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  • Anton, Nicholas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Engine Optimized Turbine Design2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The focus on our environment has never been as great as it is today. The impact of global warming and emissions from combustion processes become increasingly more evident with growing concerns among the world’s inhabitants. The consequences of extreme weather events, rising sea levels, urban air quality, etc. create a desperate need for immediate action. A major contributor to the cause of these effects is the transportation sector, a sector that relies heavily on the internal combustion engine and fossil fuels. The heavy-duty segment of the transportation sector is a major consumer of oil and is responsible for a large proportion of emissions.

    The global community has agreed on multiple levels to reduce the effect of man-made emissions into the atmosphere. Legislation for future reductions and, ultimately, a totally fossil-free society is on the agenda for many industrialized countries and an increasing number of emerging economies.

    Improvements of the internal combustion engine will be of importance in order to effectively reduce emissions from the transportation sector both presently and in the future. The primary focus of these improvements is undoubtedly in the field of engine efficiency. The gas exchange system is of major importance in this respect. The inlet and exhaust flows as the cylinder is emptied and filled will significantly influence the pumping work of the engine. At the center of the gas exchange system is the turbocharger. The turbine stage of the turbocharger can utilize the energy in the exhaust flow by expanding the exhaust gases in order to power the compressor stage of the turbocharger.

    If turbocharger components can operate at high efficiency, it is possible to achieve high engine efficiency and low fuel consumption. Low exhaust pressure during the exhaust stroke combined with high pressure at the induction stroke results in favorable pumping work. For the process to work, a systems-based approach is required as the turbocharger is only one component of the engine and gas exchange system.

    In this thesis, the implications of turbocharger turbine stage design with regards to exhaust energy utilization have been extensively studied. Emphasis has been placed on the turbine stage in a systems context with regards to engine performance and the influence of exhaust system components.

    The most commonly used turbine stage in turbochargers, the radial turbine, is associated with inherent limitations in the context of exhaust energy utilization. Primarily, turbine stage design constraints result in low efficiency in the pulsating exhaust flow, which impairs the gas exchange process. Gas stand and numerical evaluation of the common twin scroll radial turbine stage highlighted low efficiency levels at high loadings. For a pulse-turbocharged engine with low exhaust manifold volume, the majority of extracted work by the turbine will occur at high loadings, far from the optimum efficiency point for radial turbines. In order for the relevant conditions to be assessed with regards to turbine operation, the entire exhaust pulse must be considered in detail. Averaged conditions will not capture the variability in energy content of the exhaust pulse important for exhaust energy utilization.

    Modification of the radial turbine stage design in order to improve performance is very difficult to achieve. Typical re-sizing with modifying tip diameter and trim are not adequate for altering turbine operation into high efficiency regions at the energetic exhaust pulse peak.

    The axial turbine type is an alternative as a turbocharger turbine stage for a pulse-turbocharged engine. The axial turbine stage design can allow for high utilization of exhaust energy with minimal pressure interference in the gas exchange process; a combination which has been shown to result in engine efficiency improvements compared to state-of-the-art radial turbine stages.

    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product and Service Design.
    Verifiering av accelerometer mätning i 16-bitars mikrokontroller2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report is a final thesis report at the institution of Mechatronics at KTH (The Royal institute of Technology). In this report two methods for development and verification are compared for acceleration analysis in a weapon with a microcontroller (hence called µC). A µC of type MSP430G2553 is used as target system. The goal of the µC's program is to determine if an acceleration pattern is a recoil or not. In the report two methods are presented for verification and development. Alternative 1 is limited to using the target µC and software tools associated with it. Alternative 2 is using the target µC and software tools but also and additional combination instrument which includes both oscilloscope and arbitrary waveform generator. The combination instrument was used to measure several recoil acceleration patterns. These reference measurements were used to simulate accelerometer for the target system. The conclusion is that alternative 2's use of the combination instrument is of great benefit in several perspectives. Alternative 1's also has several benefits. Furthermore alternative 2 enables early identification of the acceleration data without the limits of the µC as memory constraints and program defects. The combination instrument is a useful tool for development, as it can be used as a small HIL-system

  • Public defence: 2019-05-22 10:00 643, Stockholm
    Darwish, Rami
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    The Missing link: Business Models Lock-in in Sociotechnical Transitions2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Societal and environmental challenges present challenges for our current industrial systems. In order to respond to these difficulties, various alternative systems have been suggested, as they promise sustainability and increased societal quality of life enabled by innovative technologies. These future solutions hold the capacity to solve problems by unlocking considerable business potential. However, the journey to the forthcoming era will bring dramatic changes, not only to the success of incumbent industrial stakeholders but also to their very existence. The upcoming changes are impregnated with hazards to current business models of successful organizations. So, one may ask what impact future technologies may have on the realms that industrial actors live in? To disentangle the complexity of the unknowns, multitudes of collaborative efforts in protected spaces have emerged globally to experiment with potential systems on the road to sociotechnical transitions.

    The transport sector is undergoing efforts towards transitions to future sustainable systems. This sector has a special focus when it comes to sustainability challenges due to its substantial economic and environmental impact.  Bus systems are at the heart of this challenge due to the central role they play in urban mobility. Hence, different fuels and charging technologies for buses have been tested in pilot projects to facilitate the march towards sustainability; electric charging is one of the promising technologies, which achieve this aim. However, current business models of incumbent transport stakeholders seem to be problematic, and changes to facilitate the transitions seem to be complex.

    Extant literature indicates a critical role of business models under sociotechnical transitions. Theoretically, there is an underlying need for incumbents to change their business models to reap the benefits of innovative technologies. However, this change is difficult and potential business models are far from clear. With that, the dynamics of business models under transition remains as an underexplored area, and the challenge to incumbent business models poses itself as an interesting area to gauge. Under this umbrella, a question arises regarding how the pressure on incumbent business models interacts with systemic innovations.

    This thesis is a case study of an incumbent bus operator participating in a pilot project on a future bus system. The case study is in-depth in nature and investigates the potential business model of a bus operator in a multiple stakeholder pilot project, which tests an inductive electric hybrid bus. With a strong empirical exploratory nature, this thesis is built on an “insider” single case study that occurred in the year 2016-2017. The focus of the study is on the pressure on bus operator business model in the face of systemic innovation. The findings reveal positive future value proposition, disrupted value creation, and unclear value capture in the potential business model of the operator. Moreover, the findings show lock-in and resource dependence situation of the operator’s current business model. The lock-in of the business model hinder the transition to future sociotechnical bus system and makes it difficult to commercialize the new technology.

    The outcome of this thesis speaks to a significant influence of history and the regulator, manifested by rules on the future of business models of commercial incumbent stakeholders. This demonstrates lock-in may prove to be a major impediment, and that unchained and flexible business model of incumbents is critical for further continuation of successful shifts. Given these findings, this thesis suggests applying the business model lens to pilot projects for sustainability. This would aid in better comprehending how current business models may facilitate or hinder favorable transitions. This knowledge informs both managerial decisions and policy making, especially when it comes to resource optimization and investment decisions.

  • Public defence: 2019-06-13 09:30 Sal B, Kista
    Farshin, Alireza
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Realizing Low-Latency Internet Services via Low-Level Optimization of NFV Service Chains: Every nanosecond counts!2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    By virtue of the recent technological developments in cloud computing, more applications are deployed in a cloud. Among these modern cloud-based applications, some require bounded and predictable low-latency responses. However, the current cloud infrastructure is unsuitable as it cannot satisfy these requirements, due to many limitations in both hardware and software.

    This licentiate thesis describes attempts to reduce the latency of Internet services by carefully studying the currently available infrastructure, optimizing it, and improving its performance. The focus is to optimize the performance of network functions deployed on commodity hardware, known as network function virtualization (NFV). The performance of NFV is one of the major sources of latency for Internet services.

    The first contribution is related to optimizing the software. This project began by investigating the possibility of superoptimizing virtualized network functions(VNFs). This began with a literature review of available superoptimization techniques, then one of the state-of-the-art superoptimization tools was selected to analyze the crucial metrics affecting application performance. The result of our analysis demonstrated that having better cache metrics could potentially improve the performance of all applications.

    The second contribution of this thesis employs the results of the first part by taking a step toward optimizing cache performance of time-critical NFV service chains. By doing so, we reduced the tail latencies of such systems running at 100Gbps. This is an important achievement as it increases the probability of realizing bounded and predictable latency for Internet services.

  • Lindberg, Boel
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Resilience in urban hydrology: A study of storm water management in the municipality of Stockholm2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The environmental issues of storm water in the urban environment is addressed in political policies on many different governance levels. The concept of “sustainable storm water” in Europe uses the natural water cycle as a template for urban drainage, and the EU has a water framework directive (WFD) with a systems approach, using drainage basins as the starting point of all actions. In Stockholm, a new storm water strategy was adopted in 2015 with a sustainability approach, using much of the terminology from the WFD and the Swedish Water & Wastewater Association. To find new aspects related to sustainable development of storm water management in Stockholm, this study used a resilience framework of seven principles to analyse the implementation of the Stockholm storm water strategy (SSWS). A mixed method approach was used for a qualitative study, using interviews and a review of policy documentation as the main data sources, complemented by a desk study of literature on the subject of storm water management, as well as participation in some relevant workshops. To broaden the study, examples from a developing area within the Stockholm municipality, Stora Sköndal, was used, as well as another municipality in the Baltic Sea region; Helsinki (Finland). The SSWS leans on the legislation of the environmental quality standards (EQS) but is lacking in authority coordination on a national and municipal level in Stockholm. Diversity in problem formulations and solutions for infrastructure is high, so is the diversity of involved stakeholders, which is an indication of resilience. This in combination with the structure and communicational links having questionable functionality, leads to a complex and inefficient structure in management of storm water, which undermines the resilience of the system. However, since the SSWS and other connected policies (such as local programmes of measures and sustainability requirements) are new, the system is undergoing change, which shows some level of adaptability and complex adaptive systems (CAS) thinking, another resilience indicator. The implementation of the WFD on a municipal level is also connected to CAS thinking, as well as a polycentric governance system -one of the seven resilience principles of the framework used. Some of the main issues found within this study for building resilience in the SES are related to follow-up and responsibility division.

  • Public defence: 2019-05-10 15:00 D3, Stockholm
    Dastory, Linda
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Economics.
    Innovation, Technical Change and the Labour Market2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This doctoral thesis consist of four papers. The two first papers are related to financialeconomics and the other two to labour economics. All four papers deal with microeconomicsanalysis of individuals and firms. Where the first two are from a firms perspectiveand the two second once are from an individual perspective. Moreover, all four papersunderline the importance of innovation for productivity,competitiveness and economicgrowth.In the first essay we use German Community Innovation Survey to identify financiallyconstrained firms. Contrary to previous studies we find that the relationship betweenfinancial constraints and firm size is inverted u-shaped and that it is the group ofmedium sized firms which has the largest funding gaps. This is explained by the factthat these firms have high innovation capabilities but at the same time face high cost ofcapital. Furthermore, we test if financial constraints have an impact on firm productivitygrowth. We find negative effects from funding gaps on productivity, but only for investmentin tangible capital and not for innovation investments.The second essay investigates whether there has been a change in the productivityand funding mix of innovative SMEs post stricter bank regulations. Our result showsthat the likelihood of using bank loans as a funding source has not changed for innovationinvestments nor for tangible investments after stricter capital regulations have beenannounced. On the other hand, sources such as subsidies have increased due to regulatoryprograms that have been implemented in the aftermath of the recent financial crisis.Furthermore, SMEs productivity has not changed post stricter bank regulations. Overall,the impact from different sources of funding on productivity is rather limited.The third essay explores firm formation by migrants with a STEM background. Theresult shows that native born STEM workers have a higher probability to form firmsrelative to migrants. Further categorization of migrants shows that refugees are morelikely to become entrepreneurs than EU-labour migrants. Overall, entrepreneurial migrantshave equal or higher predicted income in comparison to native born STEM entrepreneurs.The fourth essay analysis wage effects from changing work tasks using a tasked-basedapproach where workers are mapped in a two dimensional model classified by their cognitiveand routine task content. The result shows clear signs of wage polarization. switchfrom routine and manual tasks to non routine cognitive task yields an average wage premiumof about 2-6%. More importantly, while the gap was 1-5% in the beginning of theperiod, it increased to 10-13% at the end of the period. The result suggest that adaptingnew production technology and innovations to complement analytical skills has a higherand increasing marginal productivity compared to technologies aimed to replace or complementroutinized and manual work tasks. The period of this study is associated withseveral so-called breakthrough technologies such as, computerization, robotization, digitalizationand the introduction of IT technology.

  • Public defence: 2019-05-09 10:00 Kollegiesalen, Stockholm
    Sophonrat, Nanta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pyrolysis of mixed plastics and paper to produce fuels and other chemicals2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    As the world population and economy grow, higher consumption results in higher waste packaging, plastics and paper residues. Pyrolysis offers a way to recover fuels and other chemicals from this waste fraction. By applying heat to these materials in the absence of oxygen, pyrolysis process can convert these feedstocks into more valuable products in the forms of gas, liquid and char.

    One important issue in the pyrolysis process which requires an investigation is the interactions between the feedstocks which consist of cellulose as the main component of paper and different types of plastics. Regarding this topic, 3 subtopics were investigated which are: the effect of mixing methods on the co-pyrolysis products, the interactions between the plastics and cellulose, and the formation of H, OH and water during cellulose pyrolysis. All these experimental investigations were based on microscale pyrolysis experiments using Py-GC/MS technique.

    In the first work, polyethylene and cellulose were mixed by melting and by putting side-by-side. It was found that some interactions occurred during co-pyrolysis of these materials which slightly altered the yields of some anhydrosugars, aldehydes and ketones when the two feedstocks were mixed together by melting. Nevertheless, the main pyrolysis products from each feedstock were not affected. 

    In the second study, the investigation continues on the interactions between different types of plastics (PE, PP, PS, PET) and cellulose. By using Py-GC×GC/MS, a good separation of the mixed pyrolysis products could be achieved, thus assisting the analysis. It was found that although the main pyrolysis products from each feedstock were not affected by the co-pyrolysis, small interactions occurred such that the interactions between different plastics were more pronounced than the interactions between plastics and cellulose. Nevertheless, some hydrogen transfer reactions occurred when PS was co-pyrolyzed with cellulose. However, the source of hydrogen was not clear.

    Therefore, the investigation on the formation of H and OH radicals during cellulose pyrolysis was performed. This work combined first-principle calculations with experimental investigations. The author of the thesis was responsible for the experimental part. It was found from the first-principle calculations that it is energetically more favorable for the generation of a pair of H and OH radicals with subsequence formation of water than to generate a single radical because the formation of a double bond on the resulting cellulose helps stabilize the structure. With Gibbs free energy calculations, it was predicted that the water would be released at 280 °C. This agree well with the experimental findings from multistep pyrolysis of cellulose in Py-GC/MS which showed that water was generated at two different temperature ranges with the first peak around 280 °C.

    As the interactions between the feedstocks during co-pyrolysis do not much improve the liquid products’ properties, and the nature of the products produced from plastics and paper pyrolysis are significantly different; it might be more beneficial to separate the pyrolysis products from the two feedstocks. Moreover, the hydrocarbons produced from plastics pyrolysis and the oxygenated products from paper pyrolysis require different upgradation methods. Stepwise pyrolysis was then proposed to produce and collect these two products separately. With simulated feedstock mixtures (PE, PS, cellulose) and real waste fractions which are paper rejects, it was successfully demonstrated that the stepwise pyrolysis with a temperature of the first step of 300-350 °C and a temperature of the second step of 500 °C could be used to produce two products streams as previously described. However, an optimization of the process and further investigations on product properties and upgradation are still required.

    As a continuation on the investigation of the stepwise pyrolysis, an upgradation of the products from the first pyrolysis step was studied. When PVC plastic is present in the feedstock, dehydrochlorination of PVC occurs in the temperature range of the first pyrolysis step together with the pyrolysis of cellulose. Calcium oxide (CaO) was then tested for the simultaneous adsorption of HCl and reforming of cellulose pyrolysis products. The experiments were performed in a two-stage reactor system which was a pyrolysis reactor connected in series to a catalytic reactor containing CaO. It was found that the catalytic temperature should be between 300-350 °C because the desorption of HCl occurred when the temperature was higher than 400 °C. This was partly due to a reaction between water and CaCl2 which caused the desorption of HCl.

    From all the studies, stepwise pyrolysis has a great potential to produce fuels and other chemicals from mixed plastics and paper. Further investigations are needed to develop, evaluate and realize this promising process.

  • Zhang, Xinhai
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Embedded Control Systems.
    Automated Support for the Architecting of Distributed Embedded Systems: Methods and Analysis for Industrial Adoption2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The architecture design complexity of modern embedded systems, such as in the automotive domain, is growing due to the rapidly evolved functionalities, the increasing amount of interactions between functions and computation nodes, and the stringent extra-functional requirements. Architecture design is crucial since it affects nontrivial system properties such as safety, cost, performance of functionalities and also the development time. An important enabler to deal with this complexity is to provide computer aided architecture design. This thesis focuses on such support for Design Space Exploration (DSE), relying on a model-based design (MBD) environment.

    The goal of this thesis is to improve the industrial adoption of DSE methods to facilitate the architecture design of distributed embedded systems in the automotive industry. The main contributions of this thesis are as follows: (1) Applying architecture recovery in the automotive industry to extract architecture models from legacy ECU source code. The recovered architecture models can be used to facilitate system understanding, to verify the software implementation against its specification and also to enable DSE for architecture design. (2) A systematic gap analysis was conducted between the state-of-the-art DSE methods and the industrial needs, through literature studies and interviews with experienced system architects. Identified gaps are analyzed from the following perspectives: Architecting scenarios, architectural decisions, quality attributes, cost model, procurement strategy, system variability and functional safety. (3) A new problem formulation was proposed to reduce the design space by utilizing the features of evolutionary architecting and the AUTOSAR layered architecture. (4) In order to enhance the flexibility of the DSE methods by enabling the customizability of the architectural constraints, an automatic transformation method is proposed to translate formally described architectural constraints into the corresponding mixed integer linear programming(MILP) constraints, commonly used for DSE. (5) This thesis also investigates the potential impacts of vehicular communication on the future architecture of automotive embedded systems from the timing perspective through a case study to enable a commercial truck with cooperative driving functionalities. The receiving bias problem was identified during the case study and effective architectural solutions were proposed. The case study also showed that the adoption of vehicular communication would not have significant architectural impacts in terms of timing.

  • Public defence: 2019-05-10 09:30 Sal B, Stockholm
    Roozbeh, Amir
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS. Ericsson Research.
    Toward Next-generation Data Centers: Principles of Software-Defined “Hardware” Infrastructures and Resource Disaggregation2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The cloud is evolving due to additional demands introduced by new technological advancements and the wide movement toward digitalization. Therefore, next-generation data centers (DCs) and clouds are expected (and need) to become cheaper, more efficient, and capable of offering more predictable services.

    Aligned with this, we examine the concept of software-defined “hardware” infrastructures (SDHI) based on hardware resource disaggregation as one possible way of realizing next-generation DCs. We start with an overview of the functional architecture of a cloud based on SDHI. Following this, we discuss a series of use-cases and deployment scenarios enabled by SDHI and explore the role of each functional block of SDHI’s architecture, i.e., cloud infrastructure, cloud platforms, cloud execution environments, and applications.

    Next, we propose a framework to evaluate the impact of SDHI on techno-economic efficiency of DCs, specifically focusing on application profiling, hardware dimensioning, and total cost of ownership (TCO). Our study shows that combining resource disaggregation and software-defined capabilities makes DCs less expensive and easier to expand; hence they can rapidly follow the exponential demand growth. Additionally, we elaborate on technologies behind SDHI, its challenges, and its potential future directions.

    Finally, to identify a suitable memory management scheme for SDHI and show its advantages, we focus on the management of Last Level Cache (LLC) in currently available Intel processors. Aligned with this, we investigate how better management of LLC can provide higher performance, more predictable response time, and improved isolation between threads. More specifically, we take advantage of LLC’s non-uniform cache architecture (NUCA) in which the LLC is divided into “slices,” where access by the core to which it closer is faster than access to other slices. Based upon this, we introduce a new memory management scheme, called slice-aware memory management, which carefully maps the allocated memory to LLC slices based on their access time latency rather than the de facto scheme that maps them uniformly. Many applications can benefit from our memory management scheme with relatively small changes. As an example, we show the potential benefits that Key-Value Store (KVS) applications gain by utilizing our memory management scheme. Moreover, we discuss how this scheme could be used to provide explicit CPU slicing – which is one of the expectations of SDHI  and hardware resource disaggregation.

  • Public defence: 2019-05-17 13:00 Ka-Sal B (Sal Peter Weissglas), Stockholm
    Ivanisevic, Nikola
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Circuit Design Techniques for Implantable Closed-Loop Neural Interfaces2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Implantable neural interfaces are microelectronic systems, which have the potential to enable a wide range of applications, such as diagnosis and treatment of neurological disorders. These applications depend on neural interfaces to accurately record electrical activity from the surface of the brain, referred to as electrocorticography (ECoG), and provide controlled electrical stimulation as feedback. Since the electrical activity in the brain is caused by ionic currents in neurons, the bridge between living tissue and inorganic electronics is achieved via microelectrode arrays. The conversion of the ionic charge into freely moving electrons creates a built-in electrode potential that is several orders of magnitude larger than the ECoG signal, which increases the dynamic range, resolution, and power consumption requirements of neural interfaces. Also, the small surface area of microelectrodes implies a high-impedance contact, which can attenuate the ECoG signal. Moreover, the applied electrical stimulation can also interfere with the recording and ultimately cause irreversible damages to the electrodes or change their impedance. This thesis is devoted to resolving the challenges of high-resolution recording and monitoring the electrode impedance in implantable neural interfaces.

    The first part of this thesis investigates the state-of-the-art neural interfaces for ECoG and identifies their limitations. As a result of the investigation, a high-resolution ADC is proposed and implemented based on a ΔΣ modulator. In order to enhance performance, dynamic biasing and area-efficient switched-capacitor circuits were proposed. The ΔΣ modulator is combined with the analog front-end to provide a complete readout solution for high-resolution ECoG recording. The corresponding chip prototype was fabricated in a 180 nm CMOS process, and the measurement results showed a 14-ENOB over a 300-Hz bandwidth while dissipating 54-μW.

    The second part of this thesis expands upon the well-known methods for impedance measurements and proposes an alternative digital method for monitoring the electrode-tissue interface impedance. The proposed method is based on the system identification technique from adaptive digital filtering, and it is compatible with existing circuitry for neural stimulation. The method is simple to implement and performs wide-band measurements. The system identification was first verified through behavioral simulations and then tested with a board-level prototype in order to validate the functionality under real conditions. The measurement results showed successful identification of the electrode-electrolyte and electrode-skin impedance magnitudes.

  • Public defence: 2019-05-07 10:00 Kollegiesalen, Stockholm
    Nikouie, Mojgan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Design, Construction and Evaluation of a StackedPolyphase Bridges Converter for Integrated ElectricDrive Systems in Automotive ApplicationsMOJGAN NIKOUIEDoctoral ThesisStockholm, Sweden2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents a new concept for integration of the electricdrive system, specifically for electric and hybrid electric vehicle applications.The topology introduces an integration between the so-calledstacked polyphase bridges (SPB) converter and fractional-slot concentratedpermanent-magnet synchronous machine. The SPB converter iscomprised of an arbitrary number of submodules that are connected inseries to a dc-source voltage. A very compact integrated electric drivesystem is gained by the integration. Several advantages are potentiallygained from the concept, such as considerably shortening the powercables interconnecting the converter with the machine and as well asreduction in terms of electromagnetic interference, weight, and size.The principal focus of the thesis is on the design, construction, andcontrol of the SPB converter. Three different generations for the SPBconverter, all with four submodules, have been developed within theproject. In the first two generations, a submodule consists of a two-layerprinted circuit board (PCB) including both power and control circuits,whereas in the third generation, each submodule has separate powerand control boards. The power circuit is a conventional two-level threephaseconverter. In the third generation, the power PCBs can handlean rms current of 100 A and a dc-link voltage of 100 V.Along with the design of the converter, control algorithms have beendeveloped. A conventional proportional–integral (PI) current controlleris implemented on the microprocessor of each control board, on whichouter control loops are added. One important contribution concerningthe control is the stability analysis and balancing controller designresulting thereof. Since the submodules are series connected to the dcsourcevoltage, it is essential to ensure that the total voltage is sharedequally among the submodules.Secondly, a study of the SPB converter under fault is made. It is assumedthat one submodule is facing a short- or open-circuited powertransistor and the behavior of the converter is studied. A proposal fora safe way of short circuiting the faulty submodule is presented.Finally, torque ripple minimization is discussed. It is shown that usingan estimator for the flux linkage harmonics in the machine as well asadding a resonant part to the PI current controller can be an efficientmethod to suppress the ripple.

  • Public defence: 2019-05-06 13:00 FA31, Stockholm
    Petrou, Georgia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Investigating mucin interactions with diverse surfaces for biomedical applications2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mucous membranes are covered with mucus, a viscoelastic hydrogel that plays an essential role in their protection from shear and pathogens. The viscoelasticity of mucus is owing to mucins, a group of densely glycosylated proteins. Mucins can interact with a wide range of surfaces; thus, there is big interest in exploring and manipulating such interactions for biomedical applications. This thesis presents investigations of mucin interactions with hydrophobic surfaces in order to identify the key features of mucin lubricity, as well as describes the development of materials that are optimized to interact with mucins.


    In Paper I we investigated the domains which make mucins outstanding boundary lubricants. The results showed that the hydrophobic terminal domains of mucins play a crucial role in the adsorption and lubrication on hydrophobic surfaces. Specifically, protease digestion of porcine gastric mucins and salivary mucins resulted in the cleavage of these domains and the loss of lubricity and surface adsorption. However, a “rescue” strategy was successfully carried out by grafting hydrophobic phenyl groups to the digested mucins and enhancing their lubricity. This strategy also enhanced the lubricity of polymers which are otherwise bad lubricants.


    In Paper II we developed mucoadhesive materials based on genetically engineered partial spider silk proteins. The partial spider silk protein 4RepCT was successfully functionalized with six lysines (pLys-4RepCT), or the Human Galectin-3 Carbohydrate Recognition Domain (hGal3-4RepCT). These strategies were aiming to either non-specific electrostatic interactions between the positive lysines and the negative mucins, or specific binding between the hGal3 and the mucin glycans. Coatings, fibers, meshes and foams were prepared from the new silk proteins, and the adsorption of porcine gastric mucins and bovine submaxillary mucins was measured, demonstrating enhanced adsorption.


    The work presented demonstrates how mucin-material interactions can provide us with valuable information for the development of new biomaterials. Specifically, mucin-based and mucin-inspired lubricants could provide desired lubrication to a wide range of surfaces, while our new silk based materials could be valuable tools for the development of mucosal dressings.

  • Public defence: 2019-05-10 10:00 FA-31, Stockholm
    Kianirad, Hoda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Studies on Domain Dynamics in Nonlinear Optical Ferroelectric Oxide Crystals2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nonlinear optical frequency conversion is the key technology for modifying laser output radiation, in order to target specific applications. The most powerful technique to obtain tailored second-order nonlinear interactions is the quasi-phasematching (QPM) approach. QPM is based on periodic modulation of the medium’s nonlinearity and allows versatile and efficient frequency conversion in the whole transparency region of the material. QPM is commonly implemented in ferroelectric oxide crystals by periodically inverting the spontaneous polarization, so-called, periodic poling. However, in order to achieve QPM structures of practical relevance, both the optical properties of the material and the domain engineering techniques have to be suitable for the targeted nonlinear interaction.

    Rb-doped KTiOPO4 (RKTP) and vapor-transport-equilibrated stoichiometric LiTaO3 (VTE-SLT) are two of the most promising ferroelectric oxides used for nonlinear optics. The former is suitable for high peak-power applications and for engineering of QPM devices with sub-µm periodicity. The latter shows a short cut-off wavelength with low linear absorption, which makes it very attractive for UV-light generation. However, in order to fully exploit the potential of these two materials, it is of utmost importance to understand the domain dynamics and stability from a fundamental point of view, as well as to investigate ways to overcome their limitations.

    This thesis presents studies on domain dynamics and stability in these two materials. A novel method for periodic poling of RKTP has been investigated. The method, based on using a micro-structured silicon chip as the contact electrode, has been used to fabricate periodically poled RKTP crystals with 9.01 µm period. The samples became well-poled and showed high conversion efficiency for second harmonic generation. The domain dynamics, when the silicon stamp was used as an electrode were studied, showing potential for short-pitch poling and complex patterning.

    Furthermore, the domain stability in RKTP during thermal annealing at high temperatures was investigated. The results show anisotropic domain wall motion, with severe domain contraction along the crystallographic b-axis when the periodicity was reduced. A technique to suppress this domain contraction was developed based on dicing away the edges of the QPM grating so that the domain b-faces terminate in air. This gave excellent results for a broad range of periodicities.

    Studies of the domain stability of periodically poled VTE-SLT during chemical etching were performed by on-line second harmonic generation, and optical microscopy. The results show that wet etching directly after poling leads to domain-wall motion, resulting in back-switching or domain merging. 

    Furthermore, the domain wall motion induced by electron beam irradiation was investigated using a scanning electron microscope. It was found that domain switching strongly depends on the ratio of secondary electrons to incident electrons. These results are discussed in terms of electron beam and screening charges interaction.

  • Wallmark, Oskar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nikouei Harnefors, Mojgan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    DC-link and machine design considerationsfor resonant controllers adopted in automotive PMSM drivesIn: Article in journal (Refereed)
  • Nikouie, Mojgan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Wallmark, Oskar
    Harnefors, Lennart
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Torque-Ripple Minimization for Permanent-MagnetSynchronous Motors Based on Harmonic Flux Estimation2018Conference paper (Refereed)
    Abstract [en]

    This paper presents a control algorithm to reduce the torque ripple in permanent-magnet synchronous motors. This control algorithm is based on the on-line estimation of harmonic flux linkage. Together with the online estimation of the flux linkage, a proportional–integral–resonant controller is introduced to suppress the torque ripple.

  • Nikouie, Mojgan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Zhang, Hui
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Highly integratedelectric drives system for tomorrow’s EVs and HEVs2017Conference paper (Refereed)
    Abstract [en]

    This paper presents an ultra-compact integratedelectric drive prototype. The prototype illustrates the integrationof a fractional slot concentrated winding (FSCW) electric motor,a stacked polyphase bridges (SPB) converter, the control boards,and the water cooling plates into a common housing. Thisintegrated prototype offers a high potential of compactness andcost reduction for electric and hybrid electric vehicles.

  • Ayyalasomayajula, Swarna Manjari
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Analysis of the South Korean Procedure for the Fuel Consumption and CO2 Emissions from Heavy Duty Vehicles. Sensitivity Analysis of the Fuel Consumption Deviation in Transient Cycles over Steady State Conditions.2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To meet the demands to reduce national energy consumption and greenhouse gas emission targets based on environmental policy, the Ministry of Trade, Industry, and Energy of Korea formed a research consortium consisting of government agencies and academic research institutions to establish the first fuel efficiency standards for Heavy-duty commercial vehicles (HDV). The standards are expected to be introduced at the earliest in 2020 as Phase 1 of the plan. Research is also in progress to derive regulation measures for CO2 emissions from heavy-duty vehicles. The test-driving cycle selected for comparison with current road situations is Korean-World Harmonized Vehicle Cycle (K-WHVC) for all heavy-duty vehicles. The Heavy duty vehicle Emission Simulator (HES) is used to simulate the fuel consumption and subsequent CO2 emissions for the specified HDV. The power demand can be too high for the HDV model during full payload as the simulated velocity could not reach the demanded velocity in an instance. HES simulates the fuel consumption to ±1.5% deviation in the transient part of the cycle. It over estimates the fuel consumption to 9% deviation in rest of the cycle. This report also studies the factors that are affecting the fuel consumption during the transient cycle on an engine level and estimates of fuel consumption under transient conditions on an engine level. The deviations of the transient cycle (WHTC of the DC-13 164 engine) from the quasi-stationary values (interpolated steady state values of DC-13 164 engine), which are considered as the transient characteristics of these parameters, are studied to estimate the factors affecting the fuel consumption. It is observed that the change in the fuel flow varies inversely with change in the air fuel ratio and directly with change in the boost pressure. The equations describing this behaviour of air fuel ratio with change of fuel flow is calculated. Comparison of the model/equation results with measurements on both the steady state conditions and a transient cycle (WHTC) is done. It is observed that the percentage deviation of fuel consumption from transient to quasi-stationary flow for the DC-13 164 engine is 1.1 percent where as from transient to corrected fuel flow is 0.4 percent.

  • Public defence: 2019-05-03 10:00 D2, Stockholm
    Müller, Matias
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Regret and Risk Optimal Design in Control2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Engineering sciences deal with the problem of optimal design in the face of uncertainty. In particular, control engineering is concerned about designing policies/laws/algorithms that sequentially take decisions given unreliable data.

    This thesis addresses two particular instances of optimal sequential decision making for two different problems. The first problem is known as the H-norm (or l2-gain, for LTI systems) estimation problem, which is a fundamental quantity in control design through the small gain theorem. Given an unknown system, the goal is to find the maximum l2-gain which, in a model-free approach, involves solving a sequential input design problem. The H-norm estimation problem (or simply "gain estimation problem") is cast as the composition of a multi-armed bandit problem generating data, and an optimal estimation problem given that data. It is shown that the separation of the gain estimation problem into these two sub-problems is optimal in a mean-square sense, as the expected estimation error asymptotically matches the Cramér-Rao lower bound.

    In the second part of the thesis, we address the problem of risk-coherent optimal control design for disturbance rejection under uncertainty, where optimality is studied from an H2 and an H sense. We consider a parametric model for the plant and the noise spectrum, where the modeling error between the model and the real system is uncertain. This uncertainty is condensed in a probability density function over the different realizations of the parameters defining the model. We use this information to design a controller that minimizes the risk of falling into poor closed-loop performance within a financial theory of risk framework. A systematic approach for the design of H2- and H-optimal controllers is proposed in terms of a quadratically-constrained linear program and a semi-definite program, respectively. An interesting application to H2-optimal design under covert attacks is also developed.

  • Public defence: 2019-06-05 10:00 Q2, Stockholm
    Schillinger, Philipp
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. Bosch Center for Artificial Intelligence.
    Specification Decomposition and Formal Behavior Generation in Multi-Robot Systems2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Autonomous robot systems are becoming increasingly common in service applications and industrial scenarios. However, their use is still mostly limited to rather simple tasks. This primarily results from the considerable effort that is required to manually program the execution plans of the robots. In this thesis, we discuss how the behavior of robots can be automatically generated from a given goal specification. This forms the basis for providing formal guarantees regarding optimality and satisfaction of the mission goal specification and creates the opportunity to deploy these robots in increasingly sophisticated scenarios. Well-defined robot capabilities of comparably low complexity can be developed independently from a specific high-level goal and a behavior planner can then automatically compose them to achieve complex goals in a verifiably correct way.

    Intelligent coordination of a robot team can highly improve the performance of a system, but at the same time, considering multiple robots introduces significant additional planning complexity. To address the complexity, a framework is proposed to efficiently plan actions for multi-robot systems. The generated behavior of the robots is guaranteed to fulfill complex, temporally extended, formal mission specifications posed to the team as a whole. To achieve this, several challenges are addressed such as decomposition of a specification into tasks, allocation of tasks to robots, planning of actions to execute the assigned tasks, and coordination of action execution. This enables the combination of heterogeneous robots for automating tasks in a wide range of practically relevant applications.

    The proposed methods determine efficient actions for each robot in the sense that these actions are optimal in the absence of execution uncertainty and otherwise, improve the solution performance over time based on online observations. First, to plan optimal actions, an approach called Simultaneous Task Allocation and Planning is proposed to utilize the interplay of allocation and planning based on automatically identified, independently executable tasks. Second, to improve performance in the presence of stochastic actions, a Hierarchical LTL-Task MDP is proposed to combine auction-based allocation with reinforcement learning to achieve the desired performance with feasible computational effort. Both approaches of the presented framework are evaluated in the considered use case areas of service robotics and factory automation. The results of this thesis enable to plan correct-by-construction behavior from expressive specifications in more complex and realistic scenarios than possible with previous approaches.

  • Public defence: 2019-05-03 09:00 Air & Fire, Solna
    Jess, David Unnersjö
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics.
    High-resolution Imaging of Cleared and Expanded Kidney Tissue Samples2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The kidney is one of the most important and complex organs in the humanbody with the task of filtering hundreds of litres of blood daily. It is responsiblefor the salt and acid/base balance in the body, as well as secretinghormones important for red blood cell production and blood pressure regulation. Kidney disease is one of the fastest growing causes of death in the modern world, and this motivates extensive research for better understandingthe function of the kidney in both health and disease. Kidney failure or end stage renal disease (ESRD) is irreversible and requires treatment with dialysisor transplantation. Some of the most important cellular structures for blood filtration in the kidney are of very small dimensions (below 200 nanometers), and thus electron microscopy has previously been the only method with high enough resolution to study the morphology and topology of these minute structures. In three studies included in this thesis, we show that the finest elements of the kidney can now be resolved using different light microscopy techniques. In study 1, we show that by combining optical clearing with STED microscopy, protein localizations in the slit diaphragm of the kidney can be resolved, with widths around 75 nanometers. In study 3, a novel sample preparation method, expansion microscopy, is utilized to isotropically expand kidney tissue samples in space. Expansion improves the effective resolution by a factor of 5, making it possible to resolve podocyte foot processes and the slit diaphragmusing diffraction-limited confocal microscopy. We also show that by combining expansion microscopy and STED microscopy, the effective resolution can be improved even further (<20 nm). In our most recent work, study 5, we apply a simplified, moderate tissue swelling protocol which together with optimization of the confocal imaging provides sufficient resolution to resolve foot processes and parts of the filtration barrier. This new protocol is fast and technically simple, making it ideal for routine use, such as for future clinical pathology. In collaboration with kidney researchers, we have applied both STED microscopy and expansion microscopy to various disease models, showing that these tools can be used to both visualize and quantify pathologies occurring in different parts of the glomerular filtration barrier (GFB). In study 2, STED microscopy in combination with optical clearing is used to study the localization of Coro2b in secondary foot processes in both mouse and human tissue. In two ongoing studies with preliminary results presented in the thesis, we use STED microscopy and optical clearing to study the pathogenesis of focal segmental glomerulosclerosis (FSGS) by the use of genetic mouse models. Based on STED images, we extract different morphological parameters from foot processes and the glomerular filtration barrier (GFB) at different stages of the disease. In study 4, we apply a tissue expansion protocol to answer questions about the phenotype seen in podocytes where the mediator complex subunit 22 (Med22) is inactivated. By inactivating Med22 in a transgenic mouse line with cytosolic expression of tdTomato in podocytes, we saw strong indications that the vesicle-like structures seen in EM micrographs were indeed intracellular vesicles and not dilated sub-podocyte space. In summary, the work presented in this thesis has contributed to the development of a new toolbox for imaging renal ultra-structure using light microscopy, a field previously reserved for electron microscopy.

  • Public defence: 2019-05-03 10:00 Ka-Sal B (Sal Peter Weissglas), Kista
    Hou, Shuoben
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Silicon Carbide High Temperature Photodetectors and Image Sensor2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Silicon Carbide (SiC) has the advantages of ultraviolet (UV) sensing and high temperature characteristics because of its wide band gap. Both merits make SiC photodetectors very attractive in astronomy, oil drilling, combustion detection, biology and medical applications. Driven by the objective of probing the high temperature surface of Venus (460 °C), this thesis develops SiC photodetectors and an image sensor for extremely high temperature functions. The devices and circuits are demonstrated through the procedure of layout design, in-house processing and characterizations on two batches.

    The process flow has been optimized to be suitable for large scale integration (LSI) of SiC bipolar integrated circuits (IC). The improved processing steps are SiC dry etching, ohmic contacts and two-level metal interconnect with chemical-mechanical polishing (CMP). The optimized process flow is applied in the fabrication of discrete devices, a transistor-transistor logic (TTL) process design kit (PDK) and LSI circuits.

    The photodetectors developed in this thesis, including photodiodes with various mesa areas, a phototransistor and a phototransistor Darlington pair have stable characteristics in a wide temperature range (25 °C ~ 500 °C). The maximum operational temperature of the p-i-n photodiode (550 °C) is the highest recorded temperature accomplished ever by a photodiode. The optical responsivity of the photodetectors covers the spectrum from 220 nm to 380 nm, which is UV-only.

    The SiC pixel sensor and image sensor developed in this thesis are pioneer works. The pixel sensor overcomes the challenge of monolithic integration of SiC photodiode and transistors by sharing the same epitaxial layers and topside contacts. The pixel sensor is characterized from 25 °C to 500 °C. The whole image sensor circuit has 256 (16 ×16) pixel sensors and one 8-bit counter together with two 4-to-16 decoders for row/column selection. The digital circuits are built by the standard logic gates selected from the TTL PDK. The image sensor has 1959 transistors in total. The function of the image sensor up to 400 °C is verified by taking basic photos of nonuniform UV illumination on the pixel sensor array.

    This thesis makes an important attempt on the demonstration of SiC opto-electronic on-chip integration. The results lay a foundation on the development of future high temperature high resolution UV image sensors.

  • Dahlqvist, Caroline
    et al.
    KTH, School of Engineering Sciences (SCI).
    Eriksson, Hanna
    KTH, School of Engineering Sciences (SCI).
    Night-Time Observations of Earth: Satellite Orbit Modied for UHECR Observations2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Particles with energies higher than 3. 10.19 eV are generally referred to as Ultra- High Energy Cosmic Rays (UHECRs) and their sources are currently unknown. The observations of these particles are performed during the night from ground observatories or telescopes mounted on stratospheric balloons or, in the near future, from the International Space Station (ISS). In this report, different orbit types are analysed and compared with the ISS in terms of the duration of the sub-point in night-time (umbra), the observed area on the ground in umbra and estimations of the observable number of events.

  • Agostini Fantini, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Izaguirre Carbonell, Javier
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    GIS-Based approach to estimate the energy requirements of the post-harvest activities in Souss-Massa basin in Morocco2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Over the last decades the Moroccan agriculture has passed through a complete transformation: due to the low workforce cost and its favourable climate, the sector has attracted the attentions of national and foreign investment and thus has expanded rapidly. Among the different productions, tomatoes proved to be one of the most profitable, generating 4.867 billion dirhams in 2016 from exports. In order to remain competitive and attractive, the sector needs to be constantly monitored and controlled: abuses of the environment and of available resources may affect or even compromise the future of the Moroccan agriculture. Energy in particular has a remarkable role and has to be analysed in order to quantify its impact over costs and environment. The aim of this study is to build a GIS-based model of tomato’s postharvest system and study the agriculture and energy nexus interactions in the Souss-Massa region. Post harvesting activities such as: Transportation, conditioning, packaging, storing and transformation of tomato, occurs within Souss-Massa’s geographical boundaries and have been the focus of in this study. Results of current system highlight the dominance of packaging activity as the main energy consumer with 77%, followed by storing, transportation and transformation with 14 %, 6% and 3% respectively. In terms of cost the transportation becomes the most relevant activity due to the cost of fuels and transport conditions. Energy costs and wastes in transportation represent 15% of the local revenues (9% Transportation, 5% Packaging and 1% Storing). Four different scenarios about the future situation have been implemented to measure the possible impact of changes in the different activities: Business as Usual (BAU), Transport Efficiency (TE), Waste Reduction (WR) and Renewable Penetration (RP). -3- In BAU current trends have been followed to forecast the total production, the export and the power generation. In TE trucks with bigger capacity have been implemented and in WR refrigeration is considered in every transport stage. Finally, in RP higher renewable penetration has been considered

  • Ooi, S. W.
    et al.
    Ramjaun, T. I.
    Hulme-Smith, C.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Morana, R.
    Drakopoulos, M.
    Bhadeshia, H. K. D. H.
    Designing steel to resist hydrogen embrittlement Part 2: precipitate characterisation2018In: Materials Science and Technology, Vol. 34, no 14, p. 1747-1758Article in journal (Refereed)
    Abstract [en]

    A novel, low-alloy steel has been designed for use in the oil and gas industry. Its high strength and hydrogen trapping potential are derived from a martensitic microstructure containing a dispersion of fine vanadium–molybdenum alloy carbides that evolve during tempering. In this secondpaper,theeffectofquenchratefromaustenitisationandtemperingconditionsareinvestigated with respect to the microstructure. The alloy loses its tempering resistance following slow-cooling from austenitisation as a result of MC precipitation, leading to vanadium depletionandsignificantM2Ccoarsening.Thisispredictedusingcomputersimulationandconfirmed byhighenergyX-raydiffraction,combinedwithelectronmicroscopy.

  • Hallberg, Maria
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Hallme, Elin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Introducing a central receiver system for industrial high-temperature process heat applications: A techno-economic case study of a large-scale CST plant system in a South African manganese sinter plant2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis was to investigate the potential for introducing a concentrating solar thermal (CST) central receiver plant system based on flexible heliostats - HelioPods - to provide high-temperature process heat in industrial applications. A CST plant system was designed in MATLAB, optically simulated for three design days in the ray-tracing software Tonatiuh and further analyzed in MATLAB by interpolating the results for each hour of the year. A case study was made on introducing a CST plant system based on HelioPods in a South African manganese sinter plant. The study included an investigation of the profitability of up- and downsizing the heliostat field annually with fluctuating heat demand. A circular heliostat field was modelled for the chosen location. The final field had a radius of 53 meters with the receiver located 60% from the field centre. The storage size was 16 demand hours and 17 plants were required. The results showed that 88% of the annual heat demand could be covered by solar heat in the design year. The marketing approach used for the following years was that the heat demand covered by solar heat should never be below the share at the first year, despite the predicted fluctuations in demand. Thus, a minimum solar share of 88% was used as a strategy for annual up- and downsizing of the fields throughout the investigated period of 25 years. That resulted in a field radius differing between 52 and 55 meters.

    The payback period of the final system was 4.35 years, the NPV was 54.33 MUSD over a period of 25 years and the LCOH was 35.39 USD/MWht. However, it was found that the profitability of the system was sensitive to the different scenarios for predicted future diesel prices, this since the pricing of the solar heat was set to 90% of the diesel price. The results in this thesis show that a CST plant system based on HelioPods is a suitable solution to supply high-temperature process heat to industrial applications. It also shows that the HelioPods can unlock potential for flexibility with changing production patterns in the industry of implementation. The results from the study can be used also for other industries with similar temperature range and heat demand. Thus, it could be argued that the implementation of a HelioPod based CST plant system also can be suitable for other industries located in high-DNI areas with dependency on conventional fuels and steady production throughout the whole day.

  • Li, Ke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Experimental Study of Heat Transfer Coefficient and Film Cooling Effectiveness2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the possibility to evaluate the film cooling thermal performance on flat plate using Thermochromic Liquid Crystal. After an introduction of the basic concept and background of gas turbine blades film cooling and Thermochromic Liquid Crystal, a thorough explanation of four methods is presented. Dimensional or similarity analysis is implemented to build relationship between real engine and laboratory model. Also, the Reynolds number and Blowing ratio are the fundamental of test object design and TLC selection. This study illustrated the layout of the test rig and corresponding setups, and the following part explains the data collection system and image processing MATLAB script which is vital for the success of data extraction. The least square method is applied to figure time-series optimal solution in solver. All the experiments are conducted at near room temperature as opposed to the extremely high gas turbine exhausted gas, including two calibration test and one heat transfer experiment. The heat transfer coefficient and film cooling effectiveness are the target objective through the entire project. By comparison with a similar experiment in a literature, the outcomes partially validated the film cooling performance under the pre-set flow and thermal condition and the Liquid Crystal thermography technique is proved to be a trustworthy method to mapping heat transfer surface.

  • Tomic, David
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Service Aware Traffic Distribution in Heterogeneous A2G Networks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Airplanes have different ways to connect to the ground, including satellite air-to-ground communication (SA2GC) and direct air-to-ground communication (DA2GC). Each connection/link offers a different varying amount of transmission capacity over flight time. The traffic generated in the airplane must be forwarded/sent to ground over the available links. It is however not clear how the traffic should be forwarded so that traffic quality of service (QoS) requirements are met. The thesis at hand considers this question, and implements an algorithm handling the forwarding decision with three different forwarding schemes. Those consider traffic parameters in calculating a value assigned to each traffic flow, over a combination of priority, delay requirement and the number of times a traffic flow is dropped. The forwarding algorithm relies on proposed in-flight broadband connectivity (IFBC) network traffic and air-to-ground (A2G) link models, which aim at approximating the network environment of future IFBC networks. It is shown that QoS requirements of traffic flows in terms of packet loss and delay cannot be satisfied with capacities offered by current DA2GC and SA2GC technology. For a future scenario, with higher assumed link capacities, the QoS requirements are met to a higher extent. This is shown in lower packet loss and delay experienced by the respective traffic flows. Further, it is shown that the performance can be improved with specific forwarding schemes used by the forwarding algorithm. It is also investigated how a web cache can be used as a fallback technology. For this a required web cache hit rate is found, which should be high enough to offload the network with content served from the cache. Overall, the thesis aims at proposing an efficient traffic forwarding technique, and at giving insight into an alternative if this technique fails.

  • Wenjing, Wei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Gyllenram, Rutger
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Samuelsson, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Assesment of Scrap-based Production for Low Phosphorus Stainless Steel2018Conference paper (Refereed)
    Abstract [en]

    Low phosphorous contents in austenitic stainless steels favours a resistance to stress corrosion cracking and reduces the susceptibility to hot cracking. An industrial problem is that phosphorous cannot be removed from chromium alloyed steels, since oxidation of chromium occurs before phosphorous oxidation. This brings a challenge for scrap-based stainless steelmakers since an accumulation of phosphorous in the steel cycle should be avoided. In this paper, the effects of the phosphorus content in stainless steel scrap have been studied when producing AISI 304-type of stainless steel with low phosphorus level demands. These steels are often produced by melting scrap by using the EAF-AOD route. The influence of scrap with varied phosphor contents on steels has been assessed by using RAWMATMIX®, which is a web-based raw material optimization software.

  • Stigsson, Martin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. SKB, Swedish Nuclear Fuel and Waste Management Co, Solna, Sweden.
    Munier, Raymond
    SKB, Swedish Nuclear Fuel and Waste Management Co, Solna, Sweden.
    Orientation uncertainty goes bananas: An algorithm to visualise the uncertainty sample space on stereonets for oriented objects measured in boreholes2013In: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 56, p. 56-61Article in journal (Refereed)
    Abstract [en]

    Measurements of structure orientations are afflicted with uncertainties which arise from many sources. Commonly, such uncertainties involve instrument imprecision, external disturbances and human factors. The aggregated uncertainty depends on the uncertainty of each of the sources. The orientation of an object measured in a borehole (e.g. a fracture) is calculated using four parameters: the bearing and inclination of the borehole and two relative angles of the measured object to the borehole. Each parameter may be a result of one or several measurements. The aim of this paper is to develop a method to both calculate and visualize the aggregated uncertainty resulting from the uncertainty in each of the four geometrical constituents. Numerical methods were used to develop a VBA-application in Microsoft Excel to calculate the aggregated uncertainty. The code calculates two different representations of the aggregated uncertainty: a 1-parameter uncertainty, the ‘minimum dihedral angle’, denoted by Ω; and, a non-parametric visual representation of the uncertainty, denoted by χ. The simple 1-parameter uncertainty algorithm calculates the minimum dihedral angle accurately, but overestimates the probability space that plots as an ellipsoid on a lower hemisphere stereonet. The non-parametric representation plots the uncertainty probability space accurately, usually as a sector of an annulus for steeply inclined boreholes, but is difficult to express numerically. The 1-parameter uncertainty can be used for evaluating statistics of large datasets whilst the non-parametric representation is useful when scrutinizing single or a few objects.

  • Zhang, Cheng
    et al.
    State Key Laboratory of Bioreactor Engineering, East China University of Science, and Technology, Shanghai, China,2Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China.
    Hua, Qiang
    Applications of Genome-Scale Metabolic Models in Biotechnology and Systems Medicine: Application of GEMs2016In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 6, no January, article id 413Article in journal (Refereed)
    Abstract [en]

    Genome-scale metabolic models (GEMs) have become a popular tool for systems biology, and they have been used in many fields such as industrial biotechnology and systems medicine. Since more and more studies are being conducted using GEMs, they have recently received considerable attention. In this review, we introduce the basic concept of GEMs and provide an overview of their applications in biotechnology, systems medicine, and some other fields. In addition, we describe the general principle of the applications and analyses built on GEMs. The purpose of this review is to introduce the application of GEMs in biological analysis and to promote its wider use by biologists.

  • Misgeld, Olof
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Holzapfel, André
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Ahlbäck, Sven
    Dancing Dots - Investigating the Link between Dancer and Musician in Swedish Folk Dance2019Conference paper (Refereed)
    Abstract [en]

    The link between musicians and dancers is generally described as strong in many traditional musics and this holds also for Scandinavian Folk Music - spelmansmusik. Understanding the interaction of music and dance has potential for developing theories of performance strategies in artistic practice and for developing interactive systems. In this paper we investigate this link by having Swedish folk musicians perform to animations generated from motion capture recordings of dancers. The different stimuli focus on motions of selected body parts as moving white dots on a computer screen with the aim to understand how different movements can provide reliable cues for musicians. Sound recordings of fiddlers playing to the "dancing dot" were analyzed using automatic alignment to the original music performance related to the dance recordings. Interviews were conducted with musicians and comments were collected in order to shed light on strategies when playing for dancing. Results illustrate a reliable alignment to renderings showing full skeletons of dancers, and an advantage of focused displays of movements in the upper back of the dancer.

  • Mukhopadhyay, Sagnik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS. Computer Science Institute of Charles University, Prague, Czech Republic.
    Loff, Bruno
    Lifting Theorems for Equality.2019Conference paper (Refereed)
    Abstract [en]

    We show a deterministic simulation (or lifting) theorem for composed problems f ◦Eqn where the9 inner function (the gadget) is Equality on n bits. When f is a total function on p bits, it is easy to10 show via a rank argument that the communication complexity of f ◦Eqn is Ω(deg(f)·n). However,11 there is a surprising counter-example of a partial function f on p bits, such that any completion f012 of f has deg(f0) = Ω(p), and yet f ◦Eqn has communication complexity O(n). Nonetheless, we are13 able to show that the communication complexity of f ◦Eqn is at least D(f)·n for a complexity14 measure D(f) which is closely related to the AND-query complexity of f and is lower-bounded by15 the logarithm of the leaf complexity of f. As a corollary, we also obtain lifting theorems for the16 set-disjointness gadget, and a lifting theorem in the context of parity decision-trees, for the NOR17 gadget.18 As an application, we prove a tight lower-bound for the deterministic communication complexity19 of the communication problem, where Alice and Bob are each given p-many n-bit strings, with the20 promise that either all of the strings are distinct, or all-but-one of the strings are distinct, and they21 wish to know which is the case. We show that the complexity of this problem is Θ(p·n).

  • Sjöman, Martin
    et al.
    Textilhögskolan vid Högskolan i Borås.
    Svengren Holm, Lisbeth
    Textilhögskolan vid Högskolan i Borås.
    Radón, Anita
    Textilhögskolan vid Högskolan i Borås.
    Entreprenörskap och kreativitet i framgångsrika svenska modeföretag2013In: Kreativt kapital: Om ledning och organisation i kulturella och kreativa näringar / [ed] Emma Senström och Lars Strannegård, Stockholm: 8tto - Volante , 2013, p. 117-155Chapter in book (Other academic)
  • Basmaci, Benjamin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Improving indoor thermal comfort in residential buildings in Andean regions of Peru2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the Peruvian Andes, inadequate housing represents an important problem for the local rural people. Over 3000 meters above sea level, communities suffer from very low indoor temperatures this becomes an issue which affects the health and indoor thermal comfort of the building. At early winter mornings, outdoor temperatures can occasionally go down to -15°C and indoor temperatures can drop below zero. Previous work in the field has been done by the Pontifical Catholic University of Peru PUCP, to address thermal comfort in Langui, Peru involving participatory design techniques, multidisciplinary approaches and a focus on sustainability. Their most recent design is based on an attached passive solar heating system similar to a Trombe wall.

    The effect of housing environment on human health has been an acknowledged issue for many years. In the area, the occupants live with high levels of air infiltration, dirt floor (soil), simple windows, metallic or wood doors, roof most commonly made of corrugated metal sheets, adobe walls, no additional insulation attached and no house heating system. This thesis aims to contribute to a current body of research on thermal comfort and provide insights on how the building environment in Langui can be improved.

    The main objective is to improve thermal comfort in residential buildings in Andean regions of Peru. An improvement was made by installing a Heat Transfer Rocket which increased the temperature while the relative-humidity stayed steady. Overall, the study shows that indoor improvements can increase thermal comfort in Andean regions of Peru.

  • Hinders, Johan
    Universitetsbiblioteket, Stockholms universitet.
    Oväntat möte i biblioteket2011In: Kompassriktning: 2000-talet: Festkrift till Catarina Ericsson-Roos / [ed] Eva Enarsson, Leif Friberg, Wilhelm Widmark, Stockholm, 2011, p. 195-204Chapter in book (Other (popular science, discussion, etc.))
  • Hinders, Johan
    Arkeologiska forskningslaboratoriet, Institutionen för arkeologi och antikens kultur, Stockholms universitet.
    Combined Sulfur and Strontium analysis: a model for deeper understanding in mobility for a specific site?: Sulfur analysis on collagen results, compared to strontium analysis on enamel, from Frälsegården passage grave in Falbygden, Sweden.Manuscript (preprint) (Other academic)
    Abstract [en]

    Investigation of human movement in the past has been of great interest in archaeology. Direct measurements of past mobility have become possible through the application of strontium isotope analysis on human skeletal remains; during the last few years, a growing attention has been paid to the stable isotope of sulfur – δ34S. Not until now, there has been no attempt to compare the two methods: strontium analyses – 87Sr/86Sr – on hydroxylapatite, and δ34S- analyses on collagen; in analyzing the very same objects to track mobility patterns. 

       In this paper the outcome and conclusions of two different studies will be compared: one using the strontium isotope method and another on using the sulfur stable isotope method, both investigating material from Falbygden in western Sweden - a cultural and natural landscape with several unique features.

       This study shows that the differences between the two methods might cause different conclusions.

  • Gernandt, Niclas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Farhod, Jaser
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    JÄMFÖRELSE AV ATTITYDANALYS ALGORITMER FÖR SPELOMDÖMEN2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today there exist a huge amount of user created content in the shape of text from game reviews to opinions in microblogs like Twitter. To analyze this data could be of value for both companies and data scientists but remains to be very daunting. With the help of sentiment analysis this could be achieved automatically and save resources, but the question remains which algorithms have the best performance? With the help of a study and a couple of tests the most popular approaches in sentiment analysis could be compared by analyzing game reviews from the platform Steam. Through testing it has showed that machine learning based algorithms have the best performance and are easier to start with in comparison to lexicon-based approaches, which barely even reach the threshold for reliability in classifying reviews to be positive or negative. But it’s still important to plan and consider which algorithm one chooses for sentiment analysis as both approaches have their flaws and had a weak performance regarding sarcastic reviews.

  • Bore, Nils
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Torroba, Ignacio
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Folkesson, John
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Sparse Gaussian Process SLAM, Storage andFiltering for AUV Multibeam Bathymetry2018In: 2018 IEEE OES Autonomous Underwater Vehicle Symposium, 2018Conference paper (Refereed)
    Abstract [en]

    With dead-reckoning from velocity sensors,AUVs may construct short-term, local bathymetry mapsof the sea floor using multibeam sensors. However, theposition estimate from dead-reckoning will include somedrift that grows with time. In this work, we focus on long-term onboard storage of these local bathymetry maps,and the alignment of maps with respect to each other. Wepropose using Sparse Gaussian Processes for this purpose,and show that the representation has several advantages,including an intuitive alignment optimization, data com-pression, and sensor noise filtering. We demonstrate thesethree key capabilities on two real-world datasets.

  • Gunnelin, Åke
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Netzell, Olof
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics. National Board of Hoursing, Building and Planning.
    The relationship between property transaction prices, turnover rates and buyers' and sellers' reservation price distributionsManuscript (preprint) (Other academic)
    Abstract [en]

    This paper analyzes the relationship between movements in property transaction prices and movements in the underlying reservation price distributions of buyers and sellers and how these movements are linked to time varying turnover rate. A main conclusion in previous research is that transaction prices lag changes in buyers’ reservation price distribution and that an index tracking transaction prices is less volatile than an index tracking buyer reserves. We show that our less restrictive model of search and price formation reverses the volatility result in previous papers in realistic scenarios, i.e., transaction prices may be more volatile than underlying buyer reserves. We model transaction prices and turnover rates as functions of the moments of buyers’ and sellers’ reservation price distributions, the search intensity and the average bargaining power among buyers and sellers respectively. We derive the probability density function of transaction prices as a function of these parameters and hence a Maximum-likelihood estimator of the parameters, which serves as a new method of estimating indexes tracking movements in reservation price distributions from transaction data. We perform simulations where we show that the Maximum-likelihood estimator works as intended.

  • Lundgren, Elin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Evaluating resilience in the governing process of the food strategy for StockholmCounty: Resilience from theory to practice in a qualitativestudy2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To meet global challenges in food provision and to counteract environmental issues derivingfrom the food system, improved governance is necessary. Resilience is presented as a tool formanaging ecosystem services and for understanding what is required to achieve food security.In Sweden there is a national food strategy describing the continued development needed formeeting challenges in the food system. Several regional food strategies have been producedand an additional food strategy for Stockholm County is in the process of being developed byStockholm County Administrative Board. This food strategy could be of especial interest toevaluate due to Stockholm County being highly populated while having a low degree ofprimary food production. Assessing the governance system for the food strategy was ofinterests due to the large groups of stakeholders to consider in the process. The aim of thestudy was to add further knowledge on how resilience can be applied in practice by exploringthe extent of which the governance system for developing the food strategy promotesresilience. The research questions were formulated to investigate the governance system bymapping what stakeholders were involved in the process, what their responsibilities were andwhat relations existed between them. An additional research question was to test how thegovernance system promoted resilience by applying a set of principles for doing so.

    For collecting data, several stakeholders involved in developing the food strategy at the timeof the data collection were interviewed. Complementary data was also collected from journalarticles, books, documents provided by Stockholm County Administrative Board, websites,governmental publications and different kinds of reports. Quotes were selected to explain thefindings from the interviews, and a social network analysis was constructed to illustrate thestructure of the governance system. Another tool in the data analysis, which was also thepoint of the departure for constructing the research questions, was the resilience frameworkconsisting of a set of principles. Among these principles, five where applied for evaluating thegovernance system of the food strategy.

    The results were divided in two parts. The first section presents the results from performinginterviews by describing the governance system; identified stakeholders, their functions aswell as their relations. Two other themes identified from the interviews that were concludedto be important for the resulting governance system and also for the resilience evaluation were“collaboration” and “context”. Several stakeholders were identified, a few were concluded tobe more key than others as they belong to either the management group or the draftingcommittee. The stakeholders had national, regional and local responsibilities and were bothgovernmental and non-governmental organizations. The functions of the stakeholders werefor example to represent a certain part of the food system or contributing with national,regional or local knowledge about the food system. The relations among stakeholders in thegovernance system occurred between stakeholders working within the same geographicalscales and also between national, regional and local scales. In the center of the governancestructure were the management group that are to jointly decide on goals for the final strategydocument.

    The second part of the results constitutes the resilience evaluation, which was accomplishedby testing the results regarding the governance system (from part I) against the framework forresilience using the selected principles. These principles included maintain diversity andredundancy, manage connectivity, encourage learning, broaden participation and promotepolycentric governance. It was concluded that the governance system did follow all of theseprinciples in several aspects, but critical points were also identified. Among the positive 

    aspect were the positive attitude for learning among stakeholders in the governance system,the involvement of heterogenous groups interacting with one another and also themanagement group as a strong centre for decision-making. One of the main critical pointsidentified from performing the resilience evaluation suggests a few stakeholders to be lackingin the present governance system.

    The governance system for the food strategy had a large group of stakeholders, representingdifferent parts of the food system, including national/regional/local and governmental/nongovernmentalorganizations, interacting both within and across geographical scales. Theseaspects are important for promoting resilience according to the principles selected in thisstudy. By adding the suggested stakeholders, for example a few representatives from differentparts of the food system that was not involved in the process at the time of data collection, thegovernance system could promote resilience even more.

  • Public defence: 2019-04-26 10:00 F3, Stockholm
    Bessegato, Luca
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Modeling of Modular Multilevel Converters for Stability Analysis2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Modular multilevel converters (MMCs) have recently become the state-of-the-art solution for various grid-connected applications, such as high-voltage direct current (HVDC) systems and flexible alternating current transmission systems (FACTS). Modularity, scalability, low power losses, and low harmonic distortion are the outstanding properties that make MMCs a key technology for a sustainable future.


    The main objective of this thesis is the modeling of grid-connected MMCs for stability analysis. The stability of the interconnected system, formed by the converter and the ac grid, can be assessed by analyzing the converter ac-side admittance in relation to the grid impedance. Therefore, a method for the calculation of the ac-side admittance of MMCs is developed. This method overcomes the nonlinearities of the converter dynamics and it can be easily adapted to different applications. Moreover, the effects of different control schemes on the MMC ac-side admittance are studied, showing how the converter admittance can be reshaped. This is a useful tool for system design, because it shows how control parameters can be selected to avoid undesired grid-converter interactions.


    This thesis also studies ac/ac MMCs for railway power supplies, which are used in countries with a low-frequency railway grid, such as Germany (16.7 Hz) and Sweden (16 2/3 Hz). A hierarchical control scheme for these converters is devised and evaluated, considering the requirements and the operating conditions specific to this application. Furthermore, admittance models of the ac/ac MMC are developed, showing how the suggested hierarchical control scheme affects the three-phase and the single-phase side admittances of the converter. For computing the insertion indices, an open-loop scheme with sum capacitor voltage estimation is applied to the ac/ac MMC. Lyapunov stability theory is used to prove the asymptotic stability of the converter operated with the proposed control method. This specific open-loop scheme is also adapted to a modular multilevel matrix converter, which performs three-to-three phase direct conversion.


    Finally, this thesis presents the design of a down-scaled MMC prototype for experimental verification, rated at 10 kW with 30 full-bridge submodules. The hardware and the software are designed to be easily reconfigurable, which makes the converter suitable for different research projects focused on MMCs. Experiments on this down-scaled MMC are used to support and validate the key results presented throughout the thesis.

  • Bijman, Nicolaas Peter
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Exploring affordances of tangible user interfaces for interactive lighting2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper explores interaction with lighting through a tangible user interface (TUI). In a TUI the physical object and space around it are part of the interface. A subset of tangible interaction called spatial interaction is the main focus of this paper. Spatial interaction refers to translation, rotation or location of objects or people within a space. The aim of this paper is to explore the relation between spatial inputs and lighting outputs based on different design properties.

    A user test is set up to explore the effect that design properties of a TUI have on the lighting output that participants map to spatial inputs. The results of the conducted user test indicate that communicating affordances to the user is an important factor when designing couplings between spatial inputs and lighting outputs. The results further show that the shape of the interface plays a central role in communicating those affordances and that the overlap of input and output space of the interface improves the clarity of the coupling.

  • Liljeqvist, Marcus Elwar
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Gaming for Good: Triggering do-good Excitement in a Mobile Game2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mobile games present a great opportunity for organizations with sustainability agendas to spread their message and generate revenue towards its cause, as they are the best money generating apps. This can be done through designing so-called persuasive games. A major challenge when designing such a game is that the sustainability agenda might compromise the gaming experience, rendering an uninteresting game. The present research explores what could trigger both an interesting game that also compromises a do-good agenda by designing and play testing two versions of a persuasive game called Aqua Escape. Results indicated that users felt more excited about the game once they knew about the social agenda. They also wanted more information on the social agenda integrated into the app than was already there.

  • Yuan, Luyao
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Sustainability Aspects of ICT in Agriculture and Food Systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis project aims to explore ICT solutions in agriculture and food systems, and to analyze their sustainability aspects. As a result, a comprehensive picture of existing and coming ICT solutions along the food chain is presented based on extensive literature review. Their enabled impacts are qualitatively analyzed for selected aspects of food security and environmental sustainability. Moreover, a few of ICT enabled solutions’ GHG emissions reduction potentials in agricultural and land use sector in the year 2030 are estimated quantitatively, ranging from 9 Mt to 31 Mt, depending on assumptions (6 to 50 Mt after sensitivity analysis). These results, which cannot be seen as a representation of the overall ICT potential to enable emission reductions in agriculture and the food chain, are discussed in light of earlier suggested overall ICT potentials in this area. Moreover, limitations and uncertainties of the study are further clarified. Overall, the qualitative analysis identifies a high number of solutions for ICT in the agriculture and food systems with an assumed potential to promote sustainable development. However, due to the lack of published quality data for these solutions, the predicted sustainability potential cannot be accurately estimated. 

  • Alvarez Custodio, Maria
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Autonomous Recharging System for Drones: Detection and Landing on the Charging Platform2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the last years, the use of indoor drones has increased significantly in many different areas. However, one of the main limitations of the potential of these drones is the battery life. This is due to the fact that the battery size has to be limited since the drones have a maximum payload in order to be able to take-off and maintain the flight. Therefore, a recharging process need to be performed frequently, involving human intervention and thus limiting the drones applications.

    In order to solve this problem, this master thesis presents an autonomous recharging system for a nano drone, the Crazyflie 2.0 by Bitcraze AB. By automating the battery recharging process no human intervention will be needed, and thus overall mission time of the drone can be considerably increased, broadening the possible applications.

    The main goal of this thesis is the design and implementation of a control system for the indoor nano drone, in order to control it towards a landing platform and accurately land on it. The design and implementation of an actual recharging system is carried out too, so that in the end a complete full autonomous system exists.

    Before this controller and system are designed and presented, a research study is first carried out to obtain a background and analyze existing solutions for the autonomous landing problem.

    A camera is integrated together with the Crazyflie 2.0 to detect the landing station and control the drone with respect to this station position. A visual system is designed and implemented for detecting the landing station. For this purpose, a marker from the ArUco library is used to identify the station and estimate the distance to the marker and the camera orientation with respect to it.

    Finally, some tests are carried out to evaluate the system. The flight time obtained is 4.6 minutes and the landing performance (the rate of correct landings) is 80%.

  • Harren, Maja
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Application of Circular Economy to SME Batik Dyeing and Finishing: Sustainability Vetting of Ciwaringin Batik2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study is part of a feasibility study conducted by the Sustainability and Resilience Company (su-re.co), and is identified within this report as the sustainability vetting. This study aims to evaluate the sustainability of the natural indigo-dyeing process at a small medium enterprise (SME) batik dying community, Ciwaringin Batik, located in Cirebon, West Java, Indonesia. Following this, sustainable development strategies (SDS) based on the Circular Economy (CE) RESOLVE Framework will be created for Ciwaringin Batik to further empower the community and provide sustainable business growth initiatives. An iterative qualitative and quantitative data methodology is used when collecting and analyzing production data from Ciwaringin Batik. Data is collected from 9 Ciwaringin Batik craftsmen, who use natural indigo dye during batik production, in Life Cycle Inventory (LCI) format, questionnaires, and through a site-visit to Ciwaringin Batik. Water and indigo consumption data was thoroughly analyzed as it is directly related to a feasibility study conducted by su-re.co and is relevant to their future involvement with Ciwaringin. Current sustainable and “unsustainable” production practices were identified, 10 SDS’s were created following the RESOLVE framework structure, 6 SDS’s were explained and then prioritized regarding implementation feasibility.

  • Public defence: 2019-04-26 10:00 Kollegiesalen, Stockholm
    Zandi Shafagh, Reza
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Thiol-ene Nanostructuring2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improving the health and well-being of humankind does not only constitute

    part of our moral codes, but is also enlisted as the number three goal of

    the 2030 agenda for sustainable development set by the UN. Fulfilling such

    objective in the regions of resource-poor settings or for age groups with more

    vulnerability to infectious agents demands immediate actions. This has necessitated

    novel ways of rapid and ultra-sensitive diagnostics to provide compact

    and affordable systems, e.g. for an early detection of bacteria and viruses.

    The fields of bio-micro/nanoelectromechanical systems (BioMEMS/NEMS)

    and lab-on-a-chip (LoC) have been founded based on such demands, but

    critically challenged by problems partly associated with manufacturing and

    material domains and biosensing methods. The fabrication methods for the

    miniaturization of features and components are often complicated and expensive,

    the commonly used materials are typically not adaptable to industrial

    settings, and the sensing mechanisms are sometimes not sensitive enough for

    the detection of lowly-concentrated samples.

    In this thesis, new methods of ultra-miniaturization, as well as conventional

    cleanroom-based techniques, for nanopatterning of well-defined topographies

    in off-stoichiometry thiol-ene-(epoxy) polymers are presented. In addition,

    their use for several sensing applications has been demonstrated. The

    first part of the thesis gives an introduction to the field of BioMEMS/NEMS.

    The second part of the thesis presents a technical background about the

    prevalent methods of polymer micro- and nanofabrication, implementation

    of the resulting polymer structures for different sensing applications, along

    with the existing challenges and shortcomings associated with state of the

    art. The third part of the thesis presents e-beam nanostructuring of thiol-ene

    resist, for the first time, achieving the smallest and densest features reported

    in these polymer networks. The thiol-ene-based polymer also represents a

    novel class of e-beam resist resulting in structures with reactive surface nature.

    The fourth part of the thesis demonstrates the use of thiol-ene-epoxy

    systems for nanoimprint lithography and further shows the structuring of

    high-aspect-ratio and hierarchical topologies via single-step UV-NIL. The fifth

    part of the thesis introduces Micro- and NanoRIM platforms for scalable and

    off-cleanroom manufacturing of microfluidic devices and nanostructuring of

    materials in thiol-ene (-epoxy) systems. The sixth part of the thesis exhibits

    the implementation of the noted nanofabrication methods for different

    BioMEMS/NEMS applications including protein nanopatterning, simultaneous

    molding and surface energy patterning, ultra-sensitive digital biosensing,

    and facile quartz crystal microbalance (QCM) sensor packaging.

  • Public defence: 2019-04-26 18:22 FA32, Stockholm
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Super resolution fluorescence imaging: analyses, simulations and applications2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fluorescence methods offer extraordinary sensitivity and specificity, and are extensively used in the life sciences. In recent years, super resolution fluorescence imaging techniques have developed strongly, uniquely combining ~10 nm sub diffraction resolution and specific labeling with high efficiency. This thesis explores this potential, with a major focus on Stimulated Emission Depletion, STED, microscopy, applications thereof, image analyses and simulation studies. An additional theme in this thesis is development and use of single molecule fluorescence correlation spectroscopy, FCS, and related techniques, as tools to study dynamic processes at the molecular level. In paper I the proteins cytochrome-bo3 and ATP-synthase are studied with fluorescence cross-correlation spectroscopy, FCCS. These two proteins are a part of the energy conversion process in E. coli, converting ADP into ATP. We found that an increased interaction between these proteins, detected by FCCS, correlates with an increase in the ATP production. In paper II an FCS-based imaging method is developed, capable to determine absolute sizes of objects, smaller than the resolution limit of the microscope used. Combined with STED, this may open for studies of membrane nano-domains, such as those investigated by simulations in paper VII. In paper III and paper IV super resolution STED imaging was applied on Streptococcus Pneumoniae, revealing information about function and distribution of proteins involved in the defense mechanism of the bacteria, as well as their role in bacterial meningitis. In paper V, we used STED imaging to investigate protein distributions in platelets. We then found that the adhesion protein P-selectin changes its distribution pattern in platelets incubated with tumor cells, and with machine learning algorithms and classical image analysis of the STED images it is possible to automatically distinguish such platelets from platelets activated by other means. This could provide a strategy for minimally invasive diagnostics of early cancer development, and deeper understanding of the role of platelets in cancer development. Finally, this thesis presents Monte-Carlo simulations of biological processes and their monitoring by FCS. In paper VI, a combination of FCCS and simulations was applied to resolve the interactions between a transcription factor (p53) and an oncoprotein (MDM2) inside live cells. In paper VII, the feasibility of FCS techniques for studying nano-domains in membranes is investigated purely by simulations, identifying the conditions under which such nano-domains would be possible to detect by FCS. In paper VIII, proton exchange dynamics at biological membranes were simulated in a model, verifying experimental FCS data and identifying fundamental mechanisms by which membranes mediate proton exchange on a local (~10nm) scale.

  • Bafounis Kottas, Emmanouil
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Implementation and integration of a collaborative robot in a production line2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Scope of this thesis is the integration and implementation of a collaborative robot in the production line. In the first chapter, the project is described, and its objectives, purpose, boundaries and requirements are defined. Moreover, the project management tools and techniques are presented. All the steps and procedures followed before the initiation of the project are analysed. In the second chapter, the basic theoretical background necessary for a better understanding of the content of this thesis is presented. The history and development of collaborative robots, as well as the industrial evolutions are mentioned. The different types of collaborative robots and their importance in Industry 4.0 and current production are analysed. The third chapter deals with the detailed description of the project. All the devices and equipment are presented thoroughly. The programming logic and working flow is explained. In the last chapter according to the initial objectives, boundaries and requirements the success of the project is assessed. An analysis of how the installation of automate corrugate loader affected the production process is performed. Future changes, improvements and technical suggestions are discussed. The ultimate goal of this thesis project is that the content in the thesis report will be used as a guide for future installations of same or similar type of robots. The aim is to avoid many of the mistakes made, due to rush decisions, lack of experience and communication between team members. The leaning curve obtained during the implementation of the project, can lead to more effective projects in the future.

  • Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Xu, Lei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Miao, Xinyan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Li, Nailin
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Öktem, Ozan
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Franzén, Bo
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Auer, Gert
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Lomnytska, Marta
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Super-resolution microscopy can identify specific protein distribution patterns in platelets incubated with cancer cellsManuscript (preprint) (Other academic)
    Abstract [en]

    Protein contents in platelets are frequently changed upon tumor development and metastasis. However, how cancer cells can influence protein-selective redistribution and release within platelets, thereby promoting tumor development, remains largely elusive. With fluorescence-based super-resolution stimulated emission depletion (STED) imaging we reveal how specific proteins, implicated in tumor progression and metastasis, re-distribute within platelets, when subject to soluble activators (thrombin, adenosine-diphosphate and thromboxaneA2), and when incubated with cancer (MCF-7, MDA-MB-231, EFO21) or non-cancer cells (184A1, MCF10A). Upon cancer cell incubation, the cell-adhesion protein P-selectin was found to re-distribute into circular nano-structures, consistent with accumulation into the membrane of protein-storing alpha-granules within the platelets. These changes were to a significantly lesser extent, if at all, found in platelets incubated with normal cells, or in platelets subject to soluble platelet activators. From these patterns, we developed a classification procedure, whereby platelets exposed to cancer cells, to non-cancer cells, soluble activators as well as non-activated platelets all could be identified in an automatic, objective manner. We demonstrate that STED imaging, in contrast to electron and confocal microscopy, has the necessary spatial resolution and labelling efficiency to identify protein distribution patterns in platelets and can resolve how they specifically change upon different activations. Combined with image analyses of specific protein distribution patterns within the platelets, STED imaging can thus have a role in future platelet-based cancer diagnostics and therapeutic monitoring. The presented approach can also bring further clarity into fundamental mechanisms for cancer cell-platelet interactions, and into non-contact cell-to-cell interactions in general.