1234 1 - 50 of 200
rss atomLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
  • Säving, Nils
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Rening av PFOS från lakvatten på Tveta avfallsanläggning2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The waste treatment plant of Telge Återvinning in Tveta have old landfills which produces leachate and processwater. The leachate is transported with pumps to the water treatment plant Himmerfärdsverket, Syvab. The water treatment plant has a REVAQ-certificate since 2009 and the requirements to keep the certificate have become tougher. Perfluorooctanesulfonate (PFOS) is one of the substances in the produced leachate. The content limit for that substance has now been decreased to 15 ng/l which means that Telge Återvinning must lower their PFOS content in their leachate. To do so they’ll need a PFOS removal efficiency of 90% based on their current content value. The leachate also contains lots of particles which needs to be removed if the desired removal efficiency is to be reached.

    PFOS is a none-reactive, bio-accumulative, substance which is also toxic. There’s only a few treatment methods that can be used for the removal of this substance in liquid matrixes because of its none-reactive nature. The point of this report has been to highlight these methods and evaluate them based on their possible usage as a treatment method for the leachate at the waste treatment plant. The information for these methods have been gathered through literature studies and interviews.

    The available methods which were able to achieve the desired removal efficiency were the reverse osmosis and the nanofiltration, the ion exchanger, the granular active carbon filter and powdered active carbon. From these available methods the granular active carbon filter was thought to be the most suited method for treating the leachate. The most suited method was decided based on its operation cost and familiarity with prior PFOS treatment plant. The treatment process for the particle removal couldn’t be fully decided without field studies. Although flocculation was decided to be the primary step in the treatment process.

  • Fjordefalk, Vera
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Reningsmetoder för dagvatten innehållande mikroplaster från konstgräsplaner2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The number of artificial turfs in Sweden has increased significantly since the year 2000. Today there are about 1255 outdoor pitches made from artificial turf and the annual increase is estimated at 100 pitches. Artificial turfs provide many benefits for sporting activities such as longer game seasons and more playing hours. To gain characteristics as close to natural turfs as possible, infill is used on top of the artificial grass. The infill is usually made out of styrene-butadien rubber (SBR), ethylene-propylene-diene-monomer-rubber (EPDM) or thermoplastic estalomer (TPE). However, there is also organic alternativs made from cork or coconut. Since the filling materials mostly consist of plastic polymers, some environmental concerns have been raised in the connection of the use of infill.

    The manufacturing size of infill is between 2-3 mm and is thereby classified as primary microplastics. The Swedish Environment Institute performed a study to map the sources of microplastic emissions to the marine environment. The study concluded that artificial turfs was the second largest land-based source of microplastic emission. The conclusion was based on the suggested annual amount for refill of infill for a full-size pitch. The amount of microplastics ending up in the sea, lakes and streams was not answered in the study, as it would require a more extensive mapping of routes. Former studies have shown that a certain amount of infill ends up in the stormwater wells which is placed around the turfs to prevent water collection.

    In order to prevent continued spreading via stormwater wells out to marine environments, treatment methods for stormwater runoff from artificial turfs has been requested.The objective of this study is to identify suitable methods for treatment of stormwater containing microplastics from artificial turfs. To find out what methods are used today, four manufacturers of granulate traps and filters were contacted. The municipalities that have installed or planned to install any of the stormwater treatment methods was also contacted to get an understanding of how these methods works in practice. From the study it is apparent that the development of treatment methods mentioned is in an early stage where efficiency is not tested for any of the methods. In order to determine what a suitable stormwater treatment method is in this case, further studies on how water flows vary between different pitch designs and surrounding surfaces are required. In this study the amount of microplastics found in the stormwater wells is solely based on ocular inspection and often described as "small" by the interviewees. To determine the exact amount of microplastics that can occur in stormwater wells, it would be necessary to weigh the microplastics found in the wells on every single plant. Because of differences in maintenance routines and depending on the existence of available surfaces for storage of snow and infill, the amount of microplastics found in the wells varies.

    The size of microplastics found was estimated to be of manufacturing size (2-3 mm). However, microplastics can become very small, down to 1 μm and hard to see with the naked eye. Further studies are recommended to set up a grain size distribution curve which can be used to manufacture the mesh in a reasonable size. The small sizes of microplastics makes it unreasonable to expect a purification degree f 100%, the mesh size would make it impossible for water to flow through. This calls for establishing guidance values for microplastics in stormwater.

    In order to establish guidance values and carry out necessary studies to develope the existing methods, a better cooperation between institution and trade and industry is needed. A method can be considered to be suitable for microplastics if the largest percentage part by weight of microplastics is caught. The suitability of the current methods cannot be judged until this is determined.

  • Cömert, Engin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Utvärdering av karboniserad LDPE som egenskapsförbättrande tillsats i nya LDPE-filmer2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Previous research has shown that with the assistance of a specially formed microwave oven you can degrade low density polyethylene (LDPE) to chemicals with more value, so this project will try to reform plastic waste (LDPE) to a product with more value.

    Being able to recycle plastic is a question that has grown these past years and is still growing. As things stand there is an interest in being able to produce plastics that can be recycled. Because plastics lose some of their mechanical properties every time they are heated the companies who produce them find it easier and cheaper to just use new plastic. Therefore, to be able to produce a plastic which does not lose its mechanical properties is something that is being strived for. Carbon dots is a new kind of nanomaterial that has fascinating properties and research on it and its properties has been done during the last 10 years. During this project the main focus will therefore be to evaluate whether LDPE can be carbonized to carbon dot like materials and whether addition of these affects the mechanical properties of new LDPE products.

    By using the special microwave, the synthesis of carbon dots was successful. In addition, solid particles we gained from LDPE. The structural properties of the carbon dots and solid particles were analysed by using FT-IR, NMR and XRD. There was also an analysis on the particle sizes which was done by using DLS and morphological evaluation which was performed by SEM. The synthesized particles were also put into TGA to evaluate their thermal stability. The synthesis was successful, and you could see a change in the particles structure because new functional groups could be found by using FT-IR, NMR and XRD. The particle size was also measured, and the consensus was that the particles were coarse and not that homogenous.

    Making of the composites with the carbon dots and solid particles is also something that was successfully done. The composites contained 0.5 wt-% of synthesized carbon dots and 99.5 wt-% of LDPE powder and another one where 2.5 wt-% of synthesized carbon dots was mixed with 97.5 wt-% of LDPE powder. The solid particle composites were created by mixing 5 wt-% and 10 wt-% solid particles mixed with 95 wt-% and 90 wt-% of LDPE powder.

    The mechanical properties were analysed with a tensile testing machine, the result that was retrieved from the machine was that the films made of the composites with DP gave a stiffer material than the film made only by LDPE. The composite films with FP gave a much higher modulus than the other films made by addition of DP. The results show that the films with FP were also a lot stiffer than the film with only LDPE. The conclusion is that you can use this method to create a material that is stronger and stiffer.

  • Bujak, Klaudia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Kartläggning av analysmetoder för mikroplaster från konstgräsplaner2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The presence of microplastics in marine and sedimentary environments is a relatively new problem. Presently, there are no clear standards to which methods that should be implored with sampling, treating and analysing microplastics. Because of this, some troubles occur when estimating field concentrations and comparing microplastics flow and composition.

    Artificial turf plants have been considered to be the second largest source of microplastic emissions in Sweden. Pre-emptive measures have been taken in several regions in Sweden in order to decrease spreading of microplastics. Because of this, it is important to be able to measure the amount of microplastics in marine environment and sediment in order to monitor how it changes when using different methods.

    The purpose of this study is to increase the knowledge of the methods available and suitable for sampling, treatment and analysis of microplastics from artificial turf in water and sediment environments.

    The aim is to provide a suggestion of measurement methods that may be suitable for analysis of microplastics from artificial turf in Ältasjön.

    In order to clarify the importance of a holistic view of the microplastics, an analytical chain has been developed. It is regarded to be a useful tool in order to further the develop a standardized method for the entire analytical process, from sampling to interpretation of results. This analytical chain is comprised by four major steps: sampling, laboratory preparation of samples, analysis and interpretation of the results.

    Sampling will be of crucial importance for the evaluation of final results, because the sampling efficiency has direct impact on the content of the sample which will proceed to the analysis. There are no standardized procedures for sampling of microplastics with regard to location, sampling equipment, volumes and sampling time. This results in a limited comparability with previous studies.

    The treatment is usually comprised of volume reduction, density separation and chemical or enzymatic purification. These treatment methods need to be adapted in regard to the expected content of the sample and the chosen analytical method.

    Analysis of microplastic could be done with the help of optical, spectrophotometric or chromatographic methods. The optical analysis enables to monitor the particles physical properties such as size, shape, colour and degree of degradation. The spectrophotometric and chromatographic methods provide information about chemical composition, polymer type and the additive content of microplastics. These methods investigate different properties and therefore they result in different answers. Each technique should be thought of and analysed from the information that is provided. Also, all analytic methods have different detection limits. These detection limits vary between and it is important to take into consideration when choosing the correct analytical method.

    If different studies use the same methods to gain the desired information, the results will be more easily compared. The combined results will help to complete more of the missing information and improve the monitoring of microplastics spreading to marine environments and sediment. Provided that all studies not only follow the same methods but also the same analytical chain from sampling to analyzing the results.

    From the information and knowledge that was gathered, it is expected that Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM-EDS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) has the biggest potential to efficiently measure microplastics from artificial turf in water environment and sediment. Both SEM-EDS and ICP-MS makes it possible to detect all types of granulate and plastic straws from artificial turf even when the grain is between 10 and 20 mm. Further studies of these methods are recommended to build a reference library for each respective method and to find a working standard method when analysing microplastic from artificial grass.

  • Aldabbagh, Zina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    En undersökning av Rönningesjöns miljötillstånd, särskilt när det gäller metaller2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lake Rönningesjön lies in a geological fault (a crack) and it is affected by the clay in the surrounding fields. The pH-values lie within the interval 7.1–7.7. The lake is also impacted by the roads around the lake. The incoming water contains large amounts of road salt. From the cars also large amounts of metal ions are transported by the incoming storm water. In this project copper, chromium and lead are measured. Most of the metals in the lake pass through the wetland at Löttingelund in one end of the lake and flows through the lake to the outlet, which delivers the metal ions into Hägernäsviken, which is a part of the Baltic Sea. However, a part of the metal ions are precipitated in the lake. The concentrations of metal ions in the lake water are too high. Metal ions are also stored in the sediments. Special dams should be constructed to remove particle bound metals from the storm water, by sedimentation.

  • Panja, Manjusha
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Sustainability Integration in the Fashion Retail Industry2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sustainability has gained prominence from past couple of decades, the fashion industry is most polluting industries in the global. This research is to explain the importance of sustainability integration in the fashion industry. The research methodology applied is first, it provides literature review examining books and articles pertaining to environmental and social responsibility in fashion industry from past decade. Secondly, the case study on H&M Group and interviewing end consumers of fashion. The results to demonstrate the importance of sustainability in the fashion industry and how fashion retailers play a key role and responsibility for enabling sustainability in the whole supply chain.

  • Liu, Wen
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    On Ethicality of Multi-level Marketing Schemes on Wechat Platform in Mainland China2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Multi-level marketing schemes (MLMs) is one of the fastest growing types of business in the world. Especially in China, with the development of e-commerce and social network application, increasingly people start doing business for MLM companies in social network platform. However, there are few academic articles have been written about the ethicality of MLMs on social media application in China. What surprising is, even in China, the ethical issue of MLMs on Wechat is controversial. Among the ordinary person, MLMs sometimes have been accused of being pyramid schemes, which is illegal in China. Besides, many people complain that some of their friends sell products on Wechat, which make them uncomfortable and sometimes be pressured to buy it. This research explores the nature of MLMs and the ethical issues of it. It argues that MLMs on Wechat in China posed some unique ethical issues and attempts to search for the solutions for them.

  • Jonsson, Oscar
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    The impact of public funding: A qualitative study analyzing the Vinnova program VINN-verifiering2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this report was to investigate how the innovation process impact commercialization of innovations with funding. This was accomplished by conducting qualitative interviews, an extensive literature review and a review of corporate documents. The empirical data was that was used to address the purpose was gathered from the program VINN-verifiering at Vinnova, Sweden’s innovation agency. The program was expected to help business concepts to become commercialized, or come closer to commercialization. The intention of the report was to highlight the importance of funding for business concepts by analyzing the program VINN-verifiering. It was also intended to provide insight into how the funding impacts innovations. The most important findings were that the public funding during the innovation process overall had a positive impact on the commercialization. The funding was not enough to reach commercialization in any case. However, this was expected as the funding was limited. The public funding during the innovation process did, however, shorten the time to commercialization. It made it also possible for them to reach as far as they did, without funding more projects would still be in a scientific research phase.

  • de Abreu Almeida, Fernando
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    The effect of bolt clearance and tolerances on the shear resistance of bolted connections subjected to uni-axial loading: A parametric study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis was to investigate the effect of clearance and tolerance in bolted joints when there is a mismatch between the bolt holes. A parametric study with seven different cases was analyzed in this project; four double bolt configuration and three triple bolt configuration, with variation of the size of the bolt hole misalignment, the diameter of the bolt and the thickness of the plates. All analyses were performed with the aid of the FEM commercial software Abaqus, all the models were modelled with 3D brick elements.

    Despite bolted connections being subject of several investigations, no study about this matter for structural engineering purposes had been performed before.

    The results indicate that for connections with a low number of bolts a misalignment of the bolt clearance can cause a serious reduction in the ultimate bearing capacity of a joint and it indicates that the Eurocode 1993 1-8 might be overestimating the ultimate bearing capacity for some cases.

  • Johansson, Gustav
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Wilhelmsson, Sofie
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Digital Maturity & Operational Performance: A case study in the supply-chain of the Scandinavian FMCG industry2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Manufacturing companies are currently experiencing a digital transformation pressure as focus on concepts such as Industry 4.0 are growing. Industry 4.0 a concept inheriting, among other technologies, IoT, Cloud manufacturing and advanced analytics. The digital transformation and digitalisation of manufacturing may provide performance improvements. For example, in Supply chain functions, due to increased information sharing and possible performance improvements in forecast accuracy and deliverer accuracy. However, many companies are uncertain regarding how digital transformation best could be approached. An increasingly digital supply chain will increase the complexity of the organisation and the first step of any such transformation is to understand current capabilities. In this study we applied and, propose, the usage of a digital maturity framework, including a questionnaire, which is academically robust, has high level of transparency regarding the questionnaire, and are measuring all corporate functions. The digital maturity model is built on 3 dimensions, Strategy & organisation, Smart business processes and Smart product & services, 3 sub-dimensions and 13 associated fields. The framework thereby assesses all necessary enablers for digital transformation and provide guidelines for companies regarding what dimensions that are lagging and potentially are hindering a digital transformation. The framework was adapted and applied in the Scandinavian FMCG industry. By assessing 3 companies within the same corporate group which enabled triangulation with interviews to ensure validity provided a deeper understanding of the challenges in digitalisation and level of digital maturity in the Scandinavian FMCG industry were obtained. The results indicate that the major factor causing the low level of digital maturity within the Scandinavian FMCG industry were due to insufficient Strategy & Organisation mostly caused by a lack of strategic partners. The study concludes that competence and knowledge regarding how to approach digital transformation are the major challenge. In order to avoid develop all capabilities internally it is therefore important to source strategic partners. In addition, this study explored certain KPI’s that, according to the SCOR-model, are of great importance for operational performance. The SCOR-model were used since it is an established framework. The KPI’s for each of the participating factories were presented in relation to the digital maturity score within the associated field of production, procurement & logistics. Although no claims regarding causal relationships between digital maturity are made, the study proves the importance of connecting digital maturity to KPI’s in order to provide tangible benefits.

  • FRANK, ERIK SIMON
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Corporate Innovation: A Case Study of the Corporate Incubation Process2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Public defence: 2019-01-25 10:00 4301 Kollegiesalen, Stockholm
    Pham, Cong-Toan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Assessment of energy storage systems for power system applications based on equivalent circuit modeling2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Climate change triggered the rethinking of our current energy system. A restructuring is necessary and in progress with the goal to improve our energy supplychain in efficiency and sustainability. This has led to the increased use of renewable energy sources such as solar and wind power. In 2017 wind power surpassed all other sources, including oil, nuclear, coal, except gas in terms of total installed capacity. Renewable energy sources became an integral part in our energy systemand will continue to grow in the future. However, what is often forgotten ist hat these sources introduce high variability in the provision of power. Variability implies a lack of control over the availability of electricity, which seldom matches with the concurrent demand. Energy storages have been highlighted as a viable solution in managing arising imbalances and maintaining the security of supply. Nevertheless, numerous technologies and application possibilities exist, each unique in their characteristics and requirements. Not every energy storage works in every situation, which naturally raises the question: How can we choose the optimal storage for any application?

    To answer this question we developed an unified model approach for all energy storages based on the equivalent circuit model. The key idea is to provide a direct way of comparing and assessing energy storages, i.e., by simulating and analyzing their performances for different applications. Differences in performance become visible in investigating the dynamic behavior. We proposed a general model, which effectively represents energy storages of different types (electrical, mechanical, hydraulicetc.) and includes their main characteristics (also non-linearity). Secondly, the proposed models have been validated through an experimental setup to test energy storages under changing operations. Subsequently, a sizing routine has been implemented to optimally size an energy storage system for any type of application. Based on this approach the energy storages can be easily compared and important key parameters such as efficiency, rated power, energy capacity etc., can be derived. Finally, the proposed models and methods are applied to various power system applications. A suitability index is introduced to measure the qualification of an individual energy storage for the selected applications. Alternatively, an evaluation method based on fuzzy logic has been explored. Both suitability index and fuzzy logic can effectively determine and rank the suitability of energy storages.

  • Gaborit, Mathieu
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. Université du Maine, Le Mans France.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Centre for ECO2 Vehicle Design.
    Dazel, Olivier
    Université du Maine, Le Mans France.
    Simplification of the transfer matrix model for acoustic screens2018Conference paper (Refereed)
  • Mölleryd, Bengt A
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Governance of innovation - deploying an architectural framework for innovation of technological systems for energy, security and defence2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Governance of innovation – deploying an architectural framework for innovation of technological systems for energy, security and defence

    Innovation has a great deal of attraction but is associated with serious uncertainties and downsides. It is potentially beneficial for growth, sector and industrial development and competitiveness. Innovation brings hope of solving societal challenges, such as climate change and environment protection, and could help secure a supply of energy. Furthermore, it improves resilience and strengthens security and defence.

    The downside of innovations of some magnitude concern severe transitions and disruptions. Digitisation, with associated net technologies, is an illustrative example of an innovation that creates new services, competitiveness and other benefits which is enormously positive and attractive, while simultaneously dismantles and destroys existing systems, firms and branches, and whole sectors and practices.

    The thesis deals with promoting innovations at large but specifically systemic, defined as a value-adding (to customers and users) set or convergence of new products/services from technological systems in processes which emerge by evolutionary association and integration of systems transforming businesses, industries and sectors (with disruptions as consequence). Innovations are distinguished by certain structural properties namely systemicitiness. The systemicitiness of innovations suggests a distinct architectural framework that determines the structure of innovations. The purpose of the proposal for an architectural framework for innovation is guidance to governance of innovation. Platform based ecosystems exemplifies an emulation of systemic innovation that aligns with the proposed framework. The framework is distilled from cases, events, patterns, landscapes and models of innovation in the literature, connected with examination of systemicitiness and governance approaches to innovation and innovation processes. The architectural framework is conjected as compatible and complementary to common policies and instruments for innovation and innovation processes as holistic systems engineering, standards and protocols (e.g. ISO/IEC 15288:2015, ISO/IEC 42010:2011, NISP).

  • Manzari, Luca
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Mao, Huina
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Centre for ECO2 Vehicle Design.
    Cuenca, Jacques
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. Siemens Industry Software, Leuven Belgium.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Experimental-numerical methods for inverse characterization of the anisotropic-anelastic properties of porous materials, based on dynamic Digital Image Correlation2018Conference paper (Refereed)
    Abstract [en]

    One of the major challenges in accurately modeling poroelastic materials is the choice of the parametersrequired for their modeling, immediately followed by the practical difficulty in obtaining them. The direc-tional dependencies of the physical properties further complicate the task of designing experimental setupscapable of providing the macroscopic properties. In the work presented here, the focus has been set on theacquisition of high quality displacement data by means of two high-speed cameras and 3D Digital ImageCorrelation. The obtained displacement field, is fed into a general inverse formulation which is guided by anoptimization tool that minimizes the difference between the predicted and the measured data. As a minimumis found, the corresponding parameters are interpreted as material properties for a certain physical model.The solutions for each iteration are calculated with numerical prediction tools, in the cases discussed herethe finite element method, where it must be ascertained that the numerical errors are kept to a minimal level

  • Soukka, Erik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Chassis Design of a Control Pod for a Kite Power System2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This is the report of a master thesis in light weight design of a component in a system that harnesses wind power with a kite. The thesis is a degree project in Naval Architecture at KTH with the course code SD271X. The design work is mostly of a structural nature, but systems engineering, and conceptual design is also a major part of thestudy. The first part introduces the problem where the client, SkySails Power GmbH, is looking to design a new control pod for a system that carries 3 times the load as a previous design. The thesis is limited to the design of the load bearing chassis of the pod, but because at the time the other sub systems or components have not yetbeen designed, the study includes concept design of the entire pod system. The flight pattern and load cases of the kite are studied to get the right understanding of the forces that affect the system. The goal is to design achassis that is as affordable, light weight, and as strong as needed for the task.The requirements of the design problem are decided by the master student and the client together after a prestudy was made but they had minor changes further along the design process. It is a real life, organic iterative design process that has a goal from the start to use the opportunity of an outsider to reconsider the design of akey component of the client’s product.The result is a chassis design that is cheaper to produce and weighs less than if the old chassis would be linearly scaled up with the loads. This design has the same concept as the last but with a couple of modifications concerning some attachments to the rest of the system. The requirement of maintaining all previous functionsis achieved. A significant part of the thesis was to determine the boundaries between the areas of where FEM modelling is applicable and where hand calculations estimations are necessary. The results from this work will be used to build a prototype of the chassis, test it in a tensile testing machine, and finally integrate it into theentire system and flown.

  • Szadaj, Antek
    KTH, School of Engineering Sciences (SCI), Physics.
    Performance studies of Low-Gain Avalanche Diodes for the ATLAS High-Granularity Timing Detector2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • ESBJÖRNSSON, PER
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    SARRI, MARIA IOANNA
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Assessing motives for Corporate Entrepreneurship: Case study on established Nordic companies2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Due to constant disruption, companies need to embed innovation into their everyday activities in order to cope with competition and be successful. Corporate Entrepreneurship is playing an important role in fostering innovation and is needed to avoid disruption. However, companies have also different motives when handling CE as well as various ways of implementing it in the organization. This study investigated the motives of CE among large companies and the various implementation efforts. Therefore, the research question is: Which are the motives for CE? and the sub-question is: How does that lead to variation in CE implementation? The focus of the study was large companies which headquarter in Nordic countries and belong in different industries. Therefore, nine semi-structured interviews were performed and after, the data from the interviews were analyzed with thematic analysis. The results showed that the companies have different reasonings about their CE efforts and the CE implementation varied depending on the companies’ motives. However, these factors may not affect directly the organizational maturity. Therefore, companies can have their motives and support their CE efforts in different ways without influence negatively the maturity of the organization.

  • Public defence: 2019-01-25 10:30 H1, Stockholm
    Niazi Ardekani, Mehdi
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Numerical study of transport phenomena in particle suspensions2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Suspensions of solid particles in a viscous liquid are of scientific and technological interest in a wide range of applications. Sediment transport in estuaries, blood flow in the human body, pyroclastic flows from volcanos and pulp fibers in papermaking are among the examples. Often, these particulate flows also include heat transfer among the two phases or the fluid might exhibit a viscoelastic behavior. Predicting these flows and the heat transfer within requires a vast knowledge of how particles are distributed across the domain, how particles affect the flow field and finally how they affect the global behavior of the suspension. The aim of this work is therefore to improve the physical understanding of these flows, including the effect of physical and mechanical properties of the particles and the domain that bounds them.To this purpose, particle-resolved direct numerical simulations (PR-DNS) of spherical/non-spherical particles in different flow regimes and geometries are performed, using an efficient/accurate numerical tool that is developed within this work. The code is based on the Immersed Boundary Method (IBM) for the fluid-solid interactions with lubrication, friction and collision models for the close range particle-particle (particle-wall) interactions, also able to resolve for heat transfer equation in both Newtonian and non-Newtonian fluids.

    Several conclusions are drawn from this study, revealing the importance of the particle's shape and inertia on the global behavior of a suspension, e.g. spheroidal particles tend to cluster while sedimenting. This phenomenon is observed here for both particles with high inertia, sedimenting in a quiescent fluid and inertialess particles (point-like tracer prolates) settling in homogeneous isotropic turbulence. The mechanisms for clustering is indeed different between these two situations, however, it is the shape of the particles that governs these mechanisms, as clustering is not observed for spherical particles. Another striking finding of this work is drag reduction in particulate turbulent channel flow with disk-like spheroidal particles. Again this drag reduction is absent for spherical particles, which instead increase the drag with respect to single-phase turbulence. In particular, we show that inertia at the particle scale induces a non-linear increase of the heat transfer as a function of the volume fraction, unlike the case at vanishing inertia where heat transfer increases linearly within the suspension.

  • Semeniuk, Bradley
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Centre for ECO2 Vehicle Design.
    Dazel, Olivier
    Microstructure based modelling of the thermal and viscous dissipation of a transversely isotropic porous fibrous insulation material.2018Conference paper (Refereed)
  • Public defence: 2019-01-25 13:00 Kollegiesalen, Stockholm
    Gürdür, Didem
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Data and Visual Analytics for Cyber-physical Systems: Current Situation and Strategies for Action2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Today, cyber-physical systems (CPS) exist everywhere in different sizes, with different functionalities and capabilities. CPS often support critical missions that have significant economic and societal importance. They require software systems, communications technologies, sensors/actuators, embedded technologies, and physical systems to work together seamlessly, and they are seen as a driving force behind digital transformation. This dissertation describes the research work carried out to investigate applicability of data and visual analytics for CPS to overcome three main challenges: interoperability, complexity, and sustainability.

    To this end, several case studies are used to effectively implement and test different data and visual analytics solutions to aid stakeholders when they make decisions on interoperability, complexity, and sustainability for CPS. These studies raised questions about issues found to be of importance for the success of data and visual analytics approaches, including accessibility, availability, quality, volume, and variety of data—issues. Moreover, additional studies are used to show the benefits of blending different approaches, such as systems thinking and design thinking, and the current data analytics readiness of the Swedish industry is assessed through a questionnaire completed by more than a hundred respondents. 

    The data and visual analytics are positioned between digitalization and machine intelligence as a research focus. Data and visual analytics is the next step after digitalizing the information by adding analytical capabilities to the data. It is also an important phase before developing machine intelligence applications. Earlier studies clearly show that only a fraction of companies have machine intelligence applications across the enterprise. One important reason behind this is the lack of strong digital capabilities that big data and advanced data analytics technologies could bring. The findings of the work carried out as part of this thesis show the importance of this middle phase—data and visual analytics—for the success of not only the CPS but also these two concepts—digitalization and machine intelligence.

    This thesis concludes by highlighting that currentdata and visual analytics approaches in CPS are closely dependent onthe availability, accessibility, quality, volume, and variety of the data. Notably, the huge amount of industrial data that exists in CPS manufacturers data repositories does not always mean that this data is useful, especially for analytical purposes. To this end, firstly, the CPS industry should concentrate its efforts to collect useful data that will benefit the industry by providing analytical insight intothe environments where CPS is produced and operated. Secondly, the industry should make necessary organizational changes such as considering to employ data scientists, analysts, and business intelligence developers and make data accessible tothese people for further usage. Thirdly, the data management procedures and data analytics roadmaps of companies should be created and shared with other employees, and necessary mechanisms needto be considered to improve and guarantee the quality of the data. Lastly, the variety of data needs to be addressed by the industry. 

    Data and visual analytics provides an opportunity to extract patterns; to evaluate the interoperability, complexity, and sustainability; to create an overview of the current challenge by providing different viewpoints adapted to different stakeholders, focusing on key concerns for the respective stakeholder; to optimize performance, automation, and cooperation of distributed CPS, development environment, and teams; and overall, to improve any of the challenges that are mentioned above by, basically, providing a better understanding.

    To this end, I suggest that the industry discuss the next step after digitalization and address the challenges related to the availability, accessibility, quality, volume, and variety of data by considering user-centric approaches and organizational needs of the future development and manufacturing environments. The CPS industry should plan and act on these challenges as part of its data analytics strategies to expedite the machine intelligence applications of the future.

  • Public defence: 2019-02-01 10:00 Kollegiesalen, Stockholm
    Choutri, Salah Eddine
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Topics in Mean-Field Control and Games for Pure Jump Processes2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is the collection of four papers addressing topics in stochastic optimal control, zero-sum games, backward stochastic differential equations, Pontryagin stochastic maximum principle and relaxed stochastic optimal control.

    In the first two papers, we establish existence of Markov chains of mean-field type, with countable state space and unbounded jump intensities. We further show existence of nearly-optimal controls and, using a Markov chain backward SDE approach, we derive conditions for existence of an optimal control and a saddle-point for a zero-sum differential game associated with risk-neutral and risk-sensitive payoff functionals of mean-field type, under dynamics driven by Markov chains of mean-field type. Our formulation of the control problems is of weak-type, where the dynamics are given in terms of a family of probability measures, under which the coordinate process is a pure jump process with controlled jump intensities.

    In the third paper, we characterize the optimal controls obtained in the first pa-per by deriving sufficient and necessary optimality conditions in terms of a stochastic maximum principle (SMP). Finally, within a completely different setup, in the fourth paper we establish existence of an optimal stochastic relaxed control for stochastic differential equations driven by a G-Brownian motion.

  • Nigicser, David
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Valerio, Turri
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Arat, Mustafa Ali
    The Goodyear Rubber & Tire Company.
    Lima Simões da Silva, Eduardo
    DTU Space.
    Predictive Vehicle Motion Control for Post-Crash Scenarios2018Conference paper (Refereed)
    Abstract [en]

    This paper presents an active safety system for passenger vehicles designed to mitigate secondary collisions after an initial impact. Thecontrol objective is to minimize lateral deviation from the known original path while achieving a safe heading angle after the initialcollision. A hierarchical controller architecture is proposed: the higher layer is formulated as a linear time-varying model predictivecontroller that defines the virtual control moment input; the lower layer deploys a rule-based controller that realizes the requestedmoment. The designed control system is tested and validated on a high-fidelity vehicle dynamics simulator.

  • Lindberg, Julia
    et al.
    KTH, School of Industrial Engineering and Management (ITM). 1990.
    Hagman, Sarah
    KTH, School of Industrial Engineering and Management (ITM).
    CBA of environmental projects within hydropower2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hydropower is a fundamental pillar in the Swedish energy system and accounts for a large part of the Swedish electricity production. The regulation power is also essential for balancing the grid load.  Fortum is one of the leading energy companies within hydropower and Klarälven is a river with high importance, where Fortum owns and operates nine powerplants. These power plants constitute a barrier for the wild salmonids in Klarälven, which need to migrate upstream to reach their spawning area. Since the 1930s, the spawning salmonids have been trapped and transported upstream by lorry. After the spawning period, the smolts and kelts, i.e. the juvenile and spawned salmonids, have to migrate downstream. Due to the lack of fishways, they are forced to pass the eight remaining power plants. This, together with predation, entails a high mortality rate. Two independently performed studies indicates on survival rates of 16 % and 30 %. To stabilize the wild salmonid population, the downstream survival must increase, and a proposed solution is to implement a downstream trap-and-transport solution. This trap implementation could be a step towards the environmental adaptation of hydropower and a part of the action plan proposed in June 2016, during the Agreement on Swedish energy policy. To find the most cost-beneficial environmental measure, a socio-economic assessment method can be used. A Cost-Benefit Analysis (CBA) is a commonly used socio-economic method, which evaluates the benefits and costs during the entire project lifetime. Energiforsk has, within the project FRAM-KLIV, developed a CBA tool that aims to simplify the socio-economic evaluation. The purpose of this thesis was to investigate whether the CBA tool can be used in future permit processes to prioritize between different project proposals to find the most beneficial environmental improvements. In order to evaluate the tool, it was to be applied on the trap-and-transport project in Edsforsen to evaluate the possibility of a socio-economic profitability. Also, the concepts and theory behind CBA was to be analysed and the suitability of translating environmental consequences into monetary values was to be evaluated. In the analysis of Edsforsen, 13 scenarios were developed. The first scenario served as a basis for the other scenarios, which were created as a sensitivity analysis. The result of the CBA showed a large socio-economic benefit and the most important parameter was identified as people’s willingness to pay for an increase of the wild salmonid stock in Klarälven. In the CBA, this parameter had a high uncertainty, as it was based on a survey performed for another project in another part of Sweden. It was found that in order for the socio-economic result to be positive, all households in Sweden must be willing to pay at least 35 SEK. As a complement to the CBA result, an evaluation regarding the marginal cost per fish was performed and an interval of 50-580 SEK per smolt was obtained. However, the calculations were based on several uncertainties and the interval should therefore be interpreted as a guideline rather than a precise result. It was concluded that in situations when a socio-economic analysis is required, and when it is possible to express consequences in monetary values, the method of CBA is appropriate. It is also a suitable methodology for evaluations of large projects, as it provides a comprehensible overview of the costs and the benefits. Despite the criticism directed towards CBA regarding uncertainties and its anthropogenic perspective, it could be concluded that using CBA as a socio-economic assessment method provides a perspicuous and quantitative result. Thus, the usage of CBA in prioritization processes of different environmental measures can be highly useful. Energiforsk’s CBA tool provides a framework with guidelines that can be highly useful and accelerate the analysis process. However, the performance of the tool version used in this thesis was not fully satisfactory due to a few malfunctions. The tool is still under development and it is likely that these errors will be adjusted in future versions. If the malfunctions in the tool would be adjusted, it could become useful for authorities, companies and other actors that wants to evaluate hydropower related environmental measures or when prioritizing between different project proposals to find the most beneficial environmental improvements in future permit processes.

  • Public defence: 2019-01-21 10:00 Q2, Stockholm
    Čičić, Mladen
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Control of vehicle platoons and traffic dynamics: catch-up coordination and congestion dissipation2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Traffic congestion is a constantly growing problem, with a wide array ofnegative effects on the society, from wasted time and productivity to elevated air pollution and increased number of accidents. Classical traffic control methods have long been successfully employed to alleviate congestion, improving the traffic situation of many cities and highways. However, traffic control is not universally employed, because of the necessity of installing additional equipment and instating new legislation. 

    The introduction of connected, autonomous vehicles offers new opportunities for sensing and controlling the traffic. The data that most of the vehicles nowadays provide are already widely used to measure the traffic conditions. It is natural to consider how vehicles could also be used as actuators, driving them in a specific way so that they affect the traffic positively. However, many of the currently considered strategies for congestion reduction using autonomous vehicles rely on having a high penetration rate, which is not likely to be the case in the near future. This raises the question: How can we influence the overall traffic by using only a small portion of vehicles that we have direct control over? There are two problems in particular that this thesis considers, congestion wave dissipation and avoidance, and platoon catch-up coordination.

    First, we study how to dissipate congestion waves by use of a directly controlled vehicle acting as a moving bottleneck. Traffic data can help predict disturbances and constraints that the vehicle will face, and the individual vehicles can be actuated to improve the overall traffic situation. We extend the classical cell transmission model to include the influence of a moving bottleneck, and then use this model to devise a control strategy for an actuator vehicle. By employing such control, we are able to homogenize the traffic without significantly reducing throughput. Under realistic conditions, it is shown that the average total variation of traffic density can be reduced over 5%, while the total travel time increases only 1%.

    Second, we study how to predict and control vehicles catching up in order to form a platoon, while driving in highway traffic. The influences of road grade and background traffic are examined and vehicles attempting to form a platoon are modelled as moving bottlenecks. Using this model, we are able to predict how much the vehicles might be delayed because of congestion and adjust the plan accordingly, calculating the optimal platoon catch-up speeds for the vehicles by minimizing their energy consumption. This leads to a reduction of energy cost of up to 0.5% compared to the case when we ignore the traffic conditions. More importantly, we are able to predict when attemptingto form a platoon will result in no energy savings, with approximately 80% accuracy.

  • Lööf, Hans
    KTH, School of Industrial Engineering and Management (ITM), Centres, Centre of Excellence for Science and Innovation Studies, CESIS.
    A new approach to estimation of the R&D-innovation-productivity relationship2017In: Economics of Innovation and New Technology, ISSN 1043-8599, E-ISSN 1476-8364, Vol. 26, no 1-2, p. 121-133Article in journal (Refereed)
    Abstract [en]

    We apply a generalized structural equation model approach to the estimation of the relationship between R&D, innovation and productivity that focuses on the potentially crucial heterogeneity across sectors. The model accounts for selectivity and handles the endogeneity of this relationship in a recursive framework which allows for feedback effects from productivity to future R&D investment. Our approach enables the estimation of the different equations as one system, allowing the coefficients to differ across sectors, and also permits us to take cross-equation correlation of the errors into account. Employing a panel of Swedish manufacturing and service firms observed in three consecutive Community Innovation Surveys in the period 2008-2012, our full-information maximum likelihood estimates show that many key channels of influence among the model's components vary meaningfully in their statistical significance and magnitude across six different sectors based on the OECD classification on technological and knowledge intensity. These results cast doubt on earlier research which does not allow for sectoral heterogeneity.

  • Zhu, Biwen
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Visual Tracking with Deep Learning: Automatic tracking of farm animals2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Automatic tracking and video of surveillance on a farm could help to support farm management. In this project, an automated detection system is used to detect sows in surveillance videos. This system is based upon deep learning and computer vision methods. In order to minimize disk storage and to meet the network requirements necessary to achieve the real-performance, tracking in compressed video streams is essential.

    The proposed system uses a Discriminative Correlation Filter (DCF) as a classifier to detect targets. The tracking model is updated by training the classifier with online learning methods. Compression technology encodes the video data, thus reducing both the bit rates at which video signals are transmitted and helping the video transmission better adapt to the limited network bandwidth. However, compression may reduce the image quality of the videos the precision of our tracking may decrease. Hence, we conducted a performance evaluation of existing visual tracking algorithms on video sequences with quality degradation due to various compression parameters (encoders, target bitrate, rate control model, and Group of Pictures (GOP) size). The ultimate goal of video compression is to realize a tracking system with equal performance, but requiring fewer network resources.

    The proposed tracking algorithm successfully tracks each sow in consecutive frames in most cases. The performance of our tracker was benchmarked against two state-of-art tracking algorithms: Siamese Fully-Convolutional (FC) and Efficient Convolution Operators (ECO). The performance evaluation result shows our proposed tracker has similar performance to both Siamese FC and ECO.

    In comparison with the original tracker, the proposed tracker achieved similar tracking performance, while requiring much less storage and generating a lower bitrate when the video was compressed with appropriate parameters. However, the system is far slower than needed for real-time tracking due to high computational complexity; therefore, more optimal methods to update the tracking model will be needed to achieve real-time tracking.

  • Pham, Cong-Toan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Månsson, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Technical assessment of energy storage systems for power system applications via suitability index approach (Part IV)Manuscript (preprint) (Other academic)
    Abstract [en]

    Energy storage systems provide several benets and services in optimizing the power grid's reliability, effciency and safety. However, the feasibility of energy storage systems varies dependent on the requirements of the applications. Technical limitations in design and type of the storage technology prevents a single storage type to perform equally well in all situations. Hence,it is essential to compare and measure the energy storages' usefulness anddetermine their optimal use. To address this issue this study introduces an indexing approach to evaluate the suitability of energy storages for power system applications. Four different energy storages (double-layer capacitor, flywheel, lead-acid battery, lithium-ion battery) are tested for four typical energy storage applications (frequency regulation, voltage support, capacity firming and energy time-shift). The suitability index allows a simple and intuitive way to compare and rank the suitability of energy storages.

  • Björlin Svozil, Louise
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Beslutsgrund: en studie av utbildningsval bland kvinnliga elever på gymnasieskolans Naturvetenskaps- och Teknikprogram2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Education in engineering sciences in Sweden have for the past hundred years gone from solely recruiting men to a 36 percentage of female students. Even though the number of women is progressing in some fields, other fields still have as low proportion as 16 percent. The largest base for recruiting engineering students is the Swedish gymnasium programs in Sciences (NV) and in Technology (TE). The research method grounded theory (GT) was used when female students in NV and TE were interviewed to investigate the main concern of these students making choices about present and future studies. A broad spectrum of reasons, summarized in the core category Reasons for Decision (Beslutsgrund), showed that the students took into consideration the labour market, eligibility to university, the ranking of an education, expectations for social belonging, self-efficacy, grades, avoidance of a school subject, if the education led to the desired career, work load and work load in relation to eligibility. The execution of GT showed that this method could be used within the frame of a master thesis and that there are challenges and advantages in the combination.

  • Maroufi, Payam
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Improving Traction Efficiency in Off-Road Vehicles - A Sliding Mode Approach2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report evaluates the option of using an equal slip controller, an effective rolling radius and rolling resistance force observer in a 4WD wheel loader. The vehicle studied is an under development- vehicle designed by Volvo CE. A wheel loader is an over actuated, articulated vehicle that is mainly used with low velocities in construction operations. The efficiency subject has been studied earlier by many manufacturers in order to analyze the environmental and economical losses and profits. This has provided research opportunities of optimizing efficiency of different kinds.

    Since the tire is the only part of a vehicle that is in contact with the ground, the characteristic of the tire effects the dynamics. The analysis shows that the efficiency of a tire is directly connected to the slip ratio which in turn is a component of the overall efficiency ratio. Studies show that the slip ratio should be controlled in such a way that the highest value of efficiency rate is obtained. This optimal value is dependent on all four wheel’s slip conditions. Therefore a strategy should be formulated in order to apply changes to all wheels and not only one. Further analysis shows that the maximum efficiency in a 4WD wheel loader is obtained when the vehicle runs in such a way that the slip ratio is equal for all wheels.

    I order to maintain same amount of slip for all wheels a control strategy is required. In the control strategy the current amount of slip of each wheel is determined. Further, the average value of slip ratio is calculated. Finally the equal amount of slip is achieved using corresponding optimal torque inputs for each individual wheel. Thus a stable, robust controller is required. The controller used to achieve this goal is a sliding mode controller that is popular among control engineers for its stability, robustness against uncertainties, speed and easy implementation.

    For an accurate control, states of the rolling resistance and the effective rolling radius need to be determined. The pressure acting on the tire will cause deformation on the tire itself. This leads to a dynamic radius of the tire. This deformation is highly dependent on vertical stress and the structure of tire. Further more velocity, inflation pressure, vertical load etc. also have effect on rolling resistance. Rolling resistance has a great impact on the fuel consumption of the vehicle and the driving characteristics. These estimated variations of effective radius and rolling resistance build a feedback system to the controller which in turn derives the system to the desired slip ratio. As it turns out, the slip efficiency is increased using an equal slip controller. However, it is highly dependent on the ratio of thrust between front and rear wheels.

  • Beckman, Claes
    Implications of Dual Band Functionality on Base Station Antenna Development1997In: Dual Band/Multi Band '97 / [ed] Center for EuroTelecomms, London, 1997Conference paper (Other academic)
    Abstract [en]

    The recent growth in cellular communications has rapidly created a need for more radio channels. In order to make better use of the available frequency bands new access techniques such as TDMA (Time Division Multiple Access), FDMA (Frequency DMA) and CDMA (Code DMA) have been introduced. Still, the need for new channels is strong and new frequency bands have therefore been allocated for wireless communication systems.

    These new communication systems, e.g. the European Personal Communication Network (PCN: 1710-1880MHz) and the North American Personal Communication System (PCS: 1850-1990MHz), use frequencies about twice as high as their predecessors (e.g. AMPS: 824-894MHz and GSM: 880-960MHz). However, at a time when our downtown areas already are littered with antennas, operators are not keen to install more.

    One solution could be to replace existing GSM or AMPS antennas with dual band GSM/PCN or AMPS/PCS. This would reduce the windload of the towers, the number of feeder cables and the whole  cost of tower installations. If the dual band antennas were to be dual polarized also, the four antennas today being needed for receiving the PCN and GSM bands in a sector, could actually be replaced by one only.

  • Fredén, Gustaf
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Persson, Erik
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Maskininlärning som verktyg för att förbättra planering i produktion2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Production planning for products with high seasonality can be difficult, as demand can increase rapidly, and it can be difficult to predict exactly when this increase will happen. Propane gas is such a product, where demand is significantly higher during summer than during winter. This study is conducted for AGA, the market leader for propane in the Nordic region, with the purpose to explore if machine learning can be used to improve their production planning. Different regression models where used to execute the study, with the result that none of them could be implemented with high enough proficiency to be used to predict future demand of propane and aid the production planning. The reason that the implementations failed was that too few input parameters where used for the machine learning models, and that those parameters that were used had too low correlation.​

  • Public defence: 2019-01-18 14:00 F3, Stockholm
    Tegling, Emma
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Fundamental Limitations of Distributed Feedback Control in Large-Scale Networks2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Networked systems accomplish global behaviors through local feedback interactions. The purpose of a distributed control design is to select interaction rules and control protocols that achieve desired global control objectives. In this thesis, we address the question of fundamental limitations to such control designs, in terms of the global performance that is achievable in large-scale networks. 

    We consider networked dynamical systems with single- and double- integrator dynamics controlled with linear consensus-like protocols. Such systems can be used to model, for example, vehicular formation dynamics and synchronization in electric power networks. We assume that the systems are subject to distributed disturbances and study performance in terms of H2 norm metrics that capture the notion of network coherence. In the context of power networks, we also show how such metrics can be used to quantify resistive losses caused by non-equilibrium, or transient, power flows due to a lack of synchrony. 

    Distributed static feedback control based on localized, relative state measurements is subject to known limitations that, for example, cause coherence metrics to scale unfavorably with network size in lattices of low spatial dimensions. This causes an inevitable lack of rigidity in one-dimensional formations, such as strings of vehicles. We show here that the same limitations in general apply also to dynamic feedback controllers that are locally of first order. The proof relies partly on a fundamental limitation of localized relative feedback in networks of integrators of order three or higher, which we show to cause instability if the network grows beyond a certain finite size. 

    This result holds unless the controller can access measurements of its local state with respect to an absolute reference frame, in which case dynamic feedback in the form of distributed derivative or integral control can fundamentally improve performance. This case applies, for example, to frequency control in power networks. However, if the absolute state measurements are subject to noise, the advantage of the distributed integral controller in terms of its performance scaling is lost. We show that scalable integral control of networks in principle requires centralization or all-to-all communication. 

    For electric power networks, we show that performance in terms of transient power losses scales with the number of generator nodes in a network. However, in sharp contrast to the previous results, an increased connectivity does not in general improve performance. We discuss possible implications of these results in terms of the design of future power grids with increasingly distributed electricity generation. 

  • Public defence: 2019-02-01 14:00 rum A124 , KTH Arkitekturskolan,, Stockholm
    Hällgren, Nina
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Designing with Urban Sound: Exploring methods for qualitative sound analysis of the built environment2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The licentiate thesis Designing with Urban Sound explores the constitution and qualitative characteristics of urban sonic space from a design-oriented and practice-based perspective. The act of lifting forth and illuminating the interaction between architecture, the creation of sound and a sonic experience aims to examine and develop useful tools and methods for the representation, communication and analysis of the exterior sonic environment in complex architectural spaces. The objective is to generate theoretical and practical knowledge within the field of urban sound planning and design by showing examples of different and complementary ways of communicating and analyzing sound than those which are commonly recognized. 

  • Andricciola, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Development of an algorithm for the automatic adjustment of the heating curve of a heat pump heating system2018Independent thesis Advanced level (degree of Master (Two Years)), 5 HE creditsStudent thesis
    Abstract [en]

    This work deals with the problem of choosing the correct heating curve for a certain building package (envelope plus distribution system). This topic is particularly relevant in countries like Sweden where heating curve is the most common way to control heat pumps. The analysis, involving four building models with respective distribution systems (two have floor heating and two radiators) and a variable speed GSHP, shows how, for a fixed location, the proper heating curve changes considering different building envelopes and different emitters. It is highlighted, therefore, how the adoption of a generic heating curve for all the buildings can cause discomfort and energy inefficiency. An algorithm to adjust the curve is then presented, and the results are compared with the reference case. The algorithm manages to improve comfort considerably and, for the A-class building, also SPF increases a lot (12.5%). The whole study was performed by means of TRNSYS® neglecting the DHW demand.

  • Li, Anqi
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Possibilities for removal of micropollutants in small-scale wastewater treatment - methods and multi-criteria analysis2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The quality of worlds’ water resources is facing new challenges, for instance detectable concentration of various trace contaminants under the term micropollutants is discharging into water bodies from both municipal wastewater treatment plants and from on-site wastewater facilities. A project called RedMic aim at identifying and quantifying emissions of micropollutants from on-site wastewater treatments as a basis for providing innovative treatment technologies to reduce potential risks for groundwater and surface water contamination. This thesis work deals with two of the work packages in the RedMic project: a column experiment to test the capability of 10 adsorbents to remove micropollutants and a multi-criteria analysis is conducted to evaluate if a filter composed of granulated activated carbon (GAC) or ozonation can be used for on-site wastewater treatment facilities.

    Based on the removal efficiency of dissolved organic carbon (DOC) of selected adsorbents, two types of activated carbon reduced up to 90% DOC concentration in the effluents. Moreover, six other adsorbents also showed good removal efficiency with around 60% in the second sampling. However, the data used in this thesis was only from the initial part of the experiment that continued and the final results will be published elsewhere. Two system solutions were evaluated with multi-criteria analysis: sandbed filter with either GAC filtration (1) or with ozonation (2) System solution 1 was found to have advantage compared to system 2.

  • Public defence: 2019-01-22 10:00 U61, Stockholm
    Bekele, Abiy
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Application of Automated Non-contact Resonance Testing for Low Temperature Behavior of Asphalt Concrete2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Impact resonance testing is a well-documented non-destructive testing method and its applications on asphalt concrete have also been implemented successfully. The test is carried out manually by inducing an impact in order to excite the test specimen and taking measurements of the vibrational response. In an effort to improve the manual procedure of impact resonance testing, an automated non-contact methodology is developed and its applicability with regards to low temperature behaviors of asphalt concrete is investigated. Results from this work show that repeatable fundamental resonance frequency measurements can be performed on a disc shaped specimen in an automated manner without the need to open the thermal chamber. The measurements obtained from the new method have been verified by taking similar resonance frequency measurements using an instrumented impact hammer. It has also been shown in this work that the proposed method is suitable to investigate the lone effects of cyclic thermal conditioning on asphalt concrete without any other possible biasing effects associated with contact in the conventional testing. A hysteretic behavior of stiffness modulus is obtained on three different asphalt concrete specimens subjected to repeated low temperature cyclic conditioning. Reduced modulus values at each temperature are obtained in all the tested specimens after a low temperature stepwise conditioning at temperatures from 0oC to -40 oC. This observed behavior shows that the dynamic modulus of the tested specimens is affected by low temperature conditioning. The norm of the complex modulus decreases and the phase angle or damping ratio increases after low temperature conditioning. Hence, valuable and practical low temperature characteristics of different asphalt concrete mixtures can possibly be obtained by using the proposed methodology.

  • Ekwall, Axel
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Holm, Linnea
    KTH, School of Electrical Engineering and Computer Science (EECS).
    The relation between human-to-human interaction and human-to-tablet interaction in a neurocognitive test2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Our lives become longer with new advancements in medicine and technology. As a result, cognition and memory impairments will become a growing concern[23]. To be able to treat cognitive decline, dementia and related diseases, the need for early detection of memory deficiencies increases. This study aimed to validate the use of a new digital interaction version of a common memory test, the Rey Auditory Verbal Learning Test (RAVLT), compared with norm from the traditional human-to-human interaction version of the same test. This was performed through userstudies with both test versions in a counterbalanced order. The results consisted of quantitative results from the tests together with qualitative data from interviews with the participants in connection to each test occasion. The results showed a slight difference in some aspects of the quantitative test results, but at the same time, no significant difference for most of the measured results. Further, the interviews demonstrated that the differences in interaction and experience between the versions of the tests could be the reason for some of the differences in the quantitative result. The conclusion from this study was that there are many difficult problems to solve for speech interfaces in neurocognitive tests like the RAVLT. In line with previous research [22], the results highlight the importance of a natural speech interaction that conforms with the basic principles of human conversation, to create a stress-free experience and test results that can be reliable and comparable.

  • Gedik, Berk
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Evaluation of Text-Independent and Closed-Set Speaker Identification Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Speaker recognition is the task of recognizing a speaker of a given speech record and it has wide application areas. In this thesis, various machine learning models such as Gaussian Mixture Model (GMM), k-Nearest Neighbor(k-NN) Model and Support Vector Machines (SVM) and feature extraction methods such as Mel-Frequency Cepstral Coefficients (MFCC) and Linear Predictive Cepstral Coefficients (LPCC) are investigated for the speaker recognition task. Combinations of those models and feature extraction methods are evaluated on many datasets varying on the number of speakers and training data size. This way, the performance of methods in different settings are analyzed. As results, it is found that GMM and KNN methods are providing good accuracies and LPCC method performs better than MFCC. Also, the effect of audio recording duration, training data duration and number of speakers on the prediction accuracy is analyzed. 

  • Lundberg, Didrik
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Provably Sound and Secure Automatic Proving and Generation of Verification Conditions2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Formal verification of programs can be done with the aid of an interactive theorem prover. The program to be verified is represented in an intermediate language representation inside the interactive theorem prover, after which statements and their proofs can be constructed. This is a process that can be automated to a high degree. This thesis presents a proof procedure to efficiently generate a theorem stating the weakest precondition for a program to terminate successfully in a state upon which a certain postcondition is placed. Specifically, the Poly/ML implementation of the SML metalanguage is used to generate a theorem in the HOL4 interactive theorem prover regarding the properties of a program written in BIR, an abstract intermediate representation of machine code used in the PROSPER project.

  • Frisell, Marcus
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Information visualization of microservice architecture relations and system monitoring: A case study on the microservices of a digital rights management company - an observability perspective2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    90% of the data that exists today has been created over the last two years only. Part of the data space is created and collected by machines, sending logs of internal measurements to be analyzed and used to evaluate service incidents. However, efficiently comprehending datasets requires more than just access to data, as Richard Hamming puts it; "The purpose of computing is insight, not numbers." A tool to simplify apprehension of complex datasets is information visualization, which works by transforming layers of information into a visual medium, enabling the human perception to quickly extract valuable information and recognise patterns.

    This was an experimental design-oriented research study, set out to explore if an information visualization of microservice architecture relations combined with system health data could help developers at a Swedish digital rights management company (DRMC) to find root cause incidents, increase observability and decision support, i.e. simplifying the incident handling process.

    To explore this, a prototype was developed and user tests consisting of a set of tasks as well as a semi-structured interview was executed by ten developers at DRMC. The results concluded that the proposed solution provided a welcomed overview of service health and dependencies but that it lacked the ability to effectively focus on certain services, essentially making it difficult to find root causes.

    Visualizations like this seems to be best suited for overview-, rather than focused, comprehension. Further research could be conducted on how to efficiently render large complex datasets while maintaining focus and how to account for external factors.

  • Rosell, Felicia
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Tracking a ball during bounce and roll using recurrent neural networks2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In many types of sports, on-screen graphics such as an reconstructed ball trajectory, can be displayed for spectators or players in order to increase understanding. One sub-problem of trajectory reconstruction is tracking of ball positions, which is a difficult problem due to the fast and often complex ball movement.

    Historically, physics based techniques have been used to track ball positions, but this thesis investigates using a recurrent neural network design, in the application of tracking bouncing golf balls. The network is trained and tested on synthetically created golf ball shots, created to imitate balls shot out from a golf driving range.

    It is found that the trained network succeeds in tracking golf balls during bounce and roll, with an error rate of under 11 %.

  • Vanacker, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Improvement of an advanced kinetic Monte Carlo algorithm through storing and recycling factorised transition matrices2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Kinetic Monte Carlo algorithm is a universal method to simulate the evolution of systems governed by a master equation. However, this approach is severely limited by the kinetic trapping of the simulated trajectories in low energy basins. To alleviate this issue, non-local transitions escaping the trapping basins are performed based on a factorisation of the transition matrix associated with the master equation.

    Whenever trapping becomes severe, the simulation repeatedly visits a limited number of basins and performs the same factorisations many times. In this report, we present two methods aiming at further improving the efficiency of the factorised Kinetic Monte Carlo algorithm.

    The first method consists of storing and recycling the transition matrix factorisations, while the second method constructs on-the-fly a graph connecting the factorised transition matrices. The efficiency of these methods is demonstrated on simulations of cluster migration in an iron-based alloy.

  • Heinig, Stefanie
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Jacobs, Keijo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Ilves, Kalle
    ABB Corp Res, Forskargrand 7, SE-72178 Vasteras, Sweden..
    Norrga, Staffan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Reduction of Switching Frequency for the Semi-Full-Bridge Submodule Using Alternative Bypass States2018In: 2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    As regards modular multilevel converter submodules, a different number of switches may be involved in the transitions between voltage levels depending on the submodule type and choice of switching states. In this paper, an investigation of the average switching frequency associated with different choices of bypass states is performed for the semi-full-bridge submodule. Theoretical considerations and simulation results show that the average switching frequency per device can be halved by using the proposed alternative bypass state. Moreover, the switching losses can be reduced by up to 60%. Finally, a comparative study with the full-bridge submodule has been conducted.

  • Mazzotti, Willem
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lazzarotto, Alberto
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Deep Boreholes for Ground-Source Heat Pump: Final report2018Report (Refereed)
    Abstract [en]

    This report presents the obtained results and performed tasks during the project Deep Boreholes for Ground-Source Heat Pumps, within the framework of the research program Effsys Expand.

    A price model for the investment of GSHP system with deep Borehole Heat Exchangers (BHEs) is derived from a survey submitted to Swedish drillers. Notably, it is shown that the price increases with the borehole depth in a cubic fashion. Up to 300 m depth, the model shows a good match with a linear correlation having a slope of 275 SEK/m, a figure that is close to commonly used estimates for the total installation price of a single BHE. For larger depths, however, the installation price becomes non-linear and deviates from this linear tendency. Examples of total installation prices, including heat pumps and BHEs installation, are given.

    Measurements performed in three different installations with deep boreholes are reported. The first tests are performed in a 800 m deep borehole equipped with acoaxial collector. Five Distributed Thermal Response Tests (DTRTs) are performed inthis BHE of which four were heat-extraction DTRTs. It is shown that heat flux inversion happens along the depth of the boreholes, that is heat is extracted at the bottom of the borehole but lost at the top. The flow rate is shown to have a significant effect on the thermal shunt effect and the coaxial BHE is shown to have significantly lower pressure drops that more traditional BHE (e.g. U-pipes). The pressure drop vs. flow rate relation is experimentally characterized through a hydraulic step test. An effective borehole resistance of 0.21 m∙K/W was found. This value is relatively high and is explained as a consequence of limited flow rate and the large depth. More investigations as regards the measurement technique (DTS with fiber optic cables) are needed before performing further in-depth analysis.

    In another installation, four 510 m boreholes are measured to deviate about 30% from the vertical direction, highlighting the importance of drilling precision for deep boreholes, more particularly in urban environment. The GSHP system, using 50mmU-pipe BHEs is monitored over a year and it is found that pumping energy consumption in the boreholes could be as high as 22% of the total energy consumption of the system (compressors and circulation pumps). The relevance of pressure drops and control strategies for the circulation pumps in the borehole loop is emphasized. The temperature profile with depth confirms the existence of stored heat in the top part of the ground in urban environment.

    The results of two DTRTs performed in the same borehole (335 m) are reported, thelatter being first water-filled before being grouted. The obtained thermal conductivities differ from one case to another, possibly highlighting the effect of the filling material on the results. Several other explanations are proposed although none can be fully verified.

    The design and construction phases of a laboratory-scale borehole storage model are reported. The design phase mainly focused on deriving analytical scaling laws and finding a suitable size for such a model. Through the design analysis, an explanation to the discrepancy observed in the only previous attempt to validate long-term thermal behavior of boreholes is proposed.

    Investigations as regards the KTH heat pump system, optimum flow rates in GSHPsystems with deep BHEs and quantification of thermal influence between neighboringboreholes are discussed although the work could not be fully completed within thetimeframe of the project.

    The dissemination of knowledge through different activity is reported.

  • Bekele, Abiy
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Effect of Cyclic low temperature conditioning on Stiffness Modulus of Asphalt Concrete based on Non-contact Resonance testing methodManuscript (preprint) (Other academic)
    Abstract [en]

    The stiffness modulus behaviors of three different asphalt concrete specimens that are subjected to cyclic cooling and heating are monitored. In an attempt to identify the sole effect of temperature cycles and to avoid any other biasing effects such as thermal contamination that can possibly corrupt measurements, resonance frequency measurements of the specimens are taken using an automated non-contact resonance method. The resonance frequency measurements are based on the fundamental axially symmetric mode of vibration. A hysteretic effect is observed on the measured resonance frequencies of the specimens with an application of cyclic cooling and heating. Lower stiffness moduli are obtained during the heating phase of a complete cooling and heating cycle. The stiffness moduli are calculated from measured resonance frequencies of the specimens in order to show their relative reductions due to the hysteretic effect. This finding is particularly important since it enables us to observe and understand the effect of the thermal history of asphalt concrete with regards to the reversibility behavior of its stiffness modulus. The damping of the specimens is also calculated from the measured resonance frequencies at the temperatures within the applied cyclic cooling and heating. Their observed behavior is also discussed with respect to a presence of potential micro damage.

  • Bekele, Abiy
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Automated Non-contact Resonance Excitation Method for Low Temperature Behavior of Asphalt ConcreteManuscript (preprint) (Other academic)
    Abstract [en]

    This paper studies the applicability of an automated non-destructivetesting method to monitor the stiffness of asphalt concrete at lowtemperatures. A loudspeaker is used as a source of non-contact excitation ofthe axially symmetric fundamental resonance frequencies of a disc-shapedasphalt concrete specimen positioned inside an environmental chamber. Measuredresonance frequencies are used to calculate the dynamic moduli of the specimenat different temperatures. The repeatability of the method as well as theeffect of loudspeaker height above the sample are studied. Results show thatthe main advantage of the non-contact excitation method, compared to manuallyapplied impact hammer excitation, is that repeatable automated measurements canbe performed while the specimen is placed inside an environmental temperaturechamber. This methodology enables to study the effect of only low temperatureconditioning on the dynamic modulus of asphalt concrete without interferencefrom mechanical loading.

  • Niarchos, Georgios
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Electrodialytic Remediation of PFAS-Contaminated Soil2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a group of anthropogenic aliphatic compounds, widelyknown for their environmental persistence and toxicity to living beings. While they are ubiquitous in theenvironment, interest has been focused on contaminated soil, which can act as a primary recipient andsource of groundwater contamination. Electrokinetic technology is based on the movement of ionsunder the effect of an electric field. This could be a promising remediation solution, since PFASs areusually present in their anionic form. The contaminants can then be concentrated towards the anode,thus reducing a plume’s volume and possibly extracting the substances from soil. The preliminary aimof the present study was to evaluate the potential of using electrodialysis for the remediation of PFAScontaminatedsoil for the first time. Experiments were run with natural contaminated soil samples,originating from a fire-fighting training site at Arlanda Airport, and at Kallinge, Sweden, as well as inartificially spikedsoil. Electrodes were placed in electrolyte-filled chambers and separated by the soilwith ion-exchange membranes for pH-control. In total, five experiments were conducted. Two differentsetups were tested, a typical 3-compartment EKR cell and a 2-compartment setup, to allow for pHincrease and facilitate PFAS desorption. Two different current densities were tested; 0.19 mA cm-2 and0.38 mA cm-2. After twenty-one days, soil was cut in ten parts lengthwise and triplicate samples wereanalysed for PFAS concentrations, with HPLC-MS/MS. Sixteen out of the twenty-six screened PFASswere detected above MDL in the natural soil samples. The majority of the detected PFASs showed apositive trend of electromigration towards the anode, under both current densities, with only longerchainedcompounds (c>8) being immobile. This can be attributed to the stronger sorption potential oflong-chained PFAS molecules, as has been reported in previous sorption studies. Mass balancedistribution for a high current density (0.38 mA cm-2) experiment revealed that 73.2% of Σ26PFAS wasconcentrated towards the anode, with 59% at the soil closer to the anode, 5.7% at the anion exchangemembrane and 8.5% at the anolyte. It also showed higher mobility for short-chained molecules (c≤6),as they were the only compounds to be extracted from soil and be concentrated in the anolyte. Highercurrent densities were not directly correlated with higher electromigration rates, as to the lack of massbalance data for the low current density experiments. Regardless, electrodialysis could be a viable optionfor PFAS soil remediation and further research to encourage the understanding of the migrationmechanism, as well as combination with other treatment methods is encouraged.

  • von Bahr, Maximilian
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Gomez Bergström, Ida
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Investigation of the origin of salt in coastal aquifers and assessment of metals in the aquatic environment: River Drin and River Vjosa, Albania2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The preservation of freshwater aquifers is one important task of managing natural resources today. Intrusion of saltwater from the sea into the groundwater might occur in coastal-near areas and can affect the freshwater quality negatively. One such risk area is the Adriatic coast line of Albania, a country predominantly rich in freshwater resources due to the numerous rivers flowing from the mountains in the east towards the sea. The coastal areas are mainly used for agricultural activities were groundwater is an important resource for irrigation purposes. This study was therefore partly conducted in Albania where samples of groundwater and river waters were collected from the river deltas of Drin and Vjosa in order to investigate the origin of the salt and to assess the bioavailable metal concentrations of nickel and zinc. Both on-site tests and off-site tests, in laboratories, were conducted. In the laboratory, the samples were analysed for oxygen and deuterium isotope data. The results were used to assess the origin of the oxygen content as the method of investigating the origin of the salt uses the oxygen isotope as a tracer. Anion and cation concentrations were analysed as well as the concentrations of metals. These were used as input data to Visual Minteq, a model used to calculate the metal speciation of waters, and a Biotic Ligand Model used to calculate the bioavailable concentrations and the HC5 concentrations. The isotope analysis yielded results similar to previous studies conducted in the nearby area indicating that the salt does not have oceanic origin but meteorological. The bioavailable concentrations were in most sample sites lower than the calculated HC5 concentrations indicating that there is a sufficient buffering system present even though there are several mining activities upstream of the sample sites that could have affected the water quality.

    This study concludes that the origin of salt is of meteoric origin and not from seawater intrusion. The bioavailable concentrations do not pose a threat as the concentrations are under the HC5 concentrations for all sites but one.

    In order to deepen the understanding and knowledge of the water qualities in these areas, future studies should focus on a continuous measuring period lasting for example over the whole year minimizing any seasonal variations of the sampled data. Other methods such as geophysical measures could also contribute to a wider analysis of the groundwater condition.

  • Engholm, Albin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Kristoffersson, Ida
    VTI Statens väg- och transportforskningsinstitut.
    System-level impacts of self-driving vehicles: terminology, impact frameworks and existing literature syntheses2018Report (Other academic)
    Abstract [en]

    The intention with this report is to contribute toward the development of systemic and holistic studies of impacts of self-driving vehicles. The report is targeting system-level impacts of self-driving vehicles on the transportation system but also wider societal impacts on factors such as: land-use, public health, energy and emissions, etc. This report is complimentary to two papers that are focused on in-depth literature review of simulation studies  (Pernestål Brenden and Kristoffersson 2018) and future scenario studies of impacts of self-driving vehicles (Engholm, Kristoffersson, and Pernestål Brenden 2018).

    The first aim of the report is to summarize knowledge to enable future design of a high-level conceptual framework for impacts from self-driving vehicles from a systems perspective. The second aim is to summarize knowledge on impacts from self-driving vehicles in a selection of the available literature. The main contributions of the report are the following:

    • A terminology for different types of automated vehicles, connected vehicles and mobility concepts for automated vehicles is presented
    • Frameworks for classifying system-level impacts from SDVs in the existing literature are summarized and analyzed
    • Existing literature studies on system-level impacts from SDVs are synthesized and common themes and gaps in current research are analyzed

    The terminology proposed in this report distinguishes between different types of automated and connected vehicles and is primarily intended as a tool to enable stringent analysis in this report when analyzing literature that apply different terminologies. Two frameworks for classifying system-level impacts are identified and compared. The analysis of the frameworks covers their scope, specification of mechanisms generating system impacts and briefly reviews their applicability as a starting point for developing a systems model of impacts from self-driving vehicles. The review of existing literature syntheses shows that there is a large variation in availability on literature for different system impacts. Impacts on road safety, road capacity and vehicle ownership forms are well studied. Examples of less studied impacts are costs of ownership, public health, infrastructure, air pollution and accessibility. The review identifies several contractionary mechanisms and effects that can affect various system-level impacts. The results of the review highlight the need to approach impact assessments of self-driving vehicles from a systemic and holistic point of view.