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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.
131

Propuesta de un sistema alternativo de transporte de carga a los sistemas de transporte empleados en la región amazónica de la selva del Perú, mediante el uso de vehículos aéreos del tipo dirigible / Proposal for an alternative cargo transportation system to the transportation systems used in the amazon region of the peruvian jungle, through the use of airship-type air vehicles

Ibárcena Balbuena, Jesús Armando 08 April 2022 (has links)
Los Dirigibles forman parte del grupo de tecnologías prometedoras que buscan impulsar el desarrollo de la humanidad a gran escala. Si bien es cierto, estas aeronaves ya han surcado los cielos durante las primeras décadas del siglo XX, su desarrollo y operación fue interrumpido por uno de los más graves accidentes que han conmocionado a la humanidad. Han pasado décadas y hoy nos encontramos en una mejor posición tecnológica como para hacer que estos gigantes vuelvan a levantar vuelo de una manera segura. A pesar del desarrollo y avance científico alcanzado, aún no hemos logrado integrar a los pueblos ubicados en regiones de difícil acceso; aunque podría hacerse con los sistemas de transporte actuales, los costos serían demasiado onerosos y no muchos países tienen los recursos como para invertir en la infraestructura requerida; sumado a esto, está el deterioro del medio ambiente producto del incremento del consumo de combustibles fósiles por medio de aviones, barcos y camiones. Los dirigibles, son una buena alternativa para intentar cambiar el rumbo, su tecnología ya ha sido probada con éxito en el pasado y con los nuevos avances tecnológicos su futuro se presenta prometedor. En el Perú, existen muchas poblaciones ubicadas en regiones de difícil acceso, que no han logrado ser desarrolladas ni integradas completamente al sistema nacional; los dirigibles tienen la capacidad de poder lograr este objetivo y de brindar a estos pueblos esa oportunidad que han venido esperando por mucho tiempo. El presente trabajo evalúa, desde un punto de vista estratégico, los beneficios de poner en marcha el empleo de dirigibles en las actividades del transporte de carga en la Selva del Perú. / Airships are part of a group of promising technologies that seek to drive human development on a large scale. While it is true, these aircraft have already crossed the skies during the first decades of the 20th century, their development and operation was interrupted by one of the most serious accidents that have shocked humanity. Decades have passed and today we are in a better technological position to make these giants take flight again safely. Despite the development and scientific progress achieved, we have not yet managed to integrate the peoples located in regions of difficult access; Although it could be done with current transportation systems, the costs would be too onerous and not many countries have the resources to invest in the required infrastructure; In addition to this, there is the deterioration of the environment as a result of the increase in the consumption of fossil fuels by means of airplanes, ships and trucks. Airships are a good alternative to try to change course, their technology has already been successfully tested in the past and with new technological advances, their future looks promising. In Peru, there are many populations located in regions of difficult access, which have not managed to be fully developed or integrated into the national system; airships have the ability to achieve this goal and to provide these peoples with the opportunity they have been waiting for a long time. Through this work, the benefits of launching the use of airships in cargo transport activities in the Peruvian Jungle are evaluated from a strategic point of view. / Trabajo de investigación
132

Drones to the Rescue : A literary study of Unmanned Aerial Systems within healthcare

Ersson, Lisbet, Olsson, Emma January 2020 (has links)
This thesis addresses the subject of drone deliveries within healthcare to examine whether unmanned aerial vehicles can contribute with increased accessibility to medical supply. An overview of the advancements made in the field since its introduction in health care, is first presented in the report. Through a literary review on the subject, dimensions have been identified as significant for determining the possibly increased accessibility to medical equipment that the unmanned aerial system provides, and thus the utility of the system. This thesis further evaluates the system out of an accessibility perspective, which aims to meet theoretical criteria established by previous researchers in the accessibility field, and thereby adopt a holistic approach to the subject. It is concluded that the dimensions are dependent on characteristics of the geographical location and should be considered when discussing drones in medicine. However, knowledge and evaluations are lacking from regions that have implemented such a system, which contributes to uncertainties for how drone deliveries work in practice.
133

On the utilization of Nonlinear MPC for Unmanned Aerial Vehicle Path Planning

Lindqvist, Björn January 2021 (has links)
This compilation thesis presents an overarching framework on the utilization of nonlinear model predictive control(NMPC) for various applications in the context of Unmanned Aerial Vehicle (UAV) path planning and collision avoidance. Fast and novel optimization algorithms allow for NMPC formulations with high runtime requirement, as those posed by controlling UAVs, to also have sufficiently large prediction horizons as to in an efficient manner integrate collision avoidance in the form of set-exclusion constraints that constrain the available position-space of the robot. This allows for an elegant merging of set-point reference tracking with the collision avoidance problem, all integrated in the control layer of the UAV. The works included in this thesis presents the UAV modeling, cost functions, constraint definitions, as well as the utilized optimization framework. Additional contributions include the use case on multi-agent systems, how to classify and predict trajectories of moving (dynamic) obstacles, as well as obstacle prioritization when an aerial agent is in the precense of more obstacles, or other aerial agents, than can reasonably be defined in the NMPC formulation. For the cases of dynamic obstacles and for multi-agent distributed collision avoidance this thesis offers extensive experimental validation of the overall NMPC framework. These works push the limits of the State-of-the-Art regarding real-time real-life implementations of NMPC-based collision avoidance. The works also include a novel RRT-based exploration framework that combines path planning with exploration behavior. Here, a multi-path RRT * planner plans paths to multiple pseudo-random goals based on a sensor model and evaluates them based on the potential information gain, distance travelled, and the optimimal actuation along the paths.The actuation is solved for as as the solutions to a NMPC problem, implying that the nonlinear actuator-based and dynamically constrained UAV model is considered as part of the combined exploration plus path planning problem. To the authors best knowledge, this is the first time the optimal actuation has been considered in such a planning problem. For all of these applications, the utilized optimization framework is the Optimization Engine: a code-generation framework that generates a custom Rust-based solver from a specified model, cost function, and constraints. The Optimization Engine solves general nonlinear and nonconvex optimization problems, and in this thesis we offer extensive experimental validation of the utilized Proximal-Averaged Newton-type method for Optimal Control (PANOC) algorithm as well as both the integrated Penalty Method and Augmented Lagrangian Method for handling the nonlinear nonconvex constraints that result from collision avoidance problems.
134

Systems Engineering of a Medical Emergency Drone – AmbiFly

Wani, Bhavika January 2020 (has links)
No description available.
135

Characteristics of instream wood following alluvial river restoration : Using Uncrewed Aerial Vehicles / Egenskaper hos död ved efter en restaurering av ett alluvialt vattendrag : Användning av obemannade flygfordon

Fjällberg, Martina January 2023 (has links)
River restoration is something that is often used to help restore watercourses that were historically used for timber floating. In these restorations, instream wood (IW) plays a big role in increasing biodiversity and habitat heterogeneity in watercourses. Uncrewed Aerial Vehicles (UAVs) have proven to be useful when monitoring changes following river restoration but there is a need for less time-consuming methods to detect IW. This study’s objective was to investigate IW following a river restoration in an alluvial reach in Vargån, Northern Sweden and how well UAVs can be used to do this. Manual digitizing of IW was done in GIS from orthomosaics of three different flight occasions: pre-restoration, directly after and one year after restoration. An object- and color-based automated image thresholding was done to investigate if it could be used to automatically detect IW. The results showed that there were differences in number of IW, volume, width, and length between the different flight occasions. There was also indication that there had been movement of IW as well as changes in cluster composition, with more clusters with a higher number of wood pieces in the latest flight occasion. The automated image thresholding was able to accurately detect IW with an accuracy of 47,4 %, but it had limitations due to natural conditions. However, it showed the possibility of using automated methods to detect IW and with improvements it could become a faster and more accessible way of detecting IW in river monitoring.
136

Decentralized Decision Making and Information Sharing in a Team of Autonomous Mobile Agents

Liao, Yan January 2012 (has links)
No description available.
137

Chance-Constrained Path Planning in Unstructured Environments

Aggarwal, Rachit January 2021 (has links)
No description available.
138

Direct multispectral photogrammetry for UAV-based snow depth measurements / Direkt multispektral fotogrammetri för UAV-baserade snödjupsmätningar

Maier, Kathrin January 2019 (has links)
Due to the changing climate and inherent atypically occurring meteorological events in the Arctic regions, more accurate snow quality predictions are needed in order to support the Sámi reindeer herding communities in northern Sweden that struggle to adapt to the rapidly changing Arctic climate. Spatial snow depth distribution is a crucial parameter not only to assess snow quality but also for multiple environmental research and social land use purposes. This contrasts with the current availability of affordable and efficient snow monitoring methods to estimate such an extremely variable parameter in both space and time. In this thesis, a novel approach to determine spatial snow depth distribution in challenging alpine terrain is presented and tested during a field campaign performed in Tarfala, Sweden in April 2019. A multispectral camera capturing five spectral bands in wavelengths between 470 and 860 nanometers on board of a small Unmanned Aerial Vehicle is deployed to derive 3D snow surface models via photogrammetric image processing techniques. The main advantage over conventional photogrammetric surveys is the utilization of accurate RTK positioning technology that enables direct georeferencing of the images, and thus eliminates the need for ground control points and dangerous and time-consuming fieldwork. The continuous snow depth distribution is retrieved by differencing two digital surface models corresponding to the snow-free and snow-covered study areas. An extensive error assessment based on ground measurements is performed including an analysis of the impact of multispectral imagery. Uncertainties and non-transparencies due to a black-box environment in the photogrammetric processing are, however, present, but accounted for during the error source analysis. The results of this project demonstrate that the proposed methodology is capable of producing high-resolution 3D snow-covered surface models (< 7 cm/pixel) of alpine areas up to 8 hectares in a fast, reliable and cost-efficient way. The overall RMSE of the snow depth estimates is 7.5 cm for data acquired in ideal survey conditions. The proposed method furthermore assists in closing the scale gap between discrete point measurements and regional-scale remote sensing, and in complementing large-scale remote sensing data by providing an adequate validation source. As part of the Swedish cooperation project ’Snow4all’, the findings of this project are used to support and validate large-scale snow models for improved snow quality prediction in northern Sweden. / På grund av klimatförändringar och naturliga meteorologiska händelser i arktis behövs mer exakta snökvalitetsprognoser för att stödja samernas rensköttsamhällen i norra Sverige som har problem med att anpassa sig till det snabbt föränderliga arktiska klimatet. Rumslig snödjupsfördelning är en avgörande parameter för att inte bara bedöma snökvaliteten utan även för flera miljöforskning och sociala markanvändningsändamål. Detta står i motsats till den nuvarande tillgången till överkomliga och effektiva metoder för snöövervakning för att uppskatta sådan extremt varierande parameter i tid och rum. I detta arbete presenteras och testas en ny metod för att bestämma rumslig snödjupssdistribution i utmanande alpin terräng under en fältstudie som genomfördes i Tarfala i norra Sverige i april 2019. Via fotogrammetrisk bildbehandlingsteknik hämtades snöytemodeller i 3D med hjälp av en multispektral kamera monterad på en liten obemannad drönare. En viktig fördel, i jämförelse med konventionella fotogrammetriska undersökningar, är användningen av exakt RTK-positioneringsteknik som möjliggör direkt georeferencing och eliminerar behovet av markkontrollpunkter. Den kontinuerliga snödjupfördelningen hämtas genom att ytmodellerna delas upp i snöfria respektive snötäckta undersökningsområden. En omfattande felsökning som baseras på markmätningar utförs, inklusive en analys av effekten av multispektrala bilder. Resultaten från denna studie visar att den famtagna metoden kan producera högupplösta snötäckta höjdmodeller i 3D (< 7 cm/pixel) av alpina områden på upp till 8 hektar på ett snabbt, pålitligt och kostnadseffektivt sätt. Den övergripande RMSE för det beräknade snödjupet är 7,5 cm för data som förvärvats under idealiska undersökningsförhållanden. Som ett led i det svenska projektet “Snow4all” används resultaten från projektet för att förbättra och validera storskaliga snömodeller för att bättre förutse snökvaliteten i norra Sverige.
139

Managing Validation in a Safety Critical System Regarding Automation of Air Traffic Control

De Freitas Martinez, Andres, Mohamed, Nurdin January 2018 (has links)
The aviation industry is under increasing pressure to reduce cost and manage the increased number of passengers. One area under pressure is the Air Traffic Control. The Air Traffic Control will in a foreseeable future manage the introduction of drones also known as Unmanned Aerial Vehicles by integrating them into civil airspace with manned aircraft. Drones are lacking consensus from authorities with regards to standards due to their rapid expansion. Given their size, shape and speed, they can also pose threats to manned aircrafts and there is a need to address them in an Air Traffic Management system interoperating with manned aircrafts. The purpose in this study is to identify what considerations to make when automating complex system elements with respect to safety. Safety involves all the different stakeholders in the air transportation system, which is a Safety critical System. Furthermore, the aim is also to identify areas in which European Operational Concept Validation Methodology (E-OCVM) can be complemented with. Standard E-OCVM is missing specific assessment criteria with regards to safety and how it can interact with other standards. The approach is thereby to use various standards with focus on Systems Engineering to complement E-OCVM since it is lacking with regards to how it is used to validate Air Traffic Control systems. To capture the complexity of automating elements of an industry involving many stakeholders, a qualitative analysis was conducted in this project, using a System Engineering approach with four standards A-SLP, A-RLP, A-DAS and A-SAS. A-SLP and A-RLP are two general standards while A-DAS and A-SAS are focusing on the contexts of aircrafts and software development. Empirical data was gathered by semi-structured interviews of seven experts within the relevant areas in the field. From the review of the four standards, it was found that they can for instance complement E-OCVM in how software errors can lead to a failure condition among other ways. The main identified considerations faced with an integration of drones into civil airspace, is to manage the human interaction with the introduced Air Traffic Management systems. More specifically, the human element must be involved from the training phase in the development of systems in a Safety Critical System to minimize risk. Furthermore, redundancies that are built into the system has to, not only be able to put the system into a safe state, but also be carefully analyzed in how they interact with other systems to avoid misjudgement for the Air Traffic Controllers. Lastly, to obtain specific details on how interoperability could occur using standards, the standards used in this study refer to usage of other documents and standards. Standards specifically tailored for the operational context of drones would facilitate further testing and implementation of their integration into civil airspace. Given that different standards were used to complement the EOCVM standard, a set of unified standards are required that are proportional with the type of drones, the type of operations and in the environment that they are operating in. This will be needed to fulfill the European vision of safe integration of drones and needs thereby to be carried out in a global manner, thus also share experience with other actors to advance the new technology adaptation.
140

A Path Planning Approach for Context Aware Autonomous UAVs used for Surveying Areas in Developing Regions / En Navigeringsstrategi för Autonoma Drönare för Utforskning av Utvecklingsregioner

Kringberg, Fredrika January 2018 (has links)
Developing regions are often characterized by large areas that are poorly reachable or explored. The mapping and census of roaming populations in these areas are often difficult and sporadic. A recent spark in the development of small aerial vehicles has made them the perfect tool to efficiently and accurately monitor these areas. This paper presents an approach to aid area surveying through the use of Unmanned Aerial Vehicles. The two main components of this approach are an efficient on-device deep learning object identification component to capture and infer images with acceptable performance (latency andaccuracy), and a dynamic path planning approach, informed by the object identification component. In particular, this thesis illustrates the development of the path planning component, which exploits potential field methods to dynamically adapt the path based on inputs from the vision system. It also describes the integration work that was performed to implement the approach on a prototype platform, with the aim to achieve autonomous flight with onboard computation. The path planning component was developed with the purpose of gaining information about the populations detected by the object identification component, while considering the limited resources of energy and computational power onboard a UAV. The developed algorithm was compared to navigation using a predefined path, where the UAV does not react to the environment. Results from the comparison show that the algorithm provide more information about the objects of interest, with a very small change in flight time. The integration of the object identification and the path planning components on the prototype platform was evaluated in terms of end-to-end latency, power consumption and resource utilization. Results show that the proposed approach is feasible for area surveying in developing regions. Parts of this work has been published in the workshop of DroNet, collocated with MobiSys, with the title Surveying Areas in Developing Regions Through Context Aware Drone Mobility. Thework was carried out in collaboration with Alessandro Montanari, Alice Valentini, Cecilia Mascoloand Amanda Prorok. / Utvecklingsländer är ofta karaktäriserade av vidsträcka områden som är svåråtkomliga och outforskade. Kartläggning och folkräkning av populationen i dessa områden är svåra uppgifter som sker sporadiskt. Nya framsteg i utvecklingen av små, luftburna fordon har gjort dem till perfekta verktyg för att effektivt och noggrant bevaka dessa områden. Den här rapporten presenterar en strategi för att underlätta utforskning av dessa områden med hjälp av drönare. De två huvudkomponenterna i denna strategi är en effektiv maskininlärningskomponent för objektidentifiering med acceptabel prestanda i avseende av latens och noggrannhet, samt en dynamisk navigeringskomponent som informeras av objektidentifieringskomponenten. I synnerhet illustrerar denna avhandling utvecklingen av navigeringskomponenten, som utnyttjar potentialfält för att dynamiskt anpassa vägen baserat på information från objektidentifieringssystemet. Dessutom beskrivs det integrationsarbete som utförts för att implementera strategin på en prototypplattform, med målet att uppnå autonom flygning med all beräkning utförd ombord. Navigeringskomponenten utvecklades i syfte att maximera informationen om de populationer som upptäckts av objektidentifieringskomponenten, med hänsyn till de begränsade resurserna av energi och beräkningskraft ombord på en drönare. Den utvecklade algoritmen jämfördes med navigering med en fördefinierad väg, där drönaren inte reagerar på omgivningen. Resultat från jämförelsen visar att algoritmen ger mer information om objekten av intresse, med en mycket liten förändring i flygtiden. Integreringen av objektidentifieringskomponenten och navigeringskomponenten på prototypplattformen utvärderades med avseende på latens, strömförbrukning och resursutnyttjande. Resultaten visar att den föreslagna strategin är genomförbar för kartläggning och utforskning av utvecklingsregioner. Delar av detta arbete har publicerats i DroNets workshop, samlokaliserad med MobiSys, med titeln Surveying Areas in Developing Regions Through Context Aware Drone Mobility. Arbetet utfördes i samarbete med Alessandro Montanari, Alice Valentini, Cecilia Mascolo och Amanda Prorok.

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