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  • Katycheva, Anna
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    From Brownfields to Green Infrastructure: A resilience thinking approach to brownfield transformation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Brownfields have the potential to be transformed to offer green infrastructure to cities and bottom up environmental stewardship approaches can be a creative and dynamic way of providing much needed ecosystem services to the urban environment. The following study explores how the transformation of a contaminated site to a community garden in Stockholm can contribute to providing ecosystem services and improving general resilience. Through aqualitative method including literature review, interviews and observations; the results showed elements contributing to resilience including an increase in the diversity of the urban landscape, the creation of a space for social connections, and a gateway to sharing knowledge and creating polycentricity in natural resource management.

  • Shi, Jiajun
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Yin, Wenjie
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Du, Yipai
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Folkesson, John
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, Perception and Learning, RPL.
    Automated Underwater Pipeline Damage Detection using Neural Nets2019Conference paper (Refereed)
    Abstract [en]

    Pipeline inspection is a very human intensive taskand automation could improve efficiencies significantly. We propose a system that could allow an autonomous underwater vehicle (AUV), to detect pipeline damage in a stream of images.Our classifiers were based on transfer learning from pre-trained convolutional neural networks (CNN). This allows us to achieve good results despite relatively few training examples of damage. We test the approach using data from an actual pipeline inspection.

  • Stjernquist Desatnik, Marie
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Energy Access for the Most Vulnerable Groups: A Study on the Long-Term Effects of Energy Access in a Refugee Camp Context with Inclusion of the Host Community2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The UN 2030 Agenda for Sustainable Development outlines 17 goals to end poverty and ensure the right to development for everyone. Previous research has found that 2/3 of the goals partly depend their success upon whether SDG 7 Ensure access to sustainable, affordable and modern energy for all is achieved or not. Given that the Agenda targets everyone it cannot be achieved without reaching the most vulnerable groups, among these groups are migrants, refugees and those internally displaced. Low- and middle-income countries host 84% of this group. Almost 30% of refugees live in managed camp settings and it has been estimated that 80% of these have minimal or no access to electricity. For cooking needs a majority depend on traditional cooking with firewood and charcoal. In many cases this spurs tensions and at times conflict with the local host community, -who often also heavily depend on this resource. On the national level energy is often seen as part of the long-term development planning and as refugee camps and humanitarian setting are recognized as temporary by the host country this creates a vacuum. However, the reality is that 2/3 of all refugees are in protracted refugee situations and the average lifespan of a camp is 17 years. This thesis studied the links between energy and the nexus of environment, social stability and economy in a refugee camp context, and outlined how different energy systems could impact the situations for both groups and also for the relationship between these groups. This was done using the Long-range Energy Alternative Planning systems (LEAP) and by creating a Multi Criteria Analysis template. The case study of Kakuma camp in Turkana County in the North of Kenya was used. The results showed that there are positive and negative aspects related to all energy systems studied here (for household energy access both for electricity and cooking). A refugee camp is a highly complex setting, operating both under the authority of local actors and of international humanitarian actors. For electricity access, Solar Home Systems was found to be a good choice due to the fast deployment time and the low level of infrastructure needed. For already existing households PV Hybrid mini-grids are to be recommended. For cooking options, it was found that for Turkana county, rather than just focusing on GHG emissions it is vital to mitigate deforestation seeing the county’s vulnerability to land-use change. However, changing from firewood and charcoal would affect the livelihood of the host community who depends on the income deriving from the charcoal business. This highlights some of the complexity of the study and the importance of knowing the local context before carrying out energy interventions in a refugee camp and surrounding area. The author’s conclusion is that this methodology could be implemented on any camp setting seeing that modern and clean energy access poses many benefits to people across the world, whether in an urban, rural or refugee camp setting. The thesis found that the main barriers identified for electricity projects of scale are the current funding structure of humanitarian organizations and national government’s attitude towards the camp.

  • Persson, Jennifer
    KTH, School of Industrial Engineering and Management (ITM).
    Stakeholder & Developer Communication Powered by Product Owners2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to investigate the challenges and opportunities in the communication between software developers and their stakeholders, as well as the impact that the product owners have on the communication. The research was conducted using a case study approach, and data was mainly collected through observations andinterviews with product owners and software developers at the case company Kry. The findings show that the challenges in communication are the technical language of software developers, difficulty for stakeholders to understand the software development process and difficulty for developers to understand the underlying context of a feature request. The opportunities in their communication are that the developers can better understand the reasons of a request and thus feel more engaged in the product and more satisfied towards the company; Good communication can cut development time and cost. The product owner is shown to be almost irreplaceable due to the large impact that they have. They become translators between the developers and stakeholders, enabling them to communicate better. Furthermore, they are the main point of contact for the stakeholders, thus allowing the developers to focus more on doing development work. However, this might sometimes result in that the developers get involved too late in the process, making changes costly when they discover something faulty. As a conclusion, the communication between stakeholders and developers powered by product owners greatly enhance the possibility to build good, maintainable software and lead to a more sustainable work environment for all involved.

  • Engström, Pontus
    KTH, School of Industrial Engineering and Management (ITM).
    Exploring the non-technical challenges: A case study of identity and access management projects2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The implementation of an Identity and Access Management (IAM) solution is a complex process to manage, consuming multiple years and involves organizational changes. In its nature, several challenges tend to appear to different stakeholders involved in the process. However, prior research has mainly addressed the technical components of an IAM-solution, hence the technical challenges that emerge during development and implementation. Therefore, the non-technical challenges of the IAM-project work and the challenges that constitute the client implementation are understudied. The purpose of this thesis is to visualize the challenges that emerge when an IAM-solution is implemented. In addition, the challenges when organizational changes occur. The empirical data is conducted through a series of semi-structured interviews with individuals in the IAM line of business. In addition, secondary data is gathered through the review of papers and reports in Information Systems (IS) and Information Technology (IT) projects and outsourcing projects, as well from a non-academical organization with in-depth knowledge of IAM implementations. A qualitative case study of IAM implementations was conducted to investigate the studied complex phenomenon. The findings display the challenges of Insight, Communication, and Endurance (ICE), which tend to be obstacles for all stakeholders involved. Additionally, the organizational changes describe three further challenges of Anchoring, Communication, and Vision (ACV). These challenges mainly appear in client changes, which IAM implementations initiate. The thesis display connections and incoherent with prior research on IS/IT-projects and IAM-projects. In addition, newly uncovered aspects that contribute to research areas are highlighted. The thesis is summarized with some implications and possibilities for future research.

  • Axelsson, Alice
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Flexible high chair for home environments: Development of a first prototype solution that facilitate storage and transportation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When small children eat, they usually sit in a high chair to reach the same table level as the adults. There are many different kinds of high chairs on the market with different functionalities, such as high chairs that grows with the child and high chairs that are attached to ordinary chairs. Some households have more than one alternative, just because their ordinary high chair isn’t easy to transport. Furthermore, due to compact living situations, it can be advantageously having the possibility of easily store it away when the high chair isn’t in use.

    Therefore, the purpose with this project was to develop a first prototype proposal of a flexible high chair, that easily can be stored and transported, but still fit within home environments. The project presented in this report is a master thesis project conducted during spring 2019 within the master program Industrial Design Engineering at the Royal Institute of technology, in conjunction with Svensk Konstruktionstjänst and their client Twistshake.

    The project followed an iterative product development process. It included research to obtain deeper understandings of the users, analysis of the results and determination of project direction, concept generation and concept selection. A mock-up and prototype were made to test ideas. Based on this, the final result of the project was developed. In the project, two of UN’s 17 global sustainable development goals were taken into consideration: number 3, good health and well-being and number 12, responsible consumption and production.

    The result of the project is a first prototype solution of a flexible high chair. It is a high chair that grow with the child from around 6 months to 4 years old. It is developed to facilitate the child’s development and by that offer long user time, which also favour the environment. When not in use, the high chair can easily be folded into a flat package for storage or transportation.

    As the project was limited to 20 full time weeks, further work needs to be done before reaching a real product. The first prototype and suggestions of further work has been discussed.

  • Löfgren, Kim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Hannula Virving, Lisa
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Avstämningsmetod för installatörer kopplat till slutkostnadsprognos2019Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    This master thesis has mainly been built on interviews with interested parties at Arcona and the installer, Nymans Elektriska, since it was decided to limit the study only to the project Glömstaskolan. The aim of the study is that Arcona should be able to report a more accurate final cost forecast to the client regarding the installer and to simplify the reconciliation for both the construction company and the installer. The background is based on the fact that installers do not calculate components and activities such as other building production, which makes it difficult to reconcile if an activity has been carried out in accordance with budget. Both parties agree that it is working hours that need to be checked, as this is where the difficulty of control lies. To be able to check real hours, knowledge of the planned number of hours is needed. The time schedule is an important tool in the project and should be included in reconciliation. Arcona and Nymans Elektriska are recommended to use existing control documents with certain appendixes for the measuring progress.

  • Sandberg, Marcus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Andersson Svorono, Gabriel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Undersökning av energideklarationer: Uppfyller de sitt syfte att bidra till en effektiv energianvändning i byggnader?2019Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    In 2002, a directive from EU stated that the countries should start keeping better track of how buildings consume energy. From this directive a law was introduced that implied that energy declarations now were to be established. The main purpose of energy declarations was for them to contribute to efficient energy use and a healthy indoor environment. This was to be achieved by giving a general view of the building’s energy status, as well as basis for investments in making the building more energy efficient. This master’s dissertation examines if energy declarations fulfill their purpose of contributing to an efficient energy use. After questioning of real estate company’s personnel and examining energy declarations, they proved to be considered adequate in showing a building’s general energy consumption. However, the action proposals are often considered too simplistic. Instead, many companies base their actions in order to make the building more efficient on their own personnel, their thorough investigation and detailed analysis of a building’s energy consumption. This detailed analysis gives a clearer picture of where energy can be saved and in what way actions should be made in order to be most efficient. The purpose of energy declarations is therefore only partially fulfilled.

  • Eriksson, Petter
    et al.
    KTH, School of Engineering Sciences (SCI).
    Dalbom, Daniel
    KTH, School of Engineering Sciences (SCI).
    Simulering av system med flera agenter genom användande av djup förstärkande inlärning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Reinforcement Learning has been getting a lot of attention in recent years, mostly through its use in teaching computers to play video and board games. In this report it is investigated how well algorithms from this area can be used to solve a multi-agent problem. The multi-agent problem to be solved is teaching robots how to transport items through a warehouse without colliding. A Q-learning based algorithm is proposed to solve the problem. Because of the scalability issues a DQN based algorithm is also proposed. The scalability issues arise in systems of higher complexity, in systems characterized by multiple agents or a large environment. It is shown that Qlearning fails to learn a good strategy in a reasonable time. Simulations are made to illustrate the behaviour of the proposed algorithms. The results of the simulations suggest that DQN performs considerably better compared to Q-learning when the dimensions of the problem are larger.

  • del Aguila Pla, Pol
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Inverse problems in signal processing: Functional optimization, parameter estimation and machine learning2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Inverse problems arise in any scientific endeavor. Indeed, it is seldom the case that our senses or basic instruments, i.e., the data, provide the answer we seek. It is only by using our understanding of how the world has generated the data, i.e., a model, that we can hope to infer what the data imply. Solving an inverse problem is, simply put, using a model to retrieve the information we seek from the data.

    In signal processing, systems are engineered to generate, process, or transmit signals, i.e., indexed data, in order to achieve some goal. The goal of a specific system could be to use an observed signal and its model to solve an inverse problem. However, the goal could also be to generate a signal so that it reveals a parameter to investigation by inverse problems. Inverse problems and signal processing overlap substantially, and rely on the same set of concepts and tools. This thesis lies at the intersection between them, and presents results in modeling, optimization, statistics, machine learning, biomedical imaging and automatic control.

    The novel scientific content of this thesis is contained in its seven composing publications, which are reproduced in Part II. In five of these, which are mostly motivated by a biomedical imaging application, a set of related optimization and machine learning approaches to source localization under diffusion and convolutional coding models are presented. These are included in Publications A, B, E, F and G, which also include contributions to the modeling and simulation of a specific family of image-based immunoassays. Publication C presents the analysis of a system for clock synchronization between two nodes connected by a channel, which is a problem of utmost relevance in automatic control. The system exploits a specific node design to generate a signal that enables the estimation of the synchronization parameters. In the analysis, substantial contributions to the identifiability of sawtooth signal models under different conditions are made. Finally, Publication D brings to light and proves results that have been largely overlooked by the signal processing community and characterize the information that quantized linear models contain about their location and scale parameters.

  • del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Inferences from quantized data - Likelihood logconcavityManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we present to the signal processing community the most general likelihood logconcavity statement for quantized data to date, together with its proof, which has never been published. In particular, we show how Prékopa’s theorem can be used to show that the likelihood for quantized linear models is jointly logconcave with respect to both its location and scale parameter in a broad range of cases. In order to show this result and explain the limitations of the proof technique, we study sets generated by combinations of points with positive semi-definite matrices whose sum is the identity.

  • Ruffa, Giorgio
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Towards unification of organ labeling in radiation therapy using a machine learning approach based on 3D geometries2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In radiation therapy, it is important to control the radiation dose absorbed by Organs at Risk (OARs). The OARs are represented as 3D volumes delineated by medical experts, typically using computed tomography images of the patient. The OARs are identified using user-provided text labels, which, due to a lack of enforcement of existing naming standards, are subject to a great level of heterogeneity. This condition negatively impacts the development of procedures that require vast amounts of standardized data, like organ segmentation algorithms and inter-institutional clinical studies. Previous work showed that supervised learning using deep-learning classifiers could be used to predict OARs labels. The input of this model was composed of 2D contours of the OARs, while the output was a standardized label. In this work, we expanded this approach by qualitatively comparing the performance of different machine learning algorithms trained on a clinical data set of anonymized prostate cancer patients from the Iridium Kankernetwerk clinic (Belgium). The data set was partitioned in a semi-automatic fashion using a divide-and-conquer-like approach and various 2D and 3D encodings of the OARs geometries were tested. Moreover, we implemented a reject class mechanism to assess if the inference probability yielded by the model could be used as a measure of confidence. The underlining goal was to restrict human intervention to rejected cases while allowing for a reliable and automatic standardization of the remaining ones. Our results show that a random forest model trained on simple 3D-based manually engineered features can achieve the twofold goal of high classification performance and reliable inferences. In contrast, 3D convolutional neural networks, while achieving similar classification results, produced wrong, but confident, predictions that could not be effectively rejected. We conclude that the random forest approach represents a promising solution for automatic OAR labels unification, and future works should investigate its applications on more diversified data sets.

  • Elers, Andreas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Continual imitation learning: Enhancing safe data set aggregation with elastic weight consolidation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The field of machine learning currently draws massive attention due to ad- vancements and successful applications announced in the last few years. One of these applications is self-driving vehicles. A machine learning model can learn to drive through behavior cloning. Behavior cloning uses an expert’s behavioral traces as training data. However, the model’s steering predictions influence the succeeding input to the model and thus the model’s input data will vary depending on earlier predictions. Eventually the vehicle may de- viate from the expert’s behavioral traces and fail due to encountering data it has not been trained on. This is the problem of sequential predictions. DAG- GER and its improvement SafeDAGGER are algorithms that enable training models in the sequential prediction domain. Both algorithms iteratively col- lect new data, aggregate new and old data and retrain models on all data to avoid catastrophically forgetting previous knowledge. The aggregation of data leads to problems with increasing model training times, memory requirements and requires that previous data is maintained forever. This thesis’s purpose is investigate whether or not SafeDAGGER can be improved with continual learning to create a more scalable and flexible algorithm. This thesis presents an improved algorithm called EWC-SD that uses the continual learning algo- rithm EWC to protect a model’s previous knowledge and thereby only train on new data. Training only on new data allows EWC-SD to have lower training times, memory requirements and avoid storing old data forever compared to the original SafeDAGGER. The different algorithms are evaluated in the con- text of self-driving vehicles on three tracks in the VBS3 simulator. The results show EWC-SD when trained on new data only does not reach the performance of SafeDAGGER. Adding a rehearsal buffer containing only 23 training exam- ples to EWC-SD allows it to outperform SafeDAGGER by reaching the same performance in half as many iterations. The conclusion is that EWC-SD with rehearsal solves the problems of increasing model training times, memory re- quirements and requiring access to all previous data imposed by data aggre- gation.

  • del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pellaco, Lissy
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Dwivedi, Satyam
    Ericsson Research.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Clock synchronization over networks - Identifiability of the sawtooth modelManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we analyze the two-node joint clocksynchronization and ranging problem. We focus on the case of nodes that employ time-to-digital converters to determine the range between them precisely. This specific design leads to a sawtooth model for the captured signal, which has not been studied in detail before from an estimation theory standpoint. In the study of this model, we recover the basic conclusion of a well-known article by Freris, Graham, and Kumar in clock synchronization. Additionally, we discover a surprising identifiability result on the sawtooth signal model: noise improves the theoretical condition of the estimation of the phase and offset parameters. To complete our study, we provide performance references for joint clock synchronization and ranging. In particular, we present the Cramér-Rao lower bounds that correspond to a linearization of our model, as well as a simulation study on the practical performance of basic estimation strategies under realistic parameters. With these performance references, we enable further research in estimation strategies using the sawtooth model and pave the path towards industrial use.

  • Satei, Mehdi
    KTH, School of Electrical Engineering and Computer Science (EECS).
    OTT Video-Oriented Mobile Applications Development Using Cross-Platform UI Frameworks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Google and Apple together are ruling the mobile phone industry with their operating systems, Android and iOS. Any mobile application willing to reach the vast majority of end-users, need to be run on both platforms. The issue, however, arises when considering that fact that developing an application for each platform requires different knowledge and code base. Cross-platform frameworks are emerged to overcome the mentioned issue by providing the possibility to develop a mobile application which works on multiple platforms with potentially a single code base.To investigate the capabilities of cross-platform frameworks, three frameworks were chosen to be compared; React Native backed by Facebook, Xamarin owned by Microsoft, and Flutter developed by Google. The chosen frameworks have been compared in the context of OTT Videooriented mobile applications. As a reference application OTT Flow, an OTT Video application developed by Accedo, has been used.The findings in this thesis shows that Xamarin is not a good choice for the purpose of this thesis since no advantages were witnessed in most of the criteria. React Native and Flutter, on the other hand, offer promising features which suit developing OTT applications. When considering the video-specific functionalities, however, React Native stood out slightly better. In fact, even though React Native is possibly the best choice among the mentioned frameworks for developing OTT Video-oriented mobile applications, the cross-platform frameworks are not mature enough in terms of video-specific functionalities support yet.

  • Landmark, David
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    The WELL Building StandardA Study of Bengt Dahlgren's office in Stockholm2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Throughout our lives, we spend approximately 80–90% of our time indoors, and the environment which wereside in is a key factor determining our comfort and well-being. A favorable indoor environment can enhance our quality of life whereas a less than favorable environment may have the opposite effect. A key ambition of several Green Building Certifications is the desire to reduce a building’s environmental impact and energy consumption, and, in addition, the ambition to provide a satisfying indoor environment.The WELL Building Standard (WELL) is an up and coming green building certification explicitly embracing comfort, health and well-being in the built environment. The standard covers seven over-arching topics forwhich the indoor environment is evaluated by; Air, Water, Nourishment, Light, Fitness, Comfort, andMind. Compared to well-established Green Building Certifications like LEED, BREEAM and Miljöbyggnad, the WELL standard is newly introduced on the Swedish market with few current applications.

    The purpose of this report is to apply WELL for Bengt Dahlgren’s office in Stockholm and provide resultsdemonstrating to what extent the office satisfies the certification. The report will also provide recommendedmeasures so as to reach a desired WELL certification grade. Furthermore, the compliance between WELL and the Swedish Green Building Certification Miljöbyggnad will be studied. The study has been carried out byreviewing the relevant policy, property and equipment documents; conducting technical measurements; andinspecting the conditions of the office area and its surroundings. Correspondence with stakeholders and actorsknowledgeable of the current state of the office have been a constant element throughout the project. 

    The results show that Bengt Dahlgren’s office currently do not fulfill the required preconditions to be eligiblefor a WELL certification. However, if those preconditions were to be addressed, a completed certificationwould result in a grade corresponding to Silver. By implementing the recommendations provided by the authorit should also be possible to reach the higher certification grade Gold. The study furthermore concludes that WELL and Miljöbyggnad only demonstrate limited overlap. By evaluating Bengt Dahlgren’s office in Stockholm, this report strives to give insight for how a Swedish office facility comply with the WELL certification. The work should also give light to new perspectives and applications regarding health, comfortand well-being which may not be included in traditional Green Building Certifications. The compliance for WELL with Swedish regulations, standards and norms have been treated in this report, however, the topic can be suggested as an area for future work, as there is room for an explicit study concerning this.

  • Das, Sandipan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Silicon photonics based MEMS tunable polarization rotator for optical communications2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There has been a huge surge in data traffic all over the world due to the rise of streamingmedia services and connected devices. The current demand in data traffic has alreadypushed the optical fiber in the internet architecture to the network edges and the trend isto push it as close as possible, to the CPU. Silicon photonics addresses this challenge byenabling miniaturized optical devices that use light to move huge amounts of data at veryhigh speeds with extremely low power. To further improve the data transmission capacity,one can make use of different polarizations of light. However, to take advantage ofdifferent polarizations, devices with on-chip polarization rotation capability are required.This is achieved by a tunable polarization rotator. Moreover, full control of polarizationrotation can also be utilized to realize a new class of components in integrated photonicsincluding polarization mode modulators, multiplexers, filters, as well as switches foradvanced optical signal processing, coherent communications, and sensing.This thesis introduces a novel tunable polarization rotator that uses microelectromechanicalsystems (MEMS) as its actuation principle. When voltage is applied to a MEMStunable silicon cantilever, a mechanical movement occurs, which in turn affects theoptical mode shape travelling through a waveguide, as a result of which the polarizationis rotated. In this work, a MEMS tunable polarization rotator is designed, fabricated,and characterized with a polarization extinction ratio of 10 dB, which works in 1530nm -1570nm wavelength spectrum. In addition to the MEMS tunable polarization rotator,in this thesis, a free standing polarization beam splitter of length 1.4 μm, the shortestreported to-date to our knowledge, was designed, fabricated, and characterized. Thetunable polarization rotator and beam splitter developed in this thesis have the potentialto increase the bandwidth and flexibility of current optical communication networks, andfind further applications in polarization diversity schemes for sensing.

  • Ahlin, Björn T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nitrogen Removal in a Vacuum Tank Degasser: An Investigation on the Nitrogen Removal Performance2019Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    The impending change of processes at SSAB Oxelösund due to the HYBRIT project, where the blast furnace and LD converter are to be replaced with an EAF will have a significant impact on the manufacturing of steel in Oxelösund. One issue that will arise is the nitrogen content in the steel. Sources claim that the nitrogen content in steel from an EAF route is substantially larger, 60-70 ppm, than in steel from a blast furnace and LD converter route, which have a nitrogen content of around 25 ppm. Therefore, the nitrogen removal capabilities of SSAB Oxelösund’s vacuum tank degasser were to be examined. Industrial trials were performed where the amount of slag during vacuum treatment was lowered. The intention was that half the amount of slag removed prior to vacuum treatment and later completely slag free. This was performed in an attempt to increase the effective reaction area, where nitrogen removal occurs. Due to some practical problems with the steel mill, the industrial trial were unfortunately cut short. Consequently, only trials with half the amount of slag were performed and compared to existing process data for standard praxis. Also, nitrogen removal calculations based on the industrial data were performed. A parameter representing the overall reaction rate, which is dependent on effective reaction area was obtained, validated and subsequently applied to a future case scenario. The results indicate that the reduction in slag amount does have the desired effect, increasing the said area and increasing the rate of nitrogen removal. However, the sample size is not nearly sufficient enough to determine this definitively. The conclusions reached were that the facility does have the possibility to decrease the increased nitrogen content down to reasonable levels, around 20-30 ppm. Albeit, an increase in vacuum treatment time is probably required. Another conclusion was that surface active elements, such as oxygen and sulphur greatly reduce the nitrogen removal. Therefore, efforts should be taken to remove these elements prior to vacuum treatment. In addition, it was established that the effective reaction area is of great importance for a successful nitrogen removal. Therefore, actions to maximise this area should be taken. Finally, it was stated that further research is necessary in order to fully understand nitrogen contamination prevention- and removal techniques

  • Henning, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Tollkuci, Endi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Energy simulation model for commercial buildings Beridarebanan 4, 11 and 77, with ice thermal storage2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    District cooling companies enforce a large penalty based on peak demands, which current cooling methods do not address properly. Building developers are exploring alternatives methods to reduce the said peak demands. The use of Ice Thermal Storage is an nontraditional method within the Scandinavian countries, but has shown to be a method to peak shave as well as load shifting in other regions of the worlds. The goal of the thesis was to "investigate the potential of ice thermal storage for cooling demand and peak shaving for Beridarebanan 4, 11, 77". The energy simulation was accomplished using the building performance simulator software IES VE. As inputs to the simulation, building data from the renovation project and corresponding weather data were used. The resulting simulation model was validated against renovated data with differences of 3,3% and 41,9% for the heating and cooling loads, respectively. The large discrepancy within cooling was determined to be weighted heavily by cooling strategy implemented within the building. When similar cooling strategies were implemented results were consistent with one another. This validation was investigated on a building, zone, and room level to look for consistency. The resulting simulated heating and cooling demands from IES VE were input into a then created ice thermal storage controller within MS Excel. In all, with the stable electrical and district cooling prices, a payback of 12 years was calculated for a 4,5 MWh, 6 hour storage ITS system. Results also show that for a 6 hour storage capacity,the controller exceeded the 1 000 kW price tier 4 hours out of the entire year, making it an ideal storage size. Current Swedish Electrical Market incentivize peak shaving rather than energy saving, accounting for nearly 80% of the yearly savings. The margin for earning more for the energy savings has negative consequences for potentially exceeding the 1 000 kW cooling threshold.

  • Perju, Dragos-Stefan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Applying Memoization as an Approximate Computing Method for Transiently Powered Systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Internet of Things (IoT) is becoming a more and more prevailing technology, as it not only makes the routine of our life easier, but it also helps industry and enteprise become more efficient. The high potential of IoT can also help support our own population on Earth, through precision agriculture, smart transportation, smart city and so on. It is therefore important that IoT is made scalable in a sustainable manner, in order to secure our own future as well.The current work is concerning transiently powered systems (TPS), which are embedded systems that use energy harvesting as their only power source. In their basic form, TPS suffer frequent reboots due to unreliable availability of energy from the environment. Initially, the throughput of such systems are therefore lower than their battery-enabled counterparts. To improve this, TPS involve checkpointing of RAM and processor state to non-volatile memory, as to keep computation progress saved throughout power loss intervals.The aim of this project is to lower the number of checkpoints necessary during an application run on a TPS in the generic case, by using approximate computing. The energy need of TPS is lowered using approximations, meaning more results are coming through when the system is working between power loss periods. For this study, the memoization technique is implemented in the form of a hash table. The Kalman filter is taken as the testing application of choice, to run on the Microchip SAM-L11 embedded platform.The memoization technique manages to yield an improvement for the Kalman application considered, versus the initial baseline version of the program. A user is allowed to ”balance” between more energy savings but more inaccurate results or the opposite, by adjusting a ”quality knob” variable epsilon ϵ.For example, for an epsilon ϵ = 0.7, the improvement is of 32% fewer checkpoints needed than for the baseline version, with the output deviating by 42% on average and 71% at its maximum point.The proof of concept has been made, being that approximate computing can indeed improve the throughput of TPS and make them more feasiable. It is pointed out however that only one single application type was tested, with a certain input trace. The hash table method implemented can behave differently depending on what application and/or data it is working with. It is therefore suggested that a pre-analysis of the specific dataset and application can be done at design time, in order to check feasiability of applying approximations for the certain case considered.

  • Zhao, Yu
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Channel Reconstruction for High-Rank User Equipment2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a 5 Generation massive Multiple Input Multiple Output radio network, the Channel State Information is playing a central role in the algorithm design and system evaluation. However, Acquisition of Channel State Information consumes system resources (e.g. time, frequency) which in turn decrease the link utilization, i.e. fewer resources left for actual data transmission. This problem is more apparent in a scenario when User Equipment terminals have multi-antennas and it would be beneficial to obtain Channel State Information between Base Station and different User Equipment antennas e.g. for purpose of high rank (number of streams) transmission towards this User Equipment. Typically, in current industrial implementations, in order to not waste system resources, Channel State Information is obtained for only one of the User Equipment antennas which then limits the downlink transmission rank to 1. Hence, we purpose a method based on Deep learning technique. In this paper, multi-layer perception and convolutional neural network are implemented. Data are generated by MATLAB simulator using the parameters provided by Huawei Technologies Co., Ltd. Finally, the model proposed by this project provides the best performance compared to the baseline algorithms.

  • Brus, Alexander
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Validation of energy efficiency requirements for machine tools and industrial washing machines2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Production equipment accounts for a large portion of the energy use from industry. But so far there has been no standardized way of requiring energy efficiency when purchasing a new machine. Scania is therefore implementing energy efficiency requirements in their purchasing process for production equipment. As a part of this, there needs to be a way of validating that the requirements have been fulfilled. This study aims to find how requirements on energy efficiency in production equipment can be validated in a user friendly and time efficient way. Firstly, the energy efficiency requirements set by Scania and by regulations are mapped. Then these requirements are clearly defined to enable a validation. Two component-level measurements of one machine tool and one industrial washing machine are analyzed. And then a cost analysis is conducted to determine the timespan that can be said to be time efficient for a validation procedure. The results from this are used to develop a validation method and an interactive protocol to make the validation more user friendly. This method is then tested through a simulated validation.

    The method proposed consists of two parts, an inspection and a measurement. The inspection is purely visual and validates the requirements on efficiency class for electrical motors and pumps, as well as requirements of specific equipment. The measurement is performed by running the machine through four different machine states in eight steps and validates requirements on when energy is used, and how much is used. The proposed method validates all energy efficiency requirements set by Scania for machine tools and industrial washing machines. It can be performed in a timespan that is far shorter than what is cost efficient. The proposed method can validate requirements on the energy use from any electrical components, compressed air use, and visually confirm that required equipment is present and some of its properties based on labelling. It will also be able to validate any new requirements on the energy use of electrical components, meaning it can easily be applied to other types of production equipment.

  • Bila, Kristi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Fatigue Analysis of a Lively Footbridge2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The commitment of building aesthetic bridges made of stiff materials results in theconstruction of slender structures highly susceptible to dynamic loading. In the caseof footbridges located over a highly trafficked highway, such dynamic loads maybe the aerodynamic pressure induced by the heavy trucks passing underneath thestructure and the pedestrian loading involving a pedestrian running and jumping.There have been reported cases in the literature that these types of dynamic eventscan cause discomfort to the users of the bridge, and thus, footbridges are usuallychecked in the serviceability limit state. However, footbridges are not checked forfatigue damage since the design codes do not demand fatigue analysis.In the present master thesis, a hypothesis is made: the dynamic loading actingon footbridges can cause fatigue damage. To test this hypothesis, a case study wasconsidered. The Smista bridge was chosen, which is a footbridge with noticeablevibrations even with the single action of a pedestrian running on the bridge oreven when a single truck passes underneath the bridge. The bridge was simulatednumerically using a 3D shell finite element model. Four load cases were studied:the aerodynamic pressure induced by the heavy trucks passing below the bridge,the pedestrian jumping in the middle of the bridge, the pedestrian running in thecenterline of the bridge and the pedestrian running near the edge of the bridge.The results showed that the dynamic events applied on the bridge did not producehigh enough response and stresses to account for fatigue damage accumulation.Therefore, it is concluded that fatigue design of such bridges, although very livelyand which can cause high discomfort to people, should not be added as a designcriteria in the design codes.

  • Rylander, Katarina
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Municipalities' ability to adapt the existing built environment to the changing climate: A case study of Täby, Vellinge, and Gothenburg2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the most challenging issues within the planning and development process of our cities and societies is the changing climate that already can be seen in several parts of the world. To be able to decrease the cities’ and societies’ vulnerability towards these projections it is important to actively work with climate adaptation. Today, the majority of the climate adaptation measures are implemented in new developments, and not in the same extent in the existing built environment. Because the projected climate changes will affect all parts of the cities and societies it is important to work with an overarching climate adaptation. Within the Swedish context, the municipality has an important role in the work with climate adaptation. The aim of this master thesis is to generate an understanding of how Swedish municipalities work with climate adaptation within the existing built environment, and what challenges they face within their work. Additionally, the study will look at how the current legislation affects the municipal climate adaptation work, and how the new amendments in PBL, will affect the municipalities’ work. Three municipalities (Täby, Vellinge, and Gothenburg) have been studied to be able to conduct this master thesis, where sixteen interviewees from the municipalities, as well as from the Stockholm County Administrative Board and from Sweco, a Swedish consulting company, have been interviewed. The results from the study show that several challenges that the municipalities, in the current situation, are facing and are affecting their climate adaptation work. The main challenges that was identifies were the uncertain forecasts, the political will and priorities, the division of responsibility, the financial responsibility, and conflicting legislations. These challenges are creating limitations and difficulties for the municipalities to act in the issue of adapting to the changing climate, especially within the existing built environment. In the current situation, the three studies municipalities have started their climate adaptation work but are facing difficulties with going forward in the process.

  • Johansson, Jonas
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Jonsson Ewerbring, Marcus
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Användning av sensordata för att detektera smartphoneanvändares transportmedel2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A way to inform smartphone users about their climate impact is by automatically identifying their means of transport and use the information to estimate the user's emissions of greenhouse gases. The aim of this project was to create an overview of existing solutions and methods for detecting smartphone users' means of transport and evaluating how a system performs when test data is collected in a different geographical area than the data used to train the system. Evaluation of the system was done via quantitative methods where sensor data was collected and used to test the system. Sensor data was collected by walking, still, train, bus and car. The result is a system that, with varying probability, can determine the means of transport in Sweden. The system's total accuracy was 29 percentage points lower when data collected in Sweden was used in the tests compared to data collected in the same geographical area as the training data. The conclusion is that it can be problematic to apply a solution in a different geographical area than where the solution was developed for. The tests showed that vehicle detection seems particularly sensitive to changing geographical context.

  • Sonono, Tofik
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Interoperable Retransmission Protocols with Low Latency and Constrained Delay: A Performance Evaluation of RIST and SRT2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The media industry has during the last decade migrated services from dedicated medianetworks to more shared resources and lately also the public internet and public data centers. Inorder to cater for such transition, several protocols have been designed to meet the demand forhigh-quality media transport over lossy infrastructure, protocols such as SRT and RIST. Thepurpose of Reliable Internet Stream Transport (RIST) and Secure Reliable Transport (SRT) is tohave all vendors of broadcasting equipment support an interoperable way of communication. Thelack of interoperability locks consumers into one particular vendor’s family of products - most oftenthis equipment only supports a proprietary technology. Interoperability creates a more competitivemarket space which benefits consumers and gives vendors an incentive to be more innovative intheir solutions.

    The purpose of this thesis is to assess the performance of these protocols by comparing theirperformance to a proprietary solution (named ÖÖÖ in this thesis and seen as an establishedsolution in the industry). The challenge is to test these protocols in a lab environment, but have theresults represent real-world use. For this, a large subset of samples is needed along with samplesmeasured over a long period. This sampling was made possible by writing a script which automatesthe sampling process.

    The results indicate that the versions of RIST and SRT tested in this thesis to some extentcompare well to the selected established protocol (ÖÖÖ). In many scenarios, SRT even did muchbetter, mainly when a line with a single feed was tested. For instance, when the network suffered a2% drop rate and utilized retransmission SRT performed the best and was the only protocol whichhad some samples where no packets were dropped during one hour of measurements. Whenrunning all three protocols at the same time, SRT also did the best in a network with up to 12% droprate. The results in this thesis should give a broadcaster an idea of which of these protocols willfulfill their requirements in a broadcast application.