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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.

Optimum bird flock size in formation flight

Kshatriya, Mrigesh January 1990 (has links)
A theoretical model of flock size in migrating birds is developed. Although previous models of formation flight in birds show improved flight performance, they do not explain flock size variation across bird species or at different times of the year for a given bird species. This model captures some of the diversity in flock size observed in nature by incorporating energetic costs of flight and energy income from foraging. It turns out that within a myriad of possible flock sizes there - is one that is optimal for maximizing energetic efficiency (net energetic gain/energy expenditure) for a given maximum range speed, which minimizes flying cost per unit distance flown, and under certain migration conditions (i.e. flight distance and total time to complete the journey). Net energetic gain from foraging equals the rate of prey encountered times the time spent foraging. Energy expenditure from flying is determined from formation flight theory for a fixed wing aircraft. The benefit of formation flight, as derived from an approximation technique, is represented in close-form. This expression is a function of flock size and wing-tip spacing (WTS) and simplifies flight cost calculations. Under certain WTS, a good approximation to the induced drag for a member of a flock of size n is 1/nth of the induced drag of a single bird. In addition, optimum flight speed of a flock is (1/n)⅟₄ of the optimum flight speed of a single individual. The approach taken here allows the prediction of flock size in migrating birds. Model results are discussed in relation to observation of flock size under various migration conditions. If migration is constrained by hours of daylight, seasional variation in flock size is expected if the start time of the north and southward migration are asymmetrical with respect to the summer solstice (June 21). Under certain conditions, such as long non-stop migration, solo flight is an optimum migratory strategy. / Science, Faculty of / Zoology, Department of / Graduate

Brainstem and spinal cord pathways involved in the control of avian locomotion

Weinstein, Gerald Norman January 1984 (has links)
This study examined several aspects of the neural control of locomotion in birds. Initially, it was necessary to define an index of normal locomotor functions. This was accomplished for both flying and walking using electromyographic analysis of forelimb and hindlimb musculature to determine which muscles best define the flight and walking patterns respectively. Secondly, in chronic surviving birds, a series of subtotal spinal lesioning experiments were performed to determine which descending pathways were responsible for the initiation of hindlimb locomotion. Thirdly, results were recorded from brainstem electrical stimulation studies designed to determine the location of locomotor areas in the avian brainstem which effected the initiation and descending control of locomotion in these animals. Results indicated the iliotibialis cranialis (ITC) and flexor cruris lateralis (FCL) muscles best define the swing and stance phases of hindlimb locomotion, respectively. Muscles which best defined the elevator and depressor phases of flying were deltoideus major (DM) and pectoralis (Pect), respectively. Results of the low thoracic selective lesioning experiments support the hypothesis that the medullary reticulospinal pathway is necessary to the initiation and control of volitional hindlimb locomotion. Further, descending input to spinal cord pattern generators via the vestibulospinal pathways may play some adjunctive role or be necessary for the descending control of locomotion. Electrical stimulation of the brainstem in acute decerebrate birds elicited locomotor behaviours in both hindlimbs and forelimbs. Four areas, including; an area near the lateral /medial spiriform nucleus; nucleus et tractus descendens trigemini; and central nucleus of the medulla, pars ventralis and dorsalis; and the lateral reticular nucleus produced varying locomotor behaviours when stimulated. Acute dorsal cord transection did not affect the electrically stimulated behaviour, indicating that descending pathways from supraspinal centres which travel in the dorsal cord do not affect the descending control of locomotion. A strong parallel exists between the results of this study in two avian species and those found in the mammalian literature. / Science, Faculty of / Zoology, Department of / Graduate

Parametric Paraglider Modeling

Heatwole, Peter F. 01 March 2022 (has links) (PDF)
Dynamic simulations are invaluable for studying system behavior, developing control models, and running statistical analyses. For example, paraglider flight simulations could be used to analyze how a wing behaves when it encounters wind shear, or to reconstruct the wind field that was present during a flight. Unfortunately, creating dynamics models for commercial paraglider wings is difficult: not only are detailed specifications unavailable, but even if they were, a detailed model would be laborious to create. To address that difficulty, this project develops a paraglider flight dynamics model that uses parametric components to model commercial paraglider wings given only limited technical specifications and knowledge of typical wing design. To validate the model design and implementation, an aerodynamic simulation of a reference paraglider canopy is compared to wind tunnel measurements, and a dynamic simulation of a commercial paraglider system is compared to basic flight test data. The entirety of the models and example wings are available as an open source library built on the Python scientific computing stack.

An evaluation of the utility of a Personal Computer-based Aviation Training Device (PCATD) for private pilot's licence training

Dennis, K. A. January 1997 (has links)
No description available.

A study on the potential cost savings associated with implementing airline pilot training curricula into the future P-8 MMA fleet replacement squadron

Vignola, Jay S. 06 1900 (has links)
This thesis discusses potential cost savings associated with implementing airline pilot training curricula into the future P-8 Multimission Maritime Aircraft (MMA) Fleet Replacement Squadron (FRS). These curricula rely primarily on high-technology flight simulators and do not require any flight time in an actual aircraft. This thesis also provides an approach for estimating future P-8 FRS cost savings. The results of this thesis indicate that significant savings will likely accrue in the areas of fuel, Aviation Depot Level Repairables (AVDLR) and training expendable stores costs if airline pilot training curricula are implemented into the P-8 FRS in FY 2014. Further research is needed in many other cost areas before additional cost savings estimations can be made. Finally, this thesis discusses many additional considerations that should be taken into account before a future airline pilot training curricula implementation decision is made.

Development, modeling, and simulation of a nano aerial vehicle using empirical data

Davenport, Wyatt Emery, January 2007 (has links) (PDF)
Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed January 28, 2008) Includes bibliographical references (p. 83-84).

Linearised optimal control and application to a gliding projectile /

Jepps, G. January 1980 (has links) (PDF)
Thesis (M.Eng.Sc.) - Dept. of Electrical and Electronic Engineering, University of Adelaide, 1983. / AR-003-687. Originally his Thesis (M.Eng.Sc.) - Dept. of Electrical and Electronic Engineering, University of Adelaide, 1980. Photostat. Includes bibliographical references (p. 66-67).

Systems and human factors concerns for long-duration spaceflight /

Holland, Dwight A. January 1991 (has links)
Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1991. / Vita. Abstract. Includes bibliographical references (leaves 117-125). Also available via the Internet.

Development of a variable stability flight simulation facility re-engineering of flight control loading and motion systems /

Scamps, Alexander. January 2003 (has links)
Thesis (M.E. (Res.))--University of Sydney, 2003. / Title from title screen (viewed Apr. 28, 2008). Submitted in fulfilment of the requirements for the degree of Master of Engineering (Research) to the School of Aerospace, Mechanical and Mechatronic Engineering. Includes bibliography. Also available in print form.

SAA cabin attendant's [sic] experience of environmental stressors

Henning, Sanchen. January 2005 (has links)
Thesis (M.A.(Research Psychology))--University of Pretoria, 2001. / Includes bibliographical references.

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