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  • Andersson, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Spirometri med en smarttelefon: Utveckling av en app för att mäta rotationshastigheten till en spirometerprototyp för smarttelefoner2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal with this bachelor thesis was to develop an application with an algorithm to measure the rotation speed of a prototype, as a low-cost solution for measuring spirometry with a smartphone. In a pilot study it was investigated how a smartphone can be used to measure health and what algorithms there are to detect motion in videos. After the pilot study an app with the function to record a video by using the camera of a smartphone and then use an algorithm to detect the rotation speed in the spirometry-prototype’s turbine was developed. To make it work it is important that the rotation speed is low enough so it does not exceed half of the cameras fps. Therefore, to capture the rotation speed of the spirometry-prototype’s turbine the rotation needs to be limited and a smartphone with a camera with at least 120 fps is required.The result of this work is an algorithm that can measure the rotation speed in the spirometry prototype turbine. The algorithm is detecting the peaks in a PPG. To minimize the computation time and to increase the accuracy the algorithm analyses the colour intensity over a ROI in every frame. There is great potential to use this algorithm to further develop this alternative method of measuring spirometry.

  • Söder, Jenny
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Palmqvist, Markus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Prediktion av sannolikhet med maskininlärning och pris för sårbarheter i programvaruprodukter: Prototyper med algoritmer för prediktion av sårbarheter2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project explores the possibilities of predicting software product vulnerabilities and the type of vulnerability that will be found. It is an indication of how vulnerable a system is on how often a vulnerability is found. Machine learning is a way to read patterns from a large amount of data and can help with prioritization. With publicly available data on vulnerabilities, machine learning has been used to find a method of making predictions about the number of future vulnerabilities.

    prototypes have been developed and reviewed for which prototype that performs

    best. An analysis of the results shows that the content of the data should be evenly

    divided between classes in such type of survey to get a good and reliable result.

    The number of public vulnerabilities found and published has increased in recent

    years and appears to continue in the same trend. An analysis of how the market and

    selling price are looking for vulnerabilities shows that the global economy is growing

    rapidly and the turnover for machine learning will increase significantly as it

    recognizes its benefits to more areas.

  • Mossberg, Ivar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Dimensionering av dvärgbrytare för kraft- och spänningsmatningar på Forsmarks Kraftgrupp AB: Beräkningsmetodik och anvisning för dimensionering av dvärgbrytare.2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is performed on behalf of the department of Systemkonstruktion El at Forsmarks Kraftgrupp AB.This report deals with the task of making an inventory for miniature circuit break-ers (MCB). The aim of the graduation work is to design a quick reference so that the choice of cable and in some cases even MCB’s can be performed by the designer in connection with electrical design. This involves reporting a calculation method for selecting MCB’s in different applications. MCB’s in both AC voltage and DC voltage systems are affected.As reference for Forsmark, this report deals with the system 519.The problem lies in in delimiting the work since every reactor at Forsmark consists of approximately 4000 MCB’s of different characteristics and applications. A very huge importance is also given to parameters specified in SS-EN standards for load capacity.The thesis began with a pilot study of the pros and cons of MBC’s in different appli-cations, which rules control the dimensioning and how the design is carried out today, etc. An analysis was performed based on formulas and calculations present-ed in Swedish Standard such as SS 424 14 03, resulted in a quick reference.

  • Galdo, Carlos
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Chavez, Teddy
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Prototyputveckling för skalbar motor med förståelse för naturligt språk2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Natural Language Understanding is a field that is part of Natural Language Processing. Big improvements have been made in the broad field of Natural Language Understanding during the past two decades. One big contribution to this is improvement is Neural Networks, a mathematical model inspired by biological brains. Natural Language Understanding is used in fields that require deeper understanding by applications. Google translate, Google search engine and grammar/spelling check are some examples of applications requiring deeper understanding.

    Thing Launcher is an application developed by A Great Thing AB. Thing Launcher is an application capable of managing other applications with different parameters. Some examples of parameters the user can use are geographic position and time. The user can as an example control what song will be played when you get home or order an Uber when you arrive to a certain destination. It is possible to control Thing Launcher today by text input. A Great Thing AB needs help developing a prototype capable of understanding text input and speech. The meaning of scalable is that it should be possible to develop, add functions and applications with as little impact as possible on up time and performance of the service. A comparison of suitable algorithms, tools and frameworks has been made in this thesis in order research what it takes to develop a scalable engine with the natural language understanding and then build a prototype from this gathered information. A theoretical comparison was made between Hidden Markov Models and Neural Networks. The results showed that Neural Networks are superior in the field of natural language understanding. The tests made in this thesis indicated that high accuracy could be achieved using neural networks. TensorFlow framework was chosen because it has many different types of neural network implemented in C/C++ ready to be used with Python and alsoand for the wide compatibility with mobile devices.  The prototype should be able to identify voice commands. The prototype has two important components called Command tagger, which is going to identify which application the user wants to control and NER tagger, which is the going to identify what the user wants to do. To calculate the accuracy, two types of tests, one for each component, was executed several times to calculate how often the components guessed right after each training iteration. Each training iteration consisted of giving the components thousands of sentences to guess and giving them feedback by then letting them know the right answers. With the help of feedback, the components were molded to act right in situations like the training. The tests after the training process resulted with the Command tagger guessing right 94% of the time and the NER tagger guessing right 96% of the time.

    The built-in software in Android was used for speech recognition. This is a function that converts sound waves to text. A server-based solution with REST interface was developed to make the engine scalability.

    This thesis resulted with a working prototype that can be used to further developed into a scalable engine.

  • Public defence: 2018-03-21 13:30 hörsal F3, Stockholm
    Li, Nan
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Smart Cooperation with Network Coding in Hierarchical Wireless Networks2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    To achieve more dynamic, efficient and intelligent use of the scarce wireless spectrum resource, the concept of cooperation has been formalized into several hierarchical network models in future mobile networks. Cooperative communications, such as relaying, can potentially increase communication efficiency and spectrum utilization due to the broadcast nature of wireless networks, and may lead to a better support for diverse communication modes with flexible spectrum sharing. In this thesis, we investigate the cooperation between users with different priorities in hierarchical wireless networks. Especially, by coinciding the idea of relaying and network coding, we explore cooperation schemes from several aspects.

    First we discuss orthogonal time-frequency access for cooperation between primary and secondary users in a cognitive radio network, where two binary network coding schemes are developed. We analyze the transmission process and propose a novel methodology for performance evaluation. Second we propose a selective cooperation mechanism for intelligent resource sharing. By evaluating the system throughput with the approxiamtion method, we further discuss the spectrum sharing strategy by formulating an optimization problem to maximize the secondary system throughput. Besides, we extend our model to larger cognitive radio networks with multiple primary/secondary users. Finally we investigate non-orthogonal multiple access combined with orthogonal multiple access with hierarchical users. We define and study two cooperation schemes, where we derive the achievable rate regions with diverse communication modes supported. We formulate a problem jointly optimizing the strategy on time sharing and transmit power allocation at transmitters.

    Throughout the thesis we progressively reveal the importance of smart cooperation in hierarchical wireless networks, through rendering our models more realistic with smart strategies.

  • Davidsson, Victor
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Haptic Navigation in Virtual Reality: Investigating and developing guidelines for vibrotactile feedback using multiple types of information simultaneously2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, progress has been made regarding the use of tactile devices such as belts and helmets for navigational tasks. As most of the devices and solutions so far have focused on presenting one type of information at a time, the potential for tactile devices for simultaneous multiple tasks have yet to be properly explored. Based on such research, this study investigates various methods of presenting multiple simultaneous information using a vibrotactile head-mounted device for navigational tasks in a virtual space. The goal is to determine if it is possible to effectively present various simultaneous navigational information with vibrotactile feedback in a virtual space, and if so, determine guidelines for doing so while avoiding cognitive overload.

    Using a tactile head-mounted device known as the Perman Helmet various functions related to several navigational tasks in a virtual space were developed. These tasks were collision avoidance, object search and compass orientation. First a test was conducted to determine the most suitable solution for each given task. For each task three different types of solutions were developed, tested, and evaluated in an appropriate testing scenario.

    Afterwards, a second test was conducted to determine guidelines for how to combine those various solutions to present as much information as possible while avoiding cognitive overload. A new testing environment was created that incorporated all three tasks and various combination of the solutions were tested, along with two special configurations to test other factors.

    The results from the experiments shows that using several simultaneous vibrotactile signals representing different types of information is feasible and practical with at least 3 different types of signals. Furthermore, various types approaches and combinations have been considered and compared. Based on these findings, several guidelines when developing systems informing a user with multiple vibrotactile feedback signals have been proposed.

    These findings could help hasten the development of commercial and industrial multiuse vibrotactile devices, making it a relevant field of study.

  • Jonsson, Karl
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Two Problems in non-linear PDE’s with Phase Transitions2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is in the field of non-linear partial differential equations (PDE), focusing on problems which show some type of phase-transition. A single phase Hele-Shaw flow models a Newtoninan fluid which is being injected in the space between two narrowly separated parallel planes. The time evolution of the space that the fluid occupies can be modelled by a semi-linear PDE. This is a problem within the field of free boundary problems. In the multi-phase problem we consider the time-evolution of a system of phases which interact according to the principle that the joint boundary which emerges when two phases meet is fixed for all future times. The problem is handled by introducing a parameterized equation which is regularized and penalized. The penalization is non-local in time and tracks the history of the system, penalizing the joint support of two different phases in space-time. The main result in the first paper is the existence theory of a weak solution to the parameterized equations in a Bochner space using the implicit function theorem. The family of solutions to the parameterized problem is uniformly bounded allowing us to extract a weakly convergent subsequence for the case when the penalization tends to infinity.

    The second problem deals with a parameterized highly oscillatory quasi-linear elliptic equation in divergence form. As the regularization parameter tends to zero the equation gets a jump in the conductivity which occur at the level set of a locally periodic function, the obstacle. As the oscillations in the problem data increases the solution to the equation experiences high frequency jumps in the conductivity, resulting in the corresponding solutions showing an effective global behaviour. The global behavior is related to the so called homogenized solution. We show that the parameterized equation has a weak solution in a Sobolev space and derive bounds on the solutions used in the analysis for the case when the regularization is lost. Surprisingly, the limiting problem in this case includes an extra term describing the interaction between the solution and the obstacle, not appearing in the case when obstacle is the zero level-set. The oscillatory nature of the problem makes standard numerical algorithms computationally expensive, since the global domain needs to be resolved on the micro scale. We develop a multi scale method for this problem based on the heterogeneous multiscale method (HMM) framework and using a finite element (FE) approach to capture the macroscopic variations of the solutions at a significantly lower cost. We numerically investigate the effect of the obstacle on the homogenized solution, finding empirical proof that certain choices of obstacles make the limiting problem have a form structurally different from that of the parameterized problem.

  • Public defence: 2018-03-22 13:00 T1, Huddinge
    Askfors, Ylva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics.
    Samverkan för innovation: En fallstudie av mötet mellan akademi, industri och sjukvård2018Doctoral thesis, monograph (Other academic)
    Abstract [sv]

    Samverkan kan leda till innovation, konkurrenskraftiga företag, förstklassig forskning samt välfungerande myndigheter och institutioner. I den politiska debatten idag finns en förväntan att Sverige ska upprätthålla sin konkurrenskraft och bemöta samhällets utmaningar genom innovation och att vägen till innovation går via samverkan. Avhandlingen bygger på en studie av ett samverkansprojekt vars syfte var att skapa innovation för att minska antalet vårdrelaterade infektioner i Sverige. Projektet som studerats ses som en transdisciplinär ansats med aktörer som representerade akademi, industri samt hälso- och sjukvård.

    Syftet med avhandlingen är att vidareutveckla kunskapen om interorganisatorisk samverkan för innovation. Detta görs genom ett tredelat bidrag, till teoribildningen kring samverkan för innovation som börjat växa fram, till den samverkande praktiken inom både privat och offentlig sektor samt till politiker och beslutsfattare som styr fördelning av statliga anslag till forskning och innovation.

    Fallstudien som ligger till grund för avhandlingen är baserad på en etnografiskt inspirerad studie. Empiriskt material samlades in och skapades tillsammans med aktörerna i projektet under drygt två års tid genom intervjuer och deltagande observation.

    Studien visar att interorganisatorisk samverkan består av flera dimensioner och kan förstås på flera nivåer. Interorganisatorisk samverkan innebär inte bara att det är olika organisationer som ska göra en gemensam ansträngning. Organisationerna består av olika människor med olika discipliner och professioner vilka bygger på olika utgångspunkter och sätt att se på världen. Samverkan kan ses som ett sätt att fylla mellanrummen mellan organisationer istället för att bygga broar över gränser. I de organisatoriska mellanrummen kan aktörer från olika organisationer, med olika discipliner och professioner mötas utan institutionaliserade roller, i en receptiv kontext där innovation kan skapas.

  • Jonsson, Karl
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Highly oscillating conductivities with jumpsManuscript (preprint) (Other academic)
  • Jonsson, Karl
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    A multiphase hele-shaw flow with solidificationManuscript (preprint) (Other academic)
  • Ciftci, Bahadir
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Hur man utformar sin produktion med hjälp av Lean2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • Public defence: 2018-03-07 10:00 F3, Stockholm
    Fu, Qiliang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Wood Nanotechnologies for Transparency, Fire Retardancy and Liquid Separation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, wood nanotechnologies for transparent, fire-retardant and hydrophobic/lipophilic wood have been developed. There are two main parts; wood template preparation/processing concepts and materials design using these templates.

    In the wood template processing part, highly porous nanostructured wood templates are prepared. Relationships between processes and material structures are studied. Three chemical treatment methods are used. Lignin and/or chromophores are removed from cell wall, so that nanoscale pores are formed in the cell wall. For preparation of transparent wood, a lignin-retaining method improves physical properties of the template. The pore structures are characterized by scanning electron microscopy and gas adsorption measurement of specific surface area. The compositions of the templates are characterized. Compared with native wood, these templates have nanoscale porosity which provides opportunity for new types of wood modification.

    In the materials design part, wood nanotechnologies are used for transparent wood as well as for hydrophobic/lipophilic and fire-retardant wood. Two main strategies are used: i) nanoparticles are embedded inside the cell wall; ii) polymers are impregnated in lumen space, and sometimes also inside the cell wall. The transparent wood is prepared by MMA monomer/oligomer impregnation of lumen space. MMA has similar refractive index to the delignified template, so that scattering is reduced and transparent wood with favorable optical and mechanical properties is obtained. The structure and functional properties are studied. Laminated transparent plywood is designed to modify mechanical properties. Transparent wood and transparent plywood are demonstrated in applications combining loading-bearing properties with optical performance such as luminescent properties.

    The highly porous wood template cell walls are also impregnated with colloidal montmorillonite clay or epoxy/amine solutions to modify the cell wall and form nanostructured biocomposites. The structure and properties of the two materials are investigated; wood/clay hybrids for flame-retardancy and wood/epoxy biocomposites for oil/water separation.

  • Public defence: 2018-03-16 10:00 Kollegiesalen, Stockholm, Sweden
    Khan, Abdullah
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Towards the enhanced applicability of cold mix asphalt:: An experimental study focusing on surface free energies and the breaking and coalescence of bitumen emulsions2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The environmental, social and economic sustainability of our infrastructure network is clearly of paramount importance to the road-engineering sector as well to society at large. Sustainable road materials and reduced transport of those materials therefore play a significant role. Cold mix asphalt (CMA) emulsion technology could be one of the better options for the road industry to explore more thoroughly. Given its lower start-up and equipment installation costs, lower energy consumption and reduced environmental impact, CMA should offer a reliable alternative to some of the Hot Mix Asphalt (HMA) or Warm Mix Asphalt (WMA) options. As CMA is not a new technology, there are many reasons why this material is not currently being used as extensively as it might be. Though risk adverseness of the market may be partly to blame for this, a number of technical challenges and uncertainties related to material behavior are certainly responsible. This thesis has addressed some of the important technical challenges, aiming to provide more guidance in material selection and design, and prediction of the behavior of emulsion-based CMAs. To do so, this research has focused on aspects of the correct formulation of the bitumen emulsions, how to select the correct combinations of material components, and how to control the breaking and coalescence processes in bitumen emulsions better, resulting in usable and predictable adhesive and cohesive bond strengths. Though most of the laboratory and modeling choices that were made in this thesis are based on theoretical considerations, the main contribution is the test protocol development. The systematic surface free energy measurements of the material components, combined with the test set-up to monitor controllably the breaking and coalescence behavior of bitumen droplets in an emulsified environment, gives a new way to approach the design of CMA. It is recommended that future research is focused on taking the developed protocols as a basis for enhanced mix design and making a direct link to validated long-term mechanical properties on the asphalt mixture scale.

  • Shahin, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Al-Samarrai, Haya
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    EFFEKTIVISERING AV LOGISTIKFLO DET2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, one of the more complicated construction projects in Sweden is in full swing, namely the rebuilding of Slussen in Stockholm. The reasons for this are, among other things, that the former Slussen is in such a bad condition, and that the Mälaren regulation needs to be changed to allow for increased drawing of water. Located in the middle of the city and with about 450,000 people passing this meeting place daily, the parties involved to the reconstruction have limited conditions.Skanska is one of the many companies involved in enabling the rebuilding of Nya Slussen and the purpose of this work is to investigate how to streamline the logistics flow on one of Skanska's construction projects, SN 81 Art Construction Land. The aim of the study has been to locate the different parameters that adversely affect the logistics flow. The primary objective has since been to present action proposals that will increase value creation at the workplace and reduce / eliminate the waste items associated with the building.The method chosen for this study has been a combination of literature studies, survey and interviews. The survey was only shared with the construction workers on the project and the interviews have only been carried out for officials on the project selected according to experience and position to get a nuanced image of the subject.After this study, the critical parameters that affect the logistics flow negatively have been located. Space, communication and structure. Recommendations have then been worked out to increase value creation time and eliminate / reduce wasting items. The action proposals that were developed became an updated APD plan with storage areas given, external storage space, improved communication, simplified protocol management and, finally a structured worksite.

  • Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Effects of surfactants and adhesion promoters on the bitumen-minerals interfacial bond during breaking of bitumen emulsionsIn: Article in journal (Refereed)
    Abstract [en]

    Cold mix asphalt (CMA) emulsion technology has been the subject of research for many decades due to its proven environmental and economic benefits. However, issues relating to its mechanical performance still need to be investigated in order to understand the breaking mechanisms of bitumen emulsions and the surface chemistry involved. Bitumen emulsions are designed to break in a controlled manner to achieve the required level of performance for producing good quality cold asphalt mixtures. In this work, experiments on the coalescence of two bitumen droplets were carried out on a selected grade of Nynas bitumen. In an emulsion environment, the cohesion between bitumen droplets as well as their adhesion to a mineral surface was investigated. The cohesion and adhesion properties were analyzed by varying selected surfactant types and adhesion promoters in the water phase. The research showed that the presence of emulsifiers (with concentrations above the critical micelle concentration) in the water phase inhibits the adhesion of bitumen droplets to the mineral surface. However, a very small addition (0.02%) of adhesion promoter reverses the situation completely, and adhesion is dominant rather than cohesion. Moreover, the kinetics of the coalescence process is strongly controlled by the water phase temperature.

  • Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Investigating effects of salts on the coalescence process in bitumen emulsionsIn: Article in journal (Refereed)
    Abstract [en]

    The breaking and coalescence process in bitumen emulsions during their application strongly influences the resulting long-term mechanical performance of the cold mix asphalt. This phase separation process is affected by physico-chemical changes at the bitumen/water interface. This paper describes the effects of addition of different salts on the destabilization of bitumen emulsions. This study is limited mainly to cationic rapid setting (CRS) bitumen emulsions and salts which are very commonly added to these emulsions as a stabilizer. However, a few samples with non-ionic emulsifiers were also prepared and analyzed comparatively to understand the electrostatic force balance with varying concentrations of selected salts. The experimental part includes a bitumen droplet relaxation test, droplet size distribution measurement, microscopy, and evaluation of physico-chemical properties of prepared soap solutions e.g. interfacial tension and density measurements. Some experiments on the effect of selected water-soluble organic solvents on the coalescence process were also carried out. The results showed that coalescence was delayed after the addition of salts, while the water soluble organic solvents proved not to affect the emulsion significantly. 

  • Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modelling coalescence process during breaking of bitumen emulsions2016In: / [ed] International Society for Asphalt Pavements (ISAP), 2016, p. 1-12, article id Paper 61Conference paper (Refereed)
    Abstract [en]

    Cold mix bitumen emulsion technology is getting a lot of focus by the road industries since a few decades due to the diminished environmental impacts and reduced energy associated with it. The durability and mechanical performance of cold asphalt mixtures very much depend on the breaking, coalescence and phase separation processes in bitumen emulsions; however, the exact nature of the breaking mechanism of bitumen emulsion is not completely understood today. During coalescence or relaxation process, two bitumen droplets are completely fused into a unique spherical droplet and their kinetic is usually recorded in terms of time, denoted as relaxation time or τrelaxation.  In this work, a two dimensional Phase Field model was used to simulate the coalescence process of two bitumen droplets in water phase. The numerical model is based on Finite Element Method and solves Navier-Stokes system of equations coupled with the Cahn-Hilliard equation. The model predictions are validated by direct comparison with the experimental measurements performed in our previous work. Moreover, the study was extended to the small size (order μm) bitumen droplets which are difficult to produce and handle via experimental methods.  

  • Chanapai, Robin
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Tearing down barriers of photovoltaics with usability design: Winter is coming2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Photovoltaics has so far not seen much success in Sweden. Recent studies have shown that one of the reasons could be a lack of understanding of the technology, and a feeling that the lack of energy production during winter when a house’s energy consumption is the highest makes photovoltaics uninteresting. The ongoing research project Holistic business models and ICT solutions for prosumers seeks to increase the use of photovoltaics in Sweden, and have created business model concepts in an attempt to break perceived barriers of photovoltaics. My task in this project was to design a tailor made ICT solution with the users’ needs in focus.

    A series of interviews were conducted with households interested in photovoltaics to investigate what information is relevant to understand the business model, and create a starting point for the design process. To ensure a high level of usability of the ICT solution, an iterative design process was conducted with user tests between iterations.

    This resulted in a low fidelity prototype of a smartphone application, consisting of greyscale mockups. The prototype has as much as possible taken the interviewed households’ wishes into account, while adhering to design principles set for usability design. The interviews and user tests also gave some new insights into the informants’ attitudes towards the business model suggested by the research project, which is discussed at the end of the report.

  • Kimoto, Daiki
    KTH, School of Information and Communication Technology (ICT).
    Characterization and Modeling of SiC Integrated Circuits for Harsh Environment2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Harsh environment electronics, which can be operated at high-temperature, high-radiation, and corrosive gas environment, has been strongly desired in space exploration and monitoring of nuclear reactors. Silicon Carbide (SiC) is one of the candidates of materials for harsh environment electronics because of its high-temperature and high-radiation tolerance.‌

    The objective of this thesis is to characterize 4H-SiC MOSFETs at high- temperature and to construct SPICE models of the 4H-SiC MOSFETs. The MOSFET devices were characterized up to 500ºC. Using the characteristic of a 4H-SiC NMOSFET with L/W = 10 µm/50 µm, a SPICE LEVEL 2 circuit model was constructed. This model describes the DC characteristic of the 4H-SiC MOSFETs in the range of 25 – 450ºC. Based on the SPICE circuit model, the characteristics of operational amplifiers and digital inverters were simulated. Furthermore, the operation of pseudo-CMOS at high-temperature was analyzed and the operation principle of pseudo-CMOS was suggested.

    The device area and yield of pseudo-CMOS integrated circuits were estimated and it is shown that SiC pseudo-CMOS integrated circuits can use less area than SiC CMOS integrated circuits.

  • Klawitter, Martin
    KTH, School of Education and Communication in Engineering Science (ECE).
    Från Sverige till Arktis: En historik och diskursanalys om forskningen på fjärde generationens kärnkraft i Sverige: 2007 -20172017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since 2007 a Swedish research project have been attempting to develop “the next generation” of nuclear power plants, also called the fourth generation of nuclear power. In this study, I have partly adopted a historical perspective in order to investigate how this research project have developed and changed over time. I have also applied the methodology of Faricloughs critical discourse analysis in order to identify what kind of arguments and rhetoric’s that were used by some of the representatives of this project when they tried to convince the Swedish cabinet office in 2012 and the Swedish Energy commission in 2015 of the value of this technology. In the historical investigation, it was discovered that between the years of 2007 and 2017, the purpose and design of the proposed reactor had undergone several transformations and changes. At first, the leaders of the research project had been considering building a research facility in Sweden that would not only include a reactor, but also a fuel fabrication and reprocessing facility for production of plutonium fuel. However, the project was never approved by the Swedish government, after both KVA and Vetenskapsrådet had expressed criticism towards the project, due to both technical and socio-economic considerations. As a result, the direction of the project was transformed into commercial power production for the mining industry in the Canadian Arctic. In the discourse analysis, it became evident that the information and arguments that had been presented in the analysed material had been framed in a strictly positive and uncritical manner. The arguments that were portrayed had mostly addressed the theoretical possibilities of the technology, but very little about the realism of these visions. When opinions or values had been expressed, they had almost exclusively been phrased as inherent truths, which can contribute to both strengthening and upholding their status in society as authority figures. In the discourse analysis, I also discuss five different discourses which I have identified in the material that was analysed. These discourses were then concluded to be both reproducing and restructuring on the current order of Swedish nuclear and energy discourse.

  • Rodriguez-Cancio, Marcelino
    et al.
    University of Rennes 1.
    Baudry, Benoit
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    White, Jules
    Vanderbildt University.
    Images of Code: Lossy Compression for Native Instructions2018Conference paper (Refereed)
    Abstract [en]

    Developers can use lossy compression on images and many other artifacts to reduce size and improve network transfer times. Native program instructions, however, are typically not considered candidates for lossy compression since arbitrary losses in instructions may dramatically affect program output. In this paper we show that lossy compression of compiled native instructions is possible in certain circumstances. We demonstrate that the instructions sequence of a program can be lossily translated into a separate but equivalent program with instruction-wise differences, which still produces the same output. We contribute the novel insight that it is possible to exploit such instruction differences to design lossy compression schemes for native code. We support this idea with sound and unsound program transformations that improve performance of compression techniques such as Run-Length (RLE), Huffman and LZ77. We also show that large areas of code can endure tampered instructions with no impact on the output, a result consistent with previous works from various communities.

  • Johannisson, Wilhelm
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Light Weight Suspension System for KTH Research Concept Vehicle: DESIGN AND CONSTRUCTION OF A COMPOSITE SUSPENSION SYSTEM WITH FOCUS ON APPLICATION IN KTH RESEARCH CONCEPT VEHICLE WITH ANALYSIS OF FUTURE SOLUTIONS SUITABLE FOR THE AUTOMOTIVE INDUSTRY.2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project, the design of a transverse leaf spring for an automotive vehicle isinvestigated. A transverse leaf spring is a concept for implementing the traditionalcoil spring for the vehicle, into a spring operating through beam bending. There aredifferent constructions and layouts of said leaf spring developed previously. Onesolution is where the spring is spanning from one side to the other of the vehicle,making it a transverse leaf spring. This solution has an extra gain; it is also providingan anti-roll bar action to the ride characteristics of the vehicle.The design of the transverse leaf spring is made for an automotive research vehicle atRoyal Institute of Technology (KTH). This vehicle is designed to represent a smallcity vehicle, weighing approximately 600 𝑘𝑔. The design of the original suspensionsystem is of the type Double Wishbone with push rod and coil springs with damper.The system is modular and exactly the same for the front and rear of the vehicle.Original mounting positions on the vehicle are to be kept intact. The design of thetransverse leaf spring is made in order to mimic the exact characteristics of theoriginal suspension system.First analytical optimizations are made in order to find an initial solution. This designis then implemented in FEM-software in order to further investigate thecharacteristics and design. A final design is found that is fulfilling the requirementsand a full scale version of the transverse leaf spring is built and examined withregards to its fulfilment of requirements.

  • Ivarsson, Anna
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Conceptual design study of a modular fiber composite AUV2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The conceptual design of a modular AUV hull in fiber composite material has been determined. The goal has been to minimize the hull weight. Matrix and fiber materials have been investigated to find a composite combination that reduces the hull weight whilst being resistant to changes in the mechanical properties caused by submersion in water and the operational temperatures. A composite of a PEEK thermoplastic matrix with high strength carbon fibers is picked as the most suitable material option and used for hull calculations. Different composite part manufacturing processes are investigated to find a suitable method for the geometry and material that can produce high quality hull modules. Part quality factors such as fiber waviness and out of roundness in shape affects the collapse pressure of the hull. Filament winding adapted for a thermoplastic composite with in situ consolidation is picked as the most suitable manufacturing option.The structural designs considered for the hull are a fiber composite single skin construction (ring-stiffeners possible) and a sandwich construction, these would be manufactured as shorter modules that can be joined together to form the hull. The minimum hull thickness required for a single skin hull operating at 300 meters depth, considering material compression failure and buckling failure of the structure, is calculated for the PEEK/carbon fiber composite material. Buckling is the dimensioning failure mode of a thin walled cylinder with the AUV hull dimensions at the intended operational depth. The lay-up of the composite affects the thickness required so the lay-up is optimized to minimize the hull weight. For the cylindrical modules under hydrostatic pressure a [90/0/90] lay-up minimizes the thickness required and is the recommended lay-up. For comparison of hull weight with the existing AUV the minimum thickness required for a single skin hull in aluminium 7075 considering material compression failure and buckling failure of the structure is also calculated.From the analytical buckling analysis of a simple cylinder hull without joints the minimum thickness is determined as 11.82 mm for the composite hull and 15.23 mm for the aluminium hull, both values with a safety factor of 1.3 for the collapse pressure equating to 3.9 MPa. The single skin composite hull weight becomes 153 kg and the aluminium hull weight becomes 343 kg for these thicknesses. If the added stiffness of the structure from the joints would be taken into consideration it is expected that the thickness could be decreased further, but the relative weight difference between the composite and aluminium hull is expected to remain similar. From the finite element linear buckling analysis of the composite hull with thickness 11.82 mm the buckling pressure is determined as 3.39 MPa and for the aluminium hull with thickness 15.23 mm it is determined as 4.42 MPa.For a sandwich hull the minimum core thickness (using a weak core approximation and quasi-isotropic faces) is calculated as 19.96 mm, with safety factor 1.3 for the collapse depth and factor 1.1 for material failure of the faces. The weight for this sandwich hull with a carbon foam core becomes 72 kg. Based on a heat generation of 3 kW maximum during AUV operation heat transfer calculations through the thickness of the single skin composite hull give the maximum hull thickness as 50 mm before the AUV will overheat. The maximum 3 thickness of a regular PVC foam core sandwich hull is 4 mm and for a carbon foam core it is 21 mm before the AUV will overheat, making a sandwich with a carbon foam core a possible structural design choice but with some complicating factors compared to the single skin composite hull.

  • Treskatis, Tim
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Validation and Optimization of a non-cooperative Sense and Avoid System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To complement the established cooperative S&A system named TCAS which uses vertical avoid trajectories, Airbus Defence and Space developed a non-cooperative S&A System which favors lateral avoidance maneuvers. For this non-cooperative system, intruder aircraft are detected by radar before five different avoid trajectories are computed of which the best one is chosen. The presented work consists of the validation and optimization of this S&A System by simulating many different aircraft encounter scenarios. For validation purposes, the probability tables provided by the European Encounter Model (EEM) were used to compute the most probable aircraft encounters. As a result of the optimization process, the number of Near Mid-Air Collisions (NMACs) could be reduced significantly, and flight route constraints were included. More than 85,000 simulations were carried out to assess the performance of the system. The simulations revealed that the performance requirement for the S&A System, namely being at least as good as a human on-board pilot, could be fulfilled for encounter scenarios in which the ownship was flying level.

  • Saenz Molina, Flavien
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Vibroacoustic Analyses2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study of vibrations of structures is paramount in the aerospace industry, as parts are subjected to important dynamic loads. A vibroacoustic analysis of structures is thus undergone in order to ensure that they can withstand the acoustic environment. A validated in-house software was proven to be very reliable but commercial solutions could provide further options in terms of modelisation and decrease computation time while being as accurate as the in-house software. In this paper, a benchmark between ArianeGroup in-house vibroacoustic software and MSC Actran is carried out in order to evaluate their performance in terms of computation time. This comparative study shows that ArianeGroup in-house software and Actran converge towards the same PSD acceleration results and both softwares are consistent with SEA calculations at high frequencies. For a small model, the in-house software is as efficient as Actran but its performance decreases as the size of the model increases. A sensitivity study on Actran decomposition parameters shows that accuracy increases with the number of samples and plane waves used at a cost of an increased computation time. Yet, acceptable accuracy can be achieved without compromising on computation time.

  • Ojo Rus, Timi
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Topology Optimizationin a Multi Disciplinary framework for a Turbine Rear Structure2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis represents a research effort for the implementation of a structural optimization method known as Topology Optimization (TO) in a multi disciplinary work environment. This application is tested in a platform developed at GKN Aerospace Sweden named Engineering Workbench (EWB). The platform allows optimization of aerospace structures for several disciplines including thermo-mechanics, aerodynamics and producibility. It utilizes Knowledge-Based Engineering (KBE) tools to follow a Set-Based Concurrent Engineering (SBCE) and Design Of Experiments (DOE) approach. Consequently, this enables obtaining results from different disciplines for a large amount of design cases with limited human intervention. The implementation is performed taking a Turbine Rear Structure (TRS) as a use case. This is a component from a jet-engine which has been previously subject of study in EWB. The procedure already in use is extended in order to obtain TO results for a desired number of design alternatives automatically. This extension is done while considering the constraints imposed by the different disciplines. In addition, the positive contributions of the new procedure to the structural design of components are analyzed.

  • Malluzzo, Tomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Marine System Design in New Product Development under Technological Uncertainty2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Given  the  necessity  to  achieve  vertical  integration  in  complex  NPD  projects,  this  study  offers  a perspective  on  the  implication  of  customers  and  suppliers  involvement  under  technological uncertainty.  The  purpose  of  this  work  is  to  use  SoSE  in  order  to  develop  a  framework  that  may support Marine system design in NPD under technological uncertainty. It has been assumed that it is possible to achieve the Pareto optimum with respect to the key variables influencing the success of the NPD process; furthermore, this study will explore the possibility to tackle the goal misalignment between Customer, Suppliers and OEMs interacting in an evolving scenario and to offer a decisional ground  for  the  mitigation  of  such  misalignment.  Concluding,  the  purpose  of  this  study  has  been expanded by answering three research questions on how Technological uncertainty influences NPD in  Marine  System  Design,  what  alternative  frameworks  can  be  used  to  structure  such  designs  and how System of Systems Engineering can be used to build such alternatives. 

    The structure of the model built in this report is based on the concepts related to Enterprise System of Systems Engineering (SoSE), Agency Costs and Transaction Costs theories. The analysis is based on a  case  study  where  a  propulsion  system  has  to  be  developed  in  order  to  meet  the  incumbent environmental deadline imposed by the Policy maker, while taking into account future adaptations.    

    Basing  on  the  results,  the  largest  misalignments  pertain  to  the  Value dimension,  where  the  actors prioritized different features depending on their different positioning of the actors in the value chain, leading to an increase of the Agency costs in the NPD. On the other hand, the possibilities to share the  knowledge,  to  split  the  costs  over  the  involved  parties  and  to  reduce  the  Transaction  costs represent  the  main  advantages  perceived  from  the  actors.  An  integrative type  of  structure  of  the collaboration  within  the  actors,  for  instance  establishing  a  Joint  venture  or  through  Integrated development, would reduce the misalignments. 

    Finally,  ABB  can  use  SoSE  in  order  to  manage  its  internal  R&D  process  and  the  involvement  of customers  and  suppliers.  In  general,  SoS  can  help  OEMs  in  dealing  with  uncertainty  thanks  to  the concept  of  fluid  boundaries.  As  a  consequence,  the  integrated  system  will  benefit  of  greater flexibility while complying with the requirements given by the customers and the suppliers. 

  • He, Jincan
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Bhatt, Sundhanva
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Mission Optimized Speed Control2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transportation underlines the vehicle industry's critical role in a country's economic future.The amount of goods moved, specically by trucks, is only expected to increase inthe near future. This work attempts to tackle the problem of optimizing fuel consumptionin Volvo trucks, when there are hard constraints on the delivery time and speed limits.Knowledge of the truck such as position, state, conguration etc., along with the completeroute information of the transport mission is used for fuel optimization.Advancements in computation, storage, and communication on cloud based systems, hasmade it possible to easily incorporate such systems in assisting modern eet. In this work,an algorithm is developed in a cloud based system to compute a speed plan for the completemission for achieving fuel minimization. This computation is decoupled from thelocal control operations on the truck such as prediction control, safety, cruise control, etc.;and serves as a guide to the truck driver to reach the destination on time by consumingminimum fuel.To achieve fuel minimization under hard constraints on delivery (or arrival) time andspeed limits, a non-linear optimization problem is formulated for the high delity modelestimated from real-time drive cycles. This optimization problem is solved using a Nonlinearprogramming solver in Matlab.The optimal policy was tested on two drive cycles provided by Volvo. The policy wascompared with two dierent scenarios, where the mission demands hard constraints ontravel time and the speed limits in addition to no trac uncertainties (deterministic). with a cruise controller running at a constant set speed throughout the mission. Itis observed that there is no signicant fuel savings. with maximum possible fuel consumption; achieved without the help of optimalspeed plan (worst case). It is seen that there is a notable improvement in fuelsaving.In a real world scenario, a transport mission is interrupted by uncertainties such as trac ow, road blocks, re-routing, etc. To this end, a stochastic optimization algorithm is proposedto deal with the uncertainties modeled using historical trac ow data. Possiblesolution methodologies are suggested to tackle this stochastic optimization problem.

  • Guyon, Olivier
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Methodology for the Life Cycle Assessment of a Car-sharing Service2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, circular economy is becoming more relevant in society. In the context of the automotive industry, we no longer simply work on emissions emitted during the vehicle use phase but rather on the environmental impacts induced during all phases of the vehicle's life cycle (manufacturing, logistics, use, maintenance and end of life). For this purpose, many automakers, including the Group PSA, use life cycle assessment (LCA) to determine these environmental impacts. Also, the economy of sharing is gradually established and follows innovative uses of the car. New mobility systems emerge and compete with the classical system of sales of vehicles. These new uses of the automobile mainly take the form of car-sharing. In the future, it will become essential to evaluate these services from an environmental point of view.Some studies of the use of car-sharing already demonstrate important consequences such as reductions in the number of vehicles and in the number of kilometers traveled but also an increase in the use of other means of transport. However, to my knowledge, there is no LCA-based method to quantify the environmental benefit of the use of a car-sharing service in relation to the use of vehicles for exclusive use by the owner but also which would eco-design these services and the vehicles intended for these services.As part of this six-month project, a LCA approach was implemented to a PSA B2C (business-to-consumers) car-sharing service called “Emov” with a fleet of 500 Citroën C-Zero electric vehicles. The goal was to compare the use of Emov in Madrid, Spain with the urban use of a private Internal Combustion Engine (ICE) vehicle and a battery electric vehicle for one user characterized by its frequency, its average time and its average distance of use over a defined period. Thanks to a modeling of the service on the LCA software Gabi and by controlling over the input parameters related to the Emov service and the parameters related to the user's use of the service (variable parameters), it was therefore possible to show the influence of these parameters on the final results. Furthermore, it was possible to show also in which scenario it was more environmentally beneficial to use the service rather than a private vehicle. For the study, six impact indicators were chosen: the potentials for global warming, photochemical oxidation, air acidification, water eutrophication, resource depletion and primary energy demand.Using Emov’s big data to inform the service parameters and then varying the service user's usage parameters, it was possible to conclude that whatever the user's urban mobility needs, it is more beneficial to use the service than a private ICE vehicle for five of the six impact indicators. Only the acidification potential indicator (SO2 equivalent) is worse when using the service, which can be explained by the manufacture of the batteries of the Emov vehicles.

  • Corti, Fabrizio
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Viability of the overset method for geometrical sensitivity studies2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the following thesis the overset method, also called chimera or overlapping meshes, is discussed and applied toa formula race car, in order to calculate its aerodynamic map. The proposed method would allow reducing set-uptime through automation and avoided re-meshing process. a A theoretical background is presented before thediscussion of the way this kind of approach has been set-up in Star-CCM+. Results are obtained and discussedfor various car positions. Further investigations are finally suggested to further assess the viability of the method.

  • Eriksson, Andreas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    En lämplig standard för affärsprocesser i ett system2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Business process management (BPM) market has grown a lot in recent years. To have a good and compatible BPM system (BPMS) the developer of a BPMS should constantly keep their system up to date. There are several different standards in BPM. Within BPM these standards cover different areas. The focus in this report is on the area of notation standards. Some other standards have also been analyzed and discussed. Several standards have been evaluated and one of these has been implemented in a workflow foundation (WF) environment to see how well the standard implements in a system. To select a standard, analysis and discussions have been performed. From this information a list of demands was created to match the existing standards. Business Process Management Notation (BPMN) was the best matching standard and was elected for an implementation in the WF. The conclusion is that BPMN is a standard that should be prioritized within the development of a BPMS. The standard did not map to 100 % in the test in this report. This is because of the limitations of the WF flowchart. To implement BPMN in WF it is necessary to modify separate elements and WF has proven to be hard to customize. To make the BPMS support the whole BPMN the recommendation is to build a separate workflow engine. This way all the elements can be implemented, and full control will be given over the flow in the application. An alternative is to work with an open source workflow engine to get the source code and thereby can modify all the objects.

  • Public defence: 2018-03-16 14:00 F11, Stockholm
    Altafi, Nasrin
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Lefschetz Properties of Monomial Ideals2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the study of the Lefschetz properties of artinian monomial algebras. An artinian algebra is said to satisfy the strong Lefschetz property if multiplication by all powers of a general linear form has maximal rank in every degree. If it holds for the first power it is said to have the weak Lefschetz property (WLP).

    In the first paper, we study the Lefschetz properties of monomial algebras by studying their minimal free resolutions. In particular, we give an afirmative answer to an specific case of a conjecture by Eisenbud, Huneke and Ulrich for algebras having almost linear resolutions. Since many algebras are expected to have the Lefschetz properties, studying algebras failing the Lefschetz properties is of a great interest. In the second paper, we provide sharp lower bounds for the number of generators of monomial ideals failing the WLP extending a result by Mezzetti and Miró-Roig which provides upper bounds for such ideals. In the second paper, we also study the WLP of ideals generated by forms of a certain degree invariant under an action of a cyclic group. We give a complete classication of such ideals satisfying the WLP in terms of the representation of the group generalizing a result by Mezzetti and Miró-Roig.

  • Public defence: 2018-03-16 10:00 Q2, Stockholm
    Verginis, Christos
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Planning and Control of Cooperative Multi-Agent Manipulator-Endowed Systems2018Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Multi-agent planning and control is an active and increasingly studied topic of research, with many practical applications, such as rescue missions, security, surveillance, and transportation. More specifically, cases that involve complex manipulator-endowed systems  deserve extra attention due to potential complex cooperative manipulation tasks and their interaction with the environment. This thesis addresses the problem of cooperative motion- and task-planning of multi-agent and multi-agent-object systems under complex specifications expressed as temporal logic formulas. We consider manipulator-endowed robotic agents that can coordinate in order to perform, among other tasks, cooperative object manipulation/transportation. Our approach is based on the integration of tools from the following areas: multi-agent systems, cooperative object manipulation, discrete abstraction design of multi-agent-object systems, and formal verification. More specifically, we divide the main problem into three different parts.The first part is devoted to the control design for the formation control of a team of rigid-bodies, motivated by its application to cooperative manipulation schemes. We propose decentralized control protocols such that desired position and orientation-based formation between neighboring agents is achieved. Moreover, inter-agent collisions and connectivity breaks are guaranteed to be avoided. In the second part, we design continuous control laws explicitly for the cooperative manipulation/transportation of an object by a team of robotic agents. Firstly, we propose robust decentralized controllers for the trajectory tracking of the object's center of mass.  Secondly, we design model predictive control-based controllers for the transportation of the object with collision and singularity constraints. In the third part, we design discrete representations of multi-agent continuous systems and synthesize hybrid controllers for the satisfaction of complex tasks expressed as temporal logic formulas. We achieve this by combining the results of the previous parts and by proposing appropriate trajectory tracking- and potential field-based continuous control laws for the transitions of the agents among the discrete states. We consider teams of unmanned aerial vehicles and mobile manipulators as well as multi-agent-object systems where the specifications of the objects are also taken into account.Numerical simulations and experimental results verify the claimed results.

  • Yesilgul, Mustafa
    KTH, School of Education and Communication in Engineering Science (ECE).
    Formativ Bedömning i Matematik2017Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to investigate how the formative assessment takes place in the mathematic teaching in the elementary school later years and the teachers' experiences of formative assessment during their lessons. These investigations were conducted and analyzed based on Dylan Wiliam's five key strategies in formative assessment

    This work consists of a qualitative method that researches the human subjective experience within an area. The work was based on interviews with four high school teachers and classroom observations. The purpose of the interviews was to find out about the teachers' experiences of assessment processes and how they apply formative assessment during their math lessons. As a complement to the interviews, classroom observations were performed to see how these processes take place.

    The result shows that all math teachers have a positive view on formative assessment which must be supplemented with summative assessment. Furthermore, it is found that assessment should be done in a structured way, inter alia, by making assessment processes clear to students as far as possible and based on the control documents. The study also shows that teachers use different methods, including rapid reflections, Exit Cars and digital tools in form of formative assessment. The results also show that teachers find that formative assessment can be used to review students' current knowledge development and to provide adequate support to them in the future. On the other hand, the teachers feel that students' understanding of assessment, lack of time, difficulties with peer assessment can be a challenge in formative assessment.

    Another result shows that the teacher's assessment can focus on different processes that can deal with various levels of mathematical content.

  • Granqvist, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Hall, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Utfackningsväggar och trafikbuller - En förtätning av Albyberget2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    AUCTORITAS Projektstyrning AB is working on obtaining contract documents for two new apartment buildings in an environment that is exposed to noise. One problem that has arisen is to find an infill wall that meets the requirements for noise and U-value, which at the same time is economically justifiable. The authors, on behalf of AUCTORITAS Projektstyrning AB, have examined 10 different infill walls with regard to noise reduction, U-value and price. The purpose of the work was to investigate the technical properties of the infill walls.

    The question that was addressed was the following:

    • How does different materials affect the sound attenuation?
    • Which infill walls can handle the noise requirements of a new construction on Albyberget?
    • Can the problem be solved solely with the walls or does it require further action?
    • Is it economically justifiable to choose a thicker wall with regard to u value instead of maximizing the living space?

    In order to answer these questions, the authors have carried out laboratory work, literature studies and also taken part in a reference object, acoustics reports, energy calculation reports and costing books/offers. An interview with a person with knowledge in the area of noise/acoustics have been completed and used as a complementary basis.

    The results led to a recommendation of a standard timber frame wall with a thickness of 395 mm, that met all of the project requirements and with a cost of 1 391 kr/m2 to be used in the buildings at Albyberget.

  • Kostoulas, Christos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Container vessel maneuvering model in shallow waters and assessment of maneuvering coefficients through system identification2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A vessel operating in the real world has to overcome wind, waves and ocean currents. The result of all the above is a motion of 6 degrees of freedom (DOF). Typically, for the maneuvering phase, the Newton-Euler equations are used to derive the equation of motion of the rigid body and the maneuvering theory to model the external forces and moments acting on a vessel. The main topic in this Master Thesis is to assess the maneuvering behavior of a specific container vessel through a 4DOF model. The purpose behind this study is to investigate the differences between the expected maneuvering behavior of the vessel and the operational one. To accomplish that, raw data from the vessel’s sea trials were used and a time domain simulation model created with the sway-roll yaw movements coupled and surge decoupled. The Son and No moto maneuvering model served as the base for the motion equations. The maneuvering coefficients (MC) were firstly estimated by semi-empirical formulas using the vessel particulars. The model was validated using the Esso Osaka sea trials data. The validation was limited to maneuvering parameters such as advance, tactical diameter, yaw overshoot angle etc. The final model was used on the sea trials data of the container vessel taking into consideration the wind forces through the Blender mann wind model. Moreover, correction factors for swallow water effects were used on the MC in order to provide a better accuracy and also to allow comparison between the operational data and the simulated ones since the sea trials depth could not be considered as deep waters. Finally, a system identification procedure was perfomed in order to investigate the possibility of identifying the exact MC values of a vessel. The results were encouraging. The simulation follows the patterns of the raw data relative accurately. In addition, the swallow water corrections provided enough evidence of the different behavior of the vessel depending on the depth under keel. From the SI side, a list of issues were encountered like parameter drift, multicollinearity and cost function prone to local minimum. A series of different procedures and algorithm proposed to overcome those difficulties and the results were promising.

  • Agrawal, Harshit
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Gustafsson, Jacob
    Investigation of active anti-roll bars and development of control algorithm2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Active anti-roll bars have recently found greater acceptance among premium car manufacturers and optimal application of this technology has emerged as an important field of research. This thesis investigates the potential of implementing active anti-roll bars in a passenger vehicle with the purpose of increasing customer value. For active anti-roll bars, customer value is defined in terms of vehicle’s ride comfort and handling performance. The objective with this thesis is to demonstrate this value through development of a control algorithm that can reflect the potential improvement in ride comfort and handling. A vehicle with passive anti-roll bars is simulated for different manoeuvres to identify the potential and establish a reference for the development of a control algorithm and for the performance of active anti-roll bars. While ride is evaluated using single-sided cosine wave and single-sided ramps, handling is evaluated using standardized constant radius, frequency response and sine with dwell manoeuvres.The control strategy developed implements a combination of sliding mode control, feed forward and PI-controllers. Simulations with active anti-roll bars showed significant improvement in ride and handling performance in comparison to passive anti-roll bars. In ride comfort, the biggest benefit was seen in the ability to increase roll damping and isolating low frequency road excitations. For handling, most significant benefits are through the system’s ability of changing the understeer behaviour of the vehicle and improving the handling stability in transient manoeuvres. Improvement in the roll reduction capability during steady state cornering is also substantial. In conclusion, active anti-roll bars are undoubtedly capable of improving both ride comfort and handling performance of a vehicle. Although the trade-off between ride and handling performance is significantly less, balance in requirements is critical to utilise the full potential of active anti-roll bars. With a more comprehensive control strategy, they also enable the vehicle to exhibit different driving characteristics without the need for changing any additional hardware.

  • Kalakos, Dimitrios
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Westerhof, Bernhard
    Heavy Vehicle Braking using Friction Estimation for Controller Optimization2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis project, brake performance of heavy vehicles is improved by the development of new wheel-based functions for a longitudinal slip control braking system using novel Fast Acting Braking Valves (FABVs). To achieve this goal, Volvo Trucks' vehicle dynamics model has been extended to incorporate the FABV system. After validating the updated model with experimental data, a slip-slope based recursive least squares friction estimation algorithm has been implemented. Using information about the tire-road friction coefifcient, the sliding mode slip controller has been made adaptive to different road surfaces by implementing a friction dependent reference slip signal and switching gain for the sliding mode controller. This switching gain is further optimized by means of a novel on-line optimization algorithm. Simulations show that the on-line friction estimation converges close to the reference friction level within one second for hard braking. Furthermore, using this information for the optimized controller has resulted in reduction of braking distance on most road surfaces of up to 20 percent, as well as in most cases a reduction in air usage.

  • Söderman, Filip
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Uncertainty Analysis of the Aerodynamic Coefficients2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis treats an error propagation analysis used to estimate the uncertainty of the aerodynamic coefficients. The propagation methods used in this analysis are a Taylor Series Method and a Monte Carlo Method. The Taylor Series Method uses the partial derivatives of each input variable whereas the Monte Carlo Method uses random and repeated samples from the probability density function of each variable. By comparing the results obtained by the different methods, the results can be validated. Coverage intervals with a coverage probability of 95% are calculated along with the percentage contribution each input variable has on the expanded uncertainty. The results showed that the uncertainty of the coefficients varied between 10% and 20% and negligible differences between the methods were observed. More accurate measurements of the dynamic pressure and the position of the center of gravity are needed in order to decrease the uncertainty.

  • Cochelin, Paul
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Investigation of sandwich shells modelling in order to simulate with robustness the mechanical behaviour of the launchers upper part structures2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper presents the development of a finite-element model used to study the separation of a launcher payload fairing. This work has been carried out at the French National Space Agency (CNES). In order to capture the complex behaviour of sandwich structures used on the fairing, different methods are implemented to improve the robustness of the model and validate it. A special focus has been put on different shell theories available in the literature to understand the formulation behind shell finite elements. Several of them, available in the commercial solver Abaqus, have been tested to characterize their range of validity. The refinement suggestions drawn from this work have been implemented in the model and evaluated via a comparative study. No experimental data being available, a thorough process of verification and validation have been used in order to improve the confidence in the numerical results obtained.

  • Jackson, Eric
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    An Investigation of the Effects of Sustained G-Forces on the Human Body During Suborbital Spaceflight2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the advent of private commercial suborbital spaceflight, a new demo-graphic of untrained individuals will begin to travel to space. These individuals are exposed to high levels of G-forces, resulting in medical considerations which are not a normal factor with high performance fighter pilots or astronauts.The acceleration profiles of the Virgin Galactic and Blue Origin spacecraft were obtained from publicly available data. Video analysis was performed on footage of spacecraft test launches and human centrifuge tests to obtain individual data sets. These data sets were used to develop the acceleration profiles for both spacecraft. Based on the spacecraft’s acceleration profiles and peak G-forces, medical conditions were investigated and considered to identify potential risks that may affect the passengers, particularly the elderly.

  • Dumont-Le Brazidc, Joffrey
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    An Object-Oriented Data Analysis approach for text population2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With more and more digital text-valued data available, the need to be able to cluster, classify and study them arises. We develop in this thesis statistical tools to perform null hypothesis testing and clustering or classification on text-valued data in the framework of Object-Oriented Data Analysis.

    The project includes research on semantic methods to represent texts, comparisons between representations, distances for such representations and performance of permutation tests. Main methods compared are Vector Space Model and topic model. More precisely, this thesis will provide an algorithm to compute permutation tests at document or sentence level to study the equality in terms of distribution of two texts for different representations and distances. Lastly, we describe the study of texts regarding a syntactic point of view and its structure with a tree representation.

  • Hedén, Gustav
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Statistical evaluation model for future business opportunities of SAAB AB2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis conducts a statistical analysis of the won and lost sell data for SAAB AB. The method of choice is logistic regression analysis against believed and confirmed statistically significant dependable data. The sell data is split by different products so that each product gets an individual evaluation. The outcome of the regression analysis is then implemented on non-ventured markets for a specific product. This provide an implied probability of a successful sale of a product to different countries. These implied probabilities form a ranking of different countries for a specific product. The ranking tables are then supposed to be used as a statistical input for SAAB employees to use when evaluating potential future market gains.

  • Public defence: 2018-03-09 10:00 F3
    Motamedian, Hamid Reza
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Beam-to-Beam Contact and Its Application to Micromechanical Simulation of Fiber Networks2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This doctoral thesis covers the topic of modeling the three-dimensional fiber net- works with the finite element method. It contains the part addressing the numerical aspects of the modeling, namely, the contact formulation and application of the developed methods to the fundamental questions such as the effect of randomness in fiber properties and effect of fines and hygroexpansion.

    In the approached used in the work,  the fibers were meshed with beam elements  and the bond between fibers is modeled using point-wise beam-to-beam contact. Contact between beam elements is a specific category of contact problems, which  was introduced by Wriggers and Zavarise in 1997 for normal contact [1] and later extended by Zavarise and Wriggers to include tangential and frictional contact [2]. These formulations encompass a large number of derivations and provide the consistent tangent matrix. We showed, however, the resulting numerical implementations based on these consistent formulations are not sufficiently robust in modeling random fiber networks with a large number of contacts.  In the first papers, we proposed a simpler non-consistent formulation, which turned out to be superior in terms of convergence stability with respect to the load step size for a wide range of loading cases. Having these advantages, it remained equally accurate as the original formulation.  The first paper covered the formulation of normal and tangential contact, and the second paper contains two formulations with both the consistent and non-consistent linearizations for in-plane rotational contact of beams.

    We use the developed formulations to address fundamental problems within the area of fiber networks, which  cannot  be solved  purely  with  experimental  tools.  In  the third article, we investigated the effect of fiber and bond strength variations on the tensile stiffness and strength of fiber networks and concluded that in cases of skewed distribution, using mean values for fiber and bond properties instead of the distributions is not always adequate to assess the changes these properties have on the average mechanical characteristics of the entire network.

    In the fourth paper, the mechanisms behind the improvement of stiffness and strength after PFI refining in the papermaking process is investigated. The PFI refiner is very popular for studying the effect of refining in the lab scale. By using a combination of experimental and numerical tools, we found that density, which is often mentioned as  the main reason behind the improvement of mechanical properties after PFI re- fining, cannot solely explain the degree of the change observed experimentally. We concluded the remaining part of the improvement is caused by the fibrillar fines, in particular, by the fines that cannot be detected with modern automated fiber characterization tools due to the limited resolution of such tools.

    Finally, in the fifth paper, we suggested a multi-scale model to study hygroexpan- sion/shrinkage properties of paper. Due to the anisotropy of the fibers, the stress transfer at the bonded sites has a dominant role in the behavior of paper when exposed to moisture change. While we modeled the bonds between fibers using point-wise contact elements, such stress transfer requires a finite contact area. To solve this limitation and yet preserve the advantages for using beams for modeling fiber networks, we developed a concurrent multi-scale approach.  In this approach,  the bond model is resolved for every bond in the network, and the exchange between the network and bond model is maintained through the current configuration of the fibers being passed to the bond scale,  and the inelastic strains being transferred   back to the network scale. We demonstrated the effectiveness of such approach by comparing it with a full-scale continuum model.  Using this approach, we were able  to complete the existing experimental observation with key insights using the ad- vantage of having unlimited access to the details of the network at each stage of the deformation.

  • Amrén, Johanna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Nilsson, Ellen
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Interventions in Existing Buildings: Methods and Materializations2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Our aim with this project was to become more aware about the consequencesthat different kinds of changes or additions have on existing buildings andtheir characteristic architectural qualities. We have focused our study on thepart when a change or addition is designed, how the planned intervention isto be materialized, trying to understand how a change or addition relate to theexisting. Whether it is made to closely resemble that which is already there orcontrast in for example form, colour or material. In our thesis we call theseways of relating to the existing methods, and it is these methods that we havetried to identify, analyse and implement throughout this project.Some of the questions we have asked ourselves are:What different methods are there and how can they be materialized? How do theywork in combination? What effect do they have on a room and what do the differentmethods communicate?

  • Javaheri, Mahya
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Analyzing and Design of a Mosque in a Multicultural Society With Cultural Approach: Analyzing and Design of a Mosque in a Multicultural Society With Cultural Approach2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project attempted to detennine cultural factors in architecture and include these factors in architectural form and function. This work also aimed to determine the influence of certain contexts on architectural design specific to a certain region with a unique culture. This research focused on new identity, prestige, contexts and demands of contemporary Islamic architecture rather than design of novel, complex and eccentric forms in this new area. The present study conjured a sense of balance in the complexity, confusion and imbalance of new fonns. Some contemporary architects solely emphasize the past Islamic designs and ignore new contexts. On the contrary, others only focus on new contexts and neglect the past. Neither one is true. New designs should be based on the available space and context with regard to past fonns. In other words, the past heritage of architecture can influence the contemporary architecture if the new space and context can be fitted to the past. If not, new context is entirely unique and specific to the new space. Nevertheless, the preliminary principles of Islamic architecture should be preserved. The present project made some efforts to detennine the influence of different cultural and multicultural contexts on Islamic architectural designs (e.g. mosque). It sought to include other cultures in Islamic architecture. However, future studies are needed to clarify this issue.

  • Nanopoulos, Dionysios
    KTH, School of Engineering Sciences (SCI), Physics.
    Mechanistic modelling of swelling in the accident tolerant fuel candidate U3Si22017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Corticelli, Alberto
    KTH, School of Engineering Sciences (SCI), Physics.
    Topological Defects in Dirty Two-BandSuperconductors2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Eriksson, Love
    KTH, School of Engineering Sciences (SCI), Physics.
    Laboratory Tests of Prototype Components for the Satellite Polarimeter for High Energy X-rays (SPHiNX)2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Eriksson, Jesper
    et al.
    KTH, School of Engineering Sciences (SCI).
    Piroti, Shwana
    KTH, School of Engineering Sciences (SCI).
    Review of Methods for Energy Harvesting from a Vehicle Suspension System2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the increasing population the energy consumption has increased which makes the requirement for clean energy important, now more than ever. The transport sector is one of the biggest contributors to this consumption and should therefore be taken into consideration when looking for environmentally friendly solutions. The majority of fuel energy in road-bound vehicles of today is dissipated and is therefore never utilized. For a passenger car traveling at 13.4 m/s it is found that 200 W worth of energy is lost in the vehicles suspension system. The purpose of this work is to analyze and evaluate existing methods for energy regeneration from vehicle suspension systems in order to identify the most optimal solution. To end with, the report will propose mathematical models for simulations of the chosen system. This report examines electrostatic, piezoelectric and electromagnetic methods of energy regenera- tion and it is concluded that electromagnetic generators are the most viable when applied to vehicles. Furthermore, already existing ideas for regenerative suspension systems using electromagnetic generators are explained and compared. It is concluded that a suspension system using an electromagnetic generator coupled with a magneto-rheological (MR) damper is the most optimal when looking at e-ciency, cost, robustness and environmental impact. It can generate up to 90 W and is shown to be the most robust system because of its few moving parts. The working principle of the regenerative electromagnetic MR damper is explained and mathematical models describing the characteristics of the MR damper and the electromagnetic generator, based on previous work, are proposed. A simulation model using a quarter-car model is also proposed where dierent methods of road prole generation are suggested. The environmental aspects of the regenerative MR damper is conclusively discussed and evaluated so that the overall environmental performance of the system can be decided.