liu.seSearch for publications in DiVA
Change search
Refine search result
12 1 - 50 of 68
CiteExportLink 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
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abdulla, Ariyan
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Andersson, Erik
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Heuristiska algoritmer för schemaläggning i real-tidssystem med hänsyn till data beroenden2018Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The schedule for the jobs in a real-time system can have a huge impact on how the system behave. Since real-time systems are common in safety applications it is important that the scheduling is done in a valid way. Furthermore, one can enhance the performance of the applications by minimizing data latency and jitter. A challenge is that jobs in real-time systems usually have complex constraints making it too time consuming to minimize data latency and jitter to optimality. The purpose of this report is to investigate the possibility of creating high quality schedules using heuristics, with the goal to keep the computational time under one minute. This will be done by comparing three different algorithms that will be used on real scheduling instances provided by the company Arcticus. The first algorithm is a greedy heuristic, the second one a local search and the third one is a metaheuristic, simulated annealing. The results indicate that the data latency can be reduced whilst keeping the computational time below one minute.

  • 2.
    Abrahamsson, Olle
    Linköping University, Department of Electrical Engineering, Communication Systems.
    Hide and Seek in a Social Network2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a known heuristic for decreasing a node's centrality scores while maintaining influence, called ROAM, is compared to a modified version specifically designed to decrease eigenvector centrality. The performances of these heuristics are also tested against the Shapley values of a cooperative game played over the considered network, where the game is such that influential nodes receive higher Shapley values. The modified heuristic performed at least as good as the original ROAM, and in some instances even better (especially when the terrorist network behind the World Trade Center attacks was considered). Both heuristics increased the influence score for a given targeted node when applied consecutively on the WTC network, and consequently the Shapley values increased as well. Therefore the Shapley value of the game considered in this thesis seems to be well suited for discovering individuals that are assumed to actively trying to evade social network analysis.

  • 3.
    Asadzadeh, Mohammad
    et al.
    Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg.
    Bartoszek, Krzysztof
    Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg.
    A combined discontinuous Galerkin and finite volume scheme for multi–dimensional VPFP system2011In: AIP Conference Proceedings 1333 / [ed] Deborah A. Levin, Ingrid J. Wysong, Alejandro L. Garcia and Henry Abarbanel, American Institute of Physics (AIP), 2011, Vol. 1333, p. 57-62Conference paper (Refereed)
    Abstract [en]

    We construct a numerical scheme for the multi-dimensional Vlasov-Poisson-Fokker-Planck system based on a combined finite volume (FV) method for the Poisson equation in spatial domain and the streamline diffusion (SD) and discontinuous Galerkin (DG) finite element in time, phase-space variables for the Vlasov-Fokker-Planck equation.

  • 4.
    Balck, Lovisa
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Bogren Jaldestam, Frida
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Läxans vara eller icke vara i matematikundervisningen.: Påverkas elevers prestation och motivation av matematikläxor?2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna systematiska litteraturstudie har varit att se hur forskare ser på läxan i allmänhet och i synnerhet matematikläxan. Med ett fokus på vilka olika typer av läxor det finns både i allmänhet men även inom matematikämnet. Fokus har även legat på hur läxor i matematik påverkar elevers motivation och prestation i matematikämnet.  Studien består av tolv artiklar och rapporter som använts för att besvara frågeställningarna. Vi har fokuserat på studier gjorda på elever i årskurs 4-6, men har använt artiklar och rapporter som diskuterar andra årskurser om resultaten kunnat generaliseras till andra årskurser. Begrepp som använts har varit matematik, läxa, motivation och prestation.  Resultatet visar att det finns många typer av matematikläxor som har olika betydelse för elevers motivation och prestation. Forskarna är inte eniga om något enhetligt svar på om matematikläxor påverkar elevers motivation och prestationer inom matematik. Flertalet av forskarna ser dock positivt på matematikläxan och anser att den påverkar elevers prestation till det bättre. Inom motivation är forskarna överrens om att läxor påverkar elevers motivation, det råder dock skilda åsikter om läxorna påverkar elevers motivation positivt eller negativt.

  • 5.
    Bartoszek, Krzysztof
    Gdansk University of Technology, Poland.
    A Graph – String Model of Gene Assembly in Ciliates [Grafowo-tekstowy model rekombinacji DNA u orzęsek]2006In: Zeszyty Naukowe Wydzialu ETI Politechniki Gdanskiej, 2006, p. 521-534Conference paper (Refereed)
    Abstract [en]

    The ciliates are a family of unicellular organisms that characterize themselves by having two types of nuclei, micro - and macronuclei. During cell mating the genetic material must change from the micronuclei to the macronuclei form. The paper summarises a formal model for this change. The model, which is described in recent works, is based on strings and graphs. It shows that inside the cell complex computational operations have to take place.

  • 6.
    Bartoszek, Krzysztof
    et al.
    Department of Mathematics, Gdansk University of Technology, Gdansk, Poland.
    Signerska, Justyna
    Department of Mathematics, Gdansk University of Technology, Gdansk, Poland.
    The Fundamental Group, Covering Spaces and Topology in Biology2006In: Conference materials 9th International Workshop for Young Mathematicians "Topology", 2006, p. 19-29Conference paper (Other academic)
    Abstract [en]

    Abstract. We give a short introduction to homotopy theory. We pass to the concepts of a pointed space (X, x0), the fundamental group of X, a simply connected space (with the example of the space contractible to a point), introduce basic concepts of covering spaces (e.g. covering map/space, fiber over x, Path lifting Theorem). With the use of the exponential map and the idea of the index of a loop, we show that the fundamental group of the circle S1 is isomorphic to the integers Z with addition. We mention some other interesting fundamental groups (e.g. the fundamental group of a torus or of thefigure eight). We also present some very interesting applications of topological concepts in Molecular Biology.

  • 7.
    Bennevall, Marcus
    Linköping University, Department of Mathematics.
    Creativity in Mathematics Curricula – An International Comparison between Singapore, Hong Kong, Sweden, and Norway2017Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Studies have shown that creative mathematically founded reasoning (CMR) outperforms algorithmic reasoning (AR) in regards to retention and (re)construction of knowledge. This suggests that creativity should be encouraged in national high-school mathematics curricula. The aim of the present study is to compare how creativity is framed in different national high-school mathematics curricula, using the following definition: creativity is the characteristics of people, processes, and environments which lead to new and original products that are useful or otherwise attractive to an individual or a society. Utilizing content and discourse analysis, the present study thus contrasts how the high-school mathematics curricula of Singapore, Hong Kong, Sweden, and Norway handle and value creativity, and also examines which role creativity takes in each curricula.

    Findings suggest that Singapore’s curriculum emphasizes creativity the most, and frequently does so in relation to assessment. Hong Kong’s curriculum is found to emphasize creativity in diverse ways, often using words with connotations to playfulness. Analysis of Sweden’s curriculum indicates a relatively minute focus on creativity, tending to put it in a teacher-centered context. A feature of Norway’s curriculum is an increasing emphasis on creativity as courses approach tertiary education. This also suggests a rising value of creativity in its curriculum. A similar though not as pronounced trajectory is found also in Singapore’s curriculum. In the Asian and Norwegian curricula, creativity is expressed both as a means and an end, while in Sweden’s curriculum it is only seen as an end.

    The results are discussed in terms of potential reasons for the prominent national features, and the study also includes an evaluation of the aptness of the suggested definition of creativity, a review of the limitations of the study, as well as propositions for further research. Finally, two recommendations are given to the National Agency for Education in Sweden – Skolverket – based on the results of the study: 1) diversify the emphasis on creativity in the curriculum, and 2) ensure alignment between what teachers value and what Skolverket values with respect to creativity.

  • 8.
    Bergman Ärlebäck, Jonas
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Doerr, Helen M.
    Syracuse University.
    At the core of modelling: Connecting, coordinating and integrating models2015In: Proceedings of the 9th Congress of European Research in Mathematics Education / [ed] K. Krainer & N. Vondrová, 2015, p. 802-808Conference paper (Refereed)
    Abstract [en]

    This theoretical paper introduces the notions of connecting, coordinating and integrating models to analyse and reflect on how models are created and developed. We define, discuss and apply these constructs to some theoretical perspectives in the present modelling discourse. We draw on an example from a model application activity within a model development sequence to illustrate these constructs. Our hope is to spark a discussion that will enhance our understanding about the nature of mathematical modelling and the teaching and learning of, and through, modelling.

  • 9.
    Böörs, Mikael
    et al.
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, Faculty of Science & Engineering.
    Wängberg, Tobias
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, Faculty of Science & Engineering.
    Classification by Decomposition: A Partitioning of the Space of 2X2 Symmetric Games2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Game theory is the study of strategic interaction between rational agents. The need for understanding interaction arises in many different fields, such as: economics, psychology, philosophy, computer science and biology. The purpose of game theory is to analyse the outcomes and strategies of these interactions, in mathematical models called games. Some of these games have stood out from the rest, e.g. Prisoner's Dilemma, Chicken and Stag Hunt. These games, commonly referred to as the standard games, have attracted interest from many fields of research. In order to understand why these games are interesting and how they differ from each other and other games, many have attempted to sort games into interestingly different classes. In this thesis some already existing classifications are reviewed based on their mathematical structure and how well justified they are. Emphasis is put on mathematical simplicity because it makes the classification more generalisable to larger game spaces. From this review we conclude that none of the classifications captures both of these aspects. We therefore propose a classification of symmetric 2x2 games based on decomposition. We show that our proposed method captures everything that the previous classifications caputure. Our method arguably explains the interesting differences between the games, and we justify this claim by computer experiments. Moreover it has a simple mathematical structure. We also provide some results concerning the size of different game spaces.

  • 10.
    Duits, R.
    et al.
    Eindhoven University of Technology, Netherlands.
    Ghosh, Arpan
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Dela Haije, T. C. J.
    Eindhoven University of Technology, Netherlands.
    Mashtakov, A.
    Eindhoven University of Technology, Netherlands.
    On Sub-Riemannian Geodesics in SE(3) Whose Spatial Projections do not Have Cusps2016In: Journal of dynamical and control systems, ISSN 1079-2724, E-ISSN 1573-8698, Vol. 22, no 4, p. 771-805Article in journal (Refereed)
    Abstract [en]

    We consider the problem P (c u r v e) of minimizing for a curve x in with fixed boundary points and directions. Here, the total length Laeyen0 is free, s denotes the arclength parameter, kappa denotes the absolute curvature of x, and xi amp;gt; 0 is constant. We lift problem P (c u r v e) on to a sub-Riemannian problem P (m e c) on SE(3)/({0}xSO(2)). Here, for admissible boundary conditions, the spatial projections of sub-Riemannian geodesics do not exhibit cusps and they solve problem P (c u r v e) . We apply the Pontryagin Maximum Principle (PMP) and prove Liouville integrability of the Hamiltonian system. We derive explicit analytic formulas for such sub-Riemannian geodesics, relying on the co-adjoint orbit structure, an underlying Cartan connection, and the matrix representation of SE(3) arising in the Cartan-matrix. These formulas allow us to extract geometrical properties of the sub-Riemannian geodesics with cuspless projection, such as planarity conditions, explicit bounds on their torsion, and their symmetries. Furthermore, they allow us to parameterize all admissible boundary conditions reachable by geodesics with cuspless spatial projection. Such projections lay in the upper half space. We prove this for most cases, and the rest is checked numerically. Finally, we employ the formulas to numerically solve the boundary value problem, and visualize the set of admissible boundary conditions.

  • 11.
    Ekblom, Jonas
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, Faculty of Science & Engineering.
    Decision Making under Uncertainty in Financial Markets: Improving Decisions with Stochastic Optimization2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses the topic of decision making under uncertainty, with particular focus on financial markets. The aim of this research is to support improved decisions in practice, and related to this, to advance our understanding of financial markets. Stochastic optimization provides the tools to determine optimal decisions in uncertain environments, and the optimality conditions of these models produce insights into how financial markets work. To be more concrete, a great deal of financial theory is based on optimality conditions derived from stochastic optimization models. Therefore, an important part of the development of financial theory is to study stochastic optimization models that step-by-step better capture the essence of reality. This is the motivation behind the focus of this thesis, which is to study methods that in relation to prevailing models that underlie financial theory allow additional real-world complexities to be properly modeled.

    The overall purpose of this thesis is to develop and evaluate stochastic optimization models that support improved decisions under uncertainty on financial markets. The research into stochastic optimization in financial literature has traditionally focused on problem formulations that allow closed-form or `exact' numerical solutions; typically through the application of dynamic programming or optimal control. The focus in this thesis is on two other optimization methods, namely stochastic programming and approximate dynamic programming, which open up opportunities to study new classes of financial problems. More specifically, these optimization methods allow additional and important aspects of many real-world problems to be captured.

    This thesis contributes with several insights that are relevant for both financial and stochastic optimization literature. First, we show that the modeling of several real-world aspects traditionally not considered in the literature are important components in a model which supports corporate hedging decisions. Specifically, we document the importance of modeling term premia, a rich asset universe and transaction costs. Secondly, we provide two methodological contributions to the stochastic programming literature by: (i) highlighting the challenges of realizing improved decisions through more stages in stochastic programming models; and (ii) developing an importance sampling method that can be used to produce high solution quality with few scenarios. Finally, we design an approximate dynamic programming model that gives close to optimal solutions to the classic, and thus far unsolved, portfolio choice problem with constant relative risk aversion preferences and transaction costs, given many risky assets and a large number of time periods.

    List of papers
    1. Corporate Hedging: an answer to the "how" question
    Open this publication in new window or tab >>Corporate Hedging: an answer to the "how" question
    2018 (English)In: Annals of Operations Research, ISSN 0254-5330, E-ISSN 1572-9338, Vol. 266, no 1-2, p. 35-69Article in journal (Refereed) Published
    Abstract [en]

    We develop a stochastic programming framework for hedging currency and interest rate risk, with market traded currency forward contracts and interest rate swaps, in an environment with uncertain cash flows. The framework captures the skewness and kurtosis in exchange rates, transaction costs, the systematic risks in interest rates, and most importantly, the term premia which determine the expected cost of different hedging instruments. Given three commonly used objective functions: variance, expected shortfall, and mean log profits, we study properties of the optimal hedge. We find that the choice of objective function can have a substantial effect on the resulting hedge in terms of the portfolio composition, the resulting risk and the hedging cost. Further, we find that unless the objective is indifferent to hedging costs, term premia in the different markets, along with transaction costs, are fundamental determinants of the optimal hedge. Our results also show that to reduce risk properly and to keep hedging costs low, a rich-enough universe of hedging instruments is critical. Through out-of-sample testing we validate the findings of the in-sample analysis, and importantly, we show that the model is robust enough to be used on real market data. The proposed framework offers great flexibility regarding the distributional assumptions of the underlying risk factors and the types of hedging instruments which can be included in the optimization model.

    Place, publisher, year, edition, pages
    New York, United States: Springer-Verlag New York, 2018
    Keywords
    Stochastic programming, Currency hedging, Term premia, Uncertain cash flows, Risk management
    National Category
    Economics
    Identifiers
    urn:nbn:se:liu:diva-142117 (URN)10.1007/s10479-017-2645-6 (DOI)000433953200003 ()2-s2.0-85032818917 (Scopus ID)
    Available from: 2017-10-23 Created: 2017-10-23 Last updated: 2018-10-05Bibliographically approved
  • 12.
    Ekström, Gustaf
    et al.
    Linköping University, Department of Mathematics. Linköping University, Faculty of Science & Engineering.
    Emanuelsson, Jakob
    Linköping University, Department of Mathematics. Linköping University, Faculty of Science & Engineering.
    Gymnasieelevers matematiska svårigheter vid hantering och lösning av andragradsekvationer: En systematisk litteraturstudie2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie är en systematisk litteraturstudie som syftar till att undersöka vilka matematiska svårigheter elever på gymnasiet har med andragradsekvationer. I aktuell forskning identifieras olika svårigheter som elever har med ämnet och struktureras i olika kategorier som presenteras i resultatet. Studien resultat visar att elever har flera olika algebraiska brister när de ska hantera andragradsekvationer vilket medför att de gör flera enkla fel. Exempelvis har elever svårt med vad en obekant är och vet inte vad en ekvation är. Elever har även stora svårigheter med förståelsen av andragradsekvationer. Elever kan ofta inte definiera vad en andragradsekvation är utan blandar ofta ihop det med en förstagradsekvation. I studien framgår även att många elever endast ser området andragradsekvationer som en rad formler och symboler som de ska lära sig utantill utan något sammanhang. Elever tenderar även att endast använda sig av en lösningsmetod när de ska lösa andragradsekvationer och väljer därmed inte alltid den lämpligaste metoden. Dessutom har elever svårt att lösa andragradsekvationer som inte är skriva på standardform. Dessa svårigheter beror antagligen på flera faktorer och det behövs mer forskning inom området. Orsakerna till svårigheterna eleverna har är dock inget som berörs i denna studie. Studien ger en inblick i vilka svårigheter elever har kring ämnet och ger förhoppningsvis lärare stöd vid utformning av undervisning om andragradsekvationer. 

  • 13.
    Elebring, Viktoria
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Laborativ matematik: ett sätt att väcka nyfikenhet och lust att lära?2012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie behandlar arbetet av laborativ matematik för grundskolans senare år. Enligt läroplanen och kursplanen är undervisningens syfte att utveckla elevers kunskaper om matematikens användning både i vardagliga situationer och inom andra ämnesområden. Undervisningen ska även bidra till att elever kan reflektera över matematikens användning i vardagslivet. Många elever är idag omotiverade, uttråkade och har tappat lusten för att lära, vilket kan bero på att lärobokstyrd undervisning domineras i grundskolans senare år. Studien är ett konsumtionsinriktat arbete med litteraturstudie som metod. Databaserna som användes var Academic Search Primer och ERIC. Resultatet visade att om laborativt material används i undervisningen bidrar det till att arbetssättet varieras. Då får eleverna större möjlighet att arbeta tillsammans i grupp, diskutera matematiska begrepp och idéer och uttrycka sitt matematiska tänkande. Syftet med laborativ matematik är att hjälpa eleverna att koppla samman det konkreta materialet med abstrakta begrepp, där läraren har en avgörande roll. Det laborativa materialet i sig hjälper inte eleverna till en ökad förståelse, utan det krävs god planering och reflektion över arbetet för att syftet ska uppnås. Elevers lust och motivation hänger ihop med elevers förståelse för matematik. På detta sett kan laborativ matematik bidra till att elevers intresse för ämnet ökar.

  • 14.
    Engberg, Lovisa
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Analys och optimering av godsflöden i Linköpings city2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Urbanization and city expansion result in an increasing need of transportation of goods, and in order to maintain efficiency, measures are needed. The aim of city logistics is to minimize negative impacts associated with city center goods distribution, such as traffic congestion and negative impacts on the living environment.

    Several city logistic measures have previously been suggested, such as freight consolidation, governance and advanced IT systems. Within the SAMLIC project started in 2004, a demonstration project known as PILOT was carried out in central Linköping, wherein the concept of freight consolidation was applied in reality. The objective was to evaluate the economic potential of freight consolidation.

    The aim of this thesis was to formulate mathematical models of the distribution of goods in a medium sized Swedish city. The models are to be used in the evaluation of city logistic measures, focusing on freight consolidation.

    The distribution problem is modelled as a vehicle routing problem, and methods for solving the resulting optimization problems have been implemented. Using data from PILOT, the models have been applied on Linköping with the purpose of evaluating the methods, as well as investigating the potential of using models for planning the distribution of goods.

    Conclusions involve that analyses of, and comparisons between, city lo-gistic measures can be efficiently made using mathematical models. The case study also indicates that goods distribution can be improved through the use of optimization methods, which further motivates mathematical modelling.

  • 15.
    Frejd, Peter
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Bergsten, Christer
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Mathematical modelling as a professional task2016In: Educational Studies in Mathematics, ISSN 0013-1954, E-ISSN 1573-0816, Vol. 91, no 1, p. 11-35Article in journal (Refereed)
    Abstract [en]

    Educational research literature on mathematical modelling is extensive. However, not much attention has been paid to empirical investigations of its scholarly knowledge from the perspective of didactic transposition processes. This paper reports from an interview study of mathematical modelling activities involving nine professional model constructors. The research question was: How can mathematical modelling by professional mathematical model constructors be characterised? The analysis of our interview data inspired by the coding procedure of grounded theory led us to the description of three main types of modelling activities as a characterisation of mathematical modelling as a professional task. In data-generated modelling the models are developed principally from quantitative data drawing on no or only some assumed knowledge of the system being modelled, while in theory-generated modelling the models are developed based on established theory. In the third activity, model-generated modelling, the development of new models is based on already established models. For all types, the use of computer support and communication between clients, constructors and other experts are central aspects. Finally, the three types of modelling activities are related to existing theoretical descriptions of mathematical modelling and the relevance of the study for mathematical modelling in education is discussed.

  • 16.
    Frenell, Miranda
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Widén, Mathilda
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Artikelplacering i lager: Simulering med Arena2018Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Case studies demonstrate that substantial benefits can be achieved by appropriately designing and operating a warehouse. Studies using both analytical models and simulations have additionally confirmed that significant reductions in travel time can be obtained from dedicated storage. But applying academic research results to real problems does not always lead to the best solution. This thesis examines if dedicated storage can be more efficient than storage based on class for a company, that wants to be anonymous. The existing class-based storage is compared with dedicated storage in hopes of reducing the time for sorting and order-picking two selected articles. In this paper Arena simulation models have been created to compare the total working hours for the two different layouts. The working time using the current layout is compared with an alternative layout where the two products are stored based on their characteristics rather than the article’s final destination (the customer’s location). The results indicate that the alternative layout is more efficient than the current layout. In addition, the layout using dedicated storage is, based on the simulation models, statistically better for one of the products. However, using dedicated storage does not lead to the20-25% of savings the company was hoping for, compared to using the current layout. Therefore, the company is not recommended to change to the alternative layout. The most time-consuming process in the sorting of products turned out to be the time of unloading articles from their pallets. Therefore, the company rather should focus on how to reduce the time of unloading articles, than trying to find ways to reduce the travel time in the warehouse.

  • 17.
    Hammar Chiriac, Eva
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
    Group work is not one, but a great many processes – Understanding group work dynamics2012In: Encyclopedia of Mathematics Research / [ed] Joshua D Mathias; Sophia I Cleaves, New York: Nova Science Publishers, Inc , 2012, p. 153-167Chapter in book (Other academic)
    Abstract [en]

    This book discusses current research developments in the field of mathematics. Topics presented include exceptional groups, symmetric spaces and applications; LIE group analysis; graph groupoids and corresponding representations; fuzzy logic in molecular computing; closed-loop optimal fuzzy reasoning; nozzle design optimisation; a branch-and-price algorithm for the stochastic generalised assignment problem; parametric dual regularisation in a linear-convex mathematical programming and fast multilevel algorithms for diverse application in computational biology and bioinformatics.

  • 18.
    Hansson, Eva-Maria
    Linköping University, Department of Clinical and Experimental Medicine.
    Towards a mechanistic explanation of insulin resistance, which incorporates mTOR, autophagy, and mitochondrial dysfunction2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Type 2 diabetes is a global disease which affects an increasing number of peopleevery year. At the heart of the disease lies insulin resistance in the target tissues,primarily fat and muscle. The insulin resistance is caused by the failure of a complexsignalling network, and several mechanistic hypotheses for this failure havebeen proposed. Herein, we evaluate a hypothesis that revolves around the proteinmammalian target of rapamycin (mTOR) and its feedback signals to insulin receptorsubstrate-1 (IRS1). In particular, we have re-examined this hypothesis andrelevant biological data using a mathematical modelling approach.

    During the course of modelling we gained several important insights. For instance,the model was unable to reproduce the relation between the EC50-valuesin the dose-response curves for IRS1 and its serine residue 312 (Ser-312). Thisimplies that the presented hypothesis, where the phosphorylation of Ser-312 liesdownstream of the tyrosine phosphorylation of IRS1, is inconsistent with the provideddata, and that the hypothesis or the data might be incorrect. Similarly, wealso realized that in order to fully account for the information in the dose-responsedata, time curves needed to be incorporated into the model.

    A preliminary model is presented, which explains most of the data-sets, butstill is unable to describe all the details in the data. The originally proposed hypothesisas an explanation to the given data has been revised, and our analysisserves to exemplify that an evaluation of a mechanistic hypothesis by mere biochemicalreasoning often misses out on important details, and/or leads to incorrectconclusions. A model-based approach, on the other hand, can efficiently pin-pointsuch weaknesses, and if combined with a comprehensive understanding of biologicalvariation and generation of experimental data, mathematical modelling canprove to be a method of great potential in the search for mechanistic explanationsto the cause of insulin resistance in type 2 diabetics.

  • 19.
    Hedman, Anders
    et al.
    Linköping University, Department of Mathematics.
    von Schéele, Andreas
    Linköping University, Department of Mathematics.
    Schack och Matematik: En litteraturstudie om möjliga kopplingar mellan schackspelande och matematiklärande2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Schacket har sitt ursprung i Indien på 500-talet. Spelets karaktär har fascinerat människan genom tiderna. Mångamatematiker har analyserat spelet samt utvecklat problem knutna till det. I detta examensarbete analyserar vi destudier som undersökt om det finns en koppling mellan schackspelande och matematiklärande. Vi har ävenanalyserat studier som har undersökt om det finns en koppling mellan schackspelande och lärande i andraskolämnen. Det visar sig att det inte gjorts så många vetenskapliga studier för att undersöka dessa kopplingar. Deflesta av de studier som genomförts kvalificeras som kvasistudier. Flera studier visar att det inte finns någon tydligkoppling mellan schackspelande och matematiklärande. I vår litteraturstudie kan vi inte se att denna koppling finns,men vi anar dock att den finns. Vi hoppas att det i framtiden genomförs mer vetenskaplig forskning inom området.

  • 20.
    Hjelmberg, David
    et al.
    Linköping University, Department of Management and Engineering, Production Economics.
    Lagerström, Björn
    Linköping University, Department of Management and Engineering, Production Economics.
    Pricing of American options with discrete dividends using a PDE and a volatility surface while calculating derivatives with automatic differentiation2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis we have examined the possibility of pricing multiple American options, on an underlying asset with discrete dividends, with a finite difference method. We have found a good and stable way to price one American option by solving the BSM PDE backwards, while also calculating the Greeks of the option with automatic differentiation. The list of Greeks for an option is quite extensive since we have been using a local volatility surface.

    We have also tried to find a way to price several American options simultaneously by solving a forward PDE. Unfortunately, we haven't found any previous work that we could use with our local volatility surface, while still keeping down the computational time. The closest we got was to calculate the value of a compound option in a forward mode, but in order to use this to value an American option, we needed to go through an iterative process which calculated a forward or backward European PDE in every step.

  • 21.
    Holm, Åsa
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    A Tailored Branch-and-Bound Method for Optimizing the Dwelling Time Pattern and Catheter Positioning in HDR Brachytherapy2013Report (Other academic)
    Abstract [en]

    High dose-rate (HDR) brachytherapy is one type of treatment for prostate cancer, in which a radioactive source is moved through catheters implanted into the prostate. For each patient, a unique treatment plan is constructed. This plan determines for example the catheter positioning and the dwelling time pattern, that is, where and for how long the source should stop.

    Mathematical optimization methods are frequently used to find high-quality dwelling time patterns. However, choosing the catheter positioning is usually done without any aid of mathematical optimization methods. Researchers have recently suggested some optimization models for catheter positioning, and also heuristics for solving them. However, there are no available methods for finding the optimal solution of these models within a clinically acceptable time frame.

    In this paper we present the foundation for a branch-and-bound method that has been tailored to the catheter positioning problem. Tests show that this tailored branch-and-bound method has some promising features, for example that the dual bound is improved faster than when using a standard branch-and-bound method. But the tests also show that further research is required to develop it into a method that can find the optimal solution fast enough.

  • 22.
    Holmberg, Agnes
    Linköping University, Department of Mathematics.
    Integrering av matematikhistoria i matematikundervisningen – En litteraturstudie om för- och nackdelar samt metoder för genomförandet.2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Både ämnesplanen för matematik i svensk gymnasieskola samt det centrala innehållet för samtliga gymnasiala matematikkurser framhåller att matematiken har en flertusenårig historia och att matematikundervisningen ska knyta an till matematikens historiska utveckling och betydelse. Det är tydligt att matematikhistoria ska integreras i matematikundervisningen men det finns indikationepå att matematikundervisningen i svensk skola idag har få eller inga inslag av matematikhistoria trots att detta anges som ett centralt innehåll. Denna litteraturstudie syftar till att undersöka vilka argument som forskningen funnit för respektive mot en integrering av matematikhistoria i matematikundervisningen samt hur en sådan integrering kan genomföras. Dessutom redogör litteraturstudien för vad lärare och lärarstudenter funnits ha för uppfattningar om matematikhistorians roll och funktion som en del av matematikundervisningen.

    Studien visar att en integrering av matematikhistoria i matematikundervisningen är fördelaktig utifrån flera olika aspekter. Matematikhistoria kan t.ex. bidra till att förändra elevernas syn på matematik och ge matematiken nytt liv genom att eleverna blir varse om att de historiskt kända matematikerna också har tvivlat och misslyckats i sitt utövande av matematik, vilket kan stärka elevernas självtroende. Matematikhistoria kan även bidra till att förse lärare med verktyg för att upptäcka eventuella svårigheter hos eleverna. Studien visar också att lärare och lärarstudenter överlag är positivt inställda till en integrering men uttrycker att de i stor utsträckning medvetet avstår från att använda matematikhistoria i sin undervisning på grund av brist på tid, material, kunskaper om matematikhistoria samt att de inte vet hur de ska gå tillväga för att genomföra en sådan integrering.

  • 23.
    Holmberg, Kaj
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Optimization of OSPF Routing in IP Networks2010In: Graphs and Algorithms in Communication Networks: Studies in Broadband, Optical, Wireless and Ad Hoc Networks / [ed] A. Koster and X. Munoz, Springer Berlin/Heidelberg, 2010Chapter in book (Refereed)
    Abstract [en]

    Algorithmic discrete mathematics plays a key role in the development of information and communication technologies, and methods that arise in computer science, mathematics and operations research – in particular in algorithms, computational complexity, distributed computing and optimization – are vital to modern services such as mobile telephony, online banking and VoIP. This book examines communication networking from a mathematical viewpoint. The contributing authors took part in the European COST action 293 – a four-year program of multidisciplinary research on this subject. In this book they offer introductory overviews and state-of-the-art assessments of current and future research in the fields of broadband, optical, wireless and ad hoc networks. Particular topics of interest are design, optimization, robustness and energy consumption. The book will be of interest to graduate students, researchers and practitioners in the areas of networking, theoretical computer science, operations research, distributed computing and mathematics.

  • 24.
    Holmberg, Kaj
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Call, Mikael
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Complexity of Inverse Shortest Path Routing2011In: Network Optimization: 5th International Conference, INOC 2011 / [ed] J. Pahl, T. Reiners, and S. Voß, Springer Berlin/Heidelberg, 2011, p. 339-353Chapter in book (Refereed)
    Abstract [en]

    The inverse shortest path routing problem is to decide if a set of tentative routing patterns is simultaneously realizable. A routing pattern is defined by its destination and two arc subsets of required shortest path arcs and prohibited non-shortest path arcs. A set of tentative routing patterns is simultaneously realizable if there is a cost vector such that for all routing patterns it holds that all shortest path arcs are in some shortest path and no non-shortest path arc is in any shortest path to the destination of the routing pattern. Our main result is that this problem is NP-complete, contrary to what has been claimed earlier in the literature. Inverse shortest path routing problems naturally arise as a subproblem in bilevel programs where the lower level consists of shortest path problems. Prominent applications that fit into this framework include traffic engineering in IP networks using OSPF or IS-IS and in Stackelberg network pricing games. In this paper we focus on the common subproblem that arises if the bilevel program is linearized and solved by branch-and-cut. Then, it must repeatedly be decided if a set of tentative routing patterns is realizable. In particular, an NP-completeness proof for this problem is given.

  • 25.
    Jansson, Fredrik
    Linköping University, The Institute for Analytical Sociology, IAS. Linköping University, Faculty of Arts and Sciences. Centrum för evolutionär kulturforskning, Stockholms universitet; Centre for the Study of Cultural Evolution, Stockholm University.
    What Games Support the Evolution of an Ingroup Bias?2015In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 373, p. 100-110Article in journal (Refereed)
    Abstract [en]

    There is an increasing wealth of models trying to explain the evolution of group discrimination and an ingroup bias. This paper sets out to systematically investigate the most fundamental assumption in these models: in what kind of situations do the interactions take place? What strategic structures – games – support the evolution of an ingroup bias? More specifically, the aim here is to find the prerequisites for when a bias also with respect to minimal groups – arbitrarily defined groups void of group-specific qualities – is selected for, and which cannot be ascribed to kin selection.

    Through analyses and simulations of minimal models of two-person games, this paper indicates that only some games are conducive to the evolution of ingroup favouritism. In particular, this class does not contain the prisoners' dilemma, but it does contain anti-co-ordination and co-ordination games. Contrasting to the prisoners' dilemma, these are games where it is not a matter of whether to behave altruistically, but rather one of predicting what the other person will be doing, and where I would benefit from you knowing my intentions.

    In anti-co-ordination games, on average, not only will agents discriminate between groups, but also in such a way that their choices maximise the sum of the available payoffs towards the ingroup more often than towards the outgroup. And in co-ordination games, even if agents do manage to co-ordinate with the whole population, they are more likely to co-ordinate on the socially optimal equilibrium within their group. Simulations show that this occurs most often in games where there is a component of risk-taking, and thus trust, involved. A typical such game is the stag hunt or assurance game.

  • 26.
    Jansson, Fredrik
    et al.
    Linköping University, The Institute for Analytical Sociology, IAS. Linköping University, Faculty of Arts and Sciences.
    Parkvall, Mikael
    Institutionen för lingvistik, Stockholms universitet.
    Strimling, Pontus
    Linköping University, The Institute for Analytical Sociology, IAS. Linköping University, Faculty of Arts and Sciences.
    Modeling the Evolution of Creoles2015In: Language Dynamics and Change, ISSN 2210-5824, E-ISSN 2210-5832, Vol. 5, no 1, p. 1-51Article in journal (Refereed)
    Abstract [en]

    Various theories have been proposed regarding the origin of creole languages. Describing a process where only the end result is documented involves several methodological difficulties. In this paper we try to address some of the issues by using a novel mathematical model together with detailed empirical data on the origin and structure of Mauritian Creole. Our main focus is on whether Mauritian Creole may have originated only from a mutual desire to communicate, without a target language or prestige bias. Our conclusions are affirmative. With a confirmation bias towards learning from successful communication, the model predicts Mauritian Creole better than any of the input languages, including the lexifier French, thus providing a compelling and specific hypothetical model of how creoles emerge. The results also show that it may be possible for a creole to develop quickly after first contact, and that it was created mostly from material found in the input languages, but without inheriting their morphology.

  • 27.
    Johansson, Malin
    Linköping University, Department of Culture and Communication.
    Matematikundervisning utomhus: Varför/varför inte undervisa utomhus?2015Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Jag har i detta examensarbete undersökt om matematiklärare i årskurserna 1-6 undervisar i matematik utomhus. Genom denna underökning behandlas även frågan om varför matematiklärare väljer att undervisa i matematik utomhus och varför en del matematiklärare väljer att inte undervisa i matematik utomhus. Syftet med denna underökning är att få en bild över om utemiljön används i matematikundervisningen och orsakerna till varför respektive varför inte den används. Undersökningen är en kvantitativ studie och datainsamlingen har samlats in genom en webbenkät och det samlades in 375 helt besvarade enkäter.

    Resultatet av undersökningen visar att ungefär hälften av matematiklärarna undervisar i matematik utomhus medan den andra hälften inte gör det just nu.

    Att ungefär hälften av matematiklärarna väljer att undervisa i matematik utomhus uppger dem beror på att denna undervisningsform hjälper till att fånga upp fler elever, att eleverna får använda alla sina sinnen i arbetet med matematiken och att kunskapen då förankras på ett bättre sätt. Andra orsaker till varför man som lärare väljer att undervisa i matematik utomhus är att undervisningen konkretiseras, matematikförståelsen ökar hos eleverna, det matematiska språket lyfts på ett annat sätt mellan eleverna, engagemanget ökar hos eleverna, problemlösningsuppgifter blir lättare att förklara som lärare och eleverna får lättare för att lösa dem. Matematik utomhus ger variation i undervisningen och samarbetet mellan eleverna hamnar mer i fokus.

    Den andra hälften som väljer att inte undervisa i mattematik utomhus uppger att detta beror på att det kräver mycket planering, vädret är svårt att förutspå, tiden räcker inte till för både planering och genomförandet av undervisningen samt att denna undervisningsform inte fungerar med alla elevgrupper. Andra orsaker som gör att man som lärare väljer att inte undervisa i matematik utomhus är att lärarna saknar den kunskap som behövs för att kunna undervisa utomhus, resurserna räcker inte till, bra material saknas, eleverna gillar att jobba i matematikboken och tycker att undervisning utomhus är tråkigt och jobbigt samt att utemiljön inte är den lättaste att undervisa i.

  • 28.
    John Mwakisisile, Andongwisye
    et al.
    Department of Mathematics, University of Dar es Salaam, Dar es Salaam, Tanzania.
    Larsson, Torbjörn
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Ohlson, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, Faculty of Science & Engineering.
    Mushi, Allen
    Department of Mathematics, University of Dar es Salaam, Dar es Salaam, Tanzania.
    Asset liability management for Tanzania pension funds by stochastic programming2018In: Afrika Statistika, ISSN 2316-090XArticle in journal (Refereed)
  • 29.
    Johnsson, Emma
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Bedömning av problemlösning i skolmatematik.: En litteraturstudie om centrala faktorer vid bedömning av problemlösningsförmåga i årskurs 9.2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna litteraturstudie är att utifrån forskning undersöka vilka faktorer som är centrala vid bedömning av problemlösning i matematiken och koppla detta till kursplaner och betygskriterier.Utifrån tidigare forskning, rapporter och utvärderingar, kursplaner och betygskriterier från Skolverket beskrivs problemlösning, bedömning, kunskap och lärteorier med huvudfokus på bedömning av elevers problemlösningsförmåga.Analysen har visat att det finns vissa frågor som läraren bör tänka på vid bedömning av elevens problemlösningsförmåga; vilka förmågor som ska testas och hur detta ska göras, elevens medvetenhet om vad som ska bedömas, på vilket sätt eleven har förstått uppgiften, elevens möjlighet att lösa problemet, hur eleven har försökt lösa problemet, vilka kunskaper eleven har använt sig av, vilka slutsatser eleven kommit fram till, vilken tillförlitlighet bedömningen har samt vilka kriterier eleven har uppfyllt.

  • 30.
    Kalish, Michael L.
    et al.
    Syracuse University, USA.
    Dunn, John C.
    University of Adelaide, Australia.
    Burdakov, Oleg P.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Sysoev, Oleg
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, Faculty of Arts and Sciences.
    A statistical test of the equality of latent orders2016In: Journal of mathematical psychology (Print), ISSN 0022-2496, E-ISSN 1096-0880, Vol. 70, p. 1-11, article id YJMPS2051Article in journal (Refereed)
    Abstract [en]

    It is sometimes the case that a theory proposes that the population means on two variables should have the same rank order across a set of experimental conditions. This paper presents a test of this hypothesis. The test statistic is based on the coupled monotonic regression algorithm developed by the authors. The significance of the test statistic is determined by comparison to an empirical distribution specific to each case, obtained via non-parametric or semi-parametric bootstrap. We present an analysis of the power and Type I error control of the test based on numerical simulation. Partial order constraints placed on the variables may sometimes be theoretically justified. These constraints are easily incorporated into the computation of the test statistic and are shown to have substantial effects on power. The test can be applied to any form of data, as long as an appropriate statistical model can be specified.

  • 31.
    Karlsson, Anton
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Population Models with Age and Space Structure2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In this thesis, basic concepts of populational models are studied from a theoretical point of view, especially the long term behaviours. All models are at least time dependent with additional age structure, spatial structure. The last model which is an extension of the von Foerster equation, is dependent on all o f these structures and have a long-term solution for large values of time. Modeling population is a frequent subject in modern biology. It is hard to create a model that appears as realistic as possible. First one might consider that a population size is governed by the current size of the population, along with rates of how each individual contributes (give birth), so that the population increases. and how frequent an individual dies, causing the population to decrease in size. However these sort of models can only describe the size of population in a shorter span of time.

  • 32.
    Karlsson, Emelie
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Arvidson, Claes
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Work Distribution for a Heterogeneous Library Staff: A Personnel Task Scheduling Problem2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The distribution of tasks to a heterogeneous work force at libraries and other service institutions is a time consuming task for manual schedulers. In this thesis, we study the possibility of making the assignment using operations research techniques. The problem studied concerns seven days per week, five types of tasks, two types of staff qualifications and around 100 tasks per week to be assigned to the staff. Staff member satisfaction is also taken into account in the scheduling process.

    The main objective is to create an optimal ten week rotating schedule, in which the stand-in staff members are evenly distributed. Such a schedule is considered to be robust, since stand-in staff can replace the regular staff when there is unforseen absence.

    A mathematical model is formulated for the problem and is solved using the commercial solver CPLEX. We also present two different large neighbourhood search heuristic implementations for this problem. The first heuristic assigns complete week blocks to the staff members, while the second one distributes one task at a time. The latter heuristic works better than the former and achieves results comparable to those of the commercial solver. Our conclusion is that the second heuristic works better because it focuses on finding a good weekend distribution before creating the rest of the schedule. A conclusion from our work is that the weekend-worker constellation is the most significant degree of freedom in the problem.

  • 33.
    Kozlov, Vladimir
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Nazarov, Sergei Aleksandrovich
    St. Petersburg State University, St. Petersburg State Polytechnical University, Russian Academy of Sciences, Russia.
    Transmission conditions in a one-dimensional model of bifurcating blood vessel with an elastic wall2015In: Zapiski Nauchnykh Seminarov POMI, ISSN 0132-6678, Vol. 438, p. 138-177Article in journal (Other academic)
    Abstract [en]

    We derive transmission conditions at a bifurcation point in a one-dimensional model of blood vessels by using a three-dimensional model. Both classical Kirchhoff conditions ensuring the continuity of pressure and zero flux flow in the node has to be modified in order to reflect properly the elastic properties of blood vessels and the nodes themselves. A simple approximate calculation scheme for the new physical parameters in the transmission conditions is proposed. We develop a simplified model of straight fragments of arteries with localized defects such as lateral micro-aneurysms and cholesterol plaques – these models also require setting transmission conditions.

  • 34.
    Kozlov, Vladimir
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Vakulenko, Sergey
    Inst. for Mech. Eng. Problems, Russian Acad. Sci., St. Petersburg, ITMO University, St. Petersburg, Russia; Saint Petersburg State University of Industrial Technology and Design, St. Petersburg, Russia.
    Wennergren, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Tkachev, Vladimir
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Biodiversity and robustness of large ecosystems2018In: Ecological Complexity: An International Journal on Biocomplexity in the Environment and Theoretical Ecology, ISSN 1476-945X, E-ISSN 1476-9840, Vol. 36, p. 101-109Article in journal (Refereed)
    Abstract [en]

    We study the biodiversity problem for resource competition systems with extinctions and self-limitationeffects. Our main result establishes estimates of biodiversity in terms of the fundamental parameters ofthe model. We also prove the global stability of solutions for systems with extinctions and large turnoverrate. We show that when the extinction threshold is distinct from zero, the large time dynamics of systemis fundamentally non-predictable. In the last part of the paper we obtain explicit analytical estimates ofecosystem robustness with respect to variations of resource supply which support the R* rule for a systemwith random parameters.

    The full text will be freely available from 2020-08-24 14:03
  • 35.
    Landers, Lena
    Linköping University, Department of Behavioural Sciences and Learning.
    Framgångsfaktorer för elevers lärande i matematik: En kvalitativ studie om speciallärares uppfattningar om matematiksvårigheter och elevers lärande i matematik2015Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En av skolans viktigaste uppgifter är att se till att alla elever utvecklar god taluppfattning, god problemlösningsförmåga samt kommunikativa förmågor och färdigheter i matematik. Tidigare studier visar att det finns många orsaker till att elever hamnar i matematiksvårigheter. I den här studien som har en kvalitativ metodansats undersöker jag speciallärarnas uppfattningar om framgångsfaktorer för elevers lärande i matematik. Utifrån deras erfarenheter kring matematiksvårigheter och deras kunskap om preventioner och interventioner i matematik görs en jämförelse med forskningen i det aktuella området.

    I studien kartläggs vilka faktorer som kan underlätta alla elevers lärande i matematik utifrån ett relationellt-och sociokulturellt perspektiv på lärande eftersom det är väsentligt att undervisningen organiseras och utgår från elevers lärande och behov.

    Utifrån det empiriska materialet har jag gjort en tematisk analys där jag har funnit följande underrubriker: Undervisning, Arbetsminne, Självkänsla, Engagerande undervisning, Artefakt, Synliggöra elevers lärande, Anpassningar för lärande, Intensivundervisning, Alternativa hjälpmedel, Elevaktiv undervisning, Kollegialt lärande samt Engagerade lärare.

    Matematikundervisningens betydelse kommer fram som ett genomgående tema i alla delar. Det är i undervisningen svårigheterna uppstår i matematik men det är även där det finns möjligheter för eleverna att lyckas med sitt lärande i matematik. Det är centralt att det finns arbetssätt som underlättar lärande men framför allt visar studien att den enskilda framgångsfaktorn för elevers lärande i matematik är en skicklig matematiklärare.

  • 36.
    Lindblad, Andreas
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Routing of traffic in an IP-network using combined routing patterns2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In IP networks using the OPSF-principle together with the ECMP-principle, thetraffic is routed in all shortest paths. Weights on links are set by an administrator,not knowing how the resulting routing pattern will become. In this final thesis, I givea heuristic solution to the problem of changing a set of desired routing patterns inan ordered way to make them compatible with each other. An implementation of thealgorithm has been made and some testing with provided data for performance is alsopresented.

  • 37.
    Lindqvist, Jessica
    et al.
    Linköping University, Department of Behavioural Sciences and Learning.
    Lundell, Magdalena
    Linköping University, Department of Behavioural Sciences and Learning.
    Att bemästra talkombinationer i matematik: En experimentell studie i årskurs 52018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 38.
    Lundberg, Anna, L., V.
    et al.
    Department of Pedagogical, Curricular and Professional Studies, University of Gothenburg,Gothenburg,Sweden.
    Kilhamn, Cecilia
    Department of Pedagogical, Curricular and Professional Studies, University of Gothenburg, Gothenburg, Sweden.
    Transposition of Knowledge: Encountering Proportionality in an Algebra Task2018In: International Journal of Science and Mathematics Education, ISSN 1571-0068, E-ISSN 1573-1774, Vol. 16, no 3, p. 559-579, article id 1571-0068Article in journal (Refereed)
    Abstract [en]

    This article reports on an analysis of the process in which knowledge to be taught was transposed into knowledge actually taught, concerning a task including proportional relationships in an algebra setting in a grade 6 classroom. We identified affordances and constraints of the task by describing the mathematical praxeology of the two different types of knowledge exposed, in the task as such and in the activity of the classroom. Through the teacher’s explicit process of reasoning, modeling, revising, solving, and repeatedly explaining the task, we found that the transposition of knowl- edge was seriously affected by the contextualization of the task. Modeling word problems about everyday situations has its limitations and can, as in this case, make the problem unsolvable unless it is accepted as a Btextbook task^ disguised as real but adjusted to the norms of school mathematics. Such constraints may obscure mathe- matical ideas afforded by the task. We conclude that learning opportunities embedded in a task do not necessarily surface when a task is treated in a classroom setting

  • 39.
    Lundberg, Anna, L. V.
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Muhrman, Karolina
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Att konstruera matematikuppgifter på yrkesprogram2015Other (Other academic)
    Abstract [sv]

    Uppgifter har en central roll inom matematikundervisning, och eftersom utbudet av yrkesrelaterade uppgifter är begränsat är det viktigt förmatematiklärarepå yrkesprogram att kunna skapa nya sådana uppgifter.

  • 40.
    Lundberg, Anna, L., V.
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Ödmark, Krister
    Umeå Universitet, Umeå Sverige.
    Digital teknik, digitala medier och andra verktyg2015Other (Other academic)
    Abstract [sv]

    I den svenska matematikundervisningen har ett trendbrott inträffat i och med att billiga bärbara datorer, interaktiva skrivtavlor, sofistikerade mobiltelefoner och en i högre grad problembaserad undervisning blivit allt vanligare. I det övergripande syftet i ämnesplanen för matematik betonas att eleverna ska ”ges möjlighet att utveckla sin förmåga att använda digital teknik, digitala medier och även andra verktyg som kan förekomma inom karaktärsämnena” (Skolverket, 2011). Digitalaverktygfinns även med i kunskapskraven för alla betygsstegi kursen Matematik 1. Där ingår att eleven ”löser uppgifter av standardkaraktär med viss säkerhet, både utan och med digitala och andra praxisnära verktyg” (Skolverket, 2011).

    • Digital teknik (t.ex.responsprogram, utbildningsplattformar, interaktiva tavlor, applikationer, bokföringsprogram, bokningsprogram, schema, kalkylprogram)
    • Digitala medier (internet, mobiltelefoner, surfplattoroch dator)
    • Verktyg inom karaktärsämnen(sinushylla, linjaler med skala, mätverktyg, termometer, våg mm.)
  • 41.
    Lundberg, Anna
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Muhrman, Karolina
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Matematik i Yrkesutbildningen - en historisk överblick2015Other (Other academic)
    Abstract [sv]

    Texten inleds med några nedslag i yrkesutbildningens historia med relation till vilken matematik som krävdes i läroplanerna. Därefterges en beskrivning av hur yrkesutbildningen ser ut i Tyskland och Australien för att visa hur Sverige står sig i jämförelse med andra länder.

  • 42.
    Marciniak, Krzysztof
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Blaszak, Maciej
    Department of Physics, Adam Mickiewicz University, Poznan, Poland.
    On Reciprocal Equivalence of Stäckel Systems2012In: Studies in applied mathematics (Cambridge), ISSN 0022-2526, E-ISSN 1467-9590, Vol. 129, no 1, p. 26-50Article in journal (Refereed)
    Abstract [en]

    In this paper we ivestigate Stäckel transforms between different classes of parameter-dependent Stäckel separable systems of the same dimension. We show that the set of all Stäckel systems of the same dimension splits to equivalence classes so that all members within the same class can be connected by a single Stäckel transform. We also give an explicit formula relating solutions of two Stäckel-related systems. These results show in particular that any two geodesic Stäckel systems are Stäckel equivalent in the sense that it is possible to transform one into another by a single Stäckel transform. We also simplify proofs of some known statements about multiparameter Stäckel transform.

  • 43.
    Morén, Björn
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Utilizing problem specic structures in branch and bound methods for manpower planning2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is about solving the manpower planning problem concerning stangand transitioning of pilots. The objective of the planning is to have enoughpilots to satisfy the demand while minimizing the cost. The main decisions totake are how many pilots to hire, which pilots to train and which courses toschedule. The planning problems that arise are both large and dicult whichmakes it important to use ecient solution methods. Seniority rules betweenpairs of pilots are the most complicating factor.A major part in the solution process is the solving of mixed integer programs.The emphasis in the thesis is to develop and test adaptations of the branch andbound algorithm to solve mixed integer programs faster. One of these is abranching principle that takes a problem specic structure into account. Agraph of implications is constructed from the seniority rules and this graph isthen used to estimate the impact of each branching candidate. The implementedmethods outperform the software XPRESS on some instances, while for mostinstances the performance is comparable.

  • 44.
    Muhrman, Karolina
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Lundberg, Anna
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Matematik på yrkesprogram - ur ett didaktiskt perspektiv2015Other (Other academic)
    Abstract [sv]

    Sedan 1990-talet läser alla elever som går i den svenska gymnasieskolan minst 100 poäng matematik under sin gymnasieutbildning oavsett om det handlar om en yrkesutbildning eller e n studieförberedande utbildning. Att det sedan 1990-talet är obligatoriskt för yrkeselever att läsa matematik, tyder på att det anses viktigt med matematikkunskaper. För fördjupning om utvecklingen av matematik på yrkesprogram se fördjupningsmaterial: Matematik i yrkesutbildning – en historisk överblick. Varför är det då viktigt med goda matematikkunskaper för yrkeselever och hur kan matematikundervisningen på yrkesprogram organiseras så att eleverna får goda matematikkunskaper? Vad behöver eleverna lära sig och vilket syfte har matematikundervisningen? Dessa frågor är centrala för matematikundervisningen på yrkesprogram och är något som kan behöva diskuteras, delvis på grund av ämnesplanernas utformning för matematikämnet, men främst för att många branscher idag kräver goda matematikkunskaper. Frågorna o van benämns ibland som didaktiska frågor. I denna text diskuteras matematikundervisning på yrkesprogram med utgångspunkt i didaktiska frågor som rör matematikundervisningens syfte, innehåll och organisering. Innehållet i texten är delvis hämtat från Muhrman ( 2016 ) doktors avhandling.  

  • 45.
    Muhrman, Karolina
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Lundberg, Anna, L., V.
    Linköping University, Department of Behavioural Sciences and Learning, Education and Adult Learning. Linköping University, Faculty of Educational Sciences.
    Dypbukt, Wenche
    Matematikksenteret, Trondheim, Norge.
    Jens Arne, Meistad
    Matematikksenteret, Trondheim, Norge.
    Aina, Fardal
    Horten vgs skole Norge, Horten, Norge.
    Liebich, Rolf
    Dag Vassbotn.
    Ödmark, Krister
    Umeå universitet, Umeå, Sverige.
    Popov, Oleg
    Umeå universitet, Umeå, Sverige.
    Dahlberg, Johan
    Erik Dahlbergsgymnasiet, Jönköping, Sverige.
    Uppgiftsbanken: Gymnasieskola, modul: Undervisa matematik på yrkesprogram2015Other (Other academic)
    Abstract [sv]

    Denna uppgiftsbank innehåller uppgifter med varierat innehåll och svårighetsgrad. Uppgifterna är av varierande karaktär och uppfyller i olika grad kriterierna från checklistan i texten ”Att konstruera matematikuppgifter på yrkesprogram”. Uppgifterna kan användas i undervisningen eller fungera som ett diskussionsunderlag vid utveckling av infärgade uppgifter. Studera gärna uppgifterna tillsammans med yrkeslärare.

    Till uppgifterna finns stöd för hur man kan planera och arbeta med uppgifterna i klassrummet. Det finns kopplingar till centralt innehåll i Matematik 1a, yrkesämnenas centrala innehåll och examensmålen för yrkesprogrammen. Eftersom kurserna i yrkesämnena läggs ut lokalt finns det ingen samstämmighet i vilken ordning och under vilken termin de läses på olika skolor. Det kan därför vara så att det centrala innehåll i yrkesämnena inte är aktuellt just då men det kan ändå vara bra för eleverna att känna till det. Till några av uppgifterna ges för slag på hur man kan variera eller utveckla dem. I modulen Undervisa matematik på yrkesprogram del 5: Modellering och problemlösning finns några förslag på hur uppgifterna kan göras till Fermiproblem.

    I Skolverkets bedömningsportal finns uppgifter för yrkesprogram. En del av uppgifterna är lösenordsskyddade. För att komma åt det skyddade materialet behövs inloggningsuppgifter och behörighet till ämnet eller kursen. Information om hur du som lärare får inloggningsuppgifter har skickats till rektorn på din skola. Du hittar bedömningsportalen här: https://bp.skolverket.se/.

  • 46. Narukawa, Yasuo
    et al.
    Stokes, Klara
    Torra, Vicenç
    Fuzzy measures and comonotonicity on multisets2011In: Modeling Decisions for Artificial Intelligence - 9th International Conference, MDAI 2012 / [ed] Vicenç Torra, Yasuo Narukawa, Jianping Yin, Jun Long, Springer, 2011Chapter in book (Refereed)
  • 47.
    Olsson, Per-Magnus
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Methods for Network Optimization and Parallel Derivative-free Optimization2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis is divided into two parts that each is concerned with a specific problem.

    The problem under consideration in the first part is to find suitable graph representations, abstractions, cost measures and algorithms for calculating placements of unmanned aerial vehicles (UAVs) such that they can keep one or several static targets under constant surveillance. Each target is kept under surveillance by a surveillance UAV, which transmits information, typically real time video, to a relay UAV. The role of the relay UAV is to retransmit the information to another relay UAV, which retransmits it again to yet another UAV. This chain of retransmission continues until the information eventually reaches an operator at a base station.

    When there is a single target, then all Pareto-optimal solutions, i.e. all relevant compromises between quality and the number of UAVs required, can be found using an efficient new algorithm. If there are several targets, the problem becomes a variant of the Steiner tree problem and to solve this problem we adapt an existing algorithm to find an initial tree. Once it is found, we can further improve it using a new algorithm presentedin this thesis.

    The second problem is optimization of time-consuming problems where the objective function is seen as a black box, where the input parameters are sent and a function valueis returned. This has the important implication that no gradient or Hessian information is available. Such problems are common when simulators are used to perform advanced calculations such as crash test simulations of cars, dynamic multibody simulations etc. It is common that a single function evaluation takes several hours.

    Algorithms for solving such problems can be broadly divided into direct search algorithms and model building algorithms. The first kind evaluates the objective function directly, whereas the second kind builds a model of the objective function, which is then optimized in order to find a new point where it is believed that objective function has agood value. Then the objective function is evaluated in that point.

    Since the objective function is very time-consuming, it is common to focus on minimizing the number of function evaluations. However, this completely disregards the possibility to perform calculations in parallel and to exploit this we investigate different ways parallelization can be used in model-building algorithms. Some of the ways to do this is to use several starting points, generate several new points in each iteration, new ways of predicting a point’s value and more.

    We have implemented the parallel extensions in one of the state of the art algorithms for derivative-free optimization and report results from testing on synthetic benchmarksas well as from solving real industrial problems.

  • 48.
    Olteanu, Constanta
    et al.
    Linnéuniversitetet, Växjö, Sverige.
    Lundberg, Anna, L., V.
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Ödmark, Krister
    Umeå universitet, Umeå, Sverige.
    Interaktion i klassrum2015Other (Other academic)
    Abstract [sv]

    Vi fokuserar i denna text på hur digitala hjälpmedel och verktyg påverkar möjligheter till interaktion i klassrummet.

  • 49.
    Pettersson, Simon
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Elevers begreppsbilder av komplexa tal: En litteraturstudie av matematikdidaktisk forskning2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie är en kartläggning av empiriskt visade begreppsbilder av komplexa tal, genom en systematisk litteraturstudie av matematikdidaktisk forskningslitteratur. Litteraturen togs fram genom både ett strategiskt urval och ett snöbollsurval. Det konstaterades tidigt att det förekom en stor brist av matematikdidaktisk forskning inom området komplexa tal. Totalt hittades fyra texter: två forskningsartiklar, en doktorsuppsats och ett konferensbidrag. Texterna baserades på bland annat intervjuer, observationer och enkätundersökningar. Åtta begreppsbilder hittades i kartläggningen: komplexa tal är ett matematiskt trick, ett tvådimensionellt tal, ett symboliskt uttryck, ett obegripligt mysterium, egentligen inget tal, har en storleksordning, komplexa rötters natur ifrågasätts och imaginära enheten uppfattas som en enhetsvektor. Det diskuteras i arbetet huruvida det går att avgöra om en begreppsbild är "nära" en formell begreppsdefinition, och det söks eventuella förklaringar och lösningar till vissa missförstånd kring komplexa tal. Bland annat bör lärare eventuellt utveckla elevers talförståelse, förmåga att visualisera komplexa tal, samt erbjuda tydligare användningsområden för komplexa tal. Lärare kan med detta arbete identifiera elevers eventuella begreppsbilder och missuppfattningar som stöd för bedömning av elevers begreppsförmåga. Kartläggningen gör inget anspråk på att vara heltäckande, och vidare studier kring begreppsbilder av komplexa tal efterfrågas. Även fler studier om komplexa tal i allmänhet behövs.

  • 50.
    Pielaszkiewicz, Jolanta
    et al.
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    von Rosen, Dietrich
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Singull, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    Cumulant-moment relation in free probability theory2014In: Acta et Commentationes Universitatis Tartuensis de Mathematica, ISSN 1406-2283, E-ISSN 2228-4699, Vol. 18, no 2, p. 265-278Article in journal (Refereed)
    Abstract [en]

    The goal of this paper is to present and prove a cumulant-moment recurrent relation formula in free probability theory. It is convenient tool to determine underlying compactly supported distribution function. The existing recurrent relations between these objects require the combinatorial understanding of the idea of non-crossing partitions, which has been considered by Speicher and Nica. Furthermore, some formulations are given with additional use of the Möbius function. The recursive result derived in this paper does not require introducing any of those concepts. Similarly like the non-recursive formulation of Mottelson our formula demands only summing over partitions of the set. The proof of non-recurrent result is given with use of Lagrange inversion formula, while in our proof the calculations of the Stieltjes transform of the underlying measure are essential.

12 1 - 50 of 68
CiteExportLink 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