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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.
71

Tranų (apis mellifera l.) skraidymo ritmai / Rythm of drone (apis mellifera l.) flying

Katinienė, Aurelija 16 August 2007 (has links)
2004 ir 2006 m. birželio – rugpjūčio mėn. buvo tiriama medunešių bičių (Apis mellifera L.) tranų skraidymo pradžia, tranų skraidymo dinamika dienos metu ir kokią įtaką jai daro aplinkos temperatūra. Įvertintas išskrendančių ir atskrendančių į tą pačią bičių šeimą tranų skaičius bei tranų skridimas į svetimas bi��ių šeimas. Ištirta 6 stipresnės ir 5 silpnesnės bičių šeimos. Buvo skaičiuojami per 2 min. iš avilio išskridę, po to per 2 min. į avilį atskridę tranai. Kiekvienos bičių šeimos tranai buvo pažymėti skirtinga spalva. Žymėti tranai turėjo savo individualius numerius. Tyrimų rezultatai parodė, tranai pradeda skraidyti 5 parų amžiaus. Tranų skraidymas dieną prasideda nuo 12 val., o baigiasi 18 val. Jų išskridimas iš bičių šeimų pasiekia maksimumą apie 15 val., o sugrįžimas po skraidymo – apie 17 val. Esant daugiau nei 25ºC šilumos tranų skridimas iš šeimų pasiekia maksimumą apie 15 – 16 val., o sugrįžimas į jas – apie 17val. Kiekvienoje bičių šeimoje yra pusiausvyra tarp išskrendančių ir atskrendančių į ją tranų skaičiaus. Po skraidymo sugrįžtantys į bičių šeimą tranai yra dviejų rūšių: pasirenkantys tik savo šeimą ir pasirenkantys ne tik savo, bet ir kitas bičių šeimas (daugiau nei vieną šeimą). / During 2004 and 2006 June – August research was made to ascertain honeybees (Apis mellifera L.) drones starting to fly, their flying dynamic during the day and how it depends on surroundings temperature. Were counted numbers of drones flying in and out the same honeybees colonies and number of drones flying to the other honeybees colonies. For research were taken 6 stronger and 5 weaker honeybees colonies. Were counted number of drones flying out of the hive in 2 minutes period, after - were counted number flying in drones for the same period. Each colony drones were marked in different color and every marked drone had individual number. Researches showed that drones start to fly at the age of 5 days. During the day they begin to fly from 12 p.m. and stop flying at around 6 p.m. Highest number of drones flying out of hive is around 3 p.m., flying in - around 5 p.m. Each honeybees colony keeps balance between flying in and out of hive drones. Here are two kinds of drones, returning back to honeybees colony after flying: the ones, who choose only their own colony, and the others, that choose not only own colony, but others too (more than one colony).
72

Modeling, Simulation and Control System Design for Civil Unmanned Aerial Vehicle (UAV)

Bagheri, Shahriar January 2014 (has links)
Unmanned aerial systems have been widely used for variety of civilian applications over the past few years. Some of these applications require accurate guidance and control. Consequently, Unmanned Aerial Vehicle (UAV) guidance and control attracted many researchers in both control theory and aerospace engineering. Flying wings, as a particular type of UAV, are considered to have one of the most efficient aerodynamic structures. It is however difficult to design robust controller for such systems. This is due to the fact that flying wings are highly sensitive to control inputs. The focus of this thesis is on modeling and control design for a UAV system. The platform understudy is a flying wing developed by SmartPlanes Co. located in Skellefteå, Sweden. This UAV is particularly used for topological mapping and aerial photography. The novel approach suggested in this thesis is to use two controllers in sequence. More precisely, Linear Quadratic Regulator (LQR) is suggested to provide robust stability, and Proportional, Integral, Derivative (PID) controller is suggested to provide reference signal regulation. The idea behind this approach is that with LQR in the loop, the system becomes more stable and less sensitive to control signals. Thus, PID controller has an easier task to do, and is only used to provide the required transient response. The closed-loop system containing the developed controller and a UAV non-linear dynamic model was simulated in Simulink. Simulated controller was then tested for stability and robustness with respect to some parametric uncertainty. Obtained results revealed that the LQR successfully managed to provide robust stability, and PID provided reference signal regulation.
73

Reconfiguration and Recovery of Formation Flying Spacecraft in Eccentric Orbits

Roscoe, Christopher William Thomas 22 September 2009 (has links)
The problem of reference trajectory reconfiguration and long-term uncontrolled recovery of a formation of spacecraft is considered in an eccentric orbit under the influence of the J2 perturbation. Reference trajectories considered are the Projected Circular Orbit, Along-Track Orbit, and their eccentric modifications. Reconfiguration is accomplished using two, finite-pulse thrusts, modeled as impulses. The state transition matrix (STM) is calculated by four methods: (i) analytically from the Hill-Clohessy-Wiltshire equations, (ii) numerical integration using a fourth-order Runge-Kutta method, (iii) from the fundamental matrix of the linearized equations of motion, and (iv) computing the STM for the relative mean orbital elements, the geometric method. Only the geometric method takes into account J2, and it is shown to perform the transfers most accurately of all the methods. The methods are also applied to the reconfiguration maneuvers of the University of Toronto's CanX 4/5 formation flying mission.
74

Reconfiguration and Recovery of Formation Flying Spacecraft in Eccentric Orbits

Roscoe, Christopher William Thomas 22 September 2009 (has links)
The problem of reference trajectory reconfiguration and long-term uncontrolled recovery of a formation of spacecraft is considered in an eccentric orbit under the influence of the J2 perturbation. Reference trajectories considered are the Projected Circular Orbit, Along-Track Orbit, and their eccentric modifications. Reconfiguration is accomplished using two, finite-pulse thrusts, modeled as impulses. The state transition matrix (STM) is calculated by four methods: (i) analytically from the Hill-Clohessy-Wiltshire equations, (ii) numerical integration using a fourth-order Runge-Kutta method, (iii) from the fundamental matrix of the linearized equations of motion, and (iv) computing the STM for the relative mean orbital elements, the geometric method. Only the geometric method takes into account J2, and it is shown to perform the transfers most accurately of all the methods. The methods are also applied to the reconfiguration maneuvers of the University of Toronto's CanX 4/5 formation flying mission.
75

Are we ready to drive to the sky? personal air- land vehicles within the modern air law framework and Theory of Legal Innovation /

Burchevskyy, Oleksiy. January 1900 (has links)
Thesis (LL.M.). / Written for the Faculty of Law. Title from title page of PDF (viewed 2009/06/17). Includes bibliographical references.
76

An examination of two unconventional methods to assess resource use by two New Brunswick forest mammals : the marten and the northern flying squirrel

Bourgeois, Maryse C. January 1900 (has links) (PDF)
Thesis (M. Sc.)--Acadia University, 1997. / Includes bibliographical references. Also available on the Internet via the World Wide Web.
77

An examination of two unconventional methods to assess resource use by two New Brunswick forest mammals : the marten and the northern flying squirrel /

Bourgeois, Maryse C. January 1900 (has links) (PDF)
Thesis (M. Sc.)--Acadia University, 1997. / Includes bibliographical references. Also available on the Internet via the World Wide Web.
78

The flight of the ordinary narrative, poetics, power and UFOs in the American uncanny /

Lepselter, Susan Claudia, Stewart, Kathleen, January 2005 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Kathleen Stewart. Vita. Includes bibliographical references.
79

Public Perception of Autonomous Aircraft

January 2018 (has links)
abstract: The aviation industry is considered to be the safest when it comes to transportation of people and property. The standards by which companies provide air transportation are held are very high. Nevertheless, a shortage in the number of pilots exists and companies must look for ways to meet demands. One of the ways to resolve this issue is to introduce unmanned systems on a broader scale – to transport people and property. The public’s perception regarding this issue has not been well documented. This survey identified what the public’s attitude is towards the use of these systems. One hundred fifty-seven people participated in this survey. Statistical analyses were conducted to determine if participant demographics, previous aviation background, and comfort levels were significantly related to various transportation technologies. Those who were comfortable or uncomfortable with self-driving cars kept their same comfort level for other technologies such as drone delivery services. The survey also revealed that the vast majority of respondents did not feel comfortable being a passenger on fully autonomous aircraft. With an overwhelming percentage of society not comfortable with the idea of there being no pilot for the aircraft, it is important for companies working to implement this technology to pay close attention to the public perception of autonomous aircraft. / Dissertation/Thesis / Masters Thesis Technology 2018
80

Anxiété de vol et phobie de l'avion : validation de questionnaires d'auto-évaluation et étude des comportements des passagers / Flight anxiety and flight phobia : validation of self-report measures and study of passenger behavior

Bourgoin, Émilie 07 September 2015 (has links)
La peur de l’avion peut être source de grande souffrance chez les passagers anxieux qui représentent 10 à 40% de la population. Dans certains cas, elle peut aboutir au développement d’une phobie de l’avion. Peu d’études ont permis de développer des outils de mesure évaluant l’anxiété liée au vol en avion; et encore moins, ont cherché à mettre en évidence les comportements anxieux lors de vol en avion. L’objectif de ce travail était de valider des outils d’évaluation de l’anxiété de vol en français, et d’améliorer la compréhension de la dimension comportementale de ce trouble. Cinq études ont été menées. La première propose la traduction et la validation de deux questionnaires évaluant l’anxiété de vol : le Flight Anxiety Situation questionnaire (FAS) et le Flight Anxiety Modality questionnaire (FAM). Les résultats démontrent de bonnes qualités psychométriques des deux questionnaires dans leur version française. Les quatre autres études visaient à construire un questionnaire d’évaluation des comportements anxieux autour du vol en avion et à mettre en évidence les comportements chez des patients phobiques de l’avion. Les résultats indiquaient une validité partiellement satisfaisante ; des comportements d’hyper-vigilance, d’anticipation, de consommation de substance, de recherche de soutien social, de recherche d’information et de contrôle, et des comportements de gestion pro-active centrée sur soi ont été mis en évidence. Parmi les individus phobiques de l’avion, les individus présentant un trouble agoraphobique ou un trouble d’anxiété généralisé adoptaient des comportements spécifiques. De futures études sont proposées pour poursuivre sa validation. / The literature suggests that fear of flying affects 10-40% of the population and can represent a significant source of anxiety for airline passengers. In some cases flying phobia can develop. Few studies have developed measures that adequately assess anxiety linked to flying; moreover, to our knowledge there is very little research on the behavioral manifestations linked to fear of flying. The research carried out for this thesis seeks to validate French translations of existing flying anxiety measures as well as develop tools for evaluating behavioral manifestations linked to fear of flying. Five studies has been conduct. The main objective of the first study was to translate and validate two existing flying anxiety scales: the Flight Anxiety Situation questionnaire (FAS) and the Flight Anxiety Modality questionnaire (FAM) created by Van Gerwen et al. (1999). The results demonstrated good psychometric validity for the French versions of these two questionnaires. The four other studies were orientated at the creation of a scale (Questionnaire des Comportements anxieux autour du Vol Aérien; QCVA) measuring behaviors associated with anxiety and flying and to evaluate the validity of such a measure. The results demonstrated partial validity; behaviors were clearly delineated into categories of hypervigilance, anticipation, substance consumption, social support seeking, information seeking/situational control, and proactive behaviors centered on the individual. Within the phobic group, those who also suffered from agoraphobia or generalized anxiety disorder furthermore adopted specific behavior. Additional studies are suggested to further explore the revealed factors.

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