12345 1 - 50 of 250
rss atomLink til resultatlisten
Permanent link
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
  • html
  • text
  • asciidoc
  • rtf
  • Arnesson, Erik
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Analysis of sustainable building materials, their possibilities and challenges2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Sweden has as the first welfare state signed the petition of having net zero GHG emissions 2045. The construction industry is a large contributor to Sweden’s current GHG emissions and an action plan signed by several construction companies, including Veidekke, has stated several partial goals and one end goal of a construction industry with net zero emissions 2045. At the same time the demand of new residential houses is high. The choice of material affects the GHG emissions during the entire lifetime, making it a key parameter when planning a construction. 80 % of the emissions during a construction origin from the production of the materials used. The R&D intensity in the construction industry is low and the sector is ruled by a high level of competition and low margins.

    This thesis aimed to investigate more sustainable building materials for bearing parts of multifamily houses, how they compare with conventional materials and challenges facing them. The materials investigated was compared to a reference wall with KPI:s from one construction made by Veidekke. The GHG emission from the reference wall was calculated to be 107 kg CO2-eq/m2wall. The materials were evaluated with the method of Industrial Dynamics to investigate salient and reverse salient properties, lock-ins and important stakeholders. The materials investigated were Cross-laminated timber (CLT) and different types of sustainable concretes. Creating timber concrete hybrids were also explored. CLT currently has a small market share but is a promising material with several beneficial properties. The current development of more sustainable concrete resulted in the investigation of Recycled Aggregates Concrete, Alkali Activated Concrete and the Eco-concrete with reduced amount of cement in favor for limestone powder. A second step was to explore the social and economic challenges for integrating new building materials into the construction industry. As the industry is heavily project based, the timeframe and lack of budget to explore new options acts as barrier. The processes also tend to be repetitive. As of now the industry has made itself path dependent to concrete in a large extent. However, the social acceptance towards CLT is rising and making sustainability a strategic business goal is becoming more important to appeal to the customers. Interviews at Veidekke showed the rising interest of mixing timber and concrete, but also the difficulties of pushing development forward in the industry. 

    The materials and their KPI:s resulted in the further investigation of CLT and Eco-concrete. By stating the salient and reverse salient properties of the materials further analysis could be done. CLT showed the greatest reduction of GHG emissions due to the embodied carbon resulting in a negative GHG emission of -66.2 kg CO2-eq/m2wall. In addition to this the construction time and several other beneficial properties were found. The reduction of GHG emissions of the Eco-concrete is great too, about 50 % comparing with the concrete used in the reference wall. As a concrete the Eco-concrete should also face less barriers as the industry is familiar with the product. Further analysis with tools from industrial dynamics showed the importance of creating incitements for developing the knowledge of a sustainable construction industry. Results also showed that new networks between the manufactures and the building sector is of essence to find and use new materials. Timber and concrete industries have the main responsibility of developing new and more sustainable products. The building sector also have a responsibility of choosing sustainable options. Advocating a diversity of solutions will create a more robust and resilient industry with fewer lock-ins and path dependencies occurring today. 

    The key stakeholders identified from stakeholder mapping was the business developers, the department of purchase, the timber and concrete industry and lastly the customers. Business developers need to pursue projects with clear and tough goals of sustainability. This will increase the chance of succeeding. The department of purchase need to have incitements for mapping sustainable materials and the ability to explore new subcontractors. The results of the analysis show that not a single innovation will solve the goal of having a construction industry with net zero emissions 2045. The key innovation opportunities for CLT is to develop a standardization and modularization comparable with the concrete industry. Improving the fire safety of CLT is also of essence and the development of fire proofing plasterboards and insulation could be a solution. Further research on modified design mixing and the usage of pozzolanic materials like limestone in concrete is also an important way forward. Constructing timber concrete hybrids have also raised great potential both in the literature, analysis and from the interviews to simplify the integration of timber into the market.

  • Govea Buendia, Jose Agustin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Can Mexico meet the renewable energy targets under the emission trading scheme?: An analysis of the Mexican electricity framework2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Mexican power sector has started an ambitious transition since 2013 to open the sector to private investors. Constitutional amendments envisage a cleaner electricity sector, setting goals for renewable energy  share  in  the  electricity  mix  respectively  35%  by  2024,  40%  by  2035,  and  50%  by  2050.  Simultaneously, Mexico has set targets to reduce GHG emissions including among others, the electricity sector. To achieve these goals, the Mexican government has recently announced the implementation of a mandatory Emission Trading Scheme (ETS). The study investigated the impact of adopting the ETS from 2017 to 2050 in the Mexican electricity sector.

    The study used Open Source Energy Modeling System (OSeMOSYS) in order to build a model of the current Mexican electricity sector. Ten different scenarios were created to explore the evolution of the electricity industry in the country under an ETS (e.g. emissions limited and penalized). The conditional and  unconditional  Intended  Nationally  Determined  Contributions  (INDC)  adopted  by  Mexico  were  considered to replicate the cap on emissions. The unconditional INDC implied 22% less emissions, whereas the conditional INDC suggested 50% less emissions. Furthermore, five different penalties on emissions were applied (2.5 USD/tCO2eq, 7.5 USD/tCO2eq, 15 USD/tCO2eq, 30 USD/tCO2eq, and 50 USD/tCO2eq).

    The results suggest that when the ETS is not adopted the emissions continuously increase until 2050, and the renewable penetration targets are not achieved. Additionally, under a 22% less emissions cap  the  renewable  penetration  targets  are  not  achieved  in  any  scenario,  however the GHG reduction  target is attained in all the scenarios, both by 2031 and until 2050. Under a 50% less emissions cap, the GHG reduction targets are achieved; nonetheless, the renewable penetration targets are only achieved in 2024 and 2035, but not in 2050.

    Finally, according to the simulations, the Mexican electricity sector showed a high level of dependency on conventional technologies fueled by natural gas (i.e. combined cycle and gas turbine power plants) by 2050. Solar PV had the largest power generation share, followed by onshore wind power. Only under a 50% less emissions cap, offshore wind power penetrated the Mexican electricity sector.

  • Sani, Lorenzo
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Pathways for a Sustainable Treatment of Biomass Residue at Palm Oil Mills: the Case of Indonesia2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Utöver att palmoljeindustrin producerar den mest konsumerade vegetabiliska oljan i världen skapar den också en betydande mängd biomassavfall. Det finns consensus över att användning utav detta biomassanavfall för energiproduktion har en betydande potential. Men palm oil mill effluent (förkortas POME efter akronym av palm oil mill effluent), restprodukten som är ansvarig för dem största växthusgasutsläppen i palmoljeproduktion, tas om hand på ett ohållbart sätt. Metanutsläpp från POME-nedbrytning, i en konventionell palmolja kvarn, ansvarar för mer än hälften av utsläppen av växthusgaser i produktionsprocessen (exklusive förändring av markanvändningen). Detta arbete undersöker alternativ för att eftermontera bioraffinaderier i indonesiska palmolja kvarnar som kan effektivt utnyttja POME för att skapa förädlade produkter (t.ex. el, kompost och pellets) och samtidigt minska miljöpåverkan. I detta arbete presenterar författaren en litteraturöversikt av kommersiellt mogna behandlingstekniker för POME och biomassavfall samt framhäver de mest lovande metoderna. Därefter skapas olika bioraffinaderikoncept genom att kombinera de mest intressanta teknikerna med syfte att maximera intäkter och sociala effekter samtidigt som minska miljöpåverkan. För varje bioraffinaderikoncept utförs en hållbarhetsbedömning med hjälp av olika serier av indikatorer som representerar ekonomiska, miljömässiga och sociala konsekvenser. En multikriterieanalys tillämpas för att kombinera i ett enda index den information som erhållits genom hållbarhetsbedömningen. Denna metod möjliggör identifiering av lösningen som erbjuder den bästa avvägningen samtidigt som man integrerar i beslutsprocessens synvinklar från alla parter. Resultaten visar att det är möjligt att undvika metanutsläpp från obehandlad POME på ett ekonomiskt lönsamt sätt samtidigt som man genererar positiva sociala konsekvenser. Utsläppsminskningen av de föreslagna bioraffinaderikoncepterna visar besparingar från 67% till 109% jämfört med det konventionella systemet. Vidare visade sig att alla föreslagna bioraffinaderikoncept var ekonomiskt och socialt hållbara. De bästa resultaten har erhållits av ett bioraffinaderikoncept som producerar el från metan som tagits från POME-nedbrytning för att producera högkvalitativa produkter som pellets från biomassrest och rå kärnolja. Samma lösning visade sig vara bäst också för off-grid palmolja kvarnar, trots att de tenderar att fördra lösningar med enklare design. Sammanfattningsvis visar denna studie att bioraffinaderikoncept är en möjlighet för bruksägare att följa de strängaste miljöreglerna samtidigt som öka vinsten och skapa positiva social påverkan.

  • Hosseini Moghaddam, Seyed Mazyar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Designing battery thermal management systems (BTMS) for cylindrical Lithium-ion battery modules using CFD2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Renewable Energies have the capability to cut down the severe impacts of energy and environmental crisis. Integrating renewable energy generation into the global energy system calls for state of the art energy storage technologies. The lithium-ion battery is introduced in this paper as a solution with a promising role in the storage sector on the grounds of high mass and volumetric energy density. Afterward, the advantages of proper thermal management, including thermal runaway prevention, optimum performance, durability, and temperature uniformity are described. In particular, this review detailedly compares the most frequently adopted battery thermal management solutions (BTMS) in the storage industry including direct and indirect liquid, air, phase-change material, and heating.

    In this work, four battery thermal management solutions are selected and analyzed using Computational Fluid Dynamic (CFD) simulations for accurate thermal modeling. The outcome of the simulations is compared using parameters e.g. temperature distribution in battery cells, battery module, and power consumption. Liquid cooling utilizing the direct contact higher cooling performance to the conventional air cooling methods. However, there exist some challenges being adopted in the market. Each of the methods proves to be favorable for a particular application and can be further optimized.

  • Styfberg Lundqvist, Anna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Wendel, Olivia
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Cirkul¨ar ekonomi inom produktion av solcellssystem2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Solcellstekniken är den mest lovande metoden för utvinning av förnyelsebar energi. Marknaden för solceller växer kraftigt och det är därför av stor vikt att solcellsindustrin utformas på ett hållbart sätt. I detta kandidatexamensarbete kommer vi att utreda hur solcellsindustrin kan anpassas för en cirkulär ekonomi. Fokus har valts till hur en producent av solcellsmoduler, och hur en montör av solcellssystem, kan anpassa sin verksamhet för att implementera cirkulär ekonomi. Arbetet har utförts som en litteraturstudie av solcellsproduktion. Montering av solcellssystem har kartlagts genom intervjuer med VDn på Susen AB som är en svensk montör av solcellssystem. I resultatet diskuteras vilka åtgärder som behöver vidtas inom solcellsproduktionen och hos en montör av solcellssystem för att The Ellen MacArthur Foundation’s tre principer för en cirkulär ekonomi ska uppfyllas. Resultatet visar att det viktigaste arbetet för att uppnå en cirkulär ekonomi ligger i hanteringen av förbrukade solcellssystem. Återvinningsstationer specialiserade på hantering av uttjänta solceller behöver utformas. Kiselutvinning är den process som kräver mest energi i produktionen av solceller, varför återvinning av kisel från uttjänta solceller är av stor vikt för att cirkulär ekonomi ska råda. Problemet med etablering av ett återvinningssystem för solcellsmoduler är att eftersom den tekniska livslängden för solceller är så lång finns det i dagsläget en för liten mängd uttjänta solceller för att någon aktör ska finna det lönsamt att bedriva en sådan verksamhet. Den största svårigheten med att implementera cirkulär ekonomi inom solcellsindustrin är faktumet att leveranskedjan är väldigt spridd. För att möjliggöra cirkulär ekonomi behöver det därför utformas samarbeten mellan de olika aktörerna, förslagsvis genom en branschstandard för hur produktion, montering och hantering av uttjänta solcellssystem ska fungera i enlighet med den cirkulära ekonomins principer.

  • Nyari, Judit
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Techno-economic feasibility study of a methanol plant using carbon dioxide and hydrogen2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In 2015, more than 80% of energy consumption was based on fossil resources. Growing population especially in developing countries fuel the trend in global energy consumption. This constant increase however leads to climate change caused by anthropogenic greenhouse gas (GHG) emissions. GHG, especially CO2 mitigation is one of the top priority challenges in the EU. Amongst the solutions to mitigate future emissions, carbon capture and utilization (CCU) is gaining interest. CO2 is a valuable, abundant and renewable carbon source that can be converted into fuels and chemicals. Methanol (MeOH) is one of the chemicals that can be produced from CO2. It is considered a basic compound in chemical industry as it can be utilised in a versatility of processes. These arguments make methanol and its production from CO2 a current, intriguing topic in climate change mitigation.

    In this master’s thesis first the applications, production, global demand and market price of methanol were investigated. In the second part of the thesis, a methanol plant producing chemical grade methanol was simulated in Aspen Plus. The studied plants have three different annual capacities: 10 kt/a, 50 kt/a and 250 kt/a. They were compared with the option of buying the CO2 or capturing it directly from flue gases through a carbon capture (CC) unit attached to the methanol plant. The kinetic model considering both CO and CO2 as sources of carbon for methanol formation was described thoroughly, and the main considerations and parameters were introduced for the simulation. The simulation successfully achieved chemical grade methanol production, with a high overall CO2 conversion rate and close to stoichiometric raw material utilization. Heat exchanger network was optimized in Aspen Energy Analyzer which achieved a total of 75% heat duty saving.

    The estimated levelised cost of methanol (LCOMeOH) ranges between 1130 and 630 €/t which is significantly higher than the current listed market price for fossil methanol at 419 €/t. This high LCOMeOH is mostly due to the high production cost of hydrogen, which corresponds to 72% of LCOMeOH. It was revealed that selling the oxygen by-product from water electrolysis had the most significant effect, reducing the LCOMeOH to 475 €/t. Cost of electricity also has a significant influence on the LCOMeOH, and for a 10 €/MWh change the LCOMeOH changed by 110 €/t. Finally, the estimated LCOMeOH was least sensitive for the change in cost of CO2. When comparing owning a CC plant with purchasing CO2, it was revealed that purchasing option is only beneficial for smaller plants.

  • Hughes, David
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Decarbonization in European Public Transit: A Well-to-Wheels study of the bus fleets of Barcelona, Stockholm and Warsaw2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    It is a current objective in many cities to reduce GHG emissions and energy consumption in their public transit fleets. Specifically, the electrification of bus lines are being considered for their reduction potential and alignment with ’Smart City’ trends. This thesis aims to examine this in the context of the pub-lic bus fleets of Barcelona, Stockholm and Warsaw. Past and present fleet data was compiled, along with future plans in order to form the basis for a Well-to-Wheel analysis for each city’s fleet. The trend suggests that the carbon intensity of the energy mix is a critical component in determining just how effective bus fleet electrifcation is in reducing emissions and consumption. There is also evidence of future emissions being pushed upstream, showing local reductions but lacking in overall reductions. Municipalities often have direct influence over their public transit system, and hopefully the informa-tion presented in this thesis can be used to help them make more informed decisions as to what the results of their plans will be, in order to develop their cities in line with a truly smart and sustainable model.

  • Falkenstrand, Johanna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Lundström, Sara
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Svensk textil- och konfektionsindustri: en analys av branschens framtidsutsikter2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Arbetets huvudmål är att analysera förutsättningarna för en återhämtning av den svenska textil- och konfektionsindustrin (TEKO-industrin). TEKO-industrin var under större delen av 1900-talet en betydande industrigren i Sverige. Under framför allt 1970-talet genomgick branschen förändringar och mötte stora motgångar vilket resulterade i att den nästan helt försvann. Sverige förlorade i och med krisen den kompetens som under årtionden byggts upp och idag är just bristen på kompetens ett betydande problem för branschen. En annan utmaning som branschen står inför är skillnaden i produktionskostnad som uppstår som följd av skillnad i löneläge, miljölagar, tillgänglighet och pris på råvaror och andra fasta kostnader. En växande trend är att företag väljer att flytta hem sin produktion från utlandet, så kallad reshoring. Löneläget är på väg upp i utvecklingsländer och dagens konsumenter efterfrågar i större utsträckning kvalitet, flexibilitet och social och miljömässig hållbarhet. Företagen kan genom att flytta hem sin produktion korta sina ledtider, öka flexibiliteten i värdekedjan och samtidigt bygga sitt varumärke. Frågan är om detta är applicerbart på textilindustrin? De företag som gynnas av att ha produktion i Sverige är framför allt producenter av som tydligt nischade produkter där en hög automatiseringsgrad av produktionen är möjlig, men inte ens dessa finner det självklart att i framtiden ligga kvar i Sverige. Arbetet har lett oss till slutsatsen att den typ av TEKO-industri som i framtiden kan komma att bli stark i Sverige inte är den klassiska TEKO-industrin som en gång flyttade till låglöneländer. Vi kan, om rätt satsningar görs, komma att se högautomatiserad tillverkning av innovativa tekniska textilier. Det finns även potential i att utnyttja pappersverkens produktionsanläggningar för att producera biomassa som i sin tur kan förädlas till cellulosabaserade textilier.

  • Agarwal, Rohit
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    User Interface Design of Head-Up Display Using Scenarios: An Early Stage Innovation Project at Bombardier2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Head-up display (HUD) är en beprövad teknik inom flyg och bil, vilken gör det möjligt för piloter och förare att få tillgång till information utan att uppmärksamheten avleds från omvärlden. Liknande fördelar kan uppnås genom installation av HUD i tåg.

    Syftet med denna studie är att utveckla ett användargränssnitt för HUD baserat på European Rail Traffic Management System (ERTMS). HUD kommer att vara en extra säkerhetsfunktion för tågen för att förhindra förare från att skifta fokus mellan instrumentpanelen och omgivningen, vilket leder till minskad förareutmattning och bättre observation av spåren framåt. Scenario Based Design-metoden har använts för att genomföra projektarbetet och i rapporten diskuteras metodens  fördelar och begränsningar. Användningen av scenarier har gjort det möjligt för designteamet att på djupet förstå de situationer som förarna står inför samt  har hjälpt till att under workshops få en bättre förståelse för drivrutinerna.

    Dessutom har rekommendationer för hårdvara, installation och framtida arbete beskrivits för fortsatt genomförande av projektet.

  • Razzetti, Elisa
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Potential for Seasonal Electricity Storage in Borehole Thermal Energy Stores with Heat Pumps2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In Sweden, there is a substantial increase in renewable power generation that affects the elec-tricity market. At the residential, PV diffusion spreads in the last years due to price drop, while use of heat pump is consolidated. This thesis aims to evaluate the technological potential and economic value of seasonal storage of electricity in a thermal medium using boreholes and heat pump for a multi-family house in Sweden in a context of high renewable market.

    An existing GSHP-PV system model is implemented in TRNSYS with the addition of an in-line heater on the boreholes circuit. Its function is to heat the borehole field during PV peaks or low electricity price. The performance of the system is evaluated in terms of renewable and consumption impact with Self-Consumption, Solar Fraction and Seasonal Performance Factor, while Total Life Cycle Cost defines the economic feasibility of the system.

    In order to estimate several price scenario, an electricity market model is developed and applied to forecast the hourly electricity price in future in Sweden with high wind and solar penetra-tion.

    The results suggest that the configuration studied does not benefit from seasonal storage of elec-tricity. Since the increase of electric demand due to the borehole heater, self-consumption is generally improved despite solar fraction depends greatly from the only use of PV over produc-tion or grid prices. Seasonal peak shift and SPF improvement are not demonstrated, although there is an increase of TLCC. This leaves the system without storage the most profitable, despite the use of electric boilers or heat pumps at the borehole heater.

  • Asp Birgersson, Olivia
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Törnered, Elisabet
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Design av tvättmaskiner för ökad cirkularitet2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Med dagens ekonomiska tillväxt stiger levnadsstandarden i samhället samtidigt som konsumtionstakten ökar, vilket leder till att jordens resurser förbrukas i ett allt högre tempo. Till följd av detta börjar riskerna med den traditionella, linjära ekonomin uppmärksammas i allt högre grad, då den utgår från att tillgången till dessa resurser är obegränsad. Dessa utmaningar har lett till att idén om den cirkulära ekonomin växt fram, vilken syftar till att skapa ett långsiktigt hållbart kretslopp. Tanken är att komponenter och material bör hållas i stängda loopar och att de innersta ska prioriteras. I detta arbete benämns dessa loopar underhåll och reparation, återanvändning, återtillverkning och återvinning. Syftet med arbetet är att utreda hur koncepten inom cirkulär ekonomi lämpligast appliceras på tvättmaskiner. För att åstadkomma detta behandlas tre frågeställningar utifrån vilka en slutsats gällande hur tvättmaskiner ska designas för en cirkulär ekonomi kan dras. Dessa frågeställningar innefattar vilka designparametrar hos tvättmaskinen som har störst påverkan på möjligheterna att öka cirkulariteten, hur looparna inom cirkulär ekonomi tillämpas idag och varför, samt vilka incitament och hinder som finns för ökad cirkularitet hos tvättmaskinen. Strategin för utförandet var att kombinera teori med empiri genom en inledande litteraturstudie följd av fyra intervjuer med olika aktörer i värdekedjan: Miele, Electrolux, Hushållsservice Söderort AB och El-Kretsen. Vår rekommendation för ökad cirkularitet är att designa tvättmaskiner som är enkla att demontera, består av väl valda material och är konstruerade för lång livslängd. Vidare bör det också finnas möjlighet till förlängning av livslängd såväl som till uppgradering av komponenter och mjukvara. Samtliga av dessa designlösningar är grundläggande för att öka resurseffektiviteten, varför vi inte uteslutande kan rekommendera en enskild av dem. Även modularisering utvärderas som designlösning, men en eventuell rekommendation skulle kräva djupare analyser än detta arbete behandlar. För att ökad cirkularitet ska vara realistiskt krävs dessutom ytterligare åtgärder som inte avser produktens design eftersom satsningar i praktiken förutsätter att lösningarna uppmuntras med finansiella incitament. Exempelvis skulle dessa kunna genereras till följd av en främjande lagstiftning, forskningsframsteg och ökad efterfrågan hos konsumenter.

  • Ramirez Gomez, Camilo
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    A techno-economicGIS-based model for waste water treatment and reuse feasibility in the North Western Sahara Aquifer System2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Water security represents a main challenge in the quest for sustainable development and stability worldwide. Often, such security is closely linked with the demand of water for agricultural irrigation, as it repre-sents the major share of human water withdrawals. The North Western Sahara Aquifer System (NWSAS), is a large aquifer system spreading through three North African countries: Algeria, Tunisia and Libya. It is formed by two superposed groundwater reservoirs, constituting the main sources of fresh water access in the region. To cope with the water demand and alleviate water resources exploitation, Treated Wastewater (TWW) is emerging as a promising solution for the region. This master thesis focused on the development of a GIS-based methodology to asses the techno-economic feasibility of wastewater reclaim, treatment and reuse for crop irrigation in the NWSAS region, considering groundwa-ter quality and depletion, electrical energy requirements and Levelised Cost of Water (LCOW) as main assessment parameters. Such model enables the evaluation, under different scenarios, of the impact that new policies, technologies and measures can have in the overall system.

    Nine wastewater treatment technologies were analysed, under eight dif-ferent scenarios. The scenarios were constructed based on population water requirements per capita and the behaviour of farmers towards different irrigation water price regimes. The least-cost technologies found, presented a tradeoff between the wastewater treatment capac-ity and the technology chosen, which approximates to the behaviour found in reality. The outcomes of the analysis, evidenced the current medium-to-high stress of the groundwater resource, which is trending to worsen. Moreover, the reuse of treated wastewater in agricultural irrigation, showed to be a viable option for reducing the water stress of the basin. However, to preserve the water resource, measures as better water pricing mechanisms, management strategies to improve water productivity and adoption of more efficient irrigation schemes may be needed. Furthermore, the energy-for-water needs were evaluated. Pumping energy represents by far the major user of electrical energy in the region and the treatment and reuse of waste water, showed to be useful to reduce the dependency on pumped resources, reducing as well the energy-for-water needs. Moreover, the effect of changes in salinity content and depth to groundwater levels, showed substan-tial effects on the energy requirements for desalination and pumping respectively, which can jeopardize the economic sustainability of the agricultural practice in the basin.

  • Bremström, Maria
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Stipic, Susanne
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Återtillverkning av fordonskomponenter: En komparativ studie av den svenska marknaden2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Den klassiska linjära produktionsmodellen har länge varit dominerande. Denna typ av produktion bygger på en ständig tillgång av ändliga råvaror som förädlas, konsumeras och sedan kasseras. I takt med att råvarureserverna minskar och hållbar produktion blir allt viktigare har dock olika metoder för att återanvända material och produkter börjat uppmärksammas. Detta syns särskilt tydligt inom fordonsbranschen. Där är återtillverkning, alltså återställande av en uttjänt produkt till nyskick, ett växande fokus för både originaltillverkare och oberoende aktörer (så kallade fristående återtillverkare). Syftet med detta arbete har varit att undersöka återtillverkning av fordonskomponenter på den svenska marknaden. Detta har skett genom undersökning av aktörer inom återtillverkningsindustrin. Dessutom har en komparativ studie av två återtillverkande företag, Volvo Powertrain i Flen och Borg Automotive, utförts. I arbetet jämfördes även de svårigheter för återtillverkning som framgick i den teoretiska referensramen med de svårigheter som återtillverkare upplever i praktiken. Resultatet av arbetet visade att återtillverkning inte är ett utbrett fenomen på den svenska marknaden, men de intervjuade aktörerna har en positiv inställning till återtillverkning och ser det som en växande industri. De hinder som finns för ökad återtillverkning är främst de som identifierats i teorin. Dessa är omfattande lagerhållning, problem med återtagande av uttjänta komponenter och svårigheter med att automatisera återtillverkningsprocessen. Det framgår dessutom att originaltillverkare och fristående återtillverkare har olika förutsättningar och står inför olika problem. Vidare innebär höga inträdesbarriärer svårigheter för nya aktörer att etablera sig inom återtillverkningsbranschen. De juridiska incitamenten är i dagsläget svaga, de starkaste incitamenten för företag att börja återtillverka är i stället ekonomiska. Ett problem som inte framgick av teorin, som originaltillverkare upplever, är matchning av utbud och efterfrågan. Sammanfattningsvis stämmer teori och praktik generellt överens vilket visar på att återtillverkning är väl förstått inom den akademiska litteraturen. De problem med att matcha utbud och efterfrågan bör dock undersökas närmare då det saknas teoretisk bakgrund till detta problem. Det finns en framtidstro för återtillverkning och de inblandade aktörerna arbetar aktivt för att främja återtillverkning och bemöta de problem som finns i dagsläget.

    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Ledtidsreduktion med hänsyn till kapitalbindning: Vägen mot minskad ledtid och kapitalbindning i Lantmännen Cerealias pastafabrik2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    På grund av rådande livsmedelstrender har efterfrågan på premiumvaror, som ekologiska och kolhydratfattiga livsmedel, ökat. Trenderna sätter tryck på livsmedelsföretag att erbjuda ett brett utbud av produkter. Detta får till följd att behovet av effektiva försörjningskedjor ökar samtidigt som det bundna kapitalet behöver minskas för att få ökad lönsamhet. För att identifiera var slöserier som driver upp ledtiden finns i ett produktionsflöde, kan värdeflödesanalys användas. Genom användning av värdeflödesanalys kan värdeskapande tid ställas mot icke värdeskapande tid för att upptäcka moment som inte tillför värde för kunden utan endast driver upp kostnader. Analys av dessa moment kan leda till identifiering av möjligheter för reduktion av kapitalbindning i form av minskade nivåer av produkter i arbete och lager. Kapitalbindning kan även reduceras genom ABC-klassificering av artiklar. Syftet med detta kandidatexamensarbete är att undersöka reduktion av ledtider i Lantmännen Cerealias pastafabrik med hjälp av värdeflödesanalys. Utöver detta undersöks hur kapitalbindningen kan reduceras samtidigt som ledtidsreduktionen genomförs. Slutligen ABCklassificeras produkterna. Dels för att minska kapitalbindningen, dels för att underlätta vid fluktuationer i efterfrågan hos fabriken. Slutsatsen svarar på om det är möjligt att reducera ledtiden i fabriken samtidigt som en reduktion av kapitalbindning görs. Värdeflödesanalys visade sig vara ett bra verktyg för att identifiera eventuella slöserier och förbättringsmöjligheter i produktionen. Svårigheten med analysen i detta fall låg i att finna korrekta siffror till analysen eftersom data för detta mottogs i sin helhet och ej mättes upp i fabriken. ABC-klassificeringens valda parametrar visades lämpliga då uppdelningen blev tydlig. Denna tog hänsyn till problem både rörande efterfrågefluktuationer och kapitalbindning. Slutsatsen drogs att om lagerhållningen styrs enligt denna uppdelning kan kapitalbindningen minskas samtidigt som företaget enklare kan möta fluktuationer i efterfrågan. Den reducerade ledtiden som värdeflödesanalysen resulterade i, gav effekten att medel-PIAnivån i produktionen kunde minskas. Detta skulle kunna ske genom att minska mellanlagringstiden i silos. Möjlighet saknas att på kort sikt reducera medel-PIA-nivån till den kritiska volymen av PIA, dock leder den möjliga minskningen till en reduktion av kapitalbindning. Den viktigaste slutsatsen som dras är att reduktion av ledtid ofta har en positiv inverkan även på kapitalbindningen. I detta fall visade sig lagerhållning ha stor betydelse för reduktion av både ledtid och kapitalbindning. Att reducera lagringstiden i färdigvarulagret ger större effekt på kapitalbindningen än en reduktion av mellanlagringstiden i silos då produktens värde är större i detta skede

  • Fournis, Camille
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Flygdynamik.
    Study of tip clearance flows2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The tip leakage vortex is responsible for the generation of stagnation pressure losses inside the compressor along with the outbreak of rotating stall and surge. The current paper analytically proved that a part of the losses is proportional to the vortex circulation squared. The evolution of this circulation has been investigated as part of a parametric study which tested several clearance heights.

    The work consists in adopting a simplified single blade configuration to study the physics of the flow by means of wind tunnel experiments and numerical calculations. Upon visualising the main features of the flow, a model based on the study of jet in crossflows was implemented to describe the tip clearance flow for small gap sizes. For big gaps, the flow is assumed to behave as an isolated wing tip vortex which circulation is easily computed by the so called lifting line theory. The main vortical structures highlighted by the topology of the flow justified the use of the model of a jet in crossflow for small gap sizes. This model was challenged by experimental and numerical data and proved to well predict the evolution of the clearance vortex circulation for an increasing clearance height although some numerical results remain further away from the model.

  • Disputas: 2019-10-26 00:00
    Betts, Abdul
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.).
    Mortgage funds: Examining the emergence of new mortgage finance methods in Sweden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Recent reports from the Swedish Financial supervisory authority and the Swedish competition agency suggest that while bank profitability is high in Sweden, the dominant position of a handful of actors have created a situation where consumers are left displeased. The mortgage market has been highlighted as one of the most concerning markets and yet, gross margins on mortgages are reaching record levels. However, as of recent, two new actors have announced their intention to challenge the incumbent banks by importing a new mortgage financing method from the Netherlands. The financing model is rooted in the creation of a mortgage fund and could have several particularly interesting implications for the Swedish mortgage market. Thus, the purpose of this thesis is to examine mortgage funds and its ability to change current market structures in Sweden. By examining the relationship between return on assets and cost-to-income ratios for Swedish mortgage brokers during 2011-2017, the level of competition on the Swedish mortgage market is estimated and examined in relation to the introduction of mortgage funds. It is found that the introduction of mortgage funds in Sweden have caused a structural shift of the market by altering the value-chain of Swedish mortgages. The conclusion of this study is that mortgage funds, if managed correctly, can be a helpful addition to the Swedish mortgage market by bolstering competition and diversity.

  • Kazi-tani, Zakaria
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Simulation of Hardening of the MahanaKhon Tower Mat Foundation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cement hydration is the result of a series of simultaneous chemical reactions occurring during the production of concrete. An excessive amount of heat is generated, which consequently may give rise to thermal stresses and cause early age cracks in concrete that may affect its structural integrity, and load bearing capacity. Incorporating fly ash into the concrete mixture has shown to be an efficient method to reduce the temperatures developed during early age hydration, especially for massive concrete structures. Fly ash does additionally affect the concrete's development of compressive strength, tensile strength and Young's modulus.

    The MahanaKhon tower's mat foundation is divided into 14 layers, with fly ash incorporated in the concrete mix. A finite element model was developed of the mat foundation with COMSOL Multiphysics to simulate the developed temperatures and thermal stresses during curing. The simulations were carried out as parametric studies with different strain reference temperatures. The simulated temperatures were compared with existing temperature measurements that were conducted in three different elevations in each concrete layer. The result of the temperature analyses showed that the measured temperatures were generally larger than the simulated ones, which may have been the result of the numerical model's heat conductivity and convective heat transfer coeffcient not reflecting the actual case. Furthermore, the numerical model did not take into account the effects of solar radiation, which would most likely have increased the temperature of the concrete. The maximum simulated temperatures were mostly found in the center level of the concrete, followed by the lower level, and the lowest at the top. It was also observed that the maximum temperatures in some of the mat foundation layers could exceed 70 °C, which is generally considered high since the risk of delayed ettringite formation may arise. The large temperature is partially a result of not using cooling methods, such as cooling pipes, but also due to the high initial and ambient temperatures.

    The result of the thermal stress analyses showed that no tensile stresses arose when the strain reference temperature, Tref, was specified to 30 °C, corresponding to the mean ambient temperature. This is due to the concrete temperature not falling below Tref, and the concrete will therefore be in expansion and only be subject to compressive stresses. Increasing Tref to 50 °C, which was considered a reasonable estimation, resulted in developed tensile stresses in all mat foundation layers, where the majority of the mat foundation layers showed a risk of superficial surface cracks. The maximum tensile stresses were found at the final time of the simulations, which was expected, since the temperatures were at their lowest as a result of removing the curing insulation. Finally, setting Tref to 70 °C, corresponding to the maximum temperature during hardening, increased the induced tensile stresses considerably, due to the large temperature gradient between Tref and the concrete temperature. The maximum stresses were, as expected, located at the top level and caused by internal restraint. The second largest tensile stresses were found in the center level, also subject to internal restraint. The lowest tensile stresses were located in the lower level, subject to external restraint.

  • Huldt, Sofia
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Urban form, public life and social capital: a case study of how the concepts are related in Calabria, Italy2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis isto investigate the urban structure of two Italian towns based upon physicalstructure and social function. The towns are Bova and Bova Marina in theancient Greek part of Calabria, Area Grecanica. This is done by answering theresearch questions about how the urban structures are and what preconditionsthere are for public life and in extension social capital. This is alsocompared to the discourse in research about Calabria as a region lacking behindas well as the Greek cultural heritage. The thesis was conducted during onesemester spent in the area and based upon qualitative research in form ofobservations of the towns, mapping, textual analysis and interviews. Theresults showed that the urban form of the two towns differ from each otherbecause of their history and their localisation. Bova is an ancient town in themountains that is separated through topography, and therefore conserved withmany old structures but few inhabitants, suffering from out-migration. BovaMarina is placed on the coast of the Ionic Sea, south of Bova and connected tothe region by train and roads, while Bova is mainly connected to Bova Marina.Bova Marina was founded as a town in late 19th century and expanded a lotbecause of the railroad. It is a town with inconsistent walking network, a lotof traffic and houses in bad condition. Due to this the conclusion was that theurban form in both towns are seemingly bad for public life, but theobservations showed that there was intense social activity in public spacesnevertheless which generates social capital. Despite this the social capital isin research presented as bad in the Area Grecanica, something that might haveto do with a history of being neglected as well as lack of control over theirown area

  • Nilsson, Caroline
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Social hållbarhet ur ett kommunalt samhällsplaneringsperspektiv: En studie om Gävle kommuns definition av, åtgärder kring och arbetssätt för social hållbarhet2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Social sustainability is high on the agenda both internationally and nationally, but even though the work has been going on for over 30 years, Sweden has long to go before becoming equal. There are currently gaps in the Swedish research of social sustainability within urban planning. The purpose of this study is to investigate the possibility of strengthening the work of integrating social sustainability aspects into municipal urban and spatial planning in Sweden. In order to examine what the work on social sustainability looks like in Sweden, the study is applied to Gävle municipality. The study was conducted through a literature study and an interview study. The literature study shows that although there is no unanimous definition of social sustainability, several authors have tried to define the concept. A summary is that social sustainability can be divided into: Justice, Social Capacity, Holistic View, Collaboration and Participation, Access and Accessibility, Mixing and Variation, Affinity and Identity, as well as Well-being and Safety. The results of the interview study show that Gävle municipality has no unified definition of social sustainability and that they do not have an established working method to improve social sustainability although the interviewees identify several measures they use.

  • Egeskog, Johan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Cykelbanors bredd och cyklisters beteende: En metod för att uppskatta cyklisters upplevda risknivåer på olika bredder av cykelbanor2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this study was to investigate different standards of bidirectional bike lanes and investigate if they provide enough space for the needs of cyclists. A method was developed for evaluating cyclists’ behaviour using the theory of risk homeostasis and two risk-factors; speed and sideways position. An experimental design was also constructed and the results from the subsequent experiment implies that the two chosen risk markers could be useful in future studies relating to the design of bicycle infrastructure. A significant difference in the positioning of cyclists was found on different bike lane widths. The risk markers for sideways position show significant results at bidirectional bike lane widths below 2.4 meters. At such widths, cyclists seem to actively position themselves closer to the curb in the presence of oncoming cyclists. This is interpreted as a risk compensation which indicates that cyclists are not completely comfortable on that standard of bike lane. A conclusion would be to view bidirectional bike lanes at 2.4 meters width on flat surfaces, with adequate safety-zones beside the bike lanes, as a good standard for regular cyclists in many situations. More widening is not believed to provide major additional experienced safety or passability until the width allow for safe overtaking in the presence of oncoming cyclists.

  • Höglund, Jonathan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Dagsljus i stadsplaneringen: En fallstudie i Norra Djurgårdsstaden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Daylight has, since the mid 1900’s, been controlled in Swedish construction when Sweden achieved prosperity in society. Since then, the issue in how you plan for the best daylight conditions has had a number of major changes for it to become today’s functional requirement, controlled by Boverket and its building regulations BBR. The requirement has although been questioned lately as the building process has become much more complex which has renewed an interest of the issue during the 2000’s. That humans need daylight to feel good and to stay healthy is commonly known while it also can enable great savings in the energy use. The purpose of this study is therefore to study if the daylight issue is an important urban planning aspect and how good daylight conditions could be achieved when planning new residential areas. The goal is to evaluate the daylight conditions in Norra Djurgårdsstaden (Stockholm Royal Seaport), Stockholm’s environmentally-friendly urban development project, and its segments Västra, Norra 1 and 2. The goal is also to study how the issue was dealt with during the planning and building process. As a result, I hope that the study will generate interest and knowledge in how the daylight issue may be handled in the early stages of urban planning. The study is designed as a case study in order to, in an explorative way, investigate and briefly evaluate the daylight conditions of Norra Djurgårdsstaden. The study has embraced the method Vertical Sky Component, VSC, in order to provide a first indicator about the daylight conditions and to, in the early stages of urban planning, show upon possible improvements. As complementary work, studies of planning documents and interviews was made in order to investigate if and how the daylight issue was dealt with during the planning and building process. The results showed that the studied segments of Norra Djurgårdsstaden achieves relatively good daylight conditions and the problem lies within the limited daylight access where the segment Västra has the worst conditions. However, the current daylight conditions on the facades was improved in a later stage during the building process to reach the national requirement. The VSC-study alone can’t therefore investigate the actual daylight conditions in houses. The municipality has rarely brought up daylight as an issue in current planning documents but more frequently in later ones. This is also the trend in how the issue has been prioritized over time. The reasons behind this proved to be current urban planning trends and tough energy requirements along with new environmental certifications for buildings. Knowledge is also a key factor for the increasing interest in the daylighting issues, mostly brought up by builders. No discussions about the issues has occurred for the segment Västra in the early stages of urban planning as it is controlled in the latter permit process. This study shows that this is problematic and the issue needs to be discussed earlier in order to create better conditions to fulfil the national requirements. Yet again, knowledge and also awareness of the daylight issue is important. Today’s requirement set by Boverket has proven to be complicated to relate to during the urban planning and building process. Therefore, a development with clearer demands, directives, better interpretations and to some extent new calculation methods is needed. VSC could here be lifted as a possible method in order to easily and comprehensively analyse daylight conditions in early planning stages. The results from this studies’ VSC calculations highlighted some lack of sufficient daylight conditions and that it is possible to improve it and maintain the same degree of exploitation depending on how you plan.

  • Disputas: 2019-03-22 10:00 Science for Life Laboratory, room Air & Fire, Solna
    Svedberg, Gustav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi.
    Novel planar and particle-based microarrays for point-of-care diagnostics2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Point-of-care assays are easy-to-use, portable and inexpensive tests that can

    be used to aid diagnostics by measuring levels of disease-specific molecules

    in settings where access to advanced laboratory equipment and trained

    personnel are limited, such as at the patient's bedside or in low resource

    parts of developing countries. In order to achieve high multiplexing

    capacities, such assays can be based on planar microarrays consisting of

    spots immobilized on a flat surface or on particle-based microarrays based

    on populations of encoded particles. The aim of the work presented in this

    thesis is to develop new point-of-care amenable planar and particle-based

    microarrays that allow for highly multiplexed assays while maintaining low

    sample-to-result times, complexity and instrumentation requirements.

    Paper I demonstrates the use graphically encoded particles for colorimetric

    detection of autoantibodies using a consumer-grade flatbed scanner. Four

    graphical characters on the surface of each particle allows for millions of

    codes and the use of gold nanoparticles as a detection label allows both the

    code and the signal intensity to be read out in a single image.

    Paper II describes a signal enhancement method that increases the

    sensitivity of gold nanoparticle detection on planar microarrays. Using this

    method, detection of allergen-specific IgE can be carried out using a

    consumer-grade flatbed scanner instead of a more expensive fluorescence

    scanner without sacrificing assay performance.

    Paper III demonstrates the use of an isothermal DNA amplification method

    for detection of adenoviral DNA on a paper-based microarray. Using an

    isothermal amplification method eliminates the need for a thermocycler,

    reducing the instrumentation required for such detection.

    Paper IV shows the use of solid-phase PCR to amplify bacterial DNA directly

    on the surface of particles. This strategy reduces assay time by eliminating

    the need for separate amplification and hybridisation steps.

  • Disputas: 2019-03-15 11:00 Salón de Grados, San Sebastián, Spain
    Blanco, Blas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Development of new techniques for the numerical modelling of railway track dynamics. Application to rolling noise assessment2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The numerical modelling is widely employed for the prediction of the railway track dynamic behaviour, which is of utmost importance for the characterisation of the undesired medium-high frequency phenomena, such as corrugation, wheel-out-of-roundness and noise emission. This study is devoted to the improvement of railway track numerical modelling, the efficient resolution of the problem in the time domain and the assessment of rolling noise for different approaches of the track modelling.

    Regarding the enhancement of the railway track numerical modelling, two main core ideas have led the development of this task. On the one hand, the rail modelling, and on the other hand, the characterisation of the finite length nature of track supports. The proposals of this work include two basic premises, accuracy and computational efficiency.

    Firstly, the study makes use of Timoshenko beam theory for the numerical description of the rail. However, the conventional Timoshenko finite element involves drawbacks for the description of the rail dynamic behaviour and the calculation of the wheel-rail interaction in the time domain. These problems are addressed by improving the finite element formulation, which is based on the description of its local displacements.

    Secondly, the versatility of numerical methods is exploited to develop a distributed model of support. It substitutes the usual concentrated model, which entails overestimation of the periodicity effects and disruption of the wheel-rail interaction in the time domain.

    Thirdly, the advantages of the formulation of numerical models in the frequency domain are explored focusing on the ability to fairly describe the sleeper dynamics, the enhancement of the model boundaries and the realistic modelling of the track components dissipative behaviour. Moreover, the frequency domain response can be used to obtain the wheel-rail interaction in the time domain efficiently, by means of the moving Green's function.

    Lastly, this work deals with the assessment of rolling noise, in which particular emphasis is made on the influence of track dynamics in the noise prediction. At this regard, a methodology is proposed to account for the track periodicity, load speed and finite length of supports.

  • Kulkarni, Rohan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Design of Reliable Lightweight Cast Components: An Optimization Driven Design Appraoch2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The present-day automotive industry is striving to design lightweight components by optimizing the design for minimization of weight. The topology optimization is used widely for the design of lightweight components. The casting process is time and cost effective for mass production and widely adopted within the automotive industry. Generally, castability is not considered in the weight optimization process. These weight optimized components are optimized once again in the later stage for cost-effectiveness in the casting process. The modified design usually weighs more than the weight optimized design. The design can be optimized for weight and castability simultaneously in the early stage of design and this thesis report presents an optimization process for the same.

    The optimization process presents effective usage of the topology optimization to design lightweight components without compromising castability. It is a three-step process where thetopology optimization is integrated with solidification simulation along with DFX -castability evaluation. The reliability of the conceptual design is predicted based on the mapping of solidification and stress hotspots. The process is implemented to design three components of Scaniatruck and weight is reduced by 15% to 25%.

  • Shetty, Suhas Gururaj
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Failure Modeling of Curved Composite Beams: Numerical Modeling of Failure Onset and Propagation in L-Profile Beams2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The high strength/stiffness-to-weight ratio that composite materials exhibit has led to the utilization of composites as alternative to traditional materials in weight-critical applications. However, the highly anisotropic nature of composites renders the strength prediction under complex loading challenging. To efficiently predict the failure of composite structures especially in cases where out-of-plane stresses are dominant, the modeling of damage onset and propagation plays an essential role in accurate strength predictions.Firstly, in this Thesis work the analysis of a composite L-profile, which is loaded such that significant out-of-plane stresses are generated in the curved region, is conducted. However, the inherent heterogeneity at the micro/meso scale is not modeled for the stress analysis.Secondly, in this project the target was to accurately predict the initiation of failure at the ply level, modal based Puck’s matrix failure criteria have been implemented to the failure analysis. Maximum stress failure criteria were however retained to check the possible fiber-based failure which is not directly captured with in Puck’s failure criterion.Thirdly, Cohesive Zone Material Model has also been employed to model the growth of interlaminar damage (delamination). The delamination study is based on the Inter Fibre Fracture crack initiation and doesn’t include other causes like edge effects, voids, manufacturing defects etc.Finally, the attempt to validate the analysis results with the available test results was made. Further development of the existing model and several tests are required to be carried out for material characterization and complete validation of the developed damage model for composite structure.

  • NADELLA, Venkata Raghurama Swaroop
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    CFD Simulation of MQL with low temperature and high-pressure coolant2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Att använda stora mängder skärvätskor vid en bearbetningsprocess har potentiellt negativ inverkan inte bara för operatören men också på miljön. Utöver detta tillkommer ökade kostnader för tillverkningsprocessen. För att minska skärvätskekonsumtionen under maskinbearbetning införs en teknik som kallas minimalsmörjning(MQL=Minimum Quantity Lubrication) som använder mycket mindre mängd skärvätska men ändå är effektivare än standard kylspolning med skärvätska.

    Denna avhandling fokuserar på att bestämma konvektionen över ett skär med en konstant värmekälla placerad inuti ett kvadratiskt hölje och beräkningsdomänen för den CFD-modell som presenteras, vilken består av flytande och fasta domäner och interaktion mellan dessa. Möjligheten att använda MQL då lågtemperatur- och högtryckskylmedel appliceras undersöks och hur temperaturen sjunker efter applicering av kylmedel/kylvätskor observeras genom att simulera förhållandena i ANSYS flytande arbetsbänk. Denna tekniks effektivitet bestäms med avseende på huruvida högtrycks- och lågtemperaturkylvätska kan avleda värme och transportera bort spånor från ingreppszonen. Slutligen sammanställs resultaten och därpå dragna slutsatserna.

  • Yousif, Robert
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    A Practical Approach of an Internet of Robotic Things Platform2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis aims to design and develop a platform based on a novel concept - the Internet of Robotic Things (IoRT) constructed by a robotic platform, an Internet of Things (IoT) platform and cloud computing services. A robotic platform enables hardware abstraction, facilitating the management of input/output between software, mechanical devices  andelectronic systems. The IoT platform is a global network enabling a massive number of devices known as things to communicate with each other and transfer data over the Internet. Cloud computing is a shared pool of scalable hardware usually provisioned as cloud services by third party cloud vendors. The integration of these concepts constitutes the core of the IoRT platform, as a global infrastructure facilitating robots to interconnect over the Internet utilizing common communication technology. Moreover, the pool of cloud resources shared by the connected robots enables scalable storage and processing power.

    The IoRT platform developed in this study constitutes firstly of the Amazon Web Service (AWS) IoT core serving as the IoT platform. Secondly, it incorporates the Robot Operating system (ROS) as the robotic platform and thirdly the cloud services Amazon DynamoDB and AWS Lambda for data storing and data processing respectively.The platform was evaluated in terms of delays & utilization and visualization capabilities. The platform demonstrates promising result in terms of delays exchanging small packages of data, round-trip delays in order of 50-60ms were obtained between a robot placed in Stockholm and the communication platform AWS IoT placed in Dublin, Ireland. Most of the delay is due to the traveling distance, where a round trip ping between Stockholm and Dublin takes around 50ms. The platforms ability to visualize streaming data from the robots, enables an operator to visualize selected data from any service in the platform over the Internet in near real-time, with round-trip delays in order of 250-300ms where the data propagates through multiple cloud service. In conclusion, this report illustrates the feasibility of merging two major platforms together: ROS and AWS IoT, and moreover, the accessibility to exploit the power and potential enabled by the modern data centers.

  • Igual Escriche, Miguel
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Assessing the feasibility of implementing DC-microgrids in addition to USB-C and rooftop PV in households and offices: The Cases of Sweden and Spain2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Thesis’s frame is the feasibility of DC-microgrids at buildings environment. Nowadays, there is plenty of literature available regarding the benefits of implementing DC at buildings instead of AC as a means of optimizing photovoltaic generation PV on the grounds of minimizing conversion losses, with an overall energy saving of about 5-12% [1] [2]. Studies conclude that even more energy, up to 14%, could be saved if Local Energy Storage (LES) was also integrated in the equation [1]. Basing its findings on this data and on the many papers and publications that ratify these conclusions, this Thesis aims to provide a new contribution on this issue.

    Thanks to the baseline discussion, where all the relevant information, inputs and facts that support the hypothesis of the Thesis had been presented, the model was developed in order to assess the feasibility of implementing DC-microgrids in addition to USB-C and rooftop PV in households and offices for both countries, Sweden and Spain. Each country represents different weather condition settings but also different sociopolitical commitments to both the environment and the renewable energy generation movements, and the model this Thesis has developed, has been capable to take all of this into account and provide coherent conclusions.

    Different scenarios, dependent on the DC market penetration, have been carried out through the model thanks to Microsoft Office Excel. The aim of the model per se was to provide answers about the energy, environmental and economic consequences that developing a hybrid grid with both AC and DC power infrastructure have on buildings equipped with rooftop PV. Furthermore, the profitability of creating “free storage” through USB-C have been studied in two different typologies of buildings, one with the PV generation matching the consumption in time, the offices, and other without this coincidence, the households, where the demand significantly varies after the sun goes down.

    After optimizing the number of PV modules and the amount of electric storage for each typology of building and country, the results of the Thesis show how non-technical aspects have strong positive or negative economic consequences in both countries but, nevertheless, the implementation of the system proposed carry considerable environmental savings independently on the DC penetration. Finally, office buildings have stated themselves as the most interesting typology of building to implement the system analysed. 

  • Dhital, Avinash
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Opportunities for small-scale anaerobic digesters for hotels and restaurants in Kathmandu, Nepal2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    About 83% of total energy consumed in Nepal comes directly from the solid fuels. The import of Liquified Petroleum Gas (LPG) is also growing at an exponential rate. The hospitality subsector (hotels and restaurants), one of the key economic subsectors in the country, consumes most of the energy within the commercial sector primarily for cooking purposes. The bio-waste generated from growing hospitality subsector and other sectors in Kathmandu is poorly managed. Similarly, on the other hand, Nepal has an extensive knowledge and experience of manure based anaerobic household biogas systems mainly in rural areas. Based upon this situation, the thesis investigates the opportunities for anaerobic biogas production for cooking at hotels and restaurants by utilizing their own organic waste. Currently available biogas technologies, important parameters affecting the biogas yield, policy and financial supports and case studies of various stakeholders employing the biogas technologies in the hotels and restaurants in Nepal were considered. The most applicable technology for the purpose was then chosen. The organic waste sampling study from randomly selected 4-star hotel (Yatri Spa and Suites), tourist standard hotel (Hotel Bliss International) and restaurant (Fren’s Kitchen) in Thamel, the tourist zone of Kathmandu was conducted. Similarly, various data especially focusing on the current cooking energy need, demand, supply, cost, organic waste management of the hotels and the restaurant was collected through questionnaires and series of interviews. The average amount of daily organic waste and organic waste fraction for Yatri, Bliss and Fren’s was found to be 61.3 kg and 63.0%, 18.4 kg and 82.7%, and 16.3 kg and 81.8% respectively. Similarly, the variations in weekly organic wastes and waste generated per guest was also determined. Based upon the amount and characteristics of organic waste from the sampling survey, the theoretical biogas potential of the organic waste at digester output rate of 0.27 kWh/kg/day for JUAS digesters, the technology selected for the biogas conversion, was found to be 18.4 kWh/day, 5.5 kWh/day and 4.9 kWh/day equivalent to 4.9%, 3.0% and 5.4 % of the current daily energy need for Yatri, Bliss and Fren’s respectively. Similarly, the economic implications of the small-scale biogas technology if employed in the hotels and the restaurant was scoped out. It was found that the recommended Polyvinyl Chloride (PVC) based 3000 l sized JUAS bio-digesters had positive Net Present Value (NPV), Internal Rate of Return (IRR) and payback time of around 5 years on average for all the eateries under study. The monthly life cycle cost of the integrated LPG-JUAS system is found be cheaper for all eateries as compared to the current LPG system. Levelized Cost of Energy (LCoE) of the JUAS digesters is calculated to be competitive as compared to energy from other renewables in the country. There is, however, need to improve the digester conditions to get higher biogas yields. For the wider adoption of the digesters across urban sectors, the subsidies amount should also be increased together with information dissemination regarding biogas uses and its potential among the stakeholders.

  • Caulcrick, Oluwatofunmi Oluwatobi
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    The Electricity Model for China – Insights and Implications of Energy Policies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    China remains one of the largest producer and consumer of energy in the world. An understanding of the complex nature of the energy resources in this country is of a high interest due its impacts on global scale. In this Thesis, the electricity supply system of China is modelled using the medium to long-term open source energy modelling system tool OSeMOSYS. Three scenarios are developed and analysed. A Reference scenario that incorporates into the model the country´s current energy policies and targets. A Renewable energy scenario that represents the reaction of the energy system based on an ambitious penetration of renewable energy technologies as well as a Climate change scenario. The latter one, provides an assessment of the electricity sector based on the emission limit set to achieve under the Paris Agreement "below 2 degrees climate goals". Finally, comparison is made between all three scenarios and results show that the energy policies and the current ambitious penetration of renewable energy technologies are not sufficient in meeting the climate change goals in the short term.

  • Gabaldon Moreno, Andrea
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Förnybar energi-driven membrandestillering för rening av dricksvatten: Main Ethiopian Rift Valley fallstudie2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fluoride is present in all type of water sources, but levels beyond the current World Health Organization guideline of 1.5 mg/L can be very harmful for people’s health. Due to the volcanic nature of rocks in the Ethiopian Rift Valley, groundwater is contaminated with fluoride, and studies have even recorded levels up to 26 mg/L. These excessive levels are affecting more than 14 million women and children in Ethiopia. Providing population with safe and clean water could help to achieve the Sustainable Development Goal 6 (i.e. Ensure availability and sustainable management of water and sanitation for all) from the United Nations. Membrane distillation systems have been extensively tested in literature, proving to be effective in removing fluoride, even at higher concentration levels (500 mg/L). Membrane distillation is a heat driven system that works under feed water temperatures below 100 ºC. Renewable energy sources such as geothermal, solar or biomass can be used to provide that heat. This report evaluates techno-economically different technologies using TRNSYS: flat plate solar collectors, evacuated tube solar collectors and biogas from animal dung, as heat source for the membrane distillation unit. The size of the hypothetical installations was optimized to cover the demand of 30 households. Several indicators were calculated to compare the different technologies: specific energy demand, water production, and efficiency of the systems. Investment costs and operation and management costs were considered to calculate total costs and payback period of the different installations. The results show that the best techno-economic option to be installed is a hybrid model that includes a combined heat and power unit powered by biogas and evacuated tube collectors, as can meet the demand with one membrane distillation unit and also supplies electricity and biogas for cooking. However, depending on the specific location, the availability of solar radiation and manure can vary, and consequently the best option will change. In case the existence of livestock is limited, three membrane distillation units coupled with 85 m2 of evacuated tube collectors can cover the demand. If the availability of sun is limited one membrane unit coupled with a standalone biogas unit can be considered. Flat plate collectors are never the best option, as they require the biggest investment cost. Nevertheless, the existence of local manufacturers can decrease the costs. 

  • Andersson, Martin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Comparison of solar thermal and photovoltaic assisted heat pumps for multi-family houses in Sweden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The building sector account for 40 % of the global energy demand, and an increasingly popular way to supply buildings with heat is through the use of heat pumps. Solar thermal (ST) can either be used as a low temperature energy source in the heat pump or to directly supply the building’s heating demand. 

    The increasing market of PV has made it a favorite for roof-top solar installation. Its physical integration with buildings and HPs is simpler than that of ST and can supply any available electric load associated with the building and not just the HP system. It can also supply any excess power to the grid. 

    In order to properly compare these two options, key performance indicators (KPIs) were identified for several system boundaries within the building and HP system. Technical KPIs used were seasonal performance factor (SPF), solar fraction (SF) and self-consumption (SC), while internal rate of return (IRR), net present value (NPV), profitability index (PI) and payback time was used to evaluate their economic performance. 

    For the thesis a multi-family house was modelled in TRNSYS where different system sizes of either ST or PVs was simulated for a year with three-minute intervals. The ST was connected in a parallel configuration thereby supplying the building’s domestic hot water (DHW) through a separate storage tank. The modelled heat pump was a ground source heat pump (GSHP) which utilizes boreholes as the low temperature energy source.

    The SPF increased for both the ST and PV integration from the reference scenario (no PV/ST integration) but to a varying degree depending on the analyzed system boundary. The economic results suggested that PVs are the more financially sound option over ST for the simulated MFH. The sensitivity analysis also showed the large impact of economic assumptions on the expected profitability for both the PV and ST systems. Based on the results would the simulated MFH with an existing GSHP benefit more from installing PV instead of ST from both a technical, economic and environmental perspective. 

    It is reasonable that PVs will most likely be an integral part for future buildings in Sweden with or without HPs because of its financial strength and versatility of demand supply, especially compared to ST.

  • Disputas: 2019-03-14 10:15 F3, Stockholm
    Karlsson Hagnell, Mathilda
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Technical cost modelling and efficient design of lightweight composites in structural applications2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A lightweight transport design reduces fuel costs and emissions and can be achieved through the use of fibre-reinforced composite materials. Although lightweight, the composite raw material can be expensive and the sequential component production challenging and costly. To design weight- and cost-efficient composite structures and find ways to reduce production costs, technical cost modelling must be applied. In this thesis, a technical cost model for composite manufacture, assembly and basic inspection is proposed and implemented to identify cost drivers, evaluate trending design strategies and suggest appropriate composite design guidelines for transport and aeronautical applications. 

    Among identified cost drivers, material costs dominates at 50-90 % of the total part cost also for low annual volumes. Tooling costs are second in importance for slow processes and large parts while the importance of investment and labour depends on degree of automation. Part integration is shown to only marginally reduce cost. Traditional composite assembly is in turn found to potentially reduce costs by 30 % through the elimination of non-value-adding processes such as shimming and part positioning. In comparison to part integration, sandwich design exhibits superior cost- and weight-efficiency for low-to-intermediate stiffness levels. Moreover, the industry impact of a sustainable, circular recycling flow of composite materials is estimated and shown to give up to halved raw material costs as well as cost returns also for virgin carbon fibre users. Low-cost fibres such as glass, lignin-based carbon, hemp and recycled carbon fibres are found to be highly cost-competitive also for structural adaptions.

    The technical cost model, method and results presented in this thesis provide important composite design conclusions and a foundation for further modelling work needed to reach that elusive weight- and cost-optimal composite design.

  • Wikström, Rebecca
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Real-time Traffic Sign Detection and Classification: Evaluation of Image Processing performed on an FPGA-based platform2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As a part of the development of autonomous vehicles and advanced driver-assistance systems (ADAS), vision systems are used as a method for collection of extensive data about the surrounding world [1]. This data can thereafter be processed and information can be extracted. Due to the safety-critical nature of automotive applications, the image processing of the camera stream must be performed in real-time [2].

    This thesis investigates how a system with real-time performance potential - an FPGA-based system - can be utilised to perform image processing applications. Specifically the thesis looks into the research area of traffic sign detection and classification. A literature study is presented, along with a proposed implementation of a Traffic Sign Detection and Classification (TSDC) system.

    The conclusion of the literature study is that many different methods have been tested previously but their performances are hard to compare. One of the most common approaches for FPGA-based implementations was chosen, due to its simplicity yet proven high accuracy by previous FPGA-based implementations. The approach - a colour thresholding and template matching - was partly implemented using the manufacturer Xilinx’s developing tool Vivado and High Level Synthesis (HLS).

    The entire system was never implemented due to lack of time. However, the colour thresholding part of the algorithm was implemented and provided good result with a throughput of 209 frames/s, very low hardware utilisation and a low power consumption of 0.016 J/frame. This was determined using Vivado’s Design Evalu-ation tools.

    A proof of concept was provided for the classification part of the system, that was never implemented on the platform, which showed that the classification part would likely constitute a performance bottleneck to the system.

    The detection and classification results proved that if there was a sign in the image it was found 96.0 % of all cases on previously unseen data, but of those where only 79.0 % classified as true positives. In addition to this 34.9 % of the previously unseen images not containing the searched-for sign, were a false positive.

    The conclusion of the thesis is that for a full system to be implemented, more of the tasks need to be performed on the FPGA, in order to have the potential to perform in real-time. One proposal to achieve this, is to implement a region of interest extraction, so only a single scale template match could be performed.

    However, given the classification results, it is probably a too simple classifier for the problem. Another conclu-sion is therefore that a more sophisticated classifier would be of interest to test instead.

  • Hatemipur, Hussein
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Embedded programming and construction of the PCB SiC In Space Experiment2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis consists of the compilation of four previous bachelor theses as well as the continued work that has been carried out within the SiC in Space project, which is a part of the student satellite project MIST in KTH.

    SiC in Space is a project whose aim is to examine and verify the characteristics of the semiconductor Silicon Carbide, SiC, in harsh environments, in space specifically. In order to carry out the tests on SiC, a PCB was designed, where the BJT measurement circuits, voltage circuits, selection of MCU as well as software, assembling and testing of the final PCB, were divided in four parts, due to the size of the project.

    This work discusses testing, programming and verifying of the previous designed PCB:s as well as the design of a new PCB which includes new requirements and specifications from MIST.

    A test oriented approach of programming was made to verify that the circuits met the desired functions in order to put together a complete programme for automatic measuring and communication with the satellite.

    The errors that were discovered in carried out tests, were adjusted for the new PCB, making it in accordance with all the requirements set by the MIST- and SiC group.

  • Swaminathan, Pramod
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Utveckling av gasutbytesmodellering och reglerstrategi för spark ignited engine2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Regeringens lagstiftare ökar ständigt kraven på att kontrollera utsläppen från tunga fordon för att upprätthålla hållbar miljö. Samtidigt ökar också behovet av snabb respons och lägsta bränsleförbrukning ur kundens perspektiv. För att möta efterfrågan måste den integrerade kontrollarkitekturen göras robust och snabb genom att använda optimalt luftmassflöde och EGR i cylindern för att få önskat vridmoment genom att upprätthålla luftbränsleförhållandet (AFR) som stökiometri i alla driftsområden. För att upprätthålla temperaturen och trycket i avgassamlaren har EGR (exhaust gas recirculation) införts i de gnisttändda motorerna, vilket förbränner de återcirkulerade avgaserna. I denna uppsats har en modellbaserad styralgoritm utvecklats genom modellering av trottel, EGR och waste-gate ventil med korsfrekvenser. Algoritmen syftar till att uppnå det önskade luftflödet och EGR så fort som möjligt under transienter vid alla driftspunkter (motorvarvtal och last). För att utvärdera kontrollstrategin modellerades en femcylindrig motor i programmet GT-SUITE. De modellbaserade regulatoralgoritmerna är utvecklade i SIMULINK genom att upprätta en kommunikationslänk med funktionell Mock-Up Interface (FMI). Den modellbaserade reglering är framkopplad med en förstyrning i form av en "Gain Schedulerad" PID regulator vilken är integrerad med modellen till en kaskadreglering. En serie av transienta steg har analyserats genom att steg i last gjordes vid olika motorvarvtal. Den algoritm som utvecklas gav tillfredsställande resultat där svarstiden har ökats och oscillationerna dämpas i större utsträckning.

  • Ingvarsson, Gustaf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Assessment of a Thermal De-Icing Solution and Control Methods using Simulations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Lastbilar körandes i nordiska vinterförhållanden riskerar att strålkastare, och andra lyktor blir täckta utav is. Detta hindrar ljuset från att skina på vägen, något som måste åtgärdas manuellt utav föraren. Tidigare har problemet varit löst genom den extra värme som strålas från glödlamporna i lyktorna men i och med övergången till LED har detta problem vuxit. Strålkastarna är nu i behov av en lösning som kan ta bort, samt förhindra att ny, snö och is från linserna.

    Detta examensarbete, som utfördes på Scania CV, Södertälje, undersöker kontrollmetoder för en termisk avisnings lösning. Projektets huvuduppgift har varit att utveckla och använda en simuleringsmodell för avisnings processen. Modellen används sedan för att jämföra två stycken kontrollmetoder för avisningen och för att förhindra att ny is bildas.

    För att hitta en lämplig termisk avisningslösning undersöktes de tre alternativen för värmetransport i material. En potentiell lösning för varje alternativ jämfördes sedan med varandra. Den bästa lösning var den som använder värmeledning i form utav värmeslingor i linsen. Denna lösning låter värmaren vara nära isen och använder sig av den effektivaste transportalternativet. Värmaren inkluderas i simuleringsmodellen om beskriver värmetransporten i en lins täckt med is.

    Två kontrollmetoder valdes sedan baserat på en litteraturstudie inom området. Studien resulterade i två hybrid controllers, en som använder sig utav gain-scheduling och en andra som använder sig utav en smith-prediktor. Både metoder implementerades i simuleringsmodellen och deras prestanda jämfördes. Hybrid controllern med smith-prediktorn fanns vara den metod som presterade bäst, då den var både snabbare samt hade mindre översläng. Metoden visade sig dock vara känsligare mot störningar på återkopplingen.

    Kontrollmetoden med smith prediktorn är den som rekommenderas för användning i vidare arbete med den avisnings lösning. Ett första steg innan implementering med hårdvara föreslås vara jobb på ett filter för återkopplingen.

  • Lions, Alexandre
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    IMPROVING THE REPRESENTATION OF 1D PERFORMANCE COMPRESSOR MODEL2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The thesis project was carried out at SAFRAN AIRCRAFT ENGINES in France with goal to check the feasibility of implementing 1D validated aerodynamic models into the engine performance models. It is a part of a wider project of improving the representation of transient and steady effects that are missing in 0D representations. The main difficulty is to implement this 1D model in the PROOSIS performance software. The focus of the project was to implement the subsonic to choke range of operating conditions consistently within the PROOSIS solver. Therefore, using only simplified aerodynamics, a first instance of the model was programmed. A second instance of the model was able to take into account the choking phenomena. The solution found works in the PROOSIS tool which is a non-causal programming software and manage to unite the subsonic to choke operating range in a single physical system. The model once enriched with the right correlations will be able to be used in a performance model, replacing the compressor maps.

  • Öström, Linn
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematisk statistik.
    Post-processingof Monte Carlo calculated dose distributions2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master Thesis focuses on denoising of Monte Carlo calculated dose distributions of radiosurgery treatment plans. The objective of this project is to implement a Denoising Autoencoder (DAE) and investigate its denoising performance when it has been trained on Monte Carlo calculated dose distributions generated with lower number of photon showers. The DAE is trained in a supervised setting to learn the mapping between corrupted observations and clean ones. The questions this thesis aims to answer are: (i) Can a DAE be used to denoise Monte Carlo calculated dose distributions, and thus predict the dose prior to a full simulation? Additionally, (ii) does incorporating prior knowledge of shot position increase the denoising performance? The results in this investigation have shown that the network successfully predicts the dose for low number of photon showers. In very heavy noise inputs the network denoising was in general successful, and the network could fill in missing data. The results indicated that the DAE could reduce the level of noise with an amount comparable with simulations that were done with 102 times more samples.

  • Leclercq, Benjamin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    A review of energy modelling tools2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master’s thesis is the outcome of a six-month internship at TOTAL in the Gas, Renewables, Power market analysis department. In a process to revise the long-term energy model used by the company which covers numerous countries and sectors, the objective was to develop the foundation of an energy demand model with a parallel focus to better represent the variations of power demand. 

    A literature review is first carried out on different approaches for energy demand models and on the load duration curve which enables to aggregate power demand variations. The outcome of this review is that it is common to use a top-down econometric strategy for the energy demand and that there are various methods to model the load duration curve.

    An econometric demand model is then developed using a simple econometric approach with demand elasticities to end-user prices and to activity variables that are representative of a sector’s socio-economic activity. With such an approach, the model can correctly draw a country’s energy demand using relatively small datasets and offering the possibility to create scenarios and sensitivities.

    In addition, two load duration curve models are further investigated, one model using typical periods of the year and a second one using a normal distribution law. The latter option appears to be the most convenient as it requires only an annual power demand and a standard deviation value to reasonably well represent the load curve.

    As a case study, the dynamic-systems modelling software VENSIM is introduced with its relevant features that can enhance the development of the code and analysis practices.

  • Abdo, Aslan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Modeling contingency infiltration scenarios in MODFLOW: Stockholm Bypass and tunnel induced groundwater drawdown2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Subsurface constructions, such as tunnels, create hydrogeological challenges in mitigating risk of subsidence due to groundwater drawdown. Presenting readily made precautionary mitigation plans, such as strategically planned artificial recharge applications, can help effectivise the mitigation process.

    The Bypass Stockholm project comprises of several subsurface constructions which may lower the surrounding groundwater level through tunnel leakage. Risk of land subsidence persists in the nearby urban area of Vinsta, Stockholm, where a groundwater drawdown may cause the clays in the area to experience land subsidence. A hydrogeological modelling approach was used in the area to create strategic artificial infiltration plans that could be employed as a mitigative response to the drop in groundwater head.

    In order to simulate the potential tunnel drainage, a steady state hydrogeological model was built using MODFLOW. A 220 l/s tunnel leakage was then simulated. Four different artificial groundwater infiltration scenarios were then conceptualized and simulated to observe effects on groundwater heads.

    The groundwater levels of the baseline model of the area fit the calibration targets with average absolute deviation of 0.18 m. The tunnel drainage scenario lowered the groundwater level in the till aquifer and bedrock by 0 - 1.5 m and 0.5 - 5 m respectively, with higher drawdowns observed closer to the tunnel. The infiltration scenarios mitigate the groundwater drawdown with different efficacies; proximity to the recharge point, and discharge into the till aquifer were observed to have the highest effect on groundwater recharge in the model. The model could have been improved by improving the data quality surrounding the hydraulic conductivity of the bedrock, as it had the highest effect according to the parameter sensitivity analysis.

  • de Almeida Cavaleiro de Ferreira, António Maria Mendes
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Circular Economy in Cities: Framework Development & Porto (Portugal) Case Study Analysis2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Circular Economy (CE) is a recent concept that is gaining strength worldwide due to China's implementation and the European Union (EU) contribution. It is seen as the alternative to a wasteful linear economic system, with the aim to keep products at higher value and for longer time. Together with it, there is a trend of urbanization, with already 50% of the population living in cities and with expectations of this share to rise to 70%.

    This work main goal is to understand the role of cities in CE implementation and its monitorization. To do so one started by understanding the key concepts and state-of-the-art behaviours and technologies associated to CE, alongside an understanding of its history. Furthermore, one shifted this definition to an urban context, understanding how a circular city should look like and how and where it could leverage circularity, by also benefiting from it.

    Finally, a framework for the city analysis was developed, together with a Case Study relating Porto, Portugal, analysing this city from a representative perspective, while taking conclusions from the respective results. The framework is based in CE key concepts, as transparency, modularity and flexibility. It allows the definition of relevant sectors in the city, its evaluation and the interaction between them, aiming for a holistic approach.

    Major conclusions were taken from this work. First, Porto was considered a city with potential to be circular. Moreover, it has the opportunity in leading, together with cities as Amsterdam, Barcelona and Glasgow, the urban transition towards CE.

    Second, the relevant indicators for CE are yet to be defined, with this responsibility laying between the EU and the Ellen MacArthur Foundation (EMF), and, besides evaluating circularity in different levels and sectors, shall also be realistic, concerning data that can be collected today, recommending meaningful data that shall be collected in the near future. Furthermore, a multi-criteria analysis can be later included, connecting the different indicators of each sector, and then the different sectors.

    Third, the developed framework is a multi-sectorial framework, based in a meso-macro level. Due to CE properties, a framework of multi-level is required. The flexibility of the framework allows the analysis of different cities, in its different sectors and behaviours. Its modularity allows the connection to similar frameworks, based on the one developed in this work, that shall reflect a macro-level (national, European and global), a meso-level (focusing on the sectors and companies) and a micro-level (product), giving the holistic analysis characteristic of CE.

  • Ericson, Peter
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Residual stresses in Ti-6Al-4V from low energy laser repair welding2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Millimeterstora och svårupptäckta defekter kan uppstå internt i stora och komplexa gjutgods av Ti-6Al-4V, ibland går dessa oupptäckta tills detaljen genomgått mekanisk bearbetning och en stor kostnad redan har gått in i den. Dessa defekter och andra industriella olyckshändelser leder till ett behov av additiva reparationsmetoder där den för tillfället rådande metoden är TIG-svetsning. Denna metod reparerar defekterna men leder till oacceptabla restspänningar vilka kan åtgärdas med värmebehandling som i sin tur kan orsaka ytdefekten alpha case. Därav finns ett industriellt behov av reparationsmetoder som leder till mindre eller negligerbara restspänningsnivåer i reparerad detalj.

    Detta arbete utfört hos GKN Aerospace – Engine Products Sweden i Trollhättan analyserar eventuella förhållanden mellan parametrarna Effekt, Spot size, och Svetshastighet och de resulterande restspänningarna i ett lågparameterområde på materialet Ti-6Al-4V.

    En parameterrymd uppspänd av 17 parameteruppsättningar etablerades, svetsades och analyserades med mikrografi. Ur denna rymd simulerades de 8 yttre parametrarna med hjälpa av Finita Elementmetoden i svetssimuleringsmjukvaran MARC och ett förhållande mellan ingående parametrar och resulterande restspänningar undersöktes.

    En statistiskt säkerställd trend erhölls för att en minskad Svetshastighet leder till minskade tvärspänningar i mitten på en 20mm lång svetssträng. Detta är applicerbart för svetsar nyttjande start och stopplåtar.

    Det noterades även att en ökning i Effekt eller Spot size, eller en minskning utav svetshastigheten leder till att det av restspänningar utsatta området ökar i storlek. Detta är har implikationer för efterföljande värmebehandling i avgörandet av form och storlek på området som skall värmebehandlas.

  • Enefalk, Tommy
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Improvements to Thermal Management System for Automotive Components2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Global warming imposes great challenges, and anthropogenic greenhouse gas emissions have to be reduced by active measures. The transportation sector is one of the key sectors where significant reductions are desired. Within a vehicle, the cooling/thermal management system is a subsystem intended for temperature control of automotive components. Reducing the power consumption for thermal management is one of several possible ways to reduce the environmental impact of the vehicle. This report considers an existing reference cooling system, with three separate circuits at different temperature levels. The purpose is to suggest improvements to the reference system with respect to increasing energy efficiency as well as reducing the number of components. Potential improvements are identified during a literature study, and then evaluated one by one. After the first evaluation, four improvements are selected: Firstly, a liquid-to-liquid heat exchanger in high temperature circuit, with connections to both the medium and low temperature circuits. Secondly, common medium/low temperature radiators, which can be allocated according to cooling demand. Thirdly, pipe connections for coolant transfer between the low and medium temperature circuits. Finally, a liquid-cooled condenser in the active cooling system, cooled by the medium temperature circuit. The result is a system with flexible radiator allocation, more even load distribution, ability to heat components using heat losses from other components, and one radiator less than the reference system. A complete system evaluation is performed in order to find the most beneficial arrangement of the components. Steady state calculations are performed in MATLAB, using five different operational cases as input data. Out of six different alternatives, one is recommended for high load operation and another for low load operation. The difference between the two is the position of the condenser, since a low condensation temperature should be prioritized at part load but not at high load. The main uncertainties of this report are steady state calculations, which are not fully reflecting real driving situations, and approximations due to lack of input data. For further work, verification of these results by transient simulations and practical testing is recommended. Removing one of the high temperature radiators could be investigated, as well as downsizing the medium temperature radiator. Integration with the cabin thermal management system, which is beyond the scope of this report, is also a relevant area for future investigation. By suggesting improvements to an automotive subsystem, this report strives to make a difference on a small-scale level, but also to contribute to an ongoing transition process on the global level.

  • DIZIER, Antoine
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Techno-economic analysis of floating PV solar power plants using active cooling technique: A case study for Taiwan2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The development of large scale solar photovoltaic (PV) power plant is of great interest, especially in regions with favourable weather climate conditions such as Taiwan. However, designing large scale systems brings several challenges, including land availability as well as dealing with high temperature impact on PV modules. Combining floating PV plant (FPV) and active cooling system is a promising collaboration, using water availability on site to cool down the PV panels on a regular basis. FPV plant can be installed on unused water bodies to save land for other activities. Spraying water on the PV modules can help increase daily production and reduce system losses. The utilization management of such cooling system needs to be planned and optimized, according to local meteorological conditions. Therefore, this thesis study aims to investigate the impacts of implementing an active water cooling system on the FPV plant techno-economic performance. The objective is to design different cooling utilization strategies and analyse the behaviour of the FPV plant, evaluating whether or not the combined FPV and cooling system is technically efficient and economically viable. In this thesis work, a techno-economic analysis is performed based on FPV plant and water cooling models, given specific weather climate and economic conditions at the chosen location. The developed models are implemented with MATLAB and simulations are carried out on real data collected from a planned FPV plant at Sugu site in Taiwan. Performance indicators are then calculated and compared for different cooling strategies. For the given technical and economic assumptions, introducing PV panels cooling at an optimal maximum irradiation value shows a net yearly generation gain of 6.6% in comparison the FPV alone. This configuration increases capital costs but provides a 9.1% reduction in the solar plant payback, while slightly reducing the cost of electricity.

  • Attanayaka, T.L.B.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Open Source Energy Model for the Electricity Sector of Sri Lanka2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A long term generation expansion model for the electricity sector of Sri Lanka was developed in this thesis. The model provides the least cost development pathways to cater the future electricity demand within the user defined constraints that need to be adhered. Starting from the present electricity system of the south Asian island nation, the model spans for the period from 2018 to 2050.

    Open Source Energy Modelling System (OSeMOSYS) was used to create the model. It utilises linear optimization and minimize the net present value of the modelled system in the entire period. Four electricity end user sectors were modelled namely, residential, industry, services and transport. Final electricity demand at present is around 13 TWh and it is projected to grow at a rate of 5.6% per annum for the next ten years to be around 24 TWh in year 2028 and to rise at a rate of 4.3% per annum there onwards to exceed 61 TWh in year 2050. Twelve fuel options were used by the existing and candidate technologies for electricity generation in the model, namely biomass, coal, diesel, furnace oil, hydro, liquefied natural gas, naphtha, natural gas, nuclear, residual oil, solar and wind. Electricity production in different levels such as transmission, distribution and end user locations were modelled in the system. Capital cost, fixed and variable operation and maintenance cost and salvage value of technologies were considered for the cost optimisation. Environmental emissions were included in the model and CO

    2 emission limit of 20% for the modelling period was included in the Base Scenario to represent the expected development pathway of the country in the future. Scenario analysis was conducted to examine the sensitivity of input variables such as electricity demand and hydro condition, and the impact of user defined constraints to the least cost solution. Renewable energy integration in to the system was studied and the impact of higher shares of renewable energy was examined. Capacity mix, energy mix, CO2 emission and LCOE of different scenarios were compared in the analysis.

    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    UAVs for railway infrastructure operations and maintenance activities2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The railway infrastructure needs to be safe, reliable and efficient in order to meet the growing demand of sustainable transportation methods. One of the main problems the railway industry faces today is that a higher traffic load increases the need for maintenance, at the same time as it reduces the availability of gaps in the timetables to perform maintenance activities. Unmanned Aerial Vehicles, UAVs, have in recent years been adopted commercially due to their potential of increasing work efficiency and productivity. Different actors in the railway industry have recently started to explore and test the possibilities of implementing UAVs. The objective of this master thesis was to investigate and define use case scenarios where the use of UAVs would create value for railway infrastructure operations and maintenance activities. It is meant for both stakeholders in the railway industry to gain better understanding of capabilities and limitations of UAV technology but also provide recommendations to UAV manufacturers to understand the railway industry and potential UAV applications. Theoretical research and qualitative user studies with UAV professionals and relevant stakeholders within the railway industry were conducted in order to gain insight in the railway industry and to identify potential use case scenarios. The research showed that maintenance activities to a large extent are performed either manually by walking along the tracks which is inefficient, physically demanding and dangerous or by using test/measurement vehicles which require track occupancy. It was concluded that the use of UAVs would mainly create value by; enabling remote inspection and operation, accessing the infrastructure without track occupancy or the need of roads. At the same time, improve the working conditions, efficiency and quality of maintenance activities. The thesis resulted in 15 potential use case scenarios for UAVs in the railway industry and proposals for common UAV solutions based on functional requirements.

  • Scheibenflug, Sara
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.).
    Internal Pricing and theEffect of Liquidity Requirements: A qualitative review of Swedish banks2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The fundamental business model of banks is based on receiving short-term deposits and giving long-term loans which means that active banks are naturally subject to liquidity risk. During the last financial crisis poor liquidity risk management was seen as one of the main causes which has led to an increased focus on the management of liquidity risk and the introduction of the first minimum requirements for liquidity in banks, through Basel III. As the topic of internal pricing in banks and the effects of the introduction of the liquidity coverage ratio (LCR) and the net stablefunding ratio (NSFR) is not extensively covered by existing research, the aim of this thesis is to identify and discuss internal pricing and liquidity cost allocation mechanisms used in practice bySwedish banks. The study also aims to investigate the impact of changes in liquidity requirements on internal pricing and liquidity cost-benefit allocation mechanisms in a Swedish setting.

    The key findings are that firstly, there are large variations regarding the sophistication of banks funds transfer pricing practices and liquidity cost allocation methods. The banks using less sophisticated methods may be exposed to model risk if they themselves are not aware of the implications of this. Two consequences of using simplified approaches may be distorted assessment of profitability and unwanted maturity transformation. Secondly, the findings indicate that the link between risk management and internal pricing in the banks is rather weak. Lastly, the introduction of LCR and NSFR have had a significant impact on the bank's risk management but the effect on internal pricing practices and methods for allocating liquidity costs is very limited.

  • Sved, Sofia
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematisk statistik.
    Quantification of Model Rrisk2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The awareness of model risk has increased due to the increased use of models to valuate financial instruments and their increasing complexity and regulators now require financial institutions to manage it. Despite this, there is still no industry or market standard when it comes to the quantification of model risk. The objective with this project is to find and implement a method that may be used to quantify model risk and evaluate it based on accuracy, efficiency and generalizability. Several approaches to model risk in the literature are explored in this thesis and it is concluded that existing methods are generally not efficient, accurate or generalizable. However, by combining two of the existing methods in the literature and using data on counterparty valuations, another method to quantify model risk can be constructed. This method is implemented and backtested and it is found to be accurate, general and more efficient than alternative approaches. Furthermore, this method may also serve in model validation as a mean to judge the quality of valuations and compare valuation models to each other. One limitation of the method is that if there are few counterparties for a valuation model, say 1 or 2, the method used in this thesis is not suitable.

  • Romulus, Puja
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    In Situ Fabrication of Nanoporous Alumina into a Microwell Array2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Existing method for the antibiotic susceptibility test (AST) requires 2-3 days to produce the result. For patients with urinary tract infection (UTI), this lengthy process is critical because they must bear the pain during this period. A newly proposed idea to shorten the time is by using phenotypic antibiotic susceptibility test (AST) method on single bacteria.The first step to achieve the goal is to design and fabricate a platform to capture single bacteria and remove unwanted particles. An integrated micro and nanomembrane structure fulfill the requirement. The micro membrane structure is used to capture intended particles and block larger particles, while nanomembrane is used to remove unwanted nanoparticles. Micro-membrane structure is designed as an array of the microwell, and each microwell is expected to capture the bacteria. The thickness of microwell must be comparable to the bacteria dimension to make the observation of single bacteria be possible. Otherwise, there will be a stack of bacteria and only the bacteria at the top can be observed.The nanoporous membrane is created using aluminum foil through the anodization process and microwell structure is created using OSTE polymer through photolithography. Both materials are inexpensive and the fabrication process is fairly simple. In the final result, the nanoporous membrane is successfully integrated with microwell array. Each microwell has diameter 200 µm and thickness 100 µm. The nanoporous membrane has pore diameters 70nm, thickness 200nm, and approximate porosity 24.6%.This project successfully produces a complete device by integrating microwell array, nanoporous membrane, and a device substrate. However, the desired thickness for the microwell array is not achieved. The thickness of the microwell is 100 µm while the size of a bacteria is only a few microns. Thin microwell array with 5 µm thickness is easily detached from the substrate during development. To solve this problem, a different mixture of developer solution is needed that will develop the OSTE but will not destroy the structure. Nevertheless, this early design of the platform is a promising start in the early development of rapid antibiotic susceptibility test (AST).