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  • 124251.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle.
    Ödman, Torbjörn
    SAAB Electronic Defence Systems, SAAB AB.
    Bäckström, Mats
    SAAB Aeronautics, SAAB AB.
    Vallhagen, Bengt
    SAAB Aeronautics, SAAB AB.
    Shielding Effectiveness Study of Two Fabrics with Microwave Properties Before and After High Power Irradiation2015In: Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA)ICEAA '15 - 17th Edition, IEEE conference proceedings, 2015, p. 930-933Conference paper (Refereed)
    Abstract [en]

    Over the past decade several applications forfabrics with electromagnetic properties have emerged, most ofthem relating to garments, including jackets with built-inantennas and workwear with increased radar visibility. Besidethese have surfaced two protective applications, namely toprotect transports of confidential equipment from discoveryand identification; and to protect sensitive apparatus fromdamage by high power electromagnetic irradiation e.g. in fieldoperations. In this paper results are presented frommeasurement of shielding effectiveness before and after highpower radiation for two types of fabrics under considerationfor the latter applications. Shielding effectivenessmeasurements have been conducted between 1 and 18 GHzwhile the high power irradiation

  • 124252.
    Ärlemalm, Filip
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Harbour Porpoise Click Train Classification with LSTM Recurrent Neural Networks2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The harbour porpoise is a toothed whale whose presence is threatened in Scandinavia. Onestep towards preserving the species in critical areas is to study and observe the harbourporpoise population growth or decline in these areas. Today this is done by using underwateraudio recorders, so called hydrophones, and manual analyzing tools. This report describes amethod that modernizes the process of harbour porpoise detection with machine learning. Thedetection method is based on data collected by the hydrophone AQUAclick 100. The data isprocessed and classified automatically with a stacked long short-term memory recurrent neuralnetwork designed specifically for this purpose.

  • 124253.
    Ärlemo, Maria
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Feminisms in conflict: 'Feminist urban planning' in Husby, Sweden2018In: Architecture and feminisms: Ecologies, economies, technologies / [ed] Hélène Frichot, Catharina Gabrielsson, Helen Runting, New York: Routledge, 2018, p. 192-201Chapter in book (Other academic)
  • 124254.
    Ärnström, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Bergman, Johan
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Attracting the right employees: A study of successful employer branding2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Employer branding is an area of growing importance and attention. Though the concept of attracting and recruiting employees is by no means a new one, the idea of the employer brand implies a more conscious opinion of companies as employers by potential employees and as a result a more considered approach by companies themselves. 

    The purpose of this thesis is to analyze how the attract stage of employer branding in an anonymous company could be improved and formulate suggestions for improvement. The analysis is performed with three different focuses: formulating an employer branding strategy, organizing a structure to implement this strategy and communication of the desired image and brand values.

    Results show that the company is lacking in many areas and have potential for improvement in several key areas. The general analysis is that focus in employer branding is moving towards a more active dialogue with the target group where transparency and relations are emphasized. The company could improve their employer branding management by defining on a more specific target group, prioritize the opinion of this group over the general student population and use local brands more in the communication.

  • 124255. Åberg, A.
    et al.
    Höffken, J.
    Lidström, Susanna
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Looking for perspectives! EU energy policy in context2018In: Advancing Energy Policy: Lessons on the Integration of Social Sciences and Humanities, Springer International Publishing , 2018, p. 47-59Chapter in book (Other academic)
    Abstract [en]

    Transitioning to less carbon-intensive energy systems involves making difficult choices and priorities. This chapter imagines three individuals who are affected in different ways by EU energy policy. Their fictional stories illustrate that energy policies are embedded in social, historical and cultural practices and need to take a broader perspective than either technological fixes or a narrowly defined goal of low or zero carbon emissions to be fair and effective. We argue that this is often not reflected in the EU's energy policy frameworks, and use the Energy Roadmap 2050 to demonstrate our point. Contrary to the impression given by the roadmap, a narrow technocratic empirical basis for a policy is not enough to define and solve an energy problem. Energy issues are societal problems and need to be addressed as such.

  • 124256.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    A Gap in the Grid: Attempts to introduce natural gas in Sweden 1967-19912013Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis follows the process of introducing natural gas in Sweden and the construction of a Northern European gas grid from 1967 to 1991. Natural gas is a relatively unnoticed fuel in Sweden today, but this relative anonymity stands in contrast to an extensive historical activity that has taken place behind the scenes of Swedish energy policy. The single pipeline constructed between Denmark and Sweden in the early 1980s was both preceded and followed by many other attempts to construct a larger natural gas pipeline in the region made in the last 50 years. Åberg traces these attempts while discussing the complex and messy process of constructing and managing a transnational energy infrastructure.Åberg follows actors in Sweden and other countries in their attempts to negotiate and construct a natural gas infrastructure, and puts this process into a national as well as transnational context. The perceived risks and opportunities surrounding natural gas are examined, together with factors that have influenced the development of natural gas in a broader sense. By seeing the changing and messy natural gas projects as arenas where different actors construct and negotiate risks and opportunities, as well as contexualize the projects, Åberg shows how the natural gas sector in Sweden has evolved and taken shape.The study shows that natural gas in Sweden has suffered from unstable actor coalitions on different levels, a difficult market situation, and a changeful political context, especially with regard to energy policy. The import status of the fuel and the consequential transnationality of the natural gas infrastructure have also made the process of constructing a pipeline more complex. However, natural gas was introduced in Sweden, showing that when a strong enough actor coalition agreed that there was enough reason to warrant a natural gas introduction and was ready to join this endeavor, a connection could be achieved. This puts into question to what degree general explanations in terms of finance and policy drive energy decisions, and makes a case for showing how these explanations are adapted into their social and historical contexts in sometimes surprising ways.

  • 124257.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Dealing with sea monsters: On gas grids, relative risk and transnational trust2011Conference paper (Other academic)
  • 124258.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Dragkampen om naturgasen2009Conference paper (Other academic)
  • 124259.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Naturgasen som krishantering: Svensk energipolitik i spåren av energikriserna2011Conference paper (Other academic)
  • 124260.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Negotiating Neighbours: National and transnational politics of a natural gas pipeline2009Conference paper (Other academic)
  • 124261.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Negotiating risk: The Swedish – Danish gas deal2008Conference paper (Other academic)
  • 124262.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Saviour or Villain?: Natural gas and the fear of energy shortage in Sweden 1967-19912013Conference paper (Refereed)
    Abstract [en]

    The Nord Stream pipeline, inaugurated in 2011, stretches from Russia through the Baltic Sea down to German shores providing Western Europe with one more import route for natural gas from Russia. The decision by the Swedish government to allow this Russian-German pipeline to pass over Swedish sea territory was lively debated and this debate can be said to have highlighted Swedish (mostly negative) attitudes towards its great eastern neighbour as well as toward natural gas as an energy resource. Some have claimed that the reason for Sweden’s negative view of the pipeline project has to do with a lingering Swedish fear of the Russians, a heritage from the Swedish-Russian wars in the 16th and 17th centuries (Savic, 2012). The Swedish relation to both natural gas and to Russia/the Soviet Union, however, is quite a complicated one deserving to be examined more closely.

    During more than 20 years, between 1967 and 1991 Swedish actors tried in different ways to secure a natural gas import contract with the Soviet Union. At that time, the fear was not so much the Russians as the possibility of energy shortage found at the core of much energy policy in the 20th century. Alongside this fear of energy shortage was a fear of entering into a strong energy dependence. Natural gas was one way to counter the energy shortage, but it was also a particularly risky energy source, since the material and organisational structure of a gas pipeline leads to a quite rigid, long term commitment.

    In this context, natural gas was pointed out as both savior and villain, and in my paper I will examine how the actors navigated between these two extremes. Was natural gas as an energy source considered more risky than other sources? Were certain actors considered more dangerous to enter into agreement with than others? How did these attitudes change over time? Exploring the actors’ hopes and fears in regards to natural gas, as well as the contexts that shaped them, might shed a different light on Swedish energy policy in the end of the 20th century as well as on the view of Swedish-Soviet relations.

  • 124263.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    The Dawning of the Cyborg has arrived2013Conference paper (Refereed)
    Abstract [en]

    In this paper I analyze a biomechanical prosthetic arm and the changing meanings and roles given to this artifact on different arenas. In 2003 Jesse Sullivan became the first man in the world to get a biomechanical arm prosthetic; a robotic arm connected directly to his nerve system and directed by brain impulses in a similar way as an organic arm. In 2005 Claudia Mitchell became the first woman to get the same type of arm. Jesse, Claudia and their arms were widely mediated, and many called them “the world’s first cyborgs”. The cyborg concept in itself dates back to the 1960s, but the idea of a fusion between man and machine has been a recurrent theme in scientific research, engineering and fictional narrative over time. To many observers, Jesse and Claudia seemed to finally embody this fusion.

    The bionic arm is deeply inscribed in earlier narratives of machine-human interaction, but can also be connected to many other contexts. It is a prosthetic, and one of its functions is to restore a body to its “normal” or rehabilitated state. This makes it an interesting ground for analysis regarding what is considered “normality” in regards to bodies and functions. Further, the arm is a product of military research as a help for wounded soldiers, and at the same time inscribed in a context of weapon production and the possibility to make more effective soldiers. All these interests and narratives meet in the research communication around the bionic arm.

    Research on the relation between media and science has underlined that researchers in the media have mixed purposes - to win public acceptance, political support, financial resources, or even personal fame (Weingart, 1998). Medial presence can also be used to create an air of doubt around a technology or a scientific finding (Cf Oreskes & Conway, 2010). It has also been pointed out that the process of legitimitizing new innovations through medial presence has become more complicated with the arrival of the Internet and new social media(Elam, 2004). The case of the bionic arm gives me a possibility to study this process and the actors involved: Engineers, Financiers, Journalists and “the Public.

    My study takes as its departure four different levels of the communication around the bionic arm: Public communication from engineers and researchers, from the military, from daily press and from blogs/commentators. These four types of source material represent different interpretations of what the biomechanical arm is and the actors that communicate around the arm have to relate to already existing images of what the connection between man and machine means as well as inscribe the arm in a history of medical engineering, disability, war, science fiction, gender and everyday life. My questions regard the interplay between these narratives, as well as the practical implementations they cause. Who has the power to decide what a technology “means”? Who gets to speak for a certain technology? And which narratives become important when we interpret new technologies?

  • 124264.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    The Power of vision: Natural Gas fiction and the Decision Making Process2012Conference paper (Other academic)
    Abstract [en]

    In the energy debate, energy carriers are often perceived as either saviours or villains, but most often as both. Fossil fuels power a large part of our society, but they also pollute and are sometimes extracted at large human costs. Nuclear power is efficient and powerful, but the consequences of using it could be potentially fatal. Ethanol is environmentally friendly, but may have negative societal consequences. The energy issue is a jungle of pros and cons, a jungle in which we have to navigate in order to make decisions about what we want our future to look like. Often, these decisions are informed by future visions in the form of scenarios, prognosis, and forecasts. In this paper, I will look at how politicians, engineers and other Swedish actors have navigated this jungle regarding the issue of natural gas in Sweden. This will lead me into the question of how decision-making regarding energy has been handled from the late 1960s to the 1980s, in a time when the future of our energy systems became more and more of an obsession for politicians and lay people alike.

     

    Although natural gas has never been a major fuel in Sweden, its presence has been steady in the energy debate for over 40 years. Especially during the 1970s and 1980s it was part of the plans to create a more sustainable national energy system. Natural gas was thought to become widely introduced in Sweden, and engineers, economics and civil servants were involved in an endless discussion regarding the pros and cons of the fuel. Further, the late 1960s and early 1970s was a time when future studies was forming itself as a field, and energy scenarios became more commonly used as one of the factors of decision-making. I want to couple these two processes together, and look at how energy scenarios were used by engineers and groups of interest over time when trying to influence politicians and navigate the process of introducing a new, unknown energy carrier into Sweden.

     

    This story raises several important issues. First of all, it can help us understand the role played by forecasts and scenarios in the decision-making process. The relation between visions of the future and our decision-making today is complex, and needs to be thoroughly analyzed and put in a historical perspective. Another issue regards the actors involved. Who used these future scenarios, and to what end?  Did the Swedish engineers and politicians gather around visions of a future natural gas infrastructure, or did they have diverging thoughts regarding what is a desirable development would be? In what way has different future scenarios been used as a power tool in the political decision-making surrounding energy issues?

     

    In my work I draw on literature regarding the relationships between engineers and politicians, and the influence of engineers on policy (Jasanoff, Hecht, Hughes, Micheletti, Sejersted, etc.). I aim to add to this literature by examining the practicalities of how actors try to gain power over the energy issue, using future visions as a tool. In doing this I also hope to contribute to the work done on future studies and energy forecasting (Smil, de Man, Baumgartner & Midttun).

  • 124265.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Tillit på prov: Svensk-danska gasförbindelser2008Conference paper (Other academic)
  • 124266.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Two Front Negotiations: the Different Politics of a Natural Gas pipeline2009Conference paper (Other academic)
  • 124267.
    Åberg, Anna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science and Technology.
    Witnessing our energy future2012Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Fossil fuels power a large part of our society, but they also pollute and aresometimes extracted at large human costs. Nuclear power is efficient andpowerful, but the consequences of using it could be potentially fatal.Ethanol is described both as environmental saviour and villain. The energyissue is a jungle of pros and cons in which we need to navigate in order tomake decisions about what we want our future to look like. One placewhere different ways to navigate the energy dilemma is often discussed is inscience fiction, (i.e the Day of the Triffids, Moon, the Matrix) and I want toexplore some of these narratives and the way they handle the issue overtime. Science fiction has for the past 100 years been a platform wheresocietal issues have been been brought out to the public, discussed, andinterpreted. But what can we learn from looking at the energy issue from ascience fiction perspective? How can we go further than a mere text/imageanalysis? Are there threads leading from fictional narratives into the “real”world, and what do these threads look like? Can popular culture expressionshelp us decide anything about our future, and in that case, is it possible tofind out how?

  • 124268.
    Åberg, Anna Cristina
    et al.
    Swedish School of Sports and Health Sciences.
    Frykberg, Gunilla
    Uppsala University.
    Halvorsen, Kjartan
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 4, p. 438-443Article in journal (Refereed)
    Abstract [en]

    Most falls in older people are due to loss of balance during everyday locomotion, e.g., when initiating walking from sitting; sit-to-walk (STW). It has been considered that the broader stride width in walking that is seen in many people with fear of falling (FoF) does not increase stability, but could be predictive of future falls because of increased medio-lateral (ML) velocity of the body centre of mass (CoM). This study was aimed to examine step-, velocity- and stability-related parameters, focusing on ML stability, in STW performance of people with and without FoF. Ten subjects with FoF and 10 matched controls, aged >= 70 years, were included. Kinematic and kinetic data were collected in a laboratory. Stability parameters were calculated from a formula implying that the vertical projection of the CoM extrapolated by adding its velocity times a factor root l/g (height of inverted pendulum divided by gravity) should fall within the base of support (BoS). A related spatial margin of stability (SMoS), defined as the minimum distance from the extrapolated CoM (XCoM) to the boundaries of the BoS, was also calculated. In the phase 'seat-off-second-toe-off, the FoF group had significantly (p < 0.05) shorter and broader steps, lower forward but similar ML CoM velocity, and broader CoM and XCoM widths. The FoF group therefore exhibited a disproportionately large sideways velocity compared to the controls. This indicates that STW may be a hazardous transfer for older people with FoF, which should be relevant in assessment and training aimed at preventing falls.

  • 124269.
    Åberg, Anna
    et al.
    Chalmers.
    Höffken, Johanna
    Eindhoven University of Technology.
    Lidström, Susanna
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Looking for Perspectives!: EU Energy Policy in Context2018In: Advancing Energy Policy: Lessons on the Integration of Social Sciences and Humanities / [ed] Chris Foulds and Rosie Robison, Palgrave Macmillan, 2018Chapter in book (Refereed)
    Abstract [en]

    Transitioning to less carbon-intensive energy systems involves making difficult choices and priorities. This chapter imagines three individuals who are affected in different ways by EU energy policy. Their fictional stories illustrate that energy policies are embedded in social, historical and cultural practices and need to take a broader perspective than either technological fixes or a narrowly defined goal of low or zero carbon emissions to be fair and effective. We argue that this is often not reflected in the EU's energy policy frameworks, and use the Energy Roadmap 2050 to demonstrate our point. Contrary to the impression given by the roadmap, a narrow technocratic empirical basis for a policy isnot enough to define and solve an energy problem. Energy issues are soci-etal problems and need to be addressed as such.

  • 124270.
    Åberg, Anna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Lidström, Susanna
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Rising Seas: Facts, Fictions and Aquaria2013Conference paper (Refereed)
    Abstract [en]

    Rising Seas: Facts, fictions and aquaria While exhibiting ocean environments presents particular practical difficulties to most museums, rising sea levels and other drastic changes in the sea make the ocean an essential part of any exhibit on climate change. This paper will examine how aquaria and other museums interpret and showcase ocean science in their attempts to imagine a warmer future world.To do this, we will look at a few specific cases of representations of the ocean in climate change exhibits. How is the sea represented or showcased? What kinds of artefacts are used? What narratives accompany the representation? Is the ocean presented as an alien environment, or is it shown to be permeated by pollution and other signs of human presence? Is it meaningful to talk about 'the ocean' as one place, or do we need to refer to specific places or habitats, differentiating between shallow seas with coral reefs and familiar species and the less well-known deep oceans, for instance? Based on these case studies, we will attempt a more general discussion and analysis of the role of future visions for imagining what a marine Anthropocene might look like and how they can be exhibited in the context of local and global climate change.

  • 124271.
    Åberg, Denny
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Capacitance Spectroscopy of Point Defects in Silicon and Silicon Carbide2001Doctoral thesis, comprehensive summary (Other scientific)
  • 124272.
    Åberg, Denny
    KTH, Superseded Departments, Electronic Systems Design.
    Oxygen related thermal donors in silicon1998Licentiate thesis, comprehensive summary (Other scientific)
  • 124273.
    Åberg, Elina
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Agricity2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    10 billion people will inhabit this planet by 2050. In order to feed such a large number of people research shows that food production will need to increase by 70%.This project explores what a foodcentric city planning can look like, where agriculture is not only integrated into the built environment, but rather the main generator of urban form. A block typology specifically tailored to create optimal growing conditions is rolled out as a high density agricultural grid across Bromma airport, and addresses issues of combining large scale structures with small scale human life.

  • 124274.
    Åberg, Elina
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Det halvt dolda2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project aims att designing a hotel with 34 rooms on the outskirts of the small historic town of Mariefred, situated on the shores of Lake Mälaren. The hotel consists of a square volume with brick facade and a distinguished chamfered corner, the flat plot is next to the local railway museum. Ancient Gripsholm castle dominate the town, and the hotel's placing on the plot preserves important sight lines. The program includes key features such as hotel rooms, lobby and restaurant, and also a movie theater in the ground floor. The interior of the hotel is dominated by a staircase set on the diagonal, which creates an uninterrupted flow of natural light through the building and points your attention inward, upward from the main entrance. The main movement between floors is done here. There are also a whole other layer of the building, addressed to children. Children are given great space and a network of secret passages, covert connections, where they are to be invited to play and discover, far from controlling adult eyes. The passages are accessed directly from every room through ladders and small doors, and are visible in the facade through a string of small windows at different heights, which also provides facade decoration. In the hotel there is a variety of small nooks and secret rooms to find, hiding places to create a trip during the trip.

  • 124275.
    Åberg, Erik
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Review of an industrially implemented model of zoning principles for electricity distribution and energy production2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The interconnection of components of industrial automation and control systems (IACS) and enterprise systems involved in processes ranging from generation and transmission to billing within electric utilities poses challenges regarding cyber security as well as division of organisational responsibility. One means of organising these components and systems is to use a zone model in which they are segmented, offering layered defences as well as a logical grouping. One such zone model is the zone model under review, which was presented by Zerbst et al. in a CIRED paper from 2009. This master thesis reviews that zone model and compares it to other industry standard zone models which have been found to be able to be categorised into either functional based models or layered defence models. The outcome is a rough definition of what kind of content fits in the various zones of the reviewed model, as well as a normalised zone model to be used for comparison. A suggested method for dividing system components into zones is based on the 4R-method considering the response time, resolution, reliability and reparability of the system component, although its accuracy has not been empirically tested.

  • 124276. Åberg, J.
    et al.
    Persson, S
    Hellberg, P.-E.
    Zhang, S.-L.
    Smith, U
    Ericsson, F
    Engström, M
    Kaplan, W
    Electrical properties of the TiSi2-Si transition region in contacts: The influence of an interposed layer of Nb2001In: Journal of Applied Physics, Vol. 90, p. 2380-2388Article in journal (Refereed)
  • 124277. Åberg, J.
    et al.
    Vynnycky, M.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Heat-flux measurements of industrial on-site continuous copper casting and their use as boundary conditions for numerical simulations2009In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 62, no 4-5, p. 443-446Article in journal (Refereed)
    Abstract [en]

    An embedded sensor, designed for rapid and accurate response times and using wireless data transmission, has been developed for the on-site measurement of temperatures in industrial continuous casting moulds. The sensor has been used to measure the temperature at several points in the mould during production in a Southwire copper casting process. The measured data has been used to calculate the temperature gradient in the mould to estimate the heat flux through it; this is then used as a boundary condition for numerical simulations of solidification. For these, we employ a method that tracks the solidification front explicitly; this has an advantage over fixed-grid methods in simulations for materials having a short solidification interval, since the release of latent heat at the solidification front can be resolved without resorting to a very fine mesh. The special considerations required for setting the initial condition for the numerical scheme and the time taken for the superheated melt to form a solid shell are also discussed.

  • 124278.
    Åberg, Jenny
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Möjligheter och hinder för det förebyggande arbetsmiljöarbetet: En intervjustudie med en enhet på Feelgood Företagshälsa och två av deras kundföretag inom byggbranschen.2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: The occupational health services (OHS) in Sweden is provided as an impartial expert advice to client companies and shall identify and explain the relationship between work, organization, productivity and health. In general, client companies use the occupational health services particularly for reactive services, when illness has already occured in the company. Construction workers staying constantly in a hazardous environment and are exposed to heavy lifting, monotonous movements and bad working positions. It is therefore important to examine how occupational health can contribute to the preventive work environment for client companies to meet the challenges of the construction work.Aim: The aim of the study was to investigate the opportunities and barriers that exist to the preventive work of occupational health services.Method: A literature review and an interview study was conducted in spring 2013. Scientific papers and other documents were obtained through databases available through the libraries at the Royal Institute of Technology, University of Gothenburg and Halmstad University. Ten individual semi-structural interviews were carried out with a safety engineer and an account manager at a Feelgood unit, as well as with supervisors, safety representatives and with people who had an HR and working position on two of Feelgoods client companies in the construction industry.Results: The analysis revealed eight themes that represented opportunities and barriers to preventive work environment: consultative approach, systematic work environment management, workplaces visits, competence, marketing and communication, management, lack of coordination between professions in occupational health services and customer agreement.Conclusion: The occupational health service needs to take greater responsibility in preventive work environment and challenging client companies to advise them in good working solutions. Occupational health services also needs to be better at marketing their business to client companies to know what they can use OHS for. Feelgood are professional and have high competence in the individual conversations but can improve their professional skills at organizational level. The client companies demand field visits and they saw that OHS has a role in performing technical measurements and help in the process of job rotation. Preventive health services should be written into the agreement in order to be utilized to a greater extent.

  • 124279.
    Åberg, Joakim
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Bergsklättraren2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mouanten Climber

    The project is about a building typology produced to facilitate a aggressive topology. To accommodate the special circumstances of the site, the building must climb alongside a steep mountainside. There fore the wooden houses are specially designed for this task. Trough a series of tests at module house that will be easy to produce will be able to adopted in to this special environment.

  • 124280.
    Åberg, Jonas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    On the Experimental Determination of Damping of Metals and Calculation of Thermal Stresses in Solidifying Shells2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis explores experimentally and theoretically two different aspects of the properties and behaviour of metals: their ability to damp noise and their susceptibility to crack when solidifying.

    The first part concerns intrinsic material damping, and is motivated by increased demands from society for reductions in noise emissions. It is a material’s inherent ability to reduce its vibration level, and hence noise emission, and transform its kinetic energy into a temperature increase. To design new materials with increased intrinsic material damping, we need to be able to measure it. In this thesis, different methods for measurement of the intrinsic damping have been considered: one using Fourier analysis has been experimentally evaluated, and another using a specimen in uniaxial tension to measure the phase-lag between stress and strain has been improved. Finally, after discarding these methods, a new method has been developed. The new method measures the damping properties during compression using differential calorimetry. A specimen is subjected to a cyclic uniaxial stress to give a prescribed energy input. The difference in temperature between a specimen under stress and a non-stressed reference sample is measured. The experiments are performed in an insulated vacuum container to reduce convective losses. The rate of temperature change, together with the energy input, is used as a measure of the intrinsic material damping in the specimen. The results show a difference in intrinsic material damping, and the way in which it is influenced by the internal structure is discussed.

    The second part of the thesis examines hot cracks in solidifying shells. Most metals have a brittle region starting in the two-phase temperature range during solidification and for some alloys this region extends as far as hundreds of degrees below the solidus temperature. To calculate the risk of hot cracking, one needs, besides knowledge of the solidifying material’s ability to withstand stress, knowledge of the casting process to be able to calculate the thermal history of the solidification, and from this calculate the stress. In this work, experimental methods to measure and evaluate the energy transfer from the solidifying melt have been developed. The evaluated data has been used as a boundary condition to numerically calculate the solidification process and the evolving stress in the solidifying shell. A solidification model has been implemented using a fixed-domain methodology in a commercial finite element code, Comsol Multiphysics. A new solidification model using an arbitrary Lagrange Eulerian (ALE) formulation has also been implemented to solve the solidification problem for pure metals. This new model explicitly tracks the movement of the liquid/solid interface and is much more effective than the first model.

  • 124281.
    Åberg, Jonas
    KTH, Superseded Departments, Production Engineering.
    On the Experimental Determination of Material Damping in Metals2001Licentiate thesis, comprehensive summary (Other scientific)
  • 124282.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    An On-site Industrial Experimental Heat Flux Study during Solidification of Pure Copper in the Southwire Process2007In: T INDIAN I METALS, ISSN 0972-2815, Vol. 60, no 2-3, p. 191-196Article in journal (Refereed)
    Abstract [en]

    To study the production of pure copper and copper alloys in the Southwire process the temperature in the mould has been measured on-site in the production process in a number of positions. To increase the accuracy and robustness of measurements a new type of thermocouple based temperature sensor has been developed and tested. The test system includes wireless transmission of measured data from the moving mould. The results from the measurements are then used to calculate the energy transfer rate from the solidifying shell as a function of time. An initial in-situ measurement campaign has been performed and the results are very promising.

  • 124283.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vynnycky, Michael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Modelling of Thermal Stresses in Industrial Continuous Casting Processes2005In: Proceedings of the Femlab Conference, Stockholm, 2005Conference paper (Refereed)
    Abstract [en]

    This paper reports on progress in the implementationof COMSOL Multiphysics 3.2 to model thermalstresses in a three-dimensional solidifying shell, asoccurs typically in the industrial continuous casting ofcopper, copper alloys and steel. Computer memory requirementsprohibit a direct 3D numerical simulation ofthe temperature and the stresses. Instead, we use the factthat casting geometries are usually slender to divide thecalculation into three steps that are each less memoryintensive:(i) heat transfer and solidification is simulatedusing an arbitrary Lagrangian-Eulerian model; (ii) thetemperature solution is used to solve the force equilibriumequations in generalised plane strain mode appropriatefor a moving body; (iii) this solution is used tocompute the accumulated stress and strain in the body.Comparison between an analytical solution and a numericalsolution, that requires the simultaneous use ofseveral of Comsol Multiphysics’ peripheral features, ispresented.

  • 124284.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vynnycky, Michael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nassar, Hani
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bergström, Thomas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    An on-site experimental heat flux study and its interpretation in a FEMLAB finite element simulation of continuous casting of copper in the South-Wire process2005In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 58, no 4, p. 509-515Article in journal (Refereed)
    Abstract [en]

    The South-Wire process, a development of the Properzi process, to continuously cast copper has been studied both experimentally and by finite element computer simulation. The experimental work has been performed on site to get temperature data as a function of time at several locations within the mould. These experimental data have been used to evaluate boundary conditions for the heat transfer from the strand-mould interface and through the mould. A simulation model of the casting process has been developed in the program FEMLAB. In this program temperature varying material data and time varying boundary conditions have been used. The simulation model has been verified by comparing with an analytical solution, and then applied to the real physical process.

  • 124285.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Vynnycky, Michael
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Widell, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Development of a finite element model for study of the developing stress and strain in a solidifying shell2006Report (Other academic)
  • 124286.
    Åberg, Jonas
    et al.
    KTH, Superseded Departments, Materials Processing.
    Widell, Björn
    KTH, Superseded Departments, Casting of Metals.
    Uniaxial material damping measurements using a fiber optic lattice: a discussion of its performance envelope2004In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 44, no 1, p. 33-36Article in journal (Refereed)
    Abstract [en]

    Damping is the internal transfer of kinetic energy to other forms of energy. Today, most methods use either bending or torsional vibration to measure damping. This means that the strain field in the specimen is nonhomogeneous. If the damping of the tested material is linear, strain-independent, the values acquired with these traditional methods will be equal to the intrinsic material damping of the material. If, however, the damping is strain-dependent, nonlinear, the measured value will be an average of the damping of the specimen, and not equal to its intrinsic material damping. To address this problem, a method is required to experimentally determine the damping in uniaxial tension in order to produce the same strain level in all parts of the test specimen and hence obtain a measurement of the intrinsic material damping. Using such a method, it is possible to view the material damping as the phase angle between the stress and the strain in a harmonic oscillation. In this paper, a method is suggested for measuring this phase shift in uniaxial tension to determine the material damping properties. It uses a tensile test machine, an optical fiber Bragg grating technique and a lock-in amplifier. Measurements with the phase shift technique have been suggested previously, but its performance envelope has been overestimated. In this paper, the performance envelope is discussed and restricted. It is shown that the envelope depends on the specimen length, loss factor and test frequency. An optical strain measurement method is also believed to help avoid many electrical measurement problems seen with the originally proposed method.

  • 124287.
    Åberg, Jonas
    et al.
    KTH, Superseded Departments, Casting of Metals.
    Widell, Björn
    KTH, Superseded Departments, Casting of Metals.
    Bergström, Thomas
    KTH, Superseded Departments, Casting of Metals.
    Fredriksson, Hasse
    KTH, Superseded Departments, Casting of Metals.
    Measurement of intrinsic material damping using differential calorimetry on specimens under uniaxial tension2004In: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 411, no 2, p. 125-131Article in journal (Refereed)
    Abstract [en]

    A method has been developed to measure the intrinsic damping capacity of metals. A specimen is subjected to a cyclic uniaxial stress, to give a prescribed energy input. The amount of energy that is stored in the specimen is measured using differential calorimetry, i.e. the difference in temperature between the specimen under stress and a non-stressed reference sample is measured. The experiments were performed in an insulated vacuum container to reduce convective losses. The heating rate, together with the energy input, is used as a measure of the intrinsic material damping in the specimen. The method has been developed by testing an aluminium based and a stainless steel alloy. It is possible to distinguish the difference in damping between these two alloys.

  • 124288.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Widell, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Fredriksson, Hasse
    Intrinsic Material Damping in Mg, Al and Fe Alloys and a Discussion of its Dependence on the Internal Structure of the Material2006Report (Other academic)
  • 124289.
    Åberg, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Widell, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Larsson, Petra
    Investigation of the Damping in Twelve Metallic Plates Using Frequency Response2006Report (Other academic)
  • 124290.
    Åberg, Lena Magnusson
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vinet, Bernard
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Heat of Solidification in Refractory Metals Studied by Drop-Tube Experiments2009In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 62, no 4-5, p. 269-273Article in journal (Other academic)
    Abstract [en]

    A number of pure refractory metals have been investigated by drop-tube experiments. The cooling curves have been registered and theoretically analysed. A model for analysing the heat of fusion has been developed. It was found that the heat of fusion was approximately 50% of the tabulated value.

  • 124291.
    Åberg, Linus
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Utveckling av hygienfunktioner i diskmaskiner: Desinfektion med hjälp av UV-ljus och ozon2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis within the field of Integrated Product development at the Royal Insitute of

    Technology, performed at Primary Development Dishcare at AB Electrolux, is supposed to find

    a solution to enhance the hygiene inside an Electrolux dishwasher. The outcomes of this thesis

    are functional prototypes to evaluate the efficiency of disinfection by the use of Ultra Violet

    Light and Ozone.

    The thesis has followed Electrolux Primary Development process, with delivarables and

    checkpoints.

    Ultra violett light with a wavelength of around 264 nm penetrates through the cell wall of

    bacteria and micro organisms and causes a molecular rearrangement of the cells DNA. This

    prevent the bacteria from reproducing and it is considered dead. Commonly used UV-C lamps

    transmits the wavelength 254 nm which is very close to the optimum for germicidal action.

    A competitive brand have reacently launched a dishwasher claiming to achieve greater

    disinfection with an UV feature. This dishwasher was tested during the thesis and proven to

    have a very low effect on the hygienic result.

    Two prototypes were devolped and tested for UV disinfection of dishware. It was found that UV

    will only kill bacteria that is in direct contact with the UV irradiation. This makes an UV feature

    unfeasible for a dishwasher due to the complex arrangement of dishware. However may an UV

    feature enhance the percieved hygienic result of the dishwasher and therefore act as a marketing

    feature.

    Ozone can also be used for killing micro-organisms in air and water, several possibilities can be

    seen. It could be possible to save water from the last rinse and treat it with ozone or UV to

    prevent bacteria growth. The water may also be treated within the dishcycle and therefore

    decrease the need of detergent.

  • 124292.
    Åberg, Ludvig
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Multimodal Classification of Second-Hand E-Commerce Ads2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In second-hand e-commerce, categorization of new products is typically done by the seller. Automating this process makes it easier to upload ads and could lower the number of incorrectly categorized ads. Automatic ad categorization also makes it possible for a second-hand e-commerce platform to use a more detailed category system, which could make the shopping experience better for potential buyers. Product ad categorization is typically addressed as a text classification problem as most metadata associated with products are textual. By including image information, i.e. using a multimodal approach, better performance can however be expected. The work done in this thesis evaluates different multimodal deep learning models for the task of ad categorization on data from Blocket.se. We examine late fusion models, where the modalities are combined at decision level, and early fusion models, where the modalities are combined at feature level. We also introduce our own approach Text Based Visual Attention  (TBVA), which extends the image CNN Inception v3 with an attention mechanism to incorporate textual information. For all models evaluated, the text classifier fastText is used to process text data and the Inception v3 network to process image data. Our results show that the late fusion models perform best in our setting. We conclude that these models generally learn which of the baseline models to ’trust’, while early fusion and the TBVA models learn more abstract concepts. As future work, we would like to examine how the TBVA models perform on other tasks, such as ad similarity.

  • 124293. Åberg, M.
    et al.
    Lingfors, D.
    Olauson, Jon
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Widén, J.
    Can electricity market prices control power-to-heat production for peak shaving of renewable power generation?: The case of Sweden2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 176, p. 1-14Article in journal (Refereed)
    Abstract [en]

    100% renewable energy systems require high penetration of variable renewable electricity (VRE) generation. This causes the net load in the system to be more variable and could cause operational problems in local power grids. Demand side management (DSM), such as fuel or energy carrier switching in response to a price signal, can provide flexibility to meet the increased variability. This study investigates the impact of VRE production on electricity prices and their potential to act as an incentive to control district heating power-to-heat (P2H) production in order to shave VRE production peaks. Also, the potential to increase P2H production flexibility with additional heat storages is studied. Electricity prices are simulated by modification of historical electricity market supply curves. A heat storage component is implemented in an existing model for district heat production. The results show that P2H production is significantly increased (up to 98%) when electricity prices are influenced by VRE production. Thermal storages further increase the P2H production by up to 46%. The increased P2H production, however, does not necessarily coincide with the peaks of VRE. Thus, in conclusion, the pricing mechanism on the Nord pool electricity market is insufficient to control P2H production for shaving VRE production peaks.

  • 124294.
    Åberg, Mats
    KTH, Superseded Departments, Solid Mechanics.
    Modelling of microstructural effects on wave propagation in composites1997Licentiate thesis, comprehensive summary (Other scientific)
  • 124295.
    Åberg, Mats
    KTH, Superseded Departments, Solid Mechanics.
    Wave propagation and damage in composite laminates1999Doctoral thesis, comprehensive summary (Other scientific)
  • 124296.
    Åberg, Mats
    et al.
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Acoustic emission in laminated beams due to fiber fractures1999In: Twelfth Int. Conf. on Composite Materials, ICCM-12, Paris, pap501, 1999, 1999Conference paper (Refereed)
  • 124297.
    Åberg, Mats
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    Dispersion of waves in composite laminates with transverse matrix cracks, finite element and plate theory computations1998In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 65, no 3, p. 588-595Article in journal (Refereed)
    Abstract [en]

    Dispersion relations for laminated composite plates with transverse matrix cracks have been computed using two methods. In the first approach it is assumed that the matrix cracks appear periodically and hence it is possible to consider a periodic cell of the the structure using Bloch-type boundary conditions. This problem was formulated in complex notation and solved in a standard finite element program (ABAQUS) using two identical finite element meshes, one for the real part and one for the imaginary part of the displacements. The two meshes were coupled by the boundary conditions on the cell. The code then computed the eigenfrequencies of the system for a given wave vector. It was then possible to compute the phase velocities. The second approach used may be viewed as a two step homogenization. First the cracked layers are homogenized and replaced by weaker uncracked layers and then the standard first-order shear-deformation laminate theory is used to compute dispersion relations. Dispersion relations were computed using both methods for three glass-fiber/epoxy laminates ([0/90](2), [0/90](2) and [0/45/-45](s) with cracks in the 90 and +/-45 deg plies). For the lowest flexural mode the difference in phase velocity between the methods was less then five percent for wavelengths longer than two times the plate thickness. For the extensional merle a wavelength of ten plate thicknesses gave a five percent difference.

  • 124298.
    Åberg, Mats
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    Micromechanical modeling of transient waves from matrix cracking and fiber fracture in laminated beams2000In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 37, no 30, p. 4083-4102Article in journal (Refereed)
    Abstract [en]

    A micromechanical model for excitation of waves resulting from fiber fracture and matrix cracking in laminated beams is presented. The source is described as a time dependent displacement discontinuity and the wave propagation in the beam is modeled by a higher-order beam theory. The equations of motion defined by the beam model are then formally solved by employing integral transforms. Asymptotically valid solutions are subsequently found using residue calculus and the stationary phase method. As an example, a [90/0(2)/90] beam with a width to thickness ratio of 10 is considered. The dispersion curves resulting from the beam theory and three-dimensional finite element computations are compared and a maximum frequency for applicability of the beam theory is determined. The time response from fiber fracture and transverse matrix cracking is presented. The applications of the results to the analysis of acoustic emission experiments are also discussed.

  • 124299.
    Åberg, Mats
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    The usage of standard finite element codes for computation of dispersion relations in materials with periodic microstructure1997In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 102, no 4, p. 2007-2013Article in journal (Refereed)
    Abstract [en]

    A method with which standard finite element programs can be used to compute dispersion relations in periodic composites is proposed. The method is applied to two composite microstructures: a two-phase laminate and a fiber composite. The dispersion relations computed for the laminate are compared with a known analytical solution and the agreement is very good. The dispersion relations computed for the fibrous composite are compared with an existing approximate model and experimental results from the literature. The agreement between the approximate model, the experiments, and the computations is very good in the wave guide case and satisfactory for the wave reflect case.

  • 124300.
    Åberg, Måns
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Fridh, Gustav
    KTH, School of Computer Science and Communication (CSC).
    Plattformsbaserat samarbete inom matematik2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mathematics Courses at the Royal Institute of Technology (KTH) are each year taken by several thousand students. The throughput is low relative to other courses and to increase the proportion of students who pass the courses without reducing the requirements lies in both the students and teachers interest.In this thesis, we investigate what platforms for cooperation in mathematics today's students at the Media Technology Programme, Royal Institute of Technology, uses, how they are used and how the various platforms are perceived to affect students' ability to learn in mathematics. This is relevant since the courses in mathematics are considered to be the most difficult at KTH. To answer the question we asked 20 students to fill in a survey. The answers were mostly in free-text form.The results show that students uses Facebook,Skype, Mathoverflow and Reddit for cooperation in mathematics. These platforms are used when students find something difficult in the mathematic courses, and want to discuss solutions with other students. Platforms like Youtube, WolframAlpha and Ludu are, according to the students, being used for cooperation in mathematics. However, we believe that these platforms do not fall under our term of platform-based cooperation. A majority of respondents believe that there are enough resources at KTH to help them with their ability to learn mathematics. If KTH would introduce a platform to facilitate learning in mathematics most wish that it would contain a discussion forum where students and teachers could help each other with solutions to mathematical problems

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