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  • 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.

  • Kouach, Mona
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Methods for modelling lattice structures2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The application of lattice structures have become increasingly popular as additive manufacturing (AM) opens up the possibility to manufacture complex configurations. However, modelling such structures can be computationally expensive. The following thesis has been conducted in order for the department of Structural Analysis, at SAAB in Järfälla, to converge with the future use of AM and lattice structures. An approach to model lattice structures using homogenization is presented where three similar methods involving representative volume element (RVE) have been developed and evaluated. The stiffness matrices, of the RVEs, for different sizes of lattice structures, comprising of BCC strut-based units, have been obtained. The stiffness matrices were compared and analysed on a larger solid structure in order to see the deformational predictability of a lattice-based structure of the same size. The results showed that all methods were good approximations with slight differences in terms of boundary conditions (BCs) at the outer edge. The comparative analyses showed that two of the three methods matches the deformational predictability. The BCs in all methods have different influences which makes it pivotal to establish the BCs of the structure before using the approach presented in this thesis.

  • Rudd, Clive
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Energialstring för drivande av smart enhet utan batterier: Design av ett energialstrande system för smart sko genom piezoelektronik och solceller2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The past couple of decades gave rise to smartphones, smart watches, and smart homes. Now researchers are looking for ways to make smart clothing. One use case of smart clothing is smart shoes which can give some very useful sensed information especially in the sports industry and healthcare. Such sensed data include temperature, distance and calories, fall detection and many more. This application scenario can be designed to be battery free if we make use of the human motion and solar power. Many research papers exist which present how to exploit swing and shock excitations from the shoes to harvest energy. In this project this energy combined with solar energy will be used to power a low driven MCU. I design a pcb which include solar panels and piezoelectric modules to store the energy in supercapacitors. The goal is to integrate this pcb in a shoe, meaning that it has to have a small size and low power. The results of the project showed that a constant voltage at 1.8 volt could be achieved however recharge time is a factor to take into consideration. The system showed positive results for activities including movements and sun such as hiking.

  • Thölberg, Anton
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Grönblått Stockholm: Förutsättningar för klimatsmarta snötippningsplatser2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Climate scientists around the world generally agree that human activities affect the ongoing climate change. From a global perspective, many countries continue to emit large quantities of greenhouse gases and, according to several studies, the consequences of these are expected to continue well into the future, even if the global temperature rise is kept below two degrees. For the Stockholm region, analyzes of weather data have been able to observe that the summers have become warmer and the winters less snowy, with more precipitation falling in the form of rain. In the future, more cases of heat waves and intense rainfall are also expected to occur, which will result in new sustainability challenges. A strategy that has proven to be effective in mitigating the effects of climate change is the promotion of green and blue structure, such as urban trees and sustainable stormwater systems.

    The purpose of this study has been to develop a knowledge base for how green-blue infrastructure can be integrated into the built environment in order to support the City of Stockholm in the ongoing climate adaptation work. The work is based on a pilot project developed by the Traffic Administration Office in Stockholm, within which surfaces have been identified for snow disposal in the district areas of Bromma and Spånga-Tensta. Based on the results of this project, a qualitative evaluation has then been made regarding the potential of two designated sites to be able to handle current and future temperature and precipitation patterns. The methods used in this work are a literature study and a case study.

    The findings of the study showed that in the work of promoting green and blue infrastructures it is possible to generate multifunctional land use that can contribute to both temperature regulation and flood management. Furthermore, the results additionally showed that the selected locations had different prerequisites for being able to function as snow landfills and to promote temperature control and flood management. Radiation temperature and rainfall data also indicated that the sites are at risk of severe heat and additional flooding in the future, which is to some extent assumed to be due to a limited amount of vegetation. The consequences of the results also indicated that for urban planning and climate adaptation in general, there is a need to plan for multifunctional solutions as the city grows and densifies. A starting point for this is to better utilize nature and its services in order to be able to provide a local climate in which man and other life can live and thrive, even in times of change.

  • Vlassopoulou, Efstathia
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Urban form and sustainability: Comparison between low-rise “garden cities” and  high-rise “compact cities” of suburban areas2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Urbanization and climate change are two of the most important issues of our days. Many attempts have been made to define the most sustainable way to organise cities in order to cope with the increased population, while simultaneously being climate friendly, socially acceptable and economically viable. This master thesis focuses on the comparison of the sustainability performance of two particular theoretically planned urban forms, located in the suburban area of Stockholm – a “compact city”-like neighborhood and a “garden-city”-like neighbourhood. It was decided that the focus would be on the carbon footprint of the representative residences of each urban form, with the help of Life Cycle Assessment (LCA); and that overall sustainability criteria for neighbourhoods would after wards be assessed, having a certification system forsustainable neighbourhoods (CityLab for districts, in particular) as a framework for a – mostly theoreticalassessment. After the exploring of the differences in the sustainability performance(environmental and social) of the two assessed urban forms, a discussion is made concerning the relationship between urban form and sustainability and conditions under which the most sustainable urban form could be achieved. The results of the analysis highlight that the concept “one size fits all” cannot conform to urban planning decisions, since cities should be able to adjust to the needs of each generation.

  • Salazar Ruiz Velasco, Maria Fernanda
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Food Waste Management in a Circular Economy Perspective: A case study of Swedish juice plant Loviseberg presseri AB2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One third of all the food produced for human consumption is being wasted all around the world. The recovery and optimum use of this food waste is vital to support the growing population and food demand. The main objective of this research is to identify the optimum use of organic waste, using a circular economy approach, to generate recommendations that help industries in the food sector to reduce and valorize waste.

    A case study for food waste management alternative selection with the Swedish juice plant Loviseberg presseri AB is presented. This study furthermore proposes a detailed operation procedure of the selected options according to the results exploring the potential add value to the residue remaining from cold-pressed juice process. It was found that 49% of the total weight from raw material is wasted after the extraction process, being apple and orange the larger contributors.

    The research identified and recommended, for the specific case study, that the optimum use of apple pomace is used for ingredient for human consumption products, followed by animal feed and pectin production. As for the orange waste, it was identified to be used for essential oil extraction, followed by animal feed and anaerobic digestion. Furthermore, the results of the research shows, that a combination of the different waste management alternatives would also benefit the company. The research also identified potential challenges as well as benefits, which depend in the specific waste analyzed.

  • Jazzar, Jacques
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Methods of post-treatment of aerodynamic tests of engine boosters2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aerodynamics studies in a booster such as analysis of the flow through the whole component or study of local turbulent phenomenon constitute a crucial part of its development in order to get better overall performances, like efficiency of the compressor and compression ratio. In order to put in perspective the computational predictions, it is critical to obtain sets of data from tests to caliber numerical analyses and to assure the booster respects design specifications. Aerodynamics testing is then an important part of the development of a compressor. However, it is complicated to obtain such values for many reasons: time constraints, problems regarding support, important costs etc. Thus, it is important to get as much information as possible from these tests data in a limited period in order to spend more time in results interpretation and less in treating raw data. Thus, an optimized tool of treatment to first deduce results from test data; and then to compare different engines or different sets of tests data, to get a wider state of the art and to avoid time-consuming analyses was needed. In order to do so, the first part of the development consists in investigating the existing methods to extract and analyze data from tests already used, and then deducing a general methodology to obtain from raw measures the performances of the studied booster compared to other available data. Once the methods have been set up and validated, the tool in itself was implemented in a practical way. Then, it was important to validate it on real tests values and to observe if it was adjustable for all kind of aerodynamics tests.

  • Johnson, Emelie
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Per- and Polyfluoroalkyl Substances (PFASs) Removal from Landfill Leachate: Efficiency Evaluation in Column Experiments2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are known for their wide spread in the environment, their persistent properties and their ability of biomagnification through the food chain. With properties such as oil and water repellence, temperature resistance and a long lifespan they have been frequently used in various areas, e.g. hygiene products such as shampoo and tooth paste as well as in the firefighting industry as firefighting foam. They are therefore commonly found in leachate from landfills. Up to now, there is a lack of studies investigating methods of how to treat PFAS-contaminated leachate and hence more research in this area and development of suitable treatment technologies is needed.

    In this study, column experiments with granulated activated carbon (GAC), anion exchanger (AE) resin and peat mixed with ash were performed. The results showed that AE removed PFAS more efficiently than GAC, that longer chains had a higher sorption ability than shorter chains and that perfluorinated sulfonic acids (PFSAs) a higher sorption ability than perfluorinated carboxylic acids (PFCAs). The peat-ash columns had a slower flow and only 5bed volumes (BVs) of leachate were treated. Hence, these results could not be compared with GAC and AE. For GAC and AE 1920 BVs and 1840 BVs, respectively, were treated and none of the filters got fully saturated. The conclusion of the study is that AE is likely a more suitable treatment technology for this purpose than GAC but more research is needed to determine the breakthrough and design PFAS treatment for leachate.

  • Janoco, Martin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Evaluating the sustainability of vegetarian, vegan, and New Nordic diets in Sweden: Combining environmental and nutritional aspects2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Changing the western dietary pattern toward a healthier diet with reduced intake of animal foods is a commonly recognized strategy in the ongoing effort for global sustainability. Since animal foods tend to have a high environmental impact, vegetarian diets are often suggested as an ecological alternative to the typical Western diet. The low sum of environmental impacts, however, does not on its own necessarily translate to a sustainable diet. Sustainability encompasses many other aspects, such as nutritional adequacy, affordability, and cultural acceptability. As regards the elimination of animal foods in particular, health-related aspects ought to be considered since some nutrients are supplied primarily via animal products which may lead to nutritional deficiencies and potential negative health effects in the long term. Furthermore, since the main function of diets is the supply of (adequate) nutrition, the environmental impacts of diets ought to be compared in light of their nutritional quality. In this project the environmental impact on climate change, land use, blue water footprint, and biodiversity damage potential of four diets is assessed, along with their nutritional adequacy and financial cost. The four assessed diets are: an average Swedish diet, New Nordic diet, vegetarian diet, and vegan diet. The environmental impacts are normalized with a nutritient-rich diet score (NRD) to compare the impacts of diets in relation to their nutritional quality. The vegan diet, followed by the vegetarian diet, resulted in the lowest overall impact with the exception of blue water footprint, however, the normalization with NRD score lessened the relative differences between the New Nordic, vegetarian, and vegan diet. Furthermore, the nutritional assessment showed a potentially unsustainable intake of vitamin D in vegetarians and vit. D and B12 in vegans, which is not properly reflected in the nutritional quality score. Nevertheless, the use of the nutritional score is fairly simple and provides opportunity for linking the health-related aspect of diets to their environmental impact. Joined with indicators on other sustainability aspects, such as the economic, this method can offer a more holistic picture of the sustainability of diets.

  • Dubrova, Elena
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Näslund, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Degen, Bernhard
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Gawell, Anders
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Yu, Yang
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    CRC-PUF: A Machine Learning Attack Resistant Lightweight PUF Construction2019In: 2019 IEEE European Symposium on Security and Privacy Workshops (EuroS&PW), IEEE conference proceedings, 2019, p. 264-271-Conference paper (Refereed)
    Abstract [en]

    Adversarial machine learning is an emerging threat to security of Machine Learning (ML)-based systems. However, we can potentially use it as a weapon against ML-based attacks. In this paper, we focus on protecting Physical Unclonable Functions (PUFs) against ML-based modeling attacks. PUFs are an important cryptographic primitive for secret key generation and challenge-response authentication. However, none of the existing PUF constructions are both ML attack resistant and sufficiently lightweight to fit low-end embedded devices. We present a lightweight PUF construction, CRC-PUF, in which input challenges are de-synchronized from output responses to make a PUF model difficult to learn. The de-synchronization is done by an input transformation based on a Cyclic Redundancy Check (CRC). By changing the CRC generator polynomial for each new response, we assure that success probability of recovering the transformed

  • Kajita, Heidi Svenningsen
    et al.
    kajita, masashi
    Material Includes2017Book (Other academic)
  • Chyad, Yousif
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Ali, Khadija
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Logistik vid begränsat utrymme: Jämförelsestudie mellan fyra byggarbetsplatser2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Planning of material handling in limited spaces has become more relevant in the construction industry and since material cannot always be delivered at the right time in the right place, a delay in the flow chain is created. Each construction site has unique conditions and thus different solutions.In this thesis, four workplaces at Peab have been visited and inspected. The purpose of the thesis was to explore the problems that arise with the logistics in a limited space and find solutions that can be implemented on future construction projects.The aim of the study was to find the common factors that exist for the workplaces within a small area and find ways of working that can change the planning and execution of logistics.Surveys to professional workers and interviews with site managers and supervisors contributed with information to the report.After compiling the thesis work, the result shows that there are opportunities to change the working method of the work management to increase efficiency and productivity.In the study, it appears that there is a lack of communication in the workplaces as a large number of workers do not know when the next delivery of material takes place. In addition, the professional workers admit that they did not have a great influence over the business. Recommended solutions that were developed in the study were experience feedback and further development of the APD plan.

  • Public defence: 2019-10-22 13:15 Seminar room, Dept. of Solid Mechanics, Stockholm
    Brandberg, August
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Insights in paper and paperboard performance by fiber network micromechanics2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fiber networks are ubiquitous due to their low cost and high ratio of mechanical performance to weight. Fiber networks made of cellulose fibers from trees are used as information carriers (paper) and as packaging (board). Often the ideal product is both mechanically sturdy and possible to print on. This thesis investigates the underlying reasons for the mechanical performance of paper and board through the discretization and direct simulation of every fiber in the network.

    In Paper A the effect of fiber-fiber bond geometry on sheet stiffness is investigated. Many packaging products seek to maximize the bending stiffness by employing stiff outer layers and a bulkier layer in the middle. In bulky sheets, the fibers are frequently uncollapsed resulting in a more compliant bonded segment. Because all the loads in the network are transferred via the bonds, such compliance can cause unexpectedly large decreases in mechanical performance. Although many models have been presented which aim to predict the tensile stiffness of a sheet, these predictions tend to overestimate the resulting stiffness. One reason is that the bonds are generally considered rigid. By finite element simulations, we demonstrated the effect of the lumina configuration on the stiffness of the bonded segment on the scale of single fiber-to-fiber bonds, and that the average state of the fiber lumen has a marked effect on the macroscopic response of fiber networks when the network is bulky, has few bonds, or has a low grammage.

    Compression strength is central in many industrial applications. In paper B we recreated the short span compression test in a simulation setting. The networks considered are fully three-dimensional and have a grammage of 80 to 400 gsm, which is the industrially relevant range. By modeling compression strength at the level of individual fibers and bonds, we showed that fiber level buckling or bifurcation phenomena are unlikely to appear at the loads at which the macroscopic sheet fails.

    In paper C, we developed a micromechanical model to study the creation of curl in paper sheets subjected to a moisture gradient through the sheet. A moisture gradient is always created during the printing process, which may lead to out-of-plane dimensional instability. We showed that the swelling anisotropy of individual fibers bonded at non-parallel angles causes an additional contribution to the curl observed on the sheet level.

  • Möller, Anton
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Piezoelectric tuning of integrated photonic delay circuits2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Shokri-Ghadikolaei, Hossein
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering. COMELEC Department, Telecom ParisTech, Paris, France.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Learning and Data Selection in Big Datasets2019In: Proceedings of the 36th International Conference on MachineLearning, Long Beach, California, PMLR 97, 2019., 2019Conference paper (Refereed)
    Abstract [en]

    Finding a dataset of minimal cardinality to characterize the optimal parameters of a model is of paramount importance in machine learning and distributed optimization over a network. This paper investigates the compressibility of large datasets. More specifically, we propose a framework that jointly learns the input-output mapping as well as the most representative samples of the dataset (sufficient dataset). Our analytical results show that the cardinality of the sufficient dataset increases sub-linearly with respect to the original dataset size. Numerical evaluations of real datasets reveal a large compressibility, up to 95%, without a noticeable drop in the learnability performance, measured by the generalization error.

  • Stigsson, Martin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Selroos, Jan-Olof
    SKB, Swedish Nuclear Fuel and Waste Management Co.
    A method to estimate flow and transport properties of sheared synthetic fractures in crystalline rock with different roughness under varying normal stressManuscript (preprint) (Other academic)
  • Stigsson, Martin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Some aspects on the applicability of peak shear strength criteriaManuscript (preprint) (Other academic)
  • Grinbergs, Lauris
    et al.
    Höglund, Ingemar
    Ottoson, Göran
    Åtgärder för förbättrad mögelresistens hos beklädnader i våtrum1995Report (Other academic)
    Abstract [sv]

    Val av beklädnader i våtrum är viktigt, då hårda krav ställs på dem:

    hög luftfuktighet, vattenspolning och mekanisk nötning (skrapning). De måste vara lätta att rengöra och får inte medverka till mögelbildning. Laboratorieförsök utfördes i speciellt uppbyggda duschkabiner i full skala och under verklighetstrogna förutsättningar. Under två faser, I och Il, studerades hur åtta genuina våtrumssvampar utvecklats och angripit ytskikt vid varierande villkor avseende luftfuktighet, fritt vatten, näringstillgång och mögelsporbildning. Parallellt med kabinförsöken i fas I bestämdes också mögelresistensen i en serie med mindre provplattor, s k "panel-tests".

    Även "case-studies" av mögelpåväxt i våtrum i praktiken ingick. Rapporten redogör detaljerat för objekt, näringssubstrat, våtrumssvampar, antal kolonier, påväxtgrad, pH-värden etc samt praktiska konsekvenser.

  • Grinbergs, Lauris
    KTH, School of Architecture and the Built Environment (ABE).
    Mögelresistens hos beklädnader i våtrum1992Report (Other academic)
    Abstract [en]

    Mycological tests have been carried out both in full scale testing chambers and on a large number of control -plates of various types of wall wet room-systems using species of genuine wet-room mould. The investigation comprised determination of the mould resistance as well as the effectiveness of sanitary measures . In order to quantify the mould growth on the wall systems two new quantities were invented.

    The degree of mould growth (påväxtgrad) is the amount of mould (part of the area} that affects a wall system, in a scale from O to 5 (0 stands for none and 5 stands for very severe mould growth).

    The degree of damage (skadegrad) is the amount of mould, discoloration etc. that is present on the wall system after cleaning up measures have been taken. I consists of a scale from· 0 to 5 (0 stands for none and 5 stands for very severe presence of mould and discoloration).

    According to the degree of damage, the four main groups of tested wet room wall systems obtained the results as follows

    * Plastic laminate    0

    * Cheramic tiles     0-1

    * Plastic mats      0.5-3.5

    * Wowen glassfibre + paint       0.5-4.5

    The best results were achieved by the plastic laminate system that was practically free from mould growth and discoloration . Regarding to cheramic tiles the test results show that the joints between the tiles were attacked by mould. The sanitation test with four different fungicides showed that the fungicides were practically equal in terms of inhibiting fungal growth and that the durability was limited (3 months).

  • Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Impact of Normal Stress Caused Closure on Fluid Flow and Solute Retention in Rock Fractures2018Conference paper (Refereed)
    Abstract [en]

    Modeling of coupled hydro-mechanical and chemical (HMC) processes in fractured rocks is an important topic for many geoengineering projects.  Over the past decades, many efforts have been devoted to study the flow and transport in single fractures with consideration of mechanical effects. It is generally known that the mechanical effects, i.e. normal and shear deformation, significantly affect fluid flow and solute transport processes in rough-walled rock fractures since the deformation may largely alter the structure of fracture apertures that directly controls transmissivity. Due to complicated physical processes combined with complexity of geometry structures, many issues remain open questions, such as fracture surface roughness characterization, deformation dependence of transmissivity and advective transport in natural rock fractures. In this work, we attempt to investigate the impact of stress caused closure on fluid flow and solute advective transport in a rough-walled fracture through numerical modeling.  A rough-walled fracture model is created based on a laser-scanned rock surface. The Bandis’s model is used to describe the fracture closure subject to normal stress. The flow is modeled by solving Reynolds equation and the advective transport is simulated through Lagrangian particle tracking. The results show that the normal stress caused fracture closure creates asperity contacts and reduces the mean aperture, which significantly reduces transmissivity, and affects the travel time and transport resistance. With increases of normal stress, the specific surface area reduces nonlinearly due to the nonlinear closure. In practice, especially for important hydrogeological projects, e.g. nuclear waste disposal, it is important to consider the coupled HMC processes in design and risk assessment.

  • de Alwis, Pahansen
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Garme, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Monitoring and characterization of vibration and shock conditions aboard high-performance marine craft2018In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 233, no 4, p. 1068-1081Article in journal (Refereed)
    Abstract [en]

    The stochastic environmental conditions together with craft design and operational characteristics make it difficult to predict the vibration environments aboard high-performance marine craft, particularly the risk of impact acceleration events and the shock component of the exposure often being associated with structural failure and human injuries. The different timescales and the magnitudes involved complicate the real-time analysis of vibration and shock conditions aboard these craft. The article introduces a new measure, severity index, indicating the risk of severe impact acceleration, and proposes a method for real-time feedback on the severity of impact exposure together with accumulated vibration exposure. The method analyzes the immediate 60s of vibration exposure history and computes the severity of impact exposure as for the present state based on severity index. The severity index probes the characteristic of the present acceleration stochastic process, that is, the risk of an upcoming heavy impact, and serves as an alert to the crew. The accumulated vibration exposure, important for mapping and logging the crew exposure, is determined by the ISO 2631:1997 vibration dose value. The severity due to the impact and accumulated vibration exposure is communicated to the crew every second as a color-coded indicator: green, yellow and red, representing low, medium and high, based on defined impact and dose limits. The severity index and feedback method are developed and validated by a data set of 27 three-hour simulations of a planning craft in irregular waves and verified for its feasibility in real-world applications by full-scale acceleration data recorded aboard high-speed planing craft in operation.

  • Brandberg, August
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Kulachenko, Artem
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    The effect of geometry changes on the mechanical stiffness of fibre-fibre bonds2017In: Advances in Pulp and Paper Research, Manchester, 2017, p. 683-719Conference paper (Refereed)
  • Dewulf, Art
    et al.
    Karpouzoglou, Timos
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Warner, Jeroen
    Wesselink, Anna
    Mao, Feng
    Vos, Jeroen
    Tamas, Peter
    Groot, Annemarie E.
    Heijmans, Annelies
    Ahmed, Farhana
    Hoang, Long
    Vij, Sumit
    Buytaert, Wouter
    The power to define resilience in social–hydrological systems: Toward a power-sensitive resilience framework2019In: WIREs Water, ISSN 0935-879X, E-ISSN 2049-1948, article id e1377Article in journal (Refereed)
    Abstract [en]

    Abstract Since the early work on defining and analyzing resilience in domains such as engineering, ecology and psychology, the concept has gained significant traction in many fields of research and practice. It has also become a very powerful justification for various policy goals in the water sector, evident in terms like flood resilience, river resilience, and water resilience. At the same time, a substantial body of literature has developed that questions the resilience concept's systems ontology, natural science roots and alleged conservatism, and criticizes resilience thinking for not addressing power issues. In this study, we review these critiques with the aim to develop a framework for power-sensitive resilience analysis. We build on the three faces of power to conceptualize the power to define resilience. We structure our discussion of the relevant literature into five questions that need to be reflected upon when applying the resilience concept to social?hydrological systems. These questions address: (a) resilience of what, (b) resilience at what scale, (c) resilience to what, (d) resilience for what purpose, and (e) resilience for whom; and the implications of the political choices involved in defining these parameters for resilience building or analysis. Explicitly considering these questions enables making political choices explicit in order to support negotiation or contestation on how resilience is defined and used. This article is categorized under: Human Water > Water Governance. Engineering Water > Planning Water.

  • Ghafoory, Jones
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Numerical Analysis, NA.
    p-Laplacian Spectral Clustering Applied in Software Testing2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Software testing plays a vital role in the software development life cycle. Having a more accurate and cost-efficient testing process is still demanded in the industry. Thus, test optimization becomes an important topic in both state of the art and state of the practice. Software testing today can be performed manually, automatically or semi-automatically. A manual test procedure is still popular for testing for instance in safety critical systems. For testing a software product manually, we need to create a set of manual test case specifications. The number of required test cases for testing a product is dependent on the product size, complexity, the company policies, etc. Moreover, generating and executing test cases manually is a time and resource consuming process. Therefore, ranking the test cases for execution can help us reduce the testing cost and also release the product faster to the market. In order to rank test cases for execution, we need to distinguish test cases from each other. In other words, the properties of each test case should be detected in advance. Requirement coverage is detected as a critical criterion for test cases optimization. In this thesis we propose an approach based on a $p$-Laplacian Spectral Clustering for detecting the traceability matrix between manual test cases and the requirements, in order to find the requirement coverage for the test cases. However, the feasibility of the proposed approach is studied by an empirical evaluation which has been performed on a railway use-case at Bombardier Transportation in Sweden. Through the experiments performed using our proposed method it was able to achieve an $F_1$-score up to $4.4\%$. Although the proposed approach under-performed for this specific problem compared to previous studies, it was possible to get some insights on what limitations $p$-Laplacian Spectral Clustering have and how it could potentially be modified for similar kind of problems.

  • Mätzke, Margitta
    et al.
    Johannes Kepler University, Inst of Politics and Social Policy.
    Anttonen, Anneli
    University of Tampere, Faculty of Social Sciences.
    Brokking, Peter
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Javornik, Jana
    University of East London, Sociology and Social Policy.
    Public Policy Conceptions: Priorities of Social Service Provision in Europe2017In: Social Services Disrupted: Changes, Challenges and Policy Implications for Europe in Times of Austerity / [ed] Flavia Martinelli, Anneli Anttonen and Margitta Mätzke, Cheltenham: Edward Elgar Publishing, 2017, p. 71-91Chapter in book (Refereed)
  • Carrion Domenech, Luis Enrique
    KTH, School of Industrial Engineering and Management (ITM).
    Study of high flash point ethyl alcohol-based secondary fluids applied in Ground Source Heat Pumps systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ethyl alcohol (ethanol) as secondary fluids is very popular as heat transfer fluid for indirect refrigeration system with ground source heat pump systems (GSHP) in several countries such as Sweden, Norway, Switzerland, Finland and other European countries. There have been several researches about the future ofthe refrigeration sector, refrigerants and refrigeration systems. Moreover, strict regulations such as F-gasregulation and Kigali Amendment forcing a phase down of many current widely used high global warming potential (GWP) refrigerants, i.e. R134a or R410A. Therefore, secondary refrigeration systems and their working fluids are expected to play a key role in order to minimize the refrigerant charge in the systems, reduce the indirect refrigerant leakages as well as increase the safety during operation.

    The aim of this thesis is to investigate the effect different additives to increase the flame point together with ethanol-based secondary fluids and validate their thermophysical properties by comparing them with reference values for pure ethanol water solutions. The study aims to design a new commercial ethyl alcohol-based product for GSHP system that could replace existing ones in the Swedish market and could workwith natural or flammable low GWP refrigerants.

    Different high flash point additives were tested such as 1-propyl alcohol, n-butyl alcohol, glycerol andpropylene carbonate. Thermophysical properties were investigated and a GSHP model in Excel was created in order to assess the energy performance of the resulted blends.

    After screening different blends and assessing the energy performance, glycerol as additive in low concentration seems to be the future for the ethyl alcohol-based secondary fluids because of its high flashpoint (160ºC) that will reduce the flammability risk associated to ethyl alcohol blends, the low viscosity (by 12% lower compared to pure ethyl alcohol blends) that help reduce pumping power by 4.5% compared topure ethyl alcohol blends. Moreover, ethyl alcohol and glycerol blend showed the lost in heat transfer coefficient by 4% lower compared to pure ethyl alcohol blends due to lower thermal conductivity compared to pure ethyl alcohol blends. Finally, it is a rather cheap and natural product which has no problem related to corrosion since ethyl alcohol and glycerol are less corrosive than water.

    Although, flash point test was not conducted so there is no data regarding the flash point, it is expected the flash point is increased due to the high flash point of glycerol compared to ethyl alcohol or other possible additives. Therefore, it is expected that the flammability risk associated to ethyl alcohol-based secondary fluids is reduced.

  • Mekler, Sandra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Alfredo, Ambre
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    The construction of identity: An urban study of the Centrums of Rinkeby, Tensta and Husby2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Stockholm Municipality has set inclusion at the core of its objectives for the city with its “Vision 2040: A Stockholm for Everyone” (Stockholm Stad, 2018). Acknowledging the divide between neighborhoods, the government has brought forward social sustainability as a key component to improve the fast-growing city. This research focuses on three of the most stigmatized neighborhoods of Stockholm: Rinkeby, Tensta, and Husby, where residents are predominantly of foreign background, to offer an alternative way of understanding inclusion. Specifically, this study looks into the public spaces at the center of these three neighborhoods in a comparative analysis of public life. The collaborative project presented here shows the importance of these centrums in supporting community life in the suburbs. Drawing from Setha Low’s research on public squares in Costa Rica, the following paragraphs suggest public space is not only produced by those who envision it, but also constructed by those who use it, through daily processes, behaviors, and habits. These observed patterns carry significance as they forge the character of a place, and address practices and emotions within a collective identity. The thesis puts emphasis on the dynamic nature of public space, the relationship between morphology and use, and the potential neighborhood centers have for becoming hubs of inclusion.

  • Fique, Simon
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    The production of space: An urban study of the Centrums of Rinkeby, Tensta and Husby2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Stockholm Municipality has set inclusion at the core of its objectives for the city with its “Vision 2040: A Stockholm for Everyone”. Acknowledging the divide between neighborhoods, the government has brought forward social sustainability as a key component to improve the fast- growing city. This research focuses on three of the most stigmatized neighborhoods of Stockholm: Rinkeby, Tensta, and Husby, where residents are predominantly of foreign background, to offer an alternative way of understanding inclusion. Specifically, this study looks into the public spaces at the center of these three neighborhoods in a comparative analysis of public life. The collaborative project presented here shows the importance of these centrums in supporting community life in the suburbs. Drawing from Setha Low’s research on public squares in Costa Rica, the following work suggest public space is not only produced by those who envision it, but also constructed by those who use it, through daily processes, behaviors, and habits. These observed patterns carry significance as they forge the character of a place, and address practices and emotions within a collective identity. The thesis puts emphasis on the dynamic nature of public space, the relationship between morphology and use, and the potential neighborhood centers have for becoming hubs of inclusion.

  • Bergdahl, Lina
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Women’s Perceived Safety on Public Transport Journeys: A Qualitative Study2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Women feel more fear than men in public space and when using public transport. This is an inequality in our society which limits women’s mobility and access to public goods. This study aims to qualitatively explore how women experience their public transport trips from a perceived safety perspective in a study of Gullmarsplan. Which elements women focus on during the trips and what they perceive as unsafe was explored, as well as what behaviors and strategies women use to manage their fear of crime. This was explored by first collecting travel diaries using a whole journey approach and then by narrowing the study down to performing walk-alongs in the walking environment at Gullmarsplan. The study found that women focus mostly on the social environment and that their reflections on the physical environment usually are related to perceived indicators of social incivilities and risk of victimization. Gullmarsplan was generally perceived as quite safe during the day but during evenings and nights most women avoided certain places which usually were secluded, difficult to survey or were perceived to attract dangerous others. Defensive adaptation strategies, mainly avoidance strategies and vigilance, were found to be the most commonly used safety strategies by women. Women’s fear of crime likely cannot be completely designed away in the physical environment but will require structural changes that promote gender equality in our society. With that noted, it is important that urban planners and designers are aware of how the physical environment affects women’s perceived safety. This study found that principles of CPTED generally made women feel safer, particularly important were good lighting and natural surveillance. Green spaces such as parks were found to often be avoided by women after dark. The geographical location and use of safety principles such as CPTED is thus especially important at such locations. Urban planners and designers have the power to shape public spaces that are accessible and safe. Public policies and design that promote equality in access to and use of public space is a feature of a more just democratic society.

  • Shammo, Johannes Hanna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Betti, Saad Faris Asaad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Skyddsutrustningen och logistikens påverkan på effektiviteten och olyckshändelserna2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The bachelor thesis was performed in cooperation with Erlandsson Bygg Öst. The purpose of this thesis is to find out how the personal protective equipment (PPE) and logistics increase the efficiency of the work and reduce the risk of accidents at building site. The project was to investigate the factors that impact the efficiency and activities some increase the risk for accidence. The study discusses only the PPE and logistics, because it considers as an important for building production. The motivation of this thesis is to look into the factors that can reduce the risk of accident in the future and make it more effective on the building method. In order to carry out the bachelor thesis there has been a combination of literature studies, questionnaires and interviews. The literature studies were in form of books and digital websites. And the interview performed with 2 managers. The questionnaires handed out to the worker that was at building site. After the work has been done was able to draw conclusion about which factors increase the risk of accidents and which factors affect the efficiency. The communication and APD-plan are the shortage of using of the PPE and problem in logistic is the factors that impact the efficiency and accidents. The recommendation has been presented to the company to raise awareness to increase efficiency and reduce the incidence of accidents.

  • Issa, Omar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Issa, Hadi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Logistiksamordningsprogrammet Myloc Construction2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    One of the biggest challenges in today's construction industry is the logistics issue, at an increasing, projects are being affected by logistic challenges and it is of great importance that these challenges are reviewed and addressed. More and more companies have started to address these challenges with the help of various logistics coordination tools to save time, get a better overall image and planning over the flow of materials, reduce damage to materials and more. The purpose of this thesis is to investigate whether the logistics coordination program Myloc Construction is an effective system to use in logistics management by examining how the program is perceived on three different projects. Through this study, the authors have reached the goal of whether the right choice of logistics method has been made for the three projects, at which kind of project Myloc construction will be used and whether it is a system that Veidekke should use for future projects. At present, a construction and renovation project is under way on three different housing bodies by Sergelhuset at Sergel's square where Veidekke, NCC and Zengun carry out the project in a turnkey contract in collaboration. All three contracts utilize the logistics coordination tool Myloc construction for their respective parts of the project. The study has been based on a combination of various research methods such as interviews, questionnaires, literature studies, observations and electronic sources. To get a deeper understanding of Myloc construction, nine people using the software have been interviewed. The survey was distributed to different users of the program to get a larger overall picture. Due to the size, location and complexity of the project, where several contracts work together, a logistics program is necessary. The program can be used for all types of projects but is most necessary for larger and more complex projects. Provided that Myloc continues to update its service both on the web and on the mobile phone, it is something that Veidekke should use in the future.

  • Bäckner, Caroline
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Vigert, Tobias
    Kan kostnadsbedömningar i tidiga skeden byggt på BIM utföras?2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today's society is at the forefront of a paradigm shift in digitization where cost-efficiency, productivity and digitalization interact. The Swedish construction sector has proven to have a low degree of development in digitization. Ottosson has shown that over 80% of all complications in construction projects are due to lack of communication. Svensk byggtjänst declares increasing costs for construction production and management by about SEK 60 billion each year. Basically, it is about how actors in the sector communicate among themselves, but also how information is handled digitally. A known concept in today's construction industry concerning information management and communication is BIM, "Building information model / modeling". The concept is about creating and utilizing precise digital models from construction projects. The aim is to obtain information from the digital model that is significant for the realization of the construction work and which then fulfills the BIM concept. The concept concerns information management, i.e. communication between different actors. ÅF-Infrastructure AB section "Byggekonomi – Rådgivning tidiga skeden" commissioned the authors of this master thesis to examine a specific method for cost assessments using digital models as a basis. The purpose of this thesis is to investigate the suggestion for approaches to cost assessments using digital models in order to develop the company's internal cost assessment tools. With this procedure, the right basis at the right stage within the early stage can contribute to increasing the quality of the adoption of financial decisions. The degree project is based on a qualitative method in the form of literature studies, interviews, participation in subject-specific seminars, observations of meetings and a quantitative method performed in order to simulate multi-dwelling housing projects. The methods have investigated the possibility of the information management systems Level Of Development and CoClass being available with a basis for cost assessment of the three stages in the early stages: the idea- feasibility study- and the program action stage. The study has shown two greater challenges. There is development potential both with regard to the classification system CoClass and the cost assessment tool Calc Frame. Regarding CoClass, it should above all be the classification system that informs the user about what ought to be contained under each level of information. It should not be up to the business community to interpret what information includes in each level in the system, this necessitate should be refined and clarified within the classification system itself. From a cost assessment point of view, it has not been possible to produce generic building complexes in Calc Frame. But since the tool is capable of handling several different construction works, these can thus be combined into specific and unique building works. Theoretically, the development of generic building complexes would be possible if the program were further developed. If this is considered desirable, then our assessment is that it is possible to further develop and apply the methodology on building complexes (with the same principle as the program is designed) to create generic complexes. Our study has shown that an economic evaluation in the early stages of the building process can be done with BIM. Whether ÅF-Infrastructure AB's updating of its internal cost assessment tool is compatible with digital models, the authors consider that the study has shown that the method used to increase the quality of cost assessments is compatible with the new classification system CoClass. The recommendation is therefore to update and develop cost assessment tools against the classification system CoClass.

  • Public defence: 2019-10-23 10:00 FA32, Stockholm
    De Luca, Eleonora
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Nonlinear Properties of III-V Semiconductor Nanowaveguides2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nonlinear optics (NLO) plays a major role in the modern world: nonlinear optical phenomena have been observed in a wavelength range going from the deep infrared to the extreme ultraviolet, to THz radiation. The optical nonlinearities can be found in crystals, amorphous materials, polymers, liquid crystals, liquids, organic materials, and even gases and plasmas. Nowadays, NLO is relevant for applications in quantum optics, quantum computing, ultra-cold atom physics, plasma physics, and particle accelerators. The work presented in the thesis is limited only to the semiconductors that have a second-order optical nonlinearity and includes two phenomena that use second-order nonlinearity: second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). Among the many options available, the investigation presented concerns gallium phosphide (GaP) and gallium indium phosphide (Ga0.51In0.49P), two semiconductors of the group III-V with the ¯43m crystal symmetry.

    However, some of the results found can be generalized for other materials with ¯43m crystal symmetry.

    In the thesis, the fabrication of GaP nanowaveguides with dimensions from 0.03 μm and an aspect ratio above 20 using focused ion beam (FIB) milling is discussed. The problem of the formation of gallium droplets on the surface is solved by using a pulsed laser to oxidize the excess surface gallium locally on the FIB-milled nanowaveguides. SHG is used to evaluate the optical quality of the fabricated GaP nanowaveguides. Additionally, a theoretical and experimental way to enhance SHG in nanowaveguides is introduced. This process uses the overlap of interacting fields defined by the fundamental mode of the pump and the second-order mode of the SHG, which is enhanced by the longitudinal component of the nonlinear polarization density. Through this method, it was possible to obtain a maximum efficiency of 10−4, which corresponds to 50 W−1cm−2. The method can be generalized for any material with a ¯43m crystal symmetry. Furthermore, SHG is used to characterize the nonlinear properties of a nanostructure exposed for a long time to a CW laser at 405 nm to reduce the photoluminescence (PL) of Ga0.51In0.49P. The PL was reduced by -34 dB without causing any damage to the nanostructures or modifying the nonlinear properties. The fabrication process for obtaining the nanowaveguide is interesting as well, since the fabricated waveguide in Ga0.51In0.49P, whose sizes are 200 nm thick, 11 μm wide and 1.5 mm long, was transferred on silicon dioxide (SiO2). This type of nanowaveguide is interesting for SPDC, since it satisfies the long interaction length necessary for an efficient SPDC. Finally, a configuration consisting of illuminating the top surface of a nanowaveguide with a pump beam to generate signal and idler by SPDC is presented. These fabricated nanostructures open a way to the generation of counter-propagating idler and signal with orthogonal polarization. By using a different cut of the crystal, i.e. [110], it makes possible to obtain degenerate wavelength generation, and in certain conditions to obtain polarization-entangled photons or squeezed states.

  • Banavase Shivalingappa, Anoop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Dhamal, Abhishek Chandrakant
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Analysis of Machining Performance using High pressure Minimum Quantity Lubrication (MQL)2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sustainability in manufacturing is a holistic approach. It is viewed in the context of entire manufacturing system of processes, products and raw materials rather than a single component. Metal cutting fluids which play a major role in all machining processes, should be managed efficiently to attain sustainability. One of the techniques by which this can be achieved is Minimum Quantity Lubrication (MQL). Using vegetable oil as a lubricant extracted from rapeseed and delivering this to the cutting zone at high pressures results in better penetration. Thus, forming a layer between cutting tool and workpiece. This reduces friction between the tool and workpiece and effectively reducing cutting temperature. This process contributes to overall increase in tool life and surface roughness of the machined surface. The main objective of this project is to study the tool life, chip morphology and surface roughness associated with the application of Vegetable oil as lubricant in minimum quantity at high pressure and comparing this with conventional flood cooling method. The experiment was carried out at Industriell Production (IIP) laboratory at Kungliga Tekniska Högskolan (KTH) in a CNC turning machine. The material used in this process is hardened steel (TooloxⓇ) provided by SSAB. The cutting Tool is supplied by Mircona AB and the vegetable oil is provided by Accu - Svenska AB. The experimental results unveiled convincing results with the usage of MQL at constant pressure of 12 bar at 7 mL/hr and 14 mL/hr respectively and varying pressures of 9 bar and 6 bar. The improvement in tool life and surface roughness which can be attributed in the order of outlet pressure is as follows:12 bar with dual coolant flow, 12 bar, 9 bar and 6 bar. The detailed explanation of this is provided in the results and discussion section. There is lot of scope for further study by increasing the pressure of MQL using additional boosters and applying this method to other machining processes such as milling, drilling and grinding. The study regarding the benefits of Vegetable oil as an MQL fluid could also reveal interesting results and positive effects to environmental and operator’s health.

  • Gustafsson, Robin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Fröjdendahl, Lucas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Machine Learning for Traffic Control of Unmanned Mining Machines: Using the Q-learning and SARSA algorithms2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Manual configuration of rules for unmanned mining machine traffic control can be time-consuming and therefore expensive. This paper presents a Machine Learning approach for automatic configuration of rules for traffic control in mines with autonomous mining machines by using Q-learning and SARSA. The results show that automation might be able to cut the time taken to configure traffic rules from 1-2 weeks to a maximum of approximately 6 hours which would decrease the cost of deployment. Tests show that in the worst case the developed solution is able to run continuously for 24 hours 82% of the time compared to the 100% accuracy of the manual configuration. The conclusion is that machine learning can plausibly be used for the automatic configuration of traffic rules. Further work in increasing the accuracy to 100% is needed for it to replace manual configuration. It remains to be examined whether the conclusion retains pertinence in more complex environments with larger layouts and more machines.

  • Kuthe, Sudhanshu
    KTH, School of Industrial Engineering and Management (ITM).
    Multimaterial 3D Printing of a mechanically representative aortic model for the testing of novel biomedical implants2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aortic stenosis is a serious cardiovascular disease that requires urgent attention and surgical intervention. If not treated, aortic stenosis can result in heart attack or cardiac arrest. Transcatheter Aortic Valve Replacement is a surgical technique that is used to treat aortic stenosis. Like all heart surgery, the procedure is difficult to perform and may lead to life-threatening complications. It is therefore important for a surgeon to be able to plan and rehearse the surgery before the operation to minimise risk to the patient.

    A detailed study was carried out to develop a 3D-printed, improved surgical tool for patient-specific planning and rehearsal of a Transcatheter Aortic Valve Replacement procedure. With this new tool, a cardiologist will be able better to understand a specific patient’s heart geometry and practice the procedure in advance. Computer tomography images were processed using image segmentation software to identify the anatomy of a specific patient’s heart and the surrounding blood vessels. Using materials design concepts, a polymer composite was developed that is able to mimic the mechanical properties of aortic tissue. State-of-art multi-material 3D printing technology was then used to produce a replica aorta with a geometry that matched that of the patient. An artificial aortic valve, identical to the type used in the Transcatheter Aortic valve replacement procedure, was then fitted to the replica aorta and was shown, using a standard test, to be a good fit with no obvious leaks.

  • Picard, Tom
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Inference and filtration of a hidden factor in credit risk2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Document is a Master Thesis report as part of the cycle of the ENSIMAG and KTH engineer. The internship linked to this report took place at Nexialog Consulting, Paris.This document deals with the inference and filtration by a counting process of a hidden parameter. The theory developed here is applied to Credit risk and specially to Migration Matrices of Rating.

  • Hemmingsson, Nils
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    On the dynamics of a family of critical circle endomorphisms2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis we study two seperate yet related three parameter-families of continuously differentiable maps from the unit circle to unit circle which have a single critical point. For one of the families we show that there is a set of positive measure of parameters such that there is a set of positive measure for which all points in the latter set, the derivative experiences exponential growth. We do so by applying a similar methodology to what Michael Benedicks and Lennart Carleson used to study the quadratic family. For the other family we attempt to show a similar but weaker result using a similar method, but do not manage to do so. We expound on what difficulties the latter family provides and what features Benedicks and Carleson used for the quadratic family that we do not have available.

  • Stiti, Karim
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Yape, Shih Jung
    KTH, School of Industrial Engineering and Management (ITM).
    Bid Forecasting in Public Procurement2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Public procurement amounts to a significant part of Sweden's GDP. Nevertheless, it is an overlooked sector characterized by low digitization and inefficient competition where bids are not submitted based on proper mathematical tools. This Thesis seeks to create a structured approach to bidding in cleaning services by determining factors affecting the participation and pricing decision of potential buyers. Furthermore, we assess price prediction by comparing multiple linear regression models (MLR) to support vector regression (SVR). In line with previous research in the construction sector, we find significance for several factors such as project duration, location and type of contract on the participation decision in the cleaning sector. One notable deviant is that we do not find contract size to have an impact on the pricing decision. Surprisingly, the performance of MLR are comparable to more advanced SVR models. Stochastic dominance tests on price performance concludes that experienced bidders perform better than their inexperienced counterparts and companies place more competitive bids in lowest price tenders compared to economically most advantageous tenders (EMAT) indicating that EMAT tenders are regarded as unstructured. However, no significance is found for larger actors performing better in bidding than smaller companies.

  • Public defence: 2019-10-25 14:00 F3, STOCKHOLM
    Bakyayita, Grace Kizito
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering. Makerere University, Kyambogo University.
    Batch Sorption Studies of Aqueous Cadmium and Lead from Contaminated Water onto Selected Biosorbents2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Groundwater, wastewater, surface runoff and surface water samples from Lake Victoria basin, Uganda was assessed for trace metals contamination. Untreated, base-treated and peroxide-treated biosorbents from Albizia coriaria, Coffea canephora, Cyperus papyrus, Erythrina abyssinica and Musa spp were investigated for removal of selected trace metals from contaminated water in batch studies. The assessed shallow groundwater and surface water was contaminated with iron and manganese. Selected speciation studies using Visual MINTEQ showed that in leachates from Municipal dumpsites 74% of the metal ions were bound to DOM, 13% were free ions and 13% were in inorganic forms moreover for urban streams 37% of the metal ions were bound to DOM, 44% were free ions and 19% were in inorganic forms. The metal levels in surface water, landfill leachate and surface runoff showed elevated levels and revealed increased risks to environmental health. Risk analysis based on the Swedish EPA showed that varied risks of negative effects in 30% – 76% of the sample sites ranging from high to increased risk in surface water whereas the results from Bio-met tool showed potential risk to toxicity effects of Cu2+, Ni2+, Zn2+ and Pb2+ in 15.3% - 30.8% surface water samples and 8.3% - 62.5% groundwater samples. Batch sorption studies revealed that the optimal conditions for Cd2+ and Pb2+ ions uptake were; pH 3.5 – 5.0 for contact time 3.0 – 3.5 hours and biosorbent dosage 10 – 12.5 g/L. Base-treated biosorbents showed 10 – 17 % sorption enhancement for Cd2+ ions and 1.6 – 2.3 % uptake reduction for Pb2+ ions. The biomass negative potential for binding base cations was in the order; Musa spp. > A. coriaria > E. abyssinica and base treatment reduced DOC leaching from biosorbents in the order; E. abyssinica > A. coriaria > Musa spp. Speciation studies showed that more ions were complexed to DOC in solutions at various pH levels. The maximum sorption intensities for both Cd2+ and Pb2+ ions uptake onto biomass occurred for low initial metal concentration; 5 mg/L. Freundlich model best fitted data for Pb2+ ions ions uptake whereas Temkin model fitted the sorption data for Cd2+ ions onto both treated and untreated biomass. For peroxide treated biomass, the maximum sorption efficiencies for both Cd2+ and Pb2+ ions were between 95.2 – 98.7% for C.canephora, 79.9 – 92.2% for Musa spp. and 42.0 – 91.3% for C.papyrus in non-competitive media and 90.8 – 98.0% for C.canephora, 56.4 – 89.3% for Musa spp. and 19.5 – 90.4% for C.papyrus in competitive media. The Langmiur model fitted non-competitive sorption data with 0.769 ≤ R2 ≥ 0.999 and the Freundlich model fitted competitive sorption data with 0.867 ≤ R2 ≥ 0.989. The pseudo second order kinetic model fitted the sorption data for Cd2+ and Pb2+ ions for untreated, peroxide treated and base treated biomass with 0.917 ≤ R2 ≥ 1.000. The sorption of trace metals was a complex potentially monolayer chemisorption with heterogeneous surface properties exhibited. In competitive sorption, sorption suppression effects observed were greater for Cd2+ than Pb2+ ions. The comparative studies on sorption performance presented agreement and no significant difference between the untreated and base treated biosorbents. 

  • Hamadi, Farah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Wallin, Viktor
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Förseningstimmar på mötesseparerade 2+1-vägar: Hur förseningskostnaden påverkas av ombyggnad till 2+2-väg i relation till investeringskostnaden2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    From the late 1990s, a large part of the non-separated 13-meter-wide roads have been reconstructed into meeting separated roads, where traffic in each direction is separated by a middle strip. Meeting separated roads have been a very successful project for road safety and have contributed to a large reduction in severely injured and casualties in traffic. There are many meeting separated roads in Sweden. In the case of accidents on 2+1-roads, it becomes difficult for the traffic to turn around on the road, which leads to a stop and makes it difficult for the emergency services and tow trucks to reach the scene of the accident. These accidents lead to delay hours and, in turn, to community costs. This thesis is written for the Swedish Transport Administration to review 2+1 roads in the Swedish Transport Administration’s Region East. The report produces and compares the reduction of delay costs after rebuilding a road from 2+1- to 2+2-standard, the report also presents and compares the delay cost with the investment cost for the reconstruction. This study is based on literature studies, analysis of data from the “Traffic Management”, internet-based programs and through the use of Microsoft Excel for calculating delay hours and -costs for selected roads and routes. The result of the report shows whether it is worth investigating in a reconstruction from 2+1- to 2+2-road from delay cost perspective. This is presented through a general comparison per Scandinavian mile of 2+1-road based on roads 50, 55 and 56 in the Swedish Transport Administration’s Region East. The report also contains an analysis of the five most affected accident sites on the E18's 2+1-routes. The analysis of these accident sites showed that all five were between Köping and Västerås in Västmanland county.

  • Mohammadnia, Hamzeh
    KTH, School of Electrical Engineering and Computer Science (EECS).
    IoT-NETZ: Spoong Attack Mitigation in IoT Network2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The phenomenal growth of the Internet of Things (IoT) and popularity of the mobile stations have rapidly increased the demand of WLAN network (known as IEEE 802.11 and WiFi). WLAN is a low-cost alternative of the cellular network and being an unlicensed spectrum to build the master plan of embedding the Internet in everything -&-anywhere. At the same time, monitoring the number of IoT and WiFi-enabled devices across residential and enterprises is not trivial. Therefore, future WiFi network architecture requires an agile management paradigm to provide internal support and security for WiFi networks.The operation of IoT and mobile device applications relies on scalability and high-performance computing of clouds. Cloud computing has completely centralized the current data center networking architecture and it provides computation-intensive, high-speed network, and realtime responses to the requests of IoT. The IoT-to-cloud communication is the essence of network security concerns and it is in grievous need of constant security improvement along the inter-networking. Based on the number of researches and analysis on generated traffic by IoT, it has been observed there are the significant number of massive spoofing-oriented attacks targeting cloud services are launched from compromised IoT.On the basis of reviewing prior researches on mostly-conducted network attacks by IoT, there is a challenging and common characteristic which has been frequently utilized in the numerous massive Internet attacks, known as spoofing. This work will survey the existing proposed solutions which have been deployed to protect both traditional and softwarized network paradigms. Then, it proposes the approach of this work that enables IoT-hosting networks protected by employing Software-defined Wireless Networking (SDWN) within the proposed model to mitigate spoofing -oriented network attacks. In addition, the proposed solution provides the environmental sustainability feature by saving power consumption in networking devices during network operation. The practical improvement in the proposed model is measured and evaluated within the emulated environment of Mininet-WiFi.

  • Franzén, Henny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Elmondt Nilsson, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Akustiska värden i platonkonstruktioner: Minimera lågfrekvent buller i skolmiljöer2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study highlights the intensity and the extent of sound levels produced by a so called floating floor. The study has closely observed floor constructions made of Platon mat in order to detect the acoustic factors and how they are manifested when stepping on the floor. The study also compares the results of step- and drum sound levels with Granab constructions, another type of floating floor, as well as how the Platon construction stands in relation to the statutory guide values. This study has focused on how the sound from a Platon floor is perceived in an objective and a subjective perspective, because in some cases measured values do not correspond to the actual experience. Measurements that have been carried out give an idea of how to design floors and what type of material should be used to obtain the most favorable sound level possible. Overall, this study shows that the design of the floors can, to a large extent, minimize step- and drum sounds. This knowledge can be of great use when designing a floating floor since it has been shown that high sound levels in the lower frequencies affect, among other things, our abilities of learning and concentrating.

  • Cleve, Oscar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Gustafsson, Sara
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Automatic Feature Extraction for Human Activity Recognitionon the Edge2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis evaluates two methods for automatic feature extraction to classify the accelerometer data of periodic and sporadic human activities. The first method selects features using individual hypothesis tests and the second one is using a random forest classifier as an embedded feature selector. The hypothesis test was combined with a correlation filter in this study. Both methods used the same initial pool of automatically generated time series features. A decision tree classifier was used to perform the human activity recognition task for both methods.The possibility of running the developed model on a processor with limited computing power was taken into consideration when selecting methods for evaluation. The classification results showed that the random forest method was good at prioritizing among features. With 23 features selected it had a macro average F1 score of 0.84 and a weighted average F1 score of 0.93. The first method, however, only had a macro average F1 score of 0.40 and a weighted average F1 score of 0.63 when using the same number of features. In addition to the classification performance this thesis studies the potential business benefits that automation of feature extractioncan result in.

  • Celik, Engin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Bohman, Tobias
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Leveransstörningar i produktion: En undersökning av JM:s leveransprecision och arbetsledarnas nyttjande av digitala verktyg2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The logistics and delivery process in the construction business has always been a problematic area. Due to the fact that building projects take place in project form and production is site-based, it becomes difficult to create standardized logistics flows. This means that effective methods must be applied in order to achieve a successfull logistics process. One of these methods is the implementation of digital tools. Through digital systems that facilitate communication and information transfer between all parties, construction companies aim to improve construction logistics. However, digitization in the construction industry is still a developing area and the usage of digital tools on construction sites is still low today. This report examines delivery disturbances in production and the frequency of reported delivery disturbances in JM's digital systems. The purpose of this thesis is to highlight the problems surrounding JM's digital tools and at the same time improve the usage. Another purpose is to find out the number of unreported delivery disturbances. The study is limited to four projects south of Stockholm and the field study is performed in four weeks. The survey that is ongoing on these projects is divided into quantitative and qualitative methods. Interviews with supervisors are carried out on the projects and in parallel with this, own statistics are also made regarding the delivery precision. In addition, JM's digital systems are also being examined. This report includes the following digital systems: avropssystemet, inköpssystemet and the BI-system. The field study results showed that the delivery precision was 69%. In contrast, JM's statistics reported 89%. The difference and thus the unreported delivery disturbances was 20 percentage points. The supervisors felt that the complexity of avropssystemet was a major cause of the low usage. The field study also showed that the following factors contributed to the low use of the systems: • The lack of time • The size of the delivery defect • The suppliers' lack of knowledge regarding avropssystemet • The new design of inköpssystemet In order to achieve a higher delivery precision at the construction sites, JM's digital systems need to undergo changes and become more user-friendly. The systems must be designed and adapted to the supervisors. This, in turn, will mean that JM can collect more data centrally and gain better control.

  • Heiska, Mirjami
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Assessing the environmental impacts of a tool rental service from Husqvarna using Life Cycle Assessment  Confirmation that the opposition is completed2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To decouple ever-increasing production and the related environmental impacts, collaborative use of products and product-service-systems including rental services can help to intensify the use of products during their designed lifetimes. While these approaches present potential to decrease environmental impacts compared to traditional linear product sales, they need to be assessed with a holistic scope to avoid counterintuitive trade-offs.

    This study evaluates the potential environment impacts of Husqvarna’s tool rental service with a hypothetical case example from Stockholm, Sweden. The objectives are to analyse the potential environmental impacts of the rental service, to identify hotspots for improvement and to compare the potential impacts of the rental system to a sales alternative. The annual service of one electric chainsaw is analysed using Life Cycle Assessment (LCA) methodology with different user scenarios. The potential impacts are analysed for global warming potential, fossil and mineral resource scarcity, marine ecotoxicity and human carcinogenic and non-carcinogenic toxicity.

    The analysis for the rental system shows that user transport back-and-forth to the rental service is a key contributor to all the environmental impacts analysed, if done by private cars. The comparative results to sales business model indicate that while the rental service can help to reduce the potential impacts in mineral resource scarcity and toxicities due to the lower number of products needed, the user transport may outweigh the potential improvements in global warming potential and fossil resource scarcity, depending on the distances and modes of transport. Different scenarios illustrate that the results are however sensitive to the assumptions made.

    Based on the results, it can be recommended to optimally place the service close to the users and to take efforts to reduce user transports around the service, to reach the environmental potential of the service. The sensitivity analyses also indicate the importance for accounting detailed data for LCAs for product-service-systems and covering the service holistically in system boundaries. Further studies on user behaviour are suggested to reach more robust analyses on consumer services, to cover also potential rebound effects.

  • Berglund, Johan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Analys av olika positioneringssystem för Trafikförvaltningens järnvägsbanor2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Positioning systems have a vital role in securing safe movement of trains. There are many differenttypes of positioning systems. This thesis is about how axle counters, communications-based traincontrol (CBTC) and different kinds of track circuits operate. It also contains an analysis of AC-trackcircuits and axle counters with RAMS-parameters (Reliability, Availability, Maintenance and Safety)as guide points to make a conclusion of what type of system that best suits for Stockholm PublicTransports railway tracks. Through interviews with experienced persons within the railway industryin Stockholm knowledge of pros and cons of different systems was obtained. A fault tree analyses(FTA) was made for axle counters and track circuits to visualize potentially hazardous situations.Failure statistics were produced to show failure frequency for one track with axle counters and onetrack with track circuits. A clear result was not shown but it can be concluded that sources of failurethat are prone to track circuit systems can be avoided using axle counters. What became evident isthat the management need to standardize to a fewer amount of different positioning systems. Itwould make it easier to find available personnel with the required skills for doing maintenance. Thiswould also have a benefit when securing maintenance supplies.

  • Pham, Trang A.T.
    et al.
    Schwerdt, Julian G.
    Shirley, Neil J.
    Xing, Xiaohui
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Srivastava, Vaibhav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Little, Alan
    Analysis of cell wall synthesis and metabolism during early germination of Blumeria graminis f. sp. hordei conidial cells induced in vitro2019In: The Cell Surface, ISSN 2468-2330, Vol. 5, p. 100030-Article in journal (Refereed)
    Abstract [en]

    As an obligate biotroph, Blumeria graminis f. sp. hordei (Bgh) cannot be grown in an axenic culture, and instead must be cultivated on its host species, Hordeum vulgare (barley). In this study an in vitro system utilizing n-hexacosanal, a constituent of the barley cuticle and known inducer of Bgh germination, was used to cultivate Bgh and differentiate conidia up to the appressorial germ tube stage for analysis. Transcriptomic and proteomic profiling of the appressorial germ tube stage revealed that there was a significant shift towards energy and protein production during the pre-penetrative phase of development, with an up-regulation of enzymes associated with cellular respiration and protein synthesis, modification and transport. Glycosidic linkage analysis of the cell wall polysaccharides demonstrated that during appressorial development an increase in 1,3- and 1,4-linked glucosyl residues and xylosyl residues was detected along with a significant decrease in galactosyl residues. The use of this in vitro cultivation method demonstrates that it is possible to analyse the pre-penetrative processes of Bgh development in the absence of a plant host.

  • Bommakanti, Hemanth Ram Kartik
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Impact of Time Synchronization Accuracy in Integrated Navigation Systems2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Global Navigation Satellite System/Inertial Measurement Unit (GNSS/IMU) Integrated Navigation Systems (INS) integrate the positive features of GNSS and IMU for optimal navigation guidance in high accuracy outdoor navigation systems, for example using Extended Kalman Filter (EKF) techniques. Time synchronization of IMU data with precise GNSS based time is necessary to accurately synchronize the two systems. This must be done in real-time for time sensitive navigation applications such as autonomous vehicles. The research is done in two parts. The first part is the simulation of inaccurate time-stamping in a single axis of nonlinear input data in a gyroscope and an accelerometer, to obtain the timing error value that is tolerable by a high accuracy GNSS/INS system. The second part is the creation of a real-time algorithm using an STM32 embedded system enabled with FreeRTOS real-time kernel for a GNSS receiver and antenna, along with an IMU sensor. A comparative analysis of the time synchronized system and an unsynchronized system is done based on the errors produced using gyroscope and accelerometer readings along a single axis from the IMU sensor, by conducting static and rotational tests on a revolving chair.The simulation concludes that a high accuracy GNSS/INS system can tolerate a timing error of up to 1 millisecond. The real-time solution provides IMU data paired with updated GNSS based time-stamps every 5 milliseconds. The timing jitter is reduced to a range of ±1 millisecond. Analysis of final angular rotation error and final position error from gyroscope and accelerometer readings respectively, indicate that the real-time algorithm produces a reduction in errors when the system is static, but there is no statistical evidence showing the reduction of errors from the results of the rotational tests.