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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.
151

Missile demonstrator for counter UAV applications

Rydalch, Fletcher D. 06 1900 (has links)
Approved for public release; distribution is unlimited. / An autonomously guided rocket-powered delivery vehicle has been under development at the Naval Postgraduate School. Designed to eventually counter UAV swarm attacks, the vehicle made advances toward reaching a target in the sky. These advances reduced the time needed to launch, modify, and relaunch the rocket, while adding capabilities such as data transfer along the vehicle axis and the rapid download of flight data. Improving the vehicle included reconfiguring the guidance, navigation, and control (GNC) strategy. Advancements included the design, implementation, and evaluation of electronic servo control, actuating fins, and the mechanical coupling design. The forward compartment in the vehicle’s nose cone was structurally modified for the GNC equipment and to support electronics under high-g launch conditions. Modifications included innovative designs for managing heat transfer requirements. Using off-the-shelf subsystem components kept the advancements fiscally mindful. After implementing the design features, two final test launches were performed: one demonstrated a control spin rate of 8.5 rad/sec; the other showed the vehicle’s ability to execute pitch maneuvers on a single axis. The test results can be used to improve the GNC software and servo control parameters. Continued development will allow the system to become a viable option for countering UAV swarms. / Ensign, United States Navy
152

Small camera aerial photography in forest and wildland recreation

Turner, Melvin Howard January 1972 (has links)
This thesis traces the acquisition and potential applications of 35 mm aerial photography as a tool in helping to make decisions in the allocation of land to forest recreation. The advantages of the 35 mm aerial system, including its versatility, simplicity, applicability, and relatively low cost, were tested and applied to the field of forest and wildland recreation. Dealing first with the technology and equipment available, methods of acquiring the imagery were investigated, experimented with, and adopted. Then, working with the results of eleven hours of flying time, photogrammetric and photointerpretive techniques were applied to the reflected attributes of the physiographic, edaphic, hydrologic, and vegetative environments. In addition, the use of the system was investigated for recording recreational use on existing sites. The 35 mm aerial system can help identify those attributes of the land important to forest recreation. In addition it has benefit in the closely related fields of archaeology, protection, and wildlife and in evaluating hazard potential. Used in conjunction with either the small scale imagery soon becoming available through the Earth Resources Technology Satellite Program or existing air photos, the 35 mm system can accurately capture and monitor changes in the natural and artificial environments at a relatively low cost and assist the forest manager in decisions relating to the allocation of forest land to recreational use. / Forestry, Faculty of / Graduate
153

The use of aerial photographs to distinguish between stocking and density of western hemlock stands on the University of British Columbia Research Forest, Haney, B.C.

Chiam, Yeow Chin January 1967 (has links)
Quantitative measures of stand density and stocking are very important because only with full knowledge of the growing stock can a forest be managed efficiently. Stocking is concerned with fraction of area occupied with trees. Density is related to the degree of crowding within the area occupied. These quantitative values are determined by parameters that could be measured on the ground and on aerial photographs. The methods used to estimate height, crown width, and crown closure from aerial photographs are thoroughly described. The writer also describes the stocking and density conditions under which trees grow, with illustrations by both theoretical models and actual sample plot crown models. Forty-seven sets of ground and photo-measurements were taken and analysed by simple and multiple regression methods. A comparison of photo and ground values was then made to evaluate the usefulness of aerial photographs for density and stocking measurements. The correlation of the ratio of height (Ht) to crown width (CW) from the ground and photo data to age, site index, crown closure, basal area, adjusted basal area, crowding factor and adjusted crowding factor were also studied. Eight assumptions regarding normality of density and full stocking were made so that the interrelationship between the individual density and stocking measurements could be studied more effectively. It is concluded that Ht/CW ratios are measurable from aerial photographs and shown that they are useful as a measure of stand density and stocking. / Forestry, Faculty of / Graduate
154

The Proteomic Responses of Gill Tissue in Tidally and Subtidally-Acclimated Mussel Congeners (Mytilus trossulus and Mytilus galloprovincialis) to Acute Aerial-Emersion Hypoxia

Campbell, Jaclyn Denise 01 February 2017 (has links)
Understanding species-specific physiological tolerances to environmental extremes is key in determining the factors that contribute to regulating species distribution. This understanding will aid in determining which species will manage to thrive in a changing global climate. According to the IPCC (2013) it is expected that, in the coming years, many different types of abiotic factors will change as a result of global climate change. The intertidal habitat is a model habitat for studying environmental extremes as it is located at the interface between the marine and terrestrial environments, making it one of the most stressful marine habitats. It is characterized by a 24 hr light: dark cycle and a 12.4 tidal ebb and flow that exposes animals inhabiting this habitat to a wide array of aerial-associated stressors such as changes in temperature, aerial exposure, low oxygen or hypoxic conditions and desiccation stress. Sessile organisms such as marine mussels of the genus Mytilus, are an ideal study species for studying physiological tolerance at the environmental extremes of the intertidal habitat. In particular, M. trossulus and M. galloprovincialis are an excellent study system for examining physiological tolerance at environmental extremes due to the recent change in biogeographic range of both species. M. galloprovincialis, a native of the Mediterranean, has been taking over the coast of California and has been displacing the heat sensitive native M. trossulus. The effects of salinity stress and heat stress on the physiologies of these species have been investigated by Braby and Somero (2006a and 2006b), Tomanek and Zuzow (2010) and Tomanek et al. (2012). The results of these studies indicate that the invasive M. galloprovincialis is more heat tolerant but is sensitive to hyposalinity while the reverse is true for the native M. trossulus.. The next logical environmental stress to study is low tide or aerial-emersion as both species can be found both tidally and subtidally. According to Grieshaber et al. (1994) and Müller et al. (2012) Mytilus edulis mussels have mechanisms for mitigating aerial-emersion hypoxia; however, very few studies have been performed using the study system of M. trossulus and M. galloprovincialis in regard to aerial-emersion hypoxia. This study aimed to observe the responses of both M. trossulus and M. galloprovincialis to aerial-emersion hypoxic stress or low tide. The study also looked to see if the recent habitat history (tidal or subtidal) can play a role in the response of the mussels to hypoxia. The results of the experiment indicate that the invasive M. galloprovincialis may be less sensitive to hypoxic stress when compared to the native M. trossulus. This difference in sensitivity may be due to the difference in mechanisms of energy metabolism proteins and proteostasis proteins used to mitigate the effects of hypoxic stress. Moreover, tidal acclimation appears to better prepare the mussels for subsequent aerial exposure in both species, possibly based upon the principles of stress-hardening outlined by Kültz (2005).
155

Modeling and Analysis of Hybrid Aerial-Terrestrial Networks: A Stochastic Geometry Approach

Alshaikh, Khlod K. 12 1900 (has links)
The ever-increasing demand for better mobile experiences is propelling the research communities to look ahead at how future networks can be geared up to meet such demands. It is likely that the next-generation of wireless communications will be revolutionary, outpacing the current systems capabilities in terms connectivity, reliability and intelligence. These trends and predictions will cause a revolutionary change in the wireless communications. In this context, the concept of Ultra-Dense Network (UDN) is poised to be the cornerstone of the development of fifth generation(5G) systems, whereby a massive number of base stations (BSs) are deployed for enhancing the network performance metrics. Though such densification might be economically viable in urban areas, it is mostly unfavorable in rural ones due to the sheer complexity and the various factors involved the planning and installation processes; all of which trigger the need for cost-effective, flexible and easily-implementable solutions. As a result, unmanned aerial vehicles (UAVs) emerge as a promising alternative solution for enhancing wireless coverage. Due to their mobility capabilities, UAVs are of particular importance in events of (i) terrestrial-based cellular systems dilapidation, (ii) infrastructure absence in remote and suburban areas, or (iii) limited-duration events or activities wherein there is a short-term need for supplementary network resources to handle the overload. While a growing body literature works towards characterizing and providing insights into the performance of UAVs-only networks (serving the first two purposes), understanding the performance of such networks when coupled with existing terrestrial BSs remains a challenging, yet interesting, open research venue. Towards this direction, this thesis provides a rigorous analysis of the downlink coverage probability of hybrid aerial-terrestrial networks using tools from Stochastic Geometry. The thesis presents a mathematical model that characterizes the coverage probability metric under different network environments. The proposed model is validated against intensive simulations so as to substantiate the analytical results. The developed work is essential to understanding the premises of one possible solution to the UDNs of tomorrow, capture its key performance metrics and, most importantly, to uncover key design insights and reveal new directions for the wireless communication industry.
156

Utilization of Canopy Reflectance to Predict Yield Response of Corn and Cotton to Varying Nitrogen Rates

Rattanakaew, Totsanat 11 December 2015 (has links)
Fertilizer N is one of the most costly inputs in corn (Zea mays L.) and cotton (Gossypium hirsutum L.) production and is a strong yield determining factor. Variable rate N fertilization has the potential to improve resource use efficiency, profitability, and help to minimize adverse environmental impacts. Vegetation indices (VIs) may be useful for in-season crop health monitoring to assist in fertilizer N management and yield prediction. This research determined the utility of aerial imagery in detecting corn and cotton response to varying N supply using five selected VIs. The VIs derived from aerial images, chlorophyll readings and tissue N for corn from V5 to V9 growth stages and cotton beginning the 1st week of flowering through to latelowering were used to relate to fertilizer N rates and plant N status and yield. The results showed that VIs derived from aerial imagery could be used to differentiate N supply and in-season grain yield of corn beginning at V5 to V6; however, models from later growth stages had greater r2 values than earlier growth stages. Single variable models that used VI, chlorophyll content, or plant N concentration as an independent variable were overall stronger than 2 variable Multiple Linear Regression models (MLRs). Three independent variables used in MLRs contained multicollinearity. For cotton, the use of VIs derived from aerial imagery to differentiate N supply may depend on environmental factors such as soil and weather. However, VIs may be useful for in-season lint yield prediction beginning the 1st week of flowering although later stages improved accuracy. The MLRs that were developed with 2 independent variables may be more suitable for in-season lint yield prediction than single independent variable models.
157

Potential of Unmanned Aerial Systems Imagery Relative to Landsat 8 Imagery in the Lower Pearl River Basin

Van Horn, John William 09 December 2016 (has links)
Hurricane Isaac’s landfall on the coast of Louisiana spawned a hydrological research project between Mississippi State University (MSU), the Northern Gulf Institute (NGI), and the National Oceanic and Atmospheric Administration (NOAA) in the Lower Pearl River Basin (LPRB). Unmanned aerial systems data collection missions were scheduled every two months in the LPRB. This research provides a comparison between Landsat-8 imagery and corresponding UAS imagery with regards to the four remote sensing resolutions: spatial, spectral, radiometric, and temporal. Near-infrared (NIR) imagery from each platform was compared by land-water masks and statistical comparisons. A classification method known as natural breaks with Jenks Optimization determined threshold values between land and water for each image. Land-water masks revealed substantial differences between areas of land and water in comparing imagery. The overall difference in average land and water percentages between the two platforms was 1.77%; however, a larger percentage was 20.41% in a single comparison.
158

Multispectral/Multitemporal Aerial Detection And Mapping Of Red Imported Fire Ant Colony Mounds In Two Monocultural Grass Types

Carruth, Mark Ellis 30 April 2011 (has links)
The red imported fire ant (Solenopsis invicta)(RIFA) is a major pest in the United States, causing serious economic and human costs. This study explored the feasibility of using digital aerial remote sensing in multispectral/multitemporal detection and mapping of RIFA mounds. Comparison of photointerpretive mound counts versus ground control counts was performed within two grass types, common Bermuda and tall fescue. Flights collecting digital image data occurred at three intervals in 2009, with ground truth data collected collaterally. Poisson regression count modeling was first utilized for analysis of both datasets. Moran's Index geospatial analysis was applied following the Poisson model. Outcomes in this study from these models demonstrate their ability to robustly support studies for tracking and control of RIFA or other pest populations. Additionally, in one location, type of grass cover appeared to affect detectability of mounds between the two methods.
159

Physiography and vegetation of the Albany River map area, northern Ontario : an aerial photography reconnaissance

Dean, William G. January 1959 (has links)
No description available.
160

L’aviation dans la litterature contemporaine. --.

Dwyer, Florence Mary. January 1941 (has links)
No description available.

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