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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.
101

Modeling and Detecting Orbit Observation Errors Using Statistical Methods

Christopher Y Jang (8918840) 15 June 2020 (has links)
In the globally collaborative effort of maintaining an accurate space catalog, it is of utmost importance for ground tracking stations to provide observations which can be used to update and improve the catalog. However, each tracking station is responsible for viewing thousands of objects in a limited window of time. Limitations in sensor capabilities, human error, and other circumstances inevitably result in erroneous, or unusable, data, but when receiving information from a tracking station, it may be difficult for the end-user to determine a data set's usability. Variables in equipment, environment, and processing create uncertainties when computing the positions and orbits of the satellites. Firstly, this research provides a reference frame for what degrees of errors or biases in equipment translate to different levels of orbital errors after a least squares orbit determination. Secondly, using just an incoming data set's angle error distribution compared to the newly determined orbit, statistical distribution testing is used to determine the validity and usability of the newly received data set. In the context of orbit position uncertainty, users are then able to communicate and relay the uncertainties in the data they share while assessing incoming data for potential sources of error.
102

Orbital Perturbations for Space Situational Awareness

Smriti Nandan Paul (9178595) 29 July 2020 (has links)
<pre>Because of the increasing population of space objects, there is an increasing necessity to monitor and predict the status of the near-Earth space environment, especially of critical regions like geosynchronous Earth orbit (GEO) and low Earth orbit (LEO) regions, for a sustainable future. Space Situational Awareness (SSA), however, is a challenging task because of the requirement for dynamically insightful fast orbit propagation models, presence of dynamical uncertainties, and limitations in sensor resources. Since initial parameters are often not known exactly and since many SSA applications require long-term orbit propagation, long-term effects of the initial uncertainties on orbital evolution are examined in this work. To get a long-term perspective in a fast and efficient manner, this work uses analytical propagation techniques. Existing analytical theories for orbital perturbations are investigated, and modifications are made to them to improve accuracy. While conservative perturbation forces are often studied, of particular interest here is the orbital perturbation due to non-conservative forces. Using the previous findings and the developments in this thesis, two SSA applications are investigated in this work. In the first SSA application, a sensor tasking algorithm is designed for the detection of new classes of GEO space objects. In the second application, the categorization of near-GEO objects is carried out by combining knowledge of orbit dynamics with machine learning techniques.</pre>
103

Visual Substitutes for Audio Cues - Providing situational awareness for players with auditory disabilities

Haddad, David, Strand, Casper January 2019 (has links)
Spel har förvandlats till en mainstream underhållningskälla och har utvecklats tillsammans med teknologin. Till en nivå som nyttjar en spelares alla sinnen för att fördjupa de i ett spel. Uppmärksamheten kring tillgänglighet inom spel har dock försvagats.Detta examensarbete undersöker de tillgängliga lösningarna som syftar till att hjälpa döva eller hörselskadade, främst när det gäller situationsmedvetenhet genom att ersätta ljud med en visuell representation. De i skrivande stund tillgängliga lösningarna jämförs sedan med resultaten i relaterad forskning och en undersökning som genomfördes för detta arbete. Målsättningen var att hitta vad som fungerade som en visuell representation av ljud, med undersökningssvaren som ger insikt i döva och hörselskadade individers perspektiv på lösningarna.Dessa resultat kan fungera som en referenspunkt för utvecklare som vill implementera en visuell representation av ljud eller liknande funktion i deras spel. / Video Games have turned into a mainstream source of entertainment and have evolved alongside technological improvements. To the point of being able to bring the player immersive gaming experiences that rely heavily on their senses. However, the attention to the accessibility aspects of video games has been lagging behind.This thesis explores the available solutions that aim to help Deaf or Hard of Hearing (DHH) players, primarily in terms of situational awareness by substituting audio with a visual representation. The currently available solutions are then compared with the findings in related research and a survey that was conducted for this paper. The objective was to find what worked as a visual representation of audio, with the survey responses providing insight into DHH players perspective.These findings can serve as a reference point for developers who want to implement a visual substitute for audio or a similar feature intheir game.
104

Situational Awareness Monitoring for Humans-In-The-Loop of Telepresence Robotic Systems

Kanyok, Nathan J. 21 November 2019 (has links)
No description available.
105

The future of Remote Operations for Autonomous Vehicles : Exploring Human-Automation Teamwork and Situational Awareness for SAE Level 4 trucks

Klingberg, Linnea January 2023 (has links)
The level of autonomation and the number situations which an autonomous vehicle can handle continuously increases. However, even fully autonomous vehicles will need human support, especially when system failures occur. Remote operations enables vehicles to operate autonomously when possible and keeps the human in the loop to assist when needed by allocating them to a remote operating center (ROC). It is a new field within autonomous trucks and little research has thus been conducted on the topic. By taking an approach from the fields of aviation and maritime, where remote operations has been researched for longer, the study aims to transfer knowledge to road freight and to enable remote operations at a management mode. The focus of the study is thus to investigate which information is important for the remote operator (RO) when manual procedures are automated, and to define recommendations for how a ROC could be designed from a human-automation teamwork and situational awareness perspective. The results of the conducted interviews find that the RO first and foremost needs information regarding failures of the automation, including how the failures could be solved. However, it also confirms previous research emphasizing interactive interfaces to avoid passive monitoring, as that is likely to cause an out-of-the-loop problem. Furthermore, recommendations which could be defined regarding the design of a ROC include incorporating both verbal and digital communicational abilities, and the possibility to collaborate, both internally and externally. Lastly, the results show an importance to differentiate between different modes of remote operations in the ROC to remain clear of the responsible actor and avoiding automation surprise.
106

Towards Efficient Incident Detection in Real-time Traffic Management

Torrent-Fontbona, Ferran, Dominguez, Monica, Fernandez, Javier, Casas, Jordi 23 June 2023 (has links)
Incident detection is a key component in real-time traffic management systems that allows efficient response plan generation and decision making by means of risk alerts at critical affected sections in the network. State-of-the-art incident detection techniques traditionally require: i) good quality data from closely located sensor pairs, ii) a minimum of two reliable measurements from the flow- occupancy-speed triad, and iii) supervised adjustment of thresholds that will trigger anomalous traffic states. Despite such requirements may be reasonably achieved in simulated scenarios, real-time downstream applications rarely work under such ideal conditions and must deal with low reliability data, missing measurements, and scarcity of curated incident labelled datasets, among other challenges. This paper proposes an unsupervised technique based on univariate timeseries anomaly detection for computationally efficient incident detection in real-world scenarios. Such technique is proved to successfully work when only flow measurements are available, and to dynamically adjust thresholds that adapt to changes in the supply. Moreover, results show good performance with low-reliability and missing data.
107

Initial Orbit Determination of Resident Space Objects From A Passive Optical Imaging System: : Application to Space Situational Awareness

McKenna, Jessica January 2023 (has links)
The probability of satellite collisions and disintegrations cluttering the near-Earth orbital environmentis ever-growing. This is especially true for the congested Low Earth Orbit (LEO) regime; once a critical density of objects is reached, a collisional cascading is projected to generate runaway growth of theorbital population. Comprehensive tracking of Resident Space Objects (RSO) is a requisite precursor to conjunction forecasting and avoidance; a strategy for active debris mitigation. Conducted at Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) Andøya Space, this work presents a means through which a passive optical observation station can be established using only an off-the shelf Canon EOS-1300 camera for uncued detection. A custom processing pipelinewas developed to perform data reduction on the retrieved images and initialisation of the object orbit was accomplished via implementations of the classic Initial Orbit Determination (IOD) algorithms of Laplace and Gauss. RSO identification was performed by reconstruction of the overpass and comparison against objects in a Two Line Elements (TLE) database. The complete script initiates the tracking process, and requires no inputs other than the image, and the geodetic coordinates of the ground station. The processing pipeline was demonstrated to perform robustly on the collected images and the algorithms were tested for different orbital regimes using precision angular data extracted from literature, with the retrieved results corresponding closely to the available reference values for all orbital regimes. Their performance as predictors of satellite position was compared for a variety of test cases, withthe Gauss algorithm producing more consistent results. However, orbits could not be initialised from the images, due to insufficient angular and timing precision. Various adaptations and extensions are suggested in order to achieve the requisite accuracy in the optical data and improve the data collection.
108

Menschliches Fehlverhalten bei der Steuerung des Eisenbahnbetriebs

Dorman, Peter 07 August 2023 (has links)
Zur Beurteilung der Rolle von menschlichen Faktoren bei Eisenbahnunfällen wurden 41 Untersuchungsberichte der Bundesstelle für Eisenbahnunfalluntersuchung einer strukturierten Inhaltsanalyse unterzogen und die Handlungen von Fahrdienstleitern (Fdl) und Triebfahrzeugführern (Tf) in Kategorien zu Fehlerklassifikationen nach Reason und Ebenen des Situationsbewusstseins nach Endsley eingeteilt. Darauf aufbauend wurden Hypothesen abgeleitet, welche in einem Online-Fragebogen untersucht wurden. Es wurde dabei mit Einstichproben t-Tests gegen durch Expertenwissen definierte Cutoff-Werte festgestellt, dass das Sicherheitsklima unter Fdl und Tf niedrig ist, dass Fdl Fahrstraßen zu früh auflösen, dass Fdl Hilfssperren bewusst nicht immer anbringen, dass Fdl Fahrwegprüfungen durch Hinsehen nicht mit angemessener Sorgfalt durchführen, dass Tf sich nach Zwangsbremsungen nicht an die Vorgaben halten, dass Tf nicht alle für sie geltenden Signale wahrnehmen und dass Tf bewusst schneller als erlaubt fahren. Mit einem Zweistichproben-t-Test wurde getestet, ob die meisten Fehler von Fdl und Tf auf der Ebene der Wahrnehmung nach Endsley im Vergleich zu den Ebenen des Verständnisses und der Projektion passieren, lieferte aber kein signifikantes Ergebnis. Es konnte herausgearbeitet werden, dass in Deutschland im Bereich der Unfallanalyse Verbesserungspotenziale bestehen und sich dabei an anderen Hochrisikobranchen orientiert werden kann.:1 Motivation ........................................................................................................... 9 2 Theorie: Fehler und Sicherheit im System Bahn .......................................... 10 2.1 Fehlerdefinition nach Reason................................................................ 10 2.2 Situationsbewusstsein nach Endsley.................................................... 12 2.3 Theorie der wissenschaftlichen Fragebogenerstellung und Statistischen Analyse.............................................................................. 13 2.4 Sicherheitskultur und Sicherheitsklima............................................... 15 2.5 Sicherheit im System Bahn .................................................................... 16 2.6 Bedeutung des Menschen im System Bahn ......................................... 17 2.7 Abstraktionen von Sicherheit und Fehlern im System Bahn............. 19 2.8 Selbstschutz vor Fehlern ........................................................................ 21 2.9 Ziel der Untersuchungsberichte der Bundesstelle für Eisenbahnunfalluntersuchung (BEU).................................................... 22 3 Methodik dieser Arbeit.................................................................................... 24 3.1 Vorgehen .................................................................................................. 24 3.2 Ergebnisse der Analyse ........................................................................... 27 3.2.1 Auswertung nach Reason ................................................................ 28 3.2.2 Auswertung Situationsbewusstsein ................................................ 31 3.2.3 Mangelhafte Fahrwegprüfung ......................................................... 32 3.2.4 Unzeitiges Umstellen von Weichen................................................. 33 3.2.5 Hilfssperren....................................................................................... 34 3.2.6 Kommunikation, Funkdisziplin, Team-SA und Notrufe ................. 35 3.2.7 Frühzeitiges Auflösen von Fahrstraßen .......................................... 38 3.2.8 Geschwindigkeitsüberschreitungen................................................ 38 3.2.9 Verhalten von Tf nach Zwangsbremsungen................................... 39 3.2.10 Wahrnehmung von und Vorbeifahrt an Halt zeigenden Signalen 40 3.2.11 Auswertung der Zwischenberichte.................................................. 40 3.2.12 Einsatzdauer auf dem Stellwerk als Kriterium für die Wahrscheinlichkeit einer unsicheren Handlung ............................ 41 3.2.13 Sicherheitsklima................................................................................ 41 4 Fragebogenerstellung ...................................................................................... 42 4.1 Hypothesenbildung................................................................................. 42 4.2 Frageformen und Antwortmöglichkeiten ............................................ 42 4.3 Ablauf der Befragung.............................................................................. 43 4.4 Anzahl der Items pro Hypothese........................................................... 44 4.5 Rekrutierung............................................................................................ 44 4.6 Beschreibung der Stichprobe................................................................. 46 4.7 Gütekriterien des Fragebogens ............................................................. 47 4.7.1 Bewertung der Objektivität.............................................................. 47 4.7.2 Bewertung der Reliabilität................................................................ 47 4.7.3 Bewertung der Validität.................................................................... 49 4.8 Vorgehen zur Auswertung der Hypothesen......................................... 50 4.9 Bestimmung der Cutoff-Werte .............................................................. 50 5 Auswertung Fragebogen.................................................................................. 53 6 Diskussion der Ergebnisse............................................................................... 56 6.1 Handlungen von Fdl ................................................................................ 56 6.1.1 Frühzeitiges Auflösen von Fahrstraßen .......................................... 56 6.1.2 Hilfssperren....................................................................................... 56 6.1.3 Fahrwegprüfungen durch Hinsehen ............................................... 57 6.2 Handlungen von Tf .................................................................................. 58 6.2.1 Wahrnehmung von Signalen ........................................................... 58 6.3 Sicherheitsklima...................................................................................... 59 6.4 Regeln zur Selbstüberwachung ............................................................. 60 6.5 Fehler auf der Wahrnehmungsebene ................................................... 60 6.6 Weitere Analysebereiche ....................................................................... 60 6.6.1 Störungsmeldungen bei Alttechnik................................................. 60 6.6.2 Verstöße im ESTW............................................................................. 61 6.7 Bewertung der Datengrundlage............................................................ 61 7 Fazit .................................................................................................................... 65
109

Space Situational Awareness with the Swedish Allsky Meteor Network

Alinder, Simon January 2019 (has links)
This thesis investigates the use of the Swedish Allsky Meteor Network (SAMN) for observing, identifying, and determining the orbits of satellites. The overall goal of this project is to determine the feasibility of using such a network for Space Situational Awareness (SSA) purposes, which requires identification and monitoring of objects in orbit. This thesis is a collaboration with the Swedish Defense Research Agency (FOI) to support their efforts in SSA. Within the frame of this project, the author developed software that can take data of observations of an object collected from the all-sky cameras of SAMN and do an Initial Orbit Determination (IOD) of the object. An algorithm that improves the results of the IOD was developed and integrated into the software. The software can also identify the object if it is in a database that the program has access to or, if it could not be identified, make an approximate prediction of when and where the object will be visible again the next time it flies over. A program that analyses the stability of the results of the IOD was also developed. This measures the spread in results of the IOD when a small amount of artificial noise is added to one or more of the observed coordinates in the sky. It was found that using multiple cameras at different locations greatly improves the stability of the solutions. Gauss' method was used for doing the IODs. The advantages and disadvantages of using this method are discussed, and ultimately other methods, such as the Gooding method or Double R iteration, are recommended for future works. This is mostly because Gauss' method has a singularity when all three lines of sight from observer to object lie in the same plane, which makes the results unreliable. The software was tested on a number of observations, both synthetic and real, and the results were compared against known data from public databases. It was found that these techniques can, with some changes, be used for doing IOD and satellite identification, but that doing very accurate position determination required for full orbit determination is not feasible. / Detta examensarbete undersöker möjligheterna att använda ett svenskt nätverk av allskykameror kallat SAMN (Swedish Allsky Meteor Network) för att observera, identifiera och banbestämma satelliter. Det övergripande målet med detta projekt är att bestämma hur användbart ett sådant nätverk skulle vara för att skapa en rymdlägesbild, vilken i sin tur kräver bevakning och identifikation av objekt som ligger i omloppsbana. Detta examensarbete är ett samarbete mellan Uppsala Universitet och FOI (Totalförsvarets Forskningsinstitut). Inom ramen för detta projekt har författaren utvecklat mjukvara som kan ta data från observationer av objekt utförda av SAMN och göra initiala banbestämningar av objekten. En algoritm som förbättrar resultaten av den initiala banbestämningen utvecklades och integrerades i programmen. Programmen kan också identifiera satelliter om de finns med i en databas som programmet har tillgång till eller förutsäga objektets nästa passage över observatören om det inte kunde identifieras. Ett annat program som analyserar känsligheten av resultaten av den initiala banbestämningen utvecklades också. Detta program mäter spridningen i resultat som orsakas av små störningar i de observerade koordinaterna på himlen. Det framkom att stabiliteten av resultaten kan förbättras avsevärt genom att använda flera observatörer på olika orter. I detta projekt användes Gauss metod för att göra banbestämningarna. Metodens för- och nackdelar diskuteras och i slutänden rekommenderas istället andra metoder, som Goodings metod eller Dubbel R-iteration, för framtida arbeten. Detta beror mest på att Gauss metod innehåller en singularitet när alla siktlinjer från observatören till objektet ligger i samma plan som varandra vilket gör resultaten opålitliga i de fallen. Programmen testkördes på ett antal olika observationer, både artificiella och verkliga, och resultaten jämfördes med kända positioner. Slutsatsen av arbetet är att de undersökta teknikerna kan, med vissa modifikationer, användas för att göra initiala banbestämningar och satellitidentifikationer, men att göra de väldigt precisa positionsbestämningarna som krävs för fullständig banbestämning är inte genomförbart.
110

Coagency of humans and artificial intelligence in sea rescue environments : A closer look at where artificial intelligence can help humans maintain and improve situational awareness in search and rescue operations

Seger, Johanna January 2019 (has links)
This paper aims to answer the question of how artificial intelligence could help humans maintain and/or improve situational awareness in search and rescue operations at sea, as well as where in such processes artificial intelligence could be incorporated to most efficiently compensate for human vulnerabilities and support human strengths. In order to answer this, a joint cognitive system perspective has been adopted whilst joining in search and rescue practice operations. These operations have been observed and persons participating in them have been interviewed, in order to gather insights about the process and the persons conducting it. The results from these insights coupled with experience with artificial intelligence and automation, show that artificial intelligence could help improve and/or maintain situational awareness by adopting functions which take up unnecessary time from man. According to the joint cognitive system view, these functions should never be solely performed by artificial intelligence however, but in coagency with man; allocated functions should overlap between man and machine. Suggestions have been given regarding which functions in particular an artificial intelligent agent could perform in terms of search and rescue and where these functions occur in the process. None of these suggestions are without man involvement, as they should not be. To summarise, these suggestions include; a UAV equipped with an infrared camera to search large areas quickly, a decision support system equipped with image recognition to analyse images gathered from the UAV, as well as a communication tool which allows for shared search patterns and hotspots between search and rescue units. / WARA-PS

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