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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.
21

Closing the Road Infrastructure Gap: Analysis of Expenditure Dynamics and Public-Private Partnership Shaping Challenges

Guevara Maldonado, Jose Alberto 26 June 2017 (has links)
The global infrastructure gap has continually widened over the last few decades. Industry reports and academic publications suggest that, in terms of road infrastructure, both advanced and developing economies have not paid sufficient attention to modernize their infrastructure assets. A wider road infrastructure gap signifies that highway conditions have declined because governments have not had enough resources for maintenance and rehabilitation. In the same way, it also indicates that congestion levels have grown and the level of service in most road networks has dropped because public agencies have not had sufficient funds to generate new highways and expand existing corridors. This dissertation, therefore, provided insights into the difficulties associated with improving the existing highway assets and the barriers related to expanding the current roadway capacity through public-private partnerships (PPPs). The research involved three interdependent studies. In the first study, I examined the continuous deterioration of the US highway system through a system dynamics model, which focused on the dynamics of capital investments and maintenance expenditures in the US road infrastructure. The results confirmed that the American highway system is currently stuck in a capability trap. This makes it difficult for the system to improve at the rates required by the country's economic growth. In my second investigation, my attention shifted toward the governance challenges related to building new roads and expanding highway capacity through PPPs. I developed a systems map of governance variables informed by past-published evidence from actual projects. By specifically examining the shaping phase of public-private initiatives, the work uncovered the effects of feedback relationships and interdependencies on PPP feasibility. This offered insights about the relationship between governance mechanisms and successful PPP development. In the third study, I utilized variables and relationships identified in my second investigation to develop a management flight simulator in order to better explain governance difficulties in the procurement phase of PPP projects. The simulator was implemented during an educational exercise with graduate students of civil engineering. By doing so, I confirmed that the simulator has the potential to increase our understanding of PPP procurement processes. Results indicated that the simulation tool was a suitable instrument to explain how government capacity, project uncertainty, and technical complexity influence PPP tendering. Overall, my findings across the three studies illustrate different means to understand why closing the global road infrastructure gap is challenging. Together, the three inquiries indicate that examining the road infrastructure sector as a socio-technical system contributes to improve our understanding of the expenditure dynamics related to existing assets and to enhance our comprehension of the governance challenges associated with developing new roads. / Ph. D.
22

Mixed Reality for Gripen Flight Simulators

Olsson, Tobias, Ullberg, Oscar January 2021 (has links)
This thesis aims to evaluate how different mixed reality solutions can be built and whetheror not it could be used for flight simulators. A simulator prototype was implemented usingUnreal Engine 4 with Varjo’s Unreal Engine plugin giving the foundation for the evaluations done through user studies. Three user studies were performed to test subjectivelatency with Varjo XR-1 in a mixed reality environment, test hand-eye coordination withVarjo XR-1 in a video see-through environment, and test the sense of immersion betweenan IR depth sensor and chroma key flight simulator prototype. The evaluation was seenfrom several perspectives, consisting of: an evaluation from a latency perspective on howa mixed reality solution would compare to an existing dome projector solution, how wellthe masking could be done when using either chroma keying or IR depth sensors, andlastly, which of the two evaluated mixed reality techniques are preferred to use in a senseof immersion and usability.The investigation conducted during the thesis showed that while using a mixed realityenvironment had a minimal impact on system latency compared to using a monitor setup.However, the precision in hand-eye coordination while using VST-mode was evaluated tohave a decreased interaction accuracy while conducting tasks. The comparison betweenthe two mixed reality techniques presented in which areas the techniques excel and wherethey are lacking, therefore, a decision needs to be made to what is more important for eachindividual use case while developing a mixed reality simulator.
23

Image Analysis for Compliant Measurements and Calibration of Visual Projector Systems

Westberg, Daniel January 2023 (has links)
A realistic visualization that enhances a virtually authentic experience is the ambition of any visualization system in a simulator environment. But calibrating and maintaining a high quality visualization system entail large costs, resources and time. Hence, a soft- ware has been developed to facilitate the measuring of three useful metrics that lay the foundation for automatic calibration of visual projector systems. The software and associ- ated method conducts relevant measurements which are compatible with arbitrary surface shapes and can be utilized as an assurance of quality measurement tool. The measure- ments include absolute surface shape, absolute geometry and projector blending zone con- tributions. The implementation decrease manual complexity for users, adds environmen- tal flexibility, increase density of measurement points and is more cost and time efficient then existing methods. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>
24

Prediction of Pilot Skill Level and Workload for Sliding-Scale Autonomous Systems

Nittala, Sai Kameshwar Rao January 2017 (has links)
No description available.
25

A Re-Configurable Hardware-in-the-Loop Flight Simulator

Root, Eric 28 July 2004 (has links)
No description available.
26

VR-flygsimulatorer, för ökad upplevelse och som läroverktyg i flygutbildningar / VR flight simulators, for enhanced experiences and as a pilot training tool

Eliasson, Carl, Hedberg, Alexander January 2017 (has links)
Virtual reality (VR) är ett begrepp som blivit allt mer välkänt de senaste åren. VR kan beskrivas som en datorgenererad virtuell omvärld som användaren omsluts av. VR-miljön upplevs genom människans sinnen såsom syn, hörsel och känsel.Syftet med examensarbetet är att undersöka hur realistisk en kommersiellt tillgänglig VR-flygsimulator upplevs av piloter och undersöka om VR-teknik kan vara ett användbart läroverktyg för t.ex. flygskolor. VR-tekniken har under de senaste åren utvecklats väldigt mycket vilket gjort att många av de implementations svårigheter som VR-tekniken inneburit till stor del lösts. Nya helintegrerade head mounted displays (HMD) med inbyggd kompatibilitet gör att integreringsproblemen nästan helt försvunnit. Eftersom VR-tekniken nu är mer tillgänglig och lätthanterlig ligger det helt rätt i tiden att undersöka hur VR-teknik kan användas inom flygbranschen.Metoden för examensarbetet inleddes med informationsinsamling om VR-teknik och traditionella flygsimulatorer. Utifrån denna information skapades sedan en undersökning som bestod av två delar. Den första delen var ett experiment med en VR-flygsimulator och den andra delen var en intervju som utfördes direkt efter experimentet. Sju stridspiloter deltog i undersökningen.Resultaten av undersökningen visar att VR-flygsimulatorer upplevs som mer realistiska jämfört med traditionella flygsimulatorer. Undersökningen tyder också på att VR-teknik kan vara ett bra läroverktyg om de problem som identifierats lösts på ett tillfredsställande sätt. / Virtual reality (VR) is a rising phenomenon that has skyrocket in popularity the past year. VR is often referred to as a computer generated virtual environment the user gets immersed in. The VR environment is experienced through different types of sensory stimuli.The purpose of this thesis is to examine how realistic a commercially available VR flight simulator is being perceived by real pilots as well as examine if VR technology could be a viable educational tool for flight schools. The motivations of this thesis are the facts that the VR-technology has advanced in a quick phase. Many of the past difficulties with implementing VR technology have been addressed with new fully integrated head mounted displays therefor capability issues are no longer a big problem. Because of the simplicity of new VR-systems it’s a good time to investigate VR uses and how it compares to traditional flight simulator techniques.The method used for the thesis started with collecting information about VR technology and traditional flight simulators. With that information a survey consisting of two parts was created. The first part was an experiment with a VR flight simulator, and the second part was an interview conducted directly after the experiment. Seven jet fighter pilots participated in the survey.Our results show that a VR flight simulator is perceived as more realistic compared to a traditional flight simulator. It is also shown that VR technology could be a good educational tool if some of the issues that were found are resolved or improved upon.
27

Augmenting low-fidelity flight simulation training devices via amplified head rotations

Le-Ngoc, Luan January 2013 (has links)
Due to economic and operational constraints, there is an increasing demand from aviation operators and training manufacturers to extract maximum training usage from the lower fidelity suite of flight simulators. It is possible to augment low-fidelity flight simulators to achieve equivalent performance compared to high-fidelity setups but at reduced cost and greater mobility. In particular for visual manoeuvres, the virtual reality technique of head-tracking amplification for virtual view control enables full field-of-regard access even with limited field-of-view displays. This research quantified the effects of this technique on piloting performance, workload and simulator sickness by applying it to a fixed-base, low-fidelity, low-cost flight simulator. In two separate simulator trials, participants had to land a simulated aircraft from a visual traffic circuit pattern whilst scanning for airborne traffic. Initially, a single augmented display was compared to the common triple display setup in front of the pilot. Starting from the base leg, pilots exhibited tighter turns closer to the desired ground track and were more actively conducting visual scans using the augmented display. This was followed up by a second experiment to quantify the scalability of augmentation towards larger displays and field of views. Task complexity was increased by starting the traffic pattern from the downwind leg. Triple displays in front of the pilot yielded the best compromise delivering flight performance and traffic detection scores just below the triple projectors but without an increase in track deviations and the pilots were also less prone to simulator sickness symptoms. This research demonstrated that head augmentation yields clear benefits of quick user adaptation, low-cost, ease of systems integration, together with the capability to negate the impact of display sizes yet without incurring significant penalties in workload and incurring simulator sickness. The impact of this research is that it facilitates future flight training solutions using this augmentation technique to meet budgetary and mobility requirements. This enables deployment of simulators in large numbers to deliver expanded mission rehearsal previously unattainable within this class of low-fidelity simulators, and with no restrictions for transfer to other training media.
28

Using System Dynamics to Build Electronic Manufacturing Services Plant of Management Flight Simulator

Cheng, Ying-chu 14 February 2008 (has links)
In order to make company work efficiently, managers often divide an enterprise into several functions or departments, such as sales, marketing, human resource, finance and manufacture. However, in this structure, managers would fail to see the wood for the trees. Because each department manager has to be responsible for his own performance, which may easily leads these managers to make decisions that are fit for their department instead of the whole company. Therefore, it¡¦s impossible for companies to make an optimized decision in a dynamic environment. As we enlarge space and time, we can find out that decisions may influence one by another, and the feedback of each decision has a long time delay which makes the manager try to see the wood for the trees even harder. For one manager who tries to show up his performance in a short time will leave the side effect which caused by time delay to other people. What even worse is they can¡¦t predict how much side effect is behind. In this research, we used system dynamics and systems thinking to develop our system dynamics model for the case study. And we developed a MFS(management flight simulator) as a learning tool. Students who manipulate this MFS can enrich their ability to see the wood for the trees. In this case study, we choose a factory which provide electronic product assemble services as a research object. The company was established since AD 1989 until now. After first five years hard working time, it started to grow up stably by keeping changing the product and service. In this industry, success is relied on product quality, price, service and delivery time. Only by making the optimized decision in this competition market can gain better performance. This thesis simulated the case company surface mount technology plant from 1995 to 2006 for 12 years. Students can make different decisions to obtain different equity and capital equipment to evaluate their performance. By different result, simulators can reconsider the structure which is behind the game and their own mental models. After learning from this virtual world, players will find out that their own mental models influencing the final result. From the result and experience, one simulator can accumulate their know-how for the next game. After experiencing this double loop learning process, player will finally learn how to make the best decisions by systems thinking for the real world. Keywords : System Dynamics¡BSystems Thinking¡BDynamic Complexity¡BEnterprise Modeling¡BManagement Flight Simulator¡BSurface Mount Technology(SMT)¡BElectronic Manufacturing Services(EMS)
29

Orientation workspace optimization for a 6-RUS parallel robot / Otimização da orientação no espaço de trabalho de um robo paralelo 6-RUS

Furtado Neto, Clodoaldo Schutel 28 July 2015 (has links)
Made available in DSpace on 2016-12-12T20:25:12Z (GMT). No. of bitstreams: 1 CLODOALDO SCHUTEL FURTADO NETO.pdf: 8051100 bytes, checksum: 8087fda1ce7bcc1fb1f0f63da1457107 (MD5) Previous issue date: 2015-07-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Universidade do Estado de Santa Catarina construiu um simulador de vôo de baseado robô paralelo axissimétrico com 6 DoF (graus de liberdade) que incorpora ambiente de realidade virtual de imersão. Este simulador de vôo apresenta cadeia cinemática 6-RUS que é a segunda arquitetura mais comum para esta aplicação. Robôs paralelos são mecanismos de cadeia fechada que apresentam bom desempenho em termos de precisão, rigidez e capacidade para manipular grandes cargas. Este trabalho tem como objetivo otimizar um robô paralelo 6- RUS para determinar os melhores localizações das juntas ativas ( posição e orientação ) para uma tarefa de simulação de vôo usando um algoritmo PSO (Particle Swarm Optimization) para escapar de mínimos locais e um algoritmo de Ponto Interior para acelerar a procurar pelo ótimo na região indicada por PSO ou seja o algoritmo de Ponto Interior trabalha para encontrar fundo do vale indicado pelo PSO. / The Santa Catarina State University built a flight simulator based on 6-DoF axisymmetric parallel robot which incorporates virtual reality immersion environment. This flight simulator presents 6-RUS kinematic chain which is the second most common architecture for this application. Hunt proposed this chain architecture early in 1983. Parallel robots are closed-loop mechanisms that present good performance in terms of accuracy, rigidity and ability to manipulate large loads. This work aims to optimize a 6- RUS parallel robot to determine the optimal active joints locations (position and orientation) for a flight simulation task using a PSO (Particle Swarm Optimization) algorithm to escape from local minima and an Interior Point algorithm to accelerate the search for the optimum in the region indicated by PSO i.e. Interior Point algorithm work to find bottom of the valley indicated by PSO.
30

Design and evaluation of an educational tool for understanding functionality in flight simulators : Visualising ARINC 610C

Söderström, Arvid, Thorheim, Johanna January 2017 (has links)
The use of simulation in aircraft development and pilot training is essential as it saves time and money. The ARINC 610C standard describes simulator functionality, and is developed to streamline the use of flight simulators. However, the text based standard lacks overview and function descriptions are hard to understand for the simulator developers, who are the main users. In this report, an educational software tool is conceptualised to increase usability of ARINC 610C. The usability goals and requirements were established through multiple interviews and two observation studies. Consequently, six concepts were produced, and evaluated in a workshop with domain experts. Properties from the evaluated concepts were combined in order to form one concluding concept. A prototype was finally developed and evaluated in usability tests with the potential user group. The results from the heuristic evaluation, the usability tests, and a mean system usability score of 79.5 suggests that the prototyped system, developed for visualising ARINC 610C, is a viable solution.

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