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  • Kviman, Oskar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Nilsson, Linus
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Applicability of a Translucent Barrier Based Model of Noise2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project was to create our own data set consisting of images of fruits and vegetables. A subset of the data set was composed of images where the fruits and vegetables were obscured by a plastic bag. We then evaluated the difficulty of this data set using a simple kernel machine algorithm. The performance drops considerably when introducing the above mentioned subset to the data set. The algorithm was to classify the different types of fruits and vegetables present in the data set. We also created the data set in different pixel dimensions, sufficiently reducing the computation time of the algorithm while not suffering a large drop in classification performance. This enables algorithms which complexity are highly dependent on input dimension size to use the data set. From our different experimental setups we were able to conclude that the machine outperforms humans on small input dimensions, given that the humans had no prior knowledge of the data set.

  • Krantz, Fredrik
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Modelling and Security Analysis of Internet Connected Cars2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With more and more Internet connected devices comes the question, are they secure enough. If such a thing as a vehicle were to be hacked there could be dire consequences. For example if someone acquired remote control of the brakes and steering of a vehicle they could be controlled with illicit intent. Several reports have shown that the internal networks of a vehicle with the protocols and devices used today are vulnerable to different kinds of attacks. So how can we make them more safe. The first step should be to show how vulnerable these systems are. This can be done in different ways. One way is to directly try to gain access to critical devices on a physical car i.e hacking it. Another way is to perform a manual security analysis of the car to map different vulnerabilities and and try to exploit those. A different way is to model the cars internal network with a tool that could do threat modelling and simulate attacks. One tool available being SecuriCAD. This tool is made with ethernet networks in minds and computers connected to these networks. An attempt to model in-vehicular networks shows to work with some adjustments. When a generalised model of a invehicular network is created in SecuriCAD the simulations shows vulnerabilities that correlates with what is shown in other reports. When modeling a 2014 Jeep Cherokee, the resulting attack tree of a replay attack given by the simulations is comparatively accurate to those attack steps made by Miller and Valasek when they hacked the same Jeep model in 2015. The method used in this project could be further improved but is a good proof of concept.

  • Hinas, Toni
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ton, Isabelle
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Recommender Systems for Movie Recommendations2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recommender systems are becoming a large and important market, with commerce moving to the internet and the ability to keep a larger stock of products, one of the biggest hurdles is to organize and show the right product to the right customer. Recommender systems aim at tailoring their products based on their customer need, by predicting how much a user would like a particular product. The recommender systems implemented in this project are within Collaborative filtering (CF) and Content-based filtering (CBF), with a final hybrid system based on combining the systems of CF and CBF. The aim is to evaluate how features such as number of latent factors, regularization factor and learning rate affect prediction accuracy for CF using Matrix factorization and compare the Root-mean square error (RMSE) for the three different systems.Collaborative filtering using matrix factorization resulted in lower RMSE than CBF and the largest factor in lowering error was learning rate. The results did indicate that CBF might perform better than CF when the user-base is small, while also having possibility of somewhat different functionality by recommending products which themselves are similar. The Hybrid recommender system had the lowest RMSE but with insignificant improvements from that of the CF method.

  • Ekvall, David
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Winqvist, Rebecka
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Machine Learning for Sleep Scoring2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In today’s society, Artifical Intelligence (AI) has become one of the most controversial research topics. The Artifical Neural Network (ANN) is a form of AI designed to mimic the human brain and is typically used for pattern recognition. This is especially useful within the medical field where ANN:s have already been implemented in a variety of applications. This project focuses on the possibility of extending the use of ANN:s to also be used to facilitate diagnosing sleep disorders, by investigating how well they can classify sleep states in rats.Two different types of network architectures were considered in this project: one fed with information from one single sleep state, and one fed with information from multiple consecutive sleep states. The highest classification accuracy achieved by the networks were 96.78 % and 97.02 % respectively.The networks were fed with features extracted from the provided Electroencephalography (EEG) and Electromyography (EMG) data of the rats. This enabled a reduction of the complexity of the ANNs, which resulted in low training times. It was concluded that feeding the network with extracted features from the data was a good approach, and that a network with access to information about several sleep states classified with the best accuracy.

  • Colérus, Lovisa
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Rehn, Karla
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Automatic sleep scoring using Keras2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sleep scoring is a diagnosis tool used for medical research. Using electroencefalography (EEG) a researcher observes the electrical activity in the brain and classifies the EEG into different stages. The goal of this project is to develop a tool for automatic classification of sleep data from rodents, one of the most common test subjects in modern medical research. EEG data from AstraZeneca is used to train a neural network, developed with Keras. Some augmentation of the data is done to increase the accuracy. The data is classified into different sleep stages with 91% accuracy.

  • Carlsson, Simon
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Näf, Max
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Internet of Things Hacking2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As the Internet of Things is gaining more traction in the market, people are becoming more comfortable with having their daily equipment connected to the internet, fewer are taking the security aspect seriously. By attempting an attack on the Telia Sense, an IoT device connected to a car, it is shown how an attacker could try to compromise this type of system and how developers and engineers in the field can test their devices. Information from the device was obtained, including debug information and program code. Telia Sense was found to be a well secured device with a lot of thought and consideration given towards cyber security, therefore a successful attack was not able to be performed. However, the methods and procedures described in this paper are still valid and does aid in securing a device.

  • André, Gustaf
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Testing a MIMO Channel for Stationarity2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is an increasing demand for better communication networks, e.g. better data rates and an improved bandwidth. As a response there is a lot of research being invested towards MIMO systems as a possible solution.In this paper data from a MIMO system with a fixed transmitter (8 antennas) and a mobile receiver (4 antennas) was investigated. The goal was to estimate the duration, during which, the MIMO system could be considered stationary. This was done by first estimating a correlation matrix for every time sample and then using the Correlation Matrix Distance function to measure how similar or dissimilar the different correlation matrices were within fixed time intervals. This was looked at from both the transmitter and receiver side. The result shows that the stationarity lasts for about 1.34 seconds and 5.2 seconds respectively for the receiver and transmitter.

  • De Ferrari, Giacomo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Development and Characterization of a Sustainable Lignin-based Composite Material2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lignin is the most abundant aromatic polymer of natural origin on earth. Currently, it is treated as a waste product of the paper production industry and is burnt as fuel to generate energy.

    Due to its renewable nature, it represents instead an optimum candidate to substitute non-renewable fossil-based feedstock for the production of plastic products. The present Thesis project deals with the development and characterization of a composite material, made of a lignin-based polymer matrix reinforced with glass fibers. The polymer blend used as matrix, composed of 50% by weight of lignin and 50% of DGEBA, once cured, was found to have a high gel content, corresponding to more than 97%. Moreover, it possesses a significant thermal stability: it starts to degrade at around 250 °C, it loses less than 5% of its weight up to 300 °C (of which 2% is water) and has its maximum degradation rate at 411 °C.

    Composites made of lignin-DGEBA matrix, reinforced with different contents of short glass fibers, from 10% to 60% of the matrix weight, were prepared. The developed composites showed a considerably decreasing porosity with increasing fiber content, up to the 50% glass fiber composite. In addition, from scanning electron microscopy images, a strong adhesion force between matrix and glass fibers was revealed.Furthermore, tensile tests showed that the produced composites have a good stiffness. In fact, the Young’s modulus varies from slightly more than 4 GPa of the 30% glass fiber composite to almost 5 GPa of the 50% composite, decreasing then in the 60% one.

  • Ovidiu Chelcea, Vlad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ståhl, Björn
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Deep Reinforcement Learning for Snake2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The world has recently seen a large increase in both research and development and layman use of machine learning. Machine learning has a broad application domain, e.g, in marketing, production and finance. Although these applications have a predetermined set of rules or goals, this project deals with another aspect of machine learning which is general intelligence. During the course of the project a non-human player (known as agent) will learn how to play the game SNAKE without any outside influence or knowledge of the environment dynamics. After having the agent train for 66 hours and almost two million games an average of 16 points per game out of 35 possible were reached. This is realized by the use of reinforcement learning and deep convolutional neural networks (CNN).

  • Jondell, Karl Johannes
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Implementation of an Automatic Control Strategy to Minimize Headway Variance2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this project, a model of a high-demand bus line is formulated and simulated. Three different control strategies, Timetable, Headway Thresholding and Self-Coordinating, are implemented and tested in the simulation, in order to establish one that reduces passenger wait time and that resists and recovers from bunching. Two of the three strategies uses inter-vehicle headways to control the flow of the buses, requiring real-time information sharing of vehicle positions between the buses. With the aid of so-called Automatic Vehicle Location-systems (AVL) already in use in many public transit systems, this information could be shared instantly through the Cloud and be used to make headway-based control strategies a reality.

    An interactive graphical user interface supplements the simulation software. This can be used as an educational tool for teaching about control theory and the dynamics of public transit systems.

  • Jerndal, Rasmus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Krödel, Ossian
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Portfolio Optimization with Market State Analysis2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis examines if portfolio allocation models can be reversed to find the investor’s perceived probabilities of different market states. This is achieved through a method which optimizes an inverted convex program with respect to market states from an assumed optimized portfolio of n securities. The concept the authors wished to explore was whether the actions of a known portfolio could be correlated to a set of factors in the market and further predict the portfolio management’s actions. This paper shows that such correlations are possible for simulated portfolios but does not dive deeper into the classification of markets, stocks and factors to solve the problem for a real portfolio.

  • Jacobzon, Gustaf
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Larsson, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Generalizing Deep Deterministic Policy Gradient2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We extend Deep Deterministic Policy Gradient, a state of the art algorithm for continuous control, in order to achieve a high generalization capability. To achieve better generalization capabilities for the agent we introduce drop-out to the algorithm one of the most successful regularization techniques for generalization in machine learning. We use the recently published exploration technique, parameter space noise, to achieve higher stability and less likelihood of converging to a poor local minimum. We also replace the nonlinearity Rectified Linear Unit (ReLU) with Exponential Linear Unit (ELU) for greater stability and faster learning for the agent. Our results show that an agent trained with drop-out has generalization capabilities that far exceeds one that was trained with L2-regularization, when evaluated in the racing simulator TORCS. Further we found ELU to produce a more stable and faster learning process than ReLU when evaluated in the physics simulator MuJoCo.

  • Lu, Zheyi
    KTH, School of Electrical Engineering and Computer Science (EECS).
    The Architecture of Blockchain System across the Manufacturing Supply Chain2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing popularity of blockchain - the cryptocurrency technology, the decentralized potential of the Blockchain technique is driving a new wave across the manufacturing industry. This paper introduce how to use the blockchain technique as a tool for solving supply chain related tasks in manufacture industry, and drive quantum leaps in efficiency, agility and innovation comparing with traditional centralized management system. This paper introduces the blockchain technique with its value properties and the requirement of this technique from manufacture industry. It also presents a clear blockchain architecture based on manufacture industry supply chain management mechanism describing its characteristics, unique consensus algorithms, smart contracts, network, scalability, databases. The paper also gives out a practical supply chain Dapp upon this architecture.

  • Glamheden, Mikael
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Eriksson, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Autonomous Trajectory Tracking for a Differential Drive Vehicle2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper explores controlling a two-wheeled differential drive vehicle using path planning algorithms and potential fields in order to track a target area while avoiding obstacles. Additionally, formation control was investigated using potential fields and a virtual structure approach separately. Finally, analysis of communication constraints in the form of sampling, disturbances and quantization are taken into account and theoretical or analysis results are given. It was concluded that the potential fields method result in an intuitive and dynamic controller that can be used to navigate within a large-scale and dynamic environment, as well as be used for formation control. The virtual structure approach is more robust when dealing with formation control, but it does not consider obstacle avoidance on its own.

  • Eriksson, Henrik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Löfgren, Victor
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Evaluating Different Algorithms for Detecting Change-points in Time Series2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Change-point detection is useful in many areas and there are several algorithms developed to cater specific needs such as fast calculations and statistical accuracy. In this report we outline five different algorithms, namely Fused Lasso, Filtered Fused Lasso, Normalized Fused Lasso, Dynamic Programming Approach and our own creation using convolution filtering, the Convolution Method. We evaluate them in the mentioned areas. Convolution Method is the fastest, Dynamic Programming Approach is the most accurate but suffers greatly in speed compared the other algorithms. Normalized and Filtered Fused Lasso performs similar in both speed and statistical accuracy. Although Fused Lasso is as fast as Normalized and Filtered Fused Lasso, it can not detect true change-points to any reliable extent.

  • Edlund, Joar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Jönsson, Jack
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Reinforcement Learning for Video Games2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We present an implementation of a specific type of deep reinforcement learning algorithm known as deep Qlearning. With a Convolutional Neural Network (CNN) combined with our Q-learning algorithm, we trained an agent to play the game of Snake. The input to the CNN is the raw pixel values from the Snake environment and the output is a value function which estimates future rewards for different actions. We implemented the Q-learning algorithm on a grid based and a pixel based representation of the Snake environment and found that the algorithm can perform at human level on smaller grid based representation whilst the performance on the pixel based representation was fairly limited.

  • Brunnström, Jesper
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Kaminski, Kamil
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Exploring Deep Reinforcement Learning Algorithms for Homogeneous Multi-Agent Systems2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Despite advances in Deep Reinforcement Learning, multi-agent systems remain somewhat unexplored, in comparison to single-agent systems, with few clear conclusions. In order to investigate this, two algorithms have been implemented and tested on a simple multi-agent system: Deep Q Learning with several improvements (EDQN) and Asynchronous Advantage ActorCritic (A3C). The result shows that with an increasing number of agents, learning a well performing policy takes more time. When only a few agents are used, the performance of both algorithms when fully trained is similar and could be viewed as satisfactory. With more than 3-4 agents the performance of the A3C algorithm decreases while EDQN maintains its good performance. Certain hyperparameters of these algorithms have been investigated and the results have been presented. In conclusion EDQN performs better than A3C with multiple agents. For both algorithms, there is a strong sensitivity with regards to the hyperparameters.

  • Broms, Philip
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Grönström, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Self-organizing Buses: a Headway-based Approach2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Urban transportation systems are a vital part of everyday life nowadays. One common, but difficult issue in this area is bus bunching which means that buses close in on each other eventually ending up platooning when in operation. This leads to inefficiency and passenger delay. The intent of this report is to develop a model for mitigating delays in urban transport by reducing bus bunching. Our approach is to have buses selforganize and focus on maintaining a consistent headway between buses. We propose using Markov chains in the algorithm. By assigning control points along the bus line that have the ability to evaluate the location of the buses. This dynamic property allows for a quick response to the unpredictability of urban traffic and an increase in effective use of the transportation system. Results show that self-organizing, headway-based control has the potential to significantly increase efficiency in urban transport.

  • Branzén, Erik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Hörngren, Johannes
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Model Predictive Control Design for Vehicle Platooning2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Platooning technology offers great benefits to society when it comes to increasing road capacity, fuel efficiency and fulfilling environmental goals. This paper investigates the issue of modeling a vehicle platoon and the design of a controller which fulfills some safety constraints, in particular regarding the relative distances of the vehicles within the platoon. More precisely, by the use of model predictive control, two different control strategies are examined a centralized controller and a distributed controller. To arrive at the design of a centralized and a distributed controller, two modeling schemes has been described, both based on a linear differential equation describing the dynamics of a vehicle in the platoon. In the centralized case, the platoon is viewed holistically and all vehicles are regulated by one central controller. In the distributed case, the platoon is viewed as a set of subsystems, each taking care of its own control problem and communicating with its neighbor. The performances of both controllers are evaluated via simulations and these simulations do not show any significant differences in performance given the platoon size investigated.

  • Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Light propagation in an anisotropically scattering medium2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Scattering is the main phenomenon of light-matter interaction. In this thesis, we consider one specific case of light propagation in a material whose structure causes anisotropic optical scattering - transparent wood. As a substance with properties interesting for research in optics/photonics, this biocomposite material began to be used quite recently, even though it was initially developed for the study of the internal structure of wood a few decades ago. Besides the anisotropy, the structure has a hierarchal arrangement with features ranging from nanometers up to micrometer sizes, and demonstrates short and long-distance natural ordering which is neither perfect nor totally random. The main interest in transparent wood within the field of optics is due to its remarkable combination of unique structure and optical transparency. There has been much research done on light propagation in diffusive media and/or structurally ordered materials, and in this sense, transparent wood occupies an intermediate niche for investigation. Since transparent wood is a relatively new material, there is a lack of methods of reliable study of its properties. Although there have been some attempts to characterize the optical properties of transparent wood via transmittance and haze (for scattering properties), insufficient understanding of the physical processes behind light propagation within the substance, scattering in particular, leaves a gap in data interpretation for measured parameters and their correlation with the material structure. In this thesis, we present our efforts to fill this gap through means of a more detailed and physically justified description of light propagation in an anisotropically scattering medium. In order to familiarize readers with the subject, we provide a short summary of the structural features, fabrication technology and chemical composition of transparent wood. We discuss issues related to the conventionally applied approach of haze measuring as a characterization method of the scattering in such anisotropic materials as transparent wood. We demonstrate a certain limitation of the haze criterion applicability and instead, suggest a modified characterization routine and parameters, such as transport mean free path, and degree of anisotropic scattering, for estimation of scattering properties of the material. We also discuss the dependence of scattering efficiency on the polarization state of incident light. Due to polarization-dependent scattering, unpolarized light propagating through transparent wood becomes partially polarized, with the angle of polarization oriented perpendicularly to the largest structural components of wood (vessels) which are co-aligned with the wood fibers. At the same time, the polarization degree of completely polarized incident light decreases after propagating through the material. The depolarization of light is attributed to the collective scattering by cellulose fibrils organized in the lamellae of cell walls of the fibers, and is strongly dependent on mutual v orientation of oscillations of the electric field (polarization of light) relative to the long axes of fibers. Transparent wood with its sponge-like structure can be an attractive platform for doping with various additives. In our project, we demonstrate an example of doping of a transparent wood template with organic dye (Rhodamine 6G). The combination of high scattering and optical gain results in the possibility of obtaining laser emission. By analogy with random lasers, there is no external resonator, however, the optical feedback is provided via scattering on inhomogeneity of the internal structure of the medium combining transparent wood and dye. The wood structure has a natural ordering, whereas in random lasers, in general, scatterers are randomly distributed within an active material. Therefore, we refer to such a laser as a “quasi-random” laser, to emphasize this difference. Based on experimental results and the comparative analysis with a reference sample (a polymer-dye), we have shown that wood fibers with highly scattering walls that are the main structural components of the transparent wood can operate as small lasers not correlated with each other. The collective origin of the laser emission of a wood-dye laser is reflected in the emission-line broadening of several nanometers. Measured low spatial coherence and high radiation brightness make this type of laser attractive for the application of speckle-free imaging and illumination. The work demonstrated in this thesis can be useful for further investigation and simulations of light scattering inside the biocomposite and similar anisotropic media. Moreover, the demonstrably successful example of expanding transparent wood functionality definitely creates new opportunities for further research and application of this substance.

  • Budnyak, Tetyana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Aminzadeh, Selda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Wallenberg Wood Science Center.
    Pylypchuk, Ievgen
    Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Allmas alle 5, SE-750 07 Uppsala, Swede.
    Riazanova, Anastasiia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Tertykh, Valentin
    Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17 General Naumov Str., 03164 Kyiv, Ukraine.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Peculiarities of synthesis and properties of lignin-silica nanocomposites prepared by sol-gel method2018In: Nanomaterials, Vol. 8, no 11, p. 1-18Article in journal (Refereed)
    Abstract [en]

    The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO2 nanostructured composites. We described the peculiarities of composites formation in the sol-gel process through the incorporation of the lignin into a silica network during the hydrolysis of tetraethoxysilane (TEOS). The initial activation of lignins was achieved by means of a Mannich reaction with 3-aminopropyltriethoxysilane (APTES). In the study, we present a detailed investigation of the physicochemical characteristics of initial kraft lignins and modified lignins on each step of the synthesis. Thus, 2D-NMR, 31P-NMR, size-exclusion chromatography (SEC) and dynamic light scattering (DLS) were applied to analyze the characteristics of pristine lignins and lignins in dioxan:water solutions. X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) were used to confirm the formation of the lignin–silica network and characterize the surface and bulk structures of the obtained hybrids. Termogravimetric analysis (TGA) in nitrogen and air atmosphere were applied to a detailed investigation of the thermal properties of pristine lignins and lignins on each step of modification. SEM confirmed the nanostructure of the obtained composites. As was demonstrated, the activation of lignin is crucial for the sol-gel formation of a silica network in order to create novel hybrid materials from lignins and alkoxysilanes (e.g., TEOS). It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials.

  • Hariramabadran Anantha, Krishnan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    An Experimental Study to Understand the Localized Corrosion and Environment-Assisted Cracking Behavior of AISI 420-Martensitic Stainless Steel2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Motivation and aim: Currently steel molds are designed with cooling channels to reduce the solidification time of molten plastic within the mold to improve the productivity. As water is generally used as the cooling medium, corrosion and environment-assisted cracking (EAC) leading towards the dysfunction of mold, can increase the production downtime. This was observed in some cases. Hence the primary aim of this thesis is to study the corrosion and EAC behavior of a martensitic stainless steel (MSS) in Cl containing environment to further the current understanding thereby to optimize the existing alloy/s and to design and develop new steel grades.

    Methods: The MSS had been austenitised at 1020°C, and subsequently quenched in nitrogen gas at fast (3°C/s), and slow quenching rates (0.6°C/s). Then tempering was done at 250°C, and 500°C, respectively, twice for two hours. Microstructure was predicted and characterized using Thermocalc simulation, dilatometry, light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy (AFM). Localized corrosion behavior was characterized using standard salt spray test, electrochemical experiments, scanning Kelvin probe force microscopy, in-situ AFM. Stress relaxation associated with 250°C, and 500°C tempering was characterized by a new method for both fast (FQ) and slow quenched (SQ) conditions. Based on the %stress relaxation, initial loading levels were altered and the corresponding environment-assisted cracking behavior was investigated at two different loading levels.

    Results: Samples tempered at 250ºC exhibited higher corrosion resistance than samples tempered at 500ºC in both FQ and SQ conditions. FQ samples exhibited higher corrosion resistance with an ability to passivate than SQ samples when tempered at 250ºC. However, when tempered at 500°C, the corrosion resistance was poor for both FQ and SQ samples. These observed differences clearly indicate the strong influence of microstructure on the corrosion behavior of the material. There are preferential active sites in the microstructure, which dictate the sequence of corrosion events. Secondary Cr-rich carbides formed during 500ºC tempering apparently deteriorate the corrosion resistance in spite of their smaller sizes as compared to undissolved Cr-rich carbides.  Stress relaxation increased with increasing tempering temperature. In the FQ condition, 250°C temper exhibited superior EAC resistance than 500°C temper in both loading scenarios, indicating the dominant role of corrosion resistance in delaying the failure. Whereas in SQ condition, 500°C temper exhibited superior EAC resistance than 250°C temper in both loading scenarios, indicating the dominant role of applied stress in delaying the failure. The pitting susceptibility increased with increasing applied stress on both FQ and SQ conditions. The fractographic features suggest that the mechanism of failure was mixed mode involving both active path dissolution and hydrogen embrittlement, which could have been operative during the failure in varying magnitude in respective scenarios. 

    Conclusions: Based on this research work, it can be concluded that, in order to have a longer service life, both the localized corrosion behavior and the residual stresses are to be considered while recommending tempering temperature to mold makers.

  • Beckman, Claes
    et al.
    Jörgen, Thaung
    Göteborgs Universitet.
    Johan, Sjöstrand
    Göteborgs Universitet.
    In vitro Lens Scatter Measurements and Glare Testing1994In: The Association for Research in Vision and Ophthalmology Annual Meeting. Sarasota, Florida, May 1-6, 1994. Abstracts. Investigative Ophthalmology & Visual Science March 1994, Vol.35, 1254-2383., 1994, Vol. 35, p. 1803-Conference paper (Refereed)
  • Nycander, Elis
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Eriksson, Robert
    KTH.
    Hamon, Camille
    Minimizing wind power curtailments using OPF considering voltage stability2018Conference paper (Refereed)
    Abstract [en]

    As the amount of wind power in power systems has increased it has become necessary to curtail wind power in some high penetration situations. In order to assess the need for curtailment arising from voltage stability considerations we develop a security constrained optimal power flow for minimizing the expected curtailment. We find that with a very high wind penetration and wind farms operating at unity power factor curtailment becomes necessary to satisfy voltage limits. In this case the optimal solution in the studied system is to curtail at a single bus rather than curtailing by a smaller amount at several buses. However, allowing for reactive power production from wind farms reduces the need for curtailments.

  • Tsegay, Haftom Tesfay
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Vibration caused by sheet pile driving- effect of driving equipment2018Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In many construction works in urban areas vibratory driving is the most widely used technique toinstall sheet piles. But due to vibration-sensitive equipment and structures the amount of inducedground vibration need to be minimized. Hence, it is important to select appropriate vibratorparameters that will minimize the level of induced ground vibration.The main objective of this thesis is to study the effect of the vibratory parameter eccentricmoment (vibrator displacement amplitude) on the induced ground vibration during sheet piledriving. To achieve the objective, a literature review and a full-scale field test has beenconducted. The literature review was conducted to provide guidance for the evaluation of thefield test results.The field study was performed in Uppsala in June 2018, where a series of six sheet pile drivingtests were conducted, the first three sheet piles were driven with lower vibrator displacementamplitude and the next three with higher vibrator displacement amplitude, but the same drivingfrequency was used for all six sheet piles. Five tri-axial accelerometers were used to measure thevibration amplitude on vibrator, sheet pile and ground.Important findings of the field study confirmed that, driving sheet piles with higher eccentricmoment will induce lower ground vibration and higher sheet pile penetration speed incomparison to driving with lower eccentric moment. Limitations and possible future researchworks are pointed out.

  • LINDÉN, ADAM
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    OLJEMARK, SIMON
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Managing Telework: Investigating Possibilities of Telework for Modern Organizations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Telework is a method of work that lets employees work from other places than the central office. With the world becoming more digitized, technology is becoming mobile and people become accessible wherever they are located. There are many benefits with Telework, but also many challenges that need to be taken into consideration. The digital era has led to that employees have changed their perception of how often they need to be at the central office, wishing to be more flexible and attain a better work-life balance. However, the adoption of Telework strategies has not grown as fast as first predicted by the originator, Jack Nilles, which some researchers after him have explained to be due to managerial resistance and lack of technology. This master thesis aims to investigate Telework as a phenomenon and explore how modern organizations can evolve to meet the demands of employees seeking more flexibility, but at the same time deal with challenges that may affect the organization negatively. Through a systematic literature review, we explore the concept of Telework and use previous publications in order to find common themes in research in order to find what may have impacted the decision-making process when organizations decide to implement Telework or not. A complementary literature study has also been used to investigate these themes further, which was followed by conducting empirical data collection through one semi-structured interview and two qualitative surveys. From our findings it can be found that common themes that act as drivers for Telework to be implemented are related to: an employee’s eligibility to reduce their commute, availability of digital infrastructure and ICT based tools and the organization’s possibility to cut cost related to office space. In our findings we have identified factors that organizations discuss before making a decision with regard to the implementation of Telework. Lastly, we see that how well an organization has adapted to a digital working environment does have impact on the adoption of Telework, given that there are many ICT solutions that can cope with the challenges Telework brings.

  • Polianskii, Vladislav
    KTH, School of Electrical Engineering and Computer Science (EECS).
    An Investigation of Neural Network Structure with Topological Data Analysis2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Artificial neural networks at the present time gain notable popularity and show astounding results in many machine learning tasks. This, however, also results in a drawback that the understanding of the processes happening inside of learning algorithms decreases. In many cases, the process of choosing a neural network architecture for a problem comes down to selection of network layers by intuition and to manual tuning of network parameters. Therefore, it is important to build a strong theoretical base in this area, both to try to reduce the amount of manual work in the future and to get a better understanding of capabilities of neural networks. In this master thesis, the ideas of applying different topological and geometric methods for the analysis of neural networks were investigated. Despite the difficulties which arise from the novelty of the approach, such as limited amount of related studies, some promising methods of network analysis were established and tested on baseline machine learning datasets. One of the most notable results of the study reveals how neural networks preserve topological features of the data when it is projected into space with low dimensionality. For example, the persistence for MNIST dataset with added rotations of images gets preserved after the projection into 3D space with the use of simple autoencoders; on the other hand, autoencoders with a relatively high weight regularization parameter might be losing this ability.

  • Hedencrona, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A Runtime Bounds-Checks Lister for SoftBoundCETS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Memory-safe execution of C programs has been well researched but the ability to find memory-safety violations before execution has often been overlooked. One approach for memory-safe C is SoftBoundCETS which infer some memory-accesses as statically safe and others become runtime-checked. One problem with this approach is that it is not obvious to the programmer which checks are runtime-checked and which are inferred as safe. This report analyses the approach taken by SoftBoundCETS by implementing a runtime bounds-checks lister for SoftBoundCETS.The resulting runtime bounds-checks-listing program that can track 99% of the inlined runtime bounds-checks to user program source code lines in programs compiled with -O3 and link-time-optimisation. Analysing SoftBoundCETS with this tool reveals SoftBoundCETS can eliminate about 35% of the memory loads and stores as statically safe in Coreutils 8.27.

  • Jan, Jonathan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Collecting Data for Building Automation Analytics: A case study for collecting operational data with minimal human intervention2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Approximately 40% of the total energy consumption within the EU is due to buildings, and similar numbers can be found in the US. If the principal inefficiencies in buildings were easily identifiable, then a facility manager could focus their resources to make the buildings more efficient, which would lead to both cost savings for the facility owners and decrease the building’s ecological footprint.

    In building automation systems today, data is already being collected every second, but due to the lack of standardization for describing this data, having access to data is not the same as being able to make use of it. The existing heterogeneity makes it very costly to gather data from multiple buildings, thus making it difficult to understand the big picture.

    Facility managers cannot fix what they cannot see; thus it is important to facilitate the visualization of the data collected from all of the different building automation systems. This potentially offers great benefits with regards to both sustainability and economy. In this thesis, the author’s goal is to propose a sustainable, cost and time effective data integration strategy for real estate owners who wish to gain greater insight into their buildings’ efficiency. The study begins with a literature study to find previous and on-going attempts to solve this problem. Some initiatives for standardization of semantic models were found. Two of these models, Brick and Haystack, were chosen. One building automation system (BAS) was tested in a pilot case study, to test the appropriateness of a solution.

    The key results from this thesis project show that data from building automation systems, can be integrated into an analysis platform, and an extract, transform, and load (ETL) process for this is presented. How time efficiently data can be tagged and transformed into a common format is very dependent upon the current control system’s data storage format and whether information about its structure is adequate. It is also noted that there is no guarantee that facility managers have access to the control system’s database or information about how that is structured, in such cases other techniques can be used such as BACnet/IP, or Open Platform Communications (OPC) Unified Architecture.

  • LUNDBERG, CLAES
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    UHNO, DOUGLAS
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Conceptual analysis of Risk Aspects within an InboundSupply Chain2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The global supply chain is fundamentally changing to become more complex as the world gets more connected. This causes high pressure on the supply chain to become resilient to a surrounding environment with more risks that affect financial aspects. In order to better understand what measurements and actions that need to be in place when strategizing on inbound supply chain theoretical frameworks needs to be built. To further understand how different risk factors are interlinked within the supply chain, it was decided to make use semi-structured interviews and the methodology called Total Interpretive Structural Modeling (TISM). The method chosen in this work is in accordance with the TISM methodology and is performed as follows: First, an extensive literature and interview process is carried out to identify important risks and how they drive cost. Secondly, utilizing experts knowledge by comparing logical statements against each other to create a hierarchical relationship between risks and cost drivers within the incoming supply chain. Third, Cross-Impact Analysis was utilized to better understand dependency and power and every variable. Finally, a self-explanatory model was developed based on the theoretical relationship between variables. At the same time, a qualitative study was executed. Based on semi-structured interviews with experts in the reas of Logistics & Supply Chain Management. The methodology for analyzing these semi-structured interviews is conducted in accordance with theories on the interpretation of qualitative data: transcribe, encode and index each interview to gain an understanding of the importance of data obtained. This qualitative study is conducted as a check to ensure that the result from the interpretation structure model (TISM) is consistent with reality. All done from a general and conceptual level applicable to the inbound supply chain of a manufacturing organization. The thesis found, by the use of above methodology, that there were 11 different risk factors that directly or indirectly relate to a financial cost driven in the supply chain. The hierarchy of these factors was established through TISM and cross-referenced with the expert opinions within the field of Supply Chain Management and logistics through semistructured interviews. Findings from the thesis conclude that important aspects of an inbound supply chain are (i) the importance of having a conceptual view of the market, strategy and organizational goal; (ii) implement an accurate accounting for materials and products to support transparency; (iii) logistics network and inventory is fairly unimportant in the whole picture; (iv) supplier relations needs to be kept up to standard, even in a seller’s market.

  • Ailenei, Ivona
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Kahn Skola2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The building is searching for the site’s existing landscape with it’s forests and an existing hidden glade that becomes the core of the project.

    The school is a place which is meant to be discovered step by step, in order to increase the creativity. And it acts like a heart, where the circle becomes a symbol for interaction and movement through the parts of the programme and the surroundings. 

    The building has its heart where the existing glade 

    exists.There are the smaller children, the kindergarden and the dining room which are directed outward. 

    A new , bigger glade is built for the children from the upper classes. This acts also as a social act between the society and the school. The big circle activates the place and takes the 

    children through all parts of the program. There will be an

    challenging investigation to move from the classrooms to the dining room and then to the school garden or the 

    workshops. 

    The classrooms take an articulated form that also

    encourages the idea of that  everyone should find her/his own place and provides a place for everyone.

    The workshops which are located on the ground floor open up to room where they can extend to the exterior  and where the children can work and have acces to the outside and where they can be seen and appreciated.

  • Tovatt, Tania
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Havsviksskolan2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Havsviksskolan takes into account its surroundings in its location on the specified site as it complies with the existing state form and picks up the direction of the Henriksdal alley rather than the adjacent motorway. The high tower contains classrooms from grades 3 to 6 that I have chosen to place on top of each other in order to leave as much space as possible for the school. The high-rise building relates to Backström & Reinius tower blocks. The lower part of the school stretches out like an "arm" from the tower and shields the school yard from the road. At ground level I’ve placed the pre-school, class 1 and 2 (grades I consider benefit most of direct contact with the ground). The floor above holds the classrooms for various subjects, staff rooms and dining area. On the contrary to the specific rooms of the tower the lower part of the school is flexible with many general open spaces - places for students to use in the way that suits them the best. The direction of the saw-toothed roof controls the planning and design of the special rooms. Light form the sky enters the building though windows facing north in the ceiling. This provide nice spaces despite the depth of the building which follows the gymnasium's width, 18 meters.

    The height of the gym is nine meters (7.5 meters excluding construction). The floor of the gym is one stories down below ground. It illuminates the school yard in the evening thanks to its open façade made of glass which also allows people on the yard/street to look at the activities in the hall. The construction is a so-called 'Pratt's Fackverk' in wood with steel diagonals.

    The facade of the school building is pinewood panel -treated with iron vitriol, which turn grey over time and interacts with the zinc ceiling.

  • Public defence: 2018-12-20 10:00 F3, Stockholm
    Björlenius, Berndt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Pharmaceuticals – improved removal from municipal wastewater and their occurrence in the Baltic Sea2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Pharmaceutical residues are found in the environment due to extensive use in human and veterinary medicine. The active pharmaceutical ingredients (APIs) have a potential impact in non-target organisms. Municipal wastewater treatment plants (WWTPs) are not designed to remove APIs.

    In this thesis, two related matters are addressed 1) evaluation of advanced treatment to remove APIs from municipal wastewater and 2) the prevalence and degradation of APIs in the Baltic Sea.

    A stationary pilot plant with nanofiltration (NF) and a mobile pilot plant with activated carbon and ozonation were designed to study the removal of APIs at four WWTPs. By NF, removal reached 90%, but the retentate needed further treatment. A predictive model of the rejection of APIs by NF was developed based on the variables: polarizability, globularity, ratio hydrophobic to polar water accessible surface and charge. The pilot plants with granular and powdered activated carbon (GAC) and (PAC) removed more than 95% of the APIs. Screening of activated carbon products was essential, because of a broad variation in adsorption capacity. Recirculation of PAC or longer contact time, increased the removal of APIs. Ozonation with 5-7 g/m3 ozone resulted in 87-95% removal of APIs. Elevated activity and transcription of biomarkers indicated presence of xenobiotics in regular effluent. Chemical analysis of APIs, together with analysis of biomarkers, were valuable and showed that GAC-filtration and ozonation can be implemented to remove APIs in WWTPs, with decreased biomarker responses.

    Sampling of the Baltic Sea showed presence of APIs in 41 out of 43 locations. A developed grey box model predicted concentration and half-life of carbamazepine in the Baltic Sea to be 1.8 ng/L and 1300 d respectively.

    In conclusion, APIs were removed to 95% by GAC or PAC treatment. The additional treatment resulted in lower biomarker responses than today and some APIs were shown to be widespread in the aquatic environment.

  • Chen, Hongjian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging.
    Evangelou, Dimitris
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging.
    Grishenkov, Dmitry
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging. Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    Sequence design for ultrasound imaging of polyvinyl alcohol microbubbles2019Conference paper (Refereed)
    Abstract [en]

    Nonlinear behavior of the ultrasound contrast agent (UCA) offers a unique feature to be distinguished from the surrounding tissue. In a recent years several methods were developed to enhance the nonlinear response of UCA. Crucial for efficient differentiation of the nonlinear response of UCA from the surrounding tissue is to design the contrast pulse sequence specific to the unique nonlinear properties that the particular UCA is offering.

    In the previous study, the nonlinear response from a novel polyvinyl alcohol (PVA) microbubbles (MB), in ultra-harmonic region was investigated over a pressure range from 50 kPa to 300 kPa. In this study, five contrast pulse sequences and reference B-mode sequence were designed to visualize PVA MB. The performance of those sequences were evaluated and compared.

  • Nilsson, Anders
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Energy Feedback and Demand Response Strategies: Exploring Household Engagement and Response Using a Mixed Methods Approach2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Real-time energy feedback (EF) and demand response using dynamic pricing tariffs (DR) have been suggested as effective intervention strategies to meet the need for increased energy efficiency and demand flexibility in the residential sector. Although previous studies provide some empirical support for the effectiveness of EF and DR, evaluation approaches used in practical experiments and field trials commonly suffer from several methodological shortcomings, preventing deeper of knowledge on the potential and barriers for EF and DR to influence household energy consumption.

    This thesis explored the potential of employing a mixed methods approach for evaluation of household energy consumption to provide improved understanding on how and why households engage and respond to EF and DR strategies. Three research objectives were set: 1) Analysis of the potential for using high-resolution data from smart meters in evaluation of household energy consumption and response to DR strategies, 2) development of a conceptual framework for evaluation of household responses to EF and DR strategies and analysis of its potential to increase understanding of household responsiveness, and 3) identification and analysis of household motivations, perceptions, and obstacles to engaging in EF and DR strategies.

    The work to achieve these objectives followed a mixed methods research methodology grounded on literature reviews and empirical studies in real-life settings in a single case study, an EF/DR field trial taking place in Stockholm Royal Seaport. A combination of quantitative and qualitative methods was used for data collection and analysis, comprising interviews, surveys, and statistical analysis of smart meter energy data.

    The results suggest that the mixed methods approach addresses several of the limitations and challenges associated with previous evaluation approaches. As regards objective (1), it was found that high-resolution data from smart energy meters can provide evaluation outcomes with increased transparency and accuracy. Regarding objective (2), it was found that the proposed framework can increase understanding of variations in household responsiveness to EF and DR strategies and reveal the relationship between impacts on electricity use and factors influencing energy consumption behavior. As regards objective (3), several obstacles for households to engaging in EF and DR strategies were identified, primarily related to household-individual factors such as knowledge, sense of control, and personal values and attitudes. Based on these findings, key issues and areas for further research are proposed.

  • Ulrici, William
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    TWO BIRDS WITH ONE STONE: Solving the Brittish and Swedish hosuing shortages with the same solutions2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When too many afford too little, one could claim that a housing market is malfunctioning. The United Kingdom and Sweden suffer from housing shortages in the major cities, creating low affordability, great strain on lower income groups and worse foundation for social sustainability. Considering matters such as different housing histories, political ideologies and policies, Sweden and the UK may seem quite unalike at first, resulting in expectations for two ‘distinct’ housing shortages. However, when a more thoroughly examination is made, it is possible the situation may appear different. Perhaps, it is even possible solving the British and Swedish housing shortages with the same solutions; two birds with one stone.

       The purpose with this thesis is to: analyse and compare the British and Swedish housing histories, identify challenges, present a few options to solving today’s low affordability, discuss how these shortages are solved so that affordable housing is obtained in both countries.

       To investigate this, the four questions:

     

    1.    Do Sweden and the UK have similar housing histories, and have they contributed to today’s shortages?

     

    2.    Are there similar housing challenges in Sweden and the UK?

     

    3.    Are there the same solutions to the housing shortages of Sweden and the UK?

     

    4.    Which are the most effective options for achieving an affordable housing future?

     

    ; were asked and tried to be answered.

       The intentions are that this thesis will be of use to housing debates in both countries, planners, professionals and decision makers, as well as interested and affected laymen, in search for knowledge concerning the reality they are faced with.

       Through examining the British and Swedish housing histories from 1946 to 2018, policies during the eras of the ‘Welfare State’, the ‘Liberal Society’ and the ‘State of Crisis’, the affordability challenges of tomorrow where formulated. To find possible options to face these challenges, five experts in the UK were interviewed, leading up to the four options concerning affordability; the market liberal: lowering construction cost and building smaller homes, and the social: local authority development / council housing and policy changes to increase social values in land.

       After analysing pros and cons with these options, their effect on increasing affordability and social sustainability were discussed, along with preventing further deregulation and privatisation of the housing markets as well as investing more in the countryside.

       The final recommendations and conclusions conclude that policies in both countries need to be changed if these housing shortages are to be truly ended and long-term sustainability on the housing markets achieved. To obtain affordability and stable housing markets, attitudes and policies throughout the societies would have to change towards viewing homes more as a human right, rather than a commodity. Another conclusion is that local authorities/councils have proven themselves to be capable developers in the past, which they can become yet again but only if the current systems change.

  • Wretling, Vincent
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability Assessment and Management.
    Strengthening the Municipal Energy Planning – Integration into Comprehensive Planning, Performance of Impact Assessment and Inclusion of National Environmental Objectives2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global climate is changing rapidly, which pronounces the need for transforming the energy system. The Swedish municipalities have been identified as key actors in Sweden’s decarbonisation due to their far-reaching responsibilities, which encompass energy planning. The municipalities are required to have a Municipal Energy Plan (MEP) regarding the provision of energy, but have increasingly shown climate awareness. Further, the municipalities are responsible also for the spatial planning, and increased climate efforts will largely be dependent on how this planning is conducted. However, the energy system also affects various other environmental impacts. Strategic Environmental Assessment (SEA) can aid to take these impacts and associated National Environmental Quality Objectives (NEQOs) into account, which is necessary in order to avoid that other negative environmental impacts occur due to a decarbonisation and that synergies between NEQOs instead could be utilised. Thus, this thesis aims to examine current municipal energy planning practice and the integration of energy and climate targets into comprehensive planning (Paper I), as well as to explore the performance of SEA and the consideration of NEQOs in municipal energy planning (Paper II). Further, suggestions for strengthening the practice is developed (Paper I and II).To achieve the aims, a document analysis, statistical analyses, thematic analyses and an interview study has been employed. This thesis shows that the Act on Municipal Energy Planning is not followed and that the municipalities proactively focuses on climate change mitigation instead. Moreover, a link between MEPs and Comprehensive Plans is seen regarding energy and climate-related targets, and a continuous energy planning can thus be one way of achieving a spatial planning in line with the climate objectives. SEA is seldom performed despite legal requirements, due to a deficient screening practice. However, when performed, SEA can increase the consideration of NEQOs, particularly those in which negative environmental impacts of climate efforts can occur. The consideration of NEQOs could thus help enhance synergies between a decarbonisation and other NEQOs, which could mobilise support for the MEP and aid its implementation.

  • Karbalaie, Abdolamir
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). KTH.
    Novel Analysis Toolkit for Capillaroscopic Images: Development and Clinical Evaluation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nailfold capillaroscopy (NC) is an invasive imaging technique that is used to assess the blood capillary network in the nailfold area. NC is routinely used for patients with microcirculation problems, such as systemic sclerosis and other connective tissue diseases. NC is repeatable and appears to be simple and harmless. However, there is a lack of established guidelines [QCE1] and instructions for both the acquisition and interpretation of the images obtained, which may lead to various ambiguities.

    The general aim of this thesis was to reduce the inherent ambiguities in human judgment and diagnosis by introducing novel techniques for assessing the nailfold capillary density, which is an important parameter in NC. To achieve this goal, a toolkit was developed that includes a method to measure the capillary density, an image enhancement technique and a graphical user interface (GUI).

    In the first study, a summary of the nailfold videocapillaroscopy procedure was presented, and the common techniques used to evaluate capillaroscopic parameters were reviewed. In the second study, common methods for calculating the capillary density were reviewed, and a survey of the relationship between the number of capillaries as well as the existence of digital ulcers, pulmonary arterial hypertension, autoantibodies, scleroderma patterns and the different scoring systems was performed. In the third study, a novel method was proposed to determine the nailfold capillary density, and this method is referred to as the elliptic broken line (EBL) method. In the fourth study, the EBL method for measuring capillary density was evaluated. In the fifth study, a new image enhancement technique was introduced and evaluated both subjectively and objectively. Finally, clinical applications of the EBL method and enhancement techniques were demonstrated in the sixth study. The result verifies the potential of the proposed EBL method to improve the reliability and repeatability of assessments. Additionally, improving the image quality, i.e., using the proposed enhancement method, can reveal more capillary details for an observer compared to the raw original image, and the results motivate the future development of automatic tools for the EBL method, e.g., automatic segmentation and capillary detection and characterization.

    Please note that the font changes here. Please consider using a consistent font type and size throughout the manuscript.

  • Plaza, Elzbieta
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Water, Sewage and Waste technology. KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Levlin, Erik
    Morling, Stig
    Falk, Lina
    Pilotförsök med MABR på Ekeby avloppsreningsverk: Teknisk rapport av ESEM, KTH & Sweco2018Report (Other academic)
    Abstract [en]

    This pilot project with membrane aerated biofilm reactor (MABR) was performed at Ekeby sewage treatment plant in Eskilstuna, Sweden. Ekeby faces a future challenge with growing population, where higher processing capacity is needed and new requirements for total nitrogen <10 mg/L in the discharge, according to the new standard. MABR, a newly developed technology with simultaneous nitrification and denitrification, was chosen as a promising technique to cope with the challenge. The trials were conducted for a 230 days period from July 12, 2017 to February 28, 2018.The pilot was designed as an activated sludge process with pre-denitrification with first an anaerobic tank where Zeelung membrane modules were placed, followed by an aerobic tank and finally a sedimentation unit where the return sludge was returned to the inlet. The feed water for the pilot comes from the treatkment plant's pre-sedimentation. Several analyzes were made on the inflow to the MABR reactor, in the volume with the Zeelung module, in the aerated volume and in outflow from the sedimentation tank. Ammonium content in incoming flow was 27 mg/L at the start of the trial to decrease to an average of 16 mg/L after day 60. Temperature in the inflow decreased during the experiment from 20 °C to 10 °C at day 124, to then stabilize on 12 °C. The reduction of organic material, such as BOD7, decreased from 90% at the start to 60% at the end of the trial, which is attributable to a lack of sludge separation in the final sedimentation.Nitrogen separation increased from 32 % at the start of the trial to an average of 53 % at the end of the trial. Nitrification in the Zeelung module increased from 27 % of oxidized nitrogen at the start of the experiment to 45 % at the end of the experiment. Along with the nitrification in the air volume, the nitrification of ammonium was almost total until day 175, January 3, when it fell sharply to the minimum 40 % on January 23, day 195, due to a combination of load and sludge from the sedimentation stage resulting in a shortened and insufficient sludge age. When the availability of organic carbon for denitrification was considered insufficient to cope with operation at low water temperature, and in combination with low levels of dissolved COD in incoming sewage, acetate was added from day 121. Prior to the addition of carbon source, the denitrification rate was on average 40% after the addition of carbon source, go up to 60% at the end of the test. The processes in the Zeelung module showed better operational stability than in the subsequent aerobic reactor.

  • Suarez, Andres
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Numerical simulation of multi-dimensional fractal soot aggregates2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Superaggregates are clusters formed by diverse aggregation mechanisms at different scales. They can be found in fluidized nanoparticles and soot formation. An aggregate, with a single aggregation mechanism, can be described by the fractal dimension, df , which is the measure of the distribution and configuration of primary particles into the aggregates. Similarly, a su-peraggregate can be analyzed by the different fractal dimensions that are found at each scale. In a fractal structure aggregate, a self-similarity can be identified at different scales and it has a power law relation between the mass and aggregate size, which can be related to properties like density or light scattering. The fractal dimension, df , can be influenced by aggregation mechanism, particles concentration, temperature, residence time, among other variables. More-over, this parameter can help on the estimation of aggregates’ properties which can help on the design of new processes, analyze health issues and characterize new materials.A multi-dimensional soot aggregate was simulated with the following approach. The first aggregation stage was modeled with a Diffusion Limited cluster-cluster aggregation (DLCA) mechanism, where primary clusters with a fractal dimension, df1, close to 1.44 were obtained. Then, the second aggregation stage was specified by Ballistic Aggregation (BA) mechanism, where the primary clusters generated in the first stage were used to form a superaggregate. All the models were validated with reported data on different experiments and computer models. Using the Ballistic Aggregation (BA) model with primary particles as the building blocks, the fractal dimension, df2, was close to 2.0, which is the expected value reported by literature. However, a decrease on this parameter is appreciated using primary clusters, from a DLCA model, as the building blocks because there is a less compact distribution of primary particles in the superaggregate’s structure.On the second aggregation stage, the fractal dimension, df2, increases when the superaggre-gate size increases, showing an asymptotic behavior to 2.0, which will be developed at higher scales. Partial reorganization was implemented in the Ballistic Aggregation (BA) mechanism where two contact points between primary clusters were achieved for stabilization purposes. This implementation showed a faster increase on the fractal dimension, df2, than without par-tial reorganization. This behavior is the result of a more packed distribution of primary clusters in a short range scales, but it does not affect the scaling behavior of multi-dimensional fractal structures. Moreover, the same results were obtained with different scenarios where the building block sizes were in the range from 200 to 300 and 700 to 800 primary particles.The obtained results demonstrate the importance of fractal dimension, df , for aggregate characterization. This parameter is powerful, universal and accurate since the identification of the different aggregation stages in the superaggregate can increase the accuracy of the estimation of properties, which is crucial in physics and process modeling.

  • KAREFLOD, MICHAELA
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    LJUNGQUIST, JENNIFER
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    The Impact of Sustainable Bonds2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Environmental changes and social instability are two great challenges of today’s society. The development of the sustainable bond market is a response to these. The demand is strong but there is no clear definition of the instruments and there is no standardised way of measuring the effect of them. The purpose of this thesis is thus to study the impact of sustainable bonds, and ways to communicate it to stakeholders. The research consists of nine interviews and the results are analysed in alignment with theoretical frameworks and models evaluated in a literature review. The key findings focus on suggestions for measures and creating a common language for reporting. The main recommendation for the commissioner is to undertake the following three steps: 1) Collect and aggregate all raw data from issuers into their systems. 2) Create harmonised values of the data. 3) Include soft and general values in the calculations.

  • Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Periodic Structures with Higher Symmetries: Analysis and Applications2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, periodic structures with higher symmetries are studied. Their wave propagation characteristics are investigated and their potential applications are discussed. 

    Higher-symmetric periodic structures are described with an additional geometrical operation beyond a translation operator. Two particular types of higher symmetry are glide and twist symmetries. Glide-symmetric periodic structures remain invariant under a translation of half a period followed by a reflection with respect to a glide plane. Twist-symmetric periodic structures remain invariant under a translation along followed by a rotation around a twist axis. 

    In a periodic structure with a higher symmetry, in which the higher order modes are excited, the frequency dispersion of the first mode is dramatically reduced. This feature overcomes the bandwidth limitations of conventional periodic structures. Therefore, higher-symmetric periodic structures can be employed for designing wideband metasurface-based antennas. For example, holey glide-symmetric metallic structures can be used to design low loss, wideband flat Luneburg lens antennas at millimeter waves, which find application in 5G communication systems. In addition, holey glide-symmetric structures can be exploited as low cost electromagnetic band gap (EBG) structures at millimeter waves, due to a wider stop-band achievable compared to non-glide-symmetric surfaces. 

    However, these attractive dispersive features can be obtained if holey surfaces are strongly coupled, so higher-order modes produce a considerable coupling between glide-symmetric holes. Hence, these structures cannot be analyzed using common homogenization methods based on the transverse resonance method. Thus, in this thesis, a mode matching formulation, taking the generalized Floquet theorem into account, is applied to analyze glide-symmetric holey periodic structures with arbitrary shape of the hole. Applying the generalized Floquet theorem, the computational domain is reduced to half of the unit cell. The method is faster and more efficient than the commercial software such as CST Microwave Studio. In addition, the proposed method provides a physical insight about the symmetry of Floquet modes propagating in these structures. 

    Moreover, in this thesis, the effect of twist symmetry and polar glide symmetry applied to a coaxial line loaded with holes is explained. A rigorous definition of polar glide symmetry, which is equivalent to glide symmetry in a cylindrical coordinate, is presented. It is demonstrated that the twist and polar glide symmetries provide an additional degree of freedom to engineer the dispersion characteristics of periodic structures. In addition, it is demonstrated that the combination of these two symmetries provides the possibility of designing reconfigurable filters. Finally, mimicking the twist symmetry effect in a flat structure possessing glide symmetry is investigated. The results demonstrate that the dispersion properties associated with twist symmetry can be mimicked in flat structures.

     

  • Lenkei, Zsolt
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Crowdsourced traffic information in traffic management: Evaluation of traffic information from Waze2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The early observation and elimination of non-recurring incidents is a crucial task in trafficmanagement. The performance of the conventional incident detection methods (trafficcameras and other sensory technologies) is limited and there are still challenges inobtaining an accurate picture of the traffic conditions in real time. During the last decade,the technical development of mobile platforms and the growing online connectivity made itpossible to obtain traffic information from social media and applications based on spatialcrowdsourcing. Utilizing the benefits of crowdsourcing, traffic authorities can receiveinformation about a more comprehensive number of incidents and can monitor areaswhich are not covered by the conventional incident detection systems. The crowdsourcedtraffic data can provide supplementary information for incidents already reported throughother sources and it can contribute to earlier detection of incidents, which can lead tofaster response and clearance time. Furthermore, spatial crowdsourcing can help to detectincident types, which are not collected systematically yet (e.g. potholes, traffic light faults,missing road signs). However, before exploiting crowdsourced traffic data in trafficmanagement, numerous challenges need to be resolved, such as verification of the incidentreports, predicting the severity of the crowdsourced incidents and integration with trafficdata obtained from other sources.During this thesis, the possibilities and challenges of utilizing spatial crowdsourcingtechnologies to detect non-recurring incidents were examined in form of a case study.Traffic incident alerts obtained from Waze, a navigation application using the concept ofcrowdsourcing, were analyzed and compared with officially verified incident reports inStockholm. The thesis provides insight into the spatial and temporal characteristics of theWaze data. Moreover, a method to identify related Waze alerts and to determine matchingincident reports from different sources is presented. The results showed that the number ofreported incidents in Waze is 4,5 times higher than the number of registered incidents bythe Swedish authorities. Furthermore, 27,5 % of the incidents could have been detectedfaster by using the traffic alerts from Waze. In addition, the severity of Waze alerts isexamined depending on the attributes of the alerts.

  • Yang, Yanpeng
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Ultra-Densification for Future Cellular Networks: Performance Analysis and Design Insights2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The traffic volume in wireless communication has grown dramatically in the lastdecade. Recent predictions indicate such data storm will be even more violent in theshort run. Potential solutions for accommodating the rapid traffic growth can besummed up into three categories: broadening the available bandwidth, improvingthe spectral efficiency, and densifying the infrastructure. In this thesis, we focuson the densification dimension which has been proven to be the most effectiveone in the past. The current gain of network densification mainly comes from cellsplitting, thereby serving more user equipment (UE) simultaneously. This trendwill decelerate as the base station (BS) density gets closer to or even surpassesthe UE density which forms an ultra-dense network (UDN). Thus, it is crucialto understand the behavior and design operations of ultra-densification in futurenetworks.

    An important question for future system design and operating strategy is whichelement is more effective than others. To this end, we start from comparing the effectivenessof densification with spectrum expansion and multi-antenna systems interms of meeting certain traffic demand. Our findings show that deploying more BSsprovides a substantial gain in sparse network but the gain decreases progressively ina UDN. Meanwhile, even with the same area throughput, different combinations ofindividual throughput and UE density lead to different requirements for resources.The diminishing gain appearing in UDNs makes us curious to know if there existsa terminal on the way of densification. Such uncertainty leads to the study onthe asymptotic behavior of densification. By incorporating a sophisticated boundeddual-slope path loss model and practical UE densities in our analysis, we present theasymptotic behavior of ultra-densification: the coverage probability and area spectralefficiency (ASE) have non-zero convergences in asymptotic regions unless theUE density goes to infinity (full load). Our results suggest that network densificationcannot always improve the UE performance or boost the network throughput.

    Next, we shift our focus to the operations of UDNs. We first study BS cooperationsin two UDN scenarios: homogeneous and heterogeneous UDNs which aredistinguished by BS types. In both cases, the cooperation rules become more complicatedthan those in traditional networks. Either channel state information (CSI) orextra delay information needs to be acquired in order to obtain cooperation gains.At last, we investigate the feasibility of applying random beamforming to initialaccess in millimeter-wave (mmWave) UDNs. To our surprise, the simple methodcan provide sufficient performance in both control and data plane, comparing withthe existing schemes. Therefore, it may be unnecessary to develop complex algorithmsfor initial access in future dense mmWave networks. The findings indicatethat UDN may complicate network operations while it may also facilitate the use ofsimple schemes. Our work provides insights into the understanding of the networkdensification and thus paves the way for the operational design of future UDNs.

  • Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Eriksson, Jon
    Mutual coupling effects on direction of arrival estimation1996In: In Radiovetenskaplig konferens, Luleå, Sweden 1996 / [ed] Lars H Zetterberg, 1996, p. 410-414Conference paper (Refereed)
  • Zakipour Mahmoudi, Anna
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Englund, Leila
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Användarupplevelsen av en mobilapplikation - En utvärdering av företaget Amazing Leaders' prototyp2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During the past decade the useage of smart mobile telephones have increasedtremendously. As a result, alot of research has been undertaken in the eld of HCI(Human-Computer Interaction). From HCI, the study of the interaction betweenusers and computers, the scientic eld of User Experience (UX) has emerged. User experience, as a whole, refers to a person's overall experience about using aparticular product, system or service.

    The organization Amazing Leaders have developed a prototype in order toimplement their future mobile application. The implementation of the applicationwill be executed by the IT-company VNTRS. VNTRS and the authors undertakethis bachelors thesis in order to study the characteristics of the prototype, withthe aid of concepts taken from the research area of UX, in order to understandwhat Amazing Leaders' intended end-users have thoght to be the most importanttraits of the prototype in relation to the user experience. Using Hassenzahl's UX framework and Laugwitz et al. characteristics of the user experience, theprototype was examined by use of surveys and focus groups.

    Using the data collected from the surveys and focus groups, the most importantcategorization for the prototype could be established and recommendations on future work made.

  • Wang, Wei
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    WebRTC Quality Control in Contextual Communication Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Audio and video communication is a universal task with a long history of technologies. Recent examples of these technologies include Skype video calling, Apple’s Face Time, and Google Hangouts. Today, these services offer everyday users the ability to have an interactive conference with both audio and video streams. However, many of these solutions depend on extra plugins or applications installing on the user’s personal computer or mobile device. Some of them also are subject to licensing, introducing a huge barrier for developers and restraining new companies from entering this area. The aim of Web Real-Time Communications (WebRTC) is to provide direct access to multimedia streams in the browser, thus making it possible to create rich media applications using web technology without the need for plugins or developers needing to pay technology license fees.

    Ericsson develops solutions for communication targeting professional and business users. With the increasing possibilities to gather data (via cloud-based applications) about the quality experienced by users in their video conferences, new demands are placed on the infrastructure to handle this data. Additionally, there is a question of how the stats should be utilized to automatically control the quality of service (QoS) in WebRTC communication systems.

    The thesis project deployed a WebRTC quality control service with methods of data processing and modeling to assess the perceived video quality of the ongoing session, and in further produce appropriate actions to remedy poor quality. Lastly, after evaluated on the Ericsson contextual test platform, the project verified that two of the stats-parameters (network delay and packet loss percentage) for assessing QoS have the negative effect on the perceived video quality but with different influence degree. Moreover, the available bandwidth turned out to be an important factor, which should be added as an additional stats-parameter to improve the performance of a WebRTC quality control service.

  • Moosavi, Per
    KTH, School of Engineering Sciences (SCI), Physics.
    Non-equilibrium dynamics of exactly solvable quantum many-body systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Recent experimental advances on ultracold atomic gases and trapped ions have made it possible to simulate exactly solvable quantum systems of interacting particles. In particular, the feasibility of making rapid changes, so-called quantum quenches, to such set-ups has allowed experimentalists to probe non-equilibrium phenomena in closed interacting quantum systems. This, in turn, has spurred a considerable theoretical interest in quantum many-body systems out of equilibrium.

    In this thesis, we study non-equilibrium properties of quantum many-body systems in the framework of exactly solvable quantum field theory in one spatial dimension. Specific systems include interacting fermions described by the Luttinger model and effective descriptions of spin chains using conformal field theory (CFT). Special emphasis is placed on heat and charge transport, studied from the point of view of quench dynamics, and, in particular, the effects of breaking conformal symmetries on transport properties. Examples include the Luttinger model with non-local interactions, breaking Lorentz and scale invariance, and inhomogeneous CFT, which generalizes standard CFT in that the usual propagation velocity v is replaced by a function v(x) that depends smoothly on the position x, breaking translation invariance.

    The quench dynamics studied here is for quantum quenches between, in general, different smooth inhomogeneous systems. An example of this is the so-called smooth-profile protocol, in which the initial state is defined by, e.g., smooth inhomogeneous profiles of inverse temperature and chemical potential, and the time evolution is governed by a homogeneous Hamiltonian. Using this protocol, we compute exact analytical results for the full time evolution of the systems mentioned above. In particular, we derive finite-time results that are universal in the sense that the same relations between the non-equilibrium dynamics and the initial profiles hold for any unitary CFT. These results also make clear that heat and charge transport in standard CFT are purely ballistic.

    Finally, we propose and study an inhomogeneous CFT model with v(x) given by a random function. We argue that this model naturally emerges as an effective description of one-dimensional quantum many-body systems with certain static random impurities. Using tools from wave propagation in random media, we show that such impurities lead to normal and anomalous diffusive contributions to heat transport on top of the ballistic one known from standard CFT.

  • Lu, Ke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Wearable Solutions for P-Health at Work: Precise, Pervasive and Preventive2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With a demographic change towards an older population, the structure of the labor force is shifting, and people are expected to work longer within their extended life span. However, for many people, wellbeing has been compromised by work-related problems before they reach the retirement age. Prevention of chronic diseases such as cardiovascular diseases and musculoskeletal disorders is needed to provide a sustainable working life. Therefore, pervasive tools for risk assessment and intervention are needed. The vision is to use wearable technologies to promote a sustainable work life, to be more detailed, to develop a system that integrates wearable technologies into workwear to provide pervasive and precise occupational disease prevention. This thesis presents some efforts towards this vision, including system-level design for a wearable risk assessment and intervention system, as well as specific insight into solutions for in-field assessment of physical workload and technologies to make smart sensing garments. The overall system is capable of providing unobtrusive monitoring of several signs, automatically estimating risk levels and giving feedback and reports to different stakeholders. The performance and usability of current energy expenditure estimation methods based on heart rate monitors and accelerometers were examined in occupational scenarios. The usefulness of impedance pneumography-based respiration monitoring for energy expenditure estimation was explored. A method that integrates heart rate, respiration and motion information using a neuronal network for enhancing the estimation is shown. The sensing garment is an essential component of the wearable system. Smart textile solutions that improve the performance, usability and manufacturability of sensing garments, including solutions for wiring and textile-electronics interconnection as well as an overall garment design that utilizes different technologies, are demonstrated.

  • Gedik, Ali Cenk
    et al.
    Department of Musicology, Dokuz Eylül University.
    Holzapfel, André
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    The Meaning of Music in Ethnomusicology and Music Information Retrieval: Obstacles Against Computational Ethnomusicology2018Conference paper (Refereed)