies for spacecraft under J2 and atmospheric drag perturbations

This thesis presents several new open-loop guidance methods for spacecraft swarms comprised of hundreds to thousands of agents with each spacecraft having modest capabilities. These methods have three main goals: preventing relative drift of the swarm, preventing collisions within the swarm, and minimizing the fuel used throughout the mission. The development of these methods progresses by eliminating drift using the Hill-Clohessy-Wiltshire equations, removing drift due to nonlinearity, and minimizing the $J_2$ drift. In order to verify these guidance methods, a new dynamic model for the relative motion of spacecraft is developed. These dynamics are exact and include the two main disturbances for spacecraft in Low Earth Orbit (LEO), $J_2$ and atmospheric drag. Using this dynamic model, numerical simulations are provided at each step to show the effectiveness of each method and to see where improvements can be made. The main result is a set of initial conditions for each spacecraft in the swarm which provides hundreds of collision-free orbits in the presence of $J_2$. Finally, a multi-burn strategy is developed in order to provide hundreds of collision free orbits under the influence of atmospheric drag. This last method works by enforcing the initial conditions multiple times throughout the mission thereby providing collision free motion for the duration of the mission

Extraction and Classification of Diving Clips from Continuous Video Footage

Due to recent advances in technology, the recording and analysis of video data has become an increasingly common component of athlete training programmes. Today it is incredibly easy and affordable to set up a fixed camera and record athletes in a wide range of sports, such as diving, gymnastics, golf, tennis, etc. However, the manual analysis of the obtained footage is a time-consuming task which involves isolating actions of interest and categorizing them using domain-specific knowledge. In order to automate this kind of task, three challenging sub-problems are often encountered: 1) temporally cropping events/actions of interest from continuous video; 2) tracking the object of interest; and 3) classifying the events/actions of interest. Most previous work has focused on solving just one of the above sub-problems in isolation. In contrast, this paper provides a complete solution to the overall action monitoring task in the context of a challenging real-world exemplar. Specifically, we address the problem of diving classification. This is a challenging problem since the person (diver) of interest typically occupies fewer than 1% of the pixels in each frame. The model is required to learn the temporal boundaries of a dive, even though other divers and bystanders may be in view. Finally, the model must be sensitive to subtle changes in body pose over a large number of frames to determine the classification code. We provide effective solutions to each of the sub-problems which combine to provide a highly functional solution to the task as a whole. The techniques proposed can be easily generalized to video footage recorded from other sports.Comment: To appear at CVsports 201

Caldolysin, a highly active protease from an extremely Thermophilic Bacterium

Proteases comprise a significant proportion of those proteins which have been subject to detailed characterisation (amino acid sequence and high resolution crystallographic analysis). The extent of research interest in proteolytic enzymes reflects both their historical status, and the practical advantages of proteases as research subjects (available in quantity, extracellular etc.) widely occurring

The industrial potential of enzymes from extremely thermophilic bacteria

The thermal regions of the central North Island of New Zealand are some of the most extensive in the world. In addition, they are readily accessible and contain a diversity of ecological habitats, including a large number at 100°C. These areas are regarded as an important tourist attraction, and as a source of geothermal power, It is now clear that they also contain an important and unique genetic resource

Feasibility Study of Solar Canopy Structure on Exchange Parking Deck

This project examines the feasibility of installing a solar panel array to the top deck of the Exchange Parking deck via canopy structure. Installation of solar panels would provide potential environmental and financial benefits to The University of Akron. Available solar panels analyzed were limited to two types, monocrystalline and polycrystalline, based on the properties of each panel. The pool of available panels was then narrowed to the 10 most promising panels based on power generated and cost. The most cost efficient panel was then chosen based on projected cost savings over a 25-year period, based on guaranteed performance warranty given for each panel. A canopy system was then designed to support the weight of the panels. The cost savings over the 25-year lifespan of best available panel was found to be $1,163,000, but the cost of the canopy support structure and solar panel material was found to be$2,673,000. This leads to a cost deficiency of $1,510,000 over the 25-year performance warranty period for the panels and a payback period of 60 years. Given the risks associated with a payback period 45 years beyond the warranty period, it is therefore recommended that a solar panel array is not constructed on the Exchange Parking Deck at this time. Once newer technologies with better power conversion efficiencies are available for purchase, a new study should be done to determine feasibility of installation

Evaluation of Groundwater Sodium and Sodium Uptake in Taxodium and its Hybrids on Galveston Island, Texas

In September 2008, Hurricane Ike swept through the Gulf of Mexico striking the Gulf Coast, claiming hundreds of lives and causing billions of dollars in damage. The hurricane left behind elevated sea salt concentrations in the soil and groundwater, preventing the unaided return of live oaks and other species to the island. To determine effective ways to ameliorate the elevated Na+ concentrations in the soil, eight treatments were applied to the soil and combinations of three species of plants, live oak (Quercus virginiana), hybrid bald cypress (Taxodium ‘T406’), and yellow hibiscus (Hibiscus hamabo) were planted in the plots. These plants were measured for growth in height and diameter over three growing seasons to evaluate the effectiveness of the applied treatments. The Taxodium ‘T406’ specimens were then sampled in order to determine elemental concentrations in the foliage across applied treatments. In addition, foliage samples were taken from a series of Taxodium genotypes in order to compare Na+ tolerance among the genotypes. In order to evaluate the groundwater characteristics of the study area a three by three grid of piezometers, spaced 25 m apart north by south and 60 m apart east by west, was established and groundwater samples were collected from September 2018 to September 2019. Three Solinst Leveloggers were used in the easternmost piezometers in order to provide a continuous stream of data for each piezometer. Groundwater Na+ concentrations were compared with precipitation data to determine if precipitation has a significant impact on elemental concentrations. Plant diameter growth was not significant for diameter among species or treatments, and height growth was also not significant among treatments. Taxodium distichum displayed significantly greater height growth than the other species, possibly due to damage to the other species early in the study. Na+ concentrations did not differ significantly among treatments, although among the genotypes there was a significantly higher concentration of Na+ in the Taxodium ‘T406’ compared to Taxodium distichum. A significant relationship could not be determined between groundwater Na+ concentrations and precipitation