liu.seSearch for publications in DiVA
2345 201 - 211 of 211
rss atomLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
  • Öhman, Caroline
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Freidenvall, Lovisa
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Kooperativt lärande inom matematisk problemlösning i tidiga skolår: -En litteraturstudie2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med den här litteraturstudien är att ta reda på vad forskning visar gällande användning av kooperativt lärande i matematikundervisningen vid problemlösning. Genom databassökning valdes forskningsartiklar ut som sedan granskades och analyserades. Resultatet talar för att kooperativt lärande kan främja elevers problemlösningsförmåga inom matematik. Genom att arbeta med kooperativ lärande får både lärare och elever chansen att gå djupare in på ämnet och lära av varandra. Det krävs en del ansträngning både av läraren men även av eleverna.

  • Youssef, Lovisa
    et al.
    Linköping University, Department of Management and Engineering, Economics.
    Zelic, Tijana
    Linköping University, Department of Management and Engineering, Economics.
    Information Diffusion and Safe Havens: Multi-scale Network Dynamics in the Biotech Markets2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper analyzes the return connectedness between the biotechnology sector and other financial assets for 1 January 2000 to 31 December 2018, using an empirical approach from both time- and frequency-domain. The results reveal that the connectedness between the biotechnology sector and other financial assets are decreasing with time, entailing high diversification opportunities in the long-run. Our results also suggest that the spillover effect from the biotechnology sector is higher than the spillover effect to the biotechnology sector, proposing that the sector affects other financial assets to a greater extent than they affect the biotechnology sector. Concurrently, we found that the net directional connectedness is negative for the sector, which means that it does not transmit shocks to others since it is not subject to significant return or volatility shocks. This implies that the systematic risk connected to the biotechnology sector is lower than previous studies argue for. Thus, our main finding is that investments in the sector has safe haven properties, indicating that they are independent towards other sectors. By investing in the biotechnology sector, investors contribute to society and supports the R&D, leading to development of vital drugs. In light of this, we argue that investments in the sector are socially beneficial. Building on these insights, investments in the biotechnology sector are of importance when investing in a prosperous world.

  • Sandmark, David
    Linköping University, Department of Electrical Engineering, Automatic Control.
    Navigation Strategies for Improved Positioning of Autonomous Vehicles2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report proposes three algorithms using model predictive control (MPC) in order to improve the positioning accuracy of an unmanned vehicle. The developed algorithms succeed in reducing the uncertainty in position by allowing the vehicle to deviate from a planned path, and can also handle the presence of occluding objects. To achieve this improvement, a compromise is made between following a predefined trajectory and maintaining good positioning accuracy.

    Due to the recent development of threats to systems using global navigation satellite systems to localise themselves, there is an increased need for methods of localisation that can function without relying on receiving signals from distant satellites. One example of such a system is a vehicle using a range-bearing sensor in combination with a map to localise itself. However, a system relying only on these measurements to estimate its position during a mission may get lost or gain an unacceptable level of uncertainty in its position estimates. Therefore, this thesis proposes a selection of algorithms that have been developed with the purpose of improving the positioning accuracy of such an autonomous vehicle without changing the available measurement equipment. These algorithms are:

    • A nonlinear MPC solving an optimisation problem.
    • A linear MPC using a linear approximation of the positioning uncertainty to reduce the computational complexity.
    • A nonlinear MPC using a linear approximation (henceforth called the approximate MPC) of an underlying component of the positioning uncertainty in order to reduce computational complexity while still having good performance.

    The algorithms were evaluated in two different types of simulated scenarios in MATLAB. In these simulations, the nonlinear, linear and approximate MPC algorithms reduced the root mean squared positioning error by 20-25 %, 14-18 %, and 23-27 % respectively, compared to a reference path. It was found that the approximate MPC seems to have the best performance of the three algorithms in the examined scenarios, while the linear MPC may be used in the event that this is too computationally costly. The nonlinear MPC solving the full problem is a reasonable choice only in the case when computing power is not limited, or when the approximation used in the approximate MPC is too inaccurate for the application.

  • Marres, Noortje
    et al.
    Department of Sociology, Goldsmiths, University of London, New Cross, London, UK.
    Moats, David
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Mapping Controversies with Social Media: The Case for Symmetry2015In: Social Media + Society, ISSN 2056-3051, E-ISSN 2056-3051, Vol. 1, p. 1-17Article in journal (Refereed)
    Abstract [en]

    This article assesses the usefulness for social media research of controversy analysis, an approach developed in Science and Technology Studies (STS) and related fields. We propose that this approach can help to address an important methodological problem in social media research, namely, the tension between social media as resource for social research and as an empirical object in its own right. Initially developed for analyzing interactions between science, technology, and society, controversy analysis has in recent decades been implemented digitally to study public debates and issues dynamics online. A key feature of controversy analysis as a digital method, we argue, is that it enables a symmetrical approach to the study of media-technological dynamics and issue dynamics. It allows us to pay equal attention to the ways in which a digital platform like Twitter mediates public issues, and to how controversies mediate “social media” as an object of public attention. To sketch the contours of such a symmetrical approach, the article discusses examples from a recent social media research project in which we mapped issues of “privacy” and “surveillance” in the wake of the National Security Agency (NSA) data leak by Edward Snowden in June 2013. Through a discussion of social media research practice, we then outline a symmetrical approach to analyzing controversy with social media. We conclude that the digital implementation of such an approach requires further exchanges between social media researchers and controversy analysts.

  • Moats, David
    et al.
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Nick, Seaver
    Department of Anthropology, Tufts University, Medford, USA.
    “You Social Scientists Love Mind Games”: Experimenting in the “divide” between data science and critical algorithm studies2019In: Big Data and Society, ISSN 2053-9517, E-ISSN 2053-9517, Vol. 6, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    In recent years, many qualitative sociologists, anthropologists, and social theorists have critiqued the use of algorithms and other automated processes involved in data science on both epistemological and political grounds. Yet, it has proven difficult to bring these important insights into the practice of data science itself. We suggest that part of this problem has to do with under-examined or unacknowledged assumptions about the relationship between the two fields—ideas about how data science and its critics can and should relate. Inspired by recent work in Science and Technology Studies on interventions, we attempted to stage an encounter in which practicing data scientists were asked to analyze a corpus of critical social science literature about their work, using tools of textual analysis such as co-word and topic modelling. The idea was to provoke discussion both about the content of these texts and the possible limits of such analyses. In this commentary, we reflect on the planning stages of the experiment and how responses to the exercise, from both data scientists and qualitative social scientists, revealed some of the tensions and interactions between the normative positions of the different fields. We argue for further studies which can help us understand what these interdisciplinary tensions turn on—which do not paper over them but also do not take them as given.

  • Hallgren, Erik
    et al.
    Linköping University, Department of Thematic Studies.
    Åman, Olle
    Linköping University, Department of Thematic Studies.
    Methane fluxes in lakes at different spatiotemporal scales2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Freshwater bodies such as lakes release the greenhouse gas methane (CH4) into the atmosphere. Global emissions from lakes are estimated to emit more CH4 than oceans, despite that lakes occupies a much smaller global land area. Lakes are therefore significant components for global budgets of CH4. Accurate global estimations of lakes are troublesome, partly because of the spatial and temporal variability of CH4 fluxes, making regional and global assessments filled with uncertainties. Yet, few studies consider the spatial and temporal variability of CH4 fluxes. Therefore, this study investigates the spatial and temporal variability of CH4 fluxes in lakes at different scales. Measurements were made during two field campaigns in lake Venasjön and Parsen, located in the municipality of Söderköping, Sweden. We used the commonly used floating chamber (FC) method for CH4 flux measurements. In order to investigate the small-scale flux variability, we redeveloped the FC-method by constructing two grids consisting of seven FCs distributed approximately 1m apart from each other. One grid was placed at the shallow zone at the inflow of each lake and the other at the lakes deepest zone. By sampling the grid several times every field campaign, spatial and temporal variability of fluxes at different scales could be measured. Overall, we found a significant difference of CH4 fluxes in both lakes depending on field campaign and grid location. Our results also indicate that there is a small-scale variability of CH4 fluxes in lakes. Our hope is that these findings can illustrate the importance of investigating lake fluxes at small spatial and temporal scales.

  • Nygren, Jennifer
    Linköping University, Department of Thematic Studies, Tema Environmental Change.
    Dina fantasiparker i norr: En visuell diskursanalys av svenska nationalparkers turistbroschyrer rörande områden av fjällnatur och samebyar2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This essay aims to create insight and knowledge about tourist discourses regarding nature, by examining which images and representations about nature in the Swedish national parks that are highlighted in tourist brochures, how human-nature relations are produced, but also what implications it can induce. With a delimited focus on nine national parks that meet the criteria of mountain nature or include reindeer herding Sami villages. Through a visual discourse analysis as a method, the pictures, texts, and maps of the tourist brochures have been analyzed with the application of Foucault's discourse perspective where power, knowledge, and truth are central concepts. The result of this study is that the discursive formations consist of three main features of nature. It is presented as something exotic, externally, sublime, untouched, and prehistoric, but also as an accessible and romanticized place for the tourist, and at the same time as something special for Sweden, which symbolizes its identity. The tourist is portrayed as a temporary visitor, whose relation to nature is distinguished from Sami people, who instead are presented as "natural" attractions for the tourist. All in all, this study results in a refilling of a knowledge gap regarding the presentation of representations by various practitioners about Swedish national parks, while at the same time demonstrating similar representations that previous studies have resulted in.

  • Hall, Marcus
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Forsberg, David
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Reduced Fuel Consumption of Heavy-Duty Vehicles using Pulse and Glide2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The transport sector always strive towards reduced fuel consumption for heavydutyvehicles. One promising control strategy is to use Pulse and Glide. Themethod works by acceleration to a high speed and then glide in neutral gear to alow speed.Two different control strategies and four different glide options were investigated.The two strategies were either to follow the optimal BSFC-line or using optimalcontrol. For each strategy, different velocity spans between the upper and lowervelocity were tested.The results show that the fuel consumption can be reduced up to 8.1 % comparedto a constant speed driving strategy. The fuel consumption was reduced the mostfor lower velocities and if the difference between the upper and lower velocity forthe Pulse and Glide strategy was kept small. The fuel saving can be explaineddue to increased engine efficiency during the pulse. The results also show thatthe difference between the rule-based and optimization based control strategy issmall. It can be concluded that a near-optimal strategy for a heavy-duty vehicleutilizing Pulse and Glide is to always pulse on the optimal BSFC-line.

  • Tegendal, Lukas
    Linköping University, Department of Electrical Engineering, Computer Vision.
    Watermarking in Audio using Deep Learning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Watermarking is a technique used to used to mark the ownership in media such as audio or images by embedding a watermark, e.g. copyrights information, into the media. A good watermarking method should perform this embedding without affecting the quality of the media. Recent methods for watermarking in images uses deep learning to embed and extract the watermark in the images. In this thesis, we investigate watermarking in the hearable frequencies of audio using deep learning. More specifically, we try to create a watermarking method for audio that is robust to noise in the carrier, and that allows for the extraction of the embedded watermark from the audio after being played over-the-air. The proposed method consists of two deep convolutional neural network trained end-to-end on music with simulated noise. Experiments show that the proposed method successfully creates watermarks robust to simulated noise with moderate quality reductions, but it is not robust to the real world noise introduced after playing and recording the audio over-the-air.

  • Torniainen, Kalle
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Insugstrycksreglering av turbomotoriserade dragracingmotorcyklar2019Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Vid acceleration från stillastående med en turbomotoriserad dragracingmotorcykel behöver motorcykelns insugstryck regleras. Om regleringen av insugstrycket inte lyckas uppstår en okontrollerad och hastig ökning av insugstrycket. En för hastig ökning av insugstrycket leder till att vridmomentet från motorn ökar snabbare än önskat. Konsekvenserna av en för hastig vridmomentsökning blir att motorcykelns framhjul lyfter eller att motorcykelns bakhjul tappar greppet mot banan och spinner loss. I rapporten testas, simuleras och jämförs både nya och gamla koncept för att reglera insugstrycket i startögonblicket. Konceptet som i beslutsmatrisen fick högst viktad summa visade i utförda test god förmåga att reglera insugstrycket. Konceptet med högst viktad summa var koncept A. Koncept A använder sig av mottrycket i wastegatehatten som återkoppling till styrenheten. Hårdvaran som används i koncept A är en pneumatisk wastegate-ventil med två solenoider.

  • Kupreyeva, Aliaksandra
    Linköping University, Department of Mathematics.
    Simplices of f-vectors2019Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In this thesis the properties of the convex hulls of the sets of f-vectors of simplicial complexes on p vertices are investigated. The work is primarily constrained to the convex hulls of the sets of f-vectors of simplicial complexes of dimension at most 2 and 3. We study the functions which count the number of lattice points in these convex hulls and in their integral dilations. Also, the center of mass for these sets of f-vectors is studied. For the convex hulls of the sets of f-vectors with cardinality at most 3 we also investigate whether there is a compact rational function representing its f-vectors. Chapter 6 is devoted to researching whether there is any relationship between the number of f-vectors and the total number of lattice points in the convex hulls of the sets f-vectors with cardinality at most n.