123456 1 - 50 of 285
rss atomLink to result list
Permanent link
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
  • Goncalves, Sofia
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Feasibility study of an EV management system to provide Vehicle-to-Building considering battery degradation2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The recent increase of electric cars adoption will inuence the electricity demand in the distributionnetworks which risks to be higher than the maximum power available in the grid, if not well planned. Forthis reason, it is on the DSOs and TSOs's interest to plan carefully coordinated charging of a bulk of EVsas well as assess the possibility of EVs acting as energy storages with the Vehicle-to-Grid (V2G) or Vehicleto-Building (V2B) capability. When parked and plugged into the electric grid, EVs will absorb energy andstore it, being also able to deliver electricity back to the grid/building (V2G/B system).This can be anoptimized process, performed by an aggregator, gathering multiple EVs that discharge the battery into thegrid at peak time and charge when there is low demand i.e. overnight and o-peak hours.Numerous studies have investigated the possibility of aggregating multiple EVs and optimizing theircharging and discharging schedules for peak load reduction or energy arbitrage with participation in theelectricity market. However, no study was found for optimizing a shared eet of EVs with daily reservationsfor dierent users trying to perform V2B. In this study an optimization modelling algorithm (mixed integerlinear problem - MILP) that manages the possible reservations of the shared eet of EVs, coordinates thecharging and discharging schedules, and provides V2B (Vehicle-to-Building), with the objective of minimizingenergy costs and accounting with battery ageing has been developed. A case study with real data for abuilding is carried out modelling dierent number of EVs for two dierent days in year 2017, one in Marchand other in June.Results show that the prots are higher for all cases when introducing V2B as compared to a no optimizationscenario: V2B with battery degradation (50 ore/kWh) has decreased daily variable electricity costsbetween 54 and 59% in March and 60 and 63% for June when compared without smart charging. Integrationof battery degradation cost in V2B applications is necessary and inuences signicantly the chargingand discharging strategies adopted by EV and nally the total daily costs: The total daily cost increaseby maximal 10% for the day in March and 13% for the day in June when comparing the scenario that hasstationary battery and uses only-charging model for EVs with the scenario applying V2B mode consideringa degradation cost of 80 ore/kWh.

  • Granfors, Ville
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Server Design to Ensure Quality and Fairness in Mobile Crowdsourcing2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mobile crowdsourcing solves complex problems by utilizing the untapped power of a crowd, connected through the fantastic mobile devices we use in our daily life. These gadgets are equipped with a versatile set of sensor that could be used for gathering data about a specific location in combination with questions to the human carrier. Common problems in crowdsourcing systems is how to ensure that the contributed data from the crowd is of a high quality and how to do task allocation fairly. A large population of users is often needed to ensure a high quality of data and coverage, every participant is important and the system have to do be designed with the population in mind.In this thesis we discuss the responsibilities of the server in a crowdsourcing system and presents a system model which tries to tackle the problems of quality and fairness. A prototype of the system model was developed (CrowdS) to determine its potential, for both Android and iOS devices.A long running test was performed to evaluate the performance of CrowdS with the main focus on determine how well the system performed in terms of coverage of the search area and fairness of earnings and prices. The test was executed on both platforms for a couple of weeks. The vast majority of all completed tasks were finished within 10 minutes of being created, with a median time of 3 minutes and 32 seconds seconds. Jain’s fairness index measured an overall high fairness for both the price of tasks at 0.944 and the earnings made by participants at 0.941. The radius of the search area had to be extended to maximum of 800 meters for roughly on third of the tasks to find the required number of participants.

  • Kidron, Matias
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Detecting minimoons in the Earth-Moon system with microsatellite compatible technologies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Minimoons, Earth’s temporarily-captured orbiters, are excellent candidates for asteroidmining technology demonstrations and general asteroid studies because of their relativelylong stay in the vicinity of Earth. In this thesis, microsatellite compatible surveillancetechnologies are discussed and the suitability of various locations in the Earth-Moon systemfor minimoon surveillance is examined. This is done to acquire knowledge on whichtype of an orbit a minimoon-surveying-microsatellite could be placed on.The instantaneous visible fraction of the minimoon steady-state population is the figureof merit when comparing surveillance systems and locations. The visible fraction is estimatedby simulating the distribution of visible minimoons in the sky-plane. The objectsin the simulated sky-plane are synthetic minimoons, which are generated in large numbersaccording to the geocentric 6-dimensional-residence-time-distribution of minimoons, andthus, the bin values of the sky-plane distribution can be thought of as instantaneous probabilitiesfor containing a detectable minimoon within certain ecliptic latitude-longituderange.The visible fractions are estimated for various locations with given surveillance systemperformance. Multiple microsatellite compatible surveillance technology configurationsare examined as well as the e↵ect of limiting magnitude and maximum angular velocity.Minimoons are faint and fast moving objects and thus the use of synthetic tracking algorithmis beneficial and considered. Only visual band surveillance systems with aperturesizes less than 0.30 m and minimoons with diameter sizes larger than 0.50 m are consideredin the simulations.

  • Bång, Olivia
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Teknik på Youtube: En diskursanalys av teknik i Youtubevideor2019Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Technology as a subject in Swedish high schools faces many problems. The subjects purpose and content has gone through significant changes over the years, and today (2018) less than half of all active teachers possess the right qualifications. There is therefore a need to aid these teachers in planning and executing their classes, to ensure a quality education for our pupils.

    With the assumption that a big part of learning is to be able to connect knowledge gathered outside of school to the academic knowledge acquired in school, the purpose of this paper was to analyse which technological discourses high school pupils could acquire outside of school. These discourses were then compared to the technological discourses that can be found in schools, to help aid the technology teachers’ planning of their classes.

    To find out where pupils are exposed to technology discourses on their free time, this paper looked to the social video-sharing platform, Youtube. Practically all Swedish kids between the ages of 12 to 15 use Youtube, and 86 % of them use it every day. At Swedish award shows the Swedish Youtuber and Influencer Therese Lindgren won titles such as Youtuber of the year and the Kids favourite vlogger. Therese Lindgrens Youtube series, “Therese testar teknik”, won the title of Series of the year. This seems to tell us that Therese Lindgren and her show “Therese testar teknik” are popular among kids and could potentially influence their view of technology.

    A selection of episodes from the series were picked to be analysed, to find out which technological discourse was represented in these videos, and how it compared to the discourses in schools. The results showed that the videos presented technology comparable to schools, but with some differences in focus. In the videos, technology was presented as the artefacts and systems of artefacts used in an activity to solve a problem or a task, that were affected by natural sciences and affected society.

    Aside from the parts of the technology discourse that was comparable to the ones in schools, the videos also presented emotions connected to technology, through non-verbal communication. The videos presented technology as something fun and exciting, something that can influence the viewers’ own attitude towards technology.

  • Savva, Androula
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Assessment of Functional Connectivity Impairment in Rat Brains2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    While the rodent model has long been used in brain research, there exists no standardisedprocessing routine that can be employed for analysis and investigation of disease models. Thepresent thesis attempts to investigate a diseased brain model by implementing a collection ofscripts, combined with algorithms from existing neuroimaging software, and adapting themto the rodent brain, in an attempt to examine when and how monaural canal atresia affectsthe functional connectivity of the brain. We show that it is possible to use software tailoredto the human brain to pre-process the rodent model. Following conventional pipelines andresting state functional MRI (rs-fMRI)-specific strategies, the developed processing routineimplements the most basic steps suggested in literature. On the single-subject level, skullstripping was done using Mialite software, motion correction and distortion correction werebased on FMRIB software library (FSL) algorithms and motion artefacts were removed usingICA-based Automatic Removal Of Motion Artifacts (ICA-AROMA). Following denoising,normalisation to standard space, smoothing and temporal filtering, group level analysis wasperformed. A univariate, hypothesis-driven method and a multivariate, data-driven methodwere used for group comparison and statistical inference. While seed-based correlationanalysis (SCA) did not return any significant results, independent component analysis (ICA) identified two components that show activation in areas of interest.

  • Nygren, Johan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Active Noise Control with Virtual Reference Signals in an FXLMS Algorithm2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Noise pollution from road traffic is one of the greatest environmental issues in modern day, and the social cost for road traffic noise was estimated to over 16 billion SEK per year in Sweden in2014. Passive or active control methods can be used to reduce the noise. Active control methods or active noise control is more suitable for attenuating noise in lower frequencies. Active noise control reduces noise by eliminating the noise with a secondary source. There are different control strategies to construct an active noise control system, where the update of the secondary sourceis controlled by an algorithm. There are several different algorithms that are possible to use, and one option is to use a Feedforward Filtered-X Least-Mean-Square (FXLMS) algorithm. It uses control positions where the noise is meant to be reduced and reference signals that measure the noise upstream prior the secondary source. FXLMS also uses a model of the secondary source path to the control position in order to ensure convergence of the algorithm. Although the use of multiple reference signals increases the accuracy of the algorithm, it also increases the convergence time and the practical cost of such an installation. Unfortunately, it can require many reference signals to obtain a sufficient noise reduction when the unwanted noise source is complex and has multiple propagation paths.This study investigates the possibility of producing a new, reduced set of reference signals with a linear combination of the original reference signals that still contain the majority of information needed for suficient noise reduction. This new set of reference signals are sometimes called virtual reference signals. Three different methods of virtual reference signals are analysed; first a constant method using singular-value decomposition on the covariance of the reference signals, second another constant method using singular-value decomposition on the covariance of response estimate from each corresponding reference signal, third an adaptive algorithm updating the linear combination to adapt for incoming data. The different strategies are tested on road test measurements at three different constant speeds, 40km=h; 80km=h and 120km=h, and on data generated from a numerical vehicle model in COMSOL.The results from the analysis indicates that the virtual reference signals could sufficiently reproduce information from the original reference signals to obtain a similar noise reduction with fewer reference signals. However, the virtual reference signals with the adaptive algorithm could not manage to track a transient system where the signal amplitudes are varying over time. Further work is needed to analyse the limits and requirements to obtain virtual reference signals that can represent and track a system even for transient events.

  • Hadzalic, Deniz
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Application of neural networks for prediction of subjectively assessed interior aircraft noise2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Products are increasingly judged by their acoustic performance; and during the last decades, sound quality in general has gained a lot of attention, both from academia and companies. An obstacle in the evaluation of the sound quality is that jury testing is time consuming and require human resources. In an attempt to overcome these limitations, neural networks have been applied in this work with the objective to find a relation between human acoustic perception and a quantity possible to physically measure. For this purpose, 30 of 170 sound samples of interior aircraft noise have been subjectively assessed  during jury testing with 40 participators. With extracted psychoacoustic features from the sound samples and the obtained results from the jury testing, a shallow neural network (SNN) with one hidden layer is trained and tested. The prediction performance of the SNN is compared with another alternative method - multiple linear regression. The evaluation of the remaining un-assessed sound samples is predicted by the trained SNN and implemented in the deep learning neural networks, such as Convolutional Neural Network (CNN) and Recurrent Neural Network (RNN).

  • Firdaus, Alfi Hadi
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    System-wide LCC Calculation for Novel Brake Block Material in Nordic Condition2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the main issues of cast-iron block brake material is high noise. Nowadays, train operators tend to change the brake block material from cast-iron to composite material. However, composite block brake materials are likely to produce more wear than cast-iron block brakes, degrading the dynamic behavior of the vehicle on the track. Therefore, comparison of the dynamic behavior and the maintenance cost of each block brake material of the train has been performed. The dynamic behavior is analyzed using GENSYS software and the maintenance cost analysis is done by using the Universal Cost Model developed in the EU project Roll2Rail. The iron ore train that operates in Malmbanan has been used as the simulation model. One-wheel profile before changing the block brake material before 2010 and two-wheel profiles after changing the block brake material after 2010 have been used for simulation. Certain radii, cant, vehicle speeds and wheel-rail friction coefficients has been taken into consideration in the simulations. After that, the wheel and track maintenance costs have been taken into consideration for analyzing the Universal Cost Model. The simulation results show that the wheel profiles after changing the block brake material possess higher risk of RCF than wheel profile before changing the brake block material. The UCM calculation show that the wheel profile after changing brake material leads to higher track maintenance costs, 9.3% higher for new1 and 2.8% higher for new2 wheel profiles, compared to the worn wheel profile before changing brake material. Moreover, The UCM calculation show that the wheel profile after changing brake material leads to higher wheel maintenance costs, 1.04% higher for new1 and 4.3% higher for new2 wheel profiles, compared to the worn wheel profile before changing brake material. The total of maintenance cost also shows that the wheel profile after changing brake material leads to higher maintenance costs, around 2-4%, compared to the worn profile before changing brake material. 

    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    GPS-oscillation-robust Localization and Visionaided Odometry Estimation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    GPS/IMU integrated systems are commonly used for vehicle navigation. The algorithm for this coupled system is normally based on Kalman filter. However, oscillated GPS measurements in the urban environment can lead to localization divergence easily. Moreover, heading estimation may be sensitive to magnetic interference if it relies on IMU with integrated magnetometer. This report tries to solve the localization problem on GPS oscillation and outage, based on adaptive extended Kalman filter(AEKF). In terms of the heading estimation, stereo visual odometry(VO) is fused to overcome the effect by magnetic disturbance. Vision-aided AEKF based algorithm is tested in the cases of both good GPS condition and GPS oscillation with magnetic interference. Under the situations considered, the algorithm is verified to outperform conventional extended Kalman filter(CEKF) and unscented Kalman filter(UKF) in position estimation by 53.74% and 40.09% respectively, and decrease the drifting of heading estimation.

  • Public defence: 2019-04-12 10:15 Kollegiesalen, Stockholm
    B. da Silva Jr., Jose Mairton
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Optimization and Fundamental Insights in Full-Duplex Cellular Networks2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The next generations of cellular networks are expected to provide explosive data rate transmissions and very low latencies. To meet such demands, one of the promising wireless transmissions candidates is in-band full-duplex communications, which enable wireless devices to simultaneously transmit and receive on the same frequency channel. Full-duplex communications have the potential to double the spectral efficiency and reduce the transmission delays when compared to current half-duplex systems that either transmit or receive on the same frequency channel. Until recently, full-duplex communications have been hindered by the interference that leaks from the transmitter to its own receiver,the so-called self-interference. However, advances in digital and analog self-interference suppression techniques are making it possible to reduce the self-interference to manageable levels, and thereby make full-duplex a realistic candidate for advanced wireless systems.

    Although in-band full-duplex promises to double the data rates of existing wireless technologies, its deployment in cellular networks must be gradual due to the large number of legacy devices operating in half-duplex mode. When half-duplex devices are deployed in full-duplex cellular networks, the user-to-user interference may become the performance bottleneck. In such new interference situation, the techniques such as user pairing, frequency channel assignment, power control, beamforming, and antenna splitting become even more important than before, because they are essential to mitigate both the user-to-user interference and the residual self-interference. Moreover, introduction of full- duplex in cellular networks must comply with current multi-antenna systems and, possibly, transmissions in the millimeter-wave bands. In these new scenarios, no comprehensive analysis is available to understand the trade-offs in the performance of full-duplex cellular networks.

    This thesis investigates the optimization and fundamental insights in the design of spectral efficient and fair mechanisms in full-duplex cellular networks. The novel analysis proposed in this thesis suggests new solutions for maximizing full-duplex performance in the sub-6 GHz and millimeter-wave bands. The investigations are based on an optimization theory approach that includes distributed and nonconvex optimization with mixed integer-continuous variables, and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on fundamental questions such as which antenna architecture should be used and whether full-duplex in the millimeter-wave band is feasible. The results establish fundamental insights in the role of user pairing, frequency assignment, power control and beamforming; reveal the special behaviour between the self-interference and user- to-user interference; analyse the trade-offs between antenna sharing and splitting for uplink/downlink signal separation; and investigate the role of practical beamforming design in full-duplex millimeter-wave systems. This thesis may provide input to future standardization process of full-duplex communications.

  • Public defence: 2019-06-10 13:00 Kollegiesalen, Stockholm
    Ahlin Marceta, Jesper
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Authenticity in Bioethics: Bridging the Gap between Theory and Practice2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this doctoral thesis is to bridge the gap between theoretical ideals of authenticity and practical authenticity-related problems in healthcare. In this context, authenticity means being "genuine," "real," "true to oneself," or similar, and is assumed to be closely connected to the autonomy of persons. The thesis includes an introduction and four articles related to authenticity. The first article collects various theories intended to explain the distinction between authenticity and inauthenticity in a taxonomy that enables oversight and analysis. It is argued that (in-)authenticity is difficult to observe in others. The second article offers a solution to this difficulty in one theory of authenticity. It is proposed that under certain circumstances, it is morally justified to judge that the desires underlying a person's decisions are inauthentic. The third article incorporates this proposition into an already established theory of personal autonomy. It is argued that the resulting conceptualization of autonomy is fruitful for action-guidance in authenticity-related problems in healthcare. The fourth article collects nine cases of possible authenticity-related problems in healthcare. The theory developed in the third article is applied to the problems, when this is allowed by the case-description, to provide guidance with regard to them. It is argued that there is not one universal authenticity-related problem but many different problems, and that there is thus likely not one universal solution to such problems but various particular solutions.

  • Guinaudeau, Alexandre
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Estimating the probability of event occurrence2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In complex systems anomalous behaviors can occur intermittently and stochastically. In this case, it is hard to diagnose real errors among spurious ones. These errors are often hard to troubleshoot and require close attention, but troubleshooting each occurrence is time-consuming and is not always an option.

    In this thesis, we define two different models to estimate the underlying probability of occurrence of an error, one based on binary segmentation and null hypothesis testing, and the other one based on hidden Markov models. Given a threshold level of confidence, these models are tuned to trigger alerts when a change is detected with sufficiently high probability.

    We generated events drawn from Bernoulli distributions emulating these anomalous behaviors to benchmark these two candidate models. Both models have the same sensitivity, δp ≈ 10%, and delay, δt ≈ 100 observations, to detect change points. However, they do not generalize in the same way to broader problems and provide therefore two complementary solutions.

  • Hagrot, Joel
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A Data-Driven Approach For Automatic Visual Speech In Swedish Speech Synthesis Applications2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project investigates the use of artificial neural networks for visual speech synthesis. The objective was to produce a framework for animated chat bots in Swedish. A survey of the literature on the topic revealed that the state-of-the-art approach was using ANNs with either audio or phoneme sequences as input.

    Three subjective surveys were conducted, both in the context of the final product, and in a more neutral context with less post-processing. They compared the ground truth, captured using the deep-sensing camera of the iPhone X, against both the ANN model and a baseline model. The statistical analysis used mixed effects models to find any statistically significant differences. Also, the temporal dynamics and the error were analyzed.

    The results show that a relatively simple ANN was capable of learning a mapping from phoneme sequences to blend shape weight sequences with satisfactory results, except for the fact that certain consonant requirements were unfulfilled. The issues with certain consonants were also observed in the ground truth, to some extent. Post-processing with consonant-specific overlays made the ANN’s animations indistinguishable from the ground truth and the subjects perceived them as more realistic than the baseline model’s animations.

    The ANN model proved useful in learning the temporal dynamics and coarticulation effects for vowels, but may have needed more data to properly satisfy the requirements of certain consonants. For the purposes of the intended product, these requirements can be satisfied using consonant-specific overlays.

  • Antaris, Stefanos
    Link injection for boosting information spread in social networks2014In: Social Network Analysis and Mining, ISSN 1869-5450, E-ISSN 1869-5469, Vol. 4, no 1, article id 236Article in journal (Refereed)
  • Vakali, Athena
    et al.
    Giatsoglou, Maria
    Antaris, Stefanos
    Social networking trends and dynamics detection via a cloud-based framework design2012Conference paper (Refereed)
  • Karagiannidis, Savvas
    et al.
    Antaris, Stefanos
    Zigkolis, Christos
    Vakali, Athena
    Hydra: an open framework for virtual-fusion of recommendation filters2010Conference paper (Refereed)
  • Stojanovic, Milan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Teknik för dokumentering avmöten och konferenser2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Documentation of meetings and conferences is performed at most companies by one or more people sitting at a computer and typing what has been said during the meeting. This may lead to typing mistakes or incorect perception by the person who records. The human factor is quite large. This work will focus on developing proposals for new technologies that reduce or eliminate the human factor, thus improving the documentation of meetings and conferences. It represents a problem for many companies and institutions, including Seavus Stockholm, where this study is conducted. It is assumed that most of the companies do not document their meetings and conferences in video or audio format, so this study will therefore only be about text-based documentation.The aim of this study was to investigate how to implement new features and build a modern conference system, using modern technologies and new applications to improve the documentation of meetings and conferences. Speech to text in combination with speech recognition is something that has not yet been implemented for such a purpose, and it can facilitate documenting meetings and conferences.To complete the study, several methods were combined to achieve the desired goals. First, the projects scope and objectives were defined. Then, based on analysis of the observations made in the company documenting process, a design proposal was created. Following this, interviews with the stakeholders were conducted where the proposals were presented and a requirement specification was created. Then the theory was studied to create an understanding of how different techniques work to then design and create a proposal for the architecture.The result of this study contains a proposal for architecture that shows that it is possible to implement these techniques to improve the documentation process. Furthermore, possible use cases and interaction diagrams are presented that show how the system may work.Although the proof of the concept is considered to be satisfactory, additional work and testing is needed to fully implement and integrate the concept into reality.

  • Wang, Chen
    KTH, School of Engineering Sciences (SCI), Physics.
    A Preliminary Design Study for a Small Passive Lead-bismuth Cooled Fast Reactor2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Andersson, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Weurlander, Maria
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Peer review of laboratory reports for engineering students2018In: European Journal of Engineering Education, ISSN 0304-3797, E-ISSN 1469-5898, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Here, we present a module to introduce student peer review of laboratoryreports to engineering students. Our findings show that students werepositive and felt that they had learnt quite a lot from this experience.The most important part of the module was the classification scheme.The scheme was constructed to mimic the way an expert would arguewhen making a fair judgement of a laboratory report. Hence, our resultsmay suggest that the success of the module design comes from activelyengaging students in work that is more related to ‘arguing like anexpert’ than to only supply feedback to peers, which in such a casewould implicate a somewhat new direction for feedback research. Forpractitioners, our study suggests that important issues to consider in thedesign are (i) a clear and understandable evaluation framework, (ii)anonymity in the peer-review process and (iii) a small external motivation.

  • Phongsawat, Chonticha
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Effect of nutrient limitation in chemostat cultures on amino acid excretion in Clostridium thermocellum2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Introduction: Clostridium thermocellum is considered a model organism for consolidated bioprocessing, due to its ability to hydrolyze lignocellulosic biomass more efficiently than many other organisms and to produce ethanol.In order to meet the industrial requirements of ethanol yield and titer, metabolic engineering efforts have been made resulting in a strain that successfully displays increased ethanol yield with reduced amount of some byproducts.However, the ethanol yield in this engineered strain still does not meet the industrial requirements and significant amounts of amino acids are still produced. To attempt to decrease the level of amino acid excretion intended to improve the ethanol yield in C. thermocellum, it is essential to understand its metabolism and how it is affected by different cultivation conditions and mediumcompositions. This study aimed to gain an insight in how carbon- and nitrogenlimitation affect amino acid excretion in C. thermocellum, with the hypothesisthat excess of carbon and nitrogen yields more amino acid excretion. Methods: Mass-balance based calculations of rates and yields were used to analyze the metabolism of a wild-type of C. thermocellum (DSM 1313) grownanaerobically in carbon- or nitrogen-limiting chemostats. For this, Low-Carbonmedium containing, respectively, cellobiose (5 g/L) and urea (0.15 g/L) as the limiting nutrient was used. Both cultivations were performed at 55 °C, pH 7.0and 400 RPM shaking at a dilution rate of 0.1 h-1.Conclusions: Considering yields of total amino acids excreted in both limitations, it was hypothesized that C. thermocellum exploited the amino acid excretion to maintain carbon balance around the pyruvate node caused by excess of the carbon. Based on yield of valine excreted in particular, it was hypothesized that amino acid excretion was used to maintain redox balance in the metabolism of C. thermocellum, where malate shunt could play a major role.However, results of the Carbon-limitation did not allow any conclusion of nitrogen excess having an effect on amino acid excretion in C. thermocellum.

  • She, Baoqing
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Deep Learning for Error Prediction In MIMO-OFDM system With Maximum Likelihood Detector2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To increase link throughput in multi-input multi-output (MIMO) orthogonal frequencydivision multiplexing (OFDM) systems, transmission parameters such as code rate andmodulation order are required to be set adaptively. Therefore, block error rate (BLER)becomes a crucial measure which illustrates the quality of the link, thus being used in LinkAdaptation (LA) to determine the transmission parameters. However, existing methods topredict BLER are only valid for linear detectors, e.g. Minimum Mean Square Error (MMSE)detector [1]. In this thesis, we show that signal-to-interference-plus-noise ratio (SINR)exists in MIMO-OFDM system with MLD (maximum likelihood detection). Then, a machinelearning based method with Deep Neural Network (DNN) is proposed to analyze therelation between input features (channel matrix, modulation and coding scheme (MCS),signal-to-noise ratio(SNR)) and labels (CRC). Results shows that the classification of DNNis good. However, there is still deviation when compared output of DNN with thesimulated BLER.

  • Nordahl, Bertil
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Fuktskador i förskolor – reparation eller nybyggnation?2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Several kindergartens in Nynäshamn are damaged by damp. The damage is so severe that only two options remain; extensive repairs or demolition and build new buildings. Which option is best from a building technology point of view? In search for the answer Midgård’s kindergarten has been studied. That building is especially interesting for two reasons:

    • It is the first kindergarten damaged by damp in Nynäshamn to go through extensive repairs.

    • The other kindergartens damaged by damp in Nynäshamn have a similar construction.

    The conclusion is that it is better to demolish and build a new building. The main reason is the restrictions set by the building’s original shell. It makes it impossible to live up to today’s all building standards for kindergartens.

  • Bharadwaj Sriram, Adhitya
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Concealment Materials and Techniques for mm-Wave Advanced Antenna Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With theadventofthe5Gtechnologystandardforcommunication,itisesti-mated thataround50billiondevicesaroundtheworldwillbeinterconnectedunder thisstandard [1]. Thishaspromptedtheneedtoinvestigatenewma-terials, technologiesandmethodstoconcealantennasforpreservingtheaes-thetic valueofurbancenters,andpreventingtheseantennasystemsfrombeingidentifiedordamaged.Theaimofthisthesisworkwastoidentifypossiblematerials andinvestigatemethodsforconcealingEricsson’s5Gmm-WaveAd-vancedAntennaSystem(AAS)RadioBaseStations.Astudyofeconomicallyviable, commerciallyavailablematerialsforconcealment,andmethodstodeter-mine theirdielectricpropertieswasdone.Apracticalinvestigationoftheeffectsome availableconcealmentmaterialsontheRFperformanceofthemm-Wavebase stationbeams,wasalsoperformed.Theresultsfromtheinvestigationsand measurementsperformedledtosomeusefulconclusionsandunderstand-ing aboutthevariousconcealmentmaterialsolutions.Overall,theinvestigatedconcealmentmaterialswerefoundtohavetwoprominenteffects:1. Reduction inEIRP(EquivalentIsotropicRadiatedPower)ofthebasestation beams(attenuation).2. Distortion intheshapeofthebasestationbeams.The boresightbeamsforalltheinvestigatedcaseswerefoundtobeattenu-ated(effect 1)bytheconcealments,butthesteeredbeamswerefoundtobebothattenuatedindistorted(effect2)bytheconcealments.Inparticular,con-cealmentswithathindielectricmaterialmeshstructurewerefoundtohavetheleast effectonthebasestationbeams.Allotherthicker(> 0=2), compositeconcealmentsandeventhosewithpurefoamstructures,werefoundtohaveanoticeable effectonthebasestationbeams.Inconclusion,thindielectricmesh,films andpaintscouldhencebeofinterestasconcealmentsolutionsforfurtherinvestigationsmovingforward.

  • Du, Jiangfeng
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Self-adaptive and hierarchical membership management in distributed system2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cloud computing is widely deployed in industry, enablingcustomers to save infrastructure acquisition and networkdeployment costs. To provide better performance of applicationsdriven by cloud computing, management of theresource pool in the cloud needs to be effective. For efficientcommunication within the resource pool, an overlay ofnodes is formed. Membership management maintains themembership lists and relationship for all nodes in the overlay,detects the member changes, and exposes the membershiplist to other management components or upper layerservices. However, most existing solutions only maintain arelative static overlay which cannot reflect the real-time anddynamic network and system conditions in the systems, andthus the performance of those tasks or services dependingon the membership management will be less optimized.To deal with the problem, we proposed and implementeda self-adaptive and hierarchical membership managementsystem. The structure of the overlay could be dynamicallychanged according to predefined and real-time costvalues between each pair of nodes. A transfer approach isproposed in order to move one node from a cluster to anothercluster and meanwhile replace a high-cost link witha low-cost link; a merge approach is proposed in order todecrease the amount of clusters with relatively small sizeand improve the connectivity of the whole overlay network.Ideally, the resulting overlay network will possess a fullyconnected and tree-based hierarchical structure with minimumoverall cost. The optimized structure could benefitthe services running on top, such as resource schedulingand task placement.The system is evaluated in an emulated environment.Results from experiments show that the structure couldadapt to cost changes and the overall cost can be reducedwhen the parameters are set properly. The communicationoverhead incurred by messages keeps low for non-leadernodes, grows with the level for leaders nodes and does notincrease a lot with the number of nodes in the system. Thefailure of nodes can be detected with high accuracy andrelatively low latency. Moreover, the whole structure couldrecover from the events like leader failure timely.

  • Casas Moreno, Xavier
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Noise modelling for high-throughput super-resolution microscopy2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Super-resolution fluorescence microscopy is an emerging imaging fieldthat aims at breaking the di↵raction barrier of light based on state transitionin fluorescent molecules. Current challenges in the existing approachare to achieve large field of views, fast recordings and increasing the imagequality.The Advanced Bio-Imaging group at the Science for Life Laboratory inStockholm invented the Molecular Nanoscale Live Imaging with SectioningAbility (MoNaLISA), a microscope that reaches high spatial resolution(45-65 nm) with low light intensities (kWcm

  • Vasudevan, Deepak
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Water Distribution Networks: Leakage Management using Nonlinear Optimization of Pressure2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The eective management of water distribution systems is gaining tremendousfocus within the scientic community thanks to the Internet of Things.This report is an exploration attempt into the mathematical optimization ofa water distribution network under the inuence of leakages caused by deteriorationwithin the distribution network. The optimization process is carriedout in a two phase manner involving the optimal placement of pressure valves,followed by the optimal control of the valves in the presence of known leakswithin the network. The optimization framework addresses the minimisationof the average network pressure in an extended time setting by imposingthe hydraulic equations as nonlinear constraints. The hydraulic components,namely the pressure reduction valves, are modelled as integer variables leadingto a non-convex and non-linear optimization problem that falls under theclass of optimization problems known as mixed-integer nonlinear programming(MINLP). The exercise implements two reformulation methods that solves theMINLP problem as a sequence of regular nonlinear programs (NLPs), and alsopresents the hydraulic simulation results of the implementation. While thereis sucient research on water network optimization using various mathematicalmethods, this study endeavours to combine a leakage model within theoptimization framework and presents the ndings of the analysis. In addition,the report also includes the outcomes of the simulation on a real distributionnetwork simulated under varying demand conditions.

  • Damström, Julia
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Life cycle cost analysis of lithium ion batteries using different charging strategies: case study Stockholm Arlanda airport2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To reach existing climate goals, the transportation sector need to be readjusted. One alternative is to use electricityas fuel. A positive trend is that the market share of electric vehicles is increasing, much thanks to that the ba�eryprices are decreasing. One ba�ery that is commonly used in electric vehicles is the lithium ion ba�ery (LIB), whichprice has decreased and is expected to continue to decrease. One useful tool when investigating the costs is lifecycle cost (LCC) analysis.One goal of this master thesis is to perform a systematic literature review on existing research about LCC analysison LIB. �e literature review results show that the found, existing research mainly focuses on LIBs and life cycleassessments. �e focus on LCC analysis is concluded to be small, based on the found published literature.�e main goal of this project is to investigate the charging strategy impacts on LIB lifetime from an LCC perspectiveduring a 20 year period. �e investigated charging strategies are slow, fast and induction charging. Depending onhow a ba�ery is charged, di�erent lifetimes may be obtained which is why these strategies are investigated. �eLCC analysis includes and discusses the investment cost, preventive maintenance cost, corrective maintenance costand the residual value. �e aging of the LIB is examined using a ba�ery block in Simulink/MATLAB. �e ba�erymodel and LCC analysis is applied on a mail truck at Arlanda airport and uses therefore inputs from the mail truckto model for example the discharging pa�ern.�e results from the Simulink aging model show that depending on which charging strategy that is used, di�erentlifetimes are achieved for the same LIB.�e results also show that the lifetime of the LIB is strongly a�ected by thecharging current and the SOC limits. Induction charging gives the longest lifetime, 9.4 years, while fast charginggives the shortest lifetime, 7.7 years for an ambient temperature of 20

  • Kjellin, Gustav
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    A Case Study Exploring the Most Important Factors in Firm Rebranding2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A growing use of mergers and acquisitions as a growth strategy has led to what is often referred to as “brand accumulation”, describing a situation in which a parent firm finds itself having acquired firms to the extent that the number of brands under management exceeds the capability of the firm. This, coupled with a generational shift in the workforce that has increased the demands on brand equity amongst potential employees, has increased the need for successful firm rebrandings.

    Today, many rebranding efforts fail, and this paper attempts to highlight the most important factors affecting a rebranding initiative, in order to better understand why some of them fail and why some succeed. The study is based on a framework of success and failure factors, extracted from historical as well as contemporary research into the field of firm rebranding These factors are then evaluated through case studies.

    The research goes beyond looking at a rebrand as just the replacement of a firm logotype or graphical guidelines, and puts added focus on the larger brand visions that are often implemented as part of a rebranding. The case studies were performed at four firms from different industries who has gone through a rebranding with varying degrees of success. The interviewees had different roles at their respective firms.

    The entire paper is structured around the frame of reference constructed during the literature review, a summary of which can be found in section 2.3 on pages 27-29. These factors are the underlying basis for answering the research questions.

  • Newaz, Shegufta
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Urban Design.
    Reversing the Iceberg: Making ‘diverse economies’ visible in the context of migration and gender discrimination.2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The term ‘Economy’ is often framed in relation to money, GDP, industries, businesses, waged labor and market etc. This narrow portrayal of economy excludes all the diverse activities and practices that people perform in everyday life as a part of the economy. J.K Gibson- Graham reframes economy in the book ‘Take back the Economy’ by presenting it as an ‘Iceberg’. While the tip of the iceberg is the visible capitalistic economy, the base underneath is formed with wide range of activities, places and people. These activities ranges from household works, bartering, sharing, recycling, self-employments, social co-ops, volunteering, peer to peer production, reproduction to different forms of local transactions and exchanges which takes place within families, neighbors and communities. In spite of seeing economy as a self-regulating machine the authors introduce the concept of ‘diverse economies’ in which people participate and influence economic actions.The predominant focus on capitalistic economy can be seen in the practice of urban design as well. Urban spaces are designed to foster economic growth as higher GDP rather than socio-environmental wellbeing. The insatiable growth has not only depleted the nature but also created power hierarchy and inequalities in different geographical and temporal level. The diverse economies are often undervalued and obscured eventhough it contributes a great deal in socio-environmental wellbeing. Focusing on the diverse economic activities can help to understand the local practices and resources, and can open up the possibility to empower the community.The thesis explores the theory of ‘diverse economies’ in relation to migration and gender discrimination. In the crisis of mass migration, unemployment, constraints in social welfare different forms of diverse economic practices help the society to sustain well. This thesis investigates the area Hovsjö in Södertälje which is often discussed for its unemployment, segregation, unrest and lack of democratic participation. The aim of the project is to make the diverse economies in Hovsjö visible and scale it up to perform collectively for socio-environmental wellbeing.4| reversing the 'icberg' | 5KTH- sustainable urban planning & design

  • Kindahl, Johanna
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    passage, utkiksplats, förhall, ljusrum, nisch, återvändsgränd2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The starting point of the project is an analysis of my own memories of elementary school. By drawing up the school from memory and analyzing selected spaces, I have investigated what I remember about the school building and why. The experience of many of the spaces I remember as exciting was about a discovery. An organization of spatial relationships in relation to direction led to an idea of a spatial structure and orientation based on two intersecting axes. Internal directions in relation to two intersecting axes have been analyzed by Palladios Villa Rotonda and Palazzo Della Torre.


    The directions from the analysis have been put in relation to the directions of the site. The the analysis resulted in two volumes with a passage between. Through the passage, the outer primary axis spans a wall in front of the school towards the road and the forest which constitutes the far border of the schoolyard.


    At the intersection of the axes is an inner courtyard, an vestibule for the buildings and the inner transverse axis. The inner axes provides a spatial structure around which rooms are organized. A pillar system helps to emphasize the directions in the building. A long vestibule surrounded by pillars leads from the entrances by the inner courtyard to the end point of the inner vestibule, a light room that extends through the floors. The northern part for the younger children has a staircase in front of the light room, the staircase recur for the older children in the southern part behind the light room. In connection with corridors and public areas, there are rooms with qualities from the analysis to be discovered.

  • Palladino, Nicoletta
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Nanomaterials for the consolidation of iron-tannate dyed textiles2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Kilegran, Johanna
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Correction of cupping artifacts in localized laboratoryphase-contrast CT2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Eichler, Martina
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Knowledge Management in Product Development Projects in Developing Countries - A Case Study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this master thesis is to contribute to the reduction of knowledge loss and reinvention inside and between organizations pursuing product development projects in developing countries to ensure growth and improved living standards. Investigation and to determination of existing knowledge sharing and knowledge storing practices in several stakeholders of a product development project in Quelimane, Mozambique will be studied. The involved stakeholders are non-profit and governmental organizations and a group of university students. The product development project involved the design and implementation of an anaerobic digester during the spring of 2018. Collaborations between some of the stakeholders started in 2015 and will exceed the project duration. Mixed research methods were used, and open-ended question interviews were conducted for the qualitative data collection. The data was analyzed by coding to find common patterns and relationships. A literature review and desk research were made to obtain detailed information about knowledge management and other related subjects. Results showed that all organizations involved in the product development process experienced at least one barrier to knowledge transfer related to their position as a nonprofit organization pursuing product development in a developing country. The definition of a knowledge management strategy is as important for non-profit organizations as it is for for-profit organizations, but the current methods for choosing a strategy need to be modified in order to fit the overall strategy of such organizations. The implementation of a knowledge management strategy and suitable knowledge management methods and activities could contribute to the reduction of knowledge loss and reinvention inside and between organizations pursuing product development projects in developing countries to ensure growth and improved living standards.

  • Public defence: 2019-04-08 10:00 Kollegiesalen, KTH-huset, Stockholm
    Risseh, Arash Edvin
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Waste-heat Recovery Using Thermoelectricity and Silicon Carbide Power Electronics2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Energy consumption in the world has increased continuously due to a growing population and increased energy consumption per capita. Moreover, the largest part of consumed energy still comes from fossil sources which in 2016 was more than 130 PWh. In order to minimize the greenhouse effect and meet the climate targets, the world's energy consumption must be greatly reduced and the energy also has to be used more efficiently. Due to the low efficiency of internal combustion engines in vehicles, the transport sector is the second largest source of greenhouse gas emissions, responsible for 20 % of the total CO2 emissions in the EU. In this work the electrical arrangement and power conditioning system suitable for waste heat recovery, using thermoelectric energy conversion in heavy duty vehicles, are investigated. Without a proper power conditioning system, the recovered power from a thermoelectric generator (TEG) disappears in form of Joule-losses. High-efficiency inter-leaved step-down converter with 98 % efficiency was developed and tested on a real-scale prototype truck, equipped with two TEGs. In addition, a strategy was required for the connection of thermoelectric modules (TEM) in the TEGs. A TEG may consist of several hundred TEMs and without a suitable connection, the thermal losses can be so high that the net power, recovered by the TEG is insignificant. In the worst case this can lead to an even higher fuel consumption. Moreover, the possibility to employ silicon carbide (SiC) metal oxide semiconductor field-effect transistor (MOSFET), which is a voltage-controlled and normally-OFF device, with high electric field strength, in such a low-voltage application (100-200 V), was investigated. Due to the high blocking voltage and power density, SiC MOSFETs are expected to replace silicon (Si) insulated gate bipolar transistors (IGBTs) in power converters. However, in low-voltage applications where Si MOSFETs are usually used, there have not been any obvious advantages to use SiC MOSFETs as a substitute for Si MOSFETs. Here, it is shown that SiC MOSFETs can advantageously be used in low-voltage applications. SiC MOSFETs have exceptional properties that nevertheless are fully utilized today. The packages of currently available SiC devices are the same as those previously used for Si devices, with moderate electrical and thermal characteristics. This results in slow switching speed, unnecessary losses. A half-bridge planar module using SiC MOSFET bare dies were designed, manufactured and tested. It was shown that a module with the same structure and 8 SiC MOSFETs can be manufactured with ultra-low parasitic inductances. The total switching energy was found to be 4.4 mJ which is approx. 63 % lower than commercially available modules.This thesis can be divided into three parts. In the first part, thermoelectricity is introduced and an introduction of SiC MOSFETs and its applications are given. In the second part, the results of waste heat recovery using TEG and its electrical arrangement in a Scania truck are presented. In this part, also the output power and the efficiency of the converter, using Si and SiC MOSFETs, are discussed. In the final part, the proposed planar power module with SiC MOSFET bare dies, its benefits such as reduced switching losses and double-sided cooling, are presented.

  • Abdo, Nawar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Modularization and evaluation of vehicle’s electrical system2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modularization is a strategy used by many companies, to help them provide their customers with a high variety of customized products efficiently. This is done through the customization of different independent modules, which are connected by standardized interfaces that are shared throughoutthe entire module variety.

    Scania, being one of the large companies that provide modular products, has been successfully improving their modularization concepts for many years, and is one of the most iconic companies when it comes to modularization of buses, trucks and engines. But with the increasing need ofelectronics integrated in the vehicles, it is becoming more and more important to modularize the electrical system.

    There is currently an existing, modularized, product architecture for the electrical system, and Scania wants to know how well modularized it is, as there is no unified way that indicates what is considered to be the better solution.To analyze the current state of the electrical system, a systematic method of modularization was used, which would help answer three important questions: Are the modules well defined? Is there a way to systematically compare alternative solutions? What criteria are more important to focus on?

    Since there is no unified way of modularization, many modularization methods have been created, and each one has been optimized for a certain purpose.

    This project compares three different modularization methods and then uses one of the methods which is deemed to be the preferred method to help provide the answers that the company seeks when investigating the modularity of the electrical system.

    As the electrical system is very complex, and the project has limited amount of resources, it was decided to choose one of the control units as an example, which was the APS (air processing system).

    The literature study showed that the most rewarding method to use was the MFD (Module Function Deployment), as it provides more information about the product and what criteria the company should focus on. It was then decided to use the relevant steps in MFD to analyze the state of the APS as an example of how this method works.

  • Westlund, Johan
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Design and construction of a contactless excitation and response measurement system2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Manufacturing industry works on Overall Equipment Effectiveness (OEE) to increase the yield and speed of machining. A good knowledge of the machine properties is important to increase the speed while still maintaining stable cutting with low tool usage.To make models of the machine is therefore important and in machining a common way to extract the dynamic properties is frequency response measurement. One way is to use an impact hammer to excite the machine tool and measure the response. The problem is that a hammer can only be used on a non running machine. At Manufacturing and Metrology Systems division at KTH (MMS) a test method for contactless excitation has been developed that uses electromagnets to excite the machine tool. By using contactless testing it can be used on rotating machine tools without real cutting in materials. In this thesis a new test system for the contact less testing method has been designed and constructed to test if it is possible to do test on a bigger variety of rotating cutting machine tools. The results for the prototype is presented and evaluated.

  • Jiménez Sánchez, Juan Luis
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lua Programming in HRC Workstation Design2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Close collaboration between human operators and industrial robots is one approach to meet thechallenges of increased global competition and demographic change for manufacturingcompanies in the developed countries. These human-industrial robot collaborative (HRC)assembly systems combine human flexibility, intelligence and tactile sense with robotic speed, endurance and repeatability. However, current personal safety legislation limits the possible collaborative applications that could be implemented in practice, but large research efforts areput in order to enable practical implementation of these future workstations.

    When the limitations of safety legislation are addressed, and the collaborative systems can beimplemented, a need to simulate these systems will rise. Virtual simulations are an importantcomponent in modern production system design and will be demanded in future assembly workstation design. A new existing software is in development that can simulate, visualise and evaluate HRC assembly workstations. The general goal with the simulation software is to design“optimal” workstations, and they enable evaluations of multiple design alternatives to reach this “optimum”. The creation of these design alternatives is challenging today as it demands a lot ofmanual work. The aim of this thesis is to tackle this issue by contributing to the development andimprovement of the simulation software through the programming of scripts in the Lua language. The scripts were developed through an iterative and trial-and-error process, combined with first-hand experience of the author in the usage of the software.

    The resulting scripts enable the user to perform simulations in a swift, efficient, automated and simplified way in comparison to the traditional method, reducing the need of manual work to a minimum. A large amount of simulations can be performed in a short amount of time, even without the need of human interaction.

    In addition, with the results of the simulations as a base, mathematical optimisation techniques have been employed in order to find the optimal HRC design of a case study station. The case study has been conducted at a workstation in a heavy vehicle manufacturer. The results of the case highlight the improvements made to the software by the scripts and how these can be used to efficiently design the HRC workstations of the future.

  • Yao, Yingshan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The influence of niobium content and cooling rate on mechanical properties of grey cast iron2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project mainly investigated how the niobium(Nb) content influences the microstructure and mechanical properties of grey cast iron. Considering the mechanism, the study also analyzes the relationship between microstructure and mechanical properties. Generally, the work is based on 127 test bars/samples from two cylinder heads and three batches of plates, which were studied by measuring tensile strength, microhardness, graphite size, carbide amount and chemistry. The result data has been evaluated with statistical methods.

    The experiments mainly included the preparation of the samples for test and analysis. The mechanical properties in this study are evaluated by the tensile strength of the grey cast iron. Meanwhile, various microscopies were applied to observe how niobium and cooling rate influence the microstructure.

    Finally, from the analysis results, it tells that the niobium does affect the tensile strength of grey cast iron. Higher the niobium content is, higher the tensile strength is. The computed result based on the data also shows niobium’s strong effect. The faster cooling rate will increase the tensile strength and pearlite microhardness of grey cast iron as well. The carbide amount of grey cast iron can be increased by the addition of niobium content.

    Furthermore, some future work needs to be done to explain the unsolved problem in this result. The reasons of why a specific position A-2-d of plates has high values of tensile strength demand more microstructure investigation. For the niobium influence, more experiments and data containing a larger range of niobium content also need to be done to prove the mathematics results in this report.

  • Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Liu, Qingyun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Huang, Bingru
    Würth, Christian
    Resch-Genger, Ute
    Zhan, Qiuqiang
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Liu, Haichun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    On the decay time of upconversion luminescence2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, p. 4959-4969Article in journal (Refereed)
    Abstract [en]

    In this study, we systematically investigate the decay characteristics of upconversion luminescence (UCL) under anti-Stokes excitation through numerical simulations based on rate-equation models. We find that a UCL decay profile generally involves contributions from the sensitizer's excited-state lifetime, energy transfer and cross-relaxation processes. It should thus be regarded as the overall temporal response of the whole upconversion system to the excitation function rather than the intrinsic lifetime of the luminescence emitting state. Only under certain conditions, such as when the effective lifetime of the sensitizer's excited state is significantly shorter than that of the UCL emitting state and of the absence of cross-relaxation processes involving the emitting energy level, the UCL decay time approaches the intrinsic lifetime of the emitting state. Subsequently, Stokes excitation is generally preferred in order to accurately quantify the intrinsic lifetime of the emitting state. However, possible cross-relaxation between doped ions at high doping levels can complicate the decay characteristics of the luminescence and even make the Stokes-excitation approach fail. A strong cross-relaxation process can also account for the power dependence of the decay characteristics of UCL.

  • Barthélemy, Aude
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Exploratory Study on Lower Limb Amputee Patients : Use of IMUs to Monitor the Gait Quality During the Rehabilitation Period2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Specific rehabilitation is a key period for a lower-limb amputee patient. While learning how to walk with a prosthesis, the patient needs to avoid any gait compensations that may lead to future comorbidities. To reach a gait pattern close to the one of a healthy person, objective data may be of great help to complement the experience of the clinician team. By using 6 IMUs located on the feet, shanks and thighs accompanied by 3 accelerometers on the pelvis, sternum and head, data could be recorded during walking exercises of 7 rehabilitation sessions of a patient. To compute the absolute symmetry index of the stance phase duration and the stride duration all over the instrumented sessions, the gait events defining the transitions between gait phases were determined thanks to several algorithms. By first comparing the error obtained in the calculation of the stance phase duration with all tested algorithms as compared to the data from pressure insoles considered as a reference system, the algorithm developed by Trojaniello and collaborators [1] was found to be the most adapted to this situation. Using this algorithm on the data from all sessions highlighted the possibility to detect changes in the symmetry of stance phase duration and stride duration, that are relative to the gait quality. This means that IMUs seem to be able to monitor the progress of a patient during his rehabilitation. Hence, IMUs have proven themselves to be a system of great interest in the analysis of the gait pattern of a lower-limb amputee patient in rehabilitation, by allowing for an embedded measurement of much more parameters than the pressure insoles, whose calibration constituted a real limitation. 

  • Public defence: 2019-04-12 10:00 Q2, Stockholm
    Persson, Linnea
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Autonomous and Cooperative Landings Using Model Predictive Control2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Cooperation is increasingly being applied in the control of interconnected multi-agent systems, and it introduces many benefits. In particular, cooperation can improve the efficiency of many types of missions, and adds flexibility and robustness against external disturbances or unknown obstacles. This thesis investigates cooperative maneuvers for aerial vehicles autonomously landing on moving platforms, and how to safely and robustly perform such landings on a real system subject to a variety of disturbances and physical and computational constraints. Two specific examples are considered: the landing of a fixed-wing drone on top of a moving ground carriage; and the landing of a quadcopter on a boat. The maneuvers are executed in a cooperative manner where both vehicles are allowed to take actions to reach their common objective while avoiding safety based spatial constraints. Applications of such systems can be found in, for example, autonomous deliveries, emergency landings, and search and rescue missions. Particular challenges of cooperative landing maneuvers include the heterogeneous and nonlinear dynamics, the coupled control, the sensitivity to disturbances, and the safety criticality of performing a high-velocity landing maneuver.

    The thesis suggests the design of a cooperative control algorithm for performing autonomous and cooperative landings. The algorithm is based on model predictive control, an optimization-based method where at every sampling instant a finite-horizon optimal control problem is solved. The advantages of applying this control method in this setting arise from its ability to include explicit dynamic equations, constraints, and disturbances directly in the computation of the control inputs. It is shown how the resulting optimization problem of the autonomous landing controller can be decoupled into a horizontal and a vertical sub-problem, a finding which significantly increases the efficiency of the algorithm. The algorithm is derived for two different autonomous landing systems, which are subsequently implemented in realistic simulations and on a drone for real-world flight tests. The results demonstrate both that the controller is practically implementable on real systems with computational limitations, and that the suggested controller can successfully be used to perform the cooperative landing under the influence of external disturbances and under the constraint of various safety requirements.

  • Public defence: 2019-04-11 10:00 F3, Stockholm
    Gasch, Tobias
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Multiphysical analysis methods to predict the ageing and durability of concrete2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With the societal demand for sustainability and the increasing age of infrastructure, a crucial task for the civil engineering community is to improve the durability of concrete structures. This thesis aims to contribute to such development through theoretical studies using mathematical modelling and numerical simulations. During its service life, a concrete structure is subjected to many different actions, ranging from mechanical loads to chemical and physical processes. Hence, a sound modelling strategy requires multiphysics and the inclusion of coupled chemical and physical fields (e.g. temperature, moisture and cement hydration) in addition to methods that describe mechanical integrity of the material. Conditions and phenomena critical for concrete structures at hydropower facilities have been of particular interest to study.

    The thesis presents several mathematical models of various complexity to describe the multiphysical behaviour of concrete using a material point description. A significant focus is on models that describe the mechanical behaviour of concrete where aspects such as ageing, cracking, creep and shrinkage are investigated. For the creep behaviour, a state-of-the-art model based on the Microprestress–Solidification (MPS) theory is reviewed and further developed. The appended papers (III to IV) presents a mathematical framework for the modelling of durability aspects of concrete based on multiphase porous media theory. The governing equations are derived with the Thermodynamically Constrained Averaging Theory (TCAT) as a starting point. It is demonstrated how this framework can be applied to a broad variety of phenomena related to durability; from the casting and hardening of concrete to the long-term absorption of water into air-entrained concrete. The Finite Element Methods (FEM) is used to solve the proposed mathematical models, and their capabilities are verified using experimental data from the literature.

    The main research contribution is the development and evaluation of theoretical models that advance the understanding and improve knowledge of the ageing and durability of concrete and concrete structures. More precisely, it is shown how multiphysical models and the developed multiphase framework can be used to gain insights on the material behaviour of concrete at smaller scales while they are also applicable to structural-scale simulations. During all model development, the efficient solution of structural problems has been fundamental. Through case studies and several examples from the literature, it is exemplified how these models can be used to enhance the performance and thereby increase the durability of concrete structures.

  • Public defence: 2019-04-05 13:00 F3-Lecture Hall, Stockholm
    Gärdebo, Johan
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Environing Technology: Swedish Satellite Remote Sensing in the Making of Environment 1969–20012019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The state-owned Swedish Space Corporation established a satellite remote sensing infrastructure and defined uses for the technology both within and beyond Sweden during the latter part of the twentieth century. This thesis studies Swedish satellite remote sensing as an environing technology – a technology that environs, that produces environments and our perceptions of the environment. This perspective is important in historicising Sweden’s role in developing a technology that now is used both to manage environments on a global scale and to provide an understanding of what the environment is. It is also important to understand these environing activities as motivated by and related to other aims, for example Swedish non-alignment, development aid, and the export of expertise to new markets. I ask two questions. Firstly, how did Swedish satellite remote sensing activities contribute to the making of environment? Secondly, why did the Swedish satellite remote sensing experts conduct these activities?

    Studying environing technologies requires combining the theoretical understandings of history of technology and environmental history and treats technology and environment as outcomes of environing activities. Methodologically, the thesis studies written and oral sources to find activities related to satellite remote sensing that take part in sensing, writing about, or shaping environments. From these activities, new understandings of technology and environment emerge over time.

    The thesis is structured around five empirical chapters: 1) the institutionalisation of remote sensing as part of environmental diplomacy in Sweden, 1969–1978; 2) the establishment and expansion of a French-Swedish remote sensing infrastructure, showcased by sensing the Chernobyl meltdown in 1986; 3) the export of Swedish technoscientific expertise as a form of development aid, 1983–1994; 4) the promotion of satellites as a tool for sustainable development, 1987–1993; and 5) the establishment of an environmental data centre to monitor the European environment as part of managing the expansion of the European Union, 1991–1999.

    Swedish satellite remote sensing experts contributed to numerous international demonstrations that emphasised the technology as a tool for sustainable development of environments on a global scale. These activities beyond Sweden, often through transnational collaborations, were undertaken to establish satellite remote sensing within Sweden. The lack of a long-term strategy for the Swedish government’s space activities forced the technoscientific experts to find ad hoc uses for their technology, of which environmental applications were the most significant.

  • Public defence: 2019-04-12 10:15 F3, Stockholm
    Pereverza, Kateryna
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Steering sustainability transitions? Modular participatory backcasting for strategic planning in the heating and cooling sector2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fostering sustainability transitions in the heating and cooling sector is a necessary and urgent issue. Steering mechanisms can enable coordination of actions by different actors towards common sustainability goals. Previous studies have identified requirements relevant for such steering frameworks, but have not specifically addressed planning in the highly contextual heating and cooling sector. Participatory backcasting (PB) possesses a number of relevant characteristics for use as a planning framework in this sector, but its adaptability and potential impact first need to be addressed.

    This thesis sought to advance strategic planning in the heating and cooling sector by improving the adaptability, transparency and reflexivity of PB processes and extending their impact beyond individuals directly involved, so-called social scales of impact. Key research objectives of the present work were to: (1) develop a strategic planning framework for the heating and cooling sector based on PB and examine its adaptability to local contexts, (2) develop methods for scenario development, selection and analysis to allow for co-informing between modelling and participatory processes within PB-based strategic planning, and (3) identify factors that could influence the social scales of the impact of participatory strategic planning processes.

    Objectives 1 and 2 were pursued in a multiple case study involving transdisciplinary research over one-year PB-based planning processes in Bila Tserkva, Ukraine (Case I) and Niš, Serbia (Case II). The social scales of impact (Objective 3) were studied in a single case – a Swedish project aimed at advancing the practice of long-term planning in regions ‘Region 2050’ (Case III). In all cases, both theoretical and empirical research were conducted.

    The study proposes a novel framework, modular participatory backcasting (mPB), for strategic planning in the heating and cooling sector. The framework integrates principles of modularity, participatory modelling, and transdisciplinarity. The results of mPB implementation in Case I and Case II suggest that the framework has acceptable adaptability to local contexts. Greater reflexivity and transparency in the scenario development, selection and analysis were achieved by developing a morphological method and implementation of participatory modelling approaches. Finally, boundary spanning individuals, collaborations and institutional plurality were identified in Case III as important factors for broadening the social scales of impact of participatory strategic planning processes.

  • Schillinger, Philipp
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. Bosch Center for Artificial Intelligence.
    Bürger, Mathias
    Bosch Center for Artificial Intelligence.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Hierarchical LTL-Task MDPs for Multi-Agent Coordination through Auctioning and Learning2019In: The international journal of robotics research, ISSN 0278-3649, E-ISSN 1741-3176Article in journal (Refereed)
    Abstract [en]

    Given a temporal behavior specification and a team of agents available for execution in a stochastic environment, it is still an open problem how to efficiently decompose and allocate the specification to the agents while coordinating their actions accordingly and while considering long-term performance under uncertain external events. Our proposed framework works towards this goal by constructing a so-called hierachical LTL-Task MDP automatically by formally decomposing a given temporal logic goal specification into a set of smaller MDP planning problems. In order to efficiently find a multi-agent policy in this generated LTL-Task MDP, we combine methods from planning under uncertainty and auction-based task allocation with techniques from reinforcement learning. A particular challenge is to consider uncertainty in the environment, which might require significant additional effort to satisfy the given specification. This is addressed here by a formalism that allows the agents to consider preparation of such possible future reactions instead of updating the set of tasks only after observing an event.

  • Public defence: 2019-04-03 13:00 F3, Stockholm
    Siyal, Shahid Hussain
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic assessment of wind energy for renewable hydrogen production in Sweden2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wind energy deployment has been growing globally. The resource is expected to play an important role in achieving economic and environmental sustainability - depending on its level of availability, economics, and policy.  Sweden has committed to have 20 TWh/year production of onshore wind energy in the national electricity sector by the year 2020. Further, Sweden has a target for a fossil fuel free transport sector by 2030. Local wind energy coupled to electrolysis-derived hydrogen fuel production offers a pathway for achieving both targets. The analysis of wind energy’s potential in this context necessitates a new type of approach, one that captures the complexities of wind turbine siting in relation to the build-up of hydrogen infrastructure, including refueling stations. In this thesis, high-resolution spatial assessments were performed to evaluate wind energy and wind-to-hydrogen energy potentials, including land use restrictions and techno-economic evaluations. The methodology combines analysis with Geographic Information System (GIS) data and the Hybrid Optimization Model for Multiple Energy Resources (HOMER) tool and includes key constraints with the purpose of improving the fidelity of the assessments.

    Overall, significant potentials for wind and hydrogen energy might be harnessed in Sweden. Wind-generated hydrogen can be produced cost-effectively at selected sites along existing roads. After applying a large array of land use restrictions, results show that around 31% of the total land area is viable for wind energy applications in the country. In total, 190 TWh/year wind electricity could be generated in areas within 30 km from the national electricity grid. Moreover, approximately 25580 kton/year of hydrogen fuel could be supplied by installing wind turbines on the viable land area. While considering standalone wind-powered hydrogen refueling stations, the cost of hydrogen lies in the range of 6-10 USD∕kg, depending on wind speed models employed and other factors. Note that this study does not evaluate how these new wind or hydrogen production potentials might be integrated into the energy sector.

  • Backholm, Johan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Urban Redevelopment in Shenzhen, China: Neoliberal Urbanism, Gentrification, and Everyday Life in Baishizhou Urban Village2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Urban redevelopment is increasingly used as a policy tool for economic growth by local governments in Chinese cities, which is taking place amid rapid urbanization and in an expanding globalized economy. Along with the spatial transformation, urban redevelopment often entails socioeconomic change in the form of processes of gentrification, which is propelled by the dominance of neoliberal market-oriented policy and practice in the country. This thesis analyzes the spatial political economy of urban redevelopment in China through a case study on Baishizhou urban village in Shenzhen in south-eastern China. Setting out from the broad concern over urban inequality, socio-spatial segregation, ‘the right to the city’, and sustainability in contemporary critical urban theory, the thesis constructs a theoretical framework involving the concepts of neoliberal urbanism, gentrification, sustainable urban development, as well as ‘bottom-up urbanism’ approaches. Employing this framework, the case study conducts a macro-level city comprehensive plan analysis, a meso-level urban village redevelopment site plan analysis, and micro-level interview study and ethnographic observations of everyday life and space in the urban village. On the basis of this study, the thesis makes the arguments that: Neoliberal urbanism is certainly active in the spatial political economy of urban redevelopment in Shenzhen and China, and is markedly state-led under authoritarian governance structures that encourage increased marketization; The ongoing processes of gentrification in the urban village are intertwined with local and national political systems and social arrangements, and cause stress for the migrant tenants of the urban village, which clearly is not in line with the urban sustainability discourse of the UN’s New Urban Agenda; The tactic responses and individual coping-strategies found in the urban village reveals a condition of both precarity and agency in the everyday lives of the often marginalized poor that inhabit this urban space, which in turn point at emergent alternative urban (re)development trajectories. Moreover, the bottom-up urbanism approach sheds light on both discrepancy and compliance with the dominant top-down redevelopment policy, and is further suggested to inform the production of policy frameworks that can better facilitate local implementation of the New Urban Agenda in China.

  • Hedin, Björn
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Kann, Viggo
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Improving Study Skills by Combining a Study Skill Module and Repeated Reflection Seminars2019In: Education Research International, ISSN 2090-4002, E-ISSN 2090-4010, article id 9739854Article in journal (Refereed)
    Abstract [en]

    If students have a broad spectrum of study skills, learning will likely be positively affected, since they can adapt the way they learn in different situations. Such study skills can be learned in, for example, learning-to-learn courses. Several studies of such courses have been done over the years, but few of these have been carried out in longitudinal naturalistic settings, where the effect has been evaluated over several years in nonexperimental settings. In this paper, we present a novel approach for learning study skills, as a part of a course running over three years. The course starts with a learning-to-learn module, followed by 11 follow-ups that include, among other things, peer discussions about learning strategies with the aim of promoting self-regulated learning. This evaluation shows which study skills the students were most interested in trying, how successful they were in continuing to use the study skills, and which effects the students believed the study skills had after trying them. No significant change was found in how satisfied the students were with their overall study technique immediately after the initial module, but in the long term, 78% of the students believed the course had promoted their ability to analyze and adapt their study habits. We conclude that our approach could be a useful way to get the students to improve their repertoire and use of study skills, and we believe that the students also will improve general self-regulated learning skills.

  • Söderman, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Ahlin Högfeldt, Simon
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Dynamically Controlled Vacuum Level for Vacuum Pad Grippers2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vacuum grippers are widely used in the industry where objects needs to be gripped and moved. There is a need to reduce the consumption of compressed air that is used to create vacuum. This project aims to investigate one method to reduce this. A system where the vacuum level is dynamically controlled is proposed to reduce the compressed air consumption during the lift. The acceleration of the object during the lift is used to calculate the vacuum level required to hold onto the object, ensuring that the vacuum level remains at its minimum value during the lift. A valve system that can control the vacuum level dynamically was designed. This consisted of a stepper motor connected to a valve, which takes readings from a vacuum sensor to form a closed loop system that controls the vacuum level. A Fanuc robot was used to do lifts on certain objects. Acceleration data was gathered from these lifts and used to calculate the necessary vacuum level. This array of vacuum values to be used during the lift was sent to the control system and an external system measured the consumed air during the lift. The comparison in air consumption was done for these dynamic vacuum values and a constant vacuum value which is set to the lowest constant value needed to hold onto the object during the lift. The testing to determine the air consumption was first done using the calculated reference vacuum but without the robot to determine how well the system performed. These comparisons showed that the reduction of compressed air consumption was between 19.5% - 29.0% when testing without the robot. A single test case was chosen for testing with the robot and the air consumption reduction in this case was 11.3%

  • Potter van Loon, Albertine
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Atypical VRE Variability in Power System Planning and Performance: Illustrated by the case studies of Guinea-Bissau and Turkey2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aims to identify and quantify (1) how Typical Meteorological Year (TMY)-based power systems perform when exposed to atypical variability and (2) how TMY-centric power system design differs from full variability design. A simplified least cost power system planning model, including a novel performance analysis formulation, is proposed and tested for Guinea-Bissau and Turkey, covering both main Variable Renewable Energy (VRE) technologies, solar PV and wind turbines. TMY is compared against 24-year timeseries datasets containing hourly resolution solar PV and wind capacity factor (CF) data.

    This study finds that TMY-based power system designs underperform when exposed to atypical variability. Over the entire dataset, foregone VRE generation and additional expenses approximate 36 GWh and 10 million USD for Guinea-Bissau, and 92 GWh and 232,000 million TL for Turkey. Moreover, Turkey faces unmet demand, amounting up to 50 TWh. Likewise, power system design significantly differs when including atypical variability, illustrating how TMY-centric design underestimates non-VRE capacity and overestimates VRE capacity. 

    In the case of Guinea-Bissau, solar contingency was tested in combination with atypical variability, and harvested the complete exclusion of solar PV from the system. This illustrates the effect of factors such as atypical variability and contingency measures on power system design, especially considering the high solar availability in the country combined with low solar PV costs. Moreover, including batteries as spinning reserve providers, is found to reduce overall system costs and under certain circumstances increase the selection of solar PV.

    Besides addressing these two main questions and the additional stability measure study, this document proposes two new data reduction methods to account for both typical and atypical variability, without adding significant computational costs. The first, labelled the ‘incremental year analysis’ was found to be a proxy to estimate the amount of years required to reach an optimal design. The second, ‘power system performance analysis’, in this study reduces the data size at least by half. Moreover, this approach allows power system planners to further reduce the dataset size when including low underperformance tolerance levels and enables the identification of extreme underperforming years. These approaches do not solve the issue and are time intensive. However, they can complement the existing TMY approach by including atypical variability whilst minimizing computational costs.  

    Thereby, this study concludes that atypical variability impacts power system design and performance, and hence should be included in long-term planning methodologies. Concurrently, this research acknowledges the need for solutions that can circumvent the need for additional, often costly computational resources.