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  • 151.
    Cervin, Ida
    et al.
    Sectra AB, Chalmers University of Technology, Sectra AB, Gothenburg, Sweden.
    Molin, Jesper
    Center for Medical Image Science and Visualization, Chalmers University of Technology, Sectra AB, Gothenburg, Sweden.
    Lundström, Claes
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Improving the creation and reporting of structured findings during digital pathology review2016Inngår i: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 7, nr 1, s. 32-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Today, pathology reporting consists of many separate tasks, carried out by multiple people. Common tasks include dictation during case review, transcription, verification of the transcription, report distribution, and report the key findings to follow-up registries. Introduction of digital workstations makes it possible to remove some of these tasks and simplify others. This study describes the work presented at the Nordic Symposium on Digital Pathology 2015, in Linköping, Sweden. Methods: We explored the possibility to have a digital tool that simplifies image review by assisting note-taking, and with minimal extra effort, populates a structured report. Thus, our prototype sees reporting as an activity interleaved with image review rather than a separate final step. We created an interface to collect, sort, and display findings for the most common reporting needs, such as tumor size, grading, and scoring. Results: The interface was designed to reduce the need to retain partial findings in the head or on paper, while at the same time be structured enough to support automatic extraction of key findings for follow-up registry reporting. The final prototype was evaluated with two pathologists, diagnosing complicated partial mastectomy cases. The pathologists experienced that the prototype aided them during the review and that it created a better overall workflow. Conclusions: These results show that it is feasible to simplify the reporting tasks in a way that is not distracting, while at the same time being able to automatically extract the key findings. This simplification is possible due to the realization that the structured format needed for automatic extraction of data can be used to offload the pathologists' working memory during the diagnostic review.

    Fulltekst (pdf)
    fulltext
  • 152.
    Chen, Min
    et al.
    University of Oxford, England.
    Ebert, David
    Purdue University, IN 47907 USA.
    Hauser, Helwig
    University of Bergen, Norway.
    Heer, Jeffrey
    University of Washington, WA 98195 USA.
    North, Chris
    Virginia Polytech Institute and State University, VA 24061 USA.
    Qu, Huamin
    Hong Kong University of Science and Technology, Peoples R China.
    Suien, Han-Wei
    Ohio State University, OH 43210 USA.
    Tory, Melanie
    University of Victoria, Canada.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    IEEE VISUAL ANALYTICS SCIENCE & TECHNOLOGY CONFERENCE, IEEE INFORMATION VISUALIZATION CONFERENCE, AND IEEE SCIENTIFIC VISUALIZATION CONFERENCE2014Inngår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 20, nr 12, s. XI-XIVArtikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 153.
    Chow, Joyce A
    et al.
    RISE Interactive Institute, Norrköping, Sweden.
    Törnros, Martin E
    Interaktiva Rum Sverige, Gothenburg, Sweden.
    Waltersson, Marie
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Richard, Helen
    Region Östergötland, Diagnostikcentrum, Klinisk patologi.
    Kusoffsky, Madeleine
    RISE Interactive Institute, Norrköping, Sweden.
    Lundström, Claes
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Sectra AB, Linköping, Sweden.
    Kurti, Arianit
    RISE Interactive Institute, Norrköping, Sweden.
    A Design Study Investigating Augmented Reality and Photograph Annotation in a Digitalized Grossing Workstation2017Inngår i: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 8, nr 31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context: Within digital pathology, digitalization of the grossing procedure has been relatively underexplored in comparison to digitalization of pathology slides. 

    Aims: Our investigation focuses on the interaction design of an augmented reality gross pathology workstation and refining the interface so that information and visualizations are easily recorded and displayed in a thoughtful view. 

    Settings and Design: The work in this project occurred in two phases: the first phase focused on implementation of an augmented reality grossing workstation prototype while the second phase focused on the implementation of an incremental prototype in parallel with a deeper design study. 

    Subjects and Methods: Our research institute focused on an experimental and “designerly” approach to create a digital gross pathology prototype as opposed to focusing on developing a system for immediate clinical deployment. 

    Statistical Analysis Used: Evaluation has not been limited to user tests and interviews, but rather key insights were uncovered through design methods such as “rapid ethnography” and “conversation with materials”. 

    Results: We developed an augmented reality enhanced digital grossing station prototype to assist pathology technicians in capturing data during examination. The prototype uses a magnetically tracked scalpel to annotate planned cuts and dimensions onto photographs taken of the work surface. This article focuses on the use of qualitative design methods to evaluate and refine the prototype. Our aims were to build on the strengths of the prototype's technology, improve the ergonomics of the digital/physical workstation by considering numerous alternative design directions, and to consider the effects of digitalization on personnel and the pathology diagnostics information flow from a wider perspective. A proposed interface design allows the pathology technician to place images in relation to its orientation, annotate directly on the image, and create linked information. 

    Conclusions: The augmented reality magnetically tracked scalpel reduces tool switching though limitations in today's augmented reality technology fall short of creating an ideal immersive workflow by requiring the use of a monitor. While this technology catches up, we recommend focusing efforts on enabling the easy creation of layered, complex reports, linking, and viewing information across systems. Reflecting upon our results, we argue for digitalization to focus not only on how to record increasing amounts of data but also how these data can be accessed in a more thoughtful way that draws upon the expertise and creativity of pathology professionals using the systems.

    Fulltekst (pdf)
    fulltext
  • 154.
    Chung, Michelle
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Hansson, Victoria
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    The use of layoutprinciples for the creation of a uniform visual communication for printed marketing material2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Ett inkonsekvent användande av den visuella kommunikationen kan leda till förvirring hos mottagaren och ge negativa associationer för företaget. För att undvika förvirring är det viktigt med tydliga riktlinjer för hur ett företags visuella kommunikation ska förmedlas till mottagaren. Syftet med denna fallstudie var därför att undersöka vilka layoutprinciper som är nödvändiga för att skapa en enhetlig visuell kommunikation för tryckt marknadsföringsmaterial. Vidare undersöktes även hur dessa aspekter bör användas i layoutarbetet av tryckt marknadsföringsmaterial. Fallet som studien utgick ifrån var Fiskexporten, ett livsmedelsföretag i Varberg. För att svara på syftet delades studien in i två faser, designfas 1 respektive designfas 2. Eftersom studien hade två designfaser användes en explanantory sequential mixed method design. Studien visade de layoutprinciper som finns till hands för designarbetet av visuell kommunikation kan delas in i rörliga- och fasta layoutprinciper. De rörliga layoutpricniperna kan, beroende på hur de används skapa en mer eller mindre enhetlig visuell kommunikation. De fasta layoutprinciperna är däremot nödvändiga och grundläggande för effektiv och enhetlig visuell kommunikation. Det slutgiltiga resultaten av studien var att ett konsekvent användande av både rörliga- och fasta layoutprinciper ger intrycket av enhetlighet mellan olika marknadsföringsmaterial.

    Fulltekst (pdf)
    fulltext
  • 155.
    Cleveson, Aron
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Sheet piling for permanent application in solid water hazards for construction of fishways.2014Independent thesis Basic level (university diploma), 20 poäng / 30 hpOppgave
    Abstract [en]

    När ett vattendrag regleras genom byggnation av dammar och vattenkraftverk skapas hinder, även så kallade vandringshinder för fiskar och andra vattenlevande organismer. Genom att bygga en fiskväg möjliggörs åter denna vandring. På senare år har det blivit vanligt att anlägga fiskvägar på ett naturligt sätt. Den senast framtagna metoden för att anlägga naturliga fiskvägar är att bygga ett så kallat inlöp. Inlöpet uppförs genom att en del av en damm skiljs av med hjälp av en skiljevägg som ansluts mot befintlig dammkonstruktion. Skiljeväggen kan utföras på flera sätt, ett av dess är genom att driva ner en kontinuerlig stålspont. Syftet med examensarbetet är att undersöka möjligheten att uppföra ett inlöp med hjälp av en tät kontinuerlig konsolspont av stål, i anslutning till befintlig dammkonstruktion. Målet med examensarbetet är att öka kunskapen vid användning av kontinuerlig stålspont för byggnation av fiskvägar i anslutning till befintliga dammkonstruktioner.

    Fulltekst (pdf)
    fulltext
  • 156.
    Cooper, Matthew
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Fridlund, Alexander
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Andel, Miroslav
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Bojan, Claudiu
    Eurocontrol, Luxembourg.
    Hardy, Jean-Luc
    Eurocontrol Experimental Centre, Brétigny.
    Educational Benefits of 3D Displays in Early Controller Training2010Inngår i: Proceedings of the 27th International Congress of the Aeronautical Sciences (ICAS2010) / [ed] Professor Ian Grant, 2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    There have been many attempts to exploit three- dimensional displays in Air Traffic Control where it has long been suspected that the 3D display may help to reduce the cognitive load on the controller by removing the need to construct an elaborate mental model of the air space and the traffic contained within it. 3D displays could allow the controller to simply re-interpret the presented information in real time without the need for them to construct this internal model and without the need to remember large amounts of complex information. This should result in controllers being able to manage larger numbers of aircraft without loss of safety, as well as reducing the pressure on controllers allowing for longer work sessions with less problems of mental fatigue.

    The purpose of this study has been to explore the use of 3D in controller training and, in this initial study, to examine the basic reaction of the controllers to 3D representations and the effects, if any, which the introduction of 3D has on their work.

  • 157.
    Corell, Simon
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    A Recurrent Neural Network For Battery Capacity Estimations In Electrical Vehicles2019Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This study is an investigation if a recurrent long short-term memory (LSTM) based neural network can be used to estimate the battery capacity in electrical cars. There is an enormous interest in finding the underlying reasons why and how Lithium-ion batteries ages and this study is a part of this broader question. The research questions that have been answered are how well a LSTM model estimates the battery capacity, how the LSTM model is performing compared to a linear model and what parameters that are important when estimating the capacity. There have been other studies covering similar topics but only a few that has been performed on a real data set from real cars driving. With a data science approach, it was discovered that the LSTM model indeed is a powerful model to use for estimation the capacity. It had better accuracy than a linear regression model, but the linear regression model still gave good results. The parameters that implied to be important when estimating the capacity were logically related to the properties of a Lithium-ion battery.En studie över hur väl ett återkommande neuralt nätverk kan estimera kapaciteten hos Litium-ion batteri hos elektroniska fordon, när en en datavetenskaplig strategi har använts.

    Fulltekst (pdf)
    A Recurrent Neural Network For Battery Capacity Estimations In Electrical Vehicles
  • 158.
    Corin, Filippa
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Österling, Lovisa
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    To transfer a magazine’s visual identity – Hemmets Journal from printed version to iPad version, for older readers2015Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [en]

    I denna studie undersöks nya interaktiva möjligheter för veckotidningen Hemmets Journal på plattformen iPad, genom en analys av Hemmets Journals visuella identitet, inför en identitetsöverföring från tryckt till digital plattform. Arbetet mynnade ut i en interaktiv prototypdesign, på en mer avancerad upplevelse- och användaranpassad nivå än Hemmets Journals befintliga och mindre användarvänliga digitala tidning. Prototypens användarvänlighet och designens igenkänningsbarhet för äldre teknikanvändare mättes genom testsessioner och kvalitativa intervjuer, med användare inom Hemmets Journals målgrupp.

    Fulltekst (pdf)
    fulltext
  • 159.
    Costantini, Stefania
    et al.
    Dip. di Informatica, Universit` a di L’Aquila, L’Aquila, Italy.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Pereira, Luis M
    Dept. de Inform ́ atica, Centro de Inteligˆ encia Artificial (CENTRIA), Universidade Nova de Lisboa, Caparica, Portugal.
    Conditional Learning of Rules and Plans by Knowledge Exchange in Logical Agents2011Inngår i: Rule-Based Reasoning, Programming, and Applications: 5th International Symposium, RuleML 2011 – Europe, Barcelona, Spain, July 19-21, 2011. Proceedings / [ed] N. Bassiliades, G. Governatori, and A. Pasckhe, Springer Berlin/Heidelberg, 2011, s. 250-265Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper is related to logical agents and in particular discusses issues related to learning sets of rules from other agents. In principle, the approach extends to agent societies a feature which is proper of human societies, i.e., the cultural transmission of abilities. However, the new knowledge cannot be blindly accepted and incorporated, but should instead be evaluated (and thus possibly discarded) according to its usefulness. We propose a technique and its formalization.

  • 160.
    Costantini, Stefania
    et al.
    Dept. of Computer Science, L'Aquila University, Italy.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Pereira, Luis M
    Dept. of Computer Science, Universidade Nova de Lisboa, Lisbon.
    Tocchio, Arianna
    Dept. of Computer Science, L'Aquila University, Italy.
    Ensuring Agent Properties under Arbitrary Sequences of Incoming Events2010Inngår i: Experimental evaluation of algorithms for solving problems with combinatorial explosion / [ed] Marco Gavanelli and Toni Mancini, Bologna: CEUR , 2010Konferansepaper (Fagfellevurdert)
  • 161.
    Costantini, Stefania
    et al.
    Dept. of Computer Science, L'Aquila University.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Pereira, Luis M
    Dept. of Computer Science, Universidade Nova de Lisboa, Lisbon.
    Toni, Francesca
    Department of Computing, Imperial College, UK.
    Learning and Evolving Agents in User Monitoring and Training2010Inngår i: Procs. Congresso Nazionale, Associazione Italiana per l’Informatica ed il Calcolo Automatico / [ed] Paola Inverardi, 2010Konferansepaper (Fagfellevurdert)
  • 162.
    Costantini, Stefania
    et al.
    University of L'Aquila, Italy.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Pereira, Luis M
    New University of Lisbon, Portugal.
    Toni, Francesca
    Department of Computing, Imperial College London.
    Meta-axioms and Complex Preferences in Evolving Logical Agents2011Inngår i: / [ed] L. Antunes, H. S. Pinto, R. Prada and P. Trigo, Springer, 2011, s. 580-594Konferansepaper (Fagfellevurdert)
  • 163.
    Crafoord, Carina
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Wik, Emma
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Hur ett varumärke kan förmedla sina kärnvärden och en unisex-känsla i ett intresseväckande Instagramflöde2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Syftet med studien är att ta reda på hur ett företag bör utforma sina Instagrambilder för att uppfattas enligt företagets kärnvärden och förmedla en unisex-känsla för att skapa ett attraktivt Instagramflöde. Studien görs på uppdrag av The Shocelace Brand Stockholm och resultatet ska fungera som ett underlag för företagets kommande Instagraminlägg. Uppsatsen grundar sig i teorier om varumärken, positionering, genus, färg, sociala medier, reklambilder och semiotik. Information för studien har vidare samlats in genom kvalitativa intervjuer med respondenter från målgruppen, företagsledningen och en yrkesverksam fotograf. I analysen utreds respondenternas tankar och preferenser för att identifiera samband. Studien påvisar att ett enhetligt, tilltalande och intresseväckande Intagramflöde skapas genom att använda sig av professionella genomarbetade bilder som är redigerade med en återkommande färg eller färgton. Flödet bör innehålla en variation av produktbilder och personer för att vara intresseväckande. För att tilltala båda könen krävs en variation av bilder vilka upplevs som manliga, kvinnliga och unisex. Dessa bilder skapas genom att tänka igenom poseringen, element och själva könet samt beteendet hos personen i bilden. För att ett Instagraminlägg ska återspegla ett företags värdeord bör det finnas ett samspel mellan bildens kontext samt element. Förslag till vidare forskning är att utvärdera underlaget, intervjua flera personer kring kärnvärdena samt studera hur genus skildras i sociala medier.

    Fulltekst (pdf)
    Hur ett varumärke kan förmedla sina kärnvärden och en unisex-känsla i ett intresseväckande Instagramflöde
  • 164.
    Dahlin, Jesper
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Simon
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Streamline the production process using Lean 5S2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Då byggbranschen idag står inför stora förändringar bör arbetsplatserna bli mer effektiva. Rörelse och väntan är två stora slöserier som kostar mycket pengar för företagen. Denna rapport ska undersöka hur produktionsprocessen kan effektiviseras med hjälp av Leanverktyget 5S. Bakgrunden till problemet är tidsförluster i produktionen där företagen lägger mycket tid på onödiga slöserier såsom väntan och materialhantering.

    Arbetet har utförts tillsammans med NCC Constructionen där tre byggarbetsplatser i Norrköpings region har studerats. De frågor som skulle besvaras var:

    • Var ligger de största slöserierna när 5S inte används?
    • Hur påverkas slöserierna när 5S används?
    • Hur kan arbetsmetoden 5S förbättras inför kommande byggen?

    Resultatet som kommit fram efter studien var att rörelse och väntan är de största slöserierna när 5S inte används. Vad som kunde ses på arbetsplatsen som bedrev arbete med 5S var att väntan minskade dock var rörelsen fortfarande kvar men avsevärt reducerad. Det som tydligt kan förbättras inför kommande byggen är en kombination av att utbilda yrkesarbetarna i vad 5S handlar om och hur engagemanget kan öka för att få en så effektiv arbetsplats som möjligt.

    Fulltekst (pdf)
    fulltext
  • 165.
    Dahlman, Pierre
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Design av grafiskt tryck för ökad jämlikhet inom skateboard - utformning av grafiskt tryck för att främka kvinnliga skateboardåkare2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Studien undersöker och utformar ett grafiskt tryck för att främja kvinnliga skateboardåkare.Kvinnor inom skateboard har länge varit i minoritet och de har inte samma utbud när det kommer till varumärken. En bidragande orsak är de fördomar som finns om kvinnliga skateboardåkare. En pilotstudie genomfördes för att undersöka dagens varumärken och vilka preferenser som finns. Inom ramen för studien gjordes även en förstudie för att undersöka vilka kategorier inom deck-art som tilltalar målgruppen. Studiens designprocess använde sig av de teorier och åsikter som framkommit, och syftade till att utforma designalternativ som motsvarade dessa. Resultatet blev att två starka koncept togs fram. Efter en värderingsprocess i form av en kvantitativ enkät, med 19 respondenter, samt kvalitativa intervjuer med två aktiva, kunde en slutgiltig design skapas. Studien visar att den design som tagits fram är lämplig för både skateboard och t-shirt, och var omtyckt av målgruppen.

    Fulltekst (pdf)
    Design av grafiskt tryck för ökad jämlikhet inom skateboard - utformning av grafiskt tryck för att främka kvinnliga skateboardåkare
  • 166.
    Danielsson, Melinda
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Bild som ett första intryck - Hur stiliserade bilder på framsidan av en broschyr kan utformas för att reflektera och förmedla budskapet2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Det tillkommer ständigt nya medlemmar till idrottsföreningar. Det finns idag en avsaknad av en tydlig information kring hur en svensk lagidrottsförening fungerar och det ökar behovet av en informativ broschyr. Den här studien syftar till att undersöka hur stiliserade bilder på en framsida av en informerande broschyr kan utformas för att reflektera svensk lagidrott. För att besvara syftet skapades tre olika typer av inriktningar och två bilder i vardera inriktning. Studien visade att alla bilder kan kopplas till lagidrott när betraktaren känner till kontexten. Tydlighet, enkelhet, estetik samt vad och hur mycket bilden beskriver, är alla faktorer som påverkar respondenternas uppfattning. Människosilhuetter som klatschar händerna mot varandra är mest omtyckt och genererar flest kopplingar till idrott. Bilden baseras på ord som framgång, gemenskap, glädje och laganda och dessa beskrivningar relaterar till det önskvärda budskapet i kommunikationen. Studien visar att en bild är lättast att läsa av då elementen samspelar och skapar en helhet som betraktaren kan relatera till. Många faktorer påverkar dock om en bild upplevs lätt att läsa av. Det går därför inte att med säkerhet säga att någon av bilderna är lättare att läsa av än en annan. I den här studien framkommer det att färg kan både förtydliga, förstärka, förvirra, separera, sammanlänka och skapa nya associationer. Färg kan även attrahera och pedagogisera om det används rätt i sammanhanget.

    Fulltekst (pdf)
    Image as a first impression - how stylized images on the cover of a brochure can be designed to reflect and convey the message
  • 167.
    de Flon, Oliva
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    En Studie i Känslor - Hur väl uppfattas emotionella ansiktsuttryck hos en Disney-karaktär av åskådare?2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Animerad film blir alltmer populär och i takt med detta ökar kraven hos tittarna på verklighetstrogna och relaterbara animerade karaktärer. En stor del av det som gör en animerad karaktär relaterbar är dess ansiktsuttryck och förmåga att uttrycka igenkänningsbara känslor. Därför behandlar denna rapport en studie som undersöker hur väl emotionella ansiktsuttryck i en traditionellt animerad Disney-film uppfattas av åskådare. Studien tar stöd i ett antal teoretiska källor som behandlar ämnen såsom överdrift i animering, digitalisering av tecknande samt emotionell uttrycksfullhet. För att genomföra undersökningen användes en kvantitativ enkät och en kompletterande ingående intervju som datainsamlingsmetoder. Studiens resultat var att hälften av enkätrespondenternas svar, samt två av tio av intervjurespondentens svar, stämde överens med de svar som författaren bestämt var korrekta utifrån filmens kontext. Slutsatsen var därmed att den emotionella uttrycksfullheten inte förmedlas bra, men även att en annan sorts studie krävs för att göra en mer rättvis bedömning av frågan.

    Fulltekst (pdf)
    A Study in Emotion: How well are emotional facial expressions found in a Disney character perceived by viewers?
  • 168.
    Deligiannis, Johannes
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Real-Time Rendering of Soft Shadows2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis presents a method to render real time soft shadows efficiently on modern GPU’s using a combination of low discrepancy sampling sequences and spatiotemporal convolution. A theoretical foundation of shadows and shadow rendering will be presented together with common algorithms used for shadow rendering and light space convolution. The method presented is a reasonable candidate for games and other interactive applications aiming to provide visually pleasing soft shadows.

    Fulltekst (pdf)
    Real-Time Rendering of Soft Shadows
  • 169.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik.
    Weighted multi-dimensional logic programming2004Inngår i: 4th International Workshop on Computational Logic in Multi-Agent Systems,2004, New York, NY, USA: Springer Verlag , 2004, s. 178-Konferansepaper (Fagfellevurdert)
  • 170.
    Dell'Acqua, Pierangelo
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Klompstra, Leonie Verheijden
    Linköpings universitet, Institutionen för samhälls- och välfärdsstudier, Hälsa, Aktivitet, Vård (HAV). Linköpings universitet, Hälsouniversitetet.
    Jaarsma, Tiny
    Linköpings universitet, Institutionen för samhälls- och välfärdsstudier, Hälsa, Aktivitet, Vård (HAV). Linköpings universitet, Hälsouniversitetet.
    Samini, Ali
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    An Assistive Tool for Monitoring Physical Activities in Older Adults2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Active living in older adults reduces disabilities and increases quality of life. Adherence to physical activity is low in older adults, therefore new possibilities to motivate to exercise must be explored. One of this new possibilities is to use exergaming. In this paper, we present an assistive tool for monitoring daily, physical activities in older adults with access to exergaming in their home environments. The proposed system employs the Kinect device and allows one to analyse the body movements. From a pilot study, we proved that the system can detect movements through exergaming. In the future we plan to implement the developed monitoring tool as well as exergaming in nursing homes.

  • 171.
    Delsol, Ebba
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Kurtson Bellman, Matilda
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Att kommunicera varumärkesidentitet genom rörlig grafik2015Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [en]

    Denna studie syftar till att undersöka huruvida rörlig grafik är ett effektivt sätt att kommunicera företaget Prodeloxs varumärkesidentitet för en potentiell målgrupp. För att kunna uppfylla studiens syfte genomfördes en kvalitativ fallstudie. Ett teoriramverk berörande utformning av infografik, rörlig grafik och ett företags varumärkesidentitet togs först fram som en grund. Data samlades sedan in via kvalitativa intervjuer med anställda på Prodelox och en prototyp i form av rörlig grafik utformades med syfte att kommunicera företagets varumärkesidentitet. För att kunna dra slutsatser och jämföra huruvida den rörliga grafiken effektivt kommunicerade Prodelox varumärkesidentitet utformades även en prototyp på statisk grafik. Den rörliga grafiken och den statiska grafiken visades sedan för två fokusgrupper som diskuterade huruvida effektivt vardera grafik kommunicerade och ifall någon var mer lockande än den andra. Studien kom fram till att Prodeloxs varumärkesidentitet gick att gestaltas i rörlig grafik och att fler kommunikativa fördelar fanns med den rörliga grafiken i jämförelse med den statiska. Slutsatsen som drogs var att Prodelox kan använda sig att rörlig grafik för att effektivt kommunicera deras varumärkesidentitet till en potentiell målgrupp.

    Fulltekst (pdf)
    fulltext
  • 172.
    Dickner, Nils
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Lind, Johan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Information visualization and interaction design adapted for intelligent environment systems2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today there are many IT-systems holding information about different things. The information can for example be anything from news feeds to complex environment systems. By making these system collaborate with each other new oppurtunities and functionality can be established. However, since most of the systems are developed individually, there are different ways to communicate with each system. Therefore, The IT-agency Gaia has started a collaboration with the real estate company Klövern AB. The intention was to develop a plat- form for functional- and informational distribution focusing on commercial real estates. The platform was supposed to be available for Klöverns tenants and be used in public environments providing access to intelligent environment systems, processes in facility management and interactive information channels. This report describes the user study, the idea development and the implementation of two Windows 8 Metro application prototypes communicating through this platform. The two prototypes was directed towards the Cnema and Gaia which are both tenants of Klövern. Furthermore, both the applications was written in C# and uses ASP.Net library Signalr for real-time communication.

    Fulltekst (pdf)
    fulltext
  • 173.
    Dieckmann, Mark E
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Collisionless tangential discontinuity between pair plasma and electron–proton plasma2020Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 27, nr 3, artikkel-id 032105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study with a one-dimensional particle-in-cell simulation the expansion of a pair cloud into a magnetized electron–proton plasma as well as the formation and subsequent propagation of a tangential discontinuity that separates both plasmas. Its propagation speed takes the value that balances the magnetic pressure of the discontinuity against the thermal pressure of the pair cloud and the ram pressure of the protons. Protons are accelerated by the discontinuity to a speed that exceeds the fast magnetosonic speed by the factor of 10. A supercritical fast magnetosonic shock forms at the front of this beam. An increasing proton temperature downstream of the shock and ahead of the discontinuity leaves the latter intact. We create the discontinuity by injecting a pair cloud at a simulation boundary into a uniform electron–proton plasma, which is permeated by a perpendicular magnetic field. Collisionless tangential discontinuities in the relativistic pair jets of x-ray binaries (microquasars) are in permanent contact with the relativistic leptons of their inner cocoon, and they become the sources of radio synchrotron emissions.

    Fulltekst (pdf)
    fulltext
  • 174.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ahmed, H.
    Queens University of Belfast, North Ireland.
    Doria, D.
    Queens University of Belfast, North Ireland.
    Sarri, G.
    Queens University of Belfast, North Ireland.
    Walder, R.
    University of Lyon, France.
    Folini, D.
    University of Lyon, France.
    Bret, A.
    University of Castilla La Mancha, Spain.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Borghesi, M.
    Queens University of Belfast, North Ireland.
    Thin-shell instability in collisionless plasma2015Inngår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, nr 3, s. 031101-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin-shell instability is one process which can generate entangled structures in astrophysical plasma on collisional (fluid) scales. It is driven by a spatially varying imbalance between the ram pressure of the inflowing upstream plasma and the downstreams thermal pressure at a nonplanar shock. Here we show by means of a particle-in-cell simulation that an analog process can destabilize a thin shell formed by two interpenetrating, unmagnetized, and collisionless plasma clouds. The amplitude of the shells spatial modulation grows and saturates after about ten inverse proton plasma frequencies, when the shell consists of connected piecewise linear patches.

    Fulltekst (pdf)
    fulltext
  • 175.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Alejo, Aaron
    Centre for Plasma Physics, Queen's University Belfast, Belfast, UK..
    Sarri, Gianluca
    Centre for Plasma Physics, Queen's University Belfast, Belfast, UK..
    Folini, Doris
    Université de Lyon, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon, Lyon, France.
    Walder, Rolf
    Université de Lyon, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon, Lyon, France.
    One-dimensional thermal pressure-driven expansion of a pair cloud into an electron-proton plasma2018Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 25, nr 5, artikkel-id 064502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, a filamentation instability was observed when a laser-generated pair cloud interacted with an ambient plasma. The magnetic field it drove was strong enough to magnetize and accelerate the ambient electrons. It is of interest to determine if and how pair cloud-driven instabilities can accelerate ions in the laboratory or in astrophysical plasma. For this purpose, the expansion of a localized pair cloud with the temperature 400 keV into a cooler ambient electron-proton plasma is studied by means of one-dimensional particle-in-cell simulations. The cloud's expansion triggers the formation of electron phase space holes that accelerate some protons to MeV energies. Forthcoming lasers might provide the energy needed to create a cloud that can accelerate protons.

    Fulltekst (pdf)
    fulltext
  • 176.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Bret, Antoine
    ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain..
    Electrostatic and magnetic instabilities in the transition layer of a collisionless weakly relativistic pair shock2018Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 473, nr 1, s. 198-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Energetic electromagnetic emissions by astrophysical jets like those that are launched during the collapse of a massive star and trigger gamma-ray bursts are partially attributed to relativistic internal shocks. The shocks are mediated in the collisionless plasma of such jets by the filamentation instability of counterstreaming particle beams. The filamentation instability grows fastest only if the beams move at a relativistic relative speed. We model here with a particle-in-cell simulation, the collision of two cold pair clouds at the speed c/2 (c: speed of light). We demonstrate that the two-stream instability outgrows the filamentation instability for this speed and is thus responsible for the shock formation. The incomplete thermalization of the upstream plasma by its quasi-electrostatic waves allows other instabilities to grow. A shock transition layer forms, in which a filamentation instability modulates the plasma far upstream of the shock. The inflowing upstream plasma is progressively heated by a two-stream instability closer to the shock and compressed to the expected downstream density by the Weibel instability. The strong magnetic field due to the latter is confined to a layer 10 electron skin depths wide.

    Fulltekst (pdf)
    fulltext
  • 177.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Doria, D.
    Queens University of Belfast, North Ireland.
    Sarri, G.
    Queens University of Belfast, North Ireland.
    Romagnani, L.
    Ecole Polytech, France.
    Ahmed, H.
    Queens University of Belfast, North Ireland.
    Folini, D.
    University of Lyon, France.
    Walder, R.
    University of Lyon, France.
    Bret, A.
    University of Castilla La Mancha, Spain; Institute Invest Energet and Aplicac Ind, Spain.
    Borghesi, M.
    Queens University of Belfast, North Ireland.
    Electrostatic shock waves in the laboratory and astrophysics: similarities and differences2018Inngår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, nr 1, artikkel-id 014014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Contemporary lasers allow us to create shocks in the laboratory that propagate at a speed that matches that of energetic astrophysical shocks like those that ensheath supernova blast shells. The rapid growth time of the shocks and the spatio-temporal resolution, with which they can be sampled, allow us to identify the processes that are involved in their formation and evolution. Some laser-generated unmagnetized shocks are mediated by collective electrostatic forces and effects caused by binary collisions between particles can be neglected. Hydrodynamic models, which are valid for many large-scale astrophysical shocks, assume that collisions enforce a local thermodynamic equilibrium in the medium; laser-generated shocks are thus not always representative for astrophysical shocks. Laboratory studies of shocks can improve the understanding of their astrophysical counterparts if we can identify processes that affect electrostatic shocks and hydrodynamic shocks alike. An example is the nonlinear thin-shell instability (NTSI). We show that the NTSI destabilises collisionless and collisional shocks by the same physical mechanism.

    Fulltekst (pdf)
    fulltext
  • 178.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Doria, Domenico
    School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast, United Kingdom.
    Ahmed, Hamad
    School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast, United Kingdom.
    Romagnani, Lorenzo
    LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Palaiseau, France.
    Sarri, Gianluca
    School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast, United Kingdom.
    Folini, Doris
    Université de Lyon, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, Lyon, France.
    Walder, Rolf
    Université de Lyon, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, Lyon, France.
    Bret, Antoine
    ETSI Industriales, Universidad de Castilla-La Mancha, Ciudad Real, Spain.
    Borghesi, Marco
    School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast, United Kingdom.
    Expansion of a radial plasma blast shell into an ambient plasma2017Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 24, nr 9, artikkel-id 094501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of a radial blast shell into an ambient plasma is modeled with a particle-in-cell simulation. The unmagnetized plasma consists of electrons and protons. The formation and evolution of an electrostatic shock is observed, which is trailed by ion-acoustic solitary waves that grow on the beam of the blast shell ions in the post-shock plasma. In spite of the initially radial symmetric outflow, the solitary waves become twisted and entangled and, hence, they break the radial symmetry of the flow. The waves and their interaction with the shocked ambient ions slow down the blast shell protons and bring the post-shock plasma closer to equilibrium.

    Fulltekst (pdf)
    fulltext
  • 179.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Falk, Martin
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Steneteg, Peter
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Folini, Doris
    CRAL, École Normale Supérieure, 69622 Lyon, France.
    Hotz, Ingrid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nordman, Aida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Walder, Rolf
    CRAL, École Normale Supérieure, 69622 Lyon, France.
    Structure of a collisionless pair jet in a magnetizedelectron-proton plasma: Flow-aligned magnetic field2019Inngår i: High Energy Phenomena in Relativistic Outflows VII (HEPRO VII): Formation and propagation of relativistic outflows, Sissa Medialab srl, 2019, artikkel-id 006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present the results from a particle-in-cell (PIC) simulation that models the interaction between a spatially localized electron-positron cloud and an electron-ion plasma. The latter is permeated by a magnetic field that is initially spatially uniform and aligned with the mean velocity vector of the pair cloud. The pair cloud expels the magnetic field and piles it up into an electromagnetic piston. Its electromagnetic field is strong enough to separate the pair cloud from the ambient plasma in the direction that is perpendicular to the cloud propagation direction. The piston propagates away from the spine of the injected pair cloud and it accelerates the protons to a high nonrelativistic speed. The accelerated protons form an outer cocoon that will eventually become separated from the unperturbed ambient plasma by a fast magnetosonic shock. No electromagnetic piston forms at the front of the cloud and a shock is mediated here by the filamentation instability. The final plasma distribution resembles that of a hydrodynamic jet. Collisionless plasma jets may form in the coronal plasma of accreting black holes and the interaction between the strong magnetic field of the piston and the hot pair cloud may contribute to radio emissions by such objects.

  • 180.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Folini, Doris
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69622 Lyon, France.
    Bret, Antoine
    Universidad de Castilla La Mancha, ETSI Ind, E-13071 Ciudad Real, Spain.
    Walder, Rolf
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69622 Lyon, France.
    Simulation studies of temperature anisotropy driven pair-Alfvén and aperiodic instabilities in magnetized pair plasma2019Inngår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 61, nr 8, artikkel-id 085027Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We compare with one-dimensional particle-in-cell simulations the aperiodically growing instabilities driven by a bi-Maxwellian velocity distribution in unmagnetized electron plasma (Weibel instability) and in pair plasma. The simulation box is aligned with the cool direction. The waves in both simulations evolve towards a circularly polarized non-propagating magnetic structure. Its current and magnetic field are aligned and the structure is in a force-free state. We examine how a background magnetic field B 0, which is parallel to the simulation direction, affects the waves in the pair plasma. A weak B 0 cannot inhibit the growth of the aperiodically growing instability but it prevents it from reaching the force-free stable state. The mode collapses and seeds a pair Alfvén waves. An intermediate B 0 couples the thermal anisotropy to the pair Alfvén mode and propagating magnetowaves grow. The phase speed of the pair of Alfvén waves is increased by the thermal anisotropy. Its growth is suppressed when B 0 is set to the value that stabilizes the mirror mode.

    Fulltekst (pdf)
    fulltext
  • 181.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Folini, Doris
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, Lyon, France .
    Hotz, Ingrid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Nordman, Aida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Dell'Acqua, Pierangelo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Walder, Rolf
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, Lyon, France .
    Structure of a collisionless pair jet in a magnetized electron–proton plasma: flow-aligned magnetic field2019Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 621, artikkel-id A142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims. We study the effect a guiding magnetic field has on the formation and structure of a pair jet that propagates through a collisionless electron–proton plasma at rest.

    Methods. We model with a particle-in-cell (PIC) simulation a pair cloud with a temperature of 400 keV and a mean speed of 0.9c (c - light speed). Pair particles are continuously injected at the boundary. The cloud propagates through a spatially uniform, magnetized, and cool ambient electron–proton plasma at rest. The mean velocity vector of the pair cloud is aligned with the uniform background magnetic field. The pair cloud has a lateral extent of a few ion skin depths.

    Results. A jet forms in time. Its outer cocoon consists of jet-accelerated ambient plasma and is separated from the inner cocoon by an electromagnetic piston with a thickness that is comparable to the local thermal gyroradius of jet particles. The inner cocoon consists of pair plasma, which lost its directed flow energy while it swept out the background magnetic field and compressed it into the electromagnetic piston. A beam of electrons and positrons moves along the jet spine at its initial speed. Its electrons are slowed down and some positrons are accelerated as they cross the head of the jet. The latter escape upstream along the magnetic field, which yields an excess of megaelectronvolt positrons ahead of the jet. A filamentation instability between positrons and protons accelerates some of the protons, which were located behind the electromagnetic piston at the time it formed, to megaelectronvolt energies.

    Conclusions. A microscopic pair jet in collisionless plasma has a structure that is similar to that predicted by a hydrodynamic model of relativistic astrophysical pair jets. It is a source of megaelectronvolt positrons. An electromagnetic piston acts as the contact discontinuity between the inner and outer cocoons. It would form on subsecond timescales in a plasma with a density that is comparable to that of the interstellar medium in the rest frame of the latter. A supercritical fast magnetosonic shock will form between the pristine ambient plasma and the jet-accelerated plasma on a timescale that exceeds our simulation time by an order of magnitude.

  • 182.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Folini, Doris
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69007 Lyon, France.
    Walder, Rolf
    École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69007 Lyon, France.
    Romagnani, Lorenzo
    École Polytechnique, CNRS, LULI, F-91128 Palaiseau, France.
    d'Humieres, Emanuel
    Univ Bordeaux, IMB, UMR 5251, F-33405 Talence, France.
    Bret, Antoine
    ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real and Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real, Spain.
    Karlsson, Tomas
    KTH Royal Institute of Technology, School of Electrical Engineering, Space and Plasma Physics, Stockholm, Sweden.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Emergence of MHD structures in a collisionless PIC simulation plasma2017Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 24, nr 9, artikkel-id 094502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of a dense plasma into a dilute plasma across an initially uniform perpendicular magnetic field is followed with a one-dimensional particle-in-cell simulation over magnetohydrodynamics time scales. The dense plasma expands in the form of a fast rarefaction wave. The accelerated dilute plasma becomes separated from the dense plasma by a tangential discontinuity at its back. A fast magnetosonic shock with the Mach number 1.5 forms at its front. Our simulation demonstrates how wave dispersion widens the shock transition layer into a train of nonlinear fast magnetosonic waves.

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  • 183.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Moreno, Quentin
    Universite de Bordeaux, CNRS, CEA, CELIA, Talence, France.
    Doria, Domenico
    Centre for Plasma Physics (CPP), Queen's University Belfast, UK.
    Romagnani, Lorenzo
    Ecole Polytechnique, CNRS, LULI, Palaiseau, France.
    Sarri, Gianluca
    Centre for Plasma Physics (CPP), Queen's University Belfast, UK.
    Folini, Doris
    Ecole Nationale Superieure, Lyon, CRAL, Universite de Lyon, France.
    Walder, Rolf
    Ecole Nationale Superieure, Lyon, CRAL, Universite de Lyon, France.
    Bret, Antoiine
    ETSI Industriales, Universidad de Castilla-La Mancha, Spain.
    d'Humieres, Emmanuel
    Universite de Bordeaux, CNRS, CEA, CELIA, Talence, France.
    Borghesi, Marco
    Centre for Plasma Physics (CPP), Queen's University Belfast, UK.
    Expansion of a radially symmetric blast shell into a uniformly magnetized plasma2018Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 25, nr 5, artikkel-id 052108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of a thermal pressure-driven radial blast shell into a dilute ambient plasma is examined with two-dimensional PIC simulations. The purpose is to determine if laminar shocks form in a collisionless plasma which resemble their magnetohydrodynamic counterparts. The ambient plasma is composed of electrons with the temperature of 2 keV and cool fully ionized nitrogen ions. It is permeated by a spatially uniform magnetic field. A forward shock forms between the shocked ambient medium and the pristine ambient medium, which changes from an ion acoustic one through a slow magnetosonic one to a fast magnetosonic shock with increasing shock propagation angles relative to the magnetic field. The slow magnetosonic shock that propagates obliquely to the magnetic field changes into a tangential discontinuity for a perpendicular propagation direction, which is in line with the magnetohydrodynamic model. The expulsion of the magnetic field by the expanding blast shell triggers an electron-cyclotron drift instability.

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  • 184.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Sarri, G.
    Queens University of Belfast, North Ireland.
    Doria, D.
    Queens University of Belfast, North Ireland.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Borghesi, M.
    Queens University of Belfast, North Ireland.
    Particle-in-cell simulation study of a lower-hybrid shock2016Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 23, nr 6, s. 062111-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of a magnetized high-pressure plasma into a low-pressure ambient medium is examined with particle-in-cell simulations. The magnetic field points perpendicular to the plasmas expansion direction and binary collisions between particles are absent. The expanding plasma steepens into a quasi-electrostatic shock that is sustained by the lower-hybrid (LH) wave. The ambipolar electric field points in the expansion direction and it induces together with the background magnetic field a fast E cross B drift of electrons. The drifting electrons modify the background magnetic field, resulting in its pile-up by the LH shock. The magnetic pressure gradient force accelerates the ambient ions ahead of the LH shock, reducing the relative velocity between the ambient plasma and the LH shock to about the phase speed of the shocked LH wave, transforming the LH shock into a nonlinear LH wave. The oscillations of the electrostatic potential have a larger amplitude and wavelength in the magnetized plasma than in an unmagnetized one with otherwise identical conditions. The energy loss to the drifting electrons leads to a noticeable slowdown of the LH shock compared to that in an unmagnetized plasma. Published by AIP Publishing.

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  • 185.
    Dieckmann, Mark E
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Sarri, Gianluca
    Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast, United Kingdom.
    Folini, Doris
    École Normale Supérieure, Université de Lyon, Lyon, France.
    Walder, Rolf
    École Normale Supérieure, Université de Lyon, Lyon, France.
    Borghesi, Marco
    Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast, United Kingdom.
    Cocoon formation by a mildly relativistic pair jet in unmagnetized collisionless electron-proton plasma2018Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 25, nr 11, artikkel-id 112903Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By modelling the expansion of a cloud of electrons and positrons with the temperature of 400 keV which propagates at the mean speed of 0.9c (c: speed of light) through an initially unmagnetized electron-proton plasma with a particle-in-cell simulation, we find a mechanism that collimates the pair cloud into a jet. A filamentation (beam-Weibel) instability develops. Its magnetic field collimates the positrons and drives an electrostatic shock into the electron-proton plasma. The magnetic field acts as a discontinuity that separates the protons of the shocked ambient plasma, known as the outer cocoon, from the jet's interior region. The outer cocoon expands at the speed of 0.15c along the jet axis and at 0.03c perpendicularly to it. The filamentation instability converts the jet's directed flow energy into magnetic energy in the inner cocoon. The magnetic discontinuity cannot separate the ambient electrons from the jet electrons. Both species rapidly mix and become indistinguishable. The spatial distribution of the positive charge carriers is in agreement with the distributions of the ambient material and the jet material predicted by a hydrodynamic model apart from a dilute positronic outflow that is accelerated by the electromagnetic field at the jet's head.

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  • 186.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ahmed, Hamad
    Center for Plasma Physics, Queen's University Belfast, UK.
    Sarri, Gianluca
    Center for Plasma Physics, Queen's University Belfast, UK.
    Doria, Domenico
    Center for Plasma Physics, Queen's University Belfast.
    Kourakis, Ioannis
    Center for Plasma Physics, Queen's University Belfast, UK.
    Romagnani, Lorenzo
    LULI, Ecole Polytechnique, Université Pierre et Marie Curie, Palaiseau, France.
    Pohl, Martin
    Institute of Physics & Astronomy, University of Potsdam, Germany .
    Borghesi, Marco
    Center for Plasma Physics, Queen's University Belfast, UK.
    Parametric study of non-relativistic electrostatic shocks and the structure of their transition layer2013Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 20, nr 4, s. 042111-1-042111-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.

  • 187.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Alejo, Aaron
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, UK.
    Sarri, Gianluca
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, UK.
    Expansion of a mildly relativistic hot pair cloud into an electron-proton plasma2018Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 25, nr 6, artikkel-id 062122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of a charge-neutral cloud of electrons and positrons with the temperature 1 MeV into an unmagnetized ambient plasma is examined with a 2D particle-in-cell simulation. The pair outflow drives solitary waves in the ambient protons. Their bipolar electric fields attract electrons of the outflowing pair cloud and repel positrons. These fields can reflect some of the protons, thereby accelerating them to almost an MeV. Ion acoustic solitary waves are thus an efficient means to couple energy from the pair cloud to protons. The scattering of the electrons and positrons by the electric field slows down their expansion to a nonrelativistic speed. Only a dilute pair outflow reaches the expansion speed expected from the cloud's thermal speed. Its positrons are more energetic than its electrons. In time, an instability grows at the front of the dense slow-moving part of the pair cloud, which magnetizes the plasma. The instability is driven by the interaction of the outflowing positrons with the protons. These results shed light on how magnetic fields are created and ions are accelerated in pair-loaded astrophysical jets and winds.

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  • 188.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Bock, Alexander
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ahmed, Hamad
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, Belfast, UK.
    Doria, Domenico
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, Belfast, UK.
    Sarri, Gianluca
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, Belfast, UK.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Borghesi, Marco
    Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN, Belfast, UK.
    Shocks in unmagnetized plasma with a shear flow: Stability and magnetic field generation2015Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, nr 7, s. 1-9, artikkel-id 072104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A pair of curved shocks in a collisionless plasma is examined with a two-dimensional particle-in-cell simulation. The shocks are created by the collision of two electron-ion clouds at a speed that exceeds everywhere the threshold speed for shock formation. A variation of the collision speed along the initially planar collision boundary, which is comparable to the ion acoustic speed, yields a curvature of the shock that increases with time. The spatially varying Mach number of the shocks results in a variation of the downstream density in the direction along the shock boundary. This variation is eventually equilibrated by the thermal diffusion of ions. The pair of shocks is stable for tens of inverse ion plasma frequencies. The angle between the mean flow velocity vector of the inflowing upstream plasma and the shock's electrostatic field increases steadily during this time. The disalignment of both vectors gives rise to a rotational electron flow, which yields the growth of magnetic field patches that are coherent over tens of electron skin depths.

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  • 189.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Bret, Antoine
    University of Castilla La Mancha, ETSI Ind, Ciudad Real, Spain.
    Simulation study of the formation of a non-relativistic pair shock2017Inngår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 83, s. 1-19, artikkel-id 905830104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We examine with a particle-in-cell (PIC) simulation the collision of two equally dense clouds of cold pair plasma. The clouds interpenetrate until instabilities set in, which heat up the plasma and trigger the formation of a pair of shocks. The fastest-growing waves at the collision speed $c/5$, where $c$ is the speed of light in vacuum, and low temperature are the electrostatic two-stream mode and the quasi-electrostatic oblique mode. Both waves grow and saturate via the formation of phase space vortices. The strong electric fields of these nonlinear plasma structures provide an efficient means of heating up and compressing the inflowing upstream leptons. The interaction of the hot leptons, which leak back into the upstream region, with the inflowing cool upstream leptons continuously drives electrostatic waves that mediate the shock. These waves heat up the inflowing upstream leptons primarily along the shock normal, which results in an anisotropic velocity distribution in the post-shock region. This distribution gives rise to the Weibel instability. Our simulation shows that even if the shock is mediated by quasi-electrostatic waves, strong magnetowaves will still develop in its downstream region.

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  • 190.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Folini, Doris
    Centre de Recherche Astrophysique de Lyon UMR5574, Université de Lyon 1, ENS de Lyon, CNRS, F-69007 Lyon, France.
    Walder, Rolf
    Centre de Recherche Astrophysique de Lyon UMR5574, Université de Lyon 1, ENS de Lyon, CNRS, F-69007 Lyon, France.
    The interplay of the collisionless non-linear thin-shell instability with the ion acoustic instability2017Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 465, nr 4, s. 4240-4248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The non-linear thin-shell instability (NTSI) may explain some of the turbulent hydrodynamic structures that are observed close to the collision boundary of energetic astrophysical outflows. It develops in non-planar shells that are bounded on either side by a hydrodynamic shock, provided that the amplitude of the seed oscillations is sufficiently large. The hydrodynamic NTSI has a microscopic counterpart in collisionless plasma. A sinusoidal displacement of a thin shell, which is formed by the collision of two clouds of unmagnetized electrons and protons, grows and saturates on time-scales of the order of the inverse proton plasma frequency. Here we increase the wavelength of the seed perturbation by a factor of 4 compared to that in a previous study. Like in the case of the hydrodynamic NTSI, the increase in the wavelength reduces the growth rate of the microscopic NTSI. The prolonged growth time of the microscopic NTSI allows the waves, which are driven by the competing ion acoustic instability, to grow to a large amplitude before the NTSI saturates and they disrupt the latter. The ion acoustic instability thus imposes a limit on the largest wavelength that can be destabilized by the NTSI in collisionless plasma. The limit can be overcome by binary collisions. We bring forward evidence for an overstability of the collisionless NTSI.

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  • 191.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Quinn, Kevin
    Queen's University Belfast, UK.
    Sarri, Gianluca
    Queen's University Belfast, UK.
    Romagnani, Lorenzo
    LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Palaiseau, France.
    Murphy, Gareth Charles
    Dublin Institute for Advanced Studies, Dublin, Ireland.
    Kourakis, Ioannis
    Queen's University Belfast, UK.
    Macchi, Andrea
    CNR, Istituto Nazionale di Ottica, Pisa, Italy.
    Fuchs, Julien
    LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Palaiseau, France.
    Willi, Oswald
    Univ. Düsseldorf, Inst. Laser & Plasmaphys., Düsseldorf, Germany.
    Borghesi, Marco
    Queen's University Belfast.
    The Weibel instability in a circular rarefaction wave2012Inngår i: Proceedings of the 39th European Physical Society Conference & 16th Int. Congress on Plasma Physics, 2012, s. P1.176-1-P1.176-4Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Instabilities behind the front of a cylindrically expanding plasma have been investigated experimentally and with a particle-in-cell simulation. Tubelike filamentary structures form behind the front of a plasma created by irradiating wire targets with a ps-duration and intense ( 1019 W cm-2) laser pulse. These filaments exhibit coherent magnetic fields with a remarkable stability ( 103 / wp: plasma frequency). PIC simulations indicate that an instability driven by a thermal anisotropy of the electron population is the cause. This instability requires a plasma density gradient and hot electrons. It can thus contribute to the generation of strongsustained magnetic fields in astrophysical jets.

  • 192.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Sarri, Gianluca
    Queen's University of Belfast, UK.
    Borghesi, Marco
    Queen's University of Belfast, UK.
    Magnetic instability in a dilute circular rarefaction wave2012Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 19, nr 12, s. 122102-1-122102-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The growth of magnetic fields in the density gradient of a rarefaction wave has been observed in simulations and in laboratory experiments. The thermal anisotropy of the electrons, which gives rise to the magnetic instability, is maintained by the ambipolar electric field. This simple mechanism could be important for the magnetic field amplification in astrophysical jets or in the interstellar medium ahead of supernova remnant shocks. The acceleration of protons and the generation of a magnetic field by the rarefaction wave, which is fed by an expanding circular plasma cloud, is examined here in form of a 2D particle-in-cell simulation. The core of the plasma cloud is modeled by immobile charges, and the mobile protons form a small ring close to the cloud's surface. The number density of mobile protons is thus less than that of the electrons. The protons of the rarefaction wave are accelerated to 1/10 of the electron thermal speed, and the acceleration results in a thermal anisotropy of the electron distribution in the entire plasma cloud. The instability in the rarefaction wave is outrun by a TM wave, which grows in the dense core distribution, and its magnetic field expands into the rarefaction wave. This expansion drives a secondary TE wave.

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  • 193.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Sarri, Gianluca
    Queen's University Belfast, UK.
    Doria, Domenico
    Queen's University Belfast, UK.
    Ahmed, Hamad
    Queen's University Belfast, UK.
    Borghesi, Marco
    Queen's University Belfast, UK.
    Evolution of slow electrostatic shock into a plasma shock mediated by electrostatic turbulence2014Inngår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 16, s. 073001-1-073001-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The collision of two plasma clouds at a speed that exceeds the ion acoustic speed can result in the formation of shocks. This phenomenon is observed not only in astrophysical scenarios, such as the propagation of supernova remnant (SNR) blast shells into the interstellar medium, but also in laboratory-based laser-plasma experiments. These experiments and supporting simulations are thus seen as an attractive platform for small-scale reproduction and study of astrophysical shocks in the laboratory. We model two plasma clouds, which consist of electrons and ions, with a 2D particle-in-cell simulation. The ion temperatures of both clouds differ by a factor of ten. Both clouds collide at a speed that is realistic for laboratory studies and for SNR shocks in their late evolution phase, like that of RCW86. A magnetic field, which is orthogonal to the simulation plane, has a strength that is comparable to that of SNR shocks. A forward shock forms between the overlap layer of both plasma clouds and the cloud with cooler ions. A large-amplitude ion acoustic wave is observed between the overlap layer and the cloud with hotter ions. It does not steepen into a reverse shock because its speed is below the ion acoustic speed. A gradient of the magnetic field amplitude builds up close to the forward shock as it compresses the magnetic field. This gradient gives rise to an electron drift that is fast enough to trigger an instability. Electrostatic ion acoustic wave turbulence develops ahead of the shock, widens its transition layer, and thermalizes the ions, but the forward shock remains intact.

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  • 194.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Sarri, Gianluca
    Queen's University Belfast, UK.
    Doria, Domenico
    Queen's University Belfast, UK.
    Pohl, Martin
    University of Potsdam, Germany .
    Borghesi, Marco
    Queen's University Belfast, UK.
    Modification of the formation of high-Mach number electrostatic shock-like structures by the ion acoustic instability2013Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 20, nr 10, s. 102112-1-102112-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation of unmagnetized electrostatic shock-like structures with a high Mach number is examined with one-and two-dimensional particle-in-cell (PIC) simulations. The structures are generated through the collision of two identical plasma clouds, which consist of equally hot electrons and ions with a mass ratio of 250. The Mach number of the collision speed with respect to the initial ion acoustic speed of the plasma is set to 4.6. This high Mach number delays the formation of such structures by tens of inverse ion plasma frequencies. A pair of stable shock-like structures is observed after this time in the 1D simulation, which gradually evolves into electrostatic shocks. The ion acoustic instability, which can develop in the 2D simulation but not in the 1D one, competes with the nonlinear process that gives rise to these structures. The oblique ion acoustic waves fragment their electric field. The transition layer, across which the bulk of the ions change their speed, widens and their speed change is reduced. Double layer-shock hybrid structures develop.

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  • 195.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Sarri, Gianluca
    Queen's University Belfast. BT7 1NN, Belfast, United Kingdom.
    Markoff, Sera
    University of Amsterdam, 1098 XH Amsterdam, The Netherlands.
    Borghesi, Marco
    Queen's University Belfast, BT7 1NN, Belfast, United Kingdom.
    Zepf, Matt
    Queen's University Belfast, BT7 1NN, Belfast, United Kingdom.
    PIC simulation study of the interaction between a relativisticallymoving leptonic micro-cloud and ambient electrons.2015Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 577, nr A137, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. The jets of compact accreting objects are composed of electrons and a mixture of positrons and ions. These outflows impinge on the interstellar or intergalactic medium and both plasmas interact via collisionless processes. Filamentation (beam-Weibel) instabilities give rise to the growth of strong electromagnetic fields. These fields thermalize the interpenetrating plasmas.

    Aims. Hitherto, the effects imposed by a spatial non-uniformity on filamentation instabilities have remained unexplored. We examine the interaction between spatially uniform background electrons and a minuscule cloud of electrons and positrons. The cloud size is comparable to that created in recent laboratory experiments and such clouds may exist close to internal and external shocks of leptonic jets. The purpose of our study is to determine the prevalent instabilities, their ability to generate electromagnetic fields and the mechanism, by which the lepton micro-cloud transfers energy to the background plasma.

    Methods. A square micro-cloud of equally dense electrons and positrons impinges in our particle-in-cell (PIC) simulation on a spatially uniform plasma at rest. The latter consists of electrons with a temperature of 1 keV and immobile ions. The initially charge- and current neutral micro-cloud has a temperature of 100 keV and a side length of 2.5 plasma skin depths of the micro-cloud. The side length is given in the reference frame of the background plasma. The mean speed of the micro-cloud corresponds to a relativistic factor of 15, which is relevant for laboratory experiments and for relativistic astrophysical outflows. The spatial distributions of the leptons and of the electromagnetic fields are examined at several times.

    Results. A filamentation instability develops between the magnetic field carried by the micro-cloud and the background electrons. The electromagnetic fields, which grow from noise levels, redistribute the electrons and positrons within the cloud, which boosts the peak magnetic field amplitude. The current density and the moduli of the electromagnetic fields grow aperiodically in time and steadily along the direction that is anti-parallel to the cloud’s velocity vector. The micro-cloud remains conjoined during the simulation. The instability induces an electrostatic wakefield in the background plasma.

    Conclusions. Relativistic clouds of leptons can generate and amplify magnetic fields even if they have a microscopic size, which implies that the underlying processes can be studied in the laboratory. The interaction of the localized magnetic field and high-energy leptons will give rise to synchrotron jitter radiation. The wakefield in the background plasma dissipates the kinetic energy of the lepton cloud. Even the fastest lepton micro-clouds can be slowed down by this collisionless mechanism. Moderately fast charge- and current neutralized lepton micro–clouds will deposit their energy close to relativistic shocks and hence they do not constitute an energy loss mechanism for the shock.

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  • 196.
    Dieckmann, Mark Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Sarri, Gianluca
    Centre for Plasma Physics, Queen's University Belfast, UK.
    Murphy, Gareth
    Dublin Institute for Advanced Studies, Dublin, Ireland.
    Bret, Antoine
    Harvard-Smithsonian Center for Astrophysics.
    Romagnani, Lorenzo
    LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Palaiseau, France .
    Kourakis, Ioannis
    Centre for Plasma Physics, Queen's University Belfast, UK.
    Borghesi, Marco
    Centre for Plasma Physics, Queen's University Belfast, UK.
    Ynnerman, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Drury, Luke o'c
    Dublin Institute for Advanced Studies, Dublin, Ireland.
    PIC simulation of a thermal anisotropy-driven Weibel instability in a circular rarefaction wave2012Inngår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, nr 023007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expansion of an initially unmagnetized planar rarefaction wave has recently been shown to trigger a thermal anisotropy-driven Weibel instability (TAWI), which can generate magnetic fields from noise levels. It is examined here whether the TAWI can also grow in a curved rarefaction wave. The expansion of an initially unmagnetized circular plasma cloud, which consists of protons and hot electrons, into a vacuum is modelled for this purpose with a two-dimensional particle-in-cell (PIC) simulation. It is shown that the momentum transfer from the electrons to the radially accelerating protons can indeed trigger a TAWI. Radial current channels form and the aperiodic growth of a magnetowave is observed, which has a magnetic field that is oriented orthogonal to the simulation plane. The induced electric field implies that the electron density gradient is no longer parallel to the electric field. Evidence is presented here that this electric field modification triggers a second magnetic instability, which results in a rotational low-frequency magnetowave. The relevance of the TAWI is discussed for the growth of small-scale magnetic fields in astrophysical environments, which are needed to explain the electromagnetic emissions by astrophysical jets. It is outlined how this instability could be examined experimentally.

  • 197.
    Diepenbrock, Stefan
    et al.
    University of Münster, Germany.
    Ropinski, Timo
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    From Imprecise User Input to Precise Vessel Segmentations2012Inngår i: Eurographics Workshop on Visual Computing for Biology and Medicine, VCBM 2012, The Eurographics Association , 2012, s. 65-72Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Vessel segmentation is an important prerequisite for many medical applications. While automatic vessel segmentation is an active field of research, interaction and visualization techniques for semi-automatic solutions have gotten far less attention. Nevertheless, since automatic techniques do not generally achieve perfect results, interaction is necessary. Especially for tasks that require an in-detail inspection or analysis of the shape of vascular structures precise segmentations are essential. However, in many cases these can only be generated by incorporating expert knowledge. In this paper we propose a visual vessel segmentation system that allows the user to interactively generate vessel segmentations. Therefore, we employ multiple linked views which allow to assess different aspects of the segmentation and depict its different quality metrics. Based on these quality metrics, the user is guided, can assess the segmentation quality in detail and modify the segmentation accordingly. One common modification is the editing of branches, for which we propose a semi-automatic sketch-based interaction metaphor. Additionally, the user can also influence the shape of the vessel wall or the centerline through sketching. To assess the value of our system we discuss feedback from medical experts and have performed a thorough evaluation.

    Fulltekst (pdf)
    fulltext
  • 198.
    Dolo, Gilbert
    et al.
    University of Cape Town, South Africa.
    Haglund, Jesper
    Karlstad University, Sweden.
    Schönborn, Konrad
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Thermal Cameras as a Semiotic Resource for Inquiry in a South African Township School Context2018Inngår i: Designs for Learning, ISSN 1654-7608, Vol. 10, nr 1, s. 123-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inquiry-based approaches to science education are central to recent South African primary and secondary school curricula, but have been found challenging to adopt in disadvantaged township contexts. It is therefore important to find ways of introducing inquiry-based approaches, where pupils are encouraged to investigate phenomena they are interested in and to engage in true dialogue, as opposed to teacher-led triadic dialogue. We typically experience thermal phenomena through the sense of touch, but infrared (IR) cameras provide an additional opportunity to experience heat-related phenomena through the visual sense. Previously, in a Swedish context, we have found that hand-held IR cameras allow for strong pedagogical affordances and inspire pupils to engage in inquiry in the area of thermal science. In the present case study, grade 7 and 8 pupils (13–14 years old) in two South African township schools were introduced to IR cameras during predict-observe-explain (POE) exercises on heat conduction. The results revealed that if pupils had a sufficient conceptual understanding of heat conduction beforehand, they were capable of engaging in true dialogue in relation to the exercises and interpreting the thermal camera visual imagery. However, if pupils did not show such understanding, it was tempting for them and the facilitator to resort to triadic dialogue.

    Fulltekst (pdf)
    fulltext
  • 199.
    Dolo, Gilbert
    et al.
    University of Cape Town, South Africa.
    Haglund, Jesper
    Karlstad University, Sweden.
    Schönborn, Konrad
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik.
    Thermal Cameras as a Semiotic Resource for Teaching in South African Township Schools2019Inngår i: Book of Long Paper Abstracts, Symposia, Short Papers, Snapshots of the 27th Annual Meeting of the Southern African Association for Research in Mathematics, Science and Technology Education (SAARMSTE) / [ed] Good, M. & Stevenson-Milln, C., Durban, 2019, s. 460-463Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study investigates how thermal cameras can be used in meaning-making around thermal phenomena. Predict-observe-explain (POE) tasks were conducted with Grade 7 and 8 learners in two township schools. Results showed that learners coordinated multiple semiotic resources including dynamic thermal images, spoken language and touch in reasoning about heat and temperature. Although results support the literature in that inquiry-based approaches are challenging to implement in this context, the Grade 8 learners indicated that true dialogue was possible to achieve by demonstrating different lines of collaborative inquiry.

  • 200. Bestill onlineKjøp publikasjonen >>
    Domova, Veronika
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. ABB Corporate Research, Västerås.
    Designing visualization and interaction for industrial control rooms of the future2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    During the last decades, the industry has been undergoing extensive digitization leading to complex ensembles of humans, machines, autonomous agents, and sensors. With this new setup comes the challenge of how to appropriately support work-practices of industrial operators who now need to monitor and control complex industrial processes through remote interfaces. Information overflow and restrictive interfaces are two significant problems that operators face in their daily routines. In this PhD, I explore approaches to visualization and interaction that would reduce industrial operators' information load and enable them to perform their duties in an efficient, reliable, and safe manner. Industrial users and industrial settings are the starting points of my research.

    In this thesis, I describe multiple examples of custom-tailored data visualizations that reduce the operator's visual load by consolidating large amounts of data into compact overview displays with often nontrivial data presentation. With respect to interaction, I propose several tangible and tactile interfaces, as well as concepts for natural interaction, that let the user freely interact with the control station and the information it depicts. Finally, I propose several concepts of adaptive systems that adjust to the operator's context to ensure their high situational awareness and convenience of interaction.

    Even though this thesis is primarily intended for the community of interaction designers, I expect it to be of interest to a broader audience due to its relation to the user experience field. To a certain extent, everyone can resonate with the user's problems because, in our everyday life, we all are users of some technology and services. Furthermore, for a lay reader, this work can be seen as a comprehensive introduction to how the industry works and what role the human plays there.

    Delarbeid
    1. Visualization for Quality Healthcare: Patient Flow Exploration
    Åpne denne publikasjonen i ny fane eller vindu >>Visualization for Quality Healthcare: Patient Flow Exploration
    2019 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    The health and medical institutes and hospitalsare facing several challenges in the short and long term, i.e.demographic changes, demands on improving quality, limitedresources and cost requirements. To cope with these challenges,the health care sector needs to become more efficient, whilemaintaining and improving the quality of care. Efficient andtransparent information flow across the whole system plays a keyrole even in this context. Being able to analyze the patient flowsas the first step will provide the possibility to more efficientlymanage medical resources and better serve incoming patients. Inthis work, we have developed a web-based portal for interactiveanalysis of patient flow data to assist hospital authorities toimprove and optimize the time and quality of the providedservices. The developed tool facilitates short and long termoptimization of resource allocation by analyzing the past, as wellas current, patient flows, identifying bottlenecks and exploringthe reasons for the occurred waiting times.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-165581 (URN)
    Konferanse
    IEEE Big Data
    Tilgjengelig fra: 2020-05-06 Laget: 2020-05-06 Sist oppdatert: 2020-05-19
    2. Feel the Water: Expressing Physicality of District Heating Processes in Functional Overview Displays
    Åpne denne publikasjonen i ny fane eller vindu >>Feel the Water: Expressing Physicality of District Heating Processes in Functional Overview Displays
    2019 (engelsk)Inngår i: PROCEEDINGS OF THE 2019 ACM INTERNATIONAL CONFERENCE ON INTERACTIVE SURFACES AND SPACES (ISS 19), ASSOC COMPUTING MACHINERY , 2019, s. 229-240Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    This paper describes an explorative design study conducted in the scope of a collaborative research project in the district heating domain. In the scope of the project, we have arranged extensive field studies at two power plants to understand the workflows, problems, and needs of industrial operators. We relied on the gained knowledge to design and develop novel visual interfaces that would communicate the overall status of the district heating system at-a-glance. We aimed at exploring potential directions and alternatives beyond conventional industrial interfaces. One particular aspect of our research was related to how the physicality of the underlying industrial processes can be expressed by purely visual means. The paper introduces three high-fidelity prototypes demonstrating the novel visualizations developed. The paper explains the design choices made, namely the relation between the selected visual encodings to the requirements of the industrial operators tasks. Preliminary evaluation indicates industrial operators interest in the designed solutions. Future work will incorporate an extensive qualitative evaluation on site.

    sted, utgiver, år, opplag, sider
    ASSOC COMPUTING MACHINERY, 2019
    Emneord
    Data visualization; Process control; District heating; Industrial operator; Industrial interface; User-centered design
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-165361 (URN)10.1145/3343055.3359708 (DOI)000523231300022 ()978-1-4503-6891-9 (ISBN)
    Konferanse
    14th ACM International Conference on Interactive Surfaces and Spaces (ISS)
    Merknad

    Funding Agencies|strategic innovation program PIIA2; Wallenberg AI, Autonomous Systems and Software Program (WASP)3 - Knut and Alice Wallenberg Foundation

    Tilgjengelig fra: 2020-04-27 Laget: 2020-04-27 Sist oppdatert: 2020-05-10
    3. Towards Effective Industrial Robot Fleet Visualization for Remote Service Applications
    Åpne denne publikasjonen i ny fane eller vindu >>Towards Effective Industrial Robot Fleet Visualization for Remote Service Applications
    2017 (engelsk)Inngår i: 2017 IEEE 26th International Conference on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE) / [ed] Sumitra M. Reddy, Wojciech Cellary, and Mariagrazia Fugini, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 185-190Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    In recent years, advances in sensors, Internet and communication technologies opened many promising opportunities for remote services of industrial robots. With remote service applications, potential problems in robot systems can be detected before they happen, and prevented pro-actively avoiding costly production shut-downs. However, to be able to effectively perform remote service operations, remote support engineers need to analyse vast amounts of information. For a remote support engineer to be able to manage such amount of data, effective data visualization is crucial. Based on field studies and collected needs of support engineers working with industrial robots, we have designed and developed a prototype, i.e. one possible solution of an effective industrial fleet visualization, applied on the overheated robots use case. The initial validation of the prototype showed the benefits of such visual data presentation, as well as future directions.

    sted, utgiver, år, opplag, sider
    Institute of Electrical and Electronics Engineers (IEEE), 2017
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-152708 (URN)10.1109/WETICE.2017.40 (DOI)9781538617595 (ISBN)9781538617601 (ISBN)
    Konferanse
    The 26th International Conference on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE), 21-23 June 2017, Poznan, Poland
    Tilgjengelig fra: 2018-11-15 Laget: 2018-11-15 Sist oppdatert: 2020-05-10bibliografisk kontrollert
    4. Re-Introducing Physical User Interfaces into Industrial Control Rooms
    Åpne denne publikasjonen i ny fane eller vindu >>Re-Introducing Physical User Interfaces into Industrial Control Rooms
    Vise andre…
    2017 (engelsk)Inngår i: Proceedings of the European Conference on Cognitive Ergonomics 2017, New York: ACM Digital Library, 2017, s. 162-168Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Within industrial control rooms the trend has been to move away from physical towards digital interfaces. However, operators working in these control rooms have expressed feeling a loss of connection to the production process and machinery they are controlling. As such we present two prototypes Haptic Mouse and Shift Report Tool which were used to explore the re-introduction of physical user interfaces into industrial control rooms.

    sted, utgiver, år, opplag, sider
    New York: ACM Digital Library, 2017
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-152709 (URN)10.1145/3121283.3121295 (DOI)9781450352567 (ISBN)
    Konferanse
    The European Conference on Cognitive Ergonomics, ECCE 2017, Umeå, Sweden, September 19-22, 2017
    Tilgjengelig fra: 2018-11-15 Laget: 2018-11-15 Sist oppdatert: 2020-05-10bibliografisk kontrollert
    5. Towards intelligent alarm management in the Age of IIoT
    Åpne denne publikasjonen i ny fane eller vindu >>Towards intelligent alarm management in the Age of IIoT
    2017 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    In recent years, IIoT continues to gain tractionintroducing promising opportunities to build powerful systemsand applications with new benefits to industry. However, as theindustrial systems become more complex, the number of alarmcalls in plants has exploded to a very large number. Having toomany alarms to handle hinders operators from taking the rightdecisions at the right time which potentially can lead to safety,reliability, privacy, and security issues. The work presentedin this paper is aimed at improving the safety of industrialoperations by better managing alarms and also increasing thereliability of the industrial operation by ensuring the processesare reliable. A main outcome of the project is a set of alarmdata mining algorithms and a high-fidelity prototype of a userinterface for reviewing and analyzing the mined alarm data.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-165578 (URN)
    Konferanse
    Global Internet of Things Summit
    Tilgjengelig fra: 2020-05-06 Laget: 2020-05-06 Sist oppdatert: 2020-05-10
    6. Supporting Maritime Remote Experts Working Over Distance
    Åpne denne publikasjonen i ny fane eller vindu >>Supporting Maritime Remote Experts Working Over Distance
    2016 (engelsk)Inngår i: Supporting Maritime Remote Experts Working Over Distance, 2016Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Within the maritime domain there is a shift taking placetowards how troubleshooting (i.e. understanding andxing equipment issues) is being oered to maritimecustomers. Instead of travelling to ships around the world,service support engineers now remotely connect andaccess data from equipment sensors on-board. With thisgame-changing approach to xing equipment issues comesthe need to eectively support this change inwork-practice since engineers now need to solve complexproblems from an onshore location. Based on ndingsfrom eld studies, we present a prototype as a rst-steptowards addressing some of the key needs of theseengineers which include improving situation awareness forenhanced remote troubleshooting, integrating all relevantinformation for easier searching, and faster access torelevant personnel for help. The prototype was validatedwith domain specialists, and based on the ndings a set ofdesign recommendations is also presented.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-165577 (URN)
    Konferanse
    NordiCHI
    Tilgjengelig fra: 2020-05-06 Laget: 2020-05-06 Sist oppdatert: 2020-05-15
    7. Untethered Workspaces: A Zones Concept Towards Supporting Operator Movements In Control Rooms
    Åpne denne publikasjonen i ny fane eller vindu >>Untethered Workspaces: A Zones Concept Towards Supporting Operator Movements In Control Rooms
    2016 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Within industrial domains there is a need for control room operators to be in constant contact with the different processes they are responsible for controlling. With this responsibility comes the need to constantly be near their workstations in order to monitor, diagnose and quickly troubleshoot issues presented. These workstations, however, restrict operators in control rooms from moving freely within the control room itself, such as between their own and their colleague’s workstations since they cannot interact with the system from a distance. These systems also restrict those operators who need to continuously enter the control room from the plant/factory floor since interacting with process graphics requires them to remove all of their specialized equipment every time (e.g. large bulky safety gloves). We therefore present a concept for control room operators that supports their untethering from dedicated workstations, providing them with the ability to interact in a more flexible way.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-165562 (URN)
    Konferanse
    CHI
    Tilgjengelig fra: 2020-05-06 Laget: 2020-05-06 Sist oppdatert: 2020-05-10
    Fulltekst (pdf)
    fulltext
    Download (png)
    presentationsbild
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