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  • Emborg, Mats
    et al.
    LTU.
    Ohlsson, Ulf
    LTU.
    Persson, Martin
    LTU.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Slitbetong som brobeläggning2019In: Betong, no 1, p. 43-46Article in journal (Other (popular science, discussion, etc.))
  • Haghshenas, Navid
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Sabri, Diar
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Sentiment and growth of different news categories on Twitter: A study in Natural Language Processing2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this age of digitalization, people have begun to change their news consumption behavior. More than half the population of the world has internet access and thereby readily available platforms for acquiring and disseminating news. Twitter has evolved into being a staple for news discussions and even transforming into a stable news source provider. This study aims to examine Twitter as a legitimate news media based on certain news categories and how they differ regarding public interest and opinion. The categories are celebrity, crime, economy, politics & global and we examined the relative growth rate and public sentiment for each category during a period of 10 hours before and 14 hours after an event occurring. The results indicate that the political news category had the most public appraise and also the highest public interest. Furthermore, the political news category also had the lowest fluctuation regarding public sentiment. On the other side of the spectrum, the crime category had both the most negative public sentiment and the lowest relative growth rate.

  • Henriksson, Jimmy
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Hultberg, Carl
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Public Sentiment on Twitter and Stock Performance: A Study in Natural Language Processing2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since recent years, the use of non-traditional data sources by hedge funds in order to support investment decisions has increased. One of the data sources which has increased most is social media and it has become popular to analyze the public opinion with help of sentiment analysis in order to predict the performance of a company.

    In order to evaluate the public opinion one need big sets of Twitter data. The Twitter data was collected by streaming the Twitter feed and the stock data was collected from a Bloomberg Terminal. The aim of this study was to examine if there is a correlation between the public opinion of a stock and the stock price, and also what affects this relationship. While such a relationship cannot be established in general, we are able to show that if the data quality is good, there is a high correlation between the public opinion and stock price, and that significant events surrounding the company results in a higher correlation during that period.

  • Ivarsson, Anton
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Stachowicz, Jacob
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Evaluating machine learning methods for detecting sleep arousal2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sleep arousal is a phenomenon that affects the sleep of a large amount of people. The process of predicting and classifying arousal events is done manually with the aid of certified technologists, although some research has been done on automation using Artificial Neural Networks (ANN). This study explored how a Support Vector Machine performed(SVM) compared to an ANN on this task. Polysomnography (PSG) is a sort of sleep study which produces the data that is used in classifying sleep disorders. The PSG-data used in this thesis consists of 13 wave forms sampled at or resampled at 200Hz. There were samples from 994 patients totalling approximately 6.98 1010 data points, processing this amount of data is time consuming and presents a challenge. 2000 points of each signal was used in the construction of the data set used for the models. Extracted features included: Median, Max, Min, Skewness, Kurtosis, Power of EEG-band frequencies and more. Recursive feature elimination was used in order to select the best amount of extracted features. The extracted data set was used to train two ”out of the box” classifiers and due to memory issues the testing had to be split in four batches. When taking the mean of the four tests, the SVM scored ROC AUC of 0,575 and the ANN 0.569 respectively. As the difference in the two results was very modest it was not possible to conclude that either model was better suited for the task at hand. It could however be concluded that SVM can perform as well as ANN on PSG-data. More work has to bee done on feature extraction, feature selection and the tuning of the models for PSG-data to conclude anything else. Future thesis work could include research questions as ”Which features performs best for a SVM in the prediction of Sleep arousals on PSG-data” or ”What feature selection technique performs best for a SVM in the prediction of Sleep arousals on PSG-data”, etc.

  • Rogers, Patrick
    et al.
    RISE CBI, Research Institutes of Sweden AB, Drottning Kristinas väg 26, Stockholm, Sweden.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Gram, Annika
    RISE CBI, Research Institutes of Sweden AB, Drottning Kristinas väg 26, Stockholm, Sweden.
    Selander, Anders
    Cementa AB, Sweden.
    Bulk Hydrophobic Civil Engineering Concrete for Nordic Conditions: Freeze Thaw Action2019Conference paper (Refereed)
    Abstract [en]

    Concrete is a composite building material which long term function can be modified for example by changing the water to cement ratio (w/c) or by adding in other chemical admixtures to change the fresh and hardened properties of the concrete. The overall goal of this study is to reduce the water absorption capacity of the cement paste/microstructure by at least 85 %. This is achieved by using bulk hydrophobic agents in the mixing phase rather than post hardened surface application. Numerous commercial agents and vegetable oils were tested and showed promising results at a dosage equal to 3% of cement weight. This though affected compressive strengths negatively. As these concretes will be exposed to Nordic winter conditions, the concrete should perform well under repeated salt water freezing and thawing. This continued study will show how a selection of these bulk hydrophobic concretes performed during this part of the study. The concrete has a w/c = 0.4 with a cement content (CEM I) of 430 kg/m3.

  • Andersson, Louise
    et al.
    RISE.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Selander, Anders
    Cementa.
    Trägårdh, Jan
    RISE.
    Continuous Preventive Bridge Maintenance in Sweden – Field Experiment on the Effect of Washing on Concrete Bridges2019In: Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures, 2019Conference paper (Refereed)
    Abstract [en]

    Bridges are an important part of the infrastructure. For the bridges to have the longest possible service life with minimum repairs, the maintenance is of great importance. One type of bridge maintenance that is rarely researched is the continuous preventive maintenance. The continuous preventive maintenance consists of removal of vegetation, cleaning of bridge joints and drainage systems as well as high-pressure washing of the structure. The effects of washing is heavily discussed but not properly researched. A study on the effectiveness of washing concrete is therefore being conducted. A field experiment has been initiated where concrete specimens are installed on an edge beam of a road bridge. The specimens are of two recipes where one represents an old bridge with rather high water-cement ratio and the other one represents a new bridge with a low water-cement ratio. 50% of the specimens are washed annually, while the others are not. Each year samples are collected and tested for a chloride profile. The results for the first year of exposure have been determined. They are promising but are still only very preliminary. The effect of washing, if any, will be visible after a longer exposure.

  • Montelius, Lovisa
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Rezkalla, George
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Providing Mass Context to a Pretrained Deep Convolutional Neural Network for Breast Mass Classification2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Breast cancer is one of the most common cancers among women in the world, and the average error rate among radiologists during diagnosis is 30%. Computer-aided medical diagnosis aims to assist doctors by giving them a second opinion, thus decreasing the error rate. Convolutional neural networks (CNNs) have shown to be good for visual detection and recognition tasks, and have been explored in combination with transfer learning. However, the performance of a deep learning model does not only rely on the model itself, but on the nature of the dataset as well

    In breast cancer diagnosis, the area surrounding a mass provides useful context for diagnosis. In this study, we explore providing different amounts of context to the CNN model ResNet50, to see how it affects the model’s performance. We test masses with no additional context, twice the amount of original context and four times the amount of original context, using 10-fold cross-validation with ROC AUC and average precision (AP ) as our metrics. The results suggest that providing additional context does improve the model’s performance. However, giving two and four times the amount of context seems to give similar performance.

  • Petri, Oliver
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Sebek, Fredrik
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A Comparison of the Password-Authenticated Key Exchange Protocols, SRP-6a and PAKE2+2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Privacy is a rising concern globally, and more of our personal information is stored online. It is therefore, important to securely authenticate and encrypt all communication between the client and the server. Password authenticated key-exchange (PAKE) protocols are promising schemes for more secure password authentication on the web. This report looks at both the theoretical and practical aspects of the PAKE protocols, SRP-6a and PAKE2+, from a business perspective. Benchmarks were used to determine the overall performance of both the protocols using latency and memory as metrics. The benchmarked implementations are written in JavaScript. Furthermore, availability of protocol implementations and theoretical security aspects such as crypto primitives were also analyzed. Our results indicate that SRP6-a is likely the more viable alternative for businesses today. Measured latencies ranged from 368 to 521 ms for PAKE2+ and 114 to 230 ms for SRP-6a, depending on the browser. SRP-6a is not only significantly faster than PAKE2+, but it has greater market adoption and maturity, which PAKE2+ lacks in comparison. However, PAKE2+ has a stronger theoretical security footprint, which may make it a strong contender in the future.

  • Almay, Felix
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Strömberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Applicability of Constraint Solving and Simulated Annealing to Real-World Scale University Course Timetabling Problems2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The university course timetabling problem is the problem of creating a schedule for university courses under certain constraints. The decision variant of this optimisation problem is NP-complete. We have researched this problem and implemented the heuristic simulated annealing. This implementation has been compared with respect to time to the constraint solver CPSolver, based on iterative forward search. Our results show that CPSolver scales better for large problem instances. Simulated annealing as implemented by us is thus not suitable in itself for generating valid solutions to this problem on a real-world scale.

  • Chammas, Kristoffer
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Sirak, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS).
    An Evaluation of the Great Deluge Algorithm in Course Timetabling: As Applied to the KTH-Inspired University Course Timetabling Problem2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The University Course Timetabling Problem (UCTP) can be loosely described as assigning events (e.g lectures) to rooms and timeslots in a way that results in a feasible timetable that is optimal according to some custom criteria. The problem has become increasingly relevant as more programs become available in universities. Due to the complexity of UCTP, the problem is usually solved approximately using heuristics.

    The KTH-inspired UCTP is a variant of the UCTP that is adapted to KTH Royal Institute of Technology. However, few heuristics have been implemented for this variant of UCTP. Therefore, this study introduces an implementation of The Great Deluge heuristic to the KTH-inspired UCTP, and compares it to a state-of-the-art solver for KTH-inspired UCTP.

    The Great Deluge implementation was compared against the state-of-the-art KTH-inspired UCTP solver for different time limits. For each time limit, the output timetable quality was recorded over several executions. The comparison was done on two problem instances of varying complexity.

    The results suggest a behavior that varies over time. For larger time limits, GD produced better timetables than the state-of-the-art and the overall quality of timetables was consistent over several executions. For smaller time limits, GD produced worse timetables than the state-of-the-art and the overall quality of timetables was inconsistent over several executions.

    A few potential causes for the improved performance during the later stages of execution were found through further analysis of the results. Perhaps the biggest potential cause was utilizing the greedy behavior obtained during the mid to late stages of execution.

  • Viotti, Paolo Enrico
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Analysis of the US procedure for the fuel consumption and greenhouse gases certification of heavy duty vehicles2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The vehicle sector is facing the biggest revolution of the last 70 years, whose main target is the depletion of emission and a steady decrease of fuel consumption. The focus in this report is the Green House Gas Emissions model (GEM) developed by the United States Environmental Protection Agency (EPA). The model is one of the newest and most complete simulation tool aimed to provide estimation of fuel consumption and CO2 emissions for the US market depending on the input inserted and the type of vehicle chosen. The usage of these tools is expected to increase in the next decades as it presents a more economical solution compared to chassis dynamometer and real driving test. Furthermore, all the environmental agencies that are developing these programs play also a key role in establishing new rules and regulations.

    Scania, as one of the leading manufacturer companies of heavy duty vehicle worldwide, needs to learn about the new certification processes in US to be able to expand in this specific market. The aim of this work is to learn more about the GEM and to validate its results.

    A theoretical review is performed to understand how GEM is working and how each parameter could possibly affect the outcomes. Several parameter variations on a long haulage HDV are performed with the GEM and output results presented. To validate the GEM the European simulation tool VECTO and an internal Scania worksheet for fuel consumption and emissions analysis are used as they were previously validated by means of the chassis dynamometer test. 

    GEM shows very similar results in this comparison with VECTO and the internal Scania worksheet.

    Assessing the reliability of this programme on a larger scale could represent a key aspect for Original Equipment Manufacturers (OEMs) as they could use this simulation tool to easily and rapidly have some fuel economy results solely based on the specifications of the vehicle in analysis.

  • Ruhlmann, Sébastien
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
    The FLARE Suit: A protection against solar radiation in space2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The FLARE Suit is a device that aims to protect astronauts from intense solar radiation when travelling out of the magnetosphere on future Deep Space missions. This suit is an emergency solution against solar particles that, due to their high density, can cause acute radiation sickness and lead to excessive destruction of internal organs (gastro-intestinal system, nervous system, blood forming bone marrow) and eventually to death. These symptoms will be a lot stronger out of the Earth’s magnetosphere, towards the Moon or Mars. For now, the FLARE Suit is being studied in the intra-vehicular environment as a supplement to already existing shielding provided by the spacecraft’s structure, but extra vehicular activities in space and on other planets can be considered. It consists of a bladder-suit that is to be filled with water when needed, the water being already present on any human carrying spacecraft. The suit can be deployed within a few minutes, be very lightweight at launch due to the resource utilization of on-board water, and does not use a lot of material compared to a fully shielded module since it is fitted to the individual human body. Furthermore, water has been shown to provide a decent shielding per mass capability, the third most shielding efficient material after hydrogenated boron nanotubes (H-BNNT) and high-density polyethylene (HDPE). Water could eventually be complemented with salt that shows high neutron blocking efficiency and could help shield from neutrons (present in secondary particles). Finally, it has a fully adaptive multilayered and shape changing design which allows for real-time scenario adaptation depending on the intensity of the solar radiation, the number of astronauts involved, the time frame and the water supplies. Preliminary design of the FLARE suit is show cased and radiation simulations are being performed in a 1D environment within the Columbus module, highlighting a fifty percent reduction in radiation exposure with 3.5 to 4 centimeters of water, depending on the salt content. Afterwards, a 3D environment is being built, however not tested. For this, selection of a relevant 3D human model, construction of the Columbus module and design choices on human morphology have been made. Matlab codes also were written to build and shape the 3D suit on top of the human model, following diverse radiation shielding strategies.

  • Bhattacharyya, Shounak
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Sivaramakrishnan, Suraj
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Parameter Optimisation of EPAS Using CAE2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To keep up with technological as well as logistical challenges of the modern automobile market, major car manufacturing firms have resorted to virtual simulation tools. This enables the development as well as validation of vehicular models much before resources are invested into a new physical prototype.This project focuses on the development of a tool that would help in optimising the handling parameters of a vehicle. This is achieved by creating an optimization routine for tuning the various parameters of the Electronic Power Steering (EPAS). This process is usually done manually, by on-track testing, due to the difficulties in correlating Subjective Assessments (SA) with Objective Metrics (OM). Automating this process would help to reduce the overall research and development time, by providing a baseline tune for the EPAS parameters which could then be finely tweaked by manual track testing.The tool is built by interfacing various software in a multi-objective optimisation environment known as ModeFrontier. The modelling and simulations are performed in IPG CarMaker, with the post processing of the results taken care of by Sympathy for Data. Multiple optimization algorithms were tested to achieve the best optimisation routine. The EPAS parameters, namely the Basic Steering Torque, Active Return and Active Damping, act as the input to the optimization routine. The outputs of the model are the Objective Metrics, which provide a clear indication of the dynamic performance of a component. These metrics are optimized to _t the Steering DNA structure, which uniquely describes the attributes of a vehicle. The final optimised vehicle is manually tested at the track, to determine the real driving feel.

  • Silvén, Jarl
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Generating documentation during compilation of simple programs2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates if automatic generation of documentation might be possible, and attempts to create a tool that performs this through symbolic execution. It parses and analyses a subgroup of C code, with only integers, if-else and basic operations allowed, and attempts to create comments about the code that would aid programmers in understanding said code. One of the obstacles found was the difficulty in efficiently storing variable information. The solution for this was found, as well as improving the format on comments generated. Finally, a new strategy is presented for dealing with while-loops in the future. While not all obstacles were circumvented, the experiment produced documentation different than source code and can be deemed worthy of more attention in the future.

  • Alonso pinar, Alberto
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Aero and vibroacoustical prediction of the noise generated by turbulent boundary layers2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Flow noise is a major noise source in the transportation industry from the automotive up to the aircraft industry. The characterization of the aerodynamic excitations and of the structure transmission is of primary interest in order to improve the passenger and crew comfort. One important component of the flow noise excitation comes from the wall pressure fluctuations induced by the development of turbulent boundary layers around the vehicle.

    This master thesis is focused on the validation of a method to calculate structural vibrations based on aerodynamic data by the comparison with experimental data. The analysis will be done with a flat plate configuration in a wind tunnel. The strategy yields good results and it has been validated: it could be used for more complex problems.

  • Murray, Lawrence
    et al.
    Uppsala University.
    Lundén, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    Kudlicka, Jan
    Uppsala University.
    Broman, David
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    Schön, Thomas
    Delayed Sampling and Automatic Rao-Blackwellization of Probabilistic Programs2018In: Proceeding of the 21st International Conference on Artificial Intelligence and Statistics (AISTATS 2018), PMLR , 2018Conference paper (Refereed)
    Abstract [en]

    We introduce a dynamic mechanism for the solution of analytically-tractable substructure in probabilistic programs, using conjugate priors and affine transformations to reduce variance in Monte Carlo estimators. For inference with Sequential Monte Carlo, this automatically yields improvements such as locally-optimal proposals and Rao–Blackwellization. The mechanism maintains a directed graph alongside the running program that evolves dynamically as operations are triggered upon it. Nodes of the graph represent random variables, edges the analytically-tractable relationships between them. Random variables remain in the graph for as long as possible, to be sampled only when they are used by the program in a way that cannot be resolved analytically. In the meantime, they are conditioned on as many observations as possible. We demonstrate the mechanism with a few pedagogical examples, as well as a linear-nonlinear state-space model with simulated data, and an epidemiological model with real data of a dengue outbreak in Micronesia. In all cases one or more variables are automatically marginalized out to significantly reduce variance in estimates of the marginal likelihood, in the final case facilitating a random-weight or pseudo-marginal-type importance sampler for parameter estimation. We have implemented the approach in Anglican and a new probabilistic programming language called Birch.

  • Bergman, Gustav
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Visualizing time-on-task in second language learning: A case study2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With globally increased migration and mobility between countries, it has become critical for many people to learn to speak a second language. The focus of this study is on adult migrant language learners that are learning a second language of the host country on the side of their working life. This study aims to support learners in their second language acquisition outside classrooms settings. In particular, it explores how the use of a specially designed application aimed at helping learners to keep track on how much time they spend on studying a second language affects their engagement and motivation to continue study the target language. To support migrant learners keeping track of the time spent on language learning activities (e.g., speaking, writing, reading and listening), a web-based application, the TimeTracker App, accessible through users’ mobile device has been developed by the researcher and offered to the learners. Participants in this study used the application for around two weeks. A mixed method approach was employed: data was collected through semi-structured interviews and by extracting log data from the application’s database. Interview data was analysed by means of a conventional content analysis and log data by using descriptive statistics. Overall, the study’s results show that the use of the TimeTracker App enabled the respondents to feel more aware of how much time they spent on their studies, and inspired them to devote more time to study the target language compared to before using the application. The findings suggest that migrant learners become more motivated and engaged in their second language learning when using the application.

  • Huawei, Ren
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Transfer Path Analysis of Wind Noise on a Passenger Car2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Over the last years, due to the development of quieter engines and drivetrains, the importance of addressing the vehicle wind noise problem has significantly increased.In this thesis work, several existing Transfer Path Analysis methods have been applied on an experimental database acquired during a wind tunnel test on a passenger car with the objective of analyzing the distribution of the wind noise sources and their contribution to the target microphones located inside the vehicle. A major challenge for the Transfer Path Analysis (TPA) consists of the high complexity of the aerodynamic sources exciting the structure. Moreover, the existence of multiple incoherent source phenomena, and the presence of distributed coherent source regions of different correlation scales make the analysis very complex.The thesis work provides a solid and comprehensive analysis of the results obtained by different methods. The outcomes can be potentially useful for optimizing the vehicle NVH performance in future practical cases.

  • Lundmark, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Experimental Evaluation of Spray Reduction Technologies2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report concerns the efficiency of a novel spray deflector design. The novel design is analyzed and compared to a bare hull and a bare hull fitted with spray rails by experimental testing in a towing tank. The bespoke hull has a modular design where different inserts can be installed to make the parent hull into a bare hull, spray rail, low speed or high speed deflector. The hulls are analyzed in two environments, calm water and irregular waves, where the hulls are compared in drag resistance, running trim and heave for calm water and in bow and center of gravity accelerations for waves.

    The calm water results show that the deflectors lower the total resistance with up to 25% compared to the bare hull and by over 15% compared to the spray rail configuration, while also affecting the running trim of the hull, raising it by about 1°compared to both spray rail and bare hull. The heave is also affected but not to the same degree, the low speed deflector and the spray rail hull show a similar increase in heave compared to the bare hull as long as the deflector is at its design speed or lower. Because of this change in running position no conclusion about the specific removal of spray resistance on the part of the deflector compared to spray rails can be stated. The deflector design used in these tests change the running trim which has significant influence on the resistance.

    The irregular wave tests indicate that the current deflectors have a small influence on the vertical accelerations compared to the bare hull. The difference is similar to the spray rail setup where the accelerations at center of gravity for both designs show an increase while the spray deflector exhibited lower accelerations in the bow area.

    Several improvements have been stated that would improve the current design for the next series of experiments.

  • Berndtson, Gustav
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Lindström, Ruben
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Learner feedback on robot-led language cafés2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study intends to further investigate the fitness for robot assisted learning in language cafés. Through conducting dialogues with two learners of swedish, moderated by the robot Furhat and later interviewing the participants, the aim is to identify what areas work well and what needs to improve upon with robot assisted learning in general, and Furhat in particular. This study identifies several areas of improvements, and make some possible suggestions for solutions.

  • Ekman, Patrik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Hartmanis, Eric
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Facial activity recognition as predictor for learner engagement of robot-lead language cafes2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden is a country being extra exposed to immigration and, therefore, suffer from a shortage of teachers within second language learning (L2). Other L2 solutions have increased in popularity but require many volunteers. This fact motivated the project CORALL at KTH, Stockholm, which aims to use robot-assisted language learning (RALL) to simulate a language cafe setting. In order to learn, one has to be engaged. This study thereby aims to examine whether the engagement level of students being exposed to RALL can be classified. This is a contribution to the project’s long term goal of being able to automatically adapt the robot to the learners’ engagement levels. The study also aims to analyze the project’s current status, in order to evaluate its future, by examining teachers’ and the CORALL project leader’s responses to a survey, and then utilizing the SWOT framework to draw conclusions. The technical approach is to use the open source toolkit OpenFace to extract facial features from each frame of video recordings of RALL participants. By annotating each frame with one out of four engagement levels, supervised machine learning algorithms are then used to try and estimate students’ engagement. The results from the technical study are deemed inadequate. The models produced, however, were decent at classifying high engagement levels, which could be of use for further investigation. The results from the investigative survey and the SWOT analysis suggested that the internal and external views of RALL align well with the current focal points of the project. The matter of engagement tracking was deemed as an important factor by all parties. While other circumstances could have improved the technical results, important takeaways for future work were discovered.

  • Jin, Emelie
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Johnston, Ella
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Question generation for language café interaction between robot and human: NLP applied in a robot2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Conversational robots can be used in several contexts, one of them being language cafés. This setting demands that the robot in question can converse on many different subjects and move between them smoothly. For this to be possible one needs to generate many questions on a range of subjects and find a way of moving from one subject to another. This work aims to do this by generating questions using a template framework and navigating between them using clustering, a scalable solution which is adapted to language café settings. The general value of language cafés and their role in a language learning process is also discussed.

  • Melander, Gustav
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Wänlund, Robin
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Maskininlärning som medel för att betygsätta samtal med språklärande syfte mellan robot och människa2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Swedish company Furhat Robotic have created a robot called Furhat, which is able to interact with humans in a language café setting. The purpose of the robot led conversation is for the participants to develop their language skills. After the conversation the humans will answer a survey about what they thought about the conversation with Furhat. A question that has arisen from this is if it is possible to predict the survey answers based on just the conversation. The purpose of this paper is to analyze if it is possible to quantify the conversations linked to the survey answers, and by doing so be able to predict the answers in new conversations with a machine learning approach. The data set being used was obtained from an earlier study in Collaborative Robot Assisted Language Learning. The result returned a RMSE that was greater than the variance of the average conversation score which indicates that the model is not very effective. However, it excelled in some predictions trying to give scores to each separate survey answer, indicating that the model could be used for certain question formulations.

  • Carlsson, Fredrik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Öhman, Joey
    KTH, School of Electrical Engineering and Computer Science (EECS).
    AlphaZero to Alpha Hero: A pre-study on Additional Tree Sampling within Self-Play Reinforcement Learning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In self-play reinforcement learning an agent plays games against itself and with the help of hindsight and retrospection improves its policy over time. Using this premise, AlphaZero famously managed to become the strongest known Go, Shogi, and Chess entity by training a deep neural network from data collected solely from self-play. AlphaZero couples this deep neural network with a Monte Carlo Tree Search algorithm that drastically improves the networks initial policy and state evaluation. When training AlphaZero relies on the final outcome of the game for the generation of training labels. By altering the learning target to instead make use of the improved state evaluation acquired after the tree search, the creation of training labels for states exclusively visited by tree search becomes possible. We propose the extension of Additional Tree Sampling that exploits the change of learning target and provide theoretical arguments and counterarguments for the validity of this approach. Further, an empirical analysis is performed on the game Connect Four, which harbors results that justifies the change in learning target. The altered learning target seems to have no negative impact on the final player strength nor on the behavior of the learning algorithm over time. Based on these positive results we encourage further research of Additional Tree Sampling in order to validify or reject the usefulness of this method.

  • Dahlman, Elsa
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Lagrelius, Karin
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A Game of Drones: Cyber Security in UAVs2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As Unmanned Aerial Vehicles (UAVs) are getting more popular and their area of use is expanding rapidly, the security aspect becomes important to investigate. This thesis is a systematic literature review that examines which type of cyber attacks are most common among attacks directed at civilian use UAVs and what consequences they bring. All cyber attacks presented in the report are categorized using the STRIDE threat model, which risk they pose and what equipment is required for the adversary to follow through with the attack. The findings are that Spoofing and Denial of Service attacks are the most common cyber attack types against UAVs and that hijacking and crashing are the most common results of the attacks. No equipment that is difficult to access is required for either of the attack types in most cases, making the result an indicator that the security state for civilian use UAVs today needs improving.

  • Arleklint, Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Memory Measurement and Message Usage Improvement on an Elevator Embedded System2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    All embedded systems are unique, a design that is suitable for one system can rarely be copied over to another. This inherently makes designing embedded systems difficult. The difficulty is only amplified by the uncertainty of the future requirements as it is developed over time. Being able to continuously validate the performance and the reliability is of great importance to be able to ensure fault proof execution.This thesis explores two areas. A method of tracking the static and dynamic memory usage of a system is crucial to ensure correct functionality under all conditions, and that the implemented hardware will suffice. Multiple possible tools, each functioning uniquely, were developed and tested to find the most suitable for measuring the memory usage of the elevator system. Additionally the message usage, i.e. the way the different units within the studied system communicate with each other, was scrutinized for possible performance and reliability enhancements. A study was made for the most optimal communication protocol, and for how the transmissions could be improved upon.The results show that for this specific system, the best way of calculating the memory usage is with a tool developed within this project. Using this tool it was found that none of the modules in the elevator system use more than 30 % of the available memory during execution. The message usage study shows the most optimal protocol is CAN with the ISO 15765-2 upperlevel protocol, which is the one currently in use. However, improvements to the message transmissions are suggested, such as taking full advantage of the CAN protocol and by implementing message buffers on the receiving end.An important conclusion is that just as there is no unique system design that fits all, there is no memory measurement tool or message usage implementation that fits all systems. Each system has to be analyzed to find the most optimal solution for that particular system.

  • Gawell, Anders
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Kallin, Anton
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Teaching software testing in a modern development environment2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    All developers understand the benefits of testing their code to ensure its functionality. Today’s market is moving further towards design principles where testing is a central or driving force during development. This puts a certain pressure on academia to supply these skills to their students.Recently the course II1302 Projects and project methods at the Royal Institute of Technology in Kista made a concerted effort to introduce the students of the course to these modern concepts. This thesis investigates how areas of testing can effectively be introduced to the students in the course, utilizing a tailored example that takes the area of testing into particular consideration and how to automate it via DevOps-tools provided by a cloud-based service. Further, it also makes an attempt to provide additional material to be used for teaching testing in conjunction with the example provided.The case study covers the development of an example application, meant to mirror a typical student project. It also covers how this was used for teaching the students about the testing areas considered. The covered testing areas include unit testing, integration testing and UI testing. With these given testing areas, the application and an associated learning module was developed for each area in question. Relevant standards, strategies and approaches was also identified for each of these areas.The thesis also presents important properties to take into consideration when developing similar examples in the future, based on the experiences obtained during the study. These include needs such as understandable by inexperienced students, applicability outside the course, adherence to established standards, tools that are simple to use and an architectural structure that allows for testing.Some improvements are also recommended: the students would benefit from learning software testing from an early stage of their studies. The content of the learning modules should also be brought to the students earlier in the course, so it can be applied in their projects at an early stage as well.Further research is also recommended to evaluate the suitability of using other cloud-based environments instead, and to evaluate the applicability of the learning modules for students of varying disabilities.

  • Tokarski, Tomasz
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Nanomechanical properties of nanocomposite polymer layer2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Interphase phenomenon gains more and more interest throughout the research community. An interphase is formed between a filler particle and a polymeric matrix, and it may constitute almost the entire volume of a nanocomposite. If the interphase have favorable mechanical properties it will thus result in a nanocomposite with such properties. Therefore, understanding the principles of its formation and properties are crucial in order to design advanced nanocomposites. This thesis focuses on PDMS-carboxylic acid modified latex nanoparticles (PDMS-CML) surface composites investigated by means of Atomic Force Microscopy (AFM). A new sample preparation method was designed and utilized together with the Gel Trapping Technique (GTT). Quantitative Imaging Mode and Contact Mode were utilized in the AFM studies. Topography and nanomechanical properties were investigated and compared for pure PDMS and PDMS containing the nanoparticles. Further, Contact Mode was used to investigate nanoscale wear of the samples in order to elucidate the interactions strength between the nanoparticles and the matrix.

  • He, Xiao
    KTH, School of Electrical Engineering and Computer Science (EECS).
    User interface suitable for credit risk management2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Graphical User Interface, which is known as GUI, is a way for a person to communicate and interact with a system through icons or other visual indicators. A well designed and intuitive user interface is critical to the success of a system since it encourages a natural interaction between a user and a system, thus conveying information more clearly and efficiently to the user.The aim of this study is to design and develop a user interface that is used in a financial technology company in their credit risk assessment process. The current user interface contains a visualization of an individual credit assessment flow together with a lot of data that is generated in the process. Some of the data is not properly visualized, which leads to confusion among end users.In order to optimize the user experience, a user-centered design approach was used combined with a heuristic evaluation. A new user interface was designed and implemented and according to the heuristic evaluation result, the usability was greatly improved. The new interface is able to help the company to visualize their credit risk assessment process in a better way and facilitate credit officers to make credit decisions. The result could also provide insights to other companies or organizations in presenting their data more clearly and effectively.

  • Trinh, Khanh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Adhesive Performance of UV-cured Clearcoat on Galvanized Steel2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A study has been carried out regarding the possibility for application of UV-cured coatings on different pretreated galvanized steel, in coil coating application. In order to address the questions about whether the adhesion will be affected and how, when combining respective coating with a steel substrate. Two types of UV-curable formulations have been applied respectively, acrylate-based free radical formulation and epoxy-based cationic formulation, on five types of steel substrates. In addition, UV-LED was also investigated as an alternative energy source.

    The aim is to explore the curing of the coatings, the surface topology and hydrophilicity, the material and mechanical properties of coatings and coated systems respectively. It was found that the acrylate coating gives a hydrophilic surface while the epoxy coat is hydrophilic but is more hydrophobic than acrylate. The acrylate resin is not compatible with Standard Ti-pretreatment from PO substrates and the curing of epoxy is inhibited by pretreatment primer in PP substrates. Curing using UV-LED is possible and should be investigated further. No comparison could be made between coating systems acrylate and epoxy, regarding the adhesive performance, due to the failure of obtaining the right thickness for the acrylate coating.

     

  • Shriharsha, Swarga
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Development of a method that quantifies the filtration efficiency of soft particles in drop-in fuels2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The global carbon footprint is increasing with course of time. World is moving towards fossil free and reduce the dependency of fossil fuels to meet their daily needs. Transportation industry is the major user of fossil fuels today and major contributor to the CO2 emissions which leads to global warming. Biofuels are promising and sustainable alternative to the fossil fuels. If biofuel is used in its pure form in the vehicles, it asks for engine modifications. Hence, the concept of drop-in fuels are introduced. Drop-in fuels are those fuels in which conventional fossil fuel is blended with biofuel. This blending leads to several advantages like less amount of unburnt hydrocarbons, less toxic and leads to better lubricity of the fuel. On the other hand, in case of blending fossil diesel in biodiesel lead to formation of insoluble organic compounds called as soft particles. These soft particles get accumulated on fuel filter and in turn reduce the amount of fuel entering the engine causing a pressure drop in the flow. This reduction in amount of fuel entering the engine leads to lower engine performance.

    The study conducted here was successful in developing a method to quantify the soft particles in drop-in fuels where B10 was used as test fuel. The earlier phase of the work comprises literature study on the contaminants in biofuels, working of fuel filters and on some chemical analysis techniques. Literature study is followed by series of experiments that guide through to successfully quantify the soft particles. The earlier stage of experiments included, finding a method to synthesize soft particles in a laboratory scale. This was followed by adding soft particles to fuel and making a synthetic test fluid. Analyzing the filter deposit after filtration helped to quantify the soft particles. The chemical analysis techniques like Gas Chromatography and Mass Spectroscopy (GC/MS) and Fourier Transform Infrared Spectroscopy (FTIR) were used for analysis.

  • Quan, Yongyun
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Topology-based Device Self-identification in Wireless Mesh Networks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the context of the Internet of Things (IoT), commissioning is the process of securely adding a new device to a network. It covers many different tasks, including the physical deployment of devices and configuration of parameters. It is network installers who need to manually commission each device one by one with the help of commissioning tools. In practice, the first task for a network installer is to identify each device correctly before configuring it with proper parameters. Individually identifying each device, especially in a large network, is a very time-consuming process. This is also known as the identification problem. This project is going to address the problem.A novel device identification approach is presented in the thesis, and there is no human intervention involved in the identification process. Devices are trying to identify themselves based on predefined rules and given information. The approach is therefore called device self-identification, and it is implemented in two different algorithms. One is the centralized device selfidentification, and the other is the distributed device self-identification. In short, only one device participates in the device identification process in the centralized approach, and in the distributed counterpart, every device is part of the identification process.The results of the implementations show the potential of the new way to identify devices in IoT. Devices in both the centralized approach and the distributed approach are able to identify themselves given necessary information about the network. A detailed discussion regarding the two proposed algorithms and the network information is presented in the thesis.

  • Enerstrand, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Klassificering av kvitton med hjälp av maskininlärning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Machine learning is used in more and more areas. It has the potential to replace many repetitive tasks, or at least simplify them. Document management within financial systems is an area machine learning can help with. A lot of manual input is often needed in different fields by reading invoices or receipts. The goal of the project is to create an application that uses machine learning for the company Centsoft AB. The application should receive OCR-interpreted texts from an image of a receipt and then, with high certainty, be able to determine which category the receipt belongs to. This report aims to show the development of the machine learning model in the application. The report answers the question: "How can receipts be classified using machine learning?".The methodology case study and the research method MoSCoW will be applied during the project. The project also considers the triangle method described by Eklund. Machine learning frameworks are used to evaluate the trained model. The trained model can, with high certainty, interpret receipts it has not encountered before. In order to get a meaningful interpretation, receipts must have the intention of belonging to one of the eight trained categories.The choice of methods suited the project well to answer the question. The application can be further developed and be implemented in the invoice management system. The implementation of the project gives knowledge about how to work with machine learning solutions. In the future, the technology can be applied in several areas.

  • Nordström, Erik
    et al.
    Sweco Energuide AB.
    Krogh, Peter
    Sweco Energuide AB.
    Nilsson, Ola
    Sweco Energuide AB.
    Sjödin, Gunnar
    Vattenregleringsföretagen.
    Stenberg, Rickard
    Vattenregleringsföretagen.
    Hautakoski, Marcus
    Vattenregleringsföretagen.
    Upgrading of the Lossen and Ransaren dams in Sweden2015Conference paper (Refereed)
  • Rosenqvist, Martin
    et al.
    Vattenfall Research & Development, Älvkarleby.
    Nordström, Erik
    Sweco Infrastructure, Gävle, Sweden.
    Hassanzadeh, Manouchehr
    Vattenfall Research & Development, Stockholm.
    Fridh, Katja
    Lund University, Lund, Sweden.
    Observations and investigations of frost damage mechanisms of concrete dams in Sweden2013Conference paper (Refereed)
    Abstract [en]

    The major part of the Swedish hydro power development took place between 1945 and1975. At that point of time, significant progress had been made regarding the use of highquality concrete for hydraulic structures. In spite of the progress made, deterioration ofconcrete due to freezing and thawing is still frequent. Superficial damage at the waterlineand spalling of concrete far below the water level on the upstream face of concrete damshave been observed. Knowledge about the deterioration processes is important in order toimprove the efficiency of maintenance of hydro power plants. Results obtained from twoexperimental studies of frost damage mechanisms are presented in this paper.

  • Nordström, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hassanzadeh, Manouchehr
    Sweco.
    Inblandning av flygaska i vattenbyggnadsbetong2018Report (Other academic)
  • Hasan, A S M Monjurul
    et al.
    Hoq, Md Tanbhir
    Kabir, Ahsan
    Sakib, Taiyeb
    The Cost Factor Analysis of Wind Power Plants-An Economic Perspective2018In: 5th International Conference on Developments in Renewable Energy Technology 2018 (ICDRET’2018), 2018Conference paper (Refereed)
    Abstract [en]

    Renewable energy can help the countries to meet their sustainable development goals. It provides provision of access to clean, secure, reliable and affordable energy. Renewable energy has gone mainstream, accounting for the majority of capacity additions in power generation today. Today wind power plant technologies are experiencing renaissance and the wind turbine promises to be an important alternative to fossil fuels in the future. Therefore, cost factors of the wind power plants have been analyzed in this paper in perspective of Sweden and Germany. The capital expenditure costs include material and labour cost for civil work, turbine installation and electrical connection. The most significant part among all is turbine installation. The revenue depends on the market price and financial support through government strategies and regulations. The analysis is based on a range of data sources of cost indicators – capital expenditure, operational expenditure, levelised cost of electricity and revenue. This paper is not a detailed financial analysis of project economics rather it provides simple and reliable information which can be used to evaluate the costs of different wind power projects.

  • Hoq, Md Tanbhir
    et al.
    Hasan, ASM Monjurul
    Kabir, Md Ahsan
    Sakib, Taiyeb Hasan
    Renewable energy potential assessment for electricity production in Hatiya Island Bangladesh2018In: 5th International Conference on Developments in Renewable Energy Technology (ICDRET’18), 2018Conference paper (Refereed)
    Abstract [en]

    Hatiya Island in Bangladesh is an off grid remote locality. Despite being only twenty kilometers away from shore the island lacks any electricity grid connection. There has been governmental initiative for establishing a hybrid power plant in the island but that project was not realized. Thus there is a need for further investigation to plan electricity production in the island to sustain its energy requirements and development. As a part of a project to identify, model and optimize electricity production in the island this paper investigates the renewable energy potential for power generation in the island. It is found that the island has substantial potential for solar and biomass power generation and further investigation is required to understand the reality of wind power generation. Simulation with HOMER is conducted to outline possible energy mix for the island. There is no data found for electric energy requirement of the island and therefore further research is suggested to mitigate the discrepancies found in the existing literature build a concrete model for calculating optimum energy mix.

  • Public defence: 2019-10-24 10:00 Kollegiesalen, Stockholm
    Ruggieri, Federica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Transaminase Biocatalysis: Applications and Fundamental Studies2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biocatalysis is the branch of science at the intersection between chemistry and biology and specifcally dedicated to the application of natural evolvable catalysts, i.e. enzymes, in human-designed chemical processes. Among the array of promising biocatalysts, transaminases (EC 2.6.1.x) are possibly one of the enzyme classes with the largest unrealized potential. Fast inactivation, poor acceptance towards unnatural substrates and limited tolerance to cosolvents are some of the main factors hampering their implementation in chemical synthesis. In the present thesis work advances in both transaminase application and molecular understanding are presented. Indeed, these two topics are deeply interconnected, as a better molecular understanding is expected to ease the generation of novel enzyme variants suitable for new desired applications.

    From the application perspective, the design of an effective one-pot transaminase-based racemization system offers new possibilities for the design of fully biocatalytic dynamic kinetic resolutions of valuable chiral amines. Similarly, the successful structure-guided redesign of the small substrate binding pocket of the Chromobacterium violaceum (S)-selective transaminase (Cv-TA) granted access to a new enzyme variant active on semi-preparative scale towards the unnatural substrate 1,2-diphenylethylamine.

    From the molecular understanding perspective, the combination of crystallographic and computational techniques led to the formulation of a dimer dissociation model valid for Cv-TA and possibly for other enzymes belonging to the same fold type. This model, which aided the improvement of the Cv-TA stability by structure-based engineering, will hopefully enable similar results in other structurally related enzymes.

  • Nordström, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hassanzadeh, Manouchehr
    Sweco.
    Ekström, Tomas
    ÅF.
    Janz, Mårten
    ÅF.
    Guideline for structural safety in cracked concrete dams2019In: Sustainable and safe dams around the world : proceedings of the ICOLD 2019 symposium, (ICOLD 2019), June 9-14, 2019, Ottawa, Canada = Un monde de barrages durables et sécuritaires : publications du symposium CIGB 2019, Juin 9-14, 2019, Ottawa, Canada, CRC Press, 2019, p. 1681-1696Conference paper (Refereed)
    Abstract [en]

    Several concrete dams show cracking, and their condition and remaining service

    life must be determined. Assessment and service life prediction of cracked dams should include an investigation to determine the cause and consequences of cracks. Cracks can be caused by different mechanisms, which also may act together. Some mechanisms act during a short period of time, e.g. in the beginning after construction, while other mechanisms may influence the dam during the whole service-life. Therefore, it is important to combine observations, measurements, laboratory tests and theoretical analyses investigating the causes of the cracks, their future development and the influence they may have on the performance of the dam. Lessons learned and knowledge concerning crack propagation in concrete and rock, general material engineering, durability concerns caused by cracks, structural analysis issues connected to cracks, field measurements and design of remedial measures has been compiled in a Swedish guideline. The guideline highlights issues that should be looked for in inspections and contains a methodology to determine the residual strength and serviceability of cracked concrete dams and how to review dam safety criteria’s. This in turn will provide the dam owner with a better means to manage and prioritize rehabilitation and maintenance work.

  • Abbasiverki, Roghayeh
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ahmed, Lamis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nordström, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Sweco.
    Analysis of load and response on large hydropower draft tube structures2019Report (Refereed)
    Abstract [en]

    In a reaction turbine, the runner outlet is connected to a diffuser which is called the draft tube. Large hydropower units with large effect and large discharge normally require large dimensions on the waterways. In some large-scale facilities, the total width of the draft tube is so large there is a need for a supporting centre wall in the draft tube. In the Swedish hydropower business, there are several cases where damages or cracks have been reported in the contact between the roof and the supporting centre wall. The most likely reason for cracking between wall and roof is when refilling the draft tube after it has been drained for inspection. A too quick refilling will give an upwards lifting force on the roof that can be larger than the capacity in the joint. There are still uncertainties regarding the risk for a long-term scenario where any operational pattern could give continued crack propagation.

    Vattenfall Hydropower has made an installation with pressure and strain sensors in one of their facilities with a centre wall supported draft tube and a cavity between the roof and the rock cavern. The aim of the project is to get a better understanding on the behaviour of the roof and centre wall during different operational events by evaluating measurements from the draft tube and investigating possible load cases that can create continued crack propagation during operation. In this regard, in this project, the measurements are analysed to discover the different operational patterns and the corresponding effect on applied pressure on draft tube central wall and roof and structure response. A simplified finite element model of the draft tube is demonstrated and the response from the structure due to extracted load patterns is compared with the measurements.

    One-year measurements of the unit operation indicated that unit operates over the whole range with many start/stops. Three major types of operation were: normal operation (working in daytime and downtime at night), continuous operation with no stop and start-stop events with sharp start/stop in the morning and afternoon. The analysis of pressure measurements indicated that the fluid motion in the straight diffuser is turbulent and possibly influenced by vortex formation under the runner. Therefore, the pressure on the right side of the central wall was higher than on the left side.

    The quality of the strain measurements showed to be of insufficient quality and lack of information regarding the set-up. This has given questions on the possibility to get reliable results in the evaluation. Nevertheless, an evaluation has been performed. The evaluation of strain measurements demonstrated higher strain values at the upstream side of the central wall and roof. Moreover, the strain on underside of the roof was higher than on the central wall. Sudden fluctuation during continuous operation and sequence of start/stop were the cases that in long-term may cause damage to the structure due to fatigue problems. The results from finite element model indicated high tensile strength at the upstream side of the straight diffuser, in contact between the roof and the central wall where a crack has been detected in the real structure.

  • Pathanatecha, Worabhorn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    A Study of Various Parameters Affecting Adhesion of Coatings to Metal Substrates2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The adhesion of coatings is of high importance in the coating industry and a more thorough understanding of adhesion behavior is required. In this thesis work, seven parameters affecting adhesion of silane-modified poly(urethane urea) (PUSi) coatings on pretreated steel and aluminum substrates were studied. These parameters include substrate type, dry film thickness (20-30 and 60-70 μm), solid content (40, 60, and 70 wt%), resin ratio between two different types of PUSi (PUSi-A: PUSi-B = 70:30, 50:50, and 30:70 wt ratio), crosslinking density, additive, and curing condition. The different pretreatments of substrates include solvent wiping, sandblasting, phosphating, and galvanizing. A commercial paint product (‘yellow topcoat’) was used as a reference for the study of substrates and additives. Several formulations of clearcoat, prepared from the same PUSi resins as the commercial paint product, were mainly used in every experiment. The obtained coatings were tested for their adhesion properties using cross hatch adhesion test, bending test, and humidity resistance test. The film hardness and thermo-mechanical properties were evaluated with König pendulum hardness test and Dynamic Mechanical Analysis (DMA), respectively. Surface energies of all substrates were analyzed with Contact Angle Measurement (CAM). The PUSi-A and PUSi-B resins used in the coating formulations were characterized with Differential Scanning Calorimetry (DSC), Size-Exclusion Chromatography (SEC), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed a correlation between poor adhesion properties and the relatively low surface energies of some substrates, namely cold-rolled steel (CRS), industrial ACE aluminum, and standard Q aluminum. The use of silane-functional crosslinking agent and silane adhesion promoters in the coatings has greatly enhanced adhesion. The increase in film hardness via increased crosslinking density also did not hinder the adhesion due to the presence of silane groups in the crosslinker. Additionally, increased time and temperature during curing showed positive effects. However, the variation of resin ratio, solid content, and film thickness did not offer significant adhesion improvement in this study.

  • Lindblom, Marcus
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Åhlin, Robin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Medical counselling via video using WebRTC: User interface and user experience design2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    CareLigo is a medical technology company that supplies heart failure patients with a home-based care solution called OPTILOGG. OPTILOGG helps patients to keep track of their symptoms, provides medication instructions and educates them about their illness. CareLigo requested an expansion of OPTILOGG which would allow patients to talk to care providers via video communication.

    This thesis describes the creation of this video communication solution and how this can be done in the best way for both patients and caregivers. Based on literature studies on human-computer interaction, user interface (UI) and user experience (UX) design, a standalone Android application was developed for care providers as well as an extension in OPTILOGG taking into account that the users of OPTILOGG are often elderly with multimorbidity. Three accessibility aids were added to the extension of the OPTILOGG Android application in addition to the video solution. The first helping addition was a touch area expansion for buttons. The second aid was a screen reader feature that vocally describes objects the user clicks on. The third tool was a speech recognition feature that allowed patients to navigate in OPTILOGG with voice. The video communication between the standalone care provider application and OPTILOGG was based on WebRTC and was developed using a software development kit from a cloud communications provider called Sinch.

  • Lindgren, Erik
    et al.
    Högskolan Väst.
    Malmström, Mikael
    Swerim AB.
    Annika, Strondl
    Swerim AB.
    Anton, Jansson
    Swerim AB.
    Nondestructive Evaluation with Laser Ultrasound of Powder Bed Fusion Printed Metal2019Conference paper (Refereed)
    Abstract [en]

    Many of the main advantages of 3D printing metal components, for example the possibility to manufacture parts of high geometric complexity in small series, typically make the nondestructive quality control difficult and resource intense. A number of published studies have proposed in-process nondestructive evaluation of the printed material, as it is built layer by layer, as a possible general approach solution to this difficulty. Previous studies have also indicated that the non-contact nondestructive testing method laser ultrasound might be an applicable method to conduct such an in-process nondestructive evaluation of 3D printed parts. Potential pros of such an ultrasonic based evaluation, as compared to more process monitoring like approaches (e.g. acoustic emission from the printing process) would for example be increased defect characterization capabilities.In this work laser ultrasonic nondestructive evaluation of both electron beam and laser beam powder bed fusion printed metal is demonstrated. Nickel-base and Stainless Steel samples are evaluated both from a machined surface and, in order to simulate the in-process setup, from the as-printed top surface.The laser ultrasonic evaluation results are then compared to results from other material characterization methods, such as light optical microscopy and X-ray inspection. Designed artificial defects as well as process material anomalies could be detected with the proposed laser ultrasonic evaluation. In some cases material defects could be detected also when the laser ultrasonic evaluation was performed from the as-printed top surface.Our results are similar to other studies that have been reported on the subject: laser ultrasound can be utilized to detect material anomalies of interest in powder bed fusion printed metal material. Further research is required in order to better understand and improve the capability and reliability of the nondestructive evaluation method.

  • Malmström, Mikael
    et al.
    Swerim AB.
    Jansson, Jansson
    Swerim AB.
    Lindell, David
    Swerim AB.
    Brask, Johannes
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Comparative study of structures in annealed 304 stainless steel using laser-ultrasonics (LUS) in combination with EBSD and XRD2019Conference paper (Refereed)
    Abstract [en]

    The material investigated was 304 (18/8) stainless steel that had been rolled with 70% at 700°C reduction to a final thickness of 2.9 mm. This warm rolling was chosen to avoid complications due to the formation of deformation martensite at room temperature. A 2.9x30x170 mm strip of the steel was then annealed in a controlled temperature gradient ranging from room temperature up to 1100°C so that all possible microstructural stages were represented, comprising recovery, recrystallisation and grain growth as well as their related texture changes. All measurements were made after cooling the specimen down to room temperature.Grain sizes were measured by LUS using the b-parameter analysis of attenuation data. In addition, the newly developed method for scanning the generating laser was applied to show the influence of texture on the anisotropy of wave velocities. Thus, both grain size and texture were continuously monitored along the length of the gradient annealed specimen.X-ray diffraction (XRD) was applied at various positions such that recovery and recrystallisation could be quantified using peak breadth measurements. In addition, microstructures and textures were determined using electron back-scattering diffraction (EBSD) at several locations corresponding to different annealing temperatures.All the observations were congruent in defining the location where primary recrystallisation had taken place over a relatively short distance on the specimen. The XRD line breadths dropped sharply and then remained constant after higher temperatures. However, the LUS grain sizes which also showed a sharp decrease then increased continuously as grain growth progressed, in good agreement with the EBSD observations. The anisotropic wave velocity results confirmed a significant change in the texture corresponding to recrystallisation despite the fact that EBSD showed that there was, in fact, only a modest weakening. A sensitive parameter defining recrystallisation was found to be the Poisson’s ratio which fell sharply and then increased very gradually up to the highest temperatures. This is interpreted as being due to the textural change during recrystallisation, followed by some sharpening of the annealing texture during subsequent grain growth.

  • Wen, Yuming
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Study of the Performance of Peat Moss Pyrolysis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Peat moss, also called sphagnum, has become a big problem in many countries such as China and Sweden due to its high green-house gas emission from chemical and biological degradation. In this work, the performance of peat moss pyrolysis has been studied, to investigate the potential of application of peat moss pyrolysis on fuel and chemical production. Thermalgravimetric analysis (TGA), differential thermal analysis (DTA), and pyrolysis experiments in a bench-scale reactor have been conducted. Kinetic parameters were calculated based on the results of TG and DTG by Kissinger-Akahira-Sunose (KAS) method and Coats-Redfern method. 450, 500, 550, 600 °C were chosen as the pyrolytic peak temperatures and four phases of products (char, aqueous phase, tar, and gas) were collected. It was found that the peat moss pyrolysis from room temperature to 900 °C could be classified as a six stages reaction. Stage 1 to stage 5 were estimated to be the results of the removal or decomposition of moisture content, hemicellulose, cellulose, lignin, and CaCO3, respectively. The results of activation energies calculated by Coats-Redfern method revealed that, when the heating rate different from 10, 15, and 20 °C/min: stage 3 had the activation energy of 276389, 262587, and 239049 J/mol; stage 4 had the activation energy of 252851, 248918, and 307427 J/mol; stage 5 had the activation energy of 1108268, 814402, and 857437 J/mol, respectively. When the peak pyrolytic temperature raised from 450 to 600 °C: the production of char would decrease; the 500 °C one had the highest production of tar; the aqueous phase produced had the highest TAN value at 500 °C.

  • Frid, Emma
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Accessible Digital Musical Instruments: A Review of Musical Interfaces in Inclusive Music Practice2019In: Multimodal Technologies and Interaction, E-ISSN 2414-4088, Vol. 3, no 3, article id 57Article in journal (Refereed)
    Abstract [en]

    Current advancements in music technology enable the creation of customized Digital Musical Instruments (DMIs). This paper presents a systematic review of Accessible Digital Musical Instruments (ADMIs) in inclusive music practice. History of research concerned with facilitating inclusion in music-making is outlined, and current state of developments and trends in the field are discussed. Although the use of music technology in music therapy contexts has attracted more attention in recent years, the topic has been relatively unexplored in Computer Music literature. This review investigates a total of 113 publications focusing on ADMIs. Based on the 83 instruments in this dataset, ten control interface types were identified: tangible controllers, touchless controllers, Brain–Computer Music Interfaces (BCMIs), adapted instruments, wearable controllers or prosthetic devices, mouth-operated controllers, audio controllers, gaze controllers, touchscreen controllers and mouse-controlled interfaces. The majority of the AMDIs were tangible or physical controllers. Although the haptic modality could potentially play an important role in musical interaction for many user groups, relatively few of the ADMIs (15.6%) incorporated vibrotactile feedback. Aspects judged to be important for successful ADMI design were instrument adaptability and customization, user participation, iterative prototyping, and interdisciplinary development teams.

  • Ghazi, Sarem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Muruganandam, Dhinesh Kumar
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Assembly Line Design for Electric Driven Vehicles (or Powertrain): Investigation of using Smart Manufacturing Technologies in Concept Designs for Assembly Lines2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the rise of smart manufacturing technologies and a shift towards a new industrial revolution, brings forth many new challenges, one of which is how to adapt and integrate these technologies into existing assembly lines. Scania CV AB has joined this race and, with the help of smart manufacturing solutions, works on increasing efficiency amongst its assembly lines. This thesis is aimed at creating concept designs using different smart manufacturing technologies in the assembly line of a pedal car, to evaluate and adapt the concept suited for a real assembly line. The thesis starts with studying the different smart manufacturing technologies to better understand them and the scientific methods used. This follows up with the methodology where several scientific methods such as morphological matrix and weight based decision making matrix are used to generate and evaluate different concept designs. This is followed by a qualitative analysis that helps in selecting the concept design that best suits the needs of the assembly line under consideration. The different concepts are visualized and the evaluation based on different parameters are discussed. This thesis lays a foundation to realize that an aggregate of an optimized process plan, a continuous improvement strategy and the right use of smart manufacturing technologies contributes to the productivity of the assembly line in the long run.

  • Englesson, Erik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Azizpour, Hossein
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Efficient Evaluation-Time Uncertainty Estimation by Improved Distillation2019Conference paper (Refereed)
  • Baldassarre, Federico
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Azizpour, Hossein
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Explainability Techniques for Graph Convolutional Networks2019Conference paper (Refereed)
    Abstract [en]

    Graph Networks are used to make decisions in potentially complex scenarios but it is usually not obvious how or why they made them. In this work, we study the explainability of Graph Network decisions using two main classes of techniques, gradient-based and decomposition-based, on a toy dataset and a chemistry task. Our study sets the ground for future development as well as application to real-world problems.