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  • Public defence: 2017-09-27 13:00 Ka-Sal C (Sal Sven-Olof Öhrvik), Kista
    Laya, Andrés
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    The Internet of Things in Health, Social Care, and Wellbeing2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) enables opportunities to remotely sense and control objects via communication networks. We study services based on connected devices and the collaboration they generate between the ICT and the Health, Social Care and Wellbeing (HSCWB) industries.

    In HSCWB, IoT can support a change from episodic treatments of illness to preventive care and wellbeing solutions. The IoT can be a supporter in cost efficient and high quality health care. The objective is to achieve healthier life years and more efficiency in health and social care. Even if the potential of IoT in HSCWB has been proven in pilot projects and small-scale solutions, the benefits and opportunities for many actors are still unclear. There is a research gap in studying the roles and business opportunities for market-driven technology-based solutions enabled by connected devices.

    The research approach separates technological and business domains. On the technology side, the focus is on advances in connectivity for IoT. We present the technical details on a limitation to support IoT devices in cellular networks. We quantify the limitations in the Random Access Channel of the LTE air interface to support IoT devices. Moreover, we propose the adaptation of an access mechanism to enable massive number of simultaneous access attempt in cellular networks.

    On the business side, we identify and present how the conditions of the health and social care structure in Sweden affect the establishment of IoT solutions in HSCWB. We then show how these conditions have generated three distinctive development patterns—to innovate within the public sector, to develop solutions in the private care sector, or to target the wellbeing sector to avoid regulatory setbacks.

    Based on these patterns, we look closer into study cases to show how business opportunities have been addressed from a business network perspective. When deploying an IoT service, not all critical challenges can be appreciated at a single firm level. Therefore, we rely on a network-level business model framework to analyze emerging IoT services in HSCWB.

    The findings suggest that IoT components can improve an existing service by automating internal working processes, or they can enable new value propositions and convenience to end users. In general terms, the collaboration can be used (i) to improve the efficiency of existing services in health and social care without an original intention to change the service offering, or (ii) to create novelty and differentiation, without affecting the internal logics of existing HSCWB services.

  • Public defence: 2017-09-29 09:15 R1, Stockholm
    Wiklund, Jenny
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Critical Studies in Architecture.
    Journal - rekonstruktion av kropp och minne2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The project was developed in co-operation between Jenny Wiklund and KTH, Uppsala University Hospital, Uppsala University, Karolinska Institute, Royal Institute of Art, Aarhus School of Architecture, and curator Jan Åman.

    The project was developed sculpturally at the Royal Institute of Art. Preliminary studies of medicine were made at Karolinska University Hospital. The final study combines studies at Uppsala University Hospital of three-dimensional visualization of medical imaging with studies of clinical anatomy at Uppsala University, to be amalgamated to a sculptural interpretation and production.

    R1, the Reactor Hall, is staged as a site-specific monumental artistic work. The installation provides a temporary coat around the chapters of the dissertation exhibition, dealing with body and brain. The exhibition tells us about a specific moment, there is no memory, nor proprioception. There is no history, nor future.

    Through the exhibition an understanding of the connection between theoretical thinking and visual interpretation emerges. It is research by artistic and architectonic precision with references to art, architecture, medicine and medical technique. References come from concrete objects in concrete rooms, from specific artistic work of individual artists and from auscultating a number of expert presentations, where people by presence conveyed their knowledge.

    Architecture is a spatial construction of identity, here in the form of an exhibition as temporary visual spatial-aesthetic poetic theory. The form of the dissertation was chosen due to the main subject investigated, memory, and its temporary reshaping of the room at each specific point of time it is aroused. The visual impression come before all other descriptions, logical to the event that preceded the subject of the project, a loss of memory, when the experience of the room came before the language, the body before the brain, trained memories in the form of figures before an autobiography.

  • Public defence: 2017-09-29 10:00 Kollegiesalen, Stockholm
    H. Moud, Pouya
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Catalytic Conversion of Undesired Organic Compounds to Syngas in Biomass Gasification and Pyrolysis Applications2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Reliable energy supply is a major concern and crucial for development of the global society. To address the dependency on fossil fuel and the negative effects of this reliance on climate, there is a need for a transition to cleaner sources. An attractive solution for replacing fossil-based products is renewable substitutes produced from biomass. Gasification and pyrolysis are two promising thermochemical conversion technologies, facing challenges before large-scale commercialization becomes viable. In case of biomass gasification, tar is often and undesired by-product. An attractive option to convert tar into syngas is nickel-based catalytic steam reforming (SR). For biomass pyrolysis, catalytic SR is in early stages of investigation as a feasible option for bio-crude conversion to syngas.

    The focus of the thesis is partly dedicated to describe research aimed at increasing the knowledge around tar reforming mechanisms and effect of biomass-derived impurities on Ni-based tar reforming catalyst downstream of gasifiers. The work focuses on better understanding of gas-phase alkali interaction with Ni-based catalyst surface under realistic conditions. A methodology was successfully developed to enable controlled investigation of the combined sulfur (S) and potassium (K) interaction with the catalyst. The most striking result was that K appears to lower the sulfur coverage and increases methane and tar reforming activity. Additionally, the results obtained in the atomistic investigations are discussed in terms of naphthalene adsorption, dehydrogenation and carbon passivation of nickel.

    Furthermore, the thesis describes research performed on pyrolysis gas pre-conditioning at a small-industrial scale, using an iron-based catalyst. Findings showed that Fe-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way for generating a hydrogen-enriched gas without the need for bio-crude condensation.

  • Public defence: 2017-09-29 10:00 Gladan, Stockholm
    Alemani, Mattia
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Particle emissions from car brakes: The influence of contact conditions on the pad-to-rotor interface2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale.

    Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissions

    Paper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified.

    Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels.

    Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified.

    Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities.

    Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands.

    Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.

  • Public defence: 2017-09-29 10:00 E3, Stockholm
    Volk, Anna-Luisa
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Cell line and protein engineering tools for production and characterization of biologics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Our increasing understanding of disease mechanisms coupled with technological advances has facilitated the generation of pharmaceutical proteins, which are able to address yet unmet medical needs. Diseases that were fatal in the past can now be treated with novel biological medications improving and prolonging life for many patients. Pharmaceutical protein production is, however, a complex undertaking, which is by no means problem-free. The demand for more complex proteins and the realization of the importance of post-translational modifications have led to an increasing use of mammalian cells for protein expression. Despite improvements in design and production, the costs required for the development of pharmaceutical proteins still are far greater than those for conventional, small molecule drugs. To render such treatments affordable for healthcare suppliers and assist in the implementation of precision medicine, further progress is needed. In five papers this thesis describes strategies and methods that can help to advance the development and manufacturing of pharmaceutical proteins. Two platforms for antibody engineering have been developed and evaluated, one of which allows for efficient screening of antibody libraries whilst the second enables the straightforward generation of bispecific antibodies. Moreover, a method for epitope mapping has been devised and applied to map the therapeutic antibody eculizumab’s epitope on its target protein. In a second step it was shown how this epitope information can be used to stratify patients and, thus, contribute to the realization of precision medicine. The fourth project focuses on the cell line development process during pharmaceutical protein production. A platform is described combining split-GFP and fluorescence-activated droplet sorting, which allows for the efficient selection of highly secreting cells from a heterogeneous cell pool. In an accompanying study, the split-GFP probe was improved to enable shorter assay times and increased sensitivity, desirable characteristics for high-throughput screening of cell pools. In summary, this thesis provides tools to improve design, development and production of future pharmaceutical proteins and as a result, it makes a contribution to the goal of implementing precision medicine through the generation of more cost-effective biopharmaceuticals for well-characterized patient groups.

  • Public defence: 2017-09-29 10:00 F3 (rumsnr: 132), Stockholm
    Halldin Stenlid, Joakim
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden.

    In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface.

    An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces.

    Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology.

  • Public defence: 2017-09-29 10:00 Kollegiesalen, Stockholm
    Fischer, David
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Integrating Heat Pumps into Smart Grids2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transforming our energy system towards 100% renewable energy sources requires radical changes across all energy sectors. Heat pumps as efficient heat generation technology link the electricity and heat sector. From 2010 to 2015 between 750,000 and 800,000 heat pumps have been sold every year across Europe. Those heat pumps, when connected to thermal storage or using the buildings’ thermal inertia, have the potential to offer demand flexibility to the power system. In a renewable, interconnected and to a large extend decentralised energy system - the smart grid - heat pumps can be operated according to the need of the electric power system. This might impact heat pump system design, controls and operation, which is investigated in this thesis. The main objective of this thesis is to add knowledge and suggest methods to facilitate the transition towards a renewable and smart energy system, in which heat pump systems and their flexibility are used and designed in an optimal way. Therefore this thesis investigates the integration of heat pumps in a smart grid on three different system boundary levels. On each boundary level the focus is on different aspects and different methods are used. On the highest boundary level, the integration of heat pumps into a smart grid and the resulting requirements for heat pump system design are studied. Results of a literature study show, that currently discussed applications of heat pumps in a smart grid focus on the provision of ancillary services, the integration of renewable energy sources, and the operation under time variable electricity prices. Integrating heat pumps into the power system can be achieved by direct, indirect and agent based control strategies. The next level of investigation covers the aggregation of heat pumps into pools. For this purpose a stochastic bottom-up model for heat pump pools has been developed. This model accounts for the diversity of buildings, heat pump systems and occupants. Results of a simulation study of a heat pump pool highlight the fact that flexibility of heat pumps is not constant and is changing during the course of the day and year. A characteristic response of a heat pump pool towards direct load control signals is identified and shows three characteristic phases 1) charging/ activation phase, 2) steady state phase, 3) discharging/regeneration phase. It is found that the duration of the control signal and the load shift strategy implemented in the heat pump systems are decisive for flexibility. Further it is shown that flexibility might come at the cost of efficiency of the local heat pump systems. On the level of individual buildings this thesis explores to which extent the sizing of heat pumps, storage and back-up heater as well as system controls have to be adjusted when integrating heat pumps into a smart grid. Results of a structural optimisation study, targeting to minimise total cost of ownership, show that sizing of the heat pump unit and the electric back-up heater remain almost unchanged when PV and time variable electricity prices are introduced. However an increase in storage capacity is beneficial to profit from time variable prices or onsite photovoltaic (PV). It showed that the ways heat pumps and storages are sized in Germany today provided sufficient storage capacity for most of the investigated scenarios. Furthermore increasing storage leads to diminishing returns as investment costs and system losses increase with increasing storage size. This leads to the conclusion that local heat pump system efficiency as well as flexibility requirements of the power system should be considered, when designing heat pump systems. Improving the controls shows great potential for increasing heat pump system efficiency, reducing operation cost and scheduling heat pump operation along to match the requirements from the power system. A dynamic building simulation study, where rule-based, predictive rule-based and model predictive control approaches were compared, reveals that the use of model predictive controls can reduce annual electricity cost and increase PV self-consumption significantly, compared to tailored rule-based and predictive rule-based control approaches. When deciding upon a control strategy the following should be taken into account: complexity of design, robustness against changes in external conditions and computational resources. It is shown that operating heat pumps in a smart grid changes operating hours, temperatures, on/off cycles and seasonal performance compared to today’s heatdriven operation. It is shown that the goals to reduce operating cost, maximise system efficiency or increase PV self-consumption can be conflicting and are often impossible to achieve simultaneously. Not necessarily will operation in a smart grid increase the efficiency of individual systems, rather offers the possibility to increase efficiency of the overall energy system. It is found that sizing, controls and use-case are interconnected and should be considered simultaneously in the design process of heat pump systems. A goal for future research should be the design of optimum flexible heat pump systems, where the heat pump unit, the building, the hydraulic system, heat distribution, storage and controls are designed optimally for the flexibility requirements of both the end-users and the power system.

  • Public defence: 2017-09-29 10:00 Sal V1, Stockholm
    Zuo, Minyu
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Enhanced phosphorus removal from wastewater using virgin and modified slags: performance, speciation and mechanisms2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Argon oxygen decarburization slag (AOD) was tested in batch and column experiments to investigate its phosphorus (P) removal performance. The effects of factors such as AOD dose, initial P concentration of the feeding solution, and aging on the P removal ability of the slags were analyzed. In a column experiment, electric arc furnace slag (EAF), blast furnace slag (BFS) and AOD were combined in five different ways to determine optimal conditions for P removal. In another column experiment, the three types of slag were modified with polyethylene glycol (PEG) and NaOH to adjust their dissolution properties and the effect on P removal performance was examined. In the batch experiments, AOD exhibited very promising P removal ability. It removed 94.8% of P from 6.5 mg P L-1 synthetic solution in 4 hours with a dose of 5 g L-1. Maximum P removal capacity of 27.5 mg P g-1 was achieved. In the dual-filter column experiment, the column packed with only EAF had the best P removal performance (consistently above 93%). Amorphous calcium phosphate (ACP) was identified as the main P species in the five slag samples collected from the outlet chambers. The contributions from crystalline calcium phosphate (Ca-P) and P adsorbed on iron/aluminum (hydr)oxides were greater in samples from the inlet chambers. The P speciation results revealed that P was predominantly removed by the slags through formation of ACP. The second column experiment showed that modification with PEG and NaOH solution only enhanced short-term P removal by the slags. However, exhaustion of the modified slags occurred much earlier, indicating that the modification process had shortened the lifespan of the slags. Untreated AOD showed better P removal than untreated EAF until pore volume 244, probably due to faster dissolution rate of gamma dicalcium silicate (dominating in AOD according to the XRD results) than of beta dicalcium silicate (dominating in EAF).

  • Public defence: 2017-09-29 10:00 Sal B, Kista
    Pan, Fan
    KTH, School of Engineering Sciences (SCI).
    A theoretical study of magnetism and its extension to finite temperatures in random alloys2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This work presents new theoretical developments of atomistic spin simulations of magnetic materials at finite temperatures. Special focus is put on the description of longitudinal magnetic fluctuations and the application in random transition metal alloys. A new computational scheme is proposed for mapping total energies from electronic structure calculations to an extended atomistic spin model. The proposed model has some new appealing features from previous models. To be more specific, the proposed model successfully eliminates the reference state dependency of the mapping that previous models have suffered from. Moreover, the proposed model includes longitudinal magnetic fluctuations that gives an improved description of the magnetic properties over a larger temperature interval. The proposed model strives to find the right compromise between accuracy and computational feasibility and it is applied not only to the elemental systems Fe, Co and Ni, but also to a number of binary transition metal alloys such as Permalloy (Fe$_{20\%}$Ni$_{80\%}$) and Fe-Co systems.

    Electronic structure calculations of Gilbert damping and the closely related magnetodynamic properties, the saturation magnetization and exchange stiffness, have been conducted for a number of different magnetic systems including Permalloy with additional doping of $4d$ or $5d$ transition metal impurities and the full Heusler alloy Co$_2$FeAl. Regarding the Permalloy based systems, a systematic study of the magnetodynamic properties was performed and compared with existing experimental data. In general we found good agreement and manage to explain the main trends regarding the Gilbert damping across the series with a simple model that captures the most important material properties to the damping, namely the spin orbit coupling and density of states at the Fermi level. In Co$_2$FeAl, we calculated the Gilbert damping in different existing crystal structures and compare those with new experimental data and found good agreement between them.

    Magnon properties of random alloys, like Permalloy, are studied using two complementory methods, the adiabatic magnon spectra valid at zero temperature and from finite temperature atomistic spin dynamics through the dynamical structure factor. The influence of chemical disorder and temperature effects on the magnon properties are investigated that hopefully could motivate new experimental studies of these materials.

  • Public defence: 2017-09-29 13:00 T1, Emmy Rappesalen, Huddinge
    Strömgren, Marcus
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Social capital in healthcare: A resource for sustainable engagement in organizational improvement work2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Social capital, work engagement, working conditions, and leadership are concepts that have been studied previously, but there is lack of knowledge about what processes promote sustainable organizational improvement work in hospitals, and specifically, what leads healthcare professionals to engage in clinical developments.

    The overall aim of this thesis is to increase knowledge of how social capital and engagement contribute to sustainable organizational improvement work in hospitals and how social capital and engagement are created during organizational improvement work. Data were collected by a questionnaire at three times over a period of two years at five hospitals and all studies are quantitative.

    The results show that improved working conditions and employees’ attitudes to engagement in improvement work are associated with and have importance for healthcare professionals’ work engagement and clinical engagement in improving care processes (Study I). Job demands, social capital, and other job resources are associated with healthcare professionals’ intention to leave their jobs, whereas high levels of social capital are associated with low levels of intention to leave (Study II). Increased social capital predicted healthcare professionals’ job satisfaction, work engagement, and engagement in patient safety (Study III). Leadership is shown to be important for healthcare professionals’ social capital, and levels of leadership quality correlate with levels of social capital over time (Study IV).

    In conclusion, social capital, increased job resources, and decreased job demands are important conditions for healthcare professionals’ engagement in organizational improvement work. To develop social capital, leadership quality is an important precondition. Social capital can be regarded as a resource for sustainable organizational improvement work in healthcare, because of its importance for healthcare professionals’ engagement, job satisfaction, and intention to leave.

  • Public defence: 2017-09-29 13:00 Ka-Sal A (Sal Östen Mäkitalo), Stockholm
    Hedayati, Raheleh
    KTH, School of Information and Communication Technology (ICT).
    High-Temperature Analog and Mixed-Signal Integrated Circuits in Bipolar Silicon Carbide Technology2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Silicon carbide (SiC) integrated circuits (ICs) can enable the emergence of robust and reliable systems, including data acquisition and on-site control for extreme environments with high temperature and high radiation such as deep earth drilling, space and aviation, electric and hybrid vehicles, and combustion engines. In particular, SiC ICs provide significant benefit by reducing power dissipation and leakage current at temperatures above 300 °C compared to the Si counterpart. In fact, Si-based ICs have a limited maximum operating temperature which is around 300 °C for silicon on insulator (SOI). Owing to its superior material properties such as wide bandgap, three times larger than Silicon, and low intrinsic carrier concentration, SiC is an excellent candidate for high-temperature applications. In this thesis, analog and mixed-signal circuits have been implemented using SiC bipolar technology, including bandgap references, amplifiers, a master-slave comparator, an 8-bit R-2R ladder-based digital-to-analog converter (DAC), a 4-bit flash analog-to-digital converter (ADC), and a 10-bit successive-approximation-register (SAR) ADC. Spice models were developed at binned temperature points from room temperature to 500 °C, to simulate and predict the circuits’ behavior with temperature variation. The high-temperature performance of the fabricated chips has been investigated and verified over a wide temperature range from 25 °C to 500 °C. A stable gain of 39 dB was measured in the temperature range from 25 °C up to 500 °C for the inverting operational amplifier with ideal closed-loop gain of 40 dB. Although the circuit design in an immature SiC bipolar technology is challenging due to the low current gain of the transistors and lack of complete AC models, various circuit techniques have been applied to mitigate these problems. This thesis details the challenges faced and methods employed for device modeling, integrated circuit design, layout implementation and finally performance verification using on-wafer characterization of the fabricated SiC ICs over a wide temperature range.

  • Public defence: 2017-09-29 13:00 Hall C, Kista
    Ivanov, Ruslan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The modern InGaN technology demonstrates high efficiencies only in the blue spectral region and low current operation modes. The growth of InGaN quantum wells (QWs) on nonbasal crystallographic planes (NBP) has potential to deliver high-power blue and green light emitting diodes and lasers. The emission properties of these QWs are largely determined by the localization of carriers in the minima of spatially inhomogeneous band potential, which affects the recombination dynamics, spectral characteristics of the emission, its optical polarization and carrier transport. Understanding it is crucial for increasing the efficiency of NBP structures to their theoretical limit.

    In this thesis, the influence of carrier localization on the critical aspects of light emission has been investigated in semipolar  and nonpolar  InGaN QWs. For this purpose, novel multimode scanning near-field optical microscopy configurations have been developed, allowing mapping of the spectrally-, time-, and polarization-resolved emission.

    In the nonpolar QW structures the sub-micrometer band gap fluctuations could be assigned to the selective incorporation of indium on different slopes of the undulations, while in the smoother semipolar QWs – to the nonuniformity of QW growth. The nanoscale band potential fluctuations and the carrier localization were found to increase with increasing indium percentage in the InGaN alloy. In spite to the large depth of the potential minima, the localized valence band states were found to retain properties of the corresponding bands. The reduced carrier transfer between localization sites has been suggested as a reason for the long recombination times in the green-emitting semipolar QWs. Sharp increase of the radiative lifetimes has been assigned to the effect of nanoscale electric fields resulting from nonplanar QW interfaces. Lastly, the ambipolar carrier diffusion has been measured, revealing ~100 nm diffusion length and high anisotropy.

  • Public defence: 2017-09-29 13:30 F3, Stockholm
    Mengiste, Simachew Abebe
    KTH, School of Computer Science and Communication (CSC).
    Computational Approaches to the Degeneration of Brain Networks and Other Complex Networks2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Networks are ubiquitous with several levels of complexity, configuration, hierarchy and function. Many micro- and macro-scale biological or non-biological interactions define complex systems. Our most sophisticated organ, the brain, accommodates the interaction of its billions of neurons through trillions of synapses and is a good example of a complex system. Network structure has been shown to be the key to determine network functions. For instance, communities or modules in the network explain functional segregation and modular interactions reveal functional integration. Moreover, the dynamics of cortical networks have been experimentally shown to be linked to the behavioral states of the animal. The level of rate and synchrony have been demonstrated to be related to sleep (inactive) and awake (active) states of animals. The structure of brain networks is not static. New synapses are formed and some existing synapses or neurons die due to neurodegenerative disease, environmental influences, development and learning, etc. Although there are many studies on the function of brain networks, the changes by neuronal and synaptic degeneration have not been so far in focus. In fact, there is no known mathematical model on the progressive pattern of synaptic pruning and neurodegeneration. The goal of this dissertation is to develop various models of progressive network degeneration and analyze their impact on structural and functional features of the networks. In order to expand the often chosen approach of the "random networks", the "small world" and "scale-free" network topologies are considered which have recently been proposed as alternatives. The effect of four progressive synaptic pruning strategies on the size of critical sites of brain networks and other complex networks is analyzed. Different measures are used to estimate the levels of population rate, regularity, synchrony and pair-wise correlation of neuronal networks. Our analysis reveals that the network degree, instead of network topology, highly affects the mean population activity. 

    The full text will be freely available from 2017-10-02 08:00
  • Public defence: 2017-10-02 10:00 F3, KTH, Stockholm
    Nazari, Mohammad
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Control and Planning of Multi-Terminal HVDC Transmission Systems2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    With recent advances in power electronic technology, high-voltage direct current (HVDC) transmission system has become an alternative for transmitting power, especially over long distances. Multi-terminal HVDC (MTDC) systems are proposed as HVDC systems with more than two terminals. In addition, the wind is becoming one of the most important sources of renewable energy in the world, with vast sources available in offshore areas. MTDC systems are attractive solutions for connecting offshore wind farms to AC grids.

     

    This thesis discusses three scopes of MTDC systems: primary control, secondary control, and AC-DC transmission expansion planning. 

    In the primary control part, sliding mode control and multi-agent control are proposed. The sliding mode control can control the system fast and with very small overshoot and compared to proposed methods in the literature, it is less sensitive to changes in parameters. In the proposed multi-agent control strategy, we aim to find a solution for the problems caused by lack of global signal in the control of MTDC systems.

     

    In the secondary control part, we propose a controller, based on multi-agent systems, which follows the variations of wind and minimize the DC transmission and conversion losses, while considering the price of energy in each AC system and the scheduled injected power to each AC grid. The controller operates in both centralized and distributed modes.

    In the expansion planning part, we aim to propose a methodology to determine the optimal configuration of the MTDC system. The goal is to maximize the transferred power from the wind farms to the onshore grids while minimizing the investment cost. We propose a two-stage mixed-integer second order cone program (MISOCP) for optimal expansion of both DC and AC networks. The two-stage MISOCP is solved using the parallelized Benders decomposition algorithm.

    The full text will be freely available from 2017-10-01 09:09
  • Public defence: 2017-10-06 10:00 Ka-Sal A (Sal Östen Mäkitalo) KTH, Kista
    Tian, Ye
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    SiC Readout IC for High Temperature Seismic Sensor System2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Over the last decade, electronics operating at high temperatures have been increasingly demanded to support in situ sensing applications such as automotive, deep-well drilling and aerospace. However, few of these applications have requirements above 460 °C, as the surface temperature of Venus, which is a specific target for the seismic sensing application in this thesis. Due to its wide bandgap, Silicon Carbide (SiC) is a promising candidate to implement integrated circuits (ICs) operating in such extreme environments. In this thesis, various analog and mixed-signal ICs in 4H-SiC bipolar technology for high-temperature sensing applications are explored, in which the device performance variation over temperatures are considered. For this purpose, device modeling, circuit design, layout design, and device/circuit characterization are involved.

    In this thesis, the circuits are fabricated in two batches using similar technologies. In Batch 1, the first SiC sigma-delta modulator is demonstrated to operate up to 500 °C with a 30 dB peak SNDR. Its building blocks including a fully-differential amplifier, an integrator and a comparator are characterized individually to investigate the modulator performance variation over temperatures. In the succeeding Batch 2, a SiC electromechanical sigma-delta modulator is designed with a chosen Si capacitive sensor for seismic sensing on Venus. Its building blocks including a charge amplifier, a multiplier and an oscillator are designed. Compared to Batch 1, a smaller transistor and two metal-interconnects are used to implement higher integration ICs in Batch 2. Moreover, the first VBIC-based compact model featured with continuous-temperature scalability from 27 to 500 °C is developed based on the SiC transistor in Batch 1, in order to optimize the design of circuits in Batch 2. The demonstrated performance of ICs in Batch 1 show the feasibility to further develop the SiC readout ICs for seismic sensor system operating on Venus.

  • Public defence: 2017-10-06 10:00 Air & Fire, Solna
    Zandian, Arash
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Array-based Autoantibody Profiling and Epitope Mapping2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Antibodies are a class of proteins that are made by the immune system to recognize harmful organisms and molecules. Their exceptional capability of specifically recognizing molecules has been investigated for over a century and information thereof has been utilized for a variety of applications including vaccine and generation of therapeutic antibodies. Occasionally, instead of protecting the host against pathogens, antibodies can recognize constituents of the host and thereby cause an autoimmune reaction that eventually can lead to a disease. Therefore, it is of great interest to understand what the antibodies bind to and their specificities.

     

    The last decades of technical development and availability of protein and peptide microarrays have enabled large-scale profiling of antibodies and precise determination of their specificities through epitope mapping. In this thesis the aim was to use affinity proteomics tools to profile antibodies, determine their specificities, and discover potential associations of autoantigens to disease by analyzing blood-derived samples with microarray-based methods.

     

    In Paper I, 57 serum samples from patients with the suggested autoimmune disease narcolepsy, were analyzed on planar antigen microarrays with 10,846 human protein fragments. Verification on an independent sample collection consisting of serum samples from 176 individuals, revealed METTL22 and NT5C1A as two potential autoantigens. In Paper II, antibodies from 53 plasma samples from patients with first-episode psychosis, a condition suggested to have a partial autoimmune component, were analyzed on planar antigen microarrays with 2,304 human protein fragments. After a follow-up study of the patients, antibodies toward an antigen representing the three proteins, PAGE2, PAGE2B, PAGE5, was found associated to an increased risk of developing schizophrenia. In Paper III, serum and plasma samples from patients with the autoimmune diseases multiple sclerosis and narcolepsy, were epitope mapped on high-density peptide microarrays with approximately 2.2 million peptides. Technical and biological verification, by using other microarray technology and analyzing  samples from 448 patients, revealed one peptide for multiple sclerosis and narcolepsy, representing the proteins MAP3K7 and NRXN1, with higher antibody reactivity towards in each group, respectively. In Paper IV, purified polyclonal antibodies raised against a surface antigen found on malaria-infected erythrocytes, were profiled on the peptide microarrays representing all proteins found on malaria-infected erythrocytes derived from Plasmodium falciparum. Then, different Plasmodium falciparum strains were analyzed by immunofluorescence microscopy and western blots, using the epitope mapped antibodies. The performance of the immunoassays were compared to the identified epitopes, and validated by RNA sequencing.

     

    In conclusion, these investigations describe multiplex methods to identify and characterize antibodies, their disease association and epitopes. Follow-up studies are needed to determine their potential use and clinical value.

  • Public defence: 2017-10-06 10:00 Kollegiesalen, Stockholm
    Shahkarami, Pirouz
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Solute Transport in Fractured Rocks: The Effect of Stagnant Water Zones and Velocity Dispersion2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The focus of this thesis is on the development of new models to improve our understanding of radionuclide transport in the repository “far-field” in fractured rocks. The proposed models contribute to the channel network concept and describe the recently developed models with stagnant water zones (STWZs) and channels with variable aperture allowing to consider their possible impacts on the overall transport of radionuclides in fractured rocks. New conceptual models are also proposed to better understand hydrodynamic dispersion in fractured rocks by taking into account velocity distribution within tapered channels, i.e., Fickian-type dispersion, and between different flow paths, i.e., velocity dispersion, as embodied in the proposed multi-channel model.

    The results of both deterministic and probabilistic analyses reveal that over the long times of interest for safety assessment of high-level radioactive waste repositories, STWZs can substantially enhance the retardation of both short- and long-lived nuclides, with the exception of the non-sorbing species, i.e., 36Cl and 129I. Nevertheless, over the short time-scales the impact of STWZs is not very strong and is not expected to affect the results of short-term field experiments. It is also shown that the proposed multi-channel model can explain the apparent scale dependency of the dispersion coefficient that is often observed in tracer experiments. It is further discussed that the interpreted results of short-range tracer experiments cannot necessarily give information on what would take place over longer distances because the spreading mechanisms are expected to be entirely different. Usefulness of the continuum model to interpret tracer experiments is, thereafter, discussed and arguments are presented to support the premise that it is more physically meaningful to describe flow and transport as taking place in a three-dimensional network of channels.

    The full text will be freely available from 2018-10-08 14:00
  • Public defence: 2017-10-06 13:00 F3, Stockholm
    Andersson, Ken G.
    KTH, School of Biotechnology (BIO), Protein Technology.
    Combinatorial Protein Engineering Of Affibody Molecules Using E. Coli Display And Rational Design Of Affibody-Based Tracers For Medical Imaging2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Directed evolution is today an established strategy for generation of new affinity proteins. This thesis describes the development of a cell-display method using Escherichia coli for directed evolution of Affibody molecules. Further, the thesis describes rational design of Affibody-based tracers, intended for future patient stratification using medical imaging. Fusing recombinant proteins to various autotransporters is a promising approach for efficient surface display on the surface of E. coli, as well as for construction of high-complexity libraries. In paper I, we successfully engineered an expression vector for display of Affibody molecules using the autotransporter AIDA-I. In paper II, a large Affibody library of 2.3x109 variants was constructed and screening using FACS resulted in new specific binders in the nanomolar range. In paper III, we demonstrated Sortase-mediated secretion and conjugation of binders directly from the E. coli surface. 

    The three following studies describe rational design of Affibody-based tracers against two cancer-associated targets for molecular imaging. First, anti-HER3 Affibody molecules were labelled with 111In, and SPECT imaging showed that the conjugates specifically targeted HER3-expressing xenografts. Furthermore, labeling with 68Ga for PET imaging showed that tumor uptake correlated with HER3 expression, suggesting that the tracers have potential for patient stratification. The last study describes the development and investigation of anti-EGFR Affibody-based imaging agents. Labeled with 89Zr, the Affibody tracer demonstrated higher tumor uptake at 3 h post injection than the anti-EGFR antibody cetuximab at 48 h post injection. 

    In conclusion, this thesis describes new tools and knowledge that will hopefully contribute to the development of affinity proteins for biotechnology, therapy and medical imaging in the future. 

     

  • Public defence: 2017-10-06 14:00 Kollegiesalen, Stockholm
    Andersen, Kristina
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Making Magic Machines2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    How can we design experiences that explore ideas and notions of the unknown? The aim of the work outlined here is to create short, intense, workshop-like experiences that generate strong commitments, and expose underlying personal desires as drivers for new ideas. I would like to propose a material practice, which uses open-ended making to engage in the imagination of new things. Informed by a concern or a longing, this exploration employs familiar yet mundane materials - such as candy and cardboard - through which several planes collide: the possible, the unknown, the feared and the desired. The process is aimed at allowing a broad range of knowledge to materialise - through ways that are less normative, and less constrained by commercial and technological concerns, and to emerge instead as far-fetched ideas that offer a kind of knowledge, which belongs to no one. The format has evolved over time, from relatively elaborate workshops for technology prototyping, towards the point where they are now focussed on the making of work that is about technology, rather than of technology.

  • Public defence: 2017-10-09 10:00 Sal F3, Stockholm
    Poppi, Stefano
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Solar heat pump systems for heating applications: Analysis of system performance and possible solutions for improving system performance2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Solar heat pump systems (SHPs) are systems that combine solar energy and heat pumps. SHPs have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many solar thermal heat pump systems have become market-available in recent years; however these systems are still not widely employed in the residential sector. This is due mainly to the high initial costs (investment and installation costs) of solar thermal heat pump systems, which limits their cost-effectiveness. Enhancing cost-effectiveness of solar thermal heat pump systems is necessary for a more effective and broader market penetration.

    In this thesis, solar thermal and photovoltaic systems combined with heat pumps for heating applications are treated. The overall aims of the thesis are to: 1) investigate techno-economics of SHPs and 2) investigate possible solutions for improving system performance of a reference solar thermal and heat pump system for residential heating applications.

    In the first part of the thesis, the influence of climatic boundary conditions on economic performance of SHPs has been investigated by means of: a) an economic comparison of SHPs found in the relevant literature and b) system simulations of the reference solar thermal heat pump system.

    In the second part of the thesis, potential solutions for improving system performance of the reference solar thermal heat pump system with limited change in system’ costs are investigated. A systematic approach was used for investigating cost-effectiveness of the system improvements in the reference system.

    Based on results of the cost-effectiveness analysis, some of the investigated system improvements were chosen for being included in the design of a novel solar thermal and air source heat pump system concept. The novel system was designed for a house standard with relatively high operating temperatures (55°C/45°C) in the space heating distribution system and for high space heating demand (123 kWh/m2·year). Finally, the thesis ends with a cost-effectiveness analysis of the novel system.

  • Public defence: 2017-10-11 13:00 F3, Stockholm
    Rios, Felix Leopoldo
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Bayesian inference in probabilistic graphical models2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consists of four papers studying structure learning and Bayesian inference in probabilistic graphical models for both undirected and directed acyclic graphs (DAGs).

    Paper A presents a novel algorithm, called the Christmas tree algorithm (CTA), that incrementally construct junction trees for decomposable graphs by adding one node at a time to the underlying graph. We prove that CTA with positive probability is able to generate all junction trees of any given number of underlying nodes. Importantly for practical applications, we show that the transition probability of the CTA kernel has a computationally tractable expression. Applications of the CTA transition kernel are demonstrated in a sequential Monte Carlo (SMC) setting for counting the number of decomposable graphs.

    Paper B presents the SMC scheme in a more general setting specifically designed for approximating distributions over decomposable graphs. The transition kernel from CTA from Paper A is incorporated as proposal kernel. To improve the traditional SMC algorithm, a particle Gibbs sampler with a systematic refreshment step is further proposed. A simulation study is performed for approximate graph posterior inference within both log-linear and decomposable Gaussian graphical models showing efficiency of the suggested methodology in both cases.

    Paper C explores the particle Gibbs sampling scheme of Paper B for approximate posterior computations in the Bayesian predictive classification framework. Specifically, Bayesian model averaging (BMA) based on the posterior exploration of the class-specific model is incorporated into the predictive classifier to take full account of the model uncertainty. For each class, the dependence structure underlying the observed features is represented by a distribution over the space of decomposable graphs. Due to the intractability of explicit expression, averaging over the approximated graph posterior is performed. The proposed BMA classifier reveals superior performance compared to the ordinary Bayesian predictive classifier that does not account for the model uncertainty, as well as to a number of out-of-the-box classifiers.

    Paper D develops a novel prior distribution over DAGs with the ability to express prior knowledge in terms of graph layerings. In conjunction with the prior, a stochastic optimization algorithm based on the layering property of DAGs is developed for performing structure learning in Bayesian networks. A simulation study shows that the algorithm along with the prior has superior performance compared with existing priors when used for learning graph with a clearly layered structure.

  • Public defence: 2017-10-12 09:00 F3, Stockholm
    Lundgren, Anna
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    The Openness Buzz: A Study of Openness in Planning, Politics and Political Decision-Making in Sweden from an Institutional Perspective2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In today’s society of increased globalization and digitalization openness has become a buzzword. This raises questions about what we mean by openness and how it is interpreted in various contexts. This thesis has two aims; to explore how openness is interpreted in planning, politics and political decision-making, and to develop an analytical tool to assess openness in different contexts. A new institutional theory framework that centers on the interplay between institutions and actors has been used, and three empirical case studies in a Swedish context were conducted to analyze how openness is interpreted in planning in metropolitan regions, in politics through the political parties and in political decision-making in the Stockholm region. The research concludes that openness in planning, politics and political decision-making is interpreted along two inter-linked narrative lines: ’openness to people’ and ’openness to knowledge, information and ideas’. It was more common to talk about peoples’ accessibility to public services and participation in different parts of society (’openness to people’) than to talk about issues of transparency and ’openness to knowledge, information and ideas’. The institutional framework shows how openness is interpreted at different institutional levels. To what degree openness is expressed at different institutional levels vary by context. In planning for instance, openness is mainly interpreted in terms of governance, whereas in politics and political decision-making, openness is interpreted in an inter-play between culture and norms, institutions, governance and practice. The institutional framework complementary context-specific theories and elaborated into an analytical model, was found useful to explain what mechanisms are at play when dealing with openness in planning, politics and political decision-making, and can be applicable in future research of openness in other geographical or organizational contexts.

  • Public defence: 2017-10-12 10:00 Kollegiesalen, Stockholm
    Li, Bing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Impact Evaluation of Intentional Electromagnetic Interference (IEMI) on Targeted Loads in Complex Networks Using Analytical Investigations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With the proliferation of various electronic and electrical devices, IEMI has become a critical issue that may severely threaten the modern society. For practical protection considerations, it is crucial to comprehensively evaluate the potential damages resulted by IEMI. The major objective of this thesis is to study the impacts of IEMI on the targeted load in complex networks. More exactly, with respect to certain IEMI, the characteristics of the resulting frequency response on the targeted load are studied, and the effects of network configurations, i.e., the attribute of load impedances, lengths of lines, parameters of disturbance source, location of source and network structures, are also investigated.

    First, we developed a novel efficient method to solve the frequency response, which is applicable for arbitrary networks. The key idea is decomposing the whole complex network into multiple equivalent units, and performing a recursive approach to efficiently compute the frequency response without losing the precision.

    Subsequently, we studied the periodicity of the load response in the frequency domain. Starting with a simple network, we derived and verified the period of the frequency response. During the study, the periodicity with respect to load and media was discussed.

    Furthermore, with respect to five important time-domain norms, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change, and peak time integral of the pulse, we considered a parameterized ultra-wideband (UWB) transient as the disturbance source, and thoroughly studied its impacts on the targeted load regarding network configurations, which include load impedance, the lengths of lines and parameters of the UWB transient.

    Finally, we adopted a statistical approach to investigate the receptivity at the targeted load in a network. Via complementary cumulative distribution function, the stochastic IEMI and its effects on the targeted load were studied. Moreover, by statistical approach, we also investigated how the network structure affects the frequency response of the targeted load. The results give suggestions on how to protect the targeted load by varying network structures.

  • Public defence: 2017-10-13 10:00 Kollegiesalen, Stockholm
    Bastian, Anne
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Explaining Trends in Car Use2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Many western countries have seen a plateau and subsequent decline in car travel during the early 21st century. What has generated particular interest and debate is the claim that the development cannot only be explained by changes in traditional explanatory factors such as GDP, fuel prices and land-use. Instead, it has been argued, the observed trends are indications of substantial changes in lifestyles, preferences and attitudes to car travel and thus, not just a temporary plateau but a true peak in car use.

    This thesis is a compilation of five papers, studying the issue on a national, international, regional and city scale through quantitative analysis of aggregate administrative data and individual travel survey data. It concludes that the aggregate development of car travel per capita can be explained fairly well with the traditional model variables GDP and fuel price. Furthermore, this thesis shows that spatial context and policy become increasingly important in car use trends: car use diverges over time between city, suburban and rural residents of Sweden and other European countries, while gender and to some extent income become less differentiating for car use.

  • Public defence: 2017-10-13 13:00 F3, Stockholm
    Lindholm, Love
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Numerical Analysis, NA.
    Numerical methods for the calibration problem in finance and mean field game equations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis contains five papers and an introduction. The first four of the included papers are related to financial mathematics and the fifth paper studies a case of mean field game equations. The introduction thus provides background in financial mathematics relevant to the first four papers, and an introduction to mean field game equations related to the fifth paper.

    In Paper I, we use theory from optimal control to calibrate the so called local volatility process given market data on options. Optimality conditions are in this case given by the solution to a Hamiltonian system of differential equations. Regularization is added by mollifying the Hamiltonian in this system and we solve the resulting equation using a trust region Newton method. We find that our resulting algorithm for the calibration problem is both accurate and robust.

    In Paper II, we solve the local volatility calibration problem using a technique that is related to - but also different from - the Hamiltonian framework in Paper I. We formulate the optimization problem by means of a Lagrangian multiplier and add a Tikhonov type regularization directly on the parameter we are trying to estimate. The resulting equations are solved with the same trust region Newton method as in Paper II, and again we obtain an accurate and robust algorithm for the calibration problem.

    Paper III formulates the problem of calibrating a local volatility process to option prices in a way that differs entirely from what is done in the first two papers. We exploit the linearity of the Dupire equation governing the prices to write the optimization problem as a quadratic programming problem. We illustrate by a numerical example that method can indeed be used to find a local volatility that gives good match between model prices and observed market prices on options.

    Paper IV deals with the hedging problem in finance. We investigate if so called quadratic hedging strategies formulated for a stochastic volatility model can generate smaller hedging errors than obtained when hedging with the standard Black-Scholes framework. We thus apply the quadratic hedging technique as well as the Black-Scholes hedging to observed option prices written on an equity index and calculate the empirical errors in the two cases. Our results indicate that smaller errors can be obtained with quadratic hedging in the models used than with hedging in the Black-Scholes framework.

    Paper V describes a model of an electricity market consisting of households that try to minimize their electricity cost by dynamic battery usage. We assume that the price process of electricity depends on the aggregated momentaneous electricity consumption. With this assumption, the cost minimization problem of each household is governed by a system of mean field game equations. We also provide an existence and uniqueness result for these mean field game equations. The equations are regularized and the approximate equations are solved numerically. We illustrate how the battery usage affects the electricity price.

  • Public defence: 2017-10-18 10:00 F3, stockholm
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Measures to Enhance the Dynamic Performance of Railway Catenaries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The pantograph-catenary system is used in railways to transfer electric power from infrastructure to trainset. As the pantograph slides against the catenary, the contact between the two surfaces is not stable due to stiffness variation, propagating wave and other environmental perturbation, especially at high speeds or in multi-pantograph operation. Heavy oscillation can result in poor power-transmission quality, electromagnetic interference, severe wear or even structural damage. So the pantograph-catenary dynamics has become one of the key issues which limits the operational speed and determines the maintenance cost. There are many types of catenary systems in Sweden, which are relatively soft and sensitive compared with the systems in other countries. They work well at low operational speed and have strict limitations to multi-pantograph operation. It is possible to achieve an operational speed of 350 km/h on newly-built high-speed lines, but there is still a large demand for higher operational speed and more capacity on the existing lines.

        Many researchers and engineers have made progress to improve its dynamic performance. From the research aspect, many numerical models have been built up to demonstrate the dynamics of the pantograph-catenary system and to unveil the key influencing factors. There have been many applications developed in recent years. Regarding the catenary, high-tensile loads on the catenary and low-stiffness-variation designs are widely used to improve the dynamic performance. Regarding the pantograph, aerodynamic-friendly designs and active-control technique contribute to the development of high-speed pantograph. But all these methods need not only large investment but long out-of-service. Considering the large scale and heavy service duty of the existing lines, it becomes almost impossible to completely upgrade the existing pantograph-catenary systems. So it is necessary to find practical and efficient methods to exploit the potentials of the existing systems to enhance their dynamic performances.

        This thesis investigates the dynamic behaviour of the Swedish pantograph-catenary systems and proposes methods for better usage. A numerical study on multi-pantograph operation is performed and the relationships between dynamic performance and some key parameters is established. By studying the multi-pantograph operation at short spacing distance, a method to use the leading pantograph as auxiliary pantograph is proposed to increase the operational speed on the soft catenary system. To ensure operational safety in abnormal conditions, numerical studies on pantograph raising/lowering processes and in catenary overlap sections are performed. By studying the influence of the lumped-mass on the dynamic performance, it shows that it is even possible to implement some artificial tuned-masses on the catenary for dynamic optimization.

  • Public defence: 2017-10-18 10:00 F3, Stockholm
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Measures to Enhance the Dynamic Performanceof Railway Catenaries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The pantograph-catenary system is used in railways to transfer electric power from infrastructure to trainset. As the pantograph slides against the catenary, the contact between the two surfaces is not stable due to stiffness variation, propagating wave and other environmental perturbation, especially at high speeds or in multi-pantograph operation. Heavy oscillation can result in poor power-transmission quality, electromagnetic interference, severe wear or even structural damage. So the pantograph-catenary dynamics has become one of the key issues which limits the operational speed and determines the maintenance cost. There are many types of catenary systems in Sweden, which are relatively soft and sensitive compared with the systems in other countries. They work well at low operational speed and have strict limitations to multi-pantograph operation. It is possible to achieve an operational speed of 350 km/h on newly-built high-speed lines, but there is still a large demand for higher operational speed and more capacity on the existing lines.Many researchers and engineers have made progress to improve its dynamic performance. From the research aspect, many numerical models have been built up to demonstrate the dynamics of the pantograph-catenary system and to unveil the key influencing factors. There have been many applications developed in recent years. Regarding the catenary, high-tensile loads on the catenary and low-stiffness-variation designs are widely used to improve the dynamic performance. Regarding the pantograph, aerodynamic-friendly designs and active-control technique contribute to the development of high-speed pantograph. But all these methods need not only large investment but long out-of-service. Considering the large scale and heavy service duty of the existing lines, it becomes almost impossible to completely upgrade the existing pantograph-catenary systems. So it is necessary to find practical and efficient methods to exploit the potentials of the existing systems to enhance their dynamic performances.This thesis investigates the dynamic behaviour of the Swedish pantograph-catenary systems and proposes methods for better usage. A numerical study on multi-pantograph operation is performed and the relationships between dynamic performance and some key parameters is established. By studying the multi-pantograph operation at short spacing distance, a method to use the leading pantograph as auxiliary pantograph is proposed to increase the operational speed on the soft catenary system. To ensure operational safety in abnormal conditions, numerical studies on pantograph raising/lowering processes and in catenary overlap sections are performed. By studying the influence of the lumped-mass on the dynamic performance, it shows that it is even possible to implement some artificial tuned-masses on the catenary for dynamic optimization.

  • Public defence: 2017-10-20 14:00 Kollegiesalen, Stockholm
    Nemati, Hamed
    KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS.
    Secure System Virtualization: End-to-End Verification of Memory Isolation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Over the last years, security-kernels have played a promising role in reshaping the landscape of platform security on embedded devices. Security-kernels, such as separation kernels, enable constructing high-assurance mixed-criticality execution platforms on a small TCB, which enforces isolation between components. The reduced TCB  minimizes the system attack surface and facilitates the use of formal methods to ensure the kernel functional correctness and security.

    In this thesis, we explore various aspects of building a provably secure separation kernel using virtualization technology. We show how the memory management subsystem can be virtualized to enforce isolation of system components. Virtualization is done using direct-paging that enables a guest software to manage its own memory configuration. We demonstrate the soundness of our approach by verifying that the high-level model of the system fulfills the desired security properties. Through refinement, we then propagate these properties (semi-)automatically to the machine-code of the virtualization mechanism.

    Further, we show how a runtime monitor can be securely deployed alongside a Linux guest on a hypervisor to prevent code injection attacks targeting Linux. The monitor takes advantage of the provided separation to protect itself and to retain a complete view of the guest.

    Separating components using a low-level software cannot by itself guarantee the system security. Indeed, current processors architecture involves features that can be utilized to violate the isolation of components. We present a new low-noise attack vector constructed by measuring caches effects which is capable of breaching isolation of components and invalidates the verification of a software that has been verified on a memory coherent model. To restore isolation, we provide several countermeasures and propose a methodology to repair the verification by including data-caches in the statement of the top-level security properties of the system.

    The full text will be freely available from 2017-09-29 16:06
  • Public defence: 2017-10-23 10:00 F3, Stockholm
    Walbrühl, Martin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    ICME guided development of cemented carbides with alternative binder systems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of alternative binder systems for tungsten carbide (WC) based cemented carbides has again become of relevance due to possible changes in EU regulations regarding the use of Cobalt (Co). A framework for the ICME (Integrated Computational Materials Engineering) based Materials Design is presented to accelerate the development of alternative binder systems.

    Part one of this work deals with the design of the cemented carbide composite hardness. It has been shown that the intrinsic binder hardness is comparable to a bulk metal alloy and that based on the binder solubilities a solid solution strengthening model developed in this work can be employed. Using a method presented in this work the non-equilibrium, frozen-in binder solubilities can be obtained. Both the design of the binder phase and composite hardness is presented based on a general Materials Design approach.

    Part two deals with a multiscale approach to model the surface gradient formation. The experimentally missing data on liquid binder diffusion has been calculated using AIMD (Ab initio Molecular Dynamics). The diffusion through the liquid cemented carbide binder has to be reduced to an effective diffusion value due to the solid carbides acting as obstacles that increase the diffusion path. The geometrical reduction of the diffusion has been investigated experimentally using the SIMS (secondary ion mass spectroscopy) technique in WC-Nickel-58Nickel diffusion couples. The geometrical contribution of the so-called labyrinth factor has been proven by the combination of the experiments and in conjunction with DICTRA simulations using the precise liquid AIMD diffusivities. Unfortunately, despite the improved kinetic database and the geometrical diffusion reduction, the surface gradient formation cannot be explained satisfactory in complex cemented carbide grades. Additional, but so far unidentified, contributions have to be considered to predict the surface gradient thickness.

  • Public defence: 2017-10-26 09:00 E3, Stockholm
    Granath Hansson, Anna
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Real Estate Planning and Land Law.
    Institutional prerequisites for affordable housing development: A comparative study of Germany and Sweden2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis was written against the background of intense public debate on increasing housing shortages and housing policy reform in Germany and Sweden. Potential reforms to increase housing development volumes, especially in the affordable segment, are analysed using theories of institutional change with focus on urban planning, building law and housing policy. The instruments analysed are divided into measures intended to increase housing supply elasticity and targeted affordable housing measures.

     

    Three measures intended to increase housing supply elasticity that could be transferable to Sweden are identified: 1) Development planning could be reformed through facilitated procedures, the introduction of private initiative in planning and new incentives of planning authorities. 2) The planning and building legislation could be reformed to facilitate building approvals in relation to serial housing construction, which in turn could increase the number of affordable homes being built. 3) City housing policy could promote housing development through more intense use of the policy instruments of organisation, urban planning, municipal land and subsidies, with city organisation and political attention to housing markets being identified as crucial.

     

    However, effectively targeted affordable housing policies are difficult to implement under the current Swedish housing policy regime. In the short term, Swedish housing policy should therefore concentrate on housing supply elasticity-enhancing measures. However, considering the increasing pressure on the affordable housing supply and future expected demographic changes, public discussion of potential future solutions would be valuable. A first step would be to compile housing statistics such that the affordable housing shortage and the opportunities to design effective measures to counter it could be better understood.

  • Public defence: 2017-10-26 10:00 Sal F3, Stockholm
    Lindvall, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling. Swerea MEFOS.
    A Study on Vanadium Extraction from Fe-V-P Melts Derived from Primary and Secondary Sources2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Vanadium extraction methods were developed for iron-vanadium-phosphorus (Fe-V-P) melts derived from processing of V-bearing titanomagnetites and steel slags. Studies on phase relationships of V slags were carried out to provide important understanding of the extraction processes. Phase relationship in vanadiferous slag was investigated experimentally at 1573K, 1673K and 1773K, for the compositional range of 0-6mass% Al2O3, 1-5mass% CaO, 10-17mass% SiO2, with MnO and V2O3 fixed at 5.5mass% and 30mass%, balanced with FeO. The slags were found to be solid-liquid mixtures, of liquid, spinel and in some cases free silica. Alumina was identified as the preferred additive to prohibit precipitation of free silica. A method for V extraction to vanadiferous slag was developed based on Fe-V(2mass%)-P(0.1mass%) melts at 1677K using a semi-industrial scale BOF. Oxidation was carried out with an oxygen enriched air jet and iron ore pellets. The complete dissolution of pellets was achieved by deliberately creating good stirring conditions utilising high momentary decarburisation rates. The P distribution to the slag was low when good stirring conditions was obtained. Phase relationship in Al2O3-CaO(25-35mass%)-SiO2-VOx slag was investigated experimentally at an oxygen partial pressure of 9.37•10-11atm and 1873K. The maximum solubility of V-oxide in the slag was 9-10mass% V2O3. Two solid phases were found, a solid solution of Al2O3 in V2O3 (karelianite) and hibonite with fractionation of V into the crystal structure. V extraction experiments to Al2O3-CaO-SiO2 based slags were carried out in 150kg scale by blowing CO2 gas into the metal bath consisting mainly of 1-10mass% V and 1mass% P. At these conditions, oxidation of V was favoured over Fe. Up to 10-13mass% V2O3 could be dissolved in the slag before a viscous slag saturated in V-oxide was observed. The phosphate capacity in the slag was low and as a result this slag could at once be subjected to a final reduction step for production of ferrovanadium with 40-50mass% V.

  • Public defence: 2017-10-27 10:00 Sal F3, Stockholm
    Wang, Huijun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    A Study on the Reaction between MgO Based Refractories and Slag-Towards the Development of Carbon-free Lining Material2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In present thesis, the fundamental studies on the reaction between MgO based refractories and slag were undertaken for the development of a carbon-free bonding MgO lining material. Alumina was selected as a potential binder material. Due to MgO-Al2O3 chemical reaction, the developed refractory was bonded by MgO·Al2O3 spinel phase. To begin with, an investigation of the dissolution process of dense MgO and MgO·Al2O3 spinel in liquid slag was carried out. To obtain reliable information for dissolution study, a new experimental method was therefore developed. In this method, a cylinder was rotating centrally in a special designed container with a quatrefoil profile. This method also showed a good reliability in revealing the dissolution mechanism by quenching the whole reaction system. The experimental results showed that the dissolution process of MgO and spinel was controlled by both mass transfer and chemical reaction. It was found that the rapid dissolution of spinel was mainly because of its larger driving force. To improve the resistance against slag penetration, two aspects were studied to develop carbon-free MgO refractory. First, colloidal alumina was used and the effect of its addition into MgO matrix was investigated. The use of colloidal alumina was to form bonding products in the grain boundary of MgO. The results showed that the alumina addition greatly improved the resistance of MgO based refractory against slag penetration in comparison with the decarburized MgO-carbon refractory. It was found that the improvement of resistance was mainly related to the spinel-slag reaction products of CaO·Al2O3 and CaO·MgO·Al2O3 solid phases at the grain boundaries. Second, the effect of particle size distribution on the penetration resistance of MgO was investigated. The most profound improvement against the slag penetration was obtained by using a proper particle size distribution. The results highlighted the importance of considering the refractory structure. Experiments were undertaken to investigate the dissolution mechanism of different types of MgO based refractories in liquid slag. It was observed that the dissolution of spinel bonded MgO refractory was much slower than the decarburized MgO-carbon refractory. The primary dissolution in spinel bonded MgO refractory occurred at the slag-penetrated layer, and the removal of this layer by peeling off enhanced the dissolution rate rapidly.

  • Public defence: 2017-10-27 10:00 Senaatszaal, Delft
    Koirala, Binod Prasad
    KTH, School of Electrical Engineering (EES).
    Integrated Community Energy Systems2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Energy systems across the globe are going through a radical transformation as a result of technological and institutional changes, depletion of fossil fuel resources, and climate change. Accordingly, local energy initiatives are emerging and increasing number of the business models are focusing on the end-users. This requires the present centralized energy systems to be re-organized. In this context, Integrated community energy systems (ICESs) are emerging as a modern development to re-organize local energy systems allowing simultaneous integration of distributed energy resources (DERs) and engagement of local communities. With the emergence of ICESs new roles and responsibilities as well as interactions and dynamics are expected in the energy system. Although local energy initiatives such as ICESs are rapidly emerging due to community objectives, such as cost and emission reductions as well as resiliency, assessment and evaluation of the value that these systems can provide to both local communities and the whole energy system are still lacking. The value of ICESs is also impacted by the institutional settings internal and external to the system. With this background, this thesis aims to understand the ways in which ICESs can contribute to enhancing the energy transition.

    This thesis utilizes a conceptual framework consisting of institutional and societal levels in order to understand the interaction and dynamics of ICESs implementation.  Current energy trends and the associated technological, socio-economic, environmental and institutional issues are reviewed. The developed ICES model performs optimal planning and operation of ICESs and assesses their performance based on economic and environmental metrics. For the considered community size and local conditions, grid-connected ICESs are already beneficial to the alternative of solely being supplied from the grid, both in terms of total energy costs and CO2 emissions, whereas grid-defected systems, although performing very well in terms of CO2 emissions reduction, are still rather expensive. ICESs ensure self-provision of energy and can provide essential system services to the larger energy system. This thesis has demonstrated the added value of ICESs to the individual households, local communities and the society. A comprehensive institutional design considering techno-economic and institutional perspectives is necessary to ensure effective contribution of ICESs in the energy transition.

    The full text will be freely available from 2017-10-27 12:35
  • Public defence: 2017-11-17 13:00 F3, Stockholm
    Vass, Susanna
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Project Communication.
    The Business Value of BIM: Elaborating on Content and Perspective2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The expectations on digitalization and Building Information Modeling (BIM) in the Architectural, Engineering and Construction (AEC) are high. The high expectations are reflected in an increasing interest for the term business value of BIM. However, the practical and theoretical understanding of its content and perspective is characterized by rationalism and positivism commercially promoted by industry. This thesis aims to reflect on, problematize and extend the theoretical understanding of the content and perspective of the business value of BIM. Perceptions about business value of BIM, the associated challenges and costs and the role of the business of BIM in a wider socio-technical context are examined among Swedish and international AEC industry actors and a large Swedish public infrastructure client. To extend the understanding of the content and perspective of the business value of BIM, the rational and process-oriented theories on the business value of IT are combined with the more interpretive and hermeneutic socio-technical systems theory. A social and cognitive dimension is thus added to the understanding of the business value of BIM and business value of IT.  By combining the two research fields and contributing with the socio-technical perspective to the theoretical understanding of business value, this thesis contributes with theory development of the understanding of business value BIM and business value of IT.  For practitioners, the thesis shows the complex, multi-dimensional and challenging aspects of implementing BIM for business value. The journey of perspectives in this thesis from positivism towards increased interpretivism also sheds light on the implications of when different perspectives exert influence on a research field (hegemony) and wishes to provide a contrast and balance to the rational and positivistic perspectives in BIM research. It also wishes to inspire future BIM research to broaden the theoretical perspectives.