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  • Emilsson, Arvid
    et al.
    KTH, Skolan för industriell teknik och management (ITM).
    Buhrgard, Andreas
    KTH, Skolan för industriell teknik och management (ITM).
    Towards a prototype of a modular biogas system2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As of today, large unused potential for biogas production exist within the Swedish agriculturesector. The biogas production within this sector is, however, associated with several problems such as poor energy efficiency and non-profitable systems. This is to some degree due to lack of standardized technical solutions. International Micro BioGas AB (IMB AB) has been aided by KTH since 2014. This project investigates several innovations from IMB AB in regards to biogas production:

    - A mixing device- A building capturing waste heat from the digesters (building concept)- Insulation of the digester (cover concept)- Small-scale and modular package systems

    The innovations listed above are evaluated from energy, economic and environmental perspectives by doing a case study on the dairy farm Ogestad close to Gamleby, Sweden. Two cases are considered. In Case 1, the raw biogas is burned in a combined heat and power-unit (CHP) in order to produce electricity. In Case 2, raw biogas is upgraded in a small-scale upgrading unit to vehicle gas standards which is sold to the market. The results show that the mixing device is promising in terms of energy use. It is therefore recommended to move on with testing of the equipment. The cover concept and the building concept show similar performance from energy and environmental standpoints. The building concept is concluded not to be economically viable. The cost reduction by applying a modular concept where one product can be used on different sized farms is significant. However, the needed investment from the company is large. The goal of achieving a modular system is therefore concluded desirable. The subsidy from the Swedish board of agriculture covering 40 % of the investment cost, has a major impact on the profitability of the systems. Without this subsidy, the systems are not viable in terms of economy. In Sweden, the small-scale vehicle gasproduction (Case 2) was concluded the most profitable as well as the best-performing from energy and environmental standpoints.

  • Bajaj, Siddhant
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Günther-Hanssen, Erik
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Preliminary study of the fuel injector assembly capacity2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the near future the demand of the XPI fuel injectors of Scania Cummins JV assembled in Södertälje is predicted to increase. To meet this new demand the assembly line needs to increase its capacity. This paper is a preliminary study of how this capacity increment could be carried out to meet a future demand of 50% higher than today. The assembly line is semi-automated and consists of eight stations in which 100 operators are working in two shifts. The study includes situational analysis, VSM, cycle time analysis, flow analysis, line balancing and optimisation. Each station has been studied separately including all circumstances that can hinder the production of the line. The study shows how a step-by-step ramp up could be carried out for increasing the capacity of the fuel injectors. The suggestions include structural change, layout change, automation, optimisation and program logic changes.

  • Kempe, Emma
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Analys av processflödet inom ståltillverkning för olika planeringsprinciper2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Detta projekt hade som syfte att kartlägga de olika processerna vid ståltillverkning från gjutning till varmvalsning. Målet var att med hjälp av all samlad information bygga en simuleringsmodell i programvaran ExtendSim som kan vara till hjälp vid planeringen för att lägga upp den mest effektiva körplanen. Intervjuer genomfördes med anställda på företaget i olika avdelningar för att kartlägga processflödet och specificering över vad som avgör hur processvägen ser ut för en specifik produkt. Resultatet visade att processvägen till stor del beror på kundbeställningen och slutsatser kunde ej dras baserat på en viss stålsort eller dimension. Identiteter innehållande information för planerad väg genom verket behöver då finnas med i körplanen som ska testas. Stor vikt lades vid att få en inblick i hur de olika produktionsavdelningar planerar körning och vilka begränsningar som finns. Denna information kan i framtiden användas av företaget för ytterligare arbete med modellen eller för att identifiera processer som behöver effektiviseras. En del processer är invecklade med många del-processer i sig och behöver simplifieras för att hålla komplexiteten över projektet nere och för att hinna inom den satta tidsplanen. De främsta exemplen inom detta är kallslipningen och ugnen innan varmvalsning.

    Historik över vad stålverket hade tillverkat under 2018 och del av 2019 togs fram för att gå igenom och analysera mönster och mängd för olika typer av produkter. Utifrån denna data kunde genomsnittstider tas fram för olika processer. Denna data användes i ett första steg och behöver uppdateras och bli mer noggrann vid vidare användning och utveckling av modellen då denna data ej var helt tillförlitlig. Ett av de större problemen som skapar osäkerhet i modellen är det material som oplanerat behöver gå en annan väg igenom flödet på grund av processer som presterar under planerad nivå (stor felmarginal). Detta baserades på statistik och innebär en osäkerhet i tillförlitligheten. Data framtagen specifikt med detta syfte borde ersätta den befintliga vid framtida uppgradering av modellen. En modell konstruerades enligt kriterierna och applicerades på fyra olika körplaner uppbyggda på olika sätt. Då de simplifierade processerna och eventuellt felaktiga ledtidsdata var konstanta kunde resultatet från olika körplaner ändå jämföras med varandra för en första uppskattning av effektiviteten. Resultat presenteras i form av grafer och en guide över användning av modellen konstruerades för användning av de anställda på Outokumpu utan kunskap inom ExtendSim.

  • Lekkas, Sotirios
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Life Cycle Assessment on Bridge Abutments: Automated Design in Structural Enginee2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Life Cycle Assessment (LCA) is the globally the most recognised method for quantifying theimpact the a product or service has on the environment through its whole life-span. Theconstruction sector plays a key role in the depletion of the natural resources and the energyconsumption on the planet. Thus it is fundamental that an environmental assessment tool likeLCA should be in close cooperation with the construction process.This thesis focuses on the environmental impact of bridge abutments, and can be divided in twoparts.The rst one focuses on enhancing the automated design in the construction eld. A Python codeis created that focuses on creating the geometry of any type of bridge abutment and conductingthe calculations for the required concrete and reinforcement. The process is attempted to becomecompletely automated.The second part introduces three alternative designs for a bridge abutment that attempt to havethe same structural properties and cooperate successfully with the superstructure, while at thesame time utilize as little material as possible. The possible reduction in material is quantiedin environmental terms after an environmental impact assessment is performed.The results show that dierent designs can have a great impact on the reduction on the materialconsumption and on the impact that the whole structure has on the environment. The resultsin this study might provide the designers with valuable motivation and guidelines to achievehigher sustainability standards in the future.

  • Disputas: 2019-10-11 10:00 V2, Stockholm
    Umsonst, David
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Tuning of Anomaly Detectors in the Presence of Sensor Attacks2019Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Critical infrastructures, such as the power grid and water distribution networks, are the backbone of our modern society. With the integration of computational devices and communication networks in critical infrastructures, they have become more efficient, but also more vulnerable to cyberattacks. Due to the underlying physical process, these cyberattacks can not only have a financial and ecological impact, but also cost human lives. Several reported cyberattacks on critical infrastructures show that it is vital to protect them from these attacks. Critical infrastructures typically rely on accurate sensor measurements for optimal performance. In this thesis, we, therefore, look into attacks that corrupt the measurements.

    The first part of the thesis is concerned with the feasibility of a worst-case sensor attack. The attacker's goal is to maximize its impact, while remaining undetected by an anomaly detector. The investigated worst-case attack strategy needs the exact controller state for its execution. Therefore, we start by looking into the feasibility of estimating the controller state by an attacker that has full model knowledge and access to all sensors. We show that an unstable controller prevents the attacker from estimating the controller state exactly and, therefore, makes the attack non-executable. Since unstable controllers come with their own issues, we propose a defense mechanism based on injecting uncertainty into the controller. Next, we examine the confidentiality of the anomaly detector. With access to the anomaly detector state, the attacker can design a more powerful attack. We show that, in the case of a detector with linear dynamics, the attacker is able to obtain an accurate estimate of the detector’s state.

    The second part of the thesis is concerned with the performance of anomaly detectors under the investigated attack in the first part. We use a previously proposed metric to compare the performance of a χ2, cumulative sum (CUSUM), and multivariate exponentially weighted moving average (MEWMA) detectors. This metric depends on the attack impact and average time between false alarms. For two different processes, we observe that the CUSUM and MEWMA detectors, which both have internal dynamics, can mitigate the attack impact more than the static χ2 detector. Since this metric depends on the attack impact, which is usually hard to determine, we then propose a new metric. The new metric depends on the number of sensors, and the size of an invariant set guaranteeing that the attack remains undetected. The new metric leads to similar results as the previously proposed metric, but is less dependent on the attack modeling. Finally, we formulate a Stackelberg game to tune the anomaly detector thresholds in a cost-optimal manner, where the cost depends on the number of false alarms and the impact an attack would cause.

  • Nyman, Johannes
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Optimization of case-hardening depth for small gears2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The optimization of case hardening depth for small gears was investigated with the use of Abaqus and the subroutine DANTE to simulate the formation of the microstructural phases, resulting in residual stresses and increased hardness. This was done with a step wise increment of the carburizing time, resulting in a theoretical maximum for compressive residual stresses at the surface. The heat treatment parameters were then used for case hardening two gears with different carburizing times. The heat treated gears were then tested for tooth root bending fatigue. The fatigue testing resulted in a fatigue limit increase, where the gear with largest simulated compressive stress showed the highest fatigue limit.

     

    Both the heat treated gears were hardness tested and compared with the conducted simulations resulting in an underestimated hardness. An investigation to see whenever the simulations could predict the fatigue outcome beforehand with a probabilistic model was put into place. This resulted in an underestimated fatigue limit in relation to the raw fatigue data.

  • ODHIAMBO, EVANS OTIENO
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Evaluation of Signal Optimization Software: Comparison of Optimal Signal Pans from TRANSYT and LinSig – A Case Study2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The design of traffic signal control plan is directly related to the level of traffic congestion experienced both at the junction level and the network particularly in urban areas. Ensuring signals are well designed is one of the most cost-effective ways of tackling urban congestion problems. Signal time plans are designed with the help of signal optimization models. Optimization can either be done for multiple or single objectives and is formulated as a problem of finding the appropriate cycle lengths, green splits, and offsets. Some of these objective functions include; better mobility, efficient energy use, and environmental sustainability. LinSig and TRANSYT are two of the most widely used traffic signal optimization tools in Sweden. Each of them has an inbuilt optimization function which differs from the other. LinSig optimizes based on delay or maximum reserve capacity while TRANSYT optimization is based on performance index (P.I) involving delay, progression, stops and fuel consumption.This thesis compared these optimization models through theoretical review and application to a case study in Norrköping. The theoretical review showed that both TRANSYT and LinSig have objective functions based on delay and its derivatives. The review also showed that these models suffer from the inability to accurately model block back as they are based on the assumption of vertical queuing of traffic at the stop line. Apart from these similarities, these two models also have significant variations with respect to modeling short congested sections of the network as well as modeling mixed traffic including different vehicle classes, pedestrians, and cyclists.From the case study, TRANSYT showed longer cycle time compared to LinSig in both scenarios as its optimization objectives include both delay and stops while LinSig accounts for only delay. The Allocation of phase green splits and individual junction delay was comparable for undersaturated junctions while congested network sections had significant differences. Total network delay was, however, less in LinSig compared to TRANSYT. This could be attributed to different modeling criteria for mixed traffic and congested network in addition to the fact that cyclists were not modeled in TRANSYT. VISSIM simulation of the two-signal time plans showed that network delay and queue lengths from TRANSYT signal timings are much less compared to LinSig time plans. A strong indication of better signal coordination.

  • Bårman, Sofia
    KTH, Skolan för industriell teknik och management (ITM), Lärande.
    Den didaktiska formeln för(Matematik)Idrottselev: En diskursanalys på ett idrottsgymnasium2019Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Sverige finns det Riksidrottsgymnasier och Nationella idrottsutbildningar som erbjuder ett utbildningsprogram med specialidrott för att elitidrottande ungdomar ska kunna kombinera idrott och studier. Ungdomarna ska få möjlighet att utvecklas både inom sin idrott och inom sin utbildning och på så sätt bli ”vinnare i långa loppet” med både en idrottskarriär och sedan även en yrkeskarriär som de lagt grunden till med studier under idrottsåren. För att ungdomar ska lyckas med elitidrott och studier är det viktigt att se till helheten. Tidigare forskning inom ”dubbla karriärer” tar utgångspunkt från det holistiska perspektivet som beskriver betydelsen av balans mellan idrott, skola och privatliv. Studierna nämner helheten som viktig för ungdomar ska må bra och kunna prestera i sin idrott och i sin utbildning. De olika forskningsstudierna utgår och lägger tyngdpunkten på idrottsdelen, idrottsmiljöerna och tränare. De pekar på betydelsen av skolan och på betydelsen av helheten idrott, skola och privatliv men går ej på djupet med hur lärarens undervisning eller elevens lärande ska utformas för bästa resultat. Diskursen som analyseras i detta arbete är ”matematikundervisning på ett idrottsgymnasium”. Forskningsfrågan som ställs och som formar diskursen lyder: Vilka är de didaktiska perspektiven i idrottselevernas utbildningsmiljö, specifikt inom matematikundervisning och vad görs viktigt i matematikundervisningen sedd som diskurs? Matematiklärarna och idrottseleverna sätts i fokus och studien undersöker, hur de beskriver olika företeelser när de ger sin bild av matematikundervisningen på skolan. Studien tar utgångspunkt från det didaktiska perspektivet/lärarperspektivet i idrottselevernas utbildningsmiljö.

    Data samlades in genom intervjuer med matematiklärare och en enkät till idrottselever på ett Riksidrottsgymnasium med cirka 60 idrottselever, under vårterminen 2019. I analysresultatet framstår diskursens normer, högt värderade ståndpunkter och dilemma som fem teman: ”det viktiga matematikämnet”, ”den goda idrottseleven”, ”dilemmat runt idrottselevens frånvaro”, ”strategier för stöd” och ”studieformens otydlighet”. Slutsatsen pekar på att det så tydligt frammanas en ideal bild av en framgångsrik elev, att matematikämnet värderas så viktigt och svårt utifrån sin tradition och att den specifikastudieformen för matematikundervisning för idrottselever saknar tydlig form. Studieformen kan beskrivas som lärarledd klassrumsundervisning kompletterad med olika anpassningar för att underlätta för idrottselevernas självstudier. Studiens diskursiva analys beskriver också vad som ses som framgångsfaktorer, vilket sammanfattas i idrottselevernas stora egna ansvar, motivation och förmåga att planera in och genomföra självstudier samt matematiklärarnas olika anpassningar och stöd för att underlätta idrottselevernas självstudier.

  • Eriksson, Oskar
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Larsson, Mattias
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Increasingly Complex Environments in Deep Reinforcement Learning2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this thesis, we used deep reinforcement learning to train autonomous agents and evaluated the impact of increasing the complexity of the training environment over time. This was compared to using a fixed complexity. Also, we investigated the impact of using a pre-trained agent as a starting point for training in an environment with a different complexity, compared to an untrained agent. The scope was limited to only training and analyzing agents playing a variant of the 2D game Snake. Random obstacles were placed on the map, and complexity corresponds to the amount of obstacles. Performance was measured in terms of eaten fruits.

    The results showed benefits in overall performance for the agent trained in increasingly complex environments. With regard to previous research, it was concluded that this seems to hold generally, but more research is needed on the topic. Also, the results displayed benefits of using a pre-trained model as a starting point for training in a different complexity environment, which was hypothesized.

  • Häger, Alvin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Torkkeli-Johansson, Adam
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Simulated evolution of food foraging strategies of army ants2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Many ant species make use of pheromone trails to coordinate food raids, which result in emergent behaviour in the form of complex, dynamic foraging patterns. The foraging behaviour of army ants, in particular, can be modelled as a ’central foraging problem’, where ants leave the nest to collect and bring back food. This thesis implements a previously defined model for foraging army ants to investigate what ant behavioural parameters lead to optimal solutions for three different types of food sources. These food sources are: small and common, large and scarce, and a combination of both of these food sizes and distributions. The model is also extended to investigate similar scenarios where a foraging ant colony is competing with another colony for resources. To find optimal behavioural parameters, the parameter space is searched using a simple evolutionary algorithm. This is used to successively ’evolve’ parameters to find optimal solutions. The results show that the optimal parameters, as well as foraging patterns that emerge, changed when a competing colony was present. The degree to which a solution found can be deemed ’optimal’ was highly dependent on the specific scenario. Finally, the evolution of foraging strategies for small and common was more successful than that of large and scarce. This research has applications in both natural science and computer science, where applications in the former involve, for example, swarm intelligence and optimisation algorithms.

  • Reitz, Fabienne
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Weaknesses and risks of the Consumer Internet of Things2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

     The Consumer Internet of Things (CIoT) is a term to describe everyday items connected to the internet. The number of CIoT devices is growing rapidly and with it comes a number of security problems. One way to tackle these security issues is by learning from mistakes and to be aware of the risks at hand at both production and consumer level.

    This report examines vulnerabilities from the years 2008-2018 in the National Vulnerability Database (NVD). With the Common Vulnerability Scoring System (CVSS) and the Common Weakness Enumeration (CWE) the following questions are answered: Which are the most common types of vulnerabilities in CIoT products, what risks do they pose and is there evidence of a connection between type of product and type of vulnerability?

    The study found that the most common weaknesses were CWE-119, CWE200 CWE-20 and CWE-264. However, the vulnerabilities of type CWE-119 turned out to be highly concentrated to Apple products and do not reflect the overall trends. The before mentioned weaknesses pose risks to users’ confidentiality, integrity and the availability of the software (CIA). The CWEs with the greatest risk of exploitation were CWE-264 with the highest percentage of complete impact on the CIA attributes, and CWE-119 with lower percentage of complete impact but with far more occurrences. The study found no conclusive answer whether there is a connection between products and weaknesses, but an indication of a relation between certain CWEs and the company Apple. Further intensive and recurring studies should be conducted in the field.

  • Söderberg, Anna
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Wieslander, Johan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Evaluating the Effects of using a Fuzzy Controller in Timetable Generation for Commuter Rail Services2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Scheduling trains is a hard problem where current solutions typically create timetables that create undesirable amounts of delay for the trains that use them. This study considers the fact that conventional timetables, which only use fixed intervals to schedule trains, might not be optimal for minimising the delay and travel time of passengers. In this study, we compare this ”simple” timetable with timetables generated via a fuzzy controller which has access to information about the flow of passengers throughout the day. The hypothesis is that this fuzzy controller therefore becomes more ”intelligent”. We evaluate the performance using a custom-built simulator that measures the average delay and travel time of the passengers. We conclude that the fuzzy controller can generate timetables that quickly adapt to passenger demands and show favourable resource usage over the simple timetable. However, more research is needed on the input variables and their usage within the fuzzy controller to further optimise the performance.

  • Åberg, Oscar
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Sparf, Edvin
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Validating the Meta Attack Language using MITRE ATT&CK matrix2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    When more and more devices are getting connected to each other and to the internet, the security of such devices becomes increasingly important. For large organizations with hundreds or even thousands of connected devices, it can be hard to determine the weak spots of the network in terms of security. A way of finding these weak spots is by using threat modelling. One language which can be used for this is the Meta Attack Language(MAL). The purpose of this report is to study which types of cyber attacks can be expressed with MAL. To do so eleven different attack techniques from the cyber attack database MITRE ATT&CK matrix are implemented in MAL. The report shows that many different attacks can be implemented in MAL. Since all of the randomly selected attacks were possible to implement in MAL this suggests that it is possible to implement all of the attacks from the MITRE ATT&CK matrix in MAL.

  • Hultgren, Gustav
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Assessment of fatigue for laser-scanned weld surfaces: Correlation between weld geometry and fatigue initiation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The work conducted in this project proposes a method to determine the location of fracture initiation for non-load carrying fillet welds based on continuous geometry measurements. Measurements were carried out on welded specimens using a laser line triangluator together with the weld quality evaluation software qWeld from Winteria®. The 119 specimens produced were after scanning fatigue tested until failure. The fracture surfaces have been investigated in order to find the most probable location(s) of fracture initiation. This data was then used to fit the proposed model parameters used to analytically predict the point(s) of fracture initiation. Local weld geometry measurements were extracted from the predicted fracture initiation location(s) in an effort to analyse the correlation between local weld geometry and fatigue life. This showed that fatigue life and leg length were positively correlated and that strong correlations exists between the individual geometrical parameters. New specimens were produced to test the fitted data of the proposed model, this data was however inconclusive as the new specimens had a high ratio of weld defects.

  • Sorsh, Frans
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Assessment of creep damage in Fe-Ni-Cr alloys2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    It is only a matter of time before components working in high temperature environments fail due to creep. Design for creep is therefore of vital importance to maximize the lifetime of components and reduce costs that may arise from maintenance and replacement of components. This thesis aims to use metallographical methods and finite element modeling to assess creep damage in a hydrogen reformer. The decommissioned reformer, made of Fe-Ni-Cr alloys, was investigated thoroughly via replica testing, hardness measurements as well as finite element modeling of the welds. An extended literature review was performed to gain a better understanding of creep in Fe-Ni-Cr alloys, welds and the modeling of creep generally. The microstructures of samples from the reformer were analyzed and mapped out in terms of creep damage which were then compared to a creep analysis of the welds with a simulation time of 100 000 h. The FE results yielded high stresses and creep strains with a maximum of 0.95% in the boundaries of the welds which gave realistic representations of strain distributions when compared to the metallographical results. Hardness measurement indicated that a relatively narrow zone with altered mechanical properties is present along the weld boundaries. This area, called the heat affected zone, was found to be most affected by creep with microcracks reaching maximum lengths of 2 mm. The creep strains obtained from simulation did not fall in line with the observed creep damage, it was thus concluded that a material model that considers tertiary creep would yield a more realistic representation in FEM for Fe-Ni-Cr alloys.

  • Lehtinen, Silja
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Thermodynamic and Economic Evaluation of Hybridization Biomass-solar for a Cogeneration Power Plant in a Cuban Sugar Mill, George Washington2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This study evaluates the thermodynamic and economic performance of hybridization of biomass-solar for a cogeneration power plant in a Cuban sugar mill, George Washington. The evaluation is performed by varying the parameters of the thermal power block and considering scenarios with 1) bagasse and marabú, 2) bagasse and solar field, and 3) bagasse, marabú and solar field as heat sources for the cogeneration cycle. The most feasible configuration combines all the three heat sources having the superheated steam parameters of 100 bar and 540 ⁰C and the solar field aperture area of 88,560 m2 using SkyTrough collectors. The NPV for the proposed system is 30.97 million USD which indicates that it is economically feasible and the LCOE of 0.091 USD/kWh is in the range of a typical LCOE for biomass electricity generation with a stoker boiler (0.06 – 0.21 USD/kWh).

  • Solheim, Ulrika
    KTH, Skolan för industriell teknik och management (ITM).
    Will green banking unlock a sustainibility transition towards a low-carbon economy?: The perspective of a member-owned bank in Sweden2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the climate change discussion, there is a broad consensus about the importance of support from the financial industry when it comes to supporting changes towards a more sustainable society. However, investments in the society supporting a transition towards a low-carbon economy are still waiting to become unlocked. This thesis aims to provide an understanding of a possible sustainability transition towards a low-carbon economy within the Swedish financial industry. To fully understand a possible change, this study has investigated the dynamics of the financial industry from the perspective of a member-owned bank in Sweden. Hence this study seeks to explore a fundamental and comprehensive change, the theoretical framework of socio-technical transition and the multi-level perspective is used. This contributes to a vast mapping of the financial industry and a better understanding of the dynamics of social change and innovation, such as a low-carbon economy transition.

    To gain in-depth knowledge, a case study was performed. Both qualitative and quantitative data was collected through semi-structured interviews and data from the case company’s customer database. The carbon footprint of the case company bank’s loan portfolio was calculated and analysed through a sensitivity analysis. This was done in the aim to gain deeper insights about how actions from a bank could contribute to a low-carbon economy. The empirical findings in this thesis showed that a bank does have the ability and power to contribute to a lower carbon footprint in a bureaucratic and stable regime as the financial industry. However, this responsibility could be hard to put at a single actor. As the financial industry has a strong carbon lock-in, the approach has to be long-term. The actions that could enable a sustainability transition within the financial industry seems to be a collection of many different transition pathways. By remaining the landscape pressure and the development of niche innovations, a long-term sustainability transition seems imaginable. By collecting the forces of regulatory work along with collaboration among incumbent actors and increasing development of new low-carbon financial products, there is positive movement. With patience and an attitude change, the financial industry can see a sustainability transition in the horizon.

  • Petäjävaara, Agnes
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Dispelling inertia towards behavior-driven development: An assessment tool for development practice readiness2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Behavior-driven development (BDD) is a development practice focusing on behaviors and requirements from users and stakeholders. It is designed to develop behaviors which contribute directly to system outcomes. BDD encourages multiple stakeholders to collaborate by minimizing communication gaps and create a shared understanding of the project between technical and non-technical speakers. As a result, the development process becomes faster and the cost lower. Although BDD has many benefits, there are teams who feel inertia towards using it as their main development practice.This thesis work took place at a company with a strong agile foundation. It had the goal to investigate reasons why teams feel inertia against BDD, and thus contribute to BDD research and assist the company. The assumption that positive motivation would help in dispelling inertia was the idea behind this thesis work, and that a stronger motivation for a practice can be achieved by assessing a team’s suitability for it. To reach the goal of the thesis a qualitative research methodology was used, with a focus on obtaining a better understanding of opinions and behaviors that exist, with rounds of interviews and forms as the main method of data collection. Interviews were also consistently used throughout the thesis work to validate that it followed the right track.The inertia which teams at the company have experienced was clustered into different dimensions. These dimensions were used to develop a self-assessment tool intended to help people starting a project to assess how well BDD might fit their context. It allows people to assess their inertia in the different dimensions identified, and as well as attempting to give an overall guide to readiness, also giving some recommendations where gaps could be identified.The deliverable of the thesis work is the tool for managing inertia against BDD. It was developed in a spreadsheet-format for quick development and easy access for multiple users. However, it is important to highlight that this tool focuses on agile autonomous teams. The tool is not about forcing the development practice on someone but rather acts as an aid in giving insight into how well BDD could work for a specific project and team. Finally, to grasp the validity of the tool teams who had previous success developing projects using BDD at the company were able to try it out to see how well it reflected their project reality. The tool also got tested on teams who felt strong inertia towards BDD, to verify whether it helped them manage it or not.

  • Eriksen, Rúni
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Energy Consumption of Low Power Wide Area Network Node Devices in the Industrial, Scientific and Medical Band2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Low-Power Wide-Area Networks, LPWANs, achieve long communication ranges with a low energy consumption by communicating at low bit rates. Most LPWAN devices are battery powered and are required to operate for an extended period of time, which stresses the requirements for energy efficiency. This thesis investigates the energy consumption of LPWAN devices operating in the Industrial, Scientific and Medical, ISM, band and how use cases affect the consumption. Specifically, LoRa/LoRaWAN and Sigfox are examined. Their key characteristics are described and energy consumption is modelled. The models are verified by comparing the model outputs with measured power consumption of LoRa and Sigfox devices. Through the models, design parameters are investigated with regards to consumption, and product lifetime are estimated. The influence of use cases on energy consumption is explored by measuring the Package Delivery Ratio, PDR, at different ranges using various bit transmission rates.The results showed that the bitrate, data redundancy and protocol overhead were among parameters which could be used to optimise energy efficiency. It was also shown, that the device lifetimes could be significantly increased by increasing the transmission interval and removing message acknowledgements. Realistically, LoRa devices can have a lifetime of more than 10 years and Sigfox 3 years, using a 2800 mWh battery. The use case tests showed that a 100 % PDR should not be expected at any bitrate, but lower bitrates and messaging redundancy increase the likelihood of a successful package delivery. Hence, there is a tradeoff between low energy consumption and range/reliability. Additionally, it was found that a low node to gateway distance and a high gateway density increase the probability of a successful transaction. Thus, the power consumption is tightly coupled to the network configuration.

  • Gong, Xuwei
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Security Threats and Countermeasures for Connected Vehicles2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the rapid development of connected vehicles, automotive security has become one of the most important topics. To study how to protect the security of vehicle communication, we analyze potential threats for connected vehicles and discuss countermeasures to mitigate these threats. In this thesis, we examine 25 services that connected vehicles can provide. Entities, connections, and message flows in these services are investigated and synthesized into a vehicle network structure. The 25 services are divided into six use cases including: infotainment service, remote monitoring, device control, Vehicle-toeverything (V2X), diagnostics service, and in-vehicle Intrusion Detection System (IDS). We establish communication models for these use cases and analyze the potential threats based on Confidentiality, Integrity and Availability (CIA) criteria. We discuss possible countermeasures that can mitigate these threats based on existing network security techniques. Each alternative countermeasure’s advantages and limitations are presented. To filter possible attacks, we investigate and design firewalls in four components of a vehicle: Dedicated Short-Range Communications (DSRC) module, gateway, Telematic Control Unit (TCU), and Human-Machine Interface (HMI). We also simulate a firewall for an HMI application by building a communication model in Python.

  • Puthucode, Rahul
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Neutralization of acidic wastewaters with the use of landfilled Electric Arc Furnace (EAF) high-alloyed stainless-steel slag: An upscale trial of the NEUTRALSYRA project2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The landfilling of slag obtained from the high alloyed Electric Arc Furnace (EAF) steel making process, constitutes an environmental treat for society as well as an economical problem for the companies producing it, due to the costs related to waste management practices. Conventional methods of slag recycling are abundantly used among the steelmaking business, but due to their particular physical properties, high- alloyed EAF slags cannot be properly valorized. Moreover, the pickling process that high-alloyed EAF steels undergo to, generates acidic wastewaters, that need to be collected and neutralized, before they can be recirculated into the natural water streams. For such a task, steel mills currently utilize slaked lime (a Ca rich mineral) to raise the pH and to remove any metal particles dissolved into the wastewaters. Slag contains high amount of Ca; therefore, it has already been tested as a slaked lime replacement. In fact, previous studies conducted at the Material Science and Engineering department at KTH Royal Institute of Technology showed, on a laboratory scale, that slag has the potential to replace lime for the neutralization and purification of the acidic wastewaters. This Master’s thesis project aims at upscaling the volumes of wastewaters to be tested, about 70 to 90 folds of the one from previous research, bridging the gap between laboratory tests and the industrial scale.

    The thesis is divided into three tranches, a first part where a water-salt solution conductivity trials were carried out, to model the behavior or slag dispersion in the acidic wastewaters. After the results obtained from the conductivity trials, neutralization trials with slag and the lime product currently in use by the company, were carried out at the neutralization plant in Outokumpu Stainless, Avesta (Sweden). The neutralization trials were carried out with 70 and 90 liters of acidic wastewaters and in order to perform the trials on site, the slag sample was dried and later sieved to a particle size of less than 350μm. Moreover, data was analyzed and compared to previous studies in order to have a clearer understanding regarding the neutralization efficiency of the slag, especially whether or not the technology would had worked on upscaled volumes. Additionally, the project checked if it was possible to find a generalized relationship between the mass of slag and volume of wastewaters required for the neutralization process. Slag demonstrated to be able to buffer the pH to the target values of 9, while also showing an almost linear trend compared to previous studies. The reaction progress between slag, lime, and the acidic wastewaters was also analyzed.

  • Ounsi, Karim
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Geographically Weighted Regression as a Predictive Tool for Station-Level Ridership: The Case of Stockholm2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis studies a new regression method, Geographically Weighted Regression (GWR)to predict ridership at the station level for future stations. The case study of Stockholm’s blue lineis used as new stations will be built by 2030. This paper is written in English.Historically, linear regression methods, independent of the geographical location of theobservations, was and is still used as the Ordinary Least Square regression method. With the riseof GIS-softwares these last decades, geographically dependent regression can be used and previouspreliminary studies have shown a dependency between ridership and location of the station withinthe network.GWR equations for new stations are determined and used to predict their respectiveridership. GIS-data was collected using Geodata and Traffikverket (Traffic Authority) andridership as well as socio-economic related material for the base year of 2016 was used in order todetermine, first, significant variables from a group of candidate ones (Workers, number of buslines and type of change were chosen) and, second the OLS and GWR equations. Significances ofboth models were compared and the OLS equation was used in order to determine the hypotheticalridership of the new stations if they were present in 2016. GWR equations were then determinedusing these calculated ridership of these new stations. Having all GWR equations (each stationhaving its own equation), ridership was thus predicted for the new stations for 2030 usingassumptions and planned, programmed development around the stations (population, apartment tobe built…) and compared with the official predictions.The results show that the GWR method, generally, overpredicts ridership when comparedto the official predictions. Many reasons can explain this overprediction like the assumptions madewith regards to the number of buses as well as the method followed to calculate the number ofworkers around each station.Three main conclusions were drawn for this case study. One main conclusion, specific forthis study and two other, more general, conclusions were deduced from this study. First, GWR isa good predicting tool for future stations that are close to most currently available stations. Second,GWR is a good predicting method for stations where limited changes in the future environmentwill occur.

  • Disputas: 2019-10-11 10:00 Air & Fire, Solna
    Björk, Sara
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi.
    Droplet microfluidics for screening and sorting of microbial cell factories2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Cell factories are cells that have been engineered to produce a compound of interest, ranging from biopharmaceuticals to biofuels. With advances in metabolic engineering, the number of cell factory variants to evaluate has increased dramatically, necessitating screening methods with increased throughput. Microfluidic droplets, which can be generated, manipulated and interrogated at very high throughput, are isolated reaction vessels at the single cell scale. Compartmentalization maintains the genotype-phenotype link, making droplet microfluidics suitable for screening of extracellular traits such as secreted products and for screening of microcolonies originating from single cells.

     

    In Paper I, we investigated the impact of droplet microfluidic incubation formats on cell culture conditions and found that syringe and semi open incubation resulted in different metabolic profiles. Controlling culture conditions is key to cell factory screening, as product formation is influenced by the state of the cell.

     

    In Paper II and III, we used droplet microfluidics to perform screening campaigns of interference based cell factory variant libraries. In Paper II, two S. cerevisiae RNAi libraries were screened based on amylase secretion, and from the sorted fraction genes linked to improved protein secretion could be identified. In paper III, we screened a Synecosystis sp. CRISPRi library based on lactate secretion. The library was sorted at different time points after induction, followed by sequencing to reveal genes enriched by droplet sorting.

     

    In Paper IV, we developed a droplet microcolony-based assay for screening intracellular triacylglycerol (TAG) in S. cerevisiae, and showed improved strain separation compared to flow cytometry in a hypothetical sorting scenario. By screening microcolonies compartmentalized in droplets, we combine the throughput of single cell screening methods with the reduced impact of cell-to-cell noise in cell ensemble analysis.

  • Berglöf, Olle
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Jacobs, Adam
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Effects of Transfer Learning on Data Augmentation with Generative Adversarial Networks2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Data augmentation is a technique that acquires more training data by augmenting available samples, where the training data is used to fit model parameters. Data augmentation is utilized due to a shortage of training data in certain domains and to reduce overfitting. Augmenting a training dataset for image classification with a Generative Adversarial Network (GAN) has been shown to increase classification accuracy. This report investigates if transfer learning within a GAN can further increase classification accuracy when utilizing the augmented training dataset. The method section describes a specific GAN architecture for the experiments that includes a label condition. When using transfer learning within the specific GAN architecture, a statistical analysis shows a statistically significant increase in classification accuracy for a classification problem with the EMNIST dataset, which consists of images of handwritten alphanumeric characters. In the discussion section, the authors analyze the results and motivates other use cases for the proposed GAN architecture.

     

  • Vitek, Viktor
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Syed Shah, Taqui
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Implementing a Nudge to Prevent Email Phishing2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Phishing is a reoccurring issue, which uses social engineering as an attack strategy. The prevention of these attacks is often content-based filters. These solutions are however not always perfect, and phishing emails can still be able to get through the filters. We suggest a new strategy to combat phishing. The strategy is a technical platform which uses the psychology concept nudge. Nudge is a concept that can be used to change a certain behaviour, in this case to make people more cautious when reading their emails.The objective of this thesis is to suggest a nudge using a technical platform regarding possible desensitization. The nudge aims to change email related behaviours to more healthy ones. To get indications if the nudge has benefits, a qualitative survey was made. When using a psychology-based solution, one must address the possibility of desensitization. To minimize possible desensitization, a quantitative analysis was made where different ways to minimize desensitization were assessed. Data for this analysis was gathered by a simulation modeling, where the simulation aimed to replicate a user performing email related events.The conclusion of the simulation results showed that a whitelist approach was the most appropriate for our nudge. The approach minimized the chance of possible desensitization while having a low risk of not performing a nudge when needed. The conclusion of the survey results was that there was an indication of behavioural change and that there existed a risk of possible desensitization.

  • Lindell, Ida
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Analysis of the flow of secondary steam through a reheater using 3D CFD2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this study 3D CFD was used to study the mass flow distribution in a reheater in a nuclear power plant. The aim was to see if 3D-modeling provide different results than traditionally used 1D-analysis.

    Models with detailed geometry were created for a section of the tube package in the reheater to obtain pressure drop coefficients. The set up of the model for pure cross-flow over the tubes was first validated against an experiment by Ward [33]. The model showed good agreement with the experimental data for pressure drop and heat transfer, with both unsteady simulations using LES and steady simulations using the SST k - w model. It also showed that using the empirical correlations by Ward and Young [32] and Rabas et al. [22], without any experimental data for the tube bank, gave an overestimation of the pressure drop.

    The pressure drop coefficients obtained from the tube package simulations were used to model the tube package in the reheater as a porous medium. A set of perforated plates in the reheater needed to be modeled as a porous medium as well. These plates were originally meant to be mounted on the inlet side of the tube package to even out the mass flow distribution. However, due to a manufacturing error they were now mounted on the outlet side. A set of simulations using the SST k - w for a part of the plate geometry gave the required pressure drop coefficients.

    With all coefficients for the porous medium obtained a full scale model of the reheater was created. In the 3D-model the IAPWS-IF97 formulation was used to model the pressure and temperature dependent properties of the steam. Both the SST k - w model and DES were used for turbulence closure. A 1D-simulation of the reheater was also performed using RELAP5.

    The 3D-simulations showed a larger difference in the mass flow distribution between the upper and lower part of the tube package than the 1D-model. The 1D-model showed a clear connection between the pressure drop over the perforated plates and the mass flow distribution. However, in the 3D-model the mass flow distribution appeared to also be affected by other properties.

  • Sekandari, Zohib
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Saleh, Shahin
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Emergency Department Triage Prediction of Emergency Severity Index using Machine Learning Models2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Study Objective: The emergency department (ED) in the United States strongly rely on subjective assessment of patients. This study seeks to evaluate an electronic triage system based on machine learning models that can predict the patients emergency severity index (ESI).

    Methods: A dataset containing 560 486 patients triage data was investigated.Three different machine learning models was tested and evaluated. A crossvalidation table and a confusion matrix was conducted from each of the models. The precision rate, recall rate and f1-score were calculated and reported.

    Result: The Gradient Boosting model returned an accuracy rate of 68%. The random forest model returned an accuracy rate of 66%. The Gaussian Naive Bayesmodel returned an accuracy rate of 25%.

    Conclusion: The model that best predicted the ESI-level is the GradientBoosting model. Further testing is needed with better computational power since we could not train our model with the whole dataset.

  • Landström, Jessica
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Blockkedjeteknikens förutsättningar i stålindustrin2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Blockkedjeteknik är en trendig och omdiskuterad teknik som både hyllas och sägs kunna komma att revolutionera samhället. Samtidigt avvisas tekniken som en överskattad hajp av dess kritiker. Syftet med detta examenarbete är att beskriva grunderna i blockkedjetekniken och att lyfta fram var inom SSAB den potentiellt skulle kunna komma till nytta. Två givna avgränsade områden (valsning och logistikdelen ”slutprodukt till kund”) utvärderas också utifrån perspektivet hur blockkedjeteknik där skulle kunna tillgodose SSABs aktuella behov. En litteraturstudie ligger till grund för beskrivningen av blockkedjetekniken. De två givna avgränsade områdena är utvärderade utifrån blockkedjeteknikens egenskaper identifierade i litteraturstudien och de behov som identifierats inom respektive givna område. Resultatet är att blockkedjetekniken är i en utvecklingsfas och måste mogna innan den kan appliceras fullt ut. De eventuella blockkedjelösningar som rekommenderas i examensarbetet är av så kallad privat och begränsad karaktär. En publik obegränsad blockkedja bedöms inte vara nödvändig då de aktörer som skulle använda blockkedjan är begränsade i antal och alla kan antas ha incitament för att anses som pålitliga.

    De identifierade områdena inom SSAB som lyfts fram som lämpliga för en blockkedjelösning är logistikkedjan och produktdata. En blockkedjelösning för de involverade aktörerna i logistikkedjan skulle innebära en ökad spårbarhet och transparens, samt skapa förutsättningar för optimering av processer genom delning av data mellan de olika aktörerna. En blockkedjelösning för produktdata är av mer visionär karaktär och de fördelar en sådan lösning skulle innebära är även här spårbarhet och transparens med effekter som skulle kunna skapa rättvisare handeloch effektivare återbruk eller återvinning. Resultatet av utvärderingen av det givna avgränsade området valsning är att en blockkedjelösning inte är aktuell då behovet av produktspårbarhet är internt. En internt distribuerad databas, tekniken som blockkedjan bygger på, kan enklare tillmötesgå detta behov. Resultatet av utvärderingen av den givna avgränsade logistikdelen slutprodukt till kund är en ökad spårbarhet, transparens och skapar förutsättningar för optimering av processer genom delning av data mellan de olika aktörerna. En av de största utmaningarna är att få till det viktiga samarbete som är enförutsättning i den gemensamma distribuerade tekniklösning som blockkedjan är. Blockkedjans potential uppnås av synergier mellan företag och att de involverade aktörerna enskilt kan dra nytta av de fördelar som uppstår.

  • Rodrigues, Diogo
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Hjalmarsson, Håkan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Stability and Performance Analysis of Control Based on Incomplete Models2019Inngår i: IFAC-PapersOnLine, E-ISSN 2405-8963, Vol. 52, nr 1, s. 874-879Artikkel i tidsskrift (Fagfellevurdert)
  • Legeby, Ann
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur, Stadsbyggnad.
    Koch, Daniel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur, Stadsbyggnad.
    Miranda Carranza, Pablo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur, Stadsbyggnad.
    Schools at 'Front Row': Public buildings in relation to societal presence and social exclusion2019Inngår i: Proceedings of the 12th Space Syntax Symposium, Beijing: Beijing Jiaotong University , 2019, s. 287-2:1-287-2:19Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In analyses of affordances and opportunities in different neighbourhoods it is found that access to public buildings and a well-functioning public space are of outmost importance. This is found to be especially important in neighbourhoods having a population with fewer resources, areas often discussed in terms as ‘deprived’ or ‘excluded’, concepts that alludes to the phenomenon of segregation. Presence or visibility of key facilities manifest power situations and relations, and, may be seen as symbols of society at large and even extensions of society affecting tendencies of social exclusion and inclusion. It is argued that amenities, and what they represent, materialized through architecture, are important not only for those who use these facilities but also for others. These institutions are in a low-intense way continuously reminding of the larger society and signal coherence with such larger community.

    In this study we investigate how the location of schools performs as a result of spatial location in combination with spatial configuration, creating different degrees of accessibility and presence locally. More specifically, we investigate to what extent institutions for education are located centrally in the area, visible for both locals and non-locals, and to what extent they are situated at ‘front row seat’ from a configurative perspective. We draw from ideas discussed by Hillier (2009), Vaughan (2013), Legeby et al. (2015), and Peponis (2017).

    First, the most central paths and spaces are identified in the studied district, establishing the integration core. Then, the location of schools are analysed in relation to this. Apart from establishing the most central paths and how this structure relates to the schools, we add information of the size and content of the catchment area of each school, including distance between residential buildings and schools. This allows for a detailed mapping of variations in access to schools within the neighbourhood, and establish presence or absence of these institutions in the neighbourhood, argued to have implications both for pupils (and their families), as well as for others. Finally, income levels are superimposed to reveal to what extent there is diversity of different socio-economic groups within each specific catchment area.

    The results show that there are two different logics at work in the district of Gottsunda, having different social implications; preschools tend to be more deeply located in the structure, having more limited catchment areas but a strong relation to housing units, while compulsory schools are located in proximity of the integration core and thus more present in the neighbourhood at large. Moreover, the location of the schools in combination with the configurative properties is found to reproduce residential segregation patterns rather than creating interfaces between social groups. We argue that urban design and architecture could be more efficiently used when trying to create more equal living conditions and address social exclusion if we have higher awareness of the social implications of what is located at ‘front row seat’ in a neighbourhood.

  • Disputas: 2019-10-07 10:00 KTH, sal A124, plan 1, 100 44 Stockholm
    Lundgren, Marja
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur, Arkitekturteknik. White arkitekter AB.
    Performance in the Swedish Building Code: An Inquiry into the Consequences for Architectural Design of the Formulation and Assessment of Performance Requirements2019Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis investigates performance-based regulation in Sweden and its consequences for architectural design. In the last 50 years, there has been a transition from prescriptive to performance-based regulation, propelled by the drive to further innovation, productivity and competitiveness by expressing the functions expected of the buildings as performances. This thesis examines the promise of freedom in design and solution that this regulatory construction offers, considering two specific performance aspects of the Swedish building code: the requirements regarding energy performance in relation to user-comfort, and the requirement in terms of daylight in relation to health and hygiene. Each case investigates the implications of the performance-based system of regulation for the synesthetic and multidisciplinary process of design, focussing on how it affects the work of architects.This thesis also addresses the disciplinary knowledge necessary for assessing performance requirements, which in turn connects to the entry into building regulation of abstract natural science models quantifying societal goals in legislation, and to the disciplinary histories of the engineering and architectural professions.Speculating on ways forward that address the concerns that emerge from this analysis, the thesis turns to a historical example that dealt with a similar problem to evaluate its potential for developing current architectural practice. The dual nature of design, reaching into both expressional and technical concerns, has been the subject of research and eloquent discussion within the architectural concept of tectonics. The concluding section of this thesis raises questions about the architectural discourse in relation to tectonics. It suggests that there is work to be done to reconcile the division between architectural design and technical characteristics connected to building physics that permeates systems of building regulation in Sweden and more generally. The thesis suggests that if performance-based regulation is to offer freedom in architectural design, the architecture community needs to be much more involved in both the research and critique of performance requirements and of their formulation and assessment methods when addressing this.

  • Zakhoy, Solin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Safeen Butros, Diana
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Parametrisk Design2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I samband med digitaliseringens intåg har nya förbättrade BIM-verktyg börjat användas för att effektivisera konstruktörens arbete. Med hjälp av implementering av grafiska tredjepartsprogram kan BIM verktygen bidra med ökat funktionalitet. Ett exempel på ett sådant program är tredjepartsprogrammet Grasshopper kopplat till BIM-verktygen Tekla Structures som skapar parameterstyrning, vilket innebär att modellens data styrs och nås av de externa programmen. På Rambolls Bro- och Tunnelavdelning vill man idag, som många andra konsultföretag bli mer BIMorienterade. Dock saknas en uppskattning av den totala tidsbesparingen och nyttjande av tredjepartsprogrammen. Syftet med detta examensarbete har varit att komma fram till en slutsats som ger stöd i beslutsfattande kring vilka typer av projekt som parameterstyrda modeller kan vara lämpliga för. Genom uppbyggnad av ett automatiserat skript för en stödmur har denna studie visat kopplingen mellan programvarorna Microsoft Excel, Rhinoceros-Grasshopper och Tekla Structures. Med denna tillämpning har man lyckats skapa ett lätthanterligt användargränssnitt. Vidare har man jämfört det färdiga skriptet i Grasshopper med en modellering i Civil 3D där man har kommit fram till att man kan vinna tid på att ha ett optimalt skript. Man har även kunnat dra slutsatser under vilka förhållanden det lämpar sig att använda parametrisk modellering och automatisering som pekar mot tidiga skeden i projektering och standardkonstruktioner.

  • Sanna, Karemsijan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Kasabian, Maral
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    En granskning av IFC-exporter från Tekla Structures2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Idag tillämpas BIM (Building Information Modeling) som ett ledande verktyg inom byggprojektering och möjliggör lösningar som är hållbara och optimerade mellan olika discipliner för att effektivt hantera informationsflöden. Vid överföring av data mellan programvaror används ett neutralt filformat, IFC (Industry Foundation Classes). Detta filformat exporteras från 3Dmodelleringsprogrammet Tekla Structures. Syftet med detta examensarbete är att granska orsaken till saknad information vid IFC-export från Tekla Structures. Studien innefattar en fallstudie, komparativ studie samt intervjuer. I fallstudien studeras inställningarna för en IFC-export från en komplex modell i Tekla Structures. Den komparativa studien berör två samordningsprogram Solibri Model Checker och Navisworks Manage, som sedan ställs mot varandra. Det som undersöks är hur IFC-filer lämpar sig i samordningsprogrammen. Intervjuerna har legat till grund och har gett tydliga riktlinjer under arbetets gång. Resultatet av denna studie tyder på att orsakerna kring saknad information i IFC-filer är den mänskliga faktorn och bristande kunskaper av inställningarna i en IFC-export. Ytterligare resultat är jämförelsen mellan samordningsprogrammen som visar att båda är lämpade för IFC-formatet. Genom den komparativa studien har det visat att Solibri lämpar sig bättre för IFC-exporter från Tekla Structures. Med hänsyn till examensarbetets resultat är den mänskliga faktorn avgörande för informationsförluster. Den mänskliga faktorn utgör att det råder bristande kommunikation samt bristande kunskap om IFC-exporter.

  • Stanislawska, Cornelia
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Intermodala godstransporter i Sverige: En kunskapsöversikt av hinder och tekniska lösningar2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In 2018, the Swedish Government developed a new freight transport strategy. The strategyemphasizes that climate-friendly modes of transportation should be used to a greater extentfor freight transport. Intermodal transport, where unit-ready goods are transported with acombination of transportation modes, has been proposed as one of the solutions. As part of thework with the new strategy, the Government has commissioned the Swedish TransportAdministration to investigate what obstacles there are to intermodal transport, and toinvestigate whether there are any technical solutions or innovations that can increase the useof intermodality. The purpose and aim of this work have been to support the SwedishTransport Administration with their assignment from the Government by compiling thebarriers and technology of intermodality.By conducting a thorough examination of previous research and reports of intermodality,mainly railway and maritime transport, together with an in-depth interview with a Professor inthe subject, several different angles and views on the subject have been gathered.The results show that there are several areas in the industry where problems have beenidentified. Regulations and organizational structure, the limited area of competition andtransfer potential, the quality of the infrastructure and the location and costs of the terminalsare the main barriers to intermodality in Sweden today.It is possible to use technical solutions or other innovations to help minimizing one of theobstacles, the location of terminals and costs. These can for example be horizontaltranshipment technology, autonomous transhipment technology, IT systems and simulationtools or innovative network structure and location of terminals.Although there are plenty of ideas of new technology and solutions, few of these come intoproduction. One of the problems is the users/company’s uncertainty about investing inprojects that they do not know will be profitable. Standardized dimensions also present anobstacle to the technology which then must be adapted to current dimensions and strengthrequirements. There must also be a policy at international, national and local level with acommon goal that encourages the use of new technology.Most of the obstacles identified cannot be solved quickly and easily by introducing newtechnology. Instead, authorities and actors in the industry need to review their priorities andcommunicate with each other in order to come up with common solutions.

  • Andersson, Mats
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Mellin, David
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Genetic Algorithms: Comparing Evolution With and Without a Simulated Annealing-inspired Selection2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Genetic Algorithm (GA) is an interesting problem solving algorithm which takes inspiration from evolution in order to self-improve and reach good solutions to problems by reproduction and mutation. This thesis compares a GA with and without a Simulated Annealing (SA) inspired selection when it comes to solving three different instances of the Traveling Salesman Problem (TSP). SA was found to be able to help the GA reach better solutions, but the results also depended on other parameters within the GA itself.

  • Almgren, Love
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Holm Åström, Johan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Probabilistic modelling and attack simulations on AWS Connected Vehicle Solution: An Application of the Meta Attack Language2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This work is focused on investigating if the Meta Attack Language (MAL) can be used to create an integrating layer between two different applications of the MAL, and thus being able to model a new domain. In this case vehicleLang and awsLang were choosen as candidate applications of the MAL. While the domain chosen was to model the AWS Connected Vehicle Solution Infrastructure. This domain therefore modelled a service that is quickly becoming popular among car manufacturers. The two languages were successfully compiled into one language using the MAL, and also able to model a leak within AWS that could potentially lead to greater exposure of the infrastructure as a whole. On the other hand some limitations in the MAL compiler has lead to suggestions of how to improve it for better support of integration of different MAL applications.

  • Wallström, Andreas
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Omer, Mohammad-Ali
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Implementing Security Techniques to Lower the Probability of IoT-devices Getting Hacked2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    IoT security is something that is becoming more important with the exponential growing number of IoT devices. It is important to find methods that can make IoT devices more secure and are feasible to install and use. This paper investigates how effective the security features geographical IP based blocking (GeoIP) and a limit on the number of allowed sign-in attempts to a server (fail2ban) are at reducing the number of successful hacker attacks. By launching honeypots with and without these security features data was collected about the number of hacking attempts. The results shows that the GeoIP security feature can reduce attacks by roughly 93% and that fail2ban can reduce the attacks by 99%. Further work in this field is encouraged to create better GeoIP tools and to better understand the potential for these security techniques on a larger scale.

  • Björklund, Rickard
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Software Reuse in Game Development: Creating Building Blocks for Prototyping2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As games and the technologies used by them have become more advanced, the cost of producing games have increased. Today, the latest AAA titles are the results of hundreds or as many as thousands of people working full-time for years, and even developing a prototype requires a large investment. This project sets out to reduce that cost by looking at how reusable building blocks can be used in the prototyping process.

    During the project, seven interviews with game designers were conducted. The interviews found that building character controllers for the player was the most common activity and one of the more difficult tasks when prototyping a new game. As a result, a tool for creating character controllers was made.

    The tool builds the character controllers to work as state machines where actions in a state and transitions between states are editable through a visual programming language. The visual programming language uses nodes. These nodes work as reusable building blocks.

    The tool was evaluated by six game designers and four programmers who all thought the tool used a good approach for building and prototyping character controllers. The evaluation also showed that the building blocks, in the form of nodes in the tool, should be functionally small and general, like nodes for applying forces and accessing character data.

  • Niklasson, Johan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Hahr, Oskar
    Topology optimization for distributed consensus in multi-agent networks2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Distributed networks, meaning a network in which several agents work together unanimously to perform some task in order to reach goals has become a field with a wide range of applications. One such applications may exist in the form of drones with a purpose of observing and detecting forest fires.

    In such applications it can be of paramount importance to be able to agree over some opinions or values between the agents. This value could be something such as event detection or a general direction to fly in. However in such a network there might not exist a central hub and it would not be possible for all drones to communicate directly with each other. In order for such a network to be able to reach consensus or agreement, values have to be exchanged between the agents.

    This thesis focuses on a subset of this problem known as distributed averaging. In the thesis it is investigated how a networks ability to detect forest fires and communicate both efficiently and quickly can change when the number of agents are adjusted in the network.

    The results showed that, when operating in a fixed area, for a small network of drones the increasing effective energy cost per drone were higher, than that of a larger network. It was also discovered that the speed at which a network could reach an agreement was not necessarily affected by the size of the network. But as the field area being observed was increased, adverse effects were observed in terms of communication and event detection.

  • Dolfe, Rafael
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Matinzadeh, Keivan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Investigating Skin Cancer with Unsupervised Learning2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Skin cancer is one of the most commonly diagnosed cancers in the world. Diagnosis of skin cancer is commonly performed by analysing skin lesions on the patient’s body. Today’s medical diagnostics use a established set of labels for different types of skin lesions. Another way of categorising skin lesions could be to let a computer perform the analysis without any prior knowledge of the data, where the data is a data set of skin lesion images. This categorisation could then be compared to the already existing medical labels assigned to each image. This categorisation and comparison could provide insight into underlying structures of skin lesion data.

    To investigate this, three unsupervised learning algorithms; K-means, agglomerative clustering, and spectral clustering, have been used to produce cluster partitionings on a data set of skin lesion images. We found no clear cluster partitionings and no connection to the already existing medical labels. The highest scoring partitioning was produced by spectral clustering when the number of clusters was set to two. Further investigation into the structure of this partitioning revealed that one cluster contained essentially every image. Although relatively low, the score does indicate that the underlying structure may be best represented by a single cluster.

  • Björkman Nilsson, John
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Cervall, Jonatan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Drones without a master: Resource efficiency in consensus-reaching topologies2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this study we have compared five different heuristic algorithms for adding edges to existing graphs with the goal of improving convergence rate for reaching consensus. This while keeping the cost of adding edges, and thus sending more signals, in mind. Finding a suitable algorithm for this purpose would equate to monetary cost savings and inference speed in multi-agent networks. The study found that simulated annealing performed the best with regards to finding the best solution on multiple graphs, performing the best in average and time complexity of finding the solutions. However, it was not by a significant margin but alongside our own heuristic named degree difference, they could in conjunction find the optimal solution in every test and their collective complexity is still feasible. The study did not find any rule of thumb for adding edges, except that disregarding costs and only focusing on improving convergence rate worked well. Future work would be to take more factors into consideration to make the scenarios more realistic, such as avoiding single points of failure in a network.

  • Ariss, Joseph
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Rabat, Salim
    A comparison between a traditional PID controller and an Artificial Neural Network controller in manipulating a robotic arm2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Robotic and control industry implements different control technique to control the movement and the position of a robotic arm. PID controllers are the most used controllers in the robotics and control industry because of its simplicity and easy implementation. However, PIDs’ performance suffers under noisy environments. In this research, a controller based on Artificial Neural Networks (ANN) called the model reference controller is examined to replace traditional PID controllers to control the position of a robotic arm in a noisy environment. Simulations and implementations of both controllers were carried out in MATLAB. The training of the ANN was also done in MATLAB using the Supervised Learning (SL) model and Levenberg-Marquardt backpropagation algorithm. Results shows that the ANN implementation performs better than traditional PID controllers in noisy environments.

  • Karlsson, Charlotte
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Utvärdering av potential hos organiska restmaterial för avsättning i form av biokol2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Runtom på den svenska marknaden finns olika strömmar av restmaterial som idag ofta uppfattas som avfall. För att uppnå ett mer cirkulärt samhälle finns förhoppningen om att dessa restmaterial skulle kunna nyttjas i en ny applikation och anses som en resurs istället för ett avfall. Biokol, ett kolrikt material skapat genom pyrolys av biomassa, har potential att innebära en högvärdig avsättning för vissa av dessa restmaterial. För att kunna säkerställa kvaliteten på det producerade biokolet för avsedd användning, har en metod nyttjats som kopplar samman materialets egenskaper, biokolets egenskaper och funktioner och lämpliga applikationer. Utvecklingen av en sådan metod kan innebära ett sätt för potentiella tillverkare av biokol att hitta en ny avsättning för sitt restmaterial och säkra att kunderna får rätt produkt för avsedd applikation. En utvärdering av de potentiella ekonomiska och miljömässiga fördelar som en produkt i form av biokol kan bidra med har även genomförts.

    Efter en genomförd intervjustudie valdes ett restmaterial ut för fördjupad analys; finfraktionen från utsiktat flis av returträ. Idag hanteras flis av returträ huvudsakligen genom förbränning, men potentiella förändringar i hanteringen av detta material kan uppstå inom en snar framtid. Finfraktionen i materialet medför problem under förbränning både genom slitage och korrosion på utrustning och genom brandrisker vid lagring. På grund av denna problematik förutspås att en utsiktning av denna finfraktion, som kan utgöra upp emot 20% av materialet, kan bli aktuellt. En förändring av kraven från mottagande förbränningsanläggningar kan medföra att ett restmaterial snabbt uppkommer i stora volymer, ett restmaterial som saknar avsättning.

    Genom att undersöka egenskaperna hos denna returträ-finfraktion kunde uppskattningar göras gällande de egenskaper som det tillverkade biokolet skulle komma att få, vilka funktioner kolet kan fylla och vilka applikationer som skulle kunna vara passande. En koppling kunde därmed göras mellan restmaterialets inneboende egenskaper och de kvalitetskrav som ställs på olika användningsområden. Den egenskap hos materialet som medförde störst problematik var innehållet av tungmetaller, med ursprung ifrån tryckimpregnerat returträ eller de färger som använts vid behandling av materialet. För att kringgå problematiken kopplat till innehåll av metaller föreslogs en tillverkning genom flash-pyrolys där en stor del av ingående restmaterial omvandlas till pyrolysolja. Studier har visat att genom denna tillverkning kan en olja med lågt innehåll av metaller produceras genom att metallerna istället koncentreras i kolet. Detta innebär dock att kolet inte uppfyller de krav som ställs för att kallas biokol, men ger en stor fördel genom att metallerna binds starkt in i kolstrukturen och på så sätt blir mindre biotillgängliga. Genom pyrolys minskar också volymen av materialet som behöver hanteras.

    Den applikation som ansågs mest lämplig, för kolet producerat ifrån finfraktionen av returträ, var kolfilter vid rening av avloppsvatten, som ersättning för aktivt kol. Då metallerna är starkare bundna i kolet, jämfört med ingående biomassa, anses kolet fortsatt lämpligt som filtermaterial. Vid jämförelse av miljöpåverkan och energiåtgång vid tillverkning av de olika alternativen framgick det att kol ifrån returträ har en mindre klimatpåverkan gentemot aktivt kol, samtidigt som adsorptionskapaciteten av olika metaller inte skiljde sig åt markant. För de kunder som skulle köpa in denna produkt finns även en fördel i en minskad inköpskostnad då pris för kol producerat från biomassa är ungefär hälften av priset för aktivt kol.

    Svårigheter som fortsatt måste hanteras är dock sluthanteringen av produkten efter användning, experimentella studier som bekräftar egenskaper och adsorptionskapacitet, samt en mer djupgående ekonomisk utvärdering för att säkerställa att potentiella tillverkare kan finna en lönsamhet i denna hantering av sitt restmaterial.

  • Abdelwahab, Kemal
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Farah Mohamed, Abdirizag
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Spricktillväxt i stålkonstruktioner på grund av utmattning2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Stålbroars approximativa livslängd bestäms av stålets utmattningshållfasthet, då utmattning är en av de främsta anledningarna till att livslängden begränsas. I Sverige existerar ett antal broar som närmar sig slutet av sin livslängd, samtidigt som behovet för kapacitet och kraven på broarna ökar. Flertalet av dessa broar är i behov av upprustning. Däremot är det inte möjligt ur vare sig ett ekonomiskt- eller miljöperspektiv att byta ut alla broar, och därför behöver de broar som är mest kritiska prioriteras. Vid utmattningsdimensionering av stålbroar beaktas hela spänningsvidden, oavsett om spänningarna är i drag eller tryck. En spricka propagerar endast vid dragspänningar, vilket innebär att tryck- spänningar egentligen inte bör vägas in i samband med dimensionering. Detta innebär att en del stålbroar skulle kunna ha en längre livslängd än vad den traditionella dimensioneringen ger. Spänningsintensitetsfaktorn 𝐾 används inom brottmekaniken för att förutspå spänningsintensiteten i närheten av sprickspetsen, och appliceras till linjärelastiska material. Det finita elementprogrammet Abaqus användes när brodetaljen modellerades och analyserades. Brodetaljen representerar en balk med en påsvetsad anslutningsplåt, som utsätts för trafiklasten på en bro och en temperaturlast för att simulera egenspänningar. Detaljen representerar problematiken med utmattning i stålkonstruktionsdelar. Motivet för denna studie är att inga sprickor har hittats under inspektioner av liknande detaljer, det till trots att en del stålbroar teoretiskt sett förbrukat sin livslängd. Studien genomfördes med en mer avancerad modell än vad som vanligtvis skapas för bedömning av utmattning, med syftet att modellera verkligheten mer korrekt. Resultaten visar hur egenspänningarna bidrar till dragspänningar, vilket leder till sprickpropagering i modellen. Vid spricklängden 9,5 mm övergår spänningarna från drag till tryck, och då upphör spricktillväxten. Resultaten visar även att utmattningssprickor kan växa i stålkonstruktionsdelar som i huvudsak utsätts för nominella tryckspänningar, ifall höga egenspänningar uppstår vid anslutningsplåten.

  • Abdi Yussuf, Yusuf
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    Jalal Ibrahim, Zand
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggteknik och design.
    FRP:s användning inom brokonstruktioner2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I dagsläget är de flesta broar i Sverige tillverkade med betong eller stål. Dessa broar är många gånger förknippade med stora kostnader som ofta beror på underhåll och reparation. FRP, som står för Fiber Reinforced Polymer, är ett relativt nytt material i bärande stommar men är ett väl etablerat material i förstärkningssammanhang. I Europa och i synnerhet Nederländerna finns det flertal broar byggda i FRP. Men på grund av brist på normer och regelverk att luta sig emot sker det sällan någon form av brokonstruktion med FRP i Sverige. Detta examensarbete syftar till att undersöka befintliga normer och studera hur materialet FRP används vid förstärkning och konstruktion av broar. Vidare syftar även arbetet till att undersöka egenskaperna hos FRP som byggmaterial och jämföra det med konventionella material som stål och betong. FRP, också benämnd fiberkomposit, är ett kompositmaterial som kan sammanställas på flera olika sätt. Genom olika material som kombineras och olika tillverkningsprocesser som används kan man på så sätt ge individuell utformning till materialet för dess användning. Fördelarna med FRP är många, men i allmänhet har det god styrka, god beständighet samtidigt som det har en låg vikt. Detta resulterar i att inom brokonstruktion så ger det strukturen en minskad egenvikt, vilket i sin tur underlättar en mängd olika saker. Detta arbete visar på att FRP-material har fördelaktiga egenskaper och kan i vissa situationer vara mer gynnsamt att använda än stål eller betong. Dock som tidigare påpekat saknas det specifika Eurokoder för detta material. Däremot är vi säkra på att introduktionen av en ny Eurokod samt med uppmuntran från myndigheter kommer användningen av FRP inom brokonstruktion utan tvekan öka. 

  • Lindahl, Amanda
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Industry 4.0 as a Tool for Improvement in a Global Food-Supply-Chain: A Study on how Industry 4.0 can be Implemented in a Global Bakery Group2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Industry 4.0 is at the moment one of the most talked-about topics amongst industry companies. Management teams of discuss the area as something they want to implement, but since it is an ongoing industrial revolution it cannot be implemented straight away. This study is looking into the subject of Industry 4.0 and the identification of nine different technology drivers that a manufacturing company can use as tools in a production environment. However, what is less known is how the tools can be applied to a global company and its different cultures. Because even though Industry 4.0 is about decentralization and giving responsibility to every co-worker, they need to work with a common framework, thus standardization. A company that has started to look into Industry 4.0 is Lantmännen Unibake, who is a global bakery group. Therefore, they serve as the case company in this exploratory study where the goal is to conduct a pre-study that gives them, and the food industry, information and guidelines on how Industry 4.0 applies to their industry. Hence, what improvements it can lead to, what tools that will be suitable, and what the prerequisites for a successful Industry 4.0- transformation will be. The method to answer the research question starts with conducting a comprehensive literature study, followed by several interviews around Europe, and ending in an analysis of the current state with help from the literature framework.

    The analysis has ended in a conclusion that there is no single or easy answer to the questions since food industries might vary a lot from one to another. Although, in this case, the answer would be that six out of nine tools would be applicable in a global food-supply-chain, some needing more preparatory work than others. By implementing these tools, companies will see more engaged employees that are prone to take autonomous decisions, more accurate production planning, proactive rather than reactive working ways, fewer defects, and higher customer satisfaction. Regarding the prerequisites for transformation, the answer depends on what tools that are used. But what all cases have in common is that there is a need for aware and engaged employees. Everyone will have to be in on the change, understanding why and how, and what benefits that will come out of it. For future studies, it is suggested to look into how maturity models can be applied to these kinds of issues smoothly. The existing maturity models for Industry 4.0 are very complicated and difficult to apply; thus, they would need some development. Another area would be a cost model of the different tools, as well as a comparison of the tools and food regulations.

  • Ameen, Ahamed
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Optimization of annealing parameters for SANDVIK 13C26 and 20C strip steels: By MODDE analysis and modified JMAK method2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The process optimization of continuous annealing furnace, RHF 125, for recrystallization annealing of two steel grades, Sandvik 13C26 and Sandvik 20C has been carried out. To recreate the continuous annealing process carried out in the roller hearth furnace in the industry, samples with different cold reduction rates were chosen from ongoing production lines. An experimental heat treatment model was chosen by the ‘Design of Experiments’ approach from MODDE (from U-Metrics). The annealing temperature was chosen below the austenitization temperature for both steel grades and soaking time of 30 seconds to 240 seconds were chosen. Microscopic estimation of fraction recrystallized was performed with the help of Electron Back Scattered Diffraction, accompanied by mechanical testing methods to measure the hardness and yield strength of the steel strips. The experimental output was used to create a model to correlate between the different cold reduction rates and annealing parameters to achieve a higher degree of recrystallization along with desirable mechanical properties. Also, a modified Johnson-Mehl-Avrami-Kolomogrov model, based on hardness values, to determine the transformation kinetics by tracking the progress of recrystallization was developed. The model was verified with EBSD measurements for Sandvik 13C26 strip steels. For 20C, inhomogeneous recrystallization was observed, thus limiting the model’s adaptability to steels which exhibit homogeneous recrystallization behavior and negligible change in precipitation and/or coarsening of secondary phases.

  • Disputas: 2019-10-04 10:00 Ångdomen, Stockholm
    Honeth, Nicholas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Distributed Topology Inference for Power System Applications: Algorithms and architectures utilising industry standards2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The electrical transmission and distribution system is undergoing unprecedented changes to meet the need for a carbon emission-free global energy system. An expected increase in the portion of end-user energy use in the form of electricity and need to integrate renewable energy sources into the power grid on a large scale require major changes in how power grids are operated and controlled.The systems and methods used to monitor, control and protect the power grid have developed in a context where the net power flow could be assumed to originate at large centralised power stations and be transmitted, distributed and delivered to end-users. The operation and control systems still largely follow a centralised and hierarchical structure with a control centre extending a multitude of connections out to automation systems over the geographical span of the grid. With the large-scale integration of distributed generation in the power system and the interconnection of grid infrastructures to facilitate inter-area trade of electricity, many of the premises on which traditional control systems were developed are currently changing. As more distributed generation capacity is integrated into parts of the power grid, efficient methods for determination of the electrical connectivity, the grid topology, become essential components for the development of all other control systems. The systems on which these methods are implemented must interoperate seamlessly with existing and future infrastructure. One effort to address this is an internationally coordinated standardisation process for power systems management and information exchange. The resulting standards, for example, IEC 61850 and IEC 61970, provide a framework for the development of new architectures and methods with a high level of interoperability whilst remaining applicable to the wide variety of equipment and applications that will be required. This thesis aims to test the hypothesis that distributing the application logic closer to the substation automation systems directly connected to the electrical process, provides a suitable architecture which can acquire system-wide knowledge of grid topologies without the assistance of a central entity. To achieve this, three research objectives are identified; proposing of novel control system architectures, utilising state-of-the-art structured data and equipment in substation automation systems and finally to develop a distributed topology inference algorithm utilising minimum prior knowledge of the grid it is acting within.The results firstly demonstrate the use of multi-agent systems as a distributed control and monitoring architecture. Secondly, the result demonstrates the application of relevant standardised IEC 61850 data models and interfaces for data exchange, and how they can be integrated into such architectures. Thirdly, the development of work on a multi-agent systems architecture and algorithm for distributed topology analysis of power grids is described and a formal description of the topology inference algorithm is given. Finally, a validation for the algorithm using a reference power grid model is presented.

  • Wärnberg, Emil
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST). Dept.of Neuroscience,Karolinska Institutet, Sweden.
    Kumar, Arvind
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Perturbing low dimensional activity manifolds in spiking neuronal networks2019Inngår i: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 15, nr 5, artikkel-id e1007074Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several recent studies have shown that neural activity in vivo tends to be constrained to a low-dimensional manifold. Such activity does not arise in simulated neural networks with homogeneous connectivity and it has been suggested that it is indicative of some other connectivity pattern in neuronal networks. In particular, this connectivity pattern appears to be constraining learning so that only neural activity patterns falling within the intrinsic manifold can be learned and elicited. Here, we use three different models of spiking neural networks (echo-state networks, the Neural Engineering Framework and Efficient Coding) to demonstrate how the intrinsic manifold can be made a direct consequence of the circuit connectivity. Using this relationship between the circuit connectivity and the intrinsic manifold, we show that learning of patterns outside the intrinsic manifold corresponds to much larger changes in synaptic weights than learning of patterns within the intrinsic manifold. Assuming larger changes to synaptic weights requires extensive learning, this observation provides an explanation of why learning is easier when it does not require the neural activity to leave its intrinsic manifold.

  • Rigas, Konstantinos
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Thermal Physical Properties of Söderberg Electrode Material2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Söderberg electrodes take part in the production of ferroalloys, copper, nickel, platinum, and calcium carbide. They are involved in a continuous and with low costs operation. The study of such electrodes is essential, since research and new findings will provide us with vital information regarding the operation of such furnaces leading to a more efficient production. Therefore, the study of Söderberg electrodes materials characteristics is of great importance. The current work refers to the thermal properties of Söderberg electrode paste by focusing on the thermal conductivity coefficient from room temperature up to 800 °C with the Transient Plane Source (TPS) method applied to an electrode paste material with softening point at 65°C. Another electrode paste with higher softening point at 90 °C and an already baked material are studied to some extent. The study gives significant results for the thermal conductivity coefficient for all the investigated cases. Results indicate variation of coefficients regarding the phase evolved during heating at different temperatures. In principle, thermal conductivity of the green paste with low softening point decreases until 400°C and increases after the baking point which is found in between 400-500°C. A few measurements for the green paste with higher softening point indicate the same trend. For the case of the fully baked electrode, thermal conductivity seems to keep an increasing trend according to temperature increase. On the two last mentioned materials, more experimental work will be conducted in future.