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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

Evaluation of the inventory and accountability practices of common support equipment throughout Pacific and Atlantic Fleets /

McCallister, Frank F. January 1997 (has links)
Thesis (M.S. in Systems Management) Naval Postgraduate School, March 1997. / Thesis advisors, Donald R. Eaton, James G. Taylor, Gordon R. Nakagawa. Includes bibliographical references (p. 81-82). Also available online.
2

PPS5000 Thruster Emulator Architecture Development & Hardware Design

Persson, Robert January 2019 (has links)
This Master's Thesis handles prestudy work and early hardware development that resulted in architectural definitions and prototype hardware of electronic ground support equipment. This equipment is destined to emulate the electric power consumption of the PPS5000 Hall Effect Thruster (HET), for use in satellite end-to-end tests of the all-electric Geostationary Satellite Electra, developed at OHB Sweden AB. The Thruster Emulator (TEM) was defined through a resulting compilation of intricate interdependent components that interface the satellite power system and the thruster, which yielded an architecture development to support some basic predefined emulator requirements. This architecture was then analyzed to form a base-line conceptual function of the emulator system, which incorporates the entire HET functionality. Six primary HET impedances were defined, of which the three most complex impedances were investigated fully. For the primary thruster discharge, research is shown of the complexity of implementing advanced electronic load hardware directly to the satellite's 5kW power system with respect to the transient primary plasma discharge during thruster start up, and with limitations on the electronic load reducing emulator-thruster similarities. Additionally, a fully functional plasma ignition emulator prototype circuit board was built to be used in the final hardware of the TEM to emulate the external HET cathode start-up functionality. Finally, a feasibility study for designing a possible solution for the large PPS5000 electromagnet impedance was performed, resulting in the manufacture of two prototype inductors with unsatisfying performance results according to the design requirements.
3

Mechanical Aspects of Design, Analysis and Testing of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM)

Diaconu, Dumitru 18 March 2014 (has links)
A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.
4

Mechanical Aspects of Design, Analysis and Testing of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM)

Diaconu, Dumitru 18 March 2014 (has links)
A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.
5

Asset Management of Electrical Transportation Systems with Life Cycle Cost Analysis for Ground Support Equipment: Case Study Stockholm Arlanda Airport

Wirén, Hampus January 2018 (has links)
We have come a long way in the pursuit of reducing our carbon footprint from our way of living, bycontinuously development of batteries and charging infrastructure for electric vehicles to decrease thedemand for fossil fuels, improving the overall energy efficiency and to increase awareness of the problemto the population. One of the industries, that during the last decades has undergone vast improvements,is the development of the airplane engines due to increased emission regulations, for the aviationindustry, and to reduce the costs of air travel. Despite tighter regulations, global impact from travellingby air is increasing due to the explosive increase in number of travels and travellers. In order to copewith the situation, it is of course necessary to further develop fuel and emission effective airplanes, butalso to study the whole chain of emission sources correlated to the air transport industry. So, whilewaiting for improved airplanes there are well known emission effective technologies that can beimplemented already today – implement electric vehicles as support vehicles at airports.Today, and throughout history, most of the focus of air travel has been on the airplane itself. This thesis,that was carried out at KTH Royal Institute of Technology during late spring and autumn 2018, didinstead study the support vehicles used in airports. In this thesis, a generic economic model wasdeveloped in order to estimate the costs involved when replacing traditionally vehicles to suggestedelectrically propelled alternatives. To test and support the development of an economic model, a casestudy has been carried out at Stockholm Arlanda Airport. This case study included a field study to thementioned airport, and in combination with interviews with former employees from one of the groundhandling companies that are currently active in the airport. Raw data was collected over the equipmentand vehicles currently in use. This data was used to describe the vehicles purpose, requirements and toensure that the alternative electric vehicles proposed would offer at least the same performance as thetraditional vehicles. The developed generic economic model was modulated with five stages thatrepresented a selection of input parameters. The collected data became a result in itself and was used asinput to three concurrent theses.The results from the five stages presents the costs during an investment period of between of one tofifteen years. One of the most significant result could be seen from Stage V. This stage showed that thecombined cost to replace all vehicles currently used, with either all new diesel vehicles or electricalternative vehicles, are lower for electric vehicles than for diesel vehicles. Another significant resultcould be seen from the investigation of Stage IV, Stage IV-B, were the model was modulated to representthe case of replacing a vehicle. The results showed that the Letter and Cargo procedures, that travel thefarthest and has the highest fuel consumption of the investigated vehicles, had negative costs throughthe whole investment period. This means that the expenses will always be lower when these vehicles arereplaced. The model was validated through a sensitivity analysis, performed on the discount rates,depreciation rates and as well as costs for battery replacement during the depreciation period. / Vi har kommit långt i vår strävan att minska vårt koldioxidavtryck genom vårat sätt att leva, genom attkontinuerligt utveckla batterier och laddningsinfrastruktur för elfordon med syftet att minskaefterfrågan på fossila bränslen, förbättra den totala energieffektiviteten och öka befolkningensmedvetenhet om problemet. En av de branscher, som under de senaste decennierna har genomgått storaförbättringar, är utvecklingen av flygplansmotorer och regler för flygplan. Men eftersom antaletflygresenärer fortsätter att öka årligen krävs ytterligare arbete för att förbättra den totala effektivitetenoch minska det negativa globala avtrycket från flygresor. Medan väntan på att morgondagens flygplanska utvecklas så finns det teknik som redan kan appliceras idag – elfordon.I dag, och genom historien, har det mesta av all fokus för flygresor varit på flygplanen själva. Dettaexamensarbete, som genomfördes på KTH, Kungliga Tekniska Högskolan, under den senare delen avvåren och hösten 2018, utredde istället de fordon som omger ett flygplan, under den tid flygplanet stårstilla på en flygplats. Under denna uppsats utvecklades en generisk ekonomiskmodell, med syftet attestimera kostnaderna att ersätta och använda elfordon istället för de nuvarande fordonen. För attutveckla den ekonomiska modellen genomfördes en fallstudie på Stockholm Arlanda Airport.Fallstudien innehöll en fältundersökning till den nämnda flygplatsen, och i kombination med intervjuermed tidigare anställda från ett av de marktjänstföretag som är verksamma på flygplatsen, insamladesrådata om vilken utrustning och fordon som vid tillfället användes. Denna data användes för att beskrivafordonens syfte, vilka krav som ställs på fordonen. Detta var för att säkerställa att det valda elfordonetkunde utföra uppgiften. Den utvecklade generiska ekonomiska modellen modulerades med fem steg,som representerade vilka indataparametrar som bör väljas. De insamlade uppgifterna blev ett resultat isig och användes som indata till tre samtidiga avhandlingar.Den generiska modellen resultat presenterade kostnaderna från de fem stegen under en varierandeinvesteringsperiod på ett till femton år. Ett av de viktigaste resultaten var från Steg V, som visade attden sammanlagda kostnaden för att ersätta alla de fordon som för närvarande används, med antingenalla nya dieselfordon eller elektriska alternativa fordon, är lägre för elfordon än för dieselfordon. Detandra betydande resultatet kommer från undersökningen av Steg IV, Steg IV-B. I Steg IV-B moduleradesmodellen i syfte att representera scenariot då ett fordon ska ersättas, där Letter och Cargo procedurernavar de som färdades längst och även har den högsta bränsleförbrukningen utav de undersökta fordonen,hade en negativ kostnad under hela investeringslängden. Detta betyder att kostnaderna alltid är lägre,om fordonet ersätts. Modellen har validerats med hjälp utav en känslighetsanalys som utfördes pådiskonteringsräntan, avskrivningssatsen och kostnader för ersättningsbatterier.
6

Design of a vacuum chamber for cathode testing and low power Hall Effect Thrusters : Collaborative project with OHB Sweden AB / Design av en vakuumkammare för katodtestning och Hall Effect Thrusters med låg effekt : Samarbetsprojekt med OHB Sweden AB

Martinez Sanz, Andrea January 2023 (has links)
Testing of hardware to be used in space sometimes involves using vacuum chambers. The need to test hollow cathodes, used as neutralizers for some Electric Propulsion Thrusters, and low power Hall Effect Thrusters at OHB Sweden requires a vacuum chamber to be upgraded. The thesis aims firstly to show the process of adapting the vacuum chamber at OHB to test a heaterless hollow cathode. The requirements of the test included a maximum temperature of a 100 °C in the cathode’s bracket and a pressure inside the chamber around 10¯6 mbar during the test. To accomplish the first, the mounting structure was subjected to a thermal simulation using CREO. Once, the requirement was fulfilled the structure was manufactured and mounted. For the second requirement, a vacuum chamber characterization was done to see the pressure evolution inside the facility. Lastly, the fluid line was designed and mounted in the facility. An upgrade of the current vacuum chamber was deemed insufficient to test low power Hall Effect Thrusters. A comparison between the current vacuum chamber at OHB Sweden and other vacuum chambers designed for this purpose was made. The conclusion was drawn that a new vacuum chamber is necessary. Proposals for the design of a new vacuum facility are presented with particular focus on dimensions, the pump system, sputter protection and thermal protection. / Testandet av hårdvara som ska användas i rymden involverar ibland vakuumkammare. Behovet av att testa hollow cathodes, som används som neutraliserare för vissa jonmotorer, och Hall Effect Thrusters med låg effekt hos OHB Sweden kräver att en vakuumkammare uppgraderas. Avhandlingen syftar först till att redogöra för hur en av vakuumkammarna hos OHB Sweden kan anpassas för att testa en heaterless hollow cathode. Kraven för testet inkluderar en maximal temperatur på 100 °C grader i katodens fäste och och ett vakuum runt 10 ¯6 mbar. En jig designades genom bland annat termisk simulering i CREO. När det termiska kravet ansågs uppfyllas tillverkades och installerades denna jig. För det andra kravet karakteriserades vakuumkammaren med dess vakuumpumpar i syfte att bedöma om dessa kunde uppfylla kravet. Slutligen designades och installerades ett rörsystem som möjliggör matning av bränsle till testobjekten. En uppgradering av nuvarande vakuumkammare bedömdes otillräcklig för att testa Hall Effect Thrusters med låg effekt. En jämförelse mellan nuvarande vakuumkammare på OHB Sweden och andra vakuumkammare designade för detta ändamål gjordes och slutsatsen drogs att en ny vakuumkammare är nödvändig. Förslag på design av ny vakuumkammare presenteras med särkilt fokus på dimensioner, pumpssystemet, sputtingskydd och termiskt skydd.

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