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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.
461

UAV hyperspectral images corrected of illumination differences considering microtopography in correction models /

Thomaz, Mariana Bardella. January 2020 (has links)
Orientador: Nilton Nobuhiro Imai / Resumo: O uso do UAV no sensoriamento remoto é uma área crescente de conhecimento e pressionou o desenvolvimento de câmeras multi e hiperespectrais leves, que poderiam ser usadas embarcadas em UAV. Como as informações espectrais dependem das condições de iluminação da cena, as imagens adquiridas por UAV exigem pesquisa para avaliar o processamento de imagens para melhor adaptar os conceitos já estabelecidos às imagens orbitais. Portanto, a correção radiométrica é de fundamental importância para a extração de dados de imagens com alta confiança, uma vez que se sabe que o fator de refletância é uma função da estrutura geométrica, ângulo solar e propriedades ópticas. Nesse sentido, foram desenvolvidas metodologias para corrigir imagens das diferenças de iluminação, utilizando as Funções de Distribuição de Refletância Bidirecional e os Modelos de Correção Topográfica, também conhecidos como correção de iluminação. Este trabalho utiliza a câmera hiperespectral Rikola a bordo de um UAV em latitudes tropicais. Ele avalia como a anisotropia pode influenciar a variabilidade na reflectância dos alvos e como os modelos de correção topográfica podem ser aplicados, usando a micro topografia, para atenuar esses efeitos. Três testes foram realizados para estudar i) as geometrias de visada da câmera hiperespectral Rikola e a disponibilidade de dados fora do Nadir, ii) a variação do fator de anisotropia entre os alvos nas geometrias de visada e iii) modelos de correção de microtopografia para corrigi... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Use of UAV in remote sensing is a growing area of knowledge and pressed the development of lightweight multi and hyperspectral cameras, which could be used on board of UAV. Since the spectral information depends on the lighting condition of the scene, UAV acquired images demands research to assess image processing to better adapt the concepts already stablished to orbital images. Therefore, the radiometric correction is of main importance for data extraction from imagery with high confidence, once it is known that the reflectance factor is a function of geometric structure, solar angle and optical properties. In this regard, methodologies were developed to correct images from illumination differences, using the Bidirectional Reflectance Distribution Functions and the Topographic Correction Models, also known as illumination correction. This Work uses Rikola hyperspectral camera onboard of a UAV in tropical latitudes. It assesses how the anisotropy can influence variability in reflectance of targets, and how topographic correction models can be applied, using micro topography, to attenuate these effects. Three tests were done to study i) the view geometries of Rikola Hyperspectral camera and the no-Nadir data availability, ii) the variation of Anisotropy Factor between targets in the many view geometries and iii) Microtopography correction models to correct illumination differences using a highly detailed DSM (10 cm and 3 cm) to assess the micro relief. We applied the correcti... (Complete abstract click electronic access below) / Mestre
462

Návrh rozložení přibližovacích linek na základě fotogrammetrie v Thajsku

Petrovičová, Lucia January 2019 (has links)
Suitable skidding trail layout is important in sustainable forestry system, thus can minimise the damages to trees and economical losses. In a cooperation between Mendel University in Brno and Kasetsart University in Bangkok a potential use of photogrammetry based skidding trail layout was evaluated. Certain plots of teak plantation in Thong Pha Phum were captured with and further processed in Agisoft Metashape software. On obtained orthophoto single trees were distinguished and understory trees for thinning from below were identified on Weighted Voronoi diagram base. On Kernel Density Estimation base a tree density estimation raster output were created. Considering irregular teak spacing a subjective approach for skidding trail layout design was applied, with emphasis to shorten skidding distances and reducing the possible damages to remaining trees and soils.
463

En kvalitativ fallstudie om implementeringen av UAV 03 Örnen i Försvarsmakten på regementet K3

Larsson, Johan January 2020 (has links)
Försvarsmaktens perspektivstudie anser det tvunget med en utveckling av obemannade flygsystem för att möta framtidens stridsmiljö. Detta medför en implementering av ett nytt obemannat flygsystem i Försvarsmakten, historien visar dock på utmaningar vid liknande implementeringar, därför är en sådan tidigare implementering relevant att studera.    Syftet med denna fallstudie gällande implementeringen av UAV 03 Örnen på regementet K3, är att bidra med ett bredare synsätt kring forskningen om organisationskultur och implementering. Utifrån studiens syfte genomförs en fallstudie där empiri inhämtas genom kvalitativa intervjuer. Inhämtad empiri analyseras utifrån implementerings- såväl som organisationskulturteori. Studiens resultat visar att implementeringen av UAV 03 på K3 kan förstås tillsammans med jägarstridens grunder om ett flexibelt uppträdande i smågrupper samt den elitism som speglar K3. Studien påvisar att intresset att åka på utlandsmission hos individen är större än att jobba med systemet UAV 03, vilket visar sig vid personalförsörjning.
464

Využití dat dálkového průzkumu Země pro sledování dlouhodobé dynamiky vegetace na krajinném měřítku / Use of remote sensing data for monitoring of long-term vegetation dynamics on the landscape scale

Brůna, Josef January 2018 (has links)
This thesis deals with the use of remote sensing data for studying and monitoring vegetation changes. Thanks to archival materials, we can now make extensive studies at the landscape and global level without the need for large-scale old field data. From the Middle Ages, we can rely on different types of maps, for vegetation studies, these are mainly forestry maps. Since the 1930's, aerial photographs have been available in Europe, and satellite imagery was available since the 1970's. Availability and quality of satellite imagery had increased rapidly during my study. The most recent data source are unmanned aerial systems and methods of processing their data, which allow inexpensive detailed mapping of large areas. The presented publications do not only solve ecological research questions, but also contribute to solving current environmental problems in the Czech Republic, from nature conservation in National Parks and protected areas to monitoring of plant invasions. I have used archival forest maps for the reconstruction and analysis of large disturbances (windthrow and subsequent gradations of bark beetle) in forests of Šumava and the Bavarian Forest in 1868-1870. Species composition, as well as environmental factors derived from digital elevation model, were analyzed. The same topic was also...
465

Time Synchronization of TDOA Sensors Using a Local Reference Signal

Hult, Alfred January 2020 (has links)
Synchronization of distributed time difference of arrival (TDOA) sensor networks can be performed using reference signals from GPS satellites. This method provides high accuracy, but is vulnerable to jamming, and is not reliable enough to be used in military applications. A solution that does not depend on any signals transmitted from external actors is preferred. One way to achieve this is to use reference signals transmitted from a UAV. A UAV is suitable since only local synchronization for a geographically restricted area is necessary. The local synchronization is achieved by estimating the time-delay between the transmission and reception of a reference signal. The estimated time-delay can be used to detect drifts in the clocks of the TDOA sensors. This thesis analyzes com- mon reference signals, to evaluate which provide high accuracy for time-delay estimation, and what properties of the signals influence the estimation accuracy the most. The simulations show that the time-delay estimation performance can reach the same accuracy as synchronization against GPS for different types of signals. An increased bandwidth is more important than an increased signal length or signal-to-noise ratio to improve the estimation accuracy.
466

Robots and Moral Agency

Johansson, Linda January 2011 (has links)
Machine ethics is a field of applied ethics that has grown rapidly in the last decade. Increasingly advanced autonomous robots have expanded the focus of machine ethics from issues regarding the ethical development and use of technology by humans to a focus on ethical dimensions of the machines themselves. This thesis contains two essays, both about robots in some sense, representing these different perspectives of machine ethics. The first essay, “Is it Morally Right to use UAVs in War?” concerns an example of robots today, namely the unmanned aerial vehicles (UAVs) used in war, and the ethics surrounding the use of such robots. In this essay it is argued that UAVs might affect how the laws of war (LOW) are interpreted, and that there might be need for additional rules surrounding the use of UAVs. This represents the more traditional approach of machine ethics, focusing on the decisions of humans regarding the use of such robots. The second essay, “The Functional Morality of Robots”, concerns the robots of the future – the potential moral agency of robots. The suggestion in this essay is that robots should be considered moral agents if they can pass a moral version of the Turing Test. This represents the new focus of machine ethics: machine morality, or more precisely, machine agency. / <p>QC 20110414</p>
467

The Condor UAV System : A Concept Study

Ramirez Alvarez, Dennis André January 2016 (has links)
In this degree project in aerospace engineering, a preliminary design of a UAV (Unmanned Aerial Vehicle) was performed. The UAV was intended to be used as a complement to the Swedish maritime administration’s helicopters, which cannot operate under limited visibility conditions. Its main mission would consist of surveillance. The UAV was therefore designed for some series criteria that were based on the customers’ requirements. The primary literature that was used was John D. Andersons Aircraft performance and design. Otherwise, historical statistical data from other aircraft was used and numerous assumptions were made. The result was a relatively small UAV named The Condor, weighing 25.6 kg with a wingspan of 2.5 m and operational in an altitude of 3500 m with a cruise speed of 81 knots. The UAV’s range is 70 nautical miles and is also able to operate in up to six hours. It should be able to manage a 300 m long runway. The chosen wing profile was the NACA 1412 with a maximal thickness and camber of 12 % and 1 % of the chord length, respectively. As for the stabilizer, the symmetric wing profile NACA 0012 was chosen. A so called constraint analysis was performed in order to determine the engine choice and thewing loading. The chosen engine was a 3.1 horsepower piston engine provided by Ricardo. The dimensions of the fuselage were designed only to fit the payload and no detailed analysis was done. It became 2.3 m long and with a maximal diameter of 0.3 m. / I det här kandidatexamensarbetet i flygteknik gjordes en preliminär design av en drönare. Drönaren skulle användas som komplettering till sjöfartsverkets helikoptrar, som inte kan användas vid mycket begränsad sikt. Dess huvudsakliga uppdrag skulle bestå av övervakning. Drönarens utformades därför efter en rad kriterier som baserades på uppdragsgivarens krav. Den huvudsakliga litteraturen som användes var John D. Andersons Aircraft performanceand design. I övrigt användes historisk statistisk data från andra flygplan och ett flertal antaganden gjordes. Resultatet blev en relativt liten drönare som döptes till The Condor och fick en vikt på 25.6 kg, med ett vingspann på 2.5 m och som opererar på 3500 m flyghöjd med en marschfart på 81 knop. Drönarens räckvidd är 70 nautiska mil och den kan därutöver operera i upp till sex timmar. Den bör klara av en landningsbana på 300 m. Som vingprofil valdes NACA 1412 med en maximal tjocklek och camber på 12 % respektive 1 % av kordalängden. För stabilisatorn valdes den symmetriska profilen NACA 0012. En så kallad ”constraint analysis” genomfördes för fastställande av motorval och vingbelastning. Motorn som valdes blev en 3.1 hästkrafters pistongmotor från Ricardo. Flygplanskroppens dimensioner utformades endast för att få plats med nyttolasten och ingen noggrannare analys genomfördes. Den blev 2.3 m lång med en maximal diameter på0.3 m.
468

Vulnerability Analysis of Infrastructure Systems

Lane, Sean Theodore 07 July 2020 (has links)
Complex cyber-physical systems have become fundamental to modern society by effectively providing critical services and improving efficiency in various domains. Unfortunately, as systems become more connected and more complex, they also can become more vulnerable and less robust. As a result, various failure modes become more common and easily triggered from both unanticipated and malicious perturbations. Research has been conducted in the area of vulnerability analysis for cyber-physical systems, to assist in locating these possible vulnerabilities before they can fail. I present two case studies on different forms of critical infrastructure systems to identify vulnerabilities and understand how external perturbations can affect them, namely UAV drone swarms and municipal water infrastructure.
469

Observatörer ett verktyg mot drönare?

Roth, Dennis January 2022 (has links)
Att försvara sig mot drönare är idag en del av alla militära funktioner, där militärmakter måste anpassa sig tillden snabba tekniska utvecklingen. Drönare används inte längre endast för militära syften, utan kan användasav civila, rebeller eller icke statsaktörer. Idag är drönare relativt billiga, lätta att få tag på och produceras i enhög takt. Tekniken för detektion av drönare som finns i idag är inte helt tillförlitlig där exempel påsvårigheter är att det finns att urskilja drönaren från andra objekt och ger olika resultat beroende på olikaväderförhållanden. Syftet med arbetet var att beskriva hur Försvarsmakten kan använda observatörer fördetektering av små drönare när tekniska hjälpmedel inte finns tillgängliga, och därtill vilka tekniska alternativsom finns på marknaden idag för detektering av små drönare. Arbetet syftar även till att undersöka på vilkaavstånd förbanden kan förväntas upptäcka drönare genom att använda observatörer utan extra tekniskutrustning.I arbetet genomförs ett experiment i syfte att bekräfta tidigare studier om på vilka avstånd en observatör kanupptäcka en drönare, både visuellt och med hörseln. I studien framkom att 50 procent av testdeltagarnadefinitivt kunde upptäcka drönaren på cirka 360m. I arbetet genomfördes en tematisk analys mot militär nyttamellan olika tekniska system för detektion av drönare. Utifrån analysen framkom slutsatserna att enobservatör inte har möjlighet att upptäcka en drönare innan den hinner samla in underrättelser utan att varautplacerad långt från skyddsobjektet. Den mest lämpliga metoden om man ska använda en observatör ärdärför att använda en kombination tillsammans med något annat tekniskt system.
470

Field Validation of an Advanced Autonomous Method of Exterior Dam Inspection Using Unmanned Aerial Vehicles

Barrett, Benjamin Joseph 01 July 2018 (has links)
The maintenance of infrastructure is critical to the well-being of society. This work focuses on a novel method for inspecting the exterior of dams using unmanned aerial vehicles (UAVs) in an automated fashion. The UAVs are equipped with optical sensors capturing still images. The resulting images are used to generate three-dimensional (3D) models using Structure from Motion (SfM) computer software. The SfM models are then used to inspect the exterior of the dam. As typical dam inspections entail completing a checklist of inspection items with varied degrees of precision (e.g. a concrete spillway may be finely inspected for cracking or joint deterioration while the general stability and water-tightness of a large embankment may be observed from a distance), a targeted inspection is also needed for the UAV method. In conjunction with the work presented in this thesis, a novel algorithm was developed which uses camera view planning across multiple proximity levels to generate a set of camera poses (positions and orientations) which can be collected in an autonomous UAV flight that facilitates generation of SfM models having tiered model quality for targeted inspection of infrastructure features. In this thesis, this novel algorithm and accompanying mobile application (referred to together as the novel advanced autonomous method) were field validated at Tibble Fork Dam, UT. The advanced autonomous method was compared to two other common image acquisition methods—basic autonomous and manual piloted—based on the SfM models produced from the collected image sets. The advanced autonomous method was found to produce models having tiered quality needed for efficient targeted inspection (25% and 50% higher resolution in medium and high priority target areas). The advanced autonomous method was found to produce models having on average 38% higher precise point accuracy (1.3cm) and 53% tighter surface reproducibility (for repeat inspections) (1.9cm) than basic autonomous and manual piloted image acquisition methods. The advanced autonomous method required on average 167% longer flight time and 38% fewer images than the other two methods, resulting in increased field time but decreased processing load. Additionally, viability of the advanced autonomous method for practical dam inspection was assessed through a case study inspection of Tibble Fork Dam using the collected SfM model and corresponding still images. The SfM model and corresponding images were found fully adequate for performing 94% of the inspection tasks and partially adequate for the remaining tasks. In consideration of this and other practical implementation factors such as time and safety, the method appears highly viable as an alternate to or supplement with traditional on-foot visual exterior inspection of dams such as Tibble Fork Dam. Suggestions for future work include adjustments to the optimization framework to improve field efficiency, development of a framework for cooperative inspection using UAV swarms, and development of a more automated workflow that would allow fully-remote dam inspections.

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