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  • Public defence: 2018-02-28 10:00 FA32, Stockholm
    Fahleson, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Derivation and application of response functions for nonlinear absorption and dichroisms2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is titled ’Derivation and application of response functions for nonlinear absorption and dichroisms’ and was written by Tobias Fahleson at the Division of Theoretical Chemistry & Biology at KTH Royal Institute of Technology in Sweden. It explores and expands upon theoretical means of quantifying a number of nonlinear spectroscopies, including two-photon absorption, resonant inelastic x-ray scattering, Jones birefringence, and magnetic circular dichroism. Details are provided for the derivation and program implementation of complex-valued (damped) cubic response functions that have been implemented in the quantum chemistry package DALTON [1], based on working equations formulated for an approximate-state wave function. This is followed by an assessment of the implementation. It is demonstrated how two-photon absorption (TPA) can be described either through second-order transition moments or the damped cubic response function. A set of illustrative TPA profiles are produced for smaller molecules. In addition, resonant inelastic x-ray scattering (RIXS) is explored in a similar manner as two-photon absorption. It is shown for small systems how RIXS spectra may be obtained using a reduced form of the cubic response function. Linear birefringences are investigated for noble gases, monosubstituted benzenes, furan homologues, and liquid acetonitrile. Regarding the noble gases, the Jones effect is shown to be proportional to a power series with respect to atomic radial sizes. For monosubstituted benzenes, a linear relation between the Jones birefringence and the empirical para-Hammett constant as well as the permanent electric dipole moment is presented. QM/MM protocols are applied for a pure acetonitrile liquid, including polarizable embedding and polarizable-density embedding models. The final chapter investigates magnetically induced circular dichroism (MCD). A question regarding relative stability of the first set of excited states for DNA-related molecular systems is resolved through MCD by exploiting the signed nature of circular dichroisms. Furthermore, to what extent solvent contributions affect MCD spectra and the effect on uracil MCD spectrum due to thionation is studied.

  • Public defence: 2018-03-02 10:00 Kollegiesalen, Stockholm
    Schröder, Stephan
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems. SenseAir AB.
    Towards Unconventional Applications of Wire Bonding2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents novel heterogeneous integration approaches of wire materials to fabricated and package MEMS devices by exploring unconventional applications of wire bonding technology. Wire bonding, traditionally endemic in the realm of device packaging to establish electrical die-to-package interconnections, is an attractive back-end technology, offering promising features, such as high throughput, flexibility and placement accuracy. Exploiting the advantages of state-of-the-art wire bonding technology and substitute the conventional micro welding approach with an innovative attachment concept, a generic integration platform for a multitude of wire materials is provided. This facilitates a cost-efficient and selective integration, which involves the attachment and shaping of a variety of intrinsically non-bondable wire materials. Furthermore, the selective integration of wire materials provides a simple method to generate complex suspended geometries, which circumvents the need for subsequent processing. The first part of this thesis reports of the integration of non-bondable shape memory alloy wires on wafer-level, which has led to an innovative method to fabricate micro actuators. Moreover, the integration of high performance resistive heating wires on chip-level is utilized to fabricate filament based infrared emitters, targeting non-dispersive infrared gas sensing of alcohol for automotive applications. In the second part, a series of unconventional applications of wire integration using the traditional thermo-sonic wire bonding approach is presented. A novel and low-cost nitric oxide gas sensor is realized by producing vertical bond wires featuring high aspect ratio. Next, the high placement accuracy of wire bonding tools is leveraged to integrate conductive metals cores for fabricating high aspect ratio through silicon vias. Finally, an advanced packaging approach for stress-sensitive MEMS gyroscopes is evaluated, which exclusively utilizes bond wires for realizing the die attachment.

  • Public defence: 2018-03-02 14:00 F3, Stockholm
    Nair, Anu G.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Modeling Biochemical Network Involved in Striatal Dopamine Signaling2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis, I studied the molecular integration of reward-learning related neuromodulatory inputs by striatal medium-sized projection neurons (MSNs) using mass-action kinetic modeling.

    It is known that, in reward learning, an unexpected reward results in transient elevation in dopamine (peak) whereas omission of an expected reward leads to transient dopamine decrease (dip). In silico experiments performed in the current study indicated that reward-related transient dopamine signals could act differentially on the cAMP/PKA signaling of the two MSN classes, D1 receptor expressing MSNs (D1 MSNs) and D2 receptor expressing MSNs (D2 MSNs). PKA in D1 MSN responded to dopamine peaks, whereas in D2 MSN it was affected by dopamine dips. Simulations further highlighted the possibility that cAMP/PKA signaling in D1 MSNs is tonically inhibited by acetylcholine by activating muscarinic M4 receptors under the basal condition. In this scenario, the D1 receptor activation by a dopamine peak does not have any downstream effect, unless the dopamine peak is accompanied by an acetylcholine dip that could release the M4-mediated inhibition. Such acetylcholine dips accompany dopamine peaks due to the time-locked dopaminergic bursts and cholinergic pauses observed in reward-learning. Thus, an acetylcholine dip could be viewed as a time window for dopamine signaling in D1 MSN. Similarly, the cAMP/PKA signaling in D2 MSN could be tonically inhibited by the dopamine-dependent D2 receptors. In this case, a dopamine dip results in the cAMP/PKA activation, and the strength of the downstream response depends on the level of basal adenosine, acting via A2a receptors. These results highlight how multiple neuromodulators could be integrated by striatal MSNs to produce effective downstream response. Such signal integration scenarios require that the dopamine and acetylcholine-triggered cAMP signaling be sufficiently powerful and sensitive. However, quantitative information regarding the efficacy of dopamine and acetylcholine on cAMP signaling is virtually nonexistent for living MSNs. Therefore, the effects of dopamine and acetylcholine on cAMP signaling were quantitatively characterized in this study by imaging genetically-encoded FRET-based biosensor expressed in mice brain slices. The measurements confirmed that the cAMP signaling in MSNs is quite sensitive and could strongly be influenced by neuromodulators, thus supporting the underlying model requirements, and thereby predictions.

    Another parameter that is important for effective molecular signal integration is the relative timing between various convergent inputs. For example, studies have shown that LTP in D1 MSNs is produced if corticostriatal glutamate synaptic activity is shortly followed by a dopamine peak. However, there is no LTP if the order of the inputs is reversed. This temporal dependence is believed to result in various aspects of reward learning, such as reward causality, and is theoretically represented by the so-called eligibility trace. However, little is known how such temporal constraints emerge at the level of molecular signaling. I investigated the possible molecular mechanism responsible for the emergence of this temporal constraints, using computational modeling. This study proposes a novel molecular mechanism based on the coordinated activity of two striatally enriched phosphoproteins, DARPP-32 and ARPP-21 that could explain the emergence of the timing-dependence for postsynaptic signal integration, and thus a plausible molecular underpinning for the eligibility trace of reward learning.

    In summary, the results presented in this thesis advance our understanding on how the striatal cAMP respond towards reward-related nueromodulator signals, and the downstream effects on synaptic signaling and reward learning.

  • Public defence: 2018-03-05 13:15 F3, Stockholm
    Belic, Jovana
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Untangling Cortico-Striatal Circuitry and its Role in Health and Disease - A computational investigation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The basal ganglia (BG) play a critical role in a variety of regular motor and cognitive functions. Many brain diseases, such as Parkinson’s diseases, Huntington’s disease and dyskinesia, are directly related to malfunctions of the BG nuclei. One of those nuclei, the input nucleus called the striatum, is heavily connected to the cortex and receives afferents from nearly all cortical areas. The striatum is a recurrent inhibitory network that contains several distinct cell types. About 95% of neurons in the striatum are medium spiny neurons (MSNs) that form the only output from the striatum. Two of the most examined sources of GABAergic inhibition into MSNs are the feedback inhibition (FB) from the axon collaterals of the MSNs themselves, and the feedforward inhibition (FF) via the small population (1-2% of striatal neurons) of fast spiking interneurons (FSIs). The cortex sends direct projections to the striatum, while the striatum can affect the cortex only indirectly through other BG nuclei and the thalamus. Understanding how different components of the striatal network interact with each other and influence the striatal response to cortical inputs has crucial importance for clarifying the overall functions and dysfunctions of the BG.

        In this thesis I have employed advanced experimental data analysis techniques as well as computational modelling, to study the complex nature of cortico-striatal interactions. I found that for pathological states, such as Parkinson’s disease and L-DOPA-induced dyskinesia, effective connectivity is bidirectional with an accent on the striatal influence on the cortex. Interestingly, in the case of L-DOPA-induced dyskinesia, there was a high increase in effective connectivity at ~80 Hz and the results also showed a large relative decrease in the modulation of the local field potential amplitude (recorded in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats) at ~80 Hz by the phase of low frequency oscillations. These results suggest a lack of coupling between the low frequency activity of a presumably larger neuronal population and the synchronized activity of a presumably smaller group of neurons active at 80 Hz.

        Next, I used a spiking neuron network model of the striatum to isolate the mechanisms underlying the transmission of cortical oscillations to the MSN population. I showed that FSIs play a crucial role in efficient propagation of cortical oscillations to the MSNs that did not receive direct cortical oscillations. Further, I have identified multiple factors such as the number of activated neurons, ongoing activity, connectivity, and synchronicity of inputs that influenced the transfer of oscillations by modifying the levels of FB and FF inhibitions. Overall, these findings reveal a new role of FSIs in modulating the transfer of information from the cortex to striatum. By modulating the activity and properties of the FSIs, striatal oscillations can be controlled very efficiently. Finally, I explored the interactions in the striatal network with different oscillation frequencies and showed that the features of those oscillations, such as amplitude and frequency fluctuations, can be influenced by a change in the input intensities into MSNs and FSIs and that these fluctuations are also highly dependent on the selected frequencies in addition to the phase offset between different cortical inputs.

        Lastly, I investigated how the striatum responds to cortical neuronal avalanches. Recordings in the striatum revealed that striatal activity was also characterized by spatiotemporal clusters that followed a power law distribution albeit, with significantly steeper slope. In this study, an abstract computational model was developed to elucidate the influence of intrastriatal inhibition and cortico-striatal interplay as important factors to understand the experimental findings. I showed that one particularly high activation threshold of striatal nodes can reproduce a power law-like distribution with a coefficient similar to the one found experimentally. By changing the ratio of excitation and inhibition in the cortical model, I saw that increased activity in the cortex strongly influenced striatal dynamics, which was reflected in a less negative slope of cluster size distributions in the striatum.  Finally, when inhibition was added to the model, cluster size distributions had a prominently earlier deviation from the power law distribution compared to the case when inhibition was not present. 

  • Public defence: 2018-03-07 10:00 F3, Stockholm
    Fu, Qiliang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Wood Nanotechnologies for Transparency, Fire Retardancy and Liquid Separation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

  • Public defence: 2018-03-09 09:00 sal C, STOCKHOLM
    Soliman, Amira
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    Graph-based Analytics for Decentralized Online Social Networks2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Decentralized Online Social Networks (DOSNs) have been introduced as a privacy preserving alternative to the existing online social networks.  DOSNs remove the dependency on a centralized provider and operate as distributed information management platforms. Current efforts of providing DOSNs are mainly focused on designing the required building blocks for managing the distributed network and supporting the social services (e.g., search, content delivery, etc.). However, there is a lack of reliable techniques for enabling complex analytical services (e.g., spam detection, identity validation, etc.) that comply with the decentralization requirements of DOSNs. In particular, there is a need for decentralized data analytic techniques and machine learning (ML) algorithms that can successfully run on top of DOSNs.

     

    In this thesis, we empower decentralized analytics for DOSNs through a set of novel algorithms. Our algorithms allow decentralized analytics to effectively work on top of fully decentralized topology, when the data is fully distributed and nodes have access to their local knowledge only. Furthermore, our algorithms and methods are able to extract and exploit the latent patterns in the social user interaction networks and effectively combine them with the shared content, yielding significant improvements for the complex analytic tasks. We argue that, community identification is at the core of the learning and analytical services provided for DOSNs. We show in this thesis that knowledge on community structures and information dissemination patterns, embedded in the topology of social networks has a potential to greatly enhance data analytic insights and improve results. At the heart of this thesis lies a community detection technique that successfully extracts communities in a completely decentralized manner. In particular, we show that multiple complex analytic tasks, like spam detection and identity validation,  can be successfully tackled by harvesting the information from the social network structure. This is achieved by using decentralized community detection algorithm which acts as the main building block for the community-aware learning paradigm that we lay out in this thesis. To the best of our knowledge, this thesis represents the first attempt to bring complex analytical services, which require decentralized iterative computation over distributed data, to the domain of DOSNs. The experimental evaluation of our proposed algorithms using real-world datasets confirms the ability of our solutions to generate  efficient ML models in massively parallel and highly scalable manner.

  • Public defence: 2018-03-09 10:00 Kollegiesalen, Stockholm
    Moradi Nour, Zeinab
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Numerical study of dynamics of mass-emitting particles in multi-phase flow2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Suspended particles can be found in wide range of industrial applications such as food industry, mining industry and energy conversion processes. Depending on flow cases which particles are involved, different dynamics and motions are expected from suspended particles. In addition, it is well-known that existence of particles alters the configuration of surrounding flow.

    Fuel particles are expected to be found to gasify or evaporate in energy conversion processes . Burning (or combustion) of a fuel particle results in the production of a thin film of gas on the surface of the particle. The flow around the particle and existence of the thin film due to the combustion, might be the source of changes in particle-particle interaction, particle interaction with the surrounding fluid and walls. In order to investigate these phenomena, we apply a radial outflow boundary condition on the surface of particles to resemble gasification/evaporation of solid particles or droplet fuels.

    To study the effect of outflow from the surface of particles, we consider two generic cases; particles in shear flow and sedimentation of particles. These cases have been studied thoroughly in literature in which both behavior of the particle and pattern of the surrounding flow has been investigated. This provides us an opportunity to analyze our results against these well studied cases. In agreement with previous studies, it is observed that the radial outflow results to a decrease in drag and lift forces and an increase in pressure on the surface of the particle. Thence, a growth in maximum velocity of settling spherical particle and a decay in angular velocity of rotating particle by increasing outflow rate can be observed. Furthermore, a general hindering effect in particles interaction is detected. Considering the configuration of the background flow, different flow streamlines lead to different particle trajectories in a simple shear flow, in existence of outflow from the surface of particles.

    In the last part of the thesis we consider 3D simulations of three-phase flow (gas-liquid-particle) in which particle and bubble are moving under external forces and interacting with each other. In this case, we apply a non-wetting boundary condition on the surface of solid particle. A compound consist of a particle entrapped inside a bubble, preforms different behaviors depending on the competition between gravitational and surface tension induced forces.

    Regarding the numerical method, we apply a lattice Boltzmann method (LBM) together with momentum exchange approach in order to couple particle and fluid. However, to capture phase interfaces in simulation of three-phase flows, a pseudo-potential method is considered . 

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

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

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

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

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

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

  • Public defence: 2018-03-14 14:47 F3, Stockholm
    Hajian, Alireza
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Institute of Technology.
    Cellulose–Assisted Dispersion of Carbon Nanotubes: From Colloids to Composites2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is a challenge to disperse nanoparticles to obtain a nanostructured composite. This thesis aims at providing a new route to fabricate carbon nanotube (CNT) composites and suggests mechanisms for nanocellulose–CNT interactions. This route is based on unmodified CNT dispersed in water with the help of nanocellulose. Chemical functionalization of the CNTs and the addition of surfactants are avoided. Thus, the mechanical and electrical properties of such nanotube composites can be improved.

    Cellulose derivatives can disperse and stabilize carbon nanotubes in water. Nanocellulose particles, such as cellulose nanofibrils (CNF), are a new form of cellulose derivatives that are able to disperse and stabilize untreated carbon nanotubes in water. The utilization of the hybrid CNF–CNT dispersions are shown to lead to strong nanostructured composites with high nanotube content and conductivity. The mechanism behind the dispersive action of nanocellulose for nanotubes is explored and studied in detail. The dispersive ability of the nanocellulose leads to improved properties of CNF–CNT composites.

    Apart from studies of structure and properties of composite fibers and films, two different functional materials are studied in detail. One is to form conductive patterns on cellulose nanopaper for the stable function of printed electronics in various environmental conditions and during handling. The second is to use a water-soluble cellulosic polymer–nanotube dispersion to fabricate superelastic aerogels without any chemical crosslinking or the addition of another component. This makes the aerogels easily recyclable (redispersible in water) and opens a new route for recyclable superelastic CNT composite aerogels.

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

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

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

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

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

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

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

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

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

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

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

  • Public defence: 2018-03-23 11:00 Madrid
    Mazidi, Peyman
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems. Comillas Pontifical University.
    From Condition Monitoring to Maintenance Management in Electric Power System Generation with focus on Wind Turbines2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    With increase in the number of sensors installed on sub-assemblies of industrial components, the amount of data collected is rapidly increasing. These data hold information in the areas of operation of the system and evolution of health condition of the components. Therefore, extracting the knowledge from the data can bring about significant improvements in the aforementioned areas.

    This dissertation provides a path for achieving such an objective. It starts by analyzing the data at the sub-assembly level of the components and creates four frameworks for analysis of operation and maintenance (O&M) for past, present and future horizons at the component level. These frameworks allow improvement in operation, maintenance planning, cost reduction, efficiency and performance of the industrial components. Next, the dissertation evaluates whether such models can be linked with system level analysis and how providing such a link could provide additional improvements for system operators. Finally, preventive maintenance (PM) in generation maintenance scheduling (GMS) in electric power systems is reviewed and updated with recent advancements such as connection to the electricity market and detailed implementation of health condition indicators into the maintenance models. In particular, maintenance scheduling through game theory in deregulated power system, for offshore wind farm (OWF) and an islanded microgrid (MG) are investigated.

    The results demonstrate improvements in reducing cost and increasing profit for the market agents and system operators as well as asset owners. Moreover, the models also deliver an insight on how direct integration of the collected operation data through the developed component level models can assist in improving the operation and management of maintenance for the system.