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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.
1

Intuitive Mission Handling with Automatic Route Re-planning using Model Predictive Control / Intuitiv uppdragshantering med modellbaserad prediktionsreglering för automatisk ruttomplanering

Andersson, Emma January 2012 (has links)
The system for mission handling in the Gripen fighter aircraft, and in its ground supporting system, consists for example of ways to plan mission routes, create mission points and validate performed missions. The system is complex and for example, the number of different mission points used increases due to changing demands and needs. This master thesis presents suggestions for improvements and simplifications for the mission handling system, to make it more intuitive and more friendly to use. As a base for the suggestions, interviews with pilots from Saab, TUJAS and FMV have been conducted, this is to obtain opinions and ideas from those using the system and have deep knowledge about it. Another possible assistance and improvement is to provide the possibility of on-line automatic re-planning of the mission route in case of obstacles. MPC (Model Predictive Control) has been used to estimate the obstacle’s flight path,and calculate a new route to the next mission point which does not conflict with the estimated enemy’s path. This system has been implemented in Matlab and the concept is demonstrated with different test scenarios where the design parameters (prediction horizon and penalty in the cost function) for the controller are varied, and stationary and moving obstacles are induced. / Systemet för uppdragshantering i stridsflygplanet Gripen, och i dess markstödsystem, består bland annat av uppdragsplanering, skapande av uppdragspunkter och möjligheter att validera utförda uppdrag. Systemet är komplext och exempelvis växer antalet uppdragspunkter med omvärldens ökande krav och behov. Detta examensarbete presenterar förslag till förenklingar och förbättringar i uppdragshanteringssystemet, för att göra det mer intuitivt och användarvänligt. Som grund för förslagen har intervjuer med piloter från Saab, TUJAS och FMV gjorts, för att samla in åsikter och idéer från de som använder systemet och har bred kunskap om det. En förbättring är en möjlighet till online automatisk omplanering av uppdragsrutten vid hinder. MPC (modellbaserad prediktionsreglering) har använts för att estimera den dynamiska fiendens flygväg, och beräkna en ny rutt till nästa uppdragspunkt som inte ligger i konflikt med den estimerade vägen för hindret. Detta system har implementerats i Matlab och konceptet demonstreras med olika testscenarion där prestandaparametrar (prediktionshorisont och straff i kostnadsfunktionen) för regulatorn varieras, och stationära och rörliga hinder induceras.
2

Strategic Forest Management Planning Under Uncertainty Due to Fire

Savage, David William 23 February 2010 (has links)
Forest managers throughout Canada must contend with natural disturbance processes that vary over both time and space when developing and implementing forest management plans designed to provide a range of economic, ecological, and social values. In this thesis, I develop a stochastic simulation model with an embedded linear programming (LP) model and use it to evaluate strategies for reducing uncertainty due to forest fires. My results showed that frequent re-planning was sufficient to reduce variability in harvest volume when the burn fraction was low, however, as the burn fraction increased above 0.45%, the best strategy to reduce variability in harvest volume was to account for fire explicitly in the planning process using Model III. A risk analysis tool was also developed to demonstrate a method for managers to improve decision making under uncertainty. The impact of fire on mature and old forest areas was examined and showed that LP forest management planning models reduce the areas of mature and old forest to the minimum required area and fire further reduces the seral area. As the burn fraction increased, the likelihood of the mature and old forest areas satisfying the minimum area requirements decreased. However, if the seral area constraint was strengthened (i.e., the right hand side of the constraint was increased) the likelihood improved. When the planning model was modified to maximize mature and old forest areas, the two fixed harvest volumes (i.e., 2.0 and 8.0 M. m3/decade) had much different impacts on the areas of mature and old forest when the burn fraction was greater than 0.45%. Bootstrapped burn fraction confidence intervals were used to examine the impact of uncertain burn fraction estimates when using Model III to develop harvest schedules. I found that harvest volume bounds were large when the burn fraction was ≥0.45%. I also examined how the uncertainty in natural burn fraction (i.e., estimates of pre-fire suppression average annual area burned) estimates being used for ecosystem management can impact old forest area requirements and the resulting timber supply.
3

Supporting general aviation pilots during rerouting process due to sudden weather changes

Tokadli, Guliz 21 September 2015 (has links)
General aviation pilots need different types of flight information in order to follow events and the changes related to the aircraft environment while flying. However, general aviation cockpits have some limitations as space to install flight displays to provide flight information beyond the basics to the pilot. Additionally, more sophisticated instrumentation is often expensive to install and maintain. With the development of the tablet-based software applications (such as ForeFlight, WingX Pro7 or Garmin Pilot applications for iPad), general aviation pilots have started to use them instead of paper documentation. These software applications provide essential flight information such as weather forecast, aviation charts, flight documents, etc. Unfortunately, the expectations for their capabilities are changing with the increased demand and popularity of these software applications. Therefore, these flight planning software applications are compared to find what is missing and what have not met the expectation of pilots. First, how the software applications support their decision-making process was described and demonstrated to choose the appropriate flight parameters to change flight path while handling with the other cockpit responsibilities. Finally, these design requirements were validated via HITL tests in a part-task flight simulator. The results provided that the suggested design requirements are found highly useful for both novice and expert general aviation pilots. Specifically, novice general aviation pilots might be able to get visualization to compare real-time weather and weather forecast, and then they might gain experience to improve their success for a in-flight re-planning. On the other side, expert pilots might prefer to use this system if they fly an airspace which they are not familiar to weather features of that region.
4

Strategic Forest Management Planning Under Uncertainty Due to Fire

Savage, David William 23 February 2010 (has links)
Forest managers throughout Canada must contend with natural disturbance processes that vary over both time and space when developing and implementing forest management plans designed to provide a range of economic, ecological, and social values. In this thesis, I develop a stochastic simulation model with an embedded linear programming (LP) model and use it to evaluate strategies for reducing uncertainty due to forest fires. My results showed that frequent re-planning was sufficient to reduce variability in harvest volume when the burn fraction was low, however, as the burn fraction increased above 0.45%, the best strategy to reduce variability in harvest volume was to account for fire explicitly in the planning process using Model III. A risk analysis tool was also developed to demonstrate a method for managers to improve decision making under uncertainty. The impact of fire on mature and old forest areas was examined and showed that LP forest management planning models reduce the areas of mature and old forest to the minimum required area and fire further reduces the seral area. As the burn fraction increased, the likelihood of the mature and old forest areas satisfying the minimum area requirements decreased. However, if the seral area constraint was strengthened (i.e., the right hand side of the constraint was increased) the likelihood improved. When the planning model was modified to maximize mature and old forest areas, the two fixed harvest volumes (i.e., 2.0 and 8.0 M. m3/decade) had much different impacts on the areas of mature and old forest when the burn fraction was greater than 0.45%. Bootstrapped burn fraction confidence intervals were used to examine the impact of uncertain burn fraction estimates when using Model III to develop harvest schedules. I found that harvest volume bounds were large when the burn fraction was ≥0.45%. I also examined how the uncertainty in natural burn fraction (i.e., estimates of pre-fire suppression average annual area burned) estimates being used for ecosystem management can impact old forest area requirements and the resulting timber supply.
5

Project Planning and Re-planning in a Multiple Project Engineer-to-Order Context

Hult, Daniel, Carlsson, Jonathan January 2023 (has links)
Uncertainty and complexity are two factors that make project planning a challenging task. Companies operating in a multiple project Engineer-to-Order environment face an additional dimension of difficulties because of interactions between projects. The changing environment and frequency of unforeseen events increases the difficulty of planning and re-planning and requires flexibility. This study explores how project planning is conducted and what the associated challenges are in a multiple project ETO context. To that end, a case study of a company operating in such a context was investigated using a qualitative approach. In so doing, we shed light on the challenges and provide some insight to mitigate the challenges. The findings suggest that there are challenges related to resource allocation, prioritization, communication and progress updates, and keeping the plan up to date and valid. Practically, the main takeaways are that synergies may be found when leveraging workflow reliability and flexibility as it comes down to deciding when the respective approach is suitable to mitigate the challenges found in the study. In addition, we suggest that prioritization should be integrated into the planning processes to create a better consensus within and among projects. Lastly, we also suggest an additional precondition for releasing work to production.

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