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  • Public defence: 2018-05-30 13:00 Ka-Sal C (Sal Sven-Olof Öhrvik), Kista
    Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Opportunities and challenges of mobile payment services: The perspective of service providers2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

     Mobile payments are transforming the payments industry. These services open up the opportunity for non-banking actors to enter the market. In order to embrace this challenge, banks, traditional payments market players, are forced to launch mobile payments. However, in Europe and most developed economies, a big number of launched services get terminated soon after their introduction in the market. Hence, the ability of different actors to act locally calls for additional research.

    The main objective of this thesis is to broaden knowledge and understanding about the ways mobile payment service providers address the opportunities and challenges of mobile payment services. In order to investigate this problem, this research (i) explores factors stimulating and hindering the introduction of mobile payments using perspectives of different types of service providers (i.e., banks, independent providers, direct operator billing providers, retailers, and public transport companies) and (ii) seeks to explain the importance of these factors for each type of provider.

    The primary data collected using interview method. More than 40 industry representatives in six countries were contacted. The Service, Technology, Organisation, and Finance (STOF) model was used as a theoretical research framework. This is a business modelling framework that specifies a set of critical design issues that have to  be considered within each model’s domain.

    Research findings highlight that the organisation domain is the key domain, which  affects all other domains and has an impact on the general viability of the business model. A comparison of the approaches used by different service providers to address each of the critical design issues helped to identify the factors that are most important within each domain. These factors stimulate or hinder development of a viable business model within each category of service providers.

    This research contributes to a better understanding of challenges and success factors associated with the design of business models for new mobile services and uses the lens of the STOF model. The contributions to the academic research on mobile payments are: (i) collection and analysis of a rich empirical data set on mobile payment services implemented in six Northern European countries, (ii) discussion of a bigger picture by connecting research findings to the context of the existing payment system, (iii) extension  of knowledge on business models for mobile ticketing, and (iv) extension of knowledge on the value of mobile ticketing services in the business-to-business (B2B) context.

  • Nilsson, Tomas
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Kommer du att välja natur ellerteknik?: om vad som styr elevers val av gymnasieprogram2018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study was motivated by both observations in upper secondary school classes in the

    Swedish programs natural science programme (NA) and technology programme (TE), where

    unexpected and unexplained differences between the groups of students were seen, and by

    differences found in statistics covering these two programs. The gender distribution is the

    most pronounced difference, where this is about equal in NA but with a significant male overrepresentation

    in TE, but there are differences also in cultural and educational backgrounds

    among the two groups of students. It is obvious that these differences do not occur during

    education in upper secondary school but is established at the point when the students choose

    their program. The purpose of this study is therefore to investigate the causes and rationale

    for why students choose as they do, among these two programs. The scientific questions

    formed are 'On what are the students choice of NA/TE based?', 'What attitude do students

    have toward the programs when they choose?' and 'Are there any differences in how students

    at the two programs make and motivate their decisions?'.

    These questions are investigated through an interview study where some students who had

    just started at their upper secondary studies were asked to recount their experience from

    choosing program. The interviews were conducted during the first two weeks after the start of

    the semester and included five students from NA and six students from TE. The students were

    interviewed individually, each for about half an hour, according to a semi-structured scheme.

    The interviews were split into two parts, where the first focused on their choice and their

    selected program and the second brought up the program which was not selected. The

    interviews were analyzed according to several scientific theories, in the areas of processes and

    motifs, comfort zones and choice theory.

    The results of the interviews indicate that the students primarily choose programs based on

    the subjects they are most interested in, where the students at NA prefer biology and the

    students at TE prefer technology. However, the study also shows that there are differences

    between the personalities of the students who choose the two programs. The study shows that,

    in general, NA students are determined in their choice, they only make a limited consideration

    of other options and are considered to be socially stronger. The students at TE are more

    analytical in their selection and have thought their choices through thoroughly but were

    considered to be less socially competent.

  • Aboode, Adam
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Anomaly Detection in Time Series Data Based on Holt-Winters Method2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today's world the amount of collected data increases every day, this is a trend which is likely to continue. At the same time the potential value of the data does also increase due to the constant development and improvement of hardware and software. However, in order to gain insights, make decisions or train accurate machine learning models we want to ensure that the data we collect is of good quality. There are many definitions of data quality, in this thesis we focus on the accuracy aspect.

    One method which can be used to ensure accurate data is to monitor for and alert on anomalies. In this thesis we therefore suggest a method which, based on historic values, is able to detect anomalies in time series as new values arrive. The method consists of two parts, forecasting the next value in the time series using Holt-Winters method and comparing the residual to an estimated Gaussian distribution.

    The suggested method is evaluated in two steps. First, we evaluate the forecast accuracy for Holt-Winters method using different input sizes. In the second step we evaluate the performance of the anomaly detector when using different methods to estimate the variance of the distribution of the residuals. The results indicate that the suggested method works well most of the time for detection of point anomalies in seasonal and trending time series data. The thesis also discusses some potential next steps which are likely to further improve the performance of this method.

  • Düllmann Vasques Pereira, Joana Lena
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Decarbonizing Public Bus Transport – a case study on Curitiba, Brazil2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Air pollution is becoming a major issue in cities across the world, its common cause being the use of fossil fuel combustion engines in both private and collective transport modes. However, alternative technologies, such as biofuels, hybrid and battery electric vehicles, are on the rise.

    The objective of this thesis is to assess the optimal system’s configuration – a combination of electric traction and the use of biofuels – in a sub-group of Curitiba’s public bus network through the application of two optimisation models – least energy consumption and least cost. Based on these models, total energy, cost and greenhouse gas (GHG) emissions can be calculated for different scenarios to identify the advantages of switching to a low-carbon system. Furthermore, these models can be used by planners and decision makers as a starting point in defining the path towards a cleaner transport system.

    The results from the energy optimisation indicate that electrification is key in reducing total energy consumption, as this technology is by far the most energy efficient. A 12% reduction could be achieved, when compared to the current scenario (only using diesel B7), and CO2 emissions could be cut by 74%.

    The cost optimisation shows that electrification is not yet cost competitive compared to other biofuels (biodiesel, bioethanol and biogas), as biodiesel is the only technology selected by the model due to its overall lower cost. Nonetheless, if electricity costs are reduced, which can be achieved, for example, through a reduction or abolition of taxes, electrification becomes an attractive alternative to biofuels. Under these conditions (40% lower electricity price), energy consumption is reduced by 5% and GHG emissions are cut down to 30%.

    Political will and strategies to decrease the cost of vehicles turn out to be essential in supporting electrification in public transport. Furthermore, adaptations in the time schedules and the organisation of the main transport hubs are required to accommodate battery electric buses.  The number of fast charging stations is usually on a par with the number of bus routes to be electrified. Cost synergies achieved by sharing the cost of a charger among electrified routes with a common start/end stop are crucial to secure the attractiveness of e-mobility. This underlines the importance of analysing infrastructure needs in public transport networks holistically.

  • Mohsenchian, Asal
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Energy follow-up of the technology building in New Karolinska Solna Hospital (NKS)2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For the past few years the importance of energy efficiency and sustainability has beenin more focus due to increased CO2 emissions, energy prices and global warming. The EuropeanUnion aims to reduce greenhouse gas emissions by 20% and increase the renewable energy shareof total energy consumption to 20% by the end of 2020. These requirements will be achieved bydifferent means where investing in energy efficient buildings, transport and products is one of thepriorities. (European Commission, 2015).Requirements on energy and environment certification and the energy performance directives haveresulted in closer attention of property owners to the importance of the energy consumption inbuildings. According to the last edition of Boverket's Building Regulations; BBR 22, at designstage, all new buildings must be proven to meet the energy performance requirements of BBR. Averification of the energy performance based on the measurements of energy consumption mustbe done within 24 months after the building is completed (Boverket, BFS 2015:3).In this master thesis project an energy follow-up of the technology building U3 in NKS (NewKarolinska Solna Hospital) will be carried out. This will be done by comparing the results fromsimulations at the design stage with the results of real energy consumption of the building from 31March 2014 to 31 March 2015.NKS has high energy and environmental requirements and it is supposed to be one of the firstuniversity hospitals in the world certified by LEED (Leadership in Energy and EnvironmentalDesign). Technology building or U3 is located in the northern part of the hospital and it is the heartof the energy distribution and production of the hospital. It provides hospital with power, heating,cooling and backup power. Technology building was completed in May 2014 and since then CoorService Management is responsible for the operation of the building.This thesis has been done in cooperation with the company Skanska Healthcare (SHC). The goalof the project was to find out, at a very early stage, the difference between measured energy useof the building with the estimated values during the design stage.For analysis, the measured data for heating, cooling and electricity consumption of the buildingfrom 31 March 2014 to 31 March 2015 was used. The total specific energy use of the technologybuilding, U3, obtained by measurements is 60 kWh per m2 Atemp per year, which can becompared to the result from simulation which is 73 kWh per m2 Atemp per year.The accuracy of this comparison is impacted by limitations in simulation tools, such as inputdata limitations, internal tool limitations, or user caused limitations, and the uncertainty inmeasured data which are usually not well organized.

  • Isacsson, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Snow layer mapping by remote sensing from Unmanned Aerial Vehicles: A mixed method study of sensor applications for research in Arctic and Alpine environments2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis presented in this report was conducted to identify which sensors and methods could be applicable in the mapping of snow stocks in the Arctic region. To make that assessment, several different methods have been used. Interviews with experts in relevant areas were held to make an initial survey of what information might be the basis for the subsequent step, a quantitative regression analysis based on information collected through systematic review of the use of platforms and sensors in mapping by remote sensing. In this analysis, relevant correlation areas were identified, which could then be further analyzed in a state of the art compilation of relevant publications to provide a fair understanding of what methods are available and what their respective strengths and weaknesses are. Finally, a flight was carried out with a view to practically assessing what quality can be achieved in snow mapping with readily available consumer products. The results point out that snow mapping exploration with drones is a promising complement to manual measurements. Recommendations for further studies include component-specific surveys, platform design and market mapping.

  • Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Primary data collection: Approaches of service providers towards mobile payments2018Report (Other academic)
    Abstract [en]

    Mobile payments are new services enabled by evolution of information and communication technologies. These services can be provided by different types of actors both banks and non-banks. The understanding of capabilities and limitations of different service providers to act in local markets requires further understanding. Implemented research seeks to extend knowledge in this area. I have implemented research focused on approaches used by different types of service providers including banks, independent providers, operator billing providers, retailers, and public transport companies in six Northern European countries.

    Exploratory part of the research aims to address the following research question: What factors stimulate and hinder the introduction of mobile payments? The main objective of this report is to present primary data collected during the research through interviews with contacted companies.

    The collected primary data is classified and organised using the STOF (Service, Technology, Organisation, and Finance) model. Evidence is presented in tables. This primary data is further used for explanatory study. At the same time, this data can be used by other researchers studying the same area. The collected data is reach in facts and presents the overview of different strategies. 

  • Public defence: 2018-05-09 10:00 F3, Stockholm
    Mussa, Abdilbari Shifa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. KTH The Royal Institute of Technology.
    Durability Aspects of Fast Charging, Mechanical Constraint, and Inhomogeneity in Lithium-Ion Batteries2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of lithium-ion batteries with higher energy and power density, better safety, and lower cost has significantly contributed to the increased market share of electric vehicles (EVs) in the last decade. However, the expectations of end-users of EVs still require a continuous quest for better performance. One important end-user expectation is the ability of the battery to be charged rapidly, but the durability of lithium-ion batteries could be affected by the fast charging. Hence, detailed investigations are required to understand the extent and mechanism of the degradation for an optimized battery usage and material development.   

    In order to meet the high energy and power required in EVs, multiple large-format cells are connected in series and in parallel. Such a condition leads to an uneven distribution of temperature, pressure, and current in a cell or among cells that may cause locally inhomogeneous ageing and accelerate the global battery ageing. This thesis investigates the effects of charging rate, charging protocol, and external compression on battery durability. The impacts of inhomogeneities induced by cell design constraint, and uneven compression and temperature distributions are also addressed. The studies are based LiNi1/3Mn1/3Co1/3O2/graphite cells. Cell housing for a controlled pressure and temperature application was developed. Electrochemical and material characterization techniques were used in the investigation.

    The results show that fast charging at a rate equivalent to full charging in 20 minutes (3C rate) or less accelerates battery ageing. The ageing rate is less sensitive to charging rate in a longer charging time, i.e. at 2C and below, where it is determined more by factors such as the extent of full charging. In all cases, the capacity loss is limited by the cyclable lithium loss. External compression of a battery in an optimum range reduces ageing, but compression above or below the optimum range accelerates ageing. Lithium-ion batteries age non-uniformly. Cycling induces an increase in the impedance at the outer radius of curvature of a prismatic cell jellyroll, associated with a loss of contact between the current collector and the electrode coating. An unfavorable current distribution induced by uneven temperature distribution can accelerate battery ageing. 

  • Dhomé, Ulysse
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Further development and performance evaluation of the autonomous sailing boat Maribot Vane2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper describes the ongoing development of Maribot Vane, an autonomous sailing vessel at the Maritime Robotics Laboratory of KTH, the Royal Institute of Technology, Stockholm. There is an ac-celerating need for ocean sensing where autonomous vehicles can play a key role in assisting scientists with environmental monitoring and collecting oceanographic data. The purpose of Maribot Vane is to offer a sus-tainable alternative for these autonomous missions by using wind and an energy efficient self-steering mecha-nism. The rig is composed of a free-rotating wing fitted with a coupled control surface. A completely novel wind vane self-steering solution has been developed and is being evaluated. A key point in the development of the vessel is robustness, with a goal of being able to sail in open seas for long period of times. The paper discusses some key concepts, the development method and presents initial results of the new systems.

  • Gros-Borot, Maeva
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Modelling a foil load spectrum using recorded data on a racing foiling yacht2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The intent of this Master Thesis is to investigate foil loadings on racing foiling yacht based on recorded data. This work was done by means of recorded microstrains along the foil and other recorded data such as boat speed and fly height. Composite foils are developed by the company GSea Design using an in-house software called Sofia which uses Fluid Structure Interaction (FSI) to design deformable appendages. In this Master Thesis, a tool that enables to get a numerical model of the foil adjusted to the recorded strains at a given time was designed. For that, recorded strains along the foil were first evaluated and post-processed to calculate the corresponding bending moments along the foil. Then an optimization loop based on the Sofia software was implemented. This loop automatically adjusts the numerical model of the foil to the recorded bending moments and computes the global Up and Side forces (vertical and anti-

    leeway forces, respectively) applied on the foil that contribute to the boat’s equilibrium. This approach was set up and tested during this Master Thesis. It enabled to show that building a representative load case in terms of global Up and Side forces with the corresponding numerical model using recorded data at a given time was possible. This work also highlighted some remaining constraints such as long calculation times to get an adjusted model automatically on recorded data. It implies that future work on data processing or optimisation improvements will constitute the next steps developed by GSea Design to be able to set up a foil design in terms of lifetime.

  • De la Gardie, Fredrik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Road unevenness relation to road safety - a vehicle dynamics study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this Master thesis in Vehicle Engineering, is to study the road unevenness relation to road safety. The long term objective is to be able to prioritize which road section that is in the need of repair and maintenance prior to other road sections.

    This study focus on how close to an acceptable safety limit the vehicle is handled when it is run over different road surfaces. This applies to straight road sections as well as cornering, where the road surface is uneven and bumps/pits occurs. No driver behaviour or random actions are analysed but these aspects will be included in the overall discussion.

    The method to analyse this is through computer simulation. From a Volvo S40 a computerised vehicle model has been developed in Matlab and the effect of different road unevenness has been implemented and analysed. Forces that are generated by the unevenness of the road are compared with the normal forces that a driver needs to correct the course based on the friction between tire and road surface. On this basis, a margin to the risk of losing the grip can be estimated. In this way it can be interpreted how a road section contributes more or less, compared to another section, to whether the vehicle is closer to a safe limit from a vehicle dynamic perspective.

    The vehicle model has been analysed at a speed of 70 km/h with the simplification that the irregularities can be described by sinusoidal shapes. For larger bumps or dips in the road the results show that both front and rear tires can absorb side forces so that stability can be achieved. If the grip would deteriorate due to gravel, ice, etc. there is a risk that the vehicle loses steering control and/or cord leading to damage of the tyre and consequently an accident will occur. For the analysed road unevenness in the form of bumps and pits the tires do not have any ability to absorb required side forces during an avoidance manoeuvre when travelling over the road due to the tyre model used.

    It is therefore important that a section with varying unevenness are analysed to determine a maximum speed so that the control of the vehicle during the whole distance can be maintained regardless of whether control needs to be done in connection with the unevenness.

    A recommendation of future work in this area is to develop this model to make it more robust and to update the input data with relevant data for one today representative car and to carry out a more detailed full-scale modelling with also lateral simulations. If the model was verified with measured normal forces for a test car that has travelled over various bumps and pits, this would also be valuable to confirm the validity of the model. There would also be improvements if available road profile is implemented in the analysis so that realistic examples can be analysed for better real-world analysis.

  • Bengtsson, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    ThermoacousticInstabilities in a Gas Turbine Combustor2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stationary gas turbines are widely used today for power generation and mechanical drive applications. The introduction of new regulations on emissions in the last decades have led to extensive development and new technologies used within modern gas turbines. The majority of the gas turbines sold today have a so called DLE (Dry Low Emission) combustion system that mainly operates in the leanpremixed combustion regime. The lean-premixed regime is characterized by low emission capabilities but are more likely to exhibit stability issues compared to traditional non-premixed combustion systems.

    Thermoacoustic instabilities are a highly unwanted phenomena characterized by an interaction between an acoustic eld and a combustion process. This interaction may lead to self-sustained large amplitude oscillations which can cause severe structural damage to the gas turbine if it couples with a structural mode. However, since a coupled phenomena, prediction of thermoacoustic stability is a complex topic still under research.

    In this work, the mechanisms responsible for thermoacoustic instabilities are described and a 1- dimensional stability modelling approach is applied to the Siemens SGT-750 combustion system. The complete combustor is modelled by so called acoustic two-port elements in which a 1-dimensional ame model is incorporated. The simulations is done using a generalized network code developed by Siemens. The SGT-750 shows today excellent stability and combustion performance but a deeper knowledge in the thermoacoustic behaviour is highly valued for future development.

    In addition, measurement data from an engine test is evaluated, post-processed and compared with the results from the 1-dimensional network model. The results are found to be in good agreement and the thermoacoustic response of the SGT-750 is found to be dominated by both global modes including all cans as well as local modes within the individual cans.

  • Bréus, Elsa
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Finite elements modelling of rotor flapping mass2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the frame of increasing flight safety, finite element models are developed to computethe stresses in critical parts. The results obtained often complete the ones derived from fullscale experimental tests and analytical estimations. A finite element model is particularlyuseful to simulate many different flight configurations that can not be tested experimentally.This paper presents the different stages in the development of a finite element model ofa rotor flapping mass. On a helicopter the flapping mass makes the connection betweenblades and rotor hub. This study particularly focuses on the estimation of the fatiguelimit of a composite component. This component, called roving winding, is particularlycritical as it sustains most of the loads applied on the flapping mass. Getting an accuraterepresentation of the stress distribution in the roving was the main objective. The resultsderived from the model presented here were compared to experimental ones to ensure itsaccuracy. The confidence in the model obtained makes possible its use to evaluate theimpact of some material change or geometry modifications. The model also permitted toevaluate the impact of some productions defects on a composite part.

  • Garnell, Emil
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Designing, building and validating a test rig to measure two-port data of small fans2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There is a great need in the industry for measurement methods to characterize acoustic sources in ducts. One way to obtain a complete description of a source is to measure 2-port data, comprising of the source scattering matrix and the source vector. The resulting model can then be used to predict the source properties, e.g., radiated sound power, in the plane wave range for all installation conditions. Methods to measure the two-port model have been developed over the last few decades and can today be efficiently used for industrial purposes. The present thesis presents the whole process of designing, building, and validating a 2-port rig to measure high speed small fans, as well as an example of how to use the data to predict the noise emission of a product. All rig elements have been designed after a literature review and an analysis of the physical principles governing the behavior of the rig. Guidelines on microphone spacing, loudspeaker mounting, rig terminations and overall rig dimensions are given. The theory behind the measurement method of the active two-port in a duct is presented. 

    Additionally, a number of different post-processing methods are evaluated with respect to the properties of the experimental setup used i.e. the number of available microphones, the magnitude of the reflection coefficient at the rig terminations and the type of test object measured. The standard method that is most widely used nowadays is shown to become singular when the reflection coefficients at the rig terminations are high. A new post-processing method is suggested, and tested against the standard one. It is shown to behave better in highly reflective cases.

  • Jaipal, Prithviraj
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Hydraulic hybrids2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Conventional IC Engine powertrain layouts in vehicles tend to consume considerable amounts of fuel and generate emissions that are harmful to the environment. Newer technologies have enabled the development of sustainable vehicle layout designs that favor a reduction in the exhaust emissions and energy consumption without compromising the vehicle’s performance. Hybrid vehicles and electric vehicles are the torch bearers for this development. Although electric vehicles feature high performance at lower emissions, they are generally limited by their range and high battery costs. Development of countries to equip for this electrification is another important factor here as with the development of more electric vehicles comes the problems associated with charging, like charging stations, charge scheduling (from power grid because of the high toll), etc. Hybrid electric vehicles are energy efficient and reduce the emissions considerably but their costs are substantially higher. Along with the higher efficiency generated by the electric machines, the possibility of regenerating braking energy reduces the energy consumption and increases the energy efficiency of the conventional layouts. Hydraulic hybrids in the recent years have gained recognition for their advantages and are known for being the cheaper alternative for hybridizing heavy vehicles. The ability of storing regenerative braking energy in this fluid form allows for higher cyclic efficiency when compared to that of the electrical means of storing energy. This thesis focuses on the design and modeling of the hydraulic hybrids using MATLAB/SIMULINK® to construct models depicting the use of the vehicles under the selected drive cycles. Regenerative braking has been one of prime focus for improving the range and minimising the energy consumption of the vehicle along with high operational efficiencies of the operating components. The thesis takes into account two cases, one with the case of a medium duty vehicle with a conventional  IC Engine layout and the other with the case of electric forklifts. The two cases are compared with their hydraulic hybrid layouts along the lines of energy consumption, operational efficiencies and range. Through the design of these simulations, a comparative analysis of the hydraulic hybrid to the electric hybrid is provided for the case of the medium duty vehicle and the benefits of having an electric hydraulic hybrid layout designed for the electric forklift applications are studied.

  • Koponen, Henrik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Investigation of a New Test Method to Perform a Vibration Test on Alternators2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis work was performed in the Scania RECT group. The purpose of this study was to investigate a new test method and to examine if it was possible to perform a vibration test on two alternators at the same time where one would act as a motor and the other as a conventional alternator. That all electric machines can be run both as a motor and a generator was nothing new. But the question was whether it was possible to put a load on the motor with enough good results to perform a vibration test. Among other things, in order to verify that subcontractors conform to Scania’s life length requirements, these types of vibration tests are routinely performed. Previous tests have shown that there have been some problems to perform a vibration test during operation. This due to low belt tension and unwanted resonances in the system. After thorough analysis of different control systems a controller to try to get the generator to rotate was purchased. First tests showed that it was possible to operate the alternator as an electric motor. Thereafter the new electric motor was paired with a similar alternator via a belt to start loading the original alternator. Two alternator types were investigated, one that worked significantly better in terms of testability than the other and the decision was taken to only use the better during the final vibration test. To the final test a completely new test rig was constructed to run new converted alternators in the future. Also, a fixture compatible with the bottom plate where the shaker test is performed was designed for future tests of alternators. Final vibration test resulted in several interruptions where the tested alternator broke down several times at the given PSD level and the final test could not be completed. However, it could be concluded that the new test method worked very well and can be used for future vibration tests of alternators.

  • Pau, Michael Kristian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Model-Based Output-Only Identication of Coupled Thermoacoustic Modes2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A model-based output-only method for identifying from time-series data the parameters that determine the dynamics of a stochastically forced thermoacoustic oscillator has previously been implemented in the case of a single standing thermoacoustic mode. This thesis presents an extension of the method in question to two coupled standing modes at the same frequency.

    An appropriate thermoacoustic model, as used in the previous works, is presented wherein the dynamics and probability distributions of the coupled thermoacoustic oscillator are described by a Langevin equation and its corresponding Fokker-Planck equation. The system identification method consists of fitting the analytical drift and diffusion coefficients to values that are estimated numerically by extrapolating the finite-time Kramers-Moyal coefficients to the short-time limit. This method is

    shown to be functional for the case of coupled standing modes but areas of improvement remain, in particular concerning computational efficiency.

    An alternative method of system identification based on iterative finite element solutions of the adjoint Fokker-Planck equation is shown to be unsuitable for coupled standing modes without significant further optimisation in the finite element step.

    Finally, an exploratory investigation into the system identification of coupled rotating modes at the same frequency is conducted. It is found that the transition probabilities in this case display unusual behavior that is unknown at this stage to be physically correct or due to error.

  • Shekhar, Rudrendu
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Stability Analysis during Active Tire Excitation for Friction Estimation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Road accidents have been a persistent cause of death worldwide, and claim millions of lives everyyear. Recent developments in the active safety systems like Electronic Stability Control (ESC) havehelped in reducing these numbers quite signicantly over the years. However, a major challenge forthese systems is to know the friction coecient between the tire and the road, as this value limits theamount of force the tires can generate. Knowledge of the coecient of friction can be used to adaptthe driving style, thereby avoiding interventions by stability control at the limit, making vehiclessafer. However, it is a major challenge within the automotive industry to estimate the coecientof friction accurately, and with sucient availability, as that requires high levels of tire utilization,such that the tire is forced to reach the non-linear range of operation. Such events are very rarein everyday driving, and requires a system induced active excitation of the tires. One such methodthat has been proposed earlier, to carry out an active tire excitation, is by using a simultaneouspropulsive and brake force on front and the rear the axles. However, applying an equal magnitudeof propulsive and brake force results in a force neutral situation at the vehicle level, which forcesthe velocity to be constant, overriding driver acceleration requests. Thus, an active tire excitationmethod was proposed by Volvo Cars, which is able to apply an unequal propulsive and brake forceto the front and the rear axle, such that the driver's acceleration demand can be met, during frictionestimation. However, such an excitation can be dangerous to carry out, if it leads to instability ofthe vehicle.Several methods have been developed to analyze and quantify stability of a vehicle, but detailedanalysis about the stability under forced excitation, for friction estimation, is very rare. This thesiswork investigates the lateral stability of a vehicle undergoing an active tire excitation for frictionestimation. The objective is to understand which vehicle and tire models can be used to quantifythe lateral stability of a vehicle under forced excitation, and how phase portrait methods can beused to develop a stability monitor that is able to indicate the lateral stability of the vehicle undera forced excitation.The results of using a stability monitor during active tire excitation clearly show that it is able toindicate when the vehicle becomes unstable and looses control. It also shows that for slow speedsteady-state maneuvers and straight line maneuvers, the stability monitor does not indicate instability.A comparison between phase portrait based and conventional side-slip based stability monitorsshow the eectiveness and generality of the phase portrait based monitor, which is able to detectinstability earlier than the conventional side-slip based method.

  • Xie, Yuan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Investigation on Road Noise Transmission through Steering System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An investigation on noise transmission through the steering gear system is focused on the area of vehicle NVH (Noise Vibration and Harshness). From previous investigations it is well known that noise transmission through the steering system sometimes has a significant influence referring to tire road noise. In these cases, the interface force between steering gear and vehicle subframe is usually of interest during early stages of vehicle development. The target of the current work is to validate an approach based on a method, commonly known as the “Blocked force method” for noise and vibration testing, and check if it is possible to estimate the interface forces based on this method. This method became popular for mechanical testing in the middle 1900s [1] [2] [3], because of its easy applicability. The basic idea is to fix the component on a rigid plate and measure the interface force at the coupling points with force transducers inserted in between. It has a considerable potential in practical use, because if the blocked force could provide a good estimation for the interface force in noise transmission, it enables an efficient measurement of critical NVH behaviors without having to resort to the complete vehicle.However intuitively, the blocked force data could not be used directly. As a result, a coupled system equation is used for the coupling of the steering gear and the car body. Both the inertance of car body and steering system are taken into account, and thus introduces a compensation for the difference between vehicle and test bench. The method is validated against the transfer function measured on the full vehicle as the reference and compare this with the result calculated with the measured “Blocked force” data. Siemens Test.Lab is used for data acquisition and first data processing. Matlab is used for data post processing. Matrix symmetrization and singular value truncation is used to deal with the ill-conditioned data of steering gear inertance. A hybrid model with Finite Element data is proposed. Two test conditions are investigated: one set is with rigid coupling and the other is decoupled with rubber.

  • Dessle, Filip
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Harvesting and utilizing beach cast on Gotland: A study of the benefits, challenges and opportunities of turning a waste into a resource2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Accumulation of beach cast biomass on coastal zones around Gotland is an increasing problem that reduce the recreational value of beaches and cause environmental degradation of coastal environments. Beach cast was once regularly harvested on Gotland, as it was considered a valued biofertilizer, but as it seized to be used in combination with the eutrophication of the Baltic sea, beach cast accumulation has increased in scale. The use of beach cast as a resource for bioenergy and agriculture does not only provide important services that can replace the use of greenhouse gases and finite resources but can also mitigate eutrophication and increase the quality of coastal zones as nutrients are retrieved from the water. Macroalgae and seaweeds are hyperaccumulators of heavy metals which pose a challenge for the utilization of beach cast as a fertilizer. Especially cadmium, a heavy metal that is harmful for human consumption, is strictly regulated and limits the amount of beach cast that can be used for agriculture.

    This thesis has analysed the potential benefit of beach cast harvesting and three potential utilization strategies of beach cast; fertilizer to food crops, fertilizer to fast growing energy forest (Salix) and biogas production with digestate utilization. The result indicate that all strategies are possible and viable utilization strategies under certain conditions. Because of the complex and site specific factors that affect beach cast utilization, adapting strategies depending on the conditions and needs of the local coastal zones is required. Cadmium uptake is affected by a range of factors that can be controlled so that beach cast can provide nutrients and improve soil structure without contaminating the soil. Especially promising is the prospect of fertilizing Salix with beach cast as the cadmium absorption and growth rate of Salix enables large amounts of beach cast to be spread without risk for it accumulating in the soil. The cadmium contained within the Salix can later be removed from the environment entirely as it is collected from the ash when Salix is converted to bioenergy. Recent studies also indicate that food crops can be safely fertilized with beach cast without cadmium being transferred if specific crops are chosen. Cadmium uptake to crops can also be limited if specific beach cast with low cadmium content are used and if the beach cast is pre-composted with other substrates. Both for Salix and food crops its instead legal restraints on cadmium spreading that limits the use of beach cast. When abiding by the set cadmium restrictions, beach cast can only marginally supply the macronutrient requirement of the average food crop on Gotland. Biogas production and digestate utilization from beach cast provides many environmental benefits as clean renewable energy is generated that can replace fossil fuels and the nutrients contained in the digestate can be spread on arable land. From the conducted energy balance of the system on Gotland it was found that beach cast has theoretically good conditions to ferment beach cast. However, beach cast isn’t practically viable on Gotland because the substrate can’t compete financially with other available substrates and it requires costly pre-treatments. Regardless of which beach cast utilization strategy chosen, harvesting is concluded to have a positive effect on mitigating coastal eutrophication and beach and water quality. Although it cannot on its own mitigate a net nutrient loading to coastal zones in Gotland, harvesting easily available beach cast can reduce the nutrient loading to coastal zones on Gotland with up to 27 % and 4,5 % phosphorus and nitrogen respectively.

  • Public defence: 2018-05-16 13:00 E2
    Xylia, Maria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Towards electrified public bus transport: The case of Stockholm2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses the challenge of road transport electrification using a systems approach for the particular context of Stockholm’s public transport system. The objective is to identify the benefits of large-scale bus electrification on energy efficiency and greenhouse gas emissions, as well as the cost and planning considerations required for achieving such a shift. Quantitative and qualitative methods are deployed for answering the research questions, including the development and use of an optimisation model, survey research, and interviews. 

    The results of the optimisation model developed for this thesis show that an optimal system configuration is obtained with a combination of electricity and biodiesel. The high energy efficiency of electric buses would lead to a significant reduction of energy consumption in Stockholm, even if not all bus routes in the network are electrified. Although larger battery capacities could support the electrification of more bus routes, this does not necessarily lead to lower environmental impact. In any case, electricity from renewable sources should be used to maximise emission reductions. 

    The results also show that the annual costs necessary to invest in electric buses can be balanced by lower fuel costs. An effective utilisation of the charging infrastructure is of high priority in order to justify the costs of the required investments. The model results confirm the benefits of creating a dense initial network of charging stations in the inner city’s public transport hubs, which would facilitate the electrification of multiple routes and high infrastructure utilisation at lower costs. 

    The survey and interviews with stakeholders indicate that multiple issues affect the choice of charging technology, not just costs. Compatibility, reliability, bus dwell time, as well as weather conditions and visual impact are some of the additional aspects taken into account. The introduction of electricity tax exemption for electric buses, the expansion of the electric bus premium to include private stakeholders, as well as the expansion of infrastructure investment subsidy programmes are among the policy instruments suggested for assisting a faster introduction of electric buses into Stockholm’s public transport system. 

    Although the focus is on Stockholm, the conclusions of this work can be applicable to other cities in Sweden and around the world, which also face the challenge of making public transport a more sustainable option.

  • Andersson, Erika
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Kundutbildning från tre infallsvinklar: En fokusgruppstudie om hur utmaningar skulle kunna reduceras2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study is conducted as an assignment from Saab in Järfälla, Sweden. Saab wanted help to reduce the challenges in the customer training since the instructors had expressed they needed help to improve it. The purpose of this study is to map the challenging situations that an instructor at Saab can experience during the customer training, and analyse how the challenges could be reduced. The main focus is put on organisational culture, pedagogic competence, and specialist knowledge.

    The theoretical background describes the following theories: adult teaching, competence, and organisational culture. The development of the competence is discussed and the importance of how to use the right competence is stated. The organisational culture is discussed and what an organisation can do in order to strengthen the culture is presented. Theories for adult teaching are also presented.

    A qualitative approach, in the form of focus group interviews, are used to collect data. Four focus group interviews are analysed using thematic analysis where the different themes and codes are found using the theory.

    The results indicate that the different challenges that the instructors are facing in the customer training are linked and that they influence the organisation as a whole. An example of what Saab could do in order to reduce the challenges in the customer training is presented and discussed based on relevant theories. The things that Saab may do to reduce the challenges, according to this study, are: improve the communication, work as a team and try to create a strong organisational culture.

  • Firmansyah, Husni
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Power and Methanol Production from Biomass Combined With Solar and Wind Energy: Analysis and Comparison2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to investigate the feasibility of an integrated system consisting of biomass-based power generation built-in with carbon capture technology combined with a water electrolysis unit operated by solar cells and wind turbines to produce fuel through the methanol synthesis process. The configurations are examined both technically and economically to determine their feasibility, and subjected to sensitivity analysis to determine their economic viability and optimum performance. Each integrated system has the same subsystems configuration including electrical power generation, electrolysis unit and solar/wind renewable electricity input.

    Three main system configuration variations for carbon extraction from biomass feedstock have been evaluated, based on pre-CCS in the form of integrated biomass gasification combined cycle (IGCC), in-situ CCS represented by Oxy-fuel combustion concept, and post-CCS via exhaust gas treatment, assuming the same access to woodchip feedstock.Two important substances for methanol production are carbon dioxide coming from biomass and hydrogen supplied by water electrolysis based on intermittent renewable energy sources. Coil evaporation system to provide CO2 separation would perform differently in each system; oxy-fuel, pre-CCS and post-CCS alternatives. Meanwhile, H2 supply is provided by the electrolysis process using water supply and electricity produced from solar and wind power. In addition, the effect of location and uncertainty factors is discussed among the sensitivity studies.

    The technical analysis shows that with 5 ton/hour of biomass feed, each system configuration could produce up to 5.8 t/h of methanol. On the other hand, the economic analysis shows LCOE of Oxy-fuel and the IGCC approaches the lowest possible to 0.086 €/kWh and 0.1060 respectively; while for the gasification process 689 €/ton methanol is produced. The interest rate risk can deviate from the energy cost up to 16% higher when the interest rate is increased from 8% to 9%.

  • Geerolf, Laurent
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    The Biogas Sector Development: Current and future trends in Western and Northern Europe2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The following study attempts to provide a comparative analysis of the biogas production activities in 15 countries in Western and Northern Europe. The goal is, for each country, to gather all the available information about the present status of the biogas sector and then to evaluate the possible trends for future development in terms of main biogas production pathways, valorization, volumes, market dynamics, etc.First, a review of the current biogas production, including feedstock types and valuation pathways, is carried on. Then, national supporting schemes are reviewed and assessed in order to estimate their future impact on the production capacity. An estimate of the production volumes in year 2022 is attempted, based on the extrapolation of current support schemes and national objectives. The prognosis towards year 2022 is further subjected to sensitivity analysis with the breakdown per valorization method and feedstock input types, as well as with the probable variability of financial support schemes. The results of the study are summarized and discussed based on comparisons with other forecasts and feedstock availability projections.The results show that the current situation in each country is very heterogeneous in terms of technologies, volumes, maturity, potential growth and valorization aspects. However, the future holds a promise of a more straightforward trendline: agricultural residues should be used much more as feedstock (in co-digestion with other inputs) and biogas upgrade to biomethane should increase a lot, mainly for injection in existing gas grids. However, market dynamics are and will remain very different from one country to another, because of diverging support schemes set on a national scale.

  • Tepe, Julius
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Development of a Data Transformation Method for a Customized Stent usingAdditive Manufacturing2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Conventionally manufactured stents are available in uniform sizes and straight forms. These standard products are not suitable for all patients and research indicates that this is the reason for migration of stents in the vessel, and tubular structure in general, after deployment. The occurrence of migration makes readmission into hospital and the removal of the deployed stent necessary. This thesis develops a method which results in patient-customized stents which can be manufactured through additive manufacturing. These individualized stents intent to offer the same advantages of conventional stents while mitigating the disadvantages. The work’s core part is thedesign of a stent based on the geometric information through a medical scan. It converts the relevant areas from the medical scan data which is in the DICOM format to the STL file format. After cleaning and further processing, the shape will be the base for the design process of a stent using CAD software. Additionally, it also gives insight into the subjacent technologies such as medical scanning, additive manufacturing, choice of material and necessary further processing steps. A process chain from scanning, data transformation, 3D printing and post processing is described.The developed method delivers a reliable model and results in a fully individualized stent. In the current stage, it involves manual work since the representation of data in the steps is different. Further suggestions for steps to automate the process and an estimation of economic efficiency is given.

  • Wang, Chen
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Connectivity, Security and Integrationfor Cloud Manufacturing2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis project aims to connect the industrial robot to the Cloud platform, and evaluate the connectivity and security. To realize better connectivity, security and integration, a modified Cloud Manufacturing System (CRS) architecture is proposed, which is characterized by high modularity, standardization and composability. The architecture’s specific applications in private, public and hybrid cloud are discussed as well. Then, one system architecture with detailed software composition is designed for Cloud Robotics.According to the proposed system architecture, possible security threat sources and corresponding solutions are presented.During the project, Universal Robot 5 (UR5) is utilized as a practical robot instance to develop a communication routine between KTH Cloud and robots. An Application Program Interface (API) written by Python for Universal Robots and the server is established. The API consists of two modularized part, Gateway Agent and Application Package. The Gateway Agent realizes the connection between the Universal Robot 5 (UR5) and the cloud, while theApplication Package can be customized according to specific application and requirements. In this project, three main functions are developed in the Application Package, including data acquisition, data visualization and remote control. Besides, to evaluate connectivity and stability, private robotics cloud system and public robotics cloud system are simulated with KTH Cloud. The hybrid robotics cloud system is discussed as well. Through the results of case studies, the connectivity and integration of Cloud Manufacturing System are verified.

  • Gillberg, Linus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Sandberg, Christoffer
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Developing design guidelines for load carrying sheet metal components with regards to manufacturing method2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Load carrying brackets in the engine room of Scania's busses are almost exclusively manufactured through bending of sheet metal. It is believed that pressing, rather than bending, could result in lighter components. Lighter components mean less weight for the bus to transport and could, for example, result in allowing additional passengers on the bus.The problem definition included producing guidelines regarding the two manufacturing methods of sheet metal: bending and pressing. The guidelines were designed to aid, mainly novice, design engineers in early stages of component development. Existing components were FEM-analysed and redesigned to investigate the potential weight reduction for using pressing rather than bending. Lastly, on the topic of weight reduction, the potential of using carbon fibre reinforced polymer for load carrying components, such as brackets, was evaluated. The information for the guidelines and the evaluation of carbon fibre reinforced polymers were gathered through a series of study visits and a literary review.The guidelines were presented as a document, comprised of general considerations and rules of thumb. They are to be stored as a living document, continuously complemented and updated. The hope is to reduce the amount of unnecessary feedback from suppliers, and help designing cost-efficient components. The result from the modelling showed that weight reduction was possible by redesigning the investigated parts for pressing rather than bending. It was concluded that the most prominent weight reduction was achieved for components where removal of a limiting weld was successful. Further investigations should be conducted on a wider variety of parts to make the results more reliable. As for the carbon fibre reinforced polymers, the investigation indicates that a mere substitution of material is not cost-efficient for several reasons. To successfully implement use of carbon fibre reinforced polymers, larger and innovative solutions that utilises all the favourable properties of the material is required. Further studies should hence be initiated, with the focus of combining multiple purpose designs.

  • Public defence: 2018-05-15 13:00 Kollegiesalen, Stockholm
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar receiver development for gas-turbine based solar dish systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Small-scale concentrating solar power plants such as micro gas-turbine based solar dish systems have the potential to harness solar energy in an effective way and supply electricity to customers in remote areas. In such systems, the solar receiver transfers the power of concentrated solar radiation to the working fluid of the power conversion cycle. It is one of the key components as it needs to operate at high temperatures to ensure a high power cycle efficiency and under high flux densities to ensure a high receiver efficiency. In order to address these challenges and to ensure efficient and reliable operation innovative designs are needed.

    This research work focuses on the complete development of a novel solar receiver applying a new systematic design and analysis methodology. Therefore, a comprehensive receiver design and experimental evaluation process were developed and implemented. The design process includes the identification of technical specifications and requirements, the development of receiver design tools of different investigation levels coupled with multi-objective optimization tools, the evaluation of scaling effects between tests in the KTH high-flux solar simulator and the full-scale solar dish system. As a result of the design process a representative final receiver was established with material temperatures and stresses below critical limits while respecting the design specification.

    The experimental evaluation includes the enhancement of the KTH high-flux solar simulator to provide stable and reliable operating conditions, the precise characterization of the radiative boundary conditions, the design of a receiver test bed recreating the operating behavior of a gas-turbine, and the final receiver testing for multiple operating points. It was shown that the prototype reaches an efficiency of 69.3% for an air outlet temperature of 800°C and a mass flow of 29.5 g/s. For a larger mass flow of 38.4 g/s a receiver efficiency of 84.8% was achieved with an air outlet temperature of 749°C.

    The measurement results obtained were then used for a multi-point validation of the receiver design tools, resulting in a high level of confidence in the accuracy of the tools. The validated models were then harnessed to calculate the performance of a full-scale solar receiver integrated into the OMSoP solar dish system. It was shown that a solar receiver can be designed, which delivers air at 800°C with a receiver efficiency of 82.2%.

    Finally, the economic potential of micro gas-turbine based solar systems was investigated and it was shown that they are ideally suited for small-scale stand-alone and off-grid applications.

    The results of the receiver development highlight the feasibility of using volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems and no major hurdles were found.

  • Li, Xin
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Design and Implementation of Shop Floor Management Information System at BOSCH Rexroth AB2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis is conducted as a conclusion of Master of Science degree in Production

    Engineering and Management at KTH Royal Institute of Technology. The focus of this thesis

    work is to make the work more convenient and improve production efficiency by building a

    management information system (MIS) thus replacing manual and decentralized information

    management mode on the shop floor. With the use of the computers in the office and tablets

    beside the machine of each work center on the shop floor, personnel can have access to the

    necessary information easily and quickly.

     

    This management information system is built according to the actual production situation and

    needs in Bosch Rexroth AB in Mellansel. First, research on the production process and the

    management mode in the factory is conducted. Then, the form and the architecture of the

    system are decided. After thorough understanding and comparison, web application form and

    currently widely used Browser/Server (B/S) architecture are adopted. Finally, during the

    detailed design and system implementation process, databases and functional modules are

    developed. Microsoft Access is chosen as the database implementation. Microsoft Visual

    Studio.NET combined with C# language and IIS (Internet Information Service) is chosen as

    the application development tool. When conducting the user trial test on the shop floor,

    functions of this application system well meet the requirements, and associates can easily and

    quickly access the information. This application system can speed up the information flow in

    production, realizing more scientific, standardized and efficient management, which ultimately promotes the production and management of the enterprise.

     

    This management information system realizes the following functions in a digitized way: 1.

    system security management: user registration, log in and permission settings; 2. drawings

    viewing; 3. instructions viewing; 4. maintenance recording and checking; 5. deviation reporting and processing; 6. process confirmation recording and checking.

  • Laguna Serrano, Sergio
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Machining System Measurement and Modelling2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Machine tools need to be tested to check they behave correctly while machining. A bigger

    production (capacity), improving the accuracy in final products (quality) or reducing

    costs are some of the main goals. Reducing the maintenance of the machines, their nonproductive time and a higher quality of the final parts, have a strong influence in the costs.

    Even machines built to the same specification present different properties and behaviours,

    which leads into a reduction of the flexibility when it comes to move operations among

    them. This study is focused on the measurement and modelling of four machine tools

    (M1, M2, M3 and M4), with same specifications, from the static point of view. Methods

    used to measure all these properties are the circular tests under loaded conditions, with

    the device Loaded Double Ball Bar (LDBB), which measures positional accuracy and

    static stiffness. Different pressures (0.5, 1, 3, 5, 6, 7 bar) and locations for the LDBB have

    been used.

     

    After the tests were performed, all the machines shown good properties with the detail of

    M4, which had a lower stiffness than the other three ones due to its table attachments.

  • Wallentin, Markus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Lundin, Felix
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Unlocking Customer Segments Using Hardware Accessories2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report aims to describe the process for the master thesis within product development done by the authors during the spring of 2017 at KTH and iZettle, Stockholm. iZettle is financial technology company founded in Stockholm in 2010. In 2011 they released their first card reader terminal which, in combination with a mobile application, allowed small businesses to receive payments by card.

     

    The background for the project is that iZettle has identified customer segments that are not fully explored or satisfied by their current products. The card reader is today formed in a universal way that fits many different customer segments, but there is a lack of specialization that would benefit or unlock certain segments.

     

    The goal of the project was to identify segments that could benefit from a hardware accessory

    and to develop a solution/product to any of these problems.

     

    The development process implemented a user-centered approach and was carried out in three

    main phases, starting with a research phase focusing on understanding the problems by

    observing and interviewing potential users. This was followed by a concept development phase to diverge and explored a variety of possible solutions. The last phase, final concept

    development, converged into one concept that was further developed. The development phases made use of methodologies such as brainstorming, morphological matrix, sketching, CADmodelling and high- and low-fidelity prototyping.

     

    Three scenarios; taxi, food truck and counter, were found to have most potential benefits from an accessory combined with also being feasible for concept development within the scope of the project. Later in the process, the three scenarios were narrowed down to focus on the taxi

    scenario also due to the potential array of options, feasibility of a hardware solution as well as

    the market potential.

     

    The final concept is called the iZettle Dock Lite and is meant to fulfill the needs of a taxi driver by providing a mount that charges the reader and gives it a professional appearance in the car. An additional mounting device is the mounting stands that allows for placing the holder on a table or attach it to a wall, opening up for other use cases, such as food truck or restaurant.

  • Jonsson, Alexander
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Husell, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Design of an oral surgery simulator: Human-centered design study and implementation on a surgerysimulator2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The company Forsslund Systems has developed a simulator for oral surgery training.

    The simulator, named Kobra, uses detailed virtual models of surgical situations, spatial

    haptics and a co-located stereoscopic display to provide an environment in which students

    can practice surgical techniques. Four years after the introduction of the Kobra a need was

    recognized for a new hardware design that satisfies the customers expectations on visual

    appearance and hardware refinement and that aims to improve the experience for the end

    users. This report describes the design development process of the new enclosure, that

    had a focus on human-centered design, brand management and small-scale manufacturing.

    Inspired by findings from a comprehensive user study, conducted at a teaching hospital

    in Riga and relevant literature, as well as the results of prototyping and testing, the new

    design of the Kobra aims to improve the usability and market attractiveness of the product

    offering. This while being tailored to utilize the manufacturing technologies available to a

    small-scale in-house or out-sourced production team. A full-scale functioning prototype of

    the concept was built in-house, using the proposed means of manufacture, demonstrating

    a design that is close to ready for production.

  • Lang, Adam
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Fröderberg, Andreas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    An introductary view into Simultaneous LocalizationAnd Mapping2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years autonomous vehicles have gained attention as being the potential future for the automotive industry. A central part of an autonomous vehicle is the way that the vehicle locates itself relative to the surrounding environment. This localization can be efficiently performed simultaneously as building a map of the environment, a process called Simultaneous Localization And Mapping or SLAM. In this thesis, the basic algorithms that lay the foundation for the current state of the art of SLAM, and their refinements are studied with the goal of procuring a comprehensive list. The secondary goal is to create a simulation platform for assessing the performance of different algorithms.

     

    The thesis is commissioned by automotive consultancy AVL that will use the results to build their knowledge base within the autonomous field. Each algorithm that is mentioned has been looked at from a historical, mathematical and application perspective. This has resulted in a literature study containing thirteen algorithms and a table containing a categorization for easy and quick comparison. Categories of SLAM algorithms are identified to be map type, complexity, hypothesis and basic algorithm. Among the basic algorithms, the classic Kalman Filter and Particle filters have been found, along with modern Maximum a Posteriori algorithms. Furthermore, EKF and fastSLAM have been simulated in

    a Matlab environment for comparison. A development and simulation platform has also been developed in software frameworks Gazebo and ROS. This platform ensures modularity where algorithms can be exchanged and simulations can be run simultaneously as a real life implementation. The results  from the simulations show that the simulation in Gazebo can produce similar results as the traditional simulations in Matlab.

     

    It is difficult to know exactly which algorithms that are used in commercial applications. Using the information from the literature review, a discussion is made regarding which algorithms may be suitable for real life usage. The conclusion is that most likely, combinations of several algorithms are used in order to leverage the benefits from each, as well as mitigate weaknesses.

  • Krehl, Valentin
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    PLASTIC ADDITIVE MANUFACTURING AND ITS POTENTIAL EFFECTS ON A SUPPLY CHAIN: A case study concerning selection of beneficial parts for additive manufacturing through utilizing a methodological part evaluation framework2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Recently additive manufacturing (AM) is rapidly growing and evolving due to the advancements made in speed, quality, resolution and performance. Consequently, AM is starting to become, beyond prototyping, increasingly important for the manufacturing of end-use parts. Several successful case studies are reported and companies are starting to investigate in the opportunities of using AM for production processes and supply chain integrations.

     

    The purpose of this research is to evaluate the potential of using AM for manufacturing plastic end-use parts in a supply chain. Different AM technologies for plastic manufacturing are described and the main advantages and challenges are identified. Based on the company’s plastic part scope, a methodical framework for assessing parts regarding their AM suitability is established, in order to research the potential benefits of an AM implementation. The framework contains a methodical preselection and scoring process utilizing a top-down approach and an analytical hierarchical process (AHP), followed by a technical and economic assessment of the promising parts. In the research, only the existing design is taken into account: the same part, designed for conventional manufacturing technologies, is manufactured by AM without changes in geometry. Both cases, in-house manufacturing and purchasing from a service provider, were investigated with the employment of a cost model for FDM technology and a request for quotation from a general AM service provider. Both cases are compared to each other and the current conventional manufacturing technology.

     

    It was found that, currently, utilizing an AM service provider is more beneficial for the company, due to the low number of parts that could be currently produced with AM. Hereby the lead time for AM profitable parts could be significantly reduced. Using AM, a centralized production with one AM service supplier is clearly seen as the preferable supply chain configuration in the case of the company.

     

    The research provides guidance for the evaluation of part suitability concerning AM production of end-use plastic parts and contributes to the research concerning AM implementation in a supply chain in general and the aim of the company to acquire valuable AM knowhow in particular.

  • de Maio, Pasquale
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Optimization analysis of secondlifebatteries integration in fastchargersfor electric vehicles inSpain2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project investigates the viability of using reconditioned batteries, which have lost part of their original

    capacity while powering electric vehicles (EVs), to minimize the expenses of fast-charging infrastructures

    under the three charging scenarios where fast-charging mode is likely to be needed the most. The analysis

    is conducted for the Spanish scenario and considers the retail electricity tariff that best suits the requirements of a FCS. The economic analysis is performed on an annual basis and is tackled with an optimization algorithm, formulated as a mixed-integer linear programming problem and run on MATLAB. The expected lifetime of the ESS, being made of reused automotive cells, is estimated with a semi-empirical approach, using an iterative process and implemented in MATLAB. A sensitivity analysis is conducted on three input parameters that were identified to have a considerable impact on the system design and performance.

     

    Overall, results show that with current figures energy storage integration in FCSs is viable as it effectively

    reduces the infrastructure expenses in all scenarios. Peak-shaving is identified as the main source of cost

    savings while demand shifting is not effective at all. The latter is further discussed in the sensitivity analysis

    and some considerations are elaborated. The most profitable scenario for storage integration is the case of

    a fast-charger located in a urban environment while, surprisingly, the lowest cost savings are obtained in the highway case. The sensitivity analysis illustrates the impact and effects that electricity prices and specific cost of both the power converter and the second-life batteries produce on the optimal system design. Moreover, charging demand profiles are deeply analyzed and their main implications highlighted.

  • Ghiandelli, Marco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Development and implementation of small-scale biogas balloon biodigester in Bali, Indonesia2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Indonesia, due to its abundant resource of organic waste and a climate characterized by elevated and constant temperatures, is perfectly suited for anaerobic degradation and biogas production without applying expensive technologies. A huge number of household-level fixed-dome biodigesters installed in the last years in Indonesia have manifested problems such as costs, complex logistics, a bad follow-up strategy, the poor quality of the material and lack of farmers’ knowledge to operate and maintain the system. For this reason, a local company started to develop a prototype of a household balloon biodigester technology as an alternative to the common system, as a solution for the identified problems. Starting from a deep understanding of the issues shown by the prototype pilot test, a literature review of the anaerobic degradation process and similar technologies applied in developing countries was conducted, and the balloon biodigester was improved and a final product implemented. A second pilot test was carried out to assess the technical and economic feasibility of the technology. Its results showed that, compared with the prototype, the developed balloon design led to an increased time to carry out the installation steps due to the excavation process, but a reduced time to complete the operational activities and higher stability of the balloon. Moreover, the system provided almost the same output as the fixed-dome digester, achieving biogas to cook for almost three hours per day with no weight system required to achieve a sufficient pressure to cook. The biogas production was considerably faster than the first prototype, due to the sunlight irradiation. The material used for the bag, PVC 550, appeared sturdy and elastic, therefore offering an effective solution for the balloon digester technology. However, the technology should be tested for a longer period of time to ensure that no problem occurs in the material and in the anaerobic degradation process. Additionally, the economic assessment showed that, with a final cost of 637 dollars, the developed technology is not advantageous for the farmers as a substitute for LPG for cooking and more expensive than a fixed-dome digester. This is due to the expenses that cover the installation and the cost of the material. However, if part of the biogas could be used to cover the electricity needs for lightning, the NPV could slightly increase. The sensitivity analysis showed that at least the investment cost should be reduced by 20% to 500 dollars or the LPG price would need to increase by 80%, reaching 0.86 dollars per kg to make the system profitable for the farmers.

  • Lindahl, Christoffer
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Nilsson, Mattias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Modularity of a heater simulator and implementation in a prototype HIL-system2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis is about a modular low budget prototype hardware-in-the-loop system for testing diesel heaters. A modular plant model of the heater has been developed using model-based development in Simulink. The model has been derived mathematically from tests and empirical investigations. C-code was generated from the plant model and implemented in a microcontroller. The microcontroller simulates the model and sends the data values to different sensor emulators so that the electrical control unit is tricked into thinking it is connected to a real heater.

     

    The modularity is implemented in both software and hardware of the HILsystem. The plant model is modular by using different subsystems for the different parts of the heater. The hardware was also designed to be modular, in the form of ”fake” sensors that can be changed and also in the form of the different loads that represent the actuators, such as fan, in the heater. These loads can be changed is size depending on what is needed.

     

    An important aspect was to have the HIL-rig as low budget as possible. The tests show that the HIL-rig is suffering from bad resolution on the temperature during higher temperatures. This is due to the fact that the digital potentiometer used had a fairly low resolution. This performance could be improved using potentiometers with a higher resolution, but it would increase the price.

  • Henz, Dieter
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Heating Effect of Alternating Current on Lithium-IonBatteries at Subzero Temperatures2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electrification of transport is a distinct goal of many authorities. Electric vehicles are

    locally emission-free and can help to improve the air quality in cities. Despite several

    stimuli to promote electric vehicles, customers do not accept them at the desired level. One reason is the poor ratio between driving range and purchase cost. One possibility to tackle this poor ratio is to reduce complexity and weight of a battery pack, which helps to reduce its costs while increasing the driving range at the same time.

     

    Recent batteries in electric vehicles use lithium-ion technology. This type of batteries

    have a limited operating temperature, which requires pre-heating in cold ambient. In

    many electric vehicles pre-heating is realized with a heating element in the battery pack. This heating element does not only bring along additional weight but requires extra energy for distributing the heat. The idea of this study is to propose a more efficient heating method which is called alternating current (AC) heating. This method uses the internal impedance of a battery to generate dissipative heat, heating it up from inside.

     

    This work consists of practical measurements and experiments on a cell level as well

    as simulations. First, a literature research is conducted to present the latest heating technologies. Then, an impedance measurement is performed. The result of the impedance measurement is used to define the operating points for the following experiment. The experiment shows how AC frequency and amplitude influence the heating effect. The results from the impedance measurement and the experiment are further used to construct a cell simulation model that connects the thermal properties with the electrical properties. After verification of the model, the simulation is expanded to a battery pack level.

     

    The conclusion of the study is that it is generally possible to heat lithium-ion batteries

    with alternating current. Lower frequencies provide better heating effect at the same

    current amplitude and a higher current amplitude gives better heating effect than lower amplitudes. Therefore, the study also shows that further research is necessary to determine how the AC frequency affects aging of lithium-ion batteries at low temperatures. Finally, a method for increasing the current amplitude is proposed.

  • Politano, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Capability Perception of an Electric Utilityduring Sectoral Change towards Sustainability2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis examines the antecedents of employees’ capability cognition within a medium-sized electricity utility (Ntot 􀵎 1200) in German-speaking Switzerland. The firm implemented a new strategy in 2015 with the aim to shift its core capabilities towards sustainability.

    In the research field of organizational cognition and capabilities, various scholars have published work exploring how resources and capabilities are recombined to adapt to changing environments, but only relatively little about how capabilities are identified and evaluated within a company. While current literature  stresses that there are considerable differences in how managers, but also individuals, perceive capabilities, it has not yet been explored what the antecedents for the difference in perception are.

    This thesis will contribute to filling this research gap by identifying factors influencing capability perception of individuals in an electric utility during sectoral shift towards sustainability.

    Employees’ cognition of (i) environmental dynamism, (ii) their perception of, and (iii) participation in organizational change, (iv) the openness to change, as well as (v) perceived organizational

    identity in 2015are hypothesized to have a significant influence on the perception of capabilities in line with the new strategy assessed in 2016.

    To test the hypotheses, data was drawn from two-wave survey that has been conducted prior to this study in 2015 and 2016 (Nstudy = 358) exploring the implementation process of the new strategy, organizational climate as well as various characteristics of each individual.

    Consequently, the character-class statements of each employee are perceived score capabilities have been transformed into a numerical quotient, the percentage of capabilities in line with the new strategy. This information is then correlated with the perceived core capabilities in a regression analysis based on Structural Equation Models (SEM). When the perceived share of capabilities

    in line with the new strategy was predicted, it was found that

    participation in organizational change, openness to change, and perceived organizational identity were significant predictors. Environmental dynamism and organizational change were not significant predictors. The findings yield novel insights about what factors influence capability perception of employees in a changing external

    environment and bear important implications for practitioners about how to frame and facilitate organizational change towards sustainability.

  • Hu, Xinran
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Function Block Algorithm for Operation Planning on Cloud-DPP System: A case study of turbine disc from Sandvik Coromant2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project presented in this report is the outcome of a Master of Science thesis project which has been accomplished at Sandvik Coromant in Sandviken, Sweden. This Master’s thesis is part of a long-term effort devised by Sandvik Coromant, related the European research project CAPP-4-SMEs, which is a function block based on approach for distributed process planning combined with cloud manufacturing. The purpose of long-term version in Sandvik Coromant is to develop an industrial demo prototype system for agile process planning with embedded flexibility that also will enable implementation of functionalities for real time adaptation and control. This thesis project, as a part of the Sandvik Coromant major project, focused on operation planning part, analyzed and developed a demo software to implement it.

    Shop-floor uncertainty is an inevitable problem in manufacturing, especially in today’s market, the needs of customized products and service has greatly increased. How to improve production adaptability and reduce the time to deal with dynamic factors in production has become one of the core issues in the international industrial fields.

    In this Master of Science thesis project, the challenges of low adaptability in current process planning are discussed. In order to meet these challenges, the concept “Cloud DPP (Cloud - Distributed Process Planning)” combined with Function Block (FB) technology is applied to establish a process planning system that enables high degree of flexibility, automation as well as efficient resource sharing, scalability and accessibility regarding IT-systems and software applications.

    Taking a specific turning feature in aerospace engine as a case study, this project designs two schemes of integrated FB and distributed FB respectively. Two software demos are built, and the differences of modularization, accuracy and scalability are compared between the two systems.

    The result verifies the fact that the use of FB algorithm and cloud-DPP method significantly improves the adaptability of the process planning. In FB method, the distributed FB software system has better modularity and scalability.

  • Linschoten, Paul
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Pressure and Temperature Measurements in a Heavy-Duty Diesel Engine2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The values measured by the temperature and pressure sensors in the gas exchange system are important input parameters for several engine systems. This report focuses on the measurement and signal analysis of pressure and temperature, obtained at different positions within the intake and exhaust manifolds of a heavy-duty Scania diesel engine. Multiple sensors were placed in the intake and exhaust manifolds after which a series of pressure and temperature measurements were conducted at different engine speeds and loads. The experiments revealed that the sensor location does have a significant impact on the obtained signal. It was discovered that the boost pressure signal should be obtained as far from the charge air opening as possible, preferably in the intake port of cylinder 6. This position gave rise to the highest peak-to-peak pressure amplitude, which is preferable for detecting the valve events. The mean pressure at the different positions in the intake manifold deviated at most XX% from the actual mean pressure. The mean pressure deviations are basically constant over all tested engine speeds and loads, meaning that they are easy to compensate for with an offset. In the exhaust manifold, pressure should be measured at a position where several exhaust pulses converge. These positions were found to generate signals where the exhaust pulses could be detected at all the tested engine speeds and loads. The mean pressure deviations at the different positions in the exhaust manifold did not exceed YY% and were in contrast to the mean intake pressure not completely constant. The sampling frequency for the pressure signals in both the intake and exhaust manifold should be set no lower than ZZ Hz at 2300 rpm, as this could cause loss of relevant pressure data. The temperature measurements revealed that the temperature sensors should be placed at positions in the intake and exhaust manifolds where they are located far from the engine block and where there is a high mass flow of gas, as this decreases the impact of the engine block temperature as well as the sensor’s response time.

    Due to confidentiality, some of the results and measurements have been removed from this open version of the report. This was done by masking some of the axes in figures as well as by using letters/symbols to replace actual measured values.

  • Thibierge, Antoine
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Validation of a vortex panel method for aerodynamics and aero-elasticity of Wind Turbine2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ardema3D is a new type of vortex free model code that can simulate wind turbines.

    This code has been developed in order to replace the state of the art model, the blade

    element momentum (BEM). Indeed, the BEM is using strong assumptions and

    empirical correction, which are relevant for standard operation, however, there is a

    doubt on the validity of this model for complex situation. Ardema3D is developed to be

    substitute for the BEM when it is not valid.

    This code has been implemented in a coupled code, FARDEMAST, taking into account

    the elasticity of the blade and the controller. FARDEMAST is a code based on FAST, a

    code developed by the National Renewable Energy Laboratory (NREL), where the

    aerodynamic module has been replaced by Ardema3D. Both codes are under

    validation.

    The couple code FARDEMAST is computing the loads on the wind turbine, which are

    used to design the blade. Since vortex panel codes such as Ardema3D are using much

    less assumptions than the state of the art model for the industry, they are supposed to

    give more accurate results which can lead to safe and cheaper design for wind

    turbines.

    The Master Thesis proposed will cover two main topics of research :

    1. Validation of the far wake model of Ardema3D

    The free wake vortex model ARDEMA3D is accurate in terms of description of the

    unsteady forces on the blades and on the rotor near wake velocities. The far wake

    description is not so accurate.

    For the wakes, Adwen and the CORIA have been developing an actuator line model

    inside the Large Eddy Simulation code YALES2 for very advanced and detailed wake

    simulations. Several validations of the actuator line model have been initiated with

    respect to the existing bibliography.

    The most useful experimental results considered the analysis of wake velocity deficits

    downstream of a small scale wind turbine placed on a wind tunnel in the Norwegian

    University of Science and Technology (NTNU) in Norway.

    Based on the NTNU experimental setup, the work to be performed during this Master

    Thesis will be to compare the results of Ardema3D and the actuator line model both in

    terms of local rotor quantities such as forces, angle of attacks, etc, on blades, where

    ARDEMA3D is assumed to be more accurate together with the velocity deficit close

    and far from the rotor where YALES2 should have a better description and analyze the

    sources of the differences.

    2. Validation of the coupled code FARDEMAST

    After the validation of the aerodynamic code, the student will validate the use of the

    code for aero-elasticity purpose with the code FARDEMAST. The comparison will be

    done with FAST. The only difference with FARDEMAST is the use of an aerodynamic

    model based on the momentum equation, thus faster but less accurate. The validation

    will be done also with two structural models of FAST : ElastoDyn and BeamDyn.

  • Lefvert, Adrian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    The Swedish energy system and the role of hydrogen: a modelling study of the energy and transport sector2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In light of the ongoing climate change dilemma, and the consequences that a failure to reduce the greenhouse gas emissions to a stable level will most likely induce, there is an overwhelming consensus among scientists and political leaders that actions are necessary to ensure that adaptation and mitigation options are secured. The European Union, as well as the Swedish government, agrees with the Intergovernmental Panel on Climate Change and the United Nations Conference of Parties that a reduction of the fossil fuel dependency is essential. In respect of this, the concept of a hydrogen economy has been around as a promising solution to the current challenges that the energy systems faces, e.g. an increasing amount of renewable intermittent capacity.  This is calling for smart grids, demand side management and storage solutions. Hydrogen as an energy carrier can serve multiple purposes, as an energy storage for variable generation as well as a fuel for both the industry and the transport sector. Currently, there have been a few incentives to develop these so-called power-to-gas and power-to-power energy chains; however, progress is still slow. Before major investments can be seen in this technology, the potential will have to be evaluated thoroughly. In this thesis, the hydrogen potential costs and environmental benefits are assessed through energy modelling in the cost optimisation analytical tool OSeMOSYS (Open Source energy Modelling SYStem). Specifically, through scenario development, the potential use of hydrogen as fuel for passenger cars and buses has been analysed. The results show that although there is some potential for hydrogen use in fuel cell electric vehicles (FCEVs), the transition will be expensive and slow. Yet, a large reduction of emissions due to the shift from fossil fuels in the transport sector still makes hydrogen a relevant energy carrier to consider for the future. Continued efforts to assess the potential synergies of interconnecting the different energy sectors are necessary to understand its full potential.

  • Waldron, Marcus
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Smart window in Sweden: A comparative analysis of an office buildingsimulation model with conventional windows, andelectrochromic windows, based on Miljöbyggnadcertification criteria2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The building sector is one of the sectors that consume most energy in Sweden. Sweden aims thereby to reduce energy use in buildings by 20% by 2020 and 50% by 2050. To achieve these goals, more energyefficient buildings must be produced, and more energy-efficient measures must be implemented on existing buildings. Electrochromic windows are claimed to reduce the need for heating and cooling, as well as the need for artificial lighting. However, there is limited research on smart windows in the Nordic climate.

     

    This thesis examines electrochromic windows in Sweden, using the IDA ICE 4.7.1 simulation program. The study includes a comparative analysis of an office building model with conventional windows and motorized awnings, versus electrochromic windows with different control strategies, to investigate the building’s impact. In total, eight different scenarios are simulated in Stockholm, Umeå and Malmö. The electrochromic window scenarios consist of control algorithms where the windows are always on or off, as well as algorithms that respond to sunlight, daylight, operative temperature or scheduling. The conventional windows and awnings scenario represents the reference building. The Swedish building certification system "Miljöbyggnad" is used as a guideline for evaluating energy use, heating power demand, solar heat load, thermal climate, and daylight.

     

    The results show that electrochromic windows have little impact on the building. None of the scenarios succeed in obtaining higher certification than BRONZE, which corresponds to the authority's requirements for newly built buildings. However, electrochromic windows have a significant effect on the solar heat load and the lux level in the building, but unfortunately not enough to get a better building grade. There is no remarkable difference between the indicators and scenarios. Furthermore, the results show that scenarios that are shaded often (Always on, Daylight Control, Solar Control strategy) achieve GOLD ratings in solar heat load, but have the least impact on energy consumption and vice versa. Always off, Operative Temperature Control, and Schedule, Façade and Window strategy upgrades by one level in energy use. This confirm previous studies that claim that electrochromic windows have the greatest potential in energy saving in hot climate. This explains why there is hardly any difference between scenarios and cities.

     

    The thesis lacks specific costs for electrochromic windows. Thus, the cost estimate is based on generalizations and assumptions, in which the cheapest and most expensive options are investigated. If the building has well-functioning windows and awnings, it is not cost effective to switch to electrochromic windows, since the payback time is far too long. But if the building was between conventional windows and electrochromic windows during the planning phase, it might be interesting to conduct a detailed cost analysis. According to this study, the Operative Temperature Control strategy saves approximately 6 333kr during the simulation period. The cost differences between conventional windows with motorized awnings, and the cheapest version of electrochromic windows is around 60 000kr. This would provide a refund within 10 years, given that energy prices, energy consumption and currency value are the same. After that, the window would cut the energy costs in the form of saved energy.

     

    However, the study concludes that electrochromic windows are not necessary in this project from a Miljöbyggnad perspective, since the building grade remains the same and the economic gain is uncertain.

  • von Wowern, Per
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Design of an encoder converter forautomated non-destructive testing2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    WesDyne Sweden AB is a Non-Destructive Testing (NDT) company specializedin the examination methods ultrasonic testing, eddy current testing and visualinspection. To verify an examination procedure before the actual inspection atsite, a test rig consisting of a three or four axes motion system is used. WesDyne saw a need to be able to modify the position signals from the position encoders in order to increase the  exibility and in some case the accuracy when scanning objects with ultrasonic or eddy current probes. Thus, this thesis is regarding the design and evaluation of an encoder converter. The main task is to transform from Cartesian to polar coordinates and calculate the shortest distance between two points in space. Although, these calculations will introduce a delay. It is therefore of interest to look into how delays aect the NDT measurements.The selection of a microcontroller for the encoder converter was an importantpart of the thesis project. Initial tests were done with the Arduino Mega. Itwas concluded that more processing power was needed than the Arduino Mega could provide. The choice nally fell on the xCORE-200 eXplorerKIT fromXmos. The main tasks for the rmware developed for the xCORE-200 eXplorerKIT was to sample position signals, modify the signals and then output the modied signals. A printed circuit board was designed to act as an adapter card between the motorcontroller, measurement instrument and the xCORE- 200 eXplorerKIT. The encoder converter consisted of these two cards encased with supplementary components. A Windows graphical user interface application was developed to enable the change of settings of the encoder converter and overview of positions.Three tests with eddy current testing were done with a test block with emulated cracks in order to evaluate the performance of the encoder converter. The delay test showed that the Encoder converter had a maximal delay of 303 μs which corresponded to an average position error up to 0:12 mm. Two more tests with the test block were performed with the modied signals, polar coordinates and distance, from the encoder converter.The maximum average position error in these two test were 0:19 mm. The required accuracy depends on the circumstances but for most applications an error lower than 0:12 mm is acceptable. From the test results it can be concluded that conversion of position signals can improve accuracy in some cases of eddy current testing.

  • Zhu, Yaoxuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Huang, Xiaoting
    IMPROVEMENT OF COMPACTED GRAPHITE IRON DRILLING OPERATIONS WITH CUSTOMIZED CUTTING FLUID2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With its higher strength, Compacted Graphite Iron (CGI) is widely used in automotive industry. However, the machinability of CGI is challenging, mostly due to the high temperature in the cutting zone and the higher cutting force. This paper studies the influence of the different cutting fluids on the machinability of CGI material in drilling operations. The investigation compared a few customized cutting fluids having alkaline phase and oil phase, to a conventional cutting fluid. The oil phase of customized cutting fluid can help reduce the friction force in the machining process. The flank wear measurements showed there is no significant difference among the fluids. The thrust force measurements, however, showed that the customized cutting fluids could effectively reduce the cutting force by nearly 20%. By using the customized cutting fluid, the machining of CGI materials could either use higher feed rate to reduce cycle time when keeping the cutting force same, or use the same process data while reducing energy consumption.

  • Remy, Florian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Potential for the anaerobic digestion of municipal solid waste (MSW) in the city of Curitiba, Brazil2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Curitiba is a city of two million inhabitants located in the South of Brazil. It is a pioneer in waste management in the country, and is famous for its programs promoting recycling and organic waste collection. The city is now willing to take waste management one step further by investigating new solutions to treat and recover energy from organic municipal solid waste. This report is the fruit of a collaboration between two departments of the municipality of Curitiba, four local universities, the Swedish environment protection agency and the Royal Institute of Technology – KTH.

    The purpose of this report is to assess the potential for the development of anaerobic digestion as a solution to treat the organic municipal solid waste generated in Curitiba. The report offers an overview of the current waste treatment and of the main sources of organic waste in Curitiba. The annual amount of organic waste generated in the city is estimated to 144,350 tons, of which 913 tons come from food markets supervised by SMAB, the secretary of food supply. Three different scenarios, corresponding to three ranges of waste sources, have been considered. In the first one, the organic wastes generated by one of the two public markets of Curitiba are treated on-site. In the second one, all the organic wastes from food markets, street markets and popular restaurants are treated together in a medium-scale anaerobic digester. In the third one, all the sources of organic municipal solid waste identified in Curitiba are considered, including residential, institutional and small commercial waste.

    The annual methane production is estimated to 5,400 m3, 86,000 m3 and 12,600,000 m3 respectively for the three scenarios. In the last two scenarios, the methane could be converted into electricity, resulting in an annual electricity production of 257 MWh and 37,600 MWh. The first scenario does not consider a post-treatment of the digestate remaining at the end of the digestion. Between 46 and 50 tons of digestate could be used as a liquid fertilizer on-site and the surplus could be sold. For the two other scenarios, the digestate would be dewatered and composted to be sold as a dry fertilizer. The dry fertilizer production is estimated to 386 tons and 63,000 tons respectively every year.

    Each of the scenario considered would be financially viable, with a discounted payback period varying from 8 months for the small-scale scenario, to over 15 years for the second scenario. The third scenario would be the most lucrative, with a net present value of about 150 million reals.

  • NILSSON, AMANDA
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    ALVFORS, OSKAR
    KTH, School of Industrial Engineering and Management (ITM).
    Säljares riskpreferenser vid bostadsförsäljning2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • NIKYAR, SADAF
    KTH, School of Industrial Engineering and Management (ITM).
    The Impact of CSR on Investors’ Behaviour2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Haglund El Gaidi, Sebastian
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Partially Parabolic Wind Turbine Flow Modelling2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Climate change is an evermore urging existential treat to the human enterprise. Mean temperature and greenhouse gas emissions have in-creased exponentially since the industrial revolution. But solutions are also mushrooming with exponential pace. Renewable energy technologies, such as wind and solar power, are deployed like never before and their costs have decreased significantly. In order to allow for further transformation of the energy system these technologies must be refined and optimised. In wind energy one important field with high potential of refinement is aerodynamics. The aerodynamics of wind turbines constitutes one challenging research frontier in aerodynamics today.

     

    In this study, a novel approach for calculating wind turbine flow is developed. The approach is based on the partially parabolic Navier-Stokes equations, which can be solved computationally with higher efficiency as compared to the fully elliptic version. The modelling of wind turbine thrust is done using actuator-disk theory and the torque is modelled by application of the Joukowsky rotor. A validation of the developed model and force implementation is conducted using four different validation cases.

     

    In order to provide value for industrial wind energy projects, the model must be extended to account for turbulence (and terrain in case of onshore projects). Possible candidates for turbulence modelling are parabolic k-ε and explicit Reynolds stress turbulence models. The terrain could possibly be incorporated consistently with the used projection method by altering the finite difference grid layout.