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  • Harlin, Anna
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Malongen: a mimic of a rock2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Malongen consists of two volumes containing housing, a gallery, and a restaurant. The design language of the base comes from a 3D scan of the rock 30 meters north of the plot. The buildings are a design interaction to explore the tension between the historical mountain cut and a design interaction. With a digital imitation of the rock the buildings intend to mimic the surrounding area. The rock, that is the historical imprint of the place, is now translated into buildingelements, as a result of my manipulation of the file. This project has investigated how we can create a contemporary buidling that refer to a historical site and keep telling a story about time.

  • Grundmark, Anna
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    ”VART ÄR VI PÅ VÄG?” / WHERE ARE WE GOING?2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the middle of the nineteenth century, the train came to Sweden. It has been just over 150 years and a lot has happened. With the train and its station came more then just a means of transportation, it turned Sweden from a developing country into one of the most modern. In the small Swedish cities and on the countryside, the stations became a central node, a meeting point and a place to gather. The train passed through previously isolated areas where the stations became not only just that but also a window towards the rest of the world. This project is a study of the Swedish train station and a humble proposal on how to treat them, what to do with them and when to do it (now).

  • Svensson, Daniella
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Ribbefjord, Beatrice
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Ekonomiska fördelar med en grön premie: En studie av ekonomiska drivkrafter på den gröna obligationsmarknaden i Sverige2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report aim to examine and analyze motives and financial incentives behind the real estate sector's participation on the green bond market in Sweden. The report discusses whether a Green bond premium, also called Greenium, exists and how large it is. Furthermore, the reasons why a Greenium can occur are analyzed. A discussion about whether it is more economically viable to trade in green bonds compared to ordinary corporate bonds is implemented. In 2007, the World Bank issued the first green bond in the world in cooperation with SEB. Since then the market has grown to a global value over $ 300 billion. Vasakronan issued the world’s first green corporate bond in 2013 and since then the green bond market in Sweden has grown strongly. Green bonds have the same economic traits as traditional bonds, but the difference is that revenues from green bonds must finance environment or climatefriendly projects. Green bonds entail some risks for active issuers and investors. These risks include reputation risk, greenwashing and asymmetric information. Given the enormous impact companies have on the environment, it is appropriate for companies to take responsibility for their emissions and other negative external effects. Through the concept Corporate Social Responsibility companies have taken more responsibility for how they affect society from both an economic, environmental and social perspective. Through CSR green bonds have become popular and especially on the real estate market, where the ambition of sustainability has grown strongly in recent years. In conclusion, it can be stated that a greenium exists but that it is difficult to estimate. According to interviewed issuers in the real estate sector, greenium can be assumed to be -4 to -5 basis points and, according to scientific articles, it is assumed to be about -2 basis points. The fact that greenium arises depends on investors’ large demand and issuers' low supply of green bonds at present time. The real estate industry is the leading sector in the green bond market in Sweden and this is assumed to be due to the industry's early modification of green bonds and the sector's well-developed certification system of sustainable buildings. In the future, the green bond market can be assumed to grow and develop in both other industries and other countrie

  • Nielsen, Carl
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Osäkerhet och risk vid bedömning av restvärdet för Samhällsfastigheter: En fallstudie av hur fastighetsvärderare hanterar restvärdet för samhällsfastigheter2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Currently, there is strong investor demand for public property in Sweden with yields declining for both prime and secondary segments of the market. The underlying demand for properties relating to education and elderly care is expected to be high for years to come as a result of a growing population and other demographic changes. Investments in public property is considered low risk due to the long-term leases with financially strong and stable tenants. The occupancy rate for public property is high, partly due to the fact that single tenant properties are a regular occurrence and partly because the high demand. All investments are associated with risk, the character of which varies depending on the type of property and various other factors. Technical risk, political risk and environmental risks to name a few. Public properties are, per definition, properties that primarily houses tax-financed operators and that is customized for public services. Because of the specialized nature of these assets and the fact that they are difficult to convert to other uses the question of risk and uncertainty arise at the end of the lease period. When valuing a property using the discounted cash flow method this moment in time in when the terminal value is evaluated. The aim of this case study is to examine how valuers assess the risk and uncertainty associated with the terminal value of public property in Sweden. Through analysis of the external valuations that have been undertaken at one of Sweden’s largest owner of public properties for the end of year 2018 the objective is to find factors related to the terminal value that differ between properties intended for educational purposes and those for elderly care. By conducting interviews with external valuers, the report will outline what aspects of a property valuers examine in determining the terminal value. Information gathered in the interviews will be used to analyze the valuations that were carried out for the end of year reporting of Sweden’s largest owner of public property. The report starts with a review of the fundamentals of valuation which later in the report will be applied to the empirical data to create a framework from which determination of the risk associated with the terminal value of public property can be judged. Furthermore, the report will seek to understand the bridge between theory and practice in the subject.

  • Myhrer, Samuel
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Effekten av infrastruktursatsningar på bostadspriser i närliggande områden: En studie om Nacka stad. Prisutveckling i Jarlaberg och Storängen2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nacka municipality is undergoing major changes because of the project Nacka stad, which involves new housing, commercial properties and metro stations. When an area within a municipality changes, it has been shown that this influence housing prices in other neighboring areas. The aim of this study is therefore to see what effect infrastructure investments have on housing prices in Jarlaberg and Storängen, because of the project Nacka stad. This has led to the framing of the question; Which effect will the Nacka stad project have on housing prices in Jarlaberg and Storängen? The study is based on theories of property valuation, price, location and residual evaluation. Two types of data collection have been used; Booli and a survey. In addition, literature studies have also been carried out. The result shows that Nacka stad will have a positive effect on housing prices in Jarlaberg. Regarding Storängen, there is not enough relevant data and information to be able to draw any conclusions.

  • Jillersberg, Madeleine
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Denlert, Adam
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Finansiering inom bostadsrättsektorn: En studie om en alternativ finansieringsmodell2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Prices on the Swedish housing market has risen the past few years. A consequence by this is that an increasing amount of people struggle to buy their first apartment. In particular people that want to buy their first apartment, which struggle to save enough money for the cash deposit or to get a big enough loan from the bank. In an attempt to solve this, an alternative financing in the condominium sector has been introduced to the market in an attempt to make it easier for people to afford buying their first condoninium. This report aim to compair a condominium that has been funded through the tradtional way and a condominium that has been funded through this alternative way. A survey has been conducted in an attempt to investigate the knowledge whom people that is about the buy their first condoninium possess. An interview has also been conducted to further strenghten our findings from the survey and to get a deeper understanding about this alternative concept. The results indicate that people that’s never bought an apartment before lack some essential knowledge that you need to possess when you buy in apartment in order to make the right choices. This alternative financing might give an opportunity for some people to buy their first apartment, an opportunity they otherwise might not have.

  • Göthlin, Sanna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Rigogianis, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    IFRS16 - Leases2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    By 1st of January 2019 the new International Accounting Standard IFRS 16 - Leases will be applied and replace the old accounting standard IAS 17 - Leases. The classification between an Operational Lease and Financial Lease according to IAS 17 – Leases, has received criticism for creating an incentive for corporations to account for a lease contract as an operational lease and therefore avoid capitalizing the contracts in the balance sheet as a right of use asset and lease liability. To cope with the complex of problems, as well as the information asymmetry that arose, IASB and FASB initiated a project that lead to the new accounting standard IFRS 16 - Leases.To elucidate in the new standard IFRS 16 is the fact that the lessor is not affected in the same extent as the lessee. The lessor method for accounting reminds of the previous standard IAS 17 and therefore the alteration does not cause any major changes. For the lessee IFRS 16 implies that the corporates must identify their lease contracts with a duration past twelve months and leased assets with a value above 5 000 USD when new. Hence the classification of operational and financial lease contracts will be eliminated for the lessee but remain for the lessor.The purpose of the thesis is to study the effects of IFRS 16 on real estate companies income statement and balance sheet through a qualitative approach with interviews in combination with a quantitative analysis of the financial quarterly reports for January to March 2019. Henceforth a clarification of financial ratios affected by IFRS 16 will be provided and lastly the study will examine if IFRS 16 may affect the valuation of properties provided with a site lease. The purpose of the thesis is formulated into two questions mentioned in section 1.3 Aim.Based on the interviews conducted with representatives from three different areas of activity, 

    relevant conclusions have been presented and the research questions have been answered with certainty. The transition to IFRS 16 affects key ratios such as loan-to-value, equity ratio and interest coverage ratio. For real estate companies, it is primarily leasing contracts in the form of site leasehold rights that are of importance as the real estate companies in these leases are lessees and thus are affected by the changed accounts. The gross profit will also be affected when the companies net operating income increases as a result of the fee for the site leasehold right, being moved from a cost that is charged in the net operating income to be a financial item in the form of interest.In conclusion, the study has ascertained that IFRS 16 - Leases do not affect real estate companies at large, neither on their financial reporting or specific financial ratios. It is relatively simple for the corporates to apply IFRS 16 through a simplified method, which a majority of the companies have chosen. However, it has emerged that is has not been an easy task to interpret the standard and how detailed information regarding IFRS 16 should be recognized in the quarterly reports. Therefore, there have been a significant difference between clarity as well as formation in the quarterly reports released in the first quarter 2019. A general opinion from several respondents have been that IFRS 16 entails extra work in the companies accounts but unfortunately does not lead to increased transparency, which was the basic idea why the new standard was developed from the beginning. Thus, it can also be stated that IFRS 16 does not fully achieve its purpose in increasing transparency.The study is henceforth written in Swedish.

  • Yilmaz, Rusen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Edlund, Viktor
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Hur påverkas direktavkastningskravet på kontorsfastigheter av makroekonomiskaförändringar?: En kvantitativ studie av sambandet mellan direktavkastningskrav och makroekonomiska variabler2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Swedish office market has over the last couple of years developed into a state of recordbraking prime rents at an all-time high and cap rates at an all-time low. The force ofdevelopment has been the favorable macro-economic conditions. This study aims toexamine to what extent the development of cap rates of offices in Sweden’s three largestcities, Stockholm, Gothenburg and Malmo can be explained by macro-economic changes. Apoint of interest is how these cities relate to each other and the economy. The issue is put ina generical state where factors specific to the markets get left out.With the support of empirical studies and economic theories, such as the 4Q model, theissue is worked by a selection of macro variables by processing of data and basic statisticalcalculations. The selected macro variables are: CPI, Repo rate, Government bonds 10years, GDP, Unemployment and OMXS30. Correlation calculations and linear regressionmodels are central tools in the quantitative work. The statistical calculations are performedboth with and without time lags on the cap rates for macro variables. In this way, the inertiaand cyclical nature of the property market are considered.The result, which is in line with previous studies, shows that the movement of cap rates overtime often can’t be explained only by macro-economic variables. Furthermore, it shows thatthere is no palpable difference between the cities when it comes to development of caprates. The result shows the importance of the multitude of data and the selection of variableswhen performing a regression analysis. With this said the study does demonstrate aconnection between the development of cap rates and the chosen macro variables.

  • Fiedorowicz, Sandra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Eklöf, Ellinore
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Bostadsföretagens uthyrningspolicy: En jämförelsestudie mellan bostadsföretag i Stockholmsområdet2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main focus in this thesis has been to examine different housing companies rental policy in Stockholm and to review how easily it is to maintain relevant information regarding the leasing process through the companies websites. We want to see if there is any difference between how the housing companies convey their demands and how this affects the person looking for a rental apartment. Furthermore, we want to see how everything above affect the society, especially students. Is there any difference between municipal housing companies and private housing companies in Stockholm?We analysed 13 websites belonging to different housing companies to find answers to our questions. The housing companies involved in the study are: HSB, Ikano Bostad, Wallenstam, Byggvesta, Rikshem, Willhem, HEBA Fastigheter AB, Svenska Bostäder, Stockholmshem, Familjebostäder, Micasa Fastigheter, Stadsholmen and Stockholms Studentbostäder. We studied how the different companies have decided to form their respective rental policy and how easy it is to find relevant information as an applicant. A comparison between the companies became possible with the gained information, the comparison gave us a clear picture of some recommended improvements within the field.It turned out to be a significant difference between the municipal rental companies and the private rental companies, where the private rental companies control their rental policies more strictly than the municipal rental companies. All of the housing companies’ websites were more or less weak in terms of availability and language possibilities. In the study we also covered the perspective of sustainability consider its significance for a further functioning society.In conclusion we provided recommendations for the housing companies in order to improve their rental policies and their websites. In our opinion should most effort be put on improving the opportunities for all individuals on the housing market to receive a residence. The housing companies’ websites should be improved with regard to transparency and language possibilities, to develop the housing market from a social and technologic perspective.

  • Paul, Sourav
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Sarkar, Saranik
    KTH, School of Industrial Engineering and Management (ITM).
    Integration of Cryogenic Machining Technologies in Advance Manufacturing Systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Conventional cutting fluids are an absolute necessity in today’s manufacturing domain, butthey are a polluting and non-sustainable part of modern manufacturing processes. These conventional cutting fluids can be replaced by cryogenic cooling, which is an innovative and sustainable method which has been successfully implemented to produce aerospace products and have shown great success and great quality of finished products. But the implementation is the main obstruction as the volume of production in aerospace and automotive components is quite vast and implementation of cryogenic may pose an obstruction in maintaining the production flow. This leaves us with a large unexplored area for research specially in the implementation of the system in the existing system, which canhelp us get a seamless transition from conventional to cryogenic cooling. Some of the notable points that there is a need to investigate before one can go ahead with the implementationare factory layout, chip removal, raining of personal, safety, monitoring system, cost, time, implementation and integration, maintenance, source placement, mass scale supply and quality. In the first part of this work, a deep literature study has been done to know all the aspects of cryogenics and its implementation and factors that must be considered. In the second a discussion about the target industries has been made where use of cryogenic cooling has been considered. Also, a small discussion about the existing companies that provide this system has also been discussed. The room for improvisation is very large, and a lot of physical testing needs to be conducted before it can be successfully implemented.

  • Rickfält, Tea
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    From linear to circular water management: A case study of Sandön/Sandhamn2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Even though water is essential for all living beings, the way humans manage water is traditionally linear; extract, use and dispose. By doing so, many cities have partly disconnected themselves from the environment by existing beyond the local hydrologic system. A circular water system, which reuse water within the technical water system, has the potential to improve the status of the environment and reduce pressure on existing water resources. As such it is an approach that receives increasing attention. This study aims to investigate how a circular water management approach can reduce fresh waterconsumption and decrease the human pressure on water resources through a case study of the island Sandön/Sandhamn in the Stockholm archipelago. A literature overview which identifies circular water management strategies have been performed along with a situation analysis of Sandön. To identify and assess different options of reuse the framework of strategic environmental assessment have been used. In the case of Sandön, which have a high water-demand peak during summer, decentralised solutions for one of the largest water consumers is recommended. Reclaiming water from the wastewater treatment plant to, among other, flush toilets would also be favourable. Private homeowners could also beneficially implement reuse by flushing toilets with water used to wash hands or from showers. The study shows that circular water management provides an opportunity to reduce pressure on water resources and use them in a more efficient manner. The most crucial criteria for circular water measures success is public acceptance. It is also important to thoroughly map local conditions to identify the best suitable reuse measures as each location is unique.

  • Friefeldt, William
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Gullberg, Philip
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Nätcoaching som ett komplement till lösningsförslag: En undersökning av en ny digital lärmiljö genomundersökande relation2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The digital and technical development of the world have been large-scale and people’s day-to day life has changed immensely the last century. In contrast, the Swedish school system has not been seeing the same rapid technical development. As students’ results in mathematic sare declining an approach to battle this trend can be to apply this technological development on students’ studies in mathematics. Therefore, this thesis sought to ease students’ mathematics studies by creating a digital learning environment. By combining worked examples with online coaching the environment was created through the platforms Mathleaks and TalkMath. Then examine how online one-to-one coaching works in this environment. It also sought to analyse how students perceive this teaching environment and if it can be usedas a complement to worked-examples. The environment was created based on pedagogical theories such as Vygotsky's sociocultural perspective, coach theories, synchronous communication as well as theory around one-to-one online coaching. Two methods were used to gather data. First, the conversations were automatically stored in a database. Secondly, a survey was used to gather the students’ opinion of the teaching environment. The framework Relationship of Inquiry was used to analyse all conversations between students and coaches. Students were chosen from an upper secondary school in the ages of 15-18 where one of the authors worked. Results indicated that the teaching environment that was created was a good complement to worked-examples. The environment was shown to help student’s knowledge progression. This shows that digital teaching environments can be a valuable addition for students when studying mathematics.

  • Occhinero, Marco
    KTH, School of Industrial Engineering and Management (ITM).
    Hydrogen production from automotive waste via integrated plasma gasification and water gas shift.2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The growing amount of landfilled waste could pose a problem in many parts of the world due to the scarcity of landfilling space and environmental threats. In particular, automotive shredder residue (ASR) waste, a by-product of the dismantling of End of Life Vehicles (ELVs), has been proven to represent an issue in particular in the EU, where countries are struggling to compel to the directives that regulate this type of waste. At the same time, interest for hydrogen production methods is growing in the industries due to the advancement in fuel-cell technology for transportation and for power production.

    This study aims to investigate the performance of an integrated plasma gasification-hydrogen production system powered by ASR waste through the simulation of the process in ASPEN Plus. The investigation is focused on the potential for hydrogen production from ASR waste in terms of energy efficiency and quantity of hydrogen produced. The integrated system consists of an updraft plasma gasifier to generate clean syngas with high hydrogen content, a water gas shift reactor to furtherly enrich the gas of hydrogen content and a PSA unit to extract the hydrogen from the gas stream. The plasma gasification section of the model has been divided into four sub-systems that are drying, pyrolysis, char combustion and gasification, and melting. These four sub-systems are used to model the plasma gasification using the equilibrium method. On the other hand, the water gas shift reactor and the PSA unit have been modeled around experimental data. A Mass and Energy balance has been produced to understand the mass and energy flows within the system. The results show that the system is able to produce 238,5 kg/h of pure hydrogen from a feedstock of 2231 kg/h of ASR waste mixed with 89,2 kg/h of coke and 30 kg/h of limestone, achieving a 48% energy efficiency. Thus, the integrated system can achieve the production of pure hydrogen. The parameter study on the ER shows that hydrogen production and energy efficiency are higher at lower ER. On the other hand, increasing the SBR, while increasing the hydrogen content in the syngas, does not lead to higher hydrogen production at the system's output, causing a detrimental effect on energy efficiency. The findings of the study imply that ASR waste has the potential for hydrogen production when using a suitable treatment process.

  • Sverrisdóttir, Sunna Mjöll
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Stream Restorationand Mitigation of Nitrogen in the Hyporheic zone: Interpretation of tracer tests from Tullstorps brook2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Streams and rivers have been modified in the past centuries for agricultural purposes. The Baltic Sea suffers from problems regarding eutrophication. Regulations of point-sources have decreased nutrient levels, but for a scattered source of nutrient pollution, streams are important. One way of mitigating nitrogen is with coupled denitrification and nitrification processes when stream water is transported through flow paths in the hyporheic zone, an area in the stream sediments where groundwater and stream water mix. Tullstorps brook is an agricultural stream that flows into the Baltic Sea. It has had problems with high nutrient loads and poor water quality and has therefore been restored. The fieldwork in this project was conducted in Tullstorps brook in May 2019, where Rhodamine WT (RWT) tracer test and Hydraulic Conductivity (HC) measurements were done in 3 reaches, and compared to similar fieldwork since before restorations, during the summer of 2015. Two reaches in an agricultural setting that have been restored, Reach 4 and Reach 6, were measured, as well as a control reach, Reach 5, which is in a natural setting. The tracer tests indicated a significant decrease in the velocity in remediated reaches. The results of exchange velocity between the stream flow and the hyporheic zone suggest an increase after remediation of the reaches and the residence time seems to be decreasing simultaneously. When comparing the hydraulic characteristics, different stream flow during measurements was considered in a qualitative manner. The results of HC measurements show a decrease from 2015 to 2019 in the remediated reaches. In Reach 4 it decreased from 1.20E-03 m/s to 5.0E-4 m/s and in Reach 6, HC decreased from 7.70E-04 m/s before remediations to 5.6E-04 m/s after remediation actions. All the measurements have uncertainties, especially since homogeneity is assumed to some extent and the natural environment will always be heterogeneous.

  • Zeidler, Jacob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Conceptual Design Study of a Foil-Trailer to AUV 62-AT2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish Navy has been using the AUV62-AT for submarine hunting training successfully for a while and it has been found that the biggest drawback is the transport which is very resource draining. The Swedish Defence Materiel Administration was given the task to solve this and a hydrofoiling-trailer was seen as a potential solution. This thesis will present the design process of the foil-trailer as well as issues found and how theses were mitigated, to produce a viable design. To develop the final design both current use of hydrofoil vessels and further adaptions needed for this applications were investigated. The project was done in collaboration with Simon Källerfelt Korall, who has during the project investigated in detail the foil-trailer’s roll stability, presents this in "The development of a foiling trailer for transport of the AUV62-AT"[1], which deals with how the experimental- and model results lines up. The result is a final design of a foil-trailer which is constituted of several sub-systems that has been found to improve the overall concept. It was concluded that the concept was viable and if further developed it can be used as a great method of saving time when deploying the AUV62-AT.

  • Dettmann, Aaron
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Loosely coupled, modular framework for linear static aeroelastic analyses2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A computational framework for linear static aeroelastic analyses is presented. The overall aeroelasticity model is applicable to conceptual aircraft design studies and other low-fidelity aero-structural analyses. A partitioned approach is used, i. e. separate solvers for aerodynamics and structure analyses are coupled in a suitable way, together forming a model for aeroelastic simulations. Aerodynamics are modelled using the vortexlattice method (VLM), a simple computational fluid dynamics (CFD) model based on potential flow. The structure is represented by a three-dimensional (3D) Euler-Bernoulli beam model in a finite element method (FEM) formulation. A particular focus was put on the modularity and loose coupling of aforementioned models. The core of the aeroelastic framework was abstracted, such that it does not depend on any specific details of the underlying aerodynamics and structure modules. The final aeroelasticity model constitutes independent software tools for the VLM and the beam FEM, as well as a framework enabling the aeroelastic coupling. These different tools have been developed as part of this thesis work. A wind tunnel experiment with a simple wing model is presented as a validation test case. An aero-structural analysis of a fully elastic unmanned aerial vehicle (UAV) (OptiMale) is described and results are compared with an existing higherfidelity study.

  • Ankarsköld-Flück, Kevin
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Wiskman, Erik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Development of a motion platform for the G1X radar2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Giraffe 1X is a mobile short range 3D radar from Saab used for example to detect threats and create protection in a ground based air defence system. It can also be used on naval platforms for air and surface surveillance. During the development of the radar, the system needs to be tested for both sea and mobile land applications. The most convenient place for testing is on the roof of Saab’s facility in Gothenburg. There elevators can raise the radar to the roof giving an excellent view of for example Landvetter airport and the sea. To aid future verification experiments of the radar system, this project was started in order to develop and construct a motion platform used to simulate sea- and vehicle motions. During a six month period at Saab, the work of the project was started with a thorough research of motions platforms to conduct preliminary concept studies. Furthermore the concepts were drawn as 3D-CAD models in Creo Parametric in order to visualise the different solutions and present them for suppliers. The report also covers the assembly of the produced parts, together with the development of a user interface to control the motion platform.

    Lastly, the result of product development is a two-degree of freedom (DOF) motion platform influenced by the gyroscopic gimbal concept. The G1X radar is mounted on a gimbal platform which is made out of two aluminium frames, whereas the outer frame rotates around an horizontal axis while the inner frame rotates around a transversely mounted horizontal axis mounted on the outer frame. Each aluminium frame is attached to a link arm which is mounted on a motor that is used to tilt the frame. The platform can be tilted _ 22 o in pitch and _ 22 o in roll. The gimbal is supported by a steel structure to allow ground clearance and to raise the radar to a comfortable working height.

  • Busseti, Gabriele
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Modal and Fatigue Analysis of the Stratotimer2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fatigue analysis of the printed circuit boards (PCBs) of an avionic instrument has been analyzed. The natural frequency and transmissibility has been estimated through analytical approach and finite element approach with Solid- Works and experimentally. Fatigue analysis damage has been obtained with three methods: Steinberg Stress approach, Steinberg Relative Displacement approach and Dirlik method. The analysis indicates that the solder that holds the CPU on the control unit is critical for the fatigue life. The results show that each method is far from the critical CDI value of 0:7 and therefore the design could be optimized.

  • Wehtje, Ernst
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Development of miniaturized fill and drain system for propellant tanks on small satellites2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During recent years, private funding and new technology have boosted a change of the space industry, resulting in smaller and cheaper satellites being available on the market. GomSpace Sweden, part of GomSpace Group, is located in this market and develops propulsion systems for small satellites, so called, CubeSats. One of these highly miniaturized and efficient products is the cold gas propulsion system, suitable for 3-unit CubeSats. Due to the current design, the propellant tank of the system can be filled through a port but only drained through the thrusters, which causes several issues. This thesis concerns the development of a solution to these issues and creating a complete fill and drain system.

    A conceptual solution for a fill and drain tool was created and later designed as well as manufactured. The tool was tested and all initial requirements were successfully verified. However, through testing the functionality of the tool, several areas of improvement were found. A second version of the tool was digitally designed to meet these improvements. Also, a proposal of a more general fill and drain solution was digitally designed, which could be realized as a module in future development processes, including a fill and drain tank interface, fill and drain tool and a fill and drain procedure.

    In conclusion of the thesis, a solution to the problem with the current design of the propulsion system was successfully developed and tested. An improved version of the solution was designed, which decreases the risk of damage to the propulsion system and simplifies the usage. Finally, a design of a general fill and drain system was created, which could possibly span over several future GomSpace products and lowering both the cost and time of development.

  • Söderlund, Johanna
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    A study of risk management for serie produced vessels, in relation to the IMO risk perspective2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The International Maritime Organization, IMO, aims to at a larger extent build their work in relation to and around risk management. It is therefore here investigated how IMO standards comply with industry risk management processes. The IMO risk perspective used in this study is the Formal Safety Assessment, FSA. The FSA was created to evaluate and compare new regulations in regards to cost and administrative or legislative burden and is a risk management methodology, which goal is to improve maritime safety. The FSA uses risk analysis and cost benefit assessment, and covers both technical and operational issues.

    By comparing the IMO risk perspective with industry risk management processes, and analysing the practical use of the FSA by applying it to three maritime accidents the goal with this report is to find similarities and differences of the two perspectives and present possible carryovers from industry risk approaches to the IMO risk perspective.

    It was found that the IMO risk perspective, here represented by the FSA, does overall comply with industry risk management processes. The main difference is that general industry risk management processes focuses on all phases of the development and use of a vessel, from the concept phase to the operation phase but the FSA focuses mainly on the operative perspective of the design phase and the operation phase. The largest deficiency of the FSA is the non-existing demands on safety culture which is found to be a requirement when doing a successful risk management assessment. If IMO is considering the FSA as their main risk management method to be used, it is important that requirements on safety management is added.

  • Miao, Tianlei
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Generation of a full-envelope hydrodynamic database for hydrobatic AUVs: Combining numerical, semi-empirical methods to calculate AUV hydrodynamic coefficients2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The next generation of Autonomous Underwater Vehicles (AUV) can impact our observation of the world. The flight simulation and full-envelope hydrodynamics modeling can improve the performance of AUVs in terms of control, navigation and positioning. In order to achieve agile maneuverability, a more accurate database of full-envelope hydrodynamic coefficients is supposed to be generated.

    Two semi-empirical methods, Jorgensen and DATCOM, and two numerical method, Computational Fluid Dynamics (CFD) and XFLR5 are used to push the boundaries of hydrodynamic coefficients: lift, drag and moment coefficients for flight-style AUVs at the Swedish Maritime Robotics Center (SMaRC). A comparison of different approaches and tools, and an analysis of the most appropriate approaches for different regions of a defined maneuver has been conducted in this thesis. A data confidence level was proposed as a way to estimate the accuracy of the data and a structured database was built in terms of data confidence level. Different components of the AUV such as the hull body and wings were analyzed separately. The new database is input to a 3DOF Simulink model and the 6DOF SMaRC hydrobatics simulator for flight dynamics simulations. Simulations show that the new database has a good applicability.

  • Cirillo, Giovanni
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Space Surveillance and Tracking Tool: Implementation and Test of New Methods​2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In March 2019 the number of artificial objects bigger than 1 mm in orbit around the Earth is estimated to be more than 170 millions. Only a small fraction of them (0.03%) is catalogued. An impact of an operational satellite with one of these debris can damage the satellite and undermine its mission. So it is important to catalogue as many objects as possible in order to reduce the risk of a collisions. This is done by using the software tool Space Object Observations and Kalman Filtering (SPOOK), developed in Airbus Defence and Space in Friedrichshafen. The goal of this Master Thesis was to create newfunctionalities to this tool and improve the existing ones. In particular three main goals have been accomplished:

    • a new model for the lighting ratio has been built to take into account the occultation of the Sun due to a covering body (for example the Earth or the Moon) and itsinfluence on the solar radiation pressure, necessary to have a good model for orbit propagation;

    • a tracklet building algorithm has been built to distinguish different tracklets (consecutive observations of the same object along its orbit) as a starting point for the association of different measurements belonging to the same object at distant epochs, necessary to update a catalogue of space objects;

    • a model to take into account the process noise has been improved giving some suggestion on how to tune the different parameters for different kinds of orbit.

     

  • Chan, Charlotte
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Compaction Simulation for Prepreg-AutoclaveManufacturing: Improvements and Simplifications of Two Compaction Simulation Methodologies2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a competitive market such as the aerospace industry, the use of manufacturing process simulation is vital to decrease time and cost of tooling and process development. In the autoclave process, to obtain an uniform part with no void, it is crucial to understand the compaction phenomenon. Through the last decades, compaction simulation methodologies have been developed but only rather simple geometry and/or small parts have been studied. At Airbus Helicopters Deutschland, compaction simulation methodology needs to be able to predict outcomes of rather large and complex helicopter parts such as the final thickness, porosity, wrinkles, thickness deviation, etc. In the two existing Airbus Helicopters Deutschland simulation methodologies, the main problems are the complexity of the simulation process, high computational costs and substantial set-up for rather simple parts. The research presented in this Master thesis aims at providing improvements and optimisations of the two simulations. A comparison of the two methods is also performed in terms of applicability, accuracy, set-up time and computational cost to assess which method should be favoured depending on the problem. Samples previously built at Airbus or during this thesis are used for the simulations’ calibration and validation.

    For the first method based on the soil approach, parameters such as the autoclave cycle length, the shear stiffness of the fibres, pore pressure boundary condition, number of contacts, mesh size and radius discretisation are investigated. This method is capable of predicting’ accurately the final thickness and the thickness distribution behaviour for flat and curved parts. However, at lower consolidation pressures, the accuracy decreases. Furthermore, this simulation methodology requires high computational and set-up times. During the calibration of the method, CPU and setup times are reduced by using smaller model and coarser mesh while still achieving a correct result.

    For the second methodology based on membrane elements while neglecting flow effects, the contact modelling is calibrated: the contact stiffness is correctly altered to fit the thickness variation during the manufacturing process. Calibration is done for flat parts. However, wrinkles start to form in the curved part model where no such defect was observed in the samples. This issue needs to be investigated first to continue the simulation calibration. The method shows accurate results for each pressure cycle with lower computational cost and faster set-up than the first method.

    In addition, wrinkles can be visualized directly in the simulation and core material such as honeycomb and foam sandwich cores can be taken into account. This method looks quite promising but needs further investigation.

  • Berhouni, Ilyès
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Flow transition prediction approaches evaluated on a single-aisle type aircraft2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, as the demand for fuel efficiency is increasing and the manufacturing techniques improved to allow the design of laminar wings, the laminar concepts are being revived and studied, and seen as one of the most promising techniques to reduce skin friction and hence the overall drag of the airframe. In order to predict the kind of benefits that could be obtained from such concepts, computational fluid dynamics (CFD) computations can now be carried out but it is necessary to be able to predict flow transition from laminar to turbulent around the lifting surfaces of the aircraft, such as the wing and the horizontal tail plane. Such capability has been developed in the last years by the French Aerospace Laboratory (ONERA) with their CFD code elsA, and by the German Aerospace Center (DLR) with their CFD code Tau. These two codes are widely used in Airbus in their CFD campaigns, and this study aims to assess the capability of the different approaches to predict transition and the benefits from laminar flow in the overall drag. The methods used, the limitations and the suggestions for further improvement of the codes will be detailed in this paper.

  • Charpigny, Noé
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    An Executable System Model for Behavioural Analyses of the LISA Mission2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis report presents the modelling process of key elements of the Laser Interferometer Space Antenna mission (LISA mission) in a Modelbased systems engineering (MBSE) approach with SysML (Systems Modeling Language). The model implements a selected set of functions of the mission through executable graphical representations, called diagrams. It is shown how such diagrams can benefit the mission, by comparing this mean of information exchange to the traditional text- based systems engineering. The model represents the mission structure and behaviour through a system of nested layers. The deeper the layer is, the more it gives details on a system part. Each layer can be seen from different point of views, either focusing on the structure, the behaviour, or the performance of related system part.

  • Abrahamsson, Erik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    En övergripande studie av undervattensdockning med obemannade farkoster i ubåt A262019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, a Systems Engineering work is discussed, where an investigation has been carried out on the possibility of docking an autonomous underwater vessel with the new generation submarine A26. In the work, the focus has been on the early steps of the Systems Engineering discipline. A literature review of existing research and work in the field has been carried out in order to identify

    possible technical solutions accessible today. Stakeholders have been identified and people with key positions in each area have been interviewed to be able to compile the requirement of needs. Based on the needs, abilities that the system needs to meet have been mapped. In order to facilitate the analysis of the docking system, a definition as well as a zoning of the various stages of the docking process have been performed. A description of different technologies for underwater communication is shown and discussed. An evaluation and risk analysis of a docking system has been carried out to illustrate the pros and cons of the various communication technologies during a docking procedure. Finally, two mechanical systems for the final phase of a docking have been compared to each other.

  • Public defence: 2019-11-07 13:00 F3, Stockholm
    Åsberg, Per
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Brand Architecture from Above: Understanding the Customer Disconnect2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Global business is transforming. Information technology in general, and the Internet specifically, has globalized business and empowered the consumer with more information and choice than ever before. Consequently, academic research into brand portfolios and brand architecture is faced with new challenges to reflect this changing reality.

    Traditional research into brand portfolio management and its structural embodiment using brand architecture has approached these concepts from the perceptive of the brand owner/company. For instance, the portfolio has been mapped based on legal ownership of brands, which has been criticized as being a too narrow approach that exclude key contributors of the portfolio’s collective brand equity. Even in the cases where partner brands are acknowledged as part of the portfolio, their inclusion is often based on the revenue stream they represent or their link in the distribution chain instead of association. Brand architecture research has therefor focused on structural representations based on hierarchical trees created within the walls of the company itself, without necessarily investigating if the intended structure works as expected.

    The missing ingredient in this halting logic is the perceptions of the market in which the portfolio and its architecture operates. Associations and transfer of brand equity is dependent on a concept’s mental perception in the minds of consumers. An endorsement that does not get noticed by the target market is a mirage in the minds of marketing managers, and an historical collaboration that was cancelled years ago may still influence the brand portfolio today by means of association in consumer memory.

    The research presented in this thesis extends current theory in brand portfolio management and brand architecture to directly include the consumer perspective. This thesis re-classifies the portfolio and architecture concept as perceptual constructs whose efficiency is determined by the mental alignment between company representatives as the creators of the intended meaning and customers as the interpreters, or even co-creators, of the same. Study results presented indicate significant misalignment not only between stakeholder groups as a collective, but also between individuals within each group – even for brand managers working together on the same portfolio day after day. Current hierarchical models for representing brand architecture are extended using the perceptual dimension as well as a layer accounting for the openness of the portfolio, and a new brand portfolio model segregating brands based on the degree of perceptual inclusion in the portfolio is presented.

    This introduction of the perceptual dimension into both brand portfolio management and brand architecture represents a new way to view these abstract concepts, a conceptual idea that has ripple effects into areas such as brand equity transfer, brand alliances, and portfolio risk management.

  • Liu, Lida
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Hardware-Efficient WDM/SDM Network: Smart Resource Allocation with SDN Controller2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optical networking has been developing for decades and wavelength-division multiplexing (WDM) is the main technology used to carry signals in fiber-optical communication systems. However, its development has slowed because it is approaching the Shannon limit of nonlinear fiber transmission. Researchers are looking for multi dimensional multiplexing. Space-division multiplexing (SDM) is an ideal way to scale network capacities. The capacity of WDM/SDM network could be expanded to several times the capacity of WDM network but the active hardware devices may also increase by several times.

    This project aims to answer a practical question: How to construct a WDM/SDM network with less hardware resource? There is no mature research about WDM/SDM network yet. Therefore, the problem can be divided into two parts: (1) how to build a WDM/SDM network and (2) how to allocate resource and compute routes in such a network to minimize hardware resources.

    First, this thesis proposes a WDM/SDM node which has bypass connections between different fibers and architecture on demand (AoD) to effectively decrease the number of active hardware devices within the node. Then, two types of networks were constructed: one with bypass connections in each node and another one without any bypass connections. These networks were under the control of a software defined network (SDN) controller. The controller knew the wavelength resources within the networks. Several algorithms were applied to these networks to evaluate the effect of a bypass network and to identify the desired characteristics (to find short length path and decrease the probability of spectrum fragmentation) of an algorithm suitable for a network with bypass connections. The results of applying the proposed algorithms in two networks proved that the bypass connections increased the blocking probability in small topology but did not affect the results in large topology. The results in a large-scale network with bypass network were almost the same as the results in a network without bypass connections. Thus, bypass connections are suitable for large-scale network.

  • Miri, Majid
    et al.
    Ashtari, Elmira
    KTH.
    The Applicability of a Newly Developed Revit Add-in for Architects and Urban Designers When Doing Daylight Study from Early Stages to the End of Architectural/Urban Design2019Conference paper (Refereed)
    Abstract [en]

    Including daylighting strategies from early to the end in the building and urban design process is crucial when it comes to the compliance of environmental certification systems or when the aim is to simply create an interior or exterior space with sufficient access to natural light while still thermally comfortable. Therefore, in this paper, we are going to introduce and discuss a new tool that is an add-in for Autodesk Revit and newly developed by the authors to help architects or urban designers/planners to evaluate daylight condition of exterior or interior spaces by calculating different daylight metrics in different design stages. Since, in a BIM model, most of the information that is needed for daylight analysis are already included in the model, lots of time and human errors can be reduced, if there is a possibility to make direct communication between the BIM model and Radiance that is a physically valid lighting and daylighting simulation software and works as the main calculation core for doing different types of daylight simulations in this add-in. Thus, by saving time and minimizing the mistakes and associated problems when exporting the model for analysis directly from Revit to Radiance and importing the results vice versa, this new add-in makes its users free from using any other third- party software. All in all, the main goal of this add-in is to work as a supportive decision-making tool for those dealing with indoor or outdoor quantity and quality of daylight and its associate threats during architectural design process. Moreover, its results can be used for other assessments such as when doing a thermal comfort analyses or electrical energy consumption in a building. Therefore, it can be helpful for architects, urban designers/planners, and engineers in their everyday works.

  • Waldau, Leonard
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Development of an aquatic UAV capable of vertical takeoff from water2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report presents a master’s thesis edition involving the Maribot Petrel project, which concerns the development of a long range aquatic UAV capable of vertical takeoff from water in order to hop between different locations and to perform measurements in archipelago conditions. A concept evaluation phase was performed where multiple aquatic UAV ideas were investigated. This phase led to the conclusion that a flying wing with nose-tilting engine was the best concept to further invest in. Further, two prototypes of different sizes were then constructed and tested with positive results. The concept proved to be a promising platform for further development of the project.

  • Pavlovic, Boban
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Dynamic Performance Analysis of a Fighter Jet with Nonlinear Dynamic Inversion2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A modern view of aircraft performance analysis, is to quantify aircraft manoeuvrability with agility metrics. There are several different agility metrics, which can be seen as indexing of the aircraft agility performance. The quantified unit is the time it takes for the aircraft to perform a specific manoeuvre relevant to a given agility metric. In this thesis, estimations are done of two agility metrics, the CCT (Combat Cycle Time) and the T90 (Time to capture 90◦ bank angle) for the F-18 HARV aircraft.Estimations of the agility metrics were obtained by simulating a six-degree-of-freedom aircraft model of the F-18 HARV aircraft performing the specific manoeuvres. To control the aircraft model during the simulation a control sys-tem was developed based on the NDI (Nonlinear Dynamic Inversion) method with time scale separation assumption. The method uses the feedback from the controlsystem for linearizing the aircraft system, which results in that simple linear controllers can be applied to the nonlinear aircraft model.In this case simple proportional controllers were implemented and in the case of estimating the T90 agility metric additional gain scheduling as functions of altitude and Mach number was required to extract maximum performance. Although the control system was developed for these two specific agility metrics, results indicates that the NDI method provides an effective way to implement controllers for complex systems, especially when considering a high nonlinear flight regime.

  • Ekman, Fanny
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Operationalizing the SDGs in a Systems Engineering Framework for ship design concept studies2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sustainable transport involves more choices and possibilities than ever before, and the topic is widely discussed within the maritime industry.

    To a large extent the innovations and technology exists, but even though there is a drive and consciousness to change, sustainability is still not a cornerstone in the decision-making process when new ships and transport solutions are developed. The gap between sustainability ambitions and actual actions is far from closed.

    This thesis introduces a new framework called Systems Engineering for Sustainable Ship design (SE4SS), which is based on the Systems Engineering methodology for conducting concept developments and the Sustainable Development Goals (SDG) for operationalizing sustainability.

    The new framework makes sustainability aspects an essential part of ship design concept development and the following decision-making process.

    The SE4SS framework includes an application of the SDGs on a product level (ship) and suggests appropriate tools & methods for sustainability assessment, considering different levels of ambitions and amount of available resources that projects may have.

    The framework has been validated against three cases of ship design concept development within the commissioner organization SSPA. The result shows that the suggested approach is useful in terms of ; (1) raising a holistic awareness of sustainability aspects in ship design, highlighting the existing opportunities and responsibilities, (2) creating a more transparent trade-off analysis where priorities need to be stated, preventing greenwashing, (3) structuring the process which facilitates the integration of sustainability aspects from the start and the communication between the project manager/naval architect and different stakeholders. Full-scale application of the SE4SS is needed in order to fully validate its usability and generalizability, however this thesis argues that the introduced framework may be a valuable tool in both illuminating and reducing the ambition-action gap within the maritime sector.

  • Díaz Vázquez, Guillermo
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Case Data Analysis Tool for PowerFLOW2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The field of computational fluid dynamics (CFD) is exponentially growing in terms of performance, robustness, and applications. The expansion of CFD also means more users and more simulations, which translates into more human errors and mistakes in the simulation set up. Because the simulation set up should be the correct in order to accurately reproduce the desired phenomenon, such errors must be mitigated in order to increase the reliability and robustness of the simulations. In this project a tool has been developed to tackle this issue, within the CFD software SIMULIA PowerFLOW. The tool extracts and analyzes the data of the cases before simulation, reporting the results to the user for error detection. The present work aims to present the implementation, the application and the benefits of the designed tool.

  • Chea, Ming Kai
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Investigating In-plane Shear Behaviour of Uncured Unidirectional Prepreg Tapes2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Steering of prepreg tows in an automated fibre placement (AFP) process allows geodesic layup trajectory over a doubly-curved surface, as well as the potential to improve the efficiency of composite structures by tailoring their stiffness. However, defects (such as out-of-plane buckling and tow pull off) are commonly generated when the steering radius exceeds a critical limit, which impact the mechanical properties of the finished product.

    The in- and out-of-plane material properties of the prepreg tows have been shown to significantly influence the quality of the layup. In this thesis, in-plane shear behaviour of uncured IMA-M21 unidirectional (UD) prepreg was characterised using an off-axis tensile test to derive material parameters for process models to predict steering limits and defects.

    Test parameters, such as shear strain rates and temperatures, that were investigated were consistent to the actual AFP process. The results demonstrates the expected strain-rate and temperature dependencies related to the resins viscoelastic behaviour. Subsequently, a novel micro-mechanical finite element (FE) simulation of a 3-dimensional UD prepreg unit cell in pure shear was conducted to gain qualitative insights into the complex rheological behaviour at play. It effectively demonstrates how fibre friction, resin viscosity and shear strain rates influence the load transfer between fibres and melt, as well as the movement of fibres during the shearing process. These were reflected in the shear stress-strain curves generated in the simulation and elastic micro-buckling observed in the fibre elements. The results pave a way for future development of a robust material model for predicting the critical process parameters to achieve quality layups from AFP steering process.

  • Källgren, Tom
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Nordling, Olof
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Community Supported Agriculture” i Sverige: Modellens bidrag till ett hållbart livsmedelssystem2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Around the world there are many models, goals and visions for sustainable development, and many of these can be linked to agriculture. Food is vital for humans and thus food production is one of the most important industries we have. It is also the source of a large part of emissions, fresh water use, eutrophication and other problems concerning the environment, economy, living conditions and much more. Thus, to ensure sustainable development for society as a whole, sustainable food systems are an important piece of the puzzle, but the development over the past hundred years has gone towards an intensification, globalization and mechanization of agriculture like never before.

    As a response to this, several alternative food systems have been developed with different scales, starting points and results. One of these systems is the concept of Community Supported Agriculture (CSA) (Swe. Andelsjordbruk). The concept was developed in the 1960s in Europe and Japan and came to the USA in the 80s where since then the number of CSA-farms has increased to thousands, but in Sweden it is still relatively new and the knowledge about this form of cooperative agriculture is small. Most of the 50 or so CSA farms in the country have started in recent years and for consumers, legislators, and farmers, the research that has been done in other countries has yet to be done in Sweden in order to allow them to make decisions and open up for further development of the concept.

    This work aims to highlight the ways in which the CSA model can contribute to sustainable development. This is done by conducting a literature study of the model and sustainable food systems in general and then linking the results to the set goals for sustainable development that exist at global, national and local level. Aswell as comparing to a case study reference, a CSA-farm in Södertälje called Under Tallarna. The results indicate that CSA has much to contribute in several aspects of sustainable development. In addition to sustainable production of food, there are benefits, for example, in health, economy, development of rural areas, local communities, and culture. Achieving the set sustainability goals requires a transformation of the current food system and the conventional agriculture at its core. The result of the study shows that the CSA concept, with the support of stakeholders throughout the food system, has the potential to facilitate such a transition.

  • Tegbrant, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Cost-effectiveness of ergonomic interventions - Evaluation of a calculation model2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Several studies have shown that the work environment affects company performance. The managers are seldom aware to which extent work environment problems affect productivity, quality of delivery and sick-leave in their organisation. The present literature study showed that improvements regarding physical ergonomics generally are shown to be cost-effective. The most beneficial way of working is through proactive measures interactively with employees. An efficient, systematic way of performing risk assessments and interventions reduce the need for a calculation method. This study identified propositions for properties of calculation methods. These propositions were : “Simplicity, high usability”, “Right content for the target group”, “High ability to measure risk”, “Focus on staff”, “Correct standardised values”, “Right focus” and “Optimal design”. Scania CV, a producer of trucks and buses, has developed a calculation model for cost-effectiveness of ergonomic interventions. Evaluation of this model with semi-structured interviews showed agreement regarding the need of a simplified calculation method, based on systematic risk assessments.

  • Zec, Kenan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Hansson, Sofia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Home Care Logistics: A Monitoring System with a Communication Unit for the Elderly2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Humans are growing older which presents challenges for the health care system. One solution for allowing individuals to continue living in their home, despite age related dif- ficulties, is a sensor based surveillance system. These systems can monitor a number of parameters, for example motion or temperature. If certain limits are exceeded the sys- tem can notify family members or health care services. The aim of this project was to build a prototype of such a system which also had to be cheap and easy to install and maintain. The final prototype consists of a motion detection sensor in the bathroom, a temperature sensor around the kitchen stove and a temperature sensor for measurement of ambient room temperature. Each sensor is connected to its own Arduino and they are all programmed with different limits. The sensors communicate wirelessly with a central hub through the communication protocol LoRa. Once the central hub, which consists of a Raspberry Pi, receives a LoRa signal it sends an email to a chosen address.

  • Storfeldt, Joakim
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Design benefits with Additive Manufacturingfrom a convective heat transfer perspective2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays manufacturing processes are rapidly developing. Salt-bath dip brazing is a conventional manufacturing method commonly used by Saab AB to fuse aluminium components in a high temperature salt bath. However conventional manufacturing methods have shown some limitations. Additive Manufacturing, or 3D printing, is a newer technology which has become very popular in the industry offering competitive advantages regarding production time and size, and structural complexity of the components among other aspects. In this work, Additive Manufacturing is investigated to assess if the performance of heat sinks can be increased compared to the salt-bath dip brazing method.

    Geometrical shapes of heat sink-fins were studied by empirical research to compare their characteristics in air-flow, convection and pressure drop. Eight different geometrical shapes have been analyzed using Additive Manufacturing, and the control plate fins was used as a reference for comparison with salt-bath dip brazing. It was found out that the NACA 0010 fins and Square Grid fins geometries gave the best performance with a 63% and 64% decrease in pressure drop per diverted energy compared to the control plate fins, respectively.

  • Public defence: 2019-11-06 10:00 Kollegiesalen, Stockholm
    Song, Meng
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Planning and Operation of Demand-Side Flexibility2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Power systems are changing with growing penetration of non-dispatchable renewable generation and increased demand of electric energy. More generation, transmission or distribution capacities are needed to balance the varying production and higher consumption. Demand-side flexibility is a potential solutionto tackle those challenges. By shifting the consumption time and temporarily increase or decrease the power demand, the demand-side flexibility can help to integrate more wind and solar energy in the system, alleviate network congestion and postpone the investment for grid reinforcement. Therefore, technical and regulatory measures are undergoing in many countries to encourage demand response and engage customers.

    On the other hand, unlocking the flexibility will introduce more complexityand uncertainty on demand side. This would result in difficulties for different actors in power systems and power markets to make optimal decisionsin their planning and operation. The thesis addresses the problem by proposing methods to support the decision making of actors on demand side. Firstly, it develops models to facilitate residential customers and commercial electric vehicle fleet operators scheduling their shiftable appliances for reducing electricity cost. The willingness of households for responding to time-varying price is taken into account. Results from Stockholm Royal Seaport project are analysed to demonstrate such willingness. Secondly, the thesis develops models for the short-term planning of retailers and balance responsible players. Different approaches are deployed under price-taker and price-maker assumptions respectively. The planning concerns the price sensitivityof end customers and the risk related with certain bidding strategies.Thirdly, the thesis proposes models to coordinate and aggregate the flexible charging power of electric vehicles to provide regulation service on the balancing market. The models encompass the decision process from day-aheadplanning to real-time operation management. The proposed models in the thesis are based on the rules of Nordic electricity market and could be further developed for adapting to other market frameworks. Stochastic programmingis applied to address the uncertainties about consumption and market behaviours.In addition, the thesis discusses the impacts of demand response interms of generation cost, system reliability and market price. It shows that a widely implemented demand response can reduce the total generation cost, improve the reliability of supply and decrease the market price.

  • Public defence: 2019-12-03 10:00 Kollegiesalen, Stockholm
    Ahmed, Laeeq
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Scalable Analysis of Large Datasets in Life Sciences2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    We are experiencing a deluge of data in all fields of scientific and business research, particularly in the life sciences, due to the development of better instrumentation and the rapid advancements that have occurred in information technology in recent times. There are major challenges when it comes to handling such large amounts of data. These range from the practicalities of managing these large volumes of data, to understanding the meaning and practical implications of the data.

    In this thesis, I present parallel methods to efficiently manage, process, analyse and visualize large sets of data from several life sciences fields at a rapid rate, while building and utilizing various machine learning techniques in a novel way. Most of the work is centred on applying the latest Big Data Analytics frameworks for creating efficient virtual screening strategies while working with large datasets. Virtual screening is a method in cheminformatics used for Drug discovery by searching large libraries of molecule structures. I also present a method for the analysis of large Electroencephalography data in real time. Electroencephalography is one of the main techniques used to measure the brain electrical activity.

    First, I evaluate the suitability of Spark, a parallel framework for large datasets, for performing parallel ligand-based virtual screening. As a case study, I classify molecular library using prebuilt classification models to filter out the active molecules. I also demonstrate a strategy to create cloud-ready pipelines for structure-based virtual screening. The major advantages of this strategy are increased productivity and high throughput. In this work, I show that Spark can be applied to virtual screening, and that it is, in general, an appropriate solution for large-scale parallel pipelining. Moreover, I illustrate how Big Data analytics are valuable in working with life sciences datasets.

    Secondly, I present a method to further reduce the overall time of the structured-based virtual screening strategy using machine learning and a conformal-prediction-based iterative modelling strategy. The idea is to only dock those molecules that have a better than average chance of being an inhibitor when searching for molecules that could potentially be used as drugs. Using machine learning models from this work, I built a web service to predict the target profile of multiple compounds against ready-made models for a list of targets where 3D structures are available. These target predictions can be used to understand off-target effects, for example in the early stages of drug discovery projects.

    Thirdly, I present a method to detect seizures in long term Electroencephalography readings - this method works in real time taking the ongoing readings in as live data streams. The method involves tackling the challenges of real-time decision-making, storing large datasets in memory and updating the prediction model with newly produced data at a rapid rate. The resulting algorithm not only classifies seizures in real time, it also learns the threshold in real time. I also present a new feature "top-k amplitude measure" for classifying which parts of the data correspond to seizures. Furthermore, this feature helps to reduce the amount of data that needs to be processed in the subsequent steps.

  • Putra, Ramadhani Pamapta
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Implementation and Evaluation of WebAssembly Modules on Embedded System-based Basic Biomedical Sensors2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    WebAssembly is a new binary code specification, which was initially designed to complement JavaScript in web applications. WebAssembly is inherently portable and small, designed for multiplatform usage. Therefore, WebAssembly modules can be created to support embedded system-based biomedical sensor operation. However, WebAssembly has its own limitations to compensate with its portability. In this thesis, we show how WebAssembly modules can be applied to the basic biomedical modalities of body temperature, heart rate, and breathing pattern.  We show how the implementation performed, and what challenges were met during the development. It is concluded that WebAssembly can be applied for achieving safe and effective biomedical sensor devices, although with some limitations.

  • Rahgozar, Parastu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Evaluation of a Radiomics Model for Classification of Lung Nodules2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lung cancer has been a major cause of death among types of cancers in the world. In the early stages, lung nodules can be detected by the aid of imaging modalities such as Computed Tomography (CT). In this stage, radiologists look for irregular rounded-shaped nodules in the lung which are normally less than 3 centimeters in diameter. Recent advancements in image analysis have proven that images contain more information than regular parameters such as intensity, histogram and morphological details. Therefore, in this project we have focused on extracting quantitative, hand-crafted features from nearly 1400 lung CT images to train a variety of classifiers based on them. In the first experiment, in total 424 Radiomics features per image has been used to train classifiers such as: Random Forest (RF), Support Vector Machine (SVM), Decision Tree (DT), Naive Bayes (NB), Linear Discriminant Analysis (LDA) and Multi-Layer Perceptron (MLP). In the second experiment, we evaluate each feature category separately with our classifiers. The third experiment includes wrapper feature selection methods (Forward/Backward/Recursive) and filter-based feature selection methods (Fisher score, Gini Index and Mutual information). They have been implemented to find the most relevant feature set in model construction. Performance of each learning method has been evaluated by accuracy score, wherewe achieved the highest accuracy of 78% with Random Forest classifier (74% in 5-fold average) and 0.82 Area Under the Receiver Operating Characteristics (AUROC) curve. After RF, NB and MLP showed the best average accuracy of 71.4% and 71% respectively.

  • Nicolle, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    Mechanical and structural conceptof the ISS microgravity experimentpayload: AtmoFlow2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master Thesis report presents the mechanical concept and design of a microgravity fluid science experiment that is planned to be launched to the International Space Station in approximately five years. Named AtmoFlow, this experiment aims to study the complex flow phenomena occurring in different planets’ atmosphere by implementing a scaled-down model of a planet-atmosphere system in microgravity. The design introduced here focuses on several of the experiment’s systems: the Turn Table, a rotating system involving a Fluid Cell Assembly, a Thermal Control System and two Rotation Drive Systems. Design methods, main choices and crucial conception steps are presented. Components’ dimensioning and choices are motivated. Models and analyses are derived from the selected design to ensure that the design meets the requirements on microgravity disturbances, structural and rotational characteristics stated during previous project’s phases. The Computer Assisted Design model of the experiment’s final concept and its integration sequence are eventually proposed and discussed.

  • Wanner, Svenja
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Systematic approach on conducting fatigue testing of unidirectional continuous carbon fibre composites2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High fuel saving potentials, increased load carrying capacities and therefore competitive advantages force the heavy goods vehicle industry to enhance the efforts towards comprehensive lightweight designs. Facing this challenge, the material evaluation in terms of simulations and physical testing of composite materials is required for the design against fatigue failure due to road introduced vibrations. Eliminating fatigue testing issues in order to gain acceptable and reproducible results, a future-oriented systematic approach on conducting constant amplitude tension-tension fatigue testing on a unidirectional composite material is presented. Following the material characterisation of the carbon/epoxy material in terms of tensile and shear properties as well as fibre volume fraction, several combinations of tab configurations and specimen geometries have been tested with regard to their suitability for fatigue testing. Finally, the unidirectional material was successfully tested under tension-tension fatigue and first elaborated test data were assessed. In conclusion, the usage of straight aluminium tabs completely clamped inside the grips and bonded to the straight-sided specimen with 3M DP420 adhesive, using ventilation during the test is the recommended test procedure.

  • Shwan Kurdi, Mir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Nonlinear Attitude Control ofa Generic Aircraft2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Determining suitable controllers for the process of evaluating dynamic per-formance of multiple versions of an aircraft’s aerodynamical, geometric and propulsive properties in its conceptual stage is an expensive task.In this report a proposition is made to utilize a generalized feedback lin-earizing controller that o˙ers the aircraft designer valuable insight into the manoeuvre performance of their aircraft. This is carried out by first estab-lishing fundamental requirements for a controller capable of treating a generic airframe, and formulating the resulting control laws.It is shown in this report, that with a suÿciently simple aerodynamic and propulsive model explicit feedback linearization is possible with satisfactory performance and robustness. Whereas it would be necessary to implement INDI if explicit inverse mappings are not obtainable. Which in turn would introduce additional tuning parameters.Robustness verification is performed in two stages, firstly by introducing a high model uncertainty within the flight control system and showing, via simulation, that the control system successfully performs desired multi-axial manoeuvres whilst managing to maintain the induced side slip below 0.1◦. Secondly by disturbing the aircraft with a discrete side slip. Critical side slip disturbance angle was found to be considerably larger than that for regular aircraft entailing that the used case study may be somewhat over dimensioned with respect to yaw control authority.

  • Philippe, Alexis
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Optimisation of an aeronautic production line through the managementof tools and the shortage of items2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is part of a process to ensure the production ramp-up of the A320neo aircraft pylons at Airbus Saint-Eloi factory (Toulouse). The aim of the project was to optimise the production management in order to sustain the transition to a serial production of the assembly lines. The objective of the thesis work was to develop a model to prevent the downtime of the production lines caused by the shortage of the assembly lines or the unavailability of tools on workstations.Firstly, the work investigates the existing models in order to understand the causes of stocks variability. Performance of tools was determined with the Markov chain model. Then, the work provides a method to forecast production needs in terms of items and tools. An algorithm was developed to collect and process the data on the existing resources in order to compare it to the forecasted needs. Solutions were designed to identify the causes of the shortages on the production lines. In addition, by analysing the trends of the shortage of stocks and the availability of tools on workstation, a forecast of long term constraints for production is possible. The method showed promising results to identify and manage the missing items and tooling on the workstations.

  • Lejon, Alexander
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Creation and Validation of Early Stage Conceptual Design Methodology for Blended WingBody Aircraft2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The current design paradigm for developing tube-and-wing style aircraft has been well documented in literature. This research attempts to develop and val-idate a similar design methodology to what is presently utilized for tube-and-wing based aircraft, but has so far not been successfully implemented for the blended wing-body. This construction has no clear distinction between the lift generating surfaces and the cargo carrying structure. The methodology that was developed included the concatenation and validation of low-fidelity, low speed and low complexity aerodynamic models in order to allow for quick and simple analysis of a large number of possible geometries. This enables the user eÿciently determine the most promising candidate geometries for further study and/or development. Known issues with the low velocity and low com-plexity aerodynamic models include the absence of shock wave modelling, an important part in determining the aerodynamic performance of a lift generat-ing surface. The result of this work is the creation and documentation of a procedure for early-stage design of a blended wing-body airframe. However, due to convergence issues with the high-fidelity CFD solver, the methodology could not been validated for transonic flow. It can thus be only considered valid for flow velocities for which the Prandtl-Glauert correction is valid.

  • Lagemann, Benjamin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Efficient seakeeping performance predictions with CFD2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With steadily increasing computational power, computational fluid dynamics (CFD) can be applied to unsteady problems such as seakeeping simulations. Therefore, a good balance between accuracy and computational speed is required. This thesis investigates the application of CFD to seakeeping performance predictions and aims to propose a best-practice procedure for efficient seakeeping simulations.

    The widely used KVLCC2 research vessel serves as a test case for this thesis and FINEŠ/Marine software package is used for CFD computations. In order to validate the simulations, results are compared to recent experimental data from SSPA as well as predictions with potential ˛ow code SHIPFLOW® Motions.

    As for the calm water simulations, both inviscid and viscous ˛ow computations are performed in combination with three mesh refinement levels.

    Seakeeping simulations with regular head waves of different wavelengths are set-up correspondingly. Furthermore, different strategies for time discretization are investigated. With the given computational resources, it is not feasible to complete seakeeping simulations with a ˝ne mesh. However, already the coarse meshes give good agreement to experiments and SHIPFLOW® Motions' predictions. Viscous ˛ow simulations turn out to be more robust than Euler ˛ow computations and thus should be preferred. Regarding the time discretization, a fixed time discretization of 150 steps per wave period has shown the best balance between accuracy and speed. Based on these findings, a best-practice procedure for seakeeping performance predictions in FINEŠ/Marine is established.

    Taking the most efficient settings obtained from head wave simulations, the vessel is subjected to oblique waves with 160° encounter angle. Under similar wave conditions, CFD predictions of a similar thesis show close agreement in terms of added wave resistance. Compared to the previous head wave conditions of this study, added resistance in 160° oblique waves is found to be significantly higher. This underlines that oblique bow quartering waves represent a relevant case for determining the maximum required power of a ship.

    CFD and potential ˛ow show similar accuracy with respect to ship motions and added wave resistance, albeit potential ˛ow outperforms CFD in terms of computational speed. Hence, CFD should be applied in cases where viscous effects are known to have large influence on a vessel's seakeeping behavior. This can be the case if motion control and damping devices are to be evaluated, for instance.

  • Kjelldorff, Maria
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Water Current Measurements using Oceanographic Bottom LanderLoTUS?2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    oTUS is a Long Term Underwater Sensing, bottom landing, node for observations of ocean water temperatures. LoTUS measures temperature (moored to the seafloor) according to a spec-ified time schedule until, at the end of the mission, it surfaces to transmit the collected data to on shore recipients using an Iridium link. The paper presents an extension of the sensing capability to include water current velocity (speed and direction) using a robust, reliable and inexpensive Eulerian method. The method is based on the "tilting stick" principle where a combination of inertia measurement data and magnetic sensor data is used. The paper discusses the principal technique, the modeling of the system, practical considerations, and optimization of the setup for specific flow conditions along with verifying experimental data.

  • Janson, Rebecca
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    A simplified model for the design of floor structures with vibrating sources for architectural applications2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When designing a building, sound is one of the problems to take into account. Vibrating machines, such as ventilation fans, water pumps and compressors, generate structure-borne sound. The structure-borne sound travels up the structure of the building and generates sound in adjacent rooms. To be able to predict the sound radiated in the adjacent rooms when designing a building, a semi-analytical model has been developed. Using the incident vibrations from the floor plate where the vibrating machine is standing, the transmission loss in the junction between the floor plates and the wall plate is calculated. This can bed one in every junction in the building, creating a system of multiple junctions. The sound radiation to the adjacent rooms is later approximated using the velocity of the plates.The model is verified with measurements in two case studies. This shows that the model has good potential in predicting the normal acceleration amplitudes in the relevant plates. The two case studies have different geometric properties and different sources. The comparison between the model and the measurement gives similar results. The model analyses the output of the bending waves since this is the wave type that radiates sound, but longitudinal waves are present in the model. With only two case studies it is too early to say that the model works for all systems, but it could be used as a fist approach. The model, right now, is restricted to isotropic, homogeneous material without losses. A parametric study shows that the transmission loss is dependent on the ratio between the thicknesses of the floor plate and the wall plate. The ratio should be as large as possible to get a high transmission loss, but depends on how the junction is structured.