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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Ship Detection and Property Extraction in Radar Images on Hardware

Kilinc, Koray 21 August 2015 (has links)
In this work we review the problem of radar imaging satellites' dependency on ground stations to transfer the image data. Since synthetic aperture radar images are very big, only ground stations are equipped to transfer that much data. This is a problem for maritime surveillance as it creates delay between the imaging and processing. We propose a new hardware algorithm that can be used by a satellite to detect ships and extract information about them, and since this information is smaller it can be relayed to reduce the delay significantly. For ship detection, an adaptive thresholding algorithm with exponential model is used. This algorithm was selected as it is the best fit for single-look radar images. For the property calculation, a data accumulating, single-look, connected component labeling algorithm is proposed. This algorithm accumulates data about the connected components, which is then used to calculate the properties of ships using image moments. The combined algorithm was then validated on Radarsat-2 images using Matlab for software and co-simulation for hardware. / Graduate
212

LOW COST ULTRA WIDEBANDRADAR FOR HUMAN PROTECTION

Hampus, Carlsson, Martina, Öhlund January 2015 (has links)
The majority of the UWB radars available on the market today are expensive and often closed forfurther development due to proprietary rights. Therefore it is difficult to fully understand and adaptthe functionality of an available UWB system to fit one’s needs. The consulting-firm Addiva purchasedan UWB radar to be used in a safety system. However, the radar had limitations and the functionalityof it was partly unknown. This master thesis was inspired from this issue to examine the possibilitiesof developing a low-cost UWB radar, with main focus on research of human detection. The systemshould be easy to understand and modify, as well as reporting reliable data from the scanning. Theresults indicate that such a system can be developed. However, further development to the UWB radarneeds to be made in order to have a complete system.
213

Thermo-economic optimization of a heat recovery steam generator (HRSG) system using Tabu search

Liu, Zelong 11 November 2010 (has links)
Heat Recovery Steam Generator (HRSG) systems in conjunction with a primary gas turbine and a secondary steam turbine can provide advanced modern power generation with high thermal efficiency at low cost. To achieve such low cost efficiencies, near optimal settings of parameters of the HRSG must be employed. Unfortunately, current approaches to obtaining such parameter settings are very limited. The published literature associated with the Tabu Search (TS) metaheuristic has shown conclusively that it is a powerful methodology for the solution of very challenging large practical combinatorial optimization problems. This report documents a hybrid TS-direct pattern search (TS-DPS) approach and applied to the thermoeconomic optimization of a three pressure level HRSG system. To the best of our knowledge, this algorithm is the first to be developed that is capable of successfully solving a practical HRSG system. A requirement of the TS-DPS technique was the creation of a robust simulation module to evaluate the associated extremely complex 19 variable objective function. The simulation module was specially constructed to allow the evaluation of infeasible solutions, a highly preferable capability for methods like TS-DPS. The direct pattern search context is explicitly embodied within the TS neighborhoods permitting different neighborhood structures to be tested and compared. Advanced TS is used to control the associated continuum discretization with minimal memory requirements. Our computational studies show that TS is a very effective method for solving this HRSG optimization problem. / text
214

Development of a meso-scale liquid-fueled burner for electricity generation through the use of thermoelectric modules

Rechen, Ross Michael 12 July 2011 (has links)
The goal of this research was to design, build and test a small burner and heat exchanger system that could be used as a source of heat for thermoelectric modules (TEMs) for the purpose of generating portable electric power for soldiers in the field. The project was conducted as a subcontract to Marlow Industries Inc. which was under contract from the U.S. Army. The scale of the burner thermal output was to be in the approximate range of 2 kW of heat production and it was to be able to operate on a liquid fuel, specifically JP8. The first burner investigated was a custom burner designed and built at UT. It was tested with various fuel and air delivery systems. Different methods to start it, with the goal of developing an electrical starting system, were also investigated. It was capable of operating at outputs over 1 kW, but was difficult to start reliably and fuel vaporization characteristics were sensitive to operating conditions. Two commercial burners were also studied, each with somewhat different designs. One of those burners, manufactured by MSR, was chosen to be further tested in conjunction with a heat exchanger and thermoelectric modules. The performance of the thermoelectric modules used in this study was determined to be very dependent on an attached resistive load, with a peak power output occurring at approximately 3 ohms. Power output was also determined to increase linearly with increasing temperature difference between the hot and cold sides of the module. Power output followed similar trends as open circuit voltage. The temperatures of the heat exchanger across its width were very uniform, but the accuracy in centering the heat exchanger over the burner could significantly affect temperatures. The time to reach steady state temperatures was relatively insensitive to the length of the heat exchanger. The presence of attached thermoelectric modules reduced the temperature of the heat exchangers and exhaust gas slightly. Reducing the heat exchanger length resulted in higher metal temperatures. Without cooling the cold side of the thermoelectric modules, performance increased while the system was heating up, but then dropped after reaching a peak. Cold side cooling improved thermoelectric performance by increasing its temperature difference. Active cooling with a blower and heat sink provided even better performance than passive cooling using just a heat sink at the expense of a larger parasitic load. The TEMs on the 5 inch long heat exchanger could generate 6.32 W with passive cooling, but active cooling would produce no net power. The 11 inch long heat exchanger could generate 12.8 W with passive cooling, and 16 W net could be generated with active cooling. A heat exchanger efficiency calculation showed that the 16, 11 and 5 inch long heat exchangers were about 94.4%, 93.4%, and 90.7% efficient respectively. This efficiency was defined as the ratio of the heat transferred to the heat exchanger to the heat released in the flame. / text
215

Various statistical test of pseudorandom number generator

Haque, Mohammad Shafiqul January 2010 (has links)
This thesis is related to varies statistical test of pseudorandom number generator. In thisthesis I have tried to discuss some aspects of selecting and testing Pseudorandom numbergenerators. The outputs of such generators may be used in many cryptographic applications,such as the generation of key material. After statistical test I have tried to compairethe test value of every generator and have discussed which one is producing good sequencesand which one is a good generator.
216

Generic Wind Turbine Generator Model Comparison Based on Optimal Parameter Fitting

Dai, Zhen 18 March 2014 (has links)
Parameter tting will facilitate model validation of the generic dynamic model for type-3 WTGs. In this thesis, a test system including a single 1.5 MW DFIG has been built and tested in the PSCAD/EMTDC environment for dynamic responses. The data generated during these tests have been used as measurements for the parameter tting which is carried out using the unscented Kalman lter. Two variations of the generic type-3 WTG model (the detailed model and the simpli ed model) have been compared and used for parameter estimation. The detailed model is able to capture the dynamics caused by the converter and thus has been used for parameter tting when inputs are from a fault scenario. On the other hand, the simpli ed model works well for parameter tting when a wind speed disturbance is of interest. Given measurements from PSCAD, the estimated parameters using both models are indeed improvements compared to the original belief of the parameters in terms of prediction error.
217

Generic Wind Turbine Generator Model Comparison Based on Optimal Parameter Fitting

Dai, Zhen 18 March 2014 (has links)
Parameter tting will facilitate model validation of the generic dynamic model for type-3 WTGs. In this thesis, a test system including a single 1.5 MW DFIG has been built and tested in the PSCAD/EMTDC environment for dynamic responses. The data generated during these tests have been used as measurements for the parameter tting which is carried out using the unscented Kalman lter. Two variations of the generic type-3 WTG model (the detailed model and the simpli ed model) have been compared and used for parameter estimation. The detailed model is able to capture the dynamics caused by the converter and thus has been used for parameter tting when inputs are from a fault scenario. On the other hand, the simpli ed model works well for parameter tting when a wind speed disturbance is of interest. Given measurements from PSCAD, the estimated parameters using both models are indeed improvements compared to the original belief of the parameters in terms of prediction error.
218

Negative sequence impedance measurement for distributed generator islanding detection

Wrinch, Michael C. 05 1900 (has links)
This thesis presents a method of detecting electrical islands in low voltage distributed generator networks by measuring negative sequence impedance differences between islanded and utility connections. Extensive testing was conducted on a commercial building and 25 kV distributed generator fed network by measuring naturally occurring and artificially injected negative sequence components. Similarly, this technique was tested using the IEEE 399-1990 bus test case using the EMTP software. The practical measurements have been matched to simulations where further system performance characteristics of detecting power system islands has been successfully demonstrated. Measured results indicate that unbalanced load conditions are naturally occurring and readily measurable while deliberately unbalanced loads can increase the accuracy of negative sequence impedance islanding detection. The typically low negative sequence impedance of induction motors was found to have only a small effect in low voltage busses, though large machines can effect the threshold settings. Careful placement of the island detector is required in these situations. The negative sequence impedance measurement method is an improvement on previous impedance measurement techniques for islanding detection due to its accuracy, and distinctly large threshold window which have challenged previous impedance based islanding detection techniques.
219

Cellular mechanisms involved in stress-induced coma and CNS spreading depression in the locust.

Rodgers, Corinne Ivy 06 August 2010 (has links)
Spreading depression (SD) is an interesting and important phenomenon due to its role in mammalian pathologies such as migraine, seizures, and stroke. Until recently investigations of the mechanisms involved in SD have mostly utilized mammalian cortical tissue, however in my thesis I demonstrated that SD-like events occur in the CNS of an invertebrate model, Locusta migratoria. Locusts enter comas in response to stress during which neural and muscular systems shut down until the stress is removed, and this is believed to be an adaptive strategy to survive extreme environmental conditions. Using the ventilatory central pattern generator (vCPG) as a model circuit I was able to show that stress-induced arrest of vCPG function is associated with SD-like events in the locust metathoracic ganglion (MTG) that closely resemble cortical SD (CSD) in many respects, including mechanism of induction, extracellular potassium ion ([K+]o) changes, and propagation in areas equivalent to mammalian grey matter. SD-like events in the locust were characterized as abrupt [K+]o increases associated with electrical activity silence in the locust CNS that propagate to other areas within the MTG. In this thesis I described the generation of comas by several cellular stressors (hyperthermia, metabolic stressors, Na+/K+-ATPase inhibition, and KCl) and the associated SD-like events in the locust, provide a description of the similarities to CSD, and show how they can be manipulated both by stress preconditioning and pharmacologically. I showed that hyperthermic vCPG arrest can be preconditioned by prior heat shock (HS) treatment and induced-thermotolerance was associated with an increased rate of [K+]o clearance associated with vCPG recovery that was not linked to changes in ATP levels or total Na+/K+-ATPase activity. I also provided evidence for the involvement of the stress-sensor AMP-activated protein kinase (AMPK) in stress-induced comas in the locust. AMPK activation was linked to a switch in motor pattern behavior following recovery from anoxia-induced vCPG arrest and exacerbated repetitive SD-like events induced by ouabain (Na+/K+-ATPase inhibitor). I suggested that locust SD-like events are adaptive by conserving energy and preventing cellular damage, and I provided a model for the mechanism of SD onset and recovery in the locust nervous system. / Thesis (Ph.D, Biology) -- Queen's University, 2010-08-05 16:08:19.905
220

Movement Generator For Mobile Network Simulation

Alghamdi, Raid Abdullah 11 January 2012 (has links)
The simulation of mobile networks relies on a reliable movement generation. Random movement patterns are frequently used in simulators. In this report, the performance of the popular setdest movement generator, which is built into the ns2 open source simulator, is investigated using two statistical tests: quadrat count test and the variance to mean ratio (VMR) test. The results show a non-uniform distribution of nodes during the simulation with a bias towards placing the nodes in the center of the simulated area. We propose and implement a di erent method for random movement generation in the ns2 simulator and show that our movement generator improves the randomness of the node distribution during the simulation. The new generator was successfully tested with the ns2 simulator.

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