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  • 1. Adolfsson Boman, Marianne
    et al.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Hverven, Mona
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Jansson, Anders
    Stockholm University, Faculty of Social Sciences, Department of Special Education.
    Tambour, Torbjörn
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Att introducera likhetstecken i ett algebraiskt sammanhang för elever i årskurs 12013In: Forskning om undervisning och lärande, ISSN 2000-9674, E-ISSN 2001-6131, no 10, p. 29-49Article in journal (Refereed)
    Abstract [sv]

    Artikeln bygger på data från forsknings- och utvecklingsprojektet (FoU) ”Utveckling av matematiskt tänkande – expanderande uppgifter i nybörjarundervisningen” där lärare från Skärsätra skola tillsammans med forskare från Stockholms universitet genomförde ett undervisningsexperiment i syfte att introducera algebra i nybörjarundervisningen.

  • 2.
    Andrée, Maria
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Eriksson, Inger
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    A research environment for teacher-driven research - some demands and possibilities2019In: International Journal for Lesson and Learning Studies, ISSN 2046-8253, E-ISSN 2046-8261, Vol. 9, no 1, p. 67-77Article in journal (Refereed)
    Abstract [en]

    Purpose The purpose of this paper is to reflect upon demands of and possibilities for establishing a space for conducting and supporting high-quality research in schools. In the article the authors reflect upon experiences in establishing a research environment for teachers called Stockholm Teaching & Learning Studies (STLS). The article focusses some of the tensions that have been emerging in attempting to build an infrastructure for teacher-driven research and discusses the transformative potential of those tensions. Design/methodology/approach The article draws on the authors' experiences in establishing STLS as a research environment for teachers by drawing on a framework of cultural-historical activity theory. The article applies the notions of contradictions and tensions as driving forces for development of activity. Findings The specific tensions that have been negotiated in the establishment of STLS are tensions between developing public knowledge vs local knowledge, tensions in knowledge cultures between oral and text-based ways of sharing knowledge, tensions in research interests and tensions in ownership. These tensions relate to knowledge production as embedded in institutional life and constrained by institutional boundaries in contemporary society. Originality/value Today, there is a growing amount of collaborative research that connects elementary and secondary teachers in research projects with university-based researchers. However, this does not guarantee projects that will address everyday problems of teachers or that teachers will be acknowledged as researchers in the end.

  • 3. Bennet, T
    et al.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Haunch, P
    Randle, H
    Learning to become employable by learning to work in the health and social sector. A new career path of life.: Paper to be presented at the International Conference on Workplace Learning - from the Learners´ Perspective, Sub-theme 2: Linking Workplace learning and School-based Learning, Copenhagen, 25-27 nov, 2004.2004Conference paper (Other academic)
  • 4. Berthén, Diana
    et al.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Lindberg, Viveca
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Emerging educational action? BA-Thesis work in maritime higher education2010Conference paper (Refereed)
  • 5.
    Carlgren, Ingrid
    et al.
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    Eriksson, Inger
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    Runesson, Ulla
    Learning study2017In: Undervisningsutvecklande forskning : exemplet Learning study / [ed] Ingrid Carlgren, Malmö: Gleerups Utbildning AB, 2017, p. 17-30Chapter in book (Other academic)
    Abstract [sv]

    Undervisningens kvalitet och hur den ska förbättras har kommit i fokus i debatten om skolan. Ofta diskuteras generella lösningar, till exempel att lärarnas förväntningar på eleverna måste höjas. Undervisning har emellertid alltid ett konkret innehåll och genomförs med specifika grupper av elever. Därför måste förbättring av undervisning alltid utgå från såväl det specifika innehållet som de specifika eleverna.

    Undervisning är lärares professionella verksamhet. Den kan inte standardiseras eller mekaniseras utan måste planeras och genomföras i relation till och i interaktion med den specifika kontexten. I detta arbete behöver lärare kunskaper och teoretiska redskap för att problematisera, analysera och utveckla verksamheten.

    En långsiktig och hållbar utveckling av lärarnas professionella kunskapsbas förutsätter en stegvis och systematisk kunskapsutveckling. I den här boken visas hur en lärardriven och praktiknära forskning kan bidra till att utveckla kunskaper och redskap som kan utveckla undervisningen. Författarna ger exempel på hur forskning kan bidra till att belysa undervisning och lärande på ett sätt som har direkt relevans för lärarnas undervisning.

  • 6. Eriksson, Helena
    et al.
    Eriksson, Inger
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    Matematik som teoretiskt arbete - utveckling av matematiska modeller för rationella tal i åk 42016In: Forskning om undervisning och lärande, ISSN 2000-9674, E-ISSN 2001-6131, Vol. 4, no 1, p. 6-24Article in journal (Refereed)
    Abstract [en]

    The teaching of rational numbers to young students (grade 4-6) is known to be difficult. It is for instance difficult for students to understand that fractions and decimal numbers may represent the same value, or that fraction has a specific place on the number line, i.e. that it is a number among other numbers. The purpose of this article is to discuss and exemplify how students can be involved in a theoretical exploration of fractions as numbers. The basis of the students’ exploration was a designed situation where they were to make measurements of wooden rods where the measurements did not make an equal, i.e. “a little bit” was missing. With these measurements students in joint discussions were able to design a general model for fractions. Such a model could be used as a tool in discussions of “the whole” and “its parts” in fractions. The article is based on data from a series of Learning studies conducted in a grade 4 in an intercultural school in 2012-2013.

  • 7.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Arbetsliv och känsla av sammanhang2004In: Arbetsliv och samhällsförändringar, Lund: Studentlitteratur, 2004, p. 49-60Chapter in book (Other academic)
    Abstract [sv]

    Innehåll: Det goda arbetet, Gemensamma drag, Reflexioner, Elevhälsa, KASAM-modell och dess föregångare, Att få säga sin mening och finna en mening, Attraktiva arbetsplatser

  • 8.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Att fotografera god arbetsmiljö2004In: Bild och samhälle: visuell analys som vetenskaplig metod, Lund: Studentlitteratur, 2004Chapter in book (Other academic)
  • 9.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Dokumentation och utvärdering av MALM-projektet i Sollefteå: Rapport 8: Slutrapport2004Report (Other academic)
  • 10.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    En resa i kaos2001In: På resande fot: 23 forskare skriver om turism och upplevelser., Östersund: ETOUR/Sellins förlag , 2001, p. 126-Chapter in book (Other (popular science, discussion, etc.))
  • 11.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Fjärilar i världen, i organisationen och i magen: Bidrag till Sundsvall 42, Datamässa, 16-18 oktober, 2001, Sundsvall2001Conference paper (Other academic)
  • 12.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Hälsofrämjande skolutveckling: bidrag till konferens om Barns hälsa. Hur möts pedagogik, elevhälsa och hälso- och sjukvård, 16-17 aug, 2004, Sollefteå.2004Conference paper (Other academic)
  • 13.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Kaos och social kompetens2001Book (Other academic)
  • 14.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Konst och vetenskap: Konferens - Föreningen för Fritidstjänstemän inom omsorg/handikapp2002Conference paper (Other academic)
  • 15.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Kundkontakt. Dokumentation och utvärdering av MALM-projektet.2001In: Rapport 2: Första Callcenterprojektet, November 2001, Sundsvall: Mitthögskolan , 2001Chapter in book (Other academic)
  • 16.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Omväxling. Dokumentation och utvärdering av MALM-projektet.2001In: Rapport 1: Första vårdprojektet., Sundsvall: Mitthögskolan , 2001Chapter in book (Other academic)
  • 17.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Qnet: kvinnligt akademiskt kompetensnätverk : dokumentation och utvärdering av ett projekt2004Report (Other academic)
  • 18.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Revirpink och kortslutning: Bidrag till Sundsvall 42, Datamässa, 12-14 okt 2004, Sundsvall2004Conference paper (Other academic)
  • 19.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Skolan som bärare av kaos och ordning, turbulens och mening: bidrag till konferens, Framgångsvimmel för alla anställda vid Sundsvalls skolor, 3-4 nov, 20042004Conference paper (Other academic)
  • 20.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Upptäckter av gemensamheter i en öppningsprocess: Nordic Sociological Conference, The Net Work Society. Opportunity or Opression, 15-17 aug, 2002, Reykjavik, Island.2002Conference paper (Other academic)
  • 21.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Upptäckter av gemensamheter i en öppningsprocess.: Nordic Sociological Conference,15-17 augusti 2002, Reykjavik, Island. Tema: The Network Society, Opportunity or Oppression.2002Conference paper (Other academic)
  • 22.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Varning! Spaning pågår!: Bidrag till Sundsvall 42, Datamässa, 15-17 okt, 2002, Sundsvall.2002Conference paper (Other academic)
  • 23.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Varning! Spaning pågår!: Sundsvall 42, Datamässa 15-17 oktober 2002, Sundsvall2002Conference paper (Other academic)
  • 24.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Vårdvägen 2. Dokumentation och utvärdering av MALM-projektet.2002In: Rapport 3: Andra vårdprojektet. Januari 2002, Sundsvall: Mitthögskolan , 2002Chapter in book (Other academic)
  • 25.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Vårdvägen 3. Dokumentation och utvärdering av MALM-projektet.2002In: Rapport 4: Tredje vårdprojektet. Juni 2002, Sundsvall: Mitthögskolan , 2002Chapter in book (Other academic)
  • 26.
    Eriksson, Ingalill
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Vårdvägen 4. Dokumentation och utvärdering av MALM-projektet.2002In: Rapport 5: Fjärde vårdprojektet. December 2002, Sundsvall: Mitthögskolan , 2002Chapter in book (Other academic)
  • 27.
    Eriksson, Ingalill
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Johansson, Ingela
    Det goda arbetet: friskfaktorer i arbetslivet : dokumentation och utvärdering av ett projekt i Västernorrland 2001-2002 /2002Book (Other academic)
  • 28.
    Eriksson, Ingalill
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Lund, Anna
    Medarbetarsamtal och rehabilitering; en del av arbetsmiljöarbetet: undersökning av goda exempel2003Report (Other academic)
  • 29.
    Eriksson, Ingemar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    High speed imaging analysis of laser welding2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Laser welding is often considered a new and exotic manufacturing method even though it has been used in industrial applications for nearly fifty years. In the early years only a few special applications justified the high investment cost involved, but as the price of the laser sources has reduced, industrial interest in laser welding has increased. As different weld situations have appeared, involving new materials etc. there is an increasing need to understand the weld process on a fundamental level, especially for the newer, high power and high quality 1μm laser sources (Disk laser, Fiber laser). Laser welding sometimes involves production limitations that are caused by the process itself, not the laser source. Weld defects such as humping or severe spattering can make the weld quality unacceptable and more knowledge of the physics involved in defect generation is needed. In this thesis high speed imaging is used as a method of acquiring fundamental knowledge about laser welding. Modern digital high speed cameras in combination with powerful laser illumination provide a clear and detailed view of the actual weld process. The information in these high speed videos provides a possibility to see how the process behaves. Just as a slow motion goal camera helps the referees to rule accurately in an athletic event, the high speed cameras can help laser welding researchers to improve their fundamental understanding. This thesis is composed of seven publications in scientific journals which are thematically linked by their focus on high speed imaging analysis of laser welding. In two shorter letters, new measurement methods are presented. In the first case a streak image method is utilized to measure the fluid flow velocity on the keyhole front, and in the second a pulsed digital holography method was employed to measure deformation during laser spot welding. The streak image method is further developed in two subsequent papers to confirm and quantify the downward flow on the keyhole front during high speed welding. In the three additional papers both new and previously known laser welding phenomena are analyzed by high speed imaging. The first of these papers discusses the correlation between the size of the vapor plume above the keyhole and the signal acquired by a commercial “laser weld monitoring” system. The next paper gives practical guidelines on how to choose parameters in a laser hybrid welding system, and the final paper discusses conditions under which surface tension effects can produce a self-sustaining hole in the melt pool that might produce defects in the weld.

  • 30.
    Eriksson, Ingemar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Laser welding in slow motion2011In: LIA Today, Vol. 19, no 2, p. 12-Article in journal (Other academic)
  • 31.
    Eriksson, Ingemar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Optical monitoring and analysis of laser welding2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    After the laser was invented in 1960, it was not long until someone started using this powerful source of light to weld parts together. Laser welding became an industrial application during the 1970's and the field has developed ever since. In 2008 a new 15kW fibre laser was installed at Luleå University of Technology, and at the same time a considerable investment was made in new digital high speed cameras. This combination of equipment enabled research on a new level, and a first step towards a more general understanding of laser welding.This thesis presents the results acquired by analyzing high speed videos of laser welding.Qualitative and quantitative results from these high speed videos have revealed a considerable amount of information about the physics which underlies the laser welding process, including direct measurements of fluid flow within the melt pool and the interpretation of electromagnetic signals which emanate from the welding process.The thesis comprises three papers which are thematically linked by their concentration on the analysis of high speed imaging of the laser welding process.Paper A concerns the quantitative evaluation of high speed imaging of the time-dependent metal vapour jet that streams out of the laser welding vapour capillary. This work has revealed an important correlation. The output of commercially available process monitoring photodiodes (used for detecting infrared radiation) correlates with the fluctuating vapour jet above the weld, instead of, as was previously assumed, with the radiation from the molten and solid surface.In paper B, for the first time, ultra-high speed images of the surface of the laser welding vapour capillary have been obtained, (at a rate of 180 000 frames per second) with good spatial resolution and contrast. In addition, a streak technique was developed that measures and the time-dependent melt flow velocity along a selected line. Wave-like patterns that flow down the capillary have been directly observed. These phenomena are of essential importance for a basic understanding of the laser welding process and are a very powerful support for future research, e.g. for modelling and simulation.Using the above method, the velocity of the flowing vapour capillary waves was quantitatively evaluated in Paper C for varying process parameters, like laser power, focus position or welding speed, revealing clear, important trends of the laser welding process.

  • 32.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    New high-speed photography technique for observation of fluid flow in laser welding2010In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 49, no 10Article in journal (Refereed)
    Abstract [en]

    Recent developments in digital high-speed photography allow us to directly observe the surface topology and flow conditions of the melt surface inside a laser evaporated capillary. Such capillaries (known as keyholes) are a central feature of deep penetration laser welding. For the first time, it can be confirmed that the liquid capillary surface has a rippled, complex topology, indicative of subsurface turbulent flow. Manipulation of the raw data also provides quantitative measurements of the vertical fluid flow from the top to the bottom of the keyhole.

  • 33.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Haglund, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Holographic measurement of thermal distortion during laser spot welding2012In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 51, no 3Article in journal (Refereed)
    Abstract [en]

    Welding distortion is an important engineering topic for simulation and modeling, and there is a need for experimental verification of such models by experimental studies. High-speed pulsed digital holography is proposed as a measurement technique for out-of-plane welding distortion. To demonstrate the capability of this technique, measurements from a laser spot weld are presented. A complete twodimensional deformation map with submicrometer accuracy was acquired at a rate of 1000 measurements per second. From this map, particular points of interest can be extracted for analysis of the temporal development of the final distortion geometry.

  • 34. Eriksson, Ingemar
    et al.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Evaluation of laser weld monitoring: a case study2009In: Congress proceedings: ICALEO, 28th International Congress on Applications of Lasers & Electro-Optics : November 2 - 5, 2009 - Orlando, FL : Laser Materials Processing Conference, Laser Microprocessing Conference, Nanomanufacturing Conference, poster presentation, gallery, Orlando, Fla: Laser institute of America , 2009, Vol. 102, p. 1419-1425Conference paper (Refereed)
    Abstract [en]

    On-line monitoring of the quality of laser welding is of interest for many industrial applications. For photodiodes the monitoring strategy usually aims at observing whether the signal exceeds a threshold. This well known technique is mainly based on empirical values, thus the monitoring has to be trained for each application. For improved understanding of the context between the physics of a welding defect generated and the resulting voltage signal, the experiments were observed by high speed imaging, followed by evaluation and modelling. A commercial system with three detector wavelength windows was studied for nine different industrial welding applications with distinct defects. We here present selected cases for which we try to generalise the findings and to draw conclusions for the applicability of commercial monitoring systems. For example humping was clearly detected by the signal, spatter and crater formation for overlapping Zn-coated steel surprisingly not. An interesting cause for welding defects is contamination of the joint prior to welding by oil, grease or detergents. The corresponding experiments showed unexpected signal responses, which can be partially explained by the analysis. We summarise that improved understanding of the signal causes facilitates to apply monitoring systems in a reliable manner.

  • 35.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Melt behavior on the keyhole front during high speed laser welding2013In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 51, no 6, p. 735-740Article in journal (Refereed)
    Abstract [en]

    The flow of molten metal on the front wall of a laser generated welding keyhole has been observed by high speed photography, optically measured by mapping the flow of ripples on the liquid surface and theoretically calculated. A clear downward flow can be observed and measured by a Particle Image Velocimetry algorithm. A theoretical calculation of the melt thickness on the keyhole front is also presented. Results indicate that the thickness of the liquid on the keyhole front is similar to that of the resolidified layer found in micrographs of the front if the laser is suddenly turned off. The measured surface ripple flow speeds are between two and four times as high as the theoretical average fluid flow rate.

  • 36. Eriksson, Ingemar
    et al.
    Norman, Peter
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Basic study of photodiode signals from laser welding emissions2009In: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference ; 24th - 26th August 2009 in Copenhagen, Kgs. Lyngby: ATV-SEMAPP , 2009Conference paper (Refereed)
    Abstract [en]

    Photodiodes are commonly used to monitor laser welding as a cheap, rugged, online method to get an indication of changes in the process, particularly the occurrence of defects. However, the correlations between the signal characteristics and the process are usually empirical and not fully understood. In this basic study we try to obtain a better understanding of the generation of the signals from the laser welding process. By synchronising high speed imaging with photodiode signals in three wavelength spectra, we attempt to identify the contributions from different geometrical domains and temporal events, particularly from the weld pool surface, the keyhole opening and the escaping metal vapour flow. It is particularly valuable to study dynamic behaviour during pulsed laser welding. A quantitative estimation is difficult, but , with the help of high speed photography and modelling, clear correlations between different dynamic events and signal changes can be identified.

  • 37.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Guidelines in the choice of parameters for hybrid laser arc welding with fiber lasers2013In: Physics Procedia, ISSN 1875-3892, E-ISSN 1875-3892, Vol. 41, p. 119-127Article in journal (Refereed)
    Abstract [en]

    Laser arc hybrid welding has been a promising technology for three decades and laser welding in combination with gas metal arc welding (GMAW) has shown that it is an extremely promising technique. On the other hand the process is often considered complicated and difficult to set up correctly. An important factor in setting up the hybrid welding process is an understanding of the GMAW process. It is especially important to understand how the wire feed rate and the arc voltage (the two main parameters) affect the process. In this paper the authors show that laser hybrid welding with a 1 μm laser is similar to ordinary GMAW, and several guidelines are therefore inherited by the laser hybrid process.

  • 38.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    High speed video analysis of melt flow inside fiber laser welding keyholes2011In: Congress proceedings ICALEO: 30th International Congress on Applications of Lasers & Electro-Optics : October 23-27, 2011, Orlando, Fl., Laser institute of America , 2011, p. 221-226Conference paper (Refereed)
    Abstract [en]

    A high speed video survey of melt flow within fiber laser welding keyholes has revealed a number of interesting observations about the mechanics of weld formation. Using Streak Images and FFT (Fast Fourier Transform) techniques to interpret the video results, quantitative values of fluid flow velocities down the keyhole front have been established. The results have lead to a phenomenological understanding of some of the quality problems which arise at high welding speeds -such as undercut and humping.

  • 39.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Measurements of fluid flow on keyhole front during laser welding2011In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 16, no 7, p. 636-641Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of a high speed video survey of melt flow on the front face of a keyhole created during fibre laser welding. Using fast Fourier transform techniques, quantitative values of fluid flow velocities down the keyhole front have been established. The results have led to a phenomenological understanding of some of the quality problems which arise at excess welding speeds. The downward flow velocity on the keyhole front is found to be generally independent of welding speed, and proportional to laser power

  • 40.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Melt flow measurement inside the keyhole during laser welding2011In: 13th NOLAMP Conference: 13th Conference on Laser Materials Proce Nordic Countries 27 - 29 June 2011 / [ed] Einar Halmøy, Trondheim: Department of Geography, Norwegian University of Science and Technology, 2011Conference paper (Refereed)
    Abstract [en]

    Laser keyhole welding has been in use for decades, but many of the complex mechanisms which take place within the keyhole remain poorly understood. Thispaper describes a streak image technique based on videos from high speed digital cameras. Itis similar to the technique used in goal cameras to visualize time-dependent events. Thecamera’s ability to acquire high speed image patterns with clear grayscale contrast hasenabled us to see the melt flow on the keyhole surface. In this paper the measured flowvelocity down the front of the keyhole is presented, showing a clear vertical downwardmotion on the keyhole front with speeds of the order of meters per second.

  • 41.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Kaplan, Alexander
    Signal overlap in the monitoring of laser welding2010In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 21, no 10Article in journal (Refereed)
    Abstract [en]

    Laser weld monitoring is usually based on the feedback from three photodiodes which are intended to provide independent information about the thermal condition of the melt (the T signal), the radiation from the plume of a heated gas above the melt (the P signal) and the amount of reflected laser light (the R signal). This work demonstrates that, in fact, the plume of the hot gas above the weld pool contributes a large part of the thermal signal, which has hitherto been assumed to come only from the melt itself. It is suggested that the correlation between the T and P signals is so strong that a T-P signal would be more useful than the raw T signal in identifying the fluctuations in infrared radiation from the melt pool

  • 42.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Surface tension generated defects in full penetration laser keyhole welding2014In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 26, no 1, article id 12006Article in journal (Refereed)
    Abstract [en]

    During laser keyhole welding of thin plates the melt pool is relatively wide compared to the plate thickness. Under certain conditions an elongated keyhole can be created and a permanent hole is sometimes left in the weld seam. The generation of such holes is determined by surface tension effects in the melt which can generate a self sustaining geometry at the rear of the melt pool. The geometry of the shape is known as a catenoid and has clear geometrical limits.

  • 43.
    Eriksson, Ingemar
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Kaplan, Alexander
    Ultra high speed camera investigations of laser beam welding2010In: Congress proceedings ICALEO: 29th International Congress on Applications of Lasers & Electro-Optics : September 26 - 30, 2010, Anaheim, CA, USA, Anaheim Marriot ; [including] Laser Materials Processing Conference, Laser Microprocessing Conference, Nanomanufacturing Conference / [ed] Xinbing Liu, Anaheim, CA: Laser institute of America , 2010, p. 172-178Conference paper (Other academic)
    Abstract [en]

    With the help of high speed camera equipment, researchers can now directly observe melt flow phenomena which only could be imagined or simulated in the past. In this paper the motion of the molten metal inside the keyhole has been observed at frame rates as high as 180000 fps to provide useful information about the laser beam welding process. This paper describes two different cases where high speed imaging has given new insights into the laser beam welding process: A. In pulsed welding the melt pool oscillations can create ripples on the solidified weld surface. With the help of a high speed camera this phenomenon was analyzed, and the pulse shape was adjusted to reduce the ripple amplitude to a minimum. B. In Zn-coated steel edge welding it could be seen that blowouts were sometimes created in the melt pool at some distance behind the keyhole. Direct slowmotion observation has led to the formulation of a phenomenological model of this effect.

  • 44.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Analysing vocational knowing with help of learning studies2014In: Book of Abstracts, 2014, p. 26-26Conference paper (Refereed)
    Abstract [en]

    The issue of this presentation is to discuss how learning study can function as a tool for expanding a didactical understanding of theoretical and practical aspects of knowing. By tradition much vocational knowing is described and perceived in dichotomised terms as practical or theoretical. Taking an activity theoretical perspective (CHAT) this type of dichotomies is problematic since knowledge is seen as developed and used in a specific activity or practice. Thus, knowing must be regarded as complex, multi facetted (multi-voiced) and situational where, theoretical aspects are built into artefacts as professional language, models, and of course physical tools ect. Knowing how to use, value and assess (and develop) the practice-specific artefacts is demanding both a “theoretical” and “practical” knowing. In this presentation this issues will be discussed in relation to an example from a learning study in home economics where students knowing of how to prepare a cold emulsion (exemplified as mayonnaise) where focused.

    Learning study is a teacher led model developed to improve teaching practices in a way that enhances students learning. The model is interventionist– aiming to develop teaching and it is iterative – consisting of repeated analysis, design, evaluation and revisions of a lesson. Further, the model has a special focus on how the content is treated by teachers and students in the on-going classroom interactions, how tools are used and what subject specific content is made available for the students. The core of a learning study is the so-called ‘object of learning’ (OL). The object of learning needs to be identified and analysed both in relation to the historically and culturally developed knowing (in this case cold emulsions) and students’ actual understanding of the targeted knowledge. This identification and analysis is led by questions as: what in the targeted knowing is difficult for the students to understand and master? What do students understand and perhaps misunderstand? What knowing is built into the tools and rules? What do a knowledgeable person master and how?

    If the research and development is focusing the meaning of knowing and the relation between practical and theoretical aspects of knowing the identification and analysis of an OL can help teachers and researchers to develop subject specific didactical knowledge. In order to understand the knowing embedded in i.e. making a cold emulsion the students simultaneously need to master both the manual tools as well as the theoretical principles of a cold emulsion.

  • 45.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Constitution of Objects in DWR Activity2015In: Contemporary Approaches to Activity Theory.: Interdisciplinary Perspectives on Human Behavior / [ed] Hansson, Thomas, Hershey, PA: IGI Global, 2015Chapter in book (Refereed)
    Abstract [en]

    A shared research object between teachers and researchers in Developmental Work Research (DWR) aims at development of teaching practices and forming of subject-specific knowledge. Currently, design experiments, action research, and formative interventions are used in educational research. A multitude of approaches show an overarching interest in developing teaching and learning practices. Action research and formative interventions include and empower teachers. However, in many DWR projects, teachers and researchers have different objects. In a tradition where teachers are regarded as learners, a shared research object is of interest. This chapter problematizes the relationship between teachers and researchers with the help of three DWR projects. It is challenging to establish a DWR project in which teachers and researchers aim at realising the same object. However, when this is a case, such projects may contribute to new knowledge that enhances student learning and educational, clinical, and subject-matter research.

  • 46.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Cultural tools as didactical tool in planning for a learning activity2015Conference paper (Other academic)
    Abstract [en]

    In this paper I want to address issues related the possibility to use culturally developed tools as a mean to design potential learning tasks in evolving learning activities that can enhance vocational specific ways of mathematical knowing.

    The concept of learning activity is often discussed in relation to the mathematical programme developed by Davydov and his colleagues (Davydov, 2008). Within a curricular program, such as that of Davydov, discussions concerning learning activity are likely to appear rather as a general educational model than as a subject specific intermediate theory to be used to by teachers to design different teaching situations referring to relevant vocational practices. In Sweden national curriculum (on all levels) is formed in a way that requires teachers to design their teaching so that students can develop different subject/vocational specific competences. Learning activity, with its focus on students’ agency and theoretical development seems to be a powerful didactical tool but there is little to support teachers in how to analyse and develop curriculum content and from that analysis design learning tasks (around which a learning activity can develop). Anna Stetsenko an d Igor Arievitch, with references to Vygotsky and Gal’perin, open up for such a pathway in their discussion on how analysis of specific cultural tools in terms of their cultural and historical development and practical use can function as a starting point in the design of such learning tasks.

    What are the possibilities to design content rich learning tasks based on analysis of which mathematical tools are used in different vocational practices? What similarities and differences can be found in how mathematical tools are used in those vocational practices? What specific ways of knowing are embedded in the mastery of those tools?

  • 47.
    Eriksson, Inger
    Stockholm University, Faculty of Humanities, Department of Humanities and Social Sciences Education.
    Delad kompetens i gymnasiesärskolans berättelseskrivande – ett sociokulturellt perspektiv på lärande och utveckling2017Other (Other academic)
    Abstract [sv]

    Den här artikeln syftar till att kunna fungera som ett diskussionsunderlag för lärare i arbetet med att utveckla elevers förmåga till berättelseskrivande. Utifrån ett sociokulturellt perspektiv och framför allt Vygotskijs arbete presenteras och diskuteras några möjliga konsekvenser för hur undervisning kan organiseras, i syfte att optimera elevernas lärande. Vygotskij (1963, 2001) beskriver individers lärande som i första hand en fråga om att få tillgång till kulturellt utvecklade kunskaper.

  • 48.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Designing teaching-learning practices with activity theory as a guiding tool: examples from a teacher-researcher DWR-project2013In: A Nordic perspectiveon the Cultural and the Activity approach in Theory and Practice / [ed] Hans Knutagård, Britt Krantz och Marie Jedemark (editors), 2013, p. 29-36Conference paper (Other academic)
  • 49.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Didactic Science and Early Childhood Education.
    Innehållet i fokus - kemiundervisning i finlandssvenska klassrum2010Collection (editor) (Other academic)
    Abstract [sv]

    I flera jämförande internationella studier hamnar de finska eleverna i toppen. I denna forskningsrapport studeras kemiundervisningen i finlandssvenska klassrum utifrån bl.a. klassrumsobservationer. Rapporten består av sex kapitel där författarna bl.a. tar upp följande frågor: Vad kännetecknar undervisningspraktiken i en finlandssvensk klass? Vilka texter används i klassrummet? Vad betraktas som viktig respektive mindre viktig kunskap? I ett av kapitlen analyseras vilka frågor läraren ställer till eleverna och vilken feedback som ges. I studien ingick fyra lärare, och i det avslutande kapitlet analyseras deras provkonstruktion och bedömningsarbete. Texterna vänder sig till alla som är intresserade av bedömningsfrågor, kunskapsfrågor, lärande och undervisning. Forskningsprojektet är finansierat av Vetenskapsrådet.

  • 50.
    Eriksson, Inger
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Kemiundervisning, text och textbruk i finlandssvenska och svenska skolor: en komparativ tvärvetenskaplig studie2011Collection (editor) (Refereed)
    Abstract [sv]

    Vilka kemikunskaper prioriteras i svenska och finlandssvenska klassrum? Vilka kulturella skillnader i undervisningen kan utläsas? I denna forskningsrapport presenteras de huvudsakliga resultaten från forskningsprojektet Kemitexter som redskap för naturvetenskapligt lärande –en komparativ studie av undervisningspraktiker i svenska och finlandssvenska klassrum. Studien har bland annat tillkommit till följd av att finska elevers resultat är bland de främsta i flera jämförande internationella studier. Rapporten består av sju kapitel som alla på olika sätt analyserar videobandade klassrumsobservationer, intervjuer och texter från tre svenska och fyra finlandssvenska klassrum. De olika analyserna som presenteras i denna rapport avser att ge mångsidiga beskrivningar av hur ett specifikt naturvetenskapligt innehålltar form i undervisningen. Sammantaget ger texterna ett underlag för en fördjupad diskussion om vad som utgör skillnader och likheter i undervisningen i de två länderna. Texterna vänder sig till alla som är intresserade av frågor om undervisning, textbruk, kunskap, lärande och bedömning, med speciellt fokus på kemi. Forskningsprojektet har finansierats av Vetenskapsrådet.

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