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  • Niu, Chang
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Numerical Study on PollutantRemoval Performance of Island Kitchen Exhaust Devices2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It is reported that cooking can generate many kinds of airborne pollutants,which pose serious threats to human health. Kitchen range-hood is themost effective and popular equipment to exhaust the airborne pollutants,including smoke and oil particle in people’s daily life. The lack of astandardized and overall approach to test and evaluate range-hood makesboth consumer and some manufacturers confused. For these reasons,Lawrence Berkeley National Laboratory published a report, whichshowed the results of their elaborate experiment and some conclusion.However, they also pointed out that due to the limitation of the apparatus,some of the results are not reliable.Therefore, this project established a numerical model in Fluent toinvestigate the pollutant removal performance. Many attempts had beenmade before a validated numerical model was accomplished because aproper model needs the balance between iteration time and resultaccuracy. The validation part is presented in the literature. The captureefficiency curve of the numerical model and one of experiments show agood agreement at the low power input. Some conclusions are drawn onhow power inputs and height affect the capture efficiency, respectively.Dimensionless analysis is done to find a general characteristic curve forevaluating the removal performance of a particular range-hood.

  • Public defence: 2019-03-14 10:00 B242, STOCKHOLM
    Williamsson, David
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    On integrated modularization for situated product configuration2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Road transports face increasing societal challenges with respect to emissions, safety, and traffic congestion, as well as business challenges. Truck automation, e.g. self-driving trucks may be utilized to address some of these issues. Autonomous transport vehicles may be characterized as Cyber-Physical Systems (CPS). A drawback is that CPS significantly increase technical complexity and thus introduce new challenges to system architecting.

    A product architecture is the interrelation between physical components and their function, i.e. their purpose. Product architectures can be categorized as being modular or integral. The main purpose of a modular architecture is to enable external variety and at the same time internal commonality. Products with a modular architecture are configured from predesigned building blocks, i.e. modules. A stable module, which is a carrier of main function(s) has standardized interfaces, is configured for company-specific reasons, which means it supports a company-specific (business) strategy.

    In this thesis, the present state at the heavy vehicle manufacturer Scania, concerning product architecting, modularization, product description and configuration is investigated. Moreover, a new clustering based method for product modularization that integrates product complexity and company business strategies is proposed. The method is logically verified with multiple industrial cases, where the architecture of a heavy truck driveline is used as a test bench. The driveline contains synergistic configurations of mechanical, electrical and software technologies that are constituents of an automated  and/or semi-autonomous system, i.e. the driveline may be characterized as a CPS. The architecture is analyzed both from technical complexity and business strategy point of view. 

    The presented research indicates that a structured methodology which supports the development of the product architecture is needed at Scania, to enable control of the increasing technical complexity in the Cyber-Physical Systems. Finally, configuration rules are identified to be highly important in order to successfully realize a modular product architecture. A drawback with this approach is that the solution space becomes hard to identify, therefore a complete and flexible product description methodology is essential. The results from the case studies indicate that clustering of a Product Architecture DSM may result in a modular architecture with significantly reduced complexity, but with clusters that contain conflicting module drivers. It is also identified that the new modularization methodology is capable of identifying and proposing reasonable module candidates that address product complexity as well as company-specific strategies. Furthermore, several case studies show that the proposed method can be used for analyzing and finding the explicit and/or implicit, technical as well as strategic, reasons behind the architecture of an existing product. 

  • Arnesson, Erik
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Analysis of sustainable building materials, their possibilities and challenges2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The palm oil agroindustry not only produces the most consumed vegetable oil in the world but also a significant quantity of residual biomass waste. The importance of using some of these by-products for energy production is widely understood. However, palm oil mill effluent (POME), the residue which is responsible for the highest share of GHG emissions in palm oil production, is usually disposed of in an unsustainable way. Methane emissions from POME degradation, in a conventional palm oil mill, are responsible for more than half of the greenhouse gases emissions in the production process (excluding land use change). This research aims at investigating alternatives to retrofit Indonesian palm oil mills into biorefineries that could efficiently exploit POME to produce value-added products (e.g. electricity, compost and pellet) while decreasing the environmental impact. In this research, the author presents a literature review of commercially mature treatments for POME and biomass residue highlighting the most promising ones. Subsequently, biorefinery concepts are created by combining the selected technologies aiming at maximizing revenues and social impact while decreasing environmental impact. For each biorefinery concept is performed a sustainability assessment calculating a set of indicators representing economic, environmental and social impact. The multi-criteria analysis is applied to combine in one single index the information obtained by the sustainability assessment. This method allows identifying the solution offering the best trade-off while integrating into the decision process stakeholders’ point of view. The results show that avoiding methane emissions from untreated POME can be done in a profitable way while generating at the same time positive social impacts. The emissions reduction of the proposed biorefinery concepts demonstrates savings from 67% to 109% compared to the conventional system. Furthermore, all proposed biorefinery concepts proved to be economically and socially sustainable. The best results have been obtained by a biorefinery concept that produces electricity from the methane captured from POME degradation to produce high-value products such as pellet from biomass residue and crude kernel oil. The same optimal solution has been found for off-grid palm oil mills even though they tend to favour solutions with simpler layouts. In conclusion, the research demonstrates that biorefinery concepts are an opportunity for mill owners to comply with the strictest environmental regulations while producing extra profits and positive social impact.

  • Hosseini Moghaddam, Seyed Mazyar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Designing battery thermal management systems (BTMS) for cylindrical Lithium-ion battery modules using CFD2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Production Engineering.
    Wendel, Olivia
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Cirkul¨ar ekonomi inom produktion av solcellssystem2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Solar technology is the most promising source of renewable energy. The market for solar cells is growing rapidly and it is therefore of importance that the solar industry develops in a sustainable way. This report examines how the photovoltaic industry can be adapted in accordance to the principles of a circular economy. The focus is on implementation of a circular economy in the production of solar panels and within the business of installation of solar systems. This has been done through a literature study of the production of solar panels. The installation process of the solar cell system has been studied via interviews with the CEO of Susen AB, a Swedish installation firm. The result discusses what measures need to be taken in solar cell production and in the business of an installer of solar cell systems, to fulfill The Ellen MacArthur Foundation’s three principles of a circular economy. The results show that in order to achieve a more circular economy the most important work lies in the management of used solar cell systems. Recycling stations specialized in the management of used solar cells need to be formed. Silicon extraction is the process that requires the most energy in the production of solar modules, therefore recycling of silicon from end-of-life solar cells is of special importance for a circular economy. The problem found with establishing solar panel recycling stations is that, because the technical lifespan of solar cells is so long, there is currently a too small amount of used solar cells in order for any operator to find it profitable to conduct such a business. The biggest difficulty with implementing circular economy in the solar cell industry is the fact that the supply chain is very dispersed. Therefore, in order to implement a circular economy, collaborations between the various actors need to be formed, preferably by industry standards for how production, assembly and management of end-of-life solar systems should work in accordance to the principles of a circular economy.

  • Nyari, Judit
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic feasibility study of a methanol plant using carbon dioxide and hydrogen2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lundström, Sara
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Svensk textil- och konfektionsindustri: en analys av branschens framtidsutsikter2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The textile and clothing industry was an important part of the Swedish manufacturing industry during most of the 20th century. The industry suffered from setbacks during the 70’s and the line of business nearly disappeared. The knowledge about textile and clothing production that had been built up for decades disappeared along with the line of business. One of the largest challenges of the industry today is the lack of workers who possess the right competence and are willing to work within the manufacturing industry. Another challenge is the difference in production cost between high and low wage countries. This is due to the difference in wages, environmental laws, accessibility and price of raw material and other fixed costs. A growing trend that can be seen globally is a growing number of companies evaluate the possibility of moving their production back to the origin country. The wages are on the rise in developing countries and the consumers of today expect higher quality, flexibility, and social and environmental sustainability. By moving production back, the companies can shorten lead times, increase flexibility and at the same time build their brand. The question is; will the Swedish textile and clothing industry follow this trend? The companies who have been successful in having production in Sweden are those with a niched and high-quality product. However, it is not an obvious choice for these companies to keep production in Sweden. Our work has led us to the conclusion that the type of textile and clothing industry that has chances of returning to Sweden is not the same as the one that once disappeared. If the right investments are made we believe that Sweden can be successful in highly atomized production of innovative textiles.

  • Agarwal, Rohit
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    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 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Head-up display (HUD) has a proven track record in the aviation and automobile sectors, allowing pilots and drivers to access information without diverting attention from the outside world. Similar benefits may be realized by the installation of HUD in locomotive cabs.

    The objective of this thesis work is to develop the user interface for HUD based on the ERTMS system. The HUD will be an added safety feature to the trains to prevent drivers from refocusing between the instrument panel and the outside view thus leading to reduced driver fatigue and better observation of the tracks ahead. Scenario Based Design method has been used to implement the project work with discussions regarding its advantages and limitations. The use of scenarios has allowed the design team to understand the scenarios that the drivers face in depth and has aided during the workshops to understand the drivers’ routine better.

    Additionally, recommendations for the hardware, installation and future work have been provided to support further implementation of the project.

  • Razzetti, Elisa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Potential for Seasonal Electricity Storage in Borehole Thermal Energy Stores with Heat Pumps2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Production Engineering.
    Törnered, Elisabet
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Design av tvättmaskiner för ökad cirkularitet2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the economic growth of today, both living standards and the consumption rate in society increases, which leads to an accelerated exhaustion of resources. As a consequence, the risks that follow the traditional, linear economy are accentuated since it is based on the assumption of unlimited resources. With these challenges, the idea of a circular economy has emerged. The aim is to create a long-term sustainable cycle, where both components and materials are kept in closed loops of which the inner ones should be prioritized. In this report, the included loops are Maintain/Prolong, Reuse/Redistribute, Refurbish/Remanufacture and Recycle. This degree project aims to investigate how to appropriately apply the concepts of circular economy to washing machines. To achieve this, three questions are raised and discussed so that a conclusion on how washing machines should be designed to fit the concept of circular economy can be drawn. These questions cover the following topics: which design parameters of the washing machine have the largest impact on circularity, the current appliance of the loops as well as incentives and obstacles for circularity. The approach is to combine theory with empirical data through an initial literature study followed by four interviews with different operators of the value chain: Miele, Electrolux, Hushållsservice Söderort AB and El-Kretsen. Our recommendation is to design washing machines for easy disassembly, using carefully selected materials. Moreover, the products should be designed for long-life with the possibility of product life extension as well as upgradability of components and software. These solutions concerning the design are all essential for increasing resource efficiency, which is why we cannot exclusively recommend either one of them. Furthermore, modularisation was investigated as a design solution, but in order to make a recommendation a deeper analysis than the one presented in this report would be required. However, for an increased circularity to be realistic, further measures that do not concern the product design are necessary. For efforts to be made by companies, they must be encouraged through financial incentives. These could be generated as a result of promoting legislation, progress in research and development and increased customer demand.

  • Ramirez Gomez, Camilo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Production Engineering.
    Stipic, Susanne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Återtillverkning av fordonskomponenter: En komparativ studie av den svenska marknaden2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The linear “take-make-dispose” production process has long been the dominating form of production. This production model is dependent on a steady supply of raw material that is processed into goods, which are then consumed and discarded. However, the dwindling raw material reserves are causing sustainable production processes to become more important for producers, resulting in the emergence of various methods for reusing materials and discarded products. This is especially noticeable in the automotive industry. Remanufacturing, the process of restoring a discarded product to its original state, is a growing area of interest for both original equipment manufacturers and independent remanufacturers. The objective of this report was to evaluate remanufacturing of automotive components on the Swedish market. This was done by surveying companies related to remanufacturing. A comparative study of two remanufacturers, Volvo Powertrain in Flen and Borg Automotive, was also performed. Additionally, the remanufacturing difficulties found in theory were compared to the difficulties expressed by the surveyed remanufacturers. The result of this project showed that remanufacturing is not a widespread practice in Sweden. However, the surveyed companies have a positive attitude towards remanufacturing and consider it to be a growing industry. The obstacles for remanufacturing found in theory were found to be valid in practice. These obstacles are inventory build-up, insufficient access to discarded components, and difficulties automating the remanufacturing process. The operations of original equipment remanufacturers and independent remanufacturers were found to differ from one another and therefore the companies face different types of obstacles. Moreover, high barriers to entry make it difficult for new companies to emerge on the market. There are also weak legal incentives for companies to start remanufacturing. Instead remanufacturers are primarily driven by financial incentives. Another obstacle, not identified in the theoretical framework and experienced by the original equipment remanufacturers, is the matching of supply and demand. In conclusion, the theoretical framework is largely consistent with the observed practice. This indicates the remanufacturing is well understood in the academic literature. The problem of matching supply and demand should be examined more closely in future studies, as there is no theoretical foundation for this problem. Overall, there is a positive outlook on remanufacturing and the companies involved work actively to both promote remanufacturing as a practice and develop solutions for the problems they face.

    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Ledtidsreduktion med hänsyn till kapitalbindning: Vägen mot minskad ledtid och kapitalbindning i Lantmännen Cerealias pastafabrik2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Due to the prevailing food trends, customers demand premium goods such as organic and low carb products in addition to simpler alternatives. The trends puts pressure on food businesses to offer a wide selection of products, which leads to an increasing need for efficient supply chains as well as decreases in capitalization. Value stream mapping is a tool used to identify wastes. These wastes increases lead times in a production flow. The results gathered from the analysis can be used to compare value adding time with non-value adding time, in order to discover processes that drives up expenses without adding value for customers. Detailed analysis of these processes can identify possible reductions in capitalization, through reduced levels of work in process and stock. Capitalization can also be reduced by ABC classification of products. The purpose of this thesis is to examine how value stream mapping can help reduce lead times at Lantmännen Cerealias pasta production plant in Järna. Reduction of capitalization through reducing the amount of work in progress and stock is also studied. Furthermore, the effects of ABC classification are examined in order to ease fluctuations in demand and reduce capitalization at the plant. The conclusion answers whether or not it is possible to reduce the lead time in the production and simultaneously reduce capitalization. Value stream mapping proved to be an efficient tool to identify possible sources of waste and improvements in the production. In this case, the absence of accurate numbers made the analysis challenging and led to inaccurate results. The parameters used for the ABC classification led to a proper partition of products since it took both fluctuations in demand and problems regarding capitalization into account. This partition of products is assumed to reduce both capitalization and ease the effects of fluctuations in demand. Reducing the storage time of WIP using value stream mapping can result in reduced levels of WIP. Reducing WIP to the lowest possible level proved to be impossible in the short term. However, the possible reduction of WIP levels would result in reduced capitalization. The most important conclusion drawn from the analysis, is that a reduced lead time often has a positive impact on capitalization. Transformation of stockkeeping proved to be of great importance when reducing both lead times and capitalization. Since the value of finished goods are higher than the value of WIP, reducing storage time for inventory of finished goods proved to have a greater impact on capitalization.

  • Fournis, Camille
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Study of tip clearance flows2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • Public defence: 2019-10-26 00:00
    Betts, Abdul
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Mortgage funds: Examining the emergence of new mortgage finance methods in Sweden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Simulation of Hardening of the MahanaKhon Tower Mat Foundation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    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 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    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 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    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 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Dagsljus i stadsplaneringen: En fallstudie i Norra Djurgårdsstaden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • Public defence: 2019-03-22 10:00 Science for Life Laboratory, room Air & Fire, Solna
    Svedberg, Gustav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Novel planar and particle-based microarrays for point-of-care diagnostics2019Doctoral thesis, comprehensive summary (Other academic)
    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.

  • Public defence: 2019-03-15 11:00 Salón de Grados, San Sebastián, Spain
    Blanco, Blas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Development of new techniques for the numerical modelling of railway track dynamics. Application to rolling noise assessment2019Doctoral thesis, comprehensive summary (Other academic)
    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, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Design of Reliable Lightweight Cast Components: An Optimization Driven Design Appraoch2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Production Engineering.
    CFD Simulation of MQL with low temperature and high-pressure coolant2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Employing huge amount of cutting fluids in machining process has potential negative impacts not only to the operator but also to the environment along with increased cost of manufacturing process. To reduce the cutting fluid consumption during machining, a technique called Minimum Quantity Lubrication (MQL) is introduced which uses very less amount of cutting fluid yet being effective than flood cooling. This thesis focuses on determining the convection over a cutting insert with a constant heat source inside a square enclosure and the computational domain of the CFD model presented consists of fluid and solid domains with fluid-solid interaction. The feasibility of MQL using low temperature and high-pressure coolant and observing how temperature is dropping after the application of coolant/coolants by simulating the conditions in ANSYS fluent workbench. The effectiveness of this technique is determined in terms of whether high pressure and low temperature coolant can dissipate heat and remove chips from the cutting interface. Finally drawing conclusion based on results.

  • Yousif, Robert
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    A Practical Approach of an Internet of Robotic Things Platform2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    Opportunities for small-scale anaerobic digesters for hotels and restaurants in Kathmandu, Nepal2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    The Electricity Model for China – Insights and Implications of Energy Policies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    Förnybar energi-driven membrandestillering för rening av dricksvatten: Main Ethiopian Rift Valley fallstudie2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    Comparison of solar thermal and photovoltaic assisted heat pumps for multi-family houses in Sweden2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • Public defence: 2019-03-14 10:15 F3, Stockholm
    Karlsson Hagnell, Mathilda
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Technical cost modelling and efficient design of lightweight composites in structural applications2019Doctoral thesis, comprehensive summary (Other academic)
    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, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    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 credits / 30 HE creditsStudent thesis
    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, School of Electrical Engineering and Computer Science (EECS).
    Embedded programming and construction of the PCB SiC In Space Experiment2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Utveckling av gasutbytesmodellering och reglerstrategi för spark ignited engine2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Government legislators constantly increasing the demands on controlling the emission from heavy-duty vehicles for maintaining sustainable environment. At the same time, from the customer's perspective, a much needed demand for fast response and minimal fuel consumptions is also increasing. To get the desired torque, the control architecture has to be made robust and fast by using optimal air mass flow and EGR rate into the cylinder by maintaining the Air-Fuel Ratio (AFR) at stoichiometry at all operating regions. In order to maintain the temperature and pressure in the exhaust manifold, Exhaust Gas Recirculation (EGR) valve has been introduced in the spark- ignited engines which feeds back the burned exhaust gases into the intake manifold. In this thesis, a Model-based control algorithm has been developed by modelling throttle, EGR and waste-gate actuators with cross sensitivities. The algorithm aims at achieving the requested air flow and EGR rate as fast as possible during the transients at all operating points (Engine Speed and load). To evaluate the control strategy, a five-cylinder engine was modelled in GT-SUITE software. The model-based controller algorithms is designed in SIMULINK by establishing a communication link using Functional Mock-Up Interface (FMI). The Model-based controller is pre-fed with a pre- filter/pre-controller using Gain Scheduling PID algorithm which is integrated to form a closed loop cascade controller. Series of analysis has been done in transient domain by varying the load requests and the operating points (Engine Speed). The algorithm that is developed gave satisfactory results where the response time has been increased and the oscillations are damped to a greater extent.

  • Ingvarsson, Gustaf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Assessment of a Thermal De-Icing Solution and Control Methods using Simulations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    t has been discovered that trucks driving in Nordic winter conditions run the risk of the headlights, and other lights, getting covered in ice and snow. This prevents the lights from illuminating he roads. It has previously been solved by excess heat from the light bulbs, with the recent change to LED lights this problem has escalated. The headlights are now in need of a de-icing system capable of removing ice and snow, as well as preventing it from building up on the lenses.

    This thesis project carried out at Scania CV, Södertälje, deals with the controlling method for a thermal de-icing solution. The main task of the project was the development and use of simulation model for a chosen heater solution. On this model two developed control methods were compared.

    In order to find a suitable thermal solution, the three different modes of heat transport were investigated and a solution for each mode was compared against each other. The best solution found was resistance wires molded into the lens, this due to being near the ice and having the most efficient mode of transfer. This solution was incorporated into a simulation model, that described the heat transfer process of a lens covered in ice.

    Two control methods were chosen based of a literature research, a hybrid controller using gain scheduling and a second hybrid controller using a smith predictor. These were implemented into the simulation model and their performance compared. The smith predictor had the better performance out of the two, being generally faster and has less overshoot. The method does have problems with feedback disturbances, requiring filters in real life implementations. The control method using smith prediction is the one recommended for future work on this project. Before implementation on hardware work needs to be done regarding filtering.

  • Lions, Alexandre
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    IMPROVING THE REPRESENTATION OF 1D PERFORMANCE COMPRESSOR MODEL2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • Public defence: 2019-03-22 10:00 Gladan, Stockholm
    Tasala Gradin, Katja
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). KTH.
    Methodological Simplification in Comparative Life Cycle Assessment and Consequences on Validity2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Life Cycle Assessment (LCA) is central to the development of sustainable products. LCA assesses the environmental impact of a product, service, or system through-out its whole life cycle, from material extraction to end-of-life phase. A comparative LCA compares alternative product-systems, or compares an existing product-system with a proposed redesign. All system parts that are identical between the compared products can be omitted from the LCA, and only those that differ need to be assessed. This simplification is called comparative LCA with omitted parts.

    Valid results from LCAs are of high importance for decision support in areas such as choice of materials, manufacturing processes, and waste management. The validity of the LCA results is especially crucial to avoid sub-optimal and rash conclusions.

    The purpose of this thesis is to investigate LCA simplification in order to gain knowledge and understanding of its effects on the validity of LCA results.

    Four appended papers present five different levels of omission in comparative LCA transport case studies. The LCA models and simplifications are analysed against a defined isolation criteria checklist. The list is a guide to identifying the simplification, motivating the omission, and reasoning about the potential implications of both the omission and isolation.

    The results show that to omit parts and exclusively assess only an isolated part does affect the model validity. The internal validity is strengthened and supports a more apparent cause-effect relationship that can help explain the conclusions and the recommendations of LCA. The external validity is weakened with lower generalisability of the result, especially from a long-term perspective.

    There are further research opportunities within this area concerning the practical implications, investigations in other contexts, e.g. the biofuel industry, agriculture, and the building sector, and further quantitative studies. One of the practical contributions of this thesis, the isolation criteria checklist, could be developed into a more general guide for LCA practitioners.

  • Öström, Linn
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Post-processingof Monte Carlo calculated dose distributions2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    A review of energy modelling tools2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Modeling contingency infiltration scenarios in MODFLOW: Stockholm Bypass and tunnel induced groundwater drawdown2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    Circular Economy in Cities: Framework Development & Porto (Portugal) Case Study Analysis2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Residual stresses in Ti-6Al-4V from low energy laser repair welding2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Minute defects may occur in large complex Ti-6Al-4V castings, sometimes these are unnoticed until after machining and a high cost has been sunk into the part. These defect and other potential manufacturing mishaps render a need for additive repair methods. The state of the art method TIG welding can repair the parts but may leave unacceptable residual stresses, where the state of the art solution of Post Weld Heat Treatment might create a surface defect known as alpha case. Therefore there is a need for a repair weld method that results in lesser or negligible residual stresses.

    This thesis, carried out at GKN Aerospace – Engine Products Sweden, Trollhättan analyses the potential relationships between the laser welding parameters Power, Spot size, and Weld speed and the resulting residual stresses in a low energy parameter area on the material Ti-6Al-4V.

    A parameter box of 17 parameter sets was established, laid down and analyzed under micrograph, of this box the outer 8 parameter sets were simulated via the Finite Element Analysis welding simulation software MARC and a relationship between the input parameters and their resulting residual stresses was analyzed.

    A statistically significant trend was found supporting the claim that a decrease in transversal stresses in the center of a 20mm weld line is caused by an increase in Weld speed. This has implications for welds using run-on & run-of plates.

    It was also noted that an increase in Power or Spot size, or a decrease in Weld speed increases the area under residual stress; both as individual parameters and in synergy. This has implications for Post Weld Heat Treatment in determining the size and shape of the area in need of treatment.

  • Enefalk, Tommy
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Improvements to Thermal Management System for Automotive Components2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    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 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Energy Technology.
    Open Source Energy Model for the Electricity Sector of Sri Lanka2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    UAVs for railway infrastructure operations and maintenance activities2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.