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  • 251.
    Cervin, Albert
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Adaptive Hardware-accelerated Terrain Tessellation2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis report, a scheme for adaptive hardware terrain tessellation is presented. The scheme uses an offline processing approach where a height map is analyzed in terms of curvature and the result is stored in a resource called density map. This density map is then bound as a resource to the hardware tessellation stage and used to bias the tessellation factor for a given edge. The scheme is implemented inside FrostbiteTM2 by EATM DICETM and produces good results while making the heightfield rendering more efficient. The performance gain can be used to increase the rendering detail, allowing for better visual appearance for the terrain mesh. The scheme is currently implemented for hardware tessellation but could also be used for software terrain mesh generation. The implementation works satisfactory and produces good results with a reasonable speed.

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  • 252.
    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
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Improving the creation and reporting of structured findings during digital pathology review2016In: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 7, no 1, p. 32-32Article in journal (Refereed)
    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.

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  • 253.
    Cevey Tärnholm, Anton
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lacing a Chord Between Motor Skills and Sonification2023Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Detta arbete undersöker om sonifiering och användningen av ljud kan förstärka inlärning av sekvenser i muskelminnet. Specifikt undersöks inmatning av sekvenser på en modifierad numpad. Testerna går ut på att se om upprepade inmatningar av samma sekvens ger bättre resultat avseende tid och antal fel, med eller utan ljud som stöd. En annan aspekt som undersöks är ljudets påverkan på användarupplevelsen under denna typ av repetitiv träning. Resultaten visar att sonifiering har en effekt på hur snabbt användare lär sig vid träning av muskelminnet. Tiden det tar att mata in sekvensen minskar snabbare när sonifiering används, och en viss effekt ses även på antal fel. Användarupplevelsen visar också betydligt bättre resultat med ljud jämfört med utan.

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  • 254.
    Charlet, Arthur
    et al.
    Univ Lyon 1, Univ Lyon, ENS Lyon, CNRS,Ctr Rech Astrophys Lyon UMR5574, F-69230 St Genis Laval, France; Univ Montpellier, Lab Univers & Particules Montpellier LUPM, CNRS IN2P3, CC72,Pl Eugene Bataillon, F-34095 Montpellier 5, France.
    Walder, Rolf
    Univ Lyon 1, Univ Lyon, ENS Lyon, CNRS,Ctr Rech Astrophys Lyon UMR5574, F-69230 St Genis Laval, France.
    Marcowith, Alexandre
    Univ Montpellier, Lab Univers & Particules Montpellier LUPM, CNRS IN2P3, CC72,Pl Eugene Bataillon, F-34095 Montpellier 5, France.
    Folini, Doris
    Univ Lyon 1, Univ Lyon, ENS Lyon, CNRS,Ctr Rech Astrophys Lyon UMR5574, F-69230 St Genis Laval, France.
    Favre, J. M.
    Ctr Suisse Calcul Sci CSCS, Via Trevano 131, CH-6900 Lugano, Switzerland.
    Dieckmann, Mark Eric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Effects of radiative losses on the relativistic jets of high-mass microquasars2022In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 658, article id A100Article in journal (Refereed)
    Abstract [en]

    Context. Relativistic jets are ubiquitous in astrophysics. High-mass microquasars (HMMQs) are useful laboratories for studying these jets because they are relatively close and evolve over observable timescales. The ambient medium into which the jet propagates, however, is far from homogeneous. Corresponding simulation studies to date consider various forms of a wind-shaped ambient medium, but typically neglect radiative cooling and relativistic effects.

    Aims. We investigate the dynamical and structural effects of radiative losses and system parameters on relativistic jets in HMMQs, from the jet launch to its propagation over several tens of orbital separations.

    Methods. We used 3D relativistic hydrodynamical simulations including parameterized radiative cooling derived from relativistic thermal plasma distribution to carry out parameter studies around two fiducial cases inspired by Cygnus X-1 and Cygnus X-3.

    Results. Radiative losses are found to be more relevant in Cygnus X-3 than Cygnus X-1. Varying jet power, jet temperature, or the wind of the donor star tends to have a larger impact at early times, when the jet forms and instabilities initially develop, than at later times when the jet has reached a turbulent state.

    Conclusions. Radiative losses may be dynamically and structurally relevant at least for Cygnus X-3 and thus should be examined in more detail.

     

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  • 255.
    Chatzimparmpas, A.
    et al.
    Linnaeus Univ, Sweden.
    Paulovich, F. V
    Eindhoven Univ Technol, Netherlands.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    HardVis: Visual Analytics to Handle Instance Hardness Using Undersampling and Oversampling Techniques2023In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 42, no 1, p. 135-154Article in journal (Refereed)
    Abstract [en]

    Despite the tremendous advances in machine learning (ML), training with imbalanced data still poses challenges in many real-world applications. Among a series of diverse techniques to solve this problem, sampling algorithms are regarded as an efficient solution. However, the problem is more fundamental, with many works emphasizing the importance of instance hardness. This issue refers to the significance of managing unsafe or potentially noisy instances that are more likely to be misclassified and serve as the root cause of poor classification performance.This paper introduces HardVis, a visual analytics system designed to handle instance hardness mainly in imbalanced classification scenarios. Our proposed system assists users in visually comparing different distributions of data types, selecting types of instances based on local characteristics that will later be affected by the active sampling method, and validating which suggestions from undersampling or oversampling techniques are beneficial for the ML model. Additionally, rather than uniformly undersampling/oversampling a specific class, we allow users to find and sample easy and difficult to classify training instances from all classes. Users can explore subsets of data from different perspectives to decide all those parameters, while HardVis keeps track of their steps and evaluates the models predictive performance in a test set separately. The end result is a well-balanced data set that boosts the predictive power of the ML model. The efficacy and effectiveness of HardVis are demonstrated with a hypothetical usage scenario and a use case. Finally, we also look at how useful our system is based on feedback we received from ML experts.

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  • 256.
    Chatzimparmpas, Angelos
    et al.
    Northwestern University, USA.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnéuniversitetet, Institutionen för datavetenskap och medieteknik (DM).
    Visualization for Trust in Machine Learning Revisited: The State of the Field in 20232024In: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756Article in journal (Refereed)
    Abstract [en]

    Visualization for explainable and trustworthy machine learning remains one of the most important and heavily researched fields within information visualization and visual analytics with various application domains, such as medicine, finance, and bioinformatics. After our 2020 state-of-the-art report comprising 200 techniques, we have persistently collected peer-reviewed articles describing visualization techniques, categorized them based on the previously established categorization schema consisting of 119 categories, and provided the resulting collection of 542 techniques in an online survey browser. In this survey article, we present the updated findings of new analyses of this dataset as of fall 2023 and discuss trends, insights, and eight open challenges for using visualizations in machine learning. Our results corroborate the rapidly growing trend of visualization techniques for increasing trust in machine learning models in the past three years, with visualization found to help improve popular model explainability methods and check new deep learning architectures, for instance.

  • 257.
    Chatzimparmpas, Angelos
    et al.
    Linnaeus Univ, Sweden; Linnaeus Univ, Sweden.
    Martins, Rafael M.
    Linnaeus Univ, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    VisRuler: Visual analytics for extracting decision rules from bagged and boosted decision trees2023In: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 22, no 2, p. 115-139Article in journal (Refereed)
    Abstract [en]

    Bagging and boosting are two popular ensemble methods in machine learning (ML) that produce many individual decision trees. Due to the inherent ensemble characteristic of these methods, they typically outperform single decision trees or other ML models in predictive performance. However, numerous decision paths are generated for each decision tree, increasing the overall complexity of the model and hindering its use in domains that require trustworthy and explainable decisions, such as finance, social care, and health care. Thus, the interpretability of bagging and boosting algorithms-such as random forest and adaptive boosting-reduces as the number of decisions rises. In this paper, we propose a visual analytics tool that aims to assist users in extracting decisions from such ML models via a thorough visual inspection workflow that includes selecting a set of robust and diverse models (originating from different ensemble learning algorithms), choosing important features according to their global contribution, and deciding which decisions are essential for global explanation (or locally, for specific cases). The outcome is a final decision based on the class agreement of several models and the explored manual decisions exported by users. We evaluated the applicability and effectiveness of VisRuler via a use case, a usage scenario, and a user study. The evaluation revealed that most users managed to successfully use our system to explore decision rules visually, performing the proposed tasks and answering the given questions in a satisfying way.

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  • 258.
    Chatzimparmpas, Angelos
    et al.
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Martins, Rafael Messias
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Kucher, Kostiantyn
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    Empirical Study: Visual Analytics for Comparing Stacking to Blending Ensemble Learning2021In: Proceedings of the 23rd International Conference on Control Systems and Computer Science (CSCS23) / [ed] Ioan Dumitrache, Adina Magda Florea, Mihnea-Alexandru Moisescu, Florin Pop, and Alexandru Dumitraşcu, IEEE Computer Society , 2021, p. 1-8Conference paper (Other academic)
    Abstract [en]

    Stacked generalization (also called stacking) is an ensemble method in machine learning that uses a metamodel to combine the predictive results of heterogeneous base models arranged in at least one layer. K-fold cross-validation is employed at the various stages of training in this method. Nonetheless, another validation strategy is to try out several splits of data leading to different train and test sets for the base models and then use only the latter to train the metamodel—this is known as blending. In this work, we present a modification of an existing visual analytics system, entitled StackGenVis, that now supports the process of composing robust and diverse ensembles of models with both aforementioned methods. We have built multiple ensembles using our system with the two respective methods, and we tested the performance with six small- to large-sized data sets. The results indicate that stacking is significantly more powerful than blending based on three performance metrics. However, the training times of the base models and the final ensembles are lower and more stable during various train/test splits in blending rather than stacking.

  • 259.
    Chatzimparmpas, Angelos
    et al.
    Department of Computer Science and Media Technology, Linnaeus University, Växjö, Sweden.
    Martins, Rafael Messias
    Department of Computer Science and Media Technology, Linnaeus University, Växjö, Sweden.
    Kucher, Kostiantyn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Department of Computer Science and Media Technology, Linnaeus University, Växjö, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Department of Computer Science and Media Technology, Linnaeus University, Växjö, Sweden.
    FeatureEnVi: Visual Analytics for Feature Engineering Using Stepwise Selection and Semi-Automatic Extraction Approaches2022In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 28, no 4, p. 1773-1791Article in journal (Refereed)
    Abstract [en]

    The machine learning (ML) life cycle involves a series of iterative steps, from the effective gathering and preparation of the data—including complex feature engineering processes—to the presentation and improvement of results, with various algorithms to choose from in every step. Feature engineering in particular can be very beneficial for ML, leading to numerous improvements such as boosting the predictive results, decreasing computational times, reducing excessive noise, and increasing the transparency behind the decisions taken during the training. Despite that, while several visual analytics tools exist to monitor and control the different stages of the ML life cycle (especially those related to data and algorithms), feature engineering support remains inadequate. In this paper, we present FeatureEnVi, a visual analytics system specifically designed to assist with the feature engineering process. Our proposed system helps users to choose the most important feature, to transform the original features into powerful alternatives, and to experiment with different feature generation combinations. Additionally, data space slicing allows users to explore the impact of features on both local and global scales. FeatureEnVi utilizes multiple automatic feature selection techniques; furthermore, it visually guides users with statistical evidence about the influence of each feature (or subsets of features). The final outcome is the extraction of heavily engineered features, evaluated by multiple validation metrics. The usefulness and applicability of FeatureEnVi are demonstrated with two use cases and a case study. We also report feedback from interviews with two ML experts and a visualization researcher who assessed the effectiveness of our system.

  • 260.
    Chatzimparmpas, Angelos
    et al.
    Linnaeus University, Sweden.
    Martins, Rafael Messias
    Linnaeus University, Sweden.
    Kucher, Kostiantyn
    Linnaeus University, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    VisEvol: Visual Analytics to Support Hyperparameter Search through Evolutionary Optimization2021In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 40, no 3, p. 201-214Article in journal (Refereed)
    Abstract [en]

    During the training phase of machine learning (ML) models, it is usually necessary to configure several hyperparameters. This process is computationally intensive and requires an extensive search to infer the best hyperparameter set for the given problem. The challenge is exacerbated by the fact that most ML models are complex internally, and training involves trial-and-error processes that could remarkably affect the predictive result. Moreover, each hyperparameter of an ML algorithm is potentially intertwined with the others, and changing it might result in unforeseeable impacts on the remaining hyperparameters. Evolutionary optimization is a promising method to try and address those issues. According to this method, performant models are stored, while the remainder are improved through crossover and mutation processes inspired by genetic algorithms. We present VisEvol, a visual analytics tool that supports interactive exploration of hyperparameters and intervention in this evolutionary procedure. In summary, our proposed tool helps the user to generate new models through evolution and eventually explore powerful hyperparameter combinations in diverse regions of the extensive hyperparameter space. The outcome is a voting ensemble (with equal rights) that boosts the final predictive performance. The utility and applicability of VisEvol are demonstrated with two use cases and interviews with ML experts who evaluated the effectiveness of the tool.

  • 261.
    Chatzimparmpas, Angelos
    et al.
    Northwestern Univ, IL 60208 USA.
    Martins, Rafeal M.
    Linnaeus Univ, Sweden.
    Telea, Alexandru C.
    Univ Utrecht, Netherlands.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus Univ, Sweden.
    DeforestVis: Behaviour Analysis of Machine Learning Models with Surrogate Decision Stumps2024In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659Article in journal (Refereed)
    Abstract [en]

    As the complexity of machine learning (ML) models increases and their application in different (and critical) domains grows, there is a strong demand for more interpretable and trustworthy ML. A direct, model-agnostic, way to interpret such models is to train surrogate models-such as rule sets and decision trees-that sufficiently approximate the original ones while being simpler and easier-to-explain. Yet, rule sets can become very lengthy, with many if-else statements, and decision tree depth grows rapidly when accurately emulating complex ML models. In such cases, both approaches can fail to meet their core goal-providing users with model interpretability. To tackle this, we propose DeforestVis, a visual analytics tool that offers summarization of the behaviour of complex ML models by providing surrogate decision stumps (one-level decision trees) generated with the Adaptive Boosting (AdaBoost) technique. DeforestVis helps users to explore the complexity versus fidelity trade-off by incrementally generating more stumps, creating attribute-based explanations with weighted stumps to justify decision making, and analysing the impact of rule overriding on training instance allocation between one or more stumps. An independent test set allows users to monitor the effectiveness of manual rule changes and form hypotheses based on case-by-case analyses. We show the applicability and usefulness of DeforestVis with two use cases and expert interviews with data analysts and model developers. We present DeforestVis, a visual analytics tool that offers summarization of the behaviour of complex ML models by providing AdaBoost-based surrogate decision stumps. Our proposed tool helps users explore the complexity versus fidelity trade-off, create attribute-based explanations with weighted stumps, and analyse the impact of rule overriding. image

  • 262.
    Chatzimparmpas, Angelos
    et al.
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Park, Vilhelm
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    Evaluating StackGenVis with a Comparative User Study2022In: Proceedings of the 15th IEEE Pacific Visualization Symposium (PacificVis '22), IEEE , 2022, p. 161-165Conference paper (Refereed)
    Abstract [en]

    Stacked generalization (also called stacking) is an ensemble method in machine learning that deploys a metamodel to summarize the predictive results of heterogeneous base models organized into one or more layers. Despite being capable of producing high-performance results, building a stack of models can be a trial-and-error procedure. Thus, our previously developed visual analytics system, entitled StackGenVis, was designed to monitor and control the entire stacking process visually. In this work, we present the results of a comparative user study we performed for evaluating the StackGenVis system. We divided the study participants into two groups to test the usability and effectiveness of StackGenVis compared to Orange Visual Stacking (OVS) in an exploratory usage scenario using healthcare data. The results indicate that StackGenVis is significantly more powerful than OVS based on the qualitative feedback provided by the participants. However, the average completion time for all tasks was comparable between both tools.

  • 263.
    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
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    IEEE VISUAL ANALYTICS SCIENCE & TECHNOLOGY CONFERENCE, IEEE INFORMATION VISUALIZATION CONFERENCE, AND IEEE SCIENTIFIC VISUALIZATION CONFERENCE2014In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 20, no 12, p. XI-XIVArticle in journal (Other academic)
    Abstract [en]

    n/a

  • 264.
    Chow, Joyce A
    et al.
    RISE Interactive Institute, Norrköping, Sweden.
    Törnros, Martin E
    Interaktiva Rum Sverige, Gothenburg, Sweden.
    Waltersson, Marie
    Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Richard, Helen
    Region Östergötland, Center for Diagnostics, Clinical pathology.
    Kusoffsky, Madeleine
    RISE Interactive Institute, Norrköping, Sweden.
    Lundström, Claes
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Sectra AB, Linköping, Sweden.
    Kurti, Arianit
    RISE Interactive Institute, Norrköping, Sweden.
    A Design Study Investigating Augmented Reality and Photograph Annotation in a Digitalized Grossing Workstation2017In: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 8, no 31Article in journal (Refereed)
    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.

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  • 265.
    Chung, Michelle
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hansson, Victoria
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    The use of layoutprinciples for the creation of a uniform visual communication for printed marketing material2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    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.

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  • 266.
    Cleveson, Aron
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Sheet piling for permanent application in solid water hazards for construction of fishways.2014Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 267.
    Cocchioni, M.
    et al.
    Deep Blue, Italy.
    Bonelli, S.
    Deep Blue, Italy.
    Westin, Carl
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Borst, C.
    Delft Univ Technol, Netherlands.
    Bång, Magnus
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Hilburn, B.
    Ctr Human Performance Res, Netherlands.
    Learning for Air Traffic Management: guidelines for future AI systems2023In: 12TH EASN INTERNATIONAL CONFERENCE ON "INNOVATION IN AVIATION & SPACE FOR OPENING NEW HORIZONS", IOP PUBLISHING LTD , 2023, Vol. 2526, article id 012105Conference paper (Refereed)
    Abstract [en]

    The SESAR-funded Modern ATM via Human / Automation Learning Optimisation (MAHALO) project recently completed two years of technical work exploring the human performance impacts of AI and Machine Learning (ML), as applied to enroute ATC conflict detection and resolution (CD&R). It first developed a hybrid ML CD&R capability, along with a realtime simulation platform and experimental User Interface. After a series of development trials, the project culminated in a pair of field studies (i.e., human-in-the-loop trials) across two EU countries, with a total of 35 operational air traffic controllers. In each of these two field studies, controller behaviour was first captured in a pre-test phase, and used to train the ML system. Subsequent main experiment trials then experimentally manipulated within controllers both Conformance (as either a personalised-, group average-, or optimized model) and Transparency (as ether a baseline vector depiction, an enhanced graphical diagram, or a diagramplus-text presentation). The proposed paper presents guidelines on the design and implementation of ML systems in Air Traffic Control, derived from the results and lesson learned from the Simulations, as well as the qualitative feedback received from the controllers themselves.

  • 268.
    Cockburn, Andy
    et al.
    Univ Canterbury, New Zealand.
    Dragicevic, Pierre
    Inria, France.
    Besancon, Lonni
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gutwin, Carl
    Univ Saskatchewan, Canada; Univ Saskatchewan, Canada.
    Threats of a Replication Crisis in Empirical Computer Science2020In: Communications of the ACM, ISSN 0001-0782, E-ISSN 1557-7317, Vol. 63, no 8, p. 70-79Article, review/survey (Refereed)
    Abstract [en]

    Research replication only works if there is confidence built into the results.

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  • 269.
    Collin, Sofie
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Synthetic Data for Training and Evaluation of Critical Traffic Scenarios2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modern camera-based vehicle safety systems heavily rely on machine learning and consequently require large amounts of training data to perform reliably. However, collecting and annotating the needed data is an extremely expensive and time-consuming process. In addition, it is exceptionally difficult to collect data that covers critical scenarios. This thesis investigates to what extent synthetic data can replace real-world data for these scenarios. Since only a limited amount of data consisting of such real-world scenarios is available, this thesis instead makes use of proxy scenarios, e.g. situations when pedestrians are located closely in front of the vehicle (for example at a crosswalk). The presented approach involves training a detector on real-world data where all samples of these proxy scenarios have been removed and compare it to other detectors trained on data where the removed samples have been replaced with various degrees of synthetic data. A method for generating and automatically and accurately annotating synthetic data, using features in the CARLA simulator, is presented. Also, the domain gap between the synthetic and real-world data is analyzed and methods in domain adaptation and data augmentation are reviewed. The presented experiments show that aligning statistical properties between the synthetic and real-world datasets distinctly mitigates the domain gap. There are also clear indications that synthetic data can help detect pedestrians in critical traffic situations

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  • 270.
    Collins, Christopher
    et al.
    Ontario Tech University, Oshawa, Canada.
    Fokkens, Antske
    Free University, Amsterdam, Netherlands.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linnaeus University, Sweden.
    Weaver, Chris
    University of Oklahoma, Norman, USA.
    Chatzimparmpas, Angelos
    Linnaeus University, Department of Computer Science and Media Technology, ISOVIS Research Group, Sweden.
    Visual Text Analytics: Report from Dagstuhl Seminar 221912022Report (Other academic)
    Abstract [en]

    Text data is one of the most abundant types of data available, produced every day across all domains of society. Understanding the contents of this data can support important policy decisions, help us understand society and culture, and improve business processes. While machine learning techniques are growing in their power for analyzing text data, there is still a clear role for human analysis and decision-making. This seminar explored the use of visual analytics applied to text data as a means to bridge the complementary strengths of people and computers. The field of visual text analytics applies visualization and interaction approaches which are tightly coupled to natural language processing systems to create analysis processes and systems for examining text and multimedia data. During the seminar, interdisciplinary working groups of experts from visualization, natural language processing, and machine learning examined seven topic areas to reflect on the state of the field, identify gaps in knowledge, and create an agenda for future cross-disciplinary research. This report documents the program and the outcomes of Dagstuhl Seminar 22191 "Visual Text Analytics".

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  • 271.
    Conroy, Melanie
    et al.
    University of Memphis, USA.
    Gillmann, Christina
    Leipzig University, Germany.
    Harvey, Francis
    Leibniz Institute for Regional Geography, Germany; University of Warsaw, Poland.
    Mchedlidze, Tamara
    Utrecht University, The Netherlands.
    Fabrikant, Sara Irina
    University of Zürich, Switzerland.
    Windhager, Florian
    Danube University Krems, Austria.
    Scheuermann, Gerik
    Leipzig University, Germany.
    Tangherlini, Timothy R.
    University of California, Berkeley, USA.
    Warren, Christopher N.
    Carnegie Mellon University, USA.
    Weingart, Scott B.
    University of Edinburgh, UK.
    Rehbein, Malte
    Passau University, Germany.
    Börner, Katy
    Indiana University, Bloomington, USA.
    Elo, Kimmo
    University of Turku, Finland.
    Jänicke, Stefan
    University of Southern Denmark, Denmark.
    Kerren, Andreas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Department of Computer Science and Media Technology, Linnaeus University, Sweden.
    Nöllenburg, Martin
    TU Wien, Austria.
    Dwyer, Tim
    Monash University, Australia.
    Eide, Øyvind
    University of Cologne, Germany.
    Kobourov, Stephen
    University of Arizona, USA.
    Betz, Gregor
    Karlsruhe Institute of Technology, Germany.
    Uncertainty in humanities network visualization2024In: Frontiers in Communication, E-ISSN 2297-900X, Vol. 8, article id 1305137Article in journal (Refereed)
    Abstract [en]

    Network visualization is one of the most widely used tools in digital humanities research. The idea of uncertain or “fuzzy” data is also a core notion in digital humanities research. Yet network visualizations in digital humanities do not always prominently represent uncertainty. In this article, we present a mathematical and logical model of uncertainty as a range of values which can be used in network visualizations. We review some of the principles for visualizing uncertainty of different kinds, visual variables that can be used for representing uncertainty, and how these variables have been used to represent different data types in visualizations drawn from a range of non-humanities fields like climate science and bioinformatics. We then provide examples of two diagrams: one in which the variables displaying degrees of uncertainty are integrated into the graph and one in which glyphs are added to represent data certainty and uncertainty. Finally, we discuss how probabilistic data and what-if scenarios could be used to expand the representation of uncertainty in humanities network visualizations.

  • 272.
    Cooper, Matthew
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Fridlund, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Andel, Miroslav
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Bojan, Claudiu
    Eurocontrol, Luxembourg.
    Hardy, Jean-Luc
    Eurocontrol Experimental Centre, Brétigny.
    Educational Benefits of 3D Displays in Early Controller Training2010In: Proceedings of the 27th International Congress of the Aeronautical Sciences (ICAS2010) / [ed] Professor Ian Grant, 2010Conference paper (Other academic)
    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.

  • 273.
    Corell, Simon
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    A Recurrent Neural Network For Battery Capacity Estimations In Electrical Vehicles2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    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.

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    A Recurrent Neural Network For Battery Capacity Estimations In Electrical Vehicles
  • 274.
    Corin, Filippa
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Österling, Lovisa
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    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 credits / 30 HE creditsStudent thesis
    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.

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  • 275.
    Cossío, Fernando
    et al.
    Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden.
    Schurz, Haiko
    Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden.
    Engström, Mathias
    Collective Minds Radiology, Stockholm, Sweden.
    Barck-Holst, Carl
    West Code Group, Stockholm, Sweden.
    Tsirikoglou, Apostolia
    Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Gustafsson, Håkan
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Smith, Kevin
    Royal Institute of Technology (KTH), Division of Computational Science and Technology, Stockholm, Sweden.
    Zackrisson, Sophia
    Lund University, Department of Diagnostic Radiology, Translational Medicine, Malmö, Sweden.
    Strand, Fredrik
    Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden.
    VAI-B: a multicenter platform for the external validation of artificial intelligence algorithms in breast imaging2023In: Journal of Medical Imaging, ISSN 2329-4302, E-ISSN 2329-4310, Vol. 10, no 06Article in journal (Refereed)
    Abstract [en]

    Purpose: Multiple vendors are currently offering artificial intelligence (AI) computer-aided systems for triage detection, diagnosis, and risk prediction of breast cancer based on screening mammography. There is an imminent need to establish validation platforms that enable fair and transparent testing of these systems against external data.Approach: We developed validation of artificial intelligence for breast imaging (VAI-B), a platform for independent validation of AI algorithms in breast imaging. The platform is a hybrid solution, with one part implemented in the cloud and another in an on-premises environment at Karolinska Institute. Cloud services provide the flexibility of scaling the computing power during inference time, while secure on-premises clinical data storage preserves their privacy. A MongoDB database and a python package were developed to store and manage the data on-premises. VAI-B requires four data components: radiological images, AI inferences, radiologist assessments, and cancer outcomes.Results: To pilot test VAI-B, we defined a case-control population based on 8080 patients diagnosed with breast cancer and 36,339 healthy women based on the Swedish national quality registry for breast cancer. Images and radiological assessments from more than 100,000 mammography examinations were extracted from hospitals in three regions of Sweden. The images were processed by AI systems from three vendors in a virtual private cloud to produce abnormality scores related to signs of cancer in the images. A total of 105,706 examinations have been processed and stored in the database.Conclusions: We have created a platform that will allow downstream evaluation of AI systems for breast cancer detection, which enables faster development cycles for participating vendors and safer AI adoption for participating hospitals. The platform was designed to be scalable and ready to be expanded should a new vendor want to evaluate their system or should a new hospital wish to obtain an evaluation of different AI systems on their images.

  • 276.
    Costa, Jonathas
    et al.
    NYU, NY 10003 USA.
    Bock, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Univ Utah, UT 84112 USA.
    Emmart, Carter
    Amer Museum Nat Hist, NY 10024 USA.
    Hansen, Charles
    Univ Utah, UT 84112 USA.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Univ Utah, UT 84112 USA.
    Silva, Claudio
    NYU, NY 10003 USA.
    Interactive Visualization of Atmospheric Effects for Celestial Bodies2021In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 27, no 2, p. 785-795Article in journal (Refereed)
    Abstract [en]

    We present an atmospheric model tailored for the interactive visualization of planetary surfaces. As the exploration of the solar system is progressing with increasingly accurate missions and instruments, the faithful visualization of planetary environments is gaining increasing interest in space research, mission planning, and science communication and education. Atmospheric effects are crucial in data analysis and to provide contextual information for planetary data. Our model correctly accounts for the non-linear path of the light inside the atmosphere (in Earths case), the light absorption effects by molecules and dust particles, such as the ozone layer and the Martian dust, and a wavelength-dependent phase function for Mie scattering. The mode focuses on interactivity, versatility, and customization, and a comprehensive set of interactive controls make it possible to adapt its appearance dynamically. We demonstrate our results using Earth and Mars as examples. However, it can be readily adapted for the exploration of other atmospheres found on, for example, of exoplanets. For Earths atmosphere, we visually compare our results with pictures taken from the International Space Station and against the CIE clear sky model. The Martian atmosphere is reproduced based on available scientific data, feedback from domain experts, and is compared to images taken by the Curiosity rover. The work presented here has been implemented in the OpenSpace system, which enables interactive parameter setting and real-time feedback visualization targeting presentations in a wide range of environments, from immersive dome theaters to virtual reality headsets.

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  • 277.
    Costantini, Stefania
    et al.
    Dip. di Informatica, Universit` a di L’Aquila, L’Aquila, Italy.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    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 Agents2011In: 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, p. 250-265Conference paper (Refereed)
    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.

  • 278.
    Costantini, Stefania
    et al.
    Dept. of Computer Science, L'Aquila University, Italy.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    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 Events2010In: Experimental evaluation of algorithms for solving problems with combinatorial explosion / [ed] Marco Gavanelli and Toni Mancini, Bologna: CEUR , 2010Conference paper (Refereed)
  • 279.
    Costantini, Stefania
    et al.
    Dept. of Computer Science, L'Aquila University.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    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 Training2010In: Procs. Congresso Nazionale, Associazione Italiana per l’Informatica ed il Calcolo Automatico / [ed] Paola Inverardi, 2010Conference paper (Refereed)
  • 280.
    Costantini, Stefania
    et al.
    University of L'Aquila, Italy.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Pereira, Luis M
    New University of Lisbon, Portugal.
    Toni, Francesca
    Department of Computing, Imperial College London.
    Meta-axioms and Complex Preferences in Evolving Logical Agents2011In: / [ed] L. Antunes, H. S. Pinto, R. Prada and P. Trigo, Springer, 2011, p. 580-594Conference paper (Refereed)
  • 281.
    Crafoord, Carina
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Wik, Emma
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hur ett varumärke kan förmedla sina kärnvärden och en unisex-känsla i ett intresseväckande Instagramflöde2018Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    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.

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    Hur ett varumärke kan förmedla sina kärnvärden och en unisex-känsla i ett intresseväckande Instagramflöde
  • 282.
    Dahlin, Jesper
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Karlsson, Simon
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Streamline the production process using Lean 5S2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    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.

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  • 283.
    Dahlman, Pierre
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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 credits / 16 HE creditsStudent thesis
    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.

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    Design av grafiskt tryck för ökad jämlikhet inom skateboard - utformning av grafiskt tryck för att främka kvinnliga skateboardåkare
  • 284.
    Dai, Shaozhang
    et al.
    Monash University, Australia.
    Smiley, Jim
    Monash University, Australia.
    Dwyer, Tim
    Monash University, Australia.
    Ens, Barrett
    Monash University, Australia.
    Besançon, Lonni
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    RoboHapalytics: A Robot Assisted Haptic Controller for Immersive Analytics2023In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 29, no 1, p. 451-461Article in journal (Refereed)
    Abstract [en]

    Immersive environments offer new possibilities for exploring three-dimensional volumetric or abstract data. However, typicalmid-air interaction offers little guidance to the user in interacting with the resulting visuals. Previous work has explored the use of hapticcontrols to give users tangible affordances for interacting with the data, but these controls have either: been limited in their range andresolution; were spatially fixed; or required users to manually align them with the data space. We explore the use of a robot arm withhand tracking to align tangible controls under the user’s fingers as they reach out to interact with data affordances. We begin witha study evaluating the effectiveness of a robot-extended slider control compared to a large fixed physical slider and a purely virtualmid-air slider. We find that the robot slider has similar accuracy to the physical slider but is significantly more accurate than mid-airinteraction. Further, the robot slider can be arbitrarily reoriented, opening up many new possibilities for tangible haptic interaction withimmersive visualisations. We demonstrate these possibilities through three use-cases: selection in a time-series chart; interactiveslicing of CT scans; and finally exploration of a scatter plot depicting time-varying socio-economic data

  • 285.
    Danckwardt-Lillieström, Ebba
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Johansson, Steffanie
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Berätta för att lära: Tell to Learn2021Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Berättelser har funnits i urminnes tider där de använts för underhållning samt ett sätt att förmedla lärdomar. Alla berättelser bygger på någon typ av storytelling som innefattar en rad olika principer för att lyckas fånga mottagaren på olika sätt. Genom att fånga mottagarens intresse via text, ljud eller bild kan skaparen formulera ett budskap på ett fängslande sätt. Berättelser vill i många fall förklara verkligheten, stärka den moraliska kompassen eller väcka känslor inom oss. Att väva in lärdomar i berättelser kan leda till väckt empati och med stor sannolikhet nya beteenden om berättelsen lyckas fånga mottagarens uppmärksamhet. Syftet med denna studie var att utforma en visuell berättelse om en tomats livscykel anpassad till barn i åldern 2-6 år, för att på ett underhållande sätt öka medvetenhet kring livsmedlets resa till tallriken.

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  • 286.
    Danielsson, Melinda
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    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 credits / 16 HE creditsStudent thesis
    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.

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    Image as a first impression - how stylized images on the cover of a brochure can be designed to reflect and convey the message
  • 287.
    de Flon, Oliva
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    En Studie i Känslor - Hur väl uppfattas emotionella ansiktsuttryck hos en Disney-karaktär av åskådare?2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    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.

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    A Study in Emotion: How well are emotional facial expressions found in a Disney character perceived by viewers?
  • 288.
    Delavennat, Julien
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Physically-based Real-time Glare2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The theme of this master’s thesis is the real-time rendering of glare as seen through human eyes, as a post-processing effect applied to a first-person view in a 3D application. Several techniques already exist, and the basis for this project is a paper from 2009 titled Temporal Glare: Real-Time Dynamic Simulation of the Scattering in the Human Eye, by Ritschel et al. The goal of my project was initially to implement that paper as part of a larger project, but it turned out that there might be some opportunities to build upon aspects of the techniques described in Temporal Glare; in consequence these various opportunities have been explored and constitute the main substance of this project.

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  • 289.
    Deligiannis, Johannes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Real-Time Rendering of Soft Shadows2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

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    Real-Time Rendering of Soft Shadows
  • 290.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Weighted multi-dimensional logic programming2004In: 4th International Workshop on Computational Logic in Multi-Agent Systems,2004, New York, NY, USA: Springer Verlag , 2004, p. 178-Conference paper (Refereed)
  • 291.
    Dellacqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Costantini, Stefania
    Univ Laquila, Italy.
    Empathetic human-agent interaction via emotional behavior trees2023In: INTELLIGENZA ARTIFICIALE, ISSN 1724-8035, Vol. 17, no 1, p. 89-100Article in journal (Refereed)
    Abstract [en]

    To the aim of constructing effective human-AI teams, that can be useful for improving caregiving in medicine and enhancing human performance also in other sectors (i.e., teaching), agents which interact with humans should be endowed with an emotion recognition and management module, capable of empathy, and of modeling aspects of the Theory of Mind, in the sense of being able to reconstruct what someone is thinking or feeling. In this paper, we propose an architecture for such a module, based upon an enhanced notion of Behavior Trees. We illustrate the effectiveness of the proposed architecture on a significant example and on a wider case study.

  • 292.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Klompstra, Leonie Verheijden
    Linköping University, Department of Social and Welfare Studies, Division of Health, Activity and Care. Linköping University, Faculty of Health Sciences.
    Jaarsma, Tiny
    Linköping University, Department of Social and Welfare Studies, Division of Health, Activity and Care. Linköping University, Faculty of Health Sciences.
    Samini, Ali
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    An Assistive Tool for Monitoring Physical Activities in Older Adults2013Conference paper (Refereed)
    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.

  • 293.
    Delsol, Ebba
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Kurtson Bellman, Matilda
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Att kommunicera varumärkesidentitet genom rörlig grafik2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 294.
    Dickner, Nils
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lind, Johan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Information visualization and interaction design adapted for intelligent environment systems2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    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.

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  • 295.
    Dieckmann, Mark E
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Collisionless tangential discontinuity between pair plasma and electron–proton plasma2020In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 27, no 3, article id 032105Article in journal (Refereed)
    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.

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  • 296.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Borghesi, M.
    Queens University of Belfast, North Ireland.
    Thin-shell instability in collisionless plasma2015In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, no 3, p. 031101-Article in journal (Refereed)
    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.

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  • 297.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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 plasma2018In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 25, no 5, article id 064502Article in journal (Refereed)
    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.

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  • 298.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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 shock2018In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 473, no 1, p. 198-209Article in journal (Refereed)
    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.

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  • 299.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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 differences2018In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, no 1, article id 014014Article in journal (Refereed)
    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.

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  • 300.
    Dieckmann, Mark E
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    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 plasma2017In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 24, no 9, article id 094501Article in journal (Refereed)
    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.

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