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  • Li, Yi
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Single Equipment Visualization for Improved Power System Monitoring2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the expansion of the power system scale, the demand for power system visualization is increasing in the recent of years. A stable operation of the power system is very important for people’s normal life. Operators have to monitor 4-5 screens at the same time to check the status of the system. Each screen contains thousands of transmission lines and thousands of different data. When one of the data is out of the safe range, the operator needs to take action and repair it in time. Otherwise, it will lead to a catastrophe.

    The goal of this thesis is to test whether the graphics visualization can be used in the power system and accurately communicate the data. A new visualization was created which included graphics to express data in the single transmission line diagram. Afterwards, a user study was conducted with 7 people, where the results showed that some data could be expressed in the image but not all of them. And the feature of image visualization was that it contained more useful information that could be easily understood by the operators.

  • Häkkä, Max
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Designing a Persuasive Mobile Application for Sharing Food Between Students and Restaurants2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Food waste is a monumental problem as food production accounts for nearly a third of greenhouse gas emissions globally and nearly a third of it ends up as waste. By changing people’s behaviors and attitudes, this surplus food could be eaten instead. Persuasive technologies can be an effective way of changing people’s behaviors; however, they may narrow down the view of sustainability if applied in a manner that focuses too much on individuals (among other things). In this thesis project the focus has been on how to best design a persuasive application that reduces food waste by considering the needs of both restaurants and consumers.

    Two versions of an application were created based on interviews with students and restaurants, where one of the applications included features based on Persuasive Systems Design (PSD). A user study was then conducted, where the users received a number of tasks to complete and answered a questionnaire on the PSD features afterwards. The results showed that both of the applications had a similar number of errors from the users during the tasks. Besides this, all of the four features based on PSD were rated positively by users, with all features having a mean rating of 0.83 or higher on a 7-point Likert scale

  • Cournut, Pierre
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Identification model of musical works using record linkage2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis is based on a project that is part of IBM’s collaboration with a Collecting Right Organization that collects and distributes payments of authors’ rights. The project aimed at helping this organization identify right beneficiaries for musical tracks listened on online streaming platforms. Given as an input a list of tracks composed of metadata such as artist names, titles and listening statistics, the goal was to match each line with its corresponding element in this organization’s documentation. Since each broadcaster has its own catalogue of music, it can be hard sometimes to find the correct matching for each song. In practice, this organization has a dedicated team that handles manually some of the non-trivial cases. Whereas their identification process focuses on resources that contribute to 90% of the revenue of each listening report, it achieves an identification rate of around 70% of the resources declared which represent a substantial amount of unprocessed tracks left aside.

    In this thesis, we investigate the possibility to outperform the current solution and design a new identification model that combines concepts and technologies from various fields including search engines, string metrics and machine learning. First, the identification process used by the organization was reproduced and refined to quickly process the most trivial cases. On top of this, an identification algorithm that relies on a machine learning framework was built to process non-trivial cases. This method showed very promising results since it achieves an identification rate and a false discovery rate of the order of those of the current solution without the use of a dedicated team of experts.

  • Bäckström, Anton
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Breaking and fixing the Zero-knowledge password policy checks protocol by Kiefer and Manulis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Zero-knowledge password policy checks (ZKPPC) were introduced in Kiefer and Manulis’ report from 2014. The protocol aimed to solve the longstanding issue with servers requiring clients to provide their password in plain text to ensure its strength. Their protocol was intended to eliminate the need for users to trust the server to store and handle passwords correctly while simultaneously allowing the server to know that the registered password was strong enough. This thesis has investigated the soundness of the protocol by Kiefer and Manulis and will present three new zero-day vulnerabilities discovered in the process. The vulnerabilities allow a dishonest user to prove adherence to the policy for invalid passwords. Additionally, the thesis presents our new Proof of Inequality which prevents one of these vulnerabilities, as well as an extension for an incomplete part of the protocol. The two remaining zero-day vulnerabilities are weaknesses in the protocol left for future research.

  • Marinone, Emilio
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Evaluation of New Features for Extractive Summarization of Meeting Transcripts: Improvement of meeting summarization based on functional segmentation, introducing topic model, named entities and domain specific frequency measure2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Automatic summarization of meeting transcripts has been widely stud­ied in last two decades, achieving continuous improvements in terms of the standard summarization metric (ROUGE). A user study has shown that people noticeably prefer abstractive summarization rather than the extractive approach. However, a fluent and informative ab­stract depends heavily on the performance of the Information Extrac­tion method(s) applied.

    In this work, basic concepts useful for understanding meeting sum­marization methods like Parts-of-Speech (POS), Named Entity Recog­nition (NER), frequency and similarity measure and topic models are introduced together with a broad literature analysis. The proposed method takes inspiration from the current unsupervised extractive state of the art and introduces new features that improve the baseline. It is based on functional segmentation, meaning that it first aims to divide the preprocessed source transcript into monologues and dialogues. Then, two different approaches are used to extract the most impor­tant sentences from each segment, whose concatenation together with redundancy reduction creates the final summary.

    Results show that a topic model trained on an extended corpus, some variations in the proposed parameters and the consideration of word tags improve the performance in terms of ROUGE Precision, Re­call and F-measure. It outperforms the currently best performing un­supervised extractive summarization method in terms of ROUGE-1 Precision and F-measure.

    A subjective evaluation of the generated summaries demonstrates that the current unsupervised framework is not yet accurate enough for commercial use, but the new introduced features can help super­vised methods to achieve acceptable performance. A much larger, non-artificially constructed meeting dataset with reference summaries is also needed for training supervised methods as well as a more accu­rate algorithm evaluation.

    The source code is available on GitHub: https://github.com/marinone94/ThesisMeetingSummarization

  • Cöster, Jonatan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    The effects of shadows on depth perception in augmented reality on a mobile device2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the visual perception of depth in computer graphics, people rely on a number of cues, including depth of field, relative size of objects in perspective, and shadows. This work focuses on shadows in Augmented Reality. An experiment was performed in order to measure the effects of having virtual objects cast shadows on real objects. Users performed the task of placing a virtual object on a physical table, in an Augmented Reality environment displayed on a mobile device. The virtual object was either a cube or a sphere. The effects of having shadows enabled was measured by time to task completion and the positional error. Qualitative measurements of the user experience were also made, through the use of questionnaires. The results showed a decrease in both positional error and time to task completion when shadows were enabled. The results also indicated that users placed the objects with a higher degree of certainty when shadows were enabled. The quantitative and qualitative results of the experiment showed that users found it easier to perceive the position of the virtual object with respect to the physical object when the virtual object cast shadows.

  • Rastogi, Tanay
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Load Identification from Aggregated Data using Generative Modeling2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the view of an exponential increase in demand for energy, there is a need to come up with a sustainable energy consumption system in residential buildings. Several pieces of research show that this can be achieved by providing real-time energy consumption feedback of each appliance to its residents. This can be achieved through Non-Intrusive Load Monitoring System (NILM) that disaggregates the electricity consumption of individual appliances from the total energy consumption of a household. The state-of-art NILM have several challenges that preventing its large-scale implementation due to its limited applicability and scalability on different households. Most of the NILM research only trains the inference model for a specific house with a limited set of appliances and does not create models that can generalize appliances that are not present in the dataset. In this Master thesis, a novel approach is proposed to tackle the above-mentioned issue in the NILM. The thesis propose to use a Gaussian Mixture Model (GMM) procedure to create a generalizable electrical signature model for each appliance type by training over labelled data from different appliances of the same type and create various combinations of appliances by merging the generated models. Maximum likelihood estimation method is used to label the unlabeled aggregated data and disaggregate it into individual appliances. As a proof of concept, the proposed algorithm is evaluated on two datasets, Toy dataset and ACSF2 dataset, and is compared with a modified version of state-of-the-art RNN network on ACS-F2 dataset. For evaluation, Precision, Recall and F-score metrics are used on all the implementations. From the evaluation, it can be stated that the GMM procedure can create a generalizable appliance signature model, can disaggregate the aggregated data and label previously unseen appliances. The thesis work also shows that given a small set of training data, the proposed algorithm performs better than RNN implementation. On the other hand, the proposed algorithm highly depends on the quality of the data. The algorithm also fails to create an accurate model for appliances due to the poor initialization of parameters for the GMM. In addition, the proposed algorithm suffers from the same inaccuracies as the state of art.

  • Rodés-Guirao, Lucas
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Deep Learning for Digital Typhoon: Exploring a typhoon satellite image dataset using deep learning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Efficient early warning systems can help in the management of natural disaster events, by allowing for adequate evacuations and resources administration. Several approaches have been used to implement proper early warning systems, such as simulations or statistical models, which rely on the collection of meteorological data. Data-driven techniques have been proven to be effective to build statistical models, being able to generalise to unseen data. Motivated by this, in this work, we explore deep learning techniques applied to the typhoon meteorological satellite image dataset "Digital Typhoon". 

    We focus on intensity measurement and categorisation of different natural phenomena.

    Firstly, we build a classifier to differentiate natural tropical cyclones and extratropical cyclones and, secondly, we implement a regression model to estimate the centre pressure value of a typhoon. In addition, we also explore cleaning methodologies to ensure that the data used is reliable.

    The results obtained show that deep learning techniques can be effective under certain circumstances, providing reliable classification and regression models and feature extractors. More research to draw more conclusions and validate the obtained results is expected in the future.

  • Disputas: 2019-05-17 10:00 Air & Fire auditorium, Science for Life Laboratory, Solna
    Cengic, Ivana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Systembiologi.
    Synthetic biology approaches for improving production of fatty acid-derived compounds in cyanobacteria2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The environmental consequences associated with the use of fossil-sourced fuels and chemicals have brought with it a realization that future development must move in a more sustainable direction. Currently available biofuels or renewably produced chemical, such as bioethanol or biodiesel, are produced from microbial fermentation of sugar-rich crops or by chemical conversion of natural oils or fats. However, these strategies are not sustainable in the long run as fuel and chemical production competes with food supply and arable land usage. Instead of relying on photosynthetic feedstocks that require further conversion, one can engineer photosynthetic cyanobacteria to produce a product of interest directly from CO2 and sunlight. The first part of this thesis aimed to develop new synthetic biology tools for the model cyanobacteria Synechocystis sp. PCC 6803. The second part of the thesis focused on evaluating the regulation of fatty acid synthesis in cyanobacteria, and the production of fatty acid-derived chemicals in Synechocystis.

    In paper I, fusion of small affinity proteins (Affibodies) to the major type IV pili protein was shown to mediate successful surface display of the affibody. This surface display strategy was further shown to allow inter-species binding between Synechocystis and Escherichia coli or Staphylococcus carnosus displaying complementary polymerizing affibodies.

    In paper II, a CRISPR-interference tool was successfully implemented in Synechocystis for inducible gene repression. Further, its multiplexing ability was proven by simultaneous repression of up to four aldehyde reductase/dehydrogenase genes. In paper III, this established CRISPRi tool was used to target and repress native pathways competing with heterologous fatty alcohol production in Synechocystis. Repressing the gene encoding the PlsX phosphate acyltransferase allowed re-direction of carbon-flux from membrane lipids to fatty alcohol production, with a final best strain producing 10.4 mg g-1 DCW octadecanol and hexadecanol.

    In paper IV, the transcriptional response towards perturbations within the fatty acid synthesis pathway was evaluated for the two model cyanobacteria Synechocystis and Synechococcus elongatus PCC 7942. Preliminary results indicate that blocking fatty acid synthesis initiation/elongation causes a transcriptional response of the involved pathway genes only in S. elongatus PCC 7942, indicating differential transcriptional responses in these two strains.

    In paper V, metagenomically sourced aldehyde deformylating oxygenase (Ado) variants were evaluated for their alka(e)ne synthesizing ability. Several of these novel Ado enzymes outperformed the generally well-performing Ado from S. elongatus when relating alka(e)ne production to the soluble enzyme amount.

  • Kawahara, Alberto
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Improving Residential In-building Energy Performance for Multi-operator and Multi-standard Radio Access in Distributed Antenna Systems (DAS)2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Good signal in indoor environments has always been one of the mobile operator’s main challenges. The situation gets even more complex when dealing with new energy-efficient buildings that insulate the heat inside the building but at the same time causes higher losses from the macro base stations. In this scenario, indoor solutions are required to overcome this problem. Nowadays, there are two main indoor solutions: Distributed Antenna Systems (DAS) and small cells.

    This thesis focuses on DAS solutions and investigates the power consumption difference between the two main architectures: Passive and Active/Hybrid DAS. The evaluation is made by measuring the power consumption of the active components and adding them to the already existing Base Station power consumptions models. Power consumption measurements were performed for four commercial bands: 900, 1800, 2100, 2600 MHz. Power consumption and system capacity trade-off between the passive and active DAS solutions is also presented. The capacity analysis is focused on LTE and applied to a real case study: Norra Tornen residential building. Final results show that up to 75% of the indoor power consumption can be saved when implementing an active DAS solution without affecting the service quality.

  • Gonzalo Peces, Carlos
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Energy-Efficient Communication with Lightweight M2M in IoT Networks2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    OMA’s Lightweight Machine to Machine (LwM2M) is an application protocol for device management in the Internet of Things (IoT) that has been recently published and widely adopted in a lot of projects. The protocol is designed to operate in sensor networks and machine-to-machine environments, where one of the main constraints is the energy consumption since the nodes are usually battery powered. Different strategies to achieve high energy efficiency in IoT networks have been developed, but there is no deep knowledge about the performance of LwM2M operating with them. Moreover, the specification of this protocol includes one strategy, called the Queue Mode, which could be more efficient than the usual ones because it has been specified for this particular protocol.

    This project aims to implement this Queue Mode at both sides of the communication, and then evaluate its performance by comparing it with TSCH, which is the standard MAC protocol used in IEEE 802.15.4 that defines a way of radio duty cycling. It has been proven to achieve a high energy efficiency, and that is the main reason why it is selected. The comparison is performed according to several metrics to have a comprehensive evaluation, and in different kind of scenarios, with different numbers of IoT devices and different parameters in the communication.

    The implementation was done inside the Contiki-NG OS for the client side, which is an operating systems designed for constrained devices. For the server side it has been carried out inside the Eclipse Leshan code, which is a LwM2M implementation in Java made by the Eclipse Foundation. As a result of the evaluation, it shown that both implementations operate correctly.

    This thesis contributes as a guideline for making decisions about which low power strategy is better to use depending on the IoT scenario and the type of application. It shows that for many use cases Queue Mode is a better option than TSCH because it achieves a higher energy efficiency and the rest of the metrics used in the evaluation have also improved values. TSCH has a better performance only in demanding scenarios or in cases where the communication is not produced at fixed time instants.

    The thesis was developed in cooperation with RISE SICS AB, Networked Embedded Systems Group.

  • Schickhofer, Lukas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Mekanik, Biomekanik.
    Malinen, Jarmo
    Aalto University.
    Mihaescu, Mihai
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Compressible flow simulations of voiced speech using rigid vocal tract geometries acquired by MRI2019Inngår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 145, nr 4, s. 2049-2061, artikkel-id 0001-4966/2019/145(4)/2049/13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Voiced speech consists mainly of the source signal that is frequency weighted by the acoustic filtering of the upper airways and vortex-induced sound through perturbation in the flow field. This study investigates the flow instabilities leading to vortex shedding and the importance of coherent structures in the supraglottal region downstream of the vocal folds for the far-field sound signal. Large eddy simulations of the compressible airflow through the glottal constriction are performed in realistic geometries obtained from three-dimensional magnetic resonance imaging data. Intermittent flow separation through the glottis is shown to introduce unsteady surface pressure through impingement of vortices. Additionally, dominant flow instabilities develop in the shear layer associated with the glottal jet. The aerodynamic perturbations in the near field and the acoustic signal in the far field are examined by means of spatial and temporal Fourier analysis. Furthermore, the acoustic sources due to the unsteady supraglottal flow are identified with the aid of surface spectra, and critical regions of amplification of the dominant frequencies of the investigated vowel geometries are identified.

  • Disputas: 2019-05-10 09:00 Kollegiesalen, Stockholm
    Locke, Ryan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    City Re-Making Approaches in Contemporary Urbanism: “Re-Urbanism” as a Strategy for the Revitalization of Detroit and Declining Cities2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Many cities today are experiencing extreme widespread urban decline, at a time when urban growth and revitalization are prioritized on the agenda. This dissertation examines a number of prominent urban revitalization strategies for declining cities, specifically highlighting the emblematic case of Detroit as a research subject. That city offers many lessons as the epitome of both urban decline and urban revitalization, as evidenced through the media narratives surrounding the “rebirth of Detroit” and its positive improvements over recent years. Through this and other case studies, the dissertation investigates different approaches in the leading contemporary paradigms of urbanism, including the role of place-based and heritage-based strategies for the declining city, and their different structural approaches. These include differences sought in both city structure, and in the collaborative structure of revitalizing institutions. From there, the dissertation draws key lessons together into a synthesis approach called “Re-Urbanism” – an advancement of a model originally developed by Robert Fishman. The model describes strategic partnerships between local government entities, private business leaders, private charitable foundations, small scale grass roots activism, and local entrepreneurship, all aimed at making place-based, heritage-based structural reconnections within the city itself. The dissertation concludes with specific policy and practice recommendations, as well as ideas for further research.

  • Disputas: 2019-05-24 10:15 F3, Stockholm
    Winroth, Marcus
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Dynamics of Exhaust Valve Flows and Confined Bluff Body Vortex Shedding2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis can be divided into two interconnected topics; engine exhaust-valve flows and confined bluff-body vortex shedding. When optimising engine flow systems it is common to use low order simulation tools that require empirical inputs, for instance with respect to flow losses across the exhaust valves. These are typically obtained from experiments at low pressure ratios and for steady flow, assuming the flow to be insensitive to the pressure ratio and that it can be considered as quasi-steady. Here these two assumptions are challenged by comparing measurements of mass-flow rates under steady and dynamic conditions at realistic pressure ratios. The experiments with a static valve were carried out using a high-pressure flow bench at cylinder pressures up to 500 kPa. For the dynamic-valve experiments the transient flow rate during the blowdown phase of an initially pressurised cylinder was determined. Here a linear motor actuated the valve to obtain equivalent engine speeds in the range 800–1350 rpm. It was shown that neither of the above mentioned assumptions are valid and a new non-dimensional quantification of the steadiness of the process was formulated. Furthermore it was shown through Schlieren visualisation that the shock structures in the exhaust port differ depending on if the system dynamics are included or not. The study shows that reliable results of flow losses past exhaust valves can only be obtained in dynamic experiments at representative pressure ratios. The second topic arose from the need to monitor time-resolved mass-flow rates in conduits. A mass-flow meter based on vortex shedding from bluff bodies was designed where microphones are used to detect the shedding frequency. It consists of a forebody and a downstream mounted tail and the system was shown to be capable of measuring pulsating flow rates. Furthermore, the flow topology associated with different forebody and splitter plates has been characterised, through visualisation of the flow behind the shedder and on the splitter plate. It has been shown that for long splitter plates a “horse shoe” like vortex, which attaches to the tail, is formed. It has also been shown that another energetic mode (denoted mode-II) can interact with and disrupt the primary vortex formation. A hypothesis for the appearance of mode-II has been formulated, linking it to the periodic separation of the boundary layer at the conduit wall.

  • Nyström, Andreas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur.
    Ockuperbara rum2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    En plats för sociala, kulturella och politiska möten

    Hur kan arkitektur stödja processer så att möten med det tidigare okända skall kunna uppstå?

    I mitt arbete har jag avsett att forma en plats där olika grupper av människor skall kunna komma i kontakt med varandra.

    Platsen jag valt är Nytorps Gärde. Ett stort parkliknande område 15 minuter söder om Stockholms innerstad. Platsen ligger mellan områdena Björkhagen och Kärrtorp.

    Avsikten med mitt arkitektoniska förslag är inte att förhålla mig till en viss målgrupp eller typ av aktivitet utan att istället erbjuda en plats vilken så många som möjligt skall känna sig välkomna att tillfälligt ockupera för sina ändamål. Det oavsett om dessa utgörs av politiska möten, kulturella happenings eller t.ex. religiösa ceremonier.

    Detta betyder dock inte att jag därmed menar att mitt projekt skulle kunna passa för alla typer av sysslor eller skulle behöva vara generellt, opersonligt och föränderligt. Bara det att jag har för avsikt och målsättning med projektets program, eller delvis frånvaro av det samma, att det inte skall verka exkluderande vad det gäller politisk, kulturell eller annan tillhörighet.

  • Disputas: 2019-05-28 15:00 Conference room, Madrid
    Ploussard, Quentin
    KTH, Skolan för elektroteknik och datavetenskap (EECS). Research Technology Institute, Comillas Pontifical University, Spain; Delft University of Technology, the Netherlands.
    Efficient reduction techniques for a large-scale Transmission Expansion Planning problem2019Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The aim of Transmission Expansion Planning (TEP) studies is to decide which, where, and when new grid elements should be built in order to minimize the total system cost. The lumpiness of the investment decisions, together with the large size of the problem, make the problem very hard to solve. Consequently, methods should be put in place to reduce the size of the problem while providing a similar solution to the one that would be obtained considering the full size problem. Techniques to model the TEP problem in a compact way, also called reduction methods, can reduce the size of the TEP problem and make it tractable. This thesis provides new techniques to reduce the size of the TEP problem in its main three dimensions: the representation made of the grid (spatial dimension), the representation made of the relevant operation situations (temporal representation), and the number of candidate grid elements to consider. In each of the three reduction techniques proposed in this thesis work, the first step consists in solving a linear relaxation of the TEP problem. Then, they make use of information that is relevant to make the network investment decisions to formulate the TEP problem in a compact way for a certain dimension. I use the potential benefits brought by candidate lines to reduce the size of the representation made of the temporal variability in the problem. Besides, I reduce the size of the network by preserving the representation made of the congested lines and partially installed lines while computing an equivalent for other network elements. Lastly, I manage to reduce the set of candidate lines to consider based on the set of expanded corridors and the amount of new capacity built in them. I also compare each of the reduction techniques that I have developed to alternative reduction methods discussed in the literature within various case studies. In each of the three reduction methods proposed, the TEP solution computed solving the TEP problem resulting from applying the proposed reduction methods is more accurate (efficient) than the ones computed applying alternative reduction methods. Besides, this solution is almost as efficient as the solution of the original TEP problem, i.e. the TEP problem that has not been reduced by the proposed reduction method. As a next step, one may explore combining the three reduction methods proposed to maximize the reduction achieved in the size of the TEP problem.

  • Disputas: 2019-05-16 10:00 Sal F3, Stockholm
    Anton, Nicholas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Förbränningsmotorteknik.
    Engine Optimized Turbine Design2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Produkt- och tjänstedesign.
    Verifiering av accelerometer mätning i 16-bitars mikrokontroller2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Denna rapport är ett examensarbete vid institutionen för mekatronik vid KTH. I arbetet jämförs två metoder för utveckling och verifiering av en algoritm för accelerationsanalys i en mikrokontroller (sedarmera förkortat µC). En µC av typ MSP430G2553 används som målsystem. Målet med algoritmen är att µCn skall kunna särskilja rekylacceleration från andra accelerationer som slag och mekanismrörelse i ett vapen. I arbetet presenteras två metoder för utveckling och verifiering. Alternativ 1 använder endast målsystemet och dess mjukvaruverktyg. Alternativ 2 använder målsystem och mjukvaruverktyg men också ett kombinationsinstrument med både oscilloskop-funktion och arbiträr-vågforms-generator. I rapporten undersöks också två olika accelerometrar samt två varianter av µC. Med hjälp av kombinationsinstrument kunde flertalet referensmätningar genomföras av vapnets acceleration vid rekyl. Kombinationsinstrumentet användes också för att simulera accelerationer mot målsystemet. Resultatet av arbetet är att verifiering och utveckling med kombinationsinstrument (alternativ 2) är fördelaktigt ur flera synpunkter. Men att alternativ 1 också besitter flera fördelar. Den främsta fördelen med alternativ 2 är att accelerationsdatat enkelt kunnat samlats in utan beroenden av µCs prestanda eller programmeringsfel. Instrumentet underlättar flera andra delar i utveckling som extern verifiering av programmets exekvering och möjligheten att reproducera tidigare samlad accelerationsdata mot målsystem. Vilket gör kombinationsinstrumentet till ett behändigt utvecklingssystem.

  • Disputas: 2019-05-22 10:00 643, Stockholm
    Darwish, Rami
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Industriell Management.
    The Missing link: Business Models Lock-in in Sociotechnical Transitions2019Licentiatavhandling, monografi (Annet vitenskapelig)
    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.

  • Pernestål Brenden, Anna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Centra, Integrated Transport Research Lab, ITRL.
    Kottenhoff, Karl
    KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
    Självkörande fordon som komplement till kollektivtrafiken – en förstudie för Stockholm2017Rapport (Annet vitenskapelig)
  • Disputas: 2019-06-13 09:30 Sal B, Kista
    Farshin, Alireza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab).
    Realizing Low-Latency Internet Services via Low-Level Optimization of NFV Service Chains: Every nanosecond counts!2019Licentiatavhandling, monografi (Annet vitenskapelig)
    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.

  • Janson, Svante
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Analysis and Probability Theory..
    Linusson, Svante
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    Proportionella val inom kommunfullmäktige2019Rapport (Annet vitenskapelig)
    Abstract [sv]

     Vi diskuterar två olika problem som kan uppstå vid proportionella val i kommunfullmäktige och regionfullmäktige når ett parti försöker en kupp genom att utan samtycke gå i kartell med ett annat parti vid val till nämnd eller styrelse, vilket aktualiserades i åtminstone ett par fall hösten 2018. Det första problemet är vad sådana oönskade valkarteller kan få för effekter, och vilka möjligheter det finns för ett parti att skydda sig från att bli del i en oönskad valkartell. Det andra problemet är att i en sådan valkartell kan ett parti genom att splittra upp sina kandidater strategiskt  på flera olika valsedlar få fler platser i en nämnd är vad som är proportionellt. Detta andra problem bottnar i att lagen om proportionella val stipulerar att Thieles metod skall användas för fördelning inom kartellen. På detta problem finns en enkel matematisk lösning och vi argumenterar för att man skall byta till Phragméns metod som används för motsvarande val till utskott i riksdagen.

  • Lindberg, Boel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Resilience in urban hydrology: A study of storm water management in the municipality of Stockholm2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • Disputas: 2019-05-10 15:00 D3, Stockholm
    Dastory, Linda
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Nationalekonomi.
    Innovation, Technical Change and the Labour Market2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-09 10:00 Kollegiesalen, Stockholm
    Sophonrat, Nanta
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Pyrolysis of mixed plastics and paper to produce fuels and other chemicals2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Inbyggda styrsystem.
    Automated Support for the Architecting of Distributed Embedded Systems: Methods and Analysis for Industrial Adoption2017Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-10 09:30 Sal B, Stockholm
    Roozbeh, Amir
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS. Ericsson Research.
    Toward Next-generation Data Centers: Principles of Software-Defined “Hardware” Infrastructures and Resource Disaggregation2019Licentiatavhandling, monografi (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-17 13:00 Ka-Sal B (Sal Peter Weissglas), Stockholm
    Ivanisevic, Nikola
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Circuit Design Techniques for Implantable Closed-Loop Neural Interfaces2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • Sun, Tao
    et al.
    Tianjin University.
    Lian, Binbin
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Zhang, Jiateng
    Tianjin University.
    Song, Yimin
    Tianjin Univeristy.
    Kinematic calibration of a2-DoF over-constrained parallel mechanism using real inverse kinematics2018Inngår i: IEEE Access, E-ISSN 2169-3536, Vol. 6, s. 67752-67761Artikkel i tidsskrift (Fagfellevurdert)
  • Disputas: 2019-05-07 10:00 Kollegiesalen, Stockholm
    Nikouie, Mojgan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Design, Construction and Evaluation of a StackedPolyphase Bridges Converter for Integrated ElectricDrive Systems in Automotive ApplicationsMOJGAN NIKOUIEDoctoral ThesisStockholm, Sweden2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-06 13:00 FA31, Stockholm
    Petrou, Georgia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Investigating mucin interactions with diverse surfaces for biomedical applications2019Licentiatavhandling, med artikler (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-10 10:00 FA-31, Stockholm
    Kianirad, Hoda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Studies on Domain Dynamics in Nonlinear Optical Ferroelectric Oxide Crystals2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Nikouei Harnefors, Mojgan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    DC-link and machine design considerationsfor resonant controllers adopted in automotive PMSM drivesInngår i: Artikkel i tidsskrift (Fagfellevurdert)
  • Nikouie, Mojgan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Wallmark, Oskar
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Torque-Ripple Minimization for Permanent-MagnetSynchronous Motors Based on Harmonic Flux Estimation2018Konferansepaper (Fagfellevurdert)
    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, Skolan för elektroteknik och datavetenskap (EECS).
    Zhang, Hui
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Wallmark, Oskar
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Highly integratedelectric drives system for tomorrow’s EVs and HEVs2017Konferansepaper (Fagfellevurdert)
    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, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    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 poäng / 30 hpOppgave
    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.

  • Disputas: 2019-05-03 10:00 D2, Stockholm
    Müller, Matias
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Regret and Risk Optimal Design in Control2019Licentiatavhandling, monografi (Annet vitenskapelig)
    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.

  • Disputas: 2019-06-05 10:00 Q2, Stockholm
    Schillinger, Philipp
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Bosch Center for Artificial Intelligence.
    Specification Decomposition and Formal Behavior Generation in Multi-Robot Systems2019Doktoravhandling, monografi (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-03 09:00 Air & Fire, Solna
    Jess, David Unnersjö
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biofysik.
    High-resolution Imaging of Cleared and Expanded Kidney Tissue Samples2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • Disputas: 2019-05-03 10:00 Ka-Sal B (Sal Peter Weissglas), Kista
    Hou, Shuoben
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Silicon Carbide High Temperature Photodetectors and Image Sensor2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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, Skolan för teknikvetenskap (SCI).
    Eriksson, Hanna
    KTH, Skolan för teknikvetenskap (SCI).
    Night-Time Observations of Earth: Satellite Orbit Modied for UHECR Observations2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    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, Skolan för industriell teknik och management (ITM), Energiteknik.
    Izaguirre Carbonell, Javier
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    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 poäng / 30 hpOppgave
    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, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Morana, R.
    Drakopoulos, M.
    Bhadeshia, H. K. D. H.
    Designing steel to resist hydrogen embrittlement Part 2: precipitate characterisation2018Inngår i: Materials Science and Technology, Vol. 34, nr 14, s. 1747-1758Artikkel i tidsskrift (Fagfellevurdert)
    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, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Hallme, Elin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    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 poäng / 30 hpOppgave
    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, Skolan för industriell teknik och management (ITM), Energiteknik.
    Experimental Study of Heat Transfer Coefficient and Film Cooling Effectiveness2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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, Skolan för elektroteknik och datavetenskap (EECS).
    Service Aware Traffic Distribution in Heterogeneous A2G Networks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Gyllenram, Rutger
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Samuelsson, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Assesment of Scrap-based Production for Low Phosphorus Stainless Steel2018Konferansepaper (Fagfellevurdert)
    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, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. 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 boreholes2013Inngår i: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 56, s. 56-61Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • Benfeitas, Rui
    et al.
    KTH, Centra, Science for Life Laboratory, SciLifeLab. Royal Institute of Technology, KTH.
    Bidkhori, Gholamreza
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Mukhopadhyay, Bani
    Klevstig, Martina
    Arif, Muhammad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Systembiologi.
    Zhang, Cheng
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Lee, Sunjae
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Cinar, Resat
    Nielsen, Jens
    Uhlén, Mathias
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Boren, Jan
    Kunos, George
    Mardinoglu, Adil
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Characterization of heterogeneous redox responses in hepatocellular carcinoma patients using network analysis2019Inngår i: EBioMedicine, E-ISSN 2352-3964Artikkel i tidsskrift (Fagfellevurdert)
  • Svensson, Maria C.
    et al.
    Borg, David
    Zhang, Cheng
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Hedner, Charlotta
    Nodin, Björn
    Uhlén, Mathias
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Mardinoglu, Adil
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Leandersson, Karin
    Jirström, Karin
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