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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.
81

Systematic Study of Flying Squirrels (Mammalia, Sciuridae) in Lao PDR / ラオス産滑空性リス類(哺乳綱リス科)の分類学的研究

Daosavanh, SANAMXAY 23 March 2020 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第13320号 / 論理博第1567号 / 新制||理||1663(附属図書館) / (主査)教授 本川 雅治, 准教授 中野 隆文, 教授 曽田 貞滋 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DFAM
82

Design letecké přilby pro otevřené létání / Design of Freeflight Helmet

Dvořák, František January 2020 (has links)
This diploma thesis describes a redesign process of a flight helmet designated to open air flying. The design solution of this sophisticated equipment focuses primarily on safety, low total weight, excellent ergonomics and the best possible sound insulation. In this case, two-way radio communication and mobile phone connectivity are also very important aspects of the final product. The task is based on real demands of the Czech paramotors and aircraft equipment producer - Nirvana Systems s.r.o. Therefore this thesis doesn’t deal only with the aesthetic appearance of the new flight helmet, but it also fully reflects all technical, production and economic aspects.
83

Parametric Studies on UAV Flying Qualities

Lesiário, Ana January 2009 (has links)
When developing an aircraft, one of several important aspects is to predict and properly design the dynamic behaviour of the aircraft. This holds for manned aircraft as well as for UAVs. The optimal dynamic behaviour for an aircraft depends on the mission or purpose: for a certain use an aircraft should be agile, other may require a more stable one. In aeronautics, the properties that describe the aircraft ecacy with respect to some task are known as ying qualities, and our goal is to study their dependence on some design parameters. As a test model we use an existing UAV. After deriving its 6-DOF dynamic model and assessing its baseline characteristics, we perform parametric studies. The strategy followed is divided in two steps: the rst consists on analyzing ying qualities sensitivity to changes in model parameters. The second step studies how specific design changes affect model parameters. Because the rst step only depends on the dynamic model form, we verify, by testing two other dierent aircrafts, that conclusions drawn from this step are valid to other congurations. Finally we show how results from parametric studies can be used to improve the UAV ying qualities regarding a certain mission, through the introduction of slight modications on baseline design.
84

A Vision-Based Distance Estimation System for Flying Copters

Li, Zetong 16 September 2020 (has links)
Currently, as one of the most popular technologies being discussed and experimented, the application of flying copters in different industries is facing an obvious barrier; which is how to avoid obstacles while flying. One of the industries among all is small-sized package delivery business, which is also the master topic of a series of experiments. The most popular designs that have used for the Flying Copter Obstacle Avoidance System such as lidar scanners and infrared rangefinders are significantly accurate. However, with the heavyweight, expensive price and higher power consumption, these systems cannot be put into mass production. To reduce the cost and power consumption of the Obstacle Avoidance System, an innovative vision-based low-cost Obstacle Distance Estimation System for flying copters is demonstrated in this thesis. The Fisheye Lens Camera is used to provide a broader detection range and accurate results. Compared to other standard vision-based systems, the Fish Lens Camera Distance Estimation System can provide (around 360 degrees) extensive view for obstacle detection. Through the parallax pictures captured by the camera and the trigonometric rules, the system can estimate the distance to the target obstacle with reasonable results.
85

Albedo of the Earth's Surface -- A Comparison of Measurements Taken on the Ground and from Flying Platforms

Eaton, Frank D. 01 May 1976 (has links)
The main objectives of this study were to develop the indicatri es of reflected solar radiation from different natural surfaces and to show comparisons between values sensed in space of emergent radiation to ground values obtained from accounting for anisotropic reflection and estimating the effect of the intervening atmosphere. Thus, this study demonstrated that a prior knowledge of the angular distribution of reflected radiation allows determining the true hemispherical reflected radiation from a narrow field of view instrument such as found on a flying platform. Measurements for determining the indicatrices were made from a tower-mounted Nimbus MRIR and, in one case, with a hand-held TIROS five-channel radiometer. Anisotropy of reflected radiation was found for all surfaces examined and increased with decreasing solar angle. Different surfaces showed different degrees and patterns of fonvard and backscatter. A clearly defined anti-solar point was found for plowed field, various agricultural crops and vegetated desert surfaces, while snow, the Alkali Flats, and Bonneville Salt Flats showed a broad pattern of backscatter. As a consequence of surfaces exhibiting well-defined antisolar points the anisotropic correction factors relating normal reflectances to 2π reflected values were less than 100 percent for solar angles greater than approximately 60°. All surfaces examined showed anisotropic correction factors increasing with decreasing solar angles. The albedo over the White Sands dune field decreased with decreasing solar angles due to large shadow patterns which are produced at low solar angles. The sand dunes values were derived from aircraft measurements. Comparisons were made between estimated emergent radiation from the top of the earth 's atmosphere accounting for anisotropy of the ground reflection pattern and estimates of atmospheric attenuation to values of reflected radiation obtained from the MSS subsystem of the ERTS program for the lava beds region and White Sands area in New Mexico. Also comparisons were shown between the estimated emergent radiation from the earth's surface for the same features and spectral bands to the values sensed in space. Under high albedo conditions as found in the White Sands area there was a decrease in emergent radiation to space while with low surface albedo, such as the lava beds region, the extra-terrestrial radiation increased from the ground values.
86

Flying Qualities Built-in-Test for Unmanned Aerial Systems

Chiu, Alton Pak-Hin 01 June 2012 (has links) (PDF)
This paper presents a flying qualities built-in-test for UAS application with the scope limited to the longitudinal axis. A doublet input waveform excites the AV and both α and q are used by EUDKF to estimate the A and B matrices which are short period approximations of the system. ζ, ω, GM, PM, observability, and controllability are calculated to determine flying qualities with the results displayed to the AVO in a color-coded, easy to interpret display. While SID algorithms have been flying in vehicles with adaptive control schemes, vehicles with other schemes (such as classical feedback) lack this built-in self assessment tool. In addition, adaptive control SID results are not analyzed and displayed but instead used internally. This work intends to extend this self-assessment option to all UASs regardless of control scheme as a “plug-and-play” add-on by building a reliable and robust tool that requires little tuning.
87

Conceptual Assessment of an Oblique Flying Wing Aircraft Including Control and Trim Characteristics

Plumley, Ryan W. 03 April 2008 (has links)
A method was developed to assist with the understanding of a unique configuration and investigate some of its stability and control attributes. Oblique wing aircraft concepts are a design option that is well understood, but has yet to be used in a production aircraft. Risk involved in choosing such a design can be averted through additional knowledge early in the concept evaluation phase. Analysis tools commonly used in early conceptual level analysis were evaluated for applicability to a non-standard aircraft design such as an oblique flying wing. Many tools used in early analyses make assumptions that are incompatible with the slewed wing configuration of the vehicle. Using a simplified set of tools, an investigation of a unique configuration was done as well as showing that the aircraft could be trimmed at given conditions. Wave drag was investigated to determine benefits for an oblique flying wing. This form of drag was reduced by the distribution of volume afforded by the slewing of the aircraft's wing. Once a reasonable concept was developed, aerodynamic conditions were investigated for static stability of the aircraft. Longitudinal and lateral trim were established simultaneously due to its asymmetric nature. / Master of Science
88

En modern porträttering av en levande myt : En tematisk analys av The New York Times från 2017 till 2023 kring UFO-fenomenet / A modern portrayal of a living myth : A thematic analysis of The New York Times from 2017 to 2023 about the UFO-phenomenon

Aldén, Anton, Bruhn, Magnus January 2024 (has links)
Over the last years the UFO-phenomenon has created considerable attraction in US-media. The reasons are twofold: 1) Since the fall of 2017 there has been an increased official acknowledgement of the phenomena 2) Several spectacular revelations have been publicized, both triggering a lager media coverage. But why is this topic so salient in the US? How are media and UFO-coverage interrelated?  Our thesis investigates the coverage of the phenomena in one of the largest US media outlets, The New York Times. Focusing on the period 15 December 2017 – 1 August 2023, when the acknowledgement of Pentagons secret UFO-program also known as Advanced Aerospace Threat Identification Program (AATIP) happened. Then on 26 July 2023, a whistleblower by the name of David Grusch testified in front of congress with allegations of a government conspiracy – including the possession of Alien vehicles and non-human biologics. Therefore, we have selected 51 articles and carried out a thematic analysis. We have not studied other US news outlets because The New York Times brought some serious legitimacy to the UFO-phenomena with their 2017 article about the Pentagons secret UFO-program and got financial resources to dig deep – a sensationalism you might not find elsewhere.  In the results, we were able to present two themes that emerged during the process. These were rivalry between two nations and public disclosures and reactions from the public. The rivalry between the two nations resulted in three subcategories: the near space area, spy balloons, and technological threat perception. In the theme of public reactions, we used six subcategories. These included scientific skepticism, UFO observations and reports, the desired understanding of the public, government confirmation of the secret UFO program AATIP, increased transparency and scientific discussion, and also whistleblower testimonies. This made us to answer our research questions, which were as follows: How has The New York Times' reporting on the UFO phenomenon been shaped from December 15, 2017, to August 1, 2023? Are there patterns and variations in how The New York Times has treated UFO-related articles during the aforementioned time period?
89

Cooperative Navigation in Space in-proximity of Small Bodies

Kottayam Viswanathan, Vignesh January 2021 (has links)
Autonomous proximity operations are the future of Deep space robotic exploration for searchof life, mining for resources and to establish outposts. Part of that future depends on howwell the spacecraft is capable to navigate around the complex environment of the smallcelestial body. The shift from huge monolithic spacecraft to a lightweight distributed Spacesystems has opened up a new opportunity for early characterization and global mappingmissions around these bodies. This project aims to contribute to help solve a part of thedream, wherein multiple spacecrafts operate cooperatively in proximity of small celestialbodies. To that extent, a 6 DoF controlled software-in-loop simulation is performed withsimulated optical sensors and IMU on board the spacecraft for verification of the controlledcooperative operation of two spacecrafts in a Leader-Follower configuration.
90

A Critical Study of Linear and Nonlinear Satellite Formation Flying Control Methodologies From a Fuel Consumption Perspective

Ghosh, Pradipto 08 October 2007 (has links)
No description available.

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